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 cross-linked 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.