MEASUREMENT OF HEIGHT OF MELT LEVEL IN CZ METHOD

PURPOSE:To accurately measure height of melt level without being influenced by waving of melt level by adding compensation based on distance between peaks to a peak position in the vertical direction at the central part of the peaks to obtain height of melt level. CONSTITUTION:Single crystal 4 of silicon, etc., is successively pulled up from melt 2 in a crucible 1 and a fusion ring 5 is produced at a position in contact with melt level at the lower part of the single crystal 4. For example, the fusion ring 5 is observed by an optical means 8 through an observing window 7. An ordinary optical measuring device can be used as the optical means 8 to measure the fusion ring by light or a CCD camera may be used. In the case of measurement by the CCD camera, diameter of the fusion ring can be measured by measuring the diameter of the fusion ring on a measuring line. A value corresponding to the height of melt level can be measured at a peak position in the vertical direction.