Characterization of ultra-short pulsed discharge plasma for CVD processing

Characteristics of pulsed discharge plasma of methane-hydrogen gas mixture and Ar gas are studied for use in active control of plasma chemical vapor deposition (CVD) processing. Voltage-current characteristics, time lag of the current pulse, and the photon emission intensity profile investigated using high-voltage pulses of 50-1000 ns duration. In such a pulsed discharge, voltages much higher than those in a DC glow discharge can be applied without any plasma nonuniformity or arcing because voltage amplitude falls to zero before the glow-to-arc transition. A current value of more than 10/sup 3/ times those in a flow discharge can be established. Very high photon emission intensity from CH radicals and H ions are observed near the anode in a pulsed plasma. This is different in DC plasma, where the negative glow region near the cathode is the brightest.<
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