Chlorine incorporation in silicon films deposited by low-pressure rf discharges in gas mixtures of SiCl4+H2+Ar

Abstract

Silicon films were deposited from tetrachlorosilane by its dissociation in argon and hydrogen rf plasma at a pressure of 2 Torr. The concentration of chlorine incorporated in the films was found to be dependent on the macrovariables of the plasma such as power input and substrate position in the plasma reactor. Mass spectrometric measurements of the plasma showed that the concentration of HCl in the plasma was strongly dependent on the power input and on position in the plasma along the gas stream. At high input powers the HCl formed in the plasma dissociates to free radicals, contributing to a recombination process in the gas phase and codeposition with silicon on the substrate. The correlation between the HCl reactions in the plasma and the incorporation of Cl in the deposit is shown.