Semiconductor device

A display device comprising:

• a substrate;
• and
• a pixel formed on the substrate, wherein
• the pixel includes an organic EL element, a driving thin film transistor connected to the organic EL element, and a switching thin film transistor connected to a first gate electrode of the driving thin film transistor,
• the switching thin film transistor includes an oxide semiconductor layer, a drain electrode in contact with the oxide semiconductor, a source electrode in contact with the oxide semiconductor, a gate insulating film on the oxide semiconductor layer, and a second gate electrode on the gate insulating film,
• a channel is formed in the oxide semiconductor layer between the drain electrode and the source electrode,
• the gate insulating film is arranged to cover the oxide semiconductor,
• a channel length direction is defined by a direction of the drain electrode and the source electrode opposed to each other,
• a channel width direction is defined by an orthogonal direction to the channel length direction,
• the oxide semiconductor layer is formed in a rectangular shape having a first side that is arranged along the channel length direction, a second side opposed to the first side, a third side connecting the first side and the second side and arranged along the channel width direction, and a fourth side opposed to the third side, in a plan view,
• a width of the oxide semiconductor layer in the channel width direction is wider than a width of the gate electrode in the channel width direction, and
• the first side and two corners of the oxide semiconductor layer of the rectangular shape overlap with the source electrode, and the second side and another two corners of the oxide semiconductor of the rectangular shape overlap with the drain electrode, in a plan view.