Bulletin of the American Physical Society
70th Annual Gaseous Electronics Conference
Volume 62, Number 10
Monday–Friday, November 6–10, 2017; Pittsburgh, Pennsylvania
Session QR1: Magnetically Enhanced Plasmas I |
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Chair: Pascal Chabert, LPP, Ecole Polytechnique Room: Salon D |
Thursday, November 9, 2017 8:00AM - 8:15AM |
QR1.00001: The role of recycling in pulsed sputtering magnetrons Jon Tomas Gudmundsson, Daniel Lundin, Michael A. Raadu, Nils Brenning In high power impulse magnetron sputtering (HiPIMS), high power is applied to the magnetron target (cathode) in unipolar pulses at low duty cycle. This results in a high plasma density (electron density) and a high ionization fraction of the sputtered material. The time-dependent plasma discharge ionization region model (IRM) allows us to explore the temporal variation of the various parameters of the discharge process. Here we use the model to explore both non-reactive and reactive discharges. For high currents the discharge with Al target develops almost pure self-sputter recycling, while the discharge with Ti target exhibits close to a 50/50 combination of self-sputter recycling and working gas-recycling [1]. For a reactive operation we find that when the discharge is operated in the metal mode Ar$^+$ and Ti$^+$-ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar$^+$-ions contribute almost solely to the discharge current [2]. In the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. [1] C. Huo et al., J. Phys. D: Appl. Phys. (submitted 2017). [2] J. T. Gudmundsson et al. Plasma Sources Sci. Technol. 25, 065004 (2016). [Preview Abstract] |
Thursday, November 9, 2017 8:15AM - 8:30AM |
QR1.00002: Pressure dependence of Ar$_{\mathrm{2}}^{\mathrm{+}}$, ArTi$^{\mathrm{+}}$, and Ti$_{\mathrm{2}}^{\mathrm{+}}$ dimer formation in a magnetron sputtering discharge. Martin Cada, Rainer Hippler, Vitezslav Stranak, Zdenek Hubicka, Christiane Helm Formation of Ar$^{\mathrm{+}}$ and Ti$^{\mathrm{+}}$ monomer and of Ar$_{\mathrm{2}}^{\mathrm{+}}$, ArTi$^{\mathrm{+}}$, and Ti$_{\mathrm{2}}^{\mathrm{+}}$ dimer ions in a magnetron sputtering discharge with a Ti cathode and in an argon atmosphere was investigated by means of energy-resolved mass spectrometry. Energy spectra of Ar$^{\mathrm{+}}$ and Ti$^{\mathrm{+}}$ ions show distinct features which are related to the specific formation processes taking place in the plasma region and during ion bombardment of the Ti cathode. Our observations proved that low-energy Ar$^{\mathrm{+}}$ ions are produced inside the plasma region. Ti$^{\mathrm{+}}$ ions originate from sputtering events. The measured energy distribution of titanium ions does not follow Thompson's formula, however. At the lowest gas pressure the measured energy distribution can be modelled by a shifted Maxwellian distribution. Formation of Ar$_{\mathrm{2}}^{\mathrm{+}}$, ArTi$^{\mathrm{+}}$, and Ti$_{\mathrm{2}}^{\mathrm{+}}$ dimer ions show pronounced pressure dependencies which are attributed to various formation and loss processes. [Preview Abstract] |
Thursday, November 9, 2017 8:30AM - 8:45AM |
QR1.00003: Low-frequency ionization oscillations due to azimuthally rotating spokes in cross-field configurations Kentaro Hara, Rei Kawashima Rotating spokes are self-organizing coherent structures observed in magnetron discharge, Penning discharge, and Hall effect thrusters. The unique feature about the rotating spokes is that the oscillations are in the kHz range, i.e., low frequency compared to the electron dynamics due to the ExB drift. This indicates that the rotating spokes are ionization oscillations due to interaction between neutral atoms, ions, and electrons. A two-dimensional (axial-azimuthal) hybrid kinetic-fluid model is used to model the discharge plasma in a Hall effect thruster. It has been reported that the potential solver assuming a drift-diffusion approximation with the current balance equation introduces an ill-conditioned matrix, which is difficult to solve. A pseudo-time stepping method in which the diffusion equation is solved in a time-advanced fashion enables stable calculation of the potential solver. The low-frequency rotating spokes obtained from the hybrid simulation show qualitative agreement with published experimental data. The local dispersion relation of gradient drift waves indicates that the instability occurs in the downstream of the discharge plasma, and the simulation results agree with the phase velocity obtained from theory. [Preview Abstract] |
Thursday, November 9, 2017 8:45AM - 9:00AM |
QR1.00004: Plasma Diagnostics in Reactive High Power Impulse Magnetron Sputtering System. Zdenek Hubicka, Jiri Olejnicek, Martin Cada, Petra Ksirova, Stepan Kment Plasma parameters in the reactive pulsed magnetron (R-HIPIMS) were investigated during films deposition. Parameters of Ar$+$H2S and Ar$+$O2 pulsed plasma were investigated by the emission spectroscopy, Langmuir probe, RF ion flux and impedance probes. Ionized fraction of sputtered particles and deposition rate were measured by the modified QCM with a magnetic filter and biased electrode. Different modes of reactive deposition process were found and described by physical model. This R-HIPIMS system was used for the deposition of semiconducting oxide and sulphide thin films. These semiconducting films were optimized for applications in solar water splitting solar cells. Oxide thin films such as Fe2O3 and TiO2 films were deposited on FTO glass and Pt coated silicon substrates by R-HIPIMS in Ar$+$O2 gas mixture using target made of Fe and Ti, respectively. Photoelectrochemical performance of these films was investigated for various conditions and postdeposition annealing. Sulphide semiconductor FeS2 films were deposited by R-HIPIMS in gas mixture of Ar$+$H2S and pure Fe target. Photoelectrochemical properties of these films were examined in dependence on plasma parameters and postdeposition annealing in H$_{\mathrm{2}}$S$_{\mathrm{\thinspace }}$low pressure plasma. [Preview Abstract] |
Thursday, November 9, 2017 9:00AM - 9:15AM |
QR1.00005: ABSTRACT WITHDRAWN |
Thursday, November 9, 2017 9:15AM - 9:30AM |
QR1.00006: Outer Ring-Shaped Magnetized Plasma by RF and HiPIMS Source Hossain Md. Amzad, Yasunori Ohtsu We have proposed a magnetized outer ring-shaped plasma sputtering source with a concentrically monopole arrangement of magnets with each gap of $R \quad =$ 5 mm for specific target area utilization by radio frequency (RF) and high power impulse magnetron sputtering (HiPIMS). The three setups are investigated such as with a center magnet with case (a): magnet arrangement with three circles, case (b): magnet arrangement with two circles, and case (c): magnet arrangement with one circle from the point of view of specific outer area target utilization. In the experiments, Ar gas of 12.0 [Pa], RF power of 50100 [W] at 13.56 [MHz] for RF discharge and Ar gas of 12.0 [Pa], target voltage of 6001000 [V] at 2.5 [kHz] and pulse width of 20 $\mu $s for HiPIMS source are used to produce the plasma. 2D magnetic field map shows that the magnetic flux density in component transverse to the target surface has a peak density the exterior circle of magnet arrangement for all setups. Ring-shaped plasma in the specific target outer area is observed for both RF and HiPIMS discharge where the transverse component of magnetic flux is sufficiently high and its diameter depends on a number of magnets on the circles. The experimental results are summarized based on the radial profile of ion saturation current, plasma density and the typical discharges between RF and HiPIMS source. [Preview Abstract] |
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