| abstract |
A thin film transistor with low off-state current is provided. A gate electrode, a gate insulating film provided to cover the gate electrode, a microcrystalline semiconductor layer provided on the gate insulating film, and an amorphous semiconductor layer provided on the microcrystalline semiconductor layer, A source region and a drain region which are provided on the amorphous semiconductor layer and whose side surfaces are substantially flush with the side surface of the amorphous semiconductor layer; and a source electrode provided in contact with the source region and the drain region And the drain electrode, and the amorphous semiconductor layer overlapping the source region and the drain region is thicker than the amorphous semiconductor layer overlapping the channel formation region, and the side surfaces of the source region and the drain region are amorphous. The side surface of the semiconductor layer forms a taper shape with the outermost surface of the amorphous semiconductor layer, and the taper angle of the side surface alleviates the concentration of the electric field in the vicinity of the junction between the source region and the drain region and the amorphous semiconductor layer. To do It provides the angle of the thin film transistor to allow. [Selection] Figure 1 |