Numerical Simulation of Atomic Layer Oxidation of Silicon by Oxygen Gas Cluster Beams

Abstract

A gas cluster is a collection of atoms or molecules weakly bound by van der Waals forces. Gas clusters may form by the adiabatic expansion of gases. In this study, it is demonstrated by molecular dynamics simulations that a low-energy beam of oxygen gas clusters may be used to oxidize the top surface layer of silicon (Si) substrates without affecting its deeper layers. An incident oxygen gas cluster with sufficiently low incident energy may stick to the Si surface and expose a large number of oxygen molecules to the surface Si atoms for extended periods until the cluster sublimates. This may cause the formation of Si-O bonds only on the top Si surface. This is in contrast to the oxidation of Si by oxygen ion beams or plasmas, where deeper layers of the Si surface are typically oxidized by the energetic incident oxygen ions. An oxidized single Si layer may be chemically removed; therefore, this nearly single-layer oxidation process by oxygen gas cluster beams may lead to the development of a new atomic layer etching technology for Si.

Correlation between dry etching resistance of Ta masks and the oxidation states of the surface oxide layers

“…It is known that incident ions with an oblique angle of incidence are more likely to be reflected from the surface than those of normal incidence. Detailed analyses of surface oxidation processes by incident oxygen ions or atoms, including theoretical studies with molecular dynamics simulations, 35 are deferred to a future study.…”