Method for making polycrystalline silicon thin film

Abstract

A method for making a polycrystalline silicon thin film by crystallizing an amorphous silicon thin film at a low temperature of 500.degree. C. to 600.degree. C. Over a glass substrate is deposited a microcrystalline silicon seed layer having a thickness of 100 .ANG. to 500 .ANG., using the chemical vapor deposition method. Over the microcrystalline silicon seed layer, a hydrogen-containing amorphous silicon layer is formed by chemical vapor deposition, at a temperature of 180.degree. C. to 270.degree. C., which is then crystallized to form a polycrystalline silicon thin film. A hydrogen-containing amorphous silicon layer having a thickness of 300 .ANG. to 500 .ANG. may be formed over the glass substrate. In this case, the hydrogen-containing amorphous silicon layer is crystallized at a temperature of 600.degree. C., to form a polycrystaline seed layer. Over the polycrystalline silicon seed layer, another hydrogen-containing amorphous silicon layer is formed which is then crystallized by a heat treatment, to form a polycrystalline thin film. The heat treatment is carried out at a temperature of 580.degree. C. to 600.degree. C. for a period of 20 hours to 50 hours.

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