On the heating mode transition in high-frequency inductively coupled argon discharge

In high-frequency inductively coupled argon discharges with a planar-type coil the phenomena of discharge mode transition (E-H mode transition) are investigated. Experimental observation is done at the low pressure of 10 mTorr and the high frequency of 19 MHz over a range of rf power, 40-525 W. First of all, the discharge mode transition is observed through a change of luminous intensity. This transition is found to occur at the relatively high power of about 280 W compared with the mode transition in a 6.5 MHz discharge. Also, some distinctive features are compared to low-frequency discharges during this transition. In particular, during the E-H mode transition the apparent changes of plasma potential are observed and the sudden variation of plasma potential is proposed as an important factor that indicates the change of power coupling. The features of the discharge mode transition in high-frequency discharge are discussed by considering the power coupling ar: each mode by measurements of the electron energy distribution functions. (C) 1999 American Institute of Physics. [S1070-664X(99)02002-9].