Crystal growth apparatus and method

Abstract

According to the crystal growth device and method, a seed crystal cover and a crucible are connected with a power source through electrode units respectively, and due to the fact that the crucible and the seed crystal cover have resistance, at least two electrode units connected with the peripheral wall of the seed crystal cover and the peripheral wall of the crucible are arranged in the circumferential direction at intervals; therefore, after the power supply loads voltage to the crucible and the seed crystal cover, the crucible and the seed crystal cover can uniformly heat, so that compared with thermal radiation indirect heating, the mode of directly loading voltage to heat the crucible and the seed crystal cover can reduce energy consumption and heat loss, and the heat utilization rate is higher; and moreover, the temperatures of the seed crystal cover and the crucible can be adjusted by adjusting the voltage and the power respectively loaded on the seed crystal cover and the crucible, so that the temperature gradient is accurately adjusted, and the growth rate and the quality of the crystal are ensured.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a crystal growth device and method. Background Art

[0002] SiC (silicon carbide) is a representative of the third generation of wide bandgap semiconductors. It has a large bandgap width, high critical breakdown electric field strength, high carrier saturation migration velocity, high thermal conductivity, radiation resistance and corrosion resistance, and excellent chemical thermal stability. It has become an ideal semiconductor material for the production of high-frequency, high-power, high-temperature resistant and radiation-resistant devices. It has very important applications in power electronic devices such as white light lighting, radar communications, aerospace, nuclear reactor systems and military equipment, high-power solid-state microwave devices and solid-state sensors.

[0003] A key process condition in the growth of silicon carbide crystals is heating the crucible and controlling the crucible's temperature gradient, that is, the temperature difference between the raw material area and the growth area in the crucible. However, the current crucible heating methods, whether resistance or inductance, use thermal radiation to indirectly heat the crucible. The heat transfer is somewhat uncontrollable, resulting in inaccurate temperature gradient adjustment, which in turn affects the growth rate and quality of silicon carbide crystals. Summary of the Invention

[0004] The purpose of this application is to provide a crystal growth device and method that can reduce energy consumption and heat loss, improve heat utilization; and can accurately adjust the temperature gradient to ensure the growth rate and quality of the crystal.

[0005] The embodiments of the present application can be implemented as follows:

[0006] In a first aspect, the present invention provides a crystal growth apparatus comprising a crucible, a seed crystal cover, and an electrode unit;

[0007] The seed crystal cover is mounted on one end of the crucible to seal the opening of the crucible;

[0008] The electrode unit is used to connect to a power source;

[0009] At least two electrode units are connected to the outer peripheral wall of the crucible and the outer peripheral wall of the seed crystal cover and are circumferentially spaced apart so as to generate heat when powered.

[0010] In an optional embodiment, two electrode units adjacent to each other in the circumferential direction of the crucible are respectively used to connect to two different phases of a power supply;

[0011] Two electrode units adjacent to each other in the circumferential direction of the seed crystal cover are respectively used to connect to two different phases of a power supply.

[0012] In an optional embodiment, an insulating layer is provided on the contact surface between the seed crystal cover and the crucible.

[0013] In an optional embodiment, the electrode unit includes a connected copper electrode and a graphite electrode;

[0014] The graphite electrode is connected to the crucible or the seed crystal cover;

[0015] The copper electrodes are used to connect to a power source.

[0016] In an optional embodiment, graphite paper is provided between the graphite electrode and the copper electrode.

[0017] In an optional embodiment, the copper electrode has a circulating cooling channel and an inlet and an outlet connected to the circulating cooling channel, the inlet is used to allow the coolant to enter, and the outlet is used to discharge the heated coolant;

[0018] and / or,

[0019] The crystal growth device also includes a heat shield, which surrounds the outside of the crucible and the seed crystal cover and is radially located on the inside of the copper electrode, wherein the heat shield is provided with a plurality of avoidance gaps arranged circumferentially at intervals, and the graphite electrode is passed through the avoidance gaps.

[0020] In an optional embodiment, the graphite electrode is plate-shaped and vertically connected to the outer peripheral wall of the crucible or the outer peripheral wall of the seed crystal cover, and the graphite electrode extends along the axial direction of the crucible or the axial direction of the seed crystal cover;

[0021] Wherein, the graphite electrode on the outer peripheral wall of the crucible is also connected to the end wall of the crucible.

[0022] In an optional embodiment, the crystal growth device also includes an electrically connected controller and a prompter, the controller being used to calculate the real-time resistance of the crucible based on the pressure difference and current between two adjacent electrode units in the circumferential direction of the crucible, and to issue a corrosion prompt signal when the difference between the real-time resistance and the initial resistance of the crucible is greater than a preset difference, and the prompter being used to issue a prompt message based on the corrosion prompt signal.

[0023] In a second aspect, the present invention provides a crystal growth method, which is implemented based on the crystal growth apparatus described in any of the aforementioned embodiments, and the method comprises the following steps:

[0024] S1, placing the raw materials into the crucible, pasting the seed crystal to the seed crystal cover, and installing the seed crystal cover on the crucible;

[0025] S2, connecting the electrode unit to a power source;

[0026] S3, first reducing the pressure in the crucible to the bottom pressure and then increasing it to the preset pressure before turning on the power;

[0027] S4, reducing the pressure in the crucible from the preset pressure to the growth pressure, and controlling the power applied to the seed crystal cover and the crucible respectively so that the temperature difference between the raw material zone and the growth zone in the crucible is the growth temperature difference;

[0028] S5, turn off the power, increase the pressure in the crucible and then perform annealing.

[0029] In an optional embodiment, in step S3, the base pressure is 5e-6 mbar, and the base pressure is maintained for 1 hour; 3500-3000 sccm of protective gas is introduced and the pressure is increased to a preset pressure, which is 400-500 mbar; the power is turned on and heated for 15 hours, the power supply voltage is 10-20 V, the loading power to the crucible is 20-35 kW, and the loading power to the seed crystal cover is 8-15 kW;

[0030] and / or,

[0031] In step S4, the preset pressure is reduced to the growth pressure after 2-4 hours, and the growth pressure is 1-20 mbar; the growth temperature difference is 100-200°C;

[0032] and / or,

[0033] In step S5, a protective gas is introduced into the crucible at a pressure of 500-5000 sccm and increased to 600-800 mbar, and then maintained for 24-48 hours for annealing and cooling.

[0034] Compared with the prior art, the beneficial effects of the embodiments of the present application include, for example:

[0035] By connecting the seed crystal cover and the crucible to the power supply through electrode units respectively, since the crucible and the seed crystal cover have their own resistance, at least two electrode units connecting the outer peripheral wall of the seed crystal cover and the outer peripheral wall of the crucible are arranged circumferentially at intervals. Therefore, after the power supply loads voltage to the crucible and the seed crystal cover, the crucible and the seed crystal cover can be heated evenly. This method of directly loading voltage to make the crucible and the seed crystal cover heat up can reduce energy consumption and heat loss compared to indirect heating by thermal radiation, and has higher heat utilization rate; and the temperature of the seed crystal cover and the crucible can be regulated by adjusting the voltage and power loaded on the seed crystal cover and the crucible respectively, thereby accurately adjusting the temperature gradient and ensuring the growth rate and quality of the crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0037] Figure 1 This is a three-dimensional diagram of a crystal growth device in one embodiment of the present application;

[0038] Figure 2 for Figure 1 A top view of

[0039] Figure 3 for Figure 1 Bottom view of

[0040] Figure 4 for Figure 1 A cross-sectional view after cutting through the central axis of the crucible;

[0041] Figure 5 for Figure 1 Schematic diagram of the electrode unit in;

[0042] Figure 6 for Figure 5 Schematic cross-section of the copper electrode;

[0043] Figure 7 This is a three-dimensional diagram of a crystal growth apparatus in another embodiment of the present application;

[0044] Figure 8 This is a schematic flow chart of a crystal growth method in one embodiment of the present application.

[0045] Icons: 10-crucible; 11-raw material area; 12-growth area; 20-seed crystal cover; 30-electrode unit; 31-copper electrode; 310-circulating cooling channel; 320-inlet; 330-outlet; 32-graphite electrode; 33-graphite paper; 34-first electrode unit; 35-second electrode unit; 40-seed crystal; 50-heat shield; 51-avoidance gap. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0049] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of this application is typically placed when in use. These terms are intended only to facilitate the description of this application and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0050] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0051] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0052] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0053] refer to Figures 1 to 4 The present application discloses a crystal growth device, which includes a crucible 10, a seed crystal cover 20 and an electrode unit 30. The crucible 10, the seed crystal cover 20 and the electrode unit 30 are all made of conductive materials.

[0054] The seed crystal cover 20 is mounted at one end of the crucible 10 to cover the opening of the crucible 10 . The area inside the crucible 10 away from the opening is a raw material area 11 , and the area near the opening is a growth area 12 .

[0055] The electrode unit 30 is used to connect to a power source;

[0056] At least two electrode units 30 are connected to the outer peripheral wall of the crucible 10 and the outer peripheral wall of the seed crystal cover 20 and are spaced apart in the circumferential direction so as to be electrically conductive and generate heat.

[0057] In the application, the seed crystal cover 20 and the crucible 10 are connected to the power supply through the electrode unit 30 respectively. Since the crucible 10 and the seed crystal cover 20 have their own resistance, at least two electrode units 30 connecting the outer peripheral wall of the seed crystal cover 20 and the outer peripheral wall of the crucible 10 are arranged circumferentially at intervals. Therefore, after the power supply loads voltage to the crucible 10 and the seed crystal cover 20, the crucible 10 and the seed crystal cover 20 can be heated evenly. This method of directly loading voltage to make the crucible 10 and the seed crystal cover 20 heat up can reduce energy consumption and heat loss compared to indirect heating by thermal radiation, and has higher heat utilization rate; and the temperature of the seed crystal cover 20 and the crucible 10 can be adjusted by adjusting the voltage and power loaded on the seed crystal cover 20 and the crucible 10 respectively, thereby accurately adjusting the temperature gradient to ensure the growth rate and quality of the crystal.

[0058] In detail, the electrode unit 30 connected to the crucible 10 is used as the first electrode unit 34, and the electrode unit 30 connected to the seed crystal cover 20 is used as the second electrode unit 35;

[0059] Two adjacent electrode units 30 in the circumferential direction of the crucible 10 are respectively used to connect to two different phases of the power supply. Therefore, there is a phase voltage difference between each two adjacent first electrode units 34 in the circumferential direction of the crucible 10, so that current passes through the area of the crucible 10 located between the two adjacent first electrode units 34, thereby causing the area of the crucible 10 through which the current passes to heat up.

[0060] The two electrode units 30 adjacent to each other in the circumferential direction of the seed crystal cover 20 are respectively used to connect to two different phases of the power supply. Therefore, there will be a phase voltage difference between each two adjacent second electrode units 35 in the circumferential direction of the seed crystal cover 20, so that the current passes through the area between the two adjacent second electrode units 35 on the seed crystal cover 20, thereby causing the area on the seed crystal cover 20 where the current passes to heat up.

[0061] It should be noted that power supply can generally be divided into single-phase power supply and three-phase power supply.

[0062] For Crucible 10:

[0063] If the power supply is single-phase, the crucible 10 is connected to the single-phase power supply via 2n first electrode units 34, where n is an integer greater than or equal to 1. Every two adjacent first electrode units 34 in the circumferential direction of the crucible 10 are connected to one power supply. For example, the crucible 10 is directly connected to the positive and negative ports of a single-phase power supply via two first electrode units 34, with the connection between the two first electrode units 34 passing through the central axis of the crucible 10. For another example, if the crucible 10 is connected in parallel to two, three, or more single-phase power supplies via four, six, or eight first electrode units 34, the current distribution is more uniform compared to a single pair of first electrode units 34, thus avoiding localized current concentration and causing more uniform heating of the crucible 10.

[0064] If the power supply is three-phase, the crucible 10 needs to be connected to the three-phase power supply via 3n first electrode units 34. Each first electrode unit 34 is connected to a phase interface of the three-phase power supply, and every three adjacent first electrode units 34 in the circumference of the crucible 10 are connected to a three-phase unit. For example, the crucible 10 is connected to the three phase interfaces of a power supply via three first electrode units 34. For another example, the crucible 10 can be connected to two, three, or four or more three-phase power supplies in parallel via six, nine, or twelve or more first electrode power supplies, thereby achieving more uniform current distribution and avoiding localized current concentration.

[0065] Similarly, for the seed crystal cap 20:

[0066] If the power supply is single-phase, the seed crystal cap 20 is connected to the single-phase power supply through 2n second electrode units 35. Every two adjacent second electrode units 35 in the circumferential direction of the seed crystal cap 20 are connected to one power supply. For example, the seed crystal cap 20 is directly connected to the positive and negative ports of a single-phase power supply through two second electrode units 35, and the connection between the two second electrode units 35 passes through the central axis of the seed crystal cap 20. For another example, the seed crystal cap 20 is connected in parallel to two, three, or more single-phase power supplies through four, six, or eight second electrode units 35. Compared with only one pair of second electrode units 35, the current distribution is more uniform, local current concentration is avoided, and the seed crystal cap 20 heats more evenly.

[0067] If the power supply is three-phase, the seed crystal cover 20 requires 3n second electrode units 35 to connect to the three-phase power supply. Each second electrode unit 35 is connected to a phase interface of the three-phase power supply, and every three adjacent second electrode units 35 in the circumferential direction of the seed crystal cover 20 are connected to a three-phase unit. For example, the seed crystal cover 20 is connected to the three phase interfaces of a power supply via three second electrode units 35. For another example, the seed crystal cover 20 uses six, nine, or twelve or more second electrode power supplies in parallel with two, three, or four or more three-phase power supplies, thereby more evenly distributing the current and avoiding localized current concentration.

[0068] Taking the illustrated embodiment as an example, six first electrode units 34 are connected to the outer wall of the crucible 10. These six first electrode units 34 can be connected in parallel to two three-phase power supplies or three single-phase power supplies. Two second electrode units 35 are connected to the outer wall of the seed crystal cover 20. These two second electrode units 35 are connected to a single-phase power supply.

[0069] Of course, the number of power supplies can also be reduced to one, using a low-voltage, high-current power supply with dual-circuit zone control, i.e., multiple sets of single-phase positive and negative interfaces and / or multiple sets of three-phase interfaces. This can reduce the number of power supplies. For example, the power supply voltage can be 10-20V, and the power configuration can be 60-80kW + 20-30kW. This means that the maximum power used to power the crucible 10 is 60-80kW, and the maximum power used to power the seed crystal cover 20 is 20-30kW.

[0070] It should also be noted that, although directly energizing the crucible 10 and the seed crystal cover 20 will cause the crucible 10 to corrode faster and affect its service life, and the cost of replacing the crucible 10 is higher, in order to meet the requirements of growing higher quality crystals, directly energizing the crucible 10 and the seed crystal cover 20 so that they generate Joule heat themselves can eliminate the need for an external heater, and has a fast temperature response speed, less heat loss, and is convenient for dynamic temperature control. In addition, the structure is simpler and saves space. Therefore, even if the service life of the crucible 10 is sacrificed for these advantages, it is worthwhile.

[0071] In the present application, the contact surface between the seed crystal cover 20 and the crucible 10 has an insulating layer. For example, an insulating coating can be formed only at the seed crystal cover 20 or the opening of the crucible 10; or an insulating coating can be formed at the openings of both the seed crystal cover 20 and the crucible 10. In this way, insulation between the seed crystal cover 20 and the crucible 10 can be achieved, preventing current from being conducted between the seed crystal cover 20 and the crucible 10, thereby preventing arc discharge and abnormal current distribution from affecting the temperature gradient.

[0072] The insulating layer may be an insulating gasket or an insulating coating directly coated on the surface of the seed crystal cover 20 and / or the crucible 10 , as long as insulation between the seed crystal cover 20 and the crucible 10 can be achieved.

[0073] refer to Figure 5In this application, the electrode unit 30 includes a connected copper electrode 31 and a graphite electrode 32. The graphite electrode 32 is connected to the crucible 10 or the seed crystal cover 20. The copper electrode 31 is used to connect to the power supply. As the power input terminal, the copper electrode 31 utilizes the high conductivity and good cooling properties of copper to efficiently conduct the current from the external power supply to the high-temperature heated graphite electrode 32, crucible 10, and seed crystal cover 20, ensuring stable operation under high current. The graphite electrode 32 directly contacts the high-temperature components (i.e., the crucible 10 and seed crystal cover 20). As part of the high-temperature conductive path, it can withstand temperatures exceeding 2000°C and has good conductivity. As part of the heating circuit, it allows the crucible 10 and seed crystal cover 20 to generate heat as a whole through their own resistance.

[0074] Because copper and graphite have different expansion coefficients, stress is easily generated at high temperatures. Therefore, to achieve buffering between copper electrode 31 and graphite electrode 32 at high temperatures, graphite paper 33 is placed between graphite electrode 32 and copper electrode 31. Graphite paper 33 can be 0.5 mm thick and has a certain degree of flexibility, which reduces mechanical damage caused by thermal deformation and buffers thermal expansion differences. It can also effectively reduce the contact resistance between copper electrode 31 and graphite electrode 32, preventing local overheating caused by surface unevenness or oxidation. Moreover, using graphite paper 33 as an intermediate layer between copper electrode 31 and graphite electrode 32 allows for quick disassembly and replacement compared to direct welding or other fixed connection methods between graphite electrode 32 and copper electrode 31.

[0075] refer to Figure 6 The copper electrode 31 has a circulating cooling channel 310 and an inlet 320 and an outlet 330 connected to the circulating cooling channel 310. The inlet 320 is used to introduce coolant, and the outlet 330 is used to discharge the heated coolant. In this way, an external refrigeration module can be connected through the inlet 320 and the outlet 330. The coolant temperature is lowered by the refrigeration module and then enters the copper electrode 31 to absorb heat. The coolant that is heated due to absorbing heat returns to the refrigeration module through the outlet 330. In this way, the heat generated by Joule heat in the copper electrode 31 is taken away by the circulating coolant to prevent it from overheating, deformation or damage, while maintaining the stable operation of the system.

[0076] The graphite electrode 32 is plate-shaped and is vertically connected to the outer peripheral wall of the crucible 10 or the outer peripheral wall of the seed crystal cover 20. The graphite electrode 32 extends along the axial direction of the crucible 10 or the axial direction of the seed crystal cover 20. This facilitates the flow of current over a large circumferential area, forming a stable heating path and ensuring uniform heating across the crucible 10 and the seed crystal cover 20.

[0077] Among them, the graphite electrode 32 on the outer wall of the crucible 10 is also connected to the end wall of the crucible 10, that is, the graphite electrode 32 in the first electrode unit 34 extends to the bottom of the crucible 10, protrudes relative to the bottom wall of the crucible 10, and is connected to the bottom wall of the crucible 10. This ensures that the current can be conducted to the bottom wall of the crucible 10 through the graphite electrode 32, so that the bottom wall of the crucible 10 is heated, thereby ensuring that the raw material is heated at the bottom and radially at the same time, and is also conducive to regulating the radial temperature gradient by loading power.

[0078] Of course, the portions of all the graphite electrodes 32 connected to the bottom wall of the crucible 10 may have gaps therebetween, or they may be connected to each other as shown in the figure.

[0079] The copper electrode 31 in the first electrode unit 34 extends downward to connect to the power supply interface below the crucible 10 ; the copper electrode 31 in the second electrode unit 35 extends upward to connect to the power supply interface above the crucible 10 .

[0080] refer to Figure 7 In another embodiment, the crystal growth device further includes a heat insulating cover 50, which can be made of thermal insulation felt. The heat insulating cover 50 surrounds the outside of the crucible 10 and the seed crystal cover 20, and is located on the inner side of the copper electrode 31 in the radial direction of the crucible 10 and the seed crystal cover 20, wherein the heat insulating cover 50 is provided with a plurality of avoidance gaps 51 arranged circumferentially at intervals, and the graphite electrode 32 is passed through the avoidance gaps 51.

[0081] The heat shield 50 concentrates the heat generated by the seed crystal cover 20 and crucible 10, reducing outward radiation losses and improving heat utilization. It also reduces heat radiation from the crucible 10 and seed crystal cover 20 to the copper electrode 31, providing insulation and preventing direct exposure of the copper electrode 31 to high temperatures, which could lead to performance degradation or damage. The avoidance notch 51 allows the graphite electrode 32 to pass through, ensuring that the graphite electrode 32 can extend from the inside of the heat shield 50 to the outside of the heat shield 50 to connect with the copper electrode 31.

[0082] According to the size of the crucible 10 and the size of the graphite electrode 32, the total area of the crucible 10 and the seed cover 20 connected to the graphite electrode 32 is 100-5000 cm 2 The comprehensive resistance of the crucible 10 is 1.6 mΩ to 6.6 mΩ.

[0083] As the crystal grows, the crucible 10 will gradually corrode. When the crucible 10 corrodes, its resistance will inevitably change. Therefore, by monitoring the voltage difference and current data between adjacent electrode units 30 in the circumferential direction of the crucible 10, the equivalent resistance of the crucible 10 can be calculated in real time and compared with the initial resistance. When the difference exceeds a set threshold, it is determined that the crucible 10 is severely corroded or aged, and an alarm message is issued through a reminder to prompt workers to regularly replace the crucible 10 to ensure the performance of the crucible 10. The initial resistance is the resistance of the crucible 10 before it corrodes, and can also be calculated by monitoring the voltage difference and current data between adjacent electrode units 30 in the circumferential direction of the crucible 10. Therefore, whether the crucible 10 is severely corroded is actually determined by detecting the change in the resistance of the crucible 10, where this change is the aforementioned difference.

[0084] That is, the crystal growth device also includes an electrically connected controller and a prompter, the controller is used to calculate the real-time resistance of the crucible 10 based on the pressure difference and current between two adjacent electrode units 30 in the circumferential direction of the crucible 10, and to issue a corrosion prompt signal when the difference between the real-time resistance and the initial resistance of the crucible 10 is greater than a preset difference, and the prompter is used to issue a prompt message based on the corrosion prompt signal.

[0085] The reminder can be an audible and visual alarm (buzzer + LED flashing), a pop-up prompt on the display (such as the HMI display "Crucible 10 resistance is abnormal, please check the corrosion condition") or a remote communication alarm (sent to the central control system via OPC UA, MQTT, etc.).

[0086] Both the crucible 10 and the seed crystal cover 20 are made of graphite, capable of carrying high currents and generating heat through their own resistance. The surfaces of the crucible 10 and seed crystal cover 20 are polished to reduce impurities and improve conductivity uniformity, thereby avoiding localized high temperatures caused by high current density and extending the service life of the crucible 10 and seed crystal cover 20.

[0087] The outer wall and end wall of the seed crystal cover 20 and the outer wall and end wall of the crucible 10 are chamfered to eliminate right-angled sharp edges, avoid current concentration leading to local discharge or hot spots; relieve thermal stress concentration and reduce the risk of cracks; improve structural strength and enhance thermal shock resistance; facilitate processing and assembly, and improve manufacturing consistency.

[0088] In some embodiments, a portion of adjacent electrode units 30 in the circumferential direction may be connected to the positive electrode, and another portion of adjacent electrode units 30 may be connected to the negative electrode, so that the crucible 10 and the seed crystal cover 20 are powered in series.

[0089] refer to Figure 8 The present application also discloses a crystal growth method based on the above Figures 1 to 6The crystal growth apparatus shown is implemented, and the method includes the following steps:

[0090] S1, placing raw materials into the crucible 10, pasting the seed crystal 40 to the seed crystal cover 20, and installing the seed crystal cover 20 on the crucible 10;

[0091] Specifically, the seed crystal cover 20 can be connected to the crucible 10 by screwing.

[0092] S2, connecting the electrode unit 30 to a power source;

[0093] Specifically, the graphite electrode 32 in the first electrode unit 34 can be integrally formed with the crucible 10, and the graphite electrode 32 in the second electrode unit 35 can be integrally formed with the seed crystal cover 20. Thus, in this step, the copper electrode 31 of the first electrode unit 34 is connected to the main power supply port of the power supply, and the copper electrode 31 of the second electrode unit 35 is connected to the auxiliary power supply port of the power supply. At this time, the entire crucible 10 is in a sealed chamber.

[0094] S3, reducing the pressure in the crucible 10 to the bottom pressure and then increasing it to the preset pressure before turning on the power;

[0095] Specifically, the bottom pressure is 5e-6 mbar, and the bottom pressure is maintained for 1 hour, so that the inside of the crucible 10 is evacuated to an ultra-high vacuum state to remove gases (such as oxygen, water vapor, nitrogen, etc.) in the crucible 10 to prevent oxidation or impurity contamination, thereby providing a clean environment for subsequent high-temperature processes.

[0096] A protective gas is introduced at 3500-3000 sccm and raised to a preset pressure of 400-500 mbar. For example, the protective gas may be argon or nitrogen, providing a stable atmosphere conducive to orderly crystal growth. Reaching 400-500 mbar takes 3-10 hours, gradually increasing the pressure inside crucible 10 from a vacuum state to near-normal pressure, to avoid cracking or seal failure caused by sudden pressure changes.

[0097] Turn on the power and heat for 15 hours. The power voltage is 10-20V, the power for loading the crucible 10 is 20-35KW, and the power for loading the seed crystal cover 20 is 8-15KW. This allows the temperatures of the crucible 10 and the seed crystal cover 20 to rise slowly to prevent local overheating or thermal shock. At the same time, since the loading power of the crucible 10 is greater than the loading power of the seed crystal cover 20, the temperature of the raw material area 11 will be greater than the temperature of the growth area 12, and there will be a temperature difference between the two to control the temperature gradient.

[0098] S4, reducing the pressure in the crucible 10 from the preset pressure to the growth pressure, and controlling the power applied to the seed crystal cover 20 and the crucible 10 respectively so that the temperature difference between the raw material area 11 and the growth area 12 in the crucible 10 is the growth temperature difference;

[0099] Specifically, the pressure is reduced from the preset pressure to the growth pressure of 1-20 mbar over 2-4 hours. The growth temperature difference is 100-200°C. Reducing the pressure from 400-500 mbar to 1-20 mbar creates a low-pressure environment conducive to the biochemical reaction of the raw materials and promotes the migration of the growth atmosphere toward the seed crystal 40. The growth temperature difference, meaning that the temperature of the raw material zone 11 is 100-200°C higher than that of the growth zone 12, creates an axial temperature gradient, driving the growth atmosphere from the high-temperature raw material zone 11 to the low-temperature growth zone 12, resulting in orderly growth along a single direction on the seed crystal 40. The growth time is 100-200 hours, and the growth rate is 75-15 μm / h.

[0100] S5, turning off the power supply, increasing the pressure in the crucible 10 and then performing annealing.

[0101] Specifically, a protective gas is introduced into the crucible 10 at a pressure of 500-5000 sccm and increased to 600-800 mbar, and then maintained for 24-48 hours for annealing and cooling.

[0102] A protective gas such as argon or nitrogen is introduced to create a positive pressure environment to prevent contamination or oxidation from the air duct during the subsequent cooling process. At the same time, a uniform pressure environment is provided for annealing to reduce internal stress in the crystal. A 24-48 hour return can eliminate internal defects in the crystal (such as dislocations, vacancies, etc.), improve crystal integrity, and relieve thermal stress. After annealing, the crystal can be cooled to room temperature by natural cooling or programmed cooling and then removed to achieve crystal growth.

[0103] In summary, compared with the prior art, this application has at least the following advantages:

[0104] 1. Directly heating the crucible 10 and the seed crystal cover 20 can precisely control the temperature gradient and improve the crystal growth efficiency and quality.

[0105] 2. Less heat loss, high energy utilization rate, and more energy saving.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A crystal growth device, characterized in that: It comprises a crucible (10), a seed crystal cover (20) and an electrode unit (30); The seed crystal cover (20) is mounted on one end of the crucible (10) to seal the opening of the crucible (10); The electrode unit (30) is used to connect to a power source; At least two electrode units (30) are connected to the outer peripheral wall of the crucible (10) and the outer peripheral wall of the seed crystal cover (20) and are distributed at intervals in the circumferential direction so as to be able to generate heat when powered.

2. The crystal growth apparatus according to claim 1, wherein: Two electrode units (30) adjacent to each other in the circumferential direction of the crucible (10) are respectively used to connect to two different phases of a power supply; Two electrode units (30) adjacent to each other in the circumferential direction of the seed crystal cover (20) are respectively used to connect to two different phases of a power supply.

3. The crystal growth apparatus according to claim 1, wherein: The contact surface between the seed crystal cover (20) and the crucible (10) is provided with an insulating layer.

4. The crystal growth apparatus according to any one of claims 1 to 3, characterized in that: The electrode unit (30) includes a connected copper electrode (31) and a graphite electrode (32); The graphite electrode (32) is connected to the crucible (10) or the seed crystal cover (20); The copper electrode (31) is used to connect to a power source.

5. The crystal growth apparatus according to claim 4, wherein: There is graphite paper (33) between the graphite electrode (32) and the copper electrode (31).

6. The crystal growth apparatus according to claim 4, wherein: The copper electrode (31) has a circulating cooling channel (310) and an inlet (320) and an outlet (330) in communication with the circulating cooling channel (310), wherein the inlet (320) is used for introducing cooling liquid, and the outlet (330) is used for discharging the heated cooling liquid; and / or, The crystal growth device further includes a heat shield (50), which surrounds the outside of the crucible (10) and the seed crystal cover (20) and is radially located inside the copper electrode (31), wherein the heat shield (50) is provided with a plurality of avoidance gaps (51) arranged at intervals in the circumferential direction, and the graphite electrode (32) is passed through the avoidance gaps (51).

7. The crystal growth apparatus according to claim 4, wherein: The graphite electrode (32) is plate-shaped and vertically connected to the outer peripheral wall of the crucible (10) or the outer peripheral wall of the seed crystal cover (20), and the graphite electrode (32) extends along the axial direction of the crucible (10) or the axial direction of the seed crystal cover (20); The graphite electrode (32) on the outer peripheral wall of the crucible (10) is also connected to the end wall of the crucible (10).

8. The crystal growth apparatus according to claim 1, wherein: The crystal growth device further comprises an electrically connected controller and a prompter, wherein the controller is used to calculate the real-time resistance of the crucible (10) based on the pressure difference and current between two adjacent electrode units (30) in the circumferential direction of the crucible (10), and to issue a corrosion prompt signal when the difference between the real-time resistance and the initial resistance of the crucible (10) is greater than a preset difference, and the prompter is used to issue prompt information according to the corrosion prompt signal.

9. A crystal growth method, implemented based on the crystal growth apparatus according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: S1, placing the raw materials into the crucible (10), pasting the seed crystal (40) to the seed crystal cover (20), and installing the seed crystal cover (20) on the crucible (10); S2, connecting the electrode unit (30) to a power source; S3, reducing the pressure in the crucible (10) to the bottom pressure and then increasing it to the preset pressure before turning on the power supply; S4, reducing the pressure in the crucible (10) from a preset pressure to a growth pressure, and controlling the power applied to the seed crystal cover (20) and the crucible (10) respectively, so that the temperature difference between the raw material area (11) and the growth area (12) in the crucible (10) is the growth temperature difference; S5, turning off the power supply, increasing the pressure in the crucible (10) and then performing annealing.

10. The crystal growth method according to claim 9, wherein In step S3, the bottom pressure is 5e-6 mbar, and the bottom pressure is maintained for 1 hour; 3500-3000 sccm of protective gas is introduced and the pressure is increased to a preset pressure, which is 400-500 mbar; the power is turned on and heated for 15 hours, the power voltage is 10-20 V, the loading power of the crucible (10) is 20-35 kW, and the loading power of the seed crystal cover (20) is 8-15 kW; and / or, In step S4, the preset pressure is reduced to the growth pressure after 2-4 hours, and the growth pressure is 1-20 mbar; the growth temperature difference is 100-200°C; and / or, In step S5, 500-5000 sccm of protective gas is introduced into the crucible (10) and the pressure is increased to 600-800 mbar, and then maintained for 24-48 hours for annealing and cooling.

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