Air inlet structure and P-type silicon carbide epitaxial growth device and method

Abstract

The invention relates to the technical field of semiconductor processing, and particularly discloses a gas inlet structure and a P-type silicon carbide epitaxial growth device and method.The gas inlet box adopts three channels for gas inlet, the mode that C2H4, TCS and TMA enter a reaction chamber can be flexibly controlled, and the thickness of large-size SiC epitaxy and the uniformity of doping concentration can be more accurately regulated and controlled; by adjusting the combination of the air inlet channel and the flow, the P-type doping concentration difference between the edge and the center of the SiC epitaxial wafer can be greatly reduced during P-type high-speed epitaxial growth, and low doping concentration non-uniformity is achieved; starting from two aspects of SiC epitaxial equipment hardware and a process method, a simple and effective hardware design scheme and an epitaxial process method are provided to solve the problem of poor doping concentration uniformity of a P-type epitaxial wafer during high-speed epitaxial growth. Compared with single modification of epitaxial equipment or single adjustment of epitaxial process parameters, the method is more time-saving and labor-saving, and the effect is better.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing technology, and in particular to an air intake structure, a P-type silicon carbide epitaxial growth device and a method. Background Art

[0002] The third-generation semiconductor material silicon carbide (SiC) has the advantages of large bandgap, high breakdown field strength, fast electron saturation drift velocity, and high thermal conductivity. It is an ideal material for making high-temperature, high-frequency, high-voltage, and high-power devices. SiC power devices have been widely used in 5G communications, new energy vehicles, smart grids, rail transportation, and other fields.

[0003] All SiC power devices must first grow multiple layers of SiC epitaxial layers doped with N-type or P-type impurities on a SiC substrate, then make SiC chips, and finally package them into SiC power devices. At present, N-type SiC high-speed epitaxial technology and equipment are relatively mature in terms of epitaxial wafer thickness, doping, and defect control. With the increasing application of bipolar devices (such as IGBT) in the field of new energy, SiC bipolar devices are gradually becoming popular. P-type SiC high-speed epitaxy is a key step in the production of SiC bipolar devices, but there is still a lot of room for improvement in the level of related epitaxial technology and equipment. We found in production practice that when using existing horizontal SiC high-temperature epitaxial equipment for high-speed epitaxial growth of P-type SiC, the P-type doping concentration of the epitaxial wafer is extremely uneven. The main manifestation is that along the radial direction of the SiC epitaxial wafer, the P-type doping concentration at the center is very low, and the P-type doping concentration at the edge is very high. The P-type doping non-uniformity of a single SiC epitaxial wafer is greater than 30%, which makes it unable to meet the requirements of large-scale mass production.

[0004] The reason is that aluminum (Al), as a P-type dopant of SiC, has very active chemical properties, which is very different from nitrogen (N), the N-type dopant of SiC. When hydrogen carries trimethylaluminum (providing Al source) through the gas box of the epitaxial furnace and enters the reaction chamber, trimethylaluminum (TMA) quickly decomposes into Al atoms at high temperature (1600℃~1700℃). Therefore, at the edge of the substrate, many Al atoms can quickly combine with C atoms decomposed by ethylene (C2H4) to form Al-C covalent bonds and incorporate into the SiC epitaxial lattice. The number of remaining Al atoms that can move to the center of the substrate is significantly reduced. Naturally, there will be much fewer Al-C bonds incorporated into the SiC epitaxial lattice at the center of the substrate. Since the SiC substrate in the reaction chamber rotates at a speed of 60 revolutions per minute (rpm) during SiC epitaxial growth, this causes the Al doping concentration of the entire SiC epitaxial wafer to be high at the edge and low in the center.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide an air intake structure, a P-type silicon carbide epitaxial growth device and a method to solve the problem that the Al doping concentration of SiC epitaxial wafers in the prior art is high at the edges and low in the center.

[0007] An air intake structure includes an air intake box, wherein the air intake box is provided with a first airflow channel for conveying along the x direction, and second airflow channels are provided on both sides of the first airflow channel along the y direction, the conveying direction of the second airflow channel is consistent with that of the first airflow channel and the two channels are not connected to each other, and the projection areas of the first airflow channel and the second airflow channel along the x direction are S1 and S2 respectively, satisfying the following condition: S1>S2>0.

[0008] Specifically, a third airflow channel for transporting air along the x-direction is provided between the first airflow channel and the second airflow channel, and the third airflow channel is not connected to the first airflow channel and the second airflow channel.

[0009] Specifically, the projection area of ​​the third airflow channel along the x-direction is S3, which satisfies the following condition: S1>S3>S2.

[0010] Specifically, the following conditions are met: S1:S3:S2=10~20:2~6:1.

[0011] A P-type silicon carbide epitaxial growth device, comprising the air intake structure, further comprising: A device body, wherein the device body is provided with a reaction chamber, and the first air flow channel and the second air flow channel are respectively connected to the air inlet end of the reaction chamber; A graphite tray, disposed in the reaction chamber and rotatable around a z-axis, the graphite tray being used to place a SiC substrate; A center line of the first airflow channel along the conveying direction intersects with a rotation center line of the graphite tray.

[0012] Specifically, the epitaxial growth device further includes a heating module disposed on the device body, and the heating module is used to control the temperature of the reaction chamber.

[0013] Specifically, the air inlet box is made of quartz material, and the device body (20) is made of graphite material; The device body is a cylindrical structure, and the heating module includes an induction coil wound around the device body.

[0014] A P-type silicon carbide epitaxial growth method, using the epitaxial growth device, comprises the following steps: P-type SiC high-speed epitaxial growth: A1 reaction chamber 21 is first evacuated to a low vacuum, the vacuum degree of which should reach 1~4 mbar, and then evacuated to a high vacuum, the vacuum degree of which should reach 1E-4~9E-4 mbar, to ensure that the reaction chamber is leak-proof.

[0015] 100-300 slm of hydrogen (H2) is introduced into the A2 reaction chamber 21, and the opening of the butterfly valve is adjusted to control the pressure of the reaction chamber 21 to rise to 960 mbar (atmospheric pressure). At the same time, the heating power is turned on to raise the temperature of the reaction chamber 21 to 850-950°C, and then the SiC substrate is introduced into the reaction chamber 21 and placed on the rotating graphite tray 30.

[0016] A3 adjusts the opening of the butterfly valve of the reaction chamber 21, controls the pressure of the reaction chamber 21 to drop to 50-200 mbar, increases the temperature of the reaction chamber 21 to 1550-1680°C, introduces H2 at a flow rate of 100-300 slm, and then maintains it for 3-10 minutes to perform in-situ etching on the surface of the SiC substrate.

[0017] A4 introduces ethylene (C2H4) with a flow rate of 20-100sccm as a carbon (C) source, trichlorosilane (TCS) with a flow rate of 50-200sccm as a silicon (Si) source, and trimethylaluminum (TMA) with a flow rate of 100-300sccm as an aluminum (Al) source to grow a buffer layer at a growth rate of 8-30um / h and a growth time of 10-20min. Further, by setting a process program, the equipment can automatically control C2H4 and TCS carried by the carrier gas H2 to pass through the first airflow channel 11, the second airflow channel 12 and the third airflow channel 13 of the air inlet box 10 at the same time, but TMA carried by the carrier gas H2 does not pass through the third airflow channel 13, but only passes through the first airflow channel 11 and the second airflow channel 12, wherein the flow ratio of TMA through the first airflow channel 11 and the second airflow channel 12 is about 19:1. In addition, the C2H4 and TCS source gas combination is the key to high-speed SiC epitaxy. Even if the growth rate reaches 100um / h, no silicon droplets will appear on the surface of the epitaxial wafer.

[0018] A5 introduces C2H4 with a flow rate of 50-200sccm as a C source, TCS with a flow rate of 100-400sccm as a Si source, and TMA with a flow rate of 5-60sccm as an Al source to grow an epitaxial layer at a growth rate of 30-70um / h and a growth time of 10-20min. As in the previous step of growing the buffer layer, C2H4 and TCS carried by the carrier gas H2 simultaneously pass through the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 of the air inlet box 10, but TMA carried by the carrier gas H2 does not pass through the third airflow channel 13, but only passes through the first airflow channel 11 and the second airflow channel 12, wherein the flow ratio of TMA through the first airflow channel 11 and the second airflow channel 12 is about 9:1.

[0019] TMA adopts the flow ratio combination of the first gas flow channel 11 and the second gas flow channel 12 as described above, which can ensure that the P-type doping concentration non-uniformity of the SiC epitaxial wafer is reduced to within 2.5% during high-speed epitaxial growth.

[0020] After the growth of A6 is completed, the heating power supply is turned off, the opening of the butterfly valve is adjusted, the pressure of the reaction chamber 21 is increased to 960 mbar, and the temperature of the reaction chamber is waited to drop below 100°C.

[0021] Epitaxial wafer testing: B1 uses the robot arm of the epitaxial furnace to take the grown SiC epitaxial wafer out of the reaction chamber 21.

[0022] B2 Place the SiC epitaxial wafer into a Semilab MCV-530L mercury probe CV tester for P-type doping concentration testing.

[0023] Beneficial effects of the present invention: The air inlet box of the present invention adopts three channels for air inlet, which can not only flexibly control the way C2H4, TCS and TMA enter the reaction chamber, but also more accurately regulate the thickness and uniformity of doping concentration of large-size SiC epitaxy; The present application adopts an epitaxial growth method combining "TMA only passes through the first gas flow channel and the second gas flow channel" and "TMA adopts different flow ratios of the first gas flow channel and the second gas flow channel in the buffer layer and the epitaxial layer", which can greatly reduce the P-type doping concentration difference between the edge and the center of the SiC epitaxial wafer during P-type high-speed epitaxial growth, and achieve lower doping concentration non-uniformity; This application starts from both the hardware and process methods of SiC epitaxy, and proposes a simple and effective hardware design solution and epitaxy process method to solve the problem of poor uniformity of doping concentration of P-type epitaxial wafers during high-speed epitaxial growth. This is more time-saving and labor-saving than simply modifying epitaxial equipment or simply adjusting epitaxial process parameters, and has better results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a three-dimensional diagram of the air intake structure of Example 1; Figure 2 It is a right side view of the air intake structure of Example 1; Figure 3 Schematic diagram of the structure of the P-type silicon carbide epitaxial growth device of Example 1; Figure 4 It is a right side view of the P-type silicon carbide epitaxial growth device of Example 1; Figure 5 for Figure 4 Cross-section of the middle AA surface; Figure 6 for Figure 4 Sectional view of the middle BB surface; Figure 7 It is a structural schematic diagram of the air intake structure and the air intake pipeline of Example 1; Figure 8 The radial distribution of the P-type doping concentration in Example 1, the horizontal axis in the figure is the distance from one end to the other end of the SiC epitaxial wafer along the radial direction, the unit is mm, and the vertical axis is the P-type doping concentration, the unit is cm -3 ; Fig. 9 The radial distribution of P-type doping concentration in comparative example 1, the horizontal axis in the figure is the distance from one end to the other end of the SiC epitaxial wafer along the radial direction, the unit is mm, and the vertical axis is the P-type doping concentration, the unit is cm -3 ; Fig.10 The radial distribution of P-type doping concentration in comparative example 2, in which the horizontal axis is the distance from one end to the other end of the SiC epitaxial wafer along the radial direction, in mm, and the vertical axis is the P-type doping concentration, in cm -3 .

[0025] The reference numerals are: air inlet box 10 , first air flow channel 11 , second air flow channel 12 , third air flow channel 13 , device body 20 , reaction chamber 21 , graphite tray 30 , induction coil 40 , air inlet duct 50 . DETAILED DESCRIPTION

[0026] The present invention provides an air intake structure, a P-type silicon carbide epitaxial growth device and a method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0028] like Figures 1 to 8 As shown, the present embodiment discloses an air intake structure, including an air intake box 10, the air intake box 10 is provided with a first air flow channel 11 for conveying along the x direction, the first air flow channel 11 is provided with a second air flow channel 12 on both sides along the y direction, the second air flow channel 12 is consistent with the conveying direction of the first air flow channel 11 and is not connected to each other, the projection areas of the first air flow channel 11 and the second air flow channel 12 along the x direction are S1 and S2 respectively, satisfying the following conditions: S1>S2>0.

[0029] Furthermore, in this embodiment, the heights of the first airflow channel 11 and the second airflow channel 12 along the z-direction are the same. Therefore, by controlling the lengths of the first airflow channel 11 and the second airflow channel 12 along the y-direction, the projection areas of the first airflow channel 11 and the second airflow channel 12 along the x-direction can be adjusted.

[0030] Furthermore, a third airflow channel 13 for transporting along the x-direction is provided between the first airflow channel 11 and the second airflow channel 12 , and the third airflow channel 13 is not connected to the first airflow channel 11 and the second airflow channel 12 .

[0031] The projection area of ​​the third air flow channel 13 along the x-direction is S3, satisfying the following condition: S1>S3>S2. Similarly, the third air flow channel 13 of this embodiment has the same height as the first air flow channel 11 or the second air flow channel 12 along the z-direction. Therefore, by controlling the length of the third air flow channel 13 along the y-direction, the projection area of ​​the third air flow channel 13 along the x-direction can be adjusted.

[0032] Furthermore, the following condition is met: S1:S3:S2=10~20:2~6:1, and the ratio of the projection areas of the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 along the x-direction can be adjusted according to the actual processing scene.

[0033] Furthermore, the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 are all connected to an air intake pipe 50, and each air intake pipe 50 has a flow meter to control the gas flow. In this way, what gas is passed through each pipe and how much flow is passed can be controlled at will.

[0034] It should be noted that the air inlet box 10 can be installed at the air inlet position of the horizontal SiC epitaxial equipment, and the width of the air inlet box 10 can be slightly larger than the diameter of the SiC substrate to ensure that the gas flowing through the air inlet box 10 and entering the reaction chamber 21 can cover the entire SiC substrate.

[0035] This embodiment also discloses a P-type silicon carbide epitaxial growth device, including an air intake structure, and further comprising: The device body 20 is provided with a reaction chamber 21, the reaction chamber 21 is connected with the air inlet box 10 through a graphite transition piece, and the first air flow channel 11 and the second air flow channel 12 are respectively connected with the air inlet end of the reaction chamber 21; A graphite tray 30 is disposed in the reaction chamber 21 and can rotate around the z-axis. Specifically, hydrogen or argon gas can be used to blow the graphite tray 30 around the z-axis. The graphite tray 30 is used to place the SiC substrate. The center line of the first air flow channel 11 along the conveying direction intersects with the rotation center line of the graphite tray 30 .

[0036] The epitaxial growth device further includes a heating module disposed on the device body 20 , and the heating module is used to control the temperature of the reaction chamber 21 .

[0037] The air inlet box 10 is made of quartz material, and the device body 20 is made of graphite material; The device body 20 is a cylindrical structure. The heating module includes an induction coil 40 wound around the device body 20. The induction coil 40 is used for heating. Conductive steel pipes cannot be used inside the vacuum chamber of the device body 20, and a non-conductive quartz air inlet box 10 is used at the air inlet position at the right end of the vacuum chamber to transport the reaction gas.

[0038] This embodiment also discloses a P-type silicon carbide epitaxial growth method, using an epitaxial growth device, comprising the following steps: P-type SiC high-speed epitaxial growth: A1 reaction chamber 21 is first evacuated to a low vacuum, the vacuum degree of which must reach 2 mbar, and then evacuated to a high vacuum, the vacuum degree of which must reach 5E-4 mbar, to ensure that the reaction chamber is leak-proof.

[0039] 150 slm of H2 was introduced into the A2 reaction chamber 21, and the opening of the butterfly valve was adjusted to control the pressure of the reaction chamber 21 to rise to 960 mbar. At the same time, the heating power was turned on to raise the temperature of the reaction chamber 21 to 900°C, and then the SiC substrate was introduced into the reaction chamber 21 and placed on the rotating graphite tray 30.

[0040] A3 adjusts the opening of the butterfly valve of the reaction chamber 21, controls the pressure of the reaction chamber 21 to drop to 100 mbar, raises the temperature of the reaction chamber 21 to 1650°C, introduces H2 at a flow rate of 150 slm, and then maintains it for 5 minutes to perform in-situ etching on the surface of the SiC substrate.

[0041] A4 is fed with C2H4 at a flow rate of 30sccm as a carbon source, TCS at a flow rate of 55sccm as a silicon source, and TMA at a flow rate of 200sccm as an aluminum source to grow a buffer layer at a growth rate of 10um / h and a growth time of 17min. Further, by setting a process program, the equipment can automatically control the C2H4 and TCS carried by the carrier gas H2 to pass through the first gas flow channel 11, the second gas flow channel 12 and the third gas flow channel 13 of the gas inlet box 10 at the same time, but the TMA carried by the carrier gas H2 does not pass through the third gas flow channel 13, but only passes through the first gas flow channel 11 and the second gas flow channel 12, wherein the flow rates of TMA through the first gas flow channel 11 and the second gas flow channel 12 are 190sccm and 10sccm respectively. In addition, the combination of C2H4 and TCS source gases is the key to high-speed epitaxy of SiC. Even if the growth rate reaches 100um / h, silicon droplets will not appear on the surface of the epitaxial wafer.

[0042] A5 passes C2H4 with a flow rate of 120sccm as a carbon source, TCS with a flow rate of 290sccm as a silicon source, and TMA with a flow rate of 50sccm as an aluminum source to grow an epitaxial layer with a C / Si ratio of 0.83, a growth rate of 50um / h, and a growth time of 13min. As in the previous step of growing the buffer layer, C2H4 and TCS carried by the carrier gas H2 simultaneously pass through the first gas flow channel 11, the second gas flow channel 12, and the third gas flow channel 13 of the gas inlet box 10, but TMA carried by the carrier gas H2 does not pass through the third gas flow channel 13, but only passes through the first gas flow channel 11 and the second gas flow channel 12, wherein the flow rates of TMA through the first gas flow channel 11 and the second gas flow channel 12 are 45sccm and 5sccm respectively.

[0043] After the growth of A6 is completed, the heating power supply is turned off, the opening of the butterfly valve is adjusted, the pressure of the reaction chamber 21 is increased to 960 mbar, and the temperature of the reaction chamber is waited to drop below 100°C.

[0044] Epitaxial wafer testing: B1 uses the robot arm of the epitaxial furnace to take the grown SiC epitaxial wafer out of the reaction chamber 21.

[0045] B2 Place the SiC epitaxial wafer into a Semilab MCV-530L mercury probe CV tester to test the P-type doping concentration. For the test results, please refer to Figure 8 .

[0046] Depend on Figure 8 It can be seen from the radial distribution diagram of the P-type doping concentration that this embodiment can reduce the non-uniformity of the P-type doping concentration of the SiC epitaxial wafer to within 2.5%, thereby ensuring the uniformity of the P-type doping concentration of the epitaxial wafer.

[0047] The above-mentioned air intake structure, P-type silicon carbide epitaxial growth device and epitaxial growth method have the following advantages: First, the epitaxial furnace's air inlet box 10 uses three channels for air intake, which can not only flexibly control the way C2H4, TCS, and TMA enter the reaction chamber 21, but also more accurately regulate the thickness and doping concentration uniformity of large-size (6, 8 inches, and even 12 inches) SiC epitaxy.

[0048] Secondly, the present application adopts an epitaxial growth method that combines "TMA only through the first airflow channel 11 and the second airflow channel 12" and "TMA uses different flow ratios of the first airflow channel 11 and the second airflow channel 12 in the buffer layer and the epitaxial layer". It can greatly reduce the P-type doping concentration difference between the edge and the center of the SiC epitaxial wafer during P-type high-speed epitaxial growth, thereby achieving lower doping concentration non-uniformity.

[0049] In summary, this application starts from both the hardware and process methods of SiC epitaxy, and proposes a simple and effective hardware design solution and epitaxy process method to solve the problem of poor uniformity of doping concentration of P-type epitaxial wafers during high-speed epitaxial growth. This is more time-saving and labor-saving than simply modifying epitaxial equipment or simply adjusting epitaxial process parameters, and has better results.

[0050] Comparative Example 1 Please refer to Figures 1 to 7 .

[0051] P-type SiC high-speed epitaxial growth: The C1 reaction chamber 21 is first evacuated to a low vacuum, the vacuum degree of which must reach 2 mbar, and then evacuated to a high vacuum, the vacuum degree of which must reach 5E-4 mbar, to ensure that the reaction chamber is leak-proof.

[0052] 150 slm of H2 was introduced into the C2 reaction chamber, and the opening of the butterfly valve of the reaction chamber 21 was adjusted to control the pressure of the reaction chamber 21 to 960 mbar. At the same time, the heating power supply was turned on to raise the temperature of the reaction chamber 21 to 900°C, and then the SiC substrate was introduced into the reaction chamber 21 and placed on the rotating graphite tray 30.

[0053] C3 adjusts the opening of the butterfly valve to control the pressure of the reaction chamber 21 to drop to 100 mbar. The temperature of the reaction chamber is raised to 1650°C, and H2 with a flow rate of 150 slm is introduced, and then maintained for 5 minutes to perform in-situ etching on the surface of the SiC substrate.

[0054] C4 is fed with a flow rate of 30sccm of C2H4, a flow rate of 55sccm of TCS, and a flow rate of 200sccm of TMA to grow a buffer layer, C / Si is 1.1, a growth rate of 10um / h, and a growth time of 17min. Different from Example 1, C2H4, TCS, and TMA carried by carrier gas H2 simultaneously pass through the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 of the air inlet box 10, wherein the flow rates of TMA passing through the first airflow channel 11, the third airflow channel 13, and the second airflow channel 12 are 120sccm, 64sccm, and 16sccm, respectively. This is equivalent to removing the four quartz partitions inside the air inlet box 10 and turning it into a large airflow channel without spacing.

[0055] C5 is fed with C2H4 at a flow rate of 120 sccm, TCS at a flow rate of 290 sccm, and TMA at a flow rate of 50 sccm to grow an epitaxial layer, with a C / Si ratio of 0.83, a growth rate of 50 um / h, and a growth time of 13 min. C2H4, TCS, and TMA carried by carrier gas H2 simultaneously pass through the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 of the air inlet box 10, wherein the flow rates of TMA through the first airflow channel 11, the third airflow channel 13, and the second airflow channel 12 are 30 sccm, 16 sccm, and 4 sccm, respectively.

[0056] After the growth of C6 is completed, the heating power supply is turned off, the opening of the butterfly valve is adjusted, the pressure of the reaction chamber 21 is increased to 960 mbar, and the temperature of the reaction chamber is waited to drop below 100°C.

[0057] Epitaxial wafer testing: D1 uses the robot of the epitaxial furnace to take the grown SiC epitaxial wafer out of the reaction chamber.

[0058] D2 put the SiC epitaxial wafer into the Semilab MCV-530L mercury probe CV tester to test the P-type doping concentration. For the test results, please refer to Fig. 9 .

[0059] Comparative Example 2 Please refer to Figures 1 to 7 .

[0060] P-type SiC high-speed epitaxial growth: The E1 reaction chamber 21 is first evacuated to a low vacuum, the vacuum degree of which must reach 2 mbar, and then evacuated to a high vacuum, the vacuum degree of which must reach 5E-4 mbar, to ensure that the reaction chamber is leak-proof.

[0061] 150 slm of H2 was introduced into the E2 reaction chamber 21, and the opening of the butterfly valve was adjusted to control the pressure of the reaction chamber 21 to 960 mbar. At the same time, the heating power was turned on to raise the temperature of the reaction chamber 21 to 900°C, and then the SiC substrate was introduced into the reaction chamber 21 and placed on the rotating graphite tray 30.

[0062] E3 adjusts the opening of the butterfly valve to control the pressure of the reaction chamber 21 to 100 mbar. The temperature of the reaction chamber 21 is raised to 1650° C., and H2 with a flow rate of 150 slm is introduced, and then maintained for 5 minutes to perform in-situ etching on the surface of the SiC substrate.

[0063] E4 is fed with C2H4 with a flow rate of 30sccm, TCS with a flow rate of 55sccm, TMA with a flow rate of 200sccm, and a growth buffer layer, C / Si is 1.1, a growth rate of 10um / h, and a growth time of 17min. Different from Example 1, C2H4 and TCS carried by carrier gas H2 pass through the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 of the air inlet box 10 at the same time, but TMA carried by H2 only passes through the first airflow channel 11, that is, the flow rate of TMA passing through the first airflow channel 11 is 200sccm. This is equivalent to removing 2 quartz partitions between the second airflow channel 12 and the third airflow channel 13 inside the air inlet box 10, and the second airflow channel 12 and the third airflow channel 13 are combined into an airflow channel without a gap.

[0064] E5 is fed with C2H4 at a flow rate of 120 sccm, TCS at a flow rate of 290 sccm, and TMA at a flow rate of 50 sccm to grow an epitaxial layer, with a C / Si ratio of 0.83, a growth rate of 50 um / h, and a growth time of 13 min. C2H4 and TCS carried by the carrier gas H2 simultaneously pass through the first gas flow channel 11, the second gas flow channel 12, and the third gas flow channel 13 of the gas inlet box 10, but TMA carried by H2 only passes through the first gas flow channel 11, that is, the flow rate of TMA passing through the first gas flow channel 11 is 50 sccm.

[0065] After the growth of E6 is completed, the heating power supply is turned off, the opening of the butterfly valve is adjusted, the pressure of the reaction chamber 21 is increased to 960 mbar, and the temperature of the reaction chamber is waited to drop below 100°C.

[0066] Epitaxial wafer testing: F1 uses the robot of the epitaxial furnace to take out the grown SiC epitaxial wafer from the reaction chamber 21.

[0067] F2 puts the SiC epitaxial wafer into the Semilab MCV-530L mercury probe CV tester to test the P-type doping concentration. Please refer to the test results. Fig.10 .

[0068] The difference between Example 1 and Comparative Example 1 and Comparative Example 2 is that the TMA of Example 1 only passes through the first airflow channel 11 and the second airflow channel 12 of the air inlet box 10, and the TMA flow ratios of the first airflow channel 11 and the second airflow channel 12 are 19:1 (buffer layer) and 9:1 (epitaxial layer), respectively; the TMA of Comparative Example 1 passes through the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13 of the air inlet box 10 (equivalent to no gap between the first airflow channel 11, the second airflow channel 12, and the third airflow channel 13); the TMA of Comparative Example 2 only passes through the first airflow channel 11 of the air inlet box 10 (equivalent to no gap between the second airflow channel 12 and the third airflow channel 13), and the other process parameters of epitaxial growth are the same.

[0069] The SiC epitaxial wafers (3 in total) produced in Example 1, Comparative Example 1 and Comparative Example 2 were tested for doping concentration on the same testing machine, and then the average value and uniformity of the P-type doping concentration of the 3 epitaxial wafers were compared and analyzed.

[0070] Fig. 9 The radial distribution of P-type doping concentration in comparative example 1 has an average doping concentration of 1.08E+16cm -3 , the doping concentration non-uniformity is 36.19%; Fig.10 The radial distribution of P-type doping concentration in comparative example 2 has an average doping concentration of 1.27E+16cm -3 , the doping concentration non-uniformity is 5.13%; Figure 8 The radial distribution of the P-type doping concentration in Example 1 has an average doping concentration of 1.31E+16cm -3 , the doping concentration non-uniformity is 2.20%. Obviously, by using the air intake structure, P-type silicon carbide epitaxial growth device and method of Example 1, very good P-type doping concentration uniformity can be obtained during high-speed epitaxial growth, and the average value of the doping concentration is also relatively close. Therefore, the epitaxial growth device and method proposed by the present invention are simple and effective.

[0071] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. An air intake structure, characterized in that: The invention comprises an air intake box (10), wherein the air intake box (10) is provided with a first air flow channel (11) for conveying along the x direction, and second air flow channels (12) are provided on both sides of the first air flow channel (11) along the y direction, and the conveying directions of the second air flow channel (12) and the first air flow channel (11) are consistent and are not connected to each other, and the projection areas of the first air flow channel (11) and the second air flow channel (12) along the x direction are S1 and S2 respectively, and the following condition is satisfied: S1>S2>0.

2. An air intake structure according to claim 1, characterized in that: A third airflow channel (13) for transporting air along the x-direction is provided between the first airflow channel (11) and the second airflow channel (12); the third airflow channel (13) is not connected to the first airflow channel (11) or the second airflow channel (12).

3. An air intake structure according to claim 2, characterized in that: The projection area of ​​the third airflow channel (13) along the x-direction is S3, which satisfies the following condition: S1>S3>S2.

4. An air intake structure according to claim 3, characterized in that: Meet the following conditions: S1:S3:S2=10~20:2~6:

1.

5. A P-type silicon carbide epitaxial growth device, comprising the air intake structure according to any one of claims 1 to 4, characterized in that: Also includes: A device body (20), wherein the device body (20) is provided with a reaction chamber (21), and the first air flow channel (11) and the second air flow channel (12) are respectively connected to an air inlet end of the reaction chamber (21); A graphite tray (30) is disposed in the reaction chamber (21) and is rotatable about a z-axis, wherein the graphite tray (30) is used to place a SiC substrate; A center line of the first airflow channel (11) along the conveying direction intersects with a rotation center line of the graphite tray (30).

6. A P-type silicon carbide epitaxial growth device according to claim 5, characterized in that: The epitaxial growth device further comprises a heating module arranged on the device body (20), and the heating module is used to control the temperature of the reaction chamber (21).

7. A P-type silicon carbide epitaxial growth device according to claim 5, characterized in that: The air inlet box (10) is made of quartz material, and the device body (20) is made of graphite material; The device body (20) is a cylindrical structure, and the heating module comprises an induction coil (40) wound around the device body (20).

8. A method for epitaxial growth of P-type silicon carbide, using the epitaxial growth apparatus as claimed in claim 5, characterized in that: The following steps are involved: D1 placing the SiC substrate on a rotating graphite tray (30); D2 introduces a carbon source, a silicon source and an aluminum source into the reaction chamber (21) to grow a buffer layer on the SiC substrate, wherein the aluminum source is introduced simultaneously through the first gas flow channel (11) and the second gas flow channel (12), and the flow ratio of the aluminum source through the first gas flow channel (11) and the second gas flow channel (12) is 15-25:1; D3 introduces a carbon source, a silicon source and an aluminum source into the reaction chamber (21) to grow an epitaxial layer on the buffer layer, wherein the aluminum source is introduced simultaneously through the first gas flow channel (11) and the second gas flow channel (12), and the flow ratio of the aluminum source through the first gas flow channel (11) and the second gas flow channel (12) is 6-12:

1.

9. A P-type silicon carbide epitaxial growth method according to claim 8, characterized in that: Before step D1, the method further includes the following steps: D11 evacuates the reaction chamber (21) to a vacuum level of 1E-4 to 9E-4 mbar; D12 introduces a carrier gas into the reaction chamber (21), raises the pressure of the reaction chamber (21) to a level equivalent to the standard atmospheric pressure, and raises the temperature of the reaction chamber (21) to 850-950° C.; Between step D1 and step D2, the following steps are also included: D21: reducing the pressure of the reaction chamber (21) to 50-200 mbar, increasing the temperature of the reaction chamber (21) to 1550-1680° C., introducing a carrier gas, and maintaining the temperature for 3-10 minutes to perform in-situ etching on the surface of the SiC substrate; After step D3, the method further includes the following steps: D4 raises the pressure of the reaction chamber (21) to the equivalent of standard atmospheric pressure and reduces the temperature of the reaction chamber (21) to below 100°C.

10. A P-type silicon carbide epitaxial growth method according to claim 8, characterized in that: The carrier gas is hydrogen, the carbon source is ethylene, the silicon source is trichlorosilane, and the aluminum source is trimethylaluminum.

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