Method of manufacturing ZnO-based thin film transistor

A method of manufacturing a ZnO-based thin film transistor (TFT, the method comprising:

• forming a ZnO-based channel layer on a gate insulating layer;
• forming a conductive material layer on the gate insulating layer and the ZnO-based channel layer;
• forming a mask layer on the conductive material layer having a pattern corresponding to source and drain electrodes on both sides of the ZnO-based channel layer;
• forming the source and drain electrodes by etching the conductive material layer not covered by the mask layer using a wet etchant having a higher selectivity with respect to the conductive material layer than the ZnO-based channel layer;
• and
• forming a passivation layer covering the source and drain electrodes and the ZnO-based channel layer,
• wherein the source and drain electrodes are formed by a first etching to remove a portion of the conductive material layer not covered by the mask layer, and a second etching to completely remove the portion of the conductive material layer not covered by the mask layer and over-etch the surface of the ZnO-based channel layer, so that the ZnO-based channel layer includes an over-etched portion between the source electrode and the drain electrode.