Process design and profile analysis of dual-curvature with dual-focus of microlens array

摘要

This study aims to investigate the morphology of a dual-curvature with dual-focus microlens array by two different lithography processes. First, a diffuser lithography was used to fabricate the bottom of the lens. The result showed that the use of diffuser lithography increases the diameter of the bottom lens 20%. Then a copper layer was deposited on its surface, it is used for alignment in second lithography process. Second, the upper microlens was produced through second lithography process and followed by thermal reflow. The upper microlens formation was calculated by the volume transformation of the column into sphere in thermal reflow process. The pattern diameter of bottom mask had been designed to 100 and 120??m and the upper mask with pattern diameter were 75 and 90 ??m. The bottom microlens were fabricated in JSR-126N, a negative photoresist because of its high melting point when the upper layer fabrication would not affect the morphology of the bottom layer. Two pattern design dual-curvature microlens arrays are successfully produced using the proposed techniques. The related profiles are measured using a confocal laser scanning microscopy to verify their profiles.