Method of manufacturing electronic device

Abstract

To provide a method of manufacturing an electronic device which suppresses "adhesive deposit" when an adhesive film is peeled off from a wafer (or a diced chip) after a back grinding process.SOLUTION: The method for manufacturing an electronic device includes at least a step (A) of preparing the structural body 100 including the wafer 30 having the circuit forming surface 30A and the adhesive film 50 bonded to the circuit forming surface side of the wafer, a step (B) of back-grinding the surface of the wafer opposite to the circuit forming surface side, and a step (C) of irradiating the adhesive film with ultraviolet light and then removing the adhesive film from the wafer. Here, the loss tangent tan δ at - 5 °C. of the cured film of the ultraviolet-curable adhesive resin material of the adhesive film is 0.25 to 0.85.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electronic device. [Background technology]

[0002] In the process of manufacturing electronic devices, during the wafer grinding step, an adhesive film is sometimes attached to the circuit-formed surface of the wafer in order to fix the wafer and prevent the wafer from being damaged. Such adhesive films generally include a film having an adhesive resin layer laminated on a base film.

[0003] With the advancement of high-density packaging technology, there is a demand for thinner semiconductor wafers, etc., and there is a demand for wafers to be thinned down to a thickness of, for example, 50 μm or less. One such thin grinding process is a pre-dicing method, in which a groove of a predetermined depth is formed on one side of the wafer before grinding, and then the wafer is divided into individual pieces by grinding.Another is a pre-stealth method, in which a modified region is formed inside the wafer by irradiating a laser before grinding, and then the wafer is divided into individual pieces by grinding.

[0004] Examples of technologies relating to adhesive films suitable for application to such dicing-first methods and stealth-first methods include those described in Patent Document 1 (JP 2014-75560 A) and Patent Document 2 (JP 2016-72546 A).

[0005] Patent Document 1 describes a surface protection sheet having a pressure-sensitive adhesive layer on a substrate, which satisfies the following requirements (a) to (d). (a) The Young's modulus of the substrate is 450 MPa or more. (b) The pressure-sensitive adhesive layer has a storage modulus of 0.10 MPa or more at 25°C. (c) The pressure-sensitive adhesive layer has a storage modulus of 0.20 MPa or less at 50°C. (d) The thickness of the adhesive layer is 30 μm or more. Patent document 1 states that such a surface protection sheet can prevent water (sludge) from penetrating into the protected surface of the workpiece through the gaps formed when the workpiece is split during the back grinding process, thereby preventing contamination of the protected surface of the workpiece.

[0006] Patent Document 2 describes an adhesive tape for protecting the surface of a semiconductor wafer, which comprises a base resin film and a radiation-curable adhesive layer formed on at least one side of the base resin film, the base resin film having at least one rigid layer with a tensile modulus of elasticity of 1 to 10 GPa, and the adhesive layer having a peel force of 0.1 to 3.0 N / 25 mm at a peel angle of 30° after being radiation-cured. Patent Document 2 describes that such adhesive tape for protecting the surface of a semiconductor wafer can suppress kerf shift of individual semiconductor chips during the back grinding process of a semiconductor wafer using the pre-dicing method or pre-stealth method, and can process the semiconductor wafer without damaging or contaminating it. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-75560 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-72546 Summary of the Invention [Problem to be solved by the invention]

[0008] According to the investigations of the present inventors, for example, in the manufacturing process of electronic devices, when peeling an adhesive film from a wafer after the back-grinding process, it has become clear that adhesive residue is likely to remain on the dicing streets (scribe lines) on the wafer side. In particular, in the manufacturing process of electronic devices using a dicing-first method or a stealth method, it has become clear that when peeling an adhesive film from a wafer (diced chips) after the back-grinding process, adhesive residue is likely to remain on the wafer side. Specifically, in the dicing-first method, an adhesive film is attached to one side of a wafer that has grooves on one side, which means that adhesive residue is likely to remain in the grooves and / or in the vicinity of the grooves. In particular, the grooves are usually cut using a blade, which makes it easy for minute chips to form in the grooves, which is thought to be one of the causes of adhesive residue. Even in the previous stealth method, when peeling off the adhesive film from the individualized wafer (chip), adhesive residue is likely to remain at the edge of the chip.

[0009] The present invention has been made in view of the above circumstances. One of the objects of the present invention is to suppress "adhesive residue" when peeling an adhesive film from a wafer (or individual chips) after a back-grinding process in the manufacture of electronic devices. [Means for solving the problem]

[0010] The present inventors have investigated improvements to adhesive films for backgrinding from various viewpoints, and as a result have completed the invention provided below, thereby resolving the above-mentioned problems. The present invention is as follows.

[0011] 1. A step (A) of preparing a structure including a wafer having a circuit formation surface and an adhesive film attached to the circuit formation surface side of the wafer; a step (B) of back-grinding the surface of the wafer opposite to the circuit-formed surface; (C) a step of irradiating the adhesive film with ultraviolet light and then removing the adhesive film from the wafer; A method for manufacturing an electronic device comprising at least The adhesive film comprises a base layer and an ultraviolet-curable adhesive resin layer formed on one surface of the base layer using an ultraviolet-curable adhesive resin material, A method for producing an electronic device, wherein the loss tangent tanδ of a cured film of the ultraviolet-curable adhesive resin material at −5° C. is 0.25 to 0.85, as measured as described in the following [Procedure]. [procedure] (i) A film having a thickness of 0.2 mm is formed using the ultraviolet-curable adhesive resin material, and the film is irradiated with ultraviolet light having a dominant wavelength of 365 nm at an irradiation intensity of 100 W / cm using a high-pressure mercury lamp in an environment of 25°C. 2 The UV dose is 1080mJ / cm 2 The composition is irradiated with UV light to cure it, thereby obtaining a cured film. (ii) The dynamic viscoelasticity of the cured film is measured at a frequency of 1 Hz in a tensile mode at a temperature range of -50 to 200°C. 2. 1. A method for manufacturing an electronic device according to claim 1, The step (A) At least one step (A1) selected from a step (A1-1) of half-cutting the wafer and a step (A1-2) of irradiating the wafer with a laser to form a modified layer on the wafer; After the step (A1), a step (A2) of attaching the adhesive film to the circuit-formed surface side of the wafer; A method for manufacturing an electronic device, comprising: 3. 1. A method for manufacturing an electronic device according to 1. or 2., In the step (C), 200 mJ / cm 2 is applied to the adhesive film. 2 More than 2000mJ / cm 2 The adhesive resin layer is photo-cured by irradiating it with ultraviolet light at a dose below 1000 kJ / cm 2 to reduce the adhesive strength of the adhesive resin layer, and then the adhesive film is removed from the wafer. 4. A method for manufacturing an electronic device according to any one of 1. to 3., The adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule, and a photoinitiator. 5. A method for manufacturing an electronic device according to any one of 1. to 4., The method for manufacturing an electronic device, wherein the adhesive resin layer has a thickness of 5 μm or more and 300 μm or less. 6. A method for manufacturing an electronic device according to any one of 1. to 5., A method for manufacturing an electronic device, wherein the resin constituting the substrate layer contains one or more selected from the group consisting of polyolefin, polyester, polyamide, poly(meth)acrylate, polyvinyl chloride, polyvinylidene chloride, polyimide, polyetherimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene ether. 7. A method for manufacturing an electronic device according to any one of 1. to 6., The storage modulus E' of the cured film of the ultraviolet-curable adhesive resin material at 5°C measured as described in the above [Procedure] is 2.0 × 10 7 ~5.0×10 8 A method for manufacturing an electronic device, which is Pa. [Effects of the Invention]

[0012] The method for manufacturing an electronic device of the present invention makes it possible to suppress adhesive residue when peeling the adhesive film from the wafer (or individualized chips) after the backgrinding process. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram (cross-sectional view) schematically illustrating an example of the structure of an adhesive film. [Figure 2]1A to 1C are diagrams (cross-sectional views) schematically illustrating an example of a method for manufacturing an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, similar components are denoted by similar reference numerals and descriptions thereof will be omitted where appropriate. To avoid complexity, (i) when there are multiple identical components in the same drawing, only one of them is given a symbol, and not all of them, or (ii) particularly in Figure 2 and subsequent figures, components similar to those in Figure 1 are not given a symbol again. All drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0015] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0016] In the description of groups (atomic groups) in this specification, when a notation does not specify whether the group is substituted or unsubstituted, it encompasses both groups having no substituents and groups having a substituent. For example, the term "alkyl group" encompasses not only alkyl groups having no substituents (unsubstituted alkyl groups) but also alkyl groups having a substituent (substituted alkyl groups). In this specification, the term "(meth)acrylic" represents a concept that encompasses both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate." Unless otherwise specified, the term "organic group" as used herein means an atomic group obtained by removing one or more hydrogen atoms from an organic compound. For example, a "monovalent organic group" refers to an atomic group obtained by removing one hydrogen atom from any organic compound. In this specification, the term "electronic device" is used to encompass elements, devices, final products, etc. to which electronic engineering technology is applied, such as semiconductor chips, semiconductor elements, printed wiring boards, electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, and chemical batteries.

[0017] FIG. 1 is a cross-sectional view showing a schematic example of the structure of an adhesive film (adhesive film 50) preferably used in this embodiment. The adhesive film 50 is used to protect the surface of the wafer. As shown in FIG. 1, the adhesive film 50 includes a base layer 10 and an ultraviolet-curable adhesive resin layer 20 (an adhesive resin layer made of an ultraviolet-curable adhesive resin material) provided on one side of the base layer 10.

[0018] The loss tangent tanδ of the cured film of the ultraviolet-curable adhesive resin material constituting the adhesive resin layer 20 at −5° C., measured as described in the following [Procedure], is 0.25 to 0.85. [procedure] (i) A film having a thickness of 0.2 mm is formed using an ultraviolet-curing adhesive resin material, and the film is irradiated with ultraviolet light having a dominant wavelength of 365 nm at an irradiation intensity of 100 W / cm using a high-pressure mercury lamp in an environment of 25°C. 2 The UV dose is 1080mJ / cm 2 The composition is irradiated with UV light to cure it, thereby obtaining a cured film. (ii) The dynamic viscoelasticity of the cured film is measured at a frequency of 1 Hz in a tensile mode at a temperature range of -50 to 200°C.

[0019] In order to prevent polymerization from being inhibited by oxygen, the film formed using the ultraviolet-curable adhesive resin material is adhered to, for example, a release film during the ultraviolet irradiation in the above (i). A 0.2 mm thick ultraviolet-curable adhesive resin material having the same composition as the adhesive resin layer 20 is prepared. The ultraviolet-curable adhesive resin material is sandwiched between the silicone release-treated surfaces of colorless, transparent polyethylene terephthalate films (separators) that have been treated with silicone release agents on both sides. Examples of colorless, transparent polyethylene terephthalate films (separators) that have been treated with silicone release include SP-PET T15 and T18 manufactured by Mitsui Chemicals Tocello, and Purex A31 and A41 manufactured by Toyobo. The obtained sample (a three-layer structure of separator / adhesive resin layer 20 / separator) was irradiated with ultraviolet light of a dominant wavelength of 365 nm using a high-pressure mercury lamp at an irradiation intensity of 100 W / cm in an environment of 25°C. 2 The UV dose is 1080mJ / cm 2 Irradiate with UV light to harden. After UV curing, peel off the separators on both sides to prepare a measurement sample, which should be 10 mm wide and 50 mm long. Using a solid viscoelasticity measuring device, set the chuck distance to 20 mm, and measure the viscoelasticity in the temperature range of -50 to 200°C at a frequency of 1 Hz in tension mode. An example of a solid viscoelasticity measuring device is the RSA3 manufactured by TA Instruments.

[0020] One of the features of the adhesive film 50 is that the ultraviolet-curable adhesive resin material that constitutes the adhesive resin layer 20 satisfies the above-mentioned tan δ requirement. The relationship between tan δ of 0.25 to 0.85 and the suppression of adhesive transfer can be explained as follows: Just to be clear, the following description does not limit the present invention.

[0021] Regarding the viscoelasticity of polymers, it is known that frequency change is very similar to temperature change, and that increasing frequency and decreasing temperature have similar effects (time-temperature conversion law). When peeling off the adhesive film, the cured film of the adhesive resin layer is instantaneously deformed greatly. Therefore, it is thought that the viscoelastic behavior in the higher frequency range (i.e., lower temperature range) corresponds well to the actual peeling behavior. In other words, although peeling of the adhesive film after curing is usually performed at room temperature, the inventors have found that tan δ at a lower temperature of -5°C seems to be closely related to the actual peeling behavior. Although the chemical structure of the cured film is difficult to analyze and many aspects remain unknown, it is presumed that a tan δ of over 0.85 at -5°C indicates that the cured film contains a large proportion of components that do not contribute to crosslinking. Such components are thought to cause adhesive residue, particularly in and / or near the grooves created in the wafer by the pre-dicing method. Furthermore, a tan δ of less than 0.25 at -5°C for the cured film is presumably an indication that the energy generated during peeling is not easily converted into thermal energy. If the energy generated during peeling is not easily converted into thermal energy, excessive stress will be concentrated on the corners of the chip or the grooves of the wafer, causing the cured material to undergo cohesive failure and leaving adhesive residue. In other words, it is believed that when the tan δ of the cured film at −5° C. is 0.25 to 0.85, adhesive residue is less likely to be induced.

[0022] With respect to tan δ at −5° C. of the cured film, the lower limit is preferably 0.28 or more, more preferably 0.29 or more, and the upper limit is preferably 0.80 or less, more preferably 0.78 or less.

[0023] In addition, when the viscoelastic properties of the ultraviolet-curable adhesive resin material constituting the adhesive resin layer 20 in the adhesive film 50 were measured according to the above-mentioned [Procedure], the storage modulus E' at 5°C was 2.0 × 10 7 ~5.0×10 8 It is preferable that the adhesive transfer rate is 100 Pa. By satisfying this requirement, adhesive transfer is suppressed to a higher level. Storage modulus E' at 5°C is 2.0 x 10 7 ~5.0×10 8The relationship between Pa and suppression of adhesive residue can be explained as follows (it should be noted that the following description does not limit the present invention).

[0024] Regarding the viscoelasticity of polymers, it is known that frequency change is very similar to temperature change, and that increasing frequency and decreasing temperature have similar effects (time-temperature conversion law). When the adhesive film is peeled off, the cured film of the adhesive resin layer is instantaneously and largely deformed. Therefore, it is thought that the viscoelastic behavior in the higher frequency range (i.e., lower temperature range) corresponds well to the actual peeling behavior. In other words, although the peeling of the adhesive film after curing is usually performed at room temperature, it is presumed that the storage modulus E' at a lower temperature of 5°C is closely related to the actual peeling behavior. Storage modulus E' at 5°C is 5.0 x 10 8 It is presumed that the storage modulus E' at 5°C is 2.0 × 10 Pa or more means that the toughness of the cured film of the adhesive resin layer is significantly impaired, and adhesive residue is likely to remain. 7 It is presumed that the storage modulus E' of the cured film at 5°C is 2.0 × 10 Pa or less means that the interaction between the cured film of the adhesive resin layer and the adherend is too large, making peeling difficult and leaving adhesive residue. 7 ~5.0×10 8 It is believed that the use of Pa makes it even less likely that adhesive residue will be left behind.

[0025] The storage modulus E' of the cured film at 5°C has a lower limit of preferably 2.5 × 10 7 Pa or more, preferably 2.6×10 7 Pa or more, and the upper limit is preferably 4.0 × 10 8 Pa or less, preferably 3.8×10 8 Pa or less.

[0026] An adhesive film having a loss tangent tanδ at −5° C. and a storage modulus E′ at 5° C. of the cured film that satisfy the above numerical ranges can be produced by using an ultraviolet-curable adhesive resin material that is appropriately blended with the materials described below. For particularly preferred blending examples, see the examples below.

[0027] Each layer constituting the adhesive film 50 will be specifically described below in the section "1. Adhesive Film."

[0028] 1. Adhesive film (base material layer) The base layer 10 is a layer provided for the purpose of improving the properties of the adhesive film 50, such as ease of handling, mechanical properties, and heat resistance. The base layer 10 is not particularly limited as long as it has sufficient mechanical strength to withstand the external force applied when processing the wafer, and examples thereof include a resin film. Examples of resins constituting the base layer 10 include one or more selected from polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide; poly(meth)acrylates ((meth)acrylic resins); polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; polyphenylene ether; polyetheretherketone; and polyphenylene ether. Among these, from the viewpoint of improving mechanical properties and transparency, one or more selected from the group consisting of polypropylene, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, ethylene-vinyl acetate copolymer, and polybutylene terephthalate are preferred, and one or more selected from polyethylene terephthalate and polyethylene naphthalate are more preferred.

[0029] The substrate layer 10 may be a single layer or may be made up of two or more layers. The resin film used to provide the base layer 10 may be in the form of a stretched film or a uniaxially or biaxially stretched film. From the viewpoint of improving the mechanical strength of the base layer 10, a uniaxially or biaxially stretched film is preferred. The base layer 10 is preferably annealed in advance to prevent warpage of the wafer after grinding. The base layer 10 may be subjected to a surface treatment to improve adhesion to other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coating treatment, etc. may be performed.

[0030] From the viewpoint of obtaining good film properties, the thickness of the base layer 10 is preferably 20 μm or more and 250 μm or less, more preferably 30 μm or more and 200 μm or less, and even more preferably 50 μm or more and 150 μm or less.

[0031] (Adhesive resin layer) The adhesive film 50 includes an ultraviolet curable adhesive resin layer 20 . The adhesive resin layer 20 is a layer provided on one surface of the base layer 10, and is a layer that comes into contact with and adheres to the circuit-formed surface when the adhesive film 50 is attached to the circuit-formed surface of the wafer.

[0032] The adhesive resin layer 20 is formed using an appropriate ultraviolet-curable adhesive resin material. Specifically, the adhesive resin layer 20 is formed using an ultraviolet-curable adhesive resin material whose adhesive strength is reduced by ultraviolet light. When the adhesive resin layer 20 is irradiated with ultraviolet light, it hardens (crosslinks, etc.) and the adhesive strength decreases, making it easier to peel the wafer (or chips obtained by dividing the wafer) from the adhesive film 50.

[0033] The ultraviolet-curable adhesive resin material preferably contains a (meth)acrylic resin known in the fields of adhesives and adhesives. Examples of (meth)acrylic resins include homopolymers of (meth)acrylic acid ester compounds and copolymers of (meth)acrylic acid ester compounds and comonomers. Examples of (meth)acrylic acid ester compounds that are raw material monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate. These (meth)acrylic acid ester compounds may be used alone or in combination of two or more. Furthermore, examples of comonomers constituting the (meth)acrylic copolymer include vinyl acetate, (meth)acrylonitrile, styrene, (meth)acrylic acid, itaconic acid, (meth)acrylamide, methylol (meth)acrylamide, maleic anhydride, etc. When using these comonomers, they may be used alone or in combination of two or more.

[0034] The ultraviolet-curable adhesive resin material preferably contains a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule (preferably in the side chain and / or terminal), a photoinitiator, and may further contain a crosslinking agent, etc. The ultraviolet-curable adhesive resin material may further contain a low-molecular-weight compound having two or more polymerizable carbon-carbon double bonds in one molecule (such as a polyfunctional (meth)acrylate compound).

[0035] Specifically, a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule (preferably in a side chain and / or terminal) can be obtained as follows: First, a monomer having an ethylenic double bond and a copolymerizable monomer having a functional group (P) are copolymerized. Next, the functional group (P) contained in this copolymer is reacted with a monomer having a functional group (Q) capable of undergoing an addition reaction, condensation reaction, or the like with the functional group (P) while leaving the double bond in the monomer intact, thereby introducing a polymerizable carbon-carbon double bond into the copolymer molecule.

[0036] As the monomer having an ethylenic double bond, one or more of the following may be used: alkyl acrylate and alkyl methacrylate monomers such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, and ethyl (meth)acrylate; vinyl esters such as vinyl acetate; (meth)acrylonitrile, (meth)acrylamide; and monomers having an ethylenic double bond such as styrene.

[0037] Examples of copolymerizable monomers having a functional group (P) include (meth)acrylic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, N-methylol (meth)acrylamide, (meth)acryloyloxyethyl isocyanate, etc. These may be used alone or in combination of two or more. The ratio of the monomer having an ethylenic double bond to the copolymerizable monomer having a functional group (P) is preferably 70 to 99 mass % of the monomer having an ethylenic double bond and 1 to 30 mass % of the copolymerizable monomer having a functional group (P), and more preferably 80 to 95 mass % of the monomer having an ethylenic double bond and 5 to 20 mass % of the copolymerizable monomer having a functional group (P). Examples of the monomer having the functional group (Q) include the same monomers as the copolymerizable monomer having the functional group (P).

[0038] When introducing a polymerizable carbon-carbon double bond into a copolymer of a monomer having an ethylenic double bond and a copolymerizable monomer having a functional group (P), the combination of functional group (P) and functional group (Q) to be reacted is preferably a combination that readily undergoes an addition reaction, such as a carboxyl group and an epoxy group, a carboxyl group and an aziridinyl group, a hydroxyl group and an isocyanate group, etc. In addition to addition reactions, any reaction that readily introduces a polymerizable carbon-carbon double bond, such as a condensation reaction between a carboxylic acid group and a hydroxyl group, can also be applied. When copolymerizing a monomer having an ethylenic double bond with a copolymerizable monomer having a functional group (P), a polymerization initiator can be used. Examples of the polymerization initiator include a radical polymerization initiator such as a benzoyl peroxide polymerization initiator or t-butylperoxy-2-ethylhexanoate.

[0039] Examples of low-molecular-weight compounds having two or more polymerizable carbon-carbon double bonds in one molecule include polyfunctional (meth)acrylate compounds such as tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane tetraacrylate. When these compounds are used, only one compound may be used, or two or more compounds may be used. The amount of the low-molecular-weight compound having two or more polymerizable carbon-carbon double bonds added is preferably 0.1 to 20 parts by mass, more preferably 5 to 18 parts by mass, per 100 parts by mass of the (meth)acrylic resin. The amount of the low-molecular-weight compound having two or more polymerizable carbon-carbon double bonds in the molecule added is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic resin, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 13 parts by mass or less.

[0040] A photoinitiator is generally a compound that generates chemical species (such as radicals) that polymerize polymerizable carbon-carbon double bonds when irradiated with ultraviolet light. Examples of photoinitiators include benzoin, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, acetophenone diethyl ketal, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one, and the like.

[0041] The photoinitiator may be used alone or in combination of two or more kinds. The amount of the photoinitiator added is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 4 to 10 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin. The amount of the photoinitiator added is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, even more preferably 5 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic resin.

[0042] The ultraviolet-curable adhesive resin material may contain a crosslinking agent. Examples of crosslinking agents include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, and diglycerol polyglycidyl ether; aziridine compounds such as tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide); and isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, and polyisocyanate. The crosslinking agent may be used alone or in combination of two or more kinds.

[0043] When a crosslinking agent is used, the amount thereof is usually preferably within a range in which the number of functional groups in the crosslinking agent does not exceed the number of functional groups in the (meth)acrylic resin, but may be contained in excess as necessary when new functional groups are generated in the crosslinking reaction or when the crosslinking reaction is slow. When a crosslinking agent is used, the content of the crosslinking agent in the ultraviolet-curable adhesive resin material is preferably 0.1 parts by mass or more and 15 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the (meth)acrylic resin, from the viewpoint of improving the balance between the heat resistance and adhesion of the adhesive resin layer 20. Furthermore, when a crosslinking agent is used, the content of the crosslinking agent in the ultraviolet-curable adhesive resin material is, from the viewpoint of improving the balance between the heat resistance and adhesion of the adhesive resin layer 20, preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, even more preferably 0.7 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic resin, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less.

[0044] The adhesive resin layer 20 can be formed, for example, by applying an ultraviolet-curable adhesive resin material onto one surface of the base layer 10. That is, the adhesive resin layer 20 can be provided by applying an ultraviolet-curable adhesive resin material prepared by dissolving or dispersing the above components in an appropriate solvent (typically an organic solvent) onto one surface of the base layer 10. Examples of coating methods that can be used include conventional coating methods such as roll coating, reverse roll coating, gravure roll coating, bar coating, comma coating, and die coating. Drying conditions are not particularly limited, but drying is generally performed at a temperature of 80 to 200°C for 10 seconds to 10 minutes. Drying at 80 to 170°C for 15 seconds to 5 minutes is more preferred. To sufficiently promote the crosslinking reaction between the crosslinking agent and the (meth)acrylic resin, the adhesive coating liquid may be heated at 40 to 80°C for approximately 5 to 300 hours after drying.

[0045] As an alternative to applying an ultraviolet-curable adhesive resin material to one side of the base layer 10, as shown in the examples below, (i) first, an ultraviolet-curable adhesive resin material is applied to the surface of an easily peelable base material (separator) to form an adhesive resin layer 20, and (ii) the formed adhesive resin layer is then bonded to one side of the base layer 10.

[0046] The thickness of the adhesive resin layer 20 is preferably 5 μm or more and 300 μm or less, more preferably 10 μm or more and 100 μm or less, and even more preferably 10 μm or more and 50 μm or less. The thickness of the adhesive resin layer 20 is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and preferably 300 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less. Sufficient adhesiveness can be obtained by making the adhesive resin layer 20 appropriately thick. In addition, the adhesive resin layer 20 is not too thick, so that the handleability of the adhesive film 50 is improved.

[0047] (Other layers) The adhesive film 50 may have other layers as long as the effect of suppressing adhesive residue is not impaired. For example, other layers such as an irregularity-absorbing resin layer, an adhesive layer, or an antistatic layer may be present between each layer. By providing an irregularity-absorbing resin layer, the irregularity absorption ability of the adhesive film 50 can be improved. By providing an adhesive layer, the adhesion between each layer can be improved. Furthermore, by providing an antistatic layer, the antistatic ability of the adhesive film 50 can be improved. Furthermore, from the viewpoint of suppressing deterioration and adhesion of foreign matter before use, the exposed surface of the adhesive resin layer 20 may be protected with an appropriate protective film (easily peelable film) such as a release film.

[0048] (total thickness) The total thickness of the adhesive film 50 is preferably 50 μm or more and 600 μm or less, more preferably 50 μm or more and 400 μm or less, and even more preferably 50 μm or more and 300 μm or less, in terms of the balance between mechanical properties and handling properties.

[0049] (Adhesive strength decreases due to exposure to UV rays) As described above, in the adhesive film 50, the adhesive resin layer 20 is formed using an ultraviolet-curable adhesive resin material whose adhesive strength is reduced by ultraviolet light. The degree to which adhesive strength is reduced by ultraviolet light is preferably quantified as follows.

[0050] The adhesive resin layer 20 of the adhesive film 50 is bonded to a mirror-polished silicon wafer, and after leaving it for 1 hour, a peel test is carried out under the conditions of a peel angle of 180° and a peel speed of 300 mm / min. The peel strength when this is done is defined as F0. The adhesive resin layer 20 of the adhesive film 50 and a mirror-polished silicon wafer are bonded together, and ultraviolet light having a wavelength of 365 nm is applied at 1080 mJ / cm. 2 After irradiation, a peel test was carried out under the conditions of a peel angle of 180° and a peel speed of 300 mm / min, and the peel strength measured was designated as F1. ·F1 / F0 is preferably 0.01 to 0.60, more preferably 0.01 to 0.20, and even more preferably 0.02 to 0.20. Furthermore, F1 / F0 is preferably 0.01 or more, more preferably 0.015 or more, more preferably 0.02 or more, and is preferably 0.60 or less, more preferably 0.30 or less, even more preferably 0.20 or less, even more preferably 0.15 or less, even more preferably 0.12 or less.

[0051] By setting F1 / F0 to an appropriate value, the infiltration of grinding water between the wafer and the tape during the back-grinding step is suppressed, and the adhesive film 50 can be easily peeled off after the back-grinding step.

[0052] Incidentally, the value of F0 itself is, for example, 3 to 20 N / 25 mm, specifically 3 to 16 N / 25 mm. The value of F1 itself is, for example, 10 N / 25 mm or less, specifically 1 N / 25 mm or less, more specifically 0.5 N / 25 mm or less. F1 may be zero, but F1 is usually 0.005 N / 25 mm or more, specifically 0.01 N / 25 mm or more.

[0053] 2. Manufacturing method of electronic device FIG. 2 is a cross-sectional view that schematically shows an example of a method for manufacturing an electronic device using the adhesive film 50. As shown in FIG. The method for manufacturing an electronic device includes, for example, at least the following three steps. (A) A step of preparing a structure 100 including a wafer 30 having a circuit-forming surface 30A and an adhesive film 50 attached to the circuit-forming surface 30A side of the wafer 30. (B) A step of back-grinding the surface of the wafer 30 opposite to the circuit formation surface 30A side. (C) A step of irradiating the adhesive film 50 with ultraviolet light and then removing the adhesive film 50 from the wafer 30.

[0054] In this series of steps, the adhesive film described above in the section "1. Adhesive Film" is used as the adhesive film 50. The method for manufacturing an electronic device according to this embodiment is characterized in that the adhesive film 50 is used as a so-called backgrinding tape when grinding the back surface of the wafer 30. Each step of the method for manufacturing an electronic device will now be described.

[0055] (Process (A)) First, a structure 100 is prepared, which includes a wafer 30 having a circuit-forming surface 30A and an adhesive film 50 attached to the circuit-forming surface 30A side of the wafer 30. Such a structure 100 can be produced, for example, by peeling off the release film from the adhesive resin layer 20 of the adhesive film 50 to expose the surface of the adhesive resin layer 20, and then attaching the circuit formation surface 30A of the wafer 30 onto the adhesive resin layer 20.

[0056] Here, the conditions for attaching the circuit-forming surface 30A of the wafer 30 to the adhesive film 50 are not particularly limited, but may be, for example, a temperature of 20 to 80°C, a pressure of 0.05 to 0.5 MPa, and an attachment speed of 0.5 to 20 mm / sec.

[0057] It is preferable that step (A) further includes at least one step (A1) selected from step (A1-1) of half-cutting wafer 30 and step (A1-2) of irradiating wafer 30 with a laser to form a modified layer on wafer 30, and step (A2) of attaching an adhesive film 50 for backgrinding to the circuit formation surface 30A side of wafer 30 after step (A1). As described above, the adhesive film 50 according to this embodiment can be suitably used in the manufacturing process of electronic devices using a dicing-first method, a stealth-first method, etc. Therefore, a manufacturing method that performs step (A1-1) of the dicing-first method or step (A1-2) of the stealth-first method is preferred.

[0058] In step (A2), the adhesive film 50 can be heated and attached to the circuit-forming surface 30A of the wafer 30. This allows the adhesive resin layer 20 and the wafer 30 to maintain a good adhesive state for a long period of time. The heating temperature is not particularly limited, but is, for example, 60 to 80°C.

[0059] The operation of attaching the adhesive film 50 to the wafer 30 may be performed manually, but generally, it can be performed by a device called an automatic attachment machine equipped with a roll of adhesive film.

[0060] The wafer 30 to be attached to the adhesive film 50 is not particularly limited, but is preferably a wafer 30 having a circuit-forming surface 30A. Examples include a semiconductor wafer, an epoxy molded wafer, and an epoxy molded panel, with semiconductor wafers and epoxy molded wafers being preferred. Examples of semiconductor wafers include silicon wafers, sapphire wafers, germanium wafers, germanium-arsenic wafers, gallium-phosphorus wafers, gallium-arsenic-aluminum wafers, gallium-arsenic wafers, and lithium tantalate wafers, and are preferably used with silicon wafers. Examples of epoxy mold wafers include wafers produced by the eWLB (Embedded Wafer Level Ball Grid Array) process, which is one of the methods for producing fan-out WLPs. The semiconductor wafer and epoxy mold wafer having a circuit-forming surface are not particularly limited, and examples thereof include those having circuits such as wiring, capacitors, diodes, or transistors formed on the surface. The circuit-forming surface may also be plasma-treated.

[0061] The circuit formation surface 30A of the wafer 30 may be an uneven surface due to the presence of bump electrodes or the like. For example, when mounting an electronic device on a mounting surface, the bump electrode is bonded to an electrode formed on the mounting surface to form an electrical connection between the electronic device and the mounting surface (the mounting surface of a printed circuit board or the like). Examples of bump electrodes include ball bumps, printed bumps, stud bumps, plated bumps, and pillar bumps. That is, bump electrodes are usually convex electrodes. These bump electrodes may be used alone or in combination of two or more types. The height and diameter of the bump electrodes are not particularly limited, but are preferably 10 to 400 μm, more preferably 50 to 300 μm, respectively. The bump pitch is also not particularly limited, but is preferably 20 to 600 μm, more preferably 100 to 500 μm. The metal species constituting the bump electrode is not particularly limited, and examples thereof include solder, silver, gold, copper, tin, lead, bismuth, and alloys thereof, but the adhesive film 50 is suitably used when the bump electrode is a solder bump. These metal species may be used alone or in combination of two or more.

[0062] (Process (B)) Next, the surface of the wafer 30 opposite to the circuit formation surface 30A (also referred to as the back surface) is back-ground. "Back grinding" means thinning the wafer 30 to a predetermined thickness without damaging it. For example, the structure 100 is fixed to a chuck table or the like of a grinding machine, and the back surface (surface on which no circuit is formed) of the wafer 30 is ground.

[0063] In this backside grinding operation, the wafer 30 is ground until its thickness is equal to or less than a desired thickness. The thickness of the wafer 30 before grinding is determined appropriately depending on the diameter, type, etc. of the wafer 30, and the thickness of the wafer 30 after grinding is determined appropriately depending on the size of the chip to be obtained, type of circuit, etc. Furthermore, if the wafer 30 is half-cut or a modified layer is formed by laser irradiation, the wafer 30 is divided into individual chips 31 in step (B) as shown in FIG.

[0064] The backside grinding method is not particularly limited, and any known grinding method can be used. Grinding can be performed while cooling the wafer 30 and the grindstone by spraying water on them. If necessary, a dry polishing step, which is a grinding method that does not use grinding water, can be performed at the end of the grinding step. After back grinding is completed, chemical etching is performed as needed. Chemical etching is performed by immersing the wafer 30 with the adhesive film 50 attached in an etching solution selected from the group consisting of an acidic aqueous solution consisting of a single or mixed solution of hydrofluoric acid, nitric acid, sulfuric acid, acetic acid, etc., and an alkaline aqueous solution such as a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution. Etching is performed for the purposes of removing distortion generated on the back surface of the wafer 30, further thinning the wafer 30, removing oxide films, etc., and pretreatment for forming electrodes on the back surface. The etching solution is appropriately selected depending on the purpose.

[0065] (Process (C)) Next, the adhesive film 50 is irradiated with ultraviolet light, and then the adhesive film 50 is removed from the wafer 30. In step (C), the adhesive film 50 is irradiated with ultraviolet light of, for example, 200 mJ / cm 2 2 More than 2000mJ / cm 2 By irradiating the adhesive resin layer 20 with ultraviolet light at the dose below, the adhesive resin layer 20 is cured with ultraviolet light to reduce the adhesive strength of the adhesive resin layer 20, and then the adhesive film 50 is removed from the wafer 30. The ultraviolet irradiation can be carried out, for example, by using ultraviolet rays with a dominant wavelength of 365 nm using a high-pressure mercury lamp. The irradiation intensity of the ultraviolet light is, for example, 50 mW / cm 2 More than 500mW / cm 2 The following is the result.

[0066] Before removing the adhesive film from the wafer 30, the wafer 30 may be mounted on a dicing tape or a dicing tape with a die attach film together with a ring frame. The operation of removing the adhesive film 50 from the wafer 30 may be performed manually, but is generally performed by a device called an automatic peeler. The surface of the wafer 30 after peeling off the adhesive film 50 may be cleaned as needed. Examples of cleaning methods include wet cleaning such as water cleaning or solvent cleaning, and dry cleaning such as plasma cleaning. In the case of wet cleaning, ultrasonic cleaning may be used in combination. The cleaning method can be selected appropriately depending on the contamination state of the surface of the wafer 30.

[0067] (Other processes) After steps (A) to (C) are performed, a step of mounting the obtained chip 31 on a circuit board may be further performed. These steps can be performed based on known information.

[0068] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0069] The embodiments of the present invention will be described in detail based on examples and comparative examples. However, it should be noted that the present invention is not limited to the examples. In the examples, exponential notation may be indicated by the symbol "E." For example, 1.3E+06 is expressed as 1.3 x 10 6 means.

[0070] <Preparing raw materials> The following raw materials were prepared:

[0071] (base material layer) Base layer 1: Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E7180, thickness: 50 μm, one-sided corona treatment)

[0072] Base layer 2: A laminated film (total thickness: 110 μm) consisting of a low-density polyethylene film / polyethylene terephthalate film / low-density polyethylene film, produced as follows: A polyethylene terephthalate film (manufactured by Toray Industries, product name: Lumirror S10, thickness: 50 μm) was attached to both sides of a low-density polyethylene film (density: 0.925 kg / m 3 One side of the obtained laminated film was subjected to corona treatment.

[0073] Base layer 3: A laminated film (total thickness: 145 μm) made of polyethylene terephthalate film / ethylene-vinyl acetate copolymer film / acrylic film, produced as follows: Polyethylene terephthalate film (Toyobo Co., Ltd., product name: E7180, thickness: 50 μm) and ethylene-vinyl acetate copolymer (Mitsui-Dow Polychemicals Co., Ltd., MFR: 2.5 g / 10 min) film (thickness: 70 μm) were laminated by applying corona discharge treatment to the bonding surface of the ethylene-vinyl acetate copolymer film. In addition, the opposite side of the ethylene-vinyl acetate copolymer film to the PET film was also corona discharge treated. Next, the release surface of a release-treated polyethylene terephthalate film (separator) was coated with the acrylic resin coating solution for the base layer shown below to a dry thickness of 20 μm, dried, and then bonded to the above-mentioned polyethylene terephthalate film / ethylene-vinyl acetate copolymer film laminate film via the ethylene-vinyl acetate copolymer film, and aged (40°C for 3 days).The separator was then peeled off. In this manner, the base layer 3 was obtained.

[0074] (Acrylic resin coating liquid for base layer) Using 0.5 parts by weight of 4,4'-azobis-4-cyanovaleric acid (Otsuka Chemical Co., Ltd., product name: ACVA) as a polymerization initiator, 74 parts by weight of butyl acrylate, 14 parts by weight of methyl methacrylate, 9 parts by weight of 2-hydroxyethyl methacrylate, 2 parts by weight of methacrylic acid, 1 part by weight of acrylamide, and 3 parts by weight of an aqueous solution of polyoxyethylene nonylpropenylphenyl ether ammonium sulfate (Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) was emulsion polymerized in deionized water at 70°C for 9 hours. After polymerization was completed, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous acrylic polymer emulsion with a solids concentration of 42.5% by weight. Next, 100 parts by mass of this acrylic polymer aqueous emulsion was adjusted to pH 9 or higher using ammonia water, and 0.75 parts by mass of an aziridine crosslinker (ChemiTite PZ-33, manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.) and 5 parts by mass of diethylene glycol monobutyl ether were added. In this manner, an acrylic resin coating liquid for the substrate layer was obtained.

[0075] ((Meth)acrylic resin solution) (Meth)acrylic resin solution 1: 49 parts by mass of ethyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 21 parts by mass of methyl acrylate, 10 parts by mass of glycidyl methacrylate, and 0.5 parts by mass (solids content) of a benzoyl peroxide polymerization initiator were reacted in a mixed solvent of 65 parts by mass of toluene and 50 parts by mass of ethyl acetate at 80°C for 10 hours. After completion of the reaction, the resulting solution was cooled, and 25 parts by mass of xylene, 5 parts by mass of acrylic acid, and 0.5 parts by mass of tetradecyldimethylbenzylammonium chloride were added to the cooled solution, followed by reaction at 85°C for 32 hours while blowing in air. In this manner, a (meth)acrylic resin solution 1 was obtained.

[0076] (Meth)acrylic resin solution 2: 77 parts by mass of n-butyl acrylate, 16 parts by mass of methyl methacrylate, 16 parts by mass of 2-hydroxyethyl acrylate, and 0.3 parts by mass of t-butylperoxy-2-ethylhexanoate as a polymerization initiator were reacted in a mixed solvent of 20 parts by mass of toluene and 80 parts by mass of ethyl acetate at 85°C for 10 hours. After completion of the reaction, the resulting solution was cooled, and to this were added 30 parts by mass of toluene, 7 parts by mass of methacryloyloxyethyl isocyanate (manufactured by Showa Denko, product name: Karenz MOI), and 0.05 parts by mass of dibutyltin dilaurate, and the reaction was carried out at 85°C for 12 hours while blowing air into it. In this manner, a (meth)acrylic resin solution 2 was obtained.

[0077] (Meth)acrylic resin solution 3: 30 parts by mass of ethyl acrylate, 11 parts by mass of methyl acrylate, 26 parts by mass of 2-ethylhexyl acrylate, 7 parts by mass of 2-hydroxyethyl methacrylate, and 0.8 parts by mass (solids content) of a benzoyl peroxide polymerization initiator were reacted in a mixed solvent of 7 parts by mass of toluene and 50 parts by mass of ethyl acetate at 80° C. for 9 hours. After completion of the reaction, the resulting solution was cooled, and 25 parts by mass of toluene was added to the cooled solution. In this manner, a (meth)acrylic resin solution 3 was obtained.

[0078] (photoinitiator) Omnirad 651 (IGM): 2,2-dimethoxy-2-phenylacetophenone Omnirad 369 (IGM): 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone

[0079] (Multifunctional (meth)acrylate) Aronix M400 (manufactured by Toagosei Co., Ltd.): a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate

[0080] (Crosslinking agent) Isocyanate-based crosslinking agent (Mitsui Chemicals, product name: Olestar P49-75S)

[0081] <Preparation of UV-curable adhesive resin material (coating liquid for forming adhesive resin layer)> The materials listed in the "UV-curable adhesive resin material (coating liquid for forming adhesive resin layer)" column of Table 1 were uniformly mixed to obtain an UV-curable adhesive resin material (coating liquid for forming adhesive resin layer).

[0082] <Viscoelasticity measurement of cured films of UV-curable adhesive resin materials> First, the UV-curable adhesive resin material (coating liquid for forming an adhesive resin layer) listed in Table 1 was applied to a silicone release-treated polyethylene terephthalate film (separator) (Mitsui Chemicals Tohcello SP-PET T18 (thickness 31 μm)). Next, the film was dried at 120°C for 3 minutes to form an adhesive resin layer with a thickness of 30 to 40 μm. Several of the resulting adhesive resin layers were stacked together to obtain a laminate sample with a separator / 0.2 mm thick adhesive resin layer / separator configuration. The resulting laminate sample was heated in an oven at 40°C for 3 days and aged. The obtained laminate sample (separator / adhesive resin layer / separator structure) was irradiated with ultraviolet light having a dominant wavelength of 365 nm using a high-pressure mercury lamp at an irradiation intensity of 100 W / cm in an environment of 25°C. 2 The UV dose is 1080mJ / cm 2 The coating was then irradiated with UV light to cure. Next, the viscoelasticity was measured using a solid viscoelasticity measuring device (TA Instruments, RSA3). Specifically, the cured laminate sample was cut to a width of 10 mm and a length of 50 mm, and the separators on both sides of the cured laminate sample were removed to obtain a measurement sample. The measurement sample was then set in the device so that the distance between the chucks was 20 mm. The dynamic viscoelasticity was then measured at a frequency of 1 Hz in tension mode over a temperature range of -50 to 200°C.

[0083] <Preparation of adhesive film> First, the ultraviolet-curable adhesive resin material (coating liquid for forming an adhesive resin layer) shown in Table 1 was applied to a polyethylene terephthalate film (separator) that had been treated with silicone release agent, and then dried at 120°C for 3 minutes to form an adhesive resin layer with a thickness of 20 μm. The formed adhesive resin layer was attached to a substrate layer to form a laminate. Specifically, when substrate layer 1 or 2 was used as the substrate layer, it was attached to the corona-treated surface. When substrate layer 3 was used as the substrate layer, the separator was peeled off and the layer was attached to the acrylic film layer side. The resulting laminate was heated in an oven at 40°C for 3 days and aged. In this way, an adhesive film for back grinding was obtained.

[0084] <Confirmation of basic physical properties> (1) Adhesion evaluation: Measurement of adhesion before and after UV irradiation (i) Preparation of adherend wafer for adhesion measurement: The mirror surface of a silicon mirror wafer (4-inch single-sided mirror wafer manufactured by SUMCO Corporation) was ozone cleaned using a UV ozone cleaning device (UV-208 manufactured by Technovision Co., Ltd.) (ozone treatment time: 60 seconds). The wafer mirror surface was then wiped with ethanol to prepare the adherend wafer.

[0085] (ii) Measurement of adhesive strength before UV irradiation: In an environment of 23°C and 50% RH, the adhesive film obtained in <Preparation of adhesive film> was cut into a width of 50 mm, the separator was peeled off, and the adhesive film was attached to the mirror surface of the adherend wafer via its adhesive resin layer using a hand roller, and then left to stand for 1 hour. After leaving it, one edge of the adhesive film was clamped using a tensile tester (Shimadzu Corporation, product name: Autograph AGS-X) and the adhesive film was peeled off from the surface of the adherend wafer at a peel angle of 180° and a peel speed of 300 mm / min. The stress at this time was measured and converted to N / 25 mm to determine the adhesive strength. The evaluation was performed with N=2, and the two obtained values ​​were averaged to determine the peel strength F0.

[0086] (iii) Measurement of adhesive strength after UV irradiation: Under an environment of 23°C and 50% RH, the adhesive film for adhesive strength evaluation was cut into a width of 50 mm, the separator was peeled off, and the adhesive film was attached to the mirror surface of the wafer via its adhesive resin layer using a hand roller, and then left to stand for 1 hour. After leaving it, it was irradiated with ultraviolet light of a dominant wavelength of 365 nm using a high-pressure mercury lamp at an irradiation intensity of 100 mW / cm in an environment of 25°C. 2 The adhesive film is exposed to a UV dose of 1080mJ / cm 2 The adhesive film was then irradiated. One end of the adhesive film was then clamped using a tensile tester (Shimadzu Corporation, product name: Autograph AGS-X), and the adhesive film was peeled off from the surface of the adherend wafer at a peel angle of 180° and a peel speed of 300 mm / min. The stress at this time was measured and converted to N / 25 mm to determine the adhesive strength. The evaluation was performed with N=2, and the two obtained values ​​were averaged to determine the peel strength F1. Then, F1 / F0 was calculated from the obtained F1 and F0 values.

[0087] (2) Adhesive residue evaluation In the above (iii), the adherend wafer after UV peeling was visually observed to determine whether or not there was any adhesive residue. If no adhesive residue was observed, it was recorded as "none" in Table 1.

[0088] <Various evaluations of the pre-dicing method> (1) Preparation of evaluation wafer Evaluation wafer 1: Using a dicing saw, the mirror surface of a mirror wafer (KST World Corporation, 8-inch mirror wafer, diameter: 200±0.5 mm, thickness: 725±50 μm, single-sided mirror) was half-cut to obtain evaluation wafer 1. (Blade: ZH05-SD3500-N1-70-DD, chip size: 5 mm × 8 mm, cutting depth: 58 μm, blade rotation speed: 30,000 rpm). When evaluation wafer 1 was observed with an optical microscope, the kerf width was found to be 35 μm.

[0089] Evaluation wafer 2: A first half-cut was performed on the mirror surface of a mirror wafer (KST World Corporation, 8-inch mirror wafer, diameter: 200±0.5 mm, thickness: 725±50 μm, single-sided mirror) using a dicing saw (blade: Z09-SD2000-Y1 58×0.25A×40×45E-L, chip size: 5 mm × 8 mm, cutting depth: 15 μm, blade rotation speed: 30,000 rpm). Observation with an optical microscope revealed a kerf width of 60 μm. Next, a second half-cut was performed (blade: ZH05-SD3500-N1-70-DD, chip size: 5 mm × 8 mm, cutting depth: 58 μm, blade rotation speed: 30,000 rpm) to obtain evaluation wafer 2.

[0090] (2) Implementation of the pre-dicing method and various evaluations Using a tape laminator (DR3000II, manufactured by Nitto Denko Corporation), an adhesive film was attached to the half-cut surface of the above evaluation wafer (evaluation wafer 1 or 2) (23°C, attachment speed: 5 mm / sec, attachment pressure: 0.36 MPa). Next, the wafer was back-ground using a grinder (DISCO, DGP8760) (rough grinding and precision grinding, precision grinding amount: 40 μm, no polishing, thickness after grinding: 38 μm) and divided into individual pieces.

[0091] After that, UV irradiation and peeling of the adhesive film were performed, and the device peelability and adhesive residue after the pre-dicing method were evaluated. Specifically, UV irradiation was performed using a high-pressure mercury lamp at a temperature of 25°C, with ultraviolet light of a dominant wavelength of 365 nm and an irradiation intensity of 100 mW / cm. 2 The adhesive film is exposed to 1080mJ / cm of UV light. 2 was irradiated. The adhesive film was peeled off using the following procedure. First, a separately prepared dicing tape (used as mounting tape) was attached to an 8-inch wafer ring frame and the wafer side of the individualized wafer using a wafer mounter (MSA300, manufactured by Nitto Denko Corporation) via the adhesive surface of the dicing tape. Next, the adhesive film for dicing evaluation was peeled off from the wafer notch using a peeling tape (PET38REL, manufactured by Lasting Systems Co., Ltd.) using a tape peeler (HR3000III, manufactured by Nitto Denko Corporation). The device releasability was then evaluated. In Table 1, the case where the adhesive film for pre-dicing evaluation could be peeled from the wafer in one go was recorded as "OK."

[0092] In addition, adhesive residue on the individual wafers after pre-dicing was observed and evaluated using an optical microscope (Olympus Corporation). In the observation, the presence of thread-like adhesive residue was particularly checked in the areas where grooves had been formed in advance. In Table 1, cases where no adhesive residue was observed were marked "OK," and cases where adhesive residue was observed were marked "Present."

[0093] Various information is summarized in Table 1. The unit of E' is Pa.

[0094] [Table 1]

[0095] As shown in Table 1, when manufacturing electronic devices using the pre-dicing method, the occurrence of adhesive residue was suppressed by using an adhesive film having an adhesive resin layer made of an ultraviolet-curable adhesive resin material whose loss tangent tanδ at -5°C when cured was 0.25 to 0.85. On the other hand, when manufacturing electronic devices using a pre-dicing method, adhesive residue occurred when an adhesive film having an adhesive resin layer made of an ultraviolet-curable adhesive resin material whose loss tangent tanδ at -5°C when cured was less than 0.25 or more than 0.85.

[0096] This application claims priority based on Japanese Patent Application No. 2021-090503, filed on May 28, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0097] 10 Base material layer 20 Adhesive resin layer 30 wafers 30A circuit forming surface 31 chips 50 adhesive film 100 structures

Claims

1. A step (A) of preparing a structure including a wafer having a circuit formation surface and an adhesive film attached to the circuit formation surface side of the wafer; a step (B) of back-grinding the surface of the wafer opposite to the circuit-formed surface; (C) a step of irradiating the adhesive film with ultraviolet light and then removing the adhesive film from the wafer; A method for manufacturing an electronic device comprising at least The adhesive film comprises a base layer and an ultraviolet-curable adhesive resin layer formed on one surface of the base layer using an ultraviolet-curable adhesive resin material, A method for producing an electronic device, wherein the loss tangent tanδ at −5° C. of a cured film of the ultraviolet-curable adhesive resin material is 0.25 to 0.85, as measured as described in the following [Procedure]. [procedure] (i) A film having a thickness of 0.2 mm is formed using the ultraviolet-curable adhesive resin material, and the film is irradiated with ultraviolet light having a dominant wavelength of 365 nm at an irradiation intensity of 100 W / cm using a high-pressure mercury lamp in an environment of 25°C. ２ The UV dose is 1080 mJ / cm ２ The composition is irradiated with UV light to cure it, thereby obtaining a cured film. (ii) The dynamic viscoelasticity of the cured film is measured at a frequency of 1 Hz in a tensile mode at temperatures ranging from -50 to 200°C.

2. 2. A method for manufacturing an electronic device according to claim 1, comprising: The step (A) At least one step (A1) selected from a step (A1-1) of half-cutting the wafer and a step (A1-2) of irradiating the wafer with a laser to form a modified layer on the wafer; After the step (A1), a step (A2) of attaching the adhesive film to the circuit-formed surface of the wafer; A method for manufacturing an electronic device, comprising:

3. 3. A method for manufacturing an electronic device according to claim 1 or 2, comprising: In the step (C), 200 mJ / cm ２ More than 2000mJ / cm ２ The adhesive resin layer is photo-cured by irradiating it with ultraviolet light at a dose below 1000 kJ / cm 2 to reduce the adhesive strength of the adhesive resin layer, and then the adhesive film is removed from the wafer.

4. A method for manufacturing an electronic device according to any one of claims 1 to 3, comprising: The adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule, and a photoinitiator.

5. A method for manufacturing an electronic device according to any one of claims 1 to 4, comprising: The method for manufacturing an electronic device, wherein the adhesive resin layer has a thickness of 5 μm or more and 300 μm or less.

6. A method for manufacturing an electronic device according to any one of claims 1 to 5, comprising: A method for manufacturing an electronic device, wherein the resin constituting the base layer contains one or more selected from the group consisting of polyolefin, polyester, polyamide, poly(meth)acrylate, polyvinyl chloride, polyvinylidene chloride, polyimide, polyetherimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene ether.

7. A method for manufacturing an electronic device according to any one of claims 1 to 6, comprising the steps of: The storage modulus E' at 5°C of the cured film of the ultraviolet-curable adhesive resin material measured as described in the above [Procedure] is 2.0 × 10 ７ ~5.0 x 10 ８ A method for manufacturing an electronic device.

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