On the state of Mn impurity implanted in Si
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RACTION AND SCATTERING OF IONIZING RADIATIONS
On the State of Mn Impurity Implanted in Si A. F. Orlova, V. T. Bublikb, V. I. Vdovinc, Yu. A. Agafonovd, L. A. Balagurova, V. I. Zinenkod, I. V. Kulemanova, and K. D. Shcherbachevb a
State Institute for Rare Metals, Moscow, 119017 Russia email: [email protected] b Moscow State Institute of Steel and Alloys, Leninskiі pr. 4, Moscow, 119049 Russia c Institute for Chemical Problems of Microelectronics, Moscow, 119017 Russia d Institute of Microelectronics, Technology, and High Purity Materials, Russian Academy of Sciences, Chernogolovka, Moscow region, 142432 Russia Received December 24, 2008
Abstract—The state of manganese impurity in implanted silicon at implantation doses of up to 5 × 1016 cm–2 has been investigated by Xray diffraction and transmission electron microscopy. It is established that, after short term vacuum annealing at 850°C, most of the implanted manganese impurities are in microinclusions up to 20 nm in size formed by a tetragonal silicide phase of the Mn15Si26 type. PACS numbers: 61.05.cp; 61.05.jm; 68.37.Lp DOI: 10.1134/S1063774509040038
INTRODUCTION In the last few years, singlecrystal silicon implanted by manganese is of large interest in view of its potential use in semiconductor spin electronics devices. Ferromagnetic ordering was observed at room temperature in thin Si films with Mn impurities and silicon wafers implanted by Mn [1–6]. However, in [7, 8], ferromagnetic ordering in such a system was observed only at low temperatures and was attributed to the existence of nanocrystalline inclusions of the intermetallic phase of an MnSi1.7 type in Mn implanted silicon. The conclusion about the state of Mn impurities in Si was drawn in these studies on the basis of an analysis of Xray diffraction data and the fine structure of Xray absorption spectra of impurity atoms. Recently, when investigating the resistivity dis tribution in Si wafers implanted by Mn, it was estab lished that only a small fraction of the Mn impurities (about 1%) is electrically active and incorporated into the silicon lattice. In this study, an attempt was made to establish the state of most Mn impurities implanted into singlecrystal silicon wafers, which exhibit ferro magnetic ordering at room temperature after implan tation. EXPERIMENTAL Standard wafers prepared from nSi(100) and n Si(111) single crystals with resistivities of 0.01 and 4.5 Ω cm, grown by the Czochralski method, were chosen for implantation. 195keV 55Mn+ ions were implanted to doses of 5 × 1015 and 5 × 1016 cm–2 on an Extrion 2001000 system (Varian) at a temperature of
350°С. After implantation, the samples were subjected to shortterm vacuum annealing for 5 min at 850°С to eliminate amorphization effects. Ferromagnetic ordering has been previously observed in such samples at room temperature [6]. The Xray diffraction spectra were measured on a D8 Discover multifunctional dif fractometer (BrukerAXS) in low resolution using CuKα radiation. A long Soller slot and nickel filter were installed bef
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