Formation of SEM Images in the Secondary Electron Mode. 2. Structures with a Trapezoidal Profile and Small Side-Wall Inclinations

Abstract

The formation of images of silicon microstructures in a scanning electron microscope, operating in the modes of collecting secondary slow electrons (SSEs) and backscattered electrons (BSEs), is studied. Grooves in electronic silicon with a trapezoidal profile and small angles of inclination of the side walls with a nominal width of 1 µm and a depth of 300 nm are used as the object of study. It is shown that among four mechanisms for the formation of BSE images, currently known, only two mechanisms contribute to the formation of SSE images. They take into account the formation of an image by the primary electron probe and by multiply scattered primary and secondary electrons coming from the surface of a solid. Multiply scattered secondary electrons moving in the direction of probe electron motion, which make the main contribution to the formation of the BSE image, do not contribute to the formation of the SSE image.