Stacked oxide material, semiconductor device, and method for manufacturing the semiconductor device

A semiconductor device comprising:

• a gate electrode;
• a gate insulating film over the gate electrode;
• a first oxide semiconductor layer over the gate insulating film;
• a second oxide semiconductor layer over the first oxide semiconductor layer;
• a third oxide semiconductor layer over the second oxide semiconductor layer;
• and
• a source electrode and a drain electrode electrically connected to the second oxide semiconductor layer,
• wherein each of the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer contains indium, gallium and zinc,
• wherein the second oxide semiconductor layer comprises a channel formation region which overlaps with the gate electrode with the first oxide semiconductor layer and the gate insulating film interposed therebetween, and
• wherein the second oxide semiconductor layer comprises crystals which are c-axis-aligned.

A semiconductor device comprising:

• a gate electrode;
• a gate insulating film;
• a first oxide semiconductor layer;
• a second oxide semiconductor layer;
• a third oxide semiconductor layer;
• and
• a source electrode and a drain electrode electrically connected to the second oxide semiconductor layer,
• wherein each of the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer contains indium, gallium and zinc,
• wherein the second oxide semiconductor layer is between the first oxide semiconductor layer and the third oxide semiconductor layer,
• wherein the second oxide semiconductor layer comprises a channel formation region,
• wherein the gate electrode and the channel formation region overlap with each other with the first oxide semiconductor layer and the gate insulating film interposed therebetween, and
• wherein the second oxide semiconductor layer comprises crystals which are c-axis-aligned.