Protective film-forming film and method for manufacturing conductive workpiece with protective

Abstract

The invention provides a protective film forming film and a method for manufacturing a protective film-equipped workpiece singulation such as a protective film-equipped semiconductor chip by using the protective film forming film. The protective film forming film is capable of forming a protective film which can sufficiently dissipate heat generated on a workpiece singulation such as a semiconductor chip and which has sufficiently high adhesion reliability in an environment in which the temperature changes greatly. The protective-film-forming film is a curable protective-film-forming film containing a filler, and when a rectangular region having an area of 625 [mu] m2 and having a length as one side as the same as the thickness in the thickness direction is observed in a cross-section parallel to the thickness direction of the cured protective-film-forming film, the thickness of the rectangular region is greater than the thickness in the thickness direction. The ratio of the cross-sectional area of the filling material to the minimum area including the circle of all the outer peripheral lines of the cross-section of the filling material is 0.6-0.9, and the maximum length of the cross-section of the filling material is greater than 0.5 [mu] m. The amount of the filling material is 0.08-0.80 / [mu] m < 2 > or more and 0.80-0.80 / [mu] m < 2 > or less.

Description

Technical Field

[0001] The present invention relates to a protective film-forming film and a method for producing a workpiece singulated with a protective film. In particular, the present invention relates to a protective film-forming film capable of forming a protective film having excellent heat dissipation properties and bonding reliability, and a method for producing a workpiece singulated with a protective film, such as a semiconductor chip with a protective film, using the protective film-forming film. Background Art

[0002] Semiconductor chips are obtained in the form of workpiece singulations, which are obtained by singulating workpieces such as wafers with circuits formed thereon. In recent years, semiconductor devices have been manufactured using a mounting method known as flip-chip bonding, using semiconductor chips having circuit surfaces on which convex electrodes such as bumps are formed. In this mounting method, when mounting a semiconductor chip, the circuit surface side of the semiconductor chip is flipped (face down) toward the chip mounting portion and bonded. As a result, a structure is formed in which the back side of the semiconductor chip, where no circuit is formed, is exposed.

[0003] Therefore, to protect semiconductor chips from impacts during transport, a hard protective film made of an organic material is often formed on the back side of the semiconductor chip. This protective film is formed by, for example, applying a protective film-forming film to the back side of a semiconductor wafer and then curing it. The semiconductor chip with the protective film is then mounted on a substrate or the like as an electronic component.

[0004] As semiconductor chips become smaller and more powerful, the heat generated by semiconductor chips during operation also increases. If excessive heat is generated due to the heat generated by the semiconductor chip, it will cause failure or deformation of the semiconductor chip, and the reliability of the semiconductor chip will decrease. In order to eliminate the heat generated by the semiconductor chip, the protective film in contact with the semiconductor chip contains a filler (filling material) with thermal conductivity, so that the heat generated in the semiconductor chip is dissipated through the filler in the protective film. However, if the amount of filler in the protective film is large, there is a problem of reduced adhesion between the protective film and the semiconductor chip.

[0005] Patent Document 1 discloses a resin film forming layer containing nitride particles as an inorganic filler. Patent Document 1 discloses that the resin film forming layer can improve the adhesiveness to an adherend and the heat dissipation characteristics of a semiconductor device.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: International Publication No. 2014 / 083872 Summary of the Invention

[0009] (1) Technical issues to be resolved

[0010] However, Patent Document 1 has a problem in that the resin film cannot adapt to a wide range of temperature changes from the perspective of adhesion to an adherend, and the resin film has insufficient adhesion reliability in an environment with large temperature changes.

[0011] The present invention has been completed in view of the above situation, and its purpose is to provide a protective film forming film and a method for using the protective film forming film to manufacture a workpiece singulation object with a protective film, such as a semiconductor chip with a protective film, wherein the protective film forming film can form a protective film that can fully dissipate the heat generated on the workpiece singulation object such as the semiconductor chip, and has sufficiently high bonding reliability in an environment with large temperature changes.

[0012] (2) Technical solution

[0013] The scheme of the present invention is as follows.

[0014] [1] A protective film-forming film, which is a curable protective film-forming film containing a filler, wherein:

[0015] In a cross section parallel to the thickness direction of the protective film-forming film after curing, a length equal to the thickness in the thickness direction is observed as one side and the area is 625 μm. 2 In the case of a rectangular area, the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest circle containing all the outer circumferences of the cross-sectional area of ​​the filler is 0.6 or more and 0.9 or less, and the maximum length of the cross-sectional area of ​​the filler is greater than 0.5 μm, and the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest circle containing all the outer circumferences of the cross-sectional area of ​​the filler is 0.08 or more / μm. 2 and less than 0.80 / μm 2 exist.

[0016] [2] The protective film-forming film according to [1], wherein the protective film-forming film comprises a curable component and a polymer component.

[0017] [3] The protective film-forming film according to [1] or [2], wherein the average particle size of the filler is 0.8 μm or more and 5 μm or less.

[0018] [4] The protective film-forming film according to any one of [1] to [3], wherein the particle size distribution of the filler is a unimodal distribution.

[0019] [5] The protective film-forming film according to any one of [1] to [4], wherein the protective film-forming film has a thickness of less than 50 μm.

[0020] [6] The protective film-forming film according to any one of [1] to [5], wherein the filler is made of aluminum oxide.

[0021] [7] The protective film forming film according to any one of [1] to [6], wherein the ratio of the total area occupied by the cross section of the filling material in the rectangular region is 30% to 70% when the area of ​​the rectangular region is 100%.

[0022] [8] A method for manufacturing a single-piece workpiece with a protective film, comprising:

[0023] A step of attaching the protective film-forming film according to any one of [1] to [7] to a workpiece;

[0024] After the step of attaching the film to the workpiece, a step of curing the protective film-forming film; and

[0025] After the step of attaching the workpiece to the workpiece, the step of singulating the workpiece to which the protective film or protective film-forming film is attached is performed to obtain a plurality of singulated workpieces with the protective film or protective film-forming film.

[0026] (3) Beneficial effects

[0027] According to the present invention, a protective film forming film and a method for using the protective film forming film to manufacture a workpiece singulation object with a protective film, such as a semiconductor chip with a protective film, can be provided. The protective film forming film can form a protective film that can sufficiently dissipate the heat generated on the workpiece singulation object, such as the semiconductor chip, and has sufficiently high bonding reliability in an environment with large temperature changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A It is a schematic diagram for explaining the maximum length of the cross section of the filling material.

[0029] Figure 1B A schematic diagram for explaining the minimum circle containing all the outer circumferences of a cross section containing a filling material.

[0030] Figure 1C This is a schematic diagram showing an example of a cross section of a filling material in which the polyhedron is composed of planes.

[0031] Figure 1D A schematic diagram showing an example of a cross section of a filling material whose polyhedron is composed of curved surfaces.

[0032] Figure 2 A schematic diagram for explaining a method for determining a filler having a cross-sectional area of ​​0.6 to 0.9 relative to the area of ​​the smallest circle containing all outer circumferences of the cross section containing the filler and a maximum cross-sectional length of greater than 0.5 μm.

[0033] Figure 3 This is a schematic cross-sectional view of an example of the protective film forming sheet according to this embodiment.

[0034] Figure 4 This is a schematic cross-sectional view of an example of the composite sheet for forming a protective film according to this embodiment.

[0035] Figure 5A It is a schematic cross-sectional view for explaining the step of attaching the protective film forming sheet of this embodiment to a wafer.

[0036] Figure 5B It is a schematic cross-sectional view for explaining the step of attaching the composite sheet for forming a protective film according to the present embodiment to a wafer.

[0037] Figure 6 A schematic cross-sectional view for explaining the process of singulating a wafer with a protective film.

[0038] Description of Reference Numerals

[0039] 1: Protective film-forming film; 2: Protective film-forming film after curing (protective film); 3: Filler; 10: Protective film-forming sheet; 11: Protective film-forming composite sheet. DETAILED DESCRIPTION

[0040] Hereinafter, the present invention will be described in detail based on specific embodiments using the accompanying drawings.

[0041] First, main terms used in this specification are explained.

[0042] The workpiece refers to a plate-like object to which the protective film forming film of the present embodiment is attached and which is then singulated. The protective film forming film is attached to the back of the workpiece. As the workpiece, a circular wafer (including a case with an oriented plane), a polygonal strip (strip substrate) having panel-level packaging and molded resin sealing, etc. can be listed, wherein, from the perspective of being easy to obtain the effect of the present invention, a wafer composed of an inorganic material is preferably used. As a wafer, for example, it can be a semiconductor wafer such as a silicon wafer, a gallium arsenide wafer, a silicon carbide wafer, a gallium nitride wafer, an indium phosphide wafer, or an insulator wafer such as a glass wafer, a lithium tantalate wafer, a lithium niobate wafer, etc. In addition, it can also be a reconstructed wafer composed of a resin and a semiconductor used in the production of a fan-out package (Fan-Out Package), etc. From the perspective of being easy to obtain the effect of the present invention, as a wafer, a semiconductor wafer or an insulator wafer is preferably used, and a semiconductor wafer is more preferably used.

[0043] Workpiece singulation refers to the process of dividing the workpiece into individual pieces according to circuits. For example, when the workpiece is a wafer, the individual pieces are chips. When the workpiece is a strip (strip substrate) that has been subjected to panel-level packaging or molded resin sealing, the individual pieces are semiconductor packages.

[0044] The "front surface" of a workpiece refers to a surface on which circuits, electrodes, etc. are formed, and the "back surface" of a workpiece refers to a surface on which no circuits, etc. are formed. The electrodes may be convex electrodes such as bumps.

[0045] A "principal surface" refers to a surface that is larger than the other surfaces in a plate-like object. Typically, a plate-like object has two principal surfaces and side surfaces, with the two principal surfaces facing each other. In a workpiece, the "front" and "back" surfaces are principal surfaces.

[0046] “(Meth)acrylate” is used as a term representing both “acrylate” and “methacrylate”, and the same applies to other similar terms.

[0047] The "energy ray" refers to ultraviolet rays, electron beams, and the like, and is preferably ultraviolet rays.

[0048] Unless otherwise specified, the "weight average molecular weight" refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC). Measurements by this method are performed, for example, using a high-performance GPC apparatus "HLC-8120GPC" manufactured by TOSOH CORPORATION, in which high-performance columns "TSK guard column HXL-H," "TSK GelGM HXL," and "TSK Gel G2000 HXL" (all manufactured by TOSOH CORPORATION) are connected in this order, with a column temperature of 40°C and an injection rate of 1.0 ml / min, using a differential refractometer as the detector.

[0049] The release film is a film that supports the protective film-forming film in a releasable manner. The film is used without limitation in thickness and includes the concept of a sheet.

[0050] The mass ratios in the description of compositions such as the protective film-forming film composition are based on the active ingredients (solid content), and the solvent is not included unless otherwise specified.

[0051] (1. Protective film forming film)

[0052] The protective film forming film of this embodiment is used to form a protective film on the workpiece or workpiece singulation after being attached to the workpiece. After the protective film is formed, the workpiece with the protective film or the workpiece singulation with the protective film is obtained.

[0053] As described above, since singulated workpieces such as semiconductor chips generate a lot of heat during operation, the protective film in contact with the singulated workpieces is required not only to protect the singulated workpieces but also to quickly dissipate the heat generated in the singulated workpieces (heat dissipation).

[0054] The heat dissipation property of the protective film is generally achieved by including a large amount of a filler (filler) made of a material with high thermal conductivity in the protective film, thereby forming a heat conduction path (path).

[0055] However, if the protective film contains a large amount of filler, the amount of components responsible for adhesion to the workpiece individual particles becomes relatively small. As a result, the reliability of the adhesion between the workpiece individual particles and the protective film decreases. This is particularly problematic in harsh environments, such as those with large temperature fluctuations.

[0056] Therefore, in this embodiment, by using a protective film-forming film containing a specific filler material described later at a predetermined ratio, the cured protective film-forming film (protective film) can achieve both heat dissipation and adhesion reliability.

[0057] The protective film-forming film of this embodiment is curable. Therefore, the protective film is obtained as a cured product by curing the uncured protective film-forming film. Therefore, the cured protective film-forming film is different from the protective film-forming film. The cured protective film-forming film (protective film) imparts a predetermined function to the workpiece or workpiece individual particles.

[0058] After the curable protective film-forming film is superimposed on the workpiece, the protective film-forming film is cured, whereby the protective film can be firmly bonded to the workpiece, and a durable protective film can be formed.

[0059] Examples of the cured product include heat-cured products and energy-ray-cured products. That is, examples of the curable protective film-forming film include heat-curable protective film-forming films and energy-ray-curable protective film-forming films.

[0060] The protective film-forming film contains a filler (described below) and preferably further contains a colorant, etc., and therefore tends to have low light transmittance. Therefore, when the protective film-forming film is cured by irradiation with energy rays to obtain an energy-ray-cured product, particularly when the protective film-forming film is thick, energy-ray curing tends to be insufficient.

[0061] On the other hand, a thermosetting protective film-forming film can be fully cured by heating even when thick, making it easy to form a protective film that can fully exhibit the required properties. In addition, by using a conventional heating device such as a heating oven, multiple protective film-forming films can be heated together for thermal curing. Therefore, in this embodiment, the protective film-forming film is preferably thermosetting.

[0062] Whether a protective film-forming film is thermosetting can be determined as follows. First, a protective film-forming film at room temperature (23°C) is heated to a temperature higher than room temperature and then cooled to room temperature to produce a heated and cooled protective film-forming film. Next, the hardness of the heated and cooled protective film-forming film is compared with the hardness of the protective film-forming film before heating at the same temperature. If the heated and cooled protective film-forming film is harder, the protective film-forming film is determined to be thermosetting.

[0063] Furthermore, the protective film-forming film preferably has adhesiveness at room temperature (23°C) or develops adhesiveness by heating. This allows the workpiece to be bonded together when it is superimposed on the protective film-forming film. This allows for reliable positioning before the protective film-forming film is cured.

[0064] The protective film-forming film may be composed of a single layer or two or more layers. When the protective film-forming film has multiple layers, these multiple layers may be the same or different from each other, and the combination of the layers constituting these multiple layers is not particularly limited.

[0065] In this embodiment, the protective film forming film is preferably a single layer (monolayer). A single layer of protective film forming film is easy to produce because high precision can be obtained in thickness. In addition, if the protective film forming film is composed of multiple layers, there is a risk that the following problems may occur: the adhesion between the layers and the elasticity of each layer need to be considered, which may lead to the problem of peeling from the adherend. When the protective film forming film is a single layer, the above risks can be reduced and the degree of freedom in design is also high.

[0066] The thickness of the protective film-forming film may be less than 50 μm, 40 μm or less, or 30 μm or less. Alternatively, the thickness of the protective film-forming film may be 3 μm or more, 5 μm or more, 10 μm or more, or 15 μm or more.

[0067] The thickness of the protective film-forming film refers to the thickness of the entire protective film-forming film. For example, the thickness of a protective film-forming film composed of multiple layers refers to the total thickness of all layers constituting the protective film-forming film.

[0068] The protective film-forming film of this embodiment includes at least a filler (C). By controlling the number of fillers (C) having a predetermined shape and size when observing a cross-section parallel to the thickness direction of the cured protective film-forming film, heat conduction through the filler can be effectively performed in the cured protective film-forming film (protective film). As a result, even without increasing the amount of filler in the protective film, high heat dissipation properties can be achieved. Therefore, the effect of the filler amount on the adhesion reliability of the protective film can be suppressed, thereby achieving both heat dissipation properties and adhesion reliability of the protective film.

[0069] (1.2 Filling material)

[0070] In this embodiment, the number of fillers having a predetermined shape and size when observing a cross section parallel to the thickness direction of the cured protective film forming film (protective film) is controlled. Figures 1A to 2 Please explain in detail.

[0071] In this embodiment, if Figure 1A As shown, in the cross section of the filler 3, the longest diameter among the diameters of the filler is taken as the maximum length. Figure 1A In the figure, diameter L3 is the maximum length.

[0072] Furthermore, a circle is assumed that includes all the outer circumference lines constituting the outer circumference of the cross section of the filling material. Such a circle can be arbitrarily assumed. Figure 1B As shown, the circle with the smallest diameter among such circles is referred to as the minimum inclusion circle SEC. The minimum inclusion circle has the smallest diameter among the circles that include the entire cross section of the filler material.

[0073] In this embodiment, the cured protective film is cut along a plane parallel to the thickness direction to form a film. Figure 2 As shown, in the cross section obtained after cutting, a rectangular region RA is set with a side parallel to the thickness direction as one side. The length of the side parallel to the thickness direction is the same as the thickness of the protective film forming film 2 after curing, and the area of ​​the rectangular region RA is 625 μm 2 For example, if the thickness of the protective film forming film after curing is 25 μm, a 25 μm x 25 μm square region is defined in the cross-section of the cured protective film forming film. By using the cross-section parallel to the thickness direction as the observation region, it is possible to average out the unevenness of the filler's presence caused by the filler's precipitation that may occur during the production of the protective film forming film.

[0074] In this embodiment, the rectangular area RA is set, and the ratio of the cross-sectional area of ​​the filler to the area of ​​the minimum containing circle (cross-sectional area of ​​the filler / area of ​​the minimum containing circle of all outer circumferences of the cross-sectional area of ​​the filler) among the observed fillers 3 (3a, 3b, 3c) is 0.6 or more and 0.9 or less, and the maximum length of the cross-sectional area of ​​the filler is greater than 0.5 μm. Figure 2 In the figure, the filler material 3a) without hatching is controlled to be within a unit area (1 μm 2 ) is not less than 0.08 and not more than 0.80.

[0075] The filler material described above, where the ratio of the cross-sectional area of ​​the filler material to the area of ​​the smallest enclosing circle is 0.6 or more and 0.9 or less, is neither a spherical particle with a circular cross-section nor a highly anisotropic particle such as an amorphous particle. This shape facilitates contact between adjacent fillers at an area greater than the point contact between spheres, facilitating the formation of a wide heat conduction path through the filler material and increasing the amount of heat transferred. Furthermore, since the surface area per unit mass is not as large as that of amorphous particles (anisotropic particles), the amount of filler material required to ensure a heat conduction path can be reduced, ensuring the content of adhesive components in the protective film.

[0076] Furthermore, fillers with a maximum cross-sectional length of 0.5 μm or less tend to have a larger surface area due to their small particle size. Therefore, even with fillers having the aforementioned shapes, if more fillers with a maximum cross-sectional length of 0.5 μm or less are observed, the volume occupied by the filler in the protective film increases, tending to deteriorate the adhesion reliability of the protective film. Furthermore, since voids are easily formed in the protective film, this also tends to further deteriorate the adhesion reliability of the protective film. Therefore, fillers with a maximum cross-sectional length of 0.5 μm or less are not counted, regardless of the ratio of their cross-sectional area.

[0077] As described above, by setting the number of fillers having the predetermined shape and size to be within the above range, heat conduction via the filler can be performed efficiently, heat dissipation of the protective film can be ensured, and sufficient bonding reliability can be obtained.

[0078] On the other hand, when the protective film forming film contains a spherical filler, the cross-sectional shape of the filler is close to a circle, and the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest containing circle is close to 1. Therefore, when the protective film forming film contains a spherical filler, the number of fillers having the above-mentioned predetermined shape and size is likely to be less than 0.08 pieces / μm. 2 , it is difficult to form a wide heat conduction path through the filling material, so it is difficult to conduct heat sufficiently.

[0079] Furthermore, when the protective film forming film contains a filler material of amorphous particles, such as a plate-shaped filler material, the ratio of the cross-sectional area of ​​the filler material to the area of ​​the smallest containing circle becomes less than 0.6. Therefore, even if the protective film forming film contains a filler material of amorphous particles, the number of fillers having the above-mentioned predetermined shape and size is likely to be less than 0.08 pieces / μm. 2 In order to ensure a heat conduction path, the content of filler in amorphous particles increases, and the bonding reliability is likely to deteriorate.

[0080] In this embodiment, the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest included circle is 0.6 or more and 0.9 or less, and the maximum length of the cross section of the filler is greater than 0.5 μm. The number of fillers can be 0.10 or more / μm. 2 and less than 0.70 / μm 2 , can also be 0.11 or more / μm 2 and less than 0.50 / μm 2 .

[0081] In addition, when the area of ​​the above-mentioned rectangular region RA is set to 100%, it is preferred that the ratio of the total area occupied by the cross section of the filling material (C) in the rectangular region RA is not less than 30% and not more than 70%. The ratio of the total area occupied by the cross section of the filling material (C) (the ratio of the area occupied by the cross section) reflects the content of the filling material (C) in the protective film. In addition, the "filler (C)" in the total area occupied by the cross section of the filling material (C) is not limited to the filler material constituting the filler material having the above-mentioned specified shape and size, and includes a filler material having a shape or size different from the above-mentioned specific shape or size when observing the cross section parallel to the thickness direction of the protective film forming film after curing. Figure 2 In FIG. 1 , “filler (C)” represents the filler 3 a , the filler 3 b , and the filler 3 c .

[0082] When the ratio of the total area occupied by the filler (C) is within the above range, it is easier to achieve both heat dissipation properties and adhesion reliability of the protective film-forming film after curing.

[0083] The ratio of the total area occupied by the filler (C) may be 35% to 65%, or 40% to 60%.

[0084] (1.2.1. Method for determining filling materials)

[0085] As a method for observing the filler (C) including the filler having the above-mentioned predetermined shape and size, and a method for identifying the filler having the above-mentioned predetermined shape and size, any method can be used as long as the filler can be observed and identified in a cross-section of the protective film-forming film after curing. In this embodiment, a method of observing the cross-section of the protective film-forming film after curing using a scanning electron microscope (SEM) is exemplified.

[0086] A cross-sectional sample of the cured protective film can be prepared using a known polishing device. In this embodiment, the cross-sectional sample is prepared by ion polishing because the cross-sectional view is observed using a SEM. In ion polishing, an argon ion beam is irradiated onto the sample, processing the sample through sputtering.

[0087] The cross-sectional sample of the obtained protective film-forming film after curing is observed by SEM, and an SEM image is taken in the form of a still image. Through the SEM image, the boundary between the filler and the material other than the filler can be seen. As for the observation magnification, as long as the magnification of the above-mentioned rectangular area RA can be set in the observation field of view. In the observation field of view, an energy dispersive X-ray spectrometer (EDX) is used to detect elements that are contained in large quantities in the filler and are not contained or contained in small amounts in other components (such as components responsible for adhesion). For example, when the material of the filler is alumina, aluminum is detected.

[0088] In the mapping image of the element obtained by EDX, a set of pixels with a high content ratio of the above-mentioned element (e.g., aluminum) indicates that the position is a cross-section of the filling material. Furthermore, by applying the information of the mapping image obtained by EDX to the information of the boundary in the above-mentioned captured SEM image, the cross-section of the filling material in the SEM image and the positional relationship and boundary of materials other than the filling material can be determined. Thus, an SEM image that can determine the shape and size of the cross-section of the filling material can be produced. In addition, the SEM image that can determine the shape and size of the cross-section of the filling material can also be subjected to image processing such as anti-aliasing processing to produce an SEM image that makes the cross-section of the filling material and the positional relationship and boundary of materials other than the filling material clearer.

[0089] Using the SEM image that can determine the shape and size of the cross section of the filler, extract the rectangular area RA and measure the maximum length of the cross section of each filler present in the rectangular area RA. The maximum length can be measured manually or by image processing. Fillers with a maximum length of less than 0.5 μm (in Figure 2 In the figure, the hatched filler material 3b) is excluded from the subsequent measurements.

[0090] After measuring the maximum length, for each filler whose maximum cross-sectional length is greater than 0.5 μm, create a minimum circle containing all the outer peripheries of the cross-sectional area of ​​the filler. Based on the area of ​​the created minimum circle and the cross-sectional area of ​​the filler, calculate the ratio of the cross-sectional area of ​​the filler to the area of ​​the minimum circle (cross-sectional area of ​​the filler / area of ​​the minimum circle containing all the outer peripheries of the cross-sectional area of ​​the filler). Fillers whose calculated ratio is outside the range of 0.6 to 0.9 (in Figure 2 The filler material 3c marked with cross hatching is excluded, and the number of fillers with a ratio in the range of 0.6 to 0.9 is counted to calculate the per unit area (1 μm) in the rectangular area RA. 2 )

[0091] In this embodiment, the filler (C) preferably has a polyhedral shape. A polyhedron is a shape obtained by cutting the surface of a sphere along a predetermined plane. The polyhedron may be composed of flat or curved surfaces, and its vertices may be rounded. Figure 1C An example of a cross section of a filling material 3 in which a polyhedron is composed of planes is shown in FIG. Figure 1D An example of a cross section of a filler 3 having a polyhedron composed of curved surfaces is shown in FIG. By making the filler (C) a polyhedron, the number of fillers having the above-mentioned predetermined shape and size can easily satisfy the above-mentioned range.

[0092] The material of the filler (C) is not particularly limited as long as it is a material that improves thermal conductivity, and examples thereof include metals, metal oxides, carbonates, carbides, and nitrides.

[0093] In this specification, metal refers to an element belonging to Group 1 (excluding H), Groups 2 to 11, Group 12 (excluding Hg), Group 13 (excluding B), Group 14 (excluding C and Si), Group 15 (excluding N, P, As and Sb) or Group 16 (excluding O, S, Se, Te and Po) in the periodic table. As metal oxides, for example, magnesium oxide, titanium oxide, zinc oxide, aluminum oxide, boehmite, chromium oxide, nickel oxide, copper oxide, zirconium oxide, indium oxide and their composite oxides can be listed. As carbonates, magnesium carbonate, calcium carbonate etc. can be listed, as carbides, silicon carbide etc. can be listed, and as nitrides, boron nitride, aluminum nitride etc. can be listed. Among the above-mentioned materials, titanium oxide, aluminum oxide, aluminum nitride are preferred, and aluminum oxide is more preferred. Therefore, as filler (C), it is preferred to have polyhedral aluminum oxide.

[0094] In addition, for the filler material (C) having the above-mentioned prescribed shape and size, its material can also be listed as the same metals, metal oxides, carbonates, carbides, nitrides, etc. as mentioned above, preferably titanium oxide, aluminum oxide, aluminum nitride, and more preferably aluminum oxide.

[0095] In this embodiment, the thermal conductivity of the filler (C) is preferably 10W / (m·K) or more. By making the thermal conductivity within the above range, the heat dissipation of the protective film is improved. The thermal conductivity of the filler material can be 15W / (m·K) or more, or 20W / (m·K) or more, or 25W / (m·K) or more. The upper limit of the thermal conductivity of the filler material is, for example, 300W / (m·K). The thermal conductivity of the filler material (C) can be measured by, for example, a laser flash method using a laser flash method thermal conductivity measuring device (for example, LFA477 Nanoflash manufactured by NETZSCH-Geratebau GmbH). With regard to the thermal conductivity of the filler material (C), titanium oxide is approximately 10W / (m·K), aluminum oxide is approximately 30W / (m·K), and aluminum nitride is approximately 285W / (m·K).

[0096] In this embodiment, the average particle size of the filler (C) is preferably 0.8 μm to 5 μm. By setting the average particle size within the above range, the number of fillers having the above-mentioned predetermined shape and size is likely to fall within the above range.

[0097] The average particle size of the filler (C) may be 1 μm or more and 4 μm or less, 1.3 μm or more and 3.6 μm or less, or 1.6 μm or more and 3 μm or less.

[0098] In this specification, unless otherwise specified, the “average particle size” refers to the particle size (D50) at which the cumulative value is 50% in a particle size distribution curve determined by a laser diffraction scattering method.

[0099] In addition, in the particle size distribution showing the relationship between frequency and particle size, the particle size distribution of the filler (C) is preferably a unimodal distribution. When a plurality of powders with different average particle sizes are included, generally, the particle size distribution is a multimodal distribution. Therefore, when the particle size distribution of the filler (C) is a multimodal distribution, a plurality of fillers with different average particle sizes are included in the protective film. If a plurality of fillers with different average particle sizes are included in the protective film, the mutual contact of one filler material is hindered by another filler material, and sometimes it is difficult to form a broad heat conduction path. Therefore, in order to prevent the contact between fillers with equal particle sizes from being hindered, the particle size distribution of the filler (C) is preferably a unimodal distribution. In addition, when two or more fillers (for example, two or more fillers of different materials) are used as the filler (C), in this specification, the "particle size distribution of the filler (C)" refers to the particle size distribution when a mixed filler material in which all the fillers used are mixed is made.

[0100] The content of the filler (C) when the total weight of the protective film-forming film composition described later (i.e., the mass of the protective film-forming film) is 100 parts by mass can be from 65 parts by mass to 85 parts by mass, from 70 parts by mass to 83 parts by mass, or from 72 parts by mass to 82 parts by mass.

[0101] By setting the content of the filler within the above-mentioned range, the number of fillers having the above-mentioned predetermined shape and size is likely to fall within the above-mentioned range.

[0102] (1.3. Protective Film-Forming Composition)

[0103] The protective film-forming film is formed using a composition constituting the protective film-forming film (composition for forming a protective film). Specifically, the protective film-forming film contains the active ingredients constituting the composition for forming a protective film. Therefore, the composition for forming a protective film contains the aforementioned filler (C).

[0104] In this embodiment, the protective film-forming film composition preferably contains a polymer component (A) and a curable component (B) in addition to the aforementioned filler (C). The inclusion of these components allows the protective film-forming film to have film-forming properties and impart appropriate adhesiveness, further improving the adhesion between the protective film-forming film and the workpiece, thereby facilitating the formation of a protective film with highly reliable adhesion.

[0105] A polymer component is a component formed by a polymerization reaction of a polymerizable compound. In addition, a curable component is a component that can undergo a curing (polymerization) reaction. In addition, in the present invention, a polymerization reaction also includes a condensation reaction.

[0106] In addition, components contained in the polymer component may also be curable components. In this embodiment, when the protective film-forming film composition contains components that are both polymer components and curable components, it is considered that the protective film-forming film composition contains both polymer components and curable components.

[0107] (1.3.1 Polymer composition)

[0108] The polymer component (A) imparts film-forming properties to the protective film-forming film and imparts moderate adhesiveness to ensure that the protective film-forming film can be evenly adhered to the workpiece. The weight-average molecular weight of the polymer component is generally in the range of 50,000 to 2,000,000, preferably in the range of 100,000 to 1,500,000, and particularly preferably in the range of 200,000 to 1,000,000. Examples of such polymer components include acrylic resins, urethane resins, phenoxy resins, silicone resins, and saturated polyester resins, with acrylic resins being particularly preferred.

[0109] Examples of acrylic resins include (meth)acrylate copolymers composed of a (meth)acrylate monomer and a structural unit derived from a (meth)acrylic acid derivative. Preferred (meth)acrylate monomers include alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms, specifically methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic acid derivatives include (meth)acrylic acid, glycidyl (meth)acrylate, and hydroxyethyl (meth)acrylate.

[0110] In this embodiment, glycidyl methacrylate or the like is preferably used to introduce glycidyl groups into the acrylic resin. Acrylic resins with glycidyl groups have increased compatibility with the epoxy resin (described later as a thermosetting component), making it easier to form a uniform film, and tend to produce a stable protective film. Furthermore, in this embodiment, hydroxyethyl acrylate or the like is preferably used to introduce hydroxyl groups into the acrylic resin in order to control adhesion or tackiness to workpieces.

[0111] The glass transition temperature of the acrylic resin is preferably -70 to 40° C., -35 to 35° C., -20 to 30° C., -10 to 25° C., or -5 to 20° C. By setting the glass transition temperature of the acrylic resin within the above range, the adhesiveness of the protective film-forming film can be appropriately increased, and the adhesion between the protective film-forming film and the workpiece can be improved.

[0112] When an acrylic resin has m types of structural units (m is an integer greater than or equal to 2), the glass transition temperature of the acrylic resin can be calculated as follows. Specifically, when the m types of monomers from which the structural units in the acrylic resin are derived are each assigned a unique serial number from 1 to m and designated "monomer m," the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox equation shown below.

[0113] [Mathematical formula 1]

[0114]

[0115] (wherein, Tg is the glass transition temperature of the acrylic resin; m is an integer greater than or equal to 2; Tgk is the glass transition temperature of the homopolymer of monomer m; and Wk is the mass fraction of structural units m derived from monomer m in the acrylic resin, wherein Wk satisfies the following formula.)

[0116] [Mathematical formula 2]

[0117]

[0118] (where m and Wk are the same as those in the above formula 1)

[0119] As Tgk, the values ​​described in the Polymer Data Handbook, the Adhesion Handbook, or the Polymer Handbook can be used. For example, the Tgk of a homopolymer of methyl acrylate is 10°C, the Tgk of a homopolymer of n-butyl acrylate is -54°C, the Tgk of a homopolymer of 2-hydroxyethyl acrylate is -15°C, and the Tgk of a homopolymer of glycidyl methacrylate is 41°C.

[0120] The content of the polymer component, based on 100 parts by mass of the total weight of the protective film-forming composition (i.e., the mass of the protective film-forming film), can be 3 to 50 parts by mass, 5 to 40 parts by mass, 8 to 30 parts by mass, 10 to 25 parts by mass, or 11 to 20 parts by mass. By setting the content of the polymer component within the above range, the protective film-forming film can be provided with film-forming properties and at the same time impart appropriate viscosity, making it easier to adjust the adhesion between the protective film-forming film and the workpiece.

[0121] (1.3.2 Thermosetting components)

[0122] The curable component (B) cures the protective film-forming film to form a hard protective film. As the curable component, a thermosetting component, an energy ray curable component, or a mixture thereof can be used. As described above, the protective film-forming film is preferably thermosetting, so the curable component is also preferably a thermosetting component.

[0123] Preferred thermosetting components include epoxy resins, thermosetting polyimide resins, unsaturated polyester resins, and mixtures thereof. Furthermore, thermosetting polyimide resins are a general term for low-molecular-weight, low-viscosity monomers or precursor polymers that are thermally cured to form polyimide resins. Non-limiting examples of thermosetting polyimide resins are described in, for example, the Journal of the Japanese Society of Fiber Science, "Fibers and Industry," Vol. 50, No. 3 (1994), pp. 106-118.

[0124] The epoxy resin as a thermosetting component has the property of forming a three-dimensional network structure when heated, thereby forming a strong coating. As such epoxy resin, various known epoxy resins can be used. In the present embodiment, the molecular weight (formula weight) of the epoxy resin is preferably 300 or more and less than 50,000, 300 or more and less than 10,000, 300 or more and less than 5,000, or 300 or more and less than 3,000. In addition, the epoxy equivalent of the epoxy resin is preferably 50 to 5,000 g / eq, more preferably 100 to 2,000 g / eq, and further preferably 150 to 1,000 g / eq.

[0125] Specific examples of such epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenyl novolac, and cresol novolac; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidyl or alkyl glycidyl epoxy resins obtained by replacing the active hydrogen bonded to the nitrogen atom with a glycidyl group, such as aniline isocyanurate; and so-called alicyclic epoxy compounds such as vinylcyclohexane diepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane, in which epoxy groups are introduced by oxidizing the carbon-carbon double bond in the molecule. In addition to these, epoxy resins having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, etc. can also be used.

[0126] When a thermosetting component is used as the curing component (B), it is preferred to use a curing agent (D) as an auxiliary agent at the same time. For example, as a curing agent for epoxy resin, a heat-activated latent epoxy resin curing agent is preferred. "Heat-activated latent epoxy resin curing agent" refers to a type of curing agent that is not easy to react with epoxy resin at room temperature (23°C) and is activated by heating to a certain temperature or above, and then reacts with epoxy resin. Methods for activating heat-activated latent epoxy resin curing agents include a method of generating active species (anions, cations) through a chemical reaction based on heating; a method of stably dispersing in epoxy resin near room temperature, but being compatible with epoxy resin, dissolving and initiating a curing reaction at high temperature; a method of dissolving and initiating a curing reaction at high temperature using a molecular sieve encapsulated curing agent; a method based on microcapsules, etc.

[0127] Among the methods exemplified above, a method in which the epoxy resin is stably dispersed in the epoxy resin at around room temperature but is compatible with and dissolved in the epoxy resin at high temperature to initiate a curing reaction is preferred.

[0128] Specific examples of heat-activated latent epoxy resin curing agents include various onium salts, dibasic acid dihydrazide compounds, dicyandiamide, amine adduct curing agents, and high-melting-point active hydrogen compounds of imidazole compounds. These heat-activated latent epoxy resin curing agents may be used alone or in combination of two or more. In this embodiment, dicyandiamide is particularly preferred.

[0129] In addition, as a curing agent for epoxy resin, phenolic resin is also preferred. As the phenolic resin, condensates of phenols such as alkylphenols, polyphenols, naphthols and aldehydes can be used without particular limitation. Specifically, phenol novolac resin, o-cresol novolac resin, p-cresol novolac resin, tert-butylphenol novolac resin, dicyclopentadiene cresol resin, poly-p-vinyl phenolic resin, bisphenol A novolac resin or modified products thereof can be used.

[0130] The phenolic hydroxyl groups contained in these phenolic resins can easily undergo an addition reaction with the epoxy groups of the above-mentioned epoxy resins by heating, thereby forming a cured product with high impact resistance.

[0131] The content of the curing agent (D) can be 0.5 to 100 parts by mass, 1 to 30 parts by mass, 2 to 15 parts by mass, or 2.5 to 10 parts by mass relative to 100 parts by mass of the curable component (B). By setting the content of the curing agent (D) within the above range, the protective film can easily achieve the performance of protecting the workpiece.

[0132] When dicyandiamide is used as the curing agent (D), it is preferred to use a curing accelerator (E) simultaneously. Preferred curing accelerators include imidazoles (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms), such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Among these, 2-phenyl-4,5-dihydroxymethylimidazole is particularly preferred.

[0133] The content of the curing accelerator (E) can be 0.5 to 20 parts by mass, 1 to 15 parts by mass, or even 2 to 10 parts by mass relative to 100 parts by mass of the curable component (B). By setting the content of the curing accelerator (E) within the above range, the protective film can easily achieve the performance of protecting the workpiece.

[0134] The total content of the thermosetting component and the curing agent, based on 100 parts by mass of the total weight of the protective film-forming composition (i.e., the mass of the protective film-forming film), can be 3 to 50 parts by mass, 5 to 40 parts by mass, 8 to 30 parts by mass, 10 to 25 parts by mass, or 11 to 20 parts by mass. When the thermosetting component and the curing agent are blended in such a ratio, the protective film can easily achieve the performance of protecting the workpiece.

[0135] In particular, when the thermosetting component is an epoxy resin, the content of the epoxy resin can be 3 parts by mass or more, 5 parts by mass or more, or even 8 parts by mass or more per 100 parts by mass of the total weight of the protective film-forming composition (i.e., the mass of the protective film-forming film). By containing an epoxy resin in a predetermined amount or more, good curing properties are easily achieved.

[0136] (1.3.3. Energy-ray curable component)

[0137] When the curable component (B) is an energy ray-curable component, the energy ray-curable component is preferably uncured, preferably has adhesiveness, and more preferably is uncured and has adhesiveness.

[0138] The energy ray-curable component is a component that is cured by irradiation with energy rays, and is also a component for imparting film-forming properties, flexibility, and the like to the protective film-forming film.

[0139] As the energy-ray curable component, for example, a compound having an energy-ray curable group is preferable. As such a compound, a known compound having an energy-ray curable group can be mentioned.

[0140] (1.3.4 Colorants)

[0141] The protective film-forming film preferably contains a colorant (F). Thus, since the back of the processed singulated product of a workpiece such as a chip is covered, various electromagnetic waves generated in electronic devices can be shielded, and malfunctions of the singulated product of a workpiece such as a chip can be reduced.

[0142] As the colorant (F), known colorants such as inorganic pigments, organic pigments, and organic dyes can be used. In the present embodiment, inorganic pigments are preferred.

[0143] As inorganic pigment, for example, carbon black, cobalt pigment, iron pigment, chromium pigment, titanium pigment, vanadium pigment, zirconium pigment, molybdenum pigment, ruthenium pigment, platinum pigment, ITO (indium tin oxide) pigment, ATO (antimony tin oxide) pigment etc. can be listed.Wherein, particularly preferably use carbon black.Through carbon black, it is possible to shield electromagnetic waves of wider wavelength range.

[0144] The amount of colorant incorporated into the protective film-forming film varies depending on the thickness of the protective film-forming film. For example, when the protective film-forming film has a thickness of 25 μm, the colorant content per 100 parts by mass of the total weight of the protective film-forming film composition (i.e., the mass of the protective film-forming film) may be 0.2 to 5 parts by mass, or 0.5 to 3 parts by mass.

[0145] The average particle size of the inorganic pigment is preferably 1 to 500 nm, particularly preferably 3 to 100 nm, and further preferably 5 to 50 nm. If the average particle size of the inorganic pigment is within the above range, it is easy to control the light transmittance within the desired range.

[0146] (1.3.5 Coupling Agent)

[0147] The protective film-forming film preferably contains a coupling agent (G). The inclusion of a coupling agent can improve the adhesion between the protective film and the workpiece, while also improving water resistance (resistance to moist heat) without compromising the heat resistance of the protective film after curing. As a coupling agent, a silane coupling agent is preferred from the perspectives of versatility and cost advantages.

[0148] Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfide, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazolesilane. These silane coupling agents may be used alone or in combination of two or more.

[0149] The content of the coupling agent when the total weight of the protective film-forming composition (i.e., the mass of the protective film-forming film) is 100 parts by mass may be 0.005 to 1 part by mass, 0.01 to 0.5 parts by mass, 0.015 to 0.3 parts by mass, or 0.02 to 0.1 parts by mass.

[0150] (1.3.6 Other additives)

[0151] The protective film-forming composition may contain other additives such as photopolymerization initiators, ultraviolet absorbers, crosslinking agents, plasticizers, antistatic agents, antioxidants, gettering agents, tackifiers, and release agents, as long as the effects of the present invention are not impaired. The content of these other additives, based on 100 parts by mass of the total weight of the protective film-forming composition (i.e., the mass of the protective film-forming film), may be less than 4 parts by mass or less than 2 parts by mass.

[0152] (2. Protective Film Forming Sheet and Protective Film Forming Composite Sheet)

[0153] The protective film-forming film is usually used in the form of a protective film-forming sheet or a protective film-forming composite sheet. The protective film-forming sheet is used to attach the protective film-forming film to a workpiece and form a protective film on the workpiece or a singulated product of the workpiece (singulated product of the workpiece). The protective film-forming composite sheet is used to attach to the workpiece and hold the workpiece during processing, while attaching the protective film-forming film to the workpiece and forming a protective film on the workpiece or a singulated product of the workpiece (singulated product of the workpiece).

[0154] The protective film forming sheet 10 has Figure 3 The protective film forming film 1 has two opposing main surfaces, namely the main surface 1a and the main surface 1b. A first release film 21 supporting the protective film forming film 1 is arranged on the main surface 1a, and a second release film 22 supporting the protective film forming film 10 is arranged on the main surface 1b.

[0155] When Figure 3 When release films are formed on both main surfaces of the protective film forming film, it is preferred that one release film has a larger release force to form a heavy release film, and the other release film has a smaller release force to form a light release film.

[0156] The protective film-forming sheet is preferably a long sheet capable of forming multiple protective film-forming films to be attached to a workpiece. Furthermore, the protective film-forming sheet is preferably a roll formed by winding the long sheet. Alternatively, the protective film-forming sheet may be a single sheet obtained by cutting the long sheet to form a single protective film-forming film to be attached to a workpiece. Furthermore, the protective film-forming sheet may include either a first release film or a second release film.

[0157] The composite sheet for forming a protective film comprises a protective film-forming film and a support sheet for supporting the protective film-forming film. The support sheet has a structure capable of supporting the protective film-forming film (excluding a release film). As an example of the support sheet, an adhesive sheet having a substrate and an adhesive layer can be exemplified.

[0158] Specifically, if Figure 4As shown, the composite sheet 11 for forming a protective film has the following configuration: an adhesive sheet 40 serving as a support sheet, formed by laminating an adhesive layer 42 on one surface of a substrate 41; a protective film-forming film 1 laminated on the adhesive layer 42 of the adhesive sheet 40 with its main surface 1a in contact with the adhesive layer 42 of the adhesive sheet 40; and a release film 23 disposed on the main surface 1b of the protective film-forming film 1. Furthermore, a jig adhesive layer (not shown) may be disposed on the periphery of the protective film-forming film 1. The jig adhesive layer is a layer used to adhere the composite sheet for forming a protective film to a jig such as a ring frame.

[0159] Furthermore, it is preferable that each of the first release film 21 , the second release film 22 , and the release film 23 is a release film in which a silicone-based release agent layer is formed on one surface of a polyethylene terephthalate (PET) film.

[0160] (3. Production of protective film-forming film)

[0161] The protective film-forming film can be produced by a known method. For example, the protective film-forming film composition described above or a composition obtained by diluting the protective film-forming film composition with a solvent (these compositions are referred to as "coating agents") can be used to produce the protective film-forming film. The coating agent can be prepared by mixing the components constituting the protective film-forming film composition by a known method.

[0162] The resulting coating agent is applied to the release surface of the first release film using a coating machine such as a roll coater, knife coater, roll knife coater, air knife coater, die coater, rod coater, gravure coater, or curtain coater. If necessary, the solvent in the coating agent is removed by drying to form a protective film-forming film on the first release film.

[0163] When producing the protective film-forming sheet, the sheet can be obtained by further laminating the release surface of the second release film to the exposed surface of the protective film-forming film formed on the first release film.

[0164] In addition, when manufacturing a composite sheet for forming a protective film, a laminate comprising an adhesive sheet and the above-mentioned protective film forming sheet can be used. The adhesive sheet can be manufactured by a known method. For example, a composition constituting the adhesive layer of the adhesive sheet is prepared and applied to the release surface of the third release film, and dried as needed to form an adhesive layer on the third release film. Then, a substrate is laminated on the exposed adhesive layer to obtain an adhesive sheet having the third release film configured on the adhesive layer.

[0165] Next, the second release film of the protective film-forming sheet is peeled off, and the third release film of the adhesive sheet is peeled off. The protective film-forming film and the adhesive layer are then bonded together to form a composite sheet for forming a protective film. If necessary, after peeling off the first release film, a jig adhesive layer is formed around the exposed adhesive layer.

[0166] Furthermore, the protective film-forming film can be punched out to the size of an adherend (eg, a wafer) to be attached, or a size close to the size of the adherend, as needed.

[0167] (4. Method for manufacturing single-piece workpieces with protective films)

[0168] The method for producing a singulated workpiece with a protective film according to this embodiment comprises at least the following steps 1 to 3:

[0169] Step 1: a step of attaching the protective film-forming film to a workpiece;

[0170] Step 2: After the step of attaching to the workpiece, the step of curing the attached protective film forming film;

[0171] Step 3: After the step of attaching to the workpiece, the step of singulating the workpiece to which the protective film or protective film-forming film has been attached, thereby obtaining a plurality of singulated workpieces with the protective film or protective film-forming film.

[0172] In addition, as is clear from the above description, as long as it is performed after step 1, step 2 may be performed before step 3 or after step 3.

[0173] use Figure 5A 、 Figure 5B and Figure 6 , a method for manufacturing a workpiece singulated product with a protective film having the above-mentioned steps 1 to 3 will be described.

[0174] Hereinafter, as an example of a method for producing singulated workpieces with a protective film using the protective film forming sheet or protective film forming composite sheet of this embodiment, a method for producing chips with a protective film obtained by processing a wafer with a protective film formed thereon will be described.

[0175] like Figure 5A As shown, the protective film forming film 1 of the protective film forming sheet 10 with the second release film 22 removed is attached to the back surface of the wafer 100 (step 1). The first release film 21 may be peeled off after step 1 as needed.

[0176] In addition, if Figure 5B As shown, the protective film-forming film 1 of the protective film-forming composite sheet 11 is attached to the back surface of the wafer 100 (step 1). At this time, the clamp provided on the outer periphery of the protective film-forming film 1 can be attached to the ring frame 150 with an adhesive layer 50 and fixed. The surface of the protective film-forming film 1 opposite to the surface in contact with the adhesive layer 42 is attached to the back surface of the wafer 100. When attaching the protective film-forming film 1 to the wafer 100, the protective film-forming film 1 can be heated as desired to activate its adhesive properties.

[0177] Then, the attached protective film forming film 1 is cured to form a protective film (process 2), and a wafer with a protective film is obtained. When the protective film forming film is thermosetting, the protective film forming film is heated at a specified temperature for an appropriate time. For example, the heating temperature during thermal curing of the protective film forming film can be 100~200°C, 110~170°C, or 120~150°C. In addition, the heating time during thermal curing can be 0.5~5 hours, 0.5~4 hours, or 1~3 hours. The protective film obtained by thermal curing is preferably slowly cooled to room temperature. The method of slow cooling is not particularly limited, and it can be natural cooling. In addition, when the protective film forming film is energy ray curable, it can be irradiated with energy rays from the adhesive sheet or the peeling film side.

[0178] The protective film forming film may be cured after the singulation (eg, dicing) step, or after the chip with the protective film forming film is picked up from the adhesive sheet.

[0179] Then, as needed, Figure 5A The protective film forming film 1 shown is cured and the wafer 100 with the protective film and the ring frame 150 are attached to a known cutting sheet 80, and the wafer 100 with the protective film is singulated (for example, cut) to obtain the following: Figure 6 The chip with the protective film 2 (chip 101 with protective film) is shown. Alternatively, Figure 5A The wafer 100 with the protective film forming film 1 and the ring frame 150 shown are attached to a known dicing sheet 80, and the wafer 100 with the protective film forming film is singulated (for example, cut) to obtain chips with the protective film forming film 1 (chips with the protective film forming film) (process 3).

[0180] In addition, by known methods, Figure 5B The protective film-forming film 1 shown in FIG. 1 is cured and the wafer 100 with the protective film is singulated (eg cut) to obtain the wafer 100 shown in FIG. Figure 6 The chip with the protective film 2 (chip 101 with protective film) is shown. Alternatively, Figure 5B The wafer 100 with the protective film forming film 1 shown is singulated (eg, diced) to obtain chips having a protective film forming film (chips with a protective film forming film) (step 3).

[0181] The obtained chip with a protective film is picked up and mounted on a substrate etc. The chip with a protective film forming film is mounted on a substrate etc. after curing the protective film forming film.

[0182] In the chip with a protective film thus obtained, the number of fillers having the above-mentioned predetermined shape and size in the protective film satisfies the above-mentioned relationship. As a result, both the heat dissipation property of the protective film and the adhesive reliability can be achieved.

[0183] As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited at all to the said embodiment, It can change in various aspects within the scope of this invention.

[0184] Example

[0185] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0186] (Production of Protective Film Forming Sheet)

[0187] Using a coating agent containing the protective film-forming film composition described below, a protective film-forming sheet containing a thermosetting protective film-forming film was produced in the following manner.

[0188] (Coating agent containing protective film-forming composition)

[0189] The following components were mixed at the mass ratio (in terms of solid content) shown in Table 1, and diluted with methyl ethyl ketone to a solid content concentration of 65% by mass to prepare a coating agent containing a protective film-forming film composition.

[0190] (A) Polymer component

[0191] (A-1) A (meth)acrylate copolymer (weight average molecular weight: 400,000, glass transition temperature: -1°C) obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate.

[0192] (A-2) A (meth)acrylate copolymer obtained by copolymerizing 85 parts by mass of methyl acrylate and 15 parts by mass of 2-hydroxyethyl acrylate (weight average molecular weight: 400,000, glass transition temperature: 6° C.)

[0193] (B) Curable component (thermosetting component)

[0194] (B-1) Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent weight 184 to 194 g / eq)

[0195] (B-2) Dicyclopentadiene epoxy resin (manufactured by DIC Corporation, EPICLON HP-7200HH, epoxy equivalent weight 274 to 286 g / eq)

[0196] (C) Filling material

[0197] (C-1) Alumina filler (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, AA-1.5, polyhedral, average particle size 1.7 μm)

[0198] (C-2) Alumina filler (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, AA-2, polyhedral, average particle size 2.2 μm)

[0199] (C-3) Alumina filler (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, AA-3, polyhedral, average particle size 3.5 μm)

[0200] (C-4) Alumina filler (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, AA-10, polyhedral, average particle size 13.5 μm)

[0201] (C-5) Alumina filler (manufactured by SUMITOMO CHEMICAL COMPANY, LIMITED, AA-03F, polyhedral, average particle size 0.26 μm)

[0202] (C-6) Alumina filler (manufactured by Resonac Holdings Corporation, CB-P02, spherical, average particle size 3 μm)

[0203] (D) Curing agent

[0204] (D-1) Dicyandiamide (manufactured by Mitsubishi Chemical Corporation, DICY7)

[0205] (E) Curing accelerator

[0206] (E-1) 2-Phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Chemicals Corporation, Curezol 2PHZ)

[0207] (F) Colorant

[0208] (F-1) Carbon black (manufactured by Mitsubishi Chemical Corporation, MA-600B, average particle size 28 nm)

[0209] (G) Coupling agent

[0210] (G-1) Silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403)

[0211] [Table 1]

[0212]

[0213] A first release film (SP-PET502150, manufactured by LINTEC Corporation) was prepared, in which a silicone release agent layer was formed on one side of a 50 μm thick polyethylene terephthalate (PET) film. Furthermore, a second release film (SP-PET381031, manufactured by LINTEC Corporation) was prepared, in which a silicone release agent layer was formed on one side of a 38 μm thick polyethylene terephthalate (PET) film.

[0214] A coating agent containing each protective film-forming film composition was applied to the release-treated surface of the first release film and dried at 100°C for 2 minutes to form a 25 μm-thick protective film-forming film. Next, the release-treated surface of the prepared second release film was attached to the surface of the protective film-forming film, yielding a protective film-forming sheet with release films disposed on both sides of the protective film-forming film. The attachment conditions were as follows: temperature 60°C, pressure 0.4 MPa, and speed 1 m / min.

[0215] The following measurements and evaluations were performed using the obtained protective film-forming sheet.

[0216] (Number of fillers having the above-mentioned predetermined shape and size)

[0217] The obtained protective film forming sheet was placed in an environment of 140°C for 2 hours to completely cure the protective film forming film, and the first peeling film and the second peeling film were removed. As preparation for making a sample having a cross section parallel to the thickness direction of the cured protective film forming film, a cover glass, an adhesive, a cured protective film forming film, an adhesive, and a cover glass were stacked on a tungsten sample stand and left to stand for 24 hours, thereby loading a sample in which the adhesive was completely cured (ion polishing sample). In addition, as a method for easily obtaining a cross section suitable for observation by ion polishing, the end of the ion polishing sample was loaded in a manner that exposed 1 mm from the tungsten sample stand. In addition, the above-mentioned adhesive used was a product named "Bond Quick 5" manufactured by KONISHI Co., Ltd., and the cover glass used was a product named "square cover glass 18×18 NO.1" manufactured by Matsunami Glass Ind., Ltd.

[0218] The prepared sample was placed on a cross-section polisher (manufactured by JEOL Ltd., product name "SM-09010 CROSSSECTION POLISHER") and ion polished under the following processing conditions to prepare a sample having a cross section parallel to the thickness direction of the cured protective film-forming film.

[0219] (Processing conditions)

[0220] Introduced gas: Argon (adjust the amount of gas introduced so that the current reaches 80% of the maximum output power)

[0221] Ion acceleration voltage: 4.1kV

[0222] Sample swing: ±30°

[0223] Processing time: 48 hours (intermittent processing at 10-second intervals)

[0224] Cross-sections of the resulting samples were examined using an SEM (ZEISS GeminiSEM 560, manufactured by ZEISS Microscopy). SEM images were captured as still images to obtain information on the boundaries between the filler and other materials. Furthermore, since the filler was made of alumina, an energy-dispersive X-ray spectrometer (EDX) was used to obtain aluminum mapping images. EDX mapping was performed by applying a 15 kV voltage for only a sufficient time (5 to 40 minutes) to clearly identify each region represented by the boundary in the SEM image as representing the filler (alumina).

[0225] By applying the information of the mapping image obtained by EDX to the information of the boundary of the above-mentioned SEM image, the cross-section of the filling material and the positional relationship and boundary of the area other than the filling material in the above-mentioned SEM image are determined, and an SEM image that can determine the shape and size of the cross-section of the filling material is produced. Next, using image processing software (GIMP), the brightness of the pixels belonging to the area constituting the cross-section of the filling material is set to 255, and the brightness of the pixels belonging to the area other than the cross-section is set to 40, thereby performing anti-aliasing processing based on binarization on the cross-section of the filling material and the area other than the cross-section, and then extracting the thickness of the protective film formed after curing as one edge and setting the area to 625μm 2 The rectangular area RA.

[0226] The maximum length of the cross section of each filling material present in the rectangular area RA extracted from the SEM image after the anti-aliasing process is measured. For the filling material whose maximum length of the cross section present in the rectangular area RA is greater than 0.5 μm, for each cross section of the filling material, the minimum containing circle of all the outer peripheral lines of the cross section containing the filling material is mapped. The total number of pixels belonging to the area constituting the minimum containing circle is taken as the area of ​​the minimum containing circle, and the total number of pixels belonging to the area constituting the filling material as the object of mapping the minimum containing circle is taken as the cross-sectional area of ​​the filling material, and "(cross-sectional area of ​​the filling material) / (area of ​​the minimum containing circle of all the outer peripheral lines of the cross section containing the filling material)" is calculated. This operation is performed on all filling materials whose maximum length of the cross section present in the rectangular area RA is greater than 0.5 μm. Then, the number of filling materials whose "(cross-sectional area of ​​the filling material) / (area of ​​the minimum containing circle of all the outer peripheral lines of the cross section containing the filling material)" is within the range of 0.6 to 0.9 is calculated, and the number of filling materials per unit area (1 μm 2 ) (pieces / μm 2 The results are shown in Table 2.

[0227] If the minimum enclosing circle of a filler material included in the calculation includes fillers other than the filler material, the brightness of the fillers other than the filler material is temporarily set to 40, and the area of ​​the minimum enclosing circle is calculated. Furthermore, if any side of the rectangular area RA coincides with the outer perimeter of a filler material, that filler material is not counted, even if it is a filler material with the specified shape and size.

[0228] (Area ratio of the cross section of the filler (C))

[0229] In the extracted rectangular region RA included in the anti-aliased SEM image, the total number of pixels belonging to the rectangular region RA was set as the area of ​​the rectangular region RA, and the total number of pixels belonging to the region constituting the cross-section of all the filler (C) present in the rectangular region RA was set as the area occupied by the cross-section of the filler (C). The ratio of the total area occupied by the cross-section of the filler (C) in the rectangular region RA was calculated (100 × (total area occupied by the cross-section of the filler (C)) / (area of ​​the rectangular region RA)) (%). The results are shown in Table 2.

[0230] (Thermal conductivity of the protective film-forming film after curing)

[0231] The obtained protective film forming sheet is placed in an environment of 140°C for 2 hours to completely cure the protective film forming film, and the first peeling film and the second peeling film are removed. Next, the thermal diffusivity of the cured protective film forming film is measured using a thermal diffusivity and thermal conductivity measuring device (manufactured by Ai Phase, product name "ai-Phase Mobile 1u") in an environment of 23°C and a relative humidity of 50%. Measurements are performed at 10 locations within the surface of the cured protective film forming film. Among the 10 obtained measurement data, one data showing the minimum value and five data from the maximum value to the fifth data are removed, and the average value of the remaining 4 data is used as the thermal diffusivity of the cured protective film forming film. Using the obtained thermal diffusivity, the thermal conductivity of the cured protective film forming film is calculated by the following calculation formula. In addition, the specific heat of the cured protective film forming film monomer is calculated by the DSC method, and the density is calculated by the Archimedes method. In this embodiment, samples with a thermal conductivity of 3.0W / (m·K) or more are judged to be good. The results are shown in Table 2.

[0232] Calculation formula: Thermal conductivity (W / (m·K)) = thermal diffusivity × density × specific heat

[0233] (Utilization rate of filler (C))

[0234] The utilization rate of the filler (C) was calculated using the cross-sectional area ratio of the filler (C) obtained above and the thermal conductivity of the cured protective film-forming film (thermal conductivity of the cured protective film-forming film / cross-sectional area ratio of the filler (C)). In this example, samples with a utilization rate of 0.057 or greater were considered good. The results are shown in Table 2.

[0235] (Adhesion reliability of protective film-forming film after curing)

[0236] The second release film of the protective film forming sheet obtained was peeled off, and the silicon wafer was attached to the polished surface of a silicon wafer (diameter: 200 mm, thickness: 280 μm) that had been polished to #2000 while being heated to 70°C using a film laminator (manufactured by LINTEC Corporation, product name "Adwill RAD-3600 F / 12") to produce a silicon wafer with a protective film forming film.

[0237] The first release film of the produced silicon wafer with a protective film forming film was peeled off, and the wafer was placed in an environment of 140° C. for 2 hours to completely cure the protective film forming film, thereby producing a silicon wafer with a protective film (cured protective film forming film).

[0238] In the silicon wafer with a protective film produced, a dicing tape (manufactured by LINTEC Corporation, product name "Adwill D-676H") is attached to the exposed side of the protective film, and a dicing device (manufactured by DISCO Corporation, product name "DFD651") is used to cut the silicon wafer into a size of 3 mm × 3 mm to obtain a chip with a protective film (the protective film forms a film after curing).

[0239] 25 chips with protective films were placed in a thermal shock apparatus (manufactured by ESPEC, product name "TSE-11A"), and "maintaining at -65°C for 10 minutes and then at 150°C for 10 minutes" was repeated 1000 times as a cycle.

[0240] The cross section of the chip with the protective film removed from the thermal shock apparatus was then observed using a scanning ultrasonic flaw detector (Hype-Focus, manufactured by Hitachi Construction Machinery Co., Ltd.) to check for any lifting, peeling, or cracking of the protective film at the junction between the chip and the protective film.

[0241] Chips with protective films that showed any of the following: lifting, peeling, or cracking of the protective film were judged "NG." Table 2 shows the number of chips with protective films judged "NG" among the 25 observed chips. In this example, samples with 10 or fewer chips judged "NG" were judged as good.

[0242] [Table 2]

[0243]

[0244] It can be confirmed from Table 2 that when a filler satisfying the above relationship is used, both the heat dissipation property of the protective film and the adhesion reliability can be achieved.

Claims

1. A protective film-forming film, which is a curable protective film-forming film containing a filler, wherein: In a cross section parallel to the thickness direction of the protective film-forming film after curing, a length equal to the thickness in the thickness direction is observed as one side and the area is 625 μm. 2 In the case of a rectangular area, the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest circle containing all the outer circumferences of the cross-sectional area of ​​the filler is 0.6 or more and 0.9 or less, and the maximum length of the cross-sectional area of ​​the filler is greater than 0.5 μm, and the ratio of the cross-sectional area of ​​the filler to the area of ​​the smallest circle containing all the outer circumferences of the cross-sectional area of ​​the filler is 0.08 or more / μm. 2 and less than 0.80 / μm 2 exist.

2. The protective film-forming film according to claim 1, wherein The protective film-forming film includes a curable component and a polymer component.

3. The protective film-forming film according to claim 1 or 2, wherein The average particle size of the filler is not less than 0.8 μm and not more than 5 μm.

4. The protective film-forming film according to claim 1 or 2, wherein The particle size distribution of the filler material is unimodal.

5. The protective film-forming film according to claim 1 or 2, wherein The protective film-forming film has a thickness of less than 50 μm.

6. The protective film-forming film according to claim 1 or 2, wherein The filling material is made of aluminum oxide.

7. The protective film-forming film according to claim 1 or 2, wherein When the area of ​​the rectangular region is defined as 100%, the ratio of the cross section of the filler to the total area in the rectangular region is not less than 30% and not more than 70%.

8. A method for manufacturing a singulated workpiece with a protective film, comprising: a step of attaching the protective film-forming film according to any one of claims 1 to 7 to a workpiece; After the step of attaching the film to the workpiece, a step of curing the protective film-forming film; and After the step of attaching the workpiece to the workpiece, a step of singulating the workpiece to which the protective film or protective film-forming film is attached, thereby obtaining a plurality of singulated workpieces with the protective film or protective film-forming film.

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