| CPC H01L 29/7869 (2013.01) [H01L 27/1225 (2013.01); H01L 27/124 (2013.01); H01L 27/1255 (2013.01); H01L 29/78648 (2013.01); H01L 29/78696 (2013.01)] | 4 Claims |
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1. A method for manufacturing a semiconductor device comprising:
forming a first gate electrode;
forming a gate insulating film over the first gate electrode;
forming an oxide semiconductor film over the gate insulating film;
forming a first insulating film over the oxide semiconductor film;
forming a first oxide film over the first insulating film by a sputtering method using an In—Ga—Zn metal oxide target in an atmosphere containing oxygen gas;
forming an island-shaped second oxide film by processing the first oxide film; and
performing a heat treatment at a temperature higher than or equal to 150° C. and lower than or equal to 350° C. after forming the island-shaped second oxide film,
wherein, in the process of forming the first oxide film, a proportion of the oxygen gas in a deposition gas is higher than or equal to 10% and lower than or equal to 100%,
wherein the island-shaped second oxide film overlaps with the first gate electrode with the oxide semiconductor film interposed therebetween, and
wherein a proportion of indium in the island-shaped second oxide film is higher than a proportion of indium in the oxide semiconductor film.
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