EUV metrology of multilayer optics

  title={EUV metrology of multilayer optics},
  author={Avijit K. Ray-Chaudhuri and Richard H. Stulen and Wai-Yin Ng and Francesco Cerrina and S. Spector and Zhiqiang Tan and John Ernst Bjorkholm and D. Tennant},
EUV metrology is central to the successful commercialization of EUV projection lithography. Metrology carried out at the EUV wavelength of 13 nm enables a gain of {approximately}50 in precision when translated from visible light wavelengths. It also uniquely measures wavefront errors due to lateral variations in the inherent phase shift upon reflection from the multilayer coating. The authors present the development of two metrology techniques: EUV Foucault and Ronchi tests.