All chemical protective mask elaboration for the precise formation of porous silicon
Résumé
We describe “all-chemical” mask structuring methods for the precise formation of porous silicon layers. Those methods aim to compete with the standard masking method for the design of large patterns but also seek to overcome the limit of minimal aperture reached with classical photolithography process. For these purposes, we selected a HF-resistant and widespread polymer: the polystyrene. Two strategies have been developed: the photosensitization and structuration of polystyrene in order to localize porous silicon regions of several micrometres or even millimetres without plasma step and, secondly, the elabora-tion of submicrometric designs by solvent evaporation induced phase separation (SEIPS) in a polymer blend for the con-strained formation of porous silicon. Electrochemical etching of silicon through the mask openings was attempted to evaluate their chemical and mechanical stability.