Dear Ivy, depending on what solution (with / without IPA) you plan to use, it might be worth while to look for a reflow bath. Such machines provide the best temperature constancy and permanent movement in the container itself. You could check out www.lotus-systems.de for further details. Perhaps you can find an American supplier with similar machines. When you use a magnetic stirrer, you should use an external source. Putting something into the bath always causes trouble. My very personal experience is that stirring does not influence the etch rate and quality too much. The other parameters, including pre-treatment of the silicon, have greater influence. Most important is to prevent the H2-bubbles from sticking or rolling over the surface (so put the wafer into the bath lying on one side, with the etched surface upwards). Otherwise they will mask the wafer and lead to a very rough surface. Especially for long etches, you should be aware that quartz also etches in KOH- solution. For constant results, it is best to use polypropylene for the bath container. Further tricks for a smoother etch can be found in the papers of Mihalcea in the Proceedings of the "Transducers" conference in Munich two years ago (and references therein). Hope this helps for the moment Stephan -----Ursprüngliche Nachricht----- Von: Liwei Wang [mailto:wangliw@auburn.edu] Gesendet: Freitag, 7. November 2003 23:19 An: mems-talk@memsnet.org Betreff: [mems-talk] Magentic stir in KOH etching Dear all: I am setting up a KOH etching station right now for deep etching Si (etch through the 500um wafer).I plan to have a constant temperature bath, a beaker, and a nice wafer holder to protect the backside of the film. my concern will be that do I need to have a magnetic stir set up in this KOH etching system? because it will be at least 10 hours etching, if so, how I gonna make it work? Put a magnetic plate in the water bath? or underneath the whole bath? does anyone have any experience or suggestions? Thank you so much in advance. Wish everybody have a nice weekend. Ivy _______________________________________________ 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/