Patent ID: 7749820

Claim:
A manufacturing method of a thin film transistor using a single photomask, the method comprising the steps of: sequentially forming a first insulating film, a first conductive film, a second insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film; forming a first resist mask over the second conductive film using the single photomask, wherein the first resist mask has a recessed portion and a projected portion; performing first etching, using the first resist mask, to etch the first conductive film, the second insulating film, the semiconductor film, the impurity semiconductor film, and the second conductive film; performing second etching in which the first conductive film is selectively side-etched to allow a width of the first conductive film to be narrower than a width of the first resist mask; forming a second resist mask from the first resist mask after performing the second etching, the second resist mask having an opening over the second conductive film; and performing third etching using the second resist mask, wherein, underneath the opening, the third etching is performed to allow the second conductive film, the impurity semiconductor film, and a part of the semiconductor film to be removed, and wherein, underneath the projected portion, the third etching is performed to allow the second conductive film, the impurity semiconductor film, and the semiconductor film to be left.