Hi

Is anyone can help me figureout this question.
Here is my structure:

Poly5K+P-dope (-100Mpa)
------------
PSG6.0um      (-90Mpa)
------------
Poly10K+ P-dope(-150Mpa)
------------
PSG2.0um         (-90Mpa)
-----------
Si wafer

Why the bubbles showsup after Poly5K+P-dope  . And the wafer has serious
bending.
If I change PSG6.0um stress,The film of Poly5K cracked too.
I have tried anneal after PSG6.0um deposition, but still no work