Preparation method and preparation device of silicon carbide epitaxial wafer

Abstract

The invention provides a preparation method and a preparation device of a silicon carbide epitaxial wafer. The preparation method comprises the following steps: providing a substrate, and placing the substrate in an epitaxial reaction cavity; the substrate is heated, the distance between the substrate and a heating heat source is controlled to be H mm, and the reaction temperature in the epitaxial reaction cavity is T DEG C; introducing carrier gas, a growth source and a doping source, and preparing an epitaxial layer on the surface of the substrate to obtain a silicon carbide epitaxial wafer; wherein the distance H mm and the reaction temperature T DEG C meet the condition that (T-1500) / H is larger than or equal to 5.5 and smaller than or equal to 7. By controlling the distance between the substrate and a heating heat source, the airflow and the temperature field on the surface of the substrate are adjusted, the temperature difference between the center and the edge of the wafer is reduced, and the triangular defects on the surface of the wafer are reduced; meanwhile, the distance between the substrate and the heating heat source is matched with the temperature in the epitaxial reaction cavity, the growth rate of the epitaxial layer can be ensured, triangular defects are reduced, meanwhile, step defects are avoided, and therefore the overall quality of the epitaxial wafer is improved.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor manufacturing technology, and specifically relates to a method and a device for preparing a silicon carbide epitaxial wafer. Background Art

[0002] Silicon carbide (SiC) is a new type of semiconductor material. Compared with silicon wafers, silicon carbide has a larger bandwidth and higher thermal conductivity, enabling it to work in high-frequency and high-power applications. This makes silicon carbide wafers have broad application prospects in fields such as wireless communications, radar systems, and power transmission. However, despite major breakthroughs and rapid development of SiC technology, the poor surface quality of its epitaxial layer and high preparation cost are two major factors limiting the industrialization of SiC. At present, defects such as triangular defects, drips, and carrots in SiC epitaxial layers are considered to be fatal defects. For example, the triangular defects in the epitaxial layer can reduce the breakdown voltage of electronic devices such as JBS, SBD, MOSFET, BJT, IGBT, etc. by about 50%-90%.

[0003] The existing process can control the triangular defects by increasing the temperature. As the temperature increases, the gas phase nucleation of silicon is suppressed, thereby reducing the number of triangular defects on the surface of the epitaxial layer. However, as the temperature increases, step defects will appear on the surface of the epitaxial layer. The aggregation of step defects will increase the leakage current in the Schottky diode, resulting in a decrease in the breakdown voltage. Summary of the invention

[0004] The present invention provides a method and a device for preparing a silicon carbide epitaxial wafer, aiming to solve the problem of triangle defects and step defects occurring during the growth process of the existing silicon carbide epitaxial wafer.

[0005] The first embodiment of the present application provides a method for preparing a silicon carbide epitaxial wafer, comprising the following steps:

[0006] Providing a substrate, and placing the substrate in an epitaxial reaction chamber;

[0007] The substrate is heated, and a distance H mm is controlled between the substrate and a heating source, and a reaction temperature T° C. is set in the epitaxial reaction chamber;

[0008] Passing a carrier gas, a growth source and a doping source to prepare an epitaxial layer on the surface of the substrate to obtain the silicon carbide epitaxial wafer;

[0009] Wherein, the distance H mm and the reaction temperature T°C satisfy:

[0010] 5.5≤(T-1500) / H≤7.

[0011] In some embodiments, the carrier gas has a first flow rate Q1 slm, satisfying:

[0012] 1680≤H·Q1≤2570.

[0013] In some embodiments, the growth source has a second flow rate Q2 sccm, and the doping source has a third flow rate Q3 sccm, satisfying:

[0014] Q1: Q2: Q3=1~1.5: 1~5: 0.5~4.

[0015] In some embodiments, the distance H mm further satisfies: 16.8≤H≤19.8.

[0016] In some embodiments, the reaction temperature T°C further satisfies: 1580≤T≤1640.

[0017] In some embodiments, the first flow rate Q1 slm further satisfies: 100≤Q1≤130.

[0018] In some embodiments, the second flow rate Q2 slm further satisfies: 120≤Q2≤470.

[0019] In some embodiments, the third flow rate Q3 slm further satisfies: 50≤Q3≤400.

[0020] In some embodiments, the carrier gas includes hydrogen.

[0021] In some embodiments, the growth source includes a carbon source and a silicon source.

[0022] In some embodiments, the doping source includes a nitrogen source.

[0023] In some embodiments, the flow ratio of the carbon source to the silicon source is 1-3:2-9.

[0024] In some embodiments, the carbon source includes at least one of ethylene and propane.

[0025] In some embodiments, the silicon source includes at least one of trimethylsilyl chloride and silane.

[0026] In some embodiments, the nitrogen source includes at least one of ammonia and nitrogen.

[0027] In some embodiments, the step of introducing a carrier gas, a growth source, and a doping source further comprises:

[0028] Pass inert gas;

[0029] Wherein, the flow rate of the inert gas is 0.5-1.0 slm.

[0030] In some embodiments, in the step of preparing an epitaxial layer on the substrate surface, the pressure in the epitaxial reaction chamber is 80-100 mbar.

[0031] A second embodiment of the present application provides a device for preparing a silicon carbide epitaxial wafer, which is used to implement the method for preparing a silicon carbide epitaxial wafer in any of the above embodiments, including:

[0032] A carrying portion, used for carrying a substrate;

[0033] The heating part is used to heat the substrate. The heating part is located on a side of the supporting part away from the substrate and is detachably connected to the supporting part.

[0034] In some embodiments, the device for preparing a silicon carbide epitaxial wafer further includes a connecting portion;

[0035] The bearing portion is provided with a first placement groove, the heating portion is provided with a second placement groove corresponding to the first placement groove, and the connecting portion is simultaneously arranged in the first placement groove and the second placement groove.

[0036] In some embodiments, along the thickness direction of the supporting portion, there is a first dimension D between a side of the connecting portion close to the substrate and a side of the supporting portion away from the substrate, satisfying: 5.75 mm≤D≤5.95 mm.

[0037] The present application provides a method for preparing a silicon carbide epitaxial wafer, comprising the following steps: providing a substrate, placing the substrate in an epitaxial reaction chamber; heating the substrate, controlling the distance H mm between the substrate and the heated heat source, and the reaction temperature T°C in the epitaxial reaction chamber; introducing a carrier gas, a growth source, and a doping source, preparing an epitaxial layer on the surface of the substrate, and obtaining a silicon carbide epitaxial wafer; wherein the distance H mm and the reaction temperature T°C satisfy: 5.5≤(T-1500) / H≤7. By controlling the distance between the substrate and the heated heat source, the airflow and temperature field on the surface of the substrate are adjusted, the temperature difference between the center and the edge of the wafer is reduced, thereby reducing the triangular defects on the surface of the wafer; at the same time, the distance between the substrate and the heated heat source is coordinated with the temperature in the epitaxial reaction chamber, which can ensure the growth rate of the epitaxial layer and reduce the triangular defects while avoiding the appearance of step defects, thereby improving the overall quality of the epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0039] Figure 1 A flow chart of a method for preparing a silicon carbide epitaxial wafer provided in an embodiment of the present application;

[0040] Figure 2A structural diagram of a device for preparing a silicon carbide epitaxial wafer provided in an embodiment of the present application;

[0041] Figure 3 Schematic diagram of triangular defects on the surface of epitaxial wafer;

[0042] Figure 4 A graph showing the surface defect test results of silicon carbide epitaxial wafers provided in the embodiments and comparative examples of the present application;

[0043] Reference numerals:

[0044] 10 -carrying part, 11 -first placement groove, 20 -heating part, 21 -second placement groove, 30 -connecting part, 100 -substrate, 200 -epitaxial layer. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0046] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0047] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application.

[0048] The first embodiment of the present application provides a method for preparing a silicon carbide epitaxial wafer, such as Figure 1 As shown, the following steps are included:

[0049] S1, providing a substrate 100, and placing the substrate 100 in an epitaxial reaction chamber;

[0050] S2, heating the substrate 100, controlling the distance H mm between the substrate 100 and the heating source, and the reaction temperature T°C in the epitaxial reaction chamber;

[0051] S3, introducing a carrier gas, a growth source and a doping source to prepare an epitaxial layer 200 on the surface of the substrate 100 to obtain a silicon carbide epitaxial wafer.

[0052] Among them, the distance H mm and the reaction temperature T℃ satisfy:

[0053] 5.5≤(T-1500) / H≤7.

[0054] It is understandable that the value of (T-1500) / H can be any value among 5.5, 6.0, 6.5, 7.0 or a range between any two values. By counting the length, width and height of the epitaxial wafer triangle defect in different regions of the wafer, such as Figure 3 As shown, it can be seen that the triangle in the center of the epitaxial wafer has a longer tail and a more regular edge. This is due to the temperature difference between the center and the edge. The difference in the edge ring airflow causes the edge temperature to be low, and its triangular defects are more regular. For the triangle in the center, the temperature is higher and the growth rate is faster, which causes the growth rate of 3C-SiC to accelerate in the height direction, resulting in longer boundaries of 3C-SiC and 4H-SiC. The distance between the substrate 100 and the heated heat source will affect the temperature field on the surface of the substrate 100, and thus affect the formation of triangular defects on the surface of the epitaxial wafer. By controlling the distance between the substrate and the heated heat source, the airflow and temperature field on the surface of the substrate are adjusted, and the temperature difference between the center and the edge of the wafer is reduced, thereby reducing triangular defects on the surface of the wafer; at the same time, the distance between the substrate and the heated heat source is combined with the temperature in the epitaxial reaction chamber, which can ensure the growth rate of the epitaxial layer and reduce triangular defects while avoiding the appearance of step defects, thereby improving the overall quality of the epitaxial wafer.

[0055] In some embodiments, the carrier gas has a first flow rate Q1 slm, satisfying:

[0056] 1680≤H·Q1≤2570.

[0057] It can be understood that the value of the product of the distance H between the substrate 100 and the heated heat source and the first flow rate Q1 (unit: mm·slm) can be any value among 1680, 1830, 1980, 2130, 2280, 2430, 2570 or a range between any two values. The triangular defects in the epitaxial wafer are mostly caused by the dropped objects during the growth of the epitaxial layer. When the etching carrier gas flow is large, it is easy for the loose silicon carbide particles in the cavity to fall on the tray, and when the carrier gas flow is small, it may cause the growth rate of the epitaxial layer 200 to be too slow, and the etching effect is not in place, causing surface defects; in addition, the distance between the substrate 100 and the heated heat source will affect the airflow on the surface of the substrate 100. When the distance H mm and the flow rate of the carrier gas meet the above relationship, it can ensure that the final epitaxial wafer has fewer defects.

[0058] In some embodiments, the growth source has a second flow rate Q2 sccm, and the doping source has a third flow rate Q3 sccm, satisfying:

[0059] Q1: Q2: Q3=1~1.5: 1~5: 0.5~4.

[0060] It is understandable that during the growth of the silicon carbide epitaxial wafer, the carrier gas can also act as a dilution gas to adjust the pressure in the epitaxial reaction chamber. At the same time, the ratio of the carrier gas, the growth source and the doping source in the epitaxial reaction chamber will also affect the competitive relationship between C and N on the surface of the epitaxial layer 200; and even if the C / N ratio is maintained at the same, the amount of hydrogen acting as a dilution gas and a carrier will also affect the exhaustion effect of the growth and doping gases along the way, which will further affect the C / Si ratio and the N ratio on the surface of the actual epitaxial layer 200, and at the same time affect the growth rate of the epitaxial layer 200. Therefore, when the flow rate ratio of the carrier gas, the growth source and the doping source satisfies the above relationship, it can ensure that the finally formed silicon carbide epitaxial wafer has ideal doping uniformity and good surface quality.

[0061] In some embodiments, the distance H mm further satisfies: 16.8≤H≤19.8.

[0062] It can be understood that the value of the distance H (unit: mm) can be any value among 16.8, 17.3, 17.8, 18.3, 18.8, 19.3, 19.8 or a range between any two values. When the distance H mm between the substrate 100 and the heating heat source satisfies the above value range, the airflow and temperature field on the surface of the substrate 100 can be further adjusted, and the temperature difference between the center and the edge of the wafer can be reduced, thereby reducing the triangular defects on the wafer surface.

[0063] In some embodiments, the reaction temperature T°C further satisfies: 1580≤T≤1640. It is understood that the value of the reaction temperature T (unit: °C) can be any value among 1580, 1600, 1620, 1640 or a range between any two values.

[0064] In some embodiments, the first flow rate Q1 slm further satisfies: 100≤Q1≤130. It can be understood that the value of the first flow rate Q1 (unit: slm) can be any value among 100, 110, 120, 130 or a range between any two values.

[0065] In some embodiments, the second flow rate Q2 slm further satisfies: 120≤Q2≤470. It can be understood that the value of the second flow rate Q2 (unit: slm) can be any value of 120, 200, 300, 400, 470 or a range between any two values.

[0066] In some embodiments, the third flow rate Q3 slm further satisfies: 50≤Q3≤400. It can be understood that the value of the third flow rate Q3 (unit: slm) can be any value of 50, 100, 200, 300, 400 or a range between any two values.

[0067] When the reaction temperature T°C, the first flow rate Q1 slm, the second flow rate Q2 slm, and the third flow rate Q3 slm satisfy the above value ranges, the lattice structure inside the silicon carbide epitaxial wafer can be further optimized, while reducing defects such as triangular defects on the outer surface.

[0068] In some embodiments, the carrier gas includes hydrogen.

[0069] In some embodiments, the growth source includes a carbon source and a silicon source.

[0070] In some embodiments, the doping source includes a nitrogen source.

[0071] In some embodiments, the flow ratio of the carbon source to the silicon source is 1-3:2-9.

[0072] It can be understood that the flow ratio of the carbon source and the silicon source can be any value of 1:2, 1:3, 2:5, 3:8, 1:9 or a range between any two values. When the flow ratio of the carbon source and the silicon source meets the above range of values, it can control the integrity of the crystal structure in the silicon carbide epitaxial wafer, while ensuring that the epitaxial layer 200 has a reasonable growth rate and avoiding the occurrence of triangular defects and step defects.

[0073] In some embodiments, the carbon source includes at least one of ethylene and propane.

[0074] In some embodiments, the silicon source includes at least one of trimethylsilyl chloride and silane.

[0075] In some embodiments, the nitrogen source includes at least one of ammonia and nitrogen.

[0076] In some embodiments, the step of introducing a carrier gas, a growth source, and a doping source further comprises:

[0077] Pass inert gas;

[0078] The flow rate of the inert gas is 0.5 to 1.0 slm.

[0079] It is understood that the flow rate of the inert gas (unit: slm) can be any value among 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or a range between any two values. The inert gas can be used as a diluent gas to further adjust the pressure in the epitaxial reaction chamber, thereby regulating the growth rate of the epitaxial layer 200 and reducing the generation of triangle defects and step defects.

[0080] In some embodiments, the inert gas may be argon.

[0081] In some embodiments, in the step of preparing an epitaxial layer on the surface of the substrate 100, the pressure in the epitaxial reaction chamber is 80-100 mbar.

[0082] It is understandable that the value of the pressure in the epitaxial reaction chamber (unit: mbar) can be any value among 80, 85, 90, 95, 100 or a range between any two values. When the pressure in the epitaxial reaction chamber meets the above value range, the epitaxial layer 200 has an ideal growth rate and reduces the generation of triangle defects and step defects.

[0083] The second embodiment of the present application provides a device for preparing a silicon carbide epitaxial wafer, which is used to implement the method for preparing a silicon carbide epitaxial wafer in any of the above embodiments, such as Figure 2 As shown, including:

[0084] The carrying part 10 is used for carrying the substrate 100;

[0085] The heating part 20 is used to heat the substrate 100 . The heating part 20 is located on a side of the carrier part 10 away from the substrate 100 , and is detachably connected to the carrier part 10 .

[0086] Based on the above embodiments, Figure 2As shown, the bearing part 10 may include an air floating tray and a graphite tray, and the edge of the heating part 20 is provided with an annular boss to form a groove, so that the bearing part 10 can be detachably embedded in the groove of the heating part 20. When the carrier gas flow is introduced into the epitaxial chamber, the gas flow flows into the groove between the bearing part 10 and the heating part 20, suspending the air floating tray on the top of the heating part 20 and causing the air floating tray to rotate.

[0087] In some embodiments, Figure 2 As shown, the device for preparing silicon carbide epitaxial wafer further includes a connecting portion 30;

[0088] The bearing portion 10 is provided with a first placement groove 11 , the heating portion 20 is provided with a second placement groove 21 corresponding to the first placement groove 11 , and the connecting portion 30 is disposed in both the first placement groove 11 and the second placement groove 21 .

[0089] The connection part 30 can further fix the bearing part 10 . When the carrier gas flows into the epitaxial chamber, the connection part 30 can stabilize the relative position of the bearing part 10 and the heating part 20 during the rotation process without deviation.

[0090] In some embodiments, along the thickness direction of the carrier 10 , a first dimension D is present between a side of the connection portion 30 close to the substrate 100 and a side of the carrier 10 far from the substrate 100 , satisfying: 5.75 mm≤D≤5.95 mm.

[0091] It can be understood that the value of the first dimension D (unit: mm) can be any value between 5.75, 5.8, 5.85, 5.9, and 5.95 or a range between any two values. When the exposed height of the connecting portion 30 relative to the heating portion 20 is too high, it is easy to cause the lifting position of the bearing portion 10 to be too high, the thermal field is affected by the heating, the temperature difference between the edge and the center is large, and the low temperature is not conducive to the triangular transformation. At the same time, it will also cause the bearing portion 10 to be unstable during the rotation process, offset, contact and friction with the connecting portion 30 to cause carbon powder overflow, and the connecting portion 30 to wear, which is not conducive to the stability of growth, and may even cause the connecting portion 30 to break; and when the exposed height of the connecting portion 30 relative to the heating portion 20 is too low, it will cause the lifting position of the bearing portion 10 to be too low, the distance between the bearing portion 10 and the heating portion 20 is too close, and it is easy to contact the base to generate friction, which will also cause carbon powder to overflow, affecting the particle size in the epitaxial reaction chamber, and at the same time, it will cause the bearing portion 10 to rotate unsteadily, affecting the film thickness and doping uniformity of the epitaxial layer 200. Therefore, when the first dimension D satisfies the above value range, it can ensure that the connection portion 30 has a reasonable exposure height, thereby controlling the epitaxial wafer to have fewer triangular defects and good thickness and doping uniformity.

[0092] The following is a description of the method and device for preparing a silicon carbide epitaxial wafer provided by the present application in conjunction with specific embodiments:

[0093] Example 1

[0094] This embodiment provides a device and method for preparing a silicon carbide epitaxial wafer, wherein the preparation device is as follows: Figure 2 As shown, including:

[0095] The carrying part 10 is used to carry the substrate 100, and the carrying part 10 is provided with a first placement groove 11;

[0096] The heating part 20 is used to heat the substrate 100 . The heating part 20 is located on a side of the carrying part 10 away from the substrate 100 and is detachably connected to the carrying part 10 . The heating part 20 is provided with a second placement groove 21 corresponding to the first placement groove 11 .

[0097] The connecting portion 30 is disposed in both the first placement groove 11 and the second placement groove 21 .

[0098] The connecting portion 30 has a first size D=5.75 mm.

[0099] The silicon carbide epitaxial wafer is prepared by the above-mentioned preparation device, such as Figure 1 As shown, the specific steps include:

[0100] S1, providing a substrate 100, and placing the substrate 100 in an epitaxial reaction chamber;

[0101] S2, heating the substrate 100, controlling the distance H between the substrate 100 and the heating source to be 18 mm, and the reaction temperature T in the epitaxial reaction chamber to be 1610° C.;

[0102] S3, introducing a carrier gas, a growth source and a doping source to prepare an epitaxial layer 200 on the surface of the substrate 100 to obtain a silicon carbide epitaxial wafer.

[0103] Example 2

[0104] The silicon carbide epitaxial wafer preparation device and preparation method provided in Example 2 are the same as those in Example 1, with the only difference being the use of another epitaxial reaction chamber and the adjustment of the first dimension D, corresponding to the change in the distance H between the substrate 100 and the heating source.

[0105] Embodiment 3-4

[0106] The silicon carbide epitaxial wafer preparation apparatus and preparation method provided in Examples 3 to 4 are the same as those in Example 2, except for the adjustment of process parameters and the first dimension D, and the change of the distance H between the corresponding substrate 100 and the heating source.

[0107] Comparative Examples 1-2

[0108] The preparation device and preparation method of the silicon carbide epitaxial wafer provided in Comparative Examples 1 to 2 are the same as those in Examples 1 to 4, except that the process parameters and the first dimension D are adjusted, corresponding to the change in the distance H between the substrate 100 and the heating source.

[0109] Comparative Examples 3-4

[0110] The preparation apparatus and preparation method of the silicon carbide epitaxial wafer provided in Comparative Examples 3 to 4 are the same as those in Examples 1 to 4, and the only difference is the adjustment of the process parameters and the first dimension D, and the change of the distance H between the corresponding substrate 100 and the heating source.

[0111] The relevant process parameters of Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] The surface defects of the epitaxial wafers prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were scanned and counted using a surface defect tester (Candela 8520). The results are as follows: Figure 4 shown.

[0116] according to Figure 4 It can be seen that the triangular defects on the surface of the epitaxial wafer prepared by the solution provided in the present application are significantly reduced.

[0117] The above is a detailed introduction to a method and device for preparing a silicon carbide epitaxial wafer provided in the embodiments of the present application. Specific examples are used in the present application to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a silicon carbide epitaxial wafer, characterized in that: The steps include: Providing a substrate (100), and placing the substrate (100) in an epitaxial reaction chamber; The substrate (100) is heated, and a distance H mm is controlled between the substrate (100) and a heating source, and a reaction temperature T°C is maintained in the epitaxial reaction chamber; Passing a carrier gas, a growth source and a doping source to prepare an epitaxial layer (200) on the surface of the substrate (100) to obtain the silicon carbide epitaxial wafer; Wherein, the distance H mm and the reaction temperature T°C satisfy: 5.5≤(T-1500) / H≤7.

2. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: The carrier gas has a first flow rate Q1 slm, satisfying: 1680≤H·Q1≤2570.

3. The method for preparing a silicon carbide epitaxial wafer according to claim 2, characterized in that: The growth source has a second flow rate Q2 sccm, and the doping source has a third flow rate Q3 sccm, satisfying: Q1: Q2: Q3=1~1.5: 1~5: 0.5~4.

4. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: The distance H mm further satisfies: 16.8≤H≤19.

8.

5. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: The reaction temperature T°C further satisfies: 1580≤T≤1640.

6. The method for preparing a silicon carbide epitaxial wafer according to claim 3, characterized in that: The first flow rate Q1 slm further satisfies: 100≤Q1≤130; and / or, The second flow rate Q2 slm further satisfies: 120≤Q2≤470; and / or, The third flow rate Q3 slm further satisfies: 50≤Q3≤400.

7. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: The carrier gas comprises hydrogen; and / or, The growth source comprises a carbon source and a silicon source; and / or, The doping source includes a nitrogen source.

8. The method for preparing a silicon carbide epitaxial wafer according to claim 7, characterized in that: The flow ratio of the carbon source to the silicon source is 1-3:2-9.

9. The method for preparing a silicon carbide epitaxial wafer according to claim 7, characterized in that: The carbon source comprises at least one of ethylene and propane; and / or, The silicon source comprises at least one of trimethylsilyl chloride and silane; and / or, The nitrogen source includes at least one of ammonia and nitrogen.

10. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: The step of introducing a carrier gas, a growth source and a doping source further comprises: Pass inert gas; Wherein, the flow rate of the inert gas is 0.5-1.0 slm.

11. The method for preparing a silicon carbide epitaxial wafer according to claim 1, characterized in that: In the step of preparing an epitaxial layer on the surface of the substrate (100), the pressure in the epitaxial reaction chamber is 80-100 mbar.

12. A device for preparing a silicon carbide epitaxial wafer, used for implementing the method for preparing a silicon carbide epitaxial wafer according to any one of claims 1 to 11, characterized in that: include: A carrying portion (10) for carrying a substrate (100); A heating portion (20) is used to heat the substrate (100); the heating portion (20) is located on a side of the supporting portion (10) away from the substrate (100) and is detachably connected to the supporting portion (10).

13. The device for preparing a silicon carbide epitaxial wafer according to claim 12, characterized in that: Also includes a connecting portion (30); The bearing portion (10) is provided with a first placement groove (11), the heating portion (20) is provided with a second placement groove (21) corresponding to the first placement groove (11), and the connecting portion (30) is simultaneously arranged in the first placement groove (11) and the second placement groove (21).

14. The device for preparing a silicon carbide epitaxial wafer according to claim 13, characterized in that: Along the thickness direction of the bearing portion (10), there is a first dimension D between a side of the connecting portion (30) close to the substrate (100) and a side of the bearing portion (10) away from the substrate (100), satisfying: 5.75 mm ≤ D ≤ 5.95 mm.

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