Patent ID: 8294157

Claim:
A semiconductor device comprising: a first semiconductor film and a second semiconductor film, over a substrate; and a gate electrode formed over the first semiconductor film and the second semiconductor film with a gate insulating film interposed between the gate electrode and the first semiconductor film and second semiconductor film, wherein the first semiconductor film includes: a first channel forming region provided in a region which overlaps with the gate electrode with the gate insulating film interposed therebetween; a first impurity region forming a source region or drain region, provided so as to be adjacent to the first channel forming region; and a second impurity region provided so as to be adjacent to the first channel forming region and the first impurity region, wherein the second semiconductor film includes: a second channel forming region provided in a region which overlaps with the gate electrode with the gate insulating film interposed therebetween; a third impurity region forming a source region or drain region; and a fourth impurity region provided so as to be adjacent to a region between the second channel forming region and the third impurity region, wherein conductivity of the first impurity region is different from that of the second impurity region, the third impurity region, and the fourth impurity region, and wherein the second impurity region and the fourth impurity region have an impurity element at substantially same concentration.