Reconstruction of the static magnetic field of a magnetron

Krüger, Dennis M.; Köhn, Kevin; Gallian, Sara; Brinkmann, Ralf Peter

doi:10.1063/1.5024983

Cited by 21 publications

(26 citation statements)

References 8 publications

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“…For a type II unbalanced configuration, a magnetic null point is always present and the far-field dipole moment is dominated by the outer ring of magnets and the dominant electron losses are axial rather than radial. An analytical representation of the assumed field configuration for a cylindrical magnet system consisting of permanent magnets, a central and an annular outer ring magnets, in terms of generalized hyper-geometric function is given by Krüger et al (2018). They demonstrate how these functions can be fitted to experimental data, like those presented in figure 8, with a least square method to achieve a fully analytical field model for a given magnet system.…”

Section: Balanced-unbalanced Magnetron Sputteringmentioning

confidence: 99%

“…where v e,⊥ is the electron speed perpendicular to the magnetic field B. Typical values for r ce in a magnetron sputtering discharge are < 1 mm for thermalized (cold) electrons and up to 20 mm for secondary (hot) electrons (Krüger et al 2018). This means that electrons in the target vicinity have gyration radius that is much smaller than the characteristic size of the confining magnetic field structure, that is the electrons are magnetized.…”

Section: Magnetic Confinementmentioning

confidence: 99%

“…This means that electrons in the target vicinity have gyration radius that is much smaller than the characteristic size of the confining magnetic field structure, that is the electrons are magnetized. As a comparison, ions have a gyration radius r ci of the order of few tens of cm and up to 1 m (Krüger et al 2018), which is larger than the characteristic size of the system, and thus the ions are not magnetized by the relatively weak static magnetic field.…”

Section: Magnetic Confinementmentioning

confidence: 99%

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Physics and technology of magnetron sputtering discharges

Guðmundsson

2020

Plasma Sources Sci. Technol.

356

219

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Magnetron sputtering deposition has become the most widely used technique for deposition of both metallic and compound thin films and is utilized in numerous industrial applications. There has been a continuous development of the magnetron sputtering technology to improve target utilization, increase ionization of the sputtered species, increase deposition rates, and to minimize electrical instabilities such as arcs, as well as to reduce operating cost. The development from the direct current (dc) diode sputter tool to the magnetron sputtering discharge is discussed as well as the various magnetron sputtering discharge configurations. The magnetron sputtering discharge is either operated as a dc or radio frequency discharge, or it is driven by some other periodic waveforms depending on the application. This includes reactive magnetron sputtering which exhibits hysteresis and is often operated with an asymmetric bipolar mid-frequency pulsed waveform. Due to target poisoning the reactive sputter process is inherently unstable and exhibits a strongly non-linear response to variations in operating parameters. Ionized physical vapor deposition was initially achieved by adding a secondary discharge between the cathode target and the substrate and later by applying high power pulses to the cathode target. An overview is given of the operating parameters, the discharge properties and the plasma parameters including particle densities, discharge current composition, electron and ion energy distributions, deposition rate, and ionized flux fraction. The discharge maintenance is discussed including the electron heating processes, the creation and role of secondary electrons and Ohmic heating, and the sputter processes. Furthermore, the role and appearance of instabilities in the discharge operation is discussed.

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Section: Balanced-unbalanced Magnetron Sputteringmentioning

confidence: 99%

Section: Magnetic Confinementmentioning

confidence: 99%

Section: Magnetic Confinementmentioning

confidence: 99%

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Physics and technology of magnetron sputtering discharges

Guðmundsson

2020

Plasma Sources Sci. Technol.

356

219

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“…In this planar circular magnetron configuration, the static magnetic field is arranged in such a way that the electrons drift azimuthally. The magnetic field strength is typically in the range 20-50 mTesla [3], so the electrons are magnetized, while the magnetic field does not influence the ion trajectories directly [5].…”

Section: Introductionmentioning

confidence: 99%

Influence of the magnetic field on the discharge physics of a high power impulse magnetron sputtering discharge

Rudolph¹,

Brenning²,

Hajihoseini³

et al. 2021

J. Phys. D: Appl. Phys.

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The magnetic field is a key feature that distinguishes magnetron sputtering from simple diode sputtering. It effectively increases the residence time of electrons close to the cathode surface and by that increases the energy efficiency of the discharge. This becomes apparent in high power impulse magnetron sputtering (HiPIMS) discharges, as small changes in the magnetic field can result in large variations in the discharge characteristics, notably the peak discharge current and/or the discharge voltage during a pulse. Here, we analyze the influence of the magnetic field on the electron density and temperature, how the discharge voltage is split between the cathode sheath and the ionization region, and the electron heating mechanism in a HiPIMS discharge. We relate the results to the energy efficiency of the discharge and discuss them in terms of the probability of target species ionization. The energy efficiency of the discharge is related to the fraction of pulse power absorbed by the electrons. Ohmic heating of electrons in the ionization region leads to higher energy efficiency than electron energization in the sheath. We find that the electron density and ionization probability of the sputtered species depend largely on the discharge current. The results suggest ways to adjust electron density and electron temperature using the discharge current and the magnetic field, respectively, and how they influence the ionization probability.

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“…The discharge was created using a planar magnetron assembly (Thin Film Consulting IX2U) suitable for round targets with a diameter of 50 mm or 2 . The magnetic field configuration for this magnetron assembly was reconstructed from measurements according to the method of Krüger et al and is shown as part of figure 1(b) [19]. The measurement was performed on a magnetron assembly of the same model (Thin Film Consulting IX2U) using a Hall probe.…”

Section: Chamber and Dischargementioning

confidence: 99%

Velocity distribution of metal ions in the target region of HiPIMS: the role of Coulomb collisions

Held

Thiemann-Monjé

Keudell

et al. 2020

Plasma Sources Sci. Technol.

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High power impulse magnetron sputtering (HiPIMS) discharges have become an important tool for the deposition of thin, hard coatings. Such discharges are operated at a very low working gas pressure in the order of 1 Pa. Therefore, elastic collisions between ions and other heavy particles are often calculated to occur with low frequency, using the hard sphere approximation. However, inside the magnetic trap region of the discharge, a very dense plasma is created and Coulomb collisions become the dominant collision process for ions. In this article, we show that Coulomb collisions are a necessary part of a complete description of ion movement in the magnetic trap region of HiPIMS. To this end, the velocity distribution function (VDF) of chromium and titanium ions is measured using high-resolution optical emission spectroscopy. The VDF of those ions is then described using a simple simulation which employs a direct simulation Monte Carlo scheme. The simulation describes the self-relaxation of the VDF that is initially a Thompson distribution as being created during the sputtering process. Measurement positions inside the discharge are matched to the simulation results choosing an appropriate relaxation time. In this fashion, excellent agreement between simulation and measurement is obtained. We find, that the distribution quickly becomes mostly Maxwellian with a temperature of 9 eV for titanium ions and 4.5 eV in the case of chromium ions. Only the high energy tail of the VDF retains the shape of the initial Thompson distribution. The observed high temperature is explained with an energy redistribution from the highly energetic Thompson distribution into an partly-thermalized Maxwell-like distribution. Finally, the temperature resulting from this energy redistribution is calculated using a simple analytical model which shows good agreement with the measurements.

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Reconstruction of the static magnetic field of a magnetron

Cited by 21 publications

References 8 publications

Physics and technology of magnetron sputtering discharges

Physics and technology of magnetron sputtering discharges

Influence of the magnetic field on the discharge physics of a high power impulse magnetron sputtering discharge

Velocity distribution of metal ions in the target region of HiPIMS: the role of Coulomb collisions

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