Patent ID: 7989275

Claim:
A manufacturing method of a thin film transistor comprising: forming a light-blocking film and a first resist mask over the light-blocking film; etching part of the light-blocking film using the first resist mask to form a light-blocking layer having a pattern; removing the first resist mask; forming a base film over the light-blocking layer; sequentially forming a first conductive film, a first insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film over the base film; forming a second resist mask by light exposure and development over the second conductive film; performing first etching on the second conductive film, the impurity semiconductor film, the semiconductor film, and the first insulating film using the second resist mask to expose at least the first conductive film; performing second etching in which part of the first conductive film is side-etched to form a gate electrode layer; after performing the second etching, forming a third resist mask over the second conductive film; and performing third etching on the second conductive film, the impurity semiconductor film, and part of the semiconductor film using the third resist mask to form source and drain electrode layers, source and drain region layers, and a semiconductor layer, wherein the first resist mask and the second resist mask are formed using the same photomask.