公开(公告)号：US20210287932A1

公开(公告)日：2021-09-16

申请号：US16483081

申请日：2018-07-03

Applicant: CSMC Technologies FAB2 Co., Ltd.

Inventor： Shukun Ql

IPC: H01L21/762 ,  H01L29/06 ,  H01L21/02 ,  H01L21/311 ,  H01L21/32 ,  H01L21/265 ,  H01L21/3105 ,  H01L21/761

Abstract: A method for manufacturing a trench isolation structure comprising forming a shallow trench having a wider upper section and a narrower lower section in a wafer surface, removing part of the silicon oxide by etching, forming a silicon oxide corner structure at a corner at a top corner of the shallow trench by thermal oxidation, depositing silicon nitride on the wafer surface to cover surfaces of the shallow trench silicon oxide and the silicon oxide corner structure, dry etching the silicon nitride on the shallow trench silicon oxide surface thereby forming masking silicon nitride residues extending into the trench, etching downwards to form a deep trench, forming silicon oxide layers on a side wall and the bottom of the deep trench, depositing polycrystalline silicon in the shallow and deep trenches, removing the silicon nitride, and forming silicon oxide in the shallow trench to cover the polycrystalline silicon.