Development and applications of a laser writing lithography system for maskless patterning

A laser writing lithography system is developed based on the 325-nm UV radiation of a helium-cadmium laser. A custom-built optical system with a modified microscope and computerized exposure and motion stages are the other main components of the system. The lithography system is able to process data input from industry-standard Caltech intermediate form (CIF) graphic files. We achieve a minimum linewidth resolution of 1.6 μm on a positive photoresist-coated silicon substrate written with a 10x UV objective lens of numerical aperture 0.20. Other processing parameters, such as the optimal writing speed and the amount of overlap for pattern generation, are also determined. Application of the laser lithography system is also demonstrated in the fabrication of a UV-detecting metal-semiconductor-metal diamond thin film photodetector and in the direct delineation of polythiophene polymer film.