Thin-film transistor, method of manufacturing the same, liquid crystal display panel having the same and electro-luminescence display panel having the same

A method of manufacturing a thin-film transistor comprising:

• forming a gate electrode on a base substrate;
• forming a gate insulation layer on the substrate to cover the gate electrode;
• forming an active layer on the gate insulation layer to cover the gate electrode;
• forming a buffer layer on the active layer to suppress an oxidation of the active layer;
• primarily etching first predefined portions of the buffer layer and the active layer;
• forming a source electrode and a drain electrode on the primarily etched active layer, wherein the source electrode and the drain electrode are separated from each other by a predetermined distance;
• and
• secondarily etching second predefined portions of the buffer layer and the active layer, using as an etching mask at least one of the source electrode and the drain electrode.