The mechanisms of formation of long-range profile "tails" of interstitial ions implanted into the crystalline targets are studied in detail. The role of specific over-barrier states (metachanneling) in the formation of a long-range fraction of the beam implanted in the crystal off the stable channeling conditions is determined. Analytic expressions for new critical angles bounding the regions with observed directional effects in the ion implantation were obtained. Theoretical predictions of the developed model are in the qualitative accord with the data of computer experiments accomplished (see Fig.1).
Fig.1 – Radial projection of the distribution of probabilities of anomalous penetration of boron and arsenic ion into the crystalline silicon depending on the conditions of the beam incidence onto the (001) face
The introduced critical angles restrict the regions of orientation effects revealed in the ion range distributions and can be used for determination of optimum implantation conditions