During my work with SU-8, especially the thicker resists, the bubles
occured already during pouring out the resist onto the substrate.
That happend always during the initial "pouring out" and the end of that.
If You start and end to spill outside of the substrate, those bubbles
should be history.
I think big heigths of pouring out onto the substrate can also create
bubbles. Try to minimate those.

Greats from Sweden

Jan Oberth

P.S: Try to minimize the SU-8 outside of the substrate - cleaning the
mess can be really annoying.


----- Original Message -----
From: "Jiang Ziling" 
Subject: [mems-talk] su-8 air bubble problem

  I am using Su-8 and frequently there are air bubbles left in the
film after spin coating. It is more serious with thicker films. I
tried to get rid of them by putting the pre-spinning resist-coated
wafer in vacuum dessicator, but the bubbles won't go. Anyone have
experience in this?