The paper reports that using IR-spectroscopy technique, it has been revealed that nickel atoms in the silicon lattice are gathered in clusters, i.e., the phenomenon of selfassembly takes place. The concentration and dimension of the clusters are mainly defined by the temperature of diffusion and the cooling rate. The composition of clusters of nickel impurity atoms was determined. It was shown that in the process of thermal annealing within the temperature range 650…900 °С there is a significant change in the state, concentration and size of clusters. Thermal annealing at the above temperatures 650…900 °С leads to ordering the clusters that is, self-assembly of cluster blocks, as well as clusters of a loop shape that includes several dozens of clusters. A diffusion technique to form and order clusters of nickel atoms in silicon has been suggested.