All SU-8 Users,

I wanted to take this opportunity to address both the adhesion and
plating questions raised by Mark Leonard at Heriot-Watt University and
his specific concerns of coating SU-8 on Copper seed layers...We have a
number of customers using OmniCoat in production on top of a variety of
coatings and substrates for improving the adhesion during
processing...What we have found is that the different refractive index
of the polymer in the OmniCoat layer provides some anti-reflective
properties and as such allows for a reduction in the required exposure
dose to something around the dose required for processing SU-8 on
Silicon...For example when usually working on Cu or Au we have found
that an exposure dose of close to 2X that on Si is required to get good
feature resolution and adhesion, mainly due to the reflectance
difference between these metals and Si....

An additional benefit of OmniCoat is that after processing the user can
realise the removal of SU-8 by soaking in Remover PG at a temperature of
60-80C for 5-15 minutes....If you require more details please do not
hesitate to contact me directly....

In the majority of cases HMDS does not work well with SU-8 and in some
cases can adversely affect the adhesion of the film to the
substrate...One of the key things to always remember when processing
SU-8 is to ensure the substrate is very clean and dry prior to coating
and that each of the processing steps, especially the exposure phase, is
optimised for that specific substrate...The key of the exposure phase is
to JUST create enough acid during the exposure and then allow the
cross-linking to take place in a controlled manner when heat is applied
during the PEB phase...

I hope these hints have been of use and if you need more specific
assistance please contact me directly...

Best regards,

Mark Shaw
Regional Sales Manager
MicroChem Corp.

Tel : 617-965-5511 ext 308
Cell: 617-407-9490
Fax: 617-831-2354