Epitaxial silicon carbide simulations vs. experiments: etching, growth rates and aluminum/nitrogen doping
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Epitaxial silicon carbide simulations vs. experiments: etching, growth rates and aluminum/nitrogen doping Jérôme Mézière 1, Elisabeth Blanquet 1, Michel Pons 1, Jean-Marc Dedulle 1, Pierre Ferret 2, Léa Di Cioccio 2, Thierry Billon 2 1 LTPCM UMR 5614 of CNRS, INPG/UJF, Domaine Universitaire, BP 75, 38402 Saint Martin d'Hères cedex, France. 2 CEA/DRT/LETI CEA-Grenoble, 38054 Grenoble Cedex 9, France ABSTRACT This paper summarizes recent experimental and simulation results on etching, growth rates and aluminum/nitrogen incorporation in SiC epitaxial layers grown in a horizontal LPCVD hotwall reactor commercialized by the Epigress company. The combined use of modeling and experiments allows to identify and to quantify the main growth phenomena. In this paper, a chemistry model including surface deposition and hydrogen etching is first described. It is found that the contribution of the etching of the susceptor to the SiC growth is not negligible. A simple model is used to describe nitrogen incorporation. INTRODUCTION Compared to silicon, silicon carbide possesses many favorable properties which make it interesting for a multitude of applications, from high temperature to high frequency and high power device. However, SiC device processing is conditioned by the deposition of large area epitaxial thin films with good structural quality and controlled doping level [1]. Huge improvements have been observed in the last several years. They come mainly from extensive experimental effort, from different research groups all over the world. In parallel, macroscopic modeling has been developed to understand the impact of some operating parameters and lead to a new reactor design for enlarging the homogeneous deposition area [2-6]. With a hot-wall CVD reactor, commercially available from the Epigress Company, and implemented in LETI, CEA Grenoble, it has been possible to obtain SiC layers of high quality which fulfill the requirements of device processing [7]. Modeling and simulation in its actual 3D geometry is carried out to provide insights into the process phenomena and finally may bring technological solutions to insure industrial transfer. In this paper we present the chemistry models developed for SiC deposition and hydrogen etching. Development of a model which describes the incorporation of nitrogen in SiC layer is under progress. Simulation results giving the evolution of etching rate, deposition rate and nitrogen doping along the susceptor are compared to experimental results obtained with an etching process on three 2” wafers and an epitaxial growth on five 2” wafers. MODELING Chemical Vapor Deposition of SiC involves a variety of interconnected phenomena that must be described in the process modeling. The commercially available software CFD-ACE+ has been used in all calculations1. First, flow and thermal fields have been obtained from 3D modeling 1
CFD-ACE+, CFD Research Corporation, 215 Wynn Drive, Hunstville, AL 35805 USA, http:/www.cfdrc.com/
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including electromagnetics, radiation and fluid dynami
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