Semiconductor device

A semiconductor device comprising:

• a pixel portion including a first transistor and a light-emitting element;
• and
• a driver circuit comprising a second transistor,
• wherein each of the first transistor and the second transistor comprises:
• a first gate electrode over a substrate;
• a first oxide film over the substrate;
• an oxide semiconductor film over the first oxide film, wherein the oxide semiconductor film and the first gate electrode overlap with each other;
• a source electrode and a drain electrode over the first oxide film;
• and
• second oxide film over the oxide semiconductor film, the second oxide film having an island-shaped,
• wherein a bottom surface of the oxide semiconductor film of the first transistor is in contact with a top surface and a side surface of each of the source electrode and the drain electrode of the first transistor,
• wherein a bottom surface of the oxide semiconductor film of the second transistor is in contact with a top surface and a side surface of each of the source electrode and the drain electrode of the second transistor,
• wherein the second transistor further comprises a second gate electrode overlapping with the second oxide film and the first gate electrode of the second transistor,
• wherein the second gate electrode of the second transistor has the same potential as the first gate electrode of the second transistor, and
• wherein one of the source electrode and the drain electrode of the first transistor is electrically connected to a pixel electrode of the light-emitting element.