Method for fabricating a semiconductor device having a tapered-mesa side-wall film

1. A method for fabricating a semiconductor device comprising, in consecutive order:

depositing a metallic conductive film on an underlying insulating film;

consecutively depositing first and second insulator films on said metallic conductive film;

patterning said first and second insulator films to have a substantially same patterned area;

etching said second insulator film selectively from said first insulator film to configure said second insulator film to have a bottom with a width smaller than a width of said first insulator film;

patterning said metallic conductive film by using said first and second insulator films as an etching mask;

subsequently depositing a third insulator film on said first insulator film, said etched second insulator film, and said underlying insulating film;

etching-back said third insulator film to configure a side-wall film covering at least said patterned metallic conductive film; and

depositing a fourth insulator film to embed therein said side-wall film on said underlying insulating film.

2. The method according to claim 1 , wherein said etching-back configures said side-wall film to have a tapered mesa structure having a larger width toward a bottom thereof.

3. The method according to claim 1 , further comprising, after depositing said fourth insulator film:

etching said fourth insulator film to form therein a contact hole by using said side-wall film as an etch stopper; and

forming a contact plug in said contact hole.

4. The method according to claim 1 , wherein said first and second insulator films comprise a nitride film and an oxide film, respectively.

5. The method according to claim 1 , wherein said semiconductor device comprises a semiconductor memory device.

6. The method of claim 1 , wherein etching said second insulator film selectively from said first insulator film comprises wet etching said second insulator film.

7. A method for fabricating a semiconductor device comprising, in consecutive order:

depositing a metallic conductive film on an underlying insulating film;

consecutively depositing first and second insulator films on said metallic conductive film;

patterning said first and second insulator films to have a substantially same patterned area;

patterning said metallic conductive film by using said first and second insulator films as an etching mask;

etching said second insulator film selectively from said first insulator film to configure said second insulator film to have a bottom with a width smaller than a width of said first insulator film;

subsequently depositing a third insulator film on said first insulator film, said etched second insulator film, and said underlying insulating film;

etching-back said third insulator film to configure a side-wall film covering at least said patterned metallic conductive film; and

depositing a fourth insulator film to embed therein said side-wall film on said underlying insulating film.

8. The method according to claim 7 , wherein said etching-back configures said side-wall film to have a tapered mesa structure having a larger width toward a bottom thereof.

9. The method according to claim 7 , further comprising, after depositing said fourth insulator film:

etching said fourth insulator film to form therein a contact hole by using said side-wall film as an etch stopper; and

forming a contact plug in said contact hole.

10. The method according to claim 7 , wherein said first and second insulator films comprise a nitride film and an oxide film, respectively.

11. The method according to claim 7 , wherein said semiconductor device comprises a semiconductor memory device.

12. The method of claim 7 , wherein etching said second insulator film selectively from said first insulator film comprises wet etching said second insulator film.

13. A method for fabricating a semiconductor device, the method comprising:

depositing a metallic conductive film on an insulating film;

depositing a first insulator film on said metallic conductive film;

depositing a second insulator film on said first insulator film;

patterning said first and second insulator films;

etching said second insulator film to have a patterned area that is smaller than said first insulator film;

patterning said metallic conductive film;

subsequently depositing a third insulator film on said first insulator film, said etched second insulator film, and said insulating film; and

forming a sidewall film by etching said third insulator film.

14. The method of claim 13 , wherein said etching of said second insulator film is performed before said patterning of said metallic conductive film.

15. The method of claim 13 , wherein said etching of said second insulator film is performed after said patterning of said metallic conductive film.

16. The method of claim 13 , wherein said patterning said metallic conductive film uses said first and second insulator films as an etching mask.

17. The method of claim 13 , wherein said sidewall film covers at least said patterned metallic conductive film.

18. The method of claim 17 , further comprising depositing a fourth insulator film on said sidewall film and said underlying insulating film.

19. The method of claim 18 , further comprising etching said fourth insulator film to form a contact hole.

20. The method of claim 19 , wherein etching said fourth insulator film uses said sidewall film as an etch stopper.

21. The method of claim 19 , further comprising forming a contact plug in said contact hole.

22. The method of claim 13 , wherein said sidewall film comprises a tapered mesa structure having a width larger at the bottom.

23. The method of claim 13 , wherein said first insulator film comprises a nitride film.

24. The method of claim 13 , wherein said second insulator film comprises an oxide film.

25. The method of claim 13 , wherein said semiconductor device comprises a semiconductor memory device.

26. The method of claim 13 , wherein etching said second insulator film comprises wet etching said second insulator film.