[labnetwork] mla150 minimum sample size- seeking advice

[Greg Holloway]

Hello Joanna,

This doesn't directly answer your question, but I wanted to share our
approach for small samples on our MLA150 (pneumatic autofocus). We have
users create a pocket wafer with depth and size matching the sample in
question. The pockets are positioned ~ 10 mm away from the center,
allowing the tool to do the initial focusing in the center on a nice flat
section of the wafer. The user can then move to the small sample position
and run their exposure. Some users even have multiple pockets and run
several samples at a time. It works really nicely, we haven't had any
crashes with this setup, and it allows us to handle sizes in the 3 mm range
which is otherwise impossible with the pneumatic autofocus.

Best,
-Greg

On Thu, Sep 25, 2025 at 10:40 PM Joanna Strongson Bettinger <
joannabettinger at berkeley.edu> wrote:

> Dear Lab Network
>
> We have a Heidelberg mla150 in the UC Berkeley NanoLab. We currently have
> the minimum sample size set to 5mm (using optical autofocus). We
> occasionally have samples in the 5-6mm range that the system won't detect,
> and occasionally have samples just below 5mm (around 4.9mm) that it can't
> detect by definition.
>
> We're exploring the possibility of asking Heidelberg to reduce that
> software limit to 3mm or 4mm, and wanted to see other's experiences.
>
> Have you lowered the sample size requirements, and if so, have you seen
> any additional writehead crashes or other issues? Did you find any issues
> to be due to user error in a shared facility, or were they just caused by
> setting the limit so low?
>
> Thanks
> Joanna
>
> --
> Joanna Bettinger
> She/Her
> Process Engineer
> UC Berkeley Marvell Nanofabrication Laboratory
>
>
>
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