Effects of RF Power and Working Pressure on the Properties of Nc-Si:H Thin Films Deposited by an ICP-CVD System

Abstract

An ICP-CVD system attached with four internal antennas was used to deposit Si thin films. Hydrogenated nanocrystalline silicon (nc-Si:H) films were prepared as functions of RF power and working pressure, while the flow ratio of SiH 4 /H 2 was fixed at 1/5. During deposition, an OES (optical emission spectrometer) and a plasma probe were used to characterize the conditions of plasma. The crystalllinity, structure, and Si-H bonding of these Si:H films were investigated using Raman scattering spectroscopy, XRD, and FTIR. It is found that the crystallinity of nc-Si:H film was significantly affected by electron density which was increased with the increase of the power and the decrease of pressure. The deposition rate increases with the increase of RF power as well as working pressure. This could be due to high electron density (when the working pressure was fixed) or less hydrogen etching (when the RF power was fixed).