Patent ID: 6274457
Filing Date: 2001-08-14
Classification: H01L

Abstract:
A method for manufacturing a semiconductor device, comprising:patterning an etching mask having a window on a surface of a semiconductor substrate;forming a sidewall deposit on a sidewall of said window;subjecting said substrate to first etching with use of said etching mask and said sidewall deposit to form a first trench in said substrate;eliminating said sidewall deposit;subjecting said substrate to second etching with use of said etching mask to dig said first trench and form a second trench so as to occupy a region corresponding to said window in said substrate;depositing a silicon oxide film on an inner wall of said second trench by thermal oxidation;depositing a buried oxide film on said silicon oxide film to bury said second trench; andeliminating said etching mask;wherein said second trench is formed so as to have portions of a sidewall sloped at a first profile angle A1 a second profile angle A2 and a third profile angle A3 from said surface of said substrate toward a bottom surface of said second trench, and said profile angles have a relationship of A1<A2, A3<A2 and A1<83.degree..