Determination of the Rate Constants for Bimolecular Reactions of O(3P) Atom with SiH4and SiHCl3

Abstract

The reaction of silanes with oxygen atom is very important because of the roles in semiconductor fabrication such as chemical vapor deposition (CVD) processes, as well as in the study of unstable nature under oxygen atmosphere including combustion and explosion processes. However, experimental kinetic data for the reaction of oxygen atom with silanes are not well documented and are very limited, compare to the data for the reaction with olefins. The O(P) atom reactions with SiHCl3 and SiH4 were theoretically studied by Q. Zhang et al. They calculated the rate constants with the Arrhenius expression over a wide temperature range of 200-3000 K, specifically on the hydrogen abstraction channel, optimizing geometrical parameters of reactants at saddle point by ab initio method. Buchta et al. reported the experimental work on the reaction of O(P) with silanes by discharge flow method and mass spectrometry. The rate constant for the reaction of O(P) with SiHCl3 was given as a function of temperature, k = (1.41 ± 0.28) × 10−11 cm3molcule−1s−1 exp[−(13.5 ± 2.7) kJmol−1/RT] in the range of 298-773 K, however, the rate expression considered only hydrogen abstraction channel rather than total reaction pathways. In this note, we report kinetic data on the measurements of total reaction pathways for reaction of O(P) with SiHCl3 and SiH4, by using discharge flow/chemiluminescence imaging technique. The rate constants were obtained to be (1.38 ± 0.06) × 10−13 cm3molecule−1s−1 for SiH4 and (1.74 ± 0.13) × 10−13 cm3molecule−1s−1 for SiHCl3 at 298 K. The NO2 chemiluminescence was observed and analyzed utilizing second order rate equations, which provides apparently much information at an initial reaction zone.