Hello Michele What exactly are you trying to do that takes such a long etch. Xenon difluoride is an isotropic etchant of silicon with nearly infinite selectivity between silicon and both photo resist and polyimide so it may be ideal for your application. Please give me a call or send me email with more details on what you are trying to do and we can talk about it. XACTIX is the overwhelming market leader in providing equipment for etching silicon using XeF2 so we have the expertise to let you know if it would work and can help you run some samples if an experiment seems worth it. Best Regards David Springer >> Hallo, >> does anyone know if there is a photoresist or >> photosensitive polymmide that can resist a 30 hour >> etch in KOH or TMAH? >> Can you also suggest the best etching conditions for >> the highest selectivity for that matirial and silicon? >> Thank you very much. >> Michele >> ______________________________________________________________________ >> Yahoo! Mail: 6MB di spazio gratuito, 30MB per i tuoi allegati, >> l'antivirus, il filtro Anti-spam >> http://it.yahoo.com/mail_it/foot/?http://it.mail.yahoo.com/ >> _______________________________________________ >> 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/