EUV soft X-ray characterization of a FEL multilayer optics damaged by multiple shot laser beam
EUV soft X-ray characterization of a FEL multilayer optics damaged by multiple shot laser beam
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DOI：
10.1016/j.nima.2010.10.026
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发表时间：
2011-04
影响因子：
1.4
通讯作者：
A. Giglia;N. Mahne;A. Bianco;C. Svetina;S. Nannarone
中科院分区：
文献类型：
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作者：
A. Giglia;N. Mahne;A. Bianco;C. Svetina;S. Nannarone
我们研究了 400nm 波长的飞秒脉冲激光束对 Mo/Si EUV 多层膜的破坏作用。曝光是在真空中使用 120fs 的多个脉冲（5 个脉冲/mm2）进行的，激光能量通量在 38-195mJ/cm2 范围内变化。通过不同的技术对不同照射区域进行了异位分析，包括镜面反射率和漫反射率、X射线光电子能谱 (XPS) 以及 EUV 和软 X 射线范围内的总电子产率 (TEY)。表面图像已通过原子力显微镜（AFM）和扫描电子显微镜（SEM）获得。结果清楚地表明，随着激光能量密度的增加，EUV 多层性能逐渐下降。光谱分析可以将反射率的降低与多层堆叠的退化联系起来，这归因于靠近镜子表面的第一层 Mo/Si 界面处的 Mo-Si 混合。
We have investigated the damaging effects of a femtosecond pulsed laser beam with 400nm wavelength on a Mo/Si EUV multilayer. The exposures have been done in vacuum with multiple pulses (5pulses/mm2) of 120fs varying the laser fluence in the 38–195mJ/cm2range. The analysis of the different irradiated regions has been performed ex-situ by means of different techniques, including specular and diffuse reflectivity, X-ray photoemission spectroscopy (XPS) and total electron yield (TEY) in the EUV and soft X-ray range. Surface images have been acquired by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results clearly indicate a progressive degradation of the EUV multilayer performances with the increase of the laser fluence. Spectroscopic analysis allowed to correlate the decrease of reflectivity with the degradation of the multilayer stacking, ascribed to Mo–Si intermixing at the Mo/Si interfaces of the first layers, close to the surface of the mirror.