Effect of 13.56MHz low-frequency power on electrical characteristic of 60MHz radio-frequency capacitively coupled plasma

Abstract

Dual-frequency capacitively coupled plasma (DF-CCP) driven by two frequencies of 60MHz and 13.56MHz was studied using compensated Langmuir probe technique. The change of EEPF with radial position and low-frequency input power was obtained. The experimental result shows that the input power of 13.56MHz mainly affects the population of low-energy electrons and the effect becomes greater when the gas pressure increases. The EEPF exhibits a structure of bi-energy-peak beyond the centre of discharge. The second energy peak drifts to the region of higher electron energy from the centre to the edge of electrode. The emergence of second energy peak could be attributed to the enhanced heating of middle-energy electrons. The electron density and electron temperature were calculated using EEPF. The plasma electron heating mechanism was discussed.