Selective Etching of Silicon in Preference to Germanium and SiGe.

The selective etching characteristics of silicon, germanium, and SiGe subjected to a downstream H/CF/Ar plasma have been studied using a pair of in situ quartz crystal microbalances (QCMs) and X-ray photoelectron spectroscopy (XPS). At 50 °C and 760 mTorr, Si can be etched in preference to Ge and SiGe, with an essentially infinite Si/Ge etch-rate ratio (ERR), whereas for Si/SiGe, the ERR is infinite at 22 °C and 760 mTorr. XPS data showed that the selectivity is due to the differential suppression of etching by a ∼2 ML thick CHF layer formed by the H/CF/Ar plasma on Si, Ge, and SiGe.

Formation of atomically ordered and chemically selective Si-O-Ti monolayer on SiGe(110) for a MIS structure via HO(g) functionalization.

SiGe(110) surfaces were passivated and functionalized using atomic H, hydrogen peroxide (HO), and either tetrakis(dimethylamino)titanium (TDMAT) or titanium tetrachloride (TiCl) and studied in situ with multiple spectroscopic techniques. To passivate the dangling bonds, atomic H and HO(g) were utilized and scanning tunneling spectroscopy (STS) demonstrated unpinning of the surface Fermi level. The HO(g) could also be used to functionalize the surface for metal atomic layer deposition.