AVS 66th International Symposium & Exhibition
    Plasma Science and Technology Division Tuesday Sessions
       Session PS-TuM

Paper PS-TuM6
Experiment-Model Comparisons in Capacitively Coupled Plasmas at Moderate Pressures for Argon, Helium and Nitrogen

Tuesday, October 22, 2019, 9:40 am, Room B130

Session: Plasma Diagnostics and Sources I
Presenter: David J. Peterson, North Carolina State University
Authors: D. Peterson, North Carolina State University
T. Koh, Applied Materials, Inc.
T.C. Chua, Applied Materials, Inc.
W. Tian, Applied Materials, Inc.
K. Bera, Applied Materials, Inc.
S. Rauf, Applied Materials, Inc.
P.A. Kraus, Applied Materials, Inc.
S.C. Shannon, North Carolina State University
Correspondent: Click to Email
Discharge parameters including electron density, effective collision frequency, effective electron temperature, voltage & current characteristics and sheath thickness around the probe are measured over different pressures and powers ranging from 0.01-4.0 Torr and 10-100 W in Ar, He and N2 plasmas. Fully floating hairpin resonator probes are used in a parallel plate capacitively coupled radiofrequency (rf) discharge driven at 13.56 MHz with a gap distance of 1 inch. Probe measurements are made in the axial and radial directions. Effective collision frequency is measured using the resonance full width half max. Effective electron temperature can determined from the effective collision frequency through the plasma conductivity equation but must assume an electron energy distribution function (EEDF). Probe sheath thickness is measured using a time resolved measurement system capable of ~5 ns time resolution. High temporal resolution is utilized to measure rf phase resolved electron density and effective collision frequency. Measurements indicate the presence of enhanced ionization rates near the powered sheath edge in the collisional regime. Electron density peaks at the discharge center at lower pressures, <100 mTorr, and begins to shift towards the powered electrode at higher pressures due to a measurable DC self bias that is known to occur for geometrically asymmetric discharges. The influence of axial probe spatial resolution and approaches for providing sufficient probe isolation from ground are discussed. Spatial profiles of plasma parameters along with voltage & current characteristics are compared with 2-dimensional fluid plasma simulation results. Detailed model-experiment comparisons play an important role in understanding plasma chemistry mechanisms for these low temperature plasmas at moderately high pressure. All analysis and data acquisition is done with python scripts which are freely available to the public.