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Support for EUV Lithography: Metrology with 13 nm Radiation

The steady drive towards miniaturization in the semiconductor engineering industry calls for photolithographic processing with ever decreasing radiation wavelengths. This constitutes a new challenge for metrology, too. At present, extreme ultraviolet (EUV) lithography, a "next generation" technology, is starting to be realized. In support of this development, PTB is making extensive use of synchrotron radiation at wavelengths around 13 nm.

Reflectometer used by PTB for the characterisation of optical components (mirrors, gratings, filters) with monochromatized synchrotron radiation

The structure width of memory chips for computers is one standard example of the progress semiconductor technology is making. During the last three decades, the width has been reduced by a factor of 2 every five years. According to the annual "International Technology Roadmap for Semiconductors", the guideline for development work, this trend is to be continued for at least another fifteen years until structure widths are down to about 20 nm.

Photolithography with EUV radiation and electron-beam projection lithography are considered as the most promising techniques to produce semiconductor structure widths of 70Ênm and less in the future. Photolithography technology requires "at wavelength" metrology with 13 nm radiation on a large scale. In order to meet this demand PTB is making extensive use of several measuring facilities in its synchrotron radiation laboratory at the Berlin electron storage ring BESSY II. At present, the main tasks are:

  • to determine the reflectivity and homogeneity of Mo/Si multilayer mirrors to be used for projection of mask structures onto wafers with typical relative uncertainties of 0,2 %
  • to investigate the degradation of EUV optical elements, filters and detectors subjected to intense EUV irradiation
  • to develop methods for the characterization of optical EUV projection systems
  • to calibrate measuring instruments such as spectrographs and filter-photodiode systems to be used for the characterization of EUV radiation sources with uncertainties down to 1 %.

Work in this field is carried out in close collaboration with industry and research institutes in the frame of national and international funding programmes.

Contact at PTB:

Phone: +49-531-592-0