For UV exposure doses slightly above the critical value determined by Gaudet et al. , the SU-8 removal is nearly instantaneous, but longer acid immersion times are required for higher UV exposure doses. In the case of thick and overexposed layers, ultrasonic agitation, longer acid submersion times (30 min) and moderate heating (40 • C) are required. In the later case, discontinuous residues were observed on the surface by optical microscopy after SU-8 removal (Fig. ). Profilometer measurements indicate a 400 nm height for the observed dendrites. Energy dispersive spectra of the X-rays emitted under examination with a scanning electron microscope indicate no trace of the antimony based salt used as a photoacid in SU-8. These residues are eliminated without difficulty after 480 s of attack in the RIE ICP hydrogen plasma described in Section 2.5, suggesting the residues are organic matter.