I've seen that before: blisters in poly (dep temp = 610 C) when depositing
over unannealed PSG (dep temp = 450 C).
We guessed that it was due to hydrogen outgassing.
The solution is to anneal the PSG at 1000-1100 C for an hour before
depositing anything else on it.
    --Kirt Williams

----- Original Message -----
From: "¤ý§µ©¾" 
To: 
Sent: Thursday, October 06, 2005 1:22 AM
Subject: [mems-talk] multilayer stress


>
> 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