Delivers industry-leading immersion performance and productivity with the proven Streamlign platform
The semiconductor industry is transitioning to development and high volume manufacturing of next-generation process devices, with the most critical layers exposed using ArF immersion scanners with multiple patterning. Therefore, in order to minimize costs, productivity and yield are of essential importance to IC makers. This necessitates immersion scanners that deliver ultra-high productivity and superior overlay accuracy, as well as exceptional system stability and matching capabilities. The NSR-S621D builds upon the Streamlign platform that is already employed globally and delivering optimal cost of ownership for NSR-S620D immersion scanners, and incorporates further hardware and software developments to deliver industry-leading overlay accuracy and throughput. The advanced NSR-S621D immersion scanner fully satisfies the aggressive high volume requirements of 20 nm technology and beyond.
Overlay accuracy ≤ 2 nm and advanced overlay solutions enable superior yield
Interferometers alone cannot sufficiently measure stage position repeatability to satisfy the most stringent immersion overlay requirements. Therefore, the NSR-S621D utilizes the proven Bird's Eye Control system, which uses laser encoders along with conventional interferometers to accurately determine wafer position. In addition, the S621D incorporates a grating plate structure that decreases linearity variation across the wafer stage area to improve stability, while reticle expansion effects are mitigated using a Reticle Cooling System that minimizes thermal deformation of the reticle. These innovations enable overlay accuracy ≤ 2 nm and superior focus control to deliver maximized yield for leading-edge immersion applications. The S621D has demonstrated single machine overlay (SMO) potential below 1 nm, as well as SMO Avg. + 3σ capabilities of x=1.6 and y=1.9 nm across the lot, and SMO error less than 2.5 nm has been maintained across 5 lots.
For heightened matching accuracy, compensation functions that adjust the grid and distortion of one scanner to another are also imperative. The S621D supports advanced shot distortion correction capabilities provided by Dynamic Matching Adjustment Control, with k18 c-shape distortion compensation newly added to enable distortion correction along the scan slit. Actual mix-and-match overlay performance using two S621D systems showed across lot overlay stability below 4.5 nm (Avg. + 3 σ), which fully satisfies production requirements.
Ensures optimal affordability with throughput ≥ 200 wafers per hour
S621D throughput is a critical factor in making these advanced processes cost effective for manufacturing. The NSR-S621D wafer stage uses optimized scan speed and acceleration capabilities to reduce exposure time. In addition, the Stream Alignment wafer mapping system utilizes multiple alignment microscopes (Five-Eye FIA) and a wide area autofocus sensor (Straight Line Autofocus) that spans the wafer to pre-scan the substrate during loading, dramatically reducing overhead time. Together, these innovations enable world-class throughput ≥ 200 wafers per hour (125 exposures).
1.35 NA lens with sophisticated thermal aberration control provides exceptional imaging
The NSR-S621D incorporates an established multi-axial catadioptric lens with a 1.35 numerical aperture to support 20 nm technology and beyond. Advanced lens materials are utilized to reduce thermal absorption, as well as to ensure that aberration and local flare levels are extremely low. The sophisticated Quick Reflex deformable mirror system also enables on-the-fly astigmatism control, while the Reticle Bending function provides correction for lens field curvature and/or curvature differences between reticles, in order to enhance imaging performance.
State-of-the art optical control capabilities increase extendibility
The NSR-S621D is compatible with optional Nikon OPE Master software. OPE Master optimizes imaging parameters to minimize the OPE error between a reference scanner and the one to be adjusted. The user can input pattern information, exposed OPE results, and optimizing parameters for the OPE matching. The S621D works in tandem with OPE Master software to successfully minimize optical proximity errors across the toolset. CD uniformity is also imperative for multiple patterning applications, and S621D across wafer CDU 3σ results of 0.6 nm for inter-field and 0.7 nm for intra-field measurements have been achieved using optional CDU Master software.
Modular design streamlines installation and repairs
Being first to market with new devices can be the difference between profit and loss. To help customers meet this challenge, the S621D incorporates the mature Modular² Structure also used on the NSR-S620D to streamline system installation and minimize time to production. The proven Modular² Structure uses standalone subassemblies to improve system setup, and simplify assembly and maintenance.