Kirk,

Try longer softbake time. I'm using it in all MEMS products more than 8
microns. Approx 10 min @ 115 degrees hot plate.

Ha Vu
TRW NovaSnesor

> -----Original Message-----
> From: [email protected] [SMTP:[email protected]]
> Sent: Wednesday, January 16, 2002 2:56 PM
> To:   [email protected]
> Subject:      RE: [mems-talk] More problems w/ AZ4620.
>
> > I have unsuccessfully attempted to use 4620 recently.  The
> > problem that
> > I have had is a "bubbling" of the resist immediately after exposure.
> > The "bubbles" nucleate in all open areas.  The resist sheds
> > in circular
> > flakes from the open areas - sometimes even before
> > developing.  If there
> > are features surrounded by lots of open area, these features flake off
> > as well.  Has anyone else seen anything like this?
>
> Nitrogen is given off when the resist is exposed.
> Normally it is absorbed in the exposed resist and diffuses away,
> with any left being removed upon developing.
> With thick resists and high exposure powers (mW/cm^2), it can nucleate
> bubbles.
> Try the same dose but with a lower exposure power,
> or do the exposure in pulses to allow time for diffusion.
> Karl Suss had some success with pulsed exposures awhile back.
>
>       --Kirt Williams Agilent Technologies
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