Monte Carlo simulation of scanning electron microscope image of sidewall shape for linewidth measurement

Scanning electron microscope (SEM) has been an important tool for the observation of surface micro-structures of various kinds of materials. The secondary electron image, which uses secondary electrons that escaped from the surface under a primary electron beam bombardment as imaging signals, can provide the surface topographic information with a resolution up to sub-nm with a modern SEM. Therefore, it can be used for nanometrology with improved measurement accuracy by critical dimension scanning electron microscope (CD-SEM). This work aims to develop a Monte Carlo simulation method for application to the nanometer linewidth measurement for semiconductor devices by SEM. The simulation will provide a theoretical analysis of the influence of various parameters of specimen and electron beam on the estimation of linewidth and the sidewall angles. The result will be helpful for the improvement of the measurement precision by CD-SEM.