Patent ID: 8841663

Claim:
An oxide semiconductor thin-film transistor (TFT), comprising: a gate electrode disposed on a substrate; a source electrode and a drain electrode both comprising a first metal element with a first oxide formation free energy; a gate insulation layer insulating the gate electrode from the source electrode and the drain electrode; and an oxide semiconductor pattern comprising: a first surface contacting the gate insulation layer; and a second surface contacting the source electrode and the drain electrode, the second surface opposing the first surface, wherein the oxide semiconductor pattern entirely comprises an oxide material comprising an ion of at least one of indium (In), gallium (Ga), zinc (Zn), and tin (Sn), and further comprises an added element other than indium (In), gallium (Ga), zinc (Zn), and tin (Sn), with a second oxide formation free energy, the absolute value of the second oxide formation free energy being greater than or equal to the absolute value of the first oxide formation free energy, and wherein, in the oxide semiconductor pattern, an amount of the added element in a portion proximate to the first surface is zero or smaller than an amount of the added element in a portion proximate to the second surface.