Rama - Since water is not miscible in acetone what is most likely happening inside what I assume is an atmospheric dryer is the acetone vapor is leaving the surfaces at a much faster rate leaving the water behind on the surfaces to evaporative dry which leaves watermarks or spots which can cause striation problems. We have a solution for this using our proprietary vacuum process. Feel free to write me for more information. I am careful not to put too much information in an email that might be seen as using the discussion board for commercial purposes. Thanks. Jack Mulligan HyperFlo jmulligan@hyperflo.com -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Ramakrishna Kotha Sent: Thursday, June 26, 2008 12:34 AM To: mems-talk@memsnet.org Subject: [mems-talk] Critical Dry Hi, I am performing critical dry to release a parallel plate structure, which has SiO2 as a sacrificial layer After removing the sacrifical layer-SiO2 with BOE, then the device is transffered to DI Water and then to Acetone in the critical dry chamber. After performig critical dry process using Polaron-CPD 7501 tool, all the structures are damaged (due to stiction problem). Can anyone, suggest me the accurate process to perform critical dry. Thanks in advance Rama