Equipment and method for growing large-size gallium oxide crystals

Abstract

The invention discloses equipment for growing large-size gallium oxide crystals and a growing method, and relates to the technical field of crystal growing equipment.The equipment comprises a single crystal furnace body, and the single crystal furnace body comprises a seed crystal lifting and rotating mechanism; the heat preservation device can be arranged in the single crystal furnace and comprises a heat preservation container and a heat preservation top plate; the metal crucible can be placed in the heat preservation container; the first driving mechanism is used for driving the metal crucible to rotate; the induction heating coil is sleeved outside the heat preservation container; and the conical surface ring is connected with the output end of the seed crystal lifting and rotating mechanism through a connecting assembly. The growth method comprises the following steps: melting a gallium oxide raw material, descending the conical ring, generating high-quality seed crystals through nucleation control, expanding to a crystal face, lifting the conical ring to perform equal-diameter growth control after the crystal face is in stable contact with the conical ring, and ending after the crystals reach a set size. The twin crystal defect in a traditional guided mode or Czochralski method can be effectively avoided, and crystals with higher quality can be grown.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth equipment, and in particular to an equipment and a growth method for growing large-size gallium oxide crystals. Background Art

[0002] With the continuous development of science and technology, power devices made of wide bandgap semiconductors are increasingly attracting widespread attention as the next generation of 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 great attention because it has a larger bandgap than SiC and GaN, showing a broader application market prospect.

[0003] Among the methods for growing gallium oxide crystals, the dominant ones are the guided mold method, the Czochralski method, and the casting method. However, these methods all have certain limitations. When the guided mold method and the Czochralski method are used to grow large-sized crystals, the (100) crystal plane is very likely to produce twins, resulting in smaller product specifications and greater difficulty in controlling the growth process. In addition, in the guided mold method, due to the presence of the mold, the amount of iridium used is far greater than other methods for growing gallium oxide crystals. Although the casting method grows in a crucible, it is limited by the specifications of the crucible. On the one hand, it is difficult to remove the crystal from the crucible. On the other hand, if the output is to be increased, the required crucible is larger and deeper, and too much iridium raw material is used to prepare the crucible. At present, other methods for growing gallium oxide crystals do not yet have the conditions for industrialization.

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

[0005] The purpose of the present invention is to provide a device and a method for growing large-sized gallium oxide crystals, so as to solve the problems existing in the above-mentioned prior art and improve the efficiency of growing large-sized gallium oxide crystals.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a device for growing large-size gallium oxide crystals, comprising:

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

[0009] A heat preservation device that can be arranged in the single crystal furnace body, the heat preservation device comprising a heat preservation container and a heat preservation top plate used to cover the top of the heat preservation container;

[0010] A metal crucible that can be placed in the thermal insulation container;

[0011] a first driving mechanism, the first driving mechanism is used to drive the metal crucible to rotate; the first driving mechanism comprises 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 in the heat preservation container and is used to support the metal crucible, and the output shaft passes through the single crystal furnace body and the heat preservation container;

[0012] an induction heating coil sleeved outside the heat-insulating container, the induction heating coil being used for induction heating the metal crucible in the heat-insulating container;

[0013] A horizontally arranged conical ring, the material of which is a platinum-rhodium alloy with an iridium or rhodium content of ≥20%, the outer diameter and inner diameter of which gradually decrease from top to bottom, the conical ring being connected to the output end of the seed crystal lifting and rotating mechanism through a connecting component, the seed crystal lifting and rotating mechanism being used to drive the conical ring to rotate and lift, and the seed crystal lifting and rotating mechanism being able to weigh the conical ring; the conical ring being able to 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 through a first connecting wire, and the conical ring is connected to the fixing frame through at least three circumferentially evenly 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 thermal insulation top plate is provided with first through holes corresponding one to one with the second connecting wires, and the second connecting wires pass through the corresponding first through holes.

[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 thermal insulation 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 cone ring is 45° to 75°.

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

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

[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 5 mm to 10 mm.

[0023] The present invention also provides a method for growing large-sized gallium oxide crystals, based on the above-mentioned device for growing large-sized gallium oxide crystals, comprising the following steps:

[0024] (1) placing a heat preservation device in the single crystal furnace body, then placing the gallium oxide raw material in the metal crucible, then placing the metal crucible in a heat preservation container, and then covering the heat preservation container with the heat preservation top plate;

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

[0026] (3) adjusting 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 driving the metal crucible to rotate through the first driving mechanism;

[0027] (4) driving the conical ring to descend by 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) generating a high-quality seed crystal at the center of the melt surface of the gallium oxide melt through nucleation control, controlling the high-quality seed crystal to stably expand to form a crystal, and allowing the crystal to further expand 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 at a speed of 0.5 mm / h to 5 mm / h by the seed crystal lifting and rotating mechanism to enter the equal diameter growth control stage;

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

[0031] (8) After the overall temperature of the heat field has dropped, crystal growth is completed.

[0032] Compared with the prior art, the present invention has achieved the following technical effects:

[0033] The device and method for growing large-size gallium oxide crystals of the present invention combine the advantages of high nucleation quality of the casting method, equal diameter control technology of Czochralski pulling, and low thermal stress of growth outside the crucible, and can effectively avoid twin defects in traditional guided molds or Czochralski methods and grow higher quality crystals.

[0034] Furthermore, the subsequent combination with continuous feeding technology can continue to improve the crystal height, further increase the single furnace production capacity, and provide strong support for the industrialization development of gallium oxide.

[0035] Furthermore, compared with the guided mold method, the present invention reduces the amount of iridium used and lost, and reduces production costs. At the same time, it solves the problems of limited crystal growth thickness, low yield, and difficulty in solving twins in gallium oxide crystals. Compared with the casting method, the present invention avoids the influence of mechanical stress of crucible squeezing on the crystal structure, and solves the problem of difficulty in taking out the crystal from the crucible after growth is completed and the problem that the crystal specifications are greatly affected by the crucible size. Compared with the direct pulling method, it reduces the difficulty of shouldering and reduces the generation of twins.

[0036] Furthermore, the cone ring can be weighed, rotated, and lifted and lowered through the seed crystal lifting and rotating mechanism, thereby achieving accurate monitoring and adjustment of the crystal growth process.

[0037] Furthermore, the quality and stability of crystal growth are ensured through nucleation control and isodiametric growth control.

[0038] Furthermore, the present invention provides two connection assembly options, which can be adjusted according to the actual equipment conditions. One is to connect the conical ring and the seed crystal lifting and rotating mechanism through a fixed frame and multiple connecting wires, and the other is to directly connect the conical ring and the seed crystal lifting and rotating mechanism with a hanging structure composed of inclined wires, thereby increasing the applicability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 Schematic diagram of the structure of the device for growing a long-sized gallium oxide crystal according to an embodiment of the present invention Figure 1 ;

[0041] Figure 2 Schematic diagram of the structure of the device for growing a long-sized gallium oxide crystal according to an embodiment of the present invention Figure 2 ;

[0042] Figure 3Schematic diagram of the structure of the device for growing a long-sized gallium oxide crystal according to an embodiment of the present invention Figure 3 ;

[0043] Figure 4 This is a schematic diagram of the structure of a device for growing large-sized gallium oxide crystals according to the second embodiment of the present invention;

[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 drive 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 DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] The purpose of the present invention is to provide a device and a method for growing large-sized gallium oxide crystals, so as to solve the problems existing in the above-mentioned prior art and improve the efficiency of growing large-sized gallium oxide crystals.

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Embodiment 1

[0049] like Figures 1 to 3 As shown, this embodiment provides a device for growing large-sized gallium oxide crystals, including:

[0050] A single crystal furnace body 1, the single crystal furnace body 1 comprises a seed crystal lifting and rotating mechanism 2;

[0051] A heat preservation device that can be arranged in the single crystal furnace body 1, the heat preservation device comprising 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 in the heat-insulating container 3;

[0053] A first driving mechanism, 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 in the heat preservation container 3 and is used to support the metal crucible 8, and the output shaft passes through the single crystal furnace body 1 and the heat preservation container 3;

[0054] An induction heating coil 4 is sleeved outside the heat preservation container 3, and the induction heating coil 4 is used to induction heat the metal crucible 8 in the heat preservation container 3;

[0055] The conical ring 14 is arranged horizontally, and the material of the conical ring 14 is a platinum-rhodium alloy with an iridium or rhodium content ≥ 20%. The outer diameter and the inner diameter 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 through a connecting component. The seed crystal lifting and rotating mechanism 2 is used to drive the conical ring 14 to rotate and lift, and the seed crystal lifting and rotating mechanism 2 can weigh the conical ring 14; the conical ring 14 can enter the metal crucible 8.

[0056] It is worth noting that the single crystal furnace body 1 and the seed crystal lifting and rotating mechanism 2 with weighing function are both mature equipment, so 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 are not described in detail in this embodiment. The reason why the outer diameter and inner diameter of the conical ring 14 are gradually reduced from top to bottom is that the conical ring 14 can clamp the grown large-sized gallium oxide crystals to ensure that the large-sized gallium oxide crystals will not fall from the conical ring 14.

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

[0058] In an optional solution of the present embodiment, it is more preferred that first through holes corresponding one to one with the second connecting wires 11 are provided on the heat-insulating top plate 5, and the second connecting wires 11 pass through the corresponding first through holes.

[0059] In the optional scheme 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, with the purpose of reducing contact stress.

[0060] In an optional solution of the present embodiment, it is more preferred that an observation port is provided on the heat-insulating top plate 5 , through which the metal crucible 8 and the conical ring 14 can be observed.

[0061] In the optional solution of this embodiment, it is more preferred that the height of the metal crucible 8 is 30 mm to 120 mm.

[0062] Embodiment 2

[0063] like Figure 4As shown, this embodiment provides a device for growing large-sized gallium oxide crystals. The device for growing large-sized gallium oxide crystals in this embodiment is the same as the device for growing large-sized gallium oxide crystals in Example 1 in structure and working principle, and the only difference is that:

[0064] The connecting assembly includes a third connecting wire 12 and at least three circumferentially evenly distributed fourth connecting wires 13. The top of the third connecting wire 12 is connected to the output end of the seed crystal lifting and rotating mechanism 2, the top 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 thermal insulation 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 connection assembly in this embodiment can form a balanced suspension structure, and then be connected to the seed crystal lifting and rotating mechanism 2. This approach can cancel the crucible rotation function, but will increase the force on each third connecting wire 12 and the fourth connecting wire 13, and the risk of damage will increase significantly, so it can be used but not recommended.

[0067] Embodiment 3

[0068] This embodiment provides a method for growing a large-sized gallium oxide crystal, based on the device for growing a large-sized gallium oxide crystal in Embodiment 1 or Embodiment 2, comprising the following steps:

[0069] (1) placing a heat preservation device in the single crystal furnace body 1, then placing the gallium oxide raw material in the metal crucible 8, then placing the metal crucible 8 in the heat preservation container 3, and then covering the heat preservation container 3 with a heat preservation top plate 5;

[0070] (2) turning 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 a gallium oxide melt;

[0071] (3) adjusting 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 driving the metal crucible 8 to rotate through the first driving mechanism;

[0072] (4) driving the conical ring 14 downward through the seed crystal lifting and rotating mechanism 2 until the conical ring 14 is immersed 3 mm to 8 mm 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 melt 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 stably expand 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 the changes in the weighing value of the seed crystal lifting and rotating mechanism 2 (after the crystal face of the crystal is in stable contact with the conical ring 14, the crystal face of the crystal will play a certain supporting role on the conical ring 14, so that the weighing value of the seed crystal lifting and rotating mechanism 2 decreases), it is confirmed that after the crystal face is in stable contact with the conical ring 14 (such as Figure 2 As shown), the cone ring 14 is started to be lifted at a speed of 0.5 mm / h to 5 mm / h by the seed crystal lifting and rotating mechanism 2, and enters the equal diameter growth control stage;

[0075] (7) After the crystal grows to a predetermined size, the power of the induction heating coil 4 is gradually increased and the rising speed of the conical ring 14 is increased to close the crystal and separate it from the gallium oxide melt (e.g. Figure 3 shown);

[0076] (8) After the overall temperature of the heat field has dropped, 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 the invention patent CN114561701A, and will not be elaborated in this embodiment.

[0078] Among the optional schemes of this embodiment, it is more preferred that during the crystal growth process, the crucible height can be reduced to a certain extent and the crystal single furnace output can be further improved by using continuous feeding technology. The continuous feeding technology is a prior art, and the detailed description in patent CN221480153U can be referred to, and it will not be elaborated in this embodiment.

[0079] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A device for growing large-sized gallium oxide crystals, characterized in that: include: A single crystal furnace body, the single crystal furnace body comprising a seed crystal lifting and rotating mechanism; A heat preservation device that can be arranged in the single crystal furnace body, the heat preservation device comprising a heat preservation container and a heat preservation top plate used to cover the top of the heat preservation container; A metal crucible that can be placed in the thermal insulation container; a first driving mechanism, the first driving mechanism is used to drive the metal crucible to rotate; the first driving mechanism comprises 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 in the heat preservation container and is used to support the metal crucible, and the output shaft passes through the single crystal furnace body and the heat preservation container; an induction heating coil sleeved outside the heat-insulating container, the induction heating coil being used for induction heating the metal crucible in the heat-insulating container; A horizontally arranged conical ring, the material of which is a platinum-rhodium alloy with an iridium or rhodium content of ≥20%, the outer diameter and inner diameter of which gradually decrease from top to bottom, the conical ring being connected to the output end of the seed crystal lifting and rotating mechanism through a connecting component, the seed crystal lifting and rotating mechanism being used to drive the conical ring to rotate and lift, and the seed crystal lifting and rotating mechanism being able to weigh the conical ring; the conical ring being able to enter the metal crucible.

2. The device 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 through a first connecting wire, and the conical ring is connected to the fixing frame through at least three circumferentially evenly 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 device for growing large-size gallium oxide crystals according to claim 2, characterized in that: The thermal insulation top plate is provided with first through holes corresponding to the second connecting wires one by one, and the second connecting wires pass through the corresponding first through holes.

4. The device 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 device for growing large-size gallium oxide crystals according to claim 4, characterized in that: 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.

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

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

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

9. A method for growing large-sized gallium oxide crystals, characterized in that: The device for growing large-sized gallium oxide crystals according to any one of claims 1 to 8 comprises the following steps: (1) placing a heat preservation device in the single crystal furnace body, then placing the gallium oxide raw material in the metal crucible, then placing the metal crucible in a heat preservation container, and then covering the heat preservation container with the heat preservation top plate; (2) turning on the induction heating coil to perform induction heating on the metal crucible, so that the gallium oxide raw material in the metal crucible is completely melted to form a gallium oxide melt; (3) adjusting 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 driving the metal crucible to rotate through the first driving mechanism; (4) driving the conical ring to descend by 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) generating a high-quality seed crystal at the center of the melt surface of the gallium oxide melt through nucleation control, controlling the high-quality seed crystal to stably expand to form a crystal, and allowing the crystal to further expand 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 at a speed of 0.5 mm / h to 5 mm / h by the seed crystal lifting and rotating mechanism to enter the equal diameter growth control stage; (7) After the crystal grows to a predetermined size, gradually increasing the power of the induction heating coil and increasing the rising speed of the conical ring to close the crystal and separate it from the gallium oxide melt; (8) After the overall temperature of the heat field has dropped, crystal growth is completed.

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