SAPPHIRE SINGLE CRYSTAL AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a high quality sapphire single crystal less in pits or particles by suppressing capture of air bubbles and contamination of a crucible material during growth.SOLUTION: The sapphire single crystal is grown by a vertical temperature gradient freezing method or a vertical Bridgman method using a crucible 6 made of tungsten. The method for manufacturing the sapphire single crystal comprises: the growth step of increasing a temperature in a furnace 1 to a constant temperature in a range of 2040-2060°C, adjusting a temperature gradient in a growth axis direction in a region of 2 cm in a vertical direction across a solid-liquid interface to be 5.0-6.0°C/cm and crystallizing a raw material melt 9 while controlling a growth rate in a range of 0.8-1.3 mm/hr; and the cooling step of lowering the temperature in the furnace 1 to a constant temperature in a range of 1900-2000°C, adjusting the temperature gradient in the growth axis direction of the sapphire single crystal at 1.9°C/cm or less toward the upper surface of the sapphire single crystal from the bottom of the crucible 6 and lowering the temperature in the furnace 1 at 10-30°C/hr to cool the sapphire single crystal to a room temperature.SELECTED DRAWING: Figure 1