Crystallographic dependence of SiOX transition layer evolution during native oxide formation on silicon surfaces

The formation of native oxide on silicon surfaces is an unavoidable phenomenon that critically influences subsequent semiconductor fabrication processes, particularly for advanced devices requiring precise interface control. While the orientation-dependent oxidation behavior has been extensively studied under thermal oxidation, the native oxide evolution formed spontaneously at room temperature has yet to be fully elucidated. In this study, the native oxide growth behavior on Si(110) and Si(100) surfaces was preliminary evaluated as a function of storage time under identical conditions. X-ray photoelectron spectroscopy (XPS) was primarily employed to investigate the evolution of intermediate suboxide species within the SiO X transition layers formed after final cleaning on both Si(100) and Si(110) surfaces. The result reveals a strong crystallographic dependence on native oxide growth, in which the oxidation behavior of both surfaces increases as a function of storage time. Notably, the Si 4+ component exhibits significantly higher relative intensity on Si(110), becoming detectable shortly after cleaning. This indicates a faster native oxide formation compared to Si(100), where the ratio of their initial oxide thicknesses (0.19 nm and 0.04 nm) is approximately 4.8 times. Spectroscopic ellipsometry measurement shows a consistent trend with the XPS data that demonstrates an increase of oxide thickness as a function of the storage time. The accelerated oxidation on Si(110) is attributed to its higher density of dangling bonds and distinct surface atomic configuration, which are rapidly promoting the oxygen adsorption and oxide formation. These findings demonstrate the higher environmental sensitivity of the Si(110) surface and provide important insights into surface preparation and native oxide control for next-generation semiconductor device fabrication.