You may want to try ProTek PSB coating by Brewer Science. It can be used in place of a photoresist. I have tried this and found it to be a good solution. However, it did not survive long KOH etching, but it might be ok for shorter etches. On Sat, May 6, 2017 at 7:42 PM, Andreas K. Huettel < andreas.huettel@physik.uni-regensburg.de> wrote: > Dear all, > > we need to etch deep holes into a Si wafer (with a 500nm surface oxide) > that > already has sensitive Nb structures on top. > > The etching alone works mostly fine with first RIE through the oxide and > then > hot KOH. However, the KOH also dissolves our photoresist and then attacks > the > niobium. > > We already tried placing a baked-out PMMA layer between niobium and > photoresist, but that didn't help too much. > > Do you have any advice for this? > Are there any photoresists around that are KOH-stable? > What other protective could be used that later are easily removed? > > Best, > Andreas > > -- > PD Dr. Andreas K. Huettel > Institute for Experimental and Applied Physics > University of Regensburg > 93040 Regensburg > Germany > > tel. +49 151 241 67748 (mobile) > tel. +49 941 943 1618 (office) > fax +49 941 943 1670 > e-mail andreas.huettel@ur.de > http://www.akhuettel.de/ > http://www.physik.uni-r.de/forschung/huettel/ > _______________________________________________ > Hosted by the MEMS and Nanotechnology Exchange, the country's leading > provider of MEMS and Nanotechnology design and fabrication services. > Visit us at http://www.mems-exchange.org > > Want to advertise to this community? See http://www.memsnet.org > > To unsubscribe: > http://mail.mems-exchange.org/mailman/listinfo/mems-talk > > _______________________________________________ Hosted by the MEMS and Nanotechnology Exchange, the country's leading provider of MEMS and Nanotechnology design and fabrication services. Visit us at http://www.mems-exchange.org Want to advertise to this community? See http://www.memsnet.org To unsubscribe: http://mail.mems-exchange.org/mailman/listinfo/mems-talk