Patent ID: 7714387

Claim:
A semiconductor device with a thin-film transistor (TFT), comprising: a substrate; an island-shaped semiconductor film formed directly on the substrate or over the substrate with an intervening backing film, the semiconductor film serving as an active layer of a first TFT; a pair of source/drain regions of the first TFT, formed in the semiconductor film; a channel region of the first TFT, formed between the pair of sourer/drain regions in the semiconductor film; and alignment marks provided substantially proximate but separate from the first TFT, wherein the alignment marks are provided on both sides of the source/drain regions, wherein the pair of source/drain regions are smaller in thickness than a remainder of the semiconductor film, wherein the alignment marks are equal in thickness to the remainder of the semiconductor film, and wherein a thickness difference between the pair of source/drain regions and the remainder of the semiconductor film is set in a range from at least ten angstroms (10 −9 m) to one hundred angstroms (10 −8 m).