Reactivity of organosilicon precursors in remote hydrogen microwave plasma chemical vapor deposition of silicon carbide and silicon carbonitride thin-film coatings

A number of organosilicon precursors for silicon carbide and silicon carbonitride thin-film coatings, such as silanes, carbosilanes, aminosilanes, and disilazane, respectively, were characterized in terms of their reactivity in a remote microwave plasma chemical vapor deposition process, which was induced using hydrogen as plasma generating gas. The process displayed high selectivity with respect to the activating species and the chemical bonds in the molecular structure of the precursors. In view of very short life times of excited hydrogen plasma species the activation step takes place with an exclusive contribution of ground-state hydrogen atoms. The C-H, C-C, Si-C, Si-N, C-N and N-H bonds present in the molecules of the precursors are non-reactive and only the Si-H or Si-Si bonds play a key role in the activation step. The reactivity of the precursors was characterized in a quantitative way by the yield of the film growth parameter. The yield parameter expressing the mass of film per unit mass of the precursor fed to the reactor was calculated from the slopes of linear plots of time dependencies of film mass and precursor mass, which were determined for each investigated precursor. The reactivity of the precursors was found to be strongly dependent on the number of the Si-H units present in their molecules and those containing two Si-H units appeared to be most reactive. Copyright (C) 2009 John Wiley & Sons, Ltd.