FAST PROXIMITY EFFECT CORRECTION - AN EXTENSION OF PYRAMID FOR CIRCUIT PATTERNS OF ARBITRARY SIZE

Previously, we introduced PYRAMID, a hierarchical pattern shape modification scheme for proximity effect correction in electron-beam lithography, which enabled rapid correction of circuit patterns with linewidths down to 0.1 mum. However, it was limited to relatively small circuit patterns only. This article describes an extension of PYRAMID for circuit patterns of arbitrary size, as well as additional improvements to the previous implementation. PYRAMID is a fast hierarchical pattern modification scheme that can be conceptually partitioned into two phases: local correction to account for circuit components separated by small distances (approximately 1 mum) and global correction for circuit components separated by larger distances. PYRAMID supports input circuits composed of arbitrarily partitioned rectangles, as well as 135-degrees angle path inputs. Also, a segmented mode of operation allows a large circuit to be corrected one segment at a time, thereby reducing computer memory requirements. Experimental results showing the successful correction of a relatively large test pattern (with linewidths as small as 0.1 mum) in 200 nm PMMA resist are provided along with correction times as a function of the number of circuit components.