Computer Simulation of Decaborane Implantation into Silicon, Annealing and Re-crystallization of Silicon
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Computer Simulation of Decaborane Implantation into Silicon, Annealing and Recrystallization of Silicon Zinetulla Insepov and Isao Yamada Laboratory of Advanced Science &Technology for Industry, Himeji Institute of Technology, 31-2 Kouto, Kamigori, Ako, Hyogo 678-1205 Japan ABSTRACT Molecular Dynamics (MD) and Activation-Relaxation Technique (ART) models of decaborane ion implantation into Si and following rapid thermal annealing (RTA) processes have been developed. The B and Si atomic positions for implantation of accelerated decaborane ions, with total energy 3.5- 15 KeV, into Si substrate were obtained by MD simulation. The main difference between monomer and decaborane ion implantation with the same doses is the formation of a large amorphized area in a subsurface region for the decaborane case. The number of displaced Si atoms shows non-linear energy dependence at low impact energies. At higher energies of the investigated range of the decaborane energy range, however, a linear dependence is observed in accordance with the prediction of the Kinchin-Pease formula. A new method that incorporates Activation-Relaxation Technique (ART) with MD has been developed and used to study recrystallization of Si amorphized in the implantation process. INTRODUCTION Implantation of a decaborane cluster ion, (B10H14)+, has first successfully been realized in experiments by a Kyoto University group, in cooperation with Fujitsu company [1]. Implanted B dopant diffusion in Si has recently attracted much attention because of the anomalously high diffusion rate, the transient enhanced diffusion (TED) effect that is typical for conventional implantation method that uses single ion implantation. This effect has immediately been revealed after the Si samples heavily doped with decaborane ions were rapidly thermally annealed at a temperature of about 800 - 1000 °C for 10s. [2]. A physical model of TED states that every implanted B+ ion creates at least one Si-interstitial (the so called +1 model), and that the highly migrating B interstitials are due to the kick-out mechanism caused by the Si selfinterstitials [3]. Dopant diffusion in Si is a well studied area of semiconductor physics [4-10]. The need for modeling of low energy decaborane implantation has emerged only recently, following experimental confirmation of this process as a potential replacement for low energy single B+ ion implantation. To the authors' knowledge, there has been only one simulation of 1.5 and 4 keV decaborane implantation into a Si substrate with Molecular Dynamics (MD) [11]. Development of new modeling methods of re-crystallization of amorphized Silicon substrate area is an important current topic in fundamental materials science [13-17]. The main deficiency of MD method in studying the kinetics of re-crystallization of amorphous materials is that the simulation time in MD, usually less than 20 ps, is too short compared with the times of crystal ordering that are many orders of magnitude longer. The aim of this paper is to report on the development of new com
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