Patent ID: 7531839
Filing Date: 2009-05-12
Classification: G02F,H01L

Abstract:
1. A display device, comprising: a pixel portion and a gate driver circuit that are formed on an insulating surface, wherein said pixel portion comprises a first thin film transistor of one conductivity type, wherein said gate driver circuit comprises a decoder including a plurality of NAND circuits each comprising a plurality of second thin film transistors of said one conductivity type, wherein two of said plurality of second thin film transistors of said one conductivity type are connected in series, wherein other two of said plurality of second thin film transistors are connected to each other in parallel, and wherein each of said first thin film transistor and said plurality of second thin film transistors comprises: a semiconductor island over a substrate, said semiconductor island comprising a source region, a drain region, and a channel region located between said source region and said drain region; an insulating film over said semiconductor island; a first conductive film provided over said insulating film; and a second conductive film over said first conductive film, wherein an edge of said first conductive film extends beyond an edge of said second conductive film, wherein said insulating film has a first portion which is covered with said first conductive film and a second portion which is not covered with said first conductive film, and wherein a thickness of said second portion is thinner than a thickness of said first portion.