Semiconductor wafer supporting sheet and laminate

Abstract

A semiconductor wafer supporting sheet including a support layer containing a liquid crystal polyester having a melting point of 250°C or higher.

Description

Sheets and laminates for supporting semiconductor wafers

[0001] This disclosure relates to semiconductor wafer support sheets and laminates.

[0002] Conventionally, in order to make semiconductor chips thinner, a process has been carried out in the semiconductor chip manufacturing process in which one side of the semiconductor wafer is supported by a backgrind sheet and the other side of the semiconductor wafer is ground. For example, Patent Document 1 discloses a semiconductor processing adhesive tape that is attached to the surface of a semiconductor wafer and used in a process in which grooves are formed on the surface of the semiconductor wafer or modified regions are formed on the semiconductor wafer, and the back surface of the semiconductor wafer is ground to separate the semiconductor wafer into semiconductor chips by the grinding.

[0003] International Publication No. 2017 / 150675

[0004] In recent years, semiconductor chips have been used in a wide range of fields, and various forms in terms of material, shape, and thickness are being considered. Therefore, a diverse range of options is required for the semiconductor wafer grinding process, and consequently, for the sheets that support the semiconductor wafers during the grinding process. For example, there is a need for semiconductor wafer support sheets that can maintain good functionality even when exposed to high temperatures during the grinding process.

[0005] This disclosure aims to provide a novel semiconductor wafer support sheet. Furthermore, this disclosure aims to provide a laminate comprising the semiconductor wafer support sheet and a semiconductor wafer.

[0006] This disclosure provides, for example, the following: [1] A semiconductor wafer support sheet comprising a support layer containing a liquid crystal polyester having a melting point of 250°C or higher. [2] The support layer is an extruded molded body of a resin composition containing liquid crystal polyester, wherein the coefficient of linear expansion of the extruded molded body in the TD direction is (×10 －５ (1 / K) and the coefficient of linear expansion in the MD direction (×10 －５ The absolute value of the difference between (1 / K) is 15 (×10 －５A semiconductor wafer support sheet according to [1], wherein the (1 / K) ratio is less than or equal to [3]. A semiconductor wafer support sheet according to [1] or [2], wherein the liquid crystal polyester comprises a first monomer unit having a condensed aromatic ring and a second monomer unit having a benzene ring and not having a condensed aromatic ring. A laminate comprising a semiconductor wafer and a semiconductor wafer support sheet according to any one of [1] to [3] laminated on one surface of the semiconductor wafer.

[0007] This disclosure provides a novel semiconductor wafer support sheet. Furthermore, this disclosure provides a laminate comprising the semiconductor wafer support sheet and a semiconductor wafer.

[0008] Figure 1 shows one form of the laminate. Figure 2 shows another form of the laminate.

[0009] Preferred embodiments of this disclosure are described in detail below.

[0010] <Semiconductor wafer support sheet> The semiconductor wafer support sheet of this embodiment comprises a support layer containing liquid crystal polyester having a melting point of 250°C or higher.

[0011] The semiconductor wafer support sheet of this embodiment has good heat resistance because the liquid crystal polyester in the support layer has a melting point of 250°C or higher, and can maintain its good function as a semiconductor wafer support sheet even when exposed to high temperatures during processes such as semiconductor wafer grinding.

[0012] Furthermore, because liquid crystal polyester has excellent mechanical strength and dimensional stability, in this embodiment the support layer can firmly support the semiconductor wafer and suppress cracking and warping of the semiconductor wafer.

[0013] (Liquid Crystal Polyester) Liquid crystal polyester can be any polyester that exhibits liquid crystallinity in a molten state. Liquid crystal polyester may be a single polymer or a mixture of two or more polymers. When liquid crystal polyester is a mixture of two or more polymers, the content of each monomer unit described below represents the total amount of each monomer unit in the mixture. Also, when liquid crystal polyester is a mixture of two or more polymers, the parameters relating to liquid crystal polyester described below represent the parameters of the mixture (parameters measured using the mixture). The mixture used for measurement may be, for example, a mixture of powders of two or more polymers that have been granulated and pelletized. Furthermore, the total number of monomer units represents the total number of monomer units constituting each polymer.

[0014] Liquid crystal polyesters have constituent units (monomer units) derived from raw material monomers. In liquid crystal polyesters, the main monomer units (for example, monomer units that make up 90 mol% or more, 95 mol% or more, or 99 mol% or more of the total monomer units, preferably all monomer units) may be monomer units having an aromatic ring, i.e., monomer units derived from aromatic compounds. Liquid crystal polyesters in which all monomer units are monomer units derived from aromatic compounds are also called all-aromatic liquid crystal polyesters.

[0015] In this specification, "derived from" means that in the monomer units of the liquid crystal polyester formed by the polymerization of the raw material monomers, the chemical structure of the functional groups that contribute to polymerization of the raw material monomers has changed, while no other structural changes have occurred. Here, "derived from" is a concept that also includes cases where the product is derived from polymerizable derivatives of the raw material monomers (for example, compounds obtained by converting the functional groups that contribute to polymerization of the raw material monomers into other polymerizable groups).

[0016] Aromatic compounds are compounds having an aromatic ring. Suitable aromatic compounds as starting monomers may have an aromatic ring and two or more polymerizable groups bonded to the aromatic ring (for example, polymerizable groups selected from the group consisting of hydroxyl groups, amino groups, and carboxyl groups, preferably polymerizable groups selected from the group consisting of hydroxyl groups and carboxyl groups).

[0017] The aromatic compound may be, for example, a compound represented by the following formula (1-1) (hereinafter also referred to as monomer (1-1)), a compound represented by the following formula (1-2) (hereinafter also referred to as monomer (1-2)), or a compound represented by the following formula (1-3) (hereinafter also referred to as monomer (1-3)). X １ -Ar １ -Y １ (1-1) X ２ -Ar ２ -X ３ (1-2) Y ２ -Ar ３ -Y ３ (1-3) [In the formula, Ar １ , Ar ２ and Ar ３ each independently represent a phenylene group, a biphenylylene group, a condensed polycyclic aromatic hydrocarbon group, or a group represented by formula (Z-1). Ar １ , Ar ２ and Ar ３ may have some or all of the hydrogen atoms thereof substituted with a halogeno group, an alkyl group, or an aryl group. X １ , X ２ and X ３ each independently represent a hydroxy group or an amino group. Y １ , Y ２ and Y ３ each represent a carboxy group. ] -Ar ４ -Z １ -Ar ５ - (Z-1) [In the formula, Ar ４ and Ar ５ each independently represent a phenylene group or a condensed polycyclic aromatic hydrocarbon group. Z １ represents an oxygen atom (-O-), a sulfur atom (-S-), a carbonyl group (-CO-), a sulfonyl group (-SO ２ -) or an alkanediyl group. ]

[0018] Monomeric units derived from aromatic compounds may be, for example, the monomer unit represented by the following formula (2-1) (hereinafter also referred to as monomer unit (2-1)), the constituent unit represented by the following formula (2-2) (hereinafter also referred to as monomer unit (2-2)), or the constituent unit represented by the following formula (2-3) (hereinafter also referred to as monomer unit (2-3)). It can be said that monomer unit (2-1) is a monomer unit derived from monomer (1-1), monomer unit (2-2) is a monomer unit derived from monomer (1-2), and monomer unit (2-3) is a monomer unit derived from monomer (1-3). -X １１ -Ar １ -Y １１ - (2-1) -X １２ -Ar ２ -X １３ - (2-2) - Y １２ -Ar ３ -Y １３ - (2-3) [wherein, Ar １ Ar ２ and Ar ３ This is synonymous with the above. X １１ , X １２ and X １３ Each of these independently represents either an oxygen atom (-O-) or an imino group (-NH-). １１ , Y １２ and Y １３ This represents a carbonyl group (-CO-).

[0019] The phenylene group may be, for example, a 1,4-phenylene group or a 1,3-phenylene group, and is preferably a 1,4-phenylene group.

[0020] The biphenylylene group may be, for example, a 4,4'-biphenylylene group.

[0021] A condensed polycyclic aromatic hydrocarbon group is a group obtained by removing two hydrogen atoms from a condensed polycyclic aromatic hydrocarbon. Examples of condensed polycyclic aromatic hydrocarbons include naphthalene, anthracene, phenanthrene, tetracene, pyrene, triphenylene, perylene, and fluorene. Of these, naphthalene is preferred from the viewpoint of availability and price.

[0022] The condensed polycyclic aromatic hydrocarbon group may be, for example, a naphthylene group. The naphthylene group may be, for example, a 2,6-naphthylene group, a 2,7-naphthylene group, or a 1,5-naphthylene group, and is preferably a 2,6-naphthylene group.

[0023] Examples of halogen groups as substituents include fluoro groups (-F), chloro groups (-Cl), bromo groups (-Br), and iodine groups (-I). The halogen group as substituent may be a fluoro group, a chloro group, or a bromo group, or it may be a fluoro group, a chloro group, or it may be a fluoro group.

[0024] The alkyl group as a substituent may be linear, branched, or cyclic. The alkyl group may be, for example, an alkyl group having 1 to 10 carbon atoms. Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, and the like.

[0025] The aryl group as a substituent may be monocyclic, polycyclic, or fused. The aryl group may be, for example, an aryl group having 6 to 20 carbon atoms. Examples of aryl groups include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl, and 2-naphthyl groups. The aryl group may also be a group in which a hydrogen atom of the aromatic ring is substituted with an alkyl group, such as the tolyl group.

[0026] Ar １ Ar ２ and Ar ３ The number of substituents on the compound may be, for example, 0 to 2, 0 or 1, or 0.

[0027] Z １ The alkanediyl group in may be linear or branched. The alkanediyl group may be an alkanediyl group having 1 to 10 carbon atoms. Examples of alkanediyl groups include a methylene group, an ethanediyl group, a propanediyl group (e.g., a propane-2,2-diyl group), a butanediyl group, an octanediyl group (e.g., an octane-3,3-diyl group), and the like.

[0028] Z １ The group is preferably an oxygen atom, a sulfur atom, a methylene group, an ethanediyl group, or a propanediyl group, and more preferably an oxygen atom.

[0029] X １ , X ２ and X ３ is preferably a hydroxyl group, X １１ , X １２ and X １３ Preferably, this is an oxygen atom (-O-). That is, monomer (1-1) may be an aromatic hydroxycarboxylic acid, monomer (1-2) may be an aromatic diol, and monomer (1-3) may be an aromatic dicarboxylic acid.

[0030] The liquid crystal polyester may, for example, contain a first monomer unit having a condensed aromatic ring.

[0031] Examples of condensed aromatic rings possessed by the first monomer unit include naphthalene rings, anthracene rings, phenanthrene rings, tetracene rings, pyrene rings, triphenylene rings, perylene rings, and fluorene rings. Of these, naphthalene rings are preferred from the viewpoint of availability and price.

[0032] The first monomer unit may be a monomer unit corresponding to monomer unit (2-1), a monomer unit corresponding to monomer unit (2-2), or a monomer unit corresponding to monomer unit (2-3). For example, the first monomer unit may be a monomer unit corresponding to monomer unit (2-1) or monomer unit (2-3).

[0033] The first monomer unit is, for example, Ar １ It may also be a monomer unit (2-1) (hereinafter also called monomer unit (2-1-1)) in which Ar is a condensed polycyclic aromatic hydrocarbon group, ２ It may also be a monomer unit (2-2) (hereinafter also called monomer unit (2-2-1)) in which Ar is a condensed polycyclic aromatic hydrocarbon group, ３The monomer unit (2-3) (hereinafter also referred to as monomer unit (2-3-1)) may be a condensed polycyclic aromatic hydrocarbon group. In the first monomer unit, the condensed polycyclic aromatic hydrocarbon group is preferably a naphthylene group, and more preferably a 2,6-naphthylene group.

[0034] The first monomer unit can also be described as a monomer unit derived from the first monomer having a condensed aromatic ring.

[0035] The first monomer may be the monomer corresponding to monomer (1-1), the monomer corresponding to monomer (1-2), or the monomer corresponding to monomer (1-3). The first monomer may be, for example, the monomer corresponding to monomer (1-1) or monomer (1-3).

[0036] The first monomer is, for example, Ar １ It may also be a monomer (1-1) (hereinafter also referred to as monomer (1-1-1)) in which Ar is a condensed polycyclic aromatic hydrocarbon group, ２ It may also be a monomer (1-2) (hereinafter also called monomer (1-2-1)) in which Ar is a condensed polycyclic aromatic hydrocarbon group, ３ The monomer (1-3) (hereinafter also referred to as monomer (1-3-1)) may be a condensed polycyclic aromatic hydrocarbon group. In the first monomer, the condensed polycyclic aromatic hydrocarbon group is preferably a naphthylene group, and more preferably a 2,6-naphthylene group.

[0037] Examples of the first monomer include 2-hydroxy-6-naphthoic acid, 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, and 2,7-naphthalenediol. 2-hydroxy-6-naphthoic acid and 2,6-naphthalenedicarboxylic acid are preferred as the first monomer.

[0038] The liquid crystal polyester may further contain, for example, a second monomer unit having a benzene ring but not a condensed aromatic ring.

[0039] The second monomer unit may be a monomer unit corresponding to monomer unit (2-1), a monomer unit corresponding to monomer unit (2-2), or a monomer unit corresponding to monomer unit (2-3).

[0040] The second monomer unit is, for example, Ar １ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (however, Ar ４ and Ar ５ It may also be a monomer unit (2-1) (hereinafter also called monomer unit (2-1-2)) which is a phenylene group, Ar ２ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (however, Ar ４ and Ar ５ It may also be a monomer unit (2-2) (hereinafter also called monomer unit (2-2-2)) which is a phenylene group, Ar ３ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (however, Ar ４ and Ar ５ The monomer unit (2-3) (hereinafter also referred to as monomer unit (2-3-2)) is a phenylene group. In the second monomer unit, Ar １ Ar ２ and Ar ３ The group is preferably a phenylene group or a biphenylylene group, more preferably a 1,4-phenylene group, a 1,3-phenylene group or a 4,4'-biphenylylene group, and even more preferably a 1,4-phenylene group or a 4,4'-biphenylylene group.

[0041] The second monomer unit can also be described as a monomer unit derived from a second monomer that has a benzene ring but lacks a condensed aromatic ring.

[0042] The second monomer may be the monomer corresponding to monomer (1-1), the monomer corresponding to monomer (1-2), or the monomer corresponding to monomer (1-3).

[0043] The second monomer is, for example, Ar １ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (however, Ar４ and Ar ５ is a phenylene group) may be the monomer (1-1) (hereinafter also referred to as monomer (1-1-2)), and Ar ２ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (provided that Ar ４ and Ar ５ is a phenylene group) may be the monomer (1-2) (hereinafter also referred to as monomer (1-2-2)), and Ar ３ is a phenylene group, a biphenylylene group, or a group represented by formula (Z-1) (provided that Ar ４ and Ar ５ is a phenylene group) may be the monomer (1-3) (hereinafter also referred to as monomer (1-3-2)). In the second monomer, Ar １ , Ar ２ and Ar ３ is preferably a phenylene group or a biphenylylene group, more preferably a 1,4-phenylene group, a 1,3-phenylene group or a 4,4'-biphenylylene group, and still more preferably a 1,4-phenylene group or a 4,4'-biphenylylene group.

[0044] Examples of the second monomer include p-hydroxybenzoic acid, m-hydroxybenzoic acid, hydroquinone, 4,4'-biphenol, terephthalic acid, and isophthalic acid. The second monomer is preferably p-hydroxybenzoic acid, hydroquinone, 4,4'-biphenol, or terephthalic acid.

[0045] The liquid crystal polyester may have monomer units other than the monomer unit (2-1), the monomer unit (2-2) and the monomer unit (2-3), and the content thereof may be, for example, 10 mol% or less, 5 mol% or less, 3 mol% or less, 1 mol% or less, or 0 mol%, relative to the total of all monomer units. That is, in the liquid crystal polyester, the total content of the monomer unit (2-1), the monomer unit (2-2) and the monomer unit (2-3) may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, 99 mol% or more, or 100 mol%, relative to the total of all monomer units.

[0046] Liquid crystal polyester may contain monomers other than the first monomer unit and the second monomer unit, but the content of these monomers may be, for example, 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less, or 0 mol%, relative to the total amount of all monomer units. That is, in liquid crystal polyester, the total content of the first monomer unit and the second monomer unit may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, or 100 mol%, relative to the total amount of all monomer units.

[0047] Liquid crystal polyester may be mainly composed of monomer units (2-1), for example, or may include monomer units (2-1), monomer units (2-2), and monomer units (2-3).

[0048] When the liquid crystal polyester is mainly composed of monomer units (2-1), the content of monomer units (2-1) may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, or 100 mol%, relative to the total amount of all monomer units.

[0049] When the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the total content of monomer units (2-1), monomer units (2-2), and monomer units (2-3) may be, for example, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more, or 100 mol%, relative to the total amount of all monomer units.

[0050] When the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the content of monomer unit (2-2) and the content of monomer unit (2-3) may be approximately the same (for example, the difference may be 3 mol% or less, 1 mol% or less, 0.5 mol% or less, or 0.1 mol% or less).

[0051] When the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the content of monomer unit (2-1) may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, relative to the total amount of monomer units. Also, when the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the content of monomer unit (2-1) may be, for example, 90 mol% or less, 80 mol% or less, 70 mol% or less, or 60 mol% or less, relative to the total amount of monomer units. That is, when the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the content of monomer unit (2-1) may be, for example, 10-90 mol%, 10-80 mol%, 10-70 mol%, 10-60 mol%, 20-90 mol%, 20-80 mol%, 20-70 mol%, 20-60 mol%, 30-90 mol%, 30-80 mol%, 30-70 mol%, 30-60 mol%, 40-90 mol%, 40-80 mol%, 40-70 mol%, 40-60 mol%, 50-90 mol%, 50-80 mol%, 50-70 mol%, or 50-60 mol% relative to the total amount of monomer units.

[0052] When the liquid crystal polyester contains monomer units (2-1), (2-2), and (2-3), the content of monomer unit (2-2) and the total content of monomer unit (2-3) may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, or 40 mol% or more, relative to the total of all monomer units. Furthermore, when the liquid crystal polyester contains monomer units (2-1), (2-2), and (2-3), the content of monomer unit (2-2) and the total content of monomer unit (2-3) may be, for example, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less, relative to the total of all monomer units. That is, when the liquid crystal polyester contains monomer units (2-1), monomer units (2-2), and monomer units (2-3), the content of monomer unit (2-2) and the total content of monomer units (2-3) may be, for example, 10-90 mol%, 10-80 mol%, 10-70 mol%, 10-60 mol%, 10-50 mol%, 20-90 mol%, 20-80 mol%, 20-70 mol%, 20-60 mol%, 20-50 mol%, 30-90 mol%, 30-80 mol%, 30-70 mol%, 30-60 mol%, 30-50 mol%, 40-90 mol%, 40-80 mol%, 40-70 mol%, 40-60 mol%, or 40-50 mol% relative to the total amount of monomer units.

[0053] The content of the first monomer unit in the liquid crystal polyester may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, or 70 mol% or more, relative to the total amount of all monomer units. A higher content of the first monomer unit tends to result in a higher flow initiation temperature and better support of semiconductor wafers at high temperatures. The content of the first monomer unit may be, for example, 90 mol% or less, 85 mol% or less, or 80 mol% or less, relative to the total amount of all monomer units. A lower content of the first monomer unit tends to result in better moldability of the semiconductor wafer support sheet. In other words, the content of the first monomer unit in the liquid crystal polyester may be, for example, 10-90 mol%, 10-85 mol%, 10-80 mol%, 20-90 mol%, 20-85 mol%, 20-80 mol%, 30-90 mol%, 30-85 mol%, 30-80 mol%, 40-90 mol%, 40-85 mol%, 40-80 mol%, 50-90 mol%, 50-85 mol%, 50-80 mol%, 60-90 mol%, 60-85 mol%, 60-80 mol%, 70-90 mol%, 70-85 mol%, or 70-80 mol% relative to the total amount of all monomer units.

[0054] When the liquid crystal polyester contains a second monomer unit, the content of the second monomer unit may be, for example, 10 mol% or more, 15 mol% or more, or 20 mol% or more, relative to the total amount of all monomer units. A higher content of the second monomer unit tends to result in better processability of the semiconductor wafer support sheet. The content of the second monomer unit may be, for example, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, or 30 mol% or less, relative to the total amount of all monomer units. In other words, when the liquid crystal polyester contains a second monomer unit, the content of the second monomer unit may be, for example, 10-90 mol%, 10-80 mol%, 10-70 mol%, 10-60 mol%, 10-50 mol%, 10-40 mol%, 10-30 mol%, 15-90 mol%, 15-80 mol%, 15-70 mol%, 15-60 mol%, 15-50 mol%, 15-40 mol%, 15-30 mol%, 20-90 mol%, 20-80 mol%, 20-70 mol%, 20-60 mol%, 20-50 mol%, 20-40 mol%, or 20-30 mol% relative to the total amount of all monomer units.

[0055] The liquid crystal polyester may contain, as the first monomer unit, at least one selected from the group consisting of monomer unit (2-1-1), monomer unit (2-2-1), and monomer unit (2-3-1), and may contain at least one selected from the group consisting of monomer unit (2-1-1) and monomer unit (2-3-1). Furthermore, it is preferable that the liquid crystal polyester contains at least monomer unit (2-1-1) as the first monomer unit.

[0056] The liquid crystal polyester may contain at least one selected from the group consisting of monomer units (2-1-2), monomer units (2-2-2), and monomer units (2-3-2) as the second monomer unit. In one embodiment, the liquid crystal polyester may mainly contain monomer unit (2-1-2) as the second monomer unit. That is, in one embodiment, the proportion of monomer unit (2-1-2) in the second monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%. In another embodiment, the liquid crystal polyester may mainly contain monomer units (2-2-2) and monomer units (2-3-2) as the second monomer unit. That is, in another embodiment, the total proportion of monomer units (2-2-2) and monomer units (2-3-2) in the second monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%.

[0057] In the first embodiment, the liquid crystal polyester may include monomer unit (2-1-1) as the first monomer unit and monomer unit (2-1-2) as the second monomer unit.

[0058] In the first embodiment, the proportion of monomer units (2-1-1) to the first monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%.

[0059] In the first embodiment, the proportion of monomer units (2-1-2) in the second monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%.

[0060] In the first embodiment, the content of monomer units (2-1-1) may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, or 70 mol% or more, based on the total amount of monomer units. Also in the first embodiment, the content of monomer units (2-1-1) may be, for example, 90 mol% or less, 85 mol% or less, or 80 mol% or less, based on the total amount of monomer units. That is, in the first embodiment, the content of monomer units (2-1-1) may be, for example, 10-90 mol%, 10-85 mol%, 10-80 mol%, 20-90 mol%, 20-85 mol%, 20-80 mol%, 30-90 mol%, 30-85 mol%, 30-80 mol%, 40-90 mol%, 40-85 mol%, 40-80 mol%, 50-90 mol%, 50-85 mol%, 50-80 mol%, 60-90 mol%, 60-85 mol%, 60-80 mol%, 70-90 mol%, 70-85 mol%, or 70-80 mol% relative to the total amount of monomer units.

[0061] In the first embodiment, the content of monomer units (2-1-2) may be, for example, 10 mol% or more, 15 mol% or more, or 20 mol% or more, based on the total amount of monomer units. Also in the first embodiment, the content of monomer units (2-1-2) may be, for example, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, or 30 mol% or less, based on the total amount of monomer units. That is, in the first embodiment, the content of monomer units (2-1-2) may be, for example, 10-90 mol%, 10-80 mol%, 10-70 mol%, 10-60 mol%, 10-50 mol%, 10-40 mol%, 10-30 mol%, 15-90 mol%, 15-80 mol%, 15-70 mol%, 15-60 mol%, 15-50 mol%, 15-40 mol%, 15-30 mol%, 20-90 mol%, 20-80 mol%, 20-70 mol%, 20-60 mol%, 20-50 mol%, 20-40 mol%, or 20-30 mol% relative to the total amount of monomer units.

[0062] In the first monomer, the total content of monomer units (2-1-1) and monomer units (2-1-2) may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol% of the total amount of monomer units.

[0063] In a second embodiment, the liquid crystal polyester may include monomer units (2-1-1) and (2-3-1) as first monomer units, and monomer units (2-2-2) and (2-3-2) as second monomer units.

[0064] In the second embodiment, the total proportion of monomer units (2-1-1) and monomer units (2-3-1) in the first monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%.

[0065] In the second embodiment, the total proportion of monomer units (2-2-2) and monomer units (2-3-2) in the second monomer unit may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol%.

[0066] In the second embodiment, the total content of monomer units (2-1-1), monomer units (2-3-1), monomer units (2-2-2), and monomer units (2-3-2) may be, for example, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, or 100 mol% of the total amount of monomer units.

[0067] In a second embodiment, the content of monomer units (2-1-1) may be, for example, 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, or 50 mol% or more, relative to the total amount of monomer units. Also in a second embodiment, the content of monomer units (2-1-1) may be, for example, 90 mol% or less, 80 mol% or less, 70 mol% or less, or 60 mol% or less, relative to the total amount of monomer units. That is, in the second embodiment, the content of monomer units (2-1-1) may be, for example, 10-90 mol%, 10-80 mol%, 10-70 mol%, 10-60 mol%, 20-90 mol%, 20-80 mol%, 20-70 mol%, 20-60 mol%, 30-90 mol%, 30-80 mol%, 30-70 mol%, 30-60 mol%, 40-90 mol%, 40-80 mol%, 40-70 mol%, 40-60 mol%, 50-90 mol%, 50-80 mol%, 50-70 mol%, or 50-60 mol% relative to the total amount of monomer units.

[0068] In a second embodiment, the content of monomer units (2-3-1) may be, for example, 3 mol% or more, 5 mol% or more, 10 mol% or more, or 15 mol% or more, relative to the total amount of monomer units. Also in a second embodiment, the content of monomer units (2-3-1) may be, for example, 40 mol% or less, 30 mol% or less, or 20 mol% or less, relative to the total amount of monomer units. That is, in a second embodiment, the content of monomer units (2-3-1) may be, for example, 3 to 40 mol%, 3 to 30 mol%, 3 to 20 mol%, 5 to 40 mol%, 5 to 30 mol%, 5 to 20 mol%, 10 to 40 mol%, 10 to 30 mol%, 10 to 20 mol%, 15 to 40 mol%, 15 to 30 mol%, or 15 to 20 mol%, relative to the total amount of monomer units.

[0069] In a second embodiment, the content of monomer units (2-2-2) may be, for example, 3 mol% or more, 5 mol% or more, 10 mol% or more, or 15 mol% or more, relative to the total amount of monomer units. Also in a second embodiment, the content of monomer units (2-2-2) may be, for example, 40 mol% or less, 30 mol% or less, or 20 mol% or less, relative to the total amount of monomer units. That is, in a second embodiment, the content of monomer units (2-2-2) may be, for example, 3 to 40 mol%, 3 to 30 mol%, 3 to 20 mol%, 5 to 40 mol%, 5 to 30 mol%, 5 to 20 mol%, 10 to 40 mol%, 10 to 30 mol%, 10 to 20 mol%, 15 to 40 mol%, 15 to 30 mol%, or 15 to 20 mol%, relative to the total amount of monomer units.

[0070] In the second embodiment, the content of monomer units (2-3-2) may be, for example, 1 mol% or more, 2 mol% or more, or 3 mol% or more. Also in the second embodiment, the content of monomer units (2-3-2) may be, for example, 20 mol% or less, 15 mol% or less, or 10 mol% or less. That is, in the second embodiment, the content of monomer units (2-3-2) may be, for example, 1 to 20 mol%, 1 to 15 mol%, 1 to 10 mol%, 2 to 20 mol%, 2 to 15 mol%, 2 to 10 mol%, 3 to 20 mol%, 3 to 15 mol%, or 3 to 10 mol%.

[0071] In this specification, the number of each monomer unit in a liquid crystal polyester is determined by the analytical method described in Japanese Patent Application Publication No. 2000-19168. Specifically, the number of each monomer unit relative to the total number of monomer units can be calculated by depolymerizing the liquid crystal polyester by reacting it with a lower alcohol in a supercritical state and quantifying the depolymerization product (monomers that induce each monomer unit) by liquid chromatography.

[0072] Liquid crystal polyester can be produced by polymerizing raw material monomers corresponding to the monomer units that constitute it. For example, it can be produced according to the method described in Japanese Patent No. 6439027.

[0073] In this embodiment, the melting point (Tm) of the liquid crystal polyester is 250°C or higher, and may be 270°C or higher, 280°C or higher, 300°C or higher, or 310°C or higher. Alternatively, the melting point (Tm) of the liquid crystal polyester may be, for example, 380°C or lower, or 350°C or lower. That is, the melting point (Tm) of the liquid crystal polyester may be, for example, 250°C to 380°C, 250°C to 350°C, 270°C to 380°C, 270°C to 350°C, 280°C to 380°C, 280°C to 350°C, 300°C to 380°C, 300°C to 350°C, 310°C to 380°C, or 310°C to 350°C.

[0074] In this specification, the melting point of liquid crystal polyester is measured in accordance with JIS K7121 using a differential scanning calorimeter DSC-60 Plus (manufactured by Shimadzu Corporation). Specifically, 10 mg of liquid crystal polyester is placed in a sample container and heated from room temperature to 350°C at a rate of 10°C / min, and held at 350°C for 10 minutes. Then, it is cooled to 50°C at a rate of 10°C / min and held at 50°C for 10 minutes. The position of the endothermic peak that appears when the temperature is then heated again at a rate of 10°C / min is defined as the melting point (Tm) of the liquid crystal polyester.

[0075] (Support layer) The support layer is a layer containing liquid crystal polyester.

[0076] The liquid crystal polyester content in the support layer may be, for example, 80% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, or 99% by mass or more, or 100% by mass, based on the total amount of the support layer.

[0077] The support layer may further contain other components besides liquid crystal polyester.

[0078] Other components include, for example, fibrous fillers, resins other than liquid crystal polyester, fillers other than fibrous fillers, flame retardants, conductivity imparters, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration damping agents, antibacterial agents, insecticides, deodorants, color inhibitors, heat stabilizers, antistatic agents, plasticizers, lubricants, dyes, foaming agents, antifoaming agents, viscosity modifiers, surfactants, and the like.

[0079] The fibrous filler may be an inorganic filler or an organic filler.

[0080] Examples of fibrous inorganic fillers include glass fibers, irregularly shaped cross-section glass fibers, carbon fibers, silica fibers, alumina fibers, ceramic fibers, metal fibers, silicon carbide fibers, and whiskers. Examples of fibrous organic fillers include polyester fibers, para-aramid fibers, and poly(p-phenylenebenzobisoxazole (PBO)) fibers.

[0081] Other fillers besides fibrous fillers include plate-shaped fillers, spherical fillers, and powder-shaped fillers.

[0082] Examples of plate-shaped fillers include talc, mica, glass flakes, and graphite. Plate-shaped fillers may be surface-treated or untreated. Examples of mica include natural mica such as muscovite, phlogopite, fluorphlogopite, and tetrasilicate mica, as well as artificially produced synthetic mica. Examples of spherical fillers include glass beads and glass balloons. Examples of powdered fillers include calcium carbonate, dolomite, clay, barium sulfate, titanium dioxide, carbon black, conductive carbon, and fine silica.

[0083] Other resins besides liquid crystal polyester include, for example, fluororesins, polyolefin resins, vinyl resins, polystyrene resins, polyamide resins, polyester resins, polysulfone resins, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether, and polyimide resins.

[0084] The content of other components in the support layer may be, for example, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less, or even 0% by mass, based on the total amount of the support layer.

[0085] The support layer may be, for example, an extruded article of a resin composition containing liquid crystal polyester.

[0086] An extruded article refers to a molded article obtained by extruding a resin composition. The extrusion method is not particularly limited and may be appropriately selected from known extrusion methods.

[0087] When the support layer is an extruded body, the coefficient of linear expansion of the support layer (extruded body) in the TD direction may be, for example, -5 or more, and may be 0 or more, 1 or more, 2 or more, 4 or more, 6 or more, or 8 or more. When the support layer is an extruded body, the coefficient of linear expansion of the support layer (extruded body) in the TD direction may be, for example, 15 or less, and may be 13 or less, or 10 or less. That is, when the support layer is an extruded body, the coefficient of linear expansion of the support layer (extruded body) in the TD direction may be, for example, -5 to 15, -5 to 13, -5 to 10, 0 to 15, 0 to 13, 0 to 10, 1 to 15, 1 to 13, 1 to 10, 2 to 15, 2 to 13, 2 to 10, 4 to 15, 4 to 13, 4 to 10, 6 to 15, 6 to 13, 6 to 10, 8 to 15, 8 to 13, or 8 to 10. Note that the unit of the coefficient of linear expansion is ×10 －５ (1 / K)

[0088] When the support layer is an extruded body, the linear expansion coefficient of the support layer (extruded body) in the MD direction may be, for example, -3 or more, -2 or more, -1 or more, or -0.5 or more. Alternatively, the linear expansion coefficient of the support layer (extruded body) in the MD direction may be, for example, 3 or less, 2 or less, 1 or less, or 0 or less. That is, when the support layer is an extruded body, the linear expansion coefficient of the support layer (extruded body) in the MD direction may be, for example, -3 to 3, -3 to 2, -3 to 1, -3 to 0, -2 to 3, -2 to 2, -2 to 1, -2 to 0, -1 to 3, -1 to 2, -1 to 1, -1 to 0, -0.5 to 3, -0.5 to 2, -0.5 to 1, or -0.5 to 0. The unit of the linear expansion coefficient is ×10⁻⁶. －５ (1 / K)

[0089] When the support layer is an extruded body, the absolute value of the difference between the linear expansion coefficient in the TD direction and the linear expansion coefficient in the MD direction of the support layer (extruded body) may be, for example, 0 or greater, 1 or greater, 4 or greater, or 8 or greater. A larger absolute value of the difference in linear expansion coefficients tends to result in better adhesion of the support layer to the semiconductor wafer. Furthermore, the absolute value of the difference between the linear expansion coefficient in the TD direction and the linear expansion coefficient in the MD direction of the support layer (extruded body) may be, for example, 15 or less, 13 or less, or 10 or less. A smaller absolute value of the difference in linear expansion coefficients tends to reduce twisting of the semiconductor wafer support sheet during polishing or grinding of the semiconductor wafer. That is, when the support layer is an extruded body, the absolute value of the difference between the linear expansion coefficient in the TD direction and the linear expansion coefficient in the MD direction of the support layer (extruded body) may be, for example, 0 to 15, 0 to 13, 0 to 10, 1 to 15, 1 to 13, 1 to 10, 4 to 15, 4 to 13, 4 to 10, 8 to 15, 8 to 13, or 8 to 10. The unit of the absolute value of the difference in linear expansion coefficients is ×10⁻⁶. －５ (1 / K)

[0090] In this specification, the coefficient of linear expansion of the support layer (extruded body) is expressed as the value measured using a thermomechanical analyzer (Rigaku Corporation, Thermo plus EVO2 series TMA8311) by the following method. A test specimen (1) with a length of 25 mm in the MD direction and a width of 4.5 mm in the TD direction is cut from the support layer (extruded body). The test specimen (1) is mounted on the thermomechanical analyzer with a chuck distance of 20 mm, and a tensile load of 25 mN is applied to both ends of the specimen. Next, the temperature is raised from room temperature to 250°C at a rate of 5°C / min, then cooled to 30°C at a rate of 20°C / min, and held at 30°C for 30 minutes. After that, the temperature is raised at a rate of 5°C / min, and the coefficient of linear expansion (CTE) in the MD direction (unit: ×10) is determined based on the change in length at 50°C and 100°C. －５ The coefficient of thermal expansion (CTE) in the TD direction is calculated (1 / K). Next, a measuring test piece (2) with a length of 25 mm in the TD direction and a width of 4.5 mm in the TD direction is cut from the support layer (extruded body). The same measurements as those for measuring test piece (1) are performed on measuring test piece (2) to determine the coefficient of thermal expansion (CTE) in the TD direction (unit: ×10). －５ Calculate (1 / K).

[0091] The thickness of the support layer may be, for example, 1 μm or more, and may be 3 μm or more, 5 μm or more, or 10 μm or more. A thicker support layer tends to result in better support of the semiconductor wafer by the semiconductor wafer support sheet. Alternatively, the thickness of the support layer may be, for example, 500 μm or less, and may be 300 μm or less, 200 μm or less, or 150 μm or less. A thinner support layer tends to reduce twisting of the semiconductor wafer support sheet during polishing or grinding of the semiconductor wafer. In other words, the thickness of the support layer may be, for example, 1 to 500 μm, 1 to 300 μm, 1 to 200 μm, 1 to 150 μm, 3 to 500 μm, 3 to 300 μm, 3 to 200 μm, 3 to 150 μm, 5 to 500 μm, 5 to 300 μm, 5 to 200 μm, 5 to 150 μm, 10 to 500 μm, 10 to 300 μm, 10 to 200 μm, or 10 to 150 μm.

[0092] A semiconductor wafer support sheet may have layers other than the support layer, or it may be substantially composed of only the support layer. Being substantially composed of only the support layer means that the proportion of the support layer in the semiconductor wafer support sheet is, for example, 95% or more by volume, preferably 97% or more, and more preferably 99% or more, based on the total volume of the semiconductor wafer support sheet. The proportion of the support layer in the semiconductor wafer support sheet may be 100% by volume.

[0093] When the semiconductor wafer support sheet is a multilayer sheet, it is preferable that at least one of the outermost layers is a support layer, and it is more preferable that the outermost layer on the side that is bonded to the semiconductor wafer is a support layer.

[0094] The semiconductor wafer support sheet may be directly bonded to the semiconductor wafer (so that the support layer and the semiconductor wafer are in contact), or it may be bonded to the semiconductor wafer via an adhesive layer.

[0095] The method of directly bonding the semiconductor wafer support sheet to the semiconductor wafer is not particularly limited, and may be, for example, fusion bonding.

[0096] The method of melt bonding is not particularly limited and may be appropriately selected from known methods. Melt bonding can be carried out by methods such as heating press or vacuum press.

[0097] In this embodiment, since the support layer contains liquid crystal polyester, the semiconductor wafer support sheet can be firmly bonded to the semiconductor wafer by melt bonding.

[0098] The method for bonding a semiconductor wafer support sheet and a semiconductor wafer via an adhesive layer is not particularly limited. Examples include a method of providing an adhesive layer on one side of a semiconductor wafer support sheet to create an adhesive-layered sheet, and then laminating the adhesive-layered sheet with a semiconductor wafer; or a method of providing an adhesive layer on a semiconductor wafer to create an adhesive-layered wafer, and then laminating the adhesive-layered wafer with a semiconductor wafer support sheet.

[0099] The adhesive layer may be a layer containing an adhesive. The adhesive is not particularly limited and may be appropriately selected from known adhesives used for bonding semiconductor wafers and backing sheets, for example. Examples of adhesives include adhesives containing adhesive resins such as acrylic resins, urethane resins, rubber resins, silicone resins, epoxy resins, polyvinyl ethers, and polycarbonates.

[0100] The thickness of the adhesive layer is not particularly limited and may be, for example, 0.01 μm or more, 0.1 μm or more, 1 μm or more, or 3 μm or more. Also, the thickness of the adhesive layer may be, for example, 20 μm or less, 10 μm or less, or 5 μm or less. That is, the thickness of the adhesive layer may be, for example, 0.01 to 20 μm, 0.01 to 10 μm, 0.01 to 5 μm, 0.1 to 20 μm, 0.1 to 10 μm, 0.1 to 5 μm, 1 to 20 μm, 1 to 10 μm, 1 to 5 μm, 3 to 20 μm, 3 to 10 μm, or 3 to 5 μm.

[0101] <Laminate> The laminate of this embodiment comprises a semiconductor wafer and a semiconductor wafer support sheet laminated on one side of the semiconductor wafer.

[0102] The semiconductor wafer support sheet may be directly laminated on one side of the semiconductor wafer, or it may be laminated via an adhesive layer. That is, the laminate of this embodiment may comprise a semiconductor wafer and a semiconductor wafer support sheet directly laminated on one side of the semiconductor wafer, or it may comprise a semiconductor wafer, an adhesive layer provided on one side of the semiconductor wafer, and a semiconductor wafer support sheet laminated on the adhesive layer.

[0103] The semiconductor wafer is not particularly limited and may be any known semiconductor wafer. For example, the semiconductor wafer may be a silicon wafer, a glass wafer, etc.

[0104] A semiconductor wafer may have circuits formed on the side on which the semiconductor wafer support sheet is laminated. Alternatively, a semiconductor wafer may have notches provided on the side on which the semiconductor wafer support sheet is laminated.

[0105] The side of the semiconductor wafer opposite the semiconductor wafer support sheet is the side that is ground. In the laminate of this embodiment, since the semiconductor wafer is supported by the semiconductor wafer support sheet, warping, cracking, etc. of the semiconductor wafer are suppressed during grinding.

[0106] Figure 1 shows one form of a laminate. The laminate 100 shown in Figure 1 comprises a semiconductor wafer 11 and a semiconductor wafer support sheet 12 laminated on the semiconductor wafer 11. In the laminate 100, the semiconductor wafer support sheet 12 is directly laminated on the surface S2 of the semiconductor wafer 11. Circuits may be formed on the surface S2 of the semiconductor wafer 11, or notches may be provided. The laminate 100 is suitable for grinding the surface S1 of the semiconductor wafer 11.

[0107] Figure 2 shows another form of the laminate. The laminate 200 shown in Figure 2 comprises a semiconductor wafer 21, a semiconductor wafer support sheet 22 laminated on the semiconductor wafer 21, and an adhesive layer 23 provided between the semiconductor wafer 21 and the semiconductor wafer support sheet 22 to bond them together. In the laminate 200, the semiconductor wafer support sheet 22 is laminated on the surface S4 of the semiconductor wafer 21 via the adhesive layer 23. Circuits may be formed on the surface S3 of the semiconductor wafer 21, or notches may be provided. The laminate 200 is suitably used for grinding the surface S3 of the semiconductor wafer 21.

[0108] In the laminate of this embodiment, the adhesion of the semiconductor wafer support sheet to the semiconductor wafer can be evaluated by its peel strength. The peel strength when peeling the semiconductor wafer support sheet from the semiconductor wafer may be, for example, 0.1 N / cm or more, 0.2 N / cm or more, 0.3 N / cm or more, or 0.5 N / cm or more. Higher peel strength tends to result in better support for the semiconductor wafer. Alternatively, the peel strength when peeling the semiconductor wafer support sheet from the semiconductor wafer may be, for example, 50 N / cm or less, 20 N / cm or less, 10 N / cm or less, or 5 N / cm or less. When the peel strength is within this range, it tends to be easier to peel the semiconductor wafer support sheet from the semiconductor wafer after polishing or grinding. In other words, the peel strength when peeling the semiconductor wafer support sheet from the semiconductor wafer may be, for example, 0.1 to 50 N / cm, 0.1 to 20 N / cm, 0.1 to 10 N / cm, 0.1 to 5 N / cm, 0.2 to 50 N / cm, 0.2 to 20 N / cm, 0.2 to 10 N / cm, 0.2 to 5 N / cm, 0.3 to 50 N / cm, 0.3 to 20 N / cm, 0.3 to 10 N / cm, 0.3 to 5 N / cm, 0.5 to 50 N / cm, 0.5 to 20 N / cm, 0.5 to 10 N / cm, or 0.5 to 5 N / cm.

[0109] In this specification, peel strength refers to the value measured in accordance with JIS K6854-1 using a universal testing machine Autograph AG-IS (manufactured by Shimadzu Corporation). Specifically, the semiconductor wafer support sheet is peeled in the MD direction perpendicular to the main surface of the semiconductor wafer at a speed of 1 mm / min, and the maximum peel force is determined as the peel strength.

[0110] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above.

[0111] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0112] (Example 1) (1-1) Production of liquid crystal polyester A-1 In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, 600.3 g (3.19 mol) of 2-hydroxy-6-naphthoic acid, 1078.7 g (7.81 mol) of p-hydroxybenzoic acid, 1235.3 g (12.1 mol) of acetic anhydride, and 0.168 g of 1-methylimidazole as a catalyst were added. After thoroughly purging the reactor with nitrogen gas, the temperature was raised to 140°C over 30 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 1 hour. Next, the temperature was raised from 140°C to 280°C over 4 hours while distilling off the distilled by-product acetic acid. After that, the reaction was considered complete when an increase in torque was observed, and the contents were removed and cooled to room temperature to obtain a solid. The obtained solid was pulverized in a pulverizer to obtain resin powder (particle size approximately 0.1 mm to approximately 1 mm). The obtained resin powder was heated under a nitrogen atmosphere from room temperature to 230°C over 1 hour, then heated from 230°C to 259°C over approximately 28 hours, and held at 259°C for 5 hours to allow the polymerization reaction to proceed in the solid phase, thereby obtaining liquid crystal polyester A.

[0113] (1-2) Pellet preparation Liquid crystal polyester A-1 was granulated using a twin-screw extruder (PCM30, manufactured by Ikegai Co., Ltd.) at a cylinder temperature of 300°C to obtain pellets of liquid crystal polyester A-1.

[0114] (1-3) Preparation of semiconductor wafer support sheet: The pellets were supplied to a single-screw extruder (screw diameter: 50 mm) and melted, then extruded into a film shape from a T-die (lip length: 300 mm, lip clearance: 1 mm, die temperature: 300 °C), and cooled to obtain a sheet (semiconductor wafer support sheet) with a width of 520 mm and a thickness of 100 μm.

[0115] (1-4) Preparation of Laminates Using a single-acting compression molding machine (NF-37 model, manufactured by Shinto Metal Industries Co., Ltd.) (hereinafter also referred to as a hot press machine), the sheet prepared in (1-3) above and a semiconductor wafer (manufactured by AS ONE Corporation, 3 inches in diameter, 380 ± 25 μm thick) were hot-pressed at a temperature of melting point + 10°C and a pressing time of 1 minute to obtain a laminate in which the sheet and semiconductor wafer were stacked.

[0116] (1-5) Evaluation The melting point of the liquid crystal polyester, the coefficient of linear expansion of the sheet, and the peel strength of the laminate were measured using the following methods. The results are shown in Table 1.

[0117] (i) Measurement of the melting point (Tm) of liquid crystal polyester The melting point of liquid crystal polyester was measured using a differential scanning calorimeter DSC-60 Plus (Shimadzu Corporation) in accordance with JIS K7121. Specifically, 10 mg of liquid crystal polyester was placed in a sample container and heated from room temperature to 350°C at a rate of 10°C / min, and held at 350°C for 10 minutes. Then, it was cooled to 50°C at a rate of 10°C / min and held at 50°C for 10 minutes. After that, the position of the endothermic peak that appeared when the temperature was heated again at a rate of 10°C / min was defined as the melting point (Tm) of the liquid crystal polyester.

[0118] (ii) Measurement of coefficient of linear thermal expansion (CTE) The coefficient of linear thermal expansion was measured by the following method using a thermomechanical analyzer (Thermo plus EVO2 series TMA8311, manufactured by Rigaku Corporation). From the sheet produced in (1-3) above, a test specimen (1) for measurement having a length of 25 mm in the MD direction and a width of 4.5 mm in the TD direction was cut out. The test specimen (1) for measurement was attached to the thermomechanical analyzer such that the distance between chucks was 20 mm, and a tensile load of 25 mN was applied to both ends of the test specimen. Next, after heating from room temperature to 250°C at a rate of 5°C / min, the temperature was cooled to 30°C at a rate of 20°C / min and held at 30°C for 30 minutes. Thereafter, the temperature was raised at a rate of 5°C / min, and based on the change in length at 50°C and the change in length at 100°C, the coefficient of linear thermal expansion (CTE) in the MD direction (unit: ×10 －５ / K) was calculated. Next, from the sheet produced in (1-3) above, a test specimen (2) for measurement having a length of 25 mm in the TD direction and a width of 4.5 mm in the TD direction was cut out. The same measurement as for test specimen (1) was performed on test specimen (2), and the coefficient of linear thermal expansion (CTE) in the TD direction (unit: ×10 －５ / K) was calculated.

[0119] (iii) Measurement of peel strength Peel strength was measured based on JIS K6854-1 using a universal testing machine Autograph AG-IS (manufactured by Shimadzu Corporation). Specifically, the semiconductor wafer support sheet was peeled off from the semiconductor wafer in the MD direction at a speed of 1 mm / min in a direction perpendicular to the main surface of the semiconductor wafer, and the maximum peel force was determined as the peel strength.

[0120] (Example 2) (2-1) Production of liquid crystal polyester B-1 In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, 1035.0 g (5.5 mol) of 6-hydroxy-2-naphthoic acid, 255.2 g of hydroquinone, 378.3 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid, 83.1 g (0.5 mol) of terephthalic acid, 1189.9 g of acetic anhydride, and 0.175 g of 1-methylimidazole as a catalyst were added and stirred at room temperature for 15 minutes, then the temperature was increased while stirring. When the internal temperature reached 140°C, the mixture was stirred for 1 hour while maintaining that temperature. Next, the temperature was increased from 140°C to 310°C over 4 hours and 40 minutes while distilling off the distilled by-product acetic acid and unreacted acetic anhydride. The temperature was maintained at 310°C for 1 hour and 30 minutes to obtain an aromatic polyester. The obtained aromatic polyester was cooled to room temperature and pulverized in a pulverizer to obtain aromatic polyester powder (particle size approximately 0.1 mm to 1 mm). The obtained powder was heated from 30°C to 225°C over 50 minutes, then from 225°C to 250°C over 1 hour and 40 minutes, and then from 250°C to 300°C over 8 hours and 20 minutes, followed by solid-phase polymerization at 300°C for 10 hours. After solid-phase polymerization, the powder was cooled to obtain liquid crystal polyester B-1.

[0121] (2-2) Production of liquid crystal polyester B-2 In a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer and reflux condenser, 1511.1 g (8.03 mol) of 6-hydroxy-2-naphthoic acid, 410.2 g (2.97 mol) of p-hydroxybenzoic acid, 1291.4 g (12.65 mol) of acetic anhydride, and 0.058 g of 1-methylimidazole as a catalyst were added and stirred at room temperature for 15 minutes, then the temperature was increased while stirring. When the internal temperature reached 140°C, the mixture was stirred for 1 hour while maintaining that temperature. Next, the temperature was increased from 140°C to 275°C over 2 hours and 50 minutes while distilling off the distilled by-product acetic acid and unreacted acetic anhydride. The temperature was maintained at 275°C for 3 hours to obtain aromatic polyester. The obtained aromatic polyester was cooled to room temperature and pulverized in a pulverizer to obtain aromatic polyester powder (particle size approximately 0.1 mm to approximately 1 mm). The obtained powder was heated from 30°C to 190°C over 1 hour and 10 minutes, then heated from 190°C to 260°C over 11 hours and 40 minutes, and held at 260°C for 10 hours to undergo solid-phase polymerization. After solid-phase polymerization, the powder was cooled to obtain liquid crystal polyester B-2.

[0122] (2-3) Pellet preparation Liquid crystal polyester B-1 and liquid crystal polyester B-2 were mixed in a mass ratio of 60:40, and granulated using a twin-screw extruder (Ikegai Co., Ltd., PCM30) at a cylinder temperature of 340°C to obtain pellets of the mixture of liquid crystal polyester B-1 and liquid crystal polyester B-2.

[0123] (2-4) Preparation of semiconductor wafer support sheet: The pellets were supplied to a single-screw extruder (screw diameter: 50 mm) and melted, then extruded into a film shape from a T-die (lip length: 300 mm, lip clearance: 1 mm, die temperature: 340 °C), and cooled to obtain a sheet (semiconductor wafer support sheet) with a width of 520 mm and a thickness of 100 μm.

[0124] (2-5) Preparation of the laminate A laminate was prepared in the same manner as in (1-4) of Example 1, except that the sheet prepared in (2-4) above was used.

[0125] (2-6) The melting point of the liquid crystal polyester, the coefficient of linear expansion of the sheet, and the peel strength of the laminate were measured in the same manner as in (1-5) of Evaluation Example 1. The results are shown in Table 1. The melting point of the liquid crystal polyester was measured for a mixture of liquid crystal polyester B-1 and liquid crystal polyester B-2 (60:40).

[0126] (Example 3) (3-1) Manufacturing of liquid crystal polyester B-1 Liquid crystal polyester B-1 was manufactured in the same manner as in (2-1) of Example 2.

[0127] (3-2) Preparation of pellets Liquid crystal polyester B-1 and titanium dioxide were mixed in a mass ratio of 99:1 and granulated using a twin-screw extruder (PCM30, manufactured by Ikegai Co., Ltd.) at a cylinder temperature of 340°C to obtain pellets of the liquid crystal polyester composition.

[0128] (3-3) Manufacturing of semiconductor wafer support sheets: Pellets were fed into the cylinder of a single-screw extruder with an inner cylinder diameter of 20 mm, kneaded under conditions of cylinder temperature of 320°C and screw rotation speed of 90 rpm, and a tubular film with a folded width of approximately 190 mm and a thickness of approximately 30 μm was manufactured by an inflation method in which the composition was extruded from an annular die with a die temperature of 300°C, an inner die diameter of 20 mm, and a die cap of 1.15 mm.

[0129] (3-4) Preparation of the laminate A laminate was prepared in the same manner as in (1-4) of Example 1, except that the sheet prepared in (3-3) above was used.

[0130] (3-5) The melting point of the liquid crystal polyester, the coefficient of linear expansion of the sheet, and the peel strength of the laminate were measured in the same manner as in (1-5) of Evaluation Example 1. The results are shown in Table 1. The melting point of the liquid crystal polyester was measured for a mixture of liquid crystal polyester B-1 and titanium oxide (99:1).

[0131]

[0132] 11, 21... Semiconductor wafers, 12, 22... Sheets for supporting semiconductor wafers, 23... Adhesive layer, 100, 200... Laminate.

Claims

1. A semiconductor wafer support sheet comprising a support layer containing liquid crystal polyester with a melting point of 250°C or higher.

2. The support layer is an extruded molded article of a resin composition containing liquid crystal polyester, and the coefficient of linear expansion of the extruded molded article in the TD direction is (×10 －５ (1 / K) and the coefficient of linear expansion in the MD direction (×10 －５ The absolute value of the difference between (1 / K) is 15 (×10 －５ A semiconductor wafer support sheet according to claim 1, wherein the (1 / K) ratio is less than or equal to (1 / K).

3. The semiconductor wafer support sheet according to claim 1, wherein the liquid crystal polyester contains a first monomer unit having a condensed aromatic ring and a second monomer unit having a benzene ring and not having a condensed aromatic ring.

4. A laminate comprising a semiconductor wafer and a semiconductor wafer support sheet according to any one of claims 1 to 3, laminated on one surface of the semiconductor wafer.

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