Hi, You could try XeF2 to etch the Si perhaps Mike ----Original Message----- From: Aarthi lavanya [mailto:cqtald@nus.edu.sg] Sent: Fri 15/04/2011 07:01 To: mems-talk@memsnet.org Subject: [mems-talk] Si Etch with KOH Hi, I have structures sitting on Si wafer and it is covered with layer of Su-8. The main idea is to etch away Si and have a Su-8 layer with structures on it. I've been trying to etch Si using KOH and always end up with gooey looking liquid and the Si looking all messed. Suggestions please .. Cheers Aarthi