Monitoring of subquartermicron line and space pattern by ellipsometry

This article reports on the ellipsometric monitoring of 0.3- and 5-mu m pitch line/space patterns fabricated by electron-beam (EB) lithography (HL700F). The effects of exposure dosage on pattern formations and the subsequent ellipsometric measurements were investigated. The results suggest that ellipsometry can be practical for monitoring pattern widths and cross-sectional shapes. Regression analysis was applied to predict the linewidths by using ellipsometric parameters. A good agreement between the predicted and actual values was achieved. Remaining errors of 3.7 and 2.8 nm are considered to be due to actual fluctuations in pattern widths or errors in CD-SEM measurements. Exposure doses which would provide a good index to ensure that patterns are well formed, and that the remaining resist is thick enough were also predicted. Regression analysis results were used to evaluate the widths of monitoring patterns fabricated regularly by a variable shaped EB machine (HL600) over the course of six months. (C) 1997 American Vacuum Society.