Patent ID: 6627512
Filing Date: 2003-09-30
Classification: H01L

Abstract:
A method of manufacturing a semiconductor device comprising steps of:(a) preparing an SOI substrate comprising a silicon substrate, a buried oxide film arranged on said silicon substrate and an SOI layer arranged on said buried oxide film; (b) forming an oxide extension layer on said SOI layer; (c) forming a mask layer having a prescribed opening pattern on said oxide extension layer; (d) forming a trench by selectively removing said SOI layer through said mask layer without passing through said SOI layer from the surface; (e) forming a resist mask having an opening at a first region between a prescribed position at least on the bottom surface of said trench and a first side wall surface in a brachydirectional section, and covering a second region between at least said prescribed position and a second side wall surface in said brachydirectional section; (f) removing said trench to reach said buried oxide film through said resist mask for forming a combined trench having a portion corresponding to said second region being a partial trench having said SOI layer on its lower portion and a portion corresponding to said first region being a full trench passing through said SOI layer; (g) forming a first oxide film on the inner wall of said combined trench by thermally oxidizing the inner wall of said combined trench and said oxide extension layer; and (h) forming a trench isolation oxide film combinationally having a full trench structure reaching said buried oxide film through said SOI layer and a partial trench structure having said SOI layer on its lower portion by filling up said combined trench with a second oxide film.