SU-8 recipe

Mary Tang 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 
future reference!) 

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

-- 
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
(650)723-9980
mtang at stanford.edu
http://snf.stanford.edu



Eric wrote:

>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
>thin SU8.
>
>Example from Mark Shaw:
>
>Eric,
> 
>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,
>
>-----Original Message-----
>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
>
>Hi,
>
>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,
>Kazuhiko
>
>------- 
>Kazuhiko Yamanaka
>Harris Group, Solid State & Photonics Lab,
>Center for Integrated Systems,
>Stanford University
>CIS-X Rm 126X,
>Stanford, CA 94305-4075
>Tel :    (650)725-6909
>Fax:    (650)723-4659
>E-mail : yamanaka at snowmass.stanford.edu
>  
>






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