AVS 46th International Symposium
    Plasma Science and Technology Division Friday Sessions
       Session PS-FrM

Paper PS-FrM9
Plasma Injection with Small Helicon Sources

Friday, October 29, 1999, 11:00 am, Room 609

Session: Emerging Plasma Applications
Presenter: F.F. Chen, University of California, Los Angeles
Authors: F.F. Chen, University of California, Los Angeles
X. Jiang, Broadcom, Inc.
Correspondent: Click to Email
Distributed plasma sources for large-area etching and deposition, comprising multiple helicon injectors, have been shown to be feasible.@footnote 1@ In this experiment, we studied the coverage provided by a single small source, varying the magnetic field and antenna configurations. The source was a 2.2 cm i.d., 12 cm long pyrex tube tightly covered by a thin, 3.9 cm i.d. solenoidal magnet coil providing up to a B = 100G field. A helical antenna was normally used to launch right-hand circularly polarized waves with 0-1000 W of 13.56 or 27.12 MHz power. The argon plasma was injected into to a 30 cm diam chamber with or without a permanent magnet "bucket". The low-field density peak@footnote 2@ usually found in helicon sources was not seen; instead, the maximum density almost always occurred at B = 0, as in ordinary ICPs. However, the densities were in the 10@super 11-12@ cm@super -3@ range characteristic of helicon sources. These were indeed helicon discharges, and the absence of a low-field peak was explained by detailed mapping of the magnetic field. With close-fitted solenoids, the plasma created near the edge of the source was scraped off by the entrance flange or was brought back to the top plate once the magnetic field became strong enough to entrain the electrons. At the higher fields, only the plasma created near the axis was available to a downstream probe. The high efficiency of helicon sources can be made available by properly designing the magnetic field coils so that all the field lines reach the interior of the downstream region and then diverge before striking the substrate. @FootnoteText@ @footnote 1@F.F. Chen and J.D. Evans, Proc. Plasma Etch Users Group (NCCAVS, 150 W. Iowa Ave., Suite 104, Sunnyvale, CA 94086) (1998). @footnote 2@F.F. Chen, J. Vac. Sci. Technol. A 10, 1389 (1992). .