USE OF ELECTRON BEAM SCANNING ELECTRON MICROSCOPY FOR CHARACTERIZATION OF A SIDEWALL OCCLUDED FROM LINE-OF-SIGHT OF THE ELECTRON BEAM

摘要

The semiconductor device is scanned by an electron beam of a scanning electron microscope (SEM). The region includes a three-dimensional (3D) feature with a top opening and sidewall. The 3D feature is imaged while changing the energy value of the electron beam. The electron beam strikes a first point in a selected area of the semiconductor device and interacts with the sidewall, the first point being a distance from the edge of the top opening. When the energy value of the electron beam changes during SEM imaging, it is determined whether the sidewall is blocked from the line of sight of the electron beam based on the change in the signal representing the secondary electron yield at the edge. The slope of the sidewall can be determined by comparing the measured signals with simulated waveforms corresponding to various slopes.