Spin-split scanning electron microscope

Abstract

A spin-split scanning electron microscope (SSSEM) uses a spin-split electron beam interferometer to measure the difference between two electron beam paths. By measuring the difference in path lengths, and/or measuring changes in the relative difference between the two paths as the electron beams are scanned over a surface, the topology of an object's surface may be measured. The measuring changes in the relative difference between the two paths as a material etching or material deposition or growth process is performed, the amount of material added or removed from an object's surface may be metered. The spin-split scanning electron microscope includes an electron beam source that generates a flying stream of electrons, a spin-split electron beam splitter splits the flying stream of electrons into first and second electron beams having different trajectories, an electron beam intensity detector that receives a reflected portion of the first and second electron beams after they have been reflected from distinct positions of a target surface and generates an intensity signal indicative of the received beams combined intensity; and a controller coupled that receives the intensity signal, and analyzes changes in the intensity signal to determine relative changes in path lengths of the first and second electron beams. The beam splitter includes a magnetic field generator that generates a non-uniform magnetic field in region of space intercepted by the flying stream of electrons which causes electrons having opposite magnetic moments to be deflected into two separate electron beams.