Thin-film transistor, method of manufacturing the same, and method of manufacturing backplane for flat panel display

A method of manufacturing a backplane for a flat panel display (FPD), the method comprising:

• forming a gate electrode on a substrate;
• forming a first insulating layer on the substrate to cover the gate electrode;
• performing a plasma treatment on an upper surface of the first insulating layer, the plasma treatment using a halogen gas;
• forming an oxide semiconductor layer on the first insulating layer and positioned to correspond to the gate electrode;
• forming source and drain electrodes on the first insulating layer and over portions of the oxide semiconductor layer;
• forming a second insulating layer on the first insulating layer to cover the oxide semiconductor layer and the source and drain electrodes, the second insulating layer comprising a first hole exposing one of the source and drain electrodes;
• and
• forming a pixel electrode on the second insulating layer and within the first hole;
• wherein the forming a first insulating layer comprises forming the first insulating layer by a sol-gel process using a solution comprising hafnium chloride (HfCl4) dissolved in a solvent that includes at least one of acetonitrile and ethylene glycol.