AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP9
EEPF Measurement in SF6/O2 and CF4/O2 Gas Mixture Capacitively Coupled Plasma

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: High Pressure Discharges and Novel Diagnostics & Sources Poster Session
Presenter: S.K. Ahn, Korea Advanced Institute of Science and Technology, Republic of Korea
Authors: S.K. Ahn, Korea Advanced Institute of Science and Technology, Republic of Korea
S.J. You, Korea Advanced Institute of Science and Technology, Republic of Korea
H.-Y. Chang, Korea Advanced Institute of Science and Technology, Republic of Korea
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We have been measured the plasma parameters and EEPF (Electron Energy Probability Function) in a capacitive discharge with some mixtures of processing gases, such as SF6/O2 and CF4/O2. The measurements were achieved at various gas mixing ratios under constant discharge current and pressure conditions. Through the experiment, we have found that as the mixing ratio of SF6 increase, the effective electron temperature increases, while the electron density decreases. And in case of CF4 mixing, the variation trend of the effective electron temperature and the electron density is very similar to that of SF6 mixing case. Thus, it apparently looks like mixing SF6 or mixing CF4 in O2 discharge affect the plasma parameters with similar discharge physics. However in our EEPF measurement, it has been found that mixing SF6 and mixing CF4 in O2 discharge influence the plasma with quite different manners. The low energy part of EEPF is depleted in both case of increasing SF6 mixing ratio and increasing CF4 mixing ratio. But the high energy electron population in EEPF only depends on SF6 mixing ratio. That is, the high energy electron population in EEPF is enhanced with increasing SF6 mixing ratio, while almost independent of CF4 mixing ratio. These gas mixing effects can be analyzed by considering elastic collision and vibrational excitation collision between electrons and the fluoride gases.