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 V-pp = 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. (C) 2012 Elsevier B.V. All rights reserved.