Method for manufacturing an electronic device

Abstract

A method for producing an electronic device, the method comprising at least: a step (A) for preparing a structure that is provided with a wafer having a circuit formation surface and an adhesive film that is bonded to a circuit formation surface side of an electronic component; a step (B) for back-grinding a surface of the wafer, the surface being on the reverse side from the circuit formation surface; and a step (C) for irradiating the adhesive film with ultraviolet light, and subsequently removing the adhesive film from the wafer. The adhesive film comprises: a base material layer; and an ultraviolet curable adhesive resin layer which is formed on one surface of the base material layer with use of an ultraviolet curable adhesive resin material. With respect to the step (C), the loss tangent tanδ at -5°C of the adhesive resin layer of the adhesive film after irradiation of ultraviolet light is from 0.25 to 0.85 as determined under the conditions described below. (Conditions: The dynamic viscoelasticity is measured at a frequency of 1 Hz in a tensile mode over a temperature range from -50°C to 200°.)

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electronic device. Specifically, it relates to a method for manufacturing an electronic device using an adhesive film.

Background Art

[0002] In the manufacturing process of an electronic device, in the process of grinding a wafer, an adhesive film may be attached to the circuit formation surface of the wafer in order to fix the wafer or prevent damage to the wafer. As such an adhesive film, generally, a film in which an adhesive resin layer is laminated on a base film is used.

[0003] With the progress of high-density mounting technology, there is a demand for thinning of semiconductor wafers and the like, and for example, it is required to thinly grind a wafer to a thickness of 50 μm or less. As one of such thin grinding processes, there is a pre-dicing method in which a groove having a predetermined depth is formed on one side of a wafer before grinding the wafer, and then the wafer is diced by performing grinding. Also, there is a pre-stealth method in which a modified region is formed by irradiating a laser inside the wafer before grinding, and then the wafer is diced by performing grinding.

[0004] As technologies related to adhesive films suitable for application to such pre-dicing methods and pre-stealth methods, for example, the technologies described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-75560) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2016-72546) can be mentioned.

[0005] Patent Document 1 describes a surface protection sheet having an adhesive layer on a base material, which satisfies the following requirements (a) to (d). (a) The Young's modulus of the base material is 450 MPa or more (b) The storage elastic modulus of the adhesive layer at 25°C is 0.10 MPa or more (c) The storage elastic modulus of the adhesive layer at 50°C is 0.20 MPa or less (d) The thickness of the adhesive layer is 30 μm or more. Patent Document 1 describes that such a surface protection sheet can suppress the intrusion of water (sludge intrusion) from the gap formed when the workpiece is cut and broken into the protected surface of the workpiece during the back grinding process of the workpiece, thereby preventing contamination of the protected surface of the workpiece.

[0006] Patent Document 2 describes a pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer, which has a base resin film and a radiation-curable pressure-sensitive adhesive layer formed on at least one side of the base resin film. The base resin film has at least one rigid layer with a tensile elastic modulus of 1 to 10 GPa, and the peel force at a peel angle of 30° after radiation-curing the pressure-sensitive adhesive layer is 0.1 to 3.0 N / 25 mm. Patent Document 2 states that according to such a pressure-sensitive adhesive tape for protecting the surface of a semiconductor wafer, in the back grinding process of a semiconductor wafer to which the pre-dicing method or the pre-stealth method is applied, the kerf shift of the diced semiconductor chips can be suppressed, and the semiconductor wafer can be processed without being damaged or contaminated.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to the studies by the present inventors, for example, in the manufacturing process of an electronic device, when peeling an adhesive film from a wafer after a back grinding process, it has been revealed that adhesive residue is likely to occur on the dicing street (scribe line) on the wafer side. In particular, in the manufacturing process of an electronic device using a pre-dicing method, a pre-stealth method, etc., when peeling an adhesive film from a wafer (singulated chip) after a back grinding process, it has been revealed that adhesive residue is likely to occur on the wafer side. Specifically, in the pre-dicing method, since an adhesive film is attached to one surface of a wafer provided with grooves on one surface, adhesive residue is likely to occur in the grooves and / or in the vicinity of the grooves. In particular, since the grooves are usually cut using a blade, minute chipping is likely to occur in the grooves, which is considered to be one of the causes of the occurrence of adhesive residue. Also in the pre-stealth method, when peeling an adhesive film from a singulated wafer (chip), it is considered that adhesive residue is likely to occur at the chip end.

[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 singulated chip) after a back grinding process in the manufacture of an electronic device.

Means for Solving the Problem

[0010] As a result of various studies, the present inventors have completed the invention provided below and solved the above 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 bonded to the circuit formation surface side of the electronic component; A step (B) of back grinding the surface of the wafer opposite to the circuit formation surface side; A step (C) of irradiating the adhesive film with ultraviolet rays and then removing the adhesive film from the wafer; A method for manufacturing an electronic device comprising at least The pressure-sensitive adhesive film includes a base material layer and a pressure-sensitive adhesive resin layer of an ultraviolet curable type provided on one surface side of the base material layer using an ultraviolet curable pressure-sensitive adhesive resin material. In the step (C), a method for manufacturing an electronic device in which the loss tangent tanδ at -5°C of the pressure-sensitive adhesive resin layer of the pressure-sensitive adhesive film after irradiation with ultraviolet rays, measured under the following conditions, is 0.25 to 0.85. (Condition) Measure the dynamic viscoelasticity in the range of temperature -50 to 200°C in a tensile mode at a frequency of 1 Hz. 2. In the method for manufacturing an electronic device according to 1., The step (A) is At least one step (A1) selected from the step (A1-1) of half-cutting the wafer and the 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 pressure-sensitive adhesive film to the circuit formation surface side of the electronic component, A method for manufacturing an electronic device including 3. In the method for manufacturing an electronic device according to 1. or 2., In the step (C), the pressure-sensitive adhesive film is irradiated with ultraviolet rays having a dose of 200 mJ / cm 2 or more and 2000 mJ / cm 2 or less to photocure the pressure-sensitive adhesive resin layer and reduce the adhesive force of the pressure-sensitive adhesive resin layer, and then the pressure-sensitive adhesive film is removed from the wafer. 4. In the method for manufacturing an electronic device according to any one of 1. to 3., The pressure-sensitive adhesive resin layer includes a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule and a photoinitiator. 5. In the method for manufacturing an electronic device according to any one of 1. to 4., A method for manufacturing an electronic device, wherein the thickness of the pressure-sensitive adhesive resin layer is 5 μm or more and 300 μm or less. 6. In the 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 base material 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., In the step (C), the storage elastic modulus E' of the pressure-sensitive adhesive resin layer of the pressure-sensitive adhesive film after irradiation with ultraviolet rays, measured under the above conditions, at 5°C is 2.0×10 7 ~5.0×10 8 Pa. A method for manufacturing an electronic device.

Advantages of the Invention

[0012] By the method for manufacturing an electronic device of the present invention, it becomes possible to suppress adhesive residue when peeling the pressure-sensitive adhesive film from the wafer (or the diced chips) after the back grinding process.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Embodiments for Carrying Out 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 the description thereof will be omitted as appropriate. To avoid complexity, (i) when there are a plurality of identical components within the same drawing, only one of them may be labeled, and not all of them may be labeled, or (ii) particularly from FIG. 2 onwards, components similar to those in FIG. 1 may not be relabeled. All the drawings are for illustrative purposes only. The shape, dimensional ratio, etc. of each member in the drawings do not necessarily correspond to those of actual articles.

[0015] In this specification, the notation "X to Y" in the description of a numerical range represents X or more and Y or less, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".

[0016] In the notation of a group (atomic group) in this specification, a notation that does not indicate whether it is substituted or unsubstituted includes both those having no substituent and those having a substituent. For example, the term "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). The notation "(meth)acryl" in this specification represents a concept that includes both acryl and methacryl. The same applies to similar notations such as "(meth)acrylate". In this specification, the term "organic group" means, unless otherwise specified, an atomic group obtained by removing one or more hydrogen atoms from an organic compound. For example, the term "monovalent organic group" represents an atomic group obtained by removing one hydrogen atom from an arbitrary organic compound. In this specification, the term "electronic device" is used to mean elements, devices, end products, etc. to which the technology of electronics is applied, such as semiconductor chips, semiconductor elements, printed wiring boards, electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, chemical batteries, etc.

[0017] FIG. 1 is a cross-sectional view schematically showing an example of the structure of an adhesive film (adhesive film 50) preferably used in the method for manufacturing an electronic device according to the present 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 material layer 10 and an ultraviolet curable adhesive resin layer 20 (an adhesive resin layer composed of an ultraviolet curable adhesive resin material) provided on one surface side of the base material layer 10. Specific embodiments of these layers will be described later.

[0018] FIG. 2 is a cross-sectional view schematically showing an example of a method for manufacturing an electronic device using the adhesive film 50. The method for manufacturing an electronic device according to this embodiment includes at least the following three steps. (A) A step of preparing a structure 100 including a wafer 30 having a circuit formation surface 30A and an adhesive film 50 bonded to the circuit formation surface 30A side of the wafer 30. (B) A step of backgrinding 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 rays and then removing the adhesive film 50 from the wafer 30. In such a series of steps, it is preferable to use the adhesive film described in this specification 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.

[0019] In the method for manufacturing an electronic device according to this embodiment, the loss tangent tanδ of the adhesive resin layer 20 after irradiation with ultraviolet rays in step (C) at -5°C is 0.25 to 0.85. From the viewpoint of making it less likely to generate more adhesive residue, tanδ is preferably 0.28 or more, more preferably 0.29 or more, and 0.80 or less, more preferably 0.78 or less.

[0020] Note that tanδ can be obtained by measuring the dynamic viscoelasticity in the range of -50 to 200°C at a frequency of 1 Hz and in a tensile mode.

[0021] The relationship between the above-mentioned tanδ and the suppression of adhesive residue can be explained as follows. Just to be on the safe side, the present invention is not limited by the following description.

[0022] Regarding the viscoelasticity of the polymer, the change in frequency is very similar to the change in temperature, and it is known that increasing the frequency and lowering the temperature show the same effect (time-temperature conversion rule). When peeling the adhesive film, the cured film of the pressure-sensitive adhesive resin layer (the pressure-sensitive adhesive resin layer 20 after ultraviolet irradiation) is instantaneously deformed greatly. Therefore, it is considered that the viscoelastic behavior in a larger region of frequency (that is, a lower temperature region) corresponds well to the actual peeling mode. That is, although the peeling of the adhesive film after ultraviolet irradiation is usually performed at room temperature, the inventors have found that the tanδ at -5°C, which is a lower temperature, is closely related to the actual peeling mode. Regarding the chemical structure of the pressure-sensitive adhesive resin layer 20 (cured film) cured by ultraviolet irradiation, there are many unclear points because it is difficult to analyze. However, the fact that the tanδ of the cured film at -5°C exceeds 0.85 is presumed to indicate that the proportion of components that do not contribute to crosslinking in the cured film is large. Such components are considered to induce adhesive residue particularly in the grooves provided in the wafer by the prior dicing method and / or in the vicinity of the grooves. Also, the fact that the tanδ of the pressure-sensitive adhesive resin layer 20 (cured film) cured by ultraviolet irradiation at -5°C is less than 0.25 is presumed to indicate that the energy generated during peeling is difficult to be converted into thermal energy. If the energy generated during peeling is difficult to be converted into thermal energy, stress is excessively concentrated at the corners of the chip and the groove portions of the wafer, and the cured product undergoes cohesive failure at that time, inducing adhesive residue. That is, it is considered that when the tanδ of the pressure-sensitive adhesive resin layer 20 (cured film) cured by ultraviolet irradiation at -5°C is 0.25 to 0.85, it becomes difficult to induce adhesive residue.

[0023] In step (C), the loss tangent tanδ of the pressure-sensitive adhesive resin layer 20 after ultraviolet irradiation can be adjusted to a suitable range, for example, by adjusting the type and blending ratio of the pressure-sensitive adhesive resin, crosslinking agent, and photoinitiator that constitute the pressure-sensitive adhesive resin layer 20, and the type and content ratio of each monomer in the pressure-sensitive adhesive resin. And / or, by controlling the ultraviolet irradiation conditions (for example, ultraviolet dose, irradiation intensity, irradiation time, etc.) in step (C), tanδ can be controlled within the above range. In step (C), the pressure-sensitive adhesive film is irradiated with ultraviolet light at a dose of 200 mJ / cm 2 or more and 2000 mJ / cm 2 or less.

[0024] From a different perspective from tanδ at -5°C, in step (C), the storage modulus E' at 5°C of the pressure-sensitive adhesive resin layer after ultraviolet irradiation, measured by dynamic viscoelasticity measurement under the same conditions as the above tanδ, is preferably 2.0×10 7 to 5.0×10 8 Pa.

[0025] When the storage modulus E' at 5°C is within the above numerical range, residue adhesion is suppressed at a higher level. The relationship between the storage modulus E' at 5°C and the suppression of residue adhesion can be explained as follows. Just to be on the safe side, the present invention is not limited by the following description.

[0026] Regarding the viscoelasticity of polymers, it is known that a change in frequency is very similar to a change in temperature, and increasing the frequency and decreasing the temperature show similar effects (time-temperature superposition principle). When the pressure-sensitive adhesive film is peeled off, the cured film of the pressure-sensitive adhesive resin layer deforms greatly instantaneously. Therefore, it is considered that the viscoelastic behavior in a larger region of frequency (that is, a lower temperature region) corresponds well to the actual peeling mode. That is, although the peeling of the cured pressure-sensitive adhesive film is usually performed at room temperature, it is presumed that the storage modulus E' at 5°C, which is a lower temperature, is closely related to the actual peeling mode. The storage elastic modulus E' at 5°C being more than 5.0×10 8 Pa is presumed to mean that the toughness of the cured film of the pressure-sensitive resin layer is significantly impaired and it is likely to leave glue residue. Also, the storage elastic modulus E' at 5°C being 2.0×10 7 Pa or less is presumed to mean that the interaction between the cured film of the pressure-sensitive resin layer and the adherend is too large and it is difficult to peel off, thus it is likely to leave glue residue. That is, it is considered that when the storage elastic modulus E' at 5°C is 2.0×10 7 ~5.0×10 8 Pa, it becomes more difficult to induce glue residue.

[0027] The lower limit value of E' is preferably 2.5×10 7 Pa or more, more preferably 2.6×10 7 Pa or more, and the upper limit value is preferably 4.0×10 8 Pa or less, more preferably 3.8×10 8 Pa or less.

[0028] Hereinafter, first, each layer constituting the pressure-sensitive adhesive film 50 and the like will be specifically described.

[0029] 1. Pressure-sensitive adhesive film (Base material layer) The base material layer 10 is a layer provided for the purpose of making the handling properties, mechanical properties, heat resistance and other properties of the pressure-sensitive adhesive film 50 better. The base material layer 10 is not particularly limited as long as it has a mechanical strength capable of withstanding the external force applied during wafer processing. For example, a resin film can be mentioned. Examples of the resin constituting the base material layer 10 include, for example, 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 polymetaxylylene adipamide; poly(meth)acrylate ((meth)acrylic resin); polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; polyphenylene ether; polyetheretherketone; polyphenylene ether, etc. One or more selected therefrom can be mentioned. 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 preferable, and one or more selected from polyethylene terephthalate and polyethylene naphthalate are more preferable.

[0030] The base material layer 10 may be a single layer or two or more layers. Also, the form of the resin film used to provide the base material layer 10 may be a stretched film or a film stretched in one axial direction or two axial directions. From the viewpoint of improving the mechanical strength of the base material layer 10, it is preferably a film stretched in one axial direction or two axial directions. From the viewpoint of suppressing the warp of the wafer after grinding, the base material layer 10 is preferably pre-annealed. The base material layer 10 may be surface-treated to improve the adhesiveness with other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coat treatment, etc. may be performed.

[0031] From the viewpoint of obtaining good film properties, the thickness of the base material 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 still more preferably 50 μm or more and 150 μm or less.

[0032] (Adhesive resin layer) The pressure-sensitive adhesive film 50 includes an ultraviolet curable pressure-sensitive adhesive resin layer 20. The pressure-sensitive adhesive resin layer 20 is a layer provided on one surface side of the base material layer 10, and is a layer that comes into contact with and adheres to the circuit formation surface of the wafer when the pressure-sensitive adhesive film 50 is attached to the circuit formation surface of the wafer.

[0033] The pressure-sensitive adhesive resin layer 20 is formed using a suitable ultraviolet curable pressure-sensitive adhesive resin material. Specifically, the pressure-sensitive adhesive resin layer 20 is formed using an ultraviolet curable pressure-sensitive adhesive resin material whose adhesive force decreases when irradiated with ultraviolet rays. When the pressure-sensitive adhesive resin layer 20 is irradiated with ultraviolet rays, it cures (such as crosslinks) and the adhesive force decreases, so it becomes easier to peel the wafer (or the chip obtained by singulating the wafer) from the pressure-sensitive adhesive film 50.

[0034] The ultraviolet curable pressure-sensitive adhesive resin material preferably contains a (meth)acrylic resin known in the fields of adhesives and binders. Examples of the (meth)acrylic resin include homopolymers of (meth)acrylate compounds, copolymers of (meth)acrylate compounds and comonomers, etc. Examples of the (meth)acrylate compound as the raw material monomer include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, etc. These (meth)acrylate compounds may be used alone or in combination of two or more. In addition, examples of the comonomer constituting the (meth)acrylic copolymer include vinyl acetate, (meth)acrylonitrile, styrene, (meth)acrylic acid, itaconic acid, (meth)acrylamide, methylol(meth)acrylamide, maleic anhydride, and the like. When using these comonomers, they may be used alone or in combination of two or more.

[0035] The ultraviolet curable pressure-sensitive adhesive resin material preferably contains a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule (specifically, in the side chain and / or at the terminal), a photoinitiator, and further contains a crosslinking agent or the like as necessary. The ultraviolet curable pressure-sensitive 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).

[0036] The (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule (specifically, in the side chain and / or at the terminal) is specifically 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, a condensation reaction, etc. with the functional group (P) while leaving the double bond in the monomer, and a polymerizable carbon-carbon double bond is introduced into the copolymer molecule.

[0037] Examples of the monomer having an ethylenic double bond include one or more selected from acrylic acid alkyl esters and methacrylic acid alkyl ester monomers such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, and ethyl (meth)acrylate, vinyl esters such as vinyl acetate, and monomers having an ethylenic double bond such as (meth)acrylonitrile, (meth)acrylamide, and styrene.

[0038] Examples of the copolymerizable monomer having the functional group (P) include (meth)acrylic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, N-methylol(meth)acrylamide, (meth)acryloyloxyethyl isocyanate, and the like. 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 the functional group (P) is preferably such that the monomer having an ethylenic double bond is 70 to 99% by mass and the copolymerizable monomer having the functional group (P) is 1 to 30% by mass. More preferably, the monomer having an ethylenic double bond is 80 to 95% by mass and the copolymerizable monomer having the functional group (P) is 5 to 20% by mass. Examples of the monomer having the functional group (Q) include the same monomers as the copolymerizable monomer having the functional group (P) described above.

[0039] 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), a combination of the functional group (P) and the functional group (Q) that reacts, such as a carboxyl group and an epoxy group, a carboxyl group and an aziridinyl group, a hydroxyl group and an isocyanate group, etc., a combination in which an addition reaction easily occurs is desirable. Also, not limited to the addition reaction, any reaction in which a polymerizable carbon-carbon double bond can be easily introduced, such as a condensation reaction between a carboxylic acid group and a hydroxyl group, is applicable. When copolymerizing a monomer having an ethylenic double bond and a copolymerizable monomer having a functional group (P), a polymerization initiator can be used. Examples of the polymerization initiator include radical polymerization initiators such as benzoyl peroxide-based polymerization initiators and t-butyl peroxy-2-ethylhexanoate.

[0040] Examples of the low molecular weight compound having two or more polymerizable carbon-carbon double bonds in the molecule include polyfunctional (meth)acrylate compounds such as tripropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetraacrylate, etc. When using these, only one kind may be used or two or more kinds may be used. The addition amount of the low molecular weight compound having two or more polymerizable carbon-carbon double bonds in the molecule is preferably 0.1 to 20 parts by mass, more preferably 5 to 18 parts by mass with respect to 100 parts by mass of the above (meth)acrylic resin. In addition, the addition amount of the low molecular weight compound having two or more polymerizable carbon-carbon double bonds in the molecule is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, still more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more with respect to 100 parts by mass of the above (meth)acrylic resin, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, still more preferably 15 parts by mass or less, still more preferably 13 parts by mass or less.

[0041] The photoinitiator usually generates chemical species (such as radicals) that polymerize polymerizable carbon-carbon double bonds when irradiated with ultraviolet rays. Examples of the photoinitiator 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.

[0042] Only one type of photoinitiator may be used, or two or more types may be used. The addition amount of the photoinitiator is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and still more preferably 4 to 10 parts by mass with respect to 100 parts by mass of the above (meth)acrylic resin. Also, the addition amount of the photoinitiator is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, still more preferably 3 parts by mass or more, still more preferably 4 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 15 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less with respect to 100 parts by mass of the above (meth)acrylic resin.

[0043] The ultraviolet curable pressure-sensitive adhesive resin material may contain a crosslinking agent. Examples of the crosslinking agent 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 -aziridinylpropionate, trimethylolpropane-tri-β -aziridinylpropionate, 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. Only one type of crosslinking agent may be used, or two or more types may be used.

[0044] When using a crosslinking agent, the amount is preferably in a range such that the number of functional groups in the crosslinking agent does not exceed the number of functional groups in the (meth)acrylic resin. However, in cases where new functional groups are generated by the crosslinking reaction or the crosslinking reaction is slow, etc., it may be contained in excess as necessary. When using a crosslinking agent, the content of the crosslinking agent in the ultraviolet curable pressure-sensitive adhesive resin material is preferably 0.1 part by mass or more and 15 parts by mass or less, more preferably 0.5 part by mass or more and 5 parts by mass or less, with respect to 100 parts by mass of the (meth)acrylic resin, from the viewpoint of improving the balance between the heat resistance and the adhesive strength of the pressure-sensitive adhesive resin layer 20. Also, when using a crosslinking agent, the content of the crosslinking agent in the ultraviolet curable pressure-sensitive adhesive resin material is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, still more preferably 0.5 part by mass or more, and still more preferably 0.7 part by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, and still more preferably 3 parts by mass or less, with respect to 100 parts by mass of the (meth)acrylic resin, from the viewpoint of improving the balance between the heat resistance and the adhesive strength of the pressure-sensitive adhesive resin layer 20.

[0045] The adhesive resin layer 20 can be formed, for example, by applying an ultraviolet curable adhesive resin material onto one surface of the base material 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 each of the above components in a suitable solvent (typically an organic solvent) onto one surface of the base material layer 10. As the coating method, for example, conventionally known coating methods such as a roll coater method, a reverse roll coater method, a gravure roll method, a bar coat method, a comma coater method, a die coater method, etc. can be adopted. The drying conditions are not particularly limited, but generally, it is preferable to dry at a temperature range of 80 to 200°C for 10 seconds to 10 minutes. More preferably, dry at 80 to 170°C for 15 seconds to 5 minutes. In order to sufficiently promote the crosslinking reaction between the crosslinking agent and the (meth)acrylic resin, after the drying of the adhesive coating solution is completed, it may be heated at 40 to 80°C for about 5 to 300 hours.

[0046] As another method different from applying the ultraviolet curable adhesive resin material onto one surface of the base material layer 10, as shown in the examples described later, (i) first, the ultraviolet curable adhesive resin material is applied onto the surface of a peelable base material (separator) to form the adhesive resin layer 20, and (ii) then, the formed adhesive resin layer is bonded to one surface of the base material layer 10.

[0047] 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. Also, 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, and even more preferably 50 μm or less. When the thickness of the adhesive resin layer 20 is moderately large, sufficient adhesiveness can be obtained. Also, since the adhesive resin layer 20 is not too thick, the handleability of the adhesive film 50 is improved.

[0048] (Other Layers) The adhesive film 50 may be provided with other layers as long as the effect of suppressing adhesive residue is not impaired. For example, there may be other layers such as a concavo-convex absorbing resin layer, an adhesive layer, and an antistatic layer between the respective layers. By providing a concavo-convex absorbing resin layer, the concavo-convex absorbability of the adhesive film 50 can be improved. By providing an adhesive layer, the adhesiveness between the respective layers can be improved. Also, by providing an antistatic layer, the antistatic property of the adhesive film 50 can be improved. Also, from the viewpoint of suppressing deterioration and foreign matter adhesion before use, the exposed surface of the pressure-sensitive adhesive resin layer 20 may be protected with a suitable protective film (easily peelable film) such as a release film.

[0049] (Overall Thickness) The thickness of the entire 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, from the balance between mechanical properties and handleability.

[0050] (Decrease in Adhesive Force due to Ultraviolet Exposure) As described above, in the adhesive film 50, the pressure-sensitive adhesive resin layer 20 is formed using a UV-curable pressure-sensitive adhesive resin material whose adhesive force decreases due to ultraviolet rays. The degree to which the adhesive force decreases due to ultraviolet rays is preferably quantified as follows.

[0051] · Let the peel strength when a peel test is performed under the conditions of a peel angle of 180° and a peel speed of 300 mm / min after bonding the pressure-sensitive adhesive resin layer 20 of the adhesive film 50 to a mirror-polished silicon wafer and leaving it for 1 hour be F0. · Let the peel strength when a peel test is performed under the conditions of a peel angle of 180° and a peel speed of 300 mm / min after bonding the pressure-sensitive adhesive resin layer 20 of the adhesive film 50 to a mirror-polished silicon wafer and irradiating it with ultraviolet rays having a wavelength of 365 nm at 1080 mJ / cm 2 be F1. ·F1 / F0 is preferably from 0.01 to 0.60, more preferably from 0.01 to 0.20, and even more preferably from 0.02 to 0.20. Also, F1 / F0 is preferably 0.01 or more, more preferably 0.015 or more, and even 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, and even more preferably 0.12 or less.

[0052] When F1 / F0 is an appropriate value, the intrusion of grinding water between the wafer and the tape during the backgrinding process is suppressed, and the peeling of the adhesive film 50 becomes easier after the backgrinding process.

[0053] Incidentally, the value of F0 itself is, for example, 3 to 20 N / 25 mm, specifically 3 to 16 N / 25 mm. Also, the value of F1 itself is, for example, 10 N / 25 mm or less, specifically 1 N / 25 mm or less, and 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.

[0054] Next to the adhesive film, a method for manufacturing an electronic device will be described.

[0055] 2. Method for manufacturing an electronic device The method for manufacturing an electronic device according to this embodiment includes at least the aforementioned steps (A), (B), and (C). Hereinafter, each step will be specifically described with reference to FIG. 2.

[0056] (Step (A)) First, a structure 100 including a wafer 30 having a circuit formation surface 30A and an adhesive film 50 bonded to the circuit formation surface 30A side of the wafer 30 is prepared. Such a structure 100 can be manufactured, for example, by peeling a 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.

[0057] The conditions for attaching the circuit formation surface 30A of the wafer 30 to the adhesive film 50 are not particularly limited. For example, the temperature can be 20 - 80°C, the pressure can be 0.05 - 0.5 MPa, and the attachment speed can be 0.5 - 20 mm / second.

[0058] Step (A) preferably further includes at least one step (A1) selected from a step (A1-1) of half-cutting the wafer 30 and a step (A1-2) of irradiating the wafer 30 with a laser to form a modified layer on the wafer 30, and a step (A2) of attaching a backgrinding adhesive film 50 to the circuit formation surface 30A side of the wafer 30 after the step (A1). As described above, the manufacturing method of the electronic device of the present embodiment is preferably applied to the manufacturing process of an electronic device using a pre-dicing method, a pre-stealth method, or the like. Therefore, a manufacturing method that performs the above step (A1-1) for the pre-dicing method or the above step (A1-2) for the pre-stealth method is preferred.

[0059] In step (A2), the adhesive film 50 can be heated and attached to the circuit formation surface 30A of the wafer 30. Thereby, the adhesion state between the adhesive resin layer 20 and the wafer 30 can be made good over a long period of time. The heating temperature is not particularly limited, but is, for example, 60 - 80°C.

[0060] The operation of attaching the adhesive film 50 to the wafer 30 may be performed manually, but generally can be performed by a device called an automatic attaching machine equipped with a roll-shaped adhesive film.

[0061] The wafer 30 to be attached to the adhesive film 50 is not particularly limited, but it is preferably a wafer 30 having a circuit formation surface 30A. For example, a semiconductor wafer, an epoxy mold wafer, an epoxy mold panel, etc. may be mentioned, and preferably a semiconductor wafer and an epoxy mold wafer. Further, as the semiconductor wafer, for example, a silicon wafer, a sapphire wafer, a germanium wafer, a germanium-arsenic wafer, a gallium-phosphorus wafer, a gallium-arsenic-aluminum wafer, a gallium-arsenic wafer, a lithium tantalate wafer, etc. may be mentioned, and it is preferably used for a silicon wafer. As the epoxy mold wafer, a wafer manufactured by an eWLB (Embedded Wafer Level Ball Grid Array) process, which is one of the manufacturing methods of the fan-out type WLP, may be mentioned. The semiconductor wafer and the epoxy mold wafer having a circuit formation surface are not particularly limited, and for example, those having circuits such as wiring, capacitors, diodes, or transistors formed on the surface may be mentioned. Further, the circuit formation surface may be plasma-treated.

[0062] The circuit formation surface 30A of the wafer 30 may be an uneven surface, for example, by having bump electrodes or the like. The bump electrode is, for example, joined to an electrode formed on the mounting surface when mounting an electronic device on the mounting surface, and forms an electrical connection between the electronic device and the mounting surface (mounting surface of a printed circuit board or the like). Examples of the bump electrode include ball bumps, printed bumps, stud bumps, plated bumps, pillar bumps, etc. That is, the bump electrode is usually a convex electrode. These bump electrodes may be used alone or in combination of two or more. The height and diameter of the bump electrode are not particularly limited, but are preferably 10 to 400 μm, more preferably 50 to 300 μm, respectively. Also, the bump pitch at that time is not particularly limited, but is preferably 20 to 600 μm, more preferably 100 to 500 μm. The metal species constituting the bump electrodes is not particularly limited, and examples thereof include solder, silver, gold, copper, tin, lead, bismuth, and alloys thereof. However, the adhesive film 50 is preferably used when the bump electrodes are solder bumps. These metal species may be used alone or in combination of two or more.

[0063] (Step (B)) Next, the surface (also referred to as the back surface) on the side opposite to the circuit formation surface 30A side of the wafer 30 is backgrinded. "Backgrinding" means thinning the wafer 30 to a predetermined thickness without damaging it. For example, the structure 100 is fixed to a chuck table of a grinding machine or the like, and the back surface (non-circuit formation surface) of the wafer 30 is ground.

[0064] In such a back surface grinding operation, the wafer 30 is ground until its thickness becomes equal to or less than the desired thickness. The thickness of the wafer 30 before grinding is appropriately determined according to the diameter, type, etc. of the wafer 30, and the thickness of the wafer 30 after grinding is appropriately determined according to the size of the obtained chip, the type of circuit, etc. Also, when the wafer 30 is half-cut or a modified layer is formed by laser irradiation, as shown in FIG. 1, the wafer 30 can be singulated into chips 31 by step (B).

[0065] The back surface grinding method is not particularly limited, and a known grinding method can be adopted. Grinding can be performed while cooling by applying water to the wafer 30 and the grindstone. If necessary, a dry polish process, which is a grinding method without using grinding water at the end of the grinding process, can be performed. After the back grinding is completed, chemical etching is performed as necessary. Chemical etching is performed by immersing the wafer 30 in an etching solution selected from the group consisting of an acidic aqueous solution composed 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, with the adhesive film 50 attached. Etching is performed for the purpose of removing the distortion generated on the back surface of the wafer 30, further thinning the wafer 30, removing an oxide film, etc., and pre-treatment when forming an electrode on the back surface. The etching solution is appropriately selected according to the above purposes.

[0066] (Step (C)) Next, the adhesive film 50 is irradiated with ultraviolet rays, and then the adhesive film 50 is removed from the wafer 30. In step (C), for the adhesive film 50, for example, ultraviolet rays with a dose of 200 mJ / cm 2 or more and 2000 mJ / cm 2 or less are irradiated to cure the pressure-sensitive adhesive resin layer 20 with ultraviolet rays to reduce the adhesive force of the pressure-sensitive adhesive resin layer 20, and then the adhesive film 50 is removed from the wafer 30. The ultraviolet irradiation can be performed using ultraviolet rays with a main wavelength of 365 nm using, for example, a high-pressure mercury lamp. The irradiation intensity of the ultraviolet rays is, for example, 50 mW / cm 2 or more and 500 mW / cm 2 or less.

[0067] 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 generally can be performed by a device called an automatic peeling machine. After peeling off the adhesive film 50, the surface of the wafer 30 may be washed as necessary. Examples of the washing method include wet washing such as water washing and solvent washing, and dry washing such as plasma washing. In the case of wet washing, ultrasonic washing may be used in combination. The washing method can be appropriately selected according to the contamination situation of the surface of the wafer 30.

[0068] (Other processes) After performing steps (A) to (C), steps such as mounting the obtained chip 31 on a circuit board may be further performed. These steps can be carried out based on known information.

[0069] As described above, the embodiments of the present invention have been described, but these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope capable of achieving the object of the present invention are included in the present invention.

Example

[0070] The embodiments of the present invention will be described in detail based on examples and comparative examples. Just to be clear, the present invention is not limited only to the examples. In the examples, exponential notation may be indicated by the symbol "E". For example, the notation 1.3E+06 means 1.3×10 6 means.

[0071] <Preparation of raw materials> The following raw materials were prepared.

[0072] (Base material layer) Base material layer 1: Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E7180, thickness: 50 μm, one-sided corona-treated product)

[0073] Base material layer 2: A laminated film composed of a low-density polyethylene film / polyethylene terephthalate film / low-density polyethylene film manufactured as follows (total thickness: 110 μm) A low-density polyethylene film (density: 0.925 kg / m 3 ; thickness: 30 μm) was laminated on both sides of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name: Lumirror S10, thickness: 50 μm). Corona treatment was performed on one side of the obtained laminated film.

[0074] Base material layer 3: A laminated film (total thickness: 145 μm) composed of a polyethylene terephthalate film / ethylene-vinyl acetate copolymer film / acrylic film, manufactured as follows A polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E7180, thickness: 50 μm) and an ethylene-vinyl acetate copolymer (manufactured by Mitsui Dow Chemical Co., Ltd., MFR: 2.5 g / 10 min) film (thickness: 70 μm) were laminated by performing corona treatment on the bonding surface side of the ethylene-vinyl acetate copolymer film with the polyethylene terephthalate film. Further, corona discharge treatment was also performed on the opposite surface side of the polyethylene terephthalate film of the ethylene-vinyl acetate copolymer film. Next, an acrylic resin coating solution for the base material layer shown below was coated and dried to a dry thickness of 20 μm on the release surface of a release-treated polyethylene terephthalate film (separator), and laminated onto the laminated film composed of the above polyethylene terephthalate film / ethylene-vinyl acetate copolymer film through the ethylene-vinyl acetate copolymer film, and aged (40 °C, 3 days). Then, the separator was peeled off. The base material layer 3 was obtained as described above.

[0075] (Acrylic resin coating solution for the base material layer) Using 0.5 parts by mass of 4,4'-azobis-4-cyanovaleric acid (manufactured by Otsuka Chemical Co., Ltd., product name: ACVA) as a polymerization initiator, 74 parts by mass of butyl acrylate, 14 parts by mass of methyl methacrylate, 9 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, and 3 parts by mass of an aqueous solution of ammonium polyoxyethylene nonylpropenyl phenyl ether sulfate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) were emulsion polymerized in deionized water at 70 °C for 9 hours. After the polymerization was completed, the pH was adjusted to 7 with aqueous ammonia to obtain an acrylic polymer aqueous emulsion having a solid content concentration of 42.5% by mass. Next, using aqueous ammonia, the pH of 100 parts by mass of this acrylic polymer aqueous emulsion was adjusted to 9 or more, and 0.75 parts by mass of an aziridine-based crosslinking agent [manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd., Chemitec PZ-33] and 5 parts by mass of diethylene glycol monobutyl ether were blended. As described above, an acrylic resin coating solution for the base material layer was obtained.

[0076] ((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 (in terms of solid content) of a benzoyl peroxide-based polymerization initiator as a 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 the reaction was completed, the obtained 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, and the reaction was carried out at 85 °C for 32 hours while blowing air. As described above, (meth)acrylic resin solution 1 was obtained.

[0077] (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-butyl peroxy-2-ethylhexanoate as a polymerization initiator were reacted at 85 °C for 10 hours in a mixed solvent of 20 parts by mass of toluene and 80 parts by mass of ethyl acetate. After the reaction was completed, the obtained solution was cooled, and 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 were added thereto, and the mixture was reacted at 85 °C for 12 hours while blowing air. In this way, the (meth)acrylic resin solution 2 was obtained.

[0078] (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 (in terms of solid content) of a benzoyl peroxide-based polymerization initiator as a polymerization initiator were reacted at 80 °C for 9 hours in a mixed solvent of 7 parts by mass of toluene and 50 parts by mass of ethyl acetate. After the reaction was completed, the obtained solution was cooled, and 25 parts by mass of toluene was added to the cooled solution. In this way, the (meth)acrylic resin solution 3 was obtained.

[0079] (Photoinitiator) Omnirad 651 (manufactured by IGM): 2,2-dimethoxy-2-phenylacetophenone Omnirad 369 (manufactured by IGM): 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone

[0080] (Polyfunctional (meth)acrylate) Aronix M400 (manufactured by Toagosei Co., Ltd.): A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate

[0081] (Crosslinking agent) Isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name: Orestar P49-75S)

[0082] <Preparation of Ultraviolet-Curable Pressure-Sensitive Adhesive Resin Material (Coating Liquid for Forming Pressure-Sensitive Adhesive Resin Layer)> Each material described in the column of "Ultraviolet-Curable Pressure-Sensitive Adhesive Resin Material (Coating Liquid for Forming Pressure-Sensitive Adhesive Resin Layer)" in Table 1 was uniformly mixed to obtain an ultraviolet-curable pressure-sensitive adhesive resin material (coating liquid for forming a pressure-sensitive adhesive resin layer).

[0083] <Fabrication of Pressure-Sensitive Adhesive Film> First, the ultraviolet-curable pressure-sensitive adhesive resin material (coating liquid for forming a pressure-sensitive adhesive resin layer) described in Table 1 was applied to a silicone-release-treated polyethylene terephthalate film (separator). Then, it was dried at 120 °C for 3 minutes to form a pressure-sensitive adhesive resin layer with a thickness of 20 μm. The formed pressure-sensitive adhesive resin layer was laminated to a base material layer to form a laminate. Specifically, when using Base Material Layer 1 or 2 as the base material layer, it was laminated to the corona-treated surface. When using Base Material Layer 3 as the base material layer, the separator was peeled off and laminated to the acrylic film layer side. The obtained laminate was heated in an oven at 40 °C for 3 days for aging. Thus, a pressure-sensitive adhesive film for backgrinding was obtained.

[0084] <Confirmation of Basic Physical Properties> (1) Adhesion Evaluation: Measurement of Adhesion Before and After Ultraviolet Irradiation (i) Preparation of Adherend Wafer for Adhesion Measurement: The mirror surface of a silicon mirror wafer (manufactured by SUMCO, 4-inch single-sided mirror wafer) was ozone-cleaned (ozone treatment time: 60 seconds) using a UV ozone cleaning device (manufactured by Technovision, UV-208). Then, the wafer mirror surface wiped with ethanol was used as the adherend wafer.

[0085] (ii) Measurement of Adhesion Before Ultraviolet Irradiation: In an environment of 23 °C and 50% RH, the pressure-sensitive adhesive film obtained in <Fabrication of Pressure-Sensitive Adhesive Film> was cut to a width of 50 mm, the separator was peeled off, and using a hand roller, the pressure-sensitive adhesive film was attached to the mirror surface of the adherend wafer through its pressure-sensitive adhesive resin layer. Then, it was left for 1 hour. After placement, using a tensile testing machine (Shimadzu Corporation, product name: Autograph AGS-X), one end of the adhesive film was clamped, and the adhesive film was peeled from the surface of the adherend wafer at a peeling angle of 180° and a peeling speed of 300 mm / min. The stress at this time was measured and converted to N / 25 mm to obtain the adhesive force. The evaluation was carried out with N = 2, and the two obtained values were averaged to obtain the peeling strength F0.

[0086] (iii) Measurement of adhesive force after ultraviolet irradiation: In an environment of 23°C and 50% RH, the adhesive film for adhesive force evaluation was cut to a width of 50 mm, the separator was peeled off, and using a hand roller, the adhesive film was attached to the mirror surface of the adherend wafer through its adhesive resin layer. Then, it was left for 1 hour. After leaving, in an environment of 25°C, using a high-pressure mercury lamp, ultraviolet light with a main wavelength of 365 nm was irradiated on the adhesive film at an irradiation intensity of 100 mW / cm 2 with an ultraviolet dose of 1080 mJ / cm 2 Then, using a tensile testing machine (Shimadzu Corporation, product name: Autograph AGS-X), one end of the adhesive film was clamped, and the adhesive film was peeled from the surface of the adherend wafer at a peeling angle of 180° and a peeling speed of 300 mm / min. The stress at this time was measured and converted to N / 25 mm to obtain the adhesive force. The evaluation was carried out with N = 2, and the two obtained values were averaged to obtain the peeling strength F1. Then, from the obtained numerical values of F1 and F0, F1 / F0 was calculated.

[0087] (2) Glue residue evaluation In the above (iii), the adherend wafer after ultraviolet peeling was visually observed to judge the presence or absence of glue residue. When no glue residue was confirmed, it was marked as "none" in Table 1.

[0088] <Various evaluations in the previous dicing method> (1) Preparation of evaluation wafers Evaluation wafer 1: Using a dicing saw, the mirror surface of a mirror wafer (manufactured by KST World, 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 35 μm.

[0089] Evaluation Wafer 2: Using a dicing saw, a first-stage half-cut was performed on the mirror surface of a mirror wafer (manufactured by KST World, 8-inch mirror wafer, diameter: 200 ± 0.5 mm, thickness: 725 ± 50 μm, single-sided mirror) (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). When observed with an optical microscope, the kerf width was 60 μm. Subsequently, a second-stage 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 / second, attachment pressure: 0.36 MPa). Subsequently, using a grinder (DGP8760 manufactured by DISCO), the back surface of the above wafer was ground (rough grinding and precision grinding, precision grinding amount: 40 μm, no polish, thickness after grinding: 38 μm) and diced.

[0091] Thereafter, UV irradiation and peeling of the adhesive film were performed to evaluate the device peelability and residue after the pre-dicing method. Regarding UV irradiation, specifically, in an environment of 25°C, using a high-pressure mercury lamp, ultraviolet light with a main wavelength of 365 nm was irradiated at an irradiation intensity of 100 mW / cm 2 to the pressure-sensitive adhesive film with an ultraviolet dose of 1080 mJ / cm 2 . The peeling of the pressure-sensitive adhesive film was performed according to the following procedure. First, using a wafer mounter (manufactured by Nitto Denko Corporation, MSA300), a separately prepared dicing tape (used as a mounting tape) was attached to the wafer side of an 8-inch wafer ring frame and the above-mentioned diced wafer through the adhesive surface of the dicing tape. Subsequently, using a tape peeling machine (manufactured by Nitto Denko Corporation, HR3000III), the pressure-sensitive adhesive film for pre-dicing evaluation was peeled from the wafer notch part with a peeling tape (manufactured by Rusting System Corporation, PET38REL). Then, the device peelability was evaluated. In Table 1, the case where the pressure-sensitive adhesive film for pre-dicing evaluation could be peeled from the wafer at once was described as "OK".

[0092] In addition, the glue residue on the diced wafer after the pre-dicing method was observed and evaluated using an optical microscope (manufactured by Olympus Corporation). In the observation, in particular, it was observed whether there was no filamentous glue residue in the portion where the groove was provided in advance. In Table 1, the case where no glue residue was confirmed was described as "OK", and the case where there was glue residue was described as "present".

[0093] Note that a pressure-sensitive adhesive film after UV irradiation under the above conditions cut into a width of 10 mm and a length of 50 mm was used as a measurement sample, and the viscoelastic properties of the pressure-sensitive adhesive resin layer in the pressure-sensitive adhesive film after UV irradiation were measured. Specifically, using a solid viscoelasticity measuring device (manufactured by TA Instruments, RSA3), the measurement sample was set in the device so that the distance between the chucks was 20 mm, and it was measured in a temperature range of -50 to 200°C at a frequency of 1 Hz in a tensile mode. Then, the loss tangent tanδ at -5°C and the storage elastic modulus E' at 5°C were obtained.

[0094] Various information is summarized and shown in Table 1. The unit of E' is Pa.

[0095]

Table 1

[0096] As shown in Table 1, by appropriately adjusting the composition of the adhesive resin layer, the ultraviolet irradiation conditions, etc., so that the loss tangent tanδ at -5°C of the adhesive resin layer after ultraviolet irradiation is 0.25 to 0.85, the occurrence of adhesive residue after the implementation of the prior dicing method was suppressed. On the other hand, when the loss tangent tanδ at -5°C of the adhesive resin layer after ultraviolet irradiation was less than 0.25 or more than 0.85, adhesive residue occurred after the implementation of the prior dicing method.

[0097] This application claims the priority based on Japanese Patent Application No. 2021-090244 filed on May 28, 2021, and incorporates all of its disclosures herein.

Explanation of Reference Numerals

[0098] 10 Substrate layer 20 Adhesive resin layer 30 Wafer 30A Circuit formation surface 31 Chip 50 Adhesive film 100 Structure

Claims

1. A step (A) of preparing a structure including a wafer having a circuit formation surface and an adhesive film bonded to the circuit formation surface side of the wafer; A step (B) of backgrinding the surface of the wafer opposite to the circuit formation surface side; A step (C) of irradiating the adhesive film with ultraviolet rays and then removing the adhesive film from the wafer; A method for manufacturing an electronic device comprising at least: The adhesive film includes a base material layer and an ultraviolet curable adhesive resin layer provided on one surface side of the base material layer using an ultraviolet curable adhesive resin material; In the step (C), a method for manufacturing an electronic device in which the loss tangent tan δ at -5°C of the adhesive resin layer of the adhesive film after irradiation with ultraviolet rays, measured under the following conditions, is 0.25 to 0.

85. (Conditions) Measure the dynamic viscoelasticity in the temperature range of -50 to 200°C in a tensile mode at a frequency of 1 Hz.

2. In the method for manufacturing an electronic device according to Claim 1, The step (A) is 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 formation surface side of the wafer; A method for manufacturing an electronic device including.

3. In the method for manufacturing an electronic device according to Claim 1 or 2, In the step (C), ultraviolet rays with a dose of 200 mJ / cm ２ or more and 2000 mJ / cm ２ or less are irradiated onto the adhesive film to photocure the adhesive resin layer and reduce the adhesive force of the adhesive resin layer, and then the adhesive film is removed from the wafer. A method for manufacturing an electronic device.

4. In the method for manufacturing an electronic device according to Claim 1 or 2, The adhesive resin layer includes a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule and a photoinitiator. A method for manufacturing an electronic device.

5. In the method for manufacturing an electronic device according to Claim 1 or 2, A method for manufacturing an electronic device in which the thickness of the adhesive resin layer is 5 μm or more and 300 μm or less.

6. In the method for manufacturing an electronic device according to Claim 1 or 2, A method for manufacturing an electronic device, wherein the resin constituting the base material 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 claim 1 or 2, wherein In the step (C), the storage elastic modulus E' at 5°C of the pressure-sensitive resin layer of the pressure-sensitive film after irradiation with ultraviolet rays, measured under the above conditions, is 2.0×10 ７ to 5.0×10 ８ Pa. A method for manufacturing an electronic device.

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