Liu Xiangyue, Zhang Zhe, Song Hongxuan, Huang Qiushi, Huo Tonglin, Zhou Hongjun, Qi Runze, Zhang Zhong, Wang Zhanshan
Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.
MOE Key Laboratory of Advanced Micro-Structured Materials, No. 1239 Siping Road, Shanghai 200092, China.
Micromachines (Basel). 2023 Feb 24;14(3):526. doi: 10.3390/mi14030526.
The Mo/Si multilayer mirror has been widely used in EUV astronomy, lithography, microscopy and other fields because of its high reflectivity at the wavelength around 13.5 nm. During the fabrication of Mo/Si multilayers on large, curved mirrors, shadow mask was a common method to precisely control the period thickness distribution. To investigate the effect of shadow mask on the microstructure of Mo/Si multilayers, we deposited a set of Mo/Si multilayers with and without the shadow mask on a curved substrate with aperture of 200 mm by direct current (DC) magnetron sputtering in this work. Grazing incidence X-ray reflectivity (GIXR), diffuse scattering, atomic force microscope (AFM) and X-ray diffraction (XRD) were used to characterize the multilayer structure and the EUV reflectivity were measured at the National Synchrotron Radiation Laboratory (NSRL) in China. By comparing the results, we found that the layer microstructure including interface width, surface roughness, layer crystallization and the reflectivity were barely affected by the mask and a high accuracy of the layer thickness gradient can be achieved.
由于Mo/Si多层膜镜在13.5nm左右波长处具有高反射率，已被广泛应用于极紫外天文学、光刻、显微镜等领域。在大型曲面镜上制备Mo/Si多层膜时，荫罩是精确控制周期厚度分布的常用方法。为了研究荫罩对Mo/Si多层膜微观结构的影响，本工作通过直流磁控溅射在孔径为200mm的曲面衬底上沉积了一组有无荫罩的Mo/Si多层膜。采用掠入射X射线反射率（GIXR）、漫散射、原子力显微镜（AFM）和X射线衍射（XRD）对多层膜结构进行表征，并在中国国家同步辐射实验室（NSRL）测量了极紫外反射率。通过比较结果，我们发现包括界面宽度、表面粗糙度、层结晶在内的层微观结构和反射率几乎不受荫罩影响，并且可以实现层厚度梯度的高精度控制。
