Boron-Interstitial Cluster Kinetics: Extraction of Binding Energies from Dedicated Experiments
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Boron-Interstitial Cluster Kinetics: Extraction of Binding Energies from Dedicated Experiments Christophe J. Ortiz,1 Peter Pichler,1 Volker H¨aublein,1 Giovanni Mannino,2 Silvia Scalese,2 Vittorio Privitera,2 Sandro Solmi,3 and Wilfried Lerch4 1 Fraunhofer-Institut f¨ ur Integrierte Systeme und Bauelementetechnologie Schottkystrasse 10, 91058 Erlangen, Germany 2 IMM-CNR, Sezione di Catania, Stradale Primosole, 95121 Catania, Italy 3 IMM-CNR, Sezione di Bologna, Via P. Gobetti 101, 40129 Bologna, Italy 4 Mattson Thermal Products GmbH, Daimlerstrasse 10, 89160 Dornstadt, Germany ABSTRACT A description of the transient diffusion and activation of boron during post-implantation annealing steps is one of the most challenging tasks. In industrially relevant situation, it needs to address diffusion at extrinsic concentrations, the agglomeration of self-interstitials, and the formation of boron-interstitial clusters. This article describes the experimental work performed or used to calibrate model parameters as independently as possible. In particular, the experiments used to extract information about the energetics of boron-interstitial clusters are described. INTRODUCTION Since the pioneering work of Pelaz et al. [1] and Caturla et al. [2] it is known that small, selfinterstitial rich boron agglomerates, called boron-interstitial clusters or, shorter, BICs may form during the annealing of boron implants into crystalline silicon. Despite a veritable number of experimental and theoretical investigations, as outlined in a recent review [3], considerable discrepancies exist with respect to the kinetics and energetics of BICs. The reason for such discrepancies is certainly that most experimental determinations were based on set-ups in which the redistribution and activation of the implanted boron atoms are used to extract BIC–specific parameters. While such situations are certainly technology-relevant, they do not allow to separate reliably high-concentration diffusion, formation of self-interstitial clusters, the state after ion implantation, and finally the actual formation of BICs. On the other hand, such a separation is possible in a set-up suggested by Solmi et al. [4]. It is based on a near-surface generation of self-interstitials by the implantation of silicon which induces the formation of BICs in a spatially separated borondoped layer. The work presented here follows this concept and enables a quantitative analysis by the use of independently calibrated models for high-concentration diffusion and the agglomeration of self-interstitials. EXPERIMENTAL CONDITIONS The experiments performed in this study used samples of 1×1 cm2 provided by Philips Innovative Technology Solutions in Leuven, Belgium. They contained an epitaxially deposited structure with a buried boron layer at a depth of 0.48–0.62 µm with a concentration of 1019 cm−3 . In the as-grown state, all of the boron atoms in the layer are assumed to be on substitutional sites. At a depth of 0.9 µm, the structure contained a delta layer lightly doped with bo
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