Latitude of the BAR process compared to the monolayer and TAR processes for 0.35-μm design rules at gate level

Abstract

The aim of this paper is to investigate experimentally the performances of three photolithographic processes, the monolayer, AQUATAR® and BARLi® processes, for 0.35 jim patterning using the Exposure-Defocus (E-D) Tree technique ('). Parameters of practical importance are considered such as exposure latitude and depth of focus for dense and isolated features, and their overlapping latitudes, i.e. the proximity effect.The influence of the resist thickness (minimum and maximum incoupling thicknesses) and the impact of a 50 rtn sizing of the mask have also been evaluated.Using the BARLi® process, significant improvements have been demonstrated for proximity and CD swing effects. The results highlight the problems of pushing i-line lithography to the 0.35 jim regime and demonstrate that, to achieve acceptable CD control, a BAR process must be used.