XPS AND SIMS STUDY OF ANHYDROUS HF AND UV OZONE-MODIFIED SILICON(100) SURFACES

X-ray photoelectron spectroscopy and secondary ion mass spectrometry are used to study the surface chemistry of silicon single-crystal wafers. Anhydrous HF and UV/ozone processes modify the surface chemistry by altering the concentration and bonding environments of the most abundant surface atoms. The silicon fluoride species decrease with air exposure resulting in mostly oxyfluorides after 1h. Rinsing the fluorinated surface with H2O reduces the fluorine concentration. UV/ozone exposure reduces the hydrocarbon concentration on the HF-etched surface while producing 8 Angstrom, three monolayers, of SiO2. Exposing the HF(g)-treated surface to UV/ozone removes the silicon fluoride species; only oxyfluorides are observed with the ozone-induced SiO2. The cleanest silicon surface with respect to metallic and hydrocarbon impurities was achieved with a HF etch-H2O rinse-UV/ozone oxidation process.