Protective sheet and method for producing electronic component device

Abstract

The present invention provides, for example, a protective sheet comprising a protective layer which is bonded to a protection target surface of a substrate, wherein the protective layer contains a water soluble compound and the adhesive force of the protective layer with respect to a silicon wafer is not less than 0.5 N / 10mm.

Description

Protective sheet and method for manufacturing electronic component device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2023-208689, which is incorporated herein by reference.

[0002] The present invention relates to a protective sheet having a protective layer to be attached to a surface of a substrate to be protected, for example, and to a method for manufacturing an electronic component device, including a step of removing the protective sheet after attaching the protective layer of the protective sheet to the surface of the substrate to be protected.

[0003] Protective sheets used in manufacturing electronic component devices have been known. These protective sheets include, for example, a protective layer that is attached to a surface of the electronic component device to be protected, and a base layer that is overlaid on one side of the protective layer.

[0004] This type of protective sheet is used, for example, during a manufacturing process for an electronic component device. This manufacturing process for an electronic component device includes, for example, a step of mounting and temporarily fixing elements or the like as workpieces on one side of a substrate, a step of attaching a protective layer of the protective sheet to the other side (the surface to be protected) of the substrate, a step of processing the mounted elements or the like, a step of removing the elements or the like from the substrate, and a step of removing the protective layer from the substrate. For example, the protective sheet is attached to the substrate once and then removed from the substrate before use.

[0005] As a protective sheet used in the manufacturing method of the electronic component device described above, for example, a protective sheet including a base layer and a protective layer formed from a resin composition containing an oxyalkylene group-containing polyvinyl alcohol resin having a saponification degree of 55 mol% or less is known (for example, Patent Document 1). The protective sheet described in Patent Document 1 can be used by attaching the protective layer to one surface (the surface to be protected) of the substrate. The base layer of the protective sheet described in Patent Document 1 has relatively high adhesion to the protective layer, except when it is a release film.

[0006] According to the protective sheet described in Patent Document 1, the protective layer can protect the surface to be protected during temporary fixing, and further, the protective layer can be removed with water after temporary fixing.

[0007] Japanese Patent Application Publication No. 2021-161735

[0008] However, with the protective sheet described in Patent Document 1, if the surface to be protected of the substrate is uneven due to bumps or the like, the protective layer may not be able to deform sufficiently in accordance with the unevenness, and part of the protective layer may not fit into the recesses. In other words, the embedding ability of the protective layer is not necessarily good. Furthermore, the protective sheet described in Patent Document 1 can be used by peeling the base layer from the protective layer before removing the protective layer with water, leaving only the protective layer on the surface to be protected of the substrate. Even if only the protective layer is attached to the surface to be protected without the base layer, it can also be used by covering the protective layer with a covering tape and then peeling off only the covering tape. In such cases, when peeling the base layer or covering tape from the protective layer, the adhesion between the surface to be protected of the substrate and the protective layer is relatively low, so part of the protective layer may adhere to the peeled base layer or covering tape. To prevent such problems, there is a need for a protective sheet that has good embedding ability of the protective layer, has good peel resistance of the protective layer attached to the surface to be protected, and is easily removable by a liquid including water.

[0009] However, it cannot be said that sufficient research has yet been conducted into protective sheets that have good embedding properties for the protective layer, good peel resistance for the protective layer attached to the surface of the substrate to be protected, and that allow the protective layer to be easily removed by a liquid containing water.

[0010] Therefore, an object of the present invention is to provide a protective sheet that has good embedding properties for a protective layer, has good peel resistance for a protective layer attached to a surface of a substrate to be protected, and allows the protective layer to be easily removed by a liquid containing water, and also to provide a method for manufacturing an electronic component device using the above protective sheet.

[0011] In order to solve the above problems, the protective sheet of the present invention comprises a protective layer to be attached to a surface of a substrate to be protected, the protective layer contains a water-soluble compound, and the adhesive strength of the protective layer to a silicon wafer is 0.5 N / 10 mm or more.

[0012] The method for manufacturing an electronic component device according to the present invention includes a temporary protection step of protecting a surface of a substrate to be protected with a protective sheet and then removing the protective sheet, wherein the protective sheet comprises a protective layer containing a water-soluble polymer compound and a base layer overlapping one side of the protective layer, and the adhesive strength of the protective layer to the silicon wafer is 0.5 N / 10 mm or more, the temporary protection step includes a first step of bonding the protective layer of the protective sheet to the surface to be protected and a second step of removing the protective sheet from the surface to be protected, and the second step includes a step of peeling the base layer from the protective layer and a step of dissolving at least a portion of the protective layer with a liquid containing water to remove the protective layer.

[0013] 1 is a schematic cross-sectional view of an example of a protective sheet according to the present embodiment, cut in the thickness direction; FIG. 2 is a schematic cross-sectional view of another example of a protective sheet according to the present embodiment, cut in the thickness direction; FIG. 3 is a schematic cross-sectional view of another example of a protective sheet according to the present embodiment, cut in the thickness direction; FIG. 4 is a schematic cross-sectional view of an example of a semiconductor wafer as a substrate; FIG. 5 is a schematic cross-sectional view of an example of a substrate after the surface to be protected of the substrate has been protected with the example of the protective sheet; FIG. 6 is a schematic cross-sectional view of an example of a substrate after the protective layer has been cut into small pieces after the base layer has been removed; FIG. 7 is a schematic cross-sectional view of an example of a substrate after the protective layer has been cut into small pieces; FIG. 8 is a schematic cross-sectional view of an example of a substrate after the protective layer has been cut into small pieces; 1 is a schematic cross-sectional view showing a state after performing the first step (affixing step) using an example of a protective sheet; FIG. 2 is a schematic cross-sectional view showing a state where a peeling step of the second step (removing step) is performed using an example of a protective sheet; FIG. 3 is a schematic cross-sectional view showing an example of how the protective layer of the protective sheet is broken into small pieces; FIG. 4 is a schematic cross-sectional view showing another example of how the protective layer of the protective sheet is broken into small pieces; FIG. 5 is a schematic cross-sectional view showing how the protective layer of the protective sheet is removed by the dissolution step of the second step (removing step); FIG. 6 is a schematic cross-sectional view showing a modified example of how the protective layer of the protective sheet is removed by the dissolution step of the second step (removing step).

[0014] Hereinafter, embodiments of the protective sheet and the method for manufacturing an electronic component device according to the present invention will be described in order 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.

[0015] As shown in each of Figures 1A to 1C, the protective sheet 1 of this embodiment includes at least a protective layer 12 containing a water-soluble polymer compound. The protective sheet 1 of this embodiment may further include a substrate layer 11 overlying one side of the protective layer 12, as shown in each of Figures 1A and 1B, for example. The substrate layer 11 may include an adhesive layer 11b overlying one side of the protective layer 12 and a support layer 11a overlying the adhesive layer 11b, as shown in Figure 1A, for example. Alternatively, the substrate layer 11 may include only the support layer 11a, as shown in Figure 1B, for example. The protective sheet 1 of this embodiment may also include two release liners 15 overlying both sides of the protective layer 12, as shown in Figure 1C, for example.

[0016] The protective sheet 1 of this embodiment is used, for example, by being attached to one surface of a substrate to be protected (hereinafter also referred to as the surface to be protected). Specifically, the protective layer 12 can be attached to the surface to be protected. The protective layer 12 can be used as a pressure-sensitive sheet adhesive that can be adhered to the surface to be protected by being pressed against it.

[0017] The protective sheet 1 is used, for example, to temporarily protect the surface of a substrate to be protected, which is an adherend. Examples of the adherend substrate include a glass substrate, a silicon wafer, a stainless steel (SUS) substrate, an organic material substrate, and a ceramic substrate.

[0018] Specifically, examples of the substrate to be adhered include a semiconductor wafer for obtaining semiconductor chips, semiconductor chips obtained by cutting a semiconductor wafer into small pieces, a linked circuit board formed by linking multiple circuit boards, a circuit board, etc. The surface to be protected of these substrates usually has irregularities.

[0019] A semiconductor wafer W serving as a substrate S is configured, for example, as shown in FIG. 2 . The semiconductor wafer W shown in FIG. 2 includes a semiconductor wafer body W1 and a plurality of electrode portions W2 arranged on one surface of the semiconductor wafer body W1. In the semiconductor wafer W, the surface on which the plurality of electrode portions W2 are arranged serves as a circuit surface (circuit formation surface). Each electrode portion W2 has a plurality of bump electrodes, and adjacent bump electrodes are arranged at relatively narrow intervals. In other words, the plurality of bump electrodes are arranged at high density on each electrode portion W2. The plurality of bump electrodes are typically formed by plating one surface of the semiconductor wafer body W1, and therefore the plurality of electrode portions W2 are formed so as to protrude outward from one surface of the semiconductor wafer body W1. In this type of semiconductor wafer W, the surface on which the bump electrodes are arranged serves as the surface to be protected.

[0020] The semiconductor wafer W is diced (divided) into small semiconductor chips, for example, along a cutting line D shown in Fig. 2. Fig. 2 shows the cutting line D for obtaining semiconductor chips each having one electrode portion W2. Each semiconductor chip has at least one electrode portion W2.

[0021] The electrode portion W2 of the semiconductor chip is electrically connected to the electrode portion of another component. Examples of 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. For example, a semiconductor chip may have a pair of electrode portions arranged on both sides of the semiconductor chip body, and a conductive portion that penetrates the semiconductor chip body in the thickness direction to electrically connect the pair of electrode portions to each other. This type of semiconductor chip is called a TSV (Through Silicon Via) type. The electrode portion is electrically connected to another component. In a TSV type semiconductor chip, only one side may be a circuit surface, or both sides may be circuit surfaces. In a TSV type semiconductor chip, since electrode portions can be formed on both sides, both sides of the semiconductor chip can be surfaces to be protected.

[0022] The semiconductor chip may be a sensor chip having a sensor element (for example, a light receiving element or a vibration element), such as a CMOS (Complementary Metal-Oxide Semiconductor) chip.

[0023] For example, a semiconductor wafer W as shown in Fig. 2 may be used after one semiconductor chip is attached to each of a plurality of electrode portions W2 and the semiconductor chips are then sealed with resin. That is, a semiconductor wafer W as shown in Fig. 2 may be used as a substrate for a wafer level package (WLP). A wafer level package (WLP) is classified as the above-mentioned electronic component assembly.

[0024] The above-mentioned electronic component assembly may also be, for example, a pseudo wafer. The pseudo wafer may have, for example, a support substrate and a package formed by resin-sealing a plurality of semiconductor chips arranged on one surface of the support substrate. The pseudo wafer may be only the package removed from the support substrate. A rewiring layer may be formed on at least one surface of the pseudo wafer. In this case, the protective layer 12 may be used to protect the rewiring layer. Note that a divided body obtained by dividing the above-mentioned pseudo wafer so as to include at least one semiconductor chip may be a substrate.

[0025] The protective layer 12 has adhesive properties that allow it to adhere closely to the surface of the substrate to be protected. By laminating the protective layer 12 of the protective 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 overlying the surface to be protected is removed. Furthermore, the protective layer 12 can deform to accommodate the unevenness of the surface to be protected. Therefore, it can fully penetrate recesses and has good embedding properties. Furthermore, after being used to temporarily protect the surface to be protected, for example, as described above, the protective sheet 1 can be easily removed with a liquid containing water. The method of using the protective sheet 1, in which the protective layer 12 of the protective sheet 1 is laminated to the substrate to be protected, will be described in detail later.

[0026] [Base Layer of Protective Sheet] As described above, base layer 11 may be composed of only support layer 11a, or may be a laminate of support layer 11a and adhesive layer 11b.

[0027] The thickness of the base layer 11 is not particularly limited, but is, for example, 1 μm or more and 300 μm or less. Such a thickness may be 3 μm or more, or 5 μm or more. Also, such a thickness may be 40 μm or less. Note that when the base layer 11 is a laminate, the above thickness is the total thickness of the laminate.

[0028] (Support Layer of Base Material Layer) The support layer 11a of the base material layer 11 is composed of, for example, a resin film. The support layer 11a may contain one type of resin or multiple types of resin. The support layer 11a preferably contains 95% by mass or more of resin, and more preferably 98% by mass or more of resin.

[0029] The resin contained in the support layer 11a may be a resin having a polar group. When the support layer 11a contains a resin having a polar group, the wettability of the surface of the support layer 11a is improved. In other words, the surface free energy of the support layer 11a may be increased. It is preferable that the wettability of the surface of the support layer 11a is relatively high, since this may improve the adhesion between the support layer 11a and the adhesive layer 11b or the protective layer 12.

[0030] Examples of the resin having a polar group include polyester resin (e.g., PET), polyimide resin, and polyamide-imide resin. As such a resin, at least one of polyimide resin and polyester resin is preferred. For example, the support layer 11a may be a polyimide resin film, a polyamide-imide resin film, or a polyester resin film.

[0031] The thickness of the support layer 11a may be, for example, 5 μm or more and 50 μm or less.

[0032] (Adhesive Layer of Base Material Layer) The adhesive layer 11b has, for example, pressure-sensitive adhesive properties. The adhesive layer 11b contains, for example, at least an acrylic resin. The acrylic resin will be described in detail later.

[0033] The adhesive layer 11b may have a substantially non-reactive structure. This type of adhesive layer 11b may contain, for example, an acrylic resin and an isocyanate compound. In this case, the acrylic resin may not have a polymerizable group-containing (meth)acrylate structural unit (described in detail later) in the molecule.

[0034] On the other hand, the adhesive layer 11b may be configured so that a curing reaction proceeds when irradiated with active energy rays (such as ultraviolet rays), thereby reducing the adhesive strength. This type of adhesive layer 11b may contain, for example, an acrylic resin, an isocyanate compound, and a polymerization initiator (such as a photopolymerization initiator).

[0035] The acrylic resin has, for example, at least an alkyl (meth)acrylate structural unit, a hydroxyl group-containing (meth)acrylate structural unit, and a polymerizable group-containing (meth)acrylate structural unit in the molecule. The structural units are units that constitute the main chain of the acrylic resin.

[0036] The structural unit of the alkyl (meth)acrylate is derived from an alkyl (meth)acrylate monomer. In other words, the molecular structure obtained after the polymerization reaction of the alkyl (meth)acrylate monomer is the structural unit of the alkyl (meth)acrylate. The term "alkyl" refers to a hydrocarbon moiety ester-bonded to (meth)acrylic acid. The number of carbon atoms in the alkyl moiety may be 6 or more and 12 or less.

[0037] Examples of the structural unit of alkyl(meth)acrylate include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, pentyl(meth)acrylate, isopentyl(meth)acrylate, hexyl(meth)acrylate, heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, octyl(meth)acrylate, and isooctyl(meth)acrylate. Examples of structural units include acrylate, nonyl(meth)acrylate, isononyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, undecyl(meth)acrylate, dodecyl(meth)acrylate, tridecyl(meth)acrylate, tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, octadecyl(meth)acrylate, nonadecyl(meth)acrylate, and eicosyl(meth)acrylate.

[0038] The acrylic resin has a hydroxyl group-containing (meth)acrylate structural unit, and the hydroxyl group of this structural unit easily reacts with an isocyanate group. By allowing the acrylic resin having a hydroxyl group-containing (meth)acrylate structural unit and an isocyanate compound to coexist in the adhesive layer 11b, the adhesive layer 11b can be appropriately cured. This allows the adhesive layer 11b to be sufficiently gelled. As a result, the adhesive layer 11b can exhibit adhesive performance while maintaining its shape.

[0039] The structural unit of the hydroxyl group-containing (meth)acrylate is preferably a structural unit of a hydroxyl group-containing C2-C4 alkyl (meth)acrylate. The term "C2-C4 alkyl" refers to the hydrocarbon moiety ester-bonded to (meth)acrylic acid and its carbon number. In other words, a hydroxyl group-containing C2-C4 alkyl (meth)acrylate monomer refers to a monomer in which (meth)acrylic acid is ester-bonded to an alcohol (usually a dihydric alcohol) having 2 to 4 carbon atoms. The hydrocarbon moiety of the C2-C4 alkyl is usually a saturated hydrocarbon.

[0040] Examples of the structural unit of the hydroxyl group-containing C2 to C4 alkyl(meth)acrylate include structural units of hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, or hydroxybutyl(meth)acrylate such as hydroxy n-butyl(meth)acrylate or hydroxy isobutyl(meth)acrylate.

[0041] The acrylic resin contains a polymerizable group-containing (meth)acrylate structural unit having a polymerizable unsaturated double bond in the side chain. When the acrylic resin contains a polymerizable group-containing (meth)acrylate structural unit, radicals are generated from the photopolymerization initiator upon irradiation with active energy rays such as ultraviolet light, and the action of these radicals can cause a crosslinking reaction between the acrylic resins. This reduces the adhesive strength of the adhesive layer 11b upon irradiation. The active energy rays used may be ultraviolet light, radiation, or electron beams.

[0042] Specifically, the structural unit of the polymerizable group-containing (meth)acrylate may have a molecular structure in which an isocyanate group of an isocyanate group-containing (meth)acrylate monomer is urethane-bonded to a hydroxyl group in the structural unit of the hydroxyl group-containing (meth)acrylate described above.

[0043] The structural unit of the polymerizable group-containing (meth)acrylate having a polymerizable group can be prepared after the polymerization reaction for synthesizing the acrylic resin.For example, after copolymerization of an alkyl (meth)acrylate monomer and a hydroxyl group-containing (meth)acrylate monomer, the hydroxyl group in a part of the structural unit of the hydroxyl group-containing (meth)acrylate and the isocyanate group of the isocyanate group-containing polymerizable monomer are subjected to a urethane reaction, thereby obtaining the structural unit of the polymerizable group-containing (meth)acrylate.

[0044] The isocyanate group-containing (meth)acrylate monomer preferably has one isocyanate group and one (meth)acryloyl group in the molecule, such as 2-isocyanatoethyl (meth)acrylate.

[0045] The adhesive layer 11b may further contain an isocyanate compound. A portion of the isocyanate compound may be in a state after reaction such as urethane reaction. The isocyanate compound has multiple isocyanate groups in its molecule. When the isocyanate compound has multiple isocyanate groups in its molecule, it is possible to promote a crosslinking reaction between the acrylic resins in the adhesive layer 11b.

[0046] Examples of the isocyanate compound include diisocyanates such as aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Further examples of the isocyanate compound include polymerized polyisocyanates such as diisocyanate dimers and trimers, and polymethylene polyphenylene polyisocyanates. The above isocyanate compounds can be used alone or in combination of two or more.

[0047] The polymerization initiator that can be contained in the adhesive layer 11b is a compound that can initiate a polymerization reaction by applying heat or light energy. By including a polymerization initiator in the adhesive layer 11b, when heat energy or light energy is applied to the adhesive layer 11b, a cross-linking reaction between the acrylic resins can be promoted, and the adhesive layer 11b can be cured. This reduces the adhesive strength of the adhesive layer 11b, and allows the protective layer 12 and the cured adhesive layer 11b to be easily peeled apart. As the polymerization initiator, for example, a commercially available general photopolymerization initiator or thermal polymerization initiator can be used.

[0048] The adhesive layer 11b may further contain an additive such as an antioxidant, an ultraviolet absorber, or a surfactant.

[0049] The thickness of the adhesive layer 11b may be, for example, 5 μm or more and 150 μm or less.

[0050] [Protective Layer of Protective Sheet] The protective layer 12 contains, for example, a water-soluble polymer compound as a water-soluble compound. The water-soluble polymer compound has a hydrophilic group in the molecule. The protective layer 12 preferably contains 90% by mass or more of the water-soluble polymer compound, 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 by a liquid containing water.

[0051] The protective layer 12 includes, as water-soluble polymer compounds, a first water-soluble compound and a second water-soluble compound. The first water-soluble compound is preferably a compound having a polyoxyethylene structure in its molecule. The second water-soluble compound is preferably a water-soluble polyester resin having a mass-average molecular weight of 2,000 or more.

[0052] Both the first water-soluble polymer compound and the second water-soluble polymer compound have such water solubility that when a thin film (thickness of 50 μm or less) of each water-soluble polymer compound is immersed in water at 40° C., it is completely dissolved.

[0053] The protective layer 12 has a predetermined level of hydrophilicity or more. When the protective layer 12 has a predetermined level of hydrophilicity or more, typically, at least a portion of the protective layer 12 dissolves in a liquid containing water. Because the protective layer 12 has a predetermined level of hydrophilicity or more, the protective layer 12 is configured to be at least partially dissolved and removed from the surface of the substrate when it comes into contact with a liquid containing water.

[0054] The adhesion strength of the protective layer 12 to the silicon wafer is 0.5 [N / 10 mm] or more. Such adhesion strength is preferably 2.0 [N / 10 mm] or more, more preferably 3.0 [N / 10 mm] or more, and particularly preferably 5.0 [N / 10 mm] or more. By increasing the adhesion strength of the protective layer 12 to the silicon wafer, the protective layer 12 bonded to the surface of the substrate to be protected is more effectively prevented from being peeled off along with the base layer 11 when the base layer 11 or the like overlapping the protective layer 12 is peeled off from the protective layer 12. Furthermore, unintentional exposure of the surface of the protected silicon wafer can be more effectively prevented. The adhesion strength of the protective layer 12 to the silicon wafer may be 10.0 [N / 10 mm] or less.

[0055] For example, the adhesive strength can be increased by increasing the molecular weight of the water-soluble polymer compound contained in the protective layer 12. On the other hand, the adhesive strength can be decreased by decreasing the molecular weight of the water-soluble polymer compound contained in the protective layer 12.

[0056] The adhesion of the protective layer 12 to a silicon wafer (bare silicon wafer) is measured under the following measurement conditions. A protective sheet 1 having the configuration shown in FIG. 1C will be used as a specific example for explanation, but the above adhesion is measured in the same manner even when the protective sheet 1 has the configuration shown in FIG. 1A or 1B. First, one of the two release liners 15 is peeled from the protective layer 12 to expose one side of the protective layer 12. A backing tape is attached to this exposed surface to obtain a first test specimen. The backing tape is attached at a temperature of 25°C using a hand roller. Next, the first test specimen is cut to a width of 100 mm, and the other release liner is peeled from the protective layer 12 to expose the other side of the protective layer 12. This exposed surface is attached to a bare wafer to obtain a second test specimen (measurement sample). The bonding to the bare wafer is performed using a 2 kg standard roller (manual adhesion test press wheel adhesive tape adhesion tester) at a temperature of 90°C and a speed of 10 mm / sec. After bonding, the sample is allowed to cool naturally for 20 minutes or more. Next, the protective layer 12 and backing tape are peeled from the bare wafer at a temperature of 23°C, a peel angle of 180°, and a peel speed of 300 mm / min, and the peel force of the measurement sample is measured. The measured peel force is then used as the adhesion force. An Autograph (manufactured by Shimadzu Corporation) can be used as the measurement device, for example.

[0057] The storage modulus of the protective layer 12 at 70°C is preferably 100,000 Pa or less, and more preferably 50,000 Pa or less. When the storage modulus of the protective layer 12 at 70°C is 100,000 Pa or less, sufficient embedding properties can be exhibited even when the temperature when the protective layer 12 is attached to the surface to be protected is relatively low. The storage modulus of the protective layer 12 at 70°C may be 10,000 Pa or more.

[0058] For example, the storage modulus can be increased by increasing the molecular weight of the water-soluble polymer compound contained in the protective layer 12. On the other hand, the storage modulus can be decreased by decreasing the molecular weight of the water-soluble polymer compound contained in the protective layer 12.

[0059] 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, a protective layer is laminated as necessary to prepare a sheet-like measurement sample with a thickness of 250 μm or more and 350 μm or less. A test piece is prepared by punching out the measurement sample with an 8 mm diameter punch. Then, measurement is performed under the following measurement conditions, and the measured value (G') [Pa] of the storage modulus at 70°C is read. Measurement device: Rheometer (for example, "MARS III" manufactured by HAAKE) 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

[0060] In the protective sheet 1, the thickness of the protective layer 12 is not particularly limited, but is, for example, 1 μm or more and 100 μm or less. Such a thickness may be 3 μm or more, or 5 μm or more. Also, such a thickness may be 40 μm or less. When the protective layer 12 is a laminate, the above thickness is the total thickness of the laminate.

[0061] The first water-soluble compound is, for example, a compound having a polyoxyethylene structure in its molecule. The polyoxyethylene structure acts as a hydrophilic group. When the first water-soluble compound has a polyoxyethylene structure as a hydrophilic group in its molecule, it can be more easily soluble in a liquid containing water even at room temperature.

[0062] Examples of the first water-soluble compound include polyethylene glycol (PEG) (e.g., molecular weight less than 20,000) having only a polyoxyethylene structure in the molecule, polyethylene oxide (PEO) (e.g., molecular weight 20,000 or more) having only a polyoxyethylene structure in the molecule, and polyalkylene oxide copolymers (e.g., molecular weight 50,000 or more) having a polyoxyethylene structure and a polyoxypropylene structure in the molecule. The polyalkylene oxide copolymer may be a block copolymer having a block of a polyoxyethylene structure and a block of a polyoxypropylene structure in the molecule, or may be a random copolymer of ethylene oxide and propylene oxide.

[0063] The weight-average molecular weight Mw and average degree of polymerization of the first water-soluble compound exemplified above can be measured by aqueous gel permeation chromatography (aqueous GPC). The detailed measurement conditions are as follows. <Measurement Conditions> - Analytical Instrument: Agilent 1260Infinity - Column: TSKgel G6000PWXL and TSKgel G3000PWXL (Tosoh Corporation) The two columns are connected in series. - Column Temperature: 40°C - Eluent: 0.2 M aqueous sodium nitrate solution - Injection Volume: 100 μL - Detector: Differential Refractometer (RI) - Standard Sample: PEG Standard Sample The weight-average molecular weight Mw of the sample (PEG, PEO, etc.) is calculated by GPC measurement using the PEG standard sample.

[0064] When the water-soluble polymer compound has a polyoxypropylene structure in the molecule in addition to a polyoxyethylene structure, the adhesiveness of the protective layer 12 to the surface to be protected can be further improved. Also, the heat resistance of the protective layer 12 can be further improved.

[0065] The mass average molecular weight Mw of the polyethylene oxide (PEO) is preferably 200,000 (two hundred thousand) or less. By having a mass average molecular weight Mw of 200,000 or less, the first water-soluble compound can have a sufficiently low softening point. This can improve the adhesion of the protective layer 12 to the surface to be protected. Furthermore, the protective layer 12 can be efficiently removed from the surface to be protected in a shorter time using a liquid containing water. The mass average molecular weight Mw may be, for example, 50,000 or more.

[0066] As the first water-soluble compound, such as polyethylene glycol (PEG), polyethylene oxide (PEO), or polyalkylene oxide copolymer, commercially available products can be used.

[0067] The second water-soluble compound is, for example, a water-soluble polyester resin. The water-soluble polyester resin is a dehydration condensation product of at least a polycarboxylic acid (for example, terephthalic acid) and a polyol. The water-soluble polyester resin has a sulfo group (—SO ３ The alkyl group may have a carboxyl group (—H) or a carboxyl group (—COOH). These groups may be in the form of a salt.

[0068] A water-soluble polyester resin is water-soluble because it has the following physical properties. Specifically, the water-soluble polyester resin has at least one of the following physical properties (A) to (D): (A) When room temperature (23±2°C) water is sprayed onto the entire surface of a 20 μm-thick thin film formed from a water-soluble polyester resin at a spray pressure of 0.005 MPa for 20 minutes, the thin film completely dissolves in water. (B) When 50°C water is sprayed onto the entire surface of a 20 μm-thick thin film formed from a water-soluble polyester resin at a spray pressure of 0.005 MPa for 10 minutes, the thin film completely dissolves in water. (C) When a water-soluble polyester resin powder and room temperature water are mixed in a powder:water ratio of 1:5 by mass to obtain a mixed solution, and the mixed solution is irradiated with ultrasound for 20 minutes, the water-soluble polyester powder completely dissolves in water. (D) A water-soluble polyester resin powder and water at 50°C are mixed in a mass ratio of powder:water = 1:5 to obtain a mixed liquid, and when the mixed liquid is irradiated with ultrasound for 10 minutes, the water-soluble polyester powder is completely dissolved in the water.

[0069] The mass average molecular weight Mw of the water-soluble polyester resin may be 5,000 or more, 7,000 or more, or 10,000 or more. The mass average molecular weight Mw of the water-soluble polyester resin is preferably 40,000 (40,000) or less, more preferably 30,000 (30,000) or less, even more preferably 20,000 (20,000) or less, and particularly preferably 15,000 or less. When the mass average molecular weight Mw of the water-soluble polyester resin is 40,000 or less, the protective layer 12 can be easily formed into a film, and the embedding properties of the protective layer 12 can be improved. Furthermore, the protective layer 12 can more sufficiently prevent fine foreign matter from adhering to the surface to be protected. Furthermore, the protective layer 12 can be more easily removed by a liquid containing water.

[0070] The water-soluble polyester resin may be a resin exhibiting an acid value. The acid value of the water-soluble polyester resin may be 10 mgKOH / g or less. The acid value of the water-soluble polyester resin is a value measured according to the neutralization titration method specified in JIS K0070:1992.

[0071] As the water-soluble polyester resin which is the second water-soluble compound, a commercially available product can be used.

[0072] The protective layer 12 of this embodiment may further contain, in addition to the above-mentioned components, a surfactant, a plasticizer, and the like.

[0073] The protective layer 12 has adhesiveness that allows it to adhere to the surface of the substrate to be protected. When the base layer 11 has only the support layer 11a, the protective layer 12 has adhesiveness that allows it to adhere to the support layer 11a. When the base layer 11 has the support layer 11a and the adhesive layer 11b, the protective layer 12 and the adhesive layer 11b are in contact with each other, so the protective layer 12 has adhesiveness that allows it to adhere to the adhesive layer 11b.

[0074] 1B , the protective sheet 1 of this embodiment may include a release liner 15 that covers one surface of the protective layer 12 (the surface of the protective layer 12 that is not overlapping with the base layer 11) before use. The release liner 15 is used to protect the protective layer 12 and is peeled off immediately before the protective layer 12 is attached to, for example, a substrate.

[0075] The protective sheet 1 of this embodiment can be produced by a general method, for example, as follows. First, a water-soluble polymer compound is dissolved in a solvent containing water. Heat may be applied during dissolution. As the solvent, an organic solvent other than water may be used. The organic solvent is preferably an aqueous organic solvent that dissolves in water at any ratio. Examples of such aqueous organic solvents include methanol, ethanol, and isopropyl alcohol. Next, the polymer solution prepared as described above is applied (coated) to the base layer 11 or the release liner 15. After application, the solution is heated at a temperature at which the solvent volatilizes, thereby forming the protective layer 12 superimposed on the base layer 11 or the release liner 15. Although the protective sheet 1 can be produced in this manner, the method for producing the protective sheet is not limited to the method exemplified above.

[0076] The protective sheet 1 is used, for example, as an auxiliary tool for manufacturing an electronic component device. The protective sheet 1 is used, for example, temporarily during the process of manufacturing the electronic component device. Therefore, the manufactured electronic component device does not include the protective sheet 1.

[0077] The electronic component device may be, for example, a semiconductor device such as a semiconductor integrated circuit having a semiconductor chip, a device having a system LSI having a complementary MOS (CMOS), or a device having a device (MEMS Micro Electro Mechanical Systems) in which mechanical elements, sensors, actuators, or electronic circuits are integrated by microfabrication technology on a single silicon substrate, glass substrate, organic material substrate, etc. The manufactured electronic component device may also be a device having a circuit board.

[0078] Various substrates can be used as the substrate to which the protective layer 12 of the protective sheet 1 of this embodiment is attached, such as a semiconductor wafer, a circuit board, or a linked circuit board (e.g., a pseudo wafer) formed by connecting multiple circuit boards, as described above.

[0079] Next, a method for manufacturing the electronic component device of this embodiment will be described.

[0080] The method for manufacturing an electronic component device of this embodiment is a method for manufacturing an electronic component device, including a temporary protection step of protecting a surface of a substrate to be protected with a protective sheet and then removing the protective sheet, wherein the protective sheet comprises a protective layer containing a water-soluble polymer compound and a base layer overlapping one side of the protective layer, and the adhesive strength of the protective layer to the silicon wafer is 0.5 N / 10 mm or more, the temporary protection step includes a first step (hereinafter also referred to as a bonding step) of bonding the protective layer of the protective sheet to the surface to be protected, and a second step (hereinafter also referred to as a removal step) of removing the protective sheet from the surface to be protected, and the second step (removal step) includes a step (hereinafter also referred to as a peeling step) of peeling the base layer from the protective layer, and a step (hereinafter also referred to as a dissolving step) of dissolving at least a portion of the protective layer with a liquid containing water to remove the protective layer.

[0081] In the temporary protection step, for example, as shown in Fig. 3A , a protective sheet 1 having a base layer 11 on one side of a protective layer 12 may be used in the attachment step to attach the protective layer 12 of the protective sheet 1 to the surface to be protected of the substrate S, thereby protecting the surface to be protected of the substrate S. Thereafter, in the peeling step, for example, as shown in Fig. 3B , the base layer 11 is peeled off from the protective layer 12.

[0082] The manufacturing method for the electronic component device of this embodiment may further include a step of dividing at least the protective layer 12 into small pieces to produce a plurality of protective layer small pieces 12' (hereinafter also referred to as a small piece process), as shown in Figures 3C and 3D, respectively. In the small piece process, for example, as shown in Figure 3C, only the protective layer 12 of the stack of overlapping substrates S and protective layers 12 may be divided into small pieces to produce a plurality of small pieces 12'. On the other hand, for example, as shown in Figure 3D, a stack of overlapping substrates S and protective layers 12 may be divided into small pieces to produce a plurality of stacked small pieces of chips S' each composed of a small substrate and protective layer small pieces 12'.

[0083] In the above-mentioned temporary protection process, the dissolution process removes each small piece 12' of the protective layer overlapping the surface to be protected of the substrate S (such as the circuit surface of the chip S') using a liquid containing water, as shown in, for example, Figure 3E or Figure 3F.

[0084] In the method for manufacturing an electronic component device according to this embodiment, at least one surface of the substrate is protected by a protective layer 12. The surface to be protected (the surface to be protected) may be only one surface of the substrate or may be both surfaces. Note that a circuit component (described in detail below) may or may not be disposed on the surface to be protected.

[0085] The substrate may be made of any material, as long as it is plate-shaped. Examples of the substrate material include glass, silicon, stainless steel (SUS), plastic, and ceramic. Examples of the substrate include a semiconductor wafer, a sensor wafer such as a CMOS or MEMS, a pseudo wafer, and a circuit board.

[0086] In the above-mentioned attachment step, a protective layer 12 may be overlaid on the surface of the substrate on which at least one of the circuit wiring, sensor unit, and electrode unit is arranged as a circuit component. For example, the protective layer 12 may be overlaid on one side (circuit surface) of the substrate on which the circuit wiring is arranged, the protective layer 12 may be overlaid on one side of the substrate on which the sensor unit is arranged, or the protective layer 12 may be overlaid on one side of the substrate on which the electrode unit is arranged. In the above-mentioned attachment step, it is preferable to overlay the protective layer 12 on at least one side of the substrate so as to cover the circuit wiring, sensor unit, or electrode unit with the protective layer 12. Examples of circuit components include circuit wiring, electrode units, or elements such as transistors, diodes, or sensor units (such as light-receiving sensors or vibration sensors).

[0087] Hereinafter, a detailed description will be given of an example in which a semiconductor device (semiconductor integrated circuit) is manufactured as an electronic component device.

[0088] Generally, a method for manufacturing a semiconductor device includes 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.

[0089] In a pre-process, a circuit surface is formed on one side of a bare wafer to produce a semiconductor wafer W as a substrate. Circuit components such as bumps, electrodes, pillar terminals, or semiconductor chips may be arranged on the circuit surface. As a result, the surface on which the circuit surface is formed has irregularities. In this embodiment, a semiconductor wafer W having an irregular circuit surface formed on one side, which is the surface to be protected, is used as a substrate. Such a semiconductor wafer W is further processed in a post-process.

[0090] In the post-processing, at least a temporary protection process is performed, for example, including a bonding process in which the protective layer 12 of the protective sheet 1 is bonded to the surface (circuit surface) of the semiconductor wafer W as a substrate, and a removal process in which the protective layer 12 bonded to the surface (circuit surface) is removed. If necessary, a grinding process may be performed between the bonding process and the removal process to thin the thickness of the semiconductor wafer by grinding the semiconductor wafer with the protective sheet 1 bonded to it. The removal process includes a peeling process in which the base layer 11 is peeled off from the protective layer 12 bonded to the circuit surface of the semiconductor wafer W, and a dissolving process in which at least a portion of the protective layer 12 is dissolved using a liquid containing water to remove the protective layer 12 bonded to the circuit surface of the semiconductor wafer W. If necessary, a laser grouping process (described in detail below) or a plasma dicing process (described in detail below) of the semiconductor wafer W may be performed between the peeling process and the dissolving process. Note that the protective layer 12 may be fragmented by a fragmentation process before the dissolving process is performed. In other words, in the dissolving step, the fragmented protective layer fragments 12' may be removed by a liquid containing water.

[0091] The above-described post-processing steps include, for example, the above-described attachment step, the above-described grinding step which is performed as needed, a mounting step in which the surface of the semiconductor wafer opposite the circuit surface is attached to the adhesive fixing layer 22 of the dicing tape 20 to fix the semiconductor wafer, a peeling step in the above-described removal step, a dicing step which is performed as needed in which at least the protective layer 12 is diced into small pieces, a dissolving step in the above-described 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. A semiconductor integrated circuit (semiconductor device) is manufactured through, for example, these steps.

[0092] In the method for manufacturing a semiconductor device (electronic component device) of this embodiment, a semiconductor device is manufactured as follows using at least the protective layer 12 of the protective sheet 1 and a dicing tape 20 (see FIG. 4C ). The dicing tape 20 has a base layer 21 and the above-described adhesive fixing layer 22, and is used as an auxiliary tool for manufacturing a semiconductor device. Note that a commercially available product can be used as the dicing tape 20.

[0093] In the attachment step, as shown in Fig. 4A, for example, the protective layer 12 of the protective sheet 1 is superimposed on the circuit surface of the semiconductor wafer W. In the attachment step, for example, the protective layer 12 is superimposed on the circuit surface by directly pressing the protective layer 12 against the circuit surface and attaching it. By superimposing the protective layer 12 on the circuit surface of the semiconductor wafer W, the circuit surface can be protected by the protective layer 12 until the protective layer 12 is removed. This makes it possible to prevent dust and the like from adhering to the circuit surface of the semiconductor wafer W covered with the protective layer 12.

[0094] The grinding step is performed as necessary. For example, with the semiconductor wafer W, the protective layer 12, and the base layer 11 stacked, grinding is performed on the surface of the semiconductor wafer W on which no circuit components are arranged. More specifically, as shown in FIG. 4B , grinding (back grinding) is performed using a grinding pad K until the semiconductor wafer W reaches a predetermined thickness. The grinding step reduces the thickness of the semiconductor wafer W to the predetermined thickness.

[0095] 4C , in the mounting step, a dicing ring R is attached to the adhesive fixing layer 22 of the dicing tape 20, and the semiconductor wafer W is attached and fixed to the adhesive fixing layer 22 of the dicing tape 20. If the grinding step is not performed, the attachment step of the temporary protection step may be performed by attaching and fixing the semiconductor wafer W to the adhesive fixing layer 22 of the dicing tape 20, and then overlaying the protective layer 12 on the surface to be protected (circuit surface) of the semiconductor wafer W.

[0096] 4D , for example, the peeling step of the removal process involves peeling the base material layer 11 from the surface of the protective layer 12 before removing the protective layer 12 from the surface of the semiconductor wafer W. In the peeling step, the protective layer 12 may be irradiated with active energy rays such as ultraviolet rays before peeling the base material layer 11. In this case, the protective layer 12 includes a photopolymerization initiator or the like as described above.

[0097] After the peeling step, a dicing step is carried out as necessary to diced at least the protective layer 12. For example, the protective layer 12 and the semiconductor wafer W may be diced into semiconductor chips (dies) by laser grouping and plasma dicing of the semiconductor wafer W.

[0098] In the dicing step, only the protective layer 12 or both the protective layer 12 and the semiconductor wafer W are diced, as shown in Fig. 4E or 4F. In the laser grouping process, as shown in Fig. 4E, the circuit surface is protected by the protective layer 12 while being irradiated with laser light L. For example, a SiO ２ Laser grouping can be performed when an insulating film called a low-k film, which has a dielectric constant lower than that of the semiconductor wafer W, is present on the circuit surface. The wiring layer containing the low-k film is removed with laser light, forming two narrow grooves spaced apart within the dicing street. The semiconductor wafer W can then be divided into smaller pieces by a subsequent plasma dicing process. During laser grouping, foreign matter such as fragments of the insulating film may be generated by the irradiation of the laser light L. Since the surface of the semiconductor wafer W to be protected is protected by the protective layer 12, adhesion of foreign matter to the surface to be protected can be suppressed.

[0099] In plasma dicing, a semiconductor wafer W is cut to a predetermined size to form semiconductor chips, as shown in FIG. 4F. By forming two grooves as described above, plasma can be applied only to the area between the two grooves. Plasma dicing is performed in a conventional manner using, for example, a plasma generator.

[0100] In the dicing process, for example, as shown in FIG. 4G , while the semiconductor wafer W with the protective layer 12 attached thereto is fixed on the adhesive fixing layer 22 of the dicing tape 20, an expanding operation may be performed to stretch the dicing tape 20 in the planar direction to increase the surface area of ​​the dicing tape 20. This divides the stack of the semiconductor wafer W and the protective layer 12 into small pieces, and further increases the spacing between adjacent semiconductor chips X formed by the dicing in the planar direction. The semiconductor wafer W needs to be diced by the expanding operation. Therefore, the semiconductor wafer W diced as described above is designed to be easily cleaved. For example, a fragile portion is formed inside the semiconductor wafer W for dicing into semiconductor chips X (dies). The fragile portion can be formed by irradiating the semiconductor wafer W with laser light using a commercially available stealth dicing device. The protective layer 12 also needs to be diced by the expanding operation, and is therefore designed to be easily cleaved.

[0101] Details of the above-described expanding operation are as follows. For example, as shown in FIG. 4G , a dicing ring R is attached to the adhesive fixing layer 22 of the dicing tape 20, and then the dicing ring R is fixed to a holder H of an expanding device. A push-up member U provided in the expanding device is pushed up from below the dicing tape 20, stretching the dicing tape 20 so as to expand it in the surface direction. This causes the semiconductor wafer W and the protective layer 12 to be broken into small pieces under specific temperature conditions. The temperature conditions are, for example, −20° C. or higher and 0° C. or lower. The expanded state is released by lowering the push-up member U (this is the low-temperature expanding operation). Furthermore, under higher temperature conditions (for example, 10° C. or higher and 25° C. or lower), the dicing tape 20 is stretched so as to expand its surface area. This separates adjacent semiconductor chips X in the surface direction of the dicing tape 20, further widening the kerf (gap) (room-temperature expanding operation). By stretching the dicing tape 20 in the planar direction so as to increase the area of ​​the dicing tape 20, the semiconductor wafer W can be divided into small semiconductor chips X along the boundaries of the weak portions inside the semiconductor wafer. At this time, the semiconductor wafer W is divided into small semiconductor chips X, and the protective layer 12 is also divided into small pieces.

[0102] In the dissolving step of the removal process, as shown in Figures 4H and 4I, the protective layer fragments 12' are brought into contact with a liquid containing water, and at least a portion of each of the fragments 12' is dissolved by the liquid, thereby removing each of the protective layer fragments 12' from the surface (surface to be protected) of the semiconductor wafer W or semiconductor chip X. By removing the protective layer fragments 12' in this manner, all of the protective layer fragments 12' can be removed relatively easily, and the number of foreign substances attached to the surface to be protected can be relatively easily reduced by the liquid. Furthermore, the surface (surface to be protected) of the semiconductor wafer W on which the protective layer 12 was overlaid, or the surface (surface to be protected) of each semiconductor chip X on which the protective layer fragments 12' were overlaid, can also be washed with a liquid.

[0103] In the dissolving step of the removal process, at least a portion of the fragmented protective layer (the plurality of small pieces 12' of the protective layer) is dissolved by the liquid. As a result, the adhesive strength of the small pieces 12' of the protective layer to the semiconductor chip X weakens, and the small pieces 12' of the protective layer become more easily peeled off from the semiconductor chip X. This allows the plurality of small pieces 12' of the protective layer to be removed relatively easily.

[0104] The water-containing liquid 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 of water. The liquid may contain a component that dissolves in water in addition to water. Examples of such a component include water-soluble organic solvents. Examples of such water-soluble organic solvents include monohydric alcohols having 4 or less carbon atoms, such as methanol, ethanol, propanols such as isopropyl alcohol, and butanols such as t-butanol.

[0105] In the dissolving 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 may be sprayed from a nozzle or the like to bring the protective layer pieces 12' into contact with the liquid. 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.

[0106] For example, in the dissolving step of the removal process, the liquid is sprayed toward the semiconductor wafer W attached to the dicing tape 20 or the semiconductor chip X attached to the dicing tape 20 while rotating a disk-shaped stage supporting the dicing tape 20 from below in the circumferential direction. This makes it possible to remove a plurality of small pieces 12' of the protective layer overlapping the semiconductor wafer W or the semiconductor chip X, respectively. The rotation speed of the stage may be, for example, 500 rpm or more and 4000 rpm or less, the spray amount of the liquid may be, for example, 0.05 L / min or more and 5.0 L / min or less, and the spray time may be, for example, 5 seconds or more and 300 seconds or less.

[0107] According to the semiconductor device manufacturing method of the above embodiment, the protective layer 12 is superimposed on the surface (circuit surface) of the semiconductor wafer W on which the circuit components are formed, so that the circuit surface can be protected until the protective layer 12 is removed. Even if foreign matter is attached to the circuit surface before the protective layer 12 is superimposed, the foreign matter can be removed when the small pieces 12' of the protective layer superimposed on the circuit surface are removed. Therefore, it is possible to prevent foreign matter from adhering to the circuit surface of the semiconductor chip X to be manufactured.

[0108] In the removal step, the semiconductor wafer W or semiconductor chip X is peeled off from the adhesive fixing layer 22 of the dicing tape 20. During the removal step, the semiconductor wafer W or semiconductor chip X needs to be easily peeled off from 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 so that the adhesive fixing layer 22 hardens and the adhesive strength of the adhesive fixing layer 22 decreases when irradiated with active energy rays (e.g., ultraviolet rays). The adhesive strength of the adhesive fixing layer 22 can be reduced by hardening the adhesive fixing layer 22 after irradiation, so that the semiconductor wafer W or semiconductor chip X can be relatively easily peeled off from the adhesive fixing layer 22 after irradiation. Dicing tapes 20 configured in this manner are commercially available.

[0109] Although the protective sheet and the method for manufacturing an electronic component device according to the embodiment of the present invention are as exemplified above, the present invention is not limited to the protective sheet or the method for manufacturing an electronic component device exemplified above. In other words, various forms used in general protective sheets or methods for manufacturing electronic component devices can be adopted as long as they do not impair the effects of the present invention.

[0110] The present specification discloses the following: (1) A protective sheet comprising a protective layer to be bonded to a surface of a substrate to be protected, the protective layer containing a water-soluble compound, and the adhesive strength of the protective layer to a silicon wafer being 0.5 N / 10 mm or more. A protective sheet having the above configuration has good embedding properties of the protective layer, good peel resistance of the protective layer bonded to the surface of the substrate to be protected, and the protective layer is easily removed by a liquid containing water. (2) The protective sheet according to (1) above, wherein the protective layer has a storage modulus at 70°C of 50,000 Pa or less. (3) The protective sheet according to (1) or (2) above, wherein the protective layer contains a first water-soluble compound and a second water-soluble compound as the water-soluble compounds, the first water-soluble compound is a compound having a polyoxyethylene structure in its molecule, and the second water-soluble compound is a water-soluble polyester resin having a mass-average molecular weight of 2,000 or more. (4) A method for manufacturing an electronic component device, comprising a temporary protection step of protecting a surface of a substrate to be protected with a protective sheet and then removing the protective sheet, wherein the protective sheet comprises a protective layer containing a water-soluble polymer compound and a base layer overlying one side of the protective layer, and the adhesive strength of the protective layer to a silicon wafer is 0.5 N / 10 mm or more, the temporary protection step comprising a first step of bonding the protective layer of the protective sheet to the surface to be protected and a second step of removing the protective sheet from the surface to be protected, the second step comprising a step of peeling the base layer from the protective layer and a step of removing the protective layer by dissolving at least a portion of the protective layer with a liquid containing water. In this method for manufacturing an electronic component device, the use of the protective sheet provides good embedding of the protective layer, good peel resistance of the protective layer bonded to the surface to be protected of the substrate, and the protective sheet is easily removed with a liquid containing water.

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

[0112] Each protective sheet (protective layer) of the Examples and Comparative Examples was prepared as follows.

[0113] [Examples 1 to 3, Comparative Examples 1 to 3] <Raw materials for forming protective layer> (First water-soluble compound) P1-A Random copolymer of ethylene oxide and propylene oxide Product name "ALKOX EP1010N" (manufactured by Meisei Chemical Industry Co., Ltd.) Mass average molecular weight: about 100,000 P1-B Homopolymer of ethylene oxide Product name "ALKOX R-150" (manufactured by Meisei Chemical Industry Co., Ltd.) Mass average molecular weight: about 100,000 P1-C Polyethylene glycol (purchased as a reagent) Average molecular weight: about 2,000 P1-D Polyethylene glycol (purchased as a reagent) Average molecular weight: about 600 (Second water-soluble compound) P2-A Water-soluble polyester resin Product name "PLASCOAT Z-221" (manufactured by GOO Chemical Industry Co., Ltd.) Having a sulfo group in the molecule Mass average molecular weight: about 14,000 (Other water-soluble compounds) PVA Polyvinyl alcohol Product name: "JMR-3M" (manufactured by Nippon Vinyl Acetate & Poval Co., Ltd.) Mass average molecular weight: approximately 10,000

[0114] (Preparation of Protective Sheets) Protective sheets were prepared according to the compositions shown in Table 1. Specifically, an aqueous solution of each polymer was prepared so that the total polymer concentration was 20% by mass using the blending composition shown in Table 1. When preparing the aqueous solution of each polymer, the solution was heated to 60°C. The aqueous solution of each polymer was applied to release liner a (PET film, 50 μm thick). Release liner a had a surface that had been treated with a silicone release agent, and the aqueous solution of the polymer was applied to this surface using an applicator. Next, a drying treatment was performed at 130°C for 2 minutes to form a protective layer with a thickness of 5 μm superimposed on one surface of release liner a. Thereafter, release liner b (PET film, 25 μm thick) was superimposed on the exposed surface of each protective layer. Note that release liner b had a surface that had been treated with a silicone release agent, and this surface was attached to the protective layer. In this manner, protective sheets comprising a protective layer sandwiched between two release liners were prepared.

[0115] (Shear storage modulus of protective layer) The shear storage modulus of each protective layer was measured according to the method described above. The results are shown in Table 1.

[0116] (Peeling Force of Protective Layer from Bare Silicon Wafer) The peeling force of each protective layer from a bare silicon wafer was measured according to the method described above. The results are shown in Table 1.

[0117]

[0118] <Evaluation of Embeddability> The embeddability of each protective sheet in a semiconductor chip having multiple bump electrodes on one surface (hereinafter referred to as a semiconductor chip with bump electrodes) was evaluated. First, protective sheets of each Example and Comparative Example were prepared with a release liner attached to only one surface. Next, semiconductor chips with bump electrodes were fabricated as follows. Specifically, multiple regions (3 mm × 3 mm regions) in which multiple bump electrodes were arranged were formed on one surface of a semiconductor wafer body. In these regions, the diameter (bump diameter) of the bump electrodes was 45 μm, the spacing between adjacent bump electrodes (bump pitch) was 150 μm, and the height from the surface of the semiconductor wafer body on the semiconductor wafer to the tip of the bump electrode was 40 μm. The semiconductor wafer was cut to a planar dimension of 5 mm × 5 mm so that each semiconductor chip with bump electrodes had one of the multiple regions. Next, the protective layer of each protective sheet was applied to one side of the semiconductor wafer body under conditions of a pressure (laminating pressure) of 0.4 MPa and a roller temperature of 60°C. Then, by observation with a digital microscope, the embeddability was evaluated according to the following criteria. The results are shown in Table 1 below. (Evaluation criteria) Excellent: No optical interference was observed. That is, the entire bump electrode was sufficiently embedded inside the protective layer. Good: Some optical interference was observed in the outer periphery of each bump electrode. That is, although the vicinity of the top of each bump electrode was sufficiently embedded inside the protective layer, the outer periphery of each bump electrode was not sufficiently embedded. Poor: Clear voids were observed in the outer periphery of each bump electrode. That is, even the vicinity of the top of each bump electrode was not sufficiently embedded inside the protective layer.

[0119] As can be seen from the above evaluation results, the protective layer of the example had good embedding properties for the adherend (substrate) having an uneven surface. Although not shown in the above results, in the removal process, the base layer could be peeled off from the protective layer attached to the bare silicon wafer without the protective layer. Furthermore, the multiple small pieces of the protective layer could be removed relatively easily with water.

[0120] By manufacturing a semiconductor device or the like using the protective layer of the above-described embodiment, it is possible to efficiently manufacture a semiconductor device or the like that includes a semiconductor chip with almost no foreign matter adhering thereto.

[0121] The method for manufacturing an electronic component device of the present invention is suitably used for manufacturing a semiconductor device having, for example, a semiconductor integrated circuit.

[0122] 1: Protective sheet, 11: Base material layer, 11a: Support layer, 11b: Adhesive layer, 12: Protective layer, 12': Small piece of protective layer, 15: Release liner, 20: Dicing tape, 21: Underlayer, 22: Adhesive fixing layer, W: Semiconductor wafer, X: Semiconductor chip.

Claims

1. A protective sheet comprising a protective layer to be attached to a surface of a substrate to be protected, the protective layer containing a water-soluble compound, and the adhesive strength of the protective layer to a silicon wafer being 0.5 N / 10 mm or more.

2. The protective sheet according to claim 1, wherein the protective layer has a storage modulus at 70° C. of 50,000 Pa or less.

3. The protective sheet according to claim 1 or 2, wherein the protective layer comprises a first water-soluble compound and a second water-soluble compound as the water-soluble compounds, the first water-soluble compound is a compound having a polyoxyethylene structure in the molecule, and the second water-soluble compound is a water-soluble polyester resin having a mass average molecular weight of 2,000 or more.

4. A method for manufacturing an electronic component device, comprising a temporary protection step of protecting a surface of a substrate to be protected with a protective sheet and then removing the protective sheet, wherein the protective sheet comprises a protective layer containing a water-soluble polymer compound and a base layer overlapping one side of the protective layer, and the adhesive strength of the protective layer to a silicon wafer is 0.5 N / 10 mm or more, the temporary protection step comprising a first step of bonding the protective layer of the protective sheet to the surface to be protected and a second step of removing the protective sheet from the surface to be protected, and the second step comprising a step of peeling the base layer from the protective layer and a step of removing the protective layer by dissolving at least a portion of the protective layer with a liquid containing water.

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