I have seen this cracking effects particularly in Ti deposition. I think
it's because the deposition temperature is too high. Usually lowering the
deposition rate alleviates this effect.


Maggie Qianxi Lai
PH.D Candidate
Department of Mechanical & Aerospace Engineering
University of California, Los Angeles
http://www.chen.seas.ucla.edu/

-----Original Message-----
From: [email protected] [mailto:[email protected]]
On Behalf Of Andrew Sarangan
Sent: Wednesday, April 23, 2008 11:14 AM
To: General MEMS discussion
Subject: Re: [mems-talk] PR is all cracked after the deposition TiW

I have seen wrinkling effects during vaccum deposition on top of
photoresist, which we suspect is mostly due to outgassing of the solvents
from the resist film that are being trapped under the deposited film. This
is particularly bad with uncured SU8. Some resists with low solvent content
might behave better. Baking the resist film in a vacuum oven for several
hours before the sputter deposition might also help. I have also found that
evaporated films are less prone to this because they are somewhat porous and
leaves room for the outgassing.