Hi Florian,

You can remove the organic residues using an SC1 solution, consisting
of NH4OH, H202 and H20 in the ratio:1:1:5. The SC1 solution (in
various mixing ratios) is really the IC industry standard for wet
removal of organic surface contamination.

I am not sure how this will react with the TiO2 layer, but the absence
of H2SO4 should improve things. The Pirahna solution is a very
aggressive cleaning step, aimed at removing general surface
contamination (metal or organic) as a preliminary step to SC1 and SC2
cleans. The SC2 clean contains HCl (in substitution of NH4OH in SC1),
aimed at eliminating metallic contamination.

If you find that your TiO2 is still being etched, alter the mixing
ratio (add DI) or reduce the reaction time.

Good luck!

Michael


> ---------- Forwarded message ----------
> From: Florian Felderer 
> To: [email protected]
> Date: Sat, 05 Apr 2008 16:44:41 +0200
> Subject: [mems-talk] Does Piranha attacks TiO2
> Hi
>
> I am looking for a process to remove Polyimide residues but not TiO2.  I can
> remove most of the polyimide with a Microstrip 2001 solution but there a still
> residues left. We know that a piranha clean would remove these residues but
> we are uncertain if it also attacks the titanium dioxide
> Does anyone have an idea how we can remove the polyimide without damaging
> the (13-nm) TiO2 layer?
> We also want to avoid the use of an O2-Plasma because that would damage our
transistors.