具有埋层结构电介质样品扫描电镜二次电子特性

摘要

采用较为全面的考虑电子散射、俘获、输运和自洽场等过程的数值模型，阐明了具有埋层结构电介质样品的扫描电镜检测机理及二次电子电流的动态特性。模拟结果表明，被沟槽界面俘获的电荷会影响空间电场分布，从而影响二次电子特性。随着电子束照射，样品表面沿着深度方向的电场强度增强，更多的二次电子返回表面，从而产生图像衬度。图像衬度随电子束能量的变化呈现极大值，而随电子束电流的增大而增大，模拟结果与实验结果基本一致。%The scanning electron microscopic contrast mechanism and secondary electron (SE ) current characteristics are clarified for imaging a buried microstructure of the dielectric ,by applying a self-consistent numerical model that incorporating elec-tron scattering ,trapping and transport .Simulation results show that ,the trapped charges by trench interface can affect the space charges ,spaces field and consequently SE current characteristics .With irradiation ,the local electric field intensifies above the surface along z direction increase .Therefore ,more SEs can return to the surface and result in the dark image .The image results in contrast exhibits the maximum value with the beam energy ,but increases with the beam current .The simulation results are in good agreement with the experimental ones .