Quantum-statistical Analysis of Low Energy Sputtering

Abstract

Low energy surface sputtering of polycrystalline metals is explained theoretically by means of a three-body sputtering mechanism involving the impinging ion and two metal atoms. By means of quantum-statistical methods, a formula for the number S(E) of atoms sputtered on the average by an ion of energy E is derived from first principles. The theory agrees with experimental sputtering data in the low energy region above the threshold. As an application, mercury-metal atom scattering cross sections are determined by quantitative comparison of the theoretical and experimental S(E) values for sputtering mercury ions from various metals.

Experimental and Modeling Studies of Low Energy Ion Sputtering in Ion Thrusters

“…Wilhem [28] developed a model appropriate for predicting sputtering yield at energies near threshold. His model is not dependent on binary collisions like Sigmund Formula.…”

“…In order to estimate the error of the measured sputtering yield associated with the doubly charged ion content and energy spread of the beam, a calculation was derived using Eq. 3.16, the Wilhelm formula [28] for calculating sputtering yields, as adapted for xenon-molybdenum systems by Mantenieks [29]. The measured sputtering yield, Y m , in an experiment using an ion beam with a doubly charged ion flux coefficient n d and an ion energy distribution with standard deviation σ is approximated as…”

Calculation of Boron Nitride Sputter Yields Under Low Energy Xenon Ion Bombardment

“…A quantum-statistical approach presented by Wilhelm is also used for comparison of the sputter yields at very low energies. 27 A three-body interaction of the ion and two atoms of a polycrystalline solid is considered, and the probabilities of the ion scattering versus an atom sputtering are used to calculate the rate of sputter. Wilhelm's approximation for the sputter yield at energies between the threshold energy and about 100 eV is given by…”

Modeling low energy sputtering of hexagonal boron nitride by xenon ions

“…As the xenon ions are assumed to be neutralized by an electron from the surface before impact, electrostatic effects do not need to be considered and the xenon particles are modeled as neutral atoms. 23 Also, since the van der Waals attraction of the xenon with the boron and nitrogen atoms is much weaker than the covalent bonding in the boron nitride, a purely repulsive potential is acceptable. 24 The Molière potential function, a common choice for ion impact studies, is chosen for the xenon ion interactions in this work.…”