This paper presents a study on the measurement of particle fluxes (Al, Al+, Cr, Cr+, Ar+) at the substrate position during magnetron sputtering deposition. The fluxes were investigated for pure aluminium and chromium targets, as well as their alloy. The industrial magnetron deposition system employs a novel focused magnetron sputtering technique, where only a small portion of the cylindrical target is sputtered at a given time because the plasma is confined to a narrow ring enclosing the target and, thanks to movable magnets, periodically moves over the entire length of the cylinder. This arrangement enables very high power densities (similar to 625 W.cm-2) to be achieved using a continuous direct current power supply. Using a biasable quartz crystal microbalance system, both atomic and ionic fluxes of the metal particles were quantified. The same system, configured as a flat Langmuir probe in a saturated ion flux region, was also used to measure the total ion flux. To differentiate between the aluminium and chromium fluxes sputtered from the alloy target, Rutherford backscattering spectrometry of the deposited samples was used. This pioneering approach enables the quantification and differentiation of atomic and ionic species of film-forming elements, as well as the argon ion flux, which are critical parameters in thin-film deposition. Despite the ionised metal flux fraction of the sputtered species reaching around 15%, the flux of metal ions on the substrate is ten times lower than that of argon ions.

Deposition conditions in laboratory and industrial PVD processes can differ significantly. However, these differences are rarely quantified directly at the substrate. In this work, the fluxes of neutral Ti atoms, Ti ions, and Ar ions were measured at the substrate position for four representative deposition conditions: laboratory DC magnetron sputtering, laboratory HiPIMS, industrial DC magnetron sputtering, and industrial cathodic arc deposition. All processes were studied under conditions characteristic of their typical use, capturing realistic laboratory and industrial operation, and a unified diagnostic approach was employed to enable direct comparison. The results reveal pronounced differences between laboratory and industrial conditions, as well as between individual deposition techniques. While laboratory DC magnetron sputtering is characterised by weak metal ion bombardment and a neutral-dominated flux, its industrial counterpart operates under markedly different conditions, with significantly higher ion fluxes. HiPIMS enhances metal ionisation, but still results in an ion flux dominated by Ar+ ions, indicating that increased ionisation in HiPIMS does not necessarily lead to metal-ion-dominated bombardment. Industrial DC magnetron sputtering and laboratory HiPIMS exhibit similar ionisation levels of sputtered species as well as comparable total ion flux impacting the substrate, highlighting an unexpected similarity between fundamentally different plasma excitation modes. In turn, processes of the same designation operated in laboratory and industrial environments do not necessarily result in similar conditions on the substrate. This necessitates direct characterisation of particle flux to understand the actual thin-film growth conditions and enable consistent comparison between different PVD processes.

Three different approaches for using high power impulse magnetron sputtering (HiPIMS) with a titanium target were examined in terms of plasma diagnostics and coating properties. In all three approaches, a 1 kW average power was kept constant. The first approach involves splitting a strong single HiPIMS pulse into multiple evenly distributed weaker pulses by proportionally dividing the period. The second approach is based on the first one, but the pulses are grouped together in a short burst, or pulse package, where the overall period is conserved. Comparing the second approach to the first enables the identification of the effect of pulse grouping. In the third approach, the pulses are also grouped into the pulse package, however, the period is extended proportionally to the number of pulses in the pulse package. This allows for the creation of short bursts of energetic pulses separated by very long off-times while maintaining the duty cycle. In this way, it is possible to determine whether the grouping of the strong pulses into a pulse package is more beneficial for the deposition than the negative effects induced by prolonging the off-time. Plasma diagnostics revealed that grouping the pulses into packages in the second approach resulted in a higher ionised metal flux fraction on the substrate compared to the first approach, which led to stronger ion bombardment of the growing coating, resulting in denser coatings and changes in the crystalline microstructure. The third approach did not increase ionised metal flux fraction significantly but influenced the texture and grain size of the growing films.

Magnetron sputtering is one of the cornerstones of thin film-forming methods. The literature provides excessive knowledge about inner plasma processes, deposition control and thin film growth, but the overwhelming majority reports on results conducted on a small lab scale. To transfer this knowledge and use it in industrial applications, one has to overcome many challenges, the most profound being scaling the process from the lab scale towards a large industrial scale. This paper explores the critical differences in deposition fluxes and ionisation of metals when scaling from lab to industrial systems. While in the laboratory, the direct current magnetron sputtering does not create sufficient metal ions, this is dramatically different in the industrial system, where up to 30% of the film-forming species detected were ions. Additionally, the deposition rate in the industrial system was about one order of magnitude higher compared to the laboratory system.

Investigating spokes in high-power impulse magnetron sputtering discharge requires non-invasive diagnostic methods to characterise accurately spoke properties. A fast photodiode and a cylindrical Langmuir probe were employed to synchronise the moment of acquisition of the optical emission spectrum with the position of a passing spoke. This study provides statistical data analysis to bring insights into spoke characteristics in a non-reactive argon atmosphere, employing aluminium, chromium, copper, titanium, and tungsten targets. Utilising different target materials, the objective is to describe basic parameters such as shape, length, and propagation velocity of spokes and also analyse spoke inner parameters such as floating potential and spectral emission, under nearly identical experimental conditions. From the optical emission, the most prominent species within the spoke were determined. Additionally, the mechanism governing spoke movement was described using a phenomenological model.

In the industry, there is a preference for robust and technologically straightforward solutions that can deliver desired products at reasonable costs. This study introduces a reliable, robust, and cost-effective ion-assisted thin film growth technique called moving focused magnetic field magnetron sputtering. At the core of this technology lies the generation of dense plasma within a small area of the target and the controlled movement of this plasma across the entire target surface. The deposition process, powered by a direct current generator, behaves similarly to high-power impulse magnetron sputtering and yields coatings with properties comparable to those produced by this method. Notably, this study marks the first application of an ion meter to measure the ionized metal flux fraction of sputtered titanium at industrial conditions, revealing values of up to 34% measured at the substrate position.

In industrial magnetron sputtering processes, large DC-driven cathodes are commonly employed. This work reports on industrially compatible technology, which allows for the increase in ionized metal flux fraction on the substrate in a controlled manner without sacrificing the deposition rate. From the long arc cathode positioned on the one-hand side of the magnetron cathode, electrons are drawn towards the anode on the other side. This arrangement induces a large volume secondary discharge that extends along the entire length of the magnetron cathode, effectively ionizing sputtered species as they traverse this discharge towards the substrate. With this setup, while sputtering titanium in an argon atmosphere under industrial conditions, up to 28% of ionized metal flux fraction was achieved on the substrate position. This technology significantly improves the quality of the deposited coating, including hardness, Young’s modulus, roughness and fracture resistance, as shown in the TiN case study.

The behavior of the ground state neutral and singly ionized atoms is studied in multipulse high power impulse magnetron sputtering processes. The time-resolved two-dimensional laser induced fluorescence was used for imaging the discharge volume (density mapping) during the plasma-on and plasma-off time phases. The role of the number of micropulses and delay time between the micropulses in the pulse package is analyzed and discussed systematically. In addition, the propagation of the sputtered particles from the target is investigated.

Bipolar high power impulse magnetron sputtering introduces new possibilities to affect positive ions created during the negative discharge pulse in order to tailor thin films with specific parameters. This paper studies plasma emission in different experimental conditions during different phases of the positive pulse with spectral, spatial and temporal resolution. It is found that predominantly the working gas gives rise to plasma emission during the positive pulse. The plasma emission is observed only in regions of low magnetic confinement, forming a 'mushroom-like' shape in the middle of the target or a 'dome-like' shape on the outer parts of the target. An explanation of the discharge kinetics is proposed based on the acquired data.

Magnetron sputtering in an argon and hydrocarbon gas mixture is a complex deposition process exhibiting features of both physical vapour deposition and plasma enhanced chemical vapour deposition. The hydrocarbon gas decomposes within the plasma and then it is able to form a carbide phase with the target metal atoms or to be deposited as amorphous carbon. In this paper, a simple model for both the direct current (dcMS) and the high power impulse magnetron sputtering (HiPIMS) processes with hydrocarbon gas admixture is presented. The sputtered target racetrack is divided into metallic, compound, and carbon fractions to take into account both the carbide formation and the carbon deposition. To simulate the HiPIMS process, the back-attraction of ionised sputtered metal particles is incorporated into the model. The model is cross-validated with the previously published experiments which were conducted using the same deposition apparatus allowing for the direct comparison of the dcMS and HiPIMS processes. The simulated results correlate with the measured dependencies of the deposition rate, the carbon content in deposited films, and the racetrack fractions on the acetylene supply rate. The presented model is further successfully validated with the evolution of the racetrack composition calculated by SDTrimSP.

Understanding mechanisms behind the formation and propagation of ionisation zones, so-called spokes, have been highly important since the first observations in high power impulse magnetron sputtering discharges. To this day, however, a complete description is still lacking. This contribution gives an insight into the spokes in reactive Ar–N2 atmosphere using titanium target. The aim of this study is to describe not only global parameters of spokes such as their shape, length and propagation velocity but also provide a description of parameters evolving over the spoke, such as floating potential and spectral emission. The measurements of the latter clearly showed which species emission is most prominent and how it changes with transition from non-reactive argon discharge towards the discharge driven in a pure nitrogen atmosphere. Implications on the gas dynamics and discharge transitions are discussed.

The rotating plasma patterns, also known as ionisation zones or spokes, observed, among other discharges, in high power impulse magnetron sputtering discharge (HiPIMS) require non-invasive diagnostics favourable for a precise characterisation of their properties. In this contribution, the single-shot spatial-resolved optical emission spectroscopy of the spoke was conducted in non-reactive HiPIMS discharge using a titanium target. Investigated working pressures cover the conditions with the presence of localised, well-defined spokes. A fast photodiode and a cylindrical Langmuir probe were utilised to capture and determine the passing spoke position. These signals were synchronised with the acquisition of the optical emission spectrum by the intensified charge-coupled device detector. A large amount of single-shot data enabled the statistical analysis of the spoke. The optical emissions of argon atoms and ions and titanium atoms and ions were investigated in the passing spoke. It was found that the intensities of the spectral lines of the Ar and Ti species have the characteristic evolution for all studied spectral lines of this specific species within the spoke. The intensity evolutions are independent of the applied pressure. The evolution of the excitation temperatures determined by the Boltzmann plot method using the Ar II and Ti I and Ti II spectral lines remains constant within the spoke in the margin of standard error for all investigated pressures.