A silicon carbide epitaxial device

Abstract

This application discloses a silicon carbide epitaxial growth apparatus, comprising a reaction chamber with a shell containing a first graphite cylinder and a second graphite cylinder coaxially arranged therein. The first and second graphite cylinders are spaced apart, and the second graphite cylinder is made of porous graphite material with a pore size between 100-1000 nm. A spray device is disposed on one side of the shell, and the spray device includes an air inlet ring disposed at one end of the first and second graphite cylinders, which is connected to a purge gas supply unit. A drive component is connected through the bottom plate of the shell to a rotating support unit located inside the shell, and a wafer support tray is disposed on the side of the rotating support unit away from the drive component. In this way, purge gas is supplied through the air inlet ring, and the purge gas permeates and passes through the second graphite cylinder while flowing towards the bottom plate, forming a protective film on the surface of its inner wall, avoiding the deposition of side reaction particles, extending the service life of the second graphite cylinder, and improving the yield of epitaxial growth.

Description

Technical Field

[0001] This application relates to the field of epitaxial technology, specifically to a silicon carbide epitaxial device. Background Technology

[0002] CVD equipment is a high-tech device integrating vacuum, high temperature, and high-speed rotation technologies. During epitaxial growth, process gases are introduced into the reaction chamber and flow through the heated substrate, where a chemical reaction occurs on the substrate surface to generate single-crystal thin films of GaN, AlN, SiC, or other materials. Taking silicon carbide as an example, the temperature inside the reaction chamber during epitaxial growth is between 1600℃ and 1700℃. In addition to the formation of single-crystal thin films on the substrate surface under high temperature conditions, side reactions occur, forming thin films on the sidewalls of the reaction chamber and the surface of the wafer tray. As the number of epitaxial reactions increases, the cumulative thickness of the thin films formed on the sidewalls of the reaction chamber and the surface of the wafer tray increases, making them prone to detachment. When these films fall onto the substrate, they cause epitaxial defects. Therefore, it is necessary to replace the graphite cylinder and wafer tray inside the reaction chamber, increasing operating costs.

[0003] Therefore, it is necessary to improve existing silicon carbide epitaxial equipment. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, the purpose of this application is to provide a silicon carbide epitaxial device that optimizes the structure of the reaction chamber, extends the service life of the graphite cylinder and wafer support tray, and improves the quality of epitaxial growth.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] A silicon carbide epitaxial device, comprising:

[0007] The reaction chamber includes:

[0008] The housing includes a first graphite cylinder and a second graphite cylinder arranged coaxially from the outside to the inside. The first graphite cylinder and the second graphite cylinder are spaced apart. The second graphite cylinder is made of a porous medium with a pore size between 100-1000 nm.

[0009] A spraying device is disposed on one side of the housing. The spraying device includes a spray head and an air inlet ring sleeved on the spray head. The air inlet ring is disposed on one side of the first graphite cylinder and the second graphite cylinder, and is used to introduce purging gas into the gap between the first graphite cylinder and the second graphite cylinder.

[0010] A driving component is disposed on the side of the housing opposite to the spraying device. The driving component is connected to a rotating support located inside the housing through the bottom plate of the housing. The side of the rotating support away from the driving component is used to place a wafer tray. During epitaxial growth, a purge gas (such as argon) is supplied through the air inlet ring. While flowing towards the bottom plate within the gap between the first and second graphite cylinders, the purge gas partially permeates and passes through the second graphite cylinder. The purge gas passing through the second graphite cylinder flows along the surface of its inner wall towards the bottom plate, forming a protective film on the surface of the inner wall of the second graphite cylinder. This prevents particles generated by side reactions (also known as pre-reactions) of the process gas introduced by the spray head from depositing on the surface of the inner wall of the second graphite cylinder, thereby extending the service life of the second graphite cylinder and improving the yield of epitaxial growth.

[0011] Preferably, the air intake ring includes a substrate, one side of which is disposed at one end of the first graphite cylinder and the second graphite cylinder, and this side has a first protrusion and a second protrusion extending along the axial direction of the substrate and toward the rotation support portion. The combination of the substrate and the first and second protrusions forms an air intake groove. The substrate is provided with an air intake port, which is connected to a purge gas supply portion through an air intake pipe, and the air intake pipe is provided with a first pressure sensor.

[0012] The substrate has a third protrusion extending axially along the side of the substrate away from the first protrusion, and the third protrusion is annular. The space enclosed by the third protrusion accommodates the spray head.

[0013] Preferably, the housing includes a first housing and a second housing arranged coaxially, with the first housing located near the spray device.

[0014] Preferably, the first housing is coaxially arranged from the outside to the inside with a heat insulation component, a first heater, a first graphite cylinder and a second graphite cylinder, and the surface of the first graphite cylinder is coated with a silicon carbide coating.

[0015] Preferably, the second housing is coaxially arranged from the outside to the inside with an air extraction ring and a rotating support portion. The air extraction ring includes a base, which is annular and has ventilation holes. One side of the base has a first sidewall and a second sidewall disposed opposite to each other. The first sidewall is located on the side of the second sidewall away from the rotating support portion. The combination of the first sidewall, the second sidewall, and the base forms a groove.

[0016] A second pressure sensor is also provided inside the second housing to measure the air pressure inside the second graphite cylinder.

[0017] Preferably, the first sidewall has a base and a baffle, the plane of the base is parallel to the plane of the second sidewall, and the baffle is configured to be inclined from the base toward the second graphite cylinder side.

[0018] Preferably, at least one shielding part is provided in the gap between the first graphite cylinder and the second graphite cylinder, the shielding part being used to slow down the flow rate of the purge gas in the gap between the first graphite cylinder and the second graphite cylinder. In this way, the gas pressure in the gap space is the same or approximately the same.

[0019] Preferably, the shielding portion is arranged circumferentially along the first graphite cylinder or the second graphite cylinder.

[0020] Preferably, the rotating support includes a support body, which is a hollow cylindrical shape and has a plurality of first vent holes extending along its axial direction and penetrating through it. The plurality of first vent holes are evenly distributed along the circumferential direction of the support body. A support base plate is installed at the bottom of the support body, which has a second vent hole extending radially upward therein. One end of the second vent hole is connected to a third vent hole on the drive component, and the other end is used to connect to the first vent hole. The air inlet of the third vent hole is connected to the purge gas supply unit through a pipeline.

[0021] Preferably, the wafer support tray includes a support frame and a cover plate;

[0022] The cover plate is a hollow ring and is made of porous graphite material with a pore size between 100-1000 nm.

[0023] The support frame has a groove, and the bottom of the groove is provided with a perforation. The number of perforations matches the number of the first ventilation holes. The support frame is placed on the side of the support body away from the support base plate. The cover plate is placed on the support frame and combines with the groove to form a uniform air groove. Beneficial effects

[0024] Compared to existing epitaxial equipment, the epitaxial equipment proposed in this application optimizes the structure of the reaction chamber, which includes a first graphite cylinder and a second graphite cylinder coaxially arranged. The second graphite cylinder is made of porous graphite material, and there is a gap between the first and second graphite cylinders. During epitaxial growth, a purge gas (such as argon) is introduced into the space of this gap through an air inlet ring. While the purge gas flows towards the bottom plate, it partially permeates into and passes through the second graphite cylinder. The purge gas passing through the second graphite cylinder flows towards the bottom plate along the surface of its inner wall, forming a protective film on the inner wall surface of the second graphite cylinder. This prevents particles generated by side reactions of the process gas introduced by the spray head from depositing on the inner wall surface of the second graphite cylinder, thereby extending the service life of the second graphite cylinder. This method can effectively avoid the impact of particle shedding from the inner wall on the process results, improve the yield, and also increase the maintenance cycle of the second graphite cylinder. Attached Figure Description

[0025] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this application.

[0026] Figure 1 This is a three-dimensional structural diagram of the reaction chamber according to an embodiment of this application;

[0027] Figure 2 This is a top view of a reaction chamber according to an embodiment of this application;

[0028] Figure 3 for Figure 2 Schematic diagram of the cross section at point AA;

[0029] Figure 4 for Figure 3 An isometric schematic diagram;

[0030] Figure 5 This is a three-dimensional structural schematic diagram of the intake ring according to an embodiment of this application;

[0031] Figure 6 This is a three-dimensional structural schematic diagram of the second graphite cylinder according to an embodiment of this application;

[0032] Figure 7 This is a three-dimensional structural schematic diagram of the second graphite cylinder according to another embodiment of this application;

[0033] Figure 8 This is a schematic diagram showing the connection between the second housing and the driving component according to an embodiment of this application;

[0034] Figure 9 for Figure 8 A diagram showing the view from below;

[0035] Figure 10 for Figure 9 Schematic diagram of the cross section at point BB;

[0036] Figure 11 for Figure 7 A schematic diagram with the cover plate hidden in the middle;

[0037] Figure 12 This is a schematic diagram of the support frame according to an embodiment of this application;

[0038] Figure 13 This is a schematic diagram of the structure of a support body according to an embodiment of this application. Detailed Implementation

[0039] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0040] In this application, the terms "upper," "lower," "inner," "middle," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0041] This application discloses a silicon carbide epitaxial device, including a reaction chamber comprising a housing containing a first graphite cylinder and a second graphite cylinder coaxially arranged therein. The first graphite cylinder and the second graphite cylinder are spaced apart, and the second graphite cylinder is made of porous graphite material with a pore size between 100-1000 nm. A spray device is disposed on one side of the housing, and the spray device includes an air inlet ring disposed at one end of the first graphite cylinder and the second graphite cylinder. The air inlet ring is connected to a purge gas supply unit via an air inlet pipe (the air inlet pipe is equipped with a first pressure sensor). A drive component is also disclosed, which passes through the bottom plate of the housing and is connected to a rotating support unit located inside the housing. The side of the rotating support unit away from the drive component is used to place a wafer tray (on which a wafer is placed) for placing a wafer. In this way, purge gas is supplied through the air inlet ring. The purge gas flows in the gap between the first graphite cylinder and the second graphite cylinder and permeates and passes through the second graphite cylinder, forming a protective film on the inner wall surface of the second graphite cylinder. This increases the service life of the second graphite cylinder and improves the yield. During operation, the pressure in the gap between the first and second graphite cylinders of this epitaxial device is greater than the pressure inside the second graphite cylinder. This ensures that the purge gas permeates to the inner wall of the second graphite cylinder, preventing the process gas / reaction gas from contacting the inner surface of the second graphite cylinder. In this application, the wafer is sometimes also referred to as the substrate. The wafer support tray is sometimes also referred to as the tray.

[0042] Next, we will combine the appendix Figures 1-13 The present application describes a silicon carbide epitaxial apparatus (hereinafter referred to as the epitaxial apparatus). This epitaxial apparatus can be used for epitaxial growth of GaN, AlN, and gallium oxide, and preferably, it is used for silicon carbide epitaxial growth.

[0043] The epitaxial apparatus includes a reaction chamber 100, which includes a housing 110 in a cylindrical shape. The epitaxial apparatus also includes a transfer chamber located on one side of the reaction chamber 100, which contains a robotic arm for transferring wafers (or wafer trays for placing wafers).

[0044] A spray device is installed at one end of the housing 110, and a drive component 130 is installed at the opposite end. The drive component 130 is connected to a rotating support 140 inside the housing through the bottom plate 110c of the housing 110. The rotating support 140 is used to place a wafer tray 150, on which a wafer 200 is placed. The rotating support 140 is driven by the drive component 130 to rotate. A vacuum port 110c1 is provided on the bottom plate 110c. The vacuum port is connected to a vacuum device (not shown) through a pipeline to discharge gas (such as that introduced by the spray device).

[0045] The spray device is located above the wafer tray 150. The spray device includes a disc-shaped spray head (not shown) and an air inlet ring 120 located outside the spray head. The spray head is connected to the gas supply unit through a pipeline for introducing process gas during epitaxy.

[0046] The air intake ring 120 includes a base plate 121. One side of the base plate 121 has a first protrusion 123 and a second protrusion 122 extending axially along the base plate 121 and toward the rotation support portion. The combination of the base plate 121, the first protrusion 123, and the second protrusion 122 forms an air intake groove. On the side of the base plate 121 away from the first protrusion 123, a third protrusion 124 extending axially along the base plate has a ring-shaped protrusion 124, which is fitted onto the spray head. Two air inlets 121a are provided on the base plate. These air inlets 121a are connected to a purge gas supply unit via air intake pipes, and purge gas (such as argon) is supplied by the purge gas supply unit. In this embodiment, a first pressure sensor (not shown) is provided on the air intake pipe connected to the air inlets 121a. The two air inlets 121a are symmetrically arranged. The air inlet 121a is located 122 between the first protrusion 123 and the second protrusion. Purge gas (such as argon) is introduced into the inlet slot through the inlet 121a, and the purge gas flows into the gap between the first and second graphite cylinders described below. A spray head is used to introduce process gas during epitaxy; the introduced process gas is located inside the second graphite cylinder.

[0047] The housing includes a first housing 110a and a second housing 110b arranged coaxially (in series), with the first housing 110a located near the spray device.

[0048] The first housing 110a contains, from the outside in, a heat-insulating component 111, a first heater 112, a first graphite cylinder 113, and a second graphite cylinder 114. Preferably, the first heater includes at least two sub-heaters (e.g., three sub-heaters), which are sleeved on the outside of the first graphite cylinder 113 and arranged along the axial direction of the first graphite cylinder 113. The sub-heaters can be graphite heaters. Preferably, the first graphite cylinder 113 and the second graphite cylinder 114 are coaxially arranged.

[0049] Both the first graphite cylinder 113 and the second graphite cylinder 114 are cylindrical, and a gap exists between them. The second graphite cylinder 114 is made of porous graphite material, and the pore size of the porous medium is between 100-1000 nm. In one embodiment, at least one shielding portion is provided in the gap between the first graphite cylinder 113 and the second graphite cylinder 114. This shielding portion is used to slow down the flow rate of the purge gas in the gap between the first graphite cylinder and the second graphite cylinder. During epitaxial growth, the purge gas permeates into the second graphite cylinder and forms a protective film on the inner wall surface of the second graphite cylinder. The shielding portion is arranged circumferentially along the first graphite cylinder or the second graphite cylinder. A second pressure sensor is provided inside the housing (e.g., a second pressure sensor is provided inside the second housing 110b), and this second pressure sensor is used to measure the gas pressure inside the second graphite cylinder. The gap between the first graphite cylinder 113 and the second graphite cylinder 114 is between 2 and 5 mm. This design ensures that the purging gas flows while partially penetrating and passing through the second graphite cylinder. The purging gas passing through the second graphite cylinder flows along the surface of its inner wall (under the action of the vacuum device) towards the bottom plate side, forming a uniform protective film on the inner wall surface of the second graphite cylinder.

[0050] The intake ring 120 is disposed on one side of the first graphite cylinder 113 and the second graphite cylinder 114 (such as overlapping one side of the first graphite cylinder 113 and the second graphite cylinder 114), and both the first graphite cylinder 113 and the second graphite cylinder 114 are embedded in the intake groove, such as the first graphite cylinder 113 contacting the second protrusion 122, and the second graphite cylinder 114 contacting the first protrusion 123.

[0051] Multiple shielding portions are provided within the gap between the first graphite cylinder 113 and the second graphite cylinder 114. The ends of the shielding portions have gaps with the surface of the first or second graphite cylinder, through which the purge gas flows toward the wafer tray 150 / base plate side. The shielding portions are used to slow down the flow rate of the purge gas in the gap between the first and second graphite cylinders. During epitaxial growth, the purge gas permeates into the second graphite cylinder and forms a protective film on the inner surface (i.e., the inner wall surface) of the second graphite cylinder.

[0052] In one embodiment, three blocking portions (such as those arranged at approximately equal intervals) are provided within the gap between the first graphite cylinder and the second graphite cylinder. These three blocking portions are a first blocking portion, a second blocking portion, and a third blocking portion, and are spaced apart along the axis of the second graphite cylinder. Each of the first, second, and third blocking portions includes sub-blocking portions. Taking the first blocking portion as an example, it is composed of multiple sub-blocking portions, with intervals between adjacent sub-blocking portions.

[0053] See Figure 6The second graphite cylinder 114 includes a body 114a, which is a hollow cylinder. A first blocking portion 114a1 and a second blocking portion 114a2 are provided on the outer surface of the body 114a, and the first blocking portion and the second blocking portion are spaced apart. The first blocking portion 114a1 includes multiple sub-blocking portions, with gaps 114a11 between adjacent sub-blocking portions. The second blocking portion also includes multiple sub-blocking portions, with gaps between adjacent sub-blocking portions. The first shielding portion 114a1 and the second shielding portion 114a2 divide the gap 115 between the first graphite cylinder and the second graphite cylinder into a first purge chamber, a second purge chamber, and a third purge chamber. The first purge chamber is closer to the inlet ring side, and the third purge chamber is closer to the rotating support side. This design ensures that the flow rate of the purge gas is slowed down during epitaxial growth. The pressures in the first, second, and third purge chambers are the same or approximately the same. While flowing, the purge gas is partially diffused by the pressure difference (the pressure inside the second graphite cylinder) and permeates through the porous medium of the second graphite cylinder to the surface of the inner wall. This forms a protective effect on the surface of the inner wall (the side of the second graphite cylinder closer to the process gas), preventing the process gas from directly contacting the inner wall of the second graphite cylinder, thereby extending the service life of the first and second graphite cylinders. The inner wall 114a3 on one side of the body 114a has a protrusion 114b extending radially upward therefrom.

[0054] As Figure 6 For variations of the implementation method, see [link to implementation details]. Figure 7 The second graphite cylinder 214 includes a body 214a, which is a hollow cylinder. A first blocking part 214a1, a second blocking part 214a2 and a third blocking part 214a3 are provided on the outer surface of the body 214a, and the first blocking part, the second blocking part and the third blocking part are spaced apart. The first shielding part 214a1, the second shielding part 214a2, and the third shielding part 214a3 divide the gap (gap space) between the first graphite cylinder and the second graphite cylinder into a first purge chamber, a second purge chamber, and a third purge chamber. The first purge chamber is closer to the air inlet ring side, and the third purge chamber is closer to the rotating support side. This design ensures that the flow rate of the purge gas is slowed down during the epitaxial growth process. While the purge gas is flowing, it is partially diffused by the pressure difference and passes through the porous medium of the second graphite cylinder to the surface of the inner wall, so as to form a protective effect on the surface of the inner wall (the side of the second graphite cylinder closer to the process gas), preventing the process gas from directly contacting the inner wall surface of the second graphite cylinder, thereby extending the service life of the first graphite cylinder and the second graphite cylinder.

[0055] The second housing 110b is provided with an air extraction ring 116, a heat insulation plate 117 and a rotating support part 140 arranged sequentially from the outside to the inside.

[0056] The suction ring 116 (also called a suction groove, with its opening facing the spray device) is annular in design, ensuring uniform pressure along the circumference of the second graphite cylinder and allowing the purging gas to diffuse evenly onto the inner wall of the second graphite cylinder. Preferably, the orthogonal projection of the second graphite cylinder onto the suction ring 116 is located within the opening. A second heater (not shown) is disposed within the rotating support.

[0057] The suction ring 116 includes a base, which is annular and has vent holes (preferably, the vent holes are evenly distributed on the base). One side of the base has a first sidewall and a second sidewall disposed opposite to each other, and the combination of the first sidewall, the second sidewall, and the base forms a groove. The suction ring 116 is sleeved on the outside of the rotating support portion with a gap between them, and the first sidewall is located on the side of the second sidewall away from the rotating support portion. The first sidewall has a base 116b1 and a baffle 116b2. Preferably, the base 116b1 is parallel or substantially parallel to the second sidewall. The baffle 116b2 is inclined from the base 116b1 toward the second graphite cylinder side, and the baffle 116b2 is configured to protrude from the inner wall of the second graphite cylinder 114 (i.e., the orthographic projection of the second graphite cylinder 114 onto the base is between the orthographic projections of the baffle 116b2 and the second sidewall onto the base). In the axial direction of the housing, the inner wall of the second graphite cylinder 114 is between the baffle 116b2 and the second sidewall (i.e., the second graphite cylinder 114 is located within the opening). In the axial direction of the rotating support (i.e., in the z-direction), the height of the first sidewall is slightly higher than the height of the rotating support.

[0058] During epitaxial growth, purge gas is introduced into the gap (also called the gap / gap space) between the first graphite cylinder 113 and the second graphite cylinder 114 through the air inlet ring 120. Process gas is introduced into the reaction chamber (inside the second graphite cylinder 114) through the spray head. The pressure P1 in the gap between the first graphite cylinder 113 and the second graphite cylinder 114 (which can be estimated by the first pressure sensor) is greater than the pressure P2 inside the second graphite cylinder (which can be estimated by the second pressure sensor) inside the reaction chamber (inside the second graphite cylinder 114). The pressure P2 inside the graphite cylinder is used to purge the gas. After the purge gas is introduced into the gap between the first graphite cylinder 113 and the second graphite cylinder 114, it flows towards the rotating support side. At the same time, due to the pressure difference, part of the purge gas permeates and flows to the inner wall surface of the second graphite cylinder. Under the action of the suction ring 116 on the lower side, it flows towards the suction ring 116 side. In this way, a protective film (purge gas) is formed on the inner wall surface of the second graphite cylinder, preventing the process gas from permeating into the holes of the second graphite cylinder and affecting the subsequent epitaxial growth. During the process, pressure needs to be monitored in real time to ensure that P1 > P2 (e.g., 10-50 mbar higher, but not too high, as exceeding 50 mbar can easily cause turbulence to the process gas introduced into the spray head). Throughout the epitaxial process, the pressure and flow rate of the purge gas are adjusted in real time according to changes in P2 pressure to ensure the protective film remains effective despite pressure changes in the process chamber. This prevents direct contact between the process gas and the inner surface (i.e., the inner wall surface) of the second graphite cylinder, avoiding the formation of side reactants on the inner wall surface of the second graphite cylinder, thus extending the service life of both the first and second graphite cylinders. Preferably, during actual epitaxy, the purge gas is introduced first for a preset time (e.g., 5s, 10s), followed by the process gas. This allows some of the purge gas to permeate into the pores of the second graphite cylinder, preventing the process gas from penetrating into the pores and affecting subsequent epitaxial growth. Purge gas is continuously introduced at the end of the epitaxy process.

[0059] The rotating support 140 includes a support body 141, which is a hollow cylindrical shape and has a plurality of first vent holes 141a extending axially and penetrating through it. Preferably, the plurality of first vent holes 141a are evenly distributed along the circumference of the support body 141. A heat insulation plate 117 (heat insulation cylinder) is provided on the outer side of the support body 141. In the axial direction (z-direction) of the rotating support, the height of the heat insulation plate 117 is the same as or approximately the same as the height of the rotating support. The height of the first sidewall is slightly higher than the height of the rotating support, and the height of the second sidewall is lower than the height of the rotating support.

[0060] A support base plate 118 is mounted on the bottom of the support body 141, and the support base plate 118 is connected to the output shaft 130a of the drive component 130. The support base plate 118 is disc-shaped and has a second vent 118a extending radially upward therein. One end of the second vent 118a communicates with a third vent 131 on the drive component, and the other end communicates with a first vent 141a. The air inlet 131a of the third vent 131 is connected to a purge gas (such as argon) supply unit via a pipeline. A second heater 142 is provided inside the support body. The second heater 142 is a graphite heater. The drive component 130 is a magnetohydrodynamic motor.

[0061] The wafer support tray 150 includes a support frame 151 and a cover plate 152, the cover plate 152 being a hollow annular shape. The cover plate 152 is made of porous graphite material, preferably with a pore size between 100-1000 nm. The support frame 151 has a groove, the bottom of which is provided with a perforation 151a. The number of perforations 151a matches the number of first vent holes 141a. The support frame 151 has a protrusion 151b in the middle. The support frame 151 is placed on the side of the support body 141 away from the support base plate 118, and the vent of the first vent hole 141a is located within the perforation 151a. Preferably, the perforation 151a is elliptical. After the cover plate 152 is placed on the support frame 151, it is combined with the groove to form a uniform air groove. The recess formed by the cover plate 152 after being placed on the support frame 151 is used to place the wafer 200. The wafer can be a silicon carbide substrate, a silicon substrate or a gallium nitride substrate, and its size can be 6 inches, 8 inches or 12 inches.

[0062] During epitaxial growth, a purge gas (such as argon) with a certain pressure and flow rate is introduced through the inlet 131a of the third vent 131. The purge gas is transported to the gas distribution groove of the support frame 151 through the gas path composed of the support body 141 and the support base plate 118. The purge gas is evenly distributed in the gas distribution groove and then diffuses to the surface of the cover plate 152 through the medium gaps on the cover plate. In this way, by adjusting the pressure and flow rate of the purge gas, the protective film is evenly covered on the surface of the cover plate 152, avoiding the generation of side reactants on the surface of the cover plate 152. Due to the synergistic effect of the suction ring and the gas introduced by the spray device, the gas diffused from the cover plate 152 can be drawn into the suction ring 116 along the surface of the cover plate 152. At this time, the influence on the flow field of the process gas is very small (i.e., the influence is negligible). In the above embodiment, the purge gas is an inert gas, such as argon.

[0063] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. A silicon carbide epitaxial device, characterized in that, include: The reaction chamber includes: The housing includes a first graphite cylinder and a second graphite cylinder arranged coaxially from the outside to the inside. The first graphite cylinder and the second graphite cylinder are spaced apart. The second graphite cylinder is made of a porous medium with a pore size between 100-1000 nm. A spraying device is disposed on one side of the housing. The spraying device includes a spray head and an air inlet ring sleeved on the spray head. The air inlet ring is disposed on one side of the first graphite cylinder and the second graphite cylinder, and is used to introduce purging gas into the gap between the first graphite cylinder and the second graphite cylinder. The pressure in the gap between the first graphite cylinder and the second graphite cylinder is greater than the pressure in the second graphite cylinder. A drive component is disposed on the side of the housing opposite to the spraying device. The drive component is connected to a rotating support located inside the housing through the bottom plate of the housing. The side of the rotating support away from the drive component is used to place a wafer tray.

2. The silicon carbide epitaxial apparatus as described in claim 1, characterized in that, The air intake ring includes a base plate. One side of the base plate is disposed at one end of the first graphite cylinder and the second graphite cylinder, and this side has a first protrusion and a second protrusion extending along the axial direction of the base plate and toward the rotation support portion. The combination of the base plate and the first and second protrusions forms an air intake groove. An air inlet is provided on the base plate, and the air inlet is connected to the purge gas supply portion through an air intake pipe. A first pressure sensor is provided in the air intake pipe. The substrate has a third protrusion extending along the axial direction of the substrate on the side away from the first protrusion, and the third protrusion is annular.

3. The silicon carbide epitaxial apparatus as described in claim 1, characterized in that, The housing includes a first housing and a second housing arranged coaxially, with the first housing located closer to the spray device.

4. The silicon carbide epitaxial apparatus as described in claim 3, characterized in that, The first housing contains, from the outside in, a heat-insulating component, a first heater, a first graphite cylinder, and a second graphite cylinder, all coaxially arranged. The surface of the first graphite cylinder is coated with a silicon carbide coating.

5. The silicon carbide epitaxial apparatus as described in claim 3, characterized in that, The second housing contains a suction ring and a rotating support portion coaxially arranged from the outside to the inside. The suction ring includes a base, which is annular and has ventilation holes. One side of the base has a first sidewall and a second sidewall disposed opposite to each other. The first sidewall is located on the side of the second sidewall away from the rotating support portion. The combination of the first sidewall, the second sidewall, and the base forms a groove. A second pressure sensor is also provided inside the second housing to measure the air pressure inside the second graphite cylinder.

6. The silicon carbide epitaxial apparatus as described in claim 5, characterized in that, The first sidewall has a base and a baffle. The plane of the base is parallel to the plane of the second sidewall. The baffle is constructed to be inclined from the base toward the second graphite cylinder side.

7. The silicon carbide epitaxial apparatus as described in claim 1, characterized in that, At least one shielding part is provided in the gap between the first graphite cylinder and the second graphite cylinder, and the shielding part is used to slow down the flow rate of the purge gas in the gap between the first graphite cylinder and the second graphite cylinder.

8. The silicon carbide epitaxial apparatus as described in claim 7, characterized in that, The shielding portion is arranged circumferentially along the first graphite cylinder or the second graphite cylinder.

9. The silicon carbide epitaxial apparatus as described in claim 1, characterized in that, The rotating support includes a support body, which is a hollow cylindrical shape and has multiple first vent holes extending along its axial direction and penetrating through it. The multiple first vent holes are evenly distributed along the circumference of the support body. A support base plate is installed at the bottom of the support body, which has a second vent hole extending radially upward therein. The second vent hole connects a third vent hole on the drive component with the first vent hole. The air inlet of the third vent hole is connected to the purge gas supply unit through a pipeline.

10. The silicon carbide epitaxial apparatus as described in claim 9, characterized in that, The wafer tray includes a support frame and a cover plate; The cover plate is a hollow ring and is made of porous graphite material with a pore size between 100-1000 nm. The support frame has a groove, and the bottom of the groove is provided with a perforation. The number of perforations matches the number of the first ventilation holes. The support frame is placed on the side of the support body away from the support base plate. The cover plate is placed on the support frame and combines with the groove to form a uniform air groove.

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