Non-Spherical SU-8 Microlens Array Fabricated Utilizing a Novel Stamping Process and an Electro-Static Pulling Method

This paper presents a simple and novel method to fabricate non-spherical SU-8 microlens array utilizing a soft SU-8 stamping approach and an electro-static pulling process. A SU-8 based stamp composed of micro-nozzle arrays and a reservoir structure is first fabricated on a glass substrate using a process of dosage control exposure. The unexposed SU-8 encapsulated in the cross-linked SU-8 shell is used as the "ink" for the stamping process. The presented SU-8 microlens array is then formed by stamping the formed SU-8 structure on an ITO glass substrate at a temperature higher than the glass transition temperature of unexposed SU-8 PR. The formed SU-8 array is then electro-statically pulled in a uniform electric field to generate non-spherical microlenses with various radii of curvature. Microlens arrays with diameters ranging from 20 to 500 mum are successfully fabricated with the presented method. Measured surface roughness (Ra) of 3.84 nm and good optical uniformity confirm the optical quality of the microlens arrays fabricated with this innovative fabrication technique.