MeV Al⁺ and Al₂⁺ ions implantation in Si(100): surface roughness and defects in the bulk

This paper deals with the implantation of high-energy (1.0-3.0 MeV) atomic and molecular Al⁺ ions in Si(100) to a fluence of 5 × 10¹⁴ Al atoms/cm² at room temperature. The molecular effect, i.e. the increase of the displacement yield compared with the sum of the atomic yields, and the damage formation as well as defect behaviour after annealing have been investigated. A detailed experimental study has been made of the evolution of extended secondary defects which form during thermal anneals of Al⁺ or Al₂⁺ irradiated silicon. The samples have been examined using combined Rutherford backscattering and channeling experiments together with transmission electron microscopy observations. The surface structure of the implanted wafers has been measured by atomic force microscopy. The results for the implantation-induced roughness at the Si surface, resulting from Al⁺ or Al₂⁺ irradiation at the same energy/atom, total atomic fluence, flux rate, and irradiation temperature, are presented and discussed.