Hello,

I've used NR9 for a few years now and have had good results with it since
developing a robust recipe for it.  However, in the past year I've noticed
that NR9 seems to leave some sort of invisible residue behind on many
materials.  If the area of interest is Au for example, I can generally get
ohmic contact with Ti/Au contacts patterned with NR9, but the second layer
of metal often peels off during wirebonding.  When I try to make ohmic
contacts to highly doped p-type Ge with Ti/Au patterned with NR9 the
contacts are only ohmic for large areas, which is not the case when I
pattern the contacts with S1813.

Normally I would just ash for 1 min in oxygen plasma prior to deposition,
but here I can't do this because it would either damage the surface of the
Ge or an isolation layer in our device of hard-baked SU8 2000.5 .  I spoke
with the Futurrex engineer about this, but all he could suggest was to
adjust the bake times, which didn't make any difference.  Does anyone have
any other ideas I could try?

In the meantime we have been using S1813 to do the deposition, but it's a
hassle to do liftoff since our contacts are usually 2kA or more thick.
I'm planning to buy a LOR resist to do two-step processing, and I was
thinking about LOR 3A since I use the metal-ion free developer MF 319.
However, I noticed that a lot of the people on this site use LOR B with
that same developer, even though MicroChem seems to not recommend it.  Is
there any particular reason to use one or the other?  Should I try the
trick with hardening the top layer with toluene first?

Thanks,

Alex