Cathode voltage and discharge current oscillations in HiPIMS

Abstract

Thispaper reports on the oscillations both on the cathode voltage and on the discharge current which emerged suddenly and simultaneously during ahigh-power impulse magnetron sputtering pulse. Detailedexperiments identified the pressure and the discharge current ranges to detect these oscillations. The oscillationsoriginatedfrom the magnetized plasma and their frequency ranged from 225 kHz to 400 kHz depending on the experimental conditions. Simultaneous measurement of both oscillations and spokes was conducted to find mutual correlations. The oscillations always accompanied the spokes and no particular conditions to detect oscillations in theabsence ofspokes were found. The oscillations were not caused by the rotational motion of the spokes butemerged when acertain threshold amount of spokes was overreached.

Single-shot spatial-resolved optical emission spectroscopy of argon and titanium species within the spoke

“…Considering the race track circumference of 14 cm and based on earlier measurements [26] the mode number of approximately 8 is expected. This provides us with the spoke velocity of about 5 km s −1 , which is in agreement with reports for similar pressures [44]. The range of the relative spoke size of 3-8 µs, which was chosen for the data processing, corresponds to the spoke mode number range of 4-9.…”

“…The generator is equipped with Melec Measurement System MS-500-D-TB for discharge current and cathode voltage measurements. To acquire a stable plateau of the discharge current, an 1 Ω ballast resistor was integrated into the HiPIMS generator output in series with a cathode [30,44]. Thus, the added resistor worked as negative feedback limiting the rise of the discharge current.…”

Corrigendum: Evidence of ion energy distribution shift in HiPIMS plasmas with positive pulse (2019 Plasma Sources Sci. Technol. 28 01LT03)

“…F Avino https:/ /orcid.org/0000-0002-6206-0960 The large fraction of ionized sputtered atoms in plasmas obtained with High Power Impulse Magnetron Sputtering (HiPIMS) is making this technique very attractive for a constantly increasing number of fields [1][2][3][4][5][6]. The scientific community is devoting a significant effort to investigate and unveil the physical mechanisms of HiPIMS plasmas [7][8][9][10][11], as well as to explore the advantages with respect to well known sputtering techniques such as Direct Current Magnetron Sputtering (DCMS) [12,13]. Very recently, the effects of a positive voltage pulse (PP) applied to the target after the main negative pulse in the HiPIMS regime have started to be explored [14,15].…”

The statistics of spoke configurations in high-power impulse magnetron sputtering discharges

“…A few years ago, it was observed that the plasma is not always homogeneously distributed over the racetrack area of the target in high-power impulse magnetron sputtering (HiPIMS) discharges [1][2][3], but under certain conditions it is self-organised into ionisation zones called spokes [2,4]. Several non-perturbing diagnostic techniques have been used to investigate spokes; these include photo-multiplier tubes [3,[5][6][7][8], high-speed 2D imaging of broadband emission [1][2][3][5][6][7][8][9][10][11][12][13][14][15][16][17][18], spectrally filtered high-speed 2D imaging [19][20][21], streak cameras [21][22][23][24], laser-induced fluorescence [20] and embedded probes [13,25,26]. Furthermore, more perturbing methods such as the Langmuir probe (single as well as multiprobe) [3,[5][6][7][8], emissive probe [2], magnetic sensor probe [27] or triple probe…”

“…The spoke mode number, i.e. the number of spokes, was studied for various target materials by different groups [5,7,9,10,14]. It was found that in different experimental configurations contradicting results may be obtained.…”