Manufacturing method of semiconductor device
It is an object to provide a manufacturing method of a structure of a thin film transistor including an oxide semiconductor film, in which threshold voltage at which a channel is formed is positive and as close to 0 V as possible. A protective insulating layer is formed to cover a thin film transistor including an oxide semiconductor layer that is dehydrated or dehydrogenated by first heat treatment, and second heat treatment at a temperature that is lower than that of the first heat treatment, in which the increase and decrease in temperature are repeated plural times, is performed, whereby a thin film transistor including an oxide semiconductor layer, in which threshold voltage at which a channel is formed is positive and as close to 0 V as possible without depending on the channel length, can be manufactured.
1. A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode layer over a substrate having an insulating surface;
forming a gate insulating layer over the gate electrode layer;
forming an oxide semiconductor layer over the gate insulating layer;
dehydrating or dehydrogenating the oxide semiconductor layer as a first treatment;
forming a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
forming an insulating layer on the oxide semiconductor layer; and
performing a heat treatment as a second treatment, after forming the insulating layer,
wherein a thickness of the oxide semiconductor layer is greater than or equal to 5 nm and less than or equal to 200 nm, and
wherein a treatment temperature of the second treatment is lower than a treatment temperature of the first treatment.
2. The manufacturing method of a semiconductor device according to claim 1 ,
wherein the step of dehydrating or dehydrogenating the oxide semiconductor layer is performed in a nitrogen atmosphere or a rare gas atmosphere.
3. The manufacturing method of a semiconductor device according to claim 1 ,
wherein a temperature of the step of dehydrating or dehydrogenating the oxide semiconductor layer is higher than or equal to 350° C. and lower than or equal to 750° C.
4. The manufacturing method of a semiconductor device according to claim 1 ,
wherein the insulating layer is a protective insulating layer.
5. The manufacturing method of a semiconductor device according to claim 1 ,
wherein the insulating layer is one of silicon oxide layer, a silicon nitride oxide layer, a silicon nitride layer, an aluminum oxide layer, an aluminum oxynitride layer, and an aluminum nitride layer.
6. The manufacturing method of a semiconductor device according to claim 1 ,
wherein the insulating layer contains silicon and nitride.
7. The manufacturing method of a semiconductor device according to claim 1 ,
wherein a temperature of the heat treatment is higher than or equal to 100° C. and lower than or equal to 300° C.
8. A manufacturing method of a semiconductor device comprising the steps of:
forming a gate electrode layer over a substrate having an insulating surface;
forming a gate insulating layer over the gate electrode layer;
forming an oxide semiconductor layer over the gate insulating layer;
dehydrating or dehydrogenating the oxide semiconductor layer as a first treatment;
forming a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
forming an insulating layer on the oxide semiconductor layer; and
performing a heat treatment as a second treatment, after forming the insulating layer,
wherein a thickness of the oxide semiconductor layer is greater than or equal to 5 nm and less than or equal to 200 nm,
wherein a treatment temperature of the second treatment is lower than a treatment temperature of the first treatment,
wherein the oxide semiconductor layer contains indium, gallium and zinc,
wherein the gate insulating layer is a stacked-layer structure of a first layer containing silicon and nitrogen and a second layer containing silicon and oxygen, and
wherein the insulating layer is a stacked-layer structure of a third layer containing silicon and oxygen and a fourth layer containing silicon and nitrogen over the third layer.
9. The manufacturing method of a semiconductor device according to claim 8 ,
wherein the step of dehydrating or dehydrogenating the oxide semiconductor layer is performed in a nitrogen atmosphere or a rare gas atmosphere.
10. The manufacturing method of a semiconductor device according to claim 8 ,
wherein a temperature of the step of dehydrating or dehydrogenating the oxide semiconductor layer is higher than or equal to 350° C. and lower than or equal to 750° C.
11. The manufacturing method of a semiconductor device according to claim 8 ,
wherein the insulating layer is a protective insulating layer.
12. The manufacturing method of a semiconductor device according to claim 8 ,
wherein the insulating layer is one of silicon oxide layer, a silicon nitride oxide layer, a silicon nitride layer, an aluminum oxide layer, an aluminum oxynitride layer, and an aluminum nitride layer.
13. The manufacturing method of a semiconductor device according to claim 8 ,
wherein the insulating layer contains silicon and nitride.
14. The manufacturing method of a semiconductor device according to claim 8 ,
wherein a temperature of the heat treatment is higher than or equal to 100° C. and lower than or equal to 300° C.