High precision laser machining circuit generator

Abstract

An accuracy of ±0.25 μ has been achieved in the generation of patterns with features of 3.0 μ and gaps of 2.8 μ in metallic thin films on glass. Patterns are generated by using a raster scan motion in combination with a laser beam for machining. The positioning system consists of a stepping table capable of 0.5±0.1 μ steps over a 2 cm range in the y direction and a shuttle table capable of 0.5 m/sec constant velocity over a distance of 10 cm in the x direction. The position of the stepping table depends on the accuracy of a ball lead screw, and the position of the shuttle table is monitored by a laser interferometer whose information is used to control the laser modulation. The stepping table carries the focusing lens for the laser beam and the shuttle table carries the substrate. Laser machined spots 2 μ diam are made using a highly stable Nd-YAG cavity dump laser operating at 0.5 MHz in the TEM00 mode. The address structure for the pattern is 0.95 μ in the x direction and 1.0 μ in the y direction. A computer control system will make it possible to process up to four 1 cm × 1 cm substrates simultaneously, with a total machining time of 36 min. At present, patterns are generated using a control system comprised of a 32-bit programmable word generator for the x direction and a 63-bit counter for the y direction.