[mems-talk] Reflectivity with SU-8 on Au on Sapphire

[Dan Stark]

Dear All,

I am trying to pattern a 15 micron wide channel in 15 micron thick SU-8 10.
My substrate is a 1 mm thick piece of Sapphire with 100 Ang. Ti/500 Ang. Au
atop.  I can't seem to get the channel to come out.  If I use longer
exposure times, it looks like I've overexposed and the channels don't
develop. However, as I use shorter exposure times, my channel edges become
more and more rough.  I believe it is because the Au on Sapphire is
reflecting more and causing the SU-8 to partially expose where it shouldn't
be.  I'm not sure though.  Any ideas on how to get the channel to develop
with clean lines?

Thanks,
Dan