LOW TEMPERATURE OF PLASMA TREATMENT FOR STERILIZATION

The purpose of this study was to rapidly degrade and remove organisms in a gas atmosphere in a high frequency plasma state.1)Photoresist was applied to wafers，and plasma treatment was performed with oxygen gas。The film thickness of the resist was measured using a film thickness scale.The film thickness more markedly decreased for wafers vertically placed in the quartz rack than for those horizontally placed，at a higher output，and using opposed electrodes than coaxial electrodes as a discharge method.2)Specimens to which bacterial spores were applied were plasma-treated by the opposed electrode method and cultured in Triptocase medium。The sporicidal effects were more marked using a longer treatment time，higher output，and a higher heater temperature。All10plasma-treated specimens for ten min(heater temperature，60-C)to which10^4B.Stearothemophilus was applied were negative for culture.All non-plasma-treated specimens(heater temperature，60℃，100℃，and 140℃)were positive for culture.3)The mechanism of hydrogen peroxide/low temperature plasma sterilization system(ST system：STERRAD*100R，Johnson&Johnson)was evaluated。A biological indicator(BI，Johnson&Johnson)and a power source were placed in the chamber。The power supply was deliberately terminated 25minutes before the treatment completion time indicated by the display panel to skip the plasma treatment process。All10cultured BI specimens were negative。These results suggest that sterilization has been already completed before the plasma treatment process，and sterilization primarily depends not on plasma but on the pharmaceutical effects of hydrogen peroxide in the ST system.Our apparatus allows sterilization only with plasma without the pharmaceutical effects of hydrogen peroxide.

The purpose of this study was to rapidly degrade and remove organisms in a gas atmosphere in a high frequency plasma state.1) Photoresist was applied to wafers, and plasma treatment was performed with oxygen gas. The film thickness of the resist was measured using a film thickness scale. The film thickness more markedly decreased for wafers vertically placed in the quartz rack than for those horizontally placed, at a higher output, and using opposed electrodes than coaxial electrodes as a discharge method.2 ) Specimens to which bacterial spores were applied were plasma-treated by the opposed electrode method and cultured in Triptocase medium. The sporicidal effects were more marked using a longer treatment time, higher output , and a higher heater temperature. All 10 plasma-treated specimens for ten min (heater temperature, 60ーC) to which 10^4 B. Stearothemophilus was applied were negative for culture. All non-plasma-treated specimens (heater temperature, 60℃, 100℃, and 140℃) were positive for culture.3 ) The mechanism of hydrogen peroxide/low temperature plasma sterilization system (ST system : STERRAD*100R, Johnson ＆ Johnson) was evaluated. A biological indicator (BI, Johnson ＆ Johnson) and a power source were placed in the chamber. The power supply was deliberately terminated 25 minutes before the treatment completion time indicated by the display panel to skip the plasma treatment process. All 10 cultured BI specimens were negative. These results suggest that sterilization has been already completed before the plasma treatment process , and sterilization primarily depends not on plasma but on the pharmaceutical effects of hydrogen peroxide in the ST system.Our apparatus allows sterilization only with plasma without the pharmaceutical effects of hydrogen peroxide.