Collection of secondary electrons in scanning electron microscopes
Collection of secondary electrons in scanning electron microscopes
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DOI：
10.1111/j.1365-2818.2009.03189.x
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发表时间：
2009-12-01
影响因子：
2
通讯作者：
Konvalina, I.
中科院分区：
文献类型：
--
作者：
Mullerova, I.;Konvalina, I.
对扫描电子显微镜中二次电子的收集进行了模拟，并对两种物镜透镜和三种探测系统的结果进行了实验验证。给出了两种物镜的像差系数和样品区的最大轴向磁场。比较是一个标准的侧附加的二次电子探测器，其中只有弱静电和几乎没有磁场的影响，在试样附近的信号轨迹，和侧附加（下）和上探测器在一个浸没系统与弱静电，但强磁场穿透向试样。计算所有三种检测系统和几种工作距离的收集效率。计算了不同初始方位角和极角下探测器对二次电子轨道的吸引能力。根据预期，浸没系统的下部检测器不收集从样品发射的二次电子I和II，并且仅背散射电子和二次电子III形成最终图像。浸没系统的上部探测器呈现出几乎100%的收集效率，然而，随着工作距离的增加，但令人遗憾的是，其图像中的形貌对比度被抑制。标准探测器的收集效率在短工作距离下较低，但在相同距离下会增加，从而保持较强的地形对比度。
P>Collection of the secondary electrons in the scanning electron microscope was simulated and the results have been experimentally verified for two types of the objective lens and three detection systems. The aberration coefficients of both objective lenses as well as maximum axial magnetic fields in the specimen region are presented. Compared are a standard side-attached secondary electron detector, in which only weak electrostatic and nearly no magnetic field influence the signal trajectories in the specimen vicinity, and the side-attached (lower) and upper detectors in an immersion system with weak electrostatic but strong magnetic field penetrating towards the specimen. The collection efficiency was calculated for all three detection systems and several working distances. The ability of detectors to attract secondary electron trajectories for various initial azimuthal and polar angles was calculated, too. According to expectations, the lower detector of an immersion system collects no secondary electrons I and II emitted from the specimen and only backscattered electrons and secondary electrons III form the final image. The upper detector of the immersion system exhibits nearly 100% collection efficiency decreasing, however, with the working distance, but the topographical contrast is regrettably suppressed in its image. The collection efficiency of the standard detector is low for short working distances but increases with the same, preserving strong topographical contrast.