Focused laser lithographic system for efficient and cross-scale fabrication of large-area and 3D micro-patterns

A novel focused laser lithographic system with a low-power ultraviolet laser, a high-speed galvanometer scanner and a customized F-theta lens was constructed and demonstrated for cross-scale, high-efficiency and low-cost fabrication of large-area micro-patterns. In this system, a high-speed galvanometer scanner was used for the first time to greatly improve lithographic efficiency. The optical path was optimized and studied in detail, and the distortions caused by the scanners and F-theta lens were explained with mathematical expressions. Then, a method of correction chart was employed to further reduce the distortion and stitching error. The effect of laser parameters on linewidth of the fabricated micro-patterns was investigated and optimized. The significance sequence of these parameters was laser power, scan time, scan speed and defocus, and the optimal line width/space was below 10 µm. After the optimization, a 150 mm × 150 mm gridding with 9.8 µm linewidth and 90 µm line space was fabricated within 300 s, and the stitching error was less than 10%. To demonstrate the ability for arbitrary micro-patterns fabrication, a 150 mm × 120 mm HUST logo with the feature size of about 10 µm was fabricated within 40 s. Array circular holes with the feature size of below 10 µm were also obtained with a scan speed of 2000 mm/s. Using this system, cross-scale and large-area micro-patterns could be fabricated conveniently with high efficiency and less stitching error. With the assistance of z stage, the system can also realize three-dimension (3D) micro-fabrication.