Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering

Abstract

Transition between the discharge regimes of high power impulse magnetron sputtering and conventional direct current magnetron sputtering, 2009, PLASMA SOURCES SCIENCE and TECHNOLOGY, (18) AbstractCurrent and voltage have been measured in a pulsed high power impulse magnetron sputtering (HiPIMS) system for discharge pulses longer than 100 µs. Two different current regimes could clearly be distinguished during the pulses: (1) A high-current transient followed by (2) a plateau at lower current.These results provide a link between the HiPIMS and the direct current magnetron sputtering (DCMS) discharge regimes. At high applied negative voltages the high-current transient had the characteristics of HiPIMS pulses, while at lower voltages the plateau values agreed with currents in DCMS using the same applied voltage. The current behavior was found to be strongly correlated with the chamber gas pressure, where increasing gas pressure resulted in increasing peak current and plateau current. Based on these experiments it is here suggested that the high-current transients cause a depletion of the working gas in the area in front of the target, and thereby a transition to a DCMS-like high voltage, lower current regime.Confidential: not for distribution.

An introduction to thin film processing using high-power impulse magnetron sputtering

“…The loss of process gas results in a reduction of ions available for sputtering (often Ar ions) leading to a reduced deposition rate as well as a reduction of plasma density, which means that the desired IPVD properties will be lost. 29 The reduction of gas density would not be much of a problem if the refill process would be fast enough. Unfortunately, this does not seem to be the case in all types of magnetron discharges, 29 and it is believed to be particularly serious in HiPIMS due to the high peak power densities, 61 which is further investigated and discussed in more detail in Ref.…”

“…29 The reduction of gas density would not be much of a problem if the refill process would be fast enough. Unfortunately, this does not seem to be the case in all types of magnetron discharges, 29 and it is believed to be particularly serious in HiPIMS due to the high peak power densities, 61 which is further investigated and discussed in more detail in Ref. 29.…”

“…Unfortunately, this does not seem to be the case in all types of magnetron discharges, 29 and it is believed to be particularly serious in HiPIMS due to the high peak power densities, 61 which is further investigated and discussed in more detail in Ref. 29. Also, a fraction of reflected gas neutrals moving away from the target surface will collide with the neutral background and thereby enhance the gas rarefaction.…”

“…Last, note that neutral gas atoms are also rapidly lost through direct ionization during the HiPIMS pulse. 29 This is a process, where gas ions arriving at the target become neutralized and reflected in the sputtering event, but are energetic enough to pass quickly through the near-cathode region and thus effectively drain the ionization region of process gas. To what extent it affects the overall gas depletion remains to be investigated.…”

“…29 Konstantinidis et al 28 have shown that by decreasing the pulse length it is possible to increase the deposition rate, where ;70% of the DCMS deposition rate is achieved for 5 ls pulses in the case of Ti compared to ;20% of the DCMS deposition rate for 20 ls pulses, mainly due to less self-sputtering for short pulses. At the same time there is a tradeoff with the degree of ionization, where the highest reported values are found for the 20 ls pulses.…”