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Laser-Induced-Fluorescence Study of the SiH 2 Density in RF SiH 4 Plasmas with Xe, Ar, He, and H 2 Dilution Gases

1995; Institute of Physics; Volume: 34; Issue: 1R Linguagem: Inglês

10.1143/jjap.34.307

1347-4065

Akihiro Kono, Naoki Koike, Hideshi Nomura, Toshio Goto,

Diamond and Carbon-based Materials Research

The silylene ( SiH 2 ) density in a parallel-plate RF (13.56 MHz) discharge using monosilane ( SiH 4 ) gas has been measured by using laser-induced fluorescence spectroscopy. The effect of Xe, Ar, He and H 2 dilution gases on the SiH 2 density was investigated at a total gas pressure of 40 mTorr. In all dilution cases, the SiH 2 density was relatively insensitive to the SiH 4 fraction ( x ) in the mixtures for x \gtrsim0.5; however, except in the case of H 2 dilution, marked increase of the SiH 2 density was observed with decreasing x for x \lesssim0.5. The production and loss mechanisms for SiH 2 are discussed on the basis of the observed SiH 2 density and supplementary optical emission measurements. The results indicate that, in highly diluted ( x \lesssim0.1)SiH 4 /Xe and SiH 4 /Ar mixtures, the production of SiH 2 via energy transfer from excited Xe and Ar atoms to SiH 4 is dominant over direct electron impact dissociation of SiH 4 .