US Patent 11942306 Atomic layer etching by electron wavefront

Atomic layer etching (ALE) of a substrate using a wafer scale wave of precisely controlled electrons is presented. A volume of gaseous plasma including diluent and reactive species and electrons of a uniform steady state composition is generated in a positive column of a DC plasma proximate the substrate. A corrosion layer is formed on the substrate by adsorption of the reactive species to atoms at the surface of the substrate. The substrate is positively biased to draw electrons from the volume to the surface of the substrate and impart energy to the electrons to stimulate electron transitions in the corrosion layer species, resulting in ejection of the corrosion layer species via electron stimulation desorption (ESD). The substrate is negatively biased to repel the electrons from the surface of the substrate back to the volume, followed by a zero bias to restore the steady state composition of the volume.