Investigation of the inhibiting outdiffusion of erbium atoms to a silicon-on-insulator surface after annealing at high temperature

The annealing behaviour of 400 keV Er ions at a fluence of 2 × 10¹⁵ cm^-2 implanted into silicon-on-insulator (SOI) samples is investigated by Rutherford backscattering spectrometry of 2.1 MeV He²⁺ ions with a multiple scattering model. It is found that the damage close to the SOI surface is almost removed after being annealed in O₂ and N₂ atmospheres, successively, at 900 ℃, and that only a small number of the Er atoms segregated to the surface of the SOI sample, whereas a large number of Er atoms diffused to a deeper position because of the affinity of Er for oxygen. For the SOI sample co-implanted with Er and O ions, there is no evident outdiffusion of Er atoms to the SOI surface after being annealed in N₂ atmosphere at 900 ℃.