Diffusion-induced structural changes in La/B-based multilayers for 6.7-nm radiation

Abstract. The thermal stability of La/B and LaN/B multilayers was investigated. The two multilayer systems were found to have comparable subångström period expansion upon annealing in the temperature range of 250°C to 400°C. For La/B multilayers, wide angle x-ray diffraction analysis revealed that the size of LaB6 crystallites present did not change significantly upon thermal treatment. Using grazing incidence x-ray reflectometry, strong change in the internal structure due to interdiffusion at the interfaces of La/B multilayers was observed after annealing. This, coupled to the unchanged crystallinity, suggested the growth of amorphous lanthanum boride interlayers. At wavelength reflectance, measurements showed that as-deposited LaN/B multilayers had an enhanced optical contrast compared with La/B. During thermal loading, the rate of diffusion-induced reflectance decrease in LaN/B multilayers was slower than in La/B. The enhanced thermal stability of LaN/B was attributed to the slower growth of LaN-B interfaces compared with La-B.

[1]  T. Lundström,et al.  Thermal expansion of -rhombohedral boron , 1998 .

[2]  Structural Re-Organization Kinetics of Nanocrystalline Pt Films during In Situ Annealing , 2012 .

[3]  Multilayer mirror for x rays below 190 eV. , 2001, Optics letters.

[4]  Eric Louis,et al.  Nanometer interface and materials control for multilayer EUV-optical applications , 2011 .

[5]  F. Bijkerk,et al.  In-situ study of the diffusion-reaction mechanism in Mo/Si multilayered films , 2011 .

[6]  Shiyu Sun,et al.  Nitrogen doping and thermal stability in HfSiOxNy studied by photoemission and x-ray absorption spectroscopy , 2005 .

[7]  Franz Schäfers,et al.  High performance La/B4C multilayer mirrors with barrier layers for the next generation lithography , 2013 .

[8]  Eric Louis,et al.  Nitridation and contrast of B4C/La interfaces and X-ray multilayer optics , 2010 .

[9]  Eric Louis,et al.  Spectral properties of La/B--based multilayer mirrors near the boron K absorption edge. , 2012, Optics express.

[10]  Frederik Bijkerk,et al.  Temperature-dependent nanocrystal formation in Mo/Si multilayers , 2007 .

[11]  Eric Louis,et al.  Reflective multilayer optics for 6.7 nm wavelength radiation sources and next generation lithography , 2009 .

[12]  John Arnold,et al.  EUV lithography at the 22nm technology node , 2010, Advanced Lithography.

[13]  B. Sonderegger,et al.  A heating stage up to 1173 K for X-ray diffraction studies in the whole orientation space , 2003 .

[14]  Simone Raoux,et al.  Crystallization dynamics of nitrogen-doped Ge2Sb2Te5 , 2009 .

[15]  N. Ceglio,et al.  Wavelength considerations in soft-x-ray projection lithography. , 1993, Applied optics.

[16]  I. Makhotkin.  Structural and reflective characteristics of multilayers for 6.x nm wavelength , 2013 .

[17]  D. Attwood.  Soft X-Rays and Extreme Ultraviolet Radiation , 1999 .