Fabrication of ultra-thin laser induced graphene electrodes over negative photoresist on glass for various electronic applications

Abstract

Photoresists play a pivotal role in pattern transfer applications to achieve microstructures with high aspect ratios and vertical sidewalls for MEMS and semiconductor industries. Negative photoresists (NPR) have been leading the photoresist industry ever since their inception with excellent chemical resistance and high thermal and mechanical stability. However, owing to its low conductivity, NPR is restricted only to structural and sacrificial applications. For this first time, this work showcases the utilization of NPR to obtain ultra-thin and highly conductive laser Induced graphene (LIG) over glass substrates through laser ablation. Different combinations of NPR samples were considered at different spin speeds (2000 rpm to 4000 rpm) to obtain various thickness values to comprehend the effect of parameters, such as UV exposure, baking conditions, and photoresist thickness over obtained conductivity of the LIG. It was observed that samples which were coated with NPR at 4000 rpm followed by hard baking without UV exposure exhibited a conductivity of 529.7 S/m upon repeated ablation of laser. The functionality of the fabricated thin film electrodes was tested for biofuel cell and electrochemical applications. The novel method to create conductive patterns over glass substrates not only pave a possible way for realizing glass-based electronic devices but also open up new avenues for microelectronic industry.