Resin pellets, method for producing the same, and molded product thereof

Abstract

The present invention provides a resin pellet suitable for a molded product used in a semiconductor manufacturing apparatus and inherently having high cleanliness, and a molded product including the resin pellet used in a semiconductor manufacturing apparatus. The present invention provides a resin pellet including at least one selected from tetrafluoroethylene homopolymers or copolymers, wherein an evaporation residue after evaporation and drying of an extract obtained by dissolving and extracting a fluorine-containing substance contained in the resin pellet or adhered to the resin pellet in a fluorine-containing extractant is 20 x 10 ‑6 mg / mm 2 or less.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Japanese Patent Application No. JP2020-131774, filed on August 3, 2020, the disclosure of which is incorporated herein by reference in its entirety. Background Technology

[0003] The present invention relates to resin pellets suitable for molding molded products used in semiconductor manufacturing apparatuses, and molded products molded from the resin pellets and used in semiconductor manufacturing apparatuses, such as molded products for liquid transfer and / or liquid contact.

[0004] As the circuit patterns of semiconductor devices become finer, denser, more integrated, and have more wiring layers, manufacturing processes become more complex and the number of steps continues to increase. Consequently, the size of defects in the circuit patterns of semiconductor devices is becoming increasingly smaller. For this reason, the materials and processes used in semiconductor manufacturing facilities can themselves become sources of contamination, and particles (foreign substances), metallic impurities, chemical contaminants, and other trace (minimum) contaminants in the semiconductor manufacturing environment have an increasingly significant impact on the yield and reliability of semiconductor products (Non-Patent Document 1). In the case of particles, even submicron-sized fine particles can cause defects if they adhere to the wafer surface, so it is even necessary to remove submicron particles. Therefore, in order to suppress the occurrence of circuit pattern defects in fine semiconductor devices and reduce particles larger than the circuit pattern size, the cleanliness (low particle size and low metal content) of the materials and processes used in semiconductor manufacturing facilities to prevent particle adhesion to the wafer is becoming increasingly important.

[0005] In semiconductor manufacturing facilities, the use of fluoropolymer molded products, leveraging the characteristics of fluoropolymers, is increasing. However, particles (contaminating fine particles) easily adhere to the surface of fluoropolymer molded products, and it is difficult to remove even submicron-sized fine particles adhering to the wafer surface, leading to defects that cause failures. Furthermore, these methods require lengthy cleaning times and struggle to achieve the cleanliness levels required for fluoropolymer molded products used in semiconductor manufacturing facilities.

[0006] Therefore, a treatment method for removing fine particles adhering to fluoropolymer molded products used in semiconductor manufacturing has been proposed (Patent Document 1). However, the treatment method proposed in Patent Document 1 requires special equipment for implementation and cannot be implemented by simple means, and it is difficult to achieve a cleanliness level sufficient to meet the requirements of fluoropolymer molded products used in semiconductor manufacturing.

[0007] In addition, chemical solutions used to clean fluoropolymer molded products used in semiconductor manufacturing equipment have issues with high cost and environmental impact.

[0008] Description of related fields

[0009] Patent document 1: Japanese Unexamined Patent Application Publication No. H08-005140.

[0010] Patent document 2: Japanese Unexamined Patent Application Publication No. 2012-518010.

[0011] Non-patent document 1: "New Edition Silicon Wafer Surface Cleaning Technology", Realize Corporation, published by Takeshi Hattori in 2000. Summary of the Invention

[0012] In order to solve the problems of the prior art, the inventors conducted in-depth research and discovered resin pellets with inherent high cleanliness for molding products used in semiconductor manufacturing apparatus, and thus completed the present invention.

[0013] The present invention also provides a molded product comprising resin pellets used in a semiconductor manufacturing apparatus and inherently possessing high cleanliness.

[0014] Problem Solving Methods

[0015] This invention provides resin pellets with high cleanliness for molding molded products used in semiconductor manufacturing apparatus, the resin pellets containing at least one selected from tetrafluoroethylene homopolymers or copolymers, wherein the evaporation residue after evaporation and drying of the extract obtained by dissolving and extracting fluorinated substances contained in or adhered to the resin pellets in a fluorinated extractant is 20 × 10⁻⁶. -6 mg / mm 2 Or less.

[0016] The preferred embodiment of the resin pellets of the present invention is as follows:

[0017] (1) Evaporation residue in the range of 0 to 10 × 10 -6 mg / mm 2 Within the range;

[0018] (2) Evaporation residue in the range of 0 to 1.0 × 10⁻⁶ -6 mg / mm 2 Within the range;

[0019] (3) The tetrafluoroethylene (TFE) copolymer is at least one of the following: TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxane copolymer, TFE / CF2=CFOCF2CF(CF3)OCF2CF2SO2F copolymer, or a mixture of any of these copolymers; and

[0020] (4) The fluorinated extractant is decafluoropentane.

[0021] The present invention also provides a method for producing the above-mentioned resin pellets, the method comprising cleaning the resin pellets containing at least one selected from tetrafluoroethylene homopolymers or copolymers with a fluorinated cleaning agent.

[0022] A preferred embodiment of the method for producing the resin pellets of the present invention is described below:

[0023] (1) The fluorinated cleaning agent is selected from at least one of hydrofluorocarbons, perfluorocarbons, and fluorinated ethers; and

[0024] (2) After cleaning with a fluorinated cleaner, clean with an acidic or alkaline solution.

[0025] The present invention also provides a molded product made from the above-mentioned resin pellets.

[0026] The preferred embodiment of the molded product of the present invention is as follows:

[0027] (1) The evaporation residue after evaporation and drying, obtained by dissolving and extracting fluorine-containing substances contained in or adhering to the molded product in a fluorine-containing extractant, is 20 × 10⁻⁶. -6 mg / mm 2 or less;

[0028] (2) Molded products have hollow parts;

[0029] (3) Cleaning the molded product with a fluorinated cleaning agent, particularly at least one fluorinated cleaning agent selected from hydrofluorocarbons, perfluorocarbons, and fluorinated ethers; and

[0030] (4) After cleaning the molded product with a fluorinated cleaner, clean the molded product with an acidic or alkaline solution.

[0031] Effects of the present invention

[0032] This invention provides a resin pellet suitable for molding molded products used in semiconductor manufacturing apparatuses, and inherently possesses high cleanliness. Because the resin pellet has a melt flow rate (MFR) equivalent to that of the resin pellet before cleaning, it can be used under molding conditions without altering the molded product.

[0033] The present invention provides a fluoropolymer molded product comprising resin pellets used in semiconductor manufacturing apparatus and inherently possessing high cleanliness.

[0034] The present invention provides a molded product that inherently has high cleanliness and is used in semiconductor manufacturing apparatus, such as for liquid transfer or liquid contact, and thus allows the molding product to produce circuit patterns of semiconductor devices while suppressing defects in semiconductor manufacturing apparatuses including the molded product. Detailed Implementation

[0035] Resin pellets

[0036] The resin pellets of the present invention comprise at least one selected from tetrafluoroethylene (TFE) homopolymers or copolymers, and are essentially characterized in that the evaporation residue after evaporation and drying of the extract obtained by dissolving and extracting the fluorinated substances contained in or adhering to the resin pellets in a fluorinated extract is 20 × 10⁻⁶. -6 mg / mm 2 Or less, and with a high degree of cleanliness that enables the proper molding of molded products for use in semiconductor manufacturing facilities.

[0037] Fluorine-containing substances

[0038] The fluorinated material contained in or adhered to the resin pellets of this invention contains carbon and fluorine, and is a fluorinated gaseous decomposition product generated by the thermal decomposition of unstable end groups in the tetrafluoroethylene homopolymer and TFE copolymer, which is cured by lowering the temperature. The fluorinated material is contained in or adhered to the resin pellets in very small amounts.

[0039] Fluorine-containing substances exhibit very low adhesion per unit area and high resistance to hydrocarbon organic solvents, making them difficult to dissolve. Therefore, they are compounds that are undetectable by gas chromatography-mass spectrometry (GC / MS) and difficult to quantify. Furthermore, they are nonpolar to moderately polar compounds with low molecular weights, decomposing at approximately 150°C and evaporating at approximately 300°C or lower.

[0040] Fluorine-containing substances are not preferred because they adhere to the wafer surface during semiconductor manufacturing processes and become nanoscale particles (contaminating fine particles) that cause defects in the circuit patterns of fine semiconductor devices. However, in the resin pellets of the present invention, the aforementioned evaporation residues are as close to zero as possible and reduced to 20 × 10⁻⁶. -6 mg / mm 2 A reading of 0.05 or lower indicates a significant reduction in fluorine content.

[0041] Evaporation residue

[0042] In the resin pellets of the present invention, the evaporation residue after evaporation and drying of the extract obtained by extracting the fluorine-containing substances contained in or adhered to the resin pellets in a fluorine-containing extractant is as close as possible to 0, and ideally 20 × 10⁻⁶. -6 mg / mm 2 Or less, preferably 0 to 10 × 10 -6 mg / mm 2 Within the range, and more preferably within 0 to 1.0 × 10⁻⁶. - 6 mg / mm 2 Within this range. In resin pellets with evaporation residues within this range, the causative agent (fluorine-containing substance) that adheres to the wafer surface during semiconductor manufacturing processes and causes nanoscale particles with a particle size of 300 nm or smaller, particularly 50 nm or smaller, which can create defects in the circuit patterns of fine semiconductor devices is reduced.

[0043] Therefore, the molded product, which includes the resin pellets of the present invention as the molding material, is a fluoropolymer molded product that suppresses the generation of nano-sized particles (contaminating micro-fine particles).

[0044] Besides fluorine-containing substances, substances that contribute to the formation of nanoparticles with a size of 50 nm or smaller include metal ions or fine metal particles. Since metal ions readily combine with fluoride ions, these metal ions or fine metal particles can nucleate and form aggregates of fluorine-containing substances. In this invention, the aggregation of fluorine-containing substances containing such metal ions or fine metal particles can be reduced.

[0045] Metal ions or fine metal particles (bonded metal ions or fine metal particles contained in fluorinated substances) coated with fluorinated substances reduce the dissolving / cleaning effect of acids and alkalis. However, cleaning with the fluorinated cleaning agent described in this invention can remove the fluorinated substances protecting the metal ions or fine metal particles, thus improving the dissolving / cleaning effect of acids and alkalis on the metal ions or fine metal particles.

[0046] That is, as a post-treatment of cleaning with the fluorinated cleaning agent according to the present invention, cleaning with acid or alkali can reduce fluorinated substances and fluorinated substance aggregates, and allow the obtaining of resin pellets with reduced metal ions or metal particles, as well as fluoropolymer molded products including pellets in which both fluorinated substances and metal ions or fine metal particles are reduced.

[0047] In this invention, the fluorinated extractant used to dissolve and extract the fluorinated substance contained in or adhered to the resin pellets can be selected from various fluorinated solvents, as long as the fluorinated substance contained in or adhered to the resin pellets is soluble. Examples of such fluorinated extractants include at least one fluorinated extractant selected from hydrofluorocarbons, perfluorocarbons, fluorinated ethers, and other substances. The fluorinated extractant used to measure the evaporation residue preferably does not leave any impurity components (intentionally added components) contained in the fluorinated extractant in the evaporation residue. Even if the solvent dissolves the fluorinated substance, it is not preferred if the impurity components contained in the fluorinated extractant are retained as evaporation residues, for example, in the case of propylene glycol methyl ether acetate (PGMEA), the impurity components (antioxidants) added to PGMEA are retained as evaporation residues.

[0048] From the perspective of the purity of the evaporation residue, the fluorinated extractant used to measure the evaporation residue on the resin pellets of the present invention is preferably decafluoropentane, such as 1,1,1,2,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,4,5,5-decafluoropentane, 1,1,2,3,3,4,4,5,5,5-decafluoropentane, 1, 1,2,2,3,4,4,5,5,5-decafluoropentane, 1,1,2,2,3,3,4,4,5,5-decafluoropentane, 1,2,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,1,3,3,4,4,5,5,5-decafluoropentane, or 1,1,1,2,2,4,4,5,5,5-decafluoropentane, and more preferably 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0049] The fluorinated extractant can be appropriately selected according to the type of fluorinated substance to be dissolved, and preferably does not dissolve the resin pellets themselves. The fluorinated extractant preferably has a large boiling point difference compared to the fluorinated substance, and the boiling point difference is preferably 10°C or greater. That is, as mentioned above, the fluorinated substance contained in or adhered to the resin pellets begins to decompose at about 150°C, so that when the boiling point of the fluorinated extractant approaches 150°C, the fluorinated substance begins to decompose, which reduces evaporation residues on the fluorinated substance and makes quantitative analysis difficult. Specifically, the fluorinated extractant is preferably a gas or liquid at room temperature (20°C to 30°C), and preferably has a boiling point that does not damage the molecular structure of the fluorinated substance, and the boiling point is 0°C to 120°C, preferably 0°C to 70°C, and more preferably 20°C to 70°C. Furthermore, from an operability perspective, the boiling point is preferably at least 20°C higher than room temperature (20°C to 30°C).

[0050] When measuring evaporation residue, it is preferable to immerse the resin pellets in a fluorinated extractant such that the mixing ratio of the resin pellets to the fluorinated extractant (fluorinated extractant / resin pellets) is 2.0 to 2.5 by weight.

[0051] When resin pellets are immersed in a fluorinated extractant, they are allowed to stand at 60±2°C for 20 hours. The resin pellets are then separated from the fluorinated extractant (extract) from which the fluorinated substances have been extracted. The extract is then evaporated and dried. It is preferable to use an evaporator for evaporation and drying, and it is even more preferable to use an electronic balance for quantifying the evaporation residue.

[0052] The size and number of nanoscale particles (exotic particles) can be measured using, for example, a particle counter (immersion particle counter), wafer surface inspection equipment, or total reflection X-ray fluorescence (TXRF).

[0053] The evaporation residue on the resin pellets of the present invention can be quantified because a very small amount of fluorine-containing material is concentrated through the evaporation and drying steps. Therefore, it is possible to determine whether the resin pellets contain fluorine-containing material or whether fluorine-containing material adheres to the resin pellets. This fluorine-containing material adheres to the wafer surface during semiconductor manufacturing processes and becomes the cause of nanoscale particles (contaminating fine particles) that form defects in the circuit patterns of fine semiconductor devices, and the residual amount of fluorine-containing material on the wafer can be predicted.

[0054] pellet form

[0055] The resin pellets of the present invention comprise a resin containing at least one selected from tetrafluoroethylene homopolymers and copolymers, and are used as molding materials, wherein the resin is processed into pellets (pellets) to improve workability.

[0056] The average particle size of the resin pellets is not limited to this, but is preferably 0.4 mm to 5.0 mm. Examples of resin pellets within the above-mentioned average particle size range include pellets with an average particle size of 0.4 mm to less than 1 mm (referred to as small pellets) and pellets with an average particle size of 1.0 mm to 5.0 mm. Depending on the intended use, pellets with a suitable average particle size can be suitably used as molding materials.

[0057] TFE homopolymer

[0058] The tetrafluoroethylene homopolymer constituting the resin pellets of the present invention may be: PTFE, which is a homopolymer of tetrafluoroethylene (TFE); modified PTFE, which does not have thermal melting properties and is modified with at least one monomer that can copolymerize with tetrafluoroethylene (TFE) to a extent that does not impair the characteristics of PTFE; or a mixture of PTFE and at least one modified PTFE. Examples of monomers for modified PTFE include ethylene, propylene, isobutylene, vinyl chloride, dichloroethylene, vinyl fluoride, difluoroethylene, perfluorobutylethylene (3,3,4,4,5,5,5,6,6,6-nonafluoro-1-hexene), trifluorochloroethylene, perfluoroolefins having three or more carbon atoms, and perfluoro(alkyl vinyl ethers).

[0059] Examples of modified PTFE as copolymers of TFE with small amounts of monomers other than TFE are described in WO2007 / 119829, and specific examples include copolymers of tetrafluoroethylene with 0.005 mol% to 1 mol%, preferably 0.01 mol% to 0.1 mol%, and more preferably 0.01 mol% to 0.05 mol% of at least one monomer selected from hexafluoropropylene, perfluoro(alkyl vinyl ether), fluoroalkyl vinylidene, trichlorofluoroethylene, vinylidene fluoride, vinyl fluoride, and ethylene, wherein the copolymer does not have melt-molding properties. Fluorinated monomers are preferred, and more preferably perfluoroolefins having 3 to 6 carbon atoms and perfluoro(alkyl vinyl ether) having 1 to 6 carbon atoms.

[0060] Tetrafluoroethylene homopolymers can be produced by known methods such as solution polymerization, emulsion polymerization, and suspension polymerization.

[0061] TFE copolymer

[0062] The tetrafluoroethylene copolymer constituting the resin pellets of the present invention is a copolymer of tetrafluoroethylene (TFE) and 1 mol% or more of monomers that can copolymerize with tetrafluoroethylene (TFE). The tetrafluoroethylene copolymer is a copolymer that melts at a temperature equal to or above its melting point and exhibits melt flowability (thermal meltability), or a composition comprising copolymers, and examples include copolymers of unsaturated fluorinated hydrocarbons, unsaturated fluorinated chlorinated hydrocarbons, and ether-containing unsaturated fluorinated hydrocarbons, as well as thermally meltable fluoropolymers, such as copolymers of these unsaturated fluorinated hydrocarbons and ethylene.

[0063] Examples include copolymers comprising tetrafluoroethylene with at least one comonomer, such as copolymers with at least one monomer selected from perfluoroolefins having 3 or more carbon atoms and fluoroalkoxytrifluoroethylene (preferably perfluoro(alkyl vinyl ether)) (PAVE) (the alkyl group being a straight-chain or branched alkyl group having 1 to 5 carbon atoms), or copolymers of any of these monomers with ethylene.

[0064] Examples of preferred copolymers include TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxane copolymer, TFE / CF2=CFOCF2CF(CF3)OCF2CF2SO2F copolymer, and mixtures of these copolymers. More preferred examples include at least one copolymer selected from TFE / perfluoro(methyl vinyl ether) (PMVE), TFE / perfluoro(ethyl vinyl ether) (PEVE), TFE / perfluoro(propyl vinyl ether) (PPVE), and TFE / perfluoro(butenyl vinyl ether).

[0065] The amount of PAVE in the copolymer is preferably from 1 mol% to 30 mol%, and more preferably from 1 mol% to 20 mol%. Additionally, the amount of hexafluoropropylene in the FEP is preferably from 1 mol% to 10 mol%.

[0066] In addition, to suppress the generation of pyrolysis products, copolymers with minimal impurity elution can be prepared by converting (fluorinating) unstable end groups such as -CF2CH2OH, -CONH2, or -COF to thermally stable -CF3 end groups.

[0067] The tetrafluoroethylene copolymer is preferably a copolymer having a melt flow rate (MFR) of about 1 g / 10 min to 100 g / 10 min at 372°C according to ASTM D-1238. The melt flow rate (MFR) can be selected according to the molding method. For example, in melt molding such as melt extrusion molding or injection molding, the melt flow rate is 1 g / 10 min to 100 g / 10 min, preferably 1 g / 10 min to 50 g / 10 min, and more preferably 1 g / 10 min to 20 g / 10 min.

[0068] Tetrafluoroethylene copolymers can be used alone or as mixtures of two or more of these copolymers. Other examples include mixtures of at least two or more copolymers of the same type that differ in, for example, monomer type, monomer content, molecular weight (weight-average molecular weight or number-average molecular weight), molecular weight distribution, melting point and melt flow rate (MFR), or mechanical properties. Examples include PFA mixtures and FEP mixtures.

[0069] Tetrafluoroethylene copolymers can be produced by known methods such as solution polymerization, emulsion polymerization, or suspension polymerization.

[0070] The melting point of the tetrafluoroethylene copolymer is not limited, but is preferably 150°C or higher, and more preferably 150°C to 340°C.

[0071] The resin containing at least one of the tetrafluoroethylene homopolymers and copolymers selected from the present invention can be a mixture of the above-mentioned tetrafluoroethylene polymers that do not have melt-molding properties and tetrafluoroethylene copolymers that have melt-molding properties.

[0072] Method for producing resin pellets

[0073] The resin pellets of the present invention can be produced by molding at least one resin selected from the above-mentioned tetrafluoroethylene homopolymers and copolymers into pellets and then cleaning them with a fluorinated cleaning agent.

[0074] There are no specific limitations on the molding method used to obtain resin pellets, and known methods can be used. For example, pellets can be obtained by melt kneading and extrusion using a single-screw extruder, a twin-screw extruder, or a tandem extruder, and then cut to a predetermined length by melt cutting or strand cutting.

[0075] As described above, the average particle size of the resin pellets is preferably in the range of 0.4 mm to 5.0 mm.

[0076] In the resin pellets of the present invention, by cleaning the obtained resin pellets with a fluorinated cleaning agent, the amount of fluorinated substances contained in or adhering to the resin pellets can be reduced, so that the aforementioned evaporation residues are as close to zero as possible.

[0077] Resin pellets are cleaned by contacting them with a fluorinated cleaning agent. Examples of this method include immersing the resin pellets in the fluorinated cleaning agent (and stirring them in the fluorinated cleaning agent), and flowing the fluorinated cleaning agent over the surface of the resin pellets (circulating the fluorinated cleaning agent of the present invention using a pump or the like).

[0078] From an economic point of view, the cleaning process is preferably carried out at a temperature between room temperature and a saturated vapor pressure of about 70 kPa, or at a temperature about 10°C lower than the boiling point of the fluorinated solvent used.

[0079] The mixing ratio of fluorinated cleaning agent to resin pellets (fluorinated cleaning agent / resin pellet (weight ratio)) for cleaning treatment is not limited, but is preferably 0.01 or greater, and more preferably 0.1 or greater.

[0080] Fluorinated cleaning agents used for cleaning resin pellets are solvents used to dissolve substances (fluorinated substances) that cause nanoscale particles contained in or adhered to resin pellets, and include fluorinated solvents. The fluorinated cleaning agent is preferably selected from at least one of hydrofluorocarbons, perfluorocarbons, and fluorinated ethers.

[0081] Hydrofluorocarbons are saturated or unsaturated compounds containing only carbon, fluorine, and hydrogen atoms and having a carbon number of 3 to 9, preferably 4 to 8, wherein at least 50% of all atoms bonded to the carbon atoms are fluorine atoms. Examples include: saturated hydrocarbons such as tridecafluorooctane, pentadecadecafluoroheptane, decafluoropentane, pentafluorobutane, pentafluoropropane, and heptafluorocyclopentane; and unsaturated hydrocarbons such as hydrofluoroolefins (HFOs) represented by the following general formula (I): R f -CH2CH=CHCH2-Rf(I) (where Rf is a perfluoroalkyl group).

[0082] By C5H2F 10 The decafluoropentane represented is preferably used as a saturated hydrocarbon. Many structural isomers of decafluoropentane exist, but mixtures thereof can be used. More preferably is 1,1,1,2,3,4,4,5,5,5-decafluoropentane or a mixture of 1,1,1,2,3,4,4,5,5,5-decafluoropentane with another decafluoropentane isomer.

[0083] The unsaturated hydrocarbon is preferably 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), its isomers, 1,1,1,4,4,4-hexafluoro-2-butene, its isomers, or mixtures of isomers. 1,1,1,4,4,4-hexafluoro-2-butene is more preferably (Z)-HFO-1336mzzm.

[0084] Perfluorocarbons are saturated or unsaturated compounds containing only carbon and fluorine atoms and having a carbon number of 1 to 9, and examples include: fully fluorinated cycloalkanes, such as tetrafluoromethane, hexafluoroethane, octafluoropropane, decafluorobutane, dodecafluoropentane, tetradecylfluorohexane, octafluorocyclobutane, and perfluoromethylcyclohexane; and unsaturated hydrocarbons, such as perfluoroolefins represented by the following general formula (II): CF2=CFR f ...(II) (where Rf is a perfluoroalkyl group).

[0085] Several isomers of perfluoroheptene exist, such as perfluoro-2-heptene and perfluoro-3-heptene, and these isomers can be used alone or in combination.

[0086] Fluorinated ethers are ethers containing fluorine, and examples include hydrofluoroethers (HFE) and perfluoroethers (PFE).

[0087] Examples of hydrofluoroethers (HFEs) include saturated or unsaturated compounds having an ether bond, and examples include hexafluoroisopropanol, trifluoroethanol, tetrafluoroethanol, pentafluoropropanol, 1,1,1-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, nonafluorobutyl methyl ether, and alkoxy-perfluoroolefins. Preferred are HFEs having 3 to 8 carbon atoms, and examples include Novec manufactured by 3M Japan Ltd. TM 7200, Novec TM 7500 and Novec TM 7600.

[0088] Examples of perfluoroethers (PFEs) include perfluoro(alkyl)alkyl ethers, such as perfluoro(propyl)methyl ether, perfluoro(butyl)methyl ether, perfluoro(hexyl)methyl ether and perfluoro(butyl)ethyl ether.

[0089] Examples of alkoxy-perfluoroolefins include methoxy-perfluoroolefins and ethoxy-perfluoroolefins having 5 to 10 carbon atoms, and preferred examples include methoxy-perfluoropentene, methoxy-perfluorohexene, methoxy-perfluoroheptene, methoxy-perfluorooctene, ethoxy-perfluoropentene, ethoxy-perfluorohexene, ethoxy-perfluoroheptene, ethoxy-perfluorooctene, and mixtures thereof. Note that various structural isomers of alkoxy-perfluoroolefins exist; however, their structures are not particularly limited. Mixtures thereof may be used, and structures suitably chosen for the purposes of this invention may be selected.

[0090] More preferred examples include methoxyperfluoroheptene, its isomers, and mixtures thereof. The following are examples of the structure of methoxyperfluoroheptene, but any structure may be used.

[0091] (1)CF3(CF2)2CF=CFCF(OCH3)CF3

[0092] (2)CF3CF2CF=CF(CF2)2(OCH3)CF3

[0093] (3)CF3CF2CF=CFCF(OCH3)CF2CF3

[0094] (4)CF3CF=CFCF(OCH3)(CF2)2CF3

[0095] (5)CF3CF=CFCF2CF(OCH3)CF2CF3

[0096] (6)CF3CF2CF=C(OCH3)(CF2)2CF3

[0097] (7)CF3CF2C(OCH3)=CFCF2CF2CF3

[0098] Preferred examples of perfluoroheptenes include Opteon manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd. TM SF10.

[0099] Similar to the aforementioned fluorinated extractants, fluorinated cleaning agents can be appropriately selected based on the type of fluorinated substance to be dissolved. The boiling point difference between the fluorinated extractant and the fluorinated substance is preferably large, and more preferably 10°C or higher. That is, as described above, fluorinated substances contained in or adhered to resin pellets begin to decompose at approximately 150°C. This means that when the boiling point of the fluorinated extractant approaches 150°C, the fluorinated substance begins to decompose, reducing the evaporation residue and making quantitative analysis difficult. Specifically, the fluorinated cleaning extractant is preferably a gas or liquid at room temperature (20°C to 30°C), and preferably has a boiling point that does not damage the molecular structure of the fluorinated substance, with a boiling point of 0°C to 120°C, preferably 0°C to 70°C, and more preferably 20°C to 70°C. Furthermore, from an operability perspective, the boiling point is preferably at least 20°C higher than room temperature (20°C to 30°C).

[0100] Furthermore, the fluorinated cleaning agent used for cleaning resin pellets preferably does not leave any impurity components (intentionally added components) of the fluorinated cleaning agent on the resin pellets. Similar to the fluorinated extractant used to measure the aforementioned evaporation residue, the cleaning agent is preferably decafluoropentane, such as 1,1,1,2,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,4,5,5-decafluoropentane, 1,1,2 ... 4,5,5,5-decafluoropentane, 1,1,2,2,3,3,4,4,5,5-decafluoropentane, 1,2,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,1,3,3,4,4,5,5,5-decafluoropentane, or 1,1,1,2,2,4,4,5,5,5-decafluoropentane, and more preferably 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0101] The resin pellets, cleaned with a fluorinated cleaning agent, are separated from the cleaning agent and dried at 270±5°C for 20 hours, followed by cooling in an oven to obtain the resin pellets of the present invention. Since the melt flow rate of the cleaned resin pellets is the same as that of the uncleaned resin pellets, they can be used without changing the molding conditions of the molded products.

[0102] In this invention, as a post-treatment following cleaning with the aforementioned fluorinated cleaning agent, as described above, cleaning with an acid or alkali may be added. This allows for the production of resin pellets in which not only fluorinated substances and their aggregates are reduced, but also metal ions or fine metal particles are reduced.

[0103] Molded products

[0104] The molded product of the present invention is a molded product comprising the resin pellets of the present invention described above, and preferably wherein the evaporation residue after evaporation and drying of the extract obtained by dissolving and extracting the fluorinated substances contained in or adhering to the molded product in a fluorinated extractant is 20 × 10⁻⁶. -6 mg / mm 2 Or fewer molded products.

[0105] Even in molded products, evaporation residues are preferably as close to zero as possible, and preferably within 20 × 10⁻⁶. -6 mg / mm 2 Or within a smaller range, preferably from 0 to 10 × 10 -6 mg / mm 2 Within the range, and more preferably within 0 to 1.0 × 10 -6 mg / mm 2Within this range, in the molded products of the present invention where the evaporation residue is within this range, the generation of substances (fluorine-containing substances) that cause particulate formation is suppressed, making the molded product suitable as a high-cleanliness molded product for use in semiconductor manufacturing.

[0106] Measurement of the evaporation residue of fluorinated substances contained in or adhered to the molded product can be performed in the same manner as the resin pellets described above; however, depending on the shape of the molded product, it is preferable to bring the surface of the molded product into contact with the fluorinated extractant. For example, in molded products with hollow portions (such as tubes or bottles), the extract can be collected by filling the tube or bottle with the fluorinated extractant.

[0107] The molded products of the present invention are preferably molded products for liquid transfer, liquid contact, etc. Specifically, molded products for liquid transfer are products used in liquid transfer devices, such as pipes, pipe fittings, gaskets, O-rings, pumps, valves, regulators, and filter housings; and molded products for liquid contact are products used in tools and devices that come into contact with liquids other than those used for liquid transfer, such as containers, such as transport containers and storage containers (e.g., bottles, caps, and inner caps), wafer carriers, and membranes.

[0108] The molded product of the present invention is preferably a molded product having a hollow portion. Examples of molded products having this hollow portion include bottles, tubes, pipes, and pipe fittings.

[0109] There are no specific limitations on the method used to mold the molded products of the present invention, and the molded products of the present invention can be molded by known molding methods using the resin pellets of the present invention. Examples of molding methods include compression molding, paste extrusion molding, melt compression molding, melt extrusion molding, injection molding, transfer molding, blow molding, rotational molding, liner molding, and film molding.

[0110] Since the molded articles of the present invention are molded using the resin pellets of the present invention, the aforementioned evaporation residue can be reduced to 20 × 10⁻⁶. -6 mg / mm 2 Or less, however, the molded articles can be further cleaned using the aforementioned fluorinated cleaning agents. This further improves the cleanliness of the molded articles.

[0111] Examples of cleaning processes include methods similar to the resin pellet cleaning process described above, such as contacting the molded article with a fluorinated cleaning agent, immersing it in the molded article (and stirring it in the molded article), and shaking the molded article, as well as methods for allowing the fluorinated cleaning agent to flow on the surface of the molded article (using a pump or the like to circulate the fluorinated cleaning agent).

[0112] The cleaning conditions can be the same as those for the cleaning of the resin pellets described above.

[0113] In addition, as a post-treatment for cleaning with the fluorinated cleaning agent according to the present invention, cleaning with acid or alkali can reduce the fluorinated substances that protect metal ions or metal particles, and allows the obtaining of resin pellets with reduced metal ions or metal particles, as well as fluoropolymer molded products including pellets in which both fluorinated substances and metal ions or metal particles are reduced.

[0114] When the fluorinated cleaning agent used in this invention is capable of dissolving and extracting deposits or inclusions in resin pellets or molded articles, in addition to the aforementioned resin pellets made from at least one of tetrafluoroethylene homopolymers or copolymers or molded articles comprising such resin pellets, the cleaning agent may also be used for resin pellets made from engineering plastics, such as resin pellets made from polyethylene, polypropylene, vinyl chloride, phenolic resin or silicone resin, and molded articles comprising such pellets.

[0115] Example

[0116] The invention will be described in further detail below using examples, but the invention is not limited to these examples.

[0117] The materials, cleaning processes, and measurement methods used in the examples are as follows.

[0118] Material

[0119] 1. Resin pellets

[0120] (1) PFA pellets (1)

[0121] (MFR: 2g / 10min, melting point 310℃)

[0122] (2) PFA pellets (2)

[0123] (MFR: 5g / 10min, melting point 263℃)

[0124] 2. Fluorine-containing extractant

[0125] (1) 1,1,1,2,3,4,4,5,5,5-decafluoropentane (boiling point 55℃) (represented by "XF" in the table)

[0126] 3. Fluoride-containing cleaning agents

[0127] (1) Methoxyperfluoroheptene (boiling point 110℃) (represented by "SF10" in the table)

[0128] (2) Perfluoroheptene (boiling point 72℃) (represented by "PFH" in the table)

[0129] (3) 1,1,1,2,3,4,4,5,5,5-decafluoropentane (boiling point 55℃) (represented by "XF" in the table)

[0130] 4. Molded products containing resin pellets

[0131] (1) pipe

[0132] Using the resin pellets shown in Table 1, heat the resin pellets to a temperature equal to or above the melting point and extrude them to obtain an unstretched tube with an outer diameter of 6.35 mm, an inner diameter of 4.35 mm, and a length of 50 m.

[0133] (2 bottles)

[0134] Using the resin pellets shown in Table 1, heat the resin pellets to a temperature equal to or above their melting point, and obtain 100ml bottles by blow molding.

[0135] 5. Cleaning treatment

[0136] (1) Cleaning treatment of resin pellets

[0137] The mixture of fluorinated detergent and resin pellets, prepared at the weight ratio (fluorinated detergent / resin pellets) shown in Table 1 or Table 3, was heated in an oven at the cleaning temperature shown in Table 1 or Table 3 for 2 hours. The resin pellets and fluorinated detergent were then separated. The separated resin pellets were dried at the drying temperature shown in Table 1 or Table 3 for 20 hours, and then cooled in an oven until the temperature reached room temperature (20°C to 30°C).

[0138] (2) Cleaning of molded products (tubes)

[0139] The fluorinated cleaning agent shown in Table 2 was sealed in a 50m unstretched tube by folding both ends 100mm with a plastic strip and left to stand in an oven at 60°C for 20 hours. Afterward, the tube was dried at room temperature (20°C to 30°C) for 5 to 10 minutes using nitrogen gas passed through a 0.003μM in-line filter.

[0140] (3) Cleaning of molded products (bottles)

[0141] Seal 130g of the fluorinated cleaning agent shown in Table 2 into a 100ml bottle using a cleaned PFA cap and allow it to stand at room temperature for 168 hours. After that, drain the fluorinated cleaning agent and dry the bottle at room temperature (20°C to 30°C) for 24 hours or longer in a cleanroom with a cleanliness level of 100 or lower.

[0142] Measurement methods

[0143] 6. Measurement of evaporation residue

[0144] (1) The evaporation residue (raw material) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was placed in a round-bottom flask (300 ml) with 500 g or 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) and evaporated and dried using an evaporator (evaporated to dryness). Each evaporation residue was weighed using an electronic balance, and the amount (mg) of the evaporation residue of 1,1,1,2,3,4,4,5,5,5-decafluoropentane was determined.

[0145] (2) Evaporation residue on resin pellets

[0146] The resin pellets were immersed in 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) and allowed to stand at 60°C for 20 hours. Then, the 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was filtered through a 0.2 μm polypropylene filter membrane to remove fine PFA powder contained in or adhering to the resin pellets, and the filtrate was used as the extractant. 500 g of the extractant was evaporated and dried using an evaporator, and the evaporation residue was weighed using an electronic balance. The amount of evaporation residue in the 500 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane described in (1) above was subtracted from this amount to obtain the surface area per pellet of the evaporation residue (mg / mm²). 2 The surface area of ​​the pellets is calculated according to SEMI C90-1015.

[0147] (3) Evaporation residue on molded products (unstretched tubes)

[0148] 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was sealed in a 50m molded product (unstretched tube) by folding both ends of the tube 100mm with plastic tape, and placed at 60°C for 20 hours. Nitrogen extraction was then used to prepare the extractant. 500g of the extractant was evaporated and dried using an evaporator, and the evaporation residue was weighed using an electronic balance. The amount of evaporation residue from the 500g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane in (1) above was subtracted from this amount to obtain the inner surface area (mg / mm²) of the evaporation residue per unstretched tube. 2 ).

[0149] (4) Evaporation residue on molded products (bottles)

[0150] 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was sealed in a 100 ml bottle and allowed to stand at room temperature for 168 hours before being used as an extractant. The 130 g extractant was evaporated and dried using an evaporator, and the evaporation residue was weighed using an electronic balance. The amount of evaporation residue from the 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane described in (1) above was subtracted from this amount to obtain the internal surface area (mg / mm²) of the evaporation residue per bottle. 2 ).

[0151] 7. Melt Flow Rate (MFR)

[0152] Using a melt indexer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) equipped with a corrosion-resistant gas cylinder, die, and piston conforming to ASTM D-1238-95, 5g of sample powder was filled into a cylinder at 372±1°C and held for 5 minutes. Then, it was extruded through a die orifice under a 5kg load (piston and weights). The extrusion rate (g / 10 minutes) at this point was determined as the MFR.

[0153] Examples 1 to 6

[0154] After cleaning using the resin pellets and conditions shown in Table 1, the evaporation residue on the resin pellets was determined. The results are shown in Table 1.

[0155] Comparative Example 1

[0156] The evaporation residues of the resin pellets shown in Table 1 were determined in the same manner as in Example 1, except that no cleaning treatment was performed. The results are shown in Table 1.

[0157] Examples 7 to 10

[0158] The evaporation residue on molded products (tubes) of the resin pellets from Examples 1, 3, 4, and 6 shown in Table 2 was determined. The results are shown in Table 2.

[0159] Examples 11 to 14

[0160] After cleaning the molded products (tubes) containing the resin pellets of Examples 1, 3, 4 and 6 shown in Table 2, the evaporation residue on the molded products (tubes) was determined. The results are shown in Table 2.

[0161] Example 15

[0162] After cleaning the molded product (bottle) including the resin pellets of Example 3 shown in Table 2, the evaporation residue on the molded product (bottle) was determined. The results are shown in Table 2.

[0163] Comparative Example 2

[0164] The evaporation residue on the molded product (tube) including the pellets of Comparative Example 1 was determined in the same manner as in Example 7, except that the resin pellets of Comparative Example 1 were used. The results are shown in Table 2.

[0165] Comparative Example 3

[0166] The evaporation residue on the molded product (tube) including the pellets of Comparative Example 1 was determined in the same manner as in Example 11, except that the resin pellets of Comparative Example 1 were used. The results are shown in Table 2.

[0167] Comparative Example 4

[0168] The evaporation residue on molded products (bottles) including the pellets of Comparative Example 1 was determined. The results are shown in Table 2.

[0169] Comparative Example 5

[0170] The evaporation residue on the molded product (bottle) including the pellets of Comparative Example 1 was determined in the same manner as in Example 15, except that the resin pellets of Comparative Example 1 were used. The results are shown in Table 2.

[0171] Examples 16 to 17

[0172] After cleaning using the resin pellets and conditions shown in Table 3, the evaporation residue on the resin pellets was determined. The results are shown in Table 3.

[0173] Comparative Example 6

[0174] The evaporation residue on the resin pellets was determined in the same manner as in Example 16, except that no cleaning treatment was performed. The results are shown in Table 3.

[0175] Table 1

[0176]

[0177] [Table 2]

[0178]

[0179] [Table 3]

[0180]

[0181] Industrial applicability

[0182] The resin pellets of the present invention are suitable as molding materials for molding products used in semiconductor manufacturing that require high cleanliness. Furthermore, the molding products of the present invention are suitable as molding products with high cleanliness used in semiconductor manufacturing for liquid transfer or liquid contact.

Claims

1. A resin pellet comprising at least one selected from tetrafluoroethylene homopolymers or copolymers and having an evaporation residue, wherein the resin pellet has been washed with a fluorinated cleaning agent, wherein the fluorinated cleaning agent comprises an unsaturated perfluoroolefin and / or an alkoxyperfluoroolefin with a boiling point difference of 10°C or higher from the fluorinated material contained in and / or adhered to the pellet, wherein the evaporation residue is determined by evaporation and drying of an extract, wherein the extract is prepared by dissolving and extracting the fluorinated material contained in or adhered to the washed resin pellet in a fluorinated extractant and filtering the extract through a polypropylene filter membrane having a pore size of 0.2 µm, and wherein the evaporation residue is in the range of 0 to 1.0 × 10⁻⁶. -6 mg / mm 2 Within the range.

2. The resin pellets according to claim 1, wherein the tetrafluoroethylene (TFE) copolymer is at least one of the following: TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxane-pentene copolymer, TFE / CF2=CFOCF2CF(CF3)OCF2CF2SO2F copolymer, or a mixture of these copolymers.

3. The resin pellets according to claim 1, wherein the fluorinated extractant is decafluoropentane.

4. A method for producing resin pellets according to claim 1, the method comprising cleaning resin pellets comprising at least one selected from tetrafluoroethylene homopolymers or copolymers with a fluorinated cleaning agent at a temperature about 10°C lower than the boiling point of the fluorinated cleaning agent at a mixing ratio of 0.1 or greater of the fluorinated cleaning agent to the resin pellets.

5. The method for producing resin pellets according to claim 4, wherein the cleaning with the fluorinated cleaning agent is followed by cleaning with an acidic or alkaline solution.

6. A molded product comprising resin pellets according to claim 1.

7. The molded product according to claim 6, wherein the evaporation residue after evaporation and drying, following the extraction of the extract obtained by dissolving and extracting the fluorinated substance contained in or adhering to the molded product in a fluorinated extractant, is 20 × 10⁻⁶. -6 mg / mm 2 Or less.

8. The molded product according to claim 6, wherein the molded product has a hollow portion.

9. The molded product according to claim 6, wherein the molded product has been cleaned with a fluorinated cleaner, or has been cleaned with a fluorinated cleaner and then cleaned with an acidic or alkaline solution.

10. The molded product according to claim 9, wherein the fluorinated cleaning agent for cleaning the molded product is selected from at least one of hydrofluorocarbons, perfluorocarbons, and fluorinated ethers.

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