Hello, everyone,

I need to implement a double-layer resist structure consisting of
S1818 on the bottom and S1805 on top.  This is for a lift-off
application.  I have to use these two resists because things like PMGI
don't work very well with other steps involved in the process.  Simply
flood exposing the bottom layer and spinning the top layer does not
work, presumably because the layers mix.  Could anyone suggest a
surface treatment that would keep the two layers separate?

I would most prefer to avoid coating with metals and then etching them
because that's very time consuming.  Ideally the surface treatment
would permit one-step development with MF319 or a similar developer,
but its ok if I have to use multiple developers. I would be thankful
for as many suggestions as possible, that way one of them might be
available in my cleanroom facility.

thank you,
-mikas