Technological Development of Advanced Asymmetric Magnetic Soft Mold Micro-Imprint Lithography

Abstract

This study proposed an advanced micro-imprint lithography (MIL), which integrates electromagnetic field-aided hot embossing and PDMS asymmetric magnetic flexible soft mold imprinting techniques, to imprint and replicate the microlens array structure. It is similar to the continuous grayscale technique; however, it is smoother than the structural form defined by the semi-conductor grayscale mask technique, and the process is simpler with lower costs, making it a good alternative for imprinting techniques and applications. This study also employed prescale films to measure and discuss the distribution of imprinting force on asymmetric magnetic soft molds. The results indicated that the magnetic soft mold and the substrate surface can be fully contacted. Since the magnetic powder reveals a skewed distribution, the test results of prescale film indicated that color depth is related to the concavo-convex of magnetic powder. Thus, the depth and accuracy of structural molding can be controlled in advance by casting the inclining platform. Finally, the SEM observation showed that if an inclining platform is used for composite magnetic PDMS casting, the microlens array asymmetric magnetic soft mold structure, which is complementary to it, could be obtained. The asymmetric magnetic soft mold was applied together with electromagnetic field-aided hot embossing equipment to imprint and replicate different continuous and smooth microlens array structures with foreseeable depth.