Application of the ion mixing method for doping near surface layers of the silicon single crystals

Abstract

Penetration of alien atoms (Be, Al, Ni, Mo) into Si, diamond monocrystals substrates was investigated under Ar⁺ ion bombardment of samples having thermally evaporated films of 30–50 nm. Sputtering was carried out using a wide energy spectrum beam of Ar⁺ ions with mean energy 9.4 keV to dose D = 1×10¹⁶–10¹⁹ ion/cm². Implanted atom distribution in the targets was measured by Rutherford backscattering spectrometry (RBS) of H⁺ and He⁺ ions with start energy of 1.6 MeV as well as secondary ion mass-spectrometry (SIMS).

During the bombardment, the penetration depth of Ar atoms increases with dose linearly. This depth is more than 3–20 times deeper than the projected range of bombarding ions and recoil atoms. This is a “ion mixing” process.

The analysis shows that the experimental data for foreign atoms penetration depth are similar to the data calculated for atom migration through the interstitial site in a field of internal (lateral) compressive stresses created in the near-surface layer of the substrate as a result of implantation. Under these experimental conditions atom ratio r _i/r _m (r _i - radius of dopant atom, r _m - radius of substrate atom) can play a principal determining role. Show that maximum penetration depth of the film atoms in the substrates may be determine by “isotropic model” under ion beam (with wide energy spectrum – polyenergy) irradiation of the “film–substrate” systems too.