Patent ID: 7990508

Claim:
A method of manufacturing a liquid crystal display device comprising: forming a gate wiring over an insulating surface by using a first mask; forming a common electrode over the insulating surface; forming a first insulating film over the gate wiring; forming a first amorphous semiconductor film over the first insulating film; forming a second amorphous semiconductor film containing an impurity element which imparts n-type conductivity, over the first amorphous semiconductor film; forming a conductive film over the second amorphous semiconductor film; patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film together by using a second mask; removing a portion of the first amorphous semiconductor film, a portion of the second amorphous semiconductor film and a portion of the conductive film to form a source region, a drain region and a source wiring after patterning the first amorphous semiconductor film, the second amorphous semiconductor film and the conductive film; forming a transparent electrode electrically connected to the conductive film, and in contact with the first insulating film; forming a second insulating film formed over the transparent electrode, and in contact with the first amorphous semiconductor film, the second amorphous semiconductor film, the source wiring, and the transparent electrode; and forming an alignment film over the transparent electrode and the common electrode; wherein the portion of the second amorphous semiconductor film is between the source region and the drain region, and wherein the transparent electrode and the common electrode are disposed so that liquid crystal molecules are controlled by an electric field produced between the transparent electrode and the common electrode, wherein the gate wiring is separated from the common electrode, and wherein the transparent electrode and the common electrode are overlapped with each other.