Measurement and control of RF power in inductively coupled plasma

Summary form only given, as follows. Inductively coupled plasma (ICP) sources are of growing importance for industrial applications in plasma aided manufacturing and lighting technology. To generate an experimental data base over the wide range of external discharge conditions needed to carefully study such discharges (power, gas pressure and frequency), accurate measurement techniques together with discharge stability are essential. A low-loss, multi-frequency matcher operating at 3.39, 6.78 and 13.56 MHz, with tuning and matching functions that are practically independent, has been designed to drive a cylindrical ICP maintained with a planar (pancake) induction coil. The matcher has built-in current transformers and voltage dividers for phase resolved measurements at the input and output of the matcher. These measurements together with the measured coil temperature allow one to determine matcher and coil losses in order to accurately evaluate rf power dissipated in the plasma. These measurement instruments are connected and controlled through a computer which provides continuous monitoring of discharge characteristics and control of the rf power actually deposited in the plasma. Data that demonstrates the variation of power loss in the matcher and the coil over a wide range of rf power and gas pressure will be presented.