Design of freeform lens with TFMG reflector for UV-LEDs lithography system

A freeform lens with inclined reflector coated with Al-Ni-Y thin film metallic glass (TFMG) was proposed to improve the irradiance and uniformity of an ultraviolet light-emitting diode (UV-LEDs) lithography system. Polydimethylsiloxane (PDMS) was adopted as lens materials. The lens mold was fabricated by 3-D printing method. Besides, a recipe of TFMG with 88% reflectivity was determined to enhance the exposure performance. The results show the average irradiance and uniformity with 60° inclined reflector were 8.7 mW/cm2 and 82%, respectively. The system with 60° inclined reflector layer can achieve 97.5% average normalized cross correlation (NCC) between the simulation and experimental measurement.