STI HARP gap-fill thickness uniformity improvement for 14nm nodes

Abstract

High aspect ratio process (HARP) is a non­plasma based CVD oxide film that addresses the gap fill requirements for shallow trench isolation (STI) at the 4xnm node and beyond. As IC technology advances to 14nm FINFET processor, besides good gap fill performance to high aspect ratio profile, capping layer thickness uniformity to help reduce downstream chemical mechanical polishing (CMP) micro scratch has become a significant process challenge. In this work, we adapt center hole faceplate to bring up wafer center point thickness during HARP gap fill process, to improve thickness uniformity for post CMP donut region micro scratch reduction. The results show that with center hole face plate, HARP gap fill film has good thickness uniformity, with thickness range from wafer center to edge reduced. Bright field scan and SEM review on downstream wafer after CMP process show that donut region micro scratch defects are reduced.