JP7556964B2 - Manufacturing method of electronic device - Google Patents

Description

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

2. Description of the Related Art In the process of manufacturing electronic devices, in the step of grinding electronic components, an adhesive film is attached to the circuit-forming surface of the electronic components in order to fix the electronic components and prevent damage to the electronic components.
Such adhesive films generally comprise a base film and an adhesive resin layer laminated thereon.

2. Description of the Related Art With the advancement of high density mounting technology, there is a demand for thinner electronic components such as semiconductor wafers. For example, there is a demand for thinning down to a thickness of 50 μm or less.
As one of such thinning processes, there is a pre-dicing method in which a groove of a predetermined depth is formed on the surface of an electronic component before grinding the electronic component, and then the electronic component is divided into individual parts by grinding. There is also a pre-stealth method in which a laser is irradiated inside the electronic component before grinding to form a modified region, and then the electronic component is divided into individual parts by grinding.

Technologies relating to adhesive films for such dicing-first and stealth-first methods include, for example, those described in Patent Document 1 (JP 2014-75560 A) and Patent Document 2 (JP 2016-72546 A).

Patent Document 1 describes a surface protection sheet having a pressure-sensitive adhesive layer on a substrate, which satisfies the following requirements (a) to (d).
(a) the Young's modulus of the substrate is 450 MPa or more; (b) the storage modulus of the adhesive layer at 25°C is 0.10 MPa or more; (c) the storage 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 prevent contamination of the protected surface of the workpiece by suppressing the infiltration of water (sludge infiltration) into the protected surface of the workpiece through the gap formed when the workpiece is broken during the back grinding process of the workpiece.

Patent Document 2 describes an adhesive tape for protecting the surface of a semiconductor wafer, which comprises a base resin film and a radiation-curable adhesive layer formed on at least one side of the base resin film, the base resin film having at least one rigid layer having a tensile modulus of elasticity of 1 to 10 GPa, and the adhesive layer having a peel force of 0.1 to 3.0 N/25 mm at a peel angle of 30° after being radiation-cured.
Patent Document 2 describes that such an adhesive tape for protecting the surface of a semiconductor wafer suppresses kerf shift of individualized semiconductor chips during the back grinding process of a semiconductor wafer using a first dicing method or a first stealth method, and enables the semiconductor wafer to be processed without being damaged or contaminated.

JP 2014-75560 A JP 2016-72546 A

According to the research of the present inventors, it has become clear that in the manufacturing process of electronic devices using, for example, a dicing-first method or a stealth-first method, when peeling an adhesive film from an electronic component after the backgrinding process, adhesive residue is likely to remain on the electronic component.

The present invention has been made in consideration of the above circumstances, and provides a manufacturing method for electronic devices that can suppress adhesive residue on the electronic components when peeling off the adhesive film from the electronic components after the backgrinding process.

The present inventors conducted extensive research to achieve the above object. As a result, they discovered that by adjusting the 60° peel strength of the adhesive film after ultraviolet irradiation to a specific range, it is possible to suppress adhesive residue on the electronic component when peeling the adhesive film from the electronic component after the backgrinding process, and thus completed the present invention.

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

[1]
A step (A) of preparing a structure including an electronic component having a circuit formation surface and an adhesive film attached to the circuit formation surface side of the electronic component;
A step (B) of backgrinding a surface of the electronic component opposite to the circuit formation surface;
(C) a step of removing the adhesive film from the electronic component after irradiating the adhesive film with ultraviolet light;
A method for manufacturing an electronic device comprising at least
The adhesive film comprises a base layer and an ultraviolet-curable adhesive resin layer provided on one surface side of the base layer,
A method for producing an electronic device, wherein in the step (C), the 60° peel strength of the pressure-sensitive adhesive film after irradiation with ultraviolet light, as measured by the following method, is 0.4 N/25 mm or less and 5.0 N/25 mm or less.
(method)
Using a tensile tester, the adhesive film after ultraviolet irradiation is peeled from the electronic component in a 60° direction at 23°C and a speed of 150 mm/min, and the strength (N/25 mm) at this point is defined as the 60° peel strength.
[2]
In the method for producing an electronic device according to the above-mentioned [1],
The above step (A)
At least one step (A1) 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;
After the step (A1), a step (A2) of attaching the adhesive film to the circuit-forming surface of the electronic component;
A method for manufacturing an electronic device comprising the steps of:
[3]
In the method for producing an electronic device according to the above [1] or [2],
In the step (C), the adhesive film is irradiated with ultraviolet light at a dose of 200 mJ/ ^cm2 or more and 2000 mJ/cm2 or ^less to cure the adhesive resin layer with ultraviolet light, thereby reducing the adhesive strength of the adhesive resin layer, and then the adhesive film is removed from the electronic component.
[4]
In the method for manufacturing an electronic device according to any one of the above items [1] to [3],
The adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule, and a photoinitiator.
[5]
In the method for manufacturing an electronic device according to any one of the above items [1] to [4],
The method for producing an electronic device, wherein the adhesive resin layer has a thickness of 5 μm or more and 300 μm or less.
[6]
In the method for manufacturing an electronic device according to any one of the above items [1] to [5],
A method for manufacturing an electronic device, wherein the resin constituting the base layer contains one or more selected from polyolefin, polyester, polyamide, polyacrylate, polymethacrylate, polyvinyl chloride, polyvinylidene chloride, polyimide, polyetherimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, polysulfone, polyethersulfone and polyphenylene ether.

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

1 is a cross-sectional view showing a schematic example of a structure of an adhesive film according to an embodiment of the present invention. 1A to 1C are cross-sectional views illustrating an example of a method for manufacturing an electronic device according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all drawings, similar components are given the same reference numerals and the description will be omitted as appropriate. The drawings are schematic and do not correspond to the actual dimensional ratios. The numerical range "A to B" indicates A or more and B or less unless otherwise specified. In this embodiment, "(meth)acrylic" means acrylic, methacrylic, or both acrylic and methacrylic.

Fig. 1 is a cross-sectional view showing an example of the structure of an adhesive film 50 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing an example of a method for manufacturing an electronic device according to an embodiment of the present invention.
The method for manufacturing an electronic device according to the present embodiment includes at least a step (A) of preparing a structure 100 including an electronic component 30 having a circuit formation surface 30A and an adhesive film 50 bonded to the circuit formation surface 30A side of the electronic component 30, a step (B) of backgrinding the surface of the electronic component 30 opposite the circuit formation surface 30A side, and a step (C) of removing the adhesive film 50 from the electronic component 30 after irradiating the adhesive film 50 with ultraviolet light, in which the adhesive film 50 includes a base layer 10 and an ultraviolet-curable adhesive resin layer 20 provided on one side of the base layer 10, and in the step (C), the 60° peel strength of the adhesive film 50 after irradiation with ultraviolet light (after ultraviolet curing), measured by the following method, is 0.4 N/25 mm or more and 5.0 N/25 mm or less.
(Method) Using a tensile tester, the adhesive film 50 after ultraviolet irradiation is peeled from the electronic component 30 in a 60° direction under conditions of 23°C and a speed of 150 mm/min, and the strength (N/25 mm) at this point is defined as the 60° peel strength.

As described above, according to the research of the present inventors, it has become clear that in the manufacturing process of electronic devices using, for example, a dicing-first method or a stealth-first method, when peeling the adhesive film 50 from the electronic component 30 after the backgrinding process, adhesive residue is likely to remain on the electronic component 30.
The reason for this is not clear, but it is thought that, unlike a normal backgrinding process for electronic components 30, it is necessary to peel off the adhesive film 50 from the cut electronic components 30, which makes it more likely that glue residue will remain on the edges of the cut electronic components 30.
The present inventors have conducted extensive research to achieve the above object, and as a result, have found for the first time that by adjusting the 60° peel strength of the adhesive film 50 after irradiation with ultraviolet light to 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 backgrinding process.

In the manufacturing method for an electronic device according to this embodiment, the 60° peel strength of the adhesive film 50 after irradiation with ultraviolet light in step (C) is adjusted to 0.4 N/25 mm or more and 5.0 N/25 mm or less, preferably 3.0 N/25 mm or less, and more preferably 2.5 N/25 mm or less, from the viewpoint of preventing adhesive residue on electronic components 30 having various surface conditions.
The 60° peel strength of the adhesive film 50 after irradiation with ultraviolet light in step (C) can be controlled within the above range, for example, by controlling the types and blending ratios of the adhesive resin, crosslinking agent, and photoinitiator that constitute the adhesive resin layer 20, the types and content ratios of each monomer in the adhesive resin, and the ultraviolet light irradiation conditions in step (C) (e.g., ultraviolet light amount, irradiation intensity, irradiation time).

1. Adhesive Film As shown in Fig. 1, an adhesive film 50 according to this embodiment includes a base layer 10 and an ultraviolet-curable adhesive resin layer 20 provided on one surface of the base layer 10.

The overall thickness of the adhesive film 50 in this embodiment is preferably 50 μm or more and 600 μm or less, more preferably 50 μm or more and 400 μm or less, and even more preferably 50 μm or more and 300 μm or less, in terms of the balance between mechanical properties and handleability.

The adhesive film 50 according to this embodiment may have other layers between each layer, such as an unevenness-absorbing resin layer, an adhesive layer, or an antistatic layer (not shown), as long as the effects of the present invention are not impaired. The unevenness-absorbing resin layer can improve the unevenness absorption of the adhesive film 50. The adhesive layer can improve the adhesion between each layer. Furthermore, the antistatic layer can improve the antistatic properties of the adhesive film 50.

Next, we will explain each layer that constitutes the adhesive film 50 in this embodiment.

<Base layer>
The base layer 10 is a layer provided for the purpose of improving the properties of the pressure-sensitive adhesive film 50, such as ease of handling, mechanical properties, and heat resistance.
The base layer 10 is not particularly limited as long as it has a mechanical strength sufficient to withstand the external force applied when processing the electronic component 30, and may be, for example, a resin film.
Examples of the resin constituting the base layer 10 include one or more selected from polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly(1-butene); polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6, nylon-66, and polymetaxylene adipamide; (meth)acrylic resins; polyvinyl chloride; polyvinylidene chloride; polyimide; polyetherimide; ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomer; polysulfone; polyethersulfone; and polyetheretherketone.
Among these, from the viewpoint of improving 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 substrate layer 10 may be a single layer or two or more layers.
The resin film used to form the base layer 10 may be in the form of a stretched film or a film stretched in a uniaxial or biaxial direction, but from the viewpoint of improving the mechanical strength of the base layer 10, a film stretched in a uniaxial or biaxial direction is preferable. The base layer 10 is preferably annealed in advance from the viewpoint of suppressing warping of the electronic component 30 after grinding. The base layer 10 may be surface-treated to improve adhesion to other layers. Specifically, corona treatment, plasma treatment, undercoat treatment, primer coat treatment, etc. may be performed.

From the viewpoint of obtaining good film characteristics, 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 according to this embodiment includes an ultraviolet-curing adhesive resin layer 20 .
The adhesive resin layer 20 is a layer provided on one side of the base layer 10, and is a layer that comes into contact with and adheres to the circuit formation surface 30A of the electronic component 30 when the adhesive film 50 is attached to the circuit formation surface 30A of the electronic component 30.

Examples of adhesives constituting the adhesive resin layer 20 include (meth)acrylic adhesives, silicone adhesives, urethane adhesives, olefin adhesives, and styrene adhesives. Among these, (meth)acrylic adhesives that use (meth)acrylic resins as the base polymer are preferred because they allow easy adjustment of the adhesive strength.

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 light.
The adhesive resin layer 20 made of an ultraviolet-crosslinking adhesive agent is crosslinked by irradiation with ultraviolet light, and the adhesive strength is significantly reduced, so that the electronic component 30 can be easily peeled off from the adhesive film 50 .

Examples of the (meth)acrylic resin contained in the (meth)acrylic pressure-sensitive adhesive include a homopolymer of a (meth)acrylic acid ester compound, a copolymer of a (meth)acrylic acid ester compound and a comonomer, etc. Examples of the (meth)acrylic acid ester compound 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)acrylic acid ester compounds may be used alone or in combination of two or more.
Examples of comonomers constituting the (meth)acrylic copolymer include vinyl acetate, (meth)acrylonitrile, styrene, (meth)acrylic acid, itaconic acid, (meth)acrylamide, methylol (meth)acrylamide, maleic anhydride, etc. These comonomers may be used alone or in combination of two or more.

An example of an ultraviolet-crosslinking (meth)acrylic adhesive is an adhesive containing a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule and a photoinitiator, and optionally obtained by crosslinking the (meth)acrylic resin with a crosslinking agent. The ultraviolet-crosslinking (meth)acrylic adhesive may further contain a low molecular weight compound having two or more polymerizable carbon-carbon double bonds in the molecule.

Specifically, a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule is obtained as follows. First, a monomer having an ethylenic double bond is copolymerized with a copolymerizable monomer having a functional group (P). Next, the functional group (P) contained in this copolymer is reacted with a monomer having a functional group (Q) that can undergo an addition reaction, condensation reaction, or the like with the functional group (P) while leaving the double bond in the monomer, thereby introducing a polymerizable carbon-carbon double bond into the copolymer molecule.

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

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, etc. These may be used alone or in combination of two or more.
The ratio of the monomer having an ethylenic double bond to the copolymerizable monomer having a functional group (P) is preferably 70 to 99% 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), and more preferably 80 to 95% by mass of the monomer having an ethylenic double bond and 5 to 20% by mass of the copolymerizable monomer having a functional group (P).
Examples of the monomer having the functional group (Q) include the same monomers as the copolymerizable monomer having the functional group (P).

When introducing a polymerizable carbon-carbon double bond into a copolymer of a monomer having an ethylenic double bond and a copolymerizable monomer having a functional group (P), the combination of functional group (P) and functional group (Q) to be reacted is preferably a combination that easily undergoes an addition reaction, such as a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, or a hydroxyl group and an isocyanate group. In addition to addition reactions, any reaction that easily introduces a polymerizable carbon-carbon double bond may be used, such as a condensation reaction between a carboxylic acid group and a hydroxyl group.

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

Examples of photoinitiators include benzoin, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecyl thioxanthone, dimethyl thioxanthone, diethyl thioxanthone, 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. These may be used alone or in combination. 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 be added to the ultraviolet curing 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 tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide); and isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, and polyisocyanate. The ultraviolet curing adhesive may be of any of the following types: solvent type, emulsion type, and hot melt type.

The content of the crosslinking agent is usually preferably in a range in which the number of functional groups in the crosslinking agent is not greater than the number of functional groups in the (meth)acrylic resin, but may be excessively contained as necessary when new functional groups are generated by the crosslinking reaction or when the crosslinking reaction is slow.
From the viewpoint of improving the balance between the heat resistance and adhesion of the adhesive resin layer 20, the content of the crosslinking agent in the (meth)acrylic adhesive is preferably 0.1 parts by mass or more and 15 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less, relative to 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 .
As a method for applying the adhesive coating liquid, for example, a conventionally known coating method 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 of the applied adhesive are not particularly limited, but it is generally preferable to dry at a temperature range of 80 to 200°C for 10 seconds to 10 minutes. More preferably, it is dried 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 liquid is completed, it may be heated at 40 to 80°C for about 5 to 300 hours.

In the adhesive film 50 according to this embodiment, 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. When the thickness of the adhesive resin layer 20 is within the above range, a good balance is achieved between adhesion to the surface of the electronic component 30 and ease of handling.

2. Method for Manufacturing an Electronic Device 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 an electronic component 30 having a circuit formation surface 30A and an adhesive film 50 attached to the circuit formation surface 30A side of the electronic component 30; (B) a step of backgrinding the surface of the electronic component 30 opposite the circuit formation surface 30A side; and (C) a step of irradiating the adhesive film 50 with ultraviolet light and then removing the adhesive film 50 from the electronic component 30. The process is characterized in that in step (C), the 60° peel strength of the adhesive film 50 after irradiation with ultraviolet light is 0.4 N/25 mm or more and 5.0 N/25 mm or less.
Each step of the method for manufacturing an electronic device according to this embodiment will be described below.

(Step (A))
First, a structure 100 including 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 is prepared.
Such a structure 100 can be produced, for example, by peeling off 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 attaching the circuit formation surface 30A of the electronic component 30 onto the adhesive resin layer 20.

Here, the conditions for attaching the circuit formation surface 30A of the electronic component 30 to the adhesive film 50 are not particularly limited, but for example, the temperature can be 20 to 80°C, the pressure can be 0.05 to 0.5 MPa, and the attachment speed can be 0.5 to 20 mm/sec.

It is preferable that the step (A) further includes at least one step (A1) selected from 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 formation surface 30A side of the electronic component 30 after the step (A1).
As described above, in the manufacturing process of electronic devices using a dicing-first method, a stealth-first method, etc., flying or chipping of the electronic components 30 is likely to occur after the back grinding step, so the manufacturing method of the electronic device according to this embodiment can be suitably applied to the manufacturing process of electronic devices using a dicing-first method, a stealth-first method, etc. Therefore, a manufacturing method that performs the above-mentioned step (A1-1) which is a dicing-first method and the above-mentioned step (A1-2) which is a stealth-first method is preferable.

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

The operation of attaching the adhesive film 50 to the electronic component 30 may be performed manually, but is generally performed by a device called an automatic application machine that is equipped with a roll of adhesive film.

The electronic component 30 to be attached to the adhesive film 50 is not particularly limited, but is preferably an electronic component 30 having a circuit formation surface 30A. Examples of the electronic component 30 include a semiconductor wafer, an epoxy molded wafer, a molded panel, a molded array package, a semiconductor substrate, and the like, and the semiconductor wafer and the epoxy molded wafer are preferred.
Examples of the semiconductor wafer include silicon wafers, sapphire wafers, germanium wafers, germanium-arsenic wafers, gallium-phosphorus wafers, gallium-arsenic-aluminum wafers, gallium-arsenic wafers, and lithium tantalate wafers, but the silicon wafer is preferably used. Examples of the epoxy mold wafer include wafers manufactured by the eWLB (Embedded Wafer Level Ball Grid Array) process, which is one of the manufacturing methods for fan-out type WLP.
The semiconductor wafer and epoxy mold wafer having a circuit-forming surface are not particularly limited, but for example, the wafer may have circuits such as wiring, capacitors, diodes, transistors, etc. formed on the surface. The circuit-forming surface may be plasma-treated.

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

(Step (B))
Next, the surface of the electronic component 30 opposite the circuit formation surface 30A (also called the back surface) is back-ground.
Here, back grinding means thinning the electronic component 30 to a predetermined thickness without damaging the electronic component 30 .
For example, the structure 100 is fixed to a chuck table or the like of a grinding machine, and the back surface (the surface on which no circuit is formed) of the electronic component 30 is ground.

In such a back grinding operation, the electronic component 30 is ground until the thickness becomes equal to or less than a desired thickness. The thickness of the electronic component 30 before grinding is appropriately determined depending on the diameter, type, etc. of the electronic component 30, and the thickness of the electronic component 30 after grinding is appropriately determined depending on the size of the obtained chip, type of circuit, etc.
Furthermore, when the electronic component 30 is half-cut or a modified layer is formed by laser irradiation, the electronic component 30 is divided into individual components by step (B) as shown in FIG.

The back grinding method is not particularly limited, but a known grinding method can be adopted. Each grinding can be performed while cooling the electronic component 30 and the grindstone by pouring water over them. If necessary, a dry polishing process, which is a grinding method that does not use grinding water, can be performed at the end of the grinding process. After the back grinding is completed, chemical etching is performed as necessary. Chemical etching is performed by immersing the electronic component 30 with the adhesive film 50 attached in an etching solution selected from the group consisting of an acidic aqueous solution consisting of a single or mixed solution of hydrofluoric acid, nitric acid, sulfuric acid, acetic acid, etc., an alkaline aqueous solution such as an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, etc. The etching is performed for the purpose of removing distortion generated on the back surface of the electronic component 30, further thinning the electronic component 30, removing oxide films, etc., and pretreatment when forming an electrode on the back surface. The etching solution is appropriately selected according to the above purpose.

(Step (C))
Next, the adhesive film 50 is irradiated with ultraviolet rays, and then the adhesive film 50 is removed from the electronic component 30. In the step (C), the adhesive film 50 is irradiated with ultraviolet rays at a dose of, for example, 200 mJ/ ^cm2 or more and 2000 mJ/cm2 or ^less to cure the adhesive resin layer 20 with ultraviolet rays, thereby reducing the adhesive force of the adhesive resin layer 20, and then the adhesive film 50 is removed from the electronic component 30.
The ultraviolet irradiation can be performed, for example, by using ultraviolet rays having a dominant wavelength of 365 nm from a high-pressure mercury lamp.
The irradiation intensity of the ultraviolet light is, for example, not less than 50 mW/cm ² and not more than 500 mW/cm ² .

Before removing the adhesive film from the electronic component 30, the electronic component 30 may be mounted on a dicing tape or a dicing tape with a die attach film. The operation of removing the adhesive film 50 from the electronic component 30 may be performed manually, but can generally be performed by a device called an automatic peeling machine.
The surface of the electronic component 30 after peeling off the adhesive film 50 may be washed as necessary. Examples of the washing method include wet washing such as water washing or solvent washing, and dry washing such as plasma washing. In the case of wet washing, ultrasonic washing may be used in combination. These washing methods can be appropriately selected depending on the contamination state of the surface of the electronic component 30.

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

The above describes preferred embodiments of the present invention, but these are merely examples of the present invention and various configurations other than those described above can also be adopted.

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited thereto.
Details regarding the preparation of the adhesive film are as follows.

<Base layer>
Base layer 1: Polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., product name: E7180, thickness: 50 μm, one side corona treated)

Base layer 2: Laminated film consisting of low-density polyethylene film/polyethylene terephthalate film/low-density polyethylene film (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). One side of the resulting laminated film was subjected to a corona treatment.

Base layer 3: Polyethylene terephthalate film/ethylene-vinyl acetate copolymer film/acrylic film laminated film (total thickness: 145 μm)
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 Polychemicals Co., Ltd., MFR: 2.5 g/10 min) film (thickness: 70 μm) were laminated by subjecting the bonding surface of the ethylene-vinyl acetate copolymer film to a corona discharge treatment. Furthermore, the opposite surface of the ethylene-vinyl acetate copolymer film to the polyethylene terephthalate film was also subjected to a corona discharge treatment.
Next, the release surface of the release-treated polyethylene terephthalate film (separator) was coated with the following acrylic resin coating solution for substrates to a dry thickness of 20 μm, dried, and then bonded to the laminate film consisting of the above-mentioned polyethylene terephthalate film/ethylene-vinyl acetate copolymer film via the ethylene-vinyl acetate copolymer film, and aged (40° C., 3 days). Next, the separator was peeled off to obtain a substrate layer 3.

<Acrylic resin coating liquid for substrate>
Using 0.5 parts by mass of 4,4'-azobis-4-cyanovaleric acid (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 polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) were emulsion-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, 100 parts by mass of this acrylic polymer aqueous emulsion was adjusted to pH 9 or more using ammonia water, and 0.75 parts by mass of an aziridine-based crosslinking agent [ChemiTite PZ-33, manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.] and 5 parts by mass of diethylene glycol monobutyl ether were added to obtain a coating liquid for substrates.

<(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 as a 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 completion of the reaction, the resulting solution was cooled, and 25 parts by mass of xylene, 5 parts by mass of acrylic acid, and 0.5 parts by mass of tetradecyldimethylbenzylammonium chloride were added to the cooled solution, and the mixture was reacted at 85° C. for 32 hours while blowing in air, 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-butylperoxy-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 was completed, the 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 in air, 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 methacrylate, and 0.8 parts by mass of a benzoyl peroxide-based polymerization initiator as a 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 completion of the reaction, the resulting solution was cooled, and 25 parts by mass of toluene was added to the cooled solution, thereby obtaining (meth)acrylic resin solution 3.

<Preparation of adhesive film>
The additives shown in Table 1 were added to the acrylic resin solution to prepare an adhesive coating solution for the adhesive resin layer. This coating solution was applied to a polyethylene terephthalate film (separator) that had been subjected to a silicone release treatment. Then, the film was dried at 120°C for 3 minutes to form an adhesive resin layer having a thickness of 20 μm, which was then bonded to the substrate layer. The substrate layers 1 and 2 were bonded to the corona-treated surface. The substrate layer 3 was bonded to the acrylic layer side after peeling off the separator. The obtained laminate was heated in an oven at 40°C for 3 days to produce an adhesive film.

<Method for evaluating adhesive films>
(1) 60° peel strength after UV curing A silicon mirror wafer (8-inch single-sided mirror wafer) was cut into a size of 50 mm x 100 mm. The wafer mirror surface was ozone cleaned using a UV ozone cleaning device (manufactured by Technovision, UV-208) (ozone treatment time: 60 seconds). The wafer mirror surface was then wiped with ethanol to obtain an adherend wafer.
Under an environment of 23 ° C. and 50% RH, the adhesive film was cut to a width of 25 mm, the separator was peeled off, and the adhesive film was attached to the adherend wafer mirror surface via the adhesive resin layer using a hand roller, and left for 1 hour. After leaving it, the adhesive film was irradiated with ultraviolet light having a main wavelength of 365 nm at an irradiation intensity of 100 mW / cm ² using a high-pressure mercury lamp, and the adhesive film was irradiated with an ultraviolet light amount of 1080 mJ / cm ^2. Thereafter, the adherend wafer with the adhesive film attached was fixed to an adhesive / film peeling analysis device (VPA-2S, Kyowa Interface Science Co., Ltd.), and one end of the adhesive film was fixed to the load cell side with cellophane tape. The adhesive film was peeled off from the surface of the adherend wafer at a peel angle of 60 ° and a peel speed of 150 mm / min, and the 60 ° peel strength after UV irradiation was obtained from the stress at that time. The evaluation was performed with N = 2, and the values were averaged to obtain the measured value.

(2) 180° peel strength evaluation Adherend wafer:
The mirror surface of a silicon mirror wafer (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). The wafer mirror surface was then wiped with ethanol to prepare a substrate wafer.
Peel strength before UV exposure:
Under an environment of 23°C and 50% RH, the adhesive film was cut to a width of 50 mm, the separator was peeled off, and the adhesive film was attached to the mirror surface of the adherend wafer via its adhesive resin layer using a hand roller, and left for 1 hour. After leaving it, one end of the adhesive film was clamped using a tensile tester (Shimadzu Corporation, product name: Autograph AGS-X), and the adhesive film was peeled off from the surface of the adherend wafer at a peel angle of 180 degrees and a peel speed of 300 mm/min. The stress at that time was measured and converted to N/25 mm to obtain the peel strength. The evaluation was performed with N=2, and the values were averaged to obtain the measured value.
Peel strength after ultraviolet irradiation: In an environment of 23 ° C. and 50% RH, the adhesive film was cut to a width of 50 mm, the separator was peeled off, and the adhesive film was attached to the adherend wafer mirror surface via the adhesive resin layer using a hand roller, and left for 1 hour. After leaving it, the adhesive film was irradiated with ultraviolet rays having a main wavelength of 365 nm using a high-pressure mercury lamp at an irradiation intensity of 100 mW / cm ² and an ultraviolet amount of 1080 mJ / cm ² in an environment of 25 ° C. Then, using a tensile tester (Shimadzu Corporation, product name: Autograph AGS-X), one end of the adhesive film is clamped, and the adhesive film is peeled off from the surface of the adherend wafer at a peel angle of 180 degrees and a peel speed of 300 mm / min. The stress at that time was measured and converted to N / 25 mm to obtain the peel strength. The evaluation was performed with N = 2, and the values were averaged to obtain the measured value.

Adhesive residue rating:
The adherend wafer after the peeling was visually observed and evaluated according to the following criteria.
〇 (Good): No adhesive residue was found. × (Bad): Adhesive residue was found.

(3) Evaluation of Pre-Dicing Method Evaluation Wafer 1:
Using a dicing saw, the mirror surface of a mirror wafer (8-inch mirror wafer, diameter: 200±0.5 mm, thickness: 725±50 μm, one-sided mirror) was half-cut to obtain an 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 the evaluation wafer 1 was observed with an optical microscope, the kerf width was 35 μm.

Evaluation wafer 2:
Using a dicing saw, a first half cut was performed on the mirror surface of a mirror wafer (8-inch mirror wafer, diameter: 200±0.5 mm, thickness: 725±50 μm, one-sided mirror) (blade: Z09-SD2000-Y1 58×0.25A×40×45E-L, chip size: 5 mm×8 mm, cut depth: 15 μm, blade rotation speed: 30000 rpm). When observed with an optical microscope, the kerf width was 60 μm. Subsequently, a second half cut was performed (blade: ZH05-SD3500-N1-70-DD, chip size: 5 mm×8 mm, cut depth: 58 μm, blade rotation speed: 30000 rpm) to obtain an evaluation wafer 2.

First dicing method:
Using a tape laminator (DR3000II, manufactured by Nitto Denko Corporation), an adhesive film was attached to the half-cut surface of the evaluation wafer (23° C., attachment speed: 5 mm/min, attachment pressure: 0.36 MPa).
Next, the wafer was back-ground using a grinder (DISCO Corporation, DGP8760) (rough grinding and precision grinding, precision grinding amount: 40 μm, no polishing, thickness after grinding: 38 μm) to be divided into individual pieces.
The chipping during pre-dicing was evaluated visually after back grinding according to the following criteria.
◯ (Good): No chipping was observed, including in the triangular corners. × (Bad): Chip flying was observed, including in the triangular corners.

Furthermore, the adhesive film was irradiated with ultraviolet light and peeled off to evaluate adhesive residue after pre-dicing.
The ultraviolet irradiation was performed using a high pressure mercury lamp in an environment of 25° C., with ultraviolet rays having a dominant wavelength of 365 nm being irradiated at an irradiation intensity of 100 mW/cm ² to irradiate the adhesive film with an ultraviolet amount of 1080 mJ/cm ² .
The adhesive film was peeled off in the following manner. First, a dicing tape (used as a mounting tape) prepared separately was attached to an 8-inch wafer ring frame and the wafer side of the individualized wafer described above via the adhesive surface of the dicing tape using a wafer mounter (manufactured by Nitto Denko Corporation, MSA300). Next, the adhesive film was peeled off from the wafer notch with a peeling tape (manufactured by Lasting Systems, PET38REL) using a tape peeler (manufactured by Nitto Denko Corporation, HR3000III). The device peelability was evaluated according to the following criteria.
◯ (Good): The adhesive film was peeled off from the wafer on the first try. × (Bad): The adhesive film could not be peeled off from the wafer on the first try.

The adhesive residue on the individual wafers after the pre-dicing method was evaluated using an optical microscope (manufactured by Olympus Corporation) according to the following criteria.
〇 (Good): No adhesive residue was found. × (Bad): Adhesive residue was found.

[Example 1]
To 100 parts by mass of the (meth)acrylic resin solution 1 (solid content), 6.9 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM, product name: Omnirad 651) as a photoinitiator and 0.93 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, product name: Olestar P49-75S) were added to obtain an adhesive coating solution 1 for an adhesive resin layer. An adhesive film was produced by the above-mentioned method. In addition, based on the evaluation method described above, 60° peel strength evaluation, 180° peel strength evaluation, and pre-dicing method evaluation were performed after ultraviolet curing. The results are shown in Table 1.

[Examples 2 to 9 and Comparative Examples 1 and 2]
Each adhesive film was produced in the same manner as in Example 1, except that the types of the adhesive resin layer and the base material layer were changed to those shown in Table 1. In addition, 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): mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate NK Ester AD-TMP (manufactured by Shin-Nakamura Chemical Co., Ltd.): ditrimethylolpropane tetraacrylate

This application claims priority based on Japanese Patent Application No. 2020-125449, filed on July 22, 2020, the disclosure of which is incorporated herein in its entirety.

10 Base layer 20 Adhesive resin layer 30 Electronic component 30A Circuit formation surface 50 Adhesive film 100 Structure

Claims (6)

A step (A) of preparing a structure including an electronic component having a circuit formation surface and an adhesive film attached to the circuit formation surface side of the electronic component;
A step (B) of backgrinding a surface of the electronic component opposite to the circuit formation surface;
(C) a step of removing the adhesive film from the electronic component after irradiating the adhesive film with ultraviolet light;
A method for manufacturing an electronic device comprising at least
The adhesive film comprises a base layer and an ultraviolet-curable adhesive resin layer provided on one surface side of the base layer,
A method for producing an electronic device, wherein in the step (C), the 60° peel strength of the pressure-sensitive 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)
Using a tensile tester, the adhesive film after ultraviolet irradiation is peeled from the electronic component in a 60° direction under conditions of 23°C and a speed of 150 mm/min, and the strength (N/25 mm) at this time is defined as the 60° peel strength. 2. The method of claim 1, further comprising the steps of:
The step (A)
At least one step (A1) 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;
After the step (A1), a step (A2) of attaching the adhesive film to the circuit-forming surface side of the electronic component;
A method for manufacturing an electronic device comprising the steps of: 3. The method for manufacturing an electronic device according to claim 1, further comprising the steps of:
In the step (C), the adhesive film is irradiated with ultraviolet light at a dose of 200 mJ/ ^cm2 or more and 2000 mJ/cm2 or ^less to cure the adhesive resin layer with ultraviolet light, thereby reducing the adhesive strength of the adhesive resin layer, and then the adhesive film is removed from the electronic component. 4. The method for manufacturing an electronic device according to claim 1, further comprising the steps of:
The adhesive resin layer comprises a (meth)acrylic resin having a polymerizable carbon-carbon double bond in the molecule, and a photoinitiator. 5. The method for manufacturing an electronic device according to claim 1, further comprising the steps of:
The method for producing an electronic device, wherein the adhesive resin layer has a thickness of 5 μm or more and 300 μm or less. 6. The method for manufacturing an electronic device according to claim 1 ,
A method for manufacturing an electronic device, wherein the resin constituting the base layer contains one or more selected from polyolefin, polyester, polyamide, polyacrylate, polymethacrylate, polyvinyl chloride, polyvinylidene chloride, polyimide, polyetherimide, ethylene-vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, polysulfone, polyethersulfone, and polyphenylene ether.

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