Analysis of surface morphology and chemical composition of silicon implanted with copper ions

We report on the results of analysis of the structure and chemical composition of the surface of $c$-Si single crystal substrates implanted with Cu$^+$ ions with energy of 40 keV and doses in a range of 3.1 $\times$ 10$^{15}$ – 1.25 $\times$ 10$^{17}$ ions/cm$^2$ for a current density of 8 $\mu$A/cm$^2$ in the ion beam. It has been established using scanning electron microscopy and probe microscopy combined with X-ray photoelectron and Auger spectroscopy that at the initial stage, the implantation with Cu$^+$ ions to a dose of 6.25 $\times$ 10$^{16}$ ions/cm$^2$ induces the formation of Cu nanoparticles with an average size of 10 nm in the Si surface layer. Upon a further increase in the implantation dose, beginning with 1.25 $\times$ 10$^{17}$ ions/cm$^2$ and higher, the nucleation of the $\eta$ phase of copper silicide ($\eta$-Cu$_{3}$Si) is observed. This is due to heating of the surface layer of the Si substrate during its irradiation to a temperature facilitating the formation of the $\eta$-Cu$_{3}$Si phase.