Dear MEMS colleagues,

Does any one know how to protect the PZT thick film(about 30um) in KOH
ecthant?
One side of the wafer is the PZT pattern,and the other side is ecthing
pattern.
I have tried some methods to avoid it, but fail:
1. use nobal metal (Au) to protect PZT --> too expensive, and the Au
will be etched.
                                                            Its surface
profile is like the moon surface.
                                                        -->NG.
2.use thick PR to protect -->  PR will be lifted.
                                     --> NG.
3.use jig to protect PZT --> use two o-rings to protect the wafer and
locked by screw.
                                       when the thickness of the wafer
is thin during the ecthing process,
                                       the wafer will break.
                                   --> NG.

Can anyone give some suggestions to solve this problem?
I will appreciate your response.

Ralph