Effect of Higher-Order Silane Deposition on Spatial Profile of Si-H₂/Si-H Bond Density Ratio of a-Si:H Films

Abstract

We studied how the deposition of SiH₃ radicals, higher-order silane molecules, and clusters contributed to the bond configuration of hydrogenated amorphous silicon (a-Si:H) films. In our experiment, the deposition of three species was controlled using a multi-hollow discharge plasma chemical vapor deposition (MHDPCVD) method using a cluster-eliminating filter. We reduced the incorporation of higher-order silane (HOS) molecules into the films by increasing the gas flow velocity in the hollows from 1008 to 2646 cm/s. The results show that the lower incorporation of HOS molecules into the films reduced the SiH₂/SiH bond ratio, i.e., I_SiH2/I_SiH. Moreover,two-dimensional profiles of the I_SiH2/I_SiH ratio and the surface morphology suggest that the surface migration of HOS molecules is similar to that of the SiH₃ radicals, and the I_SiH2/I_SiH ratio is localized by the deposition of HOS molecules. Moreover, the results of optical emission spectroscopy show that HOS radical generation is irrelevant to the gas flow velocity.