Reliability evaluation of ultrathin gate oxides grown on Si wafers stored in clean stocker with a UV/photoelectron source

With scaling down of the size of semiconductor devices, the influence not only of particles but also of gaseous contamination becomes serious in semiconductor manufacturing processes. UV/photoelectron method, by which particles are charged by photoelectrons from UV irradiated metal surface and collected on electrodes by an electric field, is effective not only for particles but also for gaseous contamination such as, NH/sub 3/, NO/sub X/, SO/sub 2/ and organic compounds. By attaching photocatalyst (TiO/sub 2/) with UV/photoelectron source (photocatalyst method), the gaseous contamination is more effectively reduced. We investigate the influence of gaseous contamination on the gate oxide reliability. By protecting the Si wafer from carbon contamination using the UV/photoelectron or the photocatalyst method, the reliability of gate oxides is improved.