Deep plasma etching of Parylene C patterns for biomedical applications

We report on the plasma etching of thick Parylene C (~25 µm) in order to define flexible implantable probes for neural applications. Parylene C is a transparent polymer that presents with high biocompatibility, flexibility and chemical inertness, and has gained increased attention over the years in the biomedical field. In the manufacturing process, highly defined structuration steps of Parylene C are essential, but techniques based on laser, scalpel and wet etching have shown to be unsuitable for properly cut structures, i.e. with good dimensions control and without residues. Here, for the first time, negative resist (BPN) coating followed by RIE-ICP are used in order to pattern Parylene C-based structures, with a clean cut, vertical profile, fast etching rate (~0.8 µm/min) and conservation of device biocompatibility