Paper PS-ThP3
Optical and Electrical Diagnostics of an rf-Capacitively Coupled Plasma

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Diagnostic studies of a low pressure rf capacitively coupled plasma in mixtures of Ar and O₂ were performed. This home-made plasma system has a cylindrical chamber with upper and lower annular electrodes; the electrode height can be adjusted. A voltage and a current probe were used to monitor the voltage and the current waveforms on the powered electrode with the focus of investigating the significance of the harmonics for plasma diagnostics. The amplitude, phase shift, and up-to-the 6^th-harmonics of the voltage and current waveforms were recorded. The optical emission of the plasma was monitored using an optical emission spectrometer. It is found in this work that the 3^rd and 4^th harmonics become more prominent in Ar-rich conditions and the waveform shows a significant distortion from the 13.56 MHz sinusoid. Upon changing the electrode positions, the current and voltage waveform amplitude as well as the optical emission intensities of multiple peaks show variations below 20%. The 3^rd and 4^th harmonics in the current waveforms show up-to-50% variations throughout the conditions investigated. This suggests that the harmonic is a more sensitive measure for plasma monitoring. The correlation between operation conditions and diagnostic measurements will be established. The implication of the waveform harmonics to plasma processes will also be discussed.