A method of assist feature OPC layout is introduced using a frequency model-based approach. Through low-pass spatial frequency filtering of a mask function, the local influence of zero diffraction energy can be determined. By determining isofocal intensity threshold requirements of an imaging process, a mask equalizing function can be designed. This provides the basis for frequency model-based assist feature layout. By choosing assist bar parameters that meet the requirements of the equalizing function, through-pitch focus and dose matching is possible for large two dimensional mask fields. The concepts introduced also lead to additional assist feature options and design flexibility .
Date of creation, presentation, or exhibit
Department, Program, or Center
Microelectronic Engineering (KGCOE)
Bruce W. Smith, Dale E. Ewbank, "OPC and image optimization using localized frequency analysis", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474509; https://doi.org/10.1117/12.474509
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