But in our system, a Plasma-Lab ICP-RIE, we are using the Silicon Nitride as a mask for Cl2/Ar etching....and it doesn't etch much at all. Does you know if CH4 will work? This is with a PMMA etch mask. We suspect fluorine interacts with the underlying materials (not just as etch damage...) so I did want to compare results using a non-fluoring containing etch. Thank you for your suggestion. > >Hi Bill, Cl2 + Ar will work... But depending on why you are >trying to avoid F, Cl may be worse... -Marie