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EUVL Overview

The continued development of extreme ultraviolet (EUV) lithography technology is a result of a partnership between LLNL, Lawrence Berkeley National Laboratory, Sandia National Laboratory, and an industry consortium composed of AMD, Intel, and Motorola. The team's strategy has been to focus on specific technologies for EUV lithography, including

  • EUV Optics and System -- The application of 11- to 13-nm EUV light to lithography tools that print critical dimensions (Cds) in the 30- to 100-nm range requires high-precision reflective optics.

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These optics are used in the condenser to collect the EUV radiation from the source and to focus the radiation onto the reflective reticle in the camera to reproduce an image of the mask pattern onto the wafer. Each of the mirrors must be manufactured and assembled in the lithography subsystem to maximize the imaging efficiency and reduce distortion.

  • EUVL Masks -- EUVL uses a reflective mask, and reflectivity at EUV wavelengths is obtained by coating a mask substrate with multilayers. The challenges include detection of sparse sub-micron defects on large fields.
  • EUVL Thin Films/Coatings -- The multilayer coatings for EUV lithography systems typically consist of alternating layers of molybdenum and silicon (MO/Si) or molybdenum and beryllium (Mo/Be). The primary materials-dependent characteristics of EUV multilayer mirrors are reflectance, stress, and stability. Using an athermal buffer-layer technique with amorphous silicon and Mo/Be buffer-layers, it has been possible to obtain Mo/Be and Mo/Si multilayers with a near-zero net film stress and less than a 1% loss in reflectance. Disposition technology challenges include thickness control and repeatability.
  • Metrology at near-atomic dimensions -- High-accuracy metrology tools are prerequisites for fabricating the precision optics for EUVL. Improvements in figure metrology have been made that will enable the absolute measurement of surfaces to the accuracy required.

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UCRL-MI-142843