Semiconductor device and manufacturing method thereof
A semiconductor device which includes an oxide semiconductor and has favorable electrical characteristics is provided. In the semiconductor device, an oxide semiconductor film and an insulating film are formed over a substrate. Side surfaces of the oxide semiconductor film are in contact with the insulating film. The oxide semiconductor film includes a channel formation region and regions containing a dopant between which the channel formation region is sandwiched. A gate insulating film is formed on and in contact with the oxide semiconductor film. A gate electrode with sidewall insulating films is formed over the gate insulating film. A source electrode and a drain electrode are formed in contact with the oxide semiconductor film and the insulating film.
1. A semiconductor device comprising:
a first insulating film having a projection portion and a depression portion over a substrate;
an oxide semiconductor film over the projection portion only of the first insulating film;
a second insulating film in the depression portion of the first insulating film;
a third insulating film over and in direct contact with the second insulating film;
a gate insulating film over and in direct contact with a top surface of the oxide semiconductor film;
a gate electrode over the gate insulating film;
a source electrode and a drain electrode over and in direct contact with the oxide semiconductor film, the second insulating film and the third insulating film; and
wherein the region of the first insulating film is surrounded by the depression portion,
wherein entire region of the third insulating film is located at a lower position than a top surface of the gate electrode,
wherein the top surface of the oxide semiconductor film is not covered by the second insulating film,
wherein the third insulating film is not in contact with the oxide semiconductor film,
wherein a side surface of the oxide semiconductor film is covered by and in direct contact with the second insulating film, and
wherein the oxide semiconductor film comprises a channel formation region and first regions containing a dopant between which the channel formation region is sandwiched.
2. The semiconductor device according to claim 1 , wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment.
3. The semiconductor device according to claim 1 , wherein the oxide semiconductor film comprises one or more elements selected from In, Ga, Sn, and Zn.
4. The semiconductor device according to claim 1 ,
wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment, and
wherein the third insulating film comprises aluminum oxide.
5. The semiconductor device according to claim 1 , wherein the dopant is at least one element selected from hydrogen, helium, neon, argon, krypton, xenon, nitrogen, phosphorus, arsenic, boron, and aluminum.
6. An electronic device comprising the semiconductor device according to claim 1 .
7. A semiconductor device comprising:
a first insulating film having a projection portion and a depression portion over a substrate;
an oxide semiconductor film over the projection portion only of the first insulating film;
a second insulating film in the depression portion of the first insulating film;
a third insulating film over and in direct contact with the second insulating film;
a gate insulating film over and in direct contact with a top surface of the oxide semiconductor film;
a gate electrode over the gate insulating film; and
a source electrode and a drain electrode over the oxide semiconductor film, the second insulating film and the third insulating film,
wherein the region of the first insulating film is surrounded by the depression portion,
wherein entire region of the third insulating film is located at a lower position than a top surface of the gate electrode,
wherein the top surface of the oxide semiconductor film is not covered by the second insulating film,
wherein the third insulating film is not in contact with the oxide semiconductor film,
wherein a side surface of the oxide semiconductor film is covered by and in direct contact with the second insulating film,
wherein the oxide semiconductor film comprises a channel formation region, first regions containing a dopant between which the channel formation region is sandwiched, and second regions containing the dopant between which the first regions are sandwiched, and
wherein a dopant concentration of the first regions is different from a dopant concentration of the second regions.
8. The semiconductor device according to claim 7 , further comprising:
sidewall insulating films in direct contact with the gate electrode,
wherein the first regions overlap with the sidewall insulating films, and
wherein the dopant concentration of the first regions is lower than the dopant concentration of the second regions.
9. The semiconductor device according to claim 7 , wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment.
10. The semiconductor device according to claim 7 , wherein the oxide semiconductor film comprises one or more elements selected from In, Ga, Sn, and Zn.
11. The semiconductor device according to claim 7 ,
wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment, and
wherein the third insulating film comprises aluminum oxide.
12. The semiconductor device according to claim 7 , wherein the dopant is at least one element selected from hydrogen, helium, neon, argon, krypton, xenon, nitrogen, phosphorus, arsenic, boron, and aluminum.
13. An electronic device comprising the semiconductor device according to claim 7 .
14. A semiconductor device comprising:
a first insulating film having a projection portion and a depression portion over a substrate;
an oxide semiconductor film over the projection portion only of the first insulating film;
a second insulating film in the depression portion of the first insulating film;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a first conductive film over and in direct contact with the oxide semiconductor film and the second insulating film; and
a second conductive film over and in direct contact with the first conductive film,
wherein the region of the first insulating film is surrounded by the depression portion,
wherein a width of the first conductive film is larger than a width of the second conductive film,
wherein a side surface of the oxide semiconductor film is covered by and in direct contact with the second insulating film, and
wherein the oxide semiconductor film comprises a channel formation region and regions containing a dopant between which the channel formation region is sandwiched.
15. The semiconductor device according to claim 14 , further comprising:
sidewall insulating films in direct contact with the gate electrode,
wherein the first conductive film is in contact with the sidewall insulating films.
16. The semiconductor device according to claim 15 , wherein the first conductive film is thinner than the second conductive film.
17. The semiconductor device according to claim 14 , wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment.
18. The semiconductor device according to claim 14 , wherein the oxide semiconductor film comprises one or more elements selected from In, Ga, Sn, and Zn.
19. The semiconductor device according to claim 14 , further comprising:
a third insulating film over and in direct contact with the second insulating film,
wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment, and
wherein the third insulating film comprises aluminum oxide.
20. The semiconductor device according to claim 14 , wherein the dopant is at least one element selected from hydrogen, helium, neon, argon, krypton, xenon, nitrogen, phosphorus, arsenic, boron, and aluminum.
21. An electronic device comprising the semiconductor device according to claim 14 .
22. A semiconductor device comprising:
a first insulating film having a projection portion and a depression portion over a substrate;
an oxide semiconductor film over the projection portion only of the first insulating film;
a second insulating film in the depression portion of the first insulating film;
a gate insulating film over the oxide semiconductor film;
a gate electrode over the gate insulating film;
a first conductive film over and in direct contact with the oxide semiconductor film and the second insulating film; and
a second conductive film over and in direct contact with the first conductive film,
wherein the region of the first insulating film is surrounded by the depression portion,
wherein a width of the first conductive film is larger than a width of the second conductive film,
wherein a side surface of the oxide semiconductor film is covered by and in direct contact with the second insulating film,
wherein the oxide semiconductor film comprises a channel formation region, first regions containing a dopant between which the channel formation region is sandwiched, and second regions containing the dopant between which the first regions containing the dopant are sandwiched, and
wherein a dopant concentration of the first regions is different from a dopant concentration of the second regions.
23. The semiconductor device according to claim 22 , further comprising:
sidewall insulating films in direct contact with the gate electrode,
wherein the dopant concentration of the first regions is lower than the dopant concentration of the second regions.
24. The semiconductor device according to claim 22 , further comprising:
sidewall insulating films in direct contact with the gate electrode,
wherein the first conductive film is in contact with the sidewall insulating films.
25. The semiconductor device according to claim 24 , wherein the first conductive film is thinner than the second conductive film.
26. The semiconductor device according to claim 22 , wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment.
27. The semiconductor device according to claim 22 , wherein the oxide semiconductor film comprises one or more elements selected from In, Ga, Sn, and Zn.
28. The semiconductor device according to claim 22 , further comprising:
a third insulating film over and in direct contact with the second insulating film,
wherein the second insulating film comprises an insulating material from which oxygen is released by heat treatment, and
wherein the third insulating film comprises aluminum oxide.
29. The semiconductor device according to claim 22 , wherein the dopant is at least one element selected from hydrogen, helium, neon, argon, krypton, xenon, nitrogen, phosphorus, arsenic, boron, and aluminum.
30. An electronic device comprising the semiconductor device according to claim 22 .
31. The semiconductor device according to claim 1 , further comprising:
a fourth insulating film over and in direct contact with an upper surface of the source electrode, an upper surface of the drain electrode, the second insulating film, and the third insulating film.
32. The semiconductor device according to claim 7 , further comprising:
a fourth insulating film over and in direct contact with an upper surface of the source electrode, an upper surface of the drain electrode, the second insulating film, and the third insulating film.
33. The semiconductor device according to claim 14 ,
wherein the first conductive film is a source electrode or a drain electrode.
34. The semiconductor device according to claim 22 ,
wherein the first conductive film is a source electrode or a drain electrode.