JP7157861B1 - Semiconductor device manufacturing method - Google Patents

Abstract

Kind Code: A1 A method for manufacturing a semiconductor device is provided in which grinding can be performed without peeling off the peripheral portion of an object to be processed from a double-sided adhesive sheet, and the object to be processed is less likely to warp or break after grinding. A method for manufacturing a semiconductor device includes a first adhesive layer (X1) as an outer layer on one side and a second adhesive layer (X2) as an outer layer on the other side. Two pressure-sensitive adhesive layers use energy ray-curing double-sided pressure-sensitive adhesive sheet 1c, a support 3 having energy ray transparency is adhered to the first pressure-sensitive adhesive layer, and a wafer W is adhered to the second pressure-sensitive adhesive layer. In this state, a back surface grinding step of grinding the surface of the wafer W opposite to the surface attached to the second adhesive layer; Energy for curing the region X2q of the second adhesive layer by selectively starting to irradiate the region X2q corresponding to the portion Wq inside the peripheral edge Wp of the wafer W of the second adhesive layer with the energy beam. and a ray irradiation step. [Selection drawing] Fig. 4

Description

The present invention relates to a method of manufacturing a semiconductor device.

Adhesive sheets are used not only for semi-permanently fixing members, but also for processing and inspecting building materials, interior materials, electronic parts, etc. ) may be used as a temporary fixing sheet for temporarily fixing. For example, in the process of manufacturing semiconductor devices, temporary fixing sheets are used when processing semiconductor wafers.

In the process of manufacturing a semiconductor device, a semiconductor wafer undergoes a step of grinding its back surface to reduce its thickness (hereinafter also referred to as a "back grinding step"), a singulation step of cutting and separating into individual pieces, and the like. , are processed into semiconductor chips. At this time, the semiconductor wafer is subjected to a predetermined processing while being temporarily fixed to the temporary fixing sheet. After the semiconductor chips obtained by performing the predetermined processing are separated from the temporary fixing sheet, if necessary, an expanding step is performed to widen the gap between the semiconductor chips, and a re-arrangement of a plurality of semiconductor chips with widened gaps is performed. After an arrangement process, a reversing process for reversing the front and back of the semiconductor chip, and the like are appropriately performed, the semiconductor chip is mounted on the substrate.

In order to suppress vibration in the back grinding process, prior to the back grinding process, the back grinding tape for fixing the semiconductor wafer is irradiated with energy rays such as ultraviolet rays, and the adhesive layer to which the semiconductor wafer is attached is removed. is preferably cured. In particular, the so-called pre-dicing method (i.e., prior to the back grinding process, singulation pretreatment such as providing grooves on the circuit surface of the semiconductor wafer or providing a modified layer near the circuit surface inside the semiconductor wafer) is used. and splitting the semiconductor wafer along the parts that have undergone preliminary treatment in the back grinding process), the chips after the semiconductor wafer is split and separated into individual pieces tend to tilt due to vibration. , there is a concern that the chips may come into contact with each other. Therefore, when the pre-dicing method is employed, it is more effective to irradiate the energy beam before the back surface grinding step, as described in Patent Document 1, for example.

On the other hand, when the adhesive layer has been cured, there is a problem that the back grind tape is easily peeled off from the peripheral edge of the semiconductor wafer. In addition, since the chips on the periphery of the semiconductor wafer do not form a product and do not have circuits formed thereon, the adhesiveness to the adhesive layer to which the semiconductor wafer is adhered is low in the first place. Therefore, when the above-described pre-dicing method is employed, chips on the peripheral portion may scatter in the back-grinding process if the adhesive layer has already been cured.

Patent Literatures 1 and 2 describe that the peripheral region of a protective tape to be adhered to a semiconductor wafer is masked by a light shielding plate, and the protective tape is irradiated with ultraviolet rays. By masking the outer peripheral region and irradiating with ultraviolet rays, the adhesive layer in the outer peripheral region of the protective tape is not hardened and the adhesive strength is maintained. It is said that it is possible to prevent scrap chips present in the outer peripheral portion from peeling and scattering.

JP 2016-119370 A JP-A-2002-334857

However, as described in Patent Document 1, when the energy beam is irradiated before the back grinding process, the adhesive in the adhesive layer of the back grinding tape shrinks due to hardening, and the internal stress increases inside the adhesive. will be accumulated in Generally, the back grinding process is performed with the back grinding tape fixed by a fixing means such as a chuck table. However, when the back grinding tape and the semiconductor wafer are separated from the chuck table, the semiconductor wafer becomes thin. Therefore, internal stress is released, which causes warping of the wafer. The occurrence of warping becomes more pronounced as the thickness of the semiconductor wafer is reduced in the back grinding process.
When the above-mentioned pre-dicing method is adopted, releasing the internal stress causes positional deviation of the semiconductor chips, and there is a risk that the semiconductor chips may come into contact with each other during storage or transportation and be damaged.
In addition, when grooves are formed by the pre-dicing method, if the grooves are deep, the semiconductor wafer becomes fragile and easily damaged. Since there is no void, the shrinkage stress of the cured adhesive layer makes the problem that the corners of the semiconductor chips come into contact with adjacent semiconductor chips and break.

In addition, in the methods described in Patent Documents 1 and 2, since energy rays are irradiated through a mask, the adhesive layer under the mask (that is, the region corresponding to the peripheral edge of the semiconductor wafer) and the semiconductor wafer The hardness of the pressure-sensitive adhesive layer differs from that of the region corresponding to the inner side of the peripheral edge. As a result, the semiconductor wafer cannot be properly held, and grinding cannot be performed as intended in some cases.

As described above, the above-described problems cannot be avoided in the wafer processing methods described in Patent Documents 1 and 2.

The present invention has been made in view of the above problems, and even if the energy beam is irradiated before grinding the object to be processed to cure the adhesive layer to which the object to be processed is attached, the processing can be performed. To provide a method for manufacturing a semiconductor device in which the peripheral edge of an object can be ground as intended without peeling off from a double-sided adhesive sheet, and the object to be processed is less likely to warp or break after grinding. do.

The present inventors, in a state in which an object to be processed is supported by a support via a double-sided pressure-sensitive adhesive sheet having an energy ray-curable pressure-sensitive adhesive layer, before grinding the back surface of the object to be processed, the pressure-sensitive adhesive layer The inventors have found that the above-mentioned problems can be solved by selectively irradiating a specific portion of the body with an energy beam, and have completed the present invention.

That is, the present invention relates to the following [1] to [7].
[1] A first pressure-sensitive adhesive layer (X1) as an outer layer on one side and a second pressure-sensitive adhesive layer (X2) as an outer layer on the other side, wherein the second pressure-sensitive adhesive layer (X2) is Using a double-sided adhesive sheet with energy ray curability,
A support having energy ray transparency is attached to the first adhesive layer (X1), and an object to be processed is attached to the second adhesive layer (X2). a back surface grinding step of grinding the surface opposite to the surface attached to the agent layer (X2);
Before the back surface grinding step, on the second pressure-sensitive adhesive layer (X2) via the support and the first pressure-sensitive adhesive layer (X1), on the region corresponding to the part inside the peripheral edge of the object to be processed a method of manufacturing a semiconductor device, comprising an energy ray irradiation step of curing the region of the second adhesive layer (X2) by selectively starting irradiation of the energy ray.
[2] The double-sided pressure-sensitive adhesive sheet further comprises a base layer (Y), has a first pressure-sensitive adhesive layer (X1) on one main surface of the base layer, and has the other side of the base layer (Y). The method for manufacturing a semiconductor device according to the above [1], which has a second adhesive layer (X2) on the main surface of the above [1].
[3] The method for manufacturing a semiconductor device according to [2] above, wherein the substrate layer (Y) is a thermally expandable layer containing thermally expandable particles.
[4] The method for manufacturing a semiconductor device according to any one of [1] to [3] above, wherein the first adhesive layer (X1) is a thermally expandable layer containing thermally expandable particles.
[5] The above [3] or [4], wherein the support is separated from the first pressure-sensitive adhesive layer (X1) by heating the double-sided pressure-sensitive adhesive sheet after the energy beam irradiation step and the back surface grinding step. A method of manufacturing the semiconductor device described.
[6] As a preliminary step for singulation of the object to be processed,
A step of forming grooves, which are planned division lines, on the surface of the object to be processed on the side to be attached to the second adhesive layer (X2) before the back surface grinding step;
The method according to any one of the above [1] to [5], further comprising at least one of the step of forming a modified region, which is a line to be divided, inside the object before the back surface grinding step. A method of manufacturing the semiconductor device described.
[7] Any one of the above [1] to [6], wherein in the energy beam irradiation step, the energy beam is irradiated while masking a region of the support corresponding to the peripheral edge of the object to be processed. 2. The method of manufacturing the semiconductor device according to 1.

According to the present invention, there is provided a method for manufacturing a semiconductor device in which the peripheral portion of an object to be processed can be ground as intended without peeling off from the double-sided adhesive sheet, and the object to be processed is less likely to warp or break after grinding. can provide.

1 is a cross-sectional view showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention; FIG. FIG. 4 is a cross-sectional view showing another example of the configuration of the pressure-sensitive adhesive sheet of the present invention; It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention.

As used herein, the term “active ingredient” refers to the components contained in the target composition, excluding the diluent solvent.
Further, in the present specification, the mass average molecular weight (Mw) is a value converted to standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically a value measured based on the following procedure. be.
<Mass average molecular weight (Mw)>
Using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name “HLC-8020”), measurements were made under the following conditions, and the values measured in terms of standard polystyrene are used.
(Measurement condition)
・ Column: "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", "TSK gel G1000HXL" (both manufactured by Tosoh Corporation) are sequentially connected ・Column temperature: 40 ° C.
・Developing solvent: tetrahydrofuran ・Flow rate: 1.0 mL/min

In this specification, for example, "(meth)acrylic acid" indicates both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.
In addition, in this specification, the lower limit and upper limit values described stepwise for preferred numerical ranges (for example, ranges of content etc.) can be independently combined. For example, from the statement "preferably 10 to 90, more preferably 30 to 60", combining "preferred lower limit (10)" and "more preferred upper limit (60)" to "10 to 60" can also

As used herein, the term "energy ray" means an electromagnetic wave or charged particle beam that has an energy quantum, and examples thereof include ionizing radiation such as ultraviolet rays and gamma rays, and particle radiation such as electron beams. be done. Ultraviolet rays can be applied by using, for example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like as an ultraviolet light source. Among particle radiations, electron beams can be generated by an electron beam accelerator or the like.
As used herein, "energy ray-polymerizable" means the property of polymerizing by irradiation with energy rays. Moreover, in this specification, "energy ray-curable" means the property of polymerizing and curing by irradiation with an energy ray.

In this specification, whether a "layer" is a "non-thermally expandable layer" or a "thermally expandable layer" is determined as follows.
When the layer to be judged contains thermally expandable particles, the layer is heat-treated for 3 minutes at the expansion start temperature (t) of the thermally expandable particles. If the volume change rate calculated from the following formula is less than 5%, the layer is determined to be a "non-thermally expandable layer", and if it is 5% or more, the layer is a "thermally expandable layer". judge there is.
・Volume change rate (%) = {(volume of the layer after heat treatment - volume of the layer before heat treatment) / volume of the layer before heat treatment} x 100
A layer containing no thermally expandable particles is referred to as a "non-thermally expandable layer".

In this specification, the "front surface" of a semiconductor wafer and semiconductor chip refers to the surface on which circuits are formed (hereinafter also referred to as "circuit surface"), and the "back surface" of the semiconductor wafer and semiconductor chips refers to the surface on which circuits are formed. point to the side that is not

For the sake of convenience, the drawings used in the description of this specification are shown by enlarging or simplifying the main parts. Therefore, the dimensional ratio, number, etc. of each component are not necessarily the same as in reality. Also, in each figure, when there are a plurality of similar members, only representative ones may be given reference numerals.

[Method for manufacturing a semiconductor device]
In the method for manufacturing a semiconductor device according to an embodiment of the present invention, a first pressure-sensitive adhesive layer (X1) as an outer layer on one side and a second pressure-sensitive adhesive layer (X2) as an outer layer on the other side are provided, the second pressure-sensitive adhesive layer (X2) uses a double-sided pressure-sensitive adhesive sheet having energy ray curability,
With the support having energy ray transparency attached to the first adhesive layer (X1) and the object to be processed attached to the second adhesive layer (X2), the second adhesive of the object to be processed a back surface grinding step of grinding the surface opposite to the surface attached to the agent layer (X2);
Before the back surface grinding step, on the second pressure-sensitive adhesive layer (X2) via the support and the first pressure-sensitive adhesive layer (X1), to the region corresponding to the part inside the peripheral edge of the object to be processed and an energy beam irradiation step of curing the above region of the second pressure-sensitive adhesive layer (X2) by selectively starting irradiation with energy beams.

In this specification, the term "semiconductor device" refers to all devices that can function by utilizing semiconductor characteristics. For example, a wafer comprising integrated circuits, a thinned wafer comprising integrated circuits, a chip comprising integrated circuits, a thinned chip comprising integrated circuits, electronic components comprising these chips, and electronic equipment comprising such electronic components and the like.
Examples of the object to be processed include a semiconductor wafer, a collectively sealed body of a plurality of semiconductor chips, and the like.

In the above-described method for manufacturing a semiconductor device, the second adhesive layer (X2), which is the adhesive layer on the side to which the object to be processed is attached, uses a double-sided adhesive tape having energy ray-curable properties, An object to be processed is fixed to a support with a double-sided adhesive tape, and irradiation of energy rays is started selectively to a region corresponding to a portion inside the peripheral edge of the object to be processed. As a result, the semiconductor wafer or semiconductor chip is supported by the support until the semiconductor wafer is removed from the support or the semiconductor chip is separated from the support. ) is not affected by internal stress. Therefore, the workpiece is less likely to warp or break during or after grinding. Moreover, unlike the case where a backgrinding tape is used in place of the support, there is no problem that the backgrinding tape is flexed due to the singulation preparatory step and the handleability is deteriorated.

The back surface grinding step is a step of thinning the object by grinding the surface of the object opposite to the surface attached to the second pressure-sensitive adhesive layer (X2).
In the energy ray irradiation step, a specific region of the second pressure-sensitive adhesive layer (X2) is irradiated with an energy ray through the support and the first pressure-sensitive adhesive layer (X1), thereby forming a second pressure-sensitive adhesive layer (X2 ) to cure the above areas. Prior to grinding the object to be processed, the adhesive layer to which the object to be processed is attached is cured by irradiating the energy beam. becomes high. Therefore, sinking, vibration, movement, etc. of the object to be processed in the back grinding process can be effectively suppressed, and the machining accuracy of the object to be processed can be improved.

In addition, by selectively irradiating the region corresponding to the inner portion of the peripheral edge of the object to be processed with the energy beam, the second adhesive layer in the region corresponding to the peripheral edge of the object to be processed Since the adhesiveness of (X2) is maintained, the peripheral portion of the object to be processed is prevented from being peeled off from the double-sided adhesive sheet.

Furthermore, in the method for manufacturing a semiconductor device described above, by selectively irradiating the energy beam, the second adhesive layer (X2) has a region corresponding to the peripheral edge of the object to be processed, and an area inside the peripheral edge of the object to be processed. The hardness of the pressure-sensitive adhesive layer in the region corresponding to . However, the object to be processed is fixed to the support by the first pressure-sensitive adhesive layer (X1), and the first pressure-sensitive adhesive layer acts as a kind of buffer layer, so that the hardness in the second pressure-sensitive adhesive layer (X2) is reduced. The difference in thickness can be reduced, the workpiece can be held well, and the backgrinding process can be performed as intended.

As a preliminary step for singulating the object, grooves, which are planned division lines, are formed on the surface of the object to be adhered to the second pressure-sensitive adhesive layer (X2) before the back surface grinding step. and a step of forming a modified region, which is a line to be divided, inside the object before the back surface grinding step.
In the case where the object to be processed has undergone the preparatory step for singulation in advance, the object to be processed is thinned and singulated by performing the back surface grinding step. In this case, the corners and the like of the semiconductor chips generated by singulation are likely to come into contact with the adjacent semiconductor chips, resulting in breakage due to vibration during the back grinding process and energy beam irradiation prior to the back grinding process. The occurrence of problems associated with curing shrinkage of the second pressure-sensitive adhesive layer (X2) tends to become conspicuous. In addition, the back grind tape undergoes the preliminary step for singulation, which tends to cause the back grind tape to deteriorate in handleability.

However, in the method for manufacturing a semiconductor device according to the present embodiment, since the object to be processed is fixed to the support by the first adhesive layer (X1), as described above, the second adhesive layer (X2) These problems are less likely to occur even if a preparatory step for singulation has been performed in advance, because the internal stress of .

The energy beam irradiation process is started before the back surface grinding process. The back surface grinding step may be performed after the energy beam irradiation step is completed, or the back surface grinding step may be started in the middle of the energy beam irradiation step. In the former case, it becomes easier to more reliably suppress the vibration of the workpiece in the back grinding process, and in the latter case, it becomes easier to shorten the time required for the entire manufacturing process.

In the energy beam irradiation step, the energy beam irradiation may be performed by masking a region of the support corresponding to the peripheral edge of the object to be processed.
By masking the region of the support, it becomes easier to prevent energy rays from penetrating into the region of the adhesive layer (X2) corresponding to the region.

A step of separating the first pressure-sensitive adhesive layer (X) from the support (hereinafter also referred to as "first separation step") may be further provided after the back surface grinding step.
The means for separating the first pressure-sensitive adhesive layer (X1) from the support is not particularly limited, but as described later, at least one of the first pressure-sensitive adhesive layer (X1) and the base layer (Y) By forming a thermally expandable layer containing particles, it can be easily separated by heating.

A step of separating the second pressure-sensitive adhesive layer (X2) and the processed workpiece (hereinafter also referred to as a "second separation step") may be further provided after the back surface grinding step.

First, the double-sided pressure-sensitive adhesive sheet used in the method for manufacturing a semiconductor device will be described below. After that, the details of each step included in the semiconductor device manufacturing method will be described based on specific embodiments.

<Double-sided adhesive sheet>
The double-sided pressure-sensitive adhesive sheet (hereinafter also referred to as "double-sided pressure-sensitive adhesive sheet of the present embodiment") used in the method for manufacturing a semiconductor device includes a first pressure-sensitive adhesive layer (X1) as an outer layer on one side and a and a second pressure-sensitive adhesive layer (X2) as an outer layer on the side, and the second pressure-sensitive adhesive layer (X2) has energy ray curability.
In the method for manufacturing a semiconductor device, the support is attached to the first adhesive layer (X1), and the object to be processed is attached to the second adhesive layer (X2). Thus, the object to be processed is fixed to the support by the double-sided pressure-sensitive adhesive sheet. By fixing the workpiece to the support via the double-sided adhesive sheet, when the workpiece is processed, the vibration of the workpiece, the positional deviation of the workpiece, and the fragility of the workpiece can be prevented. Damage and the like can be suppressed, and machining accuracy and machining speed can be improved.
The object to be processed, such as a semiconductor wafer, itself has low energy ray transmittance. Alternatively, even if the material has energy ray transparency, transmission of the energy ray is impeded by circuit wiring, electrodes, etc. provided on the object to be processed. Therefore, in the method for manufacturing a semiconductor device, the specific region of the second pressure-sensitive adhesive layer (X2) is irradiated with energy rays through the support and the first pressure-sensitive adhesive layer (X1). Therefore, at least the support and the first pressure-sensitive adhesive layer (X1) have energy ray transparency.

In the method for manufacturing a semiconductor device, the double-sided pressure-sensitive adhesive sheet further includes a base layer (Y), has a first pressure-sensitive adhesive layer (X1) on one main surface of the base layer, and It may have a second pressure-sensitive adhesive layer (X2) on the other main surface of the layer (Y), or it may have a substrate-less layer that does not have a substrate layer as a core material.
1(a) and 1(b) show schematic cross-sectional views of the double-sided pressure-sensitive adhesive sheet of this embodiment.
The double-sided pressure-sensitive adhesive sheet 1a shown in FIG. 1(a) is a substrate-less double-sided pressure-sensitive adhesive sheet having only the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2).
The double-sided pressure-sensitive adhesive sheet 1b shown in FIG. 1(b) is a double-sided pressure-sensitive adhesive sheet having a first pressure-sensitive adhesive layer (X1), a base layer (Y), and a second pressure-sensitive adhesive layer (X2) in this order. .
The double-sided pressure-sensitive adhesive sheets 1a and 1b described above have a configuration in which a release material is further provided on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) and a release material is further provided on the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2). good too.

When the double-sided pressure-sensitive adhesive sheet is substrateless, as in the double-sided pressure-sensitive adhesive sheet 1a shown in FIG. , the configuration of the double-sided adhesive sheet can be simplified.
When the double-sided pressure-sensitive adhesive sheet has a base material layer (Y) like the double-sided pressure-sensitive adhesive sheet 1b shown in FIG.
When the double-sided pressure-sensitive adhesive sheet has a substrate layer (Y), the substrate layer (Y) also has energy ray transparency.

Any layer other than the second pressure-sensitive adhesive layer (X2) contained in the double-sided pressure-sensitive adhesive sheet may be a thermally expandable layer containing thermally expandable particles. By expanding the heat-expandable particles contained in the heat-expandable layer by heating, the first pressure-sensitive adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet can be easily separated from the support.
In the case where the double-sided pressure-sensitive adhesive sheet includes a thermally expandable layer, for example, in the method for manufacturing a semiconductor device, the support is removed by heating the double-sided pressure-sensitive adhesive sheet after the step of irradiating the energy beam and the step of grinding the back surface. It can be separated from the first adhesive layer (X1).

As the double-sided pressure-sensitive adhesive sheet, the first pressure-sensitive adhesive layer (X1) may be a thermally expandable layer containing thermally expandable particles.
In this case, since the pressure-sensitive adhesive layer contains thermally expandable particles, the expansion of the thermally expandable particles tends to cause unevenness on the surface of the double-sided pressure-sensitive adhesive sheet. In addition, since a substrate layer is not necessarily required, the structure of the double-sided pressure-sensitive adhesive sheet can be easily simplified.
Moreover, when the double-sided pressure-sensitive adhesive sheet includes a substrate layer (Y), the substrate layer (Y) may be a double-sided pressure-sensitive adhesive sheet that is a thermally expandable layer containing thermally expandable particles.
In this case, since the thermally expandable particles do not come into contact with the adherend, contamination of the surface of the adherend due to the thermally expandable particles can be easily suppressed.

The double-sided pressure-sensitive adhesive sheet may have a baseless structure in which the first pressure-sensitive adhesive layer (X1) contains thermally expandable particles, or may have a base layer (Y) and the first pressure-sensitive adhesive layer (X1) may be heat-expandable. A structure containing expandable particles may be used, or a structure containing thermally expandable particles in both the base layer (Y) and the first pressure-sensitive adhesive layer (X1) may be used.

The substrate layer (Y) may be a thermally expandable layer (hereinafter also referred to as “thermally expandable substrate layer (Y1)”), a non-thermally expandable layer (hereinafter, “non-thermally expandable substrate layer (Y2)”).
When the substrate layer (Y) includes the thermally expandable substrate layer (Y1), the deformation of the thermally expandable substrate layer (Y1) due to the expansion of the thermally expandable particles is good for the first pressure-sensitive adhesive layer (X1). From the viewpoint of transmitting to the thermally expandable substrate layer (Y1), it is preferable to include a non-thermally expandable substrate layer (Y2). That is, the double-sided pressure-sensitive adhesive sheet of this embodiment comprises a first pressure-sensitive adhesive layer (X1), a thermally expandable base layer (Y1), a non-thermally expandable base layer (Y2), and a second pressure-sensitive adhesive layer ( X2) in this order.

The double-sided pressure-sensitive adhesive sheet used in the method for manufacturing a semiconductor device preferably comprises a first pressure-sensitive adhesive layer (X1), a thermally expandable base layer (Y1), a non-thermally expandable base layer (Y2), The second pressure-sensitive adhesive layer (X2) has a laminated structure arranged in this order, and the thermally expandable substrate layer (Y1) contains thermally expandable particles in a resin substrate. is.
The resin base material is a base material containing at least a resin, and may contain components other than the resin, such as base material additives, as described later.

The double-sided pressure-sensitive adhesive sheet 1c shown in FIG. Layer (X2) is a double-sided pressure-sensitive adhesive sheet having a laminated structure arranged in this order.
The double-sided pressure-sensitive adhesive sheet 1c may further have a release material on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) and further have a release material on the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2).

Like the double-sided pressure-sensitive adhesive sheet 1c shown in FIG. By heating and expanding the thermally expandable particles contained in the layer (Y1) to a temperature equal to or higher than the expansion start temperature (t), and forming good unevenness on the adhesive surface of the first adhesive layer (X1) , the contact area between the adherend attached to the adhesive surface of the first adhesive layer (X1) and the adhesive surface is greatly reduced. This can significantly reduce the adhesion between the double-sided pressure-sensitive adhesive sheet and the adherend.
Therefore, when the double-sided pressure-sensitive adhesive sheet is peeled off by heating, the double-sided pressure-sensitive adhesive sheet can be peeled off from the adherend simply by applying a small force as a force for peeling off the double-sided pressure-sensitive adhesive sheet. Specifically, as a method for peeling the pressure-sensitive adhesive sheet from the adherend, there are generally methods such as peeling off the pressure-sensitive adhesive sheet, and methods in which there is no support and the single-sided pressure-sensitive adhesive sheet is singulated as the adherend. When the chip is attached, the chip is peeled off from the adhesive sheet by pushing up with a pin from the opposite side of the adhesive sheet to the side to which the chip is attached. However, according to the above double-sided pressure-sensitive adhesive sheet, in a laminate in which the double-sided pressure-sensitive adhesive sheet is attached to an adherend, when the laminate is peeled off by heating, for example, the adherend cannot be separated from the double-sided pressure-sensitive adhesive sheet only by lifting the adherend. can be done.
Furthermore, since the thermally expandable particles are contained in the thermally expandable substrate layer (Y1), contamination of the adherend surface due to the thermally expandable particles is suppressed.

The double-sided pressure-sensitive adhesive sheet has only the first pressure-sensitive adhesive layer (X1), the thermally expandable substrate layer (Y1), the non-thermally expandable substrate layer (Y2), and the second pressure-sensitive adhesive layer (X2). or may have other layers as desired.

In the double-sided pressure-sensitive adhesive sheet, between the first pressure-sensitive adhesive layer (X1) and the thermally expandable substrate layer (Y1), and between the thermally expandable substrate layer (Y1) and the non-thermally expandable substrate layer (Y2) between the non-thermally expandable substrate layer (Y2) and the second pressure-sensitive adhesive layer (X2). It doesn't have to be.
However, in the double-sided pressure-sensitive adhesive sheet, the first pressure-sensitive adhesive layer (X1 ) and the thermally expandable substrate layer (Y1) are preferably directly laminated.

Next, regarding the double-sided pressure-sensitive adhesive sheet, the thermally expandable particles necessary for forming unevenness on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) by heating will be described, and then the first pressure-sensitive adhesive layer (X1) will be described. , the thermally expandable base layer (Y1), the non-thermally expandable base layer (Y2), and the second adhesive layer (X2).

<Thermal expandable particles>
The thermally expandable particles used in the double-sided pressure-sensitive adhesive sheet are not particularly limited as long as they are particles that expand when heated.
One type of the thermally expandable particles may be used alone, or two or more types may be used in combination.

The expansion start temperature (t) of the thermally expandable particles is preferably 50° C. or higher and lower than 125° C., more preferably 55° C. or higher and 120° C. or lower, still more preferably 60° C. or higher and 115° C. or lower, still more preferably 70° C. or higher and 110° C. or higher. °C or less, more preferably 75°C or more and 105°C or less.

When the expansion start temperature (t) of the thermally expandable particles is 50° C. or higher, it tends to be possible to suppress unintended expansion due to frictional heat generated when processing an object to be processed, reaction heat during the energy beam irradiation step, and the like. be. Further, if the expansion start temperature (t) of the thermally expandable particles is less than 125° C., there is a tendency that the thermal change of the object to be processed during thermal separation can be suppressed.
In this specification, the expansion start temperature (t) of thermally expandable particles means a value measured based on the following method.

(Method for measuring expansion start temperature (t) of thermally expandable particles)
An aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm was filled with 0.5 mg of thermally expandable particles to be measured, and an aluminum lid (5.6 mm in diameter and 0.6 mm in thickness) was placed thereon. 1 mm) is placed on the sample.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured while a force of 0.01 N is applied to the sample from the top of the aluminum lid with a pressurizer. Then, while applying a force of 0.01 N by the pressurizer, heat is applied from 20° C. to 300° C. at a temperature increase rate of 10° C./min, and the amount of displacement in the vertical direction of the pressurizer is measured. Let the displacement start temperature be the expansion start temperature (t).

The thermally expandable particles are microencapsulated foaming agents composed of an outer shell made of a thermoplastic resin and an encapsulated component that is encapsulated in the outer shell and vaporizes when heated to a predetermined temperature. Preferably.
Examples of thermoplastic resins constituting the shell of the microencapsulated foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

Examples of encapsulated components that are encapsulated in the outer shell of the microencapsulated foaming agent include propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n- Low boiling point liquids such as heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether are included.
Among these, propane, isobutane, n-pentane, and cyclopropane are preferable as the encapsulated component when the expansion start temperature (t) of the thermally expandable particles is 50° C. or more and less than 125° C.
These inclusion components may be used individually by 1 type, and may use 2 or more types together.
The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of inclusion component.

The average particle size of the thermally expandable particles before expansion at 23° C. is preferably 3 to 100 μm, more preferably 4 to 70 μm, still more preferably 6 to 60 μm, still more preferably 10 to 50 μm.
The average particle size of the thermally expandable particles before expansion is the volume-median particle size (D ₅₀ ), and is measured by a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name "Mastersizer 3000"). In the particle distribution of the thermally expandable particles before expansion measured using , the particle size corresponding to a cumulative volume frequency of 50% calculated from the smallest particle size of the thermally expandable particles before expansion.

The 90% particle diameter (D ₉₀ ) of the thermally expandable particles before expansion at 23° C. is preferably 10 to 150 μm, more preferably 15 to 100 μm, still more preferably 20 to 90 μm, still more preferably 25 to 80 μm. be.
The 90% particle diameter (D ₉₀ ) of the thermally expandable particles before expansion is measured using a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name “Mastersizer 3000”). In the particle distribution of the thermally expandable particles before expansion, it means a particle size corresponding to a cumulative volume frequency of 90% calculated from the smaller particle size of the thermally expandable particles before expansion.

The maximum volume expansion coefficient when heated to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles is preferably 1.5 to 200 times, more preferably 2 to 150 times, and still more preferably 2.5 to 120. times, more preferably 3 to 100 times.

The content of the thermally expandable particles in the thermally expandable layer is preferably from 1 to 40% by mass, more preferably from 5 to 35% by mass, and still more preferably with respect to the total mass (100% by mass) of the thermally expandable layer. is 10 to 30% by weight, more preferably 15 to 25% by weight.

<Total light transmittance>
In the second separation step, which will be described later, the pressure-sensitive adhesive layer (X2) may be irradiated with energy rays through the thermally expandable layer after the thermally expandable particles have expanded. At this time, from the viewpoint of efficiently irradiating the pressure-sensitive adhesive layer (X2) with energy rays even through the thermally expandable layer, the pressure-sensitive adhesive layer (X2) of the double-sided pressure-sensitive adhesive sheet of one embodiment of the present invention has For measuring total light transmittance, a laminate obtained by laminating glass plates made of soda-lime glass and having a thickness of 1.1 mm is heated at a temperature of expansion start temperature (t) of thermally expandable particles + 22°C for 1 minute. The laminate preferably has a total light transmittance of 20% or more at a wavelength of 380 nm in the thickness direction.

<First adhesive layer (X1)>
The first pressure-sensitive adhesive layer (X1) is a pressure-sensitive adhesive layer as an outer layer on one side of the double-sided pressure-sensitive adhesive sheet of the present embodiment. The first pressure-sensitive adhesive layer (X1) preferably has energy ray transparency.
The first pressure-sensitive adhesive layer (X1), when the double-sided pressure-sensitive adhesive sheet includes a heat-expandable layer, is a layer on the surface of which irregularities are formed due to heat-expandable particles expanded by heating. The first pressure-sensitive adhesive layer (X1) has a reduced contact area with the adherend and can be easily peeled off from the adherend.
The first adhesive layer (X1) can be formed, for example, from an adhesive composition (x-1) containing an adhesive resin.

(Adhesive composition (x-1))
The adhesive composition (x-1) contains an adhesive resin.

(adhesive resin)
Examples of the adhesive resin include a polymer having adhesiveness by itself and having a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and still more preferably 30,000, from the viewpoint of improving the adhesive strength of the first adhesive layer (X1). ~1 million.

Specific examples of adhesive resins include acrylic resins, urethane resins, rubber resins such as polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins.
These adhesive resins may be used alone or in combination of two or more.
In addition, when these adhesive resins are copolymers having two or more structural units, the form of the copolymer is not particularly limited, and may be block copolymers, random copolymers, and graft copolymers. Any polymer may be used.

Examples of adhesive resins include acrylic resins, urethane resins, polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. Among these, the adhesive resin preferably contains an acrylic resin from the viewpoint of expressing excellent adhesive strength in the first adhesive layer (X1) and imparting good energy ray transmittance.

The content of the acrylic resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 30 to 100% by mass, based on the total amount (100% by mass) of the adhesive resin contained in the adhesive composition (x-1). is 50 to 100% by mass, more preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1,500,000, more preferably 200,000 to 1,300,000, still more preferably 350,000 to 1,200,000, and even more preferably 500,000 to 1,100,000.

Examples of acrylic resins include polymers containing structural units derived from alkyl (meth)acrylates having alkyl groups, polymers containing structural units derived from (meth)acrylates having a cyclic structure, and the like. . Among these, a polymer containing a structural unit derived from an alkyl (meth)acrylate having an alkyl group is preferable, and is derived from an alkyl (meth)acrylate (a1′) (hereinafter also referred to as “monomer (a1′)”). and a functional group-containing monomer (a2′) (hereinafter also referred to as “monomer (a2′)”).

The number of carbon atoms in the alkyl group of the monomer (a1') is preferably 1 to 24, more preferably 1 to 12, and still more preferably 2-10, more preferably 4-8.
In this specification, unless otherwise specified, the "alkyl group" may be linear or branched.

Examples of the monomer (a1′) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, iso-butyl (meth)acrylate, Acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate and the like. Among these, n-butyl acrylate and 2-ethylhexyl acrylate are preferred.
Monomer (a1′) may be used alone or in combination of two or more.

The content of the structural unit (a1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, based on the total structural units (100% by mass) of the acrylic copolymer (A1). %, more preferably 70 to 97.0% by mass, and even more preferably 80 to 95.0% by mass.

Examples of functional groups possessed by the monomer (a2′) include hydroxyl groups, carboxyl groups, amino groups, epoxy groups and the like.
That is, examples of the monomer (a2′) include hydroxyl group-containing monomers, carboxy group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and the like.
These monomers (a2') may be used alone or in combination of two or more.
Among these, the monomer (a2') is preferably a hydroxyl group-containing monomer or a carboxy group-containing monomer, more preferably a hydroxyl group-containing monomer.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, ) hydroxyalkyl (meth)acrylates such as acrylate and 4-hydroxybutyl (meth)acrylate; and hydroxyl group-containing compounds such as unsaturated alcohols such as vinyl alcohol and allyl alcohol.

Carboxy group-containing monomers include, for example, ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and their anhydrides ; 2-(acryloyloxy)ethyl succinate, 2-carboxyethyl (meth)acrylate and the like.

The content of the structural unit (a2) is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, based on the total structural units (100% by mass) of the acrylic copolymer (A1). %, more preferably 1.0 to 15% by mass, and even more preferably 3.0 to 10% by mass.

The acrylic copolymer (A1) may further have a structural unit (a3) derived from a monomer (a3') other than the monomers (a1') and (a2').
In the acrylic copolymer (A1), the total content of the structural units (a1) and (a2) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass.

The content of the adhesive resin in the adhesive composition (x-1) is preferably 35 to 100% by mass with respect to the total amount (100% by mass) of the active ingredients in the adhesive composition (x-1), More preferably 50 to 100% by mass, still more preferably 60 to 100% by mass, still more preferably 70 to 99.5% by mass.

(crosslinking agent)
When the pressure-sensitive adhesive composition (x-1) contains a pressure-sensitive adhesive resin having a functional group, it preferably further contains a cross-linking agent.
The cross-linking agent reacts with the adhesive resin having a functional group to cross-link the adhesive resins with the functional group as a cross-linking starting point.

Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.
One of these crosslinking agents may be used alone, or two or more thereof may be used in combination.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoints of increasing cohesive strength and improving adhesive strength, and from the viewpoints of availability and the like.
Examples of isocyanate-based cross-linking agents include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate; Alicyclic polyisocyanates such as methylcyclohexylene diisocyanate, methylenebis(cyclohexyl isocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, hydrogenated xylylene diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate acyclic aliphatic polyisocyanates such as; polyvalent isocyanate compounds such as;
Examples of the isocyanate-based cross-linking agent include trimethylolpropane adduct-type modified products of the polyvalent isocyanate compounds, biuret-type modified products reacted with water, and isocyanurate-type modified products containing an isocyanurate ring.
Among these, from the viewpoint of suppressing the deterioration of the elastic modulus of the first pressure-sensitive adhesive layer (X1) during heating and suppressing the adhesion of residues derived from the first pressure-sensitive adhesive layer (X1) to the adherend, It is preferable to use an isocyanurate-type modified product containing an isocyanurate ring, it is more preferable to use an isocyanurate-type modified product of an acyclic aliphatic polyisocyanate, and it is further preferable to use an isocyanurate-type modified product of hexamethylene diisocyanate. preferable.

The content of the cross-linking agent is appropriately adjusted according to the number of functional groups possessed by the adhesive resin. More preferably 0.03 to 7 parts by mass, still more preferably 0.05 to 5 parts by mass.

(Tackifier)
The pressure-sensitive adhesive composition (x-1) may further contain a tackifier from the viewpoint of further improving the adhesive strength.
As used herein, the term "tackifier" refers to a component that supplementarily improves the adhesive strength of the adhesive resin and has a weight-average molecular weight (Mw) of less than 10,000.
The weight average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, still more preferably 800 to 5,000.

Examples of tackifiers include rosin-based resins, terpene-based resins, styrene-based resins, pentene produced by thermal decomposition of petroleum naphtha, isoprene, piperine, obtained by copolymerizing C5 fractions such as 1,3-pentadiene. and C9 petroleum resins obtained by copolymerizing C9 fractions such as indene and vinyl toluene produced by thermal decomposition of petroleum naphtha, and hydrogenated resins obtained by hydrogenating these.

The content of the tackifier is preferably 0.01 to 65% by mass, more preferably 0.1 to 50% by mass, relative to the total amount (100% by mass) of the active ingredients of the adhesive composition (x-1). %, more preferably 1 to 40% by mass, and even more preferably 2 to 30% by mass.

(Adhesive additive)
The pressure-sensitive adhesive composition (x-1) may contain additives for pressure-sensitive adhesives used in general pressure-sensitive adhesives, in addition to the additives described above, within a range that does not impair the effects of the present invention. .
Examples of adhesive additives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), and UV absorbers.
In addition, these additives for pressure-sensitive adhesives may be used alone, respectively, or two or more of them may be used in combination.

When the pressure-sensitive adhesive composition (x-1) contains a pressure-sensitive adhesive additive, the content of each pressure-sensitive adhesive additive is independently preferably 0 per 100 parts by mass of the pressure-sensitive adhesive resin. 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass.

(Polymerizable composition)
When the first pressure-sensitive adhesive layer (X1) is a thermally expandable layer, the first pressure-sensitive adhesive layer (X1) may be formed from the above-described pressure-sensitive adhesive composition (x-1), but after application From the viewpoint of suppressing the expansion of the thermally expandable particles during the drying process, it is preferable to form by irradiating the polymerizable composition containing the energy ray-polymerizable component and the thermally expandable particles with an energy ray. By using a polymerizable composition to form the first pressure-sensitive adhesive layer (X1), there is no need to use a solvent and the drying step can be omitted, so the thermal expansion with a relatively low expansion start temperature (t) can be selected.
As the energy ray-polymerizable component, for example, various monomers exemplified as raw material monomers for the acrylic resin described above as the adhesive resin can be used.
The polymerizable composition preferably contains a photopolymerization initiator from the viewpoint of sufficiently advancing the energy ray polymerization reaction. As the photopolymerization initiator, the photopolymerization initiator described in the solventless resin composition (y-1a) described later can be used. In addition, the polymerizable composition may contain the crosslinking agent, tackifier, adhesive additive, etc. described in the above adhesive composition (x-1).

(Adhesive strength of the first adhesive layer (X1) before thermally expanding the thermally expandable layer)
The adhesive strength of the first adhesive layer (X1) before thermally expanding the thermally expandable layer is preferably 0.1 to 12.0 N/25 mm, more preferably 0.5 to 9.0 N/25 mm, and even more preferably is 1.0 to 8.0 N/25 mm, more preferably 1.2 to 7.5 N/25 mm.
When the adhesive strength of the first pressure-sensitive adhesive layer (X1) before thermally expanding the thermally expandable layer is 0.1 N/25 mm or more, unintended peeling from the support during temporary fixing, misalignment, etc. are more effectively prevented. tend to be effectively suppressed. Further, when the adhesive strength is 12.0 N/25 mm or less, the peelability at the time of heat peeling can be further improved.

(Adhesive strength of the first adhesive layer (X1) after thermally expanding the thermally expandable layer)
The adhesive strength of the first pressure-sensitive adhesive layer (X1) after thermally expanding the thermally expandable layer is preferably 1.5 N/25 mm or less, more preferably 0.05 N/25 mm or less, still more preferably 0.01 N/25 mm or less. 25 mm or less, more preferably 0 N/25 mm. The adhesive force of 0 N/25 mm means an adhesive force below the measurable limit in the method for measuring adhesive force described above. A case of unintentional peeling is also included.

(Thickness of first adhesive layer (X1))
The thickness of the first pressure-sensitive adhesive layer (X1) expresses good adhesive strength, and the layers other than the pressure-sensitive adhesive layer (X2) such as the base layer (Y) and the pressure-sensitive adhesive layer (X1) are thermally expandable. In the case of a layer, from the viewpoint of favorably forming irregularities on the adhesive surface of the first adhesive layer (X1) when the thermally expandable particles in the thermally expandable layer are expanded by heating, preferably 3 ~10 μm, more preferably 3-8 μm, still more preferably 3-7 μm.
The thickness of the first pressure-sensitive adhesive layer (X1) is measured using a constant-pressure thickness measuring instrument manufactured by Teclock Co., Ltd. (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709). is the value The same applies to the thickness of each layer to be described later.

<Base material layer (Y)>
The substrate layer (Y) preferably has energy ray transparency, and is preferably a layer made of a non-adhesive substrate.
The probe tack value on the surface of the substrate layer (Y) is usually less than 50 mN/5 mmφ, preferably less than 30 mN/5 mmφ, more preferably less than 10 mN/5 mmφ, still more preferably less than 5 mN/5 mmφ.
In addition, in this specification, the probe tack value on the surface of the substrate means the value measured by the following method.
(Method for measuring probe tack value)
After cutting the base material to be measured into a square with a side of 10 mm, a test sample was left to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours. ), using a tacking tester (manufactured by Nippon Tokushu Sokki Co., Ltd., product name “NTS-4800”), the probe tack value on the surface of the test sample is measured in accordance with JIS Z0237: 1991. be able to. Specifically, a stainless steel probe with a diameter of 5 mm was brought into contact with the surface of the test sample at a contact load of 0.98 N/cm ² for 1 second, and then the probe was moved at a speed of 10 mm/second to the surface of the test sample. The force required to remove it from the surface can be measured and the resulting value taken as the probe tack value for that test sample.

The substrate layer (Y) may be subjected to, for example, a surface treatment such as an oxidation method or a roughening method, an adhesion-facilitating treatment, or a primer treatment, from the viewpoint of improving interlayer adhesion with other layers.
Examples of oxidation methods include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, and ultraviolet irradiation treatment. Examples of roughening methods include sandblasting, solvent treatment, and the like. are mentioned.

As described above, the base layer (Y) may be the thermally expandable base layer (Y1) or the non-thermally expandable base layer (Y2).
When the substrate layer (Y) includes the thermally expandable substrate layer (Y1), the deformation of the thermally expandable substrate layer (Y1) due to the expansion of the thermally expandable particles is good for the first pressure-sensitive adhesive layer (X1). From the viewpoint of transmitting to the thermally expandable substrate layer (Y1), it is preferable to include a non-thermally expandable substrate layer (Y2). That is, the double-sided pressure-sensitive adhesive sheet of this embodiment includes a first pressure-sensitive adhesive layer (X1), a thermally expandable base layer (Y1), and a non- It is preferable to have the thermally expandable substrate layer (Y2) and the second adhesive layer (X2) in this order.

<Thermal expandable base layer (Y1)>
The thermally expandable substrate layer (Y1) can be formed, for example, from a resin composition (y-1) containing a resin and thermally expandable particles.

(Resin composition (y-1))
Resin composition (y-1) is a resin composition containing a resin and thermally expandable particles.

(resin)
The resin contained in the resin composition (y-1) may be a non-adhesive resin or a tacky resin. Even if the resin contained in the resin composition (y-1) is an adhesive resin, in the process of forming the thermally expandable base layer (Y1) from the resin composition (y-1), the adhesive resin is It is sufficient that the polymerizable compound undergoes a polymerization reaction, the resulting resin becomes a non-adhesive resin, and the thermally expandable substrate layer (Y1) becomes non-adhesive.
One of the above resins may be used alone, or two or more thereof may be used in combination.

The mass average molecular weight (Mw) of the resin is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and still more preferably 1,000 to 500,000.

The resin may be a polymer having a single structural unit, or a copolymer having two or more structural units. When the resin is a copolymer, the form of the copolymer may be block copolymer, random copolymer or graft copolymer.

The above resin contained in the resin composition (y-1) has a viewpoint of facilitating the formation of irregularities on the adhesive surface of the first adhesive layer (X1) and improving the sheet shape retention after thermal expansion. From the viewpoint of imparting good energy ray transparency, it is preferable to contain one or more selected from the group consisting of acrylic urethane-based resins and olefin-based resins.

(acrylic urethane resin)
As the acrylic urethane resin, the following resin (U1) is preferable.
• An acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth)acrylic acid ester.
In the present specification, the term "prepolymer" means a compound obtained by polymerizing a monomer and capable of forming a polymer by further polymerization.

Urethane prepolymers (UP) include reaction products of polyols and polyvalent isocyanates.
In addition, it is preferable that the urethane prepolymer (UP) is obtained by subjecting the urethane prepolymer (UP) to a chain extension reaction using a chain extension agent.

Examples of polyols used as raw materials for urethane prepolymers (UP) include alkylene-type polyols, ether-type polyols, ester-type polyols, esteramide-type polyols, ester/ether-type polyols, and carbonate-type polyols.
These polyols may be used alone or in combination of two or more.
The polyol used in one aspect of the present invention is preferably a diol, more preferably an ester-type diol, an alkylene-type diol or a carbonate-type diol, and still more preferably an ester-type diol or a carbonate-type diol.

Examples of ester diols include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol and 1,6-hexanediol; ethylene glycol, propylene glycol, 1 or 2 or more selected from diols such as alkylene glycols such as diethylene glycol and dipropylene glycol; ,4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, het acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa Condensation products of one or more selected from dicarboxylic acids such as hydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, methylhexahydrophthalic acid, and anhydrides thereof may be mentioned.
Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, Polydiethylene adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, polyneo pentyl terephthalate diol and the like.

Aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and the like are examples of polyvalent isocyanates that are raw materials for urethane prepolymers (UP).
One of these polyvalent isocyanates may be used alone, or two or more thereof may be used in combination.
Further, these polyvalent isocyanates may be trimethylolpropane adduct-type modified products, biuret-type modified products reacted with water, and isocyanurate-type modified products containing an isocyanurate ring.

Among these, diisocyanates are preferred as polyvalent isocyanates, and 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2, 6-TDI), hexamethylene diisocyanate (HMDI), and one or more selected from alicyclic diisocyanates are more preferred.

Alicyclic diisocyanates include, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane Examples include diisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, and isophorone diisocyanate (IPDI) is preferred.

As the urethane prepolymer (UP), a linear urethane prepolymer having ethylenically unsaturated groups at both ends is preferred.
Examples of ethylenically unsaturated groups include (meth)acryloyl groups, vinyl groups, and allyl groups, and among these, (meth)acryloyl groups are preferred.
As a method for introducing ethylenically unsaturated groups at both ends of the linear urethane prepolymer, an NCO group at the terminal of the linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound, and a hydroxyalkyl (meth)acrylate and a method of reacting with.
Examples of the hydroxyalkyl (meth)acrylate to be reacted with the terminal NCO group include the same hydroxyalkyl (meth)acrylates as the monomer (a2′) described above.

(Olefin resin)
The olefin-based resin suitable as the resin contained in the resin composition (y-1) is a polymer having at least structural units derived from an olefin monomer.
As the olefin monomer, α-olefins having 2 to 8 carbon atoms are preferable, and specific examples include ethylene, propylene, butylene, isobutylene, 1-hexene, and the like.
Among these, ethylene and propylene are preferred.

The olefin-based resin may be a modified olefin-based resin further subjected to one or more modifications selected from acid-modified, hydroxyl-modified and acrylic-modified.

For example, the acid-modified olefin resin obtained by subjecting an olefin resin to acid modification is a modified polymer obtained by graft-polymerizing an unsaturated carboxylic acid or its anhydride to the above-described unmodified olefin resin. are mentioned.
Examples of unsaturated carboxylic acids or anhydrides thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth)acrylic acid, maleic anhydride, and itaconic anhydride. , glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride and the like.
In addition, unsaturated carboxylic acid or its anhydride may be used individually by 1 type, and may use 2 or more types together.

The acrylic-modified olefin-based resin obtained by subjecting an olefin-based resin to acrylic modification includes modification obtained by graft-polymerizing an alkyl (meth)acrylate as a side chain to the above-described unmodified olefin-based resin that is the main chain. polymers.
The number of carbon atoms in the alkyl group of the above alkyl (meth)acrylate is preferably 1-20, more preferably 1-16, still more preferably 1-12.
Examples of the above alkyl (meth)acrylates include the same compounds as the above-described compounds that can be selected as the monomer (a1′).

Examples of the hydroxyl group-modified olefin resin obtained by modifying the olefin resin with hydroxyl groups include a modified polymer obtained by graft polymerizing a hydroxyl group-containing compound to the above-described unmodified olefin resin that is the main chain.
Examples of the hydroxyl group-containing compound include those similar to the hydroxyl group-containing compounds exemplified as the monomer (a2′) described above.

(Resins other than acrylic urethane resins and olefin resins)
In one aspect of the present invention, the resin composition (y-1) may contain a resin other than the acrylic urethane-based resin and the olefin-based resin within a range that does not impair the effects of the present invention.
Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; Coalescence; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resins; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; Fluorinated resins and the like are included.

However, from the viewpoint of making it easier to form unevenness on the adhesive surface of the first pressure-sensitive adhesive layer (X1) and from the viewpoint of improving the sheet shape retention after thermal expansion, the acrylic urethane in the resin composition (y-1) It is preferable that the content of the resin other than the base resin and the olefin resin is as small as possible.
The content of the resin other than the acrylic urethane resin and the olefin resin is preferably less than 30 parts by mass, more preferably 20 parts by mass, with respect to 100 parts by mass of the total resin contained in the resin composition (y-1). Less than 10 parts by weight, more preferably less than 5 parts by weight, and even more preferably less than 1 part by weight.

(Additive for base material)
The resin composition (y-1) may contain additives for base materials, if necessary, to the extent that the effects of the present invention are not impaired.
Examples of base material additives include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, colorants, and the like.
The base material additives may be used alone, or two or more of them may be used in combination.
When the resin composition (y-1) contains a base material additive, the content of each base material additive is preferably 0.0001 to 0.0001 to 100 parts by mass of the resin independently. 20 parts by mass, more preferably 0.001 to 10 parts by mass.

The resin composition (y-1) may be diluted with a solvent. Examples of solvents include organic solvents such as alcohols such as toluene, ethyl acetate, methyl ethyl ketone, acetone, and isopropyl alcohol. However, as in the case where the pressure-sensitive adhesive layer (X1) contains thermally expandable particles, from the viewpoint of suppressing the expansion of the thermally expandable particles during the drying process after coating, the energy ray-polymerizable component and the thermally expandable It is preferable to form the thermally expandable substrate layer (Y1) by irradiating the solvent-free resin composition (y-1a) containing particles and containing no solvent with energy rays.

(Solvent-free resin composition (y-1a))
As one embodiment of the solvent-free resin composition (y-1a), an oligomer having an ethylenically unsaturated group with a mass average molecular weight (Mw) of 50,000 or less as an energy ray-polymerizable component (hereinafter simply referred to as "ethylenic (also referred to as "an unsaturated group-containing oligomer") and an energy ray-polymerizable monomer, and the above-mentioned thermally expandable particles, and a resin composition containing no solvent.
Although the solvent-free resin composition (y-1a) does not contain a solvent, the energy ray-polymerizable monomer contributes to improving the plasticity of the oligomer.
By irradiating the solvent-free resin composition (y-1a) with an energy ray, an oligomer having an ethylenically unsaturated group, an energy ray-polymerizable monomer, etc. are polymerized to form a thermally expandable base layer (Y1 ) is formed.
Examples of the ethylenically unsaturated group include those mentioned above, and among these, a (meth)acryloyl group is preferred.

The weight average molecular weight (Mw) of the oligomer contained in the solventless resin composition (y-1a) is 50,000 or less, preferably 1,000 to 50,000, more preferably 2,000 to 40,000, more preferably 3,000 to 35,000, even more preferably 4,000 to 30,000.

Further, as the oligomer, among the resins contained in the resin composition (y-1) described above, those having an ethylenically unsaturated group having a mass average molecular weight of 50,000 or less may be used. A prepolymer (UP) is preferred, and a linear urethane prepolymer having ethylenically unsaturated groups at both ends is more preferred.
A modified olefinic resin having an ethylenically unsaturated group can also be used as the oligomer.

The total content of the oligomer and the energy ray-polymerizable monomer in the solvent-free resin composition (y-1a) is based on the total amount (100 mass%) of the solvent-free resin composition (y-1a) It is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, even more preferably 65 to 90% by mass, still more preferably 70 to 85% by mass.

As the energy ray-polymerizable monomer, an energy ray-polymerizable monofunctional monomer having only one energy ray-polymerizable functional group may be used, or an energy ray-polymerizable polyfunctional monomer having two or more energy ray-polymerizable functional groups may be used. A monomer may be used, but from the viewpoint of obtaining a flexible thermally expandable substrate layer (Y1) that does not hinder the expansion of the thermally expandable particles, it is preferable to use at least an energy ray-polymerizable monofunctional monomer. Energy ray-polymerizable monofunctional monomers include, for example, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, alicyclic polymerizable compounds such as adamantane (meth)acrylate and tricyclodecane acrylate; aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate, and phenol ethylene oxide-modified acrylate; Examples include heterocyclic polymerizable compounds such as N-vinylpyrrolidone and N-vinylcaprolactam.
One of these energy ray-polymerizable monomers may be used alone, or two or more thereof may be used in combination. may

The content ratio [oligomer/energy ray-polymerizable monomer] of the oligomer to the energy ray-polymerizable monomer in the solvent-free resin composition (y-1a) is preferably 20/80 to 90/10, more preferably 30/70 to 85/15, still more preferably 35/65 to 80/20.

The solvent-free resin composition (y-1a) preferably further contains a photopolymerization initiator.
By containing a photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.

Examples of photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram. monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and the like. Among these, 1-hydroxycyclohexylphenyl ketone is preferred.
One of these photopolymerization initiators may be used alone, or two or more thereof may be used in combination.
The amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and further preferably 0.01 to 5 parts by mass, based on the total amount (100 parts by mass) of the oligomer and the energy ray-polymerizable monomer. It is preferably 0.02 to 3 parts by mass.

(Thickness of thermally expandable base layer (Y1))
The thickness of the thermally expandable substrate layer (Y1) before thermal expansion is preferably 10 to 200 μm, more preferably 20 to 150 μm, still more preferably 25 to 120 μm.
When the thickness of the thermally expandable base layer (Y1) before thermal expansion is 10 μm or more, unevenness caused by the thermally expandable particles before thermal expansion is less likely to appear on the surface of the first pressure-sensitive adhesive layer (X1). tend to become Moreover, when the thickness of the thermally expandable substrate layer (Y1) before thermal expansion is 200 μm or less, the double-sided pressure-sensitive adhesive sheet tends to be excellent in handleability.

<Non-thermally expandable base layer (Y2)>
Examples of materials for forming the non-thermally expandable base material layer (Y2) include resins, metals, and paper materials.

Examples of the resin used for the non-thermally expandable base layer (Y2) include polyolefin resins such as polyethylene and polypropylene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol. Vinyl resins such as copolymers; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins;
Examples of metals include aluminum, tin, chromium, and titanium.
Examples of the paper material include thin paper, medium quality paper, fine paper, impregnated paper, coated paper, art paper, parchment paper, and glassine paper.
Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred.

These forming materials may be composed of one type, or two or more types may be used in combination.
The non-thermally expandable base material layer (Y2) using two or more forming materials in combination includes a paper material laminated with a thermoplastic resin such as polyethylene, a resin film or sheet containing a resin, and a metal film formed on the surface of the sheet. and the like.
As a method for forming the metal layer, for example, a method of depositing the above metal by a PVD method such as vacuum deposition, sputtering, or ion plating, or a method of attaching a metal foil made of the above metal using a general adhesive. and the like.

When the non-thermally expandable base material layer (Y2) contains a resin, it may contain the above base material additives that may be contained in the resin composition (y-1) together with the resin.

(Storage elastic modulus E′ (23) at 23° C. of the non-thermally expandable base layer (Y2))
The storage modulus E'(23) of the non-thermally expandable substrate layer (Y2) at 23° C. is preferably 5.0×10 ⁷ to 5.0×10 ⁹ Pa, more preferably 5.0×10 ⁸ to 4.5×10 ⁹ Pa, more preferably 1.0×10 ⁹ to 4.0×10 ⁹ Pa.
When the storage elastic modulus E′(23) of the non-thermally expandable base layer (Y2) is 5.0×10 ⁷ Pa or more, the deformation resistance of the double-sided PSA sheet can be easily improved. On the other hand, if the storage elastic modulus E′(23) of the non-thermally expandable base layer (Y2) is 5.0×10 ⁹ Pa or less, the handleability of the double-sided PSA sheet can be easily improved.
In addition, in this specification, the storage elastic modulus E'(23) of the non-thermally expandable base layer (Y2) can be measured by the following method.

(Storage modulus E' (23))
Using a non-thermally expandable base material layer (Y2) cut to 30 mm long and 5 mm wide as a test sample, using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "DMAQ800"), the test start temperature The storage elastic modulus E' at 23°C is the value measured under the conditions of 0°C, a test end temperature of 200°C, a heating rate of 3°C/min, a frequency of 1 Hz, and an amplitude of 20 µm.

(Thickness of non-thermally expandable base layer (Y2))
The thickness of the non-thermally expandable base layer (Y2) is preferably 5-500 μm, more preferably 15-300 μm, and still more preferably 20-200 μm. If the thickness of the non-thermally expandable base layer (Y2) is 5 μm or more, the deformation resistance of the double-sided PSA sheet can be easily improved. On the other hand, if the thickness of the non-thermally expandable base material layer (Y2) is 500 µm or less, it is easy to improve the handleability of the double-sided pressure-sensitive adhesive sheet.

<Second adhesive layer (X2)>
The second pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer as an outer layer on the other side of the double-sided pressure-sensitive adhesive sheet of the present embodiment, and is an energy ray-curable pressure-sensitive adhesive having the property of being cured by irradiation with energy rays. layer.
The second pressure-sensitive adhesive layer (X2) can be formed, for example, from a pressure-sensitive adhesive composition (x-2) containing an energy ray-polymerizable component.

(Adhesive composition (x-2))
The adhesive composition (x-2) contains an energy ray-polymerizable component.
The pressure-sensitive adhesive composition (x-2) may contain, as the energy-ray-polymerizable component, an adhesive resin having an energy-ray-polymerizable functional group (hereinafter also referred to as "energy-ray-polymerizable adhesive resin"). preferable.

(Energy ray polymerizable adhesive resin)
Examples of the energy ray-polymerizable functional group possessed by the energy ray-polymerizable adhesive resin include the same groups as those described above. Among these, a (meth)acryloyl group is preferred.
The energy ray-polymerizable adhesive resin may be used alone or in combination of two or more.

The energy ray-polymerizable adhesive resin may have a single structural unit, or may be a copolymer having two or more structural units. When the energy ray-polymerizable adhesive resin is a copolymer, the form of the copolymer may be any of block copolymer, random copolymer and graft copolymer.

Examples of the energy ray-polymerizable adhesive resin include acrylic resins, urethane-based resins, rubber-based resins, silicone-based resins, and the like, which have energy ray-polymerizable properties. Among these, acrylic resins having energy ray polymerizability are preferred, and acrylic copolymers having energy ray polymerizability (hereinafter also referred to as “acrylic copolymer (A2)”) are more preferred.

From the viewpoint of further improving the adhesive strength of the second pressure-sensitive adhesive layer (X2), the acrylic copolymer (A2) contains a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms. It is preferable to contain.
Structural units derived from alkyl (meth)acrylates having an alkyl group with 4 or more carbon atoms may be used singly or in combination of two or more.
The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate having 4 or more carbon atoms in the alkyl group is preferably 4 to 12, more preferably 4 to 8, and still more preferably 4 to 6.
Examples of alkyl (meth)acrylates in which the alkyl group has 4 or more carbon atoms include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, and nonyl (meth)acrylate. Acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate and the like. Among these, 2-ethylhexyl (meth)acrylate is preferred, and 2-ethylhexyl acrylate is more preferred.
From the viewpoint of adhesiveness, the content of the alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, still more preferably 40 to 60% by mass.

The acrylic copolymer (A2) is derived from an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms from the viewpoint of improving the elastic modulus and adhesive properties of the second pressure-sensitive adhesive layer (X2). It is preferable to contain a structural unit derived from an alkyl (meth)acrylate in which the alkyl group has 1 to 3 carbon atoms together with the structural unit.
Structural units derived from alkyl (meth)acrylates in which the alkyl group has 1 to 3 carbon atoms may be used singly or in combination of two or more.
Examples of alkyl (meth)acrylates having 1 to 3 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate and the like. . Among these, methyl (meth)acrylate and ethyl (meth)acrylate are preferred, and methyl methacrylate and ethyl acrylate are more preferred.
The content of structural units derived from alkyl (meth)acrylates in which the alkyl group has 1 to 3 carbon atoms is preferably 1 in all structural units derived from acrylic monomers constituting the acrylic copolymer (A2). to 35% by mass, more preferably 5 to 30% by mass, and even more preferably 15 to 25% by mass.

The acrylic copolymer (A2) preferably further contains structural units derived from functional group-containing monomers.
By containing a structural unit derived from a functional group-containing monomer, the acrylic copolymer (A2) reacts with a functional group as a cross-linking starting point that reacts with a cross-linking agent, or with an ethylenically unsaturated group-containing compound to form an acrylic A functional group can be introduced that enables introduction of an ethylenically unsaturated group into the side chain of the system copolymer (A2).
The structural units derived from the functional group-containing monomers contained in the acrylic copolymer (A2) may be one type alone or two or more types.

Examples of functional group-containing monomers include the same hydroxyl group-containing monomers and carboxy group-containing monomers as the monomer (a2') described above. Among these, hydroxyl group-containing monomers are preferred, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl acrylate is even more preferred.

The content of the structural unit derived from the functional group-containing monomer is preferably 1 to 40% by mass, more preferably 10 to 35% by mass, in all the structural units derived from the acrylic monomer constituting the acrylic copolymer (A2). %, more preferably 20 to 30 mass %.

The acrylic copolymer (A2) may contain, in addition to the above structural units, structural units derived from other monomers copolymerizable with acrylic monomers.
The structural units derived from other monomers contained in the acrylic copolymer (A2) may be of one type alone or two or more types.

The acrylic copolymer (A2) is preferably one into which an ethylenically unsaturated group is introduced in order to impart energy ray curability.
The ethylenically unsaturated group is, for example, a functional group of the acrylic copolymer (A2) containing a structural unit derived from a functional group-containing monomer, a reactive substituent having reactivity with the functional group, and an ethylenically unsaturated group. It can be introduced by reacting with a reactive substituent of a compound having a saturated group (hereinafter also referred to as "unsaturated group-containing compound"). The unsaturated group-containing compounds may be used singly or in combination of two or more.

Examples of the ethylenically unsaturated group possessed by the unsaturated group-containing compound include those mentioned above, and among these, a (meth)acryloyl group is preferred.
Examples of reactive substituents that the unsaturated group-containing compound has include an isocyanate group and a glycidyl group.
Examples of unsaturated group-containing compounds include 2-(meth)acryloyloxyethyl isocyanate, (meth)acryloylisocyanate, glycidyl (meth)acrylate and the like. Among these, 2-(meth)acryloyloxyethyl isocyanate is preferred, and 2-methacryloyloxyethyl isocyanate is more preferred.

When the acrylic copolymer (A2) containing structural units derived from functional group-containing monomers is reacted with the unsaturated group-containing compound, the total number of functional groups in the acrylic copolymer (A2) is The ratio of functional groups that react with the unsaturated group-containing compound is preferably 30 to 96 mol%, more preferably 60 to 94 mol%, still more preferably 80 to 92 mol%.
When the ratio of the functional group that reacts with the unsaturated group-containing compound is within the above range, it is possible to impart sufficient energy ray curability to the acrylic copolymer (A2), and it does not react with the unsaturated group-containing compound. The functional groups can be reacted with a cross-linking agent to cross-link the acrylic copolymer (A2).

The mass average molecular weight (Mw) of the acrylic copolymer (A2) is preferably 200,000 to 1,500,000, more preferably 300,000 to 1,000,000, still more preferably 400,000 to 600,000.
When the mass average molecular weight (Mw) of the acrylic copolymer (A2) is within the above range, the adhesive strength and cohesive strength tend to be better.

(Energy ray-curable compound)
The pressure-sensitive adhesive composition (x-2) may further contain an energy ray-curable compound other than the above components for the purpose of adjusting the cohesion of the second pressure-sensitive adhesive layer (X2).
The energy ray-curable compounds may be used singly or in combination of two or more.
Energy ray-curable compounds include, for example, monomers or oligomers that can be polymerized and cured by energy ray irradiation.
Examples of energy ray-curable compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butylene glycol. Polyvalent (meth)acrylate monomers such as di(meth)acrylate and 1,6-hexanediol (meth)acrylate; urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate oligomers such as acrylate; Among these, urethane (meth)acrylate is preferred. Urethane (meth)acrylate is preferably polyfunctional urethane (meth)acrylate.
When the pressure-sensitive adhesive composition (x-2) contains an energy ray-curable compound, the content of the energy ray-curable compound is preferably 1 to 30 mass parts with respect to 100 parts by mass of the energy ray-polymerizable adhesive resin. parts, more preferably 5 to 20 parts by mass, still more preferably 8 to 15 parts by mass.

(Photoinitiator)
The adhesive composition (x-2) preferably contains a photopolymerization initiator. By containing a photopolymerization initiator, the polymerization of the energy ray-polymerizable component can proceed more efficiently.
The photopolymerization initiator includes, for example, the same photopolymerization initiators mentioned in the description of the solvent-free resin composition (y-1a).
A photoinitiator may be used individually by 1 type, and may use 2 or more types together.
The content of the photopolymerization initiator in the adhesive composition (x-2) is preferably 0.01 to 10 parts by mass, more preferably 0 parts by mass, with respect to 100 parts by mass of the total amount of the energy ray-polymerizable adhesive resin. 0.03 to 5 parts by mass, more preferably 0.05 to 3 parts by mass.

(crosslinking agent)
The cross-linking agent includes, for example, the same cross-linking agents as mentioned in the description of the pressure-sensitive adhesive composition (x-1). Among these, trimethylolpropane adduct-type modified polyisocyanate compounds are preferred, trimethylolpropane adduct-type modified aromatic polyisocyanate compounds are more preferred, and trimethylolpropane adduct-type modified tolylene diisocyanate is even more preferred. .
The content of the cross-linking agent in the pressure-sensitive adhesive composition (x-2) is appropriately adjusted according to the number of functional groups possessed by the energy-ray-polymerizable adhesive resin. parts, preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 5 parts by mass.

(Tackifier)
The adhesive composition (x-2) may further contain a tackifier from the viewpoint of further improving adhesive strength. The tackifier includes, for example, the same tackifiers mentioned in the description of the adhesive composition (x-1).

(Adhesive additive)
The pressure-sensitive adhesive composition (x-2) may contain additives for pressure-sensitive adhesives used in general pressure-sensitive adhesives, in addition to the additives described above, within a range that does not impair the effects of the present invention. .
As the adhesive additive, for example, the same ones as those mentioned in the description of the adhesive composition (x-1) can be mentioned.

(Thickness of second adhesive layer (X2))
The thickness of the second pressure-sensitive adhesive layer (X2) is preferably 5-150 μm, more preferably 8-100 μm, still more preferably 12-70 μm, still more preferably 15-50 μm.
When the thickness of the second pressure-sensitive adhesive layer (X2) is within the above range, there is a tendency that the workpiece can be fixed satisfactorily.

<Release material>
As the release material, a release sheet subjected to double-sided release treatment, a release sheet subjected to single-sided release treatment, or the like is used.
Base materials for the release material include, for example, plastic films and papers. Examples of plastic films include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; olefin resin films such as polypropylene resin and polyethylene resin; , glassine paper, kraft paper, and the like.

Examples of release agents include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins; long-chain alkyl-based resins, alkyd-based resins, fluorine-based resins, and the like. The release agent may be used alone or in combination of two or more.

Specific embodiments of the method for manufacturing a semiconductor device will be described below.
<Method for Manufacturing Semiconductor Device of First Aspect>
In the method for manufacturing a semiconductor device according to the first aspect, a double-sided pressure-sensitive adhesive sheet in which the expansion start temperature (t) of the thermally expandable particles is a predetermined temperature (for example, 50° C. or more and less than 125° C.) is used as the double-sided pressure-sensitive adhesive sheet, A manufacturing method including the following steps 1 to 7 can be mentioned. It should be noted that the numbers representing the process names are given to distinguish each process, and do not necessarily represent that they are executed in this order.

- Step 1: A step of attaching an object to be processed to the second adhesive layer (X2) and attaching a support to the first adhesive layer (X1) - Step 2: The second adhesive layer of the object to be processed (X2) Forming a groove, which is a line to be divided, on the surface to be attached to (X2), and Forming a modified region, which is a line to be divided, inside the object before the back surface grinding step. A step of performing at least one of the steps (dividing preliminary step)
Step 3: With the support attached to the first adhesive layer (X1) and the object to be processed attached to the second adhesive layer (X2), the support and the first adhesive layer ( A step of irradiating the second pressure-sensitive adhesive layer (X2) with an energy ray through X1) (energy ray irradiation step)
Step 4: With the support attached to the first adhesive layer (X1) and the object to be processed attached to the second adhesive layer (X2), the second adhesive on the object to be processed A step of performing a back grinding process for grinding the surface opposite to the surface attached to the layer (X2) (back grinding step)
・Step 5: Step of attaching a thermosetting film to the surface of the processed object opposite to the second adhesive layer (X2) ・Step 6: Start the expansion of the double-sided adhesive sheet A step of heating to a temperature (t) or higher to separate the first pressure-sensitive adhesive layer (X1) from the support (first separation step)
- Step 7: A step of separating the second adhesive layer (X2) and the object to be processed (second separation step)

A method for manufacturing a semiconductor device including steps 1 to 7 will be described below with reference to the drawings. In the following description, an example in which a semiconductor wafer is used as an object to be processed will be mainly described, but the same applies to other objects to be processed.

(Step 1)
Step 1 is a step of attaching an object to be processed to the second pressure-sensitive adhesive layer (X2) of the double-sided pressure-sensitive adhesive sheet, and attaching a support to the first pressure-sensitive adhesive layer (X1).
In step 1, there are no particular restrictions on the order in which the object to be processed and the support are attached to the double-sided pressure-sensitive adhesive sheet. The support may be attached, or the object may be attached to the second adhesive layer (X2) after the support is attached to the first adhesive layer (X1). Both may be attached at the same time. Considering that the circuit surface of the object to be processed is attached to the second pressure-sensitive adhesive layer (X2), it is preferable to attach the double-sided sheet to the object to be processed without attaching a support to the double-sided pressure-sensitive adhesive sheet. It is preferable to apply the support to the first pressure-sensitive adhesive layer (X1) after applying the object to be processed to the second pressure-sensitive adhesive layer (X2).

FIG. 2 shows a cross-sectional view for explaining the steps of attaching the semiconductor wafer W to the second adhesive layer (X2) of the double-sided adhesive sheet 1a and attaching the support 3 to the first adhesive layer (X1). It is
The semiconductor wafer W is attached so that the front surface W1, which is the circuit surface, faces the second adhesive layer (X2).
The semiconductor wafer W may be a silicon wafer, or a wafer of gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or the like.
The thickness of the semiconductor wafer W before grinding is usually 500 to 1,000 μm.
The circuit on the surface W1 of the semiconductor wafer W can be formed by conventional methods such as etching and lift-off.

The material of the support 3 may be appropriately selected according to the type of object to be processed, the details of processing, etc., taking into consideration the required properties such as mechanical strength and heat resistance.
Materials for the support 3 include, for example, nonmetallic inorganic materials such as glass and quartz; epoxy resins, ABS resins, acrylic resins, engineering plastics, super engineering plastics, polyimide resins, polyamideimide resins, and the like having energy ray transmittance. Resin material: Composite materials having energy ray transmittance such as glass epoxy resin, etc., can be mentioned, and among these, glass is preferred.
Examples of the engineering plastic include nylon, polycarbonate (PC), polyethylene terephthalate (PET), and the like.
Examples of the super engineering plastics include polyphenylene sulfide (PPS), polyethersulfone (PES), polyetheretherketone (PEEK), and the like.

The support 3 is preferably attached to the entire adhesive surface of the first adhesive layer (X1). Therefore, the area of the surface of the support 3 on the side to be attached to the adhesive surface of the first adhesive layer (X1) is preferably equal to or greater than the area of the adhesive surface of the first adhesive layer (X1). Moreover, the surface of the support 3 on the side to be attached to the adhesive surface of the first adhesive layer (X1) is preferably planar.
Although the shape of the support 3 is not particularly limited, it is preferably plate-like.
The thickness of the support 3 is preferable from the viewpoint of being able to satisfactorily support the object to be processed during the back surface grinding process and the processed object after the back surface grinding process, and to ensure the transparency of energy rays. is 0.1 mm or more and 5 mm or less, more preferably 0.5 mm or more and 3 mm or less.

(Step 2) Singulation Preliminary Step Step 2 corresponds to the singulation preliminary step described above. In step 2, before the step of forming a groove, which is a planned division line, on the surface of the object to be processed on the side to be attached to the second adhesive layer (X2), and the step of grinding the back surface, the processing is performed. at least one of the steps of forming a modified region, which is a line to be divided, inside the object. Process 2 is performed before process 3 (back surface grinding process).
The grooves can be formed by dicing using a wafer dicing machine equipped with a dicing blade.
The modified region is formed inside the object by irradiating a laser beam focused on the inside of the object. The incident surface of the laser beam may be the front surface or the back surface of the object to be processed, but usually the laser beam is incident from the back surface. Also, the laser beam incident surface may be a surface to which a double-sided pressure-sensitive adhesive sheet is attached, in which case the laser beam is irradiated onto the object to be processed via the double-sided pressure-sensitive adhesive sheet.

FIG. 3 shows a cross-sectional view for explaining the step of forming a plurality of modified regions 5 on the semiconductor wafer W attached to the second adhesive layer (X2) using the laser beam irradiation device 4. there is
A laser beam is irradiated from the back surface W2 side of the semiconductor wafer W, and a plurality of modified regions 5 are formed inside the semiconductor wafer W at substantially equal intervals. 4 and 5 below also show an example in which a modified region is formed inside a semiconductor wafer by irradiating laser light as a preparatory step for singulation.

As will be described later, when the semiconductor wafer W is singulated by the stealth dicing method, the second adhesive layer ( A modified region may be formed in advance by irradiating the semiconductor wafer W to be attached to X2) with a laser beam, or step 2 may be performed at any stage of step 1 or after step 1. Thus, the modified region may be formed by irradiating the semiconductor wafer W attached to the second adhesive layer (X2) with laser light. From the viewpoint that the object to be processed having the embrittled portion can be held on the support from the formation of the modified region to the singulation, in step 1, the first pressure-sensitive adhesive layer (X1) It is preferable to carry out step 2 after attaching the support to the substrate.
On the other hand, as will be described later, when the semiconductor wafer W is singulated by the blade tip dicing method, by performing the step 2 prior to the step 1, the semiconductor to be stuck to the second adhesive layer (X2) in the step 1 It is preferable to form grooves in the front surface W1 of the wafer W in advance.

(Step 3) Energy beam irradiation step Step 3 corresponds to the energy beam irradiation step described above. In step 3, with the support adhered to the first pressure-sensitive adhesive layer (X1) and the object to be processed adhered to the second pressure-sensitive adhesive layer (X2), prior to step 4 below, a second By selectively starting to irradiate energy rays to a region of the second pressure-sensitive adhesive layer (X2) corresponding to a portion inside the peripheral edge of the object to be processed, the second pressure-sensitive adhesive layer (X2) Cure the area.
In the energy ray irradiation step, the energy ray irradiation may be performed only once, or may be performed in a plurality of times.

In FIG. 4(a), from the back side of the support 3, through the support 3, the first adhesive layer (X1), the base layer (Y1), and the base layer (Y2), an energy ray irradiation source A cross-sectional view for explaining the step of irradiating energy rays from 20a is shown.
Here, as shown in FIG. 4A, a mask member 30a such as a masking frame is arranged on the rear surface of the support 3 at a position corresponding to the peripheral edge Wp of the semiconductor wafer W, which is the object to be processed. there is
By irradiating energy rays from the energy ray irradiation source 20a, as shown in FIG. 4(b), a region ( X2q) is cured to become a cured region (X2q').

A region (X2q) of the second adhesive layer (X2) corresponding to the region Wq inside the peripheral portion of the semiconductor wafer is cured by the irradiation of the energy beam. As a result, the vibration of the semiconductor wafer W, which is the object to be processed, is suppressed in the back surface grinding process. The region (X2p) of the second adhesive layer (X2) corresponding to the peripheral edge of the semiconductor wafer W is masked by the mask member 30a and therefore does not harden and maintains high adhesiveness. Peeling of the portion Wp from the second adhesive layer (X2) is also prevented.
Although the adhesiveness of the region (X2q') decreases due to curing, it still maintains a certain degree of adhesiveness to the semiconductor wafer W, and the adhesiveness of the region (X2p) corresponding to the peripheral edge remains. Since the adhesive sheet as a whole can be easily fixed to the object to be processed, peeling of the semiconductor wafer W, which is the object to be processed, from the second adhesive layer (X2) during the back grinding process is suppressed.
In addition, before the back surface grinding step, the energy beam is not irradiated, the first pressure-sensitive adhesive layer (X1) and the support are separated by heating in the first separation step, and then the double-sided pressure-sensitive adhesive sheet is separated in the second separation step. In the case of the method of manufacturing a semiconductor device in which energy rays are irradiated onto the double-sided adhesive sheet, the energy ray transmittance of the double-sided pressure-sensitive adhesive sheet is lowered due to the expansion of the thermally expandable particles in the first separation step. For this reason, in the second separation step, when the semiconductor wafer W is separated from the second adhesive layer (X2), insufficient irradiation of the energy beam may cause peeling failure, or the irradiation time of the energy beam for separation may be Prolonged problems are likely to occur. In the method for manufacturing a semiconductor device according to the present embodiment, the second adhesive layer (X2) is irradiated with energy rays before the first separation step, so the above problem does not occur.

As the energy ray irradiation source 20a, for example, one having an ultraviolet light source such as an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, or UV-LED, or one having an electron beam source such as an electron beam accelerator can be used. .
Considering that the support 3 has a certain thickness, as shown in FIG. 4, when a masking means such as a mask member is arranged on the side of the support 3 opposite to the side in contact with the double-sided adhesive sheet. Also, in order to irradiate the target area with the energy beam as accurately as possible, it is preferable to use a straight energy beam source such as an LED-UV lamp.

(Step 4) Backside Grinding Step Step 4 corresponds to the backside grinding step described above. Step 4 is a step of thinning the object by performing a grinding process on the object. When the singulation preliminary step is included as in the present embodiment, the workpiece is thinned and singulated by executing the back surface grinding step.
Step 4 is performed after step 3 (energy beam irradiation step) is started. Step 4 may start after step 3 is completed, or after step 3 is started and before step 3 is completed.

Examples of the back surface grinding process include a grinding process for only thinning the object to be processed; a grinding/dividing process by a blade tip dicing method and a stealth tip dicing method; and the like.
Among these, the grinding and singulation processing by the blade tip dicing method and the grinding and singulation processing by the stealth tip dicing method are suitable.

The blade tip dicing method is also called the DBG method (Dicing Before Grinding). In the blade tip dicing method, grooves are formed in the semiconductor wafer in advance to a depth shallower than the thickness thereof by performing the above-described dicing along the lines to be divided, and then the semiconductor wafer is ground so that the ground surface reaches at least the grooves. In this method, the back surface is ground until the substrate is thinned, and the substrate is divided into individual pieces. The grooves reached by the ground surface form cuts penetrating the semiconductor wafer, and the semiconductor wafer is divided by the cuts into individual semiconductor chips. The grooves formed in advance are usually provided on the surface (circuit surface) of the semiconductor wafer, and can be formed, for example, by dicing using a conventionally known wafer dicing apparatus equipped with a dicing blade.

The stealth dicing method is also called SDBG method (Stealth Dicing Before Grinding). As described above, the stealth dicing method is a type of method in which a modified region is formed inside a semiconductor wafer by irradiating a laser beam, and the semiconductor wafer is singulated using the modified region as a division starting point. Specifically, while thinning the semiconductor wafer having the modified region by back-grinding, the pressure applied to the semiconductor wafer at that time is applied to the adhesive layer of the semiconductor wafer with the modified region as a starting point. In this method, the cracks are extended by pressing and singulating the semiconductor wafer into semiconductor chips.
In addition, the grinding thickness after forming the modified region may be a thickness that reaches the modified region. Then, it may be cleaved by a processing pressure such as a grinding wheel.

5(a) and 5(b) show cross-sectional views for explaining the process of separating the semiconductor wafer W into a plurality of semiconductor chips CP while thinning it.
As shown in FIG. 5A, the rear surface W2 of the semiconductor wafer W on which the modified region 5 is formed is ground by a grinder 6. At this time, the pressure applied to the semiconductor wafer W cuts the semiconductor wafer W from the modified region 5 as a starting point. give rise to As a result, as shown in FIG. 5B, a plurality of semiconductor chips CP obtained by thinning and singulating the semiconductor wafer W are obtained.
The back surface W2 of the semiconductor wafer W formed with the modified region 5 is ground while the support 3 supporting the semiconductor wafer W is fixed on a fixed table such as a chuck table.

The thickness of the semiconductor chip CP after grinding is preferably 5 to 100 μm, more preferably 10 to 45 μm. Further, when the grinding process and the singulation process are performed by the stealth dicing method, the thickness of the semiconductor chip CP obtained by grinding can be easily set to 50 μm or less, more preferably 10 to 45 μm.
The size of the semiconductor chip CP after grinding in plan view is preferably less than 600 mm ² , more preferably less than 400 mm ² , and still more preferably less than 300 mm ² . The size of the semiconductor chip CP in plan view may be preferably 1 mm ² or more, more preferably 5 mm ² or more, and even more preferably 10 mm ² or more. In addition, planar view means viewing in a thickness direction.
The shape of the semiconductor chip CP after singulation in plan view may be a square or an elongated shape such as a rectangle.
If the double-sided pressure-sensitive adhesive sheet used in the method for manufacturing a semiconductor device according to the first embodiment has thermally expandable particles whose expansion start temperature (t) is 50° C. or higher, temperature rise during grinding or the like causes A situation in which the thermally expandable particles unintentionally expand can be avoided. Therefore, unintended separation, displacement, etc. of the object to be processed can be suppressed.

(Step 5)
Step 5 is a step of attaching a thermosetting film to the surface of the processed object opposite to the second pressure-sensitive adhesive layer (X2).
FIG. 6 shows a step of attaching a thermosetting film 7 provided with a support sheet 8 to the surface of a plurality of semiconductor chips CP obtained by performing the above treatment, on the side opposite to the second adhesive layer (X2). A cross-sectional view illustrating the is shown.

The thermosetting film 7 is a thermosetting film obtained by forming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting the semiconductor chip CP on a substrate. The thermosetting film 7 may contain a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc., if necessary.
As the thermosetting film 7, for example, a thermosetting film that is generally used as a die bonding film, a die attach film, or the like can be used.
The thickness of the thermosetting film 7 is not particularly limited, but is usually 1-200 μm, preferably 3-100 μm, more preferably 5-50 μm.
The support sheet 8 can support the thermosetting film 7. For example, the support sheet 8 includes resins, metals, Paper materials, etc. are mentioned.

As a method of attaching the thermosetting film 7 to the plurality of semiconductor chips CP, for example, there is a lamination method.
Lamination may be performed with heating or without heating. The heating temperature in the case of laminating while heating is preferably "a temperature lower than the expansion start temperature (t)" from the viewpoint of suppressing the expansion of the thermally expandable particles and the viewpoint of suppressing the thermal change of the adherend. It is preferably "expansion start temperature (t) -5°C" or lower, more preferably "expansion start temperature (t) -10°C" or lower, still more preferably "expansion start temperature (t) -15°C" or lower.

(Step 6) First Separation Step Step 6 is a step of heating the double-sided pressure-sensitive adhesive sheet to the expansion initiation temperature (t) or higher to separate the first pressure-sensitive adhesive layer (X1) and the support.
FIG. 7 shows a cross-sectional view for explaining the process of heating the double-sided pressure-sensitive adhesive sheet 1a to separate the first pressure-sensitive adhesive layer (X1) and the support 3. As shown in FIG.

The heating temperature in the first separation step is equal to or higher than the expansion start temperature (t) of the thermally expandable particles, preferably "a temperature higher than the expansion start temperature (t)", more preferably "expansion start temperature (t) + 2 ° C. above, more preferably above "expansion start temperature (t) + 4°C", still more preferably above "expansion start temperature (t) + 5°C". In addition, the heating temperature in the first separation step is preferably "expansion start temperature (t) + 50 ° C." or less, more preferably "expansion start temperature temperature (t) + 40°C" or less, more preferably "expansion start temperature (t) + 20°C" or less.
The upper limit of the heating temperature in the first separation step is preferably 120° C. or less, more preferably 115° C. or less, even more preferably 110° C. or less, and even more preferably 105° C., from the viewpoint of suppressing thermal change of the adherend. It is below.

(Step 7) Second Separation Step Step 7 is a step of separating the second pressure-sensitive adhesive layer (X2) and the object to be processed.
FIG. 8 shows a cross-sectional view for explaining the step of separating the second adhesive layer (X2) and the plurality of semiconductor chips CP.
A method for separating the second adhesive layer (X2) and the plurality of semiconductor chips CP may be appropriately selected according to the type of the second adhesive layer (X2). For example, the region of the second pressure-sensitive adhesive layer (X2) facing the peripheral edge of the object to be processed may be irradiated with energy rays to reduce the adhesive strength of the region before separation. Such energy beam irradiation can be performed, for example, in the same manner as in step 3 except that the mask member 30a is not used.
The energy beam irradiation to the region of the second pressure-sensitive adhesive layer (X2) facing the peripheral edge of the object to be processed may be performed in this step, or the thermally expandable particles in the first separation step may be irradiated with energy rays. From the viewpoint of avoiding a reduction in the energy ray transmittance of the double-sided pressure-sensitive adhesive sheet due to expansion, the back grinding process may be performed before the first separation process is started.

A plurality of semiconductor chips CP attached to the thermosetting film 7 are obtained through the above steps 1 to 7. FIG.
Next, it is preferable to obtain semiconductor chips CP with thermosetting films 7 by dividing the thermosetting film 7 to which a plurality of semiconductor chips CP are attached in the same shape as the semiconductor chips CP. As a method for dividing the thermosetting film 7, for example, a method such as laser dicing, expansion, or fusing using a laser beam can be applied.
FIG. 9 shows a semiconductor chip CP with a thermosetting film 7 divided on the support sheet 8 into the same shape as the semiconductor chip CP. The portion positioned at the peripheral portion of the semiconductor wafer is a chip with no circuit formed thereon and is not used as a product, so it is removed from the semiconductor chip 9 shown in FIG.

The semiconductor chips CP with the thermosetting film 7 are further subjected to an expansion step of widening the interval between the semiconductor chips CP, a rearrangement step of arranging the plurality of semiconductor chips CP with widened intervals, and a plurality of semiconductor chips CP. After a reversing process for reversing the front and back of the film is appropriately performed, the film is attached (die attached) to the substrate from the thermosetting film 7 side. After that, the semiconductor chip and the substrate can be fixed by thermosetting the thermosetting film.

<Methods for Manufacturing Semiconductor Devices of Second to Fourth Aspects>
In the above-described step 3 (energy beam irradiation step), various methods can be employed other than using the mask member 30a as shown in FIG. Hereinafter, semiconductor device manufacturing methods in which the energy beam irradiation process of the first mode is changed from the first mode will be described as the semiconductor device manufacturing methods of the second to fourth modes.

FIG. 10 is a schematic diagram of step 3 in the method of manufacturing a semiconductor device according to the second embodiment, and is a schematic cross-sectional diagram showing an example in which a masking layer 30b is patterned on the back surface of the support 3 by printing or the like. As shown in FIG. 10, by providing a patterned masking layer 30b and masking the region of the second adhesive layer (X2) corresponding to the periphery of the semiconductor wafer W, the support 3 and the masking layer 30b are bonded together. It becomes difficult for a gap to occur between and, and it becomes easy to prevent leakage of energy rays. In addition, since the thickness of the masking layer 30b can be easily reduced, it becomes easier to avoid the contact of the energy beam irradiation source with the masking layer 30b, thereby improving the ease of manufacture.
Also, instead of forming the masking layer by printing, a masking sheet patterned in advance may be used and attached to the back surface of the support to form the masking layer.

FIG. 11 is a schematic diagram of step 3 in the method for manufacturing a semiconductor device according to the third embodiment, in which a highly straight energy ray irradiation source such as UV-LED is used as the energy ray irradiation source, and installation of a mask is omitted. It is a cross-sectional schematic diagram which shows the example which carried out. By using the energy ray irradiation source 20b with high straightness, it is possible to selectively irradiate the energy ray to a required area, and the need for providing a mask is eliminated. Therefore, the manufacturing process of the semiconductor device can be simplified. In this embodiment, it is desirable to dispose the energy ray irradiation source 20b as close to the support 3 as possible.

FIG. 12 is a schematic diagram of Step 3 in the method for manufacturing a semiconductor device according to the fourth aspect, and is a schematic cross-sectional view showing another example using an energy ray irradiation source with high straightness as the energy ray irradiation source. As shown in FIG. 12, by providing the cover 21 covering the energy beam irradiation source 20b along the peripheral edge Wp of the semiconductor wafer which is the object to be processed, compared to the semiconductor device manufacturing method of the third aspect, The region (X2p) of the second pressure-sensitive adhesive layer (X2) facing the peripheral edge of the object to be processed is less likely to be irradiated with energy rays.

1a, 1b, 1c double-sided adhesive sheet 3 support 4 laser beam irradiation device 5 modified region 6 grinder 7 thermosetting film 8 support sheet 20a, 20b energy beam irradiation source 21 cover 30a mask member 30b masking layer W semiconductor wafer (processing Object)
W1 Circuit surface of semiconductor wafer W2 Back surface of semiconductor wafer CP Semiconductor chip Wp Peripheral portion of semiconductor wafer Wq Portion inside the peripheral portion of semiconductor wafer (X1) First adhesive layer (X1)
(X2) Second adhesive layer (X2)
(X2p) A region (X2q) of the second pressure-sensitive adhesive layer (X2) facing the peripheral edge of the workpiece (X2q) A region of the second pressure-sensitive adhesive layer (X2) facing a portion inside the peripheral edge of the workpiece (X2q′) Cured region (Y1) of second pressure-sensitive adhesive layer (X2) Thermally expandable base layer (Y1)
(Y2) Non-thermally expandable base layer (Y2)

Claims (7)

A first pressure-sensitive adhesive layer (X1) as an outer layer on one side and a second pressure-sensitive adhesive layer (X2) as an outer layer on the other side, wherein the second pressure-sensitive adhesive layer (X2) is energy ray cured using a double-sided adhesive sheet with
A support having energy ray transparency is attached to the first adhesive layer (X1), and an object to be processed is attached to the second adhesive layer (X2). a back surface grinding step of grinding the surface opposite to the surface attached to the agent layer (X2);
Before the back surface grinding step, the support and the first pressure-sensitive adhesive layer (X1) are adhered to the first pressure-sensitive adhesive layer (X1) and the object to be processed is adhered to the second pressure-sensitive adhesive layer (X2) . By selectively starting to irradiate the region of the second pressure-sensitive adhesive layer (X2) via the pressure-sensitive adhesive layer (X1) corresponding to the portion inside the peripheral edge of the object to be processed with energy rays, A method for manufacturing a semiconductor device, comprising an energy beam irradiation step of curing the region of the second pressure-sensitive adhesive layer (X2). The double-sided pressure-sensitive adhesive sheet further comprises a base layer (Y), has a first pressure-sensitive adhesive layer (X1) on one main surface of the base layer, and has the other main surface of the base layer (Y). 2. The method of manufacturing a semiconductor device according to claim 1, further comprising a second adhesive layer (X2) thereon. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the substrate layer (Y) is a thermally expandable layer containing thermally expandable particles. 4. The method for manufacturing a semiconductor device according to claim 1, wherein the first adhesive layer (X1) is a thermally expandable layer containing thermally expandable particles. 5. The manufacture of the semiconductor device according to claim 3, wherein the support is separated from the first pressure-sensitive adhesive layer (X1) by heating the double-sided pressure-sensitive adhesive sheet after the energy beam irradiation step and the back surface grinding step. Method. As a preliminary step for singulation of the object to be processed,
A step of forming grooves, which are planned division lines, on the surface of the object to be processed on the side to be attached to the second adhesive layer (X2) before the back surface grinding step;
6. The semiconductor according to any one of claims 1 to 5, further comprising at least one step of forming a modified region, which is a line to be divided, inside said object before said back surface grinding step. Method of manufacturing the device. 7. The semiconductor device according to claim 1, wherein in said energy beam irradiation step, energy beam irradiation is performed by masking a region of said support corresponding to a peripheral edge of said object to be processed. manufacturing method.

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