TEMPERATURE-DEPENDENCE OF THE VISCOSITY OF MOLTEN SILICON MEASURED BY THE OSCILLATING CUP METHOD

The viscosity of molten silicon was measured using a oscillating cup made of SiC. In the temperature range, from the solidification point of about 1,415 degrees C to about 1,600 degrees C, the viscosity ranged from 0.7 to 0.9 mPa . s. The activation energy estimated from the data was 0.20 eV. An anomalous increase in the viscosity with decreasing temperature was observed for temperatures lower than about 1,430 degrees C. In this temperature range, an anomalous temperature dependence of the density and surface tension have been observed. Our results thus indicate that the anomalous behavior of different properties occurs simultaneously, reflecting a kind of essential variation in the melt.