The reaction of ground state oxygen atom with silane, SiH 4 + O( 3 P), has been studied for the past three decades because of its important role in semiconductor fabrication processes. The reaction is essential for understanding the process in chemical vapor deposition (CVD) using oxygen and silane to form SiO 2 layers. The film thickness in deposition of SiO 2 in a SiH 4 /O 2 -inductive coupled plasma (ICP) system is controlled by the gas flow rate. The relationship between oxygen atom density, which contributes directly to the deposition of SiO 2 , and the gas flow rate was reported by Tong. Moreover, recently enormous amounts of silane have been consumed by semiconductor-related industries for solar cells, glass fiber coating, and bio-inert layers on titanium implants. The discharge of silane into the atmosphere is one of the main safety problems that needs to be solved by the semiconductor industry.2 During industrial processes, a large amount of silane is released into the atmosphere and it is explosive in air at a concentration of only about 1%. Silane is a pyrophoric and highly flammable gas, and a mixture of silane and air produces a spontaneous combustion reaction at room temperature without a source of ignition. Babushok et al. studied self-ignition and flame propagation of silane by computer simulation using kinetic and thermodynamic data; 3 however, the kinetic behavior of silane with oxygen atoms is not understood clearly, and the kinetic data are widely dispersed depending on the experimental techniques. 9a,b They suggested that the oxygen atom reaction was the important process in the oxidation of SiH 4 and that additional experimental data would be necessary for a precise description of the dynamics of silanebased mixtures.In our laboratory, the reaction SiH 4 + O( 3 P) was studied and the rate constant was determined to be k = (1.38 AE 0.06) × 10 −13 cm 3 /molecule/s at 298 K. 10a A temperature dependence study over a temperature range of 313-356 K indicated the possibility of negative apparent activation energy; however, the temperature range was too narrow to obtain reliable Arrhenius parameters.
Results and DiscussionThe triplet state oxygen atoms, O( 3 P), are consumed by the following processes:The consumption rate of O( 3 P) iswhere k wall is for the reaction by the wall or other third body molecules. The reaction rates were determined near the starting point of the reaction and the reactions were carried out under pseudofirst order conditions for oxygen atom.
