JP7382690B2 - Workpiece processing sheet - Google Patents

Description

The present invention relates to a workpiece processing sheet that can be suitably used for dicing.

Semiconductor wafers such as silicon and gallium arsenide and various packages (hereinafter referred to collectively as "works") are manufactured in large diameter states, and these are made into small element pieces (hereinafter referred to as "chips"). ) are cut and separated (diced) and individually separated (picked up), and then transferred to the next process, a mounting process. At this time, the workpiece such as a semiconductor wafer is attached to a workpiece processing sheet including a base material and an adhesive layer, and is subjected to the steps of dicing, cleaning, drying, expanding, picking up, and mounting. Such a sheet for processing a workpiece is required to have performance that allows the workpiece to be held well on the sheet during processing, while also being able to easily separate the processed workpiece from the sheet.

The chips obtained as described above may then be subjected to heat treatment. For example, the chip may be subjected to treatments such as vapor deposition, sputtering, and baking for dehumidification. Furthermore, if the chip is expected to be used in a high-temperature environment, a heating test may be conducted to confirm reliability under such an environment. Usually, these heat treatments are performed with the obtained chip placed on a heating tray.

In recent years, it has been considered to perform the above-described heat treatment of chips on a workpiece processing sheet. In other words, it has been considered that after dicing a workpiece on a workpiece processing sheet, heat treatment is performed on the chips while the chips are placed on the workpiece processing sheet without transferring the obtained chips to a heating tray. There is. In this case, it becomes possible to simplify the process.

Patent Documents 1 to 3 disclose pressure-sensitive adhesive sheets that are intended to be subjected to the heat treatment described above. In particular, the adhesive sheet disclosed in Patent Document 1 has a base material layer and an adhesive layer made of a radiation-curable adhesive, and the adhesive layer has an adhesive force of 0.5 N/ to SUS304 after lamination. The layer has a thickness of 20 mm or more, is hardened by stimulation received until the resin sealing process is completed, and has a peeling force against the package of 2.0 N/20 mm or less. Furthermore, in the adhesive sheet disclosed in Patent Document 2, the adhesive layer is formed from an adhesive composition containing a predetermined adhesive component and a predetermined tetrazole compound. Furthermore, in the adhesive sheet disclosed in Patent Document 3, an adhesive layer containing a predetermined acrylic polymer, an energy beam polymerizable oligomer, a predetermined polymerization initiator, and a crosslinking agent is provided on a heat-resistant base material. An adhesive layer made of a forming material is formed.

Patent No. 5144634 Patent No. 5555578 Patent No. 5565173

However, when heat treatment of chips as described above is performed on a conventional workpiece processing sheet, heating improves the adhesion of the workpiece processing sheet to the chips. There was a problem that it became impossible to pick up the image well. Such problems could not be satisfactorily solved even by using pressure-sensitive adhesive sheets having a predetermined heat resistance as disclosed in Patent Documents 1 to 3.

The present invention has been made in view of the above-mentioned circumstances, and although it exhibits sufficient adhesion to the workpiece when processing the workpiece, it does not adhere to the workpiece after heat treatment. An object of the present invention is to provide a sheet for workpiece processing that can effectively separate .

In order to achieve the above object, the present invention first provides a workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, wherein the adhesive layer is activated. It is composed of an energy ray-curable adhesive, and the adhesive strength of the workpiece processing sheet to the silicon wafer is set to F0, and the laminate obtained by bonding the workpiece processing sheet to the silicon wafer is heated at 150° C. for 1 hour. Then, when the adhesive force of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer constituting the laminate with active energy rays is F2, the adhesive force F0 is Provided is a sheet for workpiece processing, characterized in that the adhesive force F2 is 600 mN/25 mm or more and 20000 mN/25 mm or less, and the ratio of the adhesive force F2 to the adhesive force F0 (F2/F0) is 0.66 or less (invention 1).

In the workpiece processing sheet according to the invention (invention 1), since the adhesive force F0 is within the above range, sufficient adhesive force can be exerted to the workpiece when the workpiece is processed. On the other hand, since the adhesive layer is composed of an active energy ray-curable adhesive and the adhesive force ratio (F2/F0) is within the above range, the workpiece after processing is stuck. Even if the sheet for workpiece processing is heated, by irradiating it with active energy rays afterward, the adhesion to the processed workpiece can be sufficiently reduced, thereby making it possible to maintain the processed workpiece in good condition. can be separated into

In the above invention (invention 1), after heating the workpiece processing sheet at 150°C for 1 hour, the Young's modulus of the adhesive layer at 23°C is E1, and the workpiece processing sheet is heated at 150°C for 1 hour. After heating and further irradiating the adhesive layer constituting the workpiece processing sheet with active energy rays, the Young's modulus at 23° C. of the adhesive layer is E2. It is preferable that the ratio of the Young's modulus E2 to the modulus E1 (E2/E1) is 13 or more (Invention 2).

In the above inventions (Inventions 1 and 2), the Young's modulus at 23°C of the adhesive layer in the workpiece processing sheet is E0, and the adhesive layer after heating the workpiece processing sheet at 150°C for 1 hour. When the Young's modulus of the layer at 23° C. is E1, the ratio of the Young's modulus E1 to the Young's modulus E0 (E1/E0) is preferably 2.0 or more (Invention 3).

Second, the present invention provides a workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, wherein the adhesive layer is made of an active energy ray-curable adhesive. The active energy ray curable adhesive has a glass transition temperature of -50°C or more and 10°C or less, and the active energy ray curable adhesive is an acrylic material containing a monomer having a polar group as a constituent monomer. Provided is a workpiece processing sheet characterized by containing a copolymer (Invention 4).

In the above invention (invention 4), the acrylic copolymer preferably has a functional group having active energy ray curability introduced into the side chain (invention 5).

In the above inventions (Inventions 1 to 5), a dicing sheet is preferable (Invention 6).

The workpiece processing sheet according to the present invention exhibits sufficient adhesion to the workpiece when processing the workpiece, and is capable of effectively separating the processed workpiece after undergoing heat treatment. can.

Embodiments of the present invention will be described below.
The workpiece processing sheet according to this embodiment includes a base material and an adhesive layer laminated on one side of the base material. Further, the adhesive layer is made of an active energy ray-curable adhesive.

1. Physical properties of workpiece processing sheet (1) Adhesive force In the workpiece processing sheet according to the present embodiment, the adhesive force F0 is 600 mN/25mm or more, where F0 is the adhesive force of the workpiece processing sheet to the silicon wafer. is preferable, particularly preferably 900 mN/25 mm or more, and even more preferably 1200 mN/25 mm or more. Further, the adhesive force F0 is preferably 20,000 mN/25 mm or less, particularly preferably 5,000 mN/25 mm or less, and even more preferably 3,000 mN/25 mm or less. Note that the adhesive force F0 refers to the initial adhesive force measured for a workpiece processing sheet that has not been subjected to treatments such as heating and active energy ray irradiation, which will be described later.

In the workpiece processing sheet according to the present embodiment, since the adhesive force F0 is within the above range, the workpiece can be satisfactorily held on the workpiece processing sheet. Therefore, during machining of a workpiece, it is possible to satisfactorily suppress movement or falling off of the workpiece after machining, even if an impact occurs due to machining, for example. In particular, when the adhesive force F0 is 600 mN/25 mm or more, it becomes easy to hold the work well during processing. On the other hand, when the adhesive force F0 is 20,000 mN/25 mm or less, when the workpiece processing sheet is irradiated with active energy rays, which will be described later, the adhesive force to the processed workpiece can be sufficiently reduced. This makes it easy to separate the processed workpiece from the workpiece processing sheet.

In the workpiece processing sheet according to this embodiment, after heating the laminate formed by bonding the workpiece processing sheet to a silicon wafer at 150°C for 1 hour, the adhesive layer constituting the laminate is further heated. When the adhesive force of the workpiece processing sheet to the silicon wafer after irradiation with active energy rays is F2, the ratio of the adhesive force F2 to the above-mentioned adhesive force F0 (F2/F0) is 0.66 or less. is preferable, particularly preferably 0.2 or less, and even more preferably 0.15 or less. When the ratio (F2/F0) is 0.66 or less, it becomes easy to achieve both the holding of the workpiece during processing and the separation of the processed workpiece after irradiation with active energy rays. In particular, even if the processed workpiece is pasted onto the workpiece processing sheet and the workpiece processing sheet is exposed to heat treatment, the processed workpiece can be separated well from the workpiece processing sheet. It becomes easy. Note that the lower limit of the ratio (F2/F0) is not particularly limited, but may be, for example, 0.01 or more.

In the workpiece processing sheet according to the present embodiment, the adhesive force F2 described above is preferably 1000 mN/25 mm or less, particularly preferably 500 mN/25 mm or less, and more preferably 150 mN/25 mm or less. . Moreover, it is preferable that the adhesive force F2 is 30 mN/25 mm or more. When the adhesive force F2 is within the above range, the ratio (F2/F0) can be easily adjusted within the above range.

In the workpiece processing sheet according to the present embodiment, the adhesive force of the workpiece processing sheet to the silicon wafer after heating the laminate formed by bonding the workpiece processing sheet to the silicon wafer at 150° C. for 1 hour is defined as F1. In this case, the adhesive force F1 is preferably 1000 mN/25 mm or more, particularly preferably 2300 mN/25 mm or more. Moreover, it is preferable that the adhesive force F1 is 5000 mN/25 mm or less. When the adhesive force F1 is within the above range, it becomes easy to adjust the ratio (F2/F0) to the above range.

Note that the details of the methods for measuring each of the adhesive forces F0, F1, and F2 described above are as described in the test examples described later.

(2) Young's Modulus In the workpiece processing sheet according to this embodiment, the Young's modulus of the adhesive layer at 23°C after heating the workpiece processing sheet at 150°C for 1 hour is E1, and the workpiece processing sheet is When E2 is the Young's modulus of the adhesive layer at 23°C after heating at 150°C for 1 hour and further irradiating the adhesive layer constituting the workpiece processing sheet with active energy rays. Furthermore, the ratio of the Young's modulus E2 to the Young's modulus E1 (E2/E1) is preferably 13 or more, particularly preferably 15 or more, and even more preferably 18 or more.

As mentioned above, the adhesive layer in this embodiment is composed of an active energy ray-curable adhesive. In general, components for achieving active energy ray curability that are present in active energy ray curable adhesives undergo a predetermined reaction when heated, and the curing of the adhesive progresses due to this. be. For example, when the above component is an acryloyl group, the carbon-carbon double bond in the acryloyl group may be cleaved by heating, and the polymerization reaction may proceed. In this way, when the reaction of the above-mentioned components progresses due to heating, further curing of the adhesive layer does not progress satisfactorily even if active energy rays are subsequently irradiated. However, in the workpiece processing sheet according to the present embodiment, if the ratio (E2/E1) is within the above range, the adhesive force can be favorably reduced by irradiation with active energy rays even after heat treatment. It becomes easier to do so. Thereby, it is possible to effectively suppress unintentional falling off of the processed workpiece before irradiation with active energy rays.

Note that the upper limit of the ratio (E2/E1) is not particularly limited, and may be, for example, 25 or less.

In the workpiece processing sheet according to the present embodiment, when the Young's modulus at 23° C. of the adhesive layer in the workpiece processing sheet is E0, the ratio (E1/E0) of the Young's modulus E1 to the Young's modulus E0 is , preferably 2.0 or more, particularly preferably 2.3 or more, and even more preferably 2.6 or more. Note that the above-mentioned Young's modulus E0 means the initial Young's modulus measured for the adhesive layer that has not been subjected to treatments such as heating or active energy ray irradiation.

Generally, when an adhesive is heated, it tends to soften and its adhesion to an adherend increases. However, in the workpiece processing sheet according to the present embodiment, if the ratio (E1/E0) is within the above range, the adhesive will not easily soften due to heating, and excessive improvement in adhesion due to heat treatment will occur. This makes it possible to effectively suppress it. As a result, after the adhesive layer is irradiated with active energy rays, the processed workpiece can be easily separated.

Note that the upper limit of the ratio (E1/E0) is not particularly limited, and may be, for example, 3.5 or less.

In the workpiece processing sheet according to the present embodiment, the above-mentioned Young's modulus E0 is preferably 2.0 MPa or more, particularly preferably 2.3 MPa or more, and more preferably 2.5 MPa or more. . Further, the Young's modulus E0 is preferably 15 MPa or less, particularly preferably 10 MPa or less, and even more preferably 5 MPa or less. When the Young's modulus E0 is within the above range, the ratio (E1/E0) can be easily adjusted within the above range.

In the workpiece processing sheet according to the present embodiment, the Young's modulus E1 described above is preferably 5.0 MPa or more, particularly preferably 6.0 MPa or more, and more preferably 7.0 MPa or more. . Further, the Young's modulus E1 is preferably 100 MPa or less, particularly preferably 50 MPa or less, and even more preferably 10 MPa or less. When the Young's modulus E1 is within the above range, the ratio (E2/E1) and the ratio (E1/E0) can be easily adjusted to the above ranges.

In the workpiece processing sheet according to the present embodiment, the Young's modulus E2 described above is preferably 100 MPa or more, particularly preferably 130 MPa or more, and even more preferably 140 MPa or more. Further, the Young's modulus E2 is preferably 300 MPa or less, particularly preferably 250 MPa or less, and even more preferably 200 MPa or less. When the Young's modulus E2 is within the above range, the ratio (E2/E1) can be easily adjusted to the above range.

Note that the details of the method for measuring each of the Young's moduli E0, E1, and E2 described above are as described in the test examples described later.

2. Constituent members of workpiece processing sheet (1) Base material In the workpiece processing sheet according to the present embodiment, the base material exhibits a desired function in the process of using the workpiece processing sheet, and preferably hardens the adhesive layer. It is not particularly limited as long as it exhibits good transparency to the active energy rays irradiated for the purpose and has a predetermined heat resistance.

For example, the base material is preferably a resin film mainly made 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 film and other ethylene-(meth)acrylate ester copolymer films; polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene Polyolefin films such as film, ethylene-norbornene copolymer film, norbornene resin film, cycloolefin resin film; Polyvinyl chloride film such as polyvinyl chloride film, vinyl chloride copolymer film; Polyethylene terephthalate film, polybutylene terephthalate Polyester films such as polycyclohexylene dimethylene terephthalate and polyethylene naphthalate; (meth)acrylic ester copolymer films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films; polyphenylene sulfide films, etc. Can be mentioned. 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 crosslinked films and ionomer films may also be used. Further, the base material may be a laminated film formed by laminating a plurality of the above-mentioned films. In this laminated film, the materials constituting each layer may be the same or different. Among the above-mentioned films, as a base material, annealed polyester films, heat-resistant polyester films, polycarbonate films, polyphenylene sulfide films, and cycloolefins are recommended because they have excellent transparency to active energy rays and heat resistance. Preferably, a resin film is used. In addition, "(meth)acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

The base material 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 that allows the base material to exhibit the desired function.

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

Although the thickness of the base material can be appropriately set depending on the method in which the workpiece processing sheet is used, it is usually preferably 20 μm or more, particularly preferably 25 μm or more. Further, the thickness is usually preferably 450 μm or less, particularly preferably 300 μm or less.

(2) Adhesive Layer In the workpiece processing sheet according to the present embodiment, the adhesive layer is composed of an active energy ray-curable adhesive. Since the adhesive layer is composed of an active energy ray-curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, and the adhesive force of the workpiece processing sheet to the adherend can be reduced. . This makes it possible to easily separate the processed workpiece from the workpiece processing sheet.

Moreover, it is preferable that the adhesive layer in this embodiment is capable of achieving the above-mentioned adhesive strength. From this point of view, the adhesive layer in the present embodiment is such that the active energy ray-curable adhesive constituting the adhesive layer has a glass transition temperature of -50°C or more and 10°C or less, and is active energy ray-curable. It is preferable that the adhesive contains an acrylic copolymer containing a monomer having a polar group as a constituent monomer. By including an adhesive layer composed of such an active energy ray-curable adhesive, the workpiece processing sheet can easily achieve the adhesive strength described above.

From the viewpoint of making it easier for the workpiece processing sheet to achieve the above-mentioned adhesive strength, the glass transition temperature is particularly preferably -20°C or higher, and more preferably -15°C or higher. Further, from the same viewpoint, the glass transition temperature is preferably 5.0°C or lower, and more preferably 3.0°C or lower. Note that the details of the method for measuring the glass transition temperature are as described in the test examples described later.

The active energy ray-curable adhesive constituting the adhesive layer may be composed mainly of a polymer that is curable with active energy rays, or may be a polymer that is not curable with active energy rays (a polymer that is curable with active energy rays). The main component may be a mixture of a polymer having no active energy ray-curable group) and a monomer and/or oligomer having at least one active energy ray-curable group.

First, a case where the active energy ray curable adhesive has a polymer having active energy ray curability as a main component will be described below.

The polymer having active energy ray curability is a (meth)acrylic acid ester (co)polymer (A) (hereinafter referred to as (Sometimes referred to as "active energy ray-curable polymer (A).") is preferable. 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 bonded to the functional group. Preferably, it is obtained by reaction.

The above-mentioned functional group-containing monomer is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, an amide group, a benzyl group, or a glycidyl group in the molecule. Among these, it is preferable to use a monomer containing a hydroxy group as a functional group (hydroxy 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, Examples include 3-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. Among these, it is preferable to use 2-hydroxyethyl acrylate. Note that these 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 amide 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, particularly preferably 5% by mass or more, and more preferably 10% by mass or more of the structural unit derived from the functional group-containing monomer. It is preferable to do so. Further, the acrylic copolymer (a1) preferably contains a structural unit derived from the functional group-containing monomer in an amount of 35% by mass or less, particularly preferably 30% by mass or less. When the acrylic copolymer (a1) contains the functional group-containing monomer in the above range, it becomes easy to form the desired active energy ray-curable polymer (A).

As described above, the acrylic copolymer (a1) preferably contains a monomer having a polar group (polar group-containing monomer) as a monomer unit constituting the polymer. This improves the polarity of the resulting active energy ray-curable adhesive, making it easier to achieve the adhesive strength described above.

Examples of polar group-containing monomers include acryloylmorpholine, isobornyl acrylate, methyl methacrylate, vinyl acetate, benzyl acrylate, glycidyl methacrylate, etc. Among these, acryloylmorpholine or isobornyl acrylate is particularly used. It is preferable to do so.

The acrylic copolymer (a1) preferably contains 3.0% by mass or more, particularly preferably 5.0% by mass or more, of structural units derived from the above polar group-containing monomer, and more preferably 8.0% by mass or more, and more preferably 5.0% by mass or more, The content is preferably .0% by mass or more. Further, the acrylic copolymer (a1) preferably contains 12.0% by mass or less of a structural unit derived from the polar group-containing monomer. When the acrylic copolymer (a1) contains the polar group-containing monomer in the above range, the polarity of the resulting active energy ray-curable adhesive can be effectively improved, thereby achieving the above-mentioned adhesive strength. becomes easier to achieve.

In addition, the acrylic copolymer (a1) may contain a monomer (Tg adjustment monomer) for adjusting the glass transition temperature (Tg) of the active energy ray-curable adhesive as a monomer unit constituting the polymer. is also preferable. As a result, the resulting active energy ray-curable adhesive tends to have the above-mentioned glass transition temperature (Tg). Examples of preferable monomers that also serve as Tg adjusting monomers include those mentioned above as examples of polar group-containing monomers, and among them, it is particularly preferable to use acryloylmorpholine or isobornyl acrylate.

The glass transition temperature of the Tg adjusting monomer described above is preferably 30°C or higher, particularly preferably 50°C or higher, and even more preferably 90°C or higher. Further, the glass transition temperature of the Tg adjusting monomer is preferably 200°C or lower, particularly preferably 180°C or lower, and even more preferably 150°C or lower. By using a Tg adjusting monomer having a glass transition temperature within these ranges, it becomes easy to adjust the glass transition temperature of the active energy ray-curable adhesive to the above range. In addition, in this specification, the glass transition temperature of a monomer shall refer to the glass transition temperature measured for a homopolymer composed only of the monomer.

Further, the solubility parameter (SP value) of the above-mentioned Tg adjusting monomer is preferably 9.8 or more, particularly preferably 9.9 or more, and even more preferably 10.0 or more. When the SP value of the Tg adjustment monomer is 9.8 or more, the adhesive force of the workpiece processing sheet can be easily adjusted within the above-mentioned range, and in particular, the initial adhesive force F0 can be easily adjusted within the above-mentioned range. becomes. This makes it easier to hold the workpiece on the workpiece processing sheet during processing. Note that the upper limit of the solubility parameter (SP value) is not particularly limited, and may be, for example, 11 or less.

The acrylic copolymer (a1) preferably contains 3.0% by mass or more, particularly preferably 5.0% by mass or more, of the structural unit derived from the above-mentioned Tg adjusting monomer, and more preferably 8.0% by mass or more. The content is preferably 0% by mass or more. Further, the acrylic copolymer (a1) preferably contains 12.0% by mass or less of a structural unit derived from the Tg adjusting monomer. When the acrylic copolymer (a1) contains the Tg adjusting monomer in the above range, the glass transition temperature of the resulting active energy ray-curable adhesive can be easily adjusted to the above range.

For the acrylic copolymer (a1), it is also preferable to use a (meth)acrylic acid alkyl ester monomer in which the alkyl group has 1 to 20 carbon atoms as a monomer unit constituting the polymer. As such a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkyl ester monomer in which the alkyl group has 1 to 18 carbon atoms is particularly preferred. Moreover, from the viewpoint of easily obtaining a pressure-sensitive adhesive having excellent heat resistance, a (meth)acrylic acid alkyl ester monomer in which the alkyl group has 8 or more carbon atoms is preferable. Preferred examples of (meth)acrylic acid alkyl ester monomers in which the alkyl group has 1 to 20 carbon atoms include methyl methacrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and n-(meth)acrylate. Examples include butyl, 2-ethylhexyl (meth)acrylate, and the like. These may be used alone or in combination of two or more.

The acrylic copolymer (a1) preferably contains 50% by mass or more of a structural unit derived from the above-mentioned (meth)acrylic acid alkyl ester monomer whose alkyl group has 1 to 20 carbon atoms, particularly The content is preferably 60% by mass or more, and more preferably 70% by mass or more. Further, the acrylic copolymer (a1) may contain 99% by mass or less of a structural unit derived from the above-mentioned (meth)acrylic acid alkyl ester monomer in which the alkyl group has 1 to 20 carbon atoms. The content is preferably 95% by mass or less, and more preferably 90% by mass or less.

The acrylic copolymer (a1) can preferably be obtained by copolymerizing the above-described monomers or their derivatives in a conventional manner. A monomer (monomer containing an alicyclic structure), dimethyl acrylamide, vinyl formate, styrene, etc. may be copolymerized.

Examples of the alicyclic structure-containing monomers include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclo(meth)acrylate. Examples include pentenyl, dicyclopentenyloxyethyl (meth)acrylate, and the like. These may be used alone or in combination of two or more.

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

The functional group that the unsaturated group-containing compound (a2) has can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit that the acrylic copolymer (a1) has. For example, when the functional group of the acrylic copolymer (a1) is a hydroxy group, an amino group, or an amide group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group; When the functional group possessed by the copolymer (a1) is a glycidyl group, the functional group possessed by 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 1, preferably 1 to 6, more preferably 1 to 4 active energy ray polymerizable carbon-carbon double bonds in one molecule. It is. Specific examples of such unsaturated group-containing compounds (a2) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-( (bisacryloyloxymethyl)ethyl isocyanate; an 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 (meth)acrylic acid. Acryloyl monoisocyanate compound obtained by reaction with acid hydroxyethyl; 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, and even more preferably It is used in a proportion of 70 mol% or more. Further, 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 of the acrylic copolymer (a1), and 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 reaction between the functional group of the acrylic copolymer (a1) and the functional group of the unsaturated group-containing compound (a2) is performed. Depending on the combination, reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected. As a result, the functional groups present in the acrylic copolymer (a1) and the functional groups in the unsaturated group-containing compound (a2) react, and the unsaturated groups in the acrylic copolymer (a1) react with each other. It is introduced into the side chain, and an 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 more preferably 200,000 or more. It is preferable to have one. Further, the weight average molecular weight (Mw) is preferably 1.5 million or less, particularly preferably 1 million or less. Note that the weight average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC method) in terms of standard polystyrene.

Even when the active energy ray curable adhesive is mainly composed of a polymer having active energy ray curable properties such as the active energy ray curable polymer (A), the active energy ray curable adhesive It may further contain a line-curable monomer and/or oligomer (B).

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 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 Examples include polyfunctional acrylic esters such as glycol di(meth)acrylate and dimethylol tricyclodecane di(meth)acrylate, polyester oligo(meth)acrylate, and polyurethane oligo(meth)acrylate.

When blending an active energy ray curable monomer and/or oligomer (B) with the active energy ray curable polymer (A), the active energy ray curable monomer and/or oligomer (B) in the active energy ray curable adhesive. Alternatively, the content of the oligomer (B) is preferably more than 0 parts by mass, particularly preferably 60 parts by mass or more, based on 100 parts by mass of the active energy ray-curable polymer (A). Further, the content is preferably 250 parts by mass or less, particularly preferably 200 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

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

The photopolymerization initiator (C) in this embodiment preferably has a 5% weight loss temperature of 200°C or higher, particularly preferably 210°C or higher, and even more preferably 220°C or higher. By using a photopolymerization initiator (C) that exhibits a 5% weight loss temperature of 200°C or higher, the adhesive strength of the sheet for workpiece processing can be easily adjusted within the above-mentioned range. It becomes easy to adjust the adhesive force F2 after aging to within the above-mentioned range. Thereby, even when heat treatment is performed, the processed workpiece can be easily separated from the workpiece processing sheet. The upper limit of the 5% weight loss temperature is not particularly limited, and may be, for example, 300°C or lower, particularly 280°C or lower, or even 250°C or lower. Note that the details of the method for measuring the 5% weight loss temperature are as described in the Examples described later.

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, benzoin methyl benzoate, benzoin dimethyl ketal, 2, 4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, 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, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1- Examples include on. Among these, it is preferable to use 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one. These may be used alone or in combination of two or more.

The photopolymerization initiator (C) is an active energy ray curable polymer (A) (when blending an active energy ray curable monomer and/or oligomer (B), an active energy ray curable polymer (A)). ) and the active energy ray-curable monomer and/or oligomer (B) in an amount of 0.1 part by mass or more, particularly 0.5 part by mass or more based on 100 parts by mass) of the total amount of active energy ray-curable monomer and/or oligomer (B). preferable. In addition, the photopolymerization initiator (C) is an active energy ray curable polymer (A) (in the case of blending an active energy ray curable monomer and/or oligomer (B), an active energy ray curable polymer It is preferably used in an amount of 10 parts by mass or less, particularly 6 parts by mass or less, based on 100 parts by mass of the total amount of (A) and the active energy ray-curable monomer and/or oligomer (B).

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

Examples of the active energy ray non-curable polymer component or oligomer component (D) include polyacrylic esters, polyesters, polyurethanes, polycarbonates, polyolefins, etc., and polymers or oligomers having a weight average molecular weight (Mw) of 3,000 to 2,500,000. Oligomers are preferred. By blending the component (D) into an active energy ray-curable adhesive, it is possible to improve the adhesiveness and peelability before curing, the strength after curing, the adhesiveness with other layers, the storage stability, etc. The blending amount of the component (D) is not particularly limited, and is appropriately determined within a range of more than 0 parts by mass and 50 parts by mass or less based on 100 parts by mass of the active energy ray-curable polymer (A).

As the crosslinking agent (E), a polyfunctional compound that is reactive with the functional groups of the active energy ray-curable polymer (A) and 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, Examples include reactive phenol resins.

The blending amount of the crosslinking agent (E) is preferably 0.01 parts by mass or more, particularly preferably 1 part by mass or more, based on 100 parts by mass of the active energy ray-curable polymer (A). Further, the amount of the crosslinking agent (E) to be blended is preferably 20 parts by mass or less, particularly preferably 17 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

Next, regarding the case where the active energy ray curable adhesive mainly contains a mixture of an active energy ray non-curable polymer component and a monomer and/or oligomer having at least one active energy ray curable group, This will be explained 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 active energy ray-curable group, the same monomers and/or oligomers as the above-mentioned 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 part by mass based on 100 parts by mass of the active energy ray non-curable polymer component. The amount of the monomer and/or oligomer having at least three active energy ray-curable groups is preferably 1 part by mass or more, particularly preferably 60 parts by mass or more. Further, the blending ratio is preferably 200 parts by mass or less of a monomer and/or oligomer having at least one active energy ray curable group 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, a photopolymerization initiator (C) and a crosslinking agent (E) can be appropriately blended in the same manner as above.

The thickness of the adhesive layer is preferably 1 μm or more, more preferably 5 μm or more. Further, the thickness is preferably 50 μm or less, and more preferably 40 μm or less. When the thickness of the adhesive layer is within the above range, the adhesive force described above can be easily achieved.

(3) Release sheet In the workpiece processing sheet according to this embodiment, until the surface of the adhesive layer opposite to the base material (hereinafter sometimes referred to as "adhesive surface") is attached to the workpiece, A release sheet may be laminated on the surface for the purpose of protecting the surface. The structure of the release sheet is arbitrary, and an example thereof is a plastic film subjected to release treatment using 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, silicone-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among these, silicone-based is preferred because it is inexpensive and provides stable performance. 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 workpiece 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 workpiece processing sheet according to the present embodiment can be used as a dicing/die bonding sheet by being provided with an adhesive layer as described above. In such workpiece processing sheets, the workpiece is pasted on the opposite side of the adhesive layer from the adhesive layer, and the adhesive layer is diced together with the workpiece, so that the individualized adhesive layers are laminated. You can get the chips. The chip can be easily fixed to the object on which the chip is to be mounted, by means of the individualized adhesive layer. Examples of the material constituting the adhesive layer described above include those containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, and those containing a B-stage (semi-cured) thermosetting adhesive component. It is preferable to use

Further, in the workpiece 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 workpiece processing sheet according to this embodiment can be used as a protective film forming and dicing sheet. In such a sheet for workpiece processing, a workpiece 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 workpiece to form individualized protective films. A chip with stacked layers can be obtained. The work preferably has a circuit formed on one side, and in this case, a protective film forming layer is usually laminated on the opposite side to the side on which the circuit is formed. By curing the separated 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.

Although it is preferable that the workpiece processing sheet according to the present embodiment satisfies the conditions described above regarding adhesive strength, when the above-mentioned adhesive layer or protective film forming layer is laminated to the adhesive layer, In this case, the adhesive layer before these layers are laminated has only to satisfy the above-mentioned adhesive strength.

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

Lamination of the adhesive layer on one side of the base material can be performed by a known method. For example, it is preferable to transfer the adhesive layer formed on the release sheet to one side of the base material. In this case, a coating liquid containing the adhesive composition constituting the adhesive layer and, if desired, a solvent or dispersion medium is prepared, and the release-treated surface of the release sheet (hereinafter sometimes referred to as "release surface") is prepared. .) The coating solution is applied onto the adhesive layer using a die coater, curtain coater, spray coater, slit coater, knife coater, etc. to form a coating film, and the adhesive layer is formed by drying the coating film. be able to. The coating liquid is not particularly limited in its properties as long as it can be applied, and may contain components for forming the adhesive layer as a solute or as a dispersoid. The release sheet in this laminate may be released as a process material, or may be used to protect the adhesive surface of the adhesive layer until the workpiece processing sheet is attached to the workpiece.

When the coating solution for forming the adhesive layer contains a crosslinking agent, the drying conditions (temperature, time, etc.) described above or by providing a separate heat treatment can improve the A crosslinking reaction between the active energy ray curable polymer (A) or the active energy ray non-curable polymer and the crosslinking agent may be allowed to proceed to form a crosslinked structure at a desired density within the adhesive layer. In order to allow this crosslinking reaction to proceed sufficiently, after laminating the adhesive layer on the base material by the method described above, the obtained workpiece processing sheet is placed in an environment of, for example, 23°C and 50% relative humidity for several days. Curing such as leaving it still may be performed.

Instead of transferring the adhesive layer formed on the release sheet to one side of the base material as described above, the adhesive layer may be formed directly on the base material. 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 base material to form a coating film, and drying the coating film.

4. How to use the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used for processing a workpiece. That is, after the adhesive surface of the workpiece processing sheet according to this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet. Depending on the processing, the workpiece processing sheet according to this embodiment can be used as a back grinding sheet, a dicing sheet, an expanded sheet, a pickup sheet, etc. Here, examples of the work include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.

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

When the processing of the workpiece is completed on the workpiece processing sheet according to this embodiment and the processed workpiece is to be separated from the workpiece processing sheet, the adhesive layer on the workpiece processing sheet should be It is preferable to irradiate active energy rays. As a result, the adhesive layer is cured, and the adhesion of the workpiece processing sheet to the processed workpiece is favorably reduced, and the separation of the processed workpiece is facilitated.

As the above-mentioned active energy ray, for example, electromagnetic waves or charged particle beams having energy quantum can be used, and specifically, ultraviolet rays, electron beams, etc. can be used. In particular, ultraviolet light is preferred because it is easy to handle. Irradiation of ultraviolet rays can be performed using a high-pressure mercury lamp, a xenon lamp, an LED, etc., and the amount of irradiation of ultraviolet rays preferably has an illuminance of 50 mW/cm ² or more and 1000 mW/cm ² or less. Further, the amount of light is preferably 50 mJ/cm ² or more, particularly preferably 80 mJ/cm ² or more, and even more preferably 200 mJ/cm ² or more. Further, the amount of light is preferably 10,000 mJ/cm ² or less, particularly preferably 5,000 mJ/cm ² or less, and even more preferably 2,000 mJ/cm ² or less. On the other hand, the electron beam irradiation can be performed using an electron beam accelerator or the like, and the electron beam irradiation amount is preferably 10 krad or more and 1000 krad or less.

In the workpiece processing sheet according to the present embodiment, the adhesive force F0 is within the above-mentioned range, so that when processing the workpiece, sufficient adhesive force is exerted to the workpiece, and the workpiece and the processed workpiece are Problems such as movement and falling off can be effectively suppressed. Furthermore, since the adhesive layer is composed of an active energy ray-curable adhesive and the adhesive force ratio F2/F0 is within the above-mentioned range, the workpiece processing sheet with the processed workpiece attached can be Even if the material is heated, by irradiating it with active energy rays, the adhesion to the processed workpiece can be sufficiently reduced, thereby making it possible to pick up the processed workpiece well. can. Therefore, the workpiece processing sheet according to the present embodiment is suitable for applications where the workpiece processing sheet is exposed to a high-temperature environment with a workpiece or a processed workpiece attached to the workpiece processing sheet. can be used. In particular, the workpiece processing sheet according to the present embodiment is such that silicon wafers or the like are diced on the workpiece processing sheet, and the resulting chips are subjected to heat treatment on the workpiece processing sheet. It is suitable for use in various applications.

When the workpiece processing sheet according to the present embodiment is used as a dicing sheet and is also used for performing heat treatment with chips pasted on the workpiece processing sheet after dicing, the heating conditions include, for example, heating The temperature is preferably 40°C or higher, particularly preferably 80°C or higher, and even more preferably 100°C or higher. Further, the heating temperature is preferably 150°C or lower, particularly preferably 130°C or lower, and even more preferably 120°C or lower. Further, the heating time is preferably, for example, 3 minutes or more, particularly preferably 10 minutes or more, and even more preferably 30 minutes or more. Further, the heating time is preferably 60 minutes or less, particularly preferably 50 minutes or less, and even more preferably 40 minutes or less. The workpiece processing sheet according to this embodiment can separate chips well even when heated under the conditions described above.

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 intended 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 base material and the adhesive layer, or on the surface of the base material opposite to the adhesive layer.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

[Example 1]
(1) Preparation of adhesive composition Acrylic copolymer obtained by copolymerizing 70 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of acryloylmorpholine, and 20 parts by mass of 2-hydroxyethyl acrylate. and methacryloyloxyethyl isocyanate (MOI) in an amount of 90 mol % based on the number of moles of 2-hydroxyethyl acrylate in the acrylic copolymer to obtain an active energy ray-curable polymer. The weight average molecular weight (Mw) of this active energy ray-curable polymer was measured by the method described below and was found to be 830,000.

100 parts by mass of the obtained active energy ray-curable polymer (in terms of solid content, the same hereinafter) and an aliphatic isocyanate having hexamethylene diisocyanate as a crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., product name "Coronate HX") 1.2 parts by mass and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1- as a photoinitiator. On (manufactured by BASF, product name "Omnirad 127", 5% weight loss temperature: 220° C.) was mixed with 1.2 parts by mass in a solvent to obtain an adhesive composition. The 5% weight loss temperature of the photopolymerization initiator was measured using a differential thermal/thermogravimetric simultaneous measuring device (manufactured by SHIMADZU, product name "DTG-60") at a heating rate of 5°C/5°C from room temperature to 300°C. It was measured by heating for 30 minutes.

(2) Formation of adhesive layer On the release surface of a release sheet (manufactured by Lintec, product name "SP-PET381031"), which is made of a 38 μm thick polyethylene terephthalate film with a silicone release agent layer formed on one side. The above adhesive composition was applied, dried by heating, and then cured for 7 days at 23° C. and 50% RH to form a 5 μm thick adhesive layer on the release sheet.

(3) Preparation of sheet for workpiece processing The surface of the adhesive layer formed in step (2) above, opposite to the release sheet, and the heat-resistant polyester film (manufactured by Kurabo Industries, Ltd.) with a thickness of 75 μm as a base material , product name ``Torsena'') was attached to one side to obtain a workpiece processing sheet.

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

[Examples 2 to 8 and Comparative Examples 1 to 4]
A workpiece processing sheet was prepared in the same manner as in Example 1, except that the composition and weight average molecular weight of the acrylic copolymer were changed as shown in Table 1, and the composition of the adhesive composition was changed as shown in Table 2. was manufactured.

[Test Example 1] (Measurement of glass transition temperature of adhesive)
A laminate of adhesive layers having a thickness of 800 μm was produced by laminating a plurality of adhesive layers of the workpiece processing sheets manufactured in Examples and Comparative Examples. Subsequently, a sample for measurement was obtained by punching out this adhesive layer laminate into a circle with a diameter of 10 mm. The measurement sample was measured using a dynamic viscoelasticity measurement device (manufactured by TA Instruments, product name "ARES") at a frequency of 1 Hz, a measurement temperature range of -50 to 150°C, and a heating rate of 3°C. tan δ was measured under the condition of /min, and the temperature at the top of the peak was defined as Tg. The results are shown in Table 3.

[Test Example 2] (Measurement of adhesive strength)
The workpiece processing sheets produced in Examples and Comparative Examples were cut into strips with a width of 25 mm. The release sheet was peeled off from the obtained strip-shaped workpiece processing sheet, and the exposed adhesive surface of the adhesive layer was exposed to the mirror surface of a mirror-finished silicon wafer at a temperature of 23°C and a relative humidity of 50%. They were laminated using a 2 kg rubber roller in an environment, and left to stand for 20 minutes to prepare a sample for measurement.

The obtained measurement sample was processed into a workpiece from a silicon wafer using a universal tensile tester (manufactured by Orientec, product name: "Tensilon UTM-4-100") at a peeling speed of 300 mm/min and a peeling angle of 180°. The adhesive force (mN/25 mm) to a silicon wafer was measured by peeling off the sheet and using a 180° peeling method according to JIS Z0237:2009. The adhesive strength thus obtained is shown in Table 3 as adhesive strength F0.

Further, a measurement sample obtained in the same manner as above was heated at 150° C. for 1 hour using an oven. The adhesive force (mN/25 mm) to a silicon wafer was measured for the heated measurement sample in the same manner as above. The adhesive strength thus obtained is shown in Table 3 as adhesive strength F1.

Further, a measurement sample obtained in the same manner as above was heated at 150° C. for 1 hour using an oven. Further, the adhesive layer was irradiated with ultraviolet rays through the base material under the following conditions. Regarding this measurement sample, the adhesive force (mN/25 mm) to a silicon wafer was measured in the same manner as above. The adhesive strength thus obtained is shown in Table 3 as adhesive strength F2.
<Ultraviolet irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 230mW/cm ² , light intensity 190mJ/cm ²
・UV illuminance/light meter uses “UVPF-A1” manufactured by Eye Graphics.

Furthermore, from the three types of adhesive forces obtained as described above, the ratio of the adhesive force F2 to the adhesive force F0 (F2/F0) and the ratio of the adhesive force F0 to the adhesive force F1 (F0/F1) were calculated, respectively. These results are shown in Table 3.

[Test Example 3] (Measurement of Young's modulus of adhesive)
A plurality of laminates of an adhesive layer and a release sheet produced in the same manner as in the above step (2) of Example 1 were prepared for each of Examples and Comparative Examples. Then, by laminating a predetermined number of adhesive layers in the laminate, a measuring adhesive layer sample consisting of an adhesive layer with a thickness of 200 μm was produced.

The obtained adhesive layer sample for measurement was tested using a universal tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS") at a speed of 200 mm/min at a distance of 30 mm between chucks in an environment of 23°C. Young's modulus (MPa) was determined from the resulting stress-strain curve. The results obtained are shown in Table 3 as Young's modulus E0.

Moreover, the adhesive layer sample for measurement obtained in the same manner as above was heated at 150° C. for 1 hour using an oven. The Young's modulus (MPa) of the heated measurement adhesive layer sample was determined in the same manner as above. The results obtained are shown in Table 3 as Young's modulus E1.

Moreover, the adhesive layer sample for measurement obtained in the same manner as above was heated at 150° C. for 1 hour using an oven. Furthermore, the measurement adhesive layer sample after heating was irradiated with ultraviolet rays under the following conditions. The Young's modulus (MPa) of this measurement adhesive layer sample was determined in the same manner as above. The results obtained are shown in Table 3 as Young's modulus E2.
<Ultraviolet irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 230mW/cm ² , light intensity 580mJ/cm ²
・UV illuminance/light meter uses “UVPF-A1” manufactured by Eye Graphics.

Furthermore, the ratio of Young's modulus E1 to Young's modulus E0 (E1/E0) and the ratio of Young's modulus E2 to Young's modulus E1 (E2/E1) were calculated from the three types of Young's modulus obtained as described above. These results are shown in Table 3.

[Test Example 4] (Evaluation of initial adhesion)
The release sheet was peeled off from the workpiece processing sheets produced in Examples and Comparative Examples, and # A polished surface of a 6-inch silicon wafer (thickness: 350 μm) that had been polished by 2000 μm was attached. Subsequently, dicing was performed using a dicing device (manufactured by DISCO Corporation, product name "DFD-6362") under the following dicing conditions, in which the 6-inch silicon wafer was cut from the side while supplying running water to the cutting section.

<Dicing conditions>
・Dicing device: DISCO DFD-6362
・Blade: NBC-2H 2050 27HECC manufactured by DISCO
・Blade width: 0.025-0.030mm
・Blade tip extension: 0.640 to 0.760mm
・Blade rotation speed: 50000rpm
・Cutting speed: 20mm/sec
・Cut depth: 20μm from the adhesive layer side of the workpiece processing sheet to the base material
・Flowing water supply amount: 1.0L/min
・Running water temperature: Room temperature ・Cut size: 2mm x 2mm

After that, visually observe the workpiece processing sheet to which the chips obtained in the dicing process are attached, count the number of chips that fell off from the workpiece processing sheet during the dicing process, and calculate that number as the number of divisions in the dicing process. The chip scattering rate (unit: %) was determined. Based on this calculation result, initial tackiness was evaluated using the following criteria. The evaluation results are shown in Table 3.
○: Chip scattering rate is less than 10%.
×: Chip scattering rate is 10% or more.

[Test Example 5] (Evaluation of pickup suitability)
Dicing was performed in the same manner as in Test Example 4 using the workpiece processing sheets manufactured in Examples and Comparative Examples, except that the cut size was changed to 10 mm x 10 mm.

After completion of dicing, the workpiece processing sheet with chips mounted thereon was placed in an oven and heated at 150° C. for 1 hour. Subsequently, the adhesive layer of the workpiece processing sheet was irradiated with ultraviolet rays through the base material under the following conditions.
<Ultraviolet irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 230mW/cm ² , light intensity 190mJ/cm ²
・UV illuminance/light meter uses “UVPF-A1” manufactured by Eye Graphics.

One hundred chips were picked up from the workpiece processing sheet after being irradiated with ultraviolet rays, and their pick-up suitability was evaluated based on the following criteria. The results are shown in Table 3.
◎: Out of 100 chips, the number of chips that were successfully picked up was 95 or more.
Good: Out of 100 chips, the number of chips that were successfully picked up was less than 95 and 80 or more.
x: Out of 100 chips, less than 80 chips were successfully picked up.

In addition, the details of the abbreviations etc. described in Tables 1 and 2 are as follows.
[Composition of active energy ray-curable polymer]
2EHA: 2-ethylhexyl acrylate BA: Butyl acrylate ACMO: Acryloylmorpholine (SP value: 10.1, glass transition temperature: 145°C)
MMA: Methyl methacrylate (SP value: 9.5, glass transition temperature: 105°C)
IBXA: Isobornyl acrylate (SP value: 10.2, glass transition temperature: 94°C)
HEA: 2-hydroxyethyl acrylate MOI: methacryloyloxyethyl isocyanate [photopolymerization initiator]
OmniRad 127: 2-Hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by BASF, product name “OmniRad”) 127'', 5% weight loss temperature: 220℃)
Omnirad TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, product name "Omnirad TPO", 5% weight loss temperature: 225°C)

As can be seen from Table 3, the workpiece processing sheets obtained in Examples had excellent initial adhesion and were able to hold the workpieces well on the sheets during processing. In addition, the sheets for workpiece processing obtained in the examples had excellent pick-up suitability, that is, it was suggested that the adhesion to the processed workpiece was favorably reduced during pick-up.

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

Claims (6)

A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material,
The adhesive layer is composed of an active energy ray-curable adhesive,
The adhesive force of the workpiece processing sheet to the silicon wafer is F0,
After heating the laminate formed by bonding the workpiece processing sheet to a silicon wafer at 150° C. for 1 hour, the adhesive layer constituting the laminate is further exposed to ultraviolet rays at an illuminance of 230 mW/cm ² and a light amount . When the adhesive force of the workpiece processing sheet to the silicon wafer after irradiation under the condition of 190 mJ/cm ² is F2,
The adhesive force F0 is 600 mN/25 mm or more and 20000 mN/25 mm or less,
A workpiece processing sheet characterized in that a ratio (F2/F0) of the adhesive force F2 to the adhesive force F0 is 0.66 or less. After heating the workpiece processing sheet at 150°C for 1 hour, the Young's modulus of the adhesive layer at 23°C is E1,
After heating the workpiece processing sheet at 150° C. for 1 hour, the adhesive layer constituting the workpiece processing sheet was further irradiated with ultraviolet rays at an illuminance of 230 mW/cm ² and a light amount of 580 mJ/cm ² . When the Young's modulus at 23° C. of the adhesive layer afterward is E2,
The workpiece processing sheet according to claim 1, wherein a ratio (E2/E1) of the Young's modulus E2 to the Young's modulus E1 is 13 or more. The Young's modulus at 23°C of the adhesive layer in the workpiece processing sheet is E0,
When the Young's modulus of the adhesive layer at 23°C after heating the workpiece processing sheet at 150°C for 1 hour is E1,
The workpiece processing sheet according to claim 1 or 2, wherein a ratio (E1/E0) of the Young's modulus E1 to the Young's modulus E0 is 2.0 or more. A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material,
The adhesive layer is composed of an active energy ray-curable adhesive,
The glass transition temperature of the active energy ray-curable adhesive is -50°C or more and 10°C or less,
The active energy ray-curable adhesive includes an acrylic copolymer containing a monomer having a polar group as a constituent monomer,
The monomer having a polar group is at least one selected from acryloylmorpholine, isobornyl acrylate, vinyl acetate, benzyl acrylate, and glycidyl methacrylate.
A workpiece processing sheet characterized by: 5. The workpiece processing sheet according to claim 4, wherein the acrylic copolymer has a functional group having active energy ray curability introduced into a side chain. The workpiece processing sheet according to any one of claims 1 to 5, which is a dicing sheet.