Feedback control of a polymer producing glow discharge plasma

Abstract

Glow discharges are produced in a conventional parallel-plate device using either propylene or argon. The propylene discharge differs from the argon discharge in that polymers are continuously deposited at the plasma boundaries. Discharges with plasma densities of approximately 10/sup 9/ cm/sup -3/, T/sub e/ approximately=3 eV are produced at neutral pressures of approximately 300 mtorr at RF frequencies of approximately 100 kHz. The device consists of two parallel plates (diameter=7.5 cm, separation approximately 5 cm). Langmuir probe current-voltage (I-V) characteristics are monitored with a heated mesh probe. A PC monitors the I-V characteristic every 30 s and adjusts the gain of the glow discharge RF amplifier to maintain a desired I-V characteristic as wall conditions, etc. change.<>