Fabrication of 3D micro structure by dual diffuser lithography

Abstract

Recently, products that a have 3-dimensional(3D) micro structure have been in wide use. To fabricate these 3Dmicro structures, several methods, such as stereo lithography, reflow process, and diffuser lithography, have been used. However,these methods are either very complicated, have limitations in terms of patterns dimensions or need expensive components. Toovercome these limitations, we fabricated various 3D micro structures in one step using a pair of diffusers that diffract theincident beam of UV light at wide angles. In the experiment, we used positive photoresist to coat the Si substrate. A pair ofdiffusers(ground glass diffuser, opal glass diffuser) with Gaussian and Lambertian scattering was placed above the photomaskin the passage of UV light in the photolithography equipment. The incident rays of UV light diffracted twice at wider angleswhile passing through the diffusers. After exposure, the photoresist was developed fabricating the desired 3D micro structure.These micro structures were analyzed using FE-SEM and 3D-profiler data. As a result, this dual diffuser lithography(DDL)technique enabled us to fabricate various microstructures with different dimensions by just changing the combination ofdiffusers, making this technology an efficient alternative to other complex techniques.