Studies on electron heating and transport mechanism in capacitive coupled plasma

Abstract

The research presented here focuses on the study of phenomena associated with the rf power absorption, electron heating and transport in local or non-local regimes. To investigate the study rf current-voltage monitoring system and rf-compensated Langmuir probe system are developed. Experiment has performed in wide range external parameters, various gas pressures, frequencies, gases, magnetic fields, powers, grid-biases, and gap sizes. From the monitoring of the discharge current-voltage, we found the capacitive discharge dissipate most of the rf power through the ion motion in the sheath rather than electron motion in the bulk at low frequency, while the capacitive discharge dissipate most of the rf power through the electron motion in bulk at high frequency. As a result, the mode transition for rf power dissipation from ion dominated dissipation to electron dominated dissipation takes place while increasing the driving frequency. This is due to the fact that sheath resistance corresponding the power dissipation by ion in the sheath decreases greatly with driving frequency. To conform the argument, we theoretically investigate transition with a simple circuit model and PIC simulation. Both theoretical result is in a good agreement with the experimental result. The transverse magnetic field also induced the similar transition mentioned above. As the magnetic field increases, the electron motion to the surface well which is perpendicular to the field line is strongly reduced, so that self-bias (dc-sheath voltage) in the sheath decreases. Because the self-bias is directly related to the rf dissipation by the ion ($P_{ion} ∝ V_{self}ㆍI_i$), the rf power dissipation in the sheath decreases strongly with the magnetic field. As result, rf power dissipation mode transition from the ion dominated dissipation to electron dominated dissipation is induced by increasing the magnetic field. Gas species effect on the rf power dissipation mode transition is investig...