Development of soft-X-ray multilayer polarizing elements amd their application to soft-X-ray ellipsometry

该项目的目标是1。通过将软X射线多层膜偏振元件的性能提高到实用水平，建立了软X射线偏振测量与控制的方法。与此同时，2。优化多层的材料对及其周期厚度以增加可用的波长区域。然后，与高性能偏振器，3。软X射线椭偏测量将发展成为一种新的精密表面分析方法。本研究为期两年，主要内容如下：1.在波长为13nm的波长下，我们研制了λ/4和λ/2的自支撑MO/Si多层膜。偏振性能通过旋转分析器椭圆偏振法与使用反射多层偏振器在光子工厂，KEK。多层膜是针对水窗区域的波长开发的，其中反射率仍然保持在几个%的水平。根据光学标准，将Sc与Cr、Ni、Si、C和Al配对，制备了100对多层膜，发现Sc/Cr配对的多层膜具有最好的周期性。进一步的制造具有改进的溅射速率的稳定性和优化的衬底温度在70 ℃左右，Sc/Cr为250对，在3.1nm的波长处显示出15%的最高反射率。用消光比为0.001的偏振片对40nm厚的Mo膜样品进行了软X射线椭圆偏振测量。这揭示了在入射角响应中的共振状结构，其中通过用具有粗糙边界的单层模型进行分析，预期厚度为0.01nm、折射率为0.001、消光比为0.0001的极高灵敏度。

This project aims 1. establishments of polarization measurements and control in the soft X-ray by improving performances of soft X-ray multilayer polarizing elements to a practical level. In parallel to this, 2. material pairs of the multilayers and their period thicknesses are optimized to increase a wavelength region available. Then, with the high performance polarisers, 3. soft X-ray. ellipsometry will be developed as a new precision method of surface analysis. The two-year research is summarized in the following.1. Free standing MO/Si multilayers were developed as lambda/4 and lambda/2 plates at a wavelength of l3nm. The polarization performance was evaluated by rotating analyser ellipsometry with use of reflection multilayer polarizer at the photon factory, KEK.2. Multilayers were developed for the wavelengths of the water window region where the reflectances still remain at a level of a few %. Based on a optical criteria, Sc was paired with Cr, Ni, Si, C, and Al to fabricate multilayers of 100pairs, which revealed Sc/Cr as a pair showing the best periodicity. Further fabrication with improved stability of the sputtering rate and with optimized substrate temperature of around 70oC, Sc/Cr of 250 pairs showed the highest reflectance of 15% at a wavelength of 3.1nm.3. With polarisers of 0.001 extinction ratio, a sample of 40nm thick Mo layer was studied by soft X-ray ellipsometry. This revealed resonance like structures in the angle of incidence response where extremely high sensitivities of 0.0 1nm for the thickness, 0.001 for the refractive index, and 0.0001 for the extinction ratio were expected by analysis with a single layer model with rough boundaries.