ASML tweaks immersion tool to improve imaging, overlay

July 13, 2011 – ASML has added three extensions to its Twinscan NXT 1950i immersion lithography tool, to improve imaging, overlay, and system throughput.

Just as the company’s FlexRay freeform illumination system (released at SEMICON West in 2009) offers better tuning of the source, so a new FlexWave technology allows application-specific wavefront correction within the lens, offering control to reduce both aberration fingerprint of the projection optics and lens heating effects.

Also, to compensate for reticle heating typically found in high dose layers with low transmission reticles, a new Reticle Control technology incorporates a sensor to measure reticle temperature profile through the first production lot, then predict thermal expansion per exposure, and calculate feed-forward corrections to lens and stage parameters.

Thirdly, ASML is offering a "performance enhancement package" (PEP) of hardware and software upgrades — faster metrology cycle, stiffer position module, and immersion hood to improve dynamic and thermal behaviors for faster speed scans — that it says improves throughput from 175 wafers/hour to 200 WPH at 125 shots, and up to 230 WPH at 96 shots.

All are available as field upgrades, and are available now or will be later this quarter.


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