A purification system and method for high-purity graphite material for semiconductors

Abstract

This invention discloses a purification system and method for high-purity graphite materials for semiconductors, belonging to the field of high-purity graphite material preparation technology. The system includes a high-pressure expansion tank group, intermediate processing and buffer tanks, a vacuum high-temperature furnace, a gas supply system, and a vacuum unit. The method includes: S1, pretreatment and distributed loading; S2, parallel high-pressure expansion processing; S3, discharge and intermediate processing; S4, continuous feeding and high-temperature processing. This invention combines high-pressure expansion physical opening, medium-temperature inert gas purging pre-purification, high-temperature vacuum purification, pulse reaction purification, and high-temperature recasting multi-stage purification technologies, and utilizes a multi-tank parallel and buffer design to achieve semi-continuous production. This system and method can efficiently, with low consumption, and stably prepare semiconductor-grade high-purity graphite materials with an ash content of no more than 2 ppm and a high degree of graphitization, solving the problems of high energy consumption, severe carbon loss, and poor product consistency associated with traditional methods.

Description

Technical Field

[0001] This invention relates to the field of high-purity graphite material preparation technology, and in particular to a purification system and method for producing high-purity, high-graphitization artificial graphite materials required by the semiconductor industry. Background Technology

[0002] Artificial graphite is a key basic material used in the semiconductor industry for the preparation of compound semiconductors such as single-crystal silicon and GaN, and is widely used in components such as high-temperature furnaces, heaters, insulation containers, and epitaxial trays. Semiconductor processes have extremely high requirements for the purity and performance of graphite materials, typically requiring an ash content (i.e., the total content of metallic impurities) of less than 5 ppm, while also requiring a high degree of graphitization to ensure excellent thermal, electrical properties, and mechanical strength. Traditional methods for preparing high-purity graphite mainly employ high-temperature halogen purification (treatment with high-temperature chlorine or Freon). This method suffers from problems such as high temperature, high energy consumption, severe carbon loss, and poor product consistency, and is limited to batch production with restricted capacity. Therefore, finding a way to efficiently, efficiently, stably, and continuously remove various impurities without damaging the graphite structure, while maintaining or even repairing the graphite crystal structure, is of great significance for the preparation of semiconductor-grade high-purity graphite. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a purification system and method for high-purity graphite materials for semiconductors that integrates high-pressure expansion, pulse impurity removal and high-temperature recasting technologies, and achieves semi-continuous production through multi-unit collaboration and intelligent control, thereby possessing high efficiency, high purity and high consistency.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A purification system for high-purity graphite materials for semiconductors includes:

[0006] High-pressure expansion tank group: It consists of at least two high-pressure expansion tanks that are set in parallel and can be operated independently. The bottom outlet of each high-pressure expansion tank is connected to a common main collection pipeline through a high-temperature and high-pressure resistant valve. Each high-pressure expansion tank is equipped with an independent heating system and cooling system.

[0007] Intermediate processing and buffer tank: The inlet is connected to the high-pressure expansion tank group through the main collection pipeline. The tank body is a sealable pressure vessel, equipped with an inert gas purging system, and the effective volume is more than 2.5 times the loading capacity of a single high-pressure expansion tank. It is also equipped with a heating system and a cooling system.

[0008] Vacuum high-temperature furnace: The feed inlet is connected to the outlet of the intermediate processing and buffer tank via a vacuum feed valve;

[0009] Gas supply system: connected to the high-pressure expansion tank group, intermediate processing and buffer tank, and vacuum high-temperature furnace, used to supply working gas to the high-pressure expansion tank group, intermediate processing and buffer tank, and vacuum high-temperature furnace;

[0010] Vacuum unit: Connected to a vacuum high-temperature furnace, used to provide a vacuum environment for the vacuum high-temperature furnace.

[0011] The purification system described above is further characterized in that each high-pressure expansion tank in the high-pressure expansion tank group can withstand a working pressure of not less than 5 MPa.

[0012] The purification system described above is further characterized in that each high-pressure expansion tank in the high-pressure expansion tank group can withstand an operating temperature of not less than 600°C.

[0013] The purification system described above is further characterized in that the cooling system for the intermediate processing and buffer tank adopts a cooling jacket structure.

[0014] The purification system described above is further characterized in that the intermediate processing and buffer tanks are also equipped with level gauges and temperature sensors.

[0015] The purification system described above is further characterized in that the vacuum feed valve is a gate valve with a locking chamber.

[0016] A method for purifying high-purity graphite material for semiconductors, employing the purification system described above, includes the following steps:

[0017] S1. Pre-processing and distributed loading:

[0018] The graphite powder raw material is distributed and loaded into each high-pressure expansion tank in the high-pressure expansion tank group.

[0019] S2, Parallel high-pressure expansion treatment:

[0020] The central control system schedules each high-pressure expansion tank in the high-pressure expansion tank group to start the expansion process in a staggered manner.

[0021] S3. Discharge and intermediate processing:

[0022] After high-pressure expansion, the material enters the intermediate treatment and buffer tank through the main collection pipeline. In the intermediate treatment and buffer tank, inert gas is continuously blown out to purify and homogenize it.

[0023] S4. Continuous feeding and high-temperature treatment:

[0024] The intermediate processing and buffer tanks are fed into the vacuum high-temperature furnace through a vacuum feeding valve. The materials in the furnace undergo high-temperature purification and high-temperature recasting treatment in sequence. After the treatment is completed, the process is controlled to cool the material, and the final high-purity graphite product is obtained after exiting the furnace.

[0025] The purification method described above is further characterized in that, in step S2, the expansion process is as follows: inert gas is introduced to 2-4 MPa, heated to 300-500°C and kept at that temperature for 1-3 hours, and then the pressure is released instantly.

[0026] The purification method described above is further characterized in that, in step S3, the material is continuously purged with inert gas while the temperature is controlled in the intermediate processing and buffer tank for purification and homogenization.

[0027] The purification method described above is further characterized in that the high-temperature treatment in step S4 is divided into three stages:

[0028] The first stage is high-temperature vacuum purification: under vacuum conditions, the temperature is raised to 1800-2200℃ and held to remove volatile impurities;

[0029] The second stage is pulse reaction impurity removal: CF4 / Ar is alternately introduced in a pulsed manner to remove metallic impurities;

[0030] The third stage involves high-temperature recasting: heating to 2500-2800℃ and holding at that temperature to repair the graphitized structure.

[0031] The purification system and method for high-purity graphite materials for semiconductors provided by this invention have the following significant advantages compared with the prior art:

[0032] This invention enables semi-continuous production, significantly improving efficiency and capacity. By coordinating the parallel operation of high-pressure expansion tanks, intermediate processing tanks, and buffer tanks, it breaks through the bottleneck of traditional pure batch production. High-pressure expansion can be performed in parallel, while vacuum high-temperature processing can be continuously fed, resulting in a significant increase in system capacity and high equipment utilization. The system adopts semi-continuous production, increasing overall capacity by approximately 50% or more compared to traditional pure batch high-temperature furnaces.

[0033] This invention features an original multi-stage purification path of "high-pressure expansion - intermediate purification - high-temperature treatment," which boasts high purification efficiency and extremely high product purity. The high-pressure expansion process utilizes the physical force of instantaneous gas depressurization to open the closed pores of graphite, exposing encapsulated impurities and creating the preconditions for subsequent deep impurity removal. This avoids the limitations of relying solely on high-temperature chemical reactions. The intermediate treatment and buffering process, while buffering and homogenizing the material, performs medium-temperature purging for pre-removal of impurities, removing some low-temperature volatile components in advance. This significantly reduces the burden on the downstream vacuum high-temperature furnace, shortens its processing time in the low-temperature section, and improves overall energy efficiency.

[0034] This invention employs a CF4 / Ar pulsed reaction in the pulsed reaction purification and high-temperature recasting stages to efficiently remove metallic impurities while avoiding excessive carbon etching caused by continuous CF4 flow. The final high-temperature recasting not only completely removes trace residual impurities but, more importantly, repairs the graphitized structure, achieving both "ultra-high purity" and "high graphitization degree"—two key indicators. The high-purity graphite material processed by this invention has an ash content not exceeding 2 ppm, and under optimized processes, can reach below 1 ppm. The final product's graphitization degree can reach over 98%, meeting the stringent requirements of the semiconductor industry.

[0035] This invention also features intelligent control, resulting in excellent product consistency. The central control system provides global scheduling and intelligently controls the operation sequence of each unit (such as staggered puffing, intelligent discharge authorization, and pulse air supply) through real-time feedback of signals such as material level and temperature. This ensures the accuracy and stability of process parameters, greatly improving product consistency and reliability. The ash content deviation between different production batches can be controlled within ±0.2ppm, and the deviation of key physical properties (such as thermal conductivity) is <4%, meeting the stringent requirements of semiconductor applications for material performance. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the purification scheme for the high-purity graphite material used in semiconductors according to the present invention.

[0037] Figure 2 This is a schematic diagram of the purification system for high-purity graphite materials for semiconductors according to the present invention.

[0038] The components represented by the labels in the diagram are:

[0039] High-pressure expansion tank group-1; intermediate processing and buffer tank-2; vacuum high-temperature furnace-3; gas supply system-4; vacuum unit-5. Detailed Implementation

[0040] Exemplary embodiments of this disclosure will now be described in more detail.

[0041] Example 1

[0042] This embodiment combines Figure 1 and Figure 2 This invention introduces a purification system for high-purity graphite materials used in semiconductors, the purification system specifically comprising:

[0043] High-pressure expansion tank group 1:

[0044] It consists of at least two parallel, independently operable high-pressure expansion tanks, used for high-pressure expansion of precursor graphite materials.

[0045] The working pressure range of a single high-pressure expansion tank can be set from 0.5 to 5 MPa. Inert gas or reactive gas can be introduced. Each high-pressure expansion tank is equipped with an independent heating system with a working temperature range of 200-600℃. Therefore, the working pressure of a single high-pressure expansion tank in a high-pressure expansion tank group cannot be lower than 5 MPa and the working temperature cannot be lower than 600℃.

[0046] Each high-pressure expansion tank is also equipped with an independent cooling system, and the bottom outlet of each high-pressure expansion tank is connected to a common main collection pipeline through a high-temperature and high-pressure resistant valve.

[0047] Intermediate processing and buffer tank 2:

[0048] The inlet is connected to the high-pressure expansion tank group 1 through the main collection pipeline. The tank body is a sealable pressure vessel equipped with an inert gas purging system. The effective volume is more than 2.5 times the loading capacity of a single high-pressure expansion tank. The inert gas purging system includes a bottom gas distribution plate and a top exhaust port, which are used to maintain an inert positive pressure atmosphere inside the tank and remove volatile substances.

[0049] The primary function of the intermediate processing and buffer tank 2 is to continuously purge the material with inert gas while controlling the temperature, thereby purifying and homogenizing it. Therefore, a heating system is installed to prevent the temperature from dropping too quickly during the inert gas purging process and to raise the temperature to the pre-removal temperature set by the system within a specified time for preheating and removing impurities. This process removes some substances that can be volatilized at low temperatures in advance, reduces the residence time of the next step, the vacuum high-temperature furnace 3, in the low-temperature section, and increases the heating rate of the vacuum high-temperature furnace 3.

[0050] In addition, in some special cases, such as when the high-pressure expansion tank is filled with supercooled material during standby, the intermediate processing and buffer tank 2 will restore the material temperature, which will greatly improve the system efficiency.

[0051] The intermediate processing and buffer tank 2 is also equipped with a cooling system, specifically a cooling jacket structure. This cooling system reduces the material temperature from the pre-removal temperature to the safe operating temperature for vacuum feeding before discharge. Furthermore, the cooling system serves as a guarantee for the operation and safety of the intermediate processing and buffer tank 2, promptly initiating a cooling intervention procedure for the material in any situation requiring accelerated material cooling or temporary cooling during discharge.

[0052] In addition, the tank is equipped with a level gauge and a temperature sensor. The high-precision level gauge is used to monitor the material height in the tank in real time, and the temperature sensor is used to monitor the material temperature.

[0053] Vacuum high-temperature furnace 3:

[0054] Used to provide the high-temperature environment required for purification reaction and recasting process, the feed port is connected to the outlet of intermediate treatment and buffer tank 2 through a vacuum feed valve.

[0055] The vacuum feed valve is a component that smoothly introduces pressurized materials (slightly positive or positive pressure) from the intermediate processing and buffer tank 2 into the vacuum furnace cavity of the vacuum high-temperature furnace 3. This invention employs a gate valve with a locking chamber. This valve has upper and lower gates and a locking chamber with an integrated vacuum assembly in the middle. When the upper gate valve is open, the material falls from the intermediate processing and buffer tank 2 into the locking chamber. After evacuating the locking chamber, the material falls into the high-temperature furnace under gravity, achieving vacuum feeding. Of course, the vacuum feed valve is not limited to the type provided in the embodiments. Furthermore, the vacuum feed valve preferably has a temperature resistance upper limit of not less than 200°C.

[0056] The vacuum high-temperature furnace 3 adopts a double-layer water-cooled jacket structure with a graphite felt composite insulation layer inside. The maximum working temperature can reach 2800℃. The furnace body is equipped with an air inlet, an air outlet, and a temperature measuring port.

[0057] Gas supply system 4:

[0058] Connected to the high-pressure expansion tank group 1, intermediate processing and buffer tank 2, and vacuum high-temperature furnace 3, the gas supply system 4 is used to supply working gas to the high-pressure expansion tank group 1, intermediate processing and buffer tank 2, and vacuum high-temperature furnace 3. The gas supply system 4 includes:

[0059] Inert gas source: high-purity argon (Ar, purity ≥99.999%), equipped with a mass flow controller.

[0060] The reaction gas source is high-purity carbon tetrafluoride (CF4, purity ≥99.999%), equipped with a mass flow controller and a pulse control valve.

[0061] All gas pipelines are made of 316L stainless steel.

[0062] Vacuum Unit 5:

[0063] It is connected to the vacuum high-temperature furnace 3 to provide a vacuum environment for the vacuum high-temperature furnace 3.

[0064] Vacuum unit 5 is connected to the outlet of vacuum high-temperature furnace 3 through a vacuum pipeline. It adopts a system consisting of a Roots pump and a dry screw pump, and the ultimate vacuum degree can reach 5×10-2Pa. It is used to establish and maintain the required vacuum environment inside the furnace and to remove vaporized impurities.

[0065] The system includes an essential central control system under which all components operate. This central control system, employing an industrial computer (or PLC), is electrically connected to the sensors and actuators of each high-pressure expansion tank in high-pressure expansion tank group 1, the level gauges and temperature sensors of intermediate processing and buffer tank 2, and all pumps, valves, and mass flow controllers in the system. It is configured to at least:

[0066] Independently control the working sequence of each high-pressure puffing tank in the high-pressure puffing tank group 1;

[0067] Receive the level (L) and temperature (T) signals of the intermediate treatment and buffer tank 2 in real time;

[0068] According to the preset high-level threshold (L_high) and low-level threshold (L_low), coordinate the discharging sequence of each high-pressure puffing tank in the high-pressure puffing tank group 1. Only when L < L_high, authorize the high-pressure puffing tank that has completed the process to discharge, otherwise list it in the discharging queue to wait;

[0069] Control the heating, purging process and cooling program of the intermediate treatment and buffer tank;

[0070] Overall management of the entire process from puffing to high-temperature treatment.

[0071] Embodiment 2

[0072] On the basis of Embodiment 1, in order to more clearly describe the process and principle of the present invention, this embodiment provides a purification method for high-purity graphite materials for semiconductors, using the purification system introduced in Embodiment 1, including the steps:

[0073] S1. Pretreatment and distributed feeding:

[0074] Distributively load the artificial graphite powder raw material with a particle size of 100 - 500 meshes into each high-pressure puffing tank in the high-pressure puffing tank group 1.

[0075] S2. Parallel high-pressure puffing treatment:

[0076] The central control system schedules each high-pressure puffing tank in the high-pressure puffing tank group 1 to start the puffing program in sequence with a time difference, introduce high-purity argon gas into the high-pressure puffing tank, raise its internal pressure to 2 - 4 MPa, and at the same time raise the temperature to 300 - 500 °C, and keep the pressure and temperature for 1 - 3 hours. Subsequently, quickly release the pressure to atmospheric pressure. During this process, the high-pressure inert gas penetrates into the micropores and interlayers of the graphite particles, and when the pressure is quickly released, the gas rapidly overflows, causing the graphite particles to expand, opening the closed pores, exposing the internal sulfur, nitrogen and other impurities, laying a foundation for subsequent treatment, and at the same time avoiding the oxidation of carbon elements at high temperatures.

[0077] The material after high-pressure puffing is cooled to below 120 °C, preferably below 90 °C, under the action of the cooling system, and is regarded as completing the puffing program.

[0078] S3. Discharging and intermediate treatment:

[0079] In this step, the material after high-pressure puffing treatment enters the intermediate treatment and buffer tank 2 through the aggregate main pipeline, and is continuously purged with inert gas in the intermediate treatment and buffer tank 2 for purification and homogenization, and this process is carried out while controlling the temperature.

[0080] Among them, the discharging process adopts intelligent discharging, including:

[0081] Discharging authorization: When a high-pressure puffing tank completes the puffing process, it sends a "pending discharge" signal to the central control system. The system queries the real-time material level L of the intermediate treatment and buffer tank. Only when L < L_high (such as 70% capacity), it sends an "allow discharge" instruction to this tank.

[0082] Sequential discharging: If multiple high-pressure puffing tanks request discharging simultaneously, the system authorizes according to the principle of "the first completed first out". Only one high-pressure puffing tank discharges at a time, and the material enters the intermediate treatment and buffer tank 2 through the main aggregate pipeline.

[0083] Buffering and pretreatment: In the intermediate treatment and buffer tank 2, the material is purified and homogenized by the continuously purged inert gas. When the material level L > L_high, the system suspends all discharging authorizations; when the material level drops to L < L_low (such as 20% capacity) due to feeding downstream, the system automatically triggers the authorization for the next queued high-pressure puffing tank to discharge.

[0084] During this process, the material is purified and homogenized by the continuously purged inert gas while being temperature-controlled by the heating system. First, it is temperature-controlled under the condition of not higher than 200°C for 0.5 - 1.5 hours of inert gas purging. Subsequently, the heating power is increased, and the temperature is raised to the preset pre-removal-of-impurities temperature of the system within 0.5 - 1 hour, and kept warm for not less than 0.5 hours for preheating and impurity removal. At the pre-removal-of-impurities temperature of about 400 - 500°C, a part of the substances that can volatilize at low temperature can be excluded in advance, reducing the residence time of the next vacuum high-temperature furnace 3 in the low-temperature section and increasing the heating rate of the vacuum high-temperature furnace 3. At the same time, this temperature range will not put pressure on the temperature resistance of the intermediate treatment and buffer tank 2, reducing the requirement for the overall heat resistance of the intermediate treatment and buffer tank 2.

[0085] After the preheating and impurity removal time ends, the cooling system is started to assist in cooling down, and the material temperature is reduced from the pre-removal-of-impurities temperature to below 150°C before discharging, meeting the safety working temperature requirements of vacuum feeding and preparing for discharging.

[0086] S4. Continuous feeding and high-temperature treatment:

[0087] The intermediate treatment and buffer tank 2 feeds the vacuum high-temperature furnace 3 through the vacuum feeding valve. During normal continuous production, the lower end of the intermediate treatment and buffer tank 2 discharges materials at a stable cycle, and intermittently but continuously feeds the vacuum high-temperature furnace 3 through the vacuum feeding valve to ensure the connection of processes and continuous production.

[0088] In the vacuum high-temperature furnace 3, the material successively undergoes high-temperature purification and high-temperature recasting treatments. Specifically, the high-temperature treatment is divided into three stages:

[0089] The first-stage high-temperature vacuum purification:

[0090] Under vacuum conditions below 10 Pa, the temperature is increased to 1800-2200℃ at a rate of 5-15℃ / min and held for 2-5 hours. During this stage, low-melting-point and volatile impurities (such as potassium, sodium, zinc and other metals) will overflow from the graphite matrix and be continuously removed by the vacuum unit 5.

[0091] Second-stage pulse reaction purification:

[0092] While maintaining a temperature of 1800-2200℃, the pulse control valve of the reaction gas source is controlled by the central control system to alternately introduce CF4 and Ar into the furnace in a pulsed manner, maintaining the furnace pressure at no higher than 100Pa. Preferably, one pulse cycle is: CF4 is introduced for 10-30 minutes -> CF4 is stopped, and Ar is introduced for 20-40 minutes, this process is repeated 8-15 times. CF4 decomposes at high temperature to produce active fluorine atoms, which react with metallic impurities in graphite (such as Fe, Al, Ca, Mg, etc.) to form volatile fluorides (such as FeF3, AlF3). It can also react with oxides to form fluoride oxides or fluorides. The pulsed introduction method avoids excessive carbon atmosphere in the furnace caused by continuous decomposition of CF4. The intermittent introduction of inert gas Ar can promptly purge the gaseous fluorides generated by the reaction and remove them by the vacuum unit 5, thereby greatly improving the impurity removal efficiency and reducing the consumption of ineffective CF4.

[0093] Third stage high-temperature recasting:

[0094] Turn off the CF4 gas source and continuously introduce a small amount of Ar gas as a protective gas. Further raise the furnace temperature to 2500-2800℃ at a rate of 5-15℃ / min and hold for 2-4 hours. This high-temperature process can thoroughly decompose and remove residual trace impurities. More importantly, the high-temperature thermal energy can "anneal" and "recrystallize" the graphite crystal structure that was damaged in the previous steps due to expansion, depressurization and chemical reaction, repair lattice defects, significantly improve the graphitization degree of the material, and restore its electrical conductivity, thermal conductivity and thermal stability to the optimal state.

[0095] After high-temperature recasting is completed, heating is stopped, and the material is allowed to cool naturally to 100°C below room temperature under Ar gas protection. Then, the supply of protective gas is stopped, and ultra-high purity semiconductor-grade graphite material can be obtained after the material is removed from the furnace.

[0096] In summary, this invention, through its original multi-stage purification path of "high-pressure expansion - intermediate purification - high-temperature treatment," enables semi-continuous production, significantly improving efficiency and capacity. The parallel operation of the high-pressure expansion tank group, intermediate treatment, and buffer tank breaks through the bottleneck of traditional pure batch production. High-pressure expansion can be performed in parallel, while vacuum high-temperature treatment allows for continuous feeding, resulting in a significant increase in system capacity and high equipment utilization. The system adopts semi-continuous production, increasing overall capacity by approximately 50% or more compared to traditional pure batch high-temperature furnaces. This multi-stage purification path offers high purification efficiency and extremely high product purity. High-pressure expansion creates the prerequisites for subsequent deep impurity removal, avoiding the limitations of relying solely on high-temperature chemical reactions. The intermediate treatment and buffer, while buffering and homogenizing the material, perform medium-temperature purging pre-removal, removing some low-temperature volatile components in advance, significantly reducing the burden on the downstream vacuum high-temperature furnace, shortening its processing time in the low-temperature section, and improving overall energy efficiency. This invention employs a CF4 / Ar pulsed reaction in the pulsed reaction impurity removal and high-temperature recasting stages to efficiently remove metallic impurities while avoiding excessive carbonization caused by continuous CF4 flow. The final high-temperature recasting not only completely removes trace residual impurities but, more importantly, repairs the graphitized structure, achieving both "ultra-high purity" and "high graphitization degree"—two key indicators. The high-purity graphite material processed by this system has an ash content not exceeding 2 ppm, and under optimized processes, it can reach below 1 ppm. The final product's graphitization degree can reach over 98%. This invention also features intelligent control, ensuring good product consistency. The central control system provides global scheduling, intelligently controlling the operation sequence of each unit (such as staggered expansion, intelligent discharge authorization, and pulsed gas supply) through real-time feedback of signals such as material level and temperature. This ensures the accuracy and stability of process parameters, greatly improving product consistency and reliability. The ash content deviation between different production batches can be controlled within ±0.2 ppm, and the deviation of key physical properties (such as thermal conductivity) is <4%, meeting the stringent requirements for material performance in semiconductor applications.

[0097] The above embodiments are merely preferred implementations of the present invention. For those skilled in the art, any modifications or improvements made without departing from the concept of the present invention should fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A purification system for high-purity graphite materials for semiconductors, characterized in that, include: High-pressure expansion tank group (1): It consists of at least two high-pressure expansion tanks that are set in parallel and can be operated independently. The bottom outlet of each high-pressure expansion tank is connected to a common main collection pipeline through a high-temperature and high-pressure resistant valve. Each high-pressure expansion tank is equipped with an independent heating system and a cooling system. Intermediate processing and buffer tank (2): The inlet is connected to the high-pressure expansion tank group (1) through the main collection pipeline. The tank body is a sealable pressure vessel equipped with an inert gas purging system. The effective volume is more than 2.5 times the loading capacity of a single high-pressure expansion tank. It is equipped with a level gauge and a temperature sensor, as well as a heating system and a cooling system. The material is continuously purged with inert gas while the temperature is controlled in the intermediate processing and buffer tank (2) for purification and homogenization. Vacuum high temperature furnace (3): The feed port is connected to the outlet of intermediate processing and buffer tank (2) through a vacuum feed valve; Gas supply system (4): connected to high pressure expansion tank group (1), intermediate processing and buffer tank (2), and vacuum high temperature furnace (3), used to supply working gas to high pressure expansion tank group (1), intermediate processing and buffer tank (2), and vacuum high temperature furnace (3); Vacuum unit (5): connected to vacuum high temperature furnace (3) to provide a vacuum environment for vacuum high temperature furnace (3); Central control system: It is electrically connected to the sensors and actuators of each high pressure expansion tank in the high pressure expansion tank group (1), the level gauges and temperature sensors of the intermediate processing and buffer tank (2), and all pumps, valves and mass flow controllers of the system, and schedules each high pressure expansion tank in the high pressure expansion tank group (1) to start the expansion program in sequence and staggered peak.

2. The purification system according to claim 1, characterized in that, The single high-pressure expansion tank of the high-pressure expansion tank group (1) can withstand a working pressure of not less than 5MPa.

3. The purification system according to claim 2, characterized in that, The individual high-pressure expansion tank of the high-pressure expansion tank group (1) can withstand a working temperature of not less than 600℃.

4. The purification system of claim 1, wherein, The cooling system of the intermediate processing and buffer tank (2) adopts a cooling jacket structure.

5. The purification system of claim 1, wherein, The vacuum feed valve is a gate valve with a locking chamber.

6. A method for purifying high-purity graphite material for semiconductors, employing the purification system described in any one of claims 1-5, characterized in that, Including the following steps: S1. Pre-processing and distributed loading: The graphite powder raw material is distributed and loaded into each high-pressure expansion tank in the high-pressure expansion tank group (1); S2, Parallel high-pressure expansion treatment: The central control system schedules each high-pressure expansion tank in the high-pressure expansion tank group (1) to start the expansion program in a staggered manner. S3. Discharge and intermediate processing: After high-pressure expansion, the material enters the intermediate treatment and buffer tank (2) through the main collection pipeline. In the intermediate treatment and buffer tank (2), the temperature is controlled while inert gas is continuously blown out to purify and homogenize it. S4. Continuous feeding and high-temperature treatment: The intermediate processing and buffer tank (2) feeds the material to the vacuum high temperature furnace (3) through the vacuum feeding valve. The material in the furnace undergoes high temperature purification and high temperature recasting treatment in sequence. After the treatment is completed, the process is controlled to cool down and the final high-purity graphite product is obtained after exiting the furnace.

7. The purification method according to claim 6, characterized in that, In step S2, the expansion process is as follows: inert gas is introduced to 2-4 MPa, heated to 300-500°C and kept at that temperature for 1-3 hours, and then the pressure is released instantly.

8. The purification method according to claim 6, characterized by, The high-temperature treatment in step S4 consists of three stages: The first stage is high-temperature vacuum purification: under vacuum conditions, the temperature is raised to 1800-2200℃ and held to remove volatile impurities; The second stage is pulse reaction impurity removal: CF4 / Ar is alternately introduced in a pulsed manner to remove metallic impurities; The third stage involves high-temperature recasting: heating to 2500-2800℃ and holding at that temperature to repair the graphitized structure.

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