Preparation method of graphite crucible and tantalum carbide crucible

Abstract

The invention discloses a preparation method of a graphite crucible and a tantalum carbide crucible. The graphite crucible comprises a crucible barrel body and a temperature control assembly arranged in the crucible barrel body, the temperature control assembly comprises a plurality of heat-conducting fins arranged at intervals in the axial direction of the crucible barrel body, and the extension plane of any heat-conducting fin intersects with the axis of the crucible barrel body. When the graphite crucible is applied to preparation of the tantalum carbide crucible, the heat-conducting fins are arranged in the axial direction of the crucible barrel body, so that the axial temperature gradient during carburization of the tantalum carbide crucible can be reduced, the problems of different inner diameters, cracks and the like of the tantalum carbide crucible are avoided, the quality of the tantalum carbide crucible is improved, and the cost of applying the tantalum crucible to a crystal growth process is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal growth, and in particular relates to a method for preparing a graphite crucible and a tantalum carbide crucible. Background Art

[0002] As a wide bandgap III-V semiconductor material, aluminum nitride has many excellent properties. In the field of crystal epitaxial growth, aluminum nitride is an ideal epitaxial substrate material for III-nitrides, which can greatly reduce the lattice mismatch and thermal mismatch caused by growing III-nitrides on substrates such as silicon, sapphire, and silicon carbide.

[0003] In the process of preparing aluminum nitride crystals by physical vapor transport (PVT method), if an induction heating furnace is used to grow aluminum nitride single crystals, a tantalum carbide crucible is generally used as a crystal growth crucible. Tantalum carbide crucibles are mainly made by high-temperature carburizing of pure tantalum crucibles. The common carburizing process is to put a pure tantalum crucible into a graphite crucible, fill it with graphite powder, and heat it up by induction heating to carbonize it, so that the tantalum material becomes a tantalum carbide material with more stable performance.

[0004] The existing carburizing process and crystal growth process share the same induction heating equipment, and the axial temperature gradient of the induction heat field is large. The axial temperature gradient is conducive to the growth of aluminum nitride single crystals, but is not conducive to the preparation of tantalum carbide crucibles, and it is easy to cause problems such as uneven crucible surface, uneven inner diameter of the barrel, and axial cracks after carburizing the tantalum crucible.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a method for preparing a graphite crucible and a tantalum carbide crucible. Summary of the invention

[0006] The object of the present invention is to provide a graphite crucible for optimizing the thermal field of carburizing of a tantalum crucible, which can solve the problem that the size of the tantalum crucible after carburizing does not meet the requirements and axial cracks are easily generated.

[0007] In order to achieve the above object, a specific embodiment of the present invention provides a graphite crucible, and the technical solution is as follows:

[0008] A graphite crucible comprises a crucible barrel body and a temperature control component arranged in the crucible barrel body, wherein the temperature control component comprises a plurality of heat conducting plates arranged at intervals along the axial direction of the crucible barrel body, and an extended plane of any of the heat conducting plates intersects with the axis of the crucible barrel body.

[0009] In one or more embodiments of the present invention, the temperature control assembly further includes a heat conducting rod, which is disposed in the crucible barrel body, and the axial direction of the heat conducting rod is parallel to the axial direction of the crucible barrel body, and the heat conducting sheet is distributed on the outer peripheral wall of the heat conducting rod.

[0010] In one or more embodiments of the present invention, the heat conducting plate is positionally adjustable in the axial direction of the heat conducting rod; and / or, the heat conducting rod is coaxially arranged with the crucible barrel; and / or, a plurality of the heat conducting plates are threadedly connected to the heat conducting rod; and / or, the heat conducting rod is made of graphite.

[0011] In one or more embodiments of the present invention, the crucible barrel includes a hollow cylinder, a cover plate and a bottom plate, the cover plate and the bottom plate are arranged at both ends of the hollow cylinder to form a sealed space, and the heat conducting rod is detachably connected to the bottom plate and / or the cover plate.

[0012] In one or more embodiments of the present invention, the heat conducting rod is threadedly connected to the bottom plate and / or the cover plate.

[0013] In one or more embodiments of the present invention, the plurality of heat conducting plates are evenly distributed along the axial direction of the heat conducting rod; or, the plurality of heat conducting plates are concentratedly distributed within a preset interval in the axial direction of the heat conducting rod.

[0014] In one or more embodiments of the present invention, the plane where the heat conducting sheet is located is perpendicular to the axis of the crucible barrel; and / or the heat conducting sheet is made of graphite.

[0015] In one or more embodiments of the present invention, on a plane perpendicular to the axial direction of the crucible barrel, the edge shape of the vertical projection of the heat conducting plate is arc-shaped, sawtooth-shaped, or wavy.

[0016] A specific embodiment of the present invention also provides a method for preparing a tantalum carbide crucible, and the technical solution is as follows:

[0017] A method for preparing a tantalum carbide crucible, comprising:

[0018] Providing a graphite crucible, a tantalum crucible and carbon powder, wherein the graphite crucible is the above-mentioned graphite crucible;

[0019] Placing the tantalum crucible in the graphite crucible, and sleeve the tantalum crucible outside the heat conducting sheet;

[0020] The graphite crucible is filled with carbon powder, and the tantalum crucible is heated to generate a tantalum carbide crucible.

[0021] In one or more embodiments of the present invention, an induction heating device is used to generate an induction heat field inside the graphite crucible.

[0022] Compared with the prior art, when the graphite crucible of the present invention is used to prepare a tantalum carbide crucible, a heat conducting sheet is arranged along the axial direction of the crucible barrel, so that the axial temperature gradient of the tantalum crucible during carburizing can be reduced, thereby avoiding problems such as uneven inner diameter and cracks of the tantalum carbide crucible, improving the quality of the tantalum carbide crucible, and reducing the cost of the tantalum crucible in the crystal growth process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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 or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A schematic diagram of disassembling a graphite crucible in one embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of a graphite crucible used in a carburizing process in one embodiment of the present invention;

[0026] Figure 3 Schematic diagram of thermal field of different graphite crucible structures in the present invention;

[0027] Figure 4 Schematic diagram of axial temperature gradient of different graphite crucible structures in the present invention;

[0028] Figure 5 Schematic diagram of radial temperature gradient of different graphite crucible structures in the present invention;

[0029] Figure 6 The figure is a flow chart of a method for preparing a tantalum carbide crucible according to an embodiment of the present invention.

[0030] Description of main reference numerals:

[0031] 11. Hollow cylinder; 12. Cover plate; 13. Bottom plate; 21. Heat conducting sheet; 22. Heat conducting rod; 3. Tantalum crucible; 4. Induction heating equipment. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0033] In the prior art, in the process of preparing aluminum nitride crystals by physical vapor transport method, if an induction heating furnace is used to grow aluminum nitride single crystals, a tantalum carbide crucible is generally used as a crystal growth crucible. Tantalum carbide crucibles are mainly prepared by high-temperature carburizing of pure tantalum crucibles, and a graphite crucible is usually required in the carburizing process. When a graphite crucible is used to prepare a tantalum carbide crucible, due to the uneven axial temperature distribution inside the crucible, the tantalum carbide crucible prepared by the carburizing process is prone to cracks along its axial direction and has poor quality. The embodiment of the present invention provides a method for preparing a graphite crucible and a tantalum carbide crucible that can effectively solve the above problems.

[0034] Example 1

[0035] Reference Figure 1 and Figure 2 An embodiment of the present invention provides a graphite crucible, comprising a crucible barrel and a temperature control component disposed in the crucible barrel, wherein the temperature control component comprises a plurality of heat conducting sheets 21 arranged at intervals along the axial direction of the crucible barrel, and the extended plane of any heat conducting sheet 21 intersects with the axis of the crucible barrel. In this embodiment, the heat conducting sheet 21 can be made of graphite material.

[0036] With reference Figure 3 , which intercepted Figure 2 The graphite crucible in the figure shows the temperature distribution inside it. Figure 3 Figure (a) is a schematic diagram of the temperature field in the graphite crucible without a temperature control component; Figure 3 Figure (b) is a schematic diagram of the temperature field of the temperature control component including the heat conducting sheet 21. It should be noted that: Figure 3 The middle line is the isotherm.

[0037] With reference Figure 3 It can be seen from the isotherms in Figures (a) and (b) that the multiple heat conducting sheets 21 arranged along the axial direction of the crucible barrel can optimize the uniformity of the axial temperature gradient of the tantalum crucible 3 during the carburizing process, reduce the temperature difference of the tantalum crucible 3 in its axial direction, and thus avoid axial cracks in the tantalum carbide crucible. Figure 4 It can be seen that only providing the heat conducting sheet 21 can effectively reduce the value of the axial temperature gradient in the graphite crucible, that is, can reduce the axial temperature difference, so as to reduce the possibility of appearance defects when preparing the tantalum carbide crucible.

[0038] Example 2

[0039] Reference Figure 1 and Figure 2On the basis of Example 1, the temperature control assembly in this embodiment further includes a heat conducting rod 22, which is disposed in the crucible barrel, and the axial direction of the heat conducting rod 22 is parallel to the axial direction of the crucible barrel, and the heat conducting sheet 21 is distributed on the outer peripheral wall of the heat conducting rod 22. The heat conducting sheet 21 and the heat conducting rod 22 can be made of graphite.

[0040] Depend on Figure 4 and Figure 5 By comparison, it can be seen that only providing the heat conducting sheet 21 can effectively reduce the axial temperature gradient, but will correspondingly greatly increase the radial temperature gradient. Only providing the heat conducting rod 22 can reduce the axial temperature gradient less effectively than the heat conducting sheet 21, but can greatly improve the stability of the radial temperature gradient.

[0041] In this embodiment, the Figure 3 , Figure 3 Figure (c) is a schematic diagram of the temperature field when the temperature control assembly is only provided with the heat conducting rod 22; Figure 3 Figure (d) is a schematic diagram of the temperature field of the temperature control component including the heat conducting sheet 21 and the heat conducting rod 22. Figure 3 It can be seen that the temperature control assembly including the heat conducting rod 22 and the heat conducting sheet 21 can effectively control the axial temperature gradient without significantly increasing the radial temperature gradient.

[0042] Reference Figure 1 and Figure 2 In this embodiment, the position of the heat conducting sheet 21 in the axial direction of the heat conducting rod 22 is adjustable. Specifically, the plurality of heat conducting sheets 21 are threadedly connected to the heat conducting rod 22. The threaded connection improves the convenience of assembling the heat conducting sheet 21 to the heat conducting rod 22, and can also adjust the positions of the plurality of heat conducting sheets 21. It can be understood that by adjusting the relative positions between the heat conducting sheets 21, the axial temperature can be further controlled and adjusted.

[0043] Furthermore, the plurality of heat conducting sheets 21 are evenly distributed along the axial direction of the heat conducting rod 22; or, the plurality of heat conducting sheets 21 are concentratedly distributed within a preset interval in the axial direction of the heat conducting rod 22. Therefore, the distribution of the heat conducting sheets 21 on the heat conducting rod 22 can be adjusted according to actual production needs to reduce the axial temperature difference in the graphite crucible, so as to ensure the preparation quality of the tantalum carbide crucible.

[0044] Reference Figure 1 and Figure 2The crucible barrel includes a hollow cylinder 11, a cover plate 12 and a bottom plate 13. The cover plate 12 and the bottom plate 13 are covered at both ends of the hollow cylinder 11 to form a sealed space. The heat conducting rod 22 is detachably connected to the bottom plate 13 and / or the cover plate 12. The heat conducting rod 22 is threadedly connected to the bottom plate 13 and / or the cover plate 12. In other embodiments, the heat conducting rod 22 and the bottom plate 13 and / or the cover plate 12 can also be detachably connected in different ways such as plug-in, mortise and tenon connection. Therefore, when the graphite crucible of this embodiment is used in the carburizing process of the tantalum crucible 3, a temperature control component can be set to ensure the production quality of the tantalum carbide crucible; and when it is subsequently used in the crystal growth process, the temperature control component can be removed to ensure the growth of the crystal.

[0045] Reference Figure 2 Furthermore, the heat conducting rod 22 is coaxially arranged with the crucible barrel, and the plane where the heat conducting sheet 21 is located is perpendicular to the axis of the crucible barrel. On the plane perpendicular to the axial direction of the crucible barrel, the edge shape of the vertical projection of the heat conducting sheet 21 is arc-shaped, or sawtooth-shaped, or wavy-shaped, etc., and the present invention does not make specific restrictions on this. The structural design of the heat conducting sheet 21 and the heat conducting rod 22 can further ensure the uniformity of the axial temperature distribution in the graphite crucible.

[0046] The present invention can effectively reduce the axial temperature gradient of the tantalum crucible 3 during the carburizing process by arranging a temperature control component in the crucible barrel, thereby avoiding the problems of inconsistent inner diameter and cracks in the tantalum carbide crucible. Therefore, the present invention can significantly improve the quality of the tantalum carbide crucible and reduce its cost in the crystal growth process.

[0047] Reference Figure 2 and Figure 6 An embodiment of the present invention provides a method for preparing a tantalum carbide crucible, comprising:

[0048] S101, providing a graphite crucible, a tantalum crucible 3 and carbon powder, wherein the graphite crucible is the above-mentioned graphite crucible;

[0049] S102, placing the tantalum crucible 3 in the graphite crucible, and sleeve the tantalum crucible 3 outside the heat conducting sheet 21;

[0050] S103, filling carbon powder into the graphite crucible, and heating the tantalum crucible 3 to generate a tantalum carbide crucible.

[0051] Among them, an induction heating device 4 can be used to generate an induction heat field inside the graphite crucible, and the induction heating device 4 can be an induction heating furnace. In induction heating, the graphite crucible acts as a heat receiving body, generating an induced current with the same frequency and opposite direction as the induction coil. Since the induced current forms a closed loop along the surface of the crucible, it is usually called eddy current. The eddy current is mainly distributed on the surface of the workpiece, and almost no current passes through the inside of the workpiece. This phenomenon is called the skin effect. The skin effect can be used to rapidly heat the surface of the crucible, and then heat the inside of the graphite crucible through heat transfer.

[0052] The heat conducting rod 22 and the heat conducting sheet 21 are different from the surrounding carbon powder in heat conduction and heat radiation capabilities, so the uniformity of the axial temperature inside the graphite crucible can be effectively adjusted, and the axial temperature gradient of the tantalum crucible 3 during carburizing can be reduced, thereby avoiding the problems of uneven inner diameter of the tantalum carbide crucible and cracks, thereby improving the quality of the tantalum carbide crucible.

[0053] The existing carburizing process and crystal growth process share the same induction heating equipment 4, and the axial temperature gradient of the induction heat field is relatively large. The axial temperature gradient is conducive to the growth of aluminum nitride single crystals, but is not conducive to the preparation of tantalum carbide crucibles. Adjusting the original induction heating equipment 4 will inevitably affect the subsequent crystal growth process. And redesigning a new induction heating equipment 4 for the carburizing step will undoubtedly greatly increase the cost. Therefore, the present invention can optimize the axial temperature distribution gradient in the graphite crucible by adjusting the structure of the graphite crucible. Therefore, it can not only ensure the quality of the tantalum carbide crucible prepared in the carburizing process, but also reduce the cost of producing aluminum nitride crystals.

[0054] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0055] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A graphite crucible, characterized in that: The invention comprises a crucible barrel body and a temperature control component arranged in the crucible barrel body, wherein the temperature control component comprises a plurality of heat conducting plates (21) arranged at intervals along the axial direction of the crucible barrel body, and an extended plane of any heat conducting plate (21) intersects with the axis of the crucible barrel body.

2. The graphite crucible according to claim 1, characterized in that: The temperature control assembly further comprises a heat conducting rod (22), the heat conducting rod (22) being arranged in the crucible barrel body, and the axial direction of the heat conducting rod (22) being parallel to the axial direction of the crucible barrel body, and the heat conducting sheet (21) being distributed on the outer peripheral wall of the heat conducting rod (22).

3. The graphite crucible according to claim 2, characterized in that: The heat conducting sheet (21) is positionally adjustable in the axial direction of the heat conducting rod (22); and / or the heat conducting rod (22) is coaxially arranged with the crucible barrel; and / or a plurality of the heat conducting sheets (21) are threadedly connected to the heat conducting rod (22); and / or the heat conducting rod (22) is made of graphite.

4. The graphite crucible according to claim 2, characterized in that: The crucible barrel comprises a hollow cylinder (11), a cover plate (12) and a bottom plate (13); the cover plate (12) and the bottom plate (13) are arranged at both ends of the hollow cylinder (11) to form a sealed space; and the heat conducting rod (22) is detachably connected to the bottom plate (13) and / or the cover plate (12).

5. The graphite crucible according to claim 4, characterized in that: The heat conducting rod (22) is threadedly connected to the base plate (13) and / or the cover plate (12).

6. The graphite crucible according to claim 2, characterized in that: The plurality of heat-conducting sheets (21) are evenly distributed along the axial direction of the heat-conducting rod (22); or the plurality of heat-conducting sheets (21) are concentratedly distributed within a preset interval in the axial direction of the heat-conducting rod (22).

7. The graphite crucible according to claim 1, characterized in that: The plane where the heat conducting plate (21) is located is arranged perpendicular to the axis of the crucible barrel; and / or the heat conducting plate (21) is made of graphite.

8. The graphite crucible according to claim 1, characterized in that: On a plane perpendicular to the axial direction of the crucible barrel, the edge shape of the vertical projection of the heat conducting sheet (21) is arc-shaped, sawtooth-shaped, or wavy.

9. A method for preparing a tantalum carbide crucible, characterized in that: include: Providing a graphite crucible, a tantalum crucible (3) and carbon powder, wherein the graphite crucible is the graphite crucible according to any one of claims 1 to 8; The tantalum crucible (3) is placed in the graphite crucible, and the tantalum crucible (3) is sleeved outside the heat conducting sheet (21); Carbon powder is filled into the graphite crucible, and the tantalum crucible (3) is heated to generate a tantalum carbide crucible.

10. The method for preparing a tantalum carbide crucible according to claim 9, characterized in that: An induction heating device (4) is used to generate an induction heat field inside the graphite crucible.

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