Ion temperature and velocity in a 300 mm diameter capacitively coupled plasma reactor driven at 13, 60 and 162 MHz

Abstract

Spatially resolved temperature, radial drift velocity and relative density of an argon ion metastable state were measured in a capacitively coupled, parallel-plate reactor. The argon plasma was generated using single-frequency excitation of 13, 60, 162 MHz and dual frequency excitation of 13 and 60 MHz. For the conditions investigated, the ion temperatures were between 400 and 750 K. At the lower excitation frequencies of 13 and 60 MHz, the radial ion velocity increased monotonically from the center of the plasma to the edge of the electrode while ion temperature did not depend strongly on radial position or frequency. At 162 MHz excitation, the radial ion drift velocity peaked off center and the ion temperature showed large variations with radial position. For all cases, the radial drift velocity was less than the average thermal velocity. At all drive frequencies, the ion temperature was only a weak function of pressure and rf power. Comparison of the ion temperature and the drift velocity suggests that for 162 MHz excitation, the ion heating mechanism may depend on the radial position.