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Line stitching in servo-assisted electron beam lithography system

Maskless electron beam direct write lithography gains more and more attention in the candidates of next-generation lithography technologies. Pattern-placement inaccuracy is a challenging topic which is vital for seamless pattern generation. In this work, a high-resolution piezo-actuated nano stage is integrated into a commercial scanning electron microscope and cooperates with a two-axis coarse stage. Three-axis laser interferometer system is setup in surrounding of the vacuum chamber to establish a global positioning scale of the composite wafer stage. Feedback control is achieved by PID controllers which are implemented in a digital control system. Coupling of the multi-axis piezo-stage is shown, and the performance of the PID controllers is also demonstrated. Stitching of sub-micron line-type pattern over millimeter-range areas is demonstrated.