Patent ID: 7087962

Claim:
An active matrix display device including a thin film transistor for switching a pixel of said display device, said active matrix display device comprising: a substrate having an insulating surface; a semiconductor layer formed on said insulating surface; an insulating film including a gate insulator therein formed on said semiconductor layer, said insulating film having a thicker portion located on and completely covering a channel region of said semiconductor layer, and thinner portions located on source and drain regions of said semiconductor layer, wherein said source and drain regions extend throughout the thickness of the semiconductor layer, a gate electrode formed on the thicker portion; an interlayer insulating film formed on said insulating film and said gate electrode; and at least one electrode formed over said interlayer insulating film for contacting at least one of said source and drain regions, wherein first and second LDD regions are formed in said semiconductor layer between the channel region and the source region and between the channel region and the drain region below extending parts of the thicker portion, said extending parts of the thicker portion extending beyond the edges of the gate electrode, wherein a concentration of an impurity contained in said source and drain regions monotonically decreases in a thickness direction of the semiconductor layer at least partly toward said insulating surface, wherein said extending parts of the thicker portion and said thinner portions have first surfaces being in contact with said semiconductor layer and second surfaces being in contact with said interlayer insulating film, wherein said at least one electrode extends through said interlayer insulating film and said thinner portion of said insulating film.