JP6838018B2 - Protective film forming film, protective film forming sheet and inspection method - Google Patents

Description

The present invention relates to a protective film forming film and a protective film forming (composite) sheet capable of forming a protective film on a work such as a semiconductor wafer or a processed product obtained by processing the work (for example, a semiconductor chip), and the same. It relates to an inspection method for inspecting a workpiece or a work piece with a protective film obtained by using.

In recent years, semiconductor devices have been manufactured by a mounting method called a face-down method. In this method, when mounting a semiconductor chip having a circuit surface on which electrodes such as bumps are formed, the circuit surface side of the semiconductor chip is joined to a chip mounting portion such as a lead frame. Therefore, the structure is such that the back surface side of the semiconductor chip on which the circuit is not formed is exposed.

Therefore, in order to protect the semiconductor chip, a protective film made of a hard organic material is often formed on the back surface side of the semiconductor chip. This protective film is formed by using, for example, a semiconductor back surface film or a dicing tape integrated wafer back surface protective film as shown in Patent Document 1 or 2.

In the film for the back surface of the semiconductor in Patent Document 1, the light transmittance at a wavelength of 532 nm or 1064 nm is set to 20% or less. This enables printing processing by irradiating the laser beam and prevents the adverse effect of the laser beam from affecting the semiconductor element. Further, in the wafer back surface protective film in Patent Document 2, the visible light transmittance is set to 20% or less. As a result, the influence of the passage of light rays on the semiconductor element is reduced.

Japanese Unexamined Patent Publication No. 2012-28396 Japanese Unexamined Patent Publication No. 2012-235168

By the way, in a semiconductor chip or the like obtained by dicing a semiconductor wafer, cracks or the like may occur due to stress generated during processing. However, when the protective film having the light transmittance as described above is formed, cracks and the like generated on the protective film side of the semiconductor chip cannot be visually detected. Semiconductor chips with cracks that cannot be overlooked reduce the product yield.

On the other hand, on the back surface of the semiconductor chip, grinding marks usually left by back grind processing applied to the semiconductor wafer. From the viewpoint of the appearance of the semiconductor chip, it is desirable that the grinding marks are not visually visible, and it is desirable that the grinding marks are concealed by the protective film described above.

The present invention has been made in view of the above-mentioned actual conditions, and it is possible to inspect cracks and the like existing in the work or the work piece obtained by processing the work piece, and it exists in the work piece or the work piece. Inspect a protective film forming film and a protective film forming (composite) sheet capable of forming a protective film in which grinding marks are not visually visible, and a workpiece or work piece with a protective film obtained by using them. The purpose is to provide an inspection method.

In order to achieve the above object, first, the present invention provides a protective film-forming film characterized in that the light transmittance at a wavelength of 1600 nm is 25% or more and the light transmittance at a wavelength of 550 nm is 20% or less. Provided (Invention 1).

According to the above invention (Invention 1), it is possible to inspect the work or the work piece obtained by processing the work piece by infrared rays, and the grinding marks existing on the work piece or the work piece can be visually inspected. No protective film can be formed.

In the above invention (Invention 1), the protective film-forming film is preferably a single layer composed of an uncured curable adhesive (Invention 2).

In the above invention (Invention 2), the curable adhesive preferably contains a colorant and a filler having an average particle size of 0.01 to 3 μm (Invention 3).

Secondly, the present invention is provided with the protective film-forming film (Inventions 1 to 3) and a release sheet laminated on one surface or both sides of the protective film-forming film for forming a protective film. A sheet is provided (Invention 4).

Thirdly, the present invention provides a protective film including a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is laminated on one surface side of a base material and a protective film-forming film laminated on the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. The forming composite sheet is characterized in that the protective film forming film has a light transmittance of 25% or more at a wavelength of 1600 nm and the protective film forming film has a light transmittance of 10% or less at a wavelength of 550 nm. A composite sheet for forming a protective film is provided (Invention 5).

According to the above inventions (Inventions 4 and 5), it is possible to inspect the work or the work piece obtained by processing the work piece by infrared rays, and the grinding marks existing on the work piece or the work piece can be visually inspected. Can form an invisible protective film.

In the above invention (Invention 5), the protective film-forming film is preferably a single layer composed of an uncured curable adhesive (Invention 6).

In the above invention (Invention 6), the curable adhesive preferably contains a colorant and a filler having an average particle size of 0.01 to 3 μm (Invention 7).

Fourth, the present invention protects the work by using the protective film forming film (inventions 1 to 3), the protective film forming sheet (invention 4), or the protective film forming composite sheet (inventions 5 to 7). A work with a protective film is manufactured by forming a film, and the work with the protective film or the work piece obtained by processing the work with the protective film is inspected through the protective film using infrared rays. Provided is an inspection method characterized by performing (Invention 8).

In the above invention (Invention 8), it is preferable that the work is a semiconductor wafer and the work piece is a semiconductor chip (Invention 9).

Fifth, the present invention provides a work with a protective film judged to be a non-defective product based on the inspection method (Invention 8 and 9) (Invention 10).

Sixth, the present invention provides a processed product judged to be a non-defective product based on the inspection method (Invention 8 and 9) (Invention 11).

According to the protective film forming film and the protective film forming (composite) sheet according to the present invention, it is possible to inspect the work or the work piece obtained by processing the work with infrared rays such as cracks, and the work or the work or the work. It is possible to form a protective film in which the grinding marks existing on the work piece are not visually visible. Further, according to the inspection method according to the present invention, it is possible to inspect cracks and the like existing in a work or a work piece by using infrared rays.

It is sectional drawing of the protective film forming sheet which concerns on one Embodiment of this invention. It is sectional drawing of the composite sheet for forming a protective film which concerns on one Embodiment of this invention. It is sectional drawing of the composite sheet for forming a protective film which concerns on other embodiment of this invention. It is sectional drawing which shows the use example of the composite sheet for forming a protective film which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Protective film forming film]
The protective film-forming film according to the present embodiment is for forming a protective film on a work or a work piece obtained by processing the work. This protective film is composed of a protective film-forming film, preferably a cured protective film-forming film. Examples of the work include semiconductor wafers, and examples of the work piece obtained by processing the work include semiconductor chips, but the present invention is not limited thereto. When the work is a semiconductor wafer, the protective film is formed on the back surface side of the semiconductor wafer (the side on which electrodes such as bumps are not formed).

1. 1. Physical Properties The protective film-forming film according to the present embodiment has a light transmittance of 25% or more at a wavelength of 1600 nm and a light transmittance of 20% or less at a wavelength of 550 nm. The light transmittance in the present specification is a value measured without using an integrating sphere, and a spectrophotometer is used as the measuring instrument.

In a semiconductor chip or the like obtained by dicing a semiconductor wafer, cracks or the like may occur due to stress generated during processing. When the light transmittance at a wavelength of 1600 nm is 25% or more as described above, the infrared ray transmittance becomes good, and infrared rays are acquired from the protective film forming film (or the protective film formed by the protective film forming film) side. Infrared inspection can be performed. As a result, cracks and the like in the work piece such as a semiconductor chip can be found through the protective film forming film (protective film), and the product yield can be improved.

From the viewpoint of infrared transmittance, the light transmittance of the protective film forming film at a wavelength of 1600 nm is preferably 40% or more, particularly preferably 45% or more, and further preferably 50% or more. .. The upper limit of the light transmittance at a wavelength of 1600 nm is not particularly limited, but it is naturally determined by setting the light transmittance at a wavelength of 550 nm to 20% or less. Further, when a work piece (semiconductor chip, etc.) on which a protective film is formed is used, the light transmittance of the protective film forming film at a wavelength of 1600 nm is set to 90% or less, so that the work piece is easily affected by infrared rays from the outside. It is possible to prevent malfunction.

On the other hand, for example, on the back surface of a semiconductor chip, grinding marks due to back grind processing applied to a semiconductor wafer are usually left. When the light transmittance at a wavelength of 550 nm is 20% or less as described above, the protective film-forming film becomes difficult to transmit visible light. Therefore, the above-mentioned grinding marks are hidden by the protective film forming film (protective film) and are almost invisible to the naked eye. As a result, the appearance of the processed product such as a semiconductor chip becomes excellent.

From the viewpoint of hiding the grinding marks, the light transmittance of the protective film forming film at a wavelength of 550 nm is preferably 15% or less, and particularly preferably 10% or less. The lower limit of the light transmittance at a wavelength of 550 nm is not particularly limited, but it is naturally determined by setting the light transmittance at a wavelength of 1600 nm to 25% or more.

Here, the protective film-forming film according to the present embodiment may be composed of a single layer or a plurality of layers, but it is easy to control the light transmittance and the manufacturing cost. It is preferably composed of a single layer from the surface. When the protective film-forming film is composed of a plurality of layers, it is preferable that the plurality of layers as a whole satisfy the above-mentioned light transmittance from the viewpoint of ease of controlling the light transmittance.

2. 2. Material The protective film-forming film is preferably made of an uncured curable adhesive. In this case, by superimposing a work such as a semiconductor wafer on the protective film-forming film and then curing the protective film-forming film, the protective film can be firmly adhered to the work, and a durable protective film can be chipped. Etc. can be formed.

When the protective film-forming film is made of an uncured curable adhesive, the light transmittance of the protective film-forming film hardly changes before or after curing. Therefore, if the light transmittance of the protective film-forming film before curing is 25% or more and the light transmittance at a wavelength of 550 nm is 20% or less, the wavelength of the protective film-forming film (protective film) after curing is 1600 nm. The light transmittance is 25% or more, and the light transmittance at a wavelength of 550 nm is 20% or less.

The protective film-forming film preferably has adhesiveness at room temperature or exhibits adhesiveness by heating. As a result, when a work such as a semiconductor wafer is superposed on the protective film forming film as described above, both can be bonded together. Therefore, positioning can be reliably performed before the protective film-forming film is cured.

The curable adhesive constituting the protective film-forming film having the above-mentioned properties preferably contains a curable component and a binder polymer component. As the curable component, a thermosetting component, an energy ray-curable component, or a mixture thereof can be used, but it is particularly preferable to use a thermosetting component. This is because the protective film-forming film has the above-mentioned light transmittance, which makes it unsuitable for ultraviolet curing, and is preferably thermosetting.

Examples of the thermosetting component include epoxy resin, phenol resin, melamine resin, urea resin, polyester resin, urethane resin, acrylic resin, polyimide resin, benzoxazine resin and the like, and mixtures thereof. Among these, epoxy resins, phenol resins and mixtures thereof are preferably used.

Epoxy resin has the property of forming a three-dimensional network when heated and forming a strong film. As such an epoxy resin, various conventionally known epoxy resins are used, but those having a molecular weight of about 300 to 2000 are usually preferable, and those having a molecular weight of 300 to 500 are particularly preferable. Further, it is preferable to use a blend of a normally liquid epoxy resin having a molecular weight of 330 to 400 and an epoxy resin having a molecular weight of 400 to 2500, particularly a solid epoxy resin at room temperature of 500 to 2000. The epoxy equivalent of the epoxy resin is preferably 50 to 5000 g / eq.

Specific examples of such epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenylnovolac, and cresolnovolac; and glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; Glycidyl ether of carboxylic acids such as phthalic acid, isophthalic acid, tetrahydrophthalic acid; glycidyl-type or alkylglycidyl-type epoxy resin in which active hydrogen bonded to a nitrogen atom such as aniline isocyanurate is replaced with a glycidyl group; vinylcyclohexanediepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, 2- (3,4-epoxy) cyclohexyl-5,5-spiro (3,4-epoxy) cyclohexane-m-dioxane, etc. Examples thereof include so-called alicyclic epoxides in which an epoxy is introduced by oxidizing a carbon-carbon double bond in a molecule. In addition, an epoxy resin having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, or the like can also be used.

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

When an epoxy resin is used, it is preferable to use a thermoactive latent epoxy resin curing agent in combination as an auxiliary agent. The thermoactive latent epoxy resin curing agent is a type of curing agent that does not react with the epoxy resin at room temperature, is activated by heating at a certain temperature or higher, and reacts with the epoxy resin. The method of activating the heat-activated latent epoxy resin curing agent is a method of generating active species (anions, cations) by a chemical reaction by heating; the epoxy resin is stably dispersed in the epoxy resin near room temperature and is at a high temperature. There are methods such as a method of incompatible with and dissolving with and starting a curing reaction; a method of eluting at a high temperature with a molecular sieve-encapsulated type curing agent and starting a curing reaction; a method of using microcapsules and the like.

Specific examples of the thermoactive latent epoxy resin curing agent include various onium salts, refractory active hydrogen compounds such as dibasic acid dihydrazide compounds, dicyandiamides, amine adduct curing agents, and imidazole compounds. These heat-activated latent epoxy resin curing agents may be used alone or in combination of two or more. The heat-active latent epoxy resin curing agent as described above is preferably 0.1 to 20 parts by weight, particularly preferably 0.2 to 10 parts by weight, still more preferably 0. It is used in a proportion of 3 to 5 parts by weight.

As the phenolic resin, a condensate of phenols such as alkylphenol, polyhydric phenol, and naphthol and aldehydes is used without particular limitation. Specifically, phenol novolac resin, o-cresol novolak resin, p-cresol novolak resin, t-butylphenol novolak resin, dicyclopentadiencresol resin, polyparavinylphenol resin, bisphenol A type novolak resin, or modified products thereof. Etc. are used.

The phenolic hydroxyl group contained in these phenolic resins can be easily added and reacted with the epoxy group of the epoxy resin by heating to form a cured product having high impact resistance. Therefore, the epoxy resin and the phenolic resin may be used in combination.

The binder polymer component can give an appropriate tack to the protective film-forming film and improve the operability of the protective film-forming composite sheet 3. The weight average molecular weight of the binder polymer is usually in the range of 50,000 to 2 million, preferably 100,000 to 1,500,000, particularly preferably 200,000 to 1,000,000. If the molecular weight is too low, the film formation of the protective film-forming film is insufficient, and if it is too high, the compatibility with other components is deteriorated, and as a result, uniform film formation is hindered. As such a binder polymer, for example, an acrylic polymer, a polyester resin, a phenoxy resin, a urethane resin, a silicone resin, a rubber polymer and the like are used, and an acrylic polymer is particularly preferably used.

Examples of the acrylic polymer include a (meth) acrylic acid ester copolymer composed of a (meth) acrylic acid ester monomer and a structural unit derived from a (meth) acrylic acid derivative. Here, as the (meth) acrylic acid ester monomer, a (meth) acrylic acid alkyl ester preferably having an alkyl group having 1 to 18 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth). ) Propyl acrylate, butyl (meth) acrylate and the like are used. Examples of the (meth) acrylic acid derivative include (meth) acrylic acid, glycidyl (meth) acrylic acid, and hydroxyethyl (meth) acrylate.

Among the above, when a glycidyl group is introduced into an acrylic polymer using glycidyl methacrylate or the like as a constituent unit, the compatibility with the epoxy resin as the thermosetting component described above is improved, and the glass after curing of the protective film-forming film is improved. The transition temperature (Tg) becomes high and the heat resistance is improved. Further, among the above, when a hydroxyl group is introduced into an acrylic polymer using hydroxyethyl acrylate or the like as a constituent unit, the adhesion to the work and the adhesive physical characteristics can be controlled.

When an acrylic polymer is used as the binder polymer, the weight average molecular weight of the polymer is preferably 100,000 or more, and particularly preferably 150,000 to 1,000,000. The glass transition temperature of the acrylic polymer is usually 20 ° C. or lower, preferably about −70 to 0 ° C., and has adhesiveness at room temperature (23 ° C.).

The mixing ratio of the thermosetting component and the binder polymer component is such that the thermosetting component is preferably 50 to 1500 parts by weight, particularly preferably 70 to 1000 parts by weight, more preferably 70 parts by weight, based on 100 parts by weight of the binder polymer component. It is preferable to blend 80 to 800 parts by weight. When the thermosetting component and the binder polymer component are mixed in such a ratio, an appropriate tack is exhibited before curing, the sticking work can be performed stably, and after curing, protection having excellent film strength is achieved. A membrane is obtained.

The protective film-forming film preferably contains a colorant and / or a filler, and particularly preferably contains both a colorant and a filler. This makes it possible to control the light transmittance at a wavelength of 1600 nm and a wavelength of 550 nm within the above-mentioned range. Further, when the protective film-forming film contains a filler, the hardness of the protective film after curing can be maintained high, and the moisture resistance can be improved. Further, the coefficient of thermal expansion of the protective film after curing can be brought close to the coefficient of thermal expansion of the semiconductor wafer, whereby the warp of the semiconductor wafer during processing can be reduced.

As the colorant, for example, known ones such as inorganic pigments, organic pigments, and organic dyes can be used, but from the viewpoint of controllability of light transmittance, it is preferable to use inorganic pigments.

Examples of inorganic pigments include carbon black, cobalt pigments, iron pigments, chromium pigments, titanium pigments, vanadium pigments, zirconium pigments, molybdenum pigments, ruthenium pigments, platinum pigments, and ITO (indium). Examples thereof include tin oxide) dyes and ATO (antimons tin oxide) dyes.

Examples of organic pigments and organic dyes include aminium pigments, cyanine pigments, merocyanine pigments, croconium pigments, squalium pigments, azulenium pigments, polymethine pigments, naphthoquinone pigments, pyrylium pigments, and phthalocyanine pigments. Dyes, naphthalocyanine pigments, naphtholactam pigments, azo pigments, condensed azo pigments, indigo pigments, perinone pigments, perylene pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, quinophthalone pigments, Pyrrole pigments, thioindigo pigments, metal complex pigments (metal complex salt dyes), dithiol metal complex pigments, indolphenol pigments, triallylmethane pigments, anthraquinone pigments, dioxazine pigments, naphthol pigments, azomethine pigments. , Benzimidazolone pigments, pyranthron pigments, slene pigments and the like. These pigments or dyes can be appropriately mixed and used in order to adjust the desired light transmittance.

Among the above, it is particularly preferable to use carbon black. According to carbon black, it is easy to control the light transmittance at a wavelength of 1600 nm and a wavelength of 550 nm within the above-mentioned range.

The amount of the colorant (particularly carbon black) blended in the protective film-forming film varies depending on the thickness of the protective film-forming film, but for example, when the thickness of the protective film-forming film is 25 μm, the mass is 0.05 to 1 mass. %, Especially preferably 0.075 to 0.75% by mass, and more preferably 0.1 to 0.5% by mass. When the blending amount of the colorant is 0.05% by mass or more, it is easy to control the light transmittance at a wavelength of 550 nm to 20% or less so that the grinding marks on the semiconductor chip or the like cannot be visually seen. On the other hand, if the blending amount of the colorant exceeds 1% by mass, infrared rays do not pass through the protective film forming film (protective film), and infrared inspection may not be possible. When the thickness of the protective film-forming film is thin, the light transmittance tends to be high, and when the thickness of the protective film-forming film is thick, the light transmittance tends to be low. It is desirable to appropriately adjust the blending amount of the colorant according to the thickness. Specifically, it is desirable to adjust the thickness of the protective film-forming film and the amount of the colorant to be blended in an inversely proportional relationship.

The average particle size of the colorant (particularly carbon black) is preferably 1 to 500 nm, particularly preferably 3 to 100 nm, and further preferably 5 to 50 nm. When the average particle size of the colorant is within the above range, it is easy to control the light transmittance at a wavelength of 550 nm and the light transmittance at a wavelength of 1600 nm within the above range. The average particle size of the colorant in the present specification is a value measured by a dynamic light scattering method using a particle size distribution measuring device (Nanotrack Wave-UT151, manufactured by Nikkiso Co., Ltd.).

Examples of the filler include silica such as crystalline silica, molten silica and synthetic silica, and inorganic fillers such as alumina and glass balloon. Of these, silica is preferable, synthetic silica is more preferable, and synthetic silica of a type in which the source of α rays, which causes malfunction of the semiconductor device, is removed as much as possible is the most suitable. Examples of the shape of the filler include a spherical shape, a needle shape, an amorphous shape, and the like, and the filler shape is preferably spherical, and particularly preferably true spherical. When the filler is spherical or true spherical, diffused reflection of light rays is unlikely to occur, and the above-mentioned infrared inspection can be performed satisfactorily.

Further, as the filler added to the protective film forming film, a functional filler may be blended in addition to the above-mentioned inorganic filler. Examples of the functional filler include gold, silver, copper, nickel, aluminum, stainless steel, carbon, ceramic, nickel, aluminum, and the like coated with silver for the purpose of imparting conductivity after die bonding. Examples thereof include metal materials such as gold, silver, copper, nickel, aluminum, stainless steel, silicon and germanium for the purpose of imparting thermal conductivity, and thermal conductive fillers such as alloys thereof.

The average particle size of the filler (particularly the silica filler) is preferably 0.01 to 10 μm, more preferably 0.01 to 3 μm, particularly preferably 0.03 to 2 μm, and further 0. It is preferably .05 to 1 μm. When the average particle size of the filler is 0.01 μm or more, it is easy to control the light transmittance at a wavelength of 550 nm to 20% or less so that grinding marks on a semiconductor chip or the like cannot be visually seen. On the other hand, if the average particle size of the filler exceeds 10 μm, the surface condition of the protective film-forming film may deteriorate. Further, if the average particle size of the filler exceeds 3 μm, it may be difficult to perform an infrared inspection due to diffuse reflection of infrared rays. The average particle size of the filler less than 1 μm in the present specification is a value measured by a dynamic light scattering method using a particle size distribution measuring device (Nanotrack Wave-UT151, manufactured by Nikkiso Co., Ltd.). The average particle size of the filler of 1 μm or more is a value measured by a laser diffraction / scattering method using a particle size distribution measuring device (Nikkiso Co., Ltd., Microtrac MT3000II).

The blending amount of the filler (particularly silica filler) in the protective film forming film is preferably 10 to 80% by mass, particularly preferably 20 to 70% by mass, and further preferably 30 to 65% by mass. Is preferable. When the blending amount of the filler is 10% by mass or more, it is easy to control the light transmittance at a wavelength of 550 nm to 20% or less so that the grinding marks on the semiconductor chip or the like cannot be visually seen. On the other hand, if the blending amount of the filler exceeds 80% by mass, infrared rays do not pass through the protective film forming film (protective film), and infrared inspection may not be possible.

The protective film-forming film may contain a coupling agent. By containing the coupling agent, after the protective film forming film is cured, the adhesiveness and adhesion between the protective film and the work can be improved without impairing the heat resistance of the protective film, and water resistance (water resistance ( Moisture and heat resistance) can be improved. As the coupling agent, a silane coupling agent is preferable because of its versatility and cost merit.

Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ- (methacryloxy). Propyl) trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-6- (aminoethyl) -γ-aminopropylmethyldiethoxysilane, N -Phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis (3-triethoxysilylpropyl) tetrasulfan, methyltri Examples thereof include methoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazolesilane. These can be used alone or in admixture of two or more.

The protective film-forming film may contain a cross-linking agent such as an organic polyvalent isocyanate compound, an organic polyvalent imine compound, and an organometallic chelate compound in order to adjust the cohesive force before curing. Further, the protective film-forming film may contain an antistatic agent in order to suppress static electricity and improve the reliability of the chip. Further, the protective film-forming film may contain a flame retardant such as a phosphoric acid compound, a brom compound, or a phosphorus compound in order to enhance the flame retardant performance of the protective film and improve the reliability as a package.

The thickness of the protective film-forming film is preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and further 7 to 100 μm in order to effectively exert the function as a protective film. Is preferable.

[Sheet for forming protective film]
FIG. 1 is a cross-sectional view of a protective film forming sheet according to an embodiment of the present invention. As shown in FIG. 1, the protective film forming sheet 2 according to the present embodiment is peeled off by being laminated on one surface (lower surface in FIG. 1) of the protective film forming film 1 and the protective film forming film 1. It is configured to include a sheet 21. However, the release sheet 21 is peeled off when the protective film forming sheet 2 is used.

The release sheet 21 protects the protective film-forming film 1 until the protective film-forming sheet 2 is used, and is not necessarily required. The structure of the release sheet 21 is arbitrary, and examples thereof include a plastic film in which the film itself has peelability with respect to the protective film-forming film 1, and a plastic film peeled with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, a silicone type, a fluorine type, a long chain alkyl type or the like can be used, but among these, a silicone type that can obtain stable performance at low cost is preferable. The thickness of the release sheet 21 is not particularly limited, but is usually about 20 to 250 μm.

The release sheet 21 as described above may also be laminated on the other surface (upper surface in FIG. 1) of the protective film forming film 1. In this case, it is preferable to increase the peeling force of one of the release sheets 21 to obtain a heavy release type release sheet, and decrease the release force of the other release sheet 21 to obtain a light release type release sheet.

In order to manufacture the protective film forming sheet 2 according to the present embodiment, the peeling surface of the release sheet 21 (the surface having peelability; usually the surface that has been peeled, but is not limited to this). Protective film forming film 1 is formed. Specifically, a coating agent for a protective film-forming film containing a curable adhesive constituting the protective film-forming film 1 and, if desired, a solvent is prepared, and a roll coater, a knife coater, a roll knife coater, and an air knife are prepared. A protective film-forming film 1 is formed by applying it to the peeling surface of the release sheet 21 with a coating machine such as a coater, a die coater, a bar coater, a gravure coater, or a curtain coater and drying it.

A method of manufacturing a chip with a protective film from a semiconductor wafer as a work as an example using the protective film forming sheet 2 according to the present embodiment will be described below. First, the protective film-forming film 1 of the protective film-forming sheet 2 is attached to the back surface of the semiconductor wafer in which a circuit is formed on the front surface and back-grinded. At this time, if desired, the protective film-forming film 1 may be heated to exhibit adhesiveness.

Next, the release sheet 21 is peeled from the protective film forming film 1. Then, the protective film forming film 1 is cured to form a protective film to obtain a semiconductor wafer with a protective film. When the protective film-forming film 1 is a thermosetting adhesive, the protective film-forming film 1 may be heated at a predetermined temperature for an appropriate time. The protective film-forming film 1 may be cured after the dicing step.

When the semiconductor wafer with the protective film is obtained as described above, if desired, the protective film is irradiated with laser light to perform laser printing. This laser printing may be performed before the protective film forming film 1 is cured.

Then, using a desired dicing sheet, the semiconductor wafer with a protective film is diced according to a conventional method to obtain a chip having a protective film (chip with a protective film). After that, if desired, the dicing sheet is expanded in the plane direction, and the chip with the protective film is picked up from the dicing sheet.

The chip with a protective film obtained as described above is excellent in appearance because the grinding marks due to the back grind processing are hidden by the protective film and cannot be visually seen. Further, since the chip with the protective film and the semiconductor wafer with the protective film can be inspected by infrared rays through the protective film, cracks and the like can be found by the infrared inspection, and the product yield can be improved.

Infrared inspection is an inspection performed using infrared rays, and by acquiring infrared rays from a workpiece with a protective film such as a semiconductor wafer with a protective film or a workpiece such as a chip with a protective film through the protective film. It can be carried out. The wavelength of the infrared rays to be acquired is usually 800 to 2800 nm, preferably 1100 to 2100 nm. As the device for infrared inspection, a known device, for example, a device having an infrared camera, an infrared microscope, or the like can be used.

[Composite sheet for forming protective film]
FIG. 2 is a cross-sectional view of a composite sheet for forming a protective film according to an embodiment of the present invention. As shown in FIG. 2, the protective film forming composite sheet 3 according to the present embodiment has a pressure-sensitive adhesive sheet 4 in which a pressure-sensitive adhesive layer 42 is laminated on one surface of a base material 41 and a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet 4. The protective film-forming film 1 laminated on the 42 side and the jig adhesive layer 5 laminated on the peripheral edge of the protective film-forming film 1 on the opposite side of the pressure-sensitive adhesive sheet 4 are provided. The jig adhesive layer 5 is a layer for adhering the protective film forming composite sheet 3 to a jig such as a ring frame.

The composite sheet 3 for forming a protective film according to the embodiment is attached to the work to hold the work when the work is processed, and the protective film is applied to the work or a work piece obtained by processing the work. Used to form. This protective film is composed of a protective film-forming film 1, preferably a cured protective film-forming film 1.

The composite sheet 3 for forming a protective film according to the embodiment is used, for example, for holding a semiconductor wafer during dicing processing of a semiconductor wafer as a work and for forming a protective film on a semiconductor chip obtained by dicing. It is not limited to this. The adhesive sheet 4 of the protective film forming composite sheet 3 in this case is usually referred to as a dicing sheet.

1. 1. Adhesive Sheet The adhesive sheet 4 of the protective film forming composite sheet 3 according to the present embodiment includes a base material 41 and a pressure-sensitive adhesive layer 42 laminated on one surface of the base material 41.

1-1. Base material The base material 41 of the pressure-sensitive adhesive sheet 4 is not particularly limited as long as it is suitable for processing a work, for example, dicing and expanding a semiconductor wafer, and usually uses a resin-based material as a main material. It is composed of a film (hereinafter referred to as "resin film").

Specific examples of the resin film include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film, polypropylene film, polybutene film, polybutadiene film, and polymethylpentene film. , Ethethylene-norbornene copolymer film, polyolefin-based film such as norbornene resin film; ethylene-vinyl acetate copolymer film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer Ethylene-based copolymer films such as films; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; polyester-based films such as polyethylene terephthalate films and polybutylene terephthalate films; polyurethane films; polyimide films; polystyrene films ; Polycarbonate film; Fluororesin film and the like. Further, modified films such as these crosslinked films and ionomer films are also used. The base material 41 may be a film composed of one of these types, or may be a laminated film in which two or more types of these are combined. In addition, "(meth) acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

Among the above, a polyolefin film is preferable from the viewpoint of environmental safety, cost and the like, and among them, a polypropylene film having excellent heat resistance is preferable. If it is a polypropylene film, heat resistance can be imparted to the base material 41 without impairing the expandability of the pressure-sensitive adhesive sheet 4 and the pick-up suitability of the chips. Since the base material 41 has such heat resistance, even when the protective film forming film 1 is thermoset while the protective film forming composite sheet 3 is attached to the work, the occurrence of slackening of the adhesive sheet 4 is suppressed. be able to.

For the purpose of improving the adhesion to the pressure-sensitive adhesive layer 42 laminated on the surface of the resin film, one or both sides thereof may be subjected to surface treatment or primer treatment by an oxidation method, an unevenness method or the like, if desired. it can. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment, and examples of the unevenness method include sandblasting and sandblasting. Examples include a thermal spraying method.

The base material 41 may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler in the resin film.

The thickness of the base material 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 breaking elongation of the base material 41 of the pressure-sensitive adhesive sheet 4 in the present embodiment is preferably 100% or more, particularly preferably 200 to 1000%, as a value measured at 23 ° C. and 50% relative humidity. .. Here, the elongation at break is the elongation rate of the length of the test piece at the time of breaking the test piece with respect to the original length in the tensile test according to JIS K7161: 1994 (ISO 527-1 1993). The base material 41 having a breaking elongation of 100% or more is hard to break during the expanding step, and the chips formed by cutting the work can be easily separated.

Further, the tensile stress at 25% strain of the base material 41 of the pressure-sensitive adhesive sheet 4 in the present embodiment is preferably 5 to 15 N / 10 mm, and the maximum tensile stress is preferably 15 to 50 MPa. Here, the tensile stress at 25% strain and the maximum tensile stress are measured by a test according to JIS K7161: 1994. When the tensile stress at 25% strain is 5 N / 10 mm or more and the maximum tensile stress is 15 MPa or more, the base material 2 will loosen when the work is attached to the dicing sheet 1 and then fixed to a frame such as a ring frame. It is possible to suppress the occurrence and prevent a transfer error from occurring. On the other hand, when the tensile stress at 25% strain is 15 N / 10 mm or less and the maximum tensile stress is 50 MPa or less, the dicing sheet 1 itself is suppressed from peeling from the ring frame during the expanding step. The above-mentioned breaking elongation, tensile stress at 25% strain, and maximum tensile stress refer to the values measured in the long direction of the original fabric of the base material 41.

1-2. Adhesive layer The pressure-sensitive adhesive layer 42 included in the pressure-sensitive adhesive sheet 4 of the protective film-forming composite sheet 3 according to the present embodiment may be composed of a non-energy ray-curable pressure-sensitive adhesive or may be composed of an energy ray-curable pressure-sensitive adhesive. May be done. The non-energy ray-curable pressure-sensitive adhesive preferably has desired adhesive strength and removability. For example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a polyester-based pressure-sensitive adhesive. , Polyvinyl ether adhesives and the like can be used. Among these, an acrylic pressure-sensitive adhesive that has high adhesion to the protective film-forming film 1 and can effectively suppress the work or processed material from falling off in a dicing step or the like is preferable.

On the other hand, since the adhesive strength of the energy ray-curable adhesive is reduced by the energy ray irradiation, when it is desired to separate the work or the work piece and the adhesive sheet 4, the energy ray-curable adhesive can be easily separated by the energy ray irradiation. it can.

When the pressure-sensitive adhesive layer 42 is made of an energy ray-curable pressure-sensitive adhesive, it is preferable that the pressure-sensitive adhesive layer 42 in the protective film-forming composite sheet 3 is cured. A material obtained by curing an energy ray-curable pressure-sensitive adhesive usually has a high elastic modulus and a high surface smoothness. Therefore, the protective film forming film 3 in contact with the cured portion made of such a material is cured to form a protective film. When the film is formed, the surface of the protective film in contact with the cured portion has high smoothness (gloss), which makes it aesthetically pleasing as a protective film for the chip. Further, when laser printing is applied to a protective film having high surface smoothness, the visibility of the printing is improved.

The energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 42 may be mainly composed of a polymer having energy ray-curability, or may be a polymer having no energy ray-curability and many energy ray-curable adhesives. The main component may be a mixture of a functional monomer and / or an oligomer.

The case where the energy ray-curable pressure-sensitive adhesive contains a polymer having energy ray-curability as a main component will be described below.

The energy ray-curable polymer is a (meth) acrylic acid ester (co) polymer (A) in which a functional group (energy ray-curable group) having energy ray curability is introduced into a side chain (hereinafter, "energy ray curable"). It may be referred to as "curable polymer (A)"). This energy ray-curable polymer (A) is a (meth) acrylic copolymer (a1) having a functional group-containing monomer unit and an unsaturated group-containing compound (a2) having a substituent bonded to the functional group. It is preferable that it is obtained by reacting with.

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

The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) is a monomer 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. Is preferable.

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

The (meth) acrylic acid ester monomer constituting the acrylic copolymer (a1) includes alkyl (meth) acrylate, cycloalkyl (meth) acrylate, and benzyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. Is used. Among these, alkyl (meth) acrylates in which the alkyl group has 1 to 18 carbon atoms are particularly preferably methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth) acrylate. , 2-Ethylhexyl (meth) acrylate and the like are used.

The acrylic copolymer (a1) contains a structural unit derived from the functional group-containing monomer in a proportion of usually 3 to 100% by mass, preferably 5 to 40% by mass, and is a (meth) acrylic acid ester monomer or a component thereof. The structural unit derived from the derivative is usually contained in an amount of 0 to 97% by mass, preferably 60 to 95% by mass.

The acrylic copolymer (a1) can be obtained by copolymerizing a functional group-containing monomer as described above with a (meth) acrylic acid ester monomer or a derivative thereof by a conventional method, but in addition to these monomers, Dimethylacrylamide, vinyl formate, vinyl acetate, styrene and the like may be copolymerized.

By reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with the unsaturated group-containing compound (a2) having a substituent bonded to the functional group, the energy ray-curable polymer (A) ) Is obtained.

The substituent contained in the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit contained in 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, and when the functional group is an epoxy group, the substituent is an amino group, a carboxyl group or an aziridinyl group. preferable.

The unsaturated group-containing compound (a2) contains 1 to 5 energy ray-polymerizable carbon-carbon double bonds, preferably 1 to 2 per molecule. Specific examples of such an unsaturated group-containing compound (a2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1-(. Bisacryloyloxymethyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, hydroxyethyl (meth) Acryloyl monoisocyanate compound obtained by reaction with acrylate; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl- 2-Oxazoline and the like can be mentioned.

The unsaturated group-containing compound (a2) is usually used at a ratio of usually 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 temperature, pressure, solvent, time, presence / absence of catalyst, and catalyst of the reaction depend on the combination of the functional group and the substituent. The type of can be appropriately selected. As a result, the functional group present in the acrylic copolymer (a1) reacts with the substituent in the unsaturated group-containing compound (a2), and the unsaturated group is contained in the acrylic copolymer (a1). It is introduced into the side chain to obtain an energy ray-curable polymer (A).

The weight average molecular weight of the energy ray-curable polymer (A) thus obtained is preferably 10,000 or more, particularly preferably 150,000 to 1.5 million, and further 200,000 to 1,000,000. Is preferable. The weight average molecular weight (Mw) in the present specification is a polystyrene-equivalent value measured by a gel permeation chromatography method (GPC method).

Even when the energy ray-curable pressure-sensitive adhesive is mainly composed of an energy ray-curable polymer, the energy ray-curable pressure-sensitive adhesive further contains an energy ray-curable monomer and / or an oligomer (B). You may.

As the energy ray-curable monomer and / or oligomer (B), for example, an ester of a polyhydric alcohol and (meth) acrylic acid can be used.

Examples of the energy ray-curable monomer and / or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, trimethyl propantri (meth) acrylate, and penta. Elythritol 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 Examples thereof include polyfunctional acrylic acid esters such as di (meth) acrylate and dimethylol tricyclodecanedi (meth) acrylate, polyester oligo (meth) acrylate, and polyurethane oligo (meth) acrylate.

When the energy ray-curable monomer and / or oligomer (B) is blended, the content of the energy ray-curable monomer and / or oligomer (B) in the energy ray-curable pressure-sensitive adhesive is 5 to 80% by mass. It is preferably abundant, and particularly preferably 20 to 60% by mass.

Here, when ultraviolet rays are used as the energy rays for curing the energy ray-curable resin composition, it is preferable to add a photopolymerization initiator (C), and by using this photopolymerization initiator (C). , The polymerization curing time and the amount of light irradiation can be reduced.

Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, and benzoin dimethyl ketal. 2,4-Diethylthioxanthone, 1-hydroxycyclohexylphenylketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4) 6-trimethylbenzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate, oligo {2-hydroxy-2-methyl-1- [4- (1-propenyl) phenyl] propanone}, 2, Examples thereof include 2-dimethoxy-1,2-diphenylethane-1-one. These may be used alone or in combination of two or more.

The photopolymerization initiator (C) is an energy ray-curable copolymer (A) (when an energy ray-curable monomer and / or an oligomer (B) is blended, the energy ray-curable copolymer (A)). And energy ray-curable monomer and / or oligomer (B) total amount 100 parts by mass) 0.1 to 10 parts by mass, especially in the range of 0.5 to 6 parts by mass with respect to 100 parts by mass. It is preferable to be

In the energy ray-curable pressure-sensitive adhesive, other components may be appropriately added in addition to the above components. Examples of other components include a polymer component or an oligomer component (D) having no energy ray curability, a cross-linking agent (E), and the like.

Examples of the polymer component or oligomer component (D) having no energy ray curability include polyacrylic acid ester, polyester, polyurethane, polycarbonate, and polyolefin, and a polymer having a weight average molecular weight (Mw) of 3000 to 2.5 million. Alternatively, an oligomer is preferable.

As the cross-linking agent (E), a polyfunctional compound having reactivity with a functional group of the energy ray-curable copolymer (A) or the like can be used. Examples of such polyfunctional compounds include isocyanato compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts and ammonium salts. , Reactive phenolic resin and the like.

By blending these other components (D) and (E) with the energy ray-curable pressure-sensitive adhesive, the adhesiveness and peelability before curing, the strength after curing, the adhesiveness with other layers, the storage stability, etc. Can be improved. The blending amount of these other components is not particularly limited, and is appropriately determined in the range of 0 to 40 parts by mass with respect to 100 parts by mass of the energy ray-curable copolymer (A).

Next, a case where the energy ray-curable pressure-sensitive adhesive contains a mixture of a polymer component having no energy ray-curability and an energy ray-curable polyfunctional monomer and / or oligomer as a main component will be described below.

As the polymer component having no energy ray curability, for example, the same component as the acrylic copolymer (a1) described above can be used. The content of the polymer component having no energy ray curability in the energy ray curable resin composition is preferably 20 to 99.9% by mass, and particularly preferably 30 to 80% by mass.

As the energy ray-curable polyfunctional monomer and / or oligomer, the same component (B) as described above is selected. The blending ratio of the polymer component having no energy ray curability and the energy ray curable polyfunctional monomer and / or oligomer is 10 to 150 parts by mass of the polyfunctional monomer and / or oligomer with respect to 100 parts by mass of the polymer component. It is preferably present, and particularly preferably 25 to 100 parts by mass.

In this case as well, the photopolymerization initiator (C) and the cross-linking agent (E) can be appropriately blended in the same manner as described above.

The thickness of the pressure-sensitive 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 further preferably 3 to 20 μm.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 5 for jigs preferably has desired adhesive strength and removability, and is, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or a urethane-based pressure-sensitive adhesive. , Polyester-based adhesives, polyvinyl ether-based adhesives and the like can be used. Among these, an acrylic adhesive that has high adhesion to a jig such as a ring frame and can effectively prevent the composite sheet 3 for forming a protective film from peeling off from the ring frame or the like in a dicing process or the like. preferable. A base material as a core material may be interposed in the middle of the adhesive layer 5 for jigs in the thickness direction.

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

2. 2. Method for Producing Protective Film-Forming Composite Sheet The protective film-forming composite sheet 3 preferably separately produces a first laminate containing the protective film-forming film 1 and a second laminate containing the adhesive sheet 4. After that, it can be produced by laminating the protective film forming film 1 and the pressure-sensitive adhesive sheet 4 using the first laminated body and the second laminated body, but the present invention is not limited thereto.

In order to produce the first laminated body, the protective film forming film 1 is formed on the peeling surface of the first peeling sheet. Specifically, a coating agent for a protective film-forming film containing a curable adhesive constituting the protective film-forming film 1 and, if desired, a solvent is prepared, and a roll coater, a knife coater, a roll knife coater, and an air knife are prepared. A protective film-forming film 1 is formed by applying a coating machine such as a coater, a die coater, a bar coater, a gravure coater, and a curtain coater to the peeling surface of the first release sheet and drying it. Next, the peeling surface of the second release sheet is overlapped with the exposed surface of the protective film forming film 1 and pressure-bonded, and the protective film forming film 1 is sandwiched between the two release sheets (first laminated body). ).

In this first laminated body, a half cut may be made if desired, and the protective film forming film 1 (and the second release sheet) may have a desired shape, for example, a circular shape. In this case, the excess portions of the protective film forming film 1 and the second release sheet generated by the half cut may be appropriately removed.

On the other hand, in order to produce the second laminate, a coating agent for the pressure-sensitive adhesive layer containing a pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 42 and, if desired, a solvent is applied to the peel-off surface of the third release sheet. It is applied and dried to form the pressure-sensitive adhesive layer 42. After that, the base material 41 is pressure-bonded to the exposed surface of the pressure-sensitive adhesive layer 42, and a laminate (second laminate) composed of the pressure-sensitive adhesive sheet 4 composed of the base material 41 and the pressure-sensitive adhesive layer 42 and the third release sheet is formed. obtain.

Here, when the pressure-sensitive adhesive layer 42 is made of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer 42 may be irradiated with energy rays at this stage to cure the pressure-sensitive adhesive layer 42 or protect it. The pressure-sensitive adhesive layer 42 may be cured after being laminated with the film-forming film 1. When the pressure-sensitive adhesive layer 42 is cured after being laminated with the protective film-forming film 1, the pressure-sensitive adhesive layer 42 may be cured before the dicing step, or the pressure-sensitive adhesive layer 42 may be cured after the dicing step.

As the energy ray, ultraviolet rays, electron beams and the like are usually used. The irradiation amount of energy rays varies depending on the type of energy rays, but in the case of ultraviolet rays, for example, the amount of light is preferably 50 to 1000 mJ / cm2, and particularly preferably 100 to 500 mJ / cm2. Further, in the case of an electron beam, about 10 to 1000 grad is preferable.

When the first laminated body and the second laminated body are obtained as described above, the second release sheet in the first laminated body is peeled off, and the third release sheet in the second laminated body is peeled off. Then, the protective film-forming film 1 exposed in the first laminate and the adhesive layer 42 of the adhesive sheet 4 exposed in the second laminate are overlapped and pressure-bonded. The pressure-sensitive adhesive sheet 4 may be half-cut if desired, and may have a desired shape, for example, a circular shape having a diameter larger than that of the protective film-forming film 1. In this case, the excess portion of the pressure-sensitive adhesive sheet 4 generated by the half-cut may be appropriately removed.

In this way, the pressure-sensitive adhesive sheet 4 in which the pressure-sensitive adhesive layer 42 is laminated on the base material 41, the protective film-forming film 1 laminated on the pressure-sensitive adhesive layer 42 side of the pressure-sensitive adhesive sheet 4, and the protective film-forming film 1 A composite sheet 3 for forming a protective film is obtained, which is composed of a first release sheet laminated on the side opposite to the adhesive sheet 4 in the above. Finally, after the first release sheet is peeled off, the adhesive layer 5 for jigs is formed on the peripheral edge of the protective film forming film 1 opposite to the pressure-sensitive adhesive sheet 4. The adhesive layer 5 for jigs can also be applied and formed by the same method as the adhesive layer 42.

3. 3. Method of Using Protective Film-Forming Composite Sheet A method of manufacturing a chip with a protective film from a semiconductor wafer as a work by using the protective film-forming composite sheet 3 according to the present embodiment will be described below.

As shown in FIG. 4, the protective film forming film 1 is attached to the semiconductor wafer 6, and the adhesive layer 5 for jigs is attached to the ring frame 7. When the protective film-forming film 1 is attached to the semiconductor wafer 6, the protective film-forming film 1 may be heated to exhibit adhesiveness, if desired.

Then, the protective film forming film 1 is cured to form a protective film, and a semiconductor wafer 6 with a protective film is obtained. When the protective film-forming film 1 is a thermosetting adhesive, the protective film-forming film 1 may be heated at a predetermined temperature for an appropriate time. The protective film-forming film 1 may be cured after the dicing step.

When the semiconductor wafer 6 with a protective film is obtained as described above, if desired, the protective film is irradiated with laser light via the adhesive sheet 4 to perform laser printing. This laser printing may be performed before the protective film forming film 1 is cured.

Next, the semiconductor wafer 6 with a protective film is diced according to a conventional method to obtain a chip having a protective film (chip with a protective film). After that, if desired, the pressure-sensitive adhesive sheet 4 is expanded in the plane direction, and the chip with the protective film is picked up from the pressure-sensitive adhesive sheet 4.

The chip with a protective film obtained as described above is excellent in appearance because the grinding marks due to the back grind processing are hidden by the protective film and cannot be visually seen. Further, since the chip with the protective film and the semiconductor wafer with the protective film can be inspected by infrared rays through the protective film, cracks and the like can be found by the infrared inspection, and the product yield can be improved.

4. Other Embodiments of Protective Film Forming Composite Sheet FIG. 3 is a cross-sectional view of the protective film forming composite sheet according to another embodiment of the present invention. As shown in FIG. 3, the protective film forming composite sheet 3A according to the present embodiment includes a pressure-sensitive adhesive sheet 4 in which a pressure-sensitive adhesive layer 42 is laminated on one surface of a base material 41 and a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet 4. It is configured to include a protective film forming film 1 laminated on the 42 side. The protective film-forming film 1 in the embodiment is formed to be substantially the same as the work in the surface direction or slightly larger than the work, and is formed smaller in the surface direction than the adhesive sheet 4. The adhesive layer 42 in the portion where the protective film forming film 1 is not laminated can be attached to a jig such as a ring frame.

The material and thickness of each member of the protective film forming composite sheet 3A according to the present embodiment are the same as the material and thickness of each member of the protective film forming composite sheet 3 described above. However, when the pressure-sensitive adhesive layer 42 is made of an energy ray-curable pressure-sensitive adhesive, the portion of the pressure-sensitive adhesive layer 42 that comes into contact with the protective film-forming adhesive cures the energy ray-curable pressure-sensitive adhesive, and the other portion is energy. It is preferable not to cure the linear curable adhesive. As a result, the smoothness (gloss) of the protective film obtained by curing the protective film forming film 1 can be increased, and the adhesive force to a jig such as a ring frame can be maintained high.

In addition, on the peripheral edge of the pressure-sensitive adhesive layer 42 of the pressure-sensitive adhesive sheet 4 of the protective film-forming composite sheet 3A on the opposite side of the base material 41, the above-mentioned adhesive layer 5 for jigs of the protective film-forming composite sheet 3 is formed. A similar adhesive layer for jigs may be provided separately.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, a release sheet may be laminated on the side of the protective film forming film 1 of the protective film forming composite sheets 3 and 3A opposite to the pressure-sensitive adhesive sheet 4.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
Each of the following components was mixed at the blending ratio (in terms of solid content) shown in Table 1 and diluted with methyl ethyl ketone so that the solid content concentration was 61% by mass to prepare a coating agent for a protective film-forming film.
(A) Binder polymer: A (meth) acrylic acid ester copolymer obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate and 15 parts by mass of 2-hydroxyethyl acrylate. Weight average molecular weight: 800,000, glass transition temperature: -1 ° C)
(B-1) Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184 to 194 g / eq)
(B-2) Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER1055, epoxy equivalent 800-900 g / eq)
(B-3) Dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., Epicron HP-7200HH, epoxy equivalent 255-260 g / eq)
(C) Thermally active latent epoxy resin curing agent: dicyandiamide (manufactured by ADEKA, ADEKA HANDNER EH-3636AS, active hydrogen amount 21 g / eq)
(D) Curing accelerator: 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Corporation, Curesol 2PHZ)
(E-1) Silica filler (manufactured by Admatex, SC2050MA, average particle size 0.5 μm)
(E-2) Silica filler (manufactured by Tokuyama Corporation, UF310, average particle size 3 μm)
(E-3) Silica filler (manufactured by Tatsumori, SV-10, average particle size 8 μm)
(F) Colorant: Carbon black (manufactured by Mitsubishi Chemical Corporation, # MA650, average particle size 28 nm)
(G) Silane coupling agent (manufactured by Nippon Unicar Co., Ltd., A-1110)

A first release sheet (Lintec Corporation: SP-PET3811, thickness 38 μm) in which a silicone-based release agent layer is formed on one side of a polyethylene terephthalate (PET) film, and a silicone-based release agent on one side of the PET film. A second release sheet (manufactured by Lintec Corporation: SP-PET381031, thickness 38 μm) on which a layer was formed was prepared.

The above-mentioned coating agent for a protective film-forming film is applied onto the peeling surface of the first release sheet with a knife coater so that the thickness of the finally obtained protective film-forming film is 25 μm, and then the oven. The film was dried at 120 ° C. for 2 minutes to form a protective film-forming film. Next, the release surface of the second release sheet is overlapped with the protective film-forming film and the two are bonded to each other, and the first release sheet (release sheet 21 in FIG. 1) and the protective film-forming film (protection film-forming film in FIG. 1) are laminated. 1) (Thickness: 25 μm) and a second release sheet for forming a protective film were obtained.

[Examples 2 to 4, Comparative Examples 1 to 4]
A protective film-forming sheet was produced in the same manner as in Example 1 except that the types and blending amounts of the components constituting the protective film-forming film were changed as shown in Table 1.

[Test Example 1] <Measurement of light transmittance>
The second release sheet is peeled off from the protective film-forming sheet obtained in Examples and Comparative Examples, heated in an oven at 130 ° C. for 2 hours in an air atmosphere, and the protective film-forming film is thermoset to protect it. It was made into a film. Then, the first release sheet was peeled off.

Using a spectrophotometer (UV-VIS-NIR SPECTROPHOTOMETER UV-3600, manufactured by SHIMADZU), the transmittance of the protective film was measured, and the transmittance (%) of wavelengths of 550 nm (visible light) and 1600 nm (infrared rays) was measured. ) Was extracted. For the measurement, the attached large sample chamber MPC-3100 was used, and the measurement was performed without using the built-in integrating sphere. The results are shown in Table 1.

[Test Example 2] <Evaluation of grinding mark concealment>
The second release sheet was peeled from the protective film-forming sheet obtained in Examples and Comparative Examples to expose the protective film-forming film. While heating the protective film forming film on the polished surface of a # 2000 polished silicon wafer (diameter 200 mm, thickness 350 μm) to 70 ° C. using a tape mounter (Adwill RAD-3600 F / 12 manufactured by Lintec Corporation). After sticking, the first release sheet was peeled off. Then, the film was heated at 130 ° C. for 2 hours to cure the protective film-forming film to form a protective film, and a silicon wafer with a protective film was obtained.

The obtained 10 silicon wafers with a protective film were visually observed, and it was confirmed whether or not the grinding marks on the polished surface of the silicon wafer could be seen through the protective film. In all the silicon wafers with a protective film, those in which no grinding marks were visible were evaluated as having good grinding mark hiding property (A), and those in which even one grinding mark was visible were evaluated as having poor grinding mark hiding property (B). The results are shown in Table 1.

[Test Example 3] <Infrared inspection aptitude evaluation>
A dicing tape (Adwill D-175, manufactured by Lintec Corporation) was attached to the protective film surface side of the silicon wafer with a protective film obtained in Test Example 2. Then, the silicon wafer with a protective film was diced to a size of 3 mm × 3 mm and picked up to obtain a silicon chip with a protective film. The protective film side of the obtained silicon chip with a protective film is observed with an infrared microscope (manufactured by Olympus, BX-IR) to confirm whether the grinding marks and chipping of the silicon chip can be observed through the protective film, and the following criteria are used. The suitability for infrared inspection was evaluated in. The results are shown in Table 1.
A: Grinding marks could be clearly observed. In addition, chipping with a size of 5 μm or more and less than 10 μm from the side surface of the chip could be clearly observed.
B: Grinding marks could be clearly observed. Further, although chipping having a distance of 10 μm or more from the side surface of the chip could be clearly observed, chipping having a distance of 5 μm or more and less than 10 μm from the side surface of the chip was somewhat unclear.
C: Grinding marks could be observed to some extent. Further, chipping having a distance from the side surface of the chip of 5 μm or more and less than 10 μm could not be observed, and chipping having a distance from the side surface of the chip of 10 μm or more was somewhat unclear.
D: Grinding marks could not be observed, and chipping could not be observed regardless of the size.

As can be seen from Table 1, the protective film-forming film of the example in which the light transmittance at a wavelength of 550 nm is 20% or less and the light transmittance at a wavelength of 1600 nm is 25% or more is suitable for grinding mark concealment and infrared inspection. It was excellent for both.

The protective film-forming film and the protective film-forming (composite) sheet according to the present invention are suitably used for producing a chip having a protective film from a semiconductor wafer. Further, the inspection method according to the present invention is suitable for inspecting cracks and the like in a chip having a protective film.

1 ... Protective film forming film 2 ... Protective film forming sheet 21 ... Release sheet 3, 3A ... Protective film forming composite sheet 4 ... Adhesive sheet 41 ... Base material 42 ... Adhesive layer 5 ... Adhesive layer for jig 6 ... Semiconductor wafer 7 ... Ring frame

Claims (7)

The light transmittance at a wavelength of 1600 nm is 25% or more, and the light transmittance is 25% or more.
The light transmittance at a wavelength of 550 nm is 20% or less,
Contains 0.05 to 0.75% by mass of colorant,
A protective film-forming film containing a colorant and a filler having an average particle size of 0.01 to 2 μm. The protective film-forming film according to claim 1, wherein 0.05 to 0.5% by mass of a colorant is blended. The protective film-forming film according to claim 1 or 2,
A protective film-forming sheet comprising a release sheet laminated on one side or both sides of the protective film-forming film. An adhesive sheet in which an adhesive layer is laminated on one surface side of the base material,
A composite sheet for forming a protective film provided with a protective film-forming film laminated on the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet.
The light transmittance of the protective film forming film at a wavelength of 1600 nm is 25% or more.
The light transmittance of the protective film forming film at a wavelength of 550 nm is 20% or less.
The protective film-forming composite sheet is a composite sheet for forming a protective film, which comprises 0.05 to 0.75% by mass of a colorant and contains a filler having an average particle size of 0.01 to 2 μm. The composite sheet for forming a protective film according to claim 4, wherein the protective film-forming film contains 0.05 to 0.5% by mass of a colorant. A protective film is formed on the work by using the protective film forming film according to claim 1 or 2, the protective film forming sheet according to claim 3, or the protective film forming composite sheet according to claim 4 or 5. By manufacturing a workpiece with a protective film,
An inspection method characterized in that a work with a protective film or a work piece obtained by processing the work with a protective film is inspected through the protective film using infrared rays. The inspection method according to claim 6, wherein the work is a semiconductor wafer and the work piece is a semiconductor chip.

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