Fabrication of microlens arrays based on the mass transport effect of SU-8 photoresist using a multiexposure two-beam interference technique

Abstract

Microlens arrays (MLAs) were fabricated based on the mass transport effect of SU-8 photoresist by a multiexposure two-beam interference technique. In particular, a direct single-step fabrication process, i.e., without developing, mask, and pattern transferring processes, is demonstrated. The effects of various parameters such as thicknesses, exposure dosage, and angle between two laser beams on MLAs were investigated. Square and hexagonal lattices of microlenses were obtained by controlling rotation angles between different exposures on SU-8 samples. In addition, microlenses with elliptical shape were fabricated by a double exposure at 0 degrees and 60 degrees. Finally, the surface profiles of microlenses in MLAs were characterized by atomic force microscopy.