Patent ID: 8859330

Claim:
A method for manufacturing a semiconductor device, comprising the steps of: forming an oxide semiconductor film; forming a void into the oxide semiconductor film by an implantation step for implanting a noble gas ion inside the oxide semiconductor film; exposing the oxide semiconductor film after the implantation step; and performing a heating step under reduced pressure, in a nitrogen atmosphere, or in a noble gas atmosphere on the exposed oxide semiconductor film, so that hydrogen or water contained in the oxide semiconductor film is released through the void, wherein a peak of a concentration of an implanted noble gas element in the oxide semiconductor film is greater than or equal to 1×10 19 atoms/cm 3 and less than or equal to 3×10 22 atoms/cm 3 in the implantation step, wherein an ion implantation method, an ion doping method, or a plasma immersion ion implantation method is used for the implantation step, and wherein the oxide semiconductor film to which the noble gas ion is implanted is a channel formation region of a transistor.