[mems-talk] EDP etch compatibility

[Michael D Martin]

HY, 
   Long etches in any of the anisotropic etch solutions is very challenging with metals already on them.  While EDP, KOH, etc. are selective to oxide, they are not perfectly selective. And for EDP you loose even more selectivity when it begins to oxidize (turn a dark brownish color).  So what happens is that the metal layers are undercut as the oxide is etched.  This problem is frequently made even worse by the presence of pin holes in the metals..  I think some people have a degree of luck using a second metalization in addition to the oxide masking layer.  This metal layer is often something like Cr/Au/Cr/Au.  Also there was a company developing a spin on coating for anisotropic etching, I think it was Brewer Science, not sure how it worked though. 


-Michael Martin
 U. of Louisville

>>> "Ho Yin Chan" <chanho1 at msu.edu> 9/11/2007 11:35 PM >>>
Hi,

 Currently, I am doing EDP process with Ti/Au/Ag stacks on SiO2. It is found
that the metal stack pattern has gone after EDP etch.  Could you share with
me your experience? I am guessing if the problem is caused by Ti.