BST - what is the weird layer at the bottom?

vinven7

Hello,

I was in the processing of depositing BST thin films on Platinized Silicon substrate from solution using spin casting. Six layers were deposited. Each deposition was followed by 400 celsius for seven minutes and 700 celsius for three minutes. The final film was annealed for an hour at 700 celsius. The grain size seems to be in the range of 40 - 60 nm.
When doing the cross section SEM i find that there is a weird looking highly damaged layer at the bottom of the film that is around 8 um thick. The film itself is around 500 nm thick.
Does anyone have any idea what this layer is? Have you encountered it before?
The film has lower capacitance than expected, I suspect that this might be a reason why.

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Danger

Sorry... I have absolutely no knowledge of the subject. All that I can think of is oxidation of the platinum in the substrate, but I assume that you have measures in place to prevent that.