Ab initio chemical kinetics of Isobutene + SiH3 reaction

Abstract

The detailed kinetic mechanism between isobutene and SiH₃ radicals was investigated theoretically using the composite electronic structure method CBS-QB3 in conjugated with the Rice-Ramsperger-Kassel-Marcus-based master equation (RRKM-ME) rate modeling. The study reveals that the title reaction proceeds through two primary pathways: (i) addition of SiH₃ to the double bond and (ii) H-abstraction by SiH₃, leading to various products. The addition pathway forms two primary products, P3 and P4. The H-abstraction pathway results in two product channels, P1 + SiH₄ and P2 + SiH₄. Among these, the adduct P3 is identified as the most thermodynamically and kinetically favorable intermediate at T < 900 K. However, at T > 900 K, P1 and P4 gain prominence. The calculated geometrical parameters, thermodynamic properties, and kinetic data align with existing/related literature for selected species. These findings provide further mechanistic insights as well as reliable information for detailed kinetic modeling of silicon chemical vapor deposition (CVD) processes, which are of significant technological importance.