Claims
- 1. A fabrication method of a semiconductor device having a trench type element isolation structure, comprising:
- a first step of forming a first oxide film on a semiconductor substrate;
- a second step of forming an easily oxidizable film on said first oxide film;
- a third step of forming an anti-oxidation insulating film on said easily oxidizable film;
- a fourth step of patterning said anti-oxidation insulating film;
- a fifth step of etching said easily oxidizable film, said first oxide film and said semiconductor substrate using said patterned anti-oxidation insulating film as a mask to thereby form a trench in said easily oxidizable film, said first oxide film and said semiconductor substrate;
- a sixth step of oxidizing an exposed portion of said easily oxidizable film, which is exposed from a side surface of said trench, to thereby form a second oxide film, and oxidizing an exposed portion of said semiconductor substrate, which is exposed from bottom and side surfaces of said trench, to thereby form a third oxide film;
- a seventh step of forming a fourth oxide film on said anti-oxidation insulating film in such a manner that said trench is buried by said fourth oxide film;
- an eighth step of polishing said fourth oxide film to thereby expose said anti-oxidation insulating film; and
- a ninth step of removing said anti-oxidization film, said easily oxidizable film and said first oxide film to thereby form an element isolation oxide film containing at least said second to fourth oxide films.
- 2. A fabrication method of a semiconductor device as claimed in claim 1, wherein:
- said first to third oxide films are thermal oxide films;
- said easily oxidizable film is one of a polycrystalline silicon film and an amorphous silicon film;
- said anti-oxidation insulating film is a silicon nitride film; and
- said fourth oxide film is a chemical-vapor-deposited silicon dioxide film.
- 3. A fabrication method of a semiconductor device as claimed in claim 2, wherein said ninth step includes a step of anisotropic-etching said easily oxidizable film and said first oxide film in a batch manner.
- 4. A fabrication method of a semiconductor device as claimed in claim 2, wherein said ninth step includes a step of anisotropic-etching said easily oxidizable film and a step of isotropic-etching said first oxide film.
- 5. A fabrication method of a semiconductor device as claimed in claim 1, further comprising a tenth step of forming a transistor at an element forming region defined by said element isolation oxide film.
- 6. A fabrication method of a semiconductor device having a trench type element isolation structure, comprising:
- a first step of forming a first oxide film on a semiconductor substrate;
- a second step of forming an easily oxidizable film on said first oxide film;
- a third step of forming an anti-oxidation insulating film on said easily oxidizable film;
- a fourth step of patterning said anti-oxidation insulating film;
- a fifth step of etching said easily oxidizable film, said first oxide film and said semiconductor substrate using said patterned anti-oxidation insulating film as a mask to thereby form a trench in said easily oxidizable film, said first oxide film and said semiconductor substrate;
- a sixth step of oxidizing an exposed portion of said easily oxidizable film, which is exposed from a side surface of said trench, to thereby form a second oxide film, and oxidizing an exposed portion of said semiconductor substrate, which is exposed from bottom and side surfaces of said trench, to thereby form a third oxide film;
- a seventh step of forming a fourth oxide film on said anti-oxidation insulating film in such a manner that said trench is buried by said fourth oxide film;
- an eighth step of polishing said fourth oxide film to thereby expose said anti-oxidation insulating film; and
- a ninth step of removing said anti-oxidization film and said easily oxidizable film.
- 7. The method of claim 1 wherein in said ninth step, said first oxide film and said easily oxidizable film remain in areas under said second oxide film.
- 8. The method of claim 7 wherein said ninth step further comprises etching a top surface of said fourth oxide film to form a projection portion with substantially vertical sidewalls.
- 9. The method of claim 3 wherein said fourth oxide film is also etched by said anisotropic-etching.
- 10. The method of claim 4 further comprising etching said fourth oxide film along with said first oxide film.
- 11. The method of claim 10 wherein said fourth oxide film has a higher etch rate than said first oxide film.
- 12. The method of claim 10 wherein said fourth oxide film is etched to have a substantially convex shape.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-123053 |
Apr 1997 |
JPX |
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Parent Case Info
This application is a divisional of application Ser. No. 09/038,111 filed Mar. 11, 1998 now U.S. Pat. No. 6,020,622.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5234861 |
Roisen et al. |
Aug 1993 |
|
6017800 |
Sayama et al. |
Jan 2000 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
038111 |
Mar 1998 |
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