Method for processing oxide semiconductor film and method for manufacturing semiconductor device

A semiconductor device comprising:

• an oxide semiconductor layer over an insulating surface, the oxide semiconductor layer comprising:
• a source region including a first region;
• a drain region including a second region;
• and
• a channel region including a third region;
• a first insulating layer over the oxide semiconductor layer;
• a gate electrode over the insulating layer;
• and
• a second insulating layer over the gate electrode,
• wherein the source region and the drain region contains an impurity,
• wherein the source region and the drain region are formed in a self-aligned manner with respect to the gate electrode,
• wherein the first region and the second region includes a metal element,
• wherein the metal element is not a main component of the second insulating layer,
• wherein a concentration of oxygen in the first region is lower than a concentration of oxygen in the third region, and
• wherein a concentration of oxygen in the second region is lower than the concentration of oxygen in the third region.

A semiconductor device comprising:

• an oxide semiconductor layer over an insulating surface, the oxide semiconductor layer comprising:
• a source region including a first region;
• a drain region including a second region;
• and
• a channel region including a third region;
• a first insulating layer over the oxide semiconductor layer;
• a gate electrode over the insulating layer;
• and
• a second insulating layer over the gate electrode,
• wherein the source region and the drain region contains an impurity,
• wherein the source region and the drain region are formed in a self-aligned manner with respect to the gate electrode,
• wherein the first region and the second region includes a material having a reducing property,
• wherein the material is not a main component of the second insulating layer,
• wherein a concentration of oxygen in the first region is lower than a concentration of oxygen in the third region, and
• wherein a concentration of oxygen in the second region is lower than the concentration of oxygen in the third region.

A semiconductor device comprising:

• an oxide semiconductor layer over an insulating surface, the oxide semiconductor layer comprising:
• a source region including a first region;
• a drain region including a second region;
• and
• a channel region including a third region;
• a first insulating layer over the oxide semiconductor layer;
• a gate electrode over the insulating layer;
• a sidewall insulating layer over the insulating layer;
• and
• a second insulating layer over the gate electrode;
• wherein the source region and the drain region contains an impurity,
• wherein the source region is formed in a self-aligned manner with respect to the gate electrode and the sidewall insulating layer,
• wherein the first region and the second region includes a metal element,
• wherein the metal element is not a main component of the second insulating layer,
• wherein a concentration of oxygen in the first region is lower than a concentration of oxygen in the third region, and
• wherein a concentration of oxygen in the second region is lower than the concentration of oxygen in the third region.