Thin film transistor substrate having source and drain upper-layer electrodes

A thin film transistor substrate including a thin film transistor having a layered structure in which a first conductive layer, a first insulation layer, a second insulation layer made of an oxide insulator different from a material of the first insulation layer, an oxide semiconductor layer, a second conductive layer, a third conductive layer made of an oxide, and a third insulation layer made of an oxide are disposed on a substrate, the thin film transistor substrate comprising:

• a gate electrode provided on the substrate and having a side surface, the gate electrode being included in the first conductive layer;
• an opening insulation film covering the substrate and in contact with the side surface of the gate electrode, the opening insulation film being provided with a first opening portion having a side surface on the gate electrode, the opening insulation film being included in the first insulation layer;
• a gate insulation film provided on the gate electrode and the opening insulation film, the gate insulation film being included in the second insulation layer;
• a semiconductor channel film provided on the gate insulation film and encompassed by the first opening portion of the opening insulation film as seen in plan view, the semiconductor channel film being included in the oxide semiconductor layer;
• a source electrode and a drain electrode provided on the semiconductor channel film and included in the second conductive layer;
• a source upper-layer electrode provided at least on an upper surface of the source electrode and included in the third conductive layer;
• a drain upper-layer electrode provided at least on an upper surface of the drain electrode and included in the third conductive layer;
• and
• an interlayer insulation film having a portion provided on the source upper-layer electrode and the drain upper-layer electrode and in contact with the semiconductor channel film, the interlayer insulation film being included in the third insulation layer.