Silicon carbide epitaxial wafer and growth method thereof

Abstract

The invention provides a silicon carbide epitaxial wafer and a growth method thereof. The growth method comprises the following steps: loading a silicon carbide substrate into a growth chamber of an epitaxial furnace; adjusting the epitaxial growth temperature in the growth chamber and the carbon-silicon ratio of a carbon source to a silicon source, and growing an epitaxial layer with a target specification on the silicon carbide substrate; wherein the ratio of the epitaxial growth temperature to the carbon-silicon ratio is defined as a temperature-silicon ratio and is represented by W, and 1700 < = W < = 2300, so that the technical problem of poor thickness uniformity of the silicon carbide epitaxial layer can be improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor epitaxial technology, and in particular to a silicon carbide epitaxial wafer and its growth method. Background Technology

[0002] Silicon carbide, as a representative of third-generation semiconductors, possesses numerous material advantages such as high temperature resistance, high pressure resistance, and fast conversion efficiency, making silicon carbide epitaxial growth a current research hotspot in the industry. Currently, the industry primarily uses silicon carbide epitaxial furnaces for homogeneous epitaxial growth of silicon carbide substrates. Horizontal epitaxial furnaces are widely used due to their relatively simple equipment structure and low cost.

[0003] Many factors affect the quality of silicon carbide epitaxial wafers, such as surface defects, epitaxial layer concentration uniformity, and epitaxial layer thickness uniformity. Poor epitaxial layer thickness uniformity can affect device consistency, repeatability, and ultimately reduce device yield. Although the process of homogeneous epitaxial growth using horizontal silicon carbide epitaxial furnaces is relatively mature, there is still significant room for improvement in optimizing the thickness uniformity of the epitaxial layer. Conventional methods for optimizing thickness uniformity, such as adjusting the carbon-to-silicon ratio and adjusting the source gas flow rate in different regions of the reaction chamber, can improve epitaxial layer thickness uniformity to some extent, but the effect is minimal. Summary of the Invention

[0004] This invention provides a method for growing silicon carbide epitaxial wafers to improve the technical problem of poor thickness uniformity of silicon carbide epitaxial layers.

[0005] This invention provides a method for growing silicon carbide epitaxial wafers, comprising the following steps: loading a silicon carbide substrate into the growth chamber of an epitaxial furnace; adjusting the epitaxial growth temperature within the growth chamber and the carbon-to-silicon ratio of the carbon source to the silicon source, and growing an epitaxial layer of a target size on the silicon carbide substrate; wherein, the ratio of the epitaxial growth temperature to the carbon-to-silicon ratio is defined as the temperature-to-silicon ratio, denoted by W.

[0006] 1700≤W≤2300.

[0007] In one embodiment of the present invention, the epitaxial growth temperature is T, wherein 1560℃≤T≤1650℃.

[0008] In one embodiment of the present invention, the carbon-silicon ratio is I, wherein 0.7 ≤ I ≤ 0.95.

[0009] In one embodiment of the present invention, the epitaxial furnace further includes a first gas vent, a second gas vent, a third gas vent, and a tail gas treatment device. One end of the first gas vent and one end of the second gas vent are connected and simultaneously connected to a gas source. The other end of the first gas vent is connected to the growth chamber. The other end of the second gas vent is connected to the tail gas treatment device. The two ends of the third gas vent are respectively connected to the growth chamber and the tail gas treatment device.

[0010] In one embodiment of the present invention, after loading the silicon carbide substrate into the growth chamber of the epitaxial furnace, the following steps are further included: hydrogen etching of the silicon carbide substrate; growing a silicon carbide buffer layer on the etched silicon carbide substrate; wherein, the pressure value of the first vent pipe is P1, the pressure value of the second vent pipe is P2, P1 and P2 are defined as the pressure ratio, denoted by E, and E is adjusted to 1.2≤E≤1.8.

[0011] In one embodiment of the present invention, 450mbar≤P1≤800mbar.

[0012] In one embodiment of the present invention, 250mbar≤P2≤670mbar.

[0013] In one embodiment of the present invention, at least three branch pipes are further provided between the first ventilation pipe and the growth chamber. One end of each branch pipe is connected to the first ventilation pipe, and the other end of each branch pipe away from the first ventilation pipe is connected to the growth chamber. The growth chamber is provided with a plurality of air inlets corresponding to and connected to the plurality of branch pipes. At least one air inlet is directly opposite to the center of the silicon carbide substrate placement position, and the other plurality of air inlets are arranged in a centrally symmetrical manner with respect to the center. Each branch pipe is provided with a valve.

[0014] In one embodiment of the present invention, the pressure value P1 of the first vent pipe is adjusted by the valves provided on the plurality of branch pipes.

[0015] The present invention also provides a silicon carbide epitaxial wafer, which is prepared according to the above-described silicon carbide epitaxial wafer growth method.

[0016] The beneficial effects of this invention: The silicon carbide epitaxial wafer growth method proposed in this invention achieves a silicon carbide temperature-to-temperature ratio (W / W ratio) of 1700 ≤ W ≤ 2300 by adjusting the epitaxial growth temperature and the carbon-to-silicon ratio of the gas introduced into the growth chamber. In existing technologies, adjusting only the carbon-to-silicon ratio or only the growth temperature can change the thickness of the epitaxial layer; however, both methods have minimal effect on improving thickness uniformity. This invention, by simultaneously adjusting the carbon-to-silicon ratio and the growth temperature, and ensuring 1700 ≤ W ≤ 2300, can improve the uniformity of the silicon carbide epitaxial layer thickness. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] In the attached diagram:

[0019] Figure 1 This is a flowchart of a method for growing silicon carbide epitaxial wafers according to an embodiment of the present invention;

[0020] Figure 2 This is a point diagram for measuring the thickness of the epitaxial layer on a sample provided in one embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the flow and pressure distribution of the reaction gas in an epitaxial furnace provided in one embodiment of the present invention;

[0022] Figure 4 This is a comparative example 1 epitaxial layer thickness distribution trend diagram provided in one embodiment of the present invention;

[0023] Figure 5 This is a trend diagram of epitaxial layer thickness distribution in Embodiment 1 of the present invention;

[0024] Figure 6 This is a trend diagram of epitaxial layer thickness distribution in Embodiment 2 of the present invention;

[0025] Figure 7 This is a trend diagram of epitaxial layer thickness distribution in Embodiment 3 of the present invention;

[0026] Figure 8 This is a comparative example 2 epitaxial layer thickness distribution trend diagram provided in one embodiment of the present invention;

[0027] Figure 9 This is a schematic diagram of the internal structure of a silicon carbide epitaxial wafer provided in one embodiment of the present invention.

[0028] The attached figures are labeled as follows:

[0029] 100, Growth chamber; 200, First ventilation duct; 300, Second ventilation duct; 400, Third ventilation duct; 500, Exhaust gas treatment device; 600, Epitaxial wafer; 610, Substrate; 620, Buffer layer; 630, Epitaxial layer. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0031] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0032] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0033] Please see Figure 1 , Figure 1 This is a flowchart of a method for growing a silicon carbide epitaxial wafer 600. This method can achieve targeted control of the thickness distribution trend of the epitaxial layer 630, thereby effectively improving the thickness uniformity of the silicon carbide epitaxial layer 630 and ultimately improving the quality of the silicon carbide epitaxial wafer 600.

[0034] The growth method includes the following steps:

[0035] S1. The silicon carbide substrate 610 is loaded into the growth chamber 100 of the epitaxial furnace.

[0036] S2. Adjust the epitaxial growth temperature in the growth chamber 100 and the carbon-silicon ratio of the carbon source to the silicon source to grow an epitaxial layer 630 of the target size on the silicon carbide substrate 610.

[0037] The ratio of the epitaxial growth temperature to the carbon-silicon ratio is defined as the temperature-silicon ratio, denoted by W, where 1700≤W≤2300.

[0038] In this embodiment, firstly, a silicon carbide substrate 610 is loaded into the growth chamber 100 of the epitaxial furnace and placed on the base of the growth chamber 100 for subsequent epitaxial growth. Secondly, the epitaxial growth temperature and the carbon-silicon ratio of the carbon source to the silicon source are simultaneously adjusted within the growth chamber 100 to ensure that the temperature-silicon ratio W satisfies 1700 ≤ W ≤ 2300. This allows for the growth of an epitaxial layer 630 of the target specifications on the silicon carbide substrate 610. It should be noted that the temperature-silicon ratio is the ratio of the epitaxial growth temperature to the carbon-silicon ratio. The carbon-silicon ratio is the ratio of the molar flow rate of the carbon source gas to the molar flow rate of the silicon source gas in the reaction gas introduced into the growth chamber 100. In the prior art, simply adjusting the carbon-silicon ratio can change the thickness of the epitaxial layer 630; specifically, simply increasing the carbon-silicon ratio increases the thickness of the epitaxial layer 630, and vice versa. Simply adjusting the growth temperature can alter the thickness of the epitaxial layer 630. Specifically, increasing the growth temperature increases the thickness of the epitaxial layer 630, while decreasing it decreases it. Although both methods can change the thickness of the epitaxial layer 630, their effect on improving thickness uniformity is minimal. However, this invention, by simultaneously adjusting the carbon-silicon ratio and the growth temperature, ensuring 1700 ≤ W ≤ 2300, can improve the uniformity of the silicon carbide epitaxial layer 630's thickness and ultimately enhance the quality of the silicon carbide epitaxial wafer 600.

[0039] In one embodiment of the present invention, the epitaxial growth temperature is T, wherein 1560℃≤T≤1650℃. When the temperature is below 1560℃, the growth rate is too slow, resulting in low production efficiency. When the temperature is above 1650℃, the growth rate is too fast; although this can increase production capacity, it makes it difficult to control the thickness uniformity of the epitaxial layer 630 and easily introduces defects.

[0040] In one embodiment of the present invention, the carbon-to-silicon ratio is I, where 0.7 ≤ I ≤ 0.95. By precisely limiting the carbon-to-silicon ratio I to the range of 0.7 to 0.95, and forming a synergistic constraint with the growth temperature of 1560–1650 °C and the temperature-to-silicon ratio of 1700–2300 °C, the generation of defects such as silicon droplets and carbon inclusions is reduced. At the high temperature of 1560–1650 °C, surface atoms have high migration ability, and the carbon-to-silicon ratio of 0.7–0.95 provides the optimal proportion of adsorbed atoms. All of these abilities are conducive to obtaining a smooth surface morphology. This improves the uniformity of the thickness of the silicon carbide epitaxial layer 630 and ultimately enhances the quality of the silicon carbide epitaxial wafer 600.

[0041] Please see Figure 3In one embodiment of the present invention, the epitaxial furnace further includes a first ventilation pipe 200, a second ventilation pipe 300, a third ventilation pipe 400, and a tail gas treatment device 500. One end of the first ventilation pipe 200 and one end of the second ventilation pipe 300 are connected to a gas source. The other end of the first ventilation pipe 200 is connected to the growth chamber 100. The other end of the second ventilation pipe 300 is connected to the tail gas treatment device 500. The two ends of the third ventilation pipe 400 are respectively connected to the growth chamber 100 and the tail gas treatment device 500.

[0042] Please see Figure 3 In this embodiment, the first ventilation pipe 200 leads to the growth chamber 100, and the second ventilation pipe 300 leads directly to the exhaust gas treatment device 500, both sharing the same gas source. By adjusting the flow control valves on the first and second ventilation pipes 200 and 300, the total airflow can be precisely divided, like a distributor, into a portion entering the growth chamber 100 and a portion being directly discharged. This ensures that the total flow rate from the gas source remains constant, mitigating pressure fluctuations and flow oscillations caused by adjusting a single downstream valve. A stable source airflow is a prerequisite for stable growth.

[0043] In one embodiment of the present invention, after the silicon carbide substrate 610 is loaded into the growth chamber 100 of the epitaxial furnace, the following step is further included:

[0044] The silicon carbide substrate 610 is etched with hydrogen to clean and repair its surface, providing a smoother surface for the subsequent growth of the epitaxial layer 630, thereby improving the flatness of the epitaxial layer 630.

[0045] A silicon carbide buffer layer 620 is grown on the etched silicon carbide substrate 610. Typically, the surface of the substrate 610 is not perfectly flat at the atomic scale. The buffer layer 620 can fill tiny surface depressions and cover protrusions, thereby forming a new surface that is flatter and more uniform than the original substrate 610 surface, further providing a flatter surface for the growth of the epitaxial layer 630.

[0046] Before the silicon carbide buffer layer 620 is grown on the etched silicon carbide substrate 610, no carbon or silicon source is needed. The carbon and silicon sources are discharged into the exhaust gas treatment device 500 through the second vent pipe 300. When the buffer layer 620 begins to grow and the epitaxial layer 630 is grown on the buffer layer 620, carbon and silicon sources are required. Therefore, at the instant the growth of the buffer layer 620 begins, the carbon and silicon sources are instantly transferred from the second vent pipe 300 to the first vent pipe 200. This instantaneous change in the content of carbon and silicon sources in the first vent pipe 200 causes an imbalance in the carbon-to-silicon ratio in the growth chamber 100, affecting the thickness uniformity of the epitaxial layer 630.

[0047] Especially during the mass production of silicon carbide epitaxial wafers 600, each silicon carbide substrate 610 experiences a sudden change in the carbon and silicon source content in the first venting channel 200 the instant the buffer layer 620 begins to grow after etching. Each imbalance in the carbon-to-silicon ratio affects the thickness uniformity of the epitaxial layer 630, impacting the efficiency and quality of mass production. In this embodiment, the pressure value of the first venting channel 200 is P1, and the pressure value of the second venting channel 300 is P2. P1 and P2 are defined as the pressure ratio, denoted by E, and E is adjusted to 1.2 ≤ E ≤ 1.8. This setting allows for a smooth distribution and transfer of carbon and silicon source flow rates between the two paths, rather than a sudden flow rate change like a switch. This mitigates the sudden change in carbon and silicon source content when switching from the second venting channel 300 to the first venting channel 200, helping to maintain a constant carbon-to-silicon ratio and reducing the impact on the thickness uniformity of the silicon carbide epitaxial layer 630. This will improve the processing efficiency and quality of silicon carbide epitaxial wafers during mass production.

[0048] In one embodiment of the present invention, 450 mbar ≤ P1 ≤ 800 mbar. P1 > 800 mbar may result in an excessively fast growth rate and difficulty in controlling uniformity; P1 < 450 mbar, on the other hand, the pressure is too low, resulting in a slow growth rate and low efficiency.

[0049] In one embodiment of the present invention, 250 mbar ≤ P2 ≤ 670 mbar. The range of P2 works in conjunction with the range of P1 to match the control range of the pressure ratio E. This ensures that the pressure ratio E is achievable and controllable throughout the entire operating range.

[0050] Please see Figure 3In one embodiment of the present invention, at least three branch pipes (not shown in the figure) are further provided between the first ventilation pipe 200 and the growth chamber 100. One end of each branch pipe is connected to the first ventilation pipe 200, and the other end of each branch pipe away from the first ventilation pipe 200 is connected to the growth chamber 100. The growth chamber 100 is provided with multiple air inlets corresponding to and connected to the multiple branch pipes. At least one air inlet is directly opposite the center of the silicon carbide substrate 610 placement position, i.e., the center of the base. The other multiple air inlets are arranged symmetrically with respect to the center. This uniform arrangement of multiple air inlets ensures a uniform distribution of the reactive gas within the growth chamber 100. Each branch pipe is equipped with a valve to individually control the flow rate of the reactive gas entering each air inlet, achieving precise adjustment. In this embodiment, three branch pipes are provided. One branch pipe is directly opposite the center of the silicon carbide substrate 610 placement position, and the other two branch pipes can be symmetrically arranged with respect to any axis passing through the center, corresponding to both sides of the silicon carbide substrate 610 placement position respectively. This not only provides a more uniform gas distribution, but also improves the uniformity of the epitaxial layer 630 thickness by adjusting the gas flow rate separately.

[0051] Please see Figure 3 In one embodiment of the present invention, the pressure value P1 of the first ventilation pipe 200 is adjusted by the valves installed on the plurality of branch pipes. P1 is determined by the opening degree of the valves on all branch pipes. This setting allows for precise adjustment by changing the flow distribution ratio while keeping the total pressure P1 essentially constant. Preferably, the flow rates of each air inlet and another air inlet symmetrically arranged therewith are adjusted to be equal.

[0052] Please see Figure 9 The present invention also provides a silicon carbide epitaxial wafer 600, which is fabricated according to the above-described growth method for the silicon carbide epitaxial wafer 600. The silicon carbide epitaxial wafer 600 includes a silicon carbide substrate 610, a silicon carbide buffer layer 620 grown on the silicon carbide substrate 610, and a silicon carbide epitaxial layer 630 grown on the silicon carbide buffer layer 620. By employing the above-described growth method, the uniformity of the thickness of the epitaxial wafer 600 is improved.

[0053] The growth method of the silicon carbide epitaxial wafer 600 of this application will be specifically described below with reference to specific embodiments and comparative examples. Embodiments 1 to 3 and Comparative Examples 1 to 2 are silicon carbide epitaxial wafers 600 prepared using the same process conditions. Please refer to Table 1. It should be noted that the thickness of the epitaxial layer 630 is the average thickness of multiple locations on the epitaxial wafer 600, such as... Figure 2As shown, nine points are taken on any diameter of the epitaxial wafer 600, and the thickness (unit: μm) of the epitaxial layer 630 at each point is measured, recorded, and calculated. Furthermore, the uniformity of the epitaxial layer 630 thickness is calculated as follows: (maximum thickness - minimum thickness) / (2 × average thickness) × 100%. The value of the epitaxial layer 630 thickness uniformity is obtained from the above formula.

[0054] Table 1

[0055]

[0056] Please see Figure 4 , Figure 4 This is a graph showing the distribution trend of the 630 epitaxial layer thickness as a function of measurement points in Comparative Example 1. Please refer to Table 1. At this point, the temperature-to-silicon ratio is 1500, the pressure ratio is 1.07, the 630 epitaxial layer thickness is 10.12 mm, and the 630 epitaxial layer thickness uniformity is 2.2%. Figure 4 It can be seen that the thickness of the epitaxial layer 630 is distributed with a thin center and a thick edge, and the thickness uniformity is relatively poor.

[0057] Please see Figure 5 , Figure 5 This is a graph showing the distribution trend of the epitaxial layer 630 thickness as a function of measurement points in Example 1. Referring to Table 1, when the temperature-to-silicon ratio is 1700 and the pressure ratio is 1.20, the uniformity of the epitaxial layer 630 thickness is 1.7%. Figure 5 It can be seen that the thickness of the epitaxial layer 630 still exhibits a distribution that is thinner at the center and thicker at the edges. Compared with Comparative Example 1, it can be seen that the temperature-to-silicon ratio of Example 1 is increased, and the temperature-to-silicon ratio W satisfies 1700≤W≤2300. The pressure ratio is also increased, and it satisfies 1.2≤E≤1.8. It is evident that under the above conditions, the edge thickness of the epitaxial layer 630 shows a decreasing trend, and the uniformity of the thickness of the epitaxial layer 630 shows an improving trend.

[0058] Please see Figure 6 , Figure 6 This is a graph showing the distribution trend of the epitaxial layer 630 thickness as a function of measurement points in Example 2. Referring to Table 1, when the temperature-to-silicon ratio is 2000 and the pressure ratio is 1.50, the uniformity of the epitaxial layer 630 thickness is 0.5%. Figure 6 As can be seen, the thickness of the epitaxial layer 630 still exhibits a distribution that is thinner at the center and thicker at the edges, with a significant improvement in thickness uniformity. Compared to Example 1, Example 2 shows an increase in both the temperature-to-silicon ratio and the pressure ratio, resulting in a greater decrease in the edge thickness of the epitaxial layer 630 and a slight increase in the center thickness, thereby significantly improving the thickness uniformity of the epitaxial layer 630.

[0059] Please see Figure 7 As shown, Figure 7 This is a graph showing the distribution trend of the 630 epitaxial layer thickness of the sample in Example 3 as a function of measurement points. Please refer to Table 1 for the temperature-to-silicon ratio of 2300 and the pressure ratio of 1.8. Figure 7 It can be seen that the thickness of the epitaxial layer 630 is distributed with a thicker center and thinner edges, and the thickness uniformity is significantly increased. Compared with Example 2, it can be seen that as the pressure ratio continues to increase, the thickness of the epitaxial layer 630 at the edges continues to decrease and the thickness at the center continues to increase, which makes the thickness uniformity of the epitaxial layer 630 worse than that of Example 2, but still improved compared with Comparative Example 1.

[0060] Please see Figure 8 , Figure 8 This is a graph showing the distribution trend of the 630 epitaxial layer thickness as a function of measurement points in Comparative Example 2. Please refer to Table 1; when the temperature-to-silicon ratio is 2500 and the pressure ratio is 2.00, the uniformity of the 630 epitaxial layer thickness is 2.5%. Please refer to... Figure 8 The epitaxial layer 630 exhibits a thickness distribution that is thicker at the center and thinner at the edges, resulting in a significant increase in thickness uniformity. Comparing with Example 3, it can be seen that as the temperature-to-silicon ratio and pressure ratio continue to increase, the temperature-to-silicon ratio of 2500 exceeds the maximum range of 1700≤W≤2300, and the pressure ratio of 2.00 exceeds the maximum range of 1.2≤E≤1.8. Consequently, the edge thickness of the epitaxial layer 630 continues to decrease, while the center thickness continues to increase, leading to a gradual deterioration in the thickness uniformity of the epitaxial layer 630.

[0061] This invention proposes a method for growing silicon carbide epitaxial wafers. By adjusting the epitaxial growth temperature and the carbon-to-silicon ratio of the gas introduced into the growth chamber, the silicon-to-temperature ratio is made to satisfy 1700 ≤ W ≤ 2300. In existing technologies, adjusting only the carbon-to-silicon ratio or only the growth temperature can change the thickness of the epitaxial layer; however, both methods have little effect on improving thickness uniformity. This invention, by simultaneously adjusting the carbon-to-silicon ratio and the growth temperature, and ensuring 1700 ≤ W ≤ 2300, can improve the uniformity of the silicon carbide epitaxial layer thickness.

[0062] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for growing a silicon carbide epitaxial wafer, characterized by, The method comprises the following steps: loading a silicon carbide substrate into a growth chamber of an epitaxial furnace; adjusting an epitaxial growth temperature and a carbon-to-silicon ratio (carbon-silicon ratio) in the growth chamber to grow an epitaxial layer of a target specification on the silicon carbide substrate; wherein a ratio of the epitaxial growth temperature to the carbon-silicon ratio is defined as a temperature-to-silicon ratio (W), and 1700≤W≤2300.

2. The method of growing a silicon carbide epitaxial layer according to claim 1, wherein The epitaxial growth temperature is T, wherein 1560℃≤T≤1650℃.

3. The method of growing a silicon carbide epitaxial layer as recited in claim 1, wherein, The carbon-silicon ratio is I, wherein 0.7≤I≤0.

95.

4. The method of growing a silicon carbide epitaxial layer as recited in claim 1, wherein, The epitaxial furnace further comprises a first gas passage, a second gas passage, a third gas passage, and a tail gas treatment device, one end of the first gas passage and one end of the second gas passage are communicated and simultaneously communicated with a gas source, the other end of the first gas passage is communicated with the growth chamber, the other end of the second gas passage is communicated with the tail gas treatment device, and both ends of the third gas passage are respectively communicated with the growth chamber and the tail gas treatment device.

5. The method of growing a silicon carbide epitaxial layer as recited in claim 4, wherein, After the step of loading the silicon carbide substrate into the growth chamber of the epitaxial furnace, the method further comprises the following steps: hydrogen etching the silicon carbide substrate; growing a silicon carbide buffer layer on the etched silicon carbide substrate; wherein a pressure value of the first gas passage is P1, a pressure value of the second gas passage is P2, P1 and P2 are defined as a pressure ratio (E), and E is adjusted to 1.2≤E≤1.

8.

6. The method of growing a silicon carbide epitaxial layer as recited in claim 5, wherein 450mbar≤P1≤800mbar.

7. The method of growing a silicon carbide epitaxial layer as claimed in claim 5, wherein, 250mbar≤P2≤670mbar.

8. The method of growing a silicon carbide epitaxial layer as claimed in claim 5, wherein, The first gas passage and the growth chamber are further provided with at least three branch passages, one end of each of the branch passages is communicated with the first gas passage, and the other end of each of the branch passages away from the first gas passage is communicated with the growth chamber. The growth chamber is provided with a plurality of gas inlets corresponding to the plurality of branch passages, at least one of the gas inlets is directly opposite a center of a placement position of the silicon carbide substrate, and the remaining plurality of gas inlets are arranged in a central symmetry relative to the center. Each of the branch passages is provided with a valve.

9. The method of growing silicon carbide epitaxial wafers according to Claim 8 wherein, The pressure value P1 of the first gas passage is adjusted through the valves provided on the plurality of branch passages.

10. A silicon carbide epitaxial wafer, characterized by, The silicon carbide epitaxial wafer is prepared according to the growth method of any one of claims 1 to 9.

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