Plasma parameters of RF capacitively coupled discharge: comparative study between a plane cathode and a large hole dimensions multi-hollow cathode

Abstract

This work deals with a comparative study of plasma discharge generated by two geometrical configurations of cathodes through an investigation of their plasma parameters. A large hole diameter and depth (D = 40 mm, W = 50 mm) multi-hollow (MH) cathode compared with a plane (PL) cathode are presented for argon capacitively coupled radiofrequency discharge. The electrical characteristics of MH and PL cathodes have been measured in terms of the self-bias voltage (Vdc) while the Langmuir probe was used to measure electron density (ne) and electron temperature (Te) for a wide range of gas pressure (60–400 mTorr) and incident power (50–300 W). It is found that the hollow cathode effect (HCE) is optimum at 60 mTorr with 220 mTorr as a critical gas pressure for which a transition from HCE to insufficient HCE is seen. The electron temperature varies from 3 to 5 eV in the case of MH and PL cathodes with respect to incident power and gas pressure.