Desorption product yields following Cl 2 adsorption on Si(111) 7 × 7: coverage and temperature dependence

Abstract

Abstract : Chlorine plays an essential role during the plasma etching of silicon surfaces. The interaction between chlorine and silicon is also important in the epitaxial growth of silicon during chemical vapor deposition with SiCl4 + H2 or SiCl2H2(4-6). An understanding of the structure and stability of chlorine on silicon surfaces is essential for a complete description of the surface reaction steps that define plasma etching and epitaxial growth processes. Previous work on chlorine adsorption on silicon surfaces has focused on the nature of the chloride species obtained after various stages of chlorine adsorption. X-ray photoemission spectroscopy (XPS) studies have monitored the silicon oxidation state after a saturation chlorine exposure Si(111)7x7 at 300k. These xps investigations measure oxidation states that were consistent with the bonding one, two and three chlorine atoms to individual silicon surface atoms. The photoemission studies also demonstrated that monochloride species were present at low chlorine coverages and di- and trichloride species were formed at higher chlorine coverages. Only monochloride species were observed to remain on the Si(111) 7x7 surface after annealing to 673 K (7).