Device for growing profiled sapphire monocrystals

FIELD: growing monocrystals of refractory oxides from melts by oriented crystallization; production of sapphire monocrystals corresponding to opto-electronics requirements.

SUBSTANCE: proposed device has vacuum chamber with crucible and molding unit, tungsten heater, shields, rod with seed holder which is provided with crystal raising mechanism mounted outside the chamber, melt make-up system made in form of bin with tube and unit for control of heating and rate of raising the crystal. Device is additionally provided with annealing vacuum chamber mounted above chamber with crucible and molding unit coaxially relative to it and system for synchronization of mass of crystal being grown and consumption of make-up material; annealing vacuum chamber is provided with self-contained heater whose height is equal to or exceeds maximum size of length of crystal obtained; diameter of annealing chamber ranges from 0.6 to 0.9 of diameter of lower chamber; mounted in between chambers is partition with holes for rod with seed holder, crystal being grown and make-up; molding unit is made in form of parallelepiped with parallel through vertical slots which is mounted in crucible at clearance and is secured on crucible walls; height of parallelepiped is equal to 20-30% of crucible height; width of slots is 0.2-0.3 mm at distance between them of 0.2-0.5 mm; in horizontal plane ends of slots are blind. Proposed device makes it possible to eliminate voids lesser than 50 mcm in diameter at obtaining the crystals whose transversal size is lesser than 100 mm at crystallographic orientation of <1010> or <1120>. Power requirements are reduced by 4-6 times. Monocrystals grown with the aid of this device have low internal stresses which is important for further mechanical treatment of crystals.

EFFECT: reduced power requirements; low internal stresses of crystals.

7 cl, 2 dwg

 

The invention relates to the field of growing single crystals of refractory oxides from the melt by the method of directional solidification and can be used to obtain single crystals of sapphire, the relevant requirements of optoelectronics.

A device for growing single crystals based on complex oxides which are sealed chamber in which is mounted a vertically movable and rotatable rod with attached seed, water-cooled coil connected to a source of induction heating, water-cooled bottom, made in the form of a spiral, the crucible, made with a hole at the bottom and fixed inside the inductor in a stationary position, the boot device in the form of a sealed hopper feeder with mixture and feeding tube. The internal volume of the crucible filled with the melt, from which the growing crystal and the melt in the growth process is fed into the crucible through the bottom hole of the additional volume formed by the gap between the crucible and the coil. This device is intended primarily for growing alyumoittrievy garnets and is not intended for growing single crystals of sapphire (SU 904347 A1, 30.04.1993).

Closest to the position of the volume and shape of the grown single crystal, the technical nature of solutions and dostigao the second result is a device for growing single crystals of sapphire, containing installed in a vacuum chamber screens, heater, structurally with fixed therein by the seed crystal, the crucible with the lid and the shaper, the speed regulation system of lifting the seed crystal and the power of the heater in which the camera cover fortified bunker, made in the form of a cylinder with a cone-shaped upper and lower parts, the lower part contains the shut-off valve in the form of a truncated cone, the upper part of the hopper has a bellows, which is connected with the shut-off valve with stem, provided with a mechanism to automatically move the lower part of the hopper tightly inserted into the tube, is lowered into the crucible through the hole in the lid of the crucible. The device allows the use of powdered aluminum oxide and provides obtaining single crystals weighing 12 kg with characteristics to meet the requirements of optoelectronics, and yield not lower than 50% (RU 2232832 C1, 20.07.2004).

However, obtaining crystals of great length, and with the crystallographic orientation of <1010> or <1102> disadvantages are the presence of voids with a diameter of less than 50 microns and high energy costs, significantly affecting the cost of production.

The technical result of the invention is to eliminate the hidden cavities of a diameter less than 50 microns in obtaining crystals with p the pepper up to 100 mm and crystallographic orientation of < 1010> or <1102> while reducing energy costs 4-6 times. In addition, the device allows to obtain single crystals with low residual value of the internal stress, which is important for further mechanical processing of the crystals.

This technical result is achieved in that the device for growing shaped single crystals of sapphire, containing a vacuum chamber with a crucible and a shaper, tungsten heater, screens, stem with structuralism equipped with a lifting mechanism of crystal installed outside the chamber, the feed control of the melt in the form of a hopper with a tube and control systems heating and lifting speed of the crystal, according to the invention, further comprises a vacuum chamber annealing installed over the camera with the crucible and the shaper coaxially with it, and the synchronization system of the mass of the grown crystal and the flow of feed material Luggage annealing has a heater, the height of which is equal to or exceeds the maximum the length dimension of the obtained crystal, the diameter of the camera annealing is 0.6 to 0.9 from the diameter of the bottom of the camera, the cameras are installed partition with holes for rod with structuralism grown crystal and recharge, shaper, made in the form of a parallelepiped parallel with quotname height slots, set in the crucible with a gap and fixed to the walls of the crucible, the height of the parallelepiped is 20-30% of the height of the crucible, the width of the slits is 0.2-0.3 mm, and a distance between 0.2-0.5 mm, the ends of the slots in the horizontal plane is made deaf.

Given the ratio of the diameters of the lower and upper chambers aimed at creating a thermal field, lowering the residual values of internal stresses in the crystal.

A given ratio of the height of the parallelepiped and crucible, as well as the widths of the slits and the distance between them provide the crystallization rate, which minimizes energy consumption and preventing the formation of hidden voids.

In addition, the synchronization system contains sensors differential weighting of the crystal and the flow of feed material, the rod is equipped with a mechanism for axial rotation, a partition between the chambers is made of tungsten or molybdenum sheet, the partition between the chambers are made with adjustable holes, the shaper is made of tungsten or molybdenum, camera and part of the stem, outside cameras, equipped with a water quench system.

The device, called the "Profile +", and the fragment shown in figure 1 and 2.

The device shown in figure 1, includes a vacuum chamber (1), which coaxially e is installed in the upper chamber (2), having a diameter of 0.6 to 0.9 of the diameter of the lower chamber. Chambers separated by a partition wall (9), with holes for rod with structuralism (7) and as-grown crystals, and also for receiving feed material from the feed (8) in the crucible (3) shaper (4). The rod is equipped with a lifting mechanism and axial rotation (not shown). Mainly, the partition between the chambers is made of tungsten or molybdenum sheet, the partition between the chambers are made with adjustable holes.

In the lower chamber with the crucible has a heater (5)in the upper chamber used for annealing of single crystals, installed heater (6), the height of which is equal to or greater than the length of the grown crystal. The lower chamber is equipped with a door, the upper chamber - an observation window (not shown). The synchronization system of the mass of the crystal and the flow of feed material (10) includes sensors differential weighing (11)mounted respectively on the rod (7) and the system of feeding (8).

The shaper (4)representing parallelepiped, mainly of tungsten, with parallel pass-through height slots, installed in the crucible (3) with a gap and fixed to the walls of the crucible. The height of the parallelepiped is 20-30% of the height of the crucible, the width of the slits is 0.2-0.3 mm, distance IU who do them, 0.2-0.5 mm, the ends of the slots in the horizontal plane is made deaf. The cameras have shields (12). Chilled water generating systems, power control of the heaters and the lifting speed of the crystal is not shown.

Figure 2 shows the shaper.

The operation of the device

The crucible (3) fill in the starting mixture in the form of crushed pieces of sapphire or granules of aluminum oxide, establish and fix the shaper (4) and through the door at the bottom of the camera or through the adjustable opening in the septum between the cameras placed in the lower chamber (1) coaxial heater (5). Insert and center in structurale mounted on the rod (7), the seed crystal. Camera (1) and (2) is pressurized and vacuum up (1-5)×10-5mm RT. Art. Feeding power to the lower heater, heat the crucible to the melt temperature of 2100°and maintain the melt prior to its homogenization in 2-3 hours. Then reduce the temperature to 2050°and lower the seed crystal to the former, where the contact of the seed crystal with the melt penetrating through the slots. After exposure for 1-3 minutes the seed crystal lift with speed, due to the shape and size of the grown single crystal. After establishing temperature equilibrium, when the seed crystal is not applauses and on the surface of the melt, the crystal does not grow (approximately 20-30 minutes from the start of the ascent), the temperature decrease for a given program and synchronize the weight of the growing crystal and the supply of feed material in the form of granules.

Execution shaper (4) with a specific configuration and a specific location and size of the slots provides the best crystallization front, resulting uniformity of location of the centers of crystallization (sources of growth steps) and the absence of plastic deformation, causing crystal defects. The size and location of the slots for receiving one of the traditional use in optoelectronics sapphire crystal on a side cross-section less than 100 mm and crystallographic orientation of <1010> or <1102> determined by experiment.

After reaching the growing crystal bottom area of the heater (6) it serves power, providing the temperature of the crystal is approximately 1200°gradually raising it up to 1800°C. When the crystal reaches the specified length, the power flow to the lower heater (5) stop. The opportunity provided by the device, significantly (4-6 times) to reduce energy consumption. Due to the constructive design of the upper chamber of the grown crystal is uniform temperature field with the required temperature. After cooling of the crystal in the 1800°is within 2-3 hours power heater (6) reduce to, providing cooling of the crystal to room temperature at 50°S/h

The result is a single crystal containing no bubbles with diameter less than 50 microns. The presence of hidden voids that are not visible to the naked eye, the technology is usually a difficult task, and this defect significantly limits the scope of single crystals of sapphire. Thus, the essential characteristics of this invention provides for the achievement of the technical result consists in the elimination of hidden voids with a diameter of less than 50 microns in obtaining crystals with cross-sectional dimension of less than 100 mm and crystallographic orientation of <1010> or <1102> while reducing energy costs 4-6 times and reducing the size of the residual internal stress.

1. Device for growing shaped single crystals of sapphire, containing a vacuum chamber with a crucible and a shaper, tungsten heater, screens, stem with structuralism equipped with a lifting mechanism of crystal installed outside the chamber, the feed control of the melt in the form of a hopper with a tube and system heating control and the speed of ascent of the crystal, characterized in that it further comprises a vacuum chamber annealing installed over the camera with the crucible and the shaper coaxially with it, and with the system synchronization mass of the grown crystal and the flow of feed material, the vacuum chamber of the annealing has a heater, the height of which is equal to or exceeds the maximum length of crystal, the diameter of the camera annealing is 0.6 to 0.9 from the diameter of the bottom of the camera, the cameras are installed partition with holes for rod with structuralism grown crystal and recharge, shaper, made in the form of a parallelepiped with parallel pass-through height slots, installed in a crucible with a gap and fixed to the walls of the crucible, the height of the parallelepiped is 20-30% of the height of the crucible, the width of the slits is 0.2-0.3 mm, and a distance between 0.2-0.5 mm, the ends of the slots in the horizontal plane made deaf.

2. Device for growing shaped single crystals of sapphire according to claim 1, characterized in that the synchronization system contains sensors differential weighting of the crystal and the recharge material.

3. Device for growing shaped single crystals of sapphire according to claim 1, characterized in that the rod is further provided with a mechanism for axial rotation.

4. Device for growing shaped single crystals of sapphire according to claim 1, characterized in that the partition between the chambers is made of tungsten or molybdenum sheet.

5. Device for growing shaped single crystals of sapphire on the .1, characterized in that the partition between the chambers are made with adjustable holes.

6. Device for growing shaped single crystals of sapphire according to claim 1, wherein the shaper is made of tungsten or molybdenum.

7. Device for growing shaped single crystals of sapphire 1, wherein the camera and the portion of the rod outside the chambers, equipped with a water quench system.



 

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