A low-resistance polycrystalline silicon carbide bulk body and a preparation method and device thereof

Abstract

This application provides a low-resistivity polycrystalline silicon carbide bulk material and its preparation method and apparatus. The method involves using isostatically pressed graphite as a substrate, first loading it into a reaction mechanism and creating a sealed negative pressure environment through vacuum. Then, the furnace body is heated in sections to a set deposition temperature. Subsequently, argon, hydrogen, methyltrichlorosilane, and nitrogen are sequentially introduced to achieve the set pressure within the furnace, and deposition is carried out at this temperature to obtain a silicon carbide deposit. Finally, the gas supply is stopped, the gas inside the furnace is replaced with nitrogen, and the product is removed after controlled cooling to room temperature. Through vacuum sealing, sectioned temperature control, precise gas supply, and stable pressure deposition, the uniform distribution of reaction gases and the full progress of the reaction are effectively ensured, significantly improving the density, thickness uniformity, and compositional stability of the silicon carbide deposit. Simultaneously, stable nitrogen doping is achieved, resulting in a low-resistivity, high-purity, crack-free, and defect-free polycrystalline silicon carbide bulk material. The process offers strong controllability and good product consistency, meeting the stringent application requirements of high-end industrial fields.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a low-resistivity polycrystalline silicon carbide bulk material and its preparation method and apparatus. Background Technology

[0002] Chemical vapor deposition (CVD) is a process in which gaseous precursors undergo a chemical reaction on the surface of a substrate at high temperatures to generate solid deposits. High-temperature CVD furnaces are required in the production of silicon carbide. A high-temperature CVD furnace is a high-temperature reaction device used for material synthesis. By providing thermal and chemical energy to the reaction gases, the gases react in the furnace and deposit onto the substrate to form the desired material.

[0003] Traditional CVD equipment has a simple air intake structure, which leads to uneven distribution of production gas inside the chamber, resulting in poor consistency in the thickness of the silicon carbide deposition layer. Summary of the Invention

[0004] The technical problem to be solved by this application is that the traditional CVD equipment has a single air intake structure, which leads to uneven distribution of production gas in the cavity and poor consistency of silicon carbide deposition layer thickness.

[0005] In order to solve the above problems, or at least partially solve the above technical problems, this application provides a low-resistivity polycrystalline silicon carbide bulk material and its preparation method and apparatus.

[0006] In a first aspect, the present invention discloses a low-resistivity polycrystalline silicon carbide bulk preparation apparatus, which includes a gas source mechanism, a reaction mechanism, and a tail gas filtration mechanism, wherein the gas source mechanism is connected to the reaction mechanism, and the reaction mechanism is connected to the tail gas filtration mechanism. The gas source mechanism inputs reaction gas into the reaction mechanism, and silicon carbide is prepared by chemical vapor deposition in the reaction mechanism. The gas in the reaction mechanism is discharged to the tail gas filtration mechanism, and the tail gas filtration mechanism filters the gas and discharges it to the outside. Deposits are prepared in the reaction mechanism. The reaction mechanism includes an outer shell, an inner shell, an inlet gas stratification assembly, and an outlet gas stratification assembly. The outer shell and the inner shell are connected, and a cavity is provided between the outer shell and the inner shell. The outer shell is provided with a first air inlet and a first air outlet, and the inner shell is provided with a second air inlet and a second air outlet. The positions of the first air inlet and the second air inlet are matched, and the positions of the first air outlet and the second air outlet are matched. An air inlet stratification component is provided between the first air inlet and the second air inlet, and an air outlet stratification component is provided between the first air outlet and the second air outlet.

[0007] Preferably, in the device according to claim 1, the inner shell includes an air inlet channel and an air outlet channel, the air inlet channel being disposed at the second air inlet and the air outlet channel being disposed at the second air outlet.

[0008] Preferably, the air intake stratification assembly includes a flow equalization plate and a cover. The flow equalization plate is disposed inside the cover and is located on the air intake side near the air intake channel. The opening of the cover is placed on the air intake channel.

[0009] Preferably, the air stratification assembly includes a stratified guide plate, which is disposed on the air outlet side near the air outlet channel.

[0010] Secondly, the present invention discloses a low-resistivity polycrystalline silicon carbide bulk material, which is manufactured by the aforementioned low-resistivity polycrystalline silicon carbide bulk material preparation apparatus.

[0011] Thirdly, this invention discloses a method for preparing low-resistivity polycrystalline silicon carbide bulk material, applicable to an apparatus for preparing low-resistivity polycrystalline silicon carbide bulk material, comprising, Obtain isostatic graphite, place it into the reaction mechanism, evacuate the reaction mechanism to form a negative pressure sealed environment, and heat the reaction mechanism to the first temperature value. Argon, hydrogen, methyltrichlorosilane, and nitrogen are successively introduced into the reaction mechanism at preset flow rates until the pressure inside the reaction mechanism reaches a preset first pressure value. Deposition takes place for a preset first time period to obtain the sediment. Stop the gas feed, introduce nitrogen into the reaction unit to purge the gas, lower the temperature inside the reaction unit to room temperature, and remove the deposit.

[0012] Preferably, isostatically pressed graphite is obtained, placed inside a reaction apparatus, and a vacuum is applied to the reaction apparatus to create a negative pressure sealed environment. The reaction apparatus is then heated to a first temperature value. Specifically, this includes the following steps: To obtain isostatically pressed graphite, a vacuum process is performed inside the reaction mechanism to create a negative pressure sealed environment. During the second preset time period, the temperature inside the reaction apparatus is raised from room temperature to 600°C, and then kept at 600°C for the third preset time period. During the preset fourth time period, the temperature inside the reaction device is raised from 600℃ to the preset first temperature value and kept at that temperature for 2 hours.

[0013] Preferably, the gas feed is stopped, nitrogen is introduced into the reaction unit to purge the gas, the temperature inside the reaction unit is reduced to room temperature, and the deposit is removed. Specifically, this includes the following steps: Stop feeding gas and heating into the reaction mechanism, and evacuate the reaction mechanism to negative pressure. The temperature of the reaction mechanism will drop from the preset first temperature value to 800°C within 4 hours. Nitrogen gas is continuously introduced into the reaction mechanism to maintain a positive pressure, and the reaction mechanism is allowed to cool naturally to room temperature. Nitrogen gas is introduced into the reaction mechanism to replace the internal gas, and the reaction mechanism is restored to atmospheric pressure. The deposits are then removed from the reaction mechanism.

[0014] Preferably, the first temperature value is 1300-1400℃, the first time period is 1-2 hours, the second time period is 1.5-2 hours, the third time period is 1-2 hours, the fourth time period is 2-4 hours, and the first pressure value is 18000-20000Pa.

[0015] Preferably, the flow rates of argon, hydrogen, methyltrichlorosilane, and nitrogen are 90–120 L / min, 180–240 L / min, 60–100 g / min, and 15–50 L / min, respectively.

[0016] The technical solution provided in this application has the following advantages compared with the prior art: This application provides a low-resistivity polycrystalline silicon carbide bulk material and its preparation method and apparatus. The preparation method involves using isostatically pressed graphite as a substrate, first loading it into a reaction mechanism and creating a sealed negative pressure environment through vacuum. Then, the furnace body is heated in sections to a set deposition temperature. Subsequently, argon, hydrogen, methyltrichlorosilane, and nitrogen are sequentially introduced to achieve the set pressure within the furnace, and deposition is carried out at this temperature to obtain a silicon carbide deposit. Finally, the gas supply is stopped, the gas inside the furnace is replaced with nitrogen, and the product is removed after controlled cooling to room temperature. Through vacuum sealing, sectioned temperature control, precise gas supply, and stable pressure deposition, the uniform distribution of reaction gases and the full progress of the reaction are effectively ensured, significantly improving the density, thickness uniformity, and compositional stability of the silicon carbide deposit. Simultaneously, stable nitrogen doping is achieved, resulting in a low-resistivity, high-purity, crack-free, and defect-free polycrystalline silicon carbide bulk material. The process offers strong controllability and good product consistency, meeting the stringent application requirements of high-end industrial fields.

[0017] A low-resistivity polycrystalline silicon carbide bulk material is disclosed. This bulk material is prepared using the aforementioned low-resistivity polycrystalline silicon carbide bulk material preparation method, relying on a stable deposition process and precise parameter control to form the target microstructure and properties. The silicon carbide bulk material prepared by this method has the characteristics of low resistivity, high purity, high density, uniform thickness, and stable performance. It also has good thermal conductivity, wear resistance, and corrosion resistance, which can meet the application requirements of high-end fields such as semiconductor equipment, new energy, and aerospace.

[0018] The fabrication apparatus mainly includes a gas source mechanism, a reaction mechanism, and a tail gas filtration mechanism. The reaction mechanism adopts a double-layer structure with an outer shell and an inner shell. A gas inlet stratification assembly, consisting of a flow equalization plate and a cover, is installed between corresponding gas inlets, and a stratified flow guide plate is installed between corresponding gas outlets. It is also equipped with inlet and outlet channels to achieve uniform gas intake and orderly gas exhaust. This apparatus achieves uniform gas distribution through the gas inlet stratification assembly, solving the problem of uneven gas intake in traditional apparatuses and improving deposition consistency. Combined with the outlet stratification assembly to stabilize the flow field and pressure, and integrated with a temperature control and vacuum system, it provides a stable and reliable reaction environment for silicon carbide deposition, ensuring bulk quality and production stability. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart of the steps for preparing a low-resistivity polycrystalline silicon carbide bulk material is provided in this application; Figure 2 A detailed flowchart of step S1 in a method for preparing a low-resistivity polycrystalline silicon carbide bulk material provided in this application; Figure 3 A detailed flowchart of step S3 in a method for preparing a low-resistivity polycrystalline silicon carbide bulk material provided in this application; Figure 4 This application provides a schematic diagram of the structure of a low-resistivity polycrystalline silicon carbide bulk material. Figure 5 A surface electron microscope scan image of a low-resistivity polycrystalline silicon carbide bulk material provided in this application; Figure 6 A bottom electron microscope scan image of a low-resistivity polycrystalline silicon carbide bulk material provided for this application; Figure 7 A scanning electron microscope image of the middle part of a low-resistivity polycrystalline silicon carbide bulk material provided in this application; Figure 8 A schematic diagram of a low-resistivity polycrystalline silicon carbide bulk preparation apparatus provided in this application; Figure 9 A schematic diagram of the reaction mechanism of a low-resistivity polycrystalline silicon carbide bulk preparation apparatus provided in this application; Figure 10 This is a cross-sectional view of the reaction mechanism of a low-resistivity polycrystalline silicon carbide bulk preparation apparatus provided in this application.

[0022] Explanation of reference numerals in the attached figures: 1. Low-resistivity polycrystalline silicon carbide bulk material preparation device; 11. Gas supply system; 12. Reaction mechanism; 121. Outer casing; 1211. First air inlet; 1212. First air outlet; 122. Inner shell; 1221. Second air inlet; 1222. Second air outlet; 1223. Graphite material platform; 1224. Air inlet channel; 1225. Air outlet channel; 123. Air intake stratification assembly; 1231. Air distribution plate; 1232. Cover; 124. Air stratification assembly; 125. Heating element; 126. Airway; 127. Vent pipe; 128. Sealed door; 13. Exhaust gas filtration system. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] Firstly, see Figures 1-3 This invention discloses a method for preparing low-resistivity polycrystalline silicon carbide bulk material, comprising, Step S1: Obtain isostatic graphite, place it into the reaction mechanism, evacuate the reaction mechanism to form a negative pressure sealed environment, and heat the reaction mechanism to the first temperature value. Step S2: Argon, hydrogen, methyltrichlorosilane and nitrogen are successively introduced into the reaction mechanism at preset flow rates until the pressure inside the reaction mechanism reaches a preset first pressure value, and the material is deposited for a preset first time period to obtain the deposit. Step S3: Stop the gas feed, introduce nitrogen into the reaction unit to purge the gas, reduce the temperature inside the reaction unit to room temperature, and remove the deposit.

[0025] Specifically, in step S1, the isostatically pressed graphite substrate is first placed into the reaction mechanism, and the furnace body is evacuated to create a sealed negative pressure environment. Then, the furnace temperature is steadily heated to the set first temperature value through staged heating, providing a stable, clean, and impurity-free high-temperature reaction environment for subsequent deposition. This effectively removes air, moisture, and impurity gases from the furnace, preventing the substrate and gases from being oxidized at high temperatures. At the same time, the steady heating ensures a uniform and stable temperature field within the furnace, eliminating thermal stress and preventing defects such as cracking and deformation during subsequent deposition.

[0026] Specifically, in step S2, argon, hydrogen, methyltrichlorosilane (MTS), and nitrogen are sequentially introduced into the reaction apparatus according to a preset order and flow rate. The gas inlet flow rate is adjusted to bring the furnace pressure to a preset first pressure value. This is maintained at a constant temperature and pressure for a preset duration to complete the chemical vapor deposition reaction and generate silicon carbide deposits. By precisely controlling the gas inlet sequence, flow rate ratio, and furnace pressure, the reaction gases are fully mixed, uniformly distributed, and the reaction is stabilized, achieving uniform nitrogen doping and ensuring high density, uniform composition, and stable and controllable resistivity of the deposits. The MTS is heated in an MTS evaporator, which needs to be heated to 85°C to convert the MTS from a liquid to a gaseous state before it is introduced into the reaction apparatus.

[0027] Specifically, in step S3, after deposition is completed, the reaction gas supply is stopped, nitrogen is introduced into the furnace to replace the residual reaction tail gas, and the furnace temperature is controlled to steadily decrease to room temperature. After the gas in the furnace is completely replaced and the pressure returns to normal, the obtained silicon carbide block is taken out. This process can safely remove harmful tail gas, avoid oxidation and pollution, and eliminate residual thermal stress inside the deposited block by slow cooling, ensuring that the product is crack-free and deformation-free, ultimately obtaining a complete, stable, and qualified low-resistivity polycrystalline silicon carbide block.

[0028] Specifically, using isostatically pressed graphite as the substrate, it is first placed into the reaction mechanism and a vacuum is drawn to create a sealed negative pressure environment. Then, the furnace body is heated in sections to the set deposition temperature. Subsequently, argon, hydrogen, methyltrichlorosilane, and nitrogen are introduced in sequence to bring the furnace pressure to the set value and maintain the temperature for deposition, resulting in silicon carbide deposits. Finally, the gas supply is stopped, the gas inside the furnace is replaced with nitrogen, and the product is removed after controlled cooling to room temperature. Through vacuum sealing, segmented temperature control, precise gas supply, and stable pressure deposition, the uniform distribution of reaction gases and the full progress of the reaction are effectively ensured, significantly improving the density, thickness uniformity, and compositional stability of the silicon carbide deposited layer. At the same time, stable nitrogen doping is achieved, resulting in polycrystalline silicon carbide blocks with low resistivity, high purity, no cracks, and no obvious defects. The process has strong controllability and good product consistency, which can meet the stringent application requirements of high-end industrial fields.

[0029] Furthermore, this invention employs chemical vapor deposition, using MTS as the reactant gas, through... carrier gas To protect the substrate, nitrogen is doped during the deposition process to grow bulk SiC on isostatically pressed graphite at specific temperatures and pressures. The reaction formula is as follows: .

[0030] in, In this method, the dilution gas and carrier gas not only act as catalysts during the reaction, but also influence the reaction rate and the formation of bulk material.

[0031] Step S1 specifically includes the following steps: Step S11: Obtain isostatic graphite and evacuate the reaction mechanism to form a negative pressure sealed environment; Step S12: During the preset second time period, the temperature inside the reaction device is raised from room temperature to 600°C, and then kept at 600°C for the preset third time period. Step S13: During the preset fourth time period, the temperature inside the reaction device is raised from 600℃ to the preset first temperature value and kept at that temperature for 2 hours.

[0032] Specifically, isostatically pressed graphite is first obtained and placed into the reaction apparatus. The reaction apparatus is then evacuated to create a negative pressure sealed environment for 15-30 minutes, until the pressure drops below 100 Pa. The vacuum pump is then shut off. After one hour, the real-time pressure value is monitored. If the pressure rise is ≤600 Pa, production can continue; if it exceeds 600 Pa, production is stopped, and the apparatus is leak-checked. Subsequently, within a preset second time period, the furnace temperature is steadily increased from room temperature to 600℃ and held at this temperature for a preset third time period. Finally, within a preset fourth time period, the furnace temperature is increased from 600℃ to a preset first temperature value and held for 2 hours, completing the pretreatment and temperature preparation before deposition. Step S1 creates a clean negative pressure environment by vacuuming, effectively removing air, moisture, and impurity gases from the furnace and preventing impurities from interfering with subsequent deposition reactions. The segmented heating and stepped heat preservation design can stably establish a uniform temperature field, reduce thermal stress caused by sudden temperature changes, and at the same time, heat preservation at 600℃ can further remove residual moisture and impurities on the substrate surface, providing a stable, clean, and temperature-uniform reaction basis for subsequent chemical vapor deposition and ensuring deposition quality.

[0033] Step S3 specifically includes the following steps: Step S31: Stop feeding gas and heating into the reaction mechanism, evacuate the reaction mechanism to negative pressure, and cool the reaction mechanism at a constant rate from the preset first temperature value to 800°C within 4 hours. Step S32: Continuously introduce nitrogen gas into the reaction mechanism to maintain a positive pressure inside the reaction mechanism, and allow the reaction mechanism to cool naturally to room temperature; Step S33: Nitrogen gas is introduced into the reaction mechanism to replace the internal gas, the reaction mechanism returns to atmospheric pressure, and the deposit is removed from the reaction mechanism.

[0034] Specifically, the gas supply and heating of the reaction mechanism are first stopped, the furnace is evacuated to a negative pressure state, and the furnace temperature is controlled to drop uniformly from the deposition temperature to 800°C within 4 hours. Then, nitrogen is continuously introduced into the furnace while maintaining positive pressure, allowing the furnace to cool naturally to room temperature. Finally, nitrogen is introduced again to replace the residual gas in the furnace. After the pressure returns to atmospheric pressure, the obtained silicon carbide deposit is removed. Step S3, by first evacuating and then cooling uniformly, can quickly remove residual reaction gases and avoid internal stress cracking of the product due to a sudden drop in temperature; cooling under nitrogen positive pressure can effectively prevent high-temperature oxidation of the deposit, ensuring material purity and performance stability; finally, nitrogen replacement ensures the safety of the opening operation and avoids impurity contamination, resulting in a complete, defect-free, and stable silicon carbide block.

[0035] The first temperature value is 1300~1400℃, the first time period is 1~2 hours, the second time period is 1.5~2 hours, the third time period is 1~2 hours, the fourth time period is 2~4 hours, and the first pressure value is 18000~20000Pa.

[0036] The flow rates of argon, hydrogen, methyltrichlorosilane, and nitrogen were 90–120 L / min, 180–240 L / min, 60–100 g / min, and 15–50 L / min, respectively.

[0037] The MTS used in this invention has a purity of 6N. It is understood that the purity of the raw materials directly affects the purity of the bulk material; the higher the purity, the fewer impurities volatilize during the reaction process, and the fewer byproducts are produced by deposition.

[0038] Example 1: Step S1: Clean the furnace chamber and place the isostatic graphite on the graphite material platform fixture. Close the sealing door and evacuate the furnace chamber for 15-30 minutes until the pressure is below 100 Pa. After the pressure rise rate is ≤600 Pa, continue heating according to the program. Within 1.5 hours, the room temperature is uniformly raised to 600℃ and held for 1 hour. Then, within 2 hours, the temperature in the reaction mechanism is uniformly raised to 1350℃ and held for 2 hours to complete the preparation before deposition. Step S2: Start the MTS heating system to vaporize it, and sequentially introduce argon gas at 90 L / min, hydrogen gas at 180 L / min, MTS gas at 60 g / min, and nitrogen gas at 15 L / min into the reaction mechanism. Stably control the pressure in the deposition chamber of the reaction mechanism at 18000–20000 Pa, and deposit at a constant temperature of 1350℃ for 120 h to obtain silicon carbide deposits. Step S3: After deposition, stop the gas supply and heating, evacuate to below 100 Pa, and uniformly reduce the temperature from 1350℃ to 800℃ within 4 hours. When the temperature is below 600℃, introduce nitrogen to maintain a slight positive pressure, allow it to cool naturally to room temperature, introduce nitrogen into the reaction mechanism, replace the nitrogen three times, restore normal pressure, remove the deposit, and obtain a low-resistivity polycrystalline silicon carbide block.

[0039] Example 2: Step S1: Clean the furnace chamber and place the isostatic graphite on the graphite material platform fixture. Close the sealing door and evacuate the furnace chamber for 15-30 minutes until the pressure is below 100 Pa. After the pressure rise rate is ≤600 Pa, continue heating according to the program. Within 1.5 hours, the room temperature is uniformly raised to 600℃ and held for 1 hour. Then, within 2 hours, the temperature in the reaction mechanism is uniformly raised to 1300℃ and held for 2 hours to complete the preparation before deposition. Step S2: Start the MTS heating system to vaporize it, and sequentially introduce argon gas at 120 L / min, hydrogen gas at 240 L / min, MTS gas at 100 g / min and nitrogen gas at 25 L / min into the reaction mechanism. Stabilize the pressure in the deposition chamber of the reaction mechanism at 18000–20000 Pa, and deposit at a constant temperature of 1300℃ for 100 h to obtain silicon carbide deposits. Step S3: After deposition, stop the gas supply and heating, evacuate to below 100 Pa, and uniformly reduce the temperature from 1300℃ to 800℃ within 4 hours. When the temperature is below 600℃, introduce nitrogen to maintain a slight positive pressure, allow it to cool naturally to room temperature, introduce nitrogen into the reaction mechanism, replace the nitrogen three times, restore normal pressure, remove the deposit, and obtain a low-resistivity polycrystalline silicon carbide block.

[0040] Example 3: Step S1: Clean the furnace chamber and place the isostatic graphite on the graphite material platform fixture. Close the sealing door and evacuate the furnace chamber for 15-30 minutes until the pressure is below 100 Pa. After the pressure rise rate is ≤600 Pa, continue heating according to the program. Within 1.5 hours, the room temperature is uniformly raised to 600℃ and held for 1 hour. Then, within 3 hours, the temperature in the reaction mechanism is uniformly raised to 1400℃ and held for 2 hours to complete the preparation before deposition. Step S2: Start the MTS heating system to vaporize it, and sequentially introduce argon gas at 90 L / min, hydrogen gas at 180 L / min, MTS gas at 60 g / min and nitrogen gas at 15 L / min into the reaction mechanism. Stably control the pressure in the deposition chamber of the reaction mechanism at 18000–20000 Pa, and deposit at a constant temperature of 1400℃ for 120 h to obtain silicon carbide deposits. Step S3: After deposition, stop the gas supply and heating, evacuate to below 100 Pa, and uniformly reduce the temperature from 1400℃ to 800℃ within 4 hours. When the temperature is below 600℃, introduce nitrogen to maintain a slight positive pressure, allow it to cool naturally to room temperature, introduce nitrogen into the reaction mechanism, replace the nitrogen three times, restore normal pressure, remove the deposit, and obtain a low-resistivity polycrystalline silicon carbide block.

[0041] According to GB / T 17473.3-2008 standard, the volume resistivity of the samples was tested, and the results are shown in Table 1. Table 2 shows the thermal conductivity system of a low-resistivity polycrystalline silicon carbide bulk material prepared according to the low-resistivity polycrystalline silicon carbide bulk material preparation method, measured by the flash method according to GB / T 22588-2008.

[0042] Table 1: Resistivity test results mentioned in Examples 1-3

[0043] Table 2: Thermal conductivity results

[0044] Secondly, see Figures 4-7 The present invention discloses a low-resistivity polycrystalline silicon carbide bulk material, which is prepared by the low-resistivity polycrystalline silicon carbide bulk material preparation method disclosed in the first aspect.

[0045] Specifically, the invention discloses a low-resistivity polycrystalline silicon carbide bulk material, prepared using the aforementioned method for preparing low-resistivity polycrystalline silicon carbide bulk materials. This method relies on a stable deposition process and precise parameter control to form the target microstructure and properties. The silicon carbide bulk material obtained by this method possesses characteristics of low resistivity, high purity, high density, uniform thickness, and stable performance. It also exhibits good thermal conductivity, wear resistance, and corrosion resistance, meeting the requirements of high-end fields such as semiconductor equipment, new energy, and aerospace. Furthermore, the low-resistivity polycrystalline silicon carbide bulk material obtained by this invention is mainly applied in fields requiring excellent thermal conductivity, wear resistance, corrosion resistance, and electrical conductivity, such as semiconductor manufacturing equipment consumables, new energy and power electronics, aerospace and high-temperature systems, nuclear energy and extreme environments, and optoelectronics and sensing fields. With the upgrading of industries such as semiconductors and new energy, the demand for the low-resistivity polycrystalline silicon carbide bulk material obtained by this invention will continue to grow, making it irreplaceable in high-end industrial fields.

[0046] Thirdly, see Figures 8-10This invention discloses a low-resistivity polycrystalline silicon carbide bulk material preparation apparatus 1, which includes a gas source mechanism 11, a reaction mechanism 12, and a tail gas filtration mechanism 13. The gas source mechanism 11 is connected to the reaction mechanism 12, and the reaction mechanism 12 is connected to the tail gas filtration mechanism 13. The gas source mechanism 11 inputs reaction gas into the reaction mechanism 12, where silicon carbide is prepared by chemical vapor deposition. The gas in the reaction mechanism 12 is discharged to the tail gas filtration mechanism 13, where it is filtered before being discharged to the outside. A deposit is prepared within the reaction mechanism 12. Specifically, the gas source mechanism 11 supplies reaction gas to the reaction mechanism 12, where silicon carbide chemical vapor deposition is completed. The tail gas after the reaction is purified by the tail gas filtration mechanism 13 before being discharged.

[0047] The reaction mechanism 12 includes an outer shell 121, an inner shell 122, an inlet gas stratification component 123, and an outlet gas stratification component 124. The outer shell 121 is connected to the inner shell 122, and a cavity is provided between the outer shell 121 and the inner shell 122. The outer shell 121 is provided with a first inlet 1211 and a first outlet 1212, and the inner shell 122 is provided with a second inlet 1221 and a second outlet 1222. The positions of the first inlet 1211 and the second inlet 1221 are matched, and the positions of the first outlet 1212 and the second outlet 1222 are matched. The inlet gas stratification component 123 is located between the first inlet 1211 and the second inlet 1221, and the outlet gas stratification component 124 is located between the first outlet 1212 and the second outlet 1222. The inner shell 122 is provided with a graphite material stage 1223, and the reaction stage is located above the outlet channel 1225.

[0048] Specifically, the inner shell 122 of the reaction mechanism 12 is equipped with a graphite stage 1223, on which corresponding deposits are formed. Isostatic graphite is placed on the graphite stage 1223. The gas source mechanism 11 inputs a mixture of argon, hydrogen, methyltrichlorosilane and nitrogen, wherein the flow rates of the argon, hydrogen, methyltrichlorosilane and nitrogen mixture are 90-120 L / min, 180-240 L / min, 60-100 g / min and 15-50 L / min, respectively. By controlling the temperature value inside the reaction mechanism 12, a low-resistivity polycrystalline silicon carbide bulk material is obtained by chemical vapor deposition on the graphite stage 1223 with isostatic graphite as the substrate through doping. The exhaust gas filtration mechanism 13 filters the mixed gas discharged from the reaction mechanism 12 to meet the emission requirements. The reaction mechanism 12 adopts a double-shell structure with an outer shell 121 and an inner shell 122. The outer shell 121 and the inner shell 122 are respectively provided with air inlets and outlets in matching positions. An air inlet stratification component 123 is set between the air inlets of the outer shell 121 and the inner shell 122, and an air outlet stratification component 124 is set between the air outlets. By adding an air inlet stratification component 123 with a flow equalization plate 1231 in the air inlet path, the core problem of uneven distribution of reaction gas after entering the cavity caused by the single air inlet structure of traditional CVD devices is solved from the root. Multi-level homogenization and uniform gas distribution of reaction gas are realized, which significantly improves the thickness uniformity and composition consistency of silicon carbide deposition layer. The matching air outlet stratification component 124 can realize the smooth and orderly convergence and discharge of exhaust gas, avoiding turbulent flow field and pressure fluctuations in the reaction mechanism 12.

[0049] The reaction mechanism 12 includes a heating element 125, which is connected to the inner shell 122 and installed on the inner wall of the inner shell 122. Specifically, the heating element 125 can heat the interior of the inner shell 122 to create a high-temperature environment for high-temperature deposition.

[0050] As one embodiment, a temperature sensor is provided in the inner shell 122 of the reaction mechanism 12 to sense the internal temperature value and connect to the background control system. The real-time temperature value is transmitted to the background control system. The heating component 125 transmits signals to the background control system. The background control system controls the starting, stopping, and adjustment of the heating component 125 through the signals. The background control system determines whether it is necessary to adjust the temperature by controlling the heating component 125 based on the temperature value collected by the temperature sensor.

[0051] Furthermore, within the reaction mechanism 12, the inlet gas stratification component 123 and the outlet gas stratification component 124, together with the double-layer water-cooling component, the insulation structure and the heating component 125, can maintain a stable temperature field and deposition environment within the cavity, ensuring the preparation quality and batch stability of the low-resistivity polycrystalline silicon carbide bulk. At the same time, the complete exhaust gas filtration chain can achieve compliant purification and emission of exhaust gas. The overall device structure is adapted to the needs of large-scale stable preparation of low-resistivity polycrystalline silicon carbide bulk.

[0052] The inner shell 122 includes an air intake channel 1224 and an air outlet channel 1225. The air intake channel 1224 is located at the second air inlet 1221, and the air outlet channel 1225 is located at the second air outlet 1222. Specifically, the gas input by the gas source mechanism 11 enters the inner shell 122 through the air intake channel 1224, and the gas inside the inner shell 122 needs to be output to the exhaust gas filter mechanism 13 through the air outlet channel 1225 to prevent the gas inside from overflowing from other channels.

[0053] The air intake stratification assembly 123 includes a flow equalization plate 1231 and a cover 1232. The flow equalization plate 1231 is disposed inside the cover 1232 and is located on the air intake side near the air intake channel 1224. The opening of the cover 1232 covers the air intake channel 1224. The air exhaust stratification assembly 124 includes a stratification guide plate and is located on the air exhaust side near the air exhaust channel 1225.

[0054] Specifically, the inlet air stratification assembly 123 consists of a flow equalization plate 1231 and a cover 1232. The flow equalization plate 1231 is installed inside the cover 1232 and close to the inlet side of the inlet channel 1224. The cover 1232 is opened and installed on the inlet channel 1224. The outlet air stratification assembly 124 adopts a layered guide plate, which is arranged on the outlet side of the outlet channel 1225 to achieve a structural combination of inlet air homogenization and outlet air guidance. The combination of the cover 1232 and the flow equalization plate 1231 makes the gas entering the cavity evenly dispersed, solving the problem of uneven distribution caused by traditional single inlet air. At the same time, the layered guide plate smoothly discharges the exhaust gas, making the flow field in the cavity more stable and the pressure and temperature field more uniform, significantly improving the thickness consistency of the silicon carbide deposition layer and the product quality.

[0055] The reaction mechanism 12 includes an inlet pipe 126 and an outlet pipe 127. The inlet pipe 126 is inserted into the outer shell 121 and the inner shell 122, and the outlet pipe 127 is also inserted into the outer shell 121 and the inner shell 122. The inlet pipe 126 is connected to the air source mechanism 11, and the outlet pipe 127 is connected to the exhaust gas filtration mechanism 13. Furthermore, the outlet pipe 127 is connected to an air extraction mechanism, which extracts air from the reaction mechanism 12 through the outlet pipe 127, thereby creating a negative pressure space within the reaction mechanism 12.

[0056] Specifically, the reaction mechanism 12 is equipped with an inlet pipe 126 and an outlet pipe 127. Both pipes pass through the outer shell 121 and the inner shell 122. The inlet pipe 126 is connected to the gas source mechanism 11 for inputting process gas. The outlet pipe 127 is connected to the tail gas filtration mechanism 13 and the extraction mechanism, respectively. The extraction mechanism can extract air from the inside of the reaction mechanism 12 through the outlet pipe 127 to create a negative pressure environment in the cavity. This achieves the integration and sharing of three channels: gas inlet, vacuum extraction, and exhaust. The structure is simple and compact, and the sealing is reliable. It can stably deliver reaction gas, quickly establish and maintain negative pressure in the cavity to ensure that the vacuum degree meets the standard before deposition, and smoothly discharge tail gas, thereby improving the operational stability of the device and the controllability of the deposition process.

[0057] As one embodiment, air valves are provided on the air inlet pipe 126 and the air outlet pipe 127. By closing the air valves, a sealed space is formed inside the reaction mechanism 12. When pressurization or depressurization is required, the air valves can be opened to achieve the operation. In this embodiment, the air valves are solenoid valves and are connected to the background control system. The background control system controls the air valves to start, close, and adjust via signals.

[0058] As one embodiment, the inner shell 122 of the reaction mechanism 12 is equipped with a pressure sensor, which can detect the pressure value inside the inner shell 122. The pressure sensor is connected to the background control system and transmits the real-time collected pressure value to the background control system. Then, the system controls the start, stop, and adjustment of the air valve through the signal.

[0059] The outer shell 121 is equipped with a double-layer water-cooling assembly, and the inner shell 122 is equipped with a thermal insulation structure. Specifically, the double-layer water-cooling assembly is a double-layer jacketed annular water-cooling cavity. The shell is made of stainless steel and forms a closed cooling water channel inside. The double-layer water-cooling assembly is used to isolate the high temperature inside the cavity, reduce the temperature of the outer wall, and stabilize the internal temperature field, ensuring that the device can operate safely and stably for a long time under high temperature deposition conditions. The thermal insulation structure can prevent the internal temperature from leaking out, thereby reducing heat loss inside the cavity, stabilizing the deposition temperature field, improving temperature control accuracy, and reducing the heat dissipation load of the double-layer water-cooling structure.

[0060] Optionally, the insulation structure of the inner shell 122 is a multi-layered high-purity graphite soft felt layer, a graphite hard felt layer, or carbon... At least one of the following: carbon composite insulation cylinders.

[0061] Optionally, pipes can be installed inside the double-layer water-cooled assembly for transporting refrigerant.

[0062] The reaction mechanism 12 includes a sealing door 128, which is connected to the outer shell 121 and the inner shell 122 respectively. Isostatic graphite can be placed into the graphite material platform 1223 inside the reaction mechanism 12 through the sealing door 128. Closing the sealing door 128 can keep the reaction mechanism 12 in a sealed space and communicate with the outside through the air inlet pipe 126 and the air outlet pipe 127.

[0063] As one embodiment, the outer shell 121 and inner shell 122 of the reaction mechanism 12 are respectively provided with covers, and the outer shell 121 and inner shell 122 are provided with openings. The covers are fastened to the openings on the outer shell 121 and inner shell 122 by a fixing structure, so that a sealed space is formed inside the reaction mechanism 12.

[0064] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0065] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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.

[0066] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, "" means two or more, unless otherwise explicitly specified.

[0067] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0068] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one embodiment or example. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0070] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0071] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for preparing low-resistivity polycrystalline silicon carbide bulk, characterized in that, It includes a gas source mechanism, a reaction mechanism, and an exhaust gas filtration mechanism. The gas source mechanism is connected to the reaction mechanism, and the reaction mechanism is connected to the exhaust gas filtration mechanism. The gas source mechanism inputs reaction gas into the reaction mechanism, and silicon carbide is prepared by chemical vapor deposition in the reaction mechanism. The gas in the reaction mechanism is discharged to the tail gas filtration mechanism, and the tail gas filtration mechanism filters the gas and discharges it to the outside. Deposits are prepared in the reaction mechanism. The reaction mechanism includes an outer shell, an inner shell, an inlet gas stratification assembly, and an outlet gas stratification assembly. The outer shell and the inner shell are connected, and a cavity is provided between the outer shell and the inner shell. The outer shell is provided with a first air inlet and a first air outlet, and the inner shell is provided with a second air inlet and a second air outlet. The positions of the first air inlet and the second air inlet are matched, and the positions of the first air outlet and the second air outlet are matched. An air inlet stratification component is provided between the first air inlet and the second air inlet, and an air outlet stratification component is provided between the first air outlet and the second air outlet.

2. The apparatus according to claim 7, characterized in that, The device according to claim 1 is characterized in that the inner shell includes an air inlet channel and an air outlet channel, the air inlet channel is disposed at the second air inlet, and the air outlet channel is disposed at the second air outlet.

3. The apparatus according to claim 1, characterized in that, The air intake stratification assembly includes a flow equalization plate and a cover. The flow equalization plate is installed inside the cover and is located on the air intake side near the air intake channel. The opening of the cover is placed on the air intake channel.

4. The apparatus according to claim 1, characterized in that, The air stratification assembly includes a stratified baffle, which is positioned on the air outlet side near the air outlet channel.

5. A low-resistivity polycrystalline silicon carbide bulk material, characterized in that, It is manufactured by the low-resistivity polycrystalline silicon carbide bulk preparation apparatus according to any one of claims 1-4.

6. A method for preparing low-resistivity polycrystalline silicon carbide bulk material, characterized in that, The apparatus for preparing low-resistivity polycrystalline silicon carbide bulk material according to any one of claims 1-4 includes, Obtain isostatic graphite, place it into the reaction mechanism, evacuate the reaction mechanism to form a negative pressure sealed environment, and heat the reaction mechanism to the first temperature value. Argon, hydrogen, methyltrichlorosilane, and nitrogen are successively introduced into the reaction mechanism at preset flow rates until the pressure inside the reaction mechanism reaches a preset first pressure value. Deposition takes place for a preset first time period to obtain the sediment. Stop the gas feed, introduce nitrogen into the reaction unit to purge the gas, lower the temperature inside the reaction unit to room temperature, and remove the deposit.

7. The method according to claim 6, characterized in that, Obtain isostatically pressed graphite, place it into a reaction apparatus, evacuate the reaction apparatus to create a negative pressure sealed environment, and heat the reaction apparatus to a first temperature value. The specific steps include: To obtain isostatically pressed graphite, a vacuum process is performed inside the reaction mechanism to create a negative pressure sealed environment. During the second preset time period, the temperature inside the reaction apparatus is raised from room temperature to 600°C, and then kept at 600°C for the third preset time period. During the preset fourth time period, the temperature inside the reaction device is raised from 600℃ to the preset first temperature value and kept at that temperature for 2 hours.

8. The method according to claim 6, characterized in that, Stop the gas feed, introduce nitrogen into the reaction unit to purge the gas, lower the temperature inside the reaction unit to room temperature, and remove the deposits. (Specific details...) Includes the following steps: Stop feeding gas and heating into the reaction mechanism, and evacuate the reaction mechanism to negative pressure. The temperature of the reaction mechanism will drop from the preset first temperature value to 800°C within 4 hours. Nitrogen gas is continuously introduced into the reaction mechanism to maintain a positive pressure, and the reaction mechanism is allowed to cool naturally to room temperature. Nitrogen gas is introduced into the reaction mechanism to replace the internal gas, and the reaction mechanism is restored to atmospheric pressure. The deposits are then removed from the reaction mechanism.

9. The method according to claim 6, characterized in that, The first temperature value is 1300~1400℃, the first time period is 1~2 hours, the second time period is 1.5~2 hours, the third time period is 1~2 hours, the fourth time period is 2~4 hours, and the first pressure value is 18000~20000Pa.

10. The method according to claim 6, characterized in that, The flow rates of argon, hydrogen, methyltrichlorosilane, and nitrogen were 90–120 L / min, 180–240 L / min, 60–100 g / min, and 15–50 L / min, respectively.

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