Dear James,

Yes, this has been discussed before actually... :-) However, I'm quite intrigued
to see that you are working with the SU-8 3000 series! From where have you
purchased this? I have heard for a long time that MicroChem would put out a new
series of SU-8, but I have not been able to find out any more info about
it...could you fill me in? And in what way does the 3000 series differ from the
2000 series?? Have you tried any of the other series and have you so experienced
any differences?

About your question: low adhesion with SU-8/metal is a problem in general. We
have done a study on it and you can find the work in Microelectronic Engineering
78-79 (2005) 152-157. There are two things you could try: (i) increase the
exposure dosage, that generally improves the adhesion or (ii) use an adhesion
layer such as Ti or Cr, about 50 Å. Good luck!

Sincerely,
Maria

Maria Nordström, M.Sc.
PhD Student, Bioprobe Group
MIC - Department of Micro and Nanotechnology
Technical University of Denmark
DTU bldg. 345 east
DK-2800 Kgs. Lyngby
Denmark

Tel: +45-4525-5759
Fax: +45-4588-7762
Email: man@mic.dtu.dk
Web: www.mic.dtu.dk/Research/BioProbe.aspx

-----Original Message-----
From: James Zhu [mailto:james.zhu@epigem.co.uk]
Sent: 8. marts 2006 10:11
To: General MEMS discussion
Subject: [mems-talk] Problems due to poor SU8 adhesion to metal surface

Dear all,

I am new in this field and also this community.I am probably asking some silly
questions. Thanks for any help in advancen anyway.
I used SU8 3000 Series spin coated on nickel or silver surface. It was followed
by pre-bake for 11 mins at 95 C, exposure 7sec, PEB 1 mins @65C + 4 min @95C and
develop. Everything is ok until  electroplating in copper (strong acid) or gold
bath (strong basic) simply because Su8 layer detached from the metal surface.
Can anybody please give me some advice to overcome or just let me know ther it
is a unsolved problem.

Many thanks!

James