Optimization of the High Rate Microcrystalline Silicon Deposition Conditions of the Multi-Hole-Cathode Very High Frequency SiH4/H2 Plasma

The multi-hole-cathode very high frequency (MHC-VHF) plasma deposition technique is a new promising approach to achieve ultra high deposition rates, without the need to use extreme small electrode gaps at higher pressures. The microcrystalline silicon (muc-Si:H) high rate deposition conditions of the MHC-VHF plasma technique have been optimized using the micro-structural information of material, with 9.1% conversion efficiency when integrated in a pin-device, deposited at 2.3 nms^-1 by the high pressure depletion (HPD)-VHF plasma technique. The absence of the narrow high stretching modes (NHSM) at 2083 cm^-1 and 2101 cm^-1 in the IR spectrum together with the high film crystallinity (X_c~0.55-0.70), is proposed as a simple tool to qualify the optimum micro-structural (muc-Si:H properties at high deposition rate conditions. The NHSM corresponds to the presence of mono- and dihydrides on crystalline oriented grain boundaries in less dense material, which oxidize in several days to weeks. Using the proposed optimization strategy we achieved to obtain dense muc-Si:H films at a deposition rate of 2.1 nms^-1 using MHC-VHF with the same micro-structural properties as the optimum HPD-VHF plasma deposition condition