Current status of SR stepper development

We describe some results of exposure experiments using the present prototype SR stepper which Canon has developed and also describe the novel technology development which is necessary to establish the next generation SR stepper for volume production. In the evaluation of the prototype machine, alignment performance, stage accuracy, and printing performance were examined, and we found the SR lithography can be applied to manufacturing devices beyond 0.15 mu m level. In the technology development for the production machine, we have examined methods related to masks: they are reduction of thermal expansion, suppression out-of-plane displacement of mask membrane, and magnification correction. As a result of the examinations, we have a good perspective in development of a high-throughput SR stepper which is suitable for the production beyond 1G-bit DRAM.