Optical mask projection method and application in in-situ movement fluctuation measurement of motorized stage

Abstract

The fabrication of optical elements with micro/nano-pattern structures typically relies on high numerical aperture (NA) direct laser lithography systems. The stability of such systems is often influenced by movement fluctuation errors of the motorized stages. In this work, the optical mask projection method has been further studied, and a high-precision movement fluctuation measurement module based on the mask projection method has been developed for high-NA direct laser lithography systems. The theoretical calculations and experimental results demonstrate that the established module achieves a measurement accuracy of ±10 nm in high-NA systems. Through the application of this module, the in-situ movement fluctuation error of the x-y motorized stage in the direct laser writing lithography system was measured. The results showed an average error of ±3.479 μm for 10 mm × 10 mm movement area, and the movement fluctuation error profile was mapped, accordingly. Based on the results, the corrections were carried out to decrease the installation errors of the motorized stage, an optimized average movement error of ±0.554 μm is obtained, which is 84.1% lower than the initial value before optimization. For 50 mm × 50 mm movement area, the measurement results and direct laser lithography results confirmed that the fluctuation error after correction was within the acceptable range. This work is applicable for the measurement and optimization of movement fluctuation errors of motorized stages in high-NA direct laser writing lithography systems.