For 32 nm half-pitch node, double patterning is recognized as the most promising technology since some significant
obstacles still remain in EUV in terms of technology and cost. This means much higher productivity and overlay
performance will be required for lithography tools. This paper shows the technical features of Nikon's new immersion
tool, NSR-S620 based on newly developed platform "StreamlignTM" designed for 2nm overlay, 200wph throughput and
2week setup time.
The S620 is built basically upon Nikon's Tandem Stage and Local Fill Nozzle technology, but has several additional
features. For excellent overlay, laser encoders with short optical path are applied for wafer stage measurement in
addition to interferometers. By using this hybrid metrology, the non-linearity of the encoder scale can be easily
calibrated, while eliminating the air fluctuation error of interferometer. For high throughput, a method with a new
alignment microscope system and a new auto focus mapping, called Stream Alignment is introduced. It makes it possible
to reduce the overhead time between the exposures remarkably. The target productivity is 4,000 wafer outs per day.
Accuracy is also improved because many more alignment points and a continuous wafer height map without stitching are
available. Higher acceleration and faster scan velocity of the stages are also achieved by optimal vibration dynamics
design and new control system. The main body, including the projection lens, is isolated by Sky Hook Technology used
already on the NSR-SF150 and SF155 steppers, and also the reticle stage is mechanically isolated from the main body.
With this new platform, the imaging performance can be maximized.