CN116219546A

CN116219546A - Gallium oxide crystal growth device and crystal growth method

Info

Publication number: CN116219546A
Application number: CN202310124047.8A
Authority: CN
Inventors: 李广敏; 张华芹
Original assignee: Shanghai Rhyme New Energy Technology Co ltd
Current assignee: Shanghai Rhyme New Energy Technology Co ltd
Priority date: 2023-02-16
Filing date: 2023-02-16
Publication date: 2023-06-06

Abstract

The invention discloses a gallium oxide crystal growing device, which comprises a crystal growing furnace, wherein the crystal growing furnace is provided with a hollow reaction cavity, a crucible and a heating system are arranged in the reaction cavity, the crystal growing furnace is connected with a transmission system, the transmission system comprises a seed crystal lifting device and a heating system lifting device, the heating system lifting device is connected with the heating system, the crystal growing furnace is connected with an air suction system, a cooling system, an air inlet system and an air exhaust system, and the transmission system, the heating system, the cooling system, the air suction system, the air inlet system and the air exhaust system are respectively connected with a control system. The invention also discloses a growth method of the gallium oxide crystal. The gallium oxide crystal growth device and the crystal growth method provided by the invention can meet the preparation process flow of high-quality large-size gallium oxide crystals, and realize stable and high-quality gallium oxide crystal product production.

Description

Gallium oxide crystal growth device and crystal growth method

Technical Field

The invention relates to the technical field of crystal growth, in particular to a gallium oxide crystal growth device and a crystal growth method.

Background

The gallium oxide crystal material is a fourth generation wide band gap semiconductor material after Si, siC and GaN, 6 crystal phases are known, and the crystal phases comprise 5 stable phases of alpha, beta, gamma and the like and 1 transient phase of kappa-gallium oxide, wherein the beta phase is a thermodynamic stable phase, the melting point is about 1793 ℃, other phases are all converted into beta-gallium oxide at high temperature, and only the beta-gallium oxide crystal can be obtained through growth by a melt method. Beta-gallium oxide has significant advantages over other crystalline phases in bulk single crystal growth.

Gallium oxide compared with silicon carbide and gallium nitride, the gallium oxide-based power device has the characteristics of high voltage resistance, low loss, high efficiency, small size and the like, and is characterized by: under the same pressure resistance, the loss of the silicon carbide-based device is reduced by 86 percent compared with that of the gallium oxide-based device, and the size is only about 1/5 of that of the silicon carbide-based device. Gallium oxide is used as a new generation of power semiconductor material, has large forbidden bandwidth and strong extreme environment resistance, and along with the rapid development of the fields of energy, information, national defense, rail transit, electric automobiles and the like, higher requirements are put forward on the performance of the power semiconductor device, high voltage resistance, low loss and high power devices become the trend of future development, and gallium oxide is expected to play an extremely important role in the field of the future power devices.

At present, gallium oxide crystals are mainly prepared in batches by adopting a guided-mode method technology, and a growth furnace is generally adopted for growth in the process of growing gallium oxide by adopting the guided-mode method. However, in the crystal growth process, the crystal growth environment is easy to change due to factors such as reduction of the volume of melt in the crucible, increase of the volume of crystal at the upper part of a die opening, unpredictable cracking of a heat-insulating material, irregular disturbance of air flow and the like, and if the crystal growth process conditions in a growth furnace cannot be adjusted in real time, the stability of gallium oxide crystal growth is affected, so that defects such as cracking, impurities, polycrystal and the like are generated, and the quality of the grown gallium oxide crystal cannot be ensured.

Disclosure of Invention

In view of the above-mentioned shortcomings existing at present, the present invention provides a gallium oxide crystal growth apparatus and a crystal growth method, which can satisfy the preparation process flow of high quality gallium oxide crystal, and realize stable and high quality gallium oxide crystal product production.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the utility model provides a gallium oxide crystal growing device, includes the crystal growing furnace, the crystal growing furnace is equipped with the cavity reaction chamber, be equipped with crucible and heating system in the reaction chamber, crystal growing furnace connects transmission system, transmission system includes seed crystal pulling device, heating system elevating gear with heating system connects, the crystal growing furnace is connected with air extraction system, cooling system, air intake system and exhaust system, transmission system, heating system, cooling system, air extraction system, air intake system and exhaust system are connected with a control system respectively.

According to one aspect of the invention, the seed crystal pulling device comprises a lifting driving mechanism, a rotary driving mechanism, a seed rod and a connecting shaft, wherein one end of the seed rod penetrates through the crystal growing furnace, the other end of the seed rod is connected with the connecting shaft, and the connecting shaft is connected with the lifting driving mechanism.

According to one aspect of the invention, the top end of the connecting shaft is connected with a weighing device.

According to one aspect of the invention, the heating system lifting device comprises a motor, wherein an output shaft of the motor is connected with a conductive device, the conductive device is connected with a fixing device, and the fixing device is connected with the heating system.

According to one aspect of the invention, the lifting driving mechanism comprises a lifting motor and a screw lifting device, the lifting motor drives the screw lifting device to lift, the outer side of the connecting shaft is connected with a sliding component, and the sliding component is connected with the screw lifting device.

According to one aspect of the invention, the rotary driving mechanism comprises a rotary motor and a synchronous toothed belt, wherein the rotary motor drives the connecting shaft to rotate through the synchronous toothed belt and the magnetic fluid sealing device.

A method for growing gallium oxide crystals, comprising the steps of:

and (2) charging: charging gallium oxide raw material into a crucible, mounting seed crystals on a seed rod, vacuumizing the crystal growth furnace, and filling protective gas;

melting: heating the crystal growth furnace to melt the gallium oxide raw material, and then lowering the seed crystal to the upper part of the die through the seed rod to be welded with the gallium oxide melt;

lifting: the pulling comprises seeding, shouldering and equal-diameter growth, the seed crystal is pulled to finish the seeding process, the temperature and the pulling speed are controlled when the crystal is shouldered to the whole die size, the crystal is subjected to equal-diameter growth until the growth is finished, and the demoulding is finished by rapid pulling, so that the gallium oxide crystal is obtained;

and (3) cooling: after the crystal growth is completed, the crystal is cooled to room temperature.

According to one aspect of the invention, the step of vacuumizing the crystal growing furnace and then filling the protective gas comprises the steps of vacuumizing the reaction cavity and the pipeline to 10Pa through a pumping system and filling the protective gas through a gas inlet system to complete gas replacement.

According to one aspect of the invention, the shielding gas comprises oxygen, carbon dioxide and argon, and the volume ratio of the argon to the oxygen is 20:1-99:1, and the inflation pressure is less than 0.02MPa.

According to one aspect of the invention, the pulling speed of the seeding process is controlled to be 4-15mm/h, and the pulling speed of the heating system is less than 6m/h.

The implementation of the invention has the advantages that: the gallium oxide crystal growth device can accurately control the preparation process and improve the product performance, can realize the high-efficiency low-cost production of high-quality gallium oxide crystal products, and simultaneously ensures the process controllability and stability. The method can accurately and stably control the production temperature, pressure, gas flow, raw gas concentration and other technological parameters during operation, fully ensures the pressure and proper high-temperature environment required by the growth of the beta-gallium oxide crystal by a guided-mode method, realizes the good growth of the gallium oxide crystal, and avoids the generation of defects such as cracking, impurities, polycrystal and the like. The gallium oxide crystal growth device can realize the preparation of gallium oxide crystals with large batch, large size, low cost, high quality and few defects. The gallium oxide prepared by the growth method of the gallium oxide crystal has good product quality and uniformity.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram showing the overall structure of a gallium oxide crystal growing apparatus according to the present invention;

FIG. 2 is a schematic diagram of a process flow of a gallium oxide crystal growing apparatus according to the invention;

fig. 3 is a flow chart of a method for growing gallium oxide crystals according to the invention.

In FIGS. 1-3, 1, a crystal growth furnace; 2. a crucible; 3. seed rods; 4. a connecting shaft; 5. sealing with magnetic fluid; 6. a rotating electric machine; 7. a lifting motor; 8. a first air inlet; 9. a second air inlet; 10. an extraction opening; 11. a tail gas discharge port; 12. a cooling water inlet; 13. a cooling water outlet; 14. a heating system; 15. a heating system lifting device; 16. a screw rod lifting device; 17. and a weighing device.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

As shown in fig. 1, 2 and 3, the gallium oxide crystal growing device comprises a crystal growing furnace 1, wherein the crystal growing furnace 1 is provided with a hollow reaction cavity, a crucible 2 is fixedly arranged in the reaction cavity, a heating system 14 is arranged in the reaction cavity, and the heating system 14 is used for heating raw materials in the crucible 2 to form a melt. The crystal growth furnace 1 is connected with a transmission system, and the transmission system comprises a top seed crystal lifting device and a heating system lifting device which can extend into the crucible 2. The top seed crystal lifting device comprises a lifting driving mechanism, a rotary driving mechanism, a seed rod 3 and a connecting shaft 4. One end of the seed rod 3 penetrates through the crystal growing furnace 1, the other end of the seed rod 3 is connected with the connecting shaft 4, and the connecting shaft 4 is connected with the lifting driving mechanism. Specifically, the lifting driving mechanism comprises a lifting motor 7 and a screw lifting device 16, the lifting motor 7 drives the screw lifting device 16 to lift, a sliding component is connected to the outer side of the connecting shaft 4 and is connected with the screw lifting device 16, so that the seed rod 3 is controlled to descend and lift. The rotary driving mechanism comprises a rotary motor 6, a synchronous toothed belt and a magnetic fluid sealing device 5, and the rotary motor 6 drives the connecting shaft 4 to rotate through the synchronous toothed belt and the magnetic fluid sealing device 5. The heating system lifting device 15 is connected with the heating system and is used for driving the heating system 14 to lift. The crystal growing furnace 1 is connected with an air extraction system 10, a cooling system, an air inlet system and an exhaust system, and the transmission system, the heating system, the cooling system, the air extraction system, the air inlet system and the exhaust system are respectively connected with a control system.

In practical application, the crystal growth furnace is connected with a weighing device 17, and the weighing device 17 is fixed on the top seed crystal lifting device. In particular, the weighing device 17 is connected to the top end of the connecting shaft 4, so as to facilitate weighing of the crystal growth weight.

In practical application, a mold with a slit is arranged in the center of the crucible 2, and gallium oxide raw materials are sucked to the surface of the mold from the mold slit through capillary action after being melted, and then grow. The seed rod 3 is used for the pulling growth of crystals, the seed rod 3 is arranged above the crystal growing furnace 1 and aligned with the center of the opening of the crucible 2, and the heating system 14 is arranged at the periphery of the crucible 2. The lifting of the seed rod 3 and the rotation driving of the seed rod 3 are performed by the lifting driving mechanism and the rotation driving mechanism.

In practical application, be equipped with first air inlet 8, second air inlet 9, extraction opening 10, tail gas discharge port 11, cooling water import 12, cooling water export 13 on the crystal growing furnace 1, first air inlet 8 and second air inlet 9 are connected with air intake system, tail gas discharge port 11 with exhaust system connects, cooling water import 12, cooling water export 13 with cooling system connects. And the air suction opening 10 is connected with an air suction pump for vacuumizing.

In practical application, the bottom of the heating system 14 is connected with the heating system lifting device 15, and the heating system lifting device 15 is connected with the bottom of the hollow reaction cavity. The heating system lifting device 15 comprises a motor, an output shaft of the motor is fixedly provided with a conductive device, the top of the conductive device is provided with a fixing device, the fixing device is connected with the heating system 14, and the structure is designed to provide an installation position for the heating system 14. When the motor is driven, the conductive device, the fixing device and the heating system 14 can be driven to lift together, so that the lifted crystals can be heated in the lifting process. Specifically, the conductive device is made of copper electrodes through welding, the tops of the copper electrodes are fixedly connected with the fixing device, and the bottoms of the copper electrodes are fixedly connected with an output shaft of the motor. The motor drives the heating system 14 to move up and down sequentially through the copper electrode and the fixing device. According to practical situations, the heating system lifting device 15 may be alternatively or designed into any other lifting structure, which is not limited thereto.

In practice, the heating system 14 is an induction heating system. The operation period of the crystal growth furnace 1 adopts an industrial primary S-shaped thermocouple to control heating, and the temperature is set in the control, so that the corresponding temperature can be automatically adjusted. Furthermore, a pressure sensor is arranged in the reaction cavity and can be matched with a control system to accurately control temperature and pressure.

In practical application, the rotary driving mechanism is a magnetic fluid sealing rotating device, and the magnetic fluid sealing rotating device can be a sleeve type hollow shaft magnetic fluid sealing rotating device, can be in sealing connection with the connecting shaft 4, and can stably drive the connecting shaft 4 to rotate. The magnetic fluid seal is adopted, friction between solids does not occur, and the service life can be prolonged.

In practical application, the control system comprises a programmable PLC controller, an alarm and a uploading pattern computer, can be operated manually and automatically, has automatic monitoring and alarming functions, and can realize display, recording and storage of various process parameters such as temperature, vacuum degree, pressure, lifting and the like. Each path of the cooling water circulation system comprises a temperature measuring device, and can perform specific water supply cooling on the heating part and the transmission system. Meanwhile, the cooling water circulation system can be matched with the crystal growth furnace 1 to cool down, so that the cooling rate in the crystal growth furnace 1 is regulated. When overtemperature, low water pressure, overpressure and the like occur, the alarm can give an alarm, and the corresponding equipment is remotely controlled to start, stop and monitor, so that the safe and stable operation of the equipment is ensured. The full-automatic control monitoring and alarming system is adopted, so that the artificial interference is avoided, and the automatic control operation can be realized.

The gallium oxide crystal growth device can accurately control the growth process conditions of gallium oxide crystals in real time, further improve the product performance, realize the high-efficiency low-cost production of high-quality gallium oxide crystal products, ensure the process controllability and stability, and realize the preparation of gallium oxide crystals with large batch, large size, low cost, high quality and few defects.

The invention also comprises a growth method of the gallium oxide crystal, which comprises the following steps: and (2) charging: loading a crucible 2 filled with gallium oxide raw material into a crystal growth furnace 1, mounting seed crystals on a seed rod 3, vacuumizing the inside of the crystal growth furnace 1, and filling protective gas; melting: heating the crystal growth furnace 1 to melt the gallium oxide raw material in the crucible 2; seeding: lowering the seed crystal to the upper part of the mould through a seed rod 3 to be welded with the gallium oxide melt; lifting: the pulling comprises seeding, shouldering and equal-diameter growth, the seed crystal is pulled to finish the seeding process, the temperature and the pulling speed are controlled when the crystal is shouldered to the whole die size, the equal-diameter growth of the crystal is started until the growth is finished, and finally the demoulding is finished by rapid pulling, so that the gallium oxide crystal is obtained; and (3) cooling: after the crystal growth is completed, the crystal is cooled to room temperature. Preferably, the seed crystal is beta-Ga 2O3 crystal.

In practical application, the step of vacuumizing the inside of the crystal growth furnace 1 and then filling the protective gas comprises the steps of vacuumizing the reaction cavity and the pipeline to 10Pa through an air suction system, and filling the protective gas through an air inlet system to complete gas replacement. Wherein the vacuum can be used for completely replacing the gas in the crystal growing furnace 1 by the protective gas. The shielding gas is argon, and in addition, the process gas is oxygen, and the shielding gas can be specifically selected according to the production cost or working conditions. If the volume ratio of the air inlet system is 20:1-99: and 1, filling argon and oxygen, wherein the filling pressure is controlled to be less than 0.02MPa. By charging the shielding gas and the process gas, the pyrolysis of gallium oxide can be suppressed. The gallium oxide raw material in the crucible 2 is heated to about 1800 ℃ by an induction heating system in the crystal growth furnace 1, and meanwhile, the temperature uniformity of a constant temperature area in the crystal growth furnace 1 is controlled to be +/-5 ℃ and the temperature control precision is controlled to be +/-1 ℃.

In practical application, in order to ensure the normal growth of gallium oxide crystals, the pulling speed of the seed crystal is controlled to be about 10mm/h, and the pulling speed of a heating system is less than 6mm/h. The cooling comprises controlling the cooling to be carried out at a rate of about 100 ℃ per hour until the room temperature, so as to prevent the quality of gallium oxide crystals from being influenced by the excessively rapid cooling.

According to the growth method of the gallium oxide crystal, the process parameters such as the production temperature, pressure, gas flow, raw gas concentration and the like are accurately and stably controlled in the operation process, so that the required pressure and a proper high-temperature environment in the process of growing the beta-gallium oxide crystal by a guided mode method are fully ensured, the good growth of the gallium oxide crystal is realized, the defects such as cracking, impurities and polycrystal are avoided, the product quality and uniformity are good, the operability is high, and the method is suitable for preparing the gallium oxide crystal with large batch, large size, low cost and high quality.

Embodiment one:

a method for growing gallium oxide crystals, comprising the steps of: (1) After seed crystal preparation and furnace loading are completed, vacuumizing the furnace and a pipeline to 1X 10Pa through an air extractor, and then filling argon shielding gas through an air inlet control device to complete gas replacement; (2) Heating the gallium oxide raw material in the crucible 2 to about 1800 ℃ by an induction heating device in the crystal growth furnace 1, so as to melt the gallium oxide raw material in the crucible 2; (3) In the seeding stage, seed crystals are lowered to the upper part of a mould through seed crystal rods 3 in a lifting part of a crucible 2 and welded with a melt; (4) the lifting stage comprises seeding, shouldering and equal-diameter growth; pulling the seed crystal at a speed of 4mm/h to finish the seeding process, heating the pulled-out crystal by the cooperation of the heating system lifting device 15, stopping the heating system lifting device 15 and controlling the temperature and the pulling speed when the crystal is shouldered to the whole die size, and starting to grow the crystal in an equal diameter; and controlling the pulling speed to be about 10mm/h until the crystal growth is completed, and finally rapidly pulling to complete demoulding to obtain the gallium oxide crystal. (5) After the crystal growth is finished, the cooling device is controlled to cool at a rate of about 100 ℃ per hour until the temperature reaches the room temperature, so that the quality of gallium oxide crystals is prevented from being influenced by the excessively rapid cooling.

Example two

A method for growing gallium oxide crystals, comprising the steps of: (1) After seed crystal preparation and furnace loading are completed, vacuumizing the furnace and a pipeline to 1X 10Pa through an air extractor, and then filling argon shielding gas through an air inlet control device to complete gas replacement; (2) Heating the gallium oxide raw material in the crucible 2 to about 1800 ℃ by an induction heating device in the crystal growth furnace 1, so as to melt the gallium oxide raw material in the crucible 2; (3) In the seeding stage, seed crystals are lowered to the upper part of a mould through seed crystal rods 3 in a lifting part of a crucible 2 and welded with a melt; (4) the lifting stage comprises seeding, shouldering and equal-diameter growth; pulling the seed crystal at a speed of 4mm/h to finish the seeding process, heating the pulled-out crystal by the cooperation of the heating system lifting device 15, stopping the heating system lifting device 15 and controlling the temperature and the pulling speed when the crystal is shouldered to the whole die size, and starting to grow the crystal in an equal diameter; and controlling the pulling speed to be about 12mm/h until the crystal growth is completed, and finally rapidly pulling to complete demoulding to obtain the gallium oxide crystal. (5) And after the crystal growth is finished, cooling at a rate of about 100 ℃ per hour until the temperature reaches the room temperature to obtain the beta-gallium oxide crystal.

Example III

A method for growing gallium oxide crystals, comprising the steps of: (1) After seed crystal preparation and furnace loading are completed, vacuumizing the furnace and a pipeline to 1X 10Pa through an air extractor, and then filling argon shielding gas through an air inlet control device to complete gas replacement; (2) Heating the gallium oxide raw material in the crucible 2 to about 1800 ℃ by an induction heating device in the crystal growth furnace 1, so as to melt the gallium oxide raw material in the crucible 2; (3) In the seeding stage, seed crystals are lowered to the upper part of a mould through seed crystal rods 3 in a lifting part of a crucible 2 and welded with a melt; (4) the lifting stage comprises seeding, shouldering and equal-diameter growth; pulling the seed crystal at a speed of 12mm/h to finish the seeding process, heating the pulled-out crystal by the cooperation of the heating system lifting device 15, stopping the heating system lifting device 15 and controlling the temperature and the pulling speed when the crystal is shouldered to the whole die size, and starting to grow the crystal in an equal diameter; and controlling the pulling speed to be about 15mm/h until the crystal growth is completed, and finally rapidly pulling to complete demoulding to obtain the gallium oxide crystal. (5) And after the crystal growth is finished, cooling at a rate of about 100 ℃ per hour until the temperature reaches the room temperature to obtain the beta-gallium oxide crystal.

By detecting the beta-gallium oxide crystals obtained in the first embodiment, the second embodiment and the third embodiment, the product quality and uniformity are good, and defects such as cracking, impurities and polycrystal are avoided.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The utility model provides a gallium oxide crystal growing device, includes the crystal growing furnace, the crystal growing furnace is equipped with the cavity reaction chamber, be equipped with crucible and heating system in the reaction chamber, a serial communication port, the crystal growing furnace connects transmission system, transmission system includes seed crystal pulling device, heating system elevating gear with heating system connects, the crystal growing furnace is connected with air extraction system, cooling system, air intake system and exhaust system, transmission system, heating system, cooling system, air extraction system, air intake system and exhaust system are connected with a control system respectively.

2. A gallium oxide crystal growing apparatus according to claim 1, wherein the seed crystal pulling apparatus comprises a lifting drive mechanism, a rotary drive mechanism, a seed rod and a connecting shaft, one end of the seed rod penetrates through the crystal growing furnace, the other end of the seed rod is connected with the connecting shaft, and the connecting shaft is connected with the lifting drive mechanism.

3. A gallium oxide crystal growing apparatus according to claim 2, wherein the top end of the connecting shaft is connected to a weighing device.

4. A gallium oxide crystal growing apparatus according to claim 1, wherein the heating system lifting device comprises a motor, an output shaft of the motor is connected to a conductive device, the conductive device is connected to a fixing device, and the fixing device is connected to the heating system.

5. A gallium oxide crystal growing apparatus according to claim 1, wherein the lifting drive mechanism comprises a lifting motor and a screw lifting device, the lifting motor drives the screw lifting device to lift, a sliding component is connected to the outer side of the connecting shaft, and the sliding component is connected to the screw lifting device.

6. A gallium oxide crystal growing apparatus according to claim 1, wherein the rotary driving mechanism includes a rotary electric machine and a timing belt, the rotary electric machine driving the connecting shaft to rotate through the timing belt and the magnetic fluid sealing device.

7. A gallium oxide crystal growth method, characterized by comprising the steps of:

8. The method of claim 7, wherein the step of evacuating the inside of the crystal growth furnace and then filling the protection gas comprises evacuating the reaction chamber and the pipe to 10Pa through the evacuation system, and filling the protection gas through the gas inlet system to complete the gas replacement.

9. A gallium oxide crystal growth method according to claim 8, wherein the shielding gas comprises oxygen and argon, and the volume ratio of the argon to the oxygen is 20:1-99:1, and the inflation pressure is less than 0.02MPa.

10. A gallium oxide crystal growing method according to claim 7, wherein the pulling rate of the seeding process is controlled to be 4-15mm/h, and the pulling rate of the heating system is less than 6m/h.