Green deep-UV photoresist based on chitosan for microelectronics

Abstract

Photolithography is a core part in microelectronic processes. This technological step implies the use of numerous hazardous carcinogenic compounds in the formulations, the use of solvents for processing synthetic polymers to obtain micro and nanostructures. We proposed the use of chitosan-based biosourced water-soluble resins to significantly reduce the environmental impact of the photolithography step, for 193 nm photolithography. We show in this report that chitosan-based photoresist is suitable for microelectronic application, and in particular, we could significantly improve photosensitivity by adding a water-soluble photoacid generator (PAG). UV–visible and Fourier transform infrared-attenuated total reflectance characterizations reveal an increase of the macromolecular chain scission kinetics in the presence of PAG. Moreover, the local decrease of the pH favors the solubility of chitosan in irradiated areas. Finally, the photolithography tests demonstrate that the dose to clear and the optimal dose for photopatterning are divided by a factor of two. Moreover, the physical etching transfer tests show that the presence of PAG does not decrease the transfer performance, making these aqueous-based formulated resins still more adapted for the fabrication of microelectronic devices.