22nd International Symposium on Plasma Chemistry
July 5-10, 2015; Antwerp, Belgium
Using a commercial tool for modeling an argon plasma on the MVP (microwave
sheath-voltage plasma)
L. Alberts1, S. Kar2 and H. Kousaka2
1
2
at home, [email protected]
Nagoya University, Department of Mechanical Science and Engineering, Japan
Abstract: The MVP plasma system is an interesting device for very high-rate PECVD
combining a DC sheath with microwave surface waves. A fluid modeling using
commercial packages reproduces the plasma production in interaction with the electrical
fields. Further physical descriptions need to be implemented for an accurate description of
the MVP Plasma, but the results can help the technical design of new plasma sources.
Keywords: PECVD, microwave, plasma modeling
1. Introduction
In the coating business a possible paradigm shift is
opened by the very high deposition rates achieved by
high-density plasma CVD [1-3]. Instead of building ever
bigger batch coating machines with their increasingly
inflexible handling and intensive capital cost, new
part-2-part coatings at high frequency (process time less
than 3 minutes) will be a gain in flexibility and
competitivity.
The designing of dedicated process
chambers for each type of part to be coated needs the help
of simulation tools.
The MVP system allowing
diamond-like-carbon depositions with more than
100 µm/hr [4] uses a dual frequency plasma excitation in
the extreme range: 0 (DC) and 2.45 GHz. The plasma
description needs a simultaneous solving of
high-frequency electromagnetics and almost static electric
potential. The fine tuning of the chemical reactions
influences a lot the simulation validity. An easy fluid
model may be satisfactory for the plasma distribution
forecast in the design task of new PECVD reactors.
2. Experimental
The Comsol Multiphysics package allows a fluid
modeling of surface wave sustained plasmas [5]. With the
plasma and rf modules of the actual Comsol Multiphysics
package the set up of an Argon plasma modeling has been
simplified and adds the description of a DC sheath [6, 7].
The computing was done on a standard PC with 16 GB
Ram and a 3 GHz i7 processor within one to 50 hours
depending on settings. Real description of the plasma has
been published [8, 9] for comparison.
3. Results
All behaviours of a real plasma can be observed by the
modeling. Especially the close interaction of plasma
density with the electromagnetic fields can be followed.
The reaching of the plasma density levels above the
plasma frequency modifies the microwave penetration
behaviour into the plasma and allows the MVP type of
plasma structure where a high-density plasma is following
P-I-2-41
the substrate surface depending on the total microwave
power coupled into the vessel [10].
The plasma chemistry description of the MVP case with
the combination of a high-frequency plasma and the DC
sheath is difficult since one would prefer a Townsend
description of the collision cross-sections [11] rather than
the classical reaction rate used for microwave plasmas
[12]. Also the very details on transient heating at the
plasma cut-off limit induced by electric field resonance is
unclear [13]. An implementation through an 'effective
collision frequency' is attempted [14]. The precise
physical mechanism is probably not achievable by fluid
modeling but with PIC codes [15].
Nevertheless linear extended MVP plasmas can be
designed with the help of this basic modeling also in their
dual feed-in technique [16].
4. Conclusion
We report on first qualitative agreements of the
modeling of a Microwave Sheath-Voltage combined
Plasma using a commercial multi-physics tool. The
results are considered as sufficient to design reactors for a
part-2-part coating equipment with high throughput which
may allow affordable PECVD coatings for small series of
parts, enabling a broader application of surface coating
technologies to small and medium sized companies.
5. Acknowledgements
This work was supported partly by DAIKO Foundation
research fellowship programme in FY2014 and a Grant
for Advanced Industrial Technology Development
(No. 11B06004d) in 2011 from the New Energy and
Industrial Technology Development Organization
(NEDO) of Japan.
1
Fig. 1. Time evolution of electron density (log-scale) in a MVP system
(the white contour equals ( ne = ncutoff ) (Ar, 50 Pa, -200 V, 10 W).
6. References
[1] Y. Takaoka, H. Kousaka, and N. Umehara. in: Proc.
PSE2012. OR1807 (2012)
[2] S. Merli, A. Schulz, M. Walker, U. Stroth and
T. Hirth. Vakuum in Forschung und Praxis, 25(2),
33 (2013)
[3] R. Dreher, K.-D. Nauenburg, R. Emmerich and
R. Braeuning. in: Proc. 19th Int. Symp. On Plasma
http://www.ispcChemistry – ISPC 2009.
conference.org/ispcproc/ispc19/803.pdf (2009)
[4] H. Kousaka, Y. Takaoka, and N. Umehara. Procedia
Engng., 68, 544-549 (2013)
[5] C. Hunyar, et al. in: Proc. IEEE 35th Int. Conf. on
Plasma Science - ICOPS. (2008)
[6] www.comsol.com /community/exchange/213
[7] www.comsol.com/blogs/microwave-plasmas/
[8] H. Kousaka and N. Umehara. Vacuum, 80, 806
(2006)
[9] S. Kar, L. Alberts and H. Kousaka. AIP Advances,
5, 017104 (2015)
[10] www.researchgate.net/publication/262731943_Nitro
gen-MVP_plasma
[11] G. Hagelaar and L.-C. Pitchford. Plasma Sources
Sci. Technol., 14, 722-733 (2005)
[12] L.L. Alves, S. Letout and C. Boisse-Laporte. Phys.
Rev. E, 79, 016403 (2009)
[13] O. Boudreault, S. Mattei, L. Stafford, J. Margot and
M. Moisan. Phys. Rev. E, 86, 015402(R) (2012)
[14] G. Hagelaar, K. Makasheva, L. Garrigues and J.P. Boeuf. J. Phys. D: Appl. Phys., 42, 194019
(2009)
[15] L.J. Zhu, Z.Q. Chen, Z.X. Yin, G.D. Wang,
G.Q. Xia, Y.L. Hu, X.L. Zheng, M.R. Zhou,
M. Chen and M.H. Liu. Chin, Phys. Lett., 31,
035203 (2014)
2
[16] L. Alberts, M. Kaiser, C. Hunyar, M. Graf,
K. Nauenburg and E. Rauchle. in: Proc. IEEE 35th
Int. Conf. on Plasma Science - ICOPS. (2008)
P-I-2-41