Molecular dynamics simulation of helium ion implantation into silicon and its migration

Abstract

In this paper, a model of helium ion implanted monocrystalline Si was constructed by using molecular dynamics (MD) simulation method to study the interaction mechanism of helium ion with monocrystalline Si and helium ion migration. In order to study the damage effect of helium ion implantation on monocrystalline Si, identify diamond structure (IDS), radial distribution function, temperature analysis were calculated and analyzed. The effects of ion doses, beam currents and energies on the damage were studied. Helium ion implanted Si with ion doses of 1 × 1014/cm2 was subsequently heated to 300 K. MD simulation results indicated that IDS damage induced by ion implantation was positively correlated with ion doses as the ion implantation increased to 1 × 1014/cm2. The mean-square displacement of helium atoms was calculated during the temperature rising to 300 K. It was found that the high permeability of helium atoms in Si and the acceleration of atomic thermal motion owing to elevated temperature as well as the existence of larger stress would be helpful to the migration of implant helium atoms.