Patent ID: 8101444

Claim:
A method for manufacturing a semiconductor device, comprising the steps of: forming a gate electrode over a substrate; forming a gate insulating layer over the gate electrode; forming a first semiconductor layer over the gate insulating layer, wherein the first semiconductor layer includes a microcrystalline semiconductor comprising an acceptor impurity element; forming a second semiconductor layer over the first semiconductor layer, wherein the second semiconductor layer includes an amorphous semiconductor; forming an n-type or p-type semiconductor layer over the second semiconductor layer; forming a conductive layer over the n-type or p-type semiconductor layer; performing a first etching of the conductive layer so that a pair of conductive layers are formed; performing a second etching of the n-type or p-type semiconductor layer; and performing a third etching of the pair of conductive layers after the step of performing the second etching, wherein the first semiconductor layer is formed by a plasma-enhanced chemical vapor deposition method using a process gas comprising at least a dopant gas comprising the acceptor impurity element, wherein the process gas is supplied with high-frequency electric power having frequencies more than or equal to 3 MHz from two or more power supply units to generate plasma, and wherein the frequencies include at least a first frequency and a second frequency which are different from each other.