Development of a microlens array (MLA) for maskless photolithography application

A microlens array (MLA) was developed based on isotropic wet etching of quartz and coating of polymer on the etched substrate for maskless lithography application. Through the optimized manufacturing procedures, uniform elements, excellent light focusing ability, and dense fill factor were obtained. The fabricated MLA has the focal length ranging from 32.2 to 45.4 μm depending on the etching time and the thickness of the coated polymer. The collimated light was uniformly focused on the whole focal plane after passing through the fabricated array of microlenses and the size of the each focused beam was ~1.5 μm. By using the compact imaging ability of the miniaturized lenses, the MLA was applied to UV photolithography process. The illuminated UV passing the MLA focused on the photoresist, producing micron scale pattern array. Various sizes and shapes of micropattern arrays were realized onto the PR via controlling the experimental variables. Even at high temperature, the MLA performances were not changed indicating thermal stability of the developed MLA.