[labnetwork] Current source for HSQ (FOx-16 / XR-1541)?

[Amir Safavi-Naeini]

Quick follow-up, I probably sent the initial email too quickly.

Just to clarify, FOx / XR-1541 is discontinued. DuPont ended production at
the end of 2025. Krayden declined to quote us this week, and Ellsworth
stopped distributing ealier.

Regarding other sources, here are some possibilities:
- DisChem Inc info at discheminc.com, mixes HSQ in MIBK at 1-20%
- EM Resist Ltd, info at emresist.com,

We understand that EPFL's CMi has moved to EM Resist and treats their 22%
as a direct FOx-16 replacement, and that Mike Rooks at Yale published a
comparison finding DisChem/AQM material equivalent to the Dow product given
a 120 C / 2 min post-apply bake.

So here are some narrow questions:

- Has anyone actually run DisChem or EM Resist HSQ at high resolution?How
does it compare on dose, contrast, and lot-to-lot consistency, and did you
need to change your process beyond the post-apply bake?

- Any other routes?

- Also curious whether anyone buys the powder and mixes on demand. Any tips
on this would be appreciated.

Still happy to summarize the responses that come back.

Thanks,
Amir

--
Amir H. Safavi-Naeini
Associate Professor
Department of Applied Physics
Ginzton Laboratory, Stanford University

On Tue, Aug 11, 2026 02:01 PM, Amir Safavi-Naeini <safavi at stanford.edu>
wrote:

> Hi everyone,
>
> We use HSQ as our high-resolution negative e-beam resist at Stanford,
> mostly for nanophotonic and quantum devices in lithium niobate and silicon.
> We've been trying to restock and have not been able to find a current
> source.
>
> Two questions:
>
> 1. Where are people buying HSQ these days? FOx-16, FOx-25, XR-1541, or any
> equivalent formulation. A vendor name and a contact would be enormously
> helpful. We only need a liter or two every year or two, so we are not a
> large-volume customer and that may be part of the problem.
>
> 2. If the supply situation is genuinely dead, what are people using
> instead for high-resolution negative-tone work, and what did you give up in
> switching?
>
> For what it's worth, we store ours in LN2, so shelf life isn't our
> limiting factor we believe...
>
> Happy to summarize replies back to the list if there's interest.
>
> Thanks,
> Amir
>
> --
> Amir H. Safavi-Naeini
> Associate Professor
> Department of Applied Physics
> Ginzton Laboratory, Stanford University
>
> mail address:
> Edward L. Ginzton Laboratory
> 348 Via Pueblo Mall, Box 336
> Stanford University
> Stanford, CA  94305-4088
>
> office phone: +1 650 498 7496  [Room 309, Spilker]
> mobile phone: +1 626 379 3702
> zoom: https://stanford.zoom.us/j/4970959839
> http://www.stanford.edu/~safavi/
> -------------------------------------------------
>
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