Control of High Power Pulsed Magnetron Discharge by Monitoring the Current Voltage Characteristics

Abstract

Key words High power pulsed magentron sputtering, plasma control.Discharge current voltage (IV) curves are directly measured at the target of a high impulse power magnetron sputtering (HiPIMS) plasma for the target materials aluminium, chromium, titanium and copper. These discharge IV curves have been correlated with ICCD camera images of the plasma torus. A clear connection between the change in the discharge IV curve slopes at specific currents and the appearance of localized ionization zones, so-called spokes, in a HiPIMS plasma is identified. These spokes appear above typical target current densities of 2 A/cm 2 . The slope of the discharge IV curves, at current densities when spokes are formed, depends on the mass of the target atoms with a higher plasma conductivity for higher mass target materials. This is explained by the momentum transfer from the sputter wind to the argon background gas, which leads to higher plasma densities for heavier target materials. The change in the VI curve slope can be used to identify the spokes regime for HiPIMS plasmas, as being mandatory for deposition of good quality materials by HiPIMS. Consequently, the discharge IV curve slope monitoring can be regarded an essential control approach of any industrial HiPIMS process, where discharge IV curves are much easier accessible compared to more complex diagnostics such as time and space resolved ICCD camera measurements.

Triple probe interrogation of spokes in a HiPIMS discharge

“…Streak cameras have been used to view spokes side-on so revealing the existence flares (interpreted as electron jets) which emanate from the top of the spoke travelling upwards in columns [21], [26]. Other non-perturbing studies to detect the presence of spokes include monitoring of the changes in the external discharge current-voltage characteristics [13], [27], the use remotely situation mass energy analysers to detect spoke-generated high energy ions [18], [28], including measurements made at right angles to the target [19] and angularly resolved measurements [20]. In addition, non-perturbing flush mounted embedded probes in the target have been developed to measure the current individual spokes deliver to the target [12], [15].…”

Evolution of target condition in reactive HiPIMS as a function of duty cycle: An opportunity for refractive index grading

“…High Power Impulse Magnetron Sputtering (HiPIMS) is a pulsed DC sputtering technique, in which high power is applied to the magnetron target in unipolar pulses at a low duty cycle and a low repetition rate to maintain a manageable average output power. [1][2][3][4][5] The high power pulses generate a high-density plasma in which 40%-80% of the sputtered target material is ionized. [6][7][8][9][10] HiPIMS has been a topic of interest over the past decade, as it combines the advantages of magnetron sputtering with those of an ionized depositing flux.…”

Recent Developments in Accelerated Antibacterial Inactivation on 2D Cu-Titania Surfaces under Indoor Visible Light

“…Depending on the Cu-sputtering time and energy, Cu-clusters are formed that are not necessarily crystallographic, which depend on the affinity between the Cu-atoms and the substrate. During the Cu-atom/ions condensation/coalescence during the formation of the film, sometimes the Cu-nuclei merge on the substrate without forming grain boundaries [123,124].…”