Eriksson Fredrik, Johansson Göran A, Hertz Hans M, Gullikson Eric M, Kreissig Ulrich, Birch Jens
Thin Film Physics Division, Department of Physics, Linköping University, 58183 Linköping, Sweden.
Opt Lett. 2003 Dec 15;28(24):2494-6. doi: 10.1364/ol.28.002494.
Cr/Sc multilayer mirrors, synthesized by ion-assisted magnetron sputter deposition, are proved to have a high near-normal reflectivity of R = 14.5% at a grazing angle of 87.5 degrees measured at the wavelength lambda = 3.11 nm, which is an improvement of more than 31% compared with previously published results. Elastic recoil detection analyses show that the mirrors contained as much as 15 at. % of N and traces of C and O. Soft x-ray reflectivity simulations reveal interface widths of sigma = 0.34 nm and an exceptionally small layer thickness drift of approximately 1.6 x 10(-5) nm/multilayer period throughout the stack. Simulations show that a reflectivity of R = 25.6% is attainable if impurities and layer thickness drift can be eliminated. The abrupt interfaces are achieved with ion assistance with a low ion energy of 24 eV and high ion-to-metal flux ratios of 7.1 and 23.1 during Cr and Sc sputter deposition, respectively. In addition, a near-normal incidence reflectivity of 5.5% for the C VI emission line (lambda = 3.374 nm) from a laser plasma source was verified.
通过离子辅助磁控溅射沉积合成的Cr/Sc多层镜，在波长λ = 3.11 nm下测量，当掠射角为87.5度时，其近垂直反射率高达R = 14.5%，与先前发表的结果相比提高了31%以上。弹性反冲检测分析表明，该多层镜含有高达15原子%的N以及痕量的C和O。软X射线反射率模拟显示，界面宽度σ = 0.34 nm，并且在整个堆叠结构中，每层的厚度漂移异常小，约为1.6×10⁻⁵ nm/多层周期。模拟表明，如果能够消除杂质和层厚漂移，反射率可达到R = 25.6%。在Cr和Sc溅射沉积过程中，通过离子辅助实现了陡峭的界面，其中Cr溅射沉积时离子能量低至24 eV，离子与金属通量比为7.1；Sc溅射沉积时离子与金属通量比为23.1。此外，还验证了来自激光等离子体源的C VI发射线（λ = 3.374 nm）的近垂直入射反射率为5.5%。
