Rotating shoulder-expanding stable pulling-up method for large-kilogram sapphire crystals

Abstract

The invention discloses a rotating shoulder-expanding stable pulling-up method for large-kilogram sapphire crystals. The method comprises the steps as follows: heating for material melting to enable the raw materials to be just melted and enable the temperature of the melted material to be close to a melting point; lowering a crystalline style, and preheating a seed crystal mounted below the crystalline style; measuring temperature to adjust and control the temperature of the melted material to a crystal growth temperature; seeding, to be specific, placing the clean seed crystal above liquid level in a standing manner to enable the surface of the seed crystal to melt, rotating the crystalline style, and actuating the seeding process after an artificial cold-core is formed; actuating an automatic shoulder-expanding procedure, lifting the crystalline style at uniform speed, adjusting the power of a heater to lower the temperature gradually, at the same time, keeping the rotation of the crystalline style, stopping rotation when the weight of the crystal reaches 5 kg, enabling the rotating speed of the crystalline style to gradually decrease by stages when the weight of the crystal is 0-5 kg; actuating an automatic growing procedure when the weight of the crystal reaches 10 kg, lifting the crystalline style at uniform speed, adjusting the power of the heater to lower the temperature gradually; finally, separating, cooling, and taking out the crystal, so that the whole crystal growing process is completed. Through the method provided by the invention, the seeding and shoulder-expanding method in the prior art are improved, and the finished product rate as well as the yield are improved.

Description

technical field [0001] The present invention relates to the rotating shoulder expansion stable pulling method (RESPM) of sapphire crystals with a large number of kilograms (greater than 85kg). Background technique [0002] The existing seeding technology uses tungsten crucibles and tungsten metal heaters in pursuit of reasonable costs. Although this thermal field design achieves the purpose of reducing costs, it is easy to cause large and unstable molten soup streamlines and thermal fields. It is not easy to find a stable cooling core in the early stage of crystal growth and shoulder expansion, and it is easily affected by the thermal field and the flow line of the melt, which makes it difficult to control the growth rate, and it is impossible to find a reasonable growth rate, which may easily cause excessive internal stress or crystal growth. The solid-liquid interface is reversed, and a stable crystal growth environment cannot be obtained, resulting in crystal cracking, or...

AI Technical Summary

Problems solved by technology

[0002] The existing seeding technology uses tungsten crucible and tungsten metal heater in pursuit of reasonable cost. Although this kind of thermal field design achieves the purpose of reducing costs, it is easy to cause large and unstable molten soup streamlines and thermal field. It is not easy to find a stable cooling core in the initial stage of crystal growth and shoulder expansion, and it is easily affected by the thermal field and the flow line of the melt, which makes it difficult to control the growth rate, and it is impossible to find a reasonable growth rate, which may easily cause excessive internal stress or crystal growth. The solid-liquid interface is reversed, and a stable crystal growth environment cannot be obtained, resulting in crystal cracking, or serious small-angle grain boundaries and air bubbles, resulting in low crystal yield and yield

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