Semiconductor device comprising a void portion in an insulation film and method for manufacturing a semiconductor device comprising a void portion in an insulating film
A change in electrical characteristics of a semiconductor device including an interlayer insulating film over a transistor including an oxide semiconductor as a semiconductor film is suppressed. The structure includes a first insulating film which includes a void portion in a step region formed by a source electrode and a drain electrode over the semiconductor film and contains silicon oxide as a component, and a second insulating film containing silicon nitride, which is provided in contact with the first insulating film to cover the void portion in the first insulating film. The structure can prevent the void portion generated in the first insulating film from expanding outward.
1. A semiconductor device comprising:
an oxide semiconductor film;
a conductive film on and in contact with the oxide semiconductor film;
a first insulating film covering the conductive film, a side end surface of the conductive film, and the oxide semiconductor film; and
a second insulating film on and in contact with the first insulating film,
wherein the first insulating film comprises a void portion due to a step of the side end surface of the conductive film, and
wherein the second insulating film covers the void portion of the first insulating film.
2. The semiconductor device according to claim 1 ,
wherein the first insulating film comprises silicon and more oxygen than nitrogen, and
wherein the second insulating film comprises silicon and more nitrogen than oxygen.
3. The semiconductor device according to claim 1 ,
wherein the first insulating film is a silicon oxynitride film, and
wherein the second insulating film is a silicon nitride film.
4. The semiconductor device according to claim 1 ,
wherein the first insulating film is a silicon oxide film, and
wherein the second insulating film is a silicon nitride film.
5. The semiconductor device according to claim 1 ,
wherein the first insulating film has a thickness larger than the second insulating film.
6. The semiconductor device according to claim 1 ,
wherein the first insulating film has a density higher than or equal to 2.26 g/cm 3 and lower than or equal to 2.50 g/cm 3 .
7. A display device comprising the semiconductor device according to claim 1 .
8. A semiconductor device comprising:
an oxide semiconductor film;
a conductive film on and in contact with the oxide semiconductor film;
a first insulating film covering the conductive film, a side end surface of the conductive film, and the oxide semiconductor film; and
a second insulating film on and in contact with the first insulating film,
wherein the first insulating film comprises a void portion due to a step of the side end surface of the conductive film,
wherein the second insulating film covers the void portion of the first insulating film, and
wherein the first insulating film comprises a stack of a first oxide insulating film and a second oxide insulating film.
9. The semiconductor device according to claim 8 ,
wherein the first oxide insulating film and the second oxide insulating film are silicon oxynitride films, and
wherein the second insulating film is a silicon nitride film.
10. The semiconductor device according to claim 8 ,
wherein the second oxide insulating film is interposed between the first oxide insulating film and the second insulating film,
wherein the second oxide insulating film has a thickness larger than the first oxide insulating film, and
wherein the first insulating film has a thickness larger than the second insulating film.
11. The semiconductor device according to claim 8 ,
wherein the first insulating film has a density higher than or equal to 2.26 g/cm 3 and lower than or equal to 2.50 g/cm 3 .
12. The semiconductor device according to claim 8 ,
wherein the second oxide insulating film is denser than the first oxide insulating film.
13. A display device comprising the semiconductor device according to claim 8 .
14. A method for manufacturing a semiconductor device, comprising the steps of:
forming an oxide semiconductor film;
forming a conductive film on and in contact with the oxide semiconductor film;
forming a first insulating film covering the conductive film, a side end surface of the conductive film, and the oxide semiconductor film; and
forming a second insulating film on and in contact with the first insulating film,
wherein the first insulating film comprises a void portion due to a step of the side end surface of the conductive film, and
wherein the second insulating film covers the void portion of the first insulating film.
15. The semiconductor device according to claim 14 ,
wherein the first insulating film comprises a stack of a first oxynitride film and a second oxynitride film on and in contact with the first oxynitride film,
wherein the first oxynitride film is formed by a plasma CVD method under a first pressure and with a first high-frequency power, and
wherein the second oxynitride film is formed by a plasma CVD method under a second pressure higher than the first pressure and with a second high-frequency power higher than the first high-frequency power.
16. The semiconductor device according to claim 14 ,
wherein the first insulating film comprises a stack of a first oxynitride film and a second oxynitride film on and in contact with the first oxynitride film,
wherein the first oxynitride film is formed by a plasma CVD method under a first pressure, a first substrate temperature, and with a first high-frequency power, and
wherein the second oxynitride film is formed by a plasma CVD method under a second pressure higher than the first pressure, a second substrate temperature equal to the first substrate temperature, and with a second high-frequency power higher than the first high-frequency power.
17. The semiconductor device according to claim 14 ,
wherein the second insulating film is a silicon nitride film.
18. The semiconductor device according to claim 14 ,
wherein the first insulating film has a thickness larger than the second insulating film.
19. The semiconductor device according to claim 14 ,
wherein the first insulating film has a density higher than or equal to 2.26 g/cm 3 and lower than or equal to 2.50 g/cm 3 .
20. The semiconductor device according to claim 15 ,
wherein the second oxynitride film is denser than the first oxynitride film.
21. The semiconductor device according to claim 16 ,
wherein the second oxynitride film is denser than the first oxynitride film.
22. A display device comprising the semiconductor device according to claim 14 .