Hubbard William A, Lodico Jared J, Ling Xin Yi, Zutter Brian T, Yu Young-Sang, Shapiro David A, Regan B C
Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Ultramicroscopy. 2021 Mar;222:113198. doi: 10.1016/j.ultramic.2020.113198. Epub 2020 Dec 30.
Total electron yield (TEY) imaging is an established scanning transmission X-ray microscopy (STXM) technique that gives varying contrast based on a sample's geometry, elemental composition, and electrical conductivity. However, the TEY-STXM signal is determined solely by the electrons that the beam ejects from the sample. A related technique, X-ray beam-induced current (XBIC) imaging, is sensitive to electrons and holes independently, but requires electric fields in the sample. Here we report that multi-electrode devices can be wired to produce differential electron yield (DEY) contrast, which is also independently sensitive to electrons and holes, but does not require an electric field. Depending on whether the region illuminated by the focused STXM beam is better connected to one electrode or another, the DEY-STXM contrast changes sign. DEY-STXM images thus provide a vivid map of a device's connectivity landscape, which can be key to understanding device function and failure. To demonstrate an application in the area of failure analysis, we image a 100 nm, lithographically-defined aluminum nanowire that has failed after being stressed with a large current density.
总电子产额（TEY）成像技术是一种成熟的扫描透射X射线显微镜（STXM）技术，它基于样品的几何形状、元素组成和电导率产生不同的对比度。然而，TEY-STXM信号仅由束流从样品中射出的电子决定。一种相关技术，即X射线束诱导电流（XBIC）成像，对电子和空穴分别敏感，但需要样品中有电场。在此，我们报告多电极器件可以进行布线以产生差分电子产额（DEY）对比度，它同样对电子和空穴分别敏感，但不需要电场。根据聚焦的STXM束照射的区域与一个电极还是另一个电极连接得更好，DEY-STXM对比度会改变符号。因此，DEY-STXM图像提供了器件连接情况的直观图谱，这对于理解器件功能和失效可能至关重要。为了展示在失效分析领域的应用，我们对一根经过光刻定义的100纳米铝纳米线进行成像，该纳米线在承受大电流密度应力后失效。
