| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Friday Sessions |
| Session PS-FrM |
| Session: | Plasma Modeling |
| Presenter: | David J. Peterson, North Carolina State University |
| Authors: | D. Peterson, North Carolina State University S. Shannon, North Carolina State University W. Tian, Applied Materials Inc. P. Kraus, Applied Materials Inc. K. Bera, Applied Materials Inc. S. Rauf, Applied Materials Inc. T. Chua, Applied Materials Inc. T. Koh, Applied Materials Inc. |
| Correspondent: | Click to Email |
Plasma parameters including electron density, effective collision frequency, effective electron temperature, voltage & current characteristics, neutral gas temperature, ion temperature and sheath thickness around the probe are measured over different pressures and powers ranging from 0.1-4.0 Torr and 20-150 W in Ar, He, Ar-He, and N2 plasmas. Both grounded and fully floating hairpin resonator probes are used in a parallel plate capacitively coupled system driven at 27 MHz. Probe measurements are made in the axial and radial directions. Probe sheath thickness is measured using a time resolved measurement system capable of ~100 ns time resolution. 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 requires assuming an electron energy distribution function (EEDF). Effective electron temperatures are presented for three different EEDFs: Maxwellian, Bi-Maxwellian, and Druyvesteyn. Neutral gas temperature is measured by assuming rotational-translational equilibrium in N2 where the second positive system is used to determine rotational temperatures. Ion temperatures are also determined through this method via the 1st negative system in N2+. Spatial profiles of plasma parameters along with voltage & current characteristics are compared with 2-dimensional fluid plasma simulation results. The detailed model-experiment comparison proved useful for improving understanding of plasma chemistry mechanisms in these low temperature plasmas at moderately high pressure. The possibility of inferring plasma potential from comparing floating and grounded probe measurements is discussed as well as the possibility of inferring dissociation fractions in N2 from effective collision frequency. A new technique for manufacturing hairpin probes is discussed, which is capable of producing quality factors ~400. All analysis and data acquisition is done with open source python scripts which are freely available to the public.