I would agree with Bill. I would try longer LOWER, ENERGY exposure.
I dont recall if you can vary the power on the lamp.

I recall the paper by Mary Long and have observed the same problem
way back.

Avi Laker

On Wed, Jan 13, 2010 at 4:36 PM, Bill Moffat
wrote:

> One possibility that comes to mind.  Very early technical paper by Mary
> Long in the 80's on bubble formation in thick resist at exposure.  17
> microns is pretty thick.  During exposure the heat of the exposure lamp
> causes bubble formation inside the resist.  If there is a bubble  partially
> on the expose section it will give a half circle in the resist line that is
> developed away.  Mary was at Motorola or Arizona University in Tucson when
> she gave the paper.  My colleague and I would have thought the problem would
> have been reversed, mouse bites in the aluminum because of the reflectivity
> of the aluminum.  Try longer gentler exposure.  Also when we got mouse bites
> in aluminum we increase the prime time from 5 minutes to 20 minutes.  The
> lower number of hydroxyl ions on metal require longer HMDS exposure for the
> same contact angle. Bill Moffat
>