Patent ID: 7537972
Filing Date: 2009-05-26
Classification: G02F,H01L

Abstract:
1. A method of manufacturing a semiconductor device comprising: forming a first semiconductor layer and a second semiconductor layer on an insulating surface; forming a first insulating film over the first semiconductor layer and the second semiconductor layer; forming a first conductive layer over the first insulating film, a second conductive layer over the first conductive layer, a third conductive layer having a tapered portion over the first insulating film, and a fourth conductive layer having a tapered portion over the third conductive layer; doping the first semiconductor layer with an impurity element by using the second conductive layer as a mask; removing the tapered portion of the third conductive layer; doping the second semiconductor layer with an impurity element by using the third conductive layer as a mask; and wherein a first taper angle formed by a bottom surface and a side surface of the third conductive layer is larger than a second taper angle formed by a bottom surface and a side surface of the fourth conductive layer.