Kevin, Apart form using Ti as an adhesion layer, I am also using Ti as a layer = to block underlying uncrosslinked SU-8 from being exposed to UV during = subsequent photolithography steps after the Ti layer has been deposited. = It has been reported that uncrosslinked SU-8 has been done before and = the blocking metal layer was at least 25nm of Chromium. Here I am using = Titanium as a blocking layer as Ti is biocompatible, whereas Chromium = has been known to inhibit Polymerase Chain Reaction. Jeffrey ________________________________ From: mems-talk-bounces@memsnet.org on behalf of Kevin Paul Nichols Sent: Mon 2/26/2007 9:33 PM To: General MEMS discussion Subject: Re: [mems-talk] Gold on SU-8 If what you really need is an adhesion layer for SU-8 and Au without=20 resorting to Ti or Cr, you should look at "Investigation of the bond=20 strength between the photo-sensitive polymer SU-8 and gold" where=20 Nordstr=F6m et al report using 4-aminothiolphenol (4-ATP) as a good=20 adhesion layer for SU-8/Au. In short, the amine on 4-ATP reacts with=20 the SU-8's epoxy, and the thiol bonds to the Au. They also list a few other iterations that they had luck with. It's a=20 good, comprehensive paper on the subject. The link is here: http://www.sciencedirect.com/science/article/B6V0W-4F5S6C5-7/2/e59903c5e0= 903d82c14a43c5cbb36c38 Regarding your process overall though: 1) With the Cr/Ti adhesion layers, you only need 10 - 20 nm for good=20 adhesion. This should take about 5 minutes (at most) on most=20 equipment (evaporation or sputtering). I don't think this should=20 really be a problem. 2) Regarding omnicoat, don't use this if you want to make a=20 "sandwich." Unless your Au layer is unpatterned, it will give you=20 issues when you try to adhere SU-8 to SU-8. 3) Au adhesion on SU-8 isn't great, but if you're careful you can=20 still pattern it (just be sure to build in a margin for=20 undercutting). And, if you have it in a "sandwich," it should be=20 secure enough in most cases. I honestly doubt you'll need an adhesion=20 layer at all.