Investigation of capacitively coupled argon plasma driven at various frequencies and validation of surface waves excitation

The influence of excitation frequency (13.56–96 MHz) on the characteristics of capacitively coupled argon plasma is investigated by means of Langmuir probe and a high-voltage probe. Measurements are performed in argon pressure of 40 and 60 mTorr at a fixed discharge voltage Vpp=200 VVpp=200 V. The measured electron energy distribution function EEPFs are a bi-Maxwellian type irrespective of the driving frequency and gas pressure. The electron density and temperatures show peak over frequency range of 54–72 MHz, beyond which it decreases. The non-monotonic dependences of plasma parameters with driving frequency were interpreted in terms of excited surface wave excited at the powered electrode.

► Driving frequency effect on the EEPF of Capacitive discharge in argon is investigated. ► The EEPFs are a bi-Maxwellian type irrespective of the exciting frequency and gas pressure. ► The electron density and temperatures show peak over frequency range of 54–72 MHz. ► Two interface model analyses suggest propagation of SW on the powered electrode.