Image reversal allows side wall angle to be manipulated from -22 degrees through vertical to + 22 degrees. We have run 40 micron thick photoresist. We have never experimented with photo sensitive Polyimide but I am willing to run free tests because I am sure it would work. Vertical side walls thick protective layer, with the chemical and heat resistance of Polyimide. Sounds like the solution you require. Bill Moffa Mr. Lu, Thanks for the information. I am trying to etch 200u+ deep channels. Does crystal bonding work to this depth? I attempted thermal grease but local heating effects etched the photoresist away quickly in certain parts. Would you be able to comment on the sidewall angle for the structures you had etched? Thanks Shree _______________________________________________ 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