Abstract
A high-speed design pattern generating method and its hardware for pattern inspection of printed circuit board (PCB) photomasks are described.
PCB photomask patterns consist of some ten kinds of aperture patterns and straight and arc lines by scanning the aperture. Remarking that these patterns are categorized into aperture stop parts and its transfer parts, we developed a new method which generates aperture stop parts by referring stored pattern elements in memories and the transfer parts by high-speed approximation of straight and arc lines.
64 digital signal processors (DSPs) calculate start and end addresses of each pattern in each scanning line in parallel, but in preceding to each raster scanning of a linear image sensor for photomask pattern detection. Input/output buffers of the DSPs are owned commonly and equal services are realized by patrolling to detect requests from each DSP.
Pattern generating speed as fast as 0.1μs/pixel has been achieved. 220 pattern elements can be generated in a scanning line in maximum. Scale of the hardware of this parallel, asynchronous pattern generator is about a half of conventional synchronous ones.
