Bonding sheet, method for using bonding sheet, and method for manufacturing semiconductor device

Abstract

This bonding sheet includes: a base material; and an adhesive layer provided on one surface of the base material. In the bonding sheet, the transmittance of infrared light having a wavelength of 1600 nm is 80% or more. The peeling force between a silicon chip and an energy ray-irradiated product of the adhesive layer, as measured using a test piece that is a laminate of the silicon chip, the energy ray-irradiated product of the adhesive layer, and the base material, is 5 N or less.

Description

Bonding sheet, method of using the bonding sheet, and method of manufacturing a semiconductor device.

[0001] The present invention relates to a bonding sheet, a method of using a bonding sheet, and a method of manufacturing a semiconductor device. This application claims priority based on Japanese Patent Application No. 2024-179845, filed in Japan on October 15, 2024, the contents of which are incorporated herein by reference.

[0002] Some semiconductor chips have circuits formed on one side (the circuit side), and some also have protruding electrodes such as bumps on that side (circuit side). When mounting such a chip onto a circuit board, a common method is to orient the circuit side of the chip towards the circuit side of the circuit board and connect the protruding electrodes on the circuit side of the chip to connection pads on the circuit board.

[0003] However, with this connection method, there are concerns that the occurrence of problems related to protruding electrodes, such as short circuits, will increase as circuits become smaller in recent years. Therefore, new methods are being considered for mounting chips onto circuit boards without using protruding electrodes.

[0004] One such new method involves creating chips by dividing a wafer on a dicing sheet, transferring the chips from the dicing sheet to a carrier sheet, and then plasma-treating both the exposed surface of the chip that will be bonded to the circuit board and the exposed surface of the circuit board that will be bonded to the chip on the carrier sheet. This process modifies these exposed surfaces to make them hydrophilic, and then bonding them by directly contacting these modified exposed surfaces (see Patent Documents 1-2). In this case, since the chip is directly bonded to the circuit board, there is no need to provide protruding electrodes on the chip, thus preventing the occurrence of problems related to protruding electrodes.

[0005] Japanese Patent No. 6367084 Japanese Patent No. 6900006

[0006] By the way, in the methods for bonding a chip to a circuit board disclosed in Patent Documents 1 and 2, in order to accurately bond the chip to the desired location on the circuit board, it is necessary to use a carrier sheet on which the chip is attached and to align the chip with respect to the circuit board while observing the circuit board through the carrier sheet. Furthermore, after bonding the chip to the circuit board, it is necessary to remove the carrier sheet from the chip, and in that case, the carrier sheet must be easily peeled off from the chip.

[0007] In contrast, Patent Documents 1 and 2 primarily disclose details of methods for bonding chips to circuit boards. While Patent Documents 1 and 2 disclose that the carrier sheet is made of a light-transmitting transparent resin to cure the UV-curable adhesive layer on its surface, they do not disclose any other characteristics. These adhesive layers are all designed to facilitate the removal of the chip from the carrier sheet through UV curing.

[0008] Up to this point, we have described the case of joining a chip to a circuit board, but similar joining methods are not limited to chips and can be applied to all workpieces obtained by processing a workpiece. Furthermore, the object to be joined is not limited to a circuit board, but may also be a wafer, etc. However, the same problems as described above exist in these cases as well.

[0009] The present invention provides a bonding sheet for joining a workpiece to an object by holding the workpiece and bringing the workpiece into direct contact with the object, wherein it is possible to align the workpiece with the object while observing the object through the bonding sheet, and the bonding sheet can be easily peeled off the workpiece after it has been joined to the object.

[0010] To solve the above problems, the present invention adopts the following configuration: [1] A bonding sheet comprising a base material and an adhesive layer provided on one surface of the base material, wherein the bonding sheet is for bonding a workpiece to an object by holding the workpiece on the side of the adhesive layer opposite to the base material side, and bringing the side of the workpiece opposite to the bonding sheet side into direct contact with the object, wherein the transmittance of the infrared light measured by irradiating the bonding sheet with infrared light of a wavelength of 1600 nm from outside the side of the base material is 80% or more, and the adhesive layer in the bonding sheet is applied to a silicon chip with a thickness of 150 μm and a size of 6 mm x 6 mm at room temperature at an application speed of 0.6 mm / min, and the illuminance of the adhesive layer is 230 mW / cm². ２ , light intensity 190mJ / cm ２ A bonded sheet is prepared by irradiating the silicon chip with energy rays under the following conditions, thereby creating a laminate of the silicon chip, the energy-irradiated object of the adhesive layer, and the substrate; and in the test piece, the silicon chip is pushed up with a pin from the outside of the substrate side under the conditions of a push-up height of 200 μm, a push-up speed of 10 mm / s, and a push-up time of 100 ms, and the silicon chip is picked up by pulling it away from the energy-irradiated object of the adhesive layer in the direction of the push-up by the pin, and the peel force between the energy-irradiated object of the adhesive layer and the silicon chip is measured to be 5 N or less.

[0011] [2] The bonding sheet according to [1], wherein the peeling force is 0.01 N or more. [3] The bonding sheet according to [1] or [2], wherein the object is a wafer. [4] The bonding sheet according to any one of [1] to [3], wherein the bonding surface of the workpiece to the object and the bonding surface of the object to the workpiece are modified. [5] The bonding sheet according to [4], wherein both bonding surfaces are modified by plasma treatment or ozone treatment.

[0012] [6] A method of using the bonding sheet described in any one of [1] to [5], wherein in the method of use, a workpiece is placed on the side of the adhesive layer in the bonding sheet opposite to the side of the substrate, the side of the workpiece opposite to the side of the bonding sheet is placed opposite to one side of the object to be bonded, the workpiece is aligned with the object while observing the object through the bonding sheet, the aligned workpiece is pressed against the object through the bonding sheet to bond the workpiece to the object by bringing it into direct contact with the object, and if the adhesive layer is energy ray curable, energy rays are irradiated onto the adhesive layer at any timing between placing the workpiece on the bonding sheet and bonding the workpiece to the object to make the adhesive layer energy ray cured. A method for using a bonding sheet, wherein if the adhesive layer is energy-ray curable, the energy-ray cured portion of the adhesive layer is peeled off from the workpiece bonded to the object by releasing the pressure on the workpiece, and if the adhesive layer is not energy-ray curable, the bonding sheet is peeled off from the workpiece bonded to the object by peeling off the adhesive layer.

[0013] [7] A method for using a bonding sheet as described in [6], wherein a semiconductor chip is used as the workpiece and a circuit board is used as the target object, and after peeling the bonding sheet from the semiconductor chip bonded to the circuit board, a semiconductor device is manufactured using the circuit board to which the semiconductor chip is bonded.

[0014] According to the present invention, a bonding sheet is provided for bonding a workpiece to an object by holding the workpiece and bringing the workpiece into direct contact with the object, wherein it is possible to align the workpiece with respect to the object while observing the object through the bonding sheet, and the bonding sheet can be easily peeled off the workpiece after bonding to the object.

[0015] This is a schematic cross-sectional view showing an example of a bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention. This is a schematic cross-sectional view illustrating an example of a method of using the bonding sheet according to one embodiment of the present invention.

[0016] ◇Bonding Sheet A bonding sheet according to one embodiment of the present invention comprises a base material and an adhesive layer provided on one surface of the base material, wherein the bonding sheet is for bonding a workpiece to an object by holding the workpiece on the side of the adhesive layer opposite to the base material side, and bringing the side of the workpiece opposite to the bonding sheet side into direct contact with the object, wherein the transmittance of the infrared light measured by irradiating the bonding sheet with infrared light of wavelength 1600 nm (sometimes referred to as "infrared light (1600 nm)" in this specification) from outside the side of the base material is 80% or more, and the adhesive layer in the bonding sheet is applied to a silicon chip with a thickness of 150 μm and a size of 6 mm x 6 mm at room temperature at an application speed of 0.6 mm / min, and the illuminance of the adhesive layer is 230 mW / cm². ２ , light intensity 190mJ / cm ２A test piece is prepared by irradiating the silicon chip with energy rays under the specified conditions, the test piece being a laminate of the silicon chip, the energy-irradiated adhesive layer, and the substrate. In the test piece, the silicon chip is pushed up with a pin from the outside of the substrate side under the conditions of a push-up height of 200 μm, a push-up speed of 10 mm / s, and a push-up time of 100 ms. The peeling force between the energy-irradiated adhesive layer and the silicon chip, measured when the silicon chip is picked up by pulling it away from the energy-irradiated adhesive layer in the direction of the push-up by the pin, is 5 N or less.

[0017] Because the infrared (1600 nm) transmittance is 80% or more, when joining a workpiece to an object by holding the workpiece and bringing the workpiece into direct contact with the object using the bonding sheet of this embodiment, the workpiece can be positioned relative to the object while observing the object through the bonding sheet. Furthermore, because the peeling force measured using the test piece is 5 N or less, the bonding sheet of this embodiment can be easily peeled off the workpiece after it has been joined to the object. The bonding sheet of this embodiment functions as a carrier sheet that enables both the positioning of the workpiece before joining and the peeling of the bonding sheet from the workpiece after joining, when transferring and joining a workpiece to an object.

[0018] In this specification, regardless of whether the adhesive layer is energy-curable or not, a bonded sheet after irradiating the adhesive layer with energy rays may also be referred to as a "bonded sheet" as long as the laminated structure of the substrate and the energy-irradiated adhesive layer is maintained.

[0019] In this embodiment, examples of workpieces include wafers and semiconductor device panels.

[0020] Examples of the aforementioned wafers include semiconductor wafers composed of elemental semiconductors such as silicon, germanium, and selenium, and compound semiconductors such as GaAs, GaP, InP, CdTe, ZnSe, and SiC; and insulating wafers composed of insulators such as sapphire and glass. A circuit is formed on one side of a workpiece, such as these wafers, and this side is the circuit side. On the other hand, the side of the workpiece opposite the circuit side is the back side. The wafer is divided into chips by means of dicing or other means. The side of the chip on which the circuit is formed is also the circuit side, and the side of the chip opposite the circuit side is also the back side.

[0021] The aforementioned semiconductor device panel is handled during the manufacturing process of a semiconductor device. A specific example of such a panel is a semiconductor device in which one or more electronic components are sealed with a sealing resin, and multiple such semiconductor devices are arranged planarly within a circular, rectangular, or other shaped area.

[0022] In this embodiment, the workpiece is obtained by processing a workpiece. For example, if the workpiece is a wafer, the workpiece is a chip, and if the workpiece is a semiconductor wafer, the workpiece is a semiconductor chip.

[0023] In this embodiment, the object to be joined in the workpiece is not particularly limited and may be the same as the object to be joined in conventional workpieces having protruding electrodes. For example, the object to be joined may be a circuit board, a wafer, etc., with wafers being preferred. The wafer as the object to be joined is the same as that described above.

[0024] <<Infrared (1600nm) transmittance of the bonding sheet>> The infrared transmittance of the bonding sheet, measured by irradiating it with infrared light of a wavelength of 1600nm from the outside of the substrate side toward the adhesive layer, was 80% or more, indicating that the infrared (1600nm) transmittance of the bonding sheet is high.

[0025] In this specification, unless otherwise specified, the infrared (1600 nm) transmittance of the bonded sheet means a measurement obtained by irradiating the bonded sheet with infrared (1600 nm) light from the outside of the substrate side of the bonded sheet, and measuring the infrared (1600 nm) light transmitted through the bonded sheet by direct light reception without using an integrating sphere on the outside of the adhesive layer side of the bonded sheet.

[0026] In terms of achieving the above effects more effectively, the infrared (1600nm) transmittance of the bonded sheet is preferably 83% or higher, more preferably 86% or higher, and even more preferably 89% or higher. For example, it may be 90.5% or higher and 91.5% or higher. On the other hand, the infrared (1600nm) transmittance of the bonded sheet is 100% or less, and in terms of making the bonded sheet easier to realize, it is preferably 99% or less. In one embodiment, the infrared (1600nm) transmittance of the bonded sheet may be, for example, 80-100%, 83-100%, 86-100%, 89-100%, 90.5-100%, and 91.5-100%, or it may be 80-99%, 83-99%, 86-99%, 89-99%, 90.5-99%, and 91.5-99%. However, these are just examples of the infrared (1600 nm) transmittance of bonded sheets.

[0027] The infrared (1600 nm) transmittance of the bonded sheet can be adjusted, for example, by adjusting the type and content of components contained in the substrate and adhesive layer. For example, the infrared (1600 nm) transmittance of the bonded sheet can be increased by ensuring that the substrate or adhesive layer does not contain components with high infrared shielding properties, such as carbon black, fillers, and colorants, or by keeping their content low even if they are present. The infrared (1600 nm) transmittance of the bonded sheet can also be increased by ensuring that the bonded sheet does not have a layer with high infrared reflectivity, such as an aluminum film. The infrared (1600 nm) transmittance of the bonded sheet can also be adjusted by adjusting the surface roughness of the surface of the substrate opposite to the adhesive layer (i.e., the exposed surface). For example, the infrared (1600 nm) transmittance can be increased by reducing the surface roughness, and the infrared (1600 nm) transmittance can be decreased by increasing the surface roughness. Examples of the aforementioned surface roughness include the arithmetic mean roughness (Ra) and maximum height roughness (Rz), measured in accordance with JIS B 0601:2013. However, these are merely examples.

[0028] <<Peel force between the energy ray irradiated object in the adhesive layer of the bonding sheet and the silicon chip>> At room temperature, when the silicon chip is pushed up through the bonding sheet with a pin from the outside of the substrate side of the test piece toward the silicon chip under the above conditions, and the silicon chip is picked up by pulling it away from the energy ray irradiated object in the adhesive layer toward the direction of the pin push, the peel force measured is 5 N or less. In other words, the peel force is small within an appropriate range.

[0029] During the pickup process, the silicon chip can be pushed up by a plurality of pins, such as five.

[0030] As described below, the adhesive layer in the bonding sheet may be energy-ray curable, non-energy-ray curable (may be thermosetting or not), or non-curable.

[0031] In this specification, "energy ray" means an electromagnetic wave or charged particle beam that has an energy quantum. Examples of energy rays include ultraviolet rays, radiation, and electron beams. "Energy ray curability" means the property of hardening when irradiated with energy rays, and "non-energy ray curability" means the property of not hardening even when irradiated with energy rays. "Thermosetting property" means the property of hardening when heated. "Non-curing property" means the property of not hardening by either heating or irradiation with energy rays.

[0032] In this specification, "energy-irradiated material of an energy-ray curable adhesive layer" means the energy-ray cured material of the adhesive layer unless otherwise specified. On the other hand, an energy-irradiated material of a non-energy-ray curable adhesive layer is substantially identical to the adhesive layer, or is exactly the same as the adhesive layer, or is so similar to the adhesive layer that no clear differences in physical properties can be identified. That is, the peeling force is the peeling force between the energy-ray cured material of the adhesive layer and the silicon chip when the adhesive layer is energy-ray curable, and substantially the peeling force between the adhesive layer and the silicon chip when the adhesive layer is not energy-ray curable.

[0033] When preparing the aforementioned test specimen, the surface of the silicon chip to which the bonding sheet (adhesive layer) is attached is preferably a surface ground by dry polishing, as will be described later in the examples.

[0034] When the adhesive layer is energy-ray curable, the illuminance of the energy rays used to cure the adhesive layer during actual use of the bonded sheet is 60 to 320 mW / cm². ２ Preferably, the amount of energy rays is 100 to 1000 mJ / cm². ２ This is preferable. Under these conditions, the degree of curing of the energy ray-cured product of the adhesive layer becomes sufficiently high.

[0035] In terms of achieving the above-mentioned effects more effectively, the peeling force of the bonding sheet may be, for example, 4.5 N or less, 3.5 N or less, or 3 N or less. On the other hand, in terms of effectively suppressing unintended peeling between the energy ray irradiated object and the silicon chip in the adhesive layer of the bonding sheet, the peeling force of the bonding sheet is preferably 0.01 N or more, and may be, for example, 0.1 N or more, 1 N or more, or 1.5 N or more. In one embodiment, the peel force of the bonding sheet may be, for example, any of 0.01 to 5 N, 0.01 to 4.5 N, 0.01 to 3.5 N, and 0.01 to 3 N; any of 0.1 to 5 N, 0.1 to 4.5 N, 0.1 to 3.5 N, and 0.1 to 3 N; any of 1 to 5 N, 1 to 4.5 N, 1 to 3.5 N, and 1 to 3 N; or any of 1.5 to 5 N, 1.5 to 4.5 N, 1.5 to 3.5 N, and 1.5 to 3 N. However, these are just examples of the peel force of the bonding sheet.

[0036] The peeling force of the bonding sheet can be adjusted, for example, by adjusting the type and content of the components contained in the adhesive layer.

[0037] <<Example of a Joining Sheet>> Figure 1 is a schematic cross-sectional view showing an example of a joining sheet according to this embodiment. Note that the figures used in the following description are not limited to Figure 1, and for convenience in order to make the features of the present invention easier to understand, key parts may be enlarged, and the dimensional ratios of each component may not be the same as in reality.

[0038] The bonding sheet 101 shown in FIG. 1 is configured to include a base material 11 and an adhesive layer 12 provided on one surface 11a of the base material 11. The bonding sheet 101 further includes a release film 15 provided on a surface (which may be referred to as the "first surface" in this specification) 12a on the side of the base material 11 opposite to the adhesive layer 12. In the bonding sheet 101, the release film 15 has an arbitrary configuration. The adhesive layer 12 may be either energy ray curable or non-energy ray curable. The bonding sheet 101 is used with a workpiece attached to the first surface 12a of the adhesive layer 12 in a state where the release film 15 is removed. The other surface of the base material 11 (in other words, the surface opposite to the side of the adhesive layer 12. This may be referred to as the "second surface" in this specification) 11b is an exposed surface.

[0039] The infrared (1600 nm) transmittance measured by irradiating the bonding sheet 101 with infrared rays (1600 nm) from the outside on the side of the base material 11 is 80% or more. By the above method, the adhesive layer 12 in the bonding sheet 101 (more specifically, the first surface 12a of the adhesive layer 12) is attached to a silicon chip, and the test piece is produced by irradiating the adhesive layer 12 with energy rays. In the test piece, when the silicon chip is pushed up by a pin from the outside on the side of the base material 11 and the silicon chip is picked up by separating it from the energy ray irradiated material of the adhesive layer 12, the peeling force between the energy ray irradiated material of the adhesive layer 12 and the silicon chip is 5 N or less.

[0040] The bonding sheet of this embodiment is not limited to the one shown in FIG. 1. For example, within the scope not departing from the gist of the present invention, in this bonding sheet, some configurations may be changed, deleted, or added. For example, the bonding sheet of this embodiment may or may not include another layer that does not correspond to any of the base material, the adhesive layer, and the release film at an arbitrary location. The other layer can be arbitrarily selected according to the purpose and is not particularly limited.

[0041] <<Method of Using Bonding Sheet>>The bonding sheet of this embodiment can be used to bond a workpiece to an object by directly contacting the workpiece with the object while holding the workpiece on the bonding sheet. For example, when the workpiece is a wafer and the workpiece is a chip, the bonding target surfaces of the chip and the object are pre-modified, and by directly contacting these modified bonding target surfaces, the chip can be bonded to the object without providing a protruding electrode on the chip. Therefore, even if the circuit is fine, problems related to the protruding electrode, such as the occurrence of a short circuit due to the protruding electrode, can be avoided. Further, when bonding the workpiece to the object, the workpiece can be aligned with the object through the bonding sheet. Further, the bonding sheet can be easily peeled off from the workpiece after bonding to the object.

[0042] Figures 2A to 2E and Figures 3A to 3B are cross-sectional views for schematically explaining an example of the method of using the bonding sheet of this embodiment. Here, the case of using the bonding sheet 101 shown in FIG. 1 will be taken as an example to explain the method of using the bonding sheet. In FIGS. 2A to 3B, the display (distinction) of each layer in the bonding sheet 101 is omitted.

[0043] In the above-described method of use, as shown in FIG. 2A, a group of workpieces 190 with a bonding sheet is produced, which includes a bonding sheet 101 and a plurality of workpieces 9 provided on the first surface 12a of the adhesive layer 12 in the bonding sheet 101. Here, the number of workpieces 9 provided on the bonding sheet 101 is a plurality, and the number explicitly shown is 4. However, in the above-described method of use, the number of workpieces 9 on the bonding sheet 101 may be 1 or more, and when it is 2 or more, the number is not particularly limited. When the number of workpieces on the bonding sheet is 1, in the above-described method of use, a workpiece with a bonding sheet is used instead of the group of workpieces 190 with a bonding sheet.

[0044] In the group of workpieces 190 with a bonding sheet, the plurality of workpieces 9 are arranged so as to be separated from each other.

[0045] A group of workpieces 190 with a bonding sheet can be manufactured by known methods. For example, in the case of a group of workpieces 190 with a bonding sheet in which a plurality of workpieces 9 are arranged in a line spaced apart from each other, the method is as follows: A plurality of workpieces 9 are manufactured by dividing a workpiece on a dicing sheet using a known method, and then the dicing sheet is expanded in the direction of its surface. This produces a group of workpieces with a dicing sheet in which a plurality of workpieces 9 are arranged in a line spaced apart from each other on the dicing sheet, with one of their surfaces (sometimes referred to as the "first surface" in this specification) 9a in contact with the dicing sheet. Of the two surfaces of the workpiece, the surface that will become the first surface 9a of the workpiece 9 is attached to the dicing sheet. Next, the other surfaces (sometimes referred to as "second surfaces" in this specification) 9b of multiple workpieces 9 (preferably all usable ones) in the group of workpieces with dicing sheets are collectively attached to the first surface 12a of the adhesive layer 12 in a single bonding sheet 101. Then, the dicing sheets are peeled off from the workpieces 9 by a known method. As a result, multiple workpieces 9, aligned and spaced apart from each other, are transferred from the dicing sheet to the bonding sheet 101, and a group of workpieces 190 with bonding sheets is obtained.

[0046] In the above method of use, the first surface 9a of the workpiece 9 to be joined is then modified, so that the workpiece 9 becomes a workpiece 90 having a modified first surface 90a, as shown in Figure 2B, and the group of workpieces with joining sheets 190 becomes a group of workpieces with joining sheets that have been modified 191. The workpiece 90 is the same as the workpiece 9 except that it has a modified first surface 90a instead of the first surface 9a.

[0047] The modification of the workpiece 9 (more specifically, the first surface 9a of the workpiece 9) is a process for improving the bonding strength of the workpiece 9 to its target object, and is a surface treatment of the workpiece 9, a typical example of which is a process for generating hydroxyl groups (-OH) on the workpiece 9 (the first surface 9a of the workpiece 9). The modification of the workpiece 9 can be carried out by known methods such as plasma treatment, fast atomic bombardment (FAB) treatment, chemical treatment, ultraviolet ozone treatment, etc.

[0048] Plasma treatment can be performed, for example, by setting the nitrogen gas flow rate to 50-150 mL, the output to 150-259 W, and the irradiation time to 30-90 seconds. Ultraviolet ozone treatment can be performed, for example, by setting the treatment time to 30-90 seconds.

[0049] In the above-described method of use, the object to be joined to the workpiece 9 is further modified (sometimes referred to as the "first surface" in this specification) to create an object 80 having a modified first surface 80a, as shown in Figure 2C. The modification of the object (more specifically, the first surface of the object) can be carried out in the same manner as in the case of modifying the workpiece 9 described above. In this way, the joining surface of the workpiece 9 to the object 80 (modified first surface 90a) and the joining surface of the object 80 to the workpiece 9 (modified first surface 80a) are modified, making it possible to join the workpiece 9 and the object 80 at these joining surfaces.

[0050] In the above-described method of use, it is preferable that the bonding surface (modified first surface 90a) of the workpiece 9 with the object 80 and the bonding surface (modified first surface 80a) of the object 80 with the workpiece 9 are both modified by the same treatment, and it is more preferable that both are modified by plasma treatment or ozone treatment. By modifying these bonding surfaces in this way, the bonding force (peeling force) when the workpiece 9 and the object 80 are joined becomes greater, as described later, and the bond structure between the workpiece 9 and the object 80 becomes more stable.

[0051] In the above method of use, as shown in Figure 2D, the modified first surface 90a of the workpiece 90 and the modified first surface 80a of the target object 80 are placed facing each other, thereby arranging the group of workpieces with bonding sheets 191 and the target object 80 opposite each other. Furthermore, at this time, an infrared camera 7 is placed on the side of the group of workpieces with bonding sheets 191 that is opposite to the side of the target object 80 (in other words, on the side of the second surface 11b of the base material 11). The modified first surface 80a of the target object 80 is then observed through the bonding sheet 101 from the infrared camera 7, and the alignment marks provided on it are confirmed, and the workpiece 90 is aligned with the target object 80 using these marks as an indicator. When aligning the workpiece 90 with the target object 80, another camera can be placed in the gap between the group of workpieces with bonding sheets 191 and the target object 80 to confirm the alignment marks.

[0052] In the above-described method of use, the infrared (1600 nm) transmittance of the bonding sheet 101 is 80% or more, so that the workpiece 90 can be aligned with respect to the object 80 via the bonding sheet 101.

[0053] The distance L between the first modified surface 90a of the workpiece 90 and the first modified surface 80a of the object 80 when aligning the workpiece 90 with respect to the object 80. １ This can be set arbitrarily depending on the purpose.

[0054] In the above method of use, as shown in Figure 2E, the workpiece 90, which has been aligned among the group of workpieces 191 with a joining sheet, is then pressed against the object 80 via the joining sheet 101 from the side opposite to the object 80 using the joining means 6, thereby bringing the workpiece 90 into close contact with the object 80 and joining them. At this time, the modified first surface 90a of the workpiece 90 and the modified first surface 80a of the object 80 come into close contact with each other, generating a joining force between them.

[0055] The pressure applied when pressing the workpiece 90 (pressing pressure) is preferably 3 to 7 N per workpiece 90, and the pressing time is preferably 0.1 to 2 seconds.

[0056] The joining means 6 may be a known type, for example, one that is movable at least in the pressing direction of the object to be pressed (in this case, the workpiece 90), and further includes an energy ray transmitting portion 61 inside that enables the irradiation of energy rays onto the object to be pressed. The energy ray transmitting portion 61 is preferably made of a material that can transmit energy rays, such as glass, and its sides are covered with a material that can reflect energy rays, such as metal. Other main parts of the joining means 6 may be made of a material with sufficient strength, such as resin or ceramic, that enables stable pressing of the object.

[0057] Furthermore, while maintaining the above-mentioned close contact state, energy rays are irradiated onto the adhesive layer 12 through the base material 11 in the bonding sheet 101 via the energy ray permeable portion 61 in the bonding means 6, thereby making the adhesive layer 12 an energy ray irradiated object. As a result, the peeling force is 5N or less, which reduces the peeling force between the energy ray irradiated object of the adhesive layer 12 and the workpiece 90, making them easily detachable from each other. The energy ray irradiated object of the adhesive layer 12 may be either an energy ray cured object of the adhesive layer 12 or a substantial adhesive layer. In particular, when the energy ray irradiated object of the adhesive layer 12 is an energy ray cured object, the peeling force is reduced even more significantly, and the energy ray irradiated object of the adhesive layer 12 and the workpiece 90 become even more easily detachable from each other.

[0058] The irradiation conditions for the adhesive layer 12 with energy rays are as described above.

[0059] In the above method of use, the pressing of the workpiece 90 by the joining means 6 is then released. As a result, as shown in Figure 3(a), the workpiece 90, with the pressure released, remains joined to the object 80, and the joining sheet 101 peels off from the workpiece 90. In other words, the pressed workpiece 90 is transferred from the joining sheet 101 to the object 80.

[0060] Subsequently, similar to the case of the transferred workpiece 90, the remaining workpieces 90 in the group of workpieces 191 with bonding sheets are also sequentially aligned with the target object 80, pressed against the target object 80 via the bonding sheet 101, irradiated with energy rays onto the adhesive layer 12 via the base material 11, and released from the pressure on the workpieces 90. As a result, as shown in Figure 3(b), all the desired workpieces 90 can be transferred from the bonding sheet 101 to the target object 80.

[0061] Up to this point, the method of using the bonding sheet has been explained using the example of a case where the adhesive layer 12 in the bonding sheet 101 is treated as an energy ray irradiated object while maintaining close contact between the workpiece 90 and the target object 80. With this method of use, the bonding of the workpiece 90 to the target object 80 and the energy ray irradiation of the adhesive layer 12 can be performed continuously, allowing for efficient transfer of the workpiece 90 to the target object 80.

[0062] On the other hand, in the method of using the bonding sheet of this embodiment, the timing of energy ray irradiation to the adhesive layer is not limited to this. For example, the adhesive layer may be irradiated with energy rays to make the adhesive layer an energy ray irradiated object, and then the aligned workpiece from the group of workpieces with energy ray irradiated bonding sheets may be pressed against the object in the same manner as described above to bond the workpiece to the object. In this case, the energy rays can be irradiated to the adhesive layer via the substrate by irradiating the bonding sheet directly, rather than through the energy ray transmitting portion in the bonding means. Therefore, unlike the case of bonding means 6 described above, a bonding means without an energy ray transmitting portion can be used to bond workpieces, improving the versatility of the method of using the bonding sheet. In this case, the workpiece will not detach from the energy ray irradiated bonding sheet simply by irradiating the adhesive layer with energy rays. The bonding sheet will only peel off the workpiece after the workpiece has been bonded to the object, causing distortion in the bonding sheet, and then releasing the pressure on the workpiece. In this case, when the energy beam is directly irradiated onto the bonding sheet, the adhesive layer in contact with the workpiece other than the object to be bonded may or may not be irradiated with the energy beam.

[0063] In the above-described method of use, if the adhesive layer is non-energy ray curable, it is not necessary to irradiate the adhesive layer with energy rays.

[0064] In the above-described method of use, regardless of the timing of energy ray irradiation to the adhesive layer, and regardless of whether or not energy ray irradiation to the adhesive layer is performed, other steps may or may not be included in addition to the above-described steps, as long as they do not impair the effects of the present invention.

[0065] To summarize the method of using the bonding sheet of this embodiment, for example, a workpiece is placed on the side of the adhesive layer in the bonding sheet opposite to the side of the substrate, the side of the workpiece opposite to the side of the bonding sheet is placed opposite to one side of the object to be bonded, the workpiece is aligned with the object while observing the object through the bonding sheet, the aligned workpiece is pressed against the object through the bonding sheet to bring the workpiece into direct contact with the object and bond it, and if the adhesive layer is energy ray curable, then at some point between placing the workpiece on the bonding sheet and bonding the workpiece to the object, energy rays are irradiated onto the adhesive layer to make it an energy ray cured material. This is a method of using a bonding sheet, wherein if the adhesive layer is energy-ray curable, the energy-ray cured portion of the adhesive layer is peeled off from the workpiece bonded to the object by releasing the pressure on the workpiece, and if the adhesive layer is not energy-ray curable, the bonding sheet is peeled off from the workpiece bonded to the object by peeling off the adhesive layer.

[0066] <<Substrate>> The substrate may be in the form of a sheet or a film, and may be of known type. The substrate is transparent to infrared rays (1600 nm). Examples of constituent materials for the substrate include various resins.

[0067] Examples of the aforementioned resins include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene (mLLDPE), and high-density polyethylene (HDPE); polyolefins other than polyethylene such as polypropylene, polybutene, polybutadiene, polymethylpentene, and norbornene resin; ethylene-based copolymers such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-propylene copolymer, and ethylene-norbornene copolymer (copolymers having constituent units derived from ethylene and other constituent units); vinyl chloride-based polymers such as polyvinyl chloride and vinyl chloride copolymer (polymers having constituent units derived from vinyl chloride); polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyurethane; polyimide; polystyrene; polycarbonate; and fluororesins. The aforementioned resin may be any of the following: a polymer alloy such as a mixture of two or more of the above-mentioned resins; a crosslinked resin obtained by crosslinking one or more of the above-mentioned resins; or a modified resin such as an ionomer using one or more of the above-mentioned resins.

[0068] Among these, preferred resins include polyethylene, ethylene copolymers, and vinyl chloride polymers.

[0069] The substrate may or may not contain various known additives other than the main constituent material such as the resin, such as fillers, colorants, antioxidants, organic lubricants, catalysts, and softeners (plasticizers). However, in order to further increase the infrared (1600 nm) transmittance of the bonded sheet, it is preferable that the substrate does not contain fillers and colorants, or if it contains either of these, the content is at a low level.

[0070] The resin and additive contained in the base material may be one type each, or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0071] In the base material, the ratio of the resin content to the total mass of the base material is preferably 90% by mass or more, and may be, for example, 93% by mass or more, 96% by mass or more, or 99% by mass or more. On the other hand, the ratio is 100% by mass or less.

[0072] The aforementioned one surface of the substrate (the surface facing the adhesive layer) may or may not be subjected to a surface treatment such as embossing, oxidation, or priming in order to improve adhesion with the adhesive layer.

[0073] The second surface of the substrate (the other surface, the exposed surface) may or may not be subjected to the same embossing treatment, oxidation treatment, or primer treatment as the first surface, and may or may not be subjected to lipophilic or hydrophilic treatment. In particular, by embossing the second surface of the substrate, the infrared (1600 nm) transmittance of the bonded sheet can be efficiently adjusted. The degree of embossing of the second surface of the substrate can be expressed by various surface roughness levels.

[0074] For example, the arithmetic mean roughness (Ra) of the second surface of the substrate (sometimes simply referred to as "Ra" in this specification), measured in accordance with JIS B 0601:2013, is preferably 0.01 μm or more when the infrared (1600 nm) transmittance of the bonded sheet is efficiently reduced within an appropriate range. On the other hand, the Ra of the second surface of the substrate is preferably 0.2 μm or less when the infrared (1600 nm) transmittance of the bonded sheet is efficiently increased within an appropriate range, and may be, for example, 0.15 μm or less, 0.1 μm or less, or 0.06 μm or less. In one embodiment, the Ra of the second surface of the substrate may be, for example, 0.01 to 0.2 μm, 0.01 to 0.15 μm, 0.01 to 0.1 μm, or 0.01 to 0.06 μm. However, these are just examples of the Ra of the second surface of the substrate.

[0075] For example, the maximum height roughness (Rz) of the second surface of the substrate (sometimes simply referred to as "Rz" in this specification), measured in accordance with JIS B 0601:2013, is preferably 0.01 μm or more when the infrared (1600 nm) transmittance of the bonded sheet is efficiently reduced within an appropriate range. On the other hand, the Rz of the second surface of the substrate is preferably 1 μm or less when the infrared (1600 nm) transmittance of the bonded sheet is efficiently increased within an appropriate range, and may be, for example, 0.8 μm or less, 0.6 μm or less, or 0.4 μm or less. In one embodiment, the Rz of the second surface of the substrate may be, for example, 0.01 to 1 μm, 0.01 to 0.8 μm, 0.01 to 0.6 μm, or 0.01 to 0.4 μm. However, these are just examples of the Rz of the second surface of the substrate.

[0076] The surface roughness of the second surface or one of the surfaces of the substrate can be adjusted, for example, by pressing a roughness adjustment means having a surface roughness corresponding to the desired surface roughness (e.g., Ra, Rz) against the surface of a film such as a resin film to be used as the substrate, and transferring the surface roughness of the roughness adjustment means to the surface of the film.

[0077] The base material may consist of one layer (single layer) or of two or more layers. If the base material consists of multiple layers, these layers may be identical or different, and the combination of these layers is not particularly limited. In this embodiment, a base material consisting of one layer is usually sufficient.

[0078] In this specification, not only in the case of a substrate, "multiple layers may be identical or different from one another" means "all layers may be identical, all layers may be different, or only some layers may be identical," and further, "multiple layers are different from one another" means "at least one of the constituent materials and thickness of each layer is different from the other."

[0079] The thickness of the substrate is preferably 20 μm or more, and may be, for example, 35 μm or more, or 50 μm or more. A substrate thickness above the lower limit increases the strength and processability of the bonded sheet. On the other hand, the thickness of the substrate is preferably 450 μm or less, and may be, for example, 300 μm or less, 150 μm or less, or 100 μm or less. A substrate thickness below the upper limit increases the infrared (1600 nm) transmittance and processability of the bonded sheet. Here, "substrate thickness" refers to the total thickness of the substrate; for example, the thickness of a substrate consisting of multiple layers refers to the total thickness of all layers constituting the substrate. This also applies to other layers such as the adhesive layer described later.

[0080] In this specification, unless otherwise specified, "thickness" refers to the average of the thicknesses measured at five randomly selected locations on the object, and can be obtained using a constant-pressure thickness measuring instrument in accordance with JIS K7130.

[0081] A preferred substrate is a substrate containing a resin, wherein the resin is one or more selected from the group consisting of polyethylene, ethylene copolymers, and vinyl chloride polymers, the resin content is 90% by mass or more relative to the total mass of the substrate, the arithmetic mean roughness (Ra) of at least one side of the substrate (in the case of a bonding sheet, the exposed surface opposite to the adhesive layer side), measured in accordance with JIS B 0601:2013, is 0.01 to 0.2 μm, and the maximum height roughness (Rz) of at least one side of the substrate (in the case of a bonding sheet, the exposed surface opposite to the adhesive layer side), measured in accordance with JIS B 0601:2013, is 0.01 to 1 μm.

[0082] The substrate can be manufactured by known methods. For example, a substrate containing a resin can be manufactured by molding a resin composition containing the resin. To adjust the surface roughness of the substrate, the surface roughness of the molded body of the resin composition (e.g., the film) can be adjusted by the method described above.

[0083] <<Adhesive Layer>> The adhesive layer is in the form of a sheet or film, contains an adhesive, and is transparent to infrared rays (1600 nm).

[0084] <Adhesive Composition> The adhesive layer can be formed using an adhesive composition containing the adhesive. For example, the adhesive composition can be applied to the surface on which the adhesive layer is to be formed, and dried as necessary to form the adhesive layer in the desired area. The ratio of components that do not vaporize at room temperature in the adhesive composition is usually the same as the ratio of components in the adhesive layer.

[0085] In this specification, "room temperature" means a temperature that is neither cooled nor heated, i.e., a normal temperature, such as 18 to 28°C.

[0086] The adhesive composition can be applied by known methods, such as using various coaters. The drying conditions for the adhesive composition are not particularly limited. If the adhesive composition contains a solvent, as described later, it is preferable to heat-dry it. For example, an adhesive composition containing a solvent is preferably dried at 70 to 130°C for 10 seconds to 5 minutes.

[0087] In the adhesive layer, the ratio of the total content of one or more of the following components in the adhesive layer to the total mass of the adhesive layer shall not exceed 100% by mass. Similarly, in the adhesive composition, the ratio of the total content of one or more of the following components in the adhesive composition to the total mass of the adhesive composition shall not exceed 100% by mass.

[0088] Examples of energy-ray curable adhesive compositions for forming an energy-ray curable adhesive layer include: adhesive composition (I-1) containing a non-energy-ray curable adhesive resin (I-1a) (hereinafter sometimes abbreviated as "adhesive resin (I-1a)") and an energy-ray curable compound; adhesive composition (I-2) containing an energy-ray curable adhesive resin (I-2a) (hereinafter sometimes abbreviated as "adhesive resin (I-2a)") in which an unsaturated group is introduced into the side chain of the adhesive resin (I-1a); and adhesive composition (I-3) containing the adhesive resin (I-2a) and an energy-ray curable compound. By using adhesive composition (I-1), an adhesive layer containing the adhesive resin (I-1a) and the energy-ray curable compound can be formed. By using adhesive composition (I-2), an adhesive layer containing the adhesive resin (I-2a) can be formed. By using the adhesive composition (I-3), an adhesive layer containing an adhesive resin (I-2a) and an energy ray curable compound can be formed.

[0089] Examples of non-energy ray curable adhesive compositions for forming a non-energy ray curable adhesive layer include adhesive composition (I-4) containing the adhesive resin (I-1a). By using adhesive composition (I-4), an adhesive layer containing the adhesive resin (I-1a) can be formed.

[0090] The adhesive layer and adhesive compositions (I-1), (I-2), and (I-3) (hereinafter, these adhesive compositions will be collectively abbreviated as "adhesive compositions (I-1) to (I-3)") may further contain a photopolymerization initiator. The adhesive layer and adhesive compositions (I-1) to (I-3) containing a photopolymerization initiator will undergo a sufficient curing reaction even when irradiated with relatively low-energy rays such as ultraviolet light. The adhesive compositions (I-1), (I-2), (I-3), and (I-4) (hereinafter, these adhesive compositions will be collectively abbreviated as "adhesive compositions (I-1) to (I-4)") may contain a solvent. Adhesive compositions (I-1) to (I-4) containing a solvent have high coating suitability for the surface to be coated.

[0091] The adhesive layer and the adhesive composition (I-1), (I-2), (I-3), or (I-4) each contain one or more adhesive resins (I-1a), (I-2a), energy ray curable compound, photopolymerization initiator, and solvent, and if there are two or more, their combination and ratio can be arbitrarily selected.

[0092] [Adhesive resin (I-1a)] The adhesive resin (I-1a) is preferably an acrylic resin. In the adhesive layer and adhesive compositions (I-1) to (I-4), the constituent units of the acrylic resin may be only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0093] Examples of the acrylic resin include acrylic polymers having at least one structural unit derived from an alkyl (meth)acrylate. Examples of the alkyl (meth)acrylate include those in which the alkyl group constituting the alkyl ester has 1 to 20 carbon atoms.

[0094] In this specification, "(meth)acrylic acid" is a concept that encompasses both "acrylic acid" and "methacrylic acid." The same applies to terms similar to (meth)acrylic acid.

[0095] The acrylic polymer preferably has, in addition to structural units derived from alkyl (meth)acrylate esters, structural units derived from functional group-containing monomers. Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and the like.

[0096] The acrylic polymer may or may not have structural units derived from other monomers, in addition to structural units derived from alkyl (meth)acrylate and structural units derived from functional group-containing monomers. The other monomers are not particularly limited as long as they can be copolymerized with alkyl (meth)acrylate, etc., and specific examples include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide, and the like.

[0097] In the acrylic polymer, the ratio of the content of constituent units derived from alkyl (meth)acrylate to the total amount of constituent units is preferably 1 to 97% by mass, and may be, for example, 30 to 95% by mass, 50 to 93% by mass, or 70 to 90% by mass.

[0098] In the acrylic polymer, the ratio of the content of functional group-containing monomer-derived structural units to the total amount of structural units is preferably 3 to 99% by mass, and may be, for example, 5 to 70% by mass, 7 to 50% by mass, or 10 to 30% by mass.

[0099] In the acrylic polymer, the ratio of the content of constituent units derived from other monomers to the total amount of constituent units is preferably 0 to 10% by mass, and may be, for example, 0 to 7% by mass, 0 to 5% by mass, or 0 to 3% by mass.

[0100] However, in the acrylic polymer, the total content ratio of constituent units derived from alkyl (meth)acrylate, constituent units derived from functional group-containing monomers, and constituent units derived from other monomers, relative to the total amount of constituent units, shall not exceed 100% by mass.

[0101] In adhesive compositions (I-1) or (I-4), the ratio of the content of adhesive resin (I-1a) to the total content of components other than the solvent is preferably 5 to 99% by mass. This is equivalent to saying that in the adhesive layer formed from adhesive composition (I-1) or (I-4), the ratio of the content of adhesive resin (I-1a) to the total mass of the adhesive layer is preferably 5 to 99% by mass. This is based on the fact that in the process of removing the solvent from a solvent-containing resin composition to form a resin film, the amount of components other than the solvent usually does not change, and the ratio of the content of components other than the solvent is the same in the resin composition and the resin film. The same applies to other components described later that are not adhesive resin (I-1a) or solvent contained in adhesive composition (I-1) or (I-4), and the same applies to other components described later that are not solvent contained in adhesive composition (I-2) or (I-3).

[0102] [Adhesive resin (I-2a)] The adhesive resin (I-2a) in the adhesive compositions (I-2) and (I-3) can be obtained, for example, by reacting a functional group in the adhesive resin (I-1a) with an unsaturated group-containing compound having an energy-ray polymerizable unsaturated group.

[0103] The unsaturated group-containing compound has, in addition to the energy-ray polymerizable unsaturated group, a reactive group that can bond to the adhesive resin (I-1a) by reacting with the functional group in the adhesive resin (I-1a). Examples of the energy-ray polymerizable unsaturated group include groups having a carbon-carbon double bond (C=C), such as a (meth)acryloyl group, a vinyl group (ethenyl group), and an allyl group (2-propenyl group), with the (meth)acryloyl group being preferred.

[0104] The number of double bonds between carbon atoms in one molecule of the unsaturated group-containing compound is preferably 1 to 5, and may be, for example, 1 to 4, 1 to 3, or 1 to 2.

[0105] Examples of the reactive groups include isocyanate groups and glycidyl groups that can be bonded to hydroxyl groups or amino groups, and hydroxyl groups, amino groups, and aziridinyl groups that can be bonded to carboxyl groups or epoxy groups.

[0106] Examples of the unsaturated group-containing compounds include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

[0107] Examples of adhesive resins (I-2a) include those in which, when the functional groups in the adhesive resin (I-1a) react with the reactive groups in the unsaturated group-containing compound, the total number of moles of the reactive groups is preferably 0.1 to 1 times the total number of moles of the functional groups, for example, 0.3 to 0.95 times, 0.5 to 0.9 times, and 0.7 to 0.85 times.

[0108] The weight-average molecular weight (Mw) of the adhesive resin (I-2a) is preferably 150,000 to 1,500,000, and may be, for example, 200,000 to 1,000,000 or 250,000 to 750,000. By using such an adhesive resin (I-2a), it becomes easier to adjust the infrared (1600 nm) transmittance of the bonded sheet and the peeling force to the above range.

[0109] In this specification, not only in the case of adhesive resins (I-2a), but unless otherwise specified, "weight-average molecular weight" refers to the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0110] An example of a preferred adhesive resin (I-2a) is an adhesive resin (I-2a) having a structure obtained by reacting the functional groups in an acrylic polymer having structural units derived from (meth)acrylate and structural units derived from functional group-containing monomers with the reactive groups in an unsaturated group-containing compound having energy-ray polymerizable unsaturated groups and reactive groups that can react with the functional groups. In such an adhesive resin (I-2a), it is preferable that the ratio of structural units derived from (meth)acrylate to the total amount of structural units in the acrylic polymer is 1 to 97% by mass, and the ratio of structural units derived from functional group-containing monomers to the total amount of structural units is 3 to 99% by mass. In such an adhesive resin (I-2a), it is preferable that the total number of moles of the reactive groups in the unsaturated group-containing compound is 0.3 to 0.95 times the total number of moles of the functional groups in the acrylic polymer.

[0111] In the adhesive composition (I-2) or (I-3), the ratio of the content of the adhesive resin (I-2a) to the total content of components other than the solvent is preferably 20 to 99% by mass, and may be, for example, 40 to 99% by mass, 60 to 99% by mass, or 80 to 99% by mass.

[0112] [Energy-ray curable compounds] Examples of energy-ray curable compounds include monomers or oligomers having an energy-ray polymerizable unsaturated group that can be cured by irradiation with energy rays.

[0113] Examples of monomers among energy-ray curable compounds include polyvalent (meth)acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate; urethane (meth)acrylate; polyester (meth)acrylate; polyether (meth)acrylate; and epoxy (meth)acrylate. Examples of oligomers among energy-ray curable compounds include oligomers having a structure formed by the polymerization of the monomers exemplified above.

[0114] In the adhesive composition (I-1) and the adhesive layer formed using the same, the content of the energy ray curable compound is preferably 10 to 150 parts by mass per 100 parts by mass of the content of the adhesive resin (I-1a), for example, it may be 25 to 100 parts by mass. In the adhesive composition (I-3) and the adhesive layer formed using the same, the content of the energy ray curable compound is preferably 10 to 150 parts by mass per 100 parts by mass of the content of the adhesive resin (I-2a), for example, it may be 25 to 100 parts by mass.

[0115] [Crosslinking agent] When the acrylic polymer having structural units derived from functional group-containing monomers in addition to structural units derived from alkyl (meth)acrylate is used as the adhesive resin (I-1a), it is preferable that the adhesive composition (I-1) or (I-4) further contains a crosslinking agent. When the acrylic polymer having structural units derived from functional group-containing monomers, similar to those in the adhesive resin (I-1a), is used as the adhesive resin (I-2a), the adhesive composition (I-2) or (I-3) may further contain a crosslinking agent. The crosslinking agent reacts, for example, with the functional groups to crosslink the adhesive resins (I-1a) with each other or with each other.

[0116] Examples of crosslinking agents include isocyanate-based crosslinking agents (crosslinking agents having an isocyanate group) such as tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and adducts of these diisocyanates; epoxy-based crosslinking agents (crosslinking agents having a glycidyl group) such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents (crosslinking agents having an aziridinyl group) such as hexa[1-(2-methyl)-aziridinyl]triphosphotriazine; metal chelate-based crosslinking agents (crosslinking agents having a metal chelate structure) such as aluminum chelate; and isocyanurate-based crosslinking agents (crosslinking agents having an isocyanuric acid skeleton).

[0117] The crosslinking agents contained in the adhesive layer and the adhesive compositions (I-1) to (I-4) may consist of only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0118] When a crosslinking agent is used, the content of the crosslinking agent in the adhesive composition (I-1) or (I-4) and the adhesive layer formed using these is preferably 0.01 to 40 parts by mass per 100 parts by mass of the adhesive resin (I-1a), for example, it may be any of 0.01 to 30 parts by mass and 0.01 to 20 parts by mass. When a crosslinking agent is used, the content of the crosslinking agent in the adhesive composition (I-2) or (I-3) and the adhesive layer formed using these is preferably 0.01 to 40 parts by mass per 100 parts by mass of the adhesive resin (I-2a), for example, it may be any of 0.01 to 30 parts by mass, 0.01 to 20 parts by mass, 0.01 to 10 parts by mass and 0.01 to 5 parts by mass.

[0119] [Photopolymerization initiator] The adhesive layer containing a photopolymerization initiator, and the adhesive compositions (I-1) to (I-3), undergo sufficient curing reaction even when irradiated with relatively low-energy rays such as ultraviolet light.

[0120] Examples of photopolymerization initiators include α-ketol compounds such as 1-hydroxycyclohexylphenyl ketone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, and benzoin dimethyl ketal; acetophenone compounds such as acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and sulfide compounds such as benzylphenyl sulfide and tetramethylthiuram monosulfide. Examples include azo compounds such as azobisisobutyronitrile; titanocene compounds such as titanocene; thioxanthone compounds such as thioxanthone; peroxide compounds; diketone compounds such as diacetyl; benzyl; dibenzyl; benzophenone; 2,4-diethylthioxanthone; 1,2-diphenylmethane; 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone; quinone compounds such as 1-chloroanthraquinone and 2-chloroanthraquinone; and photosensitizers such as amines.

[0121] The photopolymerization initiator contained in the adhesive layer and the adhesive compositions (I-1) to (I-3) may be one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0122] In the adhesive composition (I-1) and the adhesive layer formed using the same, the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass per 100 parts by mass of the content of the energy ray curable compound, for example, it may be 0.1 to 10 parts by mass and 0.5 to 6 parts by mass. In the adhesive composition (I-2) and the adhesive layer formed using the same, the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass per 100 parts by mass of the content of the adhesive resin (I-2a), for example, it may be 0.1 to 10 parts by mass and 0.5 to 6 parts by mass. In the adhesive composition (I-3) and the adhesive layer formed using the same, the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass per 100 parts by mass of the total content of the adhesive resin (I-2a) and the energy ray curable compound, for example, it may be 0.1 to 10 parts by mass and 0.5 to 6 parts by mass.

[0123] [Solvent] The adhesive compositions (I-1) to (I-4) containing a solvent exhibit high suitability for coating the target surface.

[0124] In this specification, unless otherwise specified, the term "solvent" includes not only substances that dissolve the target component but also dispersion media that disperse the target component.

[0125] The solvent is preferably an organic solvent, and examples of such organic solvents include ketones such as methyl ethyl ketone and acetone; esters (carboxylic acid esters) such as ethyl acetate; ethers such as tetrahydrofuran and dioxane; aliphatic hydrocarbons such as cyclohexane and n-hexane; aromatic hydrocarbons such as toluene and xylene; and alcohols such as 1-propanol and 2-propanol.

[0126] The solvent content of adhesive compositions (I-1) to (I-4) is not particularly limited and may be adjusted as appropriate.

[0127] [Other Additives] The adhesive layer and adhesive compositions (I-1) to (I-4) may contain, or may not contain, other additives that do not fall under any of the above-mentioned components, as long as they do not impair the effects of the present invention. Examples of such other additives include known additives such as antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, colorants (pigments, dyes), sensitizers, tackifiers, reaction retarders, and crosslinking accelerators (catalysts). However, in order to further increase the infrared (1600 nm) transmittance of the bonded sheet, it is preferable that the adhesive layer does not contain fillers and colorants, or if it contains either of these, the content is at a low level. The reaction retarder is, for example, a component that suppresses the progress of unintended crosslinking reactions in adhesive compositions (I-1) to (I-4) during storage due to the action of a catalyst mixed in the adhesive compositions (I-1) to (I-4).

[0128] The adhesive layer and the other additives contained in the adhesive compositions (I-1) to (I-4) may consist of only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0129] The content of the adhesive layer and other additives in the adhesive compositions (I-1) to (I-4) is not particularly limited and may be appropriately selected depending on their type.

[0130] <Example of an adhesive layer> An example of a preferred adhesive layer formed using the adhesive composition (I-2) is an adhesive layer containing an adhesive resin (I-2a) and a crosslinking agent, wherein the adhesive resin (I-2a) has a structure obtained by reacting a functional group in an acrylic polymer having structural units derived from (meth)acrylate and structural units derived from a functional group-containing monomer with an energy-ray polymerizable unsaturated group and a reactive group that can react with the functional group, wherein in the acrylic polymer, the ratio of the content of structural units derived from (meth)acrylate to the total amount of structural units is 1 to 97% by mass, and the ratio of the content of structural units derived from the functional group-containing monomer to the total amount of structural units is 3 to 99% by mass, provided that in the acrylic polymer, the total content ratio of structural units derived from (meth)acrylate and structural units derived from the functional group-containing monomer to the total amount of structural units does not exceed 100% by mass. An example of an adhesive layer is one in which the total number of moles of the reactive groups in the unsaturated group-containing compound is 0.3 to 0.95 times the total number of moles of the functional groups in the acrylic polymer, the ratio of the content of the adhesive resin (I-2a) to the total mass of the adhesive layer is 20 to 99% by mass, and the content of the crosslinking agent in the adhesive layer is 0.01 to 40 parts by mass per 100 parts by mass of the content of the adhesive resin (I-2a), provided that the ratio of the combined content of the adhesive resin (I-2a) and the crosslinking agent to the total mass of the adhesive layer does not exceed 100% by mass.

[0131] Such an adhesive layer further contains a photopolymerization initiator, wherein the content of the photopolymerization initiator in the adhesive layer is 0.01 to 20 parts by mass per 100 parts by mass of the adhesive resin (I-2a), provided that, in the adhesive layer, the ratio of the total content of the adhesive resin (I-2a), the crosslinking agent, and the photopolymerization initiator to the total mass of the adhesive layer does not exceed 100% by mass.

[0132] <Method for Producing Adhesive Compositions> Adhesive compositions such as (I-1) to (I-4) are obtained by blending the adhesive with other components, as needed, to constitute the adhesive composition. The order in which the components are added is not particularly limited, and two or more components may be added simultaneously. The method of mixing the components during blending is not particularly limited, and can be appropriately selected from known methods such as mixing by rotating a stirring bar or stirring blade, mixing using a mixer, or mixing by applying ultrasonic waves. The temperature and time during the addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and can be adjusted as appropriate, but the temperature is preferably 15 to 30°C.

[0133] <Other configurations of the adhesive layer> The adhesive layer may consist of one layer (single layer) or of two or more layers. When the adhesive layer consists of multiple layers, these layers may be identical or different from each other, and the combination of these layers is not particularly limited. In this embodiment, a single adhesive layer is usually sufficient.

[0134] The thickness of the adhesive layer is preferably 1 to 50 μm, and may be, for example, 2 to 30 μm or 3 to 20 μm. When the thickness of the adhesive layer is greater than or equal to the lower limit, the strength of the adhesive layer is increased, the uniformity of the thickness of the adhesive layer is increased, and the adhesion of the adhesive layer to the object to be bonded is increased. When the thickness of the adhesive layer is less than or equal to the upper limit, the infrared (1600 nm) transmittance of the bonded sheet is increased.

[0135] <<Release Film>> The release film may be a known type, for example, one or both sides of a release film substrate being a release surface.

[0136] <<Other Layers>> The type, number, thickness, and placement of the other layers are not particularly limited, as long as they do not impair the effects of the present invention. However, it is preferable that the bonding sheet of this embodiment does not have the other layers on the second surface of the base material.

[0137] ◇Method for Manufacturing the Bonded Sheet The bonded sheet of this embodiment can be manufactured by laminating the above-mentioned layers in corresponding positional relationships and, if necessary, adjusting the shape of some or all of the layers. The method for forming each layer is as described above. The bonded sheet of this embodiment can be manufactured in the same way as conventional bonded sheets, except that, in order to achieve the above-mentioned infrared (1600 nm) transmittance and peeling strength, a specially adjusted substrate or the resin composition for forming the substrate and / or the adhesive composition are used.

[0138] For example, when laminating an adhesive layer onto a substrate, an adhesive composition is applied to a release film and dried as necessary to form an adhesive layer on the release film. Then, the exposed surface of this adhesive layer is bonded to one side of the substrate.

[0139] ◇Method for Manufacturing a Semiconductor Device The method for manufacturing a semiconductor device according to one embodiment of the present invention is a method for using a bonding sheet according to the above-described embodiment of the present invention, wherein a semiconductor chip is used as the workpiece and a circuit board is used as the target object, and after peeling the bonding sheet from the semiconductor chip bonded to the circuit board, a semiconductor device is manufactured using the circuit board to which the semiconductor chip is bonded.

[0140] In other words, in the semiconductor device manufacturing method of this embodiment, a semiconductor chip is provided on the side of the adhesive layer in the bonding sheet opposite to the side of the substrate, the side of the semiconductor chip opposite to the side of the bonding sheet (circuit side) is placed opposite to one side (circuit side) of the circuit board, the semiconductor chip is aligned with the circuit board while observing the circuit board through the bonding sheet, the aligned semiconductor chip is pressed against the circuit board through the bonding sheet to bring the semiconductor chip into direct contact with the circuit board and bonded, and if the adhesive layer is energy ray curable, energy rays are irradiated onto the adhesive layer at some point between providing the semiconductor chip on the bonding sheet and bonding the semiconductor chip to the circuit board to make the adhesive layer an energy ray cured product. By releasing the pressure on the semiconductor chip, if the adhesive layer is energy-ray curable, the energy-ray cured portion of the adhesive layer is peeled off from the semiconductor chip bonded to the circuit board; if the adhesive layer is not energy-ray curable, the adhesive layer is peeled off from the semiconductor chip bonded to the circuit board, thereby peeling off the bonding sheet from the semiconductor chip, and a circuit board to which the semiconductor chip is bonded is obtained. By applying the method of using the bonding sheet, the circuit surface of a semiconductor chip without protruding electrodes can be directly bonded (mounted) to the circuit surface of a circuit board.

[0141] The method for manufacturing a semiconductor device in this embodiment may be the same as known methods for manufacturing a semiconductor device, except that a circuit board on which semiconductor chips are bonded is manufactured using the bonding sheet method described above, and then this circuit board on which semiconductor chips are bonded is used.

[0142] The present invention will be described in more detail below with reference to specific examples. However, the present invention is not limited in any way to the examples shown below.

[0143] [Example 1] <<Production of bonding sheet>> <Production of adhesive composition (I-2)> An acrylic polymer (adhesive resin (I-1a)) which is a copolymer of 2-ethylhexyl acrylate (2EHA) (80 parts by mass) and 2-hydroxyethyl acrylate (HEA) (20 parts by mass) was mixed with 2-methacryloyloxyethyl isocyanate (MOI) (in an amount such that the total number of isocyanate groups in MOI is 0.8 times the total number of moles of hydroxyl groups derived from HEA in the acrylic polymer), and an addition reaction was carried out at 50°C for 48 hours under an air atmosphere to obtain the target adhesive resin (I-2a)-1 (weight-average molecular weight 500,000).

[0144] An energy-ray curable adhesive composition (I-2)-1 was prepared, containing an adhesive resin (I-2a)-1 (100 parts by mass), a tolylene diisocyanate-based crosslinking agent (Tosoh Corporation's "Coronate L") (1 part by mass), and a photopolymerization initiator (BASF's "Irgacure 184", 1-hydroxycyclohexylphenyl ketone) (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the content of components other than methyl ethyl ketone shown herein is the content of the target product excluding the solvent.

[0145] <Manufacturing of Substrate> An LDPE film was produced by extruding a resin composition made of low-density polyethylene (LDPE) using a small T-die extruder (Laboplastmill, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Immediately after production, one side of the LDPE film was brought into contact with the surface of a cooled roll, and the LDPE film was passed over the roll to adjust the roughness of one side of the LDPE film. In this way, an LDPE substrate (bm1) with a thickness of 80 μm was produced.

[0146] Using a contact-type surface roughness meter (Mitutoyo SV3000S4), the arithmetic mean roughness (Ra) and maximum height roughness (Rz) were calculated in accordance with JIS B 0601:2013 on the surface of the substrate (bm1) obtained above, under the following conditions. The results are shown in Table 1. [Roughness Measurement Conditions] Evaluation length: 10 mm Reference length: 2.5 mm Scanning speed: 1.0 mm / s Cutoff value: 0.25 mm

[0147] <Manufacturing of Bonded Sheet> A release film (Lintec Corporation's "SP-PET381031", 38 μm thick) made of polyethylene terephthalate film, with one side of which was peel-treated by silicone, was used. The adhesive composition (I-2)-1 obtained above was applied to the peel-treated surface and heated and dried at 100°C for 2 minutes to form an energy-ray curable adhesive layer (AL1) with a thickness of 10 μm. Next, the surface of the substrate (bm1) obtained above, opposite to the side where Ra and Rz were adjusted (measured), was bonded to the exposed surface of this adhesive layer (AL1). Thus, the substrate, the adhesive layer, and the release film were laminated in this order in the thickness direction, and a bonded sheet with a release film was obtained in which the Ra and Rz of the exposed surface of the substrate were the values ​​described above.

[0148] <<Evaluation of Bonded Sheet>> <Measurement of Infrared (1600nm) Transmittance> In the bonded sheet obtained above, the release film was removed, and the infrared (1600nm) transmittance was measured by irradiating the bonded sheet with infrared light (1600nm) from the substrate side using a spectrophotometer (Shimadzu Corporation "UV-VIS-NIR SPECTROPHOTOMETER UV-3600") under the following measurement conditions. The results are shown in Table 1. [Transmittance Measurement Conditions] Wavelength range: 190-2000nm Scan speed: High speed Slit width: 8.0mm Detector unit: Direct light reception

[0149] <Evaluation of Alignment Mark Recognition Performance> An 8-inch silicon wafer was diced using a dicing sheet (Lintec Corporation "D-485H") to create a group of silicon chips with a dicing sheet, in which numerous silicon chips, each 150 μm thick and 6 mm x 6 mm in size, were arranged spaced apart from each other on the dicing sheet. In this case, the silicon wafer used had a dry-polished surface on the side opposite the circuit surface, and the silicon wafer was diced with the circuit surface side attached to the dicing sheet. Using a desktop laminator, the adhesive layer from the single bonding sheet obtained above was applied to the exposed surface (ground surface) of all silicon chips in the group of silicon chips with a dicing sheet at a bonding speed of 0.6 mm / min. Furthermore, all silicon chips on the dicing sheet were transferred to the bonding sheet by removing the dicing sheet from all the silicon chips. As a result, a group of silicon chips with a bonding sheet was obtained, comprising a bonding sheet and a number of silicon chips arranged on the bonding sheet at intervals from each other.

[0150] Using a parallel plate reactive ion etching apparatus (Samco "RIE-10NR"), the exposed surfaces (circuit surfaces) of all silicon chips in the group of silicon chips with bonding sheets were modified by irradiating them with plasma under the following irradiation conditions. A silicon wafer (thickness 750 μm, size 8 inches) to be bonded to the silicon chips was prepared, and its circuit surface was modified by irradiating it with plasma under the same conditions as for the silicon chips. [Plasma irradiation conditions] Nitrogen gas flow rate: 100 mL Output: 200 W Irradiation time: 60 seconds

[0151] The silicon chip group with a bonding sheet and the silicon wafer were arranged facing each other by facing the modified exposed surface of the silicon chips in the silicon chip group with a bonding sheet and the modified circuit surface of the silicon wafer with a space between them. In this state, an infrared camera was arranged on the side opposite to the side of the silicon wafer with respect to the silicon chip group with a bonding sheet. Then, the modified circuit surface of the silicon wafer was observed through the bonding sheet from the infrared camera, and the availability of recognition of the alignment marks provided thereon was confirmed. And when the alignment marks could be recognized, the recognition performance was determined as "A", and when they could not be recognized, the recognition performance was determined as "B". The results are shown in Table 1.

[0152] <Evaluation of the peeling performance from the work workpiece> After the evaluation of the recognition performance of the above alignment marks, it was confirmed that the silicon chips in the silicon chip group with a bonding sheet were arranged at appropriate positions with respect to the modified circuit surface of the silicon wafer. Next, using an ultraviolet irradiation device ("RAD-2010m / 12" manufactured by Rintec Co., Ltd.), ultraviolet rays were irradiated through a substrate to the adhesive layer in the bonding sheet under the conditions of an illuminance of 230 mW / cm ２ , a light quantity of 190 mJ / cm ２ to cure the adhesive layer with ultraviolet rays. Next, at room temperature, using a pressing jig of the same size as the silicon chip, the silicon chip was pressed against the silicon wafer through the bonding sheet from the side opposite to the side of the silicon wafer to be joined, so that the silicon chip was adhered to and joined to the silicon wafer. At this time, the pressing pressure was 5 N per silicon chip, and the pressing time was 0.5 seconds. Next, the pressing of the silicon chip was released, and the presence or absence of peeling of the bonding sheet from the silicon chip at this stage was visually observed. And when the bonding sheet was peeled from the silicon chip, the peeling performance was determined as "A", and when it was not peeled, the peeling performance was determined as "B". The results are shown in Table 1.

[0153] <Measurement of peeling force between the energy ray irradiated object of the adhesive layer and the silicon chip> Similar to the evaluation of the recognition performance of the alignment marks described above, a group of silicon chips with bonding sheets was prepared. The adhesive layer of the obtained group of silicon chips with bonding sheets was irradiated with the ultraviolet irradiation device at an illuminance of 230 mW / cm². ２ , light intensity 190mJ / cm ２ Under the specified conditions, a test specimen was prepared by irradiating the substrate with energy rays from the outside of the substrate side, through the substrate, to cure the adhesive layer with energy rays. Using a pickup strength measuring device, the peel force between the energy-ray-cured material and the silicon chip was measured when, in the test specimen, a silicon chip was pushed up through the bonding sheet by five pins from the outside of the substrate side under the conditions of a push-up height of 200 μm, a push-up speed of 10 mm / s, and a push-up time of 100 ms, and the silicon chip was picked up by pulling it away from the energy-ray-cured material of the adhesive layer in the direction of the push-up by the pins. This peel force measurement was performed on 10 arbitrarily selected silicon chips, and the average of the obtained 10 measurements was formally adopted as the peel force between the energy-ray-cured material and the silicon chip. The results are shown in Table 1.

[0154] <<Manufacturing and Evaluation of Bonded Sheets>> [Examples 2-3] Except for using a resin composition made of polyvinyl chloride (PVC) instead of a resin composition made of low-density polyethylene (Example 2), or using a resin composition made of ethylene-methacrylic acid copolymer (EMAA) (Example 3), 80 μm thick PVC substrates (bm2) (Example 2) or EMAA substrates (bm3) (Example 3) were prepared in the same manner as in Example 1. The Ra and Rz values ​​of the roughness-adjusted surfaces of these substrates, measured in the same manner as in Example 1, are shown in Table 1. Then, except for using these substrates instead of substrate (bm1), bonded sheets were manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0155] [Comparative Example 1] An EMAA substrate (bmR1) with a thickness of 80 μm was prepared in the same manner as in Example 3, except that the roughness of one side of the EMAA film was adjusted by using rolls with different surface conditions. The Ra and Rz values ​​of the roughness-adjusted side of this substrate, measured in the same manner as in Example 1, are shown in Table 1. Then, a bonded sheet was manufactured and evaluated in the same manner as in Example 1, except that this substrate (bmR1) was used instead of the substrate (bm1). The results are shown in Table 1.

[0156] [Comparative Examples 2-3] Except for using rolls with different surface conditions to adjust the roughness of one side of the LDPE film, LDPE substrates (bmR2) (Comparative Example 2) or LDPE substrates (bmR3) (Comparative Example 3) with a thickness of 80 μm were prepared in the same manner as in Example 1. The Ra and Rz values ​​of the roughened sides of these substrates, measured in the same manner as in Example 1, are shown in Table 1 or Table 2. Then, bonded sheets were manufactured and evaluated in the same manner as in Example 1, except that these substrates were used instead of substrate (bm1). The results are shown in Table 1 or Table 2.

[0157] [Comparative Example 4] An energy-ray curable adhesive composition (IR)-1 was prepared, containing an acrylic polymer (weight-average molecular weight 500,000) (100 parts by mass) which is a copolymer of butyl acrylate (BA) (80 parts by mass) and HEA (20 parts by mass), urethane acrylate (Dainichi Seika Kogyo Co., Ltd. "EXL810TL", energy-ray curable resin, 3 functional groups, weight-average molecular weight 5,000) (70 parts by mass), a tolylene diisocyanate crosslinking agent (Tosoh Corporation "Coronate L") (1 part by mass), and a photopolymerization initiator (IGM Resins B.V. "Omnirad 184", 1-hydroxycyclohexylphenyl ketone) (3 parts by mass), and further containing methyl ethyl ketone as a solvent, with the total concentration of all components other than the solvent being 25% by mass. Note that the content of components other than methyl ethyl ketone shown here represents the content of the target substance without the solvent.

[0158] Except for using the adhesive composition (IR)-1 obtained above instead of adhesive composition (I-2)-1, a bonded sheet was manufactured by forming an energy-ray curable adhesive layer (ALR1) with a thickness of 10 μm, in the same manner as in Example 1. The obtained bonded sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0159] [Comparative Example 5] Except for using adhesive composition (IR)-1 instead of adhesive composition (I-2)-1, an energy-ray curable adhesive layer (ALR1) with a thickness of 10 μm was formed and a bonded sheet was manufactured in the same manner as in Example 2. The obtained bonded sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0160] [Comparative Example 6] Except for using adhesive composition (IR)-1 instead of adhesive composition (I-2)-1, an energy-ray curable adhesive layer (ALR1) with a thickness of 10 μm was formed and a bonded sheet was manufactured in the same manner as in Example 3. The obtained bonded sheet was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0161]

[0162]

[0163] As is clear from the above results, in Examples 1 to 3, alignment marks on the silicon wafer could be recognized through the bonding sheet, and the silicon chip could be aligned with the silicon wafer through the bonding sheet. In Examples 1 to 3, the infrared (1600 nm) transmittance of the bonding sheet was 90% or more.

[0164] Furthermore, in Examples 1 to 3, the bonding sheet could be peeled off from all silicon chips after bonding to the silicon wafer. In Examples 1 to 3, the peeling force was 3.4 N or less.

[0165] In Examples 1 to 3, the Ra of the exposed surface of the substrate was 0.03 μm or less, and the Rz was 0.24 μm or less.

[0166] In contrast, in Comparative Examples 1 to 3, alignment marks on the silicon wafer could not be recognized through the bonding sheet, and the silicon chip could not be aligned with the silicon wafer through the bonding sheet; therefore, other methods were required for alignment. In Comparative Examples 1 to 3, the infrared (1600 nm) transmittance of the bonding sheet was 42% or less. In Comparative Examples 1 to 3, the adhesive layer in the bonding sheet was the same as in Examples 1 to 3 (adhesive layer (AL1)), but the substrate was different from that in Examples 1 to 3 (substrate (bmR1) to substrate (bmR3)).

[0167] In Comparative Examples 4 to 6, the bonding sheet could not be peeled off from at least one silicon chip after bonding to the silicon wafer. In Comparative Examples 4 to 6, the peeling force was greater than 5 N. In Comparative Examples 4 to 6, the substrate in the bonding sheet was the same as in Examples 1 to 3 (substrate (bm1) to substrate (bm3)), but the adhesive layer was different from that in Examples 1 to 3 (adhesive layer (ALR1)).

[0168] This invention can be used for joining workpieces that do not have protruding electrodes to an object.

[0169] 101...Bonding sheet 11...Substrate, 11a...One side of the substrate 12...Adhesive layer, 12a...Side of the adhesive layer opposite to the substrate side (first side)

Claims

1. A bonding sheet comprising a base material and an adhesive layer provided on one surface of the base material, wherein the bonding sheet is used to bond a workpiece to an object by holding the workpiece on the side of the adhesive layer opposite to the base material side, and bringing the side of the workpiece opposite to the bonding sheet side into direct contact with the object, wherein the transmittance of the infrared light measured by irradiating the bonding sheet with infrared light of a wavelength of 1600 nm from outside the side of the base material is 80% or more, and the adhesive layer in the bonding sheet is applied to a silicon chip with a thickness of 150 μm and dimensions of 6 mm x 6 mm at room temperature at an application speed of 0.6 mm / min, and the illuminance of the adhesive layer is 230 mW / cm². ２ , light intensity 190mJ / cm ２ A bonded sheet is prepared by irradiating the silicon chip with energy rays under the following conditions, thereby creating a laminate of the silicon chip, the energy-irradiated object of the adhesive layer, and the substrate; and in the test piece, the silicon chip is pushed up with a pin from the outside of the substrate side under the conditions of a push-up height of 200 μm, a push-up speed of 10 mm / s, and a push-up time of 100 ms, and the silicon chip is picked up by pulling it away from the energy-irradiated object of the adhesive layer in the direction of the push-up by the pin, and the peel force between the energy-irradiated object of the adhesive layer and the silicon chip is measured to be 5 N or less.

2. The bonding sheet according to claim 1, wherein the peeling force is 0.01 N or more.

3. The bonding sheet according to claim 1 or 2, wherein the object is a wafer.

4. The bonding sheet according to claim 1 or 2, wherein the bonding surface of the workpiece with the object and the bonding surface of the object with the workpiece are modified.

5. The bonding sheet according to claim 4, wherein all of the bonding surfaces are modified by plasma treatment or ozone treatment.

6. A method for using the bonding sheet according to claim 1 or 2, wherein in the method of use, a workpiece is placed on the side of the adhesive layer in the bonding sheet opposite to the side of the substrate, the side of the workpiece opposite to the side of the bonding sheet is placed opposite to one side of the object to be bonded, the workpiece is aligned with the object while observing the object through the bonding sheet, the aligned workpiece is pressed against the object through the bonding sheet to bond the workpiece to the object by bringing it into direct contact with the object, and if the adhesive layer is energy ray curable, energy rays are irradiated onto the adhesive layer at any time between placing the workpiece on the bonding sheet and bonding the workpiece to the object to make the adhesive layer energy ray cured. A method for using a bonding sheet, wherein if the adhesive layer is energy-ray curable, the energy-ray cured portion of the adhesive layer is peeled off from the workpiece bonded to the object by releasing the pressure on the workpiece, and if the adhesive layer is not energy-ray curable, the bonding sheet is peeled off from the workpiece bonded to the object by peeling off the adhesive layer.

7. A method for using a bonding sheet according to claim 6, wherein a semiconductor chip is used as the workpiece and a circuit board is used as the target object, and after peeling the bonding sheet from the semiconductor chip bonded to the circuit board, a semiconductor device is manufactured using the circuit board to which the semiconductor chip is bonded.

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