JP6839925B2 - Semiconductor processing sheet - Google Patents

Description

The present invention relates to a semiconductor processing sheet, and more particularly to a semiconductor processing sheet preferably used for processing a semiconductor wafer or a semiconductor chip having protrusions.

In recent years, not only semiconductor chips having a two-dimensional pattern in which a circuit has been formed, but also semiconductor chips having protrusions as a three-dimensional structure have come to be seen. For example, in recent years, in the manufacture of semiconductor devices, a technique called wireless bonding is used when a chip individualized by dicing is placed on a substrate. In this method, the chip and the substrate are electrically connected without using a thin metal wire. As an example, a protruding electrode called a bump provided on the chip is brought into contact with an electrode on the substrate. By doing so, an electrical connection is secured. In addition, the protrusion may be used as a spacer.

In an example of a method for manufacturing a chip having such protrusions, a circuit is formed on the front surface of the semiconductor wafer, and the protrusions are formed on the semiconductor wafer whose thickness is adjusted by grinding the back surface. .. After forming the protrusions, the semiconductor wafer is fixed on the support, and the semiconductor wafer is diced to be individualized into chips. In the obtained set of chips, the surface on which the protrusions are formed is brought into contact with the debond sheet, and the set of chips is transferred from the support to the debond sheet. After the transfer, the set of chips is washed on the debond sheet with a solvent, and then the set of chips is transferred to the pickup sheet and subjected to subsequent steps such as mounting on a substrate.

Here, Cited Document 1 discloses a dicing sheet for fixing a semiconductor wafer during dicing. This dicing sheet is composed of a base material, an intermediate layer formed on the base material, and an adhesive layer formed on the intermediate layer, and the elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. is 5.0 ×. a ^{10 4} ~1.0 × 10 7 Pa, elastic modulus at 23 ° C. of the intermediate layer is less elastic modulus at 23 ° C. of the adhesive layer.

Japanese Unexamined Patent Publication No. 2002-141309

The semiconductor processing sheet for handling the chip on which the protrusion is formed, such as the debond sheet in the above manufacturing method, does not allow the chip to fall off and the solvent does not penetrate around the protrusion during cleaning with the solvent. As described above, proper embedding property of the protrusion is required.

Further, in a chip on which protrusions are formed, defects of the protrusions are likely to occur. In particular, when the protrusions are formed of resin, or when the protrusions are made of metal but have a complicated structure, the protrusions are very fragile. Therefore, it is good so that the protrusions are not damaged in a situation where the surface of the chip on which the protrusions are formed is peeled off from the sheet, such as when the assembly of chips is transferred from the debond sheet to the pickup sheet in the above manufacturing method. Detachability is required for semiconductor processing sheets.

However, the conventional debond sheet and the dicing sheet disclosed in Cited Document 1 are insufficient in the embedding property of the protrusion and the peeling property of the protrusion.

The present invention has been made in view of the above-mentioned actual conditions, and provides a semiconductor processing sheet having excellent embedding property of protrusions such as bumps and peelability of an adherend having protrusions such as bumps. The purpose is to do.

In order to achieve the above object, firstly, in the present invention, the base material, the intermediate layer laminated on one surface side of the base material, and the intermediate layer laminated on the opposite side of the base material are laminated. A semiconductor processing sheet provided with an outermost layer, wherein the outermost layer is made of an energy ray-curable pressure-sensitive adhesive, and the loss tangent at 23 ° C. of the intermediate layer is 0.4 or more, and is used for semiconductor processing. The adhesive strength of the sheet to the silicon mirror wafer before irradiation with energy rays is 12000 mN / 25 mm or more, and the intermediate layer is made of a material whose rheological characteristics do not substantially change even when irradiated with energy rays. Provided is a semiconductor processing sheet (Invention 1).

In the semiconductor processing sheet according to the above invention (Invention 1), the loss tangent of the intermediate layer at 23 ° C. is 0.4 or more, and the adhesive force of the semiconductor processing sheet to the silicon mirror wafer before irradiation with energy rays is high. When it is 12000 mN / 25 mm or more, the embedding property of protrusions such as bumps is improved, the chip is suppressed from falling off, and the infiltration of the solvent around the protrusions is suppressed when cleaning with a solvent. Further, since the intermediate layer is made of a material whose rheological characteristics do not substantially change even when irradiated with energy rays, the defect of protrusions is suppressed when the chip is peeled from the sheet. That is, the semiconductor processing sheet has excellent peelability of an adherend having protrusions such as bumps.

In the above invention (Invention 1), the material is preferably a non-energy ray-curable material or an energy ray-curable material cured (Invention 2).

In the above inventions (Inventions 1 and 2), the thickness of the outermost layer is preferably 1 to 10 μm (Invention 3).

In the above inventions (Inventions 1 to 3), the outermost layer preferably contains an acrylic polymer containing methyl methacrylate as a monomer component (Invention 4).

In the above inventions (Inventions 1 to 4), the outermost layer preferably contains an acrylic polymer into which an energy ray-curable group has been introduced (Invention 5).

In the above inventions (Inventions 1 to 5), the storage elastic modulus at 23 ° C. after irradiation of the outermost layer with energy rays is preferably 270 MPa or less (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable that the semiconductor wafer or the semiconductor chip is a processing sheet having protrusions (Invention 7).

In the above invention (Invention 7), the protrusion is preferably a resin protrusion (Invention 8).

In the above inventions (Inventions 1 to 8), it is preferable to use the semiconductor wafer processing method including a step of bringing the semiconductor processing sheet into contact with an organic solvent while being attached to the semiconductor wafer (Invention 9).

In the above invention (Invention 9), the solubility parameter of the organic solvent is preferably 10 or less (Invention 10).

The semiconductor processing sheet according to the present invention is excellent in embedding property of protrusions such as bumps and peelability of an adherend having protrusions such as bumps.

It is sectional drawing of the semiconductor processing sheet which concerns on one Embodiment of this invention. It is explanatory drawing which shows a part of an example of the semiconductor processing method using the semiconductor processing sheet which concerns on one Embodiment of this invention. It is explanatory drawing which shows a part of an example of the semiconductor processing method using the semiconductor processing sheet which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view of a semiconductor processing sheet according to an embodiment of the present invention. The semiconductor processing sheet 1 according to the present embodiment includes a base material 2, an intermediate layer 3 laminated on one surface side of the base material 2 (upper surface side in FIG. 1), and a base material 2 of the intermediate layer 3. It is configured to include an outermost layer 4 laminated on the opposite side to the above. As an example, the semiconductor processing sheet 1 according to the present embodiment is preferably used as a processing sheet for a semiconductor wafer or a semiconductor chip having protrusions, and in particular, a debond sheet for a semiconductor wafer or a semiconductor chip having protrusions. It is preferably used as such. Hereinafter, a case where the semiconductor processing sheet 1 according to the present embodiment is used as a processing sheet for a semiconductor wafer or a semiconductor chip having protrusions will be described as an example.

In the semiconductor processing sheet 1 according to the embodiment, the outermost layer 4 is made of an energy ray-curable adhesive, the loss tangent of the intermediate layer 3 at 23 ° C. is 0.4 or more, and the energy ray irradiation of the semiconductor processing sheet 1 is performed. The previous adhesive force to the silicon mirror wafer is 12000 mN / 25 mm or more, and the intermediate layer 3 is made of a material whose rheological characteristics do not substantially change even when irradiated with energy rays. When the chip with protrusions is handled by using the semiconductor processing sheet 1 according to the embodiment, the outermost layer 4 of the semiconductor processing sheet 1 and the surface of the chip having the protrusions are brought into contact with each other. At this time, since the loss tangent of the intermediate layer 3 and the adhesive strength of the semiconductor processing sheet 1 are as described above, the protrusions are well embedded in the outermost layer 4, and voids are less likely to occur around the protrusions. Become. Therefore, it is possible to prevent the chip from falling off due to the voids and the solvent from entering the periphery of the protrusion. Further, when the chip with protrusions is peeled off from the semiconductor processing sheet 1, the adhesiveness of the outermost layer 4 can be lowered by irradiating the outermost layer 4 made of the energy ray-curable adhesive with energy rays. This makes it easier to peel off the chip having protrusions. Further, the intermediate layer 3 is made of a material whose rheological characteristics do not substantially change even when irradiated with energy rays, so that the intermediate layer 3 has appropriate softness even after irradiation with energy rays, and the protrusions are formed at room temperature or under heating. When the outermost layer 4 is separated from the surface, the generation of a force that breaks the protrusion can be suppressed as much as possible. As a result, the semiconductor processing sheet 1 can be peeled off without causing the protrusions to be chipped or broken. As described above, the semiconductor processing sheet 1 according to the embodiment is excellent in embedding property of protrusions such as bumps and excellent peelability of an adherend having protrusions such as bumps. The methods for measuring loss tangent and adhesive strength are as shown in the test examples described later.

1. 1. Outermost layer The outermost layer 4 included in the semiconductor processing sheet 1 according to the present embodiment is made of an energy ray-curable pressure-sensitive adhesive. This makes it easy to adjust the adhesive force of the semiconductor processing sheet to the silicon mirror wafer before the energy ray irradiation within the above-mentioned range. On the other hand, before the chip having the protrusion is peeled off from the outermost layer 4, the outermost layer 4 made of the energy ray-curable adhesive is irradiated with energy rays to reduce the adhesiveness of the outermost layer 4. Can be done. Therefore, the protrusions can be easily peeled off without being damaged.

The storage elastic modulus of the outermost layer 4 at 23 ° C. after irradiation with energy rays is preferably 270 MPa or less, more preferably 220 MPa or less. When the storage elastic modulus of the outermost layer 4 is 270 MPa or less, the outermost layer 4 has an appropriate softness, and when the protrusions are pulled away from the surface of the outermost layer 4, a force that breaks the protrusions is generated. Can be further suppressed.

(1) Energy ray-curable adhesive (A)
The energy ray-curable pressure-sensitive adhesive (A) may contain a polymer (A1) into which an energy ray-curable group has been introduced, or may contain energy excluding the polymer (A1) into which an energy ray-curable group has been introduced. It may contain a linear curable compound (A3). When the energy ray-curable pressure-sensitive adhesive (A) in the present embodiment contains the energy ray-curable compound (A3), it also contains a polymer (A2) or the like that does not have energy ray-curable property. Is preferable. In particular, the energy ray-curable pressure-sensitive adhesive (A) is a polymer in which an energy ray-curable group has been introduced because it is easy to control the storage elastic modulus and has excellent coatability and solvent resistance. It is preferable to use A1).

(1-1) Polymer (A1) into which an energy ray-curable group has been introduced.
When the energy ray-curable pressure-sensitive adhesive (A) in the present embodiment contains a polymer (A1) into which an energy ray-curable group has been introduced, such a polymer (A1) is contained as it is in the outermost layer 4. Alternatively, at least a part thereof may be contained as a crosslinked product by undergoing a crosslinking reaction with a crosslinking agent.

Examples of the polymer (A1) into which the energy ray-curable group has been introduced include a functional group-containing acrylic polymer (A1-1) containing a functional group-containing monomer containing a functional group as a constituent, and the functional group. Examples thereof include an acrylic polymer obtained by reacting a functional group that reacts with and a curable group-containing compound (A1-2) having an energy ray-curable carbon-carbon double bond.

The functional group-containing acrylic polymer (A1-1) is a copolymer of an acrylic monomer containing a functional group, an acrylic monomer containing no functional group, and a monomer other than the acrylic monomer, if desired. Is preferable. That is, the functional group-containing monomer is preferably an acrylic monomer containing a functional group.

As the functional group of the acrylic monomer containing a functional group (functional group of the functional group-containing monomer), one capable of reacting with the functional group of the curable group-containing compound (A1-2) is selected. Examples of such a functional group include a hydroxy group, a carboxy group, an amino group, a substituted amino group, an epoxy group and the like, and a hydroxy group is preferable. When the energy ray-curable pressure-sensitive adhesive (A) in the present embodiment contains a cross-linking agent, the functional group-containing acrylic polymer (A1-1) has a functional group that reacts with the cross-linking agent. It is preferable to contain a group-containing monomer as a constituent component, and the functional group-containing monomer may also serve as a functional group-containing monomer having a functional group capable of reacting with the functional group of the curable group-containing compound.

Examples of the hydroxy group-containing acrylic monomer (hydroxy group-containing monomer) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (. Examples thereof include (meth) acrylate hydroxyalkyl esters such as 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among these, 2-hydroxyethyl (meth) acrylate is preferable from the viewpoint of reactivity with the curable group-containing compound (A1-2). These may be used alone or in combination of two or more.

The acrylic monomer containing no functional group preferably contains a (meth) acrylic acid alkyl ester monomer. Examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, n-butyl (meth) acrylic acid, and n-butyl (meth) acrylic acid. Pentyl, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, Examples thereof include palmityl (meth) acrylate and stearyl (meth) acrylate. Among the (meth) acrylic acid alkyl ester monomers, those having an alkyl group having 1 to 18 carbon atoms are preferable, and those having 1 to 10 carbon atoms are particularly preferable. These may be used alone or in combination of two or more. Among the above (meth) acrylic acid alkyl ester monomers, the acrylic polymer constituting the outermost layer 4 preferably contains methyl (meth) acrylate as a monomer component, and particularly preferably contains methyl methacrylate. preferable. This is the resistance of the semiconductor processing sheet 1 to the organic solvent when it is used in a semiconductor wafer processing method including a step of bringing the semiconductor processing sheet 1 into contact with an organic solvent while the semiconductor processing sheet 1 is attached to the semiconductor wafer. In particular, the solubility parameter is based on the viewpoint that resistance to an organic solvent showing a low value such as 10 or less can be easily achieved. By using a material that easily achieves resistance to organic solvents for the outermost layer 4, the solvent resistance of the semiconductor processing sheet 1 can be improved even when a material having low solvent resistance is used as the material of the intermediate layer 3. Can be enhanced.

In addition to the above-mentioned (meth) acrylic acid alkyl ester monomer, the acrylic monomer containing no functional group includes, for example, methoxymethyl (meth) acrylic acid, methoxyethyl (meth) acrylic acid, ethoxymethyl (meth) acrylic acid, ( An alkoxyalkyl group-containing (meth) acrylic acid ester such as ethoxyethyl acrylate, a (meth) acrylic acid ester having an aromatic ring such as phenyl (meth) acrylic acid, and a non-crosslinkable acrylamide such as acrylamide and methacrylic acid. , (Meta) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid N, N-dimethylaminopropyl and the like (meth) acrylic acid ester having a non-crosslinkable tertiary amino group may be contained.

Examples of the monomer other than the acrylic monomer include olefins such as ethylene and norbornene, vinyl acetate, styrene and the like.

The ratio of the mass of the structural portion derived from the functional group-containing monomer to the total mass of the functional group-containing acrylic polymer (A1-1) in the functional group-containing acrylic polymer (A1-1) is 0.1 to 50. It is preferably by mass, particularly preferably 1 to 40% by mass, and even more preferably 3 to 30% by mass. Thereby, the amount of the curable group introduced by the curable group-containing compound (A1-2) (and the amount of reaction with the cross-linking agent) is adjusted to a desired amount, and the degree of curing of the outermost layer 4 obtained is in a preferable range. Can be controlled to. As a result, it becomes easy to adjust the storage elastic modulus at 23 ° C. after the above-mentioned energy ray irradiation of the outermost layer 4.

The functional group-containing acrylic polymer (A1-1) can be obtained by copolymerizing each of the above monomers by a conventional method. The polymerization mode of the functional group-containing acrylic polymer (A1-1) may be a random copolymer or a block copolymer.

The curable group-containing compound (A1-2) has a functional group that reacts with the functional group of the functional group-containing acrylic polymer (A1-1) and an energy ray-curable carbon-carbon double bond. Examples of the functional group that reacts with the functional group of the functional group-containing acrylic polymer (A1-1) include an isocyanate group, an epoxy group, a carboxy group and the like, and among them, an isocyanate group having high reactivity with a hydroxy group. Is preferable.

The curable group-containing compound (A1-2) preferably contains 1 to 5 energy ray-curable carbon-carbon double bonds for each molecule of the curable group-containing compound (A1-2), particularly 1 It is preferable to contain ~ 2.

Examples of such a curable group-containing compound (A1-2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1- (bis). Acryloyloxymethyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, (meth) acrylic acid Examples thereof include an acryloyl monoisocyanate compound obtained by reacting with hydroxyethyl. Of these, 2-methacryloyloxyethyl isocyanate is particularly preferable. As the curable group-containing compound (A1-2), one type may be used alone, or two or more types may be used in combination.

The polymer (A1) into which the energy ray-curable group has been introduced has a curable group derived from the curable group-containing compound (A1-2), and the functional group-containing acrylic polymer (A1-1) has a functional group. 20 to 120 mol% (mol% is a curable group with respect to the number of moles of the functional group of the polymer (A1)) with respect to (a functional group that reacts with the functional group of the curable group-containing compound (A1-2)). The ratio of the number of moles of the curable group of the contained compound (A1-2) is shown as a percentage.) It is preferable to contain the compound (A1-2), particularly 35 to 100 mol%, and further 50 to 100. It is preferably contained in mol%. When the polymer (A1) has a curable group in an amount in such a range, it becomes easy to adjust the storage elastic modulus at 23 ° C. after the above-mentioned energy ray irradiation of the outermost layer 4. When the curable group-containing compound (A1-2) is monofunctional, the upper limit is 100 mol%, but when the curable group-containing compound (A1-2) is polyfunctional, it exceeds 100 mol%. Sometimes. When the ratio of the curable group to the functional group is within the above range, the storage elastic modulus of the outermost layer 4 after the energy ray curing can be set to an appropriate value.

The weight average molecular weight (Mw) of the polymer (A1) into which the energy ray-curable group has been introduced is preferably 100,000 to 2 million, more preferably 300,000 to 1.5 million. The weight average molecular weight in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

(1-2) Polymer (A2) having no energy ray curability
When the energy ray-curable pressure-sensitive adhesive (A) in the present embodiment contains a polymer (A2) having no energy ray-curable property, the polymer (A2) may be contained as it is in the outermost layer 4. In addition, at least a part thereof may be contained as a crosslinked product by undergoing a crosslinking reaction with a crosslinking agent. Examples of the polymer (A2) include phenoxy resin, acrylic polymer (A2-1), urethane resin, polyester resin, rubber resin, acrylic urethane resin and the like. Of these, the case where the acrylic polymer (A2-1) is used will be described in detail.

As the acrylic polymer (A2-1), a conventionally known acrylic polymer can be used. The acrylic polymer (A2-1) may be a homopolymer formed from one type of acrylic monomer, or may be a copolymer formed from a plurality of types of acrylic monomers. It may be a copolymer formed from one kind or a plurality of kinds of acrylic monomers and monomers other than acrylic monomers. The specific type of the compound serving as the acrylic monomer is not particularly limited, and specific examples thereof include (meth) acrylic acid, (meth) acrylic acid ester, and derivatives thereof (acrylonitrile, itaconic acid, etc.). To give a more specific example of (meth) acrylic acid ester, methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, butyl (meth) acrylic acid, (meth) acrylic acid. (Meta) acrylate having a chain skeleton such as 2-ethylhexyl; cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (Meta) Acrylic acid ester having a cyclic skeleton such as tetrahydrofurfuryl (meth) acrylate, imide acrylate; having a hydroxy group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate. (Meta) acrylic acid ester; examples thereof include (meth) acrylic acid ester having a reactive functional group other than the hydroxy group such as glycidyl (meth) acrylic acid and N-methylaminoethyl (meth) acrylic acid. Further, examples of the monomer other than the acrylic monomer include olefins such as ethylene and norbornene, vinyl acetate, and styrene. When the acrylic monomer is a (meth) acrylic acid alkyl ester, the number of carbon atoms of the alkyl group is preferably in the range of 1 to 18. Among the above (meth) acrylic acid esters, the outermost layer 4 is selected from the viewpoint of easily achieving resistance to an organic solvent of the semiconductor processing sheet 1, particularly resistance to an organic solvent having a solubility parameter of 10 or less. The constituent acrylic polymer preferably contains methyl (meth) acrylate as a monomer component, and particularly preferably contains methyl methacrylate.

When the energy ray-curable pressure-sensitive adhesive (A) in the present embodiment contains a cross-linking agent, the acrylic polymer (A2-1) preferably has a reactive functional group that reacts with the cross-linking agent. The type of the reactive functional group is not particularly limited, and may be appropriately determined based on the type of the cross-linking agent and the like.

For example, when the cross-linking agent is a polyisocyanate compound, hydroxy group, carboxy group, amino group and the like are exemplified as the reactive functional group of the acrylic polymer (A2-1), and among them, the reaction with the isocyanate group. A hydroxy group having a high property is preferable. When the cross-linking agent is an epoxy compound, examples of the reactive functional group of the acrylic polymer (A2-1) include a carboxy group, an amino group and an amide group, and among them, a reaction with an epoxy group. A carboxy group having a high property is preferable.

The method for introducing a reactive functional group into the acrylic polymer (A2-1) is not particularly limited, and as an example, an acrylic polymer (A2-1) is formed using a monomer having a reactive functional group. Examples thereof include a method in which a structural unit based on a monomer having a reactive functional group is contained in the skeleton of the polymer. For example, when a hydroxy group is introduced into an acrylic polymer (A2-1), an acrylic polymer (A2-1) is formed using a monomer having a hydroxy group such as 2-hydroxyethyl (meth) acrylate. do it.

When the acrylic polymer (A2-1) has a reactive functional group, the reactive functional group occupies the total mass of the acrylic polymer (A2-1) from the viewpoint of keeping the degree of cross-linking in a good range. The proportion of the mass of the structural portion derived from the monomer having the above is preferably about 1 to 20% by mass, and more preferably 2 to 10% by mass.

The weight average molecular weight (Mw) of the acrylic polymer (A2-1) is preferably 10,000 to 2 million, more preferably 100,000 to 1,500,000 from the viewpoint of film-forming property at the time of coating. ..

(1-3) Energy ray curable compound (A3)
The energy ray-curable pressure-sensitive adhesive (A) may contain an energy ray-curable compound (A3) excluding the polymer (A1) into which the energy ray-curable group has been introduced. In this case, the above-mentioned energy ray-curable pressure-sensitive adhesive (A3) may be contained. It is preferable to also contain a polymer (A2) having no energy ray curability. Further, the polymer (A1) into which an energy ray-curable group has been introduced may be contained in place of or together with the polymer (A2) having no energy ray-curable property. The energy ray-curable compound (A3) is a compound having an energy ray-curable group and polymerizing when irradiated with energy rays.

The energy ray-curable group contained in the energy ray-curable compound (A3) is, for example, a group containing an energy ray-curable carbon-carbon double bond, and specifically, a (meth) acryloyl group, a vinyl group, or the like. It can be exemplified.

Examples of the energy ray-curable compound (A3) are not particularly limited as long as they have the above-mentioned energy ray-curable group, but from the viewpoint of versatility, low molecular weight compounds (monofunctional, polyfunctional monomers and oligomers). Is preferable. Specific examples of the low molecular weight energy ray-curable compound (A3) include trimethyl propantriacrylate, tetramethylolmethanetetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, or 1, Cyclic aliphatic skeleton-containing acrylates such as 4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, dicyclopentadiene dimethoxydiacrylate, and isobornyl acrylate, polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate oligomer, epoxy. Examples thereof include acrylate-based compounds such as modified acrylates, polyether acrylates, and itaconic acid oligomers.

Further, examples of the energy ray-curable compound (A3) include an epoxy resin having an energy ray-curable group, a phenol resin having an energy ray-curable group, and the like. As such a resin, for example, those described in JP-A-2013-194102 can be used.

The energy ray-curable compound (A3) usually has a molecular weight of 100 to 30,000, preferably about 300 to 10,000. Generally, the energy ray-curable compound (A3) is contained in an amount of 10 to 400 parts by mass, preferably about 30 to 350 parts by mass, based on 100 parts by mass of the total amount of the polymer (A1) and the polymer (A2). Used.

The outermost layer 4 according to the present embodiment preferably contains the energy ray-curable pressure-sensitive adhesive (A) in an amount of 5 to 89% by mass, particularly preferably 10 to 80% by mass, and further preferably 20 to 70% by mass. It is preferable to contain it. When the content of the energy ray-curable pressure-sensitive adhesive (A) is within the above range, it can be appropriately cured by energy ray irradiation.

(2) Cross-linking agent Examples of the cross-linking agent include polyimine compounds such as epoxy compounds, polyisocyanate compounds, metal chelate compounds, and aziridine compounds, melamine resins, urea resins, dialdehydes, methylol polymers, and metals. Examples thereof include alkoxides and metal salts. Among these, an epoxy compound or a polyisocyanate compound is preferable, and a polyisocyanate compound is particularly preferable, because the cross-linking reaction can be easily controlled.

Examples of the epoxy compound include 1,3-bis (N, N'-diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylene diamine, and ethylene glycol diglycidyl ether. , 1,6-Hexanediol diglycidyl ether, trimethylpropan diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

The polyisocyanate compound is a compound having two or more isocyanate groups per molecule. Specifically, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanates, and the like, and their like. Examples thereof include a biuret form, an isocyanurate form, and an adduct form which is a reaction product with a low molecular weight active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.

As the cross-linking agent, one type may be used alone, or two or more types may be used in combination.

When the outermost layer 4 made of the (meth) acrylic acid ester copolymer (A) is formed, the amount of the cross-linking agent used is 100 parts by mass of the (meth) acrylic acid ester copolymer (A). , 0.05 to 15 parts by mass, particularly preferably 0.1 to 8 parts by mass, and further preferably 0.2 to 3 parts by mass. When the amount of the cross-linking agent is in such a range, it is easy to adjust the adhesive force of the semiconductor processing sheet 1 to the silicon mirror wafer before the energy ray irradiation and the storage elastic modulus of the outermost layer 4 after the energy ray irradiation. Therefore, after the semiconductor processing sheet 1 is manufactured, the adhesive properties are stabilized without requiring an excessively long curing period.

When the outermost layer 4 is formed by using a cross-linking agent, it is preferable to use an appropriate cross-linking accelerator depending on the type of the cross-linking agent and the like. For example, when the cross-linking agent is a polyisocyanate compound, it is preferable to use an organometallic compound-based cross-linking accelerator such as an organotin compound.

(3) Other components When forming the outermost layer 4, in addition to the above components, various additives such as a photopolymerization initiator, a coloring material such as a dye or a pigment, a flame retardant, and a filler may be used.

Specific examples of the photopolymerization initiator include photoinitiators such as benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanosen compounds, thioxanthone compounds and peroxide compounds, and photosensitizers such as amines and quinones. Α-Hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenyl sulfate, tetramethylthium monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone. , 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like are exemplified. When ultraviolet rays are used as energy rays, the irradiation time and irradiation amount can be reduced by adding a photopolymerization initiator.

(4) Irradiation of energy rays Examples of the energy rays for curing the outermost layer 4 include ionizing radiation, that is, ultraviolet rays, electron beams, X-rays, and the like. Of these, ultraviolet rays, which are relatively easy to introduce irradiation equipment, are preferable.

When ultraviolet rays are used as ionizing radiation, it is preferable to use near-ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm for ease of handling. The amount of light may be appropriately selected according to the type of energy ray-curable group possessed by the outermost layer 4 and the thickness of the semiconductor processing sheet 1, and is usually ^{about 50 to 500 mJ / cm 2} and 100 to 450 mJ /. cm ² is preferable, and 200 to 400 mJ / cm ² is more preferable. The ultraviolet illumination is usually 50 to 500 mW / cm ² or so, preferably from ^{100~450mW / cm 2, 200~400mW / cm} 2 is more preferable. The ultraviolet source is not particularly limited, and for example, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like is used.

When an electron beam is used as the ionizing radiation, the acceleration voltage may be appropriately selected according to the type of energy ray-curable group possessed by the outermost layer 4 and the thickness of the semiconductor processing sheet 1, and is usually accelerated. The voltage is preferably about 10 to 1000 kV. Further, the irradiation dose may be set in a range in which the outermost layer 4 is appropriately cured, and is usually selected in the range of 10 to 1000 grad. The electron beam source is not particularly limited, and for example, various electron beam accelerators such as cockloft Walton type, bandegraft type, resonance transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type are used. be able to.

(5) Thickness of the outermost layer 4 The thickness of the outermost layer 4 in the present embodiment is preferably 30 μm or less, more preferably 10 μm or less, and particularly preferably 8 μm or less. In particular, when the thickness of the outermost layer 4 is 10 μm or less, the peelability when peeling the chip is further improved. In the present embodiment, as described above, the semiconductor processing sheet 1 needs to have a high adhesive force to the silicon mirror wafer before irradiation with energy rays. Therefore, it is necessary to use a highly adhesive adhesive, and it may not be easy to improve the peelability of the chip having protrusions even after irradiation with energy rays. However, by reducing the thickness of the outermost layer 4 to about 10 μm or less, it is possible to improve the peelability of the chip having protrusions even when a highly adhesive adhesive is used. On the other hand, the thickness of the outermost layer 4 is preferably 1 μm or more, and particularly preferably 3 μm or more, from the viewpoint of further enhancing the effect of the outermost layer 4 being made of the energy ray-curable pressure-sensitive adhesive.

2. 2. Intermediate layer In the intermediate layer 3 included in the semiconductor processing sheet 1 according to the present embodiment, the loss tangent at 23 ° C. is 0.4 or more, preferably 0.5 or more. The loss tangent is also expressed as tan δ and is defined as the value obtained by dividing the value of the loss modulus (G ″) by the value of the storage modulus (G ′). When the loss tangent at 23 ° C. is 0.4 or more, the generation of voids around the protrusions can be minimized when embedding the protrusions, and the chips fall off and the solvent goes around the protrusions. Intrusion is prevented. As a result, excellent implantability of protrusions is achieved.

The intermediate layer 3 is made of a material whose rheological characteristics do not substantially change even when irradiated with energy rays. For example, the material of the intermediate layer 3 is a non-energy ray-curable material (non-energy ray-curable material), or is an energy ray-curable material, but is used as a sheet 1 for semiconductor processing. Since the material has already been irradiated with energy rays and has been cured, a chemical reaction is unlikely to occur even if it receives energy rays, and the rheological characteristics do not substantially change. Since the intermediate layer 3 is made of such a material, it is possible to prevent the intermediate layer 3 from being cured when the outermost layer 4 is cured by irradiating it with energy rays when the chip is peeled off. As a result, the outermost layer 4 and the intermediate layer 3 which are the layers for embedding the protrusions are not excessively cured as a whole, and better peeling of the chip is possible.

As the material of the intermediate layer 3, for example, a (meth) acrylic acid ester polymer (acrylic polymer), a cured composition containing a urethane polymer, a hot meltable olefin, or the like can be used. Among the above, an acrylic polymer or a urethane polymer is preferable, and an acrylic polymer having no energy ray curability is particularly preferable. These materials may be used alone or in combination of two or more. Further, these materials may be contained in the intermediate layer 3 as they are, or at least a part thereof may be contained as a crosslinked product by undergoing a crosslinking reaction with a crosslinking agent.

As the acrylic polymer, a conventionally known acrylic polymer can be used. The acrylic polymer may be a homopolymer formed from one type of acrylic monomer, a copolymer formed from a plurality of types of acrylic monomers, one type or a plurality of types. It may be a copolymer formed from a kind of acrylic monomer and a monomer other than the acrylic monomer. The specific type of the compound serving as the acrylic monomer is not particularly limited, and specific examples thereof include (meth) acrylic acid, (meth) acrylic acid ester, and derivatives thereof (acrylonitrile, itaconic acid, etc.). To give a more specific example of (meth) acrylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate. (Meta) acrylic acid ester having a chain skeleton such as (meth) cyclohexyl acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) (Meta) acrylic acid ester having a cyclic skeleton such as tetrahydrofurfuryl acrylate and imide acrylate; (meth) having a hydroxy group such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Acrylic acid ester; Examples thereof include (meth) acrylic acid ester having a reactive functional group other than the hydroxy group such as glycidyl (meth) acrylic acid and N-methylaminoethyl (meth) acrylic acid. Further, examples of the monomer other than the acrylic monomer include olefins such as ethylene and norbornene, vinyl acetate, and styrene. When the acrylic monomer is a (meth) acrylic acid alkyl ester, the number of carbon atoms of the alkyl group is preferably in the range of 1 to 18.

When the material of the intermediate layer 3 is subjected to a cross-linking reaction using a cross-linking agent, the acrylic polymer preferably has a reactive functional group that reacts with the cross-linking agent. The type of the reactive functional group is not particularly limited, and may be appropriately determined based on the type of the cross-linking agent and the like.

For example, when the cross-linking agent is an epoxy-based compound, carboxyl groups, amino groups, amide groups and the like are exemplified as the reactive functional groups of the acrylic polymer, and among them, the carboxyl group having high reactivity with the epoxy group. Is preferable. When the cross-linking agent is a polyisocyanate compound, hydroxy groups, carboxyl groups, amino groups and the like are exemplified as the reactive functional groups of the acrylic polymer, and among them, the hydroxy group having high reactivity with the isocyanate group. Is preferable.

The method for introducing a reactive functional group into the acrylic polymer is not particularly limited, and as an example, an acrylic polymer is formed using a monomer having a reactive functional group, and a configuration based on the monomer having a reactive functional group is formed. Examples thereof include a method in which the unit is contained in the skeleton of the polymer. For example, when a carboxyl group is introduced into an acrylic polymer, the acrylic polymer may be formed by using a monomer having a carboxyl group such as (meth) acrylic acid.

When the acrylic polymer has a reactive functional group, from the viewpoint of keeping the degree of cross-linking in a good range, the mass of the structural portion derived from the monomer having the reactive functional group in the total mass of the acrylic polymer The ratio is preferably about 1 to 20% by mass, and more preferably 2 to 10% by mass.

The weight average molecular weight (Mw) of the acrylic polymer is preferably 10,000 to 2 million, more preferably 100,000 to 1,500,000 from the viewpoint of film-forming property at the time of coating. The weight average molecular weight in the present specification is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method. The glass transition temperature Tg of the acrylic polymer is preferably in the range of −70 ° C. to 30 ° C., more preferably −60 ° C. to 20 ° C. The glass transition temperature can be calculated from the Fox equation.

Examples of the cured composition containing a urethane-based polymer include a cured product obtained by energy ray-curing a composition containing a urethane (meth) acrylate oligomer and an energy ray-curable monomer.

The urethane (meth) acrylate oligomer is obtained by reacting a (meth) acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting, for example, a polyol compound with a polyisocyanate compound.

As a condition for reacting the terminal isocyanate urethane prepolymer and the (meth) acrylate having a hydroxy group, the terminal isocyanate urethane prepolymer and the (meth) acrylate having a hydroxy group can be mixed with a solvent and a catalyst, if necessary. In the presence, the reaction may be carried out at about 60 to 100 ° C. for about 1 to 4 hours.

The obtained urethane (meth) acrylate oligomer has a photopolymerizable double bond in the molecule, and has a property of polymerizing and curing by energy ray irradiation to form a film.

The above urethane (meth) acrylate oligomers can be used alone or in combination of two or more. In order to make film formation easier than in the case of urethane (meth) acrylate oligomer alone as described above, an energy ray-curable monomer is mixed with urethane (meth) acrylate oligomer to form a film, which is then cured and intermediate. Layer 3 may be obtained. The energy ray-curable monomer has an energy ray-polymerizable double bond in the molecule, and a (meth) acrylic acid ester compound is preferably used, and in particular, an alicyclic structure having a relatively bulky group. A (meth) acrylic acid ester having an aromatic structure, a (meth) acrylic acid ester having an aromatic structure, a (meth) acrylic acid ester having a heterocyclic structure, and the like are preferably used.

As a film-forming method, a method called casting film-forming (cast film-forming) can be preferably adopted. Specifically, a liquid composition (a liquid product obtained by diluting a mixture of the above components with a solvent if necessary) is cast into a thin film on, for example, a process sheet, and then the coating film is irradiated with energy rays to polymerize. It is cured to form a film. Specifically, ultraviolet rays, electron beams, and the like are used as the energy rays. Further, the irradiation amount is different depending on the type of the energy ray, for example, when ultraviolet rays are used, the ultraviolet intensity is 50~300mW / cm ^2, the amount of ultraviolet irradiation is preferably about 100~1200mJ / cm ^2.

When ultraviolet rays are used as energy rays during film formation, a urethane (meth) acrylate oligomer or an energy ray-curable monomer can be efficiently reacted by blending a known photopolymerization initiator with the composition. Further, in order to control the reactivity of the urethane (meth) acrylate oligomer or the energy ray-curable monomer, a chain transfer agent may be added to the composition. Examples of the chain transfer agent include thiol compounds.

Alternatively, a non-reactive urethane polymer may be used instead of the urethane (meth) acrylate oligomer to prepare a mixture with the energy ray-curable monomer, and the intermediate layer 3 may be formed from this mixture.

Although the material of the intermediate layer 3 is an energy ray-curable material, when a material that has already been irradiated with energy rays and cured at the stage of being used as the semiconductor processing sheet 1, the outermost layer 4 is used. The above-mentioned energy ray-curable pressure-sensitive adhesive (A) may be cured by irradiating with energy rays.

As the cross-linking agent contained in the intermediate layer 3, the same cross-linking agent as that contained in the outermost layer 4 can be used.

Further, in the intermediate layer 3, in addition to the above components, various additives such as a photopolymerization initiator, a coloring material such as a dye or a pigment, a flame retardant, and a filler may be used. As the photopolymerization initiator, the same photopolymerization initiator contained in the outermost layer 4 can be used.

The thickness of the intermediate layer 3 is preferably 20 to 200 μm, particularly preferably 30 to 100 μm. When it is 20 μm or more, the embedding property of the protrusion is improved, and when it is 200 μm or less, it is prevented that the semiconductor processing sheet 1 becomes too thick, and the manufacturing cost can be suppressed.

3. 3. Base material The base material 2 of the semiconductor processing sheet 1 according to the present embodiment is not particularly limited as long as it is suitable for processing such as solvent cleaning of a semiconductor wafer or a semiconductor chip, and is usually a resin-based material. It is composed of a film whose main material is (hereinafter referred to as "resin film").

Specific examples of the resin film include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film, polypropylene film, polybutene film, polybutadiene film, and polymethylpentene film. , Ethethylene-norbornene copolymer film, polyolefin-based film such as norbornene resin film; ethylene-vinyl acetate copolymer film, ethylene- (meth) acrylic acid copolymer film, ethylene- (meth) acrylic acid ester copolymer Ethylene-based copolymer films such as films; polyvinyl chloride-based films such as polyvinyl chloride films and vinyl chloride copolymer films; polyester-based films such as polyethylene terephthalate films and polybutylene terephthalate films; polyurethane films; polyimide films; polystyrene films ; Polycarbonate film; Fluororesin film and the like. Further, modified films such as these crosslinked films and ionomer films are also used. The base material 2 may be a film composed of one of these types, or may be a laminated film in which two or more types of these are combined. Among the above, a polyester-based film is preferable from the viewpoint of solvent resistance and the like, and a polybutylene terephthalate film is particularly preferable.

For the purpose of improving the adhesion to the intermediate layer 3 laminated on the surface of the resin film, one or both sides of the resin film can be surface-treated by an oxidation method, an unevenness method, or a primer treatment, if desired. .. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment, and examples of the unevenness method include sandblasting and sandblasting. Examples include a thermal spraying method.

The base material 2 may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler in the resin film.

When ultraviolet rays are used as the energy rays to be irradiated to cure the outermost layer 4, the base material 2 preferably has transparency to the ultraviolet rays. When an electron beam is used as the energy ray, it is preferable that the base material 2 has the transparency of the electron beam.

The thickness of the base material 2 is not particularly limited as long as it can function appropriately in each step in which the semiconductor processing sheet 1 is used. It is preferably in the range of 20 to 450 μm, more preferably 25 to 400 μm, and particularly preferably 50 to 350 μm.

4. Release sheet The semiconductor processing sheet 1 according to the present embodiment is on the side opposite to the surface of the outermost layer 4 on the base material 2 side for the purpose of protecting the outermost layer 4 until the outermost layer 4 is attached to the adherend. A release sheet may be laminated on the surface of the surface. The structure of the release sheet is arbitrary, and examples thereof include a plastic film peeled with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, a silicone type, a fluorine type, a long chain alkyl type or the like can be used, but among these, a silicone type that can obtain stable performance at low cost is preferable. The thickness of the release sheet is not particularly limited, but is usually about 20 to 250 μm.

5. Physical Properties of Semiconductor Processing Sheet The adhesive strength of the semiconductor processing sheet 1 to the silicon mirror wafer before irradiation with energy rays is 12000 mN / 25 mm or more, preferably 15000 mN / 25 mm or more. When the adhesive force of the outermost layer 4 before irradiation with energy rays is 12000 mN / 25 mm or more, the embedding of the protrusions in the outermost layer 4 becomes good, and the protrusions and the outermost layer 4 are sufficiently adhered and adhered. It is prevented from peeling off spontaneously later. As a result, voids are less likely to be generated around the protrusions, the chips are prevented from falling off due to the voids, and the solvent is prevented from entering the periphery of the protrusions, and excellent embedding properties of the protrusions are achieved.

6. Method for Manufacturing Semiconductor Processing Sheet The semiconductor processing sheet 1 can be manufactured, for example, as follows.

A composition containing the material of the intermediate layer 3 and, if desired, a coating composition further containing a solvent or a dispersion medium are prepared, and a die coater, a curtain coater, a spray coater, a slit coater, a knife coater, etc. are prepared on the process film. The coating composition is applied to form a coating film, and the coating film is dried to form an intermediate layer 3 on the process film. As the process film, a release sheet having the same structure as described above can be used, and it is preferable to apply the coating composition on the release surface in that structure.

Next, by sticking the surface of the intermediate layer 3 opposite to the process film and one surface of the base material 2, a laminate in which the process film, the intermediate layer 3 and the base material 2 are laminated in order is obtained.

On the other hand, a composition containing the material of the outermost layer 4 and, if desired, a coating composition further containing a solvent or a dispersion medium are prepared, and a die coater, The coating composition is applied by a curtain coater, a spray coater, a slit coater, a knife coater, or the like to form a coating film, and the coating film is dried to form the outermost layer 4 on the release sheet. The properties of the coating composition are not particularly limited as long as it can be applied, and the component for forming the outermost layer 4 may be contained as a solute or as a dispersoid. In some cases.

In the laminate of the process film produced as described above, the intermediate layer 3 and the base material 2, the surface of the intermediate layer 3 exposed by peeling the process film is opposite to the release sheet of the outermost layer 4 produced as described above. By sticking the surface of the outermost layer 4, the outermost layer 4, the intermediate layer 3, and the base material 2 are laminated in this order, that is, the surface of the outermost layer 4 opposite to the intermediate layer 3 is protected by the release sheet. The semiconductor processing sheet 1 in the finished state is obtained.

As another manufacturing method of the semiconductor processing sheet 1, it can also be manufactured by laminating the intermediate layer 3 and the outermost layer 4 in order on the base material 2. For example, the coating composition containing the material of the intermediate layer 3 can be applied on one surface of the base material 2 with a die coater or the like and dried to form the intermediate layer 3 on the base material 2. it can. Further, the coating composition containing the material of the outermost layer 4 is applied on the surface of the intermediate layer 3 opposite to the base material 2 by a die coater or the like, and dried to obtain the outermost layer 4 on the intermediate layer 3. Can be formed. As a result, the semiconductor processing sheet 1 in which the outermost layer 4, the intermediate layer 3, and the base material 2 are laminated in this order can be obtained.

As yet another method for producing the semiconductor processing sheet 1, the coating composition for the outermost layer 4 is applied on the peeled surface of the above-mentioned release sheet to form a coating film, which is dried, and further, the outermost layer 4 is formed. The coating composition for the intermediate layer 3 is applied on the surface opposite to the release sheet of No. 3 to form a coating film and dried to form a laminate composed of the intermediate layer 3, the outermost layer 4, and the release sheet. Then, the surface of the intermediate layer 3 of the laminated body opposite to the surface on the release sheet side may be attached to the base material 2 to obtain a laminate of the semiconductor processing sheet 1 and the release sheet. The release sheet in this laminated body may be peeled off as a process material, or the outermost layer 4 may be protected until it is attached to an adherend such as a semiconductor wafer or a chip.

When the coating composition contains a cross-linking agent, the cross-linking reaction between the polymer and the cross-linking agent can be carried out by changing the above drying conditions (temperature, time, etc.) or by separately providing a heat treatment. It may be advanced to form a crosslinked structure in the intermediate layer 3 and the outermost layer 4 at a desired abundance density. In order to allow the cross-linking reaction to proceed sufficiently, usually, after laminating the intermediate layer 3 and the outermost layer 4 on the base material 2 by the above method or the like, the obtained semiconductor processing sheet 1 is heated to, for example, 23 ° C. It is cured by letting it stand in an environment with a relative humidity of 50% for several days.

7. How to Use the Semiconductor Processing Sheet With reference to FIGS. 2 and 3, an example of using the semiconductor processing sheet 1 according to the present embodiment as a debond sheet when manufacturing a chip having protrusions will be described below. To do.

First, as shown in FIG. 2A, the back surface grinding step is performed on the wafer 21 fixed on the hard support 22, and the thickness of the wafer 21 is reduced.

Next, as shown in FIG. 2B, by forming the protrusions 23 on the wafer 21, the wafer 20W with protrusions is obtained. When the protrusion 23 is a bump, it is preferably made of metal, but in other applications, it may be made of resin. With the semiconductor processing sheet 1 according to the present embodiment, even resin protrusions that are easily damaged can be handled without being damaged.

Next, as shown in FIG. 2C, a dicing step is performed on the wafer 20W with protrusions to obtain a plurality of chips 20C from the wafer 20W with protrusions.

Next, as shown in FIG. 2D, the plurality of chips 20C supported by the hard support 22 are turned upside down and the surface of the semiconductor processing sheet 1 on the outermost layer 4 side (that is, the outermost layer). It is attached to the surface of No. 4 opposite to the base material 2). The peripheral edge portion of the semiconductor processing sheet 1 is usually attached to the ring frame 24a by the outermost layer 4 provided in that portion. Since the outermost layer 4 of the semiconductor processing sheet 1 has a protrusion embedding property, the protrusion 23 of the chip 20C is satisfactorily embedded in the outermost layer 4. As a result, the chip 20C is in close contact with the outermost layer 4 of the semiconductor processing sheet 1 and is prevented from falling off.

Next, as shown in FIG. 3A, the hard support 22 is removed. At this time, for example, the hard support 22 is removed by peeling from the plurality of chips 20C.

Next, as shown in FIG. 3B, the cleaning device 25 is used to clean the chip 20C with an organic solvent. In the semiconductor processing sheet 1 according to the embodiment, since the protrusions are satisfactorily embedded in the outermost layer 4, the infiltration of the organic solvent into the periphery of the protrusions is prevented. The solubility parameter of the organic solvent used at this time is preferably 10 or less, particularly preferably 9 or less, and further preferably 8 or less.

Next, as shown in FIG. 3C, the cleaning device 25 is separated. Further, a plurality of chips 20C are attached to the pickup sheet 26. Specifically, the surface on which the protrusions 23 of the plurality of chips 20C are not formed and one surface of the pickup sheet 26 are attached. After that, energy rays are irradiated from the base material 2 side of the semiconductor processing sheet 1 to promote the polymerization reaction of the energy ray-curable groups contained in the outermost layer 4, and reduce the adhesiveness. This facilitates the peeling of the chip 20C from the outermost layer 4.

Finally, as shown in FIG. 3D, the pickup sheet 26 is peeled off from the semiconductor processing sheet 1 together with the plurality of chips 20C. A ring frame 24b is usually attached to the peripheral edge of the pickup sheet 26. At the time of peeling, the semiconductor processing sheet 1 is heated if necessary. In this case, by selecting the outermost layer 4 having a storage elastic modulus in the same range as the storage elastic modulus at 23 ° C. described above at the heated temperature, it is suitable for separation accompanied by heating of the protrusions. It can give softness. Therefore, it becomes easy to peel off without causing the protrusions to be chipped or broken.

Hereinafter, although not shown, the individual chips 20C are picked up from the pickup sheet 26 and subjected to the process of mounting on the substrate.

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

For example, another layer may be interposed between the base material 2 and the intermediate layer 3 and / or between the intermediate layer 3 and the outermost layer 4 in the semiconductor processing sheet 1.

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

[Example 1]
(1) Preparation of Intermediate Layer 90 parts by mass of n-butyl acrylate (solid content conversion value; hereinafter referred to in the same manner) and 10 parts by mass of acrylic acid were copolymerized to obtain an acrylic copolymer. 100 parts by mass of this acrylic polymer and 0.3 parts by mass of a toluene diisocyanate (TDI) -based cross-linking agent (BHS8515, manufactured by Toyo Ink Co., Ltd.) were mixed in a solvent to obtain a coating solution for an intermediate layer.

The obtained coating solution was applied to the peeling surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET38131", thickness: 38 μm) as a process film in which one side of a polyethylene terephthalate film was peeled with a silicone-based release agent. After coating with a knife coater, the mixture was treated at 100 ° C. for 1 minute to form an intermediate layer having a thickness of 50 μm.

(2) Preparation of Laminate of Intermediate Layer and Base Material By laminating the obtained intermediate layer with a polybutylene terephthalate (PBT) film (thickness: 80 μm) as a base material, the base material in the intermediate layer A laminate of the intermediate layer and the base material was obtained in a state where the release sheet as the process film was laminated on the surface opposite to the side surface.

(3) Preparation of outermost layer 69 parts by mass of 2-ethylhexyl acrylate (solid content conversion value; the same applies hereinafter), 10 parts by mass of methyl methacrylate, 20 parts by mass of 2-hydroxyethyl acrylate, and 1 part of acrylic acid. The part by mass was copolymerized to obtain an acrylic copolymer.

Next, the obtained acrylic copolymer was reacted with 2-methacryloyloxyethyl isocyanate (MOI; A3) to obtain a polymer in which an energy ray-curable group (methacryloyl group) was introduced into the side chain. .. At this time, the two are reacted so that the MOI is 21.4 g per 100 g of the acrylic copolymer (80 mol (80 mol%) per 100 mol of 2-hydroxyethyl acrylate unit of the acrylic copolymer). It was. When the molecular weight of the obtained polymer into which the energy ray-curable group was introduced was measured by the method described later, the weight average molecular weight (Mw) was 600,000. In any of the following Examples / Comparative Examples, the weight average molecular weight (Mw) of the polymer into which the energy ray-curable group was introduced was 600,000.

100 parts by mass of the (meth) acrylic acid ester copolymer obtained as described above, 3 parts by mass of a photopolymerization initiator (manufactured by DKSH, product name "ESACURE KIP 150"), and a bird as a cross-linking agent (B). 1 part by mass of methylolpropane-modified tolylene diisocyanate (manufactured by Toyo Ink Co., Ltd., product name "BHS-8515") was mixed in a solvent to obtain a coating solution of the pressure-sensitive adhesive composition.

A peeling-treated surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET38131", thickness: 38 μm) obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent from the coating solution of the obtained pressure-sensitive adhesive composition. Was coated with a knife coater and then treated at 100 ° C. for 1 minute to form an outermost layer having a thickness of 20 μm.

(4) Fabrication of Semiconductor Processing Sheet The release sheet as a process film attached to the intermediate layer of the laminate obtained in the step (2) is peeled off, and the exposed surface of the intermediate layer and the step (3) By laminating the outermost layer of the obtained laminate with the surface opposite to the surface on the release sheet side, the release sheet, the outermost layer, the intermediate layer, and the base material are laminated in this order, that is, the outermost layer. A semiconductor processing sheet was obtained in which the surface opposite to the intermediate layer was protected by a release sheet.

[Example 2]
A semiconductor processing sheet was produced in the same manner as in Example 1 except that the thickness of the outermost layer was changed to 5 μm.

[Example 3]
As an acrylic copolymer for a polymer into which an energy ray-curable group has been introduced, 74 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate. Using an acrylic copolymer copolymerized with 1 part by mass of acrylic acid, 80 mol (80 mol%) of MOI is added per 100 mol of 2-hydroxyethyl acrylate unit of the acrylic copolymer. A sheet for semiconductor processing was prepared in the same manner as in Example 1 except that 16.1 g of MOI was used per 100 g of the acrylic copolymer.

[Example 4]
As an acrylic copolymer for a polymer into which an energy ray-curable group has been introduced, 69 parts by mass of n-butyl acrylate, 10 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate are used. A sheet for semiconductor processing was produced in the same manner as in Example 1 except that an acrylic copolymer obtained by copolymerizing 1 part by mass of acrylic acid was used.

[Example 5]
As an acrylic copolymer for a polymer in which the thickness of the outermost layer is changed to 5 μm and an energy ray-curable group is introduced, 74 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of methyl methacrylate Using an acrylic copolymer obtained by copolymerizing 15 parts by mass of 2-hydroxyethyl acrylate and 1 part by mass of acrylate, 80 parts per 100 mol of 2-hydroxyethyl acrylate unit of the acrylic copolymer is used. A sheet for semiconductor processing was prepared in the same manner as in Example 1 except that 16.1 g of MOI was used per 100 g of the acrylic copolymer so that mol (80 mol%) of MOI was added.

[Example 6]
As an acrylic copolymer for a polymer into which an energy ray-curable group has been introduced, 79 parts by mass of n-butyl acrylate, 20 parts by mass of 2-hydroxyethyl acrylate, and 1 part by mass of acrylic acid are used together. A sheet for semiconductor processing was produced in the same manner as in Example 1 except that the polymerized acrylic copolymer was used.

[Comparative Example 1]
Example 1 except that an acrylic copolymer obtained by copolymerizing 85 parts by mass of n-butyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate is used as the acrylic copolymer for the intermediate layer. A sheet for semiconductor processing was produced in the same manner as in the above.

[Comparative Example 2]
As an acrylic copolymer for a polymer into which an energy ray-curable group has been introduced, 70 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate are used. A sheet for semiconductor processing was produced in the same manner as in Example 1 except that the copolymerized acrylic copolymer was used.

[Comparative Example 3]
90 parts by mass of n-butyl acrylate and 10 parts by mass of acrylic acid were copolymerized to obtain a first acrylic copolymer.

Further, 62 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were copolymerized to obtain a second acrylic copolymer. Further, the second acrylic copolymer was reacted with 2-methacryloyloxyethyl isocyanate (MOI) to obtain a polymer in which an energy ray-curable group (methacryloyl group) was introduced into the side chain. At this time, both so that the MOI is 29.9 g per 100 g of the second acrylic copolymer (80 mol (80 mol%) per 100 mol of 2-hydroxyethyl acrylate unit of the acrylic copolymer). Was reacted.

100 parts by mass of the obtained first acrylic copolymer, 67 parts by mass of the obtained polymer having an energy ray-curable group introduced into the side chain, and a tolylene diisocyanate (TDI) -based cross-linking agent (Toyo Ink). A coating solution for an intermediate layer is prepared by mixing 2.79 parts by mass of BHS8515) manufactured by the same company in a solvent, and a sheet for semiconductor processing is prepared in the same manner as in Example 1 except that the coating solution is used. did. The semiconductor processing sheet thus produced is irradiated with energy rays to cure the intermediate layer together with the outermost layer.

Here, the above-mentioned weight average molecular weight (Mw) is a standard polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) (GPC measurement).

Table 1 shows the composition of the intermediate layer and the outermost layer, the thickness of each of the intermediate layer and the outermost layer, and the combined thickness of the intermediate layer and the outermost layer in each Example / Comparative Example. Details of the abbreviations shown in Table 1 are as follows. Further, in the column of the composition of the outermost layer, the numerical values described in the second row represent the amount (parts by mass) of the material described in the first row, respectively.
2-EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate MOI: 2-methacryloyloxyethyl isocyanate AA: BA acrylate BA: n-butyl acrylate

[Test Example 1] (Measurement of air width and evaluation of embedding property)
As a wafer with protrusions, a silicon wafer provided with a cylindrical structure made of an epoxy resin having a height of 25 μm, a diameter of 30 μm, and a pitch of 50 μm was prepared. A semiconductor processing sheet produced in Examples or Comparative Examples was applied to this silicon wafer using a laminator (lintec, RAD-3510F / 12) at a pasting speed of 10 mm / s, a wafer protrusion amount of 20 μm, and a roller pressure. It was attached under the condition of 0.1 MPa. At this time, the surface of the silicon wafer provided with the protrusions and the surface of the outermost layer exposed by peeling the release sheet from the semiconductor processing sheet were attached.

Then, using an optical microscope, the air width on the outer circumference of the protrusion was measured 1 hour and 24 hours after the application. Here, the air width is a value (μm) obtained by subtracting the diameter of the protrusion from the diameter of the circular void in a plan view generated around the protrusion. Table 1 shows the measured values. When the air width was 10 μm or more, it was described as “completely floating”.

Furthermore, the air width after 24 hours was measured, and the implantability was evaluated according to the following criteria. The results are shown in Table 1.
S: The air width after 24 hours is 5 μm or less.
A: The air width after 24 hours exceeds 5 μm, but it is not “completely floating”.
B: It is "completely floating" after 24 hours.

[Test Example 2] (Measurement of loss tangent of intermediate layer)
A release sheet (manufactured by Lintec Corporation, SP-PET381031, thickness 38 μm) having a silicone-based release agent layer formed on one side of a polyethylene terephthalate film was prepared. The coating solution for the intermediate layer prepared in Examples and Comparative Examples was applied on the peeling surface of the above peeling sheet with a knife coater. The obtained coating film was allowed to elapse in an environment of 100 ° C. for 1 minute to dry the coating film, and a 40 μm-thick test intermediate layer formed from each coating composition and a release sheet were attached. I prepared multiple items that were combined.

These test intermediate layers were laminated until the thickness became 800 μm, and the obtained laminate of the intermediate layers was punched into a circle having a diameter of 10 mm to obtain a sample for measuring the viscoelasticity of the intermediate layers. Using a viscoelasticity measuring device (ARES, manufactured by TA Instruments), a strain with a frequency of 1 Hz was applied to the above sample, and a storage elastic modulus G'and a loss elastic modulus G'at -50 to 150 ° C. 'Is measured, and the loss tangent tan δ at 23 ° C. was calculated from those values. The results are shown in Table 1.

[Test Example 3] (Measurement of adhesive strength of the outermost layer before irradiation with energy rays)
A semiconductor processing sheet produced in Examples or Comparative Examples was cut into a width of 25 mm on a silicon mirror wafer, and a laminator (lintec, RAD-3510F / 12) was used to attach a sheet at a sticking speed of 10 mm / s. , The wafer was attached under the conditions of a wafer protrusion amount of 20 μm and a roller pressure of 0.1 MPa. At this time, one surface of the silicon mirror wafer and the surface of the outermost layer exposed by peeling the release sheet from the semiconductor processing sheet were attached. This was left to stand in an atmosphere of 23 ° C. and 50% RH for 20 minutes.

After that, except for the above conditions, a silicon mirror wafer was used to peel the sheet at a peeling angle of 180 ° and a peeling speed of 300 mm / min using a universal tensile tester (Tencilon UTM-4-100 manufactured by Orientec) in accordance with JIS Z0237. The adhesive strength was measured, and this was taken as the adhesive strength (mN / 25 mm) before irradiation with energy rays. The measurement results are shown in Table 1.

[Test Example 4] (Measurement of peeling force of outermost layer and evaluation of peeling property)
Similar to Test Example 1, the outermost surface of the exposed outermost layer was attached to the wafer with protrusions by peeling the release sheet from the semiconductor processing sheet. Then, after leaving it in an atmosphere of 23 ° C. and 50% RH for 20 minutes, ultraviolet rays (UV) were emitted from the substrate side of the sheet in a nitrogen atmosphere using an ultraviolet irradiation device (manufactured by Lintec Corporation, RAD-2000 m / 12). Irradiation (irradiance 230 mW / cm ² , light intensity 190 mJ / cm ² ) was performed.

Regarding the sheet after irradiation with ultraviolet rays, the adhesive force was measured in the same manner as in Test Example 3 except that the sheet cut to a width of 8 mm was used, and the peeling force after irradiation with energy rays (mN / 8 mm) was obtained. The measurement results are shown in Table 1.

In addition, the number of defects in the 10 resin protrusions on the wafer surface after peeling was counted using an optical microscope. The results are shown in Table 1.

Furthermore, the peelability was evaluated according to the following criteria according to the peeling force and the number of defects of the resin protrusions. The results are shown in Table 1.
S: The peeling force is 300 mN / 8 mm or less, and the number of defects is 0.
A: The peeling force exceeds 300 mN / 8 mm, and the number of defects is 0.
B: The number of defects is 1 or more.

Regarding the semiconductor processing sheets of Comparative Examples 1 and 2, since the result of Test Example 1 was poor, the test for practicality evaluation was stopped at that time, and Test Example 4 was not performed.

[Test Example 5] (Measurement of storage elastic modulus after irradiation with energy rays of the outermost layer)
The most prepared in Examples and Comparative Examples on the peeling surface of a peeling sheet (Lintec Corporation: SP-PET38131) in which a silicone-based release agent layer is formed on one side of a 38 μm-thick polyethylene terephthalate base film. The pressure-sensitive adhesive composition for the outer layer was applied with a comma coater. The coating film was dried by allowing this to elapse in an environment of 100 ° C. for 1 minute, and the outermost layer for testing having a thickness of 40 μm formed from each coating composition and the release sheet were bonded to each other. I prepared more than one. By laminating the outermost layers for these tests, a laminated body of the outermost layers having a thickness of 200 μm was obtained.

^{This laminated body was irradiated with ultraviolet rays (irradiance 230 mW / cm 2} and light intensity 600 mJ / cm ² three times) using an ultraviolet irradiation device (RAD-2000 m / 12 manufactured by Lintec Corporation) to prepare a measurement sample. ..

For this measurement sample, the elastic modulus E'at 23 ° C. was measured at a frequency of 11 Hz using a dynamic viscoelastic automatic measuring device (Vibron DDV-01FP manufactured by Orientec Co., Ltd.), and the storage elastic modulus after energy ray irradiation ( MPa). The results are shown in Table 1.

[Test Example 6] (Evaluation of solvent resistance)
In the semiconductor processing sheets manufactured in Examples and Comparative Examples, the surface of the outermost layer exposed by peeling the release sheet and the mirror surface of a silicon wafer (diameter 8 inches, thickness 50 μm) with one side mirror-polished are attached. did. The application was performed in an environment of 23 ° C. at an application pressure of 0.3 MPa and an application speed of 5 mm / sec. Further, a ring frame (RF) was attached to the outer peripheral portion of the sheet under the same conditions.

Next, the silicon wafer attached to the semiconductor processing sheet is immersed in p-menthane (solubility parameter: 7.2) as a solvent at 23 ° C. for 5 minutes, and then between the silicon wafer and the semiconductor processing sheet. Infiltration of the solvent and the appearance of the wafer were observed. "No problem" if the solvent does not penetrate between the silicon wafer and the semiconductor processing sheet and there is no change in appearance such as peeling of the outermost layer or wrinkling of the base material. , Otherwise, the condition was recorded. The results are shown in Table 1.

As is clear from Table 1, the semiconductor processing sheet of the example has good embedding property of protrusions and is excellent in peelability of an adherend having protrusions.

The semiconductor processing sheet according to the present invention is suitably used as a debond sheet for a semiconductor wafer or a semiconductor chip having protrusions, particularly resin protrusions.

1 ... Semiconductor processing sheet 2 ... Base material 3 ... Intermediate layer 4 ... Outermost layer 20W ... Wafer with protrusions 20C ... Chip 21 ... Wafer 22 ... Hard support 23 ... Projections 24a, 24b ... Ring frame 25 ... Cleaning device 26 … Pickup sheet

Claims (7)

A semiconductor processing sheet comprising a base material, an intermediate layer laminated on one surface side of the base material, and an outermost layer laminated on the side opposite to the base material of the intermediate layer.
The outermost layer is made of an energy ray-curable pressure-sensitive adhesive.
The loss tangent of the intermediate layer at 23 ° C. is 0.4 or more.
The adhesive force of the semiconductor processing sheet to the silicon mirror wafer before irradiation with energy rays is 12000 mN / 25 mm or more.
The intermediate layer is made of a material whose rheological properties do not substantially change when irradiated with energy rays.
The material is a non-energy ray curable material and
A semiconductor processing sheet, which is used in a semiconductor wafer processing method including a step of bringing the semiconductor processing sheet into contact with an organic solvent in a state of being attached to the semiconductor wafer. The semiconductor processing sheet according to claim 1 , wherein the outermost layer has a thickness of 1 to 10 μm. The semiconductor processing sheet according to claim 1 or 2 , wherein the outermost layer contains an acrylic polymer containing methyl methacrylate as a monomer component. The semiconductor processing sheet according to any one of claims 1 to 3 , wherein the outermost layer contains an acrylic polymer having an energy ray-curable group introduced therein. The semiconductor processing sheet according to any one of claims 1 to 4 , wherein the storage elastic modulus at 23 ° C. after irradiation of the outermost layer with energy rays is 270 MPa or less. The semiconductor processing sheet according to any one of claims 1 to 5 , wherein the processing sheet is a semiconductor wafer or a semiconductor chip having protrusions. The semiconductor processing sheet according to any one of claims 1 to 6 , wherein the solubility parameter of the organic solvent is 10 or less.

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