Dear all,
I have SU-8 as structural material of my MEMS device. I want to make electrical contacts over SU-8 structure. Which will be the best metal that suits for this application? Can titanium be used for this?
This site is a good reference for SU8.
http://memscyclopedia.org/su8.html
According to them, Al and SU8 have the best adhesion. You may want to do a hard bake of the SU8 before depositing the metal to improve the mechanical properties of the SU8. Good luck!
Hello Jose,
Below is a paper that reports bond strengths between SU-8 and Au, Ti, Al and Si. They also show that the adhesion can be improved with a promoter:
https://www.researchgate.net/publication/245128991_Investigation_of_the_bond_strength_between_the_photo-sensitive_polymer_SU8_and_gold
As Robert points out, Al offers a better bond strength than Ti. You should also consider the application when deciding the material though. As an example, I found that Cr ions in the adhesion layer diffused into the gold electrode layer during annealing, affecting the electrical properties of my device. A Ti adhesion layer did not present this issue.
Article Investigation of the bond strength between the photo-sensiti...
Hello Jose,
Are you still interested in this? We recently published a paper, where we coat SU-8 layers with a double layer of Ti/Pt:
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7438746
Let me know if you have any questions.
Hi Samuel,
I read the paper you posted where you coat the SU8 with a double layer of Ti/Pt. In the paper it is mentioned that the SU8 surface is activated with an oxygen plasma ash prior to metallisation. Is this a necessary step for good adhesion?
I am also trying to metallise over SU8, similar to Jose. In my case, i am using lift-off as opposed to sputtering. Would this pose a problem?
Thanks.
Rgds
Sankar peralagu
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