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

在我们的同步辐射设施BESSY-II，一个新的波长计量站已经投入运行，利用它可以在设计波长下测量用于软X射线辐射的光学元件。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性能。尤其是对于光学性能强烈依赖于波长的多层光学元件而言，波长下的表征技术是必不可少的。这种信息不能通过任何其他方法获得。我们希望利用这一设备开发一种新型的多层光学器件，在EUV辐射范围内和更远的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结构物理研究所(IPM-RAS)世界上最大的多层设施之一合作，自20多年来，我们一直与该机构成功合作。该研究所将生产含铍多层膜(Al/Be、Ru/Be、Mo/Be、Mg/Be等)。应用各种溅射和离子束辅助的原子工程技术，以提供光滑的层和尖锐的界面，而相互扩散可以忽略不计。实验室技术，如原子力显微镜、铜k-α衍射仪等将用于标准性能测试，而它们的最终性能将通过波长计量学、共振反射率和组成原子吸收边的反射NEXAFS来表征，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多层结构(Mo/Si)，例如用于下一代EUV纳米光刻或太阳天文学。我们对这种多层膜光学的兴趣有两个方面：(1)我们想要开发新的具有高反射率的BE-ML光学器件，用于偏振控制和控制。(2)由于我们能够制造出高精度的闪耀光栅，我们希望在光栅上涂上一层多层膜。这样可以大大提高衍射效率。在成功地展示了Be-多层膜的性能之后，计划在BESSY II上用这种新型多层膜覆盖一个大的光栅，并将其应用到光束线中。

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.