Generation of RF plasma assisted high power pulsed sputtering glow discharge without using a magnetic field

Abstract

High power pulsed sputtering plasma is an emerging technology used to modify the surfaces of industrial components and biomedical parts. The characteristic feature of the plasma is that metallic species are highly ionized and charged particles are magnetized. In order to use the plasma source in a variety of material processing applications, it is desirable that the glow is generated without a magnetic field. In this paper, a sputtering of metallic species is enhanced by a pulsed dc voltage applied to a pair of electrodes immersed in an RF plasma.Sputtered metallic species are ionized as follows: first, a 200kHz-RF (radio frequency, output voltage: 3kV and duration: 200μs) argon plasma is generated. Then, a pulsed dc (direct current) voltage is applied to a pair of electrodes (of 60mm diameter and 75mm long) set in the RF plasma to accelerate argon ions toward the cathode (sputter target). The applied voltage ranges from 0.8 to 1.4kV with negative polarity. The argon gas pressure is 2.7Pa. The pulse width is 60μs. In a typical example, the induced current through the electrode is 45A with a voltage of 1000V. The instantaneous consumed power of 45kW and the energy consumed per pulse is 2.7J, corresponding to an average power of 216W at a repetition rate of 80Hz.