Long road still to e-beam direct-write litho

Direct-write support
Toppan is a member of the E-Beam Initiative. Kalk said Toppan recognizes that for some chips that do not sell huge volumes, a full mask set can be cost-prohibitive. Toppan supports e-beam direct-write in the hopes that it will eventually enable companies doing lower-volume designs to do critical layers using direct-write while continuing to purchase photomasks for the non-critical layers, which are less expensive but still the majority of a design, Kalk said.

"We see direct-write as keeping open an application space that is going to close," Kalk said.

At SPIE, the E-Beam Initiative announced the additional of six companies, bringing the total number of members in the consortium to 26. D2S, the managing sponsor of the group, appears to be one of the companies following Ronse's advice to apply direct-write technology to mask writing. The company announced at SPIE a new design for e-beam mask technology for the production of advanced optical photomasks with circular and curvilinear shapes, which the company said could help extend 193nm immersion to the 22nm node.

Another company that is doing as Ronse suggests is IMS. In a keynote presentation at SPIE, Elmar Platzgummer, chief operating officer at IMS, said the company built two proof-of-concept tools last year and is continuing to develop its Projection Mask-Less Lithography (PLM2) technology, with a goal of building systems that offer 256,000 programmable electron multi-beams of 50keV energy. But IMS is also developing the electron-optical column of a mask exposure tool for writing leading-edge, complex masks. The company's eMET technology targets the 16nm node and below.

During a paper presentation, Christof Klein, a project manager at IMS, said the company's maskless technology should benefit from the knowledge being gained on the mask exposure tool. Klein said IMS is working on the mask exposure tool "very intently."

Platzgummer said IMS has achieved good results in resolution, but acknowledged that throughput remains too slow. Writing a single 300mm wafer at 60nm half pitch still takes 20 hours, he said.

Mapper Lithography, meanwhile, is not applying its multiple e-beam technology to mask writing. The company said last week that one of its tools, located at Taiwan Semiconductor Manufacturing Co. Ltd's Fab 12 in Hsinchu, Taiwan, is printing features so far unachievable with current immersion lithography technology.

In another paper presentation, Bert Jan Kampherbeek a co-founder of Mapper and vice VP of sales and marketing, said Mapper shipped two "pre-alpha tools" last summer—one to TSMC and one to French technology research organization CEA-Leti.

Kampherbeek said Mapper has shown progress on resolution, including exposure of 20nm SRAM cells. The company is currently focusing on increasing the throughput of its tools, including adding a moveable stage, Kampherbeek said. Mapper hopes to establish a throughput for its tools of 10 wafers per hour and then cluster 10 tools together in a system that can write 100 wafers per hour.

Mapper's tools feature 110 electron beams that can be individually switched on and off by means of an optical blanker array.

- Dylan McGrath
EE Times

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