Molecular Dynamics Modeling of Stress and Orientation Dependence of Solid Phase Epitaxial Regrowth
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Molecular Dynamics Modeling of Stress and Orientation Dependent Solid Phase Epitaxial Regrowth Haoyu Lai0, Stephen M. Cea0, Harold Kennel0 and Scott T. Dunham0 1 Electrical Engineering, University of Washington, Seattle, Washington, USA. 2 Design and Technology Solutions, Intel Corporation, Hillsboro, Oregon, USA.
ABSTRACT Solid Phase Epitaxial Regrowth (SPER) is of great technological importance in semiconductor device fabrication. A better understanding and accurately modeling of its behavior are vital to the design of fabrication processes and the improvement of the device performance. In this paper, SPER was modeled by Molecular Dynamics (MD) with Tersoff potential. Extensive MD simulations were conducted to study the dependence of SPER rate on growth orientation and uniaxial stress. The results were compared with experimental data. It was concluded that MD with Tersoff potential can qualitively describe the SPER process. For a more quantitatively accurate model, a better interatomic potential are needed. INTRODUCTION Solid Phase Epitaxial Regrowth (SPER), the epitaxial recrystallization of amorphous Si in solid phase, is used extensively in semiconductor device fabrication to repair the crystal damage caused by ion implantation as well as incorporate and activate the implanted dopants. In many cases, it can even be used to obtain solid solution beyond the dopant’s solubility. However, it is well known that this process also generates defects such as stacking faults, dislocation loops and micro twins [1]. These defects can act as scattering centers or electron-hole recombination centers and severely degrade device performance [2, 3]. In addition, dopants diffuse differently in crystalline Si, amorphous Si and at the amorphous/crystal (a/c) interface. As a result, the final dopant profile, which is very critical to nanoscale device structures such as ultra-shallow junctions, can also be altered. Therefore, a better understanding of SPER and accurately modeling of its behavior are vital to the design of fabrication processes and the improvement of the device performance. It has been demonstrated by experiments that the rate of SPER depends on temperature [4], orientation [5], uniaxial stress [6, 7] and pressure [8]. Combinations of these factors may result in many critical phenomena that affect the device performance. For example, the orientation dependence leads to mask edge defect formation [9, 10], augmented by the dependence on local curvature of the a/c interface which may originate from the stress dependence. In this paper, Molecular Dynamics (MD) is used to model and study two of the four important aspects of SPER: orientation and uniaxial stress dependence. MD is a powerful computer simulation tool. With the proper interatomic potential, it can be used to study the dynamics of the SPER in atomistic detail and provide physical insight. It also can be used to extract parameters for higher level modeling.
INTERATOMIC POTENTIAL USED IN MD There are three types of interatomic potentials for MD s
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