Crystal growth device and crystal preparation method

Abstract

The invention relates to the field of semiconductors, in particular to a crystal growth device and a crystal preparation method. The protective gas interlayer is formed between the side wall of the crucible and the crystal, so that direct contact and adhesion between the side wall of the crucible and the crystal in the crystal growth process are avoided, a material of the crucible is also prevented from permeating into the generated crystal in a solid solution manner, the quality of the generated crystal is improved, and the loss of the material of the crucible is also reduced. Meanwhile, the gas in the shielding gas interlayer is sealed by the melt in the crucible, the fluidity is low, and the stability of the form of the shielding gas interlayer is better maintained, so that the temperature of the thermal field in the crucible is more stable. Meanwhile, by regulating and controlling the components of the protective gas, crystal raw materials can be inhibited from being decomposed due to high temperature of the side wall of the crucible, the phenomenon that the crystal cracks due to the fact that the crystal is extruded by external stress generated by shrinkage of the crucible in the cooling stage is also avoided, the stress in the crystal is also greatly reduced, and the quality and the crystal yield of the crystal are improved.

Description

Technical Field

[0001] The present invention relates to the field of crystals, and in particular to a crystal growth device and a crystal preparation method. Background Art

[0002] There are many types of high-temperature oxide crystals with different properties. They are the basic materials for the production of various detectors and sensors, and they play an important role in national defense, science and technology, and industry. Due to their requirements for atmosphere and temperature, high-temperature oxide crystals are generally grown in precious metal crucibles such as iridium and platinum-rhodium alloys. However, due to the mutual solubility of high-temperature oxide crystals with oxide ceramic materials or the influence of impurity doping, crucibles made of oxide ceramic materials cannot be selected.

[0003] There are non-contact growth methods for high-temperature oxide crystals, such as the Czochralski method (CZ) and the Kyropoulos method (KY), but these methods have low production capacity, are difficult to control, and their quality is limited by the operation level of technicians. In order to improve the production capacity, quality, and automation of oxide crystals, it is often necessary to grow them in a crucible, such as the vertical Bridgman method (VB), vertical temperature gradient solidification method (VGF), directional solidification method (DSS), and casting method (Casting). However, during the entire process of crystal growth using these methods, the crystal and the melt are in direct contact with the crucible. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an oxide crystal growth device and an oxide crystal preparation method, comprising:

[0005] Furnace body, thermal field components, crucible, and protective gas control system;

[0006] The furnace body is provided with the thermal field component, and the thermal field component is used for heating;

[0007] The protective gas control system is connected to the crucible. When a crystal grows in the crucible to form a solid-liquid interface, the protective gas control system forms a protective gas interlayer between the crystal and the side wall of the crucible. The solid-liquid interface is the interface between the melt and the crystal.

[0008] Optionally, the protective gas control system includes: a connecting pipe, a liquid level system, and a pressure detection and control system; the connecting pipe is connected to the crucible, and the protective gas control system introduces protective gas into the crucible through the connecting pipe, and the protective gas forms a protective gas interlayer between the crystal and the side wall of the crucible; the liquid level system is used to detect the thickness of the remaining melt in the crucible, and obtain the liquid pressure generated by the remaining melt in the crucible according to the thickness of the remaining melt; the pressure detection and control system maintains the corresponding pressure and height of the gas in the protective gas interlayer in the crucible according to the liquid pressure obtained by the liquid level system.

[0009] Optionally, the crucible has an air inlet, and the crucible is connected to the protective gas control system through the air inlet.

[0010] Optionally, the air inlet is arranged at the bottom of the crucible side wall or at the edge of the bottom surface of the crucible; when the air inlet is arranged at the bottom of the crucible side wall, the connection between the air inlet and the connecting pipe has an inclination angle.

[0011] Optionally, there is at least one air intake.

[0012] Optionally, the crystal growth device further comprises a crucible support rod, the crucible is connected to the crucible support rod, and the crucible support rod is longitudinally adjustable so that the crucible moves longitudinally along with the crucible support rod.

[0013] Optionally, a heat-insulating layer is provided outside the furnace body; and the pressure detection and control system and the liquid level system are provided outside the heat-insulating layer.

[0014] Optionally, the gas of the protective gas interlayer includes one or more of: H2, Ar, O2, CO2, and N2.

[0015] Optionally, the thermal field component includes a high-frequency induction heating device or a resistance heating device, and the thermal field temperature generated by the thermal field component and the temperature distribution of the upper and lower temperature zones are adjustable.

[0016] Optionally, the crystal growth device is used for growing crystals by a vertical melt method; the crystals include: oxide crystals, telluride crystals, scintillator crystals, ferroelectric crystals or silicon.

[0017] The embodiment of the present invention further provides a method for preparing a crystal using the above-mentioned crystal growth device, comprising:

[0018] Providing a crucible with a seed crystal and a crystal raw material, wherein the seed crystal is placed at the bottom of the crucible, the crystal raw material is located on the surface of the seed crystal, and the diameter of the seed crystal is slightly smaller than the inner diameter of the crucible, so that there is a gap between the seed crystal and the side wall of the crucible;

[0019] A thermal field component forms a thermal field in the furnace body, and the thermal field causes the crystal raw material in the crucible to melt to form a melt;

[0020] The protective gas control system introduces protective gas into the crucible to form a protective gas interlayer between the generated crystal and the side wall of the crucible, wherein the protective gas control system detects the thickness of the residual melt in the crucible in real time, and obtains the liquid pressure generated by the residual melt according to the thickness of the residual melt, and the protective gas control system controls the corresponding pressure and height of the gas in the protective gas interlayer according to the obtained liquid pressure, so that the protective gas interlayer is maintained between the generated crystal and the side wall of the crucible;

[0021] The thermal field in the furnace is controlled to grow the crystal. When the crystal growth is completed, the protective gas interlayer is maintained and the crucible is cooled to room temperature to finally obtain the crystal.

[0022] The embodiment of the present invention further provides a method for preparing a crystal using the above-mentioned crystal growth device, comprising:

[0023] providing a crucible with a crystalline feedstock;

[0024] A thermal field component forms a thermal field in the furnace body, and the thermal field causes the crystal raw material in the crucible to melt to form a melt;

[0025] Adjusting the thermal field in the furnace body so that the melt at the bottom of the crucible spontaneously nucleates from the center area of ​​the bottom and gradually grows outward to form crystals, so that the growing crystals gradually approach the inner wall of the crucible until the diameter of the growing crystals is slightly smaller than the inner diameter of the crucible;

[0026] The protective gas control system introduces protective gas into the crucible to form a protective gas interlayer between the crystal and the side wall of the crucible, wherein when the crystal at the bottom of the crucible grows close to the side wall of the crucible, the protective gas control system introduces protective gas into the crucible, the protective gas control system detects the thickness of the remaining melt in the crucible in real time, and obtains the liquid pressure generated by the remaining melt according to the thickness of the remaining melt, and the protective gas control system controls the corresponding pressure and height of the gas in the protective gas interlayer according to the obtained liquid pressure, so that the protective gas interlayer is maintained between the crystal and the side wall of the crucible;

[0027] The thermal field in the furnace is controlled to grow the crystal. When the crystal growth is completed, the protective gas interlayer is maintained and the crucible is cooled to room temperature to finally obtain the crystal.

[0028] In summary, the advantages and beneficial effects of the present invention are:

[0029] The present invention forms a protective gas interlayer between the side wall of the crucible and the crystal through a protective gas control system connected to the crucible, and controls the pressure and height of the gas in the protective gas interlayer through the protective gas control system, so that when the crystal grows in the crucible to form a solid-liquid interface, the protective gas interlayer is maintained between the crystal and the side wall of the crucible, thereby avoiding direct contact between the side wall of the crucible and the crystal during the crystal growth process, preventing the generated crystal from sticking to the side wall of the crucible, and avoiding the material of the crucible from penetrating into the generated crystal in a solid solution manner, thereby improving the quality of the generated crystal, reducing the loss of the crucible material, and saving costs.

[0030] At the same time, the gas in the protective gas interlayer is sealed by the melt in the crucible, and the thickness of the protective gas interlayer is very small. The gas inside the protective gas interlayer is affected by the friction of the boundary layer and has low fluidity, which better maintains the stability of the protective gas interlayer morphology and makes the thermal field temperature in the crucible more stable. By regulating the gas components inside the protective gas interlayer, the decomposition of the crystal raw materials due to the high temperature of the crucible side wall can be suppressed, and the crystal can be prevented from being squeezed by the external stress generated by the contraction of the crucible during the cooling stage. This not only avoids the cracking of the crystal, but also greatly reduces the stress inside the crystal, thereby improving the quality and yield of the crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of a crystal growth device in an embodiment of the present invention;

[0032] Figure 2 is a schematic structural diagram of a method for preparing a crystal in an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the solid-liquid interface of a method for preparing a crystal in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to specific embodiments.

[0035] The present invention provides an oxide crystal growth device, please refer to Figure 1 ,include:

[0036] Furnace body 10, thermal field component 20, crucible 30, protective gas control system (not shown);

[0037] The furnace body 10 is provided with the thermal field component 20, and the thermal field component 20 is used for heating;

[0038] The protective gas control system (not shown) is connected to the crucible. When the oxide crystals 302 grow in the crucible 30 to form a solid-liquid interface, the protective gas control system (not shown) forms a protective gas interlayer 90 between the crystals 302 and the side wall of the crucible 30. The solid-liquid interface is the interface between the melt 301 and the crystals 302.

[0039] Specifically, in an embodiment of the present invention, the protective gas control system (not shown) includes: a connecting pipe 50, a liquid level system 70, and a pressure detection control system 60; the connecting pipe 50 is connected to the crucible 30, and the protective gas control system (not shown) introduces protective gas into the crucible 30 through the connecting pipe 50, and the protective gas forms a protective gas interlayer 90 between the crystal 302 and the side wall of the crucible 30; the liquid level system 70 is used to detect the thickness of the remaining melt 301 in the crucible 30, and obtain the liquid pressure generated by the remaining melt 301 in the crucible 30 according to the thickness of the remaining melt 301; the pressure detection control system 60 maintains the corresponding pressure and height of the gas in the protective gas interlayer 90 in the crucible 30 according to the liquid pressure obtained by the liquid level system 70.

[0040] In the embodiment of the present invention, a heat-insulating layer 80 is disposed outside the furnace body; the pressure detection and control system 60 and the liquid level system 70 are disposed outside the heat-insulating layer 80 .

[0041] The liquid level system 70 includes a laser liquid level sensor. The liquid level system 70 calculates the remaining thickness of the melt 301 and the pressure value generated by the remaining thickness of the melt 301 by using the density difference between the melt 301 and the crystal 302 .

[0042] In the embodiment of the present invention, the crucible 30 has an air inlet, and the crucible 30 is connected to the protective gas control system (not shown) through the air inlet.

[0043] The gas inlet is used to introduce protective gas into the crucible to form the protective gas interlayer between the crystal 302 and the side wall of the crucible 30 .

[0044] In the embodiment of the present invention, the air inlet is arranged at the bottom of the side wall of the crucible 30 or at the edge of the bottom surface of the crucible 30; when the air inlet is arranged at the bottom of the side wall of the crucible 30, the connection between the air inlet and the connecting pipe 50 has an inclination angle.

[0045] When the air inlet is arranged at the bottom of the side wall of the crucible 30, the inclination angle of the connection between the aperture of the air inlet and the connecting pipe 50 is obtained by calculating the surface tension of the melt 301 and the wetting contact angle of the crucible 30, so that the melt 301 will not flow into the air inlet when there is no external driving force.

[0046] When the air inlet is disposed at the edge of the bottom surface of the crucible 30 , the melt 301 has surface tension and the crystal melt 301 cannot flow into the air inlet, thereby preventing the melt 301 from entering the air inlet and solidifying to block the connecting pipe 50 .

[0047] In an embodiment of the present invention, there is at least one air intake.

[0048] In other embodiments, there are multiple gas inlets, and the multiple gas inlets are evenly distributed on the edge of the bottom surface of the crucible or the bottom of the side wall of the crucible.

[0049] In other embodiments, when there are multiple air inlets, the apertures of the air inlets are appropriately adjusted to facilitate the pressure detection and control system to regulate the pressure and height of the gas in the protective gas interlayer.

[0050] The protective gas interlayer allows the crystal 302 in the crucible to be maintained between the crystal 302 and the side wall of the crucible 30 when the crystal 302 grows to form a solid-liquid interface, thereby avoiding direct contact between the side wall of the crucible 30 and the crystal 302 during the growth of the crystal 302, preventing the generated crystal 302 from sticking to the side wall of the crucible 30, and avoiding the material of the crucible 30 from penetrating into the generated crystal 302 in a solid solution manner, thereby improving the quality of the generated crystal 302, reducing the loss of the crucible 30 material, and saving costs.

[0051] The gas inside the protective gas interlayer is sealed by the melt 301 in the crucible 30, and the thickness of the protective gas interlayer is very small. The gas inside the protective gas interlayer is affected by the friction of the boundary layer, and the fluidity is low, which better maintains the stability of the protective gas interlayer shape; it also makes the thermal field temperature in the crucible 30 more stable. By regulating the gas components inside the protective gas interlayer, it is also possible to inhibit the decomposition of the crystal raw material due to the high temperature of the side wall of the crucible 30, and also avoid the extrusion of the crystal by the external stress generated by the contraction of the crucible 30 during the cooling stage, which not only avoids the cracking of the crystal 302, but also greatly reduces the stress inside the crystal 302, and improves the quality and crystal yield of the crystal 302.

[0052] In the embodiment of the present invention, the crystal growth device further comprises a crucible support rod 40 , the crucible 30 is connected to the crucible support rod 40 , and the crucible support rod 40 is longitudinally adjustable so that the crucible 30 moves longitudinally along with the crucible support rod 40 .

[0053] When the crystal 302 grows, the position of the crucible support rod 40 is adjusted to adjust the position of the crucible 30 in the furnace body 10, thereby adjusting the thermal field temperature of the crucible 30 so that the thermal field temperature meets the growth conditions of the crystal.

[0054] The thermal field component 20 includes a high-frequency induction heating device or a resistance heating device. The thermal field temperature generated by the thermal field component 20 and the temperature distribution of the upper and lower temperature zones are adjustable.

[0055] In the embodiment of the present invention, the thermal field component 20 is provided with a plurality of heating areas, and the plurality of heating areas can be individually controlled so that the thermal field temperature in the furnace body 10 satisfies the growth condition of the crystal 302 .

[0056] In the embodiment of the present invention, the material of the crucible 30 is one of iridium and platinum-rhodium alloy, and the material of the connecting pipe 50 is the same as that of the crucible 30 .

[0057] The protective gas of the protective gas interlayer is one or more of H2, Ar, O2, CO2, and N2.

[0058] By regulating the gas composition inside the protective gas interlayer, the decomposition of the crystal raw material due to the high temperature of the crucible side wall can also be suppressed.

[0059] The crystal growth device is used for growing crystals by a vertical melt method, wherein the vertical melt method includes: vertical Bridgman, vertical temperature gradient method, crucible descent method, directional solidification method or casting method.

[0060] The crystal 302 includes, but is not limited to: an oxide crystal, a telluride crystal, a scintillator crystal, a ferroelectric crystal or silicon, wherein the oxide crystal is gallium oxide or aluminum oxide; the telluride crystal is cadmium telluride, zinc telluride or gallium telluride.

[0061] In the embodiment of the present invention, the crystal 302 is a gallium oxide crystal, and the protective gas of the protective gas interlayer is oxygen, which inhibits the decomposition of the gallium oxide raw material.

[0062] The present invention also provides a method for preparing a crystal, using the above-mentioned crystal growth device, please refer to Figure 2-Figure 3 ,include:

[0063] Step S10, providing a crucible 30 with a seed crystal and a crystal raw material, wherein the seed crystal is placed at the bottom of the crucible 30, the crystal raw material is located on the surface of the seed crystal, and the diameter of the seed crystal is slightly smaller than the inner diameter of the crucible 30, so that there is a gap between the seed crystal and the side wall of the crucible 30.

[0064] In the embodiment of the present invention, the gap between the seed crystal and the side wall of the crucible 30 ranges from 10 μm to 1000 μm, and the gap is determined by the wetting condition between the melt and the crucible and the surface tension of the melt.

[0065] The thickness of the gas inside the protective gas interlayer 90 is very small. The gas inside the protective gas interlayer 90 is affected by the friction of the boundary layer and has low fluidity, which better maintains the stability of the shape of the protective gas interlayer 90 and also makes the thermal field temperature in the crucible 30 more stable.

[0066] In step S20 , the thermal field component 20 forms a thermal field in the furnace body 10 , and the thermal field causes the crystal raw material in the crucible 30 to melt to form a melt 301 .

[0067] In the embodiment of the present invention, the temperature in the furnace body 10 is slowly increased, and the temperature gradient of the thermal field is controlled, so that the surface of the seed crystal and the crystal raw material are gradually melted.

[0068] In step S30, a protective gas control system (not shown) introduces protective gas into the crucible 30 to form a protective gas interlayer 90 between the generated crystal 302 and the side wall of the crucible 30, wherein the protective gas control system (not shown) detects the thickness of the remaining melt 301 in the crucible 30 in real time, and obtains the liquid pressure generated by the remaining melt 301 according to the thickness of the remaining melt 301, and the protective gas control system (not shown) controls the corresponding pressure and height of the gas in the protective gas interlayer 90 according to the obtained liquid pressure, so that the protective gas interlayer 90 is maintained between the generated crystal 302 and the side wall of the crucible 30.

[0069] In an embodiment of the present invention, after the crystal raw material forms the melt 301, a protective gas is slowly introduced to form a protective gas interlayer 90, the pressure of the gas in the protective gas interlayer 90 is equal to the liquid pressure generated by the melt 301, and the crystal growth begins.

[0070] In other embodiments, the pressure of the gas in the protective gas interlayer is slightly lower than the liquid pressure generated by the melt.

[0071] The protective gas control system detects the liquid pressure in the crucible 30 in real time and then controls the corresponding pressure and height of the gas in the protective gas interlayer, so that the melt 301 will neither flow into the interlayer due to insufficient pressure of the gas in the protective gas interlayer 90, nor break through the solid-liquid interface of the crystal melt 301 due to excessive pressure of the gas in the protective gas interlayer 90, thereby affecting the quality of crystal growth; at the same time, the protective gas interlayer 90 is maintained between the crystal and the side wall of the crucible, thereby avoiding direct contact between the side wall of the crucible and the crystal during the crystal growth process, preventing the generated crystal from adhering to the side wall of the crucible, and avoiding the material of the crucible from infiltrating into the generated crystal in a solid solution manner, thereby improving the quality of the generated crystal, reducing the loss of the crucible material, and saving costs.

[0072] Step S40, controlling the thermal field in the furnace body 10 to grow the crystal. After the growth of the crystal 302 is completed, the protective gas interlayer 90 is maintained and the crucible 30 is cooled to room temperature to finally obtain the crystal 302.

[0073] When the growth of the crystal 302 is completed but not cooled to room temperature, the protective gas control system continuously introduces protective gas into the furnace body through the connecting pipe to maintain the existence of the protective gas interlayer until the crystal 302 is completely cooled.

[0074] In the embodiment of the present invention, the crystal growth device further comprises a crucible support rod 40 , the crucible 30 is connected to the crucible support rod 40 , and the crucible support rod 40 is longitudinally adjustable so that the crucible moves longitudinally along with the crucible support rod 40 .

[0075] In the embodiment of the present invention, when the crystal 302 grows, the crucible support rod 40 is longitudinally adjusted so that the lower part of the crucible 30 gradually moves away from the thermal field in the furnace body 10, and then the thermal field temperature of the crucible 30 is adjusted so that the thermal field temperature meets the growth condition of the crystal 302, and then the melt 301 in the crucible 30 gradually grows into the crystal 302.

[0076] In other embodiments, the thermal field temperature in the furnace body is adjusted to a certain gradient by the thermal field component, so as to meet the growth temperature of the melt growing into the crystal 302 .

[0077] In the embodiment of the present invention, during the growth process of the crystal 302 , the pressure of the protective gas is always kept equal to the liquid pressure generated by the melt 301 until the end.

[0078] In other embodiments, during the crystal growth process, the pressure of the protective gas is always kept lower than the liquid pressure generated by the melt until the end.

[0079] The embodiment of the present invention also provides another method for preparing a crystal, using the above-mentioned crystal growth device, comprising:

[0080] Step S100, providing a crucible with crystal raw materials.

[0081] Step S200: A thermal field component forms a thermal field in the furnace body, and the thermal field causes the crystal raw material in the crucible to melt to form a melt.

[0082] Step S300, adjusting the thermal field in the furnace body so that the melt at the bottom of the crucible spontaneously nucleates from the bottom center area and gradually grows outward to form crystals, so that the growing crystals gradually approach the inner wall of the crucible until the diameter of the growing crystals is slightly smaller than the inner diameter of the crucible.

[0083] In an embodiment of the present invention, the thermal field component is controlled to slowly adjust the thermal field temperature in the furnace body so that the temperature of the melt in the crucible has a certain temperature gradient, thereby satisfying the growth conditions of the crystal; at the same time, the position of the crucible is gradually lowered until the crystal spontaneously nucleates and grows outward from the middle area at the bottom of the crucible, and the thermal field temperature in the furnace body and the position of the crucible are further controlled so that the outer diameter of the crystal approaches the inner diameter of the crucible before proceeding to the next step.

[0084] In other embodiments, a seed crystal rod is used to grow a crystal, and the crystal is tapered until the outer diameter of the crystal approaches the inner diameter of the crucible, and then the next step is performed.

[0085] Step S400, the protective gas control system passes protective gas into the crucible to form a protective gas interlayer between the crystal and the side wall of the crucible, wherein when the crystal at the bottom of the crucible grows close to the side wall of the crucible, the protective gas control system passes protective gas into the crucible, the protective gas control system detects the thickness of the remaining melt in the crucible in real time, and obtains the liquid pressure generated by the remaining melt according to the thickness of the remaining melt, and the protective gas control system controls the corresponding pressure and height of the gas in the protective gas interlayer according to the obtained liquid pressure, so that the protective gas interlayer is maintained between the crystal and the side wall of the crucible.

[0086] Step S500, controlling the thermal field in the furnace to grow the crystal, and when the crystal growth is completed, maintaining the protective gas interlayer and cooling the crucible to room temperature to finally obtain the crystal.

[0087] Finally, it is to be noted that any modification or equivalent replacement of part or all of the technical features based on the device structure of the present invention and the technical solution of the described embodiment, which does not deviate from the essence of the corresponding technical solution of the present invention, belongs to the patent scope of the device structure of the present invention and the described implementation scheme.

Claims

1. A crystal growth device, characterized in that: include: Furnace body, thermal field components, crucible, and protective gas control system; The furnace body is provided with the thermal field component, and the thermal field component is used for heating; The protective gas control system is connected to the crucible. When a crystal grows in the crucible to form a solid-liquid interface, the protective gas control system forms a protective gas interlayer between the crystal and the side wall of the crucible. The solid-liquid interface is the interface between the melt and the crystal.

2. A crystal growth device as claimed in claim 1, characterized in that: The protective gas control system includes: a connecting pipe, a liquid level system, and a pressure detection control system; the connecting pipe is connected to the crucible, and the protective gas control system introduces protective gas into the crucible through the connecting pipe, and the protective gas forms a protective gas interlayer between the crystal and the side wall of the crucible; the liquid level system is used to detect the thickness of the remaining melt in the crucible, and obtain the liquid pressure generated by the remaining melt in the crucible according to the thickness of the remaining melt; the pressure detection control system maintains the corresponding pressure and height of the gas in the protective gas interlayer in the crucible according to the liquid pressure obtained by the liquid level system.

3. A crystal growth device as claimed in claim 1, characterized in that: The crucible has an air inlet, and the crucible is connected to the protective gas control system through the air inlet.

4. A crystal growth device as claimed in claim 3, characterized in that: The air inlet is arranged at the bottom of the side wall of the crucible or at the edge of the bottom surface of the crucible; when the air inlet is arranged at the bottom of the side wall of the crucible, the connection between the air inlet and the connecting pipe has an inclination angle.

5. A crystal growth device as claimed in claim 3, characterized in that: There is at least one air intake.

6. A crystal growth device as claimed in claim 1, characterized in that: The crystal growth device further comprises a crucible support rod, the crucible is connected to the crucible support rod, and the crucible support rod is longitudinally adjustable so that the crucible moves longitudinally along with the crucible support rod.

7. A crystal growth device as claimed in claim 1, characterized in that: A heat-insulating layer is arranged outside the furnace body; the pressure detection and control system and the liquid level system are arranged outside the heat-insulating layer.

8. A crystal growth device as claimed in claim 1, characterized in that: The gas of the protective gas interlayer includes: one or more of H2, Ar, O2, CO2, and N2.

9. A crystal growth device as claimed in claim 1, characterized in that: The thermal field component comprises a high-frequency induction heating device or a resistance heating device. The thermal field temperature generated by the thermal field component and the temperature distribution of the upper and lower temperature zones are adjustable.

10. A crystal growth device as claimed in claim 1, characterized in that: The crystal growth device is used for growing crystals by a vertical melt method; the crystals include oxide crystals, telluride crystals, scintillator crystals, ferroelectric crystals or silicon.

11. A method for preparing a crystal, characterized in that: A crystal growth device as claimed in any one of claims 1 to 10, comprising: Providing a crucible with a seed crystal and a crystal raw material, wherein the seed crystal is placed at the bottom of the crucible, the crystal raw material is located on the surface of the seed crystal, and the diameter of the seed crystal is slightly smaller than the inner diameter of the crucible, so that there is a gap between the seed crystal and the side wall of the crucible; A thermal field component forms a thermal field in the furnace body, and the thermal field causes the crystal raw material in the crucible to melt to form a melt; The protective gas control system introduces protective gas into the crucible to form a protective gas interlayer between the generated crystal and the side wall of the crucible, wherein the protective gas control system detects the thickness of the residual melt in the crucible in real time, and obtains the liquid pressure generated by the residual melt according to the thickness of the residual melt, and the protective gas control system controls the corresponding pressure and height of the gas in the protective gas interlayer according to the obtained liquid pressure, so that the protective gas interlayer is maintained between the generated crystal and the side wall of the crucible; The thermal field in the furnace is controlled to grow the crystal. When the crystal growth is completed, the protective gas interlayer is maintained and the crucible is cooled to room temperature to finally obtain the crystal.

12. A method for preparing a crystal, characterized in that: A crystal growth device as claimed in any one of claims 1 to 10, comprising: providing a crucible with a crystalline feedstock; A thermal field component forms a thermal field in the furnace body, and the thermal field causes the crystal raw material in the crucible to melt to form a melt; Adjusting the thermal field in the furnace body so that the melt at the bottom of the crucible spontaneously nucleates from the center area of ​​the bottom and gradually grows outward to form crystals, so that the growing crystals gradually approach the inner wall of the crucible until the diameter of the growing crystals is slightly smaller than the inner diameter of the crucible; The protective gas control system introduces protective gas into the crucible to form a protective gas interlayer between the crystal and the side wall of the crucible, wherein when the crystal at the bottom of the crucible grows close to the side wall of the crucible, the protective gas control system introduces protective gas into the crucible, the protective gas control system detects the thickness of the remaining melt in the crucible in real time, and obtains the liquid pressure generated by the remaining melt according to the thickness of the remaining melt, and the protective gas control system controls the corresponding pressure and height of the gas in the protective gas interlayer according to the obtained liquid pressure, so that the protective gas interlayer is maintained between the crystal and the side wall of the crucible; The thermal field in the furnace is controlled to grow the crystal. When the crystal growth is completed, the protective gas interlayer is maintained and the crucible is cooled to room temperature to finally obtain the crystal.

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