JP7162612B2 - Work processing sheet and manufacturing method for processed work - Google Patents

Description

TECHNICAL FIELD The present invention relates to a work processing sheet that can be suitably used for dicing, and a method for manufacturing a processed work using the work processing sheet.

Semiconductor wafers such as silicon and gallium arsenide and various packages (hereinafter collectively referred to as "cutting objects") are manufactured in a large diameter state, and these are element pieces (hereinafter referred to as " After being separated (diced) into individual pieces (picked up), they are moved to the next step, the mounting step. At this time, the object to be cut such as a semiconductor wafer is subjected to each step of dicing, washing, drying, expanding, picking up and mounting while being attached to a work processing sheet having a base material and an adhesive layer. be.

In the dicing process described above, frictional heat generated between the rotating dicing blade, the object to be cut, and the work processing sheet heats the dicing blade, the object to be cut, and the work processing sheet. In addition, in the dicing process, cut pieces are generated from the object to be cut or the work processing sheet, and may adhere to the chip.

Therefore, when performing the dicing process, generally, running water is supplied to the cut portion to cool the dicing blade and the like, and the generated chips are removed from the chip.

In Patent Document 1, for the purpose of promoting the removal of cut pieces by running water, the surface of the adhesive layer opposite to the base material before ultraviolet irradiation has a contact angle of 82° to 114° with respect to pure water. and a contact angle to methylene iodide of 44° to 64°, and a probe tack test peak value of 294 to 578 kPa in the pressure-sensitive adhesive layer before ultraviolet irradiation. .

Patent No. 5019657

However, when performing a dicing process using a conventional work processing sheet as disclosed in Patent Document 1, the adhesive derived from the adhesive layer of the work processing sheet is sufficiently removed from the work after processing. couldn't.

In general, when the chip is separated from the workpiece processing sheet in the pick-up process, it is required that the chip can be separated without requiring excessive force, so that problems such as breakage of the chip do not occur. .

The present invention has been made in view of such actual circumstances, and the adhesive derived from the adhesive layer attached to the work after processing can be removed satisfactorily by running water, and the work after processing can be removed. It is an object of the present invention to provide a work processing sheet that can be separated satisfactorily, and a method for manufacturing a processed work using the work processing sheet.

In order to achieve the above object, firstly, the present invention provides a work processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the adhesive layer has an active It is composed of an energy ray-curable adhesive, and the oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the surface of the adhesive layer opposite to the base material is 28 atomic % or less, and the Among the positions in the pressure-sensitive adhesive layer, the oxygen atomic ratio R ₁₀₀ measured by X-ray photoelectron spectroscopy at a position at a depth of 100 nm from the surface of the pressure-sensitive adhesive layer opposite to the base material is 20 atomic % or more, Provided is a work processing sheet characterized by having a content of 29 atomic % or less (Invention 1).

In the work processing sheet according to the above invention (Invention 1), the oxygen atomic ratio measured by X-ray photoelectron spectroscopy on the surface of the adhesive layer opposite to the base material (hereinafter sometimes referred to as "adhesive surface") When R ₀ is 28 atomic % or less, the adhesive surface has a suitable degree of hydrophobicity, and the workpiece after processing can be easily separated. In addition, the oxygen atomic ratio R ₁₀₀ measured by X-ray photoelectron spectroscopy at a position at a depth of 100 nm from the adhesive surface among the positions in the adhesive layer is 20 atomic % or more and 29 atomic % or less, so that after processing The surface of the adhesive adhering to the work has moderate hydrophilicity, and the adhesive adhering to the work after processing can be removed satisfactorily with running water.

In the above invention (Invention 1), the value of the oxygen atomic ratio R ₀ is greater than the value of the oxygen atomic ratio R ₁₀₀ , and the following formula (1)
Reduction rate of oxygen atomic ratio (%)={(oxygen atomic ratio R ₀ −oxygen atomic ratio R ₁₀₀ )/oxygen atomic ratio R ₀ }×100 (1)
is preferably 0% or more and 15% or less (Invention 2).

In the above inventions (Inventions 1 and 2), the active energy ray-curable adhesive is preferably an adhesive formed from an adhesive composition containing an active energy ray-polymerizable branched polymer (Invention 3). .

In the above inventions (Inventions 1 to 3), the pressure-sensitive adhesive composition is obtained by reacting an acrylic copolymer having a functional group-containing monomer unit and an unsaturated group-containing compound having a functional group that binds to the functional group. The acrylic copolymer contains methyl acrylate, 2-methoxyethyl (meth)acrylate, (meth)acrylate, and (meth)acrylate as monomer units constituting the polymer. ) preferably contains at least one selected from ethyl carbitol acrylate and methoxyethylene glycol (meth)acrylate (Invention 4).

In the above inventions (inventions 1 to 4), it is preferably a dicing sheet (invention 5).

The second aspect of the present invention is a bonding step of bonding a surface of the work processing sheet (inventions 1 to 5) on the side opposite to the base material and a work, and A processing step of obtaining a processed work laminated on the work processing sheet by processing the work on the sheet, and irradiating the adhesive layer with an active energy ray to the adhesive layer. and a separation step of separating the processed work from the work processing sheet after the active energy ray irradiation. (Invention 6).

The work processing sheet according to the present invention can satisfactorily remove the adhesive derived from the adhesive layer adhering to the processed work by running water, and can also satisfactorily separate the processed work. . Moreover, according to the method for manufacturing a machined work according to the present invention, it is possible to efficiently produce a machined work.

Embodiments of the present invention will be described below.
[Work processing sheet]
A work processing sheet according to this embodiment includes a substrate and an adhesive layer laminated on one side of the substrate.

1. Physical properties of work processing sheet In the work processing sheet according to the present embodiment, the oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the surface (adhesive surface) of the adhesive layer opposite to the base material is 28. atomic % or less. When the oxygen atomic ratio R ₀ is 28 atomic % or less, the adhesive surface has an appropriate degree of hydrophobicity, and an excessive increase in the adhesive strength of the work processing sheet to the work after processing is suppressed. . As a result, it is possible to satisfactorily separate the work after processing from the work processing sheet. In particular, when a silicon wafer is used as a workpiece, there are relatively many hydrophilic groups on the surface of the silicon wafer, and an adhesive surface having moderate hydrophobicity comes into contact with this surface. As a result, the workpiece after processing can be easily separated. The details of the method for measuring the oxygen atomic ratio R ₀ described above are as described in the test examples described later.

If the above oxygen atomic ratio R ₀ exceeds 28 atomic %, the adhesive surface will have relatively high hydrophilicity, and the adhesion of the work processing sheet to the work after processing will be excessively high. In this case, an excessive force is required to separate the processed work from the work processing sheet, and there is a possibility that trouble such as breakage of the processed work may occur. From the viewpoint of avoiding such problems, the oxygen atomic ratio R ₀ is preferably 27 atomic % or less.

The oxygen atomic ratio R ₀ is preferably 20 atomic % or more, and more preferably 22 atomic % or more. When the oxygen atomic ratio R ₀ is 20 atomic % or more, the hydrophilicity of the adhesive surface becomes moderate, and the work processing sheet easily exhibits good adhesion to the work. As a result, it is possible to effectively suppress unintentional peeling of workpieces before or after processing when processing workpieces or when conveying workpieces or processed workpieces in a stacked state on a work processing sheet. becomes.

In the work processing sheet according to the present embodiment, the oxygen atomic ratio R ₁₀₀ measured by X-ray photoelectron spectroscopy at a position in the adhesive layer at a depth of 100 nm from the adhesive surface is 20 atomic % or more and 29 atoms. % or less. As a result, the pressure-sensitive adhesive inside the pressure-sensitive adhesive layer has appropriate hydrophilicity.

Generally, when dicing using a dicing blade, the rotating dicing blade is applied to the object to be cut while supplying running water to the cut portion to cut the object to be cut. At this time, the rotating dicing blade may contact not only the object to be cut but also the adhesive layer. At such a contact portion, the adhesive layer is cut and the adhesive constituting the adhesive layer is rolled up by the dicing blade, resulting in the formation of small pieces of the adhesive. The small pieces adhere to the object to be cut or the formed chip, adversely affecting subsequent handling of the chip, or causing deterioration in the quality of the chip or the product on which the chip is mounted. Here, since the small pieces of the adhesive are formed as described above, most of the small pieces exist inside the adhesive layer when the adhesive layer is formed.

In the work processing sheet according to the present embodiment, as described above, the adhesive inside the adhesive layer has moderate hydrophilicity. occurs, and even if the small piece adheres to the workpiece (chip or the like) after processing, the surface of the small piece has moderate hydrophilicity. Therefore, according to the work processing sheet according to the present embodiment, the adhesive adhering to the work can be removed satisfactorily from the processed work by running water supplied during processing.

On the other hand, when the oxygen atomic ratio R ₁₀₀ is less than 20 atomic %, the adhesive inside the adhesive layer does not have sufficient affinity for water, and small pieces of the adhesive are removed from the work after processing. cannot be sufficiently removed. From the viewpoint of avoiding such problems, the oxygen atomic ratio R ₁₀₀ described above is preferably 21 atomic % or more.

In addition, when the above-mentioned oxygen atomic ratio R ₁₀₀ exceeds 29 atomic %, the adhesive inside the adhesive layer exhibits excessive affinity for water. have a high affinity for As a result, the intrusion of water cannot be suppressed, and chip flying or chipping occurs during dicing. From the viewpoint of avoiding such problems, the oxygen atomic ratio R ₁₀₀ described above is preferably 27 atomic % or less. The details of the method for measuring the oxygen atomic ratio R ₁₀₀ are as described in the test examples described later.

In the work processing sheet according to the present embodiment, the value of the oxygen atomic ratio R ₁₀₀ is greater than the value of the oxygen atomic ratio R ₀ as long as the oxygen atomic ratio R ₀ and the oxygen atomic ratio R ₁₀₀ are within the ranges described above. Alternatively, the value of the oxygen atomic ratio _R0 may be greater than the value of the oxygen atomic ratio _R100 . Alternatively, the oxygen atomic ratio _R0 and the oxygen atomic ratio _R100 may have the same value. When the value of the oxygen atomic ratio R ₀ is greater than the value of the oxygen atomic ratio R ₁₀₀ , the following formula (1)
Reduction rate of oxygen atomic ratio (%)={(oxygen atomic ratio R ₀ −oxygen atomic ratio R ₁₀₀ )/oxygen atomic ratio R ₀ }×100 (1)
is preferably 0% or more, particularly preferably 1% or more, further preferably 2% or more. Moreover, the reduction rate is preferably 15% or less, particularly preferably 12% or less, and further preferably 10% or less. When the reduction rate of the oxygen atomic ratio is within the range described above, it becomes easy to achieve both good removal of the adhesive by running water and good separation of the processed work from the work processing sheet. .

In the work processing sheet according to the present embodiment, the adhesive force of the work processing sheet to the silicon wafer is preferably 1000 mN/25 mm or more, particularly preferably 1200 mN/25 mm or more, further preferably 1500 mN/25 mm or more. is preferably The adhesive strength here refers to the adhesive strength in a state where the work processing sheet is not irradiated with active energy rays and the adhesive layer is not cured. Further, throughout the present specification, the "adhesive force" described without mentioning the presence or absence of active energy ray irradiation does not irradiate the work processing sheet with the active energy ray, and the adhesive layer It refers to the adhesive strength in the state where the curing has not occurred. When the above-mentioned adhesive force is 1000 mN / 25 mm or more, it becomes easy to hold the work to be processed on the work processing sheet well, and the work or the work after processing can be easily held on the work processing sheet. It is possible to satisfactorily suppress peeling of the work before or after processing when conveying the work in a stacked state. In particular, when the workpiece after machining is a chip, it is possible to satisfactorily prevent the chip from scattering from the workpiece machining sheet.

The adhesive force of the work processing sheet to the silicon wafer is preferably 5000 mN/25 mm or less, particularly preferably 4500 mN/25 mm or less, and more preferably 3000 mN/25 mm or less. When the adhesive strength is 5000 mN/25 mm or less, the adhesive strength after irradiation with active energy rays can be easily adjusted within the range described below. The details of the method for measuring the adhesive force of the work processing sheet to the silicon wafer are as described in the test examples described later.

In addition, in the work processing sheet according to the present embodiment, it is preferable that the adhesive force of the work processing sheet to the silicon wafer after the work processing sheet is irradiated with active energy rays is 65 mN/25 mm or less. When the adhesive force is 65 mN / 25 mm or less, it is easier to separate the processed work from the work processing sheet by irradiating the work processing sheet with active energy rays after the work processing is completed. Become.

2. Components of Work Processing Sheet (1) Base Material In the work processing sheet according to the present embodiment, the base material exhibits a desired function in the process of using the work processing sheet, and preferably cures the pressure-sensitive adhesive layer. It is not particularly limited as long as it exhibits good transparency to the active energy ray irradiated for the purpose.

For example, the substrate is preferably a resin film mainly composed of a resin-based material, and specific examples thereof include ethylene-vinyl acetate copolymer film; ethylene-(meth)acrylic acid copolymer film; Ethylene-based copolymer films such as ethylene-methyl (meth)acrylate copolymer films and other ethylene-(meth)acrylate copolymer films; polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene Polyolefin films such as films, ethylene-norbornene copolymer films, norbornene resin films; polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films; polyethylene terephthalate films, polybutylene terephthalate films, polyethylene naphthalate (meth)acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; Examples of polyethylene films include low density polyethylene (LDPE) films, linear low density polyethylene (LLDPE) films, high density polyethylene (HDPE) films, and the like. Modified films such as these crosslinked films and ionomer films are also used. Further, the base material may be a laminated film formed by laminating a plurality of films described above. In this laminated film, the materials constituting each layer may be of the same type or of different types. As the substrate, among the above films, it is preferable to use an ethylene-methyl methacrylate copolymer film from the viewpoint of excellent flexibility. In addition, "(meth)acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same is true for other similar terms.

The substrate may contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. Although the content of these additives is not particularly limited, it is preferably within a range in which the base material exhibits the desired functions.

The surface of the base material on which the pressure-sensitive adhesive layer is to be laminated may be subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, etc., in order to enhance adhesion with the pressure-sensitive adhesive layer.

The thickness of the base material can be appropriately set according to the method in which the work processing sheet is used, but it is usually preferably 20 μm or more, particularly preferably 25 μm or more. Also, the thickness is usually preferably 450 μm or less, particularly preferably 300 μm or less.

(2) Adhesive layer In the work processing sheet according to the present embodiment, the adhesive layer is composed of an active energy ray-curable adhesive, and can exhibit a desired adhesive strength, and the above-mentioned oxygen atomic ratio There are no particular limitations as long as R ₀ and oxygen atomic ratio R ₁₀₀ are within the ranges described above.

In the work processing sheet according to the present embodiment, the adhesive layer is composed of an active energy ray-curable adhesive, so that the work after processing attached to the adhesive surface of the adhesive layer and the adhesive surface. When separating, the adhesive layer can be cured by irradiation with active energy rays to reduce the adhesive force of the work processing sheet to the work after processing. This makes it easy to separate the adhesive surface of the adhesive layer from the work after processing.

The pressure-sensitive adhesive layer in the present embodiment may be formed from a pressure-sensitive adhesive composition containing an active energy ray-curable polymer, or an active energy ray non-curable polymer (active energy ray-curable polymer having no active energy ray-curable group) and a monomer and/or oligomer having at least one active energy ray-curable group.

First, the case where the pressure-sensitive adhesive layer in this embodiment is formed from a pressure-sensitive adhesive composition containing an active energy ray-curable polymer will be described below.

The active energy ray-curable polymer is a (meth)acrylic acid ester (co)polymer (A) (hereinafter referred to as It may be referred to as "active energy ray-curable polymer (A)"). This active energy ray-curable polymer (A) comprises an acrylic copolymer (a1) having a functional group-containing monomer unit and an unsaturated group-containing compound (a2) having a functional group that binds to the functional group. It is preferably obtained by reacting.

The acrylic copolymer (a1) contains, as a monomer unit constituting the polymer, a monomer for adjusting the hydrophilicity of the acrylic copolymer (a1) (hereinafter sometimes referred to as a "hydrophilicity-adjusting monomer". ), and particularly specific examples thereof include methyl acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate (ethoxyethoxyethyl (meth)acrylate) and (meth)acrylate. ) preferably contains at least one selected from methoxyethylene glycol acrylate.

In the pressure-sensitive adhesive sheet according to the present embodiment, the use of the hydrophilicity-adjusting monomer described above for the acrylic copolymer (a1) makes it easy to adjust the oxygen atomic ratio R ₁₀₀ within the range described above. The reason for this is that many of the hydrophilicity-adjusting monomers described above have a relatively large number of oxygen atoms, and by using the acrylic copolymer (a1) composed of these monomers, the pressure-sensitive adhesive layer can be This is probably because the absolute amount of oxygen atoms also increases, making it easier to adjust the oxygen atom ratio _R100 within the above range. However, it is not limited only to this reason.

From the viewpoint that the oxygen atomic ratio R ₁₀₀ described above can be easily adjusted to the range described above, the acrylic copolymer (a1) includes methyl acrylate, methyl acrylate, It preferably contains at least one of 2-methoxyethyl acrylate and methoxyethylene glycol acrylate.

When the acrylic copolymer (a1) contains methyl acrylate as a monomer unit constituting the polymer, the content of methyl acrylate is preferably 10% by mass or more, particularly 20% by mass or more. is preferred, and more preferably 30% by mass or more. Moreover, the content of methyl acrylate is preferably 85% by mass or less. These contents make it easier to adjust the oxygen atomic ratio _R100 in the pressure-sensitive adhesive layer to be formed within the range described above. In addition, in this specification, the content (% by mass) of methyl acrylate mentioned above means the content with respect to all the monomers constituting the acrylic copolymer (a1). In addition, the content (% by mass) of other monomers described later also means the content relative to all the monomers constituting the acrylic copolymer (a1).

Further, when the acrylic copolymer (a1) contains 2-methoxyethyl acrylate as a monomer unit constituting the polymer, the content of 2-methoxyethyl acrylate is preferably 10% by mass or more. In particular, it is preferably 20% by mass or more, more preferably 30% by mass or more. The content of 2-methoxyethyl acrylate is preferably 85% by mass or less, particularly preferably 80% by mass or less, further preferably 70% by mass or less. These contents make it easier to adjust the oxygen atomic ratio _R100 in the pressure-sensitive adhesive layer to be formed within the range described above.

Further, when the acrylic copolymer (a1) contains both methyl acrylate and 2-methoxyethyl acrylate as monomer units constituting the polymer, the content of methyl acrylate and 2-methoxyethyl acrylate The total value is preferably 10% by mass or more, particularly preferably 30% by mass or more, and further preferably 50% by mass or more. Moreover, the above total value is preferably 90% by mass or less, and particularly preferably 85% by mass or less. When the total value is within these ranges, it becomes easier to adjust the oxygen atomic ratio R ₁₀₀ in the pressure-sensitive adhesive layer to be formed within the range described above.

Furthermore, when the acrylic copolymer (a1) contains methoxyethylene glycol acrylate as a monomer unit constituting the polymer, the content of methoxyethylene glycol acrylate is preferably 10% by mass or more, particularly 30% by mass. % or more is preferable. Also, the content of methoxyethylene glycol acrylate is preferably 90% by mass or less, particularly preferably 85% by mass or less. These contents make it easier to adjust the oxygen atomic ratio _R100 in the pressure-sensitive adhesive layer to be formed within the range described above.

The acrylic copolymer (a1) preferably contains structural units derived from functional group-containing monomers and structural units derived from (meth)acrylic acid ester monomers or derivatives thereof, in addition to the hydrophilicity-adjusting monomers described above. .

The functional group-containing monomer as a structural unit of the acrylic copolymer (a1) has a polymerizable double bond and a functional group such as a hydroxy group, a carboxyl group, an amino group, a substituted amino group, an epoxy group, etc. in the molecule. Among these, it is preferable to contain at least one of a hydroxyl group-containing monomer, an amino group-containing monomer and a substituted amino group-containing monomer.

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like can be mentioned, and these can be used alone or in combination of two or more.

Examples of the amino group-containing monomer or substituted amino group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used alone or in combination of two or more.

Examples of carboxy group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. You may use it in combination of 2 or more types. However, the acrylic copolymer (a1) preferably does not contain a carboxy group-containing monomer. Since the acrylic copolymer (a1) does not contain a carboxy group-containing monomer, it becomes easier to adjust the water contact angle.

The acrylic copolymer (a1) preferably contains 1% by mass or more, particularly preferably 5% by mass or more, further preferably 10% by mass or more of the structural unit derived from the functional group-containing monomer. preferably. The acrylic copolymer (a1) preferably contains 35% by mass or less, more preferably 30% by mass or less, of structural units derived from the functional group-containing monomer.

Examples of the (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1) include (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 20 carbon atoms, and, for example, an alicyclic A monomer having a structure (alicyclic structure-containing monomer) is preferably used.

Examples of (meth)acrylic acid alkyl esters include (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms, such as methyl methacrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-Butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and the like are preferably used. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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

Furthermore, the acrylic copolymer (a1) preferably contains 50% by mass or more, particularly preferably 60% by mass or more, of structural units derived from (meth)acrylic acid ester monomers or derivatives thereof. Furthermore, it is preferable to contain 70 mass % or more. Further, the acrylic copolymer (a1) preferably contains 99% by mass or less, particularly 95% by mass or less, of structural units derived from (meth)acrylic acid ester monomers or derivatives thereof. It is preferably contained in an amount of 90% by mass or less.

The acrylic copolymer (a1) can be preferably obtained by copolymerizing the aforementioned hydrophilicity-adjusting monomer, functional group-containing monomer, and (meth)acrylic acid ester monomer or derivative thereof in a conventional manner. However, in addition to these monomers, dimethylacrylamide, vinyl formate, vinyl acetate, styrene, etc. may be copolymerized.

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

The functional group of the unsaturated group-containing compound (a2) can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group possessed by the acrylic copolymer (a1) is a hydroxy group, an amino group or a substituted amino group, the functional group possessed by the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group. When the functional group possessed by the system copolymer (a1) is an epoxy group, the functional group possessed by the unsaturated group-containing compound (a2) is preferably an amino group, a carboxyl group or an aziridinyl group.

The unsaturated group-containing compound (a2) contains at least 1, preferably 1 to 6, more preferably 1 to 4 active energy ray-polymerizable carbon-carbon double bonds per molecule. is Specific examples of such unsaturated group-containing compounds (a2) include, for example, 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-( Bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound and hydroxyethyl (meth)acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, and (meth) acrylic Acryloyl monoisocyanate compound obtained by reaction with hydroxyethyl acid; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2 -isopropenyl-2-oxazoline and the like.

The unsaturated group-containing compound (a2) is preferably 50 mol% or more, particularly preferably 60 mol% or more, more preferably 60 mol% or more, more preferably It is used in a proportion of 70 mol % or more. In addition, the unsaturated group-containing compound (a2) is preferably 95 mol% or less, particularly preferably 93 mol% or less, based on the number of moles of the functional group-containing monomer in the acrylic copolymer (a1). It is preferably used in a proportion of 90 mol % or less.

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) Depending on the combination, reaction temperature, pressure, solvent, time, the presence or absence of a catalyst, and the type of catalyst can be appropriately selected. As a result, the functional groups present in the acrylic copolymer (a1) react with the functional groups in the unsaturated group-containing compound (a2), and the unsaturated groups in the acrylic copolymer (a1) It is introduced into the side chain to obtain an active energy ray-curable polymer (A).

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

Even when the pressure-sensitive adhesive composition in the present embodiment contains an active energy ray-curable polymer such as the active energy ray-curable polymer (A), the pressure-sensitive adhesive composition is active energy ray-curable. may further contain monomers and/or oligomers (B) of

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

Examples of such active energy ray-curable monomers and/or oligomers (B) include monofunctional acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, Pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene polyfunctional acrylates such as glycol di(meth)acrylate and dimethyloltricyclodecane di(meth)acrylate; polyester oligo(meth)acrylate; polyurethane oligo(meth)acrylate;

When blending the active energy ray-curable monomer and/or oligomer (B) together with the active energy ray-curable polymer (A), the active energy ray-curable monomer and/or oligomer (B ) is preferably more than 0 parts by mass, particularly preferably 60 parts by mass or more, relative to 100 parts by mass of the active energy ray-curable polymer (A). The content is preferably 250 parts by mass or less, particularly preferably 200 parts by mass or less, relative to 100 parts by mass of the active energy ray-curable polymer (A).

Here, when ultraviolet rays are used as the active energy ray for curing the active energy ray-curable adhesive, the adhesive composition in the present embodiment preferably contains a photopolymerization initiator (C). The use of this photopolymerization initiator (C) can reduce the polymerization curing time and the amount of light irradiation.

Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexylphenyl ketone, benzyldiphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4, 6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2, 2-dimethoxy-1,2-diphenylethan-1-one and the like. These may be used independently and may use 2 or more types together.

The content of the photopolymerization initiator (C) in the adhesive composition is the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and/or oligomer (B) is blended, The total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and/or oligomer (B) (100 parts by mass) is preferably 0.1 parts by mass or more with respect to 100 parts by mass. In particular, it is preferably at least 0.5 parts by mass. In addition, the content is the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and/or oligomer (B) is blended, the active energy ray-curable polymer (A) and It is preferably 10 parts by mass or less, particularly preferably 6 parts by mass or less, per 100 parts by mass of the total amount of active energy ray-curable monomers and/or oligomers (B) (100 parts by mass).

The pressure-sensitive adhesive composition in this embodiment preferably contains an additive (D) for adjusting the oxygen atomic ratio in the pressure-sensitive adhesive layer. Examples of such additives include active energy ray-polymerizable branched polymers, branched polymers, and epoxy resins. From the point of view, it is preferable to use an active energy ray-polymerizable branched polymer.

The active energy ray-polymerizable branched polymer is a type of active energy ray-polymerizable compound, and means a polymer having an active energy ray-polymerizable group and a branched structure. Since the pressure-sensitive adhesive layer in the present embodiment is formed from a pressure-sensitive adhesive composition containing an active energy ray-polymerizable branched polymer, the oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the pressure-sensitive adhesive surface is 28. It becomes easy to adjust to atomic % or less. Reasons for this include, but are not limited to, the following. When forming an adhesive layer using an adhesive composition containing an active energy ray-polymerizable branched polymer, the active energy ray-polymerizable branched polymer is likely to be unevenly distributed on the surface side of the adhesive layer. Therefore, in the formed pressure-sensitive adhesive layer, the content of the active energy ray-polymerizable branched polymer is greater in the portion closer to the surface than in the inside. Here, since the active energy ray-polymerizable branched polymer itself is a component having a relatively small oxygen atom ratio, the pressure-sensitive adhesive surface where the active energy ray-polymerizable branched polymer is present in a larger amount has an oxygen atom content of 28 atomic % or less. It becomes easy to achieve the ratio.

In addition, since the active energy ray-polymerizable branched polymer has an active energy ray-polymerizable group, when the work processing sheet is irradiated with the active energy ray, the active energy ray-polymerizable branched polymers A polymerization reaction can occur between the energy ray-polymerizable branched polymer and a component having an active energy ray-curable group, thereby suppressing migration of the active energy ray-polymerizable branched polymer to the workpiece after processing. At the same time, the pressure-sensitive adhesive layer after irradiation with the active energy ray becomes more hardened, making it easier to effectively separate the work after processing from the work processing sheet.

As described above, the active energy ray-polymerizable branched polymer is a polymer having an active energy ray-polymerizable group and a branched structure. The number of linearly polymerizable groups) is not particularly limited. A method for obtaining such an active energy ray-polymerizable branched polymer includes, for example, a monomer having two or more radically polymerizable double bonds in the molecule, an active hydrogen group and one radically polymerizable double bond. A polymer having a branched structure obtained by polymerizing a monomer having in the molecule and a monomer having one radically polymerizable double bond in the molecule reacts with an active hydrogen group to form a bond It can be obtained by reacting a compound having a possible functional group and at least one radically polymerizable double bond in the molecule. Each of the above three monomers may be (meth)acrylic acid ester or (meth)acrylic acid, and in this case, the active energy ray-polymerizable branched polymer is an acrylic polymer.

The weight average molecular weight of the active energy ray-polymerizable branched polymer is preferably 1,000 or more, particularly preferably 3,000 or more. Also, the weight average molecular weight is preferably 100,000 or less, particularly preferably 30,000 or less. When the weight-average molecular weight is within the range described above, it becomes easy to adjust the oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the adhesive surface to 28 atomic % or less.

The content of the additive (D) in the adhesive composition is 100 parts by mass of the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and/or oligomer (B) is blended, , the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and/or oligomer (B) is 100 parts by mass), preferably 0.05 parts by mass or more, particularly It is preferably 0.1 parts by mass or more. In addition, the content is 100 parts by mass of the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and/or oligomer (B) is blended, the active energy ray-curable polymer ( It is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, relative to the total amount of A) and the active energy ray-curable monomer and/or oligomer (B) (100 parts by mass). . When the content of the additive (D) is within the range described above, it becomes easy to adjust the oxygen atomic ratio in the pressure-sensitive adhesive layer to the desired range.

In addition to the components described above, the pressure-sensitive adhesive composition of the present embodiment may contain other components as appropriate. Other components include, for example, an active energy ray non-curable polymer component or oligomer component (E), a cross-linking agent (F), and the like.

Examples of the active energy ray non-curable polymer component or oligomer component (E) include polyacrylates, polyesters, polyurethanes, polycarbonates, polyolefins, etc., and polymers or polymers having a weight average molecular weight (Mw) of 3000 to 2.5 million. Oligomers are preferred. By incorporating the component (E) into the active energy ray-curable pressure-sensitive adhesive, the adhesiveness and peelability before curing, strength after curing, adhesion to other layers, storage stability, etc. can be improved. The amount of the component (E) to be added is not particularly limited, and is appropriately determined in the range of more than 0 parts by mass and 50 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable polymer (A).

As the cross-linking agent (F), a polyfunctional compound having reactivity with the functional groups of the active energy ray-curable polymer (A) or the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, Reactive phenol resin etc. can be mentioned.

The amount of the cross-linking agent (F) to be blended is preferably 0.01 parts by mass or more, particularly preferably 3 parts by mass or more, relative to 100 parts by mass of the active energy ray-curable polymer (A). The amount of the cross-linking agent (F) to be blended is preferably 20 parts by mass or less, particularly preferably 17 parts by mass or less, per 100 parts by mass of the active energy ray-curable polymer (A).

Next, the pressure-sensitive adhesive layer in the present embodiment is formed from a pressure-sensitive adhesive composition containing an active energy ray non-curable polymer component and a monomer and/or oligomer having at least one active energy ray-curable group. The case where the

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

As the monomer and/or oligomer having at least one or more active energy ray-curable groups, the same monomers and/or oligomers as those for component (B) can be selected. The blending ratio of the active energy ray non-curable polymer component and the monomer and/or oligomer having at least one active energy ray curable group is at least 1 per 100 parts by mass of the active energy ray non-curable polymer component. The monomer and/or oligomer having one or more active energy ray-curable groups is preferably 1 part by mass or more, particularly preferably 60 parts by mass or more. The compounding ratio is preferably 200 parts by mass or less of monomers and/or oligomers having at least one active energy ray-curable group per 100 parts by mass of the active energy ray non-curable polymer component, In particular, it is preferably 160 parts by mass or less.

Also in this case, the photopolymerization initiator (C), the additive (D) and the cross-linking agent (F) can be appropriately blended in the same manner as described above.

The pressure-sensitive adhesive layer preferably has a thickness of 1 μm or more, particularly preferably 5 μm or more. Moreover, the thickness is preferably 50 μm or less, particularly preferably 40 μm or less. When the thickness of the pressure-sensitive adhesive layer is within the above range, it becomes easier to achieve the desired adhesive strength to the work.

(3) Release sheet In the work processing sheet according to the present embodiment, even if a release sheet is laminated on the surface of the adhesive layer for the purpose of protecting the adhesive surface until the adhesive surface is attached to the work. good. The configuration of the release sheet is arbitrary, and an example thereof is a plastic film subjected to release treatment with a release agent or the like. Specific examples of plastic films 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-based, fluorine-based, long-chain alkyl-based, or the like can be used, and among these, a silicone-based release agent is preferable because it is inexpensive and provides stable performance. Although the thickness of the release sheet is not particularly limited, it is usually 20 μm or more and 250 μm or less.

(4) Other members In the work processing sheet according to the present embodiment, an adhesive layer may be laminated on the adhesive surface of the adhesive layer. In this case, the work processing sheet according to the present embodiment can be used as a dicing/die bonding sheet by providing an adhesive layer as described above. In such a work processing sheet, a work is attached to the surface of the adhesive layer opposite to the pressure-sensitive adhesive layer, and the adhesive layer is diced together with the work, thereby laminating the individualized adhesive layers. you can get the chips The chip can be easily fixed to a target on which the chip is mounted by means of the individualized adhesive layer. Examples of the material constituting the adhesive layer include those containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, those containing a B-stage (semi-cured) thermosetting adhesive component, and the like. It is preferable to use

In addition, in the work processing sheet according to the present embodiment, a protective film-forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the work processing sheet according to this embodiment can be used as a protective film-forming and dicing sheet. In such a work processing sheet, a work is attached to the surface of the protective film forming layer opposite to the adhesive layer, and the protective film forming layer is diced together with the work to form individualized protective films. A chip with stacked layers can be obtained. As the work, one having a circuit formed on one side is preferably used. In this case, a protective film-forming layer is usually laminated on the side opposite to the side on which the circuit is formed. By curing the individualized protective film-forming layer at a predetermined timing, a protective film having sufficient durability can be formed on the chip. The protective film-forming layer is preferably made of an uncured curable adhesive.

In the work processing sheet according to the embodiment of the present application, the oxygen atomic ratio R ₀ and the oxygen atomic ratio R ₁₀₀ are within the ranges described above. When forming layers are laminated, the oxygen atomic ratio R ₀ and the oxygen atomic ratio R ₁₀₀ of the pressure-sensitive adhesive layer before these layers are laminated should be within the ranges described above.

3. Method for manufacturing work processing sheet The method for manufacturing the work processing sheet according to the present embodiment is not particularly limited. Preferably, the work processing sheet according to the present embodiment has an adhesive layer laminated on one side of the substrate. Manufactured by

Lamination of the pressure-sensitive adhesive layer on one side of the substrate can be performed by a known method. For example, it is preferable to transfer the pressure-sensitive adhesive layer formed on the release sheet to one side of the substrate. In this case, the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, if desired, a coating solution containing a solvent or a dispersion medium is prepared, and the release-treated surface of the release sheet (hereinafter sometimes referred to as "release surface") ), the coating liquid is applied to the above by a die coater, a curtain coater, a spray coater, a slit coater, a knife coater, etc. to form a coating film, and the coating film is dried to form an adhesive layer. be able to. The properties of the coating liquid are not particularly limited as long as the coating liquid can be applied. The release sheet in this laminate may be peeled off as a process material, or may be used to protect the adhesive surface of the adhesive layer until the work processing sheet is attached to the work.

When the coating liquid for forming the pressure-sensitive adhesive layer contains a cross-linking agent, by changing the above drying conditions (temperature, time, etc.) or by separately providing heat treatment, the inside of the coating film The cross-linking reaction between the active energy ray-curable polymer (A) or the active energy ray-non-curable polymer and the cross-linking agent may be allowed to proceed to form a cross-linked structure with a desired existence density in the pressure-sensitive adhesive layer. In order to allow the cross-linking reaction to proceed sufficiently, after laminating the pressure-sensitive adhesive layer on the base material by the method described above, the obtained work processing sheet is placed in an environment of, for example, 23° C. and a relative humidity of 50% for several days. Curing such as leaving still may be performed.

Instead of transferring the pressure-sensitive adhesive layer formed on the release sheet to one side of the substrate as described above, the pressure-sensitive adhesive layer may be formed directly on the substrate. In this case, the adhesive layer is formed by applying the coating liquid for forming the adhesive layer described above to one side of the substrate to form a coating film, and drying the coating film.

4. Method of Using Work Processing Sheet The work processing sheet according to the present embodiment can be used for processing a work. That is, after the adhesive surface of the work processing sheet according to the present embodiment is attached to the work, the work can be processed on the work processing sheet. Depending on the processing, the work processing sheet according to the present embodiment can be used as a back grinding sheet, a dicing sheet, an expanding sheet, a pick-up sheet, or the like. Examples of the workpiece include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

Further, when the work processing sheet according to the present embodiment includes the above-described adhesive layer, the work processing sheet can be used as a dicing/die bonding sheet. Furthermore, when the work processing sheet according to the present embodiment includes the protective film forming layer described above, the work processing sheet can be used as a protective film forming and dicing sheet.

In the work processing sheet according to the present embodiment, the oxygen atomic ratio R ₁₀₀ measured by X-ray photoelectron spectroscopy at a position in the adhesive layer at a depth of 100 nm from the adhesive surface is within the above-described range, Even if the adhesive constituting the adhesive layer adheres to the work after processing, the adhesive can be removed satisfactorily by running water. Furthermore, since the oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the adhesive surface is within the above-described range, it becomes easier to separate the workpiece after processing. Therefore, the work processing sheet according to the present embodiment is preferably used for processing in which running water is used, and is particularly preferably used for dicing that involves supplying running water to the cut portion. be. That is, the work processing sheet according to this embodiment is preferably used as a dicing sheet.

When the work processing sheet according to the present embodiment is used as a dicing sheet, general conditions can be used as the conditions for dicing and the conditions for supplying running water. In particular, regarding the supply conditions of running water, it is preferable to use pure water or the like as water to be used. The amount of water supplied is preferably 0.5 L/min or more, particularly preferably 1 L/min or more. Also, the amount of water supplied is preferably 2.5 L/min or less, and particularly preferably 2 L/min or less. The temperature of the water is not particularly limited, and is preferably about room temperature, for example.

[Manufacturing method of machined work]
A method for manufacturing a processed work according to one embodiment of the present invention includes a bonding step of bonding a surface of the adhesive layer of the work processing sheet opposite to the base material and the work, and processing the work. A processing step of obtaining a processed work laminated on the work processing sheet by processing the work on the work sheet, and irradiating the adhesive layer with active energy rays to harden the adhesive layer. , an irradiation step of reducing the adhesion of the work processing sheet to the processed work, and a separation step of separating the processed work from the work processing sheet after the active energy ray irradiation.

In the work processing sheet used in the method for manufacturing a processed work of the present embodiment, even if the adhesive constituting the adhesive layer adheres to the work after processing, the adhesive can be removed by running water. It can be removed and facilitates good separation of machined workpieces. Therefore, according to the method for manufacturing a machined work of the present embodiment, it is possible to efficiently produce a machined work.

Each step in the method for manufacturing a machined work according to this embodiment will be described below.

(1) Bonding step Bonding of the work and the work processing sheet in the bonding step can be performed by a conventionally known method. In addition, when dicing the work in the subsequent processing step, it is preferable to bond a ring frame to a region on the outer peripheral side of the region where the work is bonded on the adhesive layer side surface of the work processing sheet. . Moreover, the work to be used may be any desired one according to the processed work to be manufactured, and as a specific example, the work described above can be used.

(2) Machining Process In the machining process, desired machining can be performed on the workpiece, for example, back grinding, dicing, and the like can be performed. These processes can be performed by conventionally known methods.

When performing blade dicing using a rotating blade as the above processing, generally, a part of the pressure-sensitive adhesive layer on the work processing sheet is cut together with the work. At that time, the adhesive forming the adhesive layer may be rolled up by the blade and adhere to the processed workpiece. However, in the work processing sheet used in the method for manufacturing a processed work of the present embodiment, the adhering adhesive can be removed satisfactorily by running water, as described above. From this point of view, the processing in the present embodiment is preferably dicing, and particularly preferably blade dicing using a rotating blade.

(3) Irradiation step In the irradiation step, the conditions for irradiating the active energy ray are not limited as long as the adhesion of the work processing sheet to the processed work can be reduced to a desired degree, and the irradiation is performed based on a conventionally known method. It can be carried out. Types of active energy rays to be used include, for example, ionizing radiation, that is, X-rays, ultraviolet rays, electron beams, etc. Among them, ultraviolet rays, which are relatively easy to introduce irradiation equipment, are preferable.

(4) Separation process In the separation process, separation is performed by a method according to the type of processing and the obtained processed work. For example, dicing is performed as processing, and when chips obtained by singulating the work are obtained by the dicing, the obtained chips are individually picked from the work processing sheet using a conventionally known pick-up device. to pick up. Moreover, in order to facilitate the pickup, the work processing sheet may be expanded to separate the processed works.

(5) Others In the method for manufacturing a machined work according to the present embodiment, steps other than the steps described above may be provided. For example, after the lamination step, a transport step of transporting the obtained laminate of the work and the work processing sheet to a predetermined position, a storage step of storing the laminate for a predetermined period, and the like may be provided. Further, after the separating process, a mounting process or the like of mounting the obtained processed work on a predetermined base or the like may be provided.

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

For example, another layer may be provided between the substrate and the adhesive layer, or on the surface of the substrate opposite to the adhesive layer.

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

[Example 1]
(1) Preparation of adhesive composition Acrylic copolymer obtained by copolymerizing 20 parts by mass of methyl acrylate, 60 parts by mass of 2-methoxyethyl acrylate, and 20 parts by mass of 2-hydroxyethyl acrylate. The coalescence is reacted with methacryloyloxyethyl isocyanate (MOI) of 21.4 g (corresponding to 80 mol% with respect to the number of moles of 2-hydroxyethyl acrylate) per 100 g of the acrylic copolymer. , to obtain an active energy ray-curable polymer. When the weight average molecular weight (Mw) of this active energy ray-curable polymer was measured by the method described later, it was 600,000.

100 parts by mass of the obtained active energy ray-curable polymer (in terms of solid content, hereinafter the same) and 3 parts by mass of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, product name “Irgacure 184”) as a photopolymerization initiator. and 9.32 parts by mass of toluene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a cross-linking agent, and an active energy ray-polymerizable branched polymer as an additive (manufactured by Nissan Chemical Industries, Ltd., product name "OD -007", weight average molecular weight: 14000) and 0.18 parts by mass were mixed in a solvent to obtain an adhesive composition.

(2) Formation of adhesive layer On the release surface of a release sheet (manufactured by Lintec, product name "SP-PET381031") consisting of a polyethylene terephthalate film with a thickness of 38 μm and a silicone-based release agent layer formed on one side After applying the above adhesive composition and drying it by heating, it was aged for 7 days under conditions of 23° C. and 50% RH to form a 5 μm thick adhesive layer on the release sheet.

(3) Preparation of work processing sheet The surface of the pressure-sensitive adhesive layer formed in the above step (2) on the side opposite to the release sheet and an ethylene-methacrylic acid copolymer (EMAA) film with a thickness of 80 μm as a base material A work processing sheet was obtained by laminating one side of the sheet.

Here, the weight average molecular weight (Mw) described above is a weight average molecular weight in terms of standard polystyrene measured using gel permeation chromatography (GPC) (GPC measurement).

[Example 2 and Comparative Examples 1 to 3]
A work processing sheet was produced in the same manner as in Example 1, except that the composition of the acrylic copolymer, the content of the cross-linking agent and the content of the additive were changed as shown in Table 1.

[Test Example 1] (Measurement of oxygen atomic ratio)
The release sheet was peeled off from the work processing sheets produced in Examples and Comparative Examples, and the oxygen atom ratio (%) in the exposed surface (adhesive surface) of the exposed adhesive layer and the adhesion at a depth of 100 nm from the exposed surface The oxygen atomic ratio (%) in the agent layer was measured using an X-ray photoelectron spectrometer (manufactured by ULVAC-PHI, product name “PHI Quantera SXM”), and the oxygen atomic ratio at the “0 nm position” ( %) and the oxygen atom ratio (%) at the “100 nm position”. Table 1 shows the results.

[Test Example 2] (Measurement of adhesive strength)
By peeling off the release sheet from the work processing sheets produced in Examples and Comparative Examples, superimposing the exposed surface of the exposed pressure-sensitive adhesive layer on the mirror surface of a mirror-finished 6-inch silicon wafer, and reciprocating a 2-kg roller once. A sample for adhesion measurement was obtained by laminating with a load applied and left for 20 minutes.

For the adhesive force measurement sample, the work processing sheet was peeled from the silicon wafer at a peeling speed of 300 mm / min and a peeling angle of 180 °, and the adhesion to the silicon wafer was performed by a 180 ° peeling method according to JIS Z0237: 2009. Force (mN/25 mm) was measured. The results are shown in Table 1 as adhesive strength before ultraviolet irradiation (before UV).

[Test Example 3] (Evaluation of Removability of Adhesive)
The release sheet is peeled off from the work processing sheets produced in Examples and Comparative Examples, and a tape mounter (manufactured by Lintec Corporation, product name "Adwill RAD2500m/12") is used on the exposed surface of the exposed adhesive layer to # A polished surface of a 2000-polished 6-inch silicon wafer (thickness: 150 μm) was attached. Then, using a dicing machine (manufactured by Disco, product name "DFD-6361"), dicing was performed by cutting from the 6-inch silicon wafer side while supplying running water to the cutting portion under the following dicing conditions.

<Dicing conditions>
・Dicing device: DFD-6361 manufactured by Disco
・Blade: Disco NBC-2H 2050 27HECC
・Blade width: 0.025 to 0.030 mm
・Blade length: 0.640 to 0.760mm
・Blade rotation speed: 50000 rpm
・Cutting speed: 20mm/sec
・Cut depth: 15 μm from the adhesive layer side surface of the work processing sheet
・Flowing water supply: 1.0 L/min
・Water temperature: Room temperature ・Cut size: 10mm x 10mm

Twenty chips obtained by the above dicing were separated from the work processing sheet, and whether or not the adhesive was adhered to them was visually confirmed. Then, the removability of the adhesive was evaluated based on the following criteria. Table 1 shows the results.
◯: There were no chips to which the adhesive had adhered.
x: One or more chips adhered with adhesive.

[Test Example 4] (Evaluation of Separability)
Dicing was performed in the same manner as in Test Example 3 using the work processing sheets produced in Examples and Comparative Examples. After completion of dicing, the surface of the work processing sheet side was irradiated with ultraviolet rays (UV) using an ultraviolet irradiation device (manufactured by Lintec, product name: RAD-2000) (illuminance: 230 mW/cm ² , light intensity: 190 mJ/cm ² ) to cure the adhesive layer. After that, all the obtained chips were picked up from the work processing sheet. At this time, the surface of the work processing sheet opposite to the surface to which the glass chip was attached was pushed up by needles (number of needles: 4, push-up speed: 50 mm/sec, push-up height: 0.5 mm). ). Based on the pick-up situation at this time, the separability when the chip was separated from the work processing sheet was evaluated according to the following criteria. Table 1 shows the results.
O: I was able to pick it up without any problems.
x: The chip could not be picked up well because the chip could not be separated or the chip was damaged.

Details of abbreviations and the like in Table 1 are as follows.
BA: butyl acrylate MMA: methyl methacrylate MA: methyl acrylate 2MEA: 2-methoxyethyl acrylate HEA: 2-hydroxyethyl acrylate

As can be seen from Table 1, according to the work processing sheets obtained in Examples, the pressure-sensitive adhesive can be satisfactorily removed by running water, and the work after processing can be separated satisfactorily. .

The work processing sheet of the present invention can be suitably used for dicing.

Claims (6)

A work processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate,
The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive,
The oxygen atomic ratio R ₀ measured by X-ray photoelectron spectroscopy on the surface of the pressure-sensitive adhesive layer opposite to the base material is 28 atomic % or less,
Among the positions in the pressure-sensitive adhesive layer, the oxygen atomic ratio R ₁₀₀ measured by X-ray photoelectron spectroscopy at a position at a depth of 100 nm from the surface of the pressure-sensitive adhesive layer opposite to the base material is 20 atomic % or more. , 29 atomic % or less. The value of the oxygen atomic ratio R ₀ is greater than the value of the oxygen atomic ratio R ₁₀₀ ,
Formula (1) below
Reduction rate of oxygen atomic ratio (%)={(oxygen atomic ratio R ₀ −oxygen atomic ratio R ₁₀₀ )/oxygen atomic ratio R ₀ }×100 (1)
2. The work processing sheet according to claim 1, wherein the reduction rate of the oxygen atomic ratio calculated from is 0% or more and 15% or less. 3. The work processing sheet according to claim 1, wherein the active energy ray-curable adhesive is an adhesive formed from an adhesive composition containing an active energy ray-polymerizable branched polymer. . The pressure-sensitive adhesive composition is an active energy ray-curable polymer obtained by reacting an acrylic copolymer having a functional group-containing monomer unit and an unsaturated group-containing compound having a functional group that binds to the functional group. contains
The acrylic copolymer is selected from methyl acrylate, 2-methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate and methoxyethylene glycol (meth)acrylate as a monomer unit constituting the polymer. 4. The work processing sheet according to claim 3 , comprising at least one of The work processing sheet according to any one of claims 1 to 4, which is a dicing sheet. A lamination step of laminating the surface of the adhesive layer of the work processing sheet according to any one of claims 1 to 5 opposite to the base material and the work,
a processing step of obtaining a processed work stacked on the work processing sheet by processing the work on the work processing sheet;
an irradiation step of irradiating the adhesive layer with an active energy ray to cure the adhesive layer and reduce the adhesive strength of the work processing sheet to the processed work;
and a separation step of separating the processed work from the work processing sheet that has been irradiated with active energy rays.