Composite sheet for forming protective film and method for manufacturing semiconductor device

Abstract

To provide a composite sheet for forming a protective film that achieves both bump penetration and bump embedding properties of a protective film forming layer, and a method for manufacturing a semiconductor device using the composite sheet for forming a protective film.SOLUTION: A composite sheet for forming a protective film used to form a protective film on a bump-forming surface of a bumped member, has a laminated structure of a buffer layer and a protective film-forming layer, in which the buffer layer has a storage modulus (G') of 0.08 MPa or more at 80°C and the buffer layer has a loss tangent (tanδ) of 1.02 or more at 80°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite sheet for forming a protective film and a method for manufacturing 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 called bumps are formed on the electrodes of a chip and the electrodes of the substrate are directly connected to the electrodes of the chip via the bumps, instead of the conventional wire bonding method, which uses metal wires to connect semiconductor elements. In such a flip-chip connection type mounting method, a resin layer is provided to cover the bumps of the bumped wafer, bumped chip, etc., depending on various purposes. Examples of such a resin layer include a protective layer for protecting bumped members such as the bumped wafer and bumped chip.

[0003] However, when a resin layer covers the bumps, the resin layer on the bumps must be mechanically pushed aside to ensure electrical connection between the bumps and the electrodes on the substrate. This poses a problem in terms of connection reliability between the bumped chip and the substrate. Furthermore, when connecting the bumped chip to the substrate by reflow processing, the molten solder from the bumps is covered by the resin layer, preventing the self-alignment effect (the phenomenon in which misalignment between the electrodes on the chip and the substrate is automatically corrected to the correct position during reflow).

[0004] In order to solve the above problems, for example, a method has been proposed that includes a step of forming a resin layer on the bump-forming surface of a bumped member on which bumps are formed, and a step of performing a plasma treatment on the resin layer to remove the resin layer covering the surface of the bumps (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 194431 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method described in Patent Document 1 requires a vacuum device and various gases for plasma treatment. Therefore, the inventors investigated how to ensure the connection reliability between a bumped chip and a substrate without performing special treatments such as plasma treatment by using a composite sheet for forming a protective film having a laminated structure of a buffer layer and a protective film forming layer, and by ensuring that the bumps penetrate the protective film forming layer well when this is attached to a wafer with bumps, thereby preventing resin residues and the like from the protective film forming layer from adhering to the tops of the bumps. However, when trying to ensure the bump penetration ability of the protective film forming layer, it was found to be difficult to ensure the penetration ability of the protective film forming layer into the periphery of the bump base (hereinafter also referred to as "bump embedding ability").

[0007] Therefore, an object of the present invention is to provide a composite sheet for forming a protective film that achieves both bump penetration and bump embedding properties of a protective film forming layer, and a method for manufacturing a semiconductor device using the composite sheet for forming a protective film. [Means for solving the problem]

[0008] According to the present invention, the following [1] to [4] are provided. [1] A composite sheet for forming a protective film for forming a protective film on a bump-formed surface of a bumped member, It has a laminated structure of a buffer layer and a protective film forming layer, The buffer layer has a storage modulus (G') of 0.08 MPa or more at 80°C, and The composite sheet for forming a protective film, wherein the loss tangent (tan δ) of the buffer layer at 80°C is 1.02 or more. [2] The laminate structure further comprises a substrate, The composite sheet for forming a protective film according to [1] above, wherein the substrate is laminated on the buffer layer side of the laminate structure. [3] The laminate structure further comprises an intermediate release layer; The composite sheet for forming a protective film according to the above [1] or [2], which has the intermediate release layer between the buffer layer and the protective film forming layer. [4] A method for manufacturing a semiconductor device, comprising the step of forming a protective film on a bump-formed surface of a bumped member using the composite sheet for forming a protective film according to any one of [1] to [3] above. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a composite sheet for forming a protective film that achieves both bump penetration and bump embedding properties of a protective film forming layer, and a method for manufacturing a semiconductor device using the composite sheet for forming a protective film. [Brief explanation of the drawings]

[0010] [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] 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 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. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] 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."

[0013] 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.

[0014] 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.

[0015] In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," and the same applies to other similar terms.

[0016] In this specification, the term "bumped member" refers to a "bumped semiconductor wafer" or a "bumped semiconductor chip." Furthermore, the "circuit side" of a semiconductor wafer or semiconductor chip refers to the side on which a circuit is formed, and the "back side" of a semiconductor wafer or semiconductor chip refers to the side opposite to the circuit side.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] [Embodiments of the composite sheet for forming a protective film according to the present embodiment] The composite sheet for forming a protective film of this embodiment is a composite sheet for forming a protective film on a bump-formed surface of a bumped member on which bumps are formed, It has a laminated structure of a buffer layer and a protective film forming layer, The buffer layer has a storage modulus (G') of 0.08 MPa or more at 80°C, and The loss tangent (tan δ) of the buffer layer at 80° C. is 1.02 or more.

[0022] The present inventors have conducted extensive research to solve the above problems, and as a result have found that both the bump penetration property and the bump embeddability of the protective film-forming layer can be achieved by appropriately adjusting the storage modulus (G') at 80°C and the loss tangent (tan δ) at 80°C of the buffer layer, thereby completing the present invention.

[0023] <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 must be 0.08 MPa or more. If the storage modulus (G') of the buffer layer at 80°C is less than 0.08 MPa, bump penetration cannot be ensured, and it becomes difficult to ensure connection reliability between the bumped chip and the substrate due to resin residue on the top of the bump, etc. Here, from the viewpoint of making it easier to improve bump penetration, the storage modulus (G') of the buffer layer at 80°C is preferably 0.10 MPa or more, 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 easily adjusting the loss tangent (tanδ) of the buffer layer at 80°C to 1.02 or more and making it easier to improve the bump embeddability. The storage modulus (G') of the buffer layer at 80°C is a value measured by the method described in the examples below.

[0024] <Buffer layer loss tangent (tanδ) 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. must be 1.02 or more. If the loss tangent (tan δ) of the buffer layer at 80° C. is less than 1.02, it becomes difficult to ensure the bump embedding properties. Here, from the viewpoint of improving the bump embeddability, the loss tangent (tan δ) of the buffer layer at 80°C is preferably 1.05 or more, 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 (tan δ) of the buffer layer at 80°C is preferably 2.00 or less, from the viewpoint of easily adjusting the storage modulus (G') of the buffer layer at 80°C to 0.08 or more and making it easier to achieve good bump penetration. The loss tangent (tan δ) of the buffer layer at 80° C. means a value measured by the method described in the examples below.

[0025] <Configuration of the composite sheet for forming a protective film> The composite sheet for forming a protective film of the present embodiment may be composed of only the buffer layer and the protective film-forming layer, but may also have layers other than these layers. Examples of such other layers include a substrate, an intermediate release layer, a release film, an adhesive layer, and an antistatic layer. Hereinafter, first to fourth embodiments will be described as examples of the configuration of the composite sheet for forming a protective film of this embodiment.

[0026] (First aspect) A first aspect of the composite sheet for forming a protective film of this embodiment is shown in FIG. 1 has a protective film-forming layer 12 and a buffer layer 11 formed on one surface of the protective film-forming layer 12. Although not shown, the other surface of the protective film-forming layer 12 may be provided with a release film, a tape having an adhesive, or the like.

[0027] (Second aspect) A second 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 second embodiment has a substrate laminated on the buffer layer side of the laminate structure of the first embodiment. That is, the composite sheet for forming a protective film 1b of the second embodiment has a substrate 10, a buffer layer 11 laminated on one surface 10a of the substrate 10, and a protective film forming layer 12 laminated on the surface of the buffer layer 11 opposite the substrate 10, as shown in Fig. 2. Although not shown, the surface of the protective film forming layer 12 opposite the buffer layer 11 may be provided with a release film or a tape having an adhesive.

[0028] (Third aspect) A third 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 third embodiment has an intermediate release layer between the buffer layer and the protective film-forming layer in the laminate structure of the first embodiment. That is, the composite sheet for forming a protective film 1c of the third embodiment has an intermediate release layer 13 between the buffer layer 11 and the protective film-forming layer 12, as shown in Fig. 3. Although not shown, a release film or a tape having an adhesive may be provided on the surface of the protective film-forming layer 12 opposite to the intermediate release layer 13.

[0029] (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 a substrate laminated on the buffer layer side of the laminate structure of the first embodiment, and has an intermediate release layer between the buffer layer and the protective film-forming layer. That is, as shown in Fig. 4, the composite sheet for forming a protective film 1d of the fourth embodiment has a substrate 10, a buffer layer 11 laminated on one side of the substrate 10, an intermediate release layer 13 laminated on the side of the buffer layer 11 opposite the substrate 10, and a protective film-forming layer 12 laminated on the side 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 side of the protective film-forming layer 12 opposite the intermediate release layer 13.

[0030] <Buffer layer> The buffer layer is a layer that has a buffering effect against forces applied to the buffer layer and to layers directly or indirectly adjacent thereto. Here, the "layer directly or indirectly adjacent to the buffer layer" mainly refers to the protective film-forming layer in this embodiment.

[0031] 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.

[0032] The thickness of the buffer layer can be adjusted appropriately depending on the height of the bump to be protected, but from the viewpoint of making it easier to achieve the effects of the present invention even for relatively tall bumps, it is preferably 150 to 1,000 μm, more preferably 180 to 800 μm, and even more preferably 200 to 600 μm.

[0033] In this embodiment, the buffer layer must have a storage modulus (G') of 0.08 MPa or more at 80°C and a loss tangent (tanδ) of 1.02 or more at 80°C. The storage modulus (G') and loss tangent (tanδ) at 80°C of the buffer layer can be adjusted appropriately by adjusting the composition, degree of curing, etc. of the buffer layer. 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.

[0034] (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. From the viewpoint of easily adjusting the storage modulus (G') at 80°C and loss tangent (tanδ) at 80°C of the buffer layer within the above ranges, the content of the urethane (meth)acrylate in the buffer layer-forming composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, based on the total amount of the buffer layer-forming composition. Furthermore, 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.

[0035] (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 intermediate 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, based on the total amount of the buffer layer-forming composition, 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.

[0036] (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.

[0037] (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.

[0038] (Other ingredients) The buffer layer may contain other components (for example, an antistatic agent, etc.) The other components are not particularly limited and are appropriately selected depending on the purpose.

[0039] (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 onto a release film or a substrate to form a coating film, and this coating film is cured to form an intermediate layer on the substrate. The buffer layer-forming composition may be applied by a known method, for example, a method using various coaters such as an air knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a roll knife coater, a curtain coater, a die coater, a knife coater, a screen coater, a Mayer bar coater, or a kiss coater. In this embodiment, the coating film is preferably cured by irradiation with energy rays, such as 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 irradiated with energy rays while being exposed to oxygen, the coating film may be further irradiated with energy rays while being shielded from oxygen.

[0040] <Protective film forming layer> The protective film forming layer is used to form a protective film on the bump-formed surface of the bumped member. The protective film-forming layer is soft and has high conformability to uneven surfaces such as the bump-formed surface of a bump-equipped member. Furthermore, as described above, by adjusting the storage modulus (G') at 80°C and the loss tangent (tanδ) at 80°C of the buffer layer to fall within specific ranges, the protective film-forming layer exhibits excellent bump penetration and bump embedding properties. The protective film forming layer may be non-curable or curable, but is preferably curable from the viewpoint of improving the protection of the bump forming surface (particularly the protection of the bump base) and from the viewpoint of forming a protective film with excellent protection capabilities such as impact resistance. The protective film forming layer may be a thermosetting layer that is cured by heating, or an energy ray curable layer that is cured by irradiation with energy rays.

[0041] The protective film-forming layer may be a single layer or may be a plurality of layers, such as two or more layers. When the protective film-forming 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.

[0042] The thickness of the protective film-forming layer is not particularly limited, but is preferably 10 to 70 μm, more preferably 15 to 60 μm, and even more preferably 15 to 45 μm. When the thickness of the protective film-forming layer 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 layer is equal to or less than the upper limit, it is possible to prevent the protective film from becoming excessively thick, and it is easy to improve bump penetration properties. The thickness of the protective film forming layer can be adjusted based on the relationship between the thickness of the protective film forming layer and the thickness of the protective film formed by hardening the protective film forming layer, and information such as the height of the bumps on the bumped component to be used. The curable resin film (x) as the protective film-forming layer will be described in detail below.

[0043] (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 bump formation surface (particularly, the protection of the bump neck) and from the viewpoint of forming a protective film with high protection ability, such as excellent impact resistance. The curable resin film (x) may be a thermosetting resin that is cured by heating, or an energy ray curable resin that is cured by irradiation with energy rays. The thermosetting resin film (x1) and the energy ray-curable resin film (x2) will be described below.

[0044] (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.

[0045] -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.

[0046] Examples of the polymer component (A) include acrylic resins, polyarylate resins, polyvinyl acetal, 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 polyvinyl acetals are preferred.

[0047] 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 occurrence of voids between the adherend and the thermosetting resin film. Therefore, the coating property of the bump-forming surface of the semiconductor wafer is improved, and the embedding property into the grooves is also easily improved.

[0048] 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).

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The polyvinyl acetal in the polymer component (A) may be any known polyvinyl acetal. Of these, preferred polyvinyl acetals 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.

[0055] [ka]

[0056] (In the formula, l, m, and n each independently represent an integer of 1 or more.)

[0057] 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 (storage stability) 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 uneven surface of the adherend, which makes it easier to suppress the occurrence of voids between the adherend and the thermosetting resin film (x1). Therefore, the coverage of the bump-forming surface of the semiconductor wafer is improved, and the embedding of grooves is also easily improved.

[0058] 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 film-forming properties of the thermosetting resin film (x1) and protruding properties of the bump tops. Here, in this specification, the term "exposure property of the bump top" refers to the ability of the bump to penetrate the thermosetting resin film (x1) for forming a protective film when the thermosetting resin film (x1) is attached to a wafer with bumps, and is also referred to as the penetration property of the bump top.

[0059] The ratio of the three or more monomers constituting the polyvinyl acetal can be selected arbitrarily.

[0060] The content of the polymer component (A) is preferably 2 to 30 mass %, more preferably 3 to 25 mass %, and even more preferably 3 to 15 mass %, based on the total amount of the active ingredients of the thermosetting resin composition (x1-1).

[0061] 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).

[0062] -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.

[0063] Examples of the thermosetting component (B) include epoxy thermosetting resins, thermosetting polyimides, polyurethanes, unsaturated polyesters, and silicone resins. Among these, epoxy thermosetting resins are preferred. When the thermosetting component (B) is an epoxy thermosetting resin, the protective properties of the cured resin film and the protruding properties of the bump tops can be improved, and warping of the cured resin film can be suppressed.

[0064] 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.

[0065] -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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] The epoxy equivalent of the solid epoxy resin is preferably 150 to 450 g / eq, more preferably 150 to 400 g / eq.

[0070] 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.

[0071] 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.

[0072] -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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 300 to 5,000 parts by mass, even more preferably 400 to 2,000 parts by mass, and even more preferably 500 to 1,000 parts by mass, per 100 parts by mass of the polymer component (A), from the viewpoint of improving the protective properties of the cured resin film.

[0078] -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.

[0079] 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.

[0080] 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).

[0081] -Filling material (D)- The thermosetting resin film (x1) and the thermosetting resin composition (x1-1) may contain a filler (D). The inclusion of the filler (D) makes it easier to adjust the thermal expansion coefficient of the cured resin film obtained by curing the thermosetting resin film (x1) to an appropriate range, thereby further improving the reliability of the package obtained using the thermosetting resin film (x1). Furthermore, the inclusion of the filler (D) in the thermosetting resin film (x1) can also reduce the moisture absorption rate of the cured resin film and improve heat dissipation.

[0082] The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler. Preferred inorganic fillers include, for example, powders of silica, talc, calcium carbonate, boron nitride, etc.; beads obtained by spheronizing these inorganic fillers; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; glass fibers, etc. Among these, the inorganic filler is preferably silica.

[0083] 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.

[0084] When filler (D) is used, the content of 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.

[0085] The average particle size of the filler (D) is preferably from 5 nm to 1000 nm, more preferably from 5 nm to 500 nm, and even more preferably from 10 nm to 300 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.

[0086] -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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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).

[0092] -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).

[0093] 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.

[0094] 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.

[0095] 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).

[0096] -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.

[0097] 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.

[0098] -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.

[0099] -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.

[0100] (Energy ray curable resin film (x2)) The energy ray-curable resin film (x2) contains an energy ray-curable component (a). The energy ray-curable resin film (x2) is formed, for example, from an energy ray-curable resin composition (x2-1) containing an energy ray-curable component (a). The energy ray-curable component (a) is preferably uncured and has adhesive properties, and more preferably is uncured and has adhesive properties. In the following description of this specification, "the content of each component based on the total amount of active ingredients of the energy ray-curable resin composition (x2-1)" is synonymous with "the content of each component of the energy ray-curable resin film (x2) formed from the energy ray-curable resin composition (x2-1)."

[0101] - Energy ray curable component (a) - The energy ray-curable component (a) is a component that is cured by irradiation with energy rays, and is also a component that imparts film-forming properties, flexibility, and the like to the energy ray-curable resin film (x2). Examples of the energy ray-curable component (a) include a polymer (a1) having an energy ray-curable group and a weight-average molecular weight of 80,000 to 2,000,000, and a compound (a2) having an energy ray-curable group and a molecular weight of 100 to 80,000. The polymer (a1) may be at least partially crosslinked with a crosslinking agent, or may not be crosslinked.

[0102] -Polymer (a1)- Examples of the polymer (a1) having an energy ray-curable group and a weight average molecular weight of 80,000 to 2,000,000 include an acrylic resin (a1-1) obtained by polymerizing an acrylic polymer (a11) having a functional group capable of reacting with a group possessed by another compound, and an energy ray-curable compound (a12) having a group reactive with the functional group and an energy ray-curable group such as an energy ray-curable double bond.

[0103] Examples of functional groups that can react with groups possessed by other compounds include hydroxyl groups, carboxyl groups, amino groups, substituted amino groups (groups in which one or two hydrogen atoms of an amino group are substituted with groups other than hydrogen atoms), and epoxy groups. However, from the viewpoint of preventing corrosion of circuits such as semiconductor wafers and semiconductor chips, it is preferable that the functional group be a group other than a carboxyl group. Among these, it is preferable that the functional group be a hydroxyl group.

[0104] Acrylic polymer having functional groups (a11) The acrylic polymer (a11) having a functional group may be, for example, a copolymer of an acrylic monomer having a functional group and an acrylic monomer not having a functional group, or may be a copolymer of these monomers with a monomer other than the acrylic monomer (non-acrylic monomer). The acrylic polymer (a11) may be a random copolymer or a block copolymer.

[0105] Examples of the acrylic monomer having a functional group include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, a substituted amino group-containing monomer, and an epoxy group-containing monomer.

[0106] Examples of hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates 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; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols not having a (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.

[0107] Examples of carboxy group-containing monomers include ethylenically unsaturated monocarboxylic acids (monocarboxylic acids having an ethylenically unsaturated bond) such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids (dicarboxylic acids having an ethylenically unsaturated bond) such as fumaric acid, itaconic acid, maleic acid and citraconic acid; anhydrides of the above ethylenically unsaturated dicarboxylic acids; and (meth)acrylic acid carboxyalkyl esters such as 2-carboxyethyl methacrylate.

[0108] The acrylic monomer having a functional group is preferably a hydroxyl group-containing monomer or a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer.

[0109] The acrylic monomer having a functional group that constitutes the acrylic polymer (a11) may be used alone or in combination of two or more. When the acrylic polymer (a11) contains two or more types of acrylic monomers having a functional group, the combination and ratio thereof can be selected arbitrarily.

[0110] Examples of acrylic monomers having no functional group 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 isopropyl (meth)acrylate. Examples of (meth)acrylic acid alkyl esters include those in which the alkyl group constituting the alkyl ester has a chain structure and has 1 to 18 carbon atoms, such as nonyl, 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).

[0111] Examples of acrylic monomers having no functional group include alkoxyalkyl group-containing (meth)acrylic acid esters such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylic acid esters having an aromatic group, including (meth)acrylic acid aryl esters such as phenyl (meth)acrylate; non-crosslinkable (meth)acrylamide and derivatives thereof; and non-crosslinkable tertiary amino group-containing (meth)acrylic acid esters such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate.

[0112] The acrylic monomer having no functional group that constitutes the acrylic polymer (a11) may be used alone or in combination of two or more. When the acrylic polymer (a11) contains two or more types of acrylic monomers having no functional group, the combination and ratio thereof can be selected arbitrarily.

[0113] Examples of non-acrylic monomers include olefins such as ethylene and norbornene; vinyl acetate; and styrene.

[0114] The non-acrylic monomer constituting the acrylic polymer (a11) may be used singly or in combination of two or more. When the acrylic polymer (a11) is composed of two or more non-acrylic monomers, the combination and ratio thereof can be selected arbitrarily.

[0115] In the acrylic polymer (a11), the proportion (content) of the amount of structural units derived from an acrylic monomer having a functional group relative to the total mass of the structural units constituting the acrylic polymer (a11) is preferably 0.1 to 50 mass%, more preferably 1 to 40 mass%, and even more preferably 3 to 30 mass%. When the proportion is within this range, the content of the energy ray-curable group in the acrylic resin (a1-1) obtained by copolymerization of the acrylic polymer (a11) and the energy ray-curable compound (a12) makes it possible to easily adjust the degree of curing of the protective film (X) within a preferred range.

[0116] The acrylic polymer (a11) constituting the acrylic resin (a1-1) may be used singly or in combination of two or more. When the acrylic polymer (a11) constituting the acrylic resin (a1-1) is two or more types, the combination and ratio thereof can be selected arbitrarily.

[0117] The content of the acrylic resin (a1-1) is preferably 1 to 60 mass %, more preferably 3 to 50 mass %, and even more preferably 5 to 40 mass %, based on the total amount of active ingredients of the energy ray-curable resin composition (x2-1).

[0118] Energy ray curable compounds (a12) The energy ray-curable compound (a12) preferably has one or more groups selected from the group consisting of an isocyanate group, an epoxy group, and a carboxy group as a group reactive with the functional group of the acrylic polymer (a11), and more preferably has an isocyanate group as the group. When the energy ray-curable compound (a12) has, for example, an isocyanate group as the group, this isocyanate group readily reacts with the hydroxyl group of the acrylic polymer (a11) having a hydroxyl group as the functional group.

[0119] The energy ray-curable compound (a12) preferably has 1 to 5 energy ray-curable groups, and more preferably 1 or 2 energy ray-curable groups in one molecule.

[0120] Examples of the energy ray-curable compound (a12) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; and an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate. Among these, the energy ray-curable compound (a12) is preferably 2-methacryloyloxyethyl isocyanate.

[0121] The energy ray-curable compound (a12) constituting the acrylic resin (a1-1) may be used alone or in combination of two or more. When the energy ray-curable compound (a12) constituting the acrylic resin (a1-1) is two or more types, the combination and ratio thereof can be selected arbitrarily.

[0122] In the acrylic resin (a1-1), the ratio of the content of the energy ray-curable groups derived from the energy ray-curable compound (a12) to the content of the functional groups derived from the acrylic polymer (a11) is preferably 20 to 120 mol%, more preferably 35 to 100 mol%, and even more preferably 50 to 100 mol%. When the content is within this range, the adhesive strength of the protective film (X) after curing is increased. When the energy ray-curable compound (a12) is a monofunctional compound (having one such group per molecule), the upper limit of the content is 100 mol%. However, when the energy ray-curable compound (a12) is a polyfunctional compound (having two or more such groups per molecule), the upper limit of the content may exceed 100 mol%.

[0123] The weight average molecular weight (Mw) of the polymer (a1) is preferably from 100,000 to 2,000,000, and more preferably from 300,000 to 1,500,000.

[0124] When the polymer (a1) is at least partially crosslinked with a crosslinking agent, the polymer (a1) may be one which is obtained by polymerizing a monomer which does not correspond to any of the above-mentioned monomers described as constituting the acrylic polymer (a11) and has a group which reacts with the crosslinking agent, and which is crosslinked at the group which reacts with the crosslinking agent, or may be one which is derived from the energy ray-curable compound (a12) and which is crosslinked at a group which reacts with the functional group.

[0125] The polymer (a1) may be used singly or in combination of two or more. When two or more types of polymer (a1) are used, the combination and ratio thereof can be selected arbitrarily.

[0126] -Compound (a2)- The energy ray-curable group contained in the compound (a2) having an energy ray-curable group and a weight average molecular weight of 100 to 80,000 includes a group containing an energy ray-curable double bond, and preferred examples thereof include a (meth)acryloyl group or a vinyl group.

[0127] The compound (a2) is not particularly limited as long as it satisfies the above conditions, and examples thereof include a low-molecular-weight compound having an energy ray-curable group, an epoxy resin having an energy ray-curable group, and a phenolic resin having an energy ray-curable group.

[0128] Among the compounds (a2), examples of low molecular weight compounds having an energy ray-curable group include polyfunctional monomers or oligomers, and acrylate compounds having a (meth)acryloyl group are preferred. Examples of the acrylate compounds include 2-hydroxy-3-(meth)acryloyloxypropyl methacrylate, polyethylene glycol di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-((meth)acryloxydiethoxy)phenyl]propane, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, 2,2-bis[4-((meth)acryloxypolypropoxy)phenyl]propane, tricyclodecane dimethanol di(meth)acrylate, 1,10-decanediol ... bifunctional (meth)acrylates such as 6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2,2-bis[4-((meth)acryloxyethoxy)phenyl]propane, neopentyl glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, and 2-hydroxy-1,3-di(meth)acryloxypropane;Examples of the polyfunctional (meth)acrylates include tris(2-(meth)acryloxyethyl)isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; and polyfunctional (meth)acrylate oligomers such as urethane (meth)acrylate oligomers.

[0129] Of the compounds (a2), examples of epoxy resins having an energy ray-curable group and phenolic resins having an energy ray-curable group that can be used include those described in paragraph 0043 of JP 2013-194102 A.

[0130] The compound (a2) preferably has a weight average molecular weight of 100 to 30,000, more preferably 300 to 10,000.

[0131] The compound (a2) may be used singly or in combination of two or more. When two or more compounds (a2) are used, the combination and ratio thereof can be selected arbitrarily.

[0132] -Polymer (b) having no energy ray-curable group- When the energy ray-curable resin composition (x2-1) and the energy ray-curable resin film (x2) contain the compound (a2) as the energy ray-curable component (a), they preferably further contain a polymer (b) that does not have an energy ray-curable group. The polymer (b) having no energy ray-curable group may be at least partially crosslinked with a crosslinking agent, or may not be crosslinked.

[0133] Examples of the polymer (b) having no energy ray-curable group include acrylic polymers, phenoxy resins, urethane resins, polyesters, rubber-based resins, acrylic urethane resins, and polyvinyl acetals. Among these, the polymer (b) is preferably an acrylic polymer (hereinafter sometimes abbreviated as "acrylic polymer (b-1)") or polyvinyl acetal.

[0134] The acrylic polymer (b-1) may be a known polymer, for example, a homopolymer of one acrylic monomer, or a copolymer of two or more acrylic monomers. Alternatively, the acrylic polymer (b-1) may be a copolymer of one or more acrylic monomers and one or more monomers other than the acrylic monomers (non-acrylic monomers).

[0135] Examples of the acrylic monomer constituting the acrylic polymer (b-1) include (meth)acrylic acid alkyl esters, (meth)acrylic acid esters having a cyclic skeleton, glycidyl group-containing (meth)acrylic acid esters, hydroxyl group-containing (meth)acrylic acid esters, and substituted amino group-containing (meth)acrylic acid esters.

[0136] Examples of (meth)acrylic acid alkyl esters 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 isononyl (meth)acrylate. Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates in which the alkyl group constituting the alkyl ester has a chain structure and has 1 to 18 carbon atoms, such as ethyl (meth)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).

[0137] Examples of (meth)acrylic acid esters having a cyclic skeleton include (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 dicyclopentenyl (meth)acrylate; and (meth)acrylic acid cycloalkenyloxyalkyl esters such as dicyclopentenyloxyethyl (meth)acrylate.

[0138] Examples of the glycidyl group-containing (meth)acrylic acid ester include glycidyl (meth)acrylate, etc. Examples of the hydroxyl group-containing (meth)acrylic acid ester include 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 of the substituted amino group-containing (meth)acrylic acid ester include N-methylaminoethyl (meth)acrylate.

[0139] Examples of non-acrylic monomers that constitute the acrylic polymer (b-1) include olefins such as ethylene and norbornene; vinyl acetate; and styrene.

[0140] As described in the section on polymer component (A), preferred examples of polyvinyl acetal include polyvinyl formal and polyvinyl butyral, with polyvinyl butyral being more preferred. Furthermore, preferred polyvinyl butyrals have structural units represented by the above formulae (i)-1, (i)-2, and (i)-3. Suitable embodiments of polyvinyl butyral are as described for polymer component (A), and therefore further description is omitted.

[0141] The polymer (b) having no energy ray-curable group and at least a portion of which is crosslinked with a crosslinking agent may be, for example, a polymer in which a reactive functional group in the polymer (b) has reacted with a crosslinking agent. The reactive functional group is not particularly limited and may be appropriately selected depending on the type of crosslinking agent, etc. For example, when the crosslinking agent is a polyisocyanate compound, examples of the reactive functional group include a hydroxyl group, a carboxyl group, and an amino group, and among these, a hydroxyl group is preferred because of its high reactivity with an isocyanate group. When the crosslinking agent is an epoxy compound, examples of the reactive functional group include a carboxy group, an amino group, and an amide group, and among these, a carboxy group is preferred because it has high reactivity with an epoxy group. However, from the viewpoint of preventing corrosion of the circuits of semiconductor wafers and semiconductor chips, it is preferable that the reactive functional group is a group other than a carboxy group.

[0142] Examples of the polymer (b) having a reactive functional group but not having an energy ray-curable group include those obtained by polymerizing at least a monomer having a reactive functional group. In the case of the acrylic polymer (b-1), any one or both of the acrylic monomers and non-acrylic monomers listed as the constituent monomers may be used that have a reactive functional group. For example, examples of the polymer (b) having a hydroxyl group as a reactive functional group include those obtained by polymerizing a hydroxyl group-containing (meth)acrylic acid ester, and other examples include those obtained by polymerizing a monomer in which one or more hydrogen atoms in the acrylic monomer or non-acrylic monomer listed above are substituted with the reactive functional group.

[0143] In the polymer (b) having a reactive functional group, the proportion (content) of the amount of the structural units derived from the monomer having a reactive functional group relative to the total mass of the structural units constituting the polymer (b) is preferably 1 to 20 mass%, more preferably 2 to 10 mass%. When the proportion is in this range, the degree of crosslinking in the polymer (b) becomes a more preferable range.

[0144] The weight average molecular weight (Mw) of the polymer (b) having no energy ray-curable group is preferably 10,000 to 2,000,000, and more preferably 20,000 to 1,500,000, in order to improve the film-forming properties of the energy ray-curable resin composition (x2-1).

[0145] The polymer (b) having no energy ray-curable group may be used alone or in combination of two or more. When the polymer (b) having no energy ray-curable group is used in two or more types, the combination and ratio thereof can be selected arbitrarily.

[0146] The energy ray-curable resin composition (x2-1) may contain either or both of a polymer (a1) and a compound (a2). When the energy ray-curable resin composition (x2-1) contains the compound (a2), it preferably further contains a polymer (b) having no energy ray-curable group, and in this case, it is also preferable that it further contains a polymer (a1). Alternatively, the energy ray-curable resin composition (x2-1) may not contain the compound (a2) but may contain both the polymer (a1) and the polymer (b) having no energy ray-curable group.

[0147] When the energy ray-curable resin composition (x2-1) contains the polymer (a1), the compound (a2), and the polymer (b) having no energy ray-curable group, the content of the compound (a2) is preferably 10 to 400 parts by mass, and more preferably 30 to 350 parts by mass, per 100 parts by mass of the total content of the polymer (a1) and the polymer (b) having no energy ray-curable group.

[0148] The total content of the energy ray-curable component (a) and the polymer (b) having no energy ray-curable group is preferably 5 to 90 mass%, more preferably 10 to 80 mass%, and even more preferably 20 to 70 mass%, based on the total amount of active ingredients of the energy ray-curable resin composition (x2-1). When the content of the energy ray-curable component is within this range, the energy ray curability of the energy ray-curable resin film (x2) becomes better.

[0149] The energy ray-curable resin composition (x2-1) may contain, in addition to the energy ray-curable component, one or more selected from the group consisting of a thermosetting component, a photopolymerization initiator, a filler, a coupling agent, a crosslinking agent, and an additive, depending on the purpose. For example, by using an energy ray-curable resin composition (x2-1) containing an energy ray-curable component and a thermosetting component, the adhesive strength of the formed energy ray-curable resin film (x2) to an adherend is improved by heating, and the strength of the protective film (X) formed from this energy ray-curable resin film (x2) is also improved.

[0150] The thermosetting component, photopolymerization initiator, filler, and additive in the energy ray-curable resin composition (x2-1) may be the same as the thermosetting component (B), photopolymerization initiator (F), filler (D), and additive (G) in the energy ray-curable resin composition (x2-1), respectively.

[0151] In the energy ray-curable resin composition (x2-1), the thermosetting component, the photopolymerization initiator, the filler, and the additive may each be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio thereof can be selected arbitrarily. The contents of the thermosetting component, photopolymerization initiator, filler, and additive in the energy ray-curable resin composition (x2-1) may be adjusted appropriately depending on the purpose, and are not particularly limited.

[0152] The energy ray-curable resin composition (x2-1) preferably further contains a solvent, since dilution improves its handling properties. Examples of the solvent contained in the energy ray-curable resin composition (x2-1) include the same solvents as those in the thermosetting resin composition (x1-1). The solvent contained in the energy ray-curable resin composition (x2-1) may be used alone or in combination of two or more. When two or more types are used in combination, the combination and ratio thereof can be selected arbitrarily.

[0153] -Other ingredients- The energy ray-curable resin composition (x2-1) may contain, in addition to the above-described energy ray-curable component, appropriate amounts of components other than the curable component, namely, a curing accelerator (C), a filler (D), an additive (G), etc., as in the case of the thermosetting resin film (x1) described above.

[0154] -Method for preparing energy ray-curable resin composition (x2-1)- The energy ray-curable resin composition (x2-1) can be obtained by blending the components that constitute it. The order in which the components are added when blended 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 ingredients to dilute the ingredients before use, or the solvent may be mixed with any of the other ingredients without pre-diluting them. The method for mixing the ingredients 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 applying 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.

[0155] (Preparation of protective film forming layer) The protective film forming layer of this embodiment can be produced, for example, by applying the protective film forming composition of this embodiment to the surface on which it 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.

[0156] <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 protective film-forming layer. The intermediate release layer is a layer provided for easily peeling the buffer layer from the protective film-forming layer after the composite sheet for forming a protective film is attached to the bump-forming surface of the member with bumps, and the protective film-forming layer is attached to the bump-forming surface.

[0157] 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 (for example, an antistatic agent) in addition to those mentioned above. The other components are not particularly limited and are appropriately selected depending on the purpose.

[0158] 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.

[0159] 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.

[0160] <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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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, softeners (plasticizers), and antistatic agents.

[0165] The substrate may be transparent or opaque, may be colored as desired, or may have other layers vapor-deposited thereon.

[0166] 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.

[0167] <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 protective film forming layer can be produced by the following method. 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 protective film-forming composition of this embodiment is applied to the release-treated surface of a release film, and dried as necessary, to form a protective film-forming layer 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 layer opposite the release film, thereby obtaining a composite sheet for forming a protective film having a laminated structure of the buffer layer and the protective film-forming layer. The release films provided on the protective film forming layer and 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.

[0168] Furthermore, for example, a composite sheet for forming a protective film having a substrate, a buffer layer, and a protective film-forming layer in this order can be produced by the method shown below. A buffer layer is formed on a release film by applying a composition for forming the buffer layer to one side of the substrate and curing it. A first laminate sheet is obtained by laminating the substrate and the buffer layer. 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 protective film-forming composition of this embodiment is applied to the release-treated surface of a release film, and dried as necessary, to form a protective film-forming layer 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 layer opposite the release film, thereby obtaining a composite sheet for forming a protective film having a configuration in which the substrate, buffer layer, protective film-forming layer, and release film are laminated in this order. The release film provided on the protective film forming 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.

[0169] 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.

[0170] [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.

[0171] The method for manufacturing a semiconductor device of this embodiment includes a step of forming a protective film on the bump-forming surface of a bumped member (a bumped semiconductor wafer) using a composite sheet for forming a protective film. More specifically, the method for manufacturing a semiconductor device of this embodiment is preferably a manufacturing method including the following steps 1 to 5. Step 1: A step of laminating the composite sheet for forming a protective film on the semiconductor wafer by attaching the protective film forming layer of the composite sheet for forming a protective film of this embodiment to the bump formation surface of the semiconductor wafer so that the tops of the bumps protrude from the protective film forming layer (hereinafter also referred to as the "attaching step"). Step 2: A step of removing layers other than the protective film forming layer 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 hardening the protective film forming layer on the semiconductor wafer (hereinafter also referred to as the "hardening step"). Step 4: After Step 3, a step of dividing the semiconductor wafer to produce semiconductor chips (hereinafter also referred to as the "dividing step"), and a step of cutting the protective film after Step 3 (hereinafter also referred to as the "cutting 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 1b is used will be described as an example, but it goes without saying that the composite sheet for forming a protective film 1a, 1c, or 1d may also be used.

[0172] <Process 1: Pasting process> FIG. 5 is a schematic cross-sectional view for explaining the bonding step. 5(a) and (b) show a process of attaching a composite sheet 1b for forming a protective film to a bump formation surface 20a of a semiconductor wafer 20. As shown in FIG. In the bonding step, for example, first, the protective film forming composite sheet 1b is placed so that the protective film forming layer 12 faces the bump formation surface 20a of the semiconductor wafer 20 as shown in FIG. 5(a). Next, the protective film forming layer 12 is brought into contact with the bumps 21 on the semiconductor wafer 20, and the composite sheet 1b for forming a protective film is pressed against the semiconductor wafer 20. By pressing, the protective film forming layer 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 protective film forming layer 12 is pressed in through the buffer layer 11, and pressure is applied from the bumps 21, causing tears in the protective film forming layer 12. Ultimately, as shown in FIG. 5(b), the tops of the bumps 21 penetrate the protective film forming layer 12 and protrude. In this embodiment, the storage modulus (G') of the buffer layer 11 at 80°C is 0.08 MPa or more, and the loss tangent (tanδ) of the buffer layer 11 at 80°C is 1.02 or more, so the bump penetration and bump embedding properties of the protective film forming layer 12 can be made good in step 1.

[0173] 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.

[0174] 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.

[0175] 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.

[0176] 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, 60 to 100°C, and preferably 70 to 90°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.

[0177] 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.

[0178] <Step 2: Removal step> FIG. 6 is a schematic cross-sectional view for explaining the removal step. After the bonding process, as shown in Figure 6, all layers of the composite sheet 1b for forming a protective film other than the protective film forming layer 12 are removed to obtain a semiconductor wafer 30 with a protective film forming layer, which comprises a semiconductor wafer 20 and the protective film forming layer 12 provided on the bump forming surface 20a of the semiconductor wafer 20. The layers other than the protective film forming layer 12 can be removed by a known method. In the past, after step 2, special treatments such as plasma treatment were performed to remove resin residue adhering to the top of the bump, but in this embodiment, the protective film forming layer 12 has good bump penetration properties, which has the process advantage of making it possible to omit such special treatments.

[0179] <Process 3: Curing process> FIG. 7 is a schematic cross-sectional view for explaining the curing step. 7, the protective film-forming layer 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 layer are not particularly limited, and may be adjusted and determined as appropriate depending on the type of material constituting the protective film forming layer.

[0180] <Process 4: Splitting process, cutting process> FIG. 8 is a schematic cross-sectional view for explaining the dividing step and the cutting step. After the curing step, as shown in Fig. 8, in a dividing step, the semiconductor wafer 20 is divided to produce semiconductor chips 50. In addition, in a cutting step, the protective film 12' is cut to form a cut protective film 120'. This results in a semiconductor chip 60 with a protective film, which has a cut protective film 120' on the bump-forming surface of the semiconductor chip 50.

[0181] 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).

[0182] <Process 5: Mounting process> In the mounting step, the semiconductor chip 60 with the protective film obtained in the curing step is flip-chip connected to a substrate (not shown) at the tops of the bumps 21. At this time, the semiconductor chip 60 with the protective film is connected to the circuit formation surface of the substrate. In this embodiment, the protective film forming layer 12 has good bump penetration properties, which can prevent resin residue from adhering to the top of the bump. Therefore, good conductivity between the bump and the substrate can be achieved without special treatment such as plasma treatment, and the reliability of the semiconductor device can be improved.

[0183] 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. [Example]

[0184] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0185] [Example 1] (Production Example A1: Preparation of buffer layer A1 for measuring physical properties) A buffer layer-forming composition A1 was obtained by blending 40 parts by mass of aliphatic urethane acrylate 1 (CN966J75 NS, manufactured by Arkema Inc.), 40 parts by mass of isobornyl acrylate (IBXA), and 20 parts by mass of dodecyl acrylate, totaling 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 1.2 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 A1 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 illuminate the buffer layer-forming composition layer 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 above, thereby obtaining a buffer layer A1 having a thickness of 200 μm.

[0186] (Production Example B1: Production of Composite Sheet B1 for Forming Protective Film) (1) Preparation of protective film-forming composition (1-1) Raw materials for the 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.) Epoxy resin (B1) (B1)-1: Liquid modified bisphenol A epoxy resin (DIC Corporation, "Epicron EXA-4850-150", molecular weight 900, epoxy equivalent 450 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 (G) (G)-1: Surfactant (acrylic polymer, BYK "BYK-361N") (G)-2: Silicone oil (aralkyl-modified silicone oil, "XF42-334" manufactured by Momentive Performance Materials Japan)

[0187] (1-2) Preparation of protective film-forming composition Polymer component (A)-1 (100 parts by weight), epoxy resin (B1)-1 (290 parts by weight), epoxy resin (B1)-2 (220 parts by weight), (B2)-1 (160 parts by weight), curing accelerator (C)-1 (2 parts by weight), filler (D)-1 (200 parts by weight), additive (G)-1 (25 parts by weight), and additive (G)-2 (3 parts by weight) were dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to obtain a protective film-forming composition 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.

[0188] (1-3) Production of protective film forming layer A polyethylene multilayer sheet (Gunze Co., Ltd., "Fanclea LLB Type #110", thickness 110 μm) was used as a release film, and the protective film forming composition obtained above was applied to the release-treated surface and dried at 100°C for 2 minutes to produce a 30 μm thick thermosetting protective film forming layer.

[0189] (2) Formation of a buffer layer The buffer layer-forming composition A1 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 200 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. Next, a high-pressure mercury lamp was used to illuminate the buffer layer composition layer 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 above, thereby forming a buffer layer A1 having a thickness of 200 μm. As a result, a laminate sheet (hereinafter also referred to as "first laminate sheet") was obtained in which the substrate, the buffer layer, and the release film were laminated in this order in the thickness direction.

[0190] (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.

[0191] (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.

[0192] (5) Formation of composite sheet for forming protective film The release film was removed from the first laminate sheet obtained above, and the exposed surface of the buffer layer was then bonded to the exposed surface of the intermediate release layer obtained above, thereby obtaining a laminate 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 protective film-forming layer with single-sided release film obtained above was bonded to the exposed surface of the intermediate release layer. In this way, a composite sheet for forming a protective film was obtained, which was composed of a substrate (thickness 75 μm), a buffer layer (thickness 200 μm), an intermediate release layer (thickness 10 μm), and a protective film-forming layer (thickness 30 μm) laminated in this order in the thickness direction.

[0193] [Example 2] (Production Example A2: Preparation of Buffer Layer A2) A buffer layer A2 having a thickness of 200 μm was obtained in the same manner as in Production Example A1 using buffer layer composition A2, which was obtained by changing the amount of chain transfer agent in buffer layer composition A1 to 1.5 parts by mass.

[0194] (Production Example B2: Preparation of Composite Sheet B2 for Protective Film Formation) A composite sheet for forming a protective film B2 was produced in the same manner as in Production Example B1, except that the buffer layer-forming composition A1 was changed to the buffer layer-forming composition A2.

[0195] [Example 3] (Production Example A3: Preparation of Buffer Layer A3) A buffer layer A3 having a thickness of 200 μm was obtained in the same manner as in Production Example A1 using buffer layer composition A3, which was obtained by changing the amount of chain transfer agent in buffer layer composition A1 to 2.0 parts by mass.

[0196] (Production Example B3: Preparation of Composite Sheet B3 for Protective Film Formation) A composite sheet for forming a protective film B3 was produced in the same manner as in Production Example B1, except that the buffer layer-forming composition A1 was changed to the buffer layer-forming composition A3.

[0197] [Comparative Example 1] (Comparative Manufacturing Example A'1: Preparation of Buffer Layer A'1) A buffer layer having a thickness of 200 μm was obtained in the same manner as in Production Example A1 using composition A'1 for forming a buffer layer (photopolymerization initiator 3.0 parts by mass, chain transfer agent 1.2 parts by mass), in which aliphatic urethane acrylate 1 (CN966J75 NS, manufactured by Arkema Inc.) in composition A1 for forming a buffer layer was changed to aliphatic urethane acrylate 2 (CN9021 NS, manufactured by Arkema Inc.), and the amounts of aliphatic urethane acrylate, isobornyl acrylate, and dodecyl acrylate were changed to 30 parts by mass, 30 parts by mass, and 40 parts by mass, respectively (photopolymerization initiator 3.0 parts by mass, chain transfer agent 1.2 parts by mass).

[0198] (Comparative Production Example B'1: Preparation of Composite Sheet B'1 for Forming Protective Film) A composite sheet for forming a protective film B'1 was produced in the same manner as in Production Example B1, except that the buffer layer-forming composition A1 was changed to buffer layer-forming composition A'1.

[0199] Comparative Example 2 (Comparative Manufacturing Example A'2: Preparation of Buffer Layer A'2) A buffer layer having a thickness of 200 μm was obtained using buffer layer forming composition A′2, which was obtained by changing the amount of chain transfer agent in buffer layer forming composition A1 to 0.6 parts by mass, in the same manner as in Production Example A1.

[0200] (Comparative Manufacturing Example B'2: Preparation of Composite Sheet B'2 for Forming Protective Film) A composite sheet for forming a protective film B'2 was produced in the same manner as in Production Example B1, except that the buffer layer-forming composition A1 was changed to the buffer layer-forming composition A'2.

[0201] Comparative Example 3 (Comparative Manufacturing Example A'3: Preparation of Buffer Layer A'3) A buffer layer having a thickness of 200 μm was obtained using buffer layer forming composition A′3, which was obtained by changing the amount of chain transfer agent in buffer layer forming composition A1 to 3.0 parts by mass, in the same manner as in Production Example A1.

[0202] (Comparative Production Example B'3: Preparation of Composite Sheet B'2 for Forming Protective Film) A composite sheet for forming a protective film B'3 was produced in the same manner as in Production Example B1, except that the buffer layer-forming composition A1 was changed to buffer layer-forming composition A'3.

[0203] [evaluation] In this example, the following evaluations 1 to 3 were carried out.

[0204] <Evaluation 1: Measurement of storage modulus G' and loss tangent tanδ of the buffer layer> Samples for measuring the storage modulus and loss tangent of the buffer layers A1 to A3 of Examples 1 to 3 and the buffer layers A'1 to A'3 of Comparative Examples 1 to 3 were prepared. The sample size was 8 mm in diameter and 1 mm in thickness (five 200 μm buffer layers stacked together). The 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 storage modulus G' and loss tangent tanδ at 80°C were calculated.

[0205] <Evaluation 2: Bump embedding ability> After peeling off the PET release film protecting the protective film formation layer of the composite sheets for forming a protective film of Examples 1 to 3 and Comparative Examples 1 to 3, the composite sheets for forming a protective film were attached to the bump formation surface of a semiconductor wafer using an attachment device. The surface of the composite sheet for forming a protective film that was attached to the bump formation surface of the semiconductor wafer was the surface on the protective film formation layer side. The specifications of the semiconductor wafer having bumps are as follows: (Specifications) Wafer size: 8 inches Wafer thickness: 645 μm Bump height: 210 μm Bump width: 250μm Distance between bumps: 400μm The laminating device used was a roller type laminator (manufactured by Lintec Corporation, RAD-3520 F / 12), and lamination was carried out under the following laminating conditions. (Attachment conditions) Table temperature: 90℃ ·Application speed: 3mm / s - Application pressure: 0.5MPa Roller application height: 0μm

[0206] A composite sheet for forming a protective film was attached to the bump-forming surface of a semiconductor wafer having bumps, and then all layers of the composite sheet for forming a protective film other than the protective film forming layer were peeled off from the protective film forming layer.The protective film forming layer was then thermally cured, and the unevenness of the bump-forming surface was observed through the protective film at 100x magnification using a digital microscope (Keyence, VHX-7000).The thermal curing conditions for the protective film forming layer were 130°C and 4 hours.The observation area was 2 cm x 2 cm in the center of the semiconductor wafer. Then, the ratio X of bumps in which bubbles had formed connections with adjacent bumps (called NG bumps) to the total number of bumps in the observation area was calculated. X(%) = {(Number of NG bumps) / (Total number of bumps)} x 100 The evaluation criteria were as follows, with ratings A and B being considered passing. Evaluation A: X is 0%, there is no connection of bubbles, and the bump embedding property is extremely good. · Evaluation B: X is 20% or less, and the bump embedding property is good. · Evaluation C: X is over 20%, and the bump embedding ability is insufficient.

[0207] <Evaluation 3: Evaluation of bump penetration> The sample after evaluation 2 was cut into individual chips, each measuring 5 x 5 mm and containing 144 bumps. Next, bonding to the substrate was carried out using a bonding machine (Toray Engineering "FC-3000W"). (Bonding conditions: load 10N, pressing time 1 second, performed after removing the oxide film on the bump surface using an arbitrary flux agent.) A continuity test was then carried out using a tester (HIOKI's "3244 CARD HiTESTER"). If the continuity was good, it could be said that there was no residue or the like remaining at the top of the bump that would inhibit continuity, and that the bump penetration was good. The evaluation criteria were as follows, with a rating of ◯ being considered a pass. If even one of the 144 bumps has poor conductivity due to residue or the like, the bump is evaluated as x. · Evaluation 〇: Conduction was confirmed with a tester, and the bump penetration was sufficiently good. · Rating ×: Conduction could not be confirmed with a tester, and the bump penetration was insufficient.

[0208] The evaluation results are shown in Table 1.

[0209] [Table 1]

[0210] From Table 1, we can see the following: It is clear that both the bump embeddability and the bump penetration ability are excellent when using the composite sheets for forming a protective film of Examples 1 to 3, in which the buffer layer has a storage modulus of 0.08 MPa or more at 80° C. and a loss tangent of 1.02 or more at 80° C. On the other hand, it is clear that either the bump embeddability or the bump penetration ability is poor in Comparative Examples 1 to 3, in which the buffer layer has a storage modulus of less than 0.08 MPa at 80° C. or a loss tangent of less than 1.02 at 80° C. [Explanation of symbols]

[0211] 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 layer 13 Intermediate peeling layer 20 Semiconductor wafers 20a Bump-forming surface of semiconductor wafer 21 Bump 30 Semiconductor wafer with protective film forming layer 40 Semiconductor wafer with protective film 50 semiconductor chips 60 Semiconductor chip with protective film

Claims

1. A composite sheet for forming a protective film for forming a protective film on a bump-formed surface of a bumped member, It has a laminated structure of a buffer layer and a protective film forming layer, The buffer layer has a storage modulus (G') of 0.08 MPa or more at 80°C, and The composite sheet for forming a protective film, wherein the loss tangent (tan δ) of the buffer layer at 80°C is 1.02 or more.

2. The laminate structure further comprises a substrate, The composite sheet for forming a protective film according to claim 1 , wherein the substrate is laminated on the buffer layer side of the laminated structure.

3. the laminate structure further comprises an intermediate release layer; The composite sheet for forming a protective film according to claim 1 or 2, further comprising an intermediate release layer between the buffer layer and the protective film forming layer.

4. A method for manufacturing a semiconductor device, comprising the step of forming a protective film on a bump-formed surface of a bumped member using the composite sheet for forming a protective film according to claim 1 or 2.

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