Patent ID: 7759681

Claim:
A semiconductor device comprising a differential amplifier circuit comprising: an insulating substrate; a first thin film transistor comprising: a first active layer over the insulating substrate, having: a first source region; a first drain region; and a first channel forming region between the first source region and the first drain region; and a first gate electrode adjacent to the first active layer; a second thin film transistor comprising: a second active layer over the insulating substrate, having: a second source region; a second drain region; and a second channel forming region between the second source region and the second drain region; and a second gate electrode adjacent to the second active layer; a first input terminal electrically connected to the first gate electrode; a second input terminal electrically connected to the second gate electrode; and an element-added region comprising an element, wherein each of the first active layer and the second active layer is formed of a semiconductor film, wherein the element accelerates the crystallizing of the semiconductor film, wherein a first distance between the first active layer and the element-added region is substantially equal to a second distance between the second active layer and the element-added region, and wherein the element-added region is separated from the first active layer by the first distance and from the second active layer by the substantially equal second distance.