Growth apparatus and growth system for aln crystals
By using a mask to set multiple through holes in the AlN crystal growth apparatus, the gaseous molecules of the raw material are prevented from crystallizing in the areas without through holes, and AlN crystals are promoted to crystallize and expand laterally within the through holes. This solves the problem of poor crystallization quality of AlN crystals and achieves AlN crystal growth with low defect density.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU INST OF ADVANCED SEMICON CO LTD
- Filing Date
- 2025-08-28
- Publication Date
- 2026-07-21
AI Technical Summary
The poor crystal quality and high defect density of AlN crystals in the prior art are mainly due to the continuation of defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations in AlN seed crystals into the crystal.
An AlN crystal growth apparatus is used, including a crucible, a high-temperature resistant fixture, and a mask. The mask has multiple through holes on one side of the AlN seed crystal to prevent the raw material gas molecules from crystallizing in the area without through holes, promote the crystallization of AlN crystals in the through holes and their lateral expansion, and cut off the continuation of defects in the seed crystal.
This improved the crystal quality of AlN crystals, reduced the defect density, and resulted in AlN crystals with low defect density.
Smart Images
Figure CN224531118U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of crystal growth, and in particular to an AlN crystal growth apparatus and growth system. Background Technology
[0002] Aluminum nitride (AlN) is widely used in optoelectronics and microelectronics. Currently, the main method for growing bulk AlN crystals is physical vapor transport (PVT). Its basic principle is as follows: AlN powder is placed below the crucible, sublimates into gaseous molecules (Al and N2), and then transports to the upper part of the crucible. Due to the relatively low temperature at the top of the crucible, the gaseous molecules recrystallize on the substrate or AlN seed crystal.
[0003] However, there are also many technical difficulties in preparing AlN crystals using the PVT method. For example, the growth of crystals is heavily dependent on the crystallization quality of the AlN seed crystal. Defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations in the AlN seed crystal will continue into the crystal, resulting in the grown crystal being inferior to the quality of the AlN seed crystal. Utility Model Content
[0004] The purpose of this invention is to provide an AlN crystal growth device and system to solve the problems of poor crystallization quality and low defect density of AlN crystals in the prior art.
[0005] The objective of this utility model is achieved through the following technical solution:
[0006] This invention provides an AlN crystal growth apparatus, comprising:
[0007] A crucible, the interior of which forms a growth space, the growth space including a raw material placement area near the bottom of the crucible and a crystal growth area near the top of the crucible, the raw material placement area and the crystal growth area being arranged longitudinally along the growth space;
[0008] A high-temperature resistant fastener is disposed in the crystal growth region for fixing an AlN seed crystal; wherein the AlN seed crystal is located on the side of the high-temperature resistant fastener facing the raw material placement area;
[0009] A mask sheet is disposed on the side of the AlN seed crystal away from the high-temperature resistant fixing component, and the mask sheet is provided with multiple through holes;
[0010] The AlN crystal includes a first sub-crystal located within each of the through-holes and a second sub-crystal connected to all the first sub-crystals. The mask is used to prevent the raw material gas molecules from crystallizing in the area of the mask where the through-holes are not provided during the growth of the AlN crystal.
[0011] As a further improvement of one embodiment of the present invention, the thickness of the mask sheet is 0.2mm-0.6mm.
[0012] As a further improvement of one embodiment of the present invention, the plurality of through holes are evenly arranged on the mask sheet, and the spacing between two adjacent through holes is 1mm-5mm;
[0013] And / or, the diameter of the through hole is 1mm-10mm;
[0014] And / or, the mask is a tungsten sheet.
[0015] As a further improvement of one embodiment of this utility model, the thickness of the high-temperature resistant fastener is 1mm or more;
[0016] And / or, the high-temperature resistant fastener is a tungsten sheet;
[0017] And / or, the melting point of the high-temperature resistant fastener is higher than the growth temperature of the AlN crystal, which is used to suppress the volatilization of the AlN seed crystal during the growth of the AlN crystal.
[0018] As a further improvement of one embodiment of the present invention, the surface area of the mask and the surface area of the high-temperature resistant fastener are both greater than the surface area of the AlN seed crystal. When the AlN seed crystal is placed between the mask and the high-temperature resistant fastener, the projection of the mask on the bottom surface of the crucible and the projection of the high-temperature resistant fastener on the bottom surface of the crucible completely cover the projection of the AlN seed crystal on the bottom surface of the crucible.
[0019] As a further improvement of one embodiment of this utility model, both the mask and the high-temperature resistant fastener are cylindrical structures;
[0020] And / or, the through hole is a cylindrical structure, a cubic structure, or a polyhedral structure.
[0021] As a further improvement of one embodiment of the present invention, a stepped structure is provided on the side wall of the crucible. The stepped structure is used to support the peripheral area of the mask sheet to fix the mask sheet and the crucible.
[0022] And / or, the crucible includes a crucible body having the growth space and a crucible lid covering the top of the crucible body.
[0023] This utility model also provides an AlN crystal growth system, including a growth furnace and an AlN crystal growth apparatus as described above, wherein the growth apparatus is placed inside the growth furnace;
[0024] The raw material placement area is used to place AlN raw materials.
[0025] As a further improvement of one embodiment of the present invention, the growth system further includes a first temperature measuring device, a second temperature measuring device, and a heating device disposed in the growth furnace.
[0026] The first temperature measuring device is positioned above the top of the crucible to obtain the temperature at the top of the crucible.
[0027] The second temperature measuring device is located below the bottom of the crucible and is used to obtain the temperature of the bottom of the crucible;
[0028] The heating device is arranged around the crucible and is used to heat the growth space inside the crucible.
[0029] As a further improvement of one embodiment of the present invention, the growth system further includes a vacuum pumping device and a pressure boosting device connected to the growth furnace. The vacuum pumping device is used to make the space inside the growth furnace and the growth device a vacuum state, and the pressure boosting device is used to make the pressure inside the growth furnace and the growth device a preset pressure.
[0030] Compared with the prior art, the beneficial effects of this utility model include at least the following: The AlN crystal growth apparatus provided by this utility model includes a crucible, a high-temperature resistant fixing component disposed within the crucible, and a mask; a growth space is formed inside the crucible, the growth space including a raw material placement area near the bottom of the crucible and a crystal growth area near the top of the crucible, the raw material placement area and the crystal growth area being longitudinally spaced along the growth space; the high-temperature resistant fixing component is disposed in the crystal growth area for fixing the AlN seed crystal, and the AlN seed crystal is located on the side of the high-temperature resistant fixing component facing the raw material placement area; the mask is disposed on the side of the AlN seed crystal away from the high-temperature resistant fixing component, and the mask has multiple through holes; wherein, the AlN crystal includes a first sub-crystal disposed in each through hole and a second sub-crystal connected to all the first sub-crystals, and the mask is used to prevent the raw material gas molecules from crystallizing in the area of the mask without through holes during the growth of the AlN crystal. The growth apparatus provided by this invention has a mask with multiple through holes on one side of the crystallization surface of an AlN seed crystal. The mask is attached to the AlN seed crystal and is used to prevent the gaseous molecules of the raw material from crystallizing in the area of the mask without through holes during the growth of the AlN crystal. In other words, during the growth of the AlN crystal, the gaseous molecules of the raw material preferentially crystallize on the AlN seed crystal located in the through holes. When the through holes are filled with AlN crystals (i.e., the first daughter crystal), the AlN crystals begin to extend out of the through holes and grow laterally along the lower surface of the mask where there are no through holes, merging into a complete AlN crystal (i.e., the second daughter crystal). The laterally growing AlN crystal (the second daughter crystal) interrupts the continuation of defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations in the AlN seed crystal, thereby improving the crystallization quality of the AlN crystal and obtaining an AlN crystal with low defect density. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the structure of an AlN crystal growth apparatus according to one embodiment of the present invention;
[0032] Figure 2 yes Figure 1 A schematic diagram of the cross-section along the AA' direction;
[0033] Figure 3 This is a schematic diagram of the structure of an AlN crystal growth apparatus according to another embodiment of the present invention;
[0034] Figure 4 This is a top view of a crucible body according to one embodiment of the present invention (showing the stepped structure);
[0035] Figure 5 This is a schematic diagram of the structure of a mask sheet according to one embodiment of the present invention;
[0036] Figure 6This is a schematic diagram of the structure of an AlN crystal after growth in one embodiment of this utility model.
[0037] In the diagram: 1. Crucible; 11. Growth space; 111. Raw material placement area; 112. Crystal growth area; 12. Bottom of crucible; 13. Top of crucible; 14. Step structure; 15. Crucible body; 16. Crucible lid; 2. High-temperature resistant fixing component; 3. Mask; 31. Through hole; 4. AlN seed crystal; 51. First sub-crystal; 52. Second sub-crystal; 6. AlN raw material. Detailed Implementation
[0038] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.
[0039] The terms used to describe position and direction in this utility model are illustrated with the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this utility model.
[0040] like Figures 1-5 As shown, this utility model provides an AlN crystal growth apparatus, including a crucible 1, a high-temperature resistant fixing component 2, and a mask 3, wherein the high-temperature resistant fixing component 2 and the mask 3 are disposed inside the crucible 1.
[0041] See Figure 1 and Figure 2 A growth space 11 is formed inside the crucible 1. The growth space 11 includes a raw material placement area 111 near the bottom 12 of the crucible and a crystal growth area 112 near the top 13 of the crucible. The raw material placement area 111 is used to place the growth raw material for AlN crystal, namely AlN raw material 6. The crystal growth area 112 is located above the raw material placement area 111 and is used to place the high-temperature resistant fixing component 2, the mask 3, and the AlN seed crystal 4. The crystallization process of AlN crystal takes place within the crystal growth area 112.
[0042] Specifically, the raw material placement area 111 and the crystal growth area 112 are arranged longitudinally along the growth space 11. That is to say, there is a certain distance between the AlN raw material 6 placed in the raw material placement area 111 and the crystal growth area 112. This distance is the activity range of the raw material gas molecules during the AlN crystal growth process.
[0043] The high-temperature resistant fastener 2 is disposed in the crystal growth area 112 and is used to fix the AlN seed crystal 4. The AlN seed crystal 4 is located on the side of the high-temperature resistant fastener 2 facing the raw material placement area 111, and the AlN seed crystal 4 is specifically fixed to the side of the high-temperature resistant fastener 2 facing the raw material placement area 111 and is attached to and connected to the side of the high-temperature resistant fastener 2 facing the raw material placement area 111.
[0044] Specifically, the high-temperature resistant fastener 2 has a melting point higher than the growth temperature of AlN crystals (2000℃-2400℃) and is used to suppress the volatilization of AlN seed crystals 4 during AlN crystal growth. In a specific embodiment of this invention, the high-temperature resistant fastener 2 is fixed to the upper surface of AlN seed crystal 4 (i.e., the side of AlN seed crystal 4 facing away from the raw material placement area 111). Since the melting point of the high-temperature resistant fastener 2 is higher than the growth temperature of AlN crystals, the high-temperature resistant fastener 2 can remain stable and solid during the growth of AlN crystals, and form a physical barrier to prevent easily volatile Al and N atoms on the surface of AlN seed crystal 4 from diffusing into the growth space 11. At the same time, in practical applications, the high-temperature resistant fastener 2 and the upper surface of AlN seed crystal 4 can be further bonded together, which can reduce local overheating of the upper surface of AlN seed crystal 4 through heat conduction, and further suppress the volatilization of AlN seed crystal 4 during AlN crystal growth.
[0045] This invention does not limit the thickness of the high-temperature resistant fastener 2, and it can be adjusted according to actual application requirements. Preferably, the thickness of the high-temperature resistant fastener 2 is 1 mm or more, to avoid the high-temperature resistant fastener 2 being too thin, which would prevent the effect of suppressing the volatilization of AlN seed crystals 4 during the growth process of AlN crystals from being achieved.
[0046] In one embodiment, the high-temperature resistant fastener 2 is a tungsten sheet with a purity greater than or equal to 99.9%. Tungsten has a melting point as high as 3422°C, far exceeding the growth temperature of AlN crystals. During AlN crystal growth, the tungsten sheet remains stable and solid, forming a physical barrier to prevent Al and N atoms volatilized from the surface of the AlN seed crystal 4 from diffusing into the growth space 11. By attaching the tungsten sheet to the upper surface of the AlN seed crystal 4, the tungsten sheet reduces localized overheating on the upper surface of the AlN seed crystal 4 through heat conduction, further suppressing the volatilization of the AlN seed crystal 4 during AlN crystal growth. Simultaneously, due to the high chemical stability of metallic tungsten, under conventional AlN crystal growth parameters, metallic tungsten reacts almost no with the AlN seed crystal 4, the growth raw materials, or the gas (such as N2) introduced during AlN crystal growth.
[0047] Of course, in other embodiments, the high-temperature fastener 2 can also be other materials with high melting points (greater than the growth temperature of AlN crystals) and chemical inertness, including but not limited to tantalum (Ta), molybdenum (Mo), tungsten-rhenium (W-Re) alloy, boron nitride (BN) and silicon carbide (SiC).
[0048] See also Figure 5 The mask 3 is disposed on the side of the AlN seed crystal 4 away from the high-temperature resistant fixing component 2, and the mask 3 has multiple through holes 31. Specifically, the mask 3 is attached to the lower surface of the AlN seed crystal 4 (i.e., the side of the AlN seed crystal 4 facing the raw material placement area 111). The mask 3 is used to prevent the raw material gas molecules from crystallizing in the area of the mask 3 without through holes 31 during the AlN crystal growth process. In other words, during the AlN crystal growth process using the physical vapor transport method, due to the large temperature difference (approximately 10℃-50℃) between the top 13 and bottom 12 of the crucible, i.e., the temperature difference between the AlN seed crystal 4 and the bottom 12 of the crucible... Due to the large temperature gradient, the AlN raw material 6 decomposes into gaseous substances such as Al and N2 at high temperatures. These gaseous substances preferentially crystallize on the lower surface of the AlN seed crystal 4 located within the through-hole 31. However, because the temperature difference between the area without the through-hole 31 on the lower surface of the mask 3 (i.e., the side of the mask 3 facing the raw material placement area 111) and the temperature at the bottom 12 of the crucible is small, and because the heat sink of the mask 3 itself is small, nucleation is difficult. Therefore, no AlN crystals will grow directly on the lower surface of the mask 3 where the through-hole 31 is not located. Once the through-hole 31 is filled with AlN crystals, the AlN crystals begin to extend beyond the through-hole 31 and grow laterally along the lower surface of the mask 3 where the through-hole 31 is not located, eventually merging into a complete AlN crystal. The laterally growing AlN crystals interrupt the continuation of defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations within the AlN seed crystal 4, improving the crystallization quality of the AlN crystal.
[0049] Combination Figure 2 and Figure 6 The AlN crystal grown using the growth apparatus provided by this invention specifically includes a first sub-crystal 51 located within each through-hole 31 and a second sub-crystal 52 connected to all the first sub-crystals 51. That is, multiple first sub-crystals 51 continue to grow downwards from the through-hole 31. After extending beyond the through-hole 31, they grow laterally along the lower surface of the mask 3 where no through-hole 31 is located, merging to form a complete AlN crystal. After forming the complete AlN crystal, it continues to grow longitudinally away from the mask 3, forming the second sub-crystal 52. Of course, the first sub-crystal 51 and the second sub-crystal 52 are an integral structure.
[0050] The first sub-crystal 51 consists of multiple independent crystals with the same shape as the through hole 31, and the second sub-crystal 52 is a complete three-dimensional structure with a certain thickness. All the first sub-crystals 51 are connected to one side of the second sub-crystal 52 in the thickness direction.
[0051] Of course, in practical applications, the obtained AlN crystal can be processed. Specifically, the second sub-crystal 52 with a complete structure can be processed, such as crystal orientation, cutting, grinding, mechanical polishing, cleaning and drying, to obtain an AlN wafer. This AlN wafer can be placed in the crucible 1 as a new AlN seed crystal for another or multiple AlN crystal growth steps, which can further reduce the defect density of the AlN crystal and improve the crystallization quality of the grown AlN crystal.
[0052] Specifically, the thickness of the mask 3 is preferably 0.2mm-0.6mm. For example, the thickness of the mask 3 can be 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, or 0.6mm. This setting avoids the mask 3 being too thin, which could easily deform at high temperatures and affect crystal quality, and also avoids the mask 3 being too thick, which could easily lead to the formation of AlN polycrystalline structures during AlN crystal growth. Of course, this invention does not limit the specific thickness of the mask 3 and can be adjusted according to actual needs.
[0053] Specifically, multiple through holes 31 are evenly arranged on the mask sheet 3.
[0054] Specifically, the spacing between two adjacent vias 31 is preferably 1mm-5mm. This avoids the situation where the spacing between two adjacent vias 31 is too small, which would prevent the final grown AlN crystal from effectively cutting off defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations within the AlN seed crystal 4. It also avoids the situation where the spacing between two adjacent vias 31 is too large, which would easily lead to the formation of AlN polycrystalline structures during lateral expansion growth on the lower surface of the mask 3, and make it difficult for the AlN crystals extending from each via 31 to merge laterally. For example, the spacing between two adjacent vias 31 can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm.
[0055] Specifically, the aperture of each through hole 31 on the mask 3 is preferably 1mm-10mm. For example, the aperture of the through hole 31 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm.
[0056] Of course, this utility model does not limit the specific size of the mask sheet 3, the number of through holes 31, the specific diameter of the through holes 31, or the spacing between two adjacent through holes 31. Based on the above-mentioned size range of the diameter of the through holes 31 and the spacing between two adjacent through holes 31, the number of through holes 31, the arrangement of the through holes 31, the diameter of the through holes 31, and the spacing between two adjacent through holes 31 can be reasonably designed on a mask sheet 3 with a fixed surface area.
[0057] In one embodiment, the mask 3 is a tungsten sheet with a purity greater than or equal to 99.9%.
[0058] Of course, in other embodiments, the mask 3 can also be other materials with high melting points (greater than the growth temperature of AlN crystals) and chemical inertness, including but not limited to tantalum (Ta) and molybdenum (Mo), to ensure that the mask 3 will not melt during the AlN crystal growth process and will not react with the gaseous molecules of the raw materials.
[0059] See also Figure 1 and Figure 2 The surface areas of the mask 3 and the high-temperature resistant fastener 2 are both larger than the surface area of the AlN seed crystal 4. When the AlN seed crystal 4 is placed between the mask 3 and the high-temperature resistant fastener 2, the projection of the mask 3 on the bottom surface of the crucible 1 and the projection of the high-temperature resistant fastener 2 on the bottom surface of the crucible 1 completely cover the projection of the AlN seed crystal 4 on the bottom surface of the crucible 1.
[0060] Of course, this utility model does not impose specific limitations on the surface area of the high-temperature resistant fixing component 2 and the surface area of the mask sheet 3. The design can be adjusted according to the surface area of the AlN seed crystal 4 and the cross-sectional area of the crystal growth area 112 in the crucible 1 in the lateral direction, so as to ensure that it is larger than the surface area of the AlN seed crystal 4 and can be fixedly placed in the crystal growth area 112.
[0061] More specifically, the crucible 1, growth space 11, high-temperature resistant fixture 2, mask 3, and through-hole 31 are all cylindrical structures. Correspondingly, the first sub-crystal 51 grown within the through-hole 31 is also a cylindrical structure.
[0062] Of course, in other embodiments, the crucible 1, growth space 11, high-temperature resistant fixture 2, mask 3 and through hole 31 may also be cubic or polyhedral structures.
[0063] See Figure 1 and Figure 2 A stepped structure 14 is provided on the side wall of the crucible 1. The stepped structure 14 is used to mount the peripheral area of the mask sheet 3 to fix the mask sheet 3 to the crucible 1. Alternatively, the stepped structure 14 can also be as follows: Figure 3 This can further increase the capacity of crucible 1. Understandably, crucible 1 and stepped structure 14 can be integrally set; or, stepped structure 14 can be fixed to the side wall of crucible 1, such as by insertion and removal, threaded fixing, inlay fixing or snap-fit fixing, etc.
[0064] In one embodiment, see Figure 1 , Figure 2 and Figure 4A portion of the crystal growth region 112 near the top 13 of the crucible extends outwards from the outer periphery of the crucible 1 sidewall, forming a stepped structure 14. This stepped structure 14 is continuously arranged around the sidewall of the crucible 1. In other words, the crystal growth region 112 includes a first region near the top 13 of the crucible and a second region near the bottom 12 of the crucible, with the lateral cross-sectional area of the first region being larger than that of the second region. During crucible assembly, the peripheral portion of the mask 3 can be mounted on the stepped structure 14 to fix the relative position of the mask 3 and the crucible 1.
[0065] In another embodiment, see Figure 3 and Figure 4 A portion of the sidewall of the crucible 1 located within the crystal growth region 112 extends toward the space inside the crucible 1, forming a stepped structure 14, which is continuously arranged around the sidewall of the crucible 1.
[0066] More specifically, the crucible 1 in this utility model includes a crucible body 15 having a growth space 11 and a crucible lid 16 covering the top of the crucible body 15.
[0067] More specifically, both the crucible body 15 and the crucible lid 16 are made of tungsten metal with a purity of 99.9% or higher.
[0068] This invention also provides an AlN crystal growth system, including a growth furnace and an AlN crystal growth apparatus as described in any of the above embodiments, wherein the AlN crystal growth apparatus is placed inside the growth furnace.
[0069] See also Figure 1 The raw material placement area 111 is used to place AlN raw material 6. The mask 3 is mounted on the stepped structure 14. The AlN seed crystal 4 is placed on the upper surface of the mask 3. The high-temperature resistant fixing component 2 is placed on the upper surface of the AlN seed crystal 4, and the centers of the high-temperature resistant fixing component 2, AlN seed crystal 4 and mask 3 are aligned as much as possible. The crucible assembly is assembled by covering it with the crucible lid 16. The crucible assembly is placed in the growth furnace to grow AlN crystal.
[0070] AlN raw material 6 is AlN powder with a purity of 99.9% or higher, and AlN raw material 6 may specifically be in powder, granular or aggregate form.
[0071] Furthermore, the growth system in this embodiment also includes a first temperature measuring device, a second temperature measuring device, and a heating device disposed within the growth furnace. The first temperature measuring device is disposed above the top 13 of the crucible and is used to obtain the temperature of the top 13 of the crucible; the second temperature measuring device is disposed below the bottom 12 of the crucible and is used to obtain the temperature of the bottom 12 of the crucible; the heating device is disposed around the outer periphery of the crucible 1 and is used to heat the growth space 11 within the crucible 1.
[0072] Specifically, both the first and second temperature measuring devices are infrared temperature measuring devices.
[0073] Furthermore, the growth system in this embodiment also includes a vacuum pumping device and a pressure boosting device connected to the growth furnace. The vacuum pumping device is used to maintain a vacuum state within the growth furnace and the growth apparatus, and the pressure boosting device is used to maintain a preset pressure within the growth furnace and the growth apparatus. Specifically, the pressure boosting device increases the pressure within the growth furnace and the growth apparatus by supplying gases such as nitrogen to the space inside the growth furnace and the growth apparatus. Through the coordinated operation of the vacuum pumping device, the pressure boosting device, the first temperature measuring device, the second temperature measuring device, and the heating device, the growth space 11 within the crucible 1 is placed in a growth environment suitable for AlN crystal growth.
[0074] In summary, the growth apparatus provided by this invention has a mask with multiple through holes on one side of the crystallization surface of the AlN seed crystal, and the mask is attached to the AlN seed crystal. The mask is used to prevent the raw material gas molecules from crystallizing in the area of the mask without through holes during the growth of AlN crystal. That is, during the growth of AlN crystal, the raw material gas molecules preferentially crystallize on the AlN seed crystal located in the through holes. When the through holes are filled with AlN crystals (i.e., the first daughter crystal), the AlN crystals begin to extend out of the through holes and grow laterally along the lower surface of the mask where there are no through holes, merging into a complete AlN crystal (i.e., the second daughter crystal). The laterally growing AlN crystal (the second daughter crystal) interrupts the continuation of defects such as crystal domains, twins, pores, screw dislocations, and edge dislocations in the AlN seed crystal, thereby improving the crystallization quality of the AlN crystal. Furthermore, the obtained second seed crystal can be processed to obtain an AlN wafer. This AlN wafer can be used as a new AlN seed crystal and placed in a crucible for another or multiple AlN crystal growth steps, which can further reduce the defect density of the AlN crystal, improve the crystallization quality of the AlN crystal, and obtain an AlN crystal with low defect density.
[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and alterations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention, and all such changes should fall within the protection scope of the claims of the present invention.
Claims
1. An apparatus for growing AlN crystals, characterized in that, include: A crucible, the interior of which forms a growth space, the growth space including a raw material placement area near the bottom of the crucible and a crystal growth area near the top of the crucible, the raw material placement area and the crystal growth area being arranged longitudinally along the growth space; A high-temperature resistant fastener is disposed in the crystal growth region for fixing an AlN seed crystal; wherein the AlN seed crystal is located on the side of the high-temperature resistant fastener facing the raw material placement area; A mask sheet is disposed on the side of the AlN seed crystal away from the high-temperature resistant fixing component, and the mask sheet is provided with multiple through holes; The AlN crystal includes a first sub-crystal located within each of the through-holes and a second sub-crystal connected to all the first sub-crystals. The mask is used to prevent the raw material gas molecules from crystallizing in the area of the mask where the through-holes are not provided during the growth of the AlN crystal.
2. The AlN crystal growth apparatus according to claim 1, characterized in that, The thickness of the mask is 0.2mm-0.6mm.
3. The AlN crystal growth apparatus according to claim 1, characterized in that, The plurality of through holes are evenly arranged on the mask, and the spacing between two adjacent through holes is 1mm-5mm; And / or, the diameter of the through hole is 1mm-10mm; And / or, the mask is a tungsten sheet.
4. The AlN crystal growth apparatus according to claim 1, characterized in that, The thickness of the high-temperature resistant fastener is 1 mm or more; And / or, the high-temperature resistant fastener is a tungsten sheet; And / or, the melting point of the high-temperature resistant fastener is higher than the growth temperature of the AlN crystal, which is used to suppress the volatilization of the AlN seed crystal during the growth of the AlN crystal.
5. The AlN crystal growth apparatus according to claim 1, characterized in that, The surface area of the mask and the surface area of the high-temperature resistant fastener are both greater than the surface area of the AlN seed crystal. When the AlN seed crystal is placed between the mask and the high-temperature resistant fastener, the projection of the mask on the bottom surface of the crucible and the projection of the high-temperature resistant fastener on the bottom surface of the crucible completely cover the projection of the AlN seed crystal on the bottom surface of the crucible.
6. The AlN crystal growth apparatus according to claim 1, characterized in that, Both the mask and the high-temperature resistant fastener are cylindrical structures; And / or, the through hole is a cylindrical structure, a cubic structure, or a polyhedral structure.
7. The AlN crystal growth apparatus according to claim 1, characterized in that, The crucible has a stepped structure on its side wall, which is used to support the peripheral area of the mask sheet to fix the mask sheet and the crucible. And / or, the crucible includes a crucible body having the growth space and a crucible lid covering the top of the crucible body.
8. An AlN crystal growth system, comprising a growth furnace and an AlN crystal growth apparatus as described in any one of claims 1-7, wherein the growth apparatus is placed inside the growth furnace; in, The raw material placement area is used to place AlN raw materials.
9. The AlN crystal growth system according to claim 8, characterized in that, The growth system also includes a first temperature measuring device, a second temperature measuring device, and a heating device disposed inside the growth furnace; The first temperature measuring device is positioned above the top of the crucible to obtain the temperature at the top of the crucible. The second temperature measuring device is located below the bottom of the crucible and is used to obtain the temperature of the bottom of the crucible; The heating device is arranged around the crucible and is used to heat the growth space inside the crucible.
10. The AlN crystal growth system according to claim 8 or 9, characterized in that, The growth system also includes a vacuum pumping device and a pressure boosting device connected to the growth furnace. The vacuum pumping device is used to make the space inside the growth furnace and the growth device a vacuum state, and the pressure boosting device is used to make the pressure inside the growth furnace and the growth device a preset pressure.