Patent ID: 7745824

Claim:
A semiconductor device comprising: a first n-channel type TFT provided in a pixel; a second n-channel type TFT provided in a driving circuit; and a third n-channel type TFT provided in said driving circuit, wherein the gate electrode of said first n-channel type TFT has a laminate structure comprising a first conductive layer and a second conductive layer provided over the first conductive layer, wherein the first conductive layer of the gate electrode of said first n-channel type TFT has a substantially rectangular cross-sectional shape, wherein the first conductive layer of the gate electrode of said first n-channel type TFT has a same width as a width of a bottom of the second conductive layer of the gate electrode of said first n-channel type TFT, wherein and the gate electrode of each of said second and third n-channel type TFTs has a laminate structure comprising a first conductive layer having a first width as a lower layer and a second conductive layer having a second width smaller than the first width as an upper layer, and wherein a source wire connected with said first n-channel type TFT is provided across a pixel portion comprising said pixel and comprises at least one material selected from the group consisting of Cu and Ag.