KR102560374B1 - Method for manufacturing adhesive sheet for stealth dicing and semiconductor device - Google Patents

Abstract

At least, a pressure-sensitive adhesive sheet (1) for stealth dicing used for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment, comprising a substrate (11) and one side of the substrate (11) 23 of the interface between the pressure-sensitive adhesive layer 12 and the silicon wafer when the pressure-sensitive adhesive layer 12 is laminated and the pressure-sensitive adhesive sheet 1 for stealth dicing is attached to the silicon wafer through the pressure-sensitive adhesive layer 12 An adhesive sheet (1) for stealth dicing having a shear force at ° C. of 70 N/(3 mm×20 mm) or more and 250 N/(3 mm×20 mm) or less. This pressure-sensitive adhesive sheet 1 for stealth dicing can favorably separate a semiconductor wafer into chips even when expanding at room temperature.

Description

Method for manufacturing adhesive sheet for stealth dicing and semiconductor device

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

Conventionally, when manufacturing a chip-shaped semiconductor device from a semiconductor wafer, a blade dicing process in which chips are obtained by cutting the semiconductor wafer with a rotating blade while spraying a liquid for cleaning or the like to the semiconductor wafer has been generally performed. However, in recent years, a stealth dicing process capable of dividing into chips in a dry process has been adopted. In the stealth dicing process, as an example, a laser beam having a large aperture (NA) is irradiated to a semiconductor wafer attached to a dicing sheet, and the inside of the semiconductor wafer is minimized while minimizing damage received near the surface of the semiconductor wafer. A modified layer is preliminarily formed thereon. After that, by expanding the dicing sheet, a force is applied to the semiconductor wafer to cut and separate into individual chips.

[0003] In recent years, there has been a demand for stacking other chips on the chips manufactured as described above or bonding the chips on a film substrate. Then, in a face-up type mounting in which a circuit on a chip and a circuit on another chip or board are connected by wires, the electrode formation surface of the chip provided with protruding electrodes faces the circuit on another chip or board, and the electrodes In some fields, flip-chip mounting for direct connection and transition to Through Silicon Via (TSV) are being performed. In response to the demand for stacking and bonding of chips in flip chip mounting and the like, a method of fixing a chip having an electrode to another chip or a film substrate using an adhesive has been proposed.

And, in order to be easily applicable to these applications, in the course of the above manufacturing method, a semiconductor wafer having an electrode or a modified semiconductor wafer having an electrode having a dicing sheet attached to a surface opposite to the electrode formation surface, the electrode It has been proposed to laminate a film-shaped adhesive on the formation surface and to have an adhesive layer on the electrode formation surface of a chip having electrodes divided by an expand process. As such an adhesive layer, an adhesive film called a die attach film (DAF) or a nonconductive adhesive film (NCF) is used.

Patent Literature 1 discloses that DAF is attached to a wafer, stealth dicing is performed, and then the wafer is separated into chips by expanding and the DAF is divided.

Patent Document 1: Japanese Unexamined Patent Publication No. 2005-19962

Since the above-described DAF or NCF has a characteristic of becoming brittle in a low temperature region, in order to improve the splitting property of DAF or NCF, a cool expand process in which the expand is performed in a low temperature environment of about -20 ° C to 10 ° C is required. It is doing more and more.

However, in order to perform the cool expand step, the initial cost becomes higher compared to the case of performing the expand at room temperature because it is necessary to introduce facilities capable of realizing temperature control. For this reason, from a viewpoint of cost, the method of performing expansion at room temperature is preferable instead of a cool-expanding process.

The present invention has been made in view of the above factual situation, and an object of the present invention is to provide an adhesive sheet for stealth dicing and a method for manufacturing a semiconductor device that can satisfactorily separate a semiconductor wafer into chips even when expanding at room temperature. .

In order to achieve the above object, the first invention of the present invention is at least an adhesive sheet for stealth dicing used for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips under a room temperature environment, comprising: a base material; and the base material A pressure-sensitive adhesive layer laminated on one side of the pressure-sensitive adhesive layer, and when the pressure-sensitive adhesive sheet for stealth dicing is attached to a silicon wafer through the pressure-sensitive adhesive layer, the shear force at the interface between the pressure-sensitive adhesive layer and the silicon wafer at 23 ° C. is 70 An adhesive sheet for stealth dicing characterized in that N/(3 mm×20 mm) or more and 250 N/(3 mm×20 mm) or less is provided (Invention 1).

In the pressure-sensitive adhesive sheet for stealth dicing according to the above invention (invention 1), the shear force at 23 ° C. is within the above range, and when expanding at room temperature, the pressure-sensitive adhesive sheet for stealth dicing and on the pressure-sensitive adhesive sheet for stealth dicing It becomes difficult to generate a shift|offset|difference at the interface of the laminated semiconductor wafer. As a result, the force for pulling the semiconductor wafer in the periphery direction, generated by the expansion of the pressure-sensitive adhesive sheet for stealth dicing, tends to concentrate on the modified layer, and as a result, the semiconductor wafer can be divided favorably in the modified layer. . For this reason, even when expanding is performed at room temperature, occurrence of splitting failure or chip breakage is suppressed, and chips that are well separated can be obtained.

In the above invention (Invention 1), it is preferable that the length of the smallest side of the chip is 2 mm or more and 30 mm or less (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the semiconductor wafer has a thickness of 10 μm or more and 1000 μm or less (Invention 3).

In the above inventions (Inventions 1 to 3), it is preferable that the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive (Invention 4).

In the above inventions (Inventions 1 to 4), it is preferable that the storage elastic modulus of the substrate at 23°C is 10 MPa or more and 600 MPa or less (Invention 5).

The second present invention is a bonding step of bonding the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing (Inventions 1 to 5) and a semiconductor wafer, a modified layer forming step of forming a modified layer inside the semiconductor wafer, and room temperature Provided is a semiconductor device manufacturing method comprising an expand step of expanding the pressure-sensitive adhesive sheet for stealth dicing under an environment and cutting and separating the semiconductor wafer having a modified layer therein into individual chips (invention 6).

In the above invention (invention 6), a lamination step of laminating an adhesive film is further provided on the side opposite to the side of the pressure-sensitive adhesive sheet for stealth dicing in the semiconductor wafer bonded to the pressure-sensitive adhesive sheet for stealth dicing. Preferred (Invention 7).

ADVANTAGE OF THE INVENTION According to this invention, even when expanding at room temperature, the adhesive sheet for stealth dicing which can favorably separate a semiconductor wafer into chips and the manufacturing method of a semiconductor device are provided.

1 is a plan view illustrating a method for measuring shear force related to Test Example 1.
2 is a cross-sectional view illustrating a method for measuring shear force related to Test Example 1.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is 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, under a room temperature environment means, for example, under an environment of 5°C or higher, preferably under an environment of 10°C or higher, and more preferably under an environment of 15°C or higher. Further, under a room temperature environment means, for example, under an environment of 45°C or less, and particularly preferably under an environment of 40°C or less, and more preferably under an environment of 35°C or less. Since the above temperature range is easy to achieve even without intentionally performing temperature control, the cost of stealth dicing can be reduced. In addition, the concept of a "tape" shall also be included in the "sheet" in this specification.

The pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment includes a base material and a pressure-sensitive adhesive layer laminated on one side of the base material. It is preferable that the base material and the pressure-sensitive adhesive layer are directly laminated, but it is not limited thereto.

When the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment is attached to a silicon wafer via the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet for stealth dicing, the shear force at the interface between the pressure-sensitive adhesive layer and the silicon wafer at 23° C. is 70 N/( 3 mm x 20 mm) or more and 250 N/(3 mm x 20 mm) or less.

The pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment has the above shear force, and when the pressure-sensitive adhesive sheet for stealth dicing in which semiconductor wafers provided with a modified layer are laminated is expanded at room temperature, the pressure-sensitive adhesive sheet for stealth dicing and It becomes difficult to produce a shift|offset|difference at the interface of a semiconductor wafer. For this reason, the force which pulls the semiconductor wafer in the direction of its periphery, which is generated by the expansion of the pressure-sensitive adhesive sheet for stealth dicing, is less likely to be damaged. As a result, the force tends to concentrate on the modified layer, and the semiconductor wafer can be divided favorably in the modified layer. As a result, even when expanding is performed at room temperature, occurrence of splitting defects or chip breakage is suppressed, and chips that are well separated can be obtained.

In addition, when the shear force is less than 70 N/(3 mm×20 mm), especially when the chip size is small, during expansion, displacement at the interface between the adhesive sheet for stealth dicing and the semiconductor wafer tends to occur, and the semiconductor wafer cannot be cut and separated satisfactorily. On the other hand, if the shear force exceeds 250 N/(3 mm x 20 mm), the adhesive sheet for stealth dicing does not develop sufficient tack, and the obtained chips cannot be satisfactorily held on the adhesive sheet for stealth dicing.

From the above viewpoint, the lower limit of the shear force is preferably 80 N/(3 mm×20 mm) or more, and particularly preferably 90 N/(3 mm×20 mm) or more. Further, the upper limit of the shear force is preferably 200 N/(3 mm×20 mm) or less, particularly preferably 180 N/(3 mm×20 mm) or less. In addition, the method of measuring the shear force is as shown in the test examples described later.

When the adhesive sheet for stealth dicing according to the present embodiment is used and a semiconductor wafer having a modified layer formed therein is cut and separated into individual chips in a room temperature environment, the resulting chips have a minimum side length of 2 mm to 30 mm It is preferable that the length is 2.5 mm to 25 mm, and it is preferable that the length is 3 mm to 20 mm.

Further, when the adhesive sheet for stealth dicing according to the present embodiment is used and a semiconductor wafer having a modified layer formed therein is cut and separated into individual chips in a room temperature environment, the semiconductor wafer has a thickness of 10 μm to 1000 μm or less It is preferable, and it is especially preferable that the said thickness is 20 micrometers - 950 micrometers or less, and it is preferable that the said thickness is 30 micrometers - 900 micrometers or less.

As described above, according to the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment, during expansion at room temperature, displacement at the interface between the pressure-sensitive adhesive sheet for stealth dicing and the semiconductor wafer is suppressed, and the semiconductor wafer is cut satisfactorily. can be separated For this reason, the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment is suitable for manufacturing chips having the above-described chip size at a low cost.

1. Adhesive layer

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment is not particularly limited as long as it satisfies the above shear force. The pressure-sensitive adhesive layer may be composed of a non-energy ray-curable pressure-sensitive adhesive or may be composed of an energy ray-curable pressure-sensitive adhesive. As the non-energy ray curable adhesive, those having desired adhesive strength and re-peelability are preferable, and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, and the like. there is. Among these, an acrylic pressure-sensitive adhesive capable of effectively suppressing the dropping of semiconductor wafers, chips, etc. in a modified layer formation process, an expand process, or the like is preferable.

On the other hand, energy ray-curable pressure-sensitive adhesive is cured by energy ray irradiation and its adhesive strength decreases. Therefore, when it is desired to separate a chip obtained by dividing a semiconductor wafer and an adhesive sheet for stealth dicing, it can be easily separated by irradiating energy ray. can

The energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may have a polymer having energy ray curability as a main component, and a monomer having a non-energy ray curable polymer (a polymer having no energy ray curable property) and at least one energy ray curable group. And/or a mixture of oligomers as a main component may be used. Further, it may be a mixture of a polymer having energy radiation curability and a non-energy radiation curable polymer, or a mixture of a polymer having energy radiation curability and a monomer and/or oligomer having at least one energy radiation curable group, or a mixture of these three types. It is also good.

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

A polymer having energy radiation curability is a (meth)acrylic acid ester (co)polymer (A) in which a functional group having energy radiation curability (energy radiation curable group) is introduced into a side chain (hereinafter referred to as “energy radiation curable polymer (A)”). There are cases.) is preferable. This energy ray-curable polymer (A) is preferably 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. In addition, in this specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same goes for 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 structural unit of the acrylic copolymer (a1) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, or an epoxy group in the molecule.

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. are mentioned, These are used individually or in combination of 2 or more types.

Examples of the carboxyl 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 independently or may be used in combination of 2 or more types.

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 independently or may be used in combination of 2 or more types.

Examples of the (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1) include alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group, and, for example, monomers having an alicyclic structure in the molecule (containing an alicyclic structure). monomer) is preferably used.

Examples of the alkyl (meth)acrylate include, in particular, an alkyl (meth)acrylate having 1 to 18 carbon atoms in the alkyl group, such as 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 individually by 1 type, and may be used in combination of 2 or more types.

Examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, Dicyclopentenyloxyethyl (meth)acrylic acid and the like are preferably used. These may be used individually by 1 type, and may be used in combination of 2 or more types.

In the acrylic copolymer (a1), the structural unit derived from the functional group-containing monomer is preferably 1 to 35% by mass, particularly preferably 5 to 30% by mass, and more preferably 10 to 25% by mass. contain In addition, the acrylic copolymer (a1) contains preferably 50 to 99% by mass, particularly preferably 60 to 95% by mass, more preferably 70% by mass of structural units derived from (meth)acrylic acid ester monomers or derivatives thereof. It is contained at a rate of ~ 90% by mass.

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

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

The functional group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the kind of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group of the acrylic copolymer (a1) is a hydroxyl group, amino group or substituted amino group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group, and the acrylic copolymer (a1) has When the functional group is an epoxy group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxyl group or an aziridinyl group.

In addition, the compound containing an unsaturated group (a2) contains at least one, preferably 1 to 6, more preferably 1 to 4 energy ray polymerizable carbon-carbon double bonds per molecule. Specific examples of such an 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 compounds obtained by reaction of a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by reaction of a diisocyanate compound or a polyisocyanate compound, a polyol compound, and hydroxyethyl (meth)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 amount of the unsaturated group-containing compound (a2) is preferably 50 to 95 mol%, particularly preferably 60 to 93 mol%, more preferably 70 to 95 mol%, based on the number of moles of the functional group-containing monomer in the acrylic copolymer (a1). It is used in a ratio of ~ 90 mol%.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, and solvent depend on the combination of the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2). , time, the presence or absence of a catalyst, and the 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 introduced into the side chain in the acrylic copolymer (a1) to obtain the energy ray curable polymer (A). lose

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 1.5 million, and more preferably 200,000 to 1,000,000. In addition, the weight average molecular weight (Mw) in this specification is a standard polystyrene conversion value measured by gel permeation chromatography (GPC method).

Even when the energy ray-curable pressure-sensitive adhesive contains, as a main component, a polymer having energy ray-curable property called energy ray-curable polymer (A), the energy ray-curable pressure-sensitive adhesive may further contain an energy ray-curable monomer and/or oligomer (B). .

As the energy ray-curable monomer and/or oligomer (B), for example, an ester of a polyhydric alcohol and (meth)acrylic acid or the like 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) Acrylates, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di Polyfunctional acrylic acid esters such as (meth)acrylate, polyethylene glycol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, polyester oligo(meth)acrylate, polyurethane oligo(meth)acrylate A rate etc. are mentioned.

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

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

As the photopolymerization initiator (C), specifically, benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate , benzoin dimethyl ketal, 2,4-diethyl thioxanthone, 1-hydroxycyclohexylphenyl ketone, benzyldiphenylsulfide, tetramethylthiurammonosulfide, azobisisobutyronitrile, benzyl, dibenzyl, di Acetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl) phosphineoxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy- 2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2,2-dimethoxy-1,2-diphenylethan-1-one, etc. are mentioned. These may be used independently and may use 2 or more types together.

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

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

Examples of the non-energy ray-curable polymer component or oligomer component (D) include polyacrylic acid esters, polyesters, polyurethanes, polycarbonates, polyolefins, and highly branched polymers, and the weight average molecular weight (Mw) A polymer or oligomer of 3000 to 2.5 million is preferable. By blending the above component (D) into the energy ray-curable pressure-sensitive adhesive, the adhesiveness and releasability before curing, the strength after curing, the easy releasability from adherends, the adhesiveness with other layers, storage stability, etc. can be improved. there is. The blending amount of the component (D) is not particularly limited, and is appropriately determined in 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 crosslinking 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, reactive phenolic resins, and the like. can be heard The shear force described above can be adjusted by blending the crosslinking agent (E) into the energy ray-curable pressure-sensitive adhesive.

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

The polymerizable branched polymer (F) means a polymer having an energy ray polymerizable group and a branched structure. When the energy ray-curable pressure-sensitive adhesive contains a polymerizable branched polymer, transfer of organic substances from the pressure-sensitive adhesive layer to the semiconductor wafer or semiconductor chip stacked on the pressure-sensitive adhesive sheet for stealth dicing can be suppressed, and from the pressure-sensitive adhesive sheet for stealth dicing In the process of individually picking up the semiconductor chips, it is possible to reduce the mechanical load applied to the semiconductor chips. Although it is not clear how the polymerizable branched polymer (F) contributes to these effects, it is thought that the polymerizable branched polymer (F) tends to be present in the vicinity of the interface of the semiconductor wafer or semiconductor chip in the pressure-sensitive adhesive layer. However, there is a possibility that the polymerizable branched polymer (F) is polymerized with the energy ray curable polymer (A) or the energy ray curable monomer and/or oligomer (B) by energy ray irradiation.

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

The weight average molecular weight (Mw) of the polymerizable branched polymer (F) facilitates moderately suppressing the interaction between the energy ray-curable polymer (A) and the energy ray-curable monomer and/or oligomer (B), It is preferably 1000 or more, and particularly preferably 3000 or more. Further, the weight average molecular weight (Mw) is preferably 100,000 or less, particularly preferably 30,000 or less.

The content of the polymerizable branched polymer (F) in the pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of favorably obtaining the above-mentioned effects by containing the polymerizable branched polymer (F), energy ray curable polymer (A) 100 Regarding parts by mass, it is preferably 0.01 parts by mass or more, and preferably 0.1 parts by mass or more. Since the polymerizable branched polymer (F) has a branched structure, even if the content in the pressure-sensitive adhesive layer is relatively small, the above-mentioned effects can be satisfactorily obtained.

Depending on the type of the polymerizable branched polymer (F), the polymerizable branched polymer (F) may remain as particles on the contact surface with the pressure-sensitive adhesive layer in the semiconductor wafer or semiconductor chip. Since these particles may deteriorate the reliability of products including semiconductor chips, 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, and particularly preferably 50 or less. From the viewpoint of facilitating the satisfaction of such a request for particles, the content of the polymerizable branched polymer (F) is preferably less than 3.0 parts by mass with respect to 100 parts by mass of the energy ray curable polymer (A), particularly. It is preferable to set it as 2.5 mass parts or less, and it is more preferable to set it as 2.0 mass parts or less.

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

As the non-energy ray-curable polymer component, components similar to those of the above-described acrylic copolymer (a1) can be used, for example.

As the monomer and/or oligomer having at least one or more energy ray-curable groups, those similar to those of component (B) described above can be selected. The blending ratio of the non-energy ray-curable polymer component and the monomer and/or oligomer having at least one energy ray-curable group is the monomer and/or oligomer having at least one energy ray-curable group with respect to 100 parts by mass of the non-energy ray-curable polymer component. It is preferable that it is 1-200 mass parts of oligomers, and it is especially preferable that it is 60-160 mass parts.

Also in this case, the photopolymerization initiator (C) and the crosslinking agent (E) can be appropriately blended 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 more preferably 5 to 30 μm.

The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment preferably has a storage modulus at 23°C of 1 to 5000 kPa, particularly preferably 3 to 3000 kPa, and more preferably 5 to 2500 kPa. desirable. When the storage elastic modulus at 23°C of the pressure-sensitive adhesive layer is within the above range, the pressure-sensitive adhesive sheet for stealth dicing is easy to expand, and chips can be divided satisfactorily. In addition, the method of measuring the storage elastic modulus is as shown in the test examples described later.

2. Description

It is preferable that the storage elastic modulus at 23 degreeC of the base material of the adhesive sheet for stealth dicing concerning this embodiment is 10 MPa or more and 600 MPa or less. When the shear force of the pressure-sensitive adhesive layer is within the above range and the storage modulus of the base material is within the above range, the pressure-sensitive adhesive sheet for stealth dicing can be sufficiently stretched while suppressing displacement at the interface between the pressure-sensitive adhesive sheet for stealth dicing and the semiconductor wafer. As a result, the semiconductor wafer can be well divided into chips. In addition, the method of measuring the storage elastic modulus is as shown in the test examples described later.

In addition, when the storage modulus is 10 MPa or more, since the base material exhibits a predetermined rigidity, the pressure-sensitive adhesive layer formed on the release sheet or the like can be laminated on the base material by transfer, and the pressure-sensitive adhesive sheet for stealth dicing can be efficiently manufactured. . Moreover, the handling property of the adhesive sheet for stealth dicing also becomes favorable. On the other hand, if the storage elastic modulus is 600 MPa or less, the semiconductor wafer can be favorably supported by the adhesive sheet for stealth dicing attached to the ring frame.

From the above viewpoint, the lower limit of the storage modulus is more preferably 50 MPa or more, and particularly preferably 100 MPa or more. Moreover, as for the upper limit of the said storage elastic modulus, it is more preferable that it is 580 MPa or less, and it is especially preferable that it is 550 MPa or less.

In the case of performing a modified layer forming step of irradiating a laser beam through the adhesive sheet for stealth dicing to a semiconductor wafer bonded to the adhesive sheet for stealth dicing, the base material in the adhesive sheet for stealth dicing according to the present embodiment is It is desirable to exhibit excellent light transmittance with respect to light of the wavelength of laser light.

Further, when energy rays are used to cure the pressure-sensitive adhesive layer, the base material preferably has light transmittance to the energy rays. The energy line will be described later.

The base material of the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment preferably includes a film (resin film) mainly composed of a resin-based material, and is particularly preferably composed of only a resin film. Specific examples of the resin film include an ethylene-vinyl acetate copolymer film; Ethylene-based copolymer films, such as an ethylene-(meth)acrylic acid copolymer film, an ethylene-methyl (meth)acrylate copolymer film, and other ethylene-(meth)acrylic acid ester copolymer films; Polyolefin films, such as a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, an ethylene-norbornene copolymer film, and a norbornene resin film; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; Polyester films, such as a polyethylene terephthalate film, a polybutylene terephthalate film, and a polyethylene naphthalate; (meth)acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; A fluororesin film etc. are mentioned. As an example of a polyethylene film, a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene (HDPE) film, etc. are mentioned. In addition, these crosslinked films and modified films of 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. Alternatively, it may be a laminated film having a multilayer structure in which a plurality of layers made of one or more of the above materials are laminated. In this laminated film, the materials constituting each layer may be of the same type or of different types.

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

In the substrate, various additives such as fillers, flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion trapping agents may be contained in the above films. The content of these additives is not particularly limited, but is preferably within a range in which the base material exhibits desired functions.

In the case where the base material and the pressure-sensitive adhesive layer are directly laminated in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment, the surface of the base material on the pressure-sensitive adhesive layer side is subjected to priming, corona treatment, or plasma treatment in order to improve adhesion to the pressure-sensitive adhesive layer. A surface treatment such as the like 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. The thickness is usually preferably 20 to 450 μm, particularly preferably 25 to 250 μm, and more preferably 50 to 150 μm.

3. Peeling sheet

Even if a release sheet is laminated on the surface of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment on the side opposite to the substrate side to protect the pressure-sensitive adhesive layer until the pressure-sensitive adhesive sheet for stealth dicing is used, good night.

Although it does not specifically limit as a release sheet, For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a 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, poly A carbonate film, a polyimide film, a fluororesin film, etc. can be used. Moreover, you may use these crosslinked films. Further, a laminated film in which a plurality of such films is laminated may be used.

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

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

4. Adhesion

In the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment, the adhesive strength to the silicon mirror wafer at 23°C is preferably 1 N/25 mm or more, particularly preferably 2 N/25 mm or more. Moreover, it is preferable that the said adhesive force is 30 N/25 mm or less, and it is especially preferable that it is 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 is easy to hold the semiconductor wafer or the semiconductor chip to be obtained at a predetermined position, and the portion of the modified layer of the semiconductor wafer is well separated. be able to do In the case where the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive, the adhesive strength refers to the adhesive strength before energy ray irradiation. In addition, adhesive force means what was measured according to the method mentioned later.

In the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment, when the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive, the adhesive force to the silicon mirror wafer after energy ray irradiation at 23 ° C. is preferably 10 mN / 25 mm or more , particularly preferably 20 mN/25 mm or more. Moreover, it is preferable that the said adhesive force is 1000 mN/25 mm or less, and it is especially preferable that it is 900 mN/25 mm or less. After the semiconductor wafer has been sliced into pieces, the pressure-sensitive adhesive sheet for stealth dicing is irradiated with energy rays so that the adhesive force can be reduced to the above range, and thus the obtained semiconductor chips can be easily picked up. In addition, adhesive force means what was measured according to the method mentioned later.

The above-mentioned adhesive strength at 23°C and adhesive strength after energy ray irradiation at 23°C can be measured according to the following method. First, a sheet for semiconductor processing is cut to a width of 25 mm, and the surface on the pressure-sensitive adhesive layer side is attached to a silicon mirror wafer. This pasting can be performed using a laminator (manufactured by Lintec Corporation, product name "RAD-3510F/12") under conditions of a pasting speed of 10 mm/s, a wafer protrusion amount of 20 µm, and a roller pressure of 0.1 MPa. Subsequently, the obtained laminate of the sheet for semiconductor processing and the silicon mirror wafer is left to stand for 20 minutes in an atmosphere of 23°C and 50% RH. Here, in the case of measuring the adhesive force after energy ray irradiation at 23 ° C., after leaving it for 20 minutes, an ultraviolet irradiation device (manufactured by Lintec Corporation, product name “RAD-2000m/12”) was used for the laminate, Ultraviolet (UV) irradiation (irradiance 230 mW/cm 2 , light quantity 190 mJ/cm 2 ) is applied to the substrate side of the sheet under a nitrogen atmosphere. After 20 minutes of standing or UV irradiation, the sheet was coated with a silicon mirror 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") in accordance with JIS Z0237. The value measured after peeling from the wafer is referred to as adhesive force (mN/25 mm).

5. Manufacturing method of adhesive sheet for stealth dicing

The manufacturing method of the adhesive sheet for stealth dicing concerning this embodiment is not specifically limited, A conventional method can be used. As a first example of the above production method, first, a pressure-sensitive adhesive composition containing the material of the pressure-sensitive adhesive layer and a composition for coating containing a solvent or a dispersion medium as desired are prepared. Next, this composition for coating is applied onto the release surface of the release sheet by a die coater, curtain coater, spray coater, slit coater, knife coater or the like to form a coating film. In addition, the coating film is dried to form an adhesive layer. Then, the adhesive sheet for stealth dicing is obtained by bonding together the adhesive layer on the peeling sheet and the base material. The composition for coating is not particularly limited in properties as long as it can be applied. The component for forming the pressure-sensitive adhesive layer may be contained as a solute in the coating composition, or may be contained as a dispersoid.

When the composition for coating contains a crosslinking agent (E), the above drying conditions (temperature, time, etc.) may be changed or heat treatment may be separately provided in order to form a crosslinked structure at a desired density. In order to sufficiently advance the crosslinking reaction, usually, after laminating the pressure-sensitive adhesive layer on the base material by the above method or the like, the obtained pressure-sensitive adhesive sheet for stealth dicing is left for several days in an environment of, for example, 23 ° C. and 50% relative humidity. do nursing

As a second example of the manufacturing method of the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment, first, the composition for coating is applied to one surface of a substrate to form a coating film. Next, the coating film is dried to form a laminate composed of the base material and the pressure-sensitive adhesive layer. Further, in this laminate, the exposed surface of the pressure-sensitive adhesive layer and the release surface of the release sheet are bonded together. Thereby, the adhesive sheet for stealth dicing in which the peeling sheet was laminated|stacked on the 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 the adhesive layer of the above-described adhesive sheet for stealth dicing (the adhesive sheet for stealth dicing according to the present embodiment) to a semiconductor wafer, and a semiconductor wafer A modified layer formation step of forming a modified layer therein, and an expand step of expanding the pressure-sensitive adhesive sheet for stealth dicing in a room temperature environment to cut and separate the semiconductor wafer having the modified layer formed therein into individual chips.

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 former case, in the modified layer formation step, the laser beam is irradiated to the semiconductor wafer bonded to the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment. In the latter case, in the modified layer formation step, for example, a laser beam is irradiated to a semiconductor wafer bonded to another pressure-sensitive adhesive sheet (for example, a back grind sheet).

According to the method for manufacturing a semiconductor device according to the present embodiment, at least in the expand step, since the above-described adhesive sheet for stealth dicing is used, in the expand step, the interface between the adhesive sheet for stealth dicing and the semiconductor wafer is less likely to be displaced. It gets difficult. As a result, the force for pulling the semiconductor wafer in the periphery direction, which is generated by the expansion of the pressure-sensitive adhesive sheet for stealth dicing, tends to concentrate on the modified layer, and the semiconductor wafer can be divided favorably in the modified layer. For this reason, even when the chip size to be obtained is small, occurrence of splitting defects or chip breakage problems can be suppressed, and well-segmented chips can be obtained.

Further, in the method for manufacturing a semiconductor device according to the present embodiment, an adhesive film (DAF, NCF, etc.) You may further provide a lamination process of laminating|stacking. According to the manufacturing method of the semiconductor device concerning this embodiment, the adhesive film can be satisfactorily divided by the expand process.

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

(1) bonding process

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

(2) Laminate process

Next, a lamination step of laminating an adhesive film may be performed on the side opposite to the side of the adhesive sheet for stealth dicing in the semiconductor wafer bonded to the adhesive sheet for stealth dicing. This lamination is usually performed by heat lamination (thermal lamination). When a semiconductor wafer has electrodes on its surface, the adhesive film is laminated on the electrode side of the semiconductor wafer because electrodes are usually present on the surface opposite to the side of the pressure-sensitive adhesive sheet for stealth dicing in the semiconductor wafer.

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

(3) Modified layer formation process

Preferably, a modified layer forming step for forming a modified layer inside the semiconductor wafer is performed after the bonding step or the lamination step, but the modified layer forming step may be performed before this step. The modified layer forming step is usually performed by irradiating infrared laser light so as to be focused on a focal point set inside the semiconductor wafer (stealth dicing process). Laser beam irradiation may be performed on either side of the semiconductor wafer. If the modified layer formation step is performed after the lamination step, it is preferable to irradiate the laser beam over the pressure-sensitive adhesive sheet for stealth dicing. In addition, when the modified layer forming step is performed between the bonding step and the lamination step, or when the lamination step is not performed, it is preferable to directly irradiate the semiconductor wafer with laser light without passing through an adhesive sheet for stealth dicing.

(4) Expand process

After the modified layer formation step, the expand step of cutting and separating the semiconductor wafer is performed by expanding the pressure-sensitive adhesive sheet for stealth dicing in a room temperature environment. Thereby, on the adhesive layer of the adhesive sheet for stealth dicing, the semiconductor chip formed by dividing a semiconductor wafer is stuck. In the case where an adhesive film is laminated on the semiconductor wafer, the adhesive film is also divided simultaneously with the division of the semiconductor wafer by the expanding process to obtain a chip having an adhesive layer.

Specific conditions in the expand process are not limited. For example, the temperature at the time of expanding the pressure-sensitive adhesive sheet for stealth dicing can be a general expand temperature, and as described above, it is usually preferably 5 ° C. or higher, particularly preferably 10 ° C. or higher, and It is preferable that it is 15 degreeC or more. The temperature is preferably 45°C or less normally, particularly preferably 40°C or less, and more preferably 35°C or less.

(5) Shrink process

When sagging occurs in the peripheral region of the pressure-sensitive adhesive sheet for stealth dicing (the region between the ring frame and the chip group in plan view) by the expand step, a shrink step of heating the peripheral region is preferably performed. By heating the peripheral area of the pressure-sensitive adhesive sheet for stealth dicing, the base material located in the peripheral area shrinks, and the amount of sagging of the pressure-sensitive adhesive sheet for stealth dicing caused in the expanding process can be reduced. The heating method in the shrink process is not limited. Hot air may be sprayed, infrared rays may be irradiated, or microwaves may be irradiated.

(6) pick-up process

In the case of performing the shrink process, after the shrink process, after the expand process in the case of not performing the shrink process, the chips adhered to the adhesive sheet for stealth dicing are individually picked up from the adhesive sheet for stealth dicing, and the chips are semiconductor devices A pick-up process obtained as

Here, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing is made of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer is irradiated with energy rays to cure the pressure-sensitive adhesive layer at any stage after the bonding step and before the pick-up step to lower the adhesive strength desirable. Thereby, the pickup of the above chip can be performed more easily.

Examples of energy rays include ionizing radiation, ie, X-rays, ultraviolet rays, and electron beams. Among these, ultraviolet rays, which are relatively easy to introduce into an irradiation facility, are preferable.

When using ultraviolet rays as ionizing radiation, it is good to use near-ultraviolet rays including ultraviolet rays with a wavelength of about 200 to 380 nm because of ease of handling. The amount of light of ultraviolet rays may be appropriately selected depending on the type of energy ray-curable pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer or the thickness of the pressure-sensitive adhesive layer, and is usually about 50 to 500 mJ/cm 2 , preferably 100 to 450 mJ/cm 2 , and 150 to 400 mJ/cm 2 is more preferred. In addition, the ultraviolet ray illuminance is usually about 50 to 500 mW/cm 2 , preferably 100 to 450 mW/cm 2 and more preferably 150 to 400 mW/cm 2 . The ultraviolet light source is not particularly limited, and for example, a high-pressure mercury lamp, a metal halide lamp, a light emitting diode (LED), or the like is used.

In the case of using electron beams as ionizing radiation, the acceleration 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 desirable that the degree In addition, the irradiation dose may be appropriately selected according to the type of energy ray-curable pressure-sensitive adhesive included in the pressure-sensitive adhesive layer or the thickness of the pressure-sensitive adhesive layer, and is usually selected in the range of 10 to 1000 krad. The electron source is not particularly limited, and for example, a Cockcroft-Walton type, a Van de Graaff type, a resonance transformer type, an insulating core transformer type, or a straight type, a dynamitron type. Various types of electron beam accelerators, such as type and high frequency type, can be used.

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

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

Example

Hereinafter, the present invention will be described more specifically by 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 pressure-sensitive adhesive composition

80 mol% of the acrylic copolymer obtained by reacting 2-ethylhexyl acrylate/isobornyl acrylate/2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and its 2-hydroxyethyl acrylate Methacryloyloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 1.07 parts by mass were mixed in a solvent to obtain an adhesive composition.

(2) Manufacture of pressure-sensitive adhesive sheet for stealth dicing

The above adhesive composition was applied onto the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET3811"). Then, drying by heating was performed, and the coating film of the adhesive composition was made into an adhesive layer. The thickness of this pressure-sensitive adhesive layer was 10 µm. Thereafter, the pressure-sensitive adhesive layer on the release sheet obtained and the corona-treated side of the ethylene-methacrylic acid copolymer (EMAA) film (thickness: 80 μm, surface tension of the corona-treated side: 54 mN/m) corona-treated on one side as a base material By bonding together, an adhesive sheet for stealth dicing was obtained.

[Example 2]

80 mol% of the acrylic copolymer obtained by reacting 2-ethylhexyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and the 2-hydroxyethyl acrylate Methacryloyloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 1.07 parts by mass were mixed in a solvent to obtain an adhesive composition. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Example 3]

An acrylic copolymer obtained by reacting butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate = 42/30/28 (mass ratio) with 80 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate Iloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 1.07 parts by mass were mixed in a solvent to obtain an adhesive composition. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Example 4]

An acrylic copolymer obtained by reacting butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate = 42/30/28 (mass ratio) with 70 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate Iloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 0.43 parts by mass was mixed in a solvent to obtain an adhesive composition. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Example 5]

An acrylic copolymer obtained by reacting lauryl acrylate/methyl methacrylate/2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and 80 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate Royloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 1.07 parts by mass were mixed in a solvent to obtain an adhesive composition. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Comparative Example 1]

An acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 80/5/15 (mass ratio) with 80 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate An energy ray curable polymer was obtained by reacting yloxyethyl isocyanate (MOI). 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 (value in terms of solid content; hereinafter similarly denoted), 3 parts by mass of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator, and tolylene diisocyanate as a crosslinking agent 0.49 parts by mass of a system crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain an adhesive composition. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Comparative Example 2]

An acrylic copolymer obtained by reacting 2-ethylhexyl acrylate/vinyl acetate/2-hydroxyethyl acrylate = 60/20/20 (mass ratio) and 80 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate Royloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 0.31 mass part was mixed in a solvent, and the adhesive composition was obtained. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Comparative Example 3]

An acrylic copolymer obtained by reacting butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate = 62/10/28 (mass ratio) with 80 mol% of methacrylic acid based on the 2-hydroxyethyl acrylate Iloxyethyl isocyanate (MOI) was reacted to obtain an energy ray curable polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray curable polymer and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "IRGACURE 184") as a photopolymerization initiator and a tolylene diisocyanate-based crosslinking agent (manufactured by Toyo Ink, product name) as a crosslinking agent "Coronate L") 1.61 mass parts were mixed in a solvent, and the adhesive composition was obtained. Except using the obtained adhesive composition, it carried out similarly to Example 1, and manufactured the adhesive sheet for stealth dicing.

[Test Example 1] (measurement of shear force)

An instant adhesive (manufactured by TOAGOSEI CO., LTD., product name "Aron Alpha") was used on the side opposite to the adhesive layer in the base material of the adhesive sheet for stealth dicing obtained in Examples and Comparative Examples, as a bonding material A laminate was obtained by adhering a polyethylene terephthalate film (thickness: 100 μm).

After cutting the obtained layered product 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%, the release sheet was peeled off from the pressure-sensitive adhesive layer, and this was used as a sample. This sample was attached to the mirror surface of a silicon mirror wafer (thickness: 350 μm) through an adhesive layer under an environment of a temperature of 23° C. and a relative humidity of 50%. At this time, a 2 kg roller was reciprocated once to apply a load to the sample so that a 3 mm portion of the sample in the longitudinal direction was adhered to the silicon 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 the cut piece of the sample that became unnecessary was peeled off from the silicon mirror wafer. As a result, as shown in FIGS. 1 and 2 , a test object in which the sample and the silicon mirror wafer were adhered in an area of 20 mm x 3 mm (60 mm 2 ) was obtained. 1 and 2, reference numeral 1 denotes an adhesive sheet (sample) for stealth dicing having a backing material, 2 a silicon mirror wafer, 11 a base material, 12 an adhesive layer, and 13 a backing material.

After 20 minutes from the application, a tensile test was performed using an autograph (manufactured by IMADA SEISAKUSHO CO., LTD., product name "SDT-203NB-50 R3") under conditions of a tensile speed of 1 mm/min in an environment of 23 ° C. and the shear 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)

For the substrates used in Examples and Comparative Examples, the storage modulus (MPa) of the substrates at 23°C was measured under the following equipment and conditions. The results are shown in Table 1.

Measuring device: TA Instruments' dynamic modulus measuring device "DMA Q800"

Test start temperature: 0°C

Test end temperature: 200°C

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

[Test Example 3] (Measurement of storage modulus of pressure-sensitive adhesive layer)

The pressure-sensitive adhesive composition used in Examples and Comparative Examples was applied to the release surface of a release sheet to form an adhesive layer, and the release surface of the separately prepared release sheet was pressed against the exposed pressure-sensitive adhesive layer to form a release sheet/adhesive layer/ An adhesive sheet made of a release sheet was produced. The release sheet was removed from the pressure-sensitive adhesive sheet, and a plurality of pressure-sensitive adhesive layers were laminated to a thickness of 200 µm. A 30 mm × 4 mm rectangle (thickness: 200 µm) was punched through the resulting laminated body of the pressure-sensitive adhesive layer, and this was used as a sample for measurement. About this measurement sample, the storage elastic modulus (kPa) of the adhesive layer at 23 degreeC was measured on the following apparatus and conditions. The results are shown in Table 1.

Measuring device: TA Instruments' dynamic modulus measuring device "DMA Q800"

Distance between measurements: 20 mm

Test start temperature: -30℃

Test end temperature: 120°C

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

[Test Example 4] (Evaluation of splitting property)

A 6-inch ring frame and a mirror surface of a 6-inch silicon mirror wafer (thickness: 150 μm) were affixed to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing obtained in Examples and Comparative Examples. Next, using a stealth dicing device (manufactured by DISCO Corporation, product name "DFL7360"), a laser was irradiated to the surface opposite to the pressure-sensitive adhesive sheet for stealth dicing on a 6-inch silicon mirror wafer under the following conditions, , a modified layer was formed in a 6-inch silicon mirror wafer. Laser irradiation at this time was performed twice so that the sizes of the chips obtained were 8 mm x 8 mm and 4 mm x 4 mm, respectively.

<Conditions of investigation>

Irradiation height: 100 μm from the tape side

Frequency: 90Hz

Output: 0.25W

Machining speed: 360mm/sec

Thereafter, using an expander (manufactured by JCM, product name "ME-300 B"), the workpiece was expanded at a drawing speed of 100 mm/sec and a drawing amount of 10 mm in a 23°C environment. . Next, the number of chips that were well separated at the position of the modified layer and completely separated from the surrounding chips was counted, and the ratio (%) to the total number of theoretically obtained chips was calculated. Then, the splitting property was evaluated based on the following criteria. The results are shown in Table 1.

○: The ratio is 100%.

(triangle|delta): The said ratio is less than 100% and 80% or more.

x: The ratio is less than 80%.

As can be seen from Table 1, the pressure-sensitive adhesive sheet for stealth dicing obtained in the examples can well divide the wafer on which the modified layer is formed by expanding, and in particular, has a chip size of 8 mm × 8 mm or 4 mm × Even in the case of a small size such as 4 mm, excellent partitioning properties were exhibited.

The pressure-sensitive adhesive sheet for stealth dicing according to the present invention is suitably used in a semiconductor device manufacturing method in which an expand step is performed at room temperature.

1: Adhesive sheet for stealth dicing with backing material (sample)
11: registration
12: adhesive layer
13: wiring material
2: silicon mirror wafer

Claims (8)

An 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,
A substrate and an adhesive layer laminated on one side of the substrate,
The substrate is a single layer,
When the pressure-sensitive adhesive sheet for stealth dicing is attached to a silicon wafer through the pressure-sensitive adhesive layer, the shear force at the interface between the pressure-sensitive adhesive layer and the silicon wafer at 23 ° C. exceeds 70 N / (3 mm × 20 mm) 250 N / (3 mm × 20 mm) or less, characterized in that the pressure-sensitive adhesive sheet for stealth dicing. According to claim 1,
The pressure-sensitive adhesive sheet for stealth dicing, characterized in that the chip has a minimum side length of 2 mm or more and 30 mm or less. According to claim 1,
The adhesive sheet for stealth dicing, characterized in that the semiconductor wafer has a thickness of 10 μm or more and 1000 μm or less. According to claim 1,
The pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive, characterized in that, the pressure-sensitive adhesive sheet for stealth dicing. According to claim 1,
The pressure-sensitive adhesive sheet for stealth dicing, characterized in that the storage modulus at 23 ° C. of the substrate 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 5 and a semiconductor wafer;
A modified layer forming step of forming a modified layer inside the semiconductor wafer, and
An expand step of expanding the pressure-sensitive adhesive sheet for stealth dicing under a room temperature environment to cut and separate the semiconductor wafer having a modified layer therein into individual chips;
A method of manufacturing a semiconductor device comprising: According to claim 6,
Manufacturing of a semiconductor device, characterized by further comprising a lamination step of laminating an adhesive film on a surface opposite to the side of the adhesive sheet for stealth dicing in the semiconductor wafer bonded to the adhesive sheet for stealth dicing. method. According to claim 1,
The pressure-sensitive adhesive sheet for stealth dicing, characterized in that the side of the pressure-sensitive adhesive layer opposite to the base material is directly adhered to a semiconductor wafer.