I need some advice about using NMP (methylpyrrolidone,i.e. N-Methyl-2-Pyrrolidone) to clean samples. At the moment I am measuring devices that are made from 200 nm of patterned niobium on top of SiO2/Si or sapphire substrates. The devices are very sensitive to the properties of the surface, any form of organic impurities, dirt, resist residues etc will degrade the performance. It is therefore important to clean them properly. Up until now I have been using warm acetone followed by IPA to clean them. This usually works reasonaly well but does not always remove all the organics). Anyway, a colleagues recommended trying NMP instead. However, I have no experience with NMP and I am a bit worried that it might damage the niobium somehow. Does anyone know if NMP is as "safe" as e.g. acetone when it comes to cleaning metal surfaces?