Application of 3D gray mask for the fabrication of curved SU-8 structures

Abstract

This paper proposes a novel technology to fabricate 3D structures such as curved structures on SU-8 resist by 3D gray mask combined with glycerol compensation technique. 3D Gray mask is designed and fabricated by patterning and reflowing AZ4620 resist on standard quartz or glass mask plate. Through exposure dose control, curved shapes with different curvatures have been successfully fabricated with smooth structure surface. Simple calculations on the prediction of the shapes and sizes of the exposed 3-D structures have also been carried out, and the results show a close relationship between the calculations and the experiments. Compared to traditional gray mask technologies, this method provides a simple and cost effective way to fabricate curved structures with reasonable surface smoothness, which may be suitable for optical or micro fluidic applications.