Patent ID: 7557412

Claim:
A semiconductor device comprising: a substrate; and a first region comprising a first circuit comprising a first TFT and a second region comprising a second circuit comprising a second TFT and a third circuit comprising a third TFT over the substrate, wherein the first TFT comprises a first crystalline semiconductor film as a first active layer, wherein the second TFT comprises a second crystalline semiconductor film as a second active layer, wherein the third TFT comprises a third crystalline semiconductor film as a third active layer, wherein a size of a crystal grain of the first crystalline semiconductor film and a size of crystal grain of the second crystalline semiconductor film are smaller than in a size of a crystal grain of the third crystalline semiconductor film, and wherein a fluctuation of sizes of crystal grains of the first crystalline semiconductor film and a fluctuation of size of crystal grain of the second crystalline semiconductor film are smaller than a fluctuation of sizes of crystal grains of the third crystalline semiconductor film.