Patent ID: 8883554

Claim:
A method for manufacturing a semiconductor device, comprising the steps of: forming a gate electrode layer having a light-blocking property over a first surface of a substrate; forming a gate insulating film over the gate electrode layer; forming an island-shaped oxide semiconductor layer having a light-transmitting property over the gate insulating film; forming an insulating layer over the island-shaped oxide semiconductor layer; forming a positive photosensitive thin film over the insulating layer; performing light exposure on the positive photosensitive thin film by irradiation with light from a side of the substrate opposite to the first surface; removing an exposed region of the positive photosensitive thin film by development; forming a channel protective layer by etching the insulating layer with the use of an unexposed region of the positive photosensitive thin film as a mask; and forming a wiring layer over the island-shaped oxide semiconductor layer.