Stella,

We have seen similar pinkish residue after TiW etch
(in H2O2) on alumina and we have succesfully removed
it by dipping it back (for a second or so)in KII (Au
etchant). The pinkish residue may have come from one
of the following:

Contamination of TiW etchant from leftover residue
from gold etching (due to insufficent rinsing).

Very thin film of gold left behind from Au etching
(TiW gets etched right thru it, but it leaves behind a
pinkish residue).

Let me know if it works for you.
Regards,
Adnan Merhaba



--- Stella Chang  wrote:

> 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
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