Simulations of scanning electron microscopy imaging and charging of insulating structures
Simulations of scanning electron microscopy imaging and charging of insulating structures
复制标题
DOI：
10.1002/sca.4950250606
复制
发表时间：
2003-11-01
期刊：
影响因子：
--
通讯作者：
Adler, DL
中科院分区：
文献类型：
--
作者：
Grella, L;Lorusso, G;Adler, DL
我们提出了 anninR 电子显微镜 (SEM) 图像和表面充电的三维模拟。首先，使用拉普拉斯方程在适当的边界条件下计算样本上方的场：然后。模拟算法开始使用电子射线追踪来跟踪样品外部的电子轨迹。当电子与样本碰撞时，算法通过使用蒙特卡罗代码模拟电子散射历史来跟踪样本内的电子。在此阶段，发射二次和背散射电子以形成图像，并且一次电子被吸收，因此在材料中形成电荷密度。通过使用适当的边界条件求解泊松方程，该电荷密度用于重新计算样品上方和内部的场。场方程，蒙特卡罗散射模拟。因此，电子射线追踪以自洽的方式集成，形成能够模拟绝缘结构充电和成像的算法。为了保持通用性，该算法在三个维度上实现。我们将应用如此定义的模拟来计算扫描光束引起的全局表面电压和局部微场。此外。我们将展示充电如何影响分辨率和图像形成，以及当成像参数改变时其特性如何变化。我们将讨论放大倍数、扫描策略和应用领域。结果。与实验相比，清楚地表明必须包括充电和适当的边界条件才能模拟绝缘特征的图像。此外，我们将证明三维实现对于理解局部场形成是必需的。
We present a three-dimensional simulation of,anninR electron microscope (SEM) images and surface charging. First, the field above the sample is calculated using Laplace's equation with the proper boundary conditions: then. the simulation algorithm starts following the electron trajectory outside the sample by using electron ray tracing. When the electron collides with the specimen, the algorithm keeps track of the electron inside the sample by simulating the electron scattering, history with a Monte Carlo code. During this phase, secondary and backscattered electrons are emitted to form an image and primary electrons are absorbed, therefore, a charge density is formed in the material. This charge density is used to recalculate the field above and inside the sample by solving the Poisson equation with the proper boundary conditions. Field equation, Monte Carlo scattering simulation. and electron ray tracing are therefore integrated in a self-consistent fashion to form an algorithm capable of simulating charging and imaging of insulating structures. To maintain generality, this algorithm has been implemented in three dimensions. We shall apply the so-defined simulation to calculate both the global surface voltage and local microfields induced by the scanning beam. Furthermore. we shall show how charging affects resolution and image formation in general and how its characteristics change when imaging parameters are changed. We shall address magnification, scanning strategy and applied field. The results. compared with experiments, clearly indicate that charging and the proper boundary conditions must be included in order to simulate images of insulating features. Furthermore, we shall show that a three-dimensional implementation is mandatory for understanding local field formation.