EU partners clarify EUV optics improvements

November 1, 2012 – A group of partners in Europe say they have completed a project to deliver the first EUV lithography optics targeting the 22nm node.

Project participants were led by ASML and included and eight other participants (two Carl Zeiss businesses, six German companies and research facilities) develop EUV lithography. The national project, part of the European "EXEPT" project (EXtreme-UV lithography Entry Point Technology development) and the CATRENE Cluster, was supported with ~€16M from the German Federal Ministry for Education and Research (BMBF).

In a statement, Carl Zeiss summarized and credited the group’s achievements:

  • A more powerful projection lens, highly flexible illumination system without loss of energy, and a high-accuracy measuring systems necessary for their qualification (Carl Zeiss SMT, Oberkochen);
  • New optical elements for the precision measurement of the EUV mirror (IMS, Stuttgart);
  • Mask repair processes for EUV photomasks (Carl Zeiss SMS GmbH, Jena/Rossdorf);
  • Theoretical experiments using special EUV simulation software (Fraunhofer Institute for Integrated Systems and Device Technology, Erlangen);
  • EUV/XUV-based metrology solutions which can be used in reflectometers for the optical characterization of EUV masks (Bruker ASC, Cologne);
  • Process facilities and processes for the cleaning and automated handling of the EUV masks (Süss MicroTec Photomask Equipment, Sternenfels);
  • Facilities for the cleaning and decontamination of the EUV mask transport containers (Dynamic Microsystems, Radolfzell);
  • Appropriate cleaning technologies for 20 nanometer technology EUV masks (Advanced Mask Technology Center, Dresden).

Alignment of EUV optics. (Source: Carl Zeiss)

"The successful collaboration for the further development of this crucial technology helped further strengthen the leading role of German companies in the area of microelectronics," stated Dr. Hermann Gerlinger, Member of the Executive Board of Carl Zeiss AG and CEO of Carl Zeiss SMT GmbH. "Targeted support, like that from BMBF, supports us in expanding the necessary competencies." The demonstrators and technologies developed within the scope of this project (from Süss MicroTec and DMS, alongside Carl Zeiss) have been supplied to customers around the world, they add.

Of course 22nm is hardly the finish line for EUV lithography, or even the starting point — EUV’s potential has been pursued for years now, with technical and cost/benefit hurdles continuing to push out its adoption. BMBF has already committed funding for the next stage of this EUV litho work to improve the projection optics to 14nm resolution. Many in the industry hope EUV lithography will be ready for volume manufacturing by then — and it’s coming up very fast — assuming other improvements can also be achieved in source power and mask infrastructure.

Some improvements in EUV optics were discussed at the International Symposium on Extreme Ultraviolet Lithography in October, including "substantial" improvements to roughness and tolerance specs and a new higher-NA (0.33) mirror design enabling lower resolution. Carl Zeiss and Fraunhofer Institute also reportedly have developed a new collector mirror coating that enables an in-situ hydrogen cleaning process, improving collector mirror lifetime but still far below the lifetime that chip companies would require in a volume production environment.

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