PREPARATION OF POLYCRYSTALLINE SILICON THIN-FILMS BY CATHODE-TYPE RF GLOW-DISCHARGE METHOD

Polycrystalline silicon films were deposited by the cathode-type rf glow discharge method where a protective mesh against ions was attached to the cathode using 0.5% SiH4 diluted with hydrogen at a pressure of 0.09 Torr. The deposited films were found to be polycrystalline for a wide range of applied rf power (0.05-1 W cm-2) and substrate temperature above 200-degrees-C. The crystallization mechanism was suggested to be the surface reaction in the chemical equilibrium state between growth and etching of weak Si-SiH(x) bonds on the growing surface caused by hydrogen radicals in the plasma. Electrical and optical properties of the film suggested that substrate temperatures above 350-degrees-C and deposition power densities above 0.5 W cm-2 are suitable for formation of polycrystalline silicon.