Positive resist for UV and X-ray lithography synthesized through sol–gel chemistry

A positive tone resist for UV and X-ray lithography synthesized starting from an organically modified silicon alkoxide, bis(triethoxysilyl)benzene, through the sol–gel method, either in basic or in acid catalysis, is presented. Being directly photo-processable, the sol–gel system combines the opportunity to avoid the use of a sacrificial layer in the fabrication process, with the possibility to fit electro-optical and structural properties of the final device material to specific requirements. In addition, the positive tone behaviour allows to preserve the organic functionality of the system after irradiation. A study of the optical and structural modifications induced on the resist by irradiation has been carried out by FT-IR spectroscopy, UV–vis spectroscopy and spectroscopic ellipsometry. An interpretation of the mechanisms leading to exposed crosslinked film development is given. Experiments have demonstrated the possibility of obtaining structures on films with lateral dimensions spanning from the micron scale up to less than a hundred nm, opening the way to a possible exploitation of such positive tone functional system in the field of miniaturized sensors.