Andrew,

I would guess that the damage is worse now because you increased the
thermal gradient across the resist by cooling down the substrate.
If you could heat up the substrate holder or evaporate the Pt in
shorter cycles, I'd guess you'd see an improvement.

My 2 cents.

Felix

Felix Lu, Ph.D.
Applied Quantum Technologies, Inc.
Durham, NC

On Mar 31, 2011, at 5:07 PM, Andrew Sarangan wrote:

> I've been having trouble e-beam evaporating Pt on photoresist for
> lift-off, at 0.5A/s. The resist seemed to be cracking and/or reflowing
> after a few minutes, but it was ok since we only needed about 200A of
> Pt. The substrate temperature also rises pretty quickly, to about
> 150C. Assuming the resist damage was due to excessive heat damage, I
> installed a water-cooled substrate holder. Strangely, the resist
> damage is significantly worse now. It takes just 10 seconds before the
> resist becomes completely deformed, which can be visually seen through
> the viewport. Except for the substrate temperature, which is at 30C,
> everything else is identical during evaporation. Anyone has clues on
> what this could be due to?