Method of manufacturing semiconductor device
A method of manufacturing a semiconductor device according to an embodiment of the present invention includes: forming a first insulating film on a semiconductor substrate; forming a mask with an opening of a predetermined pattern in the first insulating film; performing anisotropic etching on the semiconductor substrate with the mask used as an etching mask to form a trench; forming a second insulating film on a surface of an inner wall of the trench with the mask used as a selective oxidation mask; removing the mask; forming a conductive film on the semiconductor substrate to fill the trench with the conductive film; and etching back the conductive film until at least a surface of the semiconductor substrate is exposed.
1. A method of manufacturing a semiconductor device, comprising:
(a) forming a mask with an opening of a predetermined pattern which is made of a mask insulating film on a semiconductor substrates;
(b) forming a trench in the substrate using the mask as an etching mask;
(c) forming a gate insulating film on a surface of an inner wall of the trench with the mask used as a selective oxidation mask;
(d) removing the mask;
(e) forming a conductive film on the semiconductor substrate to fill the trench with the conductive film; and
(f) etching back the conductive film until at least a surface of the semiconductor substrate is exposed.
2. The method of manufacturing a semiconductor device according to claim 1 , wherein an etchant that does not remove the gate insulating film is used upon removing the mask.
3. The method of manufacturing a semiconductor device according to claim 1 , wherein the mask insulating film is made of silicon nitride and the gate insulating film is made of silicon oxide.
4. The method of manufacturing a semiconductor device according to claim 2 , wherein the mask insulating film is made of silicon nitride and the gate insulating film is made of silicon oxide.
5. The method of manufacturing a semiconductor device according to claim 1 , wherein an etching rate of the semiconductor substrate and an etching rate of the conductive film are substantially equal to each other.
6. The method of manufacturing a semiconductor device according to claim 1 , wherein the semiconductor substrate is made of single crystal silicon, and the conductive film is made of polycrystalline silicon.
7. The method of manufacturing a semiconductor device according to claim 5 , wherein the semiconductor substrate is made of single crystal silicon, and the conductive film is made of polycrystalline silicon.
8. The method of manufacturing a semiconductor device according to claim 1 , further comprising:
etching off a protrusion of the gate insulating film from the surface of the semiconductor substrate after etching back the conductive film.
9. The method of manufacturing a semiconductor device according to claim 2 , further comprising:
etching off a protrusion of the gate insulating film from the surface of the semiconductor substrate after etching back the conductive film.
10. The method of manufacturing a semiconductor device according to claim 5 , further comprising:
etching off a protrusion of the gate insulating film from the surface of the semiconductor substrate after etching back the conductive film.
11. The method of manufacturing a semiconductor device according to claim 1 , wherein the gate insulating film is formed to a thickness of approximately 500 Å.
12. The method of manufacturing a semiconductor device according to claim 1 , wherein the mask is removed with a phosphoric acid.
13. The method of manufacturing a semiconductor device according to claim 1 , wherein the mask insulating film is formed by chemical vapor deposition.
14. The method of manufacturing a semiconductor device according to claim 1 , wherein the mask is formed by photolithography and etching.
15. The method of manufacturing a semiconductor device according to claim 1 , wherein the gate insulating film is formed by thermal oxidation.
16. The method of manufacturing a semiconductor device according to claim 1 , wherein the conductive film is formed by chemical vapor deposition.
17. The method of manufacturing a semiconductor device according to claim 1 , wherein the conductive film is etched back using dry etching.
18. The method of manufacturing a semiconductor device according to claim 1 , wherein the removal of the mask exposes the surface of the semiconductor substrate.