Transistor having source/drain with graded germanium concentration

摘要

There is provided a semiconductor device using a semiconductor thin film having high crystallinity, which is formed by a manufacturing method with high productivity. When active layers of an amorphous silicon film are crystallized, germanium is used as a catalytic element for facilitating crystallization. When a heat treatment is carried out in a state where the active layers are in contact with a germanium film through an opening portion provided in a mask insulating film, the active layers made of a polysilicon film are obtained by crystal growth in a lateral direction.