One kind or plural kinds of elements selected from a groups III, IV or V elements are introduced in an amorphous silicon film, and then crystallized by heating at 600 DEG C. or less. The crystallization develops from a region where the element has been introduced in a direction parallel to a substrate. An active region of a semiconductor device is formed in a portion of the crystallized semiconductor layer in such a manner that the relation between the crystal growth direction and the direction in which the electric current of the device is selected in accordance with a desired mobility of the active region.