Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L53/02—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers of vinyl-aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • 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
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/22—Plastics; Metallised plastics
• • 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]
• • 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
  • H10P95/00—Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass

Definitions

• the present invention relates to polyester films for use in semiconductor manufacturing processes and methods for using the same.
• Semiconductor devices are typically manufactured by forming electronic circuits on the surface of a semiconductor wafer such as a silicon wafer, then dicing the semiconductor wafer into individual semiconductor chips, and packaging the individual semiconductor chips.
• Blade dicing is commonly used for the dicing process, but stealth dicing, which uses laser light for dicing, is also becoming more common.
• the backside of the semiconductor wafer is typically ground to adjust the thickness.
• Patent Document 2 discloses a surface protection film having an anchor coat layer containing a copolymer polyurethane resin on one side of a core film.
• Patent Documents 3 and 4 disclose, as substrate films for backgrinding tapes, three-layer films in which the front and back layers and the middle layer are each made of soft polyester and polyester-based elastomer, and three-layer films in which the front and back layers are made of polyester-based resin and the middle layer is made of soft polyester-based resin.
• Patent Document 5 discloses a carrier tape in which the middle layer is made of copolymer polyester and both surface layers are made of polybutylene terephthalate or polybutylene naphthalate.
• JP 2023-94525 A Japanese Patent Application Laid-Open No. 2012-216619 JP 2010-225675 A Japanese Patent Application Laid-Open No. 2021-146675 Japanese Patent Application Publication No. 04-257444
• polyester resin is widely used in large quantities and can be recycled not only physically but also chemically through a depolymerization reaction. Therefore, it has attracted attention as a resin with excellent recyclability, and the reuse of PET bottles, which are consumed in large quantities, is progressing. Furthermore, in recent years, from the perspective of environmental protection, there has been a growing demand to reuse not only PET bottles but also polyesters used in a variety of applications. For example, there is also a growing demand to reuse the base material of process films such as dicing tape used in semiconductor manufacturing processes.
• polyester films have excellent recyclability, they are difficult to practically use in semiconductor manufacturing processes because they cannot sufficiently relieve stress by themselves or cannot have sufficiently high mechanical strength.
• the polyester films disclosed in Patent Documents 3 to 5 have difficulty in obtaining excellent stress relaxation properties while increasing mechanical strength.
• a layer of a different resin such as a polyethylene layer is laminated on a substrate made of PET or the like as in Patent Documents 1 and 2
• the stress relaxation property is excellent, there is a problem that recycling is difficult.
• it is difficult to use it as a recycled raw material unless the anchor coat layer containing the copolymer polyurethane resin applied to the core film is removed by washing with a detergent or the like.
• the present invention provides the following [1] to [22].
• the polyester film for semiconductor manufacturing processes has a Young's modulus of 2 GPa or more.
• the copolymer polyester (a) comprises a copolymer polyester (a1) which is a copolymer of a dicarboxylic acid component containing terephthalic acid and a dicarboxylic acid component (X2) having 4 to 10 carbon atoms and a diol component containing an aliphatic diol (Y).
• the intermediate layer (B) contains a copolymer polyester composed of a copolymer of a dicarboxylic acid component and a diol component,
• the proportion (mol %) of the dicarboxylic acid component having 4 to 10 carbon atoms other than terephthalic acid in the dicarboxylic acid components in all the polyesters contained in the intermediate layer (B) is (B1)
• the proportion (mol %) of the diol component other than ethylene glycol in the diol components in all the polyesters contained in the intermediate layer (B) is (B4)
• the surface layer (A) contains a copolymer polyester composed of a copolymer of a dicarboxylic acid component and a diol component
• the intermediate layer (B) contains a copolymer polyester formed from a copolymer of a dicarboxylic acid component and a diol component
• the proportion (mol %) of the dicarboxylic acid component having 4 to 10 carbon atoms other than terephthalic acid in all the dicarboxylic acid components contained in the surface layer (A) is defined as (A1)
• the ratio (mol %) of the diol components other than ethylene glycol to the diol components in all the polyesters contained in the surface layer (A) is (A4)
• the proportion (mol %) of the dicarboxylic acid component having 4 to 10 carbon atoms other than terephthalic acid in the dicarboxylic acid components in all the polyesters contained in the intermediate layer (B) is (B1), and the proportion (mol %) of the diol component other
• the polyester film for semiconductor manufacturing process according to any one of [1] to [15] above which is a coextrusion stretched film.
• the polyester film for semiconductor manufacturing processes according to any one of [1] to [16] above which is for use as a backgrinding tape or a dicing tape.
• a laminated film comprising the polyester film for semiconductor manufacturing process according to any one of [1] to [17] above, and at least one resin layer provided on the one surface or the other surface of the polyester film for semiconductor manufacturing process.
• the laminated film according to the above [18], wherein the resin layer includes an antistatic layer, and the surface on which the antistatic layer is provided has a surface resistivity of 1 ⁇ 10 12 ⁇ / ⁇ or less.
• the polyester film for semiconductor manufacturing process of the present invention (hereinafter, sometimes simply referred to as “the film”) has a hardness of 450 MPa or less as measured on one surface of the film using a nanoindenter at 23 ⁇ 5°C (hereinafter, sometimes simply referred to as "hardness").
• the present film is a polyester film having a thermoplastic polyester layer containing a thermoplastic polyester, and the thermoplastic polyester layer is the surface layer (A) of the present film.
• the surface layer (A) is a layer that constitutes the surface of the present film.
• the present film has a hardness of one surface of 450 MPa or less, and therefore the hardness of the surface layer (A) measured at 23 ⁇ 5°C using a nanoindenter is 450 MPa or less.
• This film is highly recyclable due to the use of polyester film. Furthermore, the hardness of one surface (i.e., the hardness of the surface layer (A)) is 450 MPa or less, resulting in good stress relaxation properties. Therefore, by attaching a protective sheet based on this film to a semiconductor wafer, it is possible to adequately protect the wafer or chip during the semiconductor manufacturing process. More specifically, it is possible to adequately relieve stresses such as shear forces acting on the wafer or chip during wafer grinding, effectively preventing cracking of the wafer or chip.
• the above hardness is preferably 350 MPa or less, more preferably 310 MPa or less, even more preferably 250 MPa or less, even more preferably 200 PMa or less, and even more preferably 180 MPa or less.
• the hardness of the present film is not particularly limited, but is preferably 40 MPa or more, more preferably 60 MPa or more, even more preferably 80 MPa or more, and even more preferably 100 PMa or more.
• the mechanical strength of the film is increased, giving the film stiffness and enabling it to properly hold a wafer when attached to the wafer as a protective sheet.
• the hardness of at least one surface of this film is within the above range, but it is also preferable for the hardness of both surfaces to be within the above range.
• a wafer with a protective sheet attached may be placed on a suction table with the protective sheet in between during grinding, in which case the surface opposite the surface adhered to the wafer will be in contact with the suction table. Therefore, when the hardness of both surfaces is below the specified value as described above, stress is alleviated on one surface, while unevenness caused by foreign matter on the suction table is filled in on the other surface, allowing for close contact with the suction table. As a result, cracks in wafers and chips caused by foreign matter can be further reduced.
• the hardness of the present film can be adjusted by the type of resin used in the present film, the composition and amount of each resin, etc. It can also be adjusted by various manufacturing conditions in the manufacturing method of the present film, such as the heat setting temperature. More specifically, if the heat setting temperature is increased, the crystals contained in the film are more likely to melt during heat setting, which tends to reduce the hardness.
• the surface hardness of the polyester film (hardness of the surface layer (A)) can be measured by pressing the probe of a nanoindenter into the surface of the polyester film.
• the Young's modulus of the present film is preferably 2 GPa or more.
• a Young's modulus of 2 GPa or more provides good mechanical strength, allowing the present film to properly hold wafers and chips, and making it easier to prevent damage to wafers and chips during the semiconductor manufacturing process. This makes the present film suitable for use in semiconductor manufacturing.
• the Young's modulus is more preferably 3 GPa or more, and even more preferably 3.5 GPa or more. From the viewpoint of ensuring the flexibility of the present film and reducing hardness, the Young's modulus is preferably 20 GPa or less, more preferably 15 GPa or less, even more preferably 10 GPa or less, and even more preferably 5 GPa or less.
• the Young's modulus may be measured in the longitudinal direction (MD) and transverse direction (TD) of the film and then averaged.
• one or both surfaces of the polyester film may have a resin layer such as an easy-adhesion layer or an antistatic layer, but if the thickness of the resin layer is about several hundred nm or less (for example, 500 nm or less), the influence of the resin layer can be substantially ignored in measuring the Young's modulus. Therefore, the Young's modulus of the polyester film having such a resin layer on its surface can be measured and used as the Young's modulus of the polyester film. The same applies to the various physical properties of the polyester film described below.
• the Young's modulus can be appropriately controlled by the layer structure of the film, the thickness of each layer, the type and amount of resin used in each layer, the production method, and the like.
• the present film has a thermoplastic polyester contained in the thermoplastic polyester layer constituting the surface layer (A).
• the thermoplastic polyester layer may contain at least a thermoplastic polyester.
• the present film contains a copolymer polyester formed from a copolymer of a dicarboxylic acid component and a diol component.
• the copolymer polyester By including the copolymer polyester, the present film has low hardness and is likely to have good stress relaxation properties.
• Specific examples of the copolymer polyester include copolymer polyester (a) which is a copolymer of a dicarboxylic acid component containing terephthalic acid (X1) and a diol component containing an aliphatic diol (Y).
• the copolymer polyester (a) is other than the polyarylate (c) described below.
• the copolymer polyester (a) contained in the present film preferably has thermoplastic properties.
• the copolymer polyester (a) is preferably a copolymer polyester (a1) which is a copolymer of a dicarboxylic acid component containing terephthalic acid (X1) and a dicarboxylic acid component (X2) having 4 to 10 carbon atoms, and a diol component containing an aliphatic diol (Y).
• the dicarboxylic acid component (X2) having 4 to 10 carbon atoms means a dicarboxylic acid component having 4 to 10 carbon atoms excluding terephthalic acid (X1).
• the copolymer polyester (a1) is a polycondensate of a dicarboxylic acid component containing terephthalic acid (X1) and a dicarboxylic acid component (X2) having 4 to 10 carbon atoms, and a diol component containing an aliphatic diol (Y).
• a dicarboxylic acid component (X2) having 4 to 10 carbon atoms other than terephthalic acid as the dicarboxylic acid, it becomes easier to reduce the hardness and improve the stress relaxation properties.
• dicarboxylic acid component (X2) having 4 to 10 carbon atoms examples include aromatic dicarboxylic acids, alicyclic dicarboxylic acids, aliphatic dicarboxylic acids, and polyfunctional acids. Among these, aromatic dicarboxylic acids and aliphatic dicarboxylic acids are preferred, and aliphatic dicarboxylic acids are particularly preferred from the viewpoint of ease of reducing hardness.
• the aliphatic dicarboxylic acid may be used alone as the dicarboxylic acid component (X2) having 4 to 10 carbon atoms, or two or more dicarboxylic acid components having 4 to 10 carbon atoms may be used in combination.
• Examples of the aliphatic dicarboxylic acid having 4 to 10 carbon atoms include saturated aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Among these, from the viewpoint of ease of reaction during polymerization, adipic acid and sebacic acid are more preferred, and adipic acid is even more preferred. Furthermore, as the aromatic dicarboxylic acid, isophthalic acid is preferred.
• the proportion of the dicarboxylic acid component (X2) having 4 to 10 carbon atoms in the dicarboxylic acid components constituting the copolymerized polyester (a1) is not particularly limited, but is, for example, 5 mol % or more and 35 mol % or less, preferably 7 mol % or more and 30 mol % or less, more preferably 9 mol % or more and 25 mol % or less, and even more preferably 11 mol % or more and 20 mol % or less.
• the proportion of terephthalic acid (X1) in the dicarboxylic acid components constituting the copolymer polyester (a1) is, for example, 65 mol % or more and 95 mol % or less, preferably 75 mol % or more and 92 mol % or less, and more preferably 80 mol % or more and 90 mol % or less.
• the dicarboxylic acid component may consist of terephthalic acid (X1) and a dicarboxylic acid component (X2) having 4 to 10 carbon atoms, or may contain a dicarboxylic acid component (other dicarboxylic acid component (X3)) other than terephthalic acid (X1) and the dicarboxylic acid component (X2) having 4 to 10 carbon atoms as a copolymerization component, provided that the gist of the present invention is not impaired.
• dicarboxylic acid components include dodecanedioic acid, eicosanoic acid, dimer acid, and derivatives thereof.
• the proportion of the other dicarboxylic acid component (X3) in the dicarboxylic acid components constituting the copolymer polyester (a1) is, for example, 10 mol % or less, preferably 5 mol % or less, more preferably 3 mol % or less, and most preferably 0 mol %.
• aliphatic diol (Y) examples include chain aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,4-hexanediol, 1,6-hexanediol, diethylene glycol, trimethylene glycol, pentamethylene glycol, octamethylene glycol, decamethylene glycol, neopentyl glycol, and 2-ethyl-2-butyl-1,3-propanediol; alicyclic diols such as 1,2-cyclohexanediol, 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethanol, and 2,5-norbornanedimethylol; and aliphatic dimer diols.
• chain aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,4-hexanediol, 1,6-hexane
• the aliphatic diol is preferably an aliphatic diol having 2 to 8 carbon atoms, more preferably an aliphatic diol having 4 to 8 carbon atoms, and even more preferably an aliphatic diol having 4 to 6 carbon atoms. Furthermore, the aliphatic diol is preferably a chain aliphatic diol. More specifically, the aliphatic diol is preferably at least one selected from ethylene glycol, diethylene glycol, 1,4-butanediol, 1,4-hexanediol, and 1,6-hexanediol.
• the copolymer polyester (a1) may contain a diol component other than the aliphatic diol (Y).
• diol components other than the aliphatic diol (Y) include aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'- ⁇ -hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, and bis(4- ⁇ -hydroxyethoxyphenyl)sulfonic acid; ethylene oxide or propylene oxide adducts of 2,2-bis(4'-hydroxyphenyl)propane; and aromatic dimer diols.
• the proportion of the aliphatic diol (Y) in the diol component constituting the copolymer polyester (a1) is, for example, 50 mol% or more and 100 mol% or less, preferably 70 mol% or more and 100 mol% or less, and more preferably 90 mol% or more and 100 mol% or less. It is preferable that the copolymer polyester (a1) has thermoplastic properties.
• the copolymer polyester (a1) is preferably a copolymer polyester containing an aliphatic diol other than ethylene glycol (Y1) as the aliphatic diol component (Y) (hereinafter also referred to as copolymer polyester (a1-1)), and among these, a copolymer polyester (a1-1) containing an aliphatic diol (Y2) having 4 to 8 carbon atoms as the aliphatic diol component (Y) is more preferred.
• the copolymer polyester (a1-1) more preferably contains at least 1,4-butanediol as the aliphatic diol component (Y).
• the copolymer polyester (a1-1) two or more types of aliphatic diols (Y) are preferably used.
• the aliphatic diol (Y) preferably contains two or more aliphatic diols having 4 to 8 carbon atoms, and more preferably contains both 1,4-butanediol and 1,6-hexanediol.
• the mass ratio thereof (1,4-butanediol/1,6-hexanediol) is preferably 10/90 to 70/30, more preferably 20/80 to 60/40, and even more preferably 30/70 to 50/50.
• the proportion of the aliphatic diol having 4 to 8 carbon atoms in the diol component constituting the copolymer polyester (a1-1) is, for example, 50 mol% or more and 100 mol% or less, preferably 70 mol% or more and 100 mol% or less, and more preferably 90 mol% or more and 100 mol% or less.
• copolymer polyester (a1-1) it is preferable to use an aliphatic dicarboxylic acid having 4 to 10 carbon atoms as the dicarboxylic acid component (X2) having 4 to 10 carbon atoms, and adipic acid is particularly preferable.
• the copolymer polyester (a1-1) preferably has thermoplastic properties.
• Copolymer polyester (a1-2) As another embodiment of the copolymer polyester (a1), a copolymer polyester containing ethylene glycol as the aliphatic diol component (Y) (hereinafter also referred to as copolymer polyester (a1-2)) is preferred.
• the diol component in the copolymer polyester (a1-2) may be ethylene glycol alone, or may contain a diol component other than ethylene glycol.
• Specific examples of the diol component other than ethylene glycol are as described for the copolymer polyester (a1), and preferably an aliphatic diol (Y2) having 4 to 8 carbon atoms.
• the proportion of ethylene glycol in the diol component constituting the copolymer polyester (a1-2) is, for example, 50 mol % to 100 mol %, preferably 70 mol % to 100 mol %, and more preferably 90 mol % to 100 mol %.
• an aromatic dicarboxylic acid as the dicarboxylic acid component (X2) having 4 to 10 carbon atoms, and among these, isophthalic acid is preferred.
• the copolymer polyester (a1-2) preferably has thermoplastic properties.
• copolymer polyester (a2) examples include copolymer polyester (a2), which is a copolymer of a diol component containing terephthalic acid (X1) and two or more aliphatic diols (Y).
• aliphatic diol (Y) Specific examples of the aliphatic diol (Y) are as described above, but among them, an aliphatic diol having 4 to 8 carbon atoms is preferred. It is also preferred to use an aliphatic diol having 4 to 8 carbon atoms in combination with ethylene glycol.
• the dicarboxylic acid component may consist of terephthalic acid (X1) alone, but may also contain other dicarboxylic acids. It is preferable that the copolymer polyester (a2) has thermoplastic properties.
• the present film may contain a homopolyester (b).
• a homopolyester (b) By containing the homopolyester (b), the present film is likely to have good mechanical strength (Young's modulus, etc.), heat resistance, etc.
• the homopolyester (b) include a polymer of terephthalic acid (X1) and any one of the diol components of the aliphatic diol (Y).
• X1 terephthalic acid
• Y terephthalic acid
• Specific examples of the aliphatic diol (Y) are as described above, but among the above, the aliphatic diol (Y) is preferably any of the aliphatic diols having 2 to 8 carbon atoms.
• the aliphatic diol is preferably any of ethylene glycol, diethylene glycol, 1,4-butanediol, 1,4-hexanediol, 1,6-hexanediol, or 1,4-cyclohexanedimethanol, with ethylene glycol or 1,4-cyclohexanedimethanol being more preferred.
• polyethylene terephthalate in which the dicarboxylic acid component is terephthalic acid (X1) and the diol component is ethylene glycol (Y1) is preferred.
• polyethylene terephthalate referred to as a homopolyester may contain diethylene glycol, which is an unavoidable diol component.
• the proportion of diethylene glycol in the diol component may be, for example, 5 mol% or less, or may be 3 mol% or less.
• polyester (b) examples include polycyclohexylene dimethylene terephthalate, which is a polymer of terephthalic acid (X1) and 1,4-cyclohexanedimethanol.
• the homopolyester (b) preferably has thermoplastic properties.
• the present film may contain polyarylate (c) in addition to the copolymer polyester (a) or the copolymer polyester (a) and the homopolyester (b).
• the use of the copolymer polyester (a) in the present film tends to lower the glass transition temperature (Tg), but the addition of polyarylate (c) results in a film with a high glass transition temperature. This reduces breakage during stretching and improves handling during processing. Furthermore, it is easier to obtain a film with excellent heat resistance.
• the dicarboxylic acid component (c-1) constituting the polyarylate (c) is not particularly limited as long as it is a divalent aromatic carboxylic acid, but among these, a mixture of a terephthalic acid component and an isophthalic acid component is preferred.
• the polyarylate (c) has excellent heat resistance and melt moldability.
• the dihydric phenol component (c-2) constituting the polyarylate (c) is not particularly limited as long as it is a dihydric phenol, but it preferably contains either a bisphenol A component or a bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane) component, or both bisphenol A and bisphenol TMC.
• a bisphenol A component results in a polyarylate having excellent melt moldability (fluidity)
• the inclusion of a bisphenol TMC component results in a polyarylate (c) having an improved glass transition temperature and excellent heat resistance.
• both the bisphenol A component and the bisphenol TMC component are used.
• the polyarylate (c) may be copolymerized with a bisphenol component other than bisphenol A (2,2-bis(4-hydroxyphenyl)propane) and bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane) as the dihydric phenol component (c-2).
• bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane), bisphenol AF (2,2-bis(4-hydroxyphenyl)hexafluoropropane), bisphenol B (2,2-bis(4-hydroxyphenyl)butane), bisphenol BP (bis(4-hydroxyphenyl)diphenylmethane), bisphenol C (2,2-bis(3-methyl-4-hydroxyphenyl)propane), bisphenol E (1,1-bis(4-hydroxyphenyl)ethane), bisphenol F (bis(4-hydroxyphenyl)methane), bis Examples include phenol G (2,2-bis(4-hydroxy-3-isopropylphenyl)propane), bisphenol M (1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene), bisphenol S (bis(4-hydroxyphenyl)sulfone), bisphenol P (1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzen
• polyarylate (c) it is preferable to select a mixture of a terephthalic acid component and an isophthalic acid component as the dicarboxylic acid component (c-1), and either a bisphenol A component, a bisphenol TMC component, or a mixture of bisphenol A and bisphenol TMC as the dihydric phenol component (c-2).
• the polyarylate (c) may be mixed with polycarbonate to improve melt moldability. Since the polyarylate (c) and polycarbonate are compatible with each other, mixing the polyarylate (c) with polycarbonate can lower the glass transition temperature of the polyarylate (c) while maintaining transparency and mechanical properties, thereby improving melt moldability.
• the mixing ratio (mass %) of polyarylate (c)/polycarbonate is preferably from 99/1 to 50/50, more preferably from 98/2 to 60/40, still more preferably from 97/3 to 70/30, and particularly preferably from 96/5 to 80/20.
• the melt moldability of polyarylate (c) can be improved while maintaining the heat resistance of the polyarylate (c). It is preferable to mix the polyarylate (c) and the polycarbonate by using a premix of these two components as a raw material, but this is not limited to this method.
• the above-mentioned configuration may also be achieved by selecting the polycarbonate as another resin and using it as an independent raw material.
• the polycarbonate mixed with the polyarylate (c) is not included in the content of the polyarylate (c).
• the thickness of the present film is not particularly limited, but is, for example, in the range of 20 ⁇ m to 250 ⁇ m, preferably 30 ⁇ m to 220 ⁇ m, more preferably 35 ⁇ m to 200 ⁇ m, even more preferably 40 ⁇ m to 180 ⁇ m, and even more preferably 45 ⁇ m to 120 ⁇ m.
• the present film may be a stretched film or a non-stretched film, but is preferably a stretched film.
• the stretched film may be a uniaxially stretched film, but is preferably a biaxially stretched film. By forming the present film into a stretched film, mechanical strength such as Young's modulus can be easily improved.
• the stretched film is preferably a coextrusion stretched film formed by coextrusion.
• the present film may be a monolayer film having a monolayer structure or a multilayer film having a multilayer structure, but is preferably a multilayer film.
• a multilayer film it is preferable to have an intermediate layer (B) and a surface layer (A) provided on at least one side of the intermediate layer (B), and it is preferable to have the surface layer (A) provided on both sides of the intermediate layer (B). Therefore, the present film may have a two-layer structure of intermediate layer (B)/surface layer (A), but is preferably a three-layer structure of surface layer (A)/intermediate layer (B)/surface layer (A).
• the surface layer is on the surface of the film, it is not limited to a two-layer or three-layer structure, and may have a layer structure of four or more layers, including two or more intermediate layers (B).
• this film can reduce the surface hardness while the intermediate layer (B) can impart mechanical strength such as a high Young's modulus. Furthermore, by having surface layers (A) on both sides, this film can contain layers with low hardness on both sides. Therefore, as mentioned above, stress can be alleviated on one side while unevenness caused by foreign matter, etc. can be filled in on the other side, further preventing cracks in wafers and chips.
• At least one surface layer (A), preferably both surface layers (A), contains a thermoplastic polyester. It is also preferable that the intermediate layer (B) in the multilayer film also contains a thermoplastic polyester. By including a thermoplastic polyester in the intermediate layer (B), the recyclability of the film can be improved while also improving mechanical strength such as Young's modulus.
• each surface layer (A) in the multilayer film is preferably 1% to 25% of the total thickness of the film, more preferably 3% to 20%, and even more preferably 5% to 15%.
• the thickness of each surface layer (A) in the multilayer film is, for example, 2 ⁇ m or more and 40 ⁇ m or less, preferably 3 ⁇ m or more and 30 ⁇ m or less, more preferably 3.5 ⁇ m or more and 20 ⁇ m or less, and even more preferably 4 ⁇ m or more and 15 ⁇ m or less.
• the thickness of the intermediate layer (B) in the multilayer film is preferably 60% to 98% of the total thickness of the film, more preferably 70% to 96%, and even more preferably 75% to 92%.
• the surface layer (A) can adequately perform stress relaxation, while the intermediate layer (B) can impart appropriate mechanical strength to the entire film.
• the thickness of the intermediate layer (B) in the multilayer film is, for example, 10 ⁇ m or more and 200 ⁇ m or less, preferably 20 ⁇ m or more and 150 ⁇ m or less, more preferably 25 ⁇ m or more and 125 ⁇ m or less, even more preferably 30 ⁇ m or more and 100 ⁇ m or less, and still more preferably 40 ⁇ m or more and 80 ⁇ m or less.
• the monolayer film itself constitutes the surface layer (A).
• the film in the case of a monolayer film, can be said to be a film consisting of surface layers (A) that constitute both surfaces of the film.
• the present film preferably contains a copolymer polyester on one surface of the film, and preferably on both surfaces. Therefore, in a multilayer film, the surface layer (A) preferably contains a copolymer polyester, and when surface layers (A) are provided on both surfaces of the film, both surface layers (A) preferably contain a copolymer polyester.
• the copolymer polyester contained on the surface is preferably the copolymer polyester (a) described above.
• the present film i.e., the surface layer (A)
• the present film preferably contains a copolymer polyester, more preferably the above-mentioned copolymer polyester (a).
• the content of copolymerized polyester (a) on each surface of the present film is not particularly limited as long as it is adjusted so that the proportions of each component (A1) and (A4) described below fall within predetermined ranges.
• it is 10% by mass or more and 97% by mass or less, preferably 10% by mass or more and 90% by mass or less, more preferably 15% by mass or more and 85% by mass or less, even more preferably 20% by mass or more and 70% by mass or less, and even more preferably 25% by mass or more and 60% by mass or less.
• the present film preferably contains a homopolyester (b) in addition to the copolymer polyester (a) on one surface of the film, and preferably contains a homopolyester (b) in addition to the copolymer polyester (a) on both surfaces. Therefore, in a multilayer film, the surface layer (A) preferably contains the copolymer polyester (a) and the homopolyester (b), and when the surface layer (A) is provided on both surfaces of the film, it is preferable that both surface layers (A) contain the copolymer polyester (a) and the homopolyester (b).
• the specific value of the ratio (B3) is not particularly limited, but it may be 0 mol% or more, but from the viewpoint of making the composition closer to that of the surface layer (A) and facilitating stretching, etc., it is better to have a certain value or more, and it may be 0.5 mol% or more, or may be 1 mol% or more. Furthermore, the ratio (B3) may be, for example, 8 mol% or less, but is preferably 4 mol% or less, and more preferably 3 mol% or less.
• soft styrene resins include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), silicone-acrylic composite rubber-acrylonitrile-styrene copolymers (SAS), methyl methacrylate-maleic anhydride-styrene copolymers (SMM), acrylonitrile-styrene copolymers (AS), acrylonitrile-butadiene-styrene copolymers (ABS), acrylonitrile-styrene-acrylic rubber copolymers (ASA), acrylonitrile-ethylene propylene rubber-styrene copolymers (AES), etc.
• SBS styrene-butadiene-styrene block copolymers
• SIS styrene-isoprene-styrene block cop
• Specific commercial products include the "Kraton D” series manufactured by Kraton Polymers, the "AR-100” series manufactured by Aron Kasei Corporation, the “Dialac” series manufactured by UMG ABS, and the “Delpet” series manufactured by Asahi Kasei Chemicals Corporation.
• the soft styrene-based resin the "Dynaron” series manufactured by JSR Corporation, the “Tuftec” series manufactured by Asahi Kasei Chemicals Corporation, the “Hybler” series manufactured by Kuraray Co., Ltd., and the like can also be used as the styrene-based elastomer described below.
• a polar functional group can also be added to the flexible styrene-based resin.
• the polar functional group include an acid anhydride group, a carboxylic acid group, a carboxylic acid ester group, a carboxylic acid chloride group, a carboxylic acid amide group, a carboxylic acid salt group, a sulfonic acid group, a sulfonic acid ester group, a sulfonic acid chloride group, a sulfonic acid amide group, a sulfonic acid salt group, an epoxy group, an amino group, an imide group, and an oxazoline group.
• modified SEBS and SEPS are preferably used as the flexible styrene-based resin to which a polar functional group is imparted.
• modified SEBS and SEPS include maleic anhydride-modified SEBS, maleic anhydride-modified SEPS, epoxy-modified SEBS, and epoxy-modified SEPS.
• Specific commercial products include the "Tuftec M” series manufactured by Asahi Kasei Chemicals Corporation, the “Dynaron” series manufactured by JSR Corporation, and the "Epofriend” series manufactured by Daicel Chemical Industries, Ltd.
• the polyester elastomer is a thermoplastic polyester that has rubber properties at room temperature, preferably a thermoplastic elastomer primarily composed of a polyester block copolymer, and is preferably a block copolymer having a high-melting-point, highly crystalline aromatic polyester as the hard segment and an amorphous polyester or amorphous polyether as the soft segment.
• the soft segment content of the polyester elastomer is at least 20 to 95 mol% of all segments, and in the case of a block copolymer of polybutylene terephthalate and polytetramethylene glycol (PTMG-PBT copolymer), it is 50 to 95 mol%.
• the preferred soft segment content is 50 to 90 mol%, particularly 60 to 85 mol%.
• polyester ether block copolymers, especially PTMG-PBT copolymers are preferred due to their minimal loss of transmittance.
• polymer components that form the core include butadiene-based rubbers such as polybutadiene and styrene-butadiene copolymers, isoprene-based rubbers, acrylic rubbers such as polybutyl acrylate, poly(2-ethylhexyl acrylate), and butyl acrylate-2-ethylhexyl acrylate copolymers, silicone-based rubbers such as polyorganosiloxane rubber, butadiene-acrylic composite rubbers, and silicone-acrylic composite rubbers such as IPN (Interpenetrating Polymer Network) composite rubbers made of polyorganosiloxane rubber and polyalkyl acrylate rubber, ethylene- ⁇ -olefin-based rubbers such as ethylene-propylene copolymers, ethylene-butene copolymers, and ethylene-octene copolymers, ethylene-acrylic rubbers, and fluororubbers.
• butadiene-based rubbers such as
• the monomer component constituting the shell and capable of graft copolymerization with the core polymer component include aromatic vinyl compounds; vinyl cyanide compounds; (meth)acrylic compounds such as (meth)acrylic acid ester compounds, (meth)acrylic acid compounds, and epoxy group-containing (meth)acrylic acid ester compounds such as glycidyl (meth)acrylate; maleimide compounds such as maleimide, N-methylmaleimide, and N-phenylmaleimide; ⁇ , ⁇ -unsaturated carboxylic acid compounds such as maleic acid, phthalic acid, and itaconic acid, and anhydrides thereof (e.g., maleic anhydride).
• aromatic vinyl compounds vinyl cyanide compounds
• (meth)acrylic compounds such as (meth)acrylic acid ester compounds, (meth)acrylic acid compounds, and epoxy group-containing (meth)acrylic acid ester compounds such as glycidyl (meth)acrylate
• maleimide compounds such as maleimide, N
• aromatic vinyl compounds, vinyl cyanide compounds, and (meth)acrylic compounds are preferred from the viewpoints of mechanical properties and surface appearance, and aromatic vinyl compounds and (meth)acrylic compounds are more preferred, with (meth)acrylic acid ester compounds being more preferred.
• aromatic vinyl compound examples include styrene, ⁇ -methylstyrene, 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, and halogenated styrenes, and among these, styrene and ⁇ -methylstyrene are more preferred.
• the (meth)acrylic acid ester compound examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and octyl (meth)acrylate.
• methyl (meth)acrylate and ethyl (meth)acrylate which are relatively easily available, are preferred, and methyl (meth)acrylate is more preferred.
• “(meth)acrylic” collectively refers to "acrylic” and "methacrylic.”
• a core-shell graft copolymer is particularly preferred, which comprises a core made of at least one polymer component selected from butadiene rubber, acrylic rubber, silicone rubber, and silicone-acrylic composite rubber, and a shell formed by graft copolymerizing a (meth)acrylic compound such as a (meth)acrylic acid ester or an aromatic vinyl compound around the core.
• the content of the polymer component in the core of the core-shell graft copolymer is preferably 40% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.
• core-shell elastomers include methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), methyl methacrylate-butadiene copolymer (MB), methyl methacrylate-acrylic rubber copolymer (MA), methyl methacrylate-acrylic rubber-styrene copolymer (MAS), methyl methacrylate-acrylic-butadiene rubber copolymer, methyl methacrylate-acrylic-butadiene rubber-styrene copolymer, and methyl methacrylate-(acrylic-silicone composite rubber) copolymer.
• MVS methacrylate-butadiene-styrene copolymer
• MABS methyl methacrylate-acrylonitrile-butadiene-styrene copolymer
• MB methyl methacrylate
• core-shell type graft copolymers include, for example, "Paraloid EXL2602,”"ParaloidEXL2603,””ParaloidEXL2690,””ParaloidEXL2691J,””ParaloidEXL2650J,””ParaloidEXL2655,””ParaloidEXL2311,””ParaloidEXL2313,””ParaloidEXL2315,””ParaloidKM330,””ParaloidKM336P,” and “Paraloid KM336P,” all manufactured by Dow Chemical Japan.
• Examples of such a polymer include “KCZ201” manufactured by Mitsubishi Chemical Corporation, “Metablen C-223A”, “Metablen E-901", “Metablen S-2001”, “Metablen W-450A”, and “Metablen SRK-200” manufactured by Mitsubishi Chemical Corporation, and “Kane Ace M-210", “Kane Ace M-511”, “Kane Ace M-600”, “Kane Ace M-400", “Kane Ace M-580", “Kane Ace M-590", “Kane Ace M-711", “Kane Ace MR-01", and “Kane Ace M-300” manufactured by Kaneka Corporation.
• These impact modifiers such as core-shell type graft copolymers may be used alone or in combination of two or more.
• the content of the impact modifier is preferably 30% by mass or less on each surface of the film (i.e., each surface layer (A)). By setting it to 30% by mass or less, it is possible to achieve effects commensurate with the content and also to prevent a decrease in various physical properties such as the mechanical strength of the film. Furthermore, the content of the impact modifier is preferably 1% by mass or more. By setting the content of the impact modifier to 1% by mass or more, it is possible to reduce the hardness on the surface and easily improve stress relaxation properties, etc.
• the content of the impact modifier is preferably 2.5% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, and more preferably 20% by mass or less, more preferably 16% by mass or less, and even more preferably 12% by mass or less.
• the impact modifier is not contained in the center in the thickness direction of the film (i.e., the intermediate layer (B)), and even if it is contained, it is contained in a content less than that in the surface of the film (i.e., the surface layer (A)).
• the intermediate layer (B) does not contain an impact modifier or contains a small amount of it, the mechanical strength of the present film is easily increased.
• the content of the impact modifier in the intermediate layer (B) should be less than the content of the impact modifier in each of the surface layers (A) based on the mass of each layer, and is preferably less than 4 mass%, more preferably less than 2 mass%, even more preferably 1 mass% or less, even more preferably 0.5 mass% or less, and most preferably 0 mass%.
• the content of impact modifier in the present film is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and even more preferably 5% by mass or less. Furthermore, the content of impact modifier in the entire film is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and even more preferably 1.5% by mass or more.
• the present film may contain particles. By containing particles, the present film can be imparted with properties such as easy slippage, thereby improving the handleability of the film.
• the particles are not particularly limited, but examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, as well as crosslinked polymers such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles, and organic particles such as calcium oxalate and ion exchange resins. Of these, silica and aluminum oxide are preferred, and silica is more preferred.
• the average particle size is generally in the range of 0.05 ⁇ m to 10 ⁇ m, preferably 0.1 ⁇ m to 6 ⁇ m, more preferably 0.3 ⁇ m to 5 ⁇ m, and even more preferably 0.6 ⁇ m to 4.5 ⁇ m.
• the average particle size is the particle size at a cumulative volume fraction of 50% (d50) in the equivalent sphericity distribution measured using a centrifugal sedimentation particle size distribution analyzer.
• the particle content should be within the above range at least in a region from the surface of the film to a depth of 1 ⁇ m in the thickness direction.
• the particle content in the surface layer (A) should be within the above range.
• the particle content relative to the entire film should be within the above range.
• the hardness measured at 23 ⁇ 5° C. with a nanoindenter at the center in the thickness direction of the film is preferably higher than the hardness measured at 23 ⁇ 5° C. with a nanoindenter on one surface of the film.
• Increasing the hardness at the center in this way provides a certain degree of stiffness to the substrate, making it easier to properly hold a wafer when attached to the wafer as a protective sheet.
• it is preferable that the hardness at the central portion measured at 23 ⁇ 5°C using a nanoindenter is higher than the hardness at both surfaces of the film measured at 23 ⁇ 5°C using a nanoindenter.
• the hardness at each position in the thickness direction can be measured by cutting the film along the surface direction using known means to expose each position in the thickness direction of the film, cutting the cross section with a diamond knife or the like to create a smooth surface, and measuring the hardness at each position in the thickness direction of the film using a nanoindenter.
• the film should contain two or more polyesters, and the content of at least one polyester should be adjusted so that it gradually decreases from the surface toward the center, while the content of at least one other polyester should be adjusted so that it gradually increases from the surface toward the center.
• the glass transition temperature (Tg) of the present film is not particularly limited, but is preferably 30°C or higher. When the present film has a Tg of 30°C or higher, the heat resistance of the present film is good.
• the Tg is more preferably 40°C or higher, even more preferably 50°C or higher, and even more preferably 60°C or higher.
• the Tg is preferably set to a certain value or lower, preferably 80°C or lower, more preferably 75°C or lower, even more preferably 73°C or lower, and more preferably 71°C or lower.
• the present film is not particularly limited, but for example, the tensile stress at 5% elongation is preferably 10 MPa or more and 150 MPa or less, more preferably 20 MPa or more and 100 MPa or less, even more preferably 40 MPa or more and 90 MPa or less, and even more preferably 50 MPa or more and 85 MPa or less. Furthermore, although not particularly limited, the tensile stress of the present film at 100% elongation is preferably 20 MPa or more and 200 MPa or less, more preferably 35 MPa or more and 180 MPa or less, even more preferably 50 MPa or more and 160 MPa or less, and even more preferably 90 MPa or more and 150 MPa or less.
• the tensile elongation at break, tensile stress at break, and tensile stress at 5% or 100% elongation of the present film may be measured in both MD and TD and averaged. Details of the measurement methods are as described in the Examples.
• a method for producing a biaxially stretched film As an example of a method for producing the present film, a method for producing a biaxially stretched film will be described below, although the present film is not limited to the method described here.
• the present film is a biaxially stretched polyester film
• the unstretched sheet is preferably obtained by feeding polyester and, if necessary, impact modifiers, particles, and other additives into an extruder, mixing them appropriately, extruding the mixture as a molten sheet from a die using the extruder, and then cooling and solidifying it on a cooling roll.
• the polyesters should be mixed so that they are compatible with each other; specifically, they should be kneaded under conditions of 260 to 300°C, preferably 265 to 295°C, and more preferably 270 to 290°C.
• the unoriented sheet is then stretched in one direction using a roll or tenter type stretching machine at a stretching temperature of usually 25 to 120°C, preferably 35 to 100°C, and at a stretching ratio of usually 2.5 to 7 times, preferably 2.8 to 6 times.
• the film is then stretched in a direction perpendicular to the first stretching direction at a temperature of usually 50 to 140° C. and a stretch ratio of usually 3.0 to 7 times, preferably 3.5 to 6 times.
• a method of stretching in one direction in two or more stages can also be employed.
• the film is subsequently heat-set at a heat-setting temperature of, for example, 130 to 270°C, preferably 165 to 260°C, and more preferably 200 to 240°C, under tension or relaxation of 30% or less, to obtain the present film as a biaxially oriented film.
• Heat-setting the present film can improve its flexibility, heat resistance, and other properties. It also makes it easier to adjust the surface hardness described above.
• the heat-setting is preferably performed at a temperature 5 to 70°C lower than the melting point of the polyester.
• the polyester layers constituting each layer may be co-extruded, and then stretched and heat-set as an integrated film as described above. Whether or not the film has been stretched can be confirmed by measuring the orientation direction and degree of orientation of molecular chains in the film, retardation, etc.
• the present film may be used as a laminate film by laminating another layer on one or both surfaces of the present film.
• a laminate film according to one embodiment of the present invention has the present film described above and a functional layer provided on one or the other surface of the present film.
• the functional layer may include, but is not limited to, a resin layer.
• one resin layer may be provided, or two or more resin layers may be provided.
• Preferred examples of the resin layer include an easy-adhesion layer and an antistatic layer.
• the easy-adhesion layer is a layer provided to adhere other layers or films to the present film, and is not particularly limited to, and may be formed from a binder resin such as a polyurethane resin, a vinyl resin, a polyamide resin, a polyester resin, an acrylic resin, or a polyvinyl acetal resin.
• the resin in the easy-adhesion layer may be appropriately blended with additives such as various crosslinking agents and particles.
• the thickness of the easy-adhesion layer is not particularly limited, but is, for example, from 0.001 ⁇ m to 3 ⁇ m, preferably from 0.005 ⁇ m to 1 ⁇ m, more preferably from 0.01 ⁇ m to 0.5 ⁇ m, and even more preferably from 0.03 ⁇ m to 0.3 ⁇ m.
• the easy-adhesion layer be provided on one surface of the present film whose hardness, measured at 23°C using a nanoindenter, is below a certain value.
• the surface on which the easy-adhesion layer is provided is often provided with an adhesive layer, as described below, and is attached to an adherend such as a wafer or chip. Therefore, by lowering the hardness of the surface on which the easy-adhesion layer is provided as described above, damage to the adherend, such as a wafer or chip, can be effectively prevented when the film is attached to the adherend.
• Compounds having a pyrrolidinium ring are preferably obtained by cyclopolymerizing a diallylamine derivative using a radical polymerization catalyst. Furthermore, a compound having a carbon-carbon unsaturated bond polymerizable with the diallylamine derivative may be used as a copolymerization component.
• conductive polymers are preferred because of their excellent antistatic properties. Examples of conductive polymers include polythiophenes, polyanilines, polypyrroles, and polyacetylenes. Among these, polythiophenes, such as poly(3,4-ethylenedioxythiophene) used in combination with polystyrene sulfonic acid, are preferred.
• the antistatic layer may contain a binder resin in addition to the antistatic agent. The binder resin is as described above. The binder resin may also contain various crosslinking agents, particles, and other additives as appropriate.
• the thickness of the antistatic layer is not particularly limited, but is, for example, 0.001 ⁇ m or more and 3 ⁇ m or less, preferably 0.005 ⁇ m or more and 1 ⁇ m or less, more preferably 0.01 ⁇ m or more and 0.5 ⁇ m or less, and even more preferably 0.02 ⁇ m or more and 0.2 ⁇ m or less.
• the laminate film on which the antistatic layer is provided preferably has a surface resistivity of 1 ⁇ 10 ⁇ / ⁇ or less on the surface on which the antistatic layer is provided.
• the surface resistivity is more preferably 1 ⁇ 10 11 ⁇ / ⁇ or less, and even more preferably 1 ⁇ 10 10 ⁇ / ⁇ or less.
• the surface resistivity is not particularly limited, but may be, for example, 1 ⁇ 10 4 ⁇ / ⁇ or more, or 1 ⁇ 10 5 ⁇ / ⁇ or more.
• a preferred embodiment of the laminated film is one in which an easy-adhesion layer is provided on one surface of the film and an antistatic layer is provided on the other surface. Furthermore, for films provided with a functional layer such as an antistatic layer or easy-adhesion layer, it is preferable that the antistatic layer or easy-adhesion layer is laminated on the film and stretched together with the film. This makes it easier to reduce the thickness of the functional layer through a simple process.
• the laminate film contains an adhesive layer as the resin layer.
• the laminate film becomes an adhesive tape by having the adhesive layer.
• the laminate film can be used by being attached to a wafer or the like, making it suitable for use as a protective tape.
• the adhesive layer is a layer having pressure-sensitive adhesive properties and may be formed from a known adhesive.
• the adhesive is not particularly limited, and conventionally known materials such as acrylic, silicone, urethane, and polyester can be used.
• the adhesive layer may also be UV-curable, and may be cured by UV irradiation to reduce its adhesive strength to the adherend. When the adhesive layer is UV-curable, UV irradiation before peeling the adherend, such as a wafer or chip, improves the releasability when peeling the adherend.
• the adhesive layer may be provided on either surface of the present film, but is preferably provided on one surface of the present film on which the hardness measured at 23°C using a nanoindenter is equal to or less than the above-mentioned certain value. Furthermore, when an easy-adhesion layer is provided on the laminated film, the adhesive layer is preferably laminated on the easy-adhesion layer. By laminating the adhesive layer on the easy-adhesion layer, the adhesive layer is held to the present film with high holding power. A laminated film having an adhesive layer is attached to an adherend such as a wafer via the adhesive layer. By lowering the hardness of the surface of the film on the side where the adhesive layer is provided as described above, the film can appropriately relieve stress when attached to a wafer or the like, effectively preventing damage to the wafer or chip.
• the present film is used in the semiconductor manufacturing process, and is preferably used, for example, as a protective tape that is attached to a wafer to protect the wafer or chips obtained by dividing the wafer.
• semiconductor manufacturing processes include a back-grinding process in which a predetermined circuit pattern is formed on the surface of a semiconductor wafer, followed by a back-grinding process in which the opposite surface of the semiconductor wafer is polished to adjust the thickness of the wafer, a dicing process in which the semiconductor wafer is separated into individual chips, and a pick-up process in which the separated chips are picked up.
• the present film is preferably used as a base material for a protective tape to be adhered to the circuit surface of a semiconductor wafer in any of these processes, and is more preferably used for the back-grinding tape used in the back-grinding process. Since the hardness of one surface of this film is low, by attaching it to a wafer via one surface, stresses such as shear forces acting on the wafer or chip during wafer grinding, etc., can be appropriately alleviated, effectively preventing cracking of the wafer or chip.
• the dicing process may be performed by blade dicing, in which the wafer is cut with a blade, or by stealth dicing.
• Stealth dicing is a method in which a modified layer that serves as the starting point for cutting is formed using laser light, and then external stress is applied to the wafer to separate it into individual chips starting from the modified layer.
• external stress may be applied by an expanding process in which tape attached to the wafer is pulled in the circumferential direction.
• the dicing step is generally performed after a back-grinding step, but it is also preferable to perform it by a so-called dicing-first (DBG) method, in which grooves are formed on the front side of the wafer with a dicing blade, and then the back side of the wafer is ground to reach the grooves, thereby separating the wafer into multiple chips starting from the grooves.
• the first dicing method may be performed by stealth first dicing (SDBG) using laser irradiation, in which a modified layer is formed on the wafer by laser irradiation, and then the modified layer is used as a starting point for separating the wafer into individual chips by back grinding.
• SDBG stealth first dicing
• this film is preferably used as a substrate for backgrinding, but is even more preferably used as a substrate for backgrinding tape used in the dicing-first method.
• chips are singulated and ground simultaneously, making it easy for cracks to occur in the singulated chips during grinding.
• this film has low hardness on one surface and excellent stress relaxation properties, so even when used in the dicing-first method, it can adequately prevent cracking of wafers and chips.
• the term “film” includes the term “sheet”, and the term “sheet” includes the term “film”.
• X to Y X and Y are arbitrary numbers
• it means “X or more and Y or less”, and also means “preferably larger than X” or “preferably smaller than Y”.
• the amount is “X or more” (X is any number)
• it also means that the amount is “preferably greater than X” unless otherwise specified
• the amount is “Y or less” (Y is any number)
• the evaluation and measurement methods are as follows. [Hardness (nano indenter)] The polyester films obtained in each Example, Comparative Example, and Reference Example were cut into 20 mm x 20 mm squares, and the resulting test pieces were attached to glass substrates with wood glue. The hardness of the surface layer (A) side of the test pieces attached to the glass substrate was measured at room temperature (23 ⁇ 5°C) using a nanoindenter "Hysitron TI980 (manufactured by BRUKER)." Specifically, an indentation test was performed on the surface layer (A) side of the resulting test pieces using a diamond Berkovich-type (triangular pyramid-shaped) probe, and a displacement-load hysteresis curve was obtained.
• the indentation test was performed by setting the maximum load so that the contact depth of the probe was approximately 1000 ⁇ 100 nm.
• the process of the nanoindenter indentation test is as follows. (1) To detect the surface of the test piece, the probe is brought close to the surface of the test piece until a predetermined load (2 ⁇ N) is detected. (2) The probe is pulled away from the sample until the load becomes 0 ⁇ N. At this time, if the probe is in contact with the surface of the sample piece, a negative load is detected, and when the probe is completely pulled away from the sample, a flat portion appears in the load-displacement curve. (3) The probe is pushed into and pulled out of the sample.
• the lift height was 100 nm
• the loading time was 5 seconds
• the holding time was 2 seconds
• the unloading time was 5 seconds.
• the Lift Height is the probe separation distance at which the load is reliably 0 ⁇ N in the above (2).
• the load may become 0 ⁇ N when the separation distance reaches the value of the Lift Height, but it is preferable that the load becomes 0 ⁇ N before the separation distance reaches the value of the Lift Height.
• the displacement-load hysteresis curve obtained by the above method was numerically processed using the software (Triboscan 10.2.0.2) provided with the device, and the hardness was calculated. The test was performed at 40 locations (10 ⁇ m intervals), and the average hardness value obtained was used as the hardness.
• the area function required for indenter shape correction during numerical analysis was created using the measurement results of fused quartz.
• Glass transition temperature of polyester film Using a differential scanning calorimeter "DSC8500" (manufactured by PerkinElmer), the glass transition temperature was measured in accordance with JIS K7121:2012 by increasing the temperature from -30°C to 200°C at a rate of 10°C/min, decreasing the temperature to 30°C at a rate of 20°C/min, and then increasing the temperature again to 200°C at a rate of 10°C/min. The glass transition temperature was determined from the midpoint glass transition temperature (Tmg).
• E ⁇ / ⁇ (In the above formula, E is Young's modulus (GPa), ⁇ is the stress difference (GPa) due to the original average cross-sectional area between two points on the line, and ⁇ is the strain difference between the same two points/initial length.) Measurements were taken at five points in each of the machine direction (MD) and the transverse direction (TD) of the film, and the average values were calculated to determine the Young's modulus in MD and the Young's modulus in TD. The average value of the Young's modulus in MD and the Young's modulus in TD was taken as the Young's modulus of the polyester film.
• Tensile breaking stress (MPa) F/A
• F is the load (N) at the time of breakage
• A is the original cross-sectional area (mm 2 ) of the test piece.
• Measurements were taken at five points in each of the machine direction (MD) and the transverse direction (TD) of the film, and the average values were calculated to obtain the tensile stress at break in the MD and the tensile stress at break in the TD.
• the average values of the tensile stress at break in the MD and the tensile stress at break in the TD were used as the tensile stress at break of the polyester film.
• Measurements were taken at five points in each of the machine direction (MD) and the transverse direction (TD) of the film, and the average values were calculated to determine the tensile elongation at break in the MD and the tensile elongation at break in the TD.
• the average value of the tensile elongation at break in the MD and the tensile elongation at break in the TD was determined to be the tensile elongation at break of the polyester film.
• Measurements were taken at five points in each of the longitudinal direction (MD) and transverse direction (TD) of the film, and the average values were calculated for each to determine the tensile stress at 5% elongation in the MD and the tensile stress at 5% elongation in the TD.
• the average value of the tensile stress at 5% elongation in the MD and the tensile stress at 5% elongation in the TD was determined to be the tensile stress at 5% elongation of the polyester film.
• the load (N) at 100% elongation was also measured in the same manner, and the tensile stress at 100% elongation was determined in the same manner as the tensile stress at 5% elongation.
• Copolymer polyester (1) Thermoplastic polyester Copolymer polyester (1) was prepared, which contained terephthalic acid and adipic acid (having 6 carbon atoms) as dicarboxylic acid components, with the terephthalic acid content being 85 mol % and the adipic acid content being 15 mol %, and which contained 45 mol % of 1,4-butanediol and 55 mol % of 1,6-hexanediol as diol components.
• Copolymer polyester (2) Thermoplastic polyester Copolymer polyester (2) (intrinsic viscosity (IV) 0.70 dl/g) was prepared, which contained terephthalic acid and isophthalic acid as dicarboxylic acid components, with the terephthalic acid content being 78 mol % and the isophthalic acid content being 22 mol %, and which contained ethylene glycol 98 mol % and diethylene glycol 2 mol % as diol components.
• IV intrinsic viscosity
• Thermoplastic polyester Copolymer polyester (3) was prepared, in which the dicarboxylic acid component was terephthalic acid, ethylene glycol was 68 mol %, and 1,4-cyclohexanedimethanol (CHDM) was 32 mol %.
• Homopolyester (1) Thermoplastic polyester A particle-containing homopolyester (1) (particle-containing homoPET) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and diol components of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.62 dl/g and contained 0.55 mass % silica particles having an average particle size of 3 ⁇ m.
• particle-containing homoPET was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and diol components of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.62 dl/g and contained 0.55 mass % silica particles having an average particle size of 3 ⁇ m.
• Homopolyester (2) Thermoplastic polyester A homopolyester (2) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and a diol component of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.645 dl/g.
• Homopolyester (3) Thermoplastic polyester A particle-containing homopolyester (3) (particle-containing homoPET) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and diol components of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.590 dl/g and contained 0.7 mass % silica particles having an average particle size of 3 ⁇ m.
• IV intrinsic viscosity
• Homopolyester (4) Thermoplastic polyester A homopolyester (4) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and a diol component of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.7 dl/g.
• Homopolyester (5) Thermoplastic polyester A particle-containing homopolyester (5) (particle-containing homoPET) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and diol components of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.65 dL/g and contained 0.6 mass % silica particles having an average particle size of 3 ⁇ m.
• IV intrinsic viscosity
• Homopolyester (6) Thermoplastic polyester A homopolyester (4) was prepared, which was a polyester having a dicarboxylic acid component of terephthalic acid and a diol component of 98 mol % ethylene glycol and 2 mol % diethylene glycol, and had an intrinsic viscosity (IV) of 0.580 dl/g.
• Impact modifier Maleic anhydride-modified hydrogenated styrene-based thermoplastic elastomer (SEBS), manufactured by Asahi Kasei Chemicals Corporation, "Tuftec M1943"
• Example 1 As shown in Table 1, as the raw materials for the surface layer (A), 38 parts by mass of copolymer polyester (1), 42 parts by mass of polyarylate, 10 parts by mass of homopolyester (1), and 10 parts by mass of impact resistance modifier were dry blended, and as the raw materials for the intermediate layer (B), 10 parts by mass of copolymer polyester (2) and 90 parts by mass of homopolyester (2) were dry blended.
• the mixed raw materials for the surface layer (A) and the intermediate layer (B) were each fed into separate twin-screw extruders, kneaded at 285°C, and co-extruded at 285°C.
• the materials were then cooled and solidified on a cooling roll set at 25°C using an electrostatic adhesion method, thereby obtaining an unstretched film with two types and three layers (surface layer (A)/intermediate layer (B)/surface layer (A)).
• the resulting unstretched film was then stretched 3 times in the machine direction (MD) at 65°C using a roll stretching machine.
• a coating solution for an easy-adhesion layer solid content concentration: 9.0% by mass
• solid content concentration: 9.0% by mass having the following formulation was applied to one side of the polyester film by in-line coating, and the coating solution was applied to one side of the polyester film so that the thickness after drying and stretching would be as shown in Table 1, forming an easy-adhesion layer.
• the film was then introduced into a tenter stretching machine and stretched to 3.1°C in the transverse direction (TD). Subsequently, the film was subjected to a heat setting treatment at a heat setting temperature of 210°C for 7 seconds, and a cooling treatment to 140°C under 2.5% relaxation in the transverse direction (TD) to obtain a polyester film having a thickness of 80 ⁇ m (each surface layer (A): 8 ⁇ m, intermediate layer (B): 64 ⁇ m).
• Example 3 After the coating liquid for the easy-adhesion layer was applied and before the transverse stretching, a coating liquid for the antistatic layer (2) (solid content concentration: 2.8 mass %) having the following formulation was further applied to the other surface of the polyester film, and the coating liquid was applied to the other surface of the polyester film so as to have a thickness shown in Table 1 after drying and stretching, thereby forming an antistatic layer (2), as in Example 1.
• Conductive agent "Orgacon ICP1010” manufactured by Agfa-Gevaert), whose main components are polyethylenedioxythiophene and polystyrene sulfonic acid, was neutralized with concentrated aqueous ammonia to a pH of 9.
• Example 4 As shown in Table 1, the raw materials for the surface layer (A) were a dry blend of 27 parts by mass of copolymer polyester (1), 10 parts by mass of homopolyester (1), 53 parts by mass of homopolyester (2), and 10 parts by mass of an impact resistance modifier, and the same procedures were carried out as in Example 1 except that the kneading temperature and extrusion temperature were changed to 280°C, the heat setting temperature was changed to 230°C, and the thickness was changed to 77 ⁇ m (each surface layer (A): 7.7 ⁇ m, intermediate layer (B): 61.6 ⁇ m).
• Example 5 The same procedure as in Example 4 was carried out, except that after the coating liquid for the easy-adhesion layer and before the transverse stretching, the above-mentioned coating liquid for the antistatic layer (1) (solid content concentration: 3.3 mass %) was further coated on the other side of the polyester film, and the coating liquid was coated on the other side of the polyester film so as to have a thickness shown in Table 1 after drying and stretching, thereby forming an antistatic layer (1).
• Example 8 a polyester film having a single layer structure was produced. As shown in Table 2, 85 parts by mass of copolymer polyester (2), 10 parts by mass of homopolyester (4), and 5 parts by mass of homopolyester (5) were dry blended as raw materials. The mixed raw materials were charged into a twin-screw extruder, kneaded at 280°C, extruded at 280°C, and cooled and solidified on a cooling roll set at 16°C using an electrostatic adhesion method, to obtain an unstretched film having a single layer structure. The resulting unstretched film was then stretched 3.4 times in the machine direction (MD) at 81°C using a roll stretching machine.
• MD machine direction
• Example 9 As shown in Table 2, the same procedure as in Example 8 was repeated except that a dry blend of 40 parts by mass of copolymer polyester (2), 5 parts by mass of homopolyester (5), and 55 parts by mass of copolymer polyester (3) was used as raw materials, and the heat setting temperature was changed to 169°C.
• the materials were then cooled and solidified on a cooling roll set at 20°C using an electrostatic adhesion method, thereby obtaining an unstretched film with two types and three layers (surface layer (A)/intermediate layer (B)/surface layer (A)).
• the unstretched film was then stretched 3.4 times in the machine direction (MD) at 90°C using a roll stretching machine. It was then introduced into a tenter stretching machine and stretched 4.3 times in the transverse direction (TD) at 145°C.

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