Did you thoroughly dehydrate the wafer prior to spinning? I would recommend
at least 250degC for 30mins on a hotplate. Otherwise your piranha may be
contaminated (it also needs to be freshly made which is why I prefer to use
just conc. H2SO4).
On Tue, Mar 31, 2009 at 08:54, wrote:
> hi all
> i am spin coating SU8 2050 on piranha cleaned silicon wafer but
> during prebake it is shrinking and coming into the center of the
> wafer. What could be the possible cause ?
> --
> Kamlesh Pawar
> M.Tech (Biomedical Engg)
> Mob :+919870062960
> IIT-Bombay