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Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5 × 10[sup 12] to 1 &times 10[sup 14]/cm² evolves into a distribution of {311} interstitial agglomerates during the initial annealing stages at 670815 °C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the dissolution of {311} defects during Ostwald ripening with an activation energy of 3.8±0.2 eV. The excess interstitials drive substitutional B into electrically inactive, metastable clusters of presumably two or three B atoms at concentrations below the solid solubility, thus explaining the generally observed immobile B peak during TED of ion-implanted B. Injected interstitials undergo retarded diffusion in the MBE-grown Si with an effective migration energy of ∼3.5 eV, which arises from trapping at substitutional C. The concept of trap-limited diffusion provides a stepping stone for understanding the enormous disparity among published values for the interstitial diffusivity in Si. The population of excess interstitials is strongly reduced by incorporating substitutional C in Si to levels of ∼10[sup 19]/cm³ prior to ion implantation. This provides a promising method for suppressing TED, thus enabling shallow junction formation in future Si devices through dopant implantation. The present insights have been implemented into a process simulator, allowing fo... [ABSTRACT FROM AUTHOR]

Deals with a study which investigated the effects of low-dose ion implants with silicon, neon and fluorine on the transient enhanced diffusion of boron in silicon after annealing at high temperature. Background to the study; Experimental procedures; Results and discussion.

We have measured the evolution of the excess-vacancy region created by a 2 MeV, 10[sup 16]/cm[sup 2] Si implant in the silicon surface layer of silicon-on-insulator substrates. Free vacancy supersaturations were measured with Sb dopant diffusion markers during postimplant annealing at 700, 800, and 900 °C, while vacancy clusters were detected by Au labeling. We demonstrate that a large free vacancy supersaturation exists for short times, during the very early stages of annealing between the surface and the buried oxide (1 μm below). Afterwards, the free vacancy concentration returns to equilibrium in the presence of vacancy clusters. These vacancy clusters form at low temperatures and are stable to high temperatures, i.e., they have a low formation energy and high binding energy. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Measurements of the binding energy (E[sub b]) of vacancies to vacancy clusters formed in silicon following high-energy ion implantation are reported. Vacancy clusters were created by 2 MeV, 2×10[sup 15] cm[sup -2] dose Si implant and annealing. To prevent recombination of the excess vacancies (V[sup ex]) with interstitials from the implant damage near the projected range (R[sub p]), a Si-on-insulator substrate was used such that the R[sub p] damage was separated from the V[sup ex] by the buried oxide (BOX). Two V[sup ex] regions were observed: one in the middle of the top Si layer (V[sub 1][sup ex]) and the other at the front Si/BOX interface (V[sub 2][sup ex]). The rates of vacancy evaporation were directly measured by Au labeling following thermal treatments at temperatures between 800 and 900 °C for times ranging from 600 to 1800 s. The rate of vacancy evaporation from V[sub 2][sup ex] was observed to be greater than from V[sub 1][sup ex]. The binding energy of vacancies to clusters in the middle of the silicon top layer was 3.2±0.2 eV as determined from the kinetics for vacancy evaporation. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Detection and gettering of Co contamination in processed Si is an important issue in integrated circuit fabrication. In this work, Co was intentionally introduced into Si by ion implantation, and its diffusion monitored by secondary ion mass spectroscopy. The surface layer recombination lifetime in p/p[sup +] epitaxial Si is unaffected by the Co at doses of 1x10[sup 11] cm[sup -2] or 1x10[sup 12] cm[sup -2]. In the case of 2.5 MeV, 4x10[sup 14] B/cm[sup 2] ion implanted bulk Si, two mechanisms for Co redistribution during high temperature furnace, 900 °C, 30 min, processing are evident. First, regions of high boron concentration provide gettering sites for Co contamination. Second, the final distribution of Co in Si reflects ion-implantation induced defect evolution during annealing. Both mechanisms will operate during device processing and will control the effect of the metal on the electrical properties of the Si. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

It has been shown recently that Au labeling [V. C. Venezia, D. J. Eaglesham, T. E. Haynes, A. Agarwal, D. C. Jacobson, H.-J. Gossmann, and F. H. Baumann, Appl. Phys. Lett. 73, 2980 (1998)] can be used to profile vacancy-type defects located near half the projected range ([FRACTION SHAPE="CASE"][NUM]1[/NUM][DEN]2[/DEN][/FRACTION] R[sub p]) in MeV-implanted Si. In this letter, we have determined the ratio of vacancies annihilated to Au atoms trapped (calibration factor "k") for the Au-labeling technique. The calibration experiment consisted of three steps: (1) a 2 MeV Si[sup +] implant into Si(100) followed by annealing at 815 °C to form stable excess vacancy defects; (2) controlled injection of interstitials in the [FRACTION SHAPE="CASE"][NUM]1[/NUM][DEN]2[/DEN][/FRACTION] R[sub p] region of the above implant via 600 keV Si[sup +] ions followed by annealing to dissolve the {311} defects; and (3) Au labeling. The reduction in Au concentration in the near-surface region (0.1-1.6 μm) with increasing interstitial injection provides the most direct evidence so far that Au labeling detects the vacancy-type defects. By correlating this reduction in Au with the known number of interstitials injected, it was determined that k=1.2±0.2 vacancies per trapped Au atom. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The influence of ion mass on transient enhanced diffusion (TED) and defect evolution after ion implantation in Si has been studied by atomistic simulation and compared with experiments. We have analyzed the TED induced by B, P, and As implants with equal range and energy: TED increases with ion mass for equal range implants, and species of different mass but equal energy cause approximately the same amount of TED. Heavier ions produce a larger redistribution of the Si atoms in the crystal, leading to a larger excess of interstitials deeper in the bulk and an excess of vacancies closer to the surface. For high-mass ions more interstitials escape recombination with vacancies, are stored in clusters, and then contribute to TED. TED can be described in terms of an effective “+n” or “plus factor” that increases with the implanted ion mass. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]