Electromagnetic simulation of helicon plasma antennas for their electrostatic shield design

Journal Article · Sun May 15 00:00:00 EDT 2016 · Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films

DOI:https://doi.org/10.1116/1.4945001· OSTI ID:22592898

Stratakos, Yorgos; Zeniou, Angelos; Gogolides, Evangelos ^[1]

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1. Institute of Nanoscience and Nanotechnology, National Centre for Scientific Research NCSR “Demokritos,” Aghia Paraskevi, Attiki 15341 (Greece)

A detailed electromagnetic parametric analysis of the helicon antenna (half Nagoya type) is shown at 13.56 MHz using a CST Microwave Studio 2012. The antenna is used to excite plasma inside a dielectric cylinder similar to a commercial reactor. Instead of focusing on the plasma state, the authors focus on the penetration and the three dimensional distribution of electric fields through the dielectric wall. Our aim is to reduce capacitive coupling which produces unwanted longitudinal and radial electric fields. Comparison of the helicon antenna electromagnetic performance under diverse boundary conditions shows that one is allowed to use vacuum simulations without plasma present in the cylinder, or approximate the plasma as a column of gyrotropic material with a tensor dielectric permittivity and with a sheath of a few millimeters in order to qualitatively predict the electric field distribution, thus avoiding a full plasma simulation. This way the analysis of the full problem is much faster and allows an optimal shield design. A detailed study of various shields shows that one can reduce the radial and axial fields by more than 1 order of magnitude compared to the unshielded antenna, while the azimuthal field is reduced only by a factor of 2. Optimal shield design in terms of pitch and spacing of openings is determined. Finally, an experimental proof of concept of the effect of shielding on reduced wall sputtering is provided, by monitoring the roughness created during oxygen plasma etching of an organic polymer.

• OSTI ID: 22592898
• Journal Information: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 34, Issue 3; Other Information: (c) 2016 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANTENNAS
BOUNDARY CONDITIONS
COMPARATIVE EVALUATIONS
DIELECTRIC MATERIALS
DISTRIBUTION
ELECTRIC FIELDS
ETCHING
MHZ RANGE 01-100
MICROWAVE RADIATION
ORGANIC POLYMERS
OXYGEN
PARAMETRIC ANALYSIS
PERMITTIVITY
PITCHES
PLASMA
PLASMA SIMULATION
ROUGHNESS
SHIELDS
THREE-DIMENSIONAL CALCULATIONS
WALLS