Composition for temporary fixation

Abstract

This invention relates to a composition for temporary fixation, characterized by containing the following (A) to (C), and having a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 500 to 10000 mPa·s at atmospheric pressure. (A) A monofunctional (meth)acrylate having a surface tension at 23°C measured by the ds / de method based on the pendant drop method in the range of 20 to 30 mN / m; (B) A polyfunctional (meth)acrylate having a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 1000 mPa·s or more at atmospheric pressure, or being a solid at 23°C, or having a molecular weight of 500 or more and a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 100 mPa·s or more but less than 1000 mPa·s at atmospheric pressure; (C) A photoradical polymerization initiator.

Description

Composition for temporary fixation This invention relates to a composition for temporary fixation. In the manufacture of electronic devices, wafer-type substrates with a thickness of several hundred μm are frequently used. These are obtained by using inorganic materials, such as silicon, as the substrate and performing processes such as insulating film formation, circuit formation, and thinning by grinding on their surface. However, most substrates are brittle and easily broken, so measures to prevent breakage are needed, especially during thinning by grinding. Previously, a method was used to attach a temporary protective tape that could be peeled off after the processing to the opposite side (also known as the back side) of the surface being ground. This tape uses an organic resin film as its base material, which is flexible but lacks sufficient strength or heat resistance, making it unsuitable for use in high-temperature processes. Therefore, a system is proposed that provides sufficient durability to withstand the conditions of back-side grinding or back-side electrode formation processes by bonding electronic device substrates to supports such as silicon or glass via adhesive. Here, the adhesive layer used to bond the substrate to the support is crucial. This adhesive layer needs to bond the substrate to the support without gaps, possess sufficient durability to withstand subsequent processes, and ultimately allow for easy and temporary fixation of the thinned wafer by peeling it easily from the support. In the processing of this type of wafer, the main processes include spin coating; vacuum bonding and photocuring; thinning by grinding and polishing; high-temperature processing; laser stripping; and removal of temporary fixatives. In the spin coating process, the temporary fixative needs to have a suitable viscosity and be a Newtonian fluid (or have shear viscosity that is not shear rate dependent) in order to form a film of the temporary fixative uniformly on the wafer. In vacuum bonding / UV curing processes, a temporary fixative is needed that can be cured on a support such as glass by irradiation with ultraviolet (UV) light for a short time, and produce less gas release (low gas release). In thinning processes using grinding and polishing, a temporary fixing agent is required to have a suitable hardness that disperses the load in the in-plane direction and prevents localized sinking of the substrate while maintaining its planarity, thus avoiding damage caused by the localized application of the grinding machine load to the substrate. In addition, it also requires adhesion to the support, an appropriate modulus of elasticity to protect the edges, and chemical resistance. In high-temperature processing, temporary fixatives are required to have heat resistance that can withstand prolonged high-temperature processing in a vacuum (e.g., at temperatures above 300°C for more than 1 hour). In the laser stripping process, a temporary fixative is required that can be stripped at high speed by lasers such as UV lasers. In the removal process, in addition to the ease of peeling so that the substrate can be easily peeled off from the support, it is also necessary to have the properties of preventing adhesive residue from remaining on the substrate after peeling and to have easy cleaning properties. In light of this background, for example, Patent Document 1 discloses a temporary fixation composition comprising: (A-1) a monofunctional (meth)acrylate having alkyl side chains having 18 or more carbon atoms and a Tg of -100°C to 60°C for the homopolymer; (A-2) a polyfunctional (meth)acrylate; (B) a polyisobutylene polymer and / or a polyisobutylene copolymer; and (C) a photoradical polymerization initiator, which is said to have excellent heat resistance, low gas release, and peelability. [Prior Art Documents] [Patent Documents] [Patent Document 1] International Publication No. 2021 / 235406 [The problem the invention aims to solve] When applying a temporary fixative based on prior art to a wafer via spin coating, it has been reported that bubbles are generated within the temporary fixative and directly encapsulated. Since these bubbles adversely affect the physical properties, mitigation of this phenomenon is required. [Technical Means for Solving the Problem] The inventors have elucidated the mechanism by which the air bubbles are incorporated and devised a mechanism to eliminate them. Specifically, the present invention provides the following configuration. Sample 1. A composition for temporary fixation, characterized by containing the following (A) to (C), and having a shear rate of 1 s at 23°C as measured by a rotational rheometer. -1 The viscosity at atmospheric pressure is in the range of 500–10000 mPa·s; (A) monofunctional (meth)acrylates, with a surface tension of 20–30 mN / m at 23°C as determined by the ds / de method based on the pendant drop method; (B) polyfunctional (meth)acrylates, with a surface tension of 20–30 mN / m at 23°C and a shear rate of 1 s⁻¹ as determined by a rotational rheometer. -1 The viscosity at atmospheric pressure is 1000 mPa·s or higher, or it is a solid at 23°C, or it has a molecular weight of 500 or higher and a shear rate of 1 s⁻¹ at 23°C as measured by a rotational rheometer. -1 The viscosity at atmospheric pressure is above 100 mPa·s but below 1000 mPa·s (C) Photoradical polymerization initiator. Sample 2. The composition for temporary fixation as described in Sample 1, wherein the amount of component (A) is in the range of 5% to 65% in the mass ratio of component (A) to component (B). Sample 3. A temporary fixation composition as described in Sample 1 or 2, wherein component (A) is an aliphatic monofunctional (meth)acrylate. State 4. The temporary fixation composition as described in State 3, wherein the aliphatic group of component (A) has 6 to 30 carbons. 5. A composition for temporary fixation as described in any one of 1 to 4, wherein component (B) comprises an oligomer or a polymer. Sample 6. The temporary fixation composition described in any one of Samples 1 to 5 further comprises the following (D): (D) UV absorber. Sample 7. A hardening body, which is a hardening body of the temporary fixation composition described in any one of Samples 1 to 6. State 8. The hardened body as described in State 7 has a 2% mass reduction temperature of 300°C or higher under a nitrogen atmosphere. 9. A method for manufacturing a substrate for an electronic device, comprising the following steps: mixing a monofunctional (meth)acrylate, a polyfunctional (meth)acrylate, and a photoradical polymerization initiator to prepare a composition with a viscosity in the range of 500 to 10000 mPa·s at 23°C; coating the prepared composition onto a silicon wafer by spin coating to achieve a flatness with a height difference of only 40 μm or less on the surface of the coated composition; and attaching a support to the silicon wafer in a manner that separates the coated composition from the substrate. Sample 10. A temporary fixation adhesive comprising the temporary fixation composition as described in any one of Samples 1 to 6. Sample 11. An adhesive comprising a temporary fixing adhesive as described in Sample 10, and a substrate bonded by the temporary fixing adhesive. Sample 12. A method for manufacturing a thin wafer, wherein the temporary fixing adhesive as described in Sample 10 is used. [Effects of the Invention] According to the present invention, a novel composition is obtained that can reduce air bubble ingress in the spin coating process during the manufacture of electronic devices. In this specification, unless otherwise stated, numerical ranges include both upper and lower limits. In this specification, a monofunctional (meth)acrylate refers to a compound having one (meth)acrylic group per molecule. A polyfunctional (meth)acrylate refers to a compound having two or more (meth)acrylic groups per molecule. An n-functional (meth)acrylate refers to a compound having n (meth)acrylic groups per molecule. The polymerizable functional group in a polyfunctional (meth)acrylate may contain only an acrylonitrile, only a methacrylic group, or both an acrylonitrile and a methacrylic group. In embodiments of the present invention, a temporary fixing composition (also referred to as a "temporary fixative") is provided, comprising (A) a monofunctional (meth)acrylate having specified properties, (B) a polyfunctional (meth)acrylate having specified properties, and (C) a photoradical polymerization initiator, and having a specified viscosity overall. The inventors discovered that in the coating process of applying a temporary fixative using spin coating during the manufacture of substrates for electronic devices, the temporary fixative on the substrate undergoes slight deformation due to centrifugal force caused by the rotation of the substrate. The degree of this slight deformation affects the presence or absence of air bubbles, leading to the development of this invention. In spin coating processes, it is known that centrifugal force can cause bulges (referred to as "edge beads") near the edges of the object. However, in the field of acrylate-based temporary fixatives comprising combinations of monofunctional (meth)acrylates and polyfunctional (meth)acrylates, the cause of these edge beads is unknown. Specifically, it has been found that if a combination of factors—the surface tension of the monofunctional (meth)acrylate, the viscosity of the polyfunctional (meth)acrylate, and the viscosity of the mixture—is not met, the edge beads become higher. Furthermore, if the height of the edge beads is less than 40 μm, air bubbles cannot easily enter when bonding the support to the wafer. This discovery solves the problem addressed in this invention. In this specification, the viscosity of the entire composition, measured by a rotational rheometer at 23°C (atmospheric pressure), is 1 s⁻¹. -1 The viscosity ranges from 500 to 10000 mPa·s. Preferably, the viscosity is 500 to 8000 mPa·s, more preferably 500 to 5000 mPa·s. If the overall viscosity of the composition is less than 500 mPa·s, its coatability is low and it cannot be used practically. Furthermore, if the overall viscosity of the composition exceeds 10000 mPa·s, the viscosity is too high and unsuitable for spin coating. Also, in this specification, the viscosity of component (B) below is measured in the same manner as described above. The monofunctional (meth)acrylate contained in this composition as component (A) is characterized by a surface tension of 20–30 mN / m at 23°C, measured using the ds / de method based on the pendant drop method. Although this is hypothetical, it is speculated that if the surface tension of component (A), which plays a role in forming a relatively soft framework in the composition, is within a narrow and specific range, it will not easily deform due to centrifugal force through its interaction with component (B). Furthermore, the ds / de method is a technique for measuring the maximum diameter (equatorial diameter) of a pendant drop formed using the pendant drop method, and the diameter ds of the drop at the point where it rises only from its lowest point (de). The surface tension γ is then calculated using the following formula: γ = ρg(de). 2 In the formula (1 / H), ρ is the density, g is the gravitational acceleration, and 1 / H is the correction term obtained from ds / de. The ds / de method is known, for example, from the following literature: https: / / www.scas.co.jp / technical-informations / technical-news / pdf / tn142.pdf (A) The type of component can be selected based on the ds / de method. When component (A) contains two or more monofunctional (meth)acrylates, the surface tension of the mixture of the two or more monofunctional (meth)acrylates can be measured to determine the surface tension. Furthermore, the overall surface tension of the composition can be measured in the same manner as when component (A) is used alone, preferably in the range of 28–33 mN / m at 23°C. Although this is an assumption, it is believed that the surface tension of the composition is directly proportional to the height of the edge beads described below. (A) is preferably an aliphatic monofunctional (meth)acrylate. The number of carbon atoms in its aliphatic group can be 6 to 30, more preferably 8 to 20. Although this is hypothetical, it is speculated that if (A) is a component with moderately strong hydrophobicity, the aforementioned surface tension effect is easily obtained. Furthermore, it is believed that highly polar monofunctional (meth)acrylates such as acrylmorpholine typically have excessively high surface tension and are therefore unsuitable. In the mass ratio of component (A) to component (B), the amount of component (A) is preferably in the range of 5% to 65%, more preferably 5% to 60%, and even more preferably 10% to 50%. The polyfunctional (meth)acrylate contained in this composition as component (B) is characterized by a shear rate of 1 s at 23°C, as measured by a rotational rheometer. -1 The viscosity at atmospheric pressure is 1000 mPa·s or higher, or it is a solid at 23°C, or it has a molecular weight of 500 or higher and a shear rate of 1 s⁻¹ at 23°C as measured by a rotational rheometer. -1 The viscosity at atmospheric pressure is 100 mPa·s or more but less than 1000 mPa·s (preferably 120 mPa·s or more but less than 1000 mPa·s). Furthermore, regarding the statement above, "...at 23°C...viscosity at atmospheric pressure is 1000 mPa·s or more, or is a solid at 23°C," the latter essentially constitutes a description of the upper limit of viscosity (i.e., being a solid can also be interpreted as having very high viscosity). Therefore, it should be noted that although the statement above, "...at 23°C...viscosity at atmospheric pressure is 1000 mPa·s or more," does not specify an upper limit, it is technically clear. While not wishing to be bound by a specific theory, it is speculated that by combining component (B), which has this viscosity or molecular weight or is solid at room temperature, with component (A) as described above, the alkyl groups of component (A) are exposed on the surface with their molecular sides facing outwards, thereby reducing edge beads. The type of component (B) can be selected based on viscosity measurement methods. When component (B) contains two or more polyfunctional (meth)acrylates, the viscosity of the mixture of the two or more polyfunctional (meth)acrylates can be measured to determine its composition. (B) The components may be monomers, or may include oligomers or polymers. The photoradical polymerization initiator (C) contained in this composition refers to a substance that can initiate the free radical polymerization of components (A) and (B) upon exposure to light. For example, it refers to a compound whose molecules break down into two or more free radicals upon exposure to ultraviolet or visible light (e.g., wavelengths of 350 nm to 700 nm, preferably 365 nm to 500 nm, more preferably 385 nm to 450 nm). Examples of photoradical polymerization initiators include: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(η... 5 -2,4-Cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)-phenyl)titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholino-4-ylphenyl)-butane-1-one, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-O-benzoyl oxime, and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]acetone 1-(O-acetylgoxyme). (C) The ingredient may contain one or more of the above, or may contain a combination of two or more of them. Preferably, component (C) may contain a phosphine oxide compound. Examples of preferred phosphine oxide compounds include one or more selected from the group consisting of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. As a photoradical polymerization initiator, it is preferred to have excellent deep curing properties due to high sensitivity and photofading properties; furthermore, it is preferred to have an absorption wavelength region for generating free radicals extended to a relatively long wavelength region. The absorption wavelength region of the aforementioned preferred compound is in the range of at most about 440 nm, which is significantly different from the absorption wavelength region of the UV absorber used in the UV laser stripping process described below. That is, the degree of UV curing inhibition obtained using the UV absorber is smaller, and free radical polymerization can be initiated with longer wavelength light. Therefore, even in the presence of a UV absorber, a relatively fast and efficient initiation of free radical polymerization for curing can be achieved. In a preferred embodiment, the photoradical polymerization initiator can be selected based on absorbance. Specifically, the photoradical polymerization initiator can be selected from one or more compounds that meet any one or more of the following conditions: when dissolved at a concentration of 0.1% by mass in a solvent (e.g., acetonitrile or toluene) that does not have extremely high absorption in the wavelength region of 300 to 500 nm, the absorbance is 0.5 or more at a wavelength of 365 nm, the absorbance is 0.5 or more at a wavelength of 385 nm, and the absorbance is 0.5 or more at a wavelength of 405 nm. Examples of compounds that satisfy these conditions include: 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetylgoxime) with an absorbance of 0.5 or more at 365 nm when dissolved in acetonitrile as a solvent at a concentration of 0.1% by mass; 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-O-benzoyl oxime with an absorbance of 0.5 or more at wavelengths of 365 nm and 385 nm; and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide with absorbances of 0.5 or more at wavelengths of 365 nm, 385 nm and 405 nm. Furthermore, considering both the hardening properties brought about by photoradical polymerization initiators and UV laser exfoliation, a double (η) polymer with an absorption wavelength region in the 400–500 nm range is suitable. 5 -2,4-Cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)-phenyl)titanium can also be used as a photoradical polymerization initiator. As a photoradical polymerization initiator (C), in terms of reaction rate, heat resistance after curing, low gas release, and absorption characteristics in a region different from the wavelength of the UV laser used for UV laser stripping and the absorption wavelength region of the UV absorber used for UV laser stripping, it is preferably selected from one or more phosphine oxide compounds, dicene compounds, or α-amine alkyl phenyl ketone compounds. Furthermore, as a photoradical polymerization initiator for a resin composition used for temporary fixation purposes and not for the UV laser stripping process in a temporary fixation composition having the following structure, in addition to the above, oxime ester compounds may also be selected, wherein the temporary fixation purpose refers to preventing breakage from the bonding of the workpiece substrate and the support substrate until the heating process. Examples of phosphine oxide compounds include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Among these, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is particularly preferred. Examples of bis(η) titanium compounds include: 5 -2,4-Cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrolo-1-yl)-phenyl)titanium. Examples of α-amine alkyl phenyl ketone compounds include: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholino-4-yl-phenyl)-butane-1-one, etc. Examples of oxime ester compounds include 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-O-benzyl oxime and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetylgoxime). Among these, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetylgoxime) is preferred. Regarding the reaction rate, heat resistance after curing, and low gas release, the amount of photoradical polymerization initiator (C) used relative to the total of 100 parts by mass of components (A) and (B) is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 1 part by mass. If component (C) is 0.01 parts by mass or more, sufficient curing properties can be obtained; if it is 5 parts by mass or less, the effects of low gas release and minimal damage to heat resistance can be achieved. This composition may also include a UV absorber as component (D). A UV absorber refers to a compound whose molecules break down and decompose or vaporize due to laser irradiation by ultraviolet or visible light, and such decomposition or vaporization occurs at the interface between the support substrate (or support) and the temporary fixative, thereby causing the loss of adhesion between the temporary fixative and the support substrate (or support) maintained until the upcoming peeling process. As a (D)UV absorber, in terms of the degree of overlap between the UV absorption wavelength region and the UV laser wavelength, the UV absorption characteristics at the same wavelength, low gas release, and heat resistance, it is preferably selected from one or more of benzotriazole compounds, benzophenone compounds, and hydroxyphenyltriazole compounds. As a benzotriazole compound, in terms of compatibility with resin components, UV absorption characteristics, low gas release, and heat resistance, it is particularly preferred to be selected from one or more of the group consisting of 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2,2'-methylenebis[6-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimide-methyl)-5-methylphenyl]benzotriazole, and 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole. As a hydroxyphenyl triterpenoid compound, in terms of compatibility with components (A) and (B), UV absorption characteristics, low gas release, and heat resistance, it is particularly preferred to be selected from one or more of the group consisting of 2-[4-[(2-hydroxy-3-(2'-ethylhexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triterpenoid, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-bis-butoxyphenyl)-1,3,5-triterpenoid, and 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triterpenoid. As a benzophenone compound, in terms of compatibility with components (A) and (B), UV absorption characteristics, low gas release, and heat resistance, it is particularly preferred to be selected from one or more of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-diacryloxybenzophenone, and hydroxybenzophenone compounds. In a preferred embodiment for use in a UV laser stripping process, the preferred UV absorber is one or more selected from the group consisting of 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-tris(2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-bis-butoxyphenyl)-1,3,5-tris(2,4-bis-butoxyphenyl)-1,3,5-tris(2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol]. These absorbers exhibit excellent compatibility with component (A), have a high melting point, and relatively low vapor pressure at temperatures below approximately 300°C. Therefore, the dosage can be selected over a wide range, and this helps reduce gas release from the temporarily fixed composition after curing at these temperature conditions. As a (D) UV absorber, the best choice is to use absorbers selected based on UV transmittance, as exemplified below. By giving the (D) component this UV transmittance, the curing and peeling of the composition can be properly controlled. When the UV absorber is dissolved at a concentration of 0.002% by mass in a solvent that does not exhibit significant absorption at wavelengths of 290–410 nm, it is preferable that the transmittance at a wavelength of 355 nm is less than 50% within an optical path length of 1 cm, and that the transmittance is greater than 50% at wavelengths of 385–420 nm. More preferably, the transmittance is less than 40% at a wavelength of 355 nm, and that the transmittance is also greater than 60% at wavelengths of 385–420 nm. As a preferred (D)UV absorber from the viewpoint of transmittance under the above conditions, the following can be cited as examples: 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole (RUVA-93 manufactured by Otsuka Chemical Co., Ltd., molecular weight 323.0), 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (Tinuvin 900 manufactured by BASF, Adekastab LA-24 manufactured by ADEKA, EVERLight Chemical's EVERORB 76 / EVERSORB 234, molecular weight 447), 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (Tinuvin 928 manufactured by BASF, EVERLight Chemical's EVERORB). 89 / 89FD (molecular weight 442), 2-[4-[(2-hydroxy-3-(2'-ethylhexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-tris(BASF Tinuvin 405, molecular weight 584), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-bis-butoxyphenyl)-1,3,5-tris(BASF Tinuvin 460, molecular weight 630). The UV transmittance of the cured body in this specification is a value obtained by reflectance measurement spectrophotometry. Specifically, the transmittance can be obtained using a reflectance spectrophotometer (V-650 manufactured by Nippon Spectrophotometer Co., Ltd.) on a film of cured body with a thickness of approximately 50 μm, which is made by sandwiching a sheet of PET (polyethylene terephthalate) resin, under the following conditions. Slot length: 10 mm; Metering mode: T (Transmittance); Measurement range: 450-200 nm; Data scan interval: 1 nm; UV / vis band width: 2.0 nm; Sensitivity: medium; Scan speed: 40 nm / min; Light source switching: 340 nm; Light source: D2 / WI; Filter switching: Step correction: baseline. The amount of the UV absorber as component (D) relative to 100 parts by mass of components (A) and (B) is preferably 0.01 to 5 parts by mass, more preferably 0.5 to 2.5 parts by mass. If it is 0.01 parts by mass or more, sufficient UV laser stripping speed can be obtained, and if it is 5 parts by mass or less, the effect of low gas release and minimal damage to heat resistance can be obtained. The weight-average molecular weight in this specification is a value converted from standard polystyrene obtained by gel permeation chromatography (GPC). Specifically, the weight-average molecular weight can be determined by using tetrahydrofuran as a solvent and a GPC system (SC-8010 manufactured by Tosoh Corporation) to create a calibration curve using commercially available standard polystyrene under the following conditions. Flow rate: 1.0 ml / min Set temperature: 40℃ Column composition: 1 "TSK guardcolumn MP(×L)" 6.0 mm ID×4.0 cm (manufactured by Tosoh Corporation), and 2 "TSK-GELMULTIPOREHXL-M" 7.8 mm ID×30.0 cm (theoretical plate count 16,000 plates) (manufactured by Tosoh Corporation), totaling 3 columns (theoretical plate count 32,000 plates). Sample injection volume: 100 μl (sample concentration 1 mg / ml) Infusion pressure: 39 kg / cm² 2 Detector: RI detector (Differential Refractive Index Detector) In one embodiment of the present invention, a cured body of the above composition is also provided. This curing can be performed using the following light source. When the cured body is formed into a cured film with a thickness of 50 μm, it is preferable to satisfy one or more of the following conditions, more preferably all of them. The following conditions can be satisfied, for example, by using a UV absorber: • The light transmittance of the cured film is 70% or more in the wavelength region of the light source used for curing, which is 395 nm or more. • The light transmittance of the cured film is 20% or more in the wavelength region of the light source used for curing, which is 385 nm or more but less than 395 nm. • The light transmittance of the cured film is 1% or less at the wavelength (355 nm) of the UV laser used for UV laser stripping. By satisfying these conditions, both a sufficiently high curing speed and a high UV laser stripping speed can be achieved practically. Furthermore, in addition to possessing both sufficiently high curing speed and UV laser stripping speed, it can also reduce the rate of mass loss under heating conditions after curing (or reduce the amount of gas released under high-temperature vacuum). Temporary fixatives with these properties are particularly suitable for use in high-temperature vacuum processes, including electrode formation using ion implantation, annealing, or sputtering, during the back-side processing after thinning. This composition can be used as a resin composition for temporary fixation, an adhesive for temporary fixation, an adhesive sheet, or an adhesive for temporary fixation in the manufacture of electronic devices. In this specification, the terms "temporary fixation composition," "temporary fixation resin composition," and "temporary fixation adhesive" are sometimes collectively referred to as "temporary fixative." When using this composition to bond the workpiece substrate to an optically transparent support substrate (or support), it is preferable to use an energy of 1 to 20,000 mJ / cm² in the visible light or ultraviolet region (wavelength or center wavelength preferably 350–405 nm, more preferably 365–405 nm, most preferably 385–405 nm). 2 Irradiation is performed in this manner. If the energy is 1 mJ / cm 2 The above will result in sufficient adhesion, if it is 20000 mJ / cm 2 The following properties result in excellent productivity and minimize the generation of decomposition products from photoradical polymerization initiators, thus suppressing gas release. In terms of productivity, adhesion, low gas release, and easy peeling, a value of 1000–10000 mJ / cm² is preferred. 2 . There are no particular limitations on the substrate bonded by this composition, but it is preferred that at least one substrate is a light-transmitting transparent substrate. Examples of transparent substrates include inorganic substrates such as crystal, glass, quartz, calcium fluoride, and magnesium fluoride; and organic substrates such as plastics. Among these, inorganic substrates are preferred in terms of versatility and the ability to achieve significant effects. Among inorganic substrates, it is preferred that one or more are selected from glass and quartz. This composition can be photocurable, thereby providing a cured body with excellent heat resistance and peelability. In one embodiment, the cured body of the composition of the present invention exhibits low gas release even when exposed to high temperatures, making it suitable for bonding, sealing, and coating various optical components or devices, and electronic components. The composition of the present invention is suitable for applications requiring durability in multiple aspects such as solvent resistance, heat resistance, and adhesion, and is particularly suitable for semiconductor manufacturing processes. The cured body of this composition can be used in processes over a wide temperature range, from room temperature to high temperatures. The heating temperature in the process is preferably below 350°C, more preferably below 300°C, and most preferably below 250°C. In a preferred embodiment, the temperature at which the mass reduction rate of the cured body is 2% can be above 250°C. Because the adhesive bonded by this composition has high shear adhesion, it can withstand thinning processes and can be easily peeled off after heating processes such as insulating film formation. When used at high temperatures, the cured body of this composition can be used, for example, in processes at preferably above 200°C, and more preferably above 250°C. In one embodiment, an adhesive is also provided that bonds a substrate by using the composition as an adhesive. The adhesive can be peeled off by applying external force. For example, it can be peeled off by inserting a knife, sheet, or filament into the joint. Alternatively, it can be peeled off by irradiating the optically transparent substrate side of the adhesive with a UV or IR laser in a full-surface scanning manner. <Method for Manufacturing Thin Wafers> In one embodiment, a method for manufacturing thin wafers is also provided. This method is characterized by using the aforementioned temporary fixing composition or temporary fixing adhesive (hereinafter sometimes simply referred to as adhesive or temporary fixing agent) as an adhesive layer between the wafer having semiconductor circuits and a support. This method for manufacturing thin wafers includes the processes described in (a) to (e). [Process (a)] Process (a) is the following process: when the circuit-forming surface of a wafer with a circuit-forming surface on the surface and a non-circuit-forming surface on the back is bonded to a support by an adhesive, an adhesive is applied to the support or the circuit-attached wafer by spin coating, and another support or circuit-attached wafer is bonded under vacuum. A wafer having a circuit forming surface and a non-circuit forming surface is a wafer with one side being the circuit forming surface and the other side being the non-circuit forming surface. The wafer to which this invention can be applied is typically a semiconductor wafer. Examples of such semiconductor wafers include not only silicon wafers, but also gallium nitride wafers, lithium tantalate wafers, lithium niobate wafers, silicon carbide wafers, germanium wafers, gallium-arsenic wafers, gallium-phosphorus wafers, gallium-arsenic-aluminum wafers, etc. The thickness of the wafer is not limited, but is preferably 600–800 μm, more preferably 625–775 μm. As a support, for example, a light-transmitting transparent substrate is used. [Process (b)] Process (b) is the process of photocuring the adhesive. After forming the above-mentioned wafer fabrication body (multilayer substrate), it is preferable to apply the adhesive at an energy of 1-20000 mJ / cm² in the visible light or ultraviolet region (wavelength or center wavelength preferably 350-405 nm, more preferably 365-405 nm, most preferably 385-405 nm). 2 Irradiation is performed in this manner. If the energy is 1 mJ / cm 2 The above will result in sufficient adhesion, if it is 20000 mJ / cm 2 The following properties result in excellent productivity, minimize the generation of decomposition products from the photoradical polymerization initiator, and suppress gas release. A value of 1000–10000 mJ / cm² is preferred in terms of productivity, adhesion, low gas release, and easy peeling. 2 . During the curing of the composition, a black light, UV-LED, or visible-LED can be used as the light source. For example, the following light sources can be used: As a black light, regardless of its center wavelength, a lamp containing components with a wavelength of 385 nm or higher is preferred. Furthermore, when a wavelength range is specified in this specification, whether it is included in that range is determined by whether the center wavelength is included within that range. • Black light (center wavelength 365 nm, illuminance 10 mW / cm²) 2 TOYO ADTEC Co., Ltd. manufactured TUV-8271 UV-LED (wavelength 385±5 nm, illuminance 350 mW / cm²). 2 (Conditions: Working distance from the front end of the mirror unit is 20 mm), HOYA's H-4MLH200-V2-1S19+ specially designed mirror unit) ･UV-LED (wavelength 395±5 nm, illuminance 375 mW / cm²) 2 (Conditions: Working distance from the front end of the mirror unit is 20 mm), HOYA Corporation's H-4MLH200-V3-1S19+ specially designed mirror unit) ･UV-LED (wavelength 405±5 nm, illuminance 400 mW / cm²) 2 (Conditions: Working distance from the front end of the mirror unit is 20 mm), HOYA Corporation's H-4MLH200-V4-1S19+ specially designed mirror unit) ･UV-LED (center wavelength 405 nm, illuminance 10 mW / cm²) 2 HLDL-120V0-NWPSC, manufactured by CCS Corporation, is a visible light LED (wavelength 451±5 nm, illuminance 550 mW / cm²). 2 (Conditions: Working distance from the front of the irradiation unit is 10 mm), HLDL-155VL450-PSC manufactured by CCS Corporation) • Visible light LED (wavelength 492±5 nm, illuminance 400 mW / cm²) 2 (Conditions: Working distance from the front of the irradiation unit is 10 mm), HLDL-155BG-PSC manufactured by CCS Corporation) In a preferred embodiment, since the irradiation wavelength is generally wider, UV-LEDs or visible-light LEDs, which require less cumulative light (and thus shorter irradiation time), can be used as the light source compared to black lights, which tend to have a longer irradiation time due to a larger cumulative light intensity. That is, by using an LED light source with a narrow irradiation wavelength band, temporary fixation can be achieved for a short period of time, resulting in a reduction in the time required for the manufacturing process. [Process (c)] Process (c) is a process of grinding and / or polishing the non-circuit-forming surface of the wafer bonded to the support, that is, a process of grinding the back side of the wafer fabrication body obtained in process (a) to reduce the thickness of the wafer. The thickness of the thinned wafer is preferably 10 to 300 μm, more preferably 30 to 100 μm. There are no particular limitations on the grinding / polishing method of the back side of the wafer, and a known grinding / polishing method is used. Regarding grinding, it is preferable to pour water onto the wafer and the grinding stone (such as a grinding stone with a diamond cutter) and perform grinding while cooling. [Process(d)] Process(d) refers to a wafer fabrication body that grinds / polishes the non-circuit-forming surfaces, i.e., the process of processing the non-circuit-forming surfaces of a wafer fabrication body that has been thinned by back-side grinding / polishing. This process includes various procedures used at the wafer level. Examples include electrode formation, metal wiring formation, and protective film formation. More specifically, previously known procedures include metal sputtering for forming electrodes, wet etching for etching sputtered metal layers, pattern formation using resist coating, exposure, and development to form a mask for metal wiring formation, resist stripping, dry etching, metal plating formation, silicon etching for forming TSVs, and oxide film formation on silicon surfaces. [Process (e)] Process (e) is a stripping process. This process involves stripping the wafer processed in process (d) from the wafer fabrication body. For example, it is a process of stripping the wafer from the wafer fabrication body after various processing is performed on a thinned wafer, before dicing. In this case, a dicing tape can be pre-attached to the thinned and processed surface. This stripping process is usually carried out at a relatively low temperature, from room temperature to about 60°C. As this stripping process, any one of the well-known UV laser stripping process, IR laser stripping process, or mechanical stripping process can also be used. UV laser stripping process refers to the following processes: for example, optical processes using self-made wafers. A UV laser is used to irradiate the entire surface of a wafer fabrication body in a tangential, reciprocating motion along one side. The laser energy decomposes the adhesive layer, causing it to peel off. This peeling process is described, for example, in Japanese Patent Publication No. 2019-501790 or Japanese Patent Publication No. 2016-500918. The IR laser lift-off process refers to a process in which the entire surface of a wafer is irradiated with an IR laser by scanning the optically transparent support side of the wafer in a straight line along the tangential direction. The laser energy heats and decomposes the adhesive layer, thereby lifting it off. This type of lift-off process is described, for example, in Japanese Patent No. 4565804. To implement this IR laser lift-off process, a photothermal conversion layer (e.g., 3M's LTHC, Light-To-Heat-Conversion release coating) that absorbs IR laser light and converts it into heat can be provided between the temporary fixative layer and the glass support. When using 3M's LTHC, for example, the LTHC is spin-coated onto the glass support and cured. Then, after the temporary fixative layer is spin-coated onto the wafer, it is bonded to the glass support with the LTHC layer and UV cured. A method for implementing an IR laser stripping process using 3M's LTHC is described, for example, in Japanese Patent No. 4565804, which is identical to the one described above. Mechanical peeling processes refer to processes that include, for example, inserting a scraper into the interface end of a wafer processing body to create a crack between the wafer and the support, with the wafer of the wafer processing body positioned horizontally and facing downwards. After the scraper is inserted, upward stress is applied to the support above and / or the scraper, causing the crack to develop and thereby peeling the wafer from the support. Such peeling processes are described, for example, in Japanese Patent No. 6377956 or Japanese Patent Application Publication No. 2016-106404. During the peeling of this composition, any of the peeling methods can be used. Preferably, one of the wafers or supports of the wafer processing body is horizontally fixed, and a peeling start point is formed by sizing with a squeegee or by using a solvent (e.g., aliphatic or aromatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, 1,3,5-trimethylbenzene, etc.) to swell the outer periphery of the adhesive layer. Then, the other wafer is lifted horizontally at a certain angle. These peeling methods are typically performed at room temperature, but heating to approximately 90°C is preferred. When using a laser, a YAG laser or a YVO laser is preferred. 4. Laser. When the process of peeling the wafer processed in step (e) above from the support is performed in the case of a mechanical peeling process, it is preferable to further include the following steps: (f) attaching a dicing strip to the wafer surface of the processed wafer; (g) vacuum adsorbing the dicing strip surface onto an adsorption surface; and (h) peeling the support from the processed wafer at a temperature range of 10 to 100°C on the adsorption surface. This facilitates the peeling of the support from the processed wafer and makes subsequent dicing processes easier. Furthermore, when using UV or IR lasers for peeling, the manufacturing method preferably includes, for example, the following processes: (i) placing / fixing the optically transparent support side of the processed wafer upwards in a horizontal location, preferably via a dicing strip; (j) irradiating the entire surface of the wafer using a scanning laser from the support side of the processed wafer. This facilitates the easy peeling of the support from the processed wafer and allows for easier subsequent dicing processes. Furthermore, after the wafer processed in step (e) is peeled off from the support using UV or IR laser, the following process is required: (k) Removal of the temporary fixative remaining on the wafer surface. Methods for removing the temporary fixative include: applying an adhesive tape, such as a wafer slicing tape, to the entire surface of another wafer containing the remaining temporary fixative while the wafer is vacuum-adsorbed onto the adsorption surface, and peeling off the tape along with the temporary fixative; and immersing the wafer in a solvent (e.g., pentane, hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, 1,3,5-trimethylbenzene, etc., aliphatic or aromatic hydrocarbon solvents) to swell the adhesive layer and then peeling it off. Among these methods, the tape peeling method is preferable in terms of fewer steps and shorter processing time. After removing the temporary fixative, the wafer can proceed directly to the next process without cleaning the surface. In the case of cleaning, it is preferable to proceed with the following process: (l) With the support and the wafer after removing the temporary fixative facing upwards, clean them with a solvent (e.g., aliphatic or aromatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, 1,3,5-trimethylbenzene). During process (k), some adhesive (temporary fixative) may remain on the circuit formation surface of the wafer after the temporary fixative has been removed. Furthermore, the stripped support is preferably cleaned and reused, and sometimes adhesive residue is also adhered to the surface of the support. Methods for removing such adhesive residue include immersion in a solvent (e.g., aliphatic or aromatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, benzene, toluene, xylene, 1,3,5-trimethylbenzene, etc.) to swell and then stripping. In one embodiment, various methods described below can be used to harden the above composition to obtain a hardened body. As a first method, a layer containing a temporary fixation composition with the above-mentioned components can be hardened to obtain a single-layer hardened body. Then, as a second method, the following method can be exemplified: A first layer containing a temporary fixing composition of at least components (A) to (C) and excluding a UV absorber as component (D), and a second layer containing a temporary fixing composition of at least components (A) to (D), are prepared and cured to obtain an integrated cured body having one or more layers. In this cured body, it is preferable that the concentration distribution of the components differs along its thickness direction, or that the concentration distribution of the components differs on the upper and lower surfaces along the thickness direction of the cured body. The difference in component concentration distribution can be confirmed by quantitatively measuring the UV transmittance of both sides of the cured body using the aforementioned reflectance measurement spectrophotometry. By combining layers with different transmittance using this method, an optimal curing effect can be achieved. Furthermore, during the above curing process, a black light lamp or a UV-LED (the method described below is also applicable) can be used as the light source. As an example of a black light, one could cite the TUV-8271 manufactured by TOYO ADTEC Co., Ltd. (center wavelength 365 nm, illuminance 10 mW / cm²). 2 Furthermore, as for UV-LEDs, an example is the H-4MLH200-V2-1S19+ specially designed mirror unit manufactured by HOYA Co., Ltd. (wavelength 385±5 nm, illuminance 350 mW / cm²). 2 Conditions: Scanning distance from the front of the mirror unit 20 mm; HOYA Co., Ltd. H-4MLH200-V3-1S19+ dedicated mirror unit (wavelength 395±5 nm, illuminance 375 mW / cm²). 2 Conditions: Working distance from the front end of the mirror unit is 20 mm; HOYA Co., Ltd.'s H-4MLH200-V4-1S19+ dedicated mirror unit (wavelength 405±5 nm, illuminance 400 mW / cm²). 2 Condition: Working distance from the front end of the mirror unit is 20 mm. Furthermore, as a third method, a multilayer hardened body can also be obtained by placing a layer of commercially available LTHC agent (photothermal conversion agent) on a layer containing at least components (A) to (C) and then hardening it. This provides an effect where a hardened body can be easily obtained. The hardened body obtained using the methods described above can be combined with the attached body to provide it in the form of a structure. Various examples can be cited as manufacturing methods for the structure described above. For example, the first manufacturing method may include the following steps: coating a first temporary fixing composition containing at least components (A) to (C) and not component (D) onto a wafer and performing local curing; coating a second temporary fixing composition containing at least components (A) to (D) onto the locally cured temporary fixing composition; and further placing a transparent substrate onto the coated second temporary fixing composition and performing photocuring. Furthermore, as a second manufacturing method for the structure, the following steps may be included: coating a wafer with a first temporary fixing composition containing at least components (A) to (C) but not component (D), and performing local curing as needed; coating a transparent substrate with a second temporary fixing composition containing at least components (A) to (D), and performing local curing as needed; and bonding the wafer and the transparent substrate by photocuring after bringing their respective sides coated with the temporary fixing composition into close contact. Unlike the aforementioned temporary fixation composition, the same composition used in the temporary fixation composition of this invention can also be used as a raw material for the photothermal conversion (LTHC) layer that absorbs IR laser light and converts it into heat, as described in Japanese Patent No. 4565804. By adding this composition as a component of the photothermal conversion (LTHC) layer, its heat resistance can be improved. In one embodiment, a method for manufacturing a semiconductor wafer is provided, comprising the following steps: coating a temporary fixing composition onto a semiconductor wafer substrate and / or a support member; bonding the semiconductor wafer substrate to the support member; curing the temporary fixing adhesive by irradiating it with light of wavelength 350–700 nm (preferably 365–500 nm, more preferably 385–450 nm) to obtain an adhesive; and irradiating the adhesive with laser light of wavelength not reaching 385 nm (preferably laser light of wavelength 200 nm or higher but not reaching 385 nm) to peel off the semiconductor wafer substrate. The curing and peeling steps of this manufacturing method are both room temperature processes, requiring no heating or cooling components, and typically do not require the use of solvents, offering advantages such as simplicity and short cycle time. Furthermore, the adhesive used for temporary curing can also form a single layer in the aforementioned adhesive. This allows for process simplification or reduction of production time. In a preferred embodiment, by simultaneously including the photoradical polymerization initiator of component (C) and the UV absorber of component (D) in the composition, even a single-layer temporary fixing adhesive can exhibit both a faster curing speed and a faster peeling speed. Furthermore, it can significantly reduce the amount of uncured UV-curable monomers remaining in the cured body during UV curing of the temporary fixing adhesive, improve the heat resistance of the cured body, and reduce volatiles under a nitrogen atmosphere. That is, for example, it can increase the 2% mass reduction temperature of the cured body in Tg / DTA measurements. The high heat resistance of the cured body or the temporary fixing adhesive that reduces volatiles under a nitrogen atmosphere is extremely useful for current semiconductor manufacturing processes. Preferably, the 2% mass reduction temperature of this cured body under a nitrogen atmosphere is 300°C or higher, more preferably 320°C or higher, and even more preferably 326°C or higher. In one embodiment, a method for manufacturing a substrate for an electronic device is provided. This method may include the following steps: mixing monofunctional (meth)acrylate, polyfunctional (meth)acrylate, and a photoradical polymerization initiator to prepare a composition with a viscosity in the range of 500–10000 mPa·s at 23°C; coating the prepared composition onto a silicon wafer using a spin coating method to achieve a flatness with a height difference of only 40 μm or less on the surface of the coated composition; and attaching a support to the silicon wafer in a manner that separates the coated composition from the surface. In this specification, the flatness of the composition surface is measured under the conditions described in the following examples, after coating and curing using a spin coater. [Examples] The present invention will be further described in detail below based on embodiments and comparative examples, but the present invention is not limited thereto. Unless otherwise specified, experiments were conducted at 23°C and 50% humidity. Curable resin compositions (hereinafter sometimes referred to as liquid resin compositions) with the compositions shown in the table below (in parts by mass) were prepared and evaluated. The following compounds were selected as components. [Table 1] [Table 2] (Composition) (A) The following components are used. The surface tension values ​​were measured at 23°C using "OCA20" manufactured by Eiko Seiki Co., Ltd., by the ds / de method. Furthermore, the overall surface tension of the composition was also measured in the same manner. LA: Lauryl acrylate ("LA" manufactured by Osaka Organic Chemical Industry Co., Ltd., surface tension 29.3 mN / m) NOAA: n-Octyl acrylate ("NOAA" manufactured by Osaka Organic Chemical Industry Co., Ltd., surface tension 27.5 mN / m) INAA: Isononyl acrylate ("INAA" manufactured by Osaka Organic Chemical Industry Co., Ltd., surface tension 27.5 mN / m) ISTA: Isostearyl acrylate ("ISTA" manufactured by Osaka Organic Chemical Industry Co., Ltd., surface tension 26.3 mN / m) ACMO: Acrylate morpholine ("ACMO" manufactured by KJ Chemicals Co., Ltd., surface tension 44.6 mN / m) (B) The following components are used. The viscosity value or solid state refers to the viscosity at 23°C. HX-620: Caprolactone-modified neopentyl glycol diacrylate (Kayarad HX-620 manufactured by Nippon Kayaku Co., Ltd., m+n≒4, (average) molecular weight 768, viscosity 290 mPa·s) HX-220: Caprolactone-modified neopentyl glycol diacrylate (Kayarad HX-220 manufactured by Nippon Kayaku Co., Ltd., m+n≒2, (average) molecular weight 541, viscosity 120 mPa·s) A-BPEF-2: 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorenyl diacrylate (NK ESTER A-BPEF-2 manufactured by Shin-Nakamura Chemical Industry Co., Ltd., molecular weight 546, exceeding the testing limit and thus exhibiting high viscosity, with a judged viscosity exceeding 1000 mPa·s) RA-341: Polyfunctional methacrylate polymer (ART CURE manufactured by Negami Kogyo Co., Ltd.) RA-341, the dry polymer has a weight average molecular weight of approximately 70,000, exceeding the testing limit and thus exhibiting high viscosity (viscosity exceeding 1000 mPa·s). A-BPE-2: Ethoxybisphenol A diacrylate (NK ESTER A-BPE-2 manufactured by Shin-Nakamura Chemical Industry Co., Ltd., in the following structural formula R=-CH 2CH 2O-, m=n=1, molecular weight 422, solid at 23℃) [Chemistry 1] RC100C: An acrylate polymer with acrylamide groups at both ends (Kaneka XMAP RC100C manufactured by Kaneka Corporation has the following structural formula, with a molecular weight (weight average) of 24,000, exceeding the testing limit and thus exhibiting high viscosity, with a judged viscosity exceeding 1000 mPa·s). [Chemistry 2] The following components were used as comparative examples: Tetrax 6T: Polyisobutylene (TETRAX Grade 6T manufactured by ENEOS, with a viscosity-average molecular weight of 60,000) A-DCP: Tricyclodecanedimethyl diacrylate (NK ESTER A-DCP manufactured by Shin-Nakamura Chemical Industry Co., Ltd., with a molecular weight of 304 and a viscosity of 160 mPa·s) DCP: Tricyclodecanedimethyl diacrylate (NK ESTER DCP manufactured by Shin-Nakamura Chemical Industry Co., Ltd., with a molecular weight of 332 and a viscosity of 130 mPa·s) (C) The following ingredient is used: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (BASF's "Irgacure 819") (D) The following ingredients are used: 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-bis-butoxyphenyl)-1,3,5-triazine (BASF's "Tinuvin 460"), hydroxyphenyl triazine-based UV absorber (BASF's "Tinuvin 479"), and 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole (Otsuka Chemicals' "RUVA-93"). (Liquid Sample Preparation) A homogeneous mixture was prepared by heating and mixing the materials at 80°C. The viscosities of each component and the overall composition were determined using an Anton-Paar MCR302 rotary rheometer with a cone plate CP50-2, at 23°C and a shear rate of 1 s. -1 The viscosity was measured in the form of a time value. Furthermore, when measuring the viscosity of the polyfunctional (meth)acrylate of component (B) and its comparative example, under the above-mentioned measurement conditions, the rotational rheometer could not measure the viscosity sufficiently due to its high viscosity, and it was clearly determined to be a viscosity exceeding 1000 mPa·s (estimated to be a high viscosity exceeding 100000 mPa·s). (Determination of 2% mass reduction temperature) The liquid resin composition homogenized by the above heating and mixing was sandwiched into a PET film and extruded and stretched until the thickness reached 70 μm, at a cumulative light intensity of 5000 mJ / cm. 2 Hardened samples were prepared under the following conditions. During hardening, a UV-LED (center wavelength 405 nm, illuminance 100 mW / cm²) was used. 2(MAUVBA-0.4×0.6×0.2‐0010 wafer UV irradiator manufactured by Aitec Syste). A 10 mg sample of the hardened material was heated from room temperature to 600 °C using a NETZSCH Japan STA-2500 differential thermal mass analyzer under a nitrogen atmosphere at a carrier gas flow rate of 70 ml / min. The hardened material was then weighed. The mass reduction rate (2% mass reduction temperature) under nitrogen atmosphere was calculated. (Evaluation of Vacuum Heat Resistance) A 4-inch sample was prepared by laminating a 4-inch silicon wafer (10 cm in diameter × 525 μm in thickness) and a 4-inch glass wafer (10 cm in diameter × 0.7 mm in thickness) using a liquid resin composition. During lamination, the thickness of the resin composition was adjusted by adding 0.1% by mass of glass beads (trade name SPL-70, average particle size 70 μm) manufactured by Unitika (with an average particle size of 70 μm) to a temporary fixative and mixing them. After lamination, the cumulative luminous flux of the LED was 5000 mJ / cm². 2 (Center wavelength 405 nm, illuminance 100 mW / cm²) 2 Hardening was performed under the following conditions to prepare the bonded sample. During hardening, a UV-LED (center wavelength 405 nm, illuminance 100 mW / cm²) was used. 2 The wafer UV irradiator (MUVBA-0.4×0.6×0.2‐0010) manufactured by Aitec Systems was used to evaluate the vacuum heat resistance of the obtained bonded samples. Furthermore, the vacuum heat resistance of the obtained bonded samples was evaluated as follows. Each bonded sample was placed in a vacuum heating chamber and heated at 300°C and 20 Pa for 1 hour. The circumferential ends of the silicon wafer were then visually inspected and evaluated according to the following criteria: Excellent: No peeling at the end. Good: The length of the peeled portion at the end is less than 5 mm from the edge. Acceptable: The length of the peeled portion at the end is more than 5 mm from the edge but less than 10 mm. Unacceptable: The length of the peeled portion at the end is more than 10 mm from the edge. (Evaluation of Laser Peelability) For the 4-inch bonded specimens prepared as described above, a UV laser was used to irradiate a 210 mm square area with the specimen fixed at the center, scanning the entire surface of the specimen from the glass support side. The UV laser irradiation conditions are shown below. A KEYENCE MD-U1020C UV laser was used. Irradiation was performed at an output of 2.5 W, a frequency of 40 kHz, a beam diameter of 72 μm, a scanning interval of 150 μm, and a scanning speed of 6 m / sec. Peelability after irradiation was evaluated using the following definitions: "Excellent" refers to a specimen with no adhesion, in which the glass support can be easily peeled off from the temporary fixative by hand. "Good" refers to a specimen with residual adhesion, in which the glass support can be peeled off from the temporary fixative by hand. "Unacceptable" refers to a specimen in which the glass support cannot be peeled off from the temporary fixative by hand. (Evaluation of edge bead height) Using a spin coater (Mikasa MS-A300), 6.5–7.5 g of the prepared resin composition was coated onto an 8-inch Si wafer. After low-speed rotation (50 rpm × 15 sec), high-speed rotation was performed under the following conditions to ensure uniform liquid distribution. The upper surface was moved into the glass chamber, and the chamber was replaced with a nitrogen atmosphere. The cumulative luminous flux of the LED was 8100 mJ / cm². 2 (Center wavelength 405 nm, illuminance 45 mW / cm²) 2 Hardening is performed under the following conditions. The difference between the thickest part of the edge and the part on the inner side more than 2 cm from the edge is taken as the height of the edge bead. High-speed rotation conditions: Rotation time: 15 seconds; Rotation speed: N rpm (using the viscosity value, the rotation speed is the condition that the thickness is 74-76 μm when the coating time is 15 seconds in the following formula); Coating amount: 6.5-7.5 g; Calculation formula: h=h0 / {1+t×(4ω 2 h0 2 / 3ν)} 1 / 2 h: film thickness [mm], h0: initial film thickness [mm], ω: rotational speed [rad / sec], t: time [sec], ν: kinetic viscosity [mm] 2 Rotational speed ω = πN / 30 ω: Rotational speed [rad / sec], rotational speed [rpm] Kinetic viscosity ν = μ / ρ ν: Kinetic viscosity [m 2[ / sec], μ: viscosity [Pa·s], ρ: density [kg / m³] 3 Initial film thickness h0 = {w / (s×ρ)}×10 h0: Initial film thickness [mm], w: Coating amount [g], s: Wafer area [cm²] 2 ], ρ: density [g / cm³] 3 ] Based on the above results, the compositions of the embodiments of the present invention all suppress the edge bead height to below 40 μm, and exhibit good laser peelability and heat resistance. On the other hand, Comparative Examples 1 and 2, which do not contain component (A), have higher edge beads, making it impossible to prevent air bubble ingress. Comparative Examples 3 and 5, which do not meet the surface tension condition of component (A), also have higher edge beads. Comparative Example 4, which does not contain component (B), has poor laser peelability and is impractical.

Claims

1. A composition for temporary fixation, characterized in that it contains the following (A) to (C), and has a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 500 to 10000 mPa·s at atmospheric pressure; (A) a monofunctional (meth)acrylate having a surface tension at 23°C measured by the ds / de method based on the pendant drop method in the range of 20 to 30 mN / m; (B) a polyfunctional (meth)acrylate having a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 1000 mPa·s or more at atmospheric pressure, or being a solid at 23°C, or having a molecular weight of 500 or more and a viscosity at 23°C and a shear rate of 1 s⁻¹ measured by a rotational rheometer in the range of 100 mPa·s or more but less than 1000 mPa·s at atmospheric pressure; (C) a photoradical polymerization initiator. In the mass ratio of component (A) to component (B), the amount of component (A) is in the range of 5% to 65%.

2. The composition for temporary fixation as claimed in claim 1, wherein the amount of component (A) is in the range of 5% to 60% in the mass ratio of component (A) to component (B).

3. The composition for temporary fixation as claimed in claim 1 or 2, wherein component (A) is an aliphatic monofunctional (meth)acrylate.

4. The composition for temporary fixation as claimed in claim 3, wherein the aliphatic group of component (A) has 6 to 30 carbon atoms.

5. The composition for temporary fixation as claimed in claim 1 or 2, wherein component (B) comprises an oligomer or a polymer.

6. The temporary fixation composition of claim 1 or 2 further comprises the following (D): (D) UV absorber.

7. A hardened body, which is a hardened body of the temporary fixation composition as claimed in claim 1 or 2.

8. The hardened body as requested in item 7, under a nitrogen atmosphere, has a 2% mass reduction temperature of 300°C or higher.

9. A method for manufacturing a substrate for an electronic device, comprising the following steps: mixing a monofunctional (meth)acrylate, a polyfunctional (meth)acrylate, and a photoradical polymerization initiator to prepare a composition with a viscosity in the range of 500 to 10000 mPa·s at 23°C, wherein the amount of the monofunctional (meth)acrylate in the composition is in the range of 5% to 65% based on the mass ratio of the monofunctional (meth)acrylate to the polyfunctional (meth)acrylate; coating the prepared composition onto a silicon wafer by spin coating to achieve a flatness with a height difference of only 40 μm or less on the surface of the coated composition; and attaching a support to the silicon wafer in a manner that separates the coated composition from the surface.

10. A temporary fixation adhesive comprising a temporary fixation composition as claimed in any one of claims 1 to 6.

11. An adhesive comprising a temporary fixing adhesive as claimed in claim 10 and a substrate bonded by the temporary fixing adhesive.

12. A method for manufacturing a thin wafer, wherein the temporary fixing adhesive as described in claim 10 is used.