Hydrogen Elimination Kinetics during Chemical Vapor Deposition of Silica Films

Abstract

Hydrogen elimination mechanisms involved in the low-pressure chemical vapor deposition of silica films from SiH4/O2/N2 mixtures are investigated. The main purpose of this work is to elucidate the mechanisms that limit hydrogen elimination in the silica deposition process under the mass-transport and gas-phase kinetic regimes. To this end, different gas-phase, surface, and mass-diffusion processes relevant to the SiH4 oxidation and silica growth chemistry are considered and discussed on the basis of the influence of temperature, total gas flow rate and O2-to-SiH4 flow ratio on deposition rate and hydrogen content in the film, as determined by infrared spectroscopy and elastic recoil detection analysis. Our results indicate a clear relationship between the growth and hydrogen elimination kinetics, and support a hydrogen elimination model based on radical-surface interactions.

Modeling heterogeneity and memory effects on the kinetic roughening of silica films grown by chemical vapor deposition

“…Once deposited, these species would lead to renewed active sites, such as ϵSiH, and would be eventually converted into passive sites through different dehydrogenation/passivation mechanisms. 28 Summarizing our experimental data, it seems that our system could be described as a heterogeneous surface, being composed by two types of sites, active and passive, with 12 Thus, a complete theoretical model should incorporate these facts, as well as the memory effects mentioned above, in order to account not only for the different surface scaling behaviors obtained at the two temperature values considered, but also for the different film roughnesses obtained.…”

Influence of Hydrogen Incorporation on the Structure and Stoichiometry of Chemically Vapor Deposited Silica Films

“…The overstoichiometric character of our films is accentuated as the [O 2 ]: [SiH 4 ] decreases, because of the increasing concentration of OH groups. In O 2 -rich mixtures the dehydrogenation reactions are enhanced, 64 which results in a lower OH concentration and thus in an O/Si ratio closer to 2.…”