Method of fabricating semiconductor device

1. A method of fabricating a semiconductor device, comprising:

forming an interlayer sacrificial film and an insulating film located thereon above a semiconductor substrate having a semiconductor element, the interlayer sacrificial film having a wiring provided therein;

etching the insulating film, or, etching the insulating film and the interlayer sacrificial film to form a trench reaching the interlayer sacrificial film;

forming a gas permeable film in the trench;

gasifying and removing the interlayer sacrificial film through the trench and the gas permeable film; and

forming a sealing film on the gas permeable film for sealing the vicinity of an opening of the trench after removing the interlayer sacrificial film.

2. The method of fabricating a semiconductor device according to claim 1 , wherein, after forming a sacrificial film in the trench, the gas permeable film is formed on the sacrificial film in the trench; and

after gasifying and removing the sacrificial film through the trench and the gas permeable film, the interlayer sacrificial film is gasified and removed through the trench and the gas permeable film.

3. The method of fabricating a semiconductor device according to claim 2 , wherein the sacrificial film is gasified by chemical dry etching, ultraviolet irradiation or a thermal decomposition method.

4. The method of fabricating a semiconductor device according to claim 3 , wherein the sacrificial film comprises hydrocarbon.

5. The method of fabricating a semiconductor device according to claim 3 , wherein the interlayer sacrificial film is gasified by chemical dry etching or a thermal decomposition method.

6. The method of fabricating a semiconductor device according to claim 5 , wherein the sacrificial film and the interlayer sacrificial film are removed by the same treatment.

7. The method of fabricating a semiconductor device according to claim 6 , wherein the sacrificial film and the interlayer sacrificial film comprise hydrocarbon.

8. The method of fabricating a semiconductor device according to claim 2 , wherein a height of an upper surface of the sacrificial film is the same as or higher than a height of a bottom of the insulating film and lower than a height of an upper surface of the insulating film.

9. The method of fabricating a semiconductor device according to claim 1 , wherein the gas permeable film is formed so as to include a void therein.

10. The method of fabricating a semiconductor device according to claim 9 , wherein the gas permeable film is formed so as to have an overhang shape in the vicinity of the opening of the trench.

11. The method of fabricating a semiconductor device according to claim 1 , wherein the interlayer sacrificial film is gasified by chemical dry etching or a thermal decomposition method.

12. The method of fabricating a semiconductor device according to claim 11 , wherein the interlayer sacrificial film comprises hydrocarbon.

13. The method of fabricating a semiconductor device according to claim 1 , wherein the gas permeable film comprises a porous film.

14. The method of fabricating a semiconductor device according to claim 1 , wherein a height of an upper surface of the gas permeable film is the same as or higher than a height of a bottom of the insulating film and lower than a height of an upper surface of the insulating film.

15. The method of fabricating a semiconductor device according to claim 1 , wherein the trench is formed so that a bottom thereof reaches the same level as or lower than a bottom of the interlayer sacrificial film; and

the gas permeable film is formed so that a bottom thereof is in contact with the bottom of the trench.

16. A method of fabricating a semiconductor device, comprising:

forming a first interlayer sacrificial film and a first insulating film located thereon above a semiconductor substrate having a semiconductor element via a second interlayer sacrificial film and a second insulating film located thereon, the first interlayer sacrificial film having a first wiring provided therein and the second interlayer sacrificial film having a second wiring provided therein;

etching the first insulating film, the first interlayer sacrificial film and the second insulating film, or, etching the first insulating film, the first interlayer sacrificial film, the second insulating film and the second interlayer sacrificial film to form a trench reaching the second interlayer sacrificial film;

forming a gas permeable film in the trench;

gasifying and removing the first interlayer sacrificial film and the second interlayer sacrificial film through the trench and the gas permeable film; and

forming a sealing film on the gas permeable film for sealing the vicinity of an opening of the trench after removing the first interlayer sacrificial film and the second interlayer sacrificial film.

17. The method of fabricating a semiconductor device according to claim 16 , wherein the first interlayer sacrificial film and the second interlayer sacrificial film are gasified by chemical dry etching or a thermal decomposition method.

18. The method of fabricating a semiconductor device according to claim 17 , wherein the first interlayer sacrificial film and the second interlayer sacrificial film comprise hydrocarbon.

19. The method of fabricating a semiconductor device according to claim 16 , wherein a height of an upper surface of the gas permeable film is the same as or higher than a height of a bottom of the first insulating film and lower than a height of an upper surface of the first insulating film.

20. The method of fabricating a semiconductor device according to claim 16 , wherein the trench is formed so that the bottom thereof reaches the same level as or lower than a bottom of the second interlayer sacrificial film; and

the gas permeable film is formed so that a bottom thereof is in contact with the bottom of the trench.