Semiconductor device and method for manufacturing the same
View Patent ↗A transistor in which the state of an interface between an oxide semiconductor layer and an insulating film in contact with the oxide semiconductor layer is favorable and a method for manufacturing the transistor are provided. Nitrogen is added to the vicinity of the interface between the oxide semiconductor layer and the insulating film (gate insulating layer) in contact with the oxide semiconductor layer so that the state of the interface of the oxide semiconductor layer becomes favorable. Specifically, the oxide semiconductor layer has a concentration gradient of nitrogen, and a region containing much nitrogen is provided at the interface with the gate insulating layer. A region having high crystallinity can be formed in the vicinity of the interface with the oxide semiconductor layer by addition of nitrogen, whereby the interface state can be stable.
1. A semiconductor device comprising:
a gate electrode layer;
a first insulating layer in contact with the gate electrode layer;
an oxide semiconductor layer in contact with the first insulating layer; and
a second insulating layer in contact with the oxide semiconductor layer,
wherein the oxide semiconductor layer has a peak of a nitrogen concentration at an interface with the first insulating layer, and
wherein the first insulating layer contains nitrogen and has a peak of a nitrogen concentration at an interface with the oxide semiconductor layer.
2. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer has a concentration gradient of nitrogen, which becomes higher the closer to the first insulating layer, and has a concentration gradient of oxygen, which becomes higher the closer to the second insulating layer.
3. The semiconductor device according to claim 1 , wherein a region of the oxide semiconductor layer, which is in the vicinity of the interface with the first insulating layer, has higher crystallinity than other regions.
4. The semiconductor device according to claim 1 , wherein a nitrogen concentration of the oxide semiconductor layer in the vicinity of the interface with the first insulating layer is higher than or equal to 5×10 19 /cm 3 .
5. The semiconductor device according to claim 1 , wherein a nitrogen concentration of the oxide semiconductor layer in the vicinity of the interface with the second insulating layer is lower than or equal to 5×10 19 /cm 3 .
6. The semiconductor device according to claim 1 ,
wherein the oxide semiconductor layer has a peak of an oxygen concentration at an interface with the second insulating layer, and
wherein the second insulating layer contains oxygen and has a peak of an oxygen concentration at an interface with the oxide semiconductor layer.
7. The semiconductor device according to claim 1 , wherein at least part of the oxide semiconductor layer has crystallinity and is c-axis aligned.
8. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises indium and zinc.
9. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises at least a hexagonal wurtzite crystal structure.
10. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises indium, gallium and zinc.
11. The semiconductor device according to claim 1 , wherein the oxide semiconductor layer includes a crystalline region.
12. A semiconductor device comprising:
a gate electrode layer;
a first insulating layer in contact with the gate electrode layer;
an oxide semiconductor layer in contact with the first insulating layer, the oxide semiconductor layer comprising indium and zinc; and
a second insulating layer in contact with the oxide semiconductor layer,
wherein the oxide semiconductor layer has a peak of a nitrogen concentration at an interface with the first insulating layer, and
wherein the first insulating layer contains nitrogen and has a peak of a nitrogen concentration at an interface with the oxide semiconductor layer, and
wherein the oxide semiconductor layer includes a crystalline region, the crystalline region having a c-axis being substantially perpendicular to a surface of the oxide semiconductor layer.
13. The semiconductor device according to claim 12 , wherein the oxide semiconductor layer has a concentration gradient of nitrogen, which becomes higher the closer to the first insulating layer, and has a concentration gradient of oxygen, which becomes higher the closer to the second insulating layer.
14. The semiconductor device according to claim 12 , wherein a region of the oxide semiconductor layer, which is in the vicinity of the interface with the first insulating layer, has higher crystallinity than other regions.
15. The semiconductor device according to claim 12 , wherein a nitrogen concentration of the oxide semiconductor layer in the vicinity of the interface with the first insulating layer is higher than or equal to 5×10 19 /cm 3 .
16. The semiconductor device according to claim 12 , wherein a nitrogen concentration of the oxide semiconductor layer in the vicinity of the interface with the second insulating layer is lower than or equal to 5×10 19 /cm 3 .
17. The semiconductor device according to claim 12 ,
wherein the oxide semiconductor layer has a peak of an oxygen concentration at an interface with the second insulating layer, and
wherein the second insulating layer contains oxygen and has a peak of an oxygen concentration at an interface with the oxide semiconductor layer.
18. The semiconductor device according to claim 12 , wherein at least part of the oxide semiconductor layer has crystallinity and is c-axis aligned.
19. The semiconductor device according to claim 12 , wherein the oxide semiconductor layer comprises at least a hexagonal wurtzite crystal structure.
20. The semiconductor device according to claim 12 , wherein the oxide semiconductor layer further comprises gallium.