Chad,

I'm aiming for >= 20 microns resist film. I use the SU8-2015. I tried today
14x16mm samples and the results are better but not what I expected.

Thanks for the help.

Patrick Poissant

----- Original Message -----
From: "Brubaker Chad" 
To: "General MEMS discussion" 
Cc: "Brubaker Chad" 
Sent: Tuesday, March 30, 2004 10:46 AM
Subject: RE: [mems-talk] SU8 spin-coating


Patrick,

I have a couple of questions.

First, what film thickness are you aiming for?

And, second, which grade of SU-8 are you using (i.e., SU-8 25, SU-8 2050)?

If you are creating a pretty thick film, one thing you can do is greatly
extend the high temperature (95C) bake step, or perhaps perform an
additional bake step in an oven at 95 C (for several hours).  It probably
won't completely take care of the problem, but considering that the Tg of
SU-8 is 55 C, some reflow will occur during that period to reduce the height
of the edge bead.

If you can manage it, try to use a thicker grade of SU-8, which will allow
you to spin on at much higher RPM.  This can do a lot to minimize edge bead
(although you will still have some pretty big problems at the corners of
your substrate).

Since your samples are small squares, there is not a whole lot else that can
be done to reduce the edge bead.


Best Regards,

Chad Brubaker

EV Group       invent * innovate * implement
Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail:
[email protected], www.EVGroup.com

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 -----Original Message-----
From: [email protected]
[mailto:[email protected]]  On Behalf Of
Patrick Poissant
Sent: Monday, March 29, 2004 6:12 PM
To: [email protected]
Subject: [mems-talk] SU8 spin-coating

Hello,

I have small samples (1cm square) and try to spin-coat SU8 resist on it. I
apply my ressit with a pipette directly on the samples and then spin-coat. I
also try to spin slowly when appling the resist. These two ways produce big
edge bead. How do you spin-coat SU8? How big are your samples?

Best regards,

Patrick Poissant
___________________________________________________
   M.A.Sc. Student
   Dept. of Electrical Engineering
   Université de Sherbrooke
   Sherbrooke (Québec) J1K 2R1
   CANADA
   [email protected]
   Sherbrooke Microelectronics Research Group
   www.gel.usherb.ca/gms

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