Protective film-forming film, protective film-forming sheet, protective film-forming composite sheet, rework method and device manufacturing method

Abstract

To provide a protective film-forming film that exhibits good reworkability even when the protective film-forming film that has been scratched after application is reworked, a protective film-forming sheet and a protective film-forming composite sheet including the same, a rework method, and a method of manufacturing of a device such as a semiconductor device.SOLUTION: In a protective film-forming film 10 for forming a protective film, the elongation rate when the protective film-forming film 10 breaks in the right angle tear test is 200% or less at 23°C, and the adhesive strength to the silicon wafer after one hour since attaching the protective film-forming film 10 to the #2000 polished surface of a silicon wafer (workpiece 6) is 20 N / 25 mm or less at 23°C.SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a protective film-forming film, a sheet for forming a protective film, a composite sheet for forming a protective film, a rework method, and a method for manufacturing an apparatus. In particular, the present invention relates to a protective film-forming film that is suitably used for protecting a workpiece such as a semiconductor wafer or a processed product such as a semiconductor chip obtained by processing the workpiece, a sheet for forming a protective film and a composite sheet for forming a protective film that include the protective film-forming film, a rework method, and a method for manufacturing an apparatus that includes a semiconductor chip or the like. [Background technology]

[0002] In recent years, semiconductor devices have been manufactured using a mounting method called flip-chip bonding. In this mounting method, when mounting a semiconductor chip having a circuit surface on which convex electrodes such as bumps are formed, the semiconductor chip is turned face-down so that the circuit surface of the semiconductor chip faces the chip-mounting surface of the substrate, and the circuit surface of the semiconductor chip and the chip-mounting surface of the substrate are wirelessly bonded. Therefore, the surface of the semiconductor chip opposite the circuit surface (the surface on which no circuits are formed; hereinafter, also referred to as the back surface) is exposed to the outside.

[0003] If the back surface of a semiconductor chip is exposed to the outside, chipping such as cracks or chips may occur in subsequent processes due to impacts during transportation, etc. Therefore, to protect the semiconductor chip from such chipping, a hard resin film made of an organic material is often formed as a protective film on the back surface of the semiconductor chip.

[0004] Such a protective film is formed by curing its precursor, an uncured resin film (hereinafter also referred to as a protective film-forming film). The protective film-forming film is attached to the back surface of a semiconductor wafer, and before or after the protective film-forming film is cured, the semiconductor wafer and the protective film-forming film or protective film are diced and divided into a plurality of small pieces (single pieces). The divided small pieces are semiconductor chips having a protective film on their back surfaces (semiconductor chips with a protective film).

[0005] However, in the process of attaching the protective film-forming film to the semiconductor wafer, there are cases where the protective film-forming film is not properly attached to the semiconductor wafer, such as when the protective film is attached at a position other than the intended position, or when wrinkles occur in the attached protective film.

[0006] If a protective film-forming film is not properly attached to a semiconductor wafer, there is a problem that the yield of protective film-coated chips decreases. Therefore, if the protective film-forming film is not properly attached, the protective film-forming film is peeled off from the semiconductor wafer to return the semiconductor wafer to the state before the protective film-forming film was attached. This is called rework. Then, a protective film-forming film different from the peeled protective film is attached to the semiconductor wafer.

[0007] As a protective film-forming film suitable for rework, Patent Document 1 discloses a protective film-forming sheet that contains a predetermined acrylic polymer and has a breaking elongation within a predetermined range at a thickness of 200 μm. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-141749 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the present inventors have found that when the attached protective film-forming film is scratched to cause portions of the protective film-forming film to be non-uniform in thickness, when the protective film-forming film is peeled off from the semiconductor wafer for rework, a portion of the protective film-forming film remains on the semiconductor wafer as a residue. When such residue is generated, the semiconductor wafer needs to be cleaned, which causes problems such as an increase in the number of processes.

[0010] Furthermore, the present inventors have found that such residues are residues resulting from stretching and breaking of the protective film-forming film caused by unevenness in thickness in the vicinity of scratches in the protective film-forming film.

[0011] Conventionally, in rework based on misalignment, wrinkles, etc. of the protective film-forming film, the protective film-forming film having a uniform thickness is peeled off, and therefore residues due to the high adhesive strength of the protective film-forming film to the semiconductor wafer have been a problem. In other words, the cause of residues differs depending on whether the protective film-forming film has scratches or not.

[0012] Therefore, the sheet for forming a protective film described in Patent Document 1 has a problem in that when a scratched sheet for forming a protective film is reworked, it is unable to exhibit good reworkability and residue is generated.

[0013] The present invention has been made in consideration of the above-described circumstances, and aims to provide a protective film-forming film that has good reworkability even when reworking a protective film-forming film that has been damaged during or after application, a protective film-forming sheet and a protective film-forming composite sheet that include the same, as well as a rework method and a method for manufacturing devices such as semiconductor devices. [Means for solving the problem]

[0014] The aspects of the present invention are as follows. [1] A protective film-forming film for forming a protective film, The elongation rate at which the protective film-forming film breaks in a right-angle tear test is 200% or less at 23°C, This protective film-forming film has an adhesive strength to the silicon wafer of 20 N / 25 mm or less at 23°C one hour after application to the #2000 polished surface of the silicon wafer. [2] The protective film-forming film according to [1], wherein the protective film-forming film is heat-curable or energy ray-curable. [3] A sheet for forming a protective film, comprising the protective film-forming film according to [1] or [2] and a release film releasably arranged on at least one main surface of the protective film-forming film. [4] A composite sheet for forming a protective film, comprising the protective film-forming film according to [1] or [2] and a support sheet that supports the protective film-forming film. [5] A step of attaching the protective film-forming film according to [1] or [2] to the back surface of the workpiece; A step of inspecting the appearance of the attached protective film-forming film; This rework method includes a step of inspecting the appearance of the applied protective film-forming film, and if a scratch is found in the applied protective film-forming film, a step of peeling off the damaged protective film-forming film from the workpiece. [6] A step of attaching the protective film-forming film according to [1] or [2] to the back surface of the workpiece; A step of inspecting the appearance of the attached protective film-forming film; a step of peeling off the damaged protective film-forming film from the workpiece when a scratch is found on the attached protective film-forming film in a step of inspecting the appearance of the attached protective film-forming film; A step of attaching a protective film-forming film according to [1] or [2] to the back surface of the workpiece, which is different from the protective film-forming film peeled off from the workpiece; a step of forming the protective film-forming film into a protective film to obtain a workpiece with a protective film; and a step of processing the workpiece with the protective film to obtain a workpiece with the protective film. [Effects of the Invention]

[0015] According to the present invention, even when reworking a protective film-forming film that has been damaged during or after application, it is possible to provide a protective film-forming film that has good reworkability, a protective film-forming sheet and a protective film-forming composite sheet that include the same, as well as a rework method and a method for manufacturing devices such as semiconductor devices. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a workpiece to which a protective film-forming film according to this embodiment is attached. [Figure 2A] FIG. 2A is a perspective schematic view showing a scratched portion occurring in the protective film-forming film attached to the workpiece. [Figure 2B] FIG. 2B is a schematic cross-sectional view taken along line IIB-IIB in FIG. 2A. [Figure 3A] FIG. 3A is a schematic plan view showing a state immediately after starting to peel off the protective film-forming film from a workpiece to which the protective film-forming film according to the conventional example is attached. [Figure 3B] FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB in FIG. 3A. [Figure 3C] FIG. 3C is a continuation of FIG. 3A. [Figure 3D] FIG. 3D is a continuation of FIG. 3B. [Figure 3E] FIG. 3E is a continuation of FIG. 3C. [Figure 3F] FIG. 3F is a continuation of FIG. 3D. [Figure 4A] FIG. 4A is a schematic plan view showing a state in which the protective film-forming film according to the present embodiment is peeled off from the workpiece to which the protective film-forming film is attached, and the peeled interface reaches a damaged portion. [Figure 4B] FIG. 4B is a schematic cross-sectional view taken along line IVB-IVB in FIG. 4A. [Figure 5] FIG. 5 is a cross-sectional view showing an example of the sheet for forming a protective film according to this embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing an example of the composite sheet for forming a protective film according to this embodiment. [Figure 7A] FIG. 7A is a schematic cross-sectional view for explaining a step of attaching the protective film forming sheet according to this embodiment to the back surface of a workpiece. [Figure 7B] FIG. 7B is a cross-sectional view illustrating a process of attaching the composite sheet for forming a protective film according to this embodiment to the rear surface of a workpiece. [Figure 8]FIG. 8 is a schematic cross-sectional view for explaining a process of dicing a work with a protective film to obtain chips with a protective film. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below based on specific embodiments with reference to the accompanying drawings. First, the main terms used in this specification will be explained.

[0018] The workpiece is a plate-like body to which the protective film-forming film provided in the protective film-forming sheet or the protective film-forming composite sheet according to this embodiment is attached and processed. Examples of the workpiece include wafers and panels. Specifically, examples include semiconductor wafers and semiconductor panels. Examples of the workpiece include chips obtained by dividing a wafer. Specifically, examples include semiconductor chips obtained by dividing a semiconductor wafer.

[0019] The "front surface" of a workpiece such as a wafer refers to the surface on which circuits, bumps, and other convex electrodes are formed, while the "back surface" refers to the surface on which circuits, electrodes (for example, bumps and other convex electrodes) are not formed. A protective film is formed on the back surface of the wafer and chip.

[0020] Rework refers to peeling off a protective film-forming film that has been attached to a workpiece for the purpose of attaching another protective film to the workpiece again. Good reworkability of a protective film-forming film refers to the property that allows the protective film-forming film to be peeled off without leaving any protective film remaining on the workpiece.

[0021] Wafer singulation refers to dividing the wafer into individual circuits to obtain chips.

[0022] In this specification, for example, the term "(meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate," and the same applies to other similar terms.

[0023] "Energy rays" refers to ultraviolet rays, electron beams, etc., and is preferably ultraviolet rays.

[0024] The release film is a film that supports the pressure-sensitive adhesive layer or the protective film-forming film in a releasable manner. The term "film" is not limited to a specific thickness, and is used to include a sheet.

[0025] The mass ratios in the descriptions of compositions such as the composition for protective film-forming films are based on the active ingredient (solid content), and do not include the solvent unless otherwise specified.

[0026] (1. Protective film forming film) The protective film-forming film according to this embodiment is attached to a workpiece to form a protective film for protecting the workpiece or a processed product of the workpiece.

[0027] "Protecting" refers to making the protective film-forming film into a state in which it has sufficient properties to protect the workpiece or a processed product of the workpiece. Specifically, when the protective film-forming film according to this embodiment is curable, "making it into a protective film" refers to making the uncured protective film-forming film into a cured product. In other words, the protective film-forming film that has been made into a protective film is a cured product of the protective film-forming film, and is different from the protective film-forming film.

[0028] After the workpiece is superimposed on the curable protective film-forming film, the protective film-forming film is cured, whereby the protective film can be firmly adhered to the workpiece, and a durable protective film can be formed.

[0029] On the other hand, when the protective film-forming film according to this embodiment does not contain a curable component and is used in an uncured state, the protective film-forming film according to this embodiment becomes a protective film when it is attached to a workpiece. In other words, the protective film-forming film that has become a protective film is the same as the protective film-forming film.

[0030] When high protective performance is not required, the protective film-forming film does not need to be cured, and therefore the protective film-forming film is easy to use.

[0031] In addition, it is preferable that the protective film-forming film has adhesiveness at room temperature (23°C) or exhibits adhesiveness when heated. This allows the workpiece to be laminated to the protective film-forming film when it is placed on top of the film. Therefore, positioning can be reliably performed before the protective film-forming film is cured.

[0032] The protective film-forming film may be composed of one layer (single layer) or may be composed of 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 layers constituting these multiple layers is not particularly limited.

[0033] In this embodiment, the protective film-forming film is preferably one layer (single layer). A one-layer protective film-forming film can be easily produced because it can achieve high precision in thickness. Furthermore, if the protective film-forming film is composed of multiple layers, it is necessary to consider the adhesion between the layers and the stretchability of each layer, which may result in the risk of peeling from the adherend. If the protective film-forming film is one layer, the above risks can be reduced and design freedom is increased. Furthermore, the risk of peeling between layers due to differences in thermal stretchability between layers can be reduced in processes where temperature changes occur (during reflow processing or when using the device).

[0034] The thickness of the protective film-forming film is not particularly limited, but is preferably 100 μm or less, 70 μm or less, 45 μm or less, or 30 μm or less. The thickness of the protective film-forming film is preferably 5 μm or more, 10 μm or more, or 15 μm or more. When the thickness of the protective film-forming film is within the above range, the protective performance of the resulting protective film is improved.

[0035] The thickness of the protective film-forming film means the thickness of the entire protective film-forming film. For example, the thickness of a protective film-forming film composed of multiple layers means the total thickness of all layers constituting the protective film-forming film.

[0036] The protective film-forming film according to this embodiment is attached to the back surface of a workpiece to protect it. FIG. 1 shows a workpiece with a protective film-forming film attached to its back surface. A protective film-forming film 10 is attached to the back surface side of the workpiece (the lower side in FIG. 1), and a convex electrode 6b is formed on the front surface side of the workpiece 6 (the upper side in FIG. 1). A circuit is formed on the front surface side of the workpiece 6, and the convex electrode 6b is formed so as to be electrically connected to the circuit.

[0037] When a protective film-forming film is attached to a workpiece, it is usually in the form of a protective film-forming sheet or a protective film-forming composite sheet described below, and after the release film placed on the main surface of the protective film-forming film to protect that main surface is peeled off, one main surface of the protective film-forming film is attached to the back surface of the workpiece.

[0038] After application, the main surface opposite to the main surface in contact with the back surface of the workpiece is often exposed to the outside, particularly in the case of a protective film forming sheet.

[0039] The workpiece to which the protective film-forming film is attached is subjected to an appearance inspection. In this appearance inspection, it is inspected whether or not there is any appearance defect in the protective film-forming film. Specifically, it is inspected whether or not there is any positional deviation, wrinkles, etc. in the attached protective film-forming film. If there is any appearance defect, the protective film-forming film is reworked.

[0040] Incidentally, when the protective film-forming film is curable, the protective film-forming film is softer than the protective film.

[0041] Therefore, if the protective film-forming film is pressed with a laminating roll or the like having small hard foreign matter attached thereto when being applied, or if the protective film-forming film comes into contact with an application device or the like immediately after application, scratches (for example, dents) are likely to occur in the protective film-forming film.

[0042] Furthermore, the protective film-forming film attached to the workpiece may be subjected to another process or transported from one process to another before it is turned into a protective film (for example, cured). Therefore, if the protective film-forming film comes into contact with a device, a transport device, or the like used in another process, the protective film-forming film is also likely to be damaged.

[0043] If such a scratched protective film is used as a protective film, the scratches will be carried over to the protective film, leading to a poor appearance of the protective film, and as a result, the yield of workpieces with protective film (e.g., chips with protective film) will decrease.

[0044] Therefore, even if the protective film-forming film has scratches, it must be judged as a defective appearance of the protective film-forming film in the appearance inspection of the workpiece to which the protective film-forming film is attached.

[0045] If the protective film-forming film is damaged, the damaged protective film-forming film is peeled off from the workpiece and another undamaged protective film-forming film is attached to the workpiece. In other words, the damaged protective film-forming film is reworked. This makes it less likely that the protective film will have poor appearance, and reduces the decrease in chip yield.

[0046] Therefore, even if the protective film-forming film is damaged, it is required to have good reworkability.

[0047] However, when a conventional protective film having scratches is peeled off from a workpiece, the following specific problems arise.

[0048] Fig. 2A is a perspective schematic diagram (Fig. 2A) showing that a scratch 12 has occurred in a conventional protective film-forming film 100 attached to a workpiece 6. Fig. 2B is a cross-sectional schematic diagram (Fig. 2B) taken along line IIB-IIB in Fig. 2A.

[0049] 2B, the scratched portion 12 shown in Fig. 2A is a scratch formed by denting or scraping the surface of the protective film-forming film 100, and is a scratch that does not penetrate the protective film-forming film 100. Therefore, the thickness T1 of the protective film-forming film 100 at the location where the scratch is formed is smaller than the thickness T of the protective film-forming film 100 at the location where the scratch is not formed.

[0050] When peeling off (reworking) the protective film-forming film 100 shown in Figures 2A and 2B, for example, peeling tape is attached to the protective film-forming film 100, and the protective film-forming film 100 is peeled off from the workpiece 6 by pulling the peeling tape in a predetermined direction.

[0051] Fig. 3A is a schematic plan view showing a state immediately after starting to peel off the protective film-forming film 100 from the workpiece 6 to which the protective film-forming film 100 and the peeling tape 30 are attached. Fig. 3B is a schematic cross-sectional view taken along line IIIB-IIIB in Fig. 3A.

[0052] 3A and 3B, the protective film-forming film 100 is peeled off in a predetermined direction (from left to right in FIGS. 3A and 3B). When the peeling interface of the protective film-forming film 100 almost reaches the damaged portion 12, the thickness of the damaged portion 12 is smaller than the thickness of the portion where no damaged portion is formed, and therefore, stress generated inside the protective film-forming film 100 against the peeling is concentrated in the vicinity of the damaged portion 12.

[0053] 3C and 3D, as the peeling progresses further, the vicinity of the scratch portion 12 begins to stretch due to the concentrated stress. On the other hand, in the protective film-forming film 100, other portions where the scratch portion 12 is not formed have a uniform thickness, and therefore, as a result of the peeling, stress is applied to the entire other portions, so that the film is peeled off from the workpiece 6 before the other portions begin to stretch, and the peeling progresses easily. As a result, although the portions other than the scratch portion 12 are peeled off from the workpiece 6, the vicinity of the scratch portion 12 continues to stretch without being peeled off from the workpiece 6.

[0054] When the elongation in the vicinity of the scratch portion 12 reaches its limit, the vicinity of the scratch portion 12 breaks. Then, as shown in FIGS. 3E and 3F, the vicinity of the scratch portion 12 is cut off from the protective film-forming film 100 being peeled off and is left as residue 14 on the workpiece. After the vicinity of the scratch portion 12 is cut off, the protective film-forming film 100 has a uniform overall thickness because the vicinity of the scratch portion 12, which is a portion of different thickness, has been cut off. Therefore, the protective film-forming film 100 is less likely to elongate, and peeling proceeds smoothly.

[0055] In this embodiment, the size of the scratch is, for example, 5 mm or more in length, 10 μm or more in depth t, and the value T1 obtained by subtracting the depth t of the scratch from the thickness T of the protective film-forming film is 5 μm or more. That is, T1=Tt≧5 μm. When such a scratch is formed in the protective film-forming film, residues are likely to be generated when peeled off as described above.

[0056] As described above, when a protective film-forming film on which a scratch has been formed is reworked, peeling off the protective film-forming film results in residue of the protective film-forming film remaining on the workpiece after rework. When the protective film-forming film is reattached to the workpiece, it is necessary to remove the residue, which results in an additional step.

[0057] In contrast, the protective film-forming film of this embodiment has the physical properties described below, so even when reworking a protective film-forming film with a scratched portion, residue is less likely to be generated during rework and damage to the workpiece is suppressed.

[0058] (1.1. Elongation at break in right-angle tear test) In this embodiment, the elongation percentage at break of the protective film-forming film is 200% or less in a right-angle tear test at 23° C. The elongation percentage at break is measured in accordance with JIS K 7128-3:1998. That is, the elongation percentage at break of the protective film-forming film is measured in the same manner as the measurement method (right-angle tear method) specified in JIS K 7128-3:1998, but the measurement conditions may be different.

[0059] The specific measurement method will be explained in the Examples. The test piece has the shape shown in Figure 2 of JIS K 7128-3:1998, and the center of the test piece is recessed at an angle of 90°. The right-angle tear test is performed by pulling both ends of the test piece.

[0060] Therefore, the right-angle tear test is similar to the manner in which stress is applied to the vicinity of a scratch when a protective film-forming film with a scratch formed thereon is peeled off. That is, by having the elongation percentage within the above range, the elongation of the protective film-forming film up to breakage can be reduced when a protective film-forming film with a scratch formed thereon is peeled off. In other words, since a normal tensile test is not similar to the manner in which stress is applied to the vicinity of a scratch, the elongation percentage at break in a normal tensile test is not directly related to the elongation percentage at break in the above-mentioned right-angle tear test.

[0061] As in FIGS. 3A and 3B, when the peeling interface of the protective film-forming film 10 nearly reaches the scratch 12, stress concentrates near the scratch 12. However, in the protective film-forming film 10 according to the present embodiment, even if the protective film-forming film 10 near the scratch 12 begins to stretch, before the stretching becomes significant, fracture originating near the scratch 12 reaches the opposite main surface of the protective film-forming film 10, causing the protective film-forming film 10 near the scratch 12 to break. As shown in FIGS. 4A and 4B, the thickness around the fractured portion is substantially the same as the thickness of other portions, and no stress concentration occurs. Furthermore, the fractured portion is a portion of the protective film-forming film 10 and is not separated from the protective film-forming film 10. As a result, peeling of the protective film-forming film 10 proceeds smoothly without leaving any residue. In other words, even if reworking of the protective film-forming film 10 becomes necessary due to the formation of the scratch 12, the reworkability of the protective film-forming film 10 is good.

[0062] The elongation at break is preferably 150% or less, more preferably 120% or less, and even more preferably 90% or less. The lower the elongation at break, the better, but the lower limit of the elongation at break is, for example, 10%.

[0063] (1.2 Adhesion to silicon wafer) In this embodiment, at 23°C, the adhesive strength to the silicon wafer (hereinafter also referred to as adhesive strength to the silicon wafer) one hour after the protective film-forming film is attached to the #2000 polished surface of the silicon wafer is 20 N / 25 mm or less. The #2000 polished surface is a surface having a surface roughness equivalent to that of a surface polished with a #2000 abrasive. This surface roughness corresponds to the surface roughness of the back surface of a silicon wafer used to manufacture semiconductor chips, etc. Furthermore, after the protective film-forming film is attached to the wafer, a visual inspection of the wafer is performed, and if scratches are formed in the protective film-forming film, the protective film-forming film is reworked. Therefore, by controlling the adhesive strength one hour after attachment rather than immediately after attachment of the protective film-forming film, the protective film-forming film according to this embodiment can be controlled to have characteristics suited to the specific object to which it is attached.

[0064] From the above, by having the adhesive strength to the silicon wafer within the above range, residue is less likely to be generated when the protective film-forming film is peeled off from the workpiece (e.g., wafer), and the load on the workpiece (e.g., wafer) is reduced, thereby reducing damage to the workpiece.

[0065] The adhesive strength to a silicon wafer is preferably 14 N / 25 mm or less, more preferably 9 N / 25 mm or less, and even more preferably 4 N / 25 mm or less. From the viewpoint of reworkability, the lower the adhesive strength to a silicon wafer, the better. However, from the viewpoint of the risk of unintentional peeling in each process after application, the adhesive strength is preferably 0.2 N / 25 mm or more, and more preferably 0.5 N / 25 mm or more.

[0066] The method for measuring adhesion to a silicon wafer is described in the Examples.

[0067] (1.3 Protective Film-Forming Film Composition) As long as the protective film has the above-mentioned physical properties, the composition of the protective film-forming film is not particularly limited. In this embodiment, the composition constituting the protective film-forming film (composition for protective film-forming film) is preferably a resin composition containing at least a polymer component (A), a curable component (B), and a filler (E). The polymer component is a component that can be considered to be formed by a polymerization reaction of a polymerizable compound. Furthermore, the curable component is a component that can undergo a curing (polymerization) reaction. In the present invention, the polymerization reaction also includes a polycondensation reaction.

[0068] In addition, a component contained in the polymer component may also be a curable component. In this embodiment, when the composition for a protective film-forming film contains a component that corresponds to both a polymer component and a curable component, the composition for a protective film-forming film is considered to contain both a polymer component and a curable component.

[0069] 1.3.1 Polymer Components The polymer component (A) provides the protective film-forming film with film-forming properties (film-forming properties) while imparting appropriate tack, ensuring uniform application of the protective film-forming film to the workpiece. The weight-average molecular weight of the polymer component is usually in the range of 50,000 to 2,000,000, preferably 100,000 to 1,500,000, and particularly preferably 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.

[0070] In this specification, unless otherwise specified, the "weight average molecular weight" is a polystyrene equivalent value measured by gel permeation chromatography (GPC). Measurements by such a method can be carried out, for example, using a high-speed GPC apparatus "HLC-8120GPC" manufactured by Tosoh Corporation, with a high-speed column "TSK guard column H" (Figure 1). XL -H", "TSK Gel GMH XL ", "TSK Gel G2000 H XL (All products of Tosoh Corporation) connected in this order are used, and the column temperature is 40°C, the liquid flow rate is 1.0 mL / min, and the detector is a differential refractometer.

[0071] Examples of acrylic resins include (meth)acrylic acid ester copolymers composed of structural units derived from (meth)acrylic acid ester monomers and (meth)acrylic acid derivatives. The (meth)acrylic acid ester monomers are preferably (meth)acrylic acid alkyl esters in which the alkyl group has 1 to 18 carbon atoms, specifically methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, etc. Examples of (meth)acrylic acid derivatives include (meth)acrylic acid, glycidyl (meth)acrylate, hydroxyethyl (meth)acrylate, etc.

[0072] In this embodiment, in order to control the adhesiveness to the workpiece and the adhesive properties, it is preferable to introduce a hydroxyl group into the acrylic resin using hydroxyethyl acrylate or the like.

[0073] The glass transition temperature of the acrylic resin is preferably −70° C. to 40° C., −60° C. to 30° C., −50° C. to 20° C., −40° C. to 15° C., or −30° C. to 10° C. By setting the glass transition temperature of the acrylic resin within the above range, the tack of the protective film-forming film is appropriately increased, and it becomes easier to set the elongation at break in the right-angle tear test within the above range, so that the adhesive strength of the protective film-forming film to the workpiece is within an appropriate range, and the adhesive strength of the protective film to the workpiece is appropriately improved.

[0074] When an acrylic resin has m types of structural units (m is an integer of 2 or more), the glass transition temperature of the acrylic resin can be calculated as follows: That is, when m types of monomers that derive the structural units in the acrylic resin are each sequentially assigned a unique number from 1 to m and named "monomer m," the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox formula shown below.

number

number

[0075] For Tgk, values ​​listed in the Polymer Data Handbook, Adhesive Handbook, or Polymer Handbook can be used. For example, the Tgk of a homopolymer of methyl acrylate is 10°C, that of a homopolymer of n-butyl acrylate is -54°C, that of a homopolymer of methyl methacrylate is 105°C, that of a homopolymer of 2-hydroxyethyl acrylate is -15°C, that of a homopolymer of glycidyl methacrylate is 41°C, that of a homopolymer of 2-ethylhexyl acrylate is -70°C, that of ethyl acrylate is -24°C, and that of 4-hydroxybutyl acrylate is -32°C.

[0076] When the total weight of the composition for the protective film-forming film is 100 parts by mass, the content of the polymer component is preferably 1 to 70 parts by mass, 5 to 60 parts by mass, 10 to 50 parts by mass, or 13 to 40 parts by mass. By setting the content of the polymer component within the above range, it becomes easier to set the elongation at break in a right-angle tear test within the above range. In addition, it becomes easier to control the adhesiveness of the protective film-forming film.

[0077] (1.3.2 Thermosetting components) The curable component (B) cures the protective film-forming film to form a protective film as a cured product. As described above, the curable component can be a thermosetting component, an energy ray-curable component, or a mixture thereof.

[0078] The protective film-forming film according to the present embodiment has a reduced light transmittance because it contains a filler, a colorant, etc., which will be described later. The energy ray-curable protective film-forming film is cured by irradiation with energy rays, and therefore, for example, when the thickness of the protective film-forming film is increased, curing by energy rays tends to be insufficient.

[0079] On the other hand, a thermosetting protective film-forming film can be sufficiently cured by heating even if it is thick, so that a protective film with high protective performance can be formed. Furthermore, by using a conventional heating means such as a heating oven, a large number of protective film-forming films can be heated and thermally cured all at once.

[0080] Therefore, the protective film-forming film according to this embodiment is preferably thermosetting.

[0081] Whether or not 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 above room temperature, and then cooled to room temperature to obtain a protective film-forming film after heating and cooling. Next, when the hardness of the protective film-forming film after heating and cooling is compared with the hardness of the protective film-forming film before heating at the same temperature, if the protective film-forming film after heating and cooling is harder, the protective film-forming film is determined to be thermosetting.

[0082] Preferred examples of thermosetting components include epoxy resins, thermosetting polyimide resins, unsaturated polyester resins, and mixtures thereof. Thermosetting polyimide resins are a general term for low-molecular-weight, low-viscosity monomers or precursor polymers that form polyimide resins by thermal curing. Non-limiting examples of thermosetting polyimide resins are described in, for example, the Sen'i Gakkaishi Journal, "Sen'i to Kogyo," Vol. 50, No. 3 (1994), pp. 106-118.

[0083] Epoxy resins as thermosetting components have the property of undergoing three-dimensional network formation upon heating, forming a strong coating. Various known epoxy resins are used as such epoxy resins. In this 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. The epoxy equivalent of the epoxy resin is preferably 50 to 5,000 g / eq, more preferably 100 to 2,000 g / eq, and even more preferably 150 to 1,000 g / eq.

[0084] 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 alkylglycidyl epoxy resins in which the active hydrogen bonded to the nitrogen atom is substituted with a glycidyl group, such as aniline isocyanurate; and so-called alicyclic epoxides in which epoxy groups are introduced by, for example, oxidizing carbon-carbon double bonds within the molecule, 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. Other epoxy resins that can be used include those having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, and the like.

[0085] When a thermosetting component is used as the curing component (B), it is preferable to use a curing agent (C) as an auxiliary. Heat-activated latent epoxy resin curing agents are preferred as curing agents for epoxy resins. A "heat-activated latent epoxy resin curing agent" is a type of curing agent that is difficult to react with epoxy resins at room temperature (23°C) but becomes activated and reacts with epoxy resins when heated above a certain temperature. Activation methods for heat-activated latent epoxy resin curing agents include generating active species (anions and cations) through a chemical reaction caused by heating; stably dispersing the curing agent in the epoxy resin at room temperature and becoming compatible and dissolved with the epoxy resin at high temperatures to initiate the curing reaction; using a molecular sieve-encapsulated curing agent that dissolves at high temperatures to initiate the curing reaction; and using microcapsules.

[0086] Of the methods exemplified above, a method in which the compound is stably dispersed in the epoxy resin at around room temperature, becomes compatible and dissolved with the epoxy resin at high temperatures, and initiates a curing reaction is preferred.

[0087] 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 such as imidazole compounds. These heat-activated latent epoxy resin curing agents can be used alone or in combination of two or more. In this embodiment, dicyandiamide is particularly preferred.

[0088] Phenol resins are also preferred as curing agents for epoxy resins. Examples of phenolic resins that can be used include, but are not limited to, condensates of phenols such as alkylphenols, polyphenols, and naphthol with aldehydes. Specific examples include phenol novolac resins, o-cresol novolac resins, p-cresol novolac resins, t-butylphenol novolac resins, dicyclopentadiene cresol resins, polyparavinylphenol resins, bisphenol A novolac resins, and modified versions of these resins.

[0089] The phenolic hydroxyl groups contained in these phenolic resins can easily undergo addition reaction with the epoxy groups of the epoxy resins by heating to form a cured product with high impact resistance.

[0090] The content of the curing agent (C) is preferably 0.2 to 100 parts by mass, 0.5 to 50 parts by mass, 1 to 20 parts by mass, or 1.5 to 10 parts by mass relative to 100 parts by mass of the epoxy resin. By setting the content of the curing agent (C) within the above range, the network structure of the protective film becomes dense, making it easier to obtain the protective film's ability to protect the workpiece, and making it easier to set the elongation at break in a right-angle tear test within the above range.

[0091] When dicyandiamide is used as the curing agent (C), it is preferable to use a curing accelerator (D) in combination. Examples of the curing accelerator 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.

[0092] The content of the curing accelerator is preferably 0.1 to 10 parts by mass, 0.3 to 5 parts by mass, 0.5 to 4 parts by mass, or 1 to 3 parts by mass relative to 100 parts by mass of the epoxy resin. By setting the content of the curing accelerator (D) within the above range, the network structure of the protective film becomes dense, making it easier to obtain the protective film's ability to protect the workpiece, and making it easier to set the elongation at break in a right-angle tear test within the above range.

[0093] When the total weight of the composition for protective film-forming films is 100 parts by mass, the total content of the thermosetting component and the curing agent is preferably 3 to 80 parts by mass, 5 to 60 parts by mass, 7 to 50 parts by mass, 9 to 40 parts by mass, or 10 to 30 parts by mass. By setting the total content of the thermosetting component and the curing agent to be equal to or greater than the above lower limit, the composition exhibits appropriate tack before curing, allowing stable application. After curing, the composition is likely to provide the ability to protect the workpiece as a protective film. By adjusting the degree of curing by setting the total content of the thermosetting component and the curing agent within the above range, it becomes easier to set the elongation at break in a right-angle tear test within the above range.

[0094] (1.3.3 Energy ray curable component) When the curable component (B) is an energy ray-curable component, the energy ray-curable component is preferably uncured and has adhesive properties, and more preferably uncured and has adhesive properties.

[0095] The energy ray curable component is a component that is cured by irradiation with energy rays, and is also a component that imparts film-forming properties, flexibility, and the like to the protective film-forming film.

[0096] The energy ray-curable component is preferably, for example, a compound having an energy ray-curable group, and examples of such compounds include known compounds.

[0097] (1.3.4 Filler) By including the filler (E) in the protective film-forming film, the protective film obtained by converting the protective film-forming film into a protective film can easily have its thermal expansion coefficient adjusted, and by making this thermal expansion coefficient closer to the thermal expansion coefficient of the workpiece, the adhesive reliability of the protective film-equipped chip obtained using the protective film-forming film is further improved. Furthermore, by including the filler (E) in the protective film-forming film, a hard protective film can be obtained, and the moisture absorption rate of the protective film can be reduced, further improving the adhesive reliability of the protective film-equipped chip.

[0098] The filler (E) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler from the viewpoint of shape stability at high temperatures.

[0099] Preferred inorganic fillers include, for example, powders of silica, alumina, talc, calcium carbonate, red iron oxide, silicon carbide, boron nitride, etc.; beads of these inorganic fillers that have been spherically formed; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; glass fibers, etc. Among these, silica and surface-modified silica are preferred. The surface-modified silica is preferably surface-modified with a coupling agent, more preferably surface-modified with a silane coupling agent.

[0100] The average particle size of the filler is preferably 0.05 to 10 μm, 0.07 to 3 μm, or 0.09 to 1 μm.

[0101] In addition, in this embodiment, it is preferable that two or more types of fillers with different average particle diameters are contained. By containing fillers with different average particle diameters in the protective film-forming film, fillers with smaller average particle diameters are more likely to be arranged in the gaps between fillers with larger average particle diameters. As a result, it becomes easier to keep the elongation at break in the right-angle tear test within the above range. Furthermore, when two or more types of fillers with different average particle diameters are contained, the average particle diameter of the filler with the largest average particle diameter is preferably 1 μm or less, 0.7 μm or less, or 0.5 μm or less.

[0102] In particular, it is preferable that the average particle size of the filler having the largest average particle size is 1.5 to 10 times the average particle size of the filler having the smallest average particle size.

[0103] In this specification, unless otherwise specified, the term "average particle size" refers to the particle size (D50) at an integrated value of 50% in a particle size distribution curve determined by a laser diffraction scattering method.

[0104] When the total weight of the composition for a protective film-forming film is taken as 100 parts by mass, the content of the filler is preferably 10 to 80 parts by mass, 25 to 75 parts by mass, 40 to 70 parts by mass, or 56 to 70 parts by mass.

[0105] By setting the lower limit of the filler content to the above value, the adhesive reliability of the protective film-coated chip obtained using the protective film-forming film is further improved, and it becomes easier to keep the elongation at break in the right-angle tear test within the above range. Also, by setting the upper limit of the filler content to the above value, the adhesive strength of the protective film-forming film to the workpiece is improved, and the adhesive strength of the protective film to the workpiece is appropriately improved.

[0106] 1.3.5 Coupling Agents The protective film-forming film preferably contains a coupling agent (F). By containing the coupling agent, after the protective film-forming film is cured, the adhesion between the protective film and the workpiece can be improved without impairing the heat resistance of the protective film, and the water resistance (moist heat resistance) can be improved. As the coupling agent, a silane coupling agent is preferred from the viewpoint of its versatility and cost benefits.

[0107] Examples of silane coupling agents 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)tetrasulfane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazole silane. Preferred silane coupling agents include oligomeric silane coupling agents having multiple alkoxysilyl groups per molecule. The oligomeric silane coupling agents are preferred because they are less likely to volatilize and have multiple alkoxysilyl groups per molecule, making them effective in improving durability. Examples of the oligomeric silane coupling agents include epoxy group-containing oligomeric silane coupling agents such as "X-41-1053," "X-41-1059A," "X-41-1056," and "X-40-2651" (all manufactured by Shin-Etsu Chemical Co., Ltd.); and mercapto group-containing oligomeric silane coupling agents such as "X-41-1818," "X-41-1810," and "X-41-1805" (all manufactured by Shin-Etsu Chemical Co., Ltd.). These agents can be used alone or in combination.

[0108] When the total weight of the composition for a protective film-forming film is taken as 100 parts by mass, the content of the coupling agent is preferably 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, or 0.3 to 3 parts by mass.

[0109] (1.3.6 Colorants) The protective film-forming film preferably contains a colorant (G), which conceals the back surface of the workpiece such as a chip, thereby blocking various electromagnetic waves generated in electronic devices and reducing malfunction of the workpiece such as a chip.

[0110] As the colorant (G), for example, known colorants such as organic pigments, organic dyes, inorganic pigments, etc. In this embodiment, inorganic pigments are preferred.

[0111] Examples of inorganic pigments include carbon black, cobalt-based pigments, iron-based pigments, chromium-based pigments, titanium-based pigments, vanadium-based pigments, zirconium-based pigments, molybdenum-based pigments, ruthenium-based pigments, platinum-based pigments, ITO (indium tin oxide)-based pigments, and ATO (antimony tin oxide)-based pigments. Among these, carbon black is particularly preferred. Carbon black can block electromagnetic waves over a wide wavelength range.

[0112] The amount of colorant (especially carbon black) in the protective film-forming film varies depending on the thickness of the protective film-forming film, but for example, when the thickness of the protective film-forming film is 25 μm, the content of the colorant is preferably 0.01 to 10 parts by mass, 0.03 to 7 parts by mass, or 0.05 to 4 parts by mass when the total weight of the composition for the protective film-forming film is 100 parts by mass.

[0113] The average particle size of the colorant (particularly carbon black) is preferably 1 to 500 nm, 3 to 100 nm, or 5 to 50 nm. When the average particle size of the colorant is within the above range, it is easy to control the light transmittance within a desired range.

[0114] (1.3.7 Other additives) The composition for the protective film-forming film may contain other additives, such as a photopolymerization initiator, a crosslinking agent, a plasticizer, an antistatic agent, an antioxidant, a gettering agent, a tackifier, a release agent, etc., within the range that does not impair the effects of the present invention.

[0115] (2. Protective film forming sheet) The sheet for forming a protective film according to this embodiment includes the above-mentioned protective film-forming film and a release film disposed on at least one main surface of the protective film-forming film. The release film is peeled off when the protective film-forming film is used.

[0116] The protective film forming sheet 50 shown in Figure 5 has a configuration in which a first release film 21 supporting the protective film forming film 10 is arranged on one main surface 10a of the protective film forming film 10, and a second release film 22 is arranged on the other main surface 10b.

[0117] The protective film forming sheet of this embodiment is used to form a protective film on the workpiece or a processed product of the workpiece by attaching a protective film forming film to the workpiece when processing the workpiece, turning the protective film forming film into a protective film.

[0118] The protective film-forming sheet may be in the form of a long sheet whose longitudinal length is very long relative to its lateral length, or in the form of a sheet roll obtained by winding up such a long sheet.

[0119] Furthermore, the protective film forming sheet may be a protective film forming sheet that has been punched so that the protective film forming film to be attached to the workpiece has a predetermined closed shape. The predetermined closed shape is not particularly limited, but it is preferably approximately the same shape as the workpiece to be attached.

[0120] (2.1 Release film) The release film is a film that can releasably support the protective film-forming film. The release film may be composed of one layer (single layer) or two or more layers of substrate, and the surface of the substrate may be subjected to a release treatment in order to control the releasability. That is, the surface of the substrate may be modified, or a material (release agent layer) not derived from the substrate may be formed on the surface of the substrate.

[0121] The substrate is not particularly limited as long as it is a material that can support the protective film-forming film until it is attached to the workpiece, and is usually composed of a film whose main component is a resin-based material (hereinafter referred to as a "resin film").

[0122] Specific examples of resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester copolymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these films may also be used. Furthermore, laminated films of these films may also be used. In this embodiment, polyethylene terephthalate films are preferred from the standpoints of environmental safety, cost, and the like.

[0123] The resin film may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler.

[0124] The release agent layer is obtained by applying a coating agent containing a composition for a release agent layer to one surface of a substrate, and then drying and curing the coating. The composition for a release agent layer is not particularly limited as long as it is a material that can impart releasability from the protective film-forming film to the substrate. In this embodiment, the composition for a release agent layer is preferably, for example, an alkyd-based release agent, a silicone-based release agent, a fluorine-based release agent, an unsaturated polyester-based release agent, a polyolefin-based release agent, or a wax-based release agent, and among these, a silicone-based release agent is preferred.

[0125] The thickness of the release film is not particularly limited, but is preferably 15 to 100 μm, more preferably 25 to 80 μm, and even more preferably 35 to 60 μm.

[0126] In the sheet for forming a protective film shown in FIG. 5, it is preferable that the release strength of one release film is made large to be a heavy release type release film, and the release strength of the other release film is made small to be a light release type release film.

[0127] (3. Composite sheet for forming protective film) The composite sheet for forming a protective film according to this embodiment includes the above-described protective film-forming film and a support sheet that supports the protective film-forming film. The configuration of the support sheet is not particularly limited as long as it can control the adhesion and releasability sufficient to obtain a workpiece with a protective film. For example, the support sheet may consist only of a substrate having a predetermined rigidity, as described below. In this embodiment, in order to more easily control the adhesion and releasability, the support sheet is preferably an adhesive sheet having a substrate and an adhesive layer.

[0128] 6 has a configuration including an adhesive sheet 4 formed by laminating an adhesive layer 42 on one surface of a substrate 41, a protective film-forming film 10 laminated on the adhesive layer 42 side of the adhesive sheet 4, and a jig adhesive layer 5 laminated on the peripheral edge of the protective film-forming film 10. In other words, the adhesive sheet 4 is a support sheet. The jig adhesive layer 5 is a layer for adhering the composite sheet 60 for forming a protective film to a jig such as a ring frame.

[0129] The composite sheet for forming a protective film according to this embodiment is attached to a workpiece when the workpiece is processed to hold the workpiece, and is also used to turn a protective film-forming film into a protective film and form a protective film on the workpiece or a processed product of the workpiece.

[0130] Specifically, it is used to hold a wafer as a workpiece during dicing processing of the wafer, and to form a protective film on chips as the processed product obtained by dicing, but is not limited to this.

[0131] (3.1. Adhesive sheet) The adhesive sheet 4 of the composite sheet for forming a protective film according to this embodiment is configured to include a substrate 41 and an adhesive layer 42 laminated on one surface of the substrate 41.

[0132] (3.1.1. Base material) The base material of the adhesive sheet is not particularly limited as long as it is suitable for processing the workpiece, such as dicing and expanding a wafer, and is usually composed of a film whose main component is a resin-based material (hereinafter referred to as a "resin film").

[0133] Specific examples of resin films include polyethylene films such as low-density polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, and high-density polyethylene (HDPE) film; polyolefin films such as polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; ethylene copolymer films such as ethylene-vinyl acetate copolymer film, ethylene-(meth)acrylic acid copolymer film, and ethylene-(meth)acrylic acid ester copolymer film; polyvinyl chloride films such as polyvinyl chloride copolymer film; polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin films. Modified films such as crosslinked films and ionomer films can also be used. The substrate 41 may be a film made of one of these materials, or a laminate film made by combining two or more of these materials. In this embodiment, polypropylene film and polybutylene terephthalate film are preferred from the viewpoint of heat resistance when the composite sheet for forming a protective film is used in a process in which it is heated.

[0134] The resin film may be subjected to a surface treatment such as oxidation or roughening, or a primer treatment, on one or both sides as desired, in order to improve adhesion to the pressure-sensitive adhesive layer 42 laminated on its surface. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment, while examples of the roughening method include sandblasting and thermal spray treatment.

[0135] The resin film may contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler.

[0136] The thickness of the substrate 41 is not particularly limited as long as the composite sheet for forming a protective film can function appropriately in each process in which it is used, and is preferably in the range of 20 to 200 μm, more preferably 40 to 170 μm, and particularly preferably 50 to 140 μm.

[0137] (3.1.2. Adhesive Layer) The adhesive layer of the adhesive sheet of the composite sheet for forming a protective film according to this embodiment may be composed of a non-energy ray-curable adhesive or an energy ray-curable adhesive. Non-energy ray-curable adhesives preferably have the desired adhesive strength and removability, and examples of such adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, acrylic adhesives are preferred because they have high adhesion to the protective film-forming film and can effectively prevent the workpiece or processed workpiece from falling off during a dicing process or the like. Acrylic adhesives are also preferred because they facilitate control of the pick-up suitability of chips with protective films.

[0138] On the other hand, the adhesive strength of energy ray-curable adhesives decreases when irradiated with energy rays, so when it is desired to separate the workpiece or a processed product of the workpiece from the adhesive sheet, they can be easily separated by irradiating them with energy rays.

[0139] The energy ray-curable adhesive constituting the adhesive layer may be one whose main component is a polymer having energy ray curability, or one whose main component is a mixture of a polymer not having energy ray curability and an energy ray-curable monomer and / or oligomer.

[0140] Examples of energy ray-curable polymers include (meth)acrylic acid ester (co)polymers into which energy ray-curable groups have been introduced. Examples of energy ray-curable monomers and / or oligomers include esters of polyhydric alcohols and (meth)acrylic acid. The energy ray-curable adhesive may also contain additives such as photopolymerization initiators and crosslinking agents in addition to the energy ray-curable components.

[0141] The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as it can function appropriately in each process in which the composite sheet for forming a protective film is used. Specifically, the thickness of the pressure-sensitive adhesive layer is preferably 1 to 50 μm, 2 to 30 μm, 2 to 20 μm, 3 to 10 μm, or 3 to 8 μm.

[0142] The adhesive constituting the jig adhesive layer is preferably one having the desired adhesive strength and removability, and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among these, acrylic adhesives are preferred because they have high adhesion to jigs such as ring frames and can effectively prevent the composite sheet for forming a protective film from peeling from the ring frame during dicing processes, etc. A substrate serving as a core material may be interposed in the thickness direction of the jig adhesive layer.

[0143] The thickness of the pressure-sensitive adhesive layer for jigs is preferably 5 to 200 μm, particularly preferably 10 to 100 μm, from the viewpoint of adhesiveness to jigs such as ring frames.

[0144] (4. Method for producing protective film-forming film and protective film-forming sheet) The method for producing the protective film-forming film is not particularly limited. The film is produced using the above-mentioned composition for the protective film-forming film, or a composition obtained by diluting the composition for the protective film-forming film with a solvent (these two compositions are referred to as "coating agent"). The coating agent is prepared by mixing the components constituting the composition for the protective film-forming film by a known method.

[0145] The obtained 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, bar coater, gravure coater, curtain coater, etc., and dried as necessary to form a protective film-forming film on the first release film.

[0146] Next, the release surface of a second release film is further laminated to the exposed surface of the protective film-forming film formed on the first release film, thereby obtaining the sheet for forming a protective film shown in FIG.

[0147] (5. Method for manufacturing composite sheet for forming protective film) The method for producing the composite sheet for forming a protective film is not particularly limited. For example, the composite sheet for forming a protective film can be produced by separately producing a first laminate including a protective film-forming film and a second laminate including a pressure-sensitive adhesive sheet as a support sheet, and then laminating the protective film-forming film and the pressure-sensitive adhesive sheet using the first laminate and the second laminate.

[0148] The first laminate can be produced by the same method as the above-mentioned sheet for forming a protective film. That is, a protective film-forming film is formed on the release surface of the first release film, and the release surface of the second release film is bonded to the exposed surface of the protective film-forming film.

[0149] On the other hand, to produce the second laminate, first, a pressure-sensitive adhesive composition that will form the pressure-sensitive adhesive layer, or a composition obtained by diluting the pressure-sensitive adhesive composition with a solvent (these two compositions are referred to as "coating agents"). Next, the coating agent is applied to the release surface of a third release film and dried as necessary to form a pressure-sensitive adhesive layer on the third release film. After that, a substrate is attached to the exposed surface of the pressure-sensitive adhesive layer, and a laminate (second laminate) consisting of a pressure-sensitive adhesive sheet made of the substrate and pressure-sensitive adhesive layer and the third release film is obtained.

[0150] Here, when the pressure-sensitive adhesive layer is made of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer may be cured by irradiating it with energy rays at this stage, or the pressure-sensitive adhesive layer may be cured after laminating it with the protective film-forming film. Furthermore, when the pressure-sensitive adhesive layer is cured after laminating it with the protective film-forming film, the pressure-sensitive adhesive layer may be cured before the dicing step, or the pressure-sensitive adhesive layer may be cured after the dicing step.

[0151] As the energy beam, ultraviolet rays, electron beams, etc. are usually used. The irradiation dose of the energy beam varies depending on the type of energy beam. For example, in the case of ultraviolet rays, the light dose is 50 to 1000 mJ / cm. 2 is preferred, and particularly 100 to 500 mJ / cm 2 In the case of electron beams, the intensity is preferably about 10 to 1000 krad.

[0152] Once the first laminate and the second laminate are obtained in the above manner, the second release film of the first laminate is peeled off, and the third release film of the second laminate is peeled off, and the protective film-forming film exposed in the first laminate is bonded to the adhesive layer of the adhesive sheet exposed in the second laminate.

[0153] In this way, a composite sheet for forming a protective film is obtained, which comprises an adhesive sheet having an adhesive layer laminated on a substrate, a protective film-forming film laminated on the adhesive layer side of the adhesive sheet, and a first release film laminated on the protective film-forming film on the side opposite the adhesive sheet. If necessary, after peeling off the first release film, a jig adhesive layer is formed on the peripheral portion of the exposed adhesive layer.

[0154] (6. Rework method and device manufacturing method) A rework method and a manufacturing method of an apparatus using a protective film-forming film according to the present embodiment will be described. As an example of a manufacturing method of an apparatus, a method of obtaining a workpiece with a protective film by dividing a workpiece to which a protective film-forming film is attached will be described.

[0155] The rework method according to this embodiment includes at least the following steps 1 to 3. The device manufacturing method according to this embodiment includes at least the following steps 1 to 6. That is, the rework method according to this embodiment and the device manufacturing method according to this embodiment overlap with each other in steps 1 to 3. Step 1: Applying the protective film to the back of the workpiece Step 2: Inspecting the appearance of the applied protective film Step 3: If scratches are found on the protective film applied in step 2, this is the step of peeling off the damaged protective film from the workpiece. Process 4: A process of attaching the above protective film to the backside of the workpiece, separate from the protective film that was peeled off from the workpiece. Process 5: A process of forming a protective film on the protective film to obtain a workpiece with a protective film. Step 6: A step of processing the workpiece with the protective film to obtain a workpiece with the protective film.

[0156] A rework method including the above steps 1 to 3 and a device manufacturing method including the above steps 1 to 6 will be described with reference to FIGS. 7A, 7B, and 8. FIG.

[0157] 7A, the protective film-forming film 10 of the protective film-forming sheet 50 is attached to the back surface of the wafer 6 as a workpiece (step 1). If necessary, the first release film 21 may be peeled off.

[0158] 7B, the protective film-forming film 10 of the composite sheet 60 for forming a protective film is attached to a wafer 6 as a workpiece (step 1). At this time, the outer periphery of the protective film-forming film 10 may be fixed by a ring frame 7. In this embodiment, as shown in FIG. 6, a jig adhesive layer 5 is provided on the outer periphery of the protective film-forming film 10, and therefore the jig adhesive layer 5 is attached to the ring frame 7. The wafer 6 is attached to the surface of the protective film-forming film 10 opposite to the surface attached to the adhesive layer 42. When attaching the protective film-forming film 10 to the wafer 6, the protective film-forming film 10 may be heated, if desired, to exhibit adhesiveness.

[0159] Next, the appearance of the attached protective film-forming film is inspected (step 2). It is possible to proceed directly from step 1 to step 2, or to proceed from step 1 to step 2 via another step. The method for inspecting the appearance of the protective film-forming film is not particularly limited as long as it is a method that can detect whether or not scratches have been formed in the protective film-forming film. For example, it may be an inspection in which the appearance of the protective film-forming film is visually confirmed, an inspection in which an image of the protective film-forming film acquired using an imaging device equipped with a predetermined optical system is visually confirmed, an inspection in which the image is processed using image processing software or an image processing processor, or the like, and an inspection in which the appearance is confirmed by irradiating it with light having a predetermined wavelength and analyzing the transmitted light or reflected light.

[0160] In step 2, if no scratches are found in the protective film-forming film, the workpiece to which the protective film-forming film is attached is transported to the next step.

[0161] On the other hand, if a scratch is found in the protective film-forming film, the protective film-forming film is reworked from the workpiece to which it is attached (step 3). In step 3, when the protective film-forming film of the protective film-forming composite sheet is attached to the workpiece, first, the support sheet (adhesive sheet) arranged on the side opposite to the side on which the protective film-forming film is attached to the workpiece is peeled off from the protective film-forming film, exposing the protective film to the outside. Next, a peeling tape is attached to the surface of the protective film-forming film on which the scratch has been formed. The peeling tape is a sheet having a base material and an adhesive layer. By pulling the peeling tape at a predetermined angle, the protective film-forming film follows the peeling tape, and the protective film-forming film is peeled off (reworked) from the workpiece together with the peeling tape.

[0162] At this time, since the protective film-forming film has the above-described physical properties, even if a scratch is formed, no residue of the protective film-forming film remains on the workpiece after peeling. That is, the protective film-forming film is reworked well. Furthermore, since the protective film-forming film is peeled well without requiring a large peeling force, damage to the workpiece caused by the application of a strong force can be suppressed.

[0163] As described above, the rework method is established by going through steps 1 to 3.

[0164] Next, a description will be given of a device manufacturing method having steps 1 to 6. In the device manufacturing method, steps 1 to 3 are the same as steps 1 to 3 in the rework method, so a description of steps 1 to 3 will be omitted.

[0165] When the protective film forming film is reworked, there is no protective film forming film on the back surface of the workpiece. Therefore, a protective film forming film different from the reworked protective film forming film is attached to the back surface of the workpiece (step 4).

[0166] After application, as described above, it is necessary to inspect whether or not scratches have been formed on the protective film-forming film, and if scratches have been formed, the protective film-forming film may be reworked.

[0167] When no scratches are formed on the protective film-forming film, the protective film-forming film is converted into a protective film to form the protective film 1, thereby obtaining a workpiece with a protective film (step 5). When the protective film-forming film is curable, an operation for curing the protective film-forming film may be performed. For example, when the protective film-forming film is thermosetting, the protective film-forming film 10 may be heated at a predetermined temperature for an appropriate time. For example, the heating temperature is preferably 100 to 200°C, and may be, for example, either 110 to 180°C or 120 to 170°C. The heating time is preferably 0.5 to 5 hours, and may be, for example, either 0.5 to 3 hours or 1 to 2 hours. Furthermore, when the protective film-forming film 10 is energy ray-curable, energy rays may be incident from the pressure-sensitive adhesive sheet 4 or the release film side. For example, the irradiance of the energy rays may be 120 to 280 mW / cm. 2 The energy ray dose is 100-1000mJ / cm 2 It is preferable that:

[0168] Next, the workpiece with the protective film is processed (step 6). An example of the process of processing the workpiece with the protective film is a process of dividing the workpiece with the protective film to obtain a predetermined number of workpieces with the protective film. When the workpiece is a wafer and the workpieces are chips, as shown in FIG. 8, the wafer with the protective film held by dicing tape 22 can be diced to obtain chips 70 with the protective film. Also, in step 6, when the wafer with the protective film is obtained using a composite sheet for forming a protective film, the wafer with the protective film held by the support sheet can be diced to obtain chips with the protective film. As the dicing method, a known dicing method can be used. The obtained chips 70 with the protective film are picked up and recovered by a suction collet or the like.

[0169] The picked-up chips with protective film may be transported to the next process, or may be temporarily stored in a tray, tape, or the like, and then transported to the next process after a predetermined period of time.

[0170] The protective film-coated chip 70 is transported to the next process and mounted on a substrate, thereby manufacturing a semiconductor device.

[0171] (7. Variations) A release film may be laminated on the surface of the protective film-forming composite sheet 60 on the protective film-forming film 10 side in order to protect the protective film-forming film until use.

[0172] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and may be modified in various ways within the scope of the present invention. [Example]

[0173] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0174] (Preparation of protective film forming sheet) A sheet for forming a protective film was prepared as follows using a coating agent containing the composition for forming a protective film described below.

[0175] (Coating agent containing a composition for a protective film-forming film) The following components were mixed in the blending ratio (solid content equivalent) shown in Table 1 and diluted with methyl ethyl ketone to a solid content concentration of 50 mass % to prepare a coating agent containing a composition for a protective film-forming film. (A) Polymer component (A-1): (meth)acrylic acid ester copolymer obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of ethyl acrylate, 10 parts by mass of methyl acrylate, and 10 parts by mass of 4-hydroxybutyl acrylate (weight average molecular weight: 600,000, glass transition temperature: -25°C) (A-2): (meth)acrylic acid ester copolymer obtained by copolymerizing 10 parts by mass of ethyl acrylate, 5 parts by mass of methyl methacrylate, 75 parts by mass of methyl acrylate, and 10 parts by mass of 4-hydroxybutyl acrylate (weight average molecular weight: 500,000, glass transition temperature: 1°C) (B) Curing component (thermosetting component) (B-1) Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184-194 g / eq) (B-2) Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, jER1055, epoxy equivalent 800-900 g / eq) (B-3) Dicyclopentadiene type epoxy resin (Dainippon Ink and Chemicals, Inc., Epicron HP-7200HH, softening point 88-98°C, epoxy equivalent 274-286g / eq) (C) Curing agent: dicyandiamide (ADEKA Corporation, ADEKA Hardener EH-3636AS, heat-activated latent epoxy resin curing agent, active hydrogen content 21 g / eq) (D) Curing accelerator: 2-phenyl-4,5-dihydroxymethylimidazole (Curesol 2PHZ, manufactured by Shikoku Chemicals Corporation) (E) Filler (E-1) Silica filler (manufactured by Admatechs Co., Ltd., SC2050-MNU, average particle size 0.5 μm) (E-2) Silica filler (manufactured by Admatechs Co., Ltd., SC1050-MLQ, average particle size 0.3 μm) (E-3) Silica filler (manufactured by Admatechs Co., Ltd., Y100SV-CM1, average particle size 0.1 μm) (F) Coupling agent (F-1): 3-glycidyloxypropyltrimethoxysilane (Shinyetsu Silicones Co., Ltd., KBM403) (F-2): Oligomeric silane coupling agent containing epoxy groups, methyl groups, and methoxy groups (Shin-Etsu Silicones, X-41-1056, epoxy equivalent 280 g / eq) (G) Colorant: Carbon black (Mitsubishi Chemical Corporation, MA-600B, average particle size 28 nm)

[0176] A first release film (SP-PET502150, manufactured by Lintec Corporation) was prepared, which consisted of a 50 μm-thick polyethylene terephthalate (PET) film with a silicone-based release agent layer formed on one side. Also, a second release film (SP-PET381031, manufactured by Lintec Corporation) was prepared, which consisted of a 38 μm-thick polyethylene terephthalate (PET) film with a silicone-based release agent layer formed on one side.

[0177] The coating agent containing the prepared protective film-forming film composition was applied to the release-treated surface of a first release film and dried at 100°C for 2 minutes to form a protective film-forming film with a thickness of 25 μm. Subsequently, a second release film was attached to the protective film-forming film to obtain a three-layered sheet for protective film formation in which release films were laminated on both sides of the protective film-forming film. The attachment conditions for the second release film were a temperature of 60°C, a pressure of 0.4 MPa, and a speed of 1 m / min.

[0178] The obtained sheet for forming a protective film was subjected to the following measurements and evaluations.

[0179] (Elongation rate at break of protective film-forming film in right-angle tear test) The second release films of the two protective film-forming sheets obtained were peeled off, and the exposed surfaces of the protective film-forming films (the surfaces on which the first release film was not formed) were attached to each other. One of the first release films was peeled off to obtain a laminate in which two protective film-forming films were laminated to the other first release film. Furthermore, the exposed surface of the protective film-forming film from which the second release film was peeled off from another protective film-forming sheet was attached to the exposed surface of the protective film-forming film of the laminate in which two protective film-forming films were laminated to the first release film, and the first release film of the other protective film-forming sheet was peeled off. This was repeated six times to laminate a total of eight protective film-forming films, producing a laminate in which the first release film, a protective film-forming film having a thickness of 200 μm, and the first release film were laminated in this order.

[0180] If the protective film-forming film is 25 μm thick, the thickness of the laminated protective film-forming film is preferably 200 μm, but if the protective film-forming film is not 25 μm thick, the number of laminations is selected appropriately, and the thickness of the laminated protective film-forming film is preferably 180 to 220 μm.

[0181] The resulting laminate in which the first release films were laminated on both surfaces of the laminated protective film-forming film was punched out using a super dumbbell cutter (manufactured by Dumbbell Co., Ltd., SDBK-1000) to the dimensions of a rectangular tear test specimen as specified in JIS K 7128-3: 1998. The shape of the rectangular tear test specimen was the shape shown in Figure 2 of JIS K 7128-3: 1998.

[0182] The first release films on both surfaces of the obtained rectangular tear test specimen were removed, and a rectangular tear test was carried out using a universal tensile tester (AG-IS, manufactured by Shimadzu Corporation) at a test temperature of 23° C. In the rectangular tear test, the test length (distance between chucks) of the rectangular tear test specimen before the test was set to 60 mm, and the tensile speed was set to 200 mm / min.

[0183] The elongation (%) at break at 23°C was calculated from the elongation of the test piece at break, ΔL, starting from the point at which tension was started, using the following formula. The results are shown in Table 1. Elongation at break = (ΔL / test length of rectangular tear test piece before test (60 mm)) × 100

[0184] (Adhesion strength of protective film to silicon wafer) In the obtained sheet for forming a protective film, an adhesive tape (Adwill D-841 manufactured by Lintec Corporation) consisting of a substrate and an adhesive layer was attached to the exposed surface of the protective film-forming film (the surface on which the first release film was not formed) after peeling off the second release film. Then, using an ultraviolet irradiation device, an illuminance of 230 mW / cm was applied. 2 , light intensity 190mJ / cm 2The adhesive tape was irradiated with ultraviolet light under the conditions of (a) to cure the adhesive tape to the extent that peeling between the protective film-forming film and the adhesive tape did not occur. The obtained laminate was cut into a size of 25 mm x 140 mm to prepare a test piece.

[0185] In addition, when the protective film-forming film is energy ray curable, the protective film-forming film will be cured, so a test piece of adhesive tape that has not been irradiated with ultraviolet rays is used for measurement.

[0186] Next, the first release film was peeled off from the obtained test piece, and the exposed surface of the protective film-forming film was attached to the #2000 polished surface of a silicon wafer having a thickness of 500 μm and an outer diameter of 6 inches using a laminator device (TAISEI LAMINATOR CO., LTD., VA-400 model). At this time, the conditions were: roller temperature 70°C, attachment speed 0.3 m / min, attachment pressure 0.3 MPa. Thereafter, the test piece was left to stand for 1 hour in an environment of 23°C and relative humidity 50%.

[0187] Next, under conditions of 23°C, a precision universal testing machine (Shimadzu Corporation, Autograph AG-IS) was used to peel the laminate of the protective film-forming film and adhesive tape from the silicon wafer at a peeling speed of 300 mm / min. At this time, a so-called 180° peel was performed, in which the surfaces that had been in contact with the protective film-forming film and the silicon wafer formed an angle of 180°. The peel force (N / 25 mm) at this time was measured, and this measured value was taken as the adhesive force of the protective film-forming film to the silicon wafer. The results are shown in Table 1.

[0188] (Rework Test) The exposed surface of a protective film-forming film of a protective film-forming sheet cut to the same shape as the silicon wafer was attached to the back surface (#2000 polished surface) of a workpiece consisting of a silicon wafer with a thickness of 300 μm and an outer diameter of 8 inches using an attachment device (RAD-3600F / 12, manufactured by Lintec Corporation) at 70°C. Then, in order to reproduce a protective film-forming film that had been scratched during or after attachment, a linear scratch 10 mm long and 12 μm deep was created in the protective film-forming film. The position and orientation of the linear scratch were as shown in scratch portion 12 in Figure 4A. Next, at 23°C, the release film was peeled off, and an adhesive tape (Adwill D-841, manufactured by Lintec Corporation) consisting of a substrate and an adhesive layer was attached as a peeling tape to the exposed surface of the protective film-forming film. Then, using an ultraviolet irradiation device, an illuminance of 230 mW / cm was applied. 2 , light intensity 190mJ / cm 2 The adhesive tape was irradiated with ultraviolet light under the conditions of (a) and (b) to harden the adhesive tape to such an extent that peeling between the protective film-forming film and the adhesive tape did not occur.

[0189] The silicon wafer with the protective film-forming film and adhesive tape attached was fixed to a suction table, and the laminate of the protective film-forming film and adhesive tape was peeled off from the silicon wafer at a peeling speed of 300 mm / min. At this time, a so-called 180° peel was performed, in which the surfaces of the protective film-forming film and the silicon wafer that had been in contact with each other formed an angle of 180°.

[0190] The protective film-forming films of the examples and comparative examples were subjected to the above-mentioned rework test 10 times and evaluated according to the following evaluation criteria. The results are shown in Table 1. Excellent: Of the 10 wafers that underwent the rework test, the protective film was peeled off from 9 or more wafers without leaving any residue. Good: Of the 10 wafers that underwent the rework test, the protective film was peeled off from 6 to 8 wafers without leaving any residue. Unacceptable: Of the 10 wafers that underwent the rework test, the protective film was peeled off from 5 or fewer wafers without leaving any residue.

[0191] [Table 1]

[0192] From Table 1, it was confirmed that when the elongation rate at break in the right-angle tear test of the protective film-forming film and the adhesive strength to the silicon wafer are within the above-mentioned ranges, no residue is generated during rework and it is good. On the other hand, it was confirmed that when the elongation rate at break in the right-angle tear test of the protective film-forming film is outside the above-mentioned ranges, residue is likely to be generated during rework. [Explanation of symbols]

[0193] 10, 100...Protective film forming film 50...Protective film forming sheet 10...Protective film forming film 21...First release film 22...Second release film 60...Composite sheet for forming protective film 10...Protective film forming film 4...Adhesive sheet 70...Chip with protective film 1…Protective film

Claims

1. A protective film-forming film for forming a protective film, The protective film-forming film has an elongation of 120% or less at 23°C when broken in a right-angle tear test, A protective film-forming film in which the protective film-forming film is attached to the #2000 polished surface of a silicon wafer, and then left to stand for 1 hour in an environment of 23°C and 50% relative humidity, and then the protective film-forming film is peeled off from the silicon wafer at an angle of 180° at a peeling speed of 300 mm / min, and the adhesive strength of the protective film-forming film is 9 N / 25 mm or less at 23°C.

2. The protective film-forming film according to claim 1 , which is heat-curable or energy ray-curable.

3. A sheet for forming a protective film, comprising: the protective film-forming film according to claim 1 or 2; and a release film releasably disposed on at least one main surface of the protective film-forming film.

4. A composite sheet for forming a protective film, comprising: the protective film-forming film according to claim 1 or 2; and a support sheet that supports the protective film-forming film.

5. A step of attaching the protective film-forming film according to claim 1 or 2 to a back surface of a workpiece; A step of inspecting the appearance of the attached protective film-forming film; This rework method includes a step of inspecting the appearance of the applied protective film-forming film, and if a scratch is found in the applied protective film-forming film, a step of peeling off the damaged protective film-forming film from the workpiece.

6. A step of attaching the protective film-forming film according to claim 1 or 2 to a back surface of a workpiece; A step of inspecting the appearance of the attached protective film-forming film; a step of peeling off the damaged protective film-forming film from the workpiece when a scratch is found on the attached protective film-forming film in a step of inspecting the appearance of the attached protective film-forming film; A step of attaching the protective film-forming film according to claim 1 or 2, which is separate from the protective film-forming film peeled off from the workpiece, to the back surface of the workpiece; a step of forming the protective film-forming film into a protective film to obtain a workpiece with a protective film; and a step of processing the workpiece with the protective film to obtain a workpiece with the protective film.

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