JPWO2019008809A1 - Stealth dicing adhesive sheet and method for manufacturing semiconductor device - Google Patents

Abstract

At least a stealth dicing pressure-sensitive adhesive sheet 1 used for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment. And a pressure-sensitive adhesive layer 12 laminated on the surface of the silicon wafer, and when the stealth dicing pressure-sensitive adhesive sheet 1 is attached to a silicon wafer through the pressure-sensitive adhesive layer 12, the interface 23 between the pressure-sensitive adhesive layer 12 and the silicon wafer is A pressure-sensitive adhesive sheet 1 for stealth dicing, which has a shearing force at 5 ° C. of 5 N / (3 mm × 20 mm) or more and 70 N / (3 mm × 20 mm) or less. The stealth dicing pressure-sensitive adhesive sheet 1 has excellent chip cleaning properties.

Description

  The present invention relates to an adhesive sheet for stealth dicing used for stealth dicing (registered trademark) processing, and a method for manufacturing a semiconductor device using the adhesive sheet for stealth dicing.

  BACKGROUND ART When manufacturing a chip-shaped semiconductor device from a semiconductor wafer, conventionally, a blade dicing process for cutting the semiconductor wafer with a rotary blade to obtain chips while spraying a liquid for cleaning or the like on the semiconductor wafer has been performed. It was common. However, in recent years, a stealth dicing process that can be divided into chips by a dry method has been adopted. In the stealth dicing process, as an example, a semiconductor wafer attached to a dicing sheet is irradiated with a laser beam having a large opening degree (NA) so that damage near the surface of the semiconductor wafer is minimized and the inside of the semiconductor wafer is preliminarily protected. A modified layer is formed. Then, by expanding the dicing sheet, a force is applied to the semiconductor wafer to cut into individual chips.

  In recent years, it has been required to stack another chip on the chip manufactured as described above or to bond the chip to a film substrate. Then, from the face-up type mounting in which the circuit of the chip and the circuit on another chip or the substrate are connected by a wire, the electrode formation surface of the chip provided with the protruding electrodes and the circuit on the other chip or the substrate In some fields, flip chip mounting, in which the electrodes are opposed to each other and the electrodes are directly connected to each other, and the transition to the Through Silicon Via (TSV) is performed. In order to meet the demands for stacking and bonding chips in flip chip mounting and the like, there has been proposed a method of fixing an electrode-equipped chip to another chip or a film substrate using an adhesive.

  Then, in order to be easily applied to such an application, in the process of the above manufacturing method, with respect to the electrode-equipped semiconductor wafer or the electrode-modified semiconductor wafer having the dicing sheet attached to the surface opposite to the electrode formation surface, It has been proposed that a film-like adhesive is laminated on the electrode forming surface, and the chip with electrodes divided by the expanding step is provided with an adhesive layer on the electrode forming surface. As such an adhesive layer, an adhesive film called a die attach film (DAF) or a non-conductive adhesive film (NCF) is used.

  Patent Document 1 discloses that DAF is attached to a wafer, stealth dicing is performed, and then the wafer is divided into chips by expanding and at the same time DAF is divided.

JP, 2005-19962, A

  By the way, in the above-mentioned stealth dicing process, when the semiconductor wafer is cut and separated in the modified layer, crushed pieces mainly originating from the modified layer are generated, and the crushed pieces may adhere to the chip. Therefore, the chips are washed to remove the crushed pieces.

  Cleaning of such chips may be performed on the dicing sheet. That is, after dicing the semiconductor wafer into chips on the dicing sheet, cleaning is performed while the obtained chips are stacked on the dicing sheet. In this case, by expanding the dicing sheet to widen the interval between chips (chip interval), better cleaning of chips becomes possible.

  However, since the conventional dicing sheet used in the method disclosed in Patent Document 1 cannot be expanded sufficiently, it is difficult to sufficiently widen the chip interval and perform good cleaning.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a pressure-sensitive adhesive sheet for stealth dicing and a method for manufacturing a semiconductor device, which are excellent in chip cleanability.

  In order to achieve the above-mentioned object, firstly, the present invention relates to a pressure-sensitive adhesive sheet for stealth dicing used for cutting and separating at least a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment. In the case of including a base material and a pressure-sensitive adhesive layer laminated on one surface side of the base material, when the stealth dicing pressure-sensitive adhesive sheet is attached to a silicon wafer via the pressure-sensitive adhesive layer, Provided is a pressure-sensitive adhesive sheet for stealth dicing, wherein the shearing force at the interface between the pressure-sensitive adhesive layer and the silicon wafer at 23 ° C. is 5 N / (3 mm × 20 mm) or more and 70 N / (3 mm × 20 mm) or less. Yes (Invention 1).

  In the pressure-sensitive adhesive sheet for stealth dicing according to the above invention (Invention 1), when the shearing force at 23 ° C is within the above range, the chips can be satisfactorily expanded in a stacked state. Therefore, the chip interval can be sufficiently widened when cleaning the chips, and as a result, the chips can be cleaned well.

  In the said invention (invention 1), it is preferable that the said adhesive layer is comprised from an energy ray curable adhesive (invention 2).

  In the above inventions (Inventions 1 and 2), the storage elastic modulus at 23 ° C. of the base material is preferably 10 MPa or more and 600 MPa or less (Invention 3).

  Secondly, the present invention relates to a bonding step for bonding the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing (Invention 1 to 3) and a semiconductor wafer, and a modification step of forming a modified layer inside the semiconductor wafer. Quality layer forming step, by expanding the adhesive sheet for stealth dicing in a room temperature environment, an expanding step of cutting and separating the semiconductor wafer in which the modified layer is formed into individual chips, and the adhesive for stealth dicing And a cleaning step of cleaning the chip laminated on the stealth dicing pressure-sensitive adhesive sheet in a state where the sheet is expanded (Invention 4).

  In the said invention (invention 4), the lamination process which laminates | stacks an adhesive film on the surface on the opposite side to the said adhesive sheet side for stealth dicing in the said semiconductor wafer bonded by the adhesive sheet for stealth dicing is further provided. It is preferable (Invention 5).

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet for stealth dicing which was excellent in the washability of a chip, and the manufacturing method of a semiconductor device are provided.

It is a top view explaining the measuring method of the shearing force concerning test example 1. It is sectional drawing explaining the measuring method of the shearing force which concerns on test example 1.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet for stealth dicing]
The pressure-sensitive adhesive sheet for stealth dicing according to one embodiment of the present invention is used for cutting and separating at least a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment. Here, the room temperature environment means, for example, an environment of 5 ° C. or higher, particularly preferably an environment of 10 ° C. or higher, and more preferably an environment of 15 ° C. or higher. Further, the room temperature environment means, for example, an environment of 45 ° C. or lower, particularly preferably an environment of 40 ° C. or lower, and more preferably an environment of 35 ° C. or lower. Since the above temperature range is easily achieved without intentionally controlling the temperature, stealth dicing cost can be reduced. It should be noted that the concept of “tape” is included in “sheet” in this specification.

  The adhesive sheet for stealth dicing according to this embodiment includes a base material and an adhesive layer laminated on one surface side of the base material. The base material and the pressure-sensitive adhesive layer are preferably laminated directly, but are not limited thereto.

  When the stealth dicing pressure-sensitive adhesive sheet is attached to a silicon wafer through the pressure-sensitive adhesive layer of the stealth dicing pressure-sensitive adhesive sheet according to the present embodiment, the shearing force at the interface between the pressure-sensitive adhesive layer and the silicon wafer at 23 ° C. is 5 N / (3 mm × 20 mm) or more and 70 N / (3 mm × 20 mm) or less.

  Stealth dicing pressure-sensitive adhesive sheet according to the present embodiment, by having a shearing force as described above, is stuck to the stealth dicing pressure-sensitive adhesive sheet, a semiconductor wafer having a modified layer formed therein, at room temperature. By expanding under an environment, the chips can be cut and separated into individual chips, and then the chip intervals can be sufficiently widened. Specifically, the chip interval (distance between side faces of adjacent chips) can be expanded to about 150 to 300 μm, preferably about 155 to 260 μm, and particularly preferably about 160 to 250 μm. When the chip interval is extended to such a distance, when cleaning the chips, the cleaning liquid easily enters between the chips, and the fragments generated by cutting and separating the semiconductor wafer are effectively removed from the chips. It becomes possible. The method for measuring the shearing force is as shown in the test example described later.

  When the shearing force is less than 5 N / (3 mm × 20 mm), when the shearing force is applied to the portion where the adhesive sheet for stealth dicing and the ring frame are in close contact during expansion, the adhesive sheet for stealth dicing falls off from the ring frame. It cannot be used stably because it is likely to occur. On the other hand, if the shearing force exceeds 70 N / (3 mm × 20 mm), the chip interval cannot be expanded to a distance sufficient for good cleaning.

  From the above viewpoints, the lower limit of the shearing force is preferably 10 N / (3 mm × 20 mm) or more, and particularly preferably 13 N / (3 mm × 20 mm) or more. Further, the upper limit value of the shearing force is preferably 65 N / (3 mm × 20 mm) or less, and particularly preferably 60 N / (3 mm × 20 mm) or less.

  In the adhesive sheet for stealth dicing according to this embodiment, the chip interval can be maintained at an appropriate distance even after the expanded state is released. Specifically, the chip interval after opening can be maintained at about 50 to 200 μm. By maintaining the chip interval at such a distance, it is possible to prevent the chips from colliding with each other after opening.

1. Adhesive Layer The adhesive layer of the adhesive sheet for stealth dicing according to the present embodiment is not particularly limited as long as it satisfies the above shearing force. The adhesive layer may be composed of a non-energy ray curable adhesive or an energy ray curable adhesive. As the non-energy ray-curable pressure-sensitive adhesive, those having desired adhesive strength and removability are preferable, for example, acrylic pressure-sensitive adhesive, rubber pressure-sensitive adhesive, silicone pressure-sensitive adhesive, urethane pressure-sensitive adhesive, polyester pressure-sensitive adhesive. A polyvinyl ether-based pressure-sensitive adhesive or the like can be used. Among these, an acrylic pressure-sensitive adhesive that can effectively prevent the semiconductor wafer, the chip, and the like from falling off in the modified layer forming step, the expanding step, and the like is preferable.

  On the other hand, the energy ray-curable pressure-sensitive adhesive is cured by irradiation with energy rays and its adhesive strength is reduced. Therefore, when it is desired to separate the chips obtained by dividing the semiconductor wafer from the pressure-sensitive adhesive sheet for stealth dicing, It can be easily separated by irradiation.

  The energy ray-curable pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer may contain a polymer having an energy ray-curable property as a main component, or a non-energy ray-curable polymer (a polymer that does not have an energy ray-curable property). The main component may be a mixture of a monomer and / or an oligomer having at least one energy ray-curable group. Further, it may be a mixture of a polymer having energy ray curability and a non-energy ray curable polymer, a polymer having energy ray curability and a monomer having at least one or more energy ray curable groups, and / or It may be a mixture with an oligomer or a mixture of these three kinds.

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

  The energy ray-curable polymer is a (meth) acrylic acid ester (co) polymer (A) (hereinafter referred to as "energy ray-curable group" in which a functional group (energy ray-curable group) having energy ray-curable property is introduced into a side chain. It may be referred to as “curable polymer (A)”). This energy ray-curable polymer (A) is obtained by reacting an acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group. It is preferably obtained by In addition, in this specification, a (meth) acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. The same applies to other similar terms.

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

  The functional group-containing monomer as a constitutional unit of the acrylic copolymer (a1) has a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, a substituted amino group or an epoxy group in the molecule. It is preferable that the monomer has

  Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-hydroxybutyl ( Examples thereof include (meth) acrylate and 4-hydroxybutyl (meth) acrylate, which may be used alone or in combination of two or more kinds.

  Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer or the substituted amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

  As the (meth) acrylic acid ester monomer constituting the acrylic copolymer (a1), in addition to an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms, for example, an alicyclic structure is included in the molecule. The monomer (monomer having alicyclic structure) having is preferably used.

  As the alkyl (meth) acrylate, an alkyl (meth) acrylate whose alkyl group has 1 to 18 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl ( (Meth) acrylate, 2-ethylhexyl (meth) acrylate and the like are preferably used. These may be used alone or in combination of two or more.

  Examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentenyl (meth) acrylate. , And dicyclopentenyloxyethyl (meth) acrylate are preferably used. These may be used alone or in combination of two or more.

  The acrylic copolymer (a1) contains the structural unit derived from the functional group-containing monomer in an amount of preferably 1 to 35% by mass, particularly preferably 5 to 30% by mass, and further preferably 10 to 25% by mass. contains. The acrylic copolymer (a1) is preferably 50 to 99% by mass, particularly preferably 60 to 95% by mass, further preferably 70% by mass of the structural unit derived from the (meth) acrylic acid ester monomer or its derivative. It is contained in a proportion of 90 mass%.

  The acrylic copolymer (a1) can be obtained by copolymerizing a functional group-containing monomer as described above and a (meth) acrylic acid ester monomer or a derivative thereof by a conventional method. Dimethyl acrylamide, vinyl formate, vinyl acetate, styrene, etc. may be copolymerized.

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

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

  The unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6 and more preferably 1 to 4 energy ray-polymerizable carbon-carbon double bonds in one molecule. ing. Specific examples of the unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1- ( Bisacryloyloxymethyl) ethyl isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound and hydroxyethyl (meth) acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, hydroxyethyl (meth) Acryloyl monoisocyanate compound obtained by reaction with acrylate; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1 -Aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline and the like.

  The unsaturated group-containing compound (a2) is preferably 50 to 95 mol%, particularly preferably 60 to 93 mol%, and further preferably based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). It is used in a proportion of 70 to 90 mol%.

  In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2) Depending on the combination, the reaction temperature, pressure, solvent, time, presence or absence of catalyst, and type of catalyst can be appropriately selected. As a result, the functional group present in the acrylic copolymer (a1) reacts with the functional group in the unsaturated group-containing compound (a2), and the unsaturated group is replaced by the functional group in the acrylic copolymer (a1). It is introduced into the side chain to obtain the energy ray-curable polymer (A).

  The weight average molecular weight (Mw) of the energy ray-curable polymer (A) thus obtained is preferably 10,000 or more, particularly preferably 150,000 to 1,500,000, and further 200,000 to 100. It is preferable that it is ten thousand. In addition, the weight average molecular weight (Mw) in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography method (GPC method).

  Even when the energy ray-curable pressure-sensitive adhesive has a polymer having an energy ray-curable property such as the energy ray-curable polymer (A) as a main component, the energy ray-curable pressure-sensitive adhesive is an energy ray-curable monomer. And / or the oligomer (B) may be further contained.

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

  Examples of such energy ray-curable monomers and / or oligomers (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, penta Erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol Polyfunctional acrylic acid esters such as di (meth) acrylate, dimethyloltricyclodecanedi (meth) acrylate, polyester oligo (meth) acrylate, polyurethane oligo (meth) Acrylate, and the like.

  When the energy ray-curable polymer (A) is blended with the energy ray-curable monomer and / or oligomer (B), the energy ray-curable monomer and / or oligomer (B) in the energy ray-curable adhesive is used. The content of () is preferably 0.1 to 180 parts by mass, and particularly preferably 60 to 150 parts by mass with respect to 100 parts by mass of the energy ray-curable polymer (A).

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

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

  The photopolymerization initiator (C) is an energy ray-curable polymer (A) (when the energy ray-curable monomer and / or oligomer (B) is blended, the energy ray-curable polymer (A) and energy are used. The total amount of the linear curable monomer and / or oligomer (B) is 100 parts by mass) 0.1 to 10 parts by mass, particularly 0.5 to 6 parts by mass, relative to 100 parts by mass. Is preferred.

  In the energy ray-curable pressure-sensitive adhesive, other components may be appropriately blended in addition to the above components. Examples of the other component include a non-energy ray curable polymer component or oligomer component (D), a cross-linking agent (E), and a polymerizable branched polymer (F).

  Examples of the non-energy ray-curable polymer component or oligomer component (D) include polyacrylic acid ester, polyester, polyurethane, polycarbonate, polyolefin, and highly branched polymer, and the weight average molecular weight (Mw) thereof is 3,000 to 2,500,000. Polymers or oligomers of are preferred. By adding the component (D) to an energy ray-curable pressure-sensitive adhesive, tackiness and peelability before curing, strength after curing, easy peelability from an adherend, adhesiveness with other layers, storage Stability etc. can be improved. The blending amount of the component (D) is not particularly limited and is appropriately determined within the range of 0.01 to 50 parts by mass with respect to 100 parts by mass of the energy ray-curable polymer (A).

  As the cross-linking agent (E), a polyfunctional compound having reactivity with a functional group of the energy ray-curable polymer (A) or the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, Examples thereof include reactive phenol resins. By blending the crosslinking agent (E) with the energy ray-curable pressure-sensitive adhesive, the above-mentioned shearing force can be adjusted.

  The blending amount of the crosslinking agent (E) is preferably 0.01 to 8 parts by mass, and particularly 0.04 to 5 parts by mass, relative to 100 parts by mass of the energy ray-curable polymer (A). Is preferable, and more preferably 0.05 to 3.5 parts by mass.

  The polymerizable branched polymer (F) means a polymer having an energy ray-polymerizable group and a branched structure. The energy ray-curable pressure-sensitive adhesive contains a polymerizable branched polymer, whereby it is possible to suppress the migration of the organic substance from the pressure-sensitive adhesive layer to the semiconductor wafer or the semiconductor chip laminated on the pressure-sensitive adhesive sheet for stealth dicing, and stealth. In the step of individually picking up the semiconductor chips from the pressure-sensitive adhesive sheet for dicing, it is possible to reduce the mechanical load on the semiconductor chips. Although it is not clear how the polymerizable branched polymer (F) contributes to such effects, the polymerizable branched polymer (F) does not form an interface with the semiconductor wafer or the semiconductor chip in the adhesive layer. It is considered that the polymerizable branched polymer (F) tends to exist in the vicinity, and the polymerizable branched polymer (F) is irradiated with energy rays, whereby the energy ray-curable polymer (A) and the energy ray-curable monomer and / or Polymerization with the oligomer (B) may have an influence.

  The specific structure such as the molecular weight of the polymerizable branched polymer (F), the degree of the branched structure, and the number of energy ray-polymerizable groups in one molecule is not particularly limited. As an example of the method for obtaining such a polymerizable branched polymer (F), first, a monomer having two or more radical polymerizable double bonds in the molecule, an active hydrogen group and one radical polymerizable double bond are used. A polymer having a branched structure is obtained by polymerizing a monomer having a double bond in the molecule and a monomer having one radical-polymerizable double bond in the molecule. Next, the obtained polymer is reacted with a compound having a functional group capable of reacting with an active hydrogen group of the polymer to form a bond and at least one radical-polymerizable double bond in the molecule. Thus, the polymerizable branched polymer (F) can be obtained. As a commercially available product of the polymerizable branched polymer (F), for example, "OD-007" manufactured by Nissan Chemical Industries, Ltd. can be used.

  The weight average molecular weight (Mw) of the polymerizable branched polymer (F) is to appropriately suppress the interaction with the energy ray-curable polymer (A) and the energy ray-curable monomer and / or oligomer (B). From the viewpoint of facilitating the above, it is preferably 1000 or more, and particularly preferably 3000 or more. The weight average molecular weight (Mw) is preferably 100,000 or less, and particularly preferably 30,000 or less.

  Although the content of the polymerizable branched polymer (F) in the pressure-sensitive adhesive layer is not particularly limited, it is usually an energy ray curing from the viewpoint of satisfactorily obtaining the above-mentioned effects by containing the polymerizable branched polymer (F). It is preferably 0.01 part by mass or more, and more preferably 0.1 part by mass or more, relative to 100 parts by mass of the type polymer (A). Since the polymerizable branched polymer (F) has a branched structure, the above-mentioned effects can be satisfactorily obtained even if the content in the pressure-sensitive adhesive layer is relatively small.

  Depending on the type of the polymerizable branched polymer (F), the polymerizable branched polymer (F) may remain as particles on the contact surface of the semiconductor wafer or semiconductor chip with the adhesive layer. Since the particles may reduce the reliability of the product including the semiconductor chip, it is preferable that the number of remaining particles is small. Specifically, the number of particles having a particle diameter of 0.20 μm or more remaining on a silicon wafer as a semiconductor wafer is preferably less than 100, particularly preferably 50 or less. From the viewpoint of facilitating the fulfillment of such requirements regarding particles, the content of the polymerizable branched polymer (F) is 3.0 parts by mass with respect to 100 parts by mass of the energy ray-curable polymer (A). It is preferably less than 2.5 parts by mass, particularly preferably 2.5 parts by mass or less, and further preferably 2.0 parts by mass or less.

  Next, a case where the energy ray-curable pressure-sensitive adhesive mainly contains a mixture of a non-energy ray-curable polymer component and a monomer and / or oligomer having at least one energy ray-curable group will be described below. .

  As the non-energy ray curable polymer component, for example, the same component as the above-mentioned acrylic copolymer (a1) can be used.

  As the monomer and / or oligomer having at least one or more energy ray-curable groups, the same as the above-mentioned component (B) can be selected. The compounding ratio of the non-energy ray curable polymer component and the monomer and / or oligomer having at least one or more energy ray curable groups is at least one or more with respect to 100 parts by mass of the non-energy ray curable polymer component. The amount of the monomer and / or oligomer having an energy ray-curable group is preferably 1 to 200 parts by mass, and particularly preferably 60 to 160 parts by mass.

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

  The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as it can properly function in each step in which the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment is used. Specifically, it is preferably 1 to 50 μm, particularly preferably 3 to 40 μm, and further preferably 5 to 30 μm.

  The adhesive layer in the adhesive sheet for stealth dicing according to the present embodiment has a storage elastic modulus at 23 ° C. of preferably 1 to 5000 kPa, particularly preferably 3 to 3000 kPa, and further preferably 5 to 2500 kPa. It is preferable. When the storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. is in the above range, the pressure-sensitive adhesive sheet for stealth dicing becomes easy to expand, the chip interval is easily widened, and the chips can be washed more favorably. It will be possible. The method for measuring the storage elastic modulus is as shown in the test example described later.

2. Base Material The base material in the adhesive sheet for stealth dicing according to the present embodiment preferably has a storage elastic modulus at 23 ° C. of 10 MPa or more and 600 MPa or less. When the shearing force of the pressure-sensitive adhesive layer is in the above-mentioned range, and the storage elastic modulus of the substrate is in the above-mentioned range, due to their synergistic effect, the chips of the chip stuck to the pressure-sensitive adhesive sheet for stealth dicing The interval can be more sufficiently widened, and the chips can be effectively washed. The method for measuring the storage elastic modulus is as shown in the test example described later.

  Further, when the storage elastic modulus is 10 MPa or more, the base material exhibits a predetermined rigidity, so that the pressure-sensitive adhesive layer formed on the release sheet or the like can be laminated on the base material by transfer, and for stealth dicing efficiently. An adhesive sheet can be manufactured. Further, the handling property of the adhesive sheet for stealth dicing is improved. On the other hand, when the storage elastic modulus is 600 MPa or less, the pressure-sensitive adhesive sheet for stealth dicing expands well by expansion. Further, the semiconductor wafer can be favorably supported by the stealth dicing pressure-sensitive adhesive sheet attached to the ring frame.

  From the above viewpoint, the lower limit value of the storage elastic modulus is more preferably 50 MPa or more, and particularly preferably 100 MPa or more. Further, the upper limit value of the storage elastic modulus is more preferably 580 MPa or less, and particularly preferably 550 MPa or less.

  When performing a modified layer forming step of irradiating laser light through the adhesive sheet for stealth dicing to the semiconductor wafer attached to the adhesive sheet for stealth dicing, the base in the adhesive sheet for stealth dicing according to the present embodiment. The material preferably exhibits excellent light transmittance with respect to light having the wavelength of the laser light.

  Moreover, when using an energy ray for hardening an adhesive layer, it is preferable that a base material has a light transmittance with respect to the said energy ray. The energy rays will be described later.

  The base material in the adhesive sheet for stealth dicing according to the present embodiment preferably contains a film (resin film) containing a resin-based material as a main material, and particularly preferably composed of only the resin film. Specific examples of the resin film include ethylene-vinyl acetate copolymer film; ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylate methyl copolymer film, and other ethylene- (meth) acrylic films. Ethylene copolymer films such as acid ester copolymer films; polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, ethylene-norbornene copolymer films, norbornene resin films and other polyolefin films; polychlorination Polyvinyl chloride film such as vinyl film and vinyl chloride copolymer film; polyester film such as polyethylene terephthalate film, polybutylene terephthalate film and polyethylene naphthalate Beam; and the like fluororesin film; (meth) acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene films; polycarbonate films. Examples of the polyethylene film include a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene (HDPE) film and the like. In addition, modified films such as crosslinked films and ionomer films are also used. The base material may be a film made of one of these or a film made of a material obtained by combining two or more of these. Further, it may be a laminated film having a multilayer structure in which a plurality of layers made of one or more kinds of the above-mentioned materials are laminated. In this laminated film, the material forming each layer may be the same or different.

  Among the above-mentioned films, ethylene-methacrylic acid copolymer films, polyethylene films, polyolefin films such as polypropylene films, ionomer films of such polyolefins, polyvinyl chloride films, polyurethane films, or (meth) acrylic acid ester copolymers. It is preferable to use a polymer film, a film made of linear low-density polyethylene and polypropylene, or the like.

  In the substrate, the above film contains various additives such as a filler, a flame retardant, a plasticizer, an antistatic agent, a lubricant, an antioxidant, a colorant, an infrared absorber, an ultraviolet absorber, and an ion scavenger. It may be. Although the content of these additives is not particularly limited, it is preferably within a range in which the base material exhibits a desired function.

  When the base material and the pressure-sensitive adhesive layer are directly laminated in the stealth dicing pressure-sensitive adhesive sheet according to the present embodiment, the surface of the base material on the pressure-sensitive adhesive layer side is a primer in order to enhance adhesion with the pressure-sensitive adhesive layer. Surface treatment such as treatment, corona treatment, and plasma treatment may be performed.

  The thickness of the substrate is not limited as long as it can properly function in the process in which the pressure-sensitive adhesive sheet for stealth dicing is used. Usually, the thickness is preferably 20 to 450 μm, particularly preferably 25 to 250 μm, and further preferably 50 to 150 μm.

3. Release Sheet On the surface opposite to the base material side of the adhesive layer in the adhesive sheet for stealth dicing according to the present embodiment, until the adhesive sheet for stealth dicing is used, in order to protect the adhesive layer, A release sheet may be laminated.

  The release sheet is not particularly limited, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, Polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film A fluororesin film or the like can be used. Moreover, you may use these crosslinked films. Further, it may be a laminated film in which a plurality of these films are laminated.

  It is preferable that the release surface (the surface having releasability; particularly the surface in contact with the pressure-sensitive adhesive layer) of the release sheet is subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

  The thickness of the release sheet is not particularly limited and is usually about 20 μm to 100 μm.

4. Adhesive Force In the adhesive sheet for stealth dicing according to the present embodiment, the adhesive force to the silicon mirror wafer at 23 ° C. is preferably 1 N / 25 mm or more, and particularly preferably 2 N / 25 mm or more. Further, the adhesive force is preferably 30 N / 25 mm or less, and particularly preferably 29.5 N / 25 mm or less. When the adhesive strength at 23 ° C. is within the above range, when the adhesive sheet is expanded in the expanding step, it becomes easy to maintain the semiconductor wafer and the obtained semiconductor chip at a predetermined position, and the separation in the modified layer portion of the semiconductor wafer becomes easier. Can be satisfactorily performed. When the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive force means the pressure-sensitive adhesive force before irradiation with energy rays. In addition, the adhesive force means that measured by the method described later.

  In the pressure-sensitive adhesive sheet for stealth dicing according to this embodiment, when the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive force to the silicon mirror wafer after the energy ray irradiation at 23 ° C. is 10 mN / 25 mm or more. It is preferable that it is 20 mN / 25 mm or more. Further, the adhesive force is preferably 1000 mN / 25 mm or less, and particularly preferably 900 mN / 25 mm or less. After the individualization of the semiconductor wafer is completed, the adhesive sheet for stealth dicing can be irradiated with energy rays to reduce the adhesive force to the above range, so that the obtained semiconductor chip can be easily picked up. Becomes The adhesive force is measured by the method described below.

The adhesive force at 23 ° C. and the adhesive force after irradiation with energy rays at 23 ° C. described above can be measured by the following methods. First, a semiconductor processing sheet is cut into a width of 25 mm, and the adhesive layer side surface thereof is attached to a silicon mirror wafer. This sticking can be performed using a laminator (manufactured by Lintec Co., Ltd., product name "RAD-3510F / 12") under the conditions of a sticking speed of 10 mm / s, a wafer protrusion amount of 20 μm and a roller pressure of 0.1 MPa. Then, the obtained laminated body of the semiconductor processing sheet and the silicon mirror wafer is left for 20 minutes in an atmosphere of 23 ° C. and 50% RH. Here, when measuring the adhesive force after irradiation of energy rays at 23 ° C., after leaving it for 20 minutes, an ultraviolet irradiation device (manufactured by Lintec Co., product name “RAD-2000m / 12”) is applied to the laminate. ) Is used to perform ultraviolet (UV) irradiation (illuminance: 230 mW / cm ² , light amount: 190 mJ / cm ² ) from the base material side of the sheet in a nitrogen atmosphere. Following standing for 20 minutes or UV irradiation, the sheet was peeled at a peeling angle of 180 ° and a peeling speed of 300 mm / min using a universal tensile tester (manufactured by AMD, product name “RTG-1225”) according to JIS Z0237. Is peeled from the silicon mirror wafer, and the measured value is defined as the adhesive force (mN / 25 mm).

5. Method for Manufacturing Stealth Dicing Pressure-Sensitive Adhesive Sheet The method for manufacturing the stealth dicing pressure-sensitive adhesive sheet according to this embodiment is not particularly limited, and a conventional method can be used. As a first example of the manufacturing method, first, a pressure-sensitive adhesive composition containing the material of the pressure-sensitive adhesive layer and, if desired, a coating composition further containing a solvent or a dispersion medium are prepared. Next, the coating composition is applied to the release surface of the release sheet with a die coater, a curtain coater, a spray coater, a slit coater, a knife coater or the like to form a coating film. Further, the pressure-sensitive adhesive layer is formed by drying the coating film. Then, the pressure-sensitive adhesive layer on the release sheet and the base material are bonded together to obtain a pressure-sensitive adhesive sheet for stealth dicing. The property of the coating composition is not particularly limited as long as it can be applied. The component for forming the pressure-sensitive adhesive layer may be contained as a solute or a dispersoid in the coating composition.

  When the coating composition contains a cross-linking agent (E), the above drying conditions (temperature, time, etc.) may be changed in order to form a cross-linked structure with a desired existing density, or a heat treatment may be performed. It may be provided separately. In order to allow the crosslinking reaction to proceed sufficiently, the pressure-sensitive adhesive sheet for stealth dicing is usually prepared by laminating the pressure-sensitive adhesive layer on the substrate by the above method or the like, and then subjected to an environment of, for example, 23 ° C. and a relative humidity of 50%. Curing is done by leaving it for several days.

  As a second example of the method for producing a pressure-sensitive adhesive sheet for stealth dicing according to this embodiment, first, the coating composition is applied to one surface of a base material to form a coating film. Next, the coating film is dried to form a laminate including the base material and the pressure-sensitive adhesive layer. Further, the exposed surface of the pressure-sensitive adhesive layer in this laminate and the release surface of the release sheet are bonded together. Thereby, a pressure-sensitive adhesive sheet for stealth dicing in which a release sheet is laminated on the pressure-sensitive adhesive layer is obtained.

[Method of manufacturing semiconductor device]
A method for manufacturing a semiconductor device according to an embodiment of the present invention includes a bonding step of bonding a pressure-sensitive adhesive layer of the above-mentioned stealth dicing pressure-sensitive adhesive sheet (stealth dicing pressure-sensitive adhesive sheet according to this embodiment) and a semiconductor wafer. , Reforming layer forming step of forming the reforming layer inside the semiconductor wafer, and expanding the adhesive sheet for stealth dicing in a room temperature environment, and cutting the semiconductor wafer with the reforming layer formed inside into individual chips An expanding step of separating and a washing step of washing the chips laminated on the stealth dicing pressure-sensitive adhesive sheet in a state where the stealth dicing pressure-sensitive adhesive sheet is expanded are provided.

  In the above manufacturing method, the bonding step may be performed before the modified layer forming step, or conversely, the modified layer forming step may be performed before the bonding step. In the modified layer forming step in the former case, the semiconductor wafer attached to the adhesive sheet for stealth dicing according to the present embodiment is irradiated with laser light. In the modified layer forming step in the latter case, for example, a semiconductor wafer attached to another adhesive sheet (for example, a back grinding sheet) is irradiated with laser light.

  According to the method of manufacturing a semiconductor device according to the present embodiment, since the stealth dicing pressure-sensitive adhesive sheet described above is used at least in the cleaning step, by expanding the stealth dicing pressure-sensitive adhesive sheet, the intervals between the chips are sufficiently widened. be able to. Therefore, the cleaning liquid easily enters between the chips, and good chips can be cleaned.

  In addition, the method for manufacturing a semiconductor device according to the present embodiment, an adhesive film (DAF, NCF, etc.) is formed on the surface of the semiconductor wafer bonded to the adhesive sheet for stealth dicing on the side opposite to the adhesive sheet side for stealth dicing. May further include a laminating step of laminating. According to the method for manufacturing a semiconductor device of this embodiment, the adhesive film can be properly divided by the expanding step.

  Hereinafter, preferred specific examples of the method for manufacturing the semiconductor device according to the embodiment of the present invention will be described.

(1) Bonding Step First, the bonding step of bonding the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing and the semiconductor wafer according to the present embodiment is performed. Usually, the surface of the adhesive sheet for stealth dicing on the adhesive layer side is mounted on one surface of the semiconductor wafer, but the invention is not limited to this. In this bonding step, the ring frame is usually bonded to the area on the outer peripheral side of the area where the semiconductor wafer is bonded, on the surface of the adhesive sheet for stealth dicing on the adhesive layer side. In this case, a region where the adhesive layer is exposed exists between the ring frame and the semiconductor wafer as a peripheral region in a plan view.

(2) Laminating Step Next, a laminating step of laminating an adhesive film on the surface of the semiconductor wafer attached to the adhesive sheet for stealth dicing on the side opposite to the adhesive sheet for stealth dicing may be performed. This lamination is usually performed by heat lamination (thermal lamination). When the semiconductor wafer has electrodes on the surface, the electrodes are usually present on the surface of the semiconductor wafer opposite to the side of the adhesive sheet for stealth dicing, so that the adhesive film is laminated on the electrode side of the semiconductor wafer.

  The adhesive film may be DAF, NCF, or the like, and usually has a heat-sensitive adhesive property. The material is not particularly limited, and a specific example is a film-shaped member formed from an adhesive composition containing a heat-resistant resin material such as a polyimide resin, an epoxy resin, and a phenol resin, and a curing accelerator.

(3) Modified layer forming step Preferably, a modified layer forming step of forming a modified layer inside the semiconductor wafer is performed after the bonding step or the laminating step, but the modified layer is formed before those steps. You may perform a formation process. The modified layer forming step is usually performed by irradiating a laser beam in the infrared region so that the laser beam is focused on a focus set inside the semiconductor wafer (stealth dicing process). Irradiation with laser light may be performed from either side of the semiconductor wafer. When the modified layer forming step is performed after the laminating step, it is preferable to irradiate laser light through the adhesive sheet for stealth dicing. When the modified layer forming step is performed between the laminating step and the laminating step, or when the laminating step is not performed, the laser beam is directly applied to the semiconductor wafer without the adhesive sheet for stealth dicing. Irradiation is preferred.

(4) Expanding Step After the modified layer forming step, the expanding step of cutting and separating the semiconductor wafer is performed by expanding the adhesive sheet for stealth dicing in a room temperature environment. As a result, the semiconductor chip obtained by dividing the semiconductor wafer is stuck onto the adhesive layer of the adhesive sheet for stealth dicing. Further, when the adhesive film is laminated on the semiconductor wafer, the adhesive film is also divided at the same time as the division of the semiconductor wafer by the expanding step, and the chip with the adhesive layer is obtained.

  The specific conditions in the expanding step are not limited. For example, the temperature at which the pressure-sensitive adhesive sheet for stealth dicing is expanded can be a temperature for general expansion, and as described above, it is usually preferably 5 ° C. or higher, and particularly preferably 10 ° C. or higher. It is more preferable that the temperature is 15 ° C. or higher. Further, the temperature is usually preferably 45 ° C. or lower, particularly preferably 40 ° C. or lower, and further preferably 35 ° C. or lower.

(5) Washing Step After the expanding step, a washing step is performed in which the chips laminated on the stealth dicing pressure-sensitive adhesive sheet are washed while the stealth dicing pressure-sensitive adhesive sheet is expanded. The expanding in the washing step can be performed under general conditions, for example, the expanding performed in the expanding step may be maintained as it is also in the washing step, or after the expanding step is opened after the expanding step, the washing step is performed. For this purpose, the adhesive sheet for stealth dicing may be expanded again. Also, the washing can be performed under general conditions, and for example, the chips together with the stealth dicing pressure-sensitive adhesive sheet may be dipped in a washing liquid. As described above, by performing the washing process using the adhesive sheet for stealth dicing according to the present embodiment, it is possible to perform washing in a state where the obtained chip interval is sufficiently widened, and thus, the chips are attached. The crushed pieces can be removed well. The cleaning process may be performed after the shrinking process described below.

(6) Shrinking step When the expansion step causes slack in the peripheral area (area between the ring frame and the chip group in plan view) of the adhesive sheet for stealth dicing, the shrinking step heats the peripheral area. Is preferably performed. By heating the peripheral area of the adhesive sheet for stealth dicing, the base material located in this peripheral area shrinks, and it becomes possible to reduce the amount of slack in the adhesive sheet for stealth dicing that occurs in the expanding step. The heating method in the shrink process is not limited. Hot air may be blown, infrared rays may be irradiated, or microwaves may be irradiated.

(7) Pick-up process Adhesion for stealth dicing after the shrinking process after the cleaning process, after the shrinking process, after the shrinking process or after the cleaning process when the shrinking process is not performed A pickup step of individually picking up the chips attached to the sheet from the adhesive sheet for stealth dicing and obtaining the chips as a semiconductor device is performed.

  Here, in the case where the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing is made of an energy ray-curable pressure-sensitive adhesive, energy rays are irradiated to the pressure-sensitive adhesive layer at any stage after the bonding step and before the pickup step. It is preferable that the adhesive layer is cured to reduce the adhesive strength. As a result, the chip can be picked up more easily.

  Examples of energy rays include ionizing radiation, that is, X-rays, ultraviolet rays, and electron beams. Among these, ultraviolet rays, which are relatively easy to introduce irradiation equipment, are preferable.

When ultraviolet rays are used as the ionizing radiation, near ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm may be used for easy handling. The amount of ultraviolet light may be appropriately selected according to the type of energy ray-curable pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer, and is usually about 50 to 500 mJ / cm ² , and 100 to 450 mJ. / Cm ² is preferable, and 150 to 400 mJ / cm ² is more preferable. The ultraviolet illumination is usually 50 to 500 mW / cm ² or so, preferably from ^{100~450mW / cm 2, 150~400mW / cm} 2 is more preferable. The ultraviolet source is not particularly limited, and for example, a high pressure mercury lamp, a metal halide lamp, a light emitting diode (LED), etc. are used.

  When an electron beam is used as the ionizing radiation, its accelerating voltage may be appropriately selected depending on the type of energy ray-polymerizable group or energy ray-polymerizable compound contained in the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer. It is sufficient that the acceleration voltage is usually about 10 to 1000 kV. The irradiation dose may be appropriately selected according to the type of energy ray-curable pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer, and is usually selected in the range of 10 to 1000 krad. The electron beam source is not particularly limited, and for example, various electron beam accelerators such as Cockloft-Walton type, Van de Graft type, resonance transformer type, insulating core transformer type, linear type, dynamitron type, high frequency type, etc. are used. be able to.

  By carrying out the above manufacturing method, a semiconductor device can be manufactured using the adhesive sheet for stealth dicing according to this embodiment.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents within the technical scope of the present invention.

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

[Example 1]
(1) Preparation of adhesive composition Acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 80/5/15 (mass ratio), and its 2-hydroxyethyl acrylate To 80 mol% of methacryloyloxyethyl isocyanate (MOI) to obtain an energy ray-curable polymer. The weight average molecular weight (Mw) of this energy ray-curable polymer was 400,000.

  100 parts by mass of the obtained energy ray-curable polymer (solid content conversion value; similar notation below) and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (manufactured by BASF, product name "Irgacure 184") 3 Part by mass and 0.49 parts by mass of a tolylene diisocyanate cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") as a cross-linking agent were mixed in a solvent to obtain a pressure-sensitive adhesive composition.

(2) Production of pressure-sensitive adhesive sheet for stealth dicing The above-mentioned pressure-sensitive adhesive composition was applied onto the release surface of a release sheet (manufactured by Lintec Co., Ltd., product name "SP-PET3811"). Then, it was dried by heating, and the coating film of the pressure-sensitive adhesive composition was used as a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer had a thickness of 10 μm. Then, the pressure-sensitive adhesive layer on the obtained release sheet, and an ethylene-methacrylic acid copolymer (EMAA) film having one surface corona-treated as a substrate (thickness: 80 μm, surface tension of corona-treated surface: 54 mN The adhesive sheet for stealth dicing was obtained by laminating the corona treated surface of / m).

[Example 2]
Acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / vinyl acetate / 2-hydroxyethyl acrylate = 60/20/20 (mass ratio), and 80 mol% of the acrylic copolymer based on the 2-hydroxyethyl acrylate. An energy ray-curable polymer (Mw: 400,000) was obtained by reacting with methacryloyloxyethyl isocyanate (MOI).

  100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent. 0.31 parts by mass of a system crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain an adhesive composition. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Example 3]
100 parts by mass of an acrylic copolymer (Mw: 600,000) obtained by reacting 2-ethylhexyl acrylate / methyl acrylate / acrylic acid = 50/40/10 (mass ratio) and an energy ray-curable group 120 parts by mass of a 5- to 6-functional urethane acrylate (manufactured by Dainichiseika Co., Ltd., product name "SEICA BEAM 14-29B") as a monomer and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (manufactured by BASF, product name " 3 parts by mass of Irgacure 184 ") and 0.286 parts by mass of 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name" Tetrad C ") as a cross-linking agent. And were mixed in a solvent to obtain an adhesive composition. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Example 4]
Linear low-density polyethylene resin (made by Ube Maruzen Polyethylene Co., Ltd., product name "Umerit 3540F") and polypropylene resin (made by Idemitsu Petrochemical Co., Ltd., product name "F-724NP") are extruded by Toyo Seiki Seisakusho. A film having a thickness of 80 μm was manufactured by extrusion molding. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 2, except that one surface of the film was corona-treated and used as a substrate.

[Example 5]
Acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 62/10/28 (mass ratio), and 80 mol% of methacryloyloxy based on the 2-hydroxyethyl acrylate. An energy ray-curable polymer (Mw: 400,000) was obtained by reacting with ethyl isocyanate (MOI).

  100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent. 1.61 parts by mass of a system crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name “Coronate L”) were mixed in a solvent to obtain an adhesive composition. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Comparative Example 1]
Acrylic copolymer obtained by reacting lauryl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio), and 80 mol% methacryloyloxy based on the 2-hydroxyethyl acrylate. An energy ray-curable polymer (Mw: 400,000) was obtained by reacting with ethyl isocyanate (MOI).

  100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent. A pressure-sensitive adhesive composition was obtained by mixing 1.07 parts by mass of a system crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") in a solvent. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Comparative Example 2]
Acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio), and 80 mol% of the acrylic copolymer based on the 2-hydroxyethyl acrylate. An energy ray-curable polymer (Mw: 400,000) was obtained by reacting with methacryloyloxyethyl isocyanate (MOI).

  100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent. A pressure-sensitive adhesive composition was obtained by mixing 1.07 parts by mass of a system crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") in a solvent. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Comparative Example 3]
80 moles based on the acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / isobornyl acrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and the 2-hydroxyethyl acrylate. % Of methacryloyloxyethyl isocyanate (MOI) to give an energy ray-curable polymer (Mw: 400,000).

  100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent. A pressure-sensitive adhesive composition was obtained by mixing 1.07 parts by mass of a system crosslinking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") in a solvent. A pressure-sensitive adhesive sheet for stealth dicing was produced in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive composition was used.

[Test Example 1] (measurement of shearing force)
On the surface of the adhesive sheet for stealth dicing obtained in Examples and Comparative Examples, on the side opposite to the adhesive layer, an instant adhesive (manufactured by Toagosei Co., Ltd., product name "Aron Alpha") was used for backing. A polyethylene terephthalate film (thickness: 100 μm) as a material was adhered to obtain a laminate.

The obtained laminate was cut into a length of 50 mm and a width of 30 mm in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and then the release sheet was released from the pressure-sensitive adhesive layer to obtain a sample. This sample was attached to the mirror surface of a silicon mirror wafer (thickness: 350 μm) under an environment of a temperature of 23 ° C. and a relative humidity of 50% via an adhesive layer. At this time, a 2 kg roller was reciprocated once on the sample to apply a load, and the sample was attached so that a 3 mm portion in the length direction of the sample was in close contact with the silicon mirror wafer. Next, on the silicon mirror wafer, only the sample was cut with a cutter so that the width of the sample was 20 mm, and unnecessary cut pieces of the sample were peeled from the silicon mirror wafer. Thereby, as shown in FIGS. 1 and 2, a test object was obtained in which the sample and the silicon mirror wafer were attached to each other in a region of 20 mm × 3 mm (60 mm ² ). 1 and 2, reference numeral 1 is an adhesive sheet (sample) for stealth dicing with a backing material, reference numeral 2 is a silicon mirror wafer, reference numeral 11 is a base material, reference numeral 12 is an adhesive layer, and reference numeral 13 is a backing material. Indicates.

  Twenty minutes after application, a tensile test was performed using an autograph (manufactured by Imada Seisakusho Co., Ltd., product name "SDT-203NB-50R3") under a condition of a tensile speed of 1 mm / min in an environment of 23 ° C. , Shearing force (N / (3 mm × 20 mm)) was measured. The results are shown in Table 1.

[Test Example 2] (Measurement of Storage Elastic Modulus of Base Material)
With respect to the base material used in the examples and comparative examples, the storage elastic modulus (MPa) of the base material at 23 ° C. was measured with the following apparatus and conditions. The results are shown in Table 1.
Measuring device: manufactured by TA Instruments, dynamic elastic modulus measuring device "DMA Q800"
Test start temperature: 0 ℃
Test end temperature: 200 ° C
Temperature rising rate: 3 ° C / min Frequency: 11Hz
Amplitude: 20 μm

[Test Example 3] (Measurement of storage elastic modulus of adhesive layer)
The pressure-sensitive adhesive composition used in Examples and Comparative Examples was applied to the release surface of the release sheet to form a pressure-sensitive adhesive layer, and the release surface of the release sheet separately prepared was pressure-bonded to the exposed pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet composed of a release sheet / a pressure-sensitive adhesive layer / a release sheet was prepared. The release sheet was peeled off from the pressure-sensitive adhesive sheet, and a plurality of pressure-sensitive adhesive layers were laminated to have a thickness of 200 μm. A 30 mm × 4 mm rectangle (thickness: 200 μm) was punched out from the obtained pressure-sensitive adhesive layer laminate, and this was used as a measurement sample. With respect to this measurement sample, the storage elastic modulus (kPa) of the pressure-sensitive adhesive layer at 23 ° C. was measured using the following apparatus and conditions. The results are shown in Table 1.
Measuring device: manufactured by TA Instruments, dynamic elastic modulus measuring device "DMA Q800"
Distance between measurements: 20 mm
Test start temperature: -30 ° C
Test end temperature: 120 ° C
Temperature rising rate: 3 ° C / min Frequency: 11Hz
Amplitude: 20 μm

[Test Example 4] (Evaluation of detergency)
A 6-inch ring frame and a mirror surface of a 6-inch silicon mirror wafer (thickness: 100 μm) were attached to the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets for stealth dicing obtained in Examples and Comparative Examples. Then, using a stealth dicing device (manufactured by Disco, product name "DFL7360"), under the following conditions, a laser is irradiated from the surface of the 6-inch silicon mirror wafer opposite to the adhesive sheet for stealth dicing, A modified layer was formed in a 6-inch silicon mirror wafer. The laser irradiation at this time was performed so that the size of the obtained chip was 8 mm square.
<Irradiation conditions>
Irradiation height: 68 μm from tape side
Frequency: 90Hz
Output: 0.3W
Processing speed: 360 mm / sec

Then, using an expanding device (manufactured by JCM, product name “ME-300B”), the work was expanded at a drawing speed of 100 mm / sec and a drawing amount of 10 mm under an environment of 23 ° C. Immediately after that, the chip interval (μm) was measured with a digital microscope (manufactured by KEYENCE, product name “VHX-1000”), and an average value of arbitrary 5 points was calculated. This average value was used as the chip interval (μm) immediately after expansion. In addition, the detergency was evaluated based on the following criteria from the value of the chip interval immediately after the expansion. The respective results are shown in Table 1.
◯: Chip spacing is 150 μm or more ×: Chip spacing is less than 150 μm

  As can be seen from Table 1, the adhesive sheet for stealth dicing obtained in the example had a sufficiently wide chip interval due to expansion, and showed excellent cleaning properties.

  The pressure-sensitive adhesive sheet for stealth dicing according to the present invention is suitably used in a method for manufacturing a semiconductor device that performs an expanding step and a cleaning step.

1 ... Adhesive sheet for stealth dicing with backing material (sample)
11 ... Base material 12 ... Adhesive layer 13 ... Backing material 2 ... Silicon mirror wafer

Claims (5)

At least a stealth dicing pressure-sensitive adhesive sheet used for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment,
A base material and an adhesive layer laminated on one surface side of the base material,
When the adhesive sheet for stealth dicing is attached to a silicon wafer via the adhesive layer, the shearing force at 23 ° C. at the interface between the adhesive layer and the silicon wafer is 5 N / (3 mm × 20 mm) or more. , 70 N / (3 mm × 20 mm) or less, a pressure-sensitive adhesive sheet for stealth dicing.   The pressure-sensitive adhesive sheet for stealth dicing according to claim 1, wherein the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive.   The adhesive sheet for stealth dicing according to claim 1 or 2, wherein the storage elastic modulus of the base material at 23 ° C is 10 MPa or more and 600 MPa or less. A bonding step of bonding the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing according to any one of claims 1 to 3 and a semiconductor wafer,
A modified layer forming step of forming a modified layer inside the semiconductor wafer;
Expanding the pressure-sensitive adhesive sheet for stealth dicing under a room temperature environment, an expanding step of cutting and separating the semiconductor wafer in which the modified layer is formed into individual chips,
A method of manufacturing a semiconductor device, comprising: a cleaning step of cleaning the chip laminated on the stealth dicing pressure-sensitive adhesive sheet in the expanded state of the stealth dicing pressure-sensitive adhesive sheet.   The laminating step of laminating an adhesive film on the surface of the semiconductor wafer attached to the adhesive sheet for stealth dicing, which is opposite to the adhesive sheet side for stealth dicing, is further provided. A method for manufacturing a semiconductor device as described above.

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