Interaction of hydrogen-terminated Si(100), (110), and (111) surfaces with hydrogen plasma investigated by in situ real-time infrared absorption spectroscopy

We have used infrared absorption spectroscopy (IRAS) in the multiple internal reflection (MIR) geometry to investigate the interaction of hydrogen-terminated Si(100), (110), and (111) surfaces with hydrogen plasma at room temperature. We have measured infrared absorption spectra in the Si-H stretching vibration region of the hydrogen-terminated surfaces during H-plasma treatment. IRAS data show that at initial stages of H-plasma treatment, surface hydride species (SiHx,x = 1-3) are removed from the surface. A long-term H-plasma treatment of Si(100) and (110) surfaces reproduces monohydride species and creates hydrogen-terminated Si vacancies (VHx) at subsurface regions, i.e., near the surface. On Si(I 11), no hydride species are reproduced even after a long-term H-plasma treatment. We suggest that monohydride is rather stable against attack of hydrogen radicals as compared to higher hydride species, SiH2, and SiH3 . We find that formation of VHx depends on the crystallographic orientation of the Si surface: VHx, formation is more favored on Si(110) than on Si(100), and no VHx, form on Si(Ill). (C) 2003 American Vacuum Society.