An improved UV/ozone oxidation system

Several modifications were made to a commercial W-ozone stripper/cleaner in an effort to improve UV/ozone technology. Heating of the sample platform was done with radiant heaters instead of a resistance heater. Quartz infrared heat lamps and a metal ribbon radiant heater significantly shortened the heating-cooling cycle relative to a resistance heater; the lamps also heated the sample platform uniformly. With the radiant heaters, samples of different thickness could easily be processed. A cold cathode UV grid lamp provided more uniform illumination of the sample support platform than did the standard hot cathode spiral lamp. The grid lamp also reached steady state power output sooner than the spiral lamp. A polymeric membrane was found to be an effective diffuser for ozone/oxygen mixtures and there was no apparent degradation of the membrane due to exposure to UV/ozone. Furthermore, it is anticipated that the membrane diffuser would prevent any particles larger than 0.2 mu m (the average membrane pore size) from entering the W-l reaction chamber. The performance characteristics of the modified system are presented.