Plasma Cleaner - Thermo Scientific Apreo User's Operation Manual

Plasma Cleaner

The Tools menu / Sample Cleaning item starts the Sample Cleaning
procedure, which is an efficient process for removing very thin
contamination layers, that are typically formed by hydrocarbon
residues remaining on vacuum parts after conventional cleaning or that
could have been transferred into the microscope chamber by a sample.
The plasma cleaner generates free oxygen radicals, that react with
hydrocarbon molecules on the surfaces to form CO, CO
molecules that can be pumped away. It is operated at special vacuum
conditions (~50 Pa) similar to the Low Vacuum mode.
Plasma Cleaner
FIGURE 7-10:
The Sample Cleaning procedure uses settings from the Plasma Cleaning
Alignment (see Chapter 4).
For avoiding typical "weak" contamination artifacts during high resolution
imaging (image darkening), 1-2 minutes of plasma cleaning in combination
with cryo cleaning should be sufficient. When bulky deposition is visible
(mostly on image corners), 5 minutes of plasma cleaning is recommended.

Note
Porous, biological or hydrocarbon based samples cannot typically be viewed
without the presence of contamination artifacts that are caused by presence
of contamination sources within the sample itself even after plasma cleaning.
Sometimes, poor image quality can also be caused by e-beam etching and
re-deposition of etched material.

C a u t i o n !
Using the Plasma Cleaner is not recommended when the VolumeScope ultramicrotome is mounted inside the microscope

chamber!
Remove the VS DBS detector from the chamber (parking position) when the Plasma Cleaner is going to be used!

W A R N I N G !
If the EDS / WDS / EBSD system is mounted, use a 1 mm collimator on the EDS detector and do not exceed 5 minutes
overall procedure duration once a day at most.
Always retract the EDS detector before plasma cleaning!
Avoid leaving sensitive carbon-containing samples (e.g. photo resist) inside the chamber during the Plasma Cleaning
procedure, as they may be etched by the cleaning process.
Any material that can create or release oxide easily (e.g. silver) should not be plasma cleaned.
Only the Au-C resolution tests samples can be left inside the chamber during the Sample Cleaning procedure, but not
very often!
7-34 User Manual
System Options: Plasma Cleaner
, and H O
2 2
C O N F I D E N T I A L – limited rights
Feb 2018 Revision A