| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure a liquid level position of melt and a diameter of a single crystal in pulling of the single crystal in the Czochralski method.SOLUTION: An image of a meniscus for forming a border of the single crystal pulled in the Czochralski method and a raw material melt in a crucible 12 is taken, and a fusion ring emerged in the meniscus is detected based on a brightness distribution of the taken image. Then, an edge line of the fusion ring is simulated to make an approximate curve by approximating to an even function, and the edge line of the fusion ring is corrected by removing a pixel region positioned in a melt side from the approximation curve, in which a deviation from the approximation curve is the number of specified pixels or more. Based on the corrected position of the fusion ring, a liquid level position of the melt is calculated, and based on the calculated liquid level, a height position of the crucible 12 for accommodating the melt is controlled, and an interval between a bottom edge of a cylindrical thermal shield body 16 disposed in an upper side of the crucible 12 and the liquid level is adjusted.SELECTED DRAWING: Figure 4 |
