Sorry to here you still have problems. How much better is the adhesion on bare silicon? Also, are you making microchannels actually in the SU-8 or is this for a mould. I.e. are you exposing a large area of the wafer? If so, then it may be worthwhile to try and reduce this area as much as possible and/or use a lower temperature PEB. For large area exposures, there will be a lot of stress in the crosslinked film which easily leads to cracking and delamination. Also remember to ramp up and down with the hotplate. Another thing I forgot to ask before was how you are pretreating your wafer prior to the dehydration bake? I have no experience of PECVD SiO2 but for silicon/glass you need to soak in conc. H2SO4 or piranha prior to the dehydration bake. However, poor pretreatment usually becomes apparent during spinning or softbake - are you getting a nice even film at this stage? As for HMDS, I have heard it said that this can actually make adhesion worse (never tried myself). There are products I have heard mentioned on this list which may be more appropriate such as AP300 and Omnicoat but again I have no experience of them. Steven Yang wrote: > Hi, all > > Asked some questions on SU-8 2050 several days ago, still stuck on it now. > > The problem is the peeling off at some SU-8 2050 microchannel > edge.(SU-8 2050 on PECVD SiO2). Without SiO2 layer, the situation will > get better with seldom cracking and peeling off. However, on PECVD > SiO2 it always turns out this problem more or less. > > I have increased the temperature and time for dehrydration at 180C for > 30mins. and exposured for 40s at 7mW/cm2, PEB at 65C, 95C for 5 and 15 > mins respectively (Same as softbake). No much different. > > If there is no any further solution based on recipe modification, will > the HMDS get the thing better? If so, could anyone give some > suggestion on the HMDS spin procedure? below is what I plan to do. > 1) dehydrate at 150C for 15mins > 2) spin HMDS at 7500rpm for 35s > 3) dehydrate at 150C for another 15mins > 4) spin SU-8 2050 at 4000rpm for 45s > > Any suggestion? Thanks a lot! > > Steven >