ULTRAVIOLET OZONE OXIDATION OF SI SURFACE STUDIED BY PHOTOEMISSION AND SURFACE INFRARED-SPECTROSCOPY

It has previously been shown that ultraviolet (UV) ozone oxidation can be utilized for removing carbon contaminants on Si surfaces and forming a thin oxide film which serves as a protective overlayer for chemical attack. In this study, the UV ozone oxidation of a Si surface has been investigated using photoemission spectroscopy with synchrotron radiation and surface infrared spectroscopy in the multiple internal reflection mode. It is shown that during UV ozone oxidation a thin SiO2 film approximately 5 angstrom thick, which presumably corresponds to one monolayer of six-member rings of SiO4 tetrahedra, is initially formed and subsequently slow oxidation occurs. It is suggested that the formation of this 5-angstrom-thick oxide film is the key to protecting the Si substrate surface from the adsorption of impurities which would occur if the bare Si surface were exposed to air.