Laser-induced explosive decomposition of Fluoromethylsilanes - reductive chemistry for gas-phase deposition of Carbon, Silicon Carbide and Si/C/F material
✍ Scribed by J. Pola; J. Tláskal; Z. Bastl; H. Bürger; P. Moritz
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 58 KB
- Volume
- 54
- Category
- Article
- ISSN
- 0022-1139
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✦ Synopsis
Polyfluoromethylsilanes
constituted of fluorocarbon and silane moieties are expected to be susceptible to heterogeneously assisted thermal decomposition in the gas-phase that occurs both with fluorocarbons [l] and silane 121. A truly homogeneous decomposition mechanism may be induced by tuning IR laser radiation into C-F and/or Si-H vibrational modes [3]. We report that decomposition of (CF3)2SiH2 (I), CF3SiH3(II), HCF2SiH3 (III) and H2CFSiH3 (IV) can be induced at I-50 Torr as an explosive reaction initiated by irradiation with a single pulse from a TEA CO2 laser. The reaction threshold depends on the pressure of the particular fluoromethylsilane and on the wavenumber and delivered fluence of the laser radiation. While gaseous silicon-containing products (SiF4 and SiHF3) are the same in all decomposition processes, the carbon-containing products differ. Thus, solid C, Si/C/F(H) and SIC materials are formed (and deposited from the gas phase on a cold surface) from I, II and IV, respectively, whereas CH4 is formed from III. The different products can be accounted for by reductive processes involving transfer of fluorine from C to Si and hydrogen from Si to C, the chemistry being specific for each fluoromethylsilane. Possible mechanisms will be inferred from the products arising from the non-explosive decomposition induced by a great number of low-fluence pulses. Analyses of solid deposits by IR spectroscopy, ESCA and SEM techniques will be used to comment on their electrical conductivity and to assess their potential in microelectronics.