Ultrathin oxide film formation using radical oxygen in an ultrahigh vacuum system

Radical oxidation at a thickness of less than 2.0 nm in an ultrahigh vacuum system with an electron cyclotron resonance plasma has been studied. Atomic force microscopy and grazing-incidence X-ray reflectrometry were used to evaluate the interface roughness and oxide density, respectively. The interface roughness at a thickness of 1.8 nm, measured by the root mean square, was 0.11 nm. The density of the radical oxide decreased as the oxide thickness decreased, especially at less than 2.0 nm. However, the density of the radical oxide annealed in molecular oxygen at 5 x 10(-3) Torr and T-sub = 750 degrees C increased without an increase in oxide thickness.