Method for manufacturing an isolation trench having plural profile angles
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsMaiko Sakai, Takashi Kuroi, Katsuyuki Horita
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Abstract
A semiconductor device comprising a semiconductor substrate, a trench formed in the substrate and having an inner wall including a sidewall and a bottom surface, a silicon oxide film deposited on the inner wall, and a buried oxide film deposited on the silicon oxide film to bury the trench, wherein the sidewall has portions of a sidewall sloped at a first profile angle A1, a second profile angle A2 and a third profile angle A3 from a surface of the substrate toward the bottom surface of the trench, and the profile angles have a relationship of A1<A2, A3<A2 and A1<83°.
Claims4
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;
- and
- eliminating 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°.
A method for manufacturing a semiconductor device, comprising:
- patterning an etching mask having a window on a surface of a semiconductor substrate;
- forming a first sidewall deposit on a sidewall of said window;
- subjecting said substrate to first etching with use of said etching mask and said first sidewall deposit to form a first trench in said substrate;
- reducing a size of said first sidewall deposit in a horizontal direction to form a second sidewall deposit;
- subjecting said substrate to second etching with use of said second sidewall deposit and said etching mask to dig said first trench and form a second trench;
- eliminating said second sidewall deposit;
- 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;
- and
- eliminating 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°.
Dependencies are inferred from the claim text.