In-situ mass spectroscopy of ECR silane plasmas for amorphous and microcrystalline silicon growth

摘要

ECR silane plasmas for the deposition of a-Si:H andμc-Si films were investigated by in-situ mass spectroscopy (MS) using a quadrupole residual gas analyzer. The results showed that the intensities of ionic and neutral species (H, H{sub}2, He, Ar, Si and SiH{sub}x) in the 2 % SiH{sub}4/He plasma are strongly dependent on the deposition conditions such as chamber pressure, input power and hydrogen dilution. In all cases, the prevalence of Si ions was observed over SiH, SiH{sub}2 and SiH{sub}3 ions, suggesting a high decomposition rate of the silane in the plasma. In particular, the population of atomic hydrogen in the plasma seems to play a key role in the properties of both a-Si:H andμc-Si films. For example, the increased intensity of atomic hydrogen, compared to that of molecular hydrogen, resulted in the better quality a-Si:H film, showing a higher photo and dark conductivity ratio of ～10{sup}5. The intensity of the hydrogen species was especially sensitive to the chamber pressure. The correlation between MS spectra and film properties is presented.