Patent ID: 7256457

Claim:
A thin-film transistor device comprising: a first thin-film transistor of n-type of electric conduction having a first channel region, a first low-concentration impurity region and a first gate electrode covering nearly the whole first low-concentration impurity region and the first channel region; a second thin-film transistor of n-type of electric conduction having a second channel region, a second low-concentration impurity region and a second gate electrode covering part of the second low-concentration impurity region and the second channel region; and a third thin-film transistor of p-type of electric conduction having a third channel region and a third gate electrode covering the third channel region, wherein: the impurities are contained at different concentrations in the first and second channel regions and in the third channel region; and the first and second gate electrodes have a different layer structure or are formed from different materials than the third gate electrode.