Active matrix substrate, method of manufacturing active matrix substrate, and display device

A method of manufacturing an active matrix substrate, the method comprising:

• forming a thin film transistor on a substrate, the thin film transistor including an oxide semiconductor layer, a gate electrode, and source and drain electrodes, the oxide semiconductor layer including a first region as a channel region, the gate electrode being disposed in confronted relation with the first region of the oxide semiconductor layer with a first insulating film in between, and the source and drain electrodes being electrically coupled to the oxide semiconductor layer;
• forming, in a different region from the thin film transistor, an electrode layer that is level with the gate electrode and includes a first end;
• and
• forming a second insulating film between the substrate and the electrode layer, the second insulating film including a second end at a more retreated position than the first end of the electrode layer,
• the oxide semiconductor layer further including a second region having lower resistance than the first region, and
• the electrode layer being electrically coupled, at the first end, to the second region of the oxide semiconductor layer.

A display device provided with an active matrix substrate, the active matrix substrate comprising:

• a substrate;
• a thin film transistor that is provided on the substrate and includes an oxide semiconductor layer, a gate electrode, and source and drain electrodes, the oxide semiconductor layer including a first region as a channel region, the gate electrode being disposed in confronted relation with the first region of the oxide semiconductor layer with a first insulating film in between, and the source and drain electrodes being electrically coupled to the oxide semiconductor layer;
• an electrode layer that is level with the gate electrode, is provided in a different region from the thin film transistor, and includes a first end;
• and
• a second insulating film that is provided between the substrate and the electrode layer and includes a second end at a more retreated position than the first end of the electrode layer,
• the oxide semiconductor layer further including a second region having lower resistance than the first region, and
• the electrode layer being electrically coupled, at the first end, to the second region of the oxide semiconductor layer.