Surface chemistry of alkylsilanes on Si(100)2 × 1

Abstract

The adsorption and thermal decomposition of ethylsilane, diethylsilane, triethylsilane, tetraethylsilane, dimethylsilane and di-isobutylsilane were studied on the Si(100)2 × 1 reconstructed surface using temperature-programmed desorption mass spectrometry and high-resolution electron energy-loss spectroscopy. Ethylsilane, diethylsilane and di-isobutylsilane each adsorbs dissociatively onto the surface up to a saturation coverage of approximately 0.25 ML. Thermal decomposition proceeds via β-hydride elimination. Ethylene and hydrogen desorption occurs at 700 and 800 K, respectively, for ethylsilane and diethylsilane. Isobutylene desorption is observed at 635 K, followed by hydrogen desorption at 800 K for di-isobutylsilane. Dimethylsilane adsorbs dissociatively up to a saturation coverage of 0.25 ML. Thermal decomposition proceeds via dehydrogenation of the methyl groups. Hydrogen desorption is observed at 800 K for low coverages with a 5–10 K peak shift to higher temperatures for higher coverages. Triethylsilane adsorbs dissociatively, but saturation coverage could not be established in these experiments. Thermal decomposition proceeds via β-hydride elimination, resulting in the desorption of ethylene at 700 K and hydrogen at 800 K. Adsorption of tetraethylsilane is not observed. For every precursor, except tetraethylsilane, hydrogen adsorbs exclusively as the (2 × 1) monohydride. No adsorption of any of these precursors on the native SiO 2 surface is observed at 100 K.