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17 May 1994 Comparison of phase-shift mask types for submicrometer contact hole definition
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Rim and attenuated phase shift masks (PSMs) are the most promising candidates for mass ASIC production. Computer simulations have been carried out to compare their merits and limitations. It has been shown that both rim and attenuated PSMs improve the exposure latitude and depth of focus compared with a conventional binary intensity mask. An attenuated PSM demonstrates a higher exposure level and better defocus performance than a rim PSM, especially for sub-half micron contact holes. The comparison is based on a combination of criteria, since it is found that different conclusions may arise from computer simulations based on the analysis of an aerial image, if different evaluation criteria, such as log-intensity slope, image contrast or exposure-defocus tree, are applied independently. Examples illustrate the importance of choice of evaluation criteria. The superior performance of the attenuated PSM over conventional masks is confirmed by i-line experimental lithography.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zheng Cui, Brian Martin, Philip D. Prewett, Steve Johnson, and Philip Herman "Comparison of phase-shift mask types for submicrometer contact hole definition", Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994);

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