The point spread function (PSF) of the scanning electron microscope (SEM) can be determined using a recently developed nanoparticle calibration method. Many parameters are involved in PSF determination and introduce a previously unstudied amount of uncertainty into the PSF size and shape. Signal type, support material thickness, reference particle size, PSF smoothing (K), and background correction were investigated regarding their effect on the PSF. Experimental data were complemented by CASINO simulations. Differences in detector position between the observed particles and the method's simulated reference particles caused shifting between secondary electron PSFs and backscattered electron PSFs. Support material thickness did not have a practical effect on the PSF at the tested voltages. Uncertainty in reference particle size varied the PSF full width at half maximum (FWHM) within ±0.7 nm at 2σ, with virtually no uncertainty in some cases. K and background correction within a reasonable range of values resulted in PSF FWHM differences within ±0.9 nm, except at 2 kV for K with an upper bound of ±1.9 nm due to increased noise. Tailoring K and background correction case-by-case would result in smaller differences. The interconnection of these parameters may help in future efforts to calculate their best selection.

中文翻译：

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探索扫描电子显微镜点扩散函数确定的参数空间——上篇：对点扩散函数的影响

扫描电子显微镜 (SEM) 的点扩散函数 (PSF) 可以使用最近开发的纳米粒子校准方法来确定。PSF 确定涉及许多参数，并在 PSF 大小和形状中引入了以前未研究的不确定性。信号类型、支撑材料厚度、参考粒径、PSF 平滑（ķ)，并研究了背景校正对 PSF 的影响。实验数据由 CASINO 模拟补充。观察到的粒子和该方法的模拟参考粒子之间的探测器位置差异导致二次电子 PSF 和背散射电子 PSF 之间的偏移。在测试电压下，支撑材料厚度对 PSF 没有实际影响。参考粒径的不确定性使 PSF 半峰全宽 (FWHM) 在 ±0.7 nm 范围内变化 2σ，在某些情况下几乎没有不确定性。ķ在合理的值范围内进行背景校正导致 PSF FWHM 差异在 ±0.9 nm 内，但 2 kV 时除外ķ由于噪声增加，上限为 ±1.9 nm。剪裁ķ逐案背景校正会导致较小的差异。这些参数的相互联系可能有助于未来计算它们的最佳选择。