For those interested in dry etching PDMS, I did finally find a way to dry-etch through a 10micron layer of PDMS on gold film in such a way that (1) the thin gold film underneath was unaffected and (2) the etch was clean (bare gold was left with no significant film on top of it). The method in this paper: Biomed Microdevices. 2007 Oct 4 A lithographically-patterned, elastic multi-electrode array for surface stimulation of the spinal cord. Meacham KW, Giuly RJ, Guo L, Hochman S, Deweerth SP. -Rick ------------------------------- This was my orginial question: [mems-talk] Selective, clean PDMS etch Rick Giuly Mon Apr 18 00:37:17 EDT 2005 Hello All, I have a 10micron layer of PDMS with a 5000A layer of gold under it. I want to dry etch completely through the PDMS without damaging the gold. The etch needs to be clean so that bare gold is exposed to serve as an electrode. Here's the recipe I'm using: CF4+O2 (75:25 ratio) power: 200w pressure: 47mTorr This recipe etches PDMS at about 5microns per hour but: 1. This recipe etches gold also - which means if you etch too long, you loose the electrode. The PDMS layer is not uniform enough for me to time its etching perfectly (in hopes that the gold will not be reached), and our Plasma Therm RIE machine doesn't etch uniformly either. 2. This recipe creates a residue that remains even as it etches through underlying gold. Pure oxygen plasma may do the trick - I'm not sure - but I know it would take an extremely long time. Does anyone know of a PDMS dry etch recipe that is selective (won't etch gold), clean, and reasonably fast (better than 2 microns per hour). After writing this message I'm thinking I could do the CF4+O2 for a while and then switch to pure O2, but I'm not sure if that's the solution. I would appreciate some advice - exploring possibilities has been an extremely time consuming process. Richard J. Giuly Bioengineering Graduate Student National Center for Microscopy and Imaging Research (NCMIR) University of California, San Diego rgiuly at ucsd dot edu