I've had this trouble with platinum before, as well. In my case, it was
because the deposition pressure was too high.

My source had been contaminated (likely with carbon), and it was
evaporating at 10^-5 torr. It had to be cooked for a good long while to
get down to 10^-6 torr.

Even at that pressure, I had to stop every 500 A to let the PR cool down.

Lower pressure means lower temperature of the source.

What was your deposition pressure?

Jesse Fowler



From:   Andrew Sarangan 
To:     General MEMS discussion 
Date:   03/31/2011 15:55
Subject:        [mems-talk] Platinum e-beam evap liftoff
Sent by:        mems-talk-bounces+jesse.d.fowler=aero.org@memsnet.org



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?