Design of a force-decoupled compound parallel alignment stage for high-resolution imprint lithography

Parallel surface contact between the template and the substrate is very important in imprint lithography. In this paper, a novel force-decoupled compound parallel alignment stage is proposed for high-resolution imprint lithography. It mainly consists of a high-stiffness spherical air bearing (SAB) and a multi-degree-of-freedom (multi-DOF) flexure-based mechanism that functions for both the active and passive alignments. Apart from the function of the parallel alignment, the proposed stage can also endure a large imprinting force of more than 1000 N but does not cause any damage to the delicate components, which is mainly attributed to its force-decoupled characteristic. Through the stiffness modeling and finite element analysis (FEA), the performance is evaluated to satisfy the design requirement. Finally, experimental tests are conducted on the parallel alignment stage for the hot embossing process, and the grating patterns with linewidth of 2.5 μm are successfully transferred from the silicon template to the polymethy methacrylate (PMMA) substrate. This result demonstrates that the proposed stage can be used in the hot embossing process without degrading its alignment accuracy.