I would highly recommend using SU-8 for your SF6 process. We have developed a
silicon etch and the selectivities with SU-8 vs. positive thicker resists is
much higher. We do not do the second bake and keep the temperature of the resist
low during processing so cross-linking is not a problem. In fact we ash it off
in the same chamber when we are through with the DRIE silicon etch. Bob
Henderson