Interface-engineered EUV multilayer mirrors

• DOI: 10.1016/j.mee.2006.01.126
• Publication Date: 2006-02-20T10:24:56Z
• Authors: Sergiy Yulin; Nicolas Benoit; Torsten Feigl; Norbert Kaiser
• Keywords: 0103 physical sciences; 01 natural sciences

Most applications of Mo/Si multilayer optics in EUV lithographic systems require a high normal-incidence reflectivity. Using dc-magnetron sputtering we achieved R=68.8% at the wavelength of 13.5nm. Different interface-engineered Mo/X/Si/X multilayers with a maximum reflectivity of 69.6% were developed. These new multilayer mirrors consist of molybdenum and silicon layers separated by different interdiffusion barriers (X=C and SiC). The Mo/C/Si/C interface-engineered mirrors were optimized in terms of high peak reflectivity at a wavelength near 13.5nm (R"p>=60.0%) and broad operating temperature range (T=20-500^oC). The best results were obtained with 0.8nm thicknesses of carbon interlayers on both interfaces. The combination of good optical properties and high thermal stability of interface-engineered Mo/C/Si/C multilayer mirrors underlines their potential for their use in EUV optics.