Journal of Crystal Growth 266 (2004) 48–53 Effects of temperature coefficient of surface tension on oxygen transport in a small silicon Cz furnace You-Rong Li a,b , Nobuyuki Imaishi b, *, Yasunobu Akiyama b , Lan Peng a,b , Shuang-Ying Wu a , Takao Tsukada c a College of Power Engineering, Chongqing University, Chongqing 400044, China b Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen, Kasuga Fukuoka 816-8580, Japan c Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan Abstract In order to understand the effects of temperature coefficient of surface tension (g T ) on oxygen transport as well as on the heater power and the melt/crystal interface shape in a small silicon Czochralski furnace, a set of global numerical simulations is conducted using the finite-element method for a wide range of g T between 0 and 0.35  10 3 N/m K. The results for cases without rotations of crystal and crucible indicate that the larger Marangoni effect enhances a toroidal roll cell in the crucible and reduces the heater power and oxygen concentration in the crystal but makes the melt/crystal interface more convex toward melt. When the crystal and the crucible are rotating in counter directions, an upwelling flow near the axis from the bottom of the crucible takes important role in determining the radial distributions of oxygen concentration. g T gives significant effects on the flow pattern, oxygen concentration, heater power and interface shape. r 2004 Elsevier B.V. All rights reserved. PACS: 81.10.Aj; 81.10.Fq; 47.15.x; 02.70.Dh Keywords: A1. Computer simulation; A1. Mass transfer; A2. Czochralski method; B1. Semiconducting silicon 1. Introduction In the Czochralski (Cz) silicon crystal growth technique, mass transfer rate of oxygen in the melt and that of SiO in the gas phase is strongly influenced by the melt flow driven by the various forces, such as the buoyancy force, the centrifugal and the Coriolis forces due to the crystal and crucible rotations, shear stress due to the gas flow along the melt surface and the thermocapillary force due to the temperature dependence of the surface tension at the melt surface. In recent years, many numerical analyses [1–11] have been con- ducted on the melt flow and the oxygen transport in the silicon melt. In these works, the Marangoni effect has not been taken into account. However, the experimental results obtained by Kawanishi et al. [12], Kanda et al. [13] and Nakanishi et al. [14] suggest that the melt surface flow, driven by the Marangoni effect, plays a very important role in the radial nonuniformity of oxygen concentra- tion in crystal. In the papers of Sabhapathy et al. [15] and Chung et al. [16], the contribution of Marangoni effect to the flow pattern is included ARTICLE IN PRESS *Corresponding author. Tel.: +81-92-583-7793; fax: +81- 92-583-7796. E-mail address: imaishi@cm.kyushu-u.ac.jp (N. Imaishi). 0022-0248/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jcrysgro.2004.02.085