Hello Zhiyan, Do you mean what mask to use for dry etching metal? If so, normal photoresist should work for that. I have used a standard thin resist (Shipley Megaposit SPR 700-1.2) for etching aluminum with Cl2/BCl3. I etched 2 microns of aluminum with about 1.5 microns of resist. Hope this was what you wanted to know. Sjoerd Haasl Royal Institute of Technology Stockholm, Sweden -----Original Message----- From: Zhiyan Liu [mailto:zhiyanl@engr.colostate.edu] Sent: den 30 oktober 2004 00:06 To: mems-talk@memsnet.org Subject: [mems-talk] Dry etch mask Dear all, Does anybody has an idea of the dry etch metal mask. The dry etched i used are Cl2/BCl3. Thank you , Zhiyan