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Proceedings Paper

A Comparison Of The Optical Projection Lithography Simulators In Sample And Prolith
Author(s): O. D. Crisalle; S. R. Keifling; D. E. Seborg; D. A. Mellichamp
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Paper Abstract

SAMPLE and PROLITH are two computer programs widely available for simulating the optical projection photolithography process. Both programs use a combination of physical and empirical models to determine the profile in a developed resist given various imaging, exposure, and development data. Although both programs perform basically the same functions, they rely on different models and numerical algorithms for the calculation of aerial and latent images, and differ in the method adopted for propagating the development front. A notable difference to the user is that the programs also use different development-rate models. This paper documents algorithmic details not available in the open literature on these programs, and presents simulation results of representative lithography systems to illustrate differences and similarities in the developed photoresist profiles and in relevant intermediate steps. Numerical comparison demonstrates that aerial images calculated by SAMPLE and PROLITH are in generally good agreement. It is found that resist cross-sectional profiles produced by the programs at high numerical resolution provide the same qualitative lithography information for representative systems; however, a significant disagreement is found in the output of the post-exposure bake algorithms since SAMPLE predicts much lower standing-wave amplitude attenuation effects. It is argued that the dissimilar development-rate models used by each simulator do not contribute significantly to differences observed in the cross-sectional profile output. A noteworthy difference is that PROLITH is capable of predicting the asymmetric behavior observed in experimental data relating critical dimensions to defocus, whereas SAMPLE predicts completely symmetric behavior. The band algorithm used in SAMPLE for the calculation of linewidths is found to be an adequate method for estimating critical dimensions.

Paper Details

Date Published: 30 January 1990
PDF: 17 pages
Proc. SPIE 1185, Dry Processing for Submicrometer Lithography, (30 January 1990); doi: 10.1117/12.978058
Show Author Affiliations
O. D. Crisalle, University of California (United States)
S. R. Keifling, University of California (United States)
D. E. Seborg, University of California (United States)
D. A. Mellichamp, University of California (United States)

Published in SPIE Proceedings Vol. 1185:
Dry Processing for Submicrometer Lithography
James A. Bondur; Alan R. Reinberg, Editor(s)

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