Analysis and characterization of native oxide growth on epitaxial Si1-xGex films after a chemical clean

Ellipsometry, contact angle goniometry, atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) are used to study native oxide growth on SiGe films (with Ge content of 0%, 20%, 40%, and 100%) after a chemical clean. Ellipsometry suggests that the presence of Ce affects the initial oxide thickness right after the clean but it does not affect the rate of native oxide growth, Roughness of SiGe samples as measured by AFM does not appear to be affected by the native oxide growth or the Ge content in the film. The decrease in advancing (and receding) contact angles of SiGe samples after the chemical clean is apparently the result of both increasing oxide thickness and oxide solid phase composition. XPS results suggest that increasing Ge content in the film increases the oxidation of SiGe surface atoms. The chemical shifts in the Si 2p and Ge 3d spectra suggest that both Si and Ge react with oxygen to form SiO2 and GeO2. Such data suggests that contact angle measurements could be a rapid method to determine the state and passivation characteristics of a silicon substrate surface as a function of time, however. such a technique would not be as effective for SiGe films, the chemical composition of their native oxides of which would also change as a function of time. (C) 1997 American Vacuum Society. [S0734-2101(97)02406-8].