Method for processing photocurable resin compositions and substrates

Abstract

The present invention provides a photocurable resin composition that can produce a protective film that achieves both processing stability of the substrate and peelability from the substrate (process stability), and a method for processing a substrate equipped with the protective film. [Solution] The photocurable resin composition of the present invention is a liquid photocurable resin composition used as a protective film to protect the surface of the substrate on the opposite side of the back surface when the back surface of the substrate is polished, (A) a urethane (meth)acrylate resin, (B) a liquid epoxy resin, and (C) a (meth)acrylate monomer, A photocurable resin composition in which the sum of the functional group concentration of urethane (meth)acrylate resin (A) calculated by the following formula (1) and the functional group concentration of (meth)acrylate monomer (C) calculated by the following formula (1) is 110 or more and 370 or less. Formula (1): Functional group concentration = [Content in the total photocurable resin composition (%) / weight-average molecular weight (Mw)] × number of reaction sites (number of functional groups) × 1000

Description

Technical Field

[0001] The present invention relates to a photocurable resin composition and a method for processing a substrate.

Background Art

[0002] In recent years, various surface processing treatments have been developed. As an example, back grinding in the manufacturing process of semiconductor devices can be mentioned.

[0003] As a technique of this kind, there is the technique described in Patent Document 1. In this document, with an insulating resin layer (protective film) formed so as to embed a plurality of protruding electrodes formed on one surface of a semiconductor wafer, the back surface of the semiconductor wafer on the side opposite to the surface on which the insulating resin layer is formed is ground (back grinding).

[0004] Patent Document 2 discloses an acrylic resin composition containing an acrylic oligomer, an acrylic monomer, a thiol compound, and a photoinitiator in a predetermined amount, and a protective film made of the composition. In this document, it is described that the acrylic resin composition is cured by irradiation from an LED light source.

[0005] Patent Document 3 discloses a photocurable resin composition containing a photocurable resin, a photo radical polymerization initiator, and a predetermined amount of a liquid resin, and a protective film made of the composition. As the liquid resin, an epoxy resin is described.

[0006] Patent Document 4 discloses a photocurable resin composition containing a urethane (meth) acrylate resin, a liquid epoxy resin, and a polyfunctional thiol compound, and the resin composition can be used for a protective film that protects the surface of the substrate on the side opposite to the back surface of the substrate during grinding of the back surface of the substrate.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] However, the protective films made of resin compositions described in Patent Documents 1 to 4 had room for improvement in terms of the processing stability of the substrate, such as peeling off from the substrate during processing. Furthermore, the protective films also had room for improvement in terms of process stability, such as being difficult to peel off after processing the substrate. [Means for solving the problem]

[0009] The inventors of the present invention have discovered that by using a predetermined resin composition, it is possible to obtain a protective film that can achieve both the processing stability of the substrate and the peelability from the substrate (process stability), which are in a trade-off relationship, and have completed the present invention. In other words, the present invention can be described as follows.

[0010] [1] A liquid photocurable resin composition used as a protective film to protect the surface of the substrate on the opposite side of the back surface when the back surface of the substrate is polished, (A) Urethane (meth)acrylate resin, (B) Liquid epoxy resin and (C)(meth)acrylate monomer and Includes, A photocurable resin composition in which the sum of the functional group concentration of urethane (meth)acrylate resin (A) calculated by the following formula (1) and the functional group concentration of (meth)acrylate monomer (C) calculated by the following formula (1) is 110 or more and 370 or less. Formula (1): Functional group concentration = [(Content relative to the total photocurable resin composition (%) / weight-average molecular weight (Mw)] × number of reaction sites (number of functional groups) × 1000 [2] A liquid photocurable resin composition used as a protective film to protect the surface of the substrate on the opposite side of the back surface when the back surface of the substrate is polished, (A) Urethane (meth)acrylate resin, (B) Liquid epoxy resin and (C)(meth)acrylate monomer and Includes, The curing shrinkage rate measured by method 1 below is 6% or less. A photocurable resin composition having a tensile strength of 0.7 MPa or higher, as measured by method 2 below. (Method 1) The photocurable resin composition was spread out on a PET film, and an LED irradiation device (product name: iGrandage ECS-4011GX / N, manufactured by iGraphics Co., Ltd.) and a light source (product name: M04-L41, M / metal halide lamp, manufactured by iGraphics Co., Ltd.) were used, with a light source wavelength of 200-450 nm and an integrated light intensity of 1,800 mJ / cm². 2 A sample consisting of a photocured film cured by UV irradiation under the specified conditions is prepared, and the curing shrinkage rate of the sample is measured in accordance with JIS K6901. (Method 2) In accordance with JIS K7127, a test specimen (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was subjected to a Shimadzu Autograph S-500 air vise chuck. The specimen was clamped at both ends with a chuck distance of 20 mm, and its breaking strength was measured at a tensile speed of 30 mm / min under an atmosphere of 23°C and 60% RH. [3] The photocurable resin composition according to [1] or [2], wherein the elongation at break measured by method 3 below is 10% or more. (Method 3) In accordance with JIS K7127, a test specimen (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was measured in an atmosphere of 23°C and 60% RH using a Shimadzu Autograph S-500 air vise chuck, with both ends of the specimen clamped with a chuck distance of 20 mm, and the elongation at break was measured at a tensile speed of 30 mm / min based on the following formula. Formula: Breaking elongation = [Chuck travel distance (mm)] ÷ [Initial chuck distance (20 mm)] × 100 [4] The photocurable resin composition according to any one of [1] to [3], wherein the urethane (meth)acrylate resin (A) comprises a bifunctional aliphatic urethane (meth)acrylate resin. [5] The photocurable resin composition according to any one of [1] to [4], wherein the (meth)acrylate monomer (C) comprises a monofunctional or bifunctional (meth)acrylate. [6] The photocurable resin composition according to [5], wherein the (meth)acrylate monomer (C) comprises an alicyclic (meth)acrylate. [7] A photocurable resin composition according to any one of [1] to [6], further comprising a radical polymerization initiator (D). [8] A photocurable resin composition according to any one of [1] to [6], which does not contain a thiol compound with two or more functions. [9] A step of placing a photocurable resin composition according to any of [1] to [8] on the surface of a substrate, A step of forming a planarized film made of the photocurable resin composition on the surface by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays, The process involves irradiating the planarization film with the active energy rays from the light-transmitting film side to photocur the film and form a protective film, With the surface of the substrate protected by the protective film, the step of polishing the back surface of the substrate opposite to the surface, A method for processing a base material, including [the specified element].

[10] In the step of forming the protective film by photocuring the planarization film, The method for processing a substrate according to [9], wherein the irradiation source of the active energy ray is an LED light source.

[11] After the step of polishing the back surface of the substrate, The method for processing a substrate according to [9] or

[10] , including a peeling step of physically peeling the protective film from the substrate.

Effect of the Invention

[0011] According to the present invention, it is possible to provide a photocurable resin composition capable of achieving both processing stability of the substrate and peelability from the substrate (process stability), and a method for processing a substrate provided with the protective film.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description will be omitted as appropriate. Also, for example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified. The notation "(meth)acryl" in this specification represents a concept including both acryl and methacryl. The same applies to similar notations such as "(meth)acrylate".

[0013] <The First Embodiment> The photocurable resin composition of the first embodiment includes (A) a urethane (meth)acrylate resin, (B) a liquid epoxy resin, and (C) a (meth)acrylate monomer.

[0014] The photocurable resin composition of the present embodiment is used for a protective film that protects the surface of the substrate on the side opposite to the back surface during processing of the back surface of the substrate. That is, the protective film can be used as a fixing member that fixes the substrate during processing but can be peeled from the substrate after processing. Such a protective film is a fixing member made of a cured product of the photocurable resin composition.

[0015] In the first embodiment, the sum of the functional group concentration of the urethane (meth)acrylate resin (A) calculated by the following formula (1) and the functional group concentration of the (meth)acrylate monomer (C) calculated by the following formula (1) is 110 or more and 370 or less, preferably 112 or more and 350 or less, more preferably 113 or more and 300 or less, and even more preferably 115 or more and 280 or less. Formula (1): Functional group concentration = [(Content relative to the total photocurable resin composition (%) / weight-average molecular weight (Mw)] × number of reaction sites (number of functional groups) × 1000 The photocurable resin composition of this embodiment exhibits an excellent trade-off balance between low curing shrinkage and high tensile strength, as the total concentration of the functional groups falls within the aforementioned range.

[0016] Because the photocurable resin composition of this embodiment exhibits low curing shrinkage, the protective film made from the photocurable resin composition exerts less stress on the substrate. Therefore, it exhibits excellent adhesion to the substrate and superior processing stability of the substrate. Furthermore, because the cured product obtained from the photocurable resin composition of this embodiment has high tensile strength, the effect of stress when peeling the substrate and protective film after polishing can be suppressed, resulting in excellent peelability.

[0017] [Urethane (meth)acrylate resin (A)] The urethane (meth)acrylate resin (A) is preferred from the viewpoint of low curing shrinkage because it has a urethane skeleton, which provides toughness and flexibility.

[0018] Examples of the urethane (meth)acrylate resin (A) in this embodiment include those obtained by reacting a terminal isocyanate urethane prepolymer, which is obtained by reacting a polyol compound such as a polyester type or polyether type with a polyvalent isocyanate compound, with a (meth)acrylate having a hydroxyl group. Specifically, a bifunctional urethane (meth)acrylate resin having two acryloyl groups can be used, and it is preferable to use a bifunctional aliphatic urethane (meth)acrylate resin or a bifunctional aromatic urethane (meth)acrylate resin, and more preferably a bifunctional aliphatic urethane (meth)acrylate resin. The aliphatic bifunctional urethane (meth)acrylate resin can be obtained by using an aliphatic polyisocyanate as the polyvalent isocyanate compound in the above reaction, and the bifunctional aromatic urethane (meth)acrylate resin can be obtained by using an aromatic polyisocyanate as the polyvalent isocyanate compound in the above reaction. These may be used individually or in combination of two or more types. The urethane (meth)acrylate resin (A) in this embodiment may have two or more functional groups.

[0019] Examples of polyvalent isocyanate compounds include aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and diphenylmethane 4,4-diisocyanate, as well as aliphatic polyisocyanates such as ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate (PDI), and hexamethylene diisocyanate (HDI).

[0020] Examples of (meth)acrylates having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol (meth)acrylate.

[0021] The urethane (meth)acrylate resin (A) may be an oligomer. Examples of oligomers include aliphatic urethane (meth)acrylate oligomers and aromatic urethane (meth)acrylate oligomers, with aliphatic urethane (meth)acrylate oligomers being preferred.

[0022] The lower limit of the molecular weight of the urethane (meth)acrylate resin (A) is, for example, 700 or more, preferably 800 or more, and more preferably 900 or more. This allows for appropriate control of the bleed-out of the photoreactive component (B). The upper limit of the molecular weight of the urethane (meth)acrylate is not particularly limited, but for example, it is 6000 or less, preferably 3500 or less, and more preferably 3000 or less. This allows for appropriate control of the viscosity of the photocurable resin composition. In this embodiment, the molecular weight can be the number-average molecular weight. A method for measuring the number-average molecular weight is, for example, gel chromatography.

[0023] The upper limit of the number of functional groups in the urethane (meth)acrylate resin (A) is, for example, 5 or less, preferably 4 or less, and more preferably 3 or less. This allows the use of a urethane (meth)acrylate resin (A) with a low functional group density, thereby achieving excellent low shrinkage. The lower limit of the number of functional groups in the urethane (meth)acrylate resin (A) is not particularly limited, but for example, it is 1 or more, preferably 2 or more. This improves curability.

[0024] The lower limit of the urethane (meth)acrylate resin (A) content in this embodiment is not particularly limited, but for example, it is 10% by weight or more, preferably 15% by weight or more, and more preferably 20% by weight or more, relative to the total amount of the photocurable resin composition. This makes it possible to keep the shrinkage rate of the cured product of the photocurable resin composition of this embodiment low. The upper limit of the urethane (meth)acrylate resin (A) content is, for example, 60% by weight or less, preferably 55% by weight or less, and more preferably 50% by weight or less. This makes it possible to control the tensile strength.

[0025] In the first embodiment, the urethane (meth)acrylate resin (A) is used such that the sum of the functional group concentration of the urethane (meth)acrylate resin (A) calculated by formula (1) and the functional group concentration of the (meth)acrylate monomer (C) calculated by formula (1) falls within a predetermined range.

[0026] [Liquid epoxy resin (B)] The liquid epoxy resin (B) in this embodiment is liquid at room temperature (25°C) and includes, for example, monofunctional epoxy resins, difunctional epoxy resins, or trifunctional epoxy resins. One or more of these may be used. For example, a monofunctional epoxy resin and a difunctional epoxy resin may be used in combination. Furthermore, by using epoxy resins with different viscosities in combination, the viscosity of the photocurable resin composition can be controlled while maintaining the material properties resulting from the cured product of the urethane (meth)acrylate resin (A). Among these, at least a monofunctional epoxy resin can be used from the viewpoint of good viscosity dilution efficiency and good compatibility with acrylates with similar specific gravities.

[0027] The monofunctional epoxy resin in this embodiment is not particularly limited as long as it is an epoxy compound that is liquid at room temperature (25°C) and has one epoxy group in its molecule. Examples include n-butyl glycidyl ether, versatic acid glycidyl ester, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, butylphenyl glycidyl ether, neopentyl glycol diglycidyl ether, or compounds obtained by hydrogenating the benzene ring of these compounds. From the viewpoint of improving the viscosity controllability and compatibility of the photocurable resin composition, butylphenyl glycidyl ether and the like can be used. One or more of these may be used.

[0028] The polyfunctional epoxy resin in this embodiment is not particularly limited as long as it is liquid at room temperature (25°C) and is an epoxy compound having two epoxy groups in its molecule (bifunctional epoxy resin) or an epoxy compound having three epoxy groups in its molecule (trifunctional epoxy resin). Examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, cresol novolac epoxy resin, polybasic acid glycidyl ester type epoxy resin, aminoglycidyl ether type epoxy resin, alicyclic epoxy resin, etc. Among these, bisphenol A type epoxy resin can be used from the viewpoint of increasing strength. One or more of these may be used.

[0029] Furthermore, the liquid epoxy resin (B) of this embodiment may have a common skeleton with the (meth)acrylate described above. Examples of such skeletons include bisphenol A type. This can further improve the strength and low shrinkage of the cured product of the photocurable resin composition.

[0030] The lower limit of the liquid epoxy resin (B) content in this embodiment is, for example, 10% by weight or more, preferably 15% by weight or more, and more preferably 20% by weight or more, relative to the entire photocurable resin composition. This results in a cured product of the photocurable resin composition of this embodiment exhibiting excellent low curing shrinkage. Furthermore, the liquid resin content is, for example, 70% by weight or less, preferably 65% ​​by weight or less, and more preferably 60% by weight or less, relative to the entire photocurable resin composition. This allows for a further increase in the strength of the cured product of the photocurable resin composition of this embodiment. In other words, by having the liquid epoxy resin (B) content within the above range, the balance between low curing shrinkage and high strength in the cured product of the photocurable resin composition of this embodiment can be further improved.

[0031] [(meth)acrylate monomer (C)] The photocurable resin composition of this embodiment may optionally contain (meth)acrylate monomer (C) from the viewpoint of high tensile strength, low curing shrinkage rate, and handling properties (low viscosity). In this embodiment, (meth)acrylate refers to acrylate, methacrylate, or a mixture thereof, and having (meth)acrylic groups refers to having one or more acrylic groups or one or more methacrylic groups.

[0032] The (meth)acrylate monomer (C) is not particularly limited, but examples include monofunctional, difunctional, or trifunctional (meth)acrylates, and polyfunctional (meth)acrylates with three or more functions.

[0033] In this embodiment, monofunctional (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, butoxyethyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octylheptyl (meth)acrylate, nonyl (meth)acrylate, decyl ( Aliphatic (meth)acrylates such as meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and phenoxypolyethylene glycol (meth)acrylate; Alicyclic (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, 3-methyl-3-oxetanylmethyl (meth)acrylate, and 1-adamantyl (meth)acrylate; Aromatic (meth)acrylates such as phenyl(meth)acrylate, nonylphenyl(meth)acrylate, p-cumylphenyl(meth)acrylate, o-biphenyl(meth)acrylate, 1-naphthyl(meth)acrylate, 2-naphthyl(meth)acrylate, benzyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate, 2-hydroxy-3-(o-phenylphenoxy)propyl(meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl(meth)acrylate, and 2-hydroxy-3-(2-naphthoxy)propyl(meth)acrylate; Examples of heterocyclic (meth)acrylates include 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acryloyloxyethyl hexahydrophthalimide, and 2-(meth)acryloyloxyethyl-N-carbazole.

[0034] Furthermore, examples of difunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and 1,3-butanediol di(meth)acrylate. Aliphatic (meth)acrylates such as phosphate, 2-methyl-1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, and tricyclodecanedimethanol (meth)acrylate; Alicyclic (meth)acrylates such as cyclohexanedimethanol (meth)acrylate, tricyclodecanedimethanol (meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, and hydrogenated bisphenol F di(meth)acrylate; Aromatic (meth)acrylates such as bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, bisphenol AF di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, and fluorene-type di(meth)acrylate; Examples include heterocyclic (meth)acrylates such as isocyanuric acid di(meth)acrylate.

[0035] Examples of polyfunctional (meth)acrylates with three or more functions include aliphatic (meth)acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ethoxylated glycerin tri(meth)acrylate; and heterocyclic (meth)acrylates such as isocyanuric acid tri(meth)acrylate.

[0036] The (meth)acrylate monomer (C) may include at least one selected from these. Furthermore, from the viewpoint of reactivity, it is preferable to select acrylate, methacrylate, or a mixture thereof. Additionally, from the viewpoint of low shrinkage, bisphenol A type (meth)acrylate can be used.

[0037] Furthermore, the (meth)acrylate monomer (C) in this embodiment may include monofunctional (meth)acrylate or difunctional (meth)acrylate. One or more of these may be used. Also, from the viewpoint of curability, one or more difunctional (meth)acrylates may be used. Also, from the viewpoint of achieving a fine surface roughness on the substrate's adhesion surface, one or more monofunctional (meth)acrylates may be used.

[0038] The (meth)acrylate monomer (C) contains an alicyclic (meth)acrylate. This further improves adhesion to the substrate, low curing shrinkage, and handling properties (low viscosity).

[0039] The lower limit of the (meth)acrylate monomer (C) content in this embodiment is not particularly limited, but for example, it is 3% by weight or more, preferably 5% by weight or more, and more preferably 8% by weight or more, relative to the entire photocurable resin composition. This makes it possible to keep the shrinkage rate of the cured product of the photocurable resin composition of this embodiment low and provides excellent handling properties (low viscosity). The upper limit of the urethane (meth)acrylate resin (A) content is, for example, 50% by weight or less, preferably 45% by weight or less, and more preferably 40% by weight or less. This makes it possible to control the tensile strength.

[0040] In the first embodiment, the (meth)acrylate monomer (C) is used such that the sum of the functional group concentration of the urethane (meth)acrylate resin (A) calculated by formula (1) and the functional group concentration of the (meth)acrylate monomer (C) calculated by formula (1) falls within a predetermined range.

[0041] [Photoradical polymerization initiator (D)] The photocurable resin composition of this embodiment may contain a photoradical polymerization initiator (D). The photoradical polymerization initiator (D) is not particularly limited as long as it generates radical species when exposed to active energy rays such as ultraviolet light. By using the photoradical polymerization initiator (D), an addition reaction occurs via the unsaturated double bond of the photocurable functional group, causing the photocurable functional groups to link together, and as a result, polymerization of the photocurable resins proceeds.

[0042] Examples of the photoradical polymerization initiator (D) in this embodiment include phenyl ketones, phosphine oxides, aminobenzoates, thioxanthones, and the like. One or more of these may be used.

[0043] Specific examples of phenyl ketones include anthraquinones, benzophenones, and acetophenones such as 2,2-dimethoxy-1,2-diphenylethane-1-one. Specific examples of phosphine oxides include, for instance, 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Specific examples of aminobenzoates include, for instance, 2-benzyl 2-dimethylamino-1-(4-morpholinophenyl)-butanone-1. Specific examples of thioxanthones include, for instance, 2,4-diethylthioxatone.

[0044] Among these, phenyl ketones, phosphine oxides, and aminobenzoates are preferred, and phenyl ketones, particularly anthraquinone or benzophenone, are preferred. This allows for the formation of a cured film inexpensively and at high speed.

[0045] When the irradiation source of the active energy rays is an LED light source, the photoradical polymerization initiator (D) is not particularly limited and can be used as such, for example, the photoradical polymerization initiator described above.

[0046] The content of the photoradical polymerization initiator (D) in this embodiment is not particularly limited, but for example, it is 0.05% by weight or more and 5% by weight or less, preferably 0.1% by weight or more and 4% by weight or less, and more preferably 0.5% by weight or more and 3% by weight or less, relative to the entire photocurable resin composition. By keeping it within this range, photocurability can be enhanced while maintaining storage stability.

[0047] [Other ingredients] The photocurable resin composition of this embodiment may contain various additives in appropriate amounts, as long as the properties of the present invention are not impaired. These additives are not particularly limited, but examples include fillers such as inorganic or organic fillers, colorants such as pigments or dyes, defoamers, leveling agents, foaming agents, antioxidants, flame retardants, ion scavengers, and plasticizers. One or more of these may be used. The photocurable resin composition of this embodiment preferably does not contain bifunctional or greater thiol compounds.

[0048] [Method for producing a photocurable resin composition] The method for producing the photocurable resin composition of this embodiment is not particularly limited, but the following mixing methods can be used. Specifically, each of the above components can be dissolved, mixed, and stirred using various mixers such as ultrasonic dispersion, high-pressure impact dispersion, high-speed rotation dispersion, bead mill, high-speed shear dispersion, and rotation-orbit dispersion to obtain a liquid photocurable resin composition. For example, the photocurable resin composition of this embodiment can be obtained by stirring a solution containing each of the above components with a stirring blade. The components may also be dissolved by heating as appropriate.

[0049] The photocurable resin composition of this embodiment preferably has a break elongation of 10% or more, more preferably 20% or more, and even more preferably 30% or more, as measured by Method 3 below. The upper limit is not particularly limited, but is 300% or less. By having the elongation at break within the above range, a protective film with superior processing stability and peelability of the substrate can be obtained. (Method 3) In accordance with JIS K7127, a test specimen (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was measured in an atmosphere of 23°C and 60% RH using a Shimadzu Autograph S-500 air vise chuck, with both ends of the specimen clamped with a chuck distance of 20 mm, and the elongation at break was measured at a tensile speed of 30 mm / min based on the following formula. Formula: Breaking elongation = [Chuck travel distance (mm)] ÷ [Initial chuck distance (20 mm)] × 100

[0050] In this embodiment, it is possible to control the elongation at break by appropriately selecting, for example, the type and amount of each component contained in the photocurable resin composition, the method of preparing the photocurable resin composition, and so on.

[0051] <Second Embodiment> The photocurable resin composition of the second embodiment comprises (A) a urethane (meth)acrylate resin, (B) a liquid epoxy resin, and (C) a (meth)acrylate monomer.

[0052] The photocurable resin composition of this embodiment is used as a protective film to protect the surface of the substrate on the opposite side of the back surface during processing of the back surface of the substrate. In other words, the protective film can be used as a fixing member that fixes the substrate during processing but can be peeled off from the substrate after processing. Such a protective film is a fixing member made from the cured product of the photocurable resin composition.

[0053] In the second embodiment, the curing shrinkage rate measured by Method 1 below is 6% or less, preferably 5.5% or less, more preferably 5.3% or less, and even more preferably 5.0% or less. The tensile strength measured by method 2 below is 0.7 MPa or higher, preferably 1.0 MPa or higher, more preferably 1.5 MPa or higher, and even more preferably 1.8 MPa or higher. The range of curing shrinkage and the range of tensile strength can be combined as appropriate. The lower limit of the curing shrinkage is 0.0% or higher, and the upper limit of the tensile strength can be 20 MPa or lower.

[0054] (Method 1) The photocurable resin composition was spread out on a PET film, and an LED irradiation device (product name: iGrandage ECS-4011GX / N, manufactured by iGraphics Co., Ltd.) and a light source (product name: M04-L41, M / metal halide lamp, manufactured by iGraphics Co., Ltd.) were used, with a light source wavelength of 200-450 nm and an integrated light intensity of 1,800 mJ / cm². 2 A sample consisting of a photocured film cured by UV irradiation under the specified conditions is prepared, and the curing shrinkage rate of the sample is measured in accordance with JIS K6901.

[0055] (Method 2) In accordance with JIS K7127, a test specimen (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was subjected to a Shimadzu Autograph S-500 air vise chuck. The specimen was clamped at both ends with a chuck distance of 20 mm, and its breaking strength was measured at a tensile speed of 30 mm / min under an atmosphere of 23°C and 60% RH.

[0056] Because the curing shrinkage rate is within a predetermined range, stress on the substrate is suppressed when forming a resin layer from the photocurable resin composition, which suppresses peeling of the protective film and improves the processing stability of the substrate. Furthermore, because the tensile strength is within a predetermined range, the influence of stress during the separation of the substrate and the resin layer can be suppressed, resulting in excellent peelability.

[0057] There is a trade-off relationship between curing shrinkage and tensile strength, and by combining them at predetermined values, both processing stability and peelability can be resolved. In other words, curing shrinkage and tensile strength can be used as indicators of processing stability and peelability.

[0058] Furthermore, the elongation at break measured by method 3 below is 10% or more, more preferably 20% or more, and even more preferably 30% or more. The upper limit is not particularly limited, but is 300% or less. By having the elongation at break within the above range, a protective film with superior processing stability and peelability of the substrate can be obtained. (Method 3) In accordance with JIS K7127, a test specimen (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was measured in an atmosphere of 23°C and 60% RH using a Shimadzu Autograph S-500 air vise chuck, with both ends of the specimen clamped with a chuck distance of 20 mm, and the elongation at break was measured at a tensile speed of 30 mm / min based on the following formula. Formula: Breaking elongation = [Chuck travel distance (mm)] ÷ [Initial chuck distance (20 mm)] × 100

[0059] In this embodiment, the curing shrinkage rate, tensile strength, and elongation at break can be controlled by appropriately selecting, for example, the type and amount of each component contained in the photocurable resin composition, the method of preparing the photocurable resin composition, and so on.

[0060] The components included in the photocurable resin composition of this embodiment and the method for preparing the composition are the same as those in the first embodiment, so their description will be omitted.

[0061] <Method for processing the base material> A method for processing a substrate using the photocurable resin composition of the first or second embodiment (hereinafter referred to as the photocurable resin composition of this embodiment) will be described below. The substrate processing method according to this embodiment may include, for example, the following placement step, planarization step, photocuring step, and processing step. Furthermore, the substrate processing method may include a peeling step. The placement step includes the step of placing a liquid photocurable resin composition on the surface of a predetermined substrate.

[0062] The planarization step includes a step of forming a planarized film made of the photocurable resin composition on the surface by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays. The photocuring step includes a step of photocuring the planarization film to form a protective film by irradiating it with the active energy ray from the light-transmitting film side. The processing step includes processing the back surface of the substrate opposite to the surface while the surface of the substrate is protected by the protective film. The peeling step includes the step of peeling the protective film from the substrate.

[0063] By using the photocurable resin composition of this embodiment, a protective film with an excellent balance of processing stability and release properties (process stability) from the substrate can be used as a fixing member for a given substrate. Therefore, the processing method of this embodiment can be a method with excellent manufacturing stability. Furthermore, since the strength of the cured product of the photocurable resin composition can be increased, a protective film that is optimal for release methods using physical means can be realized.

[0064] The processing method of this embodiment will be specifically described using a backgrinding process as an example. In this case, a semiconductor wafer with electrodes formed on its surface can be used as the substrate, but is not limited to this.

[0065] First, a semiconductor wafer is prepared, having a circuit formed on its surface and multiple electrodes protruding from the circuit. In other words, a substrate having a wafer shape, such as a semiconductor wafer, is used as the base material.

[0066] Next, a predetermined amount of the photocurable resin composition of this embodiment is potted onto the surface of the semiconductor wafer on which the electrodes are formed. In this embodiment, the method of distributing the photocurable resin composition is not limited to potting, and other coating methods such as spin coating, die coating, or spraying, or printing methods such as screen printing may be used.

[0067] Next, the photocurable resin composition is spread across the entire surface of the semiconductor wafer using a PET film. This forms a planarization film made of the photocurable resin composition over the entire surface of the semiconductor wafer. Because a liquid photocurable resin composition is used, the planarization film can effectively fill in surfaces with fine irregularities. Alternatively, the photocurable resin composition may be spread by the weight of the PET film itself, without applying any load from above. Therefore, a planarization film can be formed without affecting the surface structure of the semiconductor wafer. In this embodiment, the invention is not limited to PET film, but a light-transmitting film that transmits active energy rays such as ultraviolet light and has a flat surface may also be used.

[0068] Next, an active energy ray is irradiated from the PET film side. The planarization film is then photocured by ultraviolet light that has passed through the PET film, forming a protective film. The protective film is a cured product of a photocurable resin composition and can protect the surface of the semiconductor wafer by covering it.

[0069] Next, the semiconductor wafer is flipped over. That is, the back side of the semiconductor wafer faces upwards, and the PET film faces downwards. Then, the PET film is fixed to the stage. For fixing methods, for example, a fixing jig such as a wafer ring or a suction method such as a vacuum chuck may be used.

[0070] Next, the back surface of the semiconductor wafer is back-grinded. For example, grinding and polishing are performed using a grinding device. This flattens and thins the back surface of the semiconductor wafer. During this processing step, the protective film protects the surface structure of the semiconductor wafer, thus suppressing any impact on the surface. Furthermore, the protective film adheres the PET film to the semiconductor wafer, fixing its position so that misalignment between them is suppressed during processing.

[0071] Subsequently, the protective film is peeled off the semiconductor wafer (adhesion substrate). For example, peeling can be performed using physical means. Specifically, the protective film is peeled off the adhesion substrate by pulling the PET film. In this embodiment, the adhesive surface of the protective film, which is a cured product of the photocurable resin composition, exhibits excellent peelability due to the bleed-out of the liquid resin, which is the photoreactive component (B). Therefore, it becomes easy to physically peel the protective film off the adhesion substrate. In this embodiment, a light-transmitting film such as a PET film with excellent adhesion to the photocurable resin composition is used.

[0072] Furthermore, the PET film may be treated with an easy-adhesion treatment on the surface that adheres to the photocurable resin composition. In other words, an easy-adhesion PET film may be used. This can further enhance the adhesion between the PET film and the cured product of the photocurable resin composition. For example, by using an easy-adhesion PET film having an acrylic layer on its surface in combination with a cured product of a photocurable resin composition containing urethane acrylate, the adhesion between them can be further enhanced.

[0073] Furthermore, in this embodiment, from the viewpoint of using the cured product of the photocurable resin composition for physical peeling applications, it is preferable that it has the following characteristics. For example, it is preferable that the peel strength (e.g., 180-degree peel strength against a glass substrate) is 10 N / m or less. The lower limit is preferably 4 N / m or more. By having the above-mentioned peel strength of the cured product of the photocurable resin composition of this embodiment fall within the above range, it is possible to provide a protective film that can achieve both processing stability of the substrate and peelability from the substrate (process stability).

[0074] In this embodiment, substrates other than the semiconductor wafer include, for example, optical materials such as glass, quartz, and sapphire glass, magnetic materials, and ceramic materials, which require surface processing. Examples of applications for glass include optical lenses, prisms, arrays, substrates, oscillators, and filters. Examples of applications for sapphire glass include LED substrates, heat sinks for projectors, watch cover glass, polar environment windows, mechanical parts such as nozzles and guides, inspection jigs, and research and experimental equipment parts. Examples of applications for magnetic materials include electromagnetic wave shielding and absorption materials. Examples of applications for ceramic materials (especially fine ceramic materials) include materials with electromagnetic functions such as insulation, dielectric, piezoelectric, semiconductor, permanent magnet, and magnetic recording material; materials with mechanical functions such as wear resistance, machinability, and heat resistance; materials with holistic fitting functions such as artificial bones and artificial tooth root materials; materials with optical functions such as light-transmitting materials; and materials with superconducting functions such as superconducting wires and elements. The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted. [Examples]

[0075] The present invention will be described in detail below with reference to examples, but the present invention is not limited in any way to the descriptions of these examples. Unless otherwise specified, "parts" and "%" below refer to "weight %".

[0076] The methods for producing the photocurable resin compositions in each example and comparative example are as follows. The components listed in Table 1 were mixed and stirred with a stirring blade. This yielded a photocurable resin composition.

[0077] (Urethane (meth)acrylate resin (A)) • Bifunctional urethane acrylate resin 1: EBECRYL230 (manufactured by Daicel Ornex, number average molecular weight 5000) • Bifunctional urethane acrylate resin 2: UN-6306 (manufactured by Negami Kogyo Co., Ltd., weight-average molecular weight 1000) • Bifunctional urethane acrylate resin 3: EBECRYL8810 (manufactured by Daicel Ornex, weight-average molecular weight 1200) • Bifunctional urethane acrylate resin 4: Quick Cure 8100 (manufactured by KJ Chemicals, weight-average molecular weight 30,000)

[0078] (Liquid epoxy resin (B)) • Liquid epoxy resin: Neopentyl glycol diglycidyl ether

[0079] ((meth)acrylate monomer (C)) • Monofunctional alicyclic acrylate: isobornyl acrylate • Bifunctional aliphatic acrylate: 1,6-Hexanediol diacrylate (A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0080] (Thiol compounds) • 4-functional thiol compound: Pentaerythritol tetrakis(3-mercaptobutyrate) (Photoradical polymerization initiator) • Photoradical polymerization initiator: 2-hydroxy-2-methyl-1-phenylpropan-1-one (Irgacure 1173)

[0081] (Additives) • Additive 1: Hydroquinone monomethyl ether (MEHQ) • Additive 2: Pyrogallol

[0082] The following physical properties were measured for each example and comparative example. The results are shown in Table 1. [Hardening shrinkage rate] The obtained photocurable resin composition was spread out on a PET film, and irradiated using an LED irradiation device (product name: iGrandage ECS-4011GX / N, manufactured by iGraphics Co., Ltd.) and a light source (product name: M04-L41, M / metal halide lamp, manufactured by iGraphics Co., Ltd.) with a light source wavelength of 200-450 nm and an integrated light intensity of 1,800 mJ / cm². 2 Samples consisting of photocured films were prepared by UV irradiation under the specified conditions. The curing shrinkage rate of the samples was then measured in accordance with JIS K6901.

[0083] [Tensile strength] In accordance with JIS K7127, a test specimen (No. 4 dumbbell) was taken from a photocured film (thickness 150-200 μm) obtained under the same conditions as the curing shrinkage rate measurement described above. The fracture strength was measured at a Shimadzu Autograph S-500 air vise chuck at an atmosphere of 23°C and 60% RH, with both ends of the test specimen clamped with a chuck distance of 20 mm, and the tensile speed measured at 30 mm / min.

[0084] [stretch] In accordance with JIS K7127, a test specimen (No. 4 dumbbell) was taken from a photocured film (thickness 150-200 μm) obtained under the same conditions as the curing shrinkage rate measurement described above. The specimen was then measured in an atmosphere of 23°C and 60% RH using a Shimadzu Autograph S-500 air vise chuck, with both ends of the specimen clamped with a chuck distance of 20 mm, and the elongation at break was measured at a tensile speed of 30 mm / min based on the following formula. Formula: Breaking elongation = [Chuck travel distance (mm)] ÷ [Initial chuck distance (20 mm)] × 100

[0085] [viscosity] The viscosity (mPa·s) of the photocurable resin composition was measured at 25°C using an E-type viscometer RE550R (manufactured by Toki Sangyo Co., Ltd.) with a 1°34′×R24 cone.

[0086] [Peel strength (adhesion)] A photocurable resin composition is applied to the surface of a glass substrate (glass slide), spread with a PET film, and irradiated at 1,800 mJ / cm² using an LED irradiation device (product name: UV PITARI LED, manufactured by Hi-Sol Co., Ltd.). 2 The film is cured by UV irradiation. The PET film is peeled off, thereby forming a photocured film with a thickness of 150-200 μm. Subsequently, the adhesion strength between the photocured film and the glass substrate was measured using a Tensilon AG-IS (manufactured by Shimadzu Corporation) as the 180-degree peel strength at a peeling speed of 300 mm / min.

[0087] [Table 1]

Claims

1. A liquid photocurable resin composition used as a protective film to protect the surface of the substrate on the opposite side from the back surface when the back surface of the substrate is polished, (A) Urethane (meth)acrylate resin, (B) Liquid epoxy resin and (C) (meth)acrylate monomer and Includes, A photocurable resin composition in which the sum of the functional group concentration of the urethane (meth)acrylate resin (A) calculated by the following formula (1) and the functional group concentration of the (meth)acrylate monomer (C) calculated by the following formula (1) is 110 or more and 370 or less. Formula (1): Functional group concentration = [(Content in the total photocurable resin composition (%) / weight-average molecular weight (Mw)] × number of reaction sites (number of functional groups) × 1000

2. A liquid photocurable resin composition used as a protective film to protect the surface of the substrate on the opposite side from the back surface when the back surface of the substrate is polished, (A) Urethane (meth)acrylate resin, (B) Liquid epoxy resin and (C) (meth)acrylate monomer and Includes, The curing shrinkage rate measured by method 1 below is 6% or less. A photocurable resin composition having a tensile strength of 0.7 MPa or higher as measured by method 2 below. (Method 1) The photocurable resin composition was spread out on a PET film, and an LED irradiation device (product name: iGrandage ECS-4011GX / N, manufactured by iGraphics Co., Ltd.) and a light source (product name: M04-L41, M / metal halide lamp, manufactured by iGraphics Co., Ltd.) were used, with a light source wavelength of 200-450 nm and an integrated light intensity of 1,800 mJ / cm². ２ A sample consisting of a photocured film cured by UV irradiation under the specified conditions is prepared, and the curing shrinkage rate of the sample is measured in accordance with JIS K6901. (Method 2) In accordance with JIS K7127, a test piece (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was subjected to a 23°C, 60% RH atmosphere. The fracture strength was measured using a Shimadzu Autograph S-500 air vise chuck, with both ends of the test piece clamped with a chuck distance of 20 mm, at a tensile speed of 30 mm / min.

3. The photocurable resin composition according to claim 1 or 2, wherein the elongation at break measured by method 3 below is 10% or more. (Method 3) In accordance with JIS K7127, a test piece (No. 4 dumbbell) taken from the photocured film (thickness 150-200 μm) obtained under the conditions of Method 1 above was measured in a 23°C, 60% RH atmosphere using a Shimadzu Autograph S-500 air vise chuck, with both ends of the test piece clamped with a chuck distance of 20 mm, and the elongation at break was measured at a tensile speed of 30 mm / min based on the following formula. Formula: Elongation at break = [Distance traveled between chucks (mm)] ÷ [Initial distance between chucks (20 mm)] × 100

4. The photocurable resin composition according to claim 1 or 2, wherein the urethane (meth)acrylate resin (A) comprises a bifunctional aliphatic urethane (meth)acrylate resin.

5. The photocurable resin composition according to claim 1 or 2, wherein the (meth)acrylate monomer (C) comprises a monofunctional or bifunctional (meth)acrylate.

6. The photocurable resin composition according to claim 5, wherein the (meth)acrylate monomer (C) comprises an alicyclic (meth)acrylate.

7. Furthermore, the photocurable resin composition according to claim 1 or 2, comprising a radical polymerization initiator (D).

8. A photocurable resin composition according to claim 1 or 2, which does not contain a thiol compound with two or more functions.

9. A step of placing the photocurable resin composition according to claim 1 or 2 on the surface of a substrate, A step of forming a planarized film made of the photocurable resin composition on the surface by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays, The process involves irradiating the planarization film with the active energy rays from the light-transmitting film side to photocur the film and form a protective film, With the surface of the substrate protected by the protective film, the step of polishing the back surface of the substrate opposite to the surface, A method for processing a base material, including [the specified element].

10. In the step of forming the protective film by photocuring the planarized film, The method for processing a substrate according to claim 9, wherein the irradiation source of the active energy rays is an LED light source.

11. After the step of polishing the back surface of the substrate, A method for processing a substrate according to claim 9, comprising a peeling step of physically peeling the protective film from the substrate.

Images