JP7683243B2 - Adhesive film and evaluation method thereof, manufacturing method of semiconductor device, and integrated dicing/die bonding film - Google Patents

Description

This disclosure relates to an adhesive film used in the manufacturing process of a semiconductor device and a method for evaluating the same, as well as a method for manufacturing a semiconductor device and a dicing/die bonding integrated film.

Conventionally, semiconductor devices are manufactured through the following process. First, a semiconductor wafer is attached to a dicing adhesive sheet, and in this state, the semiconductor wafer is diced into individual semiconductor chips (dicing process). Then, a pick-up process, a pressure bonding process, a die bonding process, etc. are carried out.

Patent Document 1 discloses a dicing die bond film that has both the function of fixing a semiconductor wafer in a dicing process and the function of adhering a semiconductor chip to a substrate in a die bonding process. In the dicing process, the semiconductor wafer and adhesive layer are diced into individual pieces to obtain chips with adhesive pieces attached.

JP 2017-216273 A

Conventionally, as shown in FIG. 8, when relatively thin chips C1 to C4 are arranged in multiple stages on a substrate 30 with adhesive layer A interposed therebetween, peeling easily occurs between the first stage chip C1 and the second stage chip C2 due to warping stress of the chips C1 to C4. Patent Document 1 claims that problems caused by chip warping can be solved by setting the tensile storage modulus of the die bond film at 150°C before thermal curing within a specified range.

However, as adhesive films (die bond films) become thinner, it is becoming increasingly difficult to address various issues in the semiconductor manufacturing process using conventional indicators. According to the inventors' investigations, physical properties such as the tensile storage modulus, shear viscosity, and die shear of adhesive films do not necessarily correlate with process evaluation results. Therefore, the inventors decided to develop a new method for evaluating adhesive films that is useful for suppressing the occurrence of peeling in semiconductor packages due to chip warpage.

The present disclosure provides an adhesive film evaluation method that can evaluate adhesive films with a thickness of 20 μm or less and is useful for addressing the problem of peeling caused by chip warping in the manufacturing process of semiconductor devices. The present disclosure also provides an adhesive film that can sufficiently suppress the occurrence of the above-mentioned peeling, a method for manufacturing a semiconductor device using the same, and a dicing/die bonding integrated film that includes the above-mentioned adhesive film.

One aspect of the present disclosure relates to a method for evaluating an adhesive film used in a manufacturing process for a semiconductor device. The evaluation method includes a step of performing a tack test with a heated probe, and the thickness of the adhesive film to be evaluated is 20 μm or less.

The inventors observed the cross-section of the semiconductor package with an electron microscope and found that the mode of peeling occurring in the semiconductor package is not mainly the cohesive failure of the adhesive film, but peeling at the interface between the adhesive film and the chip. From this, the inventors inferred that peeling occurs within a short time after the chip is pressed, and came to the realization that it is necessary to capture the instantaneous adhesive strength (tackiness) of the adhesive film. Based on this realization, they came up with the idea of evaluating the adhesive film by a tack test. The tack test using a probe can be performed in accordance with the method described in ASTM D-2979 (Standard Test Method for Pressure-Sensitive Tack of Adhesives Using an Inverted Probe Machine).

The tack test can be performed using an apparatus that includes a stage that supports the adhesive film sample, and a probe that can be moved up and down relative to the stage and has a temperature setting. From the viewpoint of obtaining data with little variation, it is preferable to perform the tack test with a resin film interposed between the stage and the sample. Since the target of evaluation is a thin adhesive film, if the surfaces of the stage and the probe are not strictly horizontal, the probe surface is likely to press the sample in one direction, which makes it difficult to efficiently obtain data with little variation. By using a resin film, it is possible to avoid the probe surface pressing the sample in one direction. An example of a resin film is a polyimide film. Polyimide film has moderate elasticity and is heat resistant.

From the correlation between the results of the above evaluation method and the presence or absence of peeling in an actually manufactured semiconductor package, when an adhesive film satisfies both of the following conditions 1 and 2, the adhesive film can be judged to be good.
(Condition 1) In a tack test in which the probe temperature is set to 100° C., the tack is 2.5 N/5 mmφ or more.
(Condition 2) In a tack test in which the probe temperature is set to 120° C., the tack is 2.5 N/5 mmφ or more.

One aspect of the present disclosure relates to a method for manufacturing a semiconductor device. This manufacturing method includes the steps of preparing a laminated film including an adhesive film having a thickness of 20 μm or less, attaching the laminated film to a wafer so that the adhesive film is in contact with the surface of the wafer, producing chips with adhesive pieces by singulating the wafer and adhesive film, and adhering the chips with adhesive pieces to the surface of a substrate or another chip, and the adhesive film is an adhesive film that is judged to be good by the above evaluation method. According to this method, a highly reliable semiconductor device that is less likely to peel off internally can be manufactured.

One aspect of the present disclosure relates to an adhesive film used in the manufacturing process of a semiconductor device. This adhesive film has a thickness of 20 μm or less and is judged to be good by the above-mentioned evaluation method. One aspect of the present disclosure relates to an integrated dicing/die bonding film. This film comprises, in this order, a base film, an adhesive layer having a thickness of 20 μm or less, and a pressure-sensitive adhesive layer, and is composed of an adhesive film in which the adhesive layer is judged to be good by the above-mentioned evaluation method.

According to the present disclosure, a method for evaluating an adhesive film is provided that can evaluate an adhesive film having a thickness of 20 μm or less and is useful for dealing with the problem of peeling caused by warping of a semiconductor chip in the manufacturing process of a semiconductor device. In addition, according to the present disclosure, an adhesive film that can sufficiently suppress the occurrence of the above-mentioned peeling and a manufacturing method of a semiconductor device using the same, as well as a dicing/die bonding integrated film that includes the above-mentioned adhesive film are provided.

FIG. 1 is a cross-sectional view that illustrates an example of an apparatus for carrying out a tack test. FIG. 2(a) is a plan view showing a schematic diagram of one embodiment of a dicing and die bonding integrated film according to the present disclosure, and FIG. 2(b) is a schematic cross-sectional view taken along line BB in FIG. 2(a). FIG. 3 is a cross-sectional view showing a schematic diagram of one embodiment of a semiconductor device according to the present disclosure. FIG. 4 is a cross-sectional view showing a schematic example of a chip with an adhesive piece. 5(a) and 5(b) are cross-sectional views that typically show the process of producing the chip with adhesive piece shown in FIG. 6(a) to 6(c) are cross-sectional views that typically show the process of producing the chip with adhesive piece shown in FIG. 7A and 7B are cross-sectional views that typically show the process of manufacturing the semiconductor device shown in FIG. FIG. 8 is a cross-sectional view that typically shows a structure in which peeling has occurred between a first-stage chip and a second-stage chip. FIG. 9 is a cross-sectional view showing a schematic diagram of structures fabricated in the examples and comparative examples in order to reproduce peeling that occurs in the manufacturing process of a semiconductor device.

Below, the embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent parts will be given the same reference numerals, and duplicated descriptions will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, right, etc. will be based on the positional relationships shown in the drawings. The dimensional ratios of the drawings are not limited to the ratios shown. In this specification, (meth)acrylate means acrylate or the corresponding methacrylate. The same applies to other similar expressions such as (meth)acryloyl group and (meth)acrylic copolymer.

When terms such as "left," "right," "front," "back," "top," "bottom," "upper," and "lower" are used in the description and claims of this specification, they are intended for explanatory purposes and do not necessarily mean that the relative positions will be permanent. Furthermore, the term "layer" includes not only a structure with a shape formed over the entire surface when observed in a plan view, but also a structure with a shape formed on a portion of the surface. "A or B" may include either A or B, or both.

In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved. In addition, a numerical range indicated using "~" indicates a range that includes the numerical values before and after "~" as the minimum and maximum values, respectively.

In this specification, the content of each component in the composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. Furthermore, unless otherwise specified, the example materials may be used alone or in combination of two or more types. Furthermore, in the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced by the upper or lower limit of a numerical range of another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced by the values shown in the examples.

<Evaluation method of adhesive film>
The adhesive film evaluation method according to the present embodiment includes a step of performing a tack test with a heated probe. The adhesive film to be evaluated is used in the manufacturing process of a semiconductor device. The thickness of the adhesive film is 20 μm or less, and may be 18 μm or less, 15 μm or less, 12 μm or less, or 10 μm or less. The lower limit of the thickness of the adhesive film is not particularly limited, but may be, for example, 1 μm or 5 μm. A thickness of 20 μm or less of the adhesive film can realize a thin type of semiconductor device, while a thickness of 1 μm or more makes it easy to ensure sufficient adhesive strength.

Figure 1 is a cross-sectional view showing a schematic example of an apparatus for performing a tack test. The apparatus 10 shown in this figure includes a stage 1, a probe 2, and a holding jig 3. The probe 2 is pressed against a sample S (adhesive film) on the stage 1, and the adhesive strength is measured during the process of pulling the probe 2 away from the sample S. The probe 2 is movable in the vertical direction relative to the stage 1 and can be set at a temperature. The tip of the probe 2 is made of stainless steel and has a cylindrical shape. The tip surface of the probe 2 is sufficiently flat and smooth. The holding jig 3 is used to hold the sample S on the stage so that the sample S does not stick to the probe 2 and move upward. The load applied to the probe 2 is converted into an electrical signal, and data on the adhesive strength of the sample can be obtained. The tack test can be performed using a commercially available apparatus (for example, a tack tester TAC1000 (product name), manufactured by Rhesca Co., Ltd.).

The conditions for the tack test may be within the following ranges.
・Stage 1 temperature: 20-25°C (room temperature)
・Temperature of probe 2: 80 to 140°C
Probe 2 entry speed: 0.5 to 2.0 mm/sec. Pressure: 0.05 to 0.2 MPa
Pressurization time: 0.5 to 5 seconds. Probe 2 removal speed: 0.5 to 5.0 mm/second.

From the viewpoint of obtaining data with little variation, it is preferable to perform the tack test with a polyimide film 5 (resin film) interposed between the stage 1 and the sample S, as shown in FIG. 1. The thickness of the polyimide film 5 may be, for example, 50 to 200 μm or 100 to 150 μm. The tensile modulus of the polyimide film 5 is, for example, 2.5 to 4.5 GPa. This tensile modulus refers to a value measured in accordance with the method described in ASTM D-882. The heat resistance temperature of the polyimide film 5 is, for example, 250 to 320° C. Note that, although the case where the polyimide film 5 is used is exemplified here, other resin films may be used. The resin film may be any film that has the same elasticity as the polyimide film and heat resistance equal to or higher than the probe setting temperature, and specific examples thereof include aramid film, polyphenylene sulfide film, polyethylene naphthalate film, and polyethylene terephthalate film.

From the correlation between the results of the tack test evaluation method and the presence or absence of peeling in an actually manufactured semiconductor package, when an adhesive film satisfies both of the following conditions 1 and 2, the adhesive film can be judged to be good.
(Condition 1) In a tack test in which the probe temperature is set to 100° C., the tack is 2.5 N/5 mmφ or more.
(Condition 2) In a tack test in which the probe temperature is set to 120° C., the tack is 2.5 N/5 mmφ or more.

In order to determine whether an adhesive film satisfies conditions 1 and 2, the tack test is carried out under the following conditions.
Stage 1 temperature: 25°C
Temperature of probe 2: 100° C. or 120° C.
Probe 2 entry speed: 1.0 mm/sec. Pressure: 0.1 MPa
Pressurization time: 1.0 seconds. Probe 2 removal speed: 1.0 mm/second. Tip surface of probe 2: circular with a diameter of 5 mm.

In a tack test in which the probe temperature is set to 100°C, as described above, the tack is 2.5 N/5 mmφ or more (condition 1), but this value may be 3.0 N/5 mmφ or more. The upper limit of this value is, for example, 6.0 N/5 mmφ. In a tack test in which the probe temperature is set to 120°C, as described above, the tack is 2.5 N/5 mmφ or more (condition 2), but this value may be 3.0 N/5 mmφ or more. The upper limit of this value is, for example, 6.0 N/5 mmφ.

<Dicing and die bonding integrated film>
An adhesive film that satisfies both conditions 1 and 2 can be applied to the adhesive layer of a dicing-die bonding integrated film. FIG. 2(a) is a plan view showing a dicing-die bonding integrated film according to this embodiment, and FIG. 2(b) is a schematic cross-sectional view taken along line B-B in FIG. 2(a). A dicing-die bonding integrated film 20 (hereinafter, sometimes simply referred to as "film 20") includes a base film 11, a pressure-sensitive adhesive layer 13, and an adhesive layer 15 in this order. The adhesive layer 15 is made of an adhesive film that satisfies both conditions 1 and 2. In this embodiment, an embodiment in which one laminate of the pressure-sensitive adhesive layer 13 and the adhesive layer 15 is formed on the square base film 11 is illustrated, but the base film 11 may have a predetermined length (e.g., 100 m or more) and the laminate of the pressure-sensitive adhesive layer 13 and the adhesive layer 15 may be arranged at a predetermined interval so as to be aligned in the longitudinal direction.

Examples of the base film 11 include plastic films such as polytetrafluoroethylene film, polyethylene terephthalate film, polyethylene film, polypropylene film, polymethylpentene film, and polyimide film. The base film 11 may be subjected to a surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, and etching treatment, as necessary.

The adhesive layer 13 has a first surface F1 facing the base film 11 and a second surface F2 on the opposite side. The adhesive layer 13 is formed, for example, through a process of applying a coating liquid containing a resin composition having a suitable adhesive strength to the surface of the plastic film. The adhesive layer 13 may have a property that its adhesive strength decreases when irradiated with ultraviolet light, for example.

The adhesive layer 15 is provided so as to cover the center of the second surface F2 of the pressure-sensitive adhesive layer 13. As described above, the adhesive layer 15 is made of an adhesive film (film-like adhesive) that satisfies both conditions 1 and 2. The adhesive layer 15 is made of a thermosetting resin composition and has excellent adhesive strength (tackiness). By producing a semiconductor device using the adhesive layer 15, peeling due to warping of the chip within the semiconductor device can be sufficiently suppressed.

The adhesive layer 15 contains, for example, a thermosetting resin (hereinafter sometimes referred to as "component (A)"), a curing agent (hereinafter sometimes referred to as "component (B)"), and an elastomer (hereinafter sometimes referred to as "component (C)"). In addition to components (A), (B), and (C), the adhesive layer 15 may further contain an inorganic filler (hereinafter sometimes referred to as "component (D)"), a coupling agent (hereinafter sometimes referred to as "component (E)"), a curing accelerator (hereinafter sometimes referred to as "component (F)"), and other components. The adhesive layer 15 may be in a semi-cured (B stage) state and then in a fully cured (C stage) state after a curing process.

Component (A): Thermosetting Resin From the viewpoint of adhesiveness, the component (A) may contain an epoxy resin, or may be composed of one or more types of epoxy resins. The adhesive layer 15 contains, as the component (A), for example, an epoxy resin having a fluorene skeleton (hereinafter, sometimes referred to as “component (A1)”).

The (A1) component is, for example, a compound having a fluorene skeleton and an epoxy group in the molecule. The (A1) component can be used without any particular restrictions as long as it satisfies these conditions. By including the (A1) component as a thermosetting resin, the adhesive layer 15 can have excellent breakability by cooling expansion and excellent adhesion to the wafer. The inventors of the present disclosure believe that the reason for such an effect is as follows. Since the fluorene skeleton has a rigid and three-dimensionally bulky structure, it is presumed that molecules of other materials can enter the gaps in the structure. Therefore, the (A1) component is easily mixed with an elastomer (e.g., acrylic rubber), and is considered to modify the properties of the elastomer from soft and difficult to cut to hard and easy to cut. As a result, it is considered that the elastic modulus is improved, and therefore the adhesion to the wafer is also improved.

Component (A1) may be, for example, an epoxy resin represented by the following general formula (X):

In formula (X), Z ¹ and Z ² each independently represent a divalent aromatic hydrocarbon group. ^{Z 1} and Z ² may be the same or different, but may be the same. The divalent aromatic hydrocarbon group includes a group obtained by removing two hydrogen atoms directly bonded to the carbon atom constituting the ring from a monocyclic aromatic hydrocarbon (e.g., benzene) or a polycyclic aromatic hydrocarbon (e.g., bicyclic aromatic hydrocarbons such as naphthalene and indene; tricyclic aromatic hydrocarbons such as anthracene, phenanthrene, dihydrophenanthrene, and fluorene; tetracyclic aromatic hydrocarbons such as benzoanthracene, benzophenanthrene, benzofluorene, pyrene, and fluoranthene). The divalent aromatic hydrocarbon group includes a group obtained by removing two hydrogen atoms directly bonded to the carbon atom constituting the ring from an aromatic hydrocarbon formed by linking a plurality of these aromatic hydrocarbons (e.g., a biphenyldiyl group, a terphenyldiyl group, etc.). The divalent aromatic hydrocarbon group may be a benzenediyl group (a phenylene group) or a naphthalenediyl group (a naphthalenylene group).

The fluorene skeleton in the epoxy resin represented by formula (X) and the divalent aromatic hydrocarbon groups represented by ^Z1 and ^Z2 may have a substituent. Examples of the substituent include alkyl groups such as methyl, ethyl, and propyl groups; cycloalkyl groups such as cyclopentyl and cyclohexyl groups; aryl groups such as phenyl and naphthyl groups; aralkyl groups such as benzyl groups; acyl groups such as acetyl, propionyl, and benzoyl groups; alkoxy groups such as methoxy, ethoxy, propyloxy, and isopropyloxy groups; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups; cyano groups; carboxyl groups; nitro groups; amino groups; substituted amino groups (e.g., mono- or dialkylamino groups); and halogen atoms such as fluorine and chlorine atoms.

In formula (X), R ^1A and R ^2A each independently represent an alkylene group having 1 to 10 carbon atoms. R ^1A and R ^2A may be the same or different, but may be the same. Examples of the alkylene group include linear or branched alkylene groups having 1 to 10 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, and a hexamethylene group. The alkylene group may be an alkylene group having 2 to 6 carbon atoms, or an alkylene group having 2 or 3 carbon atoms.

In formula (X), p1 and p2 each independently represent an integer of 0 or more. p1 and p2 may be the same or different, but may be the same. p1 and p2 may be an integer of 0 to 4, or may be an integer of 1 to 4.

In formula (X), R ^1B , R ^1C , R ^1D , R ^1E , R ^1F , R ^2B , R ^2C , R ^2D , R ^2E , and R ^2F each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. R ^1B , R ^1C , R ^1D , R ^1E , R ^1F , R ^2B , R ^2C , R ^2D , R ^2E , and R ^2F may be the same or different. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, a pentyl group, and a hexyl group. R ^1B , R ^1C , R ^1D , R ^1E , R ^1F , R ^2B , R ^2C , R ^2D , R ^2E , and R ^2F may be a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or may be a hydrogen atom.

Commercially available epoxy resins represented by general formula (X) include, for example, PG-100, EG-200, and CG-500 (product names, all manufactured by Osaka Gas Chemicals Co., Ltd.).

The epoxy equivalent of component (A1) is not particularly limited, but may be 80 to 600 g/eq, 100 to 500 g/eq, or 200 to 400 g/eq. When the epoxy equivalent of component (A1) is within such a range, better reactivity and flowability tend to be obtained.

The content of the (A1) component may be 40 to 100% by mass, based on the total mass of the (A) component. When the content of the (A1) component is in this range, the effects of the present disclosure tend to be more pronounced. The content of the (A1) component may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more, based on the total mass of the (A) component.

The content of the (A1) component may be 1 mass% or more, 3 mass% or more, or 5 mass% or more, and may be 30 mass% or less, 20 mass% or less, or 15 mass% or less, based on the total mass of the adhesive layer 15. When the content of the (A1) component is 1 mass% or more, based on the total mass of the adhesive layer 15, the elastic modulus after curing tends to be better. When the content of the (A1) component is 30 mass% or less, based on the total mass of the adhesive layer 15, the flexibility before curing tends to be better.

In addition to the (A1) component, the (A) component may further contain an epoxy resin that does not have a fluorene skeleton in the molecule (hereinafter, sometimes referred to as the "(A2) component"). Examples of the (A2) component include bisphenol A type epoxy resins; bisphenol F type epoxy resins; bisphenol S type epoxy resins; phenol novolac type epoxy resins; cresol novolac type epoxy resins; bisphenol A novolac type epoxy resins; bisphenol F novolac type epoxy resins; stilbene type epoxy resins; triazine skeleton-containing epoxy resins; triphenol methane type epoxy resins; biphenyl type epoxy resins; xylylene type epoxy resins; biphenyl aralkyl type epoxy resins; naphthalene type epoxy resins; polyfunctional phenols, diglycidyl ether compounds of polycyclic aromatics such as anthracene, etc. Among these, the (A2) component may contain a cresol novolac type epoxy resin.

The epoxy equivalent of component (A2) is not particularly limited, but may be 80 to 600 g/eq, 100 to 500 g/eq, or 200 to 400 g/eq. When the epoxy equivalent of component (A1) is within such a range, better reactivity and flowability tend to be obtained.

The content of the (A2) component may be 0 to 60% by mass based on the total mass of the (A) component. The content of the (A2) component may be 50% by mass or less, 40% by mass or less, 30% by mass or less, or 20% by mass or less based on the total mass of the (A) component.

The content of the (A) component may be 1 mass% or more, 3 mass% or more, or 5 mass% or more, and may be 30 mass% or less, 20 mass% or less, or 15 mass% or less, based on the total mass of the adhesive layer 15. When the content of the (A) component is 1 mass% or more, based on the total mass of the adhesive layer 15, the elastic modulus after curing tends to be superior. When the content of the (A) component is 30 mass% or less, based on the total mass of the adhesive layer 15, the flexibility before curing tends to be superior.

Component (B): Curing Agent A commonly used curing agent for component (A) can be used. When component (A) contains an epoxy resin (comprising one or more epoxy resins), component (B) may be, for example, a phenolic resin, an ester compound, an aromatic amine, an aliphatic amine, an acid anhydride, etc. Among these, component (B) may be a phenolic resin from the viewpoint of reactivity and stability over time.

Any phenolic resin having a phenolic hydroxyl group in the molecule can be used without any particular limitation. Examples of phenolic resins include novolac-type phenolic resins obtained by condensing or co-condensing phenols such as phenol, cresol, resorcin, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol, etc. and/or naphthols such as α-naphthol, β-naphthol, dihydroxynaphthalene, etc. with a compound having an aldehyde group such as formaldehyde under an acidic catalyst, allylated bisphenol A, allylated bisphenol F, allylated naphthalenediol, phenol novolac, phenol aralkyl resins synthesized from phenols such as phenol and/or naphthols and dimethoxyparaxylene or bis(methoxymethyl)biphenyl, naphthol aralkyl resins, biphenyl aralkyl-type phenolic resins, phenyl aralkyl-type phenolic resins, etc.

The hydroxyl equivalent of the phenolic resin may be 70 g/eq or more, or 70 to 300 g/eq. If the hydroxyl equivalent of the phenolic resin is 70 g/eq or more, the storage modulus tends to be improved, and if it is 300 g/eq or less, it is possible to prevent defects due to the generation of foaming, outgassing, etc.

The softening point of the phenolic resin may be 90°C or higher, or may be 95°C or higher, 100°C or higher, 105°C or higher, 110°C or higher, or 115°C or higher. The upper limit of the softening point of the phenolic resin may be, for example, 200°C or lower. The softening point refers to a value measured by the ring and ball method in accordance with JIS K7234.

The content of component (B) may be 1 mass% or more, 2 mass% or more, or 3 mass% or more, and may be 20 mass% or less, 15 mass% or less, or 10 mass% or less, based on the total mass of the adhesive layer 15.

When the (A) component is an epoxy resin and the (B) component is a phenol resin, the ratio of the epoxy equivalent of the epoxy resin to the hydroxyl equivalent of the phenol resin (epoxy equivalent of the epoxy resin/hydroxyl equivalent of the phenol resin) may be 0.30/0.70 to 0.70/0.30, 0.35/0.65 to 0.65/0.35, 0.40/0.60 to 0.60/0.40, or 0.45/0.55 to 0.55/0.45 from the viewpoint of curability. When the equivalent ratio is 0.30/0.70 or more (epoxy equivalent of the epoxy resin is 0.30 or more), more sufficient curability tends to be obtained. When the equivalent ratio is 0.70/0.30 or less (epoxy equivalent of the epoxy resin is 0.70 or less), it is possible to prevent the viscosity from becoming too high, and more sufficient fluidity can be obtained.

The total content of the (A) component and the (B) component may be 1 mass% or more, 5 mass% or more, or 10 mass% or more based on the total mass of the adhesive layer 15. When the total content of the (A) component and the (B) component is in such a range, the adhesiveness tends to be further improved. From the viewpoint of handleability, the total content of the (A) component and the (B) component may be 40 mass% or less, 30 mass% or less, or 20 mass% or less based on the total mass of the adhesive layer 15.

(C) component: elastomer Examples of the (C) component include acrylic resin, polyester resin, polyamide resin, polyimide resin, silicone resin, butadiene resin; modified products of these resins, and the like. These may be used alone or in combination of two or more. Among these, the (C) component may be an acrylic resin (acrylic rubber) having a structural unit derived from a (meth)acrylic acid ester as a main component, since it has less ionic impurities and is more excellent in heat resistance, it is easier to ensure the connection reliability of the semiconductor device, and it has more excellent fluidity. The content of the structural unit derived from a (meth)acrylic acid ester in the (C) component may be, for example, 70% by mass or more, 80% by mass or more, or 90% by mass or more based on the total amount of the structural units. The acrylic resin (acrylic rubber) may contain a structural unit derived from a (meth)acrylic acid ester having a crosslinkable functional group such as an epoxy group, an alcoholic or phenolic hydroxyl group, or a carboxyl group.

The glass transition temperature (Tg) of the (C) component may be 5°C or higher, or may be 10°C or higher. When the Tg of the (C) component is 5°C or higher, it is possible to further improve the adhesiveness of the adhesive layer 15, and furthermore, it is possible to prevent the flexibility of the adhesive layer 15 from becoming too high. This makes it easier to cut the adhesive layer 15 during wafer dicing, and it is possible to prevent the occurrence of burrs. The upper limit of the Tg of the (C) component is not particularly limited, but may be, for example, 55°C or lower, 50°C or lower, 45°C or lower, 40°C or lower, 35°C or lower, 30°C or lower, or 25°C or lower. When the Tg of the (C) component is 55°C or lower, it is possible to suppress the decrease in the flexibility of the adhesive layer 15. This tends to make it easier to sufficiently fill voids when the adhesive layer 15 is attached to the wafer. It is also possible to prevent chipping during dicing due to a decrease in adhesion with the wafer. Here, the glass transition temperature (Tg) refers to a value measured using a DSC (differential scanning calorimeter) (for example, Thermo Plus 2, manufactured by Rigaku Corporation). The Tg of the (C) component can be adjusted to a desired range by adjusting the type and content of the structural unit constituting the (C) component (when the (C) component is an acrylic resin (acrylic rubber), the structural unit derived from a (meth)acrylic acid ester).

The weight average molecular weight (Mw) of component (C) may be 100,000 or more, 300,000 or more, or 500,000 or more, and may be 3,000,000 or less, 2,000,000 or less, or 1,000,000 or less. When the Mw of component (C) is in this range, the film formability, film strength, flexibility, tackiness, etc. can be appropriately controlled, and the reflowability and embeddability can be improved. Here, Mw means a value measured by gel permeation chromatography (GPC) and converted using a calibration curve based on standard polystyrene.

Commercially available products of component (C) include SG-P3 and SG-80H (both manufactured by Nagase ChemteX Corporation) and KH-CT-865 (manufactured by Hitachi Chemical Co., Ltd.).

The content of the (C) component may be 30% by mass or more, 40% by mass or more, or 45% by mass or more, based on the total mass of the adhesive layer 15. When the content of the (C) component is in this range, the thin film coating property tends to be better. The content of the (C) component may be 80% by mass or less, 70% by mass or less, or 65% by mass or less, based on the total mass of the adhesive layer 15. When the content of the (C) component is in this range, the contents of the (A) component and the (B) component can be sufficiently secured, and it tends to be compatible with other properties.

(D) component: inorganic filler Examples of the (D) component include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, boron nitride, silica, and the like. These may be used alone or in combination of two or more. Among these, the (D) component may be silica from the viewpoint of adjusting the melt viscosity. The shape of the (D) component is not particularly limited, but may be spherical.

From the viewpoint of fluidity and storage modulus, the average particle size of component (D) may be 0.7 μm or less, 0.6 μm or less, or 0.5 μm or less. The average particle size of component (D) may be, for example, 0.01 μm or more. Here, the average particle size refers to a value calculated by conversion from the BET specific surface area.

The content of the (D) component may be 60% by mass or less, 50% by mass or less, or 45% by mass or less, based on the total mass of the adhesive layer 15. When the content of the (D) component is in such a range, thin film coating properties tend to be superior. The content of the (D) component may be 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total mass of the adhesive layer 15.

Component (E): Coupling Agent Component (E) may be a silane coupling agent. Examples of the silane coupling agent include γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltrimethoxysilane.

Component (F): Curing Accelerator Examples of the component (F) include imidazoles and their derivatives, organic phosphorus compounds, secondary amines, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more. Among these, the component (F) may be imidazoles and their derivatives from the viewpoint of reactivity.

Examples of imidazoles include 2-methylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2-methylimidazole. These may be used alone or in combination of two or more.

The adhesive layer 15 may further contain other components. Examples of the other components include pigments, ion capture agents, and antioxidants.

The total content of the (E) component, the (F) component, and other components may be 0.1 mass% or more, 0.3 mass% or more, or 0.5 mass% or more, based on the total mass of the adhesive layer 15, and may be 20 mass% or less, 10 mass% or less, or 5 mass% or less.

<Semiconductor Device>
3 is a cross-sectional view showing a semiconductor device according to this embodiment. The semiconductor device 50 shown in this figure includes a substrate 30, four chips C1, C2, C3, and C4 stacked on the surface of the substrate 30, wires W1, W2, W3, and W4 electrically connecting electrodes (not shown) on the surface of the substrate 30 to the four chips C1, C2, C3, and C4, and a sealing layer 35 sealing them.

The substrate 30 may be, for example, an organic substrate or a metal substrate such as a lead frame. From the viewpoint of suppressing warping of the semiconductor device 50, the thickness of the substrate 30 may be, for example, 70 to 140 μm, or 80 to 100 μm.

The four chips C1, C2, C3, and C4 are laminated via the cured product 15c of the adhesive piece 15p. The shape of the chips C1, C2, C3, and C4 in plan view is, for example, a square or a rectangle. The area of the chips C1, C2, C3, and C4 in plan view is 30 to 250 mm ² , and may be 40 to 200 mm ² or 50 to 150 mm ^2. The length of one side of the chips C1, C2, C3, and C4 in plan view is, for example, 6.0 mm or more, and may be 7.0 to 18 mm or 8.0 to 15 mm. The thickness of the chips C1, C2, C3, and C4 is, for example, 10 to 150 μm, and may be 20 to 80 μm. The length of one side of the four chips C1, C2, C3, and C4 may be the same or different from each other, and the same applies to the thickness. In addition, the four chips C1, C2, C3, and C4 may be relatively small in size, i.e., the area of the chips C1, C2, C3, and C4 may be less than 30 ^mm2 , for example, 0.1 to 20 ^mm2 or 1 to 15 ^mm2 .

<Chip with adhesive>
Fig. 4 is a cross-sectional view showing an example of a chip with adhesive pieces. The chip with adhesive pieces 25 shown in Fig. 4 is composed of an adhesive piece 15p and a chip C. As shown in this figure, the adhesive piece 15p and the chip C1 are substantially the same size. The same is true for the adhesive piece 15p and the chips C2, C3, and C4.

An example of a method for producing the chip 25 with adhesive pieces will be described. First, a protective film (also called BG tape) is attached to the circuit surface Wa of the wafer W. A laser is irradiated onto the wafer W to form a plurality of intended cutting lines L (stealth dicing). Then, as necessary, the wafer W is subjected to back grinding and polishing processes. Note that, although stealth dicing using a laser is exemplified here, the wafer W may be half-cut with a blade instead. Half-cutting does not mean cutting the wafer W, but rather forming a cut corresponding to the intended cutting lines L of the wafer W. The wafer W may be single crystal silicon, polycrystalline silicon, various ceramics, or compound semiconductors such as gallium arsenide.

Next, as shown in FIG. 5(a), the film 20 is attached to the back surface Wb of the wafer W so that the adhesive layer 15 is in contact with the back surface Wb. A dicing ring DR is attached to the peripheral portion 13a of the adhesive layer 13. The wafer W and the adhesive layer 15 are then singulated by cooling and expanding under a temperature condition of 0 to -15°C. That is, as shown in FIG. 5(b), tension is applied to the base film 11 by pushing up the inner region 11a of the dicing ring DR in the base film 11 with the ring Ra. As a result, the wafer W is divided along the planned cutting line L, and the adhesive layer 15 is divided into adhesive pieces 15p. A plurality of chips 25 with adhesive pieces are obtained on the surface of the adhesive layer 13. The chips 25 with adhesive pieces are composed of the chips C and the adhesive pieces 15p.

The inner region 11a of the dicing ring DR on the base film 11 is heated to cause the inner region 11a to shrink. FIG. 6(a) is a cross-sectional view that shows a schematic diagram of the inner region 11a being heated by blowing with a heater H. By causing the inner region 11a to shrink in an annular shape and applying tension to the base film 11, the spacing between adjacent adhesive chips 25 can be increased. This can further reduce the occurrence of pick-up errors and improve the visibility of the adhesive chips 25 during the pick-up process.

Next, as shown in Fig. 6(b), the adhesive force of the adhesive layer 13 is reduced by irradiation with activation energy (e.g., ultraviolet light UV). The amount of irradiation of the active energy rays to the adhesive layer 13 is, for example, 10 to 1000 mJ/ ^cm2 , and may be 100 to 700 mJ/ ^cm2 or 200 to 500 mJ/ ^cm2 . Thereafter, as shown in Fig. 6(c), the chip 25 with the adhesive piece attached is pushed up by a push-up jig 42 to be peeled off from the adhesive layer 13, and the chip 25 with the adhesive piece attached is picked up by suction with a suction collet 44.

<Method of Manufacturing Semiconductor Device>
A method for manufacturing the semiconductor device 50 will be described. First, as shown in FIG. 7(a), the first-stage chip C1 is pressure-bonded onto the surface of the substrate 30. That is, the chip C1 is pressure-bonded to a predetermined position on the substrate 30 via the adhesive piece 15p of the chip 25 with adhesive piece. This pressure-bonding process is preferably carried out for 0.5 to 3.0 seconds under conditions of, for example, 80 to 180° C. and 0.01 to 0.50 MPa. Next, the adhesive piece 15p is cured by heating. This curing process is preferably carried out for 5 minutes or more under conditions of, for example, 60 to 175° C. and 0.01 to 1.0 MPa. As a result, the adhesive piece 15p is cured to become a cured product 15c. The curing process of the adhesive piece 15p may be carried out under a pressurized atmosphere from the viewpoint of reducing voids.

In the same manner as chip C1 is placed on substrate 30, second-tier chip C2 is placed on the surface of chip C1. Furthermore, third-tier and fourth-tier chips C3 and C4 are placed to produce structure 40 shown in FIG. 7(b). After chips C1, C2, C3, and C4 are electrically connected to substrate 30 with wires W1, W2, W3, and W4, the chips and wires are sealed with sealing layer 35 to complete semiconductor device 50 shown in FIG. 3.

Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above embodiments. For example, the above embodiments illustrate the case where the wafer W is diced by stealth dicing, but the wafer W may be diced using a blade.

The present disclosure will be explained in more detail below based on examples, but the present invention is not limited to these examples. Unless otherwise specified, all chemicals used were reagents.

(Examples 1 and 2 and Comparative Examples 1 and 2)
<Preparation of adhesive varnish>
Cyclohexanone was added to a mixture of components (A), (B), and (D) with the components and contents (unit: parts by mass) shown in Table 1, and mixed by stirring. Component (C) was added to this with the components and contents (unit: parts by mass) shown in Table 1, and stirred, and further components (E) and (F) were added and stirred until each component was uniform, to prepare an adhesive varnish. Note that each component shown in Table 1 has the following meaning, and the numerical value shown in Table 1 means the mass part of the solid content.

Component (A): Epoxy resin Component (A1): Epoxy resin having a fluorene skeleton (A1-1) PG-100 (product name, manufactured by Osaka Gas Chemicals Co., Ltd., epoxy resin having a fluorene skeleton, epoxy equivalent: 260 g/eq)
(A1-2) CG-500 (product name, manufactured by Osaka Gas Chemicals Co., Ltd., epoxy resin having a fluorene skeleton, epoxy equivalent: 310 g/eq)
Component (A2): Epoxy resin not having a fluorene skeleton (A2-1) N-500P-10 (product name, manufactured by DIC Corporation, o-cresol novolac type epoxy resin, epoxy equivalent: 204 g/eq)
(A2-2) EXA-830CRP (product name, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol F type epoxy resin, epoxy equivalent: 159 g/eq)

Component (B): Curing agent (B-1) PSM-4326 (trade name, manufactured by Gun-ei Chemical Industry Co., Ltd., phenol novolac type phenolic resin, hydroxyl equivalent: 105 g/eq, softening point: 118 to 122° C.)
(B-2) GPH-103 (trade name, manufactured by Nippon Kayaku Co., Ltd., biphenylaralkyl type phenolic resin, hydroxyl equivalent: 220 to 240 g/eq, softening point: 99 to 106° C.)
(B-3) MEH-7800M (product name, manufactured by Meiwa Chemical Industry Co., Ltd., phenol novolac type phenolic resin, hydroxyl equivalent: 175 g/eq, softening point: 78° C.)

Component (C): Elastomer (C-1) Methyl ethyl ketone solution of acrylic rubber (acrylic rubber obtained by modifying some of the structural units of acrylic rubber SG-P3 (product name, manufactured by Nagase ChemteX Corporation), weight average molecular weight: 800,000, Tg: 12°C)

Component (D): Inorganic filler (D-1) R972 (product name, manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size: 0.016 μm)
(D-2) SC2050-HLG (product name, manufactured by Admatechs Co., Ltd., silica filler dispersion, average particle size: 0.50 μm)
(D-3) Prototype silica filler (prototype, manufactured by Admatechs Co., Ltd., silica filler dispersion, average particle size: 0.2 μm)

Component (E): Coupling agent (E-1) Y-9669 (product name, manufactured by Momentive Performance Materials Japan, 3-phenylaminopropyltrimethoxysilane)
(E-2) A-189 (trade name, manufactured by Nippon Unicar Co., Ltd., γ-mercaptopropyltrimethoxysilane)
(E-3) Z-6119 (product name, manufactured by Dow Corning Toray Co., Ltd., ureidopropyltriethoxysilane)

Component (F): Curing accelerator (F-1) 2PZ-CN (trade name, manufactured by Shikoku Chemical Industry Co., Ltd., 1-cyanoethyl-2-phenylimidazole)

<Preparation of adhesive film>
The prepared adhesive varnish was filtered through a 100 mesh filter and vacuum degassed. A 38 μm thick polyethylene terephthalate (PET) film with a release treatment was prepared as a support film, and the adhesive varnish after vacuum degassing was applied onto the PET film. The applied adhesive varnish was heated and dried in two stages at 90° C. for 5 minutes and then at 130° C. for 5 minutes to obtain adhesive films (thickness: 10 μm) of Examples 1 and 2 and Comparative Examples 1 and 2 in a B-stage state.

<Preparation of dicing film>
[Synthesis of acrylic copolymer]
The following components were used as raw materials and ethyl acetate was used as a solvent to obtain a copolymer by solution radical polymerization.
2-Ethylhexyl acrylate: 78 parts by mass 2-Hydroxyethyl acrylate: 20 parts by mass Methacrylic acid: 2 parts by mass This acrylic copolymer was reacted with 8 parts by mass of 2-methacryloyloxyethyl isocyanate to synthesize a radiation-reactive acrylic copolymer having a carbon-carbon double bond. In the above reaction, 0.05 parts by mass of hydroquinone monomethyl ether was used as a polymerization inhibitor. The weight average molecular weight of the synthesized acrylic copolymer was measured by GPC and found to be 800,000.

The acrylic copolymer thus obtained was mixed with 8.0 parts by mass (solid content equivalent) of a polyisocyanate compound (product name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) as a curing agent, and 0.5 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator to prepare a radiation-curable adhesive solution. Next, the radiation-curable adhesive solution thus obtained was applied to a polyethylene terephthalate release film (thickness: 38 μm) and dried so that the thickness after drying would be 10 μm. After that, an ionomer resin film (Himilan 1855, thickness 90 μm) in which the molecules of an ethylene-methacrylic acid copolymer, which had been corona discharge-treated on one side, were crosslinked with metal ions, was bonded to the adhesive layer. The bonded sample was aged in a thermostatic chamber at 40°C for 72 hours to produce a dicing film.

<Production of integrated dicing and die bonding film>
The adhesive films according to the Examples and Comparative Examples were laminated to the pressure-sensitive adhesive layer of the dicing film obtained as described above, thereby obtaining dicing and die bonding integrated films according to the Examples and Comparative Examples.

[Tack test]
Samples for performing the tack test were prepared as follows.
(1) The adhesive strength of the dicing film was reduced by irradiating the dicing film side of the dicing/die bonding integrated film with ultraviolet light under the following ultraviolet light irradiation conditions:
・UV light intensity: 100mW/ ^cm2
・UV irradiation dose: 150 mJ/ ^cm2
(2) A dicing/die bonding integrated film was laminated onto the polyimide film so that the adhesive film was in contact with the surface of the polyimide film. The following polyimide films were used. The lamination conditions were as follows:
(Polyimide film)
Kapton 500H (product name, manufactured by DuPont-Toray Co., Ltd.)
Thickness: 125 μm
Tensile modulus: 3.35 GPa
・Heat-resistant temperature: 270℃
(Lamination conditions)
・Temperature: 65℃
Speed: 5 mm/sec. (3) After lamination, the laminate was left at room temperature for one day to enhance the adhesion between the polyimide film and the adhesive film.
(4) The laminate was cut into a size of 40 mm length x 40 mm width, and the dicing film was peeled off. In this way, a plurality of samples were obtained for each of the examples and the comparative examples.

The sample was set on the stage of a tack tester (TAC1000 (product name), manufactured by Rhesca Co., Ltd.) with the adhesive film facing up. The adhesive films according to the examples and comparative examples were subjected to a tack test under the following conditions.
Stage temperature: 25°C
Probe temperature: 100°C or 120°C
Probe entry speed: 1.0 mm/sec. Pressure: 0.1 MPa
Pressurization time: 1.0 seconds; Probe removal speed: 1.0 mm/second; Probe tip surface: circular with a diameter of 5 mm; Probe material: SUS304

For each of the examples and comparative examples, nine measurements were performed, and the average of the seven measurements excluding the maximum and minimum values was taken as the tack (N/5 mmφ). The results are shown in Table 2.

As shown in Table 2, both the adhesive films of Examples 1 and 2 satisfy conditions 1 and 2 and are judged to be good. The adhesive film of Comparative Example 1 does not satisfy either condition 1 or 2. The adhesive film of Comparative Example 2 satisfies condition 1 but does not satisfy condition 2.

[Reproduction of peeling in the manufacturing process of semiconductor devices]
In order to reproduce peeling in the manufacturing process of a semiconductor device, the dicing and die bonding integrated film of Example 1 was used to fabricate a chip with an adhesive piece having the configuration shown in Fig. 4 through the steps shown in Fig. 5 and Fig. 6. The chip sizes were as follows:
Thickness: 36 μm
・ Length: 6mm
Width: 12mm

Eight chips with adhesive pieces were used to fabricate a structure as shown in Fig. 9. The structure 90 in Fig. 9 is composed of a substrate 30, a silicon spacer 32, and eight stages of chips with adhesive pieces S1 to S8. The pressure bonding conditions for the chips with adhesive pieces were set to the following two types, and two structures were fabricated.
・120℃/15N/1 second ・120℃/7.5N/1 second

The structures of Example 2 and Comparative Examples 1 and 2 were produced in the same manner as above, except that the dicing/die bonding integrated films of Example 2 and Comparative Examples 1 and 2 were used. For the structures of the Examples and Comparative Examples, the separation distance D shown in Figure 9 was measured to evaluate the adhesion of the first-stage adhesive chip S1 to the surface of the silicon spacer. The results are shown in Table 3.

In the structures of Examples 1 and 2, the adhesive layer had a thickness of 10 μm, but the separation distance D was 30 μm or less, and peeling was suppressed. In contrast, the structures of Comparative Examples 1 and 2 had a separation distance D of more than 30 μm, and the adhesive layer having a thickness of 10 μm was not able to sufficiently suppress peeling. The evaluation results shown in Table 2 are consistent with the results shown in Table 3.

1...stage, 2...probe, 3...holding jig, 5...polyimide film (resin film), 10...device for performing tack test, 11...base film, 13...adhesive layer, 15...adhesive layer, 15c...cured adhesive piece, 15p...adhesive piece, 20...integrated dicing/die bonding film, 25...chip with adhesive piece, 30...substrate, 35...sealing layer, 40...structure, 50...semiconductor device, C, C1, C2, C3, C4...chip, S...sample, W...wafer.

Claims (5)

A method for evaluating an adhesive film used in a manufacturing process of a semiconductor device, comprising:
performing a tack test with a heated probe;
The thickness of the adhesive film to be evaluated is 20 μm or less,
The method for evaluating an adhesive film, wherein the adhesive film is judged to be good when it satisfies both of the following conditions 1 and 2 .
(Condition 1) In the tack test in which the probe temperature is set to 100° C., the tack is 2.5 N/5 mmφ or more.
(Condition 2) In the tack test in which the probe temperature is set to 120° C., the tack is 2.5 N/5 mmφ or more. Using an apparatus including a stage for supporting a sample of the adhesive film and a probe that is movable up and down relative to the stage and has a temperature setting function,
The method for evaluating an adhesive film according to claim 1 , wherein the tack test is performed with a resin film interposed between the stage and the sample. preparing a laminated film including an adhesive film having a thickness of 20 μm or less;
attaching the laminate film to the wafer so that the adhesive film is in contact with a surface of the wafer;
producing adhesive chips by singulating the wafer and the adhesive film;
Adhering the adhesive stripped chip onto a surface of a substrate or other chip;
Including,
The adhesive film is an adhesive film that is judged to be good by the evaluation method according to claim 1 or 2 ,
The method for manufacturing a semiconductor device, wherein the adhesive film contains (A) a thermosetting resin, (B) a curing agent, and (C) an elastomer having a glass transition temperature of 5 to 55°C . An adhesive film used in a manufacturing process of a semiconductor device,
The thickness is 20 μm or less,
In the evaluation method according to claim 1 or 2 , the evaluation result is judged to be good ,
The adhesive film comprises (A) a thermosetting resin, (B) a curing agent, and (C) an elastomer having a glass transition temperature of 5 to 55°C . A base film;
An adhesive layer having a thickness of 20 μm or less;
An adhesive layer;
in this order,
The adhesive layer is composed of an adhesive film that is judged to be good by the evaluation method according to claim 1 or 2 ,
The adhesive film comprises (A) a thermosetting resin, (B) a curing agent, and (C) an elastomer having a glass transition temperature of 5 to 55°C .

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