Thin film transistor and liquid crystal display unit

摘要

A bottom-gate type thin-film transistor free from alignment shift of the gate electrode and from damage caused by injection of impurities. The crystal grains of a polycrystalline silicon thin-film are anisotropically grown to form a prescribed angle relative to the gate length direction. The angle between the gate length direction and the longitudinal direction of the grains is adjusted according to use of the liquid crystal display unit. The bottom-gate transistor includes an undercoat insulating layer containing impurities on the substrate. Impurities are diffused from the undercoat layer to the semiconductor layer by laser-annealing the amorphous silicon.