Sokwon, STS advanced oxide etching system in our facility did this job with either photoresist or metal mask. Pyrex can be etched with a rate of ~0.3-0.5um per minute. A couple of microns deep should be no problem. Good luck, ------------------------------------ Hongjun Zeng, PhD MEMS/Nano Scientist Nanotechnology Core Facility (NCF formerly MAL) University of Illinois at Chicago 3064 ERF Building 842 W. Taylor St., Chicago, IL 60607 Tel. 312-355-1259, Fax: 312-413-0447 ------------------------------------ -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of sokwon Paik Sent: Tuesday, January 10, 2006 4:10 PM To: General MEMS discussion Subject: [mems-talk] Wet etching? Dry etching? Hi I need to etch out Pyrex glass for 1-5 micro meter. If the aspect ratio is good then I'll do 5 micro meter and if the aspect ratio is bad then I'll etch only 1 micro meter or 100nm is OK....... Could anybody tell me your dry etching ratio and wet etching ratio for Pyrex glass? I'll cover the wafer with S1818 which is not intended to etch out. I wonder whether RIE or wet etching do not attack the S1818 layer also.....