TWI762576B - Adhesive sheet for stealth dicing and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention is an adhesive sheet 1 for stealth dicing, characterized in that it is used at least in a semiconductor wafer having a modified layer formed therein, which is cut and separated into individual wafers in an environment of -20°C or higher and 10°C or lower. The adhesive sheet 1 for stealth dicing is provided with: a base material 11; When round, the shear force at 0° C. of the interface between the adhesive layer 12 and the silicon wafer is 190N/(3mm×20mm) or more and 400N/(3mm×20mm) or less. The adhesive sheet 1 for stealth dicing can satisfactorily separate semiconductor wafers into chips by cold expansion even if the size of the obtained chips is small.

Description

Adhesive sheet for stealth dicing and method for manufacturing semiconductor device

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

When manufacturing a wafer-shaped semiconductor device from a semiconductor wafer, conventionally, a blade dicing process in which a semiconductor wafer is cut with a rotary blade while spraying a liquid for cleaning the semiconductor wafer to obtain a wafer has been generally performed. However, in recent years, a stealth dicing process capable of dry dicing into wafers has been employed. As an example of stealth dicing, a semiconductor wafer attached to a dicing sheet is irradiated with a large aperture (NA) laser, and a modified layer is formed in advance in the semiconductor wafer while minimizing damage to the surface of the semiconductor wafer. . After that, by expanding the dicing blade, a force is applied to the semiconductor wafer, and the semiconductor wafer is cut and separated into individual wafers.

In recent years, it has been required to laminate the wafers produced as described above with other wafers, or to attach the wafers to a thin film substrate. Then, in some fields, there is a transition from a face-up type of packaging that connects circuits on a wafer with circuits on other wafers or substrates to a type of packaging that is provided with protruding electrodes. The electrode formation surface of the chip is opposite to the circuits on other chips or substrates, and is directly connected with the electrodes in a flip-chip package or through silicon via (TSV). In response to the requirements for lamination and bonding of wafers such as flip chip packaging, there has been a proposal for a method of fixing the wafer with electrodes to another wafer or thin film substrate using an adhesive.

Then, in order to be easily used in such applications, it is proposed that, in the process of the above-mentioned production method, a semiconductor wafer with electrodes or a modified semiconductor wafer with electrodes to which a dicing sheet is attached to the surface opposite to the electrode formation surface, is proposed. A thin-film adhesive is layered on the electrode formation area, and the electrode-attached wafer divided by the expansion step is provided with an adhesive layer on the electrode formation surface. For the adhesive layer, an adhesive film called a die attach film (DAF) or a non-conductive adhesive film (NCF) is used.

In Patent Document 1, it is disclosed that the DAF can be divided while adhering DAF to a substrate, performing stealth dicing, and then dividing the wafer into wafers by expanding.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-019962

The above-mentioned DAF, NCF, etc. have the characteristics of embrittlement in the low temperature region, so in order to improve the splitability of DAF, NCF, etc., the above-mentioned expansion is often carried out in a low temperature environment of about -20°C ~ 10°C is performed as a cold expansion step. .

In addition, in recent years, the miniaturization of products on which semiconductor devices are mounted and the advancement of MEMS (Micro Electro Mechanical System: Micro Electro Mechanical System) development have also reduced the required wafer size. However, the smaller the size of the wafer obtained by stealth dicing, the more likely it is that the semiconductor wafer cannot be cut and separated as expected, DAF, NCF, etc., or the resulting wafer with an adhesive layer during the cold expansion step. damage, etc.

The present invention has been accomplished in view of the above-mentioned actual conditions, and provides an adhesive sheet for stealth dicing and manufacture of a semiconductor device, which can satisfactorily separate semiconductor wafers into wafers by cold expansion even when the size of the obtained wafers is small. method as the goal.

In order to achieve the above-mentioned object, first, the present invention provides an adhesive sheet for stealth dicing, characterized in that it is used at least in a semiconductor wafer in which a modified layer is to be formed, in an environment of -20°C or higher and 10°C or lower. The adhesive sheet for stealth dicing, which is cut and separated into individual wafers, is provided with: a base material; In the case of a silicon wafer, the shear force at the interface between the adhesive layer and the silicon wafer at 0°C is 190N/(3mm×20mm) or more and 400N/(3mm×20mm) or less (Invention 1).

In the adhesive sheet for stealth dicing of the above invention (Invention 1), by setting the shear force at 0° C. within the above-mentioned range, during cold expansion, it is not easy to cause the adhesive sheet for stealth dicing to be laminated on the adhesive sheet for stealth dicing. The interface of the semiconductor wafer is shifted. As a result, the force that pulls the semiconductor wafer in the direction of the peripheral portion generated by the expansion of the adhesive sheet for stealth dicing is easily concentrated on the modified layer, and the semiconductor wafer can be favorably generated in the modified layer. segmentation. Therefore, even if the size of the obtained wafer is small, problems such as poor division and wafer breakage can be suppressed, and wafers that are satisfactorily individualized can be obtained.

In the above invention (Invention 1), the wafer preferably has a minimum side length of 0.5 mm or more and 20 mm or less (Invention 2).

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

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

In the above inventions (Inventions 1 to 4), the storage elastic modulus at 0°C of the substrate is preferably 100 MPa or more and 1500 MPa or less (Invention 5).

Second, the present invention provides a method of manufacturing a semiconductor device, comprising: a bonding step of bonding the adhesive layer of the adhesive sheet for stealth dicing (Inventions 1 to 5) to a semiconductor wafer; A modified layer forming step for forming a modified layer inside the circle; and in an environment of -20° C. or higher and 10° C. or lower, expanding the above-mentioned adhesive sheet for stealth dicing, and cutting and separating the above-mentioned semiconductor wafer with the modified layer formed inside. A cold expansion step for forming individual wafers (Invention 6).

The above invention (Invention 6) further includes: on the surface opposite to the surface on which the above-mentioned adhesive sheet for stealth dicing is adhered to the surface of the semiconductor wafer adhered to the above-mentioned adhesive sheet for stealth dicing, the step of laminating the film for lamination is as follows: Good (Invention 7).

According to the present invention, it is possible to provide an adhesive sheet for stealth dicing and a method for manufacturing a semiconductor device, which can satisfactorily separate semiconductor wafers into chips by cold expansion even when the size of the obtained wafer is small.

1‧‧‧Adhesive sheet for invisible dicing with backing material

11‧‧‧Substrate

12‧‧‧Adhesive layer

13‧‧‧Backing material

2‧‧‧Silicon Mirror Wafer

FIG. 1 is a plan view illustrating a method for measuring shear force in Test Example 1. FIG.

FIG. 2 is a cross-sectional view illustrating a method of measuring shear force in Test Example 1. FIG.

Hereinafter, embodiments of the present invention will be described.

[Adhesive sheet for invisible dicing]

The adhesive sheet for stealth dicing according to an embodiment of the present invention is used for at least cutting and separating a semiconductor wafer in which a modified layer is formed into individual wafers in a low temperature environment. Here, the low-temperature environment refers to a temperature environment where DAF, NCF, etc. are sufficiently brittle, for example, an environment of 10°C or lower, particularly preferably 6°C or lower, and more preferably 4°C or lower. In addition, the lower limit of the temperature of the low-temperature environment is not particularly limited. For example, the low-temperature environment refers to an environment of -20°C or higher, an environment of -15°C or higher is particularly preferable, and an environment of -10°C or higher is more preferable. environment is better. In an environment exceeding 10° C., embrittlement of DAF, NCF, etc. becomes insufficient, and there is a possibility that good segmentation cannot be performed. In addition, in an environment of less than -20°C, since DAF, NCF, or adhesive sheet is in an environment below the glass transition temperature (Tg) of these, there is a possibility that the adhesion to the semiconductor wafer may be lowered. There is a risk that the adhesive sheet will break during expansion. The step of forming the modified layer inside the semiconductor wafer (modified layer forming step) can be performed in a state where the semiconductor wafer is adhered to the adhesive sheet for stealth dicing, or the semiconductor wafer can be adhered to the adhesive sheet for stealth dicing performed before. In addition, "sheet" in this specification also includes the concept of "type".

The adhesive sheet for stealth dicing of this embodiment is equipped with: a base material; and the adhesive bond layer laminated|stacked on one surface of this base material. The substrate and the adhesive layer are preferably directly laminated, but not limited to this.

Through the adhesive layer of the adhesive sheet for stealth dicing of this embodiment, when the adhesive sheet for stealth dicing is attached to a silicon wafer, the shear force at the interface between the adhesive layer and the silicon wafer at 0°C is 190N/ (3mm×20mm) or more, preferably 195N/(3mm×20mm) or more, and particularly preferably 200N/(3mm×20mm) or more. Moreover, the said shear force is 400N/(3mm*20mm) or less, Preferably it is 300N/(3mm*20mm) or less, Especially preferably, it is 200N/(3mm*20mm) or less. When the above shear force is less than 190N/(3mm×20mm), the interface between the adhesive sheet for stealth dicing and the semiconductor wafer is likely to shift during cold expansion, especially when the wafer size is very small, the semiconductor cannot be cut and separated well wafer. On the other hand, when the above-mentioned shear force exceeds 400 N/(3 mm×20 mm), the wafer gap cannot be sufficiently widened by cold expansion. In addition, the measuring method of the said shearing force is as shown in the test example mentioned later.

Using the adhesive sheet for stealth dicing according to the present embodiment, when a semiconductor wafer with a modified layer formed therein is cut and separated into individual wafers in a low temperature environment, the minimum side length of the obtained wafer is preferably 0.5 mm to 20 mm. The length is particularly preferably 0.7 mm to 18 mm, and the length is further preferably 1.0 mm to 16 mm. With regard to the adhesive sheet for stealth dicing according to the present embodiment, as described above, the misalignment at the interface between the adhesive sheet for stealth dicing and the semiconductor wafer can be suppressed, and the semiconductor wafer can be cut and separated satisfactorily, so that the semiconductor wafer can be separated. The circles were well cut and separated to obtain small wafers of the wafer size as described above.

In addition, when using the adhesive sheet for stealth dicing according to the present embodiment, a semiconductor wafer with a modified layer formed therein is cut and separated into individual wafers in a low temperature environment, the thickness of the semiconductor wafer is preferably 10 μm to 1000 μm, and the thickness of the semiconductor wafer is preferably 10 μm to 1000 μm. The thickness is particularly preferably 20 μm to 950 μm, and the thickness is further preferably 30 μm to 900 μm. Generally speaking, the thicker the semiconductor wafer, the more difficult it is for the semiconductor to be expanded during cold expansion. The bulk wafer is well cut and separated into wafers. However, the adhesive sheet for stealth dicing of the present embodiment can suppress the misalignment at the interface between the adhesive sheet for stealth dicing and the semiconductor wafer as described above, and can satisfactorily cut and separate the semiconductor wafer. The relatively thick semiconductor wafer can also be cut and separated well.

1. Adhesive layer

The adhesive layer of the adhesive sheet for stealth dicing of the present embodiment is not particularly limited as long as the above-mentioned shear force is satisfied. The adhesive layer may be composed of a non-energy ray-curable adhesive or an energy ray-curable adhesive. Non-energy ray-curable adhesives are preferably those having desired adhesive force and releasability. For example, acrylic adhesives, rubber-based adhesives, silicone-based adhesives, urethane-based adhesives, Polyester-based adhesives, polyvinyl ether-based adhesives, etc. Among these, an acrylic adhesive which can effectively suppress the peeling off of semiconductor wafers, wafers, etc. in a modified layer formation step, a cold expansion step, and the like is preferable.

On the other hand, the energy ray-curable adhesive can be cured by energy ray irradiation and reduce the adhesive force. Therefore, when the wafer obtained by dividing the semiconductor wafer and the adhesive sheet for stealth dicing are to be separated, the energy ray irradiation can be used. , easily separated.

The energy-ray-curable adhesive constituting the adhesive layer can be composed mainly of a polymer having energy-ray-curability, or a non-energy-ray-curable polymer (polymer without energy-ray-curability) and at least A mixture of monomers and/or oligomers having one or more energy ray curable groups as a main component. In addition, it may be a mixture of a polymer with energy ray curability and a non-energy ray curable polymer, or a polymer with energy ray curability and A mixture of monomers and/or oligomers having at least one or more energy ray curable groups may be a mixture of these three types.

First, the case where the energy ray curable adhesive is mainly composed of a polymer having energy ray curability will be described below.

Energy-ray-curable polymer (meth)acrylate (co)polymer (A) (hereinafter, sometimes also referred to as energy-ray-curable functional group) introduced into the side chain It is preferably referred to as "energy ray-curable polymer (A)"). The energy ray-curable polymer (A) is reacted with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group as an acrylic copolymer (a1) having a functional group-containing monomer unit And get better. In addition, in this specification, (meth)acrylate means both an acrylate and a methacrylate. Other similar terms are also the same.

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

The functional group that is a structural unit of the acrylic copolymer (a1) contains a monomer, which is bonded with a double bond having polymerizable in the molecule, and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, an epoxy group, etc. monomer is better.

The hydroxyl group-containing monomers include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. ester, 3-hydroxybutyl acrylate, 4-hydroxybutyl (meth)acrylate, etc., these can be used individually or in combination of 2 or more types.

Carboxyl group-containing monomers include, for example, 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.

The amine group-containing monomer or the substituted amine group-containing monomer includes, for example, aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, and the like. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1) can be preferably used, for example, in addition to the (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms in the molecule. Monomer of alicyclic structure (alicyclic structure contains monomer).

Alkyl (meth)acrylate, especially alkyl (meth)acrylate having 1 to 18 carbon atoms in the alkyl group, for example, methyl (meth)acrylate and ethyl (meth)acrylate can be preferably used. ester, propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

Alicyclic structures contain monomers such as cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, (meth)acrylate ) Dicyclopentenyl acrylate, Dicyclopentenyloxyethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

The acrylic copolymer (a1) is a structural unit derived from the above-mentioned functional group-containing monomer, preferably 1 to 35% by mass, particularly preferably 5 to 30% by mass, and further preferably 10 to 25% by mass better. In addition, the acrylic copolymer (a1) is a structural unit derived from a (meth)acrylate monomer or a derivative thereof, and is preferably contained in a ratio of 50 to 99% by mass, particularly preferably 60 to 95% by mass , 70 to 90% by mass is particularly preferred.

Acrylic copolymer (a1) is obtained by copolymerizing the above-mentioned functional group-containing monomers with (meth)acrylate monomers or derivatives thereof by conventional methods, but in the case of any of these monomers. In addition, dimethylacrylamide, vinyl formate, vinyl acetate, styrene and the like may be copolymerized.

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

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

In addition, in the above-mentioned unsaturated group-containing compound (a2), the energy ray polymerizable carbon-carbon double bond is contained in one molecule at least one, preferably 1 to 6, and more preferably 1 to 4. good. Specific examples of such an unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacrylohydrin Allyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; diisocyanate compound or polyisocyanate compound, acrylyl monoacrylate obtained by reaction with hydroxyethyl (meth)acrylate Isocyanate compounds; diisocyanate compounds or polyisocyanate compounds, acrylyl monoisocyanate compounds obtained by reacting with polyol compounds and hydroxyethyl (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid , 2-(1-aziridine)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, etc.

The above-mentioned unsaturated group contains the compound (a2), and the functional group of the above-mentioned acrylic copolymer (a1) contains the molar number of monomers, which is preferably used in a ratio of 50 to 95 mol %, and is preferably used in a ratio of 60 to 93 mol %. Particularly preferred, and further preferably 70 to 90 mol %.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2) can be determined according to The combination of reaction temperature, pressure, solvent, time, presence or absence of catalyst, and the type of catalyst are appropriately selected. Thereby, the functional group present in the acrylic copolymer (a1) is reacted 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), An energy ray-curable polymer (A) was obtained.

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

The energy ray-curable adhesive may further contain an energy ray-curable Monomers and/or oligomers (B).

As the energy ray-curable monomer and/or oligomer (B), for example, esters of polyols and (meth)acrylic acid, etc. can be used.

Examples of the energy ray curable monomer and/or oligomer (B) include monofunctional acrylates such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and trimethylol. propane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate Polyfunctionality of acrylates, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, etc. Acrylates, polyester oligo(meth)acrylate, polyurethane oligo(meth)acrylate, etc.

When an energy-ray-curable monomer and/or oligomer (B) is prepared for the energy-ray-curable polymer (A), the energy-ray-curable monomer and/or oligomer (B) is The content of the 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 using ultraviolet rays as energy rays for curing the energy ray-curable adhesive, it is preferable to add a photopolymerization initiator (C), and by using this photopolymerization initiator (C), polymerization can be reduced Hardening time and light exposure.

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-hydroxycyclohexyl phenone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile , Benzyl (benzil), bibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]acetone, 2,2-dimethoxy -1,2-Diphenylethan-1-one. These may be used alone or in combination of two or more.

Photopolymerization initiator (C), energy-ray-curable copolymer (A) and energy-ray-curable copolymer (A) when energy-ray-curable monomer and/or oligomer (B) are prepared for energy-ray-curable polymer (A) The total amount of curable monomers and/or oligomers (B) is 100 parts by mass) 100 parts by mass, preferably used in an amount in the range of 0.1 to 10 parts by mass, particularly preferably 0.5 to 6 parts by mass.

In the energy ray-curable adhesive, other components may be appropriately blended in addition to the above-mentioned components. Other components include, for example, a non-energy ray curable polymer component or oligomer component (D), a bridging agent (E), a polymerizable branch polymer (F), and the like.

The non-energy ray-curable polymer component or oligomer component (D) includes, for example, polyacrylate, polyester, polyurethane, polycarbonate, polyolefin, hyperbranched polymer, etc., weight average molecular weight (Mw) A polymer or oligomer of 30 million to 2.5 million is preferred. By blending the component (D) in the energy ray-curable adhesive, the adhesiveness and peelability before curing, the strength after curing, the ease of peeling from the substrate, the adhesion with other layers, and the storage can be improved. stability, etc. Although the compounding quantity of this component (D) is not specifically limited, It can be suitably determined in the range of 0.01-50 mass parts with respect to 100 mass parts of energy-beam curable copolymers (A).

As the bridging agent (E), a polyfunctional compound having reactivity with a functional group possessed by 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 alkoxy compounds, and metal chelate compounds. Compounds, metal salts, ammonium salts, reactive phenol resins, etc. The above-mentioned shear force can be adjusted by preparing a bridging agent (E) for the energy ray-curable adhesive.

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

The polymerizable branched polymer (F) refers to a polymer having an energy ray polymerizable group and a branched structure. By making the energy ray-curable adhesive contain a polymerizable branched polymer, the transfer of organic substances from the adhesive layer to the semiconductor wafer or the semiconductor chip laminated on the adhesive sheet for stealth dicing can be suppressed, and at the same time, the transfer of the semiconductor chip from the invisible dicing adhesive sheet can be reduced. The mechanical load applied to the semiconductor wafer during the step of individually picking up the adhesive sheet for dicing. Although it is not clear how the polymerizable branched polymer (F) contributes to such an effect, it is considered that the polymerizable branched polymer (F) easily exists in the semiconductor wafer or the interface of the semiconductor wafer in the adhesive layer. There is a tendency that the polymerizable branched polymer (F) may be irradiated with energy rays, and the energy-ray-curable polymer (A) or the energy-ray-curable monomer and/or oligomer (B) effects of aggregation, etc.

Specific structures such as the molecular weight of the polymerizable branch polymer (F), the degree of branch structure, and the number of energy ray polymerizable groups contained in one molecule are not particularly limited. As an example of a method for obtaining such a polymerizable branched polymer (F), firstly, a monomer having two or more radically polymerizable double bonds in the molecule is combined with an active hydrogen group and an active hydrogen group in the molecule. A monomer having one radically polymerizable double bond and a monomer having one radically polymerizable double bond in the molecule are polymerized to obtain a polymer having a branched structure. Next, polymerization can be obtained by reacting the obtained polymer with a compound having 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 radical polymerizable double bond in the molecule. Sexually branched polymer (F). As a commercial item of the polymerizable branched polymer (F), for example, "OD-007" manufactured by Nissan Chemical Industry Co., Ltd. can be used.

The weight-average molecular weight (Mw) of the polymerizable branched polymer (F) is determined by the fact that the energy-ray-curable polymer (A) or the energy-ray-curable monomer and/or oligomer (B) can be easily and moderately inhibited from each other. From the viewpoint of action, 1,000 or more is preferable, and 3,000 or more is particularly preferable. In addition, the weight average molecular weight (Mw) is preferably 100,000 or less, particularly preferably 30,000 or less.

The content of the polymerizable branch polymer (F) in the adhesive layer is not particularly limited, but from the viewpoint of obtaining the above-mentioned effects by the inclusion of the polymerizable branch polymer (F), it is usually cured with respect to energy rays. 100 parts by mass of the type polymer (A), preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more. Since the polymerizable branched polymer (F) has a branched structure, even if it is contained in a relatively small amount in the adhesive layer, the above-mentioned effects can be obtained favorably.

Furthermore, depending on the type of the polymerizable branched polymer (F), the polymerizable branched polymer (F) may remain as particles on the semiconductor wafer or the contact surface between the semiconductor wafer and the adhesive layer. Since there is a possibility of lowering the reliability of a product having a semiconductor wafer, it is preferable that the number of particles remaining is small. Specifically, the number of particles having a particle size of 0.20 μm or more remaining on a silicon wafer serving as a semiconductor wafer is preferably less than 100, and particularly preferably 50 or less. The content of the polymerizable branched polymer (F) is preferably less than 3.0 parts by mass and preferably 2.5 parts by mass relative to 100 parts by mass of the energy ray-curable polymer (A) from the viewpoint of easily satisfying such requirements for particles. Parts by mass or less are particularly preferable, and more preferably 2.0 parts by mass or less.

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

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

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

In this case, the photopolymerization initiator (C), the bridging agent (E), and the like may be appropriately prepared in the same manner as described above.

The thickness of the adhesive layer is not particularly limited as long as it can function appropriately in each step of using the adhesive sheet for stealth dicing according to the present embodiment. Specifically, 1 to 50 μm is preferred, 3 to 40 μm is particularly preferred, and 5 to 30 μm is further preferred.

In the adhesive layer of the adhesive sheet for stealth dicing of the present embodiment, the storage elastic modulus at 0°C is preferably 0.02 to 40.0 MPa, particularly preferably 0.10 to 30.0 MPa, and more preferably 0.50 to 20.0 MPa. In addition, the measuring method of the said storage elastic modulus is shown in the test example mentioned later.

2. Substrate

Regarding the base material of the adhesive sheet for stealth dicing of the present embodiment, the storage elastic modulus at 0° C. is preferably 100 MPa or more and 1500 MPa or less. Generally, when the storage elastic modulus of the base material is too low, in the expansion step, the adhesive sheet for stealth dicing is more likely to be stretched preferentially in the area without the laminated semiconductor wafer than in the area with the laminated semiconductor wafer. However, by setting the storage elastic modulus in the above-mentioned range, the adhesive sheet for stealth dicing can be well stretched in the region where the laminated semiconductor wafer is formed, and as a result, the individual wafers can be cut and separated efficiently. In addition, the measurement method of the above-mentioned storage elastic modulus is as shown in the later-mentioned test example.

In addition, when the storage elastic modulus is 100 MPa or more, since the base material exhibits a predetermined rigidity, the adhesive layer formed on the release sheet or the like can be transferred by transfer and laminated on the base material, so that the stealth dicing can be efficiently produced. adhesive sheet. Moreover, the handleability of the adhesive sheet for stealth dicing also becomes favorable. On the other hand, when the said storage elastic modulus is 1500 MPa or less, the adhesive sheet for stealth dicing can be extended|stretched favorably by cold expansion. In addition, the semiconductor wafer can be favorably supported by the adhesive sheet for stealth dicing mounted on the ring frame.

From the above viewpoints, the lower limit of the storage elastic modulus is preferably 120 MPa or more, and particularly preferably 150 MPa or more. Further, the upper limit of the storage elastic modulus is preferably 1200 MPa or less, and particularly preferably 1000 MPa or less.

When the step of forming a modified layer irradiated with laser light is performed on the semiconductor wafer bonded to the adhesive sheet for stealth dicing through the adhesive sheet for stealth dicing, the base material of the adhesive sheet for stealth dicing of the present embodiment is used for It is preferable that light of the wavelength of the laser light exhibits excellent light transmittance.

In addition, when using energy rays to harden the adhesive layer, it is preferable that the substrate has light transmittance to the energy rays. The energy line will be described later.

The base material of the adhesive sheet for stealth dicing of the present embodiment is preferably a film (resin film) containing a resin-based material as a main material, and particularly preferably formed 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)acrylic acid copolymer film, other ethylene-(meth)acrylic acid Ethylene-based copolymer films such as ester copolymer films; polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, ethylene norbornene copolymer films, norbornene resins Polyolefin-based films such as films; polyvinyl chloride-based films such as polyvinyl chloride films, vinyl chloride copolymer films, etc.; polyethylene terephthalate films, polybutylene terephthalate films, polynaphthalene Polyester films such as ethylene dicarboxylate; (meth)acrylate copolymer films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films, etc. 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, modified films such as these bridge films and ionomer films can also be used. The base material may be a thin film formed of one of these, or a thin film formed of a combination of two or more of these. In addition, it may be a laminated film of a multilayer structure in which a plurality of layers formed of the above-mentioned one or more materials are laminated. In this laminated film, the material constituting each layer may be the same kind or different kinds.

Considering the use in the cold expansion step, the substrate, among the above-mentioned films, uses polyolefin-based films such as ethylene-methacrylic acid copolymer films, polyethylene films, polypropylene films, etc., and ionomer films of such polyolefins , polyvinyl chloride film, polyurethane film or (meth)acrylate copolymer film is preferred.

Various types of fillers, flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion trapping agents, etc. additive. The content of these additives is not particularly limited, and it is preferable to keep the content within the range in which the substrate can exhibit the desired function.

In the adhesive sheet for stealth dicing of the present embodiment, when the substrate and the adhesive layer are directly laminated, the surface of the substrate on the adhesive layer side may be subjected to primer treatment in order to improve the adhesiveness of the adhesive layer , corona treatment, plasma treatment and other surface treatment.

The thickness of the base material is not limited as long as it can function appropriately in the step of using the adhesive sheet for stealth dicing. The thickness is usually preferably 20 to 450 μm, particularly preferably 25 to 250 μm, and more preferably 50 to 150 μm.

3. Peel off sheet

A release sheet may be laminated on the surface of the adhesive sheet for stealth dicing according to the present embodiment on the opposite side to the base material side of the adhesive layer to protect the adhesive layer until the adhesive sheet for stealth dicing is used.

The release sheet is not particularly limited, and for example, polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, poly Ethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(methyl) base) acrylic copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Moreover, these bridge|bridging films can also be used. Furthermore, a laminated film in which a plurality of these films are laminated may be used.

It is preferable to give a peeling process to the peeling surface of the said peeling sheet (surface which has peelability; especially the surface which is in contact with the pressure-sensitive adhesive layer). The release agent used for the release treatment includes, for example, alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

In addition, although the thickness of a peeling sheet is not specifically limited, Usually, it is about 20 micrometers to 100 micrometers.

4. Adhesion

Regarding the adhesive sheet for stealth dicing of the present embodiment, the adhesive force to the silicon mirror wafer at 0° C. is preferably 0.5N/25mm or more, and particularly preferably 1.0N/25mm or more. In addition, the adhesive force is preferably 30N/25mm or less, and particularly preferably 25N/25mm or less. By setting the adhesive force at 0°C in the above range, it becomes easy to maintain the predetermined position of the semiconductor wafer or the obtained semiconductor wafer when the adhesive sheet is expanded in the cold expansion step, and the modified layer portion of the semiconductor wafer can be smoothly divided. . Furthermore, when the adhesive layer is composed of an energy ray-curable adhesive, the above-mentioned adhesive force refers to the adhesive force before energy ray irradiation. In addition, the adhesive force is measured by the method mentioned later.

Regarding the adhesive sheet for stealth dicing of the present embodiment, when the adhesive layer is composed of an energy ray-curable adhesive, the adhesive force to the silicon mirror wafer after irradiating energy rays at 23° C. is preferably 10 mN/25 mm or more. 20mN/25mm or more is particularly good. In addition, the adhesive force is preferably 1000mN/25mm or less, and particularly preferably 900mN/25mm or less. After the individualization of the semiconductor wafer is completed, by irradiating the adhesive sheet for stealth dicing with energy rays, the adhesive force is reduced to the above-mentioned range, and the obtained semiconductor wafer can be easily picked up. In addition, the adhesive force is measured by the method mentioned later.

The above-mentioned adhesive force at 0° C. and the adhesive force after irradiation with energy rays at 23° C. can be measured by the following methods. First, a semiconductor processing sheet is cut into a width of 25 mm, and the adhesive layer side surface is attached to a silicon mirror wafer. The bonding was performed using a laminator (manufactured by LINTEC, product name "RAD-3510F/12"), and the bonding speed was 10 mm/s, the substrate protrusion amount was 20 μm, and the roller pressure was 0.1 MPa. Next, the obtained laminate of the semiconductor processing sheet and the silicon mirror wafer was left to stand for 20 minutes in an atmosphere of 23° C. and 50% RH. Here, when measuring the adhesive force after irradiating energy rays at 23°C, after standing for 20 minutes, the laminate was subjected to a nitrogen atmosphere using an ultraviolet irradiation device (manufactured by LINTEC, product name "RAD-2000m/12"). Next, ultraviolet (UV) (illuminance 230 mW/cm ² , light intensity 190 mJ/cm ² ) was irradiated from the substrate side of the sheet. After standing for 20 minutes or then UV irradiation, according to JIS Z0237, using a universal tensile tester (manufactured by AMD, product name "RTG-1225"), at a peeling angle of 180° and a peeling speed of 300mm/min, the sheet was removed from the silicon mirror surface. The wafer was peeled off, and the measured value was taken as the adhesive force (mN/25mm). Here, when measuring the adhesive force at 0°C, the measurement using the above-mentioned universal tensile tester is performed in an environment of 0°C, and when measuring the adhesive force at 23°C, the measurement using the above-mentioned universal tensile testing machine is used. performed in an environment of 23°C.

5. Manufacturing method of adhesive sheet for stealth dicing

The manufacturing method of the adhesive sheet for stealth dicing of this embodiment is not specifically limited, A conventional method can be used. In the first example of this production method, first, an adhesive composition containing a material for an adhesive layer and a coating composition further containing a solvent or a dispersing agent as desired are prepared. Next, the coating composition is applied on the peeling surface of the peeling sheet by a die coater, a curtain coater, a spray coater, a slit coater, a knife coater, or the like A coating film is formed. Furthermore, an adhesive layer is formed by drying this coating film. Then, the adhesive sheet for stealth dicing is obtained by adhering the adhesive layer on the release sheet to the base material. The properties of the coating composition are not particularly limited as long as it can be applied. The component for forming the adhesive layer may be contained in the coating composition as a solute or as a dispersoid.

When the coating composition contains the bridging agent (E), in order to form a bridging structure with a desired density, the drying conditions (temperature, time, etc.) described above may be changed, and a heat treatment may be additionally provided. In order to fully advance the bridging reaction, usually after the adhesive layer is layered on the substrate by the above method, the obtained adhesive sheet for stealth dicing is subjected to aging, for example, in an environment of 23° C. and a relative humidity of 50% for several days.

About the 2nd example of the manufacturing method of the adhesive sheet for stealth dicing of this embodiment, first, the said composition for coating layers is apply|coated to one surface of a base material, and a coating film is formed. Next, the coating film is dried to form a layered body composed of the base material and the adhesive layer. Furthermore, the surface which exposed the adhesive bond layer of this laminated body was adhere|attached to the peeling surface of a peeling sheet. Thereby, the adhesive sheet for stealth dicing in which the peeling sheet was laminated on the adhesive layer was obtained.

[Manufacturing method of semiconductor device]

A method of manufacturing a semiconductor device according to an embodiment of the present invention includes: a bonding step of bonding the adhesive layer of the above-mentioned adhesive sheet for stealth dicing (about the adhesive sheet for stealth dicing of the present embodiment) to a semiconductor wafer; The modified layer forming step of forming the modified layer inside the wafer; the cold expansion step of expanding the adhesive sheet for stealth dicing in a low temperature environment, so that the semiconductor wafer with the modified layer formed inside is cut and separated into individual wafers.

In the above manufacturing method, the bonding step may be performed before the modification layer formation step, or conversely, the modification layer formation step may be performed prior to the bonding step. In the modified layer forming step performed in the former procedure, the semiconductor wafer adhered to the adhesive sheet for stealth dicing according to the present embodiment is irradiated with laser light. In the step of forming the modified layer performed in the latter order, for example, a semiconductor wafer bonded to another adhesive sheet (eg, a post-grinding sheet) is irradiated with laser light.

According to the manufacturing method of the semiconductor device of the present embodiment, since the above-mentioned adhesive sheet for stealth dicing is used at least in the cold expansion step, it becomes difficult for the adhesive sheet for stealth dicing and the semiconductor wafer interface to shift in the cold expansion step. As a result, the force that pulls the semiconductor wafer in the direction of the peripheral portion due to the expansion of the adhesive sheet for stealth dicing is easily concentrated on the modified layer, and the semiconductor wafer can be favorably divided in the modified layer. . Therefore, even if the size of the obtained wafer is small, problems such as defective division and wafer breakage can be suppressed, and individual wafers can be obtained favorably.

In addition, the method for manufacturing a semiconductor device according to the present embodiment may further include laminating a film ( DAF, NCF, etc.) lamination step. According to the manufacturing method of the semiconductor device of the present embodiment, since the cold expansion step is performed, the thin film for adhesive can be satisfactorily divided in a low temperature environment.

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 step

First, a bonding step of bonding the adhesive layer of the adhesive sheet for stealth dicing according to the present embodiment to a semiconductor wafer is performed. Usually, the surface on the adhesive layer side of the adhesive sheet for stealth dicing is adhered to one surface of the semiconductor wafer, but it is not limited to this. In this bonding step, usually, the ring frame is bonded to the surface on the adhesive layer side of the adhesive sheet for stealth dicing, and the region on the outer peripheral side of the region where the semiconductor wafer is bonded. At this time, when viewed from a top view, between the ring frame and the semiconductor wafer, there is a region where the adhesive layer is exposed as a peripheral region.

(2) Lamination step

Next, you may perform the lamination process of the film for lamination|stacking with respect to the surface on the opposite side of the semiconductor wafer adhered to the adhesive sheet for stealth dicing and the surface adhering to the said adhesive sheet for stealth dicing. This lamination is usually performed by heating lamination (thermal lamination). When an electrode is provided on the surface of a semiconductor wafer, generally, since the electrode is present on the surface of the semiconductor wafer on the opposite side to the surface of the adhesive sheet for stealth dicing, a thin film is subsequently laminated on the electrode side of the semiconductor wafer.

The film for subsequent use may be DAF, NCF, or the like, and generally has thermal adhesiveness. The material is not particularly limited, and specific examples thereof include a film-like member formed of a heat-resistant resin material such as polyimide resin, epoxy resin, and phenol resin, and an adhesive composition containing a curing accelerator.

(3) Step of forming the modified layer

The modification layer forming step of forming the modification layer inside the semiconductor wafer is preferably carried out after the above-mentioned bonding step or after the lamination step, but the modification layer forming step may also be carried out before these steps. In the step of forming the modified layer, generally, a focal point set inside the semiconductor wafer is irradiated with a laser beam in the infrared region (stealth dicing). The irradiation of laser light can be performed on either side of the semiconductor wafer. The step of forming the modified layer is performed after the step of lamination, and it is preferable to irradiate laser light through the adhesive sheet for stealth dicing. In addition, when the step of forming the modified layer is performed between the above-mentioned bonding step and the above-mentioned laminating step, or when the above-mentioned laminating step is not performed, the semiconductor wafer is directly irradiated with laser light without passing through the adhesive sheet for stealth dicing. good.

(4) Cold expansion step

After the step of forming the modified layer, by expanding the adhesive sheet for stealth dicing in a low temperature environment, a cold expanding step of cutting and separating the semiconductor wafer is performed. Thereby, the semiconductor wafer obtained by dividing the semiconductor wafer is in a state of being adhered to the adhesive layer of the adhesive sheet for stealth dicing. In addition, when the film for adhesive is laminated on a semiconductor wafer, the film for adhesive is also divided at the same time as the semiconductor wafer is divided by the expansion step, and a wafer having an adhesive layer is obtained.

Specific conditions in the cold expansion step are not limited. For example, the temperature at the time of spreading the adhesive sheet for stealth dicing may be a general cold spreading temperature, and as described above, it is usually 10°C or lower, particularly preferably 6°C or lower, and more preferably 4°C or lower. Further, the lower limit of the temperature for cold expansion is not particularly limited, but is usually -20°C or higher, particularly preferably -15°C or higher, and more preferably -10°C or higher. As described above, by performing the cold expansion step using the adhesive sheet for stealth dicing according to the present embodiment, the semiconductor wafer can be well cut and separated into wafers, and when there is a laminate adhesive film, the adhesive can also be well divided. film.

(5) Re-expansion step

After the cold expansion step, the adhesive sheet for stealth dicing and the semiconductor wafer laminated thereon or the wafer with the adhesive layer can be returned to the room temperature environment, and the expansion step (re-expansion step) can be performed again in the room temperature environment. Specific conditions in the re-expansion step are not particularly limited except that the expansion is performed at room temperature (eg, 23° C.).

Furthermore, by this re-expanding step, usually, slack occurs in the peripheral region of the adhesive sheet for stealth dicing (the region between the ring frame and the wafer group when viewed from above).

(6) Shrinking step

When the peripheral region of the adhesive sheet for stealth dicing is loosened by the re-expansion step, it is preferable to perform the shrinking step of heating the peripheral region. By heating the peripheral area of the adhesive sheet for stealth dicing, the substrate located in the peripheral area shrinks, and the amount of relaxation of the adhesive sheet for stealth dicing due to the re-expansion step can be reduced. The heating method in the shrinking step is not limited. Hot air can be blown, infrared rays can also be irradiated, and microwaves can also be irradiated.

(7) Picking step

When the re-expansion step is performed, immediately after the shrinking step, when the re-expansion step is not performed, after the cold expansion step, the wafers attached to the adhesive sheet for stealth dicing are individually picked up from the adhesive sheet for stealth dicing, A pick-up step for obtaining a wafer as a semiconductor device.

Here, when the adhesive layer of the adhesive sheet for stealth dicing is formed of an energy ray-curable adhesive, after the bonding step, at any stage before the pick-up step, the adhesive layer is irradiated with energy rays to harden the adhesive layer. It is better to reduce the adhesion. Thereby, the pick-up of the said wafer can be performed more easily.

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

When ultraviolet rays are used for the ionizing radiation, it is easy to handle, and near ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm may be used. The amount of ultraviolet light can be appropriately selected according to the type of the energy ray-curable adhesive contained in the adhesive layer and the thickness of the adhesive layer, usually about 50~500mJ/ ^cm2 , preferably 100~450mJ/ ^cm2 , 150~400mJ/cm ² is better. In addition, the ultraviolet illuminance is usually about 50~500mW/ ^cm2 , preferably 100~450mW/ ^cm2 , more preferably 150~400mW/ ^cm2 . The ultraviolet light source is not particularly limited, and for example, a high pressure mercury lamp, a halogen lamp, and a light emitting diode (LED) can be used.

When electron beams are used for the ionizing radiation, the accelerating voltage can be appropriately selected according to the energy ray polymerizable group contained in the adhesive layer, the type of the energy ray polymerizable compound, and the thickness of the adhesive layer. ~1000kV is better. In addition, the irradiation dose may be appropriately selected according to the type of the energy ray-curable adhesive contained in the adhesive layer and the thickness of the adhesive layer, and is usually selected in the range of 10 to 1000 krad. The electron beam source is not particularly limited, and for example, a Cockcroft-Walton type, a van de graaff type, a resonance transformer type, an insulated core transformer type, or a linear Various electron ray accelerators such as Dynamitron type, Dynamitron type, and high-frequency wave type.

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

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

[Example]

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

[Example 1]

(1) Preparation of adhesive composition

Acrylic copolymer obtained by reacting lauryl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and the acrylic acid The 2-hydroxyethyl ester was reacted with 80 mol% methacryloyloxyethyl isocyanate (MOI) to obtain an energy ray hardening type polymer (Mw: 400,000).

100 parts by mass (solid content conversion value; the same description below) of the obtained energy ray-curable polymer and 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, product name " Irgacure 184") and 1.07 parts by mass of a toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") as a bridging agent were mixed in a solvent to obtain an adhesive composition.

(2) Manufacture of adhesive sheet for stealth dicing

The said adhesive composition was apply|coated to the peeling surface of the peeling sheet (made by LINTEC, product name "SP-PET3811"). Next, it is dried by heating, and the coating film of the adhesive composition is used as an adhesive layer. The thickness of this adhesive layer was 10 μm. Then, by combining the adhesive layer on the obtained release sheet with a corona-treated ethylene-methacrylic acid copolymer (EMAA) film (thickness: 80 μm) as a base material on one side, the surface tension of the corona-treated surface was : 54 mN/m) corona-treated surface was bonded to obtain an adhesive sheet for stealth dicing.

[Example 2] An acrylic copolymer obtained by reacting 2-ethylhexyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and the acrylic acid 2- The hydroxyethyl ester was reacted with 80 mol% methacryloyloxyethyl isocyanate (MOI) to obtain an energy ray hardening type polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 1.07 parts by mass as a bridging agent toluene diisocyanate An ester-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Example 3]

Acrylic copolymer obtained by reacting butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and the 2-hydroxyethyl acrylate in an amount of 80 mol% 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, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 1.07 parts by mass as a bridging agent A toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Example 4]

Acrylic copolymer obtained by reacting butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and 70 mol% of 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, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 0.43 parts by mass as a bridging agent A toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. In addition to using the resulting adhesive combination Other than that, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 1]

The acrylic copolymer obtained by the reaction of butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=80/5/15 (mass ratio), and the methyl acrylate of 80 mol% of the 2-hydroxyethyl acrylate Acryloyloxyethyl isocyanate (MOI) was reacted to obtain an energy ray-curable polymer (Mw: 400,000).

100 parts by mass (solid content conversion value; the same description below) of the obtained energy ray-curable polymer and 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, product name "Irgacure 184") as a photopolymerization initiator were prepared. ”) and 0.49 parts by mass of a toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name “CORONATE L”) as a bridging agent in a solvent, to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 2]

The acrylic copolymer obtained by reacting 2-ethylhexyl acrylate/vinyl acetate/2-hydroxyethyl acrylate = 60/20/20 (mass ratio) is 80 moles with the 2-hydroxyethyl acrylate % of methacryloyloxyethyl isocyanate (MOI) was reacted to obtain an energy ray hardening type polymer (Mw: 400,000).

100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 0.31 parts by mass as a bridging agent The toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 3]

The acrylic copolymer obtained by the reaction of butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=62/10/28 (mass ratio), and the methyl acrylate of 80 mol% of the 2-hydroxyethyl acrylate Acryloyloxyethyl 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, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 1.61 parts by mass as a bridging agent. A toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative Example 4]

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

100 parts by mass of the obtained energy ray-curable polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, and 1.07 parts by mass as a bridging agent A toluene diisocyanate-based bridging agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") was mixed in a solvent to obtain an adhesive composition. Except having used the obtained adhesive composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Test Example 1] (Measurement of Shear Force)

The difference between the base materials of the adhesive sheets for stealth dicing obtained in Examples and Comparative Examples The adhesive layer was on the opposite side, and a polyethylene terephthalate film (thickness: 100 μm) as a backing material was adhered using an instant adhesive (manufactured by Toagosei Co., Ltd., product name “Aron Alpha”), A laminate is obtained.

The obtained laminate was cut into a length of 50 mm and a width of 30 mm in an environment with a temperature of 23° C. and a relative humidity of 50%, and then the release sheet was peeled off from the adhesive layer to obtain a sample. The sample was attached to the mirror surface of a silicon mirror wafer (thickness: 350 μm) via an adhesive layer in an environment with a temperature of 23° C. and a relative humidity of 50%. At this time, a load of 2 kg was applied back and forth to the sample, and a portion of 3 mm in the longitudinal direction of the sample was closely attached to the silicon wafer. Next, on the silicon mirror wafer, only the sample was cut with a dicing machine so that the sample width was 20 mm, and the unnecessary sample cut pieces were peeled off from the substrate. As a result, as shown in FIGS. 1 and 2 , a test object in which the sample and the silicon mirror wafer were bonded together in an area of 20 mm×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, reference numeral 2 denotes a silicon mirror wafer, reference numeral 11 denotes a substrate, reference numeral 12 denotes an adhesive layer, and reference numeral 13 denotes an adhesive layer. It is a backing material.

Immediately after the above-mentioned pasting, the obtained test object was moved to an environment of 0°C, and 20 minutes after the pasting was carried out in a 0°C environment at a tensile speed of 1 mm/min using a tensile compression tester (manufactured by Imada Manufacturing Co., Ltd. , product name "SDT-203NB-50R3") to conduct tensile test and measure shear force (N/(3mm×20mm)). The results are shown in Table 1.

[Test Example 2] (Measurement of Storage Elastic Modulus of Base Material)

For the substrates used in the Examples and Comparative Examples, the storage elastic modulus (MPa) of the substrates at 0° C. was measured with the following apparatus and conditions. The results are shown in Table 1.

Measuring device: Dynamic elastic modulus analyzer "DMA Q800" manufactured by TA Instruments

Test start temperature: 0℃

Test end temperature: 200℃

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

[Test Example 3] (Measurement of Storage Elastic Modulus of Adhesive Layer)

The adhesive composition used in the Examples and Comparative Examples was applied to the release surface of the release sheet to form an adhesive layer, and the release surface of the release sheet prepared separately was laminated to the exposed adhesive to produce a release sheet composed of /Adhesive layer/The adhesive sheet formed by the peeling sheet. The release sheet was peeled off from the adhesive sheet, and a plurality of layers were laminated so that the thickness of the adhesive layer was 200 μm. The obtained laminated body of the adhesive layer was punched out in a rectangle of 30 mm×4 mm (thickness: 200 μm), and this was used as a measurement sample. For this measurement sample, the storage elastic modulus (MPa) of the adhesive layer at 0° C. was measured by the following apparatus and conditions. The results are shown in Table 1.

Measuring device: Elastic modulus measuring device "ARES" manufactured by TA Instruments

Distance between measurements: 20mm

Test start temperature: -30℃

Test end temperature: 120℃

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

[Test example 4] (evaluation of scalability)

On the adhesive layer of the adhesive sheets for stealth dicing obtained in Examples and Comparative Examples, a 6-inch ring frame and a mirror surface of a 6-inch silicon mirror wafer (thickness: 150 μm) were pasted. Next, using a stealth dicing device (manufactured by DISCO, product name "DFL7360"), under the following conditions, the surface of the 6-inch silicon mirror wafer surface was irradiated with a laser from the side opposite to the adhesive sheet for stealth dicing, A modified layer is formed in the silicon mirror wafer. The laser irradiation method at this time was performed so that the size of the obtained wafer was 16 mm square, 8 mm square, 4 mm square, and 1 mm square, respectively.

<Irradiation Conditions>

Irradiation height: 100μm from the tape surface

Frequency: 90Hz

Output: 0.25W

Processing speed: 360mm/sec

Then, using an expansion device (manufactured by JCM Corporation, product name "ME-300B"), the above-mentioned workpiece was expanded at a pull-down speed of 100 mm/sec and a pull-down amount of 10 mm in an environment of 0°C. Next, the number of wafers that were well disconnected at the position of the modified layer and completely separated from the surrounding wafers was counted, and the ratio (%) to the total number of theoretically available wafers was calculated. Then, the splitability is evaluated with the following benchmarks. The results are shown in Table 1.

○: The above ratio is 100%.

△: The above ratio is less than 100% and 80% or more.

×: The above ratio is less than 80%.

It can be seen from Table 1 that the adhesive sheets for stealth dicing obtained in the examples can be well separated from the wafers on which the modified layers are formed by cold expansion, especially even when the size of the wafers is as small as 4 mm square or 1 mm square. Shows excellent splitability.

【Industrial Profitability】

The adhesive sheet for stealth dicing of the present invention can be applied to a method of manufacturing a semiconductor device that performs cold expansion.

1‧‧‧Adhesive sheet for invisible dicing with backing material

2‧‧‧Silicon Mirror Wafer

Claims (7)

An adhesive sheet for stealth dicing, characterized in that it is used at least for cutting and separating a semiconductor wafer with a modified layer inside it into individual wafers in an environment of -20°C or higher and 10°C or lower. A sheet comprising: a base material; and an adhesive layer, which is laminated on one surface of the base material, and when the above-mentioned adhesive sheet for stealth dicing is adhered to a silicon wafer via the above-mentioned adhesive layer, the above-mentioned adhesive layer and the above-mentioned The shear force at the interface of the silicon wafer at 0°C is 190N/(3mm×20mm) or more and 300N/(3mm×20mm) or less, and the surface of the above-mentioned adhesive layer opposite to the above-mentioned base material is opposite to the semiconductor wafer. Attach directly. The adhesive sheet for stealth dicing according to claim 1, wherein the wafer has a minimum side length of 0.5 mm or more and 20 mm or less. The adhesive sheet for stealth dicing according to claim 1, wherein the thickness of the semiconductor wafer is 10 μm or more and 1000 μm or less. The pressure-sensitive adhesive sheet for stealth dicing according to claim 1, wherein the pressure-sensitive adhesive layer is formed of an energy-beam-curable pressure-sensitive adhesive. The adhesive sheet for stealth dicing according to claim 1, wherein the base material is a single layer. A method of manufacturing a semiconductor device, comprising: a bonding step of bonding the above-mentioned adhesive layer of the adhesive sheet for stealth dicing as described in any one of items 1 to 5 of the scope of application to a semiconductor wafer; The modified layer forming step of forming the modified layer inside the above-mentioned semiconductor wafer; and A cold expansion step in which the above-mentioned adhesive sheet for stealth dicing is expanded in an environment above -20°C and below 10°C, and the above-mentioned semiconductor wafer with a modified layer formed inside is cut and separated into individual wafers. The method for manufacturing a semiconductor device according to claim 6, further comprising: a surface on the opposite side of the semiconductor wafer bonded to the adhesive sheet for stealth dicing from the surface on which the adhesive sheet for stealth dicing is bonded, Lamination is followed by a lamination step with films.

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