Resolution Improvement Using Auxiliary Pattern Groups in Oblique Illumination Lithography

In this paper we present a new resolution improvement technique for nonperiodic patterns where oblique illumination effects are limited. Since the problems are caused by nonperiodicity, a technique called auxiliary pattern group (APG) is introduced to supplement the periodicity. The effects of the APG are shown by simulation, and parameter dependence is also discussed. Experimental results for oblique illumination with a t-pi mask confirm that using APGs improves the resolution and focus latitude.