Try H2O2 at 40oC-50oC. It takes arround 0.5-1 hour to etch.
It will not attack Al.

>
> Dear all,
>
> I am trying to etch Ti(300 Angs),which has aluminum
> layer underneath it.I have used TiW-30 (25-40C)from
> transene.I could see that after some time the Ti etch
> rate reduces completely and etch almost stops.I think
> due to the formation of Tio2 the etch rate drops.
>
> Can anyone suggest me a good Titanium etchant that
> should not attack Al.
>
> Your suggestions are highly helpful.
> Thanks
> Kris
>
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Best Regards,
Kin