Display device, a thin film transistor used in a display device, and a manufacturing method of a thin film transistor

A display device comprising a thin film transistor for controlling light emission of the display element and the display element, a thin film transistor includes a gate electrode formed on a supporting substrate of insulating, it is formed on the substrate to cover the gate electrode a gate insulating film, a channel layer formed on the gate insulating film, a channel protection layer formed on the upper surface of the channel layer, a pair of contact layers being connected to be formed on the upper surface of the channel protective layer and the channel layer When, a source electrode and a drain electrode connected to the pair of contact layers, the pair of the contact layer has a surface which is in contact at the side surface of the channel layer.