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