protective sheet

Abstract

To provide a protective sheet including a protective layer that is relatively easily removed by a water-containing liquid and has not only good adhesion to an object to be protected but also good processability.SOLUTION: The protective sheet includes a protective layer that is removed by a water-containing liquid after protecting at least a portion of the surface of an object to be protected. The protective layer includes a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in the molecule.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a protective sheet used in the manufacture of electronic components such as semiconductor integrated circuits. [Background technology]

[0002] Conventionally, protective sheets have been known that are used to protect at least a portion of the surface of an object to be protected, for example, in the manufacture of semiconductor devices. The object to be protected by this type of protective sheet is, for example, a substrate such as a semiconductor wafer. This type of protective sheet is used by being attached to at least a portion of the surface of the object to be protected during the manufacturing process of the semiconductor device.

[0003] Generally, a method for manufacturing a semiconductor device includes a front-end process of forming a circuit surface on one side of a disk-shaped bare wafer using highly integrated electronic circuits, and a back-end process of cutting semiconductor chips from the semiconductor wafer with the circuit surface formed thereon. In the back-end process, a dicing tape having a base layer and an adhesive layer, a die bond sheet laminated on the dicing tape and adhered to the semiconductor wafer, and the above-mentioned protective sheet are used.

[0004] For details, the post-processing is a step of protecting the circuit surface of the disk-shaped semiconductor wafer by covering it with the protective sheet; a mounting step of placing a surface of the semiconductor wafer (a surface on which circuit components are not arranged) on a die bond sheet on a dicing tape and fixing the semiconductor wafer to the dicing tape via the die bond sheet; a dicing step of obtaining a large number of semiconductor chips (dies) by dividing the semiconductor wafer and the die bond sheet; an expanding process in which the dicing tape is stretched in the radial direction of the semiconductor wafer to widen the gap between adjacent semiconductor chips (dies); a pick-up step of peeling the die bond sheet and the dicing tape from each other to remove the semiconductor chips with the diced die bond sheet attached thereto; a die bonding step of bonding the semiconductor chip with the diced die bond sheet attached to an adherend via the die bond sheet; and a curing step of subjecting the die bond sheet to a thermal curing treatment. A semiconductor device is manufactured through, for example, these steps.

[0005] As the above-mentioned protective sheet, for example, a protective sheet that is attached to a surface (protected surface) of a semiconductor wafer or the like and then removed in order to prevent deposition material from adhering to the surface (protected surface) during a coating formation process by vapor deposition or the like is known (e.g., Patent Document 1).

[0006] The protective sheet described in Patent Document 1 has a resin composition containing an oxyalkylene group-containing polyvinyl alcohol-based resin with a degree of saponification 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 with relatively low-temperature water after protecting a portion of the surface of a substrate such as a semiconductor wafer. Furthermore, the resin composition of the protective sheet described in Patent Document 1 contains the above-mentioned polyvinyl alcohol-based resin and can therefore adhere appropriately to the surface to be protected. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-161735 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the resin composition of the protective sheet described in Patent Document 1 can adhere appropriately to the object to be protected, it has the problem that its processability is not necessarily good because it simply contains a polyvinyl alcohol resin and additives, etc. Specifically, when processing is performed such as cutting a resin composition formed into a sheet into a protective layer of a desired size, there is a problem that the processability is not necessarily good, such as the tendency for microcracks to occur in the portions of the protective layer that are subjected to the cutting force. As described above, the protective layer formed from the resin composition of the protective sheet described in Patent Document 1 can be removed relatively easily with a liquid containing water and has adequate adhesion to the object to be protected, but has the problem that its processability is not necessarily good.

[0009] In contrast, protective sheets that have a protective layer that can be removed relatively easily with a liquid containing water, that has good adhesion to the object to be protected, and that is also easy to process have not yet been fully studied.

[0010] Therefore, an object of the present invention is to provide a protective sheet that is provided with a protective layer that can be removed relatively easily with a liquid containing water, has good adhesion to the object to be protected, and also has good processability. [Means for solving the problem]

[0011] In order to solve the above problems, a protective sheet according to the present invention includes a protective layer that is removed by a liquid containing water after protecting at least a part of the surface of an object to be protected, The protective layer contains a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in the molecule. [Effects of the Invention]

[0012] The protective sheet according to the present invention is provided with a protective layer that can be removed relatively easily with a liquid containing water, has good adhesion to the object to be protected, and also has good processability. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view of an example of a protective sheet according to an embodiment of the present invention cut in the thickness direction. [Figure 2A] 5A and 5B are schematic cross-sectional views illustrating an example of a wetting step in a manufacturing method for an electronic component device. [Figure 2B] 5A and 5B are schematic cross-sectional views illustrating an example of a protection step in the manufacturing method of an electronic component device. [Figure 2C] FIG. 10 is a schematic cross-sectional view showing an example of a state after a protection step in the manufacturing method of an electronic component device. [Figure 2D] 10 is a schematic cross-sectional view showing an example of a removal step in a manufacturing method for an electronic component device (a schematic cross-sectional view showing an example of a state in which a protective layer is removed from a surface to be protected of an object to be protected by a liquid containing water). FIG. [Figure 3A] FIG. 2 is a cross-sectional view of an example of a dicing tape cut in the thickness direction. [Figure 3B] FIG. 2 is a cross-sectional view of an example of a dicing die bond film cut in the thickness direction. [Figure 4A] 5 is a schematic cross-sectional view showing a state after a mounting step and a protection step in the first example of the method for manufacturing a semiconductor device have been performed. [Figure 4B] 5 is a schematic cross-sectional view showing a state during a blade dicing process in the first example of the method for manufacturing a semiconductor device. FIG. [Figure 4C] FIG. 4 is a schematic cross-sectional view showing a state after a blade dicing process is performed in the first example of the method for manufacturing a semiconductor device. [Figure 4D] 5A to 5C are schematic cross-sectional views illustrating a removal step in the first example of the method for manufacturing a semiconductor device. [Figure 4E] 5A and 5B are schematic cross-sectional views illustrating a pickup step in the first example of the method for manufacturing a semiconductor device. [Figure 4F] 5A to 5C are schematic cross-sectional views illustrating a bonding step in the first example of the method for manufacturing a semiconductor device. [Figure 5A] 10 is a schematic cross-sectional view showing a state of a semiconductor wafer after half-cut processing in a second example of a method for manufacturing a semiconductor device. [Figure 5B] FIG. 10 is a schematic cross-sectional view showing a state after back grinding in the second example of the method for manufacturing a semiconductor device. [Figure 5C] 10A and 10B are schematic cross-sectional views illustrating a mounting step in a second example of a method for manufacturing a semiconductor device. [Figure 5D] 5A and 5B are schematic cross-sectional views illustrating an expanding step in the second example of the method for manufacturing a semiconductor device. [Figure 5E] 10 is a schematic cross-sectional view showing a modified example of the state of the semiconductor wafer after half-cut processing in the second example of the manufacturing method of the semiconductor device. [Figure 5F] FIG. 10 is a schematic cross-sectional view showing a modified example of the state after back grinding in the second example of the method for manufacturing a semiconductor device. [Figure 5G] 10A and 10B are schematic cross-sectional views illustrating a modified example of the mounting step in the second example of the method for manufacturing a semiconductor device. [Figure 6A] 10A and 10B are schematic cross-sectional views illustrating a stealth processing step in a third example of a method for manufacturing a semiconductor device. [Figure 6B] FIG. 11 is a schematic cross-sectional view showing a state after a stealth processing step in the third example of the method for manufacturing a semiconductor device. [Figure 6C] 10A and 10B are schematic cross-sectional views illustrating an expanding step in a third example of a method for manufacturing a semiconductor device. [Figure 6D] 10A and 10B are schematic cross-sectional views illustrating a removal step in a third example of a method for manufacturing a semiconductor device. [Figure 6E] FIG. 10 is a schematic cross-sectional view showing a modified example of the state before back grinding in the second example of the method for manufacturing a semiconductor device. [Figure 6F] FIG. 10 is a schematic cross-sectional view showing a modified example of the state after back grinding in the second example of the method for manufacturing a semiconductor device. [Figure 6G] 10A and 10B are schematic cross-sectional views illustrating a modified example of the mounting step in the second example of the method for manufacturing a semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the protective sheet according to the present invention will be described with reference to the drawings. Note that, since each figure in the drawings is a schematic view, the aspect ratio between each figure and the actual product is not necessarily the same.

[0015] 1, protective sheet 1 of this embodiment includes protective layer 11 that protects at least a portion of the surface of an object to be protected and that is at least partially dissolved and removed from the surface of the object to be protected upon contact with a liquid containing water. Protective layer 11 also contains a solid hydrophilic polymer and a liquid compound containing hydrophilic groups in its molecule. With this configuration, protective layer 11 of protective sheet 1 of this embodiment can be removed relatively easily with a liquid containing water, and not only does it have good adhesion to the object to be protected, but it also has good processability.

[0016] [Release liner for protective sheet] 1, the protective sheet 1 may include two release liners 15 arranged to sandwich the protective layer 11. The surface of the release liner 15 that contacts the protective layer 11 may be release-treated.

[0017] 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.

[0018] [Protective layer of protective sheet] The protective layer 11 is used, for example, to temporarily protect the surface to be protected (hereinafter also referred to as the surface to be protected) of the object to be protected. By overlaying the protective layer 11 on the surface to be protected, it is possible to prevent foreign matter from adhering to the surface to be protected until the protective layer 11 overlaying the surface to be protected is removed.

[0019] The object to be protected may be, for example, a substrate that constitutes an electronic component device such as a semiconductor device, etc. The substrate may be, for example, a circuit board such as a semiconductor wafer W.

[0020] For example, when the protective layer 11 is attached to the surface (circuit surface) of a substrate (semiconductor wafer) to be protected and then diced together with the substrate (semiconductor wafer), the protective layer 11 can prevent foreign matter such as debris that may be generated during dicing from adhering to the surface (circuit surface) to be protected, thereby protecting the surface (circuit surface).

[0021] The protective layer 11 has flexibility that allows it to be deformed by a relatively weak force, and also has adhesiveness that allows it to adhere closely to the surface of the substrate to be protected, for example.

[0022] The protective layer 11 may have physical properties that allow it to be diced into small pieces by being stretched in the planar direction. Protective layer 11 having such physical properties is suitable for use in manufacturing electronic component devices through a stealth processing step using a stealth dicing device, which will be described later. Similarly, it is suitable for use in manufacturing electronic component devices through a DBG process (described in detail later). The protective layer 11 does not need to have the above physical properties, since it can also be suitably used when manufacturing electronic component devices through a blade dicing process (described in detail later).

[0023] In the protective sheet 1, the thickness of the protective layer 11 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. Alternatively, such a thickness may be 40 μm or less. Note that when the protective layer 11 is a laminate, the above thickness is the total thickness of the laminate.

[0024] In this embodiment, the hydrophilic polymer contained in the protective layer 11 is solid at room temperature. On the other hand, the liquid compound containing a hydrophilic group in the molecule contained in the protective layer 11 is liquid at room temperature. Hereinafter, the liquid compound containing a hydrophilic group in the molecule may be simply referred to as a "liquid component."

[0025] 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 liquid, it is determined to be solid. Viscosity is measured using an E-type viscometer (for example, Toki Sangyo Co., Ltd., product name "TV-35") at 25°C and 20 rpm. To confirm the state (solid or liquid) of each component contained in the protective layer 11, a small amount of each component can be extracted from the protective layer 11 and the molecular structure of each component can be examined by, for example, infrared absorption spectroscopy (IR). If the component is a polymer compound, the molecular weight of the polymer compound can be further examined by gel permeation chromatography (GPC). The compound identified by these analytical methods can then be purchased separately and its viscosity measured as described above to confirm the state (solid or liquid) of each component.

[0026] The hydrophilic polymer has a hydrophilic group in the molecule, which may be at least one selected from the group consisting of a hydroxy group, a carboxy group (including a salt state), a sulfonic acid group (including a salt state), a pyrrolidone group, an amine-containing group (including a quaternary ammonium cation state), and a polyoxyethylene group. When the hydrophilic polymer contains, in particular, a hydroxy group as a hydrophilic group in the molecule, the protective layer 11 can adhere more adequately to the surface to be protected of the object to be protected.

[0027] For example, the protective layer 11 includes a hydrophilic polymer having a main chain and multiple side chains in the molecule as the hydrophilic polymer, and each of the multiple side chains has at least one of an ester group or a hydrophilic group, and the hydrophilic group may be a hydroxy group or a carboxy group.

[0028] The main chain of the hydrophilic polymer is a covalently bonded chain formed by, for example, a radical polymerization reaction, such as a polymerization reaction of vinyl acetate, alkyl (meth)acrylate ((meth)acrylic acid alkyl ester), hydroxyalkyl (meth)acrylate ((meth)acrylic acid hydroxyalkyl ester), (meth)acrylic acid, or N-vinylpyrrolidone.

[0029] Each of the multiple side chains in the hydrophilic polymer contains at least one of a hydrophilic group and an ester group. For example, among the many side chains contained in the hydrophilic polymer, some side chains have hydrophilic groups and others have ester groups. The hydrophilic group is, for example, at least one of a hydroxy group and a carboxy group. The ester group is represented by -C(=O)-O-. The side chain may have an atomic arrangement of ester groups, -C(=O)-O-, or an atomic arrangement of ester groups, -O-(C=O)-, from the main chain to the end of the side chain.

[0030] In each side chain containing a hydrophilic group, the hydrophilic group may be located at the terminal portion of the side chain or at the center portion of the side chain. The hydrophilic group in the side chain is preferably located at the terminal portion of the side chain. The hydrophilic group located at the terminal portion of the side chain may be bonded to the main chain via an ester group. For example, the ester group, alkyl group, and hydrophilic group may be arranged in this order from the main chain to the terminal of the side chain.

[0031] In a side chain containing an ester group, the ester group is preferably located in the center of the side chain. Preferably, in the side chain, an alkyl group having 1 to 4 carbon atoms is bonded to the main chain via the ester group.

[0032] Examples of the hydrophilic polymer include polyvinyl alcohol (PVA) obtained by hydrolyzing part of the ester bond in a vinyl acetate polymer, polyvinylpyrrolidone (PVP), water-soluble polyester polymer (PES) having a sulfonic acid group or a carboxy group in the molecule, polyethylene oxide (PEO) (e.g., molecular weight of 50,000 or more), polyacrylic acid, and polyvinylacetamide.

[0033] The hydrophilic polymer is preferably water-soluble. Whether the hydrophilic polymer is water-soluble can be confirmed, for example, as follows: When a thin film (thickness 50 μm or less) of the hydrophilic polymer is attached to a bare silicon wafer and immersed in water at 25° C. or 60° C., if the thin film dissolves completely (no residue remains on the wafer) at least at either temperature, the hydrophilic polymer is water-soluble.

[0034] The hydrophilic polymer is preferably at least one selected from the group consisting of polyvinyl alcohol, water-soluble polyester polymer, and polyethylene oxide.

[0035] When the hydrophilic polymer is polyvinyl alcohol (PVA), the degree of saponification (mol %) of the polyvinyl alcohol may be 50 or more and 100 or less. The degree of saponification of polyvinyl alcohol is preferably 55 or more, more preferably 60 or more, and even more preferably 65 or more. As the degree of saponification of polyvinyl alcohol increases, the protective layer 11 has higher hydrophilicity. Therefore, the protective layer 11 can be more easily removed with a liquid containing water. On the other hand, in order to further improve adhesion to objects to be protected such as substrates, the degree of saponification of polyvinyl alcohol is preferably 98 or less, more preferably 90 or less, and even more preferably 85 or less.

[0036] <Method and conditions for measuring the degree of saponification> The above saponification degree was measured by proton magnetic resonance spectroscopy ( 1 H MNR). When the protective layer 11 contains components other than PVA, the measurement is carried out after performing a separation and extraction process for PVA by methanol extraction or the like to avoid overlapping of peaks in the measurement chart. Analyzer: FT-NMR (For example, "AVANCEIII-400" manufactured by Bruker Biospin) Observation frequency: 400MHz (1H) Measurement solvent: deuterated water or deuterated dimethyl sulfoxide (deuterated DMSO) Measurement temperature: 80℃ Chemical shift standard: External standard TSP-d4 (0.00ppm) (when measuring heavy water) : Measurement solvent (2.50 ppm) (when measuring deuterated DMSO)

[0037] <Calculation of saponification degree> The degree of saponification is calculated using the following formula based on the peaks derived from the methylene groups of the vinyl alcohol unit (VOH) (heavy water: 2.0 to 1.1 ppm, heavy DMSO: 1.9 to 1.0 ppm) and the peaks derived from the acetyl groups of the vinyl acetate unit (VAc) (heavy water: around 2.1 ppm, heavy DMSO: around 2.0 ppm). In the formula, VOH (-CH-) is the intensity of the peak derived from the methylene groups of the vinyl alcohol unit (VOH), and VAc (CHCO-) ​​is the intensity of the peak derived from the acetyl groups of the vinyl acetate unit (VAc).

number

[0038] The average degree of polymerization of the polyvinyl alcohol is preferably 100 or more, more preferably 200 or more. The average degree of polymerization is preferably 1200 or less, more preferably 1000 or less, and even more preferably 800 or less. When the average degree of polymerization of polyvinyl alcohol is 100 or more, the protective layer 11 can be more easily formed. 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 the polyvinyl alcohol is increased, and the protective layer 11 can be more easily dissolved in a liquid containing water. In addition, the adhesiveness of the protective layer 11 to the object to be protected can be improved.

[0039] The average degree of polymerization is determined by the following measurement method and conditions. <Method and conditions for measuring the average degree of polymerization> ·Analytical equipment: Gel permeation chromatography analytical equipment (For example, Agilent's instrument name "1260Infinity") Column: TSKgel G6000PWXL and TSKgel G3000PWXL (Tosoh Corporation, serial connection) Column temperature: 40℃ Eluent: 0.2M aqueous sodium nitrate solution ·Flow rate: 0.8mL / min ·Injection volume: 100μL Detector: Differential Refractometer (RI) Standard samples: PEG standard sample and PVA standard sample The mass-average molecular weight Mw of the sample (PVA) and the PVA standard sample with a known average degree of polymerization are calculated by GPC measurement using a PEG standard sample. A calibration curve is created from the average degree of polymerization of the PVA standard sample and the calculated mass-average molecular weight Mw of the PVA standard sample. Using this calibration curve, the average degree of polymerization of the sample (PVA) is calculated from the mass-average molecular weight Mw of the sample (PVA).

[0040] The water-soluble polyester polymer (PES) has a polycarboxylic acid residue and a polyol residue. The water-soluble polyester is, for example, a polymerization product of a monomer component containing a polycarboxylic acid component and a polyol component. The water-soluble polyester polymer may further have at least one of an anionic hydrophilic group, a cationic hydrophilic group, or a nonionic hydrophilic group in the molecule. Examples of the anionic hydrophilic group include a sulfonic acid group (including a salt state) and a carboxy group (including a salt state). Examples of the cationic hydrophilic group include an amine-containing group. Examples of the nonionic hydrophilic group include a polyoxyethylene group. Whether the water-soluble polyester has water solubility can be determined based on common technical knowledge.

[0041] The mass-average molecular weight Mw of the water-soluble polyester polymer (PES) is preferably 40,000 (forty thousand) or less. By having a mass-average molecular weight Mw of 40,000 or less, the water-soluble polyester polymer can have a sufficiently low softening point. This can improve the adhesion of the protective layer 11 to the substrate (such as a semiconductor wafer). Furthermore, the protective layer 11 can be more easily removed from the surface of the object to be protected using a liquid containing water.

[0042] The polyethylene oxide (PEO) has a polyoxyethylene group as a hydrophilic group in the molecule. The mass-average molecular weight Mw of the polyethylene oxide (PEO) is preferably 1,000,000 (1,000,000) or less. By having a mass-average molecular weight Mw of 1,000,000 or less, the polyethylene oxide (PEO) can have a sufficiently low softening point. This can improve the adhesion of the protective layer 11 to the substrate (such as a semiconductor wafer). Furthermore, the protective layer 11 can be removed from the surface of the object to be protected more efficiently in a shorter time using a liquid containing water.

[0043] The polyacrylic acid has a carboxy 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 units of the acrylic acid monomer or the structural units of the methacrylic acid monomer to the total structural units is 90 mass% or more. The molecular weight of the polyacrylic acid may be, for example, 1,000 or more and 5,000,000 or less. The polyacrylic acid may be in the form of a salt such as a sodium salt, a potassium salt, an ammonium salt, etc. In other words, the term "polyacrylic acid" includes polyacrylic acid salts such as sodium polyacrylate.

[0044] The polyvinylacetamide has an amine-containing group as a hydrophilic group in the molecule. Specifically, the amine-containing group is represented by (—NH—CO—). The polyvinylacetamide is a polymer of N-vinylacetamide monomer.

[0045] In this embodiment, the liquid component is a liquid compound containing a hydrophilic group in the molecule, such as a hydroxy group, a carboxy group (including a salt state), a sulfonic acid group (including a salt state), a pyrrolidone group, an amine-containing group (including a quaternary ammonium cation state), or a polyoxyethylene group.

[0046] The liquid component may be a low molecular weight compound or a high molecular weight compound as long as it is liquid at room temperature (25° C.). Examples of the liquid component include polyethylene glycol that is liquid at room temperature, acrylic copolymer that is liquid at room temperature, ether-containing compound that is liquid at room temperature, polyoxyethylene polyoxypropylene glycol that is liquid at room temperature, polycation polymer that is liquid at room temperature, hydrophilic group-containing monomer that is liquid at room temperature, silane coupling agent that is liquid at room temperature, surfactant that is liquid at room temperature, and high-boiling point compound that is liquid at room temperature.

[0047] An example of polyethylene glycol that is liquid at room temperature is polyethylene glycol having an average molecular weight of 600 or less. For example, the melting point of polyethylene glycol (PEG600) with an average molecular weight of 600 is between 17°C and 22°C, so PEG600 is liquid at room temperature (25°C). Polyethylene glycol having an average molecular weight of 600 or less is water-soluble.

[0048] The acrylic copolymer that is liquid at room temperature has, for example, at least a carboxy group as a hydrophilic group, and at least a structural unit of an alkyl (meth)acrylate monomer and a structural unit of a carboxy group-containing (meth)acrylic monomer in the molecule. The mass average molecular weight of such an acrylic copolymer is, for example, 10,000 or less (e.g., about 2,000), and the acid value is about 70 mgKOH / g. An example of a product containing such an acrylic copolymer is "ARUFON 3510" (manufactured by Toagosei Co., Ltd.). Note that such an acrylic copolymer is water-soluble. The acrylic copolymer that is liquid at room temperature is, for example, a water-soluble acrylic graft polymer having a hydrophilic group (polyoxyethylene chain) in the side chain. The mass average molecular weight of such an acrylic copolymer is, for example, about 70,000, and the glass transition temperature Tg is about -40°C. Examples of products containing such an acrylic copolymer include the product name "Marproof HP Series" (manufactured by NOF Corporation).

[0049] Ether-containing compounds that are liquid at room temperature have a polar portion and a non-polar portion in the molecule. Examples of products containing such ether-containing compounds include the "Sofval P Series" (manufactured by NOF Corporation).

[0050] 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 "Epane Series" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0051] A polycationic polymer that is liquid at room temperature is obtained, for example, by polymerizing at least an allylic amine (diallylamine), and therefore has an amine-containing cyclic structure in the side chain portion. The amine in the side chain portion may be, for example, a secondary amine, a tertiary amine, or a quaternary ammonium salt. The polycationic polymer may have, for example, a sulfonic acid group in the main chain. Examples of products containing such polycationic polymers include the "PAS series" (manufactured by Nittobo Medical Co., Ltd.). A polycationic polymer that is liquid at room temperature is represented, for example, by the following general formula (1): In general formula (1), x is a secondary amine, a tertiary amine, or a quaternary ammonium salt. m may be 0. n is an integer of 1 or greater, and may be, for example, 1,000 or less. [ka]

[0052] Examples of hydrophilic group-containing monomers that are liquid at room temperature include (meth)acrylic monomers having a (meth)acrylic acid structure or a (meth)acrylate structure in the molecule. Such (meth)acrylic monomers contain a carboxyl group or an ester bond (ester group) as a hydrophilic group in the molecule. This type of (meth)acrylic monomer is commercially available (for example, the "Light Ester" series and the "Light Acrylate" series manufactured by Kyoeisha Chemical Co., Ltd.).

[0053] Silane coupling agents that are liquid at room temperature have an alkoxysilane structure in the molecule as a hydrophilic group. Examples of the silane coupling agent include silane coupling agents containing a vinyl group, an epoxy group, a styryl group, a (meth)acrylic group, an amino group, an isocyanate group, or an acid anhydride in the molecule. Furthermore, when classified by the functional group bonded to silicon (Si), the silane coupling agent may be a trialkoxysilane type, a methyldialkoxysilane type, etc. The alkoxy group may be a methoxy group or an ethoxy group. As these silane coupling agents, products such as "KBM series" (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used.

[0054] Surfactants that are liquid at room temperature contain anionic hydrophilic groups, cationic hydrophilic groups, or nonionic hydrophilic groups (such as polyoxyethylene chains) in the molecule as hydrophilic groups. When the surfactant that is liquid at room temperature is a polymer compound, the hydrophilic group may be an acrylonitrile group or an ester bond. The chemical names of surfactants that are liquid at room temperature and products containing these surfactants are explained below.

[0055] The liquid surfactant is, for example, an alkyltrimethyl or alkyldimethylbenzyl quaternary ammonium salt cationic surfactant. The alkyl moiety is, for example, a lauryl group, a palmityl group, a stearyl group, or a behenyl group. Such liquid surfactants are included, for example, in the "Nissan Cation" series (manufactured by NOF Corporation). The liquid surfactant is, for example, an acetate salt of an aliphatic amine (laurylamine or stearylamine). Such surfactants are included in, for example, the "Nissan Cation" series (manufactured by NOF Corporation).

[0056] The liquid surfactant is, for example, polyoxyethylene lauryl ether sulfate sodium salt, which is included in, for example, the product name "Trax" series (manufactured by NOF Corporation).

[0057] The liquid surfactant is, for example, a fatty acid amide ether sulfate sodium salt, and such surfactants are included in, for example, the "Sunamide" series (manufactured by NOF Corporation).

[0058] The liquid surfactant is, for example, fatty acid sodium methyl taurate, which is included in, for example, the "Diapon" series (manufactured by NOF Corporation).

[0059] The liquid surfactant is, for example, a polyoxyalkylene alkyl ether such as a polyoxyethylene branched alkyl ether, and such surfactants are included in, for example, the product name "Dispanol" series (manufactured by NOF Corporation).

[0060] The liquid surfactant is, for example, an aminoacetic acid betaine-type amphoteric surfactant such as fatty alkyldimethyl-aminoacetic acid betaine or fatty acid-amidopropyldimethyl-aminoacetic acid betaine. Such surfactants are included, for example, in the product name "Nissan Anon" series (manufactured by NOF Corporation).

[0061] The liquid surfactant is, for example, polyoxyethylene alkylamine, which is included in the "Nymeen" series (manufactured by NOF Corporation).

[0062] A high-boiling 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 such a compound may be lower than 250°C. The molecular weight of the high-boiling compound that is liquid at room temperature is, for example, 200 or less, and preferably 150 or less. Examples of high-boiling compounds that are liquid at room temperature include monohydric alcohols such as butanol and isobutyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, and glycerin; esters such as propyl acetate, isobutyl acetate, butyl acetate, and ethyl lactate; ketones such as methyl isobutyl ketone (MIBK) and cyclohexanone; glycol monoethers such as ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and 1-methoxy-2-propanol; glycol diethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; and nitrogen-containing organic compounds such as N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP). As the high-boiling compound that is liquid at room temperature, diethylene glycol, glycerin, N-methyl-2-pyrrolidone, or the like is preferred.

[0063] 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 more easily removed with a liquid containing water.

[0064] The liquid component is preferably a non-volatile compound, regardless of its molecular structure. Compounds with a vapor pressure of 2.5 hPa or less at 20°C are considered to be non-volatile.

[0065] The protective layer 11 has only to have a predetermined level of hydrophilicity or more when removed by a liquid containing water. When the protective layer 11 has a predetermined level of hydrophilicity or more, typically, at least a portion of the protective layer 11 dissolves in a liquid containing water.

[0066] The water absorption rate of the protective layer 11 is preferably 2.0% by mass or more when removed by a liquid containing water. This makes the protective layer 11 more easily soluble in a liquid containing water. The water absorption rate can be increased, for example, by increasing the content of hydrophilic groups in the hydrophilic polymer or by increasing the content of liquid components in the protective layer 11. The water absorption rate of the protective layer 11 may be, for example, 10.0% by mass or less.

[0067] The water absorption of the protective layer 11 is determined from measurements using coulometric titration according to the Karl Fischer method. Specifically, a test sample is placed in a steady state at 23°C and 50% RH, and heated at 150°C for 3 minutes using a moisture vaporizer, while measuring the amount of vaporized water. The water absorption is determined from the ratio of the measured amount of water to the mass of the heated test sample.

[0068] In the protective layer 11, the amount of the liquid component per 100 parts by mass of the hydrophilic polymer is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, which improves processability of the protective layer 11, such that microcracks are less likely to occur when subjected to shearing force during cutting, and also allows the protective layer 11 to adhere more sufficiently to the object to be protected. The amount of the liquid component per 100 parts by mass of the hydrophilic polymer may be 60 parts by mass or less, or may be 40 parts by mass or less. When the protective layer 11 does not contain an excessive amount of the liquid component, the moldability when producing the protective layer 11 is improved.

[0069] In this embodiment, the adhesion of the protective layer 11 to the object to be protected is indicated by the peeling force when peeling the protective layer 11 from, for example, a bare silicon wafer as a substrate. The peeling force of the protective layer 11 may be 100 [N / 100 mm] or less, or may be 80 N / 100 mm or less. The peeling force may be 0.2 [N / 100 mm] or more.

[0070] The peel force is measured under the following conditions. To measure the peel strength of one surface of the protective layer 11 (the surface to be attached to a bare silicon wafer), a measurement sample is prepared as follows. First, at 25°C, a backing tape is attached to the surface of the protective layer 11 opposite to the one surface using a hand roller. Next, the measurement sample is processed to a width of 100 mm, and a bare wafer is attached to the one surface of the protective layer 11. The attachment is performed under conditions of 90°C and 10 mm / sec. Then, in an atmosphere of 23°C, the protective layer 11 together with the backing tape is peeled from the bare wafer at a peel angle of 180° and a peel rate of 300 mm / min, and the peel strength is measured. Note that an Autograph (manufactured by Shimadzu Corporation), for example, can be used as a measuring device.

[0071] When the protective layer 11 is subjected to dynamic viscoelasticity measurement, the storage modulus E' of the protective layer at 70°C may be 0.1 GPa or less (100 MPa or less). Such a moderately small storage modulus E' allows the protective layer 11 to have better conformability when subjected to a deforming force. Furthermore, the wettability to the interface of the object to be protected is improved, which may result in better adhesion to the object to be protected. The storage modulus E' of the protective layer 11 at 70°C may be 0.01 GPa or more (10 MPa or more).

[0072] When the above protective layer 11 is subjected to dynamic viscoelasticity measurement, the temperature at which the loss modulus E" reaches its maximum value may be 35°C or lower. This allows the protective layer 11 and the object to be bonded together at a lower temperature and to be sufficiently adhered to each other. The temperature at which the loss modulus E" reaches its maximum value may be 5°C or higher.

[0073] When the protective layer 11 is subjected to dynamic viscoelasticity measurement, it is preferable that the peak temperature of Tan δ(E" / E'), which is the ratio of the loss modulus E" to the storage modulus E', is less than 70°C. This allows the protective layer 11 to have better conformability when subjected to a deforming force. In addition, the wettability to the interface of the object to be protected is improved, which can result in better adhesion to the object to be protected. Furthermore, since the protective layer 11 can be adhered to the object to be protected at a relatively low temperature, the protection step described below can be carried out at a relatively low temperature, which can further reduce the thermal energy cost for heating required in the protection step. 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 protective layer 11 can be easier to handle.

[0074] The dynamic viscoelasticity of the protective layer 11 is measured using a solid viscoelasticity measuring device in a tension mode under the following test conditions. Test sample thickness: 50 μm, Test sample width: 10mm, Chuck distance: 20mm, Heating rate: 10°C / min Test temperature: 0℃~120℃ Frequency: 1Hz The storage modulus E' and loss modulus E" are measured over time, and Tanδ is calculated over time using the formula Tanδ = E" / E'. A higher Tanδ indicates a higher viscosity. Tanδ forms a peak, and the temperature at which it reaches its apex is read. The storage modulus E' and peak Tanδ values ​​at 70°C are calculated by averaging three measurements.

[0075] The above-mentioned protective sheet 1 can be produced by a general method. For example, the protective layer 11 may be prepared by mixing the above-mentioned hydrophilic polymer, liquid component, and solvent by a conventional method, applying the mixture to the release liner 15, and then evaporating the solvent from the mixture.

[0076] The above-described protective sheet 1 is used, for example, by peeling off release liner 15 from protective layer 11 and attaching protective layer 11 to the surface to be protected of the object to be protected. Then, protective layer 11, which has protected the surface to be protected, is removed from the surface to be protected by a liquid containing water.

[0077] Next, a method for using the protective sheet 1 of this embodiment will be described. Specifically, the method will be described taking as an example a method for manufacturing an electronic component device using the protective sheet 1. In this example, the object to be protected is a substrate, which is a member constituting the electronic component device.

[0078] The electronic component device manufactured using the above-mentioned protective sheet 1 may be, for example, a semiconductor device such as a semiconductor integrated circuit equipped with a semiconductor chip, a device equipped with a system LSI having a complementary MOS (CMOS), or a device equipped with a device (MEMS Micro Electro Mechanical Systems) in which mechanical elements, sensors, actuators, or electronic circuits are integrated by microfabrication technology onto a single silicon substrate, glass substrate, organic material substrate, etc. The manufactured electronic component device may also be a device equipped with a wiring board.

[0079] In the manufacturing method for an electronic component device using the above-described protective sheet 1, as shown in FIG. 2B , one surface of the substrate S, the surface to be protected Sa, is protected by a protective layer 11. Note that a circuit component (described in detail later) may or may not be disposed on the surface to be protected Sa. In other words, the surface to be protected Sa of the substrate S may be, for example, a circuit surface on which a circuit is formed, or a non-circuit surface on which no circuit is formed.

[0080] The protective layer 11 may be formed on the surface Sa to be protected of the substrate S. For example, the protective layer 11 may be formed by applying a mixture of the above-mentioned hydrophilic polymer, liquid component, and solvent to the surface Sa to be protected of the substrate S, and then volatilizing the solvent. The formed protective layer 11 has good adhesion to the surface Sa to be protected of the substrate S, since it contains the above-mentioned hydrophilic polymer and liquid component.

[0081] There are no particular limitations on the material of the substrate S as long as it is plate-shaped. Examples of the substrate include a semiconductor wafer, a substrate that will constitute a sensor wafer such as a CMOS or MEMS, a pseudo wafer, or a wiring substrate.

[0082] A method for manufacturing an electronic component device using the above-mentioned protective sheet 1 includes the steps of: a step of protecting one surface to be protected of the substrate by overlaying the protective layer 11 of the protective sheet 1 described above on the surface to be protected (protection step); and a step (removal step) of removing the protective layer 11 overlapping the surface to be protected by bringing the protective layer 11 into contact with a liquid containing water. The details of the protective layer 11 are as described above.

[0083] In the above-described method for manufacturing an electronic component device, a step of increasing the humidity of the gas in contact with the surface Sa to be protected of the substrate S (wetting step) may be performed before the protecting step, as needed (see FIG. 2A). By performing the wetting step, the adhesion of the protective layer 11 to the surface Sa to be protected can be improved. The wetting step can be carried out, for example, by bringing a gas containing water vapor into contact with the surface to be protected, by spraying mist-like water onto the surface to be protected, or by applying water to the surface to be protected.

[0084] In the above-mentioned protection step, the protective layer 11 of the protective sheet 1 is superposed on the surface to be protected Sa of the substrate S. In the protection step, for example, the protective layer 11 is superposed on the surface of the substrate S on the side where at least one of the circuit wiring, sensor unit, and electrode unit is arranged as a circuit component. In the above-mentioned protection step, it is preferable to superpose the protective layer 11 on at least one surface of the substrate S so as to cover the circuit wiring, sensor unit, or electrode unit with the protective layer 11. Examples of the circuit component include circuit wiring, electrode units, or elements such as transistors, diodes, or sensor units (such as light-receiving sensors or vibration sensors).

[0085] In the above-mentioned method for manufacturing an electronic component device, if necessary, a step (e.g., a dicing step) may be carried out in which the stack of overlapping substrates S and protective layers 11 is divided into small pieces at intervals in the planar direction, as shown in Figure 2C, to produce multiple stacked small pieces of chips S' formed by dividing the substrate into small pieces and small pieces 11' of the protective layer.

[0086] In the removal step, as shown in Fig. 2D, the protective layer 11 overlapping the surface to be protected of the substrate S is removed by a liquid containing water. In the removal step, when the protective layer 11 is removed, the entire protective layer 11 may be dissolved in the liquid containing water, or only a part of the protective layer 11 may be dissolved.

[0087] A method for manufacturing a semiconductor device for manufacturing a semiconductor integrated circuit will be described in detail below with reference to the drawings as a specific example.

[0088] In a method for manufacturing a semiconductor device (electronic component device), for example, semiconductor chips X are cut out from a semiconductor wafer W having a circuit surface formed thereon, and a semiconductor device having the cut-out semiconductor chips X is assembled. In the method for manufacturing a semiconductor device described below, a semiconductor device is manufactured using at least the protective layer 11 of a protective sheet 1 and a dicing tape 20 (see FIG. 3A). The dicing tape 20 has a base layer 21 and an adhesive layer 22. These sheets and tapes are used as auxiliary tools for manufacturing a semiconductor device. It is also possible to use a dicing die bond film 50 in which a die bond sheet 30 is superimposed on the adhesive layer 22 of the dicing tape 20 (see FIG. 3B). Commercially available products can be used as the dicing tape 20 and the dicing die bond film 50.

[0089] Generally, a manufacturing method of a semiconductor device includes a front-end process of forming a circuit surface on one side of a bare wafer using highly integrated electronic circuits, and a back-end process of cutting out semiconductor chips X from the semiconductor wafer W on which the circuit surface has been formed and assembling them.

[0090] In a post-process, for example, a wafer (semiconductor wafer W) as a substrate on which a circuit surface is formed is diced into small semiconductor chips X (dies), and then the diced semiconductor chips X are bonded to an adherend, thereby assembling a semiconductor integrated circuit (semiconductor device).

[0091] Hereinafter, first to third examples of the method for manufacturing a semiconductor device will be described in detail. The drawings showing the manufacturing method of the first example are marked with "I." Similarly, the drawings showing the manufacturing method of the second and third examples are marked with "II" and "III," respectively.

[0092] "First Example of Semiconductor Device Manufacturing Method" The first example of the method for manufacturing a semiconductor device includes an assembly process in which semiconductor chips X are cut out from a semiconductor wafer W (substrate) on which a circuit surface is formed, and a semiconductor device having such semiconductor chips X is assembled. The assembly process includes a protection process of overlaying a protective layer 11 for protecting the circuit components on at least one surface of the semiconductor wafer W, which is a circuit surface on which any of the circuit components is formed, to protect the circuit surface (surface to be protected); a mounting step of attaching a semiconductor wafer W having circuit components formed on one side thereof to a dicing die bond film 50 (a die bond sheet 30 superimposed on a dicing tape 20) and fixing the semiconductor wafer W to the dicing die bond film 50; a peeling step, which is carried out as needed, of removing the release liner 15 by peeling between the protective layer 11 and the release liner 15; a step of cutting a laminate of the semiconductor wafer (W), the protective layer (11) and the die bond sheet (30) into small pieces at intervals in the surface direction, thereby producing a plurality of small pieces of a laminate in which the semiconductor chips (X) cut from the semiconductor wafer (W), the small pieces (11') of the protective layer and the small pieces (30') of the die bond sheet (30) are overlapped with each other; a removing step of removing each small piece 11' of the protective layer by bringing each small piece 11' of the protective layer overlapping the circuit surface of the semiconductor chip X into contact with a liquid including water; a pick-up step of peeling the dicing tape 20 and the die-bonding sheet piece 30' from each other to take out the semiconductor chip X with the die-bonding sheet piece 30' attached; and a bonding step of bonding the extracted semiconductor chip X to an adherend via the small piece 30' of the die-bonding sheet. When these steps are carried out, the above-described protective layer 11 and the dicing die bond film 50 having the dicing tape 20 are used as manufacturing aids.

[0093] In the manufacturing method of the first example, a blade dicing process is carried out as a process for producing a plurality of small pieces of the laminate. In the blade dicing process, the die bond sheet 30, the semiconductor wafer W, and the protective layer 11 are diced into small pieces by a dicing blade T or the like, and the semiconductor wafer W is diced into semiconductor chips X (dies).

[0094] The semiconductor wafer W is configured so that a plurality of semiconductor chips X can be obtained. More specifically, the semiconductor wafer W is configured so that a plurality of semiconductor chips X can be fabricated by being divided into small pieces at intervals in a plurality of directions along the surface (for example, directions along the surface that are perpendicular to each other), so that a plurality of semiconductor chips X can be fabricated. Furthermore, the semiconductor wafer W has, on one surface, a circuit surface on which at least one type of circuit component is arranged.

[0095] In recent years, with the further advancement of integration technology in the semiconductor industry, there has been a demand for thinner semiconductor chips (for example, thicknesses of 20 μm to 50 μm). When viewed from one side in the thickness direction, the shape of a semiconductor chip is, for example, rectangular, with a side length of, for example, 5 mm to 20 mm.

[0096] 4A, in the protection step, a protective layer 11 is superimposed on the circuit surface of the semiconductor wafer W. By superimposing the protective layer 11 on the circuit surface of the semiconductor wafer W, the circuit surface can be protected by the protective layer 11 until the protective layer 11 is removed. Therefore, it is possible to prevent dust and the like from adhering to the circuit surface of the semiconductor wafer W covered with the protective layer 11. For example, the protection step and the mounting step can be performed simultaneously as follows.

[0097] In the mounting step, a dicing ring R may first be attached to the adhesive layer 22 of the dicing tape 20, and then the dicing ring R may be fixed to a holder H of an expanding device. Then, as shown in FIG. 4A, the semiconductor wafer W, the protective layer 11, and the release liner 15 are attached at the same time to the die bond sheet 30 that is overlaid on the dicing tape 20. For example, the semiconductor wafer W is fixed to the die bond sheet 30 in this manner. 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 circuit surface.

[0098] When the release liner 15 is used as described above, a peeling step may be carried out in which the release liner 15 is removed by peeling the release liner 15 from the protective layer 11 .

[0099] In the blade dicing process, the semiconductor wafer W is diced, for example, as shown in Figures 4B and 4C. More specifically, the protective layer 11 and the semiconductor wafer W are cut to a predetermined size together with the die bond sheet 30 to form semiconductor chips X with die bond sheet pieces 30'. At this time, protective layer pieces 11' are also formed. The blade dicing process is performed in a conventional manner, for example, using a dicing blade T. In the blade dicing process, for example, a cutting method called full cut, in which the cut is made all the way to the die bond sheet 30, can be used. The dicing device used in the blade dicing process is not particularly limited, and conventionally known devices can be used. In the blade dicing process, foreign matter such as debris may be generated when the semiconductor wafer W is cut. At this time, the surface to be protected of the semiconductor wafer W is protected by the protective layer 11, so that the adhesion of foreign matter to the surface to be protected can be suppressed.

[0100] In the removal process, as shown in FIG. 4D, for example, a liquid containing water is brought into contact with the multiple 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. By removing the small pieces 11' of the protective layer in this manner, all of the small pieces 11' of the protective layer can be removed relatively easily, and the number of foreign matters adhering to the surfaces of the semiconductor chips can be reduced relatively easily using the liquid. In addition, the surfaces (protected surfaces) of the semiconductor chips X on which the small pieces 11' of the protective layer overlap can also be cleaned with the liquid.

[0101] In the removal step, the protective layer pieces 11' may be removed by dissolving all of the fragmented protective layer (the multiple protective layer pieces 11') in the liquid. Alternatively, the multiple protective layer pieces 11' may be removed by dissolving some of the components of the protective layer pieces 11' in the liquid and peeling off each of the pieces 11' from the semiconductor chip X, which has weakened its adhesion to the semiconductor chip X.

[0102] The water-containing liquid is not particularly limited as long as it is a liquid substance containing water, and 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, in addition to water, a component that dissolves in water. Examples of such components include water-soluble organic solvents. Examples of such water-soluble organic solvents include monohydric alcohols having four or fewer carbon atoms, such as methanol, ethanol, propanols such as isopropyl alcohol, and butanols such as t-butanol.

[0103] In the removal step in the first example, the protective layer pieces 11' may be immersed in the stirred liquid to bring the liquid into contact with the protective layer pieces 11'. Alternatively, liquid sprayed from a nozzle or the like may be brought into contact with the protective layer pieces 11'. 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.

[0104] For example, in the removal step, the liquid is sprayed toward the semiconductor chips X respectively attached to the small pieces 30' of the die bond sheet while rotating a disk-shaped stage supporting the dicing tape 20 from below in the circumferential direction. This makes it possible to remove the multiple small pieces 11' of the protective layer respectively overlapping the semiconductor chips X.

[0105] According to the first example method for manufacturing a semiconductor device, a protective layer 11 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 11 is removed.

[0106] In the pick-up process, as shown in FIG. 4E, the small piece 30′ of the die bond sheet to which the semiconductor chip X is attached is peeled off from the adhesive layer 22 of the dicing tape 20. More 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 bond sheet are held by a suction jig J.

[0107] When performing the pick-up process in this manner, it is necessary that the small piece 30' of the die bond sheet attached to the semiconductor chip X be easily peeled off from the adhesive layer 22 of the dicing tape 20. The above-described dicing tape 20 is designed to be able to exhibit this performance well. For example, the dicing tape 20 is configured so that, when irradiated with active energy rays (e.g., ultraviolet rays), the adhesive layer 22 hardens and the adhesive strength of the adhesive layer 22 decreases. Since the adhesive layer 22 hardens after irradiation, the adhesive strength of the adhesive layer 22 can be reduced, and therefore the semiconductor chip X and the small piece 30' of the die bond sheet can be relatively easily peeled off from the adhesive layer 22 after irradiation. Dicing tapes 20 configured in this way are commercially available.

[0108] In the bonding process, the semiconductor chip X with the die bond sheet piece 30' attached thereto is bonded to the adherend Z. In other words, the semiconductor chip X is bonded to the adherend such as a substrate or semiconductor chip X via the die bond sheet piece 30'. In the bonding process, as shown in FIG. 4F, a plurality of semiconductor chips X with the die bond sheet piece 30' attached thereto may be stacked. The adherend Z may be, for example, an interposer, a wiring circuit board, or a small piece of substrate (when small pieces of substrate are stacked and laminated).

[0109] In the first example, in order to protect the semiconductor chip X after the bonding step, a resin sealing step may be performed in which the semiconductor chip X is sealed (covered) with a thermosetting resin or the like.

[0110] Next, the second example will be described in detail. Note that the second example will not be described in the same manner as the first example. In the second example, unless otherwise specified, the same operations as in the first example can be performed.

[0111] "Second Example of Semiconductor Device Manufacturing Method" The manufacturing method of the semiconductor device of the second example differs from the first example mainly in that the semiconductor wafer W is divided into small pieces through a so-called DBG process, in which the thickness of the semiconductor wafer W is reduced after half-cutting the semiconductor wafer W. In the second example, grooves are formed in the semiconductor wafer W to process the semiconductor wafer W into chips (dies) by a fracturing process, and the semiconductor wafer W is further ground to reduce its thickness.

[0112] The second example of the manufacturing method of the semiconductor device includes, for example, a half-cut processing step of forming grooves on the circuit surface of the semiconductor wafer W for dividing the semiconductor wafer W into small pieces to produce a plurality of semiconductor chips X; a back-grinding process in which a surface of the semiconductor wafer W opposite to the circuit surface is ground to reduce the thickness of the semiconductor wafer W; a mounting step of attaching the thinned semiconductor wafer (W) to a die bond sheet (30) on a dicing tape (20) and fixing the semiconductor wafer (W) to the die bond sheet (30); an expanding step of expanding the dicing tape 20 to divide the semiconductor wafer W, the die bond sheet 30, 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 pick-up step of peeling the semiconductor chip X from the small piece 30' of the die bond sheet to take out the semiconductor chip X; and a bonding step of bonding the extracted semiconductor chip X to an adherend via the small piece 30' of the die bond sheet.

[0113] In the second example, with a wafer processing tape attached to the surface opposite to the surface to be protected of the semiconductor wafer W, dividing grooves for dividing the semiconductor wafer W into small pieces are formed. The grooves are formed in the semiconductor wafer W so as not to penetrate through in the thickness direction.

[0114] Next, as shown in FIG. 5A, for example, a backgrind tape B is superimposed on the circuit surface of the semiconductor wafer W on which the grooves are formed, and the surface to be protected (circuit surface) is protected by the backgrind tape B. Then, as shown in FIG. 5B, for example, with the backgrind tape B attached, a grinding process is performed on the surface of the semiconductor wafer W on which no circuit components are arranged. For example, the semiconductor wafer W is ground using a grinding pad (backgrinding process) until it reaches a predetermined thickness. The thickness of the semiconductor wafer W is reduced to the predetermined thickness by the grinding process.

[0115] Then, the ground surface of the semiconductor wafer W (the surface on which no circuit components are arranged) is attached to the die bond sheet 30 on the dicing tape 20, and a mounting step is carried out (see FIG. 5C).

[0116] Next, an expanding process is performed to divide the semiconductor wafer W and the protective layer 11 into small pieces. In the expanding process, as shown in FIG. 5D , with the semiconductor wafer W attached to the die bond sheet 30 on the dicing tape 20, the dicing tape 20 is stretched in the planar direction to increase the surface area of ​​the dicing tape 20. This divides the laminate of the protective layer 11, the semiconductor wafer W, and the die bond sheet 30 into small pieces, and the spacing between adjacent semiconductor chips X formed by the small pieces is increased in the planar direction. More specifically, 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 that it expands in the planar direction. This divides the semiconductor wafer W, the die bond sheet 30, and the protective layer 11 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 process). When the expanding step is performed at such a low temperature, it is necessary to cleave the protective layer 11 and the die bond sheet 30 into small pieces. The above-described protective layer 11 and die bond sheet 30 are each designed so as to be cleaved well at this time. Furthermore, in the expanding step, the dicing tape 20 may be stretched again under higher temperature conditions (for example, 10°C or higher and 25°C or lower) so as to increase the surface area of ​​the dicing tape 20. This allows the adjacent semiconductor chips X to be separated in the surface direction of the dicing tape 20, further increasing the kerf (gap) (room temperature expanding step).

[0117] Thereafter, by a removal step using a method similar to that described above, the small pieces 11' of the protective layer attached to the semiconductor chip X can be removed. Also, by a method similar to that described above, a pick-up step of taking out the semiconductor chip X and a bonding step of bonding the semiconductor chip X to an adherend can be performed.

[0118] In the second example, steps not specifically mentioned can be carried out in the same manner as the steps in the first example.

[0119] In the second example, as shown in Fig. 5E, when grinding the semiconductor wafer W using the backgrind tape B, a protective layer 11 may be placed between the backgrind tape B and the semiconductor wafer W. Even in this state, the grinding process (backgrinding) can be performed, and the semiconductor wafer W can be thinned to a desired thickness as shown in Fig. 5F. Thereafter, as shown in Fig. 5G, a mounting process can be performed with the backgrind tape B and the protective layer 11 stacked on the semiconductor wafer W.

[0120] Next, the third example will be described in detail. Note that for the third example, the same explanation as for the first or second example will not be repeated. In the third example, unless otherwise specified, the same operations as for the first or second example can be performed.

[0121] "Third Example of Semiconductor Device Manufacturing Method" The third example of the method for manufacturing a semiconductor device differs from the first or second example mainly in that a weak portion is formed inside the semiconductor wafer W and the semiconductor wafer W is divided into small semiconductor chips X along the weak portion.

[0122] The third example of the manufacturing method of the semiconductor device includes, for example, a mounting step of attaching the semiconductor wafer W having circuit components formed on both sides thereof to a dicing tape 20 and fixing the semiconductor wafer W to the dicing tape 20; a protection step of protecting the circuit surface by attaching a protection layer 11 to the exposed circuit surface of the semiconductor wafer W; a stealth processing step in which weak portions are formed inside the semiconductor wafer W with the protective layer 11 attached thereto by laser light, thereby preparing the semiconductor wafer W for dicing into semiconductor chips X (dies); an expanding step of expanding the dicing tape 20 to divide 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 pick-up step of peeling the semiconductor chip X from the adhesive layer 22 to remove the semiconductor chip X; and a bonding step of bonding the extracted semiconductor chip X to an adherend. When these steps are carried out, the above-mentioned protective layer 11 and dicing tape 20 are used as manufacturing aids.

[0123] In the third example, as shown in FIG. 5A, the die bond sheet 30 is not placed on the dicing tape 20, and the semiconductor wafer W is placed on the adhesive layer 22 of the dicing tape 20.

[0124] In the stealth processing step, weakened portions for dicing the semiconductor wafer W into semiconductor chips X are formed inside the semiconductor wafer W. The weakened portions are formed inside the semiconductor wafer W by irradiating the semiconductor wafer W with laser light L (see FIGS. 6A and 6B). The laser light L is irradiated onto the semiconductor wafer W from the dicing tape side, for example. The stealth processing step can be performed using, for example, a commercially available stealth dicing device. Before the mounting step, the semiconductor wafer W may be irradiated with laser light to form a weak portion inside the wafer.

[0125] In the expanding step, as shown in Fig. 6C, the dicing tape 20 is stretched in the planar direction so as to expand the area of ​​the dicing tape 20, thereby dividing the protective layer 11 into small pieces together with the semiconductor wafer W. More specifically, by stretching 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, as the semiconductor wafer W is divided into small semiconductor chips X, the protective layer 11 is also divided into small pieces.

[0126] The removal step of the third example can be carried out in the same manner as the removal step of the first example, as shown in FIG. 6D.

[0127] In the pick-up step of the third example, the semiconductor chip X is peeled off from the adhesive layer 22 of the dicing tape 20. When the pick-up step is performed in this manner, the semiconductor chip X is peeled off from the adhesive layer 22 of the dicing tape 20.

[0128] In the third example, the joining step can be carried out in the same manner as in the first or second example.

[0129] In the third example, steps not specifically mentioned can be carried out in the same manner as the steps in the first or second example.

[0130] In the third example, as shown in Fig. 6E, when grinding the semiconductor wafer W using the backgrind tape B, a protective layer 11 may be placed between the backgrind tape B and the semiconductor wafer W. Even in this state, the grinding process (backgrinding) can be performed, and the semiconductor wafer W can be thinned to a desired thickness as shown in Fig. 6F. Thereafter, as shown in Fig. 6G, a mounting process can be performed with the backgrind tape B, the protective layer 11, and the semiconductor wafer W stacked together.

[0131] The protective sheet of the present invention and the method for manufacturing an electronic component device using the protective sheet are as exemplified above, but the present invention is not limited to the protective sheet or manufacturing method exemplified above. That is, various forms used in general manufacturing methods of electronic component devices can be adopted within the scope that does not impair the effects of the present invention.

[0132] The matters disclosed by this specification include the following. (1) a protective layer that is removed by a liquid containing water after protecting at least a part of the surface of the object to be protected; The protective layer comprises a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in the molecule. (2) The protective sheet according to (1) above, wherein the liquid compound is water-soluble. (3) The protective sheet according to (1) or (2) above, wherein the protective layer contains the liquid compound in an amount of 1 part by mass or more and 60 parts by mass or less when the content of the hydrophilic polymer is 100 parts by mass. (4) The protective sheet according to any one of (1) to (3) above, wherein the protective layer has a storage modulus E' at 70°C of 0.1 GPa or less. (5) The protective sheet according to any one of (1) to (4) above, 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 less than 70°C. (6) The protective sheet according to any one of (1) to (5) above, wherein the hydrophilic polymer has a plurality of hydrophilic groups in the molecule, and the hydrophilic group is at least one selected from the group consisting of a hydroxy group, a carboxy group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, and a polyoxyethylene group. (7) 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, polyvinylpyrrolidone, water-soluble polyester polymer, polyethylene oxide, polyacrylic acid, and polyvinylacetamide. (8) The protective sheet according to any one of (1) to (7) above, wherein the liquid compound has a hydrophilic group in the molecule, and the hydrophilic group is at least one selected from the group consisting of a hydroxy group, a carboxy group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, and a polyoxyethylene group. [Example]

[0133] 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.

[0134] (Examples 1 to 4, Comparative Examples 1 and 2, Reference Example 1) The protective sheets of each of the Examples, Comparative Examples, and Reference Example 1 were produced as follows: Specifically, the following raw materials were prepared as the hydrophilic polymer and liquid component. The hydrophilic polymer and liquid components were dispersed in water, and then heated to 90°C to dissolve them, thereby preparing an aqueous PVA solution. This PVA aqueous solution was applied to a release liner (PET film, 50 μm thick). The release liner had a surface that had been treated with a silicone release agent, and the PVA aqueous solution was applied to this surface using an applicator. This was then dried at 110°C for 2 minutes, forming a 10 μm thick protective layer (film) on one side of the release liner. Details of the raw materials of the protective layer used in each example and comparative example are shown in Table 1 and below.

[0135] [Protective layer raw materials] Hydrophilic polymer: Polyvinyl alcohol (all of the following are water-soluble) 1) PVA-1: Degree of saponification: 82 (mol%), average degree of polymerization: 500 (Manufactured by Kuraray) 2) PVA-2: Degree of saponification: 65 (mol%), average degree of polymerization: 240 (Manufactured by Japan Vinyl Acetate & Poval Co., Ltd.) 3) PVA-3: Degree of saponification: 98 (mol%), average degree of polymerization: 1200 (Mitsubishi Chemical Corporation) Liquid ingredients (all water-soluble) 1) PEG300: Polyethylene glycol 300 (average molecular weight 300, commercially available product) Vapor pressure at 20°C: less than 2.0 hPa 2) PEG600: Polyethylene glycol 600 (average molecular weight 600, commercially available) Vapor pressure at 20°C: less than 2.0 hPa 3) Acrylic copolymer: Product name "ARUFON UC-3510" (manufactured by Toagosei Co., Ltd.) An acrylic copolymer having at least an alkyl (meth)acrylate structural unit and a carboxyl group-containing (meth)acrylate structural unit in the molecule. Mass average molecular weight: about 2000, acid value: about 70 [mgKOH / g] Vapor pressure at 20°C: less than 2.0 hPa 4) PEG400: Polyethylene glycol 400 (average molecular weight 400, commercially available) Vapor pressure at 20°C: less than 2.0 hPa

[0136] [Table 1]

[0137] The physical properties (dynamic viscoelasticity) of the protective sheets produced were measured as follows, and the performance of the protective sheets was also evaluated.

[0138] <Measurement of dynamic viscoelasticity of protective sheets> The dynamic viscoelasticity of the protection sheet was measured using a solid viscoelasticity measuring device (RSA3 manufactured by TA Instruments) according to the measurement conditions described above. The temperature at which the storage modulus E' and loss modulus E" reached their maximum at 70°C, and the temperature at which tan δ(E" / E') reached its peak were determined.

[0139] <Ease of creating protective layers (film formation)> The state of the film during production was visually observed and evaluated on a three-level scale: ◯ (good), fairly good (Δ), and poor (×).

[0140] <Processability (resistance to microcracks when cutting the protective layer)> When the protective layer was cut to a desired size, it was visually observed whether or not microcracks occurred. If no microcracks occurred, it was evaluated as ○ (good), and if microcracks occurred, it was evaluated as poor (×).

[0141] <Adhesion of the protective layer to the object to be protected> The peel strength between the protective layer and the bare silicon wafer was measured using the above-mentioned measurement method. If the peel strength of the protective layer to the bare silicon wafer was 0.2 N / 100 mm or more, it could be said that the adhesion was good.

[0142] <Removability of protective layer with water> To remove the protective layer, the laminate of the bare silicon wafer and the protective layer was immersed in water at 25°C for 30 seconds. The water used to remove the protective layer was then removed. Furthermore, the surface of the bare silicon wafer was analyzed using a Fourier transform infrared spectrophotometer (FT-IR). This analysis confirmed the presence or absence of residual organic matter. The evaluation criteria were as follows: (Good) Almost no residual organic matter is found (800-4000 cm -1 (maximum absorption at 1000kJ / s is less than 0.1) (Fairly good) Residual organic matter is observed (800-4000 cm -1 The maximum absorption at (Poor) Residual organic matter is found (800-4000 cm -1 (maximum absorption at 0.2 or greater)

[0143] The results of the evaluation tests carried out as described above are also shown in Table 1. As can be seen from the above evaluation results, the protective layer of the protective sheet of the example was able to protect the surface to be protected and could be removed relatively easily with water. Furthermore, the protective layer of the protective sheet of the example contains the liquid component described above in addition to the solid hydrophilic polymer described above, and therefore has good adhesion to the protective surface of the object to be protected, and also has good processability (ability to suppress the occurrence of microcracks). [Industrial Applicability]

[0144] The protective sheet of the present invention is suitably used, for example, in the production of semiconductor devices having semiconductor integrated circuits and the like. [Explanation of symbols]

[0145] 1: Protective sheet, 11: protective layer, 11': small piece of protective layer, 15: release liner, 20: dicing tape, 21: Base material layer, 22: Adhesive layer, 30: Die bond sheet, 50: Dicing die bond film, W: semiconductor wafer, X: semiconductor chip, B: backgrinding tape.

Claims

1. a protective layer that is removed by a liquid containing water after protecting at least a part of the surface of the object to be protected; the protective layer contains a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in its molecule, the hydrophilic polymer comprises polyvinyl alcohol, polyvinylpyrrolidone, a water-soluble polyester polymer, polyethylene oxide, polyacrylic acid, or polyvinylacetamide; the liquid compound has a hydrophilic group in its molecule, the hydrophilic group being a hydroxy group, a carboxy group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, or a polyoxyethylene group; The protective sheet, wherein the protective layer has a storage modulus E' at 70°C of 0.01 GPa or more and 0.1 GPa or less.

2. a protective layer that is removed by a liquid containing water after protecting at least a part of the surface of the object to be protected; the protective layer contains a solid hydrophilic polymer and a liquid compound containing a hydrophilic group in its molecule, the hydrophilic polymer comprises polyvinyl alcohol, polyvinylpyrrolidone, a water-soluble polyester polymer, polyethylene oxide, polyacrylic acid, or polyvinylacetamide; the liquid compound has a hydrophilic group in its molecule, the hydrophilic group being a hydroxy group, a carboxy group, a sulfonic acid group, a pyrrolidone group, an amine-containing group, or a polyoxyethylene group; A protective sheet, wherein when the protective layer is subjected to dynamic viscoelasticity measurement, the peak temperature of Tan δ (E" / E'), which is the ratio of loss modulus E" to storage modulus E', is less than 70°C.

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

4. The protective sheet according to claim 1 or 2, wherein the protective layer contains the liquid compound in an amount of 1 part by mass to 60 parts by mass, based on 100 parts by mass of the hydrophilic polymer.

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