Surface Tension Variation of Molten Silicon Measured by the Ring Method

The detailed temperature dependence of the surface tension of molten silicon was measured using an accurate ring method. The surface tension data obtained using a SiC-coated graphite crucible showed an approximately linear temperature dependence from 1,430° C to 1,650° C. Although the temperature dependence of the surface tension of molten silicon in a quartz glass crucible was similar to the above, the maximum value of the surface tension was about 20 dyn/cm smaller than that in the case of the SiC crucible. The temperature coefficient of the surface tension became positive at about 1,425° C and returned to a negative value just above the melring point. These results indicate that surface melt flow near the meniscus of a growing crystal tends to be opposite to the crystal.