[labnetwork] mla150 minimum sample size- seeking advice

[Greg Allion]

Hi Joanna,
Our uPG 101 allows us to manually focus the write head.  Some really small
samples we had were smaller than the opening in the write head that it uses
for the pneumatic focus, so they would just go straight up through the hole
in the end of the write head.  Obviously be very careful here.  Step
the write head down slowly.  Sample must be flat and fixed focus must be
used as well.
Heidelberg probably wouldn't be thrilled about this, but there wasn't
anything in the software on our system that would prevent it.  The 101 may
be a bit different, but it does expose with stripes as opposed to the 501,
so probably pretty similar.
re shared facilities, I wouldn't allow students to do this without staff
present.  We did scratch our nozzle learning about this, but luckily
it didn't damage it enough to cause issue.  Our tool will allow people to
try to focus on pieces that are too small, but if they try to do it
pneumatically, it just smashes into the write head.  We limit pieces
to 10mm unless working with staff.

I'm curious how you guys coat samples that small.  That ended up being a
bigger problem than writing on them!  Happy to discuss more offline.
Best,
Greg

On Fri, Sep 26, 2025 at 4:14 PM Greg Holloway <greg.holloway at uwaterloo.ca>
wrote:

> 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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-- 
Greg Allion
NC State University Nanofabrication Facility (NNF)
Process Integration Engineering Manager

Monteith Research Center
2410 Campus Shore Drive rm.243F
Raleigh, NC 27606
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