Solvent for gas chromatography-mass spectrometry and method for determining fluorine-containing substances on the surface of a fluororesin melt-molded product

Abstract

The present invention provides a fluorinated solvent for gas chromatography - mass spectrometry of fluorine - containing substances, which are found to contaminate the surface of fluororesin melt - molded products and are disadvantageous for the use of such products in fluid handling in semiconductor manufacturing. The present invention also provides a method for quantitative determination of such fluorine - containing substances and a method for qualitative analysis of such fluorine - containing substances, which are based on a gas chromatography - mass spectrometry method using the fluorinated solvent, enabling the determination of the presence or absence of trace contaminant fluorine - containing substances present as fine particles on the surface of melt - molded fluororesin products.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Japanese Patent Application JP 2019 - 040040 filed on March 5, 2019, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present invention relates to a solvent for gas chromatography - mass spectrometry (GC - MS) of fluorine - containing substances, the solvent comprising a fluorine - containing solvent; a method for quantitatively determining fluorine - containing substances that contaminate the surface of a fluororesin melt - molded product; and a method for qualitatively analyzing such fluorine - containing substances, these methods being based on a gas chromatography - mass spectrometry method using the fluorine - containing solvent for gas chromatography - mass spectrometry. Background art

[0004] Fluororesins have excellent heat resistance and chemical resistance and can be obtained in the form of a fine - particle dispersion of fluororesin by emulsion polymerization or suspension polymerization. The fine particles in the aqueous dispersion of fluororesin can be dried or further granulated and dried to form a fluororesin powder for molding (fine powder or molding powder), or the fluororesin powder for molding can be further melt - molded to form a molding material in the form of beads or pellets. Various fluororesin molded products can be produced from such beads or pellets by known molding methods such as extrusion molding, injection molding, transfer molding, rotational molding, blow molding, and compression molding.

[0005] Various fluororesin molded products utilizing the characteristics of fluororesins are also used in the production of semiconductor devices. As the circuit patterns of semiconductor devices become finer and denser due to high integration and multi - layer wiring, the size of surface contaminants that can cause defects or failures in semiconductor devices also becomes smaller. Therefore, since the materials or processes used in the production of semiconductor devices have an increasingly significant impact on the yield and reliability of semiconductor products, their cleaning has become increasingly critical (see "New Edition Silicon Wafer Surface Cleaning Technology" by Takeshi Hattori, Realize Corporation, published in 2000).

[0006] The surface of a fluororesin molded product for semiconductor production is usually cleaned with a diluted aqueous solution of a surfactant, strong acid, ultrapure water, etc. to remove fine particles, such as nanoparticles (contaminant fine particles). However, with these methods, the cleaning time is undesirably long, and processing methods such as those proposed in Japanese Patent Application Laid-Open H08-005140 cannot be achieved by simple means because the method requires special equipment. Moreover, it is not easy to remove such contaminant particles from the surface of the fluororesin molded product, and it is difficult to achieve a cleanliness level that meets the requirements of the fluororesin molded product used in semiconductor production.

[0007] When fine particles, such as nanoparticles (contaminant fine particles), adhere to the surface of a fluororesin molded product - specifically, for its liquid contact portion - the particles can be carried by chemical liquids used in semiconductor production equipment and undesirably deposited on the surface of a semiconductor wafer, which can cause defects in the fine semiconductor device circuit pattern and potential failure of the semiconductor device. There are many causative substances of nanoparticles (contaminant fine particles) that cause defects in the semiconductor device circuit pattern, and it is not limited to a single type. However, fluorine-containing deposits (fluorine-containing substances) adhering to the liquid contact portion of the surface of the fluororesin molded product can be regarded as one of the causative substances. Such causative substances (fluorine-containing substances) are considered to form when unstable end groups of the fluororesin chain or the fluororesin itself pyrolyze in the molten state and generate fluorine-containing gaseous degradation products of the fluororesin, which then condense as fluorine-containing contaminant fine particle deposits on the surface of the fluororesin melt molded product (for example, when it cools and solidifies after melt molding).

[0008] In addition, a fluorine-containing substance, which is one of the causative substances of fine particles such as nanoparticles, has such properties that, in addition to the very small amount of adhesion per unit area, the substance generally also exhibits high resistance to organic solvents and is difficult to dissolve in organic solvents. Since the fluorine-containing substance does not dissolve in ultrapure water or ammonia-diluted solution that is usually used to clean the pipes of semiconductor production equipment or the extraction solvent (for example, acetone) that is usually used in gas chromatography-mass spectrometry (GC-MS) analysis, there is no identified appropriate solvent in this field, and it is difficult to analyze the presence or absence of the fluorine-containing substance or the substance itself. Summary of the Invention

[0009] In view of the above situation, an object of the present invention is to provide a solvent for gas chromatography - mass spectrometry (GC - MS) of fluorine - containing substances, the solvent including a fluorine - containing solvent; a method for quantitatively determining fluorine - containing substances that contaminate the surface of a melt - molded fluororesin product; and a qualitative analysis method, these methods being based on a GC - MS method using the solvent for gas chromatography - mass spectrometry, so as to be able to determine the presence or absence of causative substances (fluorine - containing substances) of trace - level nanoparticles (contaminant fine particles) in a melt - molded fluororesin product.

[0010] The present invention provides a solvent for gas chromatography - mass spectrometry (GC - MS) of fluorine - containing substances, the solvent including a fluorine - containing solvent; a method for quantitatively determining fluorine - containing substances that contaminate the surface of a melt - molded fluororesin product; and a qualitative analysis method, these methods being based on a GC - MS method using a fluorine - containing solvent.

[0011] In some embodiments of the present invention, the above - mentioned fluorine - containing solvent for mass spectrometry is at least one type selected from hydrofluorocarbons, perfluorocarbons, fluorinated ethers, and fluorinated alcohols.

[0012] In one embodiment, the above - mentioned fluorine - containing solvent for mass spectrometry is a fluorine - containing solvent having a standard boiling point of 0 °C to 70 °C.

[0013] In one embodiment, the above - mentioned fluorine - containing solvent for mass spectrometry is a fluorine - containing solvent having a standard boiling point of 20 °C to 70 °C.

[0014] In one embodiment of the present invention, the above - mentioned fluorine - containing solvent for mass spectrometry is decafluoropentane.

[0015] In one embodiment of the present invention, the above - mentioned fluorine - containing solvent for mass spectrometry is 1,1,1,2,3,4,4,5,5,5 - decafluoropentane.

[0016] In one embodiment, the fluorine - containing substance is a fluorine - containing substance attached to the surface of a melt - molded fluororesin product.

[0017] In one embodiment, the present invention is a method for quantitatively determining fluorine - containing substances that contaminate the surface of a melt - molded fluororesin product, the method including: dissolving and extracting the fluorine - containing substance on the surface of the melt - molded fluororesin product to form an extract solution; evaporating the extract solution to dryness to obtain the fluorine - containing substance as a non - volatile residue; and then determining the amount of the non - volatile residue.

[0018] In one embodiment, the present invention is a method for quantitatively determining fluorine - containing substances that contaminate the surface of a melt - molded fluororesin product, the method including: evaporating and drying an extract solution prepared by dissolving and extracting a fluorine - containing substance in the above - mentioned solvent for mass spectrometry to obtain a non - volatile residue of the extract solution; and then determining the amount of the non - volatile residue.

[0019] In one embodiment, the present invention is a method for qualitative analysis of a fluorine-containing substance that contaminates the surface of a fluororesin melt-molded product, the method comprising: using an analysis specimen quantified by dissolving a non-volatile residue obtained by the above-described quantitative determination method in the above-described solvent for mass spectrometry to obtain a total ion chromatogram (TIC) in the mass number range of 0 to 650 (or 0 to 500 in some embodiments) for a gas chromatography-mass spectrometry (GC-MS) method; and then performing qualitative analysis based on the mass-to-charge ratio (m / Z) of the MS spectrum at each peak.

[0020] In one embodiment, the present invention is a fluororesin molded product, wherein the non-volatile residue of the fluorine-containing substance quantified by the above-described quantitative determination method is 20×10 -6 mg / mm 2 or less.

[0021] With the present invention, there are provided: a solvent for gas chromatography-mass spectrometry of a fluorine-containing substance, the solvent comprising a fluorine-containing solvent; a method for quantitative determination of a fluorine-containing substance that contaminates the surface of a fluororesin melt-molded product; and a qualitative analysis method, these methods being based on a gas chromatography-mass spectrometry (GC-MS) method using a solvent for gas chromatography-mass spectrometry, and they are used for qualitatively and quantitatively analyzing trace amounts of fluorine-containing substances. The reason why the present invention can qualitatively and quantitatively analyze trace fine particles such as nanoparticles (contaminant fine particles) is the fluorine-containing substance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a graph showing the mass-to-charge ratio (m / Z) of the MS spectrum in Example 1.

[0023] Figure 2 is a graph showing the mass-to-charge ratio (m / Z) of the MS spectrum in Example 5.

[0024] Figure 3 is a graph showing the mass-to-charge ratio (m / Z) of the MS spectrum in Example 9.

[0025] Figure 4 is a graph showing the mass-to-charge ratio (m / Z) of the MS spectrum in Example 10.

[0026] Figure 5 is the total ion chromatogram (TIC) in Reference Example 1.

[0027] Figure 6 is the total ion chromatogram (TIC) in Reference Example 2.

[0028] Figure 7 is the total ion chromatogram (TIC) in Reference Example 3.

[0029] Figure 8 It is a conceptual diagram for explaining a fluorine-containing material (deposited on the outer surface of an extrusion shaping die) to be analyzed. Detailed implementation mode

[0030] The present invention provides a solvent for gas chromatography-mass spectrometry, the solvent comprising a fluorinated solvent; a method for quantitatively determining a fluorine-containing substance that contaminates the surface of a fluororesin melt-molded product; and a qualitative analysis method, these methods being based on a gas chromatography-mass spectrometry (GC-MS) method using the solvent for gas chromatography-mass spectrometry, and they are used for qualitatively and quantitatively analyzing the causative substances (fluorine-containing substances) adhering to the surface of a fluororesin melt-molded product in trace amounts.

[0031] Solvent for GC-MS analysis

[0032] The solvent for gas chromatography-mass spectrometry comprising the fluorinated solvent according to the present invention is a solvent for dissolving the causative substances (fluorine-containing substances) on the surface of a fluororesin melt-molded product, and the solvent comprises a fluorinated solvent. In one embodiment, the fluorinated solvent is at least one type selected from hydrofluorocarbons, perfluorocarbons, fluoroethers, and fluoroalcohols.

[0033] In one embodiment, the hydrofluorocarbon solvent is a saturated or unsaturated compound containing only carbon, fluorine, and hydrogen atoms and having 3 to 9 and preferably 4 to 9 carbon atoms, wherein at least 50% of all atoms bonded to the carbon atoms are fluorine atoms. Examples thereof include saturated hydrofluorocarbons such as tridecafluorooctane, pentadecafluoroheptane, decafluoropentane, pentafluorobutane, pentafluoropropane, and heptafluorocyclopentane; and unsaturated hydrofluorocarbons such as hydrofluoroolefins (HFOs) represented by the following general formula (I):

[0034] Rf-CH2CH=CHCH2-Rf...(I)

[0035] (wherein each Rf is independently a perfluoroalkyl group).

[0036] In one embodiment, decafluoropentane represented by C5H2F 10 is used as the saturated hydrofluorocarbon. There are many structural isomers of decafluoropentane, and mixtures thereof can be used. In a preferred embodiment, 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 and another decafluoropentane isomer is used. In one embodiment, examples of the unsaturated hydrocarbon include 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf) and Z-1,1,1,4,4,4-hexafluoro-2-butene (Z-HFO-1336mzzm).

[0037] In one embodiment, the perfluorocarbon solvent includes saturated or unsaturated compounds containing only carbon and fluorine atoms and having a carbon number of 1 to 9. Examples thereof include, for example, fully fluorinated alkanes and cycloalkanes, such as tetrafluoromethane, hexafluoroethane, octafluoropropane, decafluorobutane, dodecafluoropentane, tetra-decafluorohexane, octafluorocyclobutane, and perfluoromethylcyclohexane; and unsaturated perfluorocarbons, such as perfluoroolefins represented by the following general formula II:

[0038] CF2=CFRf....(II)

[0039] (wherein Rf is a perfluoroalkyl group),

[0040] such as perfluoroheptene. Perfluoroheptene has perfluoro-2-heptene and perfluoro-3-heptene as isomers, and these isomers can be used alone or as a mixture.

[0041] In one embodiment, the fluoroether solvent includes ethers containing fluorine, and examples thereof include hydrofluoroethers (HFE) and perfluoroethers (PFE).

[0042] In one embodiment, the hydrofluoroether (HFE) includes saturated or unsaturated compounds having an ether bond, and examples thereof include hexafluoroisopropanol, trifluoroethanol, tetrafluoroethanol, pentafluoropropanol, 1,1,1-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, nonafluorobutyl methyl ether, and alkoxy perfluoroolefins. In one embodiment, hydrofluoroethers having a carbon number of 3 to 8 are preferred. In one embodiment, the fluorinated alcohol includes saturated fluorocarbons having an -OH functional group, and examples thereof include hexafluoroisopropanol, trifluoroethanol, tetrafluoroethanol, and pentafluoropropanol. In one embodiment, fluorinated alcohols having a carbon number of 2 to 8 are preferred.

[0043] In one embodiment, the HFE is an alkoxy perfluoroolefin, including methoxy perfluoroolefins and ethoxy perfluoroolefins having a carbon number of 5 to 10, and preferred examples include methoxy perfluoropentene, methoxy perfluorohexene, methoxy perfluoroheptene, methoxy perfluorooctene, ethoxy perfluoropentene, ethoxy perfluorohexene, ethoxy perfluoroheptene, ethoxy perfluorooctene, and mixtures thereof. There are various structural isomers of alkoxy perfluoroolefins, however, their structures are not particularly limited. Mixtures thereof can be used, and structures suitable for the purposes of the present invention can be appropriately selected.

[0044] In one embodiment, examples include methoxy perfluoroheptene, its isomers, and mixtures thereof. The following are examples of the structure of methoxy perfluoroheptene, but any structure may be used: CF3(CF2)2CF=CFCF(OCH3)CF3, CF3CF2CF=CF(CF2)2(OCH3)CF3, CF3CF2CF=CFCF(OCH3)CF2CF3, CF3CF=CFCF(OCH3)(CF2)2CF3, CF3CF=CFCF2CF(OCH3)CF2CF3, CF3CF2CF=C(OCH3)(CF2)2CF3, and CF3CF2C(OCH3)=CFCF2CF2CF3.

[0045] Examples of HFEs that may be suitably used include Vertrel (registered trademark) Suprion manufactured by Chemours-Mitsui Fluoroproducts Co., Ltd., and Novec (registered trademark) 7200, Novec (registered trademark) 7500, and Novec (registered trademark) 7600 manufactured by Sumitomo 3M Co., Ltd.

[0046] Examples of perfluoroethers include perfluoro(alkyl)alkyl ethers such as perfluoro(propyl)methyl ether, perfluoro(butyl)methyl ether, perfluoro(hexyl)methyl ether, and perfluoro(butyl)ethyl ether.

[0047] The analytical solvent according to the present invention can be appropriately selected according to the type of fluorine-containing contaminant substance to be extracted from the surface of the fluororesin melt-molded product. The boiling point difference relative to the fluorine-containing substance is preferably large, and more preferably not less than 10 °C. That is, as described below, since the decomposition of the fluorine-containing substance targeted by the analytical solvent of the present invention starts at about 150 °C, when the standard boiling point of the analytical solvent approaches 150 °C, the fluorine-containing substance starts to decompose, which can cause a reduction in the non-volatile residue of the fluorine-containing substance and make quantitative analysis or qualitative analysis difficult. Specifically, the analytical solvent of the present invention is preferably a gas or liquid at room temperature (20 °C - 25 °C), and preferably has a standard boiling point that does not break the molecular structure of the fluorine-containing substance, and the analytical solvent has a standard boiling point of 0 °C to 120 °C, preferably 0 °C to 70 °C, and more preferably 20 °C to 70 °C. In addition, from the perspective of operability, the standard boiling point is preferably at least 20 °C higher than room temperature.

[0048] In addition, the analytical solvent of the present invention preferably does not leave the components of the analytical solvent itself as non-volatile residues. The fact that the non-volatile residues of the solvent for gas chromatography-mass spectrometry do not remain is preferred because a fluorine-containing substance free of impurities can be obtained in the form of non-volatile residues, and the separation from the fluorine-containing substance becomes easy in GC-MS measurement. Even if the fluorine-containing substance is soluble, if the solvent components remain as non-volatile residues - for example, in the case of propylene glycol monomethyl ether acetate (PGMEA) - then the components of PGMEA itself will remain as non-volatile residues, which is not preferred because it will be difficult to separate from the fluorine-containing substance in GC-MS measurement.

[0049] From the perspective of the purity of the above non-volatile residues, in one embodiment, the analytical solvent of the present invention is 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.

[0050] Fluorinated pollutant substances to be analyzed

[0051] Examples of the fluorine-containing contaminant substances to be dissolved in the analytical solvent of the present invention include trace deposits attached to the surface (inner surface or outer surface) of a molded product obtained by melt molding a fluororesin (e.g., Figure 8 a perfluoroalkoxy resin (PFA) tube in Figure 8 ), as shown in the conceptual diagram of

[0052] Such trace fluorine-containing substances are compounds that are non-polar or moderately polar in terms of polarity, have a low molecular weight, start to decompose at about 150 °C, and evaporate at a temperature of about 300 °C or lower under normal pressure. Such trace fluorine-containing substances are compounds that are difficult to dissolve in solvents commonly used for GC-MS analysis such as ammonia, acetone, or purified water. Additionally, due to the minute amount, fluorine-containing substances are not detected even in GC-MS, and it is difficult to detect them through qualitative and quantitative analysis.

[0053] Therefore, only by using the method for quantitative determination of fluorine-containing substances and the method for qualitative analysis of fluorine-containing substances according to the present invention, can quantitative and qualitative analysis become possible. Furthermore, by using the evaporation and drying step, impurities in the fluorine-containing substances are removed, and trace fluorine-containing substances are condensed and quantified. Additionally, when the evaporated and dried fluorine-containing substances are dissolved in the solvent for gas chromatography-mass spectrometry according to the present invention, the concentration of the fluorine-containing substances in the obtained analysis specimen can be concentrated to a concentration that can be analyzed by GC-MS analysis.

[0054] As a result, it is possible to determine the presence or absence of trace causative substances (fluorine-containing substances) that can cause nanoparticles (contaminant fine particles), and the generation of nanoparticles (contaminant fine particles) that cause defects in the circuit patterns of semiconductor devices can be suppressed.

[0055] In GC-MS analysis, usually the extract solution is directly subjected to GC-MS analysis in order to identify the extract. In GC-MS analysis, it is usually most likely to perform GC-MS to directly analyze the extract in order to identify the extract. However, in the present invention, even if the extract solution is directly subjected to GC-MS analysis, only the analysis solvent such as 1,1,1,2,3,4,4,5,5,5-decafluoropentane is shown in the chromatogram, and no GC peak derived from the extract is detected (see Figures 5 to 7; The MS spectrum of the fluorine-containing substance, which is the pollutant, cannot be obtained from these results). Generally speaking, the conclusion usually drawn from such results is that the problematic fluorine-containing substance component is not contained in the extract solution. However, in order to explore the possibility that the extract components might be contained in the extract solution, the present inventors attempted to concentrate the extract solution. When the analysis target is a substance other than the fluorine-containing substance, the solvent can be evaporated and concentrated to a concentration of about 30 to 100 times before use. However, in the case of trace fluorine-containing substances in the present invention, when the concentration is about 30 to 100 times, nothing is detected in the GC-MS analysis, and quantitative determination will also be extremely difficult. By concentrating the substance to a dry state (which is the final concentration state), a certain amount of solid is obtained - although this amount is tiny - but it can be observed and weighed. Surprisingly, it was found that the solid obtained by this evaporation and drying is soluble in the fluorine-containing solvents of the present invention such as 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0056] As a result of the qualitative analysis method of the present invention described below, the fluorine-containing substance of the present invention exhibits significant peaks (fragments) in the mass spectra at 69 (CF3), 100 (C2F4), 119 (C2F5), 131 (C3F5), 169 (C3F7), 181 (C4F7), 219 (C4F9), 269 (C5F 11 ) etc. When performing melt extrusion of a fluororesin (for example, pipe molding), for the types of peaks of the fluorine-containing substance deposits attached to the inner surface of the shaping die of the melt extruder, these peaks are common, as is clear from the mass spectra showing Examples 9 and 10 described below Figure 3 and Figure 4 clearly show. It is believed that such substances (i.e., fluorine-containing substances) are formed by the thermal decomposition of the unstable end groups of the fluororesin chains or the fluororesin main chain itself in a molten state, thereby generating gaseous degradation products of the fluororesin containing fluorine. When the molten fluororesin cools, the degradation products are deposited on the surface of the formed fluororesin melt-molded product. Therefore, a correlation is observed between the amount of deposits attached to a part of the inner and outer surfaces of the shaping die of the melt extruder and the amount of fluorine-containing substances attached to the inner surface of the fluororesin molded product. Reducing the amount of such deposits on the outer surface of the shaping die also makes it possible to suppress the generation of the causative substance (fluorine-containing substance) of nano-scale particles (contaminant fine particles), which can cause defects in the circuits of semiconductor devices.

[0057] Quantitative determination method

[0058] In one embodiment, a method for quantitatively determining a fluorine-containing substance contaminating the surface of a fluororesin melt-molded product includes: dissolving and extracting the fluorine-containing substance on the surface of the fluororesin melt-molded product to form an extract solution, evaporating the extract solution to dryness to obtain the fluorine-containing substance as a non-volatile residue; and then determining the amount of the non-volatile residue. In one embodiment, quantitative determination is performed using an electronic balance, and evaporation and drying are performed using an evaporator. In a further embodiment, this quantitative method further includes pretreating the fluororesin melt-molded product before the dissolving and extracting step. In one embodiment, the pretreatment involves contacting the fluororesin melt-molded product with a liquid medium for the purpose of reducing the amount of small particles such as nanoparticles (fine contaminant particles of the fluorine-containing substance). In some embodiments, such liquid media include ultrapure water, ammonia diluent, diluted aqueous solution of surfactant, strong acid, ultrapure water, etc. In some embodiments, such liquid media include solvents for gas chromatography-mass spectrometry, including fluorine-containing solvents as described above.

[0059] Qualitative analysis method

[0060] In one embodiment, the present invention includes a method for qualitatively analyzing a fluorine-containing substance contaminating the surface of a fluororesin melt-molded product, the method including: dissolving and extracting the fluorine-containing substance on the surface of the fluororesin melt-molded product to form an extract solution; evaporating the extract solution to dryness to obtain the fluorine-containing substance as a non-volatile residue; dissolving the non-volatile residue in a solvent for gas chromatography-mass spectrometry, the solvent including a fluorine-containing solvent as described above; and subjecting the resulting solution to gas chromatography-mass spectrometry (GC-MS) analysis to obtain a total ion chromatogram (TIC) in the range of 0 to 500 mass numbers in the GC-MS, and performing qualitative analysis based on the mass-to-charge ratio (m / Z) of the mass spectrum at each gas chromatography peak.

[0061] Since the gas chromatogram of the analytical solvent background and the spectrum of the fluorine-containing substance can be easily separated for the analytical specimen, it is easy to remove the solvent background components from the spectrum of the fluorine-containing substance obtained by GC-MS analysis, which is preferred because more accurate qualitative and quantitative analysis is possible.

[0062] In some embodiments, the temperature when obtaining the extract solution or the analytical specimen by dissolving and extracting the fluorine-containing substance is not higher than 150 °C (for example, not higher than the temperature at which the fluorine-containing substance contaminant of the present invention starts to decompose). In another embodiment, from the perspective of the operability of the analytical solvent, this temperature is from room temperature to 60 °C. This is preferred when using an analytical solvent having a standard boiling point within this temperature range because the analytical solvent is removed by evaporation in a short time and the characteristics of the fluorine-containing substance are maintained.

[0063] It should be noted that the analytical specimen for GC-MS analysis used in the present invention can also be used after dissolving a reference substance in the analytical specimen. When decafluoropentane is used as the solvent for GC-MS analysis, isopropyl alcohol (IPA) can be used as the reference substance. In this case, the component can be qualitatively analyzed based on the patterns of the chromatogram of the reference solution obtained by dissolving the reference substance in the above solvent for mass spectrometry and the chromatogram of the analytical specimen containing the reference substance.

[0064] Fluororesin molded product

[0065] In one embodiment, in the fluororesin molded product of the present invention, the non-volatile residue of the fluorine-containing substance quantified by the quantitative determination method of the present invention is 20×10 -6 mg / mm 2 or less, or 0 mg / mm 2 to 20×10 -6 mg / mm 2 or preferably 0.01×10 -6 mg / mm 2 to 20×10 -6 mg / mm 2 or more preferably 0.01×10 -6 mg / mm 2 to 15×10 -6 mg / mm 2 . In the fluororesin molded product having a non-volatile residue within this range, the causative substance (fluorine-containing substance) that causes the generation of nanoscale particles is suppressed. This results in a fluororesin molded product in which the generation of nanoscale particles (contaminant fine particles) is also suppressed, and these particles adhere to the wafer surface during the semiconductor manufacturing process and cause defects in the fine semiconductor device circuit pattern. The particle size and number of nanoscale particles (contaminant fine particles) can be measured using a particle counter (particle counter in liquid) or the like.

[0066] In one embodiment, the fluororesin in the fluororesin molded product of the present invention is a tetrafluoroethylene (TFE) homopolymer (PTFE) or a copolymer of tetrafluoroethylene (TFE) and at least one type of fluorinated monomer (comonomer) copolymerizable with TFE, and is preferably such a copolymer that has 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 melt molding method. For example, in melt molding such as melt extrusion 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. In some embodiments, the fluororesin for the fluororesin molded product includes a mixture of fluororesins. For example, a mixture of PTFE and PFA, or PTFE and FEP, or PFA and FEP, or a mixture of the same type of fluororesin, such as a mixture of at least two different PFA copolymers.

[0067] Such copolymers are copolymers containing 40 mol% to 99 mol% of TFE units and 1 mol% to 60 mol% of at least one type of comonomer. Examples of comonomers include perfluoroolefins having 3 or more carbon atoms, perfluoro(alkyl vinyl ethers) (PAVE) (the alkyl group being a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms), vinylidene fluoride, and vinyl fluoride.

[0068] Examples of preferred TFE copolymers include TFE / hexafluoropropylene (HFP) copolymers (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymers (PFA), TFE / HFP / PAVE copolymers, and mixtures of these copolymers. More preferably, at least one type of copolymer is selected from TFE / perfluoro(ethyl vinyl ether) (PEVE) copolymers, TFE / perfluoro(propyl vinyl ether) (PPVE) copolymers, and TFE / perfluoro(butenyl vinyl ether) copolymers. The amount of PAVE units in these copolymers is preferably 1 mol% to 30 mol%, and more preferably 1 mol% to 20 mol%. Additionally, the amount of hexafluoropropylene units in the FEP copolymer is preferably 1 mo1% to 10 mol%.

[0069] In one embodiment, in order to suppress the generation of pyrolyzates that promote the fluorine-containing substances of the present invention to become non-volatile residues, (fluorinated, fluorine-treated) and thus more thermally stable copolymers may also be used, in which unstable chain end groups such as -CF=CF2, -CO2H, -CF2CH2OH, -CONH2, and -COF are converted to thermally stable -CF3 chain end groups.

[0070] Such polymers can be in any form, such as powders, particulate products of powders, particulate substances, flakes, pellets, small pieces or beads.

[0071] Examples of the fluororesin molded products of the present invention include pellets, beads, bottles, films, tubes, sheets, pipes, pipe fittings, gaskets, O-rings, pumps, valves, filter housings, regulators and conveying members (wafer carriers).

[0072] The molding method of the fluororesin molded product of the present invention is not particularly limited, and conventional known molding methods can be employed according to the fluororesin used. Examples of the molding methods include compression molding, paste extrusion, melt compression molding, melt extrusion, injection molding, transfer molding, blow molding, rotational molding, lining molding and film molding.

[0073] By using a solvent for GC-MS analysis, including a fluorinated solvent in the qualitative and quantitative analysis methods of the present invention, fluorinated substances are easily extracted, which enables more precise qualitative and quantitative analysis of trace fluorinated substances. The present invention makes it possible to obtain such a fluororesin molded product in which the generation of nanoparticles is suppressed by using the qualitative and quantitative analysis methods of the present invention.

[0074] In addition, even without using pyrolysis-GC-MS combined with an expensive heating device (pyrolyzer), precise qualitative and quantitative analysis of trace fluorinated substances is possible, which was difficult to qualitatively and quantitatively analyze in the past.

[0075] Example

[0076] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0077] Note that the materials and measurement methods used in the examples are as follows.

[0078] Material

[0079] 1. Fluororesin

[0080] (1) PFA(1)

[0081] Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer

[0082] (Melting point: 310 °C; ζ potential at pH = 7: -50 mV)

[0083] (2) PFA(2)

[0084] Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer

[0085] (Melting point: 263 °C; ζ potential at pH = 7: -80 mV)

[0086] 2. Fluororesin molded product (PFA tube)

[0087] At the molding temperature shown in Table 1 or Table 2, using PFA (1) or (2), and using a φ30 mm melt extruder (an extrusion device manufactured by Pla Giken Co., Ltd.), an unstretched tube with an outer diameter of 6.35 mm, an inner diameter of 4.35 mm, and a length of 50 m was obtained.

[0088] 3. Solvent for GC-MS analysis

[0089] (1) 1,1,1,2,3,4,4,5,5,5 - decafluoropentane

[0090] (Vertrel (registered trademark) XF (manufactured by Chemours Mitsui Fluoroproducts Co., Ltd., standard boiling point: 55 °C)

[0091] (represented as (1) in the table below)

[0092] (2) Methoxyperfluoroheptene: Vertrel (registered trademark) Suprion TM

[0093] (manufactured by Chemours Mitsui Fluoroproducts Co., Ltd., standard boiling point: 110 °C)

[0094] (represented as (2) in the table below)

[0095] (3) Tetradecafluoroheptene

[0096] (manufactured by Chemours Mitsui Fluoroproducts Co., Ltd., standard boiling point: 75 °C to 85 °C)

[0097] (represented as (3) in the table below)

[0098] Example 1

[0099] First, by bending both ends by 100 mm and using a plastic tape, 1,1,1,2,3,4,4,5,5,5 - decafluoropentane ( XF) was sealed in a 50 m fluororesin molded product (tube, outer diameter: 6.35 mm, inner diameter: 4.35 mm) made of PFA (1), and then it was left standing in an oven at 60 °C for 24 hours, and it was removed using nitrogen to form an extract solution. Then, 500 ml of the extract solution was evaporated and dried using an evaporator, and the amount of non - volatile residue was weighed using an electronic balance as the fluorine - containing substance attached to the inner surface of the fluororesin molded product (tube). The results are shown in Table 1.

[0100] Dissolve the weighed fluorine-containing substance in 500 μl (microliters) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane ( XF) (which is a solvent for gas chromatography-mass spectrometry according to the present application) to obtain an analytical specimen. The ratio of the fluorine-containing substance to the solvent for gas chromatography-mass spectrometry according to the present application is 1 mg / 10 μl. Using the obtained analytical specimen, obtain a total ion chromatogram (TIC) in the range of 0 to 500 mass numbers in gas chromatography-mass spectrometry (GC-MS), and then confirm the mass-to-charge ratio (m / Z) of the spectrum at each peak. The results are shown in Figure 1 .

[0101] Examples 2 to 4

[0102] First, bend both ends by 100 mm and use a plastic tape to seal the pretreatment solvent shown in Table 2 in a 50 m fluororesin molded product (tube, outer diameter: 6.35 mm, inner diameter: 4.35 mm), and then leave it standing in an oven at 60 °C for 24 hours (pretreatment cleaning), and dry the tube at room temperature using nitrogen gas.

[0103] Next, seal 1,1,1,2,3,4,4,5,5,5-decafluoropentane ( XF) similarly in the dried tube, and then leave it standing in an oven at 60 °C for 24 hours, remove it using nitrogen gas and store it in a glass vial to form an extract solution. Then, evaporate and dry 500 ml of the extract solution using an evaporator, and weigh the amount of the non-volatile residue as the fluorine-containing substance attached to the surface of the fluororesin molded product (tube). The results are shown in Table 1.

[0104] Example 5

[0105] Except for using a fluororesin molded product made of PFA(2), in the same manner as in Example 1, weigh the amount of the fluorine-containing substance using an electronic balance, and then confirm the mass-to-charge ratio (m / Z) of the spectrum at each peak. The results are shown in Table 2 and Figure 2 .

[0106] Examples 6 to 8

[0107] Except for using PFA(2) as the fluororesin, in the same manner as in Examples 2 to 4, weigh the amount of the fluorine-containing substance using an electronic balance. The results are shown in Table 2.

[0108] Example 9

[0109] Except for using 3 mg of the deposit attached to the outer surface of the shaping die of the φ30 mm melt extruder for pipe molding in Example 1 as the fluorine-containing substance and dissolving the deposit in 500 μl (microliters) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane ( XF) used as the solvent for gas chromatography - mass spectrometry according to the present invention to obtain an analytical specimen, the mass-to-charge ratio (m / Z) of the spectrum at each peak was confirmed in the same manner as in Example 1. The results are shown in Figure 3 .

[0110] Example 10

[0111] Except for using 3 mg of the deposit attached to the outer surface of the shaping die of the Φ30 mm melt extruder for pipe molding in Example 2 as the fluorine-containing substance and dissolving the deposit in 500 μl (microliters) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane ( XF) used as the solvent for gas chromatography - mass spectrometry according to the present invention to obtain an analytical specimen, the mass-to-charge ratio (m / Z) of the spectrum at each peak was confirmed in the same manner as in Example 2. The results are shown in Figure 4 .

[0112] Reference Examples 1 and 2

[0113] Using the extract solution of Example 2 or 5, a total ion chromatogram (TIC) in the range of 0 to 650 mass numbers in gas chromatography - mass spectrometry (GC-MS) was obtained. The results are shown in Figure 5 and Figure 6 . It can be seen that no peaks (fragments) were observed or detected in GC-MS.

[0114] Reference Example 3

[0115] The result of the total ion chromatogram (TIC) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane ( XF) used as the solvent for gas chromatography - mass spectrometry according to the present invention is shown in Figure 7 .

[0116] From the comparison of Figure 5 and Figure 6 and Figure 7 , it can be seen that no peaks (fragments) were confirmed or detected in the total ion chromatogram (TIC) of the extract solution of Example 2 or 5.

[0117] Reference Examples 4 to 8

[0118] First, 3 mg of the deposit adhering to the outer surface of the shaping die of the melt extruder used in Example 1 was separately immersed in 3 g of the solvents for GC-MS analysis shown in Table 3, and was subjected to ultrasonic treatment at room temperature (20 °C) for 5 minutes, and then left standing for 12 hours. The state after standing was visually confirmed, and the case where solid substances or deposits could be confirmed was evaluated as ×, while the case where solid substances or deposits could not be confirmed was evaluated as ○. The results are shown in Table 3.

[0119] As Figures 1 to 8 clearly shows, the extraction solvent, quantitative determination method, and qualitative analysis method of the present invention have produced remarkable effects, that is, trace fluorine-containing substances can be quantified, and qualitative analysis can also be performed by GC-MS.

[0120] In addition, in Figures 1 to 4 it can be seen that peaks such as 69 (CF3), 100 (C2F4), 119 (C2F5), 131 (C3F5), 169 (C3F7), 181 (C4F7), 219 (C4F9), and 269 (C5F 11 ) can be confirmed as fragment ions of fluorine-containing substances. Therefore, it can be seen that if these common peaks are reduced or disappear in Figure 1 and Figure 2 , the causative substances that cause defects in the circuit patterns of semiconductor devices due to fluorine-containing substances in the form of nanoscale particles (contaminant fine particles) can be reduced.

[0121] Table 1

[0122]

[0123] Table 2

[0124]

[0125]

[0126] Table 3

[0127] Reference Example 4 Reference Example 5 Reference Example 6 Reference Example 7 Reference Example 8 Reference Example 9 Fluororesin PFA(2) PFA(2) PFA(2) PFA(2) PFA(2) PFA(2) Solvent for GC-MS analysis (2) (3) IPA Acetone 3%NH4 Purified water Solubility ○ ○ × × × ×

[0128] The present invention enables more precise quantitative determination and qualitative analysis of fluorine-containing substances contaminating the surface of fluororesin melt-molded products.

[0129] By using the quantitative determination method and qualitative analysis method of the present invention, it is possible to determine whether nanoscale particles (contaminant fine particles) are generated. Accordingly, it is possible to obtain a fluororesin molded product in which the generation of nanoscale particles (contaminant fine particles) is suppressed and the occurrence of defects in a semiconductor device circuit pattern can be suppressed.

[0130] In addition, even without using pyrolysis-GC-MS incorporating an expensive heating device (pyrolyzer), it is possible to accurately qualitatively and quantitatively analyze trace fluorine-containing substances, which has been difficult to qualitatively and quantitatively analyze in the past.

[0131] Additional exemplary embodiments

[0132] Embodiment 1 is a solvent for gas chromatography-mass spectrometry of a fluorine-containing substance, the solvent including a fluorine-containing solvent.

[0133] Embodiment 2 is the solvent for gas chromatography-mass spectrometry according to Embodiment 1, wherein the fluorine-containing solvent is at least one selected from hydrofluorocarbons, perfluorocarbons, fluorine-containing ethers, and fluorine-containing alcohols.

[0134] Embodiment 3 is the solvent for gas chromatography-mass spectrometry according to Embodiment 1 or 2, wherein the fluorine-containing solvent is a fluorine-containing solvent having a standard boiling point of 0°C to 120°C.

[0135] Embodiment 4 is the solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 3, wherein the fluorine-containing solvent is a fluorine-containing solvent having a standard boiling point of 20°C to 70°C.

[0136] Embodiment 5 is the solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 4, wherein the fluorine-containing solvent is decafluoropentane.

[0137] Embodiment 6 is the solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 5, wherein the fluorine-containing solvent is 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0138] Embodiment 7 is the solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 6, wherein the fluorine-containing substance is a fluorine-containing substance attached to the surface of a fluororesin molded product.

[0139] Embodiment 8 is a method for quantitatively determining a fluorine-containing substance, the method including: evaporating and drying an extract solution prepared by dissolving and extracting the fluorine-containing substance to obtain a non-volatile residue of the extract; and then determining the amount of the non-volatile residue.

[0140] Embodiment 9 is a method for quantitative determination of fluorine-containing substances according to Embodiment 8, the method further comprising: pretreating a fluororesin molded product, and then evaporating and drying an extract solution prepared by dissolving and extracting fluorine-containing substances in a solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 7 to obtain a non-volatile residue of the extract solution; and then determining the amount of the non-volatile residue.

[0141] Embodiment 10 is a method for qualitative analysis of fluorine-containing substances, the method comprising: using an analytical specimen obtained by dissolving a non-volatile residue quantified by the quantitative determination method for fluorine-containing substances according to Embodiment 8 or 9 in a solvent for gas chromatography-mass spectrometry according to any one of Embodiments 1 to 7 to obtain a total ion chromatogram (TIC) in a mass number range of 0 to 500 in gas chromatography-mass spectrometry (GC / MS); and then performing qualitative analysis based on the mass-to-charge ratio (m / Z) of the mass spectrum at each peak.

[0142] Embodiment 11 is a fluororesin molded product, wherein the non-volatile residue of the fluorine-containing substance quantified by the quantitative determination method according to Embodiment 8 or 9 is 0×10 -6 mg / mm 2 to 20×10 -6 mg / mm 2 .

Claims

1. Use of a solvent in the gas chromatography - mass spectrometry analysis of a fluorine - containing substance for adhering to the surface of a fluororesin melt - molded product, the solvent comprising a fluorinated solvent, wherein the fluorinated solvent is 1,1,1,2,3,4,4,5,5,5 - decafluoropentane, and wherein the fluorine - containing substance is dissolved in the fluorinated solvent.

2. A method for quantitatively determining a fluorine-containing substance that contaminates the surface of a fluororesin melt-molded product, the method comprising: Dissolve and extract the fluorine - containing substance on the surface of a fluororesin melt - molded product using a solvent comprising a fluorinated solvent for gas chromatography - mass spectrometry analysis, wherein the fluorinated solvent is 1,1,1,2,3,4,4,5,5,5 - decafluoropentane, and evaporate the extract solution to dryness to obtain the fluorine - containing substance as a non - volatile residue; And then determine the amount of the non - volatile residue.

3. The method according to claim 2, wherein the method further comprises: Pretreat the fluororesin melt - molded product before the dissolution and extraction step.

4. The method according to claim 2, wherein the amount of the non-volatile residue is 20×10 -6 mg / mm 2 or less.

5. A method for qualitative analysis of a fluorine - containing substance contaminating the surface of a fluororesin melt - molded product, the method comprising: Dissolve and extract the fluorine - containing substance on the surface of a fluororesin melt - molded product to form an extract solution, Evaporate the extract solution to dryness to obtain the fluorine - containing substance as a non - volatile residue; Dissolve the non - volatile residue in a solvent for gas chromatography - mass spectrometry analysis, the solvent comprising a fluorinated solvent, wherein the fluorinated solvent is 1,1,1,2,3,4,4,5,5,5 - decafluoropentane, and Subject the resulting solution to gas chromatography - mass spectrometry analysis to obtain a total ion chromatogram in the range of 0 to 500 mass numbers in GC - MS, and perform qualitative analysis by the mass - to - charge ratio of the mass spectrum at each gas chromatography peak.

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