摘要
This letter reports record-breaking low defect counts for immersion lithography, the mechanism for formation of particle-printing defects, and for two new exposure routings to achieve the low defect counts. Both new routings make the slot-scan directions parallel to the field-stepping directions, whereas in the normal routing the two directions are perpendicular to each other. From experimental data, the average defect count for one of the special routings is 4.8 per wafer, while it is 19.7 per wafer for normal routing. © 2007 Society of Photo-Optical Instrumentation Engineers.