Rotary shoulder technique for growing sapphire crystal by kyropoulos method

Abstract

The invention discloses a rotary shoulder technique for growing sapphire crystal by a kyropoulos method. In the sapphire growth process employing the kyropoulos method, the power is reduced to enter the shoulder stage after seeding of the crystal is finished; the crystal is kept in a rotary state at this stage, and meanwhile, the withdrawal rate of the crystal is kept; the diameter of the crystal is gradually enlarged along with an upward pulling process; rotation of the crystal is stopped when the growth weight achieves 8-10% of inventory; and the crystal enters an equant growth stage in a vertical pulling state. By adopting the rotary shoulder technique disclosed by the invention, vortex rotating along with the crystal is formed by flux on a solid-liquid interface along with rotation of the crystal; and an air bubble gathered on the solid-liquid interface is gradually discharged along with flow of the flux. Therefore, the content of the air bubble can be effectively reduced; the quality and the utilization rate of the crystal are improved; crystal sticking on crucible caused by over-quick crystal growth in one direction and uneven temperature field also can be effectively avoided; molding of the appearance of the crystal is facilitated; subsequent crystal manufacturing procedures are facilitated; the stick cutting rate can be improved; and the product usage is also improved.

Description

technical field [0001] The invention relates to a method for growing large-sized sapphire crystals by a top seed crystal kyropoulos method, in particular to a new rotary shouldering process for kyropoulos growth of sapphire crystals. Background technique [0002] α-Al 2 o 3 Single crystal, also known as sapphire, is a simple coordination oxide crystal. Sapphire single crystal has excellent optical and mechanical properties, stable chemical properties, and is widely used in infrared military devices, satellite space technology, and high-intensity laser window materials; its unique lattice structure and good thermal stability make sapphire Single crystal has become an ideal substrate material for GaN light-emitting diodes. [0003] The melting temperature of sapphire crystal is about 2050°C. The Kyropoulos method is currently the mainstream growth method for sapphire substrate sources, represented by Rubicon in the United States and MonoCrystal in Russia. The Kyropoulos me...

AI Technical Summary

Problems solved by technology

In the traditional process, after the seeding is finished, the seed crystal stops rotating and enters the shouldering stage. During the shouldering stage, the crystal 2 does not rotate and is pulled vertically, which will cause a large number of bubbles to appear in the center of the crystal; these bubbles come from the melting process of raw materials. Part of the gas that is too late to be pumped out by the molecular pump or mechanical pump, these bubbles remain in the melt and move with the eddy current; as the melt circulates, the bubbles will be enriched at the center tip of the lower part of the growing crystal, forming a central bubble zone 3, which will seriously Affects crystal quality and utilization

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