TWI896705B - Method for producing electronic device - Google Patents

Abstract

A manufacturing method of an electronic device, at least including: step (A), preparing a structure (100), the structure (100) includes an electronic component (30) having a circuit forming surface (30A) and an adhesive film (50) attached to the circuit forming surface (30A) side of the electronic component (30); step (B), back-grinding the surface of the electronic component (30) on the opposite side to the circuit forming surface (30A) side; and step (C), removing the adhesive film (50) from the electronic component (30) after irradiating the adhesive film (50) with ultraviolet rays, wherein the adhesive film (50) includes a substrate layer (10) and an ultraviolet curable adhesive resin layer (20) provided on one side of the substrate layer (10), and a 60° peel strength of the adhesive film (50) after ultraviolet irradiation measured by the following method is 0.4 N/25 mm or more and 5.0 N/25 mm or less. (Method) Attach the adhesive film (50) to a silicon mirror wafer in such a way that the adhesive resin layer (20) is in contact with the silicon mirror wafer. Then, at a temperature of 25°C, use a high-pressure mercury lamp with an irradiation intensity of 100 mW/cm² to irradiate the adhesive resin layer (20) by ultraviolet rays with a dominant wavelength of 365 nm having an amount of 1080 mJ/cm² to harden the adhesive resin layer (20). Then, using a tensile testing machine, peel the adhesive film (50) from the silicon mirror wafer along a 60° direction at 23°C and a speed of 150 mm/min, and the strength at this time (N/25 mm) is taken as the 60° peel strength.

Description

Method for manufacturing electronic device

The present invention relates to a method for manufacturing an electronic device.

During the polishing process of electronic components during the manufacturing process of electronic devices, adhesive films are attached to the circuit-forming surface of electronic components to secure them or prevent damage.

Such adhesive films typically use a base film with an adhesive resin layer laminated on it.

With the advancement of high-density packaging technology, there is a demand for thinner electronic components such as semiconductor wafers, requiring them to be processed to a thickness of, for example, 50μm or less.

One method of this thinning process involves cutting ahead, where grooves of a predetermined depth are formed on the surface of the electronic component before polishing, and then the components are singulated by polishing. Another method involves creating a modified area within the electronic component by irradiating it with a laser before polishing, and then singulating the components by polishing.

Technologies related to adhesive films used in such pre-cutting and pre-cloaking methods include those described in Patent Document 1 (Japanese Patent Publication No. 2014-75560) and Patent Document 2 (Japanese Patent Publication No. 2016-72546).

Patent Document 1 describes a surface protection sheet having an adhesive layer on a substrate and meeting the following requirements (a) to (d).

(a) The Young's modulus of the substrate is 450 MPa or greater.

(b) The storage elastic coefficient of the adhesive layer at 25°C is greater than 0.10 MPa.

(c) The storage elastic coefficient of the adhesive layer at 50°C is less than 0.20 MPa.

(d) The thickness of the adhesive layer is greater than 30 μm.

Patent Document 1 describes this surface protection sheet as preventing water from penetrating the workpiece's protected surface (mud infiltration) through gaps created by cutting the workpiece during back grinding, thereby preventing contamination of the workpiece's protected surface.

Patent Document 2 describes an adhesive tape for protecting the surface of a semiconductor wafer. The tape 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 includes at least one rigid layer having a tensile modulus of elasticity of 1 GPa to 10 GPa. After radiation curing, the adhesive layer exhibits a peel force of 0.1 N/25 mm to 3.0 N/25 mm at a peel angle of 30°.

Patent Document 2 describes that this semiconductor wafer surface protective adhesive tape can suppress deviation of scribe marks on singulated semiconductor wafers during the backside grinding step of semiconductor wafers using a dicing-first or stealth-first method, while also enabling processing without damaging or contaminating the semiconductor wafers.

[Prior Art Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 2014-75560

Patent Document 2: Japanese Patent Publication No. 2016-72546

Research by the inventors has revealed that, in electronic device manufacturing processes using methods such as dicing-first or cover-first, adhesive residue is likely to form on the electronic component side when the adhesive film is peeled off from the electronic component after the backside grinding step.

The present invention was developed in view of the above situation and provides a method for manufacturing electronic devices that can suppress adhesive residue on the electronic component side when peeling the adhesive film from the electronic component after the back grinding step.

The inventors of the present invention have conducted extensive research to achieve this goal. They discovered that by adjusting the 60° peel strength of the adhesive film after UV irradiation within a specific range, it is possible to suppress adhesive residue on the electronic component side when peeling the adhesive film from the electronic component after the back grinding step.

According to the present invention, a method for manufacturing an electronic device as shown below is provided.

[1]

A method for manufacturing an electronic device comprises at least: step (A) of preparing a structure comprising an electronic component having a circuit-forming surface and an adhesive film attached to the circuit-forming surface of the electronic component; step (B) of back-grinding the surface of the electronic component opposite to the circuit-forming surface; and step (C) of irradiating the adhesive film with ultraviolet light and then removing the adhesive film from the electronic component. The adhesive film comprises a base layer and a UV-curable adhesive resin layer provided on one side of the base layer, and the adhesive film after irradiation with ultraviolet light has a 60° peel strength of not less than 0.4 N/25 mm and not more than 5.0 N/25 mm, as measured by the following method.

(method)

The adhesive film was attached to the silicon mirror wafer so that the adhesive resin layer was in contact with the silicon mirror wafer. The adhesive film was then irradiated with UV light at a dominant wavelength of 365 nm and a dose of 1080 mJ/ ^cm² using a high-pressure mercury lamp at an intensity of 100 mW/ ^cm² at 25°C to UV-cure the adhesive resin layer. The adhesive film was then peeled from the silicon mirror wafer along a 60° angle using a tensile testing machine at 23°C and a speed of 150 mm/min. The peel strength (N/25 mm) at this point was defined as the 60° peel strength.

[2]

The method for manufacturing an electronic device as described in [1], wherein the step (A) includes: a step (A1) of at least one selected from a step (A1-1) of half-cutting the electronic component and a step (A1-2) of irradiating the electronic component with a laser to form a modified layer on the electronic component; and a step (A2) of attaching the adhesive film to the circuit-forming surface of the electronic component after step (A1).

[3]

The method for manufacturing an electronic device as described in [1] or [2], wherein in the step (C), the adhesive film is irradiated with ultraviolet rays at a dose of 200 mJ/ ^cm2 or more and 2000 mJ/cm2 or ^less to UV-harden the adhesive resin layer, thereby reducing the adhesive force of the adhesive resin layer, and then the adhesive film is removed from the electronic component.

[4]

The method for manufacturing an electronic device as described in any one of [1] to [3], wherein the adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in its molecule and a photoinitiator.

[5]

The method for manufacturing an electronic device as described in any one of [1] to [4], wherein the thickness of the adhesive resin layer is greater than or equal to 5 μm and less than or equal to 300 μm.

[6]

The method for manufacturing an electronic device as described in any one of [1] to [5], wherein the resin constituting the substrate layer comprises one or more selected from polyolefins, polyesters, polyamides, polyacrylates, polymethacrylates, polyvinyl chloride, polyvinylidene chloride, polyimides, polyetherimides, ethylene-vinyl acetate copolymers, polyacrylonitrile, polycarbonates, polystyrene, ionomers, polysulfones, polyethersulfones, and polyphenylene ethers.

According to the present invention, a method for manufacturing an electronic device can be provided that can suppress adhesive residue on the electronic component side when peeling an adhesive film from the electronic component after the back grinding step.

10: Base material layer

20: Adhesive resin layer

30: Electronic components

30A: Circuit formation surface

50: Adhesive film

100:Structure

Figure 1 is a cross-sectional view schematically showing an example of the structure of an adhesive film according to an embodiment of the present invention.

Figures 2 (A) to (C) are cross-sectional views schematically illustrating an example of a method for manufacturing an electronic device according to an embodiment of the present invention.

The following describes embodiments of the present invention using the drawings. Common reference numerals are used throughout the drawings to designate identical components, and descriptions are omitted where appropriate. The drawings are schematic and do not correspond to actual dimensions. Numerical ranges "A to B" represent values greater than A and less than B unless otherwise specified. In these embodiments, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

FIG1 is a cross-sectional view schematically showing an example of the structure of an adhesive film 50 according to an embodiment of the present invention. FIG2 (A) to (C) are cross-sectional views schematically showing an example of a method for manufacturing an electronic device according to an embodiment of the present invention.

The manufacturing method of the electronic device of the present embodiment comprises at least: step (A) of preparing a structure 100, wherein the structure 100 comprises an electronic component 30 having a circuit forming surface 30A, and an adhesive film 50 attached to the circuit forming surface 30A side of the electronic component 30; step (B) of back grinding the surface of the electronic component 30 opposite to the circuit forming surface 30A side; and step (C) of grinding the adhesive film 50. After irradiating the film 50 with ultraviolet rays, the adhesive film 50 is removed from the electronic component 30. The adhesive film 50 includes a base layer 10 and a UV-curable adhesive resin layer 20 disposed on one side of the base layer 10. The 60° peel strength of the adhesive film 50 after irradiation with ultraviolet rays (after UV curing) measured by the following method is 0.4 N/25 mm or more and 5.0 N/25 mm or less.

(Method) An adhesive film 50 was attached to a silicon mirror wafer so that the adhesive resin layer 20 was in contact with the wafer. The adhesive film 50 was then irradiated with UV light at a dominant wavelength of 365 nm and a dose of 1080 mJ/ ^cm² using a high-pressure mercury lamp at a temperature of 25°C and an intensity of 100 mW/ ^cm² , thereby UV-curing the adhesive resin layer 20. The adhesive film 50 was then peeled from the silicon mirror wafer along a 60° angle using a tensile testing machine at a speed of 150 mm/min and a temperature of 23°C. The peel strength (N/25 mm) at this point was defined as the 60° peel strength.

As described above, the inventors' research has revealed that in electronic device manufacturing processes using methods such as dicing-first or cover-first, adhesive residue is likely to form on the side of the electronic component 30 when the adhesive film 50 is peeled off from the electronic component 30 after the back grinding step.

The reason for this is unclear, but unlike the conventional back grinding step for electronic components 30, this requires peeling the adhesive film 50 from the cut electronic components 30. Therefore, it is believed that adhesive residue is more likely to form at the edges of the cut electronic components 30.

The inventors of the present invention have diligently researched to achieve this goal. As a result, they discovered for the first time that by adjusting the 60° peel strength of the adhesive film 50 after UV irradiation within a specific range, it is possible to suppress adhesive residue on the electronic component 30 side when peeling the adhesive film 50 from the electronic component 30 after the back grinding step.

In the electronic device manufacturing method of this embodiment, from the perspective of preventing adhesive residue on wafers with various surface conditions, the 60° peel strength of the adhesive film 50 after UV irradiation, as measured by the method described above, is 0.4 N/25 mm or greater and 5.0 N/25 mm or less, preferably 3.0 N/25 mm or less, and even more preferably 2.5 N/25 mm or less.

The 60° peel strength of the adhesive film 50 after UV irradiation in step (C) can be controlled within the aforementioned range by, for example, controlling the adhesive resin or crosslinking agent constituting the adhesive resin layer 20, the type or blending ratio of the photoinitiator, and the type or content ratio of each monomer in the adhesive resin.

1. Adhesive film

As shown in FIG1 , the adhesive film 50 of this embodiment includes a base layer 10 and a UV-curable adhesive resin layer 20 disposed on one side of the base layer 10 .

In terms of the balance between mechanical properties and handling, the overall thickness of the adhesive film 50 of this embodiment is preferably 50 μm to 600 μm, more preferably 50 μm to 400 μm, and even more preferably 50 μm to 300 μm.

The adhesive film 50 of this embodiment may also include other layers, such as a bump-absorbing resin layer, an adhesive layer, or an antistatic layer (not shown), between the layers, without impairing the effects of the present invention. The bump-absorbing resin layer can enhance the bump-absorbing properties of the adhesive film 50. The adhesive layer can improve the adhesion between the layers. Furthermore, the antistatic layer can enhance the antistatic properties of the adhesive film 50.

Next, the various layers constituting the adhesive film 50 of this embodiment will be described.

<Base layer>

The base layer 10 is provided to improve the operability, mechanical properties, heat resistance, and other properties of the adhesive film 50.

The base layer 10 is not particularly limited as long as it has mechanical strength sufficient to withstand the external forces applied during processing of the electronic component 30. Examples of such materials include resin films.

Examples of the resin constituting the base layer 10 include one or more selected from the following compounds: 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 poly(m-xylylene adipate); (meth)acrylic resins; polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomers; polysulfone; polyethersulfone; and polyetheretherketone.

Among these, from the perspective of achieving good mechanical properties and transparency, one or more selected from 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.

The base layer 10 may be a single layer or may be composed of two or more layers.

The resin film used to form the base layer 10 can be a stretched film or a film stretched uniaxially or biaxially. From the perspective of improving the mechanical strength of the base layer 10, a film stretched uniaxially or biaxially is preferred. To suppress warping of the electronic component 30 after polishing, it is preferable to pre-anneal the base layer 10. To improve adhesion with other layers, the base layer 10 may also be surface treated. Specifically, treatments such as corona treatment, plasma treatment, undercoat treatment, and primer coating may be performed.

From the perspective of achieving 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.

<Adhesive resin layer>

The adhesive film 50 of this embodiment includes a UV-curable adhesive resin layer 20.

The adhesive resin layer 20 is provided on one side of the base layer 10 and is a layer that contacts and adheres to the circuit forming surface 30A of the electronic component 30 when the adhesive film 50 is attached to the circuit forming surface 30A of the electronic component 30.

Adhesives that constitute the adhesive resin layer 20 include (meth)acrylic adhesives, silicone adhesives, urethane adhesives, olefin adhesives, and styrene adhesives. Among these, (meth)acrylic adhesives based on (meth)acrylic resins are preferred because they allow for easy adjustment of adhesive strength.

In addition, as the adhesive constituting the adhesive resin layer 20, it is preferable to use an ultraviolet crosslinking adhesive whose adhesive strength is reduced by ultraviolet rays.

The adhesive resin layer 20, made of a UV-crosslinking adhesive, undergoes crosslinking upon exposure to UV rays, significantly reducing its adhesive strength. This makes it easier to peel the electronic component 30 from the adhesive film 50.

Examples of the (meth)acrylic resin contained in the (meth)acrylic adhesive 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 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)acrylate compounds may be used alone or in combination.

Examples of comonomers that constitute (meth)acrylic copolymers include vinyl acetate, (meth)acrylonitrile, styrene, (meth)acrylic acid, itaconic acid, (meth)acrylamide, hydroxymethyl(meth)acrylamide, and maleic anhydride. These comonomers may be used alone or in combination.

Examples of UV-crosslinkable (meth)acrylic adhesives include adhesives comprising a (meth)acrylic resin having polymerizable carbon-carbon double bonds in its molecule and a photoinitiator, wherein the (meth)acrylic resin is optionally crosslinked with a crosslinking agent. UV-crosslinkable (meth)acrylic adhesives may further comprise a low-molecular-weight compound having two or more polymerizable carbon-carbon double bonds in its molecule.

Specifically, (meth)acrylic resins containing polymerizable carbon-carbon double bonds in their molecules are obtained as follows. First, a monomer containing an ethylenic double bond is copolymerized with a copolymerizable monomer containing a functional group (P). Next, the functional group (P) contained in the copolymer is reacted with a monomer containing a functional group (Q) capable of undergoing an addition reaction, condensation reaction, or the like with the functional group (P), while the double bonds in the monomer remain, thereby introducing polymerizable carbon-carbon double bonds into the copolymer molecule.

As the monomer having an ethylenic double bond, one or more monomers selected from monomers having an ethylenic double bond such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, butyl (meth)acrylate, and ethyl (meth)acrylate, alkyl acrylate and methacrylate monomers, vinyl esters such as vinyl acetate, (meth)acrylonitrile, (meth)acrylamide, and styrene can be used.

Examples of the copolymerizable monomer having a functional group (P) include (meth)acrylic acid, maleic acid, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, N-hydroxymethyl (meth)acrylamide, and (meth)acryloyloxyethyl isocyanate. These monomers may be used alone or in combination.

The ratio of the monomer having an ethylenic double bond to the copolymerizable monomer having a functional group (P) is preferably 70% to 99% by mass of the monomer having an ethylenic double bond and 1% to 30% by mass of the copolymerizable monomer having a functional group (P). Furthermore, it is more preferred that the monomer having an ethylenic double bond is 80% to 95% by mass and the copolymerizable monomer having a functional group (P) is 5% to 20% by mass.

The monomer having the functional group (Q) can be exemplified by the same monomers as the copolymerizable monomer having the functional group (P).

In a copolymer of a monomer having an ethylenic double bond and a copolymerizable monomer having a functional group (P), the combination of the functional group (P) and the functional group (Q) that reacts upon introduction of a polymerizable carbon-carbon double bond is preferably a combination that readily undergoes an addition reaction, such as a carboxyl group and an epoxy group, a carboxyl group and an aziridine group, or a hydroxyl group and an isocyanate group. Furthermore, the reaction is not limited to an addition reaction; 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, may be used.

Examples of low-molecular-weight compounds having two or more polymerizable carbon-carbon double bonds in the molecule include tripropylene glycol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, tetrahydroxymethylmethane tetraacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and di-trihydroxymethylpropane tetraacrylate. One or more of these compounds can be used. The amount of the low-molecular-weight compound having two or more polymerizable carbon-carbon double bonds added to 100 parts by mass of the (meth)acrylic resin is preferably 0.1 to 20 parts by mass, more preferably 5 to 18 parts by mass.

Examples of photoinitiators include benzoin, isopropylbenzoin ether, isobutylbenzoin ether, benzophenone, Michler's ketone, chlorothioanthrone, dodecylthioanthrone, dimethylthioanthrone, diethylthioanthrone, acetophenone diethyl ketal, benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone, 2,2-dimethoxy-2-phenylacetophenone, and 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)butane-1-one. One or more of these may be used. 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.

A crosslinking agent may also be added to the UV-curable adhesive. 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 tetrahydroxymethylmethane-tris-β-aziridinyl propionate, trihydroxymethylpropane-tris-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 polyisocyanates. The UV-curable adhesive can be any type of solvent, latex, hot melt, etc.

The crosslinking agent content is generally preferably within 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, if new functional groups are generated during the crosslinking reaction or the crosslinking reaction is slow, an excess amount may be added as needed.

From the perspective of improving the heat resistance of the adhesive resin layer 20 and balancing its adhesion, the content of the crosslinking agent in the (meth)acrylic adhesive is preferably 0.1 parts by mass to 15 parts by mass, and more preferably 0.5 parts by mass to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin.

The adhesive resin layer 20 can be formed, for example, by applying an adhesive coating liquid onto the base layer 10.

The adhesive coating liquid can be applied using any of the conventionally known coating methods, such as a roll coater, reverse roll coater, gravure roll coater, rod coater, notch wheel coater, and die coater. Drying conditions for the applied adhesive are not particularly limited, but are generally preferably performed at a temperature between 80°C and 200°C for 10 seconds to 10 minutes. Drying at 80°C to 170°C for 15 seconds to 5 minutes is more preferred. To fully promote the crosslinking reaction between the crosslinking agent and the (meth)acrylic resin, the adhesive coating can be heated at 40°C to 80°C for approximately 5 to 300 hours after drying.

In the adhesive film 50 of this embodiment, the thickness of the adhesive resin layer 20 is preferably 5 μm to 300 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 50 μm. When the thickness of the adhesive resin layer 20 is within this range, a good balance between adhesion to the surface of the electronic component 30 and ease of handling is achieved.

2. Manufacturing method of electronic device

The manufacturing method of the electronic device of this embodiment includes at least the following three steps.

(A) Preparing a structure 100 comprising an electronic component 30 having a circuit-forming surface 30A and an adhesive film 50 attached to the circuit-forming surface 30A side of the electronic component 30; (B) Back-grinding the surface of the electronic component 30 opposite the circuit-forming surface 30A side; and (C) Removing the adhesive film 50 from the electronic component 30 after irradiating the adhesive film 50 with ultraviolet light.

Furthermore, the adhesive film 50 is characterized in that the 60° peel strength after ultraviolet irradiation, as measured by the following method, is greater than or equal to 0.4 N/25 mm and less than or equal to 5.0 N/25 mm.

(Method) An adhesive film 50 was attached to a silicone mirror wafer so that the adhesive resin layer 20 was in contact with the wafer. Next, the adhesive resin layer 20 was irradiated with UV light at a dominant wavelength of 365 nm at a dose of 1080 mJ/ ^cm² using a high-pressure mercury lamp at 25°C and an intensity of 100 mW/ ^cm² , thereby UV-curing the adhesive resin layer 20. The adhesive film 50 was then peeled from the silicone mirror wafer along a 60° angle using a tensile testing machine at 23°C and a speed of 150 mm/min. The peel strength (N/25 mm) at this point was defined as the 60° peel strength.

The following describes each step of the method for manufacturing an electronic device according to this embodiment.

(Step (A))

First, prepare the following structure 100, which includes: an electronic component 30 having a circuit-forming surface 30A; and an adhesive film 50 attached to the circuit-forming surface 30A side of the electronic component 30.

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 forming surface 30A of the electronic component 30 to the adhesive resin layer 20.

The conditions for attaching the circuit-forming surface 30A of the electronic component 30 to the adhesive film 50 are not particularly limited. For example, the temperature can be set to 20°C to 80°C, the pressure can be set to 0.05 MPa to 0.5 MPa, and the attachment speed can be set to 0.5 mm/s to 20 mm/s.

Step (A) preferably further includes: a step (A1) selected from at least one of a step (A1-1) of half-cutting the electronic component 30 and a step (A1-2) of irradiating the electronic component 30 with a laser to form a modified layer on the electronic component 30; and a step (A2) of attaching an adhesive film 50 to the circuit-forming surface 30A of the electronic component 30 after step (A1).

As described above, in electronic device manufacturing processes that utilize a saw-first or blind-first method, electronic components 30 are susceptible to scattering or damage after the back grinding step. Therefore, the electronic device manufacturing method of this embodiment can be suitably applied to electronic device manufacturing processes that utilize a saw-first or blind-first method. Therefore, a manufacturing method that utilizes step (A1-1) of the saw-first method or step (A1-2) of the blind-first method is preferred.

In step (A2), the adhesive film 50 is heated and attached to the circuit-forming surface 30A of the electronic component 30. This maintains a good bond between the adhesive resin layer 20 and the electronic component 30 for a long period of time. The heating temperature is not particularly limited and can be, for example, 60°C to 80°C.

The adhesive film 50 may be attached to the electronic component 30 manually, but is typically done using a device called an automatic laminating machine that is equipped with a roll of adhesive film.

The electronic component 30 attached to the adhesive film 50 is not particularly limited, but preferably has a circuit-forming surface 30A. Examples include semiconductor wafers, epoxy molded wafers, molded panels, molded array packages, and semiconductor substrates. Semiconductor wafers and epoxy molded wafers are 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 tantalum wafers, but silicon wafers are preferably used. Epoxy molded wafers include wafers manufactured using the embedded wafer level ball grid array (EWLB) process, which is one of the fan-out wafer level packaging (WLP) manufacturing methods.

There are no particular restrictions on semiconductor wafers and epoxy molded wafers with circuitry. For example, wafers with circuits such as wiring, capacitors, diodes, or transistors formed on their surfaces can be used. Furthermore, the circuitry surface can also be plasma treated.

The circuit forming surface 30A of the electronic component 30 can be formed into a concave-convex surface by having bump electrodes, for example.

Furthermore, bump electrodes, for example, are used when an electronic device is mounted on a mounting surface. They bond to electrodes formed on the mounting surface and form an electrical connection between the electronic device and the mounting surface (such as a printed circuit board).

Examples of bump electrodes include ball bumps, printed bumps, stud bumps, plated bumps, and pillar bumps. In other words, bump electrodes are typically convex electrodes. These bump electrodes may be used singly or in combination.

There are no specific restrictions on the height and diameter of the bump electrodes, but they are preferably 10μm to 400μm, more preferably 50μm to 300μm. There are also no specific restrictions on the bump pitch, but they are preferably 20μm to 600μm, more preferably 100μm to 500μm.

The metal types used to form the bump electrodes are not particularly limited. Examples 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 types may be used singly or in combination.

(Step (B))

Next, the surface of the electronic component 30 opposite to the circuit forming surface 30A (also referred to as the back surface) is back-ground.

Back grinding here refers to thinning the electronic component 30 to a predetermined thickness without damaging it.

For example, the structure 100 is fixed on a chuck table of a grinding machine, and the back surface (non-circuit-forming surface) of the electronic component 30 is ground.

During this back grinding operation, the electronic component 30 is ground until its thickness reaches or below the desired thickness. The thickness of the electronic component 30 before grinding is appropriately determined based on the diameter and type of the electronic component 30. The thickness of the electronic component 30 after grinding is appropriately determined based on the size of the resulting wafer and the type of circuit.

Alternatively, if the electronic component 30 is half-cut or has a modified layer formed by laser irradiation, the electronic component 30 is singulated in step (B) as shown in FIG1 .

The back grinding method is not particularly limited; any known method can be used. Each type of grinding can be performed while cooling the electronic component 30 and the grinding stone while supplying water. A dry polishing step, which does not use grinding water, can be performed at the end of the grinding process, if necessary. After the back grinding is completed, chemical etching can be performed as needed. Chemical etching is performed using the following methods: immersing the electronic component 30, with the adhesive film 50 attached, in an etching solution selected from the group consisting of acidic aqueous solutions such as hydrofluoric acid, nitric acid, sulfuric acid, and acetic acid, either alone or in mixtures, and alkaline aqueous solutions such as potassium hydroxide and sodium hydroxide solutions, with the adhesive film 50 attached. This etching is performed for the following purposes: removing strain on the back surface of the electronic component 30, further thinning the electronic component 30, removing oxide films, etc., and performing pretreatment for forming electrodes on the back surface. The etching solution is appropriately selected based on the aforementioned purpose.

(Step (C))

Next, after irradiating the adhesive film 50 with ultraviolet rays, the adhesive film 50 is removed from the electronic component 30. In step (C), the adhesive film 50 is irradiated with ultraviolet rays at a dose of, for example, 200 mJ/ ^cm² to 2000 mJ/ ^cm² , thereby UV-curing the adhesive resin layer 20 and reducing the adhesive strength of the adhesive resin layer 20. The adhesive film 50 is then removed from the electronic component 30.

Alternatively, ultraviolet irradiation can be performed using, for example, a high-pressure mercury lamp and ultraviolet light with a main wavelength of 365 nm.

The irradiation intensity of the ultraviolet rays is, for example, 50 mW/cm ² or more and 500 mW/cm ² or less.

Before removing the adhesive film from the electronic component 30 , the electronic component 30 may be mounted on dicing tape or dicing tape with a die attach film. While the adhesive film 50 may be removed manually, it is typically performed using a device known as an automatic stripper.

After the adhesive film 50 is removed, the surface of the electronic component 30 may be cleaned as needed. Examples of cleaning methods include wet cleaning, such as water cleaning and solvent cleaning, and dry cleaning, such as plasma cleaning. Ultrasonic cleaning may also be used in conjunction with wet cleaning. The appropriate cleaning method should be selected based on the degree of contamination on the surface of the electronic component 30.

(Other steps)

After steps (A) to (C) are completed, the obtained semiconductor chip can be mounted on a circuit board. These steps can be performed based on known information.

While preferred embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above may be employed.

[Example]

The present invention is described in detail below using embodiments and comparative examples, but the present invention is not limited thereto.

Details regarding the preparation of the adhesive film are described below.

<Base layer>

Substrate layer 1: Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E7180, thickness: 50μm, single-sided corona treatment)

Substrate layer 2: Laminated film consisting of low-density polyethylene film/polyethylene terephthalate film/low-density polyethylene film (total thickness: 110 μm)

The laminate was obtained by laminating a low-density polyethylene film (density: 0.925 kg/m ³ , thickness: 30 μm) on both sides of a polyethylene terephthalate film (manufactured by Toray Industries, product name: LUMIRROR S10, thickness: 50 μm). One side of the resulting laminate was subjected to a corona treatment.

Substrate layer 3: Laminated film consisting of polyethylene terephthalate film/ethylene-vinyl acetate copolymer film/acrylic film (total thickness: 145 μm)

Polyethylene terephthalate film (Toyobo Co., Ltd., product name: E7180, thickness: 50μm) and ethylene-vinyl acetate copolymer film (Mitsui Dow Polychemical Co., Ltd., MFR: 2.5g/10min) (thickness: 70μm) were laminated by applying a corona treatment to the side of the ethylene-vinyl acetate copolymer film that was bonded to the polyethylene terephthalate film. Furthermore, the side of the ethylene-vinyl acetate copolymer film opposite the polyethylene terephthalate film was also corona treated.

Next, the release surface of the release-treated polyethylene terephthalate film (separator film) was coated with the following acrylic resin coating liquid for the substrate to a dry thickness of 20 μm, dried, and then laminated to the laminated film comprising the polyethylene terephthalate film/ethylene-vinyl acetate copolymer film via an ethylene-vinyl acetate copolymer film and aged (40°C, 3 days). The separator film was then peeled off to obtain substrate layer 3.

<Acrylic resin coating for substrate>

Using 0.5 parts by mass of 4,4'-azobis-4-cyanovaleric acid (ACVA, manufactured by Otsuka Chemical Co., Ltd.) 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 polyoxyethylene nonylpropenylphenyl ether ammonium sulfate (AQUARON HS-1025, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were emulsified and polymerized in deionized water at 70°C for 9 hours. After completion of the polymerization, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous acrylic polymer emulsion with a solids concentration of 42.5%. Next, the pH of the acrylic polymer aqueous emulsion (100 parts by weight) was adjusted to above 9 using aqueous ammonia. 0.75 parts by weight of an aziridine crosslinker (CHEMITITE PZ-33, manufactured by Japan Catalyst Chemical Industry Co., Ltd.) and 5 parts by weight of diethylene glycol monobutyl ether were also added to obtain a coating solution for the substrate.

<(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 of a benzoyl peroxide-based polymerization initiator were reacted in 65 parts by mass of toluene and 50 parts by mass of ethyl acetate at 80°C for 10 hours. After 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. The reaction was continued at 85°C for 32 hours while blowing air into the solution to obtain (meth)acrylic resin solution 1.

(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 in 20 parts by mass of toluene and 80 parts by mass of ethyl acetate at 85°C for 10 hours. After the reaction, the solution was cooled, and 30 parts by mass of toluene, 7 parts by mass of methacryloyloxyethyl isocyanate (KARENZ MOI, manufactured by Showa Denko Ltd.), and 0.05 parts by mass of dibutyltin dilaurate were added. The reaction was continued at 85°C for 12 hours while blowing air into the solution to obtain (meth)acrylic resin solution 2.

(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 acrylate, and 0.8 parts by mass of a benzoyl peroxide-based polymerization initiator were reacted in 7 parts by mass of toluene and 50 parts by mass of ethyl acetate at 80°C for 9 hours. After the reaction, the resulting solution was cooled, and 25 parts by mass of toluene was added to the cooled solution to obtain (meth)acrylic resin solution 3.

<Adhesive Film Preparation>

An adhesive coating liquid for the adhesive resin layer was prepared by adding the additives listed in Table 1 to an acrylic resin solution. This coating liquid was applied to a silicone release-treated polyethylene terephthalate film (separator film). The film was then dried at 120°C for 3 minutes to form a 20μm thick adhesive resin layer, which was then laminated to the substrate layers. Substrate layers 1 and 2 were laminated to the corona-treated surface. Substrate layer 3 was laminated to the acrylic layer side after removing the separator film. The resulting laminate was heated in an oven at 40°C for 3 days to produce an adhesive film.

<Adhesive Film Evaluation Method>

(1) 60° peel strength after UV curing

A silicon mirror wafer (8-inch single-sided mirror wafer) was cut into 50mm x 100mm pieces. The wafer mirror surface was ozone cleaned using an ultraviolet (UV) ozone cleaning system (Technovision UV-208) (ozone treatment time: 60 seconds). The wafer mirror surface was then wiped with ethanol, and the resulting wafer was used as the bonded wafer.

In an environment of 23°C and 50% RH, the adhesive film was cut into 25mm wide strips. The separator film was then removed and the film was applied to the mirror surface of the substrate wafer using a manual roller through its adhesive resin layer. The film was then left to stand for one hour. After this period, the film was irradiated with UV light at ^a dominant wavelength of 365nm and a dose of 1080mJ/ ^cm² using a high-pressure mercury lamp at an intensity of 100mW/cm². The substrate wafer with the adhesive film attached was then mounted on an adhesive/film peeling analyzer (VPA-2S, manufactured by Kyowa Interface Science Co., Ltd.), and one end of the adhesive film was secured to the side of the pressure sensor using transparent tape. The adhesive film was peeled from the surface of the wafer at a peeling angle of 60° and a peeling speed of 150 mm/min. The 60° peel strength after UV irradiation was calculated based on the stress at that time. The evaluation was performed with N = 2, and the average of the values was used as the measured value.

(2) 180° peel strength evaluation

Bonded wafer:

The mirror surface of a silicon mirror wafer (4-inch single-sided mirror wafer) was ozone cleaned using a UV ozone cleaning device (Technovision UV-208) (ozone treatment time: 60 seconds). The mirror surface was then wiped with ethanol, and the resulting wafer was used as the bonded wafer.

Peeling intensity before UV irradiation:

Under conditions of 23°C and 50% RH, the adhesive film was cut into 50mm wide sections. The separator film was removed and the film was attached to the surface of the substrate wafer using a manual roller through its adhesive resin layer. The film was then left for one hour. After this period, a tensile tester (Shimadzu Corporation, Autograph AGS-X) was used to clamp one end of the film and peel it from the substrate wafer surface at a peeling angle of 180 degrees and a peeling speed of 300 mm/min. The stress at this point was measured and converted to N/25 mm to determine the peel strength. Evaluations were performed using a tester with N=2, and the average of the values was used as the measured value.

Peel strength after UV irradiation: At 23°C and 50% RH, the adhesive film was cut into 50mm wide sections. The separator film was removed and the adhesive film was attached to the wafer mirror surface via its adhesive resin layer using a manual roller. The film was then left for one hour. After this time, the adhesive film was irradiated with 1080mJ/ ^cm² of UV light at a dominant wavelength of 365nm using a high-pressure mercury lamp at an intensity of 100mW/ ^cm² at 25°C. Next, using a tensile testing machine (Shimadzu Corporation, Autograph AGS-X), one end of the adhesive film was clamped and peeled from the surface of the wafer at a peeling angle of 180 degrees and a peeling speed of 300 mm/min. The stress at this point was measured and converted to N/25 mm to determine the peel strength. Evaluations were performed using N=2, and the average of the values was used as the measured value.

Residual rubber evaluation:

The peeled wafers were visually inspected and evaluated according to the following criteria.

○ (Good): No residual rubber was found.

×(Poor): Residual rubber was detected

(3) First Cut Evaluation

Evaluation Wafer 1:

Evaluation wafer 1 was obtained by half-cutting the mirror surface of an 8-inch mirror wafer (diameter: 200 ± 0.5 mm, thickness: 725 ± 50 μm, single-sided mirror) using a dicing saw (blade: ZH05-SD3500-N1-70-DD, wafer size: 5 mm × 8 mm, kerf depth: 58 μm, blade rotation speed: 30,000 rpm). Inspection of evaluation wafer 1 under an optical microscope revealed a scribe width of 35 μm.

Evaluation Chip 2:

A first-stage half-cut was performed on the mirror surface of an 8-inch mirror wafer (diameter: 200±0.5mm, thickness: 725±50μm, single-sided mirror) using a dicing saw (blade: Z09-SD2000-Y1 58×0.25A×40×45E-L, wafer size: 5mm×8mm, kerf depth: 15μm, blade rotation speed: 30,000rpm). Observation under an optical microscope revealed a scribe width of 60μm. Subsequently, a second half-cut was performed (blade: ZH05-SD3500-N1-70-DD, wafer size: 5mm×8mm, kerf depth: 58μm, blade rotation speed: 30,000rpm), resulting in evaluation wafer 2.

Cutting method first:

An adhesive film was attached to the half-cut surface of the evaluation wafer using a tape laminating machine (DR3000II, manufactured by Nitto Denko Corporation) (23°C, attachment speed: 5 mm/min, attachment pressure: 0.36 MPa).

Next, the wafer was back-ground using a grinder (DISCO DGP8760) (rough grinding and precision grinding, precision grinding depth: 40 μm, no polishing, thickness after grinding: 38 μm) and singulated.

Regarding chip scattering during pre-dicing, after back grinding, it was evaluated visually based on the following criteria.

○ (Good): No chip flying was observed, including at the triangular corners.

× (Poor): Chip scattering was observed, including at the triangular corners.

Then, UV irradiation and adhesive film peeling were performed to evaluate the residual adhesive after the cutting method.

UV irradiation was performed using a high-pressure mercury lamp at a temperature of 25°C and an intensity of 100 mW/ ^cm2 to irradiate the adhesive film with UV radiation of 365 nm at a dominant wavelength of 365 nm and a dose of 1080 mJ/ ^cm2 .

The adhesive film was peeled off according to the following procedure. First, using a wafer mounter (Nitto Denko Corporation, MSA300), a separately prepared dicing tape (used as mounting tape) was attached to an 8-inch wafer ring frame and the wafer sides of the singulated wafers via the adhesive surface of the dicing tape. Next, using a tape peeler (Nitto Denko Corporation, HR3000III), the adhesive film was peeled off from the wafer cutouts using peeling tape (Lasting Systems, PET38REL). The device's releasability was evaluated according to the following criteria.

○ (Good): The adhesive film can be peeled off from the wafer for the first time.

× (Poor): The adhesive film cannot be peeled off from the wafer on the first try.

The residual adhesive on the singulated wafers after the dicing process was evaluated using an optical microscope (manufactured by Olympus) according to the following criteria.

○ (Good): No residual rubber was found.

×(Poor): Residual rubber was detected

[Example 1]

To 100 parts by weight of (meth)acrylic resin solution 1 (solid content), 6.9 parts by weight of 2,2-dimethoxy-2-phenylacetophenone (OMNIRAD 651, manufactured by IGM) and 0.93 parts by weight of an isocyanate crosslinker (OLESTER P49-75S, manufactured by Mitsui Chemicals) were added to obtain adhesive coating solution 1 for the adhesive resin layer. An adhesive film was prepared using the above method. Furthermore, after UV curing, 60° peel strength, 180° peel strength, and pre-cutting evaluations were conducted based on the evaluation methods described above. The results are shown in Table 1.

[Examples 2 to 9 and Comparative Examples 1 and 2]

Adhesive films were prepared in the same manner as in Example 1, except that the types of adhesive resin layer and base material layer were changed to those shown in Table 1. Furthermore, each evaluation was performed in the same manner as in Example 1. The obtained results are shown in Table 1.

The compounds listed in Table 1 are as follows.

OMNIRAD 651 (manufactured by IGM): 2,2-dimethoxy-2-phenylacetophenone

OMNIRAD 369 (manufactured by IGM): 2-Benzyl-2-dimethylamino-4'-morpholinobutyrophenone

ARONIX M400 (manufactured by Toagosei Co., Ltd.): A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

NK Ester AD-TMP (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): Di-trihydroxymethylpropane tetraacrylate

This application claims priority based on Japanese application No. 2020-125478, filed on July 22, 2020, and incorporates the entire disclosure of that application into this application.

10: Base material layer

20: Adhesive resin layer

30: Electronic components

30A: Circuit formation surface

50: Adhesive film

100:Structure

Claims (6)

A method for manufacturing an electronic device comprises at least: step (A) of preparing a structure comprising an electronic component having a circuit-forming surface and an adhesive film attached to the circuit-forming surface side of the electronic component; step (B) of back-grinding a surface of the electronic component opposite to the circuit-forming surface side; and step (C) of removing the adhesive film from the electronic component after irradiating the adhesive film with ultraviolet light, wherein the adhesive film comprises a base layer and a UV-curable adhesive resin layer provided on one side of the base layer; and the 60° peel strength of the adhesive film after irradiation with ultraviolet light, as measured by the following method, is 0.4 N/25 mm or more and 5.0 N/25 mm or less. (Method) The adhesive film was attached to the silicon mirror wafer so that the adhesive resin layer was in contact with the silicon mirror wafer. The adhesive film was then irradiated with UV light at a dominant wavelength of 365 nm and a dose of 1080 mJ/ ^cm² using a high-pressure mercury lamp at an intensity of 100 mW/ ^cm² at 25°C to UV-harden the adhesive resin layer. The adhesive film was then peeled from the silicon mirror wafer along a 60° angle using a tensile testing machine at a speed of 150 mm/min at 23°C. The peel strength (N/25 mm) at this point was defined as the 60° peel strength. The method for manufacturing an electronic device as described in claim 1, wherein the step (A) comprises: a step (A1) selected from at least one of a step (A1-1) of half-cutting the electronic component and a step (A1-2) of irradiating the electronic component with a laser to form a modified layer on the electronic component; and a step (A2) of attaching the adhesive film to the circuit-forming surface of the electronic component after step (A1). The method for manufacturing an electronic device according to claim 1 or claim 2, wherein, in the step (C), the adhesive film is irradiated with ultraviolet rays at a dose of 200 mJ/ ^cm2 or more and 2000 mJ/ ^cm2 or less to UV-cure the adhesive resin layer, thereby reducing the adhesive force of the adhesive resin layer, and then the adhesive film is removed from the electronic component. The method for manufacturing an electronic device as described in claim 1 or claim 2, wherein the adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in its molecule and a photoinitiator. The method for manufacturing an electronic device according to claim 1 or claim 2, wherein the thickness of the adhesive resin layer is not less than 5 μm and not more than 300 μm. The method for manufacturing an electronic device according to claim 1 or claim 2, wherein the resin constituting the substrate layer comprises one or more selected from the group consisting of polyolefins, polyesters, polyamides, polyacrylates, polymethacrylates, polyvinyl chloride, polyvinylidene chloride, polyimides, polyetherimides, ethylene-vinyl acetate copolymers, polyacrylonitrile, polycarbonates, polystyrenes, ionomers, polysulfones, polyethersulfones, and polyphenylene ethers.