Gallium oxide crystal growing device

Abstract

The present invention relates to the technical field of crystal growth, and discloses a gallium oxide crystal growth apparatus, which comprises: a thermal insulation cylinder, which comprises a cylinder cavity; the crucible is contained at the bottom of the barrel cavity, and the crucible is used for containing gallium oxide raw material powder; the lifting assembly is configured to extend into the barrel cavity and is used for lifting the gallium oxide crystal; the reflecting screen assembly is arranged in the barrel cavity and is arranged on the periphery of the barrel cavity; and the lifting assembly is configured to enable the reflecting screen assembly to ascend and descend in the direction from the bottom of the barrel cavity to the top of the barrel cavity. The growth device has the beneficial effects that the temperature distribution in the growth device can be adjusted according to the growth process of gallium oxide, and the influence on crystal growth due to large temperature difference at the solid-liquid level of the crystal in the crystal growth process is avoided.

Description

Technical Field

[0001] This invention relates to the field of crystal growth technology, and in particular to a gallium oxide crystal growth apparatus. Background Technology

[0002] Gallium oxide (GaO) crystals are typically grown using the Czochralski method, where a pulling assembly is used to pull the molten material from the surface of a crucible to obtain the crystal. However, due to the large axial temperature gradient in the early stages of growth, GaO crystals experience severe thermal stress, making them prone to cracking and preventing the production of larger cylindrical crystals. Furthermore, current methods generally use crucibles heated by medium-frequency induction heating as the heating element for GaO crystal growth. Since the crucible cannot completely enclose the entire GaO crystal, the temperature difference between the crystal above the crucible and the solid-liquid interface is too large, which is detrimental to GaO crystal growth. Moreover, the thermal field structure is generally fixed during GaO growth, making it impossible to alter the temperature distribution throughout the growth process. Summary of the Invention

[0003] The purpose of this invention is to provide a gallium oxide crystal growth apparatus that can adjust the temperature distribution within the growth apparatus according to the gallium oxide growth process, thereby avoiding a large temperature difference at the solid-liquid interface of the crystal during crystal growth, which would affect crystal growth.

[0004] To achieve the above objectives, the present invention provides a gallium oxide crystal growth apparatus, comprising:

[0005] Insulation cylinder, the insulation cylinder including a cylindrical cavity;

[0006] A crucible, which is housed at the bottom of the cylindrical cavity, is used to hold gallium oxide raw material powder;

[0007] A lifting assembly configured to extend into the cylindrical cavity and used for lifting gallium oxide crystals;

[0008] A reflective screen assembly is disposed within the cylindrical cavity and around the periphery of the cylindrical cavity;

[0009] A lifting assembly configured to move the reflector assembly up and down in the direction from the bottom of the cavity to the top of the cavity.

[0010] Compared with the prior art, the gallium oxide crystal growth apparatus of the present invention has the following advantages: the reflective screen assembly is arranged around the periphery of the cylinder cavity to reflect heat energy, and the lifting assembly is configured to lift the reflective screen assembly in the direction from the bottom to the top of the cylinder cavity. According to the growth process of the gallium oxide crystal, the heat energy reflection situation in the cylinder cavity can be changed, thereby changing the temperature distribution in the cylinder cavity, reducing the temperature difference at the solid-liquid interface of the crystal, reducing the temperature gradient along the crystal growth axis, avoiding crystal rod cracking, and improving the stability during crystal growth. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the gallium oxide crystal growth apparatus according to an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of the structural principle of another operating condition of the gallium oxide crystal growth apparatus according to an embodiment of the present invention;

[0013] Figure 3 This is a schematic diagram of the structure of the reflective screen assembly of the gallium oxide crystal growth apparatus according to an embodiment of the present invention;

[0014] Figure 4 This is a structural schematic diagram of another working condition of the reflective screen assembly of the gallium oxide crystal growth apparatus in an embodiment of the present invention.

[0015] In the picture,

[0016] 1. Insulation cylinder; 11. Cylinder cavity;

[0017] 2. Crucible;

[0018] 3. Lifting assembly;

[0019] 4. Reflective screen assembly; 41. First reflective screen; 411. First sub-screen; 412. Second sub-screen; 413. Third sub-screen; 42. Second reflective screen; 43. First slide rail; 44. Second slide rail; 45. Linkage rod;

[0020] 5. Lifting assembly; 51. Powered lifting device; 52. Drive device;

[0021] 6. Gap. Detailed Implementation

[0022] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "inner," and "outer," etc., used in this invention to indicate orientation or positional relationships are based on the positional relationships shown in the accompanying drawings and are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device and element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] In the description of this invention, it should be understood that the terms "first," "second," etc., are used to describe various types of information, but these terms are not limited to them; they are only used to distinguish information of the same type from one another. For example, without departing from the scope of this invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0025] like Figure 1 As shown, a gallium oxide crystal growth apparatus according to some embodiments of the present invention includes a heat-insulating cylinder 1, a crucible 2, a lifting assembly 3, a reflective screen assembly 4, and a lifting assembly 5. The heat-insulating cylinder 1 has a cavity 11 inside, and the crucible 2 is housed at the bottom of the cavity 11. The crucible 2 is used to hold gallium oxide raw material powder. An induction coil is provided on the outside of the heat-insulating cylinder 1 for heating and melting the gallium oxide powder in the crucible 2. The lifting assembly 3 is located above the crucible 2 and is configured to extend into the cavity 11 and be used to lift the gallium oxide crystal. That is, the output end of the lifting assembly 3 extends into the cavity 11 and contacts the molten surface inside the crucible 2 to lift and form a gallium oxide crystal. The reflector assembly 4 is disposed inside the cylindrical cavity 11 and around the periphery of the cylindrical cavity 11 to reflect the heat emitted by the crucible 2 and the crystal. The lifting assembly 5 is configured to lift the reflector assembly 4 in the direction from the bottom to the top of the cylindrical cavity 11. By adjusting the position of the reflector assembly 4 from the bottom to the top of the cylindrical cavity 11, the heat reflection situation inside the cylindrical cavity 11 is changed, and the temperature distribution inside the cylindrical cavity 11 is changed.

[0026] The crystal growth process mainly consists of three stages: seed crystal formation, shoulder formation, and constant diameter growth. Seed crystal formation primarily involves the contact between the output end (seed crystal) of the pulling component 3 and the melt, causing the melt to solidify and crystallize on the seed crystal surface. Shoulder formation occurs during the heating and pulling process, where the seed crystal gradually grows. Then, by maintaining a suitable temperature and pulling speed, the crystal diameter remains constant (constant diameter growth stage).

[0027] In some embodiments, for ease of design, the reflective screen assembly 4 includes a first reflective screen 41 and a second reflective screen 42. Specifically, see [reference needed]. Figure 1 , Figure 2The first reflector 41 is close to the periphery of the cylinder cavity 11 and extends in the direction between the bottom and top of the cylinder cavity 11. The end of the first reflector 41 away from the lifting component 3 is connected to the lifting component 5. One end of the second reflector 42 is movably connected to the end of the first reflector 41 close to the lifting component 3. The other end of the second reflector 42 extends in the direction away from the periphery of the cylinder cavity 11 and is fixedly connected to the cylinder wall of the heat preservation cylinder 1.

[0028] In some embodiments, see Figure 3 , Figure 4 The reflective screen assembly 4 also includes a first slide rail 43 disposed on the first reflective screen 41, a second slide rail 44 disposed on the second reflective screen 42, and a connecting rod 45. One end of the connecting rod 45 is connected to the first slide rail 43, and the other end of the connecting rod 45 is connected to the second slide rail 44. An extension line is drawn along the direction away from the bottom of the cylinder cavity 11 of the first reflective screen 41, and the angle between the extension line and the second reflective screen is α. The connecting rod 45 is configured such that as the first reflective screen 41 moves from the bottom to the top of the cylinder cavity 11, the angle α can gradually increase. During crystal growth, by adjusting the pulling speed of the crystal by the pulling assembly 3 and simultaneously adjusting the angle α, the reflected thermal energy can be adjusted synchronously, allowing the crystal to remain stable in each growth process.

[0029] To facilitate the synchronous lifting and lowering of the first reflective screen 41 and the second reflective screen 42, a gap 6 is provided between the crucible 2 and the insulation cylinder 1. The lifting assembly 5 includes a power lifting device 51, the output end of which is connected to the first reflective screen 41. The power lifting device drives the first reflective screen 41 to rise and fall within the gap 6 from the bottom to the top of the cylinder cavity 11. The lifting assembly 5 also includes a drive device 52, which is mounted on the power lifting device. The output end of the drive device 52 and the connecting rod 45 are connected to one end of the first slide rail 43. The drive device 52 can drive the connecting rod 45 to rotate, thereby adjusting the included angle α, so that the connection angle between the first reflective screen 41 and the second reflective screen 42 changes. While the first reflective screen 41 and the second reflective screen 42 rise and fall synchronously, the connection angle changes synchronously, thereby adapting to the growth of the crystal in various growth processes. In order to precisely control the thermal reflection within the cavity 11 as the first reflective screen 41 moves during each growth process, in some embodiments, the first reflective screen 41 is configured to gradually enhance its thermal reflectivity along the direction closer to the lifting assembly 3.

[0030] In order to synchronize the crystal lifting process with the lifting of the reflector assembly 4, in some embodiments, the lifting assembly 5 is configured to control the output end of the lifting assembly 5 to move up and down in the direction from the bottom of the cavity 11 to the top of the cavity 11 based on the lifting of the gallium oxide crystal by the lifting assembly 3.

[0031] To facilitate the design of the structures of the first reflective screen 41 and the second reflective screen 42, the materials of the first reflective screen 41 and the second reflective screen 42 include molybdenum. Specifically, the purity of Mo is ≥99.95%, and the density is ≥10.1 g / cm³, making it suitable for high-temperature environments below 2800°C. In some other embodiments, molybdenum can also be replaced by tungsten, specifically, the purity of W is ≥99.95%, and the density is ≥19.1 g / cm³.

[0032] In some embodiments, in order to make the heat energy more uniform throughout the cavity 11, the first reflective screen 41 is configured to surround the periphery of the inner side of the cavity 11.

[0033] In some embodiments, the first reflective screen 41 is made of molybdenum rings. In the direction from the bottom to the top of the cylindrical cavity 11, the first reflective screen 41 is composed of several sub-screens, each sub-screen including several molybdenum rings. These molybdenum rings are arranged circumferentially along the inner side of the cylindrical cavity 11 and enclose to form a ring. The molybdenum rings and the crucible 2 are coaxially arranged. In some embodiments, the molybdenum rings have the same thickness in the radial direction of the cylindrical cavity 11. Since the first reflective screen 41 is configured to gradually increase its heat reflectivity along the direction closer to the lifting assembly 3, in the direction from the bottom to the top of the cylindrical cavity 11, the number of molybdenum rings in the sub-screen closer to the bottom of the cylindrical cavity 11 is less than the number of molybdenum rings in the sub-screen farther from the bottom of the cylindrical cavity 11. That is, in the vertical direction, the number of molybdenum rings in each sub-screen decreases. To facilitate the connection of the molybdenum rings, adjacent molybdenum rings are bonded in the radial direction of the cylindrical cavity 11, and the bonding material is an insulating material, such as insulating adhesive. To facilitate the design of the molybdenum ring structure, in some embodiments, the cross-sectional shape of the molybdenum ring on the horizontal plane along the radial direction is a circular ring or a regular polygonal ring.

[0034] In some other embodiments, the material of the first reflective screen 41 includes molybdenum sheets. Similarly, in the direction from the bottom to the top of the cylindrical cavity 11, the first reflective screen 41 is composed of several sub-screens. Each sub-screen includes several layers of splicing rings formed by splicing molybdenum sheets around the periphery of the cylindrical cavity 11. Each sub-screen includes several splicing rings, which are arranged radially along the cylindrical cavity 11. In the radial direction of the cylindrical cavity 11, the thickness of the molybdenum sheets is the same. In the direction from the bottom to the top of the cylindrical cavity 11, between two adjacent sub-screens, the number of splicing rings in the sub-screen closer to the bottom of the cylindrical cavity 11 is less than the number of splicing rings in the sub-screen farther from the bottom of the cylindrical cavity 11. Several molybdenum sheets are bonded around the periphery of the cylindrical cavity 11 to form splicing rings; in the radial direction of the cylindrical cavity 11, adjacent splicing rings are bonded; wherein, the bonding material is a heat-insulating material, such as heat-insulating adhesive.

[0035] In some embodiments, the first reflective screen 41 is composed of three sub-screens. Specifically, in the direction from the bottom to the top of the cylindrical cavity 11, due to the different length specifications of different crystals and the heat reflection requirements corresponding to different growth stages of the crystals, the height of each sub-screen needs to be set. The height of the first sub-screen 411 near the bottom of the cylindrical cavity 11 is l1, the height of the third sub-screen 413 away from the bottom of the cylindrical cavity 11 is l3, and the height of the second sub-screen 412 located between the first sub-screen 411 and the third sub-screen 413 is l2, where l3:l2:l1 = (1:1.11:1.3) to (1:1.14:1.45). Preferably, in some embodiments, the length l1 of the first sub-screen 411 is 45mm-65mm, the length l2 of the second sub-screen 412 is 40mm-50mm, and the length l3 of the third sub-screen 413 is 35mm-45mm, corresponding to a total crystal length of 120mm-160mm.

[0036] Specifically, in some embodiments, the first reflective screen 41 is composed of three sub-screens. Referring to the direction from the bottom to the top of the cylindrical cavity 11... Figure 3 , Figure 4 The crystal growth process is explained in conjunction with the structure of the first reflective screen 41 and the included angle α. During crystal growth, the included angle α ranges from 20° to 90°. The changes in the included angle α are explained in conjunction with the specific growth stages of the crystal. During the shoulder formation process, the volatilized gallium oxide will re-condense on the first reflective screen 41, the second reflective screen 42, and the crystal surface. In severe cases, it can condense into needle-like or plate-like impurities. These impurities falling to the solid-liquid interface can easily disrupt the solid-liquid interface balance, leading to polycrystalline formation and crystal cracking, thus affecting crystal quality. Therefore, at this stage, the included angle α is relatively small, ranging from 20° to 30°. The height of the first reflective screen 41 in the vertical direction can be adjusted using the lifting component 5 according to the actual crystal growth requirements, and the included angle α can be adjusted to change the direction of heat reflection, thereby adjusting the temperature distribution inside the cavity 11.

[0037] Meanwhile, during this process, since the included angle α is small, the heat loss inside the cylinder cavity 11 should be avoided from being too fast. That is, the temperature at the solid-liquid interface needs to be kept stable. At this time, the solid-liquid interface corresponds to the third sub-screen 413, which has a good heat preservation and heat reflection effect.

[0038] When a crystal enters the initial stage of constant-diameter growth, it has reached the target diameter and begins constant-diameter growth, at which point the impact of impurity crystal shedding on crystal shoulder formation need not be considered. Furthermore, as the crystal length increases, the temperature difference between the crystal and the solid-liquid interface increases, leading to a greater axial temperature gradient and causing cracking in the gallium oxide crystal. Therefore, it is necessary to reduce the axial temperature gradient. At this point, refer to... Figure 2The lifting component 5 drives the first reflective screen 41 to rise further, so that the solid-liquid interface corresponds to the second sub-screen 412. As the thermal reflection of the sub-screen gradually increases from bottom to top, the included angle α increases, which is in the range of 40°-60°, thereby reducing the axial temperature gradient of the crystal and suppressing crystal rod cracking.

[0039] During the later stages of constant diameter growth, as the length of the crystal increases, the surface area of ​​the crystal also increases, and heat dissipation from the crystal surface accelerates. At this time, in order to avoid heat loss, the preset angle α is increased to a range of 60°-90°, so that the heat is concentrated in the cavity 11. At the same time, in order to reduce the axial temperature gradient of the crystal, the lifting component 5 drives the first reflective screen 41 to rise, so that the solid-liquid interface corresponds to the first sub-screen 411, making the crystal growth process more stable.

[0040] In some embodiments, the lifting device can drive the first reflective screen 41421 to rise at a certain rate, while controlling the speed at which the lifting component 3 lifts the crystal, thereby adjusting the heat reflection effect of the first reflective screen 41 and the second reflective screen 42 to meet the temperature distribution requirements of different crystal growth stages. After the crystal growth is completed, the lifting component 5 drives the first reflective screen 41 to descend, and by changing the included angle α, the crystal can be taken out, thus completing the growth of a single crystal.

[0041] In summary, this embodiment of the invention provides a gallium oxide crystal growth apparatus. The reflective screen assembly 4 is disposed around the periphery of the cylindrical cavity 11 for reflecting heat energy. The lifting assembly 5 is configured to lift the reflective screen assembly 4 in the direction from the bottom to the top of the cylindrical cavity 11. According to the growth process of the gallium oxide crystal, the heat energy reflection situation in the cylindrical cavity 11 can be changed, thereby changing the temperature distribution in the cylindrical cavity 11, reducing the temperature difference at the solid-liquid interface of the crystal, reducing the temperature gradient along the crystal growth axis, avoiding crystal rod cracking, and improving the stability during crystal growth.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A gallium oxide crystal growth apparatus, characterized in that: include: Insulation cylinder, the insulation cylinder including a cylindrical cavity; A crucible, which is housed at the bottom of the cylindrical cavity, is used to hold gallium oxide raw material powder; A lifting assembly configured to extend into the cylindrical cavity and used for lifting gallium oxide crystals; A reflective screen assembly is disposed within the cylindrical cavity and around the periphery of the cylindrical cavity; A lifting assembly configured to move the reflector assembly up and down in the direction from the bottom of the cavity to the top of the cavity.

2. The gallium oxide crystal growth apparatus as described in claim 1, characterized in that: The reflective screen assembly includes a first reflective screen and a second reflective screen. The first reflective screen is close to the periphery of the cylinder cavity and extends in the direction between the bottom and top of the cylinder cavity. The end of the first reflective screen away from the lifting assembly is connected to the lifting assembly. One end of the second reflective screen is movably connected to the end of the first reflective screen close to the lifting assembly. The other end of the second reflective screen extends in the direction away from the periphery of the cylinder cavity and is fixedly connected to the cylinder wall of the insulation cylinder.

3. The gallium oxide crystal growth apparatus as described in claim 2, characterized in that: There is a gap between the crucible and the insulation cylinder. The lifting assembly includes a power lifting device. The output end of the power lifting device is configured to be connected to the first reflective screen. The power lifting device drives the first reflective screen to move up and down within the gap from the bottom of the cylinder cavity to the top of the cylinder cavity.

4. The gallium oxide crystal growth apparatus as described in claim 3, characterized in that: The lifting assembly is configured to control the output end of the lifting assembly to move up and down in the direction from the bottom of the cavity to the top of the cavity based on the lifting assembly's lifting of the gallium oxide crystal.

5. The gallium oxide crystal growth apparatus as described in claim 2, characterized in that: The reflective screen assembly also includes a first slide rail disposed on the first reflective screen, a second slide rail disposed on the second reflective screen, and a connecting rod. One end of the connecting rod is connected to the first slide rail, and the other end of the connecting rod is connected to the second slide rail. An extension line is drawn along the direction of the first reflective screen away from the bottom of the cylinder cavity. The angle between the extension line and the second reflective screen is α. The connecting rod is configured such that as the first reflective screen moves from the bottom of the cylinder cavity to the top of the cylinder cavity, the angle α gradually increases.

6. The gallium oxide crystal growth apparatus as described in claim 4, characterized in that: Along the direction close to the lifting component, the first reflective screen is configured to gradually increase its heat reflectivity.

7. The gallium oxide crystal growth apparatus as described in claim 3, characterized in that: The material of the first reflective screen includes molybdenum.

8. The gallium oxide crystal growth apparatus as described in claim 6, characterized in that: The first reflective screen is configured to surround the periphery of the inner side of the cylindrical cavity.

9. The gallium oxide crystal growth apparatus as described in claim 8, characterized in that: The material of the first reflective screen includes molybdenum rings. In the direction from the bottom of the cylinder to the top of the cylinder, the first reflective screen is composed of several sub-screens, each sub-screen including several molybdenum rings, which are arranged circumferentially along the inner side of the cylinder.

10. The gallium oxide crystal growth apparatus as described in claim 9, characterized in that: In the radial direction of the cavity, the molybdenum rings have the same thickness. In the direction from the bottom to the top of the cavity, between two adjacent sub-screens, the number of molybdenum rings in the sub-screen closer to the bottom of the cavity is less than the number of molybdenum rings in the sub-screen farther from the bottom of the cavity.

11. The gallium oxide crystal growth apparatus as described in claim 8, characterized in that: The first reflective screen is made of molybdenum sheets. In the direction from the bottom to the top of the cylindrical cavity, the first reflective screen is composed of several sub-screens. Each sub-screen includes several layers of splicing rings formed by splicing the molybdenum sheets around the periphery of the cylindrical cavity. Each sub-screen includes several splicing rings, which are arranged radially along the cylindrical cavity.

12. The gallium oxide crystal growth apparatus as described in claim 11, characterized in that: In the radial direction of the cavity, the molybdenum sheets have the same thickness. In the direction from the bottom to the top of the cavity, between two adjacent sub-screens, the number of splicing rings in the sub-screen closer to the bottom of the cavity is less than the number of splicing rings in the sub-screen farther from the bottom of the cavity.

13. The gallium oxide crystal growth apparatus as described in claim 9, characterized in that: In the radial direction of the cylinder cavity, adjacent molybdenum rings are bonded together with a heat-insulating material.

14. The gallium oxide crystal growth apparatus as described in claim 11, characterized in that: Several segments of the molybdenum sheet are bonded together around the periphery of the cylindrical cavity to form the splicing ring; In the radial direction of the cylindrical cavity, adjacent splicing rings are bonded together; The adhesive material is a heat-insulating material.

15. The gallium oxide crystal growth apparatus according to any one of claims 8 to 14, characterized in that: The first reflective screen is composed of three sub-screens.

16. The gallium oxide crystal growth apparatus as described in claim 15, characterized in that: In the direction from the bottom of the cylinder to the top of the cylinder, the height of the first sub-screen near the bottom of the cylinder is l1, the height of the third sub-screen away from the bottom of the cylinder is l3, and the height of the second sub-screen located between the first sub-screen and the third sub-screen is l2, wherein l3:l2:l1 = (1:1.11:1.3) to (1:1.14:1.45).

17. The gallium oxide crystal growth apparatus as described in claim 9, characterized in that: The cross-sectional shape of the molybdenum ring on the horizontal plane arranged radially is a circular ring or a regular polygonal ring.

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