Abstract: A method for crystallizing an amorphous silicon thin-film is provided, in which amorphous silicon thin-films on a large-area glass substrate for use in a TFT-LCD (TFT-Liquid Crystal Display) are crystallized uniformly and quickly by a scanning method using a linear lamp to prevent deforming of the glass substrate. The crystallization method includes the steps of forming an amorphous silicon thin-film on a glass substrate, and illuminating a linear light beam on the amorphous silicon thin-film from the upper portion of the glass substrate according to a scanning method. The crystallization method is applied to a polycrystalline silicon thin-film transistor manufacturing method including the steps of forming an amorphous silicon thin-film on a glass substrate, and crystallizing the amorphous silicon of the thin-film transistor according to a scanning method using a linear light beam.