Plasma measurements with triple and single probes in an asymmetrical parallel plate rf plasma reactor

Abstract

In an asymmetrical parallel plate reactor measurements of Ar radio-frequency (rf) plasmas are done with both single and triple probes. All measurements are carried out with the same probe construction and the probe systems are realized by changing probe circuit connections. Ar plasmas are generated with a frequency of 13.56 MHz at a pressure of 50 mTorr and a power of 20 W. In order to remove the alternative component the compensation circuits are connected to the probe system. It is found that there is a fairly good agreement between two probe characteristics obtained with the single and the triple probes. Influences of a time variation of the plasma potential on the results are reduced, but cannot be completely removed. The reason why the measurement results obtained with the single and the triple probes suffer from the same effect of the alternative component is explained using the equivalent circuits of the probe systems.