ADSORPTION AND DECOMPOSITION OF DIETHYLGERMANE ON POROUS SILICON SURFACES

Diethylgermane [(CH3CH2)2GeH2], (DEG), is a potential molecular precur sor for germanium deposition on silicon surfaces. In this study, Fouri er transform infrared (FTIR) transmission spectroscopy was employed to examine the adsorption and decomposition of DEG on high surface area porous silicon surfaces. The FTIR spectra revealed that DEG dissociati vely adsorbs on porous silicon surfaces at 200 K to form SiH, GeH and SiCH2CH3 surface species. No spectral features were observed for GeCH2 CH3 surface species. The C-H stretching modes between 2959 and 2882 cm -1, the Si-H stretch at 2082 cm-1 and the Ge-H stretch at 1999 cm-1 we re then employed to monitor the decomposition of the surface species d uring thermal annealing, Between 300 and 640 K the GeH species transfe rred hydrogen to the silicon surface and formed SiH species. The SiCH2 CH3 species decomposed to yield gas phase CH2=CH2 and additional SiH s urface species between 400 and 700 K. These reaction products were con sistent with a beta-hydride elimination mechanism, i.e. SiCH2CH3 --> S iH + CH2=CH2. From 660-800 K the SiH surface species decreased concurr ently with H-2 desorption. The decomposition pathways of the surface s pecies following DEG adsorption indicate that DEG may be useful for ge rmanium deposition on silicon surfaces.