Apparatus and method for producing silicon carbide crystal by HTCVD method

Abstract

The application provides a device and a method for preparing silicon carbide crystals by an HTCVD method. The device comprises a crucible and a first chamber and a second chamber arranged in the crucible in sequence along the flow direction of a gas source, and the first chamber and the second chamber are connected through a gas pipeline. The first chamber is sequentially provided with a first gas source pipeline and a first silicon carbide growth area along the flow direction of the gas source. The second chamber is sequentially provided with a second gas source pipeline and a second silicon carbide growth area along the flow direction of the gas source. The device and the method can simultaneously grow single crystal silicon carbide and polycrystalline silicon carbide, increase the utilization rate of gas, reduce the production cost, and avoid the blockage of the exhaust pipeline by tail gas.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide crystal preparation, and relates to an apparatus and method for preparing silicon carbide crystals by HTCVD. Background Technology

[0002] SiC crystal growth methods include physical vapor transport (PVT). Since liquid SiC with a stoichiometric Si:C ratio of 1:1 does not exist at ambient pressure, the melt feedstock method commonly used in silicon crystal growth is not suitable for growing bulk SiC crystals. Instead, sublimation has become the primary choice. In sublimation, SiC powder and a SiC substrate (as a seed crystal) are placed in a graphite crucible, and a temperature gradient is established to slightly increase the temperature on the SiC powder side. The overall temperature is maintained in the range of 2000–2500 °C. This method is now known as the modified Lely method and is widely used in SiC substrate production. The SiC crystal growth process of the modified Lely method is as follows: Figure 1 As shown, in a graphite crucible heated to over 2000℃, SiC powder sublimates into molecular states such as Si2C, SiC2, and Si, and is transported to the surface of the seed crystal. The atoms in these molecular states move on the seed crystal surface and are guided to suitable crystal formation positions, thereby growing bulk SiC single crystals.

[0003] Although sublimation remains a significant method for SiC single crystal preparation, its growth rate is still slower compared to Si single crystal growth methods using molten raw materials. While quality is gradually improving, challenges such as dislocations inevitably exist within the crystal. HTCCVD exhibits several advantages in the growth of bulk SiC crystals. First, the high purity of its raw gas allows for precise control of the C / Si ratio in the gas phase, a crucial growth parameter that significantly impacts defect density. Second, this method enables SiC growth at relatively high speeds, exceeding 1 mm / h. However, HTCCVD also faces some challenges. The large amount of material generated during the reaction easily adheres to the inside of the growth furnace and the exhaust pipes, making equipment maintenance difficult. Simultaneously, the gas-phase reaction in the gas may produce particles, which can be incorporated into the crystal as impurities, affecting its quality.

[0004] The precursor gases in high-temperature chemical vapor deposition (HTCVD) are typically silanes (SiH4) and hydrocarbons, such as C2H4 and C3H8. The reaction temperature of HTCVD is generally 2100–2300 °C. In the heated zone, the gases react to form Si and SiC, which are the raw materials for SiC ingot growth. The temperature in the gas reaction zone is higher than that at the seed crystal; this temperature gradient ensures mass transfer, while the lower temperature allows the gas phase to solidify at the seed crystal. Typical SiC crystal growth pressures and growth rates are 250–300 mbar and 0.3–1.5 mm·h, respectively. -1 The main advantages of HTCVD over PVT are the high purity of the prepared SiC, the controllable Si / C atomic ratio, and the continuity of raw material supply.

[0005] The existing technology can only grow one silicon carbide crystal per crucible. The growth temperature of single-crystal SiC is 2100-2300℃, while the growth temperature of polycrystalline SiC is 1200-1400℃. How to grow single-crystal SiC and polycrystalline SiC at the same time is an urgent problem to be solved. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention provides an apparatus and method for preparing silicon carbide crystals by HTCCVD. This apparatus and method can simultaneously grow single-crystal silicon carbide and polycrystalline silicon carbide, increase gas utilization, reduce production costs, and avoid the blockage of exhaust pipes by exhaust gas.

[0007] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0008] One objective of this invention is to provide an apparatus for preparing silicon carbide crystals by HTCVD. The apparatus includes a crucible and a first chamber and a second chamber disposed inside the crucible and sequentially connected along the gas flow direction. The first chamber and the second chamber are connected by a gas pipeline.

[0009] The first cavity is provided with a first gas source pipeline and a first silicon carbide growth area in sequence along the gas source flow direction.

[0010] The second cavity is provided with a second gas source pipeline and a second silicon carbide growth area in sequence along the gas source flow direction.

[0011] As a preferred technical solution of the present invention, the first gas source pipeline includes a silicon source pipeline and a carbon source pipeline arranged around the silicon source pipeline.

[0012] As a preferred technical solution of the present invention, a first seed crystal is provided in the first silicon carbide growth region, and the first seed crystal is connected to the top of the first cavity through a first seed crystal support component.

[0013] As a preferred technical solution of the present invention, the first seed crystal is a silicon carbide seed crystal.

[0014] As a preferred technical solution of the present invention, an air source inlet is provided at the bottom of the first cavity.

[0015] As a preferred technical solution of the present invention, a second seed crystal is provided in the second silicon carbide growth region, and the second seed crystal is connected to the top of the second cavity through a second seed crystal support component.

[0016] As a preferred embodiment of the present invention, the second seed crystal is a monocrystalline silicon seed crystal.

[0017] A second objective of this invention is to provide a method for preparing silicon carbide crystals using HTCVD, which utilizes the apparatus for preparing silicon carbide crystals using HTCVD provided in the first objective. The method includes:

[0018] The first silicon carbide growth region and the second silicon carbide growth region are heated to the silicon carbide growth temperature independently, respectively.

[0019] Carrier gas, silicon source gas and carbon source gas are introduced, and the carrier gas, silicon source gas and carbon source gas reach the first silicon carbide growth area through the first gas source pipeline to grow single crystal silicon carbide.

[0020] Unreacted silicon source gas and carbon source gas enter the second chamber through the gas pipeline, and reach the second silicon carbide growth region through the second gas source pipeline to carry out polycrystalline silicon carbide growth.

[0021] As a preferred embodiment of the present invention, the flow rate of the carrier gas is 35-50 slm, the flow rate of the silicon source gas is 200-450 sccm, and the flow rate of the carbon source gas is 80-150 sccm.

[0022] As a preferred technical solution of the present invention, the growth temperature of single crystal silicon carbide is 2100-2300℃ and the growth pressure is 200-300mbar.

[0023] The growth temperature of polycrystalline silicon carbide is 1200–1400℃, and the growth pressure is 200–300 mbar.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] This invention provides an apparatus and method for preparing silicon carbide crystals by HTCVD. The apparatus and method can grow single-crystal silicon carbide and polycrystalline silicon carbide simultaneously, increasing gas utilization, reducing production costs, and avoiding the blockage of exhaust pipes by exhaust gas. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the apparatus for preparing silicon carbide crystals by HTCVD provided by the present invention.

[0027] Figure 2 This is a schematic diagram of the apparatus for preparing silicon carbide crystals by HTCVD method provided in Comparative Example 1 of the present invention.

[0028] Figure 3 The image shows the Raman spectrum of the 4H-SiC crystal prepared in Example 2 of this invention.

[0029] Figure 4 The image shows the Raman spectrum of the 3C-SiC crystal prepared in Example 2 of this invention.

[0030] In the diagram: 26 - upper cover of the reaction chamber, 28 - lower bottom plate of the reaction chamber, 30 - 32-Outer tube wall, 34-Inner tube wall, 36-Carbon source pipeline, 38-Silicon source pipeline, 40-Spacer ring, 42-Reaction zone, 44-Seed crystal, 46-Seed crystal support assembly, 48-Graphite rod, 50-Silicon carbide ingot, 52-Carbon source inlet, 54-Silicon source inlet, 8-Graphite crucible.

[0031] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0032] The technical solution of this application will be further described below through specific implementation methods.

[0033] The present invention provides an apparatus for preparing silicon carbide crystals by HTCVD method. The apparatus includes a crucible and a first chamber and a second chamber disposed inside the crucible and connected in sequence along the gas source flow direction. The first chamber and the second chamber are connected by a gas pipeline.

[0034] The first cavity is provided with a first gas source pipeline and a first silicon carbide growth area in sequence along the gas source flow direction.

[0035] The second cavity is provided with a second gas source pipeline and a second silicon carbide growth area in sequence along the gas source flow direction.

[0036] In this invention, a higher temperature is set in the first chamber. After the gas source decomposes and reacts at this higher temperature, single-crystal silicon carbide is grown in the first silicon carbide growth region. The unreacted gas source enters the second chamber through a gas pipeline. The first chamber is set at a lower temperature, and the unreacted gas source serves as the growth gas source for the second chamber, where polycrystalline silicon carbide is grown in the second silicon carbide growth region. This invention enables the growth of both single-crystal and polycrystalline silicon carbide in the same crucible, while simultaneously improving the utilization rate of the gas source, reducing the gas source content in the exhaust gas, and preventing blockage of the exhaust pipeline.

[0037] In one specific embodiment of the present invention, the crucible in the apparatus for preparing silicon carbide crystals by HTCCVD is a commonly used crucible in the field of silicon carbide preparation, such as a graphite crucible. Its specific material and size can be adjusted according to production needs and scale, and are not further limited here.

[0038] In one specific embodiment of the present invention, an induction coil is provided on the outside of the crucible, and the crucible is heated by using the principle of electromagnetic coupling.

[0039] In one specific embodiment of the present invention, the first gas source pipeline includes a silicon source pipeline and a carbon source pipeline surrounding the silicon source pipeline. That is, the silicon source pipeline and the carbon source pipeline are concentric cylindrical cavities, with the silicon source pipeline in the inner layer and the carbon source pipeline in the outer layer.

[0040] In one specific embodiment of the present invention, a first seed crystal is provided in the first silicon carbide growth region, and the first seed crystal is connected to the top of the first cavity through a first seed crystal support component.

[0041] In one specific embodiment of the present invention, the growth surface of the first seed crystal faces the gas source flow direction, the back side of the first seed crystal is fixed to the first seed crystal support component, the first seed crystal support component is fixed to the top of the first cavity, and the first seed crystal support component is also connected to the first graphite rod.

[0042] In one specific embodiment of the present invention, a gas source reaction zone is provided between the first gas source pipeline and the first silicon carbide growth region.

[0043] In one specific embodiment of the present invention, the first seed crystal is a silicon carbide seed crystal.

[0044] In one specific embodiment of the present invention, an air source inlet is provided at the bottom of the first cavity.

[0045] In one specific embodiment of the present invention, a silicon source inlet is provided at the bottom of the first cavity corresponding to the silicon source pipeline, and a carbon source inlet is provided at the position corresponding to the carbon source pipeline.

[0046] In one specific embodiment of the present invention, a second seed crystal is provided in the second silicon carbide growth region, and the second seed crystal is connected to the top of the second cavity through a second seed crystal support component.

[0047] In one specific embodiment of the present invention, the growth surface of the second seed crystal faces the direction of gas flow, the back side of the second seed crystal is fixed to the second seed crystal support component, the second seed crystal support component is fixed to the top of the second cavity, and the second seed crystal support component is also connected to the second graphite rod.

[0048] In one specific embodiment of the present invention, a gas source reaction zone is provided between the second gas source pipeline and the second silicon carbide growth region.

[0049] In one specific embodiment of the present invention, the second seed crystal is a single-crystal silicon seed crystal.

[0050] In one specific embodiment of the present invention, an exhaust pipe is provided at the top of the second cavity for discharging the carrier gas and unreacted origin from the crucible.

[0051] This invention provides a method for preparing silicon carbide crystals using HTCVD, the method employing the aforementioned apparatus for preparing silicon carbide crystals using HTCVD, and the method comprising:

[0052] The first silicon carbide growth region and the second silicon carbide growth region are heated to the silicon carbide growth temperature independently, respectively.

[0053] Carrier gas, silicon source gas and carbon source gas are introduced, and the carrier gas, silicon source gas and carbon source gas reach the first silicon carbide growth area through the first gas source pipeline to grow single crystal silicon carbide.

[0054] Unreacted silicon source gas and carbon source gas enter the second chamber through the gas pipeline, and reach the second silicon carbide growth region through the second gas source pipeline to carry out polycrystalline silicon carbide growth.

[0055] In one specific embodiment of the present invention, the inside of the crucible is evacuated before heating the first silicon carbide growth region and the second silicon carbide growth region.

[0056] In one specific embodiment of the present invention, the carrier gas, silicon source gas, and carbon source gas are all gases commonly used in the field of silicon carbide preparation, and are not further limited here.

[0057] In one specific embodiment of the present invention, hydrogen is preferably used as the carrier gas.

[0058] In one specific embodiment of the present invention, the silicon source gas is preferably silane and / or monochlorosilane.

[0059] In one specific embodiment of the present invention, the carbon source gas is preferably ethylene and / or propane.

[0060] In one specific embodiment of the present invention, the flow rate of the carrier gas is 35–50 slm, such as 35 slm, 36 slm, 38 slm, 40 slm, 42 slm, 45 slm, 48 slm, or 50 slm; the flow rate of the silicon source gas is 200–450 sccm, such as 200 sccm, 220 sccm, 250 sccm, 280 sccm, 300 sccm, 320 sccm, 350 sccm, 380 sccm, 400 sccm, 420 sccm, or 450 sccm; and the flow rate of the carbon source gas is 80–150 sccm, such as 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm, or 150 sccm, but is not limited to the listed data; other unlisted values ​​within the above ranges are also applicable.

[0061] In one specific embodiment of the present invention, the carrier gas is introduced into the first cavity through the silicon source inlet and the carbon source inlet, and the carrier gas carries the silicon source gas and the carbon source gas to be transported towards the first seed crystal and the second seed crystal.

[0062] In one specific embodiment of the present invention, the growth temperature of single-crystal silicon carbide is 2100-2300℃ and the growth pressure is 200-300mbar.

[0063] In one specific embodiment of the present invention, the growth temperature of polycrystalline silicon carbide is 1200-1400℃ and the growth pressure is 200-300mbar.

[0064] In one specific embodiment of the present invention, the growth time of monocrystalline silicon carbide and polycrystalline silicon carbide is 10 to 15 hours, such as 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed data. Other unlisted values ​​within this range are also applicable.

[0065] In one specific embodiment of the present invention, after growth is completed, the furnace is cooled down, shut down, and the single-crystal silicon carbide and polycrystalline silicon carbide are removed according to the furnace shutdown procedure. The furnace shutdown procedure is the conventional cooling procedure after HTCCVD growth of silicon carbide, and will not be described in detail here.

[0066] In one specific embodiment of the present invention, single-crystal silicon carbide refers to 4H-SiC crystal, and polycrystalline silicon carbide refers to 3C-SiC crystal.

[0067] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0068] Example 1

[0069] This embodiment provides an apparatus for preparing silicon carbide crystals by HTCVD, the structure of which is as follows: Figure 1 As shown, the device includes a graphite crucible 8 and a first chamber and a second chamber disposed inside the crucible;

[0070] The first cavity is provided with a first gas source pipeline and a first silicon carbide growth area in sequence along the gas source flow direction. The first gas source pipeline includes a silicon source pipeline 38 and a carbon source pipeline 36 surrounding the silicon source pipeline. That is, the space surrounded by the inner pipe wall 34 is the silicon source pipeline 38, and the space between the inner pipe wall 34 and the outer pipe wall 32 is the silicon source pipeline 38. A silicon source inlet 54 is provided at the bottom of the first cavity corresponding to the silicon source pipeline 38, and a carbon source inlet 52 is provided corresponding to the carbon source pipeline 36. A seed crystal 44 is provided in the first silicon carbide growth area. The seed crystal 44 is connected to the top of the first cavity through a seed crystal support component 46. The first seed crystal support component 46 is connected to a graphite rod 48. A spacer ring 40 is provided between the first gas source pipeline and the first silicon carbide growth area. The area inside the spacer ring is the gas source reaction area.

[0071] The second chamber is provided with a second gas source pipeline and a second silicon carbide growth region in sequence along the gas source flow direction. The second gas source pipeline is a silicon source pipeline 38, and the outside of the gas source optical path 38 is an outer pipe wall 32. The second silicon carbide growth region is provided with a seed crystal 44, which is connected to the top of the second chamber through a seed crystal support component 46. The seed crystal support component 46 is connected to a graphite rod 48. A spacer ring 40 is provided between the second gas source pipeline and the second silicon carbide growth region. The area inside the spacer ring is a gas source reaction region 42. An exhaust pipe is provided at the top of the second chamber.

[0072] Example 2

[0073] This embodiment provides a method for preparing silicon carbide crystals by HTCVD. The method uses the apparatus for preparing silicon carbide crystals by HTCVD provided in Example 1, and includes:

[0074] The first and second silicon carbide growth regions were evacuated to 3 mbar.

[0075] The first silicon carbide growth region is heated to 2200℃ and the second silicon carbide growth region is heated to 1300℃;

[0076] Carrier gas H2 is introduced through silicon source inlet 54 and carbon source inlet 52 at a flow rate of 45 slm; silicon source gas silane is introduced through silicon source inlet 54 at a flow rate of 300 sccm; carbon source gas ethylene is introduced through carbon source inlet 52 at a flow rate of 120 sccm; the carrier gas H2 carries silicon source gas silane and silicon source gas silane, which pass through silicon source pipeline 38 and carbon source pipeline 36 respectively to reach the reaction region to generate Si and SiC, and then are sent by the carrier gas to the first silicon carbide growth region to grow 4H-silicon carbide crystals at seed crystal 44 (silicon carbide seed crystal) at a growth pressure of 250 mbar;

[0077] Unreacted silicon source gas and carbon source gas enter the second chamber through the gas pipeline, reach the reaction area 42 through the second gas source pipeline, and are then sent to the second silicon carbide growth area by the carrier gas to grow 3C-silicon carbide crystals on the seed crystal 44 (single crystal silicon seed crystal) at a growth pressure of 250 mbar.

[0078] Example 3

[0079] This embodiment provides a method for preparing silicon carbide crystals by HTCVD. The method uses the apparatus for preparing silicon carbide crystals by HTCVD provided in Example 1, and includes:

[0080] The first and second silicon carbide growth regions were evacuated to 3 mbar.

[0081] The first silicon carbide growth region is heated to 2100°C and the second silicon carbide growth region is heated to 1200°C;

[0082] Carrier gas H2 is introduced through silicon source inlet 54 and carbon source inlet 52 at a flow rate of 35 slm; silicon source gas silane is introduced through silicon source inlet 54 at a flow rate of 200 sccm; carbon source gas ethylene is introduced through carbon source inlet 52 at a flow rate of 80 sccm; the carrier gas H2 carries silicon source gas silane and silicon source gas silane, which pass through silicon source pipeline 38 and carbon source pipeline 36 respectively to reach the reaction region to generate Si and SiC, and then are sent by the carrier gas to the first silicon carbide growth region to grow 4H-silicon carbide crystals at seed crystal 44 (silicon carbide seed crystal) at a growth pressure of 200 mbar;

[0083] Unreacted silicon source gas and carbon source gas enter the second chamber through the gas pipeline, reach the reaction area 42 through the second gas source pipeline, and are then sent to the second silicon carbide growth area by the carrier gas to grow 3C-silicon carbide crystals on the seed crystal 44 (single crystal silicon seed crystal) at a growth pressure of 200 mbar.

[0084] Example 4

[0085] This embodiment provides a method for preparing silicon carbide crystals by HTCVD. The method uses the apparatus for preparing silicon carbide crystals by HTCVD provided in Example 1, and includes:

[0086] The first and second silicon carbide growth regions were evacuated to 3 mbar.

[0087] The first silicon carbide growth region is heated to 2300℃ and the second silicon carbide growth region is heated to 1400℃;

[0088] Carrier gas H2 is introduced through silicon source inlet 54 and carbon source inlet 52 at a flow rate of 50 slm; silicon source gas silane is introduced through silicon source inlet 54 at a flow rate of 450 sccm; carbon source gas ethylene is introduced through carbon source inlet 52 at a flow rate of 150 sccm; the carrier gas H2 carries silicon source gas silane and silicon source gas silane, which pass through silicon source pipeline 38 and carbon source pipeline 36 respectively to the reaction region to generate Si and SiC, and then is sent by the carrier gas to the first silicon carbide growth region to grow 4H-silicon carbide crystals on seed crystal 44 (silicon carbide seed crystal) at a growth pressure of 300 mbar;

[0089] Unreacted silicon source gas and carbon source gas enter the second chamber through the gas pipeline, reach the reaction area 42 through the second gas source pipeline, and are then sent to the second silicon carbide growth area by the carrier gas to grow 3C-silicon carbide crystals on the seed crystal 44 (single crystal silicon seed crystal) at a growth pressure of 300mbar.

[0090] Example 5

[0091] In this embodiment, all conditions are the same as in Example 1, except that the silicon source gas is monochlorosilane and the carbon source gas is propane.

[0092] Comparative Example 1

[0093] This comparative example provides an apparatus for preparing silicon carbide crystals using the HTCVD method. The results of this apparatus are as follows: Figure 2 As shown, the device includes a quartz tube and a graphite crucible disposed inside the quartz tube. A gas inlet is provided at the bottom of the graphite crucible for inputting carrier gas, silicon source gas and carbon source gas. A seed crystal is provided at the top of the graphite crucible. The seed crystal is connected to the top of the graphite crucible through a seed crystal support assembly. The seed crystal support assembly is connected to a graphite rod. An exhaust pipe is also provided at the top of the graphite crucible, and the exhaust pipe is located on both sides of the seed crystal support assembly.

[0094] The apparatus was used to grow 4H-silicon carbide crystals, and the growth conditions, carrier gas, silicon source gas, and carbon source gas used were the same as in Example 2.

[0095] Comparative Example 2

[0096] 3C-silicon carbide crystals were grown using the apparatus provided in Comparative Example 1, with the same growth conditions, carrier gas, silicon source gas, and carbon source gas as in Example 2.

[0097] The crystal form of the 4H-SiC crystals and 3C-SiC crystals prepared in Examples 1-5 and Comparative Examples 1 and 2 was tested using Raman spectroscopy. After the silicon carbide crystals were grown, the presence of material deposition inside the exhaust pipe was observed. No material deposition was recorded as Y, and material deposition was recorded as N. The results are shown in Table 1.

[0098] Table 1

[0099] 4H-SiC Raman Spectroscopy 3C-SiC Raman Spectroscopy Exhaust pipe deposition Example 2 <![CDATA[204cm -1 777cm -1 971cm -1 ]]> <![CDATA[796cm -1 972cm -1 ]]> Y Example 3 <![CDATA[204cm -1 777cm -1 971cm -1 ]]> <![CDATA[796cm -1 972cm -1 ]]> Y Example 4 <![CDATA[204cm -1 777cm -1 971cm -1 ]]> <![CDATA[796cm -1 972cm -1 ]]> Y Example 5 <![CDATA[204cm -1 777cm -1 971cm -1 ]]> <![CDATA[796cm -1 972cm -1 ]]> Y Comparative Example 1 <![CDATA[204cm -1 777cm -1 971cm -1 ]]> / N Comparative Example 2 / <![CDATA[796cm -1 972cm -1 ]]> N

[0100] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0101] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0102] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0103] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An apparatus for preparing silicon carbide crystals by HTCVD, characterized in that, The device includes a crucible and a first cavity and a second cavity disposed inside the crucible and connected sequentially along the gas flow direction. The first cavity and the second cavity are connected by a gas pipeline. The first cavity is provided with a first gas source pipeline and a first silicon carbide growth region in sequence along the gas source flow direction; The second cavity is provided with a second gas source pipeline and a second silicon carbide growth area in sequence along the gas source flow direction. The first silicon carbide growth region is used for monocrystalline silicon carbide growth, and the second silicon carbide growth region is used for polycrystalline silicon carbide growth.

2. The apparatus for preparing silicon carbide crystals by HTC VOD according to claim 1, characterized in that, The first gas source pipeline includes a silicon source pipeline and a carbon source pipeline surrounding the silicon source pipeline.

3. The apparatus for preparing silicon carbide crystals by HTCVD according to claim 1, characterized in that, The first silicon carbide growth region is provided with a first seed crystal, and the first seed crystal is connected to the top of the first cavity through a first seed crystal support component.

4. The apparatus for preparing silicon carbide crystals by HTCVD according to claim 3, characterized in that, The first seed crystal is a silicon carbide seed crystal.

5. The apparatus for preparing silicon carbide crystals by HTCCVD according to claim 1, characterized in that, The bottom of the first cavity is provided with an air source inlet.

6. The apparatus for preparing silicon carbide crystals by HTCVD according to claim 1, characterized in that, The second silicon carbide growth region is provided with a second seed crystal, which is connected to the top of the second cavity through a second seed crystal support assembly.

7. The apparatus for preparing silicon carbide crystals by HTCVD according to claim 6, characterized in that, The second seed crystal is a single-crystal silicon seed crystal.

8. A method for preparing silicon carbide crystals by HTCVD, characterized in that, The method uses the apparatus for preparing silicon carbide crystals by the HTCVD method according to any one of claims 1-7, and the method includes: The first silicon carbide growth region and the second silicon carbide growth region are heated to the silicon carbide growth temperature independently, respectively. Carrier gas, silicon source gas, and carbon source gas are introduced, and the carrier gas, silicon source gas, and carbon source gas reach the first silicon carbide growth region through the first gas source pipeline to grow single crystal silicon carbide. Unreacted silicon source gas and carbon source gas enter the second cavity through the gas pipeline, and reach the second silicon carbide growth region through the second gas source pipeline to carry out polycrystalline silicon carbide growth.

9. The method for preparing silicon carbide crystals by HTCVD according to claim 8, characterized in that, The flow rate of the carrier gas is 35~50 slm, the flow rate of the silicon source gas is 200~450 sccm, and the flow rate of the carbon source gas is 80~150 sccm.

10. The method for preparing silicon carbide crystals by HTCVD according to claim 8, characterized in that, The growth temperature of the single-crystal silicon carbide is 2100~2300℃, and the growth pressure is 200~300 mbar. The growth temperature of the polycrystalline silicon carbide is 1200~1400℃, and the growth pressure is 200~300 mbar.

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