TWI899109B - Film for forming protective film, composite sheet for forming protective film, and method for producing segment containing protective film - Google Patents

Abstract

An object of the present invention is to suppress the occurrence of chipping when a workpiece such as a semiconductor wafer and a protective film are cut using a dicing blade to produce fragments containing a protective film. A protective film-forming film 1 according to the present invention includes a filler 2. In cross-sectional observation of the film 1, when the total thickness of the film is T, a first region is defined as the area from the surface of one side of the film to a depth of 0.2T, and a second region is defined as the area from the surface of the other side of the film to a depth of 0.2T. The 50% cumulative diameter D ₅₀ 1 of the filler observed in the first region and the 50% cumulative diameter D ₅₀ 2 of the filler observed in the second region satisfy the following conditions: D ₅₀ 1 < D ₅₀ 2, and (D ₅₀ 2 - D ₅₀ 1)/D ₅₀ 1 × 100 ≧ 5 (%).

Description

Film for forming protective film, composite sheet for forming protective film, and method for producing segment containing protective film

The present invention relates to a film for forming a protective film capable of forming a protective film on a workpiece such as a semiconductor wafer or a processed product obtained by processing the workpiece (e.g., a semiconductor chip), a composite sheet for forming a protective film, and a method for manufacturing a fragment containing a protective film such as a semiconductor chip containing a protective film using the obtained composite sheet.

In recent years, semiconductor device manufacturing has been performed using a flip-chip assembly method. This method involves assembling a semiconductor chip with a circuit surface on which electrodes, such as bumps, are formed. The circuit surface side of the semiconductor chip is bonded to a chip mounting portion, such as a lead frame. This results in a structure where the inner surface of the semiconductor chip, where no circuits are formed, is exposed.

Therefore, a protective film made of a hard organic material is often formed on the inner surface of a semiconductor wafer to protect the semiconductor wafer. This protective film is formed using a dicing sheet containing a protective film forming film, such as that described in Patent Document 1 or Patent Document 2.

When forming a protective film on a semiconductor wafer, etc., using a dicing sheet containing a protective film-forming film, the protective film-forming film on the dicing sheet is adhered to the inner surface of the semiconductor wafer. The semiconductor wafer and the protective film-forming film are then cut using a wafer dicing blade, etc., to obtain a laminate of the semiconductor wafer and the protective film-forming film of the same shape. Fillers are blended into the protective film to control the strength of the protective film, control shrinkage during curing, and impart laser marking properties. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Publication No. 2011-9711 Patent Document 2: Japanese Patent Application Publication No. 2011-151360

[Problem to be solved]

Semiconductor chips, obtained by dicing semiconductor wafers, sometimes develop cracks during dicing. This is also called chipping, and it can reduce the flexural strength of the semiconductor chip and cause failure. While chipping can take many forms, it can sometimes develop as a linear crack running from the inner side to the outer surface of the semiconductor chip.

The inventors studied the cause of these stripe-like cracks and speculated that the cause is the shaking of the wafer dicing blade caused by the impact during dicing. When a semiconductor wafer and a protective film are cut by a wafer dicing blade, the blade enters from the surface of the semiconductor wafer. After the wafer is cut, the blade cuts the protective film. Because the protective film contains fillers and resins, the load applied to the blade when cutting the hard filler is different from when cutting the soft resin, causing the blade to shake and vibrate. As a result, it is speculated that the blade strikes the cut surface of the wafer, causing cracks.

Blade shaking is particularly prone to occur when cutting large fillers. Therefore, it is speculated that reducing the particle size of the filler blended into the protective film-forming film can suppress blade shaking and vibration. However, as the particle size of the filler blended into the protective film-forming film decreases, the support provided by the protective film-forming film decreases, causing blade vibration to become more likely, and failing to fully reduce chipping. Furthermore, when the particle size of the filler blended into the protective film-forming film decreases, even when laser marking is performed on the protective film-forming film or its cured product, sufficient contrast cannot be achieved, resulting in reduced visibility of the marking. Therefore, an object of the present invention is to suppress the occurrence of chipping when a workpiece such as a semiconductor wafer and a protective film are cut using a wafer dicing blade, and when fragments containing a protective film, such as semiconductor chips containing a protective film, are produced. [Solution]

To achieve the above objectives, after intensive research, we discovered that by blending a relatively small particle size filler into the upper region of the protective film-forming film (the area in contact with the workpiece) where the blade first contacts the protective film, and blending a relatively large particle size filler into the lower region of the protective film-forming film (the area interposed with the dicing blade), we can suppress blade shake and vibration during cutting. Furthermore, it is speculated that blending a relatively large particle size filler into the lower region of the protective film-forming film (the surface where the protective film is exposed) also allows for sufficient laser marking performance. Thus, the present invention, which achieves these objectives, includes the following key features.

(1) A protective film-forming film comprising a filler, wherein, in cross-sectional observation of the film, when the total thickness of the film is T, the first region is defined as the area from the surface of one side of the film to a depth of 0.2T, and the second region is defined as the area from the surface of the other side of the film to a depth of 0.2T. The 50% cumulative diameter D ₅₀ 1 of the filler observed in the first region and the 50% cumulative diameter D ₅₀ 2 of the filler observed in the second region satisfy the following conditions: D ₅₀ 1 < D ₅₀ 2, and (D ₅₀ 2 - D ₅₀ 1) / D ₅₀ 1 × 100 ≧ 5 (%). (2) The protective film-forming film as described in (1), comprising two or more constituent layers. (3) A film for forming a protective film as described in (1) or (2), wherein the filler is an inorganic filler. (4) A film for forming a protective film as described in (3), wherein the inorganic filler is a silicon oxide filler. (5) A film for forming a protective film as described in any one of (1) to (4), wherein the surface on the first region side is adhered to a workpiece. (6) A composite sheet for forming a protective film, comprising: an adhesive sheet formed by laminating a substrate and an adhesive layer, and a film for forming a protective film as described in any one of (1) to (5) laminated on the adhesive layer side of the adhesive sheet, wherein the surface on the second region side of the protective film is laminated on the adhesive layer. (7) A method for producing a fragment containing a protective film, comprising the following steps (1) to (4): Step (1): a step of attaching the surface of the first region side of the protective film forming film of the protective film forming composite sheet described in (6) above to a workpiece; Step (2): a step of heat-curing the protective film forming film to obtain a protective film; Step (3): a step of cutting the workpiece and the protective film forming film or the protective film to obtain single-piece fragments of the same shape and a laminate of the protective film forming film or the protective film; and Step (4): a step of separating the protective film forming film or the protective film from the adhesive sheet. [Effects of the Invention]

The protective film-forming film and protective film-forming composite sheet according to the present invention can suppress the shaking and vibration of the blade when cutting the workpiece and the laminated body of the protective film-forming film by a wafer dicing knife, thereby reducing the stripe-like cracks that sometimes occur from the inner side to the surface side of the semiconductor chip.

The present invention will be described in detail below. First, the main terms used in this specification will be described.

(Meth)acrylate is a term that refers to both "acrylate" and "methacrylate," and the same applies to other similar terms. An adhesive sheet refers to a laminate comprising a substrate and an adhesive layer, and may also include other constituent layers. For example, an adhesive sheet may have an intermediate layer between the substrate and the adhesive layer. Alternatively, a primer layer may be formed on the surface of the substrate on the adhesive layer side to improve adhesion between the substrate and adhesive layer interface, or between the substrate and intermediate layer interface, or to prevent the migration of low-molecular-weight components. Alternatively, a release film may be deposited on the surface of the adhesive layer to protect the adhesive layer until use. Furthermore, the substrate may be a single layer or a multilayer structure including functional layers such as a buffer layer.

The dicing sheet is an adhesive sheet used to hold the wafer and chips together when singulating the wafer into individual chips for each circuit.

A protective film-forming film is used to form a protective film on a workpiece or an object obtained by processing the workpiece. The protective film may be an uncured protective film-forming film, but is preferably composed of a cured protective film. Examples of workpieces include semiconductor wafers, and examples of objects obtained by processing the workpiece include fragments of semiconductor wafers, but the present invention is not limited thereto. Furthermore, when the workpiece is a semiconductor wafer, the protective film is formed on the inner surface of the semiconductor wafer (the side where electrodes such as bumps are not formed). The "surface" of a semiconductor wafer refers to the side where circuits, electrodes, etc. are formed, while the "inner surface" refers to the side where circuits, etc. are not formed.

[Protective Film Forming Film] As shown in FIG1 , a protective film forming film 1 includes a filler 2, and is characterized in that the filler particle size near one surface of the film is different from that near the other surface. Specifically, in cross-sectional observation of the protective film-forming film 1, when the total thickness of the film is T, the area from the surface of one side of the film (hereinafter sometimes referred to as the first surface) to a depth of 0.2T is defined as the first region, and the area from the surface of the other side of the film (hereinafter sometimes referred to as the second surface) to a depth of 0.2T is defined as the second region, the 50% cumulative diameter D ₅₀ 1 of the filler observed in the first region and the 50% cumulative diameter D ₅₀ 2 of the filler observed in the second region satisfy the following: D ₅₀ 1＜D ₅₀ 2, and (D ₅₀ 2-D ₅₀ 1)/D ₅₀ 1×100≧5(%). The 50% cumulative diameter refers to the particle size at which 50% of the particles observed within a specific range are accumulated, arranged starting from the smaller particle size side.

When the protective film forming film of the present invention is attached to a workpiece, the first surface is attached to the workpiece. When laser marking is performed on the protective film forming film or the protective film, it is performed on the second surface.

(D ₅₀ 2 - D ₅₀ 1) / D ₅₀ 1 × 100 (%) is preferably 10% or greater, more preferably 20% or greater, and particularly preferably 30% or greater. If (D ₅₀ 2 - D ₅₀ 1) / D ₅₀ 1 × 100 is less than 5%, the difference between the 50% cumulative diameter of the filler in the first region and the 50% cumulative diameter of the filler in the second region is small, and the effect of suppressing chipping cannot be fully achieved. The upper limit of (D ₅₀ 2 - D ₅₀ 1) / D ₅₀ 1 × 100 (%) is not particularly limited, but is preferably less than 10,000%, more preferably less than 5,000%, and even more preferably less than 3,000%.

Furthermore, D ₅₀ 2 / D ₅₀ 1 is preferably less than 100, more preferably less than 50, and particularly preferably less than 30. When there is a significant difference between the filler particle size in the first region and the filler particle size in the second region, for example, when (D ₅₀ 2 - D ₅₀ 1) / D ₅₀ 1 × 100 (%) is 10000% or greater, or when D ₅₀ 2 / D ₅₀ 1 is 100 or greater, the protective film-forming thin film may peel from the semiconductor chip during the reflow step. In particular, when the protective film-forming film is a two-layer product, where a first film with a small filler particle size is directly laminated with a second film with a larger filler particle size, if the difference in filler particle size is too large, the difference in thermal expansion coefficient between the first and second films increases, potentially causing delamination at the interface between the first and second films during the reflow step. Even when the protective film-forming film is a single-layer structure, if the difference in filler particle size is too large, the adhesion strength on the first surface becomes insufficient, potentially causing the protective film-forming film to delaminate from the semiconductor wafer.

_D501 is preferably in the range of 0.01 to 2μm, more preferably 0.05 to 1μm, and particularly preferably 0.05 to 0.5μm. If _D501 is too large, the blade tends to wobble and vibrate more when cutting the protective film. If _D501 is too small, the viscosity of the coating liquid used to form the first area increases, making coating difficult. Furthermore, _D502 is preferably in the range of 0.01 to 3μm, more preferably 0.05 to 2μm, and particularly preferably 0.1 to 1μm. If _D502 is too small, laser marking properties decrease, while if it is too large, the surface of the protective film becomes rough.

In other embodiments of the present invention, the maximum diameter Dmax1 of the filler observed in the first region and the maximum diameter Dmax2 of the filler observed in the second region preferably satisfy the following relationship.

Other embodiments of the present invention satisfy Dmax1<Dmax2, and (Dmax2-Dmax1)/Dmax1×100≧5(%).

(Dmax2-Dmax1)/Dmax1×100(%) is preferably 10% or greater, more preferably 20% or greater, and particularly preferably 30% or greater. If (Dmax2-Dmax1)/Dmax1×100 is less than 5%, the effect of suppressing chipping cannot be fully achieved. There is no particular upper limit for (Dmax2-Dmax1)/Dmax1×100(%), but it is preferably less than 10,000%, more preferably less than 5,000%, and even more preferably less than 3,000%.

Furthermore, Dmax2/Dmax1 is preferably less than 100, more preferably less than 50, and particularly preferably less than 30. If the difference between Dmax1 and Dmax2 is too large, the protective film may peel off from the semiconductor chip during the reflow step as described above.

Dmax1 is preferably in the range of 0.01-5μm, more preferably 0.05-3μm, and particularly preferably 0.1-2μm. If Dmax1 is too large, the blade tends to wobble and vibrate more during cutting of the protective film. If Dmax1 is too small, the viscosity of the coating liquid used to form the first area increases, making coating difficult. Furthermore, Dmax2 is preferably in the range of 0.05-8μm, more preferably 0.1-6μm, and particularly preferably 0.3-5μm. If Dmax2 is too small, laser marking performance decreases, while if Dmax2 is too large, the surface of the protective film becomes rough.

The filler particle size (Dmax, _D50 ) of a protective film-forming film is determined by curing the protective film, cutting the cured film, and observing the cross section. The maximum and cumulative filler diameters are determined. Cross-sectional observation can be performed on a field containing at least 10 fillers per region, or multiple fields can be observed, with the diameters of a total of 10 or more fillers measured. The filler diameter observed in cross section represents the filler cross-sectional diameter. Therefore, depending on the filler cut position, the filler may be observed as the long diameter, or the filler end may form the cut surface. Therefore, the filler diameter observed in cross section may differ from the filler diameter of the powder used as the raw material. The filler diameter observed in cross section is calculated as the equivalent diameter of a circle. "Circle equivalent diameter" refers to the diameter of a circle with the same area as the cross-section of the packing, also known as the projected area equivalent diameter (Heywood diameter).

Furthermore, the filler content (mass) in the protective film-forming film of this embodiment is preferably substantially the same. The filler content (M1) in the first region and the filler content (M2) in the second region are substantially equal, with the ratio M1/M2 preferably being in the range of 0.8 to 1.3, more preferably 0.9 to 1.2, and particularly preferably 0.95 to 1.1. If the difference between M1 and M2 is too large, a difference in shrinkage during curing of the protective film-forming film may occur, leading to peeling of the protective film and wafer lift.

The average filler content in the protective film-forming film is preferably 10 to 80% by mass, particularly 20 to 70% by mass, and even more preferably 30 to 65% by mass, relative to the total mass of the protective film-forming film. If the filler content is too low, the protective film may lack strength, while if it is too high, the protective film may lack adhesiveness.

The thickness of the protective film-forming film is preferably 3 to 300 μm, particularly 5 to 200 μm, and even more preferably 7 to 100 μm, in order to effectively function as a protective film. When the protective film-forming film is a multi-layer product, the total thickness is referred to.

The protective film-forming film according to this embodiment may be formed of a single layer or multiple layers. In the case of a single-layer film, while the filler diameters in the first region and the second region satisfy the above-described requirements, it is preferred that the filler diameter increase continuously or in stages from the first region to the second region. Therefore, a region in which the filler diameter increases continuously or in stages is preferably formed between the first and second regions.

When the protective film-forming film is formed from multiple layers, it can be a two-layer product consisting of a first film having a filler diameter that satisfies the first region, and a second film having a filler diameter that satisfies the second region. Furthermore, a third film containing a filler can be included between the first and second films. The third film can have a structure in which the filler diameter increases continuously from the surface in contact with the first film to the surface in contact with the second film. Furthermore, the third film can be a multi-layered structure in which the filler diameter increases stepwise from the surface in contact with the first film to the surface in contact with the second film. When a third film is provided, M1/M2, which is the ratio of the filler content (M1) in the first region to the filler content (M2) in the second region, can also be outside the preferred range described above. From the viewpoint of ease of production, it is preferred that the protective film-forming film be a multi-layer product.

When the protective film forming film has a plurality of constituent layers, the thickness of each constituent layer is not particularly limited, but is preferably about 1 to 30 μm, further preferably about 2 to 20 μm, and particularly preferably about 3 to 15 μm.

The protective film is preferably formed from an uncured resin composition. In this case, after the protective film is laminated onto a workpiece such as a semiconductor wafer, the protective film is cured to securely adhere to the workpiece, allowing a durable protective film to be formed on the wafer.

Furthermore, when the protective film-forming film is formed of an uncured resin composition containing a filler, the dispersion state of the filler in the protective film-forming film after curing is almost unchanged from the dispersion state before curing.

The protective film has adhesive properties at room temperature, but preferably develops its adhesive properties upon heating. This allows the two to be bonded together when a workpiece, such as a semiconductor wafer, is stacked on the protective film, as described above. This ensures that positioning can be performed reliably before the protective film hardens.

The resin composition constituting the protective film-forming film having the above-mentioned properties preferably contains a filler, a curable component, and a binder polymer component.

As fillers, either inorganic fillers or organic fillers can be used. Among these, inorganic fillers are preferred, and silica such as crystalline silica, molten silica, and synthetic silica; inorganic fillers such as aluminum oxide and glass balls can be used. Among these, silica is preferred, and synthetic silica is more preferred. In particular, synthetic silica of a type that effectively eliminates the radiation source of α rays, which is the main cause of failure of semiconductor devices, is the most suitable. The shape of the filler can be spherical, needle-shaped, amorphous, etc., but spherical is preferred, and a perfect sphere is particularly preferred. When the filler is spherical or perfect spherical, filling and dispersion can be performed smoothly.

In addition, the filler may be surface treated with a coupling agent, preferably a silane coupling agent. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyloxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloyloxypropyl)trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-amino Propyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-alkylenepropyltrimethoxysilane, γ-alkylenepropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfide, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, imidazosilane, etc. These can be used alone or in combination of two or more.

Furthermore, the filler species contained in the first region and the filler species contained in the second region may be the same or different. Preferably, they are the same filler species, with silicon oxide being particularly preferred, and synthetic silicon oxide being even more preferred.

When fillers are included in the protective film, the hardness of the protective film after curing is maintained at a high level, while also improving moisture resistance. Furthermore, the thermal expansion coefficient of the cured protective film is brought close to that of the semiconductor wafer, thereby suppressing lifting of the semiconductor wafer during processing and preventing peeling of the protective film after curing.

The curing component can be a thermosetting component, an energy-ray curing component, or a mixture thereof. When using an energy-ray curing component, the light transmittance of the protective film-forming film must be controlled, and a film with a smaller filler content is preferred. Protective film-forming films using thermosetting components do not necessarily require light transmittance control, allowing for a wider range of material choices and are therefore preferred.

Examples of thermosetting components include epoxy resins, phenol resins, melamine resins, urea resins, polyimide resins, benzoxazine resins, and mixtures thereof. Of these, epoxy resins, phenol resins, and mixtures thereof are preferred.

Epoxy resins form a three-dimensional network upon heating, possessing the ability to form a strong coating. While various conventional epoxy resins can be used, those with a molecular weight of approximately 300-2000 are generally preferred, particularly those with a molecular weight of 300-500. Furthermore, a blend of a normally liquid epoxy resin with a molecular weight of 330-400 and a normally solid epoxy resin with a molecular weight of 400-2500, particularly 500-2000, is preferred. Furthermore, the epoxy equivalent weight of the epoxy resin is preferably 50-5000 g/eq.

Specific examples of such epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenyl novolac resin, cresol novolac resin, etc.; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, polypropylene glycol, etc.; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, tetrahydrophthalic acid, etc.; glycidyl ethers of aniline isocyanurate, etc. Epoxy resins of the epoxy or alkyl epoxy type, in which the active hydrogen on the nitrogen atom of a cyclohexane such as isocyanurate is substituted with an epoxy group; so-called alicyclic epoxy resins, in which an epoxy group is introduced by, for example, oxidizing the carbon-carbon double bond within the molecule, such as dicyclohexane, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane (dioxane). Epoxy resins having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, and the like can also be used.

Among these, bisphenol-based epoxy resins, o-cresol novolac-type epoxy resins, and phenol novolac-type epoxy resins are preferred. These epoxy resins can be used alone or in combination of two or more.

When using epoxy resin, it is best to use a heat-activated latent epoxy hardener as an auxiliary agent. Heat-activated latent epoxy hardeners do not react with epoxy resin at room temperature, but are activated by heating above a certain temperature, allowing them to react with the epoxy resin. Methods for activating heat-activated latent epoxy resin hardeners include heating to generate active species (negative and positive ions) through a chemical reaction; stably dispersing the hardener in the epoxy resin at room temperature and then dissolving it at elevated temperatures to initiate the curing reaction; encapsulating the hardener in a molecular sieve, which initiates the curing reaction by dissolving it at elevated temperatures; and using microcapsules.

Specific examples of heat-activated latent epoxy resin hardeners include various onium salts, dibasic acid dihydrazide compounds, dicyandiamide, amine adduct hardeners, and high-melting-point active hydrogen compounds such as imidazole compounds. These heat-activated latent epoxy resin hardeners can be used alone or in combination. The heat-activated latent epoxy resin hardeners are preferably used in an amount of 0.1 to 20 parts by mass, particularly 0.2 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass, per 100 parts by mass of the epoxy resin.

As the phenolic resin, any condensate of a phenol such as alkylphenol, polyvalent phenol, or naphthol with an aldehyde can be used without particular limitation. Specifically, phenol novolac resin, o-cresol novolac resin, p-cresol novolac resin, tertiary butylphenol novolac resin, dicyclopentadiene cresol resin, poly(p-vinylphenol) resin, bisphenol A novolac resin, or modified products thereof can be used.

The phenolic hydroxyl groups in these phenolic resins readily react with the epoxy groups in the epoxy resins mentioned above upon heating, forming a highly impact-resistant cured product. Therefore, epoxy resins and phenolic resins can also be used together.

The binder polymer component imparts appropriate tackiness to the protective film-forming film, thereby improving the operability of the protective film-forming composite sheet 3. The mass average molecular weight of the binder polymer is generally in the range of 50,000 to 2,000,000, preferably 100,000 to 1,500,000, and particularly preferably 200,000 to 1,000,000. When the molecular weight is too low, film formation of the protective film-forming film is insufficient. When the molecular weight is too high, compatibility with other components deteriorates, resulting in obstruction of uniform film formation. Examples of such binder polymers include acrylic polymers, polyester resins, phenoxy resins, urethane resins, silicone resins, and rubber polymers, with acrylic polymers being particularly preferred.

Examples of acrylic polymers include (meth)acrylate copolymers composed of a (meth)acrylate monomer and a constituent unit derived from a (meth)acrylic acid derivative. The (meth)acrylate monomer herein is preferably an alkyl (meth)acrylate having an alkyl group with 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic acid derivatives include (meth)acrylic acid, glycidyl (meth)acrylate, and hydroxyethyl (meth)acrylate.

By introducing glyoxypropyl groups into acrylic polymers using glyoxypropyl methacrylate and other constituent units, compatibility with the thermosetting epoxy resin is improved, raising the glass transition temperature (Tg) of the protective film after curing and improving heat resistance. Furthermore, by introducing hydroxyl groups into acrylic polymers using hydroxyethyl acrylate and other constituent units, adhesion and adhesion properties to the workpiece can be controlled.

When using an acrylic polymer as the binder polymer, the mass average molecular weight of the polymer is preferably 100,000 or higher, particularly preferably 150,000 to 1,000,000. The glass transition temperature of acrylic polymers is generally below 20°C, preferably around -70 to 0°C, and exhibits adhesive properties at room temperature (23°C).

The mixing ratio of the thermosetting component to the adhesive polymer component is preferably 50 to 1500 parts by mass of the thermosetting component per 100 parts by mass of the adhesive polymer component, particularly preferably 70 to 1000 parts by mass, and even more preferably 80 to 800 parts by mass. This ratio of the thermosetting component to the adhesive polymer component provides moderate adhesion before curing, allowing for stable attachment. Furthermore, after curing, a protective film with excellent coating strength is obtained.

The protective film preferably contains a colorant. This improves the legibility and design of the laser printed text.

Colorants that can be used include, for example, known inorganic pigments, organic pigments, and organic dyes. Inorganic pigments include, for example, carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments.

Examples of organic pigments and organic dyes include aminium pigments, cyanine pigments, merocyanine pigments, croconium pigments, squarylium pigments, azulenium pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, phthalocyanine pigments, naphthalocyanine pigments, naphtholactam pigments, and phthalocyanine pigments. aphtholactam), azo dyes, condensed azo dyes, indigo dyes, perinone dyes, perylene dyes, dioxazine dyes, quinacridone dyes, isoindolinone dyes, quinophthalone dyes, pyrrole dyes, thioindigo dyes, metal complex dyes (metal complex dyes), dithiol metal complex dyes, indole dyes (indole Pigments or dyes include phenol, triarylmethane pigments, anthraquinone pigments, dioxazine pigments, naphthol pigments, azomethine pigments, benzimidazolone pigments, pyranthrone pigments, and indanthrene pigments. These pigments or dyes can be mixed appropriately to adjust light transmittance.

Of the above, black pigments are preferred, especially carbon black, as carbon black can block electromagnetic waves over a wide wavelength range.

The amount of colorant (particularly carbon black) added to the protective film-forming film varies depending on the thickness of the protective film. For example, when the protective film thickness is 25 μm, the amount is preferably 0.05 to 1% by mass, particularly 0.075 to 0.75% by mass, and even more preferably 0.1 to 0.5% by mass, relative to the total mass of the protective film-forming film. A colorant amount of 0.05% by mass or greater can effectively mask cutting marks on semiconductor wafers, etc., making them invisible to the naked eye. On the other hand, even if the colorant amount exceeds 1% by mass, the masking properties are barely affected, and excessive amounts can impair adhesion. Furthermore, as the thickness of the protective film-forming film decreases, the light transmittance tends to increase, while as the thickness of the protective film-forming film increases, the light transmittance tends to decrease. Therefore, it is desirable to appropriately adjust the colorant amount according to the thickness of the protective film-forming film. Specifically, it is desirable to adjust the colorant amount so that the thickness of the protective film-forming film and the colorant amount are inversely proportional.

The average particle size of the colorant (especially carbon black) is preferably 1 to 500 nm, particularly 3 to 100 nm, and even more preferably 5 to 50 nm. When the average particle size of the colorant is within this range, it is easier to control the light transmittance within the desired range. The average particle size of the colorant used in this specification is measured by dynamic light scattering using a particle size distribution analyzer (NanoTrac Wave-UT151, manufactured by Nikkiso Co., Ltd.).

Since the colorant is relatively soft and has low hardness, even when cut with a wafer saw, there is little shaking or vibration of the blade, which will not affect the effect of the present invention.

The protective film may also contain a coupling agent. This enhances the adhesion between the protective film and the workpiece, while also improving water resistance (resistance to moisture and heat) after curing without compromising the heat resistance of the protective film. Silane coupling agents are preferred due to their versatility and cost-effectiveness.

As the silane coupling agent, there can be mentioned, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloyloxypropyl)trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)- )-γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-alkylenepropyltrimethoxysilane, γ-alkylenepropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfide, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, imidazole silane, etc. These can be used alone or in combination of two or more.

The protective film-forming film may also contain a crosslinking agent such as an organic polyvalent isocyanate compound, an organic polyvalent imine compound, or an organic metal chelate compound to adjust its cohesive strength before curing. Furthermore, the protective film-forming film may also contain an antistatic agent to suppress static electricity and improve chip reliability. Furthermore, the protective film-forming film may also contain a flame retardant such as a phosphate compound, a bromine compound, or a phosphorus-based compound to enhance the flame retardancy of the protective film and improve the reliability of the package.

The method for producing the protective film-forming film is not particularly limited. When the protective film-forming film is a two-layer product, a first film having a filler diameter that satisfies the first region and a second film having a filler diameter that satisfies the second region may be laminated. This protective film-forming film can be obtained by preparing a coating liquid containing a protective film-forming resin composition containing a filler of a specific particle size and, if necessary, a solvent. The coating liquid is then applied to the release surface of a release sheet using a coating machine such as a roll coater, knife coater, roll knife coater, air knife coater, die coater, rod coater, gravure coater, or curtain coater, followed by drying. A two-layer protective film-forming film can be obtained by preparing two protective film-forming films containing fillers of different particle sizes and laminating them together. When laminating the protective film forming film, hot pressing may be performed.

Furthermore, in the case of having three or more constituent layers, a film containing a filler having a particle size between the filler diameter of the first film and the filler diameter of the second film is prepared, and these layers are layered so that the filler diameter changes stepwise.

By using a coating solution containing multiple fillers, for example, with different specific gravities and particle sizes, single-layer protective film can create a particle size gradient across the thickness of the film. This occurs during the period from coating to drying, when particles of the same specific gravity settle. For example, if a coating solution is prepared that mixes fillers of the same large particle size and specific gravity with fillers of the same small particle size and specific gravity, the larger fillers will settle toward the bottom of the film thickness during the period from coating to drying, while the smaller fillers will tend to accumulate toward the top of the film. This results in a protective film with a continuously varying filler particle size across the thickness of the film.

[Protective Film Sheet] Before use, the protective film is protected on one or both sides with a release sheet. Due to the protective film sheet's form, it can also be rolled up and stored. The release sheet is removed until the protective film is ready for use.

The composition of the release sheet is arbitrary, and examples include a plastic sheet that has release properties for the protective film-forming film, and a plastic sheet that has been stripped using a stripping agent. Specific examples of plastic sheets include polyester sheets such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin sheets such as polypropylene and polyethylene. Silicone-based, fluorine-based, and long-chain alkyl-based release agents can be used. However, silicone-based release agents are preferred because they are inexpensive and offer stable performance. The thickness of the release sheet is not particularly limited, but is typically around 20 to 250 μm.

When a protective film-forming film has release sheets on both sides, it is preferred that the release sheet on one side be a heavy-peel type release sheet with a large release force, and the release sheet on the other side be a light-peel type release sheet with a small release force.

When producing a protective film-forming sheet, a protective film-forming thin film is formed on the release surface (the surface having release properties; usually, but not limited to, the surface subjected to release treatment) of a release sheet by the above-mentioned method.

As an example of how a protective film-forming sheet can be used, the following describes a method for producing a wafer with a protective film from a semiconductor wafer as a workpiece. First, the first surface (first surface) of the protective film-forming thin film of the protective film-forming sheet is attached to the inner surface of a semiconductor wafer that has been subjected to back-grinding and has a circuit formed on its surface. The protective film can be heated as needed to enhance its adhesive properties.

Next, the release sheet is peeled off using the protective film-forming film. The protective film-forming film is then cured to form a protective film, resulting in a semiconductor wafer containing the protective film. Curing the protective film-forming film can also be performed after the dicing step described below.

After obtaining a semiconductor wafer with a protective film as described above, the protective film can be irradiated with laser light to perform laser marking, as needed. This laser marking can be performed before curing the protective film or after the dicing step described below.

Next, the semiconductor wafer with the protective film is cut using a dicing blade according to conventional methods to obtain wafers with the protective film (wafers with the protective film). Afterwards, the dicing blade is expanded in a planar direction as needed, and the wafer with the protective film is picked up from the dicing blade.

The resulting wafer with a protective film has a good appearance because the protective film hides the cut marks caused by backside grinding, making them invisible to the naked eye. Furthermore, the protective film enhances the strength of the wafer and semiconductor wafer, reducing damage during transportation, storage, and processing. Furthermore, since the inner surface of the semiconductor wafer with a protective film is shielded, electromagnetic waves generated within electronic equipment are blocked, reducing semiconductor device failures.

[Protective Film-Forming Composite Sheet] Figure 2 is a cross-sectional view of a protective film-forming composite sheet according to one embodiment of the present invention. As shown in Figure 2, the protective film-forming composite sheet 3 according to this embodiment comprises an adhesive sheet 4 having an adhesive layer 42 formed on one side of a substrate 41, a protective film-forming film 1 laminated on the adhesive layer 42 side of the adhesive sheet 4, and, if necessary, a jig adhesive layer 5 laminated on the edge of the protective film-forming film 1 opposite the adhesive sheet 4. The protective film-forming film 1 has the adhesive layer 41 laminated on its surface (second surface) on the second region side. The jig adhesive layer 5 is a layer for bonding the protective film-forming composite sheet 3 to a jig such as a ring frame.

The protective film-forming composite sheet 3 of the embodiment can be used to maintain the workpiece in contact with the workpiece during machining, while also forming a protective film on the workpiece or a processed product. This protective film can be an uncured protective film-forming film 1, but is preferably formed from a cured product of the protective film-forming film 1.

The protective film forming composite sheet 3 of the embodiment can be used to support a semiconductor wafer as a workpiece during dicing while simultaneously forming a protective film on the resulting semiconductor chips, but is not limited thereto. In this case, the adhesive sheet 4 of the protective film forming composite sheet 3 is generally referred to as a dicing sheet.

1. Adhesive Sheet The adhesive sheet 4 of the protective film-forming composite sheet 3 according to this embodiment comprises a substrate 41 and an adhesive layer 42 laminated on one side of the substrate 41.

1-1. Substrate The substrate 41 of the adhesive sheet 4 can be any material suitable for workpiece processing, such as dicing and expanding semiconductor wafers. Its constituent material is not particularly limited, but it is typically composed of a film primarily composed of a resin-based material (hereinafter referred to as a "resin film").

Specific examples of resin films include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film; polyolefin films such as polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; ethylene copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, and ethylene-(meth)acrylate copolymer film; polyvinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin film. Furthermore, modified films such as crosslinked films and ionomer films may also be used. The substrate 41 may be a film formed of one of the above, or may be a laminated film formed by combining two or more of the above.

Of the above, polyolefin films are preferred from the perspectives of environmental safety and cost, with polypropylene films being particularly preferred due to their excellent heat resistance. Polypropylene films can impart heat resistance to the substrate 41 without compromising the adhesive sheet 4's ability to expand and pick up wafers. This heat resistance of the substrate 41 prevents the adhesive sheet 4 from sagging even when the protective film-forming film 1 is thermally cured while the protective film-forming composite sheet 3 is attached to the workpiece.

The resin film may be subjected to surface treatment, such as oxidation or embossing, or primer treatment, on one or both sides, as needed, to improve adhesion with the adhesive layer 42 deposited thereon. Examples of oxidation methods include coma discharge treatment, plasma discharge treatment, chromium oxide treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation. Examples of embossing methods include sandblasting and flame blasting.

The substrate 41 may also contain various additives such as colorants, flame retardants, plasticizers, antistatic agents, lubricants, fillers, etc. in the resin film.

The thickness of the substrate 41 is not particularly limited as long as it can function appropriately in each step in which the protective film-forming composite sheet 3 is used. It is preferably in the range of 20 to 450 μm, more preferably 25 to 400 μm, and particularly preferably 50 to 350 μm.

The elongation at break of the substrate 41 of the adhesive sheet 4 in this embodiment is preferably 100% or greater, and particularly preferably 200-1000%, as measured at 23°C and a relative humidity of 50%. Elongation at break is defined as the ratio of the length of the test piece at break relative to its original length in a tensile test in accordance with JIS K7161:1994 (ISO 527-1 1993). A substrate 41 with an elongation at break of 100% or greater is less susceptible to fracture during the expansion step, and the resulting wafers are easily separated when the workpiece is cut.

Furthermore, the substrate 41 of the adhesive sheet 4 in this embodiment preferably has a tensile stress of 5 to 15 N/10 mm at 25% deformation, and a maximum tensile stress of 15 to 50 MPa. The tensile stress at 25% deformation and the maximum tensile stress are measured using a test in accordance with JIS K7161:1994. When the tensile stress at 25% deformation is 5 N/10 mm or greater, and the maximum tensile stress is 15 MPa or greater, relaxation of the substrate 41 can be suppressed when the protective film-forming film 1 is attached to a workpiece and then secured to a frame such as a ring frame, thereby preventing transport errors. On the other hand, when the tensile stress at 25% deformation is 15 N/10 mm or less, and the maximum tensile stress is 50 MPa or less, peeling of the adhesive sheet 4 from the ring frame during the expansion step is suppressed. Furthermore, the above-mentioned elongation at break, tensile stress at 25% deformation, and maximum tensile stress are values measured in the longitudinal direction of the original fibers in the substrate 41.

1-2. Adhesive Layer The adhesive layer 42 of the adhesive sheet 4 of the protective film-forming composite sheet 3 according to this embodiment can be composed of either a non-radiation-curing adhesive or a radiation-curing adhesive. Non-radiation-curing adhesives are preferably those that exhibit the desired adhesion and releasability. For example, acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives can be used. Of these, acrylic adhesives are preferred because they exhibit high adhesion to the protective film-forming film 1 and effectively prevent the workpiece or processed object from falling off during dicing.

On the other hand, since the adhesive is energy-ray-curable, the adhesive force is reduced by irradiation with energy rays, so that when the workpiece or processed object is separated from the adhesive sheet 4, it can be easily separated by irradiation with energy rays.

When the adhesive layer 42 is formed of an energy-ray-curable adhesive, the adhesive layer 42 directly below the protective film-forming film in the protective film-forming composite sheet 3 can also be cured. The material cured by the energy-ray-curable adhesive generally has a high modulus of elasticity and a high surface smoothness. Therefore, when the protective film-forming film 1 in contact with the cured portion formed by the material is cured to form a protective film, the surface of the protective film in contact with the cured portion becomes smoother and more glossy, resulting in a more aesthetically pleasing protective film for the chip. Furthermore, when laser engraving is performed on a protective film with a high surface smoothness, the legibility of the printed text is improved. The adhesive layer 42 can also be used for cutting in an uncured state. In this case, since the adhesive force remains high, it is less likely to cause the chip to fly apart during cutting.

The energy-ray-curable adhesive constituting the adhesive layer 42 may be composed mainly of an energy-ray-curable polymer or a mixture of a non-energy-ray-curable polymer and an energy-ray-curable multifunctional monomer and/or oligomer.

The following describes the case where the main component of a radiation-curable adhesive is a polymer having radiation-curable properties.

The radiation-curable polymer is preferably a (meth)acrylate (co)polymer (A) (hereinafter sometimes referred to as "radiation-curable polymer (A)") having radiation-curable functional groups (radiation-curable groups) introduced into the side chains. The radiation-curable polymer (A) is preferably obtained by reacting a (meth)acrylic copolymer (a1) having monomer units containing functional groups with an unsaturated group-containing compound (a2) having a substituent bonded to the functional groups.

The acrylic copolymer (a1) is composed of a constituent unit derived from a functional group-containing monomer and a constituent unit derived from a (meth)acrylate monomer or a derivative thereof.

The functional group-containing monomers constituting the acrylic copolymer (a1) are preferably monomers having a polymerizable double bond and a functional group such as a hydroxyl group, an amino group, a substituted amino group, or an epoxy group in the molecule.

Further specific examples of the functional group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These can be used alone or in combination of two or more.

As the (meth)acrylate monomer constituting the acrylic copolymer (a1), alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms, cycloalkyl (meth)acrylates, and benzyl (meth)acrylates can be used. Among these, alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms are particularly preferred, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

The acrylic copolymer (a1) generally contains constituent units derived from the above-mentioned functional group-containing monomers in a ratio of 3 to 100 mass%, preferably 5 to 40 mass%, and generally contains constituent units derived from (meth)acrylate monomers or derivatives thereof in a ratio of 0 to 97 mass%, preferably 60 to 95 mass%.

The acrylic copolymer (a1) can be obtained by copolymerizing the functional group-containing monomers described above with (meth)acrylate monomers or their derivatives by conventional methods. However, it can also be copolymerized with other monomers besides these monomers, such as dimethylacrylamide, vinyl formate, vinyl acetate, styrene, etc.

The acrylic copolymer (a1) having monomer units containing the above-mentioned functional groups is reacted with the unsaturated group-containing compound (a2) having a substituent bonded to the functional group thereof to obtain an energy radiation curable polymer (A).

The substituent of the unsaturated group-containing compound (a2) can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group is a hydroxyl group, an amino group, or a substituted amino group, the substituent is preferably an isocyanate group or an epoxy group. When the functional group is an epoxy group, the substituent is preferably an amino group, a carboxyl group, or an aziridine group.

In addition, the number of energy-ray-polymerizable carbon-carbon double bonds in the unsaturated group-containing compound (a2) is 1 to 5 per molecule, preferably 1 to 2. Specific examples of such unsaturated group-containing compounds (a2) include 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(diacryloyloxymethyl)ethyl isocyanate; isocyanates obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; Acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound or hydroxyethyl (meth)acrylate; epoxypropyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, and the like.

The unsaturated group-containing compound (a2) is usually used in a ratio of 10 to 100 equivalents, preferably 20 to 95 equivalents, per 100 equivalents of the functional group-containing monomer of the acrylic copolymer (a1).

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, solvent, reaction time, presence or absence of a catalyst, and the type of catalyst can be appropriately selected according to the combination of functional groups and substituents. In this way, the functional groups present in the acrylic copolymer (a1) react with the substituents in the unsaturated group-containing compound (a2), introducing unsaturated groups into the side chains of the acrylic copolymer (a1), thereby obtaining an energy radiation-curable polymer (A).

The mass average molecular weight of the energy radiation curable polymer (A) obtained in this manner is preferably 10,000 or greater, particularly preferably 150,000 to 1,500,000, and even more preferably 200,000 to 1,000,000. The mass average molecular weight (Mw) herein is the polystyrene-equivalent value measured by gel permeation chromatography (GPC).

Even when the energy-curable adhesive contains an energy-curable polymer as a main component, the energy-curable adhesive may further contain an energy-curable monomer and/or oligomer (B).

As the energy beam curable monomer and/or oligomer (B), for example, esters of polyols and (meth)acrylic acid can be used.

Examples of the energy radiation-curable monomer and/or oligomer (B) include monofunctional acrylates such as cyclohexyl (meth)acrylate and isoborneol (meth)acrylate, polyfunctional acrylates such as trihydroxymethylpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dihydroxymethyltricyclodecane di(meth)acrylate, polyester oligo(meth)acrylate, and polyurethane oligo(meth)acrylate.

When the radiation-curable monomer and/or oligomer (B) is formulated, the content of the radiation-curable monomer and/or oligomer (B) in the radiation-curable adhesive is preferably 5 to 80 mass %, particularly preferably 20 to 60 mass %.

Here, when ultraviolet rays are used as the energy rays for curing the energy-curable adhesive, it is preferable to add a photopolymerization initiator (C). By using the photopolymerization initiator (C), the polymerization curing time and the light exposure amount can be reduced.

Specific examples of the photopolymerization initiator (C) include phenyl ketone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoic acid methyl ester, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl benzophenone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, Monosulfide), azobisisobutyronitrile, benzoyl, dibenzoyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2,2-dimethoxy-1,2-diphenylethane-1-one, etc. These may be used alone or in combination of two or more.

The photopolymerization initiator (C) is used in an amount ranging from 0.1 to 10 parts by mass, preferably from 0.5 to 6 parts by mass, based on 100 parts by mass of the radiation-curable copolymer (A) (when the radiation-curable monomer and/or oligomer (B) is prepared, the total amount of the radiation-curable copolymer (A) and the radiation-curable monomer and/or oligomer (B) is 100 parts by mass).

In addition to the above-mentioned components, other suitable components may be added to the energy-ray-curable adhesive. Examples of such other components include a polymer component or oligomer component (D) that is not energy-ray-curable, and a crosslinking agent (E).

Examples of the non-ray-hardenable polymer component or oligomer component (D) include polyacrylates, polyesters, polyurethanes, polycarbonates, and polyolefins, preferably polymers or oligomers having a mass average molecular weight (Mw) of 3,000 to 2,500,000.

As the crosslinking agent (E), a polyfunctional compound reactive with the functional groups of the energy radiation-curable copolymer (A) and the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxides, metal chelate compounds, metal salts, ammonium salts, and reactive phenol resins.

These other components (D), when added to the radiation-curable adhesive (E), can improve the adhesion and releasability before curing, the strength after curing, adhesion to other layers, and storage stability. The amount of these other components added is not particularly limited and can be appropriately determined within the range of 0 to 40 parts by mass relative to 100 parts by mass of the radiation-curable copolymer (A).

Next, the following describes a case where a radiation-curable adhesive has as its main component a mixture of a polymer component that does not have radiation curability and a radiation-curable multifunctional monomer and/or oligomer.

As the non-radiation-hardening polymer component, for example, the same components as those described above for the acrylic copolymer (a1) can be used. The content of the non-radiation-hardening polymer component in the radiation-hardening adhesive is preferably 20 to 99.9% by mass, particularly preferably 30 to 80% by mass.

The radiation-curable multifunctional monomer and/or oligomer can be the same as those used for component (B) above. The ratio of the non-radiation-curable polymer component to the radiation-curable multifunctional monomer and/or oligomer is preferably 10 to 150 parts by mass, and particularly preferably 25 to 100 parts by mass, of the multifunctional monomer and/or oligomer per 100 parts by mass of the polymer component.

Even in this case, the photopolymerization initiator (C) and crosslinking agent (E) can be appropriately formulated as described above.

The thickness of the adhesive layer 42 is not particularly limited as long as it can function appropriately in each step in which the protective film-forming composite sheet 3 is used. Specifically, it is preferably 1 to 50 μm, particularly preferably 2 to 30 μm, and even more preferably 3 to 20 μm.

The adhesive constituting the jig adhesive layer 5 preferably has the desired adhesion and releasability. Examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, acrylic adhesives are preferred because they offer high adhesion to jigs such as ring frames and effectively prevent the protective film-forming composite sheet 3 from peeling off the ring frame during the cutting process. Furthermore, a base material serving as a core material may be interposed within the thickness direction of the jig adhesive layer 5.

On the other hand, the thickness of the jig adhesive layer 5 is preferably 5 to 200 μm, particularly 10 to 100 μm, for jigs such as ring frames from the perspective of adhesion.

2. Method for Manufacturing a Protective Film-Forming Composite Sheet The protective film-forming composite sheet 3 is preferably manufactured by separately preparing a first laminate comprising the protective film-forming film 1 and a second laminate comprising the adhesive sheet 4. The first and second laminates are then used to laminate the protective film-forming film 1 and the adhesive sheet 4. However, the present invention is not limited to this method. As described above, the second surface of the protective film-forming film 1 is laminated so that the second surface contacts the adhesive layer of the adhesive sheet.

When producing the first laminate, the protective film-forming thin film 1 is formed on the release surface of the release sheet by the above-mentioned method. For example, in the case of a two-layer protective film, a coating liquid for the protective film is prepared containing a resin composition comprising a first film and a second film constituting the protective film 1, and optionally a solvent. The coating liquid is applied to the release surface of a release sheet using a coating machine such as a roll coater, a knife coater, a roll knife coater, an air knife coater, a die coater, a rod coater, a gravure coater, or a curtain coater. The coating is then dried to form the first and second films, which are then laminated together to form the protective film 1. Sometimes, there are peeling sheets on both sides of the protective film forming film 1 (the first laminate). In this case, it is best to use a heavy-peel type peeling sheet with a relatively strong peeling force as the peeling sheet on the first film side, and a light-peel type peeling sheet with a relatively weak peeling force as the peeling sheet on the second film side.

The first laminate can be cut as needed to form the protective film-forming film 1 (and the peeling sheet with a light peel force) into a desired shape, such as a circle. Excess portions of the protective film-forming film 1 and the peeling sheet resulting from the cutting process can be removed as needed.

Meanwhile, when manufacturing the second laminate, an adhesive coating liquid containing an adhesive constituting adhesive layer 42 and, if necessary, a solvent is applied to the release surface of the release sheet and dried to form adhesive layer 42. Subsequently, substrate 41 is pressed against the exposed surface of adhesive layer 42, resulting in a laminate (second laminate) consisting of adhesive sheet 4 composed of substrate 41 and adhesive layer 42, and the release sheet.

Here, when the adhesive layer 42 is formed of an energy-ray-curable adhesive, the adhesive layer 42 may be cured after the protective film-forming film 1 is deposited on the adhesive layer 42. Furthermore, the protective film-forming film 1 and the deposited adhesive layer 42 may be cured before the cutting step, but preferably, the adhesive layer 42 may be cured after the cutting step.

Energy rays such as ultraviolet rays and electron rays are commonly used. While the irradiation dose varies depending on the type of energy ray, for example, in the case of ultraviolet rays, the dose is preferably 50 to 1000 mJ/ ^cm² , particularly 100 to 500 mJ/ ^cm² . Electron rays are preferably 10 to 1000 krad.

With the first and second laminates thus obtained, the lightly peelable release sheet in the first laminate is peeled off, exposing the second film-side surface (second surface) of the protective film-forming film 1. Simultaneously, the release sheet in the second laminate is peeled off, so that the second film-side surface of the protective film-forming film 1 exposed in the first laminate is superimposed and pressed against the adhesive layer 42 of the adhesive sheet 4 exposed in the second laminate. The adhesive sheet 4 is cut as needed to a desired shape, such as a circular shape having a larger diameter than the protective film-forming film 1. Any excess adhesive sheet 4 resulting from the cutting process can be removed as needed.

In this way, a protective film-forming composite sheet 3 is obtained, which comprises an adhesive sheet 4 formed by laminating an adhesive layer 42 on a substrate 41; a protective film-forming film 1 laminated on the adhesive layer 42 side of the adhesive sheet 4; and a releasable release sheet laminated on the side of the protective film-forming film 1 opposite the adhesive sheet 4. If desired, a ring-shaped jig adhesive layer 5 can be formed on the edge of the exposed protective film-forming film 1 after peeling off the releasable release sheet. The jig adhesive layer 5 can also be formed by applying and cutting in the same manner as the adhesive layer 42 described above. When adhesive layer 42 is formed of a radiation-hardening adhesive, jig adhesive layer 5 is not necessarily required to ensure sufficient adhesion before curing. When adhesive layer 42 is formed of a non-radiation-hardening adhesive with low adhesion, jig adhesive layer 5 is preferably provided to secure jigs such as ring frames.

3. Method of Using the Composite Sheet for Forming a Protective Film As an example of how to use the composite sheet for forming a protective film according to this embodiment, the following describes a method for obtaining a protective film-containing fragment, such as a semiconductor chip, from a workpiece such as a semiconductor wafer. The manufacturing method includes the following steps (1) to (4); Step (1): a step of attaching the surface (first surface) of the protective film forming film 1 of the protective film forming sheet 3 on the first area side to the inner surface of the workpiece 6; Step (2): a step of heating and curing the protective film forming film 1 to obtain a protective film; Step (3): a step of cutting the workpiece 6 and the protective film forming film or protective film to obtain single-piece segments of the same shape and a laminate of the protective film forming film or protective film; and Step (4): a step of separating the protective film forming film or protective film from the adhesive sheet. Furthermore, the steps after step (1) may be in the order of steps (2), (3), and (4), or in the order of steps (3), (2), and (4), or in the order of steps (3), (4), and (2).

The following is a detailed description of the method for manufacturing a segment containing a protective film. The following description will be given, in particular, by taking the case where the workpiece 6 is a semiconductor wafer and the segment obtained is a semiconductor chip containing a protective film as an example. As shown in FIG4 , the protective film forming film 1 of the protective film forming sheet 3 is attached to the inner surface of the semiconductor wafer 6 (step (1)). At this time, the outer periphery of the protective film forming film 1 can also be fixed by the ring frame 7. In addition, when the jig adhesive layer 5 is provided, the jig adhesive layer 5 is attached to the ring frame 7. The inner surface of the semiconductor wafer 6 is attached to the first film side surface (first surface) of the protective film forming film 1. The protective film forming film 1 is attached to the semiconductor wafer 6 and the protective film forming film 1 may be heated as needed to enhance the adhesiveness.

Thereafter, the protective film forming film 1 is cured to form a protective film (step (2)), thereby obtaining a semiconductor wafer 6 containing a protective film. When the protective film forming film 1 is thermosetting, the protective film forming film 1 only needs to be heated at a specific temperature for an appropriate time. Furthermore, the protective film forming film 1 can be cured after the dicing step, or after the semiconductor wafer containing the protective film forming film is picked up from the adhesive sheet and then cured.

As described above, a semiconductor wafer 6 having a protective film is obtained. If necessary, the protective film is irradiated with laser light through the adhesive sheet 4 to perform laser marking. Furthermore, this laser marking can be performed before the protective film forming film 1 is cured. Laser marking is performed on the surface (second surface) of the protective film forming film or the second region side of the protective film.

Next, the semiconductor wafer 6 containing the protective film is cut according to a conventional method to obtain a chip with a protective film (a chip containing a protective film) (step (3)). Thereafter, the adhesive sheet 4 is expanded in a planar direction as needed, and the chip containing the protective film is picked up from the adhesive sheet 4 (step (4)).

The resulting wafer with a protective film has a good appearance because the protective film hides the cutting marks caused by backside grinding, making them invisible. Furthermore, the protective film enhances the strength of the wafer and semiconductor wafer, reducing damage during transportation, storage, and processing. Furthermore, since the inner surface of the semiconductor wafer with a protective film is shielded, electromagnetic waves generated within electronic equipment are blocked, reducing semiconductor device failures.

4. Other Embodiments of the Protective Film-Forming Composite Sheet Figure 3 is a cross-sectional view of a protective film-forming composite sheet according to another embodiment of the present invention. As shown in Figure 3, the protective film-forming composite sheet 3A according to this embodiment comprises an adhesive sheet 4 having an adhesive layer 42 formed on one side of a substrate 41, and a protective film-forming film 1 laminated on the adhesive layer 42 side of the adhesive sheet 4. In this embodiment, the protective film-forming film 1 is substantially the same size as the workpiece when viewed from above, but can be formed slightly larger than the workpiece and smaller than the adhesive sheet 4. The portion of the adhesive layer 42 not laminated with the protective film 1 can be attached to a jig such as a ring frame.

The materials and thicknesses of the various components of the protective film-forming composite sheet 3A according to this embodiment are the same as those of the aforementioned protective film-forming composite sheet 3. However, when the adhesive layer 42 is formed of a radiation-curable adhesive, it is preferred that the radiation-curable adhesive be cured in the portion of the adhesive layer 42 that contacts the protective film-forming film 1, while the remaining portions remain uncured. This ensures that the smoothness and glossiness of the cured protective film 1 are enhanced, while maintaining high adhesion to jigs such as ring frames.

Furthermore, a jig adhesive layer similar to the jig adhesive layer 5 of the protective film forming composite sheet 3 may be additionally provided on the edge of the adhesive layer 42 of the adhesive sheet 4 of the protective film forming composite sheet 3A.

The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, all design changes and equivalents of the elements disclosed in the embodiments described above within the technical field to which the present invention belongs are included in the spirit of the present invention.

For example, a release sheet may be laminated on the protective film-forming film 1 side of the protective film-forming composite sheet 3 or the protective film-forming composite sheet 3A to protect the protective film-forming film until use. [Example]

Hereinafter, the present invention will be further described in detail with reference to embodiments and the like; however, the scope of the present invention is not limited to these embodiments and the like.

[Example 1] (Preparation of a thin film for forming a protective film) The following components were mixed in the ratio (solid content conversion) shown in Table 1, diluted with methyl ethyl ketone so that the solid content concentration became 61% by mass, and prepared coating liquids 1 to 4 for forming a thin film for forming a protective film. (a) Binder polymer: a (meth)acrylate copolymer obtained by copolymerizing 9 parts by mass of n-butyl acrylate, 71 parts by mass of methyl acrylate, 6 parts by mass of glycidyl methacrylate, and 14 parts by mass of 2-hydroxyethyl acrylate (mass average molecular weight: 800,000, glass transition temperature: -1°C) (b) Thermosetting component (b-1) Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184 to 194 g/eq) (b-2) Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1055, epoxy equivalent 800 to 900 g/eq) (b-3) Dicyclopentadiene epoxy resin (manufactured by DIC Corporation, EPICLON HP-7200HH, epoxy equivalent 255~260g/eq) (c) Thermally active latent epoxy resin hardener: dicyandiamide (ADEKA hardener EH-3636AS, active hydrogen content 21g/eq) (d) Curing accelerator: 2-phenyl-4,5-dihydroxymethylimidazole (Shikoku Chemical Industries, Ltd., curezol 2PHZ) (e) Colorant: carbon black (MA600B, Mitsubishi Chemical Corporation, average particle size 20nm) (f) Silane coupling agent (Shin-Etsu Chemical, KBM403) The following four types were used as silica fillers. Coating Liquid 1 used a silica filler (g-1), Coating Liquid 2 used a silica filler (g-2), Coating Liquid 3 used a silica filler (g-3), and Coating Liquid 4 used a silica filler (g-4). In the following, Dmax' represents the maximum diameter of the raw material filler, and _D50 ' represents the 50% cumulative diameter of the raw material filler. (g-1) Silica filler (manufactured by Admatechs, SC4050-MMQ, Dmax': 5 μm, D ₅₀ ': 1.0 μm) (g-2) Silica filler (manufactured by Admatechs, SC2050-MA, Dmax': 2 μm, D ₅₀ ': 0.5 μm) (g-3) Silica filler (manufactured by Admatechs, SC105G-MMQ, Dmax': 1.5 μm, D ₅₀ ': 0.3 μm) (g-4) Silica filler (manufactured by Admatechs, YA050C-MJE, Dmax': 0.2 μm, D ₅₀ ': 0.05 μm)

In this specification, the particle sizes (maximum diameter Dmax' and 50% cumulative diameter _D50 ') of raw material fillers are values measured using a dynamic light scattering method using a particle size distribution analyzer (Nikkiso Co., Ltd., NanoTrac Wave-UT151) for fillers with _{a D50} ' of less than 1 μm. Furthermore, values measured using a laser diffraction-scattering method using a particle size distribution analyzer (Nikkiso Co., Ltd., Microtrac MT3000II) for fillers with a D50' of 1 μm or greater are shown in the table below. The blending ratios (parts by mass) of the components in coating solutions 1-4 are shown in the table below.

[Table 1] Element Coating 1 Coating 2 Coating 3 Coating liquid 4 Binder polymer a-1 150 150 150 150 Thermosetting ingredients b-1 60 60 60 60 b-2 10 10 10 10 b-3 30 30 30 30 Hardener c 2 2 2 2 Hardening accelerator d 2 2 2 2 Colorant e 2.0 2.0 2.0 2.0 coupling agent f 2 2 2 2 filler g-1 320 g-2 320 g-3 320 g-4 320

A first release sheet (SP-PET3811, manufactured by LINTEC, with a thickness of 38 μm) having a silicone release agent layer formed on one side of a polyethylene terephthalate (PET) film and a second release sheet (SP-PET381031, manufactured by LINTEC, with a thickness of 38 μm) having a silicone release agent layer formed on one side of a PET film were prepared.

The above coating liquid was applied to the release surface of the first release sheet using a knife coater, with the final filler-containing film thickness reaching 7 μm. The film was then dried in an oven at 120°C for 2 minutes to prepare a filler-containing film. The filler-containing film obtained by applying coating liquid 1 was designated as film 1. Coating liquids 2 to 4 were applied in the same manner to form films 2 to 4, respectively.

The second release sheet was peeled off from the resulting film, exposing one side of the film. The films were then heat-pressed at 70°C to produce a protective film-forming film having the two-layer structure shown below. Protective film-forming film (1/2): A laminate of film 1 and film 2 Protective film-forming film (1/3): A laminate of film 1 and film 3 Protective film-forming film (1/4): A laminate of film 1 and film 4 Protective film-forming film (2/3): A laminate of film 2 and film 3 Protective film-forming film (2/4): A laminate of film 2 and film 4 Protective film-forming film (1/1): A laminate of film 1 and film 2 Protective film-forming film (4/4): A laminate of film 4 and film 4 Protective film-forming film (1/1) and protective film-forming film (4/4) are substantially single-layer films. The protective film was cut into a 200 mm diameter film having the same shape as the silicon wafer to be attached.

(Adhesive Sheet Preparation) The following energy-ray-curable acrylic copolymer was used as the main agent for the adhesive layer. An acrylic polymer copolymerized from 80 parts by mass of 2-ethylhexyl acrylate (2EHA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA) was reacted with 2-methacryloyloxyethyl isocyanate (hereinafter abbreviated as "MOI") (the total molar number of isocyanate groups in MOI being 80% of the total molar number of hydroxyl groups derived from HEA in the acrylic polymer). The resulting energy-ray-curable acrylic copolymer has a mass-average molecular weight of 800,000 and a glass transition temperature of -10°C, and has methacryloyl groups on its side chains.

100 parts by mass of the above-mentioned energy-ray-curable acrylic copolymer, 3 parts by mass of Irgacure 184 (manufactured by BASF) as a photopolymerization initiator, 3 parts by mass of Irgacure 127 (manufactured by BASF), and 6 parts by mass of coronate L (manufactured by TOSOH, a phenylene diisocyanate-based crosslinking agent) as a crosslinking agent were mixed in a solvent to obtain a coating solution of the adhesive composition.

The resulting adhesive composition coating solution was applied using a knife coater to the release-treated surface of a polyethylene terephthalate film (LINTEC SP-PET381031, 38 μm thick) that had been treated on one side with a silicone release agent. The coating was then heated at 100°C for 1 minute to form a 20 μm thick adhesive layer.

The resulting adhesive layer was attached to a polypropylene substrate having a thickness of 80 μm. The release sheet was then removed to obtain an adhesive sheet. The resulting adhesive sheet was then cut into circular shapes with a diameter of 330 mm to obtain cut sheets.

(Measurement of Filler Particle Size in a Cross-Section of a Protective Film-Forming Film) A protective film-forming film was heated at 130°C for 2 hours to cure. The cured protective film was cut and the cross-section was polished under the following conditions. Polishing Conditions: Apparatus: Polishing apparatus (Refine Tec, product name: Refine Polisher-HV) Polishing: Refine Tec, abrasive polishing, suede cloth Polishing agent: Musashi Holts Co., Ltd., aluminum oxide particle dispersion MH159 Polishing speed: 200 rpm Polishing load: 1 N The polished surface was observed using a KEYENCE VE-9800 to determine the maximum filler diameter (Dmax) and cumulative diameter ( _D50) . The polished surface was observed until 30 fillers were identified in each of the following areas. Cross-sectional observations were performed in the following areas: Area 1: The area from the surface on one side to a depth of 0.2T when the total thickness of the protective film-forming film is T. Area 2: The area from the surface on the other side to a depth of 0.2T when the total thickness of the protective film-forming film is T. The filler diameter obtained from cross-sectional observation was calculated as the circle-equivalent diameter. For convenience, the area with the smaller cumulative diameter _D50 is referred to as the "area 1."

The maximum filler diameter Dmax and cumulative diameter _D50 in each region of the prepared multilayer protective film are shown below. Protective film-forming film (1/1) and protective film-forming film (4/4) are substantially single-layer films, and the maximum filler diameter Dmax and cumulative diameter _D50 are the same in the first and second regions.

[Table 2] 1st area (μm) Second area (μm) (D ₅₀ 2-D ₅₀ 1)/D ₅₀ l×100 (Dmax2-Dmax1)/Dmax1×100 D ₅₀ 1 Dmax1 D ₅₀ 2 Dmax2 Protective film forming film (1/2) 0.49 1.60 1.10 3.80 124 138 Protective film forming film (1/3) 0.50 1.60 1.10 4.00 120 150 Protective film forming film (1/4) 0.05 0.10 0.90 4.20 1700 4100 Film for forming protective film (2/3) 0.34 1.40 0.50 1.70 47 twenty one Protective film forming film (2/4) 0.05 0.08 0.48 1.90 860 2275 Protective film forming film (1/1) 1.10 4.00 1.10 4.00 0 0 Protective film forming film (4/4) 0.05 0.10 0.05 0.10 0 0

(Example 1) The surface of the first region of the protective film-forming film (1/2) (the surface of film 2) was attached to the polished surface of a silicon wafer (200 mm diameter, 280 μm thickness) that had been polished using a #2000 polishing machine (RAD-3600 F/12, manufactured by LINTEC Corporation) while being heated at 70°C. Next, the adhesive layer of the dicing sheet prepared above was attached to the surface of the second region of the protective film-forming film (the surface of film 1). Furthermore, the outer periphery of the adhesive layer was fixed to a ring frame. The laminated product of the silicon wafer, protective film-forming film (1/2), and dicing sheet was heated at 130°C for 2 hours to cure the protective film-forming film, thereby forming a protective film on the polished surface of the silicon wafer.

A silicon wafer with a protective film attached to a dicing blade was diced using a dicing device (Disco Corporation's "DFD6362") to obtain 5 mm x 5 mm wafers with a protective film. Cutting conditions were as follows: Wafer dicing blade movement speed: 50 mm/s Wafer dicing blade rotation speed: 30,000 rpm

(Crack Evaluation) After the dicing step, the base surface of the diced sheet was irradiated with UV light. After the adhesive cured, two wafers were picked from the center of the wafer. Additionally, two wafers were picked from four locations approximately 20 mm from the center of the wafer along two straight lines perpendicular to the center of the wafer. The presence and length of streak-like cracks (chipping) occurring along the polished surface in the thickness direction of the wafer were examined using an electron microscope (KEYENCE VE-9800). The maximum length of the cracks occurring on the ten wafers was evaluated according to the following criteria: S: Maximum length less than 10 μm A: Maximum length 10 μm or more but less than 15 μm B: Maximum length 15 μm or more but less than 30 μm F: Maximum length 30 μm or more

Example 2 The same procedure as Example 1 was followed, except that the first region of the protective film (1/3) (the surface of film 3) was attached to the silicon wafer, and the second region (the surface of film 1) was attached to the dicing sheet. The results are shown in Table 3.

Example 3 The same procedure as Example 1 was followed, except that the first region of the protective film (1/4) (the surface of film 4) was attached to the silicon wafer, and the second region (the surface of film 1) was attached to the dicing sheet. The results are shown in Table 3.

Example 4 The same procedures as in Example 1 were followed, except that the first region of the protective film (2/3) (the surface of film 3) was attached to the silicon wafer, and the second region (the surface of film 2) was attached to the dicing sheet. The results are shown in Table 3.

(Example 5) The same procedure as in Example 1 was followed, except that the first region of the protective film (2/4) (the surface of film 4) was attached to the silicon wafer, and the second region (the surface of film 2) was attached to the dicing sheet. The results are shown in Table 3.

(Example 6) The procedure was the same as in Example 1, except that a dicing sheet was pre-attached to the protective film-forming film (1/2). Specifically, the adhesive layer of the prepared dicing sheet was attached to the second region side surface (film 1 surface) of the protective film-forming film (1/2). Next, the first region side surface (film 2 surface) was attached to the polished surface of a #2000 polished silicon wafer (200 mm diameter, 280 μm thickness) using a tape bonder (LINTEC Corporation, RAD-3600 F/12) while heating at 70°C. The remaining steps were the same as in Example 1.

(Comparative Example 1) Except for using a protective film-forming film (1/1), the remainder of the process was the same as in Example 1. The results are shown in Table 3.

(Comparative Example 2) Except for using a protective film-forming film (4/4), the remainder of the process was the same as in Example 1. The results are shown in Table 3.

(Reference Example 1) The same procedures as in Example 1 were followed, except that the second region of the protective film (1/4) (the surface of film 1) was attached to the silicon wafer, and the first region (the surface of film 4) was attached to the dicing sheet. The results are shown in Table 3.

(Reference Example 2) The same procedures as in Example 1 were followed, except that the second region of the protective film (2/3) (the surface of film 2) was attached to the silicon wafer, and the first region (the surface of film 3) was attached to the dicing sheet. The results are shown in Table 3.

[Table 3] Surface of protective film forming film to be attached Collapse Evaluation silicon wafer side cutting blade side Example 1 Area 1 Area 2 A _D50 : 0.49μm _D50 : 1.10μm Example 2 Area 1 Area 2 S _D50 : 0.50μm _D50 : 1.10μm Example 3 Area 1 Area 2 S _D50 : 0.05μm _D50 : 0.90μm Example 4 Area 1 Area 2 S _D50 : 0.34μm _D50 : 0.50μm Example 5 Area 1 Area 2 S _D50 : 0.05μm _D50 : 0.48μm Comparative example 1 Single layer film B _D50 : 1.10μm Comparative example 2 Single layer film F _D50 : 0.05μm Reference Example 1 Area 2 Area 1 F _D50 : 0.90μm _D50 : 0.05μm Reference Example 2 Area 2 Area 1 F _D50 : 0.50μm _D50 : 0.34μm

As shown in Table 3, by attaching the first region containing fillers with relatively small particle sizes to the semiconductor wafer side and the second region containing fillers with relatively large particle sizes to the dicing blade side, the laminate of the semiconductor wafer and the protective film-forming thin film can be cut with a wafer dicing blade, suppressing blade shake and vibration, thereby reducing chipping. [Industrial Applicability]

The protective film-forming film and the protective film-forming composite sheet according to the present invention are particularly suitable for producing segments (semiconductor chips, etc.) having a protective film from workpieces such as semiconductor wafers, and can particularly contribute to reducing chipping.

1: Protective film forming film 2: Filler 3, 3A: Protective film forming composite sheet 4: Adhesive sheet 41: Base material 42: Adhesive layer 5: Jig adhesive layer 6: Workpiece (semiconductor wafer) 7: Ring frame

[Figure 1] is a schematic diagram of a partial cross-section of a protective film-forming film according to one embodiment of the present invention. [Figure 2] is a cross-sectional view of a protective film-forming composite sheet according to one embodiment of the present invention. [Figure 3] is a cross-sectional view of a protective film-forming composite sheet according to another embodiment of the present invention. [Figure 4] is a cross-sectional view illustrating an example of the use of the protective film-forming composite sheet according to one embodiment of the present invention.

1: Film for forming a protective film

2: Filler

T:Total thickness

Claims (7)

A protective film-forming film containing a filler, wherein, in cross-sectional observation of the film, when the total thickness of the film is T, a first region is defined as a region from the surface of one side of the film to a depth of 0.2T, and a second region is defined as a region from the surface of the other side of the film to a depth of 0.2T. A 50% cumulative diameter D ₅₀ 1 of the filler observed in the first region and a 50% cumulative diameter D ₅₀ 2 of the filler observed in the second region satisfy the following: D ₅₀ 1 < D ₅₀ 2, and 10000 > (D ₅₀ 2 - D ₅₀ 1)/D ₅₀ 1 × 100 ≧ 5 (%); D 50 1 is in the range of 0.01 to 2 μm, _{and D 50 2} is in the range of 0.01 to 3 μm. The protective film-forming film according to claim 1 comprises two or more constituent layers. The protective film-forming film according to claim 1, wherein the filler is an inorganic filler. The protective film-forming film according to claim 3, wherein the inorganic filler is a silicon oxide filler. A film for forming a protective film as claimed in any one of claims 1 to 4, wherein the surface on the side of the first region is attached to a workpiece. A composite sheet for forming a protective film comprises: an adhesive sheet formed by laminating a substrate and an adhesive layer; and a protective film-forming film according to any one of claims 1 to 5 laminated on the adhesive layer side of the adhesive sheet. The protective film-forming film is laminated on the surface of the second region side of the protective film. A method for manufacturing a fragment containing a protective film, comprising the following steps (1) to (4): Step (1): a step of attaching the surface of the first region side of the protective film forming film of the protective film forming composite sheet of claim 6 to a workpiece; Step (2): a step of heating and curing the protective film forming film to obtain a protective film; Step (3): a step of cutting a semiconductor wafer and a protective film forming film or a protective film to obtain single-chip fragments of the same shape and a laminate of the protective film forming film or the protective film; and Step (4): a step of separating the protective film forming film or the protective film from the adhesive sheet.