Use APTES as diffusion barrier layer. The secret is to promote total dehydration then APTES as a vapor can react with all exposed areas. Resulting APTES barrier even though only 20 Angstroms thick stops all copper diffusion into Polyimide layer. Contact me directly we manufacture a Polyimide bake unit that bakes the polyimide correctly and we have now incorporated a APTES vapor delivery system onto this bake unit. Bill Moffat, CEO Yield Engineering Systems, Inc. 2185 Oakland Rd., San Jose, CA 95131 (408) 954-8353 -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Michael D Martin Sent: Friday, February 10, 2006 1:27 PM To: mems-talk@memsnet.org Subject: Re: [mems-talk] diffusion barrier for copper-polyimide Erikin, You might try using the polyimide adhesion promoter, VM-651 which I think will stick to metal oxides. -Michael U. of Louisville >>> erkin@virginia.edu 02/10/06 1:39 PM >>> Hi, I am trying to make micro strain gauges using the following method in summary: - Spin 250nm-thick polyimide diluted with NMP; completely cure at 325C - Sputter/pattern 80nm-thick Cu/Ni on cured polyimide - Spin 250nm-thick polyimide diluted with NMP; completely cure at 325C The problem I am having is that after the cure, the polyimide above Cu/Ni layer is disappearing. I read about copper oxide diffusion into polyimide due to the reaction between copper and polyamic acid; but I am not sure if this explains the material loss over the metal lines. I already tried amino silane adhesion promoters provided by GE Silicone, but didn't have any success. I would be grateful if somebody could suggest a solution.