If you use a non-multiplexed etch with an etchant containing sufficient carbon, a polymer will be left on the sidewalls. This will happen, for example, with equal parts of SF6, CHF3 and O2. Roger Shile -----Original Message----- Hi all, Does anyone know any etchant that will etch Silicon alone leaving Teflon like fluoropolymer which we get from the passivation stage of bosch process? Thanks in advance! Arun