A numerical model was developed to predict gas-phase nucleation of particles during silane pyrolysis. The model includes a detailed clustering mechanism for the formation of hydrogenated silicon clusters containing up to ten silicon atoms. This mechanism was coupled to an aerosol dynamics moment model to predict particle growth, coagulation, and transport. Both zero-dimensional transient simulations, at 1-2 atm pressure, and one-dimensional steady-state stagnation-point flow simulations, at 1-2 Torr pressure, were conducted. The effects of carrier gas, temperature, pressure, silane concentration, and flow rate were examined. The results predict that hydrogen as carrier gas, compared to helium, suppresses nucleation, and that particle formation for the case of hydrogen carrier gas increases strongly with increasing initial silane-to-hydrogen ratio. For the conditions examined, predicted particle nucleation rates increase dramatically with increasing temperature. The effect of total pressure depends on the pressure regime: at 1-2 atm pressure particle formation is predicted to be insensitive to pressure, whereas at 1-2 Torr particle formation is predicted to increase strongly with increasing pressure. The predicted effects on particle formation of temperature, pressure, carrier gas, and silane concentration are all qualitatively consistent with published experimental results. In the stagnation-point flow simulations the flow rate is found to affect particle dynamics because of the opposed effects of convective transport toward the heated water and thermophoretic transport away from the wafer.

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Articles you may be interested inComplete thermodynamically consistent kinetic model of particle nucleation and growth: Numerical study of the applicability of the classical theory of homogeneous nucleation Process sensing and metrology in gate oxide growth by rapid thermal chemical vapor deposition from SiH 4 and N 2 O Characterization of fluorinated tetra ethyl ortho silicate oxide films deposited in a low pressure plasma enhanced chemical vapor deposition reactor A detailed chemical kinetic model is presented for silicon oxide clustering that leads to particle nucleation during low-pressure silane oxidation. Quantum Rice-Ramsperger-Kassel theory was applied to an existing high-pressure silane oxidation mechanism to obtain estimates for the pressure dependence of rate parameters. Four classes of clustering pathways were considered based on current knowledge of reaction kinetics and cluster properties in the Si-H-O system. The species conservation equations and a moment-type aerosol dynamics model were formulated for a batch reactor undergoing homogeneous nucleation and particle growth by surface reactions and coagulation. The chemical kinetics model was coupled to the aerosol dynamics model, and time-dependent zero-dimensional simulations were conducted. The effects of pressure and temperature were examined, and the main contributing processes to particle formation and growth were assessed, for conditions around 0.8 Torr, 773 K, and an initial oxygen-to-silane ratio of 15.

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A detailed chemical kinetics mechanism was developed to model silicon oxide clustering during high density plasma chemical vapor deposition of SiO 2 films from silane-oxygen-argon mixtures. An inductively coupled plasma reactor was modeled in a one-dimensional multicomponent two-temperature framework. Spatial distributions of species concentrations were calculated. The effects of discharge parameters and the main processes contributing to cluster formation were examined. A sensitivity analysis was conducted to determine the dominant reactions that affect the model results.