TWI791485B - 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, which is used at least on a semiconductor wafer that will form a modified layer inside, and is cut and separated into individual wafers at room temperature. The adhesive sheet 1 for invisible dicing has: base material 11; and an adhesive layer 12, which is laminated on one side of the above-mentioned base material 11, so that when the above-mentioned adhesive sheet 1 for stealth dicing is adhered to a silicon wafer through the adhesive layer 12, the adhesive layer 12 and the above-mentioned silicon wafer The shear force at the interface of the wafer at 23° C. is not less than 5 N/(3 mm×20 mm) and not more than 70 N/(3 mm×20 mm). This adhesive sheet 1 for stealth dicing is excellent in cleaning performance with respect to a wafer.

Description

Adhesive sheet for stealth dicing and method for manufacturing semiconductor device

This invention relates to the adhesive sheet for stealth dicing used for a stealth dicing (registered trademark) process, and the manufacturing method of the semiconductor device using this adhesive sheet for stealth dicing.

When manufacturing a wafer-shaped semiconductor device from a semiconductor wafer, conventionally, a blade dicing process in which a liquid for cleaning the semiconductor wafer is sprayed and the semiconductor wafer is cut with a rotary knife to obtain wafers is generally performed. However, in recent years, a stealth dicing process that can be divided into wafers by a dry method has begun to be used. An example of stealth dicing is to irradiate a semiconductor wafer attached to a dicing sheet with a large aperture (NA) laser to minimize damage near the surface of the semiconductor wafer and to form a modified layer inside the semiconductor wafer in advance. . Afterwards, by expanding the dicing sheet and applying force to the semiconductor wafer, it is cut and separated into individual wafers.

In recent years, it has been required to laminate the wafer produced as described above with another wafer, or to bond the wafer to a film substrate. Then, in some fields, there is a change from a face-up structure in which the circuit of a chip is connected to a circuit on another chip or a substrate by wire bonding, to a chip with protruding electrodes. The electrode forming surface of the electrode is opposite to the circuit on another chip or substrate, and the electrode is directly connected to the flip-chip structure, or through silicon via (Through Silicon Via; TSV). In response to the requirements for lamination and bonding of chips such as flip-chip structures, there is a proposal of a method of fixing a chip with electrodes to another chip or 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 manufacturing method, for a semiconductor wafer with an electrode or a modified semiconductor wafer with an electrode on which a dicing sheet is attached to the surface opposite to the electrode formation surface, A thin film-like adhesive is formed on the electrodes, and the wafer with electrodes divided by the expanding step is provided with an adhesive layer on the electrode-formed surface. For this adhesive layer, an adhesive film called a die attach film (Die Attach Film, DAF) or a nonconductive adhesive film (Nonconductive film, NCF) is used.

In Patent Document 1, it is disclosed that the DAF is bonded to the substrate, the stealth dicing process is performed, and then the wafer is divided into wafers by expanding, and the DAF can be divided.

[Prior Art Literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-19962

However, in the stealth dicing process described above, when the modified layer is cut and separated from the semiconductor wafer, fragments mainly originating from the modified layer may occur, and the fragments may adhere to the wafer. Therefore, wafer cleaning is performed to remove this debris.

Such wafer cleaning is sometimes performed on diced wafers. That is, after the semiconductor wafers are separated into wafers on the dicing sheet, the obtained wafers are cleaned while being stacked on the dicing sheet. At this time, by expanding the dicing sheet and increasing the interval between wafers (wafer interval), the wafer can be cleaned more favorably.

However, since the conventional dicing sheet using the method disclosed in Patent Document 1 cannot expand sufficiently, it is difficult to sufficiently widen the interval between wafers for good cleaning.

This invention was made in view of the above-mentioned actual situation, and aims at providing the adhesive sheet for stealth dicing excellent in the cleaning property of a wafer, and the manufacturing method of a semiconductor device.

In order to achieve the above goals, first, the present invention provides an adhesive sheet for stealth dicing, which is characterized in that: it is used at least on a semiconductor wafer that will form a modified layer inside, and is cut and separated into individual wafers at room temperature. An adhesive sheet for stealth dicing, comprising: a base material; and an adhesive layer laminated on one side of the base material, and when the adhesive sheet for stealth dicing is adhered to a silicon wafer via the adhesive layer, the above-mentioned The shear force at the interface between the adhesive layer and the silicon wafer at 23°C is 5N/(3mm×20mm) or more and 70N/(3mm×20mm) or less (Invention 1).

In the adhesive sheet for stealth dicing concerning the said invention (invention 1), by making the shear force of 23 degreeC into the said range, it can expand favorably in the state which laminated|stacked a wafer. Therefore, when cleaning the wafers, the interval between the wafers can be sufficiently widened, and as a result, the wafers can be cleaned well.

In the above invention (Invention 1), it is preferable that the adhesive layer is formed of an energy ray-curable adhesive (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the storage elastic modulus of the base material at 23° C. is not less than 10 MPa and not more than 600 MPa (Invention 3).

Second, the present invention provides a method of manufacturing a semiconductor device, which is characterized in that it includes: a bonding step of bonding the above-mentioned adhesive layer of the above-mentioned adhesive sheet for stealth dicing (Inventions 1 to 3) to a semiconductor wafer; A modified layer forming step of forming a modified layer inside the circle; an expanding step of expanding the above-mentioned adhesive sheet for stealth dicing at room temperature, and cutting and separating the above-mentioned semiconductor wafer formed with a modified layer inside into individual wafers; and Expanding the state of the above-mentioned adhesive sheet for stealth dicing and cleaning the above-mentioned wafer laminated on the above-mentioned adhesive sheet for stealth dicing (invention 4).

In the above invention (Invention 4), further comprising: a lamination step of laminating an adhesive film on the surface of the semiconductor wafer bonded to the adhesive sheet for stealth dicing that is opposite to the surface to which the adhesive sheet for stealth dicing is bonded. For better (invention 5).

According to the present invention, it is possible to provide an adhesive sheet for stealth dicing and a method of manufacturing a semiconductor device which are excellent in cleaning performance with respect to a wafer.

1‧‧‧Adhesive sheet for invisible cutting with backing material (sample)

11‧‧‧Substrate

12‧‧‧adhesive layer

13‧‧‧backing material

2‧‧‧Silicon mirror wafer

FIG. 1 is a plan view illustrating a method of measuring shear force related to Test Example 1. FIG.

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

Embodiments of the present invention will be described below.

[Adhesive sheet for stealth cutting]

The adhesive sheet for stealth dicing according to one embodiment of the present invention is used at least to cut and separate a semiconductor wafer in which a modified layer is formed into individual wafers at room temperature. Here, the room temperature environment means, for example, an environment of 5°C or higher, particularly preferably an environment of 10°C or higher, and more preferably an environment of 15°C or higher. In addition, the so-called room temperature environment means, for example, an environment below 45° C., an environment below 40° C. is particularly preferable, and an environment below 35° C. is more preferable. The above-mentioned temperature range can be easily achieved without intentional temperature management, so the cost of stealth dicing can be reduced. In addition, the "sheet" in this specification also includes the concept of "tape (type)".

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

When adhering the adhesive sheet for stealth dicing to a silicon wafer through the adhesive layer of the adhesive sheet for stealth dicing according to this embodiment, the shear force at the interface between the adhesive layer and the silicon wafer at 23°C is 5N/ (3mm×20mm) or more, 70N/(3mm×20mm) or less.

Regarding the adhesive sheet for stealth dicing of this embodiment, by having the shear force as described above, the semiconductor wafer with the reformed layer formed inside the adhesive sheet for stealth dicing can be cut at room temperature. After being separated into individual wafers, the interval between the wafers is sufficiently widened. Specifically, the distance between wafers (the distance between adjacent wafers) is increased to about 150 to 300 μm, preferably about 155 to 260 μm, and particularly preferably about 160 to 250 μm. By enlarging the distance between the wafers to such a distance, when cleaning the wafers, the cleaning liquid can easily enter between the wafers, and the chips generated by cutting and separating the semiconductor wafers can be effectively removed from the wafers. In addition, the measuring method of the said shear force is shown in the test example mentioned later.

If the above-mentioned shear force is less than 5N/(3mm×20mm), when a shear force is applied to the part where the adhesive sheet for stealth dicing is in close contact with the ring frame during expansion, the adhesive sheet for stealth dicing is more likely to fall off from the ring frame. Therefore, it cannot be used stably. On the other hand, if the shear force exceeds 70N/(3mm×20mm), the wafer gap cannot be sufficiently widened to a distance for good cleaning.

From the above point of view, the lower limit of the shear force is preferably 10N/(3mm×20mm) or more, particularly preferably 13N/(3mm×20mm) or more. In addition, the upper limit of the above-mentioned shearing force is preferably 65 N/(3 mm×20 mm) or less, particularly preferably 60 N/(3 mm×20 mm) or less.

Furthermore, with the adhesive sheet for stealth dicing of this embodiment, even after the expanded state is released, the interval between wafers can be maintained at an appropriate distance. Specifically, the wafer gap after release can be maintained at about 50 to 200 μm. By maintaining the distance between the wafers at such a distance, collision of the wafers after release can be suppressed.

1. Adhesive layer

The adhesive layer of the adhesive sheet for stealth dicing according to this embodiment is not particularly limited as long as it satisfies the above-mentioned shear force. 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 with desired adhesive force and re-peelability, for example, acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, Polyester-based adhesives, polyvinyl ether-based adhesives, etc. Among them, an acrylic adhesive that can effectively suppress peeling of semiconductor wafers, wafers, etc. in the modified layer forming step, the expanding step, and the like is preferable.

On the other hand, energy ray-curable adhesives can be hardened by energy ray irradiation to reduce the adhesive force. Therefore, when it is desired to separate the wafer obtained by dividing the semiconductor wafer from the adhesive sheet for stealth dicing, it can be irradiated with energy ray. , are easily separated.

The energy ray-curable adhesive constituting the adhesive layer may contain an energy ray-curable polymer as a main component, or may contain a non-energy ray-curable polymer (a polymer that does not have 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 an energy ray curable polymer and a non-energy ray curable polymer, or may be an energy ray curable polymer and a monomer having at least one energy ray curable group and A mixture of/or an oligomer, or a mixture of these three types may be used.

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

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

The acrylic copolymer (a1) preferably includes: 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 as a constituent unit of the acrylic copolymer (a1) contains a monomer, which is bonded with a polymerizable double bond 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. The monomer is better.

Hydroxyl-containing monomers, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate ester, 3-hydroxybutyl acrylate, 4-hydroxybutyl (meth)acrylate, and the like, and these may be used alone or in combination of two or more.

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 amino group-containing monomer or substituted amino 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.

As the (meth)acrylate monomer constituting the acrylic copolymer (a1), other than alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group, for example, those having A monomer of an alicyclic structure (an alicyclic structure contains a monomer).

Alkyl (meth)acrylates, especially alkyl (meth)acrylates with an alkyl group of 1 to 18 carbon atoms, can be used well. For example, methyl (meth)acrylate, ethyl (meth)acrylate 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.

The alicyclic structure contains monomers such as cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, (meth) ) dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

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

The acrylic copolymer (a1) is obtained by copolymerization of the above-mentioned functional group-containing monomers with (meth)acrylate monomers or their derivatives by conventional methods, except that between these monomers In addition, dimethyl acrylamide, vinyl formate, vinyl acetate, styrene, etc. can also be copolymerized.

An energy ray-curable polymer is obtained by reacting an 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 selected suitably according to the kind of the functional group of the functional group containing monomer unit which the acrylic-type 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 of the acrylic copolymer (a1) is an epoxy group, the unsaturated group contains the functional group of the compound (a2), preferably an amine group, a carboxyl group or an aziridine group.

In addition, in the above-mentioned unsaturated group-containing compound (a2), at least one energy ray polymerizable carbon-carbon double bond is contained in one molecule, preferably 1 to 6, and further preferably 1 to 4 good. Specific examples of such an unsaturated group-containing compound (a2) include, for example, 2-methacryloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryl Acryl isocyanate, allyl isocyanate, 1,1-(bisacryloxymethyl)ethyl isocyanate; diisocyanate compound or polyisocyanate compound, and acryl monomer Isocyanate compounds; diisocyanate compounds or polyisocyanate compounds, acryl monoisocyanate compounds obtained by reacting 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-containing compound (a2) is preferably used in a ratio of 50-95 mole % to the functional group-containing monomer of the above-mentioned acrylic copolymer (a1), and 60-93 mole % Particularly preferred, further preferably 70 to 90 mole %.

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 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) reacts with the functional group in the unsaturated group-containing compound (a2), and an 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 at least 10,000, particularly preferably 150,000 to 1.5 million, and further preferably 200,000 to 1 million. In addition, the weight average molecular weight (Mw) in this specification is the standard polystyrene conversion value measured by the gel permeation chromatography method (GPC method).

Even when the energy ray-curable adhesive is mainly composed of energy ray-curable polymers such as energy ray-curable polymer (A), the energy ray-curable adhesive may further contain energy ray-curable Monomers and/or oligomers (B).

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

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

For the energy ray-curable polymer (A), when the energy ray-curable monomer and/or oligomer (B) is formulated, the energy ray-curable monomer and/or oligomer (B) is hardened by the energy ray The content in the adhesive is preferably 0.1 to 180 parts by mass, particularly preferably 60 to 150 parts by mass, based on 100 parts by mass of the energy ray-curable polymer (A).

Here, when ultraviolet rays are used as energy rays for curing the energy ray-curable adhesive, it is preferable to add a photopolymerization initiator (C). 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-diethylthioxanthone, 1-hydroxycyclohexyl benzophenone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile , benzoyl (benzil), bibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzoyldiphenyl) 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 polymer (A) when compounding energy ray curable monomer and/or oligomer (B) The total amount of curable monomers and/or oligomers (B) (100 parts by mass) is 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 compounded in addition to the above-mentioned components. Other components include, for example, non-energy ray-curable polymer components or oligomer components (D), bridging agents (E), polymerizable branched polymers (F), and the like.

Non-energy ray curable polymer component or oligomer component (D), for example, polyacrylate, polyester, polyurethane, polycarbonate, polyolefin, high branched polymer, etc., weight average molecular weight (Mw) 30-2.5 million polymers or oligomers are preferred. By blending this component (D) into the energy ray curable adhesive, the adhesiveness and peelability before curing, the strength after curing, the easy peelability from the substrate, the adhesion with other layers, and the storage can be improved. stability etc. The compounding quantity of this component (D) is not specifically limited, It can determine suitably in the range of 0.01-50 mass parts with respect to 100 mass parts of energy ray hardening type copolymers (A).

As the bridging agent (E), a polyfunctional compound having reactivity with a functional group contained in 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, and metal chelate compounds. Compounds, metal salts, ammonium salts, reactive phenolic resins, etc. The above-mentioned shear force can be adjusted by compounding the bridge-linking agent (E) to 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 so-called 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 wafer laminated on the stealth dicing adhesive sheet can be reduced, and the process of transferring the semiconductor wafer from the stealth dicing adhesive sheet can be reduced. The mechanical load applied to semiconductor wafers during the step of picking them up individually with an 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) is likely to exist on the semiconductor wafer or the interface of the semiconductor wafer in the adhesive layer. Nearby tendency, or it may be that the polymerizable branched polymer (F) is irradiated with energy rays, and the energy ray hardening polymer (A) or the energy ray hardening monomer and/or oligomer (B) Aggregation, etc.

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

The weight-average molecular weight (Mw) of the polymerizable branched polymer (F) is determined by easily moderately suppressing the interaction of the energy ray-curable polymer (A) or the energy ray-curable monomer and/or oligomer (B). From the viewpoint of effect, it is preferably 1,000 or more, and particularly preferably 3,000 or more. In addition, the weight average molecular weight (Mw) is preferably at most 100,000, particularly preferably at most 30,000.

The content of the polymerizable branched polymer (F) in the adhesive layer is not particularly limited, but from the viewpoint of obtaining the above-mentioned effect by containing the polymerizable branched polymer (F) well, usually, with respect to energy ray curing Type polymer (A) 100 parts by mass, preferably at least 0.01 part by mass, more preferably at least 0.1 part by mass. 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 effect 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 the particles may lower the reliability of products having semiconductor wafers, it is preferable that the number of remaining particles is small. Specifically, the number of particles remaining on a silicon wafer, which is a semiconductor wafer, with a particle size of 0.20 μm or more is preferably less than 100, and particularly preferably 50 or less. From the viewpoint of easily satisfying such requirements for particles, the content of the polymerizable branched polymer (F) is preferably less than 3.0 parts by mass, preferably 2.5 parts by mass, relative to 100 parts by mass of the energy ray-curable polymer (A). It is particularly preferably not more than 2.0 parts by mass, and more preferably not more than 2.0 parts by mass.

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

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

As the monomer and/or oligomer having at least one energy ray-curable group, the same ones as those for 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, the monomer and/or oligomer having at least one energy ray-curable group The polymer is preferably 1 to 200 parts by mass, particularly preferably 60 to 160 parts by mass, based on 100 parts by mass of the non-energy ray-curable polymer component.

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

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

In the adhesive layer of the adhesive sheet for stealth dicing according to this embodiment, the storage elastic modulus at 23° C. is preferably 1 to 5000 kPa, particularly preferably 3 to 3000 kPa, and further preferably 5 to 2500 kPa. When the storage elastic modulus at 23° C. of the adhesive layer is in the above range, the adhesive sheet for stealth dicing becomes easy to spread, and the interval between wafers becomes easy to be effectively enlarged, and the wafer can be cleaned more favorably. In addition, the measuring method of the said storage elastic modulus is shown in the test example mentioned later.

2. Substrate

The base material of the adhesive sheet for stealth dicing according to this embodiment preferably has a storage elastic modulus at 23° C. of 10 MPa or more and 600 MPa or less. When the shear force of the adhesive layer is in the above-mentioned range, and the storage elastic modulus of the base material is in the above-mentioned range, then by these synergistic effects, the wafer interval of the wafer bonded to the adhesive sheet for stealth dicing can be sufficiently Extended, can effectively perform the cleaning effect of the wafer. In addition, the measuring method of the said storage elastic modulus is shown in the test example mentioned later.

In addition, if the above-mentioned storage modulus of elasticity is 10 MPa or more, since the base material exhibits a predetermined rigidity, the adhesive layer formed on the release sheet or the like can be laminated on the base material by transfer printing, and the stealth dicing can be efficiently produced. Adhesive sheet. Furthermore, the handleability of the adhesive sheet for stealth dicing becomes favorable. On the other hand, when the storage elastic modulus is 600 MPa or less, the adhesive sheet for stealth dicing can be stretched well by expansion. In addition, the semiconductor wafer can be well supported by the adhesive sheet for stealth dicing constructed on the ring frame.

From the above viewpoints, the lower limit value of the above-mentioned storage modulus of elasticity is preferably 50 MPa or more, particularly preferably 100 MPa or more. In addition, the upper limit of the storage elastic modulus is preferably not more than 580 MPa, particularly preferably not more than 550 MPa.

When the semiconductor wafer bonded to the adhesive sheet for stealth dicing is carried out through the adhesive sheet for stealth dicing and the modification layer forming step of irradiating laser light is performed, regarding the base material of the adhesive sheet for stealth dicing of this embodiment, the It is preferable that the 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 base material has light transmittance to the energy rays. The energy lines will be described later.

The base material of the adhesive sheet for stealth dicing according to this embodiment is preferably a film (resin film) mainly composed of a resin-based material, and is particularly preferably formed of only a resin film. Specific examples of resin films include ethylene-vinyl acetate copolymer films; ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)methyl acrylate copolymer films, other ethylene-(meth)acrylic acid Ethylene-based copolymer films such as ester copolymer films; polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene norbornene copolymer film, norbornene resin Polyolefin-based films such as films; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; polyethylene terephthalate films, polybutylene terephthalate films, polynaphthalene Polyester films such as ethylene glycol diformate; (meth)acrylate copolymer films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films, etc. Examples of polyethylene films include low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films. In addition, modified films such as these bridging films and ionomer films can also be used. The substrate may be a film formed of one of these materials, or a film formed by combining two or more of these materials. 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 kinds of materials are laminated. In this laminated film, the materials constituting each layer may be of the same kind or different kinds.

Among the above-mentioned films, polyolefin-based films such as ethylene-methacrylic acid copolymer films, polyethylene films, and polypropylene films, ionomer films of such polyolefins, polyvinyl chloride-based films, polyurethane films, or (a Base) acrylate copolymer film, film with linear low density polyethylene and polypropylene as material is preferred.

In the base material, various types of fillers, flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers, etc. may be contained in the above-mentioned film. additive. The content of these additives is not particularly limited, and it is preferable to maintain the range where the base material can exhibit the desired function.

In the adhesive sheet for stealth dicing of this embodiment, when the substrate and the adhesive layer are directly laminated, the surface of the substrate on the side of the adhesive layer may be treated with a primer 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 functions properly in the step of using the adhesive sheet for stealth dicing. The thickness is generally preferably 20-450 μm, particularly preferably 25-250 μm, and further preferably 50-150 μm.

3. Peeling sheet

A release sheet may be laminated on the surface of the adhesive sheet for stealth dicing of this embodiment opposite 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 film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, poly Ethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(formaldehyde base) acrylic copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. In addition, such bridging films can also be used. Furthermore, it may be a laminated film in which a plurality of these films are laminated.

The peeling surface (the peelable surface; especially the surface in contact with the adhesive layer) of the release sheet is preferably subjected to a peeling treatment. 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.

Furthermore, there is no particular limitation on the thickness of the release sheet, but it is usually about 20 μm to 100 μm.

4. Adhesion

Regarding the adhesive sheet for stealth dicing of this embodiment, the adhesive force to the silicon mirror wafer at 23° C. is preferably 1 N/25 mm or higher, particularly preferably 2 N/25 mm or higher. In addition, the adhesive force is preferably not more than 30N/25mm, and is particularly preferably not more than 29.5N/25mm. When the adhesive force at 23° C. is in the above range, when the adhesive sheet is expanded in the expanding step, it becomes easy to maintain the predetermined position of the semiconductor wafer and the obtained semiconductor wafer, and it becomes possible to smoothly perform separation in the modified layer portion of the semiconductor wafer. 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 means what is measured by the method mentioned later.

In the adhesive sheet for stealth dicing of this embodiment, when the adhesive layer is made of an energy ray-curable adhesive, the adhesive force to the silicon mirror wafer after irradiating energy rays at 23°C is preferably 10mN/25mm or more. Above 20mN/25mm is particularly good. In addition, the adhesive force is preferably not more than 1000mN/25mm, and is particularly preferably not more than 900mN/25mm. After the individualization of the semiconductor wafer is completed, the adhesive sheet for stealth dicing is irradiated with energy rays to reduce the adhesive force to the above-mentioned range, and the obtained semiconductor wafer can be easily picked up. In addition, adhesive force was measured by the method mentioned later.

The above-mentioned adhesive force at 23°C and the adhesive force after energy ray irradiation at 23°C can be measured as follows. First, cut the wafer for semiconductor processing into a width of 25 mm, and stick the surface on the side of the adhesive layer to the silicon mirror wafer. This bonding was carried out using a laminator (manufactured by Lintec Corporation, product name "RAD-3510F/12") under the conditions of a bonding speed of 10 mm/s, a protrusion amount of the substrate of 20 μm, and a roller pressure of 0.1 MPa. Next, the obtained laminated body of the semiconductor processing wafer and the silicon mirror wafer was left to stand in an atmosphere of 23° C. and 50% RH for 20 minutes. Here, when measuring the adhesive force after energy ray irradiation at 23°C, after standing for 20 minutes, the laminate was subjected to an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m/12") in a nitrogen atmosphere. Next, the sheet was irradiated with ultraviolet light (UV) (illuminance: 230 mW/cm ² , light intensity: 190 mJ/cm ² ) from the base material side. Leave it for 20 minutes or follow UV irradiation. According to JIS Z0237, use a universal tensile testing machine (manufactured by AMD, product name "RTG-1225"), with a peeling angle of 180° and a peeling speed of 300mm/min. The wafer was peeled off, and the measured value was taken as the adhesive force (mN/25mm).

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 the adhesive layer, and a coating composition further containing a solvent or a dispersant as desired, are prepared. Next, the coating composition is applied on the release surface of the release sheet by a die coater, curtain coater, spray coater, slit coater, knife coater, etc. Form a coating film. Furthermore, an adhesive layer is formed by drying this coating film. Afterwards, by bonding the adhesive layer on the release sheet to the base material, an adhesive sheet for stealth dicing is obtained. The properties of the coating composition are not particularly limited as long as it can be applied. The components for forming the adhesive layer may be contained in the coating composition as a solute or as a dispersoid.

When the coating composition contains a bridging agent (E), in order to form a bridging structure at a desired density, the above-mentioned drying conditions (temperature, time, etc.) may be changed, and heat treatment may be additionally provided. In order to fully carry out the bridging reaction, usually after the adhesive is laminated on the base material by the above method, the obtained adhesive sheet for stealth dicing is aged for several days in an environment of 23°C and 50% relative humidity.

Regarding the second example of the manufacturing method of the adhesive sheet for stealth dicing according to this embodiment, first, the above-mentioned coating composition is applied to one surface of the substrate to form a coating film. Next, this coating film is dried, and the laminated body which consists of a base material and an adhesive agent layer is formed. Furthermore, the surface of the laminate where the adhesive layer was exposed was bonded to the release surface of the release sheet. Thereby, the adhesive sheet for stealth dicing in which the release sheet was laminated|stacked on the adhesive layer can be obtained.

[Manufacturing method of semiconductor device]

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

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

According to the method of manufacturing a semiconductor device according to this embodiment, since the above-mentioned adhesive sheet for stealth dicing is used at least in the cleaning step, the gap between wafers can be sufficiently enlarged by spreading the adhesive sheet for stealth dicing. Therefore, the cleaning liquid can easily enter between the wafers, and the wafers can be cleaned well.

In addition, the method for manufacturing a semiconductor device according to the present embodiment may further include: on the surface of the semiconductor wafer bonded to the above-mentioned adhesive sheet for stealth dicing, which is opposite to the surface to which the above-mentioned adhesive sheet for stealth dicing is bonded, lamination and bonding Lamination step with films (DAF, NCF, etc.). According to the method of manufacturing a semiconductor device according to the present embodiment, it is possible to satisfactorily divide the bonding thin film through the expansion step.

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

(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 the semiconductor wafer is performed. Usually, the adhesive layer side surface 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 of the adhesive layer side of the adhesive sheet for stealth dicing, and to the region on the outer peripheral side of the region to which the semiconductor wafer is bonded. At this time, viewed from a top view, between the ring frame and the semiconductor wafer, there is an exposed area of the adhesive layer as a peripheral area.

(2) Lamination step

Next, you may perform the lamination process of laminating|stacking the adhesive film for a buildup with respect to the surface of the semiconductor wafer bonded to the adhesive sheet for stealth dicing which is opposite to the surface to which the said adhesive sheet for stealth dicing was bonded. This lamination is usually performed by heat lamination (thermal lamination). When an electrode is provided on the surface of the semiconductor wafer, usually, since the electrode exists on the surface of the semiconductor wafer opposite to the surface of the adhesive sheet for stealth dicing, a thin film is subsequently laminated on the electrode side of the semiconductor wafer.

Then use a film, DAF, NCF, etc. can be used, usually with thermal adhesiveness. The material is not particularly limited, and specific examples include a film-shaped member formed of a heat-resistant resin material such as polyimide resin, epoxy resin, or phenol resin, and an adhesive composition containing a curing accelerator.

(3) Modified layer formation step

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

(4) Expansion steps

After the modifying layer forming step, the cold spreading step of cutting and separating the semiconductor wafer is performed by spreading the adhesive sheet for stealth dicing at room temperature. Thereby, the semiconductor wafer obtained by dividing|segmenting a semiconductor wafer will be in the state adhered to the adhesive agent layer of the adhesive sheet for stealth dicing. In addition, 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 in the expanding step, and a wafer having an adhesive layer is obtained.

The specific conditions in the expansion step are not limited. For example, the temperature at the time of spreading the adhesive sheet for stealth dicing may be a general spreading temperature. As mentioned above, it is usually 5°C or higher, particularly preferably 10°C or higher, and more preferably 15°C or higher. In addition, the temperature is usually not higher than 45°C, particularly preferably not higher than 40°C, and more preferably not higher than 35°C.

(5) Cleaning steps

After the spreading step, a cleaning step of washing the wafer laminated on the stealth dicing adhesive sheet in the state where the adhesive sheet for stealth dicing is stretched is performed. In the washing step, the expansion can be carried out under normal conditions. For example, the expansion performed in the above-mentioned expansion step can be maintained in the washing step as it is, or after the above-mentioned expansion step, after the expansion is released, stealth cleavage can be performed again for the washing step. Expand with adhesive sheets. In addition, cleaning may be performed under normal conditions, for example, immersing the wafer in a cleaning solution for each adhesive sheet for stealth dicing. As described above, by performing the cleaning step using the adhesive sheet for stealth dicing according to this embodiment, the gap between the resulting wafers can be cleaned with a sufficiently widened gap, whereby debris adhering to the wafers can be favorably removed. Furthermore, the cleaning step may be performed after the shrinking step described below.

(6) Shrinkage step

When the peripheral region of the adhesive sheet for stealth dicing (the region between the ring frame and the wafer group is viewed from a plan view) relaxes in the expanding 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 base material located in the peripheral area shrinks, and the amount of slack generated by the adhesive sheet for stealth dicing due to the re-expanding step can be reduced. The heating method in the shrinking step is not limited. It can blow hot air, can also irradiate infrared rays, and can also irradiate microwaves.

(7) Pick up steps

When the shrinking step is performed following the washing step, after the shrinking step, when the washing step is performed following the shrinking step, or after the washing step when the shrinking step is not performed, individual wafers adhered to the adhesive sheet for stealth dicing are removed from the wafer for stealth dicing. Adhesive sheet pickup to obtain 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, the adhesive layer is irradiated with energy rays at any stage before the pick-up step after the bonding step to harden the adhesive layer, It is better to reduce the adhesion. Thereby, the pickup of the above-mentioned wafer can be performed more easily.

The energy line may include ionizing radiation, that is, X-rays, ultraviolet rays, electron rays, and the like. Among them, ultraviolet rays, which are relatively easy to introduce by irradiation equipment, are preferable.

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

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

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

The embodiments described above are described for easy understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above-mentioned embodiments includes all design changes or equivalents belonging to the technical scope of the present invention.

[Example]

Hereinafter, the present invention will be described in more detail using 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

Make the acrylic copolymer of butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=80/5/15 (mass ratio) reaction gained, and the 2-hydroxyethyl acrylate is 80 mol% Reaction of methacryloxyethyl isocyanate (MOI) to obtain an energy ray hardening polymer. The weight average molecular weight (Mw) of this energy ray curable polymer was 400,000.

100 parts by mass (value in terms of solid content; described in the same manner below) of the energy ray-curable polymer obtained, and 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, product name " Irgacure 184") 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 were mixed in a solvent to obtain an adhesive composition.

(2) Manufacture of adhesive sheets for stealth cutting

The adhesive composition described above was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET3811"). Next, it dried by heating, and made the coating film of the adhesive composition into an adhesive layer. The adhesive layer has a thickness of 10 μm. After that, by combining the adhesive layer on the obtained release sheet with a corona-treated ethylene-methacrylic acid copolymer (EMAA) film (thickness: 80 μm, surface tension of the corona-treated surface: 54mN/m) corona-treated surface to obtain an adhesive sheet for invisible cutting.

[Example 2]

Make the acrylic copolymer of 2-ethylhexyl acrylate/vinyl acetate/2-hydroxyethyl acrylate=60/20/20 (mass ratio) reaction gained, and the 2-hydroxyethyl acrylate is 80 moles % of methacryloxyethyl isocyanate (MOI) is reacted to obtain an energy ray hardening 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, 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 of 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 for using the obtained adhesive composition, an invisible Adhesive sheet for cutting.

[Example 3]

100 parts by mass of an acrylic copolymer (Mw: 600,000) obtained by reacting 2-ethylhexyl acrylate/methacrylate/acrylic acid=50/40/10 (mass ratio), 120 parts by mass as a 5-6 functional urethane acrylate (manufactured by Dainichi Seika Co., Ltd., product name "SEIKABEAM 14-29B"), 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (manufactured by BASF Corporation, product name "Irgacure 184"), and 0.286 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product The name "TETRAD C") is 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]

Linear low-density polyethylene resin (manufactured by Ube Maruzen Polyethylene Co., Ltd., product name "UMERIT 3540F") and polypropylene resin (manufactured by Idemitsu Petrochemical Co., Ltd., product name "F-724NP") were mixed with an extruder (Toyo Seiki Co., Ltd. Machinery Manufacturing Co., Ltd.) was extruded to produce a film with a thickness of 80 μm. An adhesive sheet for stealth dicing was produced in the same manner as in Example 2 except that one surface of the film was corona-treated.

[Example 5]

Make the acrylic copolymer of butyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=62/10/28 (mass ratio) reaction gained, and the 2-hydroxyethyl acrylate is 80 mol% Reaction of methacryloxyethyl isocyanate (MOI) to obtain 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 of 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 for using the obtained adhesive composition, an invisible Adhesive sheet for cutting.

[Comparative example 1]

The acrylic copolymer obtained by the reaction of lauryl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and 80 mol% of 2-hydroxyethyl acrylate Reaction of methacryloxyethyl isocyanate (MOI) to obtain 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 Corporation, product name "Irgacure184"), and 1.07 parts by mass of 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. In addition to using the obtained adhesive Except for the agent composition, it carried out similarly to Example 1, and produced the adhesive sheet for stealth dicing.

[Comparative example 2]

The acrylic copolymer obtained by the reaction of 2-ethylhexyl acrylate/methyl methacrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio), and the 2-hydroxyethyl acrylate is 80 Mole % of methacryloxyethyl 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 of 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 for using the obtained adhesive composition, an invisible Adhesive sheet for cutting.

[Comparative example 3]

2-ethylhexyl acrylate/isobornyl acrylate/2-hydroxyethyl acrylate=42/30/28 (mass ratio) reacted acrylic copolymer, and 80 moles of 2-hydroxyethyl acrylate % of methacryloxyethyl 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 of 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 for using the obtained adhesive composition, an invisible Adhesive sheet for cutting.

[Test Example 1] (Measurement of Shear Force)

On the surface of the base material of the adhesive sheet for stealth dicing obtained in Examples and Comparative Examples, which is on the side opposite to the adhesive layer, an instant adhesive (manufactured by Toagosei Co., Ltd., product name "Aron Alpha") was used as a backing A polyethylene terephthalate film (thickness: 100 μm) was followed to obtain a laminate.

The obtained laminate was cut into a length of 50 mm and a width of 30 mm in an environment of a temperature of 23° C. and a relative humidity of 50%, after which the release sheet was peeled off from the adhesive layer, and this was used as a sample. The sample was pasted on 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 2 kg roller was used to apply a load back and forth to the sample once, so that a portion of 3 mm in the longitudinal direction of the sample was closely adhered to the silicon mirror wafer. Next, on the silicon mirror wafer, only the sample is cut into a sample width of 20 mm with a dicing machine, and the unnecessary sample cut pieces are peeled off from the substrate. Thereby, as shown in FIG. 1 and FIG. 2 , a test object formed by pasting the sample and the silicon mirror wafer in an area of 20mm×3mm (60mm ² ) was obtained. Furthermore, in Figures 1 and 2, symbol 1 represents an adhesive sheet for stealth dicing with a backing material, symbol 2 is a silicon mirror wafer, symbol 11 is a base material, symbol 12 is an adhesive layer, and symbol 13 is a backing material.

After 20 minutes from pasting, perform a tensile test using a tensile compression tester (manufactured by Imada Seisakusho Co., Ltd., product name "SDT-203NB-50R3") at a tensile speed of 1mm/min in an environment of 23°C. , Determination of shear force (N/(3mm×20mm)). The results are shown in Table 1.

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

The storage elastic modulus (MPa) of the substrate at 23° C. was measured with the following apparatus and conditions for the substrates used in Examples and Comparative Examples. The results are shown in Table 1.

Measuring device: TA Instruments Co., Ltd., dynamic elastic modulus tester "DMA Q800"

Test start temperature: 0°C

Test end temperature: 200°C

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

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

The adhesive composition used in the examples and comparative examples was coated on the peeling surface of the release sheet to form an adhesive layer, and the peeling surface of the additionally prepared release sheet was pressed against the exposed adhesive layer to make a /Adhesive layer/Adhesive sheet formed by release sheet. The peeling sheet was peeled off from this adhesive sheet, and several layers were laminated|stacked so that the thickness of the adhesive layer might become 200 micrometers. The obtained laminated body of the adhesive layer was punched out in a rectangle (thickness: 200 μm) of 30 mm×4 mm, and this was used as a measurement sample. The storage elastic modulus (MPa) of the adhesive layer at 23 degreeC was measured for this measurement sample with the following apparatus and conditions. The results are shown in Table 1.

Measuring device: TA Instruments, dynamic mechanical analyzer "DMA Q800"

Distance between measurements: 20mm

Test start temperature: -30°C

Test end temperature: 120°C

Heating rate: 3°C/min

Frequency: 11Hz

Amplitude: 20μm

[Test Example 4] (Evaluation of Cleanability)

A 6-inch ring frame and a mirror surface of a 6-inch silicon mirror wafer (thickness: 100 μm) were bonded to the adhesive layer of the adhesive sheet for stealth dicing obtained in Examples and Comparative Examples. Next, using a stealth dicing device (manufactured by DISCO, product name "DFL7360"), under the following conditions, a laser is irradiated from the surface of the 6-inch silicon mirror wafer surface 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 resulting wafer would be 8 mm square.

<Irradiation conditions>

Irradiation height: 68μm from the tape surface

Frequency: 90Hz

Output: 0.3W

Processing speed: 360mm/sec

Thereafter, using an expanding device (manufactured by JCM, product name "ME-300B"), the above-mentioned workpiece was expanded at a pulling speed of 100 mm/sec and a pulling amount of 10 mm in an environment of 23°C. Immediately thereafter, the wafer spacing (μm) was measured with a digital microscope (manufactured by KEYENCE Corporation, product name "VHX-1000"), and an average value was calculated by measuring arbitrary 5 points. This average value was taken as the wafer gap (μm) immediately after expansion. In addition, the expandability was evaluated by the following reference|standard from the value of the wafer gap immediately after expansion. The results are shown in Table 1, respectively.

○: Wafer spacing is 150 μm or more

×: Interval between wafers is less than 150 μm

It can be seen from Table 1 that the adhesive sheet for stealth dicing obtained in the examples can sufficiently expand the wafer interval by spreading, and exhibit excellent cleaning properties.

【Industrial Profitability】

About the adhesive sheet for stealth dicing of this invention, it is applicable to the manufacturing method of the semiconductor device which performs the expansion process and a cleaning process.

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

2‧‧‧Silicon mirror wafer

Claims (5)

An adhesive sheet for stealth dicing, characterized in that: it is used at least on a semiconductor wafer that will form a modified layer inside, and the adhesive sheet for stealth dicing that is separated into individual wafers is cut and separated into individual wafers at room temperature, and it has: material; and an adhesive layer, which is laminated on one side of the above-mentioned substrate, the above-mentioned substrate is a single layer, and when the above-mentioned adhesive sheet for stealth dicing is pasted on the silicon wafer through the above-mentioned adhesive layer, the above-mentioned adhesive layer and The shear force at the interface of the above-mentioned silicon wafer at 23°C is above 5N/(3mm×20mm) and below 70N/(3mm×20mm). The adhesive sheet for stealth cutting as described in claim 1 of the patent application, wherein the above-mentioned adhesive layer is composed of an energy ray curable adhesive. The adhesive sheet for stealth dicing described in claim 1 of the patent application, wherein the storage elastic modulus of the base material at 23° C. is not less than 10 MPa and not more than 600 MPa. A method for manufacturing a semiconductor device, characterized in that: it is equipped with: a bonding step of bonding the above-mentioned adhesive layer of the adhesive sheet for stealth dicing described in any one of items 1 to 3 of the scope of application to a semiconductor wafer; A modified layer forming step of forming a modified layer inside the above-mentioned semiconductor wafer; expanding the above-mentioned adhesive sheet for stealth dicing at room temperature, and cutting and separating the above-mentioned semiconductor wafer with the modified layer formed inside into individual wafers. step; and a cleaning step of cleaning the wafer laminated on the above-mentioned adhesive sheet for stealth dicing in a state where the above-mentioned adhesive sheet for stealth dicing is expanded. The method for manufacturing a semiconductor device as described in item 4 of the patent scope, further In one step, a lamination step of laminating a subsequent film is provided on the surface of the semiconductor wafer bonded to the adhesive sheet for stealth dicing that is opposite to the surface to which the adhesive sheet for stealth dicing is bonded.

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