JP2020017758A - Composite sheet for forming protective film - Google Patents

Abstract

To provide a composite sheet for forming a protective film including a backing material, an adhesive layer and a film for forming a protective film, and forming a protective film on the reverse face of a semiconductor chip, in which the peel force of the protective film and the film for forming the protective film or of the protective film after hardening is sufficiently large before hardening of the adhesive layer, and sufficiently small after hardening of the adhesive layer.SOLUTION: A composite sheet 1 for forming a protective film includes a backing material 11, an adhesive layer 12 having active energy beam curability, and a thermosetting film 13 for forming a protective film. The adhesive layer 12 contains a specific (meth) acrylic acid alkyl ester copolymer, at least in a layer in contact with the film 13 for forming a protective film, and the adhesive layer 12 contains, as a photoinitiator, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methyl-propionyl)-benzyl) phenyl)-2-methyl-propane-1-on).SELECTED DRAWING: Figure 1

Description

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 chip.
Priority is claimed on Japanese Patent Application No. 2015-114714 filed on June 5, 2015, the content of which is incorporated herein by reference.

  2. Description of the Related Art In recent years, semiconductor devices have been manufactured using a mounting method called a so-called face down method. In the face-down method, a semiconductor chip having electrodes such as bumps on a circuit surface is used, and the electrodes are bonded to a substrate. For this reason, the back surface opposite to the circuit surface of the chip may be exposed.

  A resin film made of an organic material is formed as a protective film on the exposed back surface of the chip, and may be taken into a semiconductor device as a semiconductor chip with a protective film. The protective film is used to prevent cracks from occurring in the chip after the dicing step or packaging, or to bond the obtained chip to another member such as a die pad portion or another semiconductor chip. .

  On the other hand, a composite sheet for forming a protective film, comprising a pressure-sensitive adhesive layer on a base material and a film for forming a protective film on the pressure-sensitive adhesive layer, is used for forming such a protective film. The composite sheet for forming a protective film is such that, in addition to the protective film-forming film having a protective film forming ability, a laminated structure of a base material and an adhesive layer functions as a dicing sheet. It can be said that the forming film and the dicing sheet are integrated.

  Such a composite sheet for forming a protective film is used, for example, as follows. That is, after the protective film forming composite sheet is attached to the back surface (the surface opposite to the electrode forming surface) of the semiconductor wafer by the protective film forming film, the semiconductor wafer is formed into semiconductor chips by dicing. Next, the adhesive layer is cured by irradiation with active energy rays, and the semiconductor chip is separated from the adhesive layer and picked up. On the other hand, the protective film forming film is picked up together with the semiconductor chip, and finally exists on the back surface of the semiconductor chip in a state of a hardened protective film. As such a protective sheet forming composite sheet, the protective film forming film is uncured or partially cured when the semiconductor chip is picked up, and the semiconductor chip is bonded and sealed with a sealing material. Japanese Patent Application Laid-Open No. H11-163,086 discloses a technique in which the uncured or partially cured protective film forming film is completely or almost completely cured at the same time as curing.

JP 2011-228450 A

  However, the conventional protective film forming composite sheet as disclosed in Patent Document 1, depending on the use conditions, the peeling force between the pressure-sensitive adhesive layer and the protective film forming film, especially after the pressure-sensitive adhesive layer is cured. If it is too large, there is a problem that the chip may be cracked or chipped when picking up the semiconductor chip.

  The present invention has been made in view of the above circumstances, comprises an adhesive layer on a base material, comprising a protective film forming film on the adhesive layer, forming a protective film on the back surface of the semiconductor chip The protective sheet is a composite sheet for forming a protective film, the peeling force between the pressure-sensitive adhesive layer and the protective film-forming film or the protective film after the curing is sufficiently large before the pressure-sensitive adhesive layer is cured, and the dicing is stable. An object of the present invention is to provide a composite film for forming a protective film, which is sufficiently small after the pressure-sensitive adhesive layer is cured, and can stably pick up a semiconductor chip.

In order to solve the above problems, the present invention comprises an adhesive layer on a substrate, a protective film forming film on the adhesive layer, the adhesive layer has an active energy ray curable The protective film forming film is a protective film forming composite sheet having thermosetting properties, and the protective film forming composite sheet is attached to the back surface of the semiconductor wafer by the protective film forming film, The protective film forming film is cured by heating to form a protective film, and then the semiconductor wafer is diced into semiconductor chips, and then the pressure-sensitive adhesive layer is cured by irradiation with active energy rays. Is picked up together with the protective film affixed to the rear surface thereof, thereby producing a semiconductor chip with a protective film. At least the layer in contact with the protective film-forming film contains a (meth) acrylic acid alkyl ester copolymer, and the (meth) acrylic acid alkyl ester copolymer has an alkyl group constituting an alkyl ester. Has a constitutional unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms, and the pressure-sensitive adhesive layer has 2-hydroxyl-1- {4- [4- (2 -Hydroxy-2-methyl-propionyl) -benzyl] phenyl {-2-methyl-propan-1-one ".

In the composite sheet for forming a protective film of the present invention, the film for forming a protective film comprises an epoxy resin, a thermosetting agent which is dissolved by heating and has a curing activity for the epoxy resin, and an imidazole. It is preferred to contain.
In the composite sheet for forming a protective film of the present invention, the alkyl group constituting the alkyl ester preferably has 11 to 18 carbon atoms.
That is, the present invention includes the following aspects.
[1] A pressure-sensitive adhesive layer is provided on a base material, and a protective film-forming film is provided on the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer has active energy ray curability, and the protective film-forming film is A protective film forming composite sheet having thermosetting properties,
After the protective film forming composite sheet is attached to the back surface of the semiconductor wafer with the protective film forming film, the protective film forming film is cured by heating to form a protective film, and then the semiconductor wafer is diced. After forming a semiconductor chip, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays, and then the semiconductor chip is picked up together with the protective film attached to the back surface of the semiconductor chip, thereby manufacturing a semiconductor chip with a protective film. Is used to
The pressure-sensitive adhesive layer contains a (meth) alkyl acrylate copolymer at least in a layer in contact with the protective film-forming film,
The (meth) acrylic acid alkyl ester copolymer has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in an alkyl group constituting the alkyl ester,
When the pressure-sensitive adhesive layer is used as a photopolymerization initiator, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one is used. And a composite sheet for forming a protective film.
[2] The film according to [1], wherein the protective film-forming film contains an epoxy resin, a thermosetting agent which is dissolved by heating and has a curing activity for the epoxy resin, and an imidazole. A composite sheet for forming a protective film.
[3] The composite sheet for forming a protective film according to [1] or [2], wherein the alkyl group constituting the alkyl ester has 11 to 18 carbon atoms.

  According to the present invention, a composite sheet for forming a protective film for forming a protective film on the back surface of a semiconductor chip, comprising a pressure-sensitive adhesive layer on a substrate and a film for forming a protective film on the pressure-sensitive adhesive layer And a peeling force between the pressure-sensitive adhesive layer and the protective film-forming film or the protective film after curing of the protective film-forming film (that is, a protective film that is a cured product of the protective film-forming film). However, before the pressure-sensitive adhesive layer is hardened, the dicing can be performed stably, and after the pressure-sensitive adhesive layer is hardened, the dicing is sufficiently small, and the semiconductor chip can be stably picked up. A composite sheet for forming a protective film is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically one Embodiment of the composite sheet for protective film formation which concerns on this invention. It is sectional drawing which shows typically another embodiment of the composite sheet for protective film formation which concerns on this invention. It is sectional drawing which shows typically further another embodiment of the composite sheet for protective film formation which concerns on this invention. It is sectional drawing which shows typically further another embodiment of the composite sheet for protective film formation which concerns on this invention.

<< Composite sheet for forming protective film >>
The protective film-forming composite sheet according to the present invention includes an adhesive layer on a substrate, and a protective film-forming film on the adhesive layer, and the adhesive layer has an active energy ray-curable property. The film for forming a protective film is a composite sheet for forming a protective film having thermosetting properties, and the composite sheet for forming a protective film is formed by attaching the protective sheet to the back surface of a semiconductor wafer using the film for forming a protective film. Curing the protective film forming film by heating to form a protective film, then dicing the semiconductor wafer into semiconductor chips, and then curing the pressure-sensitive adhesive layer by irradiation with active energy rays; By picking up the chip together with the protective film attached to the back surface thereof, it is used for manufacturing a semiconductor chip with a protective film, wherein the pressure-sensitive adhesive layer is At least the layer in contact with the protective film-forming film contains a (meth) acrylic acid alkyl ester copolymer, and the (meth) acrylic acid alkyl ester copolymer has an alkyl group constituting an alkyl ester. It has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms.
That is, one side of the composite sheet for forming a protective film according to the present invention includes:
A substrate, a pressure-sensitive adhesive layer, a protective film forming composite sheet including a protective film forming film,
The pressure-sensitive adhesive layer is laminated on the base material, and the protective film forming film is laminated on the pressure-sensitive adhesive layer;
The pressure-sensitive adhesive layer,
Has active energy ray curability,
At least a layer in contact with the protective film forming film contains a (meth) acrylic acid alkyl ester copolymer,
The alkyl (meth) acrylate copolymer is a copolymer having a constitutional unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in an alkyl group constituting the alkyl ester;
The protective film-forming film has thermosetting properties;
Affixing the protective film forming composite sheet to the back surface of the semiconductor wafer by the protective film forming film,
The protective film forming film in the attached protective film forming composite sheet is cured by heating to form a protective film,
Dicing the semiconductor wafer on which the protective film is formed into semiconductor chips, and after curing the adhesive layer by irradiation with active energy rays, together with the protective film attached to the back surface of the semiconductor chip, Picking up the semiconductor chip, for manufacturing a semiconductor chip with a protective film including,
It is a composite sheet for forming a protective film. In addition, in this specification, the laminated structure of the base material and the pressure-sensitive adhesive layer may be referred to as a “support sheet”. Further, in the protective film-forming composite sheet, the protective film-forming film may be cured by heating to form a protective film, or the composite sheet obtained by curing the pressure-sensitive adhesive layer by irradiation with active energy rays. As long as the laminated structure of the base material, the pressure-sensitive adhesive layer or its cured product, and the protective film is maintained, the composite sheet is referred to as a protective film-forming composite sheet.

  In the composite sheet for forming a protective film according to the present invention, the layer of the pressure-sensitive adhesive layer which is in contact with the film for forming a protective film contains the (meth) acrylic acid alkyl ester copolymer in a specific range as described above. By this, before the pressure-sensitive adhesive layer is cured, the peeling force between the pressure-sensitive adhesive layer and the cured protective film forming film (that is, the protective film) is sufficiently large, and the semiconductor wafer can be firmly and stably fixed. Therefore, chip jumping or the like during dicing of the semiconductor wafer is suppressed, and dicing can be performed stably.

  In the case where the protective film forming composite sheet is used, in a state where the protective film is adhered to the back surface of the semiconductor wafer, before dicing the semiconductor wafer, the protective film is formed from the base material side of the protective film forming composite sheet. (Hereinafter, may be referred to as “laser printing”) by irradiating the surface of the protective film with a laser beam. In this case, gas is generated by the decomposition of the protective film from the laser beam irradiated portion of the protective film along with the laser printing, but the generated gas is generated because the peeling force between the adhesive layer and the protective film is sufficiently large as described above. , The peeling between the pressure-sensitive adhesive layer and the protective film is suppressed, and the occurrence of gas accumulation is suppressed. As a result, not only can the dicing be stably performed as described above, but also the print applied to the protective film can be clearly and visually recognized through the base material and the pressure-sensitive adhesive layer.

On the other hand, in the composite sheet for forming a protective film according to the present invention, the layer in the pressure-sensitive adhesive layer which is in contact with the film for forming a protective film contains the (meth) acrylic acid alkyl ester copolymer in the above specific range. By doing so, after the pressure-sensitive adhesive layer is cured, the peeling force between the cured product of the pressure-sensitive adhesive layer and the protective film is sufficiently small, and the semiconductor chip with the protective film can be stably and easily picked up. The occurrence of chip breakage and chipping is suppressed.
Hereinafter, each configuration of the composite sheet for forming a protective film according to the present invention will be described in detail.

<Substrate>
The material of the base material is preferably various resins, and specific examples thereof include polyethylene (low-density polyethylene (may be abbreviated as LDPE), linear low-density polyethylene (may be abbreviated as LLDPE), High-density polyethylene (may be abbreviated as HDPE etc.)), polypropylene, ethylene-propylene copolymer, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride fill, vinyl chloride copolymer, polyethylene terephthalate, polyethylene naphthalate, poly Butylene terephthalate, polyurethane, polyurethane acrylate, polyimide, ethylene / vinyl acetate copolymer, ionomer resin, ethylene / (meth) acrylic acid copolymer, ethylene / (meth) acrylate copolymer, polystyrene, polycarbonate , Fluororesin, hydrogenated product of any of these resins, modified products, include cross-linked product or copolymer and the like.
In this specification, “(meth) acrylic acid” is a concept including both “acrylic acid” and “methacrylic acid”.

The thickness of the substrate can be appropriately selected according to the purpose, but is preferably 50 to 300 μm, and more preferably 60 to 100 μm. When the thickness of the base material is within such a range, the flexibility of the composite sheet for forming a protective film and the adhesion to a semiconductor wafer or a semiconductor chip are further improved.
The “thickness” in the present specification can be determined by a method defined in JIS K 7130: 1999 (ISO 4593: 1993).

The substrate may be composed of one layer (single layer) or may be composed of two or more layers. When the substrate is composed of a plurality of layers, these layers may be the same or different from each other. That is, all the layers may be the same, all the layers may be different, or only some of the layers may be the same. When the plurality of layers are different from each other, the combination of the plurality of layers is not particularly limited. Here, that a plurality of layers are different from each other means that at least one of the material and the thickness of each layer is different from each other.
In the case where the base material is composed of a plurality of layers, the total thickness of each layer is preferably set to the preferable thickness of the base material.

  In order to improve the adhesiveness with the pressure-sensitive adhesive layer provided thereon, the substrate is subjected to sand blasting, roughening treatment by solvent treatment, corona discharge treatment, electron beam irradiation treatment, plasma treatment, ozone / ultraviolet irradiation treatment. The surface may be subjected to an oxidation treatment such as a flame treatment, a chromic acid treatment, or a hot air treatment. Further, the substrate may be one whose surface has been subjected to a primer treatment.

<Adhesive layer>
The pressure-sensitive adhesive layer has an active energy ray-curable property, and at least a layer in contact with the protective film-forming film contains a (meth) acrylic acid alkyl ester copolymer. However, the (meth) acrylic acid alkyl ester copolymer has a constitutional unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group constituting the alkyl ester.
"Induced" means that the chemical structure changes due to polymerization.
In this specification, the term “active energy ray” means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include an ultraviolet ray and an electron beam.
The ultraviolet light can be emitted by using, for example, a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like as an ultraviolet light source. The electron beam can be emitted from an electron beam generated by an electron beam accelerator or the like.

  The thickness of the pressure-sensitive adhesive layer can be appropriately selected according to the purpose, but is preferably 1 to 100 μm, more preferably 1 to 60 μm, and particularly preferably 1 to 30 μm.

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing the (meth) acrylic acid alkyl ester copolymer and the like. The content ratio of components that do not vaporize at room temperature in the pressure-sensitive adhesive composition is usually the same as the content ratio of the components in the pressure-sensitive adhesive layer. In this specification, “normal temperature” means a temperature at which cooling or heating is not particularly performed, that is, a normal temperature, and includes, for example, a temperature of 15 to 25 ° C.
Next, the pressure-sensitive adhesive composition containing the (meth) acrylic acid alkyl ester copolymer, and the components of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive will be described.

[Adhesive composition]
(Alkyl (meth) acrylate copolymer)
The alkyl (meth) acrylate copolymer has a constitutional unit derived from an alkyl (meth) acrylate in which the alkyl group constituting the alkyl ester has 8 or more carbon atoms. In the present specification, the term “alkyl (meth) acrylate” simply means “(meth) acrylic acid in which the alkyl group constituting the alkyl ester has 8 or more carbon atoms, unless otherwise specified. Alkyl ester ".

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

  The alkyl group constituting the alkyl ester may have at least 8 carbon atoms, for example, at least 11 carbon atoms. The alkyl group constituting the alkyl ester preferably has 18 or less carbon atoms. That is, a preferable range of the number of carbon atoms of the alkyl group constituting the alkyl ester is 8 to 18, and an example thereof is 11 to 18. An alkyl (meth) acrylate having an alkyl group having 19 or more carbon atoms in the alkyl ester is difficult to handle, for example, has low solubility. That is, when the alkyl group constituting the alkyl ester has 18 or less carbon atoms, the solubility is good and the handling is easy.

  Further, by using the (meth) acrylic acid alkyl ester copolymer in which the alkyl group constituting the alkyl ester has 8 or more carbon atoms, the (meth) acrylic acid alkyl ester copolymer having the carbon number of less than 7 is used. The pressure-sensitive adhesive layer has a lower polarity than in the case of using the union. Therefore, for example, when the protective film-forming film contains a highly polar material such as an epoxy resin, in the protective film-forming composite sheet, the transition from the protective film-forming film of the high polar material to the pressure-sensitive adhesive layer occurs. Is suppressed. As a result, a decrease in the thermosetting property of the protective film-forming film is effectively suppressed. Then, since the degree of thermosetting by heating the film for forming a protective film is increased, the pickup property of a semiconductor chip with a protective film described later is improved.

Preferred examples of the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group include n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, N-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (also called lauryl (meth) acrylate), (meth) Tridecyl acrylate, tetradecyl (meth) acrylate (also called myristyl (meth) acrylate), pentadecyl (meth) acrylate, hexadecyl (meth) acrylate (also called palmityl (meth) acrylate), (meth) acrylic Heptadecyl acid, octadecyl (meth) acrylate ((meth) (Meth) acrylic acid alkyl esters in which the alkyl group is a chain, such as stearyl acrylate (also referred to as stearyl acrylate), isooctadecyl (meth) acrylate (also referred to as isostearyl (meth) acrylate); isobornyl (meth) acrylate And cycloalkyl (meth) acrylates such as dicyclopentanyl (meth) acrylate.
Of the above, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and isostearyl (meth) acrylate are preferred.

  Examples of the (meth) acrylic acid alkyl ester copolymer include an active energy ray polymerizable polymer which is polymerized by irradiation with an active energy ray. Preferred examples of such a copolymer include a polymerizable group having a hydroxyl group (for example, a (meth) acryloyl group, a vinyl group (ethenyl group), an allyl group (2-propenyl group), and the like. And a (meth) acryloyl group is preferable) in the side chain. Among them, those having a hydroxyl group and having a polymerizable group in the side chain via a urethane bond are more preferable. Such a (meth) acrylic acid alkyl ester copolymer is crosslinked, for example, by reacting a hydroxyl group of the copolymer with an isocyanate group in an isocyanate-based crosslinking agent described later. In addition, such a (meth) acrylic acid alkyl ester copolymer has a polymerizable group in a side chain, for example, by separately using a low-molecular-weight active energy ray polymerizable compound, and irradiating with an active energy ray. By performing a polymerization reaction without using such a compound separately from the case of performing a polymerization reaction, the peelability of the pressure-sensitive adhesive layer after the polymerization reaction from the protective film due to a decrease in the adhesiveness is improved, and a semiconductor chip with a protective film is obtained. The pick-up property for easy pick-up is improved. Further, since it is not necessary to separately use a low-molecular-weight active energy ray-polymerizable compound, the migration of such a low-molecular-weight active energy ray-polymerizable compound from the pressure-sensitive adhesive layer to the protective film-forming film is suppressed, and the protective film Changes in the properties of the film for formation are suppressed.

  The above-mentioned preferable alkyl (meth) acrylate copolymer is, for example, a composition containing an alkyl (meth) acrylate and a hydroxyl group-containing monomer, and these monomers are polymerized to form a copolymer (hereinafter, referred to as “prepolymer”). Is obtained by reacting a hydroxyl group of the copolymer (pre-copolymer) with an isocyanate group of a compound having an isocyanate group and a polymerizable group.

  Among the (meth) acrylic acid alkyl ester copolymers, more preferred are, for example, the above (meth) acrylic acid alkyl ester and hydroxyl group-containing (meth) acrylic acid ester as essential monomers, and copolymerization of these monomers. Those obtained by reacting the isocyanate group of the compound having an isocyanate group and a polymerizable group with the hydroxyl group of the pre-copolymer obtained as described above.

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

  Examples of the compound having an isocyanate group and a polymerizable group include isocyanate compounds such as 2- (meth) acryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, and allyl isocyanate. Of these, 2-methacryloyloxyethyl isocyanate is preferred.

  The above-mentioned preferable alkyl (meth) acrylate copolymer may be obtained by further reacting an arbitrary compound in addition to the above-mentioned essential monomer and compound, and the arbitrary compound may be, for example, a monomer. Alternatively, a compound obtained by copolymerizing a monomer may be used. Examples of the monomer which is the arbitrary compound include, for example, a hydroxyl group-free (meth) acrylic ester which does not correspond to the above (meth) acrylic acid alkyl ester, (meth) acrylic acid, itaconic acid, a non (meth) acrylic monomer, and the like. Is mentioned.

  Examples of the hydroxyl group-free (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester is linear or branched and has 1 to 7 carbon atoms, such as hexyl (meth) acrylate and heptyl (meth) acrylate; ) Aralkyl (meth) acrylate such as benzyl acrylate; cycloalkenyl (meth) acrylate such as dicyclopentenyl (meth) acrylate; (meth) such as dicyclopentenyloxyethyl ethyl (meth) acrylate Acrylic acid cycloalkenyloxyalkyl ester; (meth) acrylic acid i De; (meth) containing a glycidyl group of glycidyl acrylate (meth) acrylic acid ester.

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

  For preparing the (meth) acrylic acid alkyl ester copolymer, such as the (meth) acrylic acid alkyl ester, the hydroxyl group-containing (meth) acrylic acid ester, the compound having an isocyanate group and a polymerizable group, and the optional compound. The components used (that is, the constituent components of the copolymer) may be only one kind or two or more kinds.

The proportion of the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group is 30 mass% with respect to the total mass of all the monomers used for the preparation of the (meth) acrylic acid alkyl ester copolymer. % Or more, and more preferably 35% by mass or more.
In other words, the content of the structural unit derived from the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group is the same as that of all the structural units constituting the (meth) acrylic acid alkyl ester copolymer. It is preferably at least 30% by mass, more preferably at least 35% by mass, based on the total mass.

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 (meth) acrylic acid alkyl ester copolymer is not particularly limited. Can be selected from, for example, any of 85% by mass, 90% by mass, and 95% by mass with respect to the total mass of all the constituent units constituting, and may be 100% by mass.
That is, the proportion of the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group is based on the total mass of all the monomers used in the preparation of the (meth) acrylic acid alkyl ester copolymer. 30 mass% or more and 100 mass% or less, 30 mass% or more and 95 mass% or less, 30 mass% or more and 90 mass% or less, and 30 mass% or more and 85 mass% or less. There may be.
As still another aspect, the content may be 35% by mass or more and 100% by mass or less, 35% by mass or more and 95% by mass or less, or 35% by mass or more and 90% by mass or less. And it may be 35% by mass or more and 85% by mass or less.
As still another aspect, the content may be 40% by mass or more and 80% by mass or less.
As still another aspect, the content of the structural unit derived from the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group constitutes the (meth) acrylic acid alkyl ester copolymer. It may be 30% by mass or more and 100% by mass or less, 30% by mass or more and 95% by mass or less, or 30% by mass or more and 90% by mass or less based on the total mass of all constituent units. , 30% by mass or more and 85% by mass or less.
As still another aspect, the content may be 35% by mass to 100% by mass, 35% by mass to 95% by mass, or 35% by mass to 90% by mass. And it may be 35% by mass or more and 85% by mass or less.
As still another aspect, the content may be 40% by mass or more and 80% by mass or less.

  The pressure-sensitive adhesive layer may contain only one type of the (meth) acrylic acid alkyl ester copolymer or two or more types.

  The content of the (meth) acrylic acid alkyl ester copolymer is preferably at least 75% by mass, more preferably at least 80% by mass, based on the total mass of the pressure-sensitive adhesive layer. And in order to form such an adhesive layer, the content of the (meth) acrylic acid alkyl ester copolymer in the adhesive composition is determined by the total amount of components other than the solvent in the adhesive composition. It is preferably at least 75% by mass, more preferably at least 80% by mass, based on the total mass.

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. In consideration of using other components in combination as described later, the content is preferably 97% by mass, and more preferably 95% by mass.
That is, the content of the (meth) acrylic acid alkyl ester copolymer may be 75% by mass or more and 100% by mass or less with respect to the total mass of the pressure-sensitive adhesive layer, and may be 75% by mass or more and 97% by mass or less. Preferably, it is 80% by mass or more and 95% by mass or less.
As another aspect, the content of the alkyl (meth) acrylate copolymer in the pressure-sensitive adhesive composition is 75% by mass based on the total mass of all components other than the solvent in the pressure-sensitive adhesive composition. It is sufficient that the amount is not less than 100% by mass and not more than 75% by mass and not more than 97% by mass, and more preferably not less than 80% by mass and not more than 95% by mass.

  In the case where the (meth) acrylic acid alkyl ester copolymer has a hydroxyl group and further has a polymerizable group in a side chain, preferred examples of the pressure-sensitive adhesive composition include, for example, the (meth) ) In addition to the acrylic acid alkyl ester copolymer, those further containing an isocyanate-based crosslinking agent and a photopolymerization initiator may be mentioned.

(Isocyanate crosslinking agent)
The isocyanate-based cross-linking agent is not particularly limited as long as it is a cross-linking agent having an isocyanate group (-N = C = O), and is preferably, for example, 2,4-tolylene diisocyanate; 1,3-xylylene diisocyanate; 1,4-xylylene diisocyanate; diphenylmethane-4,4'-diisocyanate;diphenylmethane-2,4'-diisocyanate; 3-methyldiphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane -4,4′-diisocyanate; dicyclohexylmethane-2,4′-diisocyanate; tolylene diisocyanate, hexamethyl Compounds to which at least one of diisocyanate and xylylene diisocyanate are added; lysine diisocyanate and the like.

  The pressure-sensitive adhesive composition may contain one or more isocyanate-based crosslinking agents.

  The content of the isocyanate-based crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.01 to 20 parts by mass, when the content of the (meth) acrylic acid alkyl ester copolymer is 100 parts by mass. , 0.1 to 10 parts by mass.

(Photopolymerization initiator)
The photopolymerization initiator may be a known one, and specifically, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethyl Acetophenone, 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2 Α-ketol compounds such as -methyl-propan-1-one; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio) -Phenyl] -2-morpholinopropane-1 and other acetophenone-based compounds; benzoin ethyl ether, benzene Benzoin ether compounds such as in-isopropyl ether and anisoin methyl ether; ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalene sulfonyl chloride; 1-phenone-1,1-propanedione-2 A photoactive oxime compound such as-(o-ethoxycarbonyl) oxime; a benzophenone compound such as benzophenone, benzoylbenzoic acid, or 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, Thioxanthone compounds such as methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone Camphorquinone, halogenated ketones, acyl phosphino sulfoxide; acyl phosphonium diisocyanate and the like.

  The content of the photopolymerization initiator in the pressure-sensitive adhesive composition is preferably 0.05 to 20 parts by mass, when the content of the (meth) acrylic acid alkyl ester copolymer is 100 parts by mass. .

(solvent)
The pressure-sensitive adhesive composition preferably further contains a solvent in addition to the (meth) acrylic acid alkyl ester copolymer.
The solvent is not particularly limited, but preferred solvents are, for example, hydrocarbons having 7 to 9 carbon atoms such as toluene and xylene; methanol, ethanol, 2-propanol, and isobutyl alcohol (also known as 2-methylpropan-1-ol). Alcohols having 1 to 6 carbon atoms such as 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; amides such as dimethylformamide and N-methylpyrrolidone (that is, an amide bond). Compounds having the same).
Of the above, methyl ethyl ketone, toluene and ethyl acetate are preferred.
The solvent contained in the pressure-sensitive adhesive composition may be only one kind or two or more kinds.

  When the pressure-sensitive adhesive composition contains a solvent, the content of the solvent is preferably such that the solid content concentration of the composition is 10 to 50% by mass based on the total mass of the composition. .

(Other components)
In addition to the (meth) acrylic acid alkyl ester copolymer, the pressure-sensitive adhesive composition does not fall under any of the isocyanate-based crosslinking agent, photopolymerization initiator, and solvent as long as the effects of the present invention are not impaired. Other components may be contained.
The other components may be known ones, can be arbitrarily selected according to the purpose, and are not particularly limited. Preferred examples thereof include, for example, dyes, pigments, deterioration inhibitors, antistatic agents, flame retardants, silicone compounds, Various additives such as a chain transfer agent are included.

  The pressure-sensitive adhesive layer may be composed of one layer (single layer) or may be composed of two or more layers. When the pressure-sensitive adhesive layer is composed of plural layers, these plural layers may be the same or different from each other. That is, all the layers may be the same, all the layers may be different, or only some of the layers may be the same. When the plurality of layers are different from each other, the combination of the plurality of layers is not particularly limited. Here, “a plurality of layers are different from each other” means the same as in the case of the above-described base material.

  However, when the pressure-sensitive adhesive layer is composed of one layer (single layer), the pressure-sensitive adhesive layer must be formed by using the (meth) acrylic acid alkyl ester copolymer obtained by using the pressure-sensitive adhesive composition described above. It becomes a layer containing. When the pressure-sensitive adhesive layer is composed of a plurality of layers, of the plurality of layers, the layer that is in contact with at least the protective film-forming film (that is, the most distant from the substrate in the thickness direction of the pressure-sensitive adhesive layer) (Hereinafter, sometimes referred to as an uppermost layer) is always a layer containing the (meth) acrylic acid alkyl ester copolymer obtained using the above-mentioned pressure-sensitive adhesive composition. When the pressure-sensitive adhesive layer is composed of a plurality of layers, at least one layer other than the layer in contact with the protective film-forming film is a layer containing the (meth) acrylic acid alkyl ester copolymer. Or a layer not containing all the (meth) acrylic acid alkyl ester copolymer, or a layer containing only a part of the (meth) acrylic acid alkyl ester copolymer. Good.

When the pressure-sensitive adhesive layer is composed of a single layer, the composite sheet for forming a protective film has an advantage that the structure is simplified and the composite sheet can be manufactured at low cost.
On the other hand, when the pressure-sensitive adhesive layer is composed of a plurality of layers, as described above, of the plurality of layers, the layer that is in contact with the protective film forming film (that is, the uppermost layer) is the (meth) acrylic layer. The effect of the present invention can be obtained by forming a layer containing the acid alkyl ester copolymer. Further, of these multiple layers, a layer in contact with the base material (that is, a layer adjacent to the base material in the thickness direction of the pressure-sensitive adhesive layer, hereinafter sometimes referred to as a lowermost layer), for example, By forming a layer having particularly high adhesion to the substrate, the composite sheet for forming a protective film has further improved stability during use. As described above, by forming the pressure-sensitive adhesive layer as a laminate including a plurality of layers, there is an advantage that the pressure-sensitive adhesive layer as a whole can be adjusted to a layer having two or more characteristics.

  When the pressure-sensitive adhesive layer is composed of a plurality of layers, the pressure-sensitive adhesive layer containing no alkyl (meth) acrylate copolymer may be, for example, the same as the conventional pressure-sensitive adhesive layer.

  When the pressure-sensitive adhesive layer is composed of a plurality of layers, the total thickness of each layer is preferably set to the preferable thickness of the pressure-sensitive adhesive layer.

<Protective film forming film>
The film for forming a protective film has thermosetting properties and may have pressure-sensitive adhesive properties, or may be capable of being applied to various adherends by being heated and softened. The film for forming the protective film finally becomes a high impact-resistant protective film after thermosetting, and this protective film has excellent shear strength and maintains sufficient adhesive properties even under severe high temperature and high humidity conditions. obtain.

  The thickness of the protective film-forming film is not particularly limited, but is preferably 1 to 100 μm, more preferably 5 to 75 μm, and particularly preferably 5 to 50 μm. When the thickness of the protective film-forming film is equal to or more than the lower limit, the adhesive strength to the semiconductor wafer and the semiconductor chip as the adherend is further increased. In addition, when the thickness of the protective film forming film is equal to or less than the upper limit value, the protective film which is a cured product can be more easily cut using a shearing force when the semiconductor chip is picked up.

The film for forming a protective film is not particularly limited as long as it is a thermosetting film.
Preferred protective film-forming films include, for example, those containing a polymer component (A) and a thermosetting component (B). The polymer component (A) is a component that can be regarded as formed by a polymerization reaction of the polymerizable compound.
Further, the thermosetting component (B) is a component that can be cured (polymerized) by heat. In the present invention, the polymerization reaction includes a polycondensation reaction.

[Protective film forming composition]
The film for forming a protective film can be formed from a composition for forming a protective film containing components for constituting the film. In the composition for forming a protective film, the content ratio of components that do not vaporize at room temperature is usually the same as the content ratio of the components in the film for forming a protective film.
Preferred protective film forming compositions include, for example, those containing a polymer component (A) and a thermosetting component (B), and include a polymer component (A), a thermosetting component (B) and a curable component. Those containing the accelerator (C) are more preferred. Next, the components contained in the composition for forming a protective film and the film for forming a protective film will be described.

(Polymer component (A))
The polymer component (A) is a polymer compound for imparting a film-forming property, flexibility and the like to the protective film-forming film. The polymer component (A) may also correspond to the thermosetting component (B).
For example, a phenoxy resin, an acrylic resin having an epoxy group in a side chain, and the like correspond to the polymer component (A) and also correspond to the thermosetting component (B) in some cases. Such a component is handled as the polymer component (A).
As the polymer component (A), one type may be used alone, or two or more types may be used in combination.

  Examples of the polymer component (A) include acrylic resins, polyesters, polyurethanes, acrylic urethane resins, silicone resins, rubber polymers, phenoxy resins, and the like, with acrylic resins being preferred.

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, and more preferably from 100,000 to 1500,000. When the weight average molecular weight of the acrylic resin is equal to or more than the lower limit, the adhesion between the protective film described below and the pressure-sensitive adhesive layer after curing is suppressed, and the pickup property of the semiconductor chip with the protective film is further improved. I do.
In addition, since the weight average molecular weight of the acrylic resin is equal to or less than the upper limit, the protective film forming film easily follows the uneven surface of the adherend, and between the adherend and the protective film forming film. Generation of voids and the like is further suppressed.
In addition, in this specification, "weight average molecular weight" is a polystyrene conversion value measured by a gel permeation chromatography (GPC) method, unless otherwise specified.

  The glass transition temperature (Tg) of the acrylic resin is preferably −60 to 70 ° C., and more preferably −30 to 50 ° C. When the Tg of the acrylic resin is equal to or more than the lower limit, the peeling force between the protective film described below and the pressure-sensitive adhesive layer after curing is reduced, and the pickup property of the semiconductor chip with the protective film is further improved. Further, when the Tg of the acrylic resin is equal to or less than the upper limit, the adhesive force between the protective film forming 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, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( Isooctyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, (meth) acrylic acid Dodecyl (lauryl (meth) acrylate), tridecyl (meth) acrylate, tetradecyl (meth) acrylate (myristyl (meth) acrylate), pentadecyl (meth) acrylate, hexadecyl (meth) acrylate ((meth) acryl) Acid palmityl), heptadecyl (meth) acrylate, Such as Le octadecyl (stearyl (meth) acrylate), is 1 to 18 carbon atoms the alkyl group having a chain constituting the alkyl ester (meth) acrylic acid alkyl ester;
Cycloalkyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate (Meth) acrylic esters having a cyclic skeleton such as ethyl and (meth) acrylic imide;
Hydroxyl-containing (meth) acrylates such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate;
Glycidyl group-containing (meth) acrylates such as glycidyl (meth) acrylate are exemplified.
Further, the acrylic resin may be a resin obtained by copolymerizing monomers such as acrylic acid, methacrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.
The monomer constituting the acrylic resin may be only one kind or two or more kinds.

  The acrylic resin may have a functional group that can bind to other compounds such as a vinyl group, a (meth) acryloyl group, an amino group, a hydroxyl group, a carboxy group, and an isocyanate group. The functional group may be bonded to another compound via a cross-linking agent (F) described below, or may be directly bonded to another compound without using a cross-linking agent (F). When the acrylic resin is bonded to another compound by the functional group, the package reliability of the semiconductor device obtained 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 composition for forming a protective film is different from the solvent in the composition for forming a protective film. It is preferably from 5 to 50% by mass based on the total mass of all components. When the content of the acrylic resin is in such a range, the peeling force between the protective film and the pressure-sensitive adhesive layer after curing is reduced, and the pickup property of the semiconductor chip with the protective film is further improved.
As described above, when the protective film-forming film contains an acrylic resin as the polymer component (A), the content of the acrylic resin in the protective film-forming film is based on the total mass of the protective film forming film. Is preferably 5 to 50% by mass.

  In the present invention, by reducing the adhesive force (sometimes referred to as peeling force) between the protective film and the pressure-sensitive adhesive layer after curing, the pickup property of the semiconductor chip with the protective film can be further improved or the adhesion can be improved. Since the film for forming a protective film easily follows the uneven surface of the body, the generation of voids and the like between the adherend and the film for forming a protective film is further suppressed. A thermoplastic resin other than the acrylic resin (hereinafter, may be simply abbreviated as “thermoplastic resin”) may be used alone or in combination with the acrylic resin.

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

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

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

  As the thermoplastic resin, one type may be used alone, or two or more types may be used in combination.

(Thermosetting component (B))
The thermosetting component (B) is a component for curing the protective film-forming film to form a hard protective film. The thermosetting component (B) may also correspond to the polymer component (A), but such a component is handled as the polymer component (A).
As the thermosetting component (B), one type may be used alone, or two or more types may be used in combination.

  Examples of the thermosetting component (B) include an epoxy thermosetting resin, a thermosetting polyimide resin, a polyurethane, an unsaturated polyester, and a silicone resin, and an epoxy thermosetting resin is preferable.

-Epoxy thermosetting resin Epoxy thermosetting resin is composed of epoxy resin (B11) and thermosetting agent (B12).
One type of epoxy-based thermosetting resin may be used alone, or two or more types may be used in combination.

  Examples of the epoxy resin (B11) include known ones. Examples thereof include a polyfunctional epoxy resin, a biphenyl compound, bisphenol A diglycidyl ether and a hydrogenated product thereof, orthocresol novolak epoxy resin, dicyclopentadiene type epoxy resin, Biphenyl or higher functional epoxy compounds such as biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenylene skeleton type epoxy resin and the like. Among them, bisphenol A type epoxy resin and dicyclopentadiene type epoxy resin are preferable.

As the epoxy resin (B11), an epoxy resin having an unsaturated hydrocarbon group may be used.
Examples of the epoxy resin having an unsaturated hydrocarbon group include a compound in which a part of the epoxy group of the polyfunctional epoxy resin is converted to a group containing an unsaturated hydrocarbon group.

The number average molecular weight of the epoxy resin (B11) is not particularly limited, but is preferably from 100 to 20,000 from the viewpoint of the curability of the protective film-forming film, and the strength and heat resistance of the cured protective film.
The “number average molecular weight” here is a value in terms of polystyrene measured by gel permeation chromatography (GPC).
The epoxy equivalent of the epoxy resin (B11) is preferably from 100 to 1100 g / eq, and more preferably from 150 to 1000 g / eq.

  As the epoxy resin (B11), one type may be used alone, or two or more types may be used in combination.

The thermosetting agent (B12) functions as a curing agent for the epoxy resin (B11).
Examples of the thermosetting agent (B12) include compounds having two or more functional groups capable of reacting with an epoxy group in one molecule. Examples of the functional group include a phenolic hydroxyl group, an alcoholic hydroxyl group, an amino group, a carboxy group, a group in which an acid group has been converted to an anhydride, and a phenolic hydroxyl group, an amino group, or an acid group in which an acid group has been converted to an anhydride. It is preferably a phenolic hydroxyl group or an amino group, and more preferably an amino group.

Among the thermosetting agents (B12), examples of the phenolic curing agent having a phenolic hydroxyl group include a polyfunctional phenol resin, biphenol, a novolak phenol resin, a dicyclopentadiene phenol resin, and an aralkyl phenol resin.
Among the thermosetting agents (B12), examples of the amine-based curing agent having an amino group include dicyandiamide (hereinafter may be abbreviated as “DICY”).

The thermosetting agent (B12) may have an unsaturated hydrocarbon group.
Examples of the thermosetting agent (B12) having an unsaturated hydrocarbon group include a compound in which a part of a hydroxyl group of a phenol resin is substituted by a group having an unsaturated hydrocarbon group, and an aromatic ring of a phenol resin. Examples include compounds in which a group having a saturated hydrocarbon group is directly bonded.
The unsaturated hydrocarbon group in the thermosetting agent (B12) is the same as the unsaturated hydrocarbon group in the epoxy resin having an unsaturated hydrocarbon group described above.

  As the thermosetting agent (B12), one type may be used alone, or two or more types may be used in combination.

The thermosetting agent (B12) is a solid which is solid at normal temperature and does not show curing activity for the epoxy resin (B11), while it is dissolved by heating and shows curing activity for the epoxy resin (B11). It is preferably a curing agent (hereinafter sometimes abbreviated as “solid dispersion type latent curing agent”). That is, the film for forming a protective film preferably contains an epoxy resin (B11) and the solid dispersion type latent curing agent as a thermosetting 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 to form the epoxy resin ( B11). By using the solid dispersion type latent curing agent, the storage stability of the composite sheet for forming a protective film is significantly improved. For example, the movement of the curing agent from the protective film forming film to the adjacent pressure-sensitive adhesive layer is suppressed, and a decrease in the thermosetting property of the protective film forming film is effectively suppressed. Then, since the degree of thermosetting by heating the film for forming a protective film is further increased, the pickup property of a semiconductor chip with a protective film described later is further improved.

  Examples of the solid dispersion type latent curing agent include onium salts, dibasic acid hydrazide, dicyandiamide, amine adducts of the curing agent, and the like.

The content of the thermosetting agent (B12) in the composition for forming a protective film and the film for forming a protective film is 0.1 to 500 parts by mass when the content of the epoxy resin (B11) is 100 parts by mass. And more preferably 1 to 200 parts by mass. When the content of the thermosetting agent (B12) is equal to or more than the lower limit, the curing of the film for forming a protective film is further facilitated.
In addition, when the content of the thermosetting agent (B12) is equal to or less than the upper limit, the moisture absorption of the protective film-forming film is reduced, and the package reliability is further improved.

  The content of the thermosetting component (B) in the composition for forming a protective film and the film for forming a protective film is 1 to 100 parts by mass, when the content of the polymer component (A) is 100 parts by mass. Is preferably 1.5 to 85 parts by mass, and particularly preferably 2 to 70 parts by mass. When the content of the thermosetting component (B) is in such a range, the adhesive force (peeling force) between the protective film and the pressure-sensitive adhesive layer after curing becomes smaller, and the semiconductor chip with the protective film is provided. The pick-up property is further improved.

(Curing accelerator (C))
The curing accelerator (C) is a component for adjusting the curing speed of the composition for forming a protective film.
Preferred curing accelerators (C) include, for example, tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol; 2-methylimidazole, 2-phenylimidazole , 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole and the like (that is, at least one hydrogen atom is hydrogen) Organic phosphines such as tributylphosphine, diphenylphosphine, and triphenylphosphine (phosphines in which at least one hydrogen atom is substituted with an organic group); tetraphenylphosphonium Tiger tetraphenylborate, tetraphenyl boron salts such as triphenyl phosphine tetraphenyl borate and the like.
Among the above, 2-phenyl-4,5-dihydroxymethylimidazole is preferred.

  As the curing accelerator (C), one type may be used alone, or two or more types may be used in combination.

Particularly when the composition for forming a protective film contains the solid dispersion type latent curing agent as a thermosetting agent (B12), it is preferable to contain the imidazoles as a curing accelerator (C). That is, the protective film forming film preferably contains an epoxy resin (B11), the solid dispersion type latent curing agent as a thermosetting agent (B12), and imidazoles as a curing accelerator (C). .
That is, one side of the protective film forming film is composed of a polymer component (A), an epoxy resin (B11), the solid dispersion type latent curing agent as a thermosetting agent (B12), and a curing accelerator (C). )) And imidazoles.

  When the curing accelerator (C) is used, the content of the curing accelerator (C) in the composition for forming a protective film and the film for forming a protective film is such that the content of the thermosetting component (B) is 100 parts by mass. At this time, it is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 4 parts by mass. When the content of the curing accelerator (C) is in such a range, the protective film-forming film has excellent adhesive properties even under high temperature and high humidity conditions and is exposed to severe reflow conditions. However, high package reliability can be achieved. When the content of the curing accelerator (C) is equal to or more than the lower limit, the effect of using the curing accelerator (C) is more remarkably obtained. When the content of the curing accelerator (C) is equal to or less than the upper limit, the curing accelerator (C) generally has high polarity, but is a film for forming a protective film under high temperature and high humidity conditions. By suppressing the precipitation at the bonding interface with the adherend in the inside, the reliability of the package is improved.

In order to improve various physical properties, the film for forming a protective film does not correspond to the polymer component (A), the thermosetting component (B) and the curing accelerator (C), and if necessary, does not correspond thereto. It may be formed from a protective film-forming composition containing other components.
Examples of the other components contained in the composition for forming a protective film and the film for forming a protective film include a filler (D), a coupling agent (E), a cross-linking agent (F), and a general-purpose additive (G). Is mentioned.

(Filler (D))
The composition for forming a protective film usually contains the filler (D), so that the thermal expansion coefficient can be easily adjusted. Therefore, the package reliability can be improved by optimizing the thermal expansion coefficient of the cured protective film with respect to the semiconductor chip by using such a protective film forming composition.
Further, usually, by using the composition for forming a protective film containing the filler (D), the moisture absorption of the protective film after curing can also be reduced.

The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler.
Preferred inorganic fillers include, for example, powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, boron nitride, etc .; beads obtained by sphericalizing these silicas; single crystal fibers of these silicas; glass Fiber and the like.
Among these, the inorganic filler is preferably a silica filler or an alumina filler.

  As the filler (D), one type may be used alone, or two or more types may be used in combination.

  When the filler (D) is used, the content of the filler (D) relative to the total mass of the components other than the solvent of the composition for forming a protective film (that is, the content of the filler (D) in the film for forming a protective film) ) Is preferably from 5 to 80% by mass, more preferably from 7 to 60% by mass. When the content of the filler (D) is in such a range, the adjustment of the above-described coefficient of thermal expansion becomes easier.

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

The coupling agent (E) is preferably a compound having a functional group that reacts with a functional group of the polymer component (A), the thermosetting component (B), and the like, and is preferably a silane coupling agent. .
Preferred silane coupling agents include, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ- ( (Methacryloxypropyl) trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-6- (aminoethyl) -γ-aminopropylmethyldiethoxysilane N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis (3-triethoxysilylpropyl) tetrasulfane, Methyl trime Examples include toxic silane, methyl triethoxy silane, vinyl trimethoxy silane, vinyl triacetoxy silane, and imidazole silane.

  As the coupling agent (E), one type may be used alone, or two or more types may be used in combination.

  When the coupling agent (E) is used, the content of the coupling agent (E) in the composition for forming a protective film and the film for forming a protective film depends on the total amount of the polymer component (A) and the thermosetting component (B). When the content is 100 parts by mass, it is preferably 0.03 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass. . When the content of the coupling agent (E) is equal to or more than the lower limit, the effect of using the coupling agent (E) is more remarkably obtained, and the content of the coupling agent (E) is reduced. By being equal to or less than the upper limit, the generation of outgas is further suppressed.

(Crosslinking agent (F))
When the above-mentioned acrylic resin having a functional group such as a vinyl group, a (meth) acryloyl group, an amino group, a hydroxyl group, a carboxy group, or an isocyanate group that can be bonded to another compound is used as the polymer component (A). A cross-linking agent (F) can be used to bond and cross-link this functional group with another compound. By performing crosslinking using the crosslinking agent (F), the initial adhesive strength and cohesive strength of the protective film-forming film can be adjusted.

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

  Examples of the organic polyvalent isocyanate compound include aromatic polyvalent isocyanate compounds, aliphatic polyvalent isocyanate compounds, alicyclic polyvalent isocyanate compounds, and trimers, isocyanurates, and adducts of these compounds (ethylene glycol, A reaction product of a low-molecular-weight active hydrogen-containing compound such as propylene glycol, neopentyl glycol, trimethylolpropane, or castor oil, such as an adduct of xylylene diisocyanate with trimethylolpropane, or an organic polyvalent isocyanate compound and a polyol compound. And a terminal isocyanate urethane prepolymer obtained by reacting

  Examples of the organic polyisocyanate compound include 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate; 1,4-xylene diisocyanate; diphenylmethane-4,4'-diisocyanate Diphenylmethane-2,4'-diisocyanate; 3-methyldiphenylmethane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; dicyclohexylmethane-4,4'-diisocyanate; dicyclohexylmethane-2,4'-diisocyanate; Compounds in which one or both of tolylene diisocyanate and hexamethylene diisocyanate are added to all or some of the hydroxyl groups; Aneto and the like.

  Examples of the organic polyvalent imine compound include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, tetramethylolmethane -Tri-β-aziridinylpropionate, N, N′-toluene-2,4-bis (1-aziridinecarboxamide) triethylenemelamine and the like.

  When an isocyanate-based crosslinking agent is used as the crosslinking agent (F), it is preferable to use a hydroxyl group-containing polymer as the acrylic resin that is the polymer component (A). When the cross-linking agent (F) has an isocyanate group and the acrylic resin has a hydroxyl group, a cross-linked structure can be easily introduced into the protective film-forming film by the reaction between the cross-linking agent (F) and 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 0.01 to 20 parts by mass when the content of the polymer component (A) is 100 parts by mass. Is preferably 0.1 to 10 parts by mass, and particularly preferably 0.5 to 5 parts by mass.

(General purpose additive (G))
Examples of the general-purpose additive (G) include known plasticizers, antistatic agents, antioxidants, pigments, dyes, gettering agents, and the like.

(solvent)
It is preferable that the composition for forming a protective film further contains a solvent since the handleability is improved by dilution.
The solvent contained in the composition for forming a protective film may be the same as the solvent in the pressure-sensitive adhesive composition described above.
The solvent contained in the composition for forming a protective film may be only one kind or two or more kinds.
When the composition for forming a protective film contains a solvent, the content of the solvent is such that the solid content concentration of the composition for forming a protective film is 35 to 75% by mass based on the total mass of the composition for forming a protective film. It is preferable that the amount is such that

That is, another aspect of the composition for forming a protective film includes a polymer component (A), a thermosetting component (B), a curing accelerator (C), and, if desired, a solvent, a filler (D), And at least one selected from the group consisting of a coupling agent (E), a crosslinking agent (F), and a general-purpose additive (G).
Another aspect of the protective film forming film is that the polymer component (A), the thermosetting component (B), the curing accelerator (C), and if necessary, the filler (D) and the coupling agent (E) ), At least one selected from the group consisting of a crosslinking agent (F) and a general-purpose additive (G).
Further, the thermosetting component (B) includes an epoxy resin (B11) and the solid dispersion type latent curing agent as a thermosetting agent (B12), and the curing accelerator (C) includes imidazoles. It is preferred to include.

The composition for forming a protective film is obtained by blending the above-mentioned components for constituting the same.For example, except that the blending components are different, the composition is obtained in the same manner as in the case of the above-mentioned pressure-sensitive adhesive composition. Can be
When a solvent is used, the solvent may be mixed with any of the components other than the solvent, and may be used by previously diluting the components, or may be used by diluting any of the components other than the solvent in advance. Alternatively, a solvent may be used by mixing with these components.

  The composite sheet for forming a protective film may include a release film on an exposed surface such as the surface of the film for forming a protective film or the surface of an adhesive layer. The release film may be released (removed) when the composite sheet for forming a protective film is used.

FIG. 1 is a cross-sectional view schematically showing one embodiment of the composite sheet for forming a protective film according to the present invention.
The composite sheet 1 for forming a protective film shown here comprises an adhesive layer 12 on a substrate 11 and a film 13 for forming a protective film on the adhesive layer 12. It has a configuration in which a protective film forming film 13 is provided on the layer 12. The protective film forming composite sheet 1 further includes a release film 14 on the protective film forming film 13. The pressure-sensitive adhesive layer 12 which is in contact with the protective film forming film 13 has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group constituting the alkyl ester. ) A layer containing an alkyl acrylate copolymer.

In the composite sheet 1 for forming a protective film, the pressure-sensitive adhesive layer 12 is laminated on the surface 11 a of the base material 11, and the film 13 for forming the protective film is laminated on a part of the surface 12 a of the pressure-sensitive adhesive layer 12. The release film 14 is laminated on the exposed surface of the surface 12a of the pressure-sensitive adhesive layer 12 where the protective film forming film 13 is not laminated, and on the surface 13a (upper surface and side surfaces) of the protective film forming film 13. Have been.
A gap may be present between the release film 14 and the surface 12a of the pressure-sensitive adhesive layer 12 or the surface 13a of the protective film forming film 13. For example, of the surface 13 a of the protective film forming film 13, a region indicated by reference numeral 130 a (a region on the side of the adhesive layer 12) and a surface indicated by reference numeral 120 a of the surface 12 a of the adhesive layer 12 (a region indicated by reference numeral 120 a) (The region on the side of the film 13), the gap is easily formed between the film and the release film. That is, voids are likely to be formed in the vicinity of the boundary between the protective film forming film 13 and the pressure-sensitive adhesive layer 12 and in the region in contact with the release film 14.

  In the protective film forming composite sheet 1 shown in FIG. 1, the back surface of a semiconductor wafer (not shown) is attached to the front surface 13 a of the protective film forming film 13 with the release film 14 removed, and further, an adhesive layer Of the surface 12a of 12, the exposed surface on which the protective film forming film 13 is not laminated is attached to a jig such as a ring frame and used.

FIG. 2 is a sectional view schematically showing another embodiment of the composite sheet for forming a protective film according to the present invention. In FIG. 2, the same elements as those shown in FIG. 1 are denoted by the same reference numerals as in FIG. 1, and detailed description thereof will be omitted. This is the same in FIGS.
In the protective film forming composite sheet 2 shown here, a protective film forming film 23 is laminated on the entire surface 12a of the pressure-sensitive adhesive layer 12, and a jig adhesive is formed on a part of the surface 23a of the protective film forming film 23. The layer 15 is laminated, and of the surface 23 a of the protective film forming film 23, the exposed surface on which the jig adhesive layer 15 is not laminated, and the surface 15 a (top and side surfaces) of the jig adhesive layer 15. It is the same as the protective film forming composite sheet 1 shown in FIG. 1 except that the release film 14 is laminated thereon. The pressure-sensitive adhesive layer 12 that is in contact with the protective film forming film 23 has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group constituting the alkyl ester. ) Acrylic acid alkyl ester copolymer.
That is, one side of the composite sheet for forming a protective film according to the present invention includes:
Base material, adhesive layer, protective film forming film, jig adhesive layer, and release film, including,
The pressure-sensitive adhesive layer is laminated on the substrate,
The protective film forming film is laminated on the entire surface of the pressure-sensitive adhesive layer,
The jig adhesive layer is laminated on a part of the surface of the protective film forming film,
Of the surface of the protective film forming film, the exposed surface on which the jig adhesive layer is not laminated, and the upper surface and side surfaces of the jig adhesive layer, the release film is laminated,
The pressure-sensitive adhesive layer that is in contact with the protective film-forming film has a structural unit derived from an alkyl ester of (meth) acrylic acid having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester. Containing a (meth) acrylic acid alkyl ester copolymer,
It is a composite sheet for forming a protective film.

  The jig adhesive layer 15 may have, for example, a single-layer structure containing an adhesive component or a plurality of layers in which a layer containing an adhesive component is laminated on both surfaces of a sheet serving as a core material. It may have a structure.

A gap may exist between the release film 14 and the surface 23 a of the protective film forming film 23 or the surface 15 a of the jig adhesive layer 15. For example, in the surface 15 a of the jig adhesive layer 15, a region denoted by reference numeral 150 a (region on the side of the protective film forming film 23) and a region denoted by reference numeral 230 a in the surface 23 a of the protective film forming film 23. (The area on the side of the adhesive layer 15 for jig) easily forms the above-mentioned gap between the release film 14.
That is, in the vicinity of the boundary between the jig adhesive layer 15 and the protective film forming film 23 and in the region in contact with the release film 14, a void is easily generated.

  In the protective film forming composite sheet 2 shown in FIG. 2, the back surface of the semiconductor wafer (not shown) is attached to the front surface 23 a of the protective film forming film 23 in a state where the release film 14 is removed. The upper surface of the surface 15a of the adhesive layer 15 is used by being attached to a jig such as a ring frame.

FIG. 3 is a cross-sectional view schematically showing still another embodiment of the composite sheet for forming a protective film according to the present invention.
The composite sheet 3 for forming a protective film shown here has a two-layer structure in which a first pressure-sensitive adhesive layer 321 and a second pressure-sensitive adhesive layer 322 are laminated in this order from the substrate 11 instead of the pressure-sensitive adhesive layer 12. Except for having the agent layer 32, it is the same as the composite sheet 1 for forming a protective film shown in FIG.
When the protective sheet-forming composite sheet 3 is viewed from above and viewed from above, the second pressure-sensitive adhesive layer 322 has the same area as the protective-film-forming film 13, and the peripheral portion of the second adhesive layer 322 is the same as the protective-film-forming film 13. They are arranged to overlap. The protective film forming film 13 is provided on the surface 32 a of the pressure-sensitive adhesive layer 32 opposite to the substrate side (that is, the surface 322 a of the second pressure-sensitive adhesive layer 322). The first pressure-sensitive adhesive layer 321 is provided so as to cover the entire surface 11a of the base material 11, and when viewed in plan as described above, the first pressure-sensitive adhesive layer 321 is a second pressure-sensitive adhesive layer. The area is larger than 322.

In the composite sheet 3 for forming a protective film, the second pressure-sensitive adhesive layer 322 that is in contact with the film 13 for forming a protective film is formed from an alkyl (meth) acrylate having an alkyl group having 8 or more carbon atoms. It contains the (meth) acrylic acid alkyl ester copolymer having a derived structural unit. The first pressure-sensitive adhesive layer 321 that is not in contact with the protective film forming film 13 may or may not contain the (meth) acrylic acid alkyl ester copolymer.
That is, one side of the composite sheet for forming a protective film according to the present invention includes:
A substrate, a first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, a protective film-forming film, a jig adhesive layer, and a release film,
The first pressure-sensitive adhesive layer is provided on the base material so as to cover an upper surface of the base material,
The second pressure-sensitive adhesive layer is provided on the first pressure-sensitive adhesive layer,
The protective film forming film is provided on the second pressure-sensitive adhesive layer such that a peripheral portion of the second pressure-sensitive adhesive layer overlaps with the second pressure-sensitive adhesive layer,
The release film includes an upper surface and side surfaces of the protective film forming film, a side surface of the second adhesive layer, and a surface of the first adhesive layer on which the second adhesive layer is not laminated. It is laminated on,
When looking down and looking from above,
The second pressure-sensitive adhesive layer has the same area as the protective film-forming film,
The first pressure-sensitive adhesive layer has a larger area than the second pressure-sensitive adhesive layer,
The second pressure-sensitive adhesive layer has a structure in which the alkyl group constituting the alkyl ester has a structural unit derived from an alkyl (meth) acrylate having 8 to 18 carbon atoms. Containing coalescence,
It is a composite sheet for forming a protective film.

FIG. 4 is a cross-sectional view schematically illustrating still another embodiment of the composite sheet for forming a protective film according to the present invention.
The composite sheet 4 for forming a protective film shown here has a two-layer structure in which a first pressure-sensitive adhesive layer 421 and a second pressure-sensitive adhesive layer 422 are laminated in this order from the substrate 11 instead of the pressure-sensitive adhesive layer 12. It is the same as the protective film forming composite sheet 2 shown in FIG.
When the composite sheet 4 for forming a protective film is viewed from above and viewed from above, both the first pressure-sensitive adhesive layer 421 and the second pressure-sensitive adhesive layer 422 have the same area as the film 23 for forming a protective film.
The protective film forming film 23 is provided on the surface 42 a of the pressure-sensitive adhesive layer 42 (that is, the surface 422 a of the second pressure-sensitive adhesive layer 422).

In the composite sheet 4 for forming a protective film, the second pressure-sensitive adhesive layer 422 that is in contact with the film 23 for forming a protective film is formed from an alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group constituting the alkyl ester. It contains the (meth) acrylic acid alkyl ester copolymer having a derived structural unit. The first pressure-sensitive adhesive layer 421 not in contact with the protective film forming film 23 may or may not contain the (meth) acrylic acid alkyl ester copolymer.
That is, one side of the composite sheet for forming a protective film according to the present invention includes:
A substrate, a first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, a protective film-forming film, a jig adhesive layer, and a release film,
The first pressure-sensitive adhesive layer is laminated on the substrate,
The second pressure-sensitive adhesive layer is laminated on the first pressure-sensitive adhesive layer,
The protective film forming film is laminated on the second pressure-sensitive adhesive layer,
The jig adhesive layer is laminated on a part of the surface of the protective film forming film,
Of the surface of the protective film forming film, the exposed surface on which the jig adhesive layer is not laminated, and the upper surface and side surfaces of the jig adhesive layer, the release film is laminated,
When looking down and looking from above,
The first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer 422, and the protective film forming film 23 have the same area,
The second pressure-sensitive adhesive layer in contact with the protective film-forming film has a constitutional unit derived from an alkyl ester of (meth) acrylic acid having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester. Having the (meth) acrylic acid alkyl ester copolymer,
It is a composite sheet for forming a protective film.

The composite sheet for forming a protective film according to the present invention is not limited to those shown in FIGS. 1 to 4, and some configurations of those shown in FIGS. 1 to 4 may be changed or deleted within a range that does not impair the effects of the present invention. Or another configuration may be added to the configuration described above.
For example, in the protective film-forming composite sheet 3 shown in FIG. 3, when viewed from above and viewed from above, the second adhesive layer 322 has the same area as the protective film-forming film 13 and Although the area is smaller than the first pressure-sensitive adhesive layer 321, the area of the second pressure-sensitive adhesive layer 322 may not be the same as the area of the protective film forming film 13; May be large, and in this case, the second adhesive layer 322 may have the same area as the first adhesive layer 321.

  Further, in each of the protective film forming composite sheet 3 shown in FIG. 3 and the protective film forming composite sheet 4 shown in FIG. 4, the pressure-sensitive adhesive layer has a two-layer structure, but the pressure-sensitive adhesive layer has three or more layers. It may have a laminated structure. In this case, of the three or more pressure-sensitive adhesive layers, the layer that is in contact with the protective film-forming film (that is, the uppermost layer that is farthest from the base material in the thickness direction of the pressure-sensitive adhesive layer) is the aforementioned ( The (meth) acrylic acid alkyl ester copolymer is contained, and the other layers may or may not contain the (meth) acrylic acid alkyl ester copolymer.

  As will be described later in the examples, for the protective film-forming composite sheet having a size of 25 mm × 150 mm, the pressure-sensitive adhesive layer before curing was subjected to a peeling angle of 180 °, a temperature of 23 ° C., and a tensile speed of 300 mm / min. The peeling force (hereinafter sometimes referred to as “peeling force before curing of the pressure-sensitive adhesive layer”) measured as a load when peeled from the substrate is preferably 2000 mN / 25 mm or more, more preferably 2200 mN / 25 mm or more.

  Similarly, as described later in the examples, for the composite sheet for forming a protective film having a size of 25 mm × 150 mm, the pressure-sensitive adhesive layer after curing was peeled at an angle of 180 °, a temperature of 23 ° C., and a tensile speed of 300 mm / min. The peeling force (hereinafter, sometimes referred to as “peeling force after curing of the pressure-sensitive adhesive layer”) measured as a load when the film is peeled from the protective film is preferably 2000 mN / 25 mm or less, for example, 1700 mN / 25 mm or less. , 1200 mN / 25 mm or less, 700 mN / 25 mm or less, and the like.

  In the present invention, for the protective sheet-forming composite sheet having the above-mentioned size of 25 mm × 150 mm, the ratio of the peeling force before curing the adhesive layer to the peeling force after curing the adhesive layer ([peeling force before curing the adhesive layer] / [Peeling force after curing of pressure-sensitive adhesive layer]) is preferably 1.5 or more, 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 according to the present invention, for example, a pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition on a substrate, and a film for forming a protective film is formed from the composition for forming a protective film on the pressure-sensitive adhesive layer Can be produced.

  The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition to the surface of the substrate (the surface 11a of the substrate 11 in FIGS. 1 and 2) and drying the composition. At this time, if necessary, the applied pressure-sensitive adhesive composition may be crosslinked by heating. The heating condition is preferably, for example, 100 to 130 ° C. for 1 to 5 minutes, but is not limited thereto. Alternatively, the pressure-sensitive adhesive composition is applied to the surface of the release layer of the release material, and the pressure-sensitive adhesive layer formed by drying is bonded to the surface of the substrate, and the release material is removed to form the pressure-sensitive adhesive layer.

  Application of the pressure-sensitive adhesive composition to the surface of the substrate or the surface of the release layer of the release material may be performed by a known method, for example, an air knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a roll knife coater. , A curtain coater, a die coater, a knife coater, a screen coater, a Meyer bar coater, a kiss coater and the like.

  The film for forming a protective film can be formed from the composition for forming a protective film in the same manner as in forming the pressure-sensitive adhesive layer on the substrate as described above. It is difficult to apply the composition for use directly. Therefore, for example, a protective film forming composition is applied to the surface of the release layer of the release material, and the protective film formation film formed by drying is attached to the surface of the adhesive layer, and the release material is removed. A method in which a film for forming a protective film is separately formed and the film is bonded to the surface of the pressure-sensitive adhesive layer is preferable.

In addition, the composite sheet for forming a protective film according to the present invention may be, in addition to the above-described method, for example, forming a pressure-sensitive adhesive layer from the pressure-sensitive adhesive composition, and forming the protective film from the composition for forming a protective film. Is formed, the pressure-sensitive adhesive layer and the protective film-forming film are overlapped 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 protective film-forming film is not provided) It can also be manufactured by laminating a base material on the substrate.
The conditions for forming the pressure-sensitive adhesive layer and the film for forming a protective film in this case are the same as those described above.

  For example, when manufacturing a protective film forming composite sheet having a surface area smaller than the pressure-sensitive adhesive layer when the protective film forming composite sheet is viewed from above as viewed from above as shown in FIG. In the manufacturing method described above, a protective film-forming film cut into a predetermined size and shape in advance may be provided on the pressure-sensitive adhesive layer.

<Method of using composite sheet for forming protective film>
The method for using the composite sheet for forming a protective film according to the present invention is as follows.
That is, first, the back surface of the semiconductor wafer is attached to the protective film forming film of the protective film forming composite sheet, and the protective film forming composite sheet is fixed to a dicing apparatus.
Next, the protective film forming film is cured by heating (for example, heating at 130 ° C. for 2 hours) to form a protective film. When a back grinding tape is attached to the surface (electrode formation surface) of the semiconductor wafer, usually, the back grinding tape is removed from the semiconductor wafer, and then the protective film is formed.

  Next, the semiconductor wafer is diced into semiconductor chips. During the period from when the protective film is formed to when dicing is performed, the surface of the protective film can be printed by irradiating the protective film with laser light from the substrate side of the composite film for forming a protective film. In this case, as described above, since the peeling force between the pressure-sensitive adhesive layer and the protective film before curing is sufficiently large, even if gas is generated by laser printing, peeling between the pressure-sensitive adhesive layer and the protective film is suppressed. As a result, the occurrence of gas accumulation is suppressed. In addition, since the semiconductor wafer can be firmly and stably fixed on the composite sheet for forming a protective film, chip flying or the like can be suppressed during dicing, and dicing can be stably performed. When laser printing is performed, peeling of the adhesive layer and the protective film is suppressed as described above, and the occurrence of gas accumulation is also suppressed. It can be clearly and visually recognized through the pressure-sensitive adhesive layer.

  Next, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays (for example, ultraviolet rays, electron beams, or the like), and the semiconductor chip is peeled off from the cured pressure-sensitive adhesive layer together with the protective film attached to the back surface thereof to be picked up. By doing so, a semiconductor chip with a protective film is obtained. At this time, since the peeling force between the pressure-sensitive adhesive layer and the protective film after curing is sufficiently small, the semiconductor chip with the protective film can be stably and easily picked up, and the occurrence of cracks and chips in the pick-up is suppressed.

  For example, when the protective film forming composite sheet 1 shown in FIG. 1 is used, the back surface of the semiconductor wafer is attached to the protective film forming film 13 of the protective film forming composite sheet 1 and the exposed adhesive layer 12 is attached to a dicing jig (not shown) such as a ring frame, and the protective film forming composite sheet 1 is fixed to a dicing apparatus. Next, after the protective film forming film 13 is cured to form a protective film, dicing is performed, and by irradiating with active energy rays, a region of the pressure-sensitive adhesive layer 12 other than the position where the adhesive layer 12 is adhered to the jig is cured to protect the adhesive layer 12. What is necessary is just to pick up the semiconductor chip with a film. As described above, when the composite sheet 1 for forming a protective film is used, it is necessary to adjust the specific area of the pressure-sensitive adhesive layer 12 so as not to be separated from the jig. . On the other hand, when the composite sheet 1 for forming a protective film is used, there is no need to separately provide a configuration for attaching the composite sheet 1 to the jig.

  On the other hand, when the composite sheet 2 for forming a protective film shown in FIG. 2 is used, the back surface of the semiconductor wafer is affixed to the film 23 for forming the protective film of the composite sheet 2 for forming the protective film, and the adhesive layer 15 for the jig is formed. Is attached to a dicing jig (not shown) such as a ring frame, and the composite sheet 2 for forming a protective film is fixed to a dicing apparatus. Next, after the protective film forming film 23 is cured to form a protective film, dicing is performed, the adhesive layer 12 is cured by irradiation with active energy rays, and a semiconductor chip with a protective film may be picked up. As described above, when the composite sheet 2 for forming a protective film is used, unlike the case where the composite sheet 1 for forming a protective film is used, it is not necessary to adjust so as not to cure a specific region of the adhesive layer 23. It is. On the other hand, unlike the composite sheet 1 for forming a protective film, a composite sheet 2 having a jig adhesive layer 15 is required as the composite sheet 2 for forming a protective film. The provision of the jig adhesive layer 15 allows the pressure-sensitive adhesive layer 12 to have a wide range of compositions depending on the purpose.

As described above, the composite sheet for forming a protective film according to the present invention is a sheet suitable for curing the pressure-sensitive adhesive layer after curing the film for forming a protective film to form a protective film. When the semiconductor chip is picked up, the protective film forming film is completely or almost completely cured. The protective sheet-forming composite sheet according to the present invention has an effect that the peeling force between the pressure-sensitive adhesive layer and the protective film changes significantly before and after the pressure-sensitive adhesive layer is cured. This is because the pressure-sensitive adhesive layer contains a specific range of the alkyl (meth) acrylate copolymer as an essential component.
On the other hand, for example, in the case of the conventional protective film forming composite sheet described in the above-mentioned document “Japanese Patent Application Laid-Open No. 2011-228450” (Patent Document 1), when the semiconductor chip is picked up, the protective film is formed. The forming film remains in an uncured or partially cured state, and at the same time as bonding the semiconductor chip and curing with a sealing material, the uncured or partially cured protective film forming film is completely or almost completely cured. It is completely cured. That is, when using the conventional composite sheet for forming a protective film, at the stage of dicing a semiconductor wafer and picking up a semiconductor chip, a film (film) affixed to the back surface of the wafer and the chip according to the present invention is used. The properties are completely different from the ones. This document does not disclose any composition of the pressure-sensitive adhesive layer and the protective film forming film, which is suitable when the protective film forming film is cured before dicing.

Another aspect of the protective film forming composite sheet according to the present invention,
A substrate, a pressure-sensitive adhesive layer, a protective film forming composite sheet including a protective film forming film,
The pressure-sensitive adhesive layer is laminated on the base material, and the protective film forming film is laminated on the pressure-sensitive adhesive layer;
The pressure-sensitive adhesive layer,
Has active energy ray curability,
At least a layer in contact with the protective film forming film contains a (meth) acrylic acid alkyl ester copolymer,
The (meth) acrylic acid alkyl ester copolymer is a copolymer having a constitutional unit derived from an alkyl (meth) acrylate having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester;
The protective film-forming film has thermosetting properties;
After the composite sheet for forming a protective film is cut into a size of 25 mm × 150 mm, the composite sheet is formed on a silicon wafer at 70 ° C., and then the composite sheet for forming a protective film is heated at 130 ° C. for 2 hours. When the protective film is formed by curing the film for forming, the peeling force between the pressure-sensitive adhesive layer and the protective film before curing under the conditions of a peeling angle of 180 °, a measurement temperature of 23 ° C, and a tensile speed of 300 mm / min. The composite sheet for forming a protective film has a (peeling force before curing of the pressure-sensitive adhesive layer) of 2,000 mN / 25 mm or more, preferably 2300 mN / 25 mm or more and 6300 mN / 25 mm or less.
Further, when the protective sheet-forming composite sheet is irradiated with ultraviolet light under the conditions of an illuminance of 220 mW / cm ² and a light amount of 190 mJ / cm ² to cure the pressure-sensitive adhesive layer, Under the conditions of a peel angle of 180 °, a measurement temperature of 23 ° C., and a pulling speed of 300 mm / min, a peeling force (peeling force after curing of the pressure-sensitive adhesive layer) between the pressure-sensitive adhesive layer and the protective film after curing is 2,000 mN / 25 mm. Or less, preferably 500 mN / 25 mm or more and 1500 mN / 25 mm or less.

Another aspect of the protective film forming composite sheet according to the present invention,
A substrate, a pressure-sensitive adhesive layer, a protective film forming composite sheet including a protective film forming film,
The pressure-sensitive adhesive layer is laminated on the base material, and the protective film forming film is laminated on the pressure-sensitive adhesive layer;
The pressure-sensitive adhesive layer,
Has active energy ray curability,
At least the layer that is in contact with the protective film-forming film comprises a (meth) acrylic acid alkyl ester copolymer, an isocyanate-based cross-linking agent, a photopolymerization initiator, a solvent, and if desired, other components. Containing (meth) acrylic acid alkyl ester copolymer,
The (meth) acrylic acid alkyl ester copolymer is a copolymer having a structural unit derived from an alkyl (meth) acrylate having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester, Preferably at least one selected from the group consisting of 2-ethylhexyl acrylate, lauryl methacrylate and isostearyl acrylate;
The content of the constituent unit derived from the alkyl (meth) acrylate having 8 or more carbon atoms in the alkyl group is based on the total mass of all constituent units constituting the (meth) acrylic acid alkyl ester copolymer. From 30% by mass to 100% by mass, preferably from 35 to 85% by mass, more preferably from 40 to 80% by mass;
The protective film-forming film has thermosetting properties; and the polymer component (A),
Preferably acrylic resin, polyester, polyurethane, acrylic urethane resin, silicone resin, rubber polymer, and at least one selected from the group consisting of phenoxy resin,
More preferably an acrylic polymer;
Thermosetting component (B),
Preferably epoxy resin (B11) and thermosetting agent (B12),
More preferably, polyfunctional epoxy resin, biphenyl compound, bisphenol A diglycidyl ether and hydrogenated product thereof, orthocresol novolak epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin, bisphenol A type epoxy resin, bisphenol F At least one selected from the group consisting of a type epoxy resin, a phenylene skeleton type epoxy resin, and a bifunctional or higher functional epoxy compound, and an onium salt, a dibasic acid hydrazide, dicyandiamide, and an amine adduct of a curing agent. At least one,
Still more preferably, at least one selected from the group consisting of a bisphenol A type epoxy resin and a dicyclopentadiene type epoxy resin, and dicyandiamide;
A curing accelerator (C), preferably 2-phenyl-4,5-dihydroxymethylimidazole;
Optionally, at least one selected from the group consisting of a solvent, a filler (D), a coupling agent (E), a cross-linking agent (F), and a general-purpose additive (G);
Including;
After the composite sheet for forming a protective film is cut into a size of 25 mm × 150 mm, the composite sheet is formed on a silicon wafer at 70 ° C., and then the composite sheet for forming a protective film is heated at 130 ° C. for 2 hours. When the protective film is formed by curing the film for forming, the peeling force between the pressure-sensitive adhesive layer and the protective film before curing under the conditions of a peeling angle of 180 °, a measurement temperature of 23 ° C, and a tensile speed of 300 mm / min. The composite sheet for forming a protective film has a (peeling force before curing of the pressure-sensitive adhesive layer) of 2,000 mN / 25 mm or more, preferably 2300 mN / 25 mm or more and 6300 mN / 25 mm or less.
Further, when the protective sheet-forming composite sheet is irradiated with ultraviolet light under the conditions of an illuminance of 220 mW / cm ² and a light amount of 190 mJ / cm ² to cure the pressure-sensitive adhesive layer, Under the conditions of a peel angle of 180 °, a measurement temperature of 23 ° C., and a pulling speed of 300 mm / min, a peeling force (peeling force after curing of the pressure-sensitive adhesive layer) between the pressure-sensitive adhesive layer and the protective film after curing is 2,000 mN / 25 mm. Or less, preferably 500 mN / 25 mm or more and 1500 mN / 25 mm or less.

Another aspect of the invention is:
For the production of a semiconductor chip with a protective film, the use of a composite sheet for forming a protective film, wherein the composite sheet for forming a protective film includes a substrate, an adhesive layer, and a film for forming a protective film,
The pressure-sensitive adhesive layer is laminated on the base material, and the protective film forming film is laminated on the pressure-sensitive adhesive layer;
The pressure-sensitive adhesive layer,
Has active energy ray curability,
At least a layer in contact with the protective film forming film contains a (meth) acrylic acid alkyl ester copolymer,
The (meth) acrylic acid alkyl ester copolymer is a copolymer having a constitutional unit derived from an alkyl (meth) acrylate having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester;
The protective film-forming film has thermosetting properties;
After the composite sheet for forming a protective film is cut into a size of 25 mm × 150 mm, the composite sheet is formed on a silicon wafer at 70 ° C., and then the composite sheet for forming a protective film is heated at 130 ° C. for 2 hours. When the protective film is formed by curing the film for forming, the peeling force between the pressure-sensitive adhesive layer and the protective film before curing under the conditions of 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 pressure-sensitive adhesive layer) is 2,000 mN / 25 mm or more, preferably 2300 mN / 25 mm or more and 6300 mN / 25 mm or less.
This is the use of the composite sheet for forming a protective film.
Further, when the protective sheet-forming composite sheet is irradiated with ultraviolet light under the conditions of an illuminance of 220 mW / cm ² and a light amount of 190 mJ / cm ² to cure the pressure-sensitive adhesive layer, Under the conditions of a peel angle of 180 °, a measurement temperature of 23 ° C., and a pulling speed of 300 mm / min, the peeling force between the pressure-sensitive adhesive layer and the protective film after curing (peeling force after curing the pressure-sensitive adhesive layer) is 2000 mN / 25 mm Or less, preferably 500 mN / 25 mm or more and 1500 mN / 25 mm or less.

A method for manufacturing a semiconductor chip with a protective film,
The manufacturing method comprises:
Affixing the protective film forming composite sheet to the back surface of the semiconductor wafer by the protective film forming film,
The protective film forming film in the attached protective film forming composite sheet is cured by heating to form a protective film,
Dicing the semiconductor wafer on which the protective film is formed into semiconductor chips, and curing the pressure-sensitive adhesive layer in the composite sheet for protective film formation by irradiation with active energy rays, and then applying the adhesive to the back surface of the semiconductor chip. Picking up the semiconductor chip together with the formed protective film;
The composite sheet for forming a protective film includes a base material, the pressure-sensitive adhesive layer, and the film for forming a protective film, wherein the pressure-sensitive adhesive layer is laminated on the base material, and the film for forming a protective film is formed. Is laminated on the pressure-sensitive adhesive layer;
The pressure-sensitive adhesive layer,
Has active energy ray curability,
At least a layer in contact with the protective film forming film contains a (meth) acrylic acid alkyl ester copolymer,
The (meth) acrylic acid alkyl ester copolymer is a copolymer having a constitutional unit derived from an alkyl (meth) acrylate having 8 to 18 carbon atoms in an alkyl group constituting the alkyl ester;
The protective film forming film has thermosetting properties,
This is a method for manufacturing a semiconductor chip with a protective film.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples described below.

[Example 1]
<Production of composite sheet for forming protective film>
A composite sheet for forming a protective film having the configuration shown in FIG. 1 was manufactured. More specifically, it is as follows.

[Production of support sheet (formation of adhesive layer)]
An adhesive composition is applied on one surface of a polypropylene film (thickness: 80 μm, manufactured by Mitsubishi Plastics) as a base material, and dried to form an ultraviolet-curable adhesive layer (thickness: 10 μm). Thus, a support sheet was obtained. The pressure-sensitive adhesive composition has 6.6 parts by mass of 100 parts by mass (solid content) of a (meth) acrylic acid alkyl ester copolymer and a trifunctional xylylene diisocyanate-based crosslinking agent ("Takenate D110N" manufactured by Mitsui Takeda Chemical Co., Ltd.) Solid content), and 3.0 parts by mass (solid content) of a photopolymerization initiator (“IRGACURE 127” manufactured by BASF), and a solid content concentration of 30 mass% using a mixed solvent of methyl ethyl ketone, toluene and ethyl acetate. It is adjusted to%. The alkyl (meth) acrylate copolymer is composed of 80 parts by mass of 2-ethylhexyl acrylate (hereinafter, may be abbreviated as “2EHA”) and 2-hydroxyethyl acrylate (hereinafter, “HEA”). 20 parts by mass), and further added to 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate; hereinafter, abbreviated as "MOI") to a pre-copolymer obtained by copolymerizing 20 parts by mass of 21.4 parts by mass (the amount by which the total number of moles of isocyanate groups in 2-methacryloyloxyethyl isocyanate is 0.8 times the total number of moles of hydroxyl groups in HEA). Further, it is an ultraviolet curable acrylic copolymer having a weight average molecular weight of 1100000. Table 1 shows the amounts of the monomer components when the alkyl (meth) acrylate copolymer was produced. In Table 1, "-" in the column of the monomer component means that the monomer component is not blended.

[Production of composite sheet for forming protective film (formation of film for forming protective film)]
A composition for forming a protective film is applied to the release-treated surface of a release film (“SP-PET381031” manufactured by Lintec, 38 μm in thickness), in which one side of a polyethylene terephthalate film is subjected to a release treatment by silicone treatment, and dried. Then, a protective film forming film (thickness: 25 μm) was formed. In the composition for forming a protective film, the following components were blended in the amounts (solid contents) shown in Table 2, and the solid content concentration was adjusted to 55% by mass using a mixed solvent of methyl ethyl ketone, toluene and ethyl acetate. Things.
Then, the protective film-forming film is attached to the surface of the pressure-sensitive adhesive layer of the support sheet obtained above, whereby the surface of the protective film-forming film opposite to the side on which the pressure-sensitive adhesive layer is provided is provided. To obtain a composite sheet for forming a protective film provided with the 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: 370000, 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 184 to 194 g / eq)
(B11) -2: Bisphenol A type epoxy resin ("jER1055" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 800 to 900 g / eq)
(B11) -3: Dicyclopentadiene type epoxy resin ("Epiclon HP-7200HH" manufactured by DIC, epoxy equivalent 255 to 260 g / eq)
・ Thermosetting agent (B12)
(B12) -1: Dicyandiamide (solid dispersion type latent curing agent, “ADEKA HARDNER EH-3636AS” manufactured by ADEKA, active hydrogen amount 21 g / eq)
(Curing accelerator (C))
(C) -1: 2-phenyl-4,5-dihydroxymethylimidazole (“Curesol 2PHZ” manufactured by Shikoku Chemicals)
(Filler (D))
(D) -1: Silica filler (Admatex “SC2050MA”, average particle size 0.5 μm)
(Coupling agent (E))
(E) -1: Silane coupling agent (“A-1110” manufactured by Nihon Uny Corporation)
(General purpose additive (G))
(G) -1: carbon black (colorant, “# MA650” manufactured by Mitsubishi Chemical Corporation, average particle size 28 nm)

<Evaluation of composite sheet for forming protective film>
[Suppression of chip fly during dicing]
After removing the release film from the composite film for forming a protective film obtained above, the exposed film for forming a protective film is adhered to a dry-polished surface of a silicon wafer (diameter 6 inches, thickness 100 μm) at 70 ° C. At the same time, the exposed pressure-sensitive adhesive layer was attached to a ring frame, and left still for 30 minutes.
Next, 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, the silicon wafer was diced into a size of 5 mm × 5 mm using a dicing apparatus to obtain chips. At this time, the presence or absence of a chip jump was visually checked. The case where there was no chip jump was “A”, and the case where there was one or more chip jump was “B”. Table 3 shows the results.

[Pickup property]
After removing the release film from the composite film for forming a protective film obtained above, the exposed film for forming a protective film is adhered to a dry-polished surface of a silicon wafer (diameter 6 inches, thickness 100 μm) at 70 ° C. At the same time, the exposed pressure-sensitive adhesive layer was attached to a ring frame, and left still for 30 minutes.
Next, 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, the silicon wafer was diced into a size of 5 mm × 5 mm using a dicing apparatus to obtain chips. The light source using an ultraviolet irradiation apparatus (manufactured by LINTEC Corporation "RAD2000m / 8"), illuminance 220 mW / cm ^2, under conditions of light quantity 190 mJ / cm ^2, the composite sheet for forming a protective film from the substrate side, a high pressure mercury lamp To cure the pressure-sensitive adhesive layer.
Then, using a die bonder (“BESTEM-D02” manufactured by Canon Machinery Co., Ltd.), 20 chips were picked up, and when there was no chip in which cracks or chips occurred, “A” was assigned. The case where one or more chips occurred was designated as "B". Table 3 shows the results.

[Peeling force between adhesive layer and protective film before curing]
After the composite sheet for forming a protective film obtained above is cut into a size of 25 mm x 150 mm, the release film is removed, and the exposed film for forming a protective film is exposed using a laminator ("LAMIPACKERLP3214" manufactured by Fuji Co., Ltd.). Then, it was attached at 70 ° C. to a dry-polished surface of a silicon wafer (diameter 6 inches, thickness 500 μm).
Next, the composite film 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).
Using a precision universal testing machine ("Autograph AG-IS" manufactured by Shimadzu Corporation), the test piece (1) was subjected to a support sheet (curing) at a peeling angle of 180 °, a measuring temperature of 23 ° C, and a tensile speed of 300 mm / min. A tensile test is performed to peel the previous adhesive layer and the base material) from the protective film, and the load at this time is measured, and the peeling force between the adhesive layer and the protective film before curing (the adhesive before curing) As the measured values of the load, the measured values obtained when the support sheet was peeled over a length of 100 mm, when the support sheet was first peeled off by 10 mm, and finally when the support sheet was peeled over a length of 100 mm, The value obtained by excluding each measurement value from the effective value when peeled off by 10 mm was adopted.
Table 3 shows the results. The results correspond to the values of “Before the pressure-sensitive adhesive layer is cured” in the column of “Peeling force (mN / 25 mm)” in Table 3.

[Peeling force between pressure-sensitive adhesive layer and protective film after curing]
The same test piece (1) as above was prepared.
Then, a light source using an ultraviolet irradiation apparatus (manufactured by LINTEC Corporation "RAD2000m / 8"), illuminance 220 mW / cm ^2, under conditions of light quantity 190 mJ / cm ^2, the composite sheet for forming a protective film from the substrate side, a high pressure mercury lamp Then, the pressure-sensitive adhesive layer was cured by irradiating ultraviolet rays to prepare a test piece (2).
This test piece (2) was subjected to a tensile test in which the support sheet (laminated body of the cured pressure-sensitive adhesive layer and the base material) was peeled off from the protective film in the same manner as in the case of the test piece (1), and cured. The peeling force between the pressure-sensitive adhesive layer and the protective film afterward (the pressure-sensitive adhesive layer peeling force after curing). Table 3 shows the results. The results correspond to the numerical value of “after curing of the pressure-sensitive adhesive layer” in the column of “peeling force (mN / 25 mm)” in Table 3.

<Production and evaluation of composite sheet for forming protective film>
[Example 2]
At the time of forming the pressure-sensitive adhesive layer, as shown in Table 1, 40 mass parts of 2EHA and vinyl acetate (hereinafter, referred to as “methacrylic acid alkyl ester copolymer”) were used instead of the above-mentioned one having a weight average molecular weight of 1100000. VAc ") and 40 parts by mass of HEA were copolymerized with 20 parts by mass of HEA, and further, 21.4 parts by mass of MOI (based on the total moles of hydroxyl groups in HEA) Example 1 except that an ultraviolet-curable acrylic copolymer having a weight average molecular weight of 500,000 obtained by reacting the same was used to make the total number of moles of isocyanate groups in the MOI 0.8 times). A composite sheet for forming a protective film was produced and evaluated in the same manner as described above. Table 3 shows the results.

[Example 3]
When forming the pressure-sensitive adhesive layer, as shown in Table 1, lauryl methacrylate (hereinafter abbreviated as "LMA") as shown in Table 1 instead of the above-mentioned alkyl (meth) acrylate copolymer having a weight average molecular weight of 1100000. To the pre-copolymer obtained by copolymerizing 80 parts by mass of 20 parts by mass of HEA and 21.4 parts by mass of MOI (to the total number of moles of hydroxyl groups in HEA, The same method as in Example 1 except that an ultraviolet-curable acrylic copolymer having a weight average molecular weight of 600,000 and obtained by reacting the same with the total number of moles of isocyanate groups 0.8 times) was used. And a composite sheet for forming a protective film was manufactured and evaluated. Table 3 shows the results.

[Example 4]
When forming the pressure-sensitive adhesive layer, as shown in Table 1, instead of the above (meth) acrylic acid alkyl ester copolymer having a weight average molecular weight of 1100000, as shown in Table 1, isostearyl acrylate (hereinafter referred to as "ISTA") The pre-copolymer obtained by copolymerizing 80 parts by mass of 80 parts by mass of HEA and 20 parts by mass of HEA was further added with 21.4 parts by mass of MOI (to the total number of moles of hydroxyl group in HEA, In the same manner as in Example 1 except that an ultraviolet-curable acrylic copolymer having a weight average molecular weight of 600,000 obtained by reacting the same was used. Then, a composite sheet for forming a protective film was manufactured and evaluated. Table 3 shows the results.

[Comparative Example 1]
At the time of forming the pressure-sensitive adhesive layer, as shown in Table 1, butyl acrylate (hereinafter abbreviated as “BA”) is used as the alkyl (meth) acrylate copolymer instead of the above-mentioned one having a weight average molecular weight of 1100000. 40 parts by mass), 40 parts by mass of VAc, and 20 parts by mass of HEA were further copolymerized with a precopolymer obtained by adding 21.4 parts by mass of MOI (based on the total number of moles of hydroxyl groups in HEA). Except that an ultraviolet-curable acrylic copolymer having a weight-average molecular weight of 600,000 was obtained by reacting the resulting copolymer with an amount such that the total number of moles of isocyanate groups in the MOI becomes 0.8 times. In the same manner as in Example 1, a composite sheet for forming a protective film was produced and evaluated. Table 3 shows the results.

[Comparative Example 2]
At the time of forming the pressure-sensitive adhesive layer, as shown in Table 1, instead of the above (meth) acrylic acid alkyl ester copolymer having a weight average molecular weight of 1100000, 40 parts by mass of BA and methyl methacrylate (hereinafter, referred to as A pre-copolymer obtained by copolymerizing 40 parts by mass of “MMA” and 20 parts by mass of HEA was further added with 21.4 parts by mass of MOI (based on the total number of moles of hydroxyl groups in HEA). Except that an ultraviolet-curable acrylic copolymer having a weight-average molecular weight of 600,000 was obtained by reacting the resulting copolymer with an amount such that the total number of moles of isocyanate groups in the MOI becomes 0.8 times. In the same manner as in Example 1, a composite sheet for forming a protective film was produced and evaluated. Table 3 shows the results.

When the composite sheet for forming a protective film of Examples 1 to 4 was used, the (meth) acrylic acid alkyl ester copolymer was such that the alkyl group constituting the alkyl ester had a carbon number of 8 or more (meth). By having a structural unit derived from an alkyl acrylate, the peeling force between the pressure-sensitive adhesive layer and the protective film before curing is sufficiently large, so that dicing can be performed stably, and after curing. The peeling force between the pressure-sensitive adhesive layer and the protective film was sufficiently small, and the semiconductor chip could be stably picked up.
The ratio of the peeling force before and after the curing of the pressure-sensitive adhesive layer ([peeling force before curing the pressure-sensitive adhesive layer] / [peeling force after curing the pressure-sensitive adhesive layer]) was 4.6 in Example 1, 4.2 in Example 2, Example 3 is 14.3 and Example 4 is 1.8, which is particularly large in Examples 1 to 3. Among them, Example 3 is remarkably large, and the alkyl group constituting the alkyl ester is particularly large. It is suggested that the effect of the present invention is particularly enhanced when the number of carbon atoms is 12 and a value in the vicinity thereof.

  On the other hand, when the composite sheet for forming a protective film of Comparative Examples 1 and 2 was used, the (meth) acrylic acid alkyl ester copolymer was such that the alkyl group constituting the alkyl ester had 8 carbon atoms. By not having the structural unit derived from the above alkyl (meth) acrylate, the peeling force between the pressure-sensitive adhesive layer and the protective film before curing is sufficiently large, and stable dicing can be performed. However, the peeling force between the pressure-sensitive adhesive layer and the protective film after curing was not sufficiently reduced, and the semiconductor chip could not be stably picked up.

  INDUSTRIAL APPLICABILITY The present invention is very useful industrially because it can be used for manufacturing a semiconductor chip or the like whose back surface is protected by a protective film.

  1, 2, 3, 4 ... composite sheet for forming a protective film, 10 ... support sheet, 11 ... substrate, 11a ... surface of substrate, 12, 32, 42 ... adhesive Layers, 12a, 32a, 42a: Surface of adhesive layer, 321, 421: First adhesive layer, 322, 422: Second adhesive layer, 322a, 422a: Second adhesive Surfaces of layers, 13, 23: Film for forming protective film, 13a, 23a: Surface of film for forming protective film, 14: Release film, 15: Adhesive layer for jig, 15a ..Surface of adhesive layer for jig

Claims (3)

A pressure-sensitive adhesive layer is provided on a substrate, and a protective film-forming film is provided on the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer has an active energy ray-curable property, and the protective film-forming film has a thermosetting property. A composite sheet for forming a protective film having:
After the protective film forming composite sheet is attached to the back surface of the semiconductor wafer with the protective film forming film, the protective film forming film is cured by heating to form a protective film, and then the semiconductor wafer is diced. After forming a semiconductor chip, the pressure-sensitive adhesive layer is cured by irradiation with active energy rays, and then the semiconductor chip is picked up together with the protective film attached to the back surface of the semiconductor chip, thereby manufacturing a semiconductor chip with a protective film. Is used to
The pressure-sensitive adhesive layer contains a (meth) alkyl acrylate copolymer at least in a layer in contact with the protective film-forming film,
The (meth) acrylic acid alkyl ester copolymer has a structural unit derived from an alkyl (meth) acrylate having 8 or more carbon atoms in an alkyl group constituting the alkyl ester,
When the pressure-sensitive adhesive layer is used as a photopolymerization initiator, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one is used. And a composite sheet for forming a protective film.   The protective film formation according to claim 1, wherein the film for forming a protective film contains an epoxy resin, a thermosetting agent that is dissolved by heating and has a curing activity for the epoxy resin, and an imidazole. For composite sheet.   The protective sheet-forming composite sheet according to claim 1, wherein the alkyl group constituting the alkyl ester has 11 to 18 carbon atoms.

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