A new band-pass energy filter (BPF) technique of secondary electron (SE) detection using scanning electron microscope (SEM) was developed to enhance voltage contrast (VC) in SEM images. The energy filtering condition was optimized to enhance VC of dopant distribution using Si p-n structure. The relation between VC and SE energy was investigated by BPF as well as a conventional high-pass filter (HPF). Whereas the p-type regions were always brighter than the n-type region in the case of HPF, the contrast reversal between p region and n region occurred at the low SE energy range in the case of BPF. The variation of signal intensity of BPF against specimen bias voltage can be considered as SE spectrum analysis, and the peak split of the spectra between n-type and p-type regions was obtained. The peak split can be explained with a model with metal-semiconductor contact. This peak split causes the contrast reversal.

中文翻译：

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场发射扫描电子显微镜中能量过滤信号的电压对比成像

开发了一种使用扫描电子显微镜 (SEM) 进行二次电子 (SE) 检测的新带通能量滤波器 (BPF) 技术，以增强 SEM 图像中的电压对比度 (VC)。优化能量过滤条件以使用 Si pn 结构增强掺杂剂分布的 VC。通过 BPF 以及传统的高通滤波器 (HPF) 研究了 VC 和 SE 能量之间的关系。在 HPF 的情况下，p 型区域总是比 n 型区域更亮，而在 BPF 的情况下，p 区域和 n 区域之间的对比度反转发生在低 SE 能量范围内。BPF 的信号强度随样品偏置电压的变化可以被认为是 SE 光谱分析，并获得了 n 型和 p 型区域之间的光谱峰分裂。峰分裂可以用金属-半导体接触的模型来解释。这种峰值分裂导致对比度反转。