Double patterning (DP) is widely regarded as the lithography solution for 32 nm half pitch semiconductor manufacturing, and DP will be the most likely litho technology for the 22 nm node [1]. When using the DP technique, overlay accuracy and CD control are of critical importance [2]. We previously introduced the NSR-S620D immersion scanner, which provides 2 nm overlay capabilities. In the case of the latest generation NSR-S621D system, improvements have been developed for further overlay accuracy enhancement. In this paper, we will show the overlay accuracy and Mix-and-Match performance of the NSR-S621D. Further, the marked improvement in product overlay and the overlay result in Spacer DP as a result of enhanced alignment accuracy will also be shown.
