JPS6481211A - Formation of semiconductor thin film - Google Patents

Abstract

PURPOSE:To form a silicon thin film good in its crystallinity by a simple method, by sequentially depositing a polycrystalline semiconductor layer as a lower layer and an amorphous semiconductor layer as an upper layer respectively on an insulated substrate and thereafter by performing heat treatment. CONSTITUTION:A CVD method of 650 deg.C or more in a growth temperature is used to deposit a polycrystalline Si layer 1-2 on an insulated substrate 1-1. Since the layer on this state is very small in its grain diameter and so irregular in its crystal orientation resulting in a variety in orientations, only the growth temperature is lowered to be 650 deg.C or below without interrupting the formation of the film. Thereupon an amorphous Si layer 1-4 is serially deposited on said polycrystalline Si layer 1-2, so that the polycrystalline Si layer as a lower layer and the amorphous Si layer as an upper layer are formed by one step of the CVD method. Next crystal growth of the amorphous Si layer 1-4 is performed by heat treatment to form an Si layer 1-5 good in its crystallinity. Since crystal growth of the amorphous Si layer begins with the polycrystalline Si layer serving as a seed crystal and the heat treatment is performed for long hours, only the crystal grains with a single crystalline bearing grow much and so a polycrystalline Si film large in its grain diameter can be obtained uniform in its orientation and good in its crystallinity.