Energy Filtered Detector for Micro-Diffraction in the Scanning Electron Miscroscope

基于微衍射的晶体学对于微电子、超导、太阳能、结构复合材料和金属成形等关键工业应用中的材料设计和工艺理解至关重要。扫描电子显微镜（SEM）具有提供高空间分辨率晶体学信息的潜力，但现有技术的低灵敏度严重限制了其适用性。目前的方法不能很容易地用于剂量敏感材料、电非导体和即使只有少量表面损伤的样品。获得显微衍射数据的困难是扫描电镜的一个主要缺点，否则它对于获得高分辨率的地形和成分信息非常有用，通常只需要很少的样品制备。这个第一阶段的计划将确定采用高增益的能量滤波检测器来提高扫描电镜微衍射灵敏度的可行性。该滤波器将应用于能提供高空间分辨率晶体学信息的背散射电子模式。这项研究将需要一种对低能电子敏感的放大元件，如微通道板。本研究将测试该方法的整体可行性，以及动态范围和噪声水平的具体问题。利用拟议的研究将提高国内工业的竞争地位，提高它们识别成分和确定与先进材料和工艺有关的综合特性的能力。此外，它还将扩展现有用于学术和工业研究的大型扫描显微镜的功能。

Micro-diffraction based crystallography is essential to materials design and process understanding in key industrial applications, such as micro-electronics, superconductivity, solar energy, structural composites and metal forming. The scanning electron microscope (SEM) has the potential for providing high spatial resolution crystallographic information, but its applicability is severely limited by the low sensitivity of existing techniques. The current methodology cannot be easily used for dose sensitive materials, electrical nonconductors and samples with even small amounts of surface damage. The difficulty of obtaining micro- diffraction data is a major drawback in the SEM, which otherwise is very useful in obtaining high resolution topographical and compositional information and usually requires minimal specimen preparation. This Phase I program will determine the feasibility of employing an energy filtering detector with high gain to increase the sensitivity of micro-diffraction in the SEM. The filter will be applied to backscattered electron patterns that can provide crystallographic information at very high spatial resolution. This study will require an amplifying element that is sensitive to low energy electrons, such as a microchannel plate. The research will test the overall feasibility of this approach as well as the specific issues of dynamic range and noise level. Exploitation of the proposed research would improve the competitive position of domestic industries by enhancing their capability to identify components and define aggregate properties related to advanced materials and processes. In addition it would extend the functionality of a large existing base of scanning microscopes used in academic and industrial research.