SURFACE-TENSION MEASUREMENT OF MOLTEN SILICON BY THE OSCILLATING DROP METHOD USING ELECTROMAGNETIC-LEVITATION

The surface tension of molten silicon was successfully measured by an oscillating drop method using electromagnetic levitation over a wide temperature range from 1100 to 1500 degrees C including the undercooling condition of Delta T approximate to 300 K. Single crystals of silicon heavily doped with B and Sb (resistivity as low as 1 x 10(-4) Omega . m) were successfully melted and levitated. The surface tension of molten silicon was 783.5 x 10(-3) N/m at the melting point of 1410 degrees C within the measurement accuracy of 3-4%; its temperature coefficient was -0.65 x 10(-3) N/m K. Secondary ion mass spectroscopy (SIMS) analysis showed that O and Sb evaporated during melting, while the B concentration after melting was unchanged. This means that surface tension and its measured temperature dependence correspond to those for a contamination-free silicon melt.