Microlithography system for high-resolution large-area patterning on curved surfaces

Abstract

A projection microlithography system that can pattern very large, curved substrates at very high exposure speeds and any desired image resolution, the substrates being permitted to have arbitrary curvature in two dimensions. The substrate is held rigidly on a scanning stage, on which is also mounted a mask containing the pattern to be formed on the substrate. The mask is imaged on the substrate by a projection subsystem which is stationary and situated above the scanning stage. The mask is illuminated with a polygonal illumination beam which causes a patterned region of similar shape to be imaged on the substrate. Different regions of the substrate are moved in a direction parallel to the direction of the optical axis at the substrate (z-axis) by suitable amounts to keep the segment being exposed within the depth of focus of the imaging lens. The stage is programmed to scan the mask and substrate simultaneously across the polygonal regions so as to pattern the whole mask. Suitable overlap between the complementary intensity profiles produced by the polygonal illumination configuration ensures seamless joining of the scans. This microlithography system includes opto-mechanical mechanisms for dynamically sensing the substrate height at each point, for moving the substrate in the z-dimension, and/or configuring the focal plane of the projection subsystem so as to always keep the substrate region being exposed within the depth of focus of the projection subsystem.