Patent ID: 8586475

Claim:
A method of manufacturing a semiconductor device including a first region of a semiconductor substrate and a second region of the semiconductor substrate, comprising: (a) forming a first gate insulating film of a first NMOS transistor over the first region; (b) forming a second gate insulating film of a second NMOS transistor over the second region; (c) after the steps (a) and (b), forming a first gate electrode of the first NMOS transistor over the first gate insulating film; (d) after the steps (a) and (b), forming a second gate electrode of the second NMOS transistor over the second gate insulating film; (e) after the steps (c) and (d), implanting ions into the first and second gate electrodes in order to be amorphous, respectively; (f) after the step (e), forming an insulating film in order to cover the first and second gate electrodes; (g) after the step (f), removing the insulating film formed over the second gate electrode in order to keep the insulating film formed over the first gate electrode; (h) after the step (g), performing thermal processing in order to crystallize the first and second gate electrodes; and (i) after the step (h), removing the insulating film formed over the first gate electrode, wherein, after the step (i), a tensile stress is applied in a first channel region of the first NMOS transistor under the first gate electrode, and wherein a drain current of the first NMOS transistor is increased by the tensile stress.