Semiconductor device, display device, and method for producing semiconductor device

A method of manufacturing a semiconductor device, comprising:

• preparing a substrate;
• and
• forming a thin film transistor on the substrate, said thin film transistor including a semiconductor layer, a gate electrode, a source electrode, a drain electrode, and a gate-insulating layer,
• wherein the step of forming the thin film transistor includes forming the source electrode and the drain electrode which each include a main layer including aluminum or copper an upper layer above the main layer, having a first layer including a refractory metal, and a lower layer underneath the main layer, having a second layer including a refractory metal, and
• wherein, in the step of forming the source electrode and the drain electrode, the upper layer is formed so as to cover a top of the main layer and, among side faces of the main layer, at least a side face that is located at a position corresponding to the semiconductor layer, and the upper layer is in contact with the semiconductor layer.