Mechanism of electron multiplication due to charging for a SiO2sample with a buried microstructure in SEM: A simulation analysis.
This study investigates the mechanism of electron redistribution and multiplication for a SiO2sample with a buried structure in scanning electron microscopy by numerical simulation. The simulation involved electron scattering and internal charge transport in the sample, the tracking of emitted secondary electrons (SEs), and the generation of tertiary electrons (TEs) produced by returned SEs due to charging of the sample. The results show that a buried grounded structure causes a non-uniform distribution of surface potential, and an electric field above the surface. As a result, although the number of escaped SEs above the margin of the buried structure decreases, the number of generated TEs increases more, leading to a final current of electrons that include escaped SEs and increased TEs. This multiplication of SEs might make a crucial contribution to the abnormal negative-charging contrast in SEM. During the electron beam irradiation, the variation in the number of total escaped electrons presents an obvious increase after an initial slight decrease, which corresponded to the transient characteristics of gray levels in SEM images from dark to abnormally bright.
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China.
Fang
F
Wang
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; National Key Laboratory on Space Microwave Laboratory, China Academy of Space Technology, Xi'an 710100, PR China.
Guobao
G
Feng
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China.
Xiusheng
X
Zhang
Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China. Electronic address: mengcao@mail.xjtu.edu.cn.
Meng
M
Cao
Electron multiplication; Insulator charging; Numerical simulation; Surface potential