The patent relates to a thin-film transistor to reduce a leakage current between source/drain of a thin-film transistor. Etch the silicon by means of a liquid or a non-ionized gas, to form an island-shaped silicon semiconductor regionhaving a tapered edge.Alternatively, the island-shaped silicon semiconductor region having the tapered edge is formed by means of a dry etching process, a part damaged by plasma is removed through etching of the edge part by means of the above-mentioned liquid or gas.A leakage current between source/drain caused by a part can be reduced. Failures such as disconnection occurring when a gate electrode crosses the island-shaped silicon region can also be reduced. |