Method of manufacturing device having workpiece with protective film

Abstract

To provide a method of manufacturing a device having a workpiece with a protective film capable of easily determining whether or not an arrival temperature of the workpiece with the protective film in a reflow process is a temperature at which a convex electrode is sufficiently melted.SOLUTION: A step 1 of attaching a protection membrane-forming film to a rear surface of a workpiece having a front surface provided with a convex electrode and a rear surface, a step 2 of obtaining a workpiece with a protection membrane by forming the protection membrane-forming film into a protection membrane, a step 3 of performing laser marking on the front surface of the protection membrane, a step 4 of obtaining a workpiece product with a protection membrane by dividing the workpiece with a protection membrane into individual pieces, a step 5 of disposing the workpiece product with a protection membrane on a substrate, and a reflow step 6 of melting the convex electrode by heating the workpiece product with a protection membrane after steps 3 and 5, when a line width of the marking before the reflow process is A and a line width of the marking after the reflow process is B, A is 20 μm or more and a change amount (B-A) of the line width is 5 μm or more.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a device having a protectively coated workpiece. [Background technology]

[0002] Semiconductor chips are obtained as workpieces by dividing a workpiece such as a wafer on which a circuit is formed. In recent years, semiconductor devices have been manufactured using a mounting method called flip-chip bonding, which uses semiconductor chips having circuit surfaces on which convex electrodes such as bumps are formed. In this mounting method, when mounting the semiconductor chip, the circuit surface of the semiconductor chip is inverted (face down) and bonded to the chip mounting section. This results in a structure in which the back side of the semiconductor chip, on which no circuit is formed, is exposed.

[0003] For this reason, a hard protective film made of an organic material is often formed on the back side of the semiconductor chip to protect the semiconductor chip from shocks during transportation, etc. The protective film is formed, for example, by applying a protective film-forming film to the back side of the semiconductor wafer and then curing it. To identify the semiconductor chip, the surface of such a protective film is marked with letters, marks, etc., by, for example, laser marking. In such laser marking, laser light is incident on the surface of the protective film to change the surface condition of the protective film, and marking is performed by contrast with the unchanged portion.

[0004] The semiconductor chip with the protective film formed thereon is placed on the circuit surface of the substrate as an electronic component. Then, in order to improve the electrical and mechanical connectivity between the semiconductor chip and the circuit surface of the substrate, the semiconductor chip with the protective film formed thereon is heated in a reflow furnace to melt the convex electrodes formed on the semiconductor chip, thereby firmly bonding and fixing the semiconductor chip to the substrate. This process is called the reflow process.

[0005] Patent Document 1 describes a protective film-forming film for forming a protective film on the backside of a chip. It describes that this protective film-forming film can be restored to a state where it can be reattached when peeled off from the backside of a wafer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-146565 Summary of the Invention [Problem to be solved by the invention]

[0007] In the reflow process, the heating temperature and holding time are controlled to ensure that the convex electrodes are melted. However, in an actual reflow furnace, variations in temperature distribution can occur, and for some semiconductor chips subjected to the reflow process, the maximum temperature of the semiconductor chip may not reach the temperature at which the convex electrodes are sufficiently melted, and the reflow process may end. In this case, the bonding between the semiconductor chip and the substrate is insufficient, and such products are judged to be defective.

[0008] Whether or not the bonding between the semiconductor chip and the substrate is insufficient can be evaluated by using a light transmission type image inspection, an electrical inspection, etc. after the reflow process. However, these inspection methods have the problem of lacking in convenience.

[0009] The present invention has been made in consideration of the above-described circumstances, and aims to provide a method for manufacturing a device having a workpiece with a protective film, which makes it easy to determine whether the temperature reached by the workpiece with a protective film during the reflow process is a temperature at which the convex electrode is sufficiently melted. [Means for solving the problem]

[0010] The aspects of the present invention are as follows.

[0011] [1] A step of attaching a protective film-forming film to the back surface of a workpiece having a surface on which a convex electrode is formed and a back surface opposite to the front surface; A step of forming the attached protective film-forming film into a protective film to obtain a workpiece with a protective film; a marking step of performing laser marking on the protective film to form a marking on the surface of the protective film; A step of singulating the protective film-coated workpiece to obtain a plurality of protective film-coated workpieces; a placement step of placing the protective film-covered workpiece on a substrate; a reflow process for heating the workpiece with the protective film using a reflow furnace to melt the convex electrodes after the marking process and the arranging process; This is a method for manufacturing a device having a workpiece with a protective film, in which, when the line width of the marking before the reflow process is A and the line width of the marking after the reflow process is B, A is 20 μm or more and (BA), which indicates the amount of change in line width, is 5 μm or more.

[0012] [2] A method for manufacturing a device having a workpiece with a protective film according to [1], wherein the temperature of the workpiece with a protective film is 265°C or higher for a total of 30 seconds or more during the reflow process.

[0013] [3] A method for manufacturing a device having a workpiece with a protective film according to [1] or [2], in which the line width change rate (100×(BA) / A) is 10% or more.

[0014] [4] A method for manufacturing a device having a workpiece with a protective film according to any one of [1] to [3], wherein B is 40 μm or more. [Effects of the Invention]

[0015] According to the present invention, a method for manufacturing a device having a workpiece with a protective film can be provided, which makes it easy to determine whether the temperature reached by the workpiece with a protective film during the reflow process is a temperature at which the convex electrode is sufficiently melted. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional schematic diagram of an example of a sheet for forming a protective film provided with a protective film-forming film. [Figure 2] FIG. 2 is a cross-sectional schematic diagram of an example of a composite sheet for forming a protective film provided with a protective film-forming film. [Figure 3A] FIG. 3A is a schematic cross-sectional view illustrating a step of attaching a protective film-forming film included in a protective film-forming sheet to a wafer. [Figure 3B] FIG. 3B is a cross-sectional view illustrating a process of attaching the protective film-forming film included in the composite sheet for forming a protective film to a wafer. [Figure 4] FIG. 4 is a schematic plan view of the surface of the protective film after laser marking. [Figure 5] FIG. 5 is a schematic cross-sectional view of an example of a chip with a protective film. [Figure 6] FIG. 6 is a schematic cross-sectional view of an example of an apparatus having a chip 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 refers to a plate-shaped body to which a protective film-forming film (described later) is attached and then singulated. The protective film-forming film is attached to the back surface of the workpiece. Examples of workpieces include circular wafers (including those having an orientation flat), rectangular panel-level packages, and strips (rectangular substrates) sealed with molded resin. Among these, wafers made of inorganic materials are preferred from the viewpoint of easily achieving the effects of the present invention. Examples of wafers include semiconductor wafers such as silicon wafers, gallium arsenide wafers, silicon carbide wafers, gallium nitride wafers, and indium phosphide wafers, as well as insulator wafers such as glass wafers, lithium tantalate wafers, and lithium niobate wafers. They may also be reconstructed wafers made of a resin and a semiconductor used in the manufacture of fan-out packages, etc. From the viewpoint of easily achieving the effects of the present invention, semiconductor wafers or insulator wafers are preferred.

[0019] Singulation of a workpiece refers to dividing the workpiece into individual circuits to obtain workpieces. For example, if the workpiece is a wafer, the workpiece is a chip, and if the workpiece is a panel-level package or a strip (rectangular substrate) sealed with molded resin, the workpiece is a semiconductor package.

[0020] The "front surface" of a workpiece refers to the surface on which a circuit or the like is formed or is planned to be formed. On the front surface, convex electrodes (bump electrodes, pillar electrodes, etc.) are also formed. The "back surface" of a workpiece refers to the surface on which no circuit or the like is formed or is not planned to be formed.

[0021] The term "main surface" refers to a surface that is larger in area than the other surfaces of a plate-like body. A plate-like body usually has two main surfaces and other side surfaces, and the two main surfaces face each other. In a workpiece, the "front surface" and the "back surface" are the main surfaces.

[0022] The term "(meth)acrylate" is used to refer to both "acrylate" and "methacrylate," and similar terms.

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

[0024] Unless otherwise specified, "weight-average molecular weight" is a polystyrene-equivalent value measured by gel permeation chromatography (GPC). Measurements using this method are performed using, for example, a Tosoh high-speed GPC system (HLC-8120GPC) connected in this order with high-speed columns (TSK guard column HXL-H, TSK Gel GMHXL, and TSK Gel G2000 HXL) at a column temperature of 40°C and a flow rate of 1.0 mL / min, using a differential refractometer as the detector.

[0025] The release film is a film that supports 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.

[0026] The mass ratios in the descriptions of compositions such as the composition for the protective film-forming film are based on the active ingredient (solid content), and do not include the solvent unless otherwise specified.

[0027] (1. Method for manufacturing a device having a workpiece with a protective film) In this embodiment, the protective film-equipped workpiece is obtained by dividing a workpiece having a convex electrode formed on its front surface and a protective film formed on its back surface. An example of such a protective film-equipped workpiece is a chip with a protective film. When the protective film-equipped chip is mounted on a substrate by flip-chip bonding, a process of arranging the chip so that the convex electrode formed on its front surface contacts the circuit surface of the substrate (arrangement process) is performed. Then, a process of melting the convex electrode (reflow process) is performed to bond the chip and the substrate, and a device is manufactured in which the protective film-equipped chip is mounted on the substrate.

[0028] In the reflow process, the temperature inside the reflow furnace is controlled so that it reaches a temperature at which the convex electrodes are sufficiently melted. However, since the reflow process is performed while transporting a large number of chips into the reflow furnace, the temperature reached by some chips may not reach a temperature at which the convex electrodes are sufficiently melted.

[0029] If the temperature does not reach a temperature at which the convex electrode is sufficiently melted, the bond between the chip and the substrate will be insufficient. Therefore, such products must be screened as defective. However, conventional inspections (such as optical transmission imaging inspections and electrical inspections) require specialized inspection equipment and take a long time, making it difficult to easily determine whether the bond is insufficient.

[0030] Therefore, the present inventors have discovered a method for easily evaluating whether the temperature of the convex electrode has reached a sufficient melting temperature during the reflow process by utilizing markings on the protective film that are typically applied to workpieces with a protective film in order to identify the workpiece. Specifically, the inventors have discovered that the line width of the marking changes before and after the reflow process, and by setting the amount of change in line width within a predetermined range, they have discovered a method for easily evaluating by visual inspection whether the temperature of the convex electrode has reached a sufficient melting temperature. Below, a detailed description is given of a method for manufacturing a device having a workpiece with a protective film according to this embodiment.

[0031] The method for manufacturing a device having a workpiece with a protective film according to this embodiment includes at least the following steps 1 to 6. Step 1: A step of attaching a protective film to the back surface of a workpiece having a surface on which a convex electrode is formed and a back surface opposite to the front surface. Process 2: The process of forming the protective film on the attached protective film to obtain a workpiece with a protective film. Step 3: A marking step in which laser marking is performed on the protective film to form a marking on the surface of the protective film. Step 4: A step of dividing the workpiece with the protective film into individual pieces to obtain a plurality of workpieces with the protective film. Step 5: Placement step of placing the workpiece with the protective film on the substrate Step 6: After the marking and placement steps, a reflow process is performed in which the workpiece with the protective film is heated in a reflow furnace to melt the convex electrodes.

[0032] Step 4 can be performed after step 2 and before step 5.

[0033] In the following, a description will be given of a method for manufacturing an apparatus having a workpiece with a protective film, which includes the above-mentioned steps 1 to 6, in which the workpiece is a wafer having a convex electrode formed on its surface, and the workpiece is a chip.

[0034] (1.1.Process 1) In step 1, a protective film-forming film is attached to the back surface of the wafer. The protective film-forming film will be described later. The protective film-forming film is usually used in the form of a protective film-forming sheet or a protective film-forming composite sheet including the protective film-forming film.

[0035] The protective film-forming sheet 10 has the configuration shown in Fig. 1. The protective film-forming film 1 has two opposing main surfaces 1a and 1b. A first release film 21 that supports the protective film-forming film 1 is disposed on the main surface 1a, and a second release film 22 that supports the protective film-forming film 10 is disposed on the main surface 1b.

[0036] When release films are formed on both main surfaces of the protective film-forming film as shown in Figure 1, it is preferable to increase the release strength of one release film to make it a heavy release type release film, and to decrease the release strength of the other release film to make it a light release type release film.

[0037] The protective film forming sheet is preferably a long sheet capable of forming a plurality of protective film forming films to be attached to the workpiece. The protective film forming sheet is also preferably a sheet roll obtained by winding up the long sheet. The protective film forming sheet may also be a single sheet obtained by cutting the long protective film forming sheet to form a single protective film forming film to be attached to the workpiece. The protective film forming sheet may also be configured to not have either the first release film or the second release film.

[0038] The composite sheet for forming a protective film has a protective film-forming film and a support sheet that supports the protective film-forming film. The support sheet is other than a release film and has a configuration that can support the protective film-forming film. An example of the support sheet is a pressure-sensitive adhesive sheet having a substrate and a pressure-sensitive adhesive layer.

[0039] Specifically, as shown in Fig. 2, the composite sheet 11 for forming a protective film has a configuration including an adhesive sheet 40 formed by laminating an adhesive layer 42 on one surface of a substrate 41 as a support sheet, a protective film-forming film 1 laminated so that its main surface 1b is in contact with the adhesive layer 42 of the adhesive sheet 40, and a release film 23 arranged on the main surface 1a of the protective film-forming film 1. Furthermore, a jig adhesive layer (not shown) may be arranged on the peripheral edge of the protective film-forming film 1. The jig adhesive layer is a layer for adhering the composite sheet for forming a protective film to a jig such as a ring frame.

[0040] It is preferable that first release film 21, second release film 22, and release film 23 are all release films formed by forming a silicone-based release agent layer on one side of a polyethylene terephthalate (PET) film. The base material 41 of adhesive sheet 40 is not particularly limited as long as it is suitable for processing the workpiece, and examples of its constituent material include a polypropylene film or a polybutylene terephthalate film having a thickness of 50 to 140 μm. Adhesive layer 42 has a thickness of, for example, 3 to 15 μm, and its constituent material is not particularly limited, and examples thereof include an acrylic non-energy ray curable adhesive or an energy ray curable adhesive.

[0041] When using a protective film-forming sheet, as shown in Fig. 3A, the protective film-forming film 1 of the protective film-forming sheet 10 from which the second release film 22 has been removed is attached to the back surface of the wafer 100. The first release film 21 may be peeled off as needed after step 1.

[0042] Furthermore, when a protective film-forming composite sheet is used, as shown in FIG. 3B , the protective film-forming film 1 of the protective film-forming composite sheet 11 is attached to the back surface of the wafer 100. At this time, the jig adhesive layer 50 provided on the outer periphery of the protective film-forming film 1 may be attached and fixed to a ring frame 150. The surface of the protective film-forming film 1 opposite to the surface in contact with the adhesive layer 42 is attached to the back surface of the wafer 100. When attaching the protective film-forming film 1 to the wafer 100, the protective film-forming film 1 may be heated, if desired, to exhibit adhesiveness.

[0043] (1.2.Process 2) In step 2, the attached protective film-forming film 1 is converted into a protective film to form a protective film, thereby obtaining a wafer with a protective film. If the protective film-forming film is thermosetting, the protective film is formed by heating the protective film-forming film at a predetermined temperature for an appropriate time to harden it. If the protective film-forming film is energy ray-hardenable, the protective film is formed by irradiating it with energy rays from the adhesive sheet or release film side to harden it. If the protective film-forming film is non-hardenable, the protective film is formed when it is attached to the backside of the wafer in step 1.

[0044] (1.3.Step 3) In step 3, laser marking is performed on the protective film. Laser marking is performed by printing a product number or the like on the surface of the protective film to enhance the identifiability of the chip with the protective film. Laser marking is performed by irradiating the protective film with laser light having a predetermined wavelength, for example by scraping off or modifying the irradiated portion, thereby causing a change in the surface condition between the irradiated portion and the non-irradiated portion, thereby performing marking. Any marking that is identifiable can be used, and examples of such marking include letters, numbers, symbols, marks, and figures.

[0045] In this embodiment, the laser marking is performed before the reflow process described below, and the line width of the marking by the laser marking is wider after the reflow process than before. That is, if the line width of the marking before the reflow process is A and the line width of the marking after the reflow process is B, the change in line width (B-A) is 5 μm or more. Note that line width A is the narrowest line width of the markings.

[0046] Since the change in line width before and after the reflow process is within the above range, it is possible to visually observe the surface of the protective film and recognize that the line width has widened after the reflow process. Therefore, it is possible to confirm from the change in line width of the marking that the protective film has been sufficiently heated in the reflow process, that the convex electrodes present near the protective film have been reliably melted, and that a strong bond has been formed. This makes it possible to easily confirm the quality of the bond without having to observe the bonded portion, which is difficult to check.

[0047] From the viewpoint of ensuring visual recognition, the amount of change in line width (BA) may be 10 μm or more, 15 μm or more, or 20 μm or more.

[0048] It is also preferable that the rate of change in line width calculated from line widths A and B (100 × (BA) / A) is 10% or more. When the rate of change is within the above range, the quality of the bonding state can be easily confirmed, similar to the amount of change in line width.

[0049] From the viewpoint of ensuring visual recognition, the rate of change in line width (100×(BA) / A) may be 15% or more, 22% or more, or 30% or more.

[0050] From the viewpoint of distinguishability of the marking, the line width A of the marking before the reflow process is 20 μm or more. The line width A may be 25 μm or more, 30 μm or more, or 35 μm or more.

[0051] Furthermore, from the viewpoint of the distinguishability of the marking, the line width B of the marking after the reflow process may be 40 μm or more, 45 μm or more, 50 μm or more, or 55 μm or more.

[0052] The area on the surface of the protective film where the marking is made is not particularly limited. In this embodiment, it is preferable that the marking is present at least near the periphery in the planar region of the protective film. Specifically, it is preferable that the distance D from the periphery of the protective film to the marking is 1500 μm or less. Note that the chip with the protective film usually has a rectangular shape in a planar view. When the chip with the protective film is rectangular, as shown in FIG. 4, it is preferable that the distances D1, D2, D3, and D4 from the four vertices of the protective film 2 of the chip with the protective film to the marking (letter A) are all 1500 μm or less. As a result, the marking is present throughout the planar region of the protective film near the periphery, making it easy to confirm that the predetermined temperature has been reached, even near the periphery of the planar region of the protective film.

[0053] Therefore, it is possible to easily check whether the temperature of the chip has reached the melting point of not only the convex electrodes located near the center but also the convex electrodes located near the periphery. The larger the area of ​​the chip in plan view, the greater the variation in the temperature of the protective film due to the variation in the temperature in the reflow furnace. Therefore, in this embodiment, the area of ​​the chip in plan view is set to 25 mm 2 If so, it is preferable that the area where marking is performed satisfies the above conditions.

[0054] There are no particular limitations on the laser marker device that can achieve a line width change within the above range, but for laser marking that can easily achieve a line width change within the above range, it is preferable to use a laser marker device that uses a UV (ultraviolet) light source, which has a short wavelength and relatively high light energy, among the light sources that can be used for laser marker devices. A laser marker device that uses a UV light source can irradiate laser light with a wavelength of 355 nm, for example.

[0055] As for laser marking conditions, when using a laser marker device with a UV light source, the frequency of the laser light (Q-switch frequency) may be 10 kHz to 90 kHz, 20 kHz to 80 kHz, or 30 kHz to 70 kHz, and the output of the laser light may be 0.1 W to 0.9 W, 0.2 W to 0.8 W, or 0.25 W to 0.7 W.

[0056] The scanning speed of the laser light is preferably different when the laser light is irradiated directly onto the protective film and when it is irradiated through another sheet, etc. (transmitting through another sheet, etc.). For example, when marking is performed by converting the protective film-forming film included in the protective film-forming sheet into a protective film, the laser light is directly irradiated onto the protective film. In this case, if the scanning speed of the laser light is excessively reduced, the laser light traveling straight through the protective film may be irradiated for too long, which may cause damage to the wafer or chip. On the other hand, when marking is performed by converting the protective film-forming film included in the protective film-forming composite sheet into a protective film, the laser light passes through the support sheet included in the protective film-forming composite sheet and is irradiated onto the protective film. At this time, when the laser light passes through the support sheet, as described below, in addition to the straight-traveling laser light, weak diffused transmitted light is generated. By utilizing such weak diffused transmitted light, the amount of change in line width may be increased. When the laser light is irradiated onto the protective film after passing through the support sheet, it is preferable to relatively reduce the scanning speed of the laser light in order to extend the time during which the diffused transmitted light is irradiated onto the protective film and make effective use of it, compared to when the laser light is irradiated directly onto the protective film.

[0057] Therefore, when a protective film is directly irradiated with laser light using a protective film-forming sheet, the scanning speed of the laser light may be 100 mm / sec or more and 500 mm / sec or less, 150 mm / sec or more and 400 mm / sec or less, or 200 mm / sec or more and 350 mm / sec or less. When a protective film is irradiated with laser light that has passed through a support sheet using a protective film-forming composite sheet, the scanning speed of the laser light may be 30 mm / sec or more and 250 mm / sec or less, 70 mm / sec or more and 200 mm / sec or less, or 90 mm / sec or more and 150 mm / sec or less.

[0058] The mechanism by which the line width of the marking by laser marking changes before and after the reflow process can be exemplified as follows.

[0059] When a protective film is irradiated with laser light for laser marking, the colorant present in the protective film is damaged by the energy, which is thought to cause changes in the properties and physical characteristics of the colorant.

[0060] When a protective film is directly irradiated with laser light traveling straight through air, the colorant α present in the direction of the laser light is damaged by the intense light energy (light damage) and by the thermal energy (thermal damage). Meanwhile, after entering the protective film, a portion of the laser light is scattered within the protective film, slightly diverging from its direction of travel. Although light energy reaches the region where the laser light has diverged, its intensity is weak, suggesting that the colorant β present in that region tends to suffer less thermal damage. Furthermore, colorant α present in the direction of the laser light and colorant γ other than colorant β present in the region where the laser light has diverged are not damaged by the energy of the laser light. Furthermore, because the laser light diverges and begins to travel within the protective film after entering the protective film, colorant β present in the region where the laser light has diverged is present inside the protective film, not on its surface. Therefore, on the surface of the protective film, colorant α present in the direction of the laser light and undamaged colorant γ are present, and the contrast difference between the two is thought to be observed as the line width A of the marking.

[0061] When the marked chip with the protective film is subsequently subjected to a reflow process, heat energy is applied to the entire protective film due to heating in the reflow furnace, causing thermal damage to the protective film. Therefore, the colorant β present in the area where the laser light spreads is likely to suffer thermal damage in addition to the optical damage it already suffered. Furthermore, the colorant β' that has suffered both optical and thermal damage is likely to segregate on the surface of the protective film due to the increased mobility of the colorant β' within the protective film due to the high temperature. As a result, the colorant α present in the direct direction of the laser light and the colorant β present in the area where the laser light spreads tend to be thermally damaged and present on the surface of the protective film. As a result, the colorant that has suffered both optical and thermal damage is more widely distributed on the surface of the protective film after the reflow process than before, resulting in a wider line width for the marking. As a result, the line width change (BA) and change rate (100 × (BA) / A) are likely to increase.

[0062] When laser light is irradiated onto a protective film through another sheet (e.g., a support sheet), after entering the other sheet, some of the laser light is scattered slightly from its straight-line direction and travels through the other sheet. Because the intensity of the laser light passing through the other sheet and entering the protective film is weakened in the straight-line direction, the colorant α present in the straight-line direction of the laser light is subject to both optical and thermal damage, even though the region is relatively shallow in the depth direction of the protective film. Furthermore, in this embodiment, as described above, the scanning speed of the laser light is reduced to extend the time during which the diffused transmitted light irradiates the protective film, compared to when the laser light is directly irradiated onto the protective film. As a result, in the region where the laser light is spread by the other sheet, the weak light does not travel in the depth direction of the protective film, and the colorant β present in the region where the laser light is spread is susceptible to optical damage, even though the region is relatively shallow.

[0063] Therefore, it is thought that the contrast difference between colorant α, which has been damaged by both light and heat, and colorant β, which has been damaged by light but not by heat, and colorant γ, which has not been damaged, is observed visually as the line width A of the marking.

[0064] When the marking-applied chip with the protective film is subsequently subjected to a reflow process, the entire protective film is thermally damaged. Therefore, the light-damaged colorant β is also thermally damaged, becoming colorant β', which is thought to tend to reside on the surface of the protective film. As a result, the contrast difference between colorant α and colorant β', which have both light and heat damage, and colorant γ, which has only been thermally damaged, is thought to be observed as the marking line width B. As a result, the line width change amount (BA) and change rate (100 × (BA) / A) are thought to be large.

[0065] In contrast, when irradiating the protective film with laser light through another sheet or the like without reducing the scanning speed of the laser light, the colorant β in the area where the laser light spreads receives little light energy, and therefore is thought to suffer very little light damage. In other words, the colorant β is thought to be similar to the undamaged colorant γ. Therefore, even after the reflow process, the colorant β in the area where the laser light spreads is thermally damaged but not light-damaged. Therefore, the contrast difference between the colorant α, which has been damaged both by light and heat, and the colorants β and γ, which have been thermally damaged but not light-damaged, is thought to be observed as the line width B of the marking. As a result, the line width change (BA) and change rate (100 × (BA) / A) are thought to be small.

[0066] (1.4.Step 4) In step 4, the protective film-coated wafer is diced into individual pieces to obtain multiple protective film-coated chips. When a protective film-forming sheet is used, an example of the dicing method is to attach a known dicing sheet to the protective film-coated wafer and a ring frame, and then dice the protective film-coated wafer using a known dicing device. When a protective film-forming composite sheet is used, an example is to use a support sheet as a dicing sheet and dice the protective film-coated wafer using a known dicing device. By dicing, multiple protective film-coated chips are obtained.

[0067] As shown in Figure 5, the chip 101 with a protective film has a protective film 2 formed on the back side (upper side in Figure 5) of the chip 101a, and a convex electrode 101b formed on the front side (lower side in Figure 5) of the chip 101a.

[0068] A circuit is formed on the surface of the chip 101a, and the convex electrodes 101b are formed to be electrically connected to the circuit. Examples of the convex electrodes 101b include bumps and pillar electrodes.

[0069] (1.5.Step 5) In step 5, the surface of the protective film-coated chip on which the convex electrodes are formed is placed facing the circuit surface of the substrate so that the convex electrodes come into contact with the connection pads on the circuit surface of the substrate.

[0070] (1.6.Step 6) In step 6, the protective film-coated chip is heated using a reflow furnace. By heating the protective film-coated chip using a reflow furnace, the convex electrodes melt and are electrically and mechanically bonded to the connection pads. This step is called the reflow step. As a result, as shown in FIG. 6, the protective film-coated chip 101 is mounted on the substrate 200 together with another chip 102, and a device 300 including the protective film-coated chip 101 is obtained.

[0071] In the reflow process, a substrate on which a protective film-coated chip is placed is transported at a predetermined speed by a conveyor or the like through a known reflow furnace, and the protective film-coated chip is heated by a heater to a temperature at which the convex electrodes melt. The reflow furnace is usually divided into multiple zones with predetermined temperature profiles, taking into consideration the melting of the convex electrodes and damage to the substrate and other components due to heating.

[0072] Although the protective film-coated chips are heated according to a set temperature profile, variations in temperature can occur in the actual furnace, and some protective film-coated chips may not be heated to a temperature at which the convex electrodes melt. In this case, the bonding between the convex electrodes and the connection pads is insufficient. Protective film-coated chips with insufficient bonding are screened out as defective products through inspection, but testing for insufficient bonding between the convex electrodes and the connection pads (such as optical transmission imaging testing or electrical testing) requires time-consuming specialized testing equipment, making it difficult to easily determine whether the bonding is insufficient.

[0073] In this embodiment, as described above, the laser marking on the protective film is performed so that the change in line width of the marking before and after the reflow process is 5 μm or more. Therefore, in the reflow process, when the chip with the protective film is heated to a temperature at which the convex electrode melts, the change in line width is 5 μm or more. As a result, an observer can indirectly check the bonding state between the convex electrode and the connection pad by observing the marking on the protective film after the reflow process and determining whether the line width has widened. If the change in line width is 5 μm or more, it is easy to visually recognize that the line width has widened compared to before the reflow process, so it is possible to accurately check whether the bonding between the convex electrode and the connection pad is insufficient.

[0074] In the reflow process, it is preferable that the temperature of the protective film-coated chip be 265° C. or higher for a total of 30 seconds or more. By keeping the temperature and heating time of the protective film-coated chip within the above ranges, the convex electrodes are reliably melted, and the bonding state between the convex electrodes and the connection pads can be confirmed more accurately by observing the change in line width.

[0075] (2. Protective film forming film) As described above, the protective film-forming film is attached to the workpiece, and then becomes a protective film to form a protective film, thereby protecting the workpiece or the processed workpiece.

[0076] "Protecting" refers to making the protective film-forming film into a state in which it has sufficient properties to protect the workpiece or the processed 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] In this embodiment, the protective film-forming film is preferably curable. Therefore, the protective film is preferably a cured product. Examples of the cured product include a thermosetting product and an energy ray-cured product. In this embodiment, the protective film is more preferably a thermosetting product.

[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] 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.

[0083] 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.

[0084] 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 terms of 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 the degree of freedom in design is increased.

[0085] The thickness of the protective film-forming film may be less than 50 μm, may be 40 μm or less, or may be 30 μm or less. The thickness of the protective film-forming film may be 3 μm or more, 5 μm or more, 10 μm or more, or 15 μm or more.

[0086] 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.

[0087] (2.1. Composition for Protective Film-Forming Film) A known composition can be adopted as the composition of the protective film-forming film. 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. 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.

[0088] 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.

[0089] 2.1.1 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. If the weight-average molecular weight is too low, the peeling force of the release film may be excessively increased. On the other hand, if the weight-average molecular weight is too high, compatibility with other components may be poor, resulting in the prevention of uniform film formation. Examples of such polymer components include acrylic resins, urethane resins, phenoxy resins, silicone resins, and saturated polyester resins, with acrylic resins being particularly preferred.

[0090] 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.

[0091] In this embodiment, it is preferable to introduce a glycidyl group into the acrylic resin using glycidyl methacrylate or the like. The compatibility of the acrylic resin into which the glycidyl group has been introduced with the epoxy resin as the thermosetting component described below is improved, making it easier to form a uniform film, and there is a tendency to more easily obtain a protective film-forming film with stable performance. Furthermore, in this embodiment, it is preferable to introduce a hydroxyl group into the acrylic resin using hydroxyethyl acrylate or the like in order to control the adhesion to the workpiece and the adhesive properties.

[0092] The glass transition temperature of the acrylic resin is preferably −70 to 40° C., −35 to 35° C., −20 to 30° C., −10 to 25° C., or −5 to 20° C. By setting the glass transition temperature of the acrylic resin within the above range, it becomes easier to adjust the peel strength of the release film laminated on the protective film-forming film to a desired value. Furthermore, by setting the upper limit of the glass transition temperature of the acrylic resin to the above value, the tack of the protective film-forming film is appropriately increased, and the adhesive strength of the protective film-forming film to the workpiece is improved, thereby appropriately improving the adhesive strength of the protective film to the workpiece.

[0093] 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.

[0094]

number

[0095] (In the formula, Tg is the glass transition temperature of the acrylic resin; m is an integer of 2 or greater; Tgk is the glass transition temperature of a homopolymer of monomer m; and Wk is the mass fraction of structural unit m derived from monomer m in the acrylic resin, with the proviso that Wk satisfies the following formula.)

[0096]

number

[0097] (In the formula, m and Wk are the same as above.)

[0098] 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, and the Tgk of a homopolymer of 2-hydroxyethyl acrylate is -15°C.

[0099] When the total weight of the composition for the protective film-forming film (i.e., the mass of the protective film-forming film) is taken as 100 parts by mass, the content of the polymer component may be 5 to 50 parts by mass, 10 to 40 parts by mass, 15 to 35 parts by mass, or 20 to 30 parts by mass. By setting the content of the polymer component within the above range, the protective film-forming film is given film-forming properties (film-forming properties) while also being given appropriate tack, making it easier to adjust the suitability for attachment of the protective film-forming film to the workpiece.

[0100] (2.1.2. Thermosetting component) The curable component (B) cures the protective film-forming film to form a hard protective film. As the curable component, a thermosetting component, an energy ray-curable component, or a mixture thereof can be used. As described above, the protective film-forming film is preferably thermosetting, and therefore the curable component is preferably a thermosetting component.

[0101] Preferred examples of thermosetting components include epoxy resins, thermosetting polyimide resins, unsaturated polyester resins, and mixtures thereof. Thermosetting polyimide resin is 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, Sen'i Gakkaishi Journal, "Sen'i to Kogyo," Vol. 50, No. 3 (1994), pp. 106-118.

[0102] Epoxy resins as thermosetting components have the property of forming a three-dimensional network structure and a strong coating when heated. 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.

[0103] 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.

[0104] When a thermosetting component is used as the curing component (B), it is preferable to use a curing agent (C) as an auxiliary. For example, a heat-activated latent epoxy resin curing agent is preferred as a curing agent 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. Methods for activating heat-activated latent epoxy resin curing agents include generating active species (anions and cations) through a chemical reaction upon 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] The content of the curing agent (C) may be 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, 0.3 to 3 parts by mass, or 0.4 to 2 parts by mass, relative to 100 parts by mass of the curable component (B). By setting the content of the curing agent (C) within the above range, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0110] 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.

[0111] The content of the curing accelerator (D) may be 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, 0.3 to 3 parts by mass, or 0.4 to 2 parts by mass, relative to 100 parts by mass of the curable component (B). By setting the content of the curing accelerator (D) within the above range, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0112] When the total weight of the composition for the protective film-forming film (i.e., the mass of the protective film-forming film) is taken as 100 parts by mass, the total content of the thermosetting component and the curing agent may be 1 to 50 parts by mass, 2 to 40 parts by mass, 3 to 30 parts by mass, 5 to 25 parts by mass, or 10 to 20 parts by mass. When the thermosetting component and the curing agent are blended in such a ratio, the protective film is likely to have the ability to protect the workpiece.

[0113] (2.1.3. 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.

[0114] 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.

[0115] 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.

[0116] (2.1.4 Filler) By containing 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 adjust the thermal expansion coefficient, and by making this thermal expansion coefficient closer to the thermal expansion coefficient of the workpiece, the adhesive reliability with the workpiece can be further improved. Also, by containing the filler (E) in the protective film-forming film, a hard protective film can be obtained, making it easier to obtain the performance of protecting the workpiece, and furthermore, the moisture absorption rate of the protective film can be reduced.

[0117] 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.

[0118] 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.

[0119] The average particle size of the filler is preferably 0.02 to 10 μm, 0.05 to 5 μm, or 0.10 to 3 μm.

[0120] By setting the average particle size of the filler within the above range, the composition for a protective film-forming film can be easily handled, and as a result, the quality of the composition for a protective film-forming film and the protective film-forming film can be easily stabilized.

[0121] 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.

[0122] When the total weight of the composition for the protective film-forming film (i.e., the mass of the protective film-forming film) is 100 parts by mass, the content of the filler may be 20 to 80 parts by mass, 30 to 75 parts by mass, 40 to 70 parts by mass, or 50 to 65 parts by mass.

[0123] By setting the lower limit of the filler content to the above value, the effect of containing the filler described above can be more easily obtained. 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 can be improved, and the adhesive strength of the protective film to the workpiece can be appropriately improved.

[0124] 2.1.5. 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 further 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.

[0125] 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 imidazolesilane. These may be used alone or in combination of two or more.

[0126] Preferred examples of the silane coupling agent include oligomeric silane coupling agents having multiple alkoxysilyl groups in one molecule. The oligomeric silane coupling agent is preferred in that it is less likely to volatilize and has multiple alkoxysilyl groups in one molecule, making it effective in improving the durability of the protective film.

[0127] Examples of the oligomeric silane coupling agents include epoxy group-containing oligomeric silane coupling agents "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 "X-41-1818," "X-41-1810," and "X-41-1805" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0128] When the total weight of the composition for the protective film-forming film (i.e., the mass of the protective film-forming film) is 100 parts by mass, the content of the coupling agent may be 0.03 to 3 parts by mass, 0.05 to 2 parts by mass, or 0.1 to 1 part by mass.

[0129] (2.1.6. Colorants) The protective film-forming film preferably contains a colorant (G), which conceals the back surface of the workpiece singulated, such as a chip, thereby blocking various electromagnetic waves generated within electronic devices and reducing malfunction of the workpiece singulated.

[0130] As the colorant (G), known colorants such as organic pigments, organic dyes, and inorganic pigments can be used. In this embodiment, organic pigments are preferred. By using organic pigments, it tends to be easier to keep the line width change within the above-mentioned range. On the other hand, it is preferable not to use inorganic pigments, such as carbon black, as colorants.

[0131] Examples of organic pigments and organic dyes include aminium-based dyes, cyanine-based dyes, merocyanine-based dyes, croconium-based dyes, squarium-based dyes, azulenium-based dyes, polymethine-based dyes, naphthoquinone-based dyes, pyrylium-based dyes, phthalocyanine-based dyes, naphthalocyanine-based dyes, naphtholactam-based dyes, azo-based dyes, condensed azo-based dyes, indigo-based dyes, perinone-based dyes, perylene-based dyes, dioxazine-based dyes, quinacridone-based dyes, isoindolinone-based dyes, quinophthalone-based dyes, pyrrole-based dyes, thioindigo-based dyes, metal complex-based dyes (metal complex dyes), dithiol metal complex-based dyes, indolephenol-based dyes, triallylmethane-based dyes, anthraquinone-based dyes, dioxazine-based dyes, naphthol-based dyes, azomethine-based dyes, benzimidazolone-based dyes, pyranthrone-based dyes, and threne-based dyes. The organic colorant may be composed of one type of material, or may be composed of multiple types of materials.

[0132] The amount of the colorant blended in the protective film-forming film also varies depending on the thickness of the protective film-forming film. For example, when the thickness of the protective film-forming film is 25 μm, the content of the colorant may be 0.1 to 7 parts by mass or 0.2 to 4 parts by mass when the total weight of the composition for the protective film-forming film (i.e., the mass of the protective film-forming film) is 100 parts by mass.

[0133] (2.1.7. Other additives) The composition for a protective film-forming film may contain, as other additives, for example, a photopolymerization initiator, an ultraviolet absorber, a crosslinking agent, a plasticizer, an antistatic agent, an antioxidant, a gettering agent, a tackifier, a release agent, etc., within a range that does not impair the effects of the present invention. When the total weight of the composition for a protective film-forming film (i.e., the mass of the protective film-forming film) is taken as 100 parts by mass, the content of other additives may be less than 4 parts by mass or less than 2 parts by mass.

[0134] (3. Production of protective film-forming film) The protective film-forming film can be produced by a known method. For example, the protective film-forming film can be produced using the above-mentioned composition for a protective film-forming film or a composition obtained by diluting the composition for a protective film-forming film with a solvent (these compositions are referred to as "coating agents"). The coating agent is prepared by mixing the components constituting the composition for a protective film-forming film by a known method.

[0135] The obtained coating agent is applied to the release surface of the first release film using a coating machine such as a roll coater, a knife coater, a roll knife coater, an air knife coater, a die coater, a bar coater, a gravure coater, a curtain coater, etc. If necessary, the solvent in the coating agent is removed by drying to form a protective film-forming film on the first release film.

[0136] When producing a sheet for forming a protective film, it is obtained by further laminating the release surface of a second release film to the exposed surface of the protective film-forming film formed on the first release film.

[0137] Furthermore, when manufacturing a composite sheet for forming a protective film, a laminate including a pressure-sensitive adhesive sheet and the above-mentioned sheet for forming a protective film can be used. The pressure-sensitive adhesive sheet can be manufactured by a known method. For example, a composition constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is prepared, 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. Next, a substrate is attached to the exposed pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive sheet in which the third release film is disposed on the pressure-sensitive adhesive layer.

[0138] Next, the second release film of the sheet for forming a protective film is peeled off, and the third release film of the pressure-sensitive adhesive sheet is peeled off, and the protective film-forming film and the pressure-sensitive adhesive layer are bonded together to obtain a composite sheet for forming a protective film. If necessary, after peeling off the first release film, a jig pressure-sensitive adhesive layer is formed on the peripheral portion of the exposed pressure-sensitive adhesive layer.

[0139] The protective film-forming film may be cut out to the size of the adherend (for example, a wafer) to which it is to be attached or to a size close to the size of the adherend, as needed. [Example]

[0140] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0141] (Preparation of protective film forming sheet) A sheet for forming a protective film including a thermosetting protective film-forming film was prepared as follows using a coating agent including the composition for forming a protective film described below.

[0142] (Preparation of coating agent containing composition for protective film-forming film) The raw materials used in the production of the protective film-forming film composition are shown below. Polymer component (A): a (meth)acrylic acid ester copolymer obtained by copolymerizing 87 parts by mass of methyl acrylate and 13 parts by mass of 2-hydroxyethyl acrylate. Curing component (B) (thermosetting component) (B-1) Bisphenol A epoxy resin (Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184-194g / eq) (B-2) Dicyclopentadiene-type epoxy resin (DIC Corporation, Epicron HP-7200, epoxy equivalent 254-264 g / eq) Curing agent (C): Dicyandiamide (DICY7, manufactured by Mitsubishi Chemical Corporation) Curing accelerator (D): 2-phenyl-4,5-dihydroxymethylimidazole (Curezol 2PHZ, manufactured by Shikoku Chemicals Corporation) Filler (E): Epoxy-modified spherical silica filler (manufactured by Admatechs Co., Ltd., SC2050MA, average particle size 0.5 μm) Coupling agent (F): Epoxy group-containing oligomer-type silane coupling agent (Shin-Etsu Chemical Co., Ltd., X-41-1056, epoxy equivalent 280 g / eq) Colorant (G): Organic black pigment (Dainichiseika Color & Chemicals Mfg. Co., Ltd., 6377 Black)

[0143] The above components were mixed and diluted with methyl ethyl ketone to a solid content of 65% by mass to prepare a coating agent containing a composition for a protective film-forming film. The blending ratio (solid content equivalent) was 25 parts by mass of polymer component (A), 10 parts by mass of curable component (B-1), 5 parts by mass of curable component (B-2), 0.1 parts by mass of curing agent (C), 0.1 parts by mass of curing accelerator (D), 57.5 parts by mass of filler (E), 0.3 parts by mass of coupling agent (F), and 2 parts by mass of colorant (G).

[0144] 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.

[0145] The coating agent containing each of the prepared compositions for the protective film-forming film 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, the release-treated surface of the prepared second release film was attached to the surface of the protective film-forming film to obtain a protective film-forming sheet (Examples 1 to 8) in which release films were arranged on both sides of the protective film-forming film. The attachment conditions were a temperature of 60°C, a pressure of 0.4 MPa, and a speed of 1 m / min.

[0146] (Preparation of composite sheet for forming protective film) The second release film was peeled off from the protective film-forming sheet obtained above, and a support sheet having a polypropylene substrate (thickness 80 μm) with a surface roughness Ra of 0.2 μm and an acrylic transparent adhesive layer (thickness 5 μm) was attached to the exposed protective film-forming film using a roller maintained at room temperature, thereby obtaining a composite sheet for protective film formation with a first release film (Examples 9 to 11 and Comparative Example 1). The haze of the support sheet (based on JIS K 7136:2000, device: NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.), light source: white LED (5 V, 3 W)) was 47%.

[0147] Subsequently, as shown below, the protective film-forming film possessed by the obtained sheets for forming a protective film and composite sheets for forming a protective film of the examples and comparative examples was converted into a protective film, and then laser marking was performed on the protective film.

[0148] (Laser marking on protective film forming sheet) The second release film was peeled off from the obtained protective film-forming sheet. The exposed protective film-forming film was attached to a #2000 ground surface (surface ground with a #2000 wheel) of a silicon wafer (silicon thickness after grinding: 350 μm, diameter: 200 mm) on which bumps were formed on the surface, using a roller maintained at 70 ° C. After attachment, the first release film was peeled off, and the protective film-forming film was cured by heating in a heating oven at 140 ° C. for 2 hours. After curing, the film was allowed to cool to 23 ° C., and a protective film formed on the #2000 ground surface of the silicon wafer was obtained.

[0149] Laser marking was performed on the obtained protective film using a UV laser marker (Keyence Corporation, MD-U1000C) by irradiating it with a laser with a wavelength of 355 nm under the conditions (scanning speed, Q-switch frequency, laser output) shown in Table 1. For the laser marking, 20 letters from the alphabet "A" to "T" were marked in four lines of five letters each. The size of each letter was a maximum height of 300 μm and a maximum width of 200 μm. The order of the 20 letters was random, not alphabetical order.

[0150] (Laser marking on composite sheet for forming protective film) The first release film was peeled off from the composite sheet for forming a protective film with the first release film obtained above. Using the same method as for the sheet for forming a protective film, a composite sheet for forming a protective film attached to the #2000 ground surface of a silicon wafer with bumps formed on its surface was obtained. After attachment, the protective film-forming film was cured by heating in a heating oven at 140°C for 2 hours. After curing, it was allowed to cool to 23°C, and a protective film formed on the #2000 ground surface of the silicon wafer was obtained. Laser marking was performed on the obtained protective film through the support sheet under the conditions shown in Table 1 using the same method as for the sheet for forming a protective film, except that laser marking was performed.

[0151] (Silicon wafer dicing) After laser marking, the protective film-coated silicon wafers were singulated. For the protective film-coated silicon wafers formed with the protective film-forming sheet attached, dicing tape (Lintec Corporation, Adwill D-676H) was applied to the protective film, and the wafers were diced using a dicing device. The wafers were then picked up from the dicing tape to obtain a set of 5 mm x 5 mm square protective film-coated chips (protective film-coated workpieces). For the protective film-coated silicon wafers formed with the protective film-forming composite sheet attached, the protective film-coated chips were obtained in the same manner as for the silicon wafers with the protective film-coated sheet attached, except that the dicing tape was not applied and the wafers were picked up from the support sheet. During dicing, a general-purpose stainless steel ring frame (for 8-inch wafers) was used to secure the laminate of the protective film-coated silicon wafer and dicing tape, or the laminate of the protective film-coated silicon wafer and support sheet.

[0152] In the obtained chip with the protective film, the distances D1 to D4 from the four vertices of the protective film to the marked characters were D1 400 μm, D2 400 μm, D3 450 μm, and D4 500 μm, respectively.

[0153] The obtained chip with protective film is placed on a substrate with the side on which the bumps are formed facing the circuit side of the substrate, and the chip with protective film is heated using a reflow furnace, for example, under the following conditions to melt the bumps, thereby manufacturing a device (a semiconductor device with a chip with protective film mounted thereon).

[0154] (reflow process) The resulting chips with protective film were heat-treated using a reflow furnace (STR-2010M, manufactured by Senju Metals Co., Ltd.) under the following conditions. The heating zones in the furnace were divided into five zones based on the set temperature profile, the conveying speed in the furnace was 13 cm / min, and the total heating time was 14 minutes. The length and set temperature of each zone were as follows: Zone Length Zone 1 355mm Zone 2 355mm Zone 3 355mm Zone 4 400mm Zone 5 355mm Set temperature Zone 1 Upper furnace: 290℃ Lower furnace: 290℃ Zone 2 Upper furnace: 250℃ Lower furnace: 250℃ Zone 3 Upper furnace: 220℃ Lower furnace: 220℃ Zone 4 Upper furnace: 260℃ Lower furnace: 260℃ Zone 5 Upper furnace: 380℃ Lower furnace: 380℃

[0155] Before transferring the protective film-coated chip to the reflow furnace, a thermocouple was fixed in contact with the protective film, and the temperature of the protective film was measured while transferring the protective film-coated chip into the reflow furnace. As a result, the maximum temperature reached was 277°C, and the time during which the protective film temperature reached 265°C or higher was 47 seconds.

[0156] The protective film that had been laser marked was evaluated as follows.

[0157] (Measurement of marking line width A before reflow process) For the protective film-attached chip before the reflow process, the surface of the protective film on which laser marking had been performed was observed under an optical microscope (Keyence VHX-7000) at a magnification of 1000x using a ring light as the light source, and the line width of the marking was measured. The narrowest line width measured was designated as line width A. The results are shown in Table 1.

[0158] (Measurement of marking line width B after reflow process) In the chip with the protective film after the reflow process, the line width of the portion corresponding to the measurement position of line width A was measured using the same method as for the line width of the marking before reflow, and was defined as line width B. The results are shown in Table 1.

[0159] (Line width change amount and change rate) The line width change amount (BA) μm and the line width change rate (100×(BA) / A) % were calculated from the line width A and line width B obtained above. The results are shown in Table 1.

[0160] (Visibility of marking after reflow process) The visibility of the markings on the protective film-attached chips after the reflow process was evaluated visually using the method described below. Under fluorescent lighting, 10 evaluators were asked to determine whether they could see all 20 of the marked characters within 20 seconds of starting observation, according to the following criteria. The results are shown in Table 1. AA (Pass): All 10 evaluators were able to see all 20 characters A (Pass)...One or two out of ten evaluators were unable to see all 20 characters. B (Pass): 3-4 out of 10 evaluators could not see all 20 characters. C (Fail): 5 or more of the 10 evaluators could not see all 20 characters.

[0161] (Visual evaluation of changes in marking line width before and after the reflow process) Ten evaluators visually inspected the marking line width of the protective film-equipped chips before the reflow process under fluorescent lighting for 30 seconds and memorized it. Next, ten evaluators visually inspected the marking line width of the protective film-equipped chips after the reflow process under fluorescent lighting for 30 seconds and evaluated whether the marking line width was wider than the line width before the reflow process according to the following criteria. The results are shown in Table 1. AA (pass): All 10 evaluators judged the line width to be wider. A (Pass) - 9 out of 10 evaluators judged the line width to be wider B (Pass) - 7-8 out of 10 evaluators judged the line width to be wider. C (Fail): Six or fewer of the ten evaluators judged the line width to have widened.

[0162] [Table 1]

[0163] From Table 1, it was confirmed that when the change in the line width of the marking before and after the reflow process was within the above-mentioned range, the increase in the line width could be visually confirmed. As a result, in addition to improving the visibility of the marking, it was possible to easily evaluate whether the temperature required to melt the convex electrode was reached in the reflow process based on the change in the line width of the marking before and after the reflow process. [Explanation of symbols]

[0164] 1...Protective film forming film 2…Protective film 101...Chip with protective film (workpiece with protective film) 101a...Chip (workpiece) 101b...Convex electrode 300...Device having a tip with a protective film (a workpiece with a protective film)

Claims

1. a step of attaching a protective film-forming film to a back surface of a workpiece having a front surface on which a convex electrode is formed and a back surface opposite to the front surface; A step of forming the attached protective film-forming film into a protective film to obtain a workpiece with a protective film; a marking step of performing laser marking on the protective film to form a marking on the surface of the protective film; A step of dividing the protective film-coated workpiece into individual pieces to obtain a plurality of protective film-coated workpieces; a placement step of placing the protective film-attached workpiece on a substrate; a reflow process for heating the protective film-attached workpiece in a reflow furnace to melt the convex electrode after the marking process and the arranging process, A method for manufacturing a device having a workpiece with a protective film, in which, when the line width of the marking before the reflow process is A and the line width of the marking after the reflow process is B, A is 20 μm or more and (B-A), which indicates the amount of change in line width, is 5 μm or more.

2. 2. The method for manufacturing a device having a workpiece with a protective film according to claim 1, wherein the time during which the temperature of the workpiece with a protective film is 265[deg.] C. or higher is 30 seconds or more in total during the reflow process.

3. 3. The method for manufacturing a device having a workpiece with a protective film according to claim 1, wherein (100×(B−A) / A), which indicates the rate of change in line width, is 10% or more.

4. 3. The method for manufacturing a device having a workpiece with a protective film according to claim 1, wherein B is 40 μm or more.

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