|Chip Roadmap Looks Dark, Bumpy|
SAN JOSE, Calif. — The semiconductor roadmap could extend a decade to a 1-nm node or it could falter before the 3-nm node for lack of new resist chemistries. Those were some of the hopes and fears that engineers expressed at an evening panel session at an annual lithography conference here.
The session was intended as a lighthearted send-up of the long-predicted death of Moore’s Law. It also showed the disturbing uncertainties that are natural outgrowths of the many challenges perpetually appearing on the path to next-generation chips.
Today, Samsung has started production of 7-nm devices using extreme ultraviolet lithography. TSMC expects to ramp a 7+-nm node using EUV by June. ASML aims to serve both with a 2019 upgrade of its EUV system, the 3400C, promising throughput of 170 wafers/hour and 90+% availability.
One of the next big challenges is brewing more sensitive resist materials for the 3-nm node. Today’s chemically amplified resists (CARs) “are OK for the current and maybe next generation, but we’d like new platforms,” said Tony Yen, a vice president at ASML.
Yen pointed to the long history of CARs dating back to the 1980s and 248-nm lithography. “It’s about time we put more emphasis in new platforms like molecular resists,” Yen said.
With a total market for the crucial chemicals valued at less than a billion dollars a year, “the model needs to change,” he added. “Development could be done in a pre-competitive place and then licensed to commercial resist vendors.”
Ryan Callahan from resist maker FujiFilm disagreed. “There is great competition to secure the business because those who are first will succeed and others will be gone … [but with the] market getting smaller as some [ such as GlobalFoundries] abandon EUV, resist suppliers won’t do consortia for developing together,” he said.
ASML plans to release this year an upgrade of its current EUV system. Click to enlarge. (Source: ASML)
In an effort to jumpstart work on resists for next-generation EUV systems, imec and laser specialist KMLabs announced that they will form a so-called AttoLab. It will try to characterize how resists absorb and ionize photons in time frames measured in pico- and attoseconds.
“We will learn how to see the fine detail of radiation chemistry, working with suppliers to find new materials to take us to the next level … We will also look at quantum phenomena … it is pure science, but new technologies may come from this work,” said John Petersen, a principal scientist at imec who co-authored papers describing the new lab.
The resists are one way to reduce random errors known as stochastics, an old problem but one raising its head aggressively as engineers push toward the 5-nm node. Yen was bullish that ASML will deal with the defects that threaten yields.
“Stochastics are more severe now than they were with 193-nm lithography, but they can be countered by higher [light] doses,” Yen said. “Our roadmap goes to 500-W systems, so we are going up in power, and High NA systems will deliver a better image quality, so we are well-prepared to combat stochastics.”
Phillipe Leray, a metrology specialist at imec, was less optimistic. “We have to tackle the defect challenge in the near future,” he said. “Time is running out, and I don’t see any solution around the corner.”
Next page: Pulling out all the stops for scaling
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