Cleaning sheet, conveying member with cleaning function, and method for manufacturing a cleaning sheet

Abstract

To provide a cleaning sheet with excellent cleanliness, foreign matter removal performance, and transport performance. [Solution] The cleaning sheet according to an embodiment of the present invention comprises a cleaning layer, the cleaning layer contains a polyimide resin, and the amount of metal transferred to the silicon wafer by total internal reflection X-ray fluorescence analysis is 1 × 10⁻⁶ 11 atoms / cm 2 The following applies:

Description

[Technical Field]

[0001] The present invention relates to a cleaning sheet, a conveying member with a cleaning function, and a method for manufacturing a cleaning sheet. [Background technology]

[0002] In various substrate processing equipment, such as manufacturing and inspection equipment for semiconductors, flat panel displays, and printed circuit boards, where foreign matter is undesirable, the substrate is transported while in physical contact with the transport device (typically a chuck table). If foreign matter adheres to the transport device, it will contaminate subsequent substrates, requiring periodic shutdown and cleaning. This resulted in problems such as reduced operating rates and the significant effort required for cleaning. Furthermore, there was a risk of contamination by human-derived foreign matter during the cleaning process.

[0003] To overcome these problems, a method has been proposed (see Patent Document 1) in which foreign matter adhering to a conveying device is removed by conveying a plate-shaped member into a substrate processing device. With this method, it is not necessary to stop the substrate processing device and perform cleaning, thus resolving the problem of reduced operating rate of the processing device. However, this method does not sufficiently remove foreign matter adhering to the conveying device.

[0004] Furthermore, a method has been proposed (see Patent Document 2) in which a substrate to which an adhesive substance has been fixed is transported into a substrate processing apparatus as a cleaning member to remove foreign matter adhering to the transport device. This method is superior in foreign matter removal performance compared to the method described in Patent Document 1. However, in the method described in Patent Document 2, a problem may arise in which the contact area between the adhesive substance and the transport device adheres too strongly and becomes difficult to separate. As a result, problems may arise such as the substrate to which the adhesive substance has been fixed cannot be reliably transported, the transport device may be damaged, and the transport device may be contaminated. On the other hand, if the adhesion force between the adhesive substance and the transport device becomes too weak, the foreign matter removal performance of the cleaning member will decrease, and a problem may arise in which a sufficient cleaning effect cannot be obtained.

[0005] Furthermore, depending on the composition and manufacturing method of the cleaning components, the cleaning components themselves can become a source of contamination in the manufacturing process, which is also a problem. Metal impurities, in particular, can be a serious cause of defects in substrate (wafer) processing. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-87458 [Patent Document 2] Japanese Patent Application Publication No. 10-154686 [Patent Document 3] Japanese Patent Publication No. 2007-307521 [Patent Document 4] Japanese Patent Publication No. 2010-259970 [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a cleaning sheet that is excellent in cleanliness, foreign matter removal performance, and transport performance. [Means for solving the problem]

[0008] 1. The cleaning sheet according to an embodiment of the present invention comprises a cleaning layer, the cleaning layer contains a polyimide resin, and the amount of metal transferred to the silicon wafer by total internal reflection X-ray fluorescence analysis is 1 × 10⁻¹⁶ 11 atoms / cm 2 The following applies: 2. In the cleaning sheet described in 1 above, the amount of Ca transferred to the silicon wafer by total internal reflection X-ray fluorescence analysis of the cleaning layer is 1 × 10 11 atoms / cm 2 The following is also acceptable. 3. In the cleaning sheet described in 1 or 2 above, the amount of metal in the cleaning layer may be 10 ppm or less. 4. In the cleaning sheet described in any of items 1 to 3 above, the amount of Na and Ca in the cleaning layer may both be 10 ppm or less. 5. In the cleaning sheet described in any of items 1 to 4 above, the indentation modulus of the cleaning layer at 25°C may be 0.1 GPa to 2 GPa. 6. A cleaning sheet according to any one of items 1 to 5 above may further include a support disposed adjacent to the cleaning layer. 7. A transport member with a cleaning function according to an embodiment of the present invention comprises a cleaning sheet and a transport member as described in any of 1 to 6 above. 8. A method for manufacturing a cleaning sheet according to an embodiment of the present invention comprises coating a support with a cleaning layer forming composition, wherein the Na concentration and Ca concentration in the cleaning layer forming composition are both 10 ppm or less. 9. The method for manufacturing a cleaning sheet as described in 8 above may further include a step of measuring the Na concentration or Ca concentration in the cleaning layer forming composition. [Effects of the Invention]

[0009] According to the present invention, a cleaning sheet with excellent cleanliness, foreign matter removal performance, and transport performance can be provided.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic cross-sectional view of a cleaning sheet according to an embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view of a cleaning sheet according to an embodiment of the present invention. [Figure 3] It is a schematic cross-sectional view of a cleaning sheet according to an embodiment of the present invention. [Figure 4] It is a schematic cross-sectional view of a conveying member with a cleaning function according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0011] A. Cleaning sheet A-1. Overview The cleaning sheet according to an embodiment of the present invention includes a cleaning layer. The cleaning sheet according to an embodiment of the present invention may be composed only of the cleaning layer, or may have other layers.

[0012] FIG. 1 is a schematic cross-sectional view showing one embodiment of a cleaning sheet according to an embodiment of the present invention. In FIG. 1, the cleaning sheet 100 has a cleaning layer 10 and a protective film 20 disposed on at least one side of the cleaning layer 10. The protective film 20 can be provided for the purpose of protecting the cleaning layer 10 and the like, and may be omitted according to the purpose. That is, the cleaning sheet of the present invention may be composed only of the cleaning layer 10.

[0013] FIG. 2 is a schematic cross-sectional view showing another embodiment of a cleaning sheet according to an embodiment of the present invention. In FIG. 2, the cleaning sheet 100 has the protective film 20, the cleaning layer 10, and the adhesive layer 30 in this order. The protective film 20 can be provided for the purpose of protecting the cleaning layer 10 and the like, and may be omitted according to the purpose.

[0014] The cleaning sheet according to an embodiment of the present invention may further include a support body disposed adjacent to the cleaning layer. In one embodiment, the support body is disposed so as to be in contact with the cleaning layer. The support body can be a support for conveyance such as a dummy wafer. FIG. 3 is a schematic cross-sectional view showing another embodiment of the cleaning sheet according to an embodiment of the present invention. In FIG. 3, the cleaning sheet 100 has a protective film 20, a cleaning layer 10, a support body 40, and an adhesive layer 30 in this order. The protective film 20 can be provided for the purpose of protecting the cleaning layer 10 and the like, and may be omitted according to the purpose. Also, the adhesive layer 30 may be omitted.

[0015] A-2. Cleaning layer The amount of metal transferred to the silicon wafer by total reflection X-ray fluorescence analysis in the cleaning layer is 1×10 11 atoms / cm 2 or less. By configuring the cleaning layer in this way, a cleaning sheet excellent in cleanliness that can prevent contamination derived from the cleaning layer can be obtained. The cleaning sheet exhibits excellent performance as a cleaning member for a predetermined device by combining its own cleanliness and foreign matter removal performance. The cleaning layer as described above can be formed by using a clean cleaning layer-forming composition (varnish). In one embodiment, the cleanliness of the cleaning layer-forming composition (varnish) can be evaluated by the amounts of Na and Ca in the varnish. Also, the cleaning layer as described above can be formed by forming it in a manufacturing process that does not rely on manual labor. Usually, the detection limit of the amount of metal transferred to the silicon wafer by total reflection X-ray fluorescence analysis is about 1×10 11 atoms / cm 2 In one embodiment, the lower limit of the amount of metal transferred to the silicon wafer is 0 atoms / cm 2 . Examples of the metal include Ti, Cr, Mn, Ni, Fe, Co, Cu, and Zn. For any of these metals, the amount of transferred metal is 1×10 11 atoms / cm2 The following is preferable. The method for measuring the amount of the above-mentioned transfer metal will be described later.

[0016] Preferably, the cleaning layer has a transfer amount of Ca to the silicon wafer determined by total internal reflection X-ray fluorescence analysis to be 1 × 10⁻⁶. 11 atoms / cm 2 The following applies. By configuring the cleaning layer in this way, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. Typically, the detection limit for the amount of Ca metal in a silicon wafer by total internal reflection X-ray fluorescence analysis is 1 × 10⁻⁶. 11 atoms / cm 2 It is approximately as follows. In one embodiment, the lower limit of the amount of metal transferred to the silicon wafer is 0 atoms / cm². 2 The above-mentioned amount of transferred Ca can be measured by the same method as the above-mentioned amount of transferred metal, except that the object of measurement is Ca.

[0017] The amount of metal in the cleaning layer is preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less. Within this range, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. Examples of the metals mentioned above include Ti, Cr, Mn, Ni, Fe, Co, Cu, and Zn. For any of these metals, it is preferable that the amount of metal in the cleaning layer is within the above range. The less the amount of metal in the cleaning layer, the better, and the lower limit is, for example, 1 ppm (preferably 0 ppm). The amount of metal in the cleaning layer, as well as the amount of Na and Ca described later, can be measured by ICP-MS as described later.

[0018] The amount of Na in the cleaning layer is preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less. Within this range, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. The amount of Na in the cleaning layer is preferably low, with a lower limit of, for example, 1 ppm (preferably 0 ppm).

[0019] The amount of Ca in the cleaning layer is preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less. Within this range, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. The amount of Ca in the cleaning layer is preferably low, with a lower limit of, for example, 1 ppm (preferably 0 ppm).

[0020] In one embodiment, the amount of Na and Ca in the cleaning layer is preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less.

[0021] The thickness of the cleaning layer is, for example, 1 μm to 100 μm. The thickness of the cleaning layer may also be 1 μm to 50 μm, 1 μm to 30 μm, or 1 μm to 20 μm.

[0022] In one embodiment, the cleaning layer is substantially non-adhesive. Specifically, the 180° peel-off adhesive force A, as defined in JIS-Z-0237, to the mirror surface of the silicon wafer is preferably less than 0.20 N / 10 mm, and more preferably 0.01 to 0.10 N / 10 mm. If the 180° peel-off adhesive force A of the cleaning layer to the mirror surface of the silicon wafer, as defined in JIS-Z-0237, is within this range, the cleaning layer is substantially non-adhesive, and the adhesion between the cleaning layer and, for example, the transport device in the substrate processing apparatus can be reduced. As a result, the substrate can be transported reliably, and the transport device may be less likely to be damaged.

[0023] The cleaning layer has a 180° peel-off adhesive force B against the mirror surface of the dummy wafer, preferably 2N / 10mm or more, more preferably 3N / 10mm or more, even more preferably 3.5N / 10mm or more, particularly preferably 5N / 10mm or more, and most preferably 7N / 10mm or more. If the 180° peel-off adhesive force B is within the above range, for example, the adhesion between the cleaning layer and the transport member such as the dummy wafer will be increased, and the cleaning layer will be less likely to peel off from the transport member such as the dummy wafer during cleaning. A higher 180° peel-off adhesive force B against the mirror surface of the dummy wafer is preferable, but its upper limit is, for example, 20N / 10mm (preferably 30N / 10mm, more preferably 50N / 20mm). The 180° peel-off adhesive force B is measured, for example, by forming the cleaning layer on the mirror surface of a silicon wafer used as a dummy wafer. The 180° peel adhesion strength B is measured for a sample piece measuring 10 mm wide x 100 mm long under ambient temperature of 23°C, a peel angle of 180°, and a tensile speed of 10 mm / min.

[0024] The indentation modulus of the cleaning layer at 25°C is preferably 0.1 GPa to 2 GPa, more preferably 0.2 GPa to 1.5 GPa, and even more preferably 0.5 GPa to 1.0 GPa. Within this range, organic contamination caused by the cleaning layer can be reduced. The indentation modulus of the cleaning layer can be measured using a nanoindenter (indenter: Berkovich (triangular pyramidal type)) at a frequency of 100 Hz, an indentation depth of 100 nm, a measurement sample size of 1.0 cm × 1.0 cm, and an amplitude of 2 nm.

[0025] The storage modulus of the cleaning layer at 25°C may be 100 MPa to 2500 MPa, 100 MPa to 2000 MPa, 100 MPa to 1500 MPa, or 100 MPa to 1000 MPa. Preferably, it is 100 MPa to 1000 MPa. Within the above range, a cleaning sheet with remarkably superior foreign matter removal performance can be obtained. The storage modulus can be measured using a solid viscoelasticity measuring device (for example, model RSAG-2, manufactured by T.A. Instrument Japan Co., Ltd.) on a test piece with a length of 30 mm (measurement length) and a width of 10 mm, under the conditions of a frequency of 1 Hz, a heating rate of 10°C / min, and a chuck distance of 10 mm.

[0026] The cleaning layer, after being processed by the cross-cutting method, preferably has a remaining cleaning layer count of 15 / 25 or more on the mirror surface of the dummy wafer, more preferably 18 / 25 or more, even more preferably 20 / 25 or more, particularly preferably 23 / 25 or more, and most preferably 25 / 25 or more. If the remaining cleaning layer count on the mirror surface of the dummy wafer after the cross-cutting method is within the above range, for example, the adhesion between the cleaning layer and the transport member such as the dummy wafer will be increased, and the cleaning layer will be less likely to peel off from the transport member such as the dummy wafer during cleaning.

[0027] The number of remaining cleaning layers on the mirror surface of a dummy wafer using the cross-cut method of the cleaning layer can be measured by, for example, making six parallel cuts at 2 mm intervals into the substrate on the test surface using a utility knife, and then making six more parallel cuts at 2 mm intervals perpendicular to the first cuts to create 25 grid lines. A tape with an adhesive strength of 16 N / 20 mm (for example, "BT-315ST" manufactured by Nitto Denko Corporation) is then firmly pressed onto the grid lines, and the end of the tape is quickly peeled off at a 45° angle. The state of the grid lines is then evaluated by comparing it with a standard diagram.

[0028] The above cleaning layer contains a polyimide resin. By providing a cleaning layer containing a polyimide resin, a cleaning sheet with excellent foreign matter removal performance and transport performance can be obtained. The content ratio of the polyimide resin in the cleaning layer is preferably 50 to 100 parts by weight, more preferably 70 to 100 parts by weight, even more preferably 90 to 100 parts by weight, particularly preferably 95 to 100 parts by weight, and most preferably 98 to 100 parts by weight, per 100 parts by weight of the cleaning layer. The polyimide resin preferably has soft segments. Soft segments are segments that can impart flexibility to the polymer, and may be, for example, segments having long-chain linear groups or long-chain branched groups in the main chain, and are soft and elastic.

[0029] Typically, polyimide resins are obtained by imidizing polyamic acid. Polyamic acid can be obtained by reacting a tetracarboxylic dianhydride component and a diamine component as monomer components in any suitable organic solvent. In one embodiment, these are reacted in substantially equimolar ratios. This reduces the amount of reaction residue, and as a result, a cleaning sheet with particularly excellent cleanliness can be obtained.

[0030] Examples of tetracarboxylic dianhydride components include 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic acid dianhydride, 2,2-bis(2,3-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, pyromellitic acid dianhydride, and ethylene glycol bistrimellitic acid dianhydride. These may be one type or two or more types.

[0031] Examples of diamine components include diamine compounds having at least two amine-containing terminals and a polyether structure (hereinafter also referred to as PE diamine compounds), aliphatic diamines, and aromatic diamines. Among these, PE diamine compounds are preferably used. Dimer amines may also be used as the diamine compound.

[0032] Any suitable compound can be used as the PE diamine compound. Examples of PE diamine compounds include terminal diamines having a polypropylene glycol structure, terminal diamines having a polyethylene glycol structure, terminal diamines having a polytetramethylene glycol structure, and terminal diamines having multiple of these structures. More specifically, examples of PE diamine compounds include PE diamine compounds having at least two terminals with amine structures prepared from ethylene oxide, propylene oxide, polytetramethylene glycol, polyamines, or mixtures thereof. Constituent units derived from PE diamine compounds can become soft segments in polyimide resins.

[0033] In the monomer components for forming the polyamic acid described above, the content of PE diamine is preferably 10 to 60 parts by weight, more preferably 12 to 50 parts by weight, even more preferably 15 to 45 parts by weight, and particularly preferably 20 to 40 parts by weight, per 100 parts by weight of the monomer components. Within this range, a cleaning sheet with particularly excellent foreign matter removal performance can be obtained. Furthermore, a cleaning layer-forming composition that readily forms varnishes can be obtained.

[0034] In the diamine component for forming the polyamic acid described above, the content of PE diamine is preferably 20 to 80 parts by weight, more preferably 25 to 75 parts by weight, and even more preferably 30 to 70 parts by weight, per 100 parts by weight of the diamine component. Within this range, a cleaning sheet with particularly excellent foreign matter removal performance can be obtained. Furthermore, a cleaning layer-forming composition that readily forms varnishes can be obtained.

[0035] Examples of aliphatic diamines include ethylenediamine, hexamethylenediamine, 1,8-,1,10-diaminodecane, 1,12-diaminododecane, 4,9-dioxa-1,12-diaminododecane, and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (α,ω-bisaminopropyltetramethyldisiloxane). The molecular weight of the aliphatic diamine is preferably 50 to 1,000,000, and more preferably 100 to 30,000.

[0036] Examples of aromatic diamines include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, and 4,4'-diaminobenzophenone.

[0037] Organic solvents (reaction solvents) used in the reaction between the tetracarboxylic dianhydride component and the diamine component include, for example, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N,N-dimethylformamide. Nonpolar solvents (e.g., toluene or xylene) may be used in combination to adjust the solubility of the raw materials.

[0038] The reaction temperature between the tetracarboxylic dianhydride and the diamine is preferably 20°C or higher, and more preferably 20°C to 100°C.

[0039] The imidation of polyamic acids is typically carried out by heat treatment under an inert atmosphere (typically a vacuum or nitrogen atmosphere). The heat treatment temperature is preferably 150°C or higher, and more preferably 180°C to 450°C.

[0040] The glass transition temperature (Tg) of the above polyimide resin is preferably 200°C to 300°C, more preferably 250°C to 300°C, and even more preferably 250°C to 285°C. Within this range, the effects of the present invention become particularly pronounced. The glass transition temperature (Tg) is measured by a thermomechanical analyzer (TMA).

[0041] The cleaning layer may contain any other suitable components, provided that they do not impair the effects of the present invention. Examples of such other components include heat-resistant resins, surfactants, plasticizers, antioxidants, conductivity imparters, ultraviolet absorbers, and light stabilizers.

[0042] A-3.Support The above cleaning sheet may include a support. The support may be a single layer or a multilayer structure.

[0043] The thickness of the support can be any appropriate thickness as long as it does not impair the effects of the present invention. Such a thickness is preferably 500 μm or less, more preferably 1 μm to 400 μm, even more preferably 1 μm to 300 μm, particularly preferably 1 μm to 200 μm, and most preferably 1 μm to 100 μm.

[0044] Any suitable material can be used as the material constituting the support, as long as it does not impair the effects of the present invention. Examples of support materials include films of plastics, engineering plastics, and super engineering plastics. Specific examples of plastics, engineering plastics, and super engineering plastics include polyimide, polyethylene, polyethylene terephthalate, acetylcellulose, polycarbonate, polypropylene, and polyamide.

[0045] The various physical properties of the support material, such as its molecular weight, can be appropriately selected depending on the purpose.

[0046] The method for molding the support can be appropriately selected depending on the purpose.

[0047] The surface of the support may be subjected to conventional surface treatments, such as chemical or physical treatments including chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, and ionizing radiation treatment, or coating treatment with an undercoat, in order to improve adhesion and retention with adjacent layers.

[0048] The peel force of the cleaning layer on the support at 23°C is, for example, 3 N / 10 mm or more, preferably 3.5 N / 10 mm or more, and more preferably 5 N / 10 mm or more. A higher peel force of the cleaning layer on the support at 23°C is preferable, but the upper limit is, for example, 50 N / 10 mm. The method for measuring the peel force is in accordance with the method for measuring "180° peel adhesive strength B".

[0049] A-4.Adhesive layer The above-mentioned cleaning sheet may include an adhesive layer. Any suitable material can be used as the material constituting such an adhesive layer, as long as it does not impair the effects of the present invention. Examples of materials for the adhesive layer include acrylic adhesives, silicone adhesives, rubber adhesives, urethane adhesives, and the like.

[0050] The adhesive layer is provided, for example, to be attached to the mirror surface of a dummy wafer. As a result, the cleaning sheet is attached to the dummy wafer, which acts as a transport member, and it can become a transport member with a cleaning function according to an embodiment of the present invention.

[0051] The adhesive layer has a 180° peel-off adhesive strength C, as defined in JIS-Z-0237, against the mirror surface of the dummy wafer, preferably 10 N / 10 mm or more, more preferably 15 N / 10 mm or more, even more preferably 20 N / 10 mm or more, particularly preferably 25 N / 10 mm or more, and most preferably 30 N / 10 mm or more. If the 180° peel-off adhesive strength C of the adhesive layer against the mirror surface of the dummy wafer, as defined in JIS-Z-0237, is within the above range, for example, the adhesion between the adhesive layer and the dummy wafer will be increased, making it difficult for the cleaning sheet to peel off the dummy wafer during cleaning.

[0052] The thickness of the adhesive layer is preferably 1 μm to 200 μm, more preferably 2 μm to 100 μm, even more preferably 3 μm to 80 μm, particularly preferably 4 μm to 60 μm, and most preferably 5 μm to 50 μm.

[0053] A-5. Protective film The cleaning sheet of the present invention may have a protective film to protect the cleaning layer, support, adhesive layer, etc. The protective film can be peeled off at an appropriate stage.

[0054] Any suitable material can be used as the material constituting the protective film, as long as it does not impair the effects of the present invention. Examples of materials for the protective film include polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene and other polyolefins, polyvinyl chloride, vinyl chloride copolymers, polyethylene terephthalate, polybutylene terephthalate, polyurethane, ethylene vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, polystyrene, polycarbonate, polyimide, and fluororesin.

[0055] The protective film may be subjected to any appropriate delamination treatment, provided that it does not impair the effects of the present invention. Typically, the delamination treatment is performed using a delaminating agent. Examples of delaminating agents include silicone-based delaminating agents, long-chain alkyl-based delaminating agents, fluorine-based delaminating agents, fatty acid amide-based delaminating agents, and silica-based delaminating agents.

[0056] The thickness of the protective film is preferably 1 μm to 100 μm.

[0057] The method for forming the protective film is appropriately selected according to the purpose, and can be formed by methods such as injection molding, extrusion molding, or blow molding.

[0058] B. Method for manufacturing cleaning sheets As a method for manufacturing a cleaning sheet according to an embodiment of the present invention, any suitable manufacturing method can be adopted as long as it does not impair the effects of the present invention. For example, such a manufacturing method involves casting the cleaning layer-forming composition (varnish) containing the polyamic acid onto a support, uniformly forming a film with a spin coater or the like, and then heating to directly form a cleaning layer on the support. Preferably, a cleaning sheet according to an embodiment of the present invention is manufactured by coating the support with the cleaning layer-forming composition (varnish) using a spin coater to form a film, allowing it to stand as necessary, and heating and / or drying as necessary to form a cleaning layer on the support. The cleaning layer-forming composition (varnish) may be prepared by mechanical synthesis or by manual synthesis. The cleaning layer-forming composition (varnish) is preferably prepared in a clean environment, for example, by mechanical synthesis. Even if manual intervention is involved, such as preparing the composition by adding raw materials to a flask and stirring (for example, stirring with a stirring blade), it is preferable to employ a highly clean operation.

[0059] In one embodiment, the method for manufacturing the cleaning sheet includes a step of measuring the Na concentration or Ca concentration in the cleaning layer forming composition (varnish). In embodiments of the present invention, by measuring the Na concentration or Ca concentration in the cleaning layer forming composition (varnish), errors during varnish preparation (e.g., human intervention) can be detected simply and with high accuracy. As a result, a cleaning layer in which metal contamination is prevented can be formed.

[0060] In one embodiment, the Na concentration in the cleaning layer-forming composition (varnish) is 10 ppm or less, preferably 8 ppm or less, and more preferably 6 ppm or less. Within this range, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. The lower the Na concentration in the cleaning layer-forming composition (varnish), the better, with a lower limit of, for example, 1 ppm (preferably 0 ppm). A cleaning layer-forming composition (varnish) with low Na concentration and the Ca concentration described later can be obtained, for example, by preparing it in a clean environment as described above. Alternatively, the cleaning layer-forming composition (varnish) may be prepared in a Class 1 to Class 10 (ISO 14644-1) cleanroom. The Na concentration and the Ca concentration described later in the cleaning layer-forming composition (varnish) can be measured by ion chromatography. Specifically, a predetermined atomic absorption spectrophotometer (for example, Shimadzu Corporation's "AA-7000") can be used to measure the Na and Ca concentrations based on a calibration curve created using standard solutions for each measurement target.

[0061] In one embodiment, the Ca concentration in the cleaning layer-forming composition (varnish) is 10 ppm or less, preferably 8 ppm or less, and more preferably 6 ppm or less. Within this range, a cleaning sheet with excellent cleanliness that can prevent contamination originating from the cleaning layer can be obtained. The lower the Ca concentration in the cleaning layer-forming composition (varnish), the better, and its lower limit is, for example, 1 ppm (preferably 0 ppm).

[0062] In one embodiment, the Na concentration and Ca concentration in the cleaning layer-forming composition (varnish) are preferably 10 ppm or less, more preferably 8 ppm or less, and even more preferably 6 ppm or less.

[0063] The viscosity of the cleaning layer-forming composition (varnish) is preferably 100 mPa·s to 4000 mPa·s, more preferably 300 mPa·s to 3000 mPa·s, and even more preferably 500 mPa·s to 2000 mPa·s.

[0064] The rotation speed when applying the cleaning layer-forming composition (varnish) using a spin coater to form a film is preferably 400 rpm or higher, more preferably 600 rpm or higher, and even more preferably 800 rpm or higher. The upper limit of the above rotation speed is preferably 3000 rpm or lower, in order to better exhibit the effects of the present invention.

[0065] The rotation time when applying the cleaning layer-forming composition (varnish) using a spin coater to form a film is preferably 5 seconds to 200 seconds, more preferably 10 seconds to 150 seconds, and even more preferably 20 seconds to 60 seconds.

[0066] In the method for manufacturing a cleaning sheet according to an embodiment of the present invention, the cleaning layer-forming composition (varnish) is applied to a support to form a film, and then left to stand, which can further smooth the varnish. The standing time is preferably 5 to 1000 seconds, more preferably 30 to 600 seconds, and even more preferably 100 to 400 seconds.

[0067] In the method for producing a cleaning sheet according to an embodiment of the present invention, a cleaning layer-forming composition (varnish) may be applied to form a film, and then heated and / or dried. The heating or drying temperature is preferably 50°C to 200°C, more preferably 80°C to 150°C. The heating or drying time is preferably 100 seconds to 900 seconds, more preferably 300 seconds to 900 seconds, and even more preferably 600 seconds to 900 seconds.

[0068] In the method for manufacturing a cleaning sheet according to an embodiment of the present invention, a cleaning layer-forming composition (varnish) may be applied to form a film, heated and dried, and then cured under a vacuum or nitrogen atmosphere. The curing temperature is preferably 200°C to 400°C, more preferably 250°C to 350°C. The heating or drying time is preferably 30 minutes to 300 minutes, more preferably 60 minutes to 200 minutes. In this curing process, the cleaning resin is heated above its glass transition temperature, which softens it, improves its conformability to the wafer surface, and improves the adhesion between the wafer and the cleaning layer.

[0069] C. Conveyor components with cleaning function A transport member with a cleaning function according to an embodiment of the present invention comprises the above-mentioned cleaning sheet and transport member.

[0070] Figure 4 is a schematic cross-sectional view showing one embodiment of the cleaning function transport member of the present invention. In Figure 4, the cleaning function transport member 300 includes a cleaning sheet 100 and a transport member 200. If the cleaning sheet 100 has an adhesive layer, preferably the outermost layer of the cleaning sheet 100 on the transport member 200 side is the adhesive layer.

[0071] As the transport member, any suitable transport member can be used as long as it does not impair the effects of the present invention. Examples of such transport members include semiconductor wafers (e.g., silicon wafers), substrates for flat panel displays such as LCDs and PDPs, compact disks, and MR heads. Among these transport members, when the purpose is to clean the wafer transport device within a substrate processing apparatus, a typical example is a semiconductor wafer (e.g., a silicon wafer). [Examples]

[0072] The present invention will be described more specifically below with reference to examples and comparative examples. However, the present invention is not limited in any way to these. In the following description, "parts" and "%" refer to weight unless otherwise specified.

[0073] [Example 1] (Manufacturing of polyimide varnish) Polyimide varnish was prepared by mechanical synthesis. Specifically, 57.0 g of 4,4'-diaminediphenyl ether and H2N-CH(CH3)-(O-CH2-CH(CH3)) were mixed in a separable flask equipped with a stirring device. n 92g of -NH2 (product name "BaxxodurEC-303", manufactured by BASF, molecular weight 2000, n=approx. 33) and 1000g of dimethylacetamide were charged and stirred at room temperature until the 4,4'-diamine diphenyl ether EC303 was completely dissolved. Then, 72g of pyromellitic anhydride was slowly added over 10 minutes, stirred at room temperature for 1 hour, and then heated to 70°C and stirred for 4 hours to obtain polyimide varnish (1). The viscosity of the obtained polyimide varnish (1) was 1500 mPa·s. (Manufacturing and evaluation of a transport component with a cleaning function and a cleaning layer) The obtained polyimide varnish (1) was applied to the mirror surface of a 12-inch silicon wafer using a spin coater (Tokyo Electron, ACT-12, rotation speed = 1000 rpm, rotation time = 30 seconds), left to stand for 300 seconds, heated at 100°C for 2 minutes to remove N-methyl-2-pyrrolidone, and then heated under vacuum at 280°C for 2 hours to obtain a transport member with a cleaning function having a cleaning layer with a thickness of 7.0 μm. The transport member with a cleaning function has a cleaning sheet made of the cleaning layer and a silicon wafer as the transport member. The resulting transport member with cleaning function was subjected to the following evaluation. The results are shown in Table 1.

[0074] <Rating> (1) Amount of metal transferred to silicon wafer On the surface of the cleaning layer of the obtained cleaning sheet, the silicon wafer (surface metal content measurement using total internal reflection X-ray fluorescence analysis showed that Ti, Cr, Mn, Ni, Fe, Co, Cu, and Zn were present in 1 × 10⁻¹⁶ layers) 10 atoms / cm 2The following materials were bonded together (bonding conditions: one pass-through with a 3kg hand roller), and then the silicon wafer was peeled off. The amount of transferred metal on the surface attached to the cleaning layer was measured by total internal reflection X-ray fluorescence analysis. Ti, Cr, Mn, Ni, Fe, Co, Cu, and Zn were measured under the following conditions. As shown in Table 1, all atoms were below the detection limit. Equipment: Technos TREX 630III X-ray source: W-type sealed tube X-ray source, 40kV, 40mA Measurement time: 500sec (2) Amount of Na and Ca in the cleaning layer 100 mg of the cleaning layer was collected in a Teflon® container, acid was added, and the container was sealed tightly. This container was irradiated with microwaves and pressurized acid decomposition was performed at 220°C. Then, ultrapure water was added to bring the volume to 20 ml, and the amount of Na and Ca in the cleaning layer was measured by ICP-MS under the following conditions. Disassembly equipment: CEM MARS5 Measurement device: Agilent Technologies 8800 (3) Indentation modulus of the cleaning layer The indentation modulus of the cleaning layer was measured using a nanoindenter under the following conditions: frequency 100 Hz, indentation depth 100 nm, measurement sample size 1.0 cm × 1.0 cm, and amplitude 2 nm. (Measurement device and measurement conditions) Device: Tribo Indenter manufactured by Hysitron Inc. Indenter used: Berkovich (triangular pyramid type) Measurement method: Single indentation measurement Indentation depth setting: 100nm Frequency: 100Hz Amplitude: 2nm Measurement atmosphere: Nitrogen atmosphere Sample size: 1cm x 1cm (4) Cleanability The mirror surface of a 6-inch silicon wafer was left in the air for 6 hours to contaminate it, and the number of foreign particles on the mirror surface was measured (Count 1). Next, the mirror surface of the contaminated 6-inch silicon wafer was attached to a cleaning sheet, then peeled off, and the number of foreign particles on the mirror surface of the silicon wafer after peeling was measured (Count 2). The dust removal performance was calculated using the following formula. Dust removal performance (%)=[(Count1-Count2) / Count1]×100 Based on the dust removal properties described above, the cleaning performance was evaluated according to the following criteria. ◎(Excellent): Dust removal performance of 70% or more ○ (Good): Dust removal performance is 50% or more but less than 70%. △ (Acceptable): Dust removal efficiency is 20% or more but less than 50% × (Not acceptable): Cleaning layer adheres to the mirror surface / Dust removal efficiency is less than 20%

[0075] [Table 1] [Industrial applicability]

[0076] The cleaning sheet and the transport member with cleaning function of the present invention are suitably used for cleaning substrate processing equipment such as various manufacturing and inspection devices. [Explanation of Symbols]

[0077] Cleaning sheets 100 Cleaning layer 10 Protective film 20 Adhesive layer 30 Support 40 Conveyor component with cleaning function 300 Conveying component 200

Claims

1. Equipped with a cleaning layer, The cleaning layer contains a polyimide resin, The amount of metal transferred to the silicon wafer by total internal reflection X-ray fluorescence analysis was 1 × 10⁻⁶. １１ atoms / cm ２ The following is: Cleaning sheet.

2. The amount of Ca transferred to the silicon wafer by total internal reflection X-ray fluorescence analysis of the cleaning layer is 1 × 10 １１ atoms / cm ２ The cleaning sheet according to claim 1, which is as follows:

3. The cleaning sheet according to claim 1, wherein the amount of metal in the cleaning layer is 10 ppm or less.

4. The cleaning sheet according to claim 1, wherein the amount of Na and Ca in the cleaning layer is both 10 ppm or less.

5. The cleaning sheet according to claim 1, wherein the indentation modulus of the cleaning layer at 25°C is 0.1 GPa to 2 GPa.

6. The cleaning sheet according to claim 1, further comprising a support disposed adjacent to the cleaning layer.

7. A conveying member with a cleaning function, comprising the cleaning sheet and conveying member described in claim 1.

8. This includes coating a support with a cleaning layer-forming composition. The Na concentration and Ca concentration in the cleaning layer forming composition are both 10 ppm or less. A method for manufacturing cleaning sheets.

9. The method for producing a cleaning sheet according to claim 8, further comprising the step of measuring the Na concentration or Ca concentration in the cleaning layer forming composition.

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