Kinetic model for the chemical vapor deposition of tungsten in the silane reduction process

Abstract

The kinetics involved in the chemical vapor disposition of tungsten, using the silane reduction chemistry, is modeled by a triple Eley–Rideal mechanism, which includes three competitive surface reaction pathways: (1) silane reduction of surface adsorbed WF6, (2) surface dissociation of silane and silicon reduction of WF6, and (3) (residual) hydrogen reduction of surface adsorbed WF6. The last two reaction pathways have not been properly considered in the past, and will be shown to be of critical importance to the understanding the complex Arrhenius behavior exhibited by the silane reduction process. A quantitative deposition rate expression, with no fitting parameters, is derived from the kinetic model using kinetic constants in the literature. The model can predict the deposition rate obtained experimentally, after taking into account the effect of reactant depletion in the reactor.