Time evolution of electrode voltage distribution in large-area capacitively coupled plasmas

Time evolution of non-uniform voltage distribution on the powered electrode in a large-area very-high-frequency (VHF) capacitively coupled plasma processing system is studied based on a one-dimensional transmission-line model with an equivalent-circuit model of the plasma. With this model, time evolution of voltage and current distributions on the electrode is examined at its activation by the power supply with various frequencies, waveforms, and power-supply locations. It has been found, with the power supply of multiple frequencies, that effects of beat waves can significantly affect plasma uniformity especially if the difference in frequency is small. It has been also demonstrated that, with multiple power-supply locations combined with multiple frequencies, good voltage uniformity over the long electrode can be obtained.