CN215828910U - Connecting component of VGF crucible in inverted suction type compound semiconductor crystal synthesis system - Google Patents

Abstract

The utility model discloses a connecting component of a VGF crucible in a back suction type compound semiconductor crystal synthesis system, which comprises a switching fixture for connecting the VGF crucible and an upper furnace body, wherein a back suction pipe is arranged below the VGF crucible, and the connecting component is characterized in that: the switching fixture is connected with an upper furnace cover of the upper furnace body, a clamping ring and a cooling column which are used for forming a crucible clamping groove and a balance gas pipe which upwards penetrates through the upper furnace cover are arranged on the switching fixture, and the top of the VGF crucible is limited in the crucible clamping groove. The utility model has the beneficial effects that: through the design of the switching fixture, the sealing connection between the furnace cover and the VGF crucible is realized, and meanwhile, the seed crystal rod can be introduced into the VGF crucible, so that the switching fixture is a key component for the combined crystal growth of the melt, the LEC and the VGF, and can be repeatedly used.

Description

Connecting component of VGF crucible in inverted suction type compound semiconductor crystal synthesis system

Technical Field

The utility model relates to a connecting component of a VGF crucible in a back-suction type compound semiconductor crystal synthesis system, which is particularly suitable for compound semiconductors with volatile elements, such as indium phosphide, gallium phosphide and other materials.

Background

Compound semiconductor materials such as indium phosphide and gallium phosphide. The method is widely applied to many high and new technical fields such as optical fiber communication, microwave and millimeter wave devices, solar cells and the like, and is widely applied to military and civil fields such as aerospace, network communication, radar and the like.

The synthesis method of the compound semiconductor mainly comprises the following steps: direct synthesis, diffusion synthesis, injection synthesis, and the like. For materials with high saturated vapor pressure such as indium phosphide and gallium phosphide, diffusion synthesis and injection synthesis are generally required. The injection synthesis can greatly shorten the synthesis time, avoid the introduction of impurities and improve the material purity. And the crystal is directly prepared after injection synthesis, so that the preparation time of the crystal can be reduced, the preparation steps can be reduced, and the physical quality of the crystal is greatly improved.

The most commonly used methods for growing semiconductor crystals are: liquid Encapsulated Czochralski (LEC), Vapor Pressure controlled Czochralski (VCZ), Hot screen Czochralski (HWC), and full Liquid Encapsulated Czochralski (FEC); the Bridgman technique is divided into: vertical Bridgman (VB), Horizontal Bridgman (HB), Vertical Gradient Freezing (VGF), and Horizontal Gradient Freezing (HGF), among others.

Conventional VGF crucibles are not sealed to the furnace body. The raw material is welded and sealed by a quartz cap after being put into a traditional VGF crucible, or the VGF crucible is opened and then crystal growth is carried out by seed crystals put into the VGF crucible, and the function of crystal growth after suck-back is not provided.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a connecting assembly of a VGF crucible in a back suction type compound semiconductor crystal synthesis system, wherein the connection of the VGF crucible and an upper furnace body is realized by designing a switching fixture, and the back suction is realized by controlling the pressure in the upper furnace body through a balance gas pipe.

In order to solve the technical problems, the utility model adopts the technical scheme that: a connecting component of a VGF crucible in a back suction type compound semiconductor crystal synthesis system comprises a switching fixture for connecting the VGF crucible and an upper furnace body, wherein a back suction pipe is arranged below the VGF crucible, and the connecting component is characterized in that: the switching fixture is connected with an upper furnace cover of the upper furnace body, a clamping ring and a cooling column which are used for forming a crucible clamping groove and a balance gas pipe which upwards penetrates through the upper furnace cover are arranged on the switching fixture, and the top of the VGF crucible is limited in the crucible clamping groove.

Furthermore, a first sealing ring is arranged between the switching fixture and the upper furnace cover, and a second sealing ring is arranged between the VGF crucible and the crucible clamping groove.

Further, the balance air pipe is connected with the differential pressure pipe, and a differential pressure meter is arranged on the differential pressure pipe.

Furthermore, a transfer hole for connecting a thermocouple is formed in the transfer fixture.

Furthermore, an extension pipe is arranged at the top of the suck-back pipe, the extension pipe is matched with the inner wall of the VGF crucible to form a storage tank for containing the boron oxide II, and the volume of the storage tank is larger than that of the molten boron oxide II.

Further, a VGF crucible supporting and heating system is provided outside the VGF crucible, and the heating system includes a first heater, a second heater, a third heater, a fourth heater and a fifth heater for heating the VGF crucible, and a heater for heating the suck-back pipe.

The utility model has the beneficial effects that: the switching fixture is designed to realize the sealing connection of the furnace cover and the VGF crucible, and meanwhile, the seed crystal rod can be introduced into the VGF crucible, so that the switching fixture is a key component for the combined crystal growth of the melt, LEC and VGF, and can be repeatedly used; the cooling column is used for realizing water cooling, the end face of the VGF crucible is sealed by the clamping ring and the rubber ring, and the cooling column and the retaining ring structure of the VGF crucible are used for blocking air flow, so that the temperature near the rubber ring is further reduced; the VGF crucible is designed, the synthesized first melt is sucked through the suck-back pipe, the storage tank arranged inside the VGF crucible is used for storing boron oxide required by growth of VGF and LEC, the boron oxide at the position can be fully distributed on the inner wall of the VGF crucible along with the rising of the melt, and the integral crystal separation crucible in the later period is convenient.

The present invention will be described in detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic view of the present invention in combination with a downdraft compound semiconductor crystal synthesis system;

FIG. 2 is a schematic view of the main furnace structure;

FIG. 3 is a schematic view showing the assembly of the adapting fixture with the upper furnace cover and the VGF crucible;

figure 4 is a front view of the adapting fixture;

FIG. 5 is a rear view of the adapting jig;

FIG. 6 is a cross-sectional view of the adaptor fixture;

FIG. 7 is a schematic diagram of an injection synthesis system;

FIG. 8 is a schematic view of charging.

In the drawings: 1: a main furnace body; 1-1 main furnace body opening; 2: an upper furnace body; 2-1: putting a furnace cover; 3: a base; 4: a main upright post; 5: an upper furnace body supporting table; 5-1: cleaning holes of the upper furnace body; 5-2: an upper furnace body supporting table column; 6: a main furnace body support table; 6-1: a main furnace body cleaning hole; 6-2: a main furnace body supporting table column; 7: a seed rod driving device loading table; 8: a seed rod driving device; 9, a seed rod; 10: an upper observation window; 11: switching the fixture; 11-1: balancing the air pipe; 11-2: a first seal ring; 11-3: a second seal ring; 11-4: a snap ring; 11-5: a screw hole; 11-6: switching the hole; 11-7: a central bore; 11-8: a sealing groove; 11-9: an observation hole; 11-10: a crucible clamping groove; 11-11: cooling the column; 12: a first compound drive motor; 13: a second composite drive motor; 14: a lower observation window; 15: synthesizing a rotating rod; 16: a synthetic injection system; 16-1: injecting the synthetic heater; 16-2: a loader; 16-3: injecting into a synthesis tube; 17: synthesizing a crucible; 18: supporting a crucible; 19: a main heater; 19-1: an auxiliary heater; 20: melt I; 21: a first heat preservation sleeve; 22: a crucible rod; 23: driving a crucible rod; 24: the crucible rod drives the loading platform; 25: an inflation tube; 26: a vacuum tube; 27: a crucible rod thermocouple; 28: an upper insulating layer shell; 29: a VGF crucible; 29-1: pouring the straw; 29-2: an extension pipe; 29-3: a storage tank; 29-4: a VGF crucible support; 29-5: a VGF crucible baffle ring; 30: an upper heat-insulating layer; 31: a first heater; 32: a second heater; 33: a third heater; 34: a fourth heater; 35: fifth heating device; 36: a suck-back tube heater; 37: a heat-insulating layer of the inverted suction pipe; 38: a first thermocouple; 39: a second thermocouple; 40: a third thermocouple; 41 a fourth thermocouple; 42: a seed rod thermocouple; 43: seed crystal clamping; 44: seed crystal; 45: a second melt; 46: a crystal; 47: boron oxide I; 47-1: boron oxide II; 48: pure indium; 49: fastening screws; 50: red phosphorus; 51: a differential pressure gauge; 52: a differential pressure tube.

Detailed Description

Referring to the attached figures 1, 3-6, the utility model provides a connecting component of a VGF crucible in a back-suction type compound semiconductor crystal synthesis system. Comprises a switching fixture 11 for connecting a VGF crucible 29 and an upper furnace body 2, and a reverse suction pipe 29-1 is arranged below the VGF crucible 29.

The adapter fixture 11 is connected with the inner side of an upper furnace cover 2-1 in the upper furnace body 2. The VGF crucible 29 is set in the upper furnace body 2 by the transfer jig 11. Specifically, screw holes 11-5 are formed in the adapter jig 11, and fastening screws 49 penetrate through the screw holes 11-5 to fix the adapter jig 11 to the upper furnace cover 2-1. A sealing groove is arranged on the contact surface of the upper furnace cover 2-1 and the switching fixture 11, and a first sealing ring 11-2 is arranged in the sealing groove. The fastening screw 49 is connected with its nut facing inwards and the first sealing ring 11-2 is used to prevent air leakage along the gap between the two contact surfaces.

The upper part of the switching fixture 11 is connected with a balance gas pipe 11-1, and the balance gas pipe 11-1 passes through the upper furnace cover 2-1 upwards for adjusting the pressure in the VGF crucible 29. The upper furnace cover 2-1 is also provided with a differential pressure pipe 52, and the differential pressure pipe 52 is connected with the balance air pipe 11-1. A differential pressure gauge 51 is mounted on the differential pressure pipe 52 for measuring a pressure difference between the inside of the VGF crucible 29 and the inside of the furnace body.

The adapter fixture 11 is provided with a snap ring 11-4 and a cooling column 11-11, and an annular gap between the snap ring 11-4 and the cooling column 11-11 forms a crucible clamping groove 11-10. The inner side surface of the snap ring 11-4 is provided with a seal groove 11-8 for placing a second seal ring 11-3. The top of the VGF crucible 29 is arranged in the crucible clamping groove 11-10, and the clamping ring 11-4 and the VGF crucible 29 are sealed through the second sealing ring 11-3. When the VGF crucible 29 is filled with boron oxide II47-1, the thickness of boron oxide II47-1 is greater than 2.5cm for establishing a sufficiently high temperature gradient and reducing the temperature above boron oxide II 47-1. The distance between the surface of the boron oxide II47-1 and the lower ends of the snap ring 11-4 and the cooling column 11-11 is more than 15 cm. Meanwhile, the cooling column 11-11 is connected with an external water circulation device to realize that water cooling is arranged inside the snap ring 11-4 and the whole adapter clamp 11 so as to reduce the temperature of the second sealing ring 11-3 and improve the temperature gradient in the boron oxide II 47-1. The seed rod thermocouple 42 is horizontally arranged in the clamping ring 11-4 and is used for detecting the atmosphere temperature of the rubber ring near the clamping ring 11-4. The lower end of the cooling column 11-11 is inserted into the VGF crucible 29 by a distance greater than the distance from the upper end of the VGF crucible 29-5 to the VGF crucible 29.

The adapting fixture 11 is provided with 4 adapting holes 11-6 for connecting thermocouples in the upper insulating layer 30. The seed crystal hole of the upper furnace cover 2-1 and the central hole 11-7 of the switching fixture 11 are concentric holes and are used for penetrating through the seed crystal rod 9. The observation hole of the upper furnace cover 2-1 and the observation hole 11-9 of the adapter fixture 11 are concentric holes and are used for penetrating through the upper observation window 10. The upper observation window 10 is connected with the upper furnace cover 2-1 in a sealing way.

A VGF crucible support 29-4 is provided outside the VGF crucible 29. The outer side of the VGF crucible support 29-4 is provided with a heating system, and the heating system comprises a first heater 31, a second heater 32, a third heater 33, a fourth heater 34, a fifth heater 35 and a heater 36. The VGF crucible 29 is heated by a first heater 31, a second heater 32, a third heater 33, a fourth heater 34 and a fifth heater 35 outside the VGF crucible support 29-4; the pipette 29-1 is heated by a heater 36. The outer layers of the first heater 31, the second heater 32, the third heater 33, the fourth heater 34 and the fifth heater 35 are provided with an upper heat-insulating layer 30, and the outer side of the upper heat-insulating layer 30 is provided with an upper heat-insulating layer shell 28. A suck-back tube insulating layer 37 is provided around the suck-back tube heater 36. The VGF crucible 29 is heated by the first heater 31, the second heater 32, the third heater 33, and the fourth heater 34 inside the upper insulating layer 30. A first thermocouple 38, a second thermocouple 39, a third thermocouple 40 and a fourth thermocouple 41 are sequentially arranged near the first heater 31, the second heater 32, the third heater 33 and the fourth heater 34; a seed rod thermocouple 42 is arranged in the seed rod 9. The seed rod 9 can enter the VGF crucible 29 through the upper furnace cover 2-1 and the center hole 11-7 of the adapter fixture 11.

Referring to fig. 1 and 2, the upper furnace body 2 is disposed at a main furnace port 1-1 on the main furnace body 1. The upper furnace cover 2-1, the upper furnace body 2, the main furnace body 1 and the base 3 form a sealed furnace chamber. A synthesis system of the compound semiconductor crystal of the inverted suction type is composed of a main furnace body 1, a synthesis crucible 17 positioned in the main furnace body 1, an upper furnace body 2, a VGF crucible 29 positioned in the upper furnace body 2, a seed rod 9 and a synthesis injection system 16.

The main furnace body 1 and the upper furnace body 2 are both arranged on a frame, and the frame comprises a base 3, a main upright post 4, an upper furnace body supporting platform 5 and a main furnace body supporting platform 6. The upper furnace body supporting platform 5 is provided with an upper furnace body cleaning hole 5-1 and an upper furnace body supporting platform column 5-2. The main furnace body support table 6 is provided with a main furnace body cleaning hole 6-1 and a main furnace body support table column 6-2.

The seed rod 9 is moved up and down by the seed rod driving device 8. The seed rod driving device 8 is assembled on a seed rod driving loading platform 7 connected with the upper furnace cover 2-1 to drive the seed rod 9 to move up and down. The seed rod driving device 8 comprises a rotating assembly and a lifting assembly. The rotating assembly comprises a rotating motor and an intermediate plate connected with a rotating shaft of the rotating motor; the lifting component is fixed on the middle plate and comprises an electric push rod, and the tail end of the electric push rod is connected with the seed rod 9. The lifting assembly can also comprise an electric push rod, the tail end of the electric push rod is connected with the middle plate, and the rotating assembly comprises a rotating motor fixed on the middle plate and a seed rod 9 connected with a rotating shaft of the rotating motor.

The main furnace body 1 is fixed on a base 3. A crucible support 18 is provided in the main furnace body 1, and a synthesis crucible 17 is provided inside the crucible support 18. The main furnace body 1 is also provided with an upper observation window 10. The base 3 is provided with an inflation tube 25 and a vacuum tube 26.

A crucible support driving device for driving the crucible support 18 to rotate and move up and down is provided below the main furnace body 1. The crucible support driving means includes a crucible rod 22 and a crucible rod drive 23. The crucible rod 22 passes through the susceptor 3 upward into the interior of the main furnace body 1 and is connected to the crucible support 18. The crucible rod drive 23 is mounted on the crucible rod drive loading table 24 for up-and-down movement. A crucible rod thermocouple 27 is also provided on the crucible rod 22. The crucible rod driver 23 comprises an electric push rod fixed on the crucible rod driving loading platform 24, a connecting plate connected with the electric push rod, and a rotating motor fixed on the connecting plate, wherein a rotating shaft of the rotating motor is connected with the crucible rod 22.

A heating system is provided outside the crucible support 18. The heating system includes a main heater 19 and an auxiliary heater 19-1. The crucible support 18 and the composite crucible 17 are heated by a main heater 19 at the periphery of the crucible support 18 and an auxiliary heater 19-1 located below the main heater 19. Further, a first heat-retaining jacket 21 for retaining heat of the heating system is provided outside the main heater 19.

Referring to FIG. 7, the synthetic injection system 16 includes an injection synthetic heater 16-1, a loader 16-2, and an injection synthetic tube 16-3. The upper part of the main furnace body 1 is provided with a first synthetic driving motor 12 and a second synthetic driving motor 13, and the first synthetic driving motor 12 and the second synthetic driving motor 13 are both connected with a corresponding synthetic injection system 16 through a synthetic rotating rod 15 and drive the synthetic injection system 16 to lift so that the synthetic injection pipe 16-3 is inserted into the synthetic crucible 17. The synthetic injection system 16 is driven to lift up and down between the synthetic driving motor and the synthetic rotating rod 15 through a screw rod nut structure or a gear rack structure.

The lower end of the inverted straw 29-1 is located above the bottom of the synthesis crucible 17. The synthesis injection system 16 is located in the main furnace 1 and the seed crystal 44 in the seed rod 9 is located in the VGF crucible 29. The synthesis crucible 17 is filled with metal raw materials and boron oxide I47, the VGF crucible 29 is filled with boron oxide II47-1, and the synthesis injection system 16 is filled with non-metal raw materials.

The system of the present invention will be described in detail below by taking the preparation of indium phosphide as an example. In this embodiment, the synthesis crucible 17 contains pure indium 48 and the loader 16-2 of the synthesis injection system 16 contains red phosphorus 50.

1. Assembly of the System

The upper furnace body 2 is connected with the upper furnace cover 2-1 and moves to the upper furnace body supporting platform 5, and the main furnace body 1 moves to the main furnace body supporting platform 6.

The insulating jacket I21, the main heater 19 and the auxiliary heater 19-1 are then assembled to the base 3, respectively. The synthesis crucible 17 is then fitted onto the crucible support 18, and the crucible support 18 is fitted onto the crucible rod 22. Boron oxide I47 and pure indium 48 and a dopant were placed inside the synthesis crucible 17.

While 2 synthetic injection systems 16 are fitted to the synthetic turning rods 15. The first and second compound drive motors 12 and 13 raise the 2 compound injection systems 16 to the uppermost position. The synthesis crucible 17 is brought to the lowermost position. Then, by this, the main furnace body 1 is placed on the susceptor 3.

Then the upper furnace body 2 is placed on the main furnace body support platform 6 through the upper furnace body driving device 4-1, then the upper furnace body 2 and the upper furnace cover 2-1 are opened, and then the upper furnace cover 2-1 is lifted above the upper furnace body support platform 5.

Boron oxide II47-1 was placed in storage tank 29-3. Then, the inner side surface of a snap ring 11-4 on the adapter fixture 11 is connected and sealed with the VGF crucible 29 through a second sealing ring 11-3, and the sealing condition is tested through vacuumizing by a reverse suction pipe 29-1.

After the above process is completed, the first heater 31, the second heater 32, the third heater 33, the fourth heater 34, and the fifth heater 35 are assembled to the outside of the VGF crucible support 29-4, and then the upper insulating layer 30 is disposed around the 5 heaters, and then the heaters and the VGF crucible support 29-4 are enclosed in the upper insulating layer housing 28. The fastening screws 49 are inserted into the screw holes 11-5 of the adapter jig 11, the fastening screws 49 are screwed on the upper insulating layer 30 side, and then the upper insulating layer housing 28 and the VGF crucible support 29-4 are coupled to the adapter jig 11.

The suck-back pipe heater 36 is fitted around the suck-back pipe 29-1, and a suck-back pipe heat-insulating layer 37 is provided outside the suck-back pipe heater 36. A first thermocouple 38, a second thermocouple 39, a third thermocouple 40, and a fourth thermocouple 41 are sequentially disposed in the upper insulating layer 30 and pass through a transfer hole 11-6 of the transfer fixture 11.

Then, the adapting jig 11 connecting the VGF crucible 29 and the thermocouple and the upper insulating layer 30 is connected to the upper furnace cover 2-1 by the fastening screw 49, and the gas leakage along the gap is prevented by the first sealing ring 11-2. Meanwhile, thermocouple wires of the first thermocouple 38, the second thermocouple 39, the third thermocouple 40 and the fourth thermocouple 41 are connected to the outer side of the upper furnace cover 2-1, and sealing of the thermocouple wires and the upper furnace cover 2-1 is achieved. Connecting the differential pressure tube 52 with the balance gas tube 11-1.

Then the upper furnace cover 2-1 is moved to the upper part of the main furnace body support platform 6, then slowly descends, the whole growth system is placed in the upper furnace body 2, and then the upper furnace cover 2-1 and the upper furnace body 2 are connected.

The upper furnace cover 2-1, the upper furnace body 2 and the whole crystal growth system are hoisted to the upper part of the main furnace body 1 through the upper furnace body driving device 4-1, so that the assembly with the main furnace body 1 is realized, and the inverted suction pipe 29-1 is inserted into the center of the synthesis crucible 17. The main furnace body 1 and the base 3 and the main furnace body 1 and the upper furnace body 2 are connected in sequence by screws, so that the furnace body is sealed

2. Preparation of indium phosphide

a. Referring to FIGS. 1 and 8, the entire system is evacuated to 10 via vacuum line 26^-5Pa-10Pa, then filling inert gas into the system through an inflation tube 25, and filling gas with initial pressure of 1.5-2.0 MPa.

b. Starting a main heater 19 and an auxiliary heater 19-1, and heating the synthesis crucible 17 to a synthesis temperature (pure indium 48 and boron oxide I47 in the synthesis crucible 17 are molten); the synthesis crucible 17 is then raised to the crucible position required for synthesis.

c. The first heater 31, the second heater 32, the third heater 33, the fourth heater 34, the fifth heater 35 and the suck-back tube heater 36 are controlled simultaneously so that the temperature in the VGF crucible 29 becomes higher than the melting point of indium phosphide and the boron oxide II47-1 is melted. Then the 2 synthesis injection systems 16 are lowered in sequence for synthesis.

If the optimal synthesis crucible position at this time is such that the back suction pipe 29-1 enters the first melt 20 or the boron oxide I47, inert gas is slowly blown into the VGF crucible 29 through the equilibrium gas pipe 11-1 while synthesizing, and bubbles are injected into the first melt 20 through the back suction pipe 29-1, so that the melt in the back suction pipe 29-1 can be discharged to participate in the synthesis process and prevent the back suction of the first melt 20 or the boron oxide I47 from occurring during synthesis. The bubble rate is 0.5-20 bubbles per second, and the bubbling into the synthesis tube 16-3 and the inverted pipette 29-1 is observed through the lower observation window 14.

After synthesis is complete, the synthesis injection system 16 is raised so that the injection synthesis tube 16-3 is free from the first melt 20. The gas injection into the VGF crucible 29 is stopped so that the bottom of the inverted pipe 29-1 and the synthesis crucible 17 is maintained at 1-5 mm.

d. The pressure in the VGF crucible 29 is slowly reduced through the balance gas pipe 11-1, so that the pressure in the VGF crucible 29 is lower than the pressure value in the main furnace body 1, the pressure reduction is stopped when the pressure difference reaches rhogh, rho is the density of the melt, h is the difference between the maximum rising value of the second melt 45 in the VGF crucible 29 and the liquid level of the first melt 20, the pressure difference between the inside of the VGF crucible 29 and the inside of the furnace body is measured through the pressure difference meter 51, and then the pressure in the VGF crucible 29 is slightly adjusted through the balance gas pipe 11-1 according to the change of the value of the pressure difference meter 51, so that the constant pressure difference is ensured.

e. Then the first heater 31, the second heater 32, the third heater 33, the fourth heater 34 and the fifth heater 35 are controlled to obtain a temperature gradient of more than 20-50K/cm in the second melt 45. Meanwhile, a temperature gradient of 100-150K/cm is obtained in the boron oxide II 47-1.

f. Starting and stopping seed crystal rotation and pulling, and descending the seed crystal until the seed crystal 44 contacts the second melt 45 to carry out crystal growth, wherein the seeding rate is 0.5-20 mm/h, and the corresponding cooling rate is 0.2-25 ℃/h.

The seed rotation and pulling is stopped when the crystal 46 is approximately 5mm in size from the crucible wall of the VGF crucible 29.

g. Readjusting the first heater 31, the second heater 32, the third heater 33, the fourth heater 34 and the fifth heater 35 to make the second melt 45 obtain a temperature gradient of 3-5K/cm, and controlling VGF growth. In this process, the pressure values in the VGF crucible 29 and the main furnace body 1 are always kept at ρ gh.

h. And after the temperature reduction is finished, the second melt 45 in the VGF crucible 29 is solidified. The synthesis crucible 17 is then lowered so that the inverted pipette 29-1 is disengaged from the boron oxide I47. All system heating was stopped.

The entire system was vented to atmospheric pressure. Since the remaining crystals of the seed crystal 44 are joined together, the seed shaft 9 is inverted at this time to disengage the seed shaft 9 from the seed chuck 43, so that the subsequent adapting jig 11 is disengaged from the seed shaft 9. Then the screws between the upper furnace body 2 and the main furnace body 1 are loosened, and the upper furnace body 2 is lifted until the lower end of the inverted suction pipe 29-1 leaves the main furnace body 1. Then the main furnace body 1 is moved to a main furnace body support table 6 through a main furnace body moving motor 4-3. The first thermocouple 38, the second thermocouple 39, the third thermocouple 40 and the fourth thermocouple 41 are loosened from the connection wires to the transfer jig 11, and then the fastening screws 49 are loosened, and the entire crystal growth system is slowly taken out through the upper furnace body 2.

Then, the jig 11 and the VGF crucible 29 are transferred in the crystal growth system, and the jig 11 and the upper insulating layer housing 28 are disassembled, the VGF crucible 29 is taken out, then the VGF crucible 29 is broken, the crystal 46 is taken out, and the boron oxide and the adhered quartz residue on the surface of the crystal 46 are removed by ultrasonic cleaning or the like.

For a 4 inch indium phosphide crystal, the head dislocations were about 105cm^-2(ii) a Dislocation 3cm below the shoulder is about 1000-3000cm^-2The dislocation at the lower part 6cm below the shoulder is about 100-500cm^-2。

The upper part of the system is a VGF growth part, and the lower part of the system is a synthesis part; enter the VGF growth part through the mode of suck-back, the VGF growth part configuration seed rod and observation system simultaneously can also gaseous control. And (3) carrying out crystal introduction and shouldering at the beginning of LEC high-temperature gradient, and then carrying out VGF crystal growth under low-temperature gradient by using the grown crystal, thereby realizing the preparation of high-quality low-defect crystals at higher yield.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the utility model or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the utility model as defined by the appended claims.

Claims (6)

1. A connecting assembly of a VGF crucible in a back suction type compound semiconductor crystal synthesis system comprises an adapter fixture (11) for connecting the VGF crucible (29) and an upper furnace body (2), wherein a back suction pipe (29-1) is arranged below the VGF crucible (29), and is characterized in that: the switching fixture (11) is connected with an upper furnace cover (2-1) of the upper furnace body (2), a clamping ring (11-4) and a cooling column (11-11) which are used for forming a crucible clamping groove (11-10) are arranged on the switching fixture (11), a balance gas pipe (11-1) upwards penetrates through the upper furnace cover (2-1), and the top of the VGF crucible (29) is limited in the crucible clamping groove (11-10).

2. The connecting assembly of a VGF crucible in a downdraft compound semiconductor crystal synthesis system of claim 1, wherein: a first sealing ring (11-2) is arranged between the switching fixture (11) and the upper furnace cover (2-1), and a second sealing ring (11-3) is arranged between the VGF crucible (29) and the crucible clamping groove (11-10).

3. The connecting assembly of a VGF crucible in a downdraft compound semiconductor crystal synthesis system of claim 1, wherein: the balance air pipe (11-1) is connected with the differential pressure pipe (52) and the differential pressure meter (51) is arranged on the differential pressure pipe (52).

4. The connecting assembly of a VGF crucible in a downdraft compound semiconductor crystal synthesis system of claim 1, wherein: the switching fixture (11) is provided with a switching hole (11-6) for connecting a thermocouple.

5. The connecting assembly of a VGF crucible in a downdraft compound semiconductor crystal synthesis system of any one of claims 1 to 4, wherein: an extension pipe (29-2) is arranged at the top of the suck-back pipe (29-1), the extension pipe (29-2) is matched with the inner wall of the VGF crucible (29) to form a storage tank (29-3) for containing boron oxide II (47-1), and the volume of the storage tank (29-3) is larger than that of the boron oxide II (47-1) after melting.

6. The connecting assembly of a VGF crucible in a downdraft compound semiconductor crystal synthesis system of claim 5, wherein: a VGF crucible support (29-4) and a heating system are arranged outside the VGF crucible (29), and the heating system comprises a first heater (31), a second heater (32), a third heater (33), a fourth heater (34) and a fifth heater (35) for heating the VGF crucible (29), and a heater (36) for heating the inverted suction pipe (29-1).

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