Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/26—Esters containing oxygen in addition to the carboxy oxygen
  • C08F220/30—Esters containing oxygen in addition to the carboxy oxygen containing aromatic rings in the alcohol moiety
  • C08F220/301—Esters containing oxygen in addition to the carboxy oxygen containing aromatic rings in the alcohol moiety and one oxygen in the alcohol moiety
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
  • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C09J7/385—Acrylic polymers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7402—Wafer tapes, e.g. grinding or dicing support tapes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7412—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support the auxiliary support including means facilitating the separation of a device or wafer from the auxiliary support
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7416—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support used during dicing or grinding
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P95/00—Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors

Definitions

• the present invention relates to a workpiece processing sheet used for processing workpieces such as semiconductor wafers and a method for using the same.
• Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in a large diameter state, cut (diced) into chips, peeled off (picked up), and then moved to the next process, the mounting process.
• the workpieces such as semiconductor wafers are stacked on an adhesive sheet (hereinafter sometimes referred to as the "workpiece processing sheet") that has a base material and an adhesive layer, and are then processed and treated with backgrinding, dicing, cleaning, drying, expanding, picking up, mounting, etc.
• the adhesive layer may be made of an adhesive that is curable with active energy rays.
• the adhesive strength of the adhesive layer to the workpiece can be reduced by irradiating the adhesive layer with active energy rays, which makes it easier to separate (e.g. pick up) the workpiece from the adhesive sheet. Examples of such workpiece processing sheets are disclosed in Patent Documents 1 and 2.
• the adhesive layer is composed of an acrylic adhesive containing a radiation-polymerizable compound with two or more unsaturated bonds.
• the adhesive layer is composed of an acrylic adhesive containing an acrylic polymer with radiation-curable carbon-carbon double bonds in the molecule.
• the present invention was made in consideration of these circumstances, and aims to provide a new work processing sheet that reduces the environmental impact and allows easy control of adhesive strength.
• the present invention provides a workpiece processing sheet including a substrate and an adhesive layer laminated on one side of the substrate, the adhesive layer being made of an emulsion-based adhesive formed from an adhesive composition containing an acrylic polymer, the acrylic polymer being represented by the following formula (1): (In formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.)
• the present invention provides a workpiece processing sheet having a benzophenyl structure represented by the following formula (Invention 1).
• the adhesive layer is formed using an acrylic polymer having the above benzophenyl structure, which allows for a new method of controlling adhesive strength. Furthermore, the adhesive layer is made of an emulsion-based adhesive, which effectively reduces the environmental impact.
• the acrylic polymer contains a monomer having a benzophenyl structure represented by the formula (1) as a monomer unit constituting the polymer (Invention 2).
• the acrylic polymer is represented by the following formula (2):
• R 2 and R 3 each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and n represents an integer of 1 to 15.
• the compound has a structure represented by the following formula (Invention 3).
• the acrylic polymer contains a monomer having the structure shown in formula (2) as a monomer unit constituting the polymer (Invention 4).
• the workpiece processing sheet is used as at least one of a backgrind sheet, a dicing sheet, and a pick-up sheet (Invention 5).
• the present invention provides a method of using the workpiece processing sheet (Invention 1), which includes an attachment step of attaching the surface of the adhesive layer opposite the substrate to a workpiece, a processing step of processing the workpiece on the workpiece processing sheet, and an irradiation step of irradiating the adhesive layer with active energy rays (Invention 6).
• the present invention can provide a new work processing sheet that reduces the environmental impact and allows easy control of adhesive strength.
• the workpiece processing sheet according to the present embodiment includes a substrate and a pressure-sensitive adhesive layer laminated on one side of the substrate.
• the pressure-sensitive adhesive layer is made of an emulsion-based pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing an acrylic polymer.
• the acrylic polymer is represented by the following formula (1): (In formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.) It has a benzophenyl structure represented by the following formula:
• the adhesive layer in this embodiment is made of an emulsion-based adhesive and therefore does not substantially contain organic solvents. Therefore, the work processing sheet according to this embodiment has a reduced environmental impact. Specifically, there are no problems such as the evaporation of organic solvents during production or the migration of residual organic solvents from the adhesive layer to the surroundings when the work processing sheet is used. Note that the adhesive layer in this embodiment does not substantially contain organic solvents means that the content of organic solvents (particularly volatile organic solvents such as methyl ethyl ketone, toluene, and ethyl acetate) in the adhesive layer is 0.3% or less, and particularly 0.1% or less.
• the adhesive layer in this embodiment contains an acrylic polymer having a benzophenyl structure as shown in formula (1) above, which allows for good curing.
• the workpiece processing sheet according to this embodiment can reduce the adhesive strength to the adherend, making it easier to separate the workpiece after processing.
• the hardening of the adhesive layer described above is caused by a crosslinking reaction between acrylic polymers.
• this crosslinking reaction is a hydrogen abstraction reaction of hydrogen atoms present in the acrylic polymer by the ketone group in the benzophenyl structure shown in formula (1) above.
• this reaction proceeds at multiple sites in the acrylic polymer, a higher-order structure is formed in which the acrylic polymer is crosslinked, and as a result, the adhesive layer has a high elastic modulus.
• the following formula (3) shows an example of the hydrogen abstraction reaction.
• the following formula (3) shows a reaction occurring between any benzophenyl structure in the acrylic polymer (derived from 4-benzoylphenyl methacrylate as a constituent monomer) and any structure containing a hydrogen atom in the acrylic polymer (derived from 2-ethylhexyl acrylate as a constituent monomer).
• the ketone group in the benzophenyl structure abstracts a hydrogen atom bonded to a tertiary carbon atom in the other structure, resulting in the formation of a covalent bond between the carbon atom constituting the ketone group and the tertiary carbon atom to which the hydrogen atom was bonded.
• This hydrogen abstraction reaction is not limited to tertiary carbon atoms, but also occurs from hydrogen atoms bonded to primary or secondary carbon atoms.
• This hydrogen abstraction reaction is not limited to tertiary carbon atoms, but also occurs from hydrogen atoms bonded to primary or secondary carbon atoms.
• formula (3) the possibility of abstracting hydrogen atoms other than those surrounded by dashed lines is not excluded.
• the above-mentioned hydrogen abstraction reaction can be caused by irradiation with a specific active energy ray.
• the active energy ray include ultraviolet light and electron beams, but from the viewpoint of making the reaction occur easily and effectively, ultraviolet light is preferred, and in particular ultraviolet light (UV-C) having a wavelength of 200 to 280 nm is preferred, and in particular ultraviolet light having a wavelength of 250 to 260 nm is preferred.
• UV-C ultraviolet light
• the above-mentioned hydrogen abstraction reaction occurs by irradiation with a specific active energy ray, and as a result, the adhesive layer hardens, so that the work processing sheet according to this embodiment can reduce the adhesive force to the adherend at any time.
• the structure that provides the hydrogen atom in the hydrogen abstraction reaction is not particularly limited as long as it is a hydrogen atom present in the acrylic polymer.
• it may be a hydrogen atom bonded to any carbon atom in the acrylic polymer.
• the acrylic polymer is preferably a structure represented by the following formula (2): (In formula (2), R 2 and R 3 each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and n represents an integer of 1 to 15.) It is preferred that the compound has a structure represented by the formula:
• the substrate in this embodiment is not particularly limited as long as it exhibits the desired function when the workpiece processing sheet is used.
• the substrate is preferably a resin film mainly made of a resin material.
• Specific examples thereof include polyolefin films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate; ethylene-vinyl acetate copolymer film; ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)methyl acrylate copolymer film, and other ethylene-(meth)acrylic acid ester copolymer films; polyvinyl chloride films such as polyvinyl chloride copolymer films; (meth)acrylic
• the substrate may be a laminated film in which a plurality of the above-mentioned films are laminated together.
• the materials constituting the layers may be the same or different.
• the workpiece processing sheet according to this embodiment when used as a dicing sheet, it is preferable to use a polyester film (particularly a polyethylene terephthalate film) as the substrate. Also, when the workpiece processing sheet according to this embodiment is used as a back grinding sheet, it is preferable to use a polyurethane film as the substrate.
• (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.
• polymer also includes the concept of "copolymer.”
• the substrate may contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers.
• additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers.
• the amount of these additives contained is not particularly limited, but is preferably within a range in which the substrate exhibits the desired function.
• the surface of the substrate on which the adhesive layer is laminated may be subjected to a surface treatment such as a primer treatment, corona treatment, or plasma treatment to enhance adhesion to the adhesive layer.
• a surface treatment such as a primer treatment, corona treatment, or plasma treatment to enhance adhesion to the adhesive layer.
• the thickness of the substrate can be set appropriately depending on the method in which the workpiece processing sheet is used, but is preferably, for example, 200 ⁇ m or less, and more preferably 150 ⁇ m or less.
• the thickness of the substrate is preferably 10 ⁇ m or more, and more preferably 25 ⁇ m or more.
• the pressure-sensitive adhesive layer in this embodiment is composed of an emulsion-based pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing an acrylic polymer, and the acrylic polymer has a benzophenyl structure represented by the following formula (1).
• R 1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.
• the number of carbon atoms is preferably 1 to 14, and more preferably 1 to 10.
• a typical example of the benzophenyl structure is a case where all R 1 are hydrogen atoms.
• the benzophenyl structure may be present in any form, but from the viewpoint of ease of preparation of the acrylic polymer, it is preferable that the acrylic polymer contains a monomer having the benzophenyl structure represented by the above formula (1) as a monomer unit constituting the polymer.
• Examples of the monomer include 4-benzoylphenyl (meth)acrylate, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, etc., and among these, 4-benzoylphenyl methacrylate is preferred. These may be used alone or in combination of two or more.
• R 4 represents an alkylene group having 1 to 18 carbon atoms, an oxygen atom, or an -NH- group.
• R 4 represents an alkylene group having 1 to 18 carbon atoms, an oxygen atom, or an -NH- group.
• the ratio of the monomer having the benzophenyl structure represented by the above formula (1) to the monomer units constituting the acrylic copolymer is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more. When the ratio is 0.1% by mass or more, the acrylic copolymer is easily crosslinked. In addition, the ratio is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 20% by mass or less. When the ratio is 15% by mass or less, it becomes easier to secure other monomers that contribute to adhesion, etc., and the adhesive layer is more likely to exhibit the desired performance.
• the acrylic copolymer in the present embodiment is represented by the following formula (2):
• R 2 and R 3 each represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and n represents an integer of 1 to 15.
• R2 is the alkyl group
• the number of carbon atoms is preferably 1 to 18, and more preferably 1 to 10.
• n is preferably 1 to 15, and more preferably 1 to 8.
• the structure represented by the above formula (2) may be present in any form, but from the viewpoint of ease of preparation of the acrylic polymer, it is preferable that the acrylic polymer contains a monomer having the structure represented by the above formula (2) as a monomer unit constituting the polymer.
• Examples of monomers having the structure shown in formula (2) above include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc., with 2-ethylhexyl acrylate being preferred. These may be used alone or in combination of two or more.
• the ratio of the monomer having the structure represented by the above formula (2) to the monomer units constituting the acrylic copolymer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• the acrylic copolymer is easily crosslinked.
• the above ratio is preferably 99.9% by mass or less, more preferably 99% by mass or less, and even more preferably 95% by mass or less.
• the above ratio is 99.9% by mass or less, it becomes easier to secure other monomers that contribute to adhesion, etc., and the adhesive layer is more likely to exhibit the desired performance.
• the acrylic copolymer in this embodiment preferably contains, as a monomer unit constituting the polymer, an alkyl (meth)acrylate having an alkyl group with 1 to 20 carbon atoms, which does not fall under the monomer having the structure represented by the above formula (2).
• alkyl (meth)acrylate alkyl (meth)acrylates in which the alkyl group has 1 to 18 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate, are particularly preferred. These may be used alone or in combination of two or more.
• the ratio of the alkyl (meth)acrylate to the monomer units constituting the acrylic copolymer is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• the ratio is also preferably 99.9% by mass or less, more preferably 99% by mass or less, and even more preferably 95% by mass or less.
• the acrylic copolymer in this embodiment preferably contains a functional group-containing monomer as a monomer unit constituting the polymer.
• the 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, a substituted amino group, or an epoxy group in the molecule.
• Hydroxy group-containing monomers include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc., which may be used alone or in combination of two or more.
• Carboxy group-containing monomers include, for example, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.
• amino group-containing monomers or substituted amino group-containing monomers include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used alone or in combination of two or more.
• the ratio of the functional group-containing monomer to the monomer units constituting the acrylic copolymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more.
• the ratio is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.
• the acrylic polymer in this embodiment is obtained by emulsion polymerization. Any conventionally known emulsion polymerization method can be used.
• the acrylic polymer can be obtained by emulsion polymerization of an emulsion containing one or more acrylic monomers, an emulsifier, and a polymerization initiator by radical polymerization.
• the emulsifier is not particularly limited, and non-reactive emulsifiers, reactive emulsifiers, etc. can be used.
• the non-reactive emulsifiers that can be used include, for example, anionic emulsifiers such as alkylaryl sulfonates, alkyl sulfates, alkenyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkenyl ether sulfates, polyoxyethylene alkylaryl ether sulfates, alkyl sulfosuccinates, alkyl sulfosuccinate derivatives, alkyl diaryl ether disulfonates, and alkyl diaryl ether disulfonate derivatives; and nonionic emulsifiers such as polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, polyoxyethylene alkyl phenyl ethers, sorbitan higher fatty acid esters, polyoxyethylene sorbitan higher fatty acid esters, polyoxyethylene higher fatty acid esters, and glycerin higher fatty acid esters
• the reactive emulsifier for example, the "ADEKA REASOAP” series manufactured by Asahi Denka Kogyo Co., Ltd. or the “Aqualon” series manufactured by Daiichi Kogyo Seiyaku Co., Ltd. can be used.
• the use of a reactive emulsifier can further reduce contamination of the wafer.
• the acrylic polymer obtained by the above emulsion polymerization may be used alone as an adhesive composition, or other components may be added to it to form an adhesive composition.
• examples of the components are not limited as long as they do not impair the above-mentioned effects of the work processing sheet according to the embodiment, and examples of the components that can be added include crosslinking agents, active energy ray curable compounds, photopolymerization initiators, silane coupling agents, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, and refractive index adjusters.
• the adhesive composition does not contain low molecular weight components, and in particular, it is preferable that it does not contain low molecular weight components as active energy ray curable compounds.
• low molecular weight components here refer to components with a molecular weight of 1000 or less, for example, and in particular components with a molecular weight of 800 or less.
• the thickness of the adhesive layer in this embodiment is preferably 1 ⁇ m or more, particularly preferably 3 ⁇ m or more, and even more preferably 5 ⁇ m or more.
• the thickness is also preferably 60 ⁇ m or less, particularly preferably 30 ⁇ m or less, and even more preferably 20 ⁇ m or less.
• the adhesive layer is 60 ⁇ m or less thick, it becomes easier to pick up the workpiece.
• a release sheet may be laminated on the side of the adhesive layer opposite the substrate (hereinafter sometimes referred to as the "adhesive side") in order to protect that side until it is attached to the workpiece.
• the release sheet may have any configuration, and may be, for example, a plastic film that has been treated with a release agent or the like.
• plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene.
• the release agent may be silicone-based, fluorine-based, long-chain alkyl, or rubber-based, and among these, silicone-based agents are preferred because they are inexpensive and provide stable performance.
• the thickness of the release sheet there are no particular limitations on the thickness of the release sheet, and it may be, for example, 16 ⁇ m or more and 250 ⁇ m or less.
• an adhesive layer may be laminated on the surface of the adhesive layer opposite to the substrate.
• the workpiece processing sheet according to this embodiment can be used as a dicing/die bonding sheet.
• a workpiece is attached to the surface of the adhesive layer opposite to the adhesive layer, and the adhesive layer is diced together with the workpiece to obtain a chip on which the individualized adhesive layer is laminated.
• the individualized adhesive layer makes it possible for the chip to be easily fixed to the object on which the chip is mounted.
• thermosetting adhesive component As the material constituting the above-mentioned adhesive layer, it is preferable to use one containing a thermoplastic resin and a low molecular weight thermosetting adhesive component, one containing a B-stage (semi-cured) thermosetting adhesive component, etc.
• a protective film forming layer may be laminated on the adhesive surface of the adhesive layer.
• the workpiece processing sheet according to this embodiment can be used as a sheet for forming a protective film and dicing.
• a workpiece is attached to the surface of the protective film forming layer opposite the adhesive layer, and the protective film forming layer is diced together with the workpiece to obtain a chip on which an individualized protective film forming layer is laminated.
• the protective film forming layer is usually laminated on the 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 manufacturing method of the workpiece processing sheet according to this embodiment is not particularly limited, and it is preferably manufactured by laminating an adhesive layer on one side of a substrate.
• the adhesive layer can be laminated on one side of the substrate by a known method. For example, it is preferable to transfer the adhesive layer formed on a release sheet to one side of the substrate.
• a coating liquid containing an adhesive composition constituting the adhesive layer is prepared, and the coating liquid is applied to the release-treated surface of the release sheet (hereinafter sometimes referred to as the "release surface") using a die coater, curtain coater, spray coater, slit coater, knife coater, applicator, etc. to form a coating film, and the coating film is dried to form the adhesive layer.
• the properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain components for forming the adhesive layer as a solute or as a dispersoid.
• the release sheet in this laminate may be peeled off as a process material, or it may be used to protect the adhesive surface of the adhesive layer until the work processing sheet is attached to the adherend.
• the adhesive layer may be formed directly on the substrate.
• the coating liquid for forming the adhesive layer described above is applied to one side of the substrate to form a coating film, and the coating film is dried to form the adhesive layer.
• the workpiece processing sheet according to this embodiment can be used for processing a workpiece such as a semiconductor wafer. 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 expanding sheet, a pick-up sheet, etc. Examples of the workpiece include semiconductor members such as semiconductor wafers and semiconductor packages, and glass members such as glass plates.
• the workpiece processing sheet according to this embodiment can cure the adhesive layer by irradiating it with a predetermined amount of active energy, effectively reducing the adhesive force to the adherend. Therefore, it is preferable that the workpiece processing sheet according to this embodiment is used as at least one of a backgrind sheet, a dicing sheet, and a pick-up sheet.
• One example of a preferred method of using the workpiece processing sheet according to this embodiment includes an attachment step of attaching the surface of the adhesive layer opposite the substrate to the workpiece, a processing step of processing the workpiece on the workpiece processing sheet, and an irradiation step of irradiating the adhesive layer with active energy rays.
• the specific method is not limited as long as the adhesive surface of the workpiece processing sheet according to this embodiment is attached to the workpiece.
• the subsequent processing step is carried out according to the type of processing, and a conventionally known method can be used.
• a dicing device is used to dice the work on the work processing sheet to obtain multiple semiconductor chips.
• the type of dicing here is not particularly limited, and may be, for example, blade dicing, laser dicing, stealth dicing, etc.
• the irradiation of active energy rays in the irradiation step can be carried out by a conventionally known method.
• the type of active energy rays is as described above.
• the workpiece processing sheet according to this embodiment has the adhesive layer described above, the workpiece processing sheet can be used as a dicing/die bonding sheet. Furthermore, when the workpiece processing sheet according to this embodiment has the protective film forming layer described above, the workpiece processing sheet can be used as a protective film forming/dicing sheet.
• other layers may be provided between the substrate and the adhesive layer, or on the surface of the substrate opposite the adhesive layer.
• Example 1 (1) Preparation of Pressure-Sensitive Adhesive Composition 20 parts by mass of 2-ethylhexyl acrylate, 65 parts by mass of butyl acrylate, 4 parts by mass of methyl methacrylate, 10 parts by mass of 4-benzoylphenyl methacrylate, 1 part by mass of acrylic acid, 1 part by mass of polyoxyethylene alkyl ether sulfate as an emulsifier, and 150 parts of distilled water were added to a four-neck flask equipped with a nitrogen gas inlet tube, a thermometer, a reflux condenser, and a stirrer, and the mixture was thoroughly stirred and heated to 70° C.
• step (2) Preparation of dicing sheet
• the adhesive composition coating solution prepared in step (1) was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031”), which was a 38 ⁇ m-thick polyethylene terephthalate film with a silicone-based release agent layer formed on one side thereof, while adjusting the gap with an applicator.
• the coating film thus obtained was dried at 100° C. for 2 minutes to form an adhesive layer with a thickness of 20 ⁇ m, and a laminate of the adhesive layer and the release sheet was obtained.
• the adhesive layer side of the laminate obtained as described above was bonded to the adhesive treated surface of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name "Diafoil", thickness: 100 ⁇ m) that had been treated for easy adhesion as a substrate, to obtain a workpiece processing sheet having a structure of release sheet/adhesive layer (20 ⁇ m)/substrate.
• This workpiece processing sheet was used as a dicing sheet in Test Examples 1 to 3 described below.
• the adhesive composition coating solution prepared in step (1) was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET3811(S)”), which is a 38 ⁇ m-thick polyethylene terephthalate film with a silicone-based release agent layer formed on one side thereof, while adjusting the gap with an applicator.
• the coating film thus obtained was dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 20 ⁇ m, and a laminate of the adhesive layer and the release sheet was obtained.
• the adhesive layer side of the laminate obtained as described above was bonded to one side of the substrate obtained as described above to obtain a workpiece processing sheet having a release sheet/adhesive layer (20 ⁇ m)/substrate structure.
• This workpiece processing sheet was used as a backgrind sheet in Test Example 4 described below.
• Example 2 Workpiece processing sheets (dicing sheet and backgrind sheet) were produced in the same manner as in Example 1, except that the amount of n-butyl acrylate used was changed to 74.9 parts by mass and the amount of 4-benzoylphenyl methacrylate used was changed to 0.1 parts by mass.
• Comparative Example 1 80 parts by mass of 2-ethylhexyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain an acrylic copolymer. Then, 2-methacryloyloxyethyl isocyanate (MOI) was added in an amount equivalent to 80 mol % of the 2-hydroxyethyl acrylate constituting the acrylic copolymer. After that, the mixture was reacted at 60° C. for 48 hours to obtain an acrylic polymer having an active energy ray-curable group introduced into the side chain.
• MOI 2-methacryloyloxyethyl isocyanate
• Comparative Example 2 Workpiece processing sheets (dicing sheet and backgrind sheet) were produced in the same manner as in Example 1, except that the monomer composition in preparing the acrylic polymer was changed to 83 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of methyl methacrylate, 3 parts by mass of methyl acrylate, and 1 part by mass of acrylic acid.
• Test Example 1 Evaluation of Residual Organic Solvents
• the workpiece processing sheet (dicing sheet) prepared in the examples and comparative examples was cut to a size of 10 mm x 50 mm, and then the release sheet was peeled off, and the laminate of the adhesive layer and the base material obtained was used as a measurement sample.
• the measurement sample was sealed in a measurement vial and heated at 120°C for 30 minutes, and the generated gas was introduced into a gas chromatograph mass spectrometer (manufactured by Shimadzu Corporation, product name "GCMS-QP2010") to confirm the presence or absence of peaks corresponding to methyl ethyl ketone, toluene, and ethyl acetate. Then, the presence or absence of residual organic solvents was evaluated based on the following criteria. The results are shown in Table 1. A: No peaks were observed. ⁇ : At least one peak was observed.
• the substrate side surface of the workpiece processing sheet was irradiated with ultraviolet (UV) rays (illuminance: 230 mW/cm 2 , light quantity: 190 mJ/cm 2 ) using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m/12") to harden the adhesive layer.
• UV ultraviolet
• dicing was performed using a dicing device (manufactured by Disco Corporation, product name "DFD-6362”) under the following dicing conditions.
• the above back grinding was carried out twice independently, and the thickness of the semiconductor silicon wafer was measured after each of the two grindings.
• the back grinding properties were evaluated based on the following criteria. The results are shown in Table 1.
• ⁇ The specified thickness (350 ⁇ m) was achieved both times.
• x The specified thickness (350 ⁇ m) was not achieved at least once.
• the workpiece processing sheet of the present invention can be suitably used for processing workpieces such as semiconductor wafers.

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• 2023
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