Apparatus for growing large-size gallium oxide crystal, and growth method

Abstract

The present application relates to the technical field of crystal growth apparatuses, and discloses an apparatus for growing a large-size gallium oxide crystal, and a growth method. The apparatus comprises: a single crystal furnace body comprising a seed crystal lifting and rotating mechanism; a thermal insulation device that can be arranged in the single crystal furnace, the thermal insulation device comprising a thermal insulation container and a thermal insulation top plate; a metal crucible that can be placed in the thermal insulation container; a first driving mechanism used for driving the metal crucible to rotate; an induction heating coil sleeved outside the thermal insulation container; and a horizontally arranged conical ring connected to an output end of the seed crystal lifting and rotating mechanism by means of a connecting assembly. The growth method comprises: first, melting a gallium oxide raw material, lowering a conical ring, then generating a high-quality seed crystal by means of controlled nucleation, and expanding the seed crystal to form a crystal facet; upon confirming that the crystal facet is in stable contact with the conical ring, lifting the conical ring for equal-diameter growth control; and when the crystal reaches a predetermined size, terminating the process. The present invention can effectively avoid twin defects in traditional edge-defined film-fed growth or Czochralski methods, allowing for growth of crystals having higher quality.

Description

An apparatus and method for growing large-size gallium oxide crystals Technical Field

[0001] This application relates to the field of crystal growth equipment technology, and in particular to an apparatus and method for growing large-size gallium oxide crystals. Background Technology

[0002] With the continuous development of technology, power devices fabricated using wide-bandgap semiconductors are receiving increasing attention as next-generation devices to replace silicon devices. Among the many wide-bandgap semiconductor materials, silicon carbide (SiC) currently dominates the field of power devices, followed by gallium nitride (GaN). However, gallium oxide (Ga2O3) has recently attracted considerable attention due to its larger bandgap compared to SiC and GaN, demonstrating a broader market prospect for applications.

[0003] Among the methods for growing gallium oxide crystals, the dominant ones are the mold-guided method, the Czochralski method, the vertical Bridgman method, and the casting method. However, these methods all have certain limitations. In the mold-guided method and the Czochralski method, twins are easily generated on the (100) crystal plane when growing large-size crystals, resulting in smaller product sizes and greater difficulty in controlling the growth process. Moreover, in the mold-guided method, the amount of iridium used is much greater than in other gallium oxide crystal growth methods due to the presence of the mold. In the vertical Bridgman method, the crystal is grown from bottom to top in a crucible. During the growth process, the crystal and the crucible wall are closely attached. During the cooling process, the shrinkage of the crucible is greater than that of the crystal, generating a large amount of mechanical stress inside the crystal, which can easily cause crystal cracking and reduce crystal quality. At the same time, it is extremely difficult to separate the crucible and the crystal. Although the casting method also grows in a crucible, the crucible and the crystal are separated throughout the growth process. The stress during the cooling process is small, and the crucible and the crystal are relatively easy to separate. It is currently the optimal solution for growing gallium oxide. Even so, the casting method is still limited by the size of the crucible. To increase production, the required crucible is larger and deeper, the amount of iridium raw material used to prepare the crucible is too large, and the process of controlling the separation of the crucible and the crystal is also difficult to implement.

[0004] In summary, existing gallium oxide crystal growth methods have many problems, and a new technical solution is urgently needed to overcome these defects in order to meet the growing market demand for gallium oxide crystals. Summary of the Invention

[0005] The purpose of this application is to provide an apparatus and method for growing large-size gallium oxide crystals, so as to solve the problems existing in the prior art and improve the efficiency of growing large-size gallium oxide crystals.

[0006] To achieve the above objectives, this application provides the following solution:

[0007] This application provides an apparatus for growing large-size gallium oxide crystals, including:

[0008] A single crystal furnace body, wherein the single crystal furnace body includes a seed crystal lifting and rotating mechanism;

[0009] A heat preservation device that can be installed inside the single crystal furnace body, the heat preservation device including a heat preservation container and a heat preservation top plate for covering the top of the heat preservation container;

[0010] A metal crucible that can be placed inside the insulated container;

[0011] A first driving mechanism is used to drive the metal crucible to rotate. The first driving mechanism includes a first driving device and a support plate. The support plate is fixedly connected to the output shaft of the first driving device. The support plate is located inside the heat-insulating container and is used to support the metal crucible. The output shaft passes through the single crystal furnace body and the heat-insulating container.

[0012] An induction heating coil is fitted outside the insulated container, and the induction heating coil is used to induction heat the metal crucible inside the insulated container;

[0013] A horizontally positioned conical ring, made of iridium or a platinum-rhodium alloy with a rhodium content ≥20%, has an outer and inner diameter that gradually decreases from top to bottom. The conical ring is connected to the output end of a seed crystal lifting and rotating mechanism via a connecting assembly. The seed crystal lifting and rotating mechanism drives the conical ring to rotate and move up and down, and can also weigh the conical ring. The conical ring can enter the metal crucible.

[0014] Preferably, the connecting assembly includes a fixing frame, which is connected to the output end of the seed crystal lifting and rotating mechanism via a first connecting wire. The conical ring is connected to the fixing frame via at least three circumferentially distributed second connecting wires, and the fixing frame is parallel to the conical ring. The material of the second connecting wire is iridium or platinum-rhodium alloy.

[0015] Preferably, the heat-insulating top plate is provided with a first through hole corresponding to the second connecting wire, and the second connecting wire passes through the corresponding first through hole.

[0016] Preferably, the connecting assembly includes a third connecting wire and at least three fourth connecting wires. The top end of the third connecting wire is connected to the output end of the seed crystal lifting and rotating mechanism. The top end of each fourth connecting wire is fixedly connected to the bottom end of the third connecting wire, and the bottom end of the fourth connecting wire is fixedly connected to the conical ring. The material of the fourth connecting wire is iridium or platinum-rhodium alloy.

[0017] Preferably, a second through hole is provided on the heat-insulating top plate corresponding to the third connecting wire, and the third connecting wire passes through the second through hole.

[0018] Preferably, the cone angle of the conical ring is 45° to 75°.

[0019] Preferably, an observation port is provided on the insulated top plate.

[0020] Preferably, the diameter of the metal crucible is 80mm to 300mm and the height is 30mm to 120mm.

[0021] Preferably, the diameter of the conical ring is 50% to 75% of the diameter of the metal crucible.

[0022] Preferably, the height of the conical ring is 5mm to 10mm.

[0023] This application also provides a method for growing large-size gallium oxide crystals, based on the above-described apparatus for growing large-size gallium oxide crystals, including the following steps:

[0024] (1) Place the heat preservation device inside the single crystal furnace, then put the gallium oxide raw material into the metal crucible, then place the metal crucible into the heat preservation container, and then cover the heat preservation top plate on the heat preservation container.

[0025] (2) Turn on the induction heating coil to induction heat the metal crucible so that the gallium oxide raw material in the metal crucible is completely melted to form gallium oxide melt;

[0026] (3) Adjust the power of the induction heating coil so that the temperature at the center of the surface of the gallium oxide melt is close to the melting point, and drive the metal crucible to rotate through the first driving mechanism;

[0027] (4) Drive the conical ring to descend through the seed crystal lifting and rotating mechanism until the conical ring is immersed 3 mm to 8 mm from the surface of the gallium oxide melt;

[0028] (5) By controlling nucleation, a high-quality seed crystal is generated at the center of the surface of the gallium oxide melt, and the high-quality seed crystal is controlled to expand stably to form a crystal, and the crystal is further expanded until the crystal contacts the inner wall of the conical ring.

[0029] (6) After confirming that the crystal is in stable contact with the conical ring by direct observation and the change in the weighing value of the seed crystal lifting and rotating mechanism, the conical ring is lifted by the seed crystal lifting and rotating mechanism at a speed of 0.5 mm / h to 5 mm / h to enter the constant diameter growth control stage.

[0030] (7) After the crystal grows to a predetermined size, gradually increase the power of the induction heating coil and increase the rising speed of the conical ring to make the crystal end and separate from the gallium oxide melt;

[0031] (8) After the thermal field cools down, the crystal growth is completed.

[0032] This application achieves the following technical advantages over the prior art:

[0033] The equipment and method for growing large-size gallium oxide crystals in this application combine the advantages of high nucleation quality of casting method and Czochralski equal diameter control technology and low thermal stress of out-of-cab growth, which can effectively avoid twin defects in traditional mold or Czochralski methods and grow higher quality crystals.

[0034] Furthermore, by combining continuous feeding technology, the crystal height can be further increased, thereby increasing the single-furnace capacity and providing strong support for the industrialization of gallium oxide.

[0035] Furthermore, compared to the mold-guided method, this application reduces the amount of iridium used and its losses, thus lowering production costs. Simultaneously, it solves problems such as limited crystal growth thickness, low yield, and the difficulty in resolving twinning in gallium oxide crystals. Compared to the casting method, this application avoids the mechanical stress affecting the crystal structure from crucible compression and solves the problems of difficulty in removing the crystal from the crucible after growth and the significant influence of crucible size on crystal dimensions. Compared to the Czochralski method, it reduces the difficulty of shoulder formation and decreases twinning.

[0036] Furthermore, the seed crystal lifting and rotating mechanism enables the weighing, rotation, and lifting control of the conical ring, achieving precise monitoring and adjustment of the crystal growth process.

[0037] Furthermore, by controlling nucleation and controlling constant diameter growth, the quality and stability of crystal growth are ensured.

[0038] Furthermore, this application provides two options for connection components, which can be adjusted according to the actual equipment situation. One is to connect the conical ring and the seed crystal lifting and rotating mechanism through a fixing frame and multiple connecting wires; the other is to directly connect the conical ring and the seed crystal lifting and rotating mechanism with a suspension structure composed of oblique wires, thereby increasing the applicability of the equipment. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 is a schematic diagram of the structure of a device for growing gallium oxide crystals to a single size according to an embodiment of this application;

[0041] Figure 2 is a schematic diagram of the structure of the device for growing gallium oxide crystals to a larger size according to an embodiment of this application;

[0042] Figure 3 is a schematic diagram of the structure of the device for growing gallium oxide crystals to a single size according to an embodiment of this application;

[0043] Figure 4 is a schematic diagram of the equipment used to grow large-size gallium oxide crystals according to Embodiment 2 of this application;

[0044] In the figure: 1. Single crystal furnace body; 2. Seed crystal lifting and rotating mechanism; 3. Insulation container; 4. Induction heating coil; 5. Insulation top plate; 6. Support plate; 7. First driving device; 8. Metal crucible; 9. Fixing frame; 10. First connecting wire; 11. Second connecting wire; 12. Third connecting wire; 13. Fourth connecting wire; 14. Conical ring. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] The purpose of this application is to provide an apparatus and method for growing large-size gallium oxide crystals, so as to solve the problems existing in the prior art and improve the efficiency of growing large-size gallium oxide crystals.

[0047] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] As shown in Figures 1 to 3, this embodiment provides an apparatus for growing large-size gallium oxide crystals, including:

[0050] The single crystal furnace body 1 includes a seed crystal lifting and rotating mechanism 2.

[0051] A heat preservation device that can be installed inside the furnace body 1 of a single crystal furnace includes a heat preservation container 3 and a heat preservation top plate 5 for covering the top of the heat preservation container 3.

[0052] A metal crucible 8 that can be placed inside an insulated container 3;

[0053] The first driving mechanism is used to drive the metal crucible 8 to rotate. The first driving mechanism includes a first driving device 7 and a support plate 6. The support plate 6 is fixedly connected to the output shaft of the first driving device 7. The support plate 6 is located inside the heat preservation container 3 and is used to support the metal crucible 8. The output shaft passes through the single crystal furnace body 1 and the heat preservation container 3.

[0054] An induction heating coil 4 is fitted outside the insulation container 3. The induction heating coil 4 is used to induction heat the metal crucible 8 inside the insulation container 3.

[0055] A horizontally positioned conical ring 14 is made of iridium or a platinum-rhodium alloy with a rhodium content ≥20%. The outer and inner diameters of the conical ring 14 gradually decrease from top to bottom. The conical ring 14 is connected to the output end of the seed crystal lifting and rotating mechanism 2 via a connecting assembly. The seed crystal lifting and rotating mechanism 2 is used to drive the conical ring 14 to rotate and lift, and it can also weigh the conical ring 14. The conical ring 14 can enter the metal crucible 8.

[0056] It is worth noting that both the single crystal furnace body 1 and the seed crystal lifting and rotating mechanism 2 with weighing function have mature equipment. Therefore, this embodiment will not elaborate on the specific structure and working principle of the single crystal furnace body 1 and the seed crystal lifting and rotating mechanism 2 with weighing function. The reason why the outer diameter and inner diameter of the conical ring 14 gradually decrease from top to bottom is that the conical ring 14 can hold the large-sized gallium oxide crystal that has been grown, ensuring that the large-sized gallium oxide crystal will not fall off the conical ring 14.

[0057] In an optional embodiment, a preferred embodiment includes a fixing frame 9, which is connected to the output end of the seed crystal lifting and rotating mechanism 2 via a first connecting wire 10. The conical ring 14 is connected to the fixing frame 9 via at least three circumferentially distributed second connecting wires 11, and the fixing frame 9 is parallel to the conical ring 14. The material of the second connecting wires 11 is iridium or platinum-rhodium alloy. The number of second connecting wires 11 is preferably 3 to 6.

[0058] In the optional scheme of this embodiment, it is more preferred that the heat-insulating top plate 5 is provided with a first through hole corresponding to the second connecting wire 11, and the second connecting wire 11 passes through the corresponding first through hole.

[0059] In the optional schemes of this embodiment, it is more preferred that the cone angle of the cone ring 14 is 45° to 75°; the cone angle of the cone ring 14 is matched and selected according to the initial crystal interface shape generated by different thermal fields, in order to reduce contact stress.

[0060] In the optional embodiments of this example, a more preferred option is that the heat-insulating top plate 5 is provided with an observation port, through which the metal crucible 8 and the conical ring 14 can be observed.

[0061] In the optional embodiments of this example, the height of the metal crucible 8 is preferably 30mm to 120mm.

[0062] Example 2

[0063] As shown in Figure 4, this embodiment provides an apparatus for growing large-size gallium oxide crystals. The apparatus for growing large-size gallium oxide crystals in this embodiment is the same as the apparatus for growing large-size gallium oxide crystals in Embodiment 1 in terms of structure and working principle, with the only difference being:

[0064] The connecting assembly includes a third connecting wire 12 and at least three circumferentially distributed fourth connecting wires 13. The top end of the third connecting wire 12 is connected to the output end of the seed crystal lifting and rotating mechanism 2. The top end of each fourth connecting wire 13 is fixedly connected to the bottom end of the third connecting wire 12, and the bottom end of the fourth connecting wire 13 is fixedly connected to the conical ring 14. The material of the fourth connecting wire 13 is iridium or platinum-rhodium alloy.

[0065] In this embodiment, a second through hole is provided on the heat-insulating top plate 5 corresponding to the third connecting wire 12, and the third connecting wire 12 passes through the second through hole.

[0066] It is worth noting that the specific structure of the connecting components in this embodiment can form a balanced suspension structure, which is then connected to the seed crystal lifting and rotating mechanism 2. This approach can eliminate the crucible rotation function, but it increases the force on each of the third connecting wires 12 and the fourth connecting wires 13, significantly increasing the risk of damage. Therefore, it can be used but is not recommended.

[0067] Example 3

[0068] This embodiment provides a method for growing large-size gallium oxide crystals, based on the equipment for growing large-size gallium oxide crystals in Embodiment 1 or Embodiment 2, and includes the following steps:

[0069] (1) Place the heat preservation device inside the single crystal furnace body 1, then put the gallium oxide raw material into the metal crucible 8, then put the metal crucible 8 into the heat preservation container 3, and then cover the heat preservation container 3 with the heat preservation top plate 5.

[0070] (2) Turn on the induction heating coil 4 to induction heat the metal crucible 8 so that the gallium oxide raw material in the metal crucible 8 is completely melted to form gallium oxide melt;

[0071] (3) Adjust the power of the induction heating coil 4 so that the temperature at the center of the surface of the gallium oxide melt is close to the melting point, and drive the metal crucible 8 to rotate through the first driving mechanism;

[0072] (4) Drive the conical ring 14 down through the seed crystal lifting and rotating mechanism 2 until the conical ring 14 is immersed 3mm to 8mm from the surface of the gallium oxide melt;

[0073] (5) Through nucleation control, a high-quality seed crystal is generated at the center of the surface of the gallium oxide melt. It should be noted that the high-quality seed crystal generated at this time is encircled by the conical ring 14, and the high-quality seed crystal is controlled to expand stably to form a crystal, and the crystal is further expanded until the crystal contacts the inner wall of the conical ring 14.

[0074] (6) By directly observing and observing the change in the weighing value of the seed crystal lifting and rotating mechanism 2 (after the crystal surface and the conical ring 14 are in stable contact, the crystal surface will provide a certain support for the conical ring 14, which will reduce the weighing value of the seed crystal lifting and rotating mechanism 2), after confirming that the crystal surface and the conical ring 14 are in stable contact (as shown in Figure 2), the conical ring 14 is lifted by the seed crystal lifting and rotating mechanism 2 at a speed of 0.5 mm / h to 5 mm / h, and the constant diameter growth control stage is entered.

[0075] (7) After the crystal grows to the predetermined size, gradually increase the power of the induction heating coil 4 and increase the rising speed of the conical ring 14 to make the crystal end and separate from the gallium oxide melt (as shown in Figure 3).

[0076] (8) After the thermal field cools down, the crystal growth is completed.

[0077] It is worth noting that the nucleation control mentioned in step (5) is an existing mature technology. For details, please refer to the detailed description in patent application CN114561701A. It will not be elaborated further in this embodiment.

[0078] In the optional schemes of this embodiment, it is more preferred that the crucible height can be reduced to a certain extent and the single furnace output of crystal can be further increased by using continuous feeding technology during the crystal growth process. Continuous feeding technology is an existing technology, and for details, please refer to the detailed description in patent CN221480153U. It will not be elaborated on in this embodiment.

[0079] This application uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. In summary, the content of this specification should not be construed as a limitation of this application.

Claims

1. An apparatus for growing large-size gallium oxide crystals, characterized in that, include: A single crystal furnace body, wherein the single crystal furnace body includes a seed crystal lifting and rotating mechanism; A heat preservation device that can be installed inside the single crystal furnace body, the heat preservation device including a heat preservation container and a heat preservation top plate for covering the top of the heat preservation container; A metal crucible that can be placed inside the insulated container; A first driving mechanism is used to drive the metal crucible to rotate. The first driving mechanism includes a first driving device and a support plate. The support plate is fixedly connected to the output shaft of the first driving device. The support plate is located inside the heat-insulating container and is used to support the metal crucible. The output shaft passes through the single crystal furnace body and the heat-insulating container. An induction heating coil is fitted outside the insulated container, and the induction heating coil is used to induction heat the metal crucible inside the insulated container; A horizontally positioned conical ring, made of iridium or a platinum-rhodium alloy with a rhodium content ≥20%, has an outer and inner diameter that gradually decreases from top to bottom. The conical ring is connected to the output end of a seed crystal lifting and rotating mechanism via a connecting assembly. The seed crystal lifting and rotating mechanism drives the conical ring to rotate and move up and down, and can also weigh the conical ring. The conical ring can enter the metal crucible.

2. The apparatus for growing large-size gallium oxide crystals according to claim 1, characterized in that: The connecting assembly includes a fixing frame, which is connected to the output end of the seed crystal lifting and rotating mechanism via a first connecting wire. The conical ring is connected to the fixing frame via at least three circumferentially distributed second connecting wires, and the fixing frame is parallel to the conical ring. The material of the second connecting wire is iridium or platinum-rhodium alloy.

3. The apparatus for growing large-size gallium oxide crystals according to claim 2, characterized in that: The heat-insulating top plate is provided with a first through hole corresponding to the second connecting wire, and the second connecting wire passes through the corresponding first through hole.

4. The apparatus for growing large-size gallium oxide crystals according to claim 1, characterized in that: The connecting assembly includes a third connecting wire and at least three fourth connecting wires. The top end of the third connecting wire is connected to the output end of the seed crystal lifting and rotating mechanism. The top end of each fourth connecting wire is fixedly connected to the bottom end of the third connecting wire, and the bottom end of the fourth connecting wire is fixedly connected to the conical ring. The material of the fourth connecting wire is iridium or platinum-rhodium alloy.

5. The apparatus for growing large-size gallium oxide crystals according to claim 4, characterized in that: The heat-insulating top plate is provided with a second through hole corresponding to the third connecting wire, and the third connecting wire passes through the second through hole.

6. The apparatus for growing large-size gallium oxide crystals according to claim 1, characterized in that: The cone angle of the conical ring is 45° to 75°.

7. The apparatus for growing large-size gallium oxide crystals according to claim 1, characterized in that: An observation port is provided on the insulated top plate.

8. The apparatus for growing large-size gallium oxide crystals according to claim 1, characterized in that: The height of the metal crucible is 30mm to 120mm.

9. A method for growing large-size gallium oxide crystals, characterized in that, The apparatus for growing large-size gallium oxide crystals according to any one of claims 1-8 includes the following steps: (1) Place the heat preservation device inside the single crystal furnace, then put the gallium oxide raw material into the metal crucible, then place the metal crucible into the heat preservation container, and then cover the heat preservation top plate on the heat preservation container. (2) Turn on the induction heating coil to induction heat the metal crucible so that the gallium oxide raw material in the metal crucible is completely melted to form gallium oxide melt; (3) Adjust the power of the induction heating coil so that the temperature at the center of the surface of the gallium oxide melt is close to the melting point, and drive the metal crucible to rotate through the first driving mechanism; (4) Drive the conical ring to descend through the seed crystal lifting and rotating mechanism until the conical ring is immersed 3 mm to 8 mm from the surface of the gallium oxide melt; (5) By controlling nucleation, a high-quality seed crystal is generated at the center of the surface of the gallium oxide melt, and the high-quality seed crystal is controlled to expand stably to form a crystal, and the crystal is further expanded until the crystal contacts the inner wall of the conical ring. (6) After confirming that the crystal is in stable contact with the conical ring by direct observation and the change in the weighing value of the seed crystal lifting and rotating mechanism, the conical ring is lifted by the seed crystal lifting and rotating mechanism at a speed of 0.5 mm / h to 5 mm / h to enter the constant diameter growth control stage. (7) After the crystal grows to a predetermined size, gradually increase the power of the induction heating coil and increase the rising speed of the conical ring to make the crystal end and separate from the gallium oxide melt; (8) After the thermal field cools down, the crystal growth is completed.

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