Protective sheet and method for manufacturing electronic device

Abstract

Provided is a protective sheet provided with a protective layer to be bonded to a surface to be protected of an electronic device having the surface to be protected, or to a surface to be protected of an electronic device connected body obtained by connecting a plurality of electronic devices, the mass reduction rate WW of the protective layer after being immersed in water at 25 DEG C for 180 seconds is 0-30 mass%, and the mass reduction rate WS of the protective layer after being immersed in an alcohol aqueous solution at 25 DEG C having an alcohol concentration of 55 mass% for 180 seconds is 40-100 mass%.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority from Japanese Patent Application No. 2023-055134, which is hereby incorporated by reference herein in its entirety. TECHNICAL FIELD

[0003] The present application relates to a protective sheet and a manufacturing method of an electronic device. For example, the present application relates to a manufacturing method of a protective sheet and an electronic device using the protective sheet, the protective sheet to be attached to a protection target surface or the like of an electronic device bonded body obtained by bonding a plurality of electronic devices. BACKGROUND

[0004] Conventionally, as an electronic device bonded body, for example, a semiconductor wafer, a wafer level package, or an image sensor package is known. By dividing these electronic device bonded bodies, an electronic device is obtained.

[0005] A semiconductor chip as an electronic device is obtained, for example, by dicing a semiconductor wafer as an electronic device bonded body and singulating (dividing) into individual semiconductor chips (for example, Patent Literature 1).

[0006] The semiconductor wafer described in Patent Literature 1 has a semiconductor wafer main body and an electrode portion each arranged to sandwich the semiconductor wafer main body in the thickness direction. In the semiconductor wafer, a circuit formation surface is formed on each of both surfaces of the semiconductor wafer main body. A plurality of circuits including elements such as transistors or wiring or the like are generally formed on the circuit formation surfaces. Each circuit of the circuit formation surface of the semiconductor wafer has one or a plurality of pairs of electrode portions as described above. By dicing such a semiconductor wafer, a plurality of semiconductor chips having a semiconductor chip main body, at least one circuit, and at least two electrode portions are obtained.

[0007] The semiconductor chip described in Patent Literature 1 obtained as described above is used, for example, by mounting the electrode portion arranged on one surface to the electrode portion of a circuit board and mounting the electrode portion arranged on the other surface to the electrode portion of another semiconductor chip.

[0008] Further, the wafer level package as the electronic device bonded body described above has a circuit board and a plurality of semiconductor packages mounted on one surface of the circuit board. The wafer level package as described above is generally singulated (divided) into individual semiconductor packages as electronic devices by dicing or the like.

[0009] Further, the image sensor package layered body as described above has, for example, a sensor wafer main body having a plurality of circuits formed on one surface side, and a glass plate having substantially the same size as the sensor wafer main body in plan view, and configured to cover one surface (a surface on which the plurality of circuits are formed) side of the sensor wafer main body, and fixed by an adhesive layer composed of an adhesive or a glass frit or the like.

[0010] Further, the image sensor package layered body is singulated (divided) into individual image sensor packages each including at least one circuit by cutting or the like.

[0011] Prior Art Documents

[0012] Patent Documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2015-170754 SUMMARY

[0014] PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] Further, in a case where an electronic device bonded body (for example, a semiconductor wafer) as a cutting target is cut by blade cutting processing using a cutting blade (cutting abrasive tool), heat is generated due to abrasion of the cutting blade when the cutting target is cut with the cutting blade, or cutting chips are generated along with cutting of the cutting target. Therefore, in order to suppress the heat or to remove the cutting chips, a surface (hereinafter also referred to as a cutting start surface) on a side into which the cutting blade of the cutting target is cut is sprayed with cooling water in the blade cutting processing.

[0016] In spraying the cooling water, in order to suppress the cutting chips generated along with the cutting of the cutting target from adhering to the cutting start surface of the cutting target, the blade cutting processing is sometimes performed in a state where the cutting start surface is covered with a protective layer. Ideally, the protective layer covering the cutting start surface does not peel off due to the cooling water when the blade cutting processing is thus performed, that is, the protective layer is sufficiently retained on the cutting start surface. On the other hand, after the blade cutting processing of the cutting target is completed, the protective layer covering the cutting start surface is sprayed with a solution containing a liquid different from water, such as an organic solvent such as alcohol, to remove the protective layer from the cutting start surface. Therefore, ideally, the protective layer is easily peeled off from the cutting start surface after the blade cutting processing is performed on the cutting target.

[0017] However, as for the protective sheet having a protective layer that can balance sufficient retention of the cutting target in the blade cutting processing and easy peeling from the cutting target after the blade cutting processing, it is difficult to say that sufficient research has been conducted thereon.

[0018] Therefore, the technical problem of the present invention is to provide a protective sheet having a protective layer that provides sufficient retention of the object being cut during blade cutting and can be easily peeled off from the object being cut after blade cutting.

[0019] Furthermore, the technical problem of the present invention is to provide a method for manufacturing an electronic device, and more specifically, to provide a method for manufacturing an electronic device using the protective layer described above.

[0020] Solution for solving the problem

[0021] That is, the protective sheet of the present invention has a protective layer, which is to be attached to the protective surface of an electronic device having a protected surface, or to the protective surface of an electronic device connector obtained by connecting multiple electronic devices. The mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds is... W The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds, where the mass is more than 0% by mass and less than 30% by mass. S It is 40% or more by mass and less than 100% by mass.

[0022] Furthermore, the manufacturing method of the electronic device of the present invention uses a protective sheet having a protective layer having at least a portion of the surface to be attached to an electronic device connector, and manufactures an electronic device from the electronic device connector having the protective layer attached. The manufacturing method of the electronic device includes the following steps: attaching the protective layer to an electronic device connector obtained by connecting multiple electronic devices having protected surfaces in such a way that the protected surfaces face in the same direction; dividing the electronic device connector with the protective layer attached while washing it with water to obtain multiple electronic devices having multiple divided protective layers attached; and removing the divided protective sheet from each protected surface of the multiple electronic devices, and immersing the protective layer in water at 25°C for 180 seconds to obtain the mass reduction rate W of the protective layer. W The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds, where the mass is more than 0% by mass and less than 30% by mass. S The content of the protective layer is 40% or more and 100% or less. When removing the segmented protective layer, at least a portion of the protective layer is dissolved by contacting the segmented protective layer with a solution containing an organic solvent at a concentration of 55% or more, thereby removing the segmented protective layer from the plurality of electronic devices. Attached Figure Description

[0023] Figure 1This is a schematic cross-sectional view showing the structure of a wafer-level package.

[0024] Figure 2A This is a schematic cross-sectional view showing the structure of an image sensor package.

[0025] Figure 2B This is a schematic cross-sectional view showing the structure of the stacked body used for image sensor packaging.

[0026] Figure 3 This is a schematic diagram illustrating an example of a semiconductor wafer having electrodes on both sides.

[0027] Figure 4 This is a schematic cross-sectional view showing the structure of a protective sheet according to one embodiment of the present invention.

[0028] Figure 5A This is a cross-sectional view schematically illustrating an example of a protective layer of a protective sheet being attached in a manufacturing method of a semiconductor chip in the form of a TSV.

[0029] Figure 5B This is a cross-sectional view illustrating an example of how a semiconductor wafer is divided in a method for manufacturing a semiconductor chip in the form of a TSV.

[0030] Figure 5C This is a cross-sectional view schematically illustrating an example of removing the protective layer of a protective sheet in a method for manufacturing a semiconductor chip in the form of a TSV.

[0031] Figure 6A This is a schematic cross-sectional view illustrating an example of grinding a semiconductor wafer.

[0032] Figure 6B This is a schematic cross-sectional view showing an example of a semiconductor wafer after grinding.

[0033] Figure 7 This is a schematic cross-sectional view illustrating the structure of a protective sheet according to another embodiment of the present invention. Detailed Implementation

[0034] Hereinafter, one embodiment of the present invention will be described.

[0035] [Protective Film]

[0036] The protective sheet of this embodiment has a protective layer, which is to be attached to the protective surface of an electronic device having a protected surface, or to the protective surface of an electronic device connector obtained by connecting multiple electronic devices.

[0037] In the protective sheet of this embodiment, the mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds relative to the mass of the protective layer before immersion in water at 25°C is... W It is between 0% and 30% by mass.

[0038] In the protective sheet of this embodiment, the mass reduction rate W of the protective layer after immersion in an alcohol-water solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds relative to the mass of the protective layer before immersion in the alcohol-water solution at 25°C is... S It is 40% or more by mass and less than 100% by mass.

[0039] It should be noted that, hereinafter, an alcohol-water solution with an alcohol concentration of 55% by mass will also be referred to as a 55% alcohol-water solution.

[0040] The inventors conducted in-depth research and discovered that, by immersing a protective layer having a protective layer on the surface to be bonded to an electronic device or the surface to be bonded to an electronic device connector in water at 25°C for 180 seconds, the mass reduction rate W W For a specific range, and the mass reduction rate W after immersing the protective layer in the alcohol-water solution at 25°C for 180 seconds. S Within a specific scope, it can solve the technical problems described above. Therefore, the present invention was conceived.

[0041] It should be noted that the mass reduction rate W of the protective layer W This value is determined by immersing the protective layer in water at 25°C for a specified time while stirring at 1000 rpm. The mass reduction rate W of the protective layer... S The value is obtained by immersing the protective layer in a 55% alcohol-water solution at 25°C for a specified time while stirring at 1000 rpm.

[0042] Specifically, the mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds relative to the mass of the protective layer before immersion in water at 25°C is... W It can be calculated in the following order.

[0043] (1) A protective layer with a thickness of 160 μm is formed on the membrane (e.g., a release liner). The 160 μm thick protective layer is formed, for example, by overlapping four protective layers with a thickness of 40 μm in the thickness direction.

[0044] (2) The protective layer, which has a thickness of 160 μm, is punched to a diameter of 9 mm to produce a cylindrical test specimen (hereinafter referred to as the cylindrical test specimen) with a diameter of 9 mm and a thickness (height) of 160 μm. Then, the cylindrical test specimen is peeled off from the membrane.

[0045] (3) Determine the mass W0 of the cylindrical test specimen.

[0046] (4) Prepare a 100-mesh metal mesh by bending a flat metal mesh at a right angle. The metal mesh has a horizontal portion extending in the horizontal direction and a vertical portion extending upward from one end of the horizontal portion. Place the cylindrical test specimen on the upper surface of the horizontal portion. Immerse the cylindrical test specimen in water at 25°C in a beaker for 180 seconds while it is placed on the metal mesh. It should be noted that the upper end of the vertical portion of the metal mesh hangs on the upper end of the side wall of the beaker. The water at 25°C is stirred beforehand using a stirrer at a stirring speed of 1000 rpm.

[0047] (5) Remove the cylindrical test specimen from the water at 25°C in the beaker, and after slightly drying it using a desiccator (pre-drying), perform formal drying at 110°C for 2 minutes. Then, measure the mass W1 of the cylindrical test specimen after formal drying.

[0048] (6) Calculate the value of [(W0-W1) / W0]×100.

[0049] (7) Perform steps (1) to (6) above on the three cylindrical test specimens, and calculate the mass reduction rate W by taking the arithmetic mean of the calculated values ​​obtained for each cylindrical test specimen. W The value of .

[0050] The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with a concentration of 55% by mass at 25°C for 180 seconds. S In this case, the liquid placed in the beaker is replaced with water at 25°C and then with an aqueous alcohol solution at 25°C (alcohol concentration 55% by mass). Otherwise, the mass reduction rate W can be considered. W Similarly, find the answer.

[0051] It should be noted that the mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with a 20% by mass alcohol concentration at 25°C for 180 seconds, as described in the example, is... S’ In this case, the liquid added to the beaker is an aqueous solution of the alcohol at 25°C (alcohol concentration 20% by mass), and in addition, it can be compared with the mass reduction rate W. W Similarly, find the answer.

[0052] Here, the mass reduction rate W W The closer the mass percentage is to 0%, the less soluble the protective layer becomes in water at 25°C. On the other hand, the mass reduction rate W... W The closer to 100% by mass, the more readily the protective layer dissolves in water at 25°C. Similarly, the mass reduction rate W... SThe closer the percentage is to 100% by mass, the more readily the protective layer dissolves in an aqueous alcohol solution at 25°C with an alcohol concentration of 55% by mass. Therefore, as described above, if the mass reduction rate W... W If the mass reduction rate is between 0% and 30% by mass, then the protective layer of the protective sheet is considered to be difficult to dissolve in water. On the other hand, if the mass reduction rate W... S If the mass reduction rate is between 40% and 100% by mass, then the protective layer of the protective sheet can be said to be relatively soluble in organic solvents such as alcohols. Regarding the protective layer of the protective sheet in this embodiment, the mass reduction rate W... W Within the above numerical range, and the mass reduction rate W S The values ​​are within the aforementioned range. Therefore, when blade cutting is performed with the protective layer attached to the surface of the electronic device connector, such as a semiconductor wafer, which is the object being cut, the protective layer is not easily peeled off even when cooling water is sprayed on it. Furthermore, after multiple electronic devices (semiconductor chips, etc.) are obtained through blade cutting, the protective layer is easily peeled off by spraying organic solvents, etc.

[0053] That is, the protective layer of the protective sheet in this embodiment can fully retain the object being cut during blade cutting and can be easily peeled off from the object after blade cutting. It should be noted that the temperature of the cooling water used during blade cutting is usually below 25°C.

[0054] Examples of such electronic devices include semiconductor chips or circuit boards. Examples of such electronic device connectors include semiconductor wafers for obtaining the semiconductor chip, or connecting circuit boards that connect multiple circuit boards.

[0055] Examples of connectors for the electronic devices include dummy wafers, which include: a support substrate; and a package formed by sealing multiple semiconductor chips together with resin while they are disposed on the support substrate. The dummy wafer can also be the package removed from the support substrate. A redistribution layer can be formed on at least one surface of the dummy wafer. In this case, a protective layer of a protective sheet can be used to protect the redistribution layer. It should be noted that the dummy wafer segments obtained by dividing the dummy wafer into constituent units each including at least one semiconductor chip are classified as electronic devices.

[0056] Examples of connectors for the aforementioned electronic devices include: Figure 1 The example shown is a wafer-level package (WLP). Figure 1As shown, a wafer-level package 100 includes a circuit board 110 and a plurality of semiconductor packages 120 mounted on the circuit board 110. In the wafer-level package 100, each of the plurality of semiconductor chips is sealed with resin on the circuit board 110. In the wafer-level package 100, the surface of each of the plurality of semiconductor packages 120 (the surface opposite to the surface mounted on the circuit board 110) can be formed by one surface of a glass sheet 120a. That is, in the wafer-level package 100, each of the plurality of semiconductor packages 120 can have a glass sheet 120a on its surface side (the side opposite to the surface mounted on the circuit board 110). When the wafer-level package 100 is configured in this way, the protective layer of the protective sheet is used to protect one surface of each glass sheet 120a in the plurality of semiconductor packages 120.

[0057] It should be noted that the wafer-level package 100 follows the... Figure 1 The cut line L shown is divided by cutting, etc., and monolithically (cut) into individual semiconductor packages. The individual semiconductor packages obtained by monolithizing the wafer-level package 100 are classified as electronic devices.

[0058] Examples of such electronic devices include: Figure 2A The image sensor package 200 shown includes: a sensor chip body 210 with circuitry formed on one surface; and a glass sheet 230 (protective glass, cover glass) laminated to one surface of the sensor chip body 210 (the surface with the circuitry formed) via an adhesive layer 220 made of adhesive or glass frit. The image sensor package 200 is used, for example, as an imaging element in a camera or similar device.

[0059] In the image sensor package 200 configured as described above, the protective layer of the protective sheet is used to protect the surface of the glass sheet 230 (the side opposite to the side closest to the sensor chip body 210) that is stacked on the sensor chip body 210.

[0060] It should be noted that the image sensor package 200 is typically constructed by means of, for example, Figure 2BThe image sensor package shown is obtained by dividing the stack 200' into multiple image sensor packages 200. Specifically, the image sensor package stack 200' includes: a sensor wafer body 210' with multiple circuits formed on one surface; and a glass plate 230' having approximately the same dimensions as the sensor wafer body 210' when viewed from above, and is stacked on one surface of the sensor wafer body 210' (the surface with the multiple circuits) across an adhesive layer 220' made of adhesive or glass frit, etc. The image sensor package stack 200' is divided by cutting or other processes to create individual image sensor packages 200, each including at least one circuit. Specifically, along as shown... Figure 2B The cut line L' shown is used to divide the image into individual image sensor packages 200.

[0061] As described above, since the image sensor package stack 200' is composed of multiple image sensor packages 200, it is classified as an electronic device connector.

[0062] The semiconductor chip typically includes: a semiconductor chip body; and electrode portions disposed on at least one side of the semiconductor chip body. The electrode portions are electrically connected, for example, to electrode portions of other components. In the semiconductor chip, a circuit is formed on at least one side of the semiconductor chip body, and the surface where the circuit is formed is called the circuit forming surface. It should be noted that other components described above may include, for example, a circuit board, or other semiconductor chips constructed in the same manner as the semiconductor chip.

[0063] Examples of semiconductor chips include those in the form of TSV (Through Silicon Via). A TSV-type semiconductor chip includes: electrode portions disposed on both sides of the semiconductor chip body in a manner that clamps the semiconductor chip body in the thickness direction and is electrically connected to other components; and conductive portions extending through the semiconductor chip body in the thickness direction to conduct electricity between the electrode portions that are opposite each other in the thickness direction. It should be noted that in a TSV-type semiconductor chip, a circuit forming surface may be formed only on one side, or a circuit forming surface may be formed on each of both sides.

[0064] Furthermore, as the semiconductor chip mentioned above, sensor chips that incorporate sensor elements (such as light-receiving elements or vibration elements) as components in the circuit can also be listed. Examples of sensor chips include CMOS (Complementary Metal-Oxide Semiconductor) chips and MEMS (Micro Electro-Mechanical Systems) chips.

[0065] As described above, a semiconductor chip in the form of TSV can, for example, be made by... Figure 3 The semiconductor wafer shown is obtained by cutting or other methods to serve as a connector for electronic devices. Figure 3 The semiconductor wafer 20 shown includes: a semiconductor wafer body 20a; electrode portions 20b and 20c, which are respectively disposed on two sides of the semiconductor wafer body 20a in the thickness direction and electrically connected to other components; and a conductive portion 20d, which penetrates the semiconductor wafer body 20a in the thickness direction and conducts the two electrode portions 20b and 20c to each other.

[0066] exist Figure 3 In one example of the semiconductor wafer 20 shown, the conductive portion 20d is made of a solid conductor. On the other hand, the conductive portion 20d may also be made of a hollow conductor, for example. That is, the conductive portion 20d only needs to be configured to electrically connect the two electrode portions 20b and 20c to each other.

[0067] In addition, Figure 3 In the semiconductor wafer 20 shown, in order to suppress conduction between adjacent electrode portions in the planar direction (specifically, between adjacent electrode portions 20b or between electrode portions 20c), an insulating layer 20e is formed on each of the two sides of the semiconductor wafer body 20a.

[0068] exist Figure 3 In the semiconductor wafer 20 shown, on one side, the outermost surface of the insulating layer 20e is flush with the outermost surface of each electrode portion 20b. Similarly, on the other side, the outermost surface of the insulating layer 20e is flush with the outermost surface of each electrode portion 20c. That is, in Figure 3 On each side of the semiconductor wafer 20 shown, the electrode portion 20b is arranged such that only the outermost surface is exposed.

[0069] On the other hand, on each of the two sides of the semiconductor wafer 20, each electrode portion 20b can also be arranged such that the entire surface is covered by an insulating layer 20e. That is, each electrode portion 20b can be embedded in the insulating layer 20e.

[0070] The two electrode portions 20b and 20c, and the conductive portion 20d, can be integrated or separate. For example, the electrode portions 20b and 20c, and the conductive portion 20d, are inserted into a through-hole (via) formed in a manner that penetrates the semiconductor wafer body 20a, for example, in an integrated state. Examples of materials constituting the electrode portions 20b and 20c, such as copper or aluminum, can be used. The thickness of the electrode portions 20b and 20c from the outermost surface of the semiconductor wafer body 20a can be 5 nm to 10 μm. The length of the conductive portion 20d can be approximately the same as the length of the through-hole (i.e., the thickness of the semiconductor wafer body 20a). The size and shape of the conductive portion 20d are appropriately selected based on the shape of the through-hole. For example, if the through-hole is cylindrical, a cylindrical shape with an outer diameter slightly smaller than the outer diameter of the through-hole is selected as the size and shape of the conductive portion 20d.

[0071] The insulating layer 20e is made of materials such as silicon dioxide (SiO2) or silicon nitride (SiN). The insulating layer 20e can be formed on both sides of the semiconductor wafer body 20a by methods such as CVD. The thickness of the insulating layer 20e is appropriately selected according to the thickness of the electrode portions 20b and 20c.

[0072] like Figure 4 As shown, the protective sheet 10 of this embodiment includes a protective layer 10a, and may further include a first release liner 10b overlapping one surface of the protective layer 10a. The protective sheet 10 may further include a second release liner 10c overlapping the other surface of the protective layer 10a (the surface opposite to the first surface). That is, the protective sheet 10 of this embodiment can be constructed by clamping the protective layer 10a from both sides using two release liners (the first release liner 10b and the second release liner 10c). In the case of the protective sheet 10 of this embodiment, the protective layer 10a is used to adhere to the protective surface of an electronic device having a protected surface or the protective surface of an electronic device connector obtained by connecting multiple said electronic devices.

[0073] The protective sheet 10 can be manufactured, for example, as follows. Specifically, a protective layer forming composition containing a solvent is applied to the first release liner 10b to a predetermined thickness (e.g., 40 μm) using an applicator. The solvent is evaporated by drying at a predetermined temperature for a predetermined time (e.g., 90 seconds at 115°C), forming a protective layer 10a on the first release liner 10b. Then, a second release liner 10c is overlapped onto the side opposite to the overlapping side of the first release liner 10b within the protective layer 10a.

[0074] Examples of compositions for forming the protective layer include those containing polyvinyl alcohol (PVA). These PVA-containing compositions can be obtained by suspending PVA in water to dissolve it.

[0075] It should be noted that, in Figure 4 In the example shown, the protective sheet 10 is formed by clamping it from both sides of the protective layer 10a with two release liner (first release liner 10b and second release liner 10c), but the configuration of the protective sheet 10 is not limited to this configuration. For example, the protective sheet 10 may consist only of the protective layer 10a, or the release liner may be overlapped only on one side of the protective layer 10a. That is, the protective sheet 10 only needs to have at least the protective layer 10a.

[0076] The protective layer 10a of the protective sheet 10 is preferably composed of a protective layer forming composition containing polyvinyl alcohol. As described above, the protective layer forming composition contains a solvent. The solvent is preferably water. When water is included as the solvent, the protective layer forming composition preferably contains 5 parts by mass and 80 parts by mass of polyvinyl alcohol relative to 100 parts by mass of water, more preferably 10 parts by mass and 70 parts by mass of polyvinyl alcohol, and even more preferably 15 parts by mass and 60 parts by mass of polyvinyl alcohol. In the protective layer forming composition, it is preferable that the polyvinyl alcohol is dissolved in a solvent (e.g., water). For example, the protective layer forming composition can be prepared by heating at a temperature of 20°C to 90°C to dissolve the polyvinyl alcohol dispersed in the solvent (e.g., water).

[0077] It should be noted that the temperature of the heat treatment is appropriately selected based on the degree of saponification of the polyvinyl alcohol. Specifically, polyvinyl alcohol with a low degree of saponification (e.g., a saponification degree of 45 or less) is difficult to dissolve in water at room temperature (25 ± 2 °C). In such cases, a higher treatment temperature is preferable. On the other hand, polyvinyl alcohol with a high degree of saponification (e.g., a saponification degree of 60 or more) is easily soluble in water at room temperature (25 ± 2 °C). In such cases, a lower treatment temperature is acceptable.

[0078] The viscosity of the above-mentioned protective layer forming composition at 25°C is preferably 0.03 Pa·s or more, more preferably 0.05 Pa·s or more, and even more preferably 0.1 MPa·s or more.

[0079] When the viscosity at 25°C is at or above the lower limit value as described above, unevenness in the thickness of the protective layer 10a can be suppressed when the above-described protective layer forming composition is applied to the release liner to form the protective layer 10a. The viscosity of the above-described protective layer forming composition at 25°C is preferably 15 Pa·s or less, more preferably 10 Pa·s or less, and even more preferably 5 Pa·s or less. By having the viscosity at 25°C at or below the upper limit value as described above, the coatability when applying the above-described protective layer forming composition to the release liner can be improved.

[0080] It should be noted that the viscosity of the above-mentioned protective layer forming composition at 25°C can be measured using a digital viscometer (product name "DV-IPrime") manufactured by Yinghong Precision Machinery Co., Ltd., using an LV-3 spindle at a rotation speed of 50 rpm.

[0081] The degree of saponification of the polyvinyl alcohol is preferably 45 or less, more preferably 35 or less, even more preferably 15 or less, even more preferably 12 or less, and particularly preferably 11 or less. The degree of saponification of the polyvinyl alcohol is preferably 1 or more, more preferably 2 or more, even more preferably 4 or more, even more preferably 6 or more, and particularly preferably 8 or more.

[0082] The degree of saponification is within the above-mentioned range, which makes polyvinyl alcohol less soluble in water at room temperature (25±2℃).

[0083] As described above, the temperature of the cooling water sprayed onto the cutting object, such as electronic component connectors, during blade cutting is typically below 25°C. Therefore, by forming a protective layer 10a from polyvinyl alcohol with a saponification degree within the aforementioned range, the protective layer 10a can be more adequately retained on the surface of the cutting object before blade cutting. Furthermore, as the water solubility of polyvinyl alcohol decreases, its lipophilicity may increase. Therefore, polyvinyl alcohol with a saponification degree within the aforementioned range may have higher lipophilicity. Therefore, by forming a protective layer 10a from polyvinyl alcohol with a saponification degree within the aforementioned range, the protective layer 10a can be more easily peeled off from the surface of the cutting object after blade cutting.

[0084] The degree of saponification of the polyvinyl alcohol can be determined by proton nuclear magnetic resonance spectroscopy. 1 The degree of saponification of polyvinyl alcohol (PVA) is determined by ¹H-NMR. It should be noted that if the sample contains additives, or if peaks originating from the additives overlap with peaks used for calculating the degree of saponification, the additives should be separated and removed by methanol extraction or similar treatment before determining the degree of saponification. The degree of saponification of PVA can be determined under the following conditions.

[0085] <Measurement Conditions>

[0086] • Analytical apparatus: FT-NMR: Bruker Biospin, AVANCE III-400.

[0087] • Observation frequency 400MHz (1H).

[0088] • Determine the solvent: heavy water or deuterated dimethyl sulfoxide (deuterated DMSO).

[0089] • The measured temperature is 80℃.

[0090] • External standard for chemical shift reference: TSP-d4 (0.00 ppm) (for heavy water determination);

[0091] The solvent used for determination (2.50 ppm) was deuterated DMSO.

[0092] The degree of saponification of the polyvinyl alcohol is calculated using the peak intensity of the methylene group derived from the vinyl alcohol unit (VOH) (heavy water; 2.0–1.0 ppm, deuterated DMSO; 1.9–1.0 ppm) and the peak intensity of the acetyl group derived from the vinyl acetate unit (VAc) (heavy water; around 2.1 ppm, deuterated DMSO; around 2.0 ppm), based on the following formula. In the formula, [VOH(-CH2)-] represents the peak intensity of the -CH2- derived from the vinyl alcohol unit. [VAc(CH3CO-)] represents the peak intensity of the CH3CO- derived from the vinyl acetate unit.

[0093] [Formula 1]

[0094]

[0095] The average degree of polymerization of the polyvinyl alcohol is preferably 100 or more, more preferably 150 or more, even more preferably 200 or more, and even more preferably 250 or more. The average degree of polymerization of the polyvinyl alcohol is preferably 3000 or less, more preferably 2000 or less, even more preferably 1000 or less, even more preferably 700 or less, particularly preferably 400 or less, and most preferably 300 or less.

[0096] The average degree of polymerization becomes greater, thus making polyvinyl alcohol less soluble in water at room temperature (25±2°C). As mentioned above, the hydrophilicity of such polyvinyl alcohol decreases, resulting in, arguably, increased lipophilicity. Therefore, by forming the protective layer 10a from polyvinyl alcohol with a higher average degree of polymerization, the protective layer 10a can be more adequately retained on the surface of the object being cut beforehand during blade cutting.

[0097] Furthermore, by forming the protective layer 10a from polyvinyl alcohol with a lower average degree of polymerization, the protective layer 10a can be more easily peeled off from the surface of the object being cut after the blade has cut.

[0098] The average degree of polymerization of the polyvinyl alcohol can be determined by aqueous GPC under the following conditions.

[0099] <Measurement Conditions>

[0100] • Analysis device: Agilent 1260 Infinity.

[0101] • Chromatographic columns TSKgel G6000PWXL (manufactured by TOSOH) and TSKgel G3000PWXL (manufactured by TOSOH);

[0102] Connect the two chromatographic columns in series.

[0103] • Column temperature: 40℃.

[0104] • Eluent: 0.2M sodium nitrate aqueous solution.

[0105] • Injection volume: 100 μL.

[0106] • Detector: Differential refractometer (RI).

[0107] • Standard samples: PEG standard sample and PVA standard sample.

[0108] The specific measurements were conducted as follows.

[0109] (1) The mass-average molecular weight (Mw) of the tested sample (PVA) and the PVA standard sample was calculated by GPC determination using PEG standard samples. It should be noted that the average degree of polymerization of the PVA standard sample was known.

[0110] (2) Use the average degree of polymerization of PVA standard samples and the calculated mass-average molecular weight Mw of PVA standard samples to make a calibration curve.

[0111] (3) Using the calibration curve, the average degree of polymerization of the tested sample (PVA) is determined based on the mass-average molecular weight Mw of the tested sample (PVA).

[0112] As the polyvinyl alcohol, multiple polyvinyl alcohols with different degrees of saponification can be used in combination, or multiple polyvinyl alcohols with different average degrees of polymerization can be used in combination.

[0113] The polyvinyl alcohol preferably does not have an oxanediol as shown in formula (1) at the end of the side chain or the main chain of the molecule.

[0114] When the protective layer 10a is formed from a composition for forming a protective layer containing polyvinyl alcohol, if the polyvinyl alcohol has the alkylene oxide, the steric hindrance caused by the alkylene oxide becomes a cause, and the water resistance of the protective layer 10a may decrease. Therefore, by ensuring that the polyvinyl alcohol does not have an alkylene oxide in its molecule, the steric hindrance caused by the alkylene oxide is eliminated, and thus the protective layer 10a can more adequately possess water resistance.

[0115]

[0116] The protective layer 10a of the protective sheet 10 may also contain organic compounds other than polyvinyl alcohol. Examples of organic compounds other than polyvinyl alcohol include polyvinyl butyral (PVB) and acrylic polymers.

[0117] Various known acrylic polymers can be used as the acrylic polymer. Such acrylic polymers preferably have carboxyl groups. Examples of acrylic polymers with carboxyl groups include, for instance, ARUFON UC-3150 manufactured by Toa Synthetic Co., Ltd.

[0118] When polyvinyl butyral is used as an organic compound other than polyvinyl alcohol, an organic solvent is preferably used as the solvent for suspending and dissolving the polyvinyl butyral. Examples of such organic solvents include alcohols such as ethanol, isopropanol (IPA), or butanol.

[0119] Furthermore, when using the acrylic polymer as an organic compound other than polyvinyl alcohol, an organic solvent is preferably used as the solvent for suspending and dissolving the acrylic polymer. Examples of such organic solvents include ethanol, isopropanol (IPA), methyl ethyl ketone (MEK), or acetone.

[0120] In addition to polyvinyl alcohol, polymers containing betaine units in their molecules (betaine polymers) can also be listed as organic compounds. Betaine polymers are polymers that have both cationic and anionic groups in their side chains. The mass-average molecular weight (Mw) of betaine polymers is preferably 50,000 or more, more preferably 800,000 or more.

[0121] The betaine polymer can also be suspended and dissolved in alcohols such as ethanol, isopropanol (IPA), or butanol. The mass-average molecular weight (Mw) of the betaine polymer can be calculated in the same way as the mass-average molecular weight (Mw) of polyvinyl alcohol described above.

[0122] Examples of betaine polymers include (methacryloyl ethyl betaine / acrylate) copolymers. Commercially available (methacryloyl ethyl betaine / acrylate) copolymers include the RAM RESIN series manufactured by Osaka Organic Chemicals Co., Ltd. It should be noted that the RAM RESIN series is a substance obtained by dissolving a betaine polymer in ethanol to a solid content concentration of 30% by mass.

[0123] The mass reduction rate W of the protective layer 10a after immersion in water at 25°C for 180 seconds relative to the mass of the protective layer 10a before immersion in water at 25°C. W The mass reduction rate can be 1% or more by mass, 3% or more by mass, 5% or more by mass, or 10% or more by mass. The mass reduction rate W W It can be less than 25% by mass, less than 20% by mass, or less than 15% by mass.

[0124] The mass reduction rate W of the protective layer 10a after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds relative to the mass of the protective layer 10a before immersion in the aqueous alcohol solution at 25°C. S It can be 45% or more by mass, or 60% or more by mass, or 80% or more by mass.

[0125] Naturally, the mass reduction rate W W The closer to 0% mass, the less soluble the 10a protective layer becomes in water. Mass reduction rate W S The closer the mass reduction rate is to 100%, the more readily the protective layer 10a dissolves in organic solvents such as alcohols. From this perspective, the mass reduction rate W... W Ideally, the mass percentage should be close to 0%, while the mass reduction rate W should be... S Ideally close to 100% by mass.

[0126] The thickness of the protective layer 10a is preferably 2 μm or more and 70 μm or less, more preferably 3 μm or more and 50 μm or less, and even more preferably 5 μm or more and 40 μm or less. The thickness of the protective layer 10a can be determined, for example, by measuring the thickness at any five randomly selected points using a dial indicator (PEACOCK, model R-205) and then taking the arithmetic mean of their thicknesses.

[0127] As the first release liner 10b, an example is a release liner obtained by performing a release treatment on a substrate sheet made of a resin such as polyethylene terephthalate (PET). As a release treatment, an example is a silicone release treatment. As such a release liner, for example, is the product name MRA50 manufactured by MITSUBISHI CHEMICAL. The second release liner 10c may also use the same release liner as the first release liner 10b.

[0128] The thicknesses of the first release liner 10b and the second release liner 10c are each preferably 15 μm or more and 75 μm or less, more preferably 20 μm or more and 60 μm or less. The thicknesses of the first release liner 10b and the second release liner 10c may be the same or different. The thicknesses of the first release liner 10b and the second release liner 10c can be determined in the same way as the thickness of the protective layer 10a.

[0129] Manufacturing methods for electronic devices

[0130] Next, a method for manufacturing electronic devices using the protective sheet 10 of this embodiment will be described.

[0131] The method for manufacturing an electronic device according to this embodiment is as follows: using a protective sheet having a protective layer having at least a portion of the surface to be attached to an electronic device connector, an electronic device is manufactured from the electronic device connector having the protective layer attached.

[0132] The method for manufacturing an electronic device according to this embodiment includes the following steps: for an electronic device connector obtained by connecting multiple electronic devices having a protected surface in such a way that the protected surfaces face in the same direction, a protective layer is attached to protect the protected surfaces of the multiple electronic devices; the electronic device connector with the protective layer attached is divided while being washed with water to obtain multiple electronic devices with the divided protective layers attached; and the divided protective sheets are removed from each protected surface of the multiple electronic devices.

[0133] In the manufacturing method of the electronic device according to this embodiment, the mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds is... W The content is 0% by mass or more and 30% by mass or less. Furthermore, the mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds is... S It is 40% or more by mass and less than 100% by mass.

[0134] In the manufacturing method of the electronic device according to this embodiment, when removing the segmented protective sheet, at least a portion of the protective layer is dissolved by contacting the segmented protective layer with a solution containing an organic solvent at a concentration of 55% by mass or more, thereby removing the segmented protective sheet from the plurality of electronic devices.

[0135] Furthermore, in the manufacturing method of the electronic device in this embodiment, the electronic device connector may be a semiconductor wafer obtained by connecting multiple semiconductor chips in such a way that the protected object faces the same direction.

[0136] It should be noted that, alternatively, multiple semiconductor chips can be connected in such a way that the protected object faces the same direction and is arranged on the same plane to form a semiconductor wafer.

[0137] Furthermore, in the case where the electronic device connector is the semiconductor wafer, the manufacturing method of the electronic device in this embodiment may include the following steps to reduce the thickness of the semiconductor wafer: while cooling with water, grinding the semiconductor wafer on the side that is not attached to the protective sheet.

[0138] Furthermore, in the case where the electronic device connector is the semiconductor wafer, in the manufacturing method of the electronic device in this embodiment, the semiconductor wafer may be ground before the plurality of semiconductor chips with the divided protective sheet attached are obtained.

[0139] It should be noted that, as mentioned above, grinding the semiconductor wafer from the side that is not attached to the protective film is usually called backside grinding.

[0140] The following is an example of a method for manufacturing electronic devices, using methods such as... Figure 3 The semiconductor wafer in TSV form shown and such Figure 4 The method of manufacturing a semiconductor chip in the form of a TSV using the protective sheet 10 shown in this embodiment will be described.

[0141] It should be noted that a TSV-type semiconductor wafer is equivalent to an electronic device connector, and a TSV-type semiconductor chip is equivalent to an electronic device. Furthermore, in the methods of manufacturing electronic devices, "cutting and monolithization" is a concept included within "segmentation."

[0142] A method for manufacturing a TSV-type semiconductor chip includes the following steps: attaching a protective sheet 10 to at least one circuit forming surface of a TSV-type semiconductor wafer, the TSV-type semiconductor wafer having a semiconductor wafer body and electrode portions disposed on both sides of the semiconductor wafer body and electrically connected to electrode portions of other components, and forming a circuit forming surface on at least one surface side of the semiconductor wafer (attaching the protective sheet S1); dividing the semiconductor wafer (more specifically, the semiconductor wafer body) with the protective sheet 10 attached by water rinsing to obtain a plurality of TSV-type semiconductor chips with the divided protective sheet 10 attached (dividing the semiconductor wafer S2); and removing the divided protective sheet 10 from the plurality of TSV-type semiconductor chips (removing the protective sheet S3).

[0143] The following is about the use of, for example Figure 5A The method for manufacturing a semiconductor chip in the form of a TSV using a blade cutting apparatus 300 equipped with a stage ST, a liquid ejection section SP, and a cutting blade DB will be described in further detail.

[0144] <Protective Sheet Adhesion S1>

[0145] In methods for manufacturing semiconductor chips in the form of TSVs, such as Figure 5A As shown, a TSV-type semiconductor wafer 20 is placed on the stage ST of the blade cutting apparatus 300 with the circuit formation surface exposed. Next, a protective layer 10a of a protective sheet 10 is attached to the semiconductor wafer 20, covering the circuit formation surface. Specifically, a first release liner 10b is peeled off from the protective sheet 10, exposing one surface of the protective layer 10a. Further, after attaching this exposed surface to the surface of the semiconductor wafer 20 (the surface where the electrode portion 20b is exposed), a second release liner 10c is peeled off. Thus, the protective sheet 10 is attached to the semiconductor wafer 20 with one side of the protective layer 10a exposed.

[0146] It should be noted that after the protective layer 10a of the protective sheet is attached to the semiconductor wafer as described above, the semiconductor wafer can be ground S1' on the side that is not attached to the protective sheet 10.

[0147] In the grinding S1' of semiconductor wafers, such as Figure 6A As shown, grinding (backside grinding) is performed using a grinding pad P until the semiconductor wafer 20 reaches a specified thickness. Through this grinding process, the thickness of the semiconductor wafer 20 is reduced to a specified thickness (see reference). Figure 6BIn terms of grinding, in order to cool the frictional heat generated by the grinding pad P during grinding, the grinding process is performed while cooling the semiconductor wafer 20 with water as described above (for example, spraying cooling water onto the semiconductor wafer 20, which is the object to be ground).

[0148] The manufacturing method of the electronic device in this embodiment is implemented using a protective layer 10a having the characteristics described above. Therefore, even when the semiconductor wafer 20 is being polished while being sprayed with cooling water, the protective layer 10a can be prevented from peeling off from the semiconductor wafer 20. That is, the protective sheet 10 in this embodiment can also be used as a back-side polishing belt.

[0149] It should be noted that in TSV-type semiconductor wafers, multiple electrode portions 20b and 20c are arranged on each of the two sides, therefore, grinding S1' of the semiconductor wafer is usually not performed. Grinding S1' of the semiconductor wafer is performed, for example, on the side of the semiconductor wafer where no circuit formation is formed.

[0150] <Semiconductor wafer dicing S2>

[0151] Next, as Figure 5B As shown, in the blade cutting apparatus 300, cooling water is sprayed from the liquid ejection section SP to water-wash the laminate of semiconductor wafer 20 and protective layer 10a, while the laminate is divided by the cutting blade DB, with at least a pair of electrode sections 20b and 20c facing each other in the thickness direction. Specifically, along... Figure 5A The cutting line "L" shown indicates that the semiconductor wafer 20 is cut into single-piece form by the cutting blade DB. It should be noted that... Figure 5B In the example shown, the semiconductor wafer 20 is divided in a manner that does not cut through the electrode portions 20b and 20c mentioned above. This results in a stack of multiple semiconductor chips 20' and the divided protective layer 10a. That is, by using the cutting blade DB, not only the semiconductor wafer 20 but also the protective layer 10a is divided into portions corresponding to the chip size.

[0152] As described above, in the protective sheet 10 of this embodiment, the mass reduction rate W of the protective layer 10a after immersion in water at 25°C for 180 seconds is... W The content is 0% or more and 30% or less by mass. Therefore, the protective layer 10a has the property of being difficult to dissolve in water. Therefore, as described above, even when cooling water is sprayed onto the protective layer 10a during blade cutting while it is attached to the surface of the semiconductor wafer 20, the protective layer 10a is sufficiently retained on the surface of the semiconductor wafer 20, which is the object to be cut.

[0153] <Removal of Protective Film S3>

[0154] Next, as Figure 5C As shown, in the blade cutting apparatus 300, a solution containing an organic solvent at a concentration of 55% by mass or more is sprayed from the liquid ejection section SP, causing at least a portion of the protective layer 10a to dissolve. This removes portions of the protective layer 10a, divided into chip-sized sections, from the surface of the plurality of semiconductor chips 20'. It should be noted that the temperature of the solution containing the organic solvent is, for example, below 25°C.

[0155] As the organic solvent, various known organic solvents such as methanol, ethanol, n-propanol, isopropanol, acetone, methyl ethyl ketone, diethyl ether, ethyl acetate, toluene, or n-hexane can be used. Among these, ethanol is preferred from the viewpoint of ease of acquisition and low toxicity.

[0156] A solution containing an organic solvent may contain the organic solvent at a concentration of 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. A solution containing an organic solvent may also contain the organic solvent at a concentration of 100% by mass. That is, a solution containing an organic solvent may be the organic solvent itself.

[0157] It should be noted that, from the viewpoint of reducing environmental impact, using a solution containing organic solvents at a concentration of 100% by mass is not necessarily preferred. From the viewpoint of reducing environmental impact, solutions containing organic solvents preferably contain organic solvents at a concentration of 50% by mass or more and 80% by mass or less.

[0158] As described above, in the protective sheet 10 of this embodiment, the mass reduction rate W of the protective layer 10a after immersion in an aqueous alcohol solution with a concentration of 55% by mass at 25°C for 180 seconds is... S The content is 40% by mass or more and 100% by mass or less. Therefore, the protective layer 10a has a certain degree of lipophilicity and is readily soluble in organic solvents. Therefore, as described above, when a solution containing an organic solvent is sprayed onto the surface of the protective layer 10a, which is attached to the surface of the plurality of semiconductor chips 20' in the divided state after cutting with a blade, the divided protective layer 10a can be easily peeled off from the plurality of semiconductor chips 20'.

[0159] The matters disclosed in this specification include the following. (1)

[0161] A protective sheet comprising a protective layer, the protective layer being adhered to the protective surface of an electronic device having a protected surface, or to the protective surface of an electronic device connector formed by connecting multiple electronic devices, wherein the mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds is... W The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds, where the mass is more than 0% by mass and less than 30% by mass. S It is 40% or more by mass and less than 100% by mass.

[0162] According to the protective sheet with this structure, a protective sheet that can provide sufficient retention of the object being cut during blade cutting and can be easily peeled off from the object being cut after the blade has cut is provided. (2)

[0164] According to the protective sheet described in (1) above, the protective layer is formed by a protective layer forming composition containing polyvinyl alcohol, wherein the degree of saponification of the polyvinyl alcohol is 45 or less and the average degree of polymerization is 100 or more and 3000 or less. (3)

[0166] A method for manufacturing an electronic device includes using a protective sheet having a protective layer on at least a portion of the surface of an electronic device connector to be bonded, and manufacturing an electronic device from the electronic device connector with the protective layer bonded thereon. The method comprises the following steps: bonding the protective layer to an electronic device connector obtained by connecting multiple electronic devices having protected surfaces in the same direction, such that the protected surfaces face the same direction; dividing the electronic device connector with the protective layer bonded thereon while washing it with water, to obtain multiple electronic devices with multiple divided protective layers bonded thereon; and removing the divided protective sheet from each protected surface of the multiple electronic devices, and immersing the protective layer in water at 25°C for 180 seconds, resulting in a mass reduction rate W of the protective layer. W The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with an alcohol concentration of 55% by mass at 25°C for 180 seconds, where the mass is more than 0% by mass and less than 30% by mass. S The content of the protective layer is 40% or more and 100% or less. When removing the segmented protective layer, at least a portion of the protective layer is dissolved by contacting the segmented protective layer with a solution containing an organic solvent at a concentration of 55% or more, thereby removing the segmented protective layer from the plurality of electronic devices. (4)

[0168] According to the manufacturing method of the electronic device described in (3) above, wherein the electronic device connector is a semiconductor wafer obtained by connecting multiple semiconductor chips in such a way that the protective object faces in the same direction, the manufacturing method of the electronic device further includes the following steps to reduce the thickness of the semiconductor wafer: while cooling with water, grinding the semiconductor wafer on the side that has not been attached to the protective sheet, and grinding the semiconductor wafer before obtaining the multiple semiconductor chips with the multiple protective layers after division attached as the multiple electronic devices. (5)

[0170] According to the manufacturing method of the electronic device described in (3) or (4) above, the protective layer is formed from a water-soluble resin composition containing polyvinyl alcohol, wherein the degree of saponification of the polyvinyl alcohol is 45 or less and the average degree of polymerization is 100 or more and 3000 or less.

[0171] It should be noted that the manufacturing method of the protective sheet and electronic device of the present invention is not limited to the described embodiments. Furthermore, the manufacturing method of the protective sheet and electronic device of the present invention is not limited by the described effects. Various modifications can be made to the manufacturing method of the protective sheet and electronic device of the present invention without departing from the spirit of the present invention.

[0172] In the above embodiments, the protective sheet 10 has been described in detail (see reference). Figure 4 The protective sheet 10 comprises: a protective layer 10a; a first release liner 10b, overlapping one surface of the protective layer 10a; and a second release liner 10c, on the other surface of the protective layer 10a (the side opposite to the first surface).

[0173] However, the structure of the protective sheet of the present invention is not limited thereto. For example, the protective sheet 10 can be as follows: Figure 7 The protective sheet is configured as shown. Specifically, the protective sheet 10 may also have a back-side polishing belt BG, which serves as a laminate of the adhesive layer 10d and the substrate 10e, instead of the second release liner 10c. That is, the protective sheet 10 can be configured by sequentially laminating the first release liner 10b, the protective layer 10a, the adhesive layer 10d, and the substrate 10e. By configuring the protective sheet 10 in this way, a back-side polishing process for reducing the thickness of the electronic device connector can be performed after the exposed surface of the protective layer 10a, which is exposed after the first release liner 10b is peeled off, is bonded to an electronic device connector such as a semiconductor wafer.

[0174] It should be noted that, from the viewpoint of preventing the electronic device connector from peeling off from the protective layer 10a during the back-side grinding process, it is preferable that the protective layer 10a has sufficient adhesion to the electronic device connector. For example, by having a high storage modulus (e.g., 0.1 MPa or more) at room temperature (23 ± 2 °C), the protective layer 10a can have sufficient adhesion to the electronic device connector. Furthermore, by having a low viscosity of the protective layer 10a at the temperature when it is bonded to the electronic device connector (e.g., 40 °C), the following properties of the protective layer 10a to the electronic device connector can be improved. Thus, the protective layer 10a can have sufficient adhesion to the electronic device connector.

[0175] Furthermore, the surface energy difference between the surface of the protective layer 10a that is in contact with the electronic device connector and the surface energy of the electronic device connector that is in contact with the protective layer 10a is 25 mJ / m. 2 Above and 85mJ / m 2 Therefore, the protective layer 10a can provide sufficient sealing for the electronic device connector.

[0176] In the above embodiments, the following example is described: In the semiconductor wafer 20, on any side surface, the outermost surface of the insulating layer 20e is flush with the outermost surface of each electrode portion.

[0177] However, the arrangement of the electrode portions 20b and 20c in the semiconductor wafer 20 is not limited to this. For example, in the semiconductor wafer 20, the surface portion of each electrode portion may protrude from the outermost surface of the insulating layer 20e. Furthermore, the electrode portions 20b and 20c may also be formed from solder balls.

[0178] In the above embodiments, as a method for manufacturing electronic devices, an example of obtaining multiple semiconductor chips as electronic devices by using a semiconductor wafer in the form of a TSV as an electronic device connector has been described.

[0179] However, the method for manufacturing the electronic device of the present invention is not limited thereto. For example, the method for manufacturing the electronic device of the present invention can be applied to situations where, for example, using... Figure 1 The wafer-level package 100 shown serves as an electronic device connector, thereby obtaining a plurality of semiconductor packages 120 that function as electronic devices. Furthermore, the method for manufacturing electronic devices according to the present invention can also be applied to situations where, for example, Figure 2B The image sensor package shown uses a stacked body 200' as an electronic component connector to obtain multiple image sensor packages 200 as electronic components.

[0180] Example

[0181] Next, specific examples will be provided to further illustrate the present invention. The following examples are for further detailed explanation of the present invention and do not limit the scope of the invention.

[0182] [Example 1]

[0183] An aqueous dispersion solution was prepared in a container by dispersing polyvinyl alcohol (PVA, saponification degree 35, average degree of polymerization 380) in water.

[0184] Next, the container containing the aqueous dispersion solution was placed in a water bath at 90°C, and the polyvinyl alcohol was dissolved in the water by stirring the aqueous dispersion solution to obtain the protective layer forming composition of Example 1.

[0185] Next, the above-mentioned protective layer forming composition is applied to the release-treated surface of the first PET release liner (MRA50, 50 μm thickness, manufactured by MITSUBISHICHEMICAL) with a thickness of 40 μm using a coating machine.

[0186] Furthermore, a protective layer is formed on the first PET release liner by drying the first PET release liner coated with the protective layer forming composition at 115°C for 90 seconds.

[0187] Thus, the protective sheet of Example 1 was obtained.

[0188] The degree of saponification and the average degree of polymerization of polyvinyl alcohol were each determined according to the methods described in the above-described embodiments.

[0189] Furthermore, following the process described in the above-described embodiments, the mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds relative to the mass of the protective layer before immersion in water at 25°C is calculated. W .

[0190] Furthermore, following the process described in the above-described embodiment, the mass reduction rate W of the protective layer after immersion in an alcohol-water solution with a 55% by mass alcohol concentration at 25°C for 180 seconds relative to the mass of the protective layer before immersion in the alcohol-water solution at 25°C is calculated. S .

[0191] Furthermore, following the process described in the above embodiments, the mass reduction rate W of the protective layer after immersion in an alcohol-water solution with a 20% by mass alcohol concentration at 25°C for 180 seconds relative to the mass of the protective layer before immersion in the alcohol-water solution at 25°C is calculated. S’ Ethanol (EtOH) is used as the alcohol.

[0192] The results of the saponification degree and average degree of polymerization measurements, along with the calculated mass reduction rate W, were used to determine the saponification degree and average degree of polymerization. W Weight reduction rate W S and quality reduction rate W S’ The results are shown in Table 1.

[0193] [Example 2]

[0194] Polyvinyl alcohol with a saponification degree of 10 and an average degree of polymerization of 250 was used. Otherwise, the protective sheet of Example 2 was obtained in the same manner as in Example 1.

[0195] The degree of saponification and the average degree of polymerization of polyvinyl alcohol were determined in the same manner as in Example 1. Furthermore, the mass reduction rate W was determined in the same manner as in Example 1. W Weight reduction rate W S and the rate of quality reduction W S’ .

[0196] The results of the saponification degree and average degree of polymerization measurements, along with the calculated mass reduction rate W, were used to determine the saponification degree and average degree of polymerization. W Weight reduction rate W S and quality reduction rate W S’ The results are shown in Table 1.

[0197] [Example 3]

[0198] Polyvinyl alcohol with a saponification degree of 5 and an average degree of polymerization of 200 was used. Otherwise, the protective sheet of Example 3 was obtained in the same manner as in Example 1.

[0199] The degree of saponification and the average degree of polymerization of polyvinyl alcohol were determined in the same manner as in Example 1.

[0200] Furthermore, the mass reduction rate W was calculated in the same manner as in Example 1. W Weight reduction rate W S and the rate of quality reduction W S’ .

[0201] The results of the saponification degree and average degree of polymerization measurements, along with the calculated mass reduction rate W, were used to determine the saponification degree and average degree of polymerization. W Weight reduction rate W S and quality reduction rate W S’ The results are shown in Table 1.

[0202] [Example 4]

[0203] Polyvinyl alcohol with a saponification degree of 22 and an average degree of polymerization of 2000 was used. Otherwise, the protective sheet of Example 4 was obtained in the same manner as in Example 1.

[0204] The degree of saponification and the average degree of polymerization of polyvinyl alcohol were determined in the same manner as in Example 1.

[0205] Furthermore, the mass reduction rate W was calculated in the same manner as in Example 1. W Weight reduction rate W S and the rate of quality reduction W S’ .

[0206] The results of the saponification degree and average degree of polymerization measurements, along with the calculated mass reduction rate W, were used to determine the saponification degree and average degree of polymerization. W Weight reduction rate W S and quality reduction rate W S’ The results are shown in Table 1.

[0207] [Example 5]

[0208] As a composition for forming a protective layer, a substance obtained by dissolving a betaine polymer in ethanol (hereinafter also referred to as a composition containing a betaine polymer) was used instead of a substance obtained by dissolving polyvinyl alcohol in water. Otherwise, the protective sheet of Example 5 was obtained in the same manner as in Example 1.

[0209] Then, the mass reduction rate W was calculated in the same manner as in Example 1. W Weight reduction rate W S and the rate of quality reduction W S’ .

[0210] The mass reduction rate W will be calculated. W Weight reduction rate W S and the rate of quality reduction W S’ The results are shown in Table 1.

[0211] It should be noted that the composition containing betaine polymer is "RAM RESIN-1000" manufactured by Osaka Organic Chemicals Co., Ltd. (solid content concentration: 30% by mass, mass-average molecular weight Mw: about 80,000, glass transition temperature Tg: 60°C).

[0212] [Comparative Example 1]

[0213] Polyvinyl alcohol with a saponification degree of 65 and an average degree of polymerization of 240 was used. Otherwise, the protective sheet of Comparative Example 1 was obtained in the same manner as in Example 1.

[0214] The degree of saponification and the average degree of polymerization of polyvinyl alcohol were determined in the same manner as in Example 1.

[0215] Furthermore, the mass reduction rate W was calculated in the same manner as in Example 1. W and quality reduction rate W S .

[0216] The results of the saponification degree and average degree of polymerization were used to calculate the mass reduction rate W. W and quality reduction rate W S The results are shown in Table 1.

[0217] <Water Resistance>

[0218] After attaching a protective layer of a protective sheet with the same planar dimensions as the bare wafer to one surface of the bare wafer (12 inches (300 mm) outer diameter, 200 μm thickness), the first PET release liner is peeled off from the protective layer to create a laminate of the bare wafer and the protective layer, which is the object to be cut.

[0219] Then, cutting was performed using a blade cutting device (DISCO cutting machine, model "DFD6361") equipped with a stage, a liquid ejection section, and a cutting blade, under the following conditions. Specifically, when cutting the laminate into multiple small pieces (bare chips) with a planar size of 10mm × 10mm, the degree of peeling of the protective layer of each example of the protective sheet was evaluated for any 10 bare chips located in the center portion of the bare wafer.

[0220] Cutting conditions

[0221] • Single cut.

[0222] Blade: ZH05 SD-3000-N1-70CC.

[0223] • Blade rotation speed: 45000rpm.

[0224] • Blade travel speed: 50 mm·sec.

[0225] • Water flow rate: 0.5 mL / min.

[0226] • Water temperature: 23℃.

[0227] Thus, for a stack of bare chips and protective layers of diced protective wafers, the degree to which the diced protective layer is peeled off from the bare chip is evaluated.

[0228] It should be noted that the laminate of the bare wafer and the protective layer of the protective wafer is arranged on the stage of the blade cutting device with the protective wafer side as the cutting start surface. That is, during cutting using the blade cutting device, water is sprayed onto the protective layer of the protective wafer.

[0229] Furthermore, the laminate of the bare wafer and the protective layer of the protective film is disposed on the stage with the bare wafer attached to the dicing tape. Specifically, after the adhesive layer of the dicing tape, which includes a substrate and an adhesive layer laminated on the substrate, is attached to the laminate, the exposed side of the dicing tape is disposed on the stage.

[0230] The degree of protective layer peeling in each example was evaluated using a digital microscope (Keyence, model "VHX-6000") at 30x magnification. The degree of peeling of the separated protective layer from the bare die was then evaluated according to the following evaluation criteria.

[0231] Evaluation criteria

[0232] • Advantage: Regarding the portion of the protective layer that has been peeled off after segmentation, the average distance (average of 10 pieces) from the edge of the bare chip to the unpeeled portion is less than 500 μm.

[0233] • Good: For the portion of the protective layer that has been peeled off after segmentation, the average distance (average of 10 pieces) from the edge of the bare chip to the unpeeled portion is greater than 500μm and less than 1mm.

[0234] • Non-compliant: For the portion of the protective layer that has been peeled off after splitting, the average distance (average of 10 pieces) from the edge of the bare chip to the unpeeled portion is greater than 1 mm.

[0235] For each example of the protective sheet, the results of evaluating the water resistance of the protective layer are shown in Table 1.

[0236] <Removal>

[0237] As described above, the laminate of the bare wafer and the protective layer of the protective sheet in each example is cut into multiple small pieces with a planar size of 10mm × 10mm (the laminate obtained by stacking the bare wafer and the divided protective layer). Then, the dicing tape with multiple of the above-mentioned small pieces attached is removed from the stage.

[0238] Then, the dicing strip with multiple of the aforementioned small pieces attached is immersed in a running water bath containing an alcohol-water solution (ethanol-water solution) with an alcohol concentration of 55%. This removes the protective layer of the diced protective pieces from the surface of each bare die. The degree of protective layer removal is then evaluated for 10 randomly selected bare dies.

[0239] The degree of protective layer removability is evaluated according to the following criteria.

[0240] Evaluation criteria

[0241] • Excellent: After immersion for 60 seconds, no protective layer residue was visually detected on any surface of any of the 10 bare chips.

[0242] • Good: Although after immersion for 60 seconds, the level of protective layer residue that would be problematic in practical applications was visually confirmed on any surface of the 10 bare chips, after immersion for 300 seconds, no protective layer residue was visually confirmed on any surface of the 10 bare chips.

[0243] • Non-compliant: Even after immersion for 300 seconds, the level of protective layer residue that would be problematic in practical applications is still visually confirmed on any surface of any of the 10 bare chips.

[0244] For each example of the protective film, the results of evaluating the removability (55%) of the protective layer are shown in Table 1.

[0245] Furthermore, the removeability (20%) of the protective layer of each protective sheet was also evaluated using an aqueous solution of alcohol with a concentration of 20% (ethanol concentration). The results are also shown in Table 1.

[0246] [Table 1]

[0247] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Protective layer forming material PVA PVA PVA PVA Betaine polymer PVA Degree of saponification 35 10 5 22 - 65 Average degree of polymerization 380 250 200 2000 - 240 Mass reduction rate W W [Mass %]]] 16 11 16 4 3 100 Mass reduction rate W S′ [Mass %]]] 25 18 23 8 20 - Mass reduction rate W S [Mass %]]] 100 100 100 45 100 - Water resistance of protective layer Good Excellent Good Excellent Excellent Unqualified Removability of protective layer (55%) Excellent Excellent Excellent Good Excellent - Removability of protective layer (20%) Unqualified Unqualified Unqualified Unqualified Unqualified -

[0248] As shown in Table 1, in the protective sheets of each embodiment, the water resistance of the protective layer is rated as excellent or good, and the removability of the protective layer is also rated as excellent or good.

[0249] In contrast, in the protective sheet of Comparative Example 1, the water resistance of the protective layer was deemed unsatisfactory. Because the water resistance of the protective layer was deemed unsatisfactory, an evaluation of the removability of the protective layer could not be performed.

[0250] As can be seen from the results above, the mass reduction rate W W The mass percentage is 0% or more and 30% or less, and the mass reduction rate is W. S A protective layer of 40% to 100% by mass provides sufficient retention (adhesion) to the object being cut during blade cutting and can be easily peeled off from the object after cutting.

[0251] It should be noted that, according to the results in Table 1, the removal effect of the protective layer in an alcohol-water solution with a concentration of 20% by mass at 25°C was not fully realized.

[0252] Industrial availability

[0253] The protective sheet of the present invention is suitable, for example, as an auxiliary tool in the manufacture of electronic devices such as semiconductor chips. The manufacturing method of the electronic device of the present invention is suitable for use, for example, in the manufacture of electronic devices such as semiconductor chips.

[0254] Explanation of reference numerals in the attached figures

[0255] 10: Protective sheet; 10a: Protective layer; 10b: First release liner; 10c: Second release liner; 10d: Adhesive layer; 10e: Substrate; 20: Semiconductor wafer; 20a: Semiconductor wafer body; 20b: Electrode portion; 20c: Electrode portion; 20d: Conductive portion; 20e: Insulating layer; 20': Semiconductor chip; 100: Wafer-level package; 110: Circuit board; 120: Semiconductor package; 120a: Glass sheet; 200: Image sensor package; 210: Sensor chip body; 220: Adhesive layer; 230: Glass sheet; 200': Image sensor package laminate; 210': Sensor wafer body; 220': Adhesive layer; 230': Glass plate; 300: Blade cutting device; BG: Back grinding belt; DB: Cutting blade; SP: Liquid ejection portion; ST: Stage.

Claims

1. A protective sheet comprising a protective layer, the protective layer being adhered to the protective surface of an electronic device having a protected surface, or to the protective surface of an electronic device connector formed by connecting multiple said electronic devices. The mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds W It is between 0% and 30% by mass. The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with a concentration of 55% by mass at 25°C for 180 seconds. S It is 40% or more by mass and less than 100% by mass.

2. The protective sheet according to claim 1, wherein, The protective layer is formed from a protective layer forming composition containing polyvinyl alcohol. The polyvinyl alcohol has a saponification degree of 45 or less and an average degree of polymerization of 100 or more and 3000 or less.

3. A method for manufacturing an electronic device, comprising using a protective sheet having a protective layer having at least a portion of a protective layer to be attached to the surface of an electronic device connector, and manufacturing an electronic device from the electronic device connector having the protective layer attached thereto. The method for manufacturing the electronic device comprises the following steps: For an electronic device connector obtained by connecting multiple electronic devices with protected surfaces in such a way that the protected surfaces face the same direction, the protective layer is attached in a way that protects the protected surfaces of the multiple electronic devices. The electronic device connector with the protective layer attached is simultaneously washed with water and divided to obtain multiple electronic devices with multiple divided protective layers attached; and The segmented protective sheet is removed from each protected surface of the plurality of electronic devices. The mass reduction rate W of the protective layer after immersion in water at 25°C for 180 seconds W It is between 0% and 30% by mass. The mass reduction rate W of the protective layer after immersion in an aqueous alcohol solution with a concentration of 55% by mass at 25°C for 180 seconds. S It is 40% or more by mass and less than 100% by mass. When removing the segmented protective sheet, at least a portion of the protective layer is dissolved by contacting the segmented protective layer with a solution containing an organic solvent at a concentration of 55% by mass or more, thereby removing the segmented protective sheet from the plurality of electronic devices.

4. The method for manufacturing an electronic device according to claim 3, wherein, The electronic device connector is a semiconductor wafer obtained by connecting multiple semiconductor chips with the protected object facing the same direction. The manufacturing method of the electronic device further includes the following steps to reduce the thickness of the semiconductor wafer: while cooling with water, grinding the semiconductor wafer from the side that has not been attached to the protective sheet. Before the semiconductor chips, which are in a state with multiple protective layers attached after being divided, are used as the multiple electronic devices, grinding of the semiconductor wafers is performed.

5. The method for manufacturing the electronic device according to claim 3 or 4, wherein, The protective layer is formed of a water-soluble resin composition containing polyvinyl alcohol. The polyvinyl alcohol has a saponification degree of 45 or less and an average degree of polymerization of 100 or more and 3000 or less.

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