Hi,

as the others reported, the correct solvent is PGMEA not the AZ edge
bead removal .

But with this resist you will never be able to dilute it down to 50nm,
no way !

This resist is intended for thick layers, so exactly the opposite of
what you want.

I would try to start with the thinnest resist possible. I don´t know
what product clariant offers for thin layers, because we also use only
the thicker resists like 5214, 701mir, 9260 etc. from them

The default thickness should not be above 600nm IMO to have a chance to
dilute it down to 50nm.

 From Shipley/Rohm & Haas there are resists like UV6m UV210, UV135 etc.
They start with lower default thicknesses.

I could dilute UV6 ( 600nm standard@3000rpm) down to ~100nm, although
the layer wasn´t that good afterwards. The practical limit was somewhere
in the 150-180nm range.

But there are some other and newer products. Check Siber resist system (
~150nm standard), UV210 ( 300nm standard) etc. and dilute it with the
right solvent ( here it is not PGMEA, but DEC11 in case of UV6).

But 50nm is way thin ! You will always have problems with thickness
homogenity and defects, but it it may not be impossible.

Another way...much better I think...would be to use a 2nd layer like
Barc. Etch it in O2 Plasma and strip the resist in Aceton, but the barc
will stay. You can easily buy Barcs in the range of 60nm and the layers
are very good.
If you want a sample...no problem.

Why do you indend such a small layer...by the way   :-)


Greets


Holger