Silicon film growth species

The flux summary within the boxes in Fig. 17.2 shows the mass flux (g/cm2-s) of both the silane and silylene to the surface, resulting in deposition of silicon and release of volatile hydrogen. At low temperature, the film growth is primarily from silane, although it is quite low. By Ts = 925 K, there is sufficient silane decomposition that the surface fluxes of the two species are becoming comparable. At Ts = 1300 K, the silylene flux is dominant, carrying most of the silicon to the surface. 

The most conventional non-equilibrium plasma-chemical systems that produce diamond films use H2-CH4 mixture as a feed gas. Plasma activation of this mixture leads to the gas-phase formation of hydrogen atoms, methyl radicals (CH3), and acetylene (C2H2), which play a major role in further film growth. Transport of the gas-phase active species to the substrate is mostly provided by diffusion. The substrate is usually made from metal, silicon, or ceramics and is specially treated to create diamond nucleation centers. The temperature of the substrate is sustained at the level of 1000-1300 K to provide effective diamond synthesis. The synthesis of diamond films is provided by numerous elementary surface reactions. Four chemical reactions in particular describe the most general kinetic features of the process. First of all, surface recombination of atomic lydrogen from the gas phase into molecular hydrogen returns back to the gas phase ... 

The deposition of Si02 by several CVD processes and surface reactions of gaseous reactants with a Si02 surface has been monitored in situ by ATR and the standard FTIR transmission methods [53,119-121]. Using these methods, information about the IR absorption of the surface species, the film, and the ambient gas in the reactor during the film growth can be obtained. It is well known that CVD parameters such as the quality of the film, the rate of deposition, and the profile of chemical composition are sensitive to the transport and reactions of species in the plasma as well as to the surface reactions. The IR absorption of CVD silicon dioxide after deposition (ex situ) was considered in Section 5.2. 

Silicon oxide species are also detected in IR spectra after aging PS films in ambient air [233, 240, 252, 253]. However, the native oxide growth on PS can be suppressed by treating the surface in a HF solution [253], The aging of PS layers can also lead to the appearance of absorption bands (2850-3000 cm ) associated with hydrocarbon contamination [237]. Aged samples exhibit a broad IR absorption band in the 3000-3600-cm region due to adsorption of water molecules, giving SiOH complexes [240]. 

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