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Browse Prior Art Database

Use of Ultraviolet Light in Charged Particle Systems to Reduce Charging And Contamination

IP.com Disclosure Number: IPCOM000099978D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 79K

Publishing Venue

IBM

Related People

McCord, MA: AUTHOR

Abstract

Disclosed is a method of using ultraviolet light in charged particle systems. The ultraviolet light decomposes organic contaminants in the vacuum system, reducing electron-induced surface contamination. It also reduces charging of insulating surfaces that are exposed to electrons or ions by inducing conductivity on the surfaces and by photoemission of excess electrons.

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This is the abbreviated version, containing approximately 52% of the total text.

Use of Ultraviolet Light in Charged Particle Systems to Reduce Charging And Contamination

       Disclosed is a method of using ultraviolet light in
charged particle systems.  The ultraviolet light decomposes organic
contaminants in the vacuum system, reducing electron-induced surface
contamination. It also reduces charging of insulating surfaces that
are exposed to electrons or ions by inducing conductivity on the
surfaces and by photoemission of excess electrons.

      In electron and ion beam systems, insulators are generally
required to isolate system components that are at different
electrical potentials.  In addition, the workpiece itself must
sometimes be an insulator, either as a bulk as in a glass plate, or a
thin film as in a resist-coated wafer.  Furthermore, insulating
surfaces in the form of contamination layers or dust particles can
deposit on otherwise clean metal surfaces.  The surfaces of these
insulators are subject to charging either from stray charged
particles that are always present in such systems, or from the beam
itself when the insulating surface is the workpiece.  When the
surfaces charge, the electric fields produced interact with the beam
and cause unpredictable shifts in the position of the beam.  This is
a common, well documented problem in both electron beam lithography
and high resolution microscopy.

      Contamination layers can build up on surfaces as a result of
electron-induced deposition of organic molecules that are always
present in a vacuum system.  In microscopy, contamination of the
sample can result in damage to the sample as well as a reduction in
image quality.  This is especially harmful when imaging delicate
integrated circuits or when performing surface microanalysis by auger
or X-ray spectroscopy techniques.  In addition, contamination in the
electron optical column can reduce system performance due to charging
or...