DFG-RSF: Beryllium based multilayer optics for the EUV spectral range

在我们的同步辐射设施BESSY-II上，最近一个新的波长计量站已经投入使用，可以测量软x射线辐射的光学元件的设计波长。该站结合了我们在软x射线光学和技术方面20年的专业知识，在测量能力方面具有尖端的性能。对于光学性能与波长密切相关的多层光学元件，波长表征技术是必不可少的。此类信息无法通过任何其他方法获得。我们希望利用这一设施来开发一种新型的多层光学器件，在极紫外光及其他辐射范围内具有良好的性能。在这个项目中，我们希望与下诺夫哥罗德微观结构物理研究所（IPM-RAS）的世界上最大的多层设施之一合作，我们已经与该研究所成功合作了二十多年。该研究所将应用各种溅射和离子束辅助原子工程技术生产含铍多层材料（Al/Be, Ru/Be, Mo/Be, Mg/Be，…），以提供光滑的层和尖锐的界面，可以忽略相互扩散。AFM、Cu k- α衍射等实验室技术将用于标准性能测试，而它们的最终性能将通过波长计量、共振反射率和反射- nexafs在构成原子的吸收边缘进行同步辐射表征，以进行深度选择的化学和元素分析。这种多层结构有许多应用，其性能将超过现有的（Mo/Si），例如用于下一代EUV纳米光刻或太阳天文学。我们对这种多层光学器件的兴趣是双重的：(1)我们希望开发具有高反射率的新型Be-ML光学器件，用于偏振转向和控制。(2)由于我们能够制造高精度的火焰光栅，我们想在光栅上涂上多层涂层。这样可以大大提高衍射效率。在成功演示be多层性能后，计划将这种新型多层涂层涂在大型光栅上，并在BESSY II上实现光束线。

At our synchrotron radiation facility BESSY-II recently a new At-Wavelength Metrology Station has been set into operation with which optical components for soft x-ray radiation can be measured at their design wavelength. This station incorporates our 20 years of expertise in soft x-ray optics and technology and it has a cutting-edge performance with respect to its measuring capabilities. The At-Wavelength characterization technique is indispensable in particular for multilayer optical elements of which the optical performance is strongly wavelength-dependent. Such information cannot be obtained by any other method. We want to use this facility to develop a novel kind of multilayer optics with promising performance in the range of EUV radiation and beyond. In this project we want to cooperate with one of the world's largest multilayer facility at the Institute for Physics of Microstructure in Nizhny Novgorod (IPM-RAS) with which we have cooperated successfully since more than two decades. This institute will produce Beryllium-containing multilayers (Al/Be, Ru/Be, Mo/Be, Mg/Be,...) applying various sputter- and ion-beam assisted techniques of atomic engineering to provide smooth layers and sharp interfaces with negligible interdiffusion. Laboratory techniques such as AFM, Cu k-alpha diffractometry etc. will be applied for standard performance tests, while their final performance is characterized with synchrotron radiation by At-Wavelength Metrology, Resonant Reflectivity and Reflection-NEXAFS at the absorption edges of the constituting atoms for depth-selected chemical and elemental analysis. There are many applications of such multilayer structures, which will exceed the performance of existing ones (Mo/Si), for instance for the next generation of EUV nanolithography or for solar astronomy. Our interest in such a multilayer optics is twofold: (1) We want to develop new Be-ML optics with high reflectivity for polarization steering and control. (2) Since we are able to manufacture high-precision blazed gratings, we want to apply a multilayer coating on top of a grating. The diffraction efficiency then can be increased considerably. After successful demonstration of the Be-multilayer performance a large grating is planned to be coated with such a novel multilayer and implemented into a beamline at BESSY II.