SiH4 surface reactions

Nienhuis [189] has used a fitting procedure for the seven most sensitive elementary parameters (reactions SiH4 -t- SiH2 and Si2H6 -I- SiHi, dissociation branching ratio of SiH4, surface reaction coefficient and sticking probability of SiHa, and diffusion coefficients of SiH and H). In order to reduce the discrep-... 

Ultrahigh-vacuum (UHV) surface spectroscopy has been used with molecular beams of SiH4 and mass spectroscopy to elucidate the Si growth mechanism (67, 143). Joyce et al. (67) found that Si growth is preceded by an induction period when surface oxide was removed as SiO. The subsequent film growth proceeds by growth and coalescence of adjacent nuclei with no apparent formation of defects. Henderson and Helm (144) proposed a step-flow model in which adatoms from SiH4 surface reactions difluse to kink sites. 

Silicon cluster reactions are an example of a newly emerging field of research which is very amenable to study with electronic structure methods. This exercise will examine the potential surface for silicon cation reacting with silane (SiH4). Such reactions are central to the growth of large silicon clusters, which occurs by sequential additions of -SiHj ... 

In silicon based MEMS processing, common CVD films include polysilicon, silicon oxide, and silicon nitride. For polysilicon films (usually the structural layer), an LPCVD pyrolysis method is generally used with silane (SiH4) as the source gas [see Eq. (1)]. To obtain a imiform film across the wafer, the process is carried out at low pressure to ensure that the deposition is surface reaction controlled and not diffusion limited. Typical process temperatures are in the range of 580-650°C, and pressures between 0.1 and 0.4Torr. 

Similarly, [SiH4] generates thin alloy and intermetaUic compound phases by reaction with clean Ta, Mo, W, Rh, Ni, Pt, Cu and Au surfaces at elevated temperatures [130]. 

For a disk temperature of 800 K, calculate the Si growth rate as a function of disk rotation rate, over the range 500 to 1300 rpm. At 500 rpm and at 1300 rpm, what fraction of the Si growth is attributable to the reaction of SiH4 itself with the surface (i.e.,reaction 1 in silicon, surf) ... 

The initial pyrolysis reaction of SiH4 has been explored extensively (98), and the growing consensus is that the thermal decomposition of SiH4 involves the elimination of H2 to form silylene, as shown in equation 1 (98, 101). Possibly, thermal pyrolysis is controlled by heterogeneous reactions on hot surfaces (102, 103), but this hypothesis is controversial, and considerable experimental evidence for a gas decomposition mechanism exists (98). However, at low pressures and high temperatures, heterogeneous decomposition will likely be important in the overall mechanism (104). 

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