Silicon carbide vapor-phase reactions

A review article on the CVD processes used to form SiC and Si3N4 by one of the pioneers in this area, Erich Fitzer [Fitzer, E., and D. Hegen, Chemical vapor deposition of silicon carbide and silicon nitride—Chemistry s contribution to modem silicon ceramics, Angew. Chem. Int. Ed. Engl, 18, 295 (1979)], describes the reaction kinetics of the gas-phase formation of these two technical ceramics in various reactor arrangements (hot wall, cold... 

Numerous ceramics are deposited via chemical vapor deposition. Oxide, carbide, nitride, and boride films can all be produced from gas phase precursors. This section gives details on the production-scale reactions for materials that are widely produced. In addition, a survey of the latest research including novel precursors and chemical reactions is provided. The discussion begins with the mature technologies of silicon dioxide, aluminum oxide, and silicon nitride CVD. Then the focus turns to the deposition of thin films having characteristics that are attractive for future applications in microelectronics, micromachinery, and hard coatings for tools and parts. These materials include aluminum nitride, boron nitride, titanium nitride, titanium dioxide, silicon carbide, and mixed-metal oxides such as those of the perovskite structure and those used as high To superconductors. 

Deng J, Su K, Wang X, Zeng Q, Cheng L, Xu Y et al (2009) Thermodynamies of the gas-phase reactions in chemical vapor deposition of silicon carbide with methyltrichlorosilane precursor. Theoret Chem Acc 122 1-22... 

Silicon carbide whiskers, usually produced from silica and carbon, are widely used for ceramic matrix composites [38]. Tbe vapor-liquid-solid (VLS) process is accepted as the mechanism for SiC whisker production (Fig. 15.1.4). This process requires formation of a liquid phase of a transition metal at the reaction sites. Elemental sources of Si and C are usually supplied in vapor phase form as SiO and CH4, respectively [39]. The vapors are deposited on the surface of the liquid metal and dissolved into the liquid metal droplets. Since the whiskers are precipitated from the dissolved components, metal droplets are often observed at the tip of the whiskers [39]. 

The other method of developing fine, spherical particles is through the use of plasma techniques which may involve a phjrsical phenomenon or a chemical reaction [105]. In the former case, a simple spherodizing process takes place when irregular shaped powder is introduced into the plasma which melts it and then vaporizes it to form uniform spheres. When a chemical reaction is involved, the reactants in the solid or gaseous form in contact with the plasma are allowed to react in the vapor phase and the products are allowed to condense as deposits of tine powder on the cooler regions of tire chamber after leaving the plasma. Colloidal spheres of alumimun, copper, aluminum nitride and silicon carbide are made in this way. 

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