Semiconductor device
In a transistor including an oxide semiconductor, hydrogen in the oxide semiconductor leads to degradation of electric characteristics of the transistor. Thus, an object is to provide a semiconductor device having good electrical characteristics. An insulating layer in contact with an oxide semiconductor layer where a channel region is formed is formed by a plasma CVD method using a silicon halide. The insulating layer thus formed has a hydrogen concentration less than 6×10 20 atoms/cm 3 and a halogen concentration greater than or equal to 1×10 20 atoms/cm 3 ; accordingly, hydrogen diffusion into the oxide semiconductor layer can be prevented and hydrogen in the oxide semiconductor layer is inactivated or released from the oxide semiconductor layer by the halogen, whereby a semiconductor device having good electrical characteristics can be provided.
1. A semiconductor device comprising:
an insulating layer;
an oxide semiconductor layer on the insulating layer;
a gate insulating layer over the oxide semiconductor layer, a part of the gate insulating layer is in contact with the oxide semiconductor layer; and
a gate electrode layer over the gate insulating layer,
wherein a hydrogen concentration in the insulating layer is less than 6×10 20 atoms/cm 3 and a halogen concentration in the insulating layer is greater than or equal to 1×10 20 atoms/cm 3 .
2. The semiconductor device according to claim 1 , wherein the insulating layer is an oxide insulating layer.
3. The semiconductor device according to claim 1 , wherein the gate insulating layer comprises silicon oxide, silicon oxynitride, silicon nitride oxide, hafnium oxide, aluminum oxide, or tantalum oxide.
4. The semiconductor device according to claim 1 , wherein a thickness of the insulating layer is five or more times as thick as a total thickness of the oxide semiconductor layer and the gate insulating layer.
5. The semiconductor device according to claim 1 , wherein the insulating layer is provided between a substrate and the oxide semiconductor layer.
6. The semiconductor device according to claim 1 , wherein the halogen is fluorine.
7. The semiconductor device according to claim 1 , wherein the insulating layer is formed by a plasma CVD method using a silicon halide.
8. A semiconductor device comprising:
an insulating layer;
an oxide semiconductor layer on the insulating layer;
a gate insulating layer over the oxide semiconductor layer, a part of the gate insulating layer is in contact with the oxide semiconductor layer; and
a gate electrode layer over the gate insulating layer,
wherein a hydrogen concentration in the insulating layer is less than 6×10 20 atoms/cm 3 and a halogen concentration in the insulating layer is greater than or equal to 1×10 20 atoms/cm 3 , and
wherein a hydrogen concentration in the gate insulating layer is less than 6×10 20 atoms/cm 3 and a halogen concentration in the gate insulating layer is greater than or equal to 1×10 20 atoms/cm 3 .
9. The semiconductor device according to claim 8 , wherein the insulating layer is an oxide insulating layer.
10. The semiconductor device according to claim 8 , wherein the gate insulating layer comprises silicon oxide, silicon oxynitride, silicon nitride oxide, hafnium oxide, aluminum oxide, or tantalum oxide.
11. The semiconductor device according to claim 8 , wherein a thickness of the insulating layer is five or more times as thick as a total thickness of the oxide semiconductor layer and the gate insulating layer.
12. The semiconductor device according to claim 8 , wherein the insulating layer is provided between a substrate and the oxide semiconductor layer.
13. The semiconductor device according to claim 8 , wherein the halogen is fluorine.
14. The semiconductor device according to claim 8 , wherein the insulating layer is formed by a plasma CVD method using a silicon halide.
15. A semiconductor device comprising:
an oxide semiconductor layer;
a gate electrode layer;
a gate insulating layer formed between the gate electrode layer and the oxide semiconductor layer; and
an insulating layer that faces the gate insulating layer with the oxide semiconductor layer interposed therebetween, the insulating layer being in contact with the oxide semiconductor layer,
wherein a hydrogen concentration in the insulating layer is less than 6×10 20 atoms/cm 3 and a halogen concentration in the insulating layer is greater than or equal to 1×10 20 atoms/cm 3 , and
wherein the insulating layer is formed by a plasma CVD method using a silicon halide.
16. The semiconductor device according to claim 15 , wherein the insulating layer is an oxide insulating layer.
17. The semiconductor device according to claim 15 , wherein the gate insulating layer comprises silicon oxide, silicon oxynitride, silicon nitride oxide, hafnium oxide, aluminum oxide, or tantalum oxide.
18. The semiconductor device according to claim 15 , wherein a thickness of the insulating layer is five or more times as thick as a total thickness of the oxide semiconductor layer and the gate insulating layer.
19. The semiconductor device according to claim 15 , wherein the insulating layer is provided between a substrate and the oxide semiconductor layer.
20. The semiconductor device according to claim 15 , wherein the halogen is fluorine.