INVESTIGATION OF MASK PATTERN PROXIMITY CORRECTION TO REDUCE IMAGE SHORTENING IN X-RAY-LITHOGRAPHY

Previous experimental studies of proximity x-ray lithography for compl ex patterning at 75-125 nm linewidths have indicated that image shorte ning is significant at >10 mu m gaps [1,2]. Simple serifs added to lin e ends have been shown to reduce line-end shortening for 75-125 nm gro und-rule SRAM-like (static random access memories) patterns. However, line-end shortening is still >30 nm for 85 nm ground-rule patterns at 10-15 mu m gaps. In this study, simulations are used to evaluate requi rements on serif patterning to reduce line-end shortening. Initial exp erimental results using positive resist indicate that negative tone ma sk patterns may result in less line-end shortening.