Hi, I tried same thing with 500nm PECVD nitride at 100oC of KOH, but there was no problem. Maybe your thickness is too thin. However there are a lot of pinhole in PE nitride from which the KOH solution penetrate thru, so you'de better use LP nitride. Jeehwan -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Ziaur Rahman Sent: Monday, May 01, 2006 3:04 PM To: mems-talk@memsnet.org Subject: [mems-talk] PECVD Silicon Nitride Recipe for KOH etching Hello, I used PECVD Silicon Nitride as a mask to etch silicon using KOH solution. But the silicon nitride film peeled off when I put the wafer in KOH solution (44% weight at 85 C). If I anneal the silicon nitride film will it work? Can anyone give me a good recipe for PECVD Silicon Nitride which will work as mask for KOH etching?