Ultra-high Productivity Dry Steppers and Scanners: The “Work Horses” of the Fab

Although there is a great deal of industry focus on immersion lithography at 45 nm and beyond, the bulk of IC manufacturing today is actually occurring at larger geometries using “dry” steppers and scanners. While these litho systems may have less critical imaging requirements, they must still deliver stringent overlay accuracy to meet layer specifications; as well as ultra-high productivity and uptime to ensure optimal cost of ownership (CoO).

Nikon developed the dry KrF NSR-S210D (NA=0.82) and ArF NSR-S310F (NA=0.92) scanners utilizing our proprietary Tandem Stage design to deliver maximum throughput, superior accuracy, and enhanced long-term scanner stability. The S210D delivers more than 176 wafers per hour (S310F ≥ 174 wph) through a combination of increased wafer stage speed (600 mm/sec), a faster reticle stage, and reduced alignment time. In addition to providing dramatic throughput advantages, the Tandem Stage also reduces wafer processing variability to optimize accuracy and stability. The Tandem design uses only one stage for wafer exposure, thereby eliminating any stage mismatching error and enabling frequent calibrations to enhance overlay performance and stability over time. Coupled with improved interferometry and optimized airflow at the wafer stage, these features enable the S310F to deliver overlay accuracy well below 7 nm, with the S210D at less than 9 nm, to satisfy the most aggressive dry single patterning lithography requirements.

Figure 1. The S210D delivers overlay accuracy well below 9 nm (left image). S310F and S210D systems are operating in leading-edge facilities worldwide, processing > 2700 wafers per day with uptime consistently better than 97%.

When combined with excellent uptime, ease of maintenance, and the extensive use of auto-calibration functions, the S210D and S310F have significantly lower cost of ownership compared to scanners from other manufacturers. In addition, Nikon lens technology ensures superior quality and stability over an extended period of time, providing further CoO benefits. Customers recognize the superior value and performance of these products, and NSR-S310F and S210D systems are operating in leading-edge manufacturing facilities worldwide, processing more than 2700 wafers per day with uptime consistently better than 97%. As further validation of customer satisfaction with these systems, the S310F was recently chosen as the Wafer Processing FEOL winner in the 2009 EuroAsia IC Industry Award competition at SEMICON Europa.

Cost-effective i-line lithography equipment is also imperative to a fab’s success. Nikon has delivered several hundred scan field (SF) steppers since their introduction in 2000, steadily reducing i-line cost of ownership with each stepper generation. Continuous design innovations, including increased alignment processing speed and minimized stage settling time, enable the seventh generation SF stepper, the NSR-SF155, to deliver 200 or more wafers per hour (300 mm). The NSR-SF155 incorporates Nikon Skyhook Technology where the lens module is suspended from the main body, eliminating the influence of ground or stage vibration on the lens and associated metrology. This was combined with optimized temperature stabilization in the SF155 chamber and the use of newly-developed heat countermeasures to enable exceptional overlay accuracy for i-line layers. Currently, NSR-SF155 systems are being used globally to process more than 4400 wafers per day, with uptime averaging 99%, while delivering overlay well below 25 nm.

Figure 2. NSR-SF155 systems are being used globally to process more than 4400 wafers per day, with uptime averaging 99% (left image), while delivering overlay accuracy well below 25 nm.

Today’s industry climate is extremely challenging. With the vast majority of IC manufacturing occurring on “dry” steppers and scanners, ultra-high productivity systems delivering optimal overlay accuracy such as the NSR-S310F, S210D and SF155 are essential to achieving your production goals with the lowest cost of ownership.