Protective sheet

Abstract

Provided is a protective sheet which is provided with a protective layer that is removed by a liquid that contains water after protecting at least a part of the surface of an object to be protected, and which contains a solid hydrophilic polymer and a liquid compound that contains a hydrophilic group in the molecule.

Description

Technical Field

[0001] This application claims the priority of Japanese Patent Application No. 2022-111735, which is incorporated by reference into the description of the present application specification.

[0002] The present invention relates to, for example, a protective sheet used in manufacturing electronic devices such as semiconductor integrated circuits. Background Art

[0003] In the past, there is known a protective sheet for protecting at least a portion of the surface of a protected object, for example, in the manufacture of a semiconductor device. The protected object of such a protective sheet is, for example, a substrate such as a semiconductor wafer. Such a protective sheet is used by being attached to at least a portion of the surface of the protected object in the manufacturing process of the semiconductor device.

[0004] Generally, the method for manufacturing a semiconductor device comprises: a front process of forming a circuit surface on one side of a disc-shaped bare wafer by a highly integrated electronic circuit; and a back process of cutting out semiconductor chips from the semiconductor wafer with the circuit surface formed thereon for assembly. In the back process, in addition to using a dicing tape having a base layer and an adhesive layer and a chip bonding sheet laminated on the dicing tape and bonded to the semiconductor wafer, the above-mentioned protective sheet is also used.

[0005] In detail, the post-process includes: a protection process, in which the circuit surface of the disc-shaped semiconductor wafer is protected by covering it with a protection sheet as described above; a fixing process, in which the surface of the semiconductor wafer (the surface without the circuit components) is superimposed on the chip bonding sheet on the dicing tape, and the semiconductor wafer is fixed to the dicing tape via the chip bonding sheet; a dicing process, in which a plurality of semiconductor chips (dies) are obtained by dicing the semiconductor wafer and the chip bonding sheet; an expansion process, in which the dicing tape is stretched in the radial direction of the semiconductor wafer to expand the interval between adjacent semiconductor chips (dies); a picking process, in which the dicing tape is peeled off from the dicing tape to take out the semiconductor chip with the dicing sheet attached; a chip bonding process, in which the semiconductor chip with the dicing sheet attached is bonded to the adherend via the dicing sheet; and a curing process, in which the dicing sheet bonded to the adherend is thermally cured. A semiconductor device is manufactured, for example, through these processes.

[0006] As the above-mentioned protective sheet, for example, the following protective sheet is known: in order to prevent the deposited material from adhering to the surface (protected surface) of the semiconductor wafer etc. in the film forming process by vapor deposition etc., it is removed after being attached to the protected surface (for example, Patent Document 1).

[0007] The protective sheet described in Patent Document 1 has a resin composition containing a polyvinyl alcohol-based resin containing an oxyalkylene group with a saponification degree of 55 mol% or less. The resin composition of the protective sheet described in Patent Document 1 is water-soluble and can be easily removed by relatively low-temperature water after protecting a portion of the surface of a substrate such as a semiconductor wafer. In addition, the resin composition of the protective sheet described in Patent Document 1 can appropriately adhere to the protected surface because it contains the above-mentioned polyvinyl alcohol-based resin.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2021-161735 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, although the resin composition of the protective sheet described in Patent Document 1 can be appropriately adhered to the protected object, it has a problem that the processability is not necessarily good because it contains only polyvinyl alcohol-based resin and additives, etc. Specifically, when the resin composition formed into a sheet is cut into a protective layer of a desired size, micro cracks are easily generated in the portion of the protective layer subjected to the cutting force, and the processability is not necessarily good.

[0013] As described above, the protective layer formed of the resin composition of the protective sheet described in Patent Document 1 can be removed relatively easily by a liquid containing water and has appropriate adhesion to the object to be protected, but has a problem that the processability is not necessarily good.

[0014] On the other hand, it cannot be said that sufficient research has been conducted on a protective sheet having a protective layer that can be relatively easily removed by a liquid containing water and has good adhesion to a protected object and good processability.

[0015] Therefore, an object of the present invention is to provide a protective sheet including a protective layer that can be relatively easily removed by a liquid containing water, has good adhesion to a protected object, and has good processability.

[0016] Solutions for solving problems

[0017] To solve the above problems, the protective sheet of the present invention comprises: a protective layer which protects at least a part of the surface of the object to be protected and is then removed by a liquid containing water, the protective layer comprising a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in its molecule. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is a schematic cross-sectional view of an example of the protective sheet according to the present embodiment cut in the thickness direction.

[0019] Figure 2A This is a schematic cross-sectional view showing an example of a wetting step in a method for manufacturing an electronic device.

[0020] Figure 2B This is a schematic cross-sectional view showing an example of a protection step in a method for manufacturing an electronic device.

[0021] Figure 2C This is a schematic cross-sectional view showing an example of a state after a protection step in a method of manufacturing an electronic device.

[0022] Figure 2D This is a schematic cross-sectional view showing an example of a removal step in a method for manufacturing an electronic device (a schematic cross-sectional view showing an example of a protective layer being removed from a protected surface of an object to be protected by a liquid containing water).

[0023] Figure 3A This is a cross-sectional view of an example of a dicing tape cut in the thickness direction.

[0024] Figure 3B This is a cross-sectional view of an example of a dicing die bonding film cut in the thickness direction.

[0025] Figure 4A It is a schematic cross-sectional view showing a state after the fixing step and the protecting step in the method for manufacturing the semiconductor device according to the first example are performed.

[0026] Figure 4B It is a schematic cross-sectional view showing a situation in the middle of a blade dicing process in the method for manufacturing a semiconductor device according to the first example.

[0027] Figure 4C This is a schematic cross-sectional view showing a state after the blade dicing process in the method for manufacturing a semiconductor device according to the first example is performed.

[0028] Figure 4D It is a schematic cross-sectional view showing a state of a removal step in the method for manufacturing a semiconductor device according to the first example.

[0029] Figure 4E It is a schematic cross-sectional view showing a state of a pickup step in the method for manufacturing a semiconductor device according to the first example.

[0030] Figure 4F It is a schematic cross-sectional view showing a bonding step in the method for manufacturing a semiconductor device according to the first example.

[0031] Figure 5AIt is a schematic cross-sectional view showing a state after the half-cutting process of the semiconductor wafer in the method for manufacturing a semiconductor device according to the second example.

[0032] Figure 5B It is a schematic cross-sectional view showing a state after backside grinding in the method for manufacturing a semiconductor device according to the second example.

[0033] Figure 5C It is a schematic cross-sectional view showing a state of a fixing step in a method for manufacturing a semiconductor device according to a second example.

[0034] Figure 5D It is a schematic cross-sectional view showing a state of an expansion step in a method for manufacturing a semiconductor device according to a second example.

[0035] Figure 5E It is a schematic cross-sectional view showing a modified example of a state after the half-cutting process of the semiconductor wafer in the method for manufacturing a semiconductor device according to the second example.

[0036] Fig. 5F It is a schematic cross-sectional view showing a modified example of the state after the back surface grinding process in the method for manufacturing a semiconductor device of the second example.

[0037] Figure 5G It is a schematic cross-sectional view showing a modification of the fixing step in the method for manufacturing a semiconductor device according to the second example.

[0038] Fig. 6A It is a schematic cross-sectional view showing a situation in a stealth processing step in a method for manufacturing a semiconductor device according to a third example.

[0039] Figure 6B It is a schematic cross-sectional view showing a state after a stealth processing step in the method for manufacturing a semiconductor device according to the third example.

[0040] Figure 6C It is a schematic cross-sectional view showing a state of an expansion step in a method for manufacturing a semiconductor device according to a third example.

[0041] Fig.6D It is a schematic cross-sectional view showing a state of a removal step in the method for manufacturing a semiconductor device according to the third example.

[0042] Fig. 6E It is a schematic cross-sectional view showing a modification of the state before backside grinding in the method for manufacturing a semiconductor device according to the third example.

[0043] Fig. 6F It is a schematic cross-sectional view showing a modified example of the state after the back surface grinding process in the method for manufacturing a semiconductor device according to the third example.

[0044] Figure 6GIt is a schematic cross-sectional view showing a modification of the fixing step in the method for manufacturing a semiconductor device according to the third example. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the protective sheet of the present invention will be described with reference to the accompanying drawings. It should be noted that each of the drawings is a schematic diagram, and therefore the length ratio between the drawings and the actual object is not necessarily the same.

[0046] like Figure 1 As shown, the protective sheet 1 of this embodiment includes a protective layer 11, which protects at least a portion of the surface of the protected object, and at least a portion of the protective layer 11 is dissolved and removed from the surface of the protected object when in contact with a liquid containing water. In addition, the protective layer 11 includes a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in the molecule.

[0047] With the above-described configuration, the protective layer 11 of the protective sheet 1 of the present embodiment can be removed relatively easily by a liquid containing water, and has excellent adhesion to the object to be protected and excellent processability.

[0048] [Release liner of protective sheet]

[0049] The protective sheet 1 may be, for example, Figure 1 As shown, two release liners 15 are provided so as to sandwich the protective layer 11. The surface of the release liner 15 in contact with the protective layer 11 may be subjected to release treatment.

[0050] The release liner 15 may be, for example, a resin film. Examples of the resin film include a polyethylene terephthalate resin film, a polyethylene film, and a polypropylene film.

[0051] [Protective layer of protective sheet]

[0052] The protective layer 11 is used, for example, to temporarily protect a protected surface of an object to be protected (hereinafter, also referred to as a protected surface). By overlapping the protective layer 11 on the protected surface, foreign matter can be prevented from adhering to the protected surface until the protective layer 11 overlapping the protected surface is removed.

[0053] Examples of the object to be protected include substrates constituting electronic devices such as semiconductor devices, etc. Examples of the substrate include circuit boards such as semiconductor wafers W, etc.

[0054] For example, when the protective layer 11 is adhered to the protected surface (circuit surface) of the substrate (semiconductor chip) and is cut into small pieces together with the substrate (semiconductor chip), it can prevent foreign matter such as fragments that may be generated by the small pieces from adhering to the protected surface (circuit surface), thereby protecting the protected surface (circuit surface).

[0055] The protective layer 11 has flexibility that allows it to be deformed by a relatively weak force. In addition, the protective layer 11 has adhesion that allows it to be closely attached to the protected surface of the substrate, for example.

[0056] The protective layer 11 may have a property of being cut into small pieces by being stretched in the plane direction. The protective layer 11 having the above-mentioned properties is preferably used in the case where an electronic device is manufactured through a stealth processing step using a stealth cutting device described later. Similarly, it is preferably used in the case where an electronic device is manufactured through a DBG process (described in detail later).

[0057] It should be noted that the protective layer 11 described above can also be preferably used in the case of manufacturing an electronic device through a blade dicing process (described in detail later), and therefore it is not necessary to have the above-mentioned physical properties.

[0058] In the above-mentioned protective sheet 1, the thickness of the protective layer 11 is not particularly limited, for example, it is 1 μm or more and 100 μm or less. The above-mentioned thickness can be 3 μm or more, or 5 μm or more. In addition, the above-mentioned thickness can be 40 μm or less. It should be noted that, when the protective layer 11 is a laminate, the above-mentioned thickness is the total thickness of the laminate.

[0059] In the present embodiment, the hydrophilic polymer contained in the protective layer 11 is solid at room temperature.

[0060] On the other hand, the liquid compound containing a hydrophilic group in its molecule contained in the protective layer 11 is liquid at room temperature. Hereinafter, the liquid compound containing a hydrophilic group in its molecule may be simply referred to as a "liquid component".

[0061] The state (solid or liquid) at room temperature is determined as follows. Specifically, if the viscosity at 25°C is 200 [Pas·s] or less (200,000 [mPas·s] or less), it is determined to be a liquid component, and if it is not a liquid, it is determined to be a solid. The viscosity is measured using an E-type viscometer (e.g., manufactured by Toki Sangyo Co., Ltd., product name "TV-35") under the measurement conditions of 25°C and 20 rpm.

[0062] It should be noted that, when confirming the properties (solid or liquid) of each component contained in the above-mentioned protective layer 11, a trace amount of each compounding component can be extracted from the protective layer 11, and the molecular structure of each compounding component can be investigated, for example, by infrared absorption spectroscopy (IR). If the compounding component is a polymer compound, the molecular weight of the polymer compound can be further investigated by gel permeation chromatography (GPC). In addition, the properties (solid or liquid) of each component can be confirmed by purchasing a compound specified by these analytical methods and measuring the viscosity as described above.

[0063] The hydrophilic polymer has a hydrophilic group in its molecule. The hydrophilic group of the hydrophilic polymer may be, for example, at least one selected from the group consisting of a hydroxyl group, a carboxyl group (including a salt), a sulfonic acid group (including a salt), a pyrrolidone group, an amine-containing group (including a quaternary ammonium cation), and a polyoxyethylene group.

[0064] When the hydrophilic polymer contains a hydroxyl group as a hydrophilic group in the molecule, the protective layer 11 can more fully adhere to the protected surface of the object to be protected.

[0065] For example, the protective layer 11 includes a hydrophilic polymer having a main chain and a plurality of side chains in the molecule as the hydrophilic polymer, each of the plurality of side chains has at least one of an ester group and a hydrophilic group, and the hydrophilic group may be a hydroxyl group or a carboxyl group.

[0066] The main chain of the hydrophilic polymer is, for example, a covalent chain generated by a free radical polymerization reaction. For example, the main chain is a covalent chain generated by a polymerization reaction of vinyl acetate, (meth)acrylic acid alkylester, (meth)acrylic acid hydroxyalkyl ester, (meth)acrylic acid, or N-vinyl pyrrolidone.

[0067] Each of the plurality of side chains in the above-mentioned hydrophilic polymer contains at least one of a hydrophilic group and an ester group. For example, among the many side chains contained in the above-mentioned hydrophilic polymer, a part of the side chains have a hydrophilic group, and another part has an ester group. The hydrophilic group is, for example, at least one of a hydroxyl group or a carboxyl group. The ester group is represented by -C(=O)-O-. The side chain may have an atomic sequence of an ester group such as -C(=O)-O- from the main chain toward the end of the side chain, or may have an atomic sequence of an ester group such as -O-(C=O)-.

[0068] In each side chain containing a hydrophilic group, the hydrophilic group may be arranged at the end portion of the side chain or at the central portion of the side chain. The hydrophilic group of the side chain is preferably arranged at the end portion of the side chain. It should be noted that the hydrophilic group arranged at the end portion of the side chain may be bonded to the main chain via an ester group. For example, from the main chain toward the end of the side chain, each group may be arranged in the order of an ester group, an alkyl group, and a hydrophilic group.

[0069] In the side chain including an ester group, the ester group is preferably arranged in the center of the side chain. In the side chain, preferably, an alkyl group having 1 to 4 carbon atoms is bonded to the main chain via the ester group.

[0070] Examples of the hydrophilic polymer include polyvinyl alcohol (PVA) obtained by hydrolyzing a portion of the ester bonds in a vinyl acetate polymer, polyvinyl pyrrolidone (PVP), a water-soluble polyester polymer (PES) having a sulfonic acid group or a carboxyl group in the molecule, polyoxyethylene (PEO) (e.g., having a molecular weight of 50,000 or more), polyacrylic acid, or polyvinyl acetamide.

[0071] The hydrophilic polymer is preferably water-soluble. The water-solubility of the hydrophilic polymer can be confirmed, for example, as follows. When a thin film of the hydrophilic polymer (thickness 50 μm or less) is attached to a bare silicon wafer and immersed in water at 25° C. or 60° C., the hydrophilic polymer is water-soluble when the thin film is completely dissolved (no residue remains on the wafer) at at least one temperature.

[0072] The hydrophilic polymer is preferably at least one selected from the group consisting of polyvinyl alcohol, a water-soluble polyester polymer, and polyoxyethylene.

[0073] When the hydrophilic polymer is polyvinyl alcohol (PVA), the saponification degree (mol %) of the polyvinyl alcohol may be 50 or more and 100 or less.

[0074] The saponification degree of polyvinyl alcohol is preferably 55 or more, more preferably 60 or more, and further preferably 65 or more. As the saponification degree of polyvinyl alcohol increases, the protective layer 11 has higher hydrophilicity. Therefore, the protective layer 11 can be removed more easily with a liquid containing water.

[0075] On the other hand, the degree of saponification of the polyvinyl alcohol is preferably 98 or less, more preferably 90 or less, and even more preferably 85 or less, from the viewpoint of further improving the adhesion to the object to be protected, such as a substrate.

[0076] <Saponification degree measurement method and measurement conditions>

[0077] The above saponification degree was determined by proton nuclear magnetic resonance spectroscopy under the following analytical conditions: 1 HNMR).

[0078] In addition, when the protective layer 11 contains a component other than PVA, in order to avoid overlapping peaks in the measurement chart, the measurement is performed after separation and extraction treatment of PVA by methanol extraction or the like.

[0079] Analytical apparatus: FT-NMR.

[0080] (For example, "AVANCEIII-400" manufactured by Bruker Biospin.)

[0081] Observation frequency: 400MHz(1H).

[0082] Determination solvent: heavy water or heavy dimethyl sulfoxide (heavy DMSO).

[0083] Measurement temperature: 80℃.

[0084] Chemical shift standard: external standard TSP-d4 (0.00 ppm) (when measuring with heavy water).

[0085] : Measurement solvent (2.50 ppm) (in case of heavy DMSO measurement).

[0086] <Calculation of Saponification Degree>

[0087] The saponification degree was calculated by the following formula based on the peak derived from the methylene group of the vinyl alcohol unit (VOH) (heavy water: 2.0 to 1.1 ppm, heavy DMSO: 1.9 to 1.0 ppm) and the peak derived from the acetyl group of the vinyl acetate unit (VAc) (heavy water: around 2.1 ppm, heavy DMSO: around 2.0 ppm). 2 -) is the intensity of the peak derived from the methylene group of the vinyl alcohol unit (VOH), VAc (CH 3 CO-) is the intensity of the peak derived from the acetyl group of the vinyl acetate unit (VAc).

[0088]

[0089] The average degree of polymerization of the polyvinyl alcohol is preferably 100 or more, more preferably 200 or more. Furthermore, the average degree of polymerization is preferably 1200 or less, more preferably 1000 or less, and further preferably 800 or less.

[0090] When the average degree of polymerization of polyvinyl alcohol is 100 or more, the protective layer 11 can be formed more easily. That is, the processability of the protective layer 11 can be improved. On the other hand, when the average degree of polymerization of polyvinyl alcohol is 1200 or less, the hydrophilicity of polyvinyl alcohol is further improved, and the protective layer 11 can be dissolved more easily in a liquid containing water. In addition, the adhesion of the protective layer 11 to the object to be protected can be improved.

[0091] The above-mentioned average degree of polymerization is determined by the following measurement method and measurement conditions.

[0092] <Method and conditions for measuring average degree of polymerization>

[0093] ·Analysis device: Gel permeation chromatography analysis device.

[0094] (For example, the device is manufactured by Agilent and is called "1260 Infinity".)

[0095] Chromatographic columns: TSKgel G6000PWXL and TSKgel G3000PWXL (manufactured by Tosoh Corporation, connected in series).

[0096] Column temperature: 40°C.

[0097] Eluent: 0.2 M sodium nitrate aqueous solution.

[0098] Flow rate: 0.8 mL / min.

[0099] Injection volume: 100 μL.

[0100] · Detector: Differential Refractometer (RI).

[0101] Standard samples: PEG standard samples and PVA standard samples.

[0102] By using the GPC measurement of the PEG standard sample, the mass average molecular weight Mw of the measured sample (PVA) and the PVA standard sample with a known average polymerization degree are calculated respectively. A standard curve is prepared according to the average polymerization degree of the PVA standard sample and the calculated mass average molecular weight Mw of the PVA standard sample. Using this standard curve, the average polymerization degree of the measured sample (PVA) is obtained according to the mass average molecular weight Mw of the measured sample (PVA).

[0103] The above-mentioned water-soluble polyester polymer (PES) has a residue of a polycarboxylic acid and a residue of a polyol. The above-mentioned water-soluble polyester is, for example, a polymerization product of monomer components containing a polycarboxylic acid component and a polyol component. The molecules of the above-mentioned water-soluble polyester polymer may also have at least one of anionic hydrophilic groups, cationic hydrophilic groups, or nonionic hydrophilic groups. As anionic hydrophilic groups, for example, sulfonic acid groups (including salt states), carboxyl groups (including salt states), etc. can be listed. As cationic hydrophilic groups, for example, amine-containing groups can be listed. As nonionic hydrophilic groups, for example, polyoxyethylene groups can be listed. It should be noted that the water-soluble nature of the water-soluble polyester can be judged based on technical common sense.

[0104] The mass average molecular weight Mw of the water-soluble polyester polymer (PES) is preferably 40,000 (40,000) or less. When the mass average molecular weight Mw is 40,000 or less, the water-soluble polyester polymer can have a sufficiently low softening point. As a result, the adhesion of the protective layer 11 to the substrate (semiconductor wafer, etc.) can be improved. In addition, the protective layer 11 can be more easily removed from the surface of the protected object by a liquid containing water.

[0105] The above-mentioned polyoxyethylene (PEO) has polyoxyethylene groups as hydrophilic groups in its molecules. The mass average molecular weight Mw of the above-mentioned polyoxyethylene (PEO) is preferably below 1,000,000 (1,000,000). By having a mass average molecular weight Mw of below 1,000,000, the above-mentioned polyoxyethylene (PEO) can have a sufficiently low softening point. Thus, the adhesion of the protective layer 11 to the substrate (semiconductor wafer, etc.) can become better. In addition, the protective layer 11 can be efficiently removed from the surface of the protected object in a shorter time by a liquid containing water.

[0106] The polyacrylic acid has a carboxyl group as a hydrophilic group in the molecule. The polyacrylic acid is a polymer obtained by polymerizing an acrylic acid monomer or a methacrylic acid monomer. In the polyacrylic acid, the total mass ratio of the structural unit of the acrylic acid monomer or the structural unit of the methacrylic acid monomer to the total structural unit is 90 mass % or more.

[0107] The molecular weight of the polyacrylic acid may be, for example, 1,000 or more and 5,000,000 or less.

[0108] It should be noted that the above-mentioned polyacrylic acid may be in the form of a salt such as a sodium salt, a potassium salt, or an ammonium salt. In other words, the above-mentioned expression "polyacrylic acid" includes polyacrylates such as sodium polyacrylate.

[0109] The polyvinyl acetamide has an amine-containing group as a hydrophilic group in the molecule. Specifically, the amine-containing group is represented by (-NH-CO-). The polyvinyl acetamide is a polymer of N-vinylacetamide monomer.

[0110] In the present embodiment, the liquid component is a liquid compound containing a hydrophilic group in the molecule. Examples of the hydrophilic group of the liquid component include a hydroxyl group, a carboxyl group (including a salt), a sulfonic acid group (including a salt), a pyrrolidone group, an amine-containing group (including a quaternary ammonium cation), or a polyoxyethylene group.

[0111] The above-mentioned liquid component may be a low molecular compound or a high molecular compound if it is liquid at room temperature (25°C). Examples of the above-mentioned liquid component include polyethylene glycol that is liquid at room temperature, acrylic copolymer that is liquid at room temperature, ether-containing compounds that are liquid at room temperature, polyoxyethylene polyoxypropylene glycol that is liquid at room temperature, polycationic polymers that are liquid at room temperature, hydrophilic group-containing monomers that are liquid at room temperature, silane coupling agents that are liquid at room temperature, surfactants that are liquid at room temperature, and high boiling point compounds that are liquid at room temperature.

[0112] Examples of polyethylene glycol that is liquid at room temperature include polyethylene glycol having an average molecular weight of 600 or less. For example, polyethylene glycol having an average molecular weight of 600 (PEG600) has a melting point between 17° C. and 22° C., so PEG600 is liquid at room temperature (25° C.). It should be noted that polyethylene glycol having an average molecular weight of 600 or less is water-soluble.

[0113] The acrylic copolymer that is liquid at room temperature, for example, has at least a carboxyl group as a hydrophilic group, and has at least a structural unit of a (meth)acrylic acid alkyl ester monomer and a structural unit of a (meth)acrylic acid monomer containing a carboxyl group in the molecule. The mass average molecular weight of the acrylic copolymer is, for example, less than 10,000 (for example, about 2,000), and the acid value is about 70 [mgKOH / g]. As a product containing the acrylic copolymer, for example, the product name "ARUFON 3510" (manufactured by Toagosei Co., Ltd.) can be cited. It should be noted that the acrylic copolymer is water-soluble.

[0114] In addition, the acrylic copolymer that is liquid at room temperature is, for example, an acrylic acid-based water-soluble graft polymer having a hydrophilic group (polyoxyethylene chain) in the side chain. The mass average molecular weight of the acrylic copolymer is, for example, about 70,000, and the glass transition temperature Tg is about -40°C. As products containing the acrylic copolymer, for example, the product name "MARPROOF HP series" (manufactured by NOF Corporation) can be cited.

[0115] The ether-containing compound which is liquid at room temperature has a polar part and a non-polar part in its molecule. Examples of products containing the ether-containing compound include the product name "SOFBAR P series" (manufactured by NOF Corporation).

[0116] Polyoxyethylene polyoxypropylene glycol which is liquid at room temperature is a block copolymer having a polyoxyethylene structure and a polyoxypropylene structure in the molecule. Examples of products containing polyoxyethylene polyoxypropylene glycol which is liquid at room temperature include the product name "EPAN series" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0117] At room temperature, the polycationic polymer that is liquid is obtained by, for example, polymerizing at least allyl amine (diallylamine), so that the side chain part has a cyclic structure containing amine. The amine of the side chain part can be, for example, a secondary amine, a tertiary amine or a quaternary ammonium salt. The main chain of the polycationic polymer can also have a sulfonic acid group. As the product comprising the above-mentioned polycationic polymer, for example, product name "PAS series" (NITTOBO MEDICAL company system) etc. can be listed.

[0118] A polycationic polymer that is liquid at room temperature is represented by the following general formula (1), for example. In the general formula (1), x is a secondary amine, a tertiary amine, or a quaternary ammonium salt. m may be 0. n is an integer greater than 1, for example, less than 1000.

[0119]

[0120] Examples of monomers containing a hydrophilic group that are liquid at room temperature include (meth)acrylic acid type monomers having a (meth)acrylic acid structure or a (meth)acrylic ester structure in the molecule. The (meth)acrylic acid type monomers contain a carboxyl group or an ester bond (ester group) as a hydrophilic group in the molecule. Such (meth)acrylic acid type monomers are commercially available (for example, the "Light Ester" series and the "Light Acrylate" series manufactured by Kyoeisha Chemical Co., Ltd.).

[0121] The silane coupling agent, which is liquid at room temperature, has an alkoxysilane structure as a hydrophilic group in its molecule.

[0122] Examples of the silane coupling agent include silane coupling agents containing a vinyl group, an epoxy group, a styryl group, a (meth)acryloyl group, an amino group, an isocyanate group, or an acid anhydride in the molecule.

[0123] Moreover, when the silane coupling agent is classified by the functional group bonded to silicon (Si), there are trialkoxysilane type, methyldialkoxysilane type, etc. The alkoxy group may be a methoxy group or an ethoxy group.

[0124] As these silane coupling agents, products such as "KBM series" (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used.

[0125] The surfactant that is liquid at room temperature contains an anionic hydrophilic group, a cationic hydrophilic group, or a nonionic hydrophilic group (polyoxyethylene chain, etc.) as a hydrophilic group in the molecule. When the surfactant that is liquid at room temperature is a polymer compound, the hydrophilic group may also be an acrylonitrile group or an ester bond, etc. The chemical name of the surfactant that is liquid at room temperature and the product containing the surfactant are described below.

[0126] The liquid surfactant is, for example, a quaternary ammonium salt type cationic active agent of alkyl trimethyl type or alkyl dimethyl benzyl type. The alkyl portion is, for example, lauryl, palmityl, stearyl, or behenyl. The liquid surfactant is, for example, included in the product name "NISSAN CATION" series (manufactured by NOF Corporation).

[0127] The liquid surfactant is, for example, an acetate of an aliphatic amine (laurylamine or stearylamine). The surfactant is included in, for example, the product name "NISSAN CATION" series (manufactured by NOF Corporation).

[0128] The liquid surfactant is, for example, polyoxyethylene lauryl ether sulfate sodium salt. The surfactant is included in, for example, the product name "TRAX" series (manufactured by NOF Corporation).

[0129] The liquid surfactant is, for example, sodium salt of fatty acid amide ether sulfate. The surfactant is included in, for example, the product name "SUNAMIDE" series (manufactured by NOF Corporation).

[0130] The liquid surfactant is, for example, sodium methyl taurate, a fatty acid. The surfactant is included in, for example, the product name "DIAPON" series (manufactured by NOF Corporation).

[0131] The liquid surfactant is, for example, polyoxyalkylene alkyl ether such as polyoxyethylene branched alkyl ether. The surfactant is included in, for example, the product name "DISPANOL" series (manufactured by NOF Corporation).

[0132] The liquid surfactant is, for example, an aminoacetic acid betaine-type amphoteric surfactant such as aliphatic alkyl dimethyl aminoacetic acid betaine or fatty acid amidopropyl dimethyl aminoacetic acid betaine.

[0133] The above-mentioned surfactant is included in, for example, the product name "NISSAN ANON" series (manufactured by NOF Corporation).

[0134] The liquid surfactant is, for example, polyoxyethylene alkylamine. The surfactant is included in, for example, the product name "NYMEEN" series (manufactured by NOF Corporation).

[0135] The high boiling point compound that is liquid at room temperature is, for example, an organic compound having a boiling point of 100° C. or higher. The boiling point of the compound may be lower than 250° C.

[0136] The molecular weight of the high boiling point compound which is liquid at room temperature is, for example, 200 or less, or preferably 150 or less.

[0137] Examples of high-boiling-point compounds that are liquid at room temperature include monohydric alcohols such as butanol and isobutanol; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, or glycerol; esters such as propyl acetate, isobutyl acetate, butyl acetate, or ethyl lactate; ketones such as methyl isobutyl ketone (MIBK) or cyclohexanone; glycol monoethers such as ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, or 1-methoxy-2-propanol; glycol diethers such as ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; and nitrogen-containing organic substances such as N,N-dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP).

[0138] As the high boiling point compound which is liquid at room temperature, diethylene glycol, glycerin, or N-methyl-2-pyrrolidone is preferred.

[0139] The liquid component is preferably water-soluble. A compound having a solubility of 1 g or more in 100 g of water at 25° C. is considered to be water-soluble. When the liquid component is water-soluble, the protective layer 11 can be removed more easily with a liquid containing water.

[0140] The liquid component is preferably a low-volatility compound regardless of the molecular structure. A compound having a vapor pressure of 2.5 hPa or less at 20° C. is considered to be low-volatility.

[0141] When the protective layer 11 is removed by a liquid containing water, the protective layer 11 only needs to have a predetermined hydrophilicity or higher. When the protective layer 11 has a predetermined hydrophilicity or higher, at least a portion of the protective layer 11 is usually dissolved in the liquid containing water.

[0142] When the protective layer 11 is removed by a liquid containing water, the water absorption rate of the protective layer 11 is preferably 2.0% by mass or more. Thus, the protective layer 11 is more easily dissolved in the liquid containing water. The water absorption rate can be increased, for example, by increasing the content ratio of the hydrophilic group in the hydrophilic polymer or by increasing the content of the liquid component in the protective layer 11. The water absorption rate of the protective layer 11 can be, for example, 10.0% by mass or less.

[0143] The water absorption rate of the protective layer 11 is obtained based on the measured value using the Karl Fischer coulometric method. Specifically, a test sample that has reached a steady state under an environment of a temperature of 23°C and a humidity of 50 RH% is heated at 150°C for 3 minutes using a water vaporization device, and the vaporized water is measured. The water absorption rate is obtained based on the ratio of the measured water content to the mass of the heated test sample.

[0144] In the protective layer 11, the amount of the liquid component is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, relative to 100 parts by mass of the hydrophilic polymer. Thus, the protective layer 11 is more easily processed in that microcracks are less likely to occur when subjected to shear force during cutting, and can be more fully adhered to the protected object.

[0145] The amount of the liquid component may be 60 parts by mass or less, or 40 parts by mass or less, relative to 100 parts by mass of the hydrophilic polymer. When the protective layer 11 does not contain an excessive amount of liquid component, the moldability of the protective layer 11 is improved.

[0146] In this embodiment, the adhesion of the protective layer 11 to the protected object is represented by, for example, a peeling force when peeling the protective layer 11 from a silicon bare wafer as a substrate. The peeling force of the protective layer 11 may be 100 [N / 100mm] or less, or 80 [N / 100mm] or less. It should be noted that the peeling force may be 0.2 [N / 100mm] or more.

[0147] The above-mentioned peeling force is measured under the following measurement conditions.

[0148] In order to measure the peeling force of one surface of the above-mentioned protective layer 11 (the surface attached to the side of the silicon bare wafer), a sample for measurement is prepared as follows. First, a substrate tape is attached to the surface of the protective layer 11 opposite to the above-mentioned one surface using a hand roller at 25°C. Next, the sample for measurement is processed so as to be 100 mm wide, and a bare wafer is attached to the above-mentioned one surface of the protective layer 11. The attachment is carried out under the conditions of 90°C and 10 mm / sec. Then, in an atmosphere of 23°C, the substrate tape and the protective layer 11 are peeled off from the bare wafer at a peeling angle of 180° and a peeling speed of 300 mm / min, and the peeling force is measured. It should be noted that as a measuring device, for example, "AUTOGRAPH (manufactured by SHIMADZU)" can be used.

[0149] When the dynamic viscoelasticity of the protective layer 11 is measured, the storage modulus E' of the protective layer at 70°C can be less than 0.1 GPa (less than 100 MPa). Since the storage modulus E' is moderately small, the protective layer 11 can have better tracking properties when subjected to deformation force. In addition, the wettability of the interface with the protected object becomes better, so the adhesion to the protected object can be better. It should be noted that the storage modulus E' of the protective layer 11 at 70°C can be greater than 0.01 GPa (greater than 10 MPa).

[0150] When the dynamic viscoelasticity of the protective layer 11 is measured, the temperature at which the loss modulus E" is the maximum value can be below 35°C. As a result, the protective layer 11 can be bonded to the protected object at a lower temperature to ensure sufficient adhesion. It should be noted that the temperature at which the loss modulus E" is the maximum value can be above 5°C.

[0151] When the dynamic viscoelasticity of the protective layer 11 is measured, the peak temperature of Tanδ(E” / E'), which is the ratio of the loss modulus E” to the storage modulus E', is preferably lower than 70°C. As a result, the protective layer 11 can have better followability when subjected to a deformation force. In addition, the wettability of the interface with the protected object becomes better, and thus the adhesion to the protected object can become better. In addition, the protective layer 11 can be made to adhere to the protected object at a lower temperature, so that the protection process described later can be carried out at a lower temperature, thereby further suppressing the thermal energy cost used for the heating required in the protection process.

[0152] It should be noted that the peak temperature of Tan δ (E″ / E′) may be 25° C. or higher, or 30° C. or higher. When the peak temperature is higher, the handling of the protective layer 11 can be made easier.

[0153] The dynamic viscoelasticity measurement of the protective layer 11 was performed using a solid viscoelasticity measuring device in a tensile mode under the following test conditions.

[0154] Thickness of the test sample: 50 μm.

[0155] Width of test sample: 10 mm.

[0156] Distance between chucks: 20mm.

[0157] Heating rate: 10°C / min.

[0158] Test temperature: 0℃~120℃.

[0159] Frequency: 1Hz.

[0160] The storage modulus E' and loss modulus E", are measured over time, and Tanδ is calculated over time according to the calculation formula Tanδ = E", / E'. The higher the Tanδ, the higher the viscosity. The peak shape of Tanδ is depicted, and the temperature when the peak is reached is read. It should be noted that the average value of three measurements is used as the peak value of the storage modulus E' and Tanδ at 70°C.

[0161] The above-mentioned protection sheet 1 can be produced by a common method.

[0162] For example, the protective layer 11 can be produced by mixing the above-mentioned hydrophilic polymer, liquid component, solvent, etc. by a common method, applying the mixture to the release liner 15, and then volatilizing the solvent from the mixture.

[0163] The protective sheet 1 is used by, for example, peeling the release liner 15 from the protective layer 11 and attaching the protective layer 11 to a protected surface of an object to be protected. Thereafter, the protective layer 11 protecting the protected surface is removed from the protected surface by a liquid containing water.

[0164] Next, a method of using the protective sheet 1 of the present embodiment will be described. Specifically, a method of manufacturing an electronic device using the protective sheet 1 will be described as an example. In the above example, the object to be protected is a substrate as a member constituting the electronic device.

[0165] The electronic device manufactured using the protective sheet 1 may be, for example, a semiconductor device such as a semiconductor integrated circuit having a semiconductor chip, or a system LSI device having a complementary metal oxide semiconductor (CMOS), or a device having a mechanical component, sensor, actuator, or electronic circuit integrated on a silicon substrate, a glass substrate, or an organic material substrate (MEMS, Micro Electro Mechanical Systems) by micromachining technology. The manufactured electronic device may be a device having a wiring substrate.

[0166] In the method for manufacturing an electronic device using the protective sheet 1, as Figure 2B As shown, the protected surface Sa as one surface of the substrate S is protected by a protective layer 11. It should be noted that the protected surface Sa may or may not be provided with circuit components (described in detail later). In other words, the protected surface Sa of the substrate S may be, for example, a circuit surface with a circuit formed thereon, or a non-circuit surface without a circuit formed thereon.

[0167] The protective layer 11 can be formed on the protected surface Sa of the substrate S. For example, the protective layer 11 can be formed by applying a mixture of the above-mentioned hydrophilic polymer, liquid component, and solvent to the protected surface Sa of the substrate S, and then volatilizing the solvent. The formed protective layer 11 contains the above-mentioned hydrophilic polymer and liquid component, and thus has good adhesion to the protected surface Sa of the substrate S.

[0168] The material of the substrate S is not particularly limited as long as it is plate-shaped. Examples of the substrate include a semiconductor wafer, a substrate constituting a sensor wafer such as CMOS or MEMS, a dummy wafer, or a wiring substrate.

[0169] The manufacturing method of an electronic device using the above-mentioned protective sheet 1 includes: a process of protecting a protected surface by overlapping the protective layer 11 of the above-mentioned protective sheet 1 on a protected surface of a substrate (protection process); and a process of removing the protective layer 11 by bringing the protective layer 11 overlapping the protected surface into contact with a liquid containing water (removal process).

[0170] The details of the protective layer 11 are as described above.

[0171] In the above-mentioned method for manufacturing an electronic device, a step (wetting step) of increasing the humidity of the gas in contact with the protected surface Sa of the substrate S may be performed before the protection step as needed (see Figure 2A ) By performing the wetting step, the adhesion of the protective layer 11 to the protected surface Sa can be improved.

[0172] The wetting step can be performed, for example, by bringing a gas containing water vapor into contact with the surface to be protected, spraying water in a mist form onto the surface to be protected, or applying water to the surface to be protected.

[0173] In the above-mentioned protection step, the protection layer 11 of the protection sheet 1 is overlapped on the protected surface Sa of the substrate S. In the protection step, for example, the protection layer 11 is overlapped on the surface of the substrate S on the side where at least one of the circuit wiring, the sensor part, and the electrode part is configured as a circuit component. In the above-mentioned protection step, it is preferable to overlap the protection layer 11 on at least one surface of the substrate S in such a manner that the circuit wiring, the sensor part, or the electrode part is covered by the protection layer 11. As the circuit component, for example, circuit wiring, electrode part, or transistor, diode, or sensor part (light sensor or vibration sensor, etc.) and other elements can be listed.

[0174] In the above-mentioned method for manufacturing an electronic device, the following steps may be performed as required, for example: Figure 2C As shown, the stack of the stacked substrate S and the protective layer 11 is divided and fragmented at intervals in the plane direction to produce a plurality of stacked chips S' of the fragmented substrate and the protective layer fragments 11' (eg, a dicing step).

[0175] In the removal process, Figure 2DAs shown, the protective layer 11 overlapping the protected surface of the substrate S is removed by the liquid containing water. In the removal step, when removing the protective layer 11, the protective layer 11 may be completely dissolved in the liquid containing water, or only a part of the protective layer 11 may be dissolved in the liquid containing water.

[0176] Hereinafter, a method for manufacturing a semiconductor device for manufacturing a semiconductor integrated circuit will be given as a specific example, and the above-mentioned manufacturing method will be described in detail with reference to the drawings.

[0177] In a method for manufacturing a semiconductor device (electronic device), for example, a semiconductor chip X is cut out from a semiconductor wafer W having a circuit surface formed thereon, and a semiconductor device having the cut semiconductor chip X is assembled. In the method for manufacturing a semiconductor device described below, at least the protective layer 11 of the protective sheet 1 and the dicing tape 20 (see Figure 3A ) to manufacture semiconductor devices. The dicing tape 20 has a base material layer 21 and an adhesive layer 22. These sheets and tapes are used as auxiliary tools for manufacturing semiconductor devices. It should be noted that a dicing die bonding film 50 (see Figure 3B ) As the dicing tape 20 and the dicing die-bonding film 50 , commercially available products can be used respectively.

[0178] Generally, a method for manufacturing a semiconductor device includes a front process of forming a circuit surface on one side of a bare wafer using a highly integrated electronic circuit, and a back process of cutting out semiconductor chips X from the semiconductor wafer W having the circuit surface formed thereon for assembly.

[0179] In the post-process, for example, a wafer (semiconductor wafer W) as a substrate having a circuit surface formed thereon is diced into small semiconductor chips X. Then, the diced semiconductor chips X are bonded to an adherend to assemble a semiconductor integrated circuit (semiconductor device).

[0180] Hereinafter, regarding specific examples of the method for manufacturing a semiconductor device, first to third examples will be described in detail.

[0181] It should be noted that the first example is described as “I” in the drawings showing the manufacturing method. Similarly, the second example and the third example are described as “II” and “III” in the drawings, respectively.

[0182] "First Example of Method for Manufacturing a Semiconductor Device"

[0183] The method for manufacturing a semiconductor device according to the first example includes an assembling step of cutting out a semiconductor chip X from a semiconductor wafer W (substrate) having a circuit surface formed thereon, and assembling a semiconductor device having the semiconductor chip X.

[0184] The above-mentioned assembly process at least includes: a protection process, on the circuit surface of at least one surface of the semiconductor wafer W, a protective layer 11 for protecting the circuit component is superimposed to protect the circuit surface (protected surface); a fixing process, affixing the semiconductor wafer W with the circuit component formed on one side to the dicing die bonding film 50 (overlapping the die bonding sheet 30 of the dicing tape 20), and fixing the semiconductor wafer W to the dicing die bonding film 50; a peeling process implemented as needed, by peeling between the protective layer 11 and the peeling liner 15 to remove the peeling liner 15; by separating the semiconductor wafer W, the protective layer 11, and the peeling liner 15 in a manner of being spaced apart in the surface direction. The present invention relates to a process of manufacturing a semiconductor chip X obtained by cutting a semiconductor wafer W into small pieces, a small piece 11' of a protective layer, and a plurality of small pieces of a stacked product obtained by stacking small pieces 30' of a chip bonding sheet 30; a removal process of removing small pieces 11' of the protective layer overlapping the circuit surface of the semiconductor chip X by bringing them into contact with a liquid containing water; a picking process of peeling off the dicing tape 20 and the small piece 30' of the chip bonding sheet to take out the semiconductor chip X with the small piece 30' of the chip bonding sheet attached thereto; and a bonding process of bonding the taken out semiconductor chip X to an adherend via the small piece 30' of the chip bonding sheet.

[0185] When these steps are performed, the protective layer 11 and the dicing die-bonding film 50 having the dicing tape 20 described above are used as manufacturing auxiliary tools.

[0186] In the manufacturing method of the first example, a blade dicing process is implemented as a process for producing a plurality of small pieces of the above-mentioned stacked product. In the blade dicing process, the chip bonding sheet 30, the semiconductor wafer W, and the protective layer 11 are cut into small pieces by a dicing blade T or the like, and a semiconductor chip X (die) formed by cutting the semiconductor wafer W into small pieces is produced.

[0187] The semiconductor wafer W is configured to obtain a plurality of semiconductor chips X. Specifically, the semiconductor wafer W is configured to be divided and divided into small pieces with intervals along a plurality of directions along the surface (for example, directions along the surface and orthogonal to each other), thereby producing a plurality of semiconductor chips X. In addition, the semiconductor wafer W has a circuit surface on which at least one circuit component is arranged on one surface.

[0188] In the semiconductor industry in recent years, with the further progress of integration technology, thinner semiconductor chips (e.g., thickness of 20 μm or more and 50 μm or less) are desired. The shape of the semiconductor chip when viewed from one side in the thickness direction is, for example, a rectangle, and the length of one side is, for example, a predetermined length of 5 mm or more and 20 mm or less.

[0189] In the protection process, Figure 4AAs shown, a protective layer 11 is stacked on the circuit surface of the semiconductor wafer W. By stacking the protective layer 11 on the circuit surface of the semiconductor wafer W, the circuit surface can be protected by the protective layer 11 before the protective layer 11 is removed. Therefore, it is possible to prevent dirt and the like from being attached to the circuit surface of the semiconductor wafer W covered by the protective layer 11.

[0190] For example, as described below, the protecting step and the fixing step may be performed simultaneously.

[0191] In the fixing process, first, after the dicing ring R is mounted on the adhesive layer 22 of the dicing tape 20, the dicing ring R may be fixed to the retainer H of the expansion device. Figure 4A As shown, the semiconductor wafer W, the protective layer 11, and the release liner 15 are simultaneously attached to the die bonding sheet 30 overlapped with the dicing tape 20. For example, in this way, the semiconductor wafer W is fixed to the die bonding sheet 30. Then, the protective layer 11 is pressed against the semiconductor wafer W via the release liner 15, thereby attaching the protective layer 11 to the above-mentioned circuit surface.

[0192] When the release liner 15 is used as described above, a peeling step may be performed to remove the release liner 15 by peeling the release liner 15 from the protective layer 11 .

[0193] In the blade cutting process, for example Figure 4B and Figure 4C As shown, the semiconductor wafer W is cut. In detail, the protective layer 11 and the semiconductor wafer W are cut into a specified size together with the chip bonding sheet 30 to form a semiconductor chip X with a small piece 30' of the chip bonding sheet. At this time, a small piece 11' of the protective layer is also formed. The blade cutting process step is carried out according to a conventional method, for example, using a cutting blade T. In the blade cutting process step, for example, a cutting method called full cutting can be adopted in which the cutting is carried out to reach the chip bonding sheet 30. There is no particular limitation on the cutting device used in the blade cutting process step, and a conventionally known device can be used.

[0194] In the blade dicing process, foreign matter such as chips may be generated as the semiconductor wafer W is cut. At this time, since the protected surface of the semiconductor wafer W is protected by the protective layer 11, it is possible to suppress the foreign matter from being attached to the protected surface.

[0195] In the removal process, for example Figure 4D As shown, a liquid containing water is brought into contact with the plurality of small pieces 11' of the protective layer, and at least a portion of each small piece 11' is dissolved in the liquid, thereby removing each small piece 11' of the protective layer from the surface (protected surface) of the semiconductor chip X.

[0196] By removing the small pieces 11' of the protective layer in this way, all of the plurality of small pieces 11' of the protective layer can be removed more easily, and the amount of foreign matter attached to the surface of the semiconductor chip can be reduced more easily by the above-mentioned liquid. In addition, the surface (protected surface) of each semiconductor chip X overlapped by the small pieces 11' of the protective layer can also be cleaned by the liquid.

[0197] In the removal step, the small pieces 11' of the protective layer can be removed by dissolving all of the small pieces of the protective layer (the plurality of small pieces 11' of the protective layer) in the liquid. Alternatively, a portion of the constituent components of the small pieces 11' of the protective layer can be dissolved in the liquid to peel off the small pieces 11' whose adhesion to the semiconductor chip X is weakened from the semiconductor chip X, thereby removing the plurality of small pieces 11' of the protective layer.

[0198] The liquid containing water is not particularly limited as long as it is a liquid substance containing water. The above-mentioned liquid can contain more than 30% by mass of water, can contain more than 50% by mass of water, can contain more than 70% by mass of water, can contain more than 80% by mass of water, and can contain more than 90% by mass of water.

[0199] The liquid may contain a component that dissolves in water in addition to water. As the component, for example, a water-soluble organic solvent may be cited. As the water-soluble organic solvent, for example, a monohydric alcohol having a carbon number of 4 or less such as propanol such as methanol, ethanol, or isopropanol, or butanol such as tert-butyl alcohol may be cited.

[0200] In the removal process of the first example, the small piece 11' of the protective layer may be immersed in the stirred liquid to make the liquid contact the small piece 11' of the protective layer. Alternatively, the liquid ejected from a nozzle or the like may be made contact with the small piece 11' of the protective layer. 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.

[0201] For example, in the removal process, a disk-shaped table supporting the dicing tape 20 from below is rotated circumferentially, and the liquid is sprayed onto the semiconductor chips X of the small pieces 30' attached to the die bonding sheet. Thus, a plurality of small pieces 11' overlapping the protective layers of the semiconductor chips X can be removed.

[0202] According to the method for manufacturing a semiconductor device of the first example, the protective layer 11 is stacked 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 before the protective layer 11 is removed.

[0203] In the picking process, Figure 4EAs shown, the small piece 30' of the die bonding sheet with the semiconductor chip X is peeled off from the adhesive layer 22 of the dicing tape 20. Specifically, the pin member P is raised to push up the semiconductor chip X to be picked up through the dicing tape 20. The pushed-up semiconductor chip X and the small piece 30' of the die bonding sheet are held by the suction jig J.

[0204] When the pickup process is performed in this way, the small piece 30' of the die bonding sheet attached to the semiconductor chip X needs to be easily peeled off from the adhesive layer 22 of the dicing tape 20. The dicing tape 20 described above is designed to exhibit such performance well.

[0205] For example, the dicing tape 20 is configured such that, by irradiating active energy rays (e.g., ultraviolet rays), the adhesive layer 22 is cured and the adhesive force of the adhesive layer 22 is reduced. Since the adhesive layer 22 is cured after irradiation, the adhesive force of the adhesive layer 22 can be reduced, so that after irradiation, the semiconductor chip X and the small piece 30' of the chip bonding sheet can be easily peeled off from the adhesive layer 22. Dicing tapes 20 having such a configuration are already commercially available.

[0206] In the bonding process, the semiconductor chip X with the die bonding sheet 30' attached thereto is bonded to the adherend Z. In other words, the semiconductor chip X is bonded to the adherend such as the substrate or the semiconductor chip X through the die bonding sheet 30'. Figure 4F As shown, a plurality of semiconductor chips X in a state where a small sheet 30 ′ of a die bonding sheet is attached thereto may be stacked.

[0207] In addition, as an adherend Z, for example, an interposer, a wiring circuit board, or a small piece of a substrate (a case where small pieces of a substrate are stacked and laminated) etc. can be cited.

[0208] In the first example, in order to protect the semiconductor chip X after the bonding step, a resin sealing step of sealing (covering) the semiconductor chip X with a thermosetting resin or the like may be performed.

[0209] Next, the second example is described in detail. It should be noted that, regarding the second example, the same description as the first example is not repeated. In the second example, unless otherwise specified, the same operation as the first example can be performed.

[0210] “Method for manufacturing a semiconductor device according to the second example”

[0211] The semiconductor device manufacturing method of the second example is different from the first example mainly in that the semiconductor wafer W is cut into small pieces by a so-called DBG process in which the semiconductor wafer W is half-cut to reduce the thickness of the semiconductor wafer W. In the second example, in order to process the semiconductor wafer W into a chip (die) by cutting, a groove is formed in the semiconductor wafer W, and then the semiconductor wafer W is ground to reduce the thickness.

[0212] The manufacturing method of the semiconductor device of the second example includes, for example, a half-cutting process step of forming grooves on the circuit surface of the semiconductor wafer W for cutting the semiconductor wafer W into small pieces to produce a plurality of semiconductor chips X; a back grinding process of grinding the surface of the semiconductor wafer W opposite to the circuit surface to reduce the thickness of the semiconductor wafer W; a fixing process of affixing the semiconductor wafer W with the reduced thickness to the die bonding sheet 30 on the dicing tape 20 to fix the semiconductor wafer W to the die bonding sheet 30; an expansion process of cutting the semiconductor wafer W, the die bonding sheet 30, and the protective layer 11 into small pieces together by stretching the dicing tape 20; a removal process of removing the plurality of small pieces 11' affixed to the protective layer of the semiconductor chip X; a picking process of peeling the semiconductor chip X from the small piece 30' of the die bonding sheet to take out the semiconductor chip X; and a bonding process of bonding the taken out semiconductor chip X to an adherend via the small piece 30' of the die bonding sheet.

[0213] In the second example, a wafer processing tape is attached to the surface of the semiconductor wafer W opposite to the protected surface, and a dividing groove for dividing the semiconductor wafer W into small pieces is formed. The groove is formed in the semiconductor wafer W so as not to penetrate in the thickness direction.

[0214] Then, for example Figure 5A As shown in FIG. 1 , a back grinding tape B is stacked on the circuit surface of the semiconductor wafer W having grooves formed thereon, and the back grinding tape B protects the protected surface (circuit surface). Figure 5B As shown in the figure, the surface of the semiconductor wafer W where no circuit components are arranged is ground with the back grinding tape B attached. For example, the grinding process (back grinding process) using a grinding pad is performed 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.

[0215] Then, the surface of the semiconductor wafer W subjected to the grinding process (the surface on which the circuit components are not arranged) is attached to the die bonding sheet 30 on the dicing tape 20, and a fixing step is performed (see Figure 5C ).

[0216] Next, an expansion process is performed to divide the semiconductor wafer W and the protective layer 11 into small pieces. In the expansion process, Figure 5DAs shown, in a state where the semiconductor wafer W is attached to the chip bonding sheet 30 on the dicing tape 20, the dicing tape 20 is stretched in the surface direction in a manner that expands the surface area of ​​the dicing tape 20. As a result, the stack of the protective layer 11, the semiconductor wafer W, and the chip bonding sheet 30 is divided into small pieces, and the interval between the adjacent semiconductor chips X formed by the small pieces is expanded in the surface direction. In detail, the dicing tape 20 is stretched in a manner that expands in the surface direction by pushing up the push-up member U possessed by the expansion device from the lower side of the dicing tape 20. As a result, under specific temperature conditions, the semiconductor wafer W, the chip bonding sheet 30, and the protective layer 11 are broken into small pieces. The above-mentioned temperature conditions are, for example, above -20°C and below 0°C. By lowering the push-up member U, the expanded state (up to this point is a low-temperature expansion process) is released.

[0217] When the expansion process is performed at a low temperature, the protective layer 11 and the die bonding sheet 30 need to be cut and divided into small pieces. The protective layer 11 and the die bonding sheet 30 are designed to be cut well at this time.

[0218] Furthermore, in the expansion process, the dicing tape 20 may be stretched again under a higher temperature condition (e.g., 10° C. or higher and 25° C. or lower) to expand the surface area of ​​the dicing tape 20. Thus, the semiconductor chips X adjacent to each other are pulled apart along the surface direction of the dicing tape 20, and the cut (interval) may be further expanded (normal temperature expansion process).

[0219] Then, in the removal step, the small piece 11' of the protective layer attached to the semiconductor chip X can be removed by the same method as described above. In addition, in the same method as described above, a pickup step of taking out the semiconductor chip X and a bonding step of bonding the semiconductor chip X to an adherend can be performed.

[0220] In the second example, steps not particularly mentioned can be performed in the same manner as the steps in the first example.

[0221] It should be noted that in the second example, Figure 5E As shown in FIG. 1 , when the semiconductor wafer W is ground using the back grinding tape B, a protective layer 11 can be arranged between the back grinding tape B and the semiconductor wafer W. In this state, the grinding process (back grinding process) can be performed, so as Fig. 5F As shown in FIG. 1 , the semiconductor wafer W can be thinned to a desired thickness. Figure 5G As shown, the fixing step can be performed in a state where the back grinding tape B, the protective layer 11, and the semiconductor wafer W are stacked.

[0222] Next, the third example will be described in detail. It should be noted that, regarding the third example, the same description as the first example or the second example will not be repeated. In the third example, unless otherwise specified, the same operation as the first example or the second example can be performed.

[0223] “Third Example Method for Manufacturing a Semiconductor Device”

[0224] The semiconductor device manufacturing method of the third example is different from the first or second example mainly in that a fragile portion is formed inside the semiconductor wafer W and the semiconductor wafer W is divided into small semiconductor chips X with the fragile portion as a boundary.

[0225] The manufacturing method of the semiconductor device of the third example includes, for example, a fixing step of attaching a semiconductor wafer W having circuit components formed on both sides to a dicing tape 20 to fix the semiconductor wafer W to the dicing tape 20; a protecting step of attaching a protective layer 11 to the circuit surface of the semiconductor wafer W that is exposed to protect the circuit surface; a stealth processing step of forming a fragile portion inside the semiconductor wafer W to which the protective layer 11 is attached by using a laser to prepare for cutting the semiconductor wafer W into small pieces into semiconductor chips X (die); an expanding step of stretching the dicing tape 20 to cut the semiconductor wafer W and the protective layer 11 into small pieces; a removing step of removing a plurality of small pieces 11' of the protective layer attached to the semiconductor chip X; a picking step of peeling the semiconductor chip X and the adhesive layer 22 to take out the semiconductor chip X; and a bonding step of bonding the taken-out semiconductor chip X to an adherend.

[0226] When these steps are performed, the protective layer 11 and the dicing tape 20 described above are used as manufacturing auxiliary tools.

[0227] In the third example, Figure 5A As shown, the chip bonding sheet 30 is not arranged on the dicing tape 20, and the semiconductor wafer W is stacked on the adhesive layer 22 of the dicing tape 20 (refer to Fig. 6A ).

[0228] In the stealth process, a weak portion for cutting the semiconductor wafer W into semiconductor chips X is formed inside the semiconductor wafer W. By irradiating the semiconductor wafer W with laser light L, a weak portion is formed inside the semiconductor wafer W (see Fig. 6A and Figure 6B ). The laser L is irradiated, for example, from the dicing tape side toward the semiconductor wafer W. The stealth processing step can be performed, for example, using a commercially available stealth dicing device.

[0229] It should be noted that, before the fixing step, the semiconductor wafer W may be irradiated with laser light to form a weak portion inside the wafer in advance.

[0230] In the expansion process, Figure 6C As shown in FIG. 1 , the dicing tape 20 is stretched in the surface direction in such a manner as to expand the area of ​​the dicing tape 20, thereby dividing the semiconductor wafer W and the protective layer 11 into small pieces. Specifically, by stretching the dicing tape 20, the semiconductor wafer W can be divided into small pieces of semiconductor chips X with the above-mentioned fragile portion inside the semiconductor wafer as a boundary. At this time, the semiconductor wafer W is divided into small pieces into semiconductor chips X, and the protective layer 11 is also divided into small pieces.

[0231] The removal process of the third example is as follows Fig.6D As shown, the removal process can be carried out in the same manner as in the first example.

[0232] In the pickup step of the third example, the semiconductor chip X is peeled off from the adhesive layer 22 of the dicing tape 20 . When the pickup step is performed in this manner, the semiconductor chip X is peeled off from the adhesive layer 22 of the dicing tape 20 .

[0233] In the third example, the bonding step can be performed in the same manner as in the first example or the second example.

[0234] In the third example, steps not particularly mentioned can be performed in the same manner as the steps in the first example or the second example.

[0235] It should be noted that, in the third example, the back grinding tape B can be used to grind the semiconductor wafer W. When performing the above grinding process, Fig. 6E As shown in FIG. 1 , a protective layer 11 can be arranged between the back grinding tape B and the semiconductor wafer W. In this state, grinding (back grinding) can be performed, so as Fig. 6F As shown in FIG. 1 , the semiconductor wafer W can be thinned to a desired thickness. Figure 6G As shown, the fixing step can be performed in a state where the back grinding tape B, the protective layer 11, and the semiconductor wafer W are stacked.

[0236] The protective sheet of the present invention and the method for producing an electronic device using the protective sheet are as described above, but the present invention is not limited to the protective sheet or the method for producing the electronic device using the protective sheet.

[0237] That is, various modes used in a general method for manufacturing an electronic device or the like can be adopted within a range not impairing the effects of the present invention.

[0238] Matters disclosed by this specification include the following. (1)

[0240] A protective sheet comprises: a protective layer which is removed by a liquid containing water after protecting at least a part of the surface of a protection object, the protective layer comprising a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in the molecule. (2)

[0242] The protective sheet according to the above (1), wherein the liquid compound is water-soluble. (3)

[0244] The protective sheet according to (1) or (2) above, wherein the protective layer contains 1 part by mass or more and 60 parts by mass or less of the liquid compound relative to 100 parts by mass of the hydrophilic polymer. (4)

[0246] The protective sheet according to any one of (1) to (3) above, wherein the storage modulus E' of the protective layer at 70° C. is 0.1 GPa or less. (5)

[0248] The protective sheet according to any one of (1) to (4) above, wherein when the protective layer is subjected to dynamic viscoelasticity measurement, a peak temperature of Tan δ (E" / E') which is a ratio of loss modulus E" to storage modulus E' is lower than 70°C. (6)

[0250] A protective sheet according to any one of (1) to (5) above, wherein the hydrophilic polymer has a plurality of hydrophilic groups in its molecule, and the hydrophilic groups are at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, and a polyoxyethylene group. (7)

[0252] The protective sheet according to any one of (1) to (5) above, wherein the hydrophilic polymer is at least one selected from the group consisting of polyvinyl alcohol, polyvinyl pyrrolidone, a water-soluble polyester polymer, polyethylene oxide, polyacrylic acid, and polyvinyl acetamide. (8)

[0254] A protective sheet according to any one of (1) to (7) above, wherein the liquid compound has a hydrophilic group in its molecule, and the hydrophilic group is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, and a polyoxyethylene group.

[0255] Example

[0256] Next, the present invention will be described in further detail by means of experimental examples, but the present invention is not limited thereto.

[0257] (Examples 1 to 4, Comparative Examples 1 and 2, Reference Example 1)

[0258] The protective sheets of each of the Examples, Comparative Examples, and Reference Example 1 were prepared as follows. Specifically, the following raw materials were prepared as a hydrophilic polymer and a liquid component.

[0259] After the hydrophilic polymer and the liquid component were dispersed in water, the solution was heated to 90° C. to dissolve the hydrophilic polymer and the liquid component, thereby preparing a PVA aqueous solution.

[0260] The PVA aqueous solution was applied to a release liner (PET film, 50 μm thick). The release liner had a silicone release-treated surface, and the PVA aqueous solution was applied to the surface using an applicator. Furthermore, a drying treatment was performed at 110° C. for 2 minutes to form a protective layer (film formation) with a thickness of 10 μm that overlapped one surface of the release liner.

[0261] Details of the raw materials of the protective layers used in the examples and comparative examples are shown in Table 1 and below.

[0262] [Material for protective layer]

[0263] ·Hydrophilic polymer: polyvinyl alcohol (hereinafter, all are water-soluble).

[0264] 1) PVA-1: saponification degree: 82 (mol %), average polymerization degree: 500.

[0265] (Made by KURARAY Co., Ltd.)

[0266] 2) PVA-2: saponification degree: 65 (mol %), average degree of polymerization: 240.

[0267] (Made by JAPAN VAM&POVAL Co., Ltd.)

[0268] 3) PVA-3: saponification degree: 98 (mol%), average degree of polymerization: 1200.

[0269] (Made by Mitsubishi Chemical Corporation.)

[0270] Liquid ingredients (hereinafter, all are water-soluble).

[0271] 1) PEG300: polyethylene glycol 300 (average molecular weight 300, commercially available product).

[0272] Vapor pressure at 20°C: less than 2.0 hPa.

[0273] 2) PEG600: polyethylene glycol 600 (average molecular weight 600, commercially available product).

[0274] Vapor pressure at 20°C: less than 2.0 hPa.

[0275] 3) Acrylic acid copolymer: product name "ARUFON UC-3510" (manufactured by Toagosei Co., Ltd.).

[0276] An acrylic copolymer having at least a structural unit of an alkyl (meth)acrylate and a structural unit of a carboxyl group-containing (meth)acrylate in a molecule.

[0277] Mass average molecular weight: about 2000, acid value: about 70 [mgKOH / g].

[0278] Vapor pressure at 20°C: less than 2.0 hPa.

[0279] 4) PEG400: polyethylene glycol 400 (average molecular weight 400, commercially available product).

[0280] Vapor pressure at 20°C: less than 2.0 hPa.

[0281] [Table 1]

[0282]

[0283] The physical properties (dynamic viscoelasticity) of the produced protection sheet were measured as follows. In addition, the performance of the protection sheet was evaluated.

[0284] <Measurement of dynamic viscoelasticity of protective sheet>

[0285] The dynamic viscoelasticity measurement of the protective sheet was carried out under the above-mentioned measurement conditions using a solid viscoelasticity measuring apparatus (RSA3 manufactured by TA Instruments).

[0286] The temperature at which the storage modulus E' and the loss modulus E" at 70°C are maximized, and the temperature at which tan δ (E" / E') shows a peak value are determined.

[0287] <Ease of preparing the protective layer (film formation)>

[0288] The film formation was visually observed and evaluated using three levels: ○ (good), slightly good (△), and poor (×).

[0289] <About processability (how difficult it is to generate micro cracks when cutting the protective layer)>

[0290] When the protective layer was cut into a desired size, it was visually observed whether microcracks were generated. The case where no microcracks were generated was evaluated as ○ (good), and the case where microcracks were generated was evaluated as poor (×).

[0291] <Adhesion of protective layer to protected object>

[0292] The peel strength between the protective layer and the silicon bare wafer was measured by the above-mentioned measuring method. If the peel strength of the protective layer to the silicon bare wafer is 0.2 N / 100 mm or more, it can be said that the adhesion is good.

[0293] <Removability of protective layer by water>

[0294] In order to remove the protective layer, the stack of the silicon bare wafer and the protective layer was immersed in 25°C water for 30 seconds. After that, the water used to remove the protective layer was removed. Furthermore, the surface of the silicon bare wafer was analyzed by Fourier transform infrared spectrophotometer (FT-IR). Through the above analysis, it was confirmed whether there was any residual organic matter. It should be noted that the evaluation criteria are as follows.

[0295] (Good) Almost no residual organic matter was found (800-4000cm －1 The maximum absorption at is less than 0.1).

[0296] (Slightly better) Residual organic matter was confirmed (800-4000cm －1 The maximum absorption at is greater than 0.1 and less than 0.2).

[0297] (Bad) Residual organic matter was confirmed (800-4000cm －1 The maximum absorption at is greater than 0.2).

[0298] Table 1 also shows the results of the evaluation tests conducted as described above.

[0299] The above evaluation results show that the protective layer of the protective sheet of the example can protect the protected surface and can be removed relatively easily with water.

[0300] Furthermore, the protective layer of the protective sheet of the example contains the above-mentioned liquid component in addition to the above-mentioned solid hydrophilic polymer, and therefore has good adhesion to the protection surface of the protection object and good processability (performance in suppressing the occurrence of microcracks).

[0301] Industrial Applicability

[0302] The protective sheet of the present invention is preferably used for manufacturing a semiconductor device including a semiconductor integrated circuit or the like, for example.

[0303] Description of Reference Numerals

[0304] 1: protective sheet; 11: protective layer; 11': small piece of protective layer; 15: release liner; 20: dicing tape; 21: substrate layer; 22: adhesive layer; 30: chip bonding sheet; 50: dicing chip bonding film; W: semiconductor wafer; X: semiconductor chip; B: back grinding tape.

Claims

1. A protective sheet comprising: a protective layer which is removed by a liquid containing water after protecting at least a portion of a surface of a protected object; The protective layer includes a solid hydrophilic polymer and a liquid compound having a hydrophilic group in its molecule.

2. The protective sheet according to claim 1, wherein: The liquid compound is water-soluble.

3. The protective sheet according to claim 1 or 2, wherein: The protective layer includes 1 part by mass or more and 60 parts by mass or less of the liquid compound based on 100 parts by mass of the hydrophilic polymer.

4. The protective sheet according to claim 1 or 2, wherein: The protective layer has a storage modulus E' at 70° C. of 0.1 GPa or less.

5. The protective sheet according to claim 1 or 2, wherein: When the protective layer is subjected to dynamic viscoelasticity measurement, the peak temperature of Tan δ (E" / E'), which is the ratio of the loss modulus E" to the storage modulus E', is lower than 70°C.

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