THE ADSORPTION OF HYDROGEN-CHLORIDE ON POLYCRYSTALLINE BETA-SILICON CARBIDE

The reactivity of HCl, a by-product of SiC chemical vapor deposition ( CVD) from chlorine-containing precursors, is of particular interest be cause it has been reported that addition of HCl inhibits the SiC CVD p rocess. In this study, HCl adsorption on polycrystalline beta-SiC was examined with Auger electron spectroscopy and temperature-programmed d esorption (TPD). HCl adsorbs readily on SiC at 300 K with an initial s ticking probability of 0.11 and forms a strong bond with an activation energy for desorption of 64 kcal/mol. The only product detected by TP D is HCl, which desorbs in a peak centered at 1010 K. No silicon- or c arbon-containing desorption products are found, demonstrating that HCl does not etch the SiC surface under these conditions. HCl inhibition of SiC CVD can be accounted for qualitatively with a surface site-bloc king mechanism.