Correlated out-diffusion of nitrogen and in-diffusion of self-interstitials resulting in elimination of nitrogen-related deep centres

Annealing of nitrogen-doped silicon is known to produce deep donors. Prolonged annealing leads to a donor-depleted region that quickly propagates from the surface into the bulk. This effect is very similar to propagation of the region depleted of the substitutional nitrogen evidenced by the depth profile of the total nitrogen. Both effects result from annihilation of the substitutional nitrogen by self-interstitials (I) produced by emission when the out-diffusing interstitial trimers N3 are incorporated into the surface nitride film. The basic source of N3 is the reaction I + VN3 → N3. The I species are consumed by this reaction, but then produced in a greater amount by the created trimers.