Belkorissat R, Kadoun A, Khelifa B, Mathieu C
Laboratoire d'Elaboration et de Caractérisation des Matériaux, Université Djilali Liabès de Sidi Bel-Abbes, BP 89, 22000 Sidi Bel-Abbès, Algeria.
Micron. 2004;35(7):543-7. doi: 10.1016/j.micron.2004.03.003.
Helium gas and air are commonly used in the high pressure scanning electron microscope (HPSEM). The presence of a gaseous environment in the specimen chamber modifies the electron beam profile. In order to fully understand the beam-gas interaction, we have investigated the beam-diameter effect for two gases (helium and air) by Monte Carlo simulation. In this calculation, we have assumed that the electron beam is Gaussian and we have explored the influence of the nature of the gas at low voltage. When the beam diameter varies between 1 and 100 nm, there is no influence on the beam profile for these two gases. The resolving power of the HPSEM is not affected by the beam-gas interaction. These theoretical results have been compared with experimental images obtained at low voltage under air and helium gases. The variation of image quality at low voltage has confirmed the interest of helium for use in a Field Emission Gun SEM (FEGSEM) in high pressure (or low vacuum) conditions.
氦气和空气常用于高压扫描电子显微镜（HPSEM）中。样品室中气态环境的存在会改变电子束轮廓。为了全面理解束流与气体的相互作用，我们通过蒙特卡罗模拟研究了两种气体（氦气和空气）的束径效应。在该计算中，我们假设电子束为高斯束，并探讨了低电压下气体性质的影响。当束径在1至100纳米之间变化时，这两种气体对束轮廓没有影响。HPSEM的分辨能力不受束流与气体相互作用的影响。这些理论结果已与在空气和氦气中低电压下获得的实验图像进行了比较。低电压下图像质量的变化证实了氦气在高压（或低真空）条件下用于场发射枪扫描电子显微镜（FEGSEM）的优势。
