Silicon Oxidation Studies: The Role of H 2 O

The thermal oxidation of Si using and ambients has been studied with an automated ellipsometer which can observe the oxidation in situ . The oxidations were carried out in the temperature range of 780°–980°C on <100> oriented single crystal Si. The resulting film growth data was analyzed according to a linear‐parabolic oxidation model. The parabolic rate constant was found to increase abruptly with small additions of to while the linear rate constant increased gradually over the range of added (0–2000 ppm). The over‐all increase in the rate of oxidation due to in was found to be greater than predicted based on the independent diffusion and reaction of and related oxidant species. These effects of were found to be reversible. Therefore, the kinetic role of on the oxidation of silicon is essentially twofold. The acts both as an additional source of oxidant and as an accelerator for the oxidation process involving . It is postulated that this latter effect occurs because the modifies the network thereby enhancing diffusion of the primary oxidant through the film.