Logic circuit and semiconductor device

A semiconductor device comprising:

• a pixel portion having a first transistor and a light-emitting element electrically connected to the first transistor;
• and
• a drive circuit electrically connected to the pixel portion and having a second transistor,
• the first transistor comprises:
• a first insulating layer;
• a first source electrode layer and a first drain electrode layer over the first insulating layer;
• a first oxide semiconductor layer having regions in contact with top surfaces and side surfaces of the first source electrode layer and the first drain electrode layer;
• and
• a first gate electrode layer over the first oxide semiconductor layer with a first gate insulating layer interposed therebetween,
• the second transistor comprises:
• a second gate electrode layer;
• the first insulating layer over the second gate electrode layer;
• a second source electrode layer and a second drain electrode layer over the first insulating layer;
• a second oxide semiconductor layer having regions in contact with top surfaces and side surfaces of the second source electrode layer and the second drain electrode layer;
• and
• a third gate electrode layer over the second oxide semiconductor layer with a second gate insulating layer interposed therebetween,
• wherein the first oxide semiconductor layer and the second oxide semiconductor layer each comprise indium, gallium, and zinc.