[labnetwork] ZEP worth it?

[Gustavo de Oliveira Luiz]

Hi Long,

The main problem with ZEP, as I see it, is it's cost. Other than that, it's
very reliable, has better contrast than PMMA for the same conditions and
produces very good results, not to mention that the selectivity to plasma
etch is considerably better than PMMA. As for the dose to clear, in my
experience working at 10 kV and 30 kV, ZEP requires about 1/3 of the PMMA
dose to clear.

Regarding shelf life, I've recently tested a batch that expired back in
2015. Patterning wise, it worked just as well as a batch that we bought at
the beginning of this year.

The choice between PMMA and ZEP, at least to me, boils down to application
requirements and budget. If your application requires very smooth edges, or
etching a little deeper without losing much resolution and you can afford a
few $1000 for 100 mL of resist, I'd work with ZEP and perhaps consider
using cold development to increase contrast. Otherwise, PMMA is a very good
resist in general, and you can still try cold development to improve
contrast and obtain very good results.

Cheers,
--
Gustavo de Oliveira Luiz, PhD
Applications/Research Specialist
nanoFAB, University of Alberta
+1 (780) 619-1463

On Thu, Apr 29, 2021 at 9:46 AM Chang, Long <lvchang at central.uh.edu> wrote:

> Hi Guys,
>
> I have no experience with ZEP, but the data sheet suggest a critical dose
> of ~35 uC/cm2, approximately 1/10 of PMMA. What are the problems with ZEP
> and under what conditions is it worth the cost? Does it last forever in
> storage like PMMA?
>
> Thanks,
> Long
>
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