The transition from symmetric to asymmetric discharges in pulsed 13.56 MHz capacitively coupled plasmas

摘要: The behavior of a rapidly pulsed radio-frequency capacitively coupled parallel plate reactor has been investigated using time-resolved voltage probe, microwave interferometer, and optical emission techniques. was operated with 50 mTorr argon 100 W rf power (measured at the generator) 13.56 MHz supplied to 100-mm-diam powered electrode, pulse durations 25 μs. For low repetition rates (50 Hz) envelope characteristic form which entitled “Bird’s Head.” There is no plasma present beginning pulse, so that an initial breakdown phase occurs. This lasts about 600 ns, after time density sufficiently high for Debye length enter gap between electrodes sheaths on electrodes. In asymmetric reactors blocking capacitor in matching circuit charges such electrode acquires continuous negative offset (the so-called dc bias). th...