> I have deposited Ti (80 nm) onto SiNx (200 nm) on Si. The Ti was then
> oxidised at 600 C. Bubbles have formed on the surface of the TiO2
> following oxidation. Has anyone experienced a similar effect?

By SiNx, I assume it is PECVD.
PECVD films have a LOT (easily 20%) of hydrogen.
Annealing makes the hydrogen come out and can cause bubbling.
In my experiments, depending on their deposition conditions,
some PECVD SiNx bubbled upon annealing.
Thus, it could be the SiNx alone that is bubbling.

        --Kirt Williams Agilent Technologies