Method of fabricating semiconductor device

• US 4,845,048 A
• Filed: 11/07/1988
• Issued: 07/04/1989
• Est. Priority Date: 06/12/1986
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tamaki, Tokuhiko, Kubota, Masafumi
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): Pawlikowski, Beverly A.
• Application Number:
  US07/268,604
• Time in Patent Office: 239 Days
• Field of Search: 437/65, 437/76, 437/67, 156/644, 156/650, 148/DIG. 43
• US Class Current: 438/410
• CPC Class Codes: H01L 21/32 using masks
• CPC Class Codes: H01L 21/76264 SOI together with lateral isolation, e.g. using local oxidation of silicon, or dielectric or polycristalline material refilled trench or air gap isolation regions, e.g. completely isolated semiconductor islands
• CPC Class Codes: H01L 21/76281 Lateral isolation by selective oxidation of silicon
• CPC Class Codes: Y10S 148/043 Dual dielectric
• CPC Class Codes: Y10S 148/051 Etching
• CPC Class Codes: Y10S 148/117 Oxidation, selective

Abstract

A method of fabricating a semiconductor device which includes:

(1) a step of forming an opening in a silicon substrate using a first silicon oxide film and a first silicon nitride film formed on the silicon substrate as masks,

(2) a step of forming a second silicon oxide film and a second silicon nitride film on the side wall of the opening by the reduced pressure CVD method and anisotropic etching method,

(3) a step of performing isotropic dry etching using the first and second silicon oxide films as masks, and

(4) a step of performing heat treatment in an oxidizing atmosphere using the first and second silicon nitride films as masks.

Thereby, uniform isotropic etching may be accomplished by use of the dry etching method.

Claims

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.

2. The method of fabricating a semiconductor device according to claim 1, wherein step d. is performed by microwave discharge using CF₄, O₂ gas.

3. The method of fabricating a semiconductor device according to claim 1, wherein a silicon oxide film is used as the first and second antietching films.

4. The method of fabricating a semiconductor device according to claim 1, wherein a silicon nitride film is used as the first and second antioxidation films.

5. The method of fabricating a semiconductor device according to claim 1, wherein the semiconductor substrate is subjected to anisotropic etching at the bottom surface of the opening, using the first and second antietching films as masks, and then to isotropic etching.

6. 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.