GROWTH AND CHARACTERIZATION OF ROOM-TEMPERATURE ANODIC SIO2-FILMS

The anodic behavior of Si in dilute NH, solutions has been investigated with the aim of producing thin gate oxides of thickness between 4 and 15 nm. The oxide is formed under potentiostatic conditions and in varying solution concentrations. The thickness is calculated from x-ray photoelectron spectroscopy (XPS) which has been calibrated with nuclear reaction analysis, using the O-16(d,p) O-17 reaction. The anodic growth process yields very clean oxide, contaminated only with adventitious carbon on the surface as well as less-than-or-equal-to 1 at. percent nitrogen within the bulk (as detected by XPS). The nitrogen impurity is present in various oxidation states depending on the formation conditions. Its concentration can be decreased by annealing the samples, decreasing the concentration of NH3 in solution, or by cathodic reduction. The growth mechanism has been investigated using the technique of O-18 labeling with analysis by secondary ion mass spectroscopy