Substrate used in temporary fixing sheet for semiconductor processing and manufacturing method thereof, temporary fixing sheet for semiconductor processing, and manufacturing method of semiconductor element

Abstract

To provide a substrate used in a temporary fixing sheet for semiconductor processing, which has excellent conformability and backside grinding properties when applied to high-temperature processes.SOLUTION: A substrate according to the present invention used for a temporary fixing sheet for semiconductor processing includes a cushion layer, an adhesive layer provided on the cushion layer, and a barrier layer provided on the opposite side of the adhesive layer from the cushion layer, and the adhesive layer has a glass transition temperature of 15°C or lower, the adhesive layer has a shear storage modulus of 100 kPa or higher at 150°C, and the barrier layer has an oxygen permeability of 1000 ml / (m2 24h atm) or lower, measured in accordance with JIS K 7126-2 (isobaric method) at 25°C and RH 0%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a substrate used in a temporary fixing sheet for semiconductor processing and a method for manufacturing the same, a temporary fixing sheet for semiconductor processing, and a method for manufacturing a semiconductor element. [Background technology]

[0002] When semiconductor wafers are processed, temporary fixing sheets are applied to protect them from damage. For example, in the back grinding process when processing semiconductor wafers, temporary fixing sheets are applied to protect the patterned surface of the semiconductor wafer. Temporary fixing sheets are required to have adhesive properties for patterned surfaces with irregularities such as protruding electrodes (bumps), and to be able to conform to the irregularities of the patterned surface (step conformability) from the standpoint of reliable protection of the patterned surface. Furthermore, when applied to high-temperature processes, heat resistance is also required.

[0003] Patent Document 1 discloses an adhesive sheet for backgrinding that can improve the conformability of a base layer to protrusions on a semiconductor wafer. The base layer of the adhesive sheet for backgrinding is composed of a cushion layer and a barrier layer bonded together via an adhesive layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 249889 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present invention have conducted extensive research into the adhesive sheet for back grinding disclosed in Patent Document 1 and have found that when applied to high-temperature processes, the physical properties of the adhesive layer may fluctuate, resulting in insufficient conformability and back grindability.

[0006] The present invention has been made in view of the above circumstances, and provides a substrate to be used in a temporary fixing sheet for semiconductor processing, which has excellent conformability and backside grinding properties when applied to high-temperature processes. [Means for solving the problem]

[0007] According to the present invention, the following inventions are provided. [1] A substrate used in a temporary fixing sheet for semiconductor processing, comprising a cushion layer, an adhesive layer provided on the cushion layer, and a barrier layer provided on the opposite side of the cushion layer as viewed from the adhesive layer, wherein the glass transition temperature of the adhesive layer is 15°C or lower, the shear storage modulus of the adhesive layer at 150°C is 100 kPa or higher, and the oxygen permeability of the barrier layer measured based on JIS K7126-2 (isobaric method) at 25°C RH 0% is 1000 ml / (m 2 ·24h·atm) or less. [2] The substrate according to [1], wherein the adhesive strength between the cushion layer and the barrier layer measured by peeling the substrate at an angle of 180° from the barrier layer side in accordance with JIS Z0237 is 4.0 N / 20 mm or more. [3] A method for manufacturing a substrate according to [1] or [2], comprising an adhesive preparation step, an adhesive application step, and a substrate formation step, in which the adhesive preparation step comprises mixing an acrylic resin having an epoxy group with a multifunctional epoxy resin to prepare an adhesive, the adhesive application step comprises applying the adhesive onto the barrier layer, and the substrate formation step comprises bonding the cushion layer onto the adhesive applied onto the barrier layer to form the substrate. [4] A method for producing a substrate according to [3], wherein the acrylic resin further has a hydroxy group. [5] A method for producing a substrate according to [3] or [4], wherein the acrylic resin is a copolymer obtained by copolymerizing raw material monomers including butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate, and the acrylic resin is a copolymer obtained by copolymerizing 75 to 85 parts by mass of butyl acrylate with 100 parts by mass of the total of the raw material monomers. [6] A method for producing a substrate according to any one of [3] to [5], wherein the polyfunctional epoxy resin is a phenol novolac type epoxy resin. [7] A method for producing a substrate according to any one of [3] to [6], wherein a polyfunctional amine compound is further added in the adhesive preparation step. [8] The method for producing a substrate according to [7], wherein the polyfunctional amine compound is a polyalkylamine. [9] A temporary fixing sheet for semiconductor processing, comprising the substrate according to [1] or [2] and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is provided on the opposite side of the cushion layer from the adhesive layer.

[10] A method for manufacturing a semiconductor element using a temporary fixing sheet for semiconductor processing that uses the substrate described in [1] or [2], the method comprising a frame attaching step, a wafer attaching step, a heating step, and a grinding step, in which the frame attaching step attaches the temporary fixing sheet to a ring frame, the wafer attaching step attaches the temporary fixing sheet under reduced pressure to a first surface of a semiconductor wafer that has a convex portion, the heating step heats the substrate, and the grinding step grinds a second surface of the semiconductor wafer that is opposite to the first surface.

[11]

[10] The method for manufacturing a semiconductor element according to the present invention further comprises a cutting step and a resin curing step, in which the temporary fixing sheet is cut along the outer periphery of the semiconductor wafer in the cutting step, and in which the resin curing step brings the substrate into contact with a curable resin after the wafer laminating step, and hardens the curable resin in that state.

[0008] After extensive research, the inventors discovered that the above problem can be solved by setting the glass transition point of the adhesive layer below a predetermined value and setting the shear storage modulus of the adhesive layer at 150°C above a predetermined value, thereby completing the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a temporary fixing sheet 10 including a substrate 1 according to one embodiment of the present invention. [Figure 2] 2A to 2D are cross-sectional views showing a method for manufacturing a semiconductor element using the temporary fixing sheet 10 according to one embodiment of the present invention. [Figure 3] 3A and 3B are cross-sectional views showing a method for manufacturing a semiconductor element using the temporary fixing sheet 10 according to one embodiment of the present invention. [Figure 4] 4A to 4E are cross-sectional views showing a method for manufacturing a semiconductor element using the temporary fixing sheet 10 according to one embodiment of the present invention.

[0010] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0011] 1.Temporary fixing sheet A temporary fixing sheet 10 according to one embodiment of the present invention will be described below with reference to Figs. 1 to 4E. The temporary fixing sheet 10 according to one embodiment of the present invention comprises a base material 1 and a pressure-sensitive adhesive layer 2 provided on the base material 1. This temporary fixing sheet 10 is used when grinding the back surface 4b of a semiconductor wafer 4 having protrusions 5. Each component will be described below.

[0012] 1-1. Base material 1 As shown in Fig. 1, the substrate 1 includes a cushion layer 1a, an adhesive layer 1b, and a barrier layer 1c. The barrier layer 1c is preferably provided on the opposite side of the cushion layer 1a from the pressure-sensitive adhesive layer 2. The barrier layer 1c is preferably attached to the cushion layer 1a via the adhesive layer 1b. To improve the adhesion between the cushion layer 1a and the pressure-sensitive adhesive layer 2, a surface treatment layer 1d (not shown) may be provided between the cushion layer 1a and the pressure-sensitive adhesive layer 2, if necessary.

[0013] The overall thickness of the substrate 1 is preferably 50 to 400 μm, more preferably 70 to 300 μm, and even more preferably 90 to 200 μm. Specific examples of this thickness include 50, 100, 150, 200, 250, 300, 350, and 400 μm, and may be within a range between any two of the values ​​exemplified here.

[0014] <Cushion layer 1a> The cushion layer 1a is a layer for protecting the protrusions 5 of the semiconductor wafer 4. The cushion layer 1a is preferably made of a thermoplastic resin. The composition of the thermoplastic resin is not particularly limited, but examples thereof include ionomer resins in which the carboxyl groups of simple and / or complex materials such as ethylene-methacrylic acid-acrylic acid ester terpolymers, ethylene-methacrylic acid copolymers, and ethylene-acrylic acid copolymers are crosslinked with metal ions such as sodium ions, lithium ions, and magnesium ions; soft polyolefin resins in which polyolefin resins such as polypropylene and polyethylene are blended with elastomers such as styrene-butadiene copolymer rubber, styrene-butadiene-styrene block copolymer rubber, styrene-isoprene-styrene block copolymer rubber, and ethylene-propylene rubber; low-density polyethylene, ethylene-propylene block copolymers, ethylene-propylene random copolymers, ethylene-vinyl acetate copolymers, ethylene-methacrylic acid copolymers, ethylene-1-octene copolymers, and polybutene. The thermoplastic resin is preferably a PO-based resin based on polyolefin (PO), and more preferably an ionomer resin or a soft polyolefin resin obtained by blending an elastomer into a polyolefin resin.

[0015] The proportion Ra (mass%) of (meth)acrylic monomer units in the resin constituting the cushion layer 1a is preferably lower than the proportion Rd (mass%) of (meth)acrylic monomer units in the acrylic resin constituting the surface-treated layer 1d. In this case, the adhesion between the pressure-sensitive adhesive layer 2 composed of the acrylic resin composition and the surface-treated layer 1d is higher than the adhesion between the pressure-sensitive adhesive layer 2 and the cushion layer 1a, making the provision of the surface-treated layer 1d technically significant. The value of (Rd-Ra) is, for example, 10 to 100 mass%, preferably 30 to 100 mass%. Specific examples of this value include 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mass%, and may be within a range between any two of the values ​​exemplified here.

[0016] The tensile storage modulus E'a of the cushion layer 1a at 180°C is preferably lower than the tensile storage modulus E'd of the surface treatment layer 1b at 180°C. If the tensile storage modulus E'a of the cushion layer 1a under high-temperature conditions is low, the cushion layer 1a may be excessively softened during heating, resulting in strong adhesion to the wafer and difficulty in peeling. The provision of the surface treatment layer 1d prevents such problems. Therefore, the provision of the surface treatment layer 1d is technically significant when the tensile storage modulus E'a is lower than the tensile storage modulus E'd. If the tensile storage modulus E'a cannot be measured due to melting of the cushion layer 1a, the tensile storage modulus E'a is set to 0 for convenience.

[0017] The weight average molecular weight (Mw) of the thermoplastic resin is preferably from 10,000 to 1,000,000, and more preferably from 50,000 to 500,000. The weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0018] The softening temperature (JIS K7206) of the thermoplastic resin is preferably 45 to 200° C., more preferably 55 to 150° C. Specific examples of the softening temperature include 45, 50, 55, 60, 65, 70, 75, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200° C., and may be within a range between any two of the values ​​exemplified here.

[0019] The melting point (JIS K7121) of the thermoplastic resin is preferably 60 to 200° C., more preferably 80 to 150° C. Specific examples of the melting point include 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200° C., and may be within a range between any two of the values ​​exemplified here.

[0020] The melt flow rate (MFR) (JIS K7210, 125°C / 10.0 kg load) of the thermoplastic resin is preferably 0.2 to 30 g / 10 min, more preferably 0.3 to 20 g / 10 min.

[0021] When the thermoplastic resin has the above physical properties, the cushion layer 1a is softened appropriately as the substrate 1 is heated, so that the protrusions 5 can be easily embedded in the substrate 1.

[0022] The thickness of the cushion layer 1a is preferably 50 to 400 μm, more preferably 60 to 300 μm, and even more preferably 70 to 200 μm. Specific examples of this thickness include 50, 100, 150, 200, 250, 300, 350, and 400 μm, and may be within a range between any two of the values ​​exemplified here.

[0023] <Adhesive layer 1b> The adhesive layer 1b is a layer for adhering the cushion layer 1a and the barrier layer 1c. As will be described later, the adhesive layer 1b can be formed by applying an adhesive made by mixing an acrylic resin and an epoxy resin onto the barrier layer 1c and / or the cushion layer 1a.

[0024] In this specification, acrylic resin means a resin containing 50% by mass or more of (meth)acrylic monomer units. (Meth)acrylic monomer means a compound having a (meth)acryloyl group. The (meth)acrylic monomer is preferably monofunctional. As will be described later, acrylic resins can also be used for purposes other than the preparation of adhesives. Acrylic resins will be described below.

[0025] Examples of (meth)acrylic monomers include (meth)acrylic acid and / or (meth)acrylic acid esters, such as alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, and (meth)acrylates having a cyclic ether skeleton.

[0026] The alkyl(meth)acrylate is preferably a (meth)acrylate represented by the following general formula (A).

[0027] (A)ZOR (In the formula, Z represents a (meth)acryloyl group, and R represents an alkyl group having 1 to 10 carbon atoms.)

[0028] Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, and dodecyl (meth)acrylate.

[0029] Hydroxyalkyl (meth)acrylates include 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and glycerol mono(meth)acrylate.

[0030] Examples of (meth)acrylates having a cyclic ether skeleton include glycidyl (meth)acrylate, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate, (2-methyl-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, cyclic trimethylolpropane formal (meth)acrylate, γ-butyrolactone (meth)acrylate, dioxolane (meth)acrylate, dioxane glycol di(meth)acrylate, and oxetane (meth)acrylate, and one or more of these can be used. The cyclic ether skeleton preferably has 2 to 5 carbon atoms. Among (meth)acrylates having a cyclic ether skeleton, glycidyl (meth)acrylate is preferred.

[0031] The acrylic resin may contain only (meth)acrylic monomer units, or may contain other monomer units in addition to (meth)acrylic monomer units, such as olefins (ethylene, propylene, etc.), aliphatic vinyls (vinyl acetate, etc.), and aromatic vinyls (styrene, etc.).

[0032] The proportion of the (meth)acrylic monomer unit in the acrylic resin is, for example, 50 to 100 mass %, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 mass %, and may be within a range between any two of the numerical values ​​exemplified here.

[0033] Acrylic resins can be obtained by polymerizing raw material monomers including the above monomers. Details of the acrylic resins used in adhesives will be explained in "2. Method for manufacturing substrates."

[0034] In this specification, the acrylic resin composition refers to a composition containing the above-mentioned acrylic resin, and can constitute the adhesive layer 1b, the surface treatment layer 1d, and the pressure-sensitive adhesive layer 2. The acrylic resin composition preferably contains a crosslinking agent. The acrylic resin is crosslinked by the reaction between the acrylic resin and the crosslinking agent. Examples of the crosslinking agent include acrylate crosslinking agents, isocyanate crosslinking agents, epoxy crosslinking agents, and amine compounds. These may be used alone or in combination of two or more. Details of the acrylic resin composition (adhesive) that constitutes the adhesive layer 1b will be described in the <Adhesive Preparation Step> section of "2. Substrate Manufacturing Method."

[0035] Examples of acrylate crosslinking agents include compounds having multiple (meth)acryloyl groups, and specific examples include 1,9-nonanediol diacrylate, 1,6-hexanediol diacrylate, triethylene glycol diacrylate, polytetramethylene glycol diacrylate, neopentyl glycol diacrylate, and 3-methyl-1,5 pentanediol diacrylate.

[0036] Examples of the isocyanate crosslinking agent include polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate, as well as derivatives thereof (adducts, biurets, isocyanurates).

[0037] Examples of epoxy crosslinking agents include epoxy resins having multiple epoxy groups. Epoxy resins can be classified based on the molecular structure of the prepolymer, for example, into glycidyl ether, glycidyl ester, glycidyl amine, and alicyclic (olefin oxidation) types. Examples of glycidyl ether epoxy resins include bifunctional repeating structure types such as bisphenol A epoxy resins and bisphenol F epoxy resins, multifunctional repeating structure types such as cresol novolac epoxy resins and phenol novolac epoxy resins, and multifunctional monomer types of monomers having multiple epoxy groups. In this specification, "multifunctional" means that three or more functional groups are present in the molecule.

[0038] Examples of amine compounds include amine crosslinking agents such as aliphatic polyamines and aromatic polyamines, and polyamide crosslinking agents. Examples of aliphatic polyamines include linear aliphatic polyamines such as diethylenetriamine, triethylenetriamine, and tetraethylenetriamine, and cyclic aliphatic polyamines such as N-aminoethylpiperazine, menthenediamine, and isophoronediamine. Examples of aromatic polyamines include metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Polyamide crosslinking agents are polyfunctional compounds having multiple amino groups and at least one amide group in the molecule, and can be obtained, for example, by condensing a dimer acid such as linoleic acid or a fatty acid with the above-mentioned polyamines.

[0039] In the acrylic resin composition, the amount of crosslinking agent blended relative to 100 parts by mass of the acrylic resin is, for example, 0.5 to 30 parts by mass, preferably 1 to 25 parts by mass, and more preferably 2 to 20 parts by mass. Specific examples of this blending amount include 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, and 30 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0040] The acrylic resin can be crosslinked by, for example, light irradiation or heat. The acrylic resin may be one that reacts with a crosslinking agent at room temperature.

[0041] In the case of crosslinking by light irradiation, the acrylic resin composition preferably contains a photopolymerization initiator. Specific examples of the photopolymerization initiator include, but are not limited to, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators, with acetophenone-based photopolymerization initiators being preferred.

[0042] Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, and methoxyacetophenone.

[0043] The Mw of the acrylic resin before crosslinking is preferably 300,000 to 2,000,000, and more preferably 450,000 to 800,000. If the Mw is too low, heat resistance may be insufficient, while if the Mw is too high, the viscosity may be too high, making coating difficult and reducing productivity. Specific examples of Mw include 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 900,000, 1,000,000, 1,100,000, 1,200,000, 1,300,000, 1,400,000, 1,500,000, 1,600,000, 1,700,000, 1,800,000, 1,900,000, and 2,000,000, and may fall within a range between any two of the values ​​exemplified here.

[0044] The adhesive layer 1b can be formed by crosslinking an adhesive prepared by the method described below in <Adhesive Preparation Step> of "2. Method for Producing Substrate". The adhesive is one of the above acrylic resins and may be prepared so as to be crosslinkable at room temperature. The glass transition temperature (Tg) of the adhesive before crosslinking is preferably -15 to 40°C, more preferably -10 to 30°C. Specific examples of this Tg include -15, -10, -5, 0, 5, 10, 15, 20, 25, 30, 35, and 40°C, and may be within a range between any two of the values ​​exemplified here. The Tg of the adhesive layer 1b obtained by crosslinking the adhesive is preferably -10 to 20°C, more preferably -5 to 15°C. Specific examples of this Tg include -10, -5, 0, 5, 10, 15, and 20°C, and may be within a range between any two of the values ​​exemplified here. By setting the Tg of the adhesive before crosslinking and the adhesive layer 1b obtained by crosslinking the adhesive within the above range, the backside grindability when the temporary fixing sheet 10 is used becomes excellent.

[0045] In this specification, Tg is measured as follows: Differential scanning calorimetry (DSC) is performed according to JIS K 7121: 1987. Tg is defined as the intersection of the tangent to the baseline of the DSC curve and the tangent to the steep drop in the endothermic region due to glass transition.

[0046] <Barrier layer 1c> The barrier layer 1c is a layer for reducing the oxygen permeability of the base material 1. If the base material 1 is easily permeable to air, outside air may enter the sealed space 2b through the base material 1, making it difficult to reduce the pressure inside the sealed space 2b. As a result, a problem may arise in which the base material 1 is less likely to conform to the protrusions 5.

[0047] The barrier layer 1c is a layer with low oxygen permeability. When the oxygen permeability is low, the air permeability is usually also low, so by providing the barrier layer 1c, it is possible to prevent outside air from entering the sealed space 2b through the base material 1, thereby achieving the effect of making it easier for the base material 1 to conform to the protrusions 5.

[0048] The barrier layer 1c has an oxygen permeability of 1000 ml / (m2) measured based on JIS K 7126-2 (constant pressure method) at 25°C and 0% RH of the substrate 1. 2 In order to set the oxygen permeability of the substrate 1 in this range, it is preferable that the oxygen permeability of the barrier layer 1c alone under the same conditions is 1000 ml / (m2·24h·atm) or less. In this case, the above-mentioned effect is easily exhibited. The oxygen permeability of the substrate 1 or the barrier layer 1c is, for example, 0 to 1000 ml / (m 2 ·24h·atm) and 0~500ml / (m 2 24h atm), and specifically, for example, 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 ml / (m 2 ·24h·atm) and may be within a range between any two of the values ​​given here as examples.

[0049] Under the above conditions, the oxygen permeability of the barrier layer 1c is preferably lower than that of the cushion layer 1a. The value of (oxygen permeability of the cushion layer 1a - oxygen permeability of the barrier layer 1c) is 100 ml / (m 2 This value is preferably 100 to 3000 ml / (m 2 ·24h·atm), and specifically, for example, 100, 500, 1000, 1500, 2000, 2500, 3000 ml / (m 2 ·24h·atm) and may be within a range between any two of the values ​​given here as examples.

[0050] The barrier layer 1c can be formed of any material that can achieve the above oxygen permeability, and polyester (for example, polyethylene terephthalate), polyimide, and polyamide are preferred from the viewpoint of ease of reducing oxygen permeability.

[0051] The thickness of the barrier layer 1c is, for example, 5 to 50 μm, and preferably 10 to 30 μm. If the barrier layer 1c is too thin, the oxygen permeability of the substrate 1 may not be sufficiently low. If the barrier layer 1c is too thick, the conformability to the protrusions 5 of the substrate 1 may be poor. Specific examples of this thickness are 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0052] <Surface treatment layer 1d> The surface treatment layer 1d is a layer that can be optionally provided on the cushion layer 1a. The surface treatment layer 1d is formed of an acrylic resin composition containing an acrylic resin, and is crosslinked by light irradiation or heating. If the pressure-sensitive adhesive layer 2 is formed directly on the cushion layer 1a, peeling of the pressure-sensitive adhesive layer 2 may occur if the adhesion between the cushion layer 1a and the pressure-sensitive adhesive layer 2 is poor. However, by forming the surface treatment layer 1d on the cushion layer 1a and then forming the pressure-sensitive adhesive layer 2 from an acrylic resin composition, peeling of the pressure-sensitive adhesive layer 2 can be suppressed.

[0053] The definitions of the acrylic resin and acrylic resin composition used to form the surface-treated layer 1d are as explained above in the description of the adhesive layer 1b. The composition of the acrylic resin used to form the surface-treated layer 1d may be the same as or different from the acrylic resin used to form the adhesive layer 1b. An acrylate-based crosslinking agent or an isocyanate-based crosslinking agent is preferably used as the crosslinking agent in the acrylic resin composition forming the surface-treated layer 1d. The glass transition temperature (Tg) of the acrylic resin in the acrylic resin composition forming the surface-treated layer 1d before crosslinking is preferably −15 to 40°C, more preferably −10 to 30°C. Specifically, the Tg may be, for example, −15, −10, −5, 0, 5, 10, 15, 20, 25, 30, 35, or 40°C, and may be within a range between any two of the values ​​exemplified here. Furthermore, the Tg after crosslinking of the acrylic resin in the acrylic resin composition constituting the surface treatment layer 1d is preferably 10 to 80° C., more preferably 20 to 70° C. Specific examples of this Tg include 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80° C., and may be within a range between any two of the values ​​exemplified here.

[0054] The surface treatment layer 1d has a tensile storage modulus of 1.0 × 10 at 180 °C. 4 Pa~1.0×10 8 It is preferable that the tensile storage modulus is 0.05 Pa. If this tensile storage modulus is too low, when the temporary fixing sheet 10 is heated when attaching a wafer to the temporary fixing sheet 10, the surface treatment layer 1d becomes too soft, and as a result, the surface treatment layer 1d breaks as the cushion layer 1a melts, and residues of the surface treatment layer 1d may remain on the wafer or the peelability may be impaired. If this tensile storage modulus is too high, the surface treatment layer 1d may be too hard, and the ability to conform to the protrusions 5 of the base material 1 may be impaired.

[0055] Specifically, the tensile storage modulus is, for example, 1.0×10 4 Pa, 1.0 × 10 5 Pa, 1.0 × 10 6 Pa, 1.0 × 107 Pa, 1.0 × 10 8 Pa and may be in the range between any two of the values ​​exemplified here.

[0056] The thickness of the surface treatment layer 1d is, for example, 0.1 to 10 μm, preferably 0.5 to 5 μm, and more preferably 1 to 4 μm. When the surface treatment layer 1d has such a thickness, the effect of providing the surface treatment layer 1d is likely to be properly exhibited. Specific examples of this thickness include 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0 μm, and may be within a range between any two of the numerical values ​​exemplified here.

[0057] 2. Adhesive layer 2 The pressure-sensitive adhesive layer 2 is a layer for adhering the temporary fixing sheet 10 to the semiconductor wafer 4, and is formed of a pressure-sensitive adhesive. The shape of the pressure-sensitive adhesive layer 2 is not particularly limited as long as it is a shape that allows the temporary fixing sheet 10 to be adhered to the semiconductor wafer 4. For example, the pressure-sensitive adhesive layer 2 can be configured to cover the entire surface of the semiconductor wafer 4.

[0058] The adhesive layer 2 may also be configured to have openings with a diameter smaller than the diameter of the semiconductor wafer 4. The openings are areas where no adhesive is provided and are smaller than the diameter of the semiconductor wafer 4. The ratio of the diameter of the openings to the diameter of the semiconductor wafer 4 is preferably 0.950 to 0.995, and more preferably 0.960 to 0.990. When the adhesive layer 2 has openings, the outer periphery 4a of the semiconductor wafer 4 is attached to the adhesive layer 2 so that the protrusions 5 of the semiconductor wafer 4 are positioned within the openings. Therefore, the protrusions 5 do not come into contact with the adhesive, preventing adhesive residue on the protrusions 5.

[0059] The thickness of the adhesive layer 2 is usually 1 to 200 μm, preferably 2 to 170 μm, and more preferably 5 to 150 μm. If the thickness of the adhesive layer 2 is less than 1 μm, it is not possible to ensure sufficient adhesive strength to the surface of the ring frame 3 or the surface of the semiconductor wafer 4. On the other hand, if the thickness of the adhesive layer 2 is greater than 200 μm, adhesive residue may be left when peeled off from the surface of the ring frame 3 or the surface of the semiconductor wafer 4, and economic efficiency may be reduced.

[0060] The pressure-sensitive adhesive layer 2 is preferably formed of an acrylic resin composition containing an acrylic resin. The composition of the acrylic resin in the pressure-sensitive adhesive layer 2 may be the same as or different from the composition of the acrylic resin in the adhesive layer 1b or the surface treatment layer 1d.

[0061] The proportion of (meth)acrylic monomer units contained in the acrylic resin constituting the pressure-sensitive adhesive layer 2 is, for example, 50 to 100 mass%, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 mass%, and may be within a range between any two of the numerical values ​​exemplified here.

[0062] Examples of (meth)acrylic monomers include butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic monomers and functional group-containing monomers include benzyl (meth)acrylate, dimethylacrylamide, diethylacrylamide, acryloylmorpholine, isobornyl acrylate, etc., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, etc., which have a hydroxyl group; (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, acrylamido-N-glycolic acid, cinnamic acid, etc., which have a carboxyl group; allyl glycidyl ether and (meth)acrylic acid glycidyl ether, etc., which have an epoxy group.

[0063] It is preferable to blend a crosslinking agent into the acrylic resin composition that constitutes the pressure-sensitive adhesive layer 2. Examples of crosslinking agents include polyfunctional isocyanate crosslinking agents and polyfunctional epoxy crosslinking agents. When the crosslinking agent reacts with the functional group, a crosslinked structure is formed using the functional group as the base point, thereby increasing the cohesive strength of the pressure-sensitive adhesive and reducing adhesive residue. Furthermore, (meth)acrylates in which one or more (meth)acryloyl groups are added to the end or side chain of an oligomer / polymer, such as 1,2-polybutadiene-terminated urethane (meth)acrylate, its hydrogenated derivatives, 1,4-polybutadiene-terminated urethane (meth)acrylate, polyisoprene-terminated (meth)acrylate, polyester-based urethane (meth)acrylate, polyether-based urethane (meth)acrylate, polyester (meth)acrylate, or bis-A type epoxy (meth)acrylate, may also be used.

[0064] In the acrylic resin composition constituting the pressure-sensitive adhesive layer 2, the amount of crosslinking agent blended per 100 parts by mass of the acrylic resin is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 1 to 6 parts by mass. Specific examples of this amount are 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, and 10.0 parts by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0065] The acrylic resin in the acrylic resin composition constituting the pressure-sensitive adhesive layer 2 preferably has a glass transition temperature (Tg) after crosslinking of −30 to 5° C., more preferably −25 to −5° C. Specific examples of Tg include −30, −25, −20, −15, −10, −5, 0, and 5° C., and may be within a range between any two of the values ​​exemplified here.

[0066] The adhesive layer 2 can be formed by coating the adhesive onto the substrate 1 using a coating method such as a common comma coating, gravure coating, roll coating, or screen coating, or by coating the adhesive onto a release film and then transferring it to the substrate 1.

[0067] The adhesive strength between the adhesive layer 2 and the semiconductor wafer, measured in accordance with JIS Z0237 at 23°C after heating the semiconductor wafer to which the adhesive layer 2 is attached for 1 minute in an atmosphere at 100°C and cooling to room temperature, is preferably 6 to 50 N / 200 mm, and more preferably 10 to 30 N / 200 mm. The adhesive strength under the above measurement conditions before heating is preferably 6 N / 200 mm or more, for example, 6 to 50 N / 200 mm. Specific examples of such adhesive strengths include 6, 10, 15, 20, 25, 30, 35, 40, 45, and 50 N / 200 mm, and may be within a range between any two of the values ​​exemplified here.

[0068] <Semiconductor wafer 4> The semiconductor wafer 4 has a protrusion 5. The protrusion 5 is any structure that protrudes out of the plane of the semiconductor wafer 4. Examples of the protrusion 5 include a protruding electrode and a protrusion of a circuit having irregularities.

[0069] Examples of the semiconductor wafer 4 include not only silicon wafers but also germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. The diameter of the semiconductor wafer 4 is preferably 1 to 16 inches, and more preferably 4 to 12 inches. The thickness of the semiconductor wafer 4 is not particularly limited, but is preferably 500 to 800 μm, and more preferably 520 to 775 μm.

[0070] The height of the protrusions 5 is preferably 10 to 500 μm, and more preferably 70 to 300 μm. Specific examples of the height include 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, and 500 μm, and may be within a range between any two of the values ​​exemplified here.

[0071] The semiconductor wafer 4 preferably has an outer periphery 4a that is not provided with the protrusions 5. The width of the outer periphery 4a is preferably 1.0 to 3.0 mm, and more preferably 1.5 to 2.5 mm.

[0072] Final products using the semiconductor wafer 4 having the protrusions 5 include electronic components for logic, memory, sensors, power supplies, and the like.

[0073] 2. Manufacturing method of substrate The method for manufacturing the substrate 1 used in the temporary fixing sheet 10 includes an adhesive preparation step, an adhesive application step, and a substrate formation step. Each step will be described below.

[0074] <Adhesive manufacturing process> The adhesive preparation step is a step of preparing an adhesive, which is a type of acrylic resin composition, by mixing an acrylic resin for adhesives having epoxy groups with a crosslinking agent. The definitions of acrylic resin and acrylic resin composition are as explained in <Adhesive layer 1b> in "1. Temporary fixing sheet" above. The acrylic resin for adhesives has at least an epoxy group and preferably also has a hydroxyl group.

[0075] Acrylic resins for adhesives can be obtained by copolymerizing raw material monomers including, for example, alkyl (meth)acrylate, hydroxyalkyl (meth)acrylate, and (meth)acrylate having a cyclic ether skeleton. As the alkyl (meth)acrylate, butyl acrylate or ethyl acrylate is preferably used. In one embodiment, the raw material monomers preferably include butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate.

[0076] The alkyl (meth)acrylate is the main component of the acrylic resin for the adhesive, and its amount is preferably 75 to 85 parts by mass, more preferably 75 to 80 parts by mass, per 100 parts by mass of the total raw material monomers.Specific examples include 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, and 85 parts by mass, and may be within a range between any two of the values ​​exemplified here.By keeping the amount of alkyl (meth)acrylate within this range, the Tg of the adhesive layer 1b obtained by crosslinking the adhesive (acrylic resin composition) containing the acrylic resin for the adhesive can be lowered, and the backside grindability when using the temporary fixing sheet 10 can be improved.

[0077] The adhesive is a type of acrylic resin composition and contains a crosslinking agent. As the crosslinking agent, an epoxy-based crosslinking agent is preferably used, a multifunctional epoxy resin is more preferably used, and a multifunctional phenol novolac epoxy resin is even more preferably used. The acrylic resin having epoxy groups reacts with the epoxy-based crosslinking agent to crosslink the adhesive layer 1b, increasing the shear storage modulus at 150°C. This suppresses fluctuations in the physical properties of the temporary fixing sheet 10 at high temperatures, resulting in excellent conformability of the temporary fixing sheet 10.

[0078] As the polyfunctional phenol novolac epoxy resin, for example, a compound represented by the following chemical formula (1) or chemical formula (2) can be preferably used, but is not limited thereto. [ka] (In the formula, l represents an integer of 1 to 20, and m represents an integer of 1 to 20.) [ka] (In the formula, n represents an integer of 1 to 4.)

[0079] The integer l in chemical formula (1) is 1 to 20, preferably 5 to 15. Specific examples of the integer l include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20, and may be within a range between any two of the numerical values ​​exemplified here. The integer m in chemical formula (1) is 1 to 20, preferably 5 to 15. Specific examples of the integer l include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20, and may be within a range between any two of the numerical values ​​exemplified here. Furthermore, the integer n in chemical formula (2) is 1 to 4, preferably 2 to 3. Specifically, the integer n is, for example, 1, 2, 3, or 4, and may be within a range between any two of the numerical values ​​exemplified here.

[0080] The epoxy equivalent of the compound represented by chemical formula (1) is preferably 400 to 700, more preferably 500 to 600. Specific examples of the epoxy equivalent include 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, and 700, and may be within a range between any two of the values ​​exemplified here. The epoxy equivalent of the compound represented by chemical formula (2) is preferably 150 to 200, more preferably 160 to 170. Specifically, the epoxy equivalent weight is, for example, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200, and may be within a range between any two of the values ​​exemplified here. By adjusting the epoxy equivalent weight of these compounds to fall within the above range, an adhesive with excellent heat resistance can be produced.

[0081] In addition, in the adhesive preparation process, an amine compound may be used in combination with an epoxy crosslinking agent. In this case, the amine compound is preferably a polyamide crosslinking agent, and more preferably a polyalkylamine. Examples of polyalkylamines include modified polyamideamines, which are condensates of fatty acids such as linoleic acid and polyethylene polyamines such as diethylenetriamine and triethylenetetramine. The amine value of the amine compound is preferably 300 to 350, more preferably 320 to 340, and specifically, for example, 300, 310, 320, 330, 340, or 350, and may be within a range between any two of the values ​​exemplified here. By setting the amine value within the above range, an adhesive with excellent heat resistance can be prepared.

[0082] <Adhesive application process> The adhesive application step is a step of applying the adhesive prepared in the adhesive preparation step onto the barrier layer 1c and / or cushion layer 1a. It is preferable to apply the adhesive onto the barrier layer 1c. After applying the adhesive, it is more preferable to dry the adhesive at a drying temperature of 80°C to 110°C for a drying time of 0.5 to 2 minutes. The drying temperature is, for example, 80, 85, 90, 95, 100, 105, or 110°C, and may be within a range between any two of the values ​​exemplified here. The drying time is, for example, 0.5, 1, 1.5, or 2 minutes, and may be within a range between any two of the values ​​exemplified here. By drying the adhesive at a temperature and for a time within the above ranges, an adhesive layer 1b suitable for the temporary fixing sheet 10 can be formed.

[0083] <Base material formation process> The base material forming step is a step of forming the base material 1 by laminating a cushion layer 1a onto the adhesive layer 1b formed through the adhesive application step. After laminating the cushion layer 1a onto the adhesive layer 1b, it is preferable to perform aging to form the base material 1. The aging temperature is preferably 30 to 55°C, more preferably 35 to 50°C, and specifically, for example, 30, 35, 40, 45, 50, or 55°C, and may be within a range between any two of the values ​​exemplified here. The aging time is preferably 25 to 150 hours, more preferably 45 to 130 hours, and specifically, for example, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, or 150 hours, and may be within a range between any two of the values ​​exemplified here. By setting the aging temperature and aging time within the above ranges, it is possible to form a substrate 1 suitable for the temporary fixing sheet 10.

[0084] 3. Semiconductor wafer manufacturing method A method for manufacturing a semiconductor wafer using the temporary fixing sheet 10 will be described with reference to the drawings. This manufacturing method includes a frame attaching step, a wafer attaching step, a heating step, and a grinding step. This manufacturing method may further include a cutting step, a resin curing step, a dicing step, etc. The order in which these steps are performed can be changed as appropriate. Each step will be described below.

[0085] <Frame attachment process> 2A and 2B, in the frame attaching step, the temporary fixing sheet 10 is attached to a ring frame 3. The ring frame 3 has an opening 3a with a smaller diameter than the pressure-sensitive adhesive layer 2, and the ring frame 3 can be attached to the pressure-sensitive adhesive layer 2. This allows the temporary fixing sheet 10 to be stably held by the ring frame 3, making it easy to handle the temporary fixing sheet 10.

[0086] <Wafer bonding process / heating process> As shown in FIGS. 2B and 2C, in the wafer bonding step, the temporary fixing sheet 10 is bonded to the surface (first surface) of the semiconductor wafer 4 on which the convex portions 5 are provided, under reduced pressure.

[0087] This step can be performed by attaching the semiconductor wafer 4 to the temporary fixing sheet 10 in a decompression chamber 16. The pressure in the decompression chamber 16 needs only to be lower than atmospheric pressure, and is preferably 1000 Pa or less, more preferably 500 Pa or less, and even more preferably 100 Pa or less. The lower limit of the pressure in the decompression chamber 16 is not particularly limited, but is, for example, 10 Pa.

[0088] By attaching the semiconductor wafer 4 to the temporary fixing sheet 10 under reduced pressure in this manner, the inside of the sealed space 2b surrounded by the semiconductor wafer 4 and the temporary fixing sheet 10 becomes a reduced pressure state.

[0089] When the temporary fixing sheet 10 with the semiconductor wafer 4 attached thereto is removed from the decompression chamber 16 and exposed to atmospheric pressure, the substrate 1 is pushed by the atmospheric pressure and attempts to enter the sealed space 2b. The substrate 1 has high rigidity when not heated, and therefore does not enter the sealed space 2b at all. On the other hand, when the substrate 1 is heated to 60 to 150°C in the heating step, the substrate 1 is softened and enters the sealed space 2b as shown in FIG. 2D. Therefore, the protrusions 5 are embedded in the substrate 1 and are protected by the substrate 1. The ratio of the height of the embedded portion of the protrusions 5 to the total height of the protrusions 5 is preferably 0.2 to 1, more preferably 0.5 to 1, and even more preferably 0.8 to 1. The heating temperature of the substrate 1 is preferably 80 to 120°C. The heating time of the substrate 1 is preferably 3 to 120 seconds, more preferably 5 to 60 seconds.

[0090] The base material 1 may be heated before or after the semiconductor wafer 4 is attached to the temporary fixing sheet 10. Moreover, this heating may be performed inside or outside the decompression chamber 16.

[0091] <Cutting process> In the cutting step, the temporary fixing sheet 10 is cut along the outer periphery of the semiconductor wafer 4. As a result, the temporary fixing sheet 10 to which the semiconductor wafer 4 is attached is separated from the ring frame 3. The cutting step is not essential, but can be performed as needed, for example, after the heating step or the resin curing step described below.

[0092] <Grinding process> 3A and 3B, the grinding step grinds the back surface 4b of the semiconductor wafer 4. The semiconductor wafer 4 is fixed to the suction table 6 via a temporary fixing sheet .

[0093] The back surface 4b of the semiconductor wafer 4 is the surface (second surface) opposite to the surface (first surface) on which the protrusions 5 are provided. There are no particular limitations on the method for grinding the back surface of the wafer, and any known grinding method can be used. Grinding is preferably performed while cooling the wafer and grinding stone (diamond, etc.) by spraying water on them. The thickness of the thinned wafer is preferably 300 μm or less, and more preferably 150 μm or less.

[0094] During back grinding, a load is applied to the protrusions 5 in the in-plane direction of the semiconductor wafer 4, making the protrusions 5 prone to breakage. However, in this embodiment, at least a portion of the protrusions 5 is embedded in the base material 1 and the cured curable resin 8, and the protrusions 5 are stably supported by the base material 1 and the cured curable resin 8, making the protrusions 5 less likely to break. Note that if the support of the protrusions 5 by the base material 1 is unstable, the back grinding performance may decrease.

[0095] <Resin curing process> The method for manufacturing a semiconductor wafer may include a resin curing step. In order to prevent damage to the protrusions 5, in the resin curing step, the substrate 1 is brought into contact with the curable resin 8 after the wafer bonding step, and the curable resin 8 is cured in this state. The curable resin 8 is a resin that is cured by a stimulus such as energy rays (e.g., ultraviolet rays) or heat. The curable resin 8 is preferably supported on a support film 7 and disposed between the barrier layer 1c of the temporary fixing sheet 10 and the support film 7.

[0096] The curable resin 8 is a resin that is cured by stimulation with energy rays (for example, ultraviolet rays), heat, etc. The curable resin 8 is disposed between the substrate 1 and the support film 7.

[0097] The viscosity of the curable resin 8 before curing is preferably 100 to 3000 mPa·s, and more preferably 200 to 1000 mPa·s. When the viscosity is 100 mPa·s or higher, the curable resin 8 forms point contact rather than surface contact, which prevents air bubbles from being mixed in during the pressing process and provides excellent grindability. When the viscosity is 3000 mPa·s or lower, the curable resin 8 is less likely to entrap air bubbles when flowing between adjacent protrusions 5, providing excellent grindability. The viscosity is measured using an E-type viscometer at 23°C and 50 rpm.

[0098] The curable resin 8 preferably has a Shore D hardness of 5 to 70 after curing, and more preferably 10 to 60. When the Shore D hardness is 5 or more, the retention of the convex portions 5 is high, resulting in excellent grindability. When the Shore D hardness is 70 or less, the temporary fixing sheet 10 is easily curved when peeling it off from the semiconductor wafer 4. The Shore D hardness is measured under conditions in accordance with JIS K 6253.

[0099] The curable resin 8 is preferably a photocurable resin, more preferably an ultraviolet curable resin.

[0100] The curable resin 8 is preferably based on an acrylic resin, and although its composition is not particularly limited, a curable resin containing 1,2-hydrogenated polybutadiene-terminated urethane (meth)acrylate, isobornyl acrylate, or diethylacrylamide is preferred because it can improve the adhesion between the substrate 1 and the support film 7.

[0101] The cure shrinkage rate of the curable resin 8 is preferably 7% or less.

[0102] If the height of the protrusions 5 is Td (μm), the thickness of the curable resin 8 is preferably (Td+20) to (Td+200) μm, and more preferably (Td+50) to (Td+150) μm.

[0103] The support film 7 is any film capable of supporting the curable resin 8, and can be formed from polyolefins such as ethylene vinyl acetate, polyethylene, polypropylene, polybutene, polybutadiene, as well as polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyimide, etc.

[0104] The thickness of the support film 7 is preferably 10 to 300 μm, and more preferably 30 to 250 μm.

[0105] <Dicing process> As shown in Figures 4A to 4E, in the dicing step, the semiconductor wafer is divided into individual pieces. In the dicing step, the ground semiconductor wafer 4 is diced to divide the semiconductor wafer 4 into a plurality of semiconductor chips. The dicing method is not particularly limited, and may be any method such as blade dicing, laser dicing, stealth dicing, or plasma dicing.

[0106] The dicing step may include a coating step of coating the ground back surface 4b with a mask 8 that can form a dicing pattern (groove) using a patterning means (e.g., a laser) (FIG. 4A). The dicing pattern indicates the position where dicing will be performed. The mask 8 may be, for example, a (meth)acrylic copolymer. In the coating step, the ground semiconductor wafer 4 is fixed to an adsorption table 6' via a temporary fixing sheet 10.

[0107] The dicing step may also include a pattern formation step in which, after the coating step, a dicing pattern 8a is formed on the mask 8 by a pattern formation means (FIG. 4B). By dicing along this pattern 8a, the semiconductor wafer 4 can be easily divided into semiconductor chips of the desired size. In the pattern formation step, the ground semiconductor wafer 4 is fixed to the suction table 6'' via a temporary fixing sheet 10.

[0108] 4C shows a dicing step in which dicing is performed along the pattern 8a. The dicing step may further include a fixing step of fixing the semiconductor wafer 4 to a fixing table 7 (e.g., an electrostatic table or an adsorption table) via a temporary fixing sheet 10 before dicing.

[0109] After the dicing step, multiple semiconductor chips are attached to the temporary fixing sheet 10. For this reason, the dicing step may include a dicing tape application step of applying a dicing tape 9 to the back surface 4b of the diced semiconductor wafer 4 (FIG. 4D). The dicing tape 9 may be applied to the back surface 4b of the semiconductor wafer 4, or may be applied to the back surface 4b of the semiconductor wafer 4 and the ring frame 3. This prevents one or multiple semiconductor chips from remaining attached to the temporary fixing sheet 10 in a peeling step (described later) of peeling the temporary fixing sheet 10 from the semiconductor wafer 4. The dicing tape 9 may be, for example, an ultraviolet-curable dicing tape or a general pressure-sensitive dicing tape with low adhesive strength, and the base material of the dicing tape may be a polyolefin-based material such as polyvinyl chloride, polyethylene, or polypropylene. In the dicing tape application step, the semiconductor wafer 4 is fixed to a fixing table 6''' (e.g., an electrostatic table or a suction table) via the temporary fixing sheet 10.

[0110] <Peeling process> After the dicing step, a plurality of semiconductor chips are attached to the temporary fixing sheet 10. In this state, the peeling step (FIG. 4E) can be performed. In the peeling step, the temporary fixing sheet 10 is peeled off from the semiconductor wafer 4. The temporary fixing sheet 10 can be peeled off by bending the temporary fixing sheet 10 in a direction in which the temporary fixing sheet 10 moves away from the semiconductor wafer 4. This allows each of the plurality of semiconductor chips to be peeled off from the temporary fixing sheet 10. [Example]

[0111] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0112] 1. Manufacturing of temporary fixing sheet 10 Example 1 Preparation of cushion layer 1a First, a cushion layer 1a was prepared, which was made of a 150 μm-thick metal ion crosslinked ethylene-methacrylic acid copolymer (trade name: HMD-150, manufactured by Gunze). The ethylene-methacrylic acid copolymer had a methacrylic acid unit ratio of 15 mass%, an MFR (JIS K7210, 125°C / 10.0 kg load) of 5 g / 10 min, and a melting point (JIS K7121) of 72°C.

[0113] Formation of substrate 1 First, acrylic resin A-1 was obtained by copolymerizing the monomers butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate. The content of the structural units derived from each monomer was 77% by mass of butyl acrylate, 15% by mass of methyl methacrylate, 5% by mass of 2-hydroxyethyl methacrylate, and 3% by mass of glycidyl methacrylate, based on 100% by mass of the solids content of the acrylic resin. An adhesive was prepared by mixing 12 parts by mass of phenol novolac epoxy resin B-1 (trade name: DT-572, epoxy equivalent: 515-590, manufactured by Daito Sangyo Co., Ltd.) having a structure represented by chemical formula (1) and 6.4 parts by mass of polyalkylamine B-3 (trade name: P-4730, amine value: 335, manufactured by Daito Sangyo Co., Ltd.) with 100 parts by mass of the solids content of this acrylic resin A-1.

[0114] Next, the above adhesive was applied to the entire surface of a barrier layer 1c made of a 25 μm thick PET film (product name: Lumirror S10, thickness 25 μm, manufactured by Toray) and dried at 100°C for 1 minute to form an 8 μm thick adhesive layer 1b.

[0115] Next, the cushion layer 1a was attached onto the adhesive layer 1b, and the resulting mixture was aged in an atmosphere at 50°C for 120 hours to form the substrate 1.

[0116] Formation of adhesive layer 2 A liquid composition was prepared by mixing 54.4 parts by weight of hydrogenated polybutadiene diacrylate (Osaka Organic Chemical Co., Ltd., trade name BAC-45), 13.6 parts by weight of isodecyl acrylate (Osaka Organic Chemical Co., Ltd., trade name IDAA), 32 parts by weight of isobornyl acrylate (Osaka Organic Chemical Co., Ltd., trade name IBXA), 7 parts by weight of α-aminoalkylphenone (BASF, trade name Omnilat 379EG) as a photopolymerization initiator, 3 parts by weight of vinyl ether polymer (Kyoeisha Chemical Co., Ltd., FLOWLEN AC-903) as an antifoaming agent, and 3 parts by weight of isocyanate (Asahi Kasei Corporation, trade name "TPA-100") as a crosslinking agent. This composition was applied to the entire surface of substrate 1, irradiated with UV light, and aged at 40°C for 4 days to form a 10 μm thick pressure-sensitive adhesive layer 2.

[0117] <Example 2> A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that the thickness of the adhesive layer 1b was set to 20 μm.

[0118] Example 3 A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that the phenol novolac type epoxy resin B-3 was not used and 3 parts by mass of the phenol novolac type epoxy resin B-1 was mixed to produce an adhesive.

[0119] Example 4 A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that an adhesive was prepared by mixing 12 parts by mass of phenol novolac epoxy resin B-2 (trade name: DPPN-501H, epoxy equivalent: 166, manufactured by Nippon Kayaku Co., Ltd.) having a structure represented by chemical formula (2) instead of the phenol novolac epoxy resin B-1, and the thickness of the barrier layer 1c was set to 12 μm.

[0120] <Example 5> A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that a 12 μm thick PI film (product name: GF-050, manufactured by SKC KORON) was used as the barrier layer 1c.

[0121] Example 6 A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that a metal ion crosslinked ethylene-methacrylic acid copolymer (product name: HMD-80, manufactured by Gunze) having a thickness of 80 μm was used as the cushion layer 1a, and the thickness of the barrier layer 1c was set to 12 μm.

[0122] Example 7 The temporary fixing sheet 10 was produced in the same manner as in Example 6, except that a 150 μm thick PO-based film (product name: Artply A grade, manufactured by Diaplus Films) made of a soft polyolefin resin in which an elastomer was blended with a polyolefin resin was used as the cushion layer 1a.

[0123] Example 8 A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that the thickness of the adhesive layer 1b was set to 4 μm.

[0124] <Comparative Example 1> A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that acrylic resin A-2 having the composition shown in Table 1 was used instead of acrylic resin A-1.

[0125] <Comparative Example 2> A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that the phenol novolac epoxy resin B-1 and the polyalkylamine B-3 were not used.

[0126] <Comparative Example 3> A temporary fixing sheet 10 was produced in the same manner as in Example 1, except that an acrylic resin A-3 having the composition shown in Table 1 was used instead of the acrylic resin A-1, an isocyanate-based crosslinking agent B-4 (product name: L-45E, manufactured by Nippon Polyurethane) was used instead of the phenol novolac epoxy resin B-1 and the polyalkylamine B-3, and the thickness of the adhesive layer 1b was set to 10 μm.

[0127] 2. Backside grinding of semiconductor wafers Using the temporary fixing sheet 10 produced above, the backside of the semiconductor wafer 4 was ground by the following method.

[0128] <Frame attachment process> First, the temporary fixing sheet 10 was attached to the ring frame 3.

[0129] <Wafer bonding process / heating process> Next, the temporary fixing sheet 10 was attached to the outer peripheral portion 4a of the semiconductor wafer 4 on the surface on which the protrusions 5 of the semiconductor wafer 4 were formed in a decompression chamber 16. The semiconductor wafer 4 used had a diameter of 8 inches, a thickness of 725 μm, and bumps (protruding electrodes) formed at 65 μm intervals in an area other than the outer periphery 3.0 mm apart. The bumps (protruding electrodes) had a diameter of 130 μm and a height of 85 μm. The pressure in the decompression chamber 16 was 100 Pa. In the decompression chamber 16, the substrate 1 was heated at 130° C. for 1 minute.

[0130] Next, the temporary fixing sheet 10 to which the semiconductor wafer 4 was attached was taken out of the decompression chamber 16, and the temperature was lowered to 25°C.

[0131] <Cutting process> Next, the temporary fixing sheet 10 was cut along the outer periphery of the semiconductor wafer 4 to separate the ring frame 3 from the adhesive sheet 10.

[0132] <Resin curing process> Next, with the adhesive sheet 10 facing the curable resin 8 supplied on the support film 7, the adhesive sheet 10 was moved in the in-plane direction of the support film 7 to spread the curable resin 8. The curable resin 8 used was composed of 1,2-hydrogenated polybutadiene-terminated urethane (meth)acrylate, isobornyl acrylate, and diethylacrylamide. The viscosity of the curable resin 8 before curing (measured using an E-type viscometer at 23°C and 50 rpm) was 470 mPa s.

[0133] Next, the substrate 1 was brought into contact with the curable resin 8, and the curable resin 8 was cured to form a cured resin 18. The curable resin 8 was irradiated from the support film 7 side with an integrated light intensity of 2000 mJ / cm 2 at a wavelength of 365 nm. 2The cured resin 18 had a Shore D hardness (JIS K 6253) of 15.

[0134] <Grinding process> Next, the back surface of the semiconductor wafer 4 is ground until the thickness of the semiconductor wafer 4 becomes 100 μm. The back grinding was performed using a grinding machine (Disco Corporation back grinder DFG-841). I used it.

[0135] 3. Evaluation The produced temporary fixing sheet 10 was measured for various physical properties. It was also evaluated for bump followability and backside grindability. The results are shown in Table 1.

[0136] [Table 1]

[0137] Measurements of various physical properties and evaluations were carried out as follows.

[0138] <Glass transition temperature (Tg) of adhesive layer> Differential scanning calorimetry (DSC) was performed according to JIS K 7121: 1987. The intersection of the tangent to the baseline in the DSC curve and the tangent to the steeply declining position in the endothermic region due to the glass transition was taken as Tg.

[0139] <Shear storage modulus of adhesive layer at 150℃> The shear storage modulus of the adhesive layer at 150°C was measured under the following conditions. First, the adhesive layer was kept in a thermo-hygrostat chamber at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours. The resulting adhesive layer was used as a sample and subjected to dynamic viscoelasticity measurements in normal air (dry state). The dynamic viscoelasticity measuring device used was an "MCR 301" (manufactured by Anton Paar). (Measurement conditions) Measurement equipment: MCR 301 (manufactured by Anton Paar) Pretreatment: Keep in an atmosphere at a temperature of 23°C and a relative humidity of 50% for 40 hours Test mode: Shear Frequency: 1Hz Temperature range: 30℃~160℃ Heating rate: 2℃ / min Strain range: 0.10% Measurement interval: 1Point / ℃

[0140] <Oxygen permeability of the barrier layer> The oxygen permeability of the substrate 1 was measured at 25° C. and 0% RH (DRY) using an oxygen permeability measuring device (GTR-10XFKS manufactured by GTR Tech Co., Ltd.) by gas chromatography in accordance with JIS K 7126-2 (isobaric method).

[0141] <Adhesion strength between cushion layer and barrier layer> The adhesive strength between the cushion layer and the barrier layer was measured in accordance with the adhesive strength measurement method of JIS Z0237 (Method 4: Adhesion test method in which the release liner is peeled off at an angle of 180° to the adhesive surface of the tape). Specifically, the value when the barrier layer side was peeled off was taken as the measured value.

[0142] <Bump-following ability> After the temporary fixing sheet 10 was attached to the wafer surface on which the bumps were formed, and the temperature was lowered to 25°C, the bump tracking ability was evaluated based on the depth to which the temporary fixing sheet 10 had followed the bumps on the wafer, using the following criteria. ○: Following depth is 65 μm or more and less than 80 μm ×: The following depth is less than 65 μm or 80 μm or more

[0143] <Backside grinding ability> The backside grindability was evaluated by measuring the TTV (maximum thickness - minimum thickness) using a SemDex (thickness precision measuring device, manufactured by ISIS) and using the following criteria. ◎: TTV is less than 6 μm 〇: TTV is 6 to 15 μm ×: TTV is more than 15 μm [Explanation of symbols]

[0144] 1: substrate, 1a: cushion layer, 1b: adhesive layer, 1c: barrier layer, 1d: surface treatment layer, 2: adhesive layer, 2b: sealed space, 3: ring frame, 3a: opening, 4: semiconductor wafer, 4a: outer periphery, 4b: back surface, 5: convex portion, 6, 6', 6'', 6': suction table, 7: dicing table, 8: mask, 9: dicing tape, 10: temporary fixing sheet, 16: decompression chamber

Claims

1. A substrate used in a temporary fixing sheet for semiconductor processing, a cushion layer; an adhesive layer provided on the cushion layer; and a barrier layer provided on the opposite side of the adhesive layer from the cushion layer, The adhesive layer has a glass transition temperature of 15°C or less, The adhesive layer has a shear storage modulus of 100 kPa or more at 150°C, The oxygen permeability of the barrier layer measured based on JIS K 7126-2 (constant pressure method) at 25°C and 0% RH is 1000 ml / (m ２ 24h·atm) or less.

2. The substrate according to claim 1, A substrate, wherein the adhesive strength between the cushion layer and the barrier layer is 4.0 N / 20 mm or more, as measured by peeling the substrate at an angle of 180° from the barrier layer side in accordance with JIS Z0237.

3. A method for producing a substrate according to claim 1 or claim 2, The method includes an adhesive preparation step, an adhesive application step, and a base material formation step, In the adhesive preparation step, an acrylic resin having an epoxy group and a polyfunctional epoxy resin are mixed to prepare an adhesive; In the adhesive application step, the adhesive is applied onto the barrier layer, In the base material forming step, the cushion layer is bonded onto the adhesive applied onto the barrier layer to form the base material.

4. A method for producing a substrate according to claim 3, The method for producing a substrate, wherein the acrylic resin further has a hydroxy group.

5. A method for producing a substrate according to claim 3, The acrylic resin is a copolymer obtained by copolymerizing raw material monomers including butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, and glycidyl methacrylate, The method for producing a substrate, wherein the acrylic resin is a copolymer obtained by copolymerizing 75 to 85 parts by mass of butyl acrylate with 100 parts by mass of the raw material monomers in total.

6. A method for producing a substrate according to claim 3, The method for producing a substrate, wherein the polyfunctional epoxy resin is a phenol novolac epoxy resin.

7. A method for producing a substrate according to claim 3, The method for producing a substrate, wherein a polyfunctional amine compound is further added in the adhesive production step.

8. A method for producing a substrate according to claim 7, The method for producing a substrate, wherein the polyfunctional amine compound is a polyalkylamine.

9. A temporary fixing sheet for semiconductor processing, comprising the substrate according to claim 1 or 2 and a pressure-sensitive adhesive layer, The pressure-sensitive adhesive layer is provided on the opposite side of the cushion layer from the adhesive layer.

10. A method for manufacturing a semiconductor element using a temporary fixing sheet for semiconductor processing using the base material according to claim 1 or 2, The method includes a frame attaching step, a wafer attaching step, a heating step, and a grinding step, In the frame attaching step, the temporary fixing sheet is attached to a ring frame, In the wafer bonding step, the temporary fixing sheet is bonded under reduced pressure to a first surface of a semiconductor wafer on which a convex portion is provided, In the heating step, the substrate is heated, In the grinding step, a second surface of the semiconductor wafer opposite to the first surface is ground.

11. 11. The method for manufacturing a semiconductor device according to claim 10, The method further includes a cutting step and a resin curing step, In the cutting step, the temporary fixing sheet is cut along the outer periphery of the semiconductor wafer, In the resin curing step, the substrate is brought into contact with a curable resin after the wafer bonding step, and the curable resin is cured in this state.

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