Method of manufacturing semiconductor device

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

• forming an oxide semiconductor layer over a substrate;
• placing the substrate in a treatment chamber;
• supplying a gas to the treatment chamber;
• and
• treating the oxide semiconductor layer by supplying microwaves to the gas in the treatment chamber to reduce a concentration of hydrogen in the oxide semiconductor layer,
• wherein the gas is made into plasma by the microwaves.

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

• forming an oxide semiconductor layer over a substrate;
• forming a source electrode layer and a drain electrode layer, wherein a portion of the oxide semiconductor layer is exposed between the source electrode layer and the drain electrode layer;
• and
• irradiating the oxide semiconductor layer with microwaves to reduce a concentration of hydrogen in the oxide semiconductor layer after forming the source electrode layer and the drain electrode layer.