Prof. Clifford L. Henderson Profile

Prof. Clifford L. Henderson

Dean, College of Engineering

SPIE Involvement:

Conference Program Committee | Author

Area of Expertise:

lithography , photoresists , functional materials , polymers , nanofabrication , semiconductor processing

Websites:

Company Website

Profile Summary

Dr. Clifford L. Henderson is the Dean of the College of Engineering at the University of Alabama and a Professor in the Department of Chemical and Biological Engineering. Prior to joining the University of Alabama in 2022, he previously served as Department Chair for the Department of Chemical, Biological, and Materials Engineering at the University of South Florida from 2016 through 2022, and prior to that spent the first 18 years of his academic career at the Georgia Institute of Technology. Dean Henderson received his Bachelor of Science in Chemical Engineering with Highest Honors from the Georgia Institute of Technology and his Master of Science and Doctor of Philosophy in Chemical Engineering from The University of Texas at Austin.

Dean Henderson’s research focuses on problems at the intersection of chemical engineering, organic and polymeric materials science, and micro- and nanotechnology in a variety of application areas including electronics, energy, and biotechnology. Dean Henderson has served in a variety of national leadership roles related to his academic engineering career and his research interests, including prior service as the Functional Materials Program Director within the Civil, Mechanical, and Manufacturing Innovation (CMMI) Division at the National Science Foundation.

Dean Henderson has received numerous awards and recognition for his research and service work including an NSF CAREER Award, the inaugural Intel/STC Outstanding Lithography Researcher Award, the AIChE Herb Epstein Award, and the AIChE Gary Leach Award. Dr. Henderson has been elected as a Fellow of the International Society for Optics and Photonics (SPIE) in 2010, a Fellow of the American Association for the Advancement of Science (AAAS) in 2017, and a Fellow of the American Institute of Chemical Engineers (AIChE) in 2018.

Publications (119)

Proceedings Article | 23 March 2020 Paper

Paper

Understanding and mitigating bridge defects in block copolymer directed self-assembly through computational materials design and optimization

Jakin Delony, Peter Ludovice, Clifford Henderson

Proceedings Volume 11326, 113261K (2020) https://doi.org/10.1117/12.2563896

KEYWORDS: Bridges, Directed self assembly, Thin films, Annealing, Computer simulations, Polymers, Molecular bridges

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Proceedings Article | 25 March 2019 Paper

Paper

Block copolymer line roughness and annealing kinetics as a function of chain stiﬀness

Caleb Breaux, Peter Ludovice, Clifford Henderson

Proceedings Volume 10960, 109601L (2019) https://doi.org/10.1117/12.2526417

KEYWORDS: Polymers, Line edge roughness, Line width roughness, Interfaces, Annealing, Thin films, Diffusion, Optical lithography, Resistance, Directed self assembly

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Proceedings Article | 25 March 2019 Paper

Paper

Mitigation of line edge roughness and line width roughness in block copolymer directed self-assembly through polymer composition molecular weight manipulation

Jakin Delony, Peter Ludovice, Clifford Henderson

Proceedings Volume 10960, 109601M (2019) https://doi.org/10.1117/12.2526418

KEYWORDS: Line edge roughness, Line width roughness, Thin films, Directed self assembly, Polymers, Computer simulations, Optical lithography, Molecular self-assembly, Modulation, Etching

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The semiconductor community is well aware of the challenges that exist in developing lithographic methods that can pattern features at sub-20 nm periodic feature spacing (pitch, L₀). Optical lithography already utilizes complex multiple patterning schemes to overcome diffraction limitations at 193-nm exposure wavelengths, and the delayed insertion of EUV lithography will likely require the use of multiple patterning or other assistive processes to further reduce the achievable feature sizes. An alternative to these techniques employs the directed self-assembly (DSA) of block copolymers. Block copolymers (BCPs) can naturally micro-phase separate into morphologies such as lamellae, cylinders, spheres, and gyroids at length scales down to sub-10 nm dimensions. Using the ability of BCPs to micro-phase separate in conjunction with alignment methods such as graphoepitaxy and chemoepitaxy to produce well-ordered structures, a process referred to as DSA, offers a possible method for producing sub-20 nm features in conjunction with optical patterning processes at greatly reduced cost and complexity. One of the many challenges in implementing line-space type DSA processes is the lack of methods for effective modulation and tuning of the pattern pitch (L₀) produced by a given BCP. Previous studies have shown that blending homopolymer into the BCP thin films can allow for tuning of both: (1) L₀to be larger than that provided naturally by the BCP's molecular weight (MW) and (2) the relative size line-space size ratio. However, this tuning ability comes at the expense of increased line edge roughness (LER) and line width roughness (LWR). It has also been shown that either higher or lower MW BCP can be blended into a primary BCP in order to modulate and tune the pattern pitch produced from the BCP mixture, but the effects of this BCP blending on pattern LER and LWR have not been explored or reported in detail. In this study, coarse-grained molecular dynamics simulations of BCP DSA on a chemoepitaxial underlayer were implemented to characterize the impacts that blending controlled amounts of two different MW BCPs together have on DSA pattern LER and LWR. The blends shown here had LER and LWR values as much as 20% higher than those of pure, monodisperse BCPs; however, reducing the MW difference between the 2 BCPs could reduce this effect.

Proceedings Article | 4 April 2018 Paper

Paper

Effect of homopolymer concentration on LER and LWR in block copolymer/homopolymer blends

Caleb Breaux, Jakin Delony, Peter Ludovice, Clifford Henderson

Proceedings Volume 10584, 105841H (2018) https://doi.org/10.1117/12.2318642

KEYWORDS: Line edge roughness, Line width roughness, Interfaces, Polymers, Thin films, Directed self assembly, Computer simulations, Device simulation, Solids, Molecular self-assembly

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SPIE Journal Paper | 22 November 2017 Open Access

Open Access

Chemoepitaxial guiding underlayers for density asymmetric and energetically asymmetric diblock copolymers

Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 16, Issue 04, 043505, (November 2017) https://doi.org/10.1117/12.10.1117/1.JMM.16.4.043505

KEYWORDS: Interfaces, Thin films, Polymers, Bridges, Optical lithography, Polymerization, Device simulation, Skin, Algorithms, Directed self assembly

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SPIE Journal Paper | 27 October 2017

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

Benjamin D. Nation, Andrew J. Peters, Richard A. Lawson, Peter J. Ludovice, Clifford L. Henderson

JM3, Vol. 16, Issue 04, 043502, (October 2017) https://doi.org/10.1117/12.10.1117/1.JMM.16.4.043502

KEYWORDS: Line edge roughness, Line width roughness, Optical lithography, Double patterning technology, Interfaces, Directed self assembly, Polymers, Polymerization, Etching, Chemical species

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SPIE Journal Paper | 20 October 2017 Open Access

Open Access

Free energy of defects in chemoepitaxial block copolymer directed self-assembly: effect of pattern density and defect position

Benjamin Nation, Caleb Breaux, Peter Ludovice, Clifford Henderson

JM3, Vol. 16, Issue 04, 043501, (October 2017) https://doi.org/10.1117/12.10.1117/1.JMM.16.4.043501

KEYWORDS: Directed self assembly, Thermodynamics, Polymers, Annealing, Nanoimprint lithography, Extreme ultraviolet lithography, Device simulation, Optical lithography, Semiconductors, Lithography

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Proceedings Article | 19 April 2017 Paper

Paper

Free energy of defects in chemoepitaxial block copolymer directed self-assembly: effect of pattern density and defect position

Benjamin Nation, Caleb Breaux, Peter Ludovice, Clifford Henderson

Proceedings Volume 10146, 101461T (2017) https://doi.org/10.1117/12.2276197

KEYWORDS: Thermodynamics, Directed self assembly, Polymers, Device simulation, Annealing, Optical lithography, Thin films, Feature extraction, Computer simulations, Molecular self-assembly

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SPIE Journal Paper | 10 May 2016 Open Access

Open Access

Calculations of the free energy of dislocation defects in lamellae forming diblock copolymers using thermodynamic integration

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 15, Issue 02, 023505, (May 2016) https://doi.org/10.1117/12.10.1117/1.JMM.15.2.023505

KEYWORDS: Directed self assembly, Thermodynamics, Polymers, Interfaces, Computer simulations, Polymerization, Systems modeling, Binary data, Thin films, Semiconductors

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Proceedings Article | 1 April 2016 Paper

Paper

Chemoepitaxial guiding underlayers for density asymmetric and energetically asymmetric diblock copolymers

Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9777, 97771V (2016) https://doi.org/10.1117/12.2219255

KEYWORDS: Directed self assembly, Molecular self-assembly, Lithography, Optical lithography, Industrial chemicals, Bridges, Polymers, Skin, Polymerization, Algorithms, Microelectronics, Process modeling, Device simulation

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SPIE Journal Paper | 8 March 2016

Coarse-grained molecular dynamics modeling of the kinetics of lamellar block copolymer defect annealing

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 15, Issue 01, 013508, (March 2016) https://doi.org/10.1117/12.10.1117/1.JMM.15.1.013508

KEYWORDS: Directed self assembly, Thin films, Interfaces, Polymers, Annealing, Diffusion, Scattering, Computer simulations, Process control

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Proceedings Article | 20 March 2015 Paper

Paper

Optimizing performance in cross-linking negative-tone molecular resists

Richard Lawson, Hannah Narcross, Brandon Sharp, Jun Sung Chun, Mark Neisser, Laren Tolbert, Clifford Henderson

Proceedings Volume 9425, 94250A (2015) https://doi.org/10.1117/12.2086007

KEYWORDS: Silicon, Molecules, Optical lithography, Extreme ultraviolet, Standards development, Oxides, Glasses, Polymerization, Switches, Polymers

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Proceedings Article | 20 March 2015 Paper

Paper

Effect of molecular resist structure on glass transition temperature and lithographic performance in epoxide functionalized negative tone resists

Hannah Narcross, Richard Lawson, Brandon Sharp, Jun Sung Chun, Mark Neisser, Laren Tolbert, Clifford Henderson

Proceedings Volume 9425, 94250C (2015) https://doi.org/10.1117/12.2086027

KEYWORDS: Glasses, Lithography, Polymerization, Polymers, Extreme ultraviolet lithography, Diffusion, Scanning electron microscopy, Extreme ultraviolet, Optical lithography, Light sources

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Proceedings Article | 20 March 2015 Paper

Paper

Base developable negative tone molecular resist based on epoxide cross-linking

Brandon Sharp, Richard Lawson, Ashten Fralick, Hannah Narcross, Jun Sung Chun, Mark Neisser, Laren Tolbert, Clifford Henderson

Proceedings Volume 9425, 94251S (2015) https://doi.org/10.1117/12.2086039

KEYWORDS: Glasses, Standards development, Polymers, Polymerization, Molecules, Scanning electron microscopy, Photoresist developing, Semiconducting wafers, Silicon, Line edge roughness

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Proceedings Article | 19 March 2015 Paper

Paper

Effect of chemoepitaxial guiding underlayer design on the pattern quality and shape of aligned lamellae for fabrication of line-space patterns

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231J (2015) https://doi.org/10.1117/12.2085526

KEYWORDS: Line edge roughness, Chemical analysis, Optical lithography, Polymers, Double patterning technology, Data modeling, Molecular self-assembly, Chemical species, Thin films, Directed self assembly

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Proceedings Article | 19 March 2015 Paper

Paper

Investigating SEM metrology effects using a detailed SEM simulation and stochastic resist model

Richard Lawson, Clifford Henderson

Proceedings Volume 9424, 94240K (2015) https://doi.org/10.1117/12.2086051

KEYWORDS: Scanning electron microscopy, Line edge roughness, Line scan image sensors, 3D modeling, Metrology, Monte Carlo methods, Surface roughness, Scattering, 3D metrology, Stochastic processes

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Proceedings Article | 19 March 2015 Paper

Paper

Effect of χN and underlayer composition on self-assembly of thins films of block copolymers with energy asymmetric blocks

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231L (2015) https://doi.org/10.1117/12.2086047

KEYWORDS: Interfaces, Polymers, Thin films, Systems modeling, Molecular self-assembly, Computer simulations, Lithography, Physics, Visualization, Directed self assembly

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Proceedings Article | 19 March 2015 Paper

Paper

Coarse-grained molecular dynamics modeling of the kinetics of lamellar BCP defect annealing

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9423, 94231Y (2015) https://doi.org/10.1117/12.2085518

KEYWORDS: Thin films, Polymers, Interfaces, Diffusion, Neodymium, Bridges, Annealing, Computer simulations, Process control, Directed self assembly

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SPIE Journal Paper | 20 August 2014

Simulation study of the effect of differences in block energy and density on the self-assembly of block copolymers

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

JM3, Vol. 13, Issue 03, 031308, (August 2014) https://doi.org/10.1117/12.10.1117/1.JMM.13.3.031308

KEYWORDS: Interfaces, Polymers, Thin films, Computer simulations, Molecular self-assembly, Lithography, Physics, Picosecond phenomena, Manufacturing, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Paper

Understanding defects in DSA: calculation of free energies of block copolymer DSA systems via thermodynamic integration of a mesoscale block-copolymer model

Andrew Peters, Richard Lawson, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90492E (2014) https://doi.org/10.1117/12.2046664

KEYWORDS: Polymers, Thermodynamics, Systems modeling, Monte Carlo methods, System integration, Molecular interactions, Semiconductors, Motion models, Polymerization, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Paper

Effect of guiding layer topography on chemoepitaxially directed self-assembly of block copolymers for pattern density multiplication

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90492K (2014) https://doi.org/10.1117/12.2046629

KEYWORDS: Polymers, Computer simulations, Chemical species, Process modeling, Molecular self-assembly, Chemical engineering, Optical alignment, Semiconductor manufacturing, Feature extraction, Directed self assembly

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Proceedings Article | 28 March 2014 Paper

Paper

Simulation study of the effect of differences in block energy and density on the self-assembly of block copolymers

Richard Lawson, Andrew Peters, Benjamin Nation, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90490S (2014) https://doi.org/10.1117/12.2046603

KEYWORDS: Interfaces, Polymers, Thin films, Computer simulations, Lithography, Physics, Chemistry, Manufacturing, Photoresist materials, Directed self assembly

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Implementation of directed self-assembly (DSA) of block copolymers (BCPs) introduces a series of engineering challenges that have not been completely addressed in previous block copolymer and lithography studies. One of the required innovations for further DSA development and implementation is the accurate simulation of specific block copolymer chemistries and their interactions with interfaces. Many of the BCP simulation tools developed so far have limitations or difficulty in terms of matching many of the common issues found in experimental BCP systems such as polydispersity and different statistical segment lengths. One of the potentially most important issues is the fact that real BCPs often have block energy and/or density asymmetry, meaning that each block has a different homopolymer density and/or cohesive energy density (CED). A simulation of BCP behavior and DSA processes based on molecular dynamics (MD) of coarse-grained polymer chains has been developed that can independently parameterize and control the density and CED of each block to more accurately match the asymmetry found in experimental BCPs. This model was used to study the effect of block asymmetry on the order-disorder transition (ODT), domain scaling, and self-assembly of thin films of BCPs. BCPs whose blocks each have a different density show deviations from the mean-field ODT coexistence curve, exhibiting an order-disorder transition or co-existence curve that is asymmetric with shifts and tilts in the direction of majority highest density block. This impact of density and cohesive energy differences diblock copolymers on their phase behavior can explain some of the unexpected shapes found experimentally in BCP ODT curves. Asymmetry in the BCP block energy or density does not appear to have a significant effect on domain scaling behavior compared to the mean-field estimates. Self-assembly of thin films of BCPs with mismatches in CED shows significant deviations in the expected morphologies from ones simulated using equivalent densities and cohesive energy densities. The lowest CED block has a strong propensity to segregate to and “wet” the free interface at the top of the film because it has the lowest energy penalty for the loss of interactions with other chains at the free surface relative to the bulk. This gives rise to an effective “skinning” of the film by the lowest CED block for almost the entire potential range of underlayer compositions and film thicknesses. Such materials will be extremely difficult to successfully pattern transfer for a lithographically useful process because they will not form vertically aligned morphologies through the entire film thickness. This CED mismatch also gives rise to a large number of non-bulk morphologies and deviations from bulk behavior including changing vertical-to-horizontal morphologies through film depth, compression and expansion of domain sizes to match film thickness dimensions, and island and hole formation among others. Increasing the χN value can potentially suppress some of these non-idealities due to CED asymmetry, but the required χN to overcome these issues will differ from polymer to polymer depending on the magnitude of the CED asymmetry.

Proceedings Article | 28 March 2014 Paper

Paper

Predicting process windows for pattern density multiplication using block copolymer directed self-assembly in conjunction with chemoepitaxial guiding layers

Benjamin Nation, Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 9049, 90491C (2014) https://doi.org/10.1117/12.2046626

KEYWORDS: Polymers, Chemical species, Molecular self-assembly, Statistical modeling, Lithography, Computer simulations, Chemical analysis, Optical lithography, Physics, Directed self assembly

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Proceedings Article | 27 March 2014 Paper

Paper

Methods of controlling cross-linking in negative-tone resists

Richard Lawson, Jun Sung Chun, Mark Neisser, Laren Tolbert, Clifford Henderson

Proceedings Volume 9051, 90510Q (2014) https://doi.org/10.1117/12.2046616

KEYWORDS: Line edge roughness, Polymerization, Optical lithography, Extreme ultraviolet, Molecules, Deep ultraviolet, Polymers, Diffusion, Glasses, Control systems

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Negative tone resists based on cross-linking via epoxide/cationic polymerization have a variety of potential advantages over more traditional positive tone resists based on photoacid catalyzed deprotection including low outgassing, intrinsic diffusion control, and improved pattern collapse performance through the higher modulus provided by a cross-linked network. Based on the promising baseline performance achieved previously in simple negative tone systems composed only of an epoxide functionalized molecular glass and a photoacid generator, a series of different methods and additives that can be used to control the extent and rate of cross-linking in such systems have been developed and are reported here which allow for even further improvement in resist performance. Simple addition of base quencher, as is used in conventional chemically amplified resists, is ineffective in these systems because the patterning reaction mechanism is different. Any control method must work by modifying the extent and rate of cationic polymerization of epoxides. By adding molecules containing phenolic OH groups to such an epoxide resist, one can slow the extent of cross-linking due to introduction of an additional reaction pathway and often a concomitant increase in the resist resin glass transition temperature. Generalized additives similar to base quencher were also developed based on the addition of strong nucleophiles such as triphenylphosphine which act essentially as chain termination agents. This approach allows for improved resolution and LER in negative tone epoxide resist systems. A more superior additive was developed that can be described as a photodecomposable nucleophile (PDN). The unexposed PDN acts similarly to the strong nucleophile additives in that it terminates chain propagation. Upon exposure, the PDN can act like a chain transfer agent or an additional initiator, but no longer has the effect of completely terminating chain propagation. This approach allows for high levels of control in the nominally unexposed regions of the resist, but maintains high efficiency of cross-linking in the most highly exposed regions. One particular implementation of a PDN used in this study is the blending of a PAG (i.e. triphenylsulfonium triflate, TPS-Tf) with a more nucleophilic anion that plays the role of a PDN, with the common and highly effective, non-nucleophilic PAG that is conventionally used in epoxide photopolymerizations (i.e. triphenylsulfonium hexafluoroantimonate, TPS-SbF₆). Addition of only a few percent of TPS-Tf to a baseline epoxide resist formulation shows a 5-10 nm improvement in ultimate resolution and a reduction in LER to around 65% as compared to the baseline resist without the PDN additive while only incurring a moderate increase in imaging dose. By modulating the amount of the different polymerization control additives, the performance of a particular epoxide resist was improved from a resolution of greater than 30 nm half pitch and an LER of around 9 nm to a resolution of ~20 nm half pitch, with an LER of around 4 nm, and a sensitivity of 18 mJ/cm². By increasing the additive loading even further, the resolution was improved to ~18 nm half pitch, although with an increase in imaging dose to 39 mJ/cm2.

Proceedings Article | 27 March 2014 Paper

Paper

Positive tone cross-linked resists based on photoacid inhibition of cross linking

Richard Lawson, Jun Sung Chun, Mark Neisser, Laren Tolbert, Clifford Henderson

Proceedings Volume 9051, 90510E (2014) https://doi.org/10.1117/12.2046619

KEYWORDS: Molecules, Polymerization, Optical lithography, Polymers, Glasses, Extreme ultraviolet lithography, Extreme ultraviolet, Deep ultraviolet, Switches, Photoresist materials

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Proceedings Article | 10 April 2013 Paper

Paper

Postiive tone resists based on network deploymerization of molecular resists

Richard Lawson, Jing Cheng, Ameneh Cheshmehkani, Laren Tolbert, Clifford Henderson

Proceedings Volume 8682, 868221 (2013) https://doi.org/10.1117/12.2021141

KEYWORDS: Polymers, Deep ultraviolet, Electron beam lithography, Molecules, Line edge roughness, Chemically amplified resists, Capillaries, Lithography, Extreme ultraviolet lithography, Optical lithography

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Conventional chemically amplified resists have several issues that can potentially limit their capability for sub-40 nm imaging. One of the major issues at this size scale is that the mechanical strength of positive tone CARs limits the amount of stress they can withstand during development, rinse, and drying, thus leading to problems with pattern collapse due to the high capillary forces generated during drying. This problem is exasperated by the fact that linear polymers show dramatically reduced modulus at sub-50 nm features sizes. To improve on this problem, we have made a positive tone resist based on network depolymerization of molecular resists. The resist thermally cross-links after being spin cast into thin film form through reactions between vinyl ether groups and carboxylic acid groups. By cross-linking the resist to form a dense three dimensional polymer network, the mechanical strength of the resist is greatly improved compared to linear polymers. The network is depolymerized using an acid catalyzed reaction to create development contrast that allows for patterning of the resist via development in either aqueous base or organic solvent. One drawback of the current resist design is that the free carboxylic acids on the resist molecule appear to react in solution at room temperature with both the vinyl ether groups on adjacent molecules and with any added base quencher. These reactions cause reduced effectiveness of the base quencher and produce a noticeable resist shelf life problem. Despite these limitations, the material was used to compare the effect of development in aqueous base versus organic solvent. The resist formulated in this work showed a DUV sensitivity of 7 mJ/cm² and a contrast of 5.2 for development in either solvent or aqueous base. Under 100 keV e-beam imaging, the material showed 40 nm resolution for both development types. In standard 0.26 N TMAH, the dose-to-size was 84 μC/cm² with 3σ LER of 14.2 nm. Using methyl isobutyl ketone for organic solvent development, the dose-to-size was 104 μC/cm² with 3σ LER of 7.4 nm.

Proceedings Article | 5 April 2013 Paper

Paper

Tuning domain size of block copolymers for directed self assembly using polymer blending: molecular dynamics simulation studies

Richard Lawson, Andrew Peters, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 86801Z (2013) https://doi.org/10.1117/12.2021442

KEYWORDS: Polymers, Critical dimension metrology, Molecular self-assembly, Lithography, Interfaces, Image segmentation, Directed self assembly, Polymerization, Computer simulations, Silver

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A 10% batch-to-batch variation in molecular weight for a low polydispersity block copolymer (BCP) used for DSA lithography could result in more than a 6% change in critical dimension (CD). Therefore, there is a strong motivation and need to develop and understand methods for fine-tuning the domain size of DSA BCPs to meet the CD and pitch specifications that will be required for practical implementation of DSA processes. This study investigates two methods of fine-tuning the domain size of a specific batch of BCP through blending of the BCP with another polymer, either 1. a set of similar homopolymers (HPs) or 2. a similar BCP of different molecular weight. Each method was investigated and compared using a coarse grained molecular dynamics simulation. For BCP-HP blends, the domain size increases as the amount of HP increases because the HPs tend to slightly swell the BCP domains. A design heuristic was developed for guiding the determination of how much HP to add to obtain a desired pitch. For blends of different molecular weight BCPs, two different scaling regimes were identified; one regime is majority large chains and the other regime is majority small chains. Based on the simulation results, the domain scaling can be mapped across the full range of blends by simply measuring three points: the pure small chain domain size, the pure large chain domain size, and a 50/50 blend of the small and large chains. Comparing the two different blending methodologies, BCP blending with other BCPs is a more versatile approach because it can be used to either increase or decrease the domain size of a base BCP while HP blending can only increase the domain size. HP blending is also potentially problematic because the HPs tends to aggregate in the middle of each block’s half domain which can have a significant effect on CD uniformity due to the strong effect of local variations in the concentration of the HP and local variations in HP conformation. The use of BCP blends with other BCPs should be more favorable from a CD uniformity perspective because this approach is much less susceptible to initial local fluctuations than HP blends because all BCPs go to the A-B interface. The coarse grained molecular dynamics simulation is well suited for comparisons such as this and can produce design rules that are needed for experimental implementation of polymer blending with BCPs to tune domain size.

Proceedings Article | 5 April 2013 Paper

Paper

Coarse grained molecular dynamics model of block copolymer directed self-assembly

Richard Lawson, Andrew Peters, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 86801Y (2013) https://doi.org/10.1117/12.2021439

KEYWORDS: Polymers, Molecular self-assembly, Polymerization, Lithography, Interfaces, Computer simulations, Systems modeling, Graphics processing units, Molecular interactions, Directed self assembly

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A model has been developed for the simulation of block copolymer (BCP) directed self-assembly (DSA) based on a coarse grained polymer model that anneals using molecular dynamics. The model uses graphics processing units (GPUs) to perform the calculations; this combined with the coarse graining means simulations times approach the speed of other more commonly used simulation techniques for BCPs. The model is unique in how it treats the pure phase blocks interactions with themselves (i.e. A-A and B-B interactions) and their interactions with each other. This allows for simulations that can potentially more accurately capture the differences between the properties of each block such as density and cohesive energy. The model is fully described and used to examine some of the issues that are unique to DSA lithographic applications of BCPs. We describe a method to calculate χ for the off-lattice MD system based on observation of the order-disorder transitions (ODT) for different degrees of polymerization N. The model is used to examine the transient, complex, non-classical morphologies that can occur through film thickness during a DSA process. During the phase separation process from a mixed initial state, the BCPs first locally phase separate to form small aggregate type structures. These aggregates then coalesce into larger features that approach the size of the equilibrium domain. These features then shift to match the guiding pattern on the underlayer followed by the slow elimination of defects. We also studied how the guiding patterns work in chemo-epitaxy DSA. The guiding patterns have a strong immediate effect on the BCP film nearest the interface and induce locally aligned self-assembly. Over time, this induced pattern tends to propagate up through the thickness of the film until the film is uniformly aligned to the guiding pattern. We also clearly see that the observed morphology at the top of the film gives no indication of the morphology through the depth, especially during the transient portions of the self-assembly process.

Proceedings Article | 5 April 2013 Paper

Paper

PS-b-PHOST as a high X block copolymers for directed self assembly: optimization of underlayer and solvent anneal processes

Nathan Jarnagin, Wei-Ming Yeh, Jing Cheng, Andrew Peters, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801X (2013) https://doi.org/10.1117/12.2021420

KEYWORDS: Polymers, Annealing, Polymerization, Scanning electron microscopy, Picosecond phenomena, Thin films, Nitrogen, Directed self assembly, Polymer thin films, Glasses

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Proceedings Article | 5 April 2013 Paper

Paper

PS-b-PHEMA: synthesis, characterization, and processing of a high X polymer for directed self-assembly lithography

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801W (2013) https://doi.org/10.1117/12.2021417

KEYWORDS: Polymers, Annealing, Lithography, FT-IR spectroscopy, Optical lithography, Etching, Magnesium, Solids, Polymerization, Directed self assembly

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Proceedings Article | 5 April 2013 Paper

Paper

PS-b-PAA as a high X polymer for directed self-assembly: a study of solvent and thermal annealing processes for PS-b-PAA

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Laren Tolbert, Clifford Henderson

Proceedings Volume 8680, 86801V (2013) https://doi.org/10.1117/12.2021414

KEYWORDS: Annealing, Polymers, Scanning electron microscopy, Picosecond phenomena, Silicon, Semiconducting wafers, Etching, Polymerization, Solids, Directed self assembly

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Proceedings Article | 26 March 2013 Paper

Paper

Effects of block copolymer polydispersity and xN on pattern line edge roughness and line width roughness from directed self-assembly of diblock copolymers

Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 8680, 868020 (2013) https://doi.org/10.1117/12.2021443

KEYWORDS: Line edge roughness, Polymers, Line width roughness, Inspection, Lithography, Neodymium, Polymerization, Edge roughness, Autoregressive models, Directed self assembly

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Proceedings Article | 16 April 2012 Paper

Paper

Investigation of high x block copolymers for directed self-asssembly: synthesis and characterization of PS-b-PHOST

Nathan Jarnagin, Jing Cheng, Andrew Peters, Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 832310 (2012) https://doi.org/10.1117/12.918081

KEYWORDS: Polymerization, Polymers, Optical lithography, Lithography, Scanning electron microscopy, Annealing, Molecular self-assembly, Directed self assembly, Glasses, FT-IR spectroscopy

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Proceedings Article | 16 April 2012 Paper

Paper

Detailed mesoscale dynamic simulation of block copolymer directed self-assembly processes: application of protracted colored noise dynamics

Andrew Peters, Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 8323, 83231T (2012) https://doi.org/10.1117/12.918077

KEYWORDS: Polymers, Computer simulations, Monte Carlo methods, Picosecond phenomena, Polymethylmethacrylate, Interfaces, Electron beam lithography, Stochastic processes, Lithography, Directed self assembly

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Proceedings Article | 16 April 2012 Paper

Paper

Directed self-assembly of poly(styrene)-block-poly(acrylic acid) copolymers for sub-20nm pitch patterning

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Nathan Jarnagin, Andrew Peters, Laren Tolbert, Clifford Henderson

Proceedings Volume 8323, 83232R (2012) https://doi.org/10.1117/12.918073

KEYWORDS: Polymers, Optical lithography, Lithography, Etching, Polymerization, Plasma etching, Annealing, Solids, Plasma, Directed self assembly

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Directed self-assembly (DSA) of block copolymers is a promising technology for extending the patterning capability of current lithographic exposure tools. For example, production of sub-40 nm pitch features using 193nm exposure technologies is conceivably possible using DSA methods without relying on time consuming, challenging, and expensive multiple patterning schemes. Significant recent work has focused on demonstration of the ability to produce large areas of regular grating structures with low numbers of defects using self-assembly of poly(styrene)-b-poly(methyl methacrylate) copolymers (PS-b-PMMA). While these recent results are promising and have shown the ability to print pitches approaching 20 nm using DSA, the ability to advance to even smaller pitches will be dependent upon the ability to develop new block copolymers with higher χ values and the associated alignment and block removal processes required to achieve successful DSA with these new materials. This paper reports on work focused on identifying higher χ block copolymers and their associated DSA processes for sub-20 nm pitch patterning. In this work, DSA using polystyrene-b-polyacid materials has been explored. Specifically, it is shown that poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) is one promising material for achieving substantially smaller pitch patterns than those possible with PS-b-PMMA while still utilizing simple hydrocarbon polymers. In fact, it is anticipated that much of the learning that has been done with the PS-b-PMMA system, such as development of highly selective plasma etch block removal procedures, can be directly leveraged or transferred to the PS-b-PAA system. Acetone vapor annealing of PS-b-PAA (M_w=16,000 g/mol with 50:50 mole ratio of PS:PAA) and its self-assembly into a lamellar morphology is demonstrated to generate a pattern pitch size (L₀) of 21 nm. The χ value for PS-b-PAA was estimated from fingerprint pattern pitch data to be approximately 0.18 which is roughly 4.5 times greater than the χ for PS-b-PMMA (_χPS-b-PMMA ~ 0.04).

Proceedings Article | 20 March 2012 Paper

Paper

Resist surface crosslinking using amine-based reactive rinses to mitagate pattern collapse in thin film lithography

Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8325, 83251X (2012) https://doi.org/10.1117/12.928876

KEYWORDS: Lithography, Capillaries, Photoresist processing, Scanning electron microscopy, Nitrogen, Deep ultraviolet, Thin films, Resistance, Chemistry, Semiconductors

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As the semiconductor industry continues to push to smaller critical dimensions, pattern collapse during lithographic processing caused by unbalanced capillary forces during the final rinse and drying process has become an important problem that can limit the practical resolution of a resist material to feature sizes larger than its intrinsic resolution limit. One of the primary modes of pattern collapse is via elastoplastic pattern deformation which is strongly related to the mechanical properties of the resist. One approach to mitigating such collapse problems is to enhance the mechanical properties of the resist features. Since such modification of resist physical properties for pattern collapse purposes is difficult to achieve through modified formulation of the resist itself (i.e. due to the complex set of requirements that a resist must satisfy and the complex set of physical and chemical phenomena that underlie the imaging processing itself), we have pursued an alternative strategy for improving the resist mechanical properties after features are developed in the film but before they are rinsed and dried. The family of techniques being developed in this work function through the use of aqueous compatible reactive rinse solutions that can be applied to developed resist features while they are wet during normal rinse processing on a track system. By applying these techniques during the rinse process, the resist features can be strengthened before they are subjected to significant capillary forces during the final drying step. In this work, the use of diamine compounds to reactively crosslink the surface of resists containing carboxylic acid groups through formation of amide bonds using carbodiimide chemistry has been explored. One advantage of this approach is that it is an aqueous process that should be easily compatible with high volume, track-based lithographic processes. Contact angle studies and x-ray photoelectron spectroscopy (XPS) were used to characterize the surface crosslinking reaction using such diamine surface rinse treatments. Pattern collapse test structures were fabricated and analyzed to measure the amount of mechanical property improvement imparted by such treatments. Application of such amine reactive rinses was found to clearly result in an improvement in the resistance of resists to pattern collapse as observed by SEM. A comparison of the critical stress at the point of pattern collapse as a function of resist feature size also clearly shows a significant improvement in mechanical resilience of resist samples processed with the reactive rinse treatment.

Proceedings Article | 20 March 2012 Paper

Paper

Application of aziridine reactive rinses in a post-development process to reduce photoresist pattern collapse

Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 8325, 83251Y (2012) https://doi.org/10.1117/12.928877

KEYWORDS: Chemistry, Nitrogen, Photoresist materials, Photoresist processing, Scanning electron microscopy, Capillaries, Electron beam lithography, Liquids, Industrial chemicals, X-rays

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One of the problems for lithographic processes at very small feature scales is pattern collapse caused by unbalanced capillary forces experienced by the photoresist patterns during the final deionized water rinse and drying process. The use of surfactants or super critical fluids to reduce collapse problems has been proposed and studied by many research groups. However, the patterns rinsed with low surface tension fluids appear in many cases to shrink or such treatments cause other feature deformations. Super critical fluid processing requires major changes to the ways in which current track systems operate and can result in swelling and deformation of the resist features as well. Instead of utilizing super critical fluids or adding surfactants to the rinse liquid, one general methodology we have pursued for alleviating such pattern collapse problems involves the actual strengthening of the resist feature itself during wet processing in the development and rinse cycle. One method we have investigated extensively is the use of post-development resist surface crosslinking reactions while the resist structures are still in their wet state, a process we term "reactive rinsing". Such reactive rinse processes have shown significant impact on improving resist pattern collapse. However, previous chemistries used for such reactive rinse processes have either: (1) been complex mixtures that potentially have long term stability problems (i.e. thus making their application in a fab environment more difficult) or (2) been specific to a certain resist types in that the chemistries react with only certain resist functional groups that may not be present in all resists of interest (e.g. some chemistries only work with phenolic resins such as those found in DUV or EUV resists). Therefore, the goal of this work has been to investigate other novel reactive rinse chemistries that are both more robust and which can function with different families of resist materials. Poly-functional aziridines offer one potential such family of compounds that could be the basis for a reactive rinse chemistry. Such aziridines are often used industrially in both aqueous and nonaqueous coatings, inks and adhesives to promote both physical and chemical properties and are known to react with carboxylic acid functional groups such as those commonly found in many 193 nm resists. The goal of this specific study was to determine if poly-functional aziridine chemistry could be used as a reactive rinse for preventing photoresist pattern collapse in 193nm type resists. Contact angle studies and x-ray photoelectron spectroscopy (XPS) were used to characterize the surface crosslinking reaction using aziridine treatments of model resists containing carboxylic acid functionality. Pattern collapse test structures were fabricated and analyzed using a PMMA/PMAA copolymer resist commonly employed for e-beam lithography. SEM studies of the resulting patterns confirm that use of multifunctional aziridine crosslinkers during a post-development process can significantly reduce pattern collapse and enable production of higher resolution features.

Proceedings Article | 16 April 2011 Paper

Paper

Developing directly photodefinable substrate guiding layers for block copolymer directed self-assembly (DSA) patterning

Jing Cheng, Richard Lawson, Wei-Ming Yeh, Laren Tolbert, Clifford Henderson

Proceedings Volume 7972, 79722I (2011) https://doi.org/10.1117/12.894702

KEYWORDS: Polymers, Lithography, Electron beam lithography, Annealing, Optical lithography, Polymethylmethacrylate, Coating, Scanning electron microscopy, Deep ultraviolet, Directed self assembly

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Directed self-assembly (DSA) of block copolymers has gained significant attention in recent years as a possible alternative for large area fabrication of future sub-30 nm lithographic patterns. To achieve this patterning, at least three critical pieces are needed: (1) a block copolymer with sufficient immiscibility of the two blocks to drive phase separation at the low molecular weights required to achieve such small phase domains, (2) a method for selectively removing one of the blocks after phase separation to achieve formation of a relief pattern, and (3) a method for producing the templated surfaces used to guide and register the phase separated patterns on the substrate of interest. Current methods for achieving the patterned substrate template, whether they are of chemoepitaxial or graphoepitaxial nature, are generally complex involving a large number of steps that are not easily applied to a variety of different substrate surfaces. For example, numerous substrates have been studied to provide neutral wettability to the styrene-methacrylate (PS-b- PMMA) block copolymers, such as random styrene-methacrylate copolymer films (PS-r-PMMA) or self-assembled monolayer (SAM) modified surfaces, which induce perpendicularly oriented morphologies for PS-b-PMMA self-assembly. In the case of chemical epitaxy processes, a layer of photoresist is generally then coated on such neutral substrate films and patterned to render commensurability to the periodicity of the PS-b-PMMA being used. The open (i.e. space) regions in the resist are then exposed to alter their chemistry, e.g. soft X-ray or oxygen plasma exposures have been used, to achieve hydrophilicity which should preferentially wet PMMA. Finally, the resist is stripped and the block copolymer is coated and assembled on the template surface. Obviously such multi-step processes would not be preferred if alternatives existed. As a step toward that goal of making DSA processes simpler, a photodefinable substrate film that can be used for PS-b-PMMA self-assembly has been developed in this work that is coated, exposed, and baked in a manner analogous to current optical photoresists. The polymer resin for this material is a form of protected poly(hydroxystyrene) that is cross-linkable. The new material is suitable for DSA processes using both solvent and thermal annealing methods. Results of PS-b-PMMA DSA on this new material will be discussed.

Proceedings Article | 16 April 2011 Paper

Paper

The effect of drying rate on pattern collapse performance in thin film lithography

Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7972, 79721Y (2011) https://doi.org/10.1117/12.895114

KEYWORDS: Photoresist materials, Scanning electron microscopy, Capillaries, Electron beam lithography, Lithography, Semiconducting wafers, Nitrogen, Photoresist developing, Liquids, Thin films

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As the semiconductor industry continues to push the limits of the lithography processes used to fabricate integrated circuits, pattern collapse during development and drying can have a substantial impact on process viability. This pattern collapse in general is caused by unbalanced capillary forces present during the drying step of the lithographic process. Significant research has focused on developing methods to reduce such capillary forces and improve the pattern collapse of photoresists. However, it appears that relatively little attention has been paid to other process dependent factors which may also significantly impact such collapse behavior. For example, another potential factor which may affect pattern collapse is the length of time during which the resist features are actually stressed during drying. As such, processes which result in different drying rates may be expected to yield different levels of pattern collapse. In this work, e-beam lithography was used to generate high resolution line-space pair arrays which contain different size spaces between a pair of adjacent lines in a model chemically amplified resist. Such line pairs present an excellent tool for studying pattern collapse and quantifying the level of stress required to cause collapse and failure of resist features. After development and rinse, such pattern collapse test structures were dried using a variety of different processes possessing a variety of different drying rates, and the impact of these different drying methods on pattern collapse was quantified. It was indeed found that drying rate has a dramatic impact on pattern collapse, with spin drying techniques performing better than most other techniques. However, it was discovered that such spin drying methods also yield a significant pattern orientation dependence of the degree of pattern collapse. Such behavior is explained in terms of additional mechanical forces caused by the centrifugal forces exerted during spin drying methods.

Proceedings Article | 16 April 2011 Paper

Paper

A study of reactive adhesion promoters and their ability to mitigate pattern collapse in thin film lithography

Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7972, 79721W (2011) https://doi.org/10.1117/12.894705

KEYWORDS: Head-mounted displays, Silicon, Electron beam lithography, Photoresist materials, Scanning electron microscopy, Lithography, Thin films, Capillaries, Ellipsometry, Standards development

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As integrated circuit fabrication continues to advance towards the 22 nm node and below, it has become clear that although line edge roughness and resolution are important, other issues such as pattern collapse must be addressed in order for technology to continue to progress. One of the primary modes of pattern collapse at small feature sizes is adhesion failure caused by loss of adhesion of the resist to the substrate during the drying process. The main forces which govern pattern collapse by adhesion failure are related to substrate/resist interactions. Significant research has been conducted to find methods for reducing capillary forces, such as use of surfactants in rinses, to reduce pattern collapse. However, the use of spin drying has also been observed to exhibit other collapse related effects that are not sensitive to such treatments. To this end, in this work a reactive adhesion promoter capable of covalently attaching to hydroxystyrene-based positive tone resist copolymers has been developed and demonstrated. A vinyl-ether-modified silane was prepared and effectively applied using a solution silanization reaction. A model hydroxystyrene-based positive tone resist was applied and subjected to post apply bake to cause reaction of the surface modifier with the photoresist to occur prior to patterning using e-beam lithography. Contact angle studies and ellipsometry were used to characterize the surface silanization reaction. Pattern collapse test structures were fabricated and analyzed after development and drying on the different surfaces to quantify the impact of the use of the covalent surface linker and compare it to more standard adhesion promoter processes such as those utilizing hexamethyldilazane (HMDS). The effect of soft bake condition on the performance of the reactive adhesion promoter has also been studied. Ultimately, the results of critical stress analysis and SEM studies of the resulting patterns confirm that use of surface priming agents that covalently attach the resist to the substrate can significantly enhance resist-substrate adhesion and dramatically reduce pattern collapse.

Proceedings Article | 16 April 2011 Paper

Paper

A comprehensive model and method for model parameterization for predicting pattern collapse behavior in photoresist nanostructures

Wei-Ming Yeh, Richard Lawson, Clifford Henderson

Proceedings Volume 7972, 79721X (2011) https://doi.org/10.1117/12.895112

KEYWORDS: Data modeling, Polymers, Polymer thin films, Photoresist materials, Capillaries, 3D modeling, Liquids, Thin films, Nanostructures, Electron beam lithography

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Proceedings Article | 2 April 2011 Paper

Paper

Development of realistic potentials for the simulation of directed self-assembly of PS-PMMA di-block copolymers

Richard Lawson, Peter Ludovice, Clifford Henderson

Proceedings Volume 7970, 79700N (2011) https://doi.org/10.1117/12.879578

KEYWORDS: Polymethylmethacrylate, Picosecond phenomena, Polymers, Lithography, Electron beam lithography, Directed self assembly, Double patterning technology, Device simulation, Computer simulations, Failure analysis

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Proceedings Article | 31 March 2010 Paper

Paper

Non-traditional resist designs using molecular resists: positive tone cross-linked and non-chemically amplified molecular resists

Richard Lawson, David Noga, Jing Cheng, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76392F (2010) https://doi.org/10.1117/12.848419

KEYWORDS: Electron beam lithography, Deep ultraviolet, Polymers, Line edge roughness, Molecules, Solids, Optical lithography, FT-IR spectroscopy, Image resolution, Lithography

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Proceedings Article | 31 March 2010 Paper

Paper

Three-dimensional mesoscale model for the simulation of LER in photoresists

Richard Lawson, Clifford Henderson

Proceedings Volume 7639, 76392G (2010) https://doi.org/10.1117/12.848415

KEYWORDS: Line edge roughness, Monte Carlo methods, 3D modeling, Diffusion, Polymers, Photoresist materials, Nanoimprint lithography, Modulation, Physics, Photoresist processing

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Proceedings Article | 31 March 2010 Paper

Paper

The use of surface modifiers to mitigate pattern collapse in thin film lithography

David Noga, Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76391H (2010) https://doi.org/10.1117/12.862008

KEYWORDS: Head-mounted displays, Photoresist materials, Electron beam lithography, Lithography, Silicon, Thin films, Molecules, Scanning electron microscopy, Standards development, Chemistry

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Proceedings Article | 31 March 2010 Paper

Paper

Thin film buckling as a method to explore the effect of reactive rinse treatments on the mechanical properties of resist thin films

Wei-Ming Yeh, David Noga, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76391I (2010) https://doi.org/10.1117/12.862009

KEYWORDS: Polymer thin films, Thin films, Polymers, Crystals, Quartz, Semiconducting wafers, Silicon, Optical lithography, Chemistry, Silicon films

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Proceedings Article | 30 March 2010 Paper

Paper

Methods to explore and prevent pattern collapse in thin film lithography

David Noga, Wei-Ming Yeh, Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76392O (2010) https://doi.org/10.1117/12.848423

KEYWORDS: Photoresist materials, Lithography, Scanning electron microscopy, Photoresist processing, Chemistry, Capillaries, Liquids, Electron beam lithography, Thin films, Line edge roughness

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Proceedings Article | 26 March 2010 Paper

Paper

Aqueous and solvent developed negative-tone molecular resists

Richard Lawson, Jing Cheng, David Noga, Todd Younkin, Laren Tolbert, Clifford Henderson

Proceedings Volume 7639, 76390O (2010) https://doi.org/10.1117/12.848414

KEYWORDS: Molecules, Electron beam lithography, Deep ultraviolet, Line edge roughness, Polymers, Polymerization, Glasses, Dewetting, Optical lithography, Scanning electron microscopy

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SPIE Journal Paper | 1 January 2010

Single-component molecular resists containing bound photoacid generator functionality

Richard Lawson, Laren Tolbert, Clifford Henderson

JM3, Vol. 9, Issue 01, 013015, (January 2010) https://doi.org/10.1117/12.10.1117/1.3280258

KEYWORDS: Line edge roughness, Glasses, Diffusion, Electron beam lithography, Line width roughness, Molecules, Polymers, Photoresist materials, Silicon, Silicon films

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SPIE Journal Paper | 1 January 2010

Mesoscale kinetic Monte Carlo simulations of molecular resists: effects of photoacid homogeneity on resolution, line-edge roughness, and sensitivity

Richard Lawson, Clifford Henderson

JM3, Vol. 9, Issue 01, 013016, (January 2010) https://doi.org/10.1117/12.10.1117/1.3358383

KEYWORDS: Line edge roughness, Diffusion, Monte Carlo methods, Optical spheres, Molecular aggregates, Performance modeling, Stochastic processes, Molecules, 3D modeling, Optical lithography

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SPIE Journal Paper | 1 October 2009

Nonionic photoacid generator behavior under high-energy exposure sources

Richard Lawson, David Noga, Laren Tolbert, Clifford Henderson

JM3, Vol. 8, Issue 04, 043010, (October 2009) https://doi.org/10.1117/12.10.1117/1.3259205

KEYWORDS: Deep ultraviolet, Absorbance, Polymers, Energy efficiency, Photons, Electron beams, Spectroscopic ellipsometry, Extreme ultraviolet, Refractive index, Absorption

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Proceedings Article | 1 April 2009 Paper

Paper

Single component molecular resists containing bound photoacid generator functionality

Richard Lawson, Laren Tolbert, Clifford Henderson

Proceedings Volume 7273, 72733C (2009) https://doi.org/10.1117/12.814426

KEYWORDS: Line edge roughness, Glasses, Diffusion, Molecules, Electron beam lithography, Line width roughness, Polymers, Silicon films, Photoresist materials, Silicon

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Proceedings Article | 1 April 2009 Paper

Paper

Understanding pattern collapse in high-resolution lithography: impact of feature width on critical stress

David Noga, Richard Lawson, Cheng-Tsung Lee, Laren Tolbert, Clifford Henderson

Proceedings Volume 7273, 727334 (2009) https://doi.org/10.1117/12.829142

KEYWORDS: Photoresist materials, Liquids, Lithography, Capillaries, Photoresist processing, Optical lithography, Head-mounted displays, Distortion, Scanning electron microscopy, Polymer thin films

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Proceedings Article | 1 April 2009 Paper

Paper

Mesoscale kinetic Monte Carlo simulations of molecular resists: the effect of PAG homogeneity on resolution, LER, and sensitivity

Richard Lawson, Clifford Henderson

Proceedings Volume 7273, 727341 (2009) https://doi.org/10.1117/12.814447

KEYWORDS: Line edge roughness, Diffusion, Monte Carlo methods, Optical spheres, Molecular aggregates, Stochastic processes, Molecules, 3D modeling, Edge roughness, Performance modeling

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Proceedings Article | 1 April 2009 Paper

Paper

Elucidating the physiochemical and lithographic behavior of ultra-thin photoresist films

Annapoorani Sundaramoorthi, Todd Younkin, Clifford Henderson

Proceedings Volume 7273, 72733V (2009) https://doi.org/10.1117/12.814410

KEYWORDS: Thin films, Temperature metrology, Photoresist materials, Glasses, Polymers, Polymer thin films, Interfaces, Lithography, Systems modeling, Thermal modeling

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As resist feature sizes and film thicknesses continue to shrink in dimension, a number of resist feature size and film thickness dependent effects are being observed in the lithographic performance of high resolution photoresists. In order to understand these phenomena, a better understanding of the physiochemical behavior of complex multi-component organic resist thin films is needed. As a first step in that direction, a series of model photoresists were studied in an effort to begin to understand the thermophysical properties of such multi-component thin films. The influence of photoacid generator (PAG) loading and PAG chemistry on the glass transition behavior using the model photoresists was studied. A thermal flow experiment was used to characterize an "apparent glass transition temperature" of the resist thin films as a function of PAG type and loading. These results were compared to traditional glass transition measurements made on the same resist compositions using differential scanning calorimetry (DSC). The two methods, namely DSC and the thermal flow measurement, yielded very different results depending on the type of PAG used. Further studies using ToF SIMS to profile the distribution of PAG in the resist thin films revealed that the two PAGs focused on in this work, a triphenylsulfonium triflate (TPS.OTF) and a triphenylsulfonium nonaflate (TPS.ONF), exhibited very different distribution behavior in resist thin films. In the case of TPS.OTF, the PAG was observed to show a depletion region near the resistsubstrate interface while the TPS.ONF PAG was relatively homogeneously distributed in the resist thin films. In the case of TPS.ONF, it was also the resist system which showed very different thermophysical behavior when comparing the glass transition temperature measured using DSC to the thermal flow temperature measurement. This work points out the fact that component distribution and thin film effects must be carefully considered in interpreting and analyzing the behavior of multi-component thin films.

Proceedings Article | 1 April 2009 Paper

Paper

Non-ionic PAG behavior under high energy exposure sources

Richard Lawson, David Noga, Laren Tolbert, Clifford Henderson

Proceedings Volume 7273, 72731R (2009) https://doi.org/10.1117/12.814459

KEYWORDS: Deep ultraviolet, Absorbance, Energy efficiency, Polymers, Photons, Electron beams, Extreme ultraviolet, Refractive index, Spectroscopic ellipsometry, Ellipsometry

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Proceedings Article | 1 April 2009 Paper

Paper

Negative-tone molecular resists based on cationic polymerization

Richard Lawson, Laren Tolbert, Todd Younkin, Clifford Henderson

Proceedings Volume 7273, 72733E (2009) https://doi.org/10.1117/12.814455

KEYWORDS: Line edge roughness, Polymerization, Electron beam lithography, Glasses, Image resolution, Diffusion, Line width roughness, Molecules, Epoxies, Scanning electron microscopy

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Proceedings Article | 15 April 2008 Paper

Paper

Effect of PAG and matrix structure on PAG acid generation behavior under UV and high-energy radiation exposure

Cheng-Tsung Lee, Mingxing Wang, Kenneth Gonsalves, Wang Yueh, Jeanette Roberts, Todd Younkin, Clifford Henderson

Proceedings Volume 6923, 69232F (2008) https://doi.org/10.1117/12.782634

KEYWORDS: Polymers, Polymer thin films, Ionization, Picosecond phenomena, Deep ultraviolet, Absorption, Photoresist materials, Molecules, Matrices, Photolysis

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Chemically amplified resists (CAR) have successfully facilitated the development of deep ultra-violet (DUV) and 193 nm lithography techniques for more than two decades due to their acid-catalyzed deprotection scheme that enhances their photospeed. This acid-catalyzed mechanism provides a method for amplifying the initial chemical reactions caused by interaction of radiation with the resist film, thus making each interaction event between radiation and resist more productive. However, when switching from low energy photolysis to high energy radiolysis, changes in the manner in which the radiation interacts with the resist material can alter the acid generation efficiency and mechanism of PAG excitation. In high energy radiation cases where the radiation energy exceeds the ionization potential of the PAG and the polymer resin, the radiation absorption in the resist film becomes non-selective. The ratio of PAG excited by direct excitation as compared to polymer or matrix sensitization pathways can shift heavily in favor of matrix sensitization in such high energy exposure cases. Such sensitization pathways may become a potential method for enhancing resist sensitivity under high energy radiation through careful selection of matrix and PAG materials. A better understanding and study the efficiency of acid generation through direct and indirect PAG excitation pathways and the effect of PAG and matrix structure on these pathways would be extremely valuable for the design of future high sensitivity resist materials. In this work, the acid generation of typical ionic (onium salt) and non-ionic PAGs under DUV (248 nm) and electron-beam exposure in polymer film have been studied. The effect of PAG type and structure on its acid generation under photolysis and radiolysis has been determined. The effect of polymer resin structure on PAG photoacid generation under photolysis and radiolysis has also been investigated. Concepts for PAG and polymer design for producing enhanced sensitivity resists for excitational and ionizational exposure is discussed.

Proceedings Article | 27 March 2008 Paper

Paper

Single molecule chemically amplified resists based on ionic and non-ionic PAGs

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69230K (2008) https://doi.org/10.1117/12.773570

KEYWORDS: Molecules, Line edge roughness, Glasses, Diffusion, Image resolution, Deep ultraviolet, Polymers, Extreme ultraviolet lithography, Etching, Chemically amplified resists

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Proceedings Article | 26 March 2008 Paper

Paper

Synthesis and properties of new anionic photoacid generators bound polymer resists for e-beam and EUV lithography

Mingxing Wang, Cheng-Tsung Lee, Clifford Henderson, Wang Yueh, Jeanette Roberts, Kenneth Gonsalves

Proceedings Volume 6923, 692312 (2008) https://doi.org/10.1117/12.769004

KEYWORDS: Polymers, Absorption, Extreme ultraviolet lithography, Deep ultraviolet, Lithography, Line edge roughness, Polymer thin films, NOx, Silicon, Scanning electron microscopy

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Proceedings Article | 26 March 2008 Paper

Paper

Mesoscale simulation of molecular glass photoresists: effect of PAG loading and acid diffusion coefficient

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69230Q (2008) https://doi.org/10.1117/12.774619

KEYWORDS: Line edge roughness, Diffusion, Molecules, Glasses, Critical dimension metrology, Polymers, Photoresist materials, Chemically amplified resists, Lithography, Solid modeling

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Proceedings Article | 26 March 2008 Paper

Paper

A new technique for studying photo-acid generator chemistry and physics in polymer films using on-wafer ellipsometry and acid-sensitive dyes

Cheng-Tsung Lee, Wang Yueh, Jeanette Roberts, Todd Younkin, Clifford Henderson

Proceedings Volume 6923, 692316 (2008) https://doi.org/10.1117/12.773393

KEYWORDS: Polymers, Polymer thin films, Polymethylmethacrylate, Absorbance, Ellipsometry, Lithography, Deep ultraviolet, Photolysis, Absorption, Chemistry

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Chemically amplified resists (CARs) are likely to continue to be the main resist materials platform for next generation lithography using shorter wavelength and higher energy radiation sources, such as extreme ultra-violet (EUV) and electron-beam (EB) lithography, to pattern features at and below the 32 nm technology node. As the cost of generating and manipulating high energy radiation in these techniques increases dramatically, photoacid generators (PAGs) with high sensitivities to these exposure sources are required to efficiently utilize such radiation and maintain high lithography tool throughputs. On the other hand, the high energy radiation used in current and next generation lithography tools can increasingly interact non-selectively with the PAG and polymer resin. Photoacid generation from PAG sensitization pathways involving the photoresist resin (e.g. polymer) becomes another potential route for boosting the photospeed of CARs if the PAG and matrix resin chemistry is selected properly. In this work, a fast, convenient, and material saving method which can measure the acid generation rate and yield under photolysis and radiolysis, as well as determine the efficiency of acid generation through direct PAG excitation and indirect PAG sensitization pathways has been developed. This method utilizes on-wafer ellipsometry to determine the absorption of protonated Courmarin 6 (C6) dye, which is incorporated into the polymer resin as a proton indicator. In this work, triphenylsulfonium triflate PAG is used in two different matrix resins, poly(methyl methacrylate) and poly(hydroxystyrene), to illustrate this point that matrix sensitization of the PAG can be important and can be studied using the method developed in this work. This study serves as the starting point for building the structure property relationships needed for intelligent PAG and matrix design to optimize exposure energy utilization in CARs. The validity of this new analytical method is verified by comparing our results in selected PAG-polymer combinations with results obtained from previous studies using different techniques. The potential measurement errors possible when using dye as the proton indicator in a solid-state medium, such as the probability of proton-dye contact and acid generation through dye radiation absorption and sensitization of the PAG, are also analyzed and discussed in this paper.

Proceedings Article | 26 March 2008 Paper

Paper

Water-developable negative-tone single-molecule resists: high-sensitivity nonchemically amplified resists

Richard Lawson, Cheng-Tsung Lee, Wang Yueh, Laren Tolbert, Clifford Henderson

Proceedings Volume 6923, 69231I (2008) https://doi.org/10.1117/12.773188

KEYWORDS: Molecules, Image resolution, Imaging systems, Line edge roughness, Electron beam lithography, Deep ultraviolet, Chemically amplified resists, Image processing, Switching, Diffusion

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Proceedings Article | 12 April 2007 Paper

Paper

Novel photodefinable low-k dielectric polymers based on polybenzoxazines

Michael Romeo, Kazuhiro Yamanaka, Kazuhiko Maeda, Clifford Henderson

Proceedings Volume 6519, 65191K (2007) https://doi.org/10.1117/12.713011

KEYWORDS: Polymers, Dielectrics, Chlorine, Glasses, Microelectronics, Absorption, Packaging, FT-IR spectroscopy, Water, Argon

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The development of spin-on photodefinable dielectrics for use in microelectronic device fabrication and packaging has traditionally focused mainly on the use of soluble polymer precursors because the desired final dielectric polymer structure is generally insoluble in any appropriate casting solvent. One major drawback to this approach however is that high temperature processes (often >300 °C) after imaging and development are generally required to convert the imaged precursor polymer into the desired low dielectric constant material. These high processing temperatures make such materials impractical for a variety of applications. The goal of the work reported in this paper was to overcome this problem by developing new low dielectric constant polymers that can be formulated into photodefinable materials and processed at lower temperatures. In this work the use of a novel hexafluoroisopropanol (HFA)-substituted diamine to synthesize novel polybenzoxazines is reported. Whereas polybenzoxazoles form a five membered ring by situating an alcohol ortho to an amide, the benzoxazine rings in the polymer backbone described in this work are formed by the dehydration of a hexafluoroalcohol (HFA) group situated ortho to the amide to form a six membered ring. Of this general class of new polybenzoxazine amide alcohol precursor polymers, it will be shown that selected polymers exhibit good solubility in developer solutions and can be formulated into photosensitive compositions by addition of a DNQ inhibitor. Polybenzoxazine film properties including dielectric constant, thermal expansion coefficient, glass transition temperature, water absorption and dissolution rate have been measured. In particular, the dielectric constant for polybenzoxazine is reported to be as low as 2.2. In contrast to polybenzoxazoles which are known to cyclize at temperatures well above 280 °C, the new polymers reported here can be cyclized at temperatures as low as 210 °C. This significantly lower thermal cyclization temperature greatly alleviates many problems with other photodefinable dielectric polymers such as thermal stress build-up during curing and also allows these materials to be integrated with a wider variety of materials that would not survive the significantly higher processing temperature required with most current polyimides and polybenzoxazoles.

SPIE Journal Paper | 1 April 2007

Nanoscale thermal lithography by local polymer decomposition using a heated atomic force microscope cantilever tip

Yueming Hua, Shubham Saxena, Clifford Henderson, William King

JM3, Vol. 6, Issue 02, 023012, (April 2007) https://doi.org/10.1117/12.10.1117/1.2743374

KEYWORDS: Polymers, Polymer thin films, Lithography, Optical lithography, Atomic force microscope, Metrology, Scanning probe lithography, Silicon, In situ metrology, Silicon films

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Proceedings Article | 31 March 2007 Paper

Paper

A novel top surface imaging approach utilizing direct-area selective atomic layer deposition of hardmasks

Ashwini Sinha, Dennis Hess, Clifford Henderson

Proceedings Volume 6519, 65191J (2007) https://doi.org/10.1117/12.712458

KEYWORDS: Atomic layer deposition, Polymers, Etching, Polymer thin films, Plasma etching, Silicon, Plasma, Metals, Oxides, Oxygen

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Proceedings Article | 23 March 2007 Paper

Paper

Photosensitivity and line-edge roughness of novel polymer-bound PAG photoresists

Cheng-Tsung Lee, Mingxing Wang, Nathan Jarnagin, Kenneth Gonsalves, Jeanette Roberts, Wang Yueh, Clifford Henderson

Proceedings Volume 6519, 65191E (2007) https://doi.org/10.1117/12.713369

KEYWORDS: Polymers, Line edge roughness, Lithography, Analog electronics, Diffusion, Image resolution, Polymer thin films, Silicon, Photoresist materials, Semiconducting wafers

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Substantially improved photoresist material designs, which can provide higher photosensitivity and precise critical dimension and edge roughness control, will be required to enable the application of next generation lithography technology to the production of future sub-65 nm node IC device generations. The development and characterization of novel material platforms that solve the aforementioned basic problems with chemically amplified resists (CARs) is essential and is already one of the major subjects of modern lithography research. In that regard, we have pursued development of a variety of 193 nm and EUV CARs that contain photoacid generator (PAG) units covalently bonded directly to the resin polymer backbone. However, the detailed structure-property relationships that result from this direct attachment of the PAG functional group to the polymer have previously not yet been rigorously characterized. In this work, the lithographic properties of a polymer-bound PAG CAR (GBLMA-co-EAMA-co-F4-MBS.TPS) and its blended-PAG analog resist (GBLMA-co-EAMA blend F4-IBBS.TPS) were studied and compared. The direct incorporation of PAG functionality into the resist polymer, where the resulting photoacid remains bound to the polymer, showed improved photosensitivity, resolution, and lower LER as compared with the analogous blended-PAG resist. The improved resolution and LER were expected due to the restricted photoacid diffusion and uniform PAG distribution provided by direct incorporation of the PAG into the polymer backbone to make a single-component resist material. The ability to load higher levels of PAG into the resist provided by this PAG incorporation into the polymer, as compared to the low PAG concentrations attainable by traditional blending approaches, overcomes the sensitivity loss that should result from reduction in photoacid diffusivity and concomitant smaller acid-catalytic chain lengths. In fact, the polymer-bound PAG resist achieves a faster photospeed than the blended-PAG analog material under DUV radiation in the case of the materials reported here while still providing all of the aforementioned improvements such as the improved line edge roughness.

Proceedings Article | 23 March 2007 Paper

Paper

Novel anionic photoacid generator (PAGs) and photoresist for sub-50-nm patterning by EUVL and EBL

Mingxing Wang, Cheng-Tsung Lee, Clifford Henderson, Wang Yueh, Jeanette Roberts, Kenneth Gonsalves

Proceedings Volume 6519, 65191F (2007) https://doi.org/10.1117/12.712143

KEYWORDS: Polymers, Extreme ultraviolet lithography, Line edge roughness, Extreme ultraviolet, Photoresist materials, Electron beam lithography, Lithography, Polymerization, Image processing, Optical lithography

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Proceedings Article | 21 March 2007 Paper

Paper

Molecular glass photoresists containing photoacid generator functionality: a route to a single-molecule photoresist

Richard Lawson, Cheng-Tsung Lee, Robert Whetsell, Wang Yueh, Jeanette Roberts, Laren Tolbert, Clifford Henderson

Proceedings Volume 6519, 65191N (2007) https://doi.org/10.1117/12.712928

KEYWORDS: Glasses, Line edge roughness, Etching, Polymers, Photoresist materials, Deep ultraviolet, Extreme ultraviolet lithography, Diffusion, Molecules, Reactive ion etching

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Proceedings Article | 21 March 2007 Paper

Paper

Direct three-dimensional nanoscale thermal lithography at high speeds using heated atomic-force microscope cantilevers

Yueming Hua, Shubham Saxena, Jung Lee, William King, Clifford Henderson

Proceedings Volume 6517, 65171L (2007) https://doi.org/10.1117/12.713374

KEYWORDS: Polymers, Polymer thin films, Lithography, Modulation, Electron beam lithography, Atomic force microscopy, Atomic force microscope, Optical lithography, Manufacturing, Silicon

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Proceedings Article | 31 March 2006 Paper

Paper

Nanolithography in thermally sacrificial polymers using nanoscale thermal probes

Yueming Hua, Shubham Saxena, William King, Clifford Henderson

Proceedings Volume 6153, 61531G (2006) https://doi.org/10.1117/12.661803

KEYWORDS: Polymers, Lithography, Optical lithography, Nanolithography, Crystals, Thin films, Atomic force microscope, Glasses, Resistance, Atomic force microscopy

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Proceedings Article | 31 March 2006 Paper

Paper

Fundamental studies of the properties of photoresists based on resins containing polymer-bound photoacid generators

Cheng-Tsung Lee, Nathan Jarnagin, Mingxing Wang, Kenneth Gonsalves, Jeanette Robert, Wang Yueh, Clifford Henderson

Proceedings Volume 6153, 61532E (2006) https://doi.org/10.1117/12.663410

KEYWORDS: Polymers, Data modeling, Diffusion, Photoresist materials, FT-IR spectroscopy, Statistical modeling, Molecules, Extreme ultraviolet lithography, Polymer thin films, Reflectivity

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Proceedings Article | 29 March 2006 Paper

Paper

Novel low-dielectric constant photodefinable polyimides for low-temperature polymer processing

Kazuhiro Yamanaka, Michael Romeo, Kazuhiko Maeda, Clifford Henderson

Proceedings Volume 6153, 61531H (2006) https://doi.org/10.1117/12.655600

KEYWORDS: Polymers, Dielectrics, Fourier transforms, Absorption, Polymer thin films, Silicon, Crystals, Temperature metrology, Capacitors, Hydrogen

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Current photosensitive polyimide formulations that can be developed in aqueous alkaline developers are based on the use of either (1) soluble poly(amic acid) precursor polymers or (2) polyimides functionalized with hydrophilic groups (e.g. phenol). The use of poly(amic acid) polymers requires the subsequent high temperature thermal cyclization of the polymer after imaging to produce the desired polyimide which can prevent ue of such materials in many applications. However, the use of pre-imidized poliyimides by imparting solubility with hydrophilic groups also is problematic since the presence of such groups in the polymer generally degrades the dielectric constant and water uptake performance of such materials. The goal of the work in this paper was to overcome these problems by developing new low dielectric constant polyimides that can be formulated into photo-definable materials and processed at low temperatures. In this work the use of a novel hexafluoroisopropanol (HFA)-substituted diamine to synthesize novel poly(amic-acid) and polyimide polymers is reported. The addition of HFA to the polymers is shown to produce polyimides which are soluble in both common casting solvents and 0.26 N TMAH alkaline developers. A photosentitive polyimide composition based on formulation of the HFA-subtituted polyimide with 20 wt% of a DNQ inhibitor is shown to produce high resolution patterns with a sensitivity of 170 mJ/cm² and a contrast of 1.32 using I-line exposure. The HFA groups in the polymers are contained on a substituent group attached to the main chain by an ester linkage. It is shown that these HFA-substituent side-groups can be easily removed from the polymer after development of the patterned image by thermal treatment of the polymer at temperatures above 280 ^oC. The cleavage of the HFA side groups produces a polymer which does not swell and is insoluble in aqueous alkaline developers. Polyimide film properties including dissolution rate, dielectric constant, thermal expansion coefficient (CTE), water absorption have been measured and are shown to be strongly dependent on the presence of the HFA side groups. In particular, the dielectric constant of the polyimide is shown to decrease dramatically from 3.20 to 2.60 after thermal cleavage of the HFA side groups using a thermal cure at 350 ^oC for 30 minutes. In general, the strategy of using solubility enhancing functional groups that can be cleaved from the polymer during or after imaging and development appears to be a very promising strategy for developing photo-definable low dielectric constant polymers that can be processed at low temperatures.

Proceedings Article | 4 May 2005 Paper

Paper

Effect of film composition on the performance of interdigitated electrode methods used for chemically amplified photoresist characterization: methods for analyzing photoresist materials containing base quencher

Cody Berger, Clifford Henderson

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.607437

KEYWORDS: Capacitance, Polymers, Electrodes, Polymer thin films, Photoresist materials, Sensors, Molecules, Dielectrics, Chemical analysis, Data modeling

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Proceedings Article | 4 May 2005 Paper

Paper

Area selective atomic layer deposition: use of lithographically defined polymer masking layers for the deposition of titanium dioxide

Ashwini Sinha, Dennis Hess, Clifford Henderson

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.598856

KEYWORDS: Polymers, Atomic layer deposition, Polymer thin films, Polymethylmethacrylate, Titanium, Self-assembled monolayers, Silicon, Metals, Diffusion, Chemical vapor deposition

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Proceedings Article | 4 May 2005 Paper

Paper

The effect of film thickness on the dissolution rate and hydrogen bonding behavior of photoresist polymer thin films

Lovejeet Singh, Peter Ludovice, Clifford Henderson

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.600100

KEYWORDS: Polymers, Hydrogen, Polymer thin films, Crystals, Photoresist materials, FT-IR spectroscopy, Silicon films, Quartz, Liquid crystals, Silicon

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Proceedings Article | 4 May 2005 Paper

Paper

Equilibrium water uptake and diffusion behavior in model polynorbornene photoresist polymers

Trevor Hoskins, Paul Roman, Peter Ludovice, Clifford Henderson

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.607434

KEYWORDS: Polymers, Diffusion, Photoresist materials, Crystals, Liquids, Hydrogen, Water, Humidity, Immersion lithography, Molecules

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Proceedings Article | 4 May 2005 Paper

Paper

Characterization of property variation in ultra-thin polymer films from molecular simulation

Lovejeet Singh, Clifford Henderson, Peter Ludovice

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.607435

KEYWORDS: Polymers, Polymer thin films, Chemical species, Molecules, Glasses, Thin films, Computer simulations, Diffusion, Carbon, Optical lithography

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Proceedings Article | 4 May 2005 Paper

Paper

Material design and evaluation of nanocomposite resist for next generation lithography

Kenneth Gonsalves, Muthiah Thiyagarajan, Kim Dean, Patricia Santiago, L. Rendon, Augustin Jeyakumar, Clifford Henderson

Proceedings Volume 5753, (2005) https://doi.org/10.1117/12.597308

KEYWORDS: Etching, Polymers, Plasma etching, Nanocomposites, Lithography, Plasma, Reactive ion etching, Electron beam lithography, Resistance, Silicon films

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Proceedings Article | 7 March 2005 Paper

Paper

Integrated planar lightwave bio/chem OEIC sensors on Si CMOS circuits

Nan Jokerst, Martin Brooke, Sang-Yeon Cho, Mikkel Thomas, Jeffrey Lillie, Daeik Kim, Stephen Ralph, Karla Dennis, Benita Comeau, Cliff Henderson

Proceedings Volume 5730, (2005) https://doi.org/10.1117/12.592771

KEYWORDS: Sensors, Silicon, Thin films, CMOS sensors, Waveguides, Thin film devices, System integration, Optoelectronic devices, Integrated optics, Etching

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Proceedings Article | 20 May 2004 Paper

Paper

Microsystems manufacturing via embossing of photodefinable thermally sacrificial materials

Celesta White, Travis Anderson, Clifford Henderson, Harry Rowland, William King

Proceedings Volume 5374, (2004) https://doi.org/10.1117/12.536277

KEYWORDS: Polymers, Silicon, Microfluidics, Manufacturing, Lithography, Microelectromechanical systems, Scanning electron microscopy, Semiconducting wafers, Etching, Microsystems

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Substantial recent interest in microelectronics manufacturing has motivated significant work on non-traditional processes such as embossing-based lithography. This work has been generally limited to manufacturing conventional microelectronics, producing two dimensional patterned surfaces and structures. To date, little work has been done to produce microelectromechanical systems (MEMS), which can require production of complex three-dimensional and possibly free standing structures. This paper reports a novel method for manufacturing three-dimensional microstructures that can be freely standing and/or fully released. The method involves the use of thermally sacrificial polymers, i.e. materials that can be cleanly decomposed to gaseous products upon heating at elevated temperatures. Such sacrificial polymers can be directly embossed and subsequently overcoated with a variety of materials including other polymers, dielectrics, semiconductors, and metals. Following the deposition of the overcoat layer, further processing can be performed on the overcoat layer (e.g. selective etching or deposition of additional materials). Finally, the entire structure is heated to the decomposition temperature of the sacrificial polymer which results in the “dry” removal of the sacrificial layer, thus releasing the desired structures. The various sacrificial materials that have been investigated are polynorbornenes and polycarbonates, and the overlayer materials include polyimides, silicon oxide, and metals. This paper discusses the various properties of these sacrificial materials, the printing and processing conditions for these materials, and the use of this method for the fabrication of a MEMS based microfluidic system with free standing and suspended obstructions. This novel manufacturing technique meets the needs of MEMS manufacturing in that it can produce three dimensional and free standing microstructures. It permits the fabrication of devices and systems in only a few process steps that would otherwise be either substantially more complicated or impossible to achieve. This process of coating, embossing, and overcoating can also be repeated to build-up complex multi-layered structures.

Proceedings Article | 14 May 2004 Paper

Paper

Photosensitive co-polycarbonates for use as sacrificial materials in the fabrication of microfluidic and microelectromechanical devices

Celesta White, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.534332

KEYWORDS: Polymers, Microfluidics, Microelectromechanical systems, Optical lithography, Crystals, Fabrication, Promethium, Glasses, Semiconducting wafers, Lithography

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In the rapidly growing field of microfluidics, there is a tremendous need for alternative fabrication processes and for simple methods to integrate higher levels of functionality into microfluidic systems (i.e., fully-integrated, multi-level fluidic systems with functional valves, pumping systems, and other MEMS components). A fabrication technique recently developed at Georgia Tech involving thermally sacrificial polymeric materials allows for these innovations. In this method, which is completely compatible with traditional IC fabrication processes, thermally sacrificial polymers are coated onto a substrate and patterned into the shape of the desired channels and devices. These polymeric structures are then overcoated with a permanent structural material such as an inorganic glass or polymer. These steps can be repeated to produce complex, three-dimensional systems. Finally, the completed device structure is heated to the decomposition temperature of the sacrificial polymer which volatilizes to leave behind the desired open-channeled structures. These same materials and techniques can also be applied to the fabrication of a variety of microelectromechanical system components, including suspended membrane structures and cantilevers, that are integrated directly with IC devices on a common substrate. This process was first developed using functionalized polynorbornenes that decompose at temperatures near 425°C. In order to make this approach compatible with a wider range of substrates and structural materials, polymers with lower decomposition temperatures were desired, and polycarbonates were identified as a class of polymers with decomposition temperatures in the desired range (200-300°C). In addition, utilizing a polymer that can be patterned directly by conventional lithography greatly simplifies the fabrication process. By exploiting the acid-catalyzed thermolysis of polycarbonates, low decomposition temperature, photosensitive sacrificial polymers can be developed using mixtures of photoacid generators [PAG] and polycarbonates. Preliminary studies of several different polycarbonates, both photosensitive and non-photosensitive, have shown promising results, but optimization of these materials will be required to realize their full potential as sacrificial materials for use in microsystems manufacturing. The imaging characteristics of these polycarbonates vary greatly with the differing polymer thermal properties and polymer crystallinity, which are directly related to the polymer structure. A comparison of several new secondary and tertiary co-polycarbonates and their ability to maintain feature integrity during photolithography are presented.

Proceedings Article | 14 May 2004 Paper

Paper

Improved chemically amplified photoresist characterization using interdigitated electrode sensors: photoacid diffusivity measurements

Cody Berger, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536218

KEYWORDS: Diffusion, Humidity, Resistance, Electrodes, Polymers, Photoresist materials, Sensors, Dielectric spectroscopy, Polymer thin films, Ions

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Proceedings Article | 14 May 2004 Paper

Paper

Effect of nanoscale confinement on the diffusion behavior of photoresist polymer thin films

Lovejeet Singh, Peter Ludovice, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.535333

KEYWORDS: Diffusion, Polymers, Polymer thin films, Crystals, Photoresist materials, Quartz, Molecules, Humidity, Thin films, Electron beam lithography

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Proceedings Article | 14 May 2004 Paper

Paper

Enhancing the electron beam sensitivity of hydrogen silsesquioxane (HSQ)

Augustin Jeyakumar, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536245

KEYWORDS: Electron beams, Electron beam lithography, Hydrogen, Silicon, Lithography, Silicon films, Coating, Printing, Photomasks, Molecules

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Proceedings Article | 14 May 2004 Paper

Paper

Effect of film thickness on the dissolution rate behavior of photoresist polymer thin films

Lovejeet Singh, Peter Ludovice, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536205

KEYWORDS: Polymers, Polymer thin films, Crystals, Photoresist materials, Thin films, Quartz, Liquid crystals, Lithography, Data conversion, Diffusion

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Fabrication of future nanoscale electronic devices will likely require the use of ultra-thin resist films. It has been observed that film thickness, molecular weight, and substrate interactions can significantly affect the thermophysical properties of polymer thin films such as the glass transition temperature and coefficient of thermal expansion. Recently, film thickness has been reported to have a dramatic impact on the diffusion coefficient of small molecules in polymer ultra-thin films. Both of these factors, changes in either the polymer film thermophysical properties or diffusion behavior, can potentially have an impact of the lithographic performance of polymer thin film photoresists. As an extension to this previous work, it is desirable to understand the influence of film thickness on a variety of other lithographically important polymer properties. Dissolution rate is one such important physical property for photoresist polymer thin films that is of particular importance to the microelectronics industry. Simulation of lithographic processes relies to a great extent on knowledge of the dissolution or development behavior of photoresist thin films. Resist contrast is also known to be strongly affected by the dissolution behavior of the resist matrix polymer. So far, the possibility of film thickness significantly affecting the dissolution behavior of thin photoresist films has generally been ignored. This paper reports on work focused on determining the effect of film thickness on the dissolution behavior of a variety of resist polymers including novolac, polyhydroxystyrene (PHOST), and bis-trifluoromethyl carbinol substitute polynorbornene (HFAPNB). In the present work, Quartz Crystal Microbalance (QCM) methods were used to determine the dissolution rate of polymer thin films for thicknesses ranging from approximately 1 μm to 100 nm. It was observed that both poly(hydroxystyrene) (PHOST) and bis-trifluoromethyl carbinol substituted polynorbornene (HFAPNB) exhibit strong surface acceleration behavior as compared to the classic surface inhibition that has been extensively studied in novolac polymers. Most importantly, the dissolution rate of PHOST and HFAPNB thin films was found to depend strongly on the thickness of the polymer film for film thicknesses below a critical thickness value.

Proceedings Article | 14 May 2004 Paper

Paper

Effect of photoacid generator additives on the dissolution behavior of bis-trifluoromethyl carbinol substituted polynorbornene

Trevor Hoskins, Cody Berger, Peter Ludovice, Clifford Henderson, Larry Seger, Chun Chang, Larry Rhodes

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536264

KEYWORDS: Polymers, Hydrogen, Solids, Photoresist materials, FT-IR spectroscopy, Ultraviolet radiation, Optical lithography, Lithography, Photoresist developing, Molecules

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Proceedings Article | 14 May 2004 Paper

Paper

Chemically amplified photoresist characterization using interdigitated electrodes: an improved method for determining the Dill C parameter

Cody Berger, Clifford Henderson

Proceedings Volume 5376, (2004) https://doi.org/10.1117/12.536243

KEYWORDS: Capacitance, Data modeling, Polymers, Electrodes, Photoresist materials, Polymer thin films, Dielectrics, Sensors, Coating, Silicon

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Proceedings Article | 12 June 2003 Paper

Paper

Influence of film thickness, molecular weight, and substrate on the physical properties of photoresist polymer thin films

Lovejeet Singh, Peter Ludovice, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485134

KEYWORDS: Polymer thin films, Silicon films, Polymers, Polymethylmethacrylate, Silicon, Glasses, Head-mounted displays, Oxides, Temperature metrology, Thin films

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Proceedings Article | 12 June 2003 Paper

Paper

A comparative study between organic and inorganic resists in electron beam lithography using Monte Carlo simulations

Augustin Jeyakumar, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485129

KEYWORDS: Polymethylmethacrylate, Scattering, Chemical species, Titanium, Electron beam lithography, Monte Carlo methods, Electron beams, Silicon, Molecules, Laser scattering

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A Monte Carlo study has been performed in order to understand the differences in exposure behavior between organic and inorganic electron beam resists. Typically inorganic resists constitute high atomic number species (Z>10) and are of higher density as compared to traditional organic resists such as acrylates. In this work, the consequences of tethering a high atomic number species such as a silicon or titanium atom onto a PMMA molecule on the electron beam energy deposition in the material have been investigated. The addition of these atoms increases the density of the hypothetical film and therefore the number of elastic and inelastic collisions suffered by an incident electron. The larger electron shell density associated with these high atomic number species more effectively shields the nucleus resulting in a larger average elastic scattering angle but the average inelastic scattering angle remains unaffected. The average radial and depth distance traveled by an incident electron decreases with increasing atomic number of the species tethered to the PMMA molecule. The radial and energy distribution of incident electrons in PMMA, HSQ, and a Titanium based metal-organic precursor film have also been compared. At low accelerating potentials, the broadening of the point source electron beam becomes larger with the increasing atomic number of the atoms in the resist material. However, at high accelerating potentials where the average depth distance traveled into the film increases, the point source electron beam broadening is essentially the same for both organic and inorganic films for thin films. Eventually, at large film thicknesses, the radial spread of incident electrons becomes broader in the inorganic films as a consequence of higher density and larger scattering atoms. Also, as a consequence of a larger number of collisions, the absorbed energy density in inorganic films increases, indicating that these materials will more efficiently capture electron beam energy as compared to traditional organic materials.

Proceedings Article | 12 June 2003 Paper

Paper

Dissolution behavior of bis-trifluoromethyl-carbinol-substituted polynorbornenes

Trevor Hoskins, Won Jae Chung, Peter Ludovice, Clifford Henderson, Larry Seger, Larry Rhodes, Robert Shick

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485145

KEYWORDS: Polymers, Hydrogen, Polymer thin films, FT-IR spectroscopy, Solids, Lithography, Photoresist materials, Palladium, X-ray diffraction, Molecules

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Proceedings Article | 12 June 2003 Paper

Paper

Equilibrium sorption and rate of diffusion of water into photoresist thin films

Cody Berger, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485079

KEYWORDS: Polymers, Humidity, Dielectrics, Diffusion, Capacitance, Crystals, Electrodes, Photoresist materials, Thin films, Quartz

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Proceedings Article | 12 June 2003 Paper

Paper

Nanocomposite resist for low-voltage electron beam lithography (LVEBL)

Mohammad Azam Ali, Kenneth Gonsalves, Ankur Agrawal, Augustin Jeyakumar, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.483740

KEYWORDS: Etching, Electron beam lithography, Electron beams, Polymers, Nanocomposites, Lithography, Resistance, Silicon, Plasma etching, Plasma

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Proceedings Article | 12 June 2003 Paper

Paper

Hybrid bilayer imaging approach using single-component metal-organic precursors for high-resolution electron beam lithography

Augustin Jeyakumar, Clifford Henderson, Paul Roman, Seigi Suh

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485133

KEYWORDS: Etching, Electron beam lithography, Electron beams, Plasmas, Silicon films, Titanium, Silica, Plasma etching, Silicon, Photomasks

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Proceedings Article | 12 June 2003 Paper

Paper

Investigation of surface inhibition and its effects on the lithographic performance of polysulfone-novolac electron beam resists

Ankur Agrawal, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485137

KEYWORDS: Lithography, Sulfur, Electron beam lithography, Electron beams, Temperature metrology, Surface roughness, Interfaces, X-rays, Polymers, Photoemission spectroscopy

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Proceedings Article | 12 June 2003 Paper

Paper

Measurement of photoacid generation kinetics in photoresist thin films via capacitance techniques

Cody Berger, Clifford Henderson

Proceedings Volume 5039, (2003) https://doi.org/10.1117/12.485081

KEYWORDS: Capacitance, Electrodes, Polymers, Photoresist materials, Absorbance, Dielectrics, Sensors, Coating, Chemically amplified resists, Data modeling

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Proceedings Article | 2 June 2003 Paper

Paper

Monitoring the dissolution rate of photoresist thin films via multiwavelength interferometry

Ankur Agrawal, Clifford Henderson

Proceedings Volume 5038, (2003) https://doi.org/10.1117/12.485006

KEYWORDS: Thin films, Data analysis, Silicon films, Photoresist materials, Interferometry, Reflectivity, Silicon, Photoresist developing, Interfaces, Oxides

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Dissolution rate monitors (DRMs) and related techniques have been used for a number of years to study the dissolution behavior of photoresist materials in detail. Due to the relative difficulty in obtaining commercial DRM instruments, crude methods for measuring dissolution rates such as the (formula availble in paper) have been developed. In this method, the resist-coated substrate is immersed in a developer solution for a fixed development time, removed and dried, and the remaining film thickness is measured. The dissolution rate information for the resist is then calculated from the slope of the resist thickness versus development time data. This method is simple and can easily be used in a fab environment, but it suffers from a number of limitations. For example, this method is very inaccurate for resists that develop very quickly (< 20 seconds) such as many modern chemically amplified resists. Such quick development times are often crucial in exploring the full behavior of a resist. A much better method for measuring the dissolution behavior of photoresist films is to use interferometric methods such as those suggested originally by Dill and coworkers. In this work, an extremely flexible and simple instrument based on inexpensive, commercially available, PC card spectrometers will be presented that can be used quite robustly in both fab and laboratory environments for measuring the dissolution behavior of photoresist films. The hardware required in order to construct such a simple apparatus will be discussed along with various experimental configurations that are appropriate for different measurement tasks. Thin film thickness estimation using the DRM can be done using either single wavelength versus time interferometry data (plot of reflected light intensity versus development time) or the complete multiwavelength spectra obtained from a spectroscopic reflectometry system. Film thickness estimation using single wavelength data analysis is good for films that: develop completely to the substrate, do not swell during the development process, and do not develop very fast (i.e., > 100 nm/s). Hence for films that either have very long development times (typically very thick films of the order of ~ 5μm), films that have very short development times (usually with dissolution rates exceeding 100 nm/s), or films that swell during development, film thickness determination using the multiwavelength reflectance spectra is the best solution. With this motivation, a multiwavelength interferometric data analysis software (MIDAS) has been developed in this work that can robustly perform both single and multiwavelength DRM data analysis. It has been found to be very useful in analyzing thin film dissolution data with dissolution rates exceeding 400 nm/s. Another useful application has been to measure swelling in the processing of photoresists and other polymer thin films. For example, such resist swelling appears to be an issue in the case of resists or other polymers developed or cleaned using high pressure CO2. The basic approaches and algorithms used for thin film thickness/rate determination in MIDAS will be discussed. The advantages and disadvantages of this method will be compared with quartz crystal microbalance techniques as well. It will also be shown that these two methods can be coupled for demanding applications. Results from the use of the MIDAS software in various applications will be presented.

Proceedings Article | 24 July 2002 Paper

Paper

Novel bilayer resist approach using radiation sensitive organometalics precursors

Augustin Jeyakumar, Sean Barstow, Clifford Henderson

Proceedings Volume 4690, (2002) https://doi.org/10.1117/12.474179

KEYWORDS: Etching, Electron beams, Metals, Oxides, Plasma, Photomasks, Reactive ion etching, Lithography, Electron beam lithography, Oxygen

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Proceedings Article | 24 July 2002 Paper

Paper

Polysulfone-novolac resist for electron-beam lithography: II. effects of resist formulation and processing

Ankur Agrawal, Clifford Henderson

Proceedings Volume 4690, (2002) https://doi.org/10.1117/12.474244

KEYWORDS: Electron beams, Microchannel plates, Diffractive optical elements, Polymers, Lithography, Solids, Electron beam lithography, Etching, Standards development, Mask making

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Proceedings Article | 24 July 2002 Paper

Paper

Synthesis and characterization of photodefinable polycarbonates for use as sacrificial materials in the fabrication of microfluidic devices

Celesta White, Clifford Henderson

Proceedings Volume 4690, (2002) https://doi.org/10.1117/12.474222

KEYWORDS: Polymers, Microfluidics, Glasses, Carbonates, Fabrication, Microelectromechanical systems, Complex systems, Silicon, Integration, Dielectrics

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A fabrication technique recently developed at Georgia Institute of Technology involving thermally sacrificial polymeric materials allows for fabrication of microfluidic devices with greater degrees of functionality (i.e., fully integrated, complex, multi-level fluidic systems with functional valves, pumping systems, and other micro- electromechanical system [MEMS] components). In this method, thermally sacrificial polymers are coated onto a substrate and patterned into the shape of the desired channels and devices. These polymeric structures are then over-coated with a permanent structural material such as an inorganic glass or polymer. These steps can be repeated to produce complex, three-dimensional systems. Once the device build-up is complete, the structure is heated to a temperature at which the sacrificial polymer slowly decomposes, thus leaving behind the desired open-channeled structures. This process was first developed using functionalized polynorbornenes that decompose at temperatures in the range of 425 degree(s)C. In order to make this approach compatible with a wider range of substrates and structural materials, polymers with lower decomposition temperatures were desired. Polycarbonates were identified as a class of polymers with the desired lower decomposition temperatures (200- 300 degree(s)C). A disadvantage of commercially available polycarbonates, like poly (propylene carbonate), is that they have low glass transition temperatures (T_gapproximately equals 40 degree(s)C). This introduces several problems, including pattern deformation at elevated processing temperatures. Also, a significant number of process steps are required to pattern the channel structures using simple polymer materials. Therefore, this paper will describe recent results of work on photodefinable polycarbonates with improved thermal properties. Utilizing a polymer that can be patterned directly by conventional lithography greatly simplifies the fabrication process and eliminates the need for the plasma etch steps required in the original process. Results of the synthesis and characterization of polycarbonates patterned with the use of a photoacid generator, thus exploiting the acid-catalyzed thermolysis of polycarbonates, will be presented.

Proceedings Article | 24 July 2002 Paper

Paper

Polysulfone-novolac resist for electron beam lithography: part I. fundamental studies of resist properties

Ankur Agrawal, Clifford Henderson

Proceedings Volume 4690, (2002) https://doi.org/10.1117/12.474191

KEYWORDS: FT-IR spectroscopy, Polymethylmethacrylate, Electron beams, Polymers, Absorbance, Ions, Crystals, Silicon films, Electron beam lithography, Quartz

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Proceedings Article | 24 July 2002 Paper

Paper

Novel surface imaging method using surface monolayer initiated polymerization

Kendra McCoy, Charles Gumieny, Dennis Hess, Laren Tolbert, Clifford Henderson

Proceedings Volume 4690, (2002) https://doi.org/10.1117/12.474178

KEYWORDS: Silicon, Chlorine, Polymerization, Polymers, X-rays, Deep ultraviolet, Ultraviolet radiation, Etching, Image processing, Lithography

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Proceedings Article | 1 July 2002 Paper

Paper

Direct photopatterning of metal oxide materials using photosensitive organometallic precursor films

Sean Barstow, Augustin Jeyakumar, Clifford Henderson

Proceedings Volume 4688, (2002) https://doi.org/10.1117/12.472317

KEYWORDS: Oxides, Dielectrics, Metals, Capacitors, Carbon, Ultraviolet radiation, Lithography, Barium, Strontium, Etching

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Proceedings Article | 11 June 1999 Paper

Paper

Optical lithography simulation and photoresist optimization for photomask fabrication

Benjamen Rathsack, Cyrus Tabery, Steven Scheer, Mike Pochkowski, Cecilia Philbin, Franklin Kalk, Clifford Henderson, Peter Buck, C. Grant Willson

Proceedings Volume 3678, (1999) https://doi.org/10.1117/12.350173

KEYWORDS: Photomasks, Refraction, Lithography, Picture Archiving and Communication System, Data modeling, Photoresist materials, Device simulation, Chromium, Photoresist processing, Optical simulations

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Proceedings Article | 29 June 1998 Paper

Paper

Some aspects of thick-film resist performance and modeling

Andreas Erdmann, Clifford Henderson, C. Grant Willson, Ralph Dammel

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312349

KEYWORDS: Refractive index, Computer simulations, Photoresist processing, Photoresist materials, Optical simulations, Performance modeling, Data modeling, Scanning electron microscopy, Diffraction, Photoresist developing

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Proceedings Article | 29 June 1998 Paper

Paper

Modeling parameter extraction for DNQ-novolak thick film resists

Clifford Henderson, Steven Scheer, Pavlos Tsiartas, Benjamen Rathsack, John Sagan, Ralph Dammel, Andreas Erdmann, C. Grant Willson

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312415

KEYWORDS: Refractive index, Data modeling, Photoresist developing, Photoresist materials, Reflectivity, Software development, Silicon, Lithography, Absorbance, Picture Archiving and Communication System

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Proceedings Article | 29 June 1998 Paper

Paper

Improved simulation of photoresists using new development models

Ralph Dammel, John Sagan, Elaine Kokinda, Neville Eilbeck, Chris Mack, Graham Arthur, Clifford Henderson, Steven Scheer, Benjamen Rathsack, C. Grant Willson

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312399

KEYWORDS: Photoresist developing, Data modeling, Photoresist materials, Radon, Autoregressive models, Diffusion, Affine motion model, Standards development, Chlorine, Picture Archiving and Communication System

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Proceedings Article | 29 June 1998 Paper

Paper

Dissolution of phenolic polymers in aqueous base: the influence of polymer structure

Christopher McAdams, Lewis Flanagin, Clifford Henderson, Adam Pawlowski, Pavlos Tsiartas, C. Grant Willson

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312345

KEYWORDS: Polymers, Ionization, Hydrogen, Photoresist materials, Diffusion, Deep ultraviolet, Chromophores, Photoresist developing, Polarization, Ions

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Proceedings Article | 29 June 1998 Paper

Paper

Top surface imaging through silylation

Sergei Postnikov, Mark Somervell, Clifford Henderson, Steven Katz, C. Grant Willson, Jeff Byers, Anwei Qin, Qinghuang Lin

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312370

KEYWORDS: Etching, Lithography, Diffusion, Photoresist materials, Image processing, Semiconducting wafers, Photoresist processing, Oxygen, Absorbance, Silicon

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Proceedings Article | 29 June 1998 Paper

Paper

Probabilistic model for the mechanism of phenolic polymer dissolution

Lewis Flanagin, Christopher McAdams, Pavlos Tsiartas, Clifford Henderson, William Hinsberg, C. Grant Willson

Proceedings Volume 3333, (1998) https://doi.org/10.1117/12.312416

KEYWORDS: Polymers, Polymerization, Ionization, Photoresist materials, Data modeling, Diffusion, Polymer thin films, Photoresist developing, Etching, Polymethylmethacrylate

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Proceedings Article | 8 June 1998 Paper

Paper

Refractive-index measurements of photoresist and antireflective coatings with variable angle spectroscopic ellipsometry

Ron Synowicki, James Hilfiker, Ralph Dammel, Clifford Henderson

Proceedings Volume 3332, (1998) https://doi.org/10.1117/12.308747

KEYWORDS: Refractive index, Antireflective coatings, Data modeling, Photoresist materials, Spectroscopic ellipsometry, Data acquisition, Polarization, Ultraviolet radiation, Lithography, Monochromators

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Proceedings Article | 7 July 1997 Paper

Paper

Diffusivity measurements in polymers: II. Residual casting solvent measurement by liquid scintillation counting

Allen Gardiner, Anwei Qin, Clifford Henderson, Sanju Pancholi, William Koros, C. Grant Willson, Ralph Dammel, Chris Mack, William Hinsberg

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275886

KEYWORDS: Scintillation, Diffusion, Liquids, Process control, Refraction, Data modeling, Semiconducting wafers, Picture Archiving and Communication System, Temperature metrology, Polymers

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Proceedings Article | 7 July 1997 Paper

Paper

Photoresist characterization for lithography simulation: II. Exposure parameter measurements

Clifford Henderson, Sanju Pancholi, Sajed Chowdhury, C. Grant Willson, Ralph Dammel

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275883

KEYWORDS: Refractive index, Photoresist materials, Transmittance, Reflection, Absorption, Lithography, Picture Archiving and Communication System, Quartz, Photoresist processing, Data modeling

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Proceedings Article | 7 July 1997 Paper

Paper

Bleaching-induced changes in the dispersion curves of DNQ photoresists

Clifford Henderson, C. Grant Willson, Ralph Dammel, Ron Synowicki

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275861

KEYWORDS: Refractive index, Photoresist materials, Lithography, Absorption, Absorbance, Ultraviolet radiation, Data modeling, Semiconducting wafers, Dielectrics, Spectroscopic ellipsometry

Read Abstract +

Proceedings Article | 7 July 1997 Paper

Paper

Influence of optical nonlinearities of the photoresist on the photolithographic process: applications

Andreas Erdmann, Clifford Henderson, C. Grant Willson, Wolfgang Henke

Proceedings Volume 3048, (1997) https://doi.org/10.1117/12.275810

KEYWORDS: Refractive index, Photoresist materials, Nonlinear optics, Absorption, Standards development, Photoresist processing, Phase shifts, Lithography, Imaging systems, Diffusion

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Proceedings Article | 7 July 1997 Paper

Paper

Photoresist characterization for lithography simulation: IV. Processing effects on resist parameters

Clifford Henderson, Pavlos Tsiartas, Lewis Flanagin, Sanju Pancholi, Sajed Chowdhury, Katherine Dombrowski, Ammar Chinwalla, C. Grant Willson

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275820

KEYWORDS: Photoresist developing, Semiconducting wafers, Photoresist materials, Lithography, Picture Archiving and Communication System, Refractive index, Absorption, Photoresist processing, Statistical analysis, Data modeling

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Proceedings Article | 7 July 1997 Paper

Paper

Photoresist characterization for lithography simulation: III. Development parameter measurements

Clifford Henderson, Pavlos Tsiartas, Sanju Pancholi, Sajed Chowdhury, Katherine Dombrowski, C. Grant Willson, Ralph Dammel

Proceedings Volume 3049, (1997) https://doi.org/10.1117/12.275882

KEYWORDS: Photoresist developing, Data modeling, Picture Archiving and Communication System, Diffusion, Refractive index, Photoresist materials, Lithography, Information operations, Semiconducting wafers, Silicon

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Proceedings Article | 7 July 1997 Paper

Paper

Influence of optical nonlinearities of the photoresist on the photolithographic process: basics

Andreas Erdmann, Clifford Henderson, C. Grant Willson, Wolfgang Henke

Proceedings Volume 3051, (1997) https://doi.org/10.1117/12.276032

KEYWORDS: Photoresist materials, Refractive index, Nonlinear optics, Beam propagation method, Lithography

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Proceedings Article | 14 June 1996 Paper

Paper

Factors affecting the dissolution rate of novolac resins II: developer composition effects

Clifford Henderson, Pavlos Tsiartas, Logan Simpson, Kelly Clayton, Sanju Pancholi, Adam Pawlowski, C. Grant Willson

Proceedings Volume 2724, (1996) https://doi.org/10.1117/12.241846

KEYWORDS: Ions, Polymers, Alkali metals, Potassium, Macromolecules, Interfaces, Polymer thin films, Molecules, Photoresist developing, Photoresist materials

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Showing 5 of 119 publications

Proceedings Volume Editor (4)

SPIE Conference Volume | 30 March 2009

Advances in Resist Materials and Processing Technology XXVI

SPIE Conference Volume | 24 April 2008

Advances in Resist Materials and Processing Technology XXV

SPIE Conference Volume | 15 March 2007

Advances in Resist Materials and Processing Technology XXIV

SPIE Conference Volume | 9 March 2006

Advances in Resist Technology and Processing XXIII

Conference Committee Involvement (23)

Advances in Patterning Materials and Processes XLII

23 February 2025 | San Jose, California, United States

Advances in Patterning Materials and Processes XLI

26 February 2024 | San Jose, California, United States

Advances in Patterning Materials and Processes XL

27 February 2023 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXIX

25 April 2022 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXVIII

22 February 2021 | Online Only, California, United States

Advances in Patterning Materials and Processes XXXVII

24 February 2020 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXVI

25 February 2019 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXV

27 February 2018 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXIV

28 February 2017 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXIII

29 February 2016 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXII

24 February 2015 | San Jose, California, United States

Advances in Patterning Materials and Processes XXXI

24 February 2014 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXX

25 February 2013 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXIX

13 February 2012 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXVIII

28 February 2011 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXVII

22 February 2010 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXVI

23 February 2009 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXV

25 February 2008 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXIV

26 February 2007 | San Jose, California, United States

Advances in Resist Materials and Processing Technology XXIII

20 February 2006 | San Jose, California, United States

Advances in Resist Technology and Processing XXII

28 February 2005 | San Jose, California, United States

Advances in Resist Technology and Processing XXI

23 February 2004 | Santa Clara, California, United States

Advances in Resist Technology and Processing XX

24 February 2003 | Santa Clara, California, United States

Showing 5 of 23 Conference Committees

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