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

Abstract

To provide a composite sheet for protective film formation that excels in antistatic properties and also improves workability in semiconductor manufacturing processes.SOLUTION: A composite sheet for protective film formation comprises a substrate, a buffer layer, an intermediate release layer, and a protective film formation layer in that order, and at least one of the buffer layer, the intermediate release layer, and the protective film formation layer contains an antistatic agent.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, semiconductor devices have been manufactured using a mounting method known as the face-down method, in which a semiconductor chip having bumps on its circuit surface and a substrate for mounting the semiconductor chip are stacked together so that the circuit surface of the semiconductor chip faces the substrate, thereby mounting the semiconductor chip on the substrate. The semiconductor chips are usually obtained by dividing a semiconductor wafer having bumps on its circuit surface into individual chips.

[0003] Incidentally, a semiconductor wafer having bumps may be provided with a protective film for the purpose of protecting the bonded portion between the bump and the semiconductor wafer (hereinafter also referred to as a "bump neck"). For example, in Patent Document 1, a laminate in which a base material, an adhesive layer, and a thermosetting resin layer are laminated in this order is pressed and attached to the bump-forming surface of a semiconductor wafer having bumps, with the thermosetting resin layer serving as the bonding surface, and then the thermosetting resin layer is heated and cured to form a protective film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-092594 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been an increasing demand for semiconductor reliability, and in the semiconductor manufacturing process, there has been an increasing demand for suppression of charging in order to prevent damage to circuits formed on semiconductor wafers. Furthermore, in the semiconductor manufacturing process, improvement of workability is a constant challenge.

[0006] Therefore, an object of the present invention is to provide a composite sheet for forming a protective film that has excellent anti-static properties and can improve workability in the semiconductor manufacturing process, and a method for manufacturing a semiconductor device using the composite sheet for forming a protective film. [Means for solving the problem]

[0007] According to the present invention, the following [1] to [6] are provided. [1] A substrate, a buffer layer, an intermediate release layer, and a protective film-forming layer in this order; At least one of the buffer layer, the intermediate release layer, and the protective film-forming layer contains an antistatic agent. [2] The composite sheet for forming a protective film according to [1] above, wherein two or more layers among the buffer layer, the intermediate release layer, and the protective film forming layer contain the antistatic agent. [3] The composite sheet for forming a protective film according to [1] above, wherein all of the buffer layer, the intermediate release layer, and the protective film forming layer contain the antistatic agent. [4] The composite sheet for forming a protective film according to any one of the above [1] to [3], wherein the protective film forming layer is a thermosetting protective film forming layer. [5] The composite sheet for forming a protective film according to any one of the above [1] to [4], wherein the intermediate release layer contains an ethylene-vinyl acetate copolymer. [6] A method for manufacturing a semiconductor device, comprising the step of forming a protective film on a bump-forming surface of a semiconductor wafer using the composite sheet for forming a protective film according to any one of [1] to [5] above. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a composite sheet for forming a protective film that has excellent anti-static properties and can improve workability in the semiconductor manufacturing process, and a method for manufacturing a semiconductor device using the composite sheet for forming a protective film. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example 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 another example of the composite sheet for forming a protective film according to the present embodiment. [Figure 3] 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 4] 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 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. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

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

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

[0015] In this specification, the "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 the circuit side.

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

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

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

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

[0020] [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 has a substrate, a buffer layer, an intermediate release layer, and a protective film-forming layer in this order. At least one of the buffer layer, intermediate release layer, and protective film-forming layer contains an antistatic agent.

[0021] In the composite sheet for forming a protective film of this embodiment, the buffer layer contains an antistatic agent, which (1) imparts antistatic properties to the composite sheet for forming a protective film, and (2) improves workability in the semiconductor manufacturing process, and in particular, (2a) makes it possible to apply the composite sheet for forming a protective film to the bump-forming surface of a semiconductor wafer at higher speeds than before (hereinafter, this will also be simply referred to as "high-speed application ability"). Furthermore, by including an antistatic agent in the intermediate release layer, (1) the composite sheet for forming a protective film is given antistatic properties, and (2) workability in the semiconductor manufacturing process is improved, and in particular, (2b) the releasability of the protective film forming layer (the releasability of the protective film forming layer from layers other than the protective film forming layer) can be improved more than before. Furthermore, by including an antistatic agent in the protective film forming layer, (1) the composite sheet for forming a protective film is given antistatic properties, (2) workability in the semiconductor manufacturing process is improved, and in particular, (2c) the bump penetration ability of the protective film forming layer can be improved compared to conventional methods.

[0022] In the composite sheet for forming a protective film of this embodiment, the antistatic agent may be contained in one of the buffer layer, intermediate release layer, and protective film forming layer, but from the viewpoint of improving the effects of the present invention, it is preferable that the antistatic agent be contained in two of the buffer layer, intermediate release layer, and protective film forming layer (i.e., the buffer layer and intermediate release layer, the buffer layer and protective film forming layer, or the intermediate release layer and protective film forming layer), and it is more preferable that the antistatic agent be contained in all of the buffer layer, intermediate release layer, and protective film forming layer. By including an antistatic agent in the buffer layer and the intermediate release layer, the effect of (1) above is exhibited, and among the effects of (2) above, the effects of (2a) and (2b) above are exhibited. By including an antistatic agent in the buffer layer and the protective film-forming layer, the effect of (1) above is exhibited, and among the effects of (2) above, the effects of (2a) and (2c) above are exhibited. By including an antistatic agent in the intermediate release layer and the protective film-forming layer, the effect of (1) above is exerted, and among the effects of (2) above, the effects of (2b) and (2c) above are exerted. Furthermore, by containing an antistatic agent in all layers, including the buffer layer, intermediate release layer, and protective film forming layer, the effect of (1) above is exerted, and all of the effects of (2a), (2b), and (2c) above are exerted among the effects of (2) above.

[0023] Below, the configuration of the composite sheet for forming a protective film of this embodiment will be explained, followed by details of the antistatic agent, and then details of each layer that constitutes the composite sheet for forming a protective film of this embodiment and a method for manufacturing the composite sheet for forming a protective film will be explained.

[0024] <Configuration of the composite sheet for forming a protective film> The composite sheet for forming a protective film of this embodiment may be formed only from a substrate, a buffer layer, an intermediate release layer, and a protective film forming layer, but may also have layers other than these layers. Examples of such other layers include an adhesion layer for improving adhesion between the substrate and the buffer layer; a release film provided on the surface of the protective film-forming layer opposite the intermediate release layer; and the like. In the composite sheet for forming a protective film that does not have a release film, the protective film forming layer is preferably one of the outermost layers. Furthermore, in the composite sheet for forming a protective film of this embodiment, it is preferable that the substrate and the buffer layer are arranged in direct contact with each other, the buffer layer and the intermediate release layer are arranged in direct contact with each other, and the intermediate release layer and the protective film forming layer are arranged in direct contact with each other.

[0025] FIG. 1 shows an example of the composite sheet for forming a protective film according to this embodiment. The composite sheet 1 for forming a protective film shown in Figure 1 has a substrate 10, a buffer layer 11 laminated on one side 10a of the substrate 10, an intermediate release layer 12 laminated on the side of the buffer layer 11 opposite the substrate 10, and a protective film forming layer 13 laminated on the side of the intermediate release layer 12 opposite the buffer layer 11.

[0026] FIG. 2 shows another example of the composite sheet for forming a protective film according to this embodiment. The composite sheet 2 for forming a protective film shown in Figure 2 has a substrate 10, a buffer layer 11 laminated on one surface 10a of the substrate 10, an intermediate release layer 12 laminated on the surface of the buffer layer 11 opposite the substrate 10, a protective film forming layer 13 laminated on the surface of the intermediate release layer 12 opposite the buffer layer 11, and a release film 14 laminated on the surface of the protective film forming layer 13 opposite the intermediate release layer 12. As the release film, a conventionally known one can be used, and for example, one having a release layer on a release film substrate that has been subjected to a release treatment with a release agent can be mentioned.

[0027] <Antistatic agent> The antistatic agent is not particularly limited as long as it can be kneaded into the resin composition for forming the buffer layer, intermediate release layer, or protective film-forming layer. The antistatic agent may be either a low molecular weight compound or a high molecular weight compound (e.g., an oligomer or a polymer). The antistatic agent may be used alone or in combination of two or more.

[0028] Among the antistatic agents, examples of low molecular weight compounds include ionic liquids, ionic solids, anionic surfactants, alkali metal salts, cationic surfactants, and nonionic surfactants. Among these, from the viewpoint of ease of mixing into the resin composition for forming the buffer layer, intermediate release layer, or protective film forming layer, and from the viewpoint of improving the effects of the present invention, low molecular weight compounds that are liquid at room temperature (23°C) are preferred, and ionic liquids are more preferred. Examples of ionic liquids include pyrimidinium salts, pyridinium salts, piperidinium salts, pyrrolidinium salts, imidazolium salts, alkanolamine salts, morpholinium salts, sulfonium salts, phosphonium salts, and ammonium salts. Commercially available ionic liquids can also be used, including, for example, Aminoion Aminoion AS400 manufactured by Nippon Nyukazai Co., Ltd., Aminoion RE3000MF manufactured by Nippon Nyukazai Co., Ltd., and CIL-R50 manufactured by Nippon Carlit Co., Ltd.

[0029] Among the antistatic agents, examples of polymer compounds include compounds having a quaternary cationic base (preferably a quaternary ammonium base) and a polymer chain (such as an acrylic resin). Commercially available polymer compounds such as this can be used, such as Acrit 8SX-1096JC manufactured by Taisei Fine Chemical Co., Ltd. The mass average molecular weight (Mw) of the polymer compound is preferably 5 million or less, more preferably 2 million or less, and particularly preferably 1 million or less. By setting the molecular weight of the polymer compound within the above range, compatibility with other materials is improved, and surface smoothness is easily improved during film formation.

[0030] As described above, the antistatic agent may be either a low molecular weight compound or a high molecular weight compound (e.g., an oligomer or polymer). However, from the viewpoint of ease of mixing into the resin composition for forming the buffer layer, intermediate release layer, or protective film-forming layer, and from the viewpoint of improving the effects of the present invention, a low molecular weight compound is preferred, a low molecular weight compound that is liquid at room temperature (23°C) is more preferred, and an ionic liquid is even more preferred.

[0031] (Antistatic agent content in buffer layer) The content of the antistatic agent in the buffer layer is preferably more than 0.1 mass%, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, based on the total amount of the buffer layer, from the viewpoint of improving the charge suppression properties of the composite sheet for forming a protective film and improving the high-speed application properties of the composite sheet for forming a protective film to the bump formation surface of a semiconductor wafer. Furthermore, from the viewpoint of easily suppressing bleeding of the buffer layer, the content of the antistatic agent in the buffer layer is preferably 6.5 mass % or less, more preferably 6.0 mass % or less, and even more preferably 5.7 mass % or less, based on the total amount of the buffer layer.

[0032] (Antistatic agent content in intermediate release layer) The content of the antistatic agent in the intermediate release layer is preferably 0.1 mass% or more, more preferably 1.0 mass% or more, and even more preferably 2.0 mass% or more, based on the total amount of the intermediate release layer, from the viewpoint of improving the antistatic properties of the composite sheet for forming a protective film and improving the releasability of the protective film forming layer (releasability of the protective film forming layer from layers other than the protective film forming layer). In addition, in order to prevent excessive improvement in the peelability of the protective film forming layer and to facilitate ensuring the stability of the composite sheet for forming a protective film, the content of the antistatic agent in the intermediate release layer is preferably less than 7.4 mass%, more preferably 6.5 mass% or less, and even more preferably 5.7 mass% or less, based on the total amount of the intermediate release layer.

[0033] (Antistatic Agent Content in Protective Film-Forming Layer) The content of the antistatic agent in the protective film forming layer is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, based on the total amount of the protective film forming layer, from the viewpoint of improving the charge suppression properties of the composite sheet for forming a protective film and improving the bump penetration properties of the protective film forming layer. In addition, from the viewpoint of easily suppressing bleeding of the protective film forming layer, the content of the antistatic agent in the protective film forming layer is preferably 4.8 mass% or less, more preferably 4.3 mass% or less, and even more preferably 3.8 mass% or less, based on the total amount of the protective film forming layer.

[0034] <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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] In addition to the main constituent materials such as the resin, the substrate may contain various known additives such as fillers, colorants, antioxidants, organic lubricants, catalysts, and softeners (plasticizers). The substrate may also contain an antistatic agent.

[0039] The substrate may be transparent or opaque, may be colored as desired, or may have other layers vapor-deposited thereon.

[0040] 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.

[0041] <Buffer layer> The buffer layer is a layer that has a buffering effect against forces applied to the buffer layer and layers directly or indirectly adjacent thereto. Here, the "layers directly or indirectly adjacent to the buffer layer" mainly refer to the intermediate release layer and the protective film-forming layer in this embodiment.

[0042] The buffer layer is in the form of a sheet or film, and the constituent material thereof is not particularly limited. A preferred buffer layer is, for example, one containing urethane (meth)acrylate. The buffer layer may contain components other than the urethane (meth)acrylate. The other components are not particularly limited and are appropriately selected depending on the purpose. The content of the urethane (meth)acrylate in the buffer layer may be 80% by mass or more, or 90% by mass or more.

[0043] 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.

[0044] The thickness of the buffer layer can be adjusted appropriately depending on the height of the bumps to be protected, but from the viewpoint of easily absorbing the effects of relatively tall bumps, it is preferably 150 to 1,000 μm, more preferably 170 to 800 μm, and even more preferably 200 to 600 μm.

[0045] <Intermediate release layer> The intermediate release layer is a layer that is provided to easily release the buffer layer and substrate from the protective film forming layer after adhering the protective film forming layer to the bump forming surface of the semiconductor wafer by attaching the composite sheet for protective film formation to the bump forming surface.

[0046] The intermediate release layer is in the form of a sheet or film, and the material constituting the layer is not particularly limited. The intermediate release layer preferably comprises ethylene-vinyl acetate copolymer (EVA). The intermediate release layer may contain other components in addition to those described above. The other components are not particularly limited and are appropriately selected depending on the purpose. The content of EVA in the intermediate release layer may be 80% by mass or more, or may be 90% by mass or more.

[0047] 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.

[0048] 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.

[0049] <Protective film forming layer> The protective film forming layer is used to form a protective film on the bump formation surface of a semiconductor wafer. The protective film forming layer is soft and has high conformability to uneven surfaces such as the bump-formed surface of a semiconductor wafer, and therefore exhibits high adhesion to uneven surfaces such as the bump-formed surface of a semiconductor wafer. 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 formation surface (particularly the protection of the bump neck) and from the viewpoint of forming a protective film with excellent protection capabilities such as impact resistance. The protective film forming layer may be thermosetting, that is, cured by heating, or energy ray-curable, that is, cured by energy ray irradiation, but is preferably thermosetting from the viewpoint of improving handleability. The thickness of the protective film-forming layer is not particularly limited, but is preferably 1 to 200 μm, more preferably 10 to 150 μm, and even more preferably 20 to 130 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 tends to prevent the protective film from becoming excessively thick, and it is easy to prevent an increase in residue on the top of the bump.

[0050] Hereinafter, each component contained in the thermosetting protective film-forming layer (resin composition for forming a protective film-forming layer) will be described in detail.

[0051] (Polymer component (A)) The polymer component (A) is a component for imparting film-forming properties and flexibility to the protective film-forming layer formed from the resin composition for the protective film-forming layer. The polymer component (A) may be used alone or in combination of two or more.

[0052] Examples of the polymer component (A) include polyvinyl acetal resin, acrylic resin, polyester resin, urethane resin, phenoxy resin, silicone resin, etc. Among these, one or more resins selected from the group consisting of polyvinyl acetal resin, acrylic resin, and polyester resin are preferred, and polyvinyl acetal resin is more preferred.

[0053] -Polyvinyl acetal resin- Examples of polyvinyl acetal resins include known ones, and polyvinyl formal and polyvinyl butyral are preferred, with polyvinyl butyral being more preferred. The polyvinyl butyral is preferably one having a constitutional unit represented by the following formula (i)-1, a constitutional unit represented by the following formula (i)-2, and a constitutional unit represented by the following formula (i)-3.

[0054] [ka] (In the formula, l, m, and n each independently represent an integer of 1 or more.)

[0055] The mass average molecular weight (Mw) of the polyvinyl acetal resin is not particularly limited, but is preferably 5,000 to 200,000, and more preferably 8,000 to 100,000. When the mass average molecular weight (Mw) of the polyvinyl acetal resin is equal to or greater than the lower limit, the shape stability (stability over time during storage) of the protective film forming layer tends to be better. Also, when the mass average molecular weight (Mw) of the polyvinyl acetal resin is equal to or less than the upper limit, the protective film forming layer tends to conform better to the irregularities on the bump-forming surface of the semiconductor wafer, and the occurrence of voids between the semiconductor wafer and the protective film forming layer tends to be more easily suppressed.

[0056] The glass transition temperature (Tg) of the polyvinyl acetal resin is not particularly limited, but is preferably 40 to 80°C, more preferably 50 to 70°C, from the viewpoint of the application and handling properties of the protective film-forming layer.

[0057] The ratio of the three or more monomers constituting the polyvinyl acetal resin can be selected arbitrarily.

[0058] -Acrylic resin- As the acrylic resin, a known acrylic polymer can be used. The mass average molecular weight (Mw) of the acrylic resin is not particularly limited, but 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 mass average molecular weight (Mw) of the acrylic resin is equal to or greater than the lower limit, the shape stability (stability over time during storage) of the protective film forming layer tends to be better. Also, when the mass average molecular weight (Mw) of the acrylic resin is equal to or less than the upper limit, the protective film forming layer tends to conform better to the irregularities on the bump-forming surface of the semiconductor wafer, and the occurrence of voids between the semiconductor wafer and the protective film forming layer tends to be more easily suppressed.

[0059] The glass transition temperature (Tg) of the acrylic resin is not particularly limited, but is preferably from -50 to 70°C, more preferably from -30 to 60°C, from the viewpoint of the application and handling properties of the protective film-forming layer.

[0060] Examples of the monomer that constitutes the acrylic resin include (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, etc. Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates in which the alkyl group constituting the alkyl ester is linear and has 1 to 18 carbon atoms; (meth)acrylates having a cyclic skeleton such as benzyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and imide (meth)acrylate; hydroxyl group-containing (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; glycidyl group-containing (meth)acrylates such as glycidyl (meth)acrylate; and substituted amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate. Here, the term "substituted amino group" refers to a group having a structure in which one or two hydrogen atoms of an amino group have been substituted with a group other than a hydrogen atom. The acrylic resin may also be a copolymer of a monomer other than a (meth)acrylic acid ester, such as acrylic acid, methacrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, or N-methylolacrylamide. The acrylic resin may be made up of one kind of monomer or two or more kinds of monomers.

[0061] The acrylic resin may have a functional group, such as a vinyl group, a (meth)acryloyl group, an amino group, a hydroxy group, a carboxy group, an isocyanate group, or a glycidyl group. When the acrylic resin has a functional group, the functional group may be bonded to another compound, for example, via a crosslinking agent described below, or may be bonded directly to another compound without the use of a crosslinking agent.

[0062] -Polyester resin- Examples of polyester resins include known polyester resins, such as resins whose basic structure is polycondensation of polyol and polycarboxylic acid. Examples of polyols include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol; alicyclic diols such as cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A; and aromatic diols such as bisphenol A, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A. Among these, aromatic diols are preferred. Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; and anhydrides thereof. Among these, aromatic dicarboxylic acids are preferred. The polyols and polycarboxylic acids may each be used alone or in combination of two or more. Among the polyester resins, polyarylate resins are preferred. Examples of polyarylate resins include known resins, such as resins based on the polycondensation of a dihydric phenol and a dibasic acid such as phthalic acid or carboxylic acid. Among these, polycondensates of bisphenol A and phthalic acid, poly(4,4'-isopropylidenediphenylene terephthalate / isophthalate) copolymers, and derivatives thereof are preferred.

[0063] -Content of polymer component (A)- In this embodiment, the content of polymer component (A) in the resin composition for the protective film forming layer is not particularly limited, but is preferably 2 to 30 mass %, more preferably 5 to 20 mass %, and even more preferably 7 to 12 mass %, relative to the total amount (100 mass %) of the solid content of the resin composition for the protective film forming layer excluding the inorganic filler. When the content of the polymer component (A) is within the above range, the film-forming properties and flexibility of the protective film-forming layer, as well as the impact resistance of the protective film, tend to be better.

[0064] (Thermosetting component (B)) In this embodiment, the resin composition for protective film-forming layer contains the thermosetting component (B), and thus has thermosetting properties, making it possible to form a hard protective film. The thermosetting component (B) may be used alone or in combination of two or more kinds.

[0065] Examples of the thermosetting component (B) include epoxy resin (B1), phenolic resin, melamine resin, urea resin, and thermosetting polyimide resin. Among these, epoxy resin (B1) is preferred. When the thermosetting component (B) contains epoxy resin (B1), the protective properties of the protective film and the protruding properties of the bump tops can be improved, and warping of the protective film can be suppressed.

[0066] In this embodiment, the resin composition for protective film-forming layer preferably contains, as the thermosetting component (B), an epoxy resin (B1) and a thermosetting agent (B2).

[0067] -Epoxy resin (B1)- Examples of the epoxy resin (B1) include known epoxy resins, such as bisphenol A epoxy resins and bisphenol F epoxy resins, and hydrogenated versions thereof; novolac epoxy resins such as phenol novolac epoxy resins, cresol novolac epoxy resins, and orthocresol novolac epoxy resins; aralkyl epoxy resins such as phenol aralkyl epoxy resins; dicyclopentadiene epoxy resins; biphenyl epoxy resins; naphthalene epoxy resins; anthracene epoxy resins; fluorene skeleton epoxy resins; trisphenol epoxy resins; etc. Among these, bisphenol A epoxy resins and dicyclopentadiene epoxy resins are preferred.

[0068] The number average molecular weight (Mn) of the epoxy resin (B1) is not particularly limited, but from the viewpoint of the curability of the protective film-forming layer and the strength and heat resistance of the protective film, it is preferably 300 to 30,000, more preferably 400 to 10,000, and even more preferably 500 to 3,000.

[0069] The epoxy equivalent of the epoxy resin (B1) is not particularly limited, but is preferably 100 to 1,000 g / eq, more preferably 120 to 800 g / eq, and even more preferably 150 to 500 g / eq. In this specification, the term "epoxy equivalent" means the number of grams (g / eq) of an epoxy resin containing 1 gram equivalent of epoxy groups, and can be measured according to JIS K 7236:2001.

[0070] -Thermal hardener (B2)- The heat curing agent (B2) is a component that functions as a curing agent for the epoxy resin (B1). The heat curing agent (B2) may be used alone or in combination of two or more kinds.

[0071] Examples of the heat curing agent (B2) include compounds having two or more functional groups capable of reacting with epoxy groups in one molecule. Examples of functional groups that can react with epoxy groups include phenolic hydroxyl groups, alcoholic hydroxyl groups, amino groups, carboxyl groups, and groups in which acid groups have been anhydridized. Among these, phenolic hydroxyl groups are preferred. Hereinafter, a heat curing agent (B2) having a phenolic hydroxyl group will be referred to as a "phenolic curing agent."

[0072] Examples of phenol-based curing agents include polyfunctional phenols, biphenols, novolac-type phenols, dicyclopentadiene-type phenols, aralkyl-type phenols, etc. Among these, novolac-type phenols are preferred, and O-cresol novolac is more preferred. Examples of amine-based curing agents having an amino group include dicyandiamide.

[0073] In this embodiment, when the resin composition for the protective film forming layer contains a thermosetting agent (B2), the content of the thermosetting agent (B2) in the resin composition for the protective film forming layer is not particularly limited, but is preferably 1 to 200 parts by mass, more preferably 5 to 100 parts by mass, and even more preferably 10 to 50 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 lower limit, the curing of the protective film-forming layer tends to proceed more easily. On the other hand, when the content of the thermosetting agent (B2) is equal to or less than the upper limit, the moisture absorption rate is reduced, and the reliability of the semiconductor device including the protective film-forming layer (protective film) tends to be further improved.

[0074] In the resin composition for the protective film forming layer of this embodiment, the content of the thermosetting component (B) is not particularly limited, but is preferably 200 to 3,000 parts by mass, more preferably 300 to 2,000 parts by mass, even more preferably 400 to 1,500 parts by mass, still more preferably 500 to 1,000 parts by mass, and particularly preferably 650 to 800 parts by mass, per 100 parts by mass of the polymer component (A). When the content of the thermosetting component (B) is equal to or less than the above upper limit, a protective film with better protective ability tends to be formed.

[0075] (Curing accelerator (C)) In this embodiment, the resin composition for a protective film-forming layer may further contain a curing accelerator (C). The curing accelerator (C) is a component for adjusting the curing rate of the protective film-forming layer. The curing accelerator (C) may be used alone or in combination of two or more kinds.

[0076] 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.

[0077] When the resin composition for the protective film forming layer contains a curing accelerator (C), the content of the curing accelerator (C) in the resin composition for the protective film forming layer is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and even more preferably 1 to 3 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 lower limit, the effects of using the curing accelerator (C) tend to be more pronounced. On the other hand, when the content of the curing accelerator (C) is equal to or less than the upper limit, for example, the effect of suppressing the highly polar curing accelerator (C) from migrating to the adhesive interface with the adherend and segregating under high temperature and high humidity conditions is enhanced, and the reliability of the semiconductor device obtained using the resin composition for protective film-forming layer tends to be further improved.

[0078] (Filling material (D)) The resin composition for a protective film-forming layer of this embodiment may further contain a filler (D). By including filler (D) in the resin composition for the protective film forming layer of this embodiment, it becomes easier to adjust the thermal expansion coefficient of the protective film within an appropriate range, and the reliability of the package obtained using the resin composition for the protective film forming layer of this embodiment tends to be further improved. Furthermore, by including the filler (D) in the resin composition for a protective film-forming layer of this embodiment, it is possible to reduce the moisture absorption rate of the protective film and improve the heat dissipation properties. The filler (D) may be used alone or in combination of two or more kinds.

[0079] The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler. Examples of inorganic fillers include powders of silica, alumina, talc, calcium carbonate, red iron oxide, silicon carbide, 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, silica and alumina are preferred from the viewpoint of making it easier to exhibit the effects of the present invention.

[0080] The average particle size of the filler (D) is not particularly limited, but is preferably 5 nm to 1,000 nm, more preferably 5 nm to 500 nm, and even more preferably 10 nm to 300 nm. The above average particle diameter is the average value of the outer diameter of one particle measured at several points.

[0081] When the resin composition for the protective film forming layer contains a filler (D), the content of the filler (D) in the resin composition for the protective film forming layer is not particularly limited, but from the viewpoint of suppressing peeling of the protective film from the chip due to thermal expansion and thermal contraction, it is preferably 2 to 30 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 10 to 20 parts by mass per 100 parts by mass of the total amount of the solid components of the resin composition for the protective film forming layer excluding the inorganic filler.

[0082] (Other ingredients (E)) The resin composition for a protective film-forming layer of this embodiment may contain other components (E) in addition to the above components, as long as the effects of the present invention are not impaired. The other components (E) may be known and may be selected arbitrarily depending on the purpose, and are not particularly limited. Examples of other components (E) include crosslinking agents such as polymer component (A), surface conditioners such as silicone oil, coupling agents, surfactants, plasticizers, antioxidants, gettering agents, and the like. The other component (E) may be used alone or in combination of two or more. The content of the other component (E) is not particularly limited and may be appropriately selected depending on the purpose.

[0083] (solvent) The resin composition for a protective film-forming layer of this embodiment may further contain a solvent from the viewpoint of improving handleability. The solvent may be used alone or in combination of two or more kinds. Examples of the solvent 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; amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone; etc. Among these, methyl ethyl ketone is preferred from the viewpoint of ease of uniformly mixing the components.

[0084] (Method for preparing a resin composition for a protective film-forming layer) The resin composition for a protective film-forming layer of this embodiment can be produced by blending the above-mentioned components. The order of addition of the components when blending is not particularly limited, and two or more components may be added simultaneously. 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, stirring blades, etc.; 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 may be adjusted appropriately depending on the type of component used, but a temperature of 15 to 30°C is preferred.

[0085] (Preparation of protective film forming layer) The protective film forming layer of this embodiment can be produced, for example, by applying the resin composition for a protective film forming layer of this embodiment to the surface on which it is to be formed, and drying it as necessary. The resin composition for the protective film forming layer 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, Meyer bar coater, or kiss coater. The drying conditions after applying the resin composition for the protective film-forming layer 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.

[0086] <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, which has a substrate, a buffer layer, an intermediate release layer, and a protective film-forming layer in this order, can be produced by the method shown below. A composition for forming a buffer layer is applied to one surface of a substrate and dried as needed to obtain a first laminate sheet in which the substrate and the buffer layer are laminated together. If necessary, a release film may be provided on the surface of the buffer layer in the first laminate sheet opposite the substrate. Separately, a composition for forming an intermediate release layer is applied to the release-treated surface of the release film, and dried as necessary, to form an intermediate release layer on the release film. Separately, the resin composition for a protective film forming layer 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.

[0087] Next, the exposed surface of the buffer layer in the first laminate sheet opposite the substrate is bonded to the exposed surface of the intermediate release layer opposite the release film, thereby obtaining a second laminate sheet having a configuration in which the substrate, buffer layer, intermediate release layer, and release film are laminated in this order.

[0088] Next, the release film is removed from the second laminate sheet, and the exposed surface of the intermediate release layer 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, intermediate release 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.

[0089] 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.

[0090] <Physical properties of composite sheet for forming protective film> The composite sheet for forming a protective film of the present embodiment preferably satisfies the following physical properties.

[0091] (Surface resistivity) The composite sheet for forming a protective film of the present embodiment preferably has a surface resistivity of 3.5×10 as measured by the method described in the examples below. 14 Ω / □ or less, more preferably 1.0×10 14 Ω / □ or less, more preferably 5.0×10 13 Ω / □ or less, particularly preferably 1.0×10 13 It is Ω / □ or less. It can be said that the smaller the surface resistivity, the more excellent the anti-static property of the composite sheet for forming a protective film.

[0092] (peel force) The composite sheet for forming a protective film of this embodiment preferably has a peel strength of 5.0 N / mm or less, more preferably 3.0 N / 25 mm or less, and even more preferably 1.8 N / 25 mm or less, measured by the method described in the examples below. The smaller the peeling force, the easier it is to peel the buffer layer and substrate from the protective film forming layer of the composite sheet for forming a protective film.

[0093] (Amount of seepage) The composite sheet for forming a protective film of this embodiment preferably has an exudation amount of 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less, as measured by the method described in the examples below. The smaller the amount of seepage, the more excellent the long-term stability of the composite sheet for forming a protective film.

[0094] [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.

[0095] 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 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.

[0096] <Process 1: Pasting process> FIG. 3 is a schematic cross-sectional view for explaining the bonding step. 3(a) and (b) show a process of attaching the composite sheet 1 for forming a protective film to the bump formation surface 20a of the semiconductor wafer 20. As shown in FIG. In the bonding step, for example, first, the composite sheet 1 for forming a protective film is placed so that the protective film formation layer 13 faces the bump formation surface 20a of the semiconductor wafer 20 as shown in FIG. 3(a). Next, the protective film forming layer 13 is brought into contact with the bumps 21 on the semiconductor wafer 20, and the composite sheet 1 for forming a protective film is pressed against the semiconductor wafer 20. By pressing, the protective film forming layer 13 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 13 is pressed in through the buffer layer 11, and pressure is applied from the bumps 21, causing tears in the protective film forming layer 13. Ultimately, as shown in FIG. 3(b), the tops of the bumps 21 penetrate the protective film forming layer 13 and protrude. When the protective film forming layer 13 of the composite sheet 1 for forming a protective film contains an antistatic agent, the penetration property of the bumps 21 is improved. Therefore, the workability when penetrating and protruding the upper portions of the bumps 21 from the protective film forming layer 13 (the workability of step 1) is improved.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] The composite sheet 1 for forming a protective film can be pressure-bonded to the semiconductor wafer 20 by any known method for pressing and attaching various sheets to an object, such as a method using a roller laminator. The heating temperature when the composite sheet 1 for forming a protective film is pressure-bonded to the semiconductor wafer 20 is not particularly limited, and may be, for example, 80 to 100°C, and preferably 85 to 95°C. The pressure when the composite sheet for forming a protective film 1 is pressure-bonded to the semiconductor wafer 20 is not particularly limited, and may be, for example, 0.1 to 1.5 MPa, and preferably 0.3 to 1 MPa. The speed at which the composite sheet 1 for forming a protective film is attached to the semiconductor wafer 20 is not particularly limited, and is usually about 2 mm / s. When the buffer layer 10 of the composite sheet 1 for forming a protective film contains an antistatic agent, it can have excellent high-speed application properties. Therefore, the speed at which the composite sheet 1 for forming a protective film is applied to the semiconductor wafer 20 can be improved. Specifically, the speed can be improved to preferably 5 mm / s or more, more preferably 5 mm / s to 10 mm / s, thereby improving the workability at which the composite sheet 1 for forming a protective film is applied to the semiconductor wafer 20 (the workability of step 1).

[0101] 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.

[0102] <Step 2: Removal step> FIG. 4 is a schematic cross-sectional view for explaining the removal step. After the bonding process, as shown in Figure 4, all layers of the composite sheet 1 for forming a protective film except the protective film forming layer 13 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 13 provided on the bump forming surface 20a of the semiconductor wafer 20. The layers other than the protective film forming layer 13 can be removed by a known method. Here, when the intermediate release layer 12 of the composite sheet 1 for forming a protective film contains an antistatic agent, the peelability is improved when peeling layers other than the protective film forming layer 13 from the protective film forming layer 13 of the composite sheet 1 for forming a protective film. Therefore, the workability in step 2 is improved.

[0103] <Process 3: Curing process> FIG. 5 is a schematic cross-sectional view for explaining the curing step. 5, the protective film forming layer 13 is thermally cured to form a protective film 13' on the bump formation surface 20a of the semiconductor wafer 20. This results in a protective film-coated semiconductor wafer 40 having the protective film 13' on the bump formation 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.

[0104] <Process 4: Splitting process, cutting process> FIG. 6 is a schematic cross-sectional view for explaining the dividing step and the cutting step. After the curing step, as shown in Fig. 6, in a dividing step, the semiconductor wafer 20 is divided to produce semiconductor chips 50. In addition, in a cutting step, the protective film 13' is cut to form a cut protective film 130'. This results in a semiconductor chip 60 with a protective film, which has a cut protective film 130' on the bump-forming surface of the semiconductor chip 50.

[0105] 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 13' 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).

[0106] <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.

[0107] 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]

[0108] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0109] [Method for measuring mass average molecular weight (Mw)] The method for measuring the mass average molecular weight (Mw) in the present examples is as follows. Measurement was carried out using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8320GPC") under the following conditions, and the values ​​measured were converted into standard polystyrene equivalents. (Measurement conditions) Column: "TSKgel guardcolumn SuperHzH", "TSKgel SuperHZM-M", "TSKgel SuperHZM-M", "TSKgel SuperHZ2000" (all manufactured by Tosoh Corporation) connected in series Column temperature: 40℃ Developing solvent: tetrahydrofuran Standard material: Polystyrene Injection volume: 20 μL Flow rate: 0.35 mL / min Detector: Differential refractometer

[0110] [Examples 1 to 16, Comparative Example 1] Composite sheets for forming a protective film of Examples 1 to 16 and Comparative Example 1 were prepared with different layers containing an antistatic agent, different types of antistatic agents, and different amounts of antistatic agents added, and were evaluated as described below. The composite sheet for forming a protective film of Comparative Example 1 was a composite sheet for forming a protective film in which none of the layers contained an antistatic agent. In the composite sheets for forming a protective film of Examples 1 to 7, only the buffer layer contained an antistatic agent. In the composite sheets for forming a protective film of Examples 8 to 11, only the intermediate release layer contained an antistatic agent. In the composite sheets for forming a protective film of Examples 12 and 13, only the protective film-forming layer contained an antistatic agent. The composite sheet for forming a protective film of Example 14 contained an antistatic agent only in two layers, the buffer layer and the intermediate release layer. The composite sheet for forming a protective film of Example 15 contained an antistatic agent only in two layers, the intermediate release layer and the protective film-forming layer. The composite sheet for forming a protective film of Example 16 was a composite sheet for forming a protective film in which all three layers, namely the buffer layer, the intermediate release layer, and the protective film-forming layer, contained an antistatic agent. Details of the layer containing the antistatic agent, the type of the antistatic agent, and the amount of the antistatic agent added are as shown in Table 2.

[0111] <Antistatic agent type> Table 1 shows the details of the antistatic agents A to D used in this example. As shown in Table 1, all of the antistatic agents are liquid at room temperature (23°C).

[0112] [Table 1]

[0113] In this example, in order to produce a composite sheet for forming a protective film having a layer structure as shown in Table 2, predetermined amounts of predetermined antistatic agents A to D were blended into the resin composition for the buffer layer prepared in the "Preparation of substrate with buffer layer" described below, the resin composition for the protective film forming layer prepared in the "Preparation of protective film forming layer" and the resin composition for the intermediate release layer prepared in the "Preparation of intermediate release layer". The amount of antistatic agent added (unit: parts by mass) shown in Table 2 means the amount of antistatic agent added when the amount of the solid content of the resin composition for the buffer layer, the resin composition for the protective film forming layer, or the resin composition for the intermediate release layer excluding the antistatic agent is taken as 100 parts by mass. In addition, the amount of antistatic agent added (unit: mass %) shown in Table 2 means the amount of antistatic agent added based on the total solid content (100 mass %) of the resin composition for the buffer layer, the resin composition for the protective film forming layer, or the resin composition for the intermediate release layer.

[0114] <Preparation of substrate with buffer layer> A resin composition for a buffer layer was prepared by blending 40 parts by mass of monofunctional urethane acrylate, 45 parts by mass of isobornyl acrylate (IBXA), 15 parts by mass of 2-hydroxypropyl acrylate (HPA), 3.5 parts by mass of pentaerythritol tetrakis(3-mercaptobutyrate) (Showa Denko K.K., product name "KARENZMT (registered trademark) PE1", a secondary tetrafunctional thiol-containing compound, solids concentration 100% by mass), 1.8 parts by mass of a crosslinker, and 1.0 part by mass of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (BASF, product name "Darocur (registered trademark) 1173", solids concentration 100% by mass) as a photopolymerization initiator. This resin composition for a buffer layer was applied to a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4300", thickness 75 μm) to form a coating film, and then ultraviolet light was irradiated from the coating film side to form a semi-cured layer. The ultraviolet irradiation was performed using a belt conveyor type ultraviolet irradiation device (manufactured by iGraphics Co., Ltd., product name "ECS-401GGX") as the ultraviolet irradiation device, a high-pressure mercury lamp (manufactured by iGraphics Co., Ltd., product name "H04-L41") as the ultraviolet source, and irradiation conditions were a light wavelength of 365 nm and an illuminance of 120 mW / cm. 2 , light intensity 200mJ / cm 2 The measurement was carried out under the conditions of (measured using a UVPF-A1 product manufactured by iGraphics Co., Ltd.). A polyethylene terephthalate (PET) release film (manufactured by Lintec Corporation, product name SP-PET381031), one side of which was treated with silicone for release, was laminated onto the formed semi-cured layer, and further ultraviolet light was irradiated from the PET release film side (using the above-mentioned ultraviolet light irradiation device and ultraviolet light source, with an illuminance of 330 mW / cm). 2 , light intensity 1,200mJ / cm 2 ) and completely cured to form a buffer layer with a thickness of 400 μm on the PET film as the substrate, thereby obtaining a substrate with a buffer layer.

[0115] <Preparation of protective film forming layer> (raw materials) (1) Polymer component (A) Polyvinyl butyral having a structural unit represented by the following formula (i)-1, a structural unit represented by the following formula (i)-2, and a structural unit represented by the following formula (i)-3 (manufactured by Sekisui Chemical Co., Ltd., product name "S-LEC BL-10", mass average molecular weight (Mw) 25,000, glass transition temperature 59°C)

[0116] [ka] (wherein l1 is approximately 28, m1 is 1 to 3, and n1 is an integer of 68 to 74.)

[0117] (2) Epoxy resin (B1) (B1)-1: Liquid modified bisphenol A epoxy resin (manufactured by DIC Corporation, product name "Epiclon EXA-4850-150", number average molecular weight (Mn) 900, epoxy equivalent 450 g / eq) (B1)-2: Dicyclopentadiene-type epoxy resin (manufactured by DIC Corporation, product name "HP-7200HH", epoxy equivalent 254 to 264 g / eq)

[0118] (3) Heat curing agent (B2) (B2)-1: O-cresol novolac resin (manufactured by DIC Corporation, product name "Phenolite KA-1160")

[0119] (4) Curing accelerator (C) (C)-1:2-Phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Corporation, product name "Curezol 2PHZ-PW")

[0120] (5) Filler (D) (D)-1: Spherical silica modified with epoxy groups (manufactured by Admatechs Co., Ltd., product name "Admanano YA050C-MKK", average particle size 50 nm)

[0121] (6) Additives (E) (E)-1: Surfactant (acrylic polymer, manufactured by BYK, product name "BYK-361N") (E)-2: Silicone oil (aralkyl-modified silicone oil, manufactured by Momentive Performance Materials Japan, product name "XF42-334")

[0122] (Preparation of Resin Composition for Protective Film-Forming Layer) Polymer component (A)-1 (100 parts by mass), epoxy resin (B1)-1 (290 parts by mass), epoxy resin (B1)-2 (220 parts by mass), heat curing agent (B2)-1 (160 parts by mass), curing accelerator (C)-1 (2 parts by mass), filler (D)-1 (200 parts by mass), additive (E)-1 (25 parts by mass), and additive (E)-2 (3 parts by mass) were dissolved or dispersed in methyl ethyl ketone and stirred at 23 ° C. to obtain a resin composition for protective film-forming layers with a total concentration of all components other than the solvent of 45% by mass. Note that the amounts of all components other than the solvent shown here do not include the solvent.

[0123] (Preparation of protective film forming layer) The resin composition for the protective film forming layer obtained above was applied to the release-treated surface of a PET-based release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm), and then heated and dried at 120°C for 2 minutes to form a protective film forming layer 30 μm thick on the PET-based release film.

[0124] <Preparation of intermediate release layer> An ethylene-vinyl acetate copolymer (EVA, mass average molecular weight 55,000, content of structural units derived from vinyl acetate 20% by mass) was dissolved in toluene at room temperature to prepare a resin composition for an intermediate release layer with a solids concentration of 12% by mass. The resin composition for an intermediate release layer was then coated onto the release-treated surface of a PET release film ("SP-PET381031" manufactured by Lintec Corporation, thickness 38 μm) and dried by heating at 100°C for 2 minutes to form an intermediate release layer with a thickness of 10 μm on the PET release film.

[0125] <Preparation of composite sheet for forming protective film> The PET release film was peeled off from the buffer layer-attached substrate, and an intermediate release layer was attached to the exposed surface. The PET release film from the intermediate release layer was then peeled off, and a protective film-forming layer was attached to the exposed surface, producing a composite sheet for forming a protective film. The laminate structure of the composite sheet for forming a protective film is as follows: ·Base material / Buffer layer / Intermediate release layer / Protective film forming layer / PET release film

[0126] [evaluation] In this example, the following evaluations 1 to 5 were carried out.

[0127] <Evaluation 1: Electrostatic discharge (ESD) evaluation> Using the composite sheets for forming a protective film of Examples 1 to 16 and Comparative Example 1, square samples of 10 cm x 10 cm were prepared, and the surface resistivity of the square samples was measured using a DIGITAL ELECTROMETER (manufactured by ADVANTEST, product name "R8252-TR42"). The applied voltage during measurement was 100 V. It can be said that the smaller the surface resistivity, the better the charge suppression property. The evaluation criteria were as follows: In this example, the evaluations ◯ and △ were considered to be acceptable. Evaluation: Surface resistivity is 1.0 x 10 14 Smaller than Ω / □. △: Surface resistivity is 1.0×10 14 Ω / □ or more 3.5×10 14 It is Ω / □ or less. Rating ×: Surface resistivity is 3.5×10 14 Greater than Ω / □.

[0128] <Evaluation 2: Evaluation of peeling force> After peeling off the PET release film protecting the protective film forming layer from the composite sheets for forming a protective film of Examples 1 to 16 and Comparative Example 1, the composite sheets for forming a protective film were attached to the mirror surface of a silicon wafer using an attachment device. The surface of the composite sheet for forming a protective film to be attached to the silicon wafer was the surface on the protective film forming layer side. 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. (Conditions for application) Table temperature: 80℃ Application speed: 5mm / s - Application pressure: 0.1MPa Roller application height: 0 μm After that, a sample was cut to a width of 25 mm, and the silicon wafer was fixed to a universal tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon UTM-4-100") Next, the layers other than the protective film forming layer (the intermediate release layer, buffer layer, and substrate) were pulled from the protective film forming layer in a 180° direction at a pulling rate of 300 mm / min in accordance with JIS Z0237:2009 under conditions of a temperature of 23°C and 50% RH, and the force when the layers other than the protective film forming layer (the intermediate release layer, buffer layer, and substrate) were peeled from the protective film forming composite sheet fixed to the silicon wafer, leaving only the protective film forming layer, was measured, and this was taken as the peel force (unit: N / 25 mm). The evaluation criteria were as follows: In this example, the evaluations ◯ and △ were considered to be acceptable. · Evaluation 〇: Peeling force is less than 1.8N / 25mm. · Evaluation △: Peeling force is 1.8N / 25mm or more and 5.0N / mm or less. · Evaluation ×: Peeling force is greater than 5.0 N / 25 mm or peeling is not possible.

[0129] <Evaluation 3: Evaluation of high-speed application> After peeling off the PET release film protecting the protective film forming layer of the composite sheet for forming a protective film in Examples 1 to 16 and Comparative Example 1, the composite sheet for forming a protective film was attached to the bump formation surface of a semiconductor wafer having bumps 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 having bumps was the surface on the protective film forming layer side. The specifications of the semiconductor wafer having bumps are as follows: (Specifications) Wafer size: 8 inches Wafer thickness: 645μm Bump height: 210 μm Bump width: 250μm Distance between bumps: 400μm The lamination was performed using a roller laminator (RAD-3520 F / 12, manufactured by Lintec Corporation) under the following lamination conditions: The lamination speed is generally set to about 2 mm / s, and the lamination speed in this example was more than twice as fast as the general conditions. (Attachment conditions) Table temperature: 80℃ Application speed: 5mm / s - Application pressure: 0.1MPa Roller application height: 0 μm

[0130] A composite sheet for forming a protective film was attached to the bump-forming surface of a semiconductor wafer having bumps, and then the 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. The evaluation criteria were as follows: In this example, a rating of ◯ and a rating of △ were considered to be acceptable. · Evaluation: No air bubbles were generated between the bump formation surface and the protective film, and the unevenness caused by the bumps was filled in. · Evaluation △: Although there are a few air bubbles between the bump formation surface and the protective film, the unevenness caused by the bumps is filled in without any problems. · Evaluation ×: The unevenness caused by the bumps could not be filled in, and the protective film floated above the bump formation surface.

[0131] <Evaluation 4: Evaluation of top of head residue> For some of the samples after evaluation 3, the tops of the bumps were observed using a field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation "S-4700") to check the exposed state of the bumps at the tops of the bumps and the residues originating from the protective film forming layer. The evaluation criteria were as follows: In this example, a rating of ◯ was considered to be acceptable. ·Rating: Bump The bump on the top of the head is at least partially exposed. · Evaluation ×: The top of the bump is not exposed, and the protective film forming layer remains on the bump (the protective film forming layer covers the bump, and the bump is not exposed at all).

[0132] <Evaluation 5: Evaluation of bleeding> The composite sheets for forming a protective film of Examples 1 to 16 and Comparative Example 1 were cut into 3 cm squares and left to stand at 40°C for 7 days with a load of 2 kg applied. After that, the load was released at room temperature (23°C), and the sheet was visually inspected for bleeding. The amount of bleeding was measured with a ruler for any bleeding that had occurred. The smaller the amount of bleeding, the more excellent the long-term stability of the composite sheet for forming a protective film.

[0133] The evaluation results are shown in Table 2.

[0134] [Table 2]

[0135] From Table 2, we can see the following: The results shown in Examples 1 to 16 show that by including an antistatic agent in any of the buffer layer, intermediate release layer, and protective film forming layer, a composite sheet for forming a protective film can be obtained that has excellent anti-static properties and can improve workability in the manufacturing process of a semiconductor device. In detail, the results shown in Examples 1 to 7, 14, and 16 show that by including an antistatic agent in the buffer layer, a composite sheet for forming a protective film can be obtained that has excellent antistatic properties and high-speed application properties. Furthermore, the results shown in Examples 8 to 11 and Examples 14 to 16 show that by including an antistatic agent in the intermediate release layer, a composite sheet for forming a protective film can be obtained that has excellent antistatic properties and excellent releasability of the protective film-forming layer. From the viewpoint of improving the releasability of the protective film-forming layer, it is also found that, as in Example 14, it is preferable that the intermediate release layer contains an antistatic agent while the content of the antistatic agent in the protective film-forming layer is low. Furthermore, the results shown in Examples 12 to 13, Example 15, and Example 16 show that by including an antistatic agent in the protective film forming layer, a composite sheet for forming a protective film can be obtained that has excellent antistatic properties and reduces top residue (in other words, has excellent bump penetration properties). [Explanation of symbols]

[0136] 1, 2 Composite sheet for forming protective film 10 Base material 10a One side of the substrate 11 Buffer layer 12 Intermediate peeling layer 13 Protective film forming layer 14 Release film 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. The substrate has a substrate, a buffer layer, an intermediate release layer, and a protective film-forming layer in this order; At least one of the buffer layer, the intermediate release layer, and the protective film-forming layer contains an antistatic agent.

2. The composite sheet for forming a protective film according to claim 1 , wherein two or more layers selected from the buffer layer, the intermediate release layer, and the protective film-forming layer contain the antistatic agent.

3. The composite sheet for forming a protective film according to claim 1 , wherein all of the buffer layer, the intermediate release layer, and the protective film-forming layer contain the antistatic agent.

4. 4. The composite sheet for forming a protective film according to claim 1, wherein the protective film forming layer is a thermosetting protective film forming layer.

5. 4. The composite sheet for forming a protective film according to claim 1, wherein the intermediate release layer contains an ethylene-vinyl acetate copolymer.

6. A method for manufacturing a semiconductor device, comprising the step of forming a protective film on a bump-forming surface of a semiconductor wafer using the composite sheet for forming a protective film according to any one of claims 1 to 3.

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