Effect of positive pulse voltage in bipolar reactive HiPIMS on crystal structure, microstructure and mechanical properties of CrN films

Batková, Šárka; Čapek, Jiří; Rezek, J.; Čerstvý, R.; Zeman, Petr

doi:10.1016/j.surfcoat.2020.125773

Cited by 31 publications

(20 citation statements)

References 24 publications

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“…In [30], however, the effect of the energy-enhanced ion bombardment was observed during growth of a 1 μm thick (Al, Cr) 2 O 3 insulating film on a conducting and grounded substrate, while no effect was observed for deposition on a 0.5 mm thick insulating sapphire substrate. In all the three works [28][29][30], the floating potential at the substrate position U fl during the positive pulse reached the value close to the applied positive voltage, i.e. U fl ≈ U + .…”

Section: Introductionmentioning

confidence: 91%

“…The effects resulting from the energy-enhanced ion bombardment during bipolar HiPIMS have so far been reported for deposition of Cu [18,24], Ti [12], TiN [14], DLC [17,25,26] and CrAlN films [27]. In addition, a study of the effect of U + on the properties of CrN films with grounded and floating substrates was carried out by Batková et al [28]. A clear effect of the energy-enhanced ion bombardment was observed only in the case of a grounded substrate for U + ∈ [0, 400] V, while for a floating substrate no evidence of energetic ion bombardment was seen.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of bipolar HiPIMS discharges by plasma potential probe measurements

Zanáška

Lundin

Brenning

et al. 2022

Plasma Sources Sci. Technol.

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The plasma potential at a typical substrate position is studied during the positive pulse of a bipolar high-power impulse magnetron sputtering (bipolar HiPIMS) discharge with a Cu target. The goal of the study is to identify suitable conditions for achieving ion acceleration independent on substrate grounding. We find that the time-evolution of the plasma potential during the positive pulse can be separated into several distinct phases, which are highly dependent on the discharge conditions. This includes exploring the influence of the working gas pressure (0.3 – 2 Pa), HiPIMS peak current (10 – 70 A corresponding to 0.5 – 3.5 A/cm2), HiPIMS pulse length (5 – 60 μs) and the amplitude of the positive voltage U+ applied during the positive pulse (0 – 150 V). At low enough pressure, high enough HiPIMS peak current and long enough HiPIMS pulse length, the plasma potential at a typical substrate position is seen to be close to 0 V for a certain time interval (denoted phase B) during the positive pulse. At the same time, spatial mapping of the plasma potential inside the magnetic trap region revealed an elevated value of the plasma potential during phase B. These two plasma potential characteristics are identified as suitable for achieving ion acceleration in the target region. Moreover, by investigating the target current and ion saturation current at the chamber walls, we describe a simple theory linking the value of the plasma potential profile to the ratio of the available target electron current and ion saturation current at the wall.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Dynamics of bipolar HiPIMS discharges by plasma potential probe measurements

Zanáška

Lundin

Brenning

et al. 2022

Plasma Sources Sci. Technol.

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“…In view of these outstanding characteristics, HiPIMS brings opportunities to improve ion bombardment energy on the growing films and in this way to optimize the films structures and properties. To enable the development and optimization of controlling ion energy in HiPIMS, in the last two years, a novel approach by applying a reverse positive pulse right after the main negative HiP-IMS pulse is widely studied, generally named as BP-HiPIMS discharge [12][13][14][15][16][17][18][19]. In fact, the asymmetrically bipolar-pulse discharge mode has been used in the traditional midfrequency magnetron discharge and DCMS discharge to reduce 'target poisoning', which also has an advantage of accelerating ions for deposition [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Plasma flux and energy enhancement in BP-HiPIMS discharge via auxiliary anode and solenoidal coil

Han

Luo

Tang

et al. 2021

Plasma Sources Sci. Technol.

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As an emerging and extraordinary plasma source, the bipolar-pulse high power impulse magnetron sputtering (BP-HiPIMS) has promising prospects and wide industrial applications. In this paper, an effort to optimize the plasma flux and energy in BP-HiPIMS via auxiliary anode and solenoidal coil was made. This novel plasma source contains two types of auxiliary anode voltage (direct current and pulse) and one type of solenoidal coil current (direct current) to synergistically enhance the plasma generation and diffusion by electric field and magnetic field together. Systematic evaluations of discharge characteristics demonstrate that applying auxiliary anode voltage and coil magnetic field effectively contribute to a reduction in delay time of target current onset and increase in peak amplitude of target current, which are beneficial for improving plasma generation and target sputtering. The complex plasma dynamics are diagnosed by Langmuir probe and optical emission spectroscopy, and simulated by particle-in-cell/Monte Carlo collision approach. These comprehensive investigations on plasma parameters demonstrate that the plasma density, emission intensity of the metal ions, substrate current density, and ionization fraction of sputtered target particles have been improved with the increase of coil current. The observations of the increase in excitation temperature T exc of Ar atoms, and more extended high-energy tails in electron energy distribution function curves imply that the plasma can be significantly heated by the auxiliary anode. Combining the simulation results and theoretical model proposed in the last sub-content, the diffusion and transport mechanism of charged-particles in complex electric and magnetic fields are discussed. From the theoretical analysis, the qualitative relation between the plasma density and coil current is well consistent with the measurements of electron density obtained by Langmuir probe. These evidences all support the idea that the plasma flux and energy can be enhanced in BP-HiPIMS discharge via auxiliary anode and solenoidal coil together.

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“…One of our most recent works shows that bipolar-HiPIMS enables an energy-enhanced deposition process of high-quality (high hardness, low coefficient of friction, good wear resistance, good adhesion to the substrate, very low surface roughness, and defect free) hydrogen-free DLC thin films on electrically insulated substrates, without using any substrate bias voltage, adhesion interfacial layer or substrate pre-treatment [23]. However, other studies have shown that, apart from reduced arc-generation probability and enhanced discharge stability, there were no net benefits in the case of bipolar-HiPIMS deposition of non-conductive materials [24] or deposition onto nonconductive or floating substrates [25]. The apparently contradictory results, in terms of the effect of positive target voltage on the film's properties, reported in the literature, could be due to some different deposition conditions and/or deposition systems used (e.g., different pulsing and/or magnetic field configurations).…”

Section: Introductionmentioning

confidence: 99%

Effect of Pulsing Configuration and Magnetic Balance Degree on Mechanical Properties of CrN Coatings Deposited by Bipolar-HiPIMS onto Floating Substrate

et al. 2021

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Despite its great potential for thin films deposition and technological applications, the HiPIMS technology has its own limitations including the control of ion energy and flux towards the substrate when coping with the deposition of electrical insulating films and/or the deposition onto insulating/electrically grounded substrates. The bipolar-HiPIMS has been recently developed as a strategy to accelerate the plasma ions towards a growing film maintained at ground potential. In this work, the benefits of bipolar-HiPIMS deposition onto floating or nonconductive substrates are explored. The effect of bipolar-HIPIMS pulsing configuration, magnetic balance-unbalance degree, and substrate’s condition on plasma characteristics, microstructure evolution, and mechanical properties of CrN coatings was investigated. During the deposition with a balanced magnetron configuration, a significant ion bombardment effect was detected when short negative pulses and relative long positive pulses were used. XRD analysis and AFM observations revealed significant microstructural changes by increasing the positive pulse duration, which results in an increase in hardness from 7.3 to 16.2 GPa, during deposition on grounded substrates, and from 4.9 to 9.4 GPa during the deposition on floating substrates. The discrepancies between the hardness values of the films deposited on floating substrates and those of the films deposited on grounded substrates become smaller/larger when a type I/type II unbalanced magnetron configuration is used. Their hardness ratio was found to be 0.887, in the first case, and 0.393, in the second one. Advanced application-tailored coatings can be deposited onto floating substrates by using the bipolar-HiPIMS technology if short negative pulses, relative long positive pulses together with type I unbalanced magnetron are concomitantly used.

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Effect of positive pulse voltage in bipolar reactive HiPIMS on crystal structure, microstructure and mechanical properties of CrN films

Cited by 31 publications

References 24 publications

Dynamics of bipolar HiPIMS discharges by plasma potential probe measurements

Dynamics of bipolar HiPIMS discharges by plasma potential probe measurements

Plasma flux and energy enhancement in BP-HiPIMS discharge via auxiliary anode and solenoidal coil

Effect of Pulsing Configuration and Magnetic Balance Degree on Mechanical Properties of CrN Coatings Deposited by Bipolar-HiPIMS onto Floating Substrate

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