Influence of hydrogen, ion distribution and silyl radical surface diffusion length on silicon thin film growth under high pressure and high power in VHF-PECVD

摘要

Microcrystalline silicon thin films were prepared by VHF-PECVD and studied by several diagnostic techniques. Deposition rate and Raman crystallinity were mapped out on the pressure-power density plane. A model was constructed based on the one-electron impact model to obtain the densities of different silicon related radicals, and densities of hydrogen in the plasma and a quantitative kinetic surface reaction model was constructed to obtain silyl diffusion length on the surface. Microcrystalline silicon growth was understood by a competing dominance between hydrogen etching, SiH2 generation, ion distribution and SiH3 diffusion length on the surface. These results contribute to understand microcrystalline silicon growth process, which is very important in fabricating microcrystalline silicon materials and solar cells.