Semiconductor device and manufacturing method thereof
The semiconductor device includes a gate electrode over a substrate, a gate insulating layer over the gate electrode, an oxide semiconductor layer over the gate insulating layer, and a source electrode and a drain electrode over the oxide semiconductor layer. A length of part of an outer edge of the oxide semiconductor layer from an outer edge of the source electrode to an outer edge of the drain electrode is more than three times, preferably more than five times as long as a channel length of the semiconductor device. Further, oxygen is supplied from the gate insulating layer to the oxide semiconductor layer by heat treatment. In addition, an insulating layer is formed after the oxide semiconductor layer is selectively etched.
1. A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating layer over the gate electrode;
forming an oxide semiconductor layer over the gate insulating layer;
performing heat treatment on the oxide semiconductor layer;
forming a source electrode and a drain electrode over the oxide semiconductor layer after the heat treatment;
forming a resist mask over the oxide semiconductor layer;
performing etching on the oxide semiconductor layer using the resist mask; and
forming an insulating layer so as to cover the oxide semiconductor layer, the source electrode, and the drain electrode after performing the etching,
wherein the resist mask overlaps with the gate electrode, the source electrode and the drain electrode, and
wherein part of the source electrode and part of the drain electrode, the part not overlapping with the resist mask, are also used as masks for the etching.
2. The method for manufacturing a semiconductor device, according to claim 1 , wherein the gate insulating layer contains excessive oxygen with respect to a stoichiometry proportion.
3. The method for manufacturing a semiconductor device, according to claim 1 , wherein oxygen is supplied from the gate insulating layer to the oxide semiconductor layer by the heat treatment.
4. The method for manufacturing a semiconductor device, according to claim 1 , wherein the heat treatment is performed at higher than or equal to 300° C. and lower than or equal to 450° C.
5. The method for manufacturing a semiconductor device, according to claim 1 , wherein the oxide semiconductor layer comprises at least one element selected from In, Ga, Sn, and Zn.
6. The method for manufacturing a semiconductor device, according to claim 1 , wherein the oxide semiconductor layer is non-single-crystal.
7. A method for manufacturing a semiconductor device, comprising the steps of:
forming a gate electrode over a substrate;
forming a gate insulating layer over the gate electrode;
forming an oxide semiconductor layer over the gate insulating layer;
forming a first insulating layer overlapping with the gate insulating layer with the oxide semiconductor layer interposed therebetween;
performing heat treatment on the oxide semiconductor layer and the first insulating layer;
forming a source electrode and a drain electrode over the oxide semiconductor layer and the first insulating layer;
forming a resist mask over the oxide semiconductor layer, the first insulating layer, the source electrode and the drain electrode;
performing etching on the oxide semiconductor layer using the resist mask; and
forming a second insulating layer so as to cover the oxide semiconductor layer after performing the etching,
wherein the resist mask overlaps with the gate electrode, and
wherein part of the source electrode and part of the drain electrode are also used as masks for the etching.
8. The method for manufacturing a semiconductor device, according to claim 7 , wherein the gate insulating layer contains excessive oxygen with respect to a stoichiometry proportion.
9. The method for manufacturing a semiconductor device, according to claim 7 , wherein oxygen is supplied from the gate insulating layer and the first insulating layer to the oxide semiconductor layer by the heat treatment.
10. The method for manufacturing a semiconductor device, according to claim 7 , wherein the heat treatment is performed at higher than or equal to 300° C. and lower than or equal to 450° C.
11. The method for manufacturing a semiconductor device, according to claim 7 , wherein the oxide semiconductor layer comprises at least one element selected from In, Ga, Sn, and Zn.
12. The method for manufacturing a semiconductor device, according to claim 7 , wherein the oxide semiconductor layer is non-single-crystal.