TW202539909A - Composite sheet for forming protective film and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention provides a composite sheet for forming a protective film with excellent electrostatic suppression and improved workability in semiconductor manufacturing processes. The composite sheet for forming a protective film of the present invention sequentially comprises a substrate, a buffer layer and a protective film forming layer, wherein at least one of the aforementioned buffer layer and the aforementioned protective film forming layer contains an antistatic agent.

Description

Method for manufacturing composite thin film and semiconductor device for protective film formation

This invention relates to a method for manufacturing a composite sheet for forming a protective film and a semiconductor device.

In recent years, semiconductor devices have been manufactured using a method known as face-down mounting. In face-down mounting, a semiconductor chip with bumps on its electrical surfaces and a substrate for mounting the semiconductor chip are laminated with the electrical surfaces of the semiconductor chip facing each other, thereby mounting the semiconductor chip onto the substrate. Furthermore, the semiconductor chip is typically obtained by monolithically mounting a semiconductor wafer with bumps on its electrical surfaces.

Incidentally, for the purpose of protecting the bonding area between the bumps and the semiconductor wafer (hereinafter also referred to as the "bump neck"), a protective film is sometimes applied to semiconductor wafers with bumps. For example, in Patent 1, a laminate consisting of a substrate, an adhesive layer, and a thermosetting resin layer is sequentially stacked, with the thermosetting resin layer as the bonding surface. This laminate is then pressed onto the bump-forming surface of the semiconductor wafer with bumps and attached. The thermosetting resin layer is then heated and hardened to form a protective film. [Prior Art Documents][Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2015-092594

[Problem to be Solved by the Invention] In recent years, the requirements for the reliability of semiconductors have been continuously increasing. In the semiconductor manufacturing process, based on the viewpoint of suppressing circuit damage formed on semiconductor wafers, the requirements for electrostatic discharge (ESD) suppression have also been continuously increasing. Furthermore, improving workability is a frequently requested issue in the semiconductor manufacturing process.

Therefore, the present invention provides a composite wafer for forming a protective film with excellent electrostatic discharge suppression and improved workability in semiconductor manufacturing processes, and a method for manufacturing a semiconductor device using the composite wafer for forming the protective film. [Means for solving the problem]

According to the present invention, the following are provided [1] to [6]. [1] A composite sheet for forming a protective film, characterized in that it sequentially comprises a substrate, a buffer layer and a protective film forming layer, wherein at least one of the buffer layer and the protective film forming layer contains an antistatic agent. [2] The composite sheet for forming a protective film as described above [1], wherein both the buffer layer and the protective film forming layer contain the aforementioned antistatic agent. [3] The composite sheet for forming a protective film as described above [1] or [2], wherein an intermediate peeling layer is further provided between the buffer layer and the protective film forming layer. [4] The composite sheet for forming a protective film as described in [3] above, wherein the intermediate release layer contains an ethylene-vinyl acetate copolymer. [5] The composite sheet for forming a protective film as described in any one of [1] to [4] above, wherein the protective film forming layer is a thermosetting protective film forming layer. [6] A method for manufacturing a semiconductor device, characterized by comprising: forming a protective film on a bump forming surface of a semiconductor wafer using the composite sheet for forming a protective film as described in any one of [1] to [5] above. [Invention Effects]

According to the present invention, a composite sheet for forming a protective film with excellent electrostatic suppression and improved workability in semiconductor manufacturing steps is provided, as well as a method for manufacturing a semiconductor device using the composite sheet for forming a protective film.

In this specification, the mass average molecular weight (Mw) and number average molecular weight (Mn) are standard polystyrene conversion values determined by gel osmosis chromatography (GPC), specifically values determined based on the method described in the embodiments.

In this manual, the lower and upper limits of the preferred numerical ranges (such as the range of content) can be combined independently. For example, based on the statement "preferably 10~90, more preferably 30~60", the "preferable lower limit (10)" and the "preferable upper limit (60)" can be combined to form "10~60".

The term "energy beam" in this manual refers to those containing energy quanta within electromagnetic waves or beams of charged particles. Examples of energy beams include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be emitted using electrodeless lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, black lamps, and LED lights. Electron beams can be emitted by electron beam accelerators or similar devices.

In this manual, "energy line hardening property" refers to the property of hardening due to exposure to energy lines. Furthermore, in this manual, "thermal hardening property" refers to the property of hardening due to heating, and "non-hardening property" refers to the property of hardening without being heated or exposed to energy lines.

In this manual, for example, the term "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid," and other similar terms are used in the same way.

In this specification, the "surface surface" of a semiconductor wafer and semiconductor chip refers to the side on which the circuit is formed, and the "back side" of a semiconductor wafer and semiconductor chip refers to the side opposite to the surface surface.

The term "thickness" for an object as used in this manual refers to the total thickness of the object. For example, if the object is composed of multiple layers, it refers to the total thickness of all the layers constituting the object. Furthermore, unless otherwise specified, the term "thickness" for an object as used in this manual refers to the average thickness measured at five randomly selected locations on the object, which can be obtained using a constant pressure thickness gauge according to JIS K 7130.

The term "solid components" in this instruction manual refers to the components contained in the object composition, excluding diluents such as water and organic solvents.

The mechanism of action described in this specification is speculative and is not a mechanism that limits the effectiveness of this invention.

To facilitate understanding of the features of this invention, important parts are sometimes enlarged in the drawings, and the dimensions and proportions of the components may not be the same as in reality.

[Appearance of the composite sheet for forming a protective film according to this embodiment] The composite sheet for forming a protective film according to this embodiment sequentially comprises a substrate, a buffer layer and a protective film forming layer. Moreover, at least one of the buffer layer and the protective film forming layer contains an antistatic agent.

In the protective film forming composite sheet of this embodiment, because the buffer layer contains an antistatic agent, it can (1) impart static electricity suppression properties to the protective film forming composite sheet and (2) improve the workability of semiconductor manufacturing steps. In particular, (2-1) the protective film forming composite sheet can be attached to the bump forming surface of the semiconductor wafer at a higher speed than before (hereinafter also referred to as "high-speed attachment"). Furthermore, because the protective film forming layer contains an antistatic agent, it (1) imparts static electricity suppression properties to the protective film forming composite sheet and (2) improves the workability of semiconductor manufacturing steps. In particular, (2-2) the bump penetration of the protective film forming layer can be improved more than before.

In the composite sheet for forming the protective film of this embodiment, the antistatic agent may be contained in one of the buffer layer and the protective film forming layer, but from the viewpoint of improving the effect of the present invention, it is more preferably contained in both the buffer layer and the protective film forming layer. By containing the antistatic agent in the buffer layer and the protective film forming layer, the effect of (1) above is achieved, and the effects of (2-1) and (2-2) above are also achieved.

The following section explains the composition of the composite sheet for forming the protective film of this embodiment, followed by a description of the details of the antistatic agent. Next, the details of each layer of the composite sheet for forming the protective film of this embodiment and the manufacturing method of the composite sheet for forming the protective film will be explained.

<Composition of the Composite Sheet for Forming Protective Film> The composite sheet for forming protective film of this embodiment may be formed only of a substrate, a buffer layer, and a protective film forming layer, but may also have other layers besides these layers. Examples of such other layers include, for example, an adhesion layer for improving the adhesion between the substrate and the buffer layer; a release film disposed on the surface of the protective film forming layer opposite to the substrate; an intermediate release layer disposed between the buffer layer and the protective film forming layer; etc. Furthermore, in a composite sheet for forming protective film that does not have a release film, the protective film forming layer is preferably the outermost layer. Furthermore, in the composite sheet for forming the protective film of this embodiment, the substrate and the buffer layer can be in direct contact, and the buffer layer and the protective film forming layer can also be in direct contact. Based on the viewpoint of improving the peelability of the substrate and the buffer layer and the protective film forming layer (in other words, the viewpoint of improving the peelability of the buffer layer and the protective film forming layer), an intermediate peeling layer can also be provided between the buffer layer and the protective film forming layer.

Figure 1 shows an example of a 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 deposited on one side 10a of the substrate 10, and a protective film forming layer 12 deposited on the side of the buffer layer 11 opposite to the substrate 10.

Figure 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 deposited on one side 10a of the substrate 10, a protective film forming layer 12 deposited on the side of the buffer layer 11 opposite to the substrate 10, and a release film 13 deposited on the side of the protective film forming layer 12 opposite to the buffer layer 11. As a release film, conventionally known materials can be used, for example, a release layer on a substrate for a release film that has been treated with a release agent for peeling.

<Antistatic Agent> As an antistatic agent, there are no particular limitations as long as it can be blended into resin compositions used to form a buffer layer or protective film forming layer. Furthermore, the antistatic agent can be either a low-molecular-weight compound or a high-molecular-weight compound (e.g., oligomers or polymers). An antistatic agent can be used alone or in combination with two or more other agents.

Among 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, based on the viewpoints of ease of incorporation into resin compositions used to form buffer layers or protective film layers, and to improve the effectiveness of the present invention, low-molecular-weight compounds that are liquid at room temperature (23°C) are preferred, and ionic liquids are even more preferred. Examples of ionic liquids include pyrimidineonium salts, pyridinium salts, piperidinium salts, pyrrolidineonium salts, imidazoonium salts, alkanolamine salts, morpholinium salts, strontium salts, phosphonium salts, and ammonium salts. Commercially available products can also be used as ionic liquids. Examples include Nippon Emulsifiers Co., Ltd.'s AS400 ionic liquid, Nippon Emulsifiers Co., Ltd.'s RE3000MF ionic liquid, and Carlit Corporation of Japan's CIL-R50 ionic liquid.

Antistatic agents include, for example, compounds containing a fourth-order cation exchange base (preferably a fourth-order ammonium alkali) and a polymer chain (such as acrylic resins). Commercially available products can also be used as such polymers. An example is Acrylit 8SX-1096JC manufactured by Taishin Precision Chemical Co., Ltd. The mass-average molecular weight (Mw) of the polymer 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 within the above range, it exhibits good compatibility with other materials, making it easier to improve surface smoothness during film formation.

As mentioned above, the antistatic agent can be either a low molecular weight compound or a high molecular weight compound (e.g., an oligomer or a polymer), but based on the viewpoint of ease of incorporation into the resin composition used to form a buffer layer or a protective film forming layer, and the viewpoint of improving the effect of the present invention, it is preferred to be a low molecular weight compound, more preferably a low molecular weight compound that is a liquid at room temperature (23°C), and even more preferably an ionic liquid.

(Antistatic agent content in the buffer layer) Based on the viewpoint of improving the static electricity suppression of the composite sheet for forming the protective film and improving the high-speed adhesion of the composite sheet for forming the protective film to the bump formation surface of the semiconductor wafer, the antistatic agent content in the buffer layer, based on the total amount of the buffer layer, preferably exceeds 0.1% by mass, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, based on the viewpoint that it is easy to suppress the seepage of the buffer layer, the content of antistatic agent in the buffer layer, based on the total amount of the buffer layer, is preferably 6.5% by mass or less, more preferably 6.0% by mass or less, and even more preferably 5.7% by mass or less.

(Antistatic agent content in the protective film forming layer) Based on the viewpoints of improving the static electricity suppression of the composite sheet for forming the protective film and improving the protrusion penetration of the protective film forming layer, the antistatic agent content in the protective film forming layer, based on the total amount of the protective film forming layer, is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more. Furthermore, based on the viewpoint of easily suppressing the seepage of the protective film forming layer, the antistatic agent content in the protective film forming layer, based on the total amount of the protective film forming layer, is preferably 4.8% by mass or less, more preferably 4.3% by mass or less, and even more preferably 3.8% by mass or less.

<Substrate> The substrate is in sheet or film form, and examples of its constituent materials include the following resins. Examples of resins constituting the substrate include polyethylene 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 resins; ethylene-based copolymers (copolymers obtained using ethylene as a monomer) such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-(meth)acrylate copolymer, and ethylene-norbornene copolymer; and polyethylene such as polyvinyl chloride and vinyl chloride copolymer. Resins (resins obtained using vinyl chloride as a monomer); polystyrene; polycyclic cyclohexene; polyethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, polyethylene isophthalate, polyethylene 2,6-naphthalate, and polyesters of all aromatic polyesters whose constituent units have aromatic cyclic groups; copolymers of two or more of the above polyesters; poly(meth)acrylate; polyurethane; polyurethane acrylate; polyimide; polyamide; polycarbonate; fluororesins; polyacetal; modified polyphenylene ether; polyphenylene sulfide; polyetherketone; etc. Examples of resins used as the constituent base material include polymer alloys such as mixtures of the above polyesters and other resins. The polymer alloy of the aforementioned polyester and other resins is preferably one in which the amount of resin other than polyester is relatively small. Furthermore, the resin used as the constituent base material can be, for example, one or more cross-linked resins of the resins described above as currently illustrated; or modified resins using one or more ionomers of the resins described above as currently illustrated. One type of resin can be used alone, or two or more types can be used in combination as the constituent base material.

The substrate may be a single layer or multiple layers, including two or more layers. When the substrate is multiple layers, these multiple layers may be identical or different from each other, and there are no particular restrictions on the combination of these multiple layers.

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

The substrate is preferably one with high thickness accuracy, that is, thickness deviation is suppressed regardless of the location. Among the above-mentioned constituent materials, examples of such materials with high thickness accuracy that can be used to form the substrate are, for example, polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyesters other than polyethylene terephthalate and polybutylene terephthalate, ethylene-vinyl acetate copolymers, etc.

In addition to the main constituent materials such as resins mentioned above, the substrate may also contain various known additives such as fillers, colorants, antioxidants, organic lubricants, catalysts, and plasticizers. Furthermore, the substrate may also contain antistatic agents.

The substrate can be transparent or opaque, and can be colored or coated with other layers depending on the purpose.

The substrate can be manufactured by known methods. For example, a resin-containing substrate can be manufactured by molding a resin composition containing the aforementioned resin.

<Buffer Layer> A buffer layer is a layer that has a buffering effect on the force applied to the layer directly or indirectly adjacent to the buffer layer. Here, "the layer directly or indirectly adjacent to the buffer layer" mainly refers to the protective film forming layer of this embodiment.

The cushioning layer may be in the form of a sheet or film, and its constituent materials are not particularly limited. Preferred cushioning layers include, for example, those containing urethane (meth)acrylates. The cushioning layer may also contain other components besides urethane (meth)acrylates. These other components are not particularly limited and can be appropriately selected according to the purpose. The content of urethane (meth)acrylates in the cushioning layer may be 80% by mass or more, or even 90% by mass or more.

A buffer layer can be a single layer or multiple layers, including two or more. When there are multiple buffer layers, these multiple layers can be the same as each other or different from each other, and there are no particular restrictions on the combination of these multiple layers.

The thickness of the buffer layer can be appropriately adjusted according to the height of the bumps to be protected, but based on the view that it can also easily absorb the influence of bumps with higher heights, it is preferably 150~1,000μm, more preferably 170~800μm, and even more preferably 200~600μm.

<Intermediate Peel-Off Layer> As described above, in the protective film forming composite sheet of this embodiment, an intermediate peel-off layer can also be provided between the buffer layer and the protective film forming layer. The intermediate peel-off layer is a layer provided after the protective film forming composite sheet is attached to the bump forming surface of the semiconductor wafer, so that the protective film forming layer is closely attached to the bump forming surface, in order to facilitate the peeling of the buffer layer and the substrate from the protective film forming layer.

The intermediate release layer can be in the form of a sheet or a film, and its constituent materials are not particularly limited. Preferably, the intermediate release layer contains ethylene-vinyl acetate copolymer (EVA). The intermediate release layer may also contain other components besides those mentioned above. These other components are not particularly limited and can be selected appropriately according to the purpose. The EVA content in the intermediate release layer can be 80% by mass or more, or even 90% by mass or more.

The intermediate peeling layer can be a single layer or multiple layers, including two or more. When there are multiple intermediate peeling layers, these multiple layers can be the same as each other or different from each other, and there are no particular restrictions on the combination of these multiple layers.

The thickness of the intermediate exfoliating layer is not particularly limited, but it is preferably 5~30μm, more preferably 6~25μm, and even more preferably 7~20μm.

<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 highly conforms to the uneven surfaces of the semiconductor wafer, such as the bump formation surface. Therefore, the protective film forming layer exhibits high adhesion to the uneven surfaces of the semiconductor wafer, such as the bump formation surface. The protective film forming layer can be non-hardened or hardened, but based on the viewpoint of improving the protection of the bump formation surface (especially the protection of the bump neck) and forming a protective film with superior shock resistance, a hardened type is preferred. Furthermore, the protective film forming layer can be thermosetting (cured by heating) or energy-curing (cured by energy beam irradiation), but thermosetting is preferred from the perspective of improving treatment efficiency. The thickness of the protective film forming layer is not particularly limited, but is preferably 1-200 μm, more preferably 10-150 μm, and even more preferably 20-130 μm. If the thickness of the protective film forming layer is above the lower limit mentioned above, it is easier to produce thin sheets with high in-plane uniformity, and there is a tendency to form a protective film with higher protective performance. Moreover, if the thickness of the protective film forming layer is below the upper limit mentioned above, there is a tendency to suppress excessively thick protective films, and it is easier to suppress the accumulation of residue on the top of the bump.

The following is a detailed explanation of the components contained in thermosetting protective film cambium (a resin composition used to form a protective film cambium).

(Polymer Component (A)) Polymer Component (A) is a component used to impart film-forming properties and flexibility to the protective film forming layer formed by the resin composition of the protective film forming layer. Polymer Component (A) may be used alone or in combination with two or more.

Examples of polymer component (A) include, for example, polyvinyl acetal resin, acrylic resin, polyester resin, carbamate resin, phenoxy resin, and silicone resin. Preferably, it is selected from one or more of the group consisting of polyvinyl acetal resin, acrylic resin, and polyester resin, and more preferably, it is polyvinyl acetal resin.

-Polyvinyl acetal resin- Polyvinyl acetal resins, such as those known, are preferably polyethylene formaldehyde, polyethylene butyral, and more preferably polyethylene butyral. Polyvinyl butyral is preferably one having constituent units represented by formula (i)-1, formula (i)-2, and formula (i)-3 below.

(In the formula, l, m and n are each an integer greater than or equal to 1).

The mass average molecular weight (Mw) of the polyvinyl acetal resin is not particularly limited, but it 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 above the lower limit mentioned above, the shape stability (stability over time during storage) of the protective film layer tends to be better. Furthermore, when the mass average molecular weight (Mw) of the polyvinyl acetal resin is below the upper limit mentioned above, the tracking of the unevenness of the bump formation surface of the semiconductor wafer becomes better, and there is a tendency to easily suppress the generation of voids between the resin and the semiconductor wafer.

The glass transition temperature (Tg) of polyvinyl acetal resin is not particularly limited, but from the perspective of the adhesion and treatment of the protective film forming layer, it is preferably 40~80℃, and more preferably 50~70℃.

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

-Acrylic Resin- Known acrylic polymers can be used as acrylic resins. 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 above the lower limit mentioned above, there is a tendency for better morphological stability (stability over time during storage) of the protective film layer. Furthermore, when the mass average molecular weight (Mw) of the acrylic resin is below the upper limit mentioned above, there is better conformability to the bump formation surface of the semiconductor wafer, and a tendency to easily suppress the generation of voids between the acrylic resin and the semiconductor wafer.

The glass transition temperature (Tg) of acrylic resin is not particularly limited, but based on the viewpoint of the adhesion and treatment of the protective film forming layer, it is preferably -50~70℃, and more preferably -30~60℃.

Examples of monomers constituting acrylic resins include, for example, (meth)acrylates. Examples of (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, terbutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, 2-ethylhexyl (meth)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, heptadecanyl (meth)acrylate, decadecyl (meth)acrylate, etc. Alkyl esters such as octaalkyl esters, in which the alkyl group is chain-like and has 1 to 18 carbon atoms, are (meth)acrylates; benzyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenoxyethyl (meth)acrylate, amide (meth)acrylate, and other (meth)acrylates with a cyclic skeleton, such as hydroxymethyl (meth)acrylate and 2-hydroxymethyl (meth)acrylate. Acrylic resins include hydroxyl-containing (meth)acrylates such as methyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate; glycidyl methacrylate and other (meth)acrylates containing glycidyl groups; and N-methylaminoethyl methacrylate and other (meth)acrylates containing substituted amino groups. Here, "substituted amino group" refers to a group having one or two hydrogen atoms of an amino group substituted with a group other than a hydrogen atom. Furthermore, acrylic resins can also copolymerize monomers other than (meth)acrylates, such as acrylic acid, methacrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-hydroxymethylacrylamide. The monomers constituting acrylic resins can be one type or two or more types.

Acrylic resins may have functional groups. Examples of such functional groups include vinyl, (meth)acrylic, amino, hydroxyl, carboxyl, isocyanate, and glycidyl groups. When acrylic resins have functional groups, these functional groups may bond with other compounds through, for example, a crosslinking agent described later, or they may bond directly with other compounds without the intervention of a crosslinking agent.

-Polyester Resins- Examples of known polyester resins include resins whose basic structure is the polycondensation of polyols and polycarboxylic acids. 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, cyclohexanediol, and bisphenol A hydrogenated; and aromatic diols such as bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts 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, carboxylic acid, itaconic acid, glutaric acid, succinic acid, alkenyl succinic 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 their anhydrides. Among these, aromatic dicarboxylic acids are preferred. Regarding polyols and polycarboxylic acids, one type may be used alone, or two or more may be used in combination. Among polyester resins, polyarylate resins are preferred. Examples of known polyarylate resins include, for example, resins whose basic structure is the polycondensation of divalent phenols with dicarboxylic acids such as phthalic acid and carboxylic acids. Among these, preferred are polycondensates of bisphenol A and phthalic acid, poly(4,4'-isopropylidene diphenyl terephthalate/isophthalate copolymers, and derivatives thereof.

-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 it is preferably 2-30% by mass, more preferably 5-20% by mass, and even more preferably 7-12% by mass, relative to the total amount of components excluding inorganic fillers in the solid portion of the resin composition for the protective film forming layer. When the content of polymer component (A) is within the above range, there is a tendency for the protective film forming layer to have better film-forming properties, flexibility, and impact resistance.

(Thermosetting component (B)) In this embodiment, the protective film forming layer resin composition becomes thermosetting by containing thermosetting component (B) and can form a hard protective film. Thermosetting component (B) can be used alone or in combination with two or more.

Examples of thermosetting components (B) include epoxy resins (B1), phenolic resins, melamine resins, urea resins, and thermosetting polyimide resins. Among these, epoxy resin (B1) is preferred. When epoxy resin (B1) is included as a thermosetting component (B), the protective properties of the protective film and the protrusion of the bump top can be improved, and the warping of the protective film can be suppressed.

In this embodiment, the protective film forming layer is a resin composition, which, as a thermosetting component (B), preferably contains an epoxy resin (B1) and a thermosetting agent (B2).

-Epoxy Resins (B1)- Examples of known epoxy resins (B1) include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, and their hydrogenates; phenolic varnish type epoxy resins, cresol phenolic varnish type epoxy resins, and ortho-cresol phenolic varnish type epoxy resins. Phenolic varnish-type epoxy resins, such as aldehyde varnish-type epoxy resins; aralkyl-type epoxy resins, such as phenolic alkyl-type epoxy resins; dicyclopentadiene-type epoxy resins; biphenyl-type epoxy resins; naphthalene-type epoxy resins; anthracene-type epoxy resins; fluorene-skeletal-type epoxy resins; triphenol-type epoxy resins; etc. Among these, bisphenol A type epoxy resins and dicyclopentadiene type epoxy resins are preferred.

The number average molecular weight (Mn) of the epoxy resin (B1) is not particularly limited, but based on the viewpoints of the curability of the protective film forming layer and the strength and heat resistance of the protective film, it is preferably 300~30,000, more preferably 400~10,000, and even more preferably 500~3,000.

The epoxy equivalent of the epoxy resin (B1) is not particularly limited, but is preferably 100~1,000 g/eq, more preferably 120~800 g/eq, and even more preferably 150~500 g/eq. Furthermore, in this specification, "epoxy equivalent" refers to the number of grams (g/eq) of epoxy resin containing 1 gram equivalent of epoxy groups, which can be determined according to JIS K 7236:2001.

-Thermosetting agent (B2)- Thermosetting agent (B2) is a component that functions as a curing agent for epoxy resin (B1). Thermosetting agent (B2) can be used alone or in combination with two or more types.

Examples of thermosetting agents (B2) include compounds having two or more functional groups that can react 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 anhydrous acid groups. Among these, phenolic hydroxyl groups are preferred. Hereinafter, thermosetting agents (B2) having phenolic hydroxyl groups will be referred to as "phenolic curing agents".

Examples of phenolic curing agents include polyfunctional phenols, biphenols, phenolic varnish-type phenols, dicyclopentadiene-type phenols, and aralkyl-type phenols. Among these, phenolic varnish-type phenols are preferred, and O-cresol phenolic varnishes are even more preferred. Examples of amine-based curing agents containing amino groups include dicyandiamide.

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 it 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, compared to 100 parts by mass of epoxy resin (B1). When the content of the thermosetting agent (B2) is above the above-mentioned lower limit, the curing of the protective film forming layer tends to be easier. Furthermore, when the content of the thermosetting agent (B2) is below the above-mentioned upper limit, the moisture absorption rate tends to decrease, further improving the reliability of the semiconductor device containing the protective film forming layer (protective film).

In the protective film forming layer resin composition of this embodiment, the content of the thermosetting component (B) is not particularly limited, but relative to 100 parts by mass of the polymer component (A), it 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, even more preferably 500 to 1,000 parts by mass, and particularly preferably 650 to 800 parts by mass. When the content of the thermosetting component (B) is below the above-mentioned upper limit, there is a tendency to form a protective film with better protective performance.

(Curing Accelerator (C)) In this embodiment, the resin composition for the protective film forming layer may further include a curing accelerator (C). The curing accelerator (C) is a component used to adjust the curing rate of the protective film forming layer. The curing accelerator (C) may be used alone or in combination with two or more.

Examples of hardening accelerators (C) include, for example, tertiary amines such as triethyldiamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms); organophosphines such as tributylphosphine, diphenylphosphine, and triphenylphosphine (phosphines in which one or more hydrogen atoms are substituted with organic groups); tetraphenylborates such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate; etc. Of these, imidazoles are preferred, and 2-phenyl-4,5-dihydroxymethylimidazolium is more preferred, based on the view that it is easier to achieve the effects of the invention.

When the protective film forming layer resin composition contains a curing accelerator (C), the content of the curing accelerator (C) in the protective film forming layer resin composition is not particularly limited, but relative to the content of the thermosetting component (B) of 100 parts by weight, it is preferably 0.01 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and even more preferably 1 to 3 parts by weight. When the content of the curing accelerator (C) is above the above-mentioned lower limit, there is a tendency for the effect of using the curing accelerator (C) to be more significant. Furthermore, when the content of the curing accelerator (C) is below the aforementioned upper limit, for example, the effect of inhibiting the highly polar curing accelerator (C) from migrating to the bonding interface with the substrate under high temperature and high humidity conditions becomes higher, and the reliability of semiconductor devices using protective film forming resin compositions is further improved.

(Filler (D)) The protective film forming layer resin composition of this embodiment may further include filler (D). By including filler (D) in the protective film forming layer resin composition of this embodiment, the coefficient of thermal expansion of the protective film can be easily adjusted to an appropriate range, and the reliability of the encapsulation obtained using the protective film forming layer resin composition of this embodiment is further improved. Furthermore, by including filler (D) in the protective film forming layer resin composition of this embodiment, the moisture absorption rate of the protective film can be reduced, and heat dissipation can be improved. One type of filler (D) may be used alone, or two or more types may be used in combination.

The filler (D) can be either an organic or inorganic filler, but is preferably an inorganic filler. Examples of inorganic fillers include powders of silicon oxide, alumina, talc, calcium carbonate, iron oxide, silicon carbide, boron nitride, etc.; spheroidized beads of such inorganic fillers; surface-modified products of such inorganic fillers; single-crystal fibers of such inorganic fillers; glass fibers; etc. Among these, silicon oxide and alumina are preferred from the viewpoint that it is easier to achieve the effects of the present invention.

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 size is obtained by measuring the outer diameter of a single particle at several locations and calculating its average value.

When the resin composition for forming the protective film contains filler (D), the content of filler (D) in the resin composition for forming the protective film is not particularly limited. However, based on the viewpoint of suppressing the peeling of the protective film from the wafer due to thermal expansion and contraction, the content of the total amount of components other than inorganic fillers in the solid part of the resin composition for forming the protective film 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, relative to 100 parts by mass of the total amount of components other than inorganic fillers in the solid part of the resin composition for forming the protective film.

(Other Components (E)) The protective film forming layer of this embodiment may also contain other components (E) besides those mentioned above, to the extent that the effect of the invention is not impaired. Other components (E) may be known and can be selected arbitrarily according to the application, without particular limitation. Examples of other components (E) include crosslinking agents such as polymer component (A), surface conditioners such as silicone oil, coupling agents, surfactants, plasticizers, antioxidants, getters, etc. One or more other components (E) may be used alone. The content of other components (E) is not particularly limited, as long as they are appropriately selected according to the application.

(Soluble) The protective film forming layer of this embodiment is composed of a resin. From the viewpoint of improving treatability, it may further contain a solvent. A single solvent may be used alone, or two or more may be used in combination. Examples of solvents include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutanol (2-methylprop-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; amides (compounds containing amide bonds) such as dimethylformamide and N-methylpyrrolidone; etc. Among these, methyl ethyl ketone is preferred from the viewpoint of facilitating uniform mixing of the components.

(Preparation Method of Resin Composition for Protective Film Forming Layer) The protective film forming layer resin composition of this embodiment can be manufactured by formulating the above-mentioned components. The order of addition of the components is not particularly limited, and two or more components can be added simultaneously. The method of mixing the components is not particularly limited, as long as known methods such as rotating and mixing with a stir bar or stirring blades; mixing using a mixer; or mixing with ultrasonic waves are appropriately selected. The temperature and time during the addition and mixing of the components can be appropriately adjusted according to the types of components used, but the temperature is preferably 15~30°C.

(Preparation of protective film forming layer) The protective film forming layer of this embodiment can be manufactured by, for example, applying the protective film forming layer of this embodiment to the surface of the object to which it is formed with a resin composition and drying it as needed. The coating of the protective film forming layer with resin composition can be carried out using known methods, such as various coating machines including air knife coating machines, doctor blade coating machines, rod coating machines, gravure coating machines, roller coating machines, roller knife coating machines, curtain coating machines, stencil coating machines, knife coating machines, screen coating machines, Mayer rod coating machines, and contact coating machines. The drying conditions after applying the protective film to the resin composition are not particularly limited, but can be, for example, a drying temperature of 70~130°C and a drying time of 10 seconds to 5 minutes.

<Manufacturing Method of Composite Sheet for Protective Film Formation> The composite sheet for protective film formation of this embodiment can be manufactured by sequentially laminating layers in a manner that corresponds to the aforementioned layers. For example, a composite sheet for protective film formation having a substrate, a buffer layer, and a protective film forming layer in sequence can be manufactured by the method shown below. A composition for forming a buffer layer is coated on one side of a substrate, and dried as needed to obtain a first laminated sheet composed of a substrate and a buffer layer. A peelable film can be provided as needed on the side of the buffer layer opposite to the substrate in the first laminated sheet. In addition, by applying the protective film forming layer of this embodiment to the peeling treatment surface of the peeling film with a resin composition and drying it as needed, a protective film forming layer is formed on the peeling film.

Next, the exposed surface of the buffer layer in the first laminated sheet, opposite to the substrate, is bonded to the exposed surface of the protective film forming layer, opposite to the release film. This yields a composite sheet for forming a protective film, consisting of a substrate, a buffer layer, a protective film forming layer, and a release film sequentially laminated. The release film disposed on the protective film forming layer of the composite sheet for forming a protective film can be removed at any stage from the manufacturing of the composite sheet for forming a protective film to its use.

The composite sheet for forming a protective film having layers other than those mentioned above can be manufactured by appropriately adding or omitting steps in the above manufacturing method in such a way that the stacking positions of each layer are the desired positions.

<Physical properties of the composite sheet for forming protective film> The composite sheet for forming protective film of this embodiment preferably meets the following physical properties.

(Surface resistivity) The surface resistivity of the composite sheet for forming the protective film of this embodiment, measured by the method described in the following embodiments, is preferably 3.5 × ^10¹⁴ Ω/□ or less, more preferably 1.0 × ^10¹⁴ Ω/□ or less, even more preferably 5.0 × ^10¹³ Ω/□ or less, and particularly preferably 1.0 × ^10¹³ Ω/□ or less. The lower the surface resistivity, the better the composite sheet for forming the protective film exhibits electrostatic suppression.

(Penetration) The penetration amount of the composite sheet for forming a protective film in this embodiment, as measured by the method described in the following embodiments, is preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. The lower the penetration amount, the better the composite sheet for forming a protective film can be considered to have excellent long-term stability.

[Manufacturing Method of Semiconductor Device] Hereinafter, the manufacturing method of the semiconductor device of this embodiment will be described with reference to the drawings.

The method for manufacturing a semiconductor device according to this embodiment includes a step of forming a protective film on the bump formation surface of a semiconductor wafer using a composite sheet for forming a protective film. The preferred method for manufacturing a semiconductor device according to this embodiment includes steps 1 to 5 below. Step 1: Attaching the protective film forming layer of the protective film forming composite sheet of this embodiment to the bump forming surface of the semiconductor wafer, so that the top of the bump protrudes from the protective film forming layer, and the step of depositing the protective film forming composite sheet on the semiconductor wafer (hereinafter also referred to as the "attachment step"). Step 2: Removing the layers other than the protective film forming layer in the protective film forming composite sheet deposited in Step 1 (hereinafter also referred to as the "removal step"). Step 3: By applying the protective film forming composite sheet to the semiconductor wafer... Step 4: After step 3, the step of forming a protective film by hardening the protective film layer (hereinafter also referred to as the "hardening step") and the step of cutting the protective film after step 3 (hereinafter also referred to as the "cutting step") Step 5: The step of flip-chip bonding the semiconductor chip with the protective film attached to the substrate and mounting it (hereinafter also referred to as the "mounting step"). The following will explain each step with reference to the diagram.

<Step 1: Attachment Step> Figure 3 is a schematic cross-sectional view illustrating the attachment step. Figures 3(a) and (b) show the step of attaching the protective film forming composite sheet 1 to the bump forming surface 20a of the semiconductor wafer 20. In the attachment step, for example, as shown in Figure 3(a), the protective film forming layer 12 is positioned so that it faces the bump forming surface 20a of the semiconductor wafer 20. Next, the protective film forming layer 12 is brought into contact with the bumps 21 on the semiconductor wafer 20, and the protective film forming composite sheet 1 is pressed onto the semiconductor wafer 20. By pressing, the protective film forming layer 12 is sequentially pressed onto the surface of the bump 21 and the bump forming surface 20a of the semiconductor wafer 20. When the protective film forming composite sheet 1 is pressed onto the semiconductor wafer 20, the protective film forming layer 12 is pressed in by the dielectric buffer layer 11, and pressure is applied from the bump 21, causing the protective film forming layer 12 to crack. Finally, as shown in FIG. 3(b), the upper part of the bump 21 penetrates the protective film forming layer 12 and protrudes. When the protective film forming layer 12 of the protective film forming composite sheet 1 contains an antistatic agent, the penetration of the bump 21 is improved. Therefore, the workability of making the protective film layer 12 on the upper part of the protrusion 21 penetrate and protrude (workability of step 1) is improved.

The height of the bump 21 is not particularly limited, but it is preferably 120~300μm, more preferably 150~270μm, and even more preferably 180~240μm. In this specification, the term "bump height" refers to the height of the bump portion located at the highest point of the bump forming surface.

The width of bump 21 is not particularly limited, but is preferably 170~350μm, more preferably 200~320μm, and even more preferably 230~290μm. The term "bump width" in this specification refers to the maximum length of the line segment formed by connecting two different points on the surface of the bump with a straight line when looking down at the bump from a direction perpendicular to the bump forming surface.

The distance between adjacent protrusions 21 is not particularly limited, but is preferably 250~800μm, more preferably 300~600μm, and even more preferably 350~500μm. In this specification, the term "distance between adjacent protrusions" refers to the minimum distance between the surfaces of adjacent protrusions.

As a method for pressing the protective film forming composite sheet 1 onto the semiconductor wafer 20, known methods for pressing and attaching various sheets to an object can be applied, such as methods using a roller laminator. The heating temperature for pressing the protective film forming composite sheet 1 onto the semiconductor wafer 20 is not particularly limited, but can be, for example, 80~100°C, preferably 85~95°C. The pressure for pressing the protective film forming composite sheet 1 onto the semiconductor wafer 20 is not particularly limited, but can be, for example, 0.1~1.5 MPa, preferably 0.3~1 MPa. The speed for attaching the protective film forming composite sheet 1 onto the semiconductor wafer 20 is not particularly limited, but is typically around 2 mm/s. Here, when the buffer layer 10 of the protective film forming composite sheet 1 contains an antistatic agent, it can be made to have excellent high-speed adhesion. Therefore, the speed of attaching the protective film forming composite sheet 1 to the semiconductor wafer 20 can be improved. Specifically, it is preferable to increase it to 5 mm/s or more, and even more preferably to 5 mm/s to 10 mm/s, and the workability of attaching the protective film forming composite sheet 1 to the semiconductor wafer 20 (workability of step 1) can be improved.

After the attachment step, if necessary, the side (back side) of the semiconductor wafer 20 opposite to the bump formation surface 20a can be ground, and then another protective film forming composite sheet (illustration omitted) can be attached to the ground back side.

<Step 2: Removal Step> Figure 4 is a schematic cross-sectional view illustrating the removal step. After the attachment step, as shown in Figure 4, the layers other than the protective film forming layer 12 in the composite sheet 1 for forming the protective film are removed to obtain a semiconductor wafer 30 having a semiconductor wafer 20 and a protective film forming layer 12 disposed 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 known methods.

<Step 3: Hardening Step> Figure 5 is a schematic cross-sectional view illustrating the hardening step. After removing the step, as shown in Figure 5, the protective film layer 12 is thermally hardened, and a protective film 12' formed by thermally hardening the protective film layer 12 is formed on the bump formation surface 20a of the semiconductor wafer 20. This yields a semiconductor wafer 40 with a protective film 12' on the bump formation surface 20a of the semiconductor wafer 20. The conditions for hardening the protective film layer are not particularly limited and can be appropriately adjusted and determined according to the type of material constituting the protective film layer.

<Step 4: Segmentation and Cutting Steps> Figure 6 is a schematic cross-sectional view illustrating the segmentation and cutting steps. After the hardening step, as shown in Figure 6, in the segmentation step, a semiconductor chip 50 is fabricated by segmenting the semiconductor wafer 20. Furthermore, in the 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 attached, having the cut protective film 120' on the bump formation surface of the semiconductor chip 50.

The dicing and cutting steps can be performed using known methods. The order in which the dicing and cutting steps are performed is not particularly limited, but it is preferable that they are performed simultaneously or sequentially. When the dicing and cutting steps are performed sequentially, for example, the dicing step can be performed using known cutting methods, followed immediately by the cutting step. Cutting can be performed by providing a dicing sliver (not shown) on the back side of the semiconductor wafer 20 (which may be the ground back side). In the cutting step, the protective film 12' is cut along the predetermined dicing portion of the semiconductor wafer 20 or through the dicing portion (in other words, the outer periphery of the semiconductor chip 40).

<Step 5: Installation Step> In the installation step, the semiconductor chip 60 with protective film obtained in the curing step is flip-chip bonded to the substrate at the top of the bump 21 (illustration omitted). At this time, the semiconductor chip 60 with protective film is connected to the circuit formation surface of the substrate.

Subsequently, using the circuit substrate with the semiconductor chip mounted as obtained in this way, a semiconductor package is fabricated according to known methods, and a desired semiconductor device can be manufactured using the semiconductor package. [Example]

The present invention is illustrated in more detail by way of the following embodiments, but the present invention is not limited to the following embodiments.

[Method for Determination of Mass Average Molecular Weight (Mw)] The method for determining the mass average molecular weight (Mw) in this embodiment is described below. A gel osmosis chromatography system (manufactured by Tosoh Corporation, product name "HLC-8320GPC") was used, and the determination was performed under the following conditions, using values converted from standard polystyrene. (Determination Conditions) • Column: A series of "TSKgel Protective Column SuperHzH", "TSKgel SuperHZM-M", "TSKgel SuperHZM-M", and "TSKgel SuperHZ2000" (all manufactured by Tosoh Corporation) connected sequentially. • Column Temperature: 40°C • Spreading Solvent: Tetrahydrofuran • Standard Substance: Polystyrene • Injection Volume: 20 μL • Flow Rate: 0.35 mL/min • Detector: Differential Refractometer

[Examples 1-12, Comparative Example 1] Protective film forming composite sheets of Examples 1-12 and Comparative Example 1 were manufactured, with differences in the layers containing antistatic agents, the type of antistatic agent, and the amount of antistatic agent added. The evaluation is described below. The protective film forming composite sheet of Comparative Example 1 is a protective film forming composite sheet in which no layer contains antistatic agents. The protective film forming composite sheets of Examples 1-8 are protective film forming composite sheets in which only the buffer layer contains antistatic agents. The protective film forming composite sheets of Examples 9-11 are protective film forming composite sheets in which only the protective film forming layer contains antistatic agents. The protective film forming composite sheet of Embodiment 12 is a protective film forming composite sheet in which both the buffer layer and the protective film forming layer contain antistatic agents. Details of the layers containing antistatic agents, the types of antistatic agents, and the amounts of antistatic agents added are shown in Table 2.

<Types of Antistatic Agents> Details of antistatic agents B to D used in this embodiment are shown in Table 1. Also, as shown in Table 1, all antistatic agents are liquids at room temperature (23°C).

[Table 1] Antistatic agent Manufacturer Product Name Element Characteristics B Japanese emulsifier manufacturer Amino ions RE3000MF Amino salts liquid C Dacheng Precision Chemical Manufacturing Acrylit 8SX-1096JC Cationic acrylic resin liquid D Made in Japan Carlit CIL-R50 Imidazolium salt liquid

In this embodiment, in order to produce a composite sheet for forming a protective film having the layer structure shown in Table 2, specific amounts of specific antistatic agents B to D are incorporated into the resin composition for the buffer layer prepared in "Preparation of Substrate with Buffer Layer" and the resin composition for the protective film forming layer prepared in "Preparation of Protective Film Forming Layer". Furthermore, the amount of antistatic agent added (unit: parts by mass) shown in Table 2 refers to the amount of antistatic agent added when the amount of solids in the resin composition for the buffer layer or the resin composition for the protective film forming layer after removing the antistatic agent is set to 100 parts by mass. Furthermore, the amount of antistatic agent added shown in Table 2 (unit: mass %) refers to the amount of antistatic agent added based on the total solid content (100 mass %) of the resin composition of the buffer layer or the resin composition of the protective film forming layer.

<Preparation of the Substrate with Cushioning Layer> The following are prepared: 40 parts by weight of monofunctional aminocarbamate acrylate, 45 parts by weight of isobornyl acrylate (IBXA), 15 parts by weight of 2-hydroxypropyl acrylate (HPA), 3.5 parts by weight of pentaerythritol tetra(3-methylbutyrate) (Showa Denko Co., Ltd., product name "Karenz MT (registered trademark) PE1", a secondary tetrafunctional thiol compound, solids concentration 100% by weight), 1.8 parts by weight of crosslinking agent, and 2-hydroxy-2-methyl-1-phenylpropane-1-one (BASF Corporation, product name "Dalocure (registered trademark) 1173", solids concentration 100% by weight) as a photopolymerization initiator. 1.0 parts by weight were used to prepare a cushioning layer resin composition. This cushioning layer resin composition was applied onto a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine A4300", thickness 75 μm) to form a coating. Then, ultraviolet light was irradiated from the coating side to form a semi-cured layer. Furthermore, the ultraviolet irradiation was conducted using a belt conveyor type ultraviolet irradiation device (manufactured by EYE Graphic Co., Ltd., product name "ECS-401GGX") as the ultraviolet irradiation device, and a high-pressure mercury lamp (manufactured by EYE Graphic Co., Ltd., product name "H04-L41") as the ultraviolet source. The irradiation conditions were 120 mW/ ^cm2 at a wavelength of 365 nm and 200 mJ/ ^cm2 (measured by EYE Graphic Co., Ltd., product name "UVPF-A1"). A PET-based release film (manufactured by Lintec Corporation, product name "SP-PET381031"), which is made by laminating a polyethylene terephthalate (PET) film on one side and then undergoing silicone treatment and release treatment, is subjected to ultraviolet irradiation from the PET-based release film side (using the aforementioned ultraviolet irradiation device and ultraviolet source as irradiation conditions of 330mW/ ^cm2 and 1,200mJ/ ^cm2 ) to achieve complete curing, thereby forming a 400μm thick buffer layer on the PET-based film as the substrate, thus obtaining a substrate with a buffer layer.

<Preparation of Protective Film Forming Layer> (Raw Materials) (1) Polymer Component (A) Polyvinyl butyral (manufactured by Sekisui Chemicals Co., Ltd., product name "S-LEC BL-10", mass average molecular weight (Mw) 25,000, glass transition temperature 59°C) having the constituent units represented by Formula (i)-1, Formula (i)-2 and Formula (i)-3 below.

(In the formula, _l1 is approximately 28, _m1 is 1~3, and _n1 is an integer from 68 to 74).

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

(3) Thermosetting agent (B2)・(B2)-1: O-cresol type phenolic varnish resin (manufactured by DIC Corporation, product name "Phenolite KA-1160")

(4) Hardening accelerator (C)・(C)-1:2-phenyl-4,5-dihydroxymethylimidazol (manufactured by Shikoku Chemical Industry Co., Ltd., product name "CUREZOL 2PHZ-PW")

(5) Filler (D)・(D)-1: Spherical silicon oxide modified with epoxy groups (manufactured by ADMATECHS Co., Ltd., product name "ADMANANO YA050C-MKK", average particle size 50nm)

(6) Additives (E)・(E)-1: Surfactant (acrylic polymer, manufactured by BYK Corporation, product name "BYK-361N")・(E)-2: Silicon oil (arane-modified silicone oil, manufactured by Momentive Performance Materials, Japan, product name "XF42-334")

(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), thermosetting 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) are dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to obtain a resin composition for protective film forming layer with a total concentration of 45% by mass for all components except the solvent. Furthermore, all the amounts of ingredients other than solvent shown here are solvent-free amounts.

(Preparation of protective film forming layer) The protective film forming layer obtained above is coated with a resin composition on the peeling surface of a PET-based release film (Lintec "SP-PET381031", thickness 38μm), and dried at 120°C for 2 minutes to form a protective film forming layer with a thickness of 30μm on the PET-based release film.

<Preparation of the Intermediate Release Layer> At room temperature, ethylene-vinyl acetate copolymer (EVA, mass average molecular weight 55,000, derived from 20% by mass of vinyl acetate constituent units) was dissolved in toluene to prepare an intermediate release layer resin composition with a solids concentration of 12% by mass. Then, the intermediate release layer resin composition was coated on the release-treated surface of a PET-based release film (Lintec "SP-PET381031", thickness 38μm) and dried at 100°C for 2 minutes to form an intermediate release layer with a thickness of 10μm on the PET-based release film.

<Preparation of Composite Sheet for Protective Film Formation> A PET-based release film with a buffer layer attached is peeled off from the substrate, and an intermediate release layer is laminated onto the exposed surface. Next, a PET-based release film with the intermediate release layer is peeled off, and a protective film forming layer is laminated onto the exposed surface to produce a composite sheet for protective film formation. The laminated structure of the composite sheet for protective film formation is as follows: • Substrate/Buffer Layer/Intermediate Release Layer/Protective Film Forming Layer/PET-based Release Film The composite sheet for protective film formation with this structure is used in Comparative Examples 1, Examples 1-5, Examples 7-10, and Example 12.

Furthermore, a PET-based release liner is peeled off from the substrate with the buffer layer, and a protective film forming layer is laminated onto the exposed surface to produce a composite sheet for forming a protective film. The laminated structure of the composite sheet for forming a protective film is as follows: • Substrate/Buffer Layer/Protective Film Forming Layer/PET-based Release Liner In Embodiments 6 and 11, the composite sheet for forming a protective film with this structure is used.

[Evaluation] In this embodiment, the following evaluations 1 to 4 are performed.

<Evaluation 1: Evaluation of Electrostatic Discharge (ESD)> Using the composite sheet for forming the protective film of Examples 1-12 and Comparative Example 1, a 10cm × 10cm square sample was prepared. The surface resistivity of the square sample was measured using a digital electrostatic meter (manufactured by ADVANTEST, product name "R8252-TR42"). The applied voltage during measurement was set to 100V. It can be said that the smaller the surface resistivity, the better the electrostatic discharge suppression. The evaluation criteria are as follows. In this example, evaluation 0 and evaluation △ are qualified. • Evaluation 0: Surface resistivity less than 1.0 × 10 ¹⁴ Ω/□. • Evaluation △: Surface resistivity is 1.0 × 10 ¹⁴ Ω/□ or more, and 3.5 × 10 ¹⁴ Ω/□ or less. • Evaluation ×: Surface resistivity greater than 3.5 × 10 ¹⁴ Ω/□.

<Evaluation 2: Evaluation of High-Speed Adhesion> After peeling off the PET-based release film from the protective film forming layer of the protective film forming composite sheet of Examples 1-12 and Comparative Example 1, an adhesion device was used to adhere the protective film forming composite sheet to the bump forming surface of a bump-bearing semiconductor wafer. The adhesion surface of the protective film forming composite sheet to the bump forming surface of the bump-bearing semiconductor wafer is the protective film forming layer side. The specifications of the bump-bearing semiconductor wafer are as follows. (Specifications)・Wafer size: 8 inches・Wafer thickness: 645μm・Bump height: 210μm・Bump width: 250μm・Bump spacing: 400μm The mounting device uses a roller laminator (Lintec RAD-3520 F/12) and is mounted under the following mounting conditions. The mounting speed is typically set to around 2mm/s; the mounting speed in this embodiment is more than twice the normal speed. (Modification conditions)・Stage temperature: 80℃・Modification speed: 5mm/s・Modification pressure: 0.1MPa・Roller mounting height: 0μm

After attaching a protective film forming composite sheet to the bump forming surface of a semiconductor wafer with bumps, a layer other than the protective film forming layer of the protective film forming composite sheet is peeled off. Next, after thermosetting the protective film forming layer, the irregularities of the bump forming surface extend beyond the protective film, and are observed using a digital microscope (KEYENCE, VHX-7000) at 100x magnification. The thermosetting conditions for the protective film forming layer are 130°C for 4 hours. The observation area is set as the central 2cm × 2cm area of the semiconductor wafer. The evaluation criteria are as follows. In this embodiment, evaluation 0 and evaluation △ are considered acceptable. • Evaluation 0: No bubbles are formed between the bump forming surface and the protective film; the irregularities caused by the bumps are embedded. • Evaluation △: Although slight air bubbles are generated between the bump forming surface and the protective film, the bumps and dents caused by the bumps can be embedded without any problems. • Evaluation ×: The bumps and dents caused by the bumps cannot be embedded, and the protective film will bulge from the bump forming surface.

<Evaluation 3: Evaluation of Residue on the Top> For a portion of the samples after Evaluation 2, a field emission scanning electron microscope (FE-SEM, Hitachi High-Tech S-4700) was used to observe the top of the bumps, confirming the exposure status of the bumps and the residue originating from the protective film agglomerate. The evaluation criteria are as follows. In this embodiment, Evaluation 0 is considered acceptable. • Evaluation 0: At least part of the bump on the top of the bump is exposed. • Evaluation ×: The bump on the top of the bump is not exposed, and the protective film agglomerate remains on the bump (the protective film agglomerate covers the bump, and the bump is not exposed at all).

<Evaluation 4: Permeability Evaluation> The composite sheets for protective film formation from Examples 1-12 and Comparative Example 1 were cut into 3cm squares. One side was subjected to a 2kg load while the other side was placed at 40°C for 7 days. Subsequently, after returning to room temperature (23°C) and removing the load, permeation was visually confirmed. For those with permeation, the amount of permeation was measured with a ruler. The smaller the amount of permeation, the better the composite sheet for protective film formation can be considered to have excellent long-term stability.

The evaluation results are shown in Table 2.

As shown in Table 2, the results of Examples 1-12 demonstrate that by including an antistatic agent in either the buffer layer or the protective film forming layer, a composite sheet for forming a protective film with excellent static electricity suppression and improved workability in the manufacturing process of semiconductor devices can be produced. Specifically, as shown in Examples 1-8 and Example 12, by including an antistatic agent in the buffer layer, a composite sheet for forming a protective film with excellent static electricity suppression and high-speed adhesion can be produced. Furthermore, as shown in Examples 9-11 and Example 12, by including an antistatic agent in the protective film forming layer, a composite sheet for forming a protective film with excellent static electricity suppression and reduced head residue (in other words, excellent bump penetration) can be produced.

1,2: Composite sheet for protective film formation; 10: Substrate; 10a: One side of the substrate; 11: Buffer layer; 12: Protective film forming layer; 13: Peel-off film; 20: Semiconductor wafer; 20a: Bump forming surface of the semiconductor wafer; 21: Bump; 30: Semiconductor wafer with protective film forming layer; 40: Semiconductor wafer with protective film; 50: Semiconductor chip; 60: Semiconductor chip with protective film.

[Figure 1] is a schematic cross-sectional view showing an example of the composite sheet for forming a protective film according to this embodiment. [Figure 2] is a schematic cross-sectional view showing another example of the composite sheet for forming a protective film according to this embodiment. [Figure 3] is a schematic cross-sectional view showing a portion of the manufacturing method of a semiconductor device according to this embodiment. [Figure 4] is a schematic cross-sectional view showing a portion of the manufacturing method of a semiconductor device according to this embodiment. [Figure 5] is a schematic cross-sectional view showing a portion of the manufacturing method of a semiconductor device according to this embodiment. [Figure 6] is a schematic cross-sectional view showing a portion of the manufacturing method of a semiconductor device according to this embodiment.

1: Composite film for forming protective film

10: Substrate

10a: One side of the substrate

11: Buffer Layer

12: Protective film forming layer

Claims (6)

A composite sheet for forming a protective film is characterized by having a substrate, a buffer layer, and a protective film forming layer in sequence, wherein at least one of the buffer layer and the protective film forming layer contains an antistatic agent. The composite sheet for forming a protective film as described in claim 1, wherein the layers of the aforementioned buffer layer and the aforementioned protective film forming layer contain the aforementioned antistatic agent. The composite sheet for forming a protective film as described in claim 1 or 2, wherein an intermediate release layer is further provided between the aforementioned buffer layer and the aforementioned protective film forming layer. The composite sheet for forming a protective film as described in claim 3, wherein the aforementioned intermediate release layer contains an ethylene-vinyl acetate copolymer. As described in claim 1 or 2, the protective film forming layer is a thermosetting protective film forming layer. A method for manufacturing a semiconductor device, characterized by comprising the step of forming a protective film on the bump forming surface of a semiconductor wafer using a composite sheet for forming a protective film as described in claim 1 or 2.