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Compact High-Density Radical Generator

IP.com Disclosure Number: IPCOM000106324D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 86K

Publishing Venue

IBM

Related People

Holber, WM: AUTHOR [+2]

Abstract

Disclosed is an inexpensive and compact device which generates high densities of atomic and molecular radicals. The high efficiency of the radical generation is obtained by internally tuning a resonant inductive coil which surrounds a cylindrical plasma chamber. Radicals produced by the electron impact dissociation of the feed gas diffuse from the plasma chamber and may be used for surface treatments and reactive-gas modification of sputtered, evaporated, or ablated thin films.

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Compact High-Density Radical Generator

      Disclosed is an inexpensive and compact device which generates
high densities of atomic and molecular radicals.  The high efficiency
of the radical generation is obtained by internally tuning a resonant
inductive coil which surrounds a cylindrical plasma chamber.
Radicals produced by the electron impact dissociation of the feed gas
diffuse from the plasma chamber and may be used for surface
treatments and reactive-gas modification of sputtered, evaporated, or
ablated thin films.

      A source of gaseous radicals and active species is frequently
needed for many vacuum processes.  For example, halogen radicals or
oxygen radicals can be used to clean surfaces or alter the chemistry
of surfaces to improve adhesion.  The physical space available for
such a radical source is sometimes limited and therefore it is
important that the device be compact.  In addition, the need for
purity demands an ultrahigh vacuum (UHV) compatible device.  Although
some devices for the generation of radicals are currently available
[1-3], their performance is not optimized.  Too few radicals are
generated or the source contributes contamination to the process.
The following describes a device which generates gaseous radicals
with high density, low contamination, and in a compact enclosure.

      The radical generator is shown in the Figure.  A plasma is
generated in an alumina tube by inductively coupling radio frequency
(rf) energy into the feed gas using a helical coil.  This method of
inductive coupling is not unique but the method of tuning used here
gives significantly improved performance.

      The coil used for inductive coupling to a plasma must be
matched to an rf power source using a tuning network.  This network
consists of capacitors and inducto...