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What’s the Next-Gen Litho Tech? Maybe All of Them

By Jeff Dorsch, Contributing Editor

The annual SPIE Advanced Lithography symposium in San Jose, Calif., hasn’t offered a clear winner in the next-generation lithography race. It’s becoming clearer, however, that 193i immersion and extreme-ultraviolet lithography will co-exist in the future, while directed self-assembly, nanoimprint lithography, and maybe even electron-beam direct-write technology will fit into the picture, too.

At the same time, plasma deposition and etching processes are assuming a greater interdependence with 193i, especially when it comes to multiple patterning, such as self-aligned double patterning, self-aligned quadruple patterning, and self-aligned octuple patterning (yes, there is such a thing!).

“We’ve got to go down to the sub-nanometer level,” Richard Gottscho, Lam Research’s executive vice president of global products, said Monday morning in his plenary presentation at the conference. “We must reduce the variability in multiple patterning,” he added.

Gottscho touted the benefits of atomic level processing in continuing to shrink IC dimensions. Atomic level deposition has been in volume production for a decade or more, he noted, and atomic level etching is emerging as an increasingly useful technology.

When it comes to EUV, “it’s a matter of when, not if,” the Lam executive commented. “EUV will be complementary with 193i.”

Anthony Yen, director of nanopatterning technology in the Infrastructure Division of Taiwan Semiconductor Manufacturing, followed Gottscho in the plenary session. “The fat lady hasn’t sung yet, but she’s on the stage,” he said of EUV.

Harry Levinson, senior director of GlobalFoundries, gave the opening plenary presentation, with the topic of “Evolution in the Concentration of Activities in Lithography.” He was asked after his presentation, “When is the end?” Levinson replied, “We’re definitely not going to get sub-atomic.”

With that limit in mind, dozens of papers were presented this week on what may happen before the semiconductor industry hits the sub-atomic wall.

There were seven conferences within the symposium, on specific subjects, along with a day of classes, an interactive poster session, and a two-day exhibition.

The Alternative Lithographic Technologies conference was heavy on directed self-assembly and nanoimprint lithography papers, while also offering glimpses at patterning with tilted ion implantation and multiphoton laser ablation lithography.

“Patterning is the battleground,” said David Fried, Coventor’s chief technology officer, semiconductor, in an interview at the SPIE conference. He described directed self-assembly as “an enabler for optical lithography.”

Mattan Kamon of Coventor presented a paper on Wednesday afternoon on “Virtual fabrication using directed self-assembly for process optimization in a 14nm DRAM node.”

DSA could be used in conjunction with SAQP or LELELELE, according to Fried. While some lithography experts remain leery or skeptical about using DSA in high-volume manufacturing, the Coventor CTO is a proponent of the technology’s potential.

“Unit process models in DSA are not far-fetched,” he said. “I think they’re pretty close.  The challenges of EUV are well understood. DSA challenges are a little less clear. There’s no ‘one solution fits all’ with DSA.” Fried added, “There are places where DSA can still win.”

Franklin Kalk, executive vice president of technology for Toppan Photomasks, is open to the idea of DSA and imprint lithography joining EUV and immersion in the lithography mix. “It will be some combination,” he said in an interview, while adding, “It’s a dog’s breakfast of technologies. Don’t ever count anything out.”

Richard Wise, Lam’s technical managing director in the company’s Patterning, Global Products Groups CTO Office, said EUV, when ready, will likely be complementary with multipatterning for 7 nanometer.

Self-aligning quadruple patterning, for example, was once considered “insanity” in the industry, yet it is a proven production technology now, he said.

While EUV technology is “very focused on one company,” ASML Holding, there is a consensus at SPIE that EUV’s moment is at hand, Wise said. Intel’s endorsement of the technology and dedication to advancing it speaks volumes of EUV’s potential, he asserted.

“Lam’s always excelled in lot-to-lot control,” an area of significant concern, Wise said, especially with all of this week’s talk about process variability.

What will be the final verdict on the future of lithography technology? Stay tuned.

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