Method for manufacturing semiconductor device

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

• forming a gate electrode over a substrate;
• forming a gate insulating layer over the gate electrode;
• forming an oxide semiconductor layer over the gate insulating layer in a film formation chamber into which a substance containing a halogen element is introduced in a gaseous state;
• and
• forming a source electrode and a drain electrode over the oxide semiconductor layer.

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

• forming a source electrode and a drain electrode over a substrate;
• forming an oxide semiconductor layer over the source electrode and the drain electrode in a film formation chamber into which a substance containing a halogen element is introduced in a gaseous state;
• forming a gate insulating layer over the oxide semiconductor layer;
• and
• forming a gate electrode over the gate insulating layer.