Silicon carbide crystal growth device

Abstract

The invention provides a silicon carbide crystal growth device. The silicon carbide crystal growth device comprises a crucible, wherein the crucible comprises a crucible bottom, a crucible body and a crucible cover; a first porous graphite barrel; a graphite ring; a support ring; a second porous graphite barrel; the seed crystal assembling part is arranged on one side of the second porous graphite barrel and comprises a seed crystal; the graphite block assembling part is positioned on one side, close to the crucible bottom, of the seed crystal assembling part; the graphite block assembling part is characterized in that a first supporting step is arranged at the bottom of the annular inner edge of an annular graphite block support; the first graphite paper is located in the ring inner area of the annular graphite block support and is supported on the first supporting step; the graphite block is located on the surface, close to the crucible bottom, of the first graphite paper, and a first distance is formed between the graphite block and the first supporting step; the seed crystal ring is connected to the ring inner surface of the annular graphite block support and pressed on the surface of the first graphite paper, the seed crystal ring, the first graphite paper and the seed crystal assembly part form a closed space, and the seed crystal is located in the closed space. The growth quality of silicon carbide crystals is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a silicon carbide crystal growth device. Background Art

[0002] A key indicator of silicon carbide substrates is dislocation density. Currently, epitaxy requirements for the dislocation density of 6-8 inch silicon carbide substrates (such as screw dislocations (TSDs), basal plane dislocations (BPDs), and edge dislocations (TEDs)) are stringent. Dislocations have a significant impact on the epitaxial layer of silicon carbide substrates. Most BPDs in silicon carbide substrates convert to TED dislocations during the initial stages of epitaxial growth. The few BPDs that penetrate the epitaxial layer can affect the stability of bipolar devices (such as pin diodes, BJTs, and IGBTs). TSDs can easily induce small pit defects, carrot defects, triangle defects, and step aggregation on the epitaxial layer surface, increasing reverse leakage current and impacting device performance, yield, and reliability. TEDs generally have a minimal impact on device performance. Furthermore, dislocation defects are also a key factor affecting substrate yield. In addition to the three basic typical dislocations mentioned above, dislocation defects often manifest as mixed dislocations and other forms.

[0003] During the crystal growth process, there are several mixed dislocation manifestations that seriously affect the substrate yield: the first type has a typical morphology of an emitting five-pointed star, which is a "star dislocation", such as Figure 1 As shown in Figure 1 ; the second type is a mixed dislocation region composed of a single or more dislocations clustered or connected, such as a dislocation-dense region formed by multiple BPDs, TEDs, and a small number of TSDs. The first type of "star dislocation" is highly heritable and destructive. "Star dislocations" in the substrate typically manifest in two forms: one is scattered throughout the first two or three substrate sheets near the seed crystal end, with clear heritability when compared to their distribution; the other is densely distributed across the entire surface, starting from the seed crystal end and extending all the way to the growth cutoff. Therefore, "star dislocations" are severely destructive to both the substrate and the seed crystal (the raw material used to grow the substrate). Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one object of the present invention is to provide a silicon carbide crystal growth apparatus that can effectively reduce the dislocation density in the grown silicon carbide crystal.

[0005] In one aspect of the present invention, the present invention provides a silicon carbide crystal growth device. According to an embodiment of the present invention, the silicon carbide crystal growth device includes: a crucible, the crucible includes a crucible bottom, a crucible body and a crucible cover, the crucible bottom and the crucible cover are arranged on both sides of the crucible body opposite to each other and define a cavity; a first porous graphite barrel, the first porous graphite barrel is located on the crucible bottom and defines a material placement space between the first porous graphite barrel and the crucible body; a graphite ring, the graphite ring is arranged at the top of the material placement space; a support ring, the support ring is arranged on the side of the graphite ring away from the crucible bottom; a second porous graphite barrel, the second porous graphite barrel is arranged on the side of the support ring away from the crucible bottom and is located on the side of the support ring away from the edge of the crucible body; a seed crystal assembly component, the seed crystal assembly component is arranged on the side of the second porous graphite barrel away from the crucible bottom, the seed crystal assembly component includes a seed crystal; An ink block assembly component, wherein the graphite block assembly component is located on a side of the seed crystal assembly component close to the bottom of the crucible, and the graphite block assembly component includes: an annular graphite block holder, wherein the bottom of the inner edge of the annular graphite block holder has a first supporting step; a first graphite paper, wherein the first graphite paper is located in the inner region of the annular graphite block holder and is supported on the first supporting step; a graphite block, wherein the graphite block is located on the surface of the first graphite paper close to the bottom of the crucible and has a first spacing from the first supporting step; a seed crystal ring, wherein the seed crystal ring is connected to the inner surface of the annular graphite block holder, pressed on the surface of the first graphite paper, and located above the first supporting step; the seed crystal ring, the first graphite paper, and the seed crystal assembly component constitute a closed space, and the seed crystal is located in the closed space. Therefore, it can be seen from the above structure that it is necessary to assemble the graphite block assembly component first and then the seed crystal assembly component. After assembling the graphite block assembly component, the graphite particles on the back side of the first graphite paper to which the graphite block is adhered (i.e., the side away from the bottom of the crucible) can be cleaned to avoid contamination of the seed crystal by the graphite particles during the assembly of the graphite block assembly component; the formation of the above-mentioned closed space can effectively protect the seed crystal during the assembly of the crystal growth device (or thermal field) and the initial stage of crystal growth, and complete the isolation of the graphite particles adsorbed on the surface of the seed crystal, thereby helping to improve the growth quality of the silicon carbide crystal.

[0006] According to an embodiment of the present invention, the first spacing is 5 to 10 mm.

[0007] According to an embodiment of the present invention, the graphite block assembly component is located on a side of the second porous graphite barrel away from the bottom of the crucible.

[0008] According to an embodiment of the present invention, the graphite block assembly component is located on a side of the second porous graphite barrel close to the bottom of the crucible.

[0009] According to an embodiment of the present invention, the seed crystal assembly component includes: an annular seed crystal holder, the bottom of the inner edge of the annular seed crystal holder has a second supporting step and is fixedly connected to the inner wall of the seed crystal ring; a second graphite paper, the second graphite paper is located in the inner area of the annular seed crystal holder and is supported on the second supporting step; the seed crystal is located on the surface of the second graphite paper close to the bottom of the crucible and has a second distance between it and the second supporting step; an annular seed crystal block, the annular seed crystal block is located on one side of the inner surface of the annular seed crystal holder, pressed on the surface of the second graphite paper, and located above the second supporting step.

[0010] According to an embodiment of the present invention, the silicon carbide crystal growth device further satisfies at least one of the following conditions: the graphite block assembly component further includes a fixing ring, which is located on the outside of the annular graphite block holder and is matched with the annular graphite block holder for fixing the graphite block assembly component; the second spacing is 0.1 to 0.15 mm; and the annular seed crystal holder is connected to the seed crystal ring by threads.

[0011] According to an embodiment of the present invention, the seed crystal assembly component includes: an annular seed crystal holder, the two ends of which are respectively connected to the crucible body and the surface of the second porous graphite barrel away from the bottom of the crucible; a graphite gasket, the graphite gasket is located on the surface of the other part of the second porous graphite barrel away from the bottom of the crucible; a second graphite paper, the second graphite paper is located on the side of the second porous graphite barrel away from the bottom of the crucible and is supported on the surface of the graphite gasket; the seed crystal is located on the surface of the second graphite paper close to the bottom of the crucible and has a third distance between it and the graphite gasket; an annular seed crystal block, the annular seed crystal block is located on one side of the inner surface of the annular seed crystal holder, pressed on the surface of the second graphite paper, and located above the graphite gasket.

[0012] According to an embodiment of the present invention, the seed crystal assembly component also satisfies at least one of the following conditions: the distance between the seed crystal and the graphite block is 30 to 35 mm; the surface of the second porous graphite barrel away from the bottom of the crucible includes a first surface area and a second surface area, the first surface area is arranged in contact with the annular seed crystal holder, and the second surface area is arranged in contact with the graphite gasket ring, and the first surface area and the second surface area are not on the same surface; the third distance is 0.1 to 0.15 mm.

[0013] According to an embodiment of the present invention, the annular seed crystal holder and the annular seed crystal pressing block are arranged in affixed relation, and a fitting gap between the annular seed crystal holder and the annular seed crystal pressing block is less than or equal to 0.2 mm.

[0014] According to an embodiment of the present invention, the silicon carbide crystal growth device further includes: a soft graphite felt, which is arranged on the surface of the crucible bottom in the first porous graphite barrel.

[0015] According to an embodiment of the present invention, the graphite block holder and the seed crystal ring are connected via threads.

[0016] According to an embodiment of the present invention, the silicon carbide crystal growth device also includes: a graphite sheet, which is arranged on the side of the seed crystal assembly component away from the bottom of the crucible; a first thermal insulation felt, which is arranged between the graphite sheet and the crucible cover; and a temperature measuring hole, which passes through the first thermal insulation felt and the crucible cover, and whose orthographic projection in the vertical direction is located within the orthographic projection of the seed crystal in the vertical direction.

[0017] According to an embodiment of the present invention, the silicon carbide crystal growth device also includes: a second thermal insulation felt, which is arranged on the outside of the crucible and has a through hole connected to the temperature measuring hole; a storage table, which includes a carrier and a tray placed on the carrier, and the tray is used to place the crucible; a quartz tube, which has a sealed chamber for placing the crucible; and an induction coil, which is arranged on the outside of the quartz tube for heating.

[0018] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 This is a schematic diagram of a "star dislocation";

[0021] Figure 2 1 is a schematic structural diagram of a silicon carbide crystal growth device according to an embodiment of the present invention;

[0022] Figure 3 It is a structural schematic diagram of another graphite block assembly component and seed crystal assembly component of the present invention;

[0023] Figure 4 yes Figure 2 and Figure 3 Explosion diagram of the graphite block assembly;

[0024] Figure 5 yes Figure 2 and Figure 3 Exploded image of the seed crystal assembly components;

[0025] Figure 6It is a structural schematic diagram of another graphite block assembly component and seed crystal assembly component of the present invention;

[0026] Figure 7 This is a schematic diagram after crystal growth is completed in another embodiment of the present invention;

[0027] Figure 8 It is a structural schematic diagram of another silicon carbide crystal growth device of the present invention;

[0028] Figure 9 yes Figure 8 Schematic diagram of the structure of the seed crystal assembly components, where: Figure 9 (2) in the Figure 9 The enlarged view of the circle in (1);

[0029] Figure 10 yes Figure 8 Exploded image of the seed crystal assembly components;

[0030] Figure 11 This is a schematic diagram after crystal growth is completed in another embodiment of the present invention;

[0031] Figure 12 It is a structural schematic diagram of another silicon carbide crystal growth device of the present invention;

[0032] Figure 13 It is a structural schematic diagram of another silicon carbide crystal growth device of the present invention.

[0033] Figure 1: Crucible bottom 11; Crucible body 12; Crucible cover 13; Silicon carbide powder 20; First porous graphite barrel 21; Graphite ring 30; Support ring 40; Second porous graphite barrel 22; Graphite assembly 50; Annular graphite block holder 51; First support step 511; First graphite paper 52; Graphite block 53; Seed crystal ring 54; Fixed ring 55; Seed crystal assembly 60; Annular seed crystal holder 61; Second support step 611; Second graphite paper 62; Seed crystal 63; Annular seed crystal pressing block 64; Graphite gasket 65; Graphite sheet 70; First insulation felt 80; Temperature measuring hole 81; Graphite soft felt 90; Silicon carbide polycrystal 0; Silicon carbide crystal 6; Second insulation felt 100; Through hole 101; Storage table 110; Carrier 111; Tray 112; Quartz tube 120; Induction coil 130. DETAILED DESCRIPTION

[0034] The scheme of the present invention will be explained below with reference to the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications shall be followed.

[0035] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0036] In one aspect of the present invention, the present invention provides a silicon carbide crystal growth device. Figure 2 , the silicon carbide crystal growth device comprises:

[0037] Crucible, the crucible includes a crucible bottom 11, a crucible body 12 and a crucible cover 13. The crucible bottom 11 and the crucible cover 13 are arranged on both sides of the crucible body 12 and define a cavity, wherein the first porous graphite barrel 21, graphite ring 30, support ring 40, second porous graphite barrel 22, seed crystal assembly 60, graphite assembly 50 and other structures described below are all located in the cavity;

[0038] A first porous graphite barrel 21 is located on the crucible bottom 11 and defines a material storage space between the first porous graphite barrel 21 and the crucible body 12. The material storage space is used to store silicon carbide powder 20. After the silicon carbide powder is heated to generate a gaseous component, the gaseous component can be filtered through the first porous graphite barrel to filter out inclusions in the gaseous component, and the gaseous component can escape into the first porous graphite barrel and move upward to participate in the growth of silicon carbide crystals.

[0039] A graphite ring 30 is provided at the top of the material storage space to seal the material storage space and prevent the silicon carbide powder from overflowing;

[0040] A support ring 40 is provided on a side of the graphite ring away from the bottom of the crucible;

[0041] The second porous graphite barrel 22 is arranged on the side of the support ring 40 away from the crucible bottom 11, and is located on the side of the support ring 40 away from the edge of the crucible body 12. In the present invention, the arrangement of the second porous graphite barrel allows a portion of the rising gas phase components to move toward the outer cavity edge (i.e., toward the cavity area between the crucible body and the second porous graphite barrel), thereby playing the role of exhaust and component collection. The polycrystalline deposition in the cavities on both sides is more serious. The height of the second porous graphite barrel 22 can be adjusted according to the mass of the polycrystalline deposited in the cavities on both sides. For example, if it exceeds 20% of the weight of the grown silicon carbide crystals, the height of the second porous graphite barrel in this section can be appropriately reduced;

[0042] A seed crystal assembly 60 is provided on a side of the second porous graphite barrel 22 away from the crucible bottom 11 , and includes a seed crystal 63 ;

[0043] Graphite block assembly 50, see Figure 3 、 Figure 4 and Figure 5The graphite block assembly 50 is located on the side of the seed crystal assembly 60 close to the crucible bottom 11. The graphite block assembly 50 includes: an annular graphite block holder 51, the bottom of the inner edge of the annular graphite block holder 51 has a first supporting step 511; a first graphite paper 52, the first graphite paper 52 is located in the inner area of the annular graphite block holder 51 and is supported on the first supporting step 511; a graphite block 53, the graphite block 53 is located on the surface of the first graphite paper 52 close to the crucible bottom 11, and has a first distance S1 between it and the first supporting step 511; a seed crystal ring 54, the seed crystal ring 54 is connected to the inner surface of the annular graphite block holder 51, and is pressed on the surface of the first graphite paper 52, and is located above the first supporting step 511. The seed crystal ring 54, the first graphite paper 52 and the seed crystal assembly 60 constitute a closed space 1, and the seed crystal 63 is located in the closed space 1.

[0044] According to an embodiment of the present invention, it can be seen from the above structure that it is necessary to assemble the graphite block assembly component first and then the seed crystal assembly component. After assembling the graphite block assembly component, the graphite particles on the back side of the first graphite paper to which the graphite block is adhered (i.e., the side away from the bottom of the crucible) can be cleaned to avoid contamination of the seed crystal by the graphite particles during the assembly of the graphite block assembly component; the formation of the above-mentioned closed space can effectively protect the seed crystal during the assembly of the crystal growth device (or thermal field) and the initial stage of crystal growth, and complete the isolation of the graphite particles adsorbed on the surface of the seed crystal, thereby reducing the dislocation density, especially effectively reducing the density of "star dislocations", and thus helping to improve the growth quality of silicon carbide crystals.

[0045] Specifically:

[0046] In current silicon carbide crystal growth devices, the crucible is strictly cleaned in advance before assembling the seed crystal assembly components. However, during the assembly process of the seed crystal assembly components, the seed crystal is arranged last in the assembly order (the seed crystal is at the top and must be introduced after the bottom components are assembled), and after the seed crystal is arranged, it is usually sealed with a graphite cover, etc., which makes it easy to generate graphite particles again in the above process. These graphite particles are completely unobservable after thermal field packaging and cannot be removed. Moreover, the graphite particles generated by wear and tear during the assembly process are usually small in size. Due to the mirror reaction generated by chemical mechanical polishing of the seed crystal growth surface, it is easy to adsorb free small particles. This causes particles attached to the surface of the growth surface, usually graphite particles, to cause local stress, which is also an important reason for inducing dislocations and dislocation aggregation. More serious cases include carbon encapsulation, polycrystalline and polymorphic phase transitions. To address this problem, in the device of the present invention, since the seed crystal is located in the above-mentioned closed space, even if graphite particles are produced again during the subsequent assembly of the graphite cover (or crucible cover), these graphite particles will not fall into the closed space, that is, they will not contaminate the seed crystal, thereby reducing the dislocation density in the growing crystal, especially effectively reducing the density of "star dislocations".

[0047] Furthermore, in existing silicon carbide crystal growth devices, unstable pressure and temperature conditions in the early stages of crystal growth lead to an imbalance in component ratios, resulting in poor initial crystal quality and affecting subsequent crystal growth. To address this issue, in the silicon carbide crystal growth device of the present invention, due to the barrier of the first graphite paper, gaseous components cannot enter the enclosed space and contact the seed crystal during the initial start-up reaction. This means that crystal growth cannot proceed in the early stages, and thus poor-quality silicon carbide crystals will not be grown. In the present invention, as the temperature rises and the pressure decreases, the components in the silicon carbide powder begin to decompose due to heat. First, a reaction occurs in the suspended first graphite paper segment between the edge of the graphite block and the first support step (i.e., the first graphite paper segment corresponding to the first spacing). This is because the annular graphite block support and the graphite block are induction heated to a higher temperature, and the graphite paper with a relatively low temperature will adsorb the silicon carbide components to cause polycrystalline aggregation, thereby making the graphite paper brittle. Under the counterweight of the graphite block, the edge of the first graphite paper breaks and eventually falls off after a certain period of time. At this time, graphite particles and the like during the assembly process and in the early stage of thermal decomposition of the components are blocked under the graphite block. When crystallization is carried out after the atmosphere stabilizes, it will not have any impact on the growth surface of the seed crystal, reducing the dislocation density, especially the density of "star dislocations", thereby improving the growth quality of the silicon carbide crystal.

[0048] According to some embodiments of the present invention, the first spacing is 5 to 10 mm, such as 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc. Therefore, the distance between the graphite block 53 and the first supporting step 511 can prevent particles from being adsorbed on the surface of the seed crystal in the early stage of thermal decomposition of the silicon carbide component, and can also make the first graphite paper in the gap break after the atmosphere under temperature, pressure and other conditions stabilizes, and the graphite block and the first graphite paper fall to the bottom surface of the crucible, such as Figure 7 As shown, the contact between the gas phase component and the seed crystal is achieved to perform crystallization; if the first spacing of the gap is too small, breakage is not easy to occur, which affects the growth of the crystal; if the first spacing of the gap is too large, it may cause the graphite block to be unable to hang stably on the first graphite paper, or cause the first graphite paper to break too quickly, and the powder produced by the early stage of thermal decomposition of the silicon carbide component is still adsorbed on the surface of the seed crystal, affecting the quality of crystal growth.

[0049] According to some embodiments of the present invention, the material of the annular graphite block support 51 , the seed crystal ring 54 and other structures may be graphite.

[0050] According to some embodiments of the present invention, referring to Figure 2 and Figure 8The silicon carbide crystal growth device further includes a graphite felt 90 disposed on the surface of the crucible bottom 11 within the first porous graphite barrel 21. The graphite felt 90 has a certain degree of flexibility, and its arrangement serves as a buffer and shock absorber, mitigating the impact of the top graphite block falling off.

[0051] According to some embodiments of the present invention, in the structure of the graphite block assembly component 50, the annular graphite block support 51 and the seed crystal ring 54 are connected by threads, thereby achieving good fixation.

[0052] According to some embodiments of the present invention, the specific placement of the graphite block assembly can include the following two positions: the graphite block assembly 50 is located on the side of the second porous graphite barrel 22 away from the crucible bottom 11, or the graphite block assembly 50 is located on the side of the second porous graphite barrel 22 close to the crucible bottom 11, that is, the graphite block assembly is located at the top or bottom of the second porous graphite barrel 22. Different placement positions of the graphite block assembly can correspond to seed crystal assembly components with different structures. The structure of the seed crystal assembly is described in detail below according to some embodiments of the present invention, as follows:

[0053] In some embodiments of the present invention, the graphite block assembly 50 is located on the side of the second porous graphite barrel 22 away from the crucible bottom 11, that is, the graphite block assembly is located at the top of the second porous graphite barrel 22. Figure 2 、 Figure 3 and Figure 5 The seed crystal assembly component 60 includes: an annular seed crystal holder 61, the bottom of the inner edge of the annular seed crystal holder 61 has a second supporting step 611, and is fixedly connected to the inner wall of the seed crystal ring 54; a second graphite paper 62, the second graphite paper 62 is located in the inner area of the annular seed crystal holder 61 and is supported on the second supporting step 611; the seed crystal 63 is located on the surface of the second graphite paper 62 close to the crucible bottom 11, and has a second distance S2 between it and the second supporting step 611; an annular seed crystal pressing block 64, the annular seed crystal pressing block 64 is located on one side of the inner surface of the annular seed crystal holder 61, and is pressed on the surface of the second graphite paper 62, and is located above the second supporting step 611. The seed crystal assembly component 60 of the above structure can fix the seed crystal 63 very well, and due to the obstruction of the second graphite paper, it can prevent graphite particles from being adsorbed on the surface of the seed crystal during the subsequent assembly of other structures; in addition, the center of the annular seed crystal block is designed so that after the assembly of the annular seed crystal block, the annular seed crystal holder and the seed crystal is completed, graphite particles generated during the assembly process and remaining on the back of the second graphite paper to which the seed crystal is adhered can be promptly discovered and cleaned (if graphite particles are found, they must be blown clean with alcohol, a vacuum cleaner or a compressed air gun) to prevent the graphite particles from having a significant impact on the back of the seed crystal at high temperature (graphite particles will not be decomposed at the crystal growth temperature; on the contrary, they are likely to cause local temperature differences and some silicon components to participate in the reaction).

[0054] In some embodiments, Figure 2 In the silicon carbide crystal growth device of the structure, after the silicon carbide crystal is grown, the graphite block 53 and the first graphite paper 52 fall onto the surface of the crucible bottom 11, and silicon carbide polycrystal 0 is deposited in the cavity on both sides between the second porous graphite barrel 22 and the crucible body 12, and silicon carbide crystal 6 is grown at the original seed crystal. The structural schematic diagram can be referred to Figure 7 .

[0055] In some embodiments, reference Figure 2 and Figure 6 The graphite block assembly further includes a fixing ring 55, which is located outside the annular graphite block holder 51 and matches the annular graphite block holder 51 to fix the graphite block assembly 50. In some embodiments, the fixing ring can be made of graphite.

[0056] In some embodiments, the second spacing S2 is 0.1 to 0.15 mm, such as 0.1 mm, 0.12 mm, 0.13 mm, 0.14 mm, or 0.15 mm. This can avoid contact between the seed crystal and the graphite and allow the seed crystal to adhere well to the second graphite paper, preventing the second graphite paper from breaking.

[0057] In some embodiments, reference Figure 2 and Figure 6 The annular seed crystal holder 61 is connected to the seed crystal ring 54 by screw threads, thereby achieving good connection fixity.

[0058] In some embodiments, reference Figure 2 and Figure 6 The annular seed crystal holder 61 and the annular seed crystal pressing block 64 are fitted together, and the fitting gap between the annular seed crystal holder 61 and the annular seed crystal pressing block 64 is less than or equal to 0.2 mm, such as 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm or 0. Therefore, the annular seed crystal holder 61 and the annular seed crystal pressing block 64 are connected in a non-threaded manner, but in a tightly fitting manner, that is, the annular seed crystal pressing block 64 is tightly fitted to the inner ring surface of the annular seed crystal holder 61, so that after the annular seed crystal pressing block is placed, it can press the edge of the second graphite paper and effectively fix the seed crystal; moreover, the above-mentioned smooth surface fitting method can greatly reduce the graphite particles generated during the assembly process of the annular seed crystal holder 61 and the annular seed crystal pressing block 64.

[0059] In some embodiments of the present invention, the graphite block assembly 50 is located on the side of the second porous graphite barrel 22 close to the crucible bottom 11, that is, the graphite block assembly 50 is located at the bottom end of the second porous graphite barrel 22, Figure 8 、 Figure 9 、 Figure 10 ( Figure 9 and Figure 10 In order to illustrate the structure more clearly, the second porous graphite barrel 22 is shown in the figure. The seed crystal assembly component 60 includes: an annular seed crystal holder 61, the two ends of which are respectively connected to the crucible body 12 and the surface of the second porous graphite barrel 22 away from the crucible bottom 11; a graphite gasket 65, the graphite gasket 65 is located on the surface of another part of the second porous graphite barrel 22 away from the crucible bottom 11; a second graphite paper 62, the second graphite paper 62 is located on the surface of the second porous graphite barrel 22 away from the crucible bottom 11; From the side of the crucible bottom 11, and supported on the surface of the graphite gasket 65; the seed crystal 63 is located on the surface of the second graphite paper 62 close to the crucible bottom 11, and has a third distance S3 between it and the graphite gasket 65. Furthermore, there is also a certain gap between the seed crystal and the graphite gasket, that is, the two are not in contact; the annular seed crystal pressing block 64, the annular seed crystal pressing block 64 is located on one side of the inner surface of the annular seed crystal holder 61, and is pressed on the surface of the second graphite paper 62, and is located above the graphite gasket 65. The seed crystal assembly component 60 of the above structure can fix the seed crystal 63 very well, and due to the obstruction of the second graphite paper, it can prevent graphite particles from being adsorbed on the surface of the seed crystal during the subsequent assembly of other structures; in addition, the center of the annular seed crystal block is designed so that after the annular seed crystal block, the annular seed crystal holder and the seed crystal are assembled, graphite particles generated during the assembly process and remaining on the back of the second graphite paper with the seed crystal adhered can be promptly discovered and cleaned (if graphite particles are found, they must be blown clean with alcohol, a vacuum cleaner or a compressed air gun) to prevent the graphite particles from having a significant impact on the back of the seed crystal at high temperature (graphite particles will not be decomposed at the crystal growth temperature, on the contrary, they are likely to cause local temperature differences and some silicon components to participate in the reaction); further, compared Figure 2 and Figure 3 In the silicon carbide crystal growth device, the distance between the graphite block assembly 50 and the seed crystal assembly 60 is enlarged, that is, the length of the closed space is enlarged, or in other words, the distance between the seed crystal 63 and the graphite block 53 is enlarged, thereby reducing the heat radiation generated by the first graphite paper after being heated, reducing the thermal stress generated by the heat radiation, and further reducing the dislocation aggregation, linear or "star" dislocation; at the same time, compared with Figure 2 and Figure 3 The structure of the silicon carbide crystal growth device also reduces the distance between the graphite block assembly component 50 and the crucible bottom 11, reducing the impact of the falling graphite block on the thermal field stability.

[0060] In some embodiments, Figure 8 In the silicon carbide crystal growth device of the structure, after the silicon carbide crystal 6 is grown, the graphite block 53 and the first graphite paper 52 fall onto the surface of the crucible bottom 11, and silicon carbide polycrystal 0 is deposited in the cavity on both sides between the second porous graphite barrel 22 and the crucible body 12, and the silicon carbide crystal 6 is grown at the original seed crystal. The structural schematic diagram can be referred to Figure 11 .

[0061] In some embodiments, as Figure 8 As shown, before the graphite block falls, the distance between the seed crystal 63 and the graphite block 53 is 30-35 mm, such as 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, etc. This distance increases the length of the enclosed space, thereby reducing the upward heat radiation generated by the first graphite paper after heating, reducing the thermal stress generated by the heat radiation, and thus reducing the clustering of dislocations, such as linear or "star" dislocations. If the distance between the seed crystal 63 and the graphite block 53 is relatively small, the upward heat radiation generated by the first graphite paper after heating may cause the crystal to generate large thermal stress in the early stages of growth due to the large heat radiation. The concentrated manifestation of thermal stress is dislocation clustering, linear or "star" dislocations, which may result in a relatively high dislocation density. If the distance is too large, a higher second porous graphite barrel is required. In this case, more polycrystalline may be deposited in the cavities on both sides, which is not conducive to improving the yield. The size of the distance can be adjusted by adjusting the height of the second porous graphite barrel.

[0062] In some embodiments, reference Figures 8 to 10 The surface of the second porous graphite barrel 22, away from the crucible bottom 11, includes a first surface area and a second surface area. The first surface area is in contact with the annular seed crystal holder 61, while the second surface area is in contact with the graphite backing ring 65. The first and second surface areas are not on the same surface. Therefore, this staggered arrangement of the first and second surface areas can further enhance the stability of the annular seed crystal holder and the graphite backing ring.

[0063] In some embodiments, the third spacing S3 is 0.1 to 0.15 mm, such as 0.1 mm, 0.12 mm, 0.13 mm, 0.14 mm, or 0.15 mm. This can avoid contact between the seed crystal and the graphite and allow the seed crystal to adhere well to the second graphite paper, preventing the second graphite paper from breaking.

[0064] In some embodiments, the annular seed crystal holder 61 is fitted with the annular seed crystal pressing block 64, and the fitting gap between the annular seed crystal holder and the annular seed crystal pressing block is less than or equal to 0.2 mm, such as 0.2 mm, 0.15 mm, 0.1 mm, 0.05 mm, or 0. Therefore, the annular seed crystal holder 61 and the annular seed crystal pressing block 64 are connected in a non-threaded manner, but in a tightly fitting manner, that is, the annular seed crystal pressing block 64 is tightly fitted to the inner ring surface of the annular seed crystal holder 61, so that after the annular seed crystal pressing block is placed, it can press the edge of the second graphite paper and effectively fix the seed crystal; moreover, the above-mentioned smooth surface fitting method can greatly reduce the graphite particles generated during the assembly process of the annular seed crystal holder 61 and the annular seed crystal pressing block 64.

[0065] According to some embodiments of the present invention, referring to Figure 2 and Figure 8 The silicon carbide crystal growth apparatus further includes: a graphite sheet 70 disposed on the side of the seed crystal assembly 60 away from the crucible bottom 11; a first insulation felt 80 disposed between the graphite sheet 70 and the crucible lid 13; and a temperature measuring hole 81 extending through the first insulation felt 80 and the crucible lid 13, with its vertical projection located within the vertical projection of the seed crystal 63. Alternatively, the temperature measuring hole is located above the seed crystal. Thus, the graphite sheet serves to encapsulate the seed crystal assembly, the graphite block assembly, and other components, completing a closed structure. The first insulation felt provides insulation and maintains stable power. In some embodiments, the temperature measuring hole is located in the middle of the seed crystal, or the vertical projection of the temperature measuring hole 81 is located in the middle of the vertical projection of the seed crystal 63. This improves temperature measurement accuracy. The "vertical direction" mentioned above refers to the longitudinal extension of the crucible.

[0066] According to some embodiments of the present invention, referring to Figure 12 and Figure 13 The silicon carbide crystal growth apparatus further includes: a second insulation felt 100, which is disposed outside the crucible and has a through hole 101 communicating with the temperature measuring hole 81; a storage platform 110, which includes a carrier 111 and a tray 112 disposed on the carrier 111 for placing the crucible; a quartz tube 120, which has a sealed chamber for placing the crucible; and an induction coil 130, which is disposed outside the quartz tube 120 and is used for induction heating. The second insulation felt thus further insulates the crucible to maintain stable temperature and power, and the quartz tube can achieve a vacuum environment.

[0067] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0068] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0069] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A silicon carbide crystal growth device, characterized in that: include: A crucible, comprising a crucible bottom, a crucible body, and a crucible cover, wherein the crucible bottom and the crucible cover are arranged on opposite sides of the crucible body and define a cavity; a first porous graphite barrel, the first porous graphite barrel being located on the bottom of the crucible and defining a material placement space between the first porous graphite barrel and the crucible body; A graphite ring, the graphite ring being arranged at the top of the material placement space; A support ring, the support ring being arranged on a side of the graphite ring away from the bottom of the crucible; a second porous graphite barrel, the second porous graphite barrel being arranged on a side of the support ring away from the bottom of the crucible and located on a side of the support ring away from an edge of the crucible body; A seed crystal assembly component, the seed crystal assembly component is arranged on a side of the second porous graphite barrel away from the bottom of the crucible, and the seed crystal assembly component includes a seed crystal; A graphite block assembly component, the graphite block assembly component is located on a side of the seed crystal assembly component close to the bottom of the crucible, the graphite block assembly component comprising: an annular graphite block holder, the bottom of the inner edge of the annular graphite block holder having a first supporting step; a first graphite paper, the first graphite paper being located in the inner region of the annular graphite block holder and supported on the first supporting step; a graphite block, the graphite block being located on the surface of the first graphite paper close to the bottom of the crucible and having a first spacing therebetween; a seed crystal ring, the seed crystal ring being connected to the inner surface of the annular graphite block holder, pressed onto the surface of the first graphite paper, and located above the first supporting step; the seed crystal ring, the first graphite paper, and the seed crystal assembly forming a closed space, and the seed crystal being located within the closed space.

2. The silicon carbide crystal growth device according to claim 1, characterized in that: The first spacing is 5 to 10 mm.

3. The silicon carbide crystal growth device according to claim 1, characterized in that: The graphite block assembly component is located on a side of the second porous graphite barrel away from the bottom of the crucible.

4. The silicon carbide crystal growth device according to claim 1, characterized in that: The graphite block assembly component is located on a side of the second porous graphite barrel close to the bottom of the crucible.

5. The silicon carbide crystal growth device according to claim 3, characterized in that: The seed crystal assembly comprises: An annular seed crystal holder, wherein the bottom of the inner edge of the annular seed crystal holder has a second supporting step and is fixedly connected to the inner wall of the seed crystal ring; a second graphite paper, the second graphite paper being located in an inner region of the annular seed holder and supported on the second supporting step; The seed crystal is located on the surface of the second graphite paper close to the bottom of the crucible and has a second distance from the second supporting step; An annular seed crystal pressing block is located on one side of the inner surface of the annular seed crystal holder, is pressed on the surface of the second graphite paper, and is located above the second supporting step.

6. The silicon carbide crystal growth device according to claim 5, characterized in that: The graphite block assembly component further includes a fixing ring, which is located outside the annular graphite block holder and matches the annular graphite block holder to fix the graphite block assembly component; The second spacing is 0.1 to 0.15 mm; The annular seed crystal holder is connected to the seed crystal ring via threads.

7. The silicon carbide crystal growth device according to claim 4, characterized in that: The seed crystal assembly comprises: An annular seed crystal holder, the two ends of which are respectively connected to the crucible body and a portion of the surface of the second porous graphite barrel away from the bottom of the crucible; a graphite gasket ring, the graphite gasket ring being located on a surface of another portion of the second porous graphite barrel away from the bottom of the crucible; a second graphite paper, the second graphite paper being located on a side of the second porous graphite barrel away from the bottom of the crucible and being supported on a surface of the graphite gasket; The seed crystal is located on the surface of the second graphite paper close to the bottom of the crucible and has a third distance between it and the graphite backing ring; An annular seed crystal pressing block is located on one side of the inner surface of the annular seed crystal holder, is pressed on the surface of the second graphite paper, and is located above the graphite gasket ring.

8. The silicon carbide crystal growth device according to claim 7, characterized in that: The seed crystal assembly also satisfies at least one of the following conditions: The distance between the seed crystal and the graphite block is 30 to 35 mm; The surface of the second porous graphite barrel away from the crucible bottom includes a first surface area and a second surface area, the first surface area is in contact with the annular seed crystal holder, the second surface area is in contact with the graphite backing ring, and the first surface area and the second surface area are not on the same surface; The third spacing is 0.1 to 0.15 mm.

9. The silicon carbide crystal growth device according to claim 5 or 7, characterized in that: The annular seed crystal holder is fitted with the annular seed crystal pressing block, and a fitting gap between the annular seed crystal holder and the annular seed crystal pressing block is less than or equal to 0.2 mm.

10. The silicon carbide crystal growth apparatus according to any one of claims 1 to 8, characterized in that: Also includes: A soft graphite felt is arranged on the surface of the crucible bottom in the first porous graphite barrel.

11. The silicon carbide crystal growth apparatus according to any one of claims 1 to 8, characterized in that: The graphite block holder and the seed crystal ring are connected via threads.

12. The silicon carbide crystal growth apparatus according to any one of claims 1 to 8, characterized in that: Also includes: a graphite sheet, the graphite sheet being arranged on a side of the seed crystal assembly away from the bottom of the crucible; a first thermal insulation felt disposed between the graphite sheet and the crucible cover; A temperature measuring hole passes through the first thermal insulation felt and the crucible cover, and an orthographic projection of the temperature measuring hole in the vertical direction is located within the orthographic projection of the seed crystal in the vertical direction.

13. The silicon carbide crystal growth device according to claim 12, characterized in that: Also includes: a second thermal insulation felt, which is arranged on the outside of the crucible and has a through hole communicating with the temperature measuring hole; A storage platform, comprising a carrier and a tray placed on the carrier, the tray being used to place the crucible; a quartz tube having a sealed chamber for placing the crucible; An induction coil is arranged outside the quartz tube and is used for heating.

Images