Depth-graded multilayers for application in transmission geometry as linear zone plates
Depth-graded multilayers for application in transmission geometry as linear zone plates
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DOI：
10.1063/1.2138378
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发表时间：
2005-12-01
影响因子：
3.2
通讯作者：
Stephenson, GB
中科院分区：
文献类型：
--
作者：
Liu, C;Conley, R;Stephenson, GB
用于X射线聚焦光学的菲涅尔波带片通常是使用光刻技术制造的。为了实现硬X射线的最佳效率，需要几微米的深度，这限制了最小区域宽度，从而限制了使用光刻可以实现的最小焦点尺寸。我们正在探索通过另一种技术来制造波带片，以克服这些限制：用于透射式(Laue)衍射几何的多层膜的生长，其中连续层的厚度根据菲涅尔区公式逐渐增加；在生长到所需深度后，对膜进行切片。对于平面多层膜，这产生了可以在一维上聚焦X射线的线性波带片。在这里，我们报告了适合用作硬X射线聚焦波带片的深度梯度多层膜的生长和表征。该多层膜共有470层WSi2和Si交替层，厚度从15 nm单调增加到60 nm，总厚度为11.33微米，其中一大挑战是理解和选择适合这种厚多层膜的材料体系。我们发现WSi2/Si是一个很有前途的体系。对WSi2/Si多层膜和W/Si多层膜进行了比较。(C)2005年美国物理研究所。
Fresnel zone plates for x-ray focusing optics are typically made using lithographic techniques. To achieve optimum efficiency for hard x rays, a depth of several microns is required, which limits the minimum zone width and hence minimum focal spot size achievable using lithography. We are exploring the fabrication of zone plates by an alternative technique that surmounts these limitations: the growth of a multilayer film to be used in transmission (Laue) diffraction geometry, in which the thickness of consecutive layers gradually increases according to the Fresnel zone formula; the film is sectioned after growth to the required depth. For a planar multilayer, this produces a linear zone plate that can focus x rays in one dimension. Here we report the growth and characterization of a depth-graded multilayer suitable for use as a zone plate for hard x-ray focusing. The multilayer has a total of 470 alternating layers of WSi2 and Si with thicknesses increasing monotonically from 15 to 60 nm, for a total thickness of 11.33 mu m. One of the major challenges is to understand and select the right material system for this kind of thick multilayer. We have found that WSi2/Si is a promising system. A comparison between WSi2/Si and W/Si multilayers is presented. (c) 2005 American Institute of Physics.