Patent ID: 7791075

Claim:
A display device comprising: a gate electrode; a gate insulating film over the gate electrode; a microcrystalline semiconductor film over the gate insulating film, comprising a channel formation region; a channel protective layer over and in contact with the channel formation region; a source region over the channel protective layer and over and in contact with the microcrystalline semiconductor film; a drain region over the channel protective layer and over and in contact with the microcrystalline semiconductor film; a source electrode over the source region; and a drain electrode over the drain region, wherein the channel formation region comprises a doped region to which an impurity element is doped, wherein the impurity element imparts either p-type conductivity or n-type conductivity to the microcrystalline semiconductor film, wherein the doped region does not overlap with the source electrode, and wherein the doped region does not overlap with the drain electrode.