Low f-Number Microlenses for Integration on Optical Microsystems

摘要

This paper presents microlenses (MLs) with low f-number made of AZ4562 photoresist for integration on optical microsystems. The fabrication process was based on the thermal reflow and rehydration. Large series of MLs were fabricated with a width of 35 mu m, a thickness of 5 mu m, and spaced apart by 3 mu m. The MLs were fabricated directly on the surface of a die with type n+/p-substrate junction photodiode fabricated in a standard CMOS process. The measured focal length was 49 mu m with a tolerance of +/- 2 mu m (maximum error of +/- 4), resulting in a numerical aperture of 33.6 x 10(-2) (+/- 1.3 x 10(-2)). The measurements also revealed an f-number of 1.4.