Microfabrication

Impact of polymer curing on two-dimensional and three-dimensional shape change in nanoimprint lithography

[+] Author Affiliations
Meghali J. Chopra, Roger T. Bonnecaze

University of Texas at Austin, Chemical Engineering, 200 East Dean Keeton, Austin, Texas 78712, United States

J. Micro/Nanolith. MEMS MOEMS. 14(4), 044502 (Oct 21, 2015). doi:10.1117/1.JMM.14.4.044502
History: Received August 11, 2015; Accepted September 25, 2015
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Abstract.  Polymer shrinkage from curing in nanoimprint lithography (NIL) strongly affects the ultimate shapes of two- and three-dimensional structures produced following etching. We computationally study the curing step in the NIL process and predict the shape changes caused by polymer shrinkage. The shape changes are predicted for crosses, diamonds with sharp and rounded tips, and multitiered structures that are applicable for multibit memory devices and dual damascene processes. The shape changes from curing are shown to be governed by the shrinkage coefficient of the polymer resist, its Poisson’s ratio, and the geometric aspect ratios of the shapes. Finite element simulations demonstrate that shape change due to polymer densification is equal to the average volumetric contraction of the resist material, but shrinkage is not isotropic and vertical displacement dominates. The thickness of the residual layer does not impact the final profile of the imprinted shapes considered. Further analysis shows that diamonds with sharp tips stay sharp while the tips of rounded diamonds get sharper. Additionally, shape changes for multitiered structures are not uniformly distributed among the tiers. Using etch simulations, we demonstrate the significant impact of polymer shrinkage on the final feature profile.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Meghali J. Chopra and Roger T. Bonnecaze
"Impact of polymer curing on two-dimensional and three-dimensional shape change in nanoimprint lithography", J. Micro/Nanolith. MEMS MOEMS. 14(4), 044502 (Oct 21, 2015). ; http://dx.doi.org/10.1117/1.JMM.14.4.044502


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