Anodic Oxidation of Narrow Region of Silicon Substrate

Anodic oxide films were formed on comparatively small area of silicon substrates. Constant current mode of anodization has been used for oxidation，but during oxidation processes，the current density has been changed to go through one or more stepped transitions either step-up or step-down before the completion of the processes. This modified mode of constant current anodization showed to be effective in reducing the interface state density of a silicon/silicon-oxide system. Among the various stepped transitions in the modified mode of constant current anodization，step-down transition of current density was found to be optimum in reducing the interface-state density. The structure and composition of SiO₂/Si interface regions for both large-area oxide and narrow-area oxide were also investigated by X-ray photoelectron spectroscopy (XPS). The composition of SiO₂/Si interface of narrowarea oxide showed less stoichiometry than that of large-area oxide