Rick:
The photochemical reaction of novalac-based positive resist causes nitrogen
to be evolved during exposure.  If the bubbles form only when photoresist is
present, then it is likely that this is the source of your gas bubbles.  One
way to eliminate the bubbles is to reduce the exposure intensity while
keeping the dose constant.  This will give the nitrogen more time to migrate
through the thick resist layer.  I have used a pulse exposure technique in
the past, with a 20-30% duty cycle.
Brad

On 11/28/04 7:56 PM, "Rick Giuly"  wrote:

> Hello All,
>
> Listed from top to bottom, I have these layers:
> 8 micron AZ P4620 photoresist (spun on)
> ..5 micron gold (ebeam at ~10e-6 torr, 5A per sec)
> 10 micron PDMS (spun on)
> glass substrate
>
> When I expose with UV light, gas bubbles form between the gold and the
> PDMS. They do not form if there is no photoresist.
>
> Any ideas on where the bubbles come from and how to get rid of them?
>
>
> -Rick Giuly
> GA Tech
>
>
>
>
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