Molecular dynamics and Monte-Carlo simulation of sputtering and mixing by ion irradiation

Molecular dynamics (MD) and Monte-Carlo (MC) simulations of low-energy (< 5 00 eV) Ar ion irradiation on Si substrates were performed in order to inves tigate the mixing and sputtering effects. Both MD and MC simulation show si milar results in sputtering yield. depth profile of projectile and mixing o f substrate. For these incident energies, the depth of the mixed region is determined by the implant range of incident ions. For example, when the inc ident energy is 500 eV, the Ar ions reach a depth of 40 Angstrom so that th e Si atoms that reside shallower than 40 Angstrom are fully mixed at an ion dose of about 5.0 x 10(16) atoms/cm(2). The resolution of secondary ion ma ss spectrometry (SIMS) was also studied. It was found that the resolution o f SIMS depends on the depth of mixing, which depends in turn on the implant range of the probe ions. This is because the mixing of substrate atoms occ urs more frequently than sputtering, so that the information about the dept h profile in the mixing region is disturbed. (C) 2001 Elsevier Science B.V. All rights reserved.