Long road still to e-beam direct-write litho

While multiple development efforts focused on e-beam direct-write lithography have reported progress, a one prominent lithography researcher claims production tools are still a minimum of five years away.

Based on the length of time it has historically taken for each new lithography technology to move from proof-of-concept to production, e-beam direct-write lithography tools will be available no sooner than 2015, according to Kurt Ronse, lithography department director at nanoelectronics research center IMEC.

Ronse offered some advice to the many companies and consortiums developing e-beam direct write technology: target the 16nm node, because the technology won't be commercially viable by the 22nm node—the target of many of the development efforts.

Ronse also recommended that these groups initially apply their technology to mask-writing tools—where throughput requirement would not be so arduous—as a shorter term, intermediate step.

Chip makers continue to look longingly at direct-write lithography, which could potentially reduce or remove the need for photomasks, which are getting more expensive—according to data presented by Ronse, the cost of a mask set doubles at each new technology node. Analysts and industry executives label the rising cost of masks as the chief culprit behind an ominous trend: declining ASIC starts.

But technical issues—including unacceptably slow wafer writing times—have to date kept e-beam direct write lithography from moving closer to commercial production.

Providing an overview of the latest direct-write development work being done by three European-based companies, Ronse said the resolution of tools is getting closer to acceptable range for the 22- and 16nm nodes, but that overlay control and throughput remain well short of what is needed.

"It's a very interesting technology, and I have a lot of respect for the people developing it," Ronse said. "But in terms of overlay and throughput I think there is a long way to go."

A number of firms and consortiums that are developing e-beam direct write technologies gave presentations at SPIE, including Mapper Lithography BV, IMS Nanofabrication AG and the eBeam Initiative, a consortium of more than 25 companies headed by Direct2Silicon Inc. Others are also developing e-beam direct-write technologies, including KLA-Tencor Corp., Micronic Laser Systems AB, Vistec Electron Beam Lithography Group and Tokyo Electronic Ltd, in addition to government-backed research and universities.

That there remain so many distinct direct-write development efforts is testament to the technology's potential market opportunity. Anyone who can bring to production an e-beam direct-write lithography technology stands to cash in, particularly in light of next-generation extreme ultraviolet (EUV) lithography being pushed out further to target production at the 16nm node. This means lithographers will push 193nm immersion lithography down to at least 22nm, but there is widespread consensus that that technology is not extendible to the 11nm node.

"I don't want to say that we are desperate, but when the industry is on the cusp of a major change, you are going to see all of these new technologies emerge," said Franklin Kalk, executive VP and chief technology officer Toppan Photomasks Inc.