Film for forming protective film, composite sheet for forming protective film, method for manufacturing semiconductor device, and semiconductor device

Abstract

To provide a film for forming a protective film that can suppress chipping of a wafer when the wafer is cut with a dicing blade.SOLUTION: A thermosetting protective film for forming a protective film to be applied to the circuit surface of a wafer contains a filler, and in an electron microscope image obtained by observing a cross section of at least one of the following samples (1) to (3) in a specific observation area, when a perfect circle is placed between the fillers, the maximum diameter of the perfect circle is less than 3.0 μm. Sample (1): Uncured protective film for forming a protective film. Sample (2): Protective film obtained by thermally curing the protective film for forming a protective film at 130°C for 4 hours without pressure. Sample (3): Protective film obtained by thermally curing the protective film for forming a protective film at 130°C for 4 hours under pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film for forming a protective film, a composite sheet for forming a protective film, a method for manufacturing a semiconductor device, and a semiconductor device. [Background technology]

[0002] In recent years, as electronic devices have become smaller and thinner, there has been an increasing demand for thinner and smaller semiconductor packages. To address this issue, a flip-chip mounting method has been proposed, in which protruding electrodes such as bumps are formed on the electrodes of a chip, and the electrodes of the substrate and the electrodes of the chip are directly connected via the protruding electrodes, instead of the conventional wire bonding method that uses metal wires to connect semiconductor elements.

[0003] Incidentally, a protective film may be provided on the protruding electrode forming surface of a wafer with protruding electrodes, in order to protect the joint between the protruding electrodes and the semiconductor wafer (also called the "bump neck" if the protruding electrodes are bumps). For example, in Patent Document 1, the ratio of the storage shear modulus of the film for forming a protective film (the adhesive layer in Patent Document 1) to the storage shear modulus of the buffer layer (the thermoplastic resin layer in Patent Document 1) at the application temperature when the composite sheet for forming a protective film (the protective tape in Patent Document 1) is applied to a wafer is adjusted to be 0.01 or less, thereby suppressing resin residue on the bumps when other layers are removed from the composite sheet for forming a protective film while leaving the film for forming a protective film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-206006 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a laminate in which a protective film is formed on a wafer, the wafer is cut together with the protective film using a dicing blade to be divided into individual pieces. During this process, chipping may occur in the wafer. From the viewpoint of improving the yield of semiconductor manufacturing equipment (the individual pieces of the laminate), it is desired to reduce chipping.

[0006] The present invention aims to provide a film for forming a protective film that can prevent chipping of a wafer when cutting with a dicing blade, a composite sheet for forming a protective film that has the film for forming a protective film, a method for manufacturing a semiconductor device using these, and a semiconductor device. [Means for solving the problem]

[0007] According to the present invention, the following [1] to

[15] are provided. [1] A thermosetting protective film to be attached to the circuit surface of a wafer, Contains a filler, A film for forming a protective film, in which, in an electron microscope image obtained by observing a cross section of at least one of the following samples (1) to (3) in the observation area below, the maximum diameter of the perfect circle when placed between the fillers is less than 3.0 μm. Sample (1): Uncured protective film-forming film Sample (2): A protective film obtained by thermally curing the protective film-forming film at 130°C for 4 hours without pressure. Sample (3): A protective film obtained by thermally curing the protective film-forming film at 130°C under pressure for 4 hours. <Observation area> When the thickness direction of the samples (1) to (3) is defined as the vertical direction and the direction perpendicular to the thickness direction of the samples (1) to (3) is defined as the horizontal direction, a vertical area of ​​10% of the thickness is excluded from the surface opposite to the surface to be attached to the adherend, and the observation area is the surface formed by a side A of 15 μm from the end of the excluded area toward the surface to be attached to the adherend and a horizontal side B of 33 μm. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area. [2] The film for forming a protective film according to [1] above, wherein the wafer is a wafer with a protruding electrode. [3] The film for forming a protective film according to the above [1] or [2], which contains an acetal resin. [4] The film for forming a protective film according to any one of the above [1] to [3], wherein the filler contains silica. [5] The film for forming a protective film according to any one of the above [1] to [4], wherein the average particle size of the filler is 100 nm or less. [6] The film for forming a protective film according to any one of the above [1] to [5], which has a glass transition temperature of 60°C or higher. [7] A composite sheet for forming a protective film, having a laminated structure of a substrate and the film for forming a protective film according to any one of the above [1] to [6]. [8] The composite sheet for forming a protective film according to [7] above, further comprising a buffer layer between the substrate and the film for forming a protective film. [9] The composite sheet for forming a protective film according to [8] above, further comprising an intermediate release layer between the buffer layer and the film for forming a protective film.

[10] A step of attaching the film for forming a protective film according to any one of the above [1] to [6] to a wafer; A method for manufacturing a semiconductor device, comprising a step of dividing a laminate of the film for forming a protective film and the wafer, or a laminate of the protective film obtained by thermally curing the film for forming a protective film and the wafer, by blade dicing.

[11] A step of attaching the film surface for forming a protective film of the composite sheet for forming a protective film according to any one of the above [7] to [9] to a wafer; A method for manufacturing a semiconductor device, comprising a step of dividing a laminate of the film for forming a protective film and the wafer, or a laminate of the protective film obtained by thermally curing the film for forming a protective film and the wafer, by blade dicing.

[12] The method for manufacturing a semiconductor device according to

[10] or

[11] above, wherein the thermal curing is carried out without applying pressure.

[13] A wafer protection method comprising: attaching a film for forming a protective film according to any one of [1] to [6] above to a wafer; and then dicing a laminate of the film for forming a protective film and the wafer, or a laminate of a protective film obtained by thermally curing the film for forming a protective film and the wafer, by blade dicing, thereby suppressing chipping of the wafer.

[14] A wafer protection method comprising: attaching the protective film forming film surface of the composite sheet for forming a protective film described in any one of [7] to [9] above to a wafer; and then dicing a laminate of the protective film forming film and the wafer, or a laminate of a protective film formed by heat-curing the protective film forming film and the wafer, by blade dicing, thereby suppressing chipping of the wafer.

[15] A semiconductor device in which a protective film is laminated on a circuit surface of a wafer or a chip of the wafer, In an electron microscope image obtained by observing a cross section of the protective film in the observation region described below, the semiconductor device has a perfect circle disposed between the fillers, and the maximum diameter of the perfect circle is less than 3.0 μm. <Observation area> When the thickness direction of the protective film is defined as the vertical direction and the direction perpendicular to the thickness direction of the protective film is defined as the horizontal direction, a vertical area of ​​10% of the thickness is excluded from the surface opposite to the surface to be attached to the substrate, and the observation area is the surface formed by a 15 μm side A and a 33 μm horizontal side B from the end of the excluded area toward the surface to be attached to the substrate. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a film for forming a protective film that can suppress chipping of a wafer when cutting with a dicing blade, the film for forming a protective film, a method for manufacturing a semiconductor device using the film, and a semiconductor device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a first aspect of a composite sheet for forming a protective film according to the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a second aspect of the composite sheet for forming a protective film of the present embodiment. [Figure 3] FIG. 2 is a schematic cross-sectional view showing a third aspect of the composite sheet for forming a protective film of the present embodiment. [Figure 4] FIG. 3 is a schematic cross-sectional view showing a fourth aspect of the composite sheet for forming a protective film of the present embodiment. [Figure 5] FIG. 10 is a schematic cross-sectional view showing a fifth aspect of the composite sheet for forming a protective film of the present embodiment. [Figure 6] 5A to 5C are schematic cross-sectional views showing a part of the method for manufacturing the semiconductor device according to the present embodiment. [Figure 7] 5A to 5C are schematic cross-sectional views showing a part of the method for manufacturing the semiconductor device according to the present embodiment. [Figure 8] 5A to 5C are schematic cross-sectional views showing a part of the method for manufacturing the semiconductor device according to the present embodiment. [Figure 9] 5A to 5C are schematic cross-sectional views showing a part of the method for manufacturing the semiconductor device according to the present embodiment. [Figure 10] 1 shows electron microscope images of Example 1 and Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values ​​measured by gel permeation chromatography (GPC) in terms of standard polystyrene, and specifically, are values ​​measured based on the method described in the examples.

[0011] In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60."

[0012] As used herein, "energy rays" refers to electromagnetic waves or charged particle beams that have an energy quantum. Examples of energy rays include ultraviolet rays, radioactive rays, and electron beams. Ultraviolet rays can be irradiated using an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a black light, an LED lamp, or the like. Electron beams can be generated by an electron beam accelerator or the like.

[0013] In this specification, "energy ray curable" means a property of being cured by irradiation with energy rays. In addition, in this specification, "thermosetting" means a property of being cured by heating, and "non-curable" means a property of not being cured by heating or irradiation with energy rays.

[0014] In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0015] In this specification, the term "projecting electrode" refers to a projecting electrode of a shape generally used on the circuit formation surface of a semiconductor wafer, for example, and refers to bumps such as ball bumps, columnar electrodes, and the like. In addition, in this specification, the term "member with bumps" means a "semiconductor wafer with bumps" or a "semiconductor chip with bumps."

[0016] In this specification, the "thickness" of an object means the thickness of the entire object, and for example, if the object is made up of multiple layers, it means the total thickness of all layers that make up the object. In this specification, unless otherwise specified, the "thickness" of an object refers to the average thickness measured at five randomly selected points on the object, and can be obtained using a constant pressure thickness gauge in accordance with JIS K 7130.

[0017] In this specification, the term "solid content" or "active ingredient" refers to the components contained in the target composition excluding water and diluting solvents such as organic solvents.

[0018] The mechanism of action described in this specification is speculation and does not limit the mechanism by which the effects of the present invention are achieved.

[0019] In the drawings, for the sake of convenience, in order to make the features of the present invention easier to understand, the essential parts may be shown enlarged, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0020] [Protective film forming film] The film for forming a protective film of this embodiment is a thermosetting film for forming a protective film that is attached to the circuit surface of a wafer, and contains a filler. In an electron microscope image obtained by observing a cross section of at least one of the following samples (1) to (3) in the observation area described below, the maximum diameter of the perfect circle when placed between the fillers is less than 3.0 μm. Sample (1): Uncured protective film-forming film Sample (2): A protective film obtained by thermally curing the protective film-forming film at 130°C for 4 hours without pressure. Sample (3): A protective film obtained by thermally curing the protective film-forming film at 130°C under pressure for 4 hours. <Observation area> When the thickness direction of the samples (1) to (3) is defined as the vertical direction and the direction perpendicular to the thickness direction of the samples (1) to (3) is defined as the horizontal direction, a vertical area of ​​10% of the thickness is excluded from the surface opposite to the surface to be attached to the adherend, and the observation area is the surface formed by a side A of 15 μm from the end of the excluded area toward the surface to be attached to the adherend and a horizontal side B of 33 μm. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area. In this specification, "unpressurized" means a state in which no intentional pressure is being applied, that is, "atmospheric pressure." In addition, in this specification, "pressurization" means a state in which intentional pressure is applied, that is, "pressure higher than atmospheric pressure." The "wafer" is not particularly limited, but is preferably a wafer with protruding electrodes.

[0021] As a result of intensive research to solve the above problem, the inventors have discovered that a film for forming a protective film that satisfies the above parameters can suppress chipping of the wafer when it is cut with a dicing blade. The reason why chipping of the wafer can be suppressed during cutting with a dicing blade is presumed to be as follows. That is, a film for forming a protective film that satisfies the above parameters has excellent uniform dispersion of the filler in the film for forming a protective film. Therefore, the impact during cutting by the dicing blade is easily blocked by the filler, making it difficult for the impact to reach the wafer. Therefore, it is presumed that chipping of the wafer can be suppressed.

[0022] (Diameter of the perfect circle when placed between fillers) In the above parameters, the "diameter of the perfect circle when the perfect circle is placed between the fillers" represents the dispersion state of the filler in the film for forming a protective film, and it can be said that the shorter the diameter, the better the dispersion state of the filler. The present inventors have found that by making the diameter less than 3.0 μm, it is possible to suppress chipping of the wafer when cutting with a dicing blade. Here, from the viewpoint of improving chipping suppression, the diameter is preferably 2.6 μm or less, more preferably 2.2 μm or less, and even more preferably 1.8 μm or less. The diameter is usually 1.0 μm or more. The method for observing at least one cross section of the samples (1) to (3) to obtain an electron microscope image is preferably, but not necessarily limited to, a focused ion beam (FIB). For example, an ICP (Ion Cross Section Polisher) may be used to cut out the observation surface.

[0023] <Configuration of protective film> The protective film forming film is used to form a protective film on a wafer or chip (preferably on the protruding electrode forming surface of a wafer with protruding electrodes or a chip with protruding electrodes). The protective film is soft and has high conformability to uneven surfaces such as the protruding electrode formation surface of the member with protruding electrodes, and therefore exhibits high adhesion to uneven surfaces such as the protruding electrode formation surface of the semiconductor wafer. The film for forming a protective film may be non-curable or curable, but is preferably curable from the viewpoint of improving the protection of the surface on which the protruding electrode is formed (particularly, the protection of the bump neck when the protruding electrode is a bump) and from the viewpoint of forming a protective film with high protection ability, such as excellent impact resistance. The protective film-forming film is preferably thermosetting, that is, hardened by heating.

[0024] The protective film-forming film may be a single layer or may be a multi-layer film of two or more layers. When the protective film-forming film is a multi-layer film, these multi-layers may be the same or different from each other, and the combination of these multi-layers is not particularly limited. However, when the protective film-forming film has multiple layers, it is preferable that at least one layer satisfies the above parameters.

[0025] The thickness of the protective film-forming film is not particularly limited, but is preferably 5 to 70 μm, more preferably 10 to 60 μm, and even more preferably 15 to 45 μm. When the thickness of the protective film-forming film is equal to or greater than the lower limit, it is easy to produce a sheet with high in-plane uniformity, and it tends to be possible to form a protective film with higher protective ability. Also, when the thickness of the protective film-forming film is equal to or less than the upper limit, it tends to prevent the protective film from becoming excessively thick, and it is easy to prevent an increase in residue on the top of the projecting electrode. The thickness of the protective film-forming film can be adjusted based on information such as the relationship between the thickness of the protective film-forming film and the thickness of the protective film formed by hardening the protective film-forming film, and the height of the protruding electrodes of the member with protruding electrodes to be used. The curable resin film (x) as a protective film-forming film will be described in detail below.

[0026] (Curable resin film (x)) The curable resin film (x) may be non-curable or curable, but is preferably curable from the viewpoint of improving the protection of the surface on which the projecting electrodes are formed (particularly, the protection of the bump neck when the projecting electrodes are bumps) and from the viewpoint of forming a protective film with high protection ability, such as excellent impact resistance. The curable resin film (x) is preferably thermosetting, that is, cured by heating. The thermosetting resin film (x1) will be described below.

[0027] (Thermosetting resin film (x1)) The thermosetting resin film (x1) of this embodiment forms a cured resin film by being cured by heating. The thermosetting resin film of this embodiment contains a polymer component (A) and a thermosetting component (B). The thermosetting resin film (x1) of this embodiment is formed, for example, from a thermosetting resin composition (x1-1) containing the polymer component (A) and the thermosetting component (B). The polymer component (A) is a component that can be considered to be formed by a polymerization reaction of a polymerizable compound. The thermosetting component (B) is a component that can undergo a curing (polymerization) reaction when triggered by heat. The curing (polymerization) reaction also includes a polycondensation reaction.

[0028] -Polymer component (A)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) contain a polymer component (A). The polymer component (A) is a polymer compound for imparting film-forming properties, flexibility, etc. to the thermosetting resin film (x1). The polymer component (A) may be used alone or in combination of two or more. When two or more polymer components (A) are used in combination, the combination and ratio thereof can be selected arbitrarily.

[0029] Examples of the polymer component (A) include acrylic resins, polyarylate resins, acetal resins, polyesters, urethane resins (resins having urethane bonds), acrylic urethane resins, silicone resins (resins having siloxane bonds), rubber resins (resins having a rubber structure), phenoxy resins, and thermosetting polyimides. Among these, acrylic resins, polyarylate resins, and acetal resins are preferred, and acetal resins are more preferred.

[0030] Examples of the acrylic resin include known acrylic polymers. The weight average molecular weight (Mw) of the acrylic resin is preferably 10,000 to 2,000,000, more preferably 300,000 to 1,500,000, and even more preferably 500,000 to 1,000,000. When the weight-average molecular weight of the acrylic resin is equal to or greater than the lower limit, the shape stability (stability over time during storage) of the thermosetting resin film (x1) is easily improved. Furthermore, when the weight-average molecular weight of the acrylic resin is equal to or less than the upper limit, the thermosetting resin film (x1) is easily conformable to the uneven surface of the adherend, which makes it easier to suppress the generation of voids between the adherend and the thermosetting resin film. Therefore, the coverage of the surface of the semiconductor wafer on which the protruding electrodes are formed is improved, and the ability to fill grooves is also easily improved.

[0031] The glass transition temperature (Tg) of the acrylic resin is preferably -60 to 70°C, more preferably -40 to 50°C, and even more preferably -30 to 30°C, from the viewpoint of the application and handling properties of the thermosetting resin film (x1).

[0032] Examples of acrylic resins include polymers of one or more (meth)acrylic acid esters; copolymers of two or more monomers selected from (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

[0033] Examples of the (meth)acrylic acid ester constituting the acrylic resin include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and (meth) (meth)acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester has a chain structure and has 1 to 18 carbon atoms, such as isononyl acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, and octadecyl (meth)acrylate (stearyl (meth)acrylate); (meth)acrylic acid cycloalkyl esters such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; (Meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate; (Meth)acrylic acid cycloalkenyl esters such as (meth)acrylic acid dicyclopentenyl ester; (Meth)acrylic acid cycloalkenyloxyalkyl esters such as (meth)acrylic acid dicyclopentenyloxyethyl ester; (Meth)acrylic acid imide; glycidyl group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate; hydroxyl group-containing (meth)acrylic acid esters such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; Examples include substituted amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate. As used herein, the term "substituted amino group" refers to a group in which one or two hydrogen atoms of an amino group have been substituted with a group other than a hydrogen atom. Among these, from the viewpoint of the film-forming properties of the thermosetting resin film (x1) and the adhesiveness of the thermosetting resin film (x1) to the protective film-forming surface of a semiconductor chip, it is preferable that the alkyl group constituting the alkyl ester is a copolymer of a (meth)acrylic acid alkyl ester, a glycidyl group-containing (meth)acrylic acid ester, and a hydroxyl group-containing (meth)acrylic acid ester, each of which has a chain structure containing 1 to 18 carbon atoms; it is more preferable that the alkyl group constituting the alkyl ester is a copolymer of a (meth)acrylic acid alkyl ester, a glycidyl group-containing (meth)acrylic acid ester, and a hydroxyl group-containing (meth)acrylic acid ester, each of which has a chain structure containing 1 to 4 carbon atoms; and it is even more preferable that the copolymer is a copolymer of a combination of butyl acrylate, methyl acrylate, glycidyl acrylate, and 2-hydroxyethyl acrylate.

[0034] The acrylic resin may be, for example, a copolymer of one or more monomers selected from (meth)acrylic acid ester, (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylolacrylamide, and the like.

[0035] The monomers constituting the acrylic resin may be used alone or in combination of two or more. When the acrylic resin is composed of two or more monomers, the combination and ratio thereof can be selected arbitrarily.

[0036] The polyarylate resin in the polymer component (A) may be any known resin, such as a resin having a basic structure obtained by polycondensation of a dihydric phenol with a dibasic acid such as phthalic acid or carboxylic acid. Among these, a polycondensate of bisphenol A with phthalic acid, poly(4,4'-isopropylidenediphenylene terephthalate / isophthalate) copolymer, or a derivative thereof is preferred.

[0037] The acetal resin in the polymer component (A) may be any known resin. Of these, preferred acetal resins include, for example, polyvinyl formal and polyvinyl butyral, with polyvinyl butyral being more preferred. Examples of polyvinyl butyral include those having structural units represented by the following formulas (i)-1, (i)-2, and (i)-3.

[0038] [ka]

[0039] (In the formula, l, m, and n each independently represent an integer of 1 or more.)

[0040] The weight-average molecular weight (Mw) of the polyvinyl acetal is preferably 5,000 to 200,000, more preferably 8,000 to 100,000. When the weight-average molecular weight of the polyvinyl acetal is equal to or greater than the above-mentioned lower limit, the shape stability (stability over time during storage) of the thermosetting resin film (x1) is easily improved. Furthermore, when the weight-average molecular weight of the polyvinyl acetal is equal to or less than the above-mentioned upper limit, the thermosetting resin film (x1) is easily conformable to the irregular surface of the adherend, which makes it easier to suppress the occurrence of voids, for example, between the adherend and the thermosetting resin film (x1). Therefore, the coverage of the surface of the semiconductor wafer on which the protruding electrodes are formed is improved, and the embedding of grooves is also easily improved.

[0041] The glass transition temperature (Tg) of the polyvinyl acetal is preferably 40 to 80°C, more preferably 50 to 70°C, from the viewpoint of the film-forming properties of the thermosetting resin film (x1) and the exposing properties of the top of the projecting electrode. Here, in this specification, the term "exposure property of the top of the protruding electrode" refers to the ability of the protruding electrode to penetrate the thermosetting resin film (x1) for forming a protective film when the thermosetting resin film (x1) is attached to the wafer with the protruding electrode, and is also referred to as the penetration property of the top of the protruding electrode.

[0042] The ratio of the three or more monomers constituting the polyvinyl acetal can be selected arbitrarily.

[0043] The content of the polymer component (A) is preferably 2 to 30 mass% based on the total amount of the active ingredients of the thermosetting resin composition (x1-1), more preferably 3 to 25 mass%, even more preferably 3 to 15 mass%, even more preferably 3 to 10 mass%, and even more preferably 3 to 8 mass%. In particular, by setting the content of the polymer component (A) to 8 mass% or less, the proportion of the thermosetting component described below can be relatively increased, making it easier to obtain a film for forming a protective film that satisfies the above parameters.

[0044] The polymer component (A) may also correspond to the thermosetting component (B). In this embodiment, when the thermosetting resin composition (x1-1) contains components that correspond to both the polymer component (A) and the thermosetting component (B), the thermosetting resin composition (x1-1) is considered to contain both the polymer component (A) and the thermosetting component (B).

[0045] -Thermosetting component (B)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) contain a thermosetting component (B). The thermosetting component (B) is a component for curing the thermosetting resin film (x1) to form a hard cured resin film. The thermosetting component (B) may be used singly or in combination of two or more. When two or more thermosetting components (B) are used, the combination and ratio thereof can be selected arbitrarily.

[0046] Examples of the thermosetting component (B) include epoxy-based thermosetting resins, thermosetting polyimides, polyurethanes, unsaturated polyesters, and silicone resins. Among these, epoxy-based thermosetting resins are preferred. When the thermosetting component (B) is an epoxy-based thermosetting resin, the protective properties of the cured resin film and the protruding properties of the tops of the projecting electrodes can be improved, and warping of the cured resin film can be suppressed.

[0047] The epoxy thermosetting resin is composed of an epoxy resin (B1) and a thermosetting agent (B2). The epoxy thermosetting resin may be used alone or in combination of two or more. When two or more epoxy thermosetting resins are used, the combination and ratio thereof can be selected arbitrarily.

[0048] -Epoxy resin (B1)- The epoxy resin (B1) is not particularly limited, but from the viewpoint of making it easier to exhibit the effects of the present invention, it is preferable to use a combination of an epoxy resin that is solid at room temperature (hereinafter also referred to as a solid epoxy resin) and an epoxy resin that is liquid at room temperature (hereinafter also referred to as a liquid epoxy resin). In this specification, "room temperature" refers to 5 to 35°C, preferably 15 to 25°C.

[0049] The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature, and examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac type epoxy resins, glycidyl ester type epoxy resins, biphenyl type epoxy resins, phenylene skeleton type epoxy resins, etc. Among these, bisphenol A type epoxy resins are preferred. The liquid epoxy resin may be used alone or in combination of two or more. When two or more liquid epoxy resins are used, the combination and ratio thereof can be selected arbitrarily.

[0050] The epoxy equivalent of the liquid epoxy resin is preferably 200 to 600 g / eq, more preferably 250 to 550 g / eq, and even more preferably 300 to 500 g / eq. The epoxy equivalent in this embodiment can be measured in accordance with JIS K 7236:2009.

[0051] The solid epoxy resin is not particularly limited as long as it is solid at room temperature, and examples thereof include biphenyl-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, orthocresol novolac epoxy resins, dicyclopentadiene-type epoxy resins, naphthalene-type epoxy resins, anthracene-type epoxy resins, fluorene-type epoxy resins, etc. Among these, naphthalene-type epoxy resins, dicyclopentadiene-type epoxy resins, and fluorene-type epoxy resins are preferred, and naphthalene-type epoxy resins and dicyclopentadiene-type epoxy resins are more preferred. The solid epoxy resin may be used alone or in combination of two or more. When two or more solid epoxy resins are used, the combination and ratio thereof can be selected arbitrarily.

[0052] The epoxy equivalent of the solid epoxy resin is preferably 150 to 450 g / eq, more preferably 150 to 400 g / eq.

[0053] The ratio of the content of the liquid epoxy resin (xe) to the content of the solid epoxy resin (ye) [(xe) / (ye)] is preferably 0.01 to 10.0 by mass, more preferably 0.02 to 8.0, and even more preferably 0.03 to 6.0. When the ratio [(xe) / (ye)] is within the above range, the generation of cutting waste and the like can be suppressed when cutting the cured resin film with a dicing blade, and processability can be easily improved.

[0054] The number average molecular weight of the epoxy resin (B1) is not particularly limited, but from the viewpoints of the curability of the thermosetting resin film and the strength and heat resistance of the cured resin film after curing, it is preferably 300 to 30,000, more preferably 400 to 10,000, and even more preferably 500 to 3,000.

[0055] -Thermal hardener (B2)- The heat curing agent (B2) functions as a curing agent for the epoxy resin (B1). The thermosetting agent (B2) may be, for example, a compound having two or more functional groups per molecule that can react with an epoxy group. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group, a carboxyl group, and an anhydride group of an acid group. A phenolic hydroxyl group, an amino group, or an anhydride group of an acid group is preferred, and a phenolic hydroxyl group or an amino group is more preferred.

[0056] Among the heat curing agents (B2), examples of phenolic curing agents having a phenolic hydroxyl group include polyfunctional phenolic resins, biphenols, novolac-type phenolic resins, dicyclopentadiene-based phenolic resins, and aralkyl phenolic resins. Among the heat curing agents (B2), examples of amine-based curing agents having an amino group include dicyandiamide (hereinafter sometimes abbreviated as "DICY"). Among these, phenolic curing agents having a phenolic hydroxyl group are preferred, and novolac-type phenolic resins are more preferred.

[0057] Of the thermosetting agents (B2), for example, the number average molecular weight of resin components such as polyfunctional phenol resins, novolac-type phenol resins, dicyclopentadiene-based phenol resins, and aralkyl phenol resins is preferably 300 to 30,000, more preferably 400 to 10,000, and even more preferably 500 to 3,000. Of the thermosetting agent (B2), the molecular weight of the non-resin component such as biphenol or dicyandiamide is not particularly limited, but is preferably 60 to 500, for example.

[0058] The heat curing agent (B2) may be used singly or in combination of two or more. When two or more types of heat curing agents (B2) are used, the combination and ratio thereof can be selected arbitrarily.

[0059] In the thermosetting resin composition (x1-1), the content of the thermosetting agent (B2) is preferably 0.010 to 200 parts by mass, more preferably 0.020 to 150 parts by mass, even more preferably 0.050 to 100 parts by mass, and even more preferably 0.10 to 77 parts by mass, per 100 parts by mass of the epoxy resin (B1). When the content of the thermosetting agent (B2) is equal to or greater than the above-mentioned lower limit, curing of the thermosetting resin film (x1) proceeds more easily. Furthermore, when the content of the thermosetting agent (B2) is equal to or less than the above-mentioned upper limit, the moisture absorption rate of the thermosetting resin film is reduced, and the reliability of the package obtained using the thermosetting resin film (x1) is further improved.

[0060] In the thermosetting resin composition (x1-1), the content of the thermosetting component (B) (total content of the epoxy resin (B1) and the thermosetting agent (B2)) is preferably 200 to 10,000 parts by mass, more preferably 400 to 5,000 parts by mass, even more preferably 600 to 4,000 parts by mass, even more preferably 800 to 3,000 parts by mass, and even more preferably 1,000 to 2,000 parts by mass, per 100 parts by mass of the polymer component (A), from the viewpoint of enhancing the protective properties of the cured resin film. In particular, by making the content of the thermosetting component (B) 800 parts by mass or more, a film for forming a protective film that satisfies the above parameters is easily obtained.

[0061] -Curing accelerator (C)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) may contain a curing accelerator (C). The curing accelerator (C) is a component for adjusting the curing rate of the thermosetting resin composition (x1-1). Preferred examples of the curing accelerator (C) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines (phosphines in which one or more hydrogen atoms are substituted with organic groups) such as tributylphosphine, diphenylphosphine, and triphenylphosphine; and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. Among these, imidazoles are preferred, and 2-phenyl-4,5-dihydroxymethylimidazole is more preferred, from the viewpoint of making it easier to exhibit the effects of the present invention.

[0062] The curing accelerator (C) may be used singly or in combination of two or more. When two or more curing accelerators (C) are used, the combination and ratio thereof can be selected arbitrarily.

[0063] When a curing accelerator (C) is used in the thermosetting resin composition (x1-1), the content of the curing accelerator (C) is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the thermosetting component (B). When the content of the curing accelerator (C) is equal to or greater than the above-mentioned lower limit, the effect of using the curing accelerator (C) is more pronounced. Furthermore, when the content of the curing accelerator (C) is equal to or less than the above-mentioned upper limit, for example, the effect of suppressing the highly polar curing accelerator (C) from migrating and segregating to the adhesive interface with the adherend in the thermosetting resin film (x1) under high temperature and high humidity conditions is enhanced, thereby further improving the reliability of the package obtained using the thermosetting resin film (x1).

[0064] -Filling material (D)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) contain a filler (D). By containing the filler (D) and satisfying the above parameters, a film for forming a protective film having excellent chipping suppression properties can be obtained. Furthermore, by including the filler (D), it becomes easier to adjust the thermal expansion coefficient of the cured resin film obtained by curing the thermosetting resin film (x1) to an appropriate range, and the reliability of the package obtained using the thermosetting resin film (x1) is further improved. Furthermore, by including the filler (D) in the thermosetting resin film (x1), it is possible to reduce the moisture absorption rate of the cured resin film and improve the heat dissipation properties.

[0065] The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler or an organic / inorganic hybrid filler. Examples of preferred inorganic fillers include powders of silica, talc, calcium carbonate, boron nitride, and the like; beads of these inorganic fillers that have been spherically formed; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; and glass fibers. Examples of preferred organic / inorganic hybrid fillers include fillers based on mixed components such as silica-acrylic composite particles (e.g., Soliostar, manufactured by Nippon Shokubai); and composite fillers incorporating inorganic fine particles with an organic material. Among these, inorganic fillers are preferred, and the inorganic filler is preferably silica. Furthermore, from the viewpoint of improving the dispersibility of the filler (D) in the protective film-forming film and making it easier to satisfy the above parameters, the filler (D) is preferably silica modified with an epoxy group.

[0066] The filler (D) may be used alone or in combination of two or more kinds. When two or more types of filler (D) are used, the combination and ratio thereof can be selected arbitrarily.

[0067] The content of the filler (D) is preferably 5 to 50 mass%, more preferably 7 to 40 mass%, and even more preferably 10 to 30 mass%, based on the total amount of active ingredients of the thermosetting resin composition, from the viewpoint of suppressing peeling of the cured resin film from the chip due to thermal expansion and thermal contraction.

[0068] The average particle size of the filler (D) is preferably 500 nm or less, more preferably from 5 to 300 nm, and particularly preferably from 10 to 100 nm. In this specification, the particle size of the filler (D) refers to the arithmetic mean particle size obtained by measuring the particle sizes of multiple randomly selected primary particles of the filler (D) observed under an electron microscope and calculating the average value.

[0069] -Energy ray curable resin (E)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) may contain an energy ray-curable resin (E). The thermosetting resin film (x1) contains the energy ray-curable resin (E), and thus its properties can be changed by irradiation with energy rays.

[0070] The energy ray curable resin (E) is obtained by polymerizing (curing) an energy ray curable compound. Examples of the energy ray curable compound include compounds having at least one polymerizable double bond in the molecule, and acrylate compounds having a (meth)acryloyl group are preferred.

[0071] Examples of acrylate compounds include chain acrylates such as trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. Examples of the polyalkylene glycol (meth)acrylate include aliphatic skeleton-containing (meth)acrylates; alicyclic skeleton-containing (meth)acrylates such as dicyclopentanyl di(meth)acrylate; polyalkylene glycol (meth)acrylates such as polyethylene glycol di(meth)acrylate; oligoester (meth)acrylates; urethane (meth)acrylate oligomers; epoxy-modified (meth)acrylates; polyether (meth)acrylates other than the above polyalkylene glycol (meth)acrylates; and itaconic acid oligomers.

[0072] The weight average molecular weight of the energy ray-curable compound is preferably from 100 to 30,000, and more preferably from 300 to 10,000.

[0073] The energy ray-curable compound used for polymerization may be used alone or in combination of two or more. When two or more energy ray-curable compounds are used for polymerization, the combination and ratio thereof can be selected arbitrarily.

[0074] When the energy ray curable resin (E) is used, the content of the energy ray curable resin (E) is preferably 1 to 95 mass%, more preferably 5 to 90 mass%, and even more preferably 10 to 85 mass%, based on the total amount of the active ingredients of the thermosetting resin composition (x1-1).

[0075] -Photopolymerization initiator (F)- When the thermosetting resin film (x1) and the thermosetting resin composition (x1-1) contain an energy ray-curable resin (E), the thermosetting resin film (x1) and the thermosetting resin composition (x1-1) may contain a photopolymerization initiator (F) in order to efficiently proceed with the polymerization reaction of the energy ray-curable resin (E).

[0076] Examples of the photopolymerization initiator (F) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, 1,2-diphenylmethane, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-chloroanthraquinone.

[0077] The photopolymerization initiator (F) may be used singly or in combination of two or more. When two or more photopolymerization initiators (F) are used, the combination and ratio thereof can be selected arbitrarily.

[0078] In the thermosetting resin composition (x1-1), the content of the photopolymerization initiator (F) is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 2 to 5 parts by mass, relative to 100 parts by mass of the content of the energy ray-curable resin (E).

[0079] -Additive (G)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) may contain an additive (G) within the range that does not impair the effects of the present invention. The additive (G) may be a known additive and may be selected arbitrarily depending on the purpose, and is not particularly limited. Preferred examples of the additive (G) include coupling agents, crosslinking agents, surfactants, plasticizers, antistatic agents, antioxidants, leveling agents, and gettering agents. Among these,

[0080] The additive (G) may be used singly or in combination of two or more. When two or more additives (G) are used, the combination and ratio thereof can be selected arbitrarily. The content of the additive (G) is not particularly limited and may be appropriately selected depending on the purpose.

[0081] -solvent- The thermosetting resin composition (x1-1) preferably further contains a solvent. The thermosetting resin composition (x1-1) containing a solvent has good handleability. The solvent is not particularly limited, but preferred examples include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone. The solvent may be used alone or in combination of two or more. When two or more solvents are used, the combination and ratio thereof can be selected arbitrarily. The solvent is preferably methyl ethyl ketone or the like, since it allows the components contained in the thermosetting resin composition (x1-1) to be mixed more uniformly.

[0082] -Method for preparing thermosetting resin composition (x1-1)- The thermosetting resin composition (x1-1) is prepared by blending the components that constitute it. The order of addition of the components when blending is not particularly limited, and two or more components may be added simultaneously. When a solvent is used, the solvent may be mixed with any of the other components to pre-dilute the components, or the solvent may be mixed with any of the other components without pre-diluting them. The method for mixing the components during blending is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or stirring blades, a method of mixing using a mixer, or a method of mixing by adding ultrasound. The temperature and time for adding and mixing each component are not particularly limited as long as the components do not deteriorate, and may be adjusted appropriately. A temperature of 15 to 30°C is preferred.

[0083] (Preparation of protective film) The film for forming a protective film of this embodiment can be produced, for example, by applying the composition for forming a protective film of this embodiment to the surface on which the film is to be formed, and drying it as necessary. The protective film-forming composition may be applied by a known method, such as a method using various coaters such as an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Mayer bar coater, or kiss coater. The drying conditions after applying the protective film-forming composition are not particularly limited, but may be, for example, a drying temperature of 70 to 130° C. and a drying time of 10 seconds to 5 minutes.

[0084] (Requirement (I)) The film for forming a protective film of this embodiment preferably satisfies the following requirement (I) from the viewpoint of filling and conforming to recesses in a wafer provided for a dicing step. Requirement (I): A test piece of the thermosetting resin film having a diameter of 25 mm and a thickness of 1 mm is strained at a temperature of 90°C and a frequency of 1 Hz, and the storage modulus of the test piece is measured. When the storage modulus of the test piece when the strain of the test piece is 1% is defined as Gc1 and the storage modulus of the test piece when the strain of the test piece is 300% is defined as Gc300, the value of X calculated by the following formula (i) is 10 or more and less than 10,000. X=Gc1 / Gc300...Formula (i)

[0085] The upper limit of the X value specified in the above requirement (I) is, from the viewpoint of forming a protective film having excellent coating properties, preferably 5,000 or less, more preferably 2,000 or less, even more preferably 1,000 or less, still more preferably 500 or less, even more preferably 400 or less, still more preferably 300 or less, even more preferably 100 or less, and particularly preferably 70 or less. Furthermore, from the viewpoint of improving the filling and conformability to recesses in a wafer provided for a dicing step, the lower limit of the X value specified in the above requirement (I) is preferably 19 or more, more preferably 20 or more, even more preferably 30 or more, and still more preferably 40 or more.

[0086] In the film for forming a protective film, Gc1 is not particularly limited as long as the X value defined in the requirement (I) is 10 or more and less than 10,000. However, from the viewpoint of making it easier to form a protective film with excellent coverage, Gc1 is set to 1×10 2 ~1×10 6 Pa is preferred, and 2×10 3 ~7×105 Pa is more preferable, and 3×10 3 ~5×10 5 Pa is more preferred.

[0087] In the above-mentioned film for forming a protective film, Gc300 is not particularly limited as long as the X value is 10 or more and less than 10,000. However, from the viewpoint of improving the embeddability of the thermosetting resin film into the bump bases and into the grooves of the semiconductor chip fabrication wafer after the bumps penetrate the thermosetting resin film, Gc300 is preferably 10 to 15,000 Pa, more preferably 30 to 10,000 Pa, and even more preferably 60 to 5,000 Pa.

[0088] In order to adjust the X value defined by the above requirement (I), it is necessary to adjust the storage modulus of the thermosetting resin film (x1). However, the storage modulus of the thermosetting resin film (x1) is not limited to Gc1 and Gc300, and can be easily adjusted by adjusting one or both of the types and contents of the components contained in the thermosetting resin film (x1). To achieve this, it is sufficient to adjust one or both of the types and contents of the components contained in the composition for forming the thermosetting resin film (x1). For example, the storage modulus of the thermosetting resin film (x1) can be easily adjusted by adjusting one or both of the types and contents of the main components, such as the polymer component (A) and the filler (D), and adjusting one or both of the types and contents of one or more additives (G) selected from the group consisting of a rheology control agent, a surfactant, and a silicone oil. For example, by increasing the content of one or both of the filler (D) and the additive (G) in the thermosetting resin film (x1), it becomes easier to adjust Gc1 to a larger value, and as a result, it becomes easier to adjust the X value to a larger value.

[0089] (Requirement (II)) From the viewpoint of making it easier to suppress chipping, the film for forming a protective film of the present embodiment preferably satisfies the following requirement (II). Requirement (II): The glass transition temperature of the protective film is 40°C or higher. Here, from the viewpoint of making it easier to suppress chipping, the glass transition temperature of the protective film-forming film is preferably 60°C or higher, more preferably 80°C or higher, and even more preferably 100°C or higher. The glass transition temperature of the film for forming a protective film means a value measured by the method described in the examples below.

[0090] [Configuration of composite sheet for forming protective film] The film for forming a protective film in this embodiment may be a single-layer film or may be formed on the release-treated surface of a release film, but from the standpoint of improving handleability, etc., it is preferable that it is a composite sheet for forming a protective film in which other layers are further laminated. Hereinafter, the first to fifth embodiments will be described as examples of the configuration of the composite sheet for forming a protective film of the present embodiment. However, the configuration examples of the composite sheet for forming a protective film of the present embodiment are not limited to the first to fifth embodiments. For example, the first to fifth embodiments may of course further include other layers as long as the effects of the present invention are not significantly impaired.

[0091] (First aspect) A first aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. 1 has a substrate 10 and a protective film-forming film 12. Although not shown, a release film or a tape having an adhesive may be provided on the surface of the protective film-forming film 12 opposite to the substrate 10.

[0092] (Second aspect) A second aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. 2 has a buffer layer 11 and a protective film-forming film 12. Although not shown, a release film or a tape having an adhesive may be provided on the surface of the protective film-forming film 12 opposite to the buffer layer 11.

[0093] (Third aspect) A third aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. 3 has, in this order, a substrate 10, a buffer layer 11, and a protective film-forming film 12. Although not shown, a release film or a tape having an adhesive may be provided on the surface of the protective film-forming film 12 opposite to the buffer layer 11.

[0094] (Fourth aspect) A fourth aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. The composite sheet for forming a protective film of the fourth embodiment has an intermediate release layer between the buffer layer and the protective film-forming film in the composite sheet for forming a protective film of the second embodiment. That is, the composite sheet for forming a protective film 1d of the third embodiment has an intermediate release layer 13 between the buffer layer 11 and the protective film-forming film 12, as shown in Fig. 4. Although not shown, the surface of the protective film-forming film 12 opposite to the intermediate release layer 13 may be provided with a release film or a tape having an adhesive.

[0095] (Fifth aspect) A fifth aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. The composite sheet for forming a protective film of the fifth embodiment has an intermediate release layer between the buffer layer and the film for forming a protective film in the composite sheet for forming a protective film of the third embodiment. That is, as shown in Fig. 5, the composite sheet for forming a protective film 1e of the fifth embodiment has a substrate 10, a buffer layer 11 laminated on one surface 10a of the substrate 10, an intermediate release layer 13 laminated on the surface of the buffer layer 11 opposite the substrate 10, and a film for forming a protective film 12 laminated on the surface of the intermediate release layer 13 opposite the buffer layer 11. Although not shown, a release film or a tape having an adhesive may be provided on the surface of the film for forming a protective film 12 opposite the intermediate release layer 13.

[0096] <Buffer layer> The buffer layer is a layer that has a buffering effect against forces applied to the buffer layer and a layer directly or indirectly adjacent thereto. Here, the "layer directly or indirectly adjacent to the buffer layer" mainly refers to the protective film of this embodiment.

[0097] The buffer layer may be a single layer or a plurality of layers, two or more of which may be the same or different, and the combination of these layers is not particularly limited.

[0098] The thickness of the buffer layer can be adjusted appropriately depending on the height of the projecting electrode to be protected. From the viewpoint of making it easier to achieve the effects of the present invention even for projecting electrodes with a relatively high height, the thickness is preferably 150 to 1,000 μm, more preferably 180 to 800 μm, and even more preferably 200 to 600 μm.

[0099] (Storage modulus (G') of buffer layer at 80°C) In the composite sheet for forming a protective film of this embodiment, the storage modulus (G') of the buffer layer at 80°C is preferably 0.08 MPa or more. When the storage modulus (G') of the buffer layer at 80°C is 0.08 MPa or more, it is easy to ensure the protruding electrode penetration of the protective film-forming film, and it is easy to ensure the connection reliability between the chip with protruding electrodes and the substrate. Here, from the viewpoint of more easily ensuring the projecting electrode penetration ability of the protective film-forming film, the storage modulus (G') of the buffer layer at 80°C is more preferably 0.10 MPa or more, even more preferably 0.12 MPa or more, even more preferably 0.14 MPa or more, and even more preferably 0.16 MPa or more. In addition, the storage modulus (G') of the buffer layer at 80°C is preferably 0.4 MPa or less, from the viewpoint of making it easier to adjust the loss tangent (tanδ) of the buffer layer at 80°C described later to 1.02 or more, and making it easier to ensure the embeddability of the projecting electrode in the protective film-forming film. The storage modulus (G') of the buffer layer at 80°C is a value measured by the method described in the examples below.

[0100] (loss tangent (tanδ) of buffer layer at 80°C) In the composite sheet for forming a protective film of this embodiment, the loss tangent (tan δ) of the buffer layer at 80° C. is preferably 1.02 or more. When the loss tangent (tan δ) of the buffer layer at 80° C. is 1.02 or more, the embedding ability of the protective film-forming film into the projecting electrodes (the penetration ability of the protective film-forming film into the periphery of the base of the projecting electrodes) is easily ensured. Here, from the viewpoint of more easily ensuring the embedding ability of the projecting electrode in the protective film-forming film, the loss tangent (tanδ) of the buffer layer at 80°C is more preferably 1.05 or more, even more preferably 1.08 or more, even more preferably 1.12 or more, and even more preferably 1.16 or more. In addition, the loss tangent (tanδ) of the buffer layer at 80°C is preferably 2.00 or less, from the viewpoint of making it easier to adjust the storage modulus (G') of the buffer layer at 80°C to 0.08 or more and making it easier to ensure the projecting electrode penetration ability of the protective film-forming film. The loss tangent (tan δ) of the buffer layer at 80° C. means a value measured by the method described in the examples below.

[0101] In this embodiment, the storage modulus (G') at 80° C. and the loss tangent (tan δ) at 80° C. of the buffer layer can be adjusted appropriately by adjusting the composition of the buffer layer, etc. The buffer layer will be described in detail below, taking into consideration the method for adjusting the storage modulus (G') at 80°C and the loss tangent (tan δ) at 80°C of the buffer layer.

[0102] (urethane (meth)acrylate) Urethane (meth)acrylate is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of polymerizing upon irradiation with energy rays. The use of urethane (meth)acrylate imparts flexibility to the buffer layer, making it easier to adjust the storage modulus (G') at 80°C and loss tangent (tanδ) at 80°C of the buffer layer within the above ranges. The urethane (meth)acrylate may be monofunctional or polyfunctional. In this embodiment, polyfunctional urethane (meth)acrylate is preferred, and from the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer to the above ranges, bifunctional urethane (meth)acrylate is preferred. The urethane (meth)acrylate may be an oligomer, a polymer, or a mixture thereof. In this embodiment, a urethane (meth)acrylate oligomer is preferred. The urethane (meth)acrylate can be obtained, for example, by reacting a polyol compound with a polyvalent isocyanate compound to obtain a terminal isocyanate urethane prepolymer, and then reacting the resulting prepolymer with a (meth)acrylate having a hydroxy group. The urethane (meth)acrylate may be used alone or in combination of two or more. The content of the urethane (meth)acrylate in the buffer layer composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, from the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer within the above ranges. The content of the urethane (meth)acrylate in the intermediate layer composition is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 50% by mass or less.

[0103] (Polymerizable monomer) The polymerizable monomer is preferably a polymerizable compound other than the above-mentioned urethane (meth)acrylate, which is polymerizable with other components upon irradiation with energy rays. Specifically, the polymerizable monomer is preferably a compound having at least one (meth)acryloyl group. Examples of the polymerizable monomer include (meth)acrylates having an alkyl group having 1 to 30 carbon atoms; (meth)acrylates having a functional group such as a hydroxyl group, an amide group, an amino group, or an epoxy group; (meth)acrylates having an alicyclic structure; (meth)acrylates having an aromatic structure; (meth)acrylates having a heterocyclic structure; and vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Examples of (meth)acrylates having an alkyl group having 1 to 30 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, and eicosyl (meth)acrylate. Examples of the (meth)acrylate having a functional group include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, and N-methylol (meth)acrylamide. Amide group-containing compounds such as N-methylolpropane(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide; amino group-containing (meth)acrylates such as primary amino group-containing (meth)acrylates, secondary amino group-containing (meth)acrylates, and tertiary amino group-containing (meth)acrylates; and epoxy group-containing (meth)acrylates such as glycidyl(meth)acrylate, methylglycidyl(meth)acrylate, and allyl glycidyl ether. Examples of (meth)acrylates having an alicyclic structure include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, and adamantane (meth)acrylate. Examples of the (meth)acrylate having an aromatic structure include phenylhydroxypropyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. Examples of the (meth)acrylate having a heterocyclic structure include tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate. In this embodiment, the polymerizable monomer preferably includes a (meth)acrylate having an alkyl group with 1 to 30 carbon atoms and a (meth)acrylate having an alicyclic structure. From the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer to the above ranges, a (meth)acrylate having an alkyl group with 4 to 14 carbon atoms is preferred, and as the (meth)acrylate having an alicyclic structure, isobornyl (meth)acrylate and trimethylcyclohexyl (meth)acrylate are preferred. When a crosslinking agent is contained in the buffer layer-forming composition, a (meth)acrylate having a functional group that can react with the crosslinking agent is not preferred. This is because the crosslinked structure formed by the crosslinking reaction may increase the residual stress in the buffer layer. For example, a buffer layer-forming composition containing a polyisocyanate-based crosslinking agent and a (meth)acrylate having a hydroxyl group is not preferred. The content of the polymerizable monomer in the buffer layer-forming composition is preferably 20% by mass or more, and more preferably 30% by mass or more, from the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer within the above ranges. The content of the polymerizable monomer in the buffer layer-forming composition is preferably 80% by mass or less, and more preferably 70% by mass or less. Furthermore, the mass ratio of the urethane (meth)acrylate to the polymerizable monomer (urethane (meth)acrylate / polymerizable monomer) in a total of 100 parts by mass of the urethane (meth)acrylate and the polymerizable monomer is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30, from the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer within the above ranges.

[0104] (Photopolymerization initiator) When the buffer layer-forming composition contains the urethane (meth)acrylate and polymerizable monomer, it preferably contains a photopolymerization initiator, which ensures that polymerization proceeds reliably and makes it easier to adjust the storage modulus (G') at 80°C and loss tangent (tanδ) at 80°C of the buffer layer to fall within the above-mentioned ranges. Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, as well as photosensitizers such as amines and quinones. Specific examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and 2,2-dimethoxy-1,2-diphenylethan-1-one. These photopolymerization initiators may be used alone or in combination of two or more. The amount of the photopolymerization initiator is preferably 0.05 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the total of the urethane (meth)acrylate and the polymerizable monomer.

[0105] (chain transfer agent) The buffer layer-forming composition preferably contains a chain transfer agent. The chain transfer agent can initiate a chain transfer reaction and adjust the progress of the curing reaction of the buffer layer-forming composition. The inclusion of a chain transfer agent allows components with short molecular chains to remain relatively even after curing, resulting in a polymer with a relatively flexible structure after curing. As a result, the storage modulus (G') at 80°C and loss tangent (tanδ) at 80°C of the buffer layer can be easily adjusted to fall within the above-mentioned ranges. Examples of the chain transfer agent include thiol group-containing compounds, such as nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazine thiol, triazine dithiol, triazine trithiol, 1,2,3-propane trithiol, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetraki ... Examples of the chain transfer agent include thritol tetrakis thioglucarate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione. The chain transfer agent may be used alone or in combination of two or more. The amount of the chain transfer agent is preferably 1.0 parts by mass or more and 2.5 parts by mass or less, more preferably 1.2 parts by mass or more and 2.0 parts by mass or less, and even more preferably 1.3 parts by mass or more and 1.8 parts by mass or less, relative to 100 parts by mass of the total of the urethane (meth)acrylate and the polymerizable monomer, from the viewpoint of easily adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer within the above ranges.

[0106] (Other ingredients) The buffer layer may contain other components, which are not particularly limited and may be appropriately selected depending on the purpose.

[0107] (Creating a buffer layer) As the composition for forming the buffer layer, for example, a buffer layer forming composition containing the above-mentioned components or a composition obtained by diluting the buffer layer forming composition with a solvent or the like is prepared. Examples of the solvent include organic solvents such as methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. The buffer layer-forming composition or the like is then applied to a release film or a substrate by a known method such as spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating to form a coating film, and the coating film is cured to form an intermediate layer on the substrate. In this embodiment, the coating film is preferably cured by irradiation with energy rays. Examples of energy rays include ultraviolet rays and electron beams, with ultraviolet rays being preferred. Furthermore, in this embodiment, it is preferable to cure the coating film by irradiating it with energy rays multiple times, which allows the degree of cure of the buffer layer to be controlled, and makes it easier to adjust the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer to fall within the above ranges. When the energy rays are ultraviolet rays, the ultraviolet irradiation conditions are preferably such that the illuminance of the ultraviolet rays is 30 to 500 mW / cm 2 , more preferably 50 to 340 mW / cm 2 and the irradiation amount (integrated light amount) of ultraviolet light is preferably 100 to 2500 mJ / cm 2 , more preferably 150 to 2000 mJ / cm 2 is. When ultraviolet irradiation is performed multiple times, the irradiation conditions are preferably such that the illuminance and dose are greater than those of the previous irradiation. Furthermore, after the coating film is exposed to oxygen and irradiated with energy rays, the coating film may be further irradiated with energy rays while being shielded from oxygen.

[0108] <Intermediate release layer> As described above, the composite sheet for forming a protective film of this embodiment may have an intermediate release layer between the buffer layer and the film for forming a protective film. The intermediate release layer is a layer provided to easily peel the buffer layer from the film for forming a protective film after the composite sheet for forming a protective film is attached to the projecting electrode-forming surface of the member with projecting electrodes and the film for forming a protective film is attached to the projecting electrode-forming surface.

[0109] The intermediate release layer is in the form of a sheet or film, and the material constituting the layer is not particularly limited. The intermediate release layer preferably comprises ethylene-vinyl acetate copolymer (EVA). The intermediate release layer may contain other components in addition to those described above. The other components are not particularly limited and are appropriately selected depending on the purpose.

[0110] The intermediate release layer may be a single layer or a plurality of layers, such as two or more layers. When the intermediate release layer is a plurality of layers, these layers may be the same or different from each other, and the combination of these layers is not particularly limited.

[0111] The thickness of the intermediate release layer is not particularly limited, but is preferably 5 to 30 μm, more preferably 6 to 25 μm, and even more preferably 7 to 20 μm.

[0112] <Base material> The substrate is in the form of a sheet or film, and examples of the constituent materials thereof include the following various resins. Examples of resins constituting the substrate include polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); polyolefins other than polyethylene such as polypropylene, polybutene, polybutadiene, polymethylpentene, and norbornene resin; ethylene-based copolymers (copolymers obtained using ethylene as a monomer) such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, and ethylene-norbornene copolymer; and vinyl chloride-based resins (copolymers obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymer. resins obtained by the above method); polystyrene; polycycloolefin; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalenedicarboxylate, and wholly aromatic polyesters in which all structural units have aromatic cyclic groups; copolymers of two or more of the above polyesters; poly(meth)acrylic acid esters; polyurethanes; polyurethane acrylates; polyimides; polyamides; polycarbonates; fluororesins; polyacetals; modified polyphenylene oxides; polyphenylene sulfides; polysulfones; polyether ketones; and the like. Further, examples of the resin constituting the substrate include polymer alloys such as mixtures of the above polyesters with other resins. The polymer alloys of the above polyesters with other resins preferably contain a relatively small amount of resin other than polyester. Further, examples of the resin constituting the substrate include crosslinked resins in which one or more of the resins exemplified above are crosslinked; and modified resins such as ionomers using one or more of the resins exemplified above. The resin constituting the substrate may be used alone or in combination of two or more.

[0113] The substrate may be a single layer or a multi-layer substrate of two or more layers. When the substrate is a multi-layer substrate, the multi-layer substrate may be the same or different from one another, and the combination of the multi-layer substrate is not particularly limited.

[0114] The thickness of the substrate is not particularly limited, but is preferably 5 to 1,000 μm, more preferably 10 to 500 μm, even more preferably 15 to 300 μm, and even more preferably 20 to 150 μm.

[0115] The substrate preferably has a high thickness precision, i.e., a thickness variation that is suppressed regardless of location. Among the above-mentioned constituent materials, examples of materials with a high thickness precision that can be used to constitute the substrate include polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyesters other than polyethylene terephthalate and polybutylene terephthalate, ethylene-vinyl acetate copolymer, etc.

[0116] In addition to the main constituent materials such as the resin, the substrate may contain various known additives such as fillers, colorants, antioxidants, organic lubricants, catalysts, and softeners (plasticizers).

[0117] The substrate may be transparent or opaque, may be colored as desired, or may have other layers vapor-deposited thereon.

[0118] The substrate can be produced by a known method. For example, a substrate containing a resin can be produced by molding a resin composition containing the resin.

[0119] <Method of manufacturing the composite sheet for forming a protective film> The composite sheet for forming a protective film of this embodiment can be produced by laminating the above-mentioned layers in order so that they are in a corresponding positional relationship. For example, a composite sheet for forming a protective film having a laminated structure of a buffer layer and a film for forming a protective film can be produced by the method shown below. The buffer layer-forming composition of this embodiment is applied to the release-treated surface of the release film and cured to form a buffer layer on the release film. Separately, the resin composition for a film for forming a protective film of this embodiment is applied to the release-treated surface of a release film, and dried as necessary, to form a film for forming a protective film on the release film. Next, the exposed surface of the buffer layer opposite the release film is bonded to the exposed surface of the protective film-forming film opposite the release film, thereby obtaining a composite sheet for protective film-forming having a laminated structure of the buffer layer and the film for protective film-forming. The release films provided on the film for forming a protective film and on the buffer layer in the composite sheet for forming a protective film may be removed at any stage from the production of the composite sheet for forming a protective film to the end of use.

[0120] Furthermore, for example, a composite sheet for forming a protective film having a substrate, a buffer layer, and a film for forming a protective film in this order can be produced by the method shown below. A buffer layer is formed on a release film by applying a buffer layer-forming composition to one side of a substrate and curing it. A first laminate sheet is obtained in which the substrate and the buffer layer are laminated. If necessary, a release film may be provided on the side of the buffer layer in the first laminate sheet opposite the substrate. Separately, the resin composition for a film for forming a protective film of this embodiment is applied to the release-treated surface of a release film, and dried as necessary, to form a film for forming a protective film on the release film. Next, the exposed surface of the buffer layer in the first laminate sheet opposite the substrate is bonded to the exposed surface of the protective film-forming film opposite the release film, thereby obtaining a composite sheet for protective film-forming having a configuration in which the substrate, buffer layer, protective film-forming film, and release film are laminated in this order. The release film provided on the film for forming a protective film in the composite sheet for forming a protective film may be removed at any stage from after the production of the composite sheet for forming a protective film to after use.

[0121] A composite sheet for forming a protective film having layers other than the above-mentioned layers can be produced by adding or omitting appropriate steps in the above-mentioned production method so that the stacking positions of each layer are in the desired positions.

[0122] [Method of manufacturing semiconductor device] The method for manufacturing a semiconductor device according to this embodiment will be described below with reference to the drawings.

[0123] The method for manufacturing a semiconductor device according to the present embodiment includes a step of attaching a protective film-forming film surface of a protective film-forming film or a protective film-forming composite sheet to a wafer (a wafer with protruding electrodes), and a step of singulating a laminate of the protective film-forming film and the wafer or a laminate of a protective film obtained by thermally curing the protective film-forming film and the wafer. In detail, the method for manufacturing a semiconductor device according to this embodiment is preferably a manufacturing method including the following steps 1 to 5. Step 1: A step of laminating the protective film-forming composite sheet on the semiconductor wafer by attaching the protective film-forming film of the composite sheet for forming a protective film of this embodiment to the surface of the semiconductor wafer on which the protruding electrodes are formed, and causing the tops of the protruding electrodes to protrude from the protective film-forming film (hereinafter also referred to as the "attaching step"). Step 2: A step of removing layers other than the protective film-forming film from the composite sheet for forming a protective film laminated in Step 1 (hereinafter also referred to as the "removing step"). Step 3: A step of forming a protective film by curing the protective film-forming film on the semiconductor wafer (hereinafter also referred to as the "curing step"). Step 4: A step of singulating the laminate (a laminate of a semiconductor wafer and a protective film) obtained in Step 3 to produce semiconductor chips (hereinafter also referred to as the "singulation step"). Step 5: A step of flip-chip bonding and mounting the semiconductor chip with the protective film on the substrate (hereinafter also referred to as the "mounting step"). Each step will be described below with reference to the drawings. In the following description, the case where the composite sheet for forming a protective film 1c is used will be described as an example, but it goes without saying that the composite sheet for forming a protective film 1a, 1b, 1d, or 1e may also be used. In the following description, bumps are used as examples of protruding electrodes, but in the present invention, protruding electrodes other than bumps may of course be used.

[0124] <Process 1: Pasting process> FIG. 6 is a schematic cross-sectional view for explaining the bonding step. 6(a) and (b) show a process of attaching a composite sheet 1c for forming a protective film to a bump formation surface 20a of a semiconductor wafer 20. In the bonding step, for example, first, the composite sheet 1c for forming a protective film is placed so that the film 12 for forming a protective film faces the bump formation surface 20a of the semiconductor wafer 20 as shown in FIG. 6(a). Next, the protective film forming film 12 is brought into contact with the bumps 21 on the semiconductor wafer 20, and the composite sheet 1c for forming a protective film is pressed against the semiconductor wafer 20. By pressing, the protective film forming film 12 is pressure-bonded to the surfaces of the bumps 21 and the bump formation surface 20a of the semiconductor wafer 20, in that order. When the composite sheet 1 for forming a protective film is pressure-bonded to the semiconductor wafer 20, the film 12 for forming a protective film is pressed through the buffer layer 11 and pressure is applied from the bumps 21, causing tears in the film 12 for forming a protective film. Finally, as shown in Fig. 6(b), the tops of the bumps 21 penetrate the film 12 for forming a protective film and protrude. In order to make the tops of the bumps 21 protrude through the protective film-forming film 12, the storage modulus (G') of the buffer layer at 80°C is preferably 0.10 MPa or more, as described above. In order to improve the bump embeddability, the loss tangent (tanδ) of the buffer layer at 80°C is preferably 1.05 or more, as described above.

[0125] The height of the bumps 21 is not particularly limited, but is preferably 120 to 300 μm, more preferably 150 to 270 μm, and even more preferably 180 to 240 μm. In this specification, the "height of a bump" means the height of the bump at the highest point from the bump formation surface.

[0126] The width of the bump 21 is not particularly limited, but is preferably 170 to 350 μm, more preferably 200 to 320 μm, and even more preferably 230 to 290 μm. In this specification, the "bump width" means the maximum length of a line segment obtained by connecting two different points on the bump surface when the bump is viewed in a plan view looking down on the bump from a direction perpendicular to the bump formation surface.

[0127] The distance between adjacent bumps 21 is not particularly limited, but is preferably 250 to 800 μm, more preferably 300 to 600 μm, and even more preferably 350 to 500 μm. In this specification, the "distance between adjacent bumps" means the minimum distance between the surfaces of adjacent bumps.

[0128] The composite sheet 1 for forming a protective film can be pressure-bonded to the semiconductor wafer 20 by any known method for pressing and attaching various sheets to an object, such as a method using a roller laminator. The heating temperature when the composite sheet 1 for forming a protective film is pressure-bonded to the semiconductor wafer 20 is not particularly limited, and may be, for example, 80 to 100°C, and preferably 85 to 95°C. The pressure when the composite sheet for forming a protective film 1 is pressure-bonded to the semiconductor wafer 20 is not particularly limited, and may be, for example, 0.1 to 1.5 MPa, and preferably 0.3 to 1 MPa. The speed at which the composite sheet 1 for forming a protective film is attached to the semiconductor wafer 20 is not particularly limited, and is usually about 2 to 3 mm / s.

[0129] After the bonding step, if necessary, the surface (back surface) of the semiconductor wafer 20 opposite the bump formation surface 20a may be ground, and further, another composite sheet for forming a protective film (not shown) may be bonded to the back surface after grinding.

[0130] <Step 2: Removal step> FIG. 7 is a schematic cross-sectional view for explaining the removal step. After the bonding process, as shown in Figure 7, layers other than the protective film formation film 12 are removed from the protective film formation composite sheet 1c, thereby obtaining a semiconductor wafer 30 with a protective film formation film, which comprises a semiconductor wafer 20 and the protective film formation film 12 provided on the bump formation surface 20a of the semiconductor wafer 20. The layers other than the protective film-forming film 12 can be removed by a known method.

[0131] <Process 3: Curing process> FIG. 8 is a schematic cross-sectional view for explaining the curing step. 8, the protective film-forming film 12 is thermally cured to form a protective film 12' on the bump-forming surface 20a of the semiconductor wafer 20. This results in a protective film-coated semiconductor wafer 40 having the protective film 12' on the bump-forming surface 20a of the semiconductor wafer 20. The conditions for thermally curing the protective film-forming film are not particularly limited and may be adjusted and determined as appropriate depending on the type of material constituting the protective film-forming film, etc. However, from the viewpoint of improving chipping suppression, it is preferable to perform thermal curing without pressure (atmospheric pressure). The thermal curing conditions are typically a temperature of 90° C. to 200° C. for 1 to 5 hours. When pressure is applied, the pressure is typically 0.2 to 1.0 MPa. In the case of pressureless heat curing, the temperature is preferably 130° C. for 4 hours. In the case of pressure heat curing, the conditions are preferably 130°C, 4 hours, and 0.5 MPa.

[0132] <Process 4: Singulation process> FIG. 9 is a schematic cross-sectional view for explaining the singulation step. 9, in the singulation step, cutting is performed from the protective film 12' side with a dicing blade to collectively cut the protective film 12' and the semiconductor wafer 20. This results in a semiconductor chip 60 with a protective film, which has the protective film 120' after cutting on the bump-forming surface of the semiconductor chip 50. In this embodiment, since the protective film-forming film that satisfies the above parameters is used, chipping is suppressed during cutting with a dicing blade. Therefore, a decrease in yield due to chipping in the singulation process can be suppressed, and the manufacturing yield of semiconductor devices (semiconductor chips) can be improved.

[0133] The dividing step and cutting step can be carried out by known methods. The order in which the dividing step and the cutting step are performed is not particularly limited, but it is preferable to perform the dividing step and the cutting step simultaneously, or to perform the dividing step and the cutting step in that order. When the dividing step and the cutting step are performed in this order, for example, the dividing step may be performed by a known dicing method, and then the cutting step may be performed immediately thereafter. Dicing can be performed by providing a dicing sheet (not shown) on the back surface of the semiconductor wafer 20 (which may be the back surface after grinding). In the cutting step, the protective film 12' is cut along the planned or completed dividing points of the semiconductor wafer 20 (in other words, along the outer periphery of the semiconductor chip 40).

[0134] <Process 5: Mounting process> In the mounting process, the semiconductor chip with the protective film obtained in the curing process is flip-chip connected to the electrodes (wiring) of the substrate at the tops of the bumps (not shown). At this time, the semiconductor chip with the protective film is connected to the circuit formation surface of the substrate.

[0135] Thereafter, a semiconductor package is produced according to a known method using the circuit board thus obtained on which the semiconductor chip is already mounted, and the desired semiconductor device can be manufactured using this semiconductor package.

[0136] <Modification of the semiconductor device manufacturing method> The protective film-forming film of this embodiment exhibits excellent chipping suppression even when uncured. Therefore, the singulation step of step 4 may be performed before the curing step of step 3, and the protective film-forming film may be thermally cured after the singulation step 4.

[0137] [Semiconductor Devices] According to one aspect of the present invention, there is provided the following semiconductor device. That is, a semiconductor device is provided in which a protective film or a protective film formed by heat-curing the protective film is laminated on the circuit surface of a wafer or a chip on the wafer, and in an electron microscope image obtained by observing a cross section of the protective film or the protective film in the observation area described below, the maximum diameter of the perfect circle when placed between fillers is less than 3.0 μm. <Observation area> When the thickness direction of the protective film or protective film is defined as the vertical direction and the direction perpendicular to the thickness direction of the protective film or protective film is defined as the horizontal direction, a vertical area of ​​10% of the thickness is excluded from the side opposite the side that is attached to the substrate, and the observation area is the surface formed by a 15 μm side A and a 33 μm horizontal side B from the end of the excluded area toward the side that is attached to the substrate. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area.

[0138] [Wafer protection method] In one aspect of the present invention, there is provided a method for protecting a wafer, the method comprising: (1) A wafer protection method, which suppresses chipping of the wafer by attaching a protective film-forming film to a wafer and then singulating a laminate of the protective film-forming film and the wafer or a laminate of a protective film formed by heat-curing the protective film-forming film and the wafer. (2) A wafer protection method, which comprises attaching the protective film forming film surface of a composite sheet for forming a protective film to a wafer, and then singulating a laminate of the protective film forming film and the wafer, or a laminate of a protective film formed by heat-curing the protective film forming film and the wafer, thereby suppressing chipping of the wafer. [Example]

[0139] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0140] [Preparation of substrate with buffer layer] (1) Evaluation of the physical properties of the buffer layer A buffer layer-forming composition A was obtained by blending 40 parts by mass of aliphatic urethane acrylate (CN966J75 NS, manufactured by Arkema Inc.), 40 parts by mass of isobornyl acrylate (IBXA), and 20 parts by mass of dodecyl acrylate, for a total of 100 parts by mass, with 3.0 parts by mass of a photopolymerization initiator (Irgacure 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), manufactured by BASF) and 1.5 parts by mass of a chain transfer agent (Karenz MT PE1 (pentaerythritol tetrakis(3-mercaptobutyrate)), manufactured by Showa Denko K.K.). The obtained buffer layer-forming composition A was applied to a PET-based release film (manufactured by Lintec Corporation, SP-PET382150, thickness 38 μm) using a knife method to a thickness of 200 μm to form a buffer layer-forming composition layer. Next, the formed buffer layer-forming composition layer was laminated with a PET-based release film (manufactured by Lintec Corporation, SP-PET381130, thickness 38 μm) to insulate the buffer layer-forming composition layer from oxygen. Subsequently, a high-pressure mercury lamp was used to apply the composition at an illuminance of 80 mW / cm. 2 , cumulative light intensity 200mJ / cm 2 After ultraviolet irradiation under the conditions of 330 mW / cm using a metal halide lamp, 2 , irradiation amount 1260mJ / cm 2 The buffer layer-forming composition layer was cured by irradiating it with ultraviolet light under the conditions of (a) to (b), thereby obtaining a buffer layer having a thickness of 200 μm.

[0141] Next, a sample was prepared for measuring the shear storage modulus and loss tangent of the buffer layer. The sample had a diameter of 8 mm and a thickness of 1 mm (five 200 μm buffer layers stacked together). The shear storage modulus G' and loss tangent tanδ were measured using an Anton Paar MCR302 rheometer. The measurement conditions were as follows: The sample, from which the release films had been removed from the top and bottom, was sandwiched between parallel plates, and shear stress was applied to the sample at a measurement temperature of 0 to 100°C, a gap of 1 mm, a strain of 0.05 to 0.5%, and an angular frequency of 1 Hz. The shear storage modulus G' and loss tangent tanδ at 80°C were calculated. The shear storage modulus G' and loss tangent tan δ of the buffer layer at 80° C. were as follows. Shear storage modulus G' at 80°C: 0.16 MPa Loss tangent tanδ at 80℃: 1.17

[0142] (2) Preparation of substrate with buffer layer The buffer layer-forming composition A was applied to one side of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., "Polyester Film "Lumilar" U34", thickness 75 μm) as a substrate using a knife method to form a buffer layer composition layer with a thickness of 400 μm. Next, the formed buffer layer composition layer was laminated with a PET-based release film (manufactured by Lintec Corporation, SP-PET381130, thickness 38 μm) to insulate the buffer layer composition layer from oxygen. Subsequently, a high-pressure mercury lamp was used to apply the coating at an illuminance of 80 mW / cm. 2 , cumulative light intensity 200mJ / cm 2 After ultraviolet irradiation under the conditions of 330 mW / cm using a metal halide lamp, 2 , irradiation amount 1260mJ / cm 2 The buffer layer composition layer was cured by irradiating it with ultraviolet light under the conditions of (a) to (b), thereby forming a buffer layer having a thickness of 400 μm. As a result, a substrate with a buffer layer was obtained, which was configured by laminating the substrate, buffer layer, and release film in this order in the thickness direction.

[0143] [Raw materials for protective film-forming composition] The raw materials used in the production of the protective film-forming composition are shown below. Polymer component (A) (A)-1: Polyvinyl butyral having structural units represented by the following formulas (i)-1, (i)-2, and (i)-3 ("S-LEC BL-10" manufactured by Sekisui Chemical Co., Ltd., weight average molecular weight 25,000, glass transition temperature 59°C). [ka] (In the formula, l is about 28, m is 1 to 3, and n is an integer of 68 to 74.) (A)-2: Polyimide ("Semicofine" manufactured by Toray Industries, Inc.) (A)-3: Polyarylate resin ("Unifiner M-2040H" manufactured by Unitika Ltd.) Epoxy resin (B1) (B1)-1: Liquid modified bisphenol A epoxy resin (DIC Corporation, "Epiclon HP-A-4860," molecular weight 900, epoxy equivalent 410 g / eq) (B1)-2: Dicyclopentadiene-type epoxy resin (DIC Corporation "Epicron HP-7200HH" epoxy equivalent: 254-264g / eq) Heat hardener (B2) (B2)-1: O-cresol novolac resin (DIC Corporation "Phenolite KA-1160") Curing accelerator (C) (C)-1:2-Phenyl-4,5-dihydroxymethylimidazole ("Curezol 2PHZ-PW" manufactured by Shikoku Chemicals Corporation) ·Filling material (D) (D)-1: Spherical silica modified with epoxy groups ("Admanano YA050C-MKK" manufactured by Admatechs Co., Ltd., average particle size 50 nm) Additives (I) (G)-1: Surfactant (acrylic polymer, BYK "BYK-361N") (G)-2: Silicone oil (aralkyl-modified silicone oil, "XF42-334" manufactured by Momentive Performance Materials Japan) (G)-3: Silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-1403")

[0144] [Production Example 1: Preparation of Composite Sheet A1 for Forming Protective Film] (1) Preparation of protective film Polymer component (A)-1 (50 parts by weight), epoxy resin (B1)-1 (290 parts by weight), epoxy resin (B1)-2 (240 parts by weight), heat curing agent (B2)-1 (170 parts by weight), curing accelerator (C)-1 (1 part by weight), filler (D)-1 (220 parts by weight), additive (G)-1 (25 parts by weight), and additive (G)-2 (4 parts by weight) were dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to obtain a composition for forming a protective film with a total concentration of all components other than the solvent of 45% by weight. Note that the amounts of all components other than the solvent shown here are the amounts of the target product excluding the solvent.

[0145] (2) Preparation of protective film A PET-based release film (SP-PET381031, manufactured by Lintec Corporation, thickness 38 μm) was used as the release film, and the protective film-forming composition obtained above was applied to the release-treated surface using a die coater, and dried at 100°C for 2 minutes to produce a 30 μm-thick thermosetting protective film-forming film.

[0146] (3) Preparation of intermediate release layer-forming composition At room temperature, ethylene-vinyl acetate copolymer (weight average molecular weight (Mw) 55,000, VA content 20% by mass) was dissolved in toluene to prepare a toluene solution with a solids concentration of 12% by mass, which was used as a composition for forming an intermediate release layer.

[0147] (4) Formation of intermediate peeling layer The composition for forming an intermediate release layer obtained above was applied to the release-treated surface of a newly prepared release film (manufactured by Lintec Corporation, product name "SP-PET381031", thickness 38 μm), and the composition was heated and dried at 100°C for 2 minutes to form an intermediate release layer 10 μm thick.

[0148] (5) Formation of composite sheet for forming protective film From the substrate with the buffer layer obtained above, the release film was removed, and the exposed surface of the buffer layer thus obtained was bonded to the exposed surface of the intermediate release layer obtained above, thereby obtaining a laminated sheet further laminated with an intermediate release layer. Next, the release film was removed from the intermediate release layer after bonding, and the exposed surface of the single-sided release film-attached protective film-forming film obtained above was bonded to the exposed surface of the intermediate release layer. As a result, a composite sheet A1 for forming a protective film was obtained, which was composed of a substrate (75 μm thick), a buffer layer (400 μm thick), an intermediate release layer (10 μm thick), and a protective film-forming film (30 μm thick) laminated in this order in the thickness direction.

[0149] [Production Example 2: Preparation of Composite Sheet A2 for Forming Protective Film] A composite sheet A2 for forming a protective film was obtained in the same manner as in Production Example 1, except that the composition for forming a protective film was changed to the following formulation. <Solid content of the protective film-forming composition of Production Example 2> Polymer component (A)-3 (250 parts by mass), epoxy resin (B1)-1 (290 parts by mass), heat curing agent (B2)-1 (170 parts by mass), curing accelerator (C)-1 (1 part by mass), filler (D)-1 (220 parts by mass), additive (G)-1 (25 parts by mass), and additive (G)-3 (10 parts by mass)

[0150] Comparative Production Example 1: Preparation of Composite Sheet B1 for Forming Protective Film A composite sheet for forming a protective film B2 was obtained in the same manner as in Production Example 1, except that the solid content of the composition for forming a protective film was changed as follows. <Solid content of the protective film-forming composition of Comparative Production Example 1> Polymer component (A)-1 (100 parts by mass), epoxy resin (B1)-1 (290 parts by mass), epoxy resin (B1)-2 (220 parts by mass), heat curing agent (B2)-1 (170 parts by mass), curing accelerator (C)-1 (2 parts by mass), filler (D)-1 (200 parts by mass), additive (G)-1 (25 parts by mass), and additive (G)-2 (3 parts by mass).

[0151] [Example 1: Preparation of evaluation sample 1] The surface of the composite sheet A1 for forming a protective film was used as the bonding surface and the sheet was bonded to an 8-inch diameter mirror wafer (750 μm thick) by thermocompression bonding. The bonding was performed using a bonding device (a roller laminator, RAD-3520 F / 12 manufactured by Lintec Corporation) under conditions of a table temperature of 90°C, a bonding speed of 5 mm / sec, a bonding pressure of 0.5 MPa, and a roller bonding height of -0 μmt while heating the wafer. Next, using a multi-wafer mounter ("RAD-2700 F / 12" manufactured by Lintec Corporation), the substrate, buffer layer, and intermediate release layer were removed from the composite sheet for forming a protective film A1 to expose the film for forming a protective film. Thereafter, the protective film-forming film was cured under heat and no pressure to prepare Evaluation Sample 1. The heat and no pressure curing was carried out using Lintec Corporation's RAD-9100 at 130°C for 4 hours under no pressure (atmospheric pressure).

[0152] [Example 2: Preparation of evaluation sample 2] Evaluation sample 2 was produced in the same manner as in Example 1, except that the protective film-forming film was cured under pressure (0.5 MPa) (curing conditions: 130° C., 4 hours).

[0153] [Example 3: Preparation of evaluation sample 3] Evaluation sample 3 was produced using composite sheet A2 for forming a protective film instead of composite sheet A1 in the same manner as in Example 1. However, in Example 3, the film for forming a protective film was left uncured without being thermally cured.

[0154] Comparative Example 1: Preparation of Evaluation Sample 1' An 8-inch diameter mirror wafer (750 μm thick) was used as it was as an evaluation sample 1′.

[0155] Comparative Example 2: Preparation of Evaluation Sample 2′ A polyimide solution was dropped onto the mirror surface of an 8-inch diameter mirror wafer (750 μm thick) and a 10 μm thick film was formed by spin coating to prepare an evaluation sample 2′.

[0156] Comparative Example 3: Preparation of Evaluation Sample 3′ Using the composite sheet B1 for forming a protective film instead of the composite sheet A1 for forming a protective film, an evaluation sample 3' was produced in the same manner as in Example 1. However, in Comparative Example 3, the film for forming a protective film was left uncured without being thermally cured.

[0157] Comparative Example 4: Preparation of Evaluation Sample 4′ An evaluation sample 4' was prepared in the same manner as in Example 2, except that the composite sheet for forming a protective film B1 was used instead of the composite sheet for forming a protective film A1.

[0158] <Chipping evaluation> The evaluation samples were subjected to dicing (DC) using a dicing machine (DFD-6363) under the following conditions. Blade: ZH05-SD2000-N1-70 DD Rotational speed: 45,000 rpm ·DC speed: 10mm / s Blade cutting depth: 250μm XY index: 6mm

[0159] Thereafter, the DC portion of the evaluation sample 1' of Comparative Example 1 was observed with a digital microscope (Keyence, VHX-7000), and the kerf width and chipping width of the blade were measured. For the evaluation sample 2' of Comparative Example 2, the kerf width and chipping width of the blade were measured through the polyimide film in the same manner as in Comparative Example 1. For evaluation sample 3' and evaluation sample 3 of Comparative Example 3 and Example 3, after DC, the surface film was washed away using a solvent (MEK) to expose the wafer, and then the kerf width and chipping width were measured. For evaluation sample 4', evaluation sample 1, and evaluation sample 2 of Comparative Example 4, Example 1, and Example 2, the protective film was removed by plasma treatment (gas used: O2, gas flow rate: 90 sccm, output: 250 W, treatment time: 90 minutes) using a plasma device (manufactured by Samco, RIE-10NR) to expose the wafer, and then the kerf width and chipping width were measured. The evaluation was carried out using the width (total width) of "kerf + chipping", and the evaluation criteria were as follows, with ratings of 1 and 2 being considered acceptable. Rating 1: The average width is less than 40 μm, and the width when Cpk=1.67 is less than 45 μm. Evaluation 2: The average width is less than 40 μm, and the width when Cpk=1.67 is 45 μm or more and less than 48 μm. Evaluation 3: The average width is 40 μm or more and less than 44 μm, and the width when Cpk=1.67 is 48 μm or more and less than 52 μm. Rating 4: The average width is 44 μm or more, and the width when Cpk=1.67 is 52 μm or more and less than 60 μm. Rating 5: The average width is 44 μm or more, and the width when Cpk=1.67 is 60 μm or more.

[0160] <Circularity Diameter Evaluation> An observation surface of 30 μm in width and 30 μm in depth was prepared using a FIB-SEM (Zeiss Gemini SEM 560 manufactured by Zeiss), and then the observation surface was observed by SEM under conditions of an acceleration voltage of 5 kV and WD=5 mm. Then, a perfect circle that satisfies the following conditions was drawn in the shape of the white dots formed by inorganic substances such as Si in the observed image. 1. Touch at least two white dots. 2. Do not include white dots inside the circle Then, the maximum diameter of the drawn perfect circles was calculated. Whether or not the above conditions were met was determined by excluding a vertical area of ​​10% of the thickness from the surface opposite to the surface to be attached to the substrate, with the thickness direction of the sample being the vertical direction and the direction perpendicular to the thickness direction of the sample being the horizontal direction, and determining the observation area as the surface formed by a 15 μm side A and a 33 μm horizontal side B from the end of the excluded area toward the surface to be attached to the substrate.

[0161] <Evaluation of glass transition temperature (Tg) and storage modulus of protective film> Using each of the protective film-forming compositions used in Production Examples 1 and 2 and Comparative Production Example 1, test pieces of protective film-forming films measuring 5 mm x 20 mm (0.2 mm thick) were prepared. Similar test pieces were also prepared for the polyimide film used in Comparative Example 2. These test pieces were attached to a thermomechanical analyzer (manufactured by NETZSCH, product name "DMA242E") with a chuck distance of 15 mm, and the temperature was raised from -100°C to 200°C at a heating rate of 10°C / min while applying a strain at a frequency of 11 Hz, to measure the storage modulus and tan δ. The temperature at which tan δ peaked within the above measurement range was defined as the glass transition temperature (Tg), and the storage modulus at 23°C was determined.

[0162] The evaluation results are shown in Table 1. Electron microscope images of Example 1 and Comparative Example 4 are shown in FIG.

[0163] [Table 1]

[0164] From Table 1, we can see the following: As in Examples 1 to 3, when the diameter of the drawn circle is less than 3.0 μm, it is clear that chipping suppression is excellent. In contrast, when the diameter of the drawn circle is 3.0 μm or more, as in Comparative Examples 2 to 4, it is clear that chipping suppression is poor. [Explanation of symbols]

[0165] 1a, 1b, 1c, 1d Composite sheet for forming protective film 10 Base material 10a One side of the substrate 11 Buffer layer 12 Protective film forming film 13 Intermediate peeling layer 20 Semiconductor wafers 20a: Projection electrode (bump) forming surface of semiconductor wafer 21 Projecting electrode (bump) 30 Semiconductor wafer with protective film 40 Semiconductor wafer with protective film 50 semiconductor chips 60 Semiconductor chip with protective film

Claims

1. A thermosetting protective film to be attached to the circuit surface of a wafer, Contains a filler, In an electron microscope image obtained by observing a cross section of at least one of the following samples (1) to (3) in the following observation area, when a perfect circle is placed between the fillers, the maximum diameter of the perfect circle is less than 3.0 μm. A film for forming a protective film. Sample (1): Uncured protective film-forming film Sample (2): A protective film obtained by thermally curing the protective film-forming film at 130°C for 4 hours without pressure. Sample (3): A protective film obtained by thermally curing the protective film-forming film at 130°C under pressure for 4 hours. <Observation area> When the thickness direction of the samples (1) to (3) is defined as the vertical direction and the direction perpendicular to the thickness direction of the samples (1) to (3) is defined as the horizontal direction, a vertical area having a length of 10% of the thickness is excluded from the surface opposite to the surface to be attached to the adherend, and the observation area is the surface formed by a side A of 15 μm from the end of the excluded area toward the surface to be attached to the adherend and a horizontal side B of 33 μm. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area.

2. The film for forming a protective film according to claim 1 , wherein the wafer is a wafer with protruding electrodes.

3. The film for forming a protective film according to claim 1 or 2, which contains an acetal resin.

4. The film for forming a protective film according to claim 1 or 2, wherein the filler contains silica.

5. The film for forming a protective film according to claim 1 or 2, wherein the filler has an average particle size of 500 nm or less.

6. The film for forming a protective film according to claim 1 or 2, which has a glass transition temperature of 60°C or higher.

7. A composite sheet for forming a protective film, having a laminated structure of a substrate and the film for forming a protective film according to claim 1 or 2.

8. The composite sheet for forming a protective film according to claim 7 , further comprising a buffer layer between the substrate and the film for forming a protective film.

9. The composite sheet for forming a protective film according to claim 8 , further comprising an intermediate release layer between the buffer layer and the film for forming a protective film.

10. A step of attaching the film for forming a protective film according to claim 1 or 2 to a wafer; A method for manufacturing a semiconductor device, comprising a step of dividing a laminate of the film for forming a protective film and the wafer, or a laminate of the film for forming a protective film, which is thermally cured, and the wafer, by blade dicing.

11. A step of attaching the film surface for forming a protective film of the composite sheet for forming a protective film according to claim 7 or 8 to a wafer; A method for manufacturing a semiconductor device, comprising a step of dividing a laminate of the film for forming a protective film and the wafer, or a laminate of the film for forming a protective film, which is thermally cured, and the wafer, by blade dicing.

12. The method for manufacturing a semiconductor device according to claim 10 or 11, wherein the thermal curing is carried out without applying pressure.

13. A wafer protection method comprising: applying a protective film-forming film according to claim 1 or 2 to a wafer; and then dicing a laminate of the protective film-forming film and the wafer, or a laminate of a protective film formed by thermally curing the protective film-forming film and the wafer, by blade dicing, thereby suppressing chipping of the wafer.

14. A wafer protection method comprising: attaching the protective film forming film surface of the composite sheet for forming a protective film described in claim 7 or 8 to a wafer; and then dicing a laminate of the protective film forming film and the wafer, or a laminate of a protective film formed by heat-curing the protective film forming film and the wafer, by blade dicing, thereby suppressing chipping of the wafer.

15. A semiconductor device in which a protective film or a protective film obtained by thermally curing the protective film is laminated on a wafer or a circuit surface of a chip on the wafer, A semiconductor device in which, in an electron microscope image obtained by observing a cross section of the protective film or protective film in the observation area described below, the maximum diameter of a perfect circle placed between fillers is less than 3.0 μm. <Observation area> When the thickness direction of the protective film or protective film is defined as the vertical direction and the direction perpendicular to the thickness direction of the protective film or protective film is defined as the horizontal direction, a vertical area of ​​10% of the thickness is excluded from the surface opposite to the surface to be attached to the substrate, and the observation area is the surface formed by a 15 μm side A and a 33 μm horizontal side B from the end of the excluded area toward the surface to be attached to the substrate. However, if the length of side A is less than 15 μm, the entire length in the surface direction from the end of the exclusion range to the adherend is selected as side A', and the surface formed by side A' and side B is the observation area.

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