JP7452030B2 - Photocurable resin composition and method for processing base material using the same - Google Patents

Description

The present invention relates to a photocurable resin composition and a method for processing a substrate using the same.

In recent years, various surface treatments have been developed. One example is backgrinding in the manufacturing process of semiconductor devices.

As this type of technology, there is a technology described in Patent Document 1. This document describes that an insulating resin layer (protective film) is formed on one surface of a semiconductor wafer so as to embed a plurality of protruding electrodes, and the surface opposite to the surface on which the insulating resin layer is formed is It is described that the back surface of a semiconductor wafer is ground (back-grinded).

Patent Document 2 discloses an acrylic resin composition containing a predetermined amount of an acrylic oligomer, an acrylic monomer, a thiol compound, and a photoinitiator, and a protective film made of the composition. This document describes that the acrylic resin composition is cured by irradiation from an LED light source.

Patent Document 3 discloses a photocurable resin composition containing a photocurable resin, a photoradical polymerization initiator, and a predetermined amount of liquid resin, and a protective film made of the composition. Epoxy resin is described as the liquid resin.

Japanese Patent Application Publication No. 2009-260219 International Publication No. 2013/073364 Japanese Patent Application Publication No. 2017-160397

However, in the conventional technique described in Patent Document 1, there is room for improvement in terms of both adhesion to semiconductor wafers and removability.
Patent Document 2 has a high curing shrinkage rate and there is room for improvement in adhesion, and there is still room for improvement in terms of both adhesion and releasability to semiconductor wafers.

Furthermore, since the illuminance of an irradiation device using an LED as a light source is low, when an LED irradiation device is used, the photocurable resin composition of Patent Document 3 is not sufficiently cured, and a desired protective film cannot be obtained. Ta.

The present inventors have discovered that, in a predetermined formulation, it is possible to achieve both adhesion and releasability to a substrate, which have a trade-off relationship, and have completed the present invention.
According to the invention,
A liquid photocurable resin composition used as a protective film to protect the surface of the base material opposite to the back surface when polishing the back surface of the base material,
(A) urethane (meth)acrylate resin;
(B) liquid epoxy resin;
(C) a bifunctional or more functional thiol compound;
Provided is a photocurable resin composition comprising:
According to the invention,
A step of placing the photocurable resin composition according to any one of claims 1 to 6 on the surface of the base material;
A flattened film made of the photocurable resin composition is formed on the surface by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays. process and
photocuring the flattening film by irradiating the active energy ray from the light-transmissive film side;
polishing the back surface of the base material opposite to the front surface while the surface of the base material is protected by the protective film;
A method of processing a base material is provided.

According to the present invention, it is possible to provide a photocurable resin composition capable of obtaining a protective film that has both adhesion and removability, and a method for processing a substrate provided with a protective film using the photocurable resin composition.

Embodiments of the present invention will be described below with reference to the drawings. Note that in all the drawings, similar components are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. In addition, "~" represents "more than" to "less than" unless otherwise specified.

The photocurable resin composition of the present embodiment has photocurability and includes a urethane (meth)acrylate resin (A), a liquid epoxy resin (B), and a bifunctional or more functional thiol compound (C). It is a liquid resin composition.

The photocurable resin composition of this embodiment is used as a protective film to protect the surface of the substrate opposite to the back surface during processing of the back surface of the substrate. In other words, the protective film fixes the base material during processing, but can be used as a fixing member that can be peeled off from the base material after processing. Note that such a protective film is a fixing member made of a cured product of a photocurable resin composition.
According to this embodiment, by using a liquid photocurable resin composition, it is possible to form a protective film that protects the surface of the substrate while maintaining the surface structure of the substrate.

In addition, since the photocurable resin composition of this embodiment contains the urethane (meth)acrylate resin (A) and the liquid epoxy resin (B), the curing shrinkage rate is small, and the composition does not follow the substrate surface during curing. Because of its excellent properties, it is possible to obtain a protective film with excellent adhesion to the substrate. In addition to these components (A) and (B), the photocurable resin composition of the present embodiment further contains a bifunctional or more functional thiol compound (C), so that it can be activated by weak activation energy from the LED light source. Furthermore, a protective film with excellent adhesion and removability can be obtained.
Here, the protective film can be suitably used in applications where it is peeled off from the base material using physical peeling means.

[Urethane (meth)acrylate resin (A)]
The urethane (meth)acrylate resin (A) has a urethane skeleton and thus has toughness and flexibility, and is preferable from the viewpoint of low curing shrinkage.

The urethane (meth)acrylate (A) of this embodiment is, for example, a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound such as a polyester type or polyether type with a polyvalent isocyanate compound, and a hydroxyl group Examples include those obtained by reacting (meth)acrylates having the following. Specifically, a bifunctional urethane (meth)acrylate having two acryloyl groups can be used. One or more types of these may be used. Note that the urethane (meth)acrylate of this embodiment may have two or more functional groups.

Examples of polyvalent isocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4 - diisocyanates. Examples of (meth)acrylates having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and polyethylene glycol (meth)acrylate.

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. Thereby, bleed-out of the photo-non-reactive component (B) can be appropriately controlled. Further, the upper limit of the molecular weight of the urethane (meth)acrylate is not particularly limited, but is, for example, 6,000 or less, preferably 3,500 or less, and more preferably 3,000 or less. Thereby, the viscosity of the photocurable resin composition can be appropriately controlled. In this embodiment, the molecular weight can be a number average molecular weight. Note that, as a method for measuring the number average molecular weight, for example, a gel chromatography method can be mentioned.

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 makes it possible to use a urethane (meth)acrylate resin (A) with a low functional group density, thereby achieving an excellent low shrinkage rate. Note that the lower limit of the number of functional groups in the urethane (meth)acrylate resin (A) is not particularly limited, but is, for example, 1 or more, preferably 2 or more. Thereby, curability can be improved.

The lower limit of the content of the urethane (meth)acrylate resin (A) of the present embodiment is not particularly limited, but is, for example, 10% by weight or more, preferably 15% by weight based on the entire photocurable resin composition. % or more, more preferably 20% by weight or more. Thereby, the shrinkage rate of the cured product of the photocurable resin composition of this embodiment can be kept low. Further, the upper limit of the content of the urethane (meth)acrylate resin (A) is, for example, 60% by weight or less, preferably 55% by weight or less, and more preferably 50% by weight or less. Thereby, adhesion can be controlled.

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

The monofunctional epoxy resin of this embodiment is not particularly limited as long as it is liquid at room temperature (25°C) and has one epoxy group in the molecule, but examples include n-butyl glycidyl ether, versa Examples include tic 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. . Butylphenyl glycidyl ether and the like can be used from the viewpoint of improving the viscosity controllability and compatibility of the photocurable resin composition. One or more types of these may be used.

The polyfunctional epoxy resin of this embodiment is an epoxy compound that is liquid at room temperature (25°C) and has two epoxy groups in the molecule (bifunctional epoxy resin) or has three epoxy groups in the molecule. Epoxy compounds (trifunctional epoxy resins) are not particularly limited, but examples include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, Cresol novolac epoxy resins, polybasic acid glycidyl ester type epoxy resins, aminoglycidyl ether type epoxy resins, alicyclic epoxy resins, and the like can be mentioned. Among these, bisphenol A type epoxy resin etc. can be used from the viewpoint of increasing the strength. One or more types of these may be used.

Moreover, the liquid epoxy resin (B) of this embodiment may have a common skeleton with the above-mentioned (meth)acrylate. Examples of such a skeleton include a bisphenol A type skeleton. Thereby, the strength and low shrinkage of the cured product of the photocurable resin composition can be further improved.

The lower limit of the content of the liquid epoxy resin (B) of the present embodiment is, for example, 1% by weight or more, preferably 5% by weight or more, more preferably It is 8% by weight or more. Thereby, the releasability of the cured product of the photocurable resin composition of this embodiment can be further improved. Further, the content of the liquid resin is, for example, 50% by weight or less, preferably 45% by weight or less, and more preferably 40% by weight or less, based on the entire photocurable resin composition. Thereby, the balance between releasability and adhesion in the cured product of the photocurable resin composition of this embodiment can be further improved.

[Difunctional or higher functional thiol compound (C)]
The bifunctional or more functional thiol compound (C) of this embodiment can be used without particular limitation as long as the number of mercapto groups is 2 or more. By including the difunctional or more functional thiol compound (C), even when the illuminance from the LED irradiation device is low, the curing of the photocurable resin composition can be accelerated and the reaction rate can be improved.

Examples of the thiol compound (C) include methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6- Hexanedithiol, bis(mercaptoethyl) sulfide, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-Methylcyclohexane-2,3-dithiol, 1,1-bis(mercaptomethyl)cyclohexane, thiomalic acid bis(2-mercaptoethyl ester), diethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropio) ester), 1,2-dimercaptopropyl methyl ether, 2,3-dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl) ether, ethylene Glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), 1,2-di Mercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl) Benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1 , 3-di(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, 2,4-di(p-mercaptophenyl) ) Bifunctional thiol compounds such as pentane,
1,2,3-propane trithiol, 2,3-dimercapto-1-propanol (2-mercaptoacetate), 2,3-dimercapto-1-propanol (3-mercaptopropionate), 1,2,3- trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, 1,2,3-tris(mercaptomethyl)benzene, 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl) Trifunctional thiol compounds such as benzene,
Examples include tetrafunctional thiol compounds such as pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), and tetrakis(mercaptomethyl)methane. can.

The bifunctional or more thiol compound (C) can contain at least one selected from these, and from the viewpoint of the effects of the present invention, preferably contains a bifunctional or more and tetrafunctional thiol compound, and a tetrafunctional thiol compound (C) It is more preferable that a thiol compound is included. Furthermore, it is preferable that the bifunctional or more functional thiol compound (C) contains a secondary thiol compound among these thiol compounds.

The lower limit of the content of the bifunctional or more functional thiol compound (C) of the present embodiment is, for example, 0.5% by weight or more, preferably 1% by weight or more, based on the entire photocurable resin composition. The content is more preferably 2% by weight or more. Thereby, the reaction rate of the photocurable resin composition of this embodiment with respect to the active energy rays from the LED light source can be increased. Further, the upper limit of the content of the bifunctional or more functional thiol compound (C) is, for example, 20% by weight or less, preferably 15% by weight or less, based on the entire photocurable resin composition, More preferably, it is 10% by weight or less. Thereby, the balance between releasability and adhesion in the cured product of the photocurable resin composition of this embodiment can be improved.

[(meth)acrylate monomer (D)]
The photocurable resin composition of the present embodiment may contain (meth)acrylate monomer (D) as necessary from the viewpoint of adhesion with the base material, low curing shrinkage rate, and handling property (low viscosity). Can be done. In this embodiment, (meth)acrylate represents acrylate, methacrylate, or a mixture thereof, and having a (meth)acrylic group means having one or more acrylic groups, or having one or more methacrylic groups.

The (meth)acrylate monomer (D) is not particularly limited, but includes, for example, monofunctional, bifunctional or trifunctional (meth)acrylates, and trifunctional or higher polyfunctional (meth)acrylates.

In this embodiment, examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. 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 (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 - aliphatic (meth)acrylates such as hydroxybutyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate;
Cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, 3-methyl-3-oxetanylmethyl ( cycloaliphatic (meth)acrylates such as meth)acrylate, 1-adamantyl (meth)acrylate;
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, 2 - aromatic (meth)acrylates such as hydroxy-3-(2-naphthoxy)propyl (meth)acrylate;
Examples include heterocyclic (meth)acrylates such as 2-tetrahydrofurfuryl (meth)acrylate, N-(meth)acryloyloxyethylhexahydrophthalimide, and 2-(meth)acryloyloxyethyl-N-carbazole.

In addition, examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate. 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, 1,3 -Butanediol di(meth)acrylate, 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 Aliphatic (meth)acrylates such as di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate;
Alicyclic (meth)acrylates such as cyclohexanedimethanol (meth)acrylate, tricyclodecane dimethanol (meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, 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, fluorene type di(meth)acrylate ;
Examples include heterocyclic (meth)acrylates such as isocyanuric acid di(meth)acrylate.

Examples of trifunctional or higher polyfunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate. Aliphatic (meth)acrylates such as pentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated glycerin tri(meth)acrylate; heterocyclic (meth)acrylates such as isocyanuric acid tri(meth)acrylate; ) acrylate, etc.

The (meth)acrylate monomer (D) can contain at least one selected from these. Further, from the viewpoint of reactivity, etc., it is preferable to select acrylate, methacrylate, or a mixture thereof. Furthermore, from the viewpoint of low shrinkage, bisphenol A type (meth)acrylate can be used.

Moreover, the (meth)acrylate monomer (D) of this embodiment can contain a monofunctional (meth)acrylate or a bifunctional (meth)acrylate. One or more types of these may be used. Moreover, from the viewpoint of curability, one or more types of bifunctional (meth)acrylates may be used. Furthermore, from the viewpoint of achieving a dense roughness on the surface to which the substrate is adhered, one or more types of monofunctional (meth)acrylates may be used.

The (meth)acrylate monomer (D) includes an alicyclic (meth)acrylate. This further improves adhesion to the base material, low curing shrinkage rate, and handling properties (low viscosity).

[Radical photopolymerization initiator]
The photoradical polymerization initiator of this embodiment can be included.
The photo-radical polymerization initiator is not particularly limited as long as it generates radical species by active energy rays such as ultraviolet rays. By using a photoradical polymerization initiator, an addition reaction occurs due to the unsaturated double bonds of the photocurable functional groups, and the photocurable functional groups are linked together, resulting in polymerization of the photocurable resins. proceed.

Examples of the photoradical polymerization initiator of this embodiment include phenylketones, phosphine oxides, aminobenzoates, and thioxanthones. One or more types of these may be used.

Specific examples of phenylketones include anthraquinone, benzophenone, acetophenone such as 2,2-dimethoxy-1,2-diphenylethan-1-one, and the like.
Specific examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like.
Specific examples of aminobenzoates include 2-benzyl 2-dimethylamino-1-(4-morpholinophenyl)-butanone-1.
Specific examples of thioxanthone include 2,4-diethylthioxatone and the like.

Among these, phenyl ketones, phosphine oxides and aminobenzoates are preferred, and phenyl ketones, especially anthraquinone or benzophenone, are more preferred. Thereby, a cured film can be formed at low cost and at high speed.
When the irradiation source of the active energy ray is an LED light source, the radical photopolymerization initiator can be used without particular limitation, and examples thereof include the above-mentioned radical photopolymerization initiators.

The content of the photoradical polymerization initiator of this embodiment is not particularly limited, but is, for example, 0.01% by weight or more and 5% by weight or less, preferably 0.05% by weight or less, based on the entire photocurable resin composition. The content is from 0.1% to 2% by weight, more preferably from 0.1% to 2% by weight. By setting it within such a range, it is possible to improve photocurability and maintain storage stability.

[Other ingredients]
The photocurable resin composition of this embodiment may contain appropriate amounts of various additives within a range that does not impair the characteristics of the present invention. The additives are not particularly limited, but include, for example, fillers such as inorganic fillers and organic fillers, colorants such as pigments and dyes, antifoaming agents, leveling agents, foaming agents, antioxidants, flame retardants, Examples include ion scavengers and plasticizers. These may be used alone or in combination.

In the cured product of the photocurable resin composition of the present embodiment, the lower limit of the elastic modulus at 25°C is not particularly limited, but is preferably 5 MPa or more, more preferably 5.5 MPa or more, and even more preferably 6 MPa or more. . This makes it possible to suppress resin tearing during peeling and resin residue on the surface. Further, the upper limit of the elastic modulus at 25° C. is not particularly limited, but is preferably, for example, 50 MPa or less, more preferably 45 MPa or less, and even more preferably 40 MPa or less. Thereby, destruction of the surface structure of the base material during peeling can be suppressed.

In the photocurable resin composition of the present embodiment, the lower limit of the viscosity at 25° C. is not particularly limited, but is preferably 1 mPa·s or more, more preferably 10 mPa·s or more, and even more preferably 100 mPa·s or more. . Thereby, excessive flow of the resin can be suppressed, so that the handling properties of the liquid photocurable resin composition can be improved. Further, the upper limit of the viscosity at 25° C. is not particularly limited, but is preferably 2000 mPa·s or less, more preferably 1800 mPa·s or less, and even more preferably 1600 mPa·s or less. Thereby, the planarization film can be formed without affecting the surface structure of the base material such as a semiconductor wafer.

[Method for producing photocurable resin composition]
The method for producing the photocurable resin composition of this embodiment is not particularly limited, but the following mixing method can be used. Specifically, each of the above-mentioned components (components (A), (B), and (C), component (D) added as necessary, radical photopolymerization initiator, and other components) was subjected to ultrasonic waves. Liquid photocurable resin is obtained by dissolving, mixing, and stirring using various mixers such as dispersion method, high-pressure collision dispersion method, high-speed rotation dispersion method, bead mill method, high-speed shear dispersion method, and rotation-revolution dispersion method. A composition can be obtained. For example, the photocurable resin composition of this embodiment can be obtained by stirring a solution containing the above-mentioned components using a stirring blade. It may be dissolved by heating as appropriate.
A method for processing a substrate using the photocurable resin composition of this embodiment will be described.

The base material processing method according to the present embodiment can include, for example, the following arrangement step, flattening step, photocuring step, and processing step. Furthermore, the method for processing the base material can include a peeling step. The placement step includes a step of placing a liquid photocurable resin composition on the surface of a predetermined base material.

The planarization step is performed by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays, thereby forming a layer of the photocurable resin composition on the surface. The method includes a step of forming a planarization film.
The photocuring step includes a step of photocuring the flattening film to form a protective film by irradiating the active energy ray from the light-transmissive film side.
The processing step includes processing a back surface of the base material opposite to the front surface while the surface of the base material is protected by the protective film.
The peeling step includes a step of peeling the protective film from the base material.

By using the photocurable resin composition of this embodiment, a protective film with an excellent balance of adhesion and releasability can be used as a fixing member for a predetermined base material. 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, it is possible to realize a protective film that is optimal for peeling methods using physical means.

The processing method of this embodiment will be specifically explained using an example of back grinding processing. As the base material in this case, a semiconductor wafer with electrodes formed on the surface can be used, but the base material is not limited thereto.

First, a semiconductor wafer having a circuit formed on its surface and a plurality of electrodes protruding from the circuit is prepared. That is, a substrate having a wafer shape, such as such a semiconductor wafer, is used as the base material.

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 the present embodiment, the method for disposing the photocurable resin composition is not limited to the potting method, and for example, a coating method such as spin coating, die coater, spray, etc., or a printing method such as screen printing may be used. good.

Next, using a PET film, the photocurable resin composition is spread over the entire surface of the semiconductor wafer. Then, a flattening film made of a photocurable resin composition is formed over the entire surface of the semiconductor wafer. Since a liquid photocurable resin composition is used, the flattening film can satisfactorily embed a surface having fine irregularities. Alternatively, the photocurable resin composition may be spread out by the weight of the PET film without applying any load from above. Therefore, the planarization film can be formed without affecting the surface structure of the semiconductor wafer.
In this embodiment, the film is not limited to the PET film, and a light-transmitting film that transmits active energy rays such as ultraviolet rays and has a flat surface may be used.

Next, active energy rays are irradiated from the PET film side. Then, the flattening film is photocured by ultraviolet rays transmitted through the PET film to form a protective film. The protective film is a cured product of a photocurable resin composition, and can cover and protect the surface of a semiconductor wafer. Since the photocurable resin composition of the present embodiment contains the difunctional or more functional thiol compound (C), it can be cured and form a protective film even if the active energy ray irradiation source is an LED light source.

Next, the semiconductor wafer is turned over. That is, the back surface of the semiconductor wafer is oriented upward, and the PET film is oriented downward. Then, the PET film is fixed to the stage stand. As a fixing method, for example, a fixing jig such as a wafer ring or a suction method such as a vacuum chuck may be used.

Next, the back surface of the semiconductor wafer is back-grinded. For example, grinding and polishing are performed using a grinding device. Thereby, the back side of the semiconductor wafer can be flattened and thinned. During such a processing step, the protective film protects the semiconductor wafer so as to maintain its surface structure, so that the influence on the surface can be suppressed. Further, by bonding the PET film and the semiconductor wafer, the protective film can fix the position of the semiconductor wafer so that mutual positional shift is suppressed during processing.

After that, the protective film is peeled off from the semiconductor wafer (adherent). For example, peeling can be performed using physical means. Specifically, the protective film is peeled off from the adherend 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, has excellent releasability due to bleed-out of the liquid resin, which is the non-reactive component (B). Therefore, it becomes easy to physically peel off the protective film from the adherend. Note that in this embodiment, a light-transmitting film such as a PET film that has excellent adhesion to the photocurable resin composition is used.

Further, in the PET film, the surface to be bonded to the photocurable resin composition may be treated to facilitate adhesion. That is, an easily adhesive PET film may be used. This can further enhance the adhesion of the photocurable resin composition to the cured product. For example, by using together an easily adhesive PET film having an acrylic layer on the surface and a cured product of a photocurable resin composition containing urethane acrylate, the adhesion between them can be further increased.

Moreover, in this embodiment, from the viewpoint of using the cured product of the photocurable resin composition for physical peeling purposes, it is preferable that the cured product has the following characteristics. For example, by setting the peel strength (for example, 180 degree peel strength against a glass substrate) to 10 N/m or less, the cured product may remain on the surface structure when the base material is peeled off, or the cured product may easily tear when peeled off. can be suppressed.
Furthermore, by setting the curing shrinkage rate of the photocurable resin composition to 7% or less, the composition has excellent conformability to the substrate surface when it is cured, so that the protective film has excellent adhesion to the substrate. can be obtained. Curing shrinkage rate can be measured according to JIS K 6911.
Moreover, by setting the elastic modulus to 5 MPa or more, it is possible to suppress the cured product from remaining on the surface structure or from becoming easily torn during peeling. Furthermore, by setting the elastic modulus to 50 MPa or less, it is possible to suppress destruction of the surface structure during peeling.

In this embodiment, examples of adherends other than the semiconductor wafer include base materials that require surface processing, such as optical materials such as glass, crystal, and sapphire glass, magnetic materials, and ceramic materials. Applications of glass include, for example, optical glasses such as optical lenses, prisms, and arrays, substrates, vibrators, and filters. Applications of sapphire glass include, for example, LED boards, heat sinks for projectors, watch cover glasses, extreme environment windows, mechanical parts such as nozzle guides, inspection jigs, research and experimental equipment parts, and the like. Applications of magnetic materials include, for example, electromagnetic wave shielding materials, electromagnetic wave absorbing materials, and the like. Applications of ceramic materials (especially fine ceramic materials) include materials with electromagnetic functions such as insulation, dielectric, piezoelectric, semiconductor, permanent magnet, and magnetic recording materials, and materials with mechanical functions such as wear-resistant, cutting, and heat-resistant materials. Materials that have a chiropractic function such as artificial bones and artificial tooth root materials, materials that have an optical function such as translucent materials, and materials that have a superconducting function such as superconducting wires and elements.
Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may also be adopted.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples. Unless otherwise specified, "parts" and "%" hereinafter refer to "parts by weight" and "% by weight," respectively.

The manufacturing method of the photocurable resin composition of each Example and each Comparative Example is as follows.
The components listed in Tables 1 to 3 were mixed and stirred using a stirring blade. Thereby, a photocurable resin composition was obtained.

(Urethane (meth)acrylate resin)
・Bifunctional urethane acrylate resin 1: Product number: U200PA, manufactured by Shin Nakamura Chemical Co., Ltd., molecular weight 2700)
・Bifunctional urethane acrylate resin 2: Product number: UA4200, manufactured by Shin Nakamura Chemical Industry Co., Ltd.)

((meth)acrylate monomer)
・Monofunctional aromatic acrylate: Phenoxypolyethylene glycol acrylate (product number: P-200A, manufactured by Kyoeisha Chemical Co., Ltd.)
・Monofunctional alicyclic acrylate: Isobornyl acrylate ・Bifunctional aromatic acrylate: Ethoxylated bisphenol A diacrylate (product number: A-BPE-10, manufactured by Shin Nakamura Chemical Co., Ltd.)
・Trifunctional aliphatic methacrylate: trimethylolpropane trimethacrylate

(liquid epoxy resin)
・Liquid epoxy resin 1: Neopentyl glycol diglycidyl ether ・Liquid epoxy resin 2: 4-tert-butylphenyl glycidyl ether

(thiol compound)
・Tetrafunctional thiol compound: Pentaerythritol tetrakis (3-mercaptobutyrate)

(Photoradical polymerization initiator)
・Photoradical polymerization initiator: 2,2-dimethoxy-2-phenylacetophenone

The following evaluations were performed for each Example and each Comparative Example. The results are shown in Table 1.
(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.) equipped with a cone of 1°34'×R24.

(Peel strength)
A photocurable resin composition was applied to the surface of a glass substrate (slide glass), spread with a PET film, and heated at 1,000 mJ/cm ² using an LED irradiation device (product name: UV PITARI LED, manufactured by Hysol Co., Ltd.). Cures by UV irradiation. The PET film is peeled off, thereby forming a 100 μm photocured film. Thereafter, using Tensilon AG-IS (manufactured by Shimadzu Corporation), the adhesion between the photocured film and the glass substrate was measured as 180 degree peel strength at a peeling rate of 300 mm/min.

(Shrinkage factor)
Consists of a photocured film in which a photocurable resin composition is spread with a PET film and cured by UV irradiation at 1,000 mJ/cm ² using an LED irradiation device (product name: UV PITARI LED, manufactured by Hysol Co., Ltd.) Prepare the sample. The curing shrinkage rate of the sample was calculated in accordance with JIS K6901.

(Surface hardening)
0.1 mL of the photocurable resin composition was potted on a PET film, and UV irradiation was performed at 1,000 mJ/cm ² in the air using an LED irradiation device (product name: UV PITARI LED, manufactured by Hysol Co., Ltd.). Surface hardenability was evaluated based on the following criteria.
○: No liquid substance adheres to the surface even when touched with a finger.
X: When the surface is touched with a finger, a liquid substance is observed.

(Adhesion)
The peel strength measured by the above method was evaluated as adhesion based on the following criteria.
○: Peeling strength is 7 N/m or more ×: Peeling strength is less than 7 N/m

(Physical removability)
The peel strength measured by the above method was evaluated as physical releasability based on the following criteria.
○: Peeling strength is 20N/m or less ×: Peeling strength is greater than 20N/m,

Claims (14)

A liquid photocurable resin composition used as a protective film to protect the surface of the base material opposite to the back surface during polishing of the back surface of the base material, the composition comprising:
(A) urethane (meth)acrylate resin;
(B) liquid epoxy resin;
(C) a difunctional or more functional thiol compound;
A photocurable resin composition containing polyesteramic acid (excluding cases containing polyesteramic acid). The photocurable resin composition according to claim 1, wherein the difunctional or more functional thiol compound (C) includes a secondary thiol compound. The photocurable resin composition according to claim 1 or 2, wherein the difunctional or more functional thiol compound (C) includes a tetrafunctional thiol compound. The photocurable resin composition according to any one of claims 1 to 3, further comprising a (meth)acrylate monomer (D). The photocurable resin composition according to claim 4, wherein the (meth)acrylate monomer (D) includes a monofunctional or difunctional (meth)acrylate. The photocurable resin composition according to claim 4, wherein the (meth)acrylate monomer (D) includes an alicyclic (meth)acrylate. A step of placing a photocurable resin composition containing (A) a urethane (meth)acrylate resin, (B) a liquid epoxy resin, and (C) a difunctional or more functional thiol compound on the surface of a base material. and,
A flattened film made of the photocurable resin composition is formed on the surface by spreading the photocurable resin composition over the entire surface using a light-transmitting film that transmits active energy rays. process and
forming a protective film by photocuring the flattening film by irradiating the active energy ray from the light-transmissive film side;
polishing the back surface of the base material opposite to the front surface while the surface of the base material is protected by the protective film;
Processing methods for base materials, including: In the step of photocuring the flattening film to form the protective film ,
The method for processing a base material according to claim 7, wherein the irradiation source of the active energy ray is an LED light source. After the step of polishing the back surface of the base material,
The method for processing a base material according to claim 7 or 8, comprising a peeling step of physically peeling off the protective film from the base material. The method for processing a substrate according to any one of claims 7 to 9, wherein the difunctional or higher-functional thiol compound (C) includes a secondary thiol compound. The method for processing a substrate according to any one of claims 7 to 10, wherein the difunctional or more functional thiol compound (C) includes a tetrafunctional thiol compound. The method for processing a substrate according to any one of claims 7 to 11, wherein the photocurable resin composition further contains a (meth)acrylate monomer (D). The method for processing a base material according to claim 12, wherein the (meth)acrylate monomer (D) includes a monofunctional or difunctional (meth)acrylate. The method for processing a base material according to claim 12, wherein the (meth)acrylate monomer (D) includes an alicyclic (meth)acrylate.