扫描电镜样品表面残留电位均匀化的机理研究/Mechanism Study of Surface-Potential Initialization for a S
The charge accumulation near the sample surface will produce remained non-uniform potential after e-beam irradiation in a SEM.
This remained potential can disturb the voltage and charging
contrast and even cause the abnormal contrast. Therefore, it is important for the reproducible observation and study of charging contrast to initialize the surface potential, i.e. erase the accumulated charge. The influence of the remained potential on
SEM image contrast is analyzed firstly. For the experimental results of initializing the remained potential by low voltage e-beam scanning, a numerical model is built to calculate the surface potential varying with the charge accumulation near the insulator surface during the scanning irradiation process. The computed results show the proportion of the secondary electrons returning to the surface changes with the surface potential. The potential rises at the area in which the remained potential is less than the steady-state voltage and
decreases at the higher potential area because of the effect of the primary electrons, secondary electrons that returned to the surface and the holes. The differences of the surface potentials are lowered with the scanning time and the surface-potential initialization can