A method for preparing a SiC coating graphite susceptor transition layer for semiconductors

Abstract

This invention discloses a method for preparing a SiC-coated graphite substrate transition layer for semiconductors. The method is implemented using a preparation device for this transition layer. The device includes a support base, with a vapor deposition reaction chamber located at the upper center of the support base. An air inlet is located at the upper center of the vapor deposition reaction chamber. A set of first suction pumps is installed on both the lower left and lower right sides of the vapor deposition reaction chamber. By incorporating a storage and exchange mechanism, the heat from the previous step is exchanged for the gas required for preheating in the next step, reducing heat loss and saving energy. Furthermore, by incorporating a first recovery mechanism and a second recovery mechanism, the efficiency of gas separation is improved, making the entire separation process more precise.

Description

Technical Field

[0001] This invention relates to the field of graphite substrate transition layer production equipment, and particularly to a method for preparing a SiC-coated graphite substrate transition layer for semiconductors. Background Technology

[0002] Chemical vapor deposition (CVD) is a chemical engineering technique that utilizes one or more gaseous compounds or elements containing thin-film elements to chemically react on a substrate surface to form a thin film. CVD is a relatively new technology for preparing inorganic materials, developed in recent decades. It is widely used for purifying substances, developing new crystals, and depositing various single-crystal, polycrystalline, or glassy inorganic thin-film materials. These materials can be oxides, sulfides, nitrides, carbides, or binary or multi-element inter-element compounds from groups III-V, II-IV, and IV-VI, and their physical properties can be precisely controlled through the vapor-phase doping deposition process. CVD has become a new field in inorganic synthetic chemistry.

[0003] SiC coatings possess excellent thermal shock resistance, oxidation resistance, resistance to airflow erosion, and low gas permeability. They exhibit good chemical and mechanical compatibility with graphite materials and remain stable above 1200℃. Furthermore, they demonstrate excellent resistance to acids and alkalis such as H2, HCl, and NH3. Therefore, in the epitaxial growth of semiconductor single crystal materials, SiC coatings can completely protect the graphite substrate material, improve its integrity, purify the growth environment, and extend its service life.

[0004] During the formation of the transition layer, the SiC coating needs to be repeatedly deposited in the chemical vapor deposition (CVD) reaction chamber. Referring to CN112391675B, silicon tetrachloride is first used as the precursor, argon as the dilution gas, and hydrogen as the carrier gas. The deposition temperature is 1000–1400℃, and the deposition time is 1–20 h to form the Si transition layer. Subsequently, methane is used as the carbon source, argon as the dilution gas, and the deposition temperature is 900–1200℃, with a deposition time of 1–20 h to form the pyrolytic carbon transition layer. Finally, silicon tetrachloride is used as the Si source, methane as the carbon source, argon as the dilution gas, and hydrogen as the carrier gas. The molar ratio of methane to silicon tetrachloride gradually changes from 1:0 to 1:1, and the deposition temperature is 1000–1200℃, with a deposition time of 5–50 h. To form a gradient SiC coating, the gases used in each deposition process, including the formation of the Si transition layer, the pyrolytic carbon transition layer, and the gradient SiC coating, require repeated purging of the residual gas in the reaction chamber before introducing the protective and carrier gases needed for the next deposition step. Each gas introduction step requires repeated preheating to the required temperature, consuming a significant amount of energy. Furthermore, the purged gas contains argon, the protective gas needed in each step. Traditional processes simply recover the argon and reuse it in the gas mixture, ignoring the heat carried by the gas and resulting in substantial heat loss. Therefore, we propose a method for preparing a graphite substrate transition layer for SiC coatings used in semiconductors. Summary of the Invention

[0005] The main objective of this invention is to provide a method for preparing a SiC-coated graphite substrate transition layer for semiconductors, which can effectively solve the problems of repeated gas preheating and large heat loss in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a transition layer for a SiC-coated graphite substrate used in semiconductors is disclosed. The method utilizes a preparation apparatus for preparing the transition layer. The apparatus includes a support base, a vapor deposition reaction chamber located at the upper center of the support base, an air inlet located at the upper center of the vapor deposition reaction chamber, a set of first suction pumps located on the lower left and lower right sides of the vapor deposition reaction chamber, a storage and exchange mechanism located at the output end of each first suction pump, a flow aid mechanism located on the upper part of the storage and exchange mechanism near the vapor deposition reaction chamber, a connecting pipe located at the upper center of each storage and exchange mechanism, a set of third electromagnetic control valves located within each connecting pipe, and a first recovery mechanism and a second recovery mechanism located at the other end of each connecting pipe. A third suction pump is located on the side of each first recovery mechanism furthest from the storage and exchange mechanism.

[0008] Preferably, the storage and exchange mechanism includes a storage chamber, a preheating rod, a spiral exchange tube, and a gas storage port. The preheating rod is fixedly installed in the middle of the inner cavity of the storage chamber, and the spiral exchange tube is spirally wound on the outer surface of the preheating rod. A gas storage port is fixedly installed on the lower part of the side of the storage chamber near the vapor deposition reaction chamber. The storage and exchange mechanism is fixedly installed on the support base through the storage chamber.

[0009] Preferably, a first electromagnetic control valve is fixedly installed at one end of the first air pump located in the vapor deposition reaction chamber, and a set of first air guide pipes is fixedly connected to the output end of the first air pump. The first air guide pipes pass through the storage chamber and are connected to the spiral exchange pipe.

[0010] Preferably, the flow-aiding mechanism includes a second air pump, a second air guide pipe, and a second electromagnetic control valve. A set of second air guide pipes is fixedly connected to one end of the second air pump away from the storage chamber. The other end of the second air guide pipes is connected to the inner cavity of the vapor deposition reaction chamber. A set of second electromagnetic control valves is fixedly installed at both ends of the second air guide pipes located in the inner cavity of the vapor deposition reaction chamber. The flow-aiding mechanism is fixedly installed on the upper part of the outer wall of the storage chamber via the second air pump.

[0011] Preferably, the first recovery mechanism includes a first recovery chamber, a condenser plate, a first gas density detector, a positioning rod, a top plate, and a limiting block. The condenser plate is fixedly installed in the middle right side of the first recovery chamber, the first gas density detector is fixedly installed in the upper left side of the first recovery chamber, the positioning rod is fixedly installed in the middle bottom of the first recovery chamber, the top plate is movably sleeved on the outer surface of the positioning rod, and the limiting block is fixedly installed at the upper end of the positioning rod. The first gas density detector is electrically connected to the third vacuum pump.

[0012] Preferably, the second recovery mechanism includes a second recovery chamber, a second gas density detector, and a fourth air pump. The second gas density detector is fixedly installed on the upper right side of the inner cavity of the second recovery chamber, and the fourth air pump is fixedly installed on the upper right side of the outer surface of the second recovery chamber.

[0013] Preferably, two sets of symmetrically distributed guide pipes are fixedly installed on the bottom wall of the first recovery chamber. Each guide pipe is equipped with a fifth electromagnetic control valve, and the lower ends of both sets of guide pipes are connected to a liquid accumulation tank.

[0014] Preferably, a set of limiting grooves is provided on both the left and right sides of the outer surface of the positioning rod, and an I-shaped through groove is provided in the middle of the upper part of the top plate. A set of protruding apexes are fixedly installed on both the left and right sides of the upper part of the top plate. The I-shaped through groove and the limiting groove are slidably connected to connect the top plate and the positioning rod together.

[0015] Preferably, a placement groove is provided in the middle of the left and right sides of the lower end of the limiting block, and a contact limiter is fixedly installed in the placement groove. The placement groove is located directly above the apex of the protrusion, and the contact limiter is electrically connected to the fifth electromagnetic control valve.

[0016] Preferably, the lower middle parts of the third and fourth air pumps are respectively fixedly connected to a first argon extraction tube and a second argon extraction tube, and a set of fourth electromagnetic control valves are respectively fixedly installed inside the first and second argon extraction tubes.

[0017] Preferably, the preparation method specifically includes the following steps:

[0018] S1. Preparation of Si transition layer: Silicon tetrachloride, argon and carrier hydrogen are introduced into the gas inlet to raise the temperature in the gas phase deposition reaction chamber to 1000-1400℃ and deposit for 1-20 hours to form Si transition layer.

[0019] S2. Extracting residual gas generated from the Si transition layer: Start the first pump on the left to transport the residual gas in the vapor deposition reaction chamber, including silicon tetrachloride, argon and hydrogen, to the storage and exchange mechanism on the left through the first gas guide pipe. The gas extracted by the first pump on the left is heat-exchanged with the storage and exchange mechanism on the left. By opening the first electromagnetic control valve on the left, the storage and exchange mechanism on the left is pre-filled with silicon tetrachloride, methane, argon and hydrogen required to form the pyrolytic carbon transition layer through the gas storage port. The gas extracted by the first pump on the left is heat-exchanged with the gas pre-filled in the storage chamber on the left through the spiral exchange pipe. Then, open the third electromagnetic control valve on the left so that the gas extracted in step S1 enters the first recovery mechanism through the connecting pipe. The gas entering at this time includes silicon tetrachloride, argon and carrier gas hydrogen.

[0020] Separating residual gases from the Si transition layer: The gas extracted by the first pump on the left side of step S2 is separated. The incoming gas includes silicon tetrachloride, argon, and hydrogen as the carrier gas. The density of these three gases is argon > silicon tetrachloride > hydrogen. After the gas from step S2 enters the first recovery chamber, the third electromagnetic control valve on the left side is closed, sealing the entire first recovery chamber on the left. The condenser plate is opened to condense and precipitate the incoming gas. Due to the density difference, hydrogen rises to the top of the first recovery chamber, while argon remains at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate. Below room temperature, silicon tetrachloride is liquid. At this point, the third pump is opened to remove the hydrogen from the upper part of the first recovery chamber. When the density of the upper part of the first recovery chamber detected by the first gas density detector is consistent with the density of argon, it indicates that the hydrogen has been completely extracted. The third pump is then shut off to extract the hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber after liquefaction. As more and more liquid silicon tetrachloride accumulates, the liquid surface formed by the silicon tetrachloride causes the top plate to rise. When the top plate rises to the limit position along the positioning rod, the apex of the protrusion on the top plate just contacts the contact limiter below the limit block. At this time, the contact limiter sends a signal to the fifth electromagnetic control valve, which opens, allowing the liquid silicon tetrachloride to flow into the accumulation tank. The fourth electromagnetic control valve is then opened, and the third pump is started to extract the stored argon through the first argon extraction pipe for recycling.

[0021] To form a pyrolytic carbon transition layer: Start the second air pump in the flow aid mechanism on the left, open the second electromagnetic control valve on the left, and send the gas in the storage chamber on the left, which has undergone heat exchange, into the vapor phase deposition reaction chamber for deposition reaction. Raise the temperature in the vapor phase deposition reaction chamber to 900-1200℃ to form a pyrolytic carbon transition layer.

[0022] Extracting residual gas from the vapor deposition reaction chamber for forming the pyrolytic carbon transition layer: The first pump on the right is activated to transport the residual gas in the vapor deposition reaction chamber, including argon, methane, and hydrogen, through the first gas guide pipe to the storage and exchange mechanism on the right. The gas extracted by the first pump on the right undergoes heat exchange with the storage and exchange mechanism on the right. By opening the first electromagnetic control valve on the right, the storage and exchange mechanism on the right is pre-filled with the gas required for forming the gradient SiC coating, including silicon tetrachloride, argon, methane, and hydrogen, through the gas storage port. The gas extracted by the first pump on the right undergoes heat exchange with the gas pre-filled in the storage chamber on the right through the spiral exchange pipe. Then, the third electromagnetic control valve on the right is opened. The gas extracted in step S4 enters the second recovery mechanism through the connecting pipe on the right. The gas entering the second recovery mechanism includes methane, argon, and hydrogen, with the density order being argon > methane > hydrogen. Hydrogen rises to the top of the second recovery chamber, methane is in the middle, and argon is at the bottom. At this point, the third pump is turned on to extract the hydrogen and methane from the top of the second recovery chamber. When the density of the upper part of the second recovery chamber detected by the second gas density detector is the same as the density of argon, it indicates that the hydrogen and methane have been extracted. The third pump is turned off to extract hydrogen, and the fourth electromagnetic control valve on the right is turned on to start the fourth pump to extract argon for recycling.

[0023] To form a gradient SiC coating: Start the second air pump in the flow aid mechanism on the right, open the second electromagnetic control valve on the right, and send the gas in the storage chamber on the right, which has undergone heat exchange, into the vapor deposition reaction chamber for deposition reaction. Raise the temperature in the vapor deposition reaction chamber to 1000-1200℃, and gradually change the molar ratio of methane to silicon tetrachloride gas from 1:0 to 1:1. The deposition time is 5-50h to form a gradient SiC coating.

[0024] Extracting and processing the residual gas generated during the formation of the gradient SiC coating: Start the first pump on the left to separate the gas extracted by the first pump in step S6. The incoming gas includes silicon tetrachloride, argon, methane, and hydrogen. The density of these four gases is in the order of argon > silicon tetrachloride > methane > hydrogen. After the gas from step S6 enters the first recovery chamber, close the third electromagnetic control valve on the left, sealing the entire first recovery chamber. Open the condenser plate to condense and precipitate the incoming gas. Due to the density order, hydrogen rises to the top of the first recovery chamber, methane is in the middle, and argon is at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate. Below room temperature, silicon tetrachloride is liquid. At this point, open the third pump... The gas pump extracts hydrogen and methane from the upper part of the first recovery chamber. When the density detected by the first gas density detector in the upper part of the first recovery chamber is consistent with the density of argon, it indicates that the hydrogen has been completely extracted. The third gas pump is then shut off to extract hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber after liquefaction. As more and more liquid silicon tetrachloride accumulates, the liquid surface caused the top plate to rise. When the top plate rises to the limit position along the positioning rod, the protruding apex of the top plate just contacts the contact limiter below the limit block. At this time, the contact limiter sends a signal to the fifth electromagnetic control valve, which opens, allowing the liquid silicon tetrachloride to flow into the accumulation tank. The fourth electromagnetic control valve is then opened, and the third gas pump is started to extract the stored argon through the first argon extraction pipe for recycling.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. In this invention, a storage and exchange mechanism is set up, which includes a storage chamber, a preheating rod, a spiral exchange tube, and a gas storage port. The residual gas generated in each step is transported to the spiral exchange tube by a first air pump, and heat is exchanged with the gas needed for the next step, which is pre-filled in the storage chamber. The heat from the previous step is exchanged with the gas needed for the preheating of the next step, which reduces the loss of gas heat and utilizes the heat generated by the entire deposition reaction, saving the energy required for preheating the gas.

[0027] 2. By setting up a first recovery mechanism and a second recovery mechanism, gases containing silicon tetrachloride are sent to the first recovery mechanism and the second recovery mechanism respectively for recovery in steps and in components, thereby improving the efficiency of gas separation and also fully separating the useful substances in the residual gas, making the entire separation process more refined. Attached Figure Description

[0028] Figure 1 This is an overall front view of the equipment used in the method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to the present invention.

[0029] Figure 2 This is a cross-sectional view of the first recycling mechanism of the equipment used in the method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to the present invention.

[0030] Figure 3 This is a front view of the limiting block of the equipment used in the method for preparing a SiC coated graphite substrate transition layer for semiconductors according to the present invention.

[0031] Figure 4 This is a schematic diagram of the positioning rod and top block of the equipment used in the method for preparing a SiC coated graphite substrate transition layer for semiconductors according to the present invention.

[0032] Figure 5 This is an enlarged view of point A of the equipment used in the method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to the present invention.

[0033] In the diagram: 1. Support base; 2. Vapor deposition reaction chamber; 3. Air inlet; 4. First vacuum pump; 41. First electromagnetic control valve; 42. First gas guide pipe; 5. Storage and exchange mechanism; 51. Storage chamber; 52. Preheating rod; 53. Spiral exchange pipe; 54. Gas storage port; 6. Connecting pipe; 61. Third electromagnetic control valve; 7. Flow aid mechanism; 71. Second vacuum pump; 72. Second gas guide pipe; 73. Second electromagnetic control valve; 8. First recovery mechanism; 81. First recovery chamber; 811. Flow guide pipe; 812. Fifth electromagnetic control valve. Magnetic control valve; 813, liquid accumulation tank; 82, condenser plate; 83, first gas density detector; 84, positioning rod; 841, limiting slide groove; 85, top plate; 851, I-shaped through groove; 852, protruding apex; 86, limiting block; 861, placement groove; 862, contact limiter; 9, second recovery mechanism; 91, second recovery chamber; 92, second gas density detector; 93, fourth vacuum pump; 931, second argon extraction tube; 10, third vacuum pump; 101, first argon extraction tube; 11, fourth electromagnetic control valve. Detailed Implementation

[0034] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0035] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] like Figure 1-5 As shown, a method for preparing a transition layer for a SiC-coated graphite substrate in semiconductors is disclosed. This method is implemented using a preparation device for the SiC-coated graphite substrate transition layer. The device includes a support base 1, a vapor deposition reaction chamber 2 located at the upper center of the support base 1, an air inlet 3 located at the upper center of the vapor deposition reaction chamber 2, a set of first vacuum pumps 4 located on the lower left and lower right sides of the vapor deposition reaction chamber 2, a set of storage and exchange mechanisms 5 located at the output end of each of the first vacuum pumps 4, a set of flow aid mechanisms 7 located on the upper side of each storage and exchange mechanism 5 near the vapor deposition reaction chamber 2, a set of connecting pipes 6 located at the upper center of each storage and exchange mechanism 5, a set of third electromagnetic control valves 61 located within each connecting pipe 6, and a set of first recovery mechanisms 8 and second recovery mechanisms 9 located at the other end of each connecting pipe 6. A set of third vacuum pumps 10 located on the side of each first recovery mechanism 8 away from the storage and exchange mechanism 5.

[0038] The storage and exchange mechanism 5 includes a storage chamber 51, a preheating rod 52, a spiral exchange tube 53, and a gas storage port 54. The preheating rod 52 is fixedly installed in the middle of the inner cavity of the storage chamber 51, and the spiral exchange tube 53 is spirally wound on the outer surface of the preheating rod 52. The gas storage port 54 is fixedly installed on the lower part of the side of the storage chamber 51 near the vapor deposition reaction chamber 2. The storage and exchange mechanism 5 is fixedly installed on the support base 1 through the storage chamber 51, so as to facilitate the exchange of heat in the residual gas generated in the previous step of each process to the gas to be used in the next step, thus preheating the gas required for the next step.

[0039] The first air pump 4 is located in the vapor deposition reaction chamber 2 and is fixedly equipped with a first electromagnetic control valve 41 at one end. The output end of the first air pump 4 is fixedly connected to a set of first air guide pipes 42. The first air guide pipes 42 pass through the storage chamber 51 and are connected to the spiral exchange pipe 53, so as to extract the residual gas in the vapor deposition reaction chamber 2 and send it to the corresponding storage and exchange mechanism 5.

[0040] The flow-aiding mechanism 7 includes a second air pump 71, a second air guide pipe 72, and a second electromagnetic control valve 73. A set of second air guide pipes 72 is fixedly connected to one end of the second air pump 71 away from the storage chamber 51. The other end of the second air guide pipes 72 is connected to the inner cavity of the vapor deposition reaction chamber 2. A set of second electromagnetic control valves 73 is fixedly installed at both ends of the second air guide pipes 72 located in the inner cavity of the vapor deposition reaction chamber 2. The flow-aiding mechanism 7 is fixedly installed on the upper part of the outer wall of the storage chamber 51 through the second air pump 71, which facilitates the delivery of the gas required for different steps to the vapor deposition reaction chamber 2.

[0041] The first recovery mechanism 8 includes a first recovery chamber 81, a condenser plate 82, a first gas density detector 83, a positioning rod 84, a top plate 85, and a limiting block 86. The condenser plate 82 is fixedly installed in the middle right side of the inner cavity of the first recovery chamber 81. The first gas density detector 83 is fixedly installed in the upper left side of the inner cavity of the first recovery chamber 81. The positioning rod 84 is fixedly installed in the middle bottom end of the first recovery chamber 81. The top plate 85 is movably sleeved on the outer surface of the positioning rod 84. The limiting block 86 is fixedly installed at the upper end of the positioning rod 84. The first gas density detector 83 is electrically connected to the third vacuum pump 10 to facilitate the separation of residual gas mixed with silicon tetrachloride.

[0042] The second recovery mechanism 9 includes a second recovery chamber 91, a second gas density detector 92, and a fourth air pump 93. The second gas density detector 92 is fixedly installed on the upper right side of the inner cavity of the second recovery chamber 91, and the fourth air pump 93 is fixedly installed on the upper right side of the outer surface of the second recovery chamber 91 to facilitate the separation of residual gases that do not contain silicon tetrachloride.

[0043] Two sets of symmetrically distributed guide pipes 811 are fixedly installed on the bottom wall of the first recovery chamber 81. Each guide pipe 811 is equipped with a fifth electromagnetic control valve 812. The lower ends of the two sets of guide pipes 811 are connected to a liquid collection tank 813 to facilitate the collection of liquefied silicon tetrachloride liquid.

[0044] A set of limiting grooves 841 are provided on both the left and right sides of the outer surface of the positioning rod 84. An I-shaped through groove 851 is provided in the middle of the upper end of the top plate 85. A set of protruding apexes 852 are fixedly installed on both the left and right sides of the upper part of the top plate 85. The I-shaped through groove 851 and the limiting groove 841 are slidably connected to the top plate 85 and the positioning rod 84, so that when the liquefied silicon tetrachloride liquid level rises to the limit position, the liquefied silicon tetrachloride can be discharged into the liquid accumulation tank 813 in time.

[0045] The lower end of the limit block 86 has a placement groove 861 in the middle of the left and right sides. A contact limiter 862 is fixedly installed in the placement groove 861, and the placement groove 861 is located directly above the protrusion apex 852. The contact limiter 862 is electrically connected to the fifth electromagnetic control valve 812, so that when the liquefied silicon tetrachloride liquid level rises to the limit position, the liquefied silicon tetrachloride is discharged into the liquid accumulation tank 813 in time.

[0046] The third pump 10 and the fourth pump 93 are respectively fixedly connected to the middle of the lower side of the first argon extraction tube 101 and the second argon extraction tube 931. A set of fourth electromagnetic control valves 11 are fixedly installed in the first argon extraction tube 101 and the second argon extraction tube 931 to facilitate the separation of argon gas from the residual gas and the recycling of argon gas.

[0047] The preparation method specifically includes the following steps:

[0048] S1. Preparation of Si transition layer: Silicon tetrachloride, argon and carrier gas hydrogen are introduced into the gas inlet 3 to raise the temperature in the vapor deposition reaction chamber 2 to 1000-1400℃ and deposit for 1-20 hours to form Si transition layer.

[0049] S2. Extracting residual gas generated from the Si transition layer: Start the first pump 4 on the left to transport the residual gas in the vapor deposition reaction chamber 2, including silicon tetrachloride, argon and hydrogen, through the first gas guide pipe 42 to the storage and exchange mechanism 5 on the left. The gas extracted by the first pump 4 on the left is heat-exchanged with the storage and exchange mechanism 5 on the left. By opening the first electromagnetic control valve 41 on the left, the storage and exchange mechanism 5 on the left is pre-filled with silicon tetrachloride, methane, argon and hydrogen required to form the pyrolytic carbon transition layer through the gas storage port 54. The gas extracted by the first pump 4 on the left is heat-exchanged with the gas pre-filled in the storage chamber 51 on the left through the spiral exchange pipe 53. Then open the third electromagnetic control valve 61 on the left so that the gas extracted in step S1 enters the first recovery mechanism 8 through the connecting pipe 6. The gas entering at this time includes silicon tetrachloride, argon and carrier gas hydrogen.

[0050] S3. Separating the residual gas generated by the Si transition layer: Separate the gas extracted by the first pump 4 on the left side of step S2. The gas entering at this time includes silicon tetrachloride, argon, and carrier gas hydrogen. The density of these three gases is argon > silicon tetrachloride > hydrogen. After the gas from step S2 enters the first recovery chamber 81, close the third electromagnetic control valve 61 on the left side to keep the entire first recovery chamber 81 on the left side closed. Open the condenser plate 82 to condense and precipitate the entering gas. Due to the density relationship, hydrogen will rise to the top of the first recovery chamber 81, while argon will be at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate 82. Below room temperature, silicon tetrachloride is liquid. At this time, open the third pump 10 to extract the hydrogen from the top of the first recovery chamber 81. When the density of the upper part of the first recovery chamber 81 detected by detector 83 is the same as the density of argon, it indicates that the hydrogen has been completely extracted. The third pumping pump 10 is then turned off to extract the hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber 81 after liquefaction. As more and more liquid silicon tetrachloride accumulates, the liquid surface formed by the silicon tetrachloride causes the top plate 85 to move upward. When the top plate 85 rises to the limit position along the positioning rod 84, the protruding apex 852 on the top plate 85 just contacts the contact limiter 862 below the limit block 86. At this time, the contact limiter 862 sends a signal to the fifth electromagnetic control valve 812. The fifth electromagnetic control valve 812 opens, allowing the liquid silicon tetrachloride to flow into the liquid accumulation tank 813. The fourth electromagnetic control valve 11 is opened, and the third pumping pump 10 is started to extract the stored argon through the first argon extraction pipe 101 for recycling.

[0051] S4. Forming a pyrolytic carbon transition layer: Start the second air pump 71 in the flow aid mechanism 7 on the left, open the second electromagnetic control valve 73 on the left, and send the gas in the storage chamber 51 on the left, which has undergone heat exchange, into the vapor deposition reaction chamber 2 for deposition reaction, raising the temperature in the vapor deposition reaction chamber 2 to 900-1200℃, and forming a pyrolytic carbon transition layer.

[0052] S5. Extracting residual gas from the vapor deposition reaction chamber 2 for forming the pyrolytic carbon transition layer: Start the first suction pump 4 on the right to transport the residual gas in the vapor deposition reaction chamber 2, including argon, methane, and hydrogen, through the first gas guide pipe 42 to the storage and exchange mechanism 5 on the right. The gas extracted by the first suction pump 4 on the right exchanges heat with the storage and exchange mechanism 5 on the right. By opening the first electromagnetic control valve 41 on the right, the storage and exchange mechanism 5 on the right is pre-filled with the gas required for forming the gradient SiC coating, including silicon tetrachloride, argon, methane, and hydrogen, through the gas storage port 54. The gas extracted by the first suction pump 4 on the right exchanges heat with the gas pre-filled in the storage chamber 51 on the right through the spiral exchange pipe 53. Then, open the third electromagnetic control valve on the right. 61. The gas extracted in step S4 enters the second recovery mechanism 9 through the connecting pipe 6 on the right. At this time, the gas entering the second recovery mechanism 9 includes methane, argon and hydrogen. The density relationship is argon > methane > hydrogen. Hydrogen will rise to the top of the entire second recovery chamber 91, methane is in the middle, and argon is at the bottom. At this time, the third pump 10 is turned on to extract the hydrogen and methane in the upper part of the second recovery chamber 91. When the density of the upper part of the second recovery chamber 91 detected by the second gas density detector 92 is the same as the density of argon, it indicates that the hydrogen and methane have been extracted. The extraction of hydrogen by the third pump 10 is turned off, the fourth electromagnetic control valve 11 on the right is turned on, and the fourth pump 93 is started to extract argon for recycling.

[0053] S6. Forming a gradient SiC coating: Start the second air pump 71 in the flow aid mechanism 7 on the right side, open the second electromagnetic control valve 73 on the right side, and send the gas in the storage chamber 51 on the right side, which has undergone heat exchange, into the vapor deposition reaction chamber 2 for deposition reaction. Raise the temperature in the vapor deposition reaction chamber 2 to 1000-1200℃, and gradually change the molar ratio of methane and silicon tetrachloride gas from 1:0 to 1:1. The deposition time is 5-50h, and a gradient SiC coating is formed.

[0054] S7. Extracting and processing residual gases generated during the formation of the gradient SiC coating: Start the first pump 4 on the left to separate the gas extracted by the first pump 4 in step S6. The gas entering at this time includes silicon tetrachloride, argon, methane, and hydrogen. The density of these four gases is argon > silicon tetrachloride > methane > hydrogen. After the gas from step S6 enters the first recovery chamber 81, close the third electromagnetic control valve 61 on the left to close the entire first recovery chamber 81 on the left. Open the condenser plate 82 to condense and precipitate the entering gas. Due to the density relationship, hydrogen will rise to the top of the first recovery chamber 81, methane will be in the middle, and argon will be at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate 82. Silicon tetrachloride is liquid below room temperature. At this time, open the third pump 10 to extract the gas from the top of the first recovery chamber 81. Hydrogen and methane are extracted. When the density of the upper part of the first recovery chamber 81 detected by the first gas density detector 83 is consistent with the density of argon, it indicates that the hydrogen has been completely extracted. The third pumping pump 10 is then shut off to extract hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber 81 after liquefaction. As more and more liquid silicon tetrachloride accumulates, the liquid surface formed by the silicon tetrachloride causes the top plate 85 to move upward. When the top plate 85 rises to the limit position along the positioning rod 84, the protruding apex 852 on the top plate 85 just contacts the contact limiter 862 below the limit block 86. At this time, the contact limiter 862 sends a signal to the fifth electromagnetic control valve 812, which opens, allowing the liquid silicon tetrachloride to flow into the liquid accumulation tank 813. The fourth electromagnetic control valve 11 is then opened, and the third pumping pump 10 is started to extract the stored argon through the first argon extraction pipe 101 for recycling.

[0055] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a SiC-coated graphite substrate transition layer for semiconductors, characterized in that: The method for preparing the transition layer of the SiC-coated graphite substrate for semiconductors is implemented by a preparation device for the transition layer of the SiC-coated graphite substrate for semiconductors. The preparation device for the transition layer of the SiC-coated graphite substrate for semiconductors includes a support base (1), a vapor deposition reaction chamber (2) is provided in the middle of the upper end of the support base (1), an air inlet (3) is provided in the middle of the upper end of the vapor deposition reaction chamber (2), and a set of first suction pumps (4) are provided on the lower left and lower right sides of the vapor deposition reaction chamber (2). The output ends of the first suction pumps (4) are each provided with There is a set of storage and exchange mechanisms (5). Each storage and exchange mechanism (5) is equipped with a set of flow aid mechanisms (7) on the upper part of the side of the storage and exchange mechanism (5) near the vapor deposition reaction chamber (2). Each storage and exchange mechanism (5) is equipped with a set of connecting pipes (6) in the middle of the upper end. Each connecting pipe (6) is equipped with a set of third electromagnetic control valves (61). Each connecting pipe (6) is equipped with a set of first recovery mechanisms (8) and second recovery mechanisms (9) respectively. Each first recovery mechanism (8) is equipped with a set of third vacuum pumps (10) on the side away from the storage and exchange mechanism (5). The storage and exchange mechanism (5) includes a storage chamber (51), a preheating rod (52), a spiral exchange tube (53), and a gas storage port (54). The preheating rod (52) is fixedly installed in the middle of the inner cavity of the storage chamber (51), and the spiral exchange tube (53) is spirally wound on the outer surface of the preheating rod (52). The gas storage port (54) is fixedly installed on the lower part of the side of the storage chamber (51) near the vapor deposition reaction chamber (2). The storage and exchange mechanism (5) is fixedly installed on the support base (1) through the storage chamber (51). The flow aid mechanism (7) includes a second pump. The second air pump (71), the second air guide pipe (72), and the second electromagnetic control valve (73) are provided. The second air pump (71) is fixedly connected to a set of second air guide pipes (72) at one end away from the storage chamber (51). The other end of the second air guide pipe (72) is connected to the inner cavity of the vapor deposition reaction chamber (2). A set of second electromagnetic control valves (73) are fixedly installed at the end of the second air guide pipe (72) located in the inner cavity of the vapor deposition reaction chamber (2). The flow aid mechanism (7) is fixedly installed on the upper part of the outer wall of the storage chamber (51) through the second air pump (71).

2. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 1, characterized in that: The first air pump (4) is located in the vapor deposition reaction chamber (2) and a first electromagnetic control valve (41) is fixedly installed at one end. The output end of the first air pump (4) is fixedly connected to a set of first air guide pipes (42). The first air guide pipes (42) pass through the storage chamber (51) and are connected to the spiral exchange pipe (53).

3. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 2, characterized in that: The first recovery mechanism (8) includes a first recovery chamber (81), a condenser plate (82), a first gas density detector (83), a positioning rod (84), a top plate (85), and a limiting block (86). The condenser plate (82) is fixedly installed in the middle right side of the inner cavity of the first recovery chamber (81). The first gas density detector (83) is fixedly installed in the upper left side of the inner cavity of the first recovery chamber (81). The positioning rod (84) is fixedly installed in the middle bottom of the first recovery chamber (81). The top plate (85) is movably sleeved on the outer surface of the positioning rod (84). The limiting block (86) is fixedly installed at the upper end of the positioning rod (84). The first gas density detector (83) is electrically connected to the third vacuum pump (10).

4. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 3, characterized in that: The second recovery mechanism (9) includes a second recovery chamber (91), a second gas density detector (92) and a fourth air pump (93). The second gas density detector (92) is fixedly installed on the upper right side of the inner cavity of the second recovery chamber (91), and the fourth air pump (93) is fixedly installed on the upper right side of the outer surface of the second recovery chamber (91).

5. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 4, characterized in that: The bottom wall of the first recovery chamber (81) is fixedly equipped with two sets of symmetrically distributed guide pipes (811). Each guide pipe (811) is equipped with a fifth electromagnetic control valve (812). The lower ends of the two sets of guide pipes (811) are connected to a liquid accumulation tank (813).

6. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 5, characterized in that: The positioning rod (84) has a set of limiting grooves (841) on both the left and right sides of its outer surface. The top plate (85) has an I-shaped through groove (851) in the middle of its upper end. The top plate (85) has a set of protruding apexes (852) fixedly installed on both the left and right sides of its upper end. The I-shaped through groove (851) and the limiting groove (841) are slidably connected to connect the top plate (85) and the positioning rod (84) together.

7. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 6, characterized in that: The lower end of the limiting block (86) has a placement groove (861) in the middle of the left and right sides. A contact limiter (862) is fixedly installed in the placement groove (861), and the placement groove (861) is located directly above the protrusion apex (852). The contact limiter (862) is electrically connected to the fifth electromagnetic control valve (812).

8. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 7, characterized in that: The third air pump (10) and the fourth air pump (93) are respectively fixedly connected to the middle part of the lower side of the first argon extraction tube (101) and the second argon extraction tube (931). A set of fourth electromagnetic control valves (11) are respectively fixedly installed in the first argon extraction tube (101) and the second argon extraction tube (931).

9. The method for preparing a SiC-coated graphite substrate transition layer for semiconductors according to claim 8, characterized in that, The preparation method specifically includes the following steps: S1. Preparation of Si transition layer: Silicon tetrachloride, argon and carrier hydrogen are introduced into the gas inlet (3) to raise the temperature in the vapor deposition reaction chamber (2) to 1000-1400°C and deposit for 1-20 hours to form Si transition layer; S2. Extracting residual gas generated by the Si transition layer: Start the first pump (4) on the left to transport the residual gas in the vapor deposition reaction chamber (2), including silicon tetrachloride, argon and hydrogen, through the first gas guide pipe (42) to the storage and exchange mechanism (5) on the left. The gas extracted by the first pump (4) on the left is heat-exchanged with the storage and exchange mechanism (5) on the left. By opening the first electromagnetic control valve (41) on the left, the storage and exchange mechanism (5) on the left is filled with silicon tetrachloride, methane, argon and hydrogen required to form the pyrolytic carbon transition layer through the gas storage port (54). The gas extracted by the first pump (4) on the left is heat-exchanged with the gas filled in the storage chamber (51) on the left through the spiral exchange pipe (53). Then, the third electromagnetic control valve (61) on the left is opened so that the gas extracted in step S1 enters the first recovery mechanism (8) through the connecting pipe (6). The gas entering at this time includes silicon tetrachloride, argon and carrier gas hydrogen. S3. Separate the residual gas generated by the Si transition layer: Separate the gas extracted by the first pump (4) on the left side of step S2. The gas entering at this time includes silicon tetrachloride, argon and carrier gas hydrogen. The density of these three gases is argon > silicon tetrachloride > hydrogen. After the gas after step S2 enters the first recovery chamber (81), close the third electromagnetic control valve (61) on the left side to keep the entire first recovery chamber (81) on the left side closed. Open the condenser plate (82) to condense and precipitate the gas entering. Due to the density relationship, hydrogen will rise to the top of the entire first recovery chamber (81), while argon will be at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate (82). Silicon tetrachloride is liquid below room temperature. At this time, open the third pump (10) to extract the hydrogen in the upper part of the first recovery chamber (81). When the first gas density detector (83) detects When the density of the upper part of the first recovery chamber (81) is the same as that of argon, it indicates that the hydrogen has been completely pumped out. The third pumping pump (10) is turned off to pump out the hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber (81) after liquefaction. As more and more liquid silicon tetrachloride is added, the liquid surface formed by silicon tetrachloride causes the top plate (85) to move upward. When the top plate (85) rises to the limit position along the positioning rod (84), the protruding apex (852) on the top plate (85) just contacts the contact limiter (862) below the limit block (86). At this time, the contact limiter (862) sends a signal to the fifth electromagnetic control valve (812). The fifth electromagnetic control valve (812) opens, allowing the liquid silicon tetrachloride to flow into the liquid accumulation tank (813). The fourth electromagnetic control valve (11) is opened, and the third pumping pump (10) is started to extract the stored argon through the first argon extraction pipe (101) for recycling. S4. Forming a pyrolytic carbon transition layer: Start the second air pump (71) in the flow aid mechanism (7) in the left position, open the second electromagnetic control valve (73) in the left position, and send the gas in the storage chamber (51) in the left position after heat exchange into the vapor deposition reaction chamber (2) for deposition reaction, and raise the temperature in the vapor deposition reaction chamber (2) to 900~1200°C to form a pyrolytic carbon transition layer. S5. Extracting residual gas from the vapor deposition reaction chamber (2) for forming the pyrolytic carbon transition layer: Start the first pump (4) on the right to transport the residual gas in the vapor deposition reaction chamber (2), including argon, methane and hydrogen, through the first gas guide pipe (42) to the storage and exchange mechanism (5) on the right. The gas extracted by the first pump (4) on the right is heat-exchanged with the storage and exchange mechanism (5) on the right. By opening the first electromagnetic control valve (41) on the right, the storage and exchange mechanism (5) on the right is pre-filled with the gas required to form the gradient SiC coating through the gas storage port (54), including silicon tetrachloride, argon, methane and hydrogen. The gas extracted by the first pump (4) on the right is heat-exchanged with the gas pre-filled in the storage chamber (51) on the right through the spiral exchange pipe (53). Then, the third electromagnetic control valve on the right is opened. Valve (61) allows the gas extracted in step S4 to enter the second recovery mechanism (9) through the connecting pipe (6) on the right. At this time, the gas entering the second recovery mechanism (9) includes methane, argon and hydrogen. The density relationship is argon > methane > hydrogen. Hydrogen will rise to the top of the entire second recovery chamber (91), methane is in the middle, and argon is at the bottom. At this time, the third pump (10) is turned on to extract the hydrogen and methane in the upper part of the second recovery chamber (91). When the density of the upper part of the second recovery chamber (91) detected by the second gas density detector (92) is consistent with the density of argon, it indicates that the hydrogen and methane have been extracted. The third pump (10) is turned off to extract hydrogen. The fourth electromagnetic control valve (11) on the right is turned on to start the fourth pump (93) to extract argon for recycling. S6. Forming a gradient SiC coating: Start the second air pump (71) in the flow aid mechanism (7) on the right side, open the second electromagnetic control valve (73) on the right side, and send the gas in the storage chamber (51) on the right side after heat exchange into the vapor deposition reaction chamber (2) for deposition reaction. Raise the temperature in the vapor deposition reaction chamber (2) to 1000-1200°C, and gradually change the molar ratio of methane and silicon tetrachloride gas from 1:0 to 1:

1. The deposition time is 5-50h, and a gradient SiC coating is formed. S7. Extracting and processing the residual gas generated during the formation of the gradient SiC coating: Start the first pump (4) on the left to separate the gas extracted by the first pump (4) in step S6. The gas entering at this time includes silicon tetrachloride, argon, methane and hydrogen. The density of these four gases is argon > silicon tetrachloride > methane > hydrogen. After the gas after step S6 enters the first recovery chamber (81), close the third electromagnetic control valve (61) on the left to keep the first recovery chamber (81) on the left closed. Open the condenser plate (82) to condense and precipitate the gas. Due to the density relationship, hydrogen will rise to the top of the first recovery chamber (81), methane will be in the middle, and argon will be at the bottom. Silicon tetrachloride becomes liquid under the action of the condenser plate (82). Silicon tetrachloride is liquid below room temperature. At this time, open the third pump (10) to extract the hydrogen and methane in the upper part of the first recovery chamber (81). When the density detected by the first gas density detector (83) in the upper part of the first recovery chamber (81) is consistent with the density of argon, it indicates that the hydrogen has been completely pumped out. The third pumping pump (10) is turned off to pump out the hydrogen. At the same time, silicon tetrachloride accumulates at the bottom of the first recovery chamber (81) after liquefaction. As more and more liquid silicon tetrachloride is added, the liquid surface formed by silicon tetrachloride causes the top plate (85) to move upward. When the top plate (85) rises to the limit position along the positioning rod (84), the protruding apex (852) on the top plate (85) just contacts the contact limiter (862) below the limit block (86). At this time, the contact limiter (862) sends a signal to the fifth electromagnetic control valve (812). The fifth electromagnetic control valve (812) opens, allowing the liquid silicon tetrachloride to flow into the liquid accumulation tank (813). The fourth electromagnetic control valve (11) is opened, and the third pumping pump (10) is started to extract the stored argon through the first argon extraction pipe (101) for recycling.

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