【作者】 王蓓；

【导师】 王占山； 朱京涛；

【作者基本信息】 同济大学 ， 光学工程， 2007， 硕士

【摘要】 多层膜技术极大地提高了光学元件对极紫外光和软X射线的反射率，有力地促进了该波段光学系统的发展，已在天文学、显微成像、光刻、同步辐射应用以及X射线激光等领域得到了广泛的应用。工作波长为4.48nm的高反射镜是类镍钽软X射线激光实验及其应用的核心元件，因此，进行4.48nm多层膜高反射镜的设计、制备与检测研究具有重要意义。 类镍钽软X射线激光用反射镜是周期多层膜，其膜层厚度小、周期数多，制备难度大，实际反射率远小于设计值。目前，只有美国、德国、日本等研制了实用的元件，但我国对此类高反射镜还未进行深入研究。 本文探讨了类镍钽软X射线激光用多层膜反射率的计算方法。针对材料的光学特性、物理化学性质和成膜特点，选择了Cr/C、Co/C和Cr/Sc多层膜材料对。计算了不同结构参数下，多层膜的峰值(工作波长4.48nm，入射角5°)反射率，比较了几种材料对的反射性能。利用Stearns散射理论，模拟了多层膜界面缺陷对反射性能的影响。 采用超高真空磁控溅射镀膜设备制备了不同结构参数的Cr/C、Co/C和Cr/Sc多层膜样品。用X射线小角反射方法测量了多层膜周期，对镀膜材料的溅射速率进行了精确标定。通过反复实验研究，优化了充气方式、基片偏压、溅射功率等工艺条件，分析了制备工艺对成膜质量的影响，找到了比较好的镀膜工艺参数。实验上比较了不同结构多层膜的性能，得到了便于制作的多层膜结构参数。 使用高分辨率X射线衍射仪测量了多层膜的小角反射曲线和散射曲线，结果表明样品的膜层结构好、厚度误差小。对测量曲线进行了数值拟合，得到了拟合结果，分析了影响Cr/C、Co/C和Cr/Sc多层膜反射率下降的主要原因。在德国BESSY Ⅱ同步辐射装置上测量了多层膜的反射率，其中，Cr/C和Cr/Sc多层膜的峰值反射率分别达到7.50％和6.27％，表明研制的类镍钽软X射线激光用高反射镜已基本满足了实际应用要求。更多还原

【Abstract】 Multilayer mirrors, which permit the achievement of high normal incidence reflectivity in soft x-ray and EUV region, are the enabling technology for the significant improvements of optical imaging systems. These mirrors are now finding wide application in instrumentation for astronomy, microholography of biological samples, EUV lithography, synchrotron radiation, X-ray laser and so on. The high reflective mirrors for Ni-like Ta soft X-ray laser, working at 4.48nm, are the core elements in Ni-like Ta laser experiment and its application experiment. So the research on design, fabrication and measurement of 4.48nm high reflective mirrors is very important and meaningful.The high reflective mirrors for Ni-like Ta soft X-ray laser are periodical multilayers, whose layer thickness is small and the period number is large, which make them extremely difficult to fabricate. And the experimental reflectivity of prepared mirrors is much lower than the academic. Now, only the high reflective mirrors for Ni-like Ta soft X-ray laser made in a small number of countries like America, Germany and Japan meet the practical requirements. However, China hasn’t do deep research on this kind of high reflective mirrors.In the thesis, the calculating method of reflectivity is discussed. According to the optical properties, the physical, chemical properties, and the film forming characteristics, Cr/C, Co/C and Cr/Sc are chosen as the material pairs. The reflective characteristics of multilayers made of different materials are compared. The multilayer structure parameters and peak reflectivity are yielded after the theoretical analysis. The effects of multilayer interface defects are dicussed based on D. Stearns dispersion theory.Cr/C, Co/C and Cr/Sc high reflective mirrors with different structures are fabricated by using DC magnetron sputtering methods. The deposition rates of different materials were accurately calibrated by using low angle X-ray reflectivity measurement. The fabricating parameters such as gas flux, bias voltage and sputtering更多还原