Cryst. Res. Technol. 43, No. 2, 145 – 151 (2008) / DOI 10.1002/crat.200710993 © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Influence of active afterheater on the induction heating process in oxide Czochralski systems M. H. Tavakoli*, F. Samavat, and M. Babaiepour Physics Department, Bu-Ali Sina University, Hamedan, Iran Received 17 July 2007, accepted 26 September 2007 Published online 19 October 2007 Key words computer simulation, Czochralski method, induction heating. PACS 02.60.Cb, 02.70.Dh, 41.20.-q, 81.10.Fq Different shapes and orientations of an active afterheater for oxide Czochralski crystal growth systems are considered and corresponding results of electromagnetic field and volumetric heat generation have been computed using a finite element method (Flex-PDE package). For the calculations, the eddy current in the induction coil (i.e. the self-inductance effect) has been taken into account. The calculation results show the importance of an active afterheater, its shape as well as its geometry and position with respect to the crucible on the heat generation distribution in a CZ growth system. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Today the method of radiofrequency induction heating is widely used in crystal growth technology. This method is applied to generate directly the required thermal power in the metallic parts. In oxide Czochralski (CZ) systems (Figure 1), this induction power is produced by an induction heater coil (copper) that surrounds the metal crucible (usually iridium or platinum). A high frequency electric current (~10 kHz) in this coil induces an eddy current distribution in the metal crucible and afterheater. The final product is the rate of energy dissipation in the crucible and afterheater -Joulean heating (I 2 R) in the form of temporal and spatial volumetric heating. This internal heat generation is partly transferred into the melt and gas via the inner wall and bottom of the crucible and the afterheater wall and top cover, and partly lost to the surroundings via the outer surfaces of insulation. Using an active afterheater in oxide CZ growth is common for controlling the heat transfer mechanisms and temperature field in the setup. Presence of an active afterheater in the CZ furnace affects markedly on the heat generation and complicated thermal field in the system and also represents a challenging problem of numerical modeling [1-4]. The goal of this article is to reveal the role of an active afterheater on the induction heating process and compare the corresponding results of electromagnetic field and heat generation distribution for an oxide Czochralski system using a FEM numerical approach. To do it, different shapes and orientations of an active afterheater with respect to the crucible are considered corresponding to the real growth situations. Our challenge is to extend the fundamental understanding of induction heating process used for crystal growth technology, because this understanding will enable the growers to optimize existing procedures and design of new growth methods. 2 Mathematical model Following assumptions are made in our numerical calculations: (1) The system is axisymmetric. (2) All media are linear, isotropic and stationary. (3) All materials are non-magnetic and have no net charge. (4) The ____________________ * Corresponding author: e-mail: mht@basu.ac.ir