Impact of process parameters on the flow behavior and filling accuracy of photoresist in hot embossing for microgroove array

Hot embossing is a cost-effective and efficient method for fabricating micro-nano structures. However, challenges arise from the flow behavior and rebound phenomena of photoresists during hot embossing, leading to issues with filling accuracy and subsequently degrading optical properties. Therefore, elucidating the impact of process parameters on filling accuracy in hot embossing is crucial. Initially, a polydimethylsiloxane (PDMS) soft mold was fabricated by replicating microgroove arrays from a nickel-phosphorus (Ni-P) mold, which was produced using ultra-precision fly-cutting techniques. Subsequently, the microgroove morphology from the PDMS soft mold was transferred onto the photoresist surface through hot embossing. A numerical model for photoresist filling accuracy was established and experimentally validated. The filling mechanism of photoresist in hot embossing was elucidated. Polymer viscoelasticity decreased with increasing temperature, substantially enhancing filling accuracy, followed by a gradual decrease due to rebound phenomena. Additionally, higher embossing forces enhanced the filling ratio, but excessive pressure led to the deformation of the soft mold. Process parameters were optimized through numerical simulation and experimentation, achieving processing errors at the hundred-nanometer level and a filling ratio of 97.3 %.