Suresh, According to my tables (Williams and Muller, JMEMS V.5#4), LPCVD SiN only etches at about 5nm/min in 49% HF. Since the annealing step is making your PECVD SiN more like LPCVD, you may just need to let it etch a little bit longer. Maybe 30 minutes, maybe longer. SiN can't become proof to HF, right? So, it's just a matter of time. Jesse Fowler UCLA/MAE Dept., 420 Westwood Plaza, Room 37-129, ENGR IV Los Angeles, CA 90095-1597 | (310)825-3977 "We did our best but God didn't want to give us any goals." -- Saudi Arabian goalkeeper Mohammed Al-Deayea (World Cup 2002) On Tue, 25 Jun 2002, Suresh Uppal wrote: > Dear All, > > I wonder if someone has a solution to my problem.. > > I have a Ge substrate on which 200 nm SiO2 and top of that 200 nm SIN film was > deposited ( PECVD). After annealing at high temperatures, HF etch does not > get rid of the deposited nitride layer though it does uniformly before > annealing. I have tried etching for more than 15 min in HF (48 %). > > Any suggestion. Please send email directly at suresh@soton.ac.uk > > Regards, > suresh > _______________________________________________ > MEMS-talk@memsnet.org mailing list: to unsubscribe or change your list > options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk > Hosted by the MEMS Exchange, providers of MEMS processing services. > Visit us at http://www.memsnet.org/