Kinetics of UV/O2 Cleaning and Surface Passivation: Experiments and Modeling

ABSTRACTRemoval of adsorbed organic contaminants from Si surfaces by reaction with molecular O3 and photo-generated atomic oxygen species in a UHV-compatible photochemical reactor was investigated. Treatment of contaminated wafers with externally generated O3 at 25°C was effective in removing adsorbed organics, but surface cleaning rates were enhanced by simultaneous 254-nm UV irradiation of the reactor contents. In situ photo-generation of O3 and atomic oxygen species by 185- and 254-nm irradiation of O2 gave comparable results. A simplified gas-phase kinetics model describing O3 generation by a low-pressure Hg lamp was developed and used to gain insight into the effects of relative humidity and O2 partial pressure on steady-state O3 concentrations.