A novel method to reduce wafer topography effect for implant lithography process

Abstract

Wafer topography structures in the implant lithography process, which include the shallow trench isolation and the poly gate, can result into a severe degradation of the resist profile and significant critical dimension variation. While bottom anti-reflective coating (BARC) is not suitable for the implant lithography because of the plasma induced substrate damage, developable bottom anti-reflective coating (DBARC) is now the most promising solution to eliminate wafer topography effects for the implant layer lithography. Currently, some challenges still remain to be solved and DBARC is not ready for mass production yet. In this study, a novel method is proposed to improve wafer topography effects by use of sub-resolution features. Compared with DBARC, this new approach is much more cost effective. Numerical study by use of Sentaurus-Litho simulation tool shows that the new method is promising and deserves more comprehensive investigation.

Simple method for decreasing wafer topography effect for implant mask

“…The simple method is utilizing sub-resolution features that will imitigatethe incoming light attributed to the destructive topography reflection. Previous SPIE papers have been using the SRLB(sub-resolution light blockade) term to segregate itself from SRAF [5]. Normaly SRAF is using to enhance the process window of isolated and semi dense features by enhansing optical interference between the main patterns and assist patterns.…”