Diffusivity in Silicon 1953 to 2009 Diffusivity in Silicon 1953 to 2009 Editor: D.J. Fisher TRANS TECH PUBLICATIONS LTD Switzerland • UK • USA Copyright © 2010 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of the contents of this book may be reproduced or transmitted in any form or by any means without the written permission of the publisher. Trans Tech Publications Ltd Laubisrutistr. 24 CH-8712 Stafa-Zuerich Switzerland http://www.ttp.net Volume 302 of Defect and Diffusion Forum ISSN 1012-0386 (Pt. A of Diffusion and Defect Data – Solid State Data ISSN 0377-6883) Full text available online at http://www.scientific.net Distributed worldwide by and in the Americas by Trans Tech Publications Ltd Trans Tech Publications Inc. Laubisrutistr. 24 PO Box 699, May Street CH-8712 Stafa-Zurich Enfield, NH 03748 Switzerland USA Phone: +1 (603) 632-7377 Fax: +41 (44) 922 10 33 Fax: +1 (603) 632-5611 e-mail: [email protected] e-mail: [email protected] Web: http://www.ttp.net Table of Contents Abstracts 1 Abstracts [1] Ag Bulk Diffusion It was found that the Ag diffusivity at between 1100 and 1350C could be described by: D(cm2/s) = 2 x 10-3exp[-1.6(eV)/kT] B.I.Boltaks, S.Y.Hsueh: Soviet Physics - Solid State, 1961, 2, 2383 [2] Ag Bulk Diffusion Radioactive tracer methods were used to study diffusion in polycrystalline samples. It was found that the results between 1000 and 1200C could be described by: D(cm2/s) = 4.05 x 100exp[-3.04(eV)/kT] V.P.Prutkin, A.S.Lyutovich, M.J.Kardzhaubaev: Krist. Tonkikh Plenok, 1970, 139-45 [3] Ag: Bulk Diffusion Transition metals in amorphous samples exhibit a direct interstitial diffusion behavior which is retarded by temporary trapping at defects that are intrinsic to the amorphous structure. Diffusion was investigated here by means of Rutherford back-scattering spectrometry. It was found that the data (table 1) could be fitted by using foreign- atom interstitial diffusion coefficients for crystalline Si; modified by the presence of traps in concentrations of between 0.2 and 1at%, and with trapping enthalpies of about 0.9eV. The results could be expressed as: D (cm2/s) = 1.6 x 10-1exp[-1.67(eV)/kT] Determination of Diffusion Mechanisms in Amorphous Silicon. S.Coffa, J.M.Poate, D.C.Jacobson, W.Frank, W.Gustin: Physical Review B, 1992, 45[15], 8355-8 Table 1 Diffusivity of Ag in Amorphous Si Temperature (C) D (cm2/s) 485 1.2 x 10-12 400 4.2 x 10-14 355 4.1 x 10-15 305 4.5 x 10-16 [4] Ag Bulk Diffusion 2 Diffusivity in Silicon 1953 to 2009 The migration of Ag from epitaxial layers and into (111) samples of Si, during annealing at temperatures of between 450 and 500C, was studied by means of secondary ion mass spectrometric depth profiling. It was found that the diffusivities lay between 8 x 10-16 and 1.6 x 10-15cm2/s (table 2). These values were lower than were expected on the basis of previous data. Study of Silver Diffusion into Si(111) and SiO2 at Moderate Temperatures. T.C.Nason, G.R.Yang, K.H.Park, T.M.Lu: Journal of Applied Physics, 1991, 70[3], 1392-6 Table 2 Diffusion of Ag into (111)Si Temperature (C) Surface Concentration(/cm3) D (cm2/s) 450 6.5 x 1019 1.5 x 10-15 450 2.9 x 1019 8.0 x 10-16 500 4.0 x 1020 1.6 x 10-15 [5] Ag Bulk Diffusion Concentration versus depth profiles of Ag were measured by using neutron activation analysis and serial sectioning. The Ag diffusion appeared to be very fast. In the bulk of dislocation-free wafers, saturation was achieved after short periods of annealing. From this, it was concluded that interstitial Ag was the predominant configuration in Si without dislocations. Equilibrium concentrations of Ag were determined for temperatures of between 1287 and 1598K. The results were thermodynamically analyzed, taking account of Ag-Si liquidus data. In dislocated Si, much higher Ag concentrations were found which varied irregularly with penetration depth. A comparison of the diffusion and solubility of Ag and Au in Si suggested that, in material with dislocations, substitutional Ag could arise from Agi-Ags transitions. Finally, the Agi diffusivity was deduced to be given by: D(cm2/s) = 6 x 10-1 exp[-1.15(eV)/kT] Solubility, Diffusion and Thermodynamic Properties of Silver in Silicon. F.Rollert, N.A.Stolwijk, H.Mehrer: Journal of Physics D, 1987, 20[9], 1148-55 [6] Ag Bulk Diffusion The lattice location of implanted Ag was studied using emission channelling. Following the room-temperature implantation of 60keV radioactive 111Ag to doses of 2 x 1012 to 3 x 1012/cm2, the presence of some 30% of Ag on near-substitutional sites (about 0.045nm from ideal substitutional sites) was revealed. Upon annealing at 200 to 300C, the fraction on near-substitutional sites attained a maximum of around 60 to 80%. At higher annealing temperatures it decreased again and, at 600C, the Ag started to diffuse out of the samples. The activation energy for the dissociation of David J. Fisher 3 near-substitutional Ag was estimated to be 1.8 to 2.2eV. The experimental results were compared with those for Cu in Si, and common features and differences were noted in the behaviors of the 2 group-IB metals. Lattice Location of Implanted Ag in Si. U.Wahl, J.G.Correia, A.Vantomme, Isolde: Nuclear Instruments and Methods in Physics Research B, 2002, 190[1-4], 543-6 [7] Ag Bulk Diffusion An in situ low-angle X-ray diffraction technique was used to investigate interdiffusion in Ag/amorphous-Si nm-scale compositionally modulated multi-layers. The interdiffusivities were deduced by monitoring the decay of the first-order modulation peak as a function of annealing time. The results for interdiffusion in the Ag/Si multi-layers were described by: D (cm2/s) = 2.02 x 10-16exp[-0.24(eV)/kT] Interdiffusion in Nanometer-Scale Multilayers Investigated by in situ Low- Angle X-Ray Diffraction W.H.Wang, H.Y.Bai, M.Zhang, J.H.Zhao, X.Y.Zhang, W.K.Wang: Physical Review B, 1999, 59[16], 10811-22 [8] Ag Pipe Diffusion Using the radioactive isotope, 110Ag, diffusion along dislocations was studied. It was found that the results at between 800 and 1000C could be described by: D(cm2/s) = 1.5 x 100exp[-1.39(eV)/kT] V.A.Sterkhov, V.A.Panteleev, P.V.Pavlov: Fizika Tverdogo Tela, 1967, 9[2], 681-3 [9] Ag Surface Diffusion Mass transport on the (111) surface was studied by means of scanning electron microscopy and Auger analysis (with spatial resolution) under ultra-high vacuum conditions. The spreading of Ag deposits was investigated at temperatures ranging from 350 to 450C; where no desorption occurred. In order to avoid electromigration, the samples were heated by using a halogen lamp. When the first islands had formed (Stranski-Krastanov growth), Ag began to spread out of the initial deposit zone. The main features deduced from the concentration profiles were that, at temperatures above about 400C, the profiles exhibited a rather constant concentration that ended in a very sharp front (attributed to an unrolling carpet mechanism). At temperatures below about 400C, the corresponding profiles had 2 gradient zones. In both cases, a t ¾ kinetic law was found which suggested that Ag/Si mass transport might be controlled by the surface self-diffusion of Ag atoms, on 3-dimensional Ag islands, with an activation energy of about 2.4eV/atom. Ag Mass Transport on Si(111) in the 350–450°C Temperature Range. N.Boutaoui, H.Roux, M.Tholomier: Surface Science, 1990, 239[3], 213-21 4 Diffusivity in Silicon 1953 to 2009 [10] Ag Surface Diffusion By using ab initio total-energy calculations, a study was made of the adsorption and diffusion of Ag atoms on a dimer-reconstructed Si(001) surface. For a single Ag adsorption, the 2-fold-coordinated cave site above the fourth Si layer atom was found to be the most stable; in agreement with previous work. Inspection of the electronic structures at the cave site revealed that the Ag-Si bonds originated from low-lying 4d electrons and were covalent. The calculations also revealed another stable adsorption at the pedestal site that was slightly higher by 0.03eV in energy than the cave site. Further potential-energy-surface calculations showed that the surface diffusion of a single Ag adatom was unexpectedly highly isotropic and that the energy barrier was 0.5eV. When more Ag adatoms were adsorbed on the Si surface, the Ag adatoms were expected to form dimers. Actually, an energy gain of 0.36eV/dimer was obtained through the dimerization. The diffusion of an Ag dimer was also investigated. Surprisingly, a very rapid surface-dimer diffusion was found; with an energy barrier of 0.48eV. This was slightly lower than that of the single Ag adatom. In contrast to the diffusion of the single Ag adatom, the dimer diffusion was anisotropic and preferably occurred along the valley between Si dimer rows by concerted flip-flop processes. Ab initio Study of Adsorption and Diffusion of Ag Atoms on a Si(001) Surface. K.Kong, H.W.Yeom, D.Ahn, H.Yi, B.D.Yu: Physical Review B, 2003, 67[23], 235328 (7pp) [11] Al Bulk Diffusion It was found that the Al diffusivity at between 1085 and 1375C could be described by: D(cm2/s) = 8 x 100exp[-3.47(eV)/kT] Retrograde Solubility of Aluminum in Silicon. D.Navon, V.Chernyshov: Journal of Applied Physics, 1957, 28, 823 [12] Al Bulk Diffusion It was found that the Al diffusivity at between 1050 and 1380C could be described by: D(cm2/s) = 4.8 x 100exp[-3.36(eV)/kT] Diffusion of Aluminum in Single Crystal Silicon. R.C.Miller, A.Savage: Journal of Applied Physics, 1956, 27, 1430 [13] Al Bulk Diffusion It was found that the Al diffusivity at between 1200 and 1400C could be described by: D(cm2/s) = 2.8 x 103exp[-3.8(eV)/kT] B.Goldstein: Bulletin of the American Physical Society, 1956, 1, 145