Hi Thomas,

I have worked with deposition of PSG, admittedly thinner layers than you
are looking at and found that at P concentration of greater than 8wt% we
get outgassing of the phosphorus.  As Mike Pederson suggested, deposition
in steps with annealing in between might solve your problems, but I would
also include an undoped thin silicon dioxide layer, which will become doped
with phosphorus from the PSG layer during annealing, and cap the PSG for
the higher wt%.  Otherwise you tend to get the formation of phosporic acid,
which can be damaging to certain metals.

Helen.

Dr. Helen Berney
National Microelectronics Research Centre, Prospect Row, Cork, Ireland.
Tel +353-21-4904010  Fax +353-21-4270271   Email [email protected]
http://www.nmrc.ucc.ie/research/transducers/index.html

Jon Doe wrote:

>  Hi all:
> We are trying to deposit 4 to 10 um thick PSG with 7
> to 14 wt% P in a Lam PECVD system. We are experiencing
> very high stress and the film cracks and peels of
> after an anneal.
> Has anybody experience with such thick doped glass
> films. If so, How did you overcome the stress?
>
> Thanks for your input.
>
> Thomas
>
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