Hello,
There is still some solvent in the unexposed SU-8. So during the
soft-bake (and the post-exposure bake) we observed a strong
outgassing. (don't know what kind of gas)
We made some experiments to perform the soft-bake on a hot-plate
with a top cover. The Su-8 remained soft and gluey even after
1 hour.
So I think, the gold cover prevents the outgassing, leading to
the destruction of the surface.
Good look with your experiments
Christoph Friese
____________________________________________
Dipl.-Ing. Christoph Friese
IMTEK - Laboratory for micro-optics
Georges-Koehler-Allee 102
D-79110 Freiburg
Germany
Tel.: ++49 761 203-7575/7566
Fax.: ++49 761 203-7562
Mail: [email protected]
Web : http://www.imtek.de/micro-optics/
____________________________________________
> -----Ursprüngliche Nachricht-----
> Von: Anthony Holland [mailto:[email protected]]
> Gesendet: Samstag, 10. April 2004 02:28
> An: [email protected]; [email protected]
> Betreff: Re: [mems-talk] SU-8 wrinkles after bake
>
>
> the wrinkling may be due to the glass transition temperature
> being too low. I have observed this problem with aluminium on
> other polymer films. I understand that a higher baking
> temperature before metal deposition can increase the glass
> transition temperature in some polymers and hence prevent the
> surface flowing, causing wrinkles in a subsequent heat process.
>
> I noted that the wrinkling did not occur when there was no
> metal, irrespective of the heat processes. Can anyone explain this?
>
> Good luck
>
> Anthony Holland
>
>
>
> Dr. Anthony Holland
> Research Fellow
> Australian Photonics Cooperative Research Centre
> School of Electrical and Computer Systems Engineering
> RMIT University
> GPO Box 2476V
> Melbourne
> VIC 3000
> AUSTRALIA
>
> Tel. 61 3 9925 2150
> Fax. 61 3 9925 2007
> >>> [email protected] 04/10/04 3:50 AM >>>
> Hello all,
>
> We met a SU-8 wrinkle problem and would like to
> hear any suggestion. The process is to pattern gold on
> the un-exposed SU-8 resist. We first piranha etched
> the glass slides and baked it for 1hr@200C. The
> spun-on SU-8 resist looked good after soft bake. Then
> gold was sputtered onto the resist, and it was
> patterned by using Shipley 1813 positive resist. After
> that, the gold was etched in Transene gold etchant TFA
> (a complex of KI/I2), rinsed in DI water, baked at 90C
> for 30 mins. The wrinkles showed up during the baking.
> Does anyone have the same experience? Any suggestion
> welcomed.
>
>
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