Method for manufacturing semiconductor device

A method for manufacturing a semiconductor device, the method comprising the steps of:

• forming a first insulating film over a substrate;
• forming a source electrode and a drain electrode over the first insulating film;
• forming an oxide semiconductor film over the source electrode and the drain electrode;
• adding oxygen to the oxide semiconductor film;
• forming a second insulating film over the oxide semiconductor film added with oxygen;
• and
• forming a gate electrode over the second insulating film,
• wherein the oxide semiconductor film is formed by sputtering at a temperature equal to or higher than 100° C. and equal to or lower than 400° C.

A method for manufacturing a semiconductor device, the method comprising the steps of:

• forming a first insulating film over a substrate;
• forming an oxide semiconductor film over the first insulating film;
• forming a source electrode and a drain electrode over the oxide semiconductor film;
• adding oxygen to the oxide semiconductor film;
• forming a second insulating film over the oxide semiconductor film added with oxygen;
• and
• forming a gate electrode over the second insulating film,
• wherein the oxide semiconductor film is formed by sputtering at a temperature equal to or higher than 100° C. and equal to or lower than 400° C.