TW201706387A - Composite sheet for forming protective film - Google Patents

Abstract

The present invention provides a composite sheet for forming a protective film, including: a base material, an adhesive layer, and a protective film-forming film, wherein the adhesive layer is provided on the base material, and the protective film -forming film is provided on the adhesive layer; the adhesive sheet includes a (meth)acrylic acid alkyl ester copolymer at least in a layer which is in contact with the protective film-forming film, wherein the (meth)acrylic acid alkyl ester copolymer includes a structural unit derived from (meth)acrylic acid alkyl ester having 8 or more carbon atoms of an alkyl group which forms alkyl ester; and the composite sheet for forming the protective film is a sheet for use in manufacturing a semiconductor chip having a productive film, the manufacturing method including adhering the composite sheet for forming the protective film by the protective film-forming film on the back surface of a semiconductor wafer, forming the protective film by heat-curing the protective film-forming film, making the semiconductor chip by dicing the semiconductor wafer on which the protective film is formed, and after curing the adhesive layer by irradiating with an active energy ray, picking up the semiconductor chip together with the protective film which is adhered to the back surface thereof.

Description

Composite film for forming a protective film

The present invention relates to a composite sheet for forming a protective film for forming a protective film on the back surface of a semiconductor wafer.

Priority is claimed on Japanese Patent Application No. 2015-114714, filed on Jan.

In recent years, the industry has manufactured semiconductor devices using a mounting method called a so-called face down method. In the flip-chip method, a semiconductor wafer having electrodes such as bumps on a circuit surface is used, and the electrodes are bonded to the substrate. Therefore, there is a case where the back side of the opposite side of the circuit surface of the wafer is exposed.

A resin film made of an organic material is formed as a protective film on the back surface of the bare wafer, and is formed into a semiconductor wafer with a protective film and then incorporated into a semiconductor device. The purpose of using the protective film is to prevent cracking of the wafer after the dicing step or packaging, or to transfer the obtained wafer to a die pad portion or other semiconductor. On other components such as wafers.

On the other hand, the protective film is formed by using a composite sheet for forming a protective film, that is, the composite sheet for forming a protective film has an adhesive layer on a substrate, and is provided on the adhesive layer. A film for forming a protective film. In the composite sheet for forming a protective film, the film for forming a protective film has a function of forming a protective film, and the laminated structure of the substrate and the adhesive layer functions as a dicing sheet, and can be said as a film for forming a protective film. A composite sheet for forming a protective film which is formed integrally with a dicing sheet.

Such a composite sheet for forming a protective film is used, for example, in the following manner. In other words, the composite film for forming a protective film is attached to the back surface of the semiconductor wafer (the surface opposite to the electrode forming surface) by the film for forming a protective film, and then the semiconductor wafer is diced into a semiconductor wafer. Next, the active energy ray is irradiated to harden the adhesive layer, the semiconductor wafer is peeled off from the adhesive layer, and the semiconductor wafer is picked up. On the other hand, the film for forming a protective film is picked up together with the semiconductor wafer, and finally exists on the back surface of the semiconductor wafer in a state of being cured. In the composite sheet for forming a protective film, a composite sheet for forming a protective film which is used in the following manner is disclosed in which a film for forming a protective film is uncured or partially cured, and a semiconductor wafer is bonded. When the sealing material is cured, the uncured or partially cured film for forming a protective film is simultaneously or substantially completely cured (see Patent Document 1).

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2011-228450.

However, the conventional composite sheet for forming a protective film disclosed in Patent Document 1 has a problem in that, under certain conditions of use, especially after the adhesive layer is cured, the adhesive layer and the film for forming a protective film are peeled off. If the force is too large, the wafer may be cracked or chipped when the semiconductor wafer is picked up.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composite sheet for forming a protective film for forming a protective film on a back surface of a semiconductor wafer and having an adhesive layer on the substrate, on the adhesive layer. The film for forming a protective film, the peeling force of the adhesive film and the protective film forming film or the protective film after the protective film forming film is sufficiently large before the adhesive layer is cured, and can be stably cut and adhered The hardener layer is sufficiently small after hardening to stably pick up the semiconductor wafer.

In order to solve the problem, the present invention provides a composite sheet for forming a protective film, comprising an adhesive layer on a substrate, a film for forming a protective film on the adhesive layer, and the adhesive layer having active energy ray curability. The film for forming a protective film has thermosetting property; The conjugated sheet is used to produce a semiconductor wafer with a protective film, and the composite film for forming a protective film is attached to the back surface of the semiconductor wafer by the film for forming a protective film, and then the film for forming the protective film is cured by heating. After the protective film is formed, and then the semiconductor wafer is diced to form a semiconductor wafer, the adhesive layer is cured by irradiating the active energy ray, and then the semiconductor wafer is attached together with the protective film attached to the back surface of the semiconductor wafer. Picking up, thereby producing a semiconductor wafer with a protective film; the adhesive layer containing an alkyl (meth) acrylate copolymer, the aforementioned alkyl (meth) acrylate in at least a layer in contact with the film for forming a protective film The ester copolymer has a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more constituting the alkyl group of the alkyl ester.

In the composite sheet for forming a protective film of the present invention, the film for forming a protective film preferably contains an epoxy resin, a thermosetting agent, and an imidazole, and the thermosetting agent is dissolved by heating and exhibits curing activity to the epoxy resin.

In the composite sheet for forming a protective film of the present invention, it is preferred that the alkyl group constituting the alkyl ester has a carbon number of 11 to 18.

That is, the present invention encompasses the following aspects.

[1] A composite sheet for forming a protective film, comprising an adhesive layer on a substrate, a film for forming a protective film on the adhesive layer, the adhesive layer having active energy ray curability, and the protective film forming layer The film has a thermosetting property, and the composite film for forming a protective film is used for producing a semiconductor wafer with a protective film, and the protective film forming film is attached to the back surface of the semiconductor wafer by the protective film forming film. By heating to protect the aforementioned Forming a film for curing a film to form a protective film, and then cutting the semiconductor wafer to form a semiconductor wafer, and then curing the adhesive layer by irradiating an active energy ray, and then attaching the semiconductor wafer to the semiconductor wafer The protective film on the back surface is picked up together, thereby producing a semiconductor wafer with a protective film; the adhesive layer contains an alkyl (meth)acrylate copolymer in at least a layer in contact with the film for forming a protective film; The alkyl (meth) acrylate copolymer has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms constituting the alkyl group of the alkyl ester.

[2] The composite sheet for forming a protective film according to the above aspect, wherein the film for forming a protective film contains an epoxy resin, a thermosetting agent, and an imidazole, and the thermosetting agent is dissolved by heating and is attached to the ring. The oxygen resin shows hardening activity.

[3] The composite sheet for forming a protective film according to [1], wherein the alkyl group constituting the alkyl ester has a carbon number of 11 to 18.

According to the present invention, there is provided a composite sheet for forming a protective film, comprising: a protective film formed on a back surface of a semiconductor wafer; and an adhesive layer on the substrate; and a film for forming a protective film on the adhesive layer, the adhesive; The peeling force of the layer and the protective film forming film or the protective film after the film for forming a protective film (that is, the protective film of the cured film for forming the protective film) is sufficient before the adhesive layer is cured. It is large, and the cutting can be performed stably, and after the aforementioned adhesive layer is hardened, it is small enough to stably pick up the aforementioned semiconductor wafer.

1, 2, 3, 4‧‧‧ Composite film for protective film formation

10‧‧‧Support tablets

11‧‧‧Substrate

11a‧‧‧ Surface of the substrate

12, 32, 42‧‧‧ adhesive layer

12a, 32a, 42a‧‧‧ Surface of the adhesive layer

120a‧‧‧A film-side area for protective film formation

13, 23‧‧‧film for protective film formation

13a, 23a‧‧‧ Surface of film for protective film formation

130a‧‧‧A region on the adhesive layer side

14‧‧‧Release film

15‧‧‧Binder layer for fixtures

15a‧‧‧ Surface of the adhesive layer for the fixture

150a‧‧‧A film-side area for protective film formation

230a‧‧‧A zone for the adhesive layer side of the fixture

321, 421‧‧‧1st adhesive layer

322, 422‧‧‧2nd adhesive layer

322a, 422a‧‧‧ surface of the second adhesive layer

Fig. 1 is a cross-sectional view showing an embodiment of a composite sheet for forming a protective film of the present invention.

Fig. 2 is a cross-sectional view showing another embodiment of the composite sheet for forming a protective film of the present invention.

Fig. 3 is a cross-sectional view showing still another embodiment of the composite sheet for forming a protective film of the present invention.

Fig. 4 is a cross-sectional view showing still another embodiment of the composite sheet for forming a protective film of the present invention.

"Composite sheet for protective film formation"

The composite sheet for forming a protective film of the present invention comprises an adhesive layer on a substrate, a film for forming a protective film on the adhesive layer, the adhesive layer having active energy ray curability, and the film for forming a protective film. The composite film for forming a protective film is used for producing a semiconductor wafer with a protective film, and the protective film forming film is attached to the back surface of the semiconductor wafer by the film for forming a protective film. Heating the film for forming a protective film as a protective film, and then cutting the semiconductor wafer to form a semiconductor wafer, and then curing the adhesive layer by irradiating an active energy ray, and then attaching the semiconductor wafer to the foregoing The protective film on the back surface of the semiconductor wafer is picked up together, thereby manufacturing a semiconductor wafer with a protective film; the adhesive layer contains an alkyl (meth) acrylate copolymer in at least a layer in contact with the film for forming a protective film. ,before The (meth)acrylic acid alkyl ester copolymer has a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more constituting an alkyl group of the alkyl ester.

In one embodiment of the composite sheet for forming a protective film of the present invention, the substrate, the adhesive layer, and the film for forming a protective film are provided, and the adhesive layer is laminated on the substrate, and the protective film is formed. The adhesive layer has active energy ray curability, and contains at least a (meth)acrylic acid alkyl ester copolymer in a layer in contact with the protective film forming film; the (meth)acrylic acid The alkyl ester copolymer is a copolymer having a structural unit derived from an alkyl (meth)acrylate having 8 or more carbon atoms of an alkyl group constituting an alkyl ester; the film for forming a protective film has thermosetting property; A composite sheet for forming a protective film for producing a semiconductor wafer with a protective film, comprising the steps of: attaching the composite sheet for forming a protective film to a back surface of a semiconductor wafer by the film for forming a protective film; The protective film forming film in the composite sheet for forming a protective film to be attached is cured to form a protective film; the semiconductor wafer on which the protective film is formed is cut to form a semiconductor wafer; The adhesive layer is cured by irradiating an active energy ray, and then the semiconductor wafer is picked up together with the aforementioned protective film attached to the back surface of the semiconductor wafer. In the present specification, the laminated structure of the substrate and the adhesive layer may be referred to as a "support sheet". In addition, the composite sheet for forming a protective film is formed into a protective film by curing the film for forming a protective film by heating while maintaining the laminated structure of the base material, the adhesive layer or a cured product thereof, and the protective film. The composite sheet or the composite sheet obtained by curing the adhesive layer by irradiation of an active energy ray is also referred to as a composite sheet for forming a protective film.

In the composite sheet for forming a protective film of the present invention, the layer in contact with the film for forming a protective film in the adhesive layer contains a specific range of (meth)acrylic acid alkyl ester copolymer as described above, whereby the adhesive layer is adhered thereto. Before the layer of the protective layer is cured, the peeling force of the film for forming the protective film (ie, the protective film) after curing is sufficiently large, and the semiconductor wafer can be firmly and stably fixed, so that the wafer splash or the like is suppressed when the semiconductor wafer is diced. Cutting can be performed stably.

In addition, when the composite sheet for forming a protective film is used, the base material side of the composite sheet for forming a protective film may be formed before the semiconductor wafer is diced in a state in which a protective film is attached to the back surface of the semiconductor wafer. The protective film irradiates the laser beam and prints on the surface of the protective film (hereinafter sometimes referred to as "laser printing"). At this time, with the laser printing, the laser beam from the protective film is decomposed by the protective film to generate gas, but since the peeling force of the adhesive layer and the protective film is sufficiently large as described above, even if it is subjected to the generation The pressure of the gas, the peeling of the adhesive layer and the protective film are also suppressed, and the generation of the gas volume is suppressed. As a result, not only the dicing can be stably performed as described above, but also the printing applied to the protective film can be clearly visually recognized through the substrate and the adhesive layer.

On the other hand, in the composite sheet for forming a protective film of the present invention, the layer in contact with the film for forming a protective film in the adhesive layer contains a specific range of (meth)acrylic acid alkyl ester copolymer as described above. Therefore, after the adhesive layer is hardened, the peeling force of the cured product of the adhesive layer and the protective film is sufficient Small, the semiconductor wafer with the protective film can be picked up stably and easily, and the crack or the chip is cracked at the time of picking up.

Hereinafter, each configuration of the composite sheet for forming a protective film of the present invention will be described in detail.

<Substrate>

The material of the substrate is preferably various resins, and specific examples thereof include polyethylene (low density polyethylene (sometimes abbreviated as LDPE), linear low density polyethylene (sometimes abbreviated as LLDPE), and high density poly Ethylene (sometimes referred to as HDPE, etc.), polypropylene, ethylene-propylene copolymer, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride film, vinyl chloride copolymer, polyterephthalic acid Ethylene glycol, polyethylene naphthalate, polybutylene terephthalate, polyurethane, polyacrylic acid amide, polyimine, ethylene-vinyl acetate copolymer, ionic polymer Resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer, polystyrene, polycarbonate, fluororesin, hydride, modification, cross-linking of any of these resins or Copolymers, etc.

Further, in the present specification, the concept of "(meth)acrylic acid" includes both "acrylic acid" and "methacrylic acid".

The thickness of the substrate can be appropriately selected depending on the purpose, and is preferably from 50 μm to 300 μm, more preferably from 60 μm to 100 μm. When the thickness of the substrate is within the above range, the flexibility of the composite sheet for forming a protective film and the adhesion to a semiconductor wafer or a semiconductor wafer are further improved.

The "thickness" in the present specification can be obtained by a method specified in JIS K 7130:1999 (ISO 4593:1993).

The substrate may be composed of one layer (single layer) or may be composed of a plurality of layers of two or more layers. When the substrate is composed of a plurality of layers, the plurality of layers may be the same or different from each other. That is, all layers may be the same, or all layers may be different, and only a part of the layers may be the same. Further, when the plural layers are different from each other, the combination of these plural layers is not particularly limited. Here, the plural layers are different from each other, and at least one of the material and the thickness of each layer is different from each other.

Further, when the substrate is composed of a plurality of layers, the total thickness of each layer may be the above-mentioned preferred substrate thickness.

The surface of the substrate may be subjected to the following treatment to improve the adhesion to the adhesive layer provided on the substrate: roughening treatment by sand blasting, solvent treatment, etc.; corona discharge treatment, electron beam irradiation treatment, Oxidation treatment such as plasma treatment, ozone/ultraviolet irradiation treatment, flame treatment, chromic acid treatment, hot air treatment, and the like. Alternatively, the surface of the substrate may be subjected to a primer treatment.

<Adhesive layer>

The pressure-sensitive adhesive layer has active energy ray curability and contains an alkyl (meth) acrylate copolymer in at least the layer in contact with the film for forming a protective film. Wherein the (meth)acrylic acid alkyl ester copolymer has an alkyl (meth)acrylate having a carbon number of 8 or more from an alkyl group constituting the alkyl ester Derived structural unit.

By "derived" is meant a change in the chemical structure due to polymerization.

In the present specification, the "active energy ray" means an energy quantum in an electromagnetic wave or a charged particle beam, and examples thereof include ultraviolet rays, electron beams, and the like.

For example, a high-pressure mercury lamp, a Fusion H-type lamp, a xenon lamp, or the like can be used as the ultraviolet source. The electron beam can illuminate an electron beam generated by an electron beam accelerator or the like.

The thickness of the adhesive layer can be appropriately selected depending on the purpose, and is preferably from 1 μm to 100 μm, more preferably from 1 μm to 60 μm, particularly preferably from 1 μm to 30 μm.

The adhesive layer is formed of an adhesive composition containing the aforementioned (meth)acrylic acid alkyl ester copolymer or the like. The content ratio of the components which are not vaporized at normal temperature in the adhesive composition is usually the same as the content ratio of the aforementioned components in the adhesive layer. In the present specification, the term "normal temperature" means a temperature which is not particularly cold or particularly hot, that is, a normal temperature, and examples thereof include a temperature of 15 ° C to 25 ° C.

Next, the above-described adhesive composition containing the alkyl (meth)acrylate copolymer, and the components of the adhesive composition and the adhesive will be described.

[Adhesive composition]

(alkyl (meth) acrylate copolymer)

The alkyl (meth)acrylate copolymer has a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more constituting an alkyl group of the alkyl ester. In the present specification, unless otherwise specified, the term "alkyl (meth)acrylate" as used herein means "the number of carbon atoms of the alkyl group constituting the alkyl ester of 8 or more (meth)acrylic acid. Alkyl ester".

The alkyl group having 8 or more carbon atoms of the alkyl (meth)acrylate may be linear, branched or cyclic, and when it is cyclic, it may be monocyclic or polycyclic. One, but preferably linear or branched.

The number of carbon atoms of the alkyl group constituting the alkyl ester may be 8 or more, and may be, for example, 11 or more. Further, the number of carbon atoms of the alkyl group constituting the alkyl ester is preferably 18 or less. In other words, the carbon number of the alkyl group constituting the alkyl ester is preferably in the range of 8 to 18, and examples thereof are 11 to 18. The (meth)acrylic acid alkyl ester having 19 or more carbon atoms of the alkyl group constituting the alkyl ester has problems such as low solubility and is difficult to handle. In other words, when the number of carbon atoms of the alkyl group constituting the alkyl ester is 18 or less, the solubility is good and handling is easy.

Further, by using the above-mentioned (meth)acrylic acid alkyl ester copolymer having 8 or more carbon atoms of the alkyl group constituting the alkyl ester, and using the aforementioned (meth)acrylic acid alkyl ester copolymer having a carbon number of less than 7 In contrast, the adhesive layer has a low polarity. Therefore, when the film for forming a protective film contains a highly polar material such as an epoxy resin, it is possible to prevent the high-polarity material from being transferred from the film for protective film formation to the adhesive layer in the composite sheet for forming a protective film. The result can be effectively suppressed The thermosetting property of the film for forming a protective film is lowered. In addition, since the thermal curing degree of the film for forming a protective film is hardened by heating, the pick-up property of the semiconductor wafer with a protective film mentioned later is improved.

In the alkyl (meth)acrylate having 8 or more carbon atoms of the alkyl group, preferred examples thereof include n-octyl (meth)acrylate, isooctyl (meth)acrylate, and (meth)acrylic acid. 2-ethylhexyl ester, n-decyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, (meth)acrylic acid Dodecyl ester (also known as lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (also known as (meth)acrylic acid nutmeg) Ester), pentadecyl (meth)acrylate, cetyl (meth)acrylate (also known as palmityl (meth)acrylate), heptadecyl (meth)acrylate, (a) Octadecyl acrylate (also known as stearyl (meth) acrylate), isostearyl (meth) acrylate (also known as isostearyl (meth) acrylate), etc. The alkyl group is a chain alkyl (meth)acrylate; an isobornyl (meth)acrylate; a cycloalkyl (meth)acrylate such as dicyclopentanyl (meth)acrylate; and the like.

Among the above, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and isostearyl (meth)acrylate are preferred.

The (meth)acrylic acid alkyl ester copolymer may, for example, be an active energy ray-polymerizable copolymer which is polymerized by irradiation with an active energy ray. Preferred examples of such a copolymer include a hydroxyl group and a side chain having a polymerizable group (for example, (meth)acrylonitrile group or vinyl group (ethenyl) a copolymer of allyl (2-propenyl) or the like, preferably a (meth) acrylonitrile group; among these, more preferably having a hydroxyl group and being bonded to the side chain via a urethane bond A copolymer having a polymerizable group. Such an alkyl (meth)acrylate copolymer is crosslinked by, for example, reacting a hydroxyl group thereof with an isocyanate group in an isocyanate crosslinking agent to be described later. Further, such a (meth)acrylic acid alkyl ester copolymer has a polymerizable group in the side chain, and, for example, a low molecular weight active energy ray polymerizable compound is additionally used, and polymerization is carried out by irradiating an active energy ray. In contrast, the polymerization reaction can be carried out without using such a compound, whereby the adhesive layer after the polymerization is improved in peeling property from the protective film due to a decrease in adhesiveness, and the semiconductor wafer with the protective film can be easily picked up. The picking performance is improved. In addition, since it is not necessary to separately use a low molecular weight active energy ray-polymerizable compound, it is possible to suppress the transfer of such a low molecular weight active energy ray-polymerizable compound from the adhesive layer to the film for forming a protective film, and to suppress the film for forming a protective film. The characteristics change.

The above preferred alkyl (meth) acrylate copolymer is obtained, for example, by polymerizing these monomers using a composition comprising an alkyl (meth) acrylate and a hydroxyl group-containing monomer. After the copolymer (hereinafter sometimes referred to as "pre-copolymer"), the hydroxyl group of the copolymer (prepolymer) is reacted with an isocyanate group of a compound having an isocyanate group and a polymerizable group.

Among the aforementioned (meth)acrylic acid alkyl ester copolymers, more preferably, for example, The copolymer obtained by the following method: pre-copolymerization obtained by copolymerizing the above-mentioned (meth)acrylic acid alkyl ester and hydroxyl group-containing (meth) acrylate as essential monomers and copolymerizing these monomers The hydroxyl group of the substance reacts with an isocyanate group of a compound having an isocyanate group and a polymerizable group.

Examples of the hydroxyl group-containing (meth) acrylate include hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate.

Examples of the compound having an isocyanate group and a polymerizable group include 2-(meth)acryloxyethyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, and methacrylium. An isocyanate compound such as a isocyanate or an allyl isocyanate; among these, 2-methylpropenyloxyethyl isocyanate is preferred.

The above preferred alkyl (meth) acrylate copolymer may be obtained by reacting any of the above-mentioned necessary monomers and compounds with any other compound, and any of the above compounds may be, for example, a monomer. It can be a compound obtained by copolymerizing monomers. Examples of the monomer of any of the above-mentioned compounds include (meth) acrylate, (meth)acrylic acid, itaconic acid, and non-(methyl) which do not satisfy the alkyl (meth) acrylate and do not contain a hydroxyl group. Acrylic monomer and the like.

Examples of the hydroxyl group-free (meth) acrylate include, for example: Methyl)methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, (methyl) An alkyl (meth)acrylate such as heptyl acrylate, wherein the alkyl group constituting the alkyl ester in the alkyl (meth) acrylate is linear or branched and has a carbon number of 1 to 7; Arylalkyl (meth)acrylate such as benzyl acrylate; cycloalkenyl (meth) acrylate such as dicyclopentenyl (meth)acrylate; dicyclopentenyloxyethyl (meth)acrylate (meth)acrylic cycloalkenyloxyalkyl ester; (meth)acrylonitrile imine; glycidyl group-containing (meth)acrylate such as glycidyl (meth)acrylate.

Examples of the non-(meth)acrylic monomer include vinyl acetate, acrylonitrile, styrene, and N-methylol acrylamide.

The (meth)acrylic acid alkyl ester, the hydroxyl group-containing (meth) acrylate, the compound having an isocyanate group and a polymerizable group, and any of the foregoing compounds, etc., are used for preparing the aforementioned (meth)acrylic acid alkyl ester copolymer The components (that is, the constituent components of the copolymer) may be used alone or in combination of two or more.

The proportion of the alkyl (meth) acrylate having a carbon number of 8 or more is as follows: preferably 30% based on the total mass of all monomers used for preparing the alkyl (meth) acrylate copolymer. The mass% or more is more preferably 35% by mass or more.

In other words, the (meth)acrylic acid having a carbon number of 8 or more from the above alkyl group The content of the structural unit derived from the ester is preferably 30% by mass or more, and more preferably 35% by mass or more based on the total mass of all the structural units constituting the alkyl (meth) acrylate copolymer.

On the other hand, the upper limit of the content of the structural unit derived from the alkyl (meth)acrylate having 8 or more carbon atoms of the alkyl group is not particularly limited, and the alkyl (meth)acrylate is formed. The total mass of all the structural units of the copolymer may be selected from any of, for example, 85% by mass, 90% by mass, and 95% by mass, or may be 100% by mass.

That is, the ratio of the alkyl (meth) acrylate having a carbon number of 8 or more is as follows: relative to the total mass of all monomers used for preparing the alkyl (meth) acrylate copolymer 30% by mass or more and 100% by mass or less may be 30% by mass or more and 95% by mass or less, and may be 30% by mass or more and 90% by mass or less, and may be 30% by mass or more and 85% by mass or less.

On the other hand, the content may be 35 mass% or more and 100 mass% or less, may be 35 mass% or more and 95 mass% or less, may be 35 mass% or more and 90 mass% or less, or may be 35 mass% or more. 85 mass% or less.

In still another aspect, the content may be 40% by mass or more and 80% by mass or less.

In still another aspect, the content of the structural unit derived from the alkyl (meth) acrylate having 8 or more carbon atoms of the alkyl group is as follows: relative to all structural units constituting the alkyl (meth) acrylate copolymer The total mass may be 30% by mass or more and 100% by mass or less, or may be 30% by mass or less. The upper portion is 95% by mass or less, and may be 30% by mass or more and 90% by mass or less, and may be 30% by mass or more and 85% by mass or less.

In another aspect, the content may be 35 mass% or more and 100 mass% or less, may be 35 mass% or more and 95 mass% or less, may be 35 mass% or more and 90 mass% or less, or may be 35 mass% or more. 85 mass% or less.

In still another aspect, the content may be 40% by mass or more and 80% by mass or less.

The alkyl (meth) acrylate copolymer contained in the pressure-sensitive adhesive layer may be used alone or in combination of two or more.

The content of the (meth)acrylic acid alkyl ester copolymer is preferably 75% by mass or more, and more preferably 80% by mass or more based on the total mass of the pressure-sensitive adhesive layer. Further, in order to form such an adhesive layer, the content of the aforementioned (meth)acrylic acid alkyl ester copolymer in the above-mentioned adhesive composition is higher than the total mass of all components except the solvent in the above-mentioned adhesive composition. Preferably, it is 75 mass% or more, more preferably 80 mass% or more.

On the other hand, the upper limit of the content of the (meth)acrylic acid alkyl ester copolymer in the pressure-sensitive adhesive layer is not particularly limited, and may be 100% by mass based on the total mass of the pressure-sensitive adhesive layer, but it is considered as The other components are used in the same manner as described later, and the above upper limit is preferably 97% by mass, more preferably 95% by mass.

That is, the content of the aforementioned alkyl (meth) acrylate copolymer is relative to The total mass of the pressure-sensitive adhesive layer may be 75 mass% or more and 100 mass% or less, preferably 75 mass% or more and 97 mass% or less, more preferably 80 mass% or more and 95 mass% or less.

In another aspect, the content of the (meth)acrylic acid alkyl ester copolymer in the adhesive composition is 75% by mass or more and 100% by mass based on the total mass of all components other than the solvent in the adhesive composition. The content may be at most or less, preferably from 75% by mass to 97% by mass, more preferably from 80% by mass to 95% by mass.

When the (meth)acrylic acid alkyl ester copolymer has a hydroxyl group and further has a polymerizable group in the side chain, preferred examples of the above-mentioned adhesive composition include, in addition to the aforementioned (meth)acrylic acid alkyl ester copolymerization. In addition to the material, a composition of an isocyanate crosslinking agent and a photopolymerization initiator is further contained.

(isocyanate crosslinking agent)

The isocyanate crosslinking agent is not particularly limited as long as it is a crosslinking agent having an isocyanate group (-N=C=O), and preferably, for example, 2,4-toluene diisocyanate; 2,6-toluene diisocyanate ; 1,3-benzenedimethyl diisocyanate; 1,4-dimethylbenzene diisocyanate; diphenylmethane-4,4'-diisocyanate; diphenylmethane-2,4'-diisocyanate; 3-methyl Diphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane-4,4'-diisocyanate; dicyclohexylmethane-2,4'-diisocyanate; Add all or part of the hydroxyl groups of a polyol such as methylolpropane to toluene diisocyanate, hexamethylene diisocyanate and benzene dimethyl A compound of at least one of a diisocyanate; an isocyanate diisocyanate or the like.

The isocyanate crosslinking agent contained in the adhesive composition may be one type or two or more types.

The content of the isocyanate crosslinking agent in the adhesive composition is preferably such that the content of the isocyanate crosslinking agent is 0.01 by mass when the content of the alkyl (meth)acrylate copolymer is 100 parts by mass. The amount is from 20 parts by mass, more preferably from 0.1 part by mass to 10 parts by mass.

(photopolymerization initiator)

The photopolymerization initiator may be a known photopolymerization initiator, and specific examples thereof include 4-(2-hydroxyethoxy)-phenyl-(2-hydroxy-2-propyl) ketone. --hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1-{4-[4-(2 Α-keto alcohol compound such as -hydroxy-2-methyl-propenyl)-benzyl]phenyl}-2-methyl-propan-1-one; methoxyacetophenone, 2,2-di Methoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane- An acetophenone compound such as 1-ketone; a benzoin ether compound such as benzoin ethyl ether, benzoin isopropyl ether, aniseed methoxyether; a ketal compound such as benzoin dimethyl ketal; 2-naphthalene sulfonium chloride An aromatic sulfonium chloride compound; a photoactive lanthanide compound such as 1-benzophenone-1,1-propanedione-2-(o-ethoxycarbonyl)anthracene; diphenyl ketone or benzamidine benzoic acid; 3,3'-dimethyl-4-methoxydiphenyl Diphenyl ketone compound such as ketone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2 a thioxanthone compound such as 4-dichlorothioxanthone, 2,4-diethylthioxanthone or 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketone; fluorenylphosphine oxide; Mercaptophosphonate and the like.

The content of the photopolymerization initiator in the above-mentioned adhesive composition is preferably from 0.05 parts by mass to 20 parts by mass, based on 100 parts by mass of the alkyl (meth)acrylate copolymer.

(solvent)

The adhesive composition preferably further contains a solvent in addition to the alkyl (meth)acrylate copolymer.

The solvent is not particularly limited, and examples of preferred solvents include hydrocarbons having 7 to 9 carbon atoms such as toluene and xylene; methanol, ethanol, 2-propanol, and isobutanol (also known as 2-methylpropane). 1 to 6 alcohols such as 1-alcohol) and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; dimethylformamide and N-methylpyrrole A guanamine such as a ketene (that is, a compound having a guanamine bond) or the like.

Among the above, methyl ethyl ketone, toluene, and ethyl acetate are preferred.

The solvent contained in the adhesive composition may be one type or two or more types.

The content of the solvent when the adhesive composition contains a solvent is preferably The concentration of the solid content of the composition is from 10% by mass to 50% by mass based on the total mass of the composition.

(other ingredients)

In addition to the alkyl (meth)acrylate copolymer, the above-mentioned adhesive composition may contain an isocyanate-based crosslinking agent, a photopolymerization initiator, and the like without departing from the effects of the present invention. Other ingredients of any of the solvents.

The other components may be any known components, and may be arbitrarily selected according to the purpose, and are not particularly limited. Preferred examples thereof include dyes, pigments, anti-deterioration agents, antistatic agents, flame retardants, polyoxyxides, and chain transfer. Various additives such as agents.

The pressure-sensitive adhesive layer may be composed of one layer (single layer) or a plurality of layers of two or more layers. When the adhesive layer is composed of a plurality of layers, the plurality of layers may be the same or different from each other. That is, all layers may be the same, or all layers may be different, and only a part of the layers may be the same. Further, when the plural layers are different from each other, the combination of these plural layers is not particularly limited. Here, the phrase "the plural layers are different from each other" has the same meaning as the above substrate.

In the case where the adhesive layer is composed of one layer (single layer), the adhesive layer must be a layer containing the alkyl (meth) acrylate copolymer obtained by using the above adhesive composition. Further, when the adhesive layer is composed of a plurality of layers, at least the film for forming a protective film is in contact with the plurality of layers. The layer (that is, the layer farthest from the substrate in the thickness direction of the adhesive layer, hereinafter sometimes referred to as the uppermost layer) must be obtained by using the above-mentioned adhesive composition to contain the aforementioned alkyl (meth)acrylate. a layer of copolymer. When the pressure-sensitive adhesive layer is composed of a plurality of layers, one or more layers other than the layer in contact with the film for forming a protective film may be all layers containing the alkyl (meth) acrylate copolymer, or all of them may be excluded ( The layer of the alkyl (meth) acrylate copolymer may be a part of the layer containing the alkyl (meth) acrylate copolymer.

When the pressure-sensitive adhesive layer is composed of a single layer, the configuration of the composite sheet for forming a protective film is simplified, and therefore it is advantageous in that it can be produced at low cost.

On the other hand, when the pressure-sensitive adhesive layer is composed of a plurality of layers, the layer (ie, the uppermost layer) in contact with the film for forming a protective film in the plurality of layers is contained in the above-mentioned (meth)acrylic acid alkyl group. The layer of the ester copolymer is obtained to obtain the effects of the present invention. Further, a layer in contact with the substrate in the plurality of layers (that is, a layer adjacent to the substrate in the thickness direction of the adhesive layer, hereinafter sometimes referred to as a lowermost layer) is, for example, a substrate The layer having particularly high adhesion is further improved in stability when the composite sheet for forming a protective film is used. In the same manner, the adhesive layer is a laminate composed of a plurality of layers, and has an advantage that the adhesive layer can be adjusted to have a layer having two or more characteristics as a whole.

When the adhesive layer is composed of a plurality of layers, the adhesive layer not containing the aforementioned alkyl (meth) acrylate copolymer may be, for example, the same as the previous adhesive layer Layer.

When the adhesive layer is composed of a plurality of layers, the total thickness of each layer may be the thickness of the above preferred adhesive layer.

<film for forming a protective film>

The film for forming a protective film may have thermosetting properties, may have pressure-sensitive adhesive properties, or may be softened by heating to be attached to various adherends. After the film for forming a protective film is thermally cured, it finally becomes a protective film having high impact resistance. The protective film is excellent in shear strength and can maintain sufficient adhesive properties even under severe high temperature and high humidity conditions.

The thickness of the film for forming a protective film is not particularly limited, but is preferably 1 μm to 100 μm, more preferably 5 μm to 75 μm, and particularly preferably 5 μm to 50 μm. When the thickness of the film for forming a protective film is not less than the above lower limit value, the adhesion force to the semiconductor wafer and the semiconductor wafer which is an adherend becomes larger. In addition, when the thickness of the film for forming a protective film is equal to or less than the above upper limit value, when the semiconductor wafer is picked up, the protective film as a cured product can be more easily cut by the shear force.

The film for forming a protective film is not particularly limited as long as it is a film having thermosetting properties.

As a film for forming a protective film, a film containing a polymer component (A) and a thermosetting component (B) is mentioned, for example. Polymer component (A) is visible It is a component formed by the polymerization reaction of a polymeric compound.

Further, the thermosetting component (B) is a component which can be subjected to a curing (polymerization) reaction by heat. Further, the polymerization reaction in the present invention also includes a polycondensation reaction.

[Composition for forming a protective film]

The film for forming a protective film can be formed of a composition for forming a protective film containing a component constituting the film for forming a protective film. The content ratio of the components which are not vaporized at normal temperature in the composition for forming a protective film is usually the same as the content ratio of the components of the film for forming a protective film.

The composition for forming a protective film is preferably a composition containing the polymer component (A) and the thermosetting component (B), and more preferably a polymer component (A) or a thermosetting component (B). And a composition of the hardening accelerator (C). Hereinafter, the components contained in the protective film-forming composition and the protective film-forming film will be described.

(polymer component (A))

The polymer component (A) is a polymer compound for imparting film formability or flexibility to the film for forming a protective film. The polymer component (A) sometimes also belongs to the thermosetting component (B).

For example, a phenoxy resin or an acrylic resin having an epoxy group in a side chain belongs to the polymer component (A) and may also belong to the thermosetting component (B). Such a component can be treated as the polymer component (A).

The polymer component (A) may be used alone or in combination of two or more.

Examples of the polymer component (A) include an acrylic resin, a polyester, a polyurethane, an urethane acrylate resin, a polyoxyxylene resin, a rubber-based polymer, a phenoxy resin, and the like; It is an acrylic resin.

As the acrylic resin, a known acrylic polymer can be used.

The weight average molecular weight (Mw) of the acrylic resin is preferably from 10,000 to 2,000,000, more preferably from 100,000 to 1,500,000. When the weight average molecular weight of the acrylic resin is at least the above lower limit value, the adhesion between the protective film described later and the cured adhesive layer is suppressed, and the pick-up property of the semiconductor wafer with the protective film is further improved.

In addition, when the weight average molecular weight of the acrylic resin is equal to or less than the above-described upper limit, the film for forming a protective film easily follows the uneven surface of the adherend, thereby further suppressing occurrence of a gap between the adherend and the film for forming a protective film. .

In the present specification, the term "weight average molecular weight" means a polystyrene equivalent value measured by a gel permeation chromatography (GPC) method unless otherwise specified.

The glass transition temperature (Tg) of the acrylic resin is preferably from -60 ° C to 70 ° C, more preferably from -30 ° C to 50 ° C. When the Tg of the acrylic resin is at least the above lower limit value, the peeling force of the protective film to be described later and the adhesive layer after curing is reduced, and the pick-up property of the semiconductor wafer with the protective film is further improved. improve. In addition, when the Tg of the acrylic resin is equal to or less than the above upper limit, the adhesion between the film for forming a protective film and the semiconductor wafer is increased, and the semiconductor wafer can be more stably fixed.

Examples of the monomer constituting the acrylic resin include an alkyl (meth)acrylate having an alkyl group constituting an alkyl ester and having a carbon number of 1 to 18, and methyl (meth)acrylate. Ethyl acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylate Octyl ester, n-decyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate Base ester, cetyl (meth) acrylate (palmityl (meth) acrylate), heptadecyl (meth) acrylate, octadecyl (meth) acrylate ((meth) acrylate (stearyl ester), etc.; (meth) acrylate having a cyclic skeleton, cycloalkyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, (methyl) Dicyclopentyl acrylate, (methyl) Dicyclopentenyl enoate, dicyclopentenyloxyethyl (meth)acrylate, (meth) acrylimide, etc.; hydroxyl-containing (meth) acrylate, hydroxymethyl (meth) acrylate And 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, etc.; glycidyl group-containing (meth)acrylate, glycidyl (meth)acrylate, and the like.

In addition, the acrylic resin may also be acrylic acid, methacrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylol acrylamide The monomer is copolymerized.

The monomer constituting the acrylic resin may be one type or two or more types.

The acrylic resin may have a functional group which may be bonded to another compound such as a vinyl group, a (meth) acrylonitrile group, an amine group, a hydroxyl group, a carboxyl group or an isocyanate group. The functional group may be bonded to another compound via a crosslinking agent (F) to be described later, or may be directly bonded to another compound without passing through the crosslinking agent (F). When the acrylic resin is bonded to another compound by the above functional group, the package reliability of the semiconductor device obtained by using the composite sheet for forming a protective film tends to be improved.

When the composition for forming a protective film contains an acrylic resin as the polymer component (A), the content of the acrylic resin in the protective film-forming composition is all the components other than the solvent in the protective film-forming composition. The total mass is preferably from 5% by mass to 50% by mass. When the content of the acrylic resin is in the above range, the peeling force of the protective film and the adhesive layer after curing becomes small, and the pick-up property of the semiconductor wafer with the protective film is further improved.

When the film for forming a protective film contains the acrylic resin as the polymer component (A), the content of the acrylic resin in the film for forming a protective film is preferably 5% by mass based on the total mass of the film for forming a protective film. 50% by mass.

In the present invention, the pickup property of the semiconductor wafer with the protective film is further improved by reducing the adhesion force (sometimes referred to as a peeling force) of the protective film and the adhesive layer after curing. Or the film for forming a protective film can easily follow the uneven surface of the adherend, and further suppress the occurrence of a gap or the like between the adherend and the film for forming a protective film, and the polymer component (A) can be used alone. A thermoplastic resin other than the acrylic resin (hereinafter sometimes referred to simply as "thermoplastic resin") may be used together with the acrylic resin.

The weight average molecular weight of the aforementioned thermoplastic resin is preferably from 1,000 to 100,000, more preferably from 3,000 to 80,000.

The glass transition temperature (Tg) of the aforementioned thermoplastic resin is preferably from -30 ° C to 150 ° C, more preferably from -20 ° C to 120 ° C.

Examples of the thermoplastic resin include polyester, polyurethane, phenoxy resin, polybutene, polybutadiene, and polystyrene.

The thermoplastic resin may be used singly or in combination of two or more kinds.

(thermosetting component (B))

The thermosetting component (B) is a component for forming a hard protective film by curing the film for forming a protective film. The thermosetting component (B) sometimes belongs to the poly The component (A) is treated as a polymer component (A).

The thermosetting component (B) may be used alone or in combination of two or more.

Examples of the thermosetting component (B) include an epoxy thermosetting resin, a thermosetting polyimide resin, a polyurethane, an unsaturated polyester, a polyoxy resin, and the like; Epoxy thermosetting resin.

‧Epoxy thermosetting resin

The epoxy thermosetting resin is composed of an epoxy resin (B11) and a thermosetting agent (B12).

The epoxy-based thermosetting resin may be used singly or in combination of two or more kinds.

The epoxy resin (B11) is exemplified, and examples thereof include the following bifunctional or higher epoxy compounds: polyfunctional epoxy resin, biphenyl compound, bisphenol A diglycidyl ether and hydrogenated product thereof, and adjacent Phenolic novolac epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenyl skeleton type epoxy resin, and the like. Among the above, a bisphenol A type epoxy resin and a dicyclopentadiene type epoxy resin are preferable.

As the epoxy resin (B11), an epoxy resin having an unsaturated hydrocarbon group can also be used.

As the epoxy resin having an unsaturated hydrocarbon group, for example, a plurality of officials A compound in which a part of the epoxy group of the epoxy resin is replaced with a group containing an unsaturated hydrocarbon group.

The number average molecular weight of the epoxy resin (B11) is not particularly limited, and is preferably from 100 to 20,000 from the viewpoint of the curability of the film for forming a protective film and the strength and heat resistance of the protective film after curing.

The "number average molecular weight" as used herein is a polystyrene-converted value measured by a gel permeation chromatography (GPC) method.

The epoxy equivalent of the epoxy resin (B11) is preferably from 100 g/eq to 1100 g/eq, more preferably from 150 g/eq to 1000 g/eq.

Epoxy resin (B11) may be used alone or in combination of two or more.

The heat hardener (B12) functions as a hardener for the epoxy resin (B11).

The thermosetting agent (B12) is, for example, a compound having two or more functional groups reactive with an epoxy group in one molecule. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amine group, a carboxyl group, and a group in which an acid group is formed by an anhydride; and preferably a phenolic hydroxyl group, an amine group, or an acid group is formed by an anhydride. More preferably, it is a phenolic hydroxyl group or an amine group, and particularly preferably an amine group.

In the thermosetting agent (B12), examples of the phenolic curing agent having a phenolic hydroxyl group include a polyfunctional phenol resin, a biphenol, and a novolak type phenol resin. , a dicyclopentadiene phenol resin, an aralkyl phenol resin, and the like.

In the thermosetting agent (B12), examples of the amine-based curing agent having an amine group include dicyandiamide (hereinafter sometimes abbreviated as "DICY").

The heat hardener (B12) may also be one having an unsaturated hydrocarbon group.

Examples of the thermosetting agent (B12) having an unsaturated hydrocarbon group include a compound in which a part of the hydroxyl group of the phenol resin is substituted with a group having an unsaturated hydrocarbon group; and an aromatic ring of the phenol resin is directly bonded to have an unsaturated hydrocarbon group. a compound such as a base.

The aforementioned unsaturated hydrocarbon group in the heat hardener (B12) is the same as the unsaturated hydrocarbon group in the above epoxy resin having an unsaturated hydrocarbon group.

The heat curing agent (B12) may be used singly or in combination of two or more.

The heat hardener (B12) is preferably solid at normal temperature, and does not exhibit hardening activity for the epoxy resin (B11), on the other hand, dissolves by heating, and shows heat of hardening activity to the epoxy resin (B11). A curing agent (hereinafter sometimes referred to simply as "solid dispersion type latent curing agent"). In other words, the film for forming a protective film preferably contains the epoxy resin (B11) and the solid dispersion type latent curing agent as the heat curing agent (B12).

The solid dispersion type latent curing agent is stably dispersed in the epoxy resin (B11) in the film for forming a protective film at room temperature, but is compatible with the epoxy resin (B11) by heating, and is epoxy resin ( B11) The reaction is carried out. By The storage stability of the composite sheet for forming a protective film is remarkably improved by using the solid dispersion type latent curing agent. For example, it is possible to suppress the transfer of the curing agent from the film for forming a protective film to the adjacent adhesive layer, and it is possible to effectively suppress the decrease in the thermosetting property of the film for forming a protective film. In addition, the degree of thermal hardening of the film for forming a protective film to be cured by heating is further improved, so that the pick-up property of the semiconductor wafer with a protective film described later is further improved.

Examples of the solid dispersion type latent curing agent include an onium salt, a dibasic acid hydrazine, a dicyandiamide, and an amine adduct of a curing agent.

The content of the thermosetting agent (B12) in the film for forming a protective film and the film for forming a protective film is as follows: when the content of the epoxy resin (B11) is 100 parts by mass, it is preferably from 0.1 part by mass to 500 parts by mass. More preferably, it is 1 part by mass to 200 parts by mass. When the content of the heat curing agent (B12) is at least the above lower limit value, the curing of the film for forming a protective film becomes easier.

In addition, when the content of the heat curing agent (B12) is at most the above upper limit value, the moisture absorption rate of the film for forming a protective film is lowered, and the package reliability is further improved.

The content of the thermosetting component (B) in the film for forming a protective film and the film for forming a protective film is as follows: when the content of the polymer component (A) is 100 parts by mass, it is preferably from 1 part by mass to 100% by mass. The portion is more preferably from 1.5 parts by mass to 85 parts by mass, particularly preferably from 2 parts by mass to 70 parts by mass. By setting the aforementioned content of the thermosetting component (B) to the above range, the protective film and the cured film The adhesion force (peeling force) of the above-mentioned adhesive layer is further reduced, and the pick-up property of the semiconductor wafer with the protective film is further improved.

(hardening accelerator (C))

The hardening accelerator (C) is a component for adjusting the curing rate of the composition for forming a protective film.

Examples of preferred curing accelerators (C) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dimethylolimidazole, 2-phenyl-4-methyl-5- An imidazole such as hydroxymethylimidazole (i.e., an imidazole in which at least one hydrogen atom is substituted by a group other than a hydrogen atom); an organic phosphine such as tributylphosphine, diphenylphosphine or triphenylphosphine (at least one hydrogen atom) An organic group-substituted phosphine); a tetraphenylboronium salt such as tetraphenylphosphonium tetraphenylborate or triphenylphosphine tetraphenylborate; and the like.

Among the above, 2-phenyl-4,5-dimethylolimidazole is preferred.

The curing accelerator (C) may be used singly or in combination of two or more.

When the protective film-forming composition contains the solid dispersion type latent curing agent as the heat curing agent (B12), it is preferred to contain the imidazole as the curing accelerator (C). In other words, the film for forming a protective film preferably contains the epoxy resin (B11), the solid dispersion type latent curing agent as the heat curing agent (B12), and the imidazole as the curing accelerator (C).

In other words, the protective film forming film contains the polymer component (A), the epoxy resin (B11), the above-mentioned solid dispersion type latent curing agent as the heat curing agent (B12), and the curing accelerator (C). The imidazoles.

When the curing accelerator (C) is used, the content of the curing accelerator (C) in the protective film-forming composition and the protective film-forming film is as follows: when the content of the thermosetting component (B) is 100 parts by mass, It is preferably from 0.01 part by mass to 10 parts by mass, more preferably from 0.1 part by mass to 4 parts by mass. When the content of the curing accelerator (C) is in the above range, the film for forming a protective film has excellent adhesion characteristics even under high temperature and high humidity conditions, and can be achieved even when exposed to severe reflow conditions. High package reliability. When the content of the curing accelerator (C) is at least the above lower limit value, a more remarkable effect by the use of the curing accelerator (C) can be obtained. In addition, although the curing accelerator (C) usually has a high polarity, the curing accelerator (C) can be suppressed under high temperature and high humidity conditions by setting the content of the curing accelerator (C) to be equal to or less than the above upper limit. In the film for forming a protective film, the interface with the adherend is deposited, whereby the reliability of the package is improved.

In order to improve various physical properties of the film for forming a protective film, the film for forming a protective film may be contained in addition to the polymer component (A), the thermosetting component (B), and the curing accelerator (C), and may optionally contain these components. The composition for forming a protective film of the other components is formed.

Examples of the other components contained in the protective film-forming composition and the protective film-forming film include a filler (D) and a coupling agent (E). Crosslinking agent (F), general additive (G), and the like.

(filling material (D))

In general, it is easy to adjust the thermal expansion coefficient of the composition for forming a protective film by including the filler (D). Therefore, by using such a composition for forming a protective film, the thermal expansion coefficient of the cured protective film is most suitable for the semiconductor wafer, and the package reliability can be improved.

Further, in general, by using the composition for forming a protective film containing the filler (D), the moisture absorption rate of the cured protective film can be lowered.

The filler (D) may be any of an organic filler and an inorganic filler, preferably an inorganic filler.

Examples of preferred inorganic fillers include powders of cerium oxide, aluminum oxide, talc, calcium carbonate, titanium white, iron oxide, cerium carbide, and boron nitride; and spheroidization of these cerium oxides and the like Beads; single crystal fibers such as cerium oxide; glass fibers, and the like.

Among these, the inorganic filler is preferably a cerium oxide filler or an alumina filler.

The filler (D) may be used singly or in combination of two or more.

When the filler (D) is used, the content of the filler (D) (ie, protection) is relative to the total mass of the components other than the solvent in the composition for forming a protective film. The content of the filler (D) in the film for film formation is preferably from 5% by mass to 80% by mass, more preferably from 7% by mass to 60% by mass. By setting the content of the filler (D) to the above range, it is easier to adjust the above thermal expansion coefficient.

(coupler (E))

By using a compound having a functional group reactive with an inorganic compound or an organic compound as the coupling agent (E), the adhesion of the film for forming a protective film to the adherend and the adhesion can be improved. In addition, the protective film obtained by curing the film for forming a protective film containing the coupling agent (E) has improved water resistance without impairing heat resistance.

The coupling agent (E) is preferably a compound having a functional group reactive with a functional group possessed by the polymer component (A) or the thermosetting component (B), and more preferably a decane coupling agent.

Preferred examples of the decane coupling agent include γ-glycidoxypropyltrimethoxydecane, γ-glycidoxypropylmethyldiethoxydecane, and β-(3,4-ring). Oxycyclohexyl)ethyltrimethoxydecane, γ-(methacryloxypropyl)trimethoxynonane, γ-aminopropyltrimethoxydecane, N-6-(aminoethyl)-γ- Aminopropyltrimethoxydecane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxydecane, N-phenyl-γ-aminopropyltrimethoxydecane, γ-ureido Propyltriethoxydecane, γ-mercaptopropyltrimethoxydecane, γ-mercaptopropylmethyldimethoxydecane, bis(3-triethoxydecylpropyl)tetrasulfide, methyl Trimethoxydecane, methyltriethoxydecane, vinyltrimethoxydecane, vinyltriethoxydecane , imidazolium, and the like.

The coupling agent (E) may be used singly or in combination of two or more.

When the coupling agent (E) is used, the content of the coupling agent (E) in the protective film-forming composition and the protective film-forming film is as follows: the total content of the polymer component (A) and the thermosetting component (B) is set. When it is 100 parts by mass, it is preferably 0.03 parts by mass to 20 parts by mass, more preferably 0.05 parts by mass to 10 parts by mass, particularly preferably 0.1 part by mass to 5 parts by mass. When the content of the coupling agent (E) is at least the above lower limit value, a more remarkable effect by using the coupling agent (E) can be obtained, and the aforementioned content of the coupling agent (E) is as described above. Below the limit value, generation of outgassing can be further suppressed.

(crosslinking agent (F))

When the above-mentioned acrylic resin having a functional group capable of bonding with another compound, for example, a functional group such as a vinyl group, a (meth) acryl fluorenyl group, an amine group, a hydroxyl group, a carboxyl group or an isocyanate group, is used as the polymer component (A), In order to cause crosslinking of the functional group with other compounds, a crosslinking agent (F) can be used. By using the crosslinking agent (F) to cause crosslinking, the initial adhesion force and cohesive force of the film for forming a protective film can be adjusted.

Examples of the crosslinking agent (F) include an organic polyvalent isocyanate compound and an organic polyimine compound.

Examples of the organic polyvalent isocyanate compound include an aromatic polyisocyanate compound, an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, and terpolymers, isocyanurate bodies, and adducts of these compounds (with B). a reaction product of a low molecular weight active hydrogen compound such as diol, propylene glycol, neopentyl glycol, trimethylolpropane or castor oil, for example, a dimethylated diisocyanate adduct of trimethylolpropane, etc.) A terminal isocyanate urethane prepolymer obtained by reacting an organic polyvalent isocyanate compound with a polyol compound.

The organic polyisocyanate compound may, for example, be 2,4-toluene diisocyanate; 2,6-toluene diisocyanate; 1,3-benzenedimethyl diisocyanate; 1,4-xylene diisocyanate; diphenyl group. Methane-4,4'-diisocyanate; diphenylmethane-2,4'-diisocyanate; 3-methyldiphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; bicyclic Hexylmethane-4,4'-diisocyanate; dicyclohexylmethane-2,4'-diisocyanate; addition of toluene diisocyanate and hexamethylene group to all or a part of hydroxyl groups of polyhydric alcohols such as trimethylolpropane A compound of either or both isocyanates; an isocyanate diisocyanate or the like.

The organic polyimine compound may, for example, be N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide) or trimethylolpropane-tri-beta-nitrogen. Propidyl propionate, tetramethylolmethane-tri-β-aziridine propionate, N,N'-toluene-2,4-bis(1-aziridinecarbamamine) Based on melamine and the like.

When the isocyanate crosslinking agent is used as the crosslinking agent (F), it is preferred to use a hydroxyl group-containing polymer as the acrylic resin as the polymer component (A). When the crosslinking agent (F) has an isocyanate group and the acrylic resin has a hydroxyl group, the crosslinked structure can be easily introduced into the film for forming a protective film by the reaction of the crosslinking agent (F) with the acrylic resin. .

When the crosslinking agent (F) is used, the content of the crosslinking agent (F) in the composition for forming a protective film is as follows: when the content of the polymer component (A) is 100 parts by mass, it is preferably 0.01 parts by mass to 20 parts by mass. The parts by mass are more preferably from 0.1 part by mass to 10 parts by mass, particularly preferably from 0.5 part by mass to 5 parts by mass.

(General additive (G))

Examples of the general additive (G) include a known plasticizer, an antistatic agent, an antioxidant, a pigment, a dye, a getter, and the like.

(solvent)

Since the composition for forming a protective film can be improved in workability by dilution, it is preferable to further contain a solvent.

The solvent contained in the composition for forming a protective film may be the same as the solvent in the above-mentioned adhesive composition.

The solvent contained in the composition for forming a protective film may be one type or two or more types.

The solvent content in the case where the protective film forming composition contains a solvent is preferably The concentration of the solid content of the protective film-forming composition is from 35% by mass to 75% by mass based on the total mass of the protective film-forming composition.

In other words, the protective film forming composition includes a polymer component (A), a thermosetting component (B), a curing accelerator (C), and optionally a solvent, a filler (D), and At least one component selected from the group consisting of a coupling agent (E), a crosslinking agent (F), and a general additive (G).

Another aspect of the film for forming a protective film includes a polymer component (A), a thermosetting component (B), a curing accelerator (C), and optionally, a filler (D), a coupling agent (E), and At least one component selected from the group consisting of a crosslinking agent (F) and a general additive (G).

Furthermore, it is preferable that the thermosetting component (B) contains the epoxy resin (B11) and the solid dispersion type latent curing agent as the thermal curing agent (B12), and the curing accelerator (C) contains an imidazole.

The protective film-forming composition can be obtained by blending the above-mentioned respective components for constituting the composition. For example, it can be obtained by the same method as the above-described adhesive composition except for the difference in the formulation components.

When a solvent is used, the solvent may be mixed with any of the formulation components other than the solvent, and the formulation component may be previously diluted and used, or the solvent may be used in combination with the formulation component without any dilution of the solvent. Formulation ingredients.

The composite sheet for forming a protective film may have a release film, for example, on the surface of the film for forming a protective film or the surface of the adhesive layer. When the composite sheet for forming a protective film is used, the release film may be peeled off (removed).

Fig. 1 is a cross-sectional view showing an embodiment of a composite sheet for forming a protective film of the present invention.

The composite sheet 1 for forming a protective film shown in the present invention has an adhesive layer 12 on a substrate 11 and a film 13 for forming a protective film on the adhesive layer 12, and has an adhesive for the support sheet 10. The layer 12 is provided with a film 13 for forming a protective film. In addition, the protective film forming composite sheet 1 and the protective film forming film 13 are provided with a release film 14 . The adhesive layer 12 which is in contact with the film 13 for forming a protective film contains the layer of the alkyl (meth) acrylate copolymer described above, and the alkyl (meth) acrylate copolymer has an alkyl group constituting the alkyl ester. The structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more.

In the composite sheet 1 for forming a protective film, the adhesive layer 12 is laminated on the surface 11a of the substrate 11, and the protective film forming film 13 is laminated on a part of the surface 12a of the adhesive layer 12. In the surface 12a of the adhesive layer 12, the exposed surface of the film for forming a protective film 13 and the surface 13a (upper surface and side surface) of the film 13 for forming a protective film are laminated with a release film 14.

Further, a void portion may be present between the release film 14 and the surface 12a of the adhesive layer 12 or the surface 13a of the protective film formation film 13. For example, insurance A region indicated by reference numeral 130a (a region on the side of the adhesive layer 12) and a region indicated by a reference numeral 120a in the surface 12a of the adhesive layer 12 on the surface 13a of the film for forming a film 13 (film for forming a protective film 13) The gap portion is easily formed between the side region and the release film 14. In other words, a region in the vicinity of the boundary between the film for forming the protective film 13 and the adhesive layer 12 and in contact with the release film 14 is likely to generate a void portion.

In the composite sheet 1 for forming a protective film, the back surface of the semiconductor wafer (not shown) is attached to the surface 13a of the film for protective film formation 13 in a state in which the release film 14 is removed. The exposed surface of the surface 12a of the adhesive layer 12 on which the protective film forming film 13 is not laminated is attached to a jig such as a ring frame.

Fig. 2 is a cross-sectional view showing another embodiment of the composite sheet for forming a protective film of the present invention. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals as in FIG. 1, and detailed description thereof will be omitted. The same is true in the figure below in Figure 3.

In the composite sheet 2 for forming a protective film, the protective film forming film 23 is formed over the entire surface of the surface 12a of the adhesive layer 12, and a part of the surface 23a of the protective film forming film 23 is laminated with a jig. In the surface layer 23a of the protective film forming film 23, the exposed surface of the adhesive film forming layer 23 and the surface 15a (upper surface and side surface) of the adhesive adhesive layer 15 are laminated on the surface 23a of the protective film forming film 23, and a release film is laminated. 14. Other than this, it is the same as the composite sheet 1 for protective film formation shown in FIG. Adhesion to the film 23 for forming a protective film The agent layer 12 contains the aforementioned alkyl (meth) acrylate copolymer, and the alkyl (meth) acrylate copolymer has an alkyl (meth) acrylate having a carbon number of 8 or more from an alkyl group constituting the alkyl ester. a structural unit derived from a base ester.

In one aspect, the composite sheet for forming a protective film of the present invention comprises a substrate, an adhesive layer, a film for forming a protective film, an adhesive layer for a jig, and a release film; and the adhesive layer is laminated on the substrate; The film for forming a protective film is formed on the entire surface layer of the pressure-sensitive adhesive layer; the adhesive layer for a jig is laminated on a part of the surface of the film for forming a protective film; and the surface of the film for forming a protective film is not laminated. The exposed surface of the adhesive layer for a jig and the upper surface and the side surface of the adhesive layer for a jig are laminated with the release film; and the adhesive layer in contact with the film for forming a protective film contains the (meth)acrylic acid. The base ester copolymer, and the alkyl (meth)acrylate copolymer has a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more and 18 or less of an alkyl group constituting the alkyl ester.

The adhesive adhesive layer 15 may be, for example, a single layer structure containing an adhesive component, or may have a plurality of layer structures having a layer containing an adhesive component in a two-layer layer of a core material.

Further, a void portion may be present between the release film 14 and the surface 23a of the protective film forming film 23 or the surface 15a of the adhesive adhesive layer 15. For example, the region indicated by the reference numeral 150a (the region on the side of the protective film forming film 23) of the surface 15a of the adhesive adhesive layer 15 and the region indicated by the symbol 230a in the surface 23a of the protective film forming film 23 ( Binder adhesive layer 15 side The space between the region and the release film 14 is likely to occur.

In other words, in the vicinity of the boundary between the adhesive binder layer 15 and the protective film forming film 23, the void portion is likely to be generated in the region in contact with the release film 14.

In the composite sheet 2 for forming a protective film, the back surface of the semiconductor wafer (not shown) is attached to the surface 23a of the protective film forming film 23, and the composite film 2 is formed. The upper surface of the surface 15a of the adhesive adhesive layer 15 is attached to a jig such as a ring frame and used.

Fig. 3 is a cross-sectional view showing still another embodiment of the composite sheet for forming a protective film of the present invention.

The composite sheet 3 for forming a protective film shown here has a double-layered adhesive layer 32 instead of the adhesive layer 12, and the double-layered adhesive layer 32 sequentially laminates the first adhesive layer from the side of the substrate 11 The 321 and the second adhesive layer 322 are the same as the composite sheet 1 for forming a protective film shown in Fig. 1 .

When the composite film 3 for forming a protective film is viewed from the top, the area of the second adhesive layer 322 is the same as that of the film 13 for forming a protective film, and the peripheral portion is placed so as to overlap the film 13 for forming a protective film. The film 13 for forming a protective film is provided on the surface 32a (that is, the surface 322a of the second adhesive layer 322) on the side opposite to the substrate side of the adhesive layer 32. Further, the first adhesive layer 321 is provided so as to cover the entire surface of the surface 11a of the substrate 11, and the area of the first adhesive layer 321 is larger than that of the second adhesive layer 322 when viewed as described above.

In the composite sheet 3 for forming a protective film, the second adhesive layer 322 which is in contact with the film for forming a protective film 13 contains the alkyl (meth) acrylate copolymer, and the alkyl (meth) acrylate copolymer has A structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more constituting an alkyl group of an alkyl ester. In addition, the first adhesive layer 321 which is not in contact with the film for forming a protective film 13 may contain the alkyl (meth)acrylate copolymer or may not contain the alkyl (meth)acrylate copolymer.

In other words, the composite sheet for forming a protective film of the present invention comprises a substrate, a first adhesive layer, a second adhesive layer, a film for forming a protective film, an adhesive layer for a jig, and a release film; The adhesive layer is provided on the substrate so as to cover the upper surface of the substrate; the second adhesive layer is provided on the first adhesive layer; and the peripheral film portion and the second adhesive layer are formed on the protective film forming film. The superposition method is provided on the second adhesive layer, and the release film is laminated on the upper surface and the side surface of the protective film formation film, the side surface of the second adhesive layer, and the first adhesive layer. The surface of the second adhesive layer is the same as the film for forming a protective film when viewed from above, and the area of the first adhesive layer is larger than the second adhesive. The second adhesive layer contains the alkyl (meth)acrylate copolymer, and the alkyl (meth)acrylate copolymer has a carbon number of 8 or more and 18 or less from the alkyl group constituting the alkyl ester. Derived from alkyl (meth)acrylate Structural units.

Fig. 4 is a cross-sectional view showing still another embodiment of the composite sheet for forming a protective film of the present invention.

The composite sheet 4 for forming a protective film shown here has a double-layered adhesive layer 42 instead of the adhesive layer 12, and the double-layered adhesive layer 42 sequentially laminates the first adhesive layer from the side of the substrate 11 The 421 and the second adhesive layer 422 are the same as the composite sheet 2 for forming a protective film shown in Fig. 2 .

When the composite sheet 4 for forming a protective film is viewed from above, the area of either the first adhesive layer 421 and the second adhesive layer 422 is the same as that of the protective film forming film 23.

The film 23 for forming a protective film is provided on the surface 42a of the adhesive layer 42 (that is, the surface 422a of the second adhesive layer 422).

In the composite sheet 4 for forming a protective film, the second adhesive layer 422 which is in contact with the film for forming a protective film 23 contains the alkyl (meth) acrylate copolymer, and the alkyl (meth) acrylate copolymer has A structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more constituting an alkyl group of an alkyl ester. In addition, the first adhesive layer 421 which is not in contact with the film for forming a protective film 23 may contain the alkyl (meth)acrylate copolymer or may not contain the alkyl (meth)acrylate copolymer.

In other words, the composite sheet for forming a protective film of the present invention comprises a substrate, a first adhesive layer, a second adhesive layer, a film for forming a protective film, an adhesive layer for a jig, and a release film; The adhesive layer is laminated on the substrate; the second adhesive layer is laminated on the first adhesive layer; the protective film forming film is laminated on the second adhesive layer; and the protective film forming film is formed. Part of the surface is laminated with the aforementioned adhesive for the jig In the surface of the film for forming a protective film, the exposed surface of the adhesive layer for the jig and the upper surface and the side surface of the adhesive layer for the jig are laminated, and the release film is laminated; The first adhesive layer, the second adhesive layer 422, and the protective film forming film 23 have the same area in plan view, and the second adhesive layer that is in contact with the protective film forming film contains the above (methyl An alkyl acrylate copolymer, wherein the alkyl (meth) acrylate copolymer has a structural unit derived from an alkyl (meth) acrylate having a carbon number of 8 or more and 18 or less constituting an alkyl group of the alkyl ester; .

The composite sheet for forming a protective film of the present invention is not limited to those shown in Figs. 1 to 4, and may be a composite for forming a protective film shown in Figs. 1 to 4 within a range not impairing the effects of the present invention. A part of the sheet is composed of a modification or a deletion, or a composite sheet for forming a protective film described above is further added to another composition.

For example, in the composite sheet 3 for forming a protective film shown in FIG. 3, when the composite sheet 3 for forming a protective film is viewed in plan as viewed from above, the area of the second adhesive layer 322 is the same as that of the film 13 for forming a protective film. The area of the second adhesive layer 322 is smaller than the area of the protective film forming film 13, and may be larger than the area of the protective film forming film 13, for example, the second adhesive layer. The area of the agent layer 322 may be the same as that of the first adhesive layer 321.

In addition, in the composite sheet 3 for forming a protective film shown in FIG. 3 and the composite sheet 4 for forming a protective film shown in FIG. 4, the adhesive layers are both in a two-layer structure, but The adhesive layer may also be a laminated structure of three or more layers. In this case, among the three or more adhesive layers, the layer in contact with the film for forming a protective film (that is, the uppermost layer farthest from the substrate in the thickness direction of the adhesive layer) contains the aforementioned (meth)acrylic acid alkyl group. The ester copolymer may have the above-mentioned (meth)acrylic acid alkyl ester copolymer or may not contain the aforementioned alkyl (meth)acrylate copolymer.

As described in the following examples, the composite sheet for forming a protective film having a size of 25 mm × 150 mm has a peeling angle of 180°, a temperature of 23° C., and a tensile speed of 300 mm/min. The peeling force measured by the form of the load at the time of peeling from the protective film (hereinafter, referred to as "the peeling force before the adhesive layer is cured") is preferably 2000 mN/25 mm or more, and more preferably 2200 mN/25 mm or more.

Similarly, as described in the following examples, the composite sheet for forming a protective film having a size of 25 mm × 150 mm has a peeling angle of 180°, a temperature of 23° C., and a stretching speed of 300 mm/. The peeling force measured by the form of the load at the time of the peeling of the protective film (hereinafter, referred to as "the peeling force after the adhesive layer is cured") is preferably 2000 mN/25 mm or less, and may be, for example, 1700 mN/25 mm. Hereinafter, it is 1200 mN/25 mm or less, 700 mN/25 mm or less.

In the present invention, the composite sheet for forming a protective film having a size of 25 mm × 150 mm is a ratio of the peeling force before curing of the adhesive layer to the peeling force after curing of the adhesive layer ([peeling force before curing of the adhesive layer]/[ Adhesive The peeling force after curing of the agent layer is preferably 1.5 or more, and may be, for example, 3 or more, 6 or more, 12 or more.

<Method for Producing Composite Sheet for Forming Protective Film>

The composite sheet for forming a protective film of the present invention can be produced, for example, by forming an adhesive layer on the substrate from the above-mentioned adhesive composition, and forming a protective layer on the adhesive layer by the protective film forming composition. A film for film formation.

The adhesive layer can be formed by applying an adhesive composition to the surface of the substrate (the surface 11a of the substrate 11 in FIGS. 1 and 2) and drying. At this time, the applied adhesive composition may be heated as needed, thereby causing cross-linking. The heating conditions are preferably, for example, from 100 ° C to 130 ° C for from 1 minute to 5 minutes, but are not limited thereto. Alternatively, the adhesive layer may be formed by applying an adhesive composition to the surface of the release layer of the release material and drying the adhesive layer to the surface of the substrate, and then removing the aforementioned release material. .

The adhesive composition may be applied to the surface of the substrate or the surface of the release layer of the release material by a known method, and examples thereof include the following various coaters: an air knife coater and a knife coater. Bar coater, gravure coater, roll coater, roll coater, curtain coater, die coater, knife coater, screen coater, Meyer bar coater , contact coater, etc.

The film for forming a protective film can be formed by a method similar to the method of forming an adhesive layer on a substrate as described above, but it is generally difficult to directly apply a composition for forming a protective film on the adhesive layer. Therefore, it is preferable to form a film for forming a protective film by another method, and to bond the film for forming a protective film to the surface of the adhesive layer, for example, a protective film forming composition is applied to the surface of the release layer of the release material. The film for forming a protective film formed by drying and adhering to the surface of the adhesive layer, and then removing the above-mentioned release material or the like.

In addition, the composite sheet for forming a protective film of the present invention may be formed by forming an adhesive layer from the adhesive composition and forming a protective film from the protective film forming composition, for example, in the following manner. After the film is applied, the pressure-sensitive adhesive layer and the film for forming a protective film are laminated to form a laminate, and the surface of the pressure-sensitive adhesive layer of the laminate (the surface of the pressure-sensitive adhesive layer on which the film for forming a protective film is not provided) is attached. Combined with the substrate.

At this time, the conditions for forming the adhesive layer and the film for forming a protective film are the same as those of the above method.

For example, when the composite film for forming a protective film is viewed from above when viewed from above, when the surface area of the film for forming a protective film is smaller than that of the composite film for forming a protective film of the adhesive layer, the above-mentioned manufacturing is carried out. In the method, a film for forming a protective film which is previously cut into a specific size and shape may be provided on the adhesive layer.

<How to use a composite sheet for forming a protective film>

The method of using the composite sheet for forming a protective film of the present invention is as follows.

In other words, the back surface of the semiconductor wafer is attached to the film for forming a protective film of the composite sheet for forming a protective film, and the composite sheet for forming a protective film is fixed to the dicing apparatus.

Next, a film for forming a protective film is heated (for example, heated at 130 ° C for 2 hours) to be cured to form a protective film. In the case where the surface of the semiconductor wafer (electrode forming surface) is attached with a backside polishing tape, the back surface polishing tape is usually removed from the semiconductor wafer to form a protective film.

Next, the semiconductor wafer is diced to form a semiconductor wafer. During the formation of the protective film and during the dicing, the protective film may be irradiated with a laser beam from the substrate side of the composite sheet for forming a protective film, and printed on the surface of the protective film. At this time, as described above, since the peeling force of the adhesive layer and the protective film before curing is sufficiently large, even if gas is generated by laser printing, peeling of the adhesive layer and the protective film is suppressed, and gas is generated. The accumulation is suppressed. In addition, since the semiconductor wafer can be firmly and stably fixed to the composite sheet for forming a protective film, sputtering of the wafer or the like during dicing can be suppressed, and dicing can be performed stably. Further, in the case of performing laser printing, since the peeling of the adhesive layer and the protective film is suppressed as described above, and the generation of the gas volume is suppressed, the substrate and the adhesive layer can be clearly separated. The printing applied to the protective film was visually recognized.

Next, the adhesive layer is cured by irradiation with an active energy ray (for example, ultraviolet rays, electron beams, etc.), and the semiconductor wafer is peeled off together with the protective film attached to the back surface of the semiconductor wafer from the cured adhesive layer to be picked up. Thereby, a semiconductor wafer with a protective film is obtained. At this time, since the peeling force of the adhesive layer and the protective film after hardening is sufficiently small, the semiconductor wafer with the protective film can be picked up stably and easily, and cracking or chipping of the wafer at the time of picking up is suppressed.

For example, when the composite sheet 1 for forming a protective film shown in Fig. 1 is used, the back surface of the semiconductor wafer is attached to the film 13 for forming a protective film of the composite sheet 1 for forming a protective film, and the exposed adhesive layer 12 is attached. The composite sheet 1 for forming a protective film is attached to a cutting device by attaching it to a cutting jig (not shown) such as a ring frame. Then, after the protective film forming film 13 is cured to form a protective film, the film is cut, and then the active energy ray is irradiated to harden the region of the adhesive layer 12 other than the portion attached to the jig, and the pick-up is protected. The semiconductor wafer of the film can be used. When the composite sheet 1 for forming a protective film is used in this manner, it is necessary to adjust so that the specific region of the adhesive layer 12 is not cured, so that the composite sheet 1 for forming a protective film is prevented from being peeled off from the jig. On the other hand, when the composite sheet 1 for forming a protective film is used, it is not necessary to separately provide a structure for attaching the composite sheet 1 for forming a protective film to the jig.

On the other hand, when the composite sheet 2 for forming a protective film shown in Fig. 2 is used, a semi-conductive film is attached to the film 23 for forming a protective film of the composite sheet 2 for forming a protective film. The back surface of the bulk wafer is attached to a cutting jig (not shown) such as a ring frame by the adhesive layer 15 for the jig, and the composite film 2 for forming a protective film is fixed to the cutting device. Then, after the protective film forming film 23 is cured to form a protective film, the film is cut, and the adhesive layer 12 is cured by irradiating the active energy ray to pick up the semiconductor wafer with the protective film. When the composite sheet 2 for forming a protective film is used in this manner, unlike the case of using the composite sheet 1 for forming a protective film, it is not necessary to adjust so that the specific region of the adhesive layer 23 is not cured. On the other hand, unlike the composite sheet 1 for forming a protective film, the composite sheet 2 for forming a protective film must have the adhesive layer 15 for a jig. By providing the adhesive layer 15 for a jig, the adhesive layer 12 can be selected from a wide range of layers depending on the purpose.

As described above, the composite sheet for forming a protective film of the present invention is suitable for a sheet obtained by curing a film for forming a protective film to form a protective film, and then curing the adhesive layer, cutting the semiconductor wafer, and picking up the semiconductor wafer. The film for forming a protective film is completely or substantially completely cured. Further, the composite sheet for forming a protective film of the present invention exhibits an effect that the peeling force of the adhesive layer and the protective film remarkably changes before and after the adhesive layer is cured. This effect is caused by the fact that the adhesive layer contains a specific range of alkyl (meth) acrylate copolymer as an essential component.

In the above-mentioned composite film for forming a protective film described in the above-mentioned Japanese Patent Publication No. 2011-228450 (Patent Document 1), when the semiconductor wafer is picked up, the film for forming a protective film is stopped. Bonding the semiconductor wafer in an unhardened or partially hardened state When the sealing material is cured, the unhardened or partially hardened film for forming a protective film is simultaneously completely or substantially completely cured. That is, when the conventional composite film for forming a protective film is used, the characteristics of a film attached to the back surface of the wafer and the wafer at the stage of cutting the semiconductor wafer and picking up the semiconductor wafer are the same as those in the present invention. The film is completely different. Further, in this document, the composition of the adhesive layer and the film for forming a protective film which are suitable for curing the film for forming a protective film before cutting is not disclosed.

Another aspect of the composite sheet for forming a protective film of the present invention comprises a substrate, an adhesive layer, and a film for forming a protective film; the adhesive layer is laminated on the substrate, and the film for forming a protective film is laminated on the adhesive. The adhesive layer has active energy ray-curing property, and contains at least a (meth)acrylic acid alkyl ester copolymer in a layer in contact with the film for forming a protective film; the aforementioned (meth)acrylic acid alkyl ester copolymer The system has a copolymer of a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more and 18 or less, which constitutes an alkyl group of an alkyl ester; the film for forming a protective film has thermosetting property; The film-forming composite sheet was cut into a size of 25 mm × 150 mm, and then attached to a ruthenium wafer at 70 ° C. Then, the composite sheet for forming a protective film was heated at 130 ° C for 2 hours to form a film for forming a protective film. When the protective film is formed by curing, the peeling force of the adhesive layer before curing and the protective film at a peeling angle of 180°, a measurement temperature of 23° C., and a tensile speed of 300 mm/min (peeling force before curing of the adhesive layer) ) is 2000mN/2 5 mm or more, preferably 2300 mN/25 mm or more and 6300 mN/25 mm or less.

Furthermore, in the composite sheet for forming a protective film, when the composite sheet for forming a protective film is irradiated with ultraviolet rays under the conditions of an illuminance of 220 mW/cm ² and a light amount of 190 mJ/cm ^{2 to} cure the adhesive layer, the peeling angle is 180°. The peeling force of the adhesive layer after the curing and the protective film (the peeling force after the adhesive layer is cured) is 2000 mN/25 mm or less, preferably 500 mN, under the conditions of a temperature of 23 ° C and a tensile speed of 300 mm/min. /25mm or more, 1500mN/25mm or less.

Another aspect of the composite sheet for forming a protective film of the present invention comprises a substrate, an adhesive layer, and a film for forming a protective film; the adhesive layer is laminated on the substrate, and the film for forming a protective film is laminated on the adhesive. The layer of the adhesive layer has active energy ray-curing property, and at least the layer in contact with the film for forming a protective film contains an alkyl (meth) acrylate copolymer, and the alkyl (meth) acrylate copolymer contains a (meth)acrylic acid alkyl ester copolymer, an isocyanate crosslinking agent, a photopolymerization initiator, a solvent, and other components as needed; the aforementioned (meth)acrylic acid alkyl ester copolymer has a constituent alkyl ester a copolymer of a structural unit derived from an alkyl (meth)acrylate having a carbon number of 8 or more and 18 or less, preferably selected from the group consisting of 2-ethylhexyl acrylate, lauryl methacrylate, and acrylic acid. At least one of the group consisting of stearyl esters; the content of the structural unit derived from the alkyl (meth) acrylate having a carbon number of 8 or more of the alkyl group described above relative to the constituting the aforementioned (meth) acrylate The entire structure of the base copolymer The total mass of the film is 30% by mass or more and 100% by mass or less, preferably 35% by mass to 85% by mass or less, more preferably 40% by mass to 80% by mass or less, and the film for forming a protective film has thermosetting property. And contains polymer component (A), thermosetting a component (B), a hardening accelerator (C), and optionally selected from the group consisting of a solvent, a filler (D), a coupling agent (E), a crosslinking agent (F), and a general additive (G). At least one of the polymer components (A) is preferably selected from the group consisting of acrylic resins, polyesters, polyurethanes, urethane acrylate resins, polyoxyxylene resins, rubber-based polymers, and phenoxy groups. At least one of the group consisting of resins is more preferably an acrylic polymer; the thermosetting component (B) is preferably an epoxy resin (B11) and a heat hardener (B12), more preferably selected from the group consisting of Functional epoxy resin, biphenyl compound, bisphenol A diglycidyl ether and its hydride, o-cresol novolac epoxy resin, dicyclopentadiene epoxy resin, biphenyl epoxy resin, bisphenol At least one selected from the group consisting of a type A epoxy resin, a bisphenol F type epoxy resin, a phenylene skeleton type epoxy resin, and a bifunctional or higher epoxy compound, and is selected from the group consisting of strontium salts and binary At least one of the group consisting of acid oxime, dicyandiamide, and an amine adduct of a hardener, and more preferably selected from the group consisting of bisphenol A type epoxy trees And at least one of the group consisting of dicyclopentadiene type epoxy resins, and dicyandiamide; the hardening accelerator (C) is preferably 2-phenyl-4,5-dihydroxymethylimidazole After the composite sheet for forming a protective film was cut into a size of 25 mm × 150 mm, it was attached to a ruthenium wafer at 70 ° C, and then the composite sheet for forming a protective film was heated at 130 ° C for 2 hours to protect the above. When the film for film formation is cured to form a protective film, the peeling force of the adhesive layer before the curing and the protective film (adhesive layer) at a peeling angle of 180°, a measurement temperature of 23° C., and a tensile speed of 300 mm/min The peeling force before hardening is 2000 mN/25 mm or more, preferably 2300 mN/25 mm or more and 6300 mN/25 mm or less.

Furthermore, in the composite sheet for forming a protective film, when the composite sheet for forming a protective film is irradiated with ultraviolet rays under the conditions of an illuminance of 220 mW/cm ² and a light amount of 190 mJ/cm ^{2 to} cure the adhesive layer, the peeling angle is 180°. The peeling force of the adhesive layer after the curing and the protective film (the peeling force after the adhesive layer is cured) is 2000 mN/25 mm or less, preferably 500 mN, under the conditions of a temperature of 23 ° C and a tensile speed of 300 mm/min. /25mm or more, 1500mN/25mm or less.

Another aspect of the present invention is the use of the composite sheet for forming a protective film for producing a semiconductor wafer with a protective film; the composite sheet for forming a protective film comprising a substrate, an adhesive layer, and a protective film. a film; the adhesive layer is laminated on the substrate; the protective film forming film is laminated on the adhesive layer; and the adhesive layer has active energy ray curability and is in contact with at least the protective film forming film. The layer contains an alkyl (meth)acrylate copolymer; the alkyl (meth)acrylate copolymer has an alkyl (meth)acrylate having a carbon number of 8 or more and 18 or less from an alkyl group constituting the alkyl ester. a copolymer of a structural unit derived from a base; the film for forming a protective film has thermosetting property; and the composite sheet for forming a protective film is cut into a size of 25 mm × 150 mm, and then attached to a silicon wafer at 70 ° C, Then, the composite sheet for forming a protective film was heated at 130 ° C for 2 hours, and when the film for forming a protective film was cured to form a protective film, the peeling angle was 180°, the measurement temperature was 23° C., and the stretching speed was 300 mm/min. , The adhesive force of the peeling layer and the protective film prior to curing (hardening adhesive agent layer before the peeling force) of 2000mN / 25mm or more, preferably 2300mN / 25mm or more, 6300mN / 25mm or less.

Furthermore, in the composite sheet for forming a protective film, when the composite sheet for forming a protective film is irradiated with ultraviolet rays under the conditions of an illuminance of 220 mW/cm ² and a light amount of 190 mJ/cm ^{2 to} cure the adhesive layer, the peeling angle is 180°. The peeling force of the adhesive layer after the curing and the protective film (the peeling force after the adhesive layer is cured) is 2000 mN/25 mm or less, preferably 500 mN, under the conditions of a temperature of 23 ° C and a tensile speed of 300 mm/min. /25mm or more, 1500mN/25mm or less.

A method of manufacturing a semiconductor wafer with a protective film, comprising the steps of: attaching a protective film forming composite sheet to a back surface of a semiconductor wafer by a film for forming a protective film; and attaching the foregoing by heating The protective film forming film in the composite sheet for forming a protective film is cured to form a protective film; the semiconductor wafer on which the protective film is formed is cut to form a semiconductor wafer; and the protective film is formed by irradiating an active energy ray. The adhesive layer in the composite sheet is hardened, and then the semiconductor wafer is picked up together with the protective film attached to the back surface of the semiconductor wafer; and the composite sheet for forming a protective film comprises a substrate, the adhesive layer, and In the film for forming a protective film, the adhesive layer is laminated on the substrate, the film for forming a protective film is laminated on the adhesive layer, and the adhesive layer has active energy ray curability and at least the protective film. The layer formed in contact with the film contains an alkyl (meth)acrylate copolymer; the aforementioned alkyl (meth)acrylate copolymer A copolymer having a structural unit derived from an alkyl (meth)acrylate having an alkyl group of an alkyl ester of 8 or more and 18 or less; and the film for forming a protective film has thermosetting property.

[Examples]

Hereinafter, the present invention will be described in more detail by way of specific examples. However, the present invention is not limited by the examples shown below.

[Example 1]

<Manufacture of composite sheet for forming a protective film>

A composite sheet for forming a protective film having the structure shown in Fig. 1 was produced. More specifically, it is as follows.

[Production of support sheet (formation of adhesive layer)]

The adhesive composition was applied onto one surface of a polypropylene film (thickness: 80 μm, manufactured by Mitsubishi Plastics Co., Ltd.) as a substrate and dried to form an ultraviolet curable adhesive layer (thickness: 10 μm) to obtain a support sheet. The above-mentioned adhesive composition is a composition containing 100 parts by mass of a (meth)acrylic acid alkyl ester copolymer (solid content) and a trifunctional phthalic diisocyanate crosslinking agent (Mitsui Takeda Chemicals, Inc.). Manufactured "Takenate D110N") 6.6 parts by mass (solid content) and photopolymerization initiator ("Irgacure 127" manufactured by BASF Corporation) 3.0 parts by mass (solid content), and methyl ethyl ketone, toluene was used. A mixed solvent of ethyl acetate and a composition in which the solid content concentration was adjusted to 30% by mass. Further, the alkyl (meth) acrylate copolymer is an ultraviolet curable acrylic copolymer having a weight average molecular weight of 1,100,000 obtained by the following method: 2-ethylhexyl acrylate (hereinafter sometimes referred to as a short name) "2EHA") 80 parts by mass, acrylic acid-2-hydroxy Ethyl ester (hereinafter sometimes abbreviated as "HEA") 20 parts by mass of a prepolymer obtained by copolymerization, further with 2-methylpropenyloxyethyl isocyanate (-2-isocyanatoethyl methacrylate) 21.4 parts by mass of the ester (hereinafter, abbreviated as "MOI") (the total number of moles of the isocyanate group in the 2-methacryloxyethyl isocyanate is 0.8 times the total number of moles of the hydroxyl group in the HEA. The amount is carried out. The amount of the monomer component when the (meth)acrylic acid alkyl ester copolymer was produced is shown in Table 1. In addition, in Table 1, the column of a monomer component is described as "-", and it shows that this monomer component was not mix|blended.

[Manufacture of Composite Sheet for Forming Protective Film (Formation of Film for Forming Protective Film)]

The release treatment surface coating of a release film ("SP-PET381031" manufactured by Lintec Corporation, thickness: 38 μm) which was subjected to a release treatment by polyfluorination treatment on one side of a polyethylene terephthalate film was coated. The composition for forming a protective film was dried and formed into a film for forming a protective film (thickness: 25 μm). The protective film-forming composition is a composition obtained by mixing the following components in an amount (solid content) shown in Table 2, and using a mixed solvent of methyl ethyl ketone, toluene, and ethyl acetate to form a solid matter. The composition whose concentration of the component was adjusted to 55% by mass.

Then, the film for forming a protective film is bonded to the surface of the adhesive layer of the support sheet obtained above to obtain a composite sheet for forming a protective film, and the composite sheet for forming a protective film is formed into a film for forming a protective film. The surface opposite to the side on which the adhesive layer is provided is provided with the above-mentioned release film.

(polymer component (A))

(A)-1: an acrylic polymer obtained by copolymerizing 85 parts by mass of methyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate (weight average molecular weight: 370,000, glass transition temperature: 6 ° C)

(thermosetting component (B))

‧Epoxy resin (B11)

(B11)-1: Bisphenol A type epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 184g/eq to 194g/eq)

(B11)-2: Bisphenol A type epoxy resin ("jER1055" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 800g/eq to 900g/eq)

(B11)-3: Dicyclopentadiene type epoxy resin ("Epiclon HP-7200HH" manufactured by DIC Corporation, epoxy equivalent 255g/eq to 260g/eq)

‧Hot hardener (B12)

(B12)-1: dicyandiamide (solid dispersion type latent curing agent, "Adeka Hardener EH-3636AS" manufactured by ADEKA Corporation, active hydrogen amount 21 g/eq)

(hardening accelerator (C))

(C)-1: 2-phenyl-4,5-dihydroxymethylimidazole ("Curezol 2PHZ" manufactured by Shikoku Kasei Kogyo Co., Ltd.)

(filling material (D))

(D)-1: cerium oxide filler ("SC2050MA" of Admatechs, average particle size 0.5 μm)

(coupler (E))

(E)-1: decane coupling agent ("A-1110" manufactured by Uny Corporation of Japan)

(General additive (G))

(G)-1: carbon black (colorant, "#MA650" manufactured by Mitsubishi Chemical Corporation, average particle size 28 nm)

<Evaluation of composite sheet for forming a protective film>

[Suppression of wafer spatter during cutting]

After removing the release film from the composite sheet for forming a protective film obtained as described above, the exposed film for forming a protective film is attached to a dry polishing surface of a silicon wafer (diameter: 6 Å, thickness: 100 μm) at 70 ° C, and The exposed adhesive layer was attached to the ring frame and allowed to stand for 30 minutes.

Then, the composite sheet for forming a protective film was heated at 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film.

Next, using a dicing apparatus, the ruthenium wafer was cut into a size of 5 mm × 5 mm to obtain a wafer. At this time, it was visually confirmed whether or not the wafer was splashed, and the case where no wafer was splashed was evaluated as "A", and the case where one or more wafers were splashed was evaluated as "B". The results are shown in Table 3.

[pickup]

After removing the release film from the composite sheet for forming a protective film obtained as described above, the exposed film for forming a protective film was attached to a dry polishing surface of a tantalum wafer (diameter: 6 Å, thickness: 100 μm) at 70 ° C, and The exposed adhesive layer was attached to the ring frame and allowed to stand for 30 minutes.

Then, the composite sheet for forming a protective film was heated at 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film.

Next, using a dicing apparatus, the ruthenium wafer was cut into a size of 5 mm × 5 mm to obtain a wafer. Then, using an ultraviolet irradiation apparatus (manufactured by the Lintec Corporation "RAD2000m / 8"), at / cm illumination conditions 220mW / cm ^2, light quantity of 190mJ ² with a high pressure mercury lamp using the composite sheet is irradiated on the protective film is formed as from the substrate side of the light source Ultraviolet rays harden the adhesive layer.

Next, 20 wafers were picked up using a die bonder ("BESTEM-D02" manufactured by Canon Machinery Inc.), and the case where no wafer was cracked or notched was evaluated as "A", and more than one wafer was cracked or The case of the gap was evaluated as "B". The results are shown in Table 3.

[Removal force of adhesive layer and protective film before hardening]

After the composite sheet for forming a protective film obtained in the above-mentioned manner was cut into a size of 25 mm × 150 mm, the release film was removed, and the exposed film for forming a protective film was formed using a laminator ("LAMIPACKER LPD3214" manufactured by Fuji Co., Ltd.). It is attached to a dry polished surface of a silicon wafer (6 直径 in diameter and 500 μm in thickness) at 70 °C.

Then, the composite sheet for forming a protective film was heated at 130 ° C for 2 hours to cure the film for forming a protective film to form a protective film, thereby preparing a test piece (1).

The test piece (1) was subjected to a tensile test using a precision universal testing machine ("Autograph AG-IS" manufactured by Shimadzu Corporation) at a peeling angle of 180°, a measuring temperature of 23° C., and a tensile speed of 300 mm/min. The support sheet (the layer of the adhesive layer before curing and the substrate) is peeled off from the protective film, and the load at this time is measured, and the peeling force of the adhesive layer and the protective film before curing (adhesive layer peeling force before curing) Furthermore, as the measured value of the aforementioned load In the measured values when the support sheet was peeled by 100 mm, the measured values excluding the effective values were excluded from the initial peeling length of 10 mm and the final peeling length of 10 mm.

The results are shown in Table 3. The value of "Before the adhesive layer is hardened" in the column of "peeling force (mN/25mm)" in Table 3 is the corresponding result.

[Removal force of adhesive layer and protective film after hardening]

A test piece (1) identical to the above was produced.

Next, an ultraviolet irradiation device (manufactured by the Lintec Corporation "RAD2000m / 8"), at / cm illumination conditions 220mW / cm ^2, light quantity of 190mJ ² with a high pressure mercury lamp using the composite sheet is irradiated on the protective film is formed as from the substrate side of the light source Ultraviolet rays harden the adhesive layer to prepare a test piece (2).

The test piece (2) was subjected to a tensile test in the same manner as in the above test piece (1), that is, the support sheet (the layered body of the adhesive layer after curing and the substrate) was peeled off from the protective film as a cured film. The peeling force of the adhesive layer and the protective film (adhesive layer peeling force after hardening). The results are shown in Table 3. The value of "after the adhesive layer is hardened" in the column of "peeling force (mN/25mm)" in Table 3 is the corresponding result.

<Manufacture and Evaluation of Composite Sheet for Forming Protective Film>

[Embodiment 2]

When the adhesive layer is formed, an ultraviolet curable acrylic copolymer having a weight average molecular weight of 500,000 is used instead of the above-mentioned weight average molecular weight of 1,100,000 as an alkyl (meth)acrylate copolymer, and A composite sheet for forming a protective film was produced and evaluated in the same manner as in Example 1, wherein the ultraviolet curable acrylic copolymer having a weight average molecular weight of 500,000 was obtained in the following manner: as shown in Table 1, 40 parts by mass of 2EHA was used. 40 parts by mass of vinyl acetate (hereinafter sometimes abbreviated as "VAc"), and a prepolymer obtained by copolymerization of 20 parts by mass of HEA, further 21.4 parts by mass with MOI (total molar number of isocyanate groups in MOI) The reaction was carried out in an amount of 0.8 times the total number of moles of the hydroxyl group in the HEA. The results are shown in Table 3.

[Example 3]

When the adhesive layer is formed, the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is used in place of the above-mentioned weight average molecular weight of 1,100,000 as the alkyl (meth)acrylate copolymer, and otherwise the same as in the first embodiment. In the method of producing and evaluating a composite sheet for forming a protective film, the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is obtained as follows: as shown in Table 1, a lauryl methacrylate is used (hereinafter, For example, "LMA" is 80 parts by mass, and 20 parts by mass of HEA is copolymerized to obtain a pre-copolymer, further 21.4 parts by mass with MOI (the total number of moles of isocyanate groups in MOI is the total number of hydroxyl groups in HEA) The reaction was carried out in an amount of 0.8 times the number of ears. The results are shown in Table 3.

[Example 4]

When the adhesive layer is formed, an ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is used instead of the above-mentioned weight average molecular weight of 1,100,000 as the alkyl (meth)acrylate copolymer, and A composite sheet for forming a protective film was produced and evaluated in the same manner as in Example 1, wherein the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 was obtained in the following manner: as shown in Table 1, an isostearyl acrylate was used. 80 parts by mass of a base ester (hereinafter sometimes abbreviated as "ISTA") and a prepolymer obtained by copolymerization of 20 parts by mass of HEA, further 21.4 parts by mass with MOI (the total number of moles of isocyanate groups in MOI is HEA) The reaction is carried out in an amount of 0.8 times the total number of moles of the hydroxyl group in the medium. The results are shown in Table 3.

[Comparative Example 1]

When the adhesive layer is formed, the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is used in place of the above-mentioned weight average molecular weight of 1,100,000 as the alkyl (meth)acrylate copolymer, and otherwise the same as in the first embodiment. In the method of producing and evaluating a composite sheet for forming a protective film, the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is obtained as follows: as shown in Table 1, butyl acrylate (hereinafter sometimes referred to as a short name) is used. 40 parts by mass of "BA"), 40 parts by mass of VAc, and 20 parts by mass of HEA, and further obtained with 21.4 parts by mass of MOI (the total number of moles of isocyanate groups in MOI is hydroxyl group in HEA) The reaction was carried out in an amount of 0.8 times the total molar amount. The results are shown in Table 3.

[Comparative Example 2]

When the adhesive layer is formed, an ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 is used instead of the above-mentioned weight average molecular weight of 1,100,000 as the alkyl (meth)acrylate copolymer, and A composite sheet for forming a protective film was produced and evaluated in the same manner as in Example 1, wherein the ultraviolet curable acrylic copolymer having a weight average molecular weight of 600,000 was obtained in the following manner: as shown in Table 1, 40 parts by mass of BA was used. 40 parts by mass of methyl methacrylate (hereinafter sometimes abbreviated as "MMA"), and a prepolymer obtained by copolymerization of 20 parts by mass of HEA, further 21.4 parts by mass with MOI (the total amount of isocyanate groups in MOI) The reaction was carried out in an amount in which the number of ears was 0.8 times the total number of moles of the hydroxyl group in the HEA. The results are shown in Table 3.

[Table 2]

When the composite sheet for forming a protective film of Examples 1 to 4 is used, in the sheet, the alkyl (meth)acrylate copolymer has a carbon number of 8 or more from the alkyl group constituting the alkyl ester (A) a structural unit derived from an alkyl acrylate, whereby the peeling force of the adhesive layer and the protective film before hardening is sufficiently large, the cutting can be performed stably, and the adhesive layer and the protective film are peeled off after hardening. The force is small enough to pick up the semiconductor wafer stably.

The ratio of the peeling force before and after curing of the adhesive layer ([peeling force before curing of the adhesive layer] / [peeling force after curing of the adhesive layer]) is 4.6 in the first embodiment and 4.2 in the second embodiment, and the third embodiment It is 14.3 in the middle, 1.8 in the embodiment 4, and particularly large in the examples 1 to 3. In the embodiment 3, it is obviously larger, and it is indicated that the carbon number of the alkyl group constituting the alkyl ester is about 12 and 12 or so. The value of the present invention is particularly high.

On the other hand, when the composite sheet for forming a protective film of Comparative Example 1 to Comparative Example 2 is used, the alkyl (meth) acrylate copolymer does not have the carbon number of the alkyl group constituting the alkyl ester. a structural unit derived from an alkyl (meth) acrylate of 8 or more, whereby the peeling force of the adhesive layer and the protective film before curing is sufficiently large to stably perform cutting, but the adhesive layer and the protective film after curing The peeling force does not become sufficiently small to stably pick up the semiconductor wafer.

(industry availability)

The present invention can be utilized in the manufacture of a semiconductor wafer or the like protected by a protective film on the back surface, and thus is extremely useful industrially.

1‧‧‧Composite film for protective film formation

10‧‧‧Support tablets

11‧‧‧Substrate

11a‧‧‧ Surface of the substrate

12‧‧‧Adhesive layer

12a‧‧‧ Surface of the adhesive layer

120a‧‧‧A film-side area for protective film formation

13‧‧‧film for protective film formation

13a‧‧‧Surface of film for protective film formation

130a‧‧‧A region on the adhesive layer side

14‧‧‧Release film

Claims (3)

A composite sheet for forming a protective film, comprising an adhesive layer on a substrate, a film for forming a protective film on the adhesive layer, the adhesive layer having active energy ray curability, and the film for forming a protective film having heat The composite sheet for forming a protective film is used for producing a semiconductor wafer with a protective film, and the protective film forming film is attached to the back surface of the semiconductor wafer by the film for forming a protective film, and is heated by heating. After the film for forming a protective film is cured as a protective film, and then the semiconductor wafer is diced to form a semiconductor wafer, the adhesive layer is cured by irradiating an active energy ray, and then the semiconductor wafer is attached to the semiconductor. The protective film on the back surface of the wafer is picked up together, thereby manufacturing a semiconductor wafer with a protective film; the adhesive layer contains an alkyl (meth)acrylate copolymer in at least a layer in contact with the film for forming a protective film; The (meth)acrylic acid alkyl ester copolymer has an alkyl (meth) acrylate having a carbon number of 8 or more from an alkyl group constituting the alkyl ester. a structural unit derived from a base ester. The composite sheet for forming a protective film according to claim 1, wherein the film for forming a protective film contains an epoxy resin, a thermosetting agent, and an imidazole, and the thermosetting agent is dissolved by heating and hardened to the epoxy resin. active. The composite sheet for forming a protective film according to claim 1 or 2, wherein The alkyl group of the above alkyl ester has a carbon number of 11 to 18.