mtang at snf.stanford.edu
Fri Jan 13 17:30:20 PST 2006
Hi everyone --
First, thanks Eric, for sharing this info (I KNOW I'm saving this for
Second, I was asked to clarify some lab procedures regarding SU-8, and
so thought I'd take the opportunity to do so here... Although Microchem
SU-8 is a wonderfully versatile and useful material, it is also
notoriously difficult to remove, once it's cured. And it self-cures
quite nicely. In the early days of SU-8, it would get everywhere in the
litho area, permanently clogging chucks and drain lines and making a
mess of benchtops and wafer cassettes. (Want to know how difficult it
is to get rid of cured SU-8? To paraphrase the Microchem website:
"SU-8 is a highly functional epoxy and therefore extremely difficult to
strip. Conventional stripper solvents... ...will not remove hard baked
(cured) SU-8. However, dozens of SU-8 users have successfully developed
stripping processes. Techniques include RIE plasma ashing, laser
ablation, molten salt baths, CO2 crystal and water jets and pyrolysis,
among others." I think they neglected to include heavy artillery...)
So... although SU-8 is allowed in the lab, there are certain
restrictions of where and how it can be applied and some additional
precautions for cleanup. Yes, it's a bit inconvenient, but it certainly
helps protect the equipment and other people's work.
Therefore, if you'd like to use SU-8 in the lab, you'll have to obtain
Mahnaz' seal of approval and get on her list of "qualified SU-8 users".
She will show you the tricks of the trade on how to manage and get the
most out of your SU-8 process, while keeping the lab clean.
Thanks for your attention --
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA 94305
mtang at stanford.edu
>Attached. I do this all the time. Let me know if you have questions. This
>mixes very quickly.
>BTW: I have observed that skipping the 95 degree prebake step and doubling
>the time of the 65 step on a hotplate gives better and more reliable
>resolution results. Likely due to the high solvent content. These films
>take a REALLY long time to fully cure.
>Microchem recommends a single bake step at 105 C for pre and post bake for
>Example from Mark Shaw:
>In order to dilute the SU-8 2015 you would need to dilute the product with
>SU-8 2000 Thinner according to the following calculations:
>Starting solids content of SU-8 2015 = 64%
>Starting solids content of SU-8 2002 = 29%
>Volume of SU-8 2015 = 100ml (for example)
>(64/29) * 100ml = Diluted volume = 220ml
>Therefore, 220ml - 100ml = amount of SU-8 2000 Thinner required = 120ml
>Check = 64/220ml = 29%
>I hope this helps,
>From: Kazuhiko Yamanaka [mailto:yamanaka at snowmass.stanford.edu]
>Sent: Thursday, January 12, 2006 10:18 AM
>To: labmembers at snf.stanford.edu
>Subject: SU-8 recipe
>I am trying to coat SU-8 on SOI wafer to make protect layer.
>The thickness of SU-8 is from 1um to 5um.
>Does anyone have the recipe of SU-8?
>Thanks for your help,
>Harris Group, Solid State & Photonics Lab,
>Center for Integrated Systems,
>CIS-X Rm 126X,
>Stanford, CA 94305-4075
>Tel : (650)725-6909
>E-mail : yamanaka at snowmass.stanford.edu
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