By Jeff Dorsch, contributing editor
Exposures, and reducing their cost, were a theme running through the 2015 SPIE Advanced Lithography Symposium this week in San Jose, Calif., the center of Silicon Valley.
Doubts about the continued viability of Moore’s Law abound as the 50th anniversary of Gordon Moore’s historic article for Electronics magazine draws near. Lithographers are under immense industry pressure to lower the operating costs of lithography cells in the fab while increasing wafer throughput.
“Enabling,” “productivity,” and “stability” were watchwords frequently repeated throughout the conference. The various merits (and occasional demerits) of electron-beam, extreme-ultraviolet, 193i immersion and nanoimprint lithography technologies were debated and touted over four days.
One of the technical sessions closing out Wednesday at the San Jose Convention Center was devoted to papers on “Multibeam Lithography,” especially e-beam direct-write technology, which has been seen as “pie in the sky” for many years, yet seems closer to realization than before.
Hans Loeschner of IMS Nanofabrication described how his company’s e-beam tool has progressed from alpha to beta status this year, and predicted it would be ready for production applications in 2016. Altera, CEA-Leti, and MAPPER Lithography presented a total of three papers on MAPPER’s FLX-1200 e-beam direct-write system, saying it is better able to make chips with 20-nanometer features than an immersion lithography system.
The eBeam Initiative held its annual luncheon at SPIE Advanced Lithography on Tuesday, emphasizing how multibeam mask writing, model-based mask data preparation, and complex inverse lithography technology can enable continued density scaling at the 10-nanometer process node.
“We have reached a point with traditional rules-based designs where the rules are so conservative and the implementation costs are so high that the semiconductor industry has started to lose the economic benefits of scaling to smaller design nodes for system-on-chip designs,” D2S CEO Aki Fujimura said in a statement. “A simulation-based approach combining complex ILT, MB-MDP and existing variable shaped beam mask writers in parallel with the impending emergence of multibeam mask writing are providing platforms to enable the semiconductor industry to reverse this trend and reactivate the density benefits associated with Moore’s Law.”
EUV, another technology that has had a long gestation, was the subject of a conference track over all four days, with photomask and photoresist issues being discussed in several sessions.
The news that Taiwan Semiconductor Manufacturing was able to process 1,022 wafers in 24 hours with ASML Holding’s NXE:3300B scanner was the talk of the SPIE conference on Tuesday, the first day of the two-day exhibition, which had about 60 companies occupying booths. ASML didn’t declare an end to development of its EUV systems, saying there is more work to be done. This includes development of a pellicle for the scanner’s reticles and working with resist suppliers on formulas for EUV resists.
While improvements in all types of lithographies were discussed at the conference, there was increased interest in directed self-assembly, which employs polymers to get molecules to arrange themselves in lines and spaces with a patterning guide. Advances in reducing the defectivity of DSA were reported by imec, Merck, and Tokyo Electron.
Global interest in DSA over the past four years has accelerated due to “other things getting delayed,” said Tom Ferry of Synopsys. Among other initiatives, the electronic design automation software and services company was talking about how its S-Litho molecular simulator, S-Litho shape optimizer, and Proteus ILT guide patterning tool can help enable DSA research and development, design, and manufacturing.
The Belgium-based imec was a big contributor to conference presentations, with a first author on 18 papers and posters, and a co-author of 25 publications.
While EUV garnered headlines during SPIE Advanced Lithography, the Cymer subsidiary of ASML was at the conference to talk about its third-generation XLR 700ix light source for deep-ultraviolet lithography systems. Ted Cacouris of Cymer said, “10 nanometer is basically done with DUV. It could go to 7 nanometer; immersion could be extended. It could be complementary to EUV.”
Cymer also announced its DynaPulse program, an upgrade for its OnPulse subscription service for maintenance and repair of light sources. In 2012, prior to the company’s acquisition by ASML, Cymer derived nearly 70 percent of its light-source revenue from the OnPulse service program.
It’s been an interesting week, with about 2,400 attendees from around the world gathering for the premier lithography conference of the year. They will convene again a year from now to learn what’s new in lithography.