Method of fabricating semiconductor device

Claim 1

A method of fabricating a semiconductor device comprising: a. a step of forming an opening in a semiconductor substrate using a first antietching film formed on said semiconductor substrate and a first antioxidation film as masks; b. a step of forming a second antioxidation film on a whole surface of said semiconductor substrate by a reduced pressure CVD method and anisotropically etching the the second antioxidation film to expose the first antietching film on a top surface and the semiconductor substrate at a bottom surface of the opening; c. a step of forming a second antietching film on a whole surface of the semiconductor substrate by a reduced pressure CVD method and anisotropically etching the second antietching film to expose the first antietching film on a top surface and the semiconductor substrate at a bottom surface of the opening, said second antietching film being left only on a sidewall of the opening and covering said second antioxidation film; d. a step of performing isotropic dry etching using said first and second antietching films as masks; and e. a step of performing a heat treatment in an oxidizing atmosphere using said first and second antioxidation films as masks.

Claim 2

A method of fabricating a semiconductor device comprising: a. a step of forming an opening in a semiconductor substrate using a first antietching film formed on said semiconductor substrate and a first antioxidation film as masks; b. a step of forming a second antioxidation film on a whole surface of said semiconductor substrate by a reduced pressure CVD method and anisotropically etching the the second antioxidation film to expose the first antietching film on a top surface and the semiconductor substrate at a bottom surface of the opening; c. a step of forming a second antietching film on a whole surface of the semiconductor substrate by a reduced pressure CVD method and anisotropically etching the second antietching film to expose the first antietching film on a top surface and the semiconductor substrate at a bottom surface of the opening, said second antietching film being left only on a sidewall of the opening and covering said second antioxidation film; d. a step of performing isotropic dry etching using said first and second antietching films as masks; and e. a step of performing a heat treatment in an oxidizing atmosphere using said first and second antioxidation films as masks.

Claim 7

A method of fabricating a semiconductor device comprising: a. a step of forming an opening in a silicon substrate using a first silicon oxide film and a first silicon nitride film formed on said silicon substrate as masks; b. a step of a forming a second silicon nitride film on a whole surface of said semiconductor substrate by a reduced pressure CVD method and anisotropically etching the second silicon nitride film to expose the first silicon oxide film on a top surface and the semiconductor substrate at a bottom surface of the opening; c. a step of forming a second silicon oxide film by a reduced pressure CVD method and anisotropically etching the second silicon oxide film to expose the first silicon oxide film on a top surface and the semiconductor substrate at a bottom surface of the opening, said second silicon oxide film being left only on a sidewall of the opening and covering said second silicon nitride film; d. a step of performing isotropic dry etch-using said first and second silicon oxide films as masks; and e. a step of performing a heat treatment in an oxidizing atmosphere using said first and second silicon nitride films as masks.

Claim 8

A method of fabricating a semiconductor device comprising: a. a step of forming an opening in a silicon substrate using a first silicon oxide film and a first silicon nitride film formed on said silicon substrate as masks; b. a step of a forming a second silicon nitride film on a whole surface of said semiconductor substrate by a reduced pressure CVD method and anisotropically etching the second silicon nitride film to expose the first silicon oxide film on a top surface and the semiconductor substrate at a bottom surface of the opening; c. a step of forming a second silicon oxide film by a reduced pressure CVD method and anisotropically etching the second silicon oxide film to expose the first silicon oxide film on a top surface and the semiconductor substrate at a bottom surface of the opening, said second silicon oxide film being left only on a sidewall of the opening and covering said second silicon nitride film; d. a step of performing isotropic dry etch-using said first and second silicon oxide films as masks; and e. a step of performing a heat treatment in an oxidizing atmosphere using said first and second silicon nitride films as masks.