Device system and method for reducing carbon wrappage in crystal
By providing a multi-layer filter layer combination and a hollow guide layer in the silicon carbide crystal growth device, the problem of carbon wrap generation is solved, the crystal quality is improved and the cost is reduced.
Patent Information
- Application Number
- CN202411286753.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-13
- Publication Date
- 2025-01-07
AI Technical Summary
In the prior art, there is a high carbon wrap during the growth of silicon carbide crystals, resulting in high dislocation density and defects, affecting device performance, and the existing filtration methods are costly and inefficient.
A multi-layer longitudinal and transverse filter layer combination is arranged in the silicon carbide crystal growth device, and combined with a hollow guide layer, multiple gas filtration is realized to reduce the generation and transmission of carbon particles.
It significantly reduces the generation of carbon encapsulation, reduces the carbon particles generated by corrosion of graphite devices, improves crystal quality, and reduces the need to use high-cost air conduction rings.
Smart Images
Figure CN119265692A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of crystal growth, and relates to a device system for crystal growth, and in particular to a device system and method for reducing carbon inclusions in crystals. Background Art
[0002] Silicon carbide (SiC) is a representative wide bandgap semiconductor material. Due to its superior semiconductor properties, silicon carbide is widely used in the manufacture of high-temperature, high-frequency and high-power electronic devices. At present, the mainstream method for producing silicon carbide crystals is the physical vapor transport method (PVT method). In recent years, people have made great progress in expanding the diameter of silicon carbide crystals and reducing polymorphic inclusions. However, the produced silicon carbide crystals still have some defects that cannot be ignored, such as high dislocation density and carbon inclusions. Among them, carbon inclusions can induce defects such as micropipes and stacking faults. The presence of these defects will seriously weaken the quality of the silicon carbide substrate, thereby affecting the performance of silicon carbide-based semiconductor devices.
[0003] There are two main sources of carbon inclusions in silicon carbide crystals: carbon particles transported with gas after graphitization of powder and carbon particles produced by corrosion of graphite devices by silicon-rich gas. Porous graphite plates are often used to filter carbon particles transported with gas after graphitization of powder. However, the filtering effect of carbon particles in the gas using only a single layer of porous graphite plates is not good, and in the early stage of silicon carbide crystal growth, graphite devices such as porous graphite plates and gas guide rings will be corroded by silicon-rich gas to produce carbon particles. Chemical vapor deposition (CVD) of tantalum carbide on these graphite devices can effectively prevent the graphite devices from being corroded and producing carbon particles. However, the cost of CVD is relatively high, and different reaction gas flow ratios, reaction pressures, and reaction times will affect the ability of tantalum carbide coatings to resist gas corrosion.
[0004] It can be seen that how to effectively reduce the carbon particles transmitted with the gas after the powder is graphitized during physical vapor transmission and the carbon particles generated by the corrosion of graphite devices by silicon-rich gas has become an urgent problem that technical personnel in this field need to solve. Summary of the invention
[0005] The object of the present invention is to provide a device system and method for reducing carbon inclusions in crystals. The device system effectively reduces the carbon particles transmitted with the gas after the powder is graphitized during physical vapor transmission, and avoids the carbon particles generated by the corrosion of graphite devices by silicon-rich gas, thereby effectively reducing the carbon inclusions in the crystals.
[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:
[0007] In a first aspect, the present invention provides a device system for reducing carbon inclusions in crystals, the device system comprising a crucible and a filter layer group and a hollow guide layer disposed inside the crucible.
[0008] The filter layer group includes at least two longitudinal filter layers and at least one transverse filter layer.
[0009] Among them, the number of layers of the longitudinal filter layer is at least 2 layers, for example, it can be 2 layers, 3 layers, 4 layers, 5 layers or 6 layers, and 2 layers are more preferred. The number of layers of the transverse filter layer is at least 1 layer, for example, it can be 1 layer, 2 layers, 3 layers, 4 layers or 5 layers, and 1 layer is more preferred, but it is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0010] The device system provided by the present invention sets a filter layer group inside the crucible, and further limits the filter layer group to include a longitudinal filter layer and a transverse filter layer, so that the gas is subjected to multiple longitudinal filtration and transverse filtration in sequence during the transmission process, thereby significantly reducing the carbon particles in the gas, and further effectively reducing the carbon inclusions in the crystals.
[0011] In addition, the setting of the hollow guide layer can guide the gas after multiple filtration directly to the seed crystal from the middle, without the use of an air guide ring, thereby reducing the economic cost of graphite air guide rings or air guide rings with tantalum carbide coatings, and avoiding carbon particles generated by corrosion of graphite air guide rings.
[0012] Preferably, the longitudinal filter layer comprises a mesh filter layer and / or a fibrous filter layer.
[0013] Preferably, the material of the longitudinal filter layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them. Typical but non-limiting combinations include a combination of tantalum carbide and tungsten carbide, a combination of tungsten carbide and niobium carbide, a combination of tantalum carbide and niobium carbide, or a combination of tantalum carbide, tungsten carbide and niobium carbide, and tantalum carbide is further preferred.
[0014] Preferably, the longitudinal filter layer is a mesh filter layer, and the average diameter of the mesh holes in the mesh filter layer is 5-300 μm, for example, it can be 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0015] In the present invention, the mesh size of the mesh filter layer needs to be limited to a reasonable range. Specifically, when its average diameter is less than 5 μm, the mesh is easily blocked by carbon particles during physical gas phase transmission, thereby inhibiting the smooth transmission of gas to the seed crystal; when its average diameter is greater than 300 μm, the carbon particles in the gas are difficult to be fully filtered, resulting in a significant reduction in filtration efficiency.
[0016] Preferably, the distance between the longitudinal filter layer and the adjacent longitudinal filter layer is 10-20 cm, for example, it can be 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm or 20 cm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0017] Preferably, the transverse filter layer includes any one of a pleated filter layer, a granular filter layer or a powdered filter layer, or a combination of at least two of them. Typical but non-limiting combinations include a combination of a pleated filter layer and a granular filter layer, a combination of a granular filter layer and a powdered filter layer, a combination of a pleated filter layer and a powdered filter layer, or a combination of a pleated filter layer, a granular filter layer and a powdered filter layer, and a pleated filter layer is further preferred.
[0018] Preferably, the material of the transverse filter layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them. Typical but non-limiting combinations include a combination of tantalum carbide and tungsten carbide, a combination of tungsten carbide and niobium carbide, a combination of tantalum carbide and niobium carbide, or a combination of tantalum carbide, tungsten carbide and niobium carbide, and tantalum carbide is further preferred.
[0019] Preferably, the layer height of the transverse filter layer is 6-10 mm, for example, it can be 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm or 10 mm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0020] Preferably, the average diameter of the mesh in the pleated filter layer is 5-300 μm, for example, it can be 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0021] The present invention adopts a pleated filter layer with the same mesh size as the mesh filter layer as the transverse filter layer, which not only significantly increases the filter area, but also the pleated shape can filter the transversely transmitted gas multiple times, thereby further improving the filtering effect.
[0022] Preferably, the average particle size of the particles in the granular filter layer is 0.5-6 mm, for example, it can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm or 6 mm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0023] Preferably, the average particle size of the powder in the powdered filter layer is 10-500 μm, for example, it can be 10 μm, 20 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0024] Preferably, the shape of the hollow area of the hollow guide layer includes any one of circular, square or triangular.
[0025] Preferably, the material of the hollow guide layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them. Typical but non-limiting combinations include a combination of tantalum carbide and tungsten carbide, a combination of tungsten carbide and niobium carbide, a combination of tantalum carbide and niobium carbide, or a combination of tantalum carbide, tungsten carbide and niobium carbide, and tantalum carbide is further preferred.
[0026] In the present invention, the materials of the longitudinal filter layer, the transverse filter layer and the hollow guide layer are independently selected from any one of tantalum carbide, tungsten carbide or niobium carbide or a combination of at least two of them. Such materials have extremely strong corrosion resistance, will not produce carbon particles due to self-corrosion, and can be reused many times.
[0027] Preferably, the hollow shape of the hollow guide layer is circular, and the diameter of the circle is 40-200 mm, for example, it can be 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm or 200 mm, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0028] In a second aspect, the present invention provides a method for reducing carbon inclusions in a crystal using the device system as described in the first aspect, the method comprising the following steps:
[0029] (1) loading a silicon carbide raw material into the bottom of a crucible, and heating the crucible to a first temperature within a first time period, wherein the silicon carbide raw material is sublimated into a gas after being heated;
[0030] (2) The sublimated gas rises to the filter layer group and is filtered longitudinally and transversely in sequence;
[0031] (3) Part of the gas after longitudinal filtration is deposited as polycrystalline silicon carbide on the surface of the hollow guide layer, and the remaining gas passes through the hollow area of the hollow guide layer after transverse filtration and is deposited as single crystal silicon carbide on the surface of the seed crystal;
[0032] (4) When the crucible is heated to the second temperature, the polycrystalline silicon carbide deposited on the surface of the hollow guide layer begins to sublime into gas, and the gas passes through the hollow area of the hollow guide layer after being laterally filtered, and is deposited as single crystal silicon carbide on the surface of the seed crystal;
[0033] (5) The crucible is kept at the second temperature for a second period of time, the silicon carbide raw material continues to be heated and sublimated, and no polycrystalline silicon carbide is deposited on the surface of the hollow guide layer.
[0034] Preferably, the deposition thickness of the polycrystalline silicon carbide in step (3) is ≤10 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, and the deposition area is ≤80 cm 2 , for example, it can be 5cm 2 , 10cm 2 、15cm 2 , 20cm 2 、25cm 2 、30cm 2 、35cm 2 、40cm 2 、45cm 2 , 50cm 2 、55cm 2 、60cm 2 、65cm 2 、70cm 2 、75cm 2 or 80cm 2 , but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0035] Preferably, the first temperature is 2000-2300°C, for example, it can be 2000°C, 2050°C, 2100°C, 2150°C, 2200°C, 2250°C or 2300°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0036] Preferably, the first time period is 10-15 hours, for example, it can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0037] Preferably, the second temperature is 2200-2500°C, for example, it can be 2200°C, 2250°C, 2300°C, 2350°C, 2400°C, 2450°C or 2500°C, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0038] Preferably, the second time period is 100-200h, for example, it can be 100h, 110h, 120h, 130h, 140h, 150h, 160h, 170h, 180h, 190h or 200h, but is not limited to the listed values, and other unlisted values within the numerical range are also applicable.
[0039] The numerical range described in the present invention not only includes the point values listed above, but also includes any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values included in the range.
[0040] Compared with the prior art, the present invention has the following beneficial effects:
[0041] (1) The device system provided by the present invention sets a filter layer group inside the crucible, and further defines the filter layer group to include a longitudinal filter layer and a transverse filter layer, so that the gas is subjected to multiple longitudinal filtration and transverse filtration in sequence during the transmission process, thereby significantly reducing the carbon particles in the gas, and further effectively reducing the carbon inclusions in the crystals.
[0042] (2) The setting of the hollow guide layer can guide the gas after multiple filtration directly to the seed crystal from the middle, without the need for a gas guide ring, thereby reducing the economic cost of the graphite gas guide ring or the gas guide ring with tantalum carbide coating, and avoiding the carbon particles generated by the corrosion of the graphite gas guide ring. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Figure 1 is a schematic diagram of the structure of the device system for reducing carbon inclusions in crystals provided in Examples 1-3;
[0044] Figure 2 It is a schematic diagram of the pleated filter layer structure in the device system provided in Examples 1-3.
[0045] Wherein: 10-crucible; 11-silicon carbide raw material; 12-seed crystal; 20-filter layer group; 21-longitudinal filter layer; 22-transverse filter layer; 30-hollow guide layer. DETAILED DESCRIPTION
[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.
[0047] Example 1
[0048] This embodiment provides a device system and method for reducing carbon inclusions in crystals, such as Figure 1 As shown, the device system includes a crucible 10 and a filter layer group 20 and a hollow guide layer 30 disposed inside the crucible 10 . The filter layer group 20 includes two longitudinal filter layers 21 and one transverse filter layer 22 .
[0049] In this embodiment, the longitudinal filter layer 21 is a mesh filter layer made of tantalum carbide, and the average diameter of the mesh holes in the mesh filter layer is 100 μm, and the distance between adjacent mesh filter layers is 15 cm; the transverse filter layer 22 is a folded filter layer made of tantalum carbide (see Figure 2 ), and the layer height of the pleated filter layer is 8 mm, and the average diameter of the mesh is 100 μm; the material of the hollow guide layer 30 is tantalum carbide, the shape of the hollow area is circular, and the diameter of the circle is 60 mm.
[0050] The method of reducing carbon inclusions in crystals using the above-mentioned device system in this embodiment includes the following steps:
[0051] (1) loading a silicon carbide raw material 11 into the bottom of a crucible 10, and heating the crucible 10 to 2200° C. within 12 hours, wherein the silicon carbide raw material 11 is sublimated into a gas after being heated;
[0052] (2) The sublimated gas rises to the filter layer group 20 and is filtered longitudinally and transversely in sequence;
[0053] (3) After longitudinal filtration, part of the gas is deposited as polycrystalline silicon carbide on the surface of the hollow guide layer 30, and the deposition thickness of the polycrystalline silicon carbide is 8 mm and the deposition area is 60 cm 2 , the remaining gas passes through the hollow area of the hollow guide layer 30 after being filtered horizontally, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0054] (4) When the crucible 10 is heated to 2400° C., the polycrystalline silicon carbide deposited on the surface of the hollow guide layer 30 begins to sublimate into gas, and the gas passes through the hollow area of the hollow guide layer 30 after being laterally filtered, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0055] (5) The crucible 10 is kept at 2400° C. for 150 h, the silicon carbide raw material 11 is continuously heated and sublimated, and no polycrystalline silicon carbide is deposited on the surface of the hollow guide layer 30 .
[0056] Example 2
[0057] This embodiment provides a device system and method for reducing carbon inclusions in crystals, such as Figure 1 As shown, the device system includes a crucible 10 and a filter layer group 20 and a hollow guide layer 30 disposed inside the crucible 10 . The filter layer group 20 includes two longitudinal filter layers 21 and one transverse filter layer 22 .
[0058] In this embodiment, the longitudinal filter layer 21 is a mesh filter layer made of tungsten carbide, and the average diameter of the mesh holes in the mesh filter layer is 30 μm, and the distance between adjacent mesh filter layers is 10 cm; the transverse filter layer 22 is a folded filter layer made of tungsten carbide (see Figure 2 ), and the layer height of the pleated filter layer is 6 mm, and the average diameter of the mesh is 30 μm; the material of the hollow guide layer 30 is tungsten carbide, the shape of the hollow area is circular, and the diameter of the circle is 40 mm.
[0059] The method of reducing carbon inclusions in crystals using the above-mentioned device system in this embodiment includes the following steps:
[0060] (1) loading a silicon carbide raw material 11 into the bottom of a crucible 10, and heating the crucible 10 to 2000° C. within 15 hours, wherein the silicon carbide raw material 11 is sublimated into a gas after being heated;
[0061] (2) The sublimated gas rises to the filter layer group 20 and is filtered longitudinally and transversely in sequence;
[0062] (3) After longitudinal filtration, part of the gas is deposited on the surface of the hollow guide layer 30 as polycrystalline silicon carbide, and the deposition thickness of the polycrystalline silicon carbide is 10 mm and the deposition area is 80 cm 2 , the remaining gas passes through the hollow area of the hollow guide layer 30 after being filtered horizontally, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0063] (4) When the crucible 10 is heated to 2200° C., the polycrystalline silicon carbide deposited on the surface of the hollow guide layer 30 begins to sublimate into gas, and the gas passes through the hollow area of the hollow guide layer 30 after being laterally filtered, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0064] (5) The crucible 10 is kept at 2200° C. for 200 h, the silicon carbide raw material 11 is continuously heated and sublimated, and no polycrystalline silicon carbide is deposited on the surface of the hollow guide layer 30 .
[0065] Example 3
[0066] This embodiment provides a device system and method for reducing carbon inclusions in crystals, such as Figure 1As shown, the device system includes a crucible 10 and a filter layer group 20 and a hollow guide layer 30 disposed inside the crucible 10 . The filter layer group 20 includes two longitudinal filter layers 21 and one transverse filter layer 22 .
[0067] In this embodiment, the longitudinal filter layer 21 is a mesh filter layer made of niobium carbide, and the average diameter of the mesh holes in the mesh filter layer is 300 μm, and the distance between adjacent mesh filter layers is 20 cm; the transverse filter layer 22 is a folded filter layer made of niobium carbide (see Figure 2 ), and the layer height of the pleated filter layer is 10 mm, and the average diameter of the mesh is 300 μm; the material of the hollow guide layer 30 is niobium carbide, the shape of the hollow area is circular, and the diameter of the circle is 80 mm.
[0068] The method of reducing carbon inclusions in crystals using the above-mentioned device system in this embodiment includes the following steps:
[0069] (1) loading a silicon carbide raw material 11 into the bottom of a crucible 10, and heating the crucible 10 to 2300° C. within 10 hours, wherein the silicon carbide raw material 11 is sublimated into a gas after being heated;
[0070] (2) The sublimated gas rises to the filter layer group 20 and is filtered longitudinally and transversely in sequence;
[0071] (3) After longitudinal filtration, part of the gas is deposited on the surface of the hollow guide layer 30 as polycrystalline silicon carbide, and the deposition thickness of the polycrystalline silicon carbide is 8 mm and the deposition area is 65 cm 2 , the remaining gas passes through the hollow area of the hollow guide layer 30 after being filtered horizontally, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0072] (4) When the crucible 10 is heated to 2500° C., the polycrystalline silicon carbide deposited on the surface of the hollow guide layer 30 begins to sublimate into gas, and the gas passes through the hollow area of the hollow guide layer 30 after being laterally filtered, and is deposited as single crystal silicon carbide on the surface of the seed crystal 12;
[0073] (5) The crucible 10 is kept at 2500° C. for 100 h, the silicon carbide raw material 11 is continuously heated and sublimated, and no polycrystalline silicon carbide is deposited on the surface of the hollow guide layer 30 .
[0074] Example 4
[0075] This embodiment provides a device system and method for reducing carbon inclusions in crystals. Except that the transverse filter layer 22 is changed to a granular filter layer made of tantalum carbide and the average particle size of the particles is 4 mm, the rest of the structure and conditions are the same as those in Example 1 and will not be described in detail here.
[0076] Example 5
[0077] The present embodiment provides a device system and method for reducing carbon inclusions in crystals. Except that the transverse filter layer 22 is changed to a powder filter layer made of tantalum carbide and the average particle size of the powder is 500 μm, the rest of the structure and conditions are the same as those in Example 1 and will not be described in detail here.
[0078] Example 6
[0079] This embodiment provides a device system and method for reducing carbon inclusions in crystals. Except for changing the longitudinal filter layer 21 to a fibrous filter layer made of tantalum carbide, the remaining structures and conditions are the same as those in Embodiment 1, so they are not described here.
[0080] Example 7
[0081] This embodiment provides a device system and method for reducing carbon inclusions in crystals. Except that the shape of the hollow area of the hollow guide layer 30 is changed to a square, and the diameter of the circumscribed equivalent circle of the square is 60 mm, the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.
[0082] Example 8
[0083] This embodiment provides a device system and method for reducing carbon inclusions in crystals. Except that the shape of the hollow area of the hollow guide layer 30 is changed to a triangle, and the diameter of the circumscribed equivalent circle of the triangle is 60 mm, the rest of the structure and conditions are the same as those in Example 1, so they are not repeated here.
[0084] Example 9
[0085] This embodiment provides a device system and method for reducing carbon inclusions in crystals. Except for changing the number of longitudinal filter layers 21 to 3 and the number of transverse filter layers 22 to 2, the rest of the structure and conditions are the same as those in Embodiment 1, so they will not be elaborated here.
[0086] Comparative Example 1
[0087] This comparative example provides a device system and method for reducing carbon inclusions in crystals. Except for directly removing the transverse filter layer 22 and retaining only the longitudinal filter layer 21, the remaining structures and conditions are the same as those in Example 1, so they are not described here in detail.
[0088] Comparative Example 2
[0089] This comparative example provides a device system and method for reducing carbon inclusions in crystals. Except for directly removing the longitudinal filter layer 21 and retaining only the transverse filter layer 22, the remaining structures and conditions are the same as those in Example 1, so they are not described here in detail.
[0090] Upon testing, the silicon carbide crystals obtained in Examples 1-9 had no carbon inclusions, and had very few defects such as microtubes and stacking faults, while the silicon carbide crystals obtained in Comparative Examples 1-2 had obvious carbon inclusions, and defects such as microtubes and stacking faults were more significant.
[0091] It can be seen that the device system provided by the present invention sets a filter layer group inside the crucible, and further limits the filter layer group to include a longitudinal filter layer and a transverse filter layer, so that the gas is subjected to multiple longitudinal filtration and transverse filtration in sequence during the transmission process, thereby significantly reducing the carbon particles in the gas, and then effectively reducing the carbon inclusions in the crystals.
[0092] In addition, the setting of the hollow guide layer can guide the gas after multiple filtration directly to the seed crystal from the middle, without the use of an air guide ring, thereby reducing the economic cost of graphite air guide rings or air guide rings with tantalum carbide coatings, and avoiding carbon particles generated by corrosion of graphite air guide rings.
[0093] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.
Claims
1. A device system for reducing carbon inclusions in crystals, characterized in that: The device system comprises a crucible and a filter layer group and a hollow guide layer arranged inside the crucible; The filter layer group includes at least two longitudinal filter layers and at least one transverse filter layer.
2. The device system according to claim 1, characterized in that: The longitudinal filter layer includes a mesh filter layer and / or a fibrous filter layer; The material of the longitudinal filter layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them.
3. The device system according to claim 2, characterized in that: The longitudinal filter layer is a mesh filter layer, and the average diameter of the mesh holes in the mesh filter layer is 5-300 μm; The distance between the longitudinal filter layer and the adjacent longitudinal filter layer is 10-20 cm.
4. The device system according to claim 1, characterized in that: The transverse filter layer includes any one of a pleated filter layer, a granular filter layer or a powder filter layer, or a combination of at least two of them; The material of the transverse filter layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them.
5. The device system according to claim 4, characterized in that: The layer height of the transverse filter layer is 6-10 mm; The average diameter of the mesh in the pleated filter layer is 5-300 μm; The average particle size of the particles in the granular filter layer is 0.5-6 mm; The average particle size of the powder in the powdery filter layer is 10-500 μm.
6. The device system according to claim 1, characterized in that: The shape of the hollow area of the hollow guide layer includes any one of a circle, a square or a triangle; The material of the hollow guide layer includes any one of tantalum carbide, tungsten carbide or niobium carbide, or a combination of at least two of them.
7. The device system according to claim 6, characterized in that: The hollow shape of the hollow guide layer is circular, and the diameter of the circle is 40-200 mm.
8. A method for reducing carbon inclusions in crystals using the device system as claimed in any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) loading a silicon carbide raw material into the bottom of a crucible, and heating the crucible to a first temperature within a first time period, wherein the silicon carbide raw material is sublimated into a gas after being heated; (2) The sublimated gas rises to the filter layer group and is filtered longitudinally and transversely in sequence; (3) Part of the gas after longitudinal filtration is deposited as polycrystalline silicon carbide on the surface of the hollow guide layer, and the remaining gas passes through the hollow area of the hollow guide layer after transverse filtration and is deposited as single crystal silicon carbide on the surface of the seed crystal; (4) When the crucible is heated to the second temperature, the polycrystalline silicon carbide deposited on the surface of the hollow guide layer begins to sublime into gas, and the gas passes through the hollow area of the hollow guide layer after being laterally filtered, and is deposited as single crystal silicon carbide on the surface of the seed crystal; (5) The crucible is kept at the second temperature for a second period of time, the silicon carbide raw material continues to be heated and sublimated, and no polycrystalline silicon carbide is deposited on the surface of the hollow guide layer.
9. The method according to claim 8, characterized in that The deposition thickness of the polycrystalline silicon carbide in step (3) is ≤10 mm and the deposition area is ≤80 cm 2 .
10. The method according to claim 8, characterized in that The first temperature is 2000-2300° C., and the first time period is 10-15 hours; the second temperature is 2200-2500° C., and the second time period is 100-200 hours.