公开(公告)号：US20080293213A1

公开(公告)日：2008-11-27

申请号：US11774811

申请日：2007-07-09

Applicant: Neng Hui Yang ,  Hai Jun Zhao

Inventor： Neng Hui Yang ,  Hai Jun Zhao

IPC: H01L21/76

CPC classification number: H01L21/76237 ,  H01L21/76235

Abstract: A method for preparing a shallow trench isolation comprising the steps of forming at least one trench in a semiconductor substrate, performing an implanting process to implant nitrogen-containing dopants into an upper sidewall of the trench such that the concentration of the nitrogen-containing dopants in the upper sidewall is higher than that in the bottom sidewall of the trench, forming a spin-on dielectric layer filling the trench and covering the surface of the semiconductor substrate, performing a thermal oxidation process to form a silicon oxide layer covering the inner sidewall. Since the nitrogen-containing dopants can inhibit the oxidation rate and the concentration of the nitrogen-containing dopants in the upper inner sidewall is higher than that in the bottom inner sidewall of the trench, the thickness of the silicon oxide layer formed by the thermal oxidation process is larger at the bottom portion than at the upper portion of the trench.