Control of semiconductor manufacturing: CMP & thickness variations

Abstract

Chemical mechanical polishing (CMP) has be-come, in a few short years, an indispensable semiconductor processing module used in fabrication facilities worldwide.The lack of in-situ measurements of the product qualitiesof interest, in this case, the surface thickness uniformity,makes Run to run (R2R) control the only viable scheme in most semiconductor manufacturing processes. The literature contains many variations of R2R control schemes to control the CMP process. In this paper, we analyze the performance of these R2R control schemes and proposed aself-tuning predictor-corrector controller (PCC). Initial simulation results depicts order of magnitude improvement in the within wafer uniformity as compared to traditional R2Rcontrol schemes.