Chitosan as a Water-Developable 193 nm Photoresist for Green Photolithography

The development of environmentally friendly materials and processes is a major issue that concerns all industrial sectors, including microelectronics. The aim of this study is to demonstrate the possibility of using chitosan-based photoresists for microelectronic applications on silicon by 193 nm photolithography. The photopatterning of chitosan films is demonstrated and analyzed by different spectroscopy and microscopy techniques. In particular, it is shown that 193 nm irradiation allows one to induce chain breaks that modify the solubility of chitosan in an aqueous developing solution, without denaturing the chitosan macromolecule chains. This mechanism allows one to obtain patterns, and it is shown that these patterns can be transferred by physical etching into silica. It is also demonstrated that the formulated resins are compatible with industrial spin-coating and exposure tools, which opens very interesting perspectives for these chitosan-based positive resins in a microelectronic context.