Patent ID: 9147739
Filing Date: 2015-09-29
Classification: H01L

Abstract:
1. A method for forming polysilicon in a trench, comprising: providing a substrate; forming a first dielectric layer on said substrate; forming an opening in said first dielectric layer by etching; forming a trench in said substrate by etching through said opening; forming a second dielectric layer on sidewalls of said trench; forming polysilicon on a surface of said substrate and on a surface of said second dielectric layer in said trench; applying a sacrificial layer made of photoresist or spin-on glass on a surface of polysilicon to provide a flat surface; and removing said sacrificial layer and a portion of polysilicon on said surface of said substrate successively by etching, while a portion of polysilicon remaining in said trench is etched to a predetermined depth below said surface of said substrate.