[labnetwork] Ebeam evaporation - arcing between features

[Geil, Bob]

Thanks everyone for your comments/suggestions last week. In case you're interested,  here<https://chanl.unc.edu/wp-content/uploads/sites/18385/2024/05/BowTie_EBL1.jpg> are some optical images of the structure provided by the user. Additional details about the fabrication are included.  The user is pretty convinced that the issue is not with the EBL process (beam blanking, charging, incomplete development, etc).  We're considering electron deflection magnets, which apparently are offered by the vendor (KJLC).

Best,
  Bob




________________________________
From: Youry Borisenkov <yb2471 at columbia.edu>
Sent: Wednesday, May 22, 2024 10:31 AM
To: Geil, Bob <bob.geil at unc.edu>
Cc: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Ebeam evaporation - arcing between features

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Hi,
What materials is the user trying to deposit?
There is definitely charging happening during ebeam evaporation (my symptoms were bubbles in PMMA resist).
I would recommend switching to thermal evaporation if possible, or lowering the power/rate during the deposition. It could also be caused by contamination in the crucible.
Using magnets around the substrate to deflect electrons from reaching the substrate also showed good results on a small area samples.

Thank you,
Youry

On Tue, May 21, 2024 at 6:44 PM Geil, Bob <bob.geil at unc.edu<mailto:bob.geil at unc.edu>> wrote:
Hello labnetwork,

 I have a user that is fabricating some electrodes and has observed what appears to be arcing between the sharp points of the electrodes. Imagine features like this:  > < where the distance between them is 2um - 8um. The substrate is quartz. Fabrication approach is 1) ebeam lithography 2) ebeam evaporation and 3) lift-off.

After EBL development, the electrode circuit is open, as intended
After evaporation +lift-off, there is a line about few 100nms wide that is shorting the electrodes: >-<
There is not a short between the electrodes with the 8um gap, however, there are some metal lines extending from the two sides:  >-  -<

All of this suggests that arcing is occurring.  Has anyone observed this before and can you suggest ways to get around it?

Thanks,
  Bob


Bob Geil, PhD
Technical Director • CHANL
Dept. of Chemistry • UNC-CH
Chapel Hill, NC




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