SAN JOSE, Calif. – IBM reported better than expected results on its first full day of testing the latest ASML extreme ultraviolet (EUV) lithography system. The NXE3300B scanner produced 637 wafers in 24 hours at a steady rate of 34 wafers/hour with a light source delivering 44W.
EUV is the leading candidate for printing fine patterns needed for next generation chips. But the complex technology has been in the lab for more than a decade. Even with IBM's latest results, it is still not expected to be ready until the 7nm node, which may not start production until nearly 2020.
In its first day of tests, the scanner at IBM's Albany, N.Y., research lab had a 77% uptime and delivered a 20mJ dose across 83 image fields/wafer with full wafer coverage, including partial die. "We did have some interrupts along the way, otherwise we would have produced more than 800 wafers in a day," said Dan Corliss, IBM's EUV development program manager.
Corliss's team has been working on calibrating the scanner for two months. It was delivered in components starting last November, initially with a 25W light source.
The relatively weak light source has been one of the top challenges of EUV systems, holding back throughput of at least 100 wafers/hour needed for high volume manufacturing. Corliss said IBM hopes to get an 80W light source from ASML in about six month
IBM's previous EUV system only exposed 7 wafers/day. ASML recently reported the latest system had throughput of 145 wafers/day.
"We were pleasantly surprised by our results," Corliss said. "We've been working on this technology for 12 years and this is a positive moment to share with the industry... [but] it's not like we are in high-volume manufacturing -- we have a lot of work to get there," he added.
IBM is investigating why the light source is sometimes not available. It is also working on a laundry basket of other issues with EUV including mask defects.
ASML reported at Semicon West it is developing a pellicle, a kind of filter used in today's immersion scanners. That's been high on the wish list for chip makers for some time.
Corliss is taking a wait-and-see stance on the ASML pellicle. "It’s a research project... that’s why we have a parallel infrastructure in place, but the industry would embrace a pellicle if it's available, easy to use, long-lived, and has no impact on image quality," he said.
IBM used partial field exposure, shining EUV light beyond the scope of the 300mm wafer in its initial tests.
— Rick Merritt, Silicon Valley Bureau Chief, EE Times