Protective sheet

Abstract

Provided is a protective sheet provided with: a protective layer for protecting at least a part of the surface of a substrate, which is an object to be protected; a substrate layer disposed so as to face one surface of the protective layer; an adhesive layer that is disposed between the protective layer and the base material layer, and that is adhered to the protective layer and the base material layer such that both surfaces thereof can be peeled off from each other; and a release liner that overlaps the other surface of the protective layer, the protective layer being configured so as to contain a hydrophilic polymer having a hydrophilic group in the molecule, and at least a part of the protective layer being dissolved and removed from the surface of the substrate when the protective layer is in contact with a liquid containing water.

Description

Technical Field

[0001] This application claims the priority of Japanese Patent Application No. 2022-095956, 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 manufacture of electronic devices such as semiconductor devices, there have been known protective sheets for protecting at least a portion of the surface of an object to be protected. The object to be protected by such protective sheets is, for example, a substrate such as a semiconductor wafer. Such protective sheets are used by being attached to at least a portion of the surface of a substrate in the manufacturing process of a 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 sheet and an adhesive sheet 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 back grinding process, in which the back grinding tape is superimposed on the circuit surface of the circular semiconductor wafer, and in the state where the semiconductor wafer and the back grinding tape are stacked, the surface of the semiconductor wafer without the circuit components is ground until the semiconductor wafer becomes a specified thickness; a fixing process, in which the surface of the semiconductor wafer that has been ground (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 large number of semiconductor chips (dies) are obtained by fragmenting the semiconductor wafer; 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 chip bonding sheet and the dicing tape are peeled off to take out the semiconductor chip with the chip bonding sheet attached; a chip bonding process, in which the semiconductor chip with the chip bonding sheet attached is bonded to the adherend via the chip bonding sheet; and a curing process, in which the chip bonding sheet bonded to the adherend is thermally cured. A semiconductor device is manufactured through, for example, these steps.

[0006] As the protective sheet, for example, there is known a protective sheet that is used as a temporary fixing sheet for temporarily fixing a semiconductor wafer in the back grinding step or dicing step of the post-process and is subsequently removed with water (for example, Patent Document 1).

[0007] The protective sheet described in Patent Document 1 has a resin composition containing an oxyalkylene-containing polyvinyl alcohol-based resin having a saponification degree of 55 mol% or less, and may further have a release material on one or both sides of the resin composition as required. 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.

[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, when the tape having the protective layer formed of the resin composition described in Patent Document 1 and the release material is attached to the substrate and used, for example, instead of the back grinding tape in the back grinding process, the release material and the protective layer may be peeled off due to the force applied during the grinding process. On the other hand, in order to suppress the peeling as described above, for example, it is necessary to grind the protective layer attached to the substrate in a state where the back grinding tape is separately superimposed.

[0013] Thus, although the protective layer formed of the resin composition of the protective sheet described in Patent Document 1 can be removed from the surface of the substrate to be protected by relatively low-temperature water, it is difficult to use it for the purpose of back grinding tape during grinding in the back grinding process.

[0014] On the other hand, it cannot be said that sufficient research has been conducted on a protective sheet that not only includes a protective layer that can be relatively easily removed by contact with a liquid containing water but can also be used for grinding in a back grinding process.

[0015] Therefore, an object of the present invention is to provide a protective sheet having a protective layer that can be relatively easily removed from the surface of a substrate to be protected by contact with a liquid containing water and that can also be used for grinding the substrate in a back grinding step.

[0016] Solutions for solving problems

[0017] In order to solve the above-mentioned problems, the protective sheet of the present invention comprises: a protective layer for protecting at least a portion of the surface of a substrate as a protected object; a base material layer arranged opposite to one side of the protective layer; an adhesive layer arranged between the protective layer and the base material layer and bonded to the protective layer and the base material layer in a manner that each side surface can be peeled off separately; and a peeling liner overlapping the other side of the protective layer, wherein the protective layer has the following structure: it contains a hydrophilic polymer having a hydrophilic group in its molecule, and when it comes into contact with a liquid containing water, at least a portion of the protective layer dissolves and is removed from the surface of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0020] Figure 2A This is a schematic cross-sectional view showing an example of a state where the release liner of the protective sheet of the present embodiment is removed.

[0021] Figure 2B This is a schematic cross-sectional view showing an example of a wetting step in a method for manufacturing an electronic device.

[0022] Figure 2C This is a schematic cross-sectional view showing an example of a protection step in a method for manufacturing an electronic device.

[0023] Figure 2D 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.

[0024] Figure 2E This is a schematic cross-sectional view showing an example of a state where a substrate is ground in a method of manufacturing an electronic device.

[0025] Figure 2F This is a schematic cross-sectional view showing an example of a state after a substrate is ground in a method of manufacturing an electronic device.

[0026] Figure 2G This is a schematic cross-sectional view showing an example of a state where a bonding layer is cured in a method of manufacturing an electronic device.

[0027] Figure 2H This is a schematic cross-sectional view showing an example of a state of a peeling step in a method for manufacturing an electronic device.

[0028] Fig.2I This is a schematic cross-sectional view showing an example of a state after a lift-off step in a method for manufacturing an electronic device.

[0029] Figure 2J This is a schematic cross-sectional view showing an example of a state where a protective layer is subjected to a hydrophilic treatment in a method for manufacturing an electronic device.

[0030] Figure 2K This is a schematic cross-sectional view showing an example of a removing step in the method for manufacturing an electronic device.

[0031] Figure 3A This is a schematic cross-sectional view showing an example of a state after a protection step in a method of manufacturing a semiconductor device.

[0032] Figure 3B This is a schematic cross-sectional view showing an example of a grinding process performed on a semiconductor wafer in a method for manufacturing a semiconductor device.

[0033] Figure 3C This is a schematic cross-sectional view showing an example of a state after a semiconductor wafer is ground in a method of manufacturing a semiconductor device.

[0034] Figure 3D This is a cross-sectional view showing an example of a state after a fixing step in a method of manufacturing a semiconductor device.

[0035] Figure 3E This is a schematic cross-sectional view showing an example of a state where a bonding layer is cured in a method of manufacturing a semiconductor device.

[0036] Figure 3F This is a schematic cross-sectional view showing another example of the curing treatment of the adhesive layer in the method for manufacturing a semiconductor device.

[0037] Figure 3G This is a schematic cross-sectional view showing an example of a lift-off step in a method for manufacturing a semiconductor device.

[0038] Figure 3H This is a schematic cross-sectional view showing an example of a state after a lift-off step in a method of manufacturing a semiconductor device.

[0039] Fig. 3I This is a cross-sectional view showing an example of a situation in the middle of a blade dicing process in a method of manufacturing a semiconductor device.

[0040] Figure 3J This is a schematic cross-sectional view showing an example of a state in which a protective layer is subjected to a hydrophilic treatment in a method for manufacturing a semiconductor device.

[0041] Figure 3K This is a schematic cross-sectional view showing an example of a removal step in a method for manufacturing a semiconductor device.

[0042] Figure 3L This is a schematic cross-sectional view showing an example of a pickup step in a method for manufacturing a semiconductor device.

[0043] Figure 3M This is a schematic cross-sectional view showing an example of a state after a bonding step in a method of manufacturing a semiconductor device.

[0044] Figure 4A This is a schematic cross-sectional view showing a state of a half-cutting process performed on a semiconductor wafer in a method of manufacturing a semiconductor device.

[0045] Figure 4B This is a schematic cross-sectional view showing a state after a half-cutting process is performed on a semiconductor wafer in a method of manufacturing a semiconductor device.

[0046] Figure 4C This is a schematic cross-sectional view showing a state after a protection step in a method of manufacturing a semiconductor device.

[0047] Figure 4D This is a schematic cross-sectional view showing a state after a protection step in a method of manufacturing a semiconductor device.

[0048] Figure 4E This is a schematic cross-sectional view showing another example of the grinding process performed on a semiconductor wafer in the method for manufacturing a semiconductor device.

[0049] Figure 4F This is a schematic cross-sectional view showing another example of a state after a semiconductor wafer is ground in a method of manufacturing a semiconductor device.

[0050] Figure 4G This is a schematic cross-sectional view showing another example of the fixing step in the method for manufacturing a semiconductor device.

[0051] Figure 4H This is a schematic cross-sectional view showing another example of the state after the fixing step in the method for manufacturing a semiconductor device.

[0052] Fig. 4I This is a schematic cross-sectional view showing another example of the state after the lift-off step in the method for manufacturing a semiconductor device.

[0053] Figure 4J This is a schematic cross-sectional view showing an example of a state of an expansion step in a method for manufacturing a semiconductor device.

[0054] Figure 4KThis is a schematic cross-sectional view showing another example of the hydrophilization treatment of the protective layer in the method for manufacturing a semiconductor device.

[0055] Figure 4L This is a schematic cross-sectional view showing another example of the removal step in the method for manufacturing a semiconductor device.

[0056] Figure 5A This is a cross-sectional view of an example of a dicing tape cut in the thickness direction.

[0057] Figure 5B This is a cross-sectional view of an example of a dicing die bonding film cut in the thickness direction. DETAILED DESCRIPTION

[0058] Hereinafter, the 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 the length ratio of the vertical and horizontal lengths is not necessarily the same as that of the actual object. This is true for any of the drawings.

[0059] like Figure 1A As shown, the protective sheet 1 of this embodiment comprises: a protective layer 11 for protecting at least a portion of the surface of a substrate as a protected object; a base material layer 15, arranged opposite to one side of the protective layer 11; an adhesive layer 13, arranged between the protective layer 11 and the base material layer 15, and bonded to the protective layer 11 and the base material layer 15 in a manner that each side thereof can be peeled off separately; and a peeling liner 17, overlapping the other side of the protective layer 11, wherein the protective layer 11 comprises a hydrophilic polymer having a hydrophilic group in the molecule so that at least a portion of it is dissolved and removed from the surface of the substrate when in contact with a liquid containing water.

[0060] In more detail, the protective sheet 1 of the present embodiment comprises: a release liner 17 and a substrate layer 15 facing each other; a protective layer 11, which is in contact with the release liner 17 between the release liner 17 and the substrate layer 15 and is used to protect at least a portion of the surface of a substrate that is a protected object; and an adhesive layer 13, which is in contact with the substrate layer 15 between the release liner 17 and the substrate layer 15 and is bonded to the protective layer 11 in a releasable manner, the peeling force between the substrate layer 15 and the adhesive layer 13 being greater than the peeling force between the release liner 17 and the protective layer 11, and the protective layer 11 comprising a hydrophilic polymer having a hydrophilic group in its molecule so that at least a portion of it dissolves and is removed from the surface of the substrate when in contact with a liquid containing water.

[0061] According to the protective sheet 1 formed by the above-mentioned structure, the release liner 17 overlapping the protective layer 11 can be peeled off, so that the protective layer 11 is superimposed on the protected surface of the substrate. Thus, the protected surface can be covered and protected by the protective layer 11. In addition, a semiconductor wafer or the like can be used as a substrate, and the surface on the opposite side of the surface of the substrate overlapping the protective layer 11 can be cut by back grinding. In detail, a laminate of a base material layer 15, an adhesive layer 13 and a protective layer 11 can be used instead of the so-called back grinding tape to perform back grinding on the surface of the substrate on the opposite side of the surface of the substrate covered by the protective layer 11. In other words, back grinding can be performed even without using a back grinding tape separately. Moreover, even if an external force is applied during the back grinding process, the adhesive layer 13 can maintain a state of adhesion with the base material layer 15 and the protective layer 11 by its adhesive force. In addition, the protective layer 11 can be well bonded to the substrate through the hydrophilic group of the hydrophilic polymer and maintain a state of adhesion with the substrate.

[0062] Afterwards, by bringing a liquid containing water into contact with the protective layer 11, at least a portion of the protective layer 11 can be dissolved. Thus, after protecting the protected surface of a protected object such as a substrate, the protective layer 11 can be removed relatively easily by a liquid containing water. Therefore, in order to remove the protective layer 11 from the protected surface, the protective layer 11 can be removed even without using a peeling tape that is affixed to the protective layer 11. Therefore, the phenomenon of unintentionally leaving a portion of the protective layer 11 on the protected surface (residual adhesive) can be suppressed. In addition, since the hydrophilic polymer in the protective layer 11 has a hydrophilic group, even if charging occurs near the protected surface, the adverse effects of charging can be suppressed.

[0063] As described above, the protective sheet 1 of this embodiment includes the release liner 17, the protective layer 11, the adhesive layer 13, and the base layer 15 in a sequentially laminated state. Each layer is arranged so that the laminate of the protective layer 11 and the adhesive layer 13 is sandwiched between the release liner 17 and the base layer 15.

[0064] In the protective sheet 1 of the present embodiment, the protective layer 11 is arranged at a position closer to the release liner 17 than the adhesive layer 13. The adhesive layer 13 is arranged at a position closer to the base layer 15 than the protective layer 11. The peeling force between the release liner 17 and the protective layer 11 is smaller than the peeling force between the base layer 15 and the adhesive layer 13. In the protective sheet 1 of the present embodiment, when the adhesive layer 13 is peeled off from the surface of the protective layer 11, the peeling force between the base layer 15 and the adhesive layer 13 is stronger, for example, greater than the peeling force between the protective layer 11 and the adhesive layer 13 described above. In addition, for example, before the adhesive layer 13 is subjected to a curing treatment (described later), the adhesive force possessed by the adhesive layer 13 itself may be higher than the adhesive force possessed by the protective layer 11 itself.

[0065] [Base layer of protective sheet]

[0066] The surface of the substrate layer 15 that contacts the adhesive layer 13 may be primer-treated. The substrate layer 15 may be a resin film. Examples of the resin film include polyethylene terephthalate resin films, polyethylene films, and polypropylene films.

[0067] [Release liner of protective sheet]

[0068] The surface of the release liner 17 that contacts the protective layer 11 may be subjected to release treatment. The release liner 17 may be a resin film. Examples of the resin film include polyethylene terephthalate resin films, polyethylene films, and polypropylene films.

[0069] [Protective layer of protective sheet]

[0070] The protective layer 11 includes a hydrophilic polymer having a hydrophilic group in its molecule. When the protective layer 11 is removed, at least a portion of the protective layer 11 is dissolved when it comes into contact with a liquid containing water and is removed from the surface of the substrate.

[0071] The protective layer 11 may further include a compound that generates an acid or a base by at least one of heating or irradiation with active energy rays (hereinafter, also referred to as an ion generating compound). The protective layer 11 includes the ion generating compound, and thus at least one of the heating treatment or the irradiation treatment with active energy rays (hereinafter, also referred to as a hydrophilization treatment) increases the hydrophilicity of the protective layer 11, so that the protective layer 11 is more easily dissolved in a liquid containing water. The ion generating compound will be described in detail later.

[0072] The protective layer 11 is used, for example, to temporarily protect a protected surface of the substrate (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.

[0073] Examples of the substrate include substrates constituting electronic devices such as semiconductor devices, etc. Examples of the substrate include circuit boards such as semiconductor wafers, dummy wafers, etc.

[0074] For example, when the semiconductor wafer is subjected to a back grinding process in order to reduce the thickness of the semiconductor wafer, the protective layer 11 functions like an adhesive portion of a so-called back grinding tape and can be bonded (pressure-sensitively bonded) to the protected surface (circuit surface) of the semiconductor wafer.

[0075] In addition, the protective layer 11 can be cut into small pieces together with the substrate (semiconductor wafer) while being attached to the protected surface (circuit surface) of the substrate (semiconductor wafer). In this case, foreign matter such as debris that may be generated by the small pieces can be prevented from adhering to the protected surface (circuit surface), thereby protecting the protected surface (circuit surface) of the semiconductor wafer.

[0076] The protective layer 11 may have a property that it is easy to be stretched in the plane direction and be fragmented. 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).

[0077] 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 does not need to have the physical property of being easily cut into small pieces as described above.

[0078] 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.

[0079] The above-mentioned protective layer 11 has the adhesion to the protected surface of the substrate. The adhesion of the above-mentioned protective layer 11 to the substrate is represented by the peeling force when the above-mentioned protective layer 11 is peeled off from the silicon bare wafer serving as the substrate, for example. The peeling force of the above-mentioned protective layer 11 at 25°C may be 10.0 [N / 10mm] or less, and may be 8.0 [N / 10mm] or less. The above-mentioned peeling force may be 0.01 [N / 10mm] or more. It should be noted that the numerical value of the above-mentioned peeling force is the value before the protective layer 11 is subjected to at least one of the heating treatment and the irradiation treatment with active energy rays (the above-mentioned hydrophilization treatment).

[0080] The above-mentioned peeling force is measured under the following measurement conditions.

[0081] First, 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 described below. Specifically, 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 10 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.

[0082] In the present embodiment, the hydrophilic group of the hydrophilic polymer contained in the protective layer 11 may be at least one selected from the group consisting of, for example, a hydroxyl group, a carboxyl group, a sulfonic acid group, a pyrrolidone group, and a polyoxyethylene group.

[0083] Since the hydrophilic polymer has the hydrophilic group (especially hydroxyl group) in the molecule, the protective layer 11 can be sufficiently adhered to the protected surface of the substrate.

[0084] 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.

[0085] 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.

[0086] Each of the plurality of side chains in the above-mentioned hydrophilic polymer may contain 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 to the end of the side chain, or may have an atomic sequence of an ester group such as -O-(C=O)-.

[0087] 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 alkylene group, and a hydrophilic group.

[0088] 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.

[0089] 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, or polyethylene oxide (PEO) (e.g., having a molecular weight of 50,000 or more), and the like.

[0090] The hydrophilic polymer may be, for example, water-soluble. Specifically, the hydrophilic polymer may have water solubility such that a thin film (thickness of 50 μm or less) of the hydrophilic polymer is completely dissolved when immersed in water at 40° C. It should be noted that the hydrophilic polymer may not necessarily be water-soluble, but preferably, the protective layer 11 after the hydrophilization treatment (described in detail later) has water solubility such that the thin film is completely dissolved in water at 40° C.

[0091] The hydrophilic polymer is preferably at least one selected from the group consisting of polyvinyl alcohol, a water-soluble polyester polymer, and polyoxyethylene.

[0092] When the hydrophilic polymer is polyvinyl alcohol (PVA), the saponification degree (mol %) of the polyvinyl alcohol may be 20 or more and 100 or less before the protective layer 11 is subjected to a hydrophilization treatment (described in detail later).

[0093] The saponification degree (mol %) of the polyvinyl alcohol is preferably 25 or more, more preferably 35 or more. As the saponification degree of the polyvinyl alcohol increases, the protective layer 11 has higher hydrophilicity after the hydrophilization treatment. Therefore, the protective layer 11 can be removed more easily by a liquid containing water.

[0094] On the other hand, the degree of saponification of the polyvinyl alcohol is preferably 80 or less, more preferably 60 or less, from the viewpoint of further improving the adhesion to the substrate.

[0095] <Saponification degree measurement method and measurement conditions>

[0096] The above saponification degree was determined by proton nuclear magnetic resonance spectroscopy under the following analytical conditions: 1 HMNR) was used for determination.

[0097] 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.

[0098] Analytical apparatus: FT-NMR.

[0099] (For example, "AVANCEIII-400" manufactured by Bruker Biospin.)

[0100] Observation frequency: 400MHz(1H).

[0101] Determination solvent: heavy water or heavy dimethyl sulfoxide (heavy DMSO).

[0102] Measurement temperature: 80℃.

[0103] Chemical shift standard: external standard TSP-d4 (0.00 ppm) (when measuring with heavy water).

[0104] : Measurement solvent (2.50 ppm) (in case of heavy DMSO measurement).

[0105] <Calculation of Saponification Degree>

[0106] The saponification degree was calculated according to 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). It should be noted that in the following formula, VOH (-CH2-) is the intensity of the peak derived from the methylene group of the vinyl alcohol unit (VOH), and VAc (CH3CO-) is the intensity of the peak derived from the acetyl group of the vinyl acetate unit (VAc).

[0107]

[0108] The average degree of polymerization of the polyvinyl alcohol is preferably 100 or more, and more preferably 200 or more. Furthermore, the average degree of polymerization is preferably 1000 or less, and more preferably 800 or less.

[0109] When the average degree of polymerization of polyvinyl alcohol is 100 or more, the protective layer 11 is more easily formed. On the other hand, when the average degree of polymerization of polyvinyl alcohol is 1000 or less, the hydrophilicity of polyvinyl alcohol is further increased, and the protective layer 11 is more easily dissolved in a liquid containing water.

[0110] The above-mentioned average degree of polymerization is determined by the following measurement method and measurement conditions.

[0111] <Method and conditions for measuring average degree of polymerization>

[0112] ·Analysis device: Gel permeation chromatography analysis device.

[0113] (For example, the device is manufactured by Agilent and is called "1260 Infinity".)

[0114] Chromatographic columns: TSKgel G6000PWXL and TSKgel G3000PWXL (manufactured by Tosoh Corporation, connected in series).

[0115] Column temperature: 40°C.

[0116] Eluent: 0.2 M sodium nitrate aqueous solution.

[0117] Flow rate: 0.8 mL / min.

[0118] Injection volume: 100 μL.

[0119] · Detector: Differential Refractometer (RI).

[0120] Standard samples: PEG standard samples and PVA standard samples.

[0121] 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).

[0122] The water-soluble polyester polymer (PES) is, for example, an esterification product of at least a polycarboxylic acid and a polyol. The water-soluble polyester polymer also has at least one of an anionic hydrophilic group, a cationic hydrophilic group, or a nonionic hydrophilic group in the molecule. As the anionic hydrophilic group, for example, a sulfonic acid group (including a salt state), a carboxyl group (including a salt state), etc. can be listed. As the cationic group, for example, an amine-containing group can be listed. As the nonionic group, for example, a polyoxyethylene group can be listed.

[0123] 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.) at low temperatures can be improved. In addition, the protective layer 11 can be more easily removed from the surface of the substrate by a liquid containing water.

[0124] The mass average molecular weight Mw of the above-mentioned polyoxyethylene (PEO) is preferably below 1000000 (1 million). By the mass average molecular weight Mw being below 1000000, 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.) at low temperatures can become better. In addition, the protective layer 11 can be efficiently removed from the surface of the substrate in a shorter time by a liquid comprising water.

[0125] As described above, the protective layer 11 may further contain the above-mentioned ion-generating compound that generates an acid or a base by at least one of heating and irradiation with active energy rays (hydrophilization treatment).

[0126] By subjecting the protective layer 11 to the above-mentioned hydrophilic treatment, an acid or a base is generated from the above-mentioned ion-generating compound. Thus, the hydrophilicity of the protective layer 11 is improved. At least a portion of the protective layer 11 with improved hydrophilicity can be more easily dissolved in the liquid by contacting with the liquid containing water. Therefore, the whole or a portion of the protective layer 11 with improved hydrophilicity becomes more easily dissolved in the liquid containing water, and the protective layer 11 is more easily detached from the protected surface.

[0127] Thus, the protective layer 11 containing the above-mentioned ion-generating compound can not only protect the protected surface of the substrate, but also has the physical property of improving the hydrophilicity through the above-mentioned hydrophilization treatment, so after protecting the protected surface, it can be more easily removed from the protected surface by a liquid containing water.

[0128] In addition, the hydrophilization treatment such as the heat treatment or the irradiation treatment with active energy rays will be described in detail later.

[0129] In this embodiment, the ion generating compound is, for example, an acid generator that generates an acid by at least one of heating or irradiation with active energy rays, or a base generator that generates a base by at least one of heating or irradiation with active energy rays. Examples of the ion generating compound include photoacid generators, photobase generators, thermal acid generators, and thermal base generators.

[0130] The above-mentioned protective layer 11 only needs to have a hydrophilicity greater than or equal to a prescribed value when it is removed by a liquid containing water. For example, the protective layer 11 containing the above-mentioned ion-generating compound only needs to have a hydrophilicity greater than or equal to a prescribed value after the hydrophilization treatment as described above. Therefore, before the above-mentioned hydrophilization treatment, the above-mentioned protective layer 11 may have a hydrophilicity less than or equal to a prescribed value, or may have a hydrophilicity greater than or equal to a prescribed value. When the above-mentioned protective layer 11 has a hydrophilicity greater than or equal to a prescribed value, usually, at least a portion of the above-mentioned protective layer 11 is dissolved in a liquid containing water.

[0131] 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 above-mentioned water absorption rate can be increased by, for example, increasing the content ratio of the hydrophilic group in the hydrophilic polymer or by increasing the content of the ion generating compound in the protective layer 11. The water absorption rate of the protective layer 11 can be, for example, 10.0% by mass or less.

[0132] It should be noted that, in the case where the protective layer 11 contains the above-mentioned ion-generating compound, the water absorption rate of the protective layer 11 before the above-mentioned hydrophilization treatment can be less than 2.0 mass%. Thus, before the removal step (described in detail later) of removing the protective layer 11, even if the protective layer 11 comes into contact with water, it is possible to suppress the unintentional removal of the protective layer 11. Therefore, before the above-mentioned hydrophilization treatment is performed on the protective layer 11, the protective layer 11 can be sufficiently closely attached to the protected surface, and after the above-mentioned hydrophilization treatment, as described above, the protective layer 11 can be removed from the protected surface more easily.

[0133] On the other hand, the water absorption rate of the protective layer 11 before the hydrophilization treatment can be 0.1 mass % or more. Thus, the protective layer 11 after the hydrophilization treatment can have higher hydrophilicity.

[0134] The water absorption of the protective layer 11 is determined based on the measured value of the coulometric titration method using the Karl Fischer method. If necessary, the water absorption is also measured using the protective layer 11 after the hydrophilic treatment. Specifically, a test sample that has reached a steady state under an environment of a temperature of 23°C and a humidity of 50RH% is heated at 150°C for 3 minutes by a water vaporization device, and the vaporized water is measured. The water absorption is determined based on the ratio of the measured water content to the mass of the heated test sample.

[0135] The above-mentioned ion generating compound is preferably an acid generator such as a photoacid generator or a thermal acid generator, or a base generator such as a photobase generator or a thermal base generator. It should be noted that sometimes a compound has the functions of both a photoacid generator and a thermal acid generator. In other words, for example, sometimes a specific acid generator generates an acid by either a heat treatment or an irradiation treatment with active energy rays. The same is true for the base generator.

[0136] When the ion generating compound is a photoacid generator, a photobase generator, a thermal acid generator, or a thermal base generator, an acid or a base is more fully generated in the protective layer 11 by heat treatment or irradiation with active energy rays such as ultraviolet irradiation. Therefore, the hydrophilicity of the protective layer 11 is further improved. Therefore, the protective layer 11 can be more easily removed from the protected surface by a liquid containing water.

[0137] The photoacid generator as the acid generator is, for example, a photocationic polymerization initiator generally used for cationic polymerization. The thermal acid generator as the acid generator is, for example, a thermal cationic polymerization initiator generally used for cationic polymerization.

[0138] The photobase generator as the base generator is, for example, a photoanionic polymerization initiator generally used for anionic polymerization. The thermal base generator as the base generator is, for example, a thermal anionic polymerization initiator generally used for anionic polymerization.

[0139] As the above-mentioned photoacid generator, thermal acid generator, photobase generator, or thermal base generator, commercially available products can be used.

[0140] Examples of the photoacid generator include onium salt compounds, sulfonyl imide compounds, and disulfonyldiazomethane compounds.

[0141] Examples of the onium salt compound generally used include onium salt compounds such as iodonium salt compounds, sulfonium salt compounds, oxime sulfonate compounds, and diazonium salt compounds.

[0142] Examples of the iodonium salt compound include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, bis(4-tert-butylphenyl)iodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, benzyl-4-hydroxyphenylmethylsulfonium hexafluorophosphate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, bis(4-fluorophenyl)iodonium trifluoromethanesulfonate, and diphenyliodonium hexafluorophosphate.

[0143] Examples of the sulfonium salt compound include diphenyl[4-(phenylsulfonyl)phenyl]sulfonium=trifluorotris(pentafluoroethyl)-λ 5 -phosphide, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoro-n-butylsulfonate, triphenylsulfonium camphorsulfonate, 4,7-di-n-butoxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium adamantanecarboxylic acid trifluoroethanesulfonate, triphenylsulfonium p-toluenesulfonate, triphenylsulfonium methanesulfonate, triphenylsulfonium phenolsulfonate, triphenylsulfonium nitrate, triphenylsulfonium maleate, bis(triphenylsulfonium) maleate, triphenylsulfonium hydrochloride, triphenylsulfonium acetate, triphenylsulfonium trifluoroacetate, triphenylsulfonium salicylate, triphenylsulfonium benzoate, or triphenylsulfonium hydroxide.

[0144] Examples of the oxime sulfonate compound include (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (5-octylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (camphorsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (5-p-toluenesulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, and (5-octylsulfonyloxyimino)-(4-methoxyphenyl)acetonitrile.

[0145] Examples of the diazonium salt compound include 4-nitrobenzenediazonium tetrafluoroborate and the like.

[0146] Examples of commercially available products of onium salt compounds include optomer SP-150, optomer SP-170, optomer SP-171 (all manufactured by ADEKA), UVE-1014 (manufactured by General Electric), OMNICAT 250, OMNICAT 270 (all manufactured by IGM Resin), IRGACURE 290 (manufactured by BASF), San-Aid SI-60L, San-Aid SI-80L, San-Aid SI-100L (all manufactured by Sanshin Chemical Industries, Ltd.), or CPI-100P, CPI-101A, CPI-200K (all manufactured by San-Apro), etc.

[0147] Examples of the sulfonyl imide compound as the photoacid generator include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoro-n-butylsulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, N-(trifluoromethanesulfonyloxy)naphthalimide, N-(camphorsulfonyloxy)succinimide, N-(4-methylphenylsulfonyloxy)succinimide, N-(2-trifluoromethylphenylsulfonyloxy)succinimide, N-(4-fluorophenylsulfonyloxy)succinimide, N-(trifluoromethyl ... N-(trifluoromethylsulfonyloxy)phthalimide, N-(camphorsulfonyloxy)phthalimide, N-(2-trifluoromethylphenylsulfonyloxy)phthalimide, N-(2-fluorophenylsulfonyloxy)phthalimide, N-(trifluoromethylsulfonyloxy)diphenylmaleimide, N-(camphorsulfonyloxy)diphenylmaleimide, or 4-methylphenylsulfonyloxy)diphenylmaleimide.

[0148] Examples of the disulfonyldiazomethane compound as the photoacid generator include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(benzenesulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-ditoluenesulfonyl)diazomethane, and methanesulfonyl-p-toluenesulfonyldiazomethane.

[0149] Examples of the photoacid generator include 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-triazine.

[0150] Examples of the thermal acid generator include aryl diazonium salts, diaryliodonium salts, triarylsulfonium salts, triarylsulfoxonium salts, pyridinium salts, quinolinium salts, isoquinolinium salts, sulfonic acid esters, and iron arene complexes.

[0151] Examples of the photobase generator include radiation-sensitive base generators containing a heterocyclic group such as 4-(methylthiobenzoyl)-1-methyl-1-morpholinoethane, (4-morpholinobenzoyl)-1-benzyl-1-dimethylaminopropane, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone, N-(2-nitrobenzyloxycarbonyl)pyrrolidine, and 1-(anthraquinone-2-yl)ethylimidazolecarboxylate. Other examples include 2-nitrobenzylcyclohexylcarbamate, [[(2,6-dinitrobenzyl)oxy]carbonyl]cyclohexylamine, bis[[(2-nitrobenzyl)oxy]carbonyl]hexane-1,6-diamine, triphenylmethanol, o-carbamoylhydroxylamine, o-carbamoyl oxime, hexaaminecobalt(III)tris(triphenylmethylborate), 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanide-n-butyltriphenylborate, acetophenone o-benzoyl oxime, and 2-(9-oxoxanthene-2-yl)propanoic acid 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0152] Examples of the thermal base generator include carbamate derivatives such as 1-methyl-1-(4-biphenylyl)ethylcarbamate, 1,1-dimethyl-2-cyanoethylcarbamate, or benzoylcyclohexylcarbamate, urea derivatives such as urea or N,N-dimethyl-N'-methylurea, dihydropyridine derivatives such as 1,4-dihydronicotinamide, and quaternary ammonium salts of organosilanes or organoboranes.

[0153] In the protective layer 11, the amount of the ion generating compound is preferably 1 part by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the hydrophilic polymer. Thus, the protective layer 11 can have higher hydrophilicity after the hydrophilization treatment.

[0154] It should be noted that the amount of the ion generating compound may be 10 parts by mass or less, or 8 parts by mass or less, relative to 100 parts by mass of the hydrophilic polymer.

[0155] The protective layer 11 of the present embodiment may contain, in addition to the above-mentioned compounding components, for example, a solvent, a surfactant, etc. Examples of the solvent include water and an organic solvent.

[0156] The organic solvent is preferably a relatively volatile organic solvent, and examples of such an organic solvent include ethanol and methanol.

[0157] [Adhesive layer of protective sheet]

[0158] The adhesive layer 13 may have a thickness of 5 μm or more and 40 μm or less. The shape and size of the adhesive layer 13 are generally the same as those of the protective layer 11 .

[0159] The adhesive layer 13 has a large adhesive force. The adhesive force of the adhesive layer 13 is, for example, greater than the adhesive force of the protective layer 11. The adhesive force of the adhesive layer 13 is measured by the same method as the method for measuring the peeling force when the protective layer 11 is peeled off from the silicon bare wafer.

[0160] In the present embodiment, the peeling force between the base layer 15 and the adhesive layer 13 is preferably greater than the peeling force between the adhesive layer 13 and the protective layer 11 and the peeling force between the protective layer 11 and the release liner 17 .

[0161] In the present embodiment, the adhesive layer 13 includes, for example, a polymer compound. The polymer compound that may be included in the adhesive layer 13 may be a cross-linking polymer compound that can undergo a cross-linking reaction by a curing treatment. In the case where the adhesive layer 13 includes a cross-linking polymer compound, the adhesive layer 13 is cured by subjecting the adhesive layer 13 to a curing treatment. The adhesive force of the adhesive layer 13 is reduced by curing the adhesive layer 13. Therefore, it is easier to peel off between the adhesive layer 13 and the protective layer 11. The details of the curing treatment will be described later.

[0162] On the other hand, the adhesive layer 13 may be designed to be non-curable. For example, the adhesive layer 13 may be made such that no further curing reaction occurs by fully subjecting the adhesive layer 13 containing the cross-linkable polymer compound to a curing treatment (no curing occurs by the curing treatment). In addition, for example, the adhesive layer 13 may be made of a non-cross-linkable acrylic copolymer having a (meth) alkyl ester unit described later as a monomer unit in the molecule, thereby making the adhesive layer 13 non-curable.

[0163] The polymer compound that can be included in the adhesive layer 13 may be, for example, an acrylic copolymer having at least a (meth)acrylic acid alkyl ester unit as a monomer unit in the molecule. The acrylic copolymer may be a cross-linked acrylic copolymer or a non-cross-linked acrylic copolymer.

[0164] In addition, in this specification, the expression "(meth)acrylate" includes both methacrylate (methacrylic acid ester) and acrylate (acrylic acid ester). Similarly, the expression "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0165] Regarding the above-mentioned acrylic copolymer, in the case of either the cross-linked acrylic copolymer or the non-cross-linked acrylic copolymer, it is preferred that at least a (meth) alkyl acrylate unit is contained in the molecule as a monomer unit. The monomer unit is a unit constituting the main chain of the acrylic copolymer. In other words, the monomer unit is derived from a monomer used to polymerize the acrylic copolymer. Each side chain in the above-mentioned acrylic copolymer is contained in each monomer unit constituting the main chain.

[0166] The above-mentioned alkyl (meth)acrylate units are derived from alkyl (meth)acrylate monomers. In other words, the molecular structure after the alkyl (meth)acrylate monomers are polymerized is an alkyl (meth)acrylate unit. The expression "alkyl" means a hydrocarbon part that forms an ester bond with (meth)acrylic acid.

[0167] The alkyl portion (hydrocarbon) in the (meth)acrylic acid alkyl ester unit may be a saturated hydrocarbon or an unsaturated hydrocarbon.

[0168] The alkyl portion (hydrocarbon) in the (meth)acrylic acid alkyl ester unit may be a linear hydrocarbon or a branched hydrocarbon, or may contain a cyclic structure.

[0169] The number of carbon atoms of the alkyl portion (hydrocarbon) in the (meth)acrylate unit may be 2 or more and 22 or less.

[0170] The acrylic copolymer preferably contains, as the alkyl (meth)acrylate unit, an alkyl (meth)acrylate unit having an alkyl moiety with carbon atoms of 6 to 22 (e.g., 6 to 12). It is more preferred that the acrylic copolymer contains a saturated alkyl (meth)acrylate unit having an alkyl moiety with a carbon number of 6 to 22.

[0171] In the acrylic copolymer, the proportion (molar conversion) of the alkyl (meth)acrylate units in all monomer units in the molecule is preferably the highest. For example, the alkyl (meth)acrylate units in all monomer units may account for 50% to 90% in molar conversion.

[0172] The saturated alkyl (meth)acrylate unit preferably does not contain a benzene ring, an ether bond (-CH2-O-CH2-), an -OH group, a -COOH group or any other polar group in the molecule. In the saturated alkyl (meth)acrylate unit, the alkyl portion may be a saturated straight-chain hydrocarbon or a saturated branched-chain hydrocarbon that does not contain atoms other than C and H and consists of 6 or more and 10 or less carbon atoms.

[0173] The acrylic copolymer preferably includes, as the alkyl (meth)acrylate unit, a saturated branched alkyl (meth)acrylate unit having an alkyl moiety with 6 to 10 carbon atoms.

[0174] The structure of the alkyl portion (hydrocarbon portion) of the saturated branched alkyl (meth)acrylate unit may be a saturated branched alkyl structure, and may be an iso structure, a sec structure, a neo structure, or a tert structure.

[0175] Specifically, examples of the saturated branched alkyl (meth)acrylate unit include isoheptyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isostearyl (meth)acrylate units. Among them, the 2-ethylhexyl (meth)acrylate unit is preferred.

[0176] The acrylic copolymer may contain one kind alone or two or more kinds as the alkyl (meth)acrylate unit.

[0177] When the acrylic copolymer is a crosslinkable acrylic copolymer, the crosslinkable acrylic copolymer has, for example, at least a (meth)acrylic acid alkyl ester unit and a crosslinkable group-containing (meth)acrylic acid ester unit as monomer units in the molecule.

[0178] Furthermore, the adhesive layer 13 may contain, for example, the above-mentioned cross-linkable acrylic copolymer, an isocyanate compound, and a polymerization initiator so that the adhesive layer 13 is cured by a curing treatment.

[0179] The (meth)acrylate unit containing a crosslinkable group may have, for example, a hydroxyl group that can form a urethane bond by a urethanization reaction, or a polymerizable group that can be polymerized by a free radical reaction. More specifically, the (meth)acrylate unit containing a crosslinkable group may have either an unreacted hydroxyl group or a free radical polymerizable carbon-carbon double bond as a polymerizable group. In other words, a part of the (meth)acrylate unit containing a crosslinkable group may have an unreacted hydroxyl group, and another part (all other than the above) may not have a hydroxyl group but have a free radical polymerizable carbon-carbon double bond.

[0180] The crosslinkable acrylic copolymer contains, for example, 15 mol parts or more and 60 mol parts or less of crosslinkable group-containing (meth)acrylate units relative to 100 mol parts of alkyl (meth)acrylate units, and 50 mol% or more and 95 mol% or less of the crosslinkable group-containing (meth)acrylate units may contain free radical polymerizable carbon-carbon double bonds.

[0181] The crosslinkable acrylic copolymer may include, for example, a hydroxyl-containing (meth)acrylate unit in which a hydroxyl group is bonded to an alkyl group having a carbon number of 4 or less as a crosslinkable group-containing (meth)acrylate unit. When the adhesive layer 13 includes an isocyanate compound, the isocyanate group of the isocyanate compound can easily react with the hydroxyl group of the hydroxyl-containing (meth)acrylate unit.

[0182] By allowing the crosslinkable acrylic copolymer having a hydroxyl-containing (meth)acrylate unit to coexist with the isocyanate compound in the adhesive layer 13 in advance, the adhesive layer 13 can be appropriately cured. Therefore, the acrylic copolymer can be gelled. Therefore, the adhesive layer 13 can maintain its shape and exhibit adhesive properties.

[0183] The hydroxyl-containing (meth)acrylate unit is preferably a hydroxyl-containing (meth)acrylate C2-C4 alkyl ester unit in which an OH group is bonded to an alkyl part having a carbon number of 2 or more and 4 or less. The expression "C2-C4 alkyl" indicates the number of carbon atoms of the hydrocarbon part that forms an ester bond with (meth)acrylic acid. In other words, the hydroxyl-containing (meth)acrylate C2-C4 alkyl ester monomer refers to a monomer in which (meth)acrylic acid forms an ester bond with an alcohol having a carbon number of 2 or more and 4 or less (usually a diol). The same applies to the following in this specification.

[0184] The hydrocarbon part of the C2-C4 alkyl group is usually a saturated hydrocarbon. For example, the hydrocarbon part of the C2-C4 alkyl group is a straight-chain saturated hydrocarbon or a branched saturated hydrocarbon. The hydrocarbon part of the C2-C4 alkyl group preferably does not contain a polar group containing oxygen (O), nitrogen (N), etc.

[0185] Examples of the hydroxyl-containing (meth)acrylic acid C2-C4 alkyl ester units include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyn-butyl (meth)acrylate, and hydroxyisobutyl (meth)acrylate units. It should be noted that the hydroxyl group (-OH group) may be bonded to the carbon (C) at the terminal of the hydrocarbon portion or to a carbon (C) other than the terminal of the hydrocarbon portion.

[0186] As described above, the crosslinkable acrylic copolymer may include, for example, a polymerizable (meth)acrylate unit having a radically polymerizable carbon-carbon double bond (polymerizable unsaturated double bond) in a side chain as a crosslinkable group-containing (meth)acrylate unit.

[0187] Specifically, the polymerizable (meth)acrylate unit has a molecular structure in which an isocyanate group of an isocyanate group-containing (meth)acrylic monomer and a hydroxyl group of the hydroxyl group-containing (meth)acrylate unit form a urethane bond.

[0188] The cross-linkable acrylic copolymer described above can cure the adhesive layer 13 by irradiation with active energy rays (ultraviolet rays, etc.) through the free radical polymerizable carbon-carbon double bonds of the (meth) acrylate unit containing a cross-linkable group. For example, by irradiation with active energy rays such as ultraviolet rays (curing treatment), free radicals are generated from the photopolymerization initiator, and the cross-linkable acrylic copolymers can be cross-linked by the action of the free radicals. As a result, the adhesive force of the adhesive layer 13 can be reduced. Therefore, the protective layer 11 and the adhesive layer 13 can be more easily peeled off.

[0189] In addition, as a hardening process, the irradiation of the above-mentioned active energy ray can be adopted. As an active energy ray, ultraviolet rays, radiation, and electron beams are adopted.

[0190] The polymerizable (meth)acrylate unit can be prepared by a urethanization reaction after the polymerization reaction of the acrylic copolymer. For example, after copolymerizing an alkyl (meth)acrylate monomer and a hydroxyl-containing (meth)acrylic acid monomer, a part of the hydroxyl groups of the hydroxyl-containing (meth)acrylate unit is subjected to a urethanization reaction with an isocyanate group of an isocyanate-containing polymerizable monomer to obtain a polymerizable (meth)acrylate unit.

[0191] The isocyanate group-containing (meth)acrylic monomer preferably has one isocyanate group and one (meth)acryloyl group in the molecule. Examples of the monomer include 2-methacryloyloxyethyl isocyanate.

[0192] In the present embodiment, the acrylic copolymer may include monomer units other than the above-mentioned monomer units, for example, units such as (meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, or acrylonitrile.

[0193] In the acrylic copolymer contained in the adhesive layer 13, the above-mentioned units (constituent units) can be 1 H-NMR, 13 The molar ratio of the above units in the acrylic copolymer is usually calculated based on the amount (charge amount) of the acrylic copolymer when it is polymerized.

[0194] In this embodiment, the isocyanate compound that the adhesive layer 13 may further include has a plurality of isocyanate groups in the molecule. The isocyanate compound having a plurality of isocyanate groups in the molecule enables a cross-linking reaction between the cross-linking acrylic copolymers in the adhesive layer 13 to proceed. Specifically, the isocyanate group on one side of the isocyanate compound is reacted with the hydroxyl group of the cross-linking acrylic copolymer, and the isocyanate group on the other side is reacted with the hydroxyl group of the other cross-linking acrylic copolymer, thereby enabling a cross-linking reaction through the isocyanate compound to proceed.

[0195] It should be noted that the isocyanate compound may be a compound synthesized through a urethanization reaction or the like.

[0196] Examples of the isocyanate compound include diisocyanates such as aliphatic diisocyanates, alicyclic diisocyanates, and aromatic aliphatic diisocyanates.

[0197] Furthermore, examples of the isocyanate compound include polymeric polyisocyanates such as dimers and trimers of diisocyanates, and polymethylene polyphenylene polyisocyanates.

[0198] In addition, examples of isocyanate compounds include polyisocyanates obtained by reacting an excess of the above-mentioned isocyanate compounds with an active hydrogen-containing compound. Examples of active hydrogen-containing compounds include low molecular weight compounds containing active hydrogen, high molecular weight compounds containing active hydrogen, and the like.

[0199] In addition, as an isocyanate compound, an allophanate polyisocyanate, a biuret polyisocyanate, etc. can also be used.

[0200] The above-mentioned isocyanate compounds can be used alone or in combination of two or more.

[0201] In this embodiment, the polymerization initiator that can be included in the adhesive layer 13 is a compound that can initiate a polymerization reaction by applying heat or light energy. When the adhesive layer 13 includes a polymerization initiator, when heat energy or light energy is provided to the adhesive layer 13, a cross-linking reaction between cross-linked acrylic copolymers can be carried out. Specifically, a polymerization reaction between polymerizable groups can be initiated between cross-linked acrylic copolymers having polymerizable (meth) acrylate units containing free radical polymerizable carbon-carbon double bonds, so that the adhesive layer 13 is cured. As a result, the adhesive force of the adhesive layer 13 is reduced, and the cured adhesive layer 13 can be easily peeled off from the protective layer 11.

[0202] As the polymerization initiator, for example, a photopolymerization initiator or a thermal polymerization initiator is used. As the polymerization initiator, a general commercially available product can be used.

[0203] The adhesive layer 13 may also contain other components other than the above-mentioned components. As other components, for example, adhesion imparting agents, plasticizers, fillers, anti-aging agents, antioxidants, ultraviolet absorbers, light stabilizers, heat stabilizers, antistatic agents, surfactants, or light peeling agents can be listed. The types and usage amounts of other components can be appropriately selected according to the purpose.

[0204] In the protective sheet 1 of this embodiment, for example Figure 1B As shown, the adhesive layer 13 may have a multi-layer structure. For example, the protective sheet 1 may have a first adhesive layer 13A closer to the base layer 15 and a second adhesive layer 13B closer to the protective layer 11 as adhesive layers.

[0205] In the adhesive layer of such a multilayer structure, the second adhesive layer 13B has a lower transmittance of active energy rays than the first adhesive layer 13A. The second adhesive layer 13B may include, for example, a scattering agent for scattering active energy rays, or an absorbent for absorbing active energy rays. When ultraviolet rays are used as active energy rays, the second adhesive layer 13B may include an ultraviolet scattering agent or an ultraviolet absorbent.

[0206] By using the protective sheet 1 having such a multi-layered adhesive layer, when the active energy ray is irradiated toward the adhesive layer from the substrate layer 15 side, the active energy ray is mainly suppressed from reaching the protective layer 11 through the second adhesive layer 13B. Therefore, the adhesive layer is cured by the active energy ray, and on the other hand, the hydrophilization treatment of the protective layer 11 is suppressed. Therefore, in the case where the protective layer 11 contains an ion generating compound and the adhesive layer contains the above-mentioned cross-linked acrylic copolymer or the like, the hydrophilization of the protective layer 11 can be suppressed and the curing of the adhesive layer can proceed.

[0207] In addition, the usage example of the protective sheet 1 which has the first adhesive layer 13A and the second adhesive layer 13B will be described in detail later.

[0208] The above-mentioned protection sheet 1 can be produced by a common method.

[0209] For example, the protective layer 11 can be produced by mixing the hydrophilic polymer, the photoacid generator or plasma generating compound added as needed, and a solvent by a common method, applying the mixture to the release liner 17 , and then volatilizing the solvent from the mixture.

[0210] On the other hand, the adhesive layer 13 can be prepared, for example, by mixing the above-mentioned acrylic copolymer, a polymerization initiator, and a solvent by a common method, applying the mixture to the base layer 15, and then volatilizing the solvent from the mixture. It should be noted that the above-mentioned acrylic copolymer can be polymerized, for example, by a common free radical polymerization reaction.

[0211] When the protective sheet 1 is used, for example, the release liner 17 is peeled off from the protective layer 11, and the protective layer 11 is attached to at least one surface of the substrate (the protected surface of the protected object). Thereafter, for example, the protective layer 11 and the adhesive layer 13 are peeled off to remove the adhesive layer 13 and the base layer 15. Furthermore, at least a portion of the protective layer 11 overlapping the substrate (the protected object) is dissolved by the liquid containing water, and the protective layer 11 is removed from the protected surface.

[0212] As specific examples of the protective sheet 1 described above, for example, the following first to fourth examples can be cited.

[0213] [Protective sheet of the first example]

[0214] The protective layer 11 does not contain the above-mentioned ion generating compound, and the components contained in the adhesive layer 13 do not undergo a cross-linking reaction by the curing treatment. The adhesive layer 13 contains, for example, the above-mentioned non-cross-linking polymer compound.

[0215] [Second Example of Protective Sheet]

[0216] The protective layer 11 contains the above-mentioned ion generating compound, and the components contained in the adhesive layer 13 do not undergo a cross-linking reaction by the curing treatment. The adhesive layer 13 contains, for example, the above-mentioned non-cross-linking polymer compound.

[0217] [Protective sheet of the third example]

[0218] The protective layer 11 does not contain the above-mentioned ion-generating compound, and the adhesive layer 13 contains the above-mentioned cross-linking polymer compound and contains components that undergo a cross-linking reaction by the curing treatment.

[0219] [Protective sheet of the fourth example]

[0220] The protective layer 11 includes the above-mentioned ion-generating compound, and the adhesive layer 13 includes the above-mentioned cross-linkable polymer compound and contains components that undergo a cross-linking reaction by the curing treatment.

[0221] 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 substrate to be protected is a substrate constituting the electronic device.

[0222] The electronic device manufactured by the method for manufacturing an electronic device may be, for example, a semiconductor device such as a semiconductor integrated circuit having a semiconductor chip, or a device having a system LSI having a complementary metal oxide semiconductor (CMOS). Alternatively, the manufactured electronic device may be a device having a mechanical component part, sensor, actuator, or electronic circuit integrated on a silicon substrate, a glass substrate, or an organic material substrate by micromachining technology (MEMS, Micro Electro Mechanical Systems). The manufactured electronic device may be a device having a wiring substrate.

[0223] For example, Figure 2B and Figure 2C As shown, in the manufacturing method of the electronic device, one surface of the substrate S is protected by the 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.

[0224] 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.

[0225] A specific example of a method for manufacturing an electronic device includes: a process for protecting a protected surface by overlapping a stack of the protective layer 11, the adhesive layer 13, and the base layer 15 in the above-mentioned protective sheet 1 on a protected surface of a substrate (so that the protective layer 11 is directly in contact and overlapped); a process for grinding the other surface of the substrate on the opposite side of one surface of the substrate overlapped with the stack to thin the substrate (back grinding process); a process for peeling off the adhesive layer 13 and the protective layer 11 to remove the adhesive layer 13 and the base layer 15 (peeling process); and a process for removing the protective layer 11 by bringing the protective layer 11 overlapping the protected surface into contact with a liquid containing water (removal process), wherein the protective layer 11 contains a hydrophilic polymer having a hydrophilic group in the molecule so that at least a portion of it is dissolved when in contact with the liquid containing water and is removed from the surface of the substrate.

[0226] In the method for manufacturing an electronic device according to the above example, for example, the protective sheet 1 according to any one of the first to fourth examples is used.

[0227] In the manufacturing method of the electronic device of the above example, first, the release liner 17 of the protective sheet 1 is removed, as shown in FIG. Figure 2A As shown in FIG. 1 , a laminate in which the protective layer 11 , the adhesive layer 13 , and the above-mentioned base material layer 15 are laminated in this order is prepared.

[0228] On the other hand, the substrate S is prepared, and if necessary, 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 (see Figure 2B ) By performing the wetting step, the adhesion of the protective layer 11 to the protected surface Sa can be improved.

[0229] 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.

[0230] In the above protection process, for example Figure 2C and Figure 2D As shown, the protective layer 11 of the protective sheet 1 is superimposed on the protected surface Sa of the substrate S. In other words, the protective sheet 1 is superimposed in such a manner that the protective layer 11 is in contact with the protected surface Sa of the substrate S.

[0231] In the above-mentioned protection step, 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 arranged as a circuit component. In the above-mentioned protection step, it is preferable to overlap the protection layer 11 on 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. Examples of the circuit component include circuit wiring, an electrode part, a transistor, a diode, or a sensor part (a light receiving sensor or a vibration sensor, etc.).

[0232] In the back grinding process, in a state where the substrate S, the protective layer 11, the adhesive layer 13, and the base material layer 15 are stacked, a grinding process is performed on the surface of the substrate S where no circuit components are arranged. Figure 2E As shown, grinding (back grinding) using a grinding pad K is performed until the substrate S reaches a predetermined thickness. By grinding, the thickness of the substrate S is reduced to a predetermined thickness (see Figure 2F ).

[0233] In the manufacturing method of the electronic device of the above example, a back grinding step may be performed between the back grinding step and the subsequent peeling step as required, such as Figure 2G As shown, a curing treatment step of irradiating active energy rays is performed on the adhesive layer 13. When the protective sheet of the third example or the fourth example described above is used, a curing treatment step can be performed.

[0234] In the stripping process, Figure 2H As shown, by peeling between the protective layer 11 and the adhesive layer 13, the adhesive layer 13 and the base material layer 15 are removed.

[0235] According to the need, in the manufacturing method of the electronic device device of the above example, the following steps may also be implemented: Fig.2I 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).

[0236] According to the need, in the removal step of the manufacturing method of the electronic device device in the above example, a hydrophilic treatment may also be performed: Figure 2J As shown, the protective layer 11 is subjected to a heating treatment or an irradiation treatment with active energy rays such as ultraviolet rays, thereby generating an acid or a base from the ion generating compound contained in the protective layer 11 to improve the hydrophilicity of the protective layer 11. When the protective sheet of the second example or the fourth example is used, a hydrophilic treatment may be performed.

[0237] Then, in the removal process, Figure 2K As 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.

[0238] 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.

[0239] 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 5A ) to manufacture semiconductor devices. The dicing tape 20 has a base sheet 21 and an adhesive sheet 22. These sheets and the tape are used as auxiliary tools for manufacturing semiconductor devices. It should be noted that a dicing die bonding film 50 (see Figure 5B ) As the dicing tape 20 and the dicing die-bonding film 50 , commercially available products can be used respectively.

[0240] 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.

[0241] In the post-process, for example, a wafer (semiconductor wafer W) as a substrate having a circuit surface formed thereon is cut into small semiconductor chips X (die), and then the semiconductor integrated circuit (semiconductor device) is assembled by bonding the semiconductor chips X to be small pieces to an adherend.

[0242] Hereinafter, regarding specific examples of the method for manufacturing a semiconductor device, first to third examples will be described in detail.

[0243] 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.

[0244] "First Example of Method for Manufacturing a Semiconductor Device"

[0245] 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.

[0246] The above-mentioned assembly process at least includes: a process (protection process) of superimposing a protective layer 11 for protecting the circuit component on at least one surface of the semiconductor wafer W to protect the circuit surface (protected surface) on which any circuit component is formed; a back grinding process of grinding the surface of the semiconductor wafer W on which the circuit component is not arranged to reduce the thickness of the semiconductor wafer W in a state where the semiconductor wafer W, the protective layer 11, the adhesive layer 13, and the base layer 15 are stacked; and a process of attaching the stack of the semiconductor wafer W, the protective layer 11, the adhesive layer 13, and the base layer 15 with the thickness reduced to the chip bonding sheet 30 in such a manner that the semiconductor wafer W is connected to the chip bonding sheet 30 (fixing process). The invention further comprises the steps of: a step of removing the adhesive layer 13 and the base layer 15 by peeling off the protective layer 11 and the adhesive layer 13 (peeling step); a step of producing a plurality of small pieces of a stacked product consisting of a semiconductor chip X formed by the semiconductor wafer W being sliced, small pieces 11' of the protective layer, and small pieces 30' of the chip bonding sheet 30 by cutting the stacked product of the semiconductor wafer W, the protective layer 11, and the chip bonding sheet 30 into small pieces at intervals in the surface direction; a step of removing each small piece 11' of the protective layer overlapping the circuit surface of the semiconductor chip X by bringing each small piece 11' of the protective layer into contact with a liquid containing water (removal step); and a step of bonding the semiconductor chip X to an adherend.

[0247] The assembling process of the first example includes the following steps, for example.

[0248] Specifically, the assembly process of the first example includes: a protection process, in which the circuit surface is protected by sticking the protection layer 11 on the circuit surface of the semiconductor wafer W; the above-mentioned back grinding process; a fixing process, in which the semiconductor wafer W having the circuit components formed on one side is stuck to the dicing chip bonding film 50 (the chip bonding sheet 30 overlapping the dicing tape 20), and the semiconductor wafer W is fixed to the dicing chip bonding film 50; the above-mentioned peeling process; a blade cutting process, in which the chip bonding sheet 30, the semiconductor wafer W, the protection layer 11 and the adhesive layer 13 are cut into small pieces by a cutting blade T or the like. The semiconductor chip X (die) is obtained by cutting the semiconductor wafer W into small pieces (the process of producing a plurality of small pieces of the above-mentioned laminate); a removing process of removing a plurality of small pieces 11' attached to the protective layer of the semiconductor chip X (the above-mentioned removing process); a picking process of peeling off the dicing tape 20 and the small piece 30' of the die bonding sheet to take out the semiconductor chip X in a state of being attached with the small piece 30' of the die bonding sheet; 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 (the above-mentioned bonding process).

[0249] 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.

[0250] 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.

[0251] 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.

[0252] In the protection process, for example, Figure 3A As shown, a protective layer 11 is stacked on the circuit surface of the semiconductor wafer W. In the protection step, for example, the protective layer 11 is stacked on the circuit surface, and the protective layer 11 is pressed against the semiconductor wafer W via the adhesive layer 13 and the base layer 15, thereby attaching the protective layer 11 to the circuit surface.

[0253] 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 removing the protective layer 11. 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.

[0254] During the back grinding process, Figure 3B As shown, grinding (back grinding) using a grinding pad K is performed until the semiconductor wafer W reaches a predetermined thickness. By grinding, the thickness of the semiconductor wafer W is reduced to a predetermined thickness (see Figure 3C ).

[0255] In the back grinding process, the semiconductor wafer W can be ground while the protective layer 11, the adhesive layer 13, and the base layer 15 are attached to the semiconductor wafer W. The force applied during the grinding process is transmitted to the protective layer 11 and the adhesive layer 13 via the semiconductor wafer W, but the adhesive force of the protective layer 11 and the adhesive force of the adhesive layer 13, which is greater than the adhesive force of the protective layer 11, can suppress the occurrence of peeling at any interface between the semiconductor wafer W and the base layer 15. In other words, the protective sheet 1 of this embodiment can be used in place of the back grinding tape generally used in the back grinding process in the state where the release liner 17 is removed. In other words, even if a normal back grinding tape is not used separately, the grinding process as described above can be performed by using a part of the protective sheet 1 of this embodiment.

[0256] In the fixing process, Figure 3D As shown, the dicing ring R is attached to the adhesive sheet 22 of the dicing tape 20, and the semiconductor wafer W is attached to the die bonding sheet 30 superimposed on the dicing tape 20. For example, the semiconductor wafer W is fixed to the dicing die bonding sheet in this way.

[0257] After the fixing process and before the stripping process, as needed, such as Figure 3E As shown, the adhesive layer 13 can be subjected to a curing treatment. A specific example of the curing treatment is an irradiation treatment with active energy rays (ultraviolet rays, etc.). By irradiation treatment with active energy rays such as ultraviolet rays, for example, the above-mentioned cross-linked acrylic copolymers can be cross-linked with each other. As a result, the adhesive force of the adhesive layer 13 can be reduced after the irradiation treatment compared to before the irradiation treatment. In addition, the adhesive layer 13 and the base layer 15 can be more easily peeled off from the protective layer 11.

[0258] When ultraviolet rays or the like are used as the active energy rays, ultraviolet rays of a wavelength that promotes the curing of the adhesive layer 13 and does not promote the hydrophilization of the protective layer 11 can be selected. This can prevent the hydrophilicity of the protective layer 11 from being unintentionally increased excessively.

[0259] It should be noted that if Figure 3FAs shown, by adopting the above-mentioned two-layer structure of the adhesive layer 13, it is possible to suppress the unintentional hydrophilization of the protective layer 11 by the irradiation of the active energy ray during the curing process. In detail, even if the active energy ray is irradiated from the first adhesive layer 13A toward the protective layer 11, the transmission of the active energy ray is suppressed by the second adhesive layer 13B containing a scattering agent or an absorbing material for the active energy ray. Therefore, the active energy ray reaching the protective layer 11 is reduced. Thus, in the case where the protective layer 11 contains the above-mentioned ion-generating compound, the hydrophilization of the protective layer 11 due to the active energy ray can be suppressed. In other words, the first adhesive layer 13A and the second adhesive layer 13B are subjected to a curing process by irradiation with active energy rays, and the unintentional hydrophilization of the protective layer 11 can be suppressed.

[0260] In the stripping process, Figure 3G and Figure 3H As shown, by peeling between the protective layer 11 and the adhesive layer 13, the adhesive layer 13 and the base material layer 15 are removed.

[0261] In blade cutting operations, e.g. Fig. 3I As shown, the semiconductor wafer W is cut. Before the blade cutting process, after the dicing ring R is attached to the adhesive sheet 22 of the dicing tape 20, the dicing ring R may be fixed to the holder H of the expansion device.

[0262] Specifically, the semiconductor wafer W and the chip bonding sheet 30 are cut into a predetermined size together to form a semiconductor chip X having a chip bonding sheet 30'. The blade cutting process is performed in a conventional manner, for example, using a cutting blade T. In the blade cutting process, for example, a cutting method called full cutting can be adopted, which cuts into the chip bonding sheet 30. There is no particular limitation on the cutting device used in the blade cutting process, and a conventionally known device can be used.

[0263] 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.

[0264] In the removal process, as needed, such as Figure 3J As shown, the above-mentioned hydrophilic treatment can be applied to each small piece 11' of the protective layer. As the hydrophilic treatment, an irradiation treatment with active energy rays is used. By applying the hydrophilic treatment to each small piece 11' of the protective layer containing the above-mentioned ion generating compound, the above-mentioned ion generating compound in each small piece 11' generates an acid or a base, thereby improving the hydrophilicity of each small piece 11'. As a result, when the small piece 11' is subsequently in contact with a liquid containing water, the small piece 11' can be more easily removed from the surface of the semiconductor chip X.

[0265] In the active energy ray irradiation treatment in the removal step, ultraviolet rays having an intensity of 10 mW to 300 mW are used as active energy rays, and the plurality of small pieces 11 ′ of the protective layer are irradiated with ultraviolet rays to give an energy of 50 mJ to 1000 mJ.

[0266] In the removal process, Figure 3K 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.

[0267] 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 relatively easily, and the amount of foreign matter adhering to the surface of the semiconductor chip X can be relatively easily reduced 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.

[0268] 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.

[0269] 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.

[0270] 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, isopropanol, or butanol such as tert-butyl alcohol may be cited.

[0271] 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.

[0272] In the picking process, Figure 3LAs shown, the semiconductor chip X and the small piece 30' of the die bonding sheet are peeled off from the adhesive sheet 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.

[0273] When the pickup process is performed in this way, the small piece 30' of the die bond sheet attached to the semiconductor chip X needs to be easily peeled off from the adhesive sheet 22 of the dicing tape 20. The dicing tape 20 described above is designed to exhibit such performance well.

[0274] For example, the dicing tape 20 is configured such that, by irradiating active energy rays (e.g., ultraviolet rays), the adhesive sheet 22 is cured and the adhesive force of the adhesive sheet 22 is reduced. By curing the adhesive sheet 22 after irradiation, the adhesive force of the adhesive sheet 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 sheet 22. Dicing tapes 20 having such a configuration are already commercially available.

[0275] 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 3M As shown, the semiconductor chip X in a state where the small pieces 30 ′ of the die bonding sheet are attached to each other may be stacked multiple times.

[0276] 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.

[0277] 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.

[0278] 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.

[0279] “Method for manufacturing a semiconductor device according to the second example”

[0280] 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.

[0281] The manufacturing method of the semiconductor device of the second example comprises, for example, a half-cutting process step, in which grooves are formed 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 protection process step, in which a protection layer 11 is attached to the circuit surface of the semiconductor wafer W to protect the circuit surface, so that the semiconductor wafer W, the protection layer 11, the adhesive layer 13, and the base layer 15 are stacked; a back grinding process step, in which a grinding process is performed on the surface on the opposite side of the circuit surface of the semiconductor wafer W in a state where the protective layer 11, the adhesive layer 13, and the base layer 15 overlap, so that the thickness of the semiconductor wafer W is reduced; a fixing process step, in which the protective layer 11, the adhesive layer 13, and the base layer 15 are fixed to the circuit surface of the semiconductor wafer W. The semiconductor wafer W with a reduced thickness is affixed to the dicing tape 20 to fix the semiconductor wafer W to the dicing tape 20; a peeling process is performed between the adhesive layer 13 and the protective layer 11 to remove the adhesive layer 13 and the base layer 15; an expansion process is performed to break the semiconductor wafer W and the protective layer 11 into small pieces by stretching the dicing tape 20; a removal process is performed to remove the plurality of small pieces 11' affixed to the protective layer of the semiconductor chip X; a picking process is performed to peel off the small piece 30' of the chip bonding sheet affixed with the semiconductor chip X from the adhesive sheet 22 of the dicing tape 20 to take out the semiconductor chip X; and a bonding process is performed to bond the taken-out semiconductor chip X to an adherend.

[0282] In the second example, for example, Figure 4A and Figure 4B As shown, a wafer processing tape E is attached to the surface of the semiconductor wafer W opposite to the protected surface. Specifically, the wafer processing tape E is attached to the surface of the semiconductor wafer W opposite to the circuit surface. In the state where the wafer processing tape E is attached, a dividing groove for dividing the semiconductor wafer W into small pieces is formed. The groove is formed in the semiconductor wafer W in a manner that does not penetrate in the thickness direction.

[0283] The protective layer 11 of the protective sheet 1 is superimposed on the circuit surface of the semiconductor wafer W having the grooves formed thereon, and the protected surface (circuit surface) is protected by the protective layer 11. Figure 4C As shown in FIG. 1 , a laminate of a protective layer 11, an adhesive layer 13, and a base layer 15 is laminated on the circuit surface of a semiconductor wafer W. While the protective layer 11, the adhesive layer 13, and the base layer 15 are being laminated, the wafer processing tape E (see FIG. 1 ) that is initially laminated is peeled off. Figure 4D). With the protective layer 11, adhesive layer 13, and base layer 15 of the protective sheet 1 attached, grinding is performed on the surface of the semiconductor wafer W where no circuit components are configured. For example, grinding (back grinding) using a grinding pad K is performed until the semiconductor wafer W reaches a predetermined thickness (see Figure 4E and Figure 4F ). Through grinding, the thickness of the semiconductor wafer W is reduced to a predetermined thickness.

[0284] 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 4G and Figure 4H ). At this time, if Figure 4H As shown in FIG. 1 , a protective layer 11 is attached to the circuit surface of the semiconductor wafer W, and further, an adhesive layer 13 and a base layer 15 are attached to the protective layer 11. Then, the protective layer 11 and the adhesive layer 13 are peeled off by a peeling process, and the adhesive layer 13 and the base layer 15 are removed (see FIG. 1 ). Fig. 4I ).

[0285] Before removing the adhesive layer 13 and the base layer 15 , as described above, the adhesive layer 13 is preferably subjected to a curing treatment by irradiation with active energy rays or the like in order to reduce the adhesive force of the adhesive layer 13 .

[0286] 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 4J As 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 semiconductor wafer W and the protective layer 11 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, the semiconductor wafer W and the protective layer 11 are broken into small pieces under specific temperature conditions. The above-mentioned temperature conditions are, for example, above -20°C and below 0°C. The expanded state (so far, it is a low-temperature expansion process) is released by lowering the push-up member U.

[0287] When the expansion process is performed at a low temperature, the protective layer 11 needs to be cut and divided into small pieces. The protective layer 11 is designed to be well cut at this time.

[0288] 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).

[0289] In the expansion process, the semiconductor wafer W is cut into small pieces while the semiconductor wafer W and the protective layer 11 are stacked to produce semiconductor chips X. At this time, foreign matter such as fragments may be generated by cutting the semiconductor wafer W, but the protective layer 11 can prevent the foreign matter from adhering to the circuit surface of the semiconductor chip X.

[0290] Afterwards, by the same method as above, Figure 4K As shown, the above-mentioned hydrophilic treatment may be performed on the small piece 11 ′ of the protective layer as required.

[0291] Furthermore, the small piece 11' of the protective layer attached to the semiconductor chip X can be removed by the removal step in the same manner as the above-mentioned method (see Figure 4L ) In addition, by the same method as the above method, 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 implemented.

[0292] 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.

[0293] That is, various modes used in a general method for manufacturing an electronic device may be adopted within a range that does not impair the effects of the present invention.

[0294] Matters disclosed by this specification include the following. (1)

[0296] A protective sheet comprises: a protective layer for protecting at least a portion of the surface of a substrate as a protected object; a base layer arranged opposite to one side of the protective layer; an adhesive layer arranged between the protective layer and the base layer and adhered to the protective layer and the base layer in a manner that each side thereof can be peeled off; and a peeling liner overlapping the other side of the protective layer, wherein the protective layer comprises a hydrophilic polymer having a hydrophilic group in its molecule.

[0297] The protective sheet includes a protective layer that can be relatively easily removed from the surface of a substrate to be protected by contact with a liquid containing water, and can also be used for grinding of the substrate in a back grinding step. (2)

[0299] The protective sheet according to the above (1), wherein the protective layer further contains a compound that generates an acid or a base upon at least one of heating and irradiation with active energy rays. (3)

[0301] The protective sheet according to (1) or (2) above, wherein the hydrophilic group of the hydrophilic polymer is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a pyrrolidone group, and a polyoxyethylene group. (4)

[0303] The protective sheet according to any one of (1) to (3) above, wherein the hydrophilic polymer is at least one selected from the group consisting of polyvinyl alcohol, a water-soluble polyester polymer, and polyoxyethylene. (5)

[0305] The protective sheet according to any one of (1) to (4) above, wherein the adhesive layer comprises an acrylic copolymer having a plurality of different (meth)acrylic acid alkyl ester units as monomer units in a molecule, or having a (meth)acrylic acid alkyl ester unit and a monomer unit other than the (meth)acrylic acid alkyl ester unit in a molecule. (6)

[0307] The protective sheet according to any one of (1) to (4) above, wherein the adhesive layer contains a cross-linkable polymer compound that undergoes a cross-linking reaction by curing treatment. (7)

[0309] The protective sheet according to the above (6), wherein the adhesive layer contains a cross-linkable acrylic copolymer as the cross-linkable polymer compound, and the cross-linkable acrylic copolymer has at least a (meth)acrylic acid alkyl ester unit and a cross-linkable group-containing (meth)acrylic acid ester unit as monomer units in the molecule.

[0310] Example

[0311] Next, the present invention will be described in further detail by means of experimental examples, but the present invention is not limited thereto.

[0312] The protective sheet is made in the following manner. Specifically, a composition for making a protective layer containing a solvent is applied to one side of a release liner, and the solvent is volatilized, thereby laminating the protective layer and the release liner. On the other hand, a composition for making an adhesive layer containing a solvent is applied to one side of a substrate layer, and the solvent is volatilized, thereby laminating the adhesive layer and the substrate layer. Furthermore, the protective layer and the adhesive layer are laminated in a manner such that the protective layer and the adhesive layer are sandwiched between the release liner and the substrate layer. In this way, a protective sheet having a protective layer and an adhesive layer disposed between the release liner and the substrate layer is manufactured.

[0313] (Raw material for protective layer)

[0314] PVA-1: polyvinyl alcohol (commercially available product).

[0315] The saponification degree was 65 (mol %) and the average polymerization degree was 240.

[0316] PVA-2: polyvinyl alcohol (commercially available product).

[0317] The saponification degree was 35 (mol %) and the average polymerization degree was 200.

[0318] Ion generating compound (photoacid generator): sulfonium salt type (product name: "CIP-200K", manufactured by San-Apro Corporation).

[0319] The details of each example and comparative example are as follows.

[0320] [Example 1]

[0321] (Production of protective layer)

[0322] Polyvinyl alcohol (PVA-1 described above) was dispersed in water and then heated to 90° C. to dissolve the polyvinyl alcohol, thereby preparing a PVA aqueous solution.

[0323] 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. The surface was then dried at 110° C. for 2 minutes to prepare a protective layer having a thickness of 10 μm that overlapped one surface of the release liner.

[0324] (Production of Adhesive Layer)

[0325] First, the following raw material monomers of the acrylic copolymer were prepared.

[0326] · 2-Hydroxyethyl acrylate (HEA): 11 parts by mass.

[0327] · 2-Ethylhexyl acrylate (2EHA): 89 parts by mass.

[0328] The above raw materials are added to a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer and a stirring device. 0.2 weight parts of azobisisobutyronitrile (AIBN) is used as a thermal polymerization initiator relative to a total of 100 weight parts of monomers. Ethyl acetate is added as a reaction solvent in a manner such that the concentration of all monomers becomes a specified concentration (e.g., 36 weight %). The polymerization reaction is treated for a specified time (e.g., 4 hours) at 62° C. in a nitrogen stream, and further for a specified time (e.g., 2 hours) at 75° C. to obtain an intermediate of an acrylic copolymer.

[0329] In the liquid containing the intermediate of the acrylic copolymer prepared as described above, 13 parts by mass of 2-methacryloyloxyethyl isocyanate (hereinafter also referred to as MOI) was added in a molar conversion manner to 80 mol% relative to the total amount of HEA. In addition, 0.07% by mass of dibutyltin dilaurate was added as a reaction catalyst relative to 100 parts by mass of the acrylic copolymer. Thereafter, an addition reaction treatment (urethanization reaction treatment) was performed at 50° C. for 12 hours in an air flow to obtain an acrylic copolymer.

[0330] Next, the following ingredients were added to 100 parts by mass (solid content) of the acrylic copolymer to prepare a composition for forming an adhesive layer.

[0331] Photopolymerization initiator: 5 parts by mass.

[0332] (Product name: "Omnirad 127", manufactured by IGM.)

[0333] Polyisocyanate compound: 0.8 parts by mass.

[0334] (Product name: "Takenate D-101A", manufactured by Mitsui Chemicals, Inc.)

[0335] The adhesive layer composition prepared as described above was applied to a release sheet, and heated and dried at 120°C for 2 minutes to produce an adhesive layer with a thickness of 30 μm. After that, the exposed surface of the adhesive layer produced on the release sheet was bonded to the primer-treated surface of the substrate layer (PET film, thickness 50 μm) using a laminator at room temperature, and further allowed to stand at 50°C for 24 hours to produce a laminate of the adhesive layer and the substrate layer. The adhesive layer at this stage was cured by curing treatment (hereinafter referred to as "curability").

[0336] Thereafter, after removing the release sheet, the adhesive layer and the protective layer were bonded together using a laminating roller at 40° C. and 10 mm / s.

[0337] For the curable protective layer prepared as described above, the accumulated light intensity was 300 mJ / cm 2 The protective layer is not cured by the curing treatment, so it is indicated as "non-curable" in Table 1.

[0338] [Example 2]

[0339] (Production of protective layer)

[0340] A protective sheet was prepared in the same manner as in Example 1 except that PVA-2 was used instead of PVA-1 and 3 parts by mass of the photoacid generator was added and mixed to the PVA aqueous solution prepared in Example 1 based on 100 parts by mass of the PVA polymer.

[0341] (Production of Adhesive Layer)

[0342] In the same manner as the adhesive layer of Example 1, an adhesive layer was produced.

[0343] [Example 3]

[0344] (Production of protective layer)

[0345] In the same manner as in Example 1, an adhesive layer was produced.

[0346] (Production of Adhesive Layer)

[0347] An adhesive layer was produced in the same manner as the method for producing an adhesive layer in Example 1, but without performing a curing treatment by ultraviolet irradiation, a curable adhesive layer was produced.

[0348] [Example 4]

[0349] (Production of protective layer)

[0350] A protective sheet was prepared in the same manner as in Example 1 except that PVA-2 was used instead of PVA-1 and 3 parts by mass of the photoacid generator was added and mixed to the PVA aqueous solution prepared in Example 1 based on 100 parts by mass of the PVA polymer.

[0351] (Production of Adhesive Layer)

[0352] An adhesive layer was produced in the same manner as the method for producing an adhesive layer in Example 1, but without performing a curing treatment by ultraviolet irradiation, a curable adhesive layer was produced.

[0353] [Comparative Example]

[0354] (Production of protective layer)

[0355] The protective layer was formed by the same method as the adhesive layer of Example 1, but the above-mentioned curing treatment by ultraviolet irradiation was not performed, and the layer was different from the adhesive layer of Example 1 in that it was hardenable.

[0356] In the acrylic copolymer in the protective layer, substantially no hydroxyl group remains.

[0357] (Production of Adhesive Layer)

[0358] In the same manner as the adhesive layer of Example 1, an adhesive layer was produced.

[0359] The performance of the protective sheet was evaluated by simulation tests as described below.

[0360] <Fixing process and protection process>

[0361] The release liner was peeled off and removed from the protective sheet manufactured by each embodiment and comparative example, so that one surface of the protective layer was exposed. The exposed surface was bonded to the surface of the silicon bare wafer (substrate) at a bonding speed of 10 mm / s while being heated to 90°C. After bonding, a portion of the protective sheet that protruded outward from the edge of the disc-shaped silicon bare wafer was removed. In this way, the silicon bare wafer, the protective layer, the adhesive layer, and the substrate layer were stacked in sequence.

[0362] <Peeling process>

[0363] The adhesive layer was cured as needed. Specifically, the "curable" adhesive layer was irradiated with ultraviolet light of 300 mJ for 7 seconds to cure. After that, the protective layer and the adhesive layer were peeled off to remove the adhesive layer and the substrate layer.

[0364] <Removal process>

[0365] The protective layer is subjected to a hydrophilic treatment as required. Specifically, the protective layer containing a photoacid generator is irradiated with ultraviolet light at an intensity of 300 mJ for 7 seconds to perform a hydrophilic treatment to increase the hydrophilicity of the protective layer.

[0366] Thereafter, in order to remove the protective layer, the stack of the silicon bare wafer and the protective layer was immersed in water at 25° C. for 30 seconds.

[0367] <Water absorption rate of protective layer before and after UV irradiation>

[0368] The water absorption rate of the protective layer was measured by Karl Fischer / coulometric titration using a moisture measuring device (product name "CA-07") and a moisture vaporization device (product name "VA-07") manufactured by Mitsubishi Chemical Analytical Technology Co., Ltd. Specifically, a test sample of the protective layer weighing about 4 mg was placed in a steady state at 23°C and 50 RH%. After that, the moisture of the test sample was evaporated by heating it at 150°C for 3 minutes using a moisture vaporization device, and the amount of vaporized moisture was measured. Furthermore, the mass of the heated test sample was measured.

[0369] The water absorption rate was calculated from the ratio of the measured water content to the mass of the heated test sample (in an absolutely dry state).

[0370] <Evaluation: Ease of removal of protective layer (after hydrophilization treatment of protective layer by ultraviolet irradiation)>

[0371] After the above-mentioned removal process is carried out, the water used to remove the protective layer is removed. Furthermore, the surface of the silicon bare wafer is analyzed by Fourier transform infrared spectrophotometer (FT-IR). Through the above analysis, it is confirmed whether there is residual organic matter. It should be noted that the evaluation criteria for the simplicity of removing the protective layer are as follows.

[0372] (Good) Almost no residual organic matter was found (800-4000cm －1 The maximum absorption at is below 0.05).

[0373] (Bad) Residual organic matter was confirmed (800-4000cm －1 The maximum absorption at the point is greater than 0.05).

[0374] Table 1 shows the evaluation results of the tests conducted as above.

[0375] [Table 1]

[0376]

[0377] The above evaluation results show that the protective sheet can suppress the adhesion of foreign matter to the protected surface of the semiconductor chip (die), thereby protecting the protected surface. In addition, the protective layer can be removed relatively easily with water.

[0378] In addition, before the curing treatment and the hydrophilization treatment are implemented, the peeling force between the protective layer and the adhesive layer in the protective sheet and the peeling force between the adhesive layer and the base layer are large. In addition, the adhesion of the protective layer to the substrate (silicon wafer) is also high. Therefore, even if shearing force is applied during the back grinding process, it can be said that it is not easy to peel off between the protective layer and the adhesive layer and between the adhesive layer and the base layer. In addition, it can be said that it is not easy for the protective layer to detach from the protected surface of the substrate. Therefore, instead of the usual back grinding tape, the protective sheet of the embodiment is used, and the back grinding process can be implemented.

[0379] By using the protective sheet of the above-mentioned embodiment to manufacture a semiconductor device, the protective sheet can be used instead of the back grinding tape to perform back grinding on the semiconductor wafer. There is no need to use the back grinding tape separately and remove the back grinding tape after the back grinding process, so semiconductor devices can be manufactured efficiently. In addition, after the substrate such as the semiconductor chip is protected by the protective sheet, the protective sheet can be easily removed by a liquid containing water. Therefore, it is not easy for a part of the protective sheet to remain on the surface of the protected substrate.

[0380] Industrial Applicability

[0381] 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.

[0382] Description of Reference Numerals

[0383] 1: protective sheet; 11: protective layer; 11': small piece of protective layer; 13: adhesive layer; 15: substrate layer; 17: release liner; 20: dicing tape; 21: substrate sheet; 22: adhesive sheet; 30: chip bonding sheet; 50: dicing chip bonding film; W: semiconductor wafer; X: semiconductor chip.

Claims

1. A protective sheet comprising: A protective layer for protecting at least a portion of a surface of a substrate as a protected object; A substrate layer is disposed opposite to one surface of the protective layer; an adhesive layer disposed between the protective layer and the base layer and bonded to the protective layer and the base layer in a manner that each surface on both sides can be peeled off; and a release liner, overlapping the other side of the protective layer, The protective layer has a structure including a hydrophilic polymer having a hydrophilic group in a molecule, and when the protective layer comes into contact with a liquid including water, at least a portion of the protective layer is dissolved and removed from the surface of the substrate.

2. The protective sheet according to claim 1, wherein: The protective layer further includes a compound that generates an acid or a base by at least one of heating and irradiation with active energy rays.

3. The protective sheet according to claim 1 or 2, wherein: The adhesive layer includes a cross-linkable polymer compound that undergoes a cross-linking reaction by curing.

4. The protective sheet according to claim 1 or 2, wherein: The hydrophilic group of the hydrophilic polymer is at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfonic acid group, a pyrrolidone group, and a polyoxyethylene group.

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