ROLE OF EXCITATION-FREQUENCY IN A LOW-PRESSURE, INDUCTIVELY-COUPLED RADIOFREQUENCY, MAGNETIZED PLASMA

We have experimentally studied the role of the excitation frequency f( rf) in a low-pressure, inductively coupled radio-frequency (rf), magne tized plasma. Planar Langmuir probe measurements of the electron energ y distribution function and the plasma density n(e) clearly demonstrat e a sudden change in the nature of plasma-rf coupling as f(rf) approac hes the electron cyclotron frequency f(ce) from below or above. The ob served mode change is qualitatively explained by different wave coupli ng mechanism for f(rf) < f(ce) and f(rf) > f(ce). These observations c ould have important applications for plasma processing.