Semiconductor device and method of manufacturing the same

摘要

To reduce variation among TFTs in manufacture of a semiconductor device including n-type thin film transistors and p-type thin film transistors. Further, another object of the present invention is to reduce the number of masks and manufacturing steps, and manufacturing time. A method of manufacturing a semiconductor device includes forming an island-shaped semiconductor layer of a first thin film transistor, then, forming an island-shaped semiconductor layer of the second thin film transistor. In the formation of the island-shaped semiconductor layer of the second thin film transistor, a gate insulating film in contact with the island-shaped semiconductor layer of the second thin film transistor is used as a protection film (an etching stopper film) for the island-shaped semiconductor layer of the first thin film transistor.