XEI Scientific, Inc.
The EVACTRON® Anti-Contaminator and De-Contaminator Updated August 2007
How Evactron® RF Plasma Cleans
Evactron® anticontamination system is for SEM and FIBs, EDX and EDS window cleaning.
An RF Plasma Asher in Electron Microscopes that uses a
low-power, air-plasma inside the specimen chamber to create oxygen
radicals, all surfaces are reactively cleaned of hydrocarbons and
residual oils in-situ. This prevents the coating of scanned areas
with hydrocarbon polymer by the electron beam during SEM focusing or
analytical work (no black squares or
raster lines). It is designed for use microscope technicians with
only simple training. Specimen cleaning by Evactron plasma oxidation
may be done inside the specimen chamber either before or after
examination by the electron beam. In addition to plasma oxidation,
the system allows for SEM-CLEAN nitrogen purge cleaning of the SEM
chamber and vacuum system when the plasma is not on.
This cleaning
process takes place while the SEM chamber is at 0.6 Torr in
rough pumping mode and is of a short duration. (2 - 10 minutes). The plasma cleaning is activated by operator command when needed. When activated the SEM is vented first to partial vacuum and then evacuation recommenced. At the correct pressure air is bled into the plasma source and then the RF plasma is ignited to create
activated oxygen radicals for cleaning. After short time the plasma and air leak are turned off and the system is pumped down to remove the residual oxidation products. The SEM is soon ready for operation.
The
feed gas to the plasma is air that is fed into the chamber through
the exclusive
XEI designed, low-power, RF plasma generator which
maximizes oxygen radical output from air. Air is used because it is
always available, and will not create the explosive conditions in oil
sealed vacuum pumps that pure oxygen could. Argon is not used because
it may accumulate and flood the ion pumps used in many SEMs on their
electron guns.
EVACTRON Oxygen
Radical Source on SEM port
A
Nitrogen purge may be used to complete the cleaning and removes water vapor from the chamber. The Nitrogen
purge function may
be operated separately from the plasma function to suppress
backstreaming from the roughing pumps.
Oxygen
radicals are highly reactive to surface hydrocarbon scum or AMC
(Atmospheric Molecular Contamination). The volatile reaction products
of H2O, CO2, and CO
are easily pumped
away
by the vacuum system. The plasma is confined to the generator region
to minimize the bombardment of surfaces by free electrons or
energetic ions that could cause sputtering or polymerization of the
surface hydrocarbons or damage to sensitive SEM parts. The
low power
of the plasma and its confinement prevents
ion etching and damage
to detector windows and other sensitive surfaces within the SEM
chamber. The system consists of a non-sputtering, glow discharge
generator with a gas and power feed-through on a microscope port, RF
Generator and matching network, vacuum gauging and control electronics.
RF Plasma Cleaning Systems for Electron Microscopes
and High Vacuum Systems
Stops Artifacts and Removes Hydrocarbons and Organics.
SEMS, FIBS and fine film substrates:
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The
EVACTRON®
system quickly cleans the interiors of electron
microscopes including the stages, and specimens. It is an
Anti-Contamination or Decontaminator accessory for electron
microscopes and is used for hydrocarbon and organic contamination
control in vacuum systems. It is used for black square and raster
burn control, stopping oil condensation and drip from X-ray windows,
plasma cleaning of high vacuum systems. It can do remote glow
discharge cleaning, and hydrocarbon removal in vacuum chambers. The
Evactron Decontaminator is a SEM Anti-contaminator or SEM
Anticontaminator for RF Plasma cleaning and RF Plasma Ashing of
vacuum chambers, AMC (Atmospheric Molecular Contamination) removal,
or organic contamination control and removal in any high vacuum
system. It removes Organics as an decontaminator.
EVACTRON System on SEM