Optics optimization of 10µm resolution used for the smart phone's PCB and ITO lithography

Abstract

Aimed at 10μm resolution used for the smart phone's PCB and ITO lithography, an optical system based on 351 nm XeF excimer laser projection and scanning is designed. The optimized parameters such as maximum optical path difference, depth of focus (DOF), maximum field curvature and distortion, etc. is obtained by experiment and analysis. For the laser projection lithography system used to directly achieve patterning with higher resolutions as well as higher throughput, the projection lens for a unit-magnification is tentatively simulation-designed using ZEMAX optical design software. The optimized design results meet the demands in technical specifications. For the sake of optimizing the paraxial plane in the length of the DOF, a new aligning way is used to get the optimum figure of the developed substrates through a microscope. The results can be used to figure out the shortest path to the focal plane. By testing, the alignment precision is 2μm, adjustable range 2mm in the optical axis. This helps us obtain dependable theoretical evidence for our projection exposure system to align the substrate and the mask. All experiments demonstrate that this optimized system can satisfy the 10μm resolution lithography.