Perfluoroether rubber composition as well as preparation method and application thereof

Abstract

The invention discloses a perfluoroether rubber composition, a preparation method and application, belongs to the technical field of semiconductor sealing materials, and aims to solve the problems that a cross-linked network of existing perfluoroether rubber is unstable in a high-temperature and acid plasma environment, inorganic filler is easy to etch and precipitates are too high. The perfluoroether rubber composition is prepared from the following raw and auxiliary materials in parts by weight: 100 parts of raw perfluoroether rubber, 3-5 parts of an imine amidine vulcanizing agent, 5-10 parts of a surface perfluorinated filler and 0.1-2.0 parts of a processing aid. The composition has extremely high thermochemical stability, excellent plasma etching resistance and extremely low volatile organic compound precipitation. The method is mainly applied to semiconductor wafer manufacturing and sealing of panel display equipment in a high-temperature and high-corrosion environment.

Description

Technical Field

[0001] This invention belongs to the technical field of polymer materials and semiconductor manufacturing supporting materials, specifically relating to a perfluoroether rubber composition, its preparation method, and its application. Background Technology

[0002] As semiconductor integrated circuit manufacturing processes advance towards 7nm, 5nm, and more advanced processes, extremely stringent requirements are placed on sealing materials used in production equipment. These seals need to maintain stable resilience and sealing performance over long periods in environments exceeding 300°C, high-energy plasma bombardment, and various corrosive gases, while simultaneously requiring extremely low metal ion release and extremely low total organic volatile matter (TVOC) emissions to prevent wafer contamination. In existing technologies, perfluoroelastomers (PFEs) possess excellent chemical stability due to their perfluorinated molecular backbone. However, existing FFEs still have the following problems:

[0003] 1. Limitations of Crosslinking Systems: Traditional bisphenol or peroxide vulcanization systems lack sufficient heat resistance; while conventional triazine crosslinking systems typically use organotin catalysts such as tetraphenyltin, or triallyl isocyanurate (TAIC) as a co-crosslinking agent. The former can lead to metal contamination, while the latter, TAIC, contains a non-fluorinated allyl group in its molecule, making it prone to chemical degradation at temperatures above 300°C or in strongly acidic plasma environments, resulting in loss of elasticity in the seals.

[0004] 2. Filler interface defects: To improve mechanical strength, inorganic fillers such as silica or alumina are usually added. However, conventional fillers contain a large number of hydroxyl groups on their surface, making them hydrophilic and incompatible with the highly hydrophobic perfluoroether rubber matrix. This not only leads to filler agglomeration but also creates weak points at the interface, making them susceptible to preferential etching by plasma and generating microparticles that contaminate the cavity.

[0005] Chinese patent CN116694005A discloses a high-temperature resistant perfluoroether rubber composition and its preparation method. It is prepared by adding cerium oxide as a processing aid to the formulation of perfluoroether rubber raw rubber, filler and crosslinking agent, and using a conventional dry mechanical mixing method with an internal mixer and a two-roll mill. However, due to the use of conventional dry mixing, it is difficult to ensure that the nanofiller is uniformly dispersed at the molecular level in the matrix. In addition, there are active hydroxyl sites on the surface of the filler. Furthermore, the introduction of metal oxide additives leads to the risk of filler migration and precipitation and metal ion contamination in the harsh service environment of semiconductors.

[0006] Therefore, developing a novel FFKM material system that can significantly reduce plasma etching rate, suppress particle generation through strong interface anchoring, and meet the requirements of ultra-cleanliness and low precipitation is an urgent need in the field of semiconductor sealing materials. Summary of the Invention

[0007] The present invention aims to solve the technical problems of existing perfluoroether rubber sealing materials, such as poor corrosion resistance in semiconductor plasma environment, easy detachment of fillers causing particulate contamination, and large permanent deformation under high temperature compression.

[0008] The specific technical solution is as follows:

[0009] A perfluoroether rubber composition, wherein the perfluoroether rubber composition is prepared from the following raw and auxiliary materials in parts by weight: 100 parts of perfluoroether rubber raw rubber, 3-5 parts of imine amidine vulcanizing agent, 5-10 parts of surface perfluorinated filler, and 0.1-2.0 parts of processing aid; wherein the surface perfluorinated filler is a two-scale inorganic filler system with surface modified by gas-phase fluorination; the chemical formula of the imine amidine vulcanizing agent is: .

[0010] Furthermore, the dual-scale inorganic filler system includes fumed silica and spherical silica, wherein the primary particle size of the fumed silica is 10-16 nm; the average particle size of the spherical silica is 300 nm; and the weight ratio of the fumed silica to the spherical silica is 1:(3-5).

[0011] Furthermore, the conditions for the gas-phase fluorination modification are as follows: under the condition of a mixed gas flow of fluorine and nitrogen, the dual-scale inorganic packing system is subjected to a gas-phase fluorination reaction. The gas-phase fluorination reaction is carried out using a temperature gradient control method: the initial reaction temperature is controlled at 70°C and maintained for 30 minutes, then the temperature is increased to 100°C and the reaction continues until no hydrogen fluoride is detected in the tail gas. After the reaction is completed, the residual fluorine is replaced by purging with high-purity nitrogen. The volume ratio of fluorine to nitrogen is 1:4.

[0012] Furthermore, the aforementioned , where R f ′ is perfluorohexyl, R f The perfluorohexamethylene, perfluorodimethylene, or perfluorocyclohexyl group is used, specifically including perfluorohexamethylene-bisperfluorohexylimine amidine, perfluorodimethylene-bisperfluorohexylimine amidine, or perfluorocyclohexyl-bisperfluorohexylimine amidine; the perfluoroether rubber raw rubber has a molar ratio of tetrafluoroethylene:perfluoroalkyl vinyl ether:perfluoro(4-cyanobutyl) vinyl ether = 84.5:14:1.5; the processing aid is perfluoropolyether oil.

[0013] Furthermore, the preparation method of the perfluoroether rubber composition includes the following steps:

[0014] S1: The dual-scale inorganic packing is pretreated under heating and vacuum conditions to remove the moisture adsorbed on the surface and in the pores of the packing; then the gas-phase fluorination modification is performed to obtain a surface-perfluorinated packing.

[0015] S2: Add the raw perfluoroether rubber to a perfluoro solvent and stir at 50-60°C to form a slurry. Then add the surface perfluorinated filler and processing aids obtained in step S1. After high-speed shear dispersion, the system temperature drops to below 40°C. Then add an imine-amidine vulcanizing agent and stir to mix evenly to obtain a mixed slurry.

[0016] S3: The mixed adhesive solution is placed under vacuum to perform a devolatilization treatment to obtain perfluoroether rubber premixed blocks;

[0017] S4: The perfluoroether rubber premixed block is placed in a mold for a first-stage compression vulcanization, and then placed in a nitrogen atmosphere for a second-stage temperature-increasing vulcanization to obtain the perfluoroether rubber product.

[0018] Furthermore, the pretreatment conditions described in step S1 are vacuum treatment at 200°C for 30-60 minutes.

[0019] Further, the perfluorinated solvent in step S2 is perfluoro(2-methylpropyl) ether or perfluorohexyl isopropyl ether; the solid content of the adhesive is 10-15 wt%; and the high-speed shear dispersion conditions are: dispersion at 3000-5000 rpm for 30 minutes.

[0020] Furthermore, the devolatilization treatment in step S3 is specifically as follows: First, at room temperature, the system pressure is gradually reduced at a rate of 0.03 MPa / min until the vacuum degree reaches -0.098 MPa, and this condition is maintained for 50 minutes; then, under vacuum conditions, a segmented heating treatment is performed. In the first stage, the temperature is raised to 60°C and held for 60 minutes. In the second stage, the temperature is further raised to 80°C and held until no more bubbles are generated inside the colloid.

[0021] Furthermore, the conditions for the first-stage compression vulcanization in step S4 are: temperature 170℃, pressure 15MPa, and time 15 minutes; the steps for the second-stage programmed temperature-increasing vulcanization are as follows: heating to 200℃ and holding for 4 hours; heating to 250℃ and holding for 4 hours; heating to 310℃ and holding for 8 hours.

[0022] Furthermore, the perfluoroether rubber composition is used to prepare a sealing material for semiconductor manufacturing equipment, the sealing material being suitable for resisting plasma etching or chemical vapor deposition process environments.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) This invention achieves surface perfluorination by surface fluorination modification of dual-scale inorganic fillers, eliminating the active hydroxyl groups on the surface and transforming them into an inert fluorinated layer. This not only improves the thermodynamic compatibility between the filler and the perfluorinated matrix, but also eliminates the "anchor points" of plasma attack, significantly reducing the etching weight loss rate. Furthermore, the specific dual-scale filler compound, with small-diameter particles providing reinforcement and large-diameter particles providing support, maintains excellent high-temperature compression resilience while ensuring high modulus.

[0025] (2) This invention employs a wet mixing process assisted by perfluorinated solvents, avoiding the high shear temperature rise and uneven filler caused by dry mixing in traditional open mills. Combined with a high-temperature two-stage vulcanization process under vacuum and inert atmosphere, it can effectively remove small molecule oligomers and residual solvents, enabling the products to meet advanced process cleanliness standards. At the same time, because the system of this invention achieves excellent processability and vulcanization efficiency through the design of the vulcanizing agent and the surface perfluorinated filler, it can obtain excellent performance without the need to add additional vulcanizing agents and metal oxide acid absorbers, thereby further reducing the risk of potential precipitation sources and impurity contamination.

[0026] (3) The present invention uses an imine-amidine vulcanizing agent, which is a perfluorinated structure and can react with the nitrile group of the perfluoroether rubber raw rubber to form a thermally stable heterocyclic structure, thereby significantly improving the anti-aging performance of the material in high temperature and acidic gas environment. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation process of the perfluoroether rubber composition of the present invention.

[0028] Figure 2 This is a comparison chart of the test results for elongation at break, high-temperature compression set, and resistance to plasma etching of the embodiments and comparative examples of the present invention.

[0029] Figure 3 This is a comparison chart of the cleanliness test results of the embodiments and comparative examples of the present invention. Detailed Implementation

[0030] The following embodiments further explain and illustrate the technical solutions of the present invention. It should be specifically noted that each specific embodiment is a concretization and explanation of the technical solution and should not be considered as a limitation on the scope of protection of the present invention. Those skilled in the art still have the right to modify the technical solutions of these embodiments and make equivalent substitutions for some or all of the technical features, and these modifications or substitutions do not change the essence of the corresponding technical solutions, nor do they cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions described in the present invention.

[0031] This invention proposes a perfluoroether rubber composition, its preparation method, and its application. The perfluoroether rubber composition is prepared from the following raw and auxiliary materials in parts by weight: 100 parts of perfluoroether rubber raw rubber, 3-5 parts of imine amidine vulcanizing agent, 5-10 parts of surface perfluorinated filler, and 0.1-2.0 parts of processing aid. (See attached...) Figure 1 The diagram shows the preparation process of the perfluoroether rubber composition of the present invention. The specific preparation steps are as follows:

[0032] S1. Packing Pretreatment

[0033] Fumed silica and spherical silica were placed in a fluidized bed reactor with a nickel-based alloy liner. The temperature was raised to 200°C and treated under vacuum for 30-60 minutes to thoroughly remove adsorbed water from the surface and pores of the packing material. Subsequently, a mixture of fluorine and nitrogen gas was introduced for a gas-phase fluorination reaction, with a fluorine to nitrogen volume ratio of 1:4. The gas-phase fluorination reaction was carried out using a temperature gradient control method. The initial reaction temperature was controlled at 70°C and maintained for 30 minutes to preferentially fluorinate the exposed hydroxyl groups on the packing surface. The temperature was then slowly raised to 100°C and the reaction continued to promote the layer-by-layer fluorine substitution of the hydroxyl groups on the packing surface, forming a continuous, dense, and stable inorganic fluorinated surface layer. This process avoided damage to the main silica lattice structure, ensuring the stability of the two-scale packing structure. The reaction continued until no hydrogen fluoride was detected in the exhaust gas, indicating that the hydroxyl groups on the packing surface had been replaced by fluorine atoms, forming a stable inorganic fluorinated surface layer. After the reaction, the residual fluorine gas was replaced by high-purity nitrogen gas to obtain a fully fluorinated packing material.

[0034] The fumed silica has a primary particle size of 10-16 nm; the spherical silica has an average particle size of 300 nm; and the weight ratio of the fumed silica to the spherical silica is 1:(3-5).

[0035] The above-mentioned surface fluorination modification eliminates the active hydroxyl sites on the surface of inorganic fillers, significantly reducing surface energy; it avoids the organic coating layer formed by traditional coupling agent modification, reducing potential precipitates from the source; it improves the thermodynamic compatibility between fillers and perfluorinated matrix, making it easier for fine-particle fillers to be coated and fixed by rubber segments during subsequent processing and vulcanization, thereby reducing the risk of migration and shedding of nanoscale particles during service.

[0036] S2. Wet Mixing

[0037] In a reactor equipped with a stirrer and reflux condenser, a perfluorinated solvent is added, and the temperature is raised to 50-60°C. Perfluoroether rubber raw material is added according to the formulation, and the mixture is stirred until a complete solution is formed, controlling the solid content to 10-15 wt%. Subsequently, under continuous stirring, the surface-perfluorinated filler and processing aids prepared in step S1 are added in batches. Since the filler surface is perfluorinated, it exhibits good wettability and dispersion stability in the perfluorinated solvent. A high-shear homogenizer is used to disperse the filler at 3000-5000 rpm for 30 minutes, ensuring that fine-sized fillers are uniformly embedded between the rubber molecular chain network, while larger-sized fillers form a stable skeletal support structure. After dispersion, the system temperature is lowered to below 40°C, and an imine-amidine vulcanizing agent is added. The mixture is stirred at low speed for 30 minutes to avoid localized enrichment of the vulcanizing agent, resulting in a uniform and stable mixed solution.

[0038] The perfluoroether rubber raw rubber has a molar ratio of tetrafluoroethylene: perfluoroalkyl vinyl ether: perfluoro(4-cyanobutyl) vinyl ether = 84.5:14:1.5. The imine amidine vulcanizing agent is... , where R f ′ is perfluorohexyl, R f It is perfluorohexamethylene, perfluorodimethylene, or perfluorocyclohexyl, specifically including perfluorohexamethylene-bisperfluorohexylimine amidine, perfluorodimethylene-bisperfluorohexylimine amidine, or perfluorocyclohexyl-bisperfluorohexylimine amidine. The processing aid is perfluoropolyether oil.

[0039] The perfluorinated solvent is perfluoro(2-methylpropyl) ether or perfluorohexyl isopropyl ether, which has good wettability and dispersibility for surface-perfluorinated dual-scale inorganic fillers, ensuring that the fillers are uniformly embedded in the rubber molecular network to form a stable mixed solution, and reducing the viscosity of the system to facilitate subsequent operations and vulcanization molding.

[0040] This step, through wet dispersion and molecular-level wetting, ensures that the inorganic filler is fully coated by the rubber chains before vulcanization, laying the foundation for the formation of a stable filler-rubber-crosslinked network structure during the subsequent vulcanization process.

[0041] S3. Deviation and Preforming

[0042] The mixed adhesive obtained in step S2 was uniformly spread in a container with an inert surface and subjected to devolatilization under vacuum. During the devolatilization process, the system pressure was first gradually reduced at a rate of 0.03 MPa / min at room temperature until the vacuum level reached -0.098 MPa, and this condition was maintained for 50 minutes. Most of the perfluorinated solvent in the system was recovered under reduced pressure to avoid violent boiling of the solvent during the heating process. Subsequently, a staged heating process was performed while maintaining vacuum. In the first stage, the temperature was raised to 60°C and held for 60 minutes. In the second stage, the temperature was further raised to 80°C to allow the residual solvent to slowly escape. The temperature was then maintained until no more bubbles were generated inside the colloid, resulting in a dense perfluoroether rubber premix block with uniform filler distribution.

[0043] During the aforementioned devolatilization process, the combination of gradient decompression and segmented heating effectively suppressed internal convection and filler migration caused by rapid solvent evaporation, preventing the enrichment or localized precipitation of inorganic fillers on the colloid surface. This slow and controllable devolatilization process helps maintain the in-situ distribution of inorganic fillers in the rubber matrix, thereby reducing the potential risk of particle precipitation due to solvent residue or internal micropore formation, and providing a stable microstructural basis for subsequent vulcanization molding and high-temperature service processes.

[0044] S4. Vulcanization molding

[0045] The premixed rubber block is passed through a two-roll mill several times to facilitate further degassing and sheet formation, then sheeted. The sheet is placed in a preheated mold and vulcanized on a flat vulcanizing machine at 170°C. After mold closing, five pressurization-depressurization degassing operations are performed to remove residual air and volatiles generated in the early stages of vulcanization. The pressure is then increased to 15 MPa and held for 15 minutes. During this process, the imine amidine groups react with the nitrile groups on the rubber chains to form a pre-crosslinked network. The product is removed and placed in an inert gas oven with gas circulation and forced degassing functions. Throughout the two-stage vulcanization process, a continuous flow of high-purity nitrogen is introduced to maintain a positive pressure environment inside the oven to prevent high-temperature oxidation. Simultaneously, the flowing nitrogen acts as a carrier gas to promptly remove reaction byproducts from the system. The following heating procedure is then followed:

[0046] First stage: Heat to 200℃ and hold for 4 hours to complete the main reaction and remove the byproduct ammonia.

[0047] Second stage: Heat to 250℃ and hold for 4 hours to further increase cross-linking density and improve network structure;

[0048] The third stage: heat up to 310℃ and keep warm for 8 hours to eliminate internal stress and remove residual low-molecular-weight volatiles.

[0049] After naturally cooling to room temperature, the finished product is obtained through cleaning and inspection.

[0050] The three-stage high-temperature post-curing process described above involves: completing the main cross-linking reaction between imine amidine groups and nitrile groups in the 200-250℃ range to construct a highly thermally stable cross-linked network; and in the 310℃ high-temperature stage, fully releasing internal stress under an inert atmosphere and thoroughly removing low-molecular-weight byproducts and any unreacted small molecules. This multi-stage post-curing process not only improves the material's high-temperature resistance and plasma resistance but also serves as a secondary purification process, effectively reducing the risk of volatile release and particulate precipitation under semiconductor equipment service conditions.

[0051] The following examples and comparative examples all use the same batch of perfluoroether rubber raw rubber: molar ratio of tetrafluoroethylene: perfluoroalkyl vinyl ether: perfluoro(4-cyanobutyl) vinyl ether = 84.5:14:1.5.

[0052] Example 1

[0053] The perfluoroether rubber composition by weight is as follows: 100 parts perfluoroether rubber raw rubber; 4 parts perfluorohexamethylene-bisperfluorohexylimine amidine; 1.6 parts fumed silica with a native particle size of 12 nm; 6.4 parts spherical silica with an average particle size of 300 nm; and 1 part perfluoropolyether oil.

[0054] The preparation process is as follows:

[0055] (1) Dry fumed silica and spherical silica were placed in a fluidized bed reactor with a nickel-based alloy liner. The temperature was raised to the reaction temperature of 200°C and treated under vacuum for 40 minutes. Then, a mixed gas with a volume ratio of fluorine to nitrogen of 1:4 was introduced, and the flow rate was controlled to keep the powder in a fluidized state. The initial reaction temperature was controlled at 70°C and maintained for 30 minutes. Then, the temperature was raised to 100°C and the reaction was continued for 4 hours. No hydrogen fluoride was detected in the tail gas, and the reaction was terminated. The residual fluorine was replaced by purging with high-purity nitrogen to obtain a two-scale inorganic filler with a perfluorinated surface.

[0056] (2) In a reactor equipped with a stirring and reflux condenser, 733 parts of perfluorohexyl isopropyl ether were added, and the temperature was raised to 55°C. Perfluoroether rubber raw material was added according to the formula amount, and the mixture was stirred until a liquid was formed with a solid content of 12 wt%. Subsequently, under continuous stirring, the surface perfluorinated filler prepared in step (1) and 1 part of perfluoropolyether oil were added in batches. The mixture was dispersed for 30 minutes at a speed of 3000-5000 rpm using a high-shear homogenizer. After dispersion, the system temperature was lowered to below 40°C, and perfluorohexamethylene-bisperfluorohexylimine amidine was added. The mixture was stirred at low speed for 30 minutes to obtain a uniform and stable mixed liquid.

[0057] (3) Spread the mixed adhesive obtained in step (2) evenly in a container with an inert surface and place it in a vacuum oven for devolatilization treatment: First, at room temperature, gradually reduce the system pressure at 0.03 MPa / min until the vacuum degree is -0.098 MPa, and maintain this condition for 50 minutes. Then, while maintaining the vacuum condition, raise the temperature to 60°C, keep it at that temperature for 60 minutes, and then raise the temperature to 80°C and keep it at that temperature until no more bubbles are generated inside the colloid, thus obtaining a perfluoroether rubber premixed block.

[0058] (4) After the premixed rubber block is passed through a two-roll mill four times, it is sheeted out. The sheet is placed in a preheated mold and vulcanized on a flat vulcanizing machine. The mold temperature is set to 170°C. After the mold is closed, five pressurization-depressurization and degassing operations are performed to remove residual air and volatiles generated in the early stage of the vulcanization reaction. Then the pressure is increased to 15 MPa and vulcanized for 15 minutes. The product is then removed and placed in an inert gas oven with gas circulation and forced degassing functions for a second stage of vulcanization. High-purity nitrogen is continuously introduced and the temperature is raised according to the following procedure: First stage: heat up to 200°C and hold for 4 hours; Second stage: heat up to 250°C and hold for 4 hours; Third stage: heat up to 310°C and hold for 8 hours. Finally, it is naturally cooled to room temperature and cleaned to obtain the perfluoroether rubber product of this invention.

[0059] Example 2

[0060] The perfluoroether rubber composition is formulated in parts by weight as follows: 100 parts perfluoroether rubber raw rubber; 3 parts perfluorodimethylene-bisperfluorohexylimine amidine; 1.2 parts fumed silica with a native particle size of 10 nm; 3.8 parts spherical silica with an average particle size of 300 nm; and 0.1 parts perfluoropolyether oil.

[0061] Preparation process:

[0062] (1) Dry fumed silica and spherical silica were placed in a fluidized bed reactor with a nickel-based alloy liner. The temperature was raised to the reaction temperature of 200°C and treated under vacuum for 30 minutes. Then, a mixed gas with a volume ratio of fluorine to nitrogen of 1:4 was introduced, and the flow rate was controlled to keep the powder in a fluidized state. The initial reaction temperature was controlled at 70°C and maintained for 30 minutes. Then, the temperature was raised to 100°C and the reaction was continued for 2 hours. No hydrogen fluoride was detected in the tail gas, and the reaction was terminated. The residual fluorine was replaced by purging with high-purity nitrogen to obtain a two-scale inorganic filler with a perfluorinated surface.

[0063] (2) In a reactor equipped with a stirring and reflux condenser, 900 parts of perfluoro(2-methylpropyl) ether were added, and the temperature was raised to 50°C. Perfluoroether rubber raw material was added according to the formula amount, and the mixture was stirred until a liquid was formed with a solid content of 10 wt%. Subsequently, under continuous stirring, the surface-perfluorinated dual-scale inorganic filler prepared in step (1) was added in batches. The mixture was dispersed for 30 minutes at a speed of 3000-5000 rpm using a high-shear homogenizer. After dispersion, the system temperature was lowered to below 40°C, and perfluorodimethylene-bisperfluorohexylimine amidine was added. The mixture was stirred at low speed for 30 minutes to obtain a uniform and stable mixed liquid.

[0064] Steps (3) and (4) are the same as in Example 1, and the perfluoroether rubber product of the present invention is finally obtained.

[0065] Example 3

[0066] The perfluoroether rubber composition by weight is as follows: 100 parts perfluoroether rubber raw rubber; 5 parts perfluorocyclohexyl-bisperfluorohexylimine amidine; 1.7 parts fumed silica with a primary particle size of 16 nm; 8.3 parts spherical silica with an average particle size of 300 nm; and 2 parts perfluoropolyether oil.

[0067] The preparation process is as follows:

[0068] (1) Dry fumed silica and spherical silica were placed in a fluidized bed reactor with a nickel-based alloy liner. The temperature was raised to the reaction temperature of 200°C and treated under vacuum for 60 minutes. Then, a mixed gas with a volume ratio of fluorine to nitrogen of 1:4 was introduced, and the flow rate was controlled to keep the powder in a fluidized state. The initial reaction temperature was controlled at 70°C and maintained for 30 minutes. Then, the temperature was raised to 100°C and the reaction was continued for 6 hours. No hydrogen fluoride was detected in the tail gas, and the reaction was terminated. The residual fluorine was replaced by purging with high-purity nitrogen to obtain a two-scale inorganic filler with a perfluorinated surface.

[0069] (2) In a reactor equipped with a stirring and reflux condenser, 566 parts of perfluorohexyl isopropyl ether were added, and the temperature was raised to 60°C. Perfluoroether rubber raw material was added according to the formula amount, and the mixture was stirred until a liquid was formed with a solid content of 15 wt%. Subsequently, under continuous stirring, the surface-perfluorinated dual-scale inorganic filler prepared in step (1) was added in batches. The mixture was dispersed for 30 minutes at a speed of 3000-5000 rpm using a high-shear homogenizer. After dispersion, the system temperature was lowered to below 40°C, and perfluorocyclohexyl-bisperfluorohexyliminemidane was added. The mixture was stirred at low speed for 30 minutes to obtain a uniform and stable mixed liquid.

[0070] Steps (3) and (4) are the same as in Example 1, and the perfluoroether rubber product of the present invention is finally obtained.

[0071] Comparative Example 1

[0072] The formulation is the same as in Example 1, except that a peroxide vulcanization system is used: 1 part 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane (DBPH); 2 parts TAIC; and 0.5 parts magnesium oxide as an acid scavenger. Preparation process: The perfluoroether rubber raw material is placed on a two-roll mill and plasticized at a roll temperature controlled at 40-60℃. After the raw rubber forms a continuous sheet, surface-treated fumed silica and spherical silica fillers are added sequentially, along with the magnesium oxide acid scavenger. The mixture is repeatedly mixed on the two-roll mill to initially disperse the fillers and acid scavenger in the rubber matrix. Perfluoropolyether processing aids are then added to improve the flowability of the mixture, and mixing continues until the compound is homogeneous. In the later stages of mixing, a peroxide vulcanizing agent and a co-vulcanizing agent are added, and mixing continues to ensure uniform dispersion, resulting in a compound. The resulting compound is sheeted and placed in a mold for initial vulcanization on a flat vulcanizing machine. The vulcanized product is then placed in an oven for a second vulcanization process. The temperature of the second vulcanization process does not exceed 250°C to avoid thermal decomposition of the vulcanizing agent, and finally, the rubber product is obtained.

[0073] Comparative Example 2

[0074] The formulation is the same as in Example 1, except that unfluorinated raw fumed silica and spherical silica are used. Preparation process: Perfluoroether rubber raw material is plasticized on a two-roll mill at a roll temperature of 40-60°C to form a uniform sheet. Unfluorinated raw fumed silica, spherical silica fillers, and perfluoropolyether processing aids are then directly added, and dry mixing is performed multiple times in a thin-pass manner to disperse the fillers in the rubber matrix. Due to the large number of hydroxyl groups and adsorbed water on the filler surface, the viscosity of the system increases significantly during mixing, and the fillers are prone to agglomeration. After the filler mixing is complete, the same vulcanizing agent as in Example 1 is added, and mixing continues until the appearance is uniform, resulting in a compounded rubber. The compounded rubber is sheeted and subjected to a first-stage vulcanization and a second-stage vulcanization process, the same as in Example 1, to finally obtain the rubber product.

[0075] Comparative Example 3

[0076] Same as Example 1, except that only 8 parts of surface-fluorinated modified spherical silica filler are added.

[0077] Performance testing

[0078] 1. Tensile property test

[0079] Refer to GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0080] Sample preparation: The vulcanized rubber products obtained in each embodiment and comparative example were vulcanized into standard rubber sheets with a thickness of 2.0±0.2 mm using a flat vulcanization process. After the sheets were left at room temperature for no less than 24 hours, dumbbell-shaped samples were cut from the vulcanized rubber sheets.

[0081] Test method: The test was conducted on an electronic universal testing machine. The tensile rate was set to 500 mm / min. The tensile strength (MPa) and elongation at break (%) were recorded. No less than five specimens were tested in each group of samples, and the arithmetic mean was taken as the test result.

[0082] 2. High-temperature compression set test

[0083] Refer to GB / T 7759.1-2015 "Determination of Compression Set of Vulcanized Rubber or Thermoplastic Rubber - Part 1: Under Normal and High Temperature Conditions"

[0084] Sample preparation: The vulcanized rubber products obtained in each embodiment and comparative example were molded into standard cylindrical vulcanized rubber specimens with a diameter of 13 mm and a height of 6.0 ± 0.2 mm. After molding, the specimens were placed at room temperature for no less than 24 hours to eliminate molding internal stress.

[0085] Test method: The specimen is placed in a high-temperature compression apparatus under 25% compression ratio and kept at 310℃ for 70 hours. After the test, the specimen is removed and allowed to recover at room temperature for 30 minutes, and the compression set is measured.

[0086] 3. Plasma etching resistance test

[0087] Sample preparation: The vulcanized rubber products obtained in each embodiment and comparative example were prepared into rubber sheets with a thickness of 2.0±0.2mm by compression molding. Test pieces with a size of 10mm×10mm×2mm were cut from the sheets, and the surface of the test pieces was wiped clean and dried for later use.

[0088] Test method: An inductively coupled plasma etching (ICP-E) system was used, with a CF4 / O2 mixture as the etching atmosphere at a volume ratio of 10:1, an RF power of 800W, and a processing time of 1 hour. The sample mass was measured before and after etching, and the mass loss rate was calculated as the plasma etching weight loss rate.

[0089] 4. Total Volatile Organic Compounds (TVOC) Detection

[0090] Sample preparation: The vulcanized rubber products obtained in each embodiment and comparative example were cut into small pieces in a clean environment, and further trimmed or crushed into rubber fragments no larger than 5 mm. 1.0 g was weighed as the test sample.

[0091] Test method: Place the sample in a sealed headspace vial and heat it at 300°C for 30 minutes. Then, inject the sample into a gas chromatography-mass spectrometry system via headspace sampling to determine the total volatile organic compound content, expressed in ppm.

[0092] 5. Liquid particle counting detection

[0093] Sample preparation: The vulcanized rubber products obtained from the various embodiments and comparative examples were directly molded into sealing ring products with practical application forms. The outer surface area of ​​the sealing ring was 100 cm². 2 The product was simply rinsed with ultrapure water and dried before testing.

[0094] Test method: The sample was immersed in ultrapure water and cleaned with ultrasonic waves at 40 kHz for 10 minutes. The cleaning solution was extracted, and the number of particles with a size of 0.1 μm and above was counted using a liquid laser particle counter (LPC). The results are expressed as pcs / ml.

[0095] 6. Detection of average metal cation content

[0096] Sample preparation: The vulcanized rubber products obtained in each example and comparative example were cut into small samples under clean conditions, and 5g was weighed as the test sample. The samples were completely digested in an ultrapure acid system to obtain a clear digestion solution.

[0097] Test method: Inductively coupled plasma mass spectrometry was used to detect no less than 20 common metal elements such as Na, K, Ca, Fe, Cu and Al in the digestion solution. The contents of each metal element were summed to obtain the average metal cation content, and the result was expressed as ppb.

[0098] Table 1. Mechanical properties and plasma etching resistance test results for each embodiment and comparative example.

[0099] Experiment number Tensile strength (MPa) Elongation at break (%) High-temperature compression permanent deformation (310℃ / 70h, %) Plasma weight loss rate (%) Example 1 17.5 210 34 3.65 Example 2 16.4 235 38 3.82 Example 3 18.8 200 32 3.58 Comparative Example 1 16.5 195 70 6.25 Comparative Example 2 15.8 175 58 4.85 Comparative Example 3 18.0 145 45 4.10

[0100] Table 2 Cleanliness test results for each example and comparative example

[0101] Experiment number TVOC (300℃, ppm) LPC particles (>0.1μm, pcs / ml) Average metal cation content (ppb) Example 1 15.0 120 220 Example 2 12.5 105 190 Example 3 16.8 140 250 Comparative Example 1 120.0 850 4000 Comparative Example 2 85.0 2200 800 Comparative Example 3 25.0 280 300

[0102] Analysis of results in Tables 1 and 2:

[0103] (1) The tensile strength, elongation at break, and high-temperature compression set of Examples 1-3 all exhibit excellent performance, as shown in the attached figures. Figure 2This indicates that the material of the present invention can maintain low compression set, high strength, and good ductility even under long-term exposure to ultra-high temperatures, exhibiting stable and coordinated overall mechanical properties. This result demonstrates that the perfluorinated heterocyclic crosslinking structure formed by imine-amidine perfluorinated vulcanizing agents and cyano-containing perfluorinated ether rubber can effectively inhibit crosslink bond breakage and network rearrangement above 300℃, thereby maintaining the thermochemical stability of the rubber network. In contrast, Comparative Example 1, using a peroxide vulcanization system, showed a significant increase in compression set under high-temperature conditions, and the addition of an acid scavenger during preparation resulted in an average metal cation content as high as 4000 ppb in the finished product, making it difficult to meet the dual requirements of high temperature and cleanliness for sealing materials in semiconductor manufacturing equipment.

[0104] (2) Comparative Example 2, due to the use of unfluorinated silica filler, exhibited increased plasma etching weight loss, with TVOC reaching 85.0 ppm, LPC particle size (>0.1 μm) reaching 2200 pcs / ml, and average metal cation content significantly higher than the examples. This indicates that hydroxyl groups / adsorbed water and residual impurities on the filler surface not only weaken interfacial stability and accelerate plasma erosion but also introduce volatile pollution and particle precipitation risks. This invention, through surface perfluorination modification of the dual-scale inorganic filler and combined with a perfluorinated solvent-assisted wet high-shear dispersion process, significantly reduces the volatile components and particle sources in the material. This results in significantly better TVOC, LPC particle size (>0.1 μm), and average metal cation content in Examples 1-3 compared to the comparative examples, as shown in the attached figures. Figure 3 This better meets the comprehensive requirements of semiconductor equipment sealing for corrosion resistance and cleanliness.

[0105] (3) Although the tensile strength of Comparative Example 3 still reached 18.0 MPa, its elongation at break decreased to 145%, and its high-temperature compression set increased to 45%. This indicates that when only a single spherical silica filler is used, the filler is more likely to locally aggregate in the rubber matrix, resulting in a higher system modulus and increased stress concentration. This makes it difficult for the rubber chain segments to effectively rebound under high-temperature compression conditions, thereby weakening the material's high-temperature elasticity retention and deformation recovery performance. At the same time, the TVOC value, LPC particle number (>0.1 μm), and average metal cation content of Comparative Example 3 are all higher than those of the corresponding embodiment, indicating that the single spherical filler system has limited ability to bind trace impurities on the filler surface. Under high-temperature or plasma etching environments, volatilization or particle peeling is more likely to occur, leading to a decrease in cleanliness performance.

[0106] In summary, this invention, by constructing a perfluorinated heterocyclic highly stable crosslinked network and combining a surface-perfluorinated dual-scale filler system with a perfluorinated solvent dispersion process, achieves synergistic improvements in high-temperature elasticity retention, plasma etching resistance, ultra-low volatile release, low metal contamination, and particle stability. These improvements are significantly superior to traditional peroxide sulfidation systems and comparative schemes without filler surface modification, thus meeting the comprehensive performance requirements of high-end semiconductor manufacturing equipment for sealing materials under extreme operating conditions.

Claims

1. A perfluoroether rubber composition, characterized in that, The perfluoroether rubber composition is prepared from the following raw and auxiliary materials in parts by weight: 100 parts of perfluoroether rubber raw rubber, 3-5 parts of imine amidine vulcanizing agent, 5-10 parts of surface perfluorinated filler, and 0.1-2.0 parts of processing aid; wherein, the surface perfluorinated filler is a two-scale inorganic filler system with surface modified by gas-phase fluorination; the general chemical formula of the imine amidine vulcanizing agent is: .

2. The perfluoroether rubber composition according to claim 1, characterized in that, The dual-scale inorganic filler system includes fumed silica and spherical silica, wherein the primary particle size of the fumed silica is 10-16 nm; the average particle size of the spherical silica is 300 nm; and the weight ratio of the fumed silica to the spherical silica is 1:(3-5).

3. The perfluoroether rubber composition as described in claim 1, characterized in that, The conditions for the gas-phase fluorination modification are as follows: the dual-scale inorganic packing system is subjected to a gas-phase fluorination reaction under a mixed gas flow of fluorine and nitrogen. The gas-phase fluorination reaction is carried out using a temperature gradient control method: the initial reaction temperature is controlled at 70°C and maintained for 30 minutes, then the temperature is increased to 100°C and the reaction continues until no hydrogen fluoride is detected in the tail gas. After the reaction is completed, the residual fluorine is purged with high-purity nitrogen. The volume ratio of fluorine to nitrogen is 1:

4.

4. The perfluoroether rubber composition according to claim 1, characterized in that, The , where R f ′ is perfluorohexyl, R f The perfluorohexamethylene, perfluorodimethylene, or perfluorocyclohexyl group is used, specifically including perfluorohexamethylene-bisperfluorohexylimine amidine, perfluorodimethylene-bisperfluorohexylimine amidine, or perfluorocyclohexyl-bisperfluorohexylimine amidine; the perfluoroether rubber raw rubber has a molar ratio of tetrafluoroethylene:perfluoroalkyl vinyl ether:perfluoro(4-cyanobutyl) vinyl ether = 84.5:14:1.5; the processing aid is perfluoropolyether oil.

5. A method for preparing a perfluoroether rubber composition according to any one of claims 1-4, characterized in that, Includes the following steps: S1: The dual-scale inorganic packing is pretreated under heating and vacuum conditions to remove the moisture adsorbed on the surface and in the pores of the packing; then the gas-phase fluorination modification is performed to obtain a surface-perfluorinated packing. S2: Add the raw perfluoroether rubber to a perfluoro solvent and stir at 50-60°C to form a slurry. Then add the surface perfluorinated filler and processing aids obtained in step S1. After high-speed shear dispersion, the system temperature drops to below 40°C. Then add an imine-amidine vulcanizing agent and stir to mix evenly to obtain a mixed slurry. S3: The mixed adhesive solution is placed under vacuum to perform a devolatilization treatment to obtain perfluoroether rubber premixed blocks; S4: The perfluoroether rubber premixed block is placed in a mold for a first-stage compression vulcanization, and then placed in a nitrogen atmosphere for a second-stage temperature-increasing vulcanization to obtain the perfluoroether rubber product.

6. The preparation method according to claim 5, characterized in that, The pretreatment conditions described in step S1 are vacuum treatment at 200°C for 30-60 minutes.

7. The preparation method according to claim 5, characterized in that, The perfluorinated solvent in step S2 is perfluoro(2-methylpropyl) ether or perfluorohexyl isopropyl ether; the solid content of the adhesive is 10-15 wt%; the high-speed shear dispersion condition is: dispersion at 3000-5000 rpm for 30 minutes.

8. The preparation method according to claim 5, characterized in that, The devolatilization process described in step S3 is as follows: First, at room temperature, the system pressure is gradually reduced at a rate of 0.03 MPa / min until the vacuum reaches -0.098 MPa, and this condition is maintained for 50 minutes; then, under vacuum conditions, a segmented heating process is performed. In the first stage, the temperature is raised to 60°C and held for 60 minutes. In the second stage, the temperature is further raised to 80°C and held until no more bubbles are generated inside the colloid.

9. The preparation method according to claim 5, characterized in that, The conditions for the first-stage compression vulcanization in step S4 are: temperature 170℃, pressure 15MPa, and time 15 minutes; the steps for the second-stage programmed temperature-increasing vulcanization are as follows: heat up to 200℃ and hold for 4 hours; heat up to 250℃ and hold for 4 hours; heat up to 310℃ and hold for 8 hours.

10. The application of the perfluoroether rubber composition according to any one of claims 1-4, characterized in that, The perfluoroether rubber composition is used to prepare a sealing material for semiconductor manufacturing equipment, the sealing material being suitable for resisting plasma etching or chemical vapor deposition process environments.

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