Bulletin of the American Physical Society
76th Annual Gaseous Electronics Conference
Volume 68, Number 9
Monday–Friday, October 9–13, 2023; Michigan League, Ann Arbor, Michigan
Session GR2: Inductively Coupled Plasmas |
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Chair: De-Qi Wen, Department of Computational Mathematics Science and Engineering, Michigan State University Room: Michigan League, Henderson |
Thursday, October 12, 2023 10:00AM - 10:15AM |
GR2.00001: Characterization of fundamental plasma parameters in a double inductively coupled plasma: simulation and experiment Katharina Noesges, Jonathan Jenderny, Henrik Hylla, Dominik Filla, Ihor Korolov, Peter Awakowicz, Andrew R. Gibson, Thomas Mussenbrock A double inductively coupled plasma (DICP) setup is used explicitly in biomedical applications, such as sterilizing microorganisms on large-scale objects. For this purpose, a homogeneous plasma process is required. Hence a spatially resolved characterization of the relevant discharge parameters becomes increasingly essential. This work studies a DICP computationally and compares it to experimental results at the same discharge conditions (f = 13.56 MHz, 100 sccm Ar/O$_2$). The Hybrid Plasma Equipment Model (HPEM) developed by M. Kushner was used for the simulation. The experiment uses multipole resonance probe, optical emission spectroscopy, and tuneable diode laser absorption spectroscopy measurements for the characterization. Parameters like power (50 - 800W), pressure (2 - 20 Pa), and argon/oxygen gas mixture (98/2 - 80/20) are varied, and their influence on the discharge is compared. The focus is on radial profiles such as electron densities and temperatures. It is found that the absolute values and the spatial evolution of experimental and simulated data are in good agreement. In addition, HPEM gives insights into the two-dimensional resolution of the power deposition as well as into the capacitive and inductive coupling of the coils. Furthermore, the radial distribution of reactive species like oxygen, which are necessary for biomedical applications, can be investigated. |
Thursday, October 12, 2023 10:15AM - 10:30AM |
GR2.00002: Investigations of Pulse-to-Pulse Instabilities and Abnormal Electron Growth in Highly Electronegative Inductively Coupled Plasmas Tugba Piskin, Evan Litch, Hyunjae Lee, Sang Ki Nam, Mark Kushner Electronegative pulsed inductively coupled plasmas (ICPs) are commonly used for surface modification in microelectronic fabrication. Pulsed ICPs are prone to E-H transitions, which depend on reactor geometry, power pulse profile, pressure, and gas mixture. E-H transitions in ICPs sustained in Ar/Cl2 mixtures were computationally investigated using the Hybrid Plasma Equipment Model (HPEM). The E-mode is particularly strong due to a decrease in electron density resulting from thermal attachment during the interpulse afterglow. During these simulations (base case: 30 mTorr, pulse repetition frequency 13.33 kHz, 30% duty cycle, 350 W average power), startup instabilities causing anomalous electron growth during the E-H transitions were observed for various operating conditions—mostly with large Cl2 mole fractions. We found that the instabilities are pulse periodic and pulse-to-pulse patterns (anomalous or normal growth of electron density) vary with the operating conditions. We will discuss results from the computational investigation for instabilities occuring at the onset of the power pulse and pulse-to-pulse patterns for various operating conditions, including the substrate bias. The correlation between the instability and electron energy-dependent attachment reactions will be discussed. The fluxes, energy, and angle distributions of charged particles to the wafer and dielectric window will be discussed. |
Thursday, October 12, 2023 10:30AM - 10:45AM |
GR2.00003: Modeling of non-equilibrium effects in inductively coupled plasma discharges Sanjeev Kumar, Alessandro Munafo, Sung Min Jo, Marco Panesi The extreme heat loads imposed on a thermal protection shield during hypersonic re-entry are often reproduced by placing a sample of a thermal protection material in a hot jet of plasma. An important class of plasma wind tunnels is the ICP (inductively coupled plasma) facility which offers a large volume of contamination-free plasma for a considerable amount of time as it does not require electrodes to generate the plasma. An important aspect in the modeling of ICPs is the possible impact of Non-Local Thermodynamic Equilibrium (NLTE) effects. Most of the ICP studies reported in the literature assume that LTE conditions prevail. This assumption, however, breaks down at low pressures due to lowering of collisional rates among gas particles. Under these circumstances, the availability of accurate NLTE kinetics models is of paramount importance. |
Thursday, October 12, 2023 10:45AM - 11:00AM |
GR2.00004: Unraveling the Influence of Non-Maxwellian Electron Energy Distribution on Argon Inductively Coupled Plasma Maryam Khaji, Sanjeev Kumar, Alessandro Munafo, Alessandro Parente, Marco Panesi The objective of this work is to develop a self-consistent model for an inductively coupled radio frequency argon plasma. Inductively coupled plasma (ICP) torches are known to exhibit a high degree of non-equilibrium at low and moderate pressures, resulting in situations where the electron temperature is significantly higher than the gas temperature. This leads to a substantial deviation of the electron energy distribution function (EEDF) from the Maxwellian form and a drastic change in the electron coefficients. To accurately simulate this non-equilibrium behavior in fluid model simulations, the variation in the electron coefficients needs to be considered, which can be determined by solving the electron Boltzmann equation (BE) using collision cross-sections. In this work, the in-house magneto-hydrodynamic model is coupled with a BE solver to investigate the degree of departure from local thermodynamic equilibrium. A step-by-step approach is adopted, starting with 0D cases and comparing results between our in-house codes coupled with the Boltzmann solver and another software called ZDPlasKin. Once verified, the next step involves coupling our in-house 1D CFD solver with the Boltzmann solver, showing good agreement in the results. The common factor in all test cases is the presence of conditions leading to a high degree of ionization. The subsequent simulations will focus on the conditions of the CHESS plasmatron exhibiting low ionization degrees. Additionally, future work aims to enrich the chemistry model for a more realistic representation of the ongoing chemical processes in highly non-equilibrium conditions of ICPs. |
Thursday, October 12, 2023 11:00AM - 11:15AM |
GR2.00005: Simulation of Inductively Coupled Plasmas Using a Direct Implicit Darwin 2D Particle-in-Cell Code Dmytro Sydorenko, Alexander V Khrabrov, Andrew Tasman T Powis, Willca Villafana, Igor D Kaganovich, Sierra Jubin, Stephane A Ethier A 2D electromagnetic particle-in-cell code has been developed which calculates the electrostatic field using the direct implicit algorithm and the solenoidal electric field and magnetic field using the Darwin algorithm. The code uses Cartesian geometry and allows to place metal and dielectric objects inside the simulation domain. The cell size of the numerical grid may exceed the Debye length, the time step may exceed the period of electron Langmuir oscillations. Since the Darwin scheme is used, there is no restrictions on the time step due to the light wave propagation. The electrostatic part of the code is similar to [1]. The Darwin scheme is implemented using a new approach based on the vorticity equation for the solenoidal electric field. The code includes a Monte-Carlo model of electron neutral collisions, electron emission from material surfaces, charge exchange collisions, and abundant diagnostics. The code is used to simulate a top-coil inductively coupled plasma device with realistic dimensions. Simulation demonstrates that the plasma is sustained by the induced solenoidal electric field. With coarse grids and large time steps, the numerical cost of the implicit simulation is relatively low and a quasi-steady state can be achieved significantly faster than in an explicit simulation which resolves all the plasma scales. |
Thursday, October 12, 2023 11:15AM - 11:30AM |
GR2.00006: A Plasma-Based Frequency-Selective Limiting Reflectarray Krushna Kanth Varikuntla, Abbas Semnani High-power microwaves can disrupt communication frequencies and cause extensive damage to electronic equipment. Therefore, it is crucial to shield sensitive equipment from incoming high-power waves. Frequency-selective surfaces (FSS) are planar periodic arrays that exhibit selective filtering responses. Various architectures have been proposed to implement these surfaces for protection applications in recent years. However, many of these structures rely on active elements such as PIN and Schottky diodes, which suffer from limitations such as low power handling, wide bandwidth, and poor selectivity. |
Thursday, October 12, 2023 11:30AM - 12:00PM |
GR2.00007: Reactive species production within inductively coupled hydrogen plasmas Invited Speaker: James Dedrick Non-equilibrium plasmas containing hydrogen are of significant interest for basic plasma physics and technological applications including the plasma-assisted processing of semiconductors. Obtaining enhanced spatial control of reactive species production, including that for negative ions at atomic hydrogen, is critical. In this talk, we report upon recent investigations of hydrogen containing, low-pressure inductively coupled plasmas from experimental and simulation perspectives. Mass spectrometry and photoemission yield spectroscopy are applied to investigate the surface production of negative ions from electrically biased doped diamond, and laser spectroscopy enables the measurement of atomic hydrogen across the plasma. Fluid-kinetic simulations, which track the reaction kinetics of 14 vibrationally excited states of the hydrogen molecule while incorporating heavy-particle reaction enthalpies and self-consistent gas heating, are used to study the impact of spatial gradients in the rf power and gas temperature on the formation of atomic hydrogen. The results are expected to be of interest for developing a detailed understanding of the physics of reactive-species production, and the application of the underpinning mechanisms to technological applications. |
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