Cold core shouldering micropulling proparation method of large size sapphire single crystal

Abstract

The invention relates to sapphire single crystal growth method. The feature is that: the temperature of cooling water output is stabilized at 15-35 degree centigrade and during the whole technology process the vacuum pressure is less than 6*0.001Pa. Using tungsten heating body and crucible, tungsten molybdenum separating shield and high temperature component, the sapphire crystal is made in the single crystal furnace. In the crystal seeding process, it includes slowly adjusting the seed crystal to make the bottom above the melt liquid surface 5-20mm, preheating and removing thermal stress; using the classic crystal pulling method technology, after 5-15 times crystal seeding along the cold core departure direction to transferring the crystallizing center to cold core, cooperating rotating controlling and the rotating speed is 2-16 round per minute.

Description

Technical field: [0001] The invention relates to a method for growing a sapphire single crystal, in particular to a method for preparing a large-size sapphire single crystal by cold-heart shoulder micro-pulling. Background technique: [0002] Sapphire (α-Al 2 o 3 ), also known as white gem, is a crystal material whose hardness is second only to diamond. It has high hardness (Mohs hardness 9), high temperature resistance (melting point up to 2050 ℃), strong abrasion resistance and corrosion resistance, stable chemical properties, generally insoluble in water, not subject to acid corrosion, light transmission performance, electrical insulation performance A series of excellent characteristics. Sapphire single crystal can be used in microwave tube media, ultrasonic transmission components, delay lines, waveguide laser cavities and precision instrument bearings, optical components such as balance knife edges, as well as infrared military devices, satellite space technology, w...

AI Technical Summary

Problems solved by technology

In the above method, the single crystal grown by the flame method has a large temperature gradient and high defects and stress values, so it is difficult to mass-produce sapphire products with low cost and high quality; although the pulling method can produce high-quality single crystal crystal material, but because the seed crystal requires a certain speed of rotation during the growth process, the diameter of the single crystal is small, and the crystallographic direction used by the single crystal has a certain angle with the pulling direction of the single crystal, so the utilization rate is very low ; Although the zone melting method can reduce the energy consumption of single crystal growth, it will greatly increase the dislocation density of the single crystal and reduce its use efficiency; The method of using the substrate substrate sapphire was not adopted because the defect density per unit area of ​​sapphire was too high; the common feature of the heat exchange method and the guided temperature gradient method is that it can grow a larger sapphire single crystal, and the crystal quality is very high. The utilization rate of the crucible is very low, making the cost of this method high