Patent ID: 8786793

Claim:
A method for manufacturing a display device, comprising the steps of: forming a gate electrode over a substrate; forming a first insulating film over the gate electrode; forming a first semiconductor film over the first insulating film; adding a first impurity into the first semiconductor film, the first impurity imparting a first conductivity type or a second conductivity type; irradiating the first semiconductor film with laser light at a region in which the first semiconductor film and the gate electrode are overlapped, after adding the first impurity into the first semiconductor film; forming a buffer layer over the first semiconductor film after irradiating the first semiconductor film with laser light; forming a second semiconductor film over the buffer layer, the second semiconductor film including a second impurity which imparts the first conductivity type; etching the first semiconductor film, the buffer layer, and the second semiconductor film; forming a conductive film over the second semiconductor film so that the conductive film is in contact with the first insulating film and side surfaces of the first semiconductor film, the buffer layer, and the second semiconductor film; and etching the conductive film to form a source electrode and a drain electrode over the second semiconductor film, wherein the first semiconductor film is a microcrystalline semiconductor film, and wherein the buffer layer is an amorphous semiconductor film.