Patent ID: 6461887
Filing Date: 2002-10-08
Classification: H01L

Abstract:
A method of forming an inverted staircase shaped STI structure, comprising the steps of:a) providing a semiconductor substrate having an overlying oxide layer; said substrate having at least a pair of active areas defining an STI region therebetween; b) etching said oxide layer a first time within said active areas to form first step trenches; said first step trenches having exposed sidewalls; c) forming continuous side wall spacers on said exposed first step trench sidewalls; d) etching said oxide layer 1 or more successive times using the previously formed step side wall spacers as masks to form successive step trenches within said active areas; each said successive step trenches having exposed sidewalls and having side wall spacers successively formed on said successive step trench exposed sidewalls; e) etching said oxide layer a final time using the previously formed step side wall spacers as masks to form final step trenches exposing said substrate within said active areas; said STI region comprising an inverted staircase shaped STI structure; f) removing all of said step side wall spacers from said step trenches; and g) forming planarized active area silicon structures within said final step trenches and forming semiconductor deveices thereon.