Semiconductor processing sheet

Abstract

Provided is a semiconductor processing sheet comprising: a protective layer that contains a hydrophilic polymer and is bonded to a surface to be protected of an adherend; a base material layer that is arranged to face one surface of the protective layer; and an adhesive layer that is disposed between the base material layer and the protective layer and has an adhesive force that decreases as a result of being irradiated with active energy rays. When the adhesive layer and the protective layer are respectively subjected to dynamic viscoelasticity measurement, the Tanδ of the adhesive layer at 85°C is 0.35 or less, and the storage elastic modulus G' of the protective layer at 85°C is 150,000 Pa or less.

Description

Sheets for semiconductor processing Cross-reference of related applications

[0001] This application claims priority to Japanese Patent Application No. 2024-199848, which is incorporated into the description of this application by reference.

[0002] The present invention relates to a semiconductor processing sheet used, for example, when performing backgrinding on a semiconductor wafer.

[0003] Conventionally, semiconductor processing sheets used for manufacturing semiconductor devices are known. This type of semiconductor processing sheet comprises, for example, an adhesive layer that is bonded to the protective surface of a workpiece such as a semiconductor wafer, and a support material that overlaps one side of the adhesive layer.

[0004] This type of semiconductor processing sheet is used, for example, in the manufacturing process of a semiconductor device. Such a semiconductor device manufacturing method includes, for example, the steps of: attaching an adhesive layer of the semiconductor processing sheet to the protective surface of a semiconductor wafer, which is the adherend; processing the semiconductor wafer; and removing the adhesive layer from the protective surface of the semiconductor wafer. In this way, the semiconductor processing sheet can be used after being attached to the protective surface of the adherend and then removed from the protective surface. The adherend may be a semiconductor wafer or a package, and below, the adherend will also be simply referred to as the "workpiece."

[0005] As a semiconductor processing sheet used in the semiconductor device manufacturing method described above, for example, one is known to be used as a so-called backgrind tape when backgrinding a semiconductor wafer. For example, as this type of semiconductor processing sheet, a semiconductor processing sheet having a support material and an adhesive layer disposed on one surface of the support material is known (for example, Patent Document 1). Specifically, in the semiconductor processing sheet described in Patent Document 1, the other surface of the support material is the outermost surface, the coefficient of dynamic friction between this outermost surface and 1200-grit sandpaper is 1.40 or less, and the tensile breaking stress of the support material is 250 MPa or less. When the semiconductor processing sheet described in Patent Document 1 is used as described above, the adhesive layer is pressed against and attached to one side (the surface to be protected) of the semiconductor wafer, which is the workpiece. With the semiconductor processing sheet attached to the semiconductor wafer, the thickness of the semiconductor wafer is reduced by backgrinding. After that, the adhesive layer and support material are peeled off from the workpiece surface, and the semiconductor processing sheet is removed from one side of the semiconductor wafer.

[0006] Generally, backgrind tape is a laminate of a base layer and an adhesive layer, and is used by attaching the adhesive layer to the protective surface of a workpiece that has protrusions formed by bumps or the like. Therefore, when a part of the adhesive layer comes into contact with a protrusion, a difference in height may occur on the back surface of the base layer (the surface opposite to the adhesive layer side) depending on the shape of the protrusion. If backgrinding is performed on a workpiece when the difference in height on the back surface of the base layer is relatively large, the pressure applied to the workpiece surface will be uneven, and as a result, the thickness of the workpiece after grinding may vary. The difference between the maximum and minimum thickness of the workpiece after backgrinding is also called TTV (Total Thickness Variation) and is used as an indicator of the thickness accuracy of the workpiece after grinding. The semiconductor processing sheet described in Patent Document 1 has the above-described structure, and therefore, when used as backgrind tape, it can reduce the difference in workpiece thickness (TTV) after grinding.

[0007] Japanese Patent Application Publication No. 2023-148645

[0008] However, the semiconductor processing sheet described in Patent Document 1 focuses on the coefficient of dynamic friction on the surface of the support material in order to relatively reduce the difference in workpiece thickness (TTV) after grinding, but does not focus on the height difference on the back surface (outer surface) of the support material (base layer) when it is attached to the workpiece. The height difference on the back surface (outer surface) of the support material (base layer) affects the difference in workpiece thickness (TTV) after grinding. Furthermore, the semiconductor processing sheet described in Patent Document 1 has the problem of being cumbersome to use because the adhesive layer and support material are removed by peeling them off the workpiece surface. In addition, since a part of the adhesive layer may remain on the workpiece surface after peeling, it is also cumbersome to use because a further step is required to remove the residue. To address these problems, there is a demand for a semiconductor processing sheet that can be easily removed in whole or in part by a liquid containing water, for example.

[0009] Therefore, there is a need for a semiconductor processing sheet that can relatively minimize the height difference on the outer surface of the substrate layer when attached to a workpiece, and moreover, a semiconductor processing sheet that can be easily removed, at least partially, by a liquid containing water. However, such a semiconductor processing sheet has not yet been sufficiently studied.

[0010] Therefore, the object of the present invention is to provide a semiconductor processing sheet that can relatively reduce the height difference on the outer surface of the substrate layer when attached to a workpiece, and that can be easily removed at least partially by a liquid containing water.

[0011] To solve the above problems, the semiconductor processing sheet according to the present invention comprises a protective layer containing a hydrophilic polymer that is bonded to the protective surface of an adherend, a base layer arranged opposite one side of the protective layer, and an adhesive layer arranged between the base layer and the protective layer and whose adhesive strength decreases when irradiated with active energy rays, wherein when the adhesive layer and the protective layer are subjected to dynamic viscoelasticity measurement, the Tanδ of the adhesive layer at 85°C is 0.35 or less, and the storage modulus G' of the protective layer at 85°C is 150,000 Pa or less.

[0012] A schematic cross-sectional view of an example of a semiconductor processing sheet of this embodiment, cut in the thickness direction. A schematic cross-sectional view showing an example of a semiconductor wafer as the adherend. A schematic cross-sectional view showing the state after the protective surface of the semiconductor wafer has been protected with an example of a semiconductor processing sheet. A schematic cross-sectional view showing the grinding process being carried out using an example of a semiconductor processing sheet. A schematic cross-sectional view showing the state after the bonding process has been carried out using an example of a semiconductor processing sheet. A schematic cross-sectional view showing the peeling process of the removal process being carried out using an example of a semiconductor processing sheet. A schematic cross-sectional view showing an example of how the protective layer of the semiconductor processing sheet is broken into smaller pieces. A schematic cross-sectional view showing another example of how the protective layer of the semiconductor processing sheet is broken into smaller pieces. A schematic cross-sectional view showing how the protective layer of the semiconductor processing sheet is removed by the dissolution process of the removal process. A schematic cross-sectional view showing a modified example of how the protective layer of the semiconductor processing sheet is removed by the dissolution process of the removal process.

[0013] Hereinafter, an embodiment of the semiconductor processing sheet according to the present invention will be described with reference to the drawings. Note that the figures in the drawings are schematic diagrams and do not necessarily have the same aspect ratio as the actual product.

[0014] As shown in Figure 1, the semiconductor processing sheet 1 of this embodiment comprises at least a protective layer 12 containing a hydrophilic polymer, a base layer 11 facing one side of the protective layer 12, and an adhesive layer 13 disposed between the base layer 11 and the protective layer 12, the adhesive strength of which decreases when irradiated with active energy rays. The semiconductor processing sheet 1 may further comprise an intermediate layer 14 disposed between the adhesive layer 13 and the base layer 11, as shown in Figure 1, for example. The semiconductor processing sheet 1 may further comprise a release liner 15 overlapping the other side of the protective layer 12, as shown in Figure 1, for example.

[0015] The semiconductor processing sheet 1 of this embodiment is used, for example, by being bonded to one side of an object to be protected (hereinafter also referred to as the protected surface). Specifically, the protective layer 12 can be used by being bonded to the protected surface. The protective layer 12 can be used as a pressure-sensitive sheet adhesive that adheres to the protected surface by being pressed against it.

[0016] The semiconductor processing sheet 1 of this embodiment can be used, for example, in the application of backgrind tape.

[0017] The semiconductor processing sheet 1 is used, for example, to temporarily protect the surface of an object to be protected. Examples of objects to be deposited include glass substrates, silicon wafers, stainless steel (SUS) substrates, organic material substrates, or ceramic substrates.

[0018] The adherend is not particularly limited as long as it is a workpiece. Examples of workpieces include semiconductor wafers for obtaining semiconductor chips, linked circuit boards composed of multiple linked circuit boards, or circuit boards. The surfaces of these substrates to be protected usually have irregularities.

[0019] The semiconductor wafer W, which serves as the adherend S, is configured as shown in Figure 2, for example. The semiconductor wafer W shown in Figure 2 comprises a semiconductor wafer body W1 and a plurality of electrode portions W2 arranged on one surface of the semiconductor wafer body W1. For example, in the semiconductor wafer W, the surface on which the plurality of electrode portions W2 are arranged is the surface to be protected.

[0020] Each electrode section W2 has multiple bump electrodes, and adjacent bump electrodes are arranged with relatively narrow spacing between them. In other words, multiple bump electrodes are arranged at high density in each electrode section W2. Since the multiple bump electrodes are usually formed by plating one side of the semiconductor wafer body W1, the multiple electrode sections W2 are formed to protrude outward from one side of the semiconductor wafer body W1. The protrusion height of each bump electrode (height from the surface of the semiconductor wafer body W1 to the tip of the bump electrode) is, for example, 10 μm to 200 μm. In this type of semiconductor wafer W, the side on which the bump electrodes are arranged becomes the surface to be protected.

[0021] A semiconductor wafer W can be diced (divided) along a cleavage line D, for example, as shown in Figure 2, to form small semiconductor chips. Figure 2 shows a cleavage line D for obtaining a semiconductor chip having one electrode portion W2. The semiconductor chip will have at least one electrode portion W2.

[0022] The electrode portion W2 of the semiconductor chip will be electrically connected to the electrode portion of another component. Other components connected to the electrode portion W2 of the semiconductor chip include a circuit board or another semiconductor chip configured similarly to the semiconductor chip described above.

[0023] Examples of semiconductor chips include sensor chips that have sensor elements (for example, light-receiving elements and vibration elements). Examples of sensor chips include CMOS (Complementary Metal-Oxide Semiconductor) chips.

[0024] [Protective Layer] The protective layer 12 has adhesive properties that allow it to adhere closely to the surface of the substrate to be protected. By attaching the protective layer 12 of the semiconductor processing sheet 1 to the surface to be protected, it is possible to prevent foreign matter from adhering to the surface to be protected until the protective layer 12 that overlaps the surface to be protected is removed. The protective layer 12 also has adhesive properties that allow it to adhere to the adhesive layer 13. Furthermore, the protective layer 12 of the semiconductor processing sheet 1 is used, for example, to temporarily protect the surface to be protected as described above, and then removed with a liquid containing water. The method of using the semiconductor processing sheet 1 by attaching the protective layer 12 of the semiconductor processing sheet 1 to the substrate will be explained in detail later.

[0025] The protective layer 12 contains a hydrophilic polymer. The hydrophilic polymer has hydrophilic groups in its molecule. Examples of hydrophilic groups include hydroxyl groups, carboxyl groups, sulfol groups, or polyoxyethylene groups.

[0026] The thickness of the protective layer 12 is, for example, 1 μm or more and 100 μm or less. Such a thickness is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Alternatively, the thickness of the protective layer 12 is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less. If the protective layer 12 is a laminate, the above thickness is the total thickness of the laminate. The thickness of the protective layer 12 is determined by arithmetic mean of the measured thickness of at least 5 randomly selected locations. A thinner protective layer 12 is easier to remove with a liquid containing water.

[0027] The storage modulus G' of the protective layer 12 at 85°C is, for example, 5,000 Pa or more, preferably 8,000 Pa or more, and more preferably 10,000 Pa or more. A higher storage modulus of the protective layer 12 at 85°C further suppresses tearing when the protective layer 12 comes into contact with a protrusion on the surface to be protected. On the other hand, the storage modulus G' of the protective layer 12 at 85°C is 150,000 Pa or less, preferably 100,000 Pa or less, and more preferably 50,000 Pa or less. A lower storage modulus allows the protective layer 12 to penetrate more sufficiently into the recesses of the uneven surface to be protected, thus exhibiting better embedding properties. As a result, the height difference on the outer surface (back surface of the base layer) of the base layer 11 when the semiconductor processing sheet 1 is attached to the workpiece can be reduced.

[0028] The storage modulus (shear storage modulus) of the protective layer 12 is measured as follows. Specifically, in measuring the storage viscoelasticity of the protective layer 12, protective layers are stacked as needed to create a sheet-like measurement sample with a thickness of 250 μm to 350 μm. The measurement sample is punched out with an 8 mm diameter punch to create a test piece. Then, dynamic viscoelasticity measurement is performed under the following measurement conditions, and the measured value [Pa] of the storage modulus at 85°C is read. Measurement device: Rheometer (e.g., HAAKE "MARS III") Measurement temperature: Heating from 40°C to 100°C (heating rate 10°C / min) Measurement frequency: 1 Hz (1 / sec) Strain: 5% Measurement gap: 0.250 mm Measurement mode: Shear mode Measurement terminal: Parallel plate with a measurement surface of 8 mm diameter

[0029] For example, the storage modulus G' [Pa] can be increased by increasing the molecular weight of the hydrophilic polymer contained in the protective layer 12. On the other hand, the storage modulus G' [Pa] can be decreased by decreasing the molecular weight of the hydrophilic polymer contained in the protective layer 12.

[0030] The protective layer 12 has a predetermined level of hydrophilicity. When the protective layer 12 has a predetermined level of hydrophilicity, at least a portion of the protective layer 12 usually dissolves in a liquid containing water. Because the protective layer 12 has a predetermined level of hydrophilicity, it is configured so that at least a portion of it dissolves and is removed from the surface of the adherend when it comes into contact with a liquid containing water.

[0031] The protective layer 12 preferably contains 90% by mass or more of a hydrophilic polymer, more preferably 95% by mass or more, and even more preferably 99% by mass or more. This allows the protective layer 12 to be more easily removed from the surface of the adherend when it comes into contact with a liquid containing water.

[0032] Examples of hydrophilic polymers include polyvinyl alcohol, polyethylene glycol, polyglycerol polyglycidyl ether, and water-soluble polyesters.

[0033] The degree of saponification [mol%] of polyvinyl alcohol is preferably 50 to 98, and more preferably 60 to 90. By having a degree of saponification within this range, the polyvinyl alcohol can have sufficient water solubility.

[0034] The degree of saponification of polyvinyl alcohol can be determined by proton magnetic resonance spectroscopy ( １ The degree of saponification can be measured by 1H-NMR. However, if the protective layer contains additives, the peak derived from the additives may overlap with the peak used to calculate the degree of saponification. In such cases, the protective layer sample should be subjected to methanol extraction or similar treatment to remove the additives before measuring the degree of saponification of polyvinyl alcohol. Specifically, the degree of saponification of polyvinyl alcohol can be measured under the following conditions: <Measurement conditions> ・Analytical instrument: e.g., FT-NMR: Bruker Biospin, AVANCE III-400 ・Observation frequency: 400MHz (1H) ・Measurement solvent: heavy water or heavy dimethyl sulfoxide (heavy DMSO) ・Measurement temperature: 80℃ ・Chemical shift standard: External standard TSP-d4 (0.00ppm) (when measuring heavy water) Measurement solvent (2.50ppm) (when measuring heavy DMSO)

[0035] The saponification degree of polyvinyl alcohol is calculated based on the following formula using the peak derived from the methylene group of the vinyl alcohol unit (VOH) (heavy water: 2.0 to 1.0 ppm, heavy DMSO: 1.9 to 1.0 ppm) and the peak derived from the acetyl group of the vinyl acetate unit (VAc) (near 2.1 ppm in heavy water, around 2.0 ppm in heavy DMSO). In the following formula, [VOH(-CH2)-] is the intensity of the peak derived from -CH2- in the vinyl alcohol unit. [VAc(CH3CO-)] is the peak intensity derived from CH3CO- in the vinyl acetate unit.

[0036]

[0037] The mass average molecular weight Mw of polyvinyl alcohol is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, and particularly preferably 4,000 or more. Such a mass average molecular weight Mw may be 15,000 or less, may be 10,000 or less, may be 8,000 or less, or may be 6,000 or less. When the mass average molecular weight Mw of polyvinyl alcohol is within the above numerical range, the protective layer 12 containing such polyvinyl alcohol has good shape retention and can be formed with a thickness closer to being uniform.

[0038] The average degree of polymerization of polyvinyl alcohol is preferably 50 or more, more preferably 70 or more, and still more preferably 90 or more. Such an average degree of polymerization may be 1,000 or less, may be 800 or less, may be 600 or less, may be 400 or less, may be 200 or less, or may be 150 or less. When the average degree of polymerization is within the above numerical range, polyvinyl alcohol can have sufficient water solubility. Also, the protective layer 12 containing such polyvinyl alcohol can have good moldability.

[0039] The mass average molecular weight Mw and the average degree of polymerization of polyvinyl alcohol can be measured by aqueous gel permeation chromatography (aqueous GPC) according to the following measurement conditions. <Measurement Conditions> - Analytical apparatus: Agilent, 1260 Infinity - Columns: TSKgel G6000PWXL (manufactured by Tosoh Corporation) and TSKgel G3000PWXL (manufactured by Tosoh Corporation) Connect the above two columns in series. - Column temperature: 40 °C - Eluent: 0.2 M aqueous sodium nitrate solution - Injection volume: 100 μL - Detector: Differential refractometer (RI) - Standard samples: PEG standard sample and PVA standard sample

[0040] Specifically, the mass average molecular weight Mw and the average degree of polymerization of polyvinyl alcohol are measured as follows. (1) By GPC measurement using a PEG standard sample, the mass average molecular weight Mw of the sample to be measured (PVA) and the PVA standard sample are calculated respectively. The average degree of polymerization of the PVA standard sample is known. (2) A calibration curve is created using the average degree of polymerization of the PVA standard sample and the calculated mass average molecular weight Mw of the PVA standard sample. (3) Using the created calibration curve, the average degree of polymerization of the sample to be measured (PVA) is determined from the mass average molecular weight Mw of the sample to be measured (PVA).

[0041] The protective layer 12 may further contain, for example, polyethylene glycol (PEG) (e.g., having a molecular weight of less than 20,000) or polyglycerol polyglycidyl ether as a hydrophilic polymer in addition to polyvinyl alcohol.

[0042] In the present embodiment, the protective layer 12 may further contain, for example, a surfactant in addition to the above-described blending components.

[0043] (Base material layer) The base material layer 11 is composed of, for example, a resin film. The base material layer 11 may contain one type of resin or a plurality of types of resins. The base material layer 11 preferably contains 95% by mass or more of the resin, and more preferably 98% by mass or more.

[0044] Examples of resins included in the base layer 11 include resins having polar groups. By including a resin having polar groups in the base layer 11, the wettability of the surface of the base layer 11 is improved. In other words, the surface free energy of the base layer 11 may increase. It is preferable that the wettability of the surface of the base layer 11 is relatively high, as this can lead to better adhesion between the base layer 11 and the layer in contact with it.

[0045] Examples of resins having the polar groups mentioned above include polyester resins (such as PET). Polyester resins are preferred among such resins. The base layer 11 may be, for example, a polyester resin film.

[0046] The thickness of the substrate layer 11 may be, for example, 100 μm or more and 125 μm or less.

[0047] (Adhesive layer) The adhesive layer 13 may have pressure-sensitive adhesion. The adhesive layer 13 is a curing type that hardens upon irradiation with active energy rays. Such hardening reduces the adhesive strength of the adhesive layer 13.

[0048] The Tanδ (loss tangent) of the adhesive layer 13 at 85°C is 0.35 or less. Preferably, such Tanδ is between 0.02 and 0.20. Note that Tanδ is a value obtained through dynamic viscoelasticity measurement and is the ratio of the loss modulus G'' to the storage modulus G' (G'' / G'), as is generally known.

[0049] Because the above Tanδ is within the above numerical range, the height difference on the outer surface (back surface) of the substrate layer 11 when the semiconductor processing sheet 1 is attached to the workpiece can be made relatively small.

[0050] The Tanδ (loss tangent) of the adhesive layer 13 is obtained from the results measured by the same method as the viscoelasticity measurement method described above. However, the measurement conditions differ in that a sheet-like measurement sample is prepared with a thickness of approximately 800 μm, and the measurement gap is 750 μm.

[0051] For example, the above-mentioned Tanδ can be increased by reducing the amount of crosslinking agent contained in the adhesive layer 13. On the other hand, for example, the above-mentioned Tanδ can be decreased by increasing the amount of crosslinking agent contained in the adhesive layer 13.

[0052] The adhesive layer 13 contains, for example, a specific polymer as an adhesive. Preferably, the adhesive layer 13 contains at least an acrylic polymer (first acrylic polymer) as an adhesive.

[0053] The adhesive layer 13 may contain, for example, a polymer such as an acrylic polymer, elastomer, silicone, or polyvinyl ether, and an ultraviolet-curable monomer or oligomer. The adhesive layer 13 may also contain a base polymer having polymerizable carbon-carbon double bonds at the main chain ends or side chains. Examples of such base polymers include polymers in which polymerizable carbon-carbon double bonds have been introduced into acrylic polymers (acrylic copolymers), vinyl alkyl ethers, silicones, polyesters, polyamides, polyurethanes, or styrene-diene block copolymers.

[0054] The adhesive layer 13 includes, for example, an acrylic copolymer as the acrylic polymer, a crosslinking agent such as an isocyanate compound, and a polymerization initiator such as a photopolymerization initiator.

[0055] The above-mentioned acrylic copolymer preferably contains at least alkyl (meth)acrylate units and crosslinkable group-containing (meth)acrylate units as monomer units in its molecule. Note that "unit" and "monomer unit" refer to the units that constitute the main chain of the acrylic copolymer, and are structures derived from each monomer after polymerization of the monomers (e.g., 2-ethylhexyl acrylate, hydroxyethyl acrylate, etc.) used in the polymerization of the acrylic copolymer. Furthermore, the above-mentioned acrylic copolymer has each side chain within each monomer unit constituting the main chain.

[0056] In this specification, the term "(meth)acrylate" refers to at least one of methacrylate (methacrylic acid ester) and acrylate (acrylic acid ester). The same applies to the term "(meth)acrylic."

[0057] The alkyl (meth)acrylate units described above are derived from alkyl (meth)acrylate monomers. In other words, the alkyl (meth)acrylate unit is the molecular structure after the polymerization reaction of alkyl (meth)acrylate monomers. The notation "alkyl" represents the hydrocarbon portion that is esterified to (meth)acrylic acid.

[0058] The alkyl portion (hydrocarbon) in the alkyl (meth)acrylate unit may be a saturated hydrocarbon or an unsaturated hydrocarbon. The alkyl portion (hydrocarbon) in the alkyl (meth)acrylate unit may be a linear hydrocarbon, a branched hydrocarbon, or may contain a cyclic structure. The number of carbon atoms in the alkyl portion (hydrocarbon) in the alkyl (meth)acrylate unit may be between 4 and 22.

[0059] The above acrylic copolymer more preferably contains saturated alkyl (meth)acrylate units as alkyl (meth)acrylate units, wherein the alkyl portion is a saturated hydrocarbon having 6 to 18 carbon atoms.

[0060] In the above-mentioned acrylic copolymer, it is preferable that the proportion (on a molar basis) of alkyl (meth)acrylate units with 6 or more carbon atoms in the alkyl portion is the highest among all monomer units in the molecule. For example, alkyl (meth)acrylate units with 6 or more carbon atoms (preferably 8 or more) in the alkyl portion may account for 50% to 90% on a molar basis among all monomer units.

[0061] The saturated alkyl (meth)acrylate unit with 6 or more carbon atoms in the alkyl portion is a benzene ring and an ether bond (-CH ２ -O-CH ２ It is preferable that the molecule does not contain any polar groups such as -), -OH groups, and -COOH groups. In saturated alkyl (meth)acrylate units with 6 or more carbon atoms in the alkyl portion, the alkyl portion may be a saturated linear hydrocarbon or a saturated branched hydrocarbon composed of 6 to 10 carbon atoms, without containing any atoms other than C and H.

[0062] The above acrylic copolymer preferably contains saturated branched alkyl (meth)acrylate units with 6 to 10 carbon atoms in the alkyl portion as the alkyl (meth)acrylate units.

[0063] The structure of the alkyl portion (hydrocarbon portion) of the saturated branched alkyl (meth)acrylate unit described above may be any saturated branched alkyl structure, and may be an iso structure, sec structure, neo structure, or tert structure. Specifically, examples of saturated branched alkyl (meth)acrylate units include isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Among these, the 2-ethylhexyl (meth)acrylate unit is preferred.

[0064] The structure of the alkyl portion (hydrocarbon portion) of the saturated linear alkyl (meth)acrylate unit described above can be any saturated linear alkyl structure. Specifically, examples of saturated linear alkyl (meth)acrylate units include ethyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate.

[0065] The above-mentioned acrylic copolymer may contain one type of alkyl (meth)acrylate unit alone, or it may contain two or more types.

[0066] The crosslinkable group-containing (meth)acrylate unit has a hydroxyl group that can form a urethane bond by a urethane reaction, or a polymerizable group that can be polymerized by a radical reaction. More specifically, the crosslinkable group-containing (meth)acrylate unit has at least one of an unreacted hydroxyl group or a radically polymerizable carbon-carbon double bond as a polymerizable group. Preferably, a portion of the crosslinkable group-containing (meth)acrylate unit has an unreacted hydroxyl group, and another portion (all others) does not have a hydroxyl group but has a radically polymerizable carbon-carbon double bond.

[0067] The above-mentioned acrylic copolymer preferably has hydroxyl group-containing (meth)acrylate units in which a hydroxyl group is bonded to a hydrocarbon portion having 4 or fewer carbon atoms, as crosslinkable group-containing (meth)acrylate units. When the adhesive layer 13 contains an isocyanate compound, the isocyanate group of the isocyanate compound and the hydroxyl group of the hydroxyl group-containing (meth)acrylate unit can react readily. By having the acrylic copolymer having hydroxyl group-containing (meth)acrylate units and the isocyanate compound coexist in the adhesive layer 13, the adhesive layer 13 can be cured appropriately. As a result, the acrylic copolymer can gel sufficiently. Therefore, the adhesive layer 13 can exhibit adhesive performance while maintaining its shape.

[0068] The hydroxyl group-containing (meth)acrylate unit is preferably a hydroxyl group-containing C2-C4 alkyl (meth)acrylate unit in which an OH group is bonded to an alkyl portion having 2 to 4 carbon atoms. The notation "C2-C4 alkyl" indicates the number of carbon atoms in the hydrocarbon portion ester-bonded to (meth)acrylic acid. In other words, a hydroxyl group-containing C2-C4 alkyl (meth)acrylic monomer refers to a monomer in which (meth)acrylic acid and an alcohol (usually a dihydric alcohol) having 2 to 4 carbon atoms are ester-bonded. The same applies hereafter in this specification. The C2-C4 alkyl hydrocarbon portion is usually a saturated hydrocarbon. For example, the C2-C4 alkyl hydrocarbon portion is a linear saturated hydrocarbon or a branched saturated hydrocarbon. The C2-C4 alkyl hydrocarbon portion preferably does not contain polar groups such as oxygen (O) or nitrogen (N).

[0069] Examples of hydroxyl group-containing C2-C4 alkyl (meth)acrylate units include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxy-n-butyl (meth)acrylate, or hydroxyiso-butyl (meth)acrylate, which are all units of hydroxybutyl (meth)acrylate. The hydroxyl group (-OH group) may be bonded to the terminal carbon (C) of the hydrocarbon portion, or to a carbon (C) other than the terminal carbon of the hydrocarbon portion.

[0070] The above acrylic copolymer preferably contains polymerizable (meth)acrylate units having a radical polymerizable carbon-carbon double bond (polymerizable unsaturated double bond) in its side chain, as crosslinkable group-containing (meth)acrylate units.

[0071] Specifically, the polymerizable (meth)acrylate unit has a molecular structure in which the isocyanate group of an isocyanate group-containing (meth)acrylic monomer is urethane-bonded to the hydroxyl group in the hydroxyl group-containing (meth)acrylate unit described above.

[0072] The above-mentioned acrylic copolymer contains radical polymerizable carbon-carbon double bonds of crosslinkable group-containing (meth)acrylate units, allowing the adhesive layer 13 to be cured by irradiation with active energy rays (such as ultraviolet light). For example, irradiation with active energy rays such as ultraviolet light generates radicals from the photopolymerization initiator, and these radicals cause the acrylic copolymer to crosslink with each other. This reduces the adhesive strength of the adhesive layer 13 before irradiation to a lower level after irradiation. This also allows for good separation between the protective layer 12 and the adhesive layer 13. The active energy rays used may be ultraviolet light, radiation, or electron beams.

[0073] Polymerizable (meth)acrylate units can be prepared by a urethane reaction following a polymerization reaction for synthesizing acrylic copolymers. For example, polymerizable (meth)acrylate units can be obtained by copolymerizing an alkyl (meth)acrylate monomer with a hydroxyl group-containing (meth)acrylic monomer, and then urethane reacting the hydroxyl groups in some of the hydroxyl group-containing (meth)acrylate units with the isocyanate groups of the isocyanate group-containing polymerizable monomer.

[0074] The above-mentioned isocyanate group-containing (meth)acrylic monomer preferably has one isocyanate group and one (meth)acryloyl group in its molecule. An example of such a monomer is 2-methacryloyloxyethyl isocyanate.

[0075] In this embodiment, the acrylic copolymer may contain monomer units other than those described above. For example, it may contain units such as (meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, or acrylonitrile. The acrylic copolymer contains (meth)acryloylmorpholine units as monomer units, and the glass transition temperature or polarity of the acrylic copolymer can be controlled relatively easily by changing the composition ratio of (meth)acryloylmorpholine units in the acrylic copolymer.

[0076] In the acrylic copolymer contained in the adhesive layer 13, each of the above units (each constituent unit) is, １ H-NMR, １３ This can be confirmed by NMR analysis such as C-NMR, pyrolysis GC / MS analysis, and infrared spectroscopy. The molar proportion of the above units in acrylic copolymers is usually calculated from the blending amount (starting amount) when polymerizing the acrylic copolymer.

[0077] In the above-mentioned acrylic copolymer, it is preferable that the proportion of crosslinkable group-containing (meth)acrylate units among the total monomer units (100 moles) is 15 moles or more and 60 moles or less, and that 50% or more (molar equivalent) of the crosslinkable group-containing (meth)acrylate units form urethane bonds as described above. In other words, it is preferable that the above-mentioned acrylic copolymer contains 15 moles or more and 60 moles or less of crosslinkable group-containing (meth)acrylate units when the total monomer units are 100 moles, and that 50% or more of the crosslinkable group-containing (meth)acrylate units are polymerizable (meth)acrylate units having radical polymerizable carbon-carbon double bonds. This allows the adhesive strength between the protective layer 12 and the adhesive layer 13 before curing to be maintained, while improving the peelability between the protective layer 12 and the adhesive layer 13 after curing.

[0078] The above-mentioned acrylic copolymer preferably contains 10 to 50 moles of polymerizable (meth)acrylate units when the total monomer units are 100 moles. This allows the adhesive strength between the protective layer 12 and the adhesive layer 13 before curing to be maintained, while improving the peelability between the protective layer 12 and the adhesive layer 13 after curing.

[0079] The isocyanate compound that the adhesive layer 13 may further contain has multiple isocyanate groups in its molecule and functions as a crosslinking agent. The presence of multiple isocyanate groups in the molecule of the isocyanate compound allows for the crosslinking reaction between acrylic copolymers in the adhesive layer 13 to proceed. Specifically, the crosslinking reaction mediated by the isocyanate compound can be promoted by reacting one isocyanate group of the isocyanate compound with a hydroxyl group of an acrylic copolymer, and the other isocyanate group with a hydroxyl group of another acrylic copolymer. The isocyanate compound may also be a compound synthesized through a urethane reaction or the like.

[0080] Examples of isocyanate compounds include diisocyanates such as aliphatic diisocyanates, alicyclic diisocyanates, or aromatic aliphatic diisocyanates.

[0081] Furthermore, examples of isocyanate compounds include polymerized polyisocyanates such as dimers or trimers of diisocyanates, and polymethylene polyphenylene polyisocyanates.

[0082] In addition, examples of isocyanate compounds include polyisocyanates obtained by reacting an excess amount of the above-mentioned isocyanate compound with an active hydrogen-containing compound. Examples of active hydrogen-containing compounds include active hydrogen-containing low molecular weight compounds and active hydrogen-containing high molecular weight compounds. Allophanate-modified polyisocyanates and biuret-modified polyisocyanates can also be used as isocyanate compounds. The above-mentioned isocyanate compounds can be used individually or in combination of two or more.

[0083] As the above isocyanate compound, a reaction product of an aromatic diisocyanate and an active hydrogen-containing low molecular weight compound is preferred. Since the reaction rate of the isocyanate group in the reaction product of aromatic diisocyanate is relatively slow, excessive hardening of the adhesive layer 13 containing such a reaction product is suppressed. As the above isocyanate compound, one having three or more isocyanate groups in the molecule is preferred.

[0084] The polymerization initiator that may be included in the adhesive layer 13 is a compound that can initiate a polymerization reaction by the energy of active energy rays such as light. By including a polymerization initiator in the adhesive layer 13, for example, when light energy is applied to the adhesive layer 13, a crosslinking reaction between acrylic copolymers can be promoted. Specifically, the polymerization reaction between polymerizable groups can be initiated between acrylic copolymers having polymerizable (meth)acrylate units containing radical polymerizable carbon-carbon double bonds, thereby curing the adhesive layer 13. This reduces the tackiness of the adhesive layer 13, and the cured adhesive layer 13 can be easily peeled off one side of the protective layer 12. Examples of polymerization initiators include photopolymerization initiators. Examples of photopolymerization initiators include alkylphenone-based photopolymerization initiators. Examples of alkylphenone-based photopolymerization initiators include α-aminoalkylphenone-based photopolymerization initiators (product name "Omnirad 369E," etc.), α-hydroxyacetophenone-based photopolymerization initiators (product name "Omnirad 127D," etc.), or benzyl ketal-based photopolymerization initiators (product name "Omnirad 651," etc.). Commercially available products such as the "Omnirad series" from IGM Resins can be used as photopolymerization initiators.

[0085] On the other hand, for example, if the acrylic copolymer has an active hydrogen-containing group such as an -OH group or -COOH group in its molecule, and the adhesive layer 13 contains a crosslinking agent such as the isocyanate compound, the adhesive layer 13 can be cured by heat treatment, and the adhesive strength decreases as a result of curing.

[0086] The adhesive layer 13 may further contain other components in addition to those described above. Examples of other components include tackifiers, plasticizers, fillers, antioxidants, antioxidants, UV absorbers, light stabilizers, heat stabilizers, antistatic agents, surfactants, and light release agents. The types and amounts of other components may be appropriately selected depending on the purpose.

[0087] The thickness of the adhesive layer 13 may be, for example, 1 μm or more and 10 μm or less. Preferably, the thickness of the adhesive layer 13 is 3 μm or more. Preferably, the thickness of the adhesive layer 13 is 5 μm or less.

[0088] (Intermediate layer) The intermediate layer 14 includes, for example, at least an acrylic polymer (second acrylic polymer). As such an acrylic polymer, an acrylic copolymer similar to the acrylic copolymer contained in the adhesive layer 13 can be used. Such an acrylic copolymer preferably has alkyl (meth)acrylate units, hydroxyl group-containing (meth)acrylate units, and (meth)acrylic acid units as monomer units in its molecule, and more preferably has polyfunctional (meth)acrylate units in its molecule.

[0089] A polyfunctional (meth)acrylate monomer that forms a polyfunctional (meth)acrylate unit structure has multiple (meth)acryloyl groups in its molecule. The above polyfunctional (meth)acrylate monomer may be, for example, a difunctional (meth)acrylate monomer, a trifunctional (meth)acrylate monomer, or a tetrafunctional (meth)acrylate monomer. The number of functions refers to the number of (meth)acryloyl groups that each monomer has in its molecule.

[0090] Examples of bifunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dimethylol dicyclopentane di(meth)acrylate, or tricyclodecanedimethanol acrylate. Examples of trifunctional (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, or dipentaerythritol tri(meth)acrylate. Examples of tetrafunctional (meth)acrylate monomers include pentaerythritol tetra(meth)acrylate or dipentaerythritol tetra(meth)acrylate. Examples of pentafunctional (meth)acrylate monomers include dipentaerythritol penta(meth)acrylate. Examples of hexa-functional (meth)acrylate monomers include dipentaerythritol hexa(meth)acrylate.

[0091] If the acrylic polymer contained in the intermediate layer 14 has polyfunctional (meth)acrylate units in its molecule, the acrylic polymer may have a network-like molecular structure.

[0092] The acrylic polymer contained in the intermediate layer 14 preferably has saturated linear alkyl (meth)acrylate units with 2 to 6 carbon atoms in the alkyl portion, hydroxyl group-containing (meth)acrylate units, (meth)acrylic acid units, and trifunctional or tetrafunctional (meth)acrylate units in its molecule. The saturated linear alkyl (meth)acrylate units are preferably at least one of ethyl (meth)acrylate units and n-butyl (meth)acrylate. The polyfunctional (meth)acrylate monomer that forms the trifunctional or tetrafunctional (meth)acrylate units is preferably trimethylolpropane tri(meth)acrylate.

[0093] The thickness of the intermediate layer 14 may be, for example, 50 μm or more and 150 μm or less. The thickness of the intermediate layer 14 is preferably 90 μm or more. The thickness of the intermediate layer 14 is preferably 130 μm or less.

[0094] In the semiconductor processing sheet 1, the ratio of the thickness of the protective layer 12 to the thickness of the adhesive layer 13 is preferably 2.0 to 4.0. This improves the embedding of the protective layer 12 into recesses on the workpiece surface when the semiconductor processing sheet 1 is attached to the workpiece. It also suppresses the intrusion of water between the protective layer 12 and the workpiece during the backgrinding process. In the semiconductor processing sheet 1, the ratio of the thickness of the intermediate layer 14 to the thickness of the adhesive layer 13 is preferably 18.0 to 26.0. This allows the intermediate layer 14 to function sufficiently as a stress relaxation layer when the semiconductor processing sheet 1 is attached to the workpiece, resulting in better embedding into recesses on the workpiece surface. Therefore, the height difference on the outer surface (back surface of the base layer) of the base layer 11 can be reduced. In the semiconductor processing sheet 1, the ratio of the thickness of the base layer 11 to the thickness of the adhesive layer 13 is preferably 20.0 to 25.0. This makes it possible to further suppress the deformation of the adhesive layer 13 (and possibly the intermediate layer 14) when the semiconductor processing sheet 1 is attached to the workpiece. Therefore, the height difference on the outer surface (back surface of the base layer) of the base layer 11 can be made smaller. The thickness of the semiconductor processing sheet 1 is preferably 200 μm or more and 250 μm or less.

[0095] (Release Liner) The release liner 15 can be a resin film containing the same material as the base layer 11 described above. Preferably, the release liner 15 is a resin film with a surface release treatment. The release liner 15 is used to protect the protective layer 12 and is peeled off, for example, immediately before the protective layer 12 is bonded to the adherend.

[0096] The semiconductor processing sheet 1 of this embodiment can be manufactured by a general method, for example, as follows. If necessary, to produce an intermediate layer 14, a polymer solution is prepared by dissolving the above-mentioned second acrylic polymer (acrylic copolymer) in an organic solvent. The second acrylic polymer can be prepared by a polymerization method using a general polymerization reaction. The polymer solution is applied to one side of the base layer 11, and the organic solvent is evaporated to form an intermediate layer 14 superimposed on the base layer 11. To produce an adhesive layer 13, a polymer solution is prepared by dissolving the above-mentioned first acrylic polymer (acrylic copolymer) in an organic solvent. The first acrylic polymer can be prepared by a polymerization method using a general polymerization reaction. The polymer solution is applied to the intermediate layer 14 (or base layer 11) produced as described above, and the organic solvent is evaporated to form an adhesive layer 13. To produce a protective layer 12, a hydrophilic polymer is dissolved in a solvent containing water, for example. Heating may be used when dissolving. In addition to water, an organic solvent may be used as the solvent. As the organic solvent, an aqueous organic solvent that dissolves in water in any proportion is preferred. Examples of such aqueous organic solvents include methanol, ethanol, and isopropyl alcohol. Next, the polymer solution prepared as described above is applied (coated) to, for example, a release liner. After application, a protective layer 12 is formed on top of the release liner by heating at a temperature at which the solvent evaporates. Finally, the protective layer 12 on the release liner and the adhesive layer 13 on the base layer 11 (or the intermediate layer 14 on the base layer 11, if applicable) are bonded together, and then the release liner is removed to produce the semiconductor processing sheet 1. Alternatively, the semiconductor processing sheet 1 may be produced by forming a laminate of the adhesive layer and the intermediate layer on the release liner, then transferring the intermediate layer side of the laminate to one side of the base layer, and then peeling off the release liner to reveal the adhesive layer, onto which the protective layer is then bonded. The semiconductor processing sheet 1 can be produced in this way, but the method for producing the semiconductor processing sheet is not limited to the method exemplified above.

[0097] The semiconductor processing sheet 1 is used, for example, as an auxiliary tool for manufacturing semiconductor devices. The semiconductor processing sheet 1 is used temporarily, for example, during the manufacturing process of a semiconductor device. Therefore, the manufactured semiconductor device does not have the semiconductor processing sheet 1.

[0098] A semiconductor device may be, for example, a semiconductor integrated circuit equipped with a semiconductor chip, a device equipped with a system LSI having complementary MOS (CMOS), or a device equipped with a device (MEMS Micro Electro Mechanical System) in which mechanical components, sensors, actuators, or electronic circuits are integrated on a single silicon substrate, glass substrate, or organic material substrate by microfabrication technology. The manufactured semiconductor device may also be a device equipped with a circuit board.

[0099] Various substrates can be used as the substrate to which the protective layer 12 of the semiconductor processing sheet 1 of this embodiment is bonded. Examples of substrates include, as described above, semiconductor wafers, circuit boards, or connected circuit boards (such as pseudo-wafers) which are composed of multiple circuit boards connected together.

[0100] Next, a method for manufacturing a semiconductor device using the semiconductor processing sheet 1 described above will be explained.

[0101] The above-described method for manufacturing a semiconductor device includes a temporary protection step of protecting the surface to be protected of an object with the above-described semiconductor processing sheet and then removing the semiconductor processing sheet, wherein the temporary protection step comprises an adhesion step of bonding the protective layer of the semiconductor processing sheet to the surface to be protected of the object, and a removal step of removing the semiconductor processing sheet from the surface to be protected, wherein the removal step comprises a step of peeling off at least the substrate layer and the adhesive layer from the protective layer (hereinafter also referred to as the peeling step), and a step of dissolving at least a part of the protective layer with a liquid containing water to remove the protective layer (hereinafter also referred to as the dissolving step).

[0102] The above-described method for manufacturing a semiconductor device may, if necessary, include a processing step for processing the adherend between the attachment step and the removal step. As an example of the processing step, a grinding step may be performed to reduce the thickness of the semiconductor wafer (workpiece) to which the semiconductor processing sheet 1 is attached.

[0103] In the above-described method for manufacturing a semiconductor device, at least one surface of a flat substrate (such as a semiconductor wafer) is protected by a protective layer 12. The protected surface (protected surface) may be only one side of the substrate or both sides. Circuit components (described in detail later) may or may not be arranged on the protected surface.

[0104] The material of the adherend is not particularly limited. Examples of adherend materials include glass, silicon, stainless steel (SUS), plastic, or ceramic. Examples of adherends include semiconductor wafers, sensor wafers such as CMOS or MEMS, imitation wafers, or circuit boards.

[0105] In the above bonding process, the protective layer 12 may be applied to the surface of the adherend (workpiece such as a semiconductor wafer) on the side where at least one of the circuit wiring, sensor part, and electrode part is arranged as a circuit component. For example, the protective layer 12 may be applied to one side (protection target surface) of the substrate on which the circuit wiring is arranged, or to one side of the substrate on which the sensor part is arranged, or to one side of the substrate on which the electrode part is arranged. In the above bonding process, it is preferable to apply the protective layer 12 to at least one side of the adherend so as to cover the circuit wiring, sensor part, or electrode part with the protective layer 12. Examples of circuit components include circuit wiring, electrode parts, or elements such as transistors, diodes, or sensor parts (such as light receiving sensors or vibration sensors).

[0106] The following will explain in detail using the example of manufacturing a semiconductor integrated circuit as a semiconductor device. In the following example, the semiconductor processing sheet 1 has the structure shown in Figure 1, and the substrate to which the protective layer 12 of the semiconductor processing sheet 1 is bonded is a semiconductor wafer, and the surface to be protected has irregularities formed by bumps, etc.

[0107] Generally, a semiconductor device manufacturing method comprises a front-end process in which a circuit surface is formed on one side of a bare wafer using highly integrated electronic circuits, and a back-end process in which chips are cut out from the semiconductor wafer on which the circuit surface has been formed and assembled.

[0108] In the preceding process, a circuit surface is formed on one side of a bare wafer to create a semiconductor wafer W to be used as the substrate. Circuit components such as bumps, electrodes, pillar terminals, or semiconductor chips may be placed on the circuit surface. As a result, the side on which the circuit components such as bumps are placed will have irregularities. In this embodiment, a semiconductor wafer W with one side having irregularities as the surface to be protected is used as the substrate. Such a semiconductor wafer W is further processed in a subsequent process.

[0109] In subsequent processes, at least two temporary protection steps are performed: an adhesion step in which the protective layer 12 of the semiconductor processing sheet 1 is bonded to the surface of the semiconductor wafer W, which is the adherend, and a removal step in which the semiconductor processing sheet 1 bonded to the surface is removed. In the removal step, a peeling step is performed in which at least the base layer 11 and the adhesive layer 13 are peeled off from the semiconductor processing sheet 1 bonded to the surface of the semiconductor wafer W, and a dissolution step is performed in which at least a portion of the protective layer 12 is dissolved with a liquid containing water to remove the protective layer 12 bonded to the surface. If necessary, between the peeling step and the dissolution step, a blade dicing process following laser grouping in laser ablation processing, or plasma dicing of the semiconductor wafer W may be performed. Note that when the dissolution step is performed, the protective layer 12 may be fragmented by a fragmentation step. In other words, in the dissolution step, the fragmented pieces 12' of the protective layer may be removed with a liquid containing water.

[0110] The subsequent steps described above include, for example, the bonding step, the grinding step, a mounting step in which the semiconductor wafer is fixed by bonding the side of the semiconductor wafer opposite to the side to be protected to the adhesive fixing layer 22 of the dicing tape 20, a peeling step in the removal step, a fragmentation step in which at least the protective layer 12 is fragmented into smaller pieces as necessary, a dissolution step in the removal step, and a removal step in which the semiconductor wafer W or semiconductor chip is peeled off and removed from the adhesive fixing layer 22 of the dicing tape 20. Semiconductor integrated circuits (semiconductor devices) are manufactured, for example, through these steps.

[0111] In the semiconductor device manufacturing method described above, the semiconductor device is manufactured as follows, using at least the protective layer 12 of the semiconductor processing sheet 1 and the dicing tape 20 (see Figure 3C). The dicing tape 20 has a base layer 21 and an adhesive fixing layer 22 and is used as an auxiliary tool for manufacturing the semiconductor device. A commercially available product can be used as the dicing tape 20.

[0112] In the application process, for example, as shown in Figure 3A, the protective layer 12 of the semiconductor processing sheet 1 is superimposed on the surface to be protected of the semiconductor wafer W. In the application process, for example, the protective layer 12 is superimposed on the surface to be protected by directly pressing it against the surface to be protected. By superimposing the protective layer 12 on the surface to be protected of the semiconductor wafer W, the surface to be protected can be protected by the protective layer 12 until the protective layer 12 is removed. Therefore, it is possible to prevent dust and other debris from adhering to the surface to be protected of the semiconductor wafer W covered with the protective layer 12.

[0113] In the bonding process, the protective layer 12 of the semiconductor processing sheet 1 is bonded to the protective surface of a semiconductor wafer W having protrusions such as bumps. At this time, a part of the protective layer 12 comes into contact with the protrusions, causing the protective layer 12 and the adhesive layer 13 to deform, and the thickness of the laminate of the semiconductor wafer W and the semiconductor processing sheet 1 tends to vary depending on the location. However, because the protective layer 12 and the adhesive layer 13 of the semiconductor processing sheet 1 have the physical properties described above, the laminate of the protective layer 12 and the adhesive layer 13 can be deformed appropriately while having appropriate rigidity. Therefore, the height difference on the outer surface (back surface of the base layer) of the base layer 11 when the semiconductor processing sheet 1 is bonded to the workpiece can be reduced.

[0114] In the grinding process described above, for example, with the semiconductor wafer W, protective layer 12, adhesive layer 13, intermediate layer 14, and base layer 11 stacked, grinding is performed on the surface of the semiconductor wafer W where no circuit components are placed. Specifically, as shown in Figure 3B, grinding is performed with a grinding pad K (back grinding) until the semiconductor wafer W reaches a predetermined thickness. The thickness of the semiconductor wafer W is reduced to a predetermined thickness by the grinding process.

[0115] In the mounting process, as shown in Figure 3C, the dicing ring R is attached to the adhesive fixing layer 22 of the dicing tape 20, while the semiconductor wafer W is attached and fixed to the adhesive fixing layer 22 of the dicing tape 20.

[0116] In the peeling step of the removal process, for example as shown in Figure 3D, the base layer 11, the intermediate layer 14, and the adhesive layer 13 are peeled off from the surface of the protective layer 12 before the protective layer 12 is removed from the surface of the semiconductor wafer W. In the peeling step, the adhesive layer 13 may be subjected to irradiation with active energy rays such as ultraviolet light before peeling off the base layer 11 and the adhesive layer 13. In this case, the adhesive layer 13 containing a photopolymerization initiator, as described above, is used.

[0117] After the peeling process described above, a fragmentation process is carried out as needed to further fragment the protective layer 12 into smaller pieces. For example, the semiconductor wafer W with the protective layer 12 attached may be fragmented into semiconductor chips (dies) by laser grouping and blade dicing.

[0118] In the fragmentation process, either only the protective layer 12, or the protective layer 12 and the semiconductor wafer W, are fragmented, for example, as shown in Figure 3E or Figure 3F. In the fragmentation process, for example, the semiconductor wafer W is fragmented using a blade after the laser grouping process described above. In the laser grouping process, for example, as shown in Figure 3E, the surface to be protected is protected by the protective layer 12 while the surface to be protected is irradiated with laser light L. For example, SiO ２ Laser grouping can be performed when an insulating film called a Low-k film, which has a lower dielectric constant than the dielectric constant of the semiconductor wafer, is present on the surface to be protected. The wiring layer containing the Low-k film is removed by laser light, and two narrow grooves are formed at intervals within the dicing street. After that, the semiconductor wafer W can be cut into smaller pieces using a blade. In laser grouping, foreign matter such as fragments of the insulating film may be generated when the laser light L is irradiated. At this time, since the surface to be protected of the semiconductor wafer W is protected by the protective layer 12, the adhesion of foreign matter to the surface to be protected can be suppressed.

[0119] In the fragmentation process, the semiconductor wafer W may be fragmented by laser dicing or plasma dicing. In laser dicing, the semiconductor wafer W can be fragmented by irradiating it with a laser. In plasma dicing, for example, the semiconductor wafer W can be fragmented by etching it by irradiating it with plasma toward the protective layer 12 on the semiconductor wafer W. Plasma dicing is performed, for example, using a plasma generator in accordance with conventional methods.

[0120] In the fragmentation process, for example, as shown in Figure 3F, an expansion operation may be performed to stretch the dicing tape 20 in the planar direction to increase the surface area of ​​the dicing tape 20 while the semiconductor wafer W to which the protective layer 12 is attached is fixed on the adhesive fixing layer 22 of the dicing tape 20. This divides the laminate of the semiconductor wafer W and the protective layer 12 into smaller pieces, and further, the spacing between adjacent semiconductor chips X formed by the fragmentation may be widened along the planar direction. In some cases, the semiconductor wafer W needs to be fragmented by the above-mentioned expansion operation. Therefore, the semiconductor wafer W to be fragmented as described above may be designed to be easily cleaved. For example, a weak area is formed inside the semiconductor wafer W for fragmentation into semiconductor chips X (dies). The weak area (see cleavage line D shown in Figure 2) can be formed by irradiating the semiconductor wafer W with laser light using a commercially available stealth dicing apparatus. The protective layer 12 also needs to be fragmented by the above-mentioned expansion operation, so it is designed to be easily cleaved.

[0121] The details of the above expansion operation are as follows. For example, as shown in Figure 3F, after attaching the dicing ring R to the adhesive fixing layer 22 of the dicing tape 20, the dicing ring R is fixed to the holder H of the expansion device. The dicing tape 20 is stretched by pushing up the push-up member U of the expansion device from below the dicing tape 20, thereby spreading it in the planar direction. This causes the semiconductor wafer W and protective layer 12 to be broken into smaller pieces under specific temperature conditions. The above temperature conditions are, for example, -20°C to 0°C. The expanded state is released by lowering the push-up member U (this is the low-temperature expansion operation). Furthermore, under higher temperature conditions (for example, 10°C to 25°C), the dicing tape 20 is stretched to increase its surface area. This pulls adjacent semiconductor chips X apart in the planar direction of the dicing tape 20, further widening the kerf (spacing) (room temperature expansion operation). By stretching the dicing tape 20 in the planar direction to increase its surface area, the semiconductor wafer W can be divided into small semiconductor chips X using the aforementioned vulnerable areas within the semiconductor wafer as boundaries. At this time, the semiconductor wafer W is divided into semiconductor chips X, and the protective layer 12 is also divided into small pieces.

[0122] In the dissolution step of the removal process, for example, as shown in Figure 3G or Figure 3H, a liquid containing water is brought into contact with a plurality of small pieces 12' of the protective layer, and at least a portion of each small piece 12' is dissolved by the liquid, thereby removing each small piece 12' of the protective layer from the surface (protected surface) of the semiconductor wafer W or semiconductor chip X. By removing the small pieces 12' of the protective layer in this way, all of the plurality of small pieces 12' of the protective layer can be removed relatively easily, and the number of foreign matter adhering to the protected surface can be reduced relatively easily by the liquid. In addition, the surface (protected surface) of the semiconductor wafer W on which the protective layer 12 overlapped, or the surface (protected surface) of each semiconductor chip X on which the small pieces 12' of the protective layer overlapped can also be cleaned with the liquid.

[0123] In the dissolution step of the removal process, at least a portion of the fragmented protective layer (multiple small pieces 12' of the protective layer) is dissolved by the liquid. As a result, the adhesion of the small pieces 12' of the protective layer to the semiconductor chip X weakens, making them easier to peel off from the semiconductor chip X. This allows the multiple small pieces 12' of the protective layer to be removed relatively easily.

[0124] The liquid containing water is not particularly limited as long as it is a liquid substance containing water. Such a liquid may contain 30% by mass or more of water, 50% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. In addition to water, the above liquid may contain components that dissolve in water. Examples of such components include water-soluble organic solvents. Examples of such water-soluble organic solvents include monohydric alcohols with 4 or fewer carbon atoms, such as methanol, ethanol, propanols such as isopropyl alcohol, or butanols such as t-butanol.

[0125] In the dissolution step of the removal process, the protective layer pieces 12' may be immersed in the stirred liquid to bring the liquid into contact with the protective layer pieces 12'. Alternatively, the liquid sprayed from a nozzle or the like may be brought into contact with the protective layer pieces 12'. The temperature of the liquid is not particularly limited and may be set to, for example, 10°C or higher and 90°C or lower.

[0126] For example, in the dissolution step of the removal process, a disc-shaped stage supporting the dicing tape 20 from below is rotated circumferentially, and the liquid is sprayed toward the semiconductor wafer W or semiconductor chip X attached to the dicing tape 20. This makes it possible to remove multiple small pieces 12' of the protective layer that are superimposed on the semiconductor wafer W or semiconductor chip X, respectively. The rotation speed of the stage may be, for example, 500 rpm to 4000 rpm, the amount of liquid sprayed may be, for example, 0.05 L / min to 5.0 L / min, and the spraying time may be, for example, 5 seconds to 300 seconds.

[0127] According to the semiconductor device manufacturing method described above, a protective layer 12 is superimposed on the surface of the semiconductor wafer W on which circuit components are formed (the surface to be protected), so that the surface to be protected can be protected until the protective layer 12 is removed. Even if foreign matter is attached to the surface to be protected before the protective layer 12 is superimposed, that foreign matter can be removed when the small piece 12' of the protective layer superimposed on the surface to be protected is removed. Therefore, it is possible to suppress the adhesion of foreign matter to the surface to be protected of the manufactured semiconductor chip X. Specifically, it is possible to suppress the adhesion of foreign matter to protrusions such as bumps.

[0128] In the extraction process, the semiconductor wafer W or semiconductor chip X is peeled off the adhesive fixing layer 22 of the dicing tape 20. When performing the extraction process, it is necessary that the semiconductor wafer W or semiconductor chip X be easily peeled off the adhesive fixing layer 22 of the dicing tape 20. The dicing tape 20 is designed to exhibit this performance well. For example, the dicing tape 20 is configured such that when irradiated with active energy rays (e.g., ultraviolet light), the adhesive fixing layer 22 hardens and the adhesive strength of the adhesive fixing layer 22 decreases. Because the adhesive strength of the adhesive fixing layer 22 can be reduced by hardening after irradiation, the semiconductor wafer W or semiconductor chip X can be peeled off the adhesive fixing layer 22 relatively easily after irradiation. Dicing tapes 20 with such a configuration are commercially available.

[0129] While the semiconductor processing sheet in the embodiment of the present invention is as illustrated above, the present invention is not limited to the semiconductor processing sheet illustrated above. That is, various forms used in general semiconductor processing sheets can be adopted as long as they do not impair the effects of the present invention.

[0130] The matters disclosed herein include: (1) A semiconductor processing sheet comprising: a protective layer containing a hydrophilic polymer that is bonded to the surface of an adherend; a base layer disposed opposite one side of the protective layer; and an adhesive layer disposed between the base layer and the protective layer and whose adhesive strength decreases upon irradiation with active energy rays, wherein when the adhesive layer and the protective layer are subjected to dynamic viscoelasticity measurement, the Tanδ of the adhesive layer at 85°C is 0.35 or less, and the storage modulus G' of the protective layer at 85°C is 150,000 Pa or less. The semiconductor processing sheet having the above configuration can reduce the height difference on the outer surface of the base layer when it is attached to a workpiece, and at least a portion of it can be easily removed with a liquid containing water. In other words, the semiconductor processing sheet having the above configuration reduces the height difference on the outer surface of the base layer when it is attached to a workpiece, and at least the protective layer can be easily removed with a liquid containing water. (2) The semiconductor processing sheet according to (1), wherein the Tanδ of the adhesive layer is 0.02 or more and 0.20 or less. (3) The semiconductor processing sheet according to (1) or (2), wherein the protective layer contains polyvinyl alcohol as the hydrophilic polymer.

[0131] The present invention will be further explained with experimental examples, but the present invention is not limited to these.

[0132] The semiconductor processing sheets for the examples and comparative examples were manufactured as follows: [Examples 1-8, Comparative Examples 1-4] A protective layer, an adhesive layer, and an intermediate layer were prepared according to the compositions shown in Tables 1 and 2, respectively, and semiconductor processing sheets comprising a base layer, intermediate layer, adhesive layer, and protective layer in this order were manufactured.

[0133] <Base layer> Resin film (made of polyethylene terephthalate), thickness 100 μm. Product name: "AC Aopet 100" (manufactured by Panac Co., Ltd.)

[0134] <Raw materials for forming a protective layer> (Hydrophilic polymer) ・Polyvinyl alcohol (PVA) Product name "JMR-3M" (manufactured by Nippon Vinegar & Polyval Co., Ltd.) Saponification degree: 65%, Polymerization degree: 100 ・Polyvinyl alcohol (PVA) Product name "JMR-20M" (manufactured by Nippon Vinegar & Polyval Co., Ltd.) Saponification degree: 65%, Polymerization degree: 400 ・Polyvinyl alcohol (PVA) Product name "LM-10HD" (manufactured by Kuraray Co., Ltd.) Saponification degree: 40% ・Polyvinyl alcohol (PVA) Product name "LM-20" (manufactured by Kuraray Co., Ltd.) Saponification degree: 40% ・Polyethylene glycol (PEG-600) Molecular weight: Approximately 600, Viscosity: 10 mPa·s Commercial reagent ・Polyglycerol polyglycidyl ether containing multiple ether groups and multiple hydroxyl groups in the molecule Product name "Denacol" EX-521 (manufactured by Nagase ChemteX Corporation) Viscosity: 4400 mPa·s Water-soluble polyester (PES) Multiple ester groups and multiple -SO groups in the molecule ３ Na group-containing mass average molecular weight Mw: 14,000 Product name "Pluscoat Z-221" (manufactured by Go-o Chemical Industry Co., Ltd.) <Preparation of protective layer> Aqueous solutions of each polymer were prepared with the blending compositions shown in Tables 1 and 2 so that the total concentration of hydrophilic polymers was 20% by mass. The aqueous solutions of each polymer were heated to 60°C during preparation. The aqueous solutions of each polymer were applied to a release liner (PET film thickness 50 μm). The release liner had a surface treated with silicone release agent, and the aqueous solutions of the above polymers were applied to this surface using an applicator. Next, a drying treatment was performed at 130°C for 2 minutes to form a protective layer of a predetermined thickness ranging from 5 μm to 10 μm overlapping one side of the release liner.

[0135] <Preparation of the intermediate layer> Monomers: Butyl acrylate (BA): 50 parts by mass Ethyl acrylate (EA): 50 parts by mass Acrylic acid (AA): 4 parts by mass Hydroxyethyl acrylate (HEA): 0.1 parts by mass Trimethylolpropane triacrylate (TMPTA): 0.3 parts by mass Peroxide-based polymerization initiator Product name: "Niper BW" Manufactured by NOF Corporation Polymerization solvent Toluene Each monomer was placed in the above mass ratio in a reaction vessel equipped with a condenser, nitrogen inlet tube, thermometer and stirring device. 0.1 parts by mass of the above polymerization initiator was used as a thermal polymerization initiator for approximately 100 parts by mass of total monomers. Toluene was added as the reaction solvent so that the total monomer concentration reached a predetermined concentration (e.g., 30% by mass). Polymerization reaction treatment was carried out at 72°C for a predetermined time (e.g., 5 hours) in a nitrogen stream, and then at 82°C for a predetermined time (e.g., 2 hours) to synthesize an acrylic copolymer intermediate. Next, the following components were added to 100 parts by mass of this acrylic copolymer intermediate to prepare a composition for intermediate layer preparation. Then, the intermediate layer composition was applied to one side of the substrate layer, and the solvent was evaporated to create an intermediate layer on the substrate layer. • Photopolymerization initiator: 1 part by mass (α-aminoalkylphenone-based photopolymerization initiator) (Product name "Omnirad369E", manufactured by IGM Resins) • Crosslinking agent (polyisocyanate compound): 1 part by mass (Product name "Takenate D-101A", manufactured by Mitsui Chemicals)

[0136] <Preparation of the adhesive layer> [Monomer composition A] 2-ethylhexyl acrylate (2EHA): 88.8 parts by mass Hydroxyethyl acrylate (HEA): 11.2 parts by mass Peroxide-based polymerization initiator Product name "Niper BW" Manufactured by NOF Corporation Polymerization solvent Toluene The above raw materials were placed in a reaction vessel equipped with a cooling tube, nitrogen inlet tube, thermometer and stirring device. 0.2 parts by mass of the above polymerization initiator was used as a thermal polymerization initiator for 100 parts by mass of total monomers. Toluene was added as a reaction solvent so that the total monomer concentration reached a predetermined concentration (e.g., 36% by mass). Polymerization reaction treatment was carried out at 62°C for a predetermined time (e.g., 4 hours) in a nitrogen stream, and then at 75°C for a predetermined time (e.g., 2 hours) to obtain an acrylic copolymer intermediate. Note that in Example 2, Example 8, and Comparative Example 3, polymerization was carried out with the following monomer compositions. [Monomer Composition B] 2-Ethylhexyl acrylate (2EHA): 100 parts by mass Acryloyl morpholine (ACMO): 25.5 parts by mass Hydroxyethyl acrylate (HEA): 18.5 parts by mass

[0137] To the liquid containing the acrylic copolymer intermediate prepared as described above, 12.0 parts by mass of 2-methacryloyloxyethyl isocyanate (hereinafter also referred to as MOI) was added per 100 parts by mass of the total amount of 2EHA and HEA. In addition, 0.07% by mass of dibutyltin dilaurate was added as a reaction catalyst per 100 parts by mass of the acrylic copolymer. Subsequently, an addition reaction treatment (urethane reaction treatment) was carried out in an air stream at 50°C for 12 hours to obtain the acrylic copolymer. The average molecular weight of each acrylic copolymer is shown in Tables 1 and 2, respectively. In Example 2, Example 8, and Comparative Example 3, 22.5 parts by mass of 2-methacryloyloxyethyl isocyanate (hereinafter also referred to as MOI) was added per 100 parts by mass of 2EHA. Next, the following components were added to 100 parts by mass (solid content) of the acrylic copolymer to prepare a composition for making an adhesive layer. - Photopolymerization initiator: 5 parts by mass (α-hydroxyacetophenone-based photopolymerization initiator) (product name "Omnirad127D", manufactured by IGM Resins) - Crosslinking agent (polyisocyanate compound): Amount shown in Table 1 or Table 2 (product name "Takenate D-101A", manufactured by Mitsui Chemicals, Inc.) The adhesive layer composition prepared as described above was applied to the intermediate layer on the substrate layer prepared as described above, and heated and dried at 120°C for 2 minutes to produce an adhesive layer with a thickness of 5 μm.

[0138] <Manufacturing of Semiconductor Processing Sheets> Semiconductor processing sheets were manufactured by bonding an adhesive layer, which was formed overlapping an intermediate layer on a substrate layer, with a protective layer formed on a release liner. At this stage, the adhesive layer was cured by a curing treatment using activated energy rays.

[0139]

[0140]

[0141] (Tanδ of the adhesive layer at 85°C) Dynamic viscoelasticity measurements were performed according to the method described above, and the Tanδ of each adhesive layer at 85°C was measured. The results are shown in Tables 1 and 2.

[0142] (Shear storage modulus of protective layer at 85°C) Dynamic viscoelasticity measurements were performed according to the method described above, and the shear storage modulus of each protective layer at 85°C was measured. The results are shown in Tables 1 and 2.

[0143] <Evaluation of Embedding Ability> The embedding ability of each semiconductor processing sheet was evaluated for semiconductor wafers equipped with multiple bump electrodes on one side (hereinafter referred to as "semiconductor wafers with bump electrodes"). First, semiconductor processing sheets for each example and comparative example were prepared with a release liner attached to the protective layer. Next, semiconductor wafers with bump electrodes were fabricated as follows. Specifically, multiple regions with multiple bump electrodes were formed on one side of an 8-inch semiconductor wafer body. In the above regions, the diameter of the bump electrodes (bump diameter) was 25 μm, the distance between adjacent bump electrodes (bump pitch) was 80 μm (inter-bump distance was 30 μm), and the height from the flat portion on the surface of the semiconductor wafer (surface of the semiconductor wafer body) to the tip of the bump electrode was 55 μm. Subsequently, the protective layer of each semiconductor processing sheet was bonded to one side of the above semiconductor wafer body under the conditions of a pressure (laminate pressure) of 0.4 MPa and a roller temperature of 85°C. Then, the embedding performance was evaluated by observing the samples at a magnification of 200x using a digital microscope, according to the following criteria. The results are shown in Tables 1 and 2 below. (Evaluation Criteria) Good (○): No optical interference is observed. That is, the entire bump electrode is sufficiently embedded within the protective layer. Fairly Good (△): Some optical interference is observed around the outer periphery of each bump electrode. That is, although the area near the top of each bump electrode is sufficiently embedded within the protective layer, the outer periphery of each bump electrode is not sufficiently embedded. Poor (×): Clear voids are observed around the outer periphery of each bump electrode. That is, even the area near the top of each bump electrode is not sufficiently embedded within the protective layer.

[0144] <Evaluation of the height difference on the outer surface (back surface) of the base material layer>In the above evaluation of the embedding property, after each semiconductor processing sheet was bonded to one surface of the semiconductor wafer body, for the outer surface (back surface side surface) of the base material layer, a contact type line roughness meter (manufactured by Bruker, device name "DEKTAK8") was used to measure the surface unevenness. From the maximum value and the minimum value of the thickness, the height difference on the surface (back surface) of the base material layer was calculated and evaluated according to the following criteria. The results are shown in Table 1 and Table 2. (Measurement conditions) Scan type: Standard scan Stylus: Diameter 12.5 μm Stylus pressure: 5 mg (Evaluation criteria) Excellent (◎): Height difference is less than 9 μm Good (〇): Height difference is 9 μm or more and less than 10 μm Fair (△): Height difference is 10 μm or more and less than 12 μm Poor (×): Height difference is 12 μm or more

[0145] <Evaluation of the cleaning property (removability) of the protective layer with a liquid containing water>To remove the protective layer, a laminate of a silicon carrier wafer and the protective layer was immersed in water at 25°C for 30 seconds. Then, the water used to remove the protective layer was removed. Further, the surface of the silicon carrier wafer was analyzed with a Fourier transform infrared spectrophotometer (FT-IR). By such analysis, the presence or absence of residual organic substances was confirmed. The evaluation criteria are as follows. The results are shown in Table 1 and Table 2 below. (Evaluation criteria) Good (○): Almost no residual organic substances are observed (the maximum absorption at 800 - 4000 cm －１ is less than 0.1) Somewhat good (△): Residual organic substances are observed (the maximum absorption at 800 - 4000 cm －１ is 0.1 or more and 0.2 or less) Poor (×): Residual organic substances are observed (the maximum absorption at 800 - 4000 cm －１ is greater than 0.2)

[0146] As can be understood from the above evaluation results, when the semiconductor processing sheet of the example was attached to the surface to be protected (having convex portions) of the semiconductor wafer, the height difference on the outer surface (back surface side surface) of the base material layer was small. Also, the protective layer of the semiconductor processing sheet of the example was easily cleaned (removed) with water.

[0147] By manufacturing semiconductor devices using the semiconductor processing sheet described above, the height difference on the outer surface (back surface) of the substrate layer can be made relatively small. This allows for a relatively small difference in the thickness of the ground workpiece (TTV) after backgrinding of workpieces such as semiconductor wafers. Furthermore, semiconductor devices equipped with semiconductor chips that have almost no foreign matter attached can be manufactured efficiently.

[0148] The semiconductor processing sheet of the present invention is suitably used, for example, to manufacture semiconductor devices having semiconductor integrated circuits.

[0149] 1: Sheet for semiconductor processing, 11: Base layer, 12: Protective layer, 12': Small piece of protective layer, 13: Adhesive layer, 14: Intermediate layer, 15: Release liner, 20: Dicing tape, 21: Underlayment layer, 22: Adhesive fixing layer, W: Semiconductor wafer, X: Semiconductor chip.

Claims

1. A semiconductor processing sheet comprising: a protective layer containing a hydrophilic polymer that is bonded to the surface of an object to be protected; a base layer disposed opposite one side of the protective layer; and an adhesive layer disposed between the base layer and the protective layer, wherein the adhesive strength decreases when irradiated with active energy rays, wherein when the adhesive layer and the protective layer are subjected to dynamic viscoelasticity measurement, the Tanδ of the adhesive layer at 85°C is 0.35 or less, and the storage modulus G' of the protective layer at 85°C is 150,000 Pa or less.

2. The semiconductor processing sheet according to claim 1, wherein the Tanδ of the adhesive layer is 0.02 or more and 0.20 or less.

3. The semiconductor processing sheet according to claim 1 or 2, wherein the protective layer contains polyvinyl alcohol as the hydrophilic polymer.

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