wet etching TiO2 and TaO2

Dear Labmembers,

Would appreciate any pointers for the following problem that we are facing.
1. We need to wet etch TiO2 and TaO2 with selectivity to thermally grown SiO2.
2. This may require some non-HF based solutions or an HF based solution which has very fast etch rates for at least TiO2 or TaO2.

Please let me know if anyone has any information on this.

thanks much,
Regards,
Pawan