Optimum design of a 740 mm-long lens mount for a large-area and high-speed line beam proximity exposure

Abstract

Proximity exposure with line beam scanning can be an alternative to traditional proximity exposure for a fast, high-resolution, large-area patterning. The optical elements used for shaping the line beams have a very large length-to-cross-sectional area ratio, so even small misalignment has a large effect on the optical path. In this study, a lens mount system based on kinematic coupling was established to accurately locate and align the line beam lens. Finite element models of the line beam lens and the mount were constructed, and then static structural simulations were performed. Optical paths concerning lens deformation and misalignment were calculated based on the vector equations for lines, surfaces, and Snell's law. An optimum design process based on the Taguchi method was carried out to minimize the difference between the actual optical arrival location and the target location. The stiffness and clamping force of the clamp part and support positions were selected as design variables, and the geometrical uncertainties of the lens supports was treated as error factors. A cross product array was constructed for each design variable and error factor, and then a total of 36 simulations were performed. Finally, the influence of each design variable on the optical path was analyzed, and the optimum conditions for the design variables, minimizing the error factor, were determined. As a result, the optical path error due to the geometrical uncertainty was reduced by approximately 30% compared to initial design.