If reflections are the problem, you can try spinning anti reflective coating
from Brewer science under the SU8\
Shay

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Diane
Atkinson
Sent: Friday, September 14, 2012 3:30 PM
To: General MEMS discussion
Subject: Re: [mems-talk] Issues with footing in thin SU8


Dan-
Oh thank you so much! Yes, it is on glass and we are doing it in hard
contact on a Karl Suss MA6 aligner. And we only  tired the  exposure at 60mJ
in hard contact, ( in soft contact we tried anywhere from 50 mJ to 350mJ )
but we are about to try higher exposure doses in hard contact . Thank you so
much for your help and I will let you know how this works out- Diane




.________________________________________
From: [email protected]
[[email protected]] On Behalf Of
Daniel Figura [[email protected]]
Sent: Thursday, September 13, 2012 5:21 PM
To: 'General MEMS discussion'
Subject: Re: [mems-talk] Issues with footing in thin SU8

Hello Diane,



Some ideas:

1) do you have transparent layers under your SU-8? Glass substarte, thick
oxide, ... -  the footing can be caused by back reflection from layers
underneath. It will be worse close to larger structures

2) are you sure that it is no caused by diffraction from the mask - do you
have good contact or controlled proximity during exposure? What is your mask
aligner?

3) Is your SU-8 sufficiently cross-linked? Sometimes what can happen is that
if your resist is not cross-linked enough, you are slowly dissolving some of
it during development step and during rinsing and drying you deposit the
residues along the structures. If you compare the thickness of your layer
before and after development and do not see significant thickness loss you
can discriminate this.





With best regards,



Daniel







Daniel Figura



smartfabgroupT Company



process consulting . data processing . fab software



Phone: +421 944 45 26 86



E-mail: [email protected], Web: www.smartfabgroup.com







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-----Original Message-----
From: [email protected]
[mailto:[email protected]] On
Behalf Of Diane Atkinson
Sent: Thursday, September 13, 2012 14:04
To: [email protected]
Subject: [mems-talk] Issues with footing in thin SU8



Hello,

       I am trying to process 4um of SU8 3005,and am having issues with the
footing at the bottom of my pattern, I t is about 1-1.5 microns. I have
tried several things and nothing seem to fix this problem, I am about to try
CEM, but am wondering if there is an alternative way to prevent this ,maybe
reduce the PEB ?  Thank you



Also,I tried to send this once but I am not sure if it went so I am
resending-

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Visit us at http://www.mems-exchange.org

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_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
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