ASML Presents Faster ArF Scanner, Says EUV on Track for 2010
ASML said it is on schedule for 2010 delivery of its first EUV production system. At a research review meeting in Veldhoven, ASML introduced a new positioning measurement system to improve overlay control by 50% to <2 nm for a Twinscan immersion system.
Laura Peters, Editor-in-Chief -- Semiconductor International, 10/20/2008 7:44:00 AM
At a research review meeting in Veldhoven, Netherlands, ASML introduced a Twinscan immersion system that offers significant improvements in performance and productivity relative to previous scanners. Through a combination of faster stage technology and much lighter materials, the company said throughputs of >200 wph are possible.
As device makers begin to require new double patterning techniques for 3X nm device patterning, the specification for overlay accuracy has become more than twice as tight as it is for single-exposure processing. The Twinscan NXT uses a new positioning measurement system to improve overlay control by 50% to <2 nm. In going from single exposure to double exposure, CD uniformity must be halved.
As with previous systems, the scanner uses one stage for alignment and construction of the focus map while the second wafer is being exposed on the second chuck. The measurement and exposure methods both had to be improved to deliver overall throughput improvements. The swap time between the two wafers was ~3 sec on previous platforms. With the new swapping method, the NXT reduces this time drastically.
In addition, using higher rates of acceleration, wafer stepping times are reduced, improving productivity overall by 30%. Acceleration rates on the system are 88 m/sec2 at the reticle level, but this is scaled at the wafer level due to the 4× image reduction. An ASML spokesman said that at the 32 and 22 nm nodes, subtle phenomena such as global deformation of the wafer now need to be compensated for.
The installed base of Twinscan systems is almost 900 tools.
At the research meeting, ASML executives also provided an update on the status of the company’s EUV technology, which has been in evaluation at IMEC (Leuven, Belgium) and Albany NanoTech (Albany, N.Y.). They said the company is on schedule for 2010 first production system delivery. Interestingly, many of the advances on the NXT immersion scanner stage were developed for EUV as well.
The most important, necessary developments for EUV by 2010 include ramping up of the source power to ~100 W to allow throughputs in the 100 wph regime. Current throughput is ~4 wph as reported by IMEC. Technology advances for keeping the EUV reticles clean when they are not in the vacuum environment of the scanner must also be developed. Finally, photoresists for EUV are critical, but in the past several months materials suppliers have apparently made significant advancements.
