Optimization of the shape of high-frequency inductor for the pedestal growth of silicon crystals

K. Surovovs¹ - A. Kravtsov² - J. Virbulis¹

¹ Department of Physics, University of Latvia, 3 Jelgavas str., LV-1004 Riga, Latvia
² KEPP EU, 5 Carnikavas str., LV-1034 Riga, Latvia

Abstract
The present paper is focused on mathematical modelling and experimental development of the pedestal growth of silicon crystals. In the considered crystal growth method, the melt is heated electromagnetically, using a ring-shaped high-frequency inductor. Crystal seeding experiments were challenging and needed the support of numerical modelling for the improvement of thermal conditions. The importance of additional heating of the pedestal side surface was shown. Polycrystalline sample rods have been successfully grown, thus demonstrating the plausibility of the realiztion of the pedestal growth method. However, to increase the crystal diameter, the inductor shape has to be optimized. Due to the system's high sensitivity to the inductor geometry, an automatic optimization algorithm that utilizes the gradient method in the phase space of the inductor parameters has been developed. The ability to grow crystals with diameters up to 90 mm if a side heater is applied was demonstrated using numerical simulations. Tables 2, Figs 10, Refs 20.