Analysis of Surface Morphology and Chemical Composition of Silicon Implanted with Copper Ions
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ICAL SCIENCE OF MATERIALS
Analysis of Surface Morphology and Chemical Composition of Silicon Implanted with Copper Ions V. V. Vorob’eva,b, A. I. Gumarova,b,*, L. R. Tagirova,b, A. M. Rogova,b, V. I. Nuzhdinb, V. F. Valeevb, and A. L. Stepanovb a Institute
b
of Physics, Kazan Federal University, Kazan, 420008 Russia Zavoisky Physical Technical Institute, Federal Research Center Kazan Scientific Center, Russian Academy of Sciences, Kazan, 4200029 Russia *e-mail: [email protected] Received January 24, 2020; revised March 12, 2020; accepted March 31, 2020
Abstract—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 × 1015– 1.25 × 1017 ions/cm2 for a current density of 8 μA/cm2 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 × 1016 ions/cm2 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 × 1017 ions/cm2 and higher, the nucleation of the η phase of copper silicide (η-Cu3Si) 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 η-Cu3Si phase. DOI: 10.1134/S1063784220100242
INTRODUCTION Various technological methods used in practice for the implantation or deposition of the Cu impurity for a targeted modification of the surface properties of c-Si change the morphology, the phase composition of the surface, as well as electrochemical, electric, and optical characteristics of Si. Such technologies include, for example, immersion chemical deposition of Cu from the CuSO4 ⋅ 5H2O solution on the plane wafer surface or on a porous Si (PSi) layer [1], which leads to the coating of Si with an almost continuous layer of Cu nanoparticles of a size of ~10 nm. Another approach to PSi modification is the electrochemical deposition of Cu nanoparticles from colloidal solution on the sample surface [2]. In these publications, partial oxidation of Cu nanoparticles was observed without the formation of any copper silicide phase. In addition to chemical deposition of Cu on Si, a physical method of implantation of metal impurities (e.g., ion implantation) is used [3]. It is well known that this approach is widely employed in semiconductor technology in fabrication of electronic devices [4]. Apparently, publication [5], in which the implantation of Si was performed with relatively small doses (D < 5 × 1015 ions/cm2), was one of the first works on implantation of Cu+ ions into Si.
In this study, we have carried out experiments on the implantation of c-Si single-crystal substrate by Cu+ ions with energy of 40 keV in various doses D for estimating the possibility of Cu nanoparticles controllable formation in
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