Abstract: In a liquid crystal display (LCD) device having a thin film transistor (TFT), the TFT includes a source electrode, a drain electrode and a semiconductor layer. At least one of the source electrode and drain electrode includes a first layer including copper and a second layer forming an oxide layer and covering the first layer. The semiconductor layer has a substantially linear current-voltage relationship with said source electrode or drain electrode including said first and second layers, when a voltage is applied between the semiconductor layer and said source electrode or drain electrode.

Abstract: In a liquid crystal display (LCD) device having a thin film transistor (TFT), the TFT includes a source electrode, a drain electrode and a semiconductor layer. At least one of the source electrode and drain electrode includes a first layer including copper and a second layer forming an oxide layer and covering the first layer. The semiconductor layer has a substantially linear current-voltage relationship with said source electrode or drain electrode including said first and second layers, when a voltage is applied between the semiconductor layer and said source electrode or drain electrode.

Abstract: The present invention includes a liquid crystal display device with an oxide film having high adhesiveness to a semiconductor layer or a pixel electrode to thereby prevent oxidation of a wiring material or the like, and includes a source electrode and a drain electrode having high conductivity, and a manufacturing method therefor. In one embodiment of the present invention, a liquid crystal display device has a TFT electrode of a TFT substrate, wherein a source electrode or a drain electrode includes a layer of mainly copper and an oxide covering an outer part of the layer. Further, in the present invention, the semiconductor layer or the pixel electrode and said source electrode or the drain electrode are in ohmic contact in the TFT electrode.

Abstract: A method of forming an oxide film on a surface of a copper alloy, including the steps of providing a copper alloy including copper and an element selected from the group consisting of Mn, Zn, Ga, Li, Ge, Sr, Ag, Ba, Pr and Nd, and diffusing atoms of the element to a surface of the copper alloy so as to form an oxide film on the surface of the copper alloy, wherein a concentration of the element in the copper alloy is more than 0.1 and not more than 20 atomic percentage and within a solubility limit of the element in the copper.