Immersion and dry ArF scanners enabling 22nm HP production and beyond

Abstract

Pattern shrinks using multiple patterning techniques will continue to the 22nm half pitch (HP) node and beyond. The cutting-edge Nikon NSR-S621D immersion lithography tool, which builds upon the technology advancements of the NSR-S620D [1], was developed to satisfy the aggressive requirements for the 22 nm HP node and subsequent generations. The key design challenge for the S621D was to deliver further improvements to product overlay performance and CD uniformity, while also providing increased productivity. Since many different products are made within an IC manufacturing facility, various wafer process-related issues, including the flatness or grid distortion of the processed wafers and exposure-induced heating had to be addressed. Upgrades and enhancements were made to the S620D hardware and software systems to enable the S621D to minimize these process-related effects and deliver the necessary scanner performance. To enable continued process technology advancements, in addition to pattern shrinks at the most critical layers, resolution for less critical layers must also be improved proportionally. As a result, increased demand for dry ArF instead of KrF scanners is expected for less critical layers, and dry ArF tools are already being employed for some of these applications. Further, multiple patterning techniques, such as sidewall double patterning, actually enable use of dry ArF instead of immersion scanners for some critical layers having relaxed pattern resolution requirements. However, in order for this to be successful, the ArF dry tool must deliver overlay performance that is comparable to the latest generation immersion systems. Understanding these factors, an ArF dry scanner that has excellent overlay performance could be used effectively for critical layers and markedly improve cost of ownership (CoO). Therefore, Nikon has developed the NSR-S320F, a new dry ArF scanner also built upon the proven S620D Streamlign platform. By incorporating the Streamlign innovations, sufficient overlay accuracy for critical layers, as well as maximized productivity can be achieved. Furthermore, CoO will be significantly improved, which is the vital benefit when comparing ArF dry vs. immersion scanners. In this paper / presentation the latest S621D and S320F performance data will be introduced.