| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science Poster Session |
| Presenter: | D. Smithe, Tech-X Corporation |
| Authors: | D. Smithe, Tech-X Corporation R. Bravenec, Tokyo Electron America, Inc. P. Stoltz, Tech-X Corporation C. Roark, Tech-X Corporation M. Funk, Tokyo Electron America, Inc. L. Chen, Tokyo Electron America, Inc. E. Kase, Tech-X Corporation |
| Correspondent: | Click to Email |
Generation and heating of plasmas by microwaves to an overdense state (ω<ωpe), where the waves should be cut off, is not completely understood. We study sheath formation and behavior at the interface between an insulating dielectric and an un-magnetized plasma, using electromagnetic particle-in-cell simulation techniques.1 Various scenarios are of interest here, including both situations in which the plasma is under-dense and over-dense, or transitions from under-dense to over-dense. In the case of over-dense plasma, we look at situations involving incident electromagnetic radiation resulting in field components both parallel and perpendicular to the plasma interface, and are interested in the skin-depth penetration of the waves into the plasma. Of particular interest is the resonance of the EM waves at the location in the sheath where the wave frequency matches the plasma frequency and can serve as the major source of heating of over-dense plasmas2 The simulations include the effects of ionization, and allow us to study the buildup of plasma density associated with ionization in the presence of the large fields of the RF-enhanced sheath. The ionization model is a Monte-Carlo type model, with energy dependant cross-section.3 We are also studying the effects of secondary emission processes from the dielectric interface. For example, copious secondary emission is seen to reduce or even momentarily reverse the sign of the sheath. Our secondary emission model4 was originally designed for metallic emission surfaces, but it being re-engineered to treat secondary emission from dielectric materials. It allows for energy and incident angle dependant yield, and produces a specific energy spectrum of outgoing particles. The overall goal of this work is to develop an analytical or tabular model of the sheath for use in fluid models of plasma.
1 “VORPAL: a versatile plasma simulation code,” C. Nieter and J. R. Cary, J. Comp. Phys., vol. 196, pp. 448–472, 2004.
2 “High energy electron generation in surface-wave-produced plasmas,” Yu M. Aliev, V. Yu Bychenkov, A. V. Maximov, and H. Schluter, Plasma Sources Sci. Tech. 1 (1992) pp. 126-131.
3 Theory and Design of Charged Particle Beams, Martin Reiser, Wiley, New York, 1994.
4 “Probabilistic model for the simulation of secondary electron emission,” M. A. Furman and M. T. F. Pivi, Phys. Rev. ST Accel. Beams 5 (2002).