Cost-effective pattern generation for 64-Mb and 256-Mb photomasks

Abstract

The specifications of reticles for 64 Mb and 256 Mb DRAMs (0.35 tmand 0.25 im design rules)show that the use of leading edge pattern generators is not required for all levels. By using writers optimized for the requirements of each level a lower total cost can be achieved. A laser reticle writer will be described that can be used together with a leading edge system in a mix and match mode.