Viscosity of molten silicon and the factors affecting measurement

Viscosity of molten silicon has been measured to study the behavior, especially around the melting point, in order to supply useful information for the crystal growth of semiconductors. The temperature range was taken as wide as possible from 1891 K down to the supercooled region by using an oscillating viscometer with various materials of crucible to study the effect of the materials. It has been clear that the viscosity of molten silicon showed a good Arrhenian behavior in the entire temperature range including the supercooled region and no abnormal increase around the melting point. The viscosity values were lower than the reported values and the maximum difference reached 50% even in the temperatures sufficiently higher than the melting point. Furthermore, almost no effect on the measurement by the materials of crucible was found. The recommended viscosity is presented by the following equation based on the present results: log η/mPa s = -0.727 + 819/T, E_η = 15.7 kJ mol^-1. The viscosity and the activation energy were considerably lower than those of other metals with high melting points and the reason was considered to be due to the looser structure of the molten silicon originated from diamond-type solid structure.