Chapter 5.3 - Ion Beam Technology

Abstract

Ion beam sputtering is fundamentally a momentum transfer process between the incident ions and the target atoms. The sputter yield is the number of sputtered atoms per incident ion and is a function of the ion energy, ion species and mass, target atom species and mass, and incidence angle. To eject an atom from the target surface, kinetic energy greater than the chemical binding energy of the atom must be imparted to the atom. Ion energy thresholds to impart this amount of energy range from 10 to 100 eV, depending on the material. In ion beam sputter deposition, the ion beam is directed at a target, and sputtered atoms are deposited onto a nearby substrate surface. The energy of the sputtered atoms as they leave the target ranges from a few up to tens of eV. Because of the low-pressure regime of ion beam processing, where the mean free path is on order of a meter, these sputtered atoms arrive at the substrate with most if not all of their original kinetic energy.