Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session FR1: Magnetron Plasmas |
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Chair: Yevgeny Raitses, PPPL Room: Sendai International Center Shirakashi 1 |
Thursday, October 6, 2022 8:00AM - 8:30AM |
FR1.00001: Electron power absorption in magnetron sputtering discharges Invited Speaker: Bocong Zheng We demonstrate a self-consistent and complete description of electron power absorption in magnetron sputtering discharges. The electron energization in radio frequency magnetron sputtering (RFMS), direct current magnetron sputtering (DCMS), and high power impulse magnetron sputtering (HiPIMS) discharges is studied via fully kinetic 1d3v/2d3v particle-in-cell/Monte Carlo collision (PIC/MCC) simulations. Some primary electron energization mechanisms are identified in these discharges, and their transition modes are observed. In RFMS discharges, the electron power absorption can be primarily decoupled into the positive Ohmic power absorption in the bulk plasma region and the negative pressure-induced power absorption near the target surface. Ohmic power absorption is the dominant electron power absorption mechanism, mostly contributed by the azimuthal electron current. The contribution of secondary electrons is negligible under typical RFMS discharge conditions. In DCMS discharges, however, secondary electrons are necessary to maintain the discharge. Scale-invariant breathing oscillations are observed in similar DC magnetron discharges and microdischarges. With the onset and development of breathing oscillations, the electron energization mechanism shifts from sheath energization to Ohmic heating in the ionization region. During the discharge runaway phase in HiPIMS discharges, i.e., the transition from the low-current DCMS regime to the high-current HiPIMS regime, metal ions gradually replace gas ions as the dominant, the sheath width decreases drastically with the increase in plasma density, and the electron energization transforms from sheath energization to Ohmic heating. These results are beneficial for the design, optimization, and scaling of magnetron sputtering discharges under various power sources in practical applications. |
Thursday, October 6, 2022 8:30AM - 8:45AM |
FR1.00002: Modeling of high power impulse magnetron sputtering (HiPIMS) discharges with graphite target Henrik Eliasson, Martin Rudolph, Kateryna Barynova, Nils Brenning, Michael A Raadu, Hamidreza Hajihoseini, Tiberiu M Minea, Daniel Lundin, Jon T Gudmundsson High ionization fraction of carbon is essential when depositing tetrahedral amorphous carbon (ta-C) or diamond like carbon (DLC) thin films as energetic ion bombardment promotes the formation of films with high sp3 content. The deposition of DLC films by high power impulse magnetron sputtering (HiPIMS) has been explored extensively, but the ionization fraction of the carbon appears to be low. Here, the ionization region model (IRM) [1] is applied to model a HiPIMS discharge in argon with a graphite target. The discharge develops into working gas recycling, 90 % of the discharge current at the cathode target surface composed of Ar+ ions, while the contribution of the C+ ions is below 5 %, even for peak current densities as high as 3 A/cm2 [2]. This is due to a combination of four mechanisms: a high ionization energy, a small ionization cross section, a short residence time of sputtered carbon in the ionization region, and a high ion back-attraction probability. This insight suggests promising handles for fine-tuning of the process. We explore how the addition of neon to the working gas influences the operating parameters. |
Thursday, October 6, 2022 8:45AM - 9:00AM |
FR1.00003: Study of ac magnetically enhanced capacitively coupled plasma argon discharges using particle-in-cell simulations Kaviya Aranganadin, Guoning Wang, Hua-Yi Hsu, John P. Verboncoeur, Ming-Chieh Lin Magnetically enhanced capacitively coupled plasma (CCP) sources such as magnetically enhanced reactive ion etching (MERIE) reactors have been developed for the high plasma density etching and sputtering of materials for microelectronics fabrication. In a typical MERIE reactor, a static or dc magnetic field is applied parallel to the electrodes to increase the plasma density by trapping more electrons, similar to the mechanism of magnetron sputtering. The operating gas pressure is at tens to hundreds mTorr and the radio frequency (RF) excitation is driven from a few to tens MHz. In this work, an ac magnetically enhanced CCP or MERIE is constructed by applying a transverse ac magnetic field to the low-pressure RF CCP argon discharge. The effects of time-varying magnetic field on the plasma density enhancement and electron energy distribution function (EEDF) are investigated and compared to those of a static or dc magnetic field. The simulations have been conducted with a modified version of the particle-in-cell Monte Carlo collision (PIC-MCC) code, XPDP1, developed by Plasma Theory and Simulation Group (PTSG) formerly at UC Berkeley now at Michigan State University which is a bounded electrostatic code for simulating 1-D plasma devices. The PIC-MCC simulation results show that the enhancement of plasma density by ac magnetic fields could be comparable with while lower than that by a static magnetic field at normal operating pressures. However, the time-varying magnetic field is most effective when its frequency is resonant with that of the applied RF field. In addition, it is found that the ac magnetic field exhibits a higher enhancement than the static one in the lower pressure regime and this crossover can be understood with the analysis of EEDF which provides more physical insight. |
Thursday, October 6, 2022 9:00AM - 9:15AM |
FR1.00004: Electron energization via ExB drift generation in rf magnetrons operated at a low pressure Denis Eremin, Birk Berger, Jens Kallähn, Kevin Köhn, Dennis Krueger, Liang Xu, Peter Awakowicz, Julian Schulze, Ralf Peter Brinkmann Sputtering via rf magnetrons is an important film deposition technology used |
Thursday, October 6, 2022 9:15AM - 9:30AM |
FR1.00005: Formation and sustainment of spokes in planar dc magnetrons Denis Eremin, Liang Xu, Jens Kallaehn, Kevin Koehn, Dennis Krueger, Ralf Peter Brinkmann Planar dc magnetrons with a conducting target are often used as an essential part of the film |
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