IN-SITU INTERNAL-REFLECTION INFRARED STUDY OF AQUEOUS HYDROFLUORIC-ACID AND ULTRAVIOLET OZONE TREATED SILICON(100) SURFACES

An internal reflection infrared cell has been employed to study aqueous hydrofluoric acid (HF) and ultraviolet (UV)/ozone processing of Si(100) surfaces in situ. The useful range of the infrared experiment was extended below 1500 cm-1 to examine the Si-O-Si asymmetric stretching region by using a thin (75 mum) silicon single crystal in optical contact with a germanium internal reflection element. UV/ozone cleaning produces hydrophilic surfaces by oxidative removal of adventitious hydrocarbon on SiO2 or by oxidation of hydrogen terminated silicon to SiO2. Hydrophobic Si-H terminated surfaces are produced using dilute aqueous HF and are characterized by an increase in the intensity of the Si-H stretching mode and a concomitant decrease in the intensity of the Si-O-Si mode. UV/ozone oxidation of the HF treated surface produces oxidized silicon hydrides while removing Si-H and growing SiO2. Where appropriate, comparisons will be made between the corresponding XPS and infrared spectra to demonstrate the complementary information provided by these spectroscopies.