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

Surface Photovoltage Monitoring of Heavy Metal Contamination on Silicon During Chemical Cleaning in IC Manufacturing

The principles and application examples of recently refined，computerized surface photovoltage (SPV) method are described. The SPV method was used to optimize cleaning efficiency and to monitor \u27in-line\u27 heavy metal contamination and charge during critical processing steps for Statistical Process Control (SPC). Examples of the optimization of various cleaning steps，effects of the purity of virgin and reused chemicals， and the surface topology on cleaning efficiency will be given together with examples of SPC monitoring of real problems in processing lines. Cleanliness of incoming chemicals is not always a limiting factor and often is not related to the cleanliness of chemicals at the point of use (in the cleaning station). This new method is capable of waferscale，non- contact mapping of metal contaminants in the bulk and on the surface with sensitivities as high as 10¹⁰atoms cm-³