December 13, 2005, Oberkochen, Germany--Carl Zeiss SMT has shipped the first optical system for an extreme ultraviolet (EUV) lithography tool to ASML (Veldhoven, The Netherlands), a provider of lithography systems for the semiconductor industry. A next-generation technology, EUV is based on a 13-nm illumination wavelength, which allows chipmakers to print feature sizes of 32 nm and below on integrated circuits.
The EUV projection optics from Carl Zeiss will be incorporated in the EUV Alpha demo tools. Unlike all lithography systems used in production today, the EUV projection optics fully consist of mirrors as there are no optical materials which are transparent for EUV, as the light would be absorbed. Requirements on these highly sophisticated EUV mirrors are exceptional.
The aspherically curved surfaces of the reflective elements are produced with a contouring accuracy of only a few atoms; surface roughness may also not exceed a few atoms in order to precisely image the mask structures onto the wafer without blurs. The whole projection system, comprising six mirrors, positioned and adjusted with extreme accuracy, works in high vacuum since even minute amounts of residual gas would absorb the EUV radiation. The coatings of the mirror-substrates also play a decisive role. Sufficient reflectivity can only be reached with a stack of more than 50 double layers consisting of alternating layers of molybdenum and silicon (Mo/Si); each of these double layers has a thickness of less than 10 nm.
Dr. Andreas Dorsel, senior VP and general manager of Carl Zeiss SMT´s Lithography Optics Divison explains: "EUVL ist most likely going to play a vital role in structuring future micro-chips. We are happy, to now reap the first results of our long lasting R&D efforts in this field. Delivery of the first optical system for ASML´s EUVL alpha demo tool is an important milestone in the introduction of EUVL for mass production of IC´s."