Patent ID: 7977168

Claim:
A method for manufacturing a semiconductor device comprising: forming a first semiconductor film over a substrate; wherein the first semiconductor film comprises an oxide semiconductor, irradiating the first semiconductor film with a laser beam through a photomask including a shield for shielding the laser beam to form an island-shaped semiconductor film in such a way that a first region in the first semiconductor film which has been irradiated with the laser beam through a region in which the shield in the photomask is not formed is sublimed, and a second region which is not irradiated with the laser beam in the first semiconductor film remains without being sublimed by using a region in which the shield in the photomask is formed as a mask; forming a source electrode and a drain electrode over the island-shaped semiconductor film; forming a gate insulating film over the island-shaped semiconductor film, the source electrode and the drain electrode; and forming a gate electrode over the gate insulating film, wherein the source electrode and the drain electrode are formed in such a way that a shield for shielding the laser beam over a light-transmitting substrate is used as a photomask, a second semiconductor film formed as a first layer and a metal film formed as a second layer which are formed over a light-transmitting substrate are used as a source substrate, and the metal film is formed over the island-shaped semiconductor film by subliming the second semiconductor film in such a way that the source substrate is irradiated with the laser beam through the photomask.