The effect of a number of other organic solvents, such as tetrahydrofuran, gamma-butyrolactone, and dimethylformamide, was also tested, and none of them was found to permanently Figure : Discontinuous residues were observed on the surface by optical microscopy after SU-8 removal, but only in thick (> 100 µm) and highly polymerized samples. These residues were removed without difficulty by RIE ICP hydrogen plasma. The diameter of the field of vision is 400 µm.