Display device and method for manufacturing the same
An object is to provide a display device with excellent display characteristics, where a pixel circuit and a driver circuit provided over one substrate are formed using transistors which have different structures corresponding to characteristics of the respective circuits. The driver circuit portion includes a driver circuit transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using a metal film, and a channel layer is formed using an oxide semiconductor. The pixel portion includes a pixel transistor in which a gate electrode layer, a source electrode layer, and a drain electrode layer are formed using an oxide conductor, and a semiconductor layer is formed using an oxide semiconductor. The pixel transistor is formed using a light-transmitting material, and thus, a display device with higher aperture ratio can be manufactured.
1. A method for manufacturing a semiconductor device, comprising the steps of:
forming an oxide semiconductor layer over an insulating layer;
forming a source electrode layer and a drain electrode layer over and in contact with a first region of the oxide semiconductor layer;
forming an oxide insulating layer over and in contact with a second region of the oxide semiconductor layer; and
performing a heat treatment on the oxide insulating layer so that oxygen in the oxide insulating layer is supplied to the second region of the oxide semiconductor layer,
wherein a conductivity of the first region of the oxide semiconductor layer is higher than a conductivity of the second region of the oxide semiconductor layer.
2. The method for manufacturing a semiconductor device according to claim 1 , further comprising a step of performing a heat treatment on the oxide semiconductor layer before the step of forming the oxide insulating layer.
3. The method for manufacturing a semiconductor device according to claim 1 , further comprising a step of performing a heat treatment on the oxide semiconductor layer under an atmosphere including nitrogen before the step of forming the oxide insulating layer.
4. The method for manufacturing a semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises indium, gallium, and zinc.
5. The method for manufacturing a semiconductor device according to claim 1 , wherein the oxide semiconductor layer comprises indium, tin, and zinc.
6. The method for manufacturing a semiconductor device according to claim 1 ,
wherein the first region is an n-type region, and
wherein the second region is an i-type region.
7. The method for manufacturing a semiconductor device according to claim 1 , wherein thickness of the oxide semiconductor layer is from 15 nm to 50 nm inclusive.
8. The method for manufacturing a semiconductor device according to claim 1 , wherein the semiconductor device includes a field effect transistor, a liquid crystal display device, a television device, a mobile phone, a camera, a portable information terminal, or a personal computer.
9. A method for manufacturing a semiconductor device, comprising the steps of:
forming an oxide semiconductor layer over an insulating layer;
performing a first heat treatment on the oxide semiconductor layer;
forming a source electrode layer and a drain electrode layer over and in contact with a first region of the oxide semiconductor layer;
forming an oxide insulating layer over and in contact with a second region of the oxide semiconductor layer; and
performing a second heat treatment on the oxide insulating layer so that oxygen in the oxide insulating layer is supplied to the second region of the oxide semiconductor layer,
wherein a conductivity of the first region of the oxide semiconductor layer is higher than a conductivity of the second region of the oxide semiconductor layer.
10. The method for manufacturing a semiconductor device according to claim 9 , wherein the first heat treatment is performed before the steps of forming the source electrode layer, the drain electrode layer, and the oxide insulating layer.
11. The method for manufacturing a semiconductor device according to claim 9 , wherein the first heat treatment is performed under an atmosphere including nitrogen.
12. The method for manufacturing a semiconductor device according to claim 9 , wherein a temperature of the first heat treatment is higher than a temperature of the second heat treatment.
13. The method for manufacturing a semiconductor device according to claim 9 , wherein the oxide semiconductor layer comprises indium, gallium, and zinc.
14. The method for manufacturing a semiconductor device according to claim 9 , wherein the oxide semiconductor layer comprises indium, tin, and zinc.
15. The method for manufacturing a semiconductor device according to claim 9 ,
wherein the first region is an n-type region, and
wherein the second region is an i-type region.
16. The method for manufacturing a semiconductor device according to claim 9 , wherein thickness of the oxide semiconductor layer is from 15 nm to 50 nm inclusive.
17. The method for manufacturing a semiconductor device according to claim 9 , wherein the semiconductor device includes a field effect transistor, a liquid crystal display device, a television device, a mobile phone, a camera, a portable information terminal, or a personal computer.