We describe progress in low-k1 factor double patterning using 172 nm ultraviolet (UV) curing as a resist stabilization
method. Factors that have contributed to enhanced patterning capability include a) resists design and optimization for
both patterning and UV curing; b) use of unique R&D tooling capabilities to rapidly identify and optimize key process
variables; c) development of simple process metrics for characterizing double patterning process quality, and d) use of
172 nm-resistant antireflective materials. A designed resist, XP-7600A, was selected for detailed evaluation based on
superior patterning and curing behavior (less than 10 percent volumetric shrinkage during cure.) Process optimization
on 172 nm damage-prone antireflective coatings produced 60 nm cross-grid contact holes at 0.93 NA (litho k1 = 0.28)
with good uniformity when an ancillary 150 °C post-UV bake was used. Additional optimization on improved
antireflective coatings yielded superior process latitude (>20 percent 172 nm dose latitude) and also demonstrated that a
UV-cure-only resist stabilization process flow may be attainable. Under optimized conditions, highly uniform 60 nm
half-pitch cross-grid contacts with cross-sectional area uniformity (1σ) of approximately 200 nm2 (5 percent) are
produced at 135 nm resist film thickness.
This study reports on blob defect reduction and process impacts by Acid Rinse System. Blob defects that appear after
develop are a common problem with i-line, KrF, ArF and ArF-immersion resists. Last year we reported Blob defects
were influenced by the develop process and were able to be decreased by improving process. Furthermore we identified
blob defects were caused from alkaline developer and could be reduced by neutralizing Acid Rinse.
In this work, we designed a novel develop process and system that reduced blob defects. We evaluated this system on
the non-topcoat immersion resist. The blob defects on immersion resist were also eliminated by this system but affected
by each resist surface condition. We also evaluated the impacts from Acid rinse for some kinds of patterns and resists,
because we needed to indentify whether there were negatively process impacts.
We reports that Acid Rinse System significantly reduced blob defect counts, and whether influenced other process
impacts. Finally we report the mechanism of the blob defects reduction.
As IC manufactures explore different paths to meet the resolution requirements for next generation technology,
patterning schemes which utilize a double photoresist patterning process are under extensive evaluation. One dual
patterning process under consideration uses a 172nm UV cure to render the first photoresist pattern insoluble to the
casting solvents and developer chemistries used to define the second photoresist pattern. In this work we investigate the
change in the material properties such as thickness, optical, bond structure, adhesion and stability of the SiBARC film
due to the UV cure. Simulations are included to assess the change in substrate reflectance due to the change in the optical
properties of the SiBARC film as a result of the UV cure. Single patterned photoresist line space features versus UV cure
dose of the SiBARC - under layer film stack is presented. This is followed by cross-grid and pitch-split double patterning using 172 nm UV light of varying dose to freeze the first photoresist layer patterned using a tri-layer film configuration.
There is a limit to the minimum feature size that can be printed using current lithographic techniques. For that reason,
engineers often employ various shrink methods in production to reduce the size of features generated by lithography.
One such technique is the application of a shrink assisted film for enhanced resolution (SAFIER). In such a process, a
SAFIER chemical is coated onto a patterned photoresist and baked. During the bake, the resist expands, and hence, the
patterned spaces in the resist shrink. The shrink process, however, does not necessarily occur uniformly across the
wafer, and some critical dimension (CD) non-uniformity can be introduced during this step. This study investigates the
efficacy of using an intentionally biased SAFIER bake temperature profile to compensate for some of the CD nonuniformities
introduced during the SAFIER process. In the baseline case, patterned wafers underwent a standard
SAFIER process using a thermally uniform bake. The bake temperature of the SAFIER bake was then biased to cancel
out some of the shrink induced CD non-uniformity. Wafers processed through the biased temperature SAFIER bake
showed a 20% improvement in post-SAFIER (critical dimension uniformity) CDU. For comparison, a biased post
exposure bake (PEB) temperature was used to create wafers with a non-uniform starting CD distribution designed to
cancel out some of the CD non-uniformity from the SAFIER process. When these wafers were processed through a
uniform temperature SAFIER process, a 54% improvement in post SAFIER CDU was observed over the baseline case.
Increasing levels of metallization, shrinking device geometries, and stringent defect density requirements have led to a continuous focus in the semiconductor manufacturing community to reduce defects generated during metal deposition by PVD techniques. Pareto analysis of in-film defects in currently used interconnect metallization schemes suggest that a considerable portion of the in-film defects (up to 50%) are caused by Unipolar arcing during Aluminum deposition. Due to their unusual molten appearance, these defects are commonly referred to as `Splats'. These defects can be as large as 500 micrometers , and because of their metallic nature have a high probability of causing device failure. Due to their frequency of occurrence and size, these Splats can significantly impact device yield in a manufacturing environment. Systematic investigations have been carried out for the identification and characterization of these in-film defects, using a combination of Tencor Surfscan, Optical and Ultrapointe Microscopy and SEM FIB analysis. This analysis has revealed these Splats result from localized melting or explosions on the target surface, due to Unipolar arcing. This Unipolar arcing can be strongly correlated to presence of undesirable metallurgical attributes such as Alumina inclusions, porosity, oxygen content etc. in the target. The results of this study indicate that by the reduction/elimination of these various undesirable metallurgical attributes in the Aluminum alloy targets a significant improvement in defect generation during sputter deposition of Aluminum films, and hence an improvement in device yield, is possible.
Increasing levels of metallization, shrinking device geometries, and stringent defect density requirements have led to a continuous focus in the semiconductor manufacturing community to reduce defects generated during metal deposition by PVD techniques. Of particular interest in the metallization community is the reduction in in-film defect density in sputtered aluminum films. Pareto analysis of in-film defects in currently used interconnect metallization schemes suggest that a considerable portion of the in-film defects (up to 50%) are caused by unipolar arcing during aluminum deposition. Due to their unusual molten appearance, these defects are commonly referred to as splats. These defects can be as large as 500 micrometers , and due to their frequency of occurrence and size can significantly impact device yield in a manufacturing environment. Systematic investigations have revealed that the formation of splats, due to unipolar arcing, can be strongly correlated to the metallurgy of the aluminum alloy targets used during aluminum sputter deposition. The presence of undesirable metallurgical attributes such as alumina inclusions, porosity, oxygen content etc. are the primary causes for the occurrence of unipolar arcing. These undesirable metallurgical attributes appear to be the result of the manufacturing processes used to manufacture the aluminum alloy targets. The results of this study indicate that significant improvement in defect generation due to unipolar arcing during sputter deposition of aluminum films, and hence an improvement in device yield, is possible by reduction/elimination of the various undesirable metallurgical attributes in the aluminum alloy targets.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.