SURFACE-CHEMISTRY OF ALKYLSILANES ON SI(100)2X1

The adsorption and thermal decomposition of ethylsilane, diethylsilane , triethylsilane, tetraethylsilane, dimethylsilane and di-isobutylsila ne were studied on the Si(100)2 x 1 reconstructed surface using temper ature-programmed desorption mass spectrometry and high-resolution elec tron energy-loss spectroscopy. Ethylsilane, diethylsilane and di-isobu tylsilane each adsorbs dissociatively onto the surface up to a saturat ion coverage of approximately 0.25 ML. Thermal decomposition proceeds via beta-hydride elimination. Ethylene and hydrogen desorption occurs at 700 and 800 K, respectively, for ethylsilane and diethylsilane. Iso butylene desorption is observed at 635 K, followed by hydrogen desorpt ion at 800 K for di-isobutylsilane. Dimethylsilane adsorbs dissociativ ely up to a saturation coverage of 0.25 ML. Thermal decomposition proc eeds 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 dissociativ ely, but saturation coverage could not be established in these experim ents. Thermal decomposition proceeds via P-hydride elimination, result ing in the desorption of ethylene at 700 K and hydrogen at 800 K. Adso rption of tetraethylsilane is not observed. For every precursor, excep t tetraethylsilane, hydrogen adsorbs exclusively as the (2 x 1) monohy dride. No adsorption of any of these precursors on the native SiO2 sur face is observed at 100 K. (C) 1997 Elsevier Science B.V.