Hi Josh,

We also use weight gain as a process control tool.  We use a reduced Oxide
system and check weight loss after microetch, weight gain after oxide and after
reduction. The weight gain is controlled so as not to produce too thick a layer
of oxide.  I agree with you as to the use of SEM's; they may show crystal
structure, but that is about the extent of their usefulness.  We also do
routine peel strengths. I'm suprised that you get 1 PLI on polyimide with a
non-reduced oxide. That is about the mean peel strength we get with our reduced
oxide bath.

Regards,
Les

>  From: [log in to unmask], on 10/28/98 1:08 PM:
>  We use oxide weight gain as a process control on our oxide line.  Recently,
>  it
>  has been suggested that I consider using oxide peel strength tests as some
>  sort of process indicator.  It has also been suggested that SEM's of the
>  oxide
>  surface would be helpful in some way.
>
>  I have always thought that SEM's were good for looking at oxide growth
>  structure, but not for thickness or anything else.  I have the following
>  questions:
>
>  1.  Is anyone using SEM's of oxide surface for a regular process
>  control/indicator?  What are you looking for in a SEM?
>
>  2.  What peel strength should I expect to see from a non-reduced oxide in a
>  polyimide application?  I've always thought that anything over 1 lb/inch was
>  good.  Is there some industry spec or standard for polyimide peels (oxide)?
>
>  Thanks,
>
>  Josh
>
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