Hi all,

We are trying to etch a TiW adhesion layer on an Alumni substrate using
Clariant's TiW etchant.  We're observing a residue film (pinkish on the
white Alumina) that can be rubbed off using a Q-tip.  However, we don't
know how to remove this film from our patterned substrates.  We've tried
acetone, stripper, and RIE in an oxygen plasma, but the film remains.
It seems manually wiping off the film has the best results, but this
ruins the structures (1.5um of Au with TiW adhesion layer).

Has anyone observed this in the past?  Btw, we believe this film may
have something to do with having left the light-sensitive TiW etchant in
the light for too long.  The residue also remains after being dipped in
fresh TiW etchant at 37C.

Thank you for your time!

Stella Chang
University of Waterloo