JP7086102B2 - Manufacturing method of workpiece sheet and processed workpiece - Google Patents

Description

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, these may be collectively referred to as "cutted objects") are manufactured in a large diameter state, and these are element small pieces (hereinafter, "elementary pieces"). It may be described as "chip"), and after being cut (diced) and individually separated (picked up), it is transferred to the next step, the mounting step. At this time, the material to be cut such as a semiconductor wafer is attached to a work processing sheet provided with a base material and an adhesive layer, and is subjected to each step of dicing, cleaning, drying, expanding, picking up and mounting. Ru.

In the above-mentioned dicing step, the dicing blade, the object to be cut, and the sheet for processing the work are heated by the frictional heat generated between the rotating dicing blade and the object to be cut or the sheet for processing the work. Further, in the dicing step, a cutting piece is generated from the object to be cut or the work sheet, and it may adhere to the object to be cut.

Therefore, when performing the dicing step, usually, running water is supplied to the cut portion to cool the dicing blade and the like, and the generated cutting piece is removed from the object to be cut.

In Patent Document 1, for the purpose of promoting the removal of cutting pieces by such running water, the contact angle of the surface of the pressure-sensitive adhesive layer opposite to the substrate in the pressure-sensitive adhesive layer before irradiation with ultraviolet rays is 82 ° to 114 ° with respect to pure water. There is disclosed a work sheet having a contact angle with respect to methylene iodide of 44 ° to 64 ° and a peak value of the probe tack test of 294 to 578 kPa in the pressure-sensitive adhesive layer before irradiation with ultraviolet rays. ..

Patent No. 5019657

However, when the dicing step is performed using a conventional work processing sheet as disclosed in Patent Document 1, the pressure-sensitive adhesive derived from the pressure-sensitive adhesive layer of the work processing sheet is sufficiently removed from the object to be cut. I couldn't.

Further, in general, due to the supply of running water during dicing, water may infiltrate into the interface between the work processing sheet and the object to be cut and the interface between the work processing sheet and the obtained insert. .. When such water intrusion occurs, chip skipping and chip chipping may occur.

The present invention has been made in view of such an actual situation, and while suppressing the infiltration of water at the interface between the work processing sheet and the object to be cut and the interface between the work processing sheet and the obtained chip. A work processing sheet capable of satisfactorily removing the pressure-sensitive adhesive derived from the pressure-sensitive adhesive layer adhering to the material to be cut during processing of the material to be cut, such as a semiconductor wafer, from the material to be cut by running water. It is an object of the present invention to provide a method for manufacturing a processed work using the work processing sheet.

In order to achieve the above object, first, the present invention is a work processing sheet including a base material and a pressure-sensitive adhesive layer laminated on one side of the base material, and the pressure-sensitive adhesive layer is active. It is composed of an energy ray-curable pressure-sensitive adhesive, and the water contact angle of the surface of the pressure-sensitive adhesive layer on the side opposite to the base material is 50 ° or more and 80 ° or less, and the silicon wafer of the work processing sheet. The adhesive strength to the work processing sheet was F1, and the adhesive strength of the work processing sheet to the silicon wafer after being immersed in distilled water at 23 ° C. for 12 hours and further dried at 23 ° C. for 24 hours was defined as F2. When, the following formula (1)
Adhesive strength reduction rate (%) = {(F1-F2) / F1} x 100 ... (1)
Provided is a work processing sheet characterized in that the reduction rate of the adhesive strength calculated from the above is 20% or more and 50% or less (Invention 1).

In the work processing sheet according to the above invention (Invention 1), the above-mentioned water contact angle is in the above range and the above-mentioned reduction rate of the adhesive force is in the above range. The infiltration of water at the interface between the work and the interface between the work sheet and the obtained chip is suppressed. Further, when the above-mentioned water contact angle is in the above range, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer has a predetermined affinity for water, and the above-mentioned reduction rate of the pressure-sensitive adhesive force is in the above-mentioned range. Therefore, the adhesive strength of the adhesive adhering to the object to be cut is appropriately reduced by contact with water, so that the adhesive adhering to the object to be cut can be satisfactorily removed by running water. It will be possible.

In the above invention (Invention 1), the adhesive strength F1 is preferably 1000 mN / 25 mm or more and 10,000 mN / 25 mm or less (Invention 2).

In the above inventions (Inventions 1 and 2), the adhesive strength F2 is preferably 900 mN / 25 mm or more and 8000 mN / 25 mm or less (Invention 3).

In the above inventions (Inventions 1 to 3), the active energy ray-curable pressure-sensitive adhesive has methyl acrylate, 2-methoxyethyl (meth) acrylate, and ethyl carbi (meth) acrylate as the monomer units constituting the polymer. It is preferable that the pressure-sensitive adhesive is formed from a pressure-sensitive adhesive composition containing an acrylic copolymer containing at least one selected from tall and methoxyethylene glycol (meth) acrylate (Invention 4).

In the above inventions (Inventions 1 to 4), a dicing sheet is preferable (Invention 5).

Secondly, the present invention comprises a bonding step of bonding the work to the surface of the pressure-sensitive adhesive layer of the work processing sheet (invention 1 to 5) opposite to the base material, and the work processing. A processing step of processing the work on a sheet to obtain a processed work laminated on the work processing sheet, and irradiating the pressure-sensitive adhesive layer with active energy rays to obtain the pressure-sensitive adhesive layer. It is provided with an irradiation step of reducing the adhesive force of the work processing sheet to the processed work and a separation step of separating the processed work from the work processing sheet after irradiation with active energy rays. (Invention 6), the present invention provides a method for manufacturing a processed work, which is characterized by the above.

The work-working sheet according to the present invention is to be cut of a semiconductor wafer or the like while suppressing the infiltration of water at the interface between the work-working sheet and the object to be cut and the interface between the work-working sheet and the obtained chip. The pressure-sensitive adhesive derived from the pressure-sensitive adhesive layer adhering to the material to be cut during processing of the material can be satisfactorily removed from the material to be cut by running water. Further, according to the method for manufacturing a processed work according to the present invention, the processed work can be efficiently manufactured.

Hereinafter, embodiments of the present invention will be described.
[Work processing sheet]
The work processing sheet according to the present embodiment includes a base material and an adhesive layer laminated on one side of the base material.

1. 1. Physical Properties of Work Sheet In the work sheet according to the present embodiment, the water contact angle of the surface of the pressure-sensitive adhesive layer opposite to the base material (hereinafter, may be referred to as “adhesive surface”) is 50 °. Above, it is 80 ° or less. When this water contact angle is within the above range, the pressure-sensitive adhesive layer exhibits an appropriate affinity for water, and when the work-working sheet is used for dicing the work piece, the work-working sheet is used. While suppressing the infiltration of water into the interface between the material to be cut and the interface between the work processing sheet and the obtained chip, the pressure-sensitive adhesive derived from the pressure-sensitive adhesive layer adhering to the material to be cut is satisfactorily removed by running water. It becomes possible to do. In the present specification, the water contact angle means the one measured before the active energy ray is irradiated to the work processing sheet.

On the other hand, if the water contact angle is less than 50 °, the adhesive layer becomes excessively compatible with water and cannot suppress the infiltration of water, which causes chip skipping and chip during dicing. Chips occur. Further, when the water contact angle exceeds 80 °, the affinity of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer with water becomes insufficient, and the pressure-sensitive adhesive adhering to the object to be cut cannot be sufficiently removed by running water. Will be.

From the above viewpoint, the water contact angle is preferably 55 ° or more, and particularly preferably 60 ° or more. The water contact angle is preferably 75 ° or less, and particularly preferably 70 ° or less. The details of the above-mentioned method for measuring the water contact angle are as described in the test examples described later.

Further, in the work processing sheet according to the present embodiment, the adhesive force of the work processing sheet to the silicon wafer is set to F1, the work processing sheet is immersed in distilled water at 23 ° C. for 12 hours, and further dried at 23 ° C. for 24 hours. When the adhesive force of the work processing sheet to the silicon wafer is F2, the following formula (1)
Adhesive strength reduction rate (%) = {(F1-F2) / F1} x 100 ... (1)
The rate of decrease in adhesive strength calculated from is 20% or more and 50% or less. When the decrease rate of the adhesive force is within the above range, when the adhesive layer is exposed to the running water supplied to the cut portion in the dicing step, the adhesive layer has an appropriate adhesive force to the object to be cut. Derived from the adhesive layer adhering to the work piece while suppressing the infiltration of water into the interface between the work processing sheet and the object to be cut and the interface between the work sheet and the obtained chip. The adhesive can be satisfactorily removed by running water. In addition, in this specification, the adhesive force F1 and the adhesive force F2 are both the adhesive force measured before the active energy ray is irradiated to the work processing sheet.

On the other hand, when the above-mentioned reduction rate of the adhesive strength is less than 20%, the adhesive strength of the adhesive to the object to be cut is maintained even after the adhesive derived from the adhesive layer is exposed to running water, and the adhesive is covered. The adhesive adhering to the cut piece cannot be sufficiently removed by running water. Further, when the above-mentioned reduction rate of the adhesive force exceeds 50%, the adhesive force of the adhesive layer to the object to be cut is excessively decreased, and the object to be cut and the obtained chip are well held on the adhesive layer. This makes it impossible to peel off the material to be cut, and chip skipping and chip chipping occur during dicing.

From such a viewpoint, the above-mentioned reduction rate of the adhesive strength is preferably 23% or more. The rate of decrease in the adhesive strength described above is preferably 40% or less.

In the work processing sheet according to the present embodiment, the above-mentioned adhesive force F1 is preferably 1000 mN / 25 mm or more, particularly preferably 2000 mN / 25 mm or more, and further preferably 3000 mN / 25 mm or more. .. Further, the adhesive strength F1 is preferably 10,000 mN / 25 mm or less, and particularly preferably 7,000 mN / 25 mm or less.

Further, in the work processing sheet according to the present embodiment, the above-mentioned adhesive force F2 is preferably 900 mN / 25 mm or more, particularly preferably 1500 mN / 25 mm or more, and further preferably 2000 mN / 25 mm or more. Is preferable. Further, the adhesive strength F2 is preferably 8000 mN / 25 mm or less, and particularly preferably 5000 mN / 25 mm or less.

When the adhesive force F1 and the adhesive force F2 are each in the above range, it becomes easy to adjust the reduction rate of the adhesive force within the above range. The details of the method for measuring the adhesive force F1 and the adhesive force F2 are as described in the test examples described later.

2. 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 the adhesive layer is preferably cured. It is not particularly limited as long as it exhibits good permeability to the active energy rays irradiated for the purpose.

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

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

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

Although the thickness of the base material can be appropriately set depending on the method in which the work processing sheet is used, it is usually preferably 20 μm or more, and particularly preferably 25 μm or more. The thickness is usually preferably 450 μm or less, and 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 exhibits a desired adhesive force to the object to be cut. The work sheet is not particularly limited as long as it can achieve the above-mentioned reduction rate of water contact angle and adhesive strength. Since the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive, when the object to be cut attached to the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer is separated from the pressure-sensitive adhesive surface, it is adhered by irradiation with active energy rays. The agent layer can be cured to reduce the adhesive force of the work processing sheet to the object to be cut. This facilitates the separation of the adhesive surface of the adhesive layer and the object to be cut.

The active energy ray-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be mainly composed of a polymer having active energy ray-curing property, or may be an active energy ray-curable polymer (active energy ray-curable polymer). It may be mainly composed of a mixture of a polymer having no polymer) and a monomer and / or an oligomer having at least one active energy ray-curable group. Further, it may be a mixture of a polymer having active energy ray curability and an active energy ray non-curable polymer. Further, it may be a mixture of a polymer having active energy ray curability and a monomer and / or an oligomer having at least one or more active energy ray curable groups. Further, it may be a mixture of a polymer having active energy ray curability, an active energy ray non-curable polymer, and a monomer and / or an oligomer having at least one or more active energy ray curable groups.

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

The polymer having active energy ray curability is a (meth) acrylic acid ester (co) polymer (A) in which a functional group having active energy ray curability (active energy ray curable group) is introduced into the side chain (hereinafter referred to as “)”. It may be referred to as "active energy ray-curable polymer (A)"). The 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 bonded to the functional group. It is preferably obtained by reacting.

The acrylic copolymer (a1) may be referred to as a monomer for adjusting the hydrophilicity of the acrylic copolymer (a1) (hereinafter, referred to as “hydrophilicity adjusting monomer”” as a monomer unit constituting the polymer. ) Is preferably included, and specific examples thereof include methyl acrylate, 2-methoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate (ethoxyethoxyethyl (meth) acrylate) and (meth). ) It is preferable to contain at least one selected from methoxyethylene glycol acrylate. These monomers can improve the hydrophilicity of the acrylic copolymer (a1), whereby the water contact angle and the reduction rate of the adhesive force in the formed pressure-sensitive adhesive layer can be easily adjusted to the above-mentioned ranges. Become. From the viewpoint of easily obtaining such an effect, the acrylic copolymer (a1) is a monomer unit constituting the polymer, among the above-mentioned monomers, methyl acrylate, 2-methoxyethyl acrylate and methoxy acrylate. It is preferable to contain at least one of ethylene glycol.

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, and particularly 20% by mass or more. Is preferable, and more preferably 30% by mass or more. The content of methyl acrylate is preferably 85% by mass or less. With these contents, it becomes easy to adjust the water contact angle and the reduction rate of the adhesive force in the formed adhesive layer within the above-mentioned ranges. In the present specification, the above-mentioned content (% by mass) of methyl acrylate means the content with respect to all the monomers constituting the acrylic copolymer (a1). Further, the content (% by mass) of other monomers described later also means the content with respect to all the monomers constituting the acrylic copolymer (a1).

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, and 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, and further preferably 70% by mass or less. With these contents, it becomes easy to adjust the water contact angle and the reduction rate of the adhesive force in the formed adhesive layer within the above-mentioned ranges.

When the acrylic copolymer (a1) contains both methyl acrylate and 2-methoxyethyl acrylate as the monomer unit constituting the polymer, the content of methyl acrylate and 2-methoxyethyl acrylate is high. 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. The total value is preferably 90% by mass or less, and particularly preferably 85% by mass or less. When the total value is in these ranges, it becomes easy to adjust the water contact angle and the reduction rate of the adhesive force in the formed pressure-sensitive adhesive layer by the above-mentioned ranges.

Further, 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. It is preferably mass% or more. The content of methoxyethylene glycol acrylate is preferably 85% by mass or less, and particularly preferably 80% by mass or less. With these contents, it becomes easy to adjust the water contact angle and the reduction rate of the adhesive force in the formed adhesive layer within the above-mentioned ranges.

The acrylic copolymer (a1) preferably contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth) acrylic acid ester monomer or a derivative thereof, in addition to the above-mentioned hydrophilicity-adjusting monomer. ..

The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) has a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, a substituted amino group and an epoxy group in the molecule. It is preferable that the monomer is contained in.

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (. Examples thereof include 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate, which may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

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

The acrylic copolymer (a1) preferably contains 1% by mass or more of the structural unit derived from the functional group-containing monomer, particularly preferably 5% by mass or more, and further contains 10% by mass or more. It is preferable to do so. Further, the acrylic copolymer (a1) preferably contains the structural unit derived from the functional group-containing monomer in an amount of 35% by mass or less, and particularly preferably in an amount of 30% by mass or less.

As the (meth) acrylic acid ester monomer constituting the acrylic copolymer (a1), in addition to the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, for example, an alicyclic type in the molecule. A monomer having a structure (monomer containing an alicyclic structure) is preferably used.

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

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

Further, the acrylic copolymer (a1) preferably contains 50% by mass or more, and particularly preferably 60% by mass or more, a structural unit derived from the (meth) acrylic acid ester monomer or a derivative thereof. Further, it is preferably contained in an amount of 70% by mass or more. Further, the acrylic copolymer (a1) preferably contains a structural unit derived from the (meth) acrylic acid ester monomer or a derivative thereof in an amount of 99% by mass or less, and particularly preferably in an amount of 95% by mass or less. It is preferable, and it is preferable that it is contained in an amount of 90% by mass or less.

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

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

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

Further, the unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6, and more preferably 1 to 4 active energy ray-polymerizable carbon-carbon double bonds in one molecule. It has been. Specific examples of such an unsaturated group-containing compound (a2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1-(. Bisacrylloyloxymethyl) ethyl isocyanate; Acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth) acrylate; a diisocyanate compound or a polyisocyanate compound, a polyol compound, and a (meth) acrylic. Acryloyl monoisocyanate compound obtained by reaction with hydroxyethyl acid acid; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-oxazolin, 2 -Isocyanate-2-oxazoline and the like can be mentioned.

The unsaturated group-containing compound (a2) is preferably 50 mol% or more, particularly preferably 60 mol% or more, still more preferably 60 mol% or more, based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). It is used in a proportion of 70 mol% or more. The unsaturated group-containing compound (a2) is preferably 95 mol% or less, particularly preferably 93 mol% or less, and further preferably 93 mol% or less, based on the number of moles of the functional group-containing monomer of 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) are used. Depending on the combination, the reaction temperature, pressure, solvent, time, presence / absence of catalyst, and type of catalyst can be appropriately selected. As a result, the functional group present in the acrylic copolymer (a1) reacts with the functional group in the unsaturated group-containing compound (a2), and the unsaturated group is contained in the acrylic copolymer (a1). Introduced into the side chain, the active energy ray-curable polymer (A) is obtained.

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, and further preferably 200,000 or more. It is preferable to have it. The weight average molecular weight (Mw) is preferably 1.5 million or less, and particularly preferably 1 million or less. The weight average molecular weight (Mw) in the present specification is a value in terms of standard polystyrene measured by a gel permeation chromatography method (GPC method).

Even when the active energy ray-curable pressure-sensitive adhesive contains a polymer having active energy ray-curable properties such as the active energy ray-curable polymer (A) as a main component, the active energy ray-curable pressure-sensitive adhesive has active energy. It may further contain a linear curable monomer and / or an oligomer (B).

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

Examples of the active energy ray-curable monomer and / or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and trimethyl propantri (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 Examples thereof include polyfunctional acrylic acid esters such as glycol di (meth) acrylate and dimethylol tricyclodecandi (meth) acrylate, polyester oligo (meth) acrylate, and polyurethane oligo (meth) acrylate.

When the active energy ray-curable monomer and / or the oligomer (B) is blended with the active energy ray-curable polymer (A), the active energy ray-curable monomer and / or the active energy ray-curable monomer in the active energy ray-curable pressure-sensitive adhesive. Alternatively, the content of the oligomer (B) is preferably more than 0 parts by mass, and particularly preferably 60 parts by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). The content is preferably 250 parts by mass or less, and particularly preferably 200 parts by mass or less, with respect to 100 parts by mass of the active energy ray-curable polymer (A).

Here, when ultraviolet rays are used as the active energy rays for curing the active energy ray-curable pressure-sensitive adhesive, it is preferable to add a photopolymerization initiator (C), and the photopolymerization initiator (C) is used. Therefore, the polymerization curing time and the amount of light irradiation can be reduced.

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

When the photopolymerization initiator (C) contains the active energy ray-curable polymer (A) (active energy ray-curable monomer and / or oligomer (B), the active energy ray-curable polymer (A) ) And the total amount of the active energy ray-curable monomer and / or oligomer (B) 100 parts by mass) 0.1 parts by mass or more, particularly 0.5 parts by mass or more with respect to 100 parts by mass. preferable. Further, when the photopolymerization initiator (C) contains the active energy ray-curable polymer (A) (active energy ray-curable monomer and / or oligomer (B), the active energy ray-curable polymer) (A) and the total amount of the active energy ray-curable monomer and / or oligomer (B) 100 parts by mass) It is preferable to use the amount of 10 parts by mass or less, particularly 6 parts by mass or less with respect to 100 parts by mass.

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

Examples of the active energy ray non-curable polymer component or oligomer component (D) include polyacrylic acid esters, polyesters, polyurethanes, polycarbonates, polyolefins, etc., and polymers having a weight average molecular weight (Mw) of 30 to 2.5 million or Oligomers are preferred. By blending the component (D) with an active energy ray-curable pressure-sensitive adhesive, the tackiness and peelability before curing, the strength after curing, the adhesiveness with other layers, the storage stability and the like can be improved. The blending amount of the component (D) 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 (E), a polyfunctional compound having reactivity with a functional group 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, etc. Reactive phenolic resins and the like can be mentioned.

The blending amount of the cross-linking agent (E) is preferably 0.01 part by mass or more, and particularly preferably 3 parts by mass or more, with respect to 100 parts by mass of the active energy ray-curable polymer (A). The amount of the cross-linking agent (E) to be blended is preferably 20 parts by mass or less, and particularly preferably 17 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

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

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

As the monomer and / or oligomer having at least one or more active energy ray-curable groups, the same one as the above-mentioned component (B) can be selected. The blending ratio of the active energy ray non-curable polymer component to the monomer and / or oligomer having at least one active energy ray curable group is at least 1 with respect to 100 parts by mass of the active energy ray non-curable polymer component. The amount is preferably 1 part by mass or more, and particularly preferably 60 parts by mass or more, of the monomer and / or the oligomer having two or more active energy ray-curable groups. Further, the compounding ratio is preferably 200 parts by mass or less of the monomer and / or the oligomer having at least one active energy ray-curable group with respect to 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) and the cross-linking agent (E) can be appropriately blended in the same manner as described above.

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 5 μm or more. The thickness is preferably 50 μm or less, more preferably 40 μm or less. When the thickness of the pressure-sensitive adhesive layer is within the above range, it becomes easy to achieve the above-mentioned reduction rate of the pressure-sensitive adhesive force.

(3) Release sheet In the work processing sheet according to the present embodiment, a release sheet is laminated on the adhesive layer for the purpose of protecting the surface until the adhesive surface is attached to the object to be cut. You may. 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, and among these, a silicone type which can obtain stable performance at a low cost is preferable. The thickness of the release sheet is not particularly limited, but is usually 20 μm or more and 250 μm or less.

(4) Other Members In the work processing sheet according to the present embodiment, the 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 the adhesive layer as described above. In such a work processing sheet, an object to be cut is attached to the surface of the adhesive layer opposite to the adhesive layer, and the adhesive layer is diced together with the object to be cut to achieve individualized adhesion. It is possible to obtain a chip in which the agent layer is laminated. The individualized adhesive layer makes it possible to easily fix the chip to the object on which the chip is mounted. As the material constituting the above-mentioned adhesive layer, a material containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, a material containing a B stage (semi-curable) thermosetting adhesive component, and the like are used. It is preferable to use it.

Further, 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 the present embodiment can be used as a protective film forming and dicing sheet. In such a work processing sheet, a cut piece 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 cut piece to be individualized. It is possible to obtain a chip on which the protective film forming layer is laminated. As the object to be cut, it is preferable to use one having a circuit formed on one side, and in this case, a protective film forming layer is usually laminated on a surface opposite to the surface on which the circuit is formed. .. The individualized protective film forming layer can be cured at a predetermined timing to form a protective film having sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

The work processing sheet according to the embodiment of the present application satisfies the above-mentioned water contact angle and the reduction rate of the adhesive force, but the above-mentioned adhesive layer or protective film forming layer is laminated on the adhesive layer. In this case, the pressure-sensitive adhesive layer before these layers are laminated may be sufficient to satisfy the above-mentioned water contact angle and adhesive strength.

3. 3. Method for Manufacturing Work Processing Sheet The method for manufacturing the work processing sheet according to the present embodiment is not particularly limited, and preferably, the work processing sheet according to the present embodiment has an adhesive layer laminated on one side of the base material. Manufactured by

The adhesive layer can be laminated on one side of the base material 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 base material. In this case, a pressure-sensitive composition constituting the pressure-sensitive adhesive layer and, if desired, a coating liquid containing a solvent or a dispersion medium may be prepared and the peel-treated surface of the release sheet (hereinafter referred to as "peeling surface"). A coating liquid is applied onto the coating liquid using 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 it can be applied, and the coating liquid may contain a component for forming the pressure-sensitive adhesive layer as a solute or as a dispersoid. The peeling sheet in this laminated body may be peeled off as a process material, or may be used to protect the adhesive surface of the pressure-sensitive adhesive layer until the work processing sheet is attached to the object to be cut.

When the coating liquid for forming the pressure-sensitive adhesive layer contains a cross-linking agent, the inside of the coating film may be changed by changing the above-mentioned drying conditions (temperature, time, etc.) or by separately providing a heat treatment. 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 in the pressure-sensitive adhesive layer at a desired abundance density. In order to allow this cross-linking reaction to proceed sufficiently, after laminating the pressure-sensitive adhesive layer on the substrate by the above method or the like, 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 standing still may be performed.

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

4. How to use the work processing sheet The work processing sheet according to this embodiment can be used for processing a work (work piece). That is, after the adhesive surface of the work processing sheet according to the present embodiment is attached to the work piece, the work piece can be processed on the work piece. Depending on the processing, the work processing sheet according to the present embodiment can be used as a back grind sheet, a dicing sheet, an expand sheet, a pickup sheet, or the like. Here, examples of the object to be cut include a semiconductor wafer, a semiconductor member such as a semiconductor package, and a glass member such as a glass plate.

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

The work processing sheet according to the present embodiment is easy to remove the pressure-sensitive adhesive by running water even when the pressure-sensitive adhesive derived from the pressure-sensitive adhesive layer adheres to the object to be cut, and is used for work processing. Water caused by the running water is suppressed from entering the interface between the sheet and the object to be cut and the interface between the work sheet and the obtained chip. Therefore, the work processing sheet according to the present embodiment is preferably used for processing in which running water is used, and particularly preferably used for dicing accompanied by supplying running water to the cut portion. be. That is, it is preferable to use the work processing sheet according to the present embodiment 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 dicing conditions and the running water supply conditions. In particular, regarding the supply conditions of running water, it is preferable to use pure water or the like as the water to be used. The amount of water supplied is preferably 0.5 L / min or more, and particularly preferably 1 L / min or more. The amount of water supplied is preferably 2.5 L / min or less, and particularly preferably 2 L / min or less. The temperature of water is not particularly limited, and is preferably about room temperature, for example.

[Manufacturing method of processed workpiece]
The method for manufacturing a processed work according to an embodiment of the present invention includes a bonding step of bonding the work to the surface of the pressure-sensitive adhesive layer of the work processing sheet opposite to the base material, and the work processing. By processing the work on the work sheet, the processing process to obtain the processed work laminated on the work sheet, and the pressure-sensitive adhesive layer is irradiated with active energy rays to cure the pressure-sensitive adhesive layer. It is provided with an irradiation step of reducing the adhesive force of the work processing sheet to the processed work and a separation step of separating the processed work from the work processing sheet after irradiation with active energy rays.

The work processing sheet used in the method for manufacturing a processed work of the present embodiment suppresses the infiltration of water at the interface between the work processing sheet and the work or the work after processing, and is used during the processing of the work. The pressure-sensitive adhesive adhering to the work can be satisfactorily removed by running water. Therefore, according to the method for manufacturing a processed work of the present embodiment, it is possible to efficiently manufacture the processed work.

Hereinafter, each step in the method for manufacturing the processed work of the present embodiment will be described.

(1) Laminating step The laminating of the work and the work processing sheet in the laminating process can be performed by a conventionally known method. When dicing the work in the subsequent processing step, it is preferable to attach the ring frame to the outer peripheral side of the region to which the work is to be bonded on the surface of the work processing sheet on the pressure-sensitive adhesive layer side. .. Further, the work to be used may be a desired one according to the processed work to be manufactured, and as a specific example, the above-mentioned work can be used.

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

When blade dicing using a rotating blade is performed as the above processing, a part of the pressure-sensitive adhesive layer in the work processing sheet is generally cut together with the work. At that time, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be wound up by the blade and adhere to the processed work. However, in the work processing sheet used in the method for manufacturing the processed work of the present embodiment, as described above, the adhered adhesive can be satisfactorily removed by running water. 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 rays are not limited as long as the adhesive force of the work processing sheet to the processed work can be reduced to a desired degree, and the irradiation condition is based on a conventionally known method. It can be carried out. Examples of the type of active energy ray to be used include ionizing radiation, that is, X-ray, ultraviolet ray, electron beam and the like, and among them, ultraviolet ray which is relatively easy to introduce an irradiation facility is preferable.

(4) Separation step In the separation step, separation is performed by a method according to the type of processing and the obtained processed work. For example, when dicing is performed as processing and the dicing results in a chip in which the workpiece is separated into individual pieces, the obtained chips are individually separated from the workpiece processing sheet by using a conventionally known pickup device. Pick up. Further, in order to facilitate the pickup, the work processing sheet may be expanded to separate the processed works from each other.

(5) Others In the method for manufacturing a processed work of the present embodiment, a process other than the above-mentioned process may be provided. For example, after the bonding 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, or the like may be provided. Further, after the separation step, a mounting step or the like for mounting the obtained processed work on a predetermined substrate or the like may be provided.

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 provided between the base material and the pressure-sensitive adhesive layer, or on the surface of the base material opposite to the pressure-sensitive adhesive layer.

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

[Example 1]
(1) Preparation of Adhesive Composition Acrylic acid-based 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 21.4 g (corresponding to 80 mol% with respect to the number of moles of 2-hydroxyethyl acrylate) methacryloyloxyethyl isocyanate (MOI) with respect to 100 g of the acrylic copolymer. , An active energy ray-curable polymer was obtained. The weight average molecular weight (Mw) of this active energy ray-curable polymer was measured by the method described later and found to be 600,000.

100 parts by mass of the obtained active energy ray-curable polymer (solid content equivalent, the same applies hereinafter) and 3 parts by mass of 1-hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator. And 10.87 parts by mass of toluene diisocyanate (manufactured by Toso Co., Ltd., product name "Coronate L") as a cross-linking agent were mixed in a solvent to obtain a pressure-sensitive adhesive composition.

(2) Formation of adhesive layer With respect to the peeling surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET38131") in which a silicone-based release agent layer is formed on one side of a 38 μm-thick polyethylene terephthalate film. The pressure-sensitive adhesive composition was applied, dried by heating, and then cured under the conditions of 23 ° C. and 50% RH for 7 days to form a pressure-sensitive adhesive layer having a thickness of 5 μm on the release sheet.

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

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).

[Examples 2 to 6 and Comparative Examples 1 to 4]
A work processing sheet was produced in the same manner as in Example 1 except that the composition of the acrylic copolymer was changed as shown in Table 1 and the content of the cross-linking agent was changed as shown in Table 2.

[Test Example 1] (Measurement of water contact angle)
The release sheet is peeled off from the work processing sheet manufactured in Examples and Comparative Examples, and the water contact angle (°) on the exposed surface of the exposed adhesive layer is measured by a fully automatic contact angle measuring meter (manufactured by Kyowa Interface Science Co., Ltd., It was measured under the following conditions using the product name "DM-701"). The results are shown in Table 3.
-Amount of droplets of purified water: 2 μl
・ Measurement time: 3 seconds after dropping ・ Image analysis method: θ / 2 method

[Test Example 2] (Measurement of adhesive strength)
By peeling the release sheet from the work processing sheet manufactured in Examples and Comparative Examples, the exposed surface of the exposed adhesive layer is superposed on the mirror surface of the mirror-processed 6-inch silicon wafer, and the 2 kg roller is reciprocated once. A load was applied to bond them together, and the mixture was left for 20 minutes. After that, the work sheet is peeled from the silicon wafer at a peeling speed of 300 mm / min and a peeling angle of 180 °, and the adhesive force to the silicon wafer is F1 (mN / 25 mm) by the 180 ° peeling method according to JIS Z0237: 2009. ) Was measured. The results are shown in Table 3.

Further, the release sheet was peeled off from the work processing sheet produced in Examples and Comparative Examples, the exposed surface of the exposed pressure-sensitive adhesive layer was immersed in distilled water at 23 ° C. for 12 hours, and then dried at 23 ° C. for 24 hours. Then, the exposed surface was superposed on the mirror surface of the mirror-processed 6-inch silicon wafer, and a load was applied by reciprocating a 2 kg roller once to bond them together, and the mixture was left for 20 minutes. Subsequently, the work sheet is peeled from the silicon wafer at a peeling speed of 300 mm / min and a peeling angle of 180 °, and the silicon wafer after immersion and drying is subjected to a 180 ° peeling method according to JIS Z0237: 2009. The adhesive force F2 (mN / 25 mm) was measured. The results are shown in Table 3.

Further, using the values of the adhesive force F1 (mN / 25 mm) and the adhesive force F2 (mN / 25 mm) obtained as described above, the following formula (1)
Adhesive strength reduction rate (%) = {(F1-F2) / F1} x 100 ... (1)
The rate of decrease in adhesive strength (%) was calculated from. The results are shown in Table 3.

[Test Example 3] (Evaluation of adhesive removability)
A release sheet (manufactured by Lintec Corporation, product name "SP-PET38131") in which a silicone-based release agent layer is formed on one side of a polyethylene terephthalate film having a thickness of 38 μm, using the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples. A pressure-sensitive adhesive layer having a thickness of 5 μm was formed on the peeling sheet by applying the coating to the peeling surface of the above and drying it by heating. From the laminate of the pressure-sensitive adhesive layer and the release sheet thus obtained, 20 small pieces of the laminate having a size of 5 mm × 5 mm were cut out.

Subsequently, the surface of the 20 small pieces obtained as described above on the pressure-sensitive adhesive layer side was attached to the polished surface of the 6-inch silicon wafer (thickness: 150 μm) polished in # 2000, and then from the pressure-sensitive adhesive layer. The release sheets were peeled off. At the time of the pasting, the small pieces were pasted so as to have a space of 1 mm or more.

After that, the release sheet was peeled off from the work processing sheet manufactured in Examples and Comparative Examples, and a tape mounter (manufactured by Lintec Corporation, product name "Adwill RAD2500m / 12") was used on the exposed surface of the exposed adhesive layer. , The surface opposite to the surface to which the small pieces were attached in the above 6-inch silicon wafer was attached. Then, using a dicing device (manufactured by Disco Corporation, product name "DFD-6361"), an operation simulating dicing for cutting from the 6-inch silicon wafer side while supplying running water to the cutting portion under the following operating conditions is performed. gone.

<Operating conditions>
・ Dicing device: DFD-6361 manufactured by Disco Corporation
-Blade: NBC-2H 2050 27HECC manufactured by Disco Corporation
・ Blade width: 0.025 to 0.030 mm
・ Amount of cutting edge: 0.640 to 0.760 mm
・ Blade rotation speed: 50,000 rpm
・ Cutting speed: 20 mm / sec
・ Blade height: 5mm
・ Running water supply: 1.0 L / min
・ Running water temperature: Room temperature ・ Cut size: 10mm × 10mm
The above "blade height: 5 mm" means that the distance between the blade and the 6-inch silicon wafer is 5 mm, and as is clear from this, in the above operation, the 6-inch silicon wafer by the blade is used. No disconnection was performed.

After the completion of dicing, the presence or absence of the adhesive derived from the above-mentioned small pieces remaining on the silicon wafer was confirmed, and the removability of the adhesive was evaluated based on the following criteria. The results are shown in Table 3.
〇: No adhesive remained.
X: At least a part of the adhesive remained.

[Test Example 4] (Evaluation of water infiltration)
The release sheet was peeled off from the work processing sheet manufactured in Examples and Comparative Examples, and a tape mounter (manufactured by Lintec Corporation, product name "Adwill RAD2500m / 12") was used on the exposed surface of the exposed adhesive layer. A polished surface of a 6-inch silicon wafer (thickness: 150 μm) polished by 2000 was attached. Subsequently, using a dicing device (manufactured by Disco Corporation, 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 Corporation
-Blade: NBC-2H 2050 27HECC manufactured by Disco Corporation
・ Blade width: 0.025 to 0.030 mm
・ Amount of cutting edge: 0.640 to 0.760 mm
・ Blade rotation speed: 50,000 rpm
・ Cutting speed: 20 mm / sec
-Cut depth: 15 μm from the surface of the work processing sheet on the adhesive layer side
・ Running water supply: 1.0 L / min
・ Running water temperature: Room temperature ・ Cut size: 10mm × 10mm

After the completion of dicing, all the obtained chips are removed from the work processing sheet, and the surface of the work processing sheet on the adhesive layer side is a digital microscope (manufactured by KEYENCE, product name "VHX-1000", magnification: 500). The water infiltration at the interface between the chip and the work sheet was evaluated based on the following criteria. The results are shown in Table 3.
〇: There was no trace of water infiltration on the surface of the work sheet on the adhesive layer side.
X: There was a trace of water infiltration on the surface of the work sheet on the adhesive layer side.

The details of the abbreviations and the like shown in Table 1 are as follows.
BA: Butyl acrylate MMA: Methyl methacrylate DMAA: Dimethylacrylamide ACMO: Acryloylmorpholine MA: Methyl acrylate 2MEA: 2-methoxyethyl acrylate MTG: methoxyethylene glycol acrylate HEA: 2-Hydroxyethyl acrylate MOI: Methacryloyl Oxyethyl isocyanate

As can be seen from Table 3, the work processing sheet obtained in the examples was able to satisfactorily remove the adhesive by running water and to satisfactorily suppress the infiltration of water.

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

Claims (6)

A work processing sheet including a base material and an adhesive layer laminated on one side of the base material.
The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive.
The water contact angle of the surface of the pressure-sensitive adhesive layer opposite to the substrate is 50 ° or more and 80 ° or less.
The adhesive force of the work processing sheet to the silicon wafer is set to F1, the work processing sheet is immersed in distilled water at 23 ° C. for 12 hours, and further dried at 23 ° C. for 24 hours. When the adhesive force to the wafer is F2, the following formula (1)
Adhesive strength reduction rate (%) = {(F1-F2) / F1} x 100 ... (1)
A work processing sheet characterized in that the reduction rate of the adhesive strength calculated from the above is 20% or more and 50% or less. The work processing sheet according to claim 1, wherein the adhesive strength F1 is 1000 mN / 25 mm or more and 10,000 mN / 25 mm or less. The work processing sheet according to claim 1 or 2, wherein the adhesive strength F2 is 900 mN / 25 mm or more and 8000 mN / 25 mm or less. The active energy ray-curable pressure-sensitive adhesive has methyl acrylate, 2-methoxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate and methoxyethylene glycol (meth) acrylate as the monomer units constituting the polymer. The work processing according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive is formed from a pressure-sensitive adhesive composition containing an acrylic copolymer containing at least one selected from the above. Sheet. The work processing sheet according to any one of claims 1 to 4, wherein the dicing sheet is used. The bonding step of bonding the work to the surface of the pressure-sensitive adhesive layer of the work processing sheet according to any one of claims 1 to 5, which is opposite to the base material.
A processing process for obtaining a processed work laminated on the work processing sheet by processing the work on the work processing sheet, and a processing process.
An irradiation step of irradiating the pressure-sensitive adhesive layer with active energy rays to cure the pressure-sensitive adhesive layer and reducing the adhesive force of the work processing sheet to the processed work.
A method for manufacturing a processed work, which comprises a separation step of separating the processed work from the work processing sheet after irradiation with active energy rays.