Bulletin of the American Physical Society
72nd Annual Gaseous Electronics Conference
Volume 64, Number 10
Monday–Friday, October 28–November 1 2019; College Station, Texas
Session HW3: Modeling and Simulation II |
Hide Abstracts |
Chair: Aranka Derzsi, West Virginia University Room: Century III |
Wednesday, October 30, 2019 8:00AM - 8:15AM |
HW3.00001: Computational Modeling of Ion Energy and Angular Distributions in Pulsed Source and Bias Plasmas Rochan Upadhyay, Kenta Suzuki, Peter Ventzek, Laxminarayan Raja, Alok Ranjan Accurate predictions of the Ion Energy and Angular Distributions (IEADFs), are essential for a range of critical applications in thin films deposition and etching. Ion generation and flux is determined by ionization rates that depend on reactor-level parameters. Ion energy and angle depends on the acceleration of the ions across the sheath, driven by potential differences governed by the spatial plasma distribution. The IEADF at the wafer surface sensitively depends on rare collisional events such as charge exchange and ion-neutral collisions during the ion's transit across the sheath. Using ion transport parameters computed using standard fluid modeling techniques can significantly misrepresent the actual IEADFs at surfaces. In this study we use a hybrid approach where we employ VizGlow$^{TM}$, a fluid based plasma solver, to simulate a (pulsed) Inductively Coupled Plasma (ICP) source with a (pulsed) RF bias. Then we use VizGrain, a companion particle solver, to compute the IEADFs using the test-particle approach. We study the effect of pressure, pulse width and duty cycle and the staggering of the source and bias pulsing cycles on the IEADFs using Argon plama. We compare the simulation results to measurements of IEADFs on a test plasma platform for validation purposes. [Preview Abstract] |
Wednesday, October 30, 2019 8:15AM - 8:30AM |
HW3.00002: Simulations of sheath-wave interactions controlling low frequency modulation of uniformity in VHF driven plasma sources Toshihiko Iwao, Peter Ventzek, Jianping Zhao, Rochan Upadhyay, Laxminarayan Raja Plasma sources capacitively driven at very high frequencies (VHF, e.g. 100MHz) have attracted much interest for semiconductor device fabrication. These sources have the advantage of high efficiency plasma generation since power couples efficiently with electrons and with lower ion energy loss through sheath acceleration. This is beneficial for processes requiring reduced ion energy, high ion and radical flux. At the same time, spatial variations in plasma density and sheath voltage can arise leading to non-uniformities at the wafer. The root cause of VHF plasma non-uniformity is related to both electromagnetic wave and sheath coupling effects. Unfortunately, most previous plasma fluid models that include electromagnetic wave effects have found it challenging to simulate this physics. Predictive models that can capture these effects are important for plasma properties and their uniformity in industrial systems. We have recently developed approaches that have succeeded in reproducing how VHF power influences plasma uniformity by hybridizing electrostatic and electromagnetic power delivery in a plasma fluid model with no loss of self-consistency. These simulations also demonstrate how low frequency added to VHF impacts uniformity through a sheath-wave interaction mechanism. [Preview Abstract] |
Wednesday, October 30, 2019 8:30AM - 8:45AM |
HW3.00003: Computational Optimization of Plasma Chemistry by Reducing Chemical Species and Reactions in Plasma Models Sathya Ganta, Xiaopu Li, Kallol Bera, Shahid Rauf Simulations of plasma processing chambers are used to quantify the effect of source design and process parameters on the species densities, fluxes and energies. A plasma chemistry mechanism involving a large number of species and reactions results in prohibitively high computational cost. In this study, we develop a systematic methodology for eliminating unimportant species and less impactful reactions from computations in plasma simulations. Our plasma model employs Poisson equation for electric field, continuity equations for species densities and energy equation for electrons. The fluxes and energies of the species to the surface derived from the plasma model determine surface processes. We quantify the impact of each reaction and species on the overall species densities at the end of a simulation using a well-defined cost function. Among the species and reactions, we eliminate those that have negligible qualitative impact on the surface chemistry. We then map the plasma source design and process parameter range for which such elimination is possible. This optimized plasma chemistry enables plasma simulations with complex chemistry to be more practical for deposition and etching processes. [Preview Abstract] |
Wednesday, October 30, 2019 8:45AM - 9:00AM |
HW3.00004: RF Hollow Cathode Discharge Simulation using Electron Monte Carlo - Fluid Plasma Model Kallol Bera, Shahid Rauf Radio-frequency (RF) hollow cathode discharges (HCD) have been used for thin film deposition in the semiconductor industry. Hollow cathode systems typically consist of small hollow cylindrical electrodes electrically connected through a power generator to a larger grounded electrode. The hollow cathode geometry allows hollow cathode effect (HCE) depending on operating condition. In this study, we investigate rf hollow cathode discharge using our plasma model. The plasma model consists of species continuity equations along with electron energy equation. Drift-diffusion approximation is used for charged species fluxes. Electric field is calculated using Poisson equation. The secondary electron emission due to ion impact has been included. Electron Monte Carlo model is used to track the emitted electrons until electron energy becomes lower than threshold value when the electrons become part of fluid electrons. We have explored the effect of gas pressures on plasma density in RF HCD of different hole diameters using our model. We compared the simulation results with experimental data of RF HCD. [Preview Abstract] |
Wednesday, October 30, 2019 9:00AM - 9:30AM |
HW3.00005: Hybrid three-dimensional electromagnetic and plasma simulation Invited Speaker: Edward Hammond Plasma uniformity is critical to plasma-based process chambers, which are often driven by capacitively-coupled RF. However, as the electrode dimension becomes an appreciable fraction of the RF wavelength, the plasma density becomes increasingly non-uniform. This is a three-dimensional problem since the RF propagates in the plane between the electrodes while the electric field perpendicular to this plane determines the plasma characteristics, which affect the propagation of the RF. A computationally-inexpensive model can simulate this RF/plasma interaction. The model represents the transmission of RF within a two-dimensional surface bounded above and below by electrodes. The media between the electrodes are assumed to be linear, but this is not valid where plasma is present. A one-dimensional plasma model is used to calculate the local current-voltage behavior, and a lookup table describes their relationship. Following this approach, the three-dimensional Maxwell equations can be reduced to a Helmholtz equation for the voltage between the electrodes. The model is validated against several sets of experimental data, and it captures the behavior of the plasma distribution. First, the plasma profile in an AKT 60K PECVD chamber (Gen 8.5 size substrate) with an asymmetric 13MHz input is predicted. Also, plasma distributions are simulated for 40MHz RF fed into multiple locations on the electrode. Finally, the model predicts the plasma profile with 60MHz applied to two RF feeds. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700