Patent ID: 6906383

Claim:
An active matrix type liquid crystal display comprising at least an N-channel thin film transistor and a P-channel thin film transistor formed on an insulating surface, wherein said N-channel thin film transistor comprising: a first gate electrode, a first semiconductor film, a gate insulating film between the first gate electrode and the first semiconductor film, said first semiconductor film comprising a first impurity region, a first channel region and a second impurity region contiguous to the first impurity region, said second impurity region having a first region overlapped with the first gate electrode and a second region not overlapped with the first gate electrode, wherein an N-type impurity concentration of said second impurity region is lower than that of the first impurity region, said P-channel thin film transistor comprising: a second gate electrode, a second semiconductor film, the gate insulating film between the second gate electrode and the second semiconductor film, said second semiconductor film comprising a second channel region, and a third impurity region not overlapped with said second gate electrode, wherein each of the first channel region and the second channel region has a first length at a surface being in contact with the gate insulating film and a second length at a surface being in contact with the insulating surface, wherein the first length is shorter than the second length, and wherein said second impurity region has a first length at a surface being in contact with said gate insulating film and a second length at a surface being in contact with said insulating surface, said first length longer than said second length.