JP7062655B2 - Manufacturing method of adhesive sheet for stealth dicing and semiconductor device - Google Patents

Description

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

When manufacturing a chip-shaped semiconductor device from a semiconductor wafer, conventionally, blade dicing processing is performed to obtain a chip by cutting the semiconductor wafer with a rotary blade while spraying a liquid for cleaning or the like on the semiconductor wafer. It was common. However, in recent years, stealth dicing processing, which is a dry type and can be divided into chips, 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), and the damage to the vicinity of the surface of the semiconductor wafer is minimized while preliminarily inside the semiconductor wafer. Form a modified layer. Then, by expanding the dicing sheet, a force is applied to the semiconductor wafer to cut and separate the individual chips.

In recent years, there has been a demand for laminating another chip on a chip manufactured as described above or for adhering the chip on 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 forming surface of the chip provided with the protruding electrode and the circuit on another chip or the substrate In some fields, flip-chip mounting in which the electrodes are directly connected to each other and the transition to the Through Silicon Via (TSV) is being carried out. In response to the demand for chip lamination and bonding in such flip chip mounting and the like, a method of fixing a chip with an electrode to another chip or a film substrate by using an adhesive has been proposed.

Then, in order to easily apply to such applications, in the process of the above manufacturing method, for a semiconductor wafer with an electrode or a modified semiconductor wafer with an electrode to which a dicing sheet is attached to a surface opposite to the electrode forming surface. It has been proposed that a film-like adhesive is laminated on the electrode forming surface, and the electrode-attached chips divided by the expanding step are provided with an adhesive layer on the electrode forming surface. As such an adhesive layer, a die attach film (DAF) or an adhesive film called a nonconductive film (NCF) is used.

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

Japanese Unexamined Patent Publication No. 2005-19962

Since the above-mentioned DAF and NCF have the property of becoming brittle in a low temperature region, in order to improve the splittability of the DAF and NCF, a cool expand step in which the above expansion is carried out in a low temperature environment of about -20 ° C to 10 ° C is performed. There is more to do.

However, in order to perform the cool expand process, it is necessary to introduce equipment capable of realizing temperature control, so that the initial cost is higher than that in the case of expanding at room temperature. Therefore, from the viewpoint of cost, it is desirable to perform the expansion at room temperature instead of the cool expanding step.

The present invention has been made in view of the above-mentioned actual conditions, and is a stealth dicing pressure-sensitive adhesive sheet and a semiconductor capable of satisfactorily individualizing a semiconductor wafer into a chip even when expanding at room temperature. It is an object of the present invention to provide a method of manufacturing an apparatus.

In order to achieve the above object, firstly, the present invention is a stealth dicing pressure-sensitive adhesive sheet used at least for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips in a room temperature environment. The stealth dicing pressure-sensitive adhesive sheet is attached to a silicon wafer via the pressure-sensitive adhesive layer, which comprises a base material and a pressure-sensitive adhesive layer laminated on one surface side of the base material. Provided is a pressure-sensitive adhesive sheet for stealth dicing, characterized in that the shearing force at an interface between the pressure-sensitive adhesive layer and the silicon wafer at 23 ° C. is 70 N / (3 mm × 20 mm) or more and 250 N / (3 mm × 20 mm) or less. (Invention 1).

In the adhesive sheet for stealth dicing according to the above invention (Invention 1), the shearing force at 23 ° C. is within the above range, so that the adhesive sheet for stealth dicing and the adhesive sheet for stealth dicing are used when expanding at room temperature. Misalignment at the interface with the semiconductor wafer laminated on top is less likely to occur. As a result, the force that pulls the semiconductor wafer toward the peripheral edge thereof, which is generated by the expansion of the adhesive sheet for stealth dicing, tends to be concentrated on the modified layer, and as a result, the semiconductor wafer is well divided in the modified layer. Therefore, even when expanding at room temperature, problems such as poor division and chip breakage are suppressed, and a chip that is well separated can be obtained.

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

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

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

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

Secondly, the present invention comprises a bonding step of bonding the pressure-sensitive adhesive layer of the stealth dicing pressure-sensitive adhesive sheet (Inventions 1 to 5) and a semiconductor wafer, and a modification of forming a modified layer inside the semiconductor wafer. It is characterized by including a quality layer forming step and an expanding step of expanding the adhesive sheet for stealth dicing in a room temperature environment and cutting and separating the semiconductor wafer having a modified layer formed therein into individual chips. (Invention 6).

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

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for manufacturing a pressure-sensitive adhesive sheet for stealth dicing and a semiconductor device capable of satisfactorily individualizing a semiconductor wafer into chips even when expanding at room temperature.

It is a top view explaining the measuring method of the shear force which concerns on Test Example 1. FIG. It is sectional drawing explaining the measuring method of the shear force which concerns on Test Example 1. FIG.

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 a semiconductor wafer having a modified layer formed therein into individual chips in 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 further 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 further preferably an environment of 35 ° C. or lower. Since the above temperature range can be easily achieved without intentionally controlling the temperature, it is possible to reduce the cost of stealth dicing. In addition, the concept of "tape" is also included in "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 surface side of the base material. The substrate and the pressure-sensitive adhesive layer are preferably, but not limited to, directly laminated.

When the stealth dicing pressure-sensitive adhesive sheet is attached to a silicon wafer via 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 , 70 N / (3 mm × 20 mm) or more, 250 N / (3 mm × 20 mm) or less.

The stealth dicing pressure-sensitive adhesive sheet according to the present embodiment has the shearing force as described above, so that when the stealth dicing pressure-sensitive adhesive sheet on which the semiconductor wafer provided with the modified layer is laminated is expanded at room temperature. Misalignment at the interface between the adhesive sheet for stealth dicing and the semiconductor wafer is unlikely to occur. Therefore, the force of pulling the semiconductor wafer in the peripheral portion direction generated by the expansion of the adhesive sheet for stealth dicing is less likely to be impaired. As a result, the force is likely to be concentrated on the modified layer, and the semiconductor wafer is satisfactorily divided in the modified layer. As described above, even when expanding at room temperature, problems such as poor division and chip breakage are suppressed, and a chip that is well separated can be obtained.

Further, when the shearing force is less than 70 N / (3 mm × 20 mm), especially when the chip size is small, the interface between the stealth dicing pressure-sensitive adhesive sheet and the semiconductor wafer is likely to be displaced during expansion, and the semiconductor wafer is likely to be displaced. Cannot be cut and separated well. On the other hand, when the shearing force exceeds 250 N / (3 mm × 20 mm), sufficient tack is not developed in the stealth dicing pressure-sensitive adhesive sheet, and the obtained chips cannot be well held on the stealth dicing pressure-sensitive adhesive sheet. ..

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

When a semiconductor wafer having a modified layer formed inside is cut and separated into individual chips in a room temperature environment using the adhesive sheet for stealth dicing according to the present embodiment, the obtained chips have the minimum side length. The length is preferably 2 mm to 30 mm, particularly preferably 2.5 mm to 25 mm, and further preferably 3 mm to 20 mm.

Further, when the semiconductor wafer having the modified layer formed inside is cut and separated into individual chips in a room temperature environment by using the adhesive sheet for stealth dicing according to the present embodiment, the thickness of the semiconductor wafer is increased. The thickness is preferably 10 μm to 1000 μm or less, particularly preferably 20 μm to 950 μm or less, and further preferably 30 μm to 900 μm or less.

As described above, according to the adhesive sheet for stealth dicing according to the present embodiment, when expanding at room temperature, the displacement at the interface between the adhesive sheet for stealth dicing and the semiconductor wafer is suppressed, and the semiconductor wafer is cut satisfactorily. Can be separated. Therefore, the adhesive sheet for stealth dicing according to the present embodiment is suitable for producing a chip having the above-mentioned chip size at low cost.

1. 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-mentioned shearing force. The pressure-sensitive adhesive layer may be composed of a non-energy ray-curable pressure-sensitive adhesive or an energy ray-curable pressure-sensitive adhesive. The non-energy ray-curable pressure-sensitive adhesive preferably has desired adhesive strength and re-peelability, and is, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, or a polyester-based pressure-sensitive adhesive. , Polyvinyl ether adhesives and the like can be used. Among these, an acrylic pressure-sensitive adhesive that can effectively suppress the falling off of semiconductor wafers, chips, etc. in the modified layer forming step, the expanding step, or the like is preferable.

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

The energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be mainly composed of a polymer having energy ray-curing property, or a non-energy ray-curable polymer (polymer having no energy ray-curing property). It may be mainly composed of a mixture of a monomer having at least one energy ray-curable group and / or an oligomer. It may also be a mixture of an energy ray curable polymer and a non-energy ray curable polymer, a monomer having an energy ray curable polymer and at least one energy ray curable group, and / or. It may be a mixture with an oligomer or a mixture of three kinds thereof.

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 polymer having energy ray curability is a (meth) acrylic acid ester (co) polymer (A) in which a functional group (energy ray curable group) having energy ray curability is introduced into the side chain (hereinafter referred to as “energy ray curable”). It may be referred to as "curable polymer (A)"). This energy ray-curable polymer (A) reacts 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 preferable that it is obtained by allowing it to be obtained. In addition, in this specification, (meth) acrylic acid ester means both acrylic acid ester and 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 constituent 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 and an epoxy group in the molecule. It is preferable that the monomer is contained in.

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 are used alone or in combination of two or more.

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 the alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms, for example, an alicyclic structure in the molecule is formed. A monomer having an alicyclic structure (monomer containing an alicyclic structure) is preferably used.

As the alkyl (meth) acrylate, an alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl ( Meta) acrylate, 2-ethylhexyl (meth) acrylate and the like are preferably used. These may be used individually by 1 type, or may be used in combination of 2 or more type.

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

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 further preferably 10 to 25% by mass. contains. Further, the acrylic copolymer (a1) contains a structural unit derived from the (meth) acrylic acid ester monomer or a derivative thereof, preferably 50 to 99% by mass, particularly preferably 60 to 95% by mass, still more preferably 70. It is contained in a proportion of about 90% by mass.

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

An energy ray-curable polymer (A) is obtained 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. ) Is obtained.

The functional group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of the 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 hydroxy group, an amino group or a substituted amino group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group, and acrylic. When the functional group of the system copolymer (a1) is an epoxy group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxy group or an aziridinyl group.

Further, 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 such an unsaturated group-containing compound (a2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1-(. Bisacrylloyloxymethyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with a hydroxyethyl (meth) acrylate; a diisocyanate compound or a polyisocyanate compound, a polyol compound, and a hydroxyethyl (meth). Acryloyl monoisocyanate compound obtained by reaction with acrylate; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl- 2-Oxazoline and the like can be mentioned.

The unsaturated group-containing compound (a2) is preferably 50 to 95 mol%, particularly preferably 60 to 93 mol%, more preferably 60 to 93 mol%, based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). It is used in a proportion of 70-90 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) are used. Depending on the combination, the reaction temperature, pressure, solvent, time, presence / absence of catalyst, and type of polymer 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 contained in the acrylic copolymer (a1). It is introduced into the side chain to obtain an energy ray-curable polymer (A).

The weight average molecular weight (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 further 200,000 to 100. It is preferably 10,000. The weight average molecular weight (Mw) in the present specification is a value in terms of standard polystyrene measured by a gel permeation chromatography method (GPC method).

Even when the energy ray-curable pressure-sensitive adhesive contains a polymer having energy ray-curable properties 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 a polyhydric alcohol and (meth) acrylic acid can be used.

Examples of the energy ray-curable monomer and / or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, trimethyl propanthry (meth) acrylate, and penta. Elythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol Examples thereof include polyfunctional acrylic acid esters such as di (meth) acrylate and dimethylol tricyclodecanedi (meth) acrylate, polyester oligo (meth) acrylate, and polyurethane oligo (meth) acrylate.

When the energy ray-curable monomer and / or oligomer (B) is blended with the energy ray-curable polymer (A), the energy ray-curable monomer and / or oligomer (B) in the energy ray-curable pressure-sensitive adhesive. ) 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 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 can be reduced.

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

The photopolymerization initiator (C) is an energy ray-curable polymer (A) (in the case of blending an energy ray-curable monomer and / or an oligomer (B), the energy ray-curable polymer (A) and energy. 100 parts by mass of the total amount of the linear curable monomer and / or oligomer (B)) 0.1 to 10 parts by mass, particularly 0.5 to 6 parts by mass with respect to 100 parts by mass. Is preferable.

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

Examples of the non-energy ray-curable polymer component or oligomer component (D) include polyacrylic acid esters, polyesters, polyurethanes, polycarbonates, polyolefins, highly branched polymers, and the like, and have a weight average molecular weight (Mw) of 30 to 2.5 million. Polymers or oligomers are preferred. By blending the component (D) with an energy ray-curable pressure-sensitive adhesive, the adhesiveness and peelability before curing, the strength after curing, the easy peeling property from an adherend, the adhesiveness with other layers, and the storage It can improve stability and so on. 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 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, etc. Examples thereof include reactive phenolic resins. By blending the cross-linking agent (E) with the energy ray-curable pressure-sensitive adhesive, the above-mentioned shearing force can be adjusted.

The blending amount of the cross-linking agent (E) is preferably 0.01 to 8 parts by mass, particularly 0.04 to 5 parts by mass with respect 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. When the energy ray-curable pressure-sensitive adhesive contains a polymerizable branched polymer, it is possible to suppress the transfer of organic substances from the pressure-sensitive adhesive layer to the semiconductor wafer or semiconductor chip laminated on the pressure-sensitive adhesive sheet for stealth dicing, and stealth. In the process of individually picking up semiconductor chips from the 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 an effect, the polymerizable branched polymer (F) has an interface with a semiconductor wafer or a semiconductor chip in the pressure-sensitive adhesive layer. It is considered that the polymer tends to be present in the vicinity, and the polymerizable branched polymer (F) is exposed to the energy ray-curable polymer (A), the energy ray-curable monomer and / or There is a possibility that polymerization with the oligomer (B) has an effect.

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 radically polymerizable double bonds in the molecule, an active hydrogen group, and one radically polymerizable product are obtained. A polymer having a branched structure is obtained by polymerizing a monomer having a double bond in the molecule and a monomer having one radically polymerizable double bond in the molecule. Next, the obtained polymer is reacted with a functional group capable of reacting with the active hydrogen group of the polymer to form a bond and a compound having at least one radically polymerizable double bond in the molecule. As a result, 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) appropriately suppresses the interaction with the energy ray-curable polymer (A), the energy ray-curable monomer and / or the 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.

The content of the polymerizable branched polymer (F) in the pressure-sensitive adhesive layer is not particularly limited, but is usually energy ray-cured 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 preferably 0.1 part by mass or more with respect 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 the semiconductor chip with the pressure-sensitive adhesive layer. Since these 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 size of 0.20 μm or more remaining on the 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 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, 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 contains a mixture of a non-energy ray-curable polymer component and a monomer and / or an oligomer having at least one energy ray-curable group as a main component will be described below. ..

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

As the monomer and / or oligomer having at least one energy ray-curable group, the same one as the above-mentioned component (B) can be selected. The compounding ratio of the non-energy ray-curable polymer component to the monomer and / or oligomer having at least one energy ray-curable group 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 blended in the same manner as described above.

The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as it can function appropriately 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 pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment preferably has a storage elastic modulus at 23 ° C. of 1 to 5000 kPa, particularly preferably 3 to 3000 kPa, and further preferably 5 to 2500 kPa. Is preferable. When the storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. is within the above range, the pressure-sensitive adhesive sheet for stealth dicing becomes easy to expand, and the chips can be satisfactorily divided. The method for measuring the storage elastic modulus is as shown in a test example described later.

2. 2. Base material The base material in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment preferably has a storage elastic modulus of 10 MPa or more and 600 MPa or less at 23 ° C. When the shearing force of the pressure-sensitive adhesive layer is in the above-mentioned range and the storage elastic modulus of the base material is in the above-mentioned range, stealth dicing is suppressed while suppressing the deviation at the interface between the pressure-sensitive adhesive sheet for stealth dicing and the semiconductor wafer. As a result of the pressure-sensitive adhesive sheet being sufficiently stretchable, the semiconductor wafer can be satisfactorily divided into chips. The method for measuring the storage elastic modulus is as shown in a 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 is efficiently used for stealth dicing. Adhesive sheets can be manufactured. Further, the handleability of the adhesive sheet for stealth dicing is also improved. On the other hand, when the storage elastic modulus is 600 MPa or less, the semiconductor wafer can be satisfactorily supported by the adhesive sheet for stealth dicing mounted on the ring frame.

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

When the modified layer forming step of irradiating the semiconductor wafer bonded to the stealth dicing pressure-sensitive adhesive sheet with laser light through the stealth dicing pressure-sensitive adhesive sheet is performed, the base in the stealth dicing pressure-sensitive adhesive sheet according to the present embodiment. It is preferable that the material exhibits excellent light transmittance with respect to the light having the wavelength of the laser light.

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

The base material in the pressure-sensitive adhesive sheet for stealth dicing according to the present embodiment preferably contains a film (resin film) whose main material is a resin-based material, and is particularly preferably composed of only a resin film. Specific examples of the resin film include ethylene-vinyl acetate copolymer film; ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) methyl acrylate copolymer film, and other ethylene- (meth) acrylic. Ethylene-based copolymer films such as acid ester copolymer films; polyolefin-based films such as polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, ethylene-norbornene copolymer films, norbornene resin films; polyvinyl chlorides. 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; (meth) acrylic acid ester copolymer film; polyurethane film; polyimide Films; polystyrene films; polycarbonate films; fluororesin films and the like. Examples of polyethylene films include low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) films, high density polyethylene (HDPE) films and the like. Further, modified films such as these crosslinked films and ionomer films are also used. The base material may be a film made of one of these types, or may be a film made of a material in which two or more types are combined. Further, it may be a laminated film having a multilayer structure in which a plurality of layers made of one or more of the above-mentioned materials are laminated. In this laminated film, the materials constituting each layer may be the same type or different types.

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

In the base material, the above film contains various additives such as fillers, flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. It may be. The content of these additives is not particularly limited, but is preferably in the 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 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 a primer in order to enhance the 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 function properly in the process in which the adhesive sheet for stealth dicing is used. The thickness is usually preferably 20 to 450 μm, particularly preferably 25 to 250 μm, and further preferably 50 to 150 μm.

3. 3. Peeling sheet In order to protect the adhesive layer on the surface of the adhesive sheet for stealth dicing according to the present embodiment, which is opposite to the base material side, until the adhesive sheet for stealth dicing is used. The release sheet may be laminated.

The release sheet is not particularly limited, and 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, and the like. 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 , Fluororesin film and 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 peeling surface (the surface having peelability; particularly the surface in contact with the pressure-sensitive adhesive layer) of the peeling sheet is subjected to a peeling 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 Strength In the adhesive sheet for stealth dicing according to the present embodiment, the adhesive strength with respect to the silicon mirror wafer at 23 ° C. is preferably 1N / 25 mm or more, and particularly preferably 2N / 25 mm or more. The adhesive strength is preferably 30 N / 25 mm or less, and particularly preferably 29.5 N / 25 mm or less. When the adhesive force at 23 ° C. is within the above range, when the adhesive sheet is expanded in the expanding step, it becomes easy to maintain the adhesive sheet in a predetermined position of the semiconductor wafer or the obtained semiconductor chip, and the semiconductor wafer is divided in the modified layer portion. Can be performed well. 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. The adhesive strength is measured by a method described later.

In the adhesive sheet for stealth dicing according to the present embodiment, when the adhesive layer is composed of an energy ray-curable adhesive, the adhesive force to the silicon mirror wafer after energy ray irradiation at 23 ° C. is 10 mN / 25 mm or more. It is preferably 20 mN / 25 mm or more. The adhesive strength 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. It becomes. The adhesive strength is measured by a method described later.

The above-mentioned adhesive force at 23 ° C. and the adhesive force after irradiation with energy rays at 23 ° C. can be measured by the following methods. First, the semiconductor processing sheet 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 sticking can be performed using a laminator (manufactured by Lintec Corporation, 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. Subsequently, the obtained laminate of the semiconductor processing sheet and the silicon mirror wafer is left to stand in an atmosphere of 23 ° C. and 50% RH for 20 minutes. Here, when measuring the adhesive strength after irradiation with energy rays at 23 ° C., after leaving it for 20 minutes, the laminated body is subjected to an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m / 12"). ) Is used to irradiate the sheet with ultraviolet rays (UV) (illuminance 230 mW / cm ² , light intensity 190 mJ / cm ² ) from the substrate side of the sheet in a nitrogen atmosphere. Following 20 minutes of standing or UV irradiation, a sheet is used with a universal tensile tester (AMD, product name "RTG-1225") at a peeling angle of 180 ° and a peeling speed of 300 mm / min according to JIS Z0237. Is peeled off from the silicon mirror wafer, and the measured value is defined as the adhesive strength (mN / 25 mm).

5. Method for Producing Adhesive Sheet for Stealth Dicing The method for producing the adhesive sheet for stealth dicing according to the present embodiment is not particularly limited, and a conventional method can be used. As a first example of the production method, first, a pressure-sensitive adhesive composition containing a material for a pressure-sensitive adhesive layer, and, if desired, a coating composition further containing a solvent or a dispersion medium are prepared. Next, this coating composition is applied onto the peeling 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 to each other to obtain a pressure-sensitive adhesive sheet for stealth dicing. The properties of the coating composition are 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 or heat treatment may be performed in order to form a cross-linked structure at a desired abundance density. It may be provided separately. In order to sufficiently proceed the cross-linking 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 placed in an environment of, for example, 23 ° C. and a relative humidity of 50%. Perform curing such as leaving it for several days.

As a second example of the method for producing a stealth dicing pressure-sensitive adhesive sheet according to the present 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 composed of a base material and an adhesive layer. Further, the exposed surface of the pressure-sensitive adhesive layer in this laminated body and the peeled surface of the release sheet are bonded together. As a result, a stealth dicing pressure-sensitive adhesive sheet in which a release sheet is laminated on the pressure-sensitive adhesive layer can be obtained.

[Manufacturing method of semiconductor device]
The 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 the present embodiment) and a semiconductor wafer. , The modified layer forming step of forming the modified layer inside the semiconductor wafer, and the adhesive sheet for stealth dicing expanded in the room temperature environment, and the semiconductor wafer having the modified layer formed inside is cut into individual chips. It includes an expanding step to separate.

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

According to the method for manufacturing a semiconductor device according to the present embodiment, since the above-mentioned stealth dicing pressure-sensitive adhesive sheet is used at least in the expanding step, the interface between the stealth dicing pressure-sensitive adhesive sheet and the semiconductor wafer is unlikely to be displaced in the expanding step. Become. As a result, the force that pulls the semiconductor wafer toward the peripheral edge, which is generated by the expansion of the adhesive sheet for stealth dicing, tends to be concentrated on the modified layer, and as a result, the semiconductor wafer is satisfactorily divided in the modified layer. Therefore, even when the obtained chip size is small, problems such as division failure and chip breakage are suppressed, and a chip that is well separated can be obtained.

Further, in the method for manufacturing a semiconductor device according to the present embodiment, an adhesive film (DAF, NCF, etc.) is used on a surface of a semiconductor wafer bonded to a stealth dicing pressure-sensitive adhesive sheet on a surface opposite to the stealth dicing pressure-sensitive adhesive sheet side. May further be provided with a laminating step of laminating. According to the method for manufacturing a semiconductor device according to the present embodiment, the adhesive film can be satisfactorily divided by the expanding step.

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

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

(2) Laminating Step Next, a laminating step may be performed in which the adhesive film is laminated on the surface of the semiconductor wafer bonded to the stealth dicing pressure-sensitive adhesive sheet on the side opposite to the stealth dicing pressure-sensitive adhesive sheet side. This laminating is usually performed by heat laminating (thermal laminating). When the semiconductor wafer has an electrode on the surface, the electrode is usually present on the surface of the semiconductor wafer opposite to the stealth dicing pressure-sensitive adhesive sheet side, so that the adhesive film is laminated on the electrode side of the semiconductor wafer.

The adhesive film may be any of DAF, NCF and the like, and usually has heat-sensitive adhesiveness. The material is not particularly limited, and specific examples thereof include a film-like member formed of 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, after the laminating step or the laminating step, a modified layer forming step of forming a modified layer inside the semiconductor wafer is performed, but the modified layer is formed before those steps. A forming step may be performed. The modified layer forming step is usually performed by irradiating a laser beam in the infrared region so as to be focused on a focal point set inside the semiconductor wafer (stealth dicing process). Irradiation of the laser beam 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 the laser beam through the adhesive sheet for stealth dicing. Further, when the modified layer forming step is performed between the bonding step and the laminating step, or when the laminating step is not performed, the laser beam is directly applied to the semiconductor wafer without using the adhesive sheet for stealth dicing. It is preferable to irradiate.

(4) Expanding Step After the modified layer forming step, an 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, a semiconductor chip formed by dividing the semiconductor wafer is attached onto the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for stealth dicing. When the adhesive film is laminated on the semiconductor wafer, the adhesive film is also divided at the same time as the semiconductor wafer is divided by the expanding step to obtain a chip with an adhesive layer.

The specific conditions in the expanding process are not limited. For example, the temperature at which the adhesive sheet for stealth dicing is expanded can be a general expanding temperature, and as described above, it is usually preferably 5 ° C. or higher, and particularly preferably 10 ° C. or higher. Further, it is preferably 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) Shrink step When the peripheral region of the adhesive sheet for stealth dicing (the region between the ring frame and the chip group in a plan view) becomes loose due to the expanding step, the shrink step heats the peripheral region. It is preferable to do. By heating the peripheral region of the stealth dicing pressure-sensitive adhesive sheet, the base material located in this peripheral region shrinks, and it becomes possible to reduce the amount of slack in the stealth dicing pressure-sensitive adhesive sheet generated 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.

(6) Pick-up process After the shrink process when the shrink process is performed, and after the expand process when the shrink process is not performed, the chips attached to the stealth dicing adhesive sheet are individually attached to the stealth dicing adhesive sheet. The pick-up process is performed to obtain the chip as a semiconductor device by picking up from.

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 at any stage after the bonding step and before the pick-up step. It is preferable to cure the pressure-sensitive adhesive layer and reduce the adhesive strength. This makes it easier to pick up the above chips.

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

When ultraviolet rays are used as ionizing radiation, near-ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm may be used for ease of 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 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 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.

When an electron beam is used as ionizing radiation, the acceleration voltage should be appropriately selected according to the type of energy ray-polymerizable group and energy ray-polymerizable compound contained in the pressure-sensitive adhesive layer and the thickness of the pressure-sensitive adhesive layer. It is preferable that the acceleration voltage is usually about 10 to 1000 kV. Further, the irradiation dose may be appropriately selected according to the type of the 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 quad. The electron beam source is not particularly limited, and for example, various electron beam accelerators such as cockloft Walton type, Van de Graaff type, resonance transformer type, insulated core transformer type, linear type, dynamistron type, and high frequency type are used. be able to.

By implementing the above manufacturing method, a semiconductor device can be manufactured by using the adhesive sheet for stealth dicing according to the present embodiment.

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

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

[Example 1]
(1) Preparation of Adhesive Composition An acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / isobornyl acrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and its 2 -Hydroxyethyl acrylate was reacted with 80 mol% methacryloyloxyethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 1.07 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive adhesive composition.

(2) Production of Adhesive Sheet for Stealth Dicing The above pressure-sensitive adhesive composition was applied onto the peeling surface of a release sheet (manufactured by Lintec Corporation, 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 thickness of this pressure-sensitive adhesive layer was 10 μm. Then, the pressure-sensitive adhesive layer on the obtained release sheet and the ethylene-methacrylic acid copolymer (EMAA) film having one surface treated with corona as a base material (thickness: 80 μm, surface tension of the corona-treated surface: 54 mN). By adhering it to the corona-treated surface of / m), an adhesive sheet for stealth dicing was obtained.

[Example 3]
The acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and 80 mol% with respect to the 2-hydroxyethyl acrylate. It was reacted with methacryloyloxyethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 1.07 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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]
Acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and 80 mol% methacryloyloxy with respect to the 2-hydroxyethyl acrylate. It was reacted with ethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 1.07 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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]
An acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and 70 mol% of methacryloyloxy with respect to the 2-hydroxyethyl acrylate. It was reacted with ethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 0.43 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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 5]
Acrylic copolymer obtained by reacting lauryl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 42/30/28 (mass ratio) and 80 mol% methacryloyloxy with respect to the 2-hydroxyethyl acrylate. It was reacted with ethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 1.07 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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 butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 80/5/15 (mass ratio) and 80 mol% methacryloyloxy with respect to the 2-hydroxyethyl acrylate. It was reacted with ethyl 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; hereinafter referred to in the same manner) and 1-hydroxycyclohexylphenylketone as a photopolymerization initiator (manufactured by BASF, product name "Irgacure 184") 3 A pressure-sensitive adhesive composition was obtained by mixing 0.49 parts by mass of a tolylene isocyanate-based cross-linking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") as a cross-linking agent 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]
The acrylic copolymer obtained by reacting 2-ethylhexyl acrylate / vinyl acetate / 2-hydroxyethyl acrylate = 60/20/20 (mass ratio) and 80 mol% with respect to the 2-hydroxyethyl acrylate. It was reacted with methacryloyloxyethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 0.31 part by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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 3]
Acrylic copolymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 62/10/28 (mass ratio) and 80 mol% methacryloyloxy with respect to the 2-hydroxyethyl acrylate. It was reacted with ethyl isocyanate (MOI) to obtain 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-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and tolylene diisocyanate as a cross-linking agent. 1.61 parts by mass of a system cross-linking agent (manufactured by Toyo Ink Co., Ltd., product name "Coronate L") was mixed in a solvent to obtain a pressure-sensitive 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.

[Test Example 1] (Measurement of shear force)
The surface of the base material of the pressure-sensitive adhesive sheet for stealth dicing obtained in Examples and Comparative Examples is lined with an instant adhesive (manufactured by Toagosei Co., Ltd., product name "Aron Alpha") on the surface opposite to the pressure-sensitive adhesive layer. A polyethylene terephthalate film (thickness: 100 μm) as a material was adhered to obtain a laminated body.

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 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) via an adhesive layer in an environment of a temperature of 23 ° C. and a relative humidity of 50%. At this time, a 2 kg roller was reciprocated once with respect to the sample to apply a load, and the sample was attached so that the 3 mm portion in the length direction was in close contact with 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 pieces of the unnecessary sample were peeled off from the silicon mirror wafer. As a result, as shown in FIGS. 1 and 2, a test object was obtained in which the sample and the silicon mirror wafer were attached in an area of 20 mm × 3 mm (60 mm ² ). In FIGS. 1 and 2, reference numeral 1 is a stealth dicing pressure-sensitive adhesive sheet (sample) 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. Is shown.

Twenty minutes after application, a tensile test was conducted using an autograph (manufactured by Imada Seisakusho Co., Ltd., product name "SDT-203NB-50R3") under the condition of a tensile speed of 1 mm / min in an environment of 23 ° C. , 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 substrate)
For the base materials used in Examples and Comparative Examples, the storage elastic modulus (MPa) of the base material at 23 ° C. was measured under the following equipment and conditions. The results are shown in Table 1.
Measuring device: Dynamic modulus measuring device "DMA Q800" manufactured by TA Instruments Co., Ltd.
Test start temperature: 0 ° C
Test end temperature: 200 ° C
Temperature rise 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 is applied to the peeling surface of the release sheet to form a pressure-sensitive adhesive layer, and the peel-off surface of the separately prepared release sheet is pressure-bonded to the exposed pressure-sensitive adhesive layer. , A pressure-sensitive adhesive sheet composed of a release sheet / adhesive layer / release sheet was produced. The release sheet was peeled off from the pressure-sensitive adhesive sheet, and a plurality of layers of the pressure-sensitive adhesive layer were laminated so as to have a thickness of 200 μm. A rectangle (thickness: 200 μm) of 30 mm × 4 mm was punched out from the obtained laminated body of the pressure-sensitive adhesive layer, and this was used as a measurement sample. For this measurement sample, the storage elastic modulus (kPa) of the pressure-sensitive adhesive layer at 23 ° C. was measured under the following equipment and conditions. The results are shown in Table 1.
Measuring device: Dynamic modulus measuring device "DMA Q800" manufactured by TA Instruments Co., Ltd.
Distance between measurements: 20 mm
Test start temperature: -30 ° C
Test end temperature: 120 ° C
Temperature rise rate: 3 ° C / min Frequency: 11Hz
Amplitude: 20 μm

[Test Example 4] (Evaluation of splittability)
A mirror surface of a 6-inch ring frame and a 6-inch silicon mirror wafer (thickness: 150 μm) was attached 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 is irradiated from the surface of the 6-inch silicon mirror wafer opposite to the adhesive sheet for stealth dicing under the following conditions. A modified layer was formed in the 6-inch silicon mirror wafer. The laser irradiation at this time was performed in two ways so that the sizes of the obtained chips were 8 mm square and 4 mm square, respectively.
<Irradiation conditions>
Irradiation height: 100 μm from the tape side
Frequency: 90Hz
Output: 0.25W
Processing speed: 360 mm / sec

Then, using an expanding device (manufactured by JCM, product name "ME-300B"), the work was expanded at a withdrawal speed of 100 mm / sec and a withdrawal amount of 10 mm in an environment of 23 ° C. Next, the number of chips that were well divided at the position of the modified layer and completely separated from the surrounding chips was measured, and the ratio (%) to the total number of theoretically obtained chips was calculated. Then, the fragmentability was evaluated based on the following criteria. The results are shown in Table 1.
◯: The above ratio is 100%.
Δ: The above ratio is less than 100% and 80% or more.
X: The above ratio is less than 80%.

As can be seen from Table 1, the adhesive sheet for stealth dicing obtained in the examples can satisfactorily divide the wafer on which the modified layer is formed by expanding, and in particular, the chip size is 8 mm square or the like. Even when it was as small as a 4 mm square, it showed excellent splittability.

The 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 at room temperature.

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

Claims (7)

At least, it is a stealth dicing pressure-sensitive adhesive sheet used for cutting and separating a semiconductor wafer having a modified layer formed therein into individual chips in a room temperature environment.
A base material and an adhesive layer laminated on one surface side of the base material are provided.
The base material is a single layer,
When the adhesive sheet for stealth dicing is attached to a silicon wafer via the adhesive layer, the shearing force at the interface between the adhesive layer and the silicon wafer at 23 ° C. is 70 N / (3 mm × 20 mm) or more. , 250 N / (3 mm × 20 mm) or less, an adhesive sheet for stealth dicing. The adhesive sheet for stealth dicing according to claim 1, wherein the chip has a minimum side length of 2 mm or more and 30 mm or less. The pressure-sensitive adhesive sheet for stealth dicing according to claim 1 or 2, wherein the semiconductor wafer has a thickness of 10 μm or more and 1000 μm or less. The pressure-sensitive adhesive sheet for stealth dicing according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer is composed of an energy ray-curable pressure-sensitive adhesive. The pressure-sensitive adhesive sheet for stealth dicing according to any one of claims 1 to 4, 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 5 to a semiconductor wafer.
A modified layer forming step of forming a modified layer inside the semiconductor wafer,
Manufacture of a semiconductor device including an expanding step of expanding the adhesive sheet for stealth dicing in a room temperature environment and cutting and separating the semiconductor wafer having a modified layer formed therein into individual chips. Method. The sixth aspect of the invention is characterized in that a laminating step of laminating an adhesive film is further provided on a surface of the semiconductor wafer bonded to the stealth dicing pressure-sensitive adhesive sheet on the side opposite to the stealth dicing pressure-sensitive adhesive sheet side. The method for manufacturing a semiconductor device according to the description.

Images