Metal CMP process optimization for low abrasive slurry

Abstract

CMP underpolish defects at back-end-of the line copper-CMP processes presents critical device reliability issues and can drive lower yields. Lower scratch defects and metal-metal isolation are the key requirements for a stable device performance. New generation low solid content slurries provide lower defects and good dishing attributes, however present planarization challenges to varying device densities. This article highlights the process optimizations that enabled the implementation of a new generation slurry on n-1 technology nodes and presents hypothesis for material removal mechanisms involving metal CMP processes. It also proposes the need to implement new material qualification BKM's across device densities and reticle design rules to enable a stable CMP planarization process.