WO2019216262A1

WO2019216262A1 - Method of manufacturing semiconductor chip

Info

Publication number: WO2019216262A1
Application number: PCT/JP2019/017875
Authority: WO
Inventors: 忠知山田; 真也田久
Original assignee: リンテック株式会社
Priority date: 2018-05-07
Filing date: 2019-04-26
Publication date: 2019-11-14
Also published as: TWI808170B; KR20210006896A; JPWO2019216262A1; CN112088421A; JP7241744B2; TW202003771A

Abstract

Provided is a method of manufacturing a semiconductor chip that comprises the following steps (1) to (3) using an adhesive sheet which includes a base (Y) having an expandable base layer (Y1) containing expandable particles and a non-expandable base layer (Y2), and on respective sides of the base (Y), a first adhesive layer (X1) in which protrusions may form in the adhesive surface , due to the expansion of the expandable particles, and a second adhesive layer (X2). ∙ Step (1): A step of affixing the first adhesive layer (X1) to a hard support and affixing the second adhesive layer (X2) to the surface of a semiconductor wafer. ∙ Step (2): A step of obtaining a plurality of semiconductor chips. ∙ Step (3): A step of expanding the expandable particles and separating the hard support from the first adhesive layer (X1) at an interface P.

Description

Manufacturing method of semiconductor chip

The present invention relates to a method for manufacturing a semiconductor chip.

In a semiconductor chip manufacturing process, various processes are often performed in a state where a semiconductor wafer is attached to a support using an adhesive sheet.
The pressure-sensitive adhesive sheet used at this time is required to have a property that the semiconductor wafer can be sufficiently fixed at the time of processing and can be easily peeled off from the support after the processing.
A heat-peelable pressure-sensitive adhesive sheet having a heat-expandable pressure-sensitive adhesive layer containing heat-expandable particles is known as a pressure-sensitive adhesive sheet that can meet such requirements.

For example, in Patent Document 1, a thermally expandable adhesive layer is prepared by using a thermally expandable adhesive layer including thermally expandable microspheres on one side of a substrate and a heat-peelable double-sided adhesive sheet provided with an adhesive layer on the other side. A method is disclosed in which an adherend such as a wafer is adhered to a support and an adherend such as a wafer is bonded to the other adhesive layer to process the adherend.
According to Patent Document 1, by using the above-described heat-peelable double-sided pressure-sensitive adhesive sheet, the smoothness of the adherend surface can be maintained during processing of the adherend, and after processing, the double-sided pressure-sensitive adhesive sheet is peeled off. The stress can be reduced, and it can be easily peeled without damaging the adherend.

JP 2003-292916 A

In the method for processing an adherend described in Patent Document 1, the thermally expandable adhesive layer of the above double-sided pressure-sensitive adhesive sheet is attached to a support, and the adherend is attached to the other adhesive layer. Is processed.
However, since the heat-expandable pressure-sensitive adhesive layer included in the double-sided pressure-sensitive adhesive sheet used in the processing method of Patent Document 1 contains heat-expandable microspheres, the support is more suitable than a pressure-sensitive adhesive layer that does not contain heat-expandable microspheres. There is concern about a decrease in adhesive strength.
The decrease in the adhesive strength with the support causes various adverse effects due to the fact that the adherend is not sufficiently fixed to the support. For example, chip processing methods such as the tip dicing method and stealth dicing method, which grind the back surface of the wafer and divide it into chips, are not sufficiently fixed to the support, and the resulting chip has a bad edge. Can occur.

Moreover, in patent document 1, when peeling a double-sided adhesive sheet from a support body, a thermal expansion microsphere is expanded by heat processing, an unevenness | corrugation is formed in the surface of a thermally expandable adhesion layer, and a support body is used. By reducing the contact area, the adhesive force is reduced and peeling occurs.
However, in the above peeling method, when peeling the double-sided pressure-sensitive adhesive sheet from the support, some adhesive force may remain, so that peeling may be difficult. In addition, a part of the heat-expandable adhesive layer may remain on the surface of the support after peeling, which requires a cleaning process for the support, which causes a decrease in productivity.
In order to prevent contamination of the support, it may be possible to select a low-adhesive resin as the adhesive resin constituting the thermally expandable adhesive layer. At the time of processing the adherend, there may be a problem that the adherend is not sufficiently fixed to the adherend.

The present invention improves the yield by suppressing chipping of the end of the semiconductor chip, etc., and when separating the support and the attached adhesive sheet, it can be easily separated at once and the support after separation. An object of the present invention is to provide a method for manufacturing a semiconductor chip, which can suppress contamination of the body and can eliminate the step of cleaning the support.

In the process of manufacturing a semiconductor chip by dividing a semiconductor wafer, the present inventors respectively provide a first adhesive on both surfaces of a base material including at least an inflatable base material layer containing inflatable particles and a non-inflatable base material layer. It has been found that the above-mentioned problems can be solved by using an adhesive sheet having an adhesive layer and a second adhesive layer.

That is, the present invention relates to the following [1] to [11].
[1] A substrate (Y) comprising at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2);
On both surfaces of the substrate (Y), each has a first pressure-sensitive adhesive layer (X1) and a second pressure-sensitive adhesive layer (X2),
A method for producing a semiconductor chip from a semiconductor wafer using a pressure-sensitive adhesive sheet, in which unevenness may occur on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) due to expansion of the expandable particles,
A method for producing a semiconductor chip, comprising the following steps (1) to (3).
Step (1): A step of sticking the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) to the hard support and sticking the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) to the surface of the semiconductor wafer.
Step (2): A step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The interface between the hard support and the first pressure-sensitive adhesive layer (X1) while the expandable particles are expanded and the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are adhered. Separating with P.
[2] The pressure-sensitive adhesive sheet has a first pressure-sensitive adhesive layer (X1) on the base material (Y) on the side of the expandable base material layer (Y1), and the base material (Y) has the non-expandable group. The method for producing a semiconductor chip according to [1], wherein the second pressure-sensitive adhesive layer (X2) is provided on the material layer (Y2) side.
[3] The base material (Y) is a non-expandable base material provided on the expandable base material layer (Y1) and the first adhesive layer (X1) side of the expandable base material layer (Y1). A layer (Y2-1) and a non-intumescent substrate layer (Y2-2) provided on the second adhesive layer (X2) side of the expandable substrate layer (Y1),
The storage elastic modulus E ′ of the non-expandable base layer (Y2-1) when the expandable particles expand is determined by the storage modulus of the non-expandable base layer (Y2-2) when the expandable particles expand. The method for producing a semiconductor chip according to the above [1], which is lower than the elastic modulus E ′.
[4] The non-expandable base material layer (Y2) is present at a position farther from the first pressure-sensitive adhesive layer (X1) than the expandable base material layer (Y1). The non-intumescent substrate layer (Y2) does not exist between the layer (Y1) and the first pressure-sensitive adhesive layer (X1),
The storage elastic modulus E ′ of the non-expandable base layer (Y2) when the expandable particles expand is the storage elastic modulus E of the expandable base layer (Y1) when the expandable particles expand. The method for producing a semiconductor chip according to [1] or [2], which is larger than '.
[5] Manufacture of a semiconductor chip according to any one of the above [1] to [4], wherein when the expandable particles are expanded in step (3), they are not separated between the layers constituting the pressure-sensitive adhesive sheet. Method.
[6] The method for manufacturing a semiconductor chip according to any one of [1] to [5], further comprising the following step (4).
Step (4): After separation from the hard support in Step (3), the back surface opposite to the circuit surface of the plurality of semiconductor chips is formed with a base film, an adhesive layer and / or an adhesive layer. A step of removing the pressure-sensitive adhesive sheet from the semiconductor chip after being attached to the transfer tape.
[7] The method for manufacturing a semiconductor chip according to any one of [1] to [6], wherein the expandable particles are thermally expandable particles having an expansion start temperature (t) of 60 to 270 ° C.
[8] In the above [7], the thermally expandable particles are expanded by a heat treatment between “expansion start temperature (t) + 10 ° C.” to “expansion start temperature (t) + 60 ° C.” The manufacturing method of the semiconductor chip of description.
[9] Storage of the thermally expandable substrate layer (Y1-1) at 23 ° C., wherein the expandable substrate layer (Y1) is a thermally expandable substrate layer (Y1-1) containing the thermally expandable particles. The method for producing a semiconductor chip according to [7] or [8], wherein the elastic modulus E ′ (23) is 1.0 × 10 ⁶ Pa or more.
[10] The method for manufacturing a semiconductor chip according to any one of the above [1] to [9], wherein the volume change rate (%) of the non-expandable base material layer (Y2) is less than 2% by volume.
[11] In the step (2), the semiconductor wafer having the modified region is ground on the back surface on which the circuit opposite to the circuit surface is not formed, and the semiconductor wafer is divided to obtain a plurality of semiconductor chips. The method for manufacturing a semiconductor chip according to any one of [1] to [10], which is a process.

According to the method for manufacturing a semiconductor chip of the present invention, when separating the support and the attached adhesive sheet while improving the yield by suppressing chipping or the like of the end portion of the obtained semiconductor chip, all at once. Since it can be easily separated, contamination of the support after separation can be suppressed, and the washing step of the support can be omitted, so that productivity can be improved.

It is a cross-sectional schematic diagram of the said adhesive sheet which shows an example of a structure of the adhesive sheet used with the manufacturing method of the semiconductor chip of this invention. FIG. 6 is a schematic cross-sectional view in steps (1) to (3) of the method for manufacturing a semiconductor chip of the present invention. FIG. 6 is a schematic cross-sectional view in steps (4) to (6) of the method for manufacturing a semiconductor chip of the present invention.

In this specification, the determination of whether the target layer is an “expandable layer” or “non-expandable layer” is performed after 3 minutes of processing for expansion, and before and after the processing. Judgment is made based on the volume change rate calculated from the equation.
Volume change rate (%) = {(volume of the layer after treatment−volume of the layer before treatment) / volume of the layer before treatment} × 100
That is, if the volume resistivity is 5% by volume or more, it is determined that the layer is an “expandable layer”. If the volume change rate is less than 5% by volume, the layer is a “non-expandable layer”. It is judged that.
As the “treatment for expanding”, for example, when the expandable particles are thermally expandable particles, a heat treatment for 3 minutes may be performed at the expansion start temperature (t) of the thermally expandable particles. .

In the present specification, the “active ingredient” refers to a component excluding a diluent solvent among components contained in a target composition.
Further, the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically a value measured based on the method described in the examples.

In the present specification, for example, “(meth) acrylic acid” indicates both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms.
Moreover, about the preferable numerical range (for example, range, such as content), the lower limit value and upper limit value which were described in steps can be combined independently, respectively. For example, from the description “preferably 10 to 90, more preferably 30 to 60”, “preferable lower limit (10)” and “more preferable upper limit (60)” are combined to obtain “10 to 60”. You can also

[Method of Manufacturing Semiconductor Chip of the Present Invention]
The semiconductor chip manufacturing method of the present invention (hereinafter also simply referred to as “the manufacturing method of the present invention”) includes at least an expandable base layer (Y1) and non-expandable base layer (Y2) containing expandable particles. The first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) are provided on both sides of the base material (Y) and the base material (Y), respectively. This is a method for producing a semiconductor chip from a semiconductor wafer using a pressure-sensitive adhesive sheet in which irregularities can occur on the pressure-sensitive adhesive surface of the agent layer (X1).
The production method of the present invention includes the following steps (1) to (3).
Step (1): A step of sticking the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) to the hard support and sticking the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) to the surface of the semiconductor wafer.
Step (2): A step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The interface between the hard support and the first pressure-sensitive adhesive layer (X1) while the expandable particles are expanded and the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are adhered. Separating with P.

[Configuration of pressure-sensitive adhesive sheet used in the production method of the present invention]
FIG. 1 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet showing an example of the configuration of the pressure-sensitive adhesive sheet used in the production method of the present invention.
The pressure-sensitive adhesive sheet used in the production method of the present invention includes a base (Y) having at least an expandable base layer (Y1) and a non-expandable base layer (Y2) as shown in FIG. The adhesive sheet 1a which has a 1st adhesive layer (X1) and a 2nd adhesive layer (X2) on both surfaces of a material (Y), respectively is mentioned.

Although the base material (Y) which the adhesive sheet 1a shown to Fig.1 (a) has has the structure which the expandable base material layer (Y1) and the non-expandable base material layer (Y2) laminated directly, The substrate (Y) may have a configuration other than this.
For example, like the base material (Y) of the pressure-sensitive adhesive sheet 1b shown in FIG. 1 (b), the first non-thermally expandable base material layer (Y2-1) and the 2 A configuration in which a non-thermally expandable base material layer (Y2-2) is provided may be employed.

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, a release material may be further laminated on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2).
In this configuration, a structure in which a release material having a release treatment applied to both sides is laminated on one adhesive surface of the first adhesive layer (X1) and the second adhesive layer (X2) is wound in a roll shape. It is good.
These release materials are provided to protect the adhesive surfaces of the first adhesive layer (X1) and the second adhesive layer (X2), and are removed when the adhesive sheet is used.

Also, for example, in the pressure-sensitive adhesive sheet 1a shown in FIG. 1A, the peeling force when peeling the release material laminated on the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) are laminated. When the peeling force at the time of peeling off the release material is about the same, the adhesive sheet 1a is divided along with the two release materials and peeled off by pulling both release materials outward. This may cause a negative effect.
For this reason, the release material laminated on the first pressure-sensitive adhesive layer (X1) and the release material laminated on the second pressure-sensitive adhesive layer (X2) have different peeling forces from the pressure-sensitive adhesive layer attached to each other. It is preferable to use two types of designed release materials.

By the way, the pressure-sensitive adhesive sheet used in the production method of the present invention is adjusted so that irregularities can be generated on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) by the expansion of the expandable particles.
For example, in the pressure-sensitive adhesive sheet 1a shown in FIG. 1A, the first pressure-sensitive adhesive layer (X1) is laminated on the expandable base material layer (Y1) containing expandable particles, and the non-expandable base material layer (Y2). And a second pressure-sensitive adhesive layer (X2).
In the pressure-sensitive adhesive sheet 1a, when the expandable particles in the expandable base material layer (Y1) expand, the surface of the expandable base material layer (Y1) is uneven, and the first pressure-sensitive adhesive layer is in contact with the surface. (X1) is pushed up by the irregularities, and as a result, irregularities may also occur on the adhesive surface of the first pressure-sensitive adhesive layer (X1).
In the production method of the present invention, as described in the above step (1), the adhesive surface of the first adhesive layer (X1) is affixed to a hard support.
And in said process (3), when an expandable particle is expanded, since an unevenness | corrugation arises in the adhesive surface of a 1st adhesive layer (X1) and a contact area with a hard support body decreases, a hard support body And the first pressure-sensitive adhesive layer (X1) can be easily separated together with a slight force at the interface P.
Further, when the expandable particles are expanded, they can be easily separated by a small force at the interface between the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2). You may adjust.

On the other hand, as described in the above step (1), the surface of the semiconductor wafer is attached to the adhesive surface of the second pressure-sensitive adhesive layer (X2), and in step (2), the semiconductor wafer is divided into a plurality of semiconductors. A chip. Then, as defined in the above step (3), when the expandable particles are expanded, the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are stuck and the hard support and the first pressure-sensitive adhesive are adhered. It isolate | separates in the interface P with an agent layer (X1).
That is, when separating from the hard support, the plurality of semiconductor chips are required to be held on the second pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet.
Therefore, it is preferable that the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) is adjusted so that the formation of irregularities is suppressed so that the pressure-sensitive adhesive force is not reduced even by the expansion of the expandable particles.

For example, in the pressure-sensitive adhesive sheet 1a shown in FIG. 1 (a), the non-intumescent base material layer (Y2) is provided on the surface of the expandable base material layer (Y1) opposite to the first pressure-sensitive adhesive layer (X1). The second pressure-sensitive adhesive layer (X2) is laminated on the surface of the non-expandable base material layer (Y2).
In the pressure-sensitive adhesive sheet 1a, when the expandable particles are expanded, the non-expandable base layer (Y2) is present. Therefore, the stress from the expandable base layer (Y1) side due to expansion of the expandable particles is A non-expandable base material layer (Y2) absorbs. As a result, the formation of irregularities on the adhesive surface of the second adhesive layer (X2) laminated on the non-expandable base material layer (Y2) is suppressed, and the semiconductor chip attached to the adhesive surface can be held. .

In the pressure-sensitive adhesive sheet 1b shown in FIG. 1B, when the expandable particles expand, the first non-expandable so that irregularities are formed on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1). It is preferable to adjust the storage elastic modulus E ′ of the base material layer (Y2-1) to be low.
On the other hand, when the expandable particles expand, the second non-thermally expandable base material layer (Y2-2) is prevented from forming irregularities on the adhesive surface of the second pressure-sensitive adhesive layer (X2). The storage elastic modulus E ′ is preferably adjusted to be high.
That is, the storage elastic modulus E ′ of the first non-expandable base layer (Y2-1) when the expandable particles expand is the same as the second non-thermally expandable base layer (Y2) when the expandable particles expand. -2) is preferably adjusted to be lower than the storage elastic modulus E ′.

By the way, using the double-sided pressure-sensitive adhesive sheet having an expandable pressure-sensitive adhesive layer containing expandable particles as described in Patent Document 1, the expandable pressure-sensitive adhesive layer is stuck to a hard support, and the other pressure-sensitive adhesive layer. When manufacturing a semiconductor chip by attaching a semiconductor wafer thereon, the expandable pressure-sensitive adhesive layer to be bonded to the hard support contains expandable particles, so that the adhesive force tends to be insufficient.

The semiconductor wafer is not sufficiently fixed to the hard support due to a decrease in the adhesive force of the expandable pressure-sensitive adhesive layer to the hard support. For example, when the semiconductor wafer is divided to obtain a plurality of semiconductor chips, Defects such as chipped edges are likely to occur.
Further, in the manufacture of semiconductor chips by the stealth dicing (registered trademark, hereinafter the same) method, it is necessary to provide a modified region inside the semiconductor wafer, but as the number of modified regions increases, the semiconductor wafer warps. It becomes easy. Here, if the semiconductor wafer is not sufficiently fixed to the hard support, the warping of the semiconductor wafer cannot be suppressed, which causes a chip crack or the like.

On the other hand, it is also conceivable to avoid the above-described adverse effects by selecting an adhesive resin and making the adhesive layer to which the semiconductor wafer is attached and the expandable adhesive layer have high adhesive strength.
However, when the pressure-sensitive adhesive layer to which the semiconductor wafer is attached has a high pressure-sensitive adhesive force, it may be difficult to peel the obtained plurality of semiconductor chips from the pressure-sensitive adhesive layer.
Further, when the expandable pressure-sensitive adhesive layer has a high adhesive force, when the double-sided pressure-sensitive adhesive sheet is peeled off from the hard support by expanding the expandable particles, one of the expandable pressure-sensitive adhesive layers is formed on the surface of the hard support. Part may remain, and it is necessary to perform a washing step of the support, which causes a decrease in productivity. Moreover, when peeling the double-sided pressure-sensitive adhesive sheet affixed to the hard support, a certain amount of force is required, and it may be difficult to easily peel off at once.

On the other hand, the pressure-sensitive adhesive sheet used in the production method of the present invention has a base material (Y) having at least an inflatable base material layer (Y1) containing inflatable particles and a non-inflatable base material layer (Y2), and is inflated. When the adhesive particles expand, the adhesive surface of the first pressure-sensitive adhesive layer (X1) is adjusted so that irregularities are formed.
Therefore, the first pressure-sensitive adhesive layer (X1) to be attached to the hard support does not need to contain expandable particles, so that the semiconductor wafer can be sufficiently fixed to the hard support and the chip end portion is missing. And the like can be effectively suppressed, and the yield can be improved.
In addition, when separating the hard support and the adhesive sheet affixed, they can be easily separated at once, and the contamination of the hard support after separation is suppressed, and the cleaning process of the support is omitted. And can improve productivity.
Furthermore, the freedom degree of selection of the adhesive composition which is a forming material of a 1st adhesive layer (X1) and a 2nd adhesive layer (X2) is also high.

[Various physical properties of adhesive sheet]
The pressure-sensitive adhesive sheet used in one embodiment of the present invention has irregularities on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) attached to the hard support due to the expansion of the expandable particles, and the hard support and the first pressure-sensitive adhesive. At the interface P with the layer (X1), separation can be easily performed at a time with a slight force.
Here, in the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the peeling force (F ₁ ) when the expandable particles are expanded and separated at the interface P is usually 0 to 2000 mN / 25 mm, preferably 0 to 1000 mN / It is 25 mm, more preferably 0 to 150 mN / 25 mm, still more preferably 0 to 100 mN / 25 mm, and still more preferably 0 to 50 mN / 25 mm.
Note that the peel force (F ₁₎ is in the case of 0 mN / 25 mm, even trying to measure the peel strength by the method described in Example, includes the case where the measurement impossible because peel strength is too small.

On the other hand, before the expansion of the expandable particles, when manufacturing a plurality of semiconductor chips from a semiconductor wafer, the first pressure-sensitive adhesive layer is used from the viewpoint of suppressing the occurrence of chipping at the ends of the chips and improving the yield. The higher the adhesive strength of (X1), the better.
From the above viewpoint, in the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the peeling force (F ₀ ) when separating at the interface P before the expansion of the expandable particles is preferably 0.05 to 10.0 N / 25 mm, More preferably, it is 0.1 to 8.0 N / 25 mm, still more preferably 0.15 to 6.0 N / 25 mm, and still more preferably 0.2 to 4.0 N / 25 mm.
Incidentally, the release force (F ₀₎ can also be regarded as the adhesive strength of the first adhesive layer to the rigid support member (X1).

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the ratio [(F ₁ ) / (F ₀ )] of the peel force (F ₁ ) to the peel force (F ₀ ) is preferably 0 to 0.9, more preferably Is 0 to 0.8, more preferably 0 to 0.5, and still more preferably 0 to 0.2.

The release force (F ₁₎ is a value measured under the environment when the expandable particles are expanded. For example, when the expandable particles are thermally expandable particles, the temperature condition for measuring the peel force (F ₁ ) may be equal to or higher than the expansion start temperature (t) of the thermally expandable particles.
On the other hand, the temperature condition for measuring the peeling force (F ₀ ) may be any temperature at which the expandable particles do not expand, and is basically room temperature (23 ° C.).
However, more specific measurement conditions and measurement methods for the peel force (F ₁ ) and the peel force (F ₀ ) are based on the methods described in the examples.

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the adhesive strength of the second pressure-sensitive adhesive layer (X2) at room temperature (23 ° C.) is preferably 0.1 to 10.0 N / 25 mm, more preferably 0. The range is from 0.2 to 8.0 N / 25 mm, more preferably from 0.4 to 6.0 N / 25 mm, still more preferably from 0.5 to 4.0 N / 25 mm.
In the present specification, the adhesive strength of the second pressure-sensitive adhesive layer (X2) means a value measured by the method described in Examples.
Hereinafter, each layer which comprises the adhesive sheet used by 1 aspect of this invention is demonstrated.

<Base material (Y)>
The base material (Y) included in the pressure-sensitive adhesive sheet used in one embodiment of the present invention includes at least an expandable base material layer (Y1) containing inflatable particles and a non-expandable base material layer (Y2).
Moreover, as a base material (Y), like the adhesive sheet 1a shown to Fig.1 (a), an expandable base material layer (Y1) and a non-expandable base material layer (Y2) are each laminated | stacked one by one. As in the pressure-sensitive adhesive sheet 1b shown in FIG. 1B, the first non-thermally expandable base layer (Y2-1) and the second non-expandable base layer (Y2-1) are formed on both sides of the expandable base layer (Y1). A configuration in which a non-thermally expandable base material layer (Y2-2) is provided may be employed.

In addition, the base material (Y) included in the pressure-sensitive adhesive sheet used in one embodiment of the present invention has a configuration in which an adhesive layer is provided between the expandable base material layer (Y1) and the non-expandable base material layer (Y2). May be.
For example, in the case of the configuration of the pressure-sensitive adhesive sheet 1b shown in FIG. 1B, the expandable substrate layer (Y1), the first non-thermally expandable substrate layer (Y2-1), and / or the second non-thermally expandable layer An adhesive layer may be provided between the conductive base material layer (Y2-2).
By providing the adhesive layer, the interlayer adhesion between the expandable base material layer (Y1) and the non-expandable base material layer (Y2) can be improved.
The adhesive layer can be formed from a general adhesive or a pressure-sensitive adhesive composition that is a material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2).

In one embodiment of the present invention, the expansion of the expandable particles causes unevenness on the adhesive surface of the first pressure-sensitive adhesive layer (X1), while suppressing formation of unevenness on the adhesive surface of the second pressure-sensitive adhesive layer (X2). From the viewpoint of forming a pressure-sensitive adhesive sheet, it is preferable that the base material (Y) is provided with at least an inflatable base material layer (Y1) and a non-expandable base material layer (Y2) on the outermost surface. .
As the said aspect, the base material (Y) which the adhesive sheet 1a shown to Fig.1 (a) has, an expandable base material layer (Y1), an adhesive bond layer, and a non-expandable base material layer (Y2) are this order. The base material (Y) etc. which are laminated | stacked with are mentioned.
Examples of the material for forming the adhesive layer include the same adhesive composition as the material for forming the adhesive layer included in the transfer tape described below.

The expandable substrate layer (Y1) and the non-expandable substrate layer (Y2) constituting the substrate (Y) are both non-adhesive layers.
In the present invention, the determination as to whether or not the layer is a non-adhesive layer can be made if the probe tack value measured in accordance with JIS Z0237: 1991 is less than 50 mN / 5 mmφ with respect to the surface of the target layer. Is judged as a “non-sticky layer”.
The probe tack values on the surfaces of the expandable base material layer (Y1) and the non-expandable base material layer (Y2) of the pressure-sensitive adhesive sheet (I) used in one embodiment of the present invention are each independently usually less than 50 mN / 5 mmφ. However, it is preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and even more preferably less than 5 mN / 5 mmφ.
In addition, in this specification, the specific measuring method of the probe tack value in the surface of a thermally expansible base material is based on the method as described in an Example.

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the thickness of the substrate (Y) is preferably 15 to 2000 μm, more preferably 25 to 1500 μm, still more preferably 30 to 1000 μm, and still more preferably 40 to 500 μm. is there.

The thickness of the expandable substrate (Y1) before expansion of the expandable particles is preferably 10 to 1000 μm, more preferably 20 to 700 μm, still more preferably 25 to 500 μm, and still more preferably 30 to 300 μm.
The thickness of the non-expandable substrate (Y2) is preferably 10 to 1000 μm, more preferably 20 to 700 μm, still more preferably 25 to 500 μm, and still more preferably 30 to 300 μm.
In the present specification, for example, a plurality of expandable substrates (Y1) or non-expandable substrates (Y2) exist via other layers as in the adhesive sheet 1b shown in FIG. 1 (b). When doing, the thickness of said expansible base material (Y1) or a non-expandable base material (Y2) means the thickness per each layer.

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the thickness ratio between the expandable base material layer (Y1) and the non-thermally expandable base material layer (Y2) before expansion of the expandable particles [(Y1) / ( Y2)] is preferably 0.02 to 200, more preferably 0.03 to 150, and still more preferably 0.05 to 100.

In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, the expandable base material layer (Y1) before expansion of the expandable particles, and the first pressure-sensitive adhesive layer (X1) directly laminated with the expandable base material layer (Y1) The thickness ratio [(Y1) / (X1)] is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 1.0 or more, and still more preferably 5.0 or more. Also, it is preferably 1000 or less, more preferably 200 or less, still more preferably 60 or less, and still more preferably 30 or less.

Moreover, in the adhesive sheet used by 1 aspect of this invention, the thickness of the 2nd adhesive layer (X2) directly laminated | stacked with a non-expandable base material layer (Y2) and the said non-expandable base material layer (Y2). The ratio [(Y2) / (X2)] is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and preferably 20 or less, more preferably 10 or less. More preferably, it is 5 or less.

Hereinafter, the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2) constituting the substrate (Y) will be described.

<Expandable base material layer (Y1)>
The expandable substrate layer (Y1) constituting the substrate (Y) is a layer that contains expandable particles and can be expanded by a predetermined expansion treatment.
The content of expandable particles in the expandable substrate layer (Y1) is preferably 1 to 40% by mass, more preferably 5%, based on the total mass (100% by mass) of the expandable substrate layer (Y1). It is ˜35% by mass, more preferably 10 to 30% by mass, and still more preferably 15 to 25% by mass.

In addition, from the viewpoint of improving interlayer adhesion between the expandable base material layer (Y1) and other layers to be laminated, the surface of the expandable base material layer (Y1) is a surface formed by an oxidation method, a roughening method, or the like. Treatment, easy adhesion treatment, or primer treatment may be performed.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, and ultraviolet irradiation treatment. Examples of the unevenness method include sand blast method and solvent treatment method. Etc.

The expandable particles contained in the expandable substrate layer (Y1) may be any particles that expand by performing a predetermined treatment, such as thermally expandable particles that expand by heating at a predetermined temperature or higher, Examples include UV-expandable particles that absorb a predetermined amount of ultraviolet rays to generate gas and expand inside the particles.

The volume expansion coefficient of the expandable particles is preferably 1.5 to 100 times, more preferably 2 to 80 times, still more preferably 2.5 to 60 times, and still more preferably 3 to 40 times.

The average particle diameter of the 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, and still more preferably 10 to 50 μm.
The average particle size of the expandable particles is a volume-median particle size (D ₅₀ ), and is measured using a laser diffraction particle size distribution measuring device (for example, product name “Mastersizer 3000” manufactured by Malvern). In the particle distribution of the expandable particles, it means a particle size corresponding to 50% of the cumulative volume frequency calculated from the smaller particle size of the expandable particles.

The 90% particle diameter (D ₉₀ ) of the expandable particles before expansion at 23 ° C. is preferably 10 to 150 μm, more preferably 20 to 100 μm, still more preferably 25 to 90 μm, and still more preferably 30 to 80 μm. .
The 90% particle size (D ₉₀ ) of the expandable particles is the particle distribution of the expandable particles measured using a laser diffraction particle size distribution measuring device (for example, product name “Mastersizer 3000” manufactured by Malvern). In FIG. 5, the particle size corresponding to 90% of the cumulative volume frequency calculated from the smaller particle size of the expandable particles.

In one embodiment of the present invention, the expandable particles are preferably thermally expandable particles having an expansion start temperature (t) of 60 to 270 ° C.
That is, the expandable substrate layer (Y1) is preferably a thermally expandable substrate layer (Y1-1) containing thermally expandable particles having an expansion start temperature (t) of 60 to 270 ° C. The conductive base material layer (Y1-1) more preferably satisfies the following requirement (1).
Requirement (1): The storage elastic modulus E ′ (t) of the thermally expandable substrate layer (Y1-1) at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa It is as follows.
In the present specification, the storage elastic modulus E ′ of the thermally expandable base material layer (Y1-1) at a predetermined temperature means a value measured by the method described in the examples.

The requirement (1) can be said to be an index indicating the rigidity of the thermally expandable base material layer (Y1-1) immediately before the thermally expandable particles expand.
That is, when the thermally expandable particles expand, if the thermally expandable substrate layer (Y1-1) is flexible enough to satisfy the above requirement (1), the thermally expandable substrate layer (Y1 As a result, unevenness is likely to be formed on the surface of -1), and unevenness is also likely to occur on the adhesive surface of the first pressure-sensitive adhesive layer (X1). As a result, it is possible to easily separate them with a slight force at the interface P between the hard support and the first pressure-sensitive adhesive layer (X1).

From the above viewpoint, the storage elastic modulus E ′ (t) defined by requirement (1) of the thermally expandable base material layer (Y1-1) is preferably 9.0 × 10 ⁶ Pa or less, more preferably 8.0. × 10 ⁶ Pa or less, more preferably 6.0 × 10 ⁶ Pa or less, and still more preferably 4.0 × 10 ⁶ Pa or less.
In addition, the flow of the expanded heat-expandable particles is suppressed, the shape maintaining property of the unevenness generated on the surface of the heat-expandable base material layer (Y1-1) is improved, and the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) is improved. From the viewpoint of facilitating the formation of irregularities, the storage elastic modulus E ′ (t) defined by the requirement (1) of the thermally expandable base material layer (Y1-1) is preferably 1.0 × 10 ³ Pa or more. Preferably it is 1.0 × 10 ⁴ Pa or more, more preferably 1.0 × 10 ⁵ Pa or more.

The thermally expandable base material layer (Y1-1) preferably satisfies the following requirement (2), and more preferably satisfies the requirement (2) together with the requirement (1).
Requirement (2): The storage elastic modulus E ′ (23) of the thermally expandable base material layer (Y1-1) at 23 ° C. is 1.0 × 10 ⁶ Pa or more.

By using the thermally expansible base material layer (Y1-1) that satisfies the above requirement (2), it is possible to prevent misalignment when the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2). Moreover, excessive sinking of the semiconductor wafer into the second pressure-sensitive adhesive layer (X2) can also be prevented.

From the above viewpoint, the storage elastic modulus E ′ (23) of the thermally expandable base material layer (Y1-1) defined by the above requirement (2) is preferably 5.0 × 10 ⁶ to 5.0 × 10 ¹² Pa. More preferably 1.0 × 10 ⁷ to 1.0 × 10 ¹² Pa, still more preferably 5.0 × 10 ⁷ to 1.0 × 10 ¹¹ Pa, and still more preferably 1.0 × 10 ⁸ to 1. 0 × 10 ¹⁰ Pa.

The heat-expandable particles contained in the heat-expandable base material layer (Y1-1) are preferably heat-expandable particles having an expansion start temperature (t) of 60 to 270 ° C.
In the present specification, the expansion start temperature (t) of the thermally expandable particles means a value measured based on the following method.
[Measurement method of expansion start temperature (t) of thermally expandable particles]
To an aluminum cup having a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, 0.5 mg of thermally expandable particles to be measured is added, and an aluminum lid (diameter 5.6 mm, thickness 0. 1 mm) is prepared.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured from the upper part of the aluminum lid to the sample with a force of 0.01 N applied by a pressurizer. Then, in a state where a force of 0.01 N is applied by the pressurizer, heating is performed from 20 ° C. to 300 ° C. at a rate of temperature increase of 10 ° C./min, and the amount of displacement of the pressurizer in the vertical direction is measured. Let the displacement start temperature be the expansion start temperature (t).

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

Examples of the inclusion component contained in the outer shell include propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane, cyclobutane, cyclopentane. , Cyclohexane, cycloheptane, cyclooctane, neopentane, dodecane, isododecane, cyclotridecane, hexylcyclohexane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, iso Hexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, , 6,10,14-tetramethylpentadecane, cyclotridecane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane, etc. .
These encapsulated components may be used alone or in combination of two or more.
The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of inclusion component.

The expandable substrate layer (Y1) is preferably formed from a resin composition (y) containing a resin and expandable particles.
In addition, you may contain the additive for base materials in the resin composition (y) in the range which does not impair the effect of this invention as needed.
Examples of the substrate additive include an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and a colorant.
These base material additives may be used alone or in combination of two or more.
When these base material additives are contained, the content of each base material additive is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to about 100 parts by mass of the resin. 10 parts by mass.

The expandable particles contained in the resin composition (y), which is a material for forming the expandable substrate layer (Y1), are as described above, and are preferably thermally expandable particles.
The content of the expandable particles is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, and further preferably 10 to 10% by mass with respect to the total amount (100% by mass) of the active ingredients of the resin composition (y). 30% by mass, and still more preferably 15 to 25% by mass.

The resin contained in the resin composition (y) that is a material for forming the expandable base material layer (Y1) may be a non-adhesive resin or an adhesive resin.
That is, even if the resin contained in the resin composition (y) is an adhesive resin, the adhesive resin is a polymerizable compound in the process of forming the expandable base material layer (Y1) from the resin composition (y). And the resulting resin becomes a non-adhesive resin, and the expandable base material layer (Y1) containing the resin may be non-adhesive.

The mass average molecular weight (Mw) of the resin contained in the resin composition (y) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and still more preferably 1,000 to 500,000.
Further, when the resin is a copolymer having two or more kinds of structural units, the form of the copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer It may be.

The content of the resin is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and still more preferably 65 to 90% by mass with respect to the total amount (100% by mass) of the active ingredients of the resin composition (y). %, More preferably 70 to 85% by mass.

In one aspect of the present invention, the resin contained in the resin composition (y) is an acrylic urethane from the viewpoint of forming an expandable base layer (Y1) that easily forms irregularities on the surface when the expandable particles are expanded. It is preferable that 1 or more types chosen from a system resin and an olefin resin are included.
Moreover, as said acrylic urethane type 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.

[Acrylic urethane resin (U1)]
Examples of the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) include a reaction product of a polyol and a polyvalent isocyanate.
The urethane prepolymer (UP) is preferably obtained by further subjecting it to a chain extension reaction using a chain extender.

Examples of the polyol used as a raw material for the urethane prepolymer (UP) include alkylene type polyols, ether type polyols, ester type polyols, ester amide type polyols, ester / ether type polyols, and carbonate type polyols.
These polyols may be used independently and may use 2 or more types together.
The polyol used in one embodiment of the present invention is preferably a diol, more preferably an ester diol, an alkylene diol, and a carbonate diol, and even more preferably an ester diol and a carbonate diol.

Examples of the ester diol include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol; ethylene glycol, propylene glycol, One or more selected from diols such as alkylene glycols such as diethylene glycol and dipropylene glycol; phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4 , 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 Hydrophthalic acid, Examples thereof include condensation polymers of one or more selected from dicarboxylic acids such as hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid, and anhydrides thereof.
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 and polyneo Examples include pentyl terephthalate diol.

Examples of the alkylene type diol include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol; ethylene glycol, propylene glycol, And alkylene glycols such as diethylene glycol and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; polyoxyalkylene glycols such as polytetramethylene glycol; and the like.

Examples of the carbonate type diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, and 1,3-propylene carbonate diol. 2,2-dimethylpropylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, 1,4-cyclohexane carbonate diol, and the like.

Examples of the polyvalent isocyanate used as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
These polyvalent isocyanates may be used alone or in combination of two or more.
These polyisocyanates may be a trimethylolpropane adduct type modified product, a burette type modified product reacted with water, or an isocyanurate type modified product containing an isocyanurate ring.

Among these, as the polyvalent isocyanate used in one embodiment of the present invention, diisocyanate is preferable, and 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6 More preferred is at least one selected from tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanate.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-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-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, and isophorone diisocyanate (IPDI) is preferred.

In one embodiment of the present invention, the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is a reaction product of a diol and a diisocyanate, and is a straight chain having ethylenically unsaturated groups at both ends. A urethane prepolymer is preferred.
As a method for introducing an ethylenically unsaturated group into both ends of the linear urethane prepolymer, an NCO group at the end 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 include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy Examples thereof include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

As a vinyl compound used as the side chain of acrylic urethane resin (U1), at least (meth) acrylic acid ester is included.
The (meth) acrylic acid ester is preferably one or more selected from alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates, and more preferably used in combination with alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates.

When alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate are used in combination, the proportion of hydroxyalkyl (meth) acrylate to 100 parts by mass of alkyl (meth) acrylate is preferably 0.1 to 100 parts by mass, The amount is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 20 parts by mass, and still more preferably 1.5 to 10 parts by mass.

The carbon number of the alkyl group of the alkyl (meth) acrylate is preferably 1 to 24, more preferably 1 to 12, still more preferably 1 to 8, and still more preferably 1 to 3.

Moreover, as hydroxyalkyl (meth) acrylate, the same thing as the hydroxyalkyl (meth) acrylate used in order to introduce | transduce an ethylenically unsaturated group into the both ends of the above-mentioned linear urethane prepolymer is mentioned.

Examples of vinyl compounds other than (meth) acrylic acid esters include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, and vinyl toluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. Polar group-containing monomers such as (meth) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, and meta (acrylamide).
These may be used alone or in combination of two or more.

The content of the (meth) acrylic acid ester in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, and still more preferably based on the total amount (100% by mass) of the vinyl compound. It is 80 to 100% by mass, more preferably 90 to 100% by mass.

The total content of alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass with respect to the total amount (100% by mass) of the vinyl compound. The amount is 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass.

In the acrylic urethane resin (U1) used in one embodiment of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer (UP) and the structural unit (u12) derived from the vinyl compound [(u11 ) / (U12)] is preferably 10/90 to 80/20, more preferably 20/80 to 70/30, still more preferably 30/70 to 60/40, and still more preferably 35 by mass ratio. / 65 to 55/45.

[Olefin resin]
Examples of the olefin resin suitable as the resin contained in the resin composition (y) include a polymer having at least a structural unit derived from an olefin monomer.
The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specifically includes ethylene, propylene, butylene, isobutylene, 1-hexene and the like.
Among these, ethylene and propylene are preferable.

Specific olefinic resins, for example, ultra low density polyethylene (VLDPE, density: 880 kg / ^{m 3} or more 910 kg / ^m less than ^3), low density polyethylene (LDPE, density: 910 kg / ^{m 3} or more 915 kg / ^m less than ³ ), Medium density polyethylene (MDPE, density: 915 kg / m ³ or more and less than 942 kg / m ³ ), high density polyethylene (HDPE, density: 942 kg / m ³ or more), linear low density polyethylene, etc .; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefin elastomer (TPO); ethylene-vinyl acetate copolymer (EVA); ethylene-propylene- (5-ethylidene-2-norbornene), etc. Olefin terpolymers; and the like.

In one embodiment of the present invention, the olefin resin may be a modified olefin resin further modified by one or more selected from acid modification, hydroxyl group modification, and acrylic modification.

For example, as an acid-modified olefin resin obtained by subjecting an olefin resin to acid modification, a modified polymer obtained by graft polymerization of the above-mentioned unmodified olefin resin with an unsaturated carboxylic acid or its anhydride. Is mentioned.
Examples of the unsaturated carboxylic acid or anhydride thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth) acrylic acid, maleic anhydride, 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 independently and may use 2 or more types together.

An acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification is a modification obtained by graft polymerization of an alkyl (meth) acrylate as a side chain to the above-mentioned unmodified olefin resin as a main chain. A polymer is mentioned.
The number of carbon atoms of the alkyl group contained in the alkyl (meth) acrylate is preferably 1-20, more preferably 1-16, and still more preferably 1-12.
As said alkyl (meth) acrylate, the same thing as the compound which can be selected as a below-mentioned monomer (a1 ') is mentioned, for example.

Examples of the hydroxyl group-modified olefin resin obtained by modifying the olefin resin with a hydroxyl group include a modified polymer obtained by graft-polymerizing a hydroxyl group-containing compound to the above-mentioned unmodified olefin resin as the main chain.
Examples of the hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl. Examples thereof include hydroxyalkyl (meth) acrylates such as (meth) acrylate and 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol.

(Resin other than acrylic urethane resin and olefin resin)
In one embodiment of the present invention, the resin composition (y) may contain a resin other than the acrylic urethane-based resin and the olefin-based resin as long as the effects of the present invention are not impaired.
Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. Polyester resin such as phthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resin; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; Sulfides; Polyimide resins such as polyetherimide and polyimide; Polyamide resins; Acrylic resins; Fluorine resins and the like.

However, from the viewpoint of making the expandable base material layer (Y1) in which irregularities are easily formed on the surface when the expandable particles are expanded, the resin composition (y) contains a resin other than the acrylic urethane-based resin and the olefin-based resin. A smaller ratio is preferable.
The content ratio of the resin other than the acrylic urethane-based resin and the olefin-based 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 amount of the resin contained in the resin composition (y). Less than, more preferably less than 10 parts by weight, still more preferably less than 5 parts by weight, and even more preferably less than 1 part by weight.

[Solvent-free resin composition (y1)]
As one aspect of the resin composition (y), an oligomer having an ethylenically unsaturated group having a mass average molecular weight (Mw) of 50000 or less, an energy ray polymerizable monomer, and the above-described thermally expandable particles are blended, Examples thereof include a solventless resin composition (y1) that does not contain a solvent.
In the solventless resin composition (y1), no solvent is blended, but the energy beam polymerizable monomer contributes to the improvement of the plasticity of the oligomer.
By irradiating the coating film formed from the solventless resin composition (y1) with energy rays, an inflatable substrate layer (Y1) that easily forms irregularities on the surface when the expandable particles expand is formed. In particular, it is easy to form the heat-expandable base material layer (Y1-1) that satisfies the above requirements (1) and (2).

In addition, the type, shape, and blending amount (content) of the expandable particles blended in the solventless resin composition (y1) are the same as those of the resin composition (y) and are as described above.

The mass average molecular weight (Mw) of the oligomer contained in the solventless resin composition (y1) is 50000 or less, preferably 1000 to 50000, more preferably 2000 to 40000, and still more preferably 3000 to 35000. More preferably, it is 4000-30000.

Moreover, as said oligomer, what is necessary is just to have an ethylenically unsaturated group whose mass mean molecular weight is 50000 or less among resin contained in the above-mentioned resin composition (y), but the above-mentioned urethane prepolymer (UP ) Is preferred.
As the oligomer, a modified olefin resin having an ethylenically unsaturated group can also be used.

The total content of the oligomer and the energy beam polymerizable monomer in the solventless resin composition (y1) is preferably 50 to 100% with respect to the total amount (100% by mass) of the solventless resin composition (y1). It is 99% by mass, more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, and still more preferably 70 to 85% by mass.

Examples of the energy ray polymerizable monomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantane ( Alicyclic polymerizable compounds such as (meth) acrylate and tricyclodecane acrylate; Aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate and phenol ethylene oxide modified acrylate; Tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, N- And heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam.
These energy beam polymerizable monomers may be used independently and may use 2 or more types together.

The blending ratio of the oligomer and the energy beam polymerizable monomer (the oligomer / energy beam polymerizable monomer) is preferably 20/80 to 90/10, more preferably 30/70 to 85/15, still more preferably 35/65. ~ 80/20.

In one embodiment of the present invention, it is preferable that the solventless resin composition (y1) is further blended with a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with a relatively low energy beam.

Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyro Nitrile, dibenzyl, diacetyl, 8-chloranthraquinone and the like can be mentioned.
These photoinitiators may be used independently and may use 2 or more types together.

The blending amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass with respect to the total amount (100 parts by mass) of the oligomer and the energy ray polymerizable monomer. The amount is preferably 0.02 to 3 parts by mass.

<Non-expandable base material layer (Y2)>
Examples of the material for forming the non-expandable base material layer (Y2) constituting the base material (Y) include paper materials, resins, metals, and the like.
Examples of the paper material include thin paper, medium quality paper, high quality paper, impregnated paper, coated paper, art paper, sulfate paper, glassine paper, and the like.
Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyethylene terephthalate, poly Polyester resins such as butylene terephthalate and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resin such as polyurethane and acrylic-modified polyurethane; polymethylpentene; polysulfone; polyether ether ketone; Polyethersulfone; Polyphenylene sulfide; Polyimide resin such as polyetherimide and polyimide; Polyamide resin; Acrylic resin; Tsu Motokei resin, and the like.
Examples of the metal include aluminum, tin, chromium, and titanium.

These forming materials may be composed of one kind or in combination of two or more kinds.
As a non-intumescent substrate layer (Y2) using two or more kinds of forming materials in combination, a paper film is laminated with a thermoplastic resin such as polyethylene, or a metal film is formed on the surface of a resin film or sheet containing a resin. And the like.
As a method for forming the metal layer, for example, the above metal is deposited by a PVD method such as vacuum deposition, sputtering, or ion plating, or a metal foil made of the above metal is attached using a general adhesive. And the like.

From the viewpoint of improving interlayer adhesion between the non-expandable base layer (Y2) and other layers to be laminated, when the non-expandable base layer (Y2) contains a resin, the non-expandable base layer ( Similarly to the expandable base material layer (Y1) described above, the surface of Y2) may be subjected to a surface treatment such as an oxidation method or an unevenness method, an easy adhesion treatment, or a primer treatment.

Moreover, when the non-intumescent base material layer (Y2) contains a resin, it may contain the above-mentioned base material additive that can be contained in the resin composition (y) together with the resin.

The non-intumescent substrate layer (Y2) is present at a position farther from the first pressure-sensitive adhesive layer (X1) than the above-described inflatable substrate layer (Y1), and the inflatable substrate layer (Y1) ) And the first pressure-sensitive adhesive layer (X1), there is no non-expandable base layer (Y2), and the non-expandable base layer (Y2) when the expandable particles expand. The storage elastic modulus E ′ is preferably larger than the storage elastic modulus E ′ of the expandable base material layer (Y1) when the expandable particles expand. Thus, since there is no non-expandable base material layer (Y2) between the expandable base material layer (Y1) and the first pressure-sensitive adhesive layer (X1), the expandable base material layer is expanded by the expansion of the expandable particles. The unevenness generated on the surface of (Y1) is transmitted to the first pressure-sensitive adhesive layer (X1) without interposing the non-intumescent base material layer (Y2), and on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1). Also, unevenness is likely to occur. Further, when the expandable particles expand, the storage elastic modulus E ′ of the non-expandable base material layer (Y2) is larger than the storage elastic modulus E ′ of the expandable base material layer (Y1). During expansion, the surface of the expandable substrate layer (Y1) on the non-expandable substrate layer (Y2) side is prevented from being uneven, and as a result, the first of the expandable substrate layer (Y1). Unevenness is likely to occur on the surface on the pressure-sensitive adhesive layer (X1) side, and therefore unevenness is also likely to occur on the adhesive surface of the first pressure-sensitive adhesive layer (X1).
The storage elastic modulus E ′ of the non-expandable base material layer (Y2) when the expandable particles are expanded is as described above from the viewpoint of easily forming irregularities on the adhesive surface of the first adhesive layer (X1). Preferably, the pressure is 1.0 MPa or more. Also, from the viewpoint of ease of pasting and peeling operations, from the viewpoint of causing irregularities on the adhesive surface of the second pressure-sensitive adhesive layer (X2), or handling in a roll shape. From the viewpoint of easiness, it is preferably 1.0 × 10 ³ MPa or less. From this viewpoint, the storage elastic modulus E ′ of the non-expandable base material layer (Y2) when the expandable particles expand is preferably 1.0 to 5.0 × 10 ² MPa, more preferably 1.0. × 10 ¹ to 1.0 × 10 ² MPa, more preferably 5.0 × 10 ¹ to 1.0 × 10 ³ MPa.
In addition, from the viewpoints described above and from the viewpoint of preventing misalignment when the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2), the storage elastic modulus of the non-expandable base material layer (Y2) at 23 ° C. E ′ (23) is preferably 5.0 × 10 ¹ to 5.0 × 10 ⁴ MPa, more preferably 1.0 × 10 ² to 1.0 × 10 ⁴ MPa, and even more preferably 5.0 × 10. ² to 5.0 × 10 ³ MPa.
A non-expandable base material layer (Y2) is a non-expandable layer judged based on the above-mentioned method.
Therefore, the volume change rate (%) of the non-expandable base material layer (Y2) calculated from the above formula is less than 5% by volume, preferably less than 2% by volume, more preferably less than 1% by volume. More preferably, it is less than 0.1 volume%, More preferably, it is less than 0.01 volume%.

Moreover, as long as the volume change rate is the said range, a non-expandable base material layer (Y2) may contain a thermally expansible particle. For example, by selecting a resin contained in the non-expandable base material layer (Y2), it is possible to adjust the volume change rate to the above range even if thermally expandable particles are included.
However, the smaller the content of the heat-expandable particles in the non-expandable base material layer (Y2), the better.
The specific content of the heat-expandable particles is usually less than 3% by mass, preferably less than 1% by mass, and more preferably relative to the total mass (100% by mass) of the non-expandable base material layer (Y2). It is less than 0.1% by mass, more preferably less than 0.01% by mass, and still more preferably less than 0.001% by mass.

<First pressure-sensitive adhesive layer (X1), second pressure-sensitive adhesive layer (X2)>
The pressure-sensitive adhesive sheet used in one embodiment of the present invention has a first pressure-sensitive adhesive layer (X1) and a second pressure-sensitive adhesive layer (X2).
In the production method of the present invention, the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) is stuck to a hard support, and the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) is stuck to a semiconductor wafer.

The first pressure-sensitive adhesive layer (X1) has high adhesion to the hard support before the expansion of the expandable particles contained in the expandable base material layer (Y1), and the semiconductor wafer is sufficiently fixed to the hard support. The property which can do is required.
From this viewpoint, the storage shear modulus G ′ (23) of the first pressure-sensitive adhesive layer (X1) at 23 ° C. is preferably 1.0 × 10 ⁸ Pa or less, more preferably 5.0 × 10 ⁷ Pa or less. More preferably, it is 1.0 × 10 ⁷ Pa or less.

On the other hand, when the expandable particles in the expandable base material layer (Y1) expand, the unevenness generated on the surface of the expandable base material layer (Y1) is also applied to the adhesive surface of the first pressure-sensitive adhesive layer (X1). Rigidity that can be formed is also required.
From this viewpoint, the storage shear modulus G ′ (23) of the first pressure-sensitive adhesive layer (X1) at 23 ° C. is preferably 1.0 × 10 ⁴ Pa or more, more preferably 5.0 × 10 ⁴ Pa or more. More preferably, it is 1.0 × 10 ⁵ Pa or more.

The second pressure-sensitive adhesive layer (X2) is required not only to adhere to the semiconductor wafer but also to adhere to the semiconductor chip obtained by dividing the semiconductor wafer, and the semiconductor chip It is also necessary to suppress the phenomenon of excessive sinking into the agent layer (X2).
From these viewpoints, the storage shear modulus G ′ (23) of the second pressure-sensitive adhesive layer (X2) at 23 ° C. is preferably 1.0 × 10 ⁴ to 1.0 × 10 ⁸ Pa, more preferably 5 0.0 × 10 ⁴ to 5.0 × 10 ⁷ Pa, more preferably 1.0 × 10 ⁵ to 1.0 × 10 ⁷ Pa.
In addition, in this specification, the storage shear elastic modulus G '(23) of the 1st adhesive layer (X1) and the 2nd adhesive layer (X2) means the value measured by the method as described in an Example. .

The thickness of the first pressure-sensitive adhesive layer (X1) is preferably 1 to 60 μm, more preferably 2 to 50 μm, still more preferably 3 to 40 μm, and still more preferably 5 to 30 μm.

The thickness of the second pressure-sensitive adhesive layer (X2) is preferably 1 to 60 μm, more preferably 2 to 50 μm, still more preferably 3 to 40 μm, and still more preferably 5 to 30 μm.

The first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) can be formed from a pressure-sensitive adhesive composition (x) containing a pressure-sensitive adhesive resin.
Moreover, adhesive composition (x) may contain additives for adhesives, such as a crosslinking agent, a tackifier, a polymeric compound, a polymerization initiator, as needed.
Hereinafter, each component contained in the pressure-sensitive adhesive composition (x) will be described.

(Adhesive resin)
As the adhesive resin used in one embodiment of the present invention, any polymer may be used as long as the resin has adhesiveness and has a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin used in one embodiment of the present invention is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000, from the viewpoint of improving the adhesive strength. ~ 1 million.

Specific examples of the adhesive resin include rubber resins such as acrylic resins, urethane resins, and 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.
Further, when these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer is not particularly limited, and a block copolymer, a random copolymer, and a graft copolymer are not limited. Any of polymers may be used.

The adhesive resin used in one embodiment of the present invention may be an energy ray curable adhesive resin in which a polymerizable functional group is introduced into the side chain of the above-mentioned adhesive resin.
For example, by forming the second pressure-sensitive adhesive layer (X2) from an energy ray-curable pressure-sensitive adhesive composition containing an energy ray-curable pressure-sensitive adhesive resin, the adhesive force can be reduced by irradiating energy rays. Therefore, the obtained semiconductor chip can be easily picked up from the second pressure-sensitive adhesive layer (X2).
Examples of the polymerizable functional group include a (meth) acryloyl group and a vinyl group.
Examples of energy rays include ultraviolet rays and electron beams, but ultraviolet rays are preferred.
In addition, as a forming material of the adhesive layer which can irradiate an energy ray and can reduce adhesive force, the energy ray hardening-type adhesive composition containing the monomer or oligomer which has a polymerizable functional group may be sufficient.

These energy ray curable pressure-sensitive adhesive compositions preferably further contain a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with a relatively low energy beam.
As a photoinitiator, the same thing as what is mix | blended with the above-mentioned solvent-free resin composition (y1) is mentioned.
The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 100 parts by mass of the energy ray curable adhesive resin or 100 parts by mass of the monomer or oligomer having a polymerizable functional group. The amount is 0.03 to 5 parts by mass, more preferably 0.05 to 2 parts by mass.

In one embodiment of the present invention, the adhesive resin preferably contains an acrylic resin from the viewpoint of developing an excellent adhesive force. In particular, by forming the first pressure-sensitive adhesive layer (X1) from a pressure-sensitive adhesive composition containing an acrylic resin, it is possible to easily form irregularities on the surface of the first pressure-sensitive adhesive layer.

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

The content of the adhesive resin is preferably 35 to 100% by mass, more preferably 50 to 100% by mass, still more preferably relative to the total amount (100% by mass) of the active ingredients of the adhesive composition (x). It is 60 to 98% by mass, more preferably 70 to 95% by mass.

(Crosslinking agent)
In one aspect of the present invention, when the pressure-sensitive adhesive composition (x) contains a pressure-sensitive adhesive resin having a functional group, the pressure-sensitive adhesive composition (x) preferably further contains a crosslinking agent.
The said crosslinking agent reacts with the adhesive resin which has a functional group, and bridge | crosslinks adhesive resins by using the said functional group as a crosslinking origin.

Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent.
These crosslinking agents may be used independently and may use 2 or more types together.
Among these crosslinking agents, an isocyanate-based crosslinking agent is preferable from the viewpoints of increasing cohesive force and improving adhesive force and availability.

The content of the crosslinking agent is appropriately adjusted depending on the number of functional groups that the adhesive resin has, but is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the adhesive resin having a functional group, The amount is more preferably 0.03 to 7 parts by mass, still more preferably 0.05 to 5 parts by mass.

(Tackifier)
In one embodiment of the present invention, the pressure-sensitive adhesive composition (x) may further contain a tackifier from the viewpoint of further improving the adhesive strength.
In the present specification, the “tackifier” is a component that assists in improving the adhesive strength of the above-mentioned adhesive resin, and refers to an oligomer having a mass average molecular weight (Mw) of less than 10,000. It is distinguished from a functional resin.
The mass average molecular weight (Mw) of the tackifier is preferably 400 to 10000, more preferably 500 to 8000, and still more preferably 800 to 5000.

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

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and still more preferably 70 to 150 ° C.
In the present specification, the “softening point” of the tackifier means a value measured according to JIS K2531.
A tackifier may be used independently and may use together 2 or more types from which a softening point and a structure differ.
And when using 2 or more types of several tackifier, it is preferable that the weighted average of the softening point of these several tackifier belongs to the said range.

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

(Adhesive additive)
In one embodiment of the present invention, the pressure-sensitive adhesive composition (x) contains an additive for pressure-sensitive adhesives used for general pressure-sensitive adhesives in addition to the above-mentioned additives, as long as the effects of the present invention are not impaired. You may do it.
Examples of such an adhesive additive include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, antistatic agents, and the like. Is mentioned.
These pressure-sensitive adhesive additives may be used alone or in combination of two or more.

When these pressure-sensitive adhesive additives are contained, the content of each pressure-sensitive adhesive additive is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 100 parts by mass of the adhesive resin. ~ 10 parts by mass.

In addition, it is preferable that a 1st adhesive layer (X1) and a 2nd adhesive layer (X2) are non-expandable adhesive layers. Therefore, the content of the expandable particles in the pressure-sensitive adhesive composition (x), which is a material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2), is preferably as small as possible.
As the content of the expandable particles, the total amount (100% by mass) of the active ingredient of the pressure-sensitive adhesive composition (x), or the total mass of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) ( 100% by mass), preferably less than 1% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and still more preferably less than 0.001% by mass.

<Release material>
In the pressure-sensitive adhesive sheet used in one embodiment of the present invention, a release material may be further laminated on the pressure-sensitive adhesive surfaces of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2).
As the release material, a release sheet that has been subjected to a double-sided release process, a release sheet that has been subjected to a single-sided release process, or the like is used. Examples include a release material coated on a release material substrate.

Examples of the base material for the release material include papers such as high-quality paper, glassine paper, and kraft paper; polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; and olefins such as polypropylene resin and polyethylene resin. A plastic film such as a resin film;

Examples of the release agent include silicone-based resins, olefin-based resins, isoprene-based resins, rubber-based elastomers such as butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, and still more preferably 35 to 80 μm.

[Each step of the semiconductor chip manufacturing method of the present invention]
The manufacturing method of the present invention is a method for manufacturing a semiconductor chip from a semiconductor wafer using the above-mentioned adhesive sheet, and includes the following steps (1) to (3).
Step (1): A step of sticking the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) to the hard support and sticking the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) to the surface of the semiconductor wafer.
Step (2): A step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The interface between the hard support and the first pressure-sensitive adhesive layer (X1) while the expandable particles are expanded and the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are adhered. Separating with P.

The semiconductor chip manufacturing method of the present invention can be applied to the so-called stealth dicing method, and can also be applied to the tip dicing method.

The production method of one embodiment of the present invention preferably further includes the following step (4), and more preferably includes the following steps (4) to (6).
Step (4): After separation from the hard support in Step (3), the back surface opposite to the circuit surface of the plurality of semiconductor chips is formed with a base film, an adhesive layer and / or an adhesive layer. A step of removing the pressure-sensitive adhesive sheet from the semiconductor chip after being attached to the transfer tape.
Step (5): a step of stretching the transfer tape in the MD direction to widen the interval between the plurality of semiconductor chips.
Step (6): A step of separating a plurality of semiconductor chips from the transfer tape to obtain a semiconductor chip.

FIG. 2 is a schematic cross-sectional view in steps (1) to (3) of the semiconductor chip manufacturing method of the present invention, and FIG. 3 is a schematic cross-sectional view in steps (4) to (6).
Hereinafter, steps (1) to (4) will be described with reference to FIGS. 2 and 3 as appropriate.

<Step (1)>
FIG. 2A is a schematic cross-sectional view in step (1) showing a state in which the semiconductor wafer 60 is stuck to the hard support 50 using the adhesive sheet 1a shown in FIG.
In step (1), the adhesive surface of the first adhesive layer (X1) of the adhesive sheet 1a is attached to the hard support 50, and the circuit of the semiconductor wafer 60 is formed on the adhesive surface of the second adhesive layer (X2). It is preferable to affix to the circuit surface 61 made.
In addition, in FIG. 2, although the aspect using the adhesive sheet 1a shown to Fig.1 (a) is shown, also when using the adhesive sheet which has another structure, a hard support body, an adhesive sheet, And the semiconductor wafer are laminated in this order, and the adhesive surface of the first adhesive layer (X1) of the adhesive sheet is adhered to the hard support and the adhesive surface of the second adhesive layer (X2) is adhered to the circuit surface of the semiconductor wafer. It is preferable.

The hard support is preferably attached to the entire pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet. Therefore, the hard support is preferably plate-shaped.
Moreover, it is preferable that the area of the surface of the hard support body affixed with the 1st adhesive layer (X1) is more than the area of the adhesive surface of a 1st adhesive layer (X1), as shown in FIG.

Examples of the material constituting the hard support include, for example, metal materials such as SUS; non-metallic inorganic materials such as glass and silicon wafers; epoxy resins, ABS resins, acrylic resins, engineering plastics, super engineering plastics, polyimide resins, polyamideimides Examples thereof include resin materials such as resins; composite materials such as glass epoxy resins, and among these, SUS, glass, and silicon wafers are preferable.
Examples of engineering plastics include nylon, polycarbonate (PC), and polyethylene terephthalate (PET).
Examples of super engineering plastics include polyphenylene sulfide (PPS), polyether sulfone (PES), and polyether ether ketone (PEEK).

The thickness of the hard support is preferably 20 μm or more and 50 mm or less, and more preferably 60 μm or more and 20 mm or less.

The Young's modulus of the hard support is preferably 1.0 GPa or more, more preferably 5.0 GPa or more, still more preferably 10 GPa or more, and still more preferably 20 GPa or more, from the viewpoint of improving chip crack prevention performance.
In the present specification, the Young's modulus of the hard support is a value measured at room temperature (25 ° C.) in accordance with the static Young's modulus test method of JIS Z2280: 1993.

The surface of the semiconductor wafer attached to the adhesive surface of the second adhesive layer (X2) is preferably a circuit surface on which a circuit is formed.
On the other hand, the surface of the semiconductor wafer opposite to the circuit surface (hereinafter also referred to as “back surface”) is ground in the next process to divide the semiconductor wafer into a plurality of semiconductor chips. Etc. are preferably flat surfaces which are not formed.
By sticking the adhesive surface of the second adhesive layer (X2) to the circuit surface of the semiconductor wafer, the circuit surface can be protected.

The semiconductor wafer used in the manufacturing method of the present invention is obtained by forming a circuit on one surface of a semiconductor wafer composed of silicon, SiC (silicon carbide), gallium, arsenic, or the like by an etching method, a lift-off method, or the like. Can do.

In the semiconductor wafer, a process for forming a modified region inside the semiconductor wafer for application to the stealth dicing method, or a groove in the thickness direction from the surface of the semiconductor wafer for application to the previous dicing method is formed. It is necessary to perform processing.
You may affix the circuit surface of the semiconductor wafer which performed these processes previously on the adhesion surface of a 2nd adhesive layer (X2). In addition, after the circuit surface of the semiconductor wafer that has not been subjected to these treatments is attached to the adhesive surface of the second pressure-sensitive adhesive layer (X2) in this step, these treatments may be performed from the back surface of the semiconductor wafer. .

In particular, the process of forming the modified region inside the semiconductor wafer for application to the stealth dicing method is performed after the circuit surface of the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2). preferable.
The semiconductor wafer is attached to the hard support via the adhesive sheet by applying the modified region forming process after the circuit surface of the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2). The warp of the semiconductor wafer that can occur after the modified region is formed can be effectively suppressed.

When manufacturing semiconductor chips by stealth dicing, the process for forming a modified region inside a semiconductor wafer is to use a laser with a laser beam incident oblique surface on the back side of the semiconductor wafer and a focusing point inside the workpiece. There is a method of forming a modified region by multiphoton absorption by irradiating light. When forming the modified region, a crack line extending from the modified region in the thickness direction of the semiconductor wafer is also formed.

On the other hand, the treatment for forming grooves in the thickness direction from the surface of the semiconductor wafer for application to the prior dicing method may be performed before or after the semiconductor wafer is bonded to the second pressure-sensitive adhesive layer (X2). May be.
In the case where a semiconductor chip is manufactured by the prior dicing method, a method of forming a groove in the thickness direction from the surface of the semiconductor wafer includes a method of performing dicing using a known wafer dicing apparatus or the like.

In addition, it is preferable to perform a process (1) in the environment where an expandable particle does not expand | swell.
For example, when thermally expandable particles are used as the expandable particles, the step (1) may be performed under a temperature condition that is lower than the expansion start temperature (t) of the thermally expandable particles. Is preferably performed in an environment of 0 to 80 ° C. (when the expansion start temperature (t) is 60 to 80 ° C., in an environment lower than the expansion start temperature (t)).

<Step (2)>
Step (2) is a step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
As a method for dividing the semiconductor wafer, a method of grinding the back surface of the semiconductor wafer and dividing the semiconductor wafer into a plurality of semiconductor chips is preferable.
FIG. 2B is a schematic cross-sectional view when the back surface 62 of the semiconductor wafer 60 is ground and separated into a plurality of semiconductor chips.

For example, in the stealth dicing method, in this step, a semiconductor wafer having a modified region is ground on a back surface on which a circuit opposite to the circuit surface is not formed, and the semiconductor wafer is divided into a plurality of semiconductor chips. It becomes the process of obtaining.
In the stealth dicing method, the modified region is an embrittled portion of the semiconductor wafer, so that the thickness of the semiconductor wafer is reduced by grinding the back surface of the semiconductor wafer, and the grinding force is applied to the semiconductor wafer. Is a region that becomes a starting point of being broken and separated into semiconductor chips. As a result, the semiconductor wafer is divided along the modified region and the crack line and separated into a plurality of semiconductor chips.

Also, in the tip dicing method, this step is performed by grinding a semiconductor wafer having a groove formed in the thickness direction in advance on a back surface on which a circuit opposite to the circuit surface is not formed, thereby dividing the semiconductor wafer. Thus, this is a step of obtaining a plurality of semiconductor chips.
In the prior dicing method, the groove formed in the semiconductor wafer is a groove having a depth shallower than the thickness of the semiconductor wafer. Here, in this step, the semiconductor wafer is ground and thinned to at least the position reaching the bottom of the groove, so that the groove becomes a notch penetrating the wafer, and the semiconductor wafer is divided into a plurality of semiconductor chips. It is separated.

As described above, in the manufacturing method of the present invention, the first pressure-sensitive adhesive layer (X1) to be attached to the hard support does not need to contain expandable particles, and thus the semiconductor wafer is sufficiently fixed to the hard support. Thus, back surface grinding for dividing the semiconductor wafer can be performed. As a result, adverse effects such as chipping of the end of the obtained semiconductor chip can be effectively suppressed, and the yield in manufacturing the semiconductor chip can be improved.

In addition, it is preferable to perform also in a process (2) in the environment where an expandable particle does not expand | swell.
For example, when thermally expandable particles are used as the expandable particles, the step (2) may be performed under a temperature condition that is lower than the expansion start temperature (t) of the thermally expandable particles. Is preferably performed in an environment of 0 to 80 ° C. (when the expansion start temperature (t) is 60 to 80 ° C., in an environment lower than the expansion start temperature (t)).

<Step (3)>
In the step (3), the expandable particles are expanded, and the interface between the hard support and the first pressure-sensitive adhesive layer (X1) while the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are adhered. This is a step of separating by P.
FIG. 2C shows a state where the expandable particles in the expandable base material layer (Y1) are expanded and separated at the interface P between the hard support 50 and the first pressure-sensitive adhesive layer (X1). .
As shown in FIG. 2 (c), in this step, when the expandable particles are expanded, the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are stuck on the interface P from the hard support 50. Although it isolate | separates, it is further preferable not to isolate | separate between the layers of each layer which comprises the said adhesive sheet.

In this step, the method for expanding the expandable particles is appropriately selected according to the type of the expandable particles.
For example, when heat-expandable particles are used as the expandable particles, heat treatment is performed at a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles to expand the heat-expandable particles.
At this time, the “temperature higher than the expansion start temperature (t)” is preferably “expansion start temperature (t) + 10 ° C.” or higher and “expansion start temperature (t) + 60 ° C.” or lower. It is more preferable that the temperature is not less than “temperature (t) + 15 ° C.” and not more than “expansion start temperature (t) + 40 ° C.”.

In the production method of the present invention, the first pressure-sensitive adhesive layer adhered to the hard support by the expansion of the expandable particles using the pressure-sensitive adhesive sheet having the expandable base material layer (Y1) containing the expandable particles. By forming irregularities on the adhesive surface of (X1), it is adjusted so that it can be separated at the interface P between the hard support and the first adhesive layer (X1).
Therefore, it is possible to suppress the contamination of the hard support such that a part of the first pressure-sensitive adhesive layer (X1) remains on the surface of the hard support after the separation, and the washing process of the hard support can be omitted. Can be improved.

<Process (4)>
In the step (4), after separating from the hard support in the step (3), the back surface opposite to the circuit surface of the plurality of semiconductor chips, the base film, the pressure-sensitive adhesive layer and / or the adhesive layer are provided. In this step, the adhesive sheet is removed from the semiconductor chip after being attached to the transfer tape.
FIG. 3A shows a state where the adhesive sheet 1 a is removed from the semiconductor chip 70 after the back surfaces 72 of the plurality of semiconductor chips 70 are attached to the transfer tape 80.

In this step, when the second pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet 1a is a layer formed from an energy ray-curable pressure-sensitive adhesive composition, the second pressure-sensitive adhesive layer is irradiated with energy rays. The adhesive strength of (X2) may be reduced and the adhesive sheet 1a may be removed.
In addition, it is preferable to irradiate the energy ray irradiated in order to reduce the adhesive force of a 2nd adhesive layer (X2) from the adhesive sheet side.
After removing the adhesive sheet 1 a, the circuit surfaces 71 of the plurality of semiconductor chips 70 are exposed, and the back surfaces 72 are affixed to the transfer tape 80.

The transfer tape 80 is designed to be stretched by stretching in the MD direction, and is an adhesive tape designed to widen the interval between the plurality of semiconductor chips 70.
The transfer tape used in one embodiment of the present invention has a base film and a pressure-sensitive adhesive layer and / or an adhesive layer. Specific configurations include, for example, the following (1) to (3) ).
(1) A transfer tape obtained by laminating a base film and an adhesive layer in this order.
(2) A transfer tape obtained by laminating a base film and an adhesive layer in this order.
(3) A transfer tape formed by laminating a base film, a pressure-sensitive adhesive layer, and an adhesive layer in this order.

In FIG. 3, the case where the transfer tape of the aspect of the above (1) is used is shown. In the adhesive layer 82 of the transfer tape 80 formed by laminating the base film 81 and the adhesive layer 82 in this order, The state which stuck the back surface 72 of the several semiconductor chip 70 is shown.

(Base film)
As the base film constituting the transfer tape, for example, polyvinyl chloride resin, polyester resin (polyethylene terephthalate, etc.), acrylic resin, polycarbonate resin, polyethylene resin, polypropylene resin, acrylonitrile / butadiene / styrene resin, polyimide resin, polyurethane resin And a resin film containing one or more kinds of resins selected from polystyrene resins and the like.
The base film constituting the transfer tape preferably contains a thermoplastic elastomer, a rubber-based material, etc., and more preferably contains a thermoplastic elastomer.
Examples of the thermoplastic elastomer include urethane elastomers, olefin elastomers, vinyl chloride elastomers, polyester elastomers, styrene elastomers, acrylic elastomers, and amide elastomers.

The base film may have a single layer configuration or a multilayer configuration in which two or more layers are laminated.
The base film may further contain various additives such as pigments, dyes, flame retardants, plasticizers, antistatic agents, lubricants, fillers and the like.
The thickness of the base film constituting the transfer tape is preferably 20 to 300 μm, more preferably 30 to 250 μm, still more preferably 40 to 200 μm.

(Adhesive layer)
The pressure-sensitive adhesive layer constituting the transfer tape is a layer formed from the pressure-sensitive adhesive composition (x) which is a material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2). However, the energy ray curable pressure-sensitive adhesive layer formed from the above-mentioned energy ray curable pressure-sensitive adhesive composition, which is suitable as a material for forming the second pressure-sensitive adhesive layer (X2), is preferable.

When the pressure-sensitive adhesive layer constituting the transfer tape is an energy ray curable pressure-sensitive adhesive layer, the workability of the pickup step in step (6) is improved.
However, when irradiating energy rays when removing the pressure sensitive adhesive sheet in step (4), the energy rays when removing the pressure sensitive adhesive sheet are such that the adhesive strength of the energy ray curable pressure sensitive adhesive layer of the transfer tape does not decrease. It is preferable to irradiate from the adhesive sheet side.

The thickness of the pressure-sensitive adhesive layer constituting the transfer tape is preferably 1 to 100 μm, more preferably 3 to 50 μm, still more preferably 5 to 40 μm.

(Adhesive layer)
The adhesive layer constituting the transfer tape is preferably a layer formed from an adhesive composition containing a binder resin and a thermosetting component.
Examples of the binder resin include acrylic resins, polyester resins, urethane resins, acrylic urethane resins, silicone resins, rubber polymers, phenoxy resins, and the like, and acrylic resins are preferable.
As the thermosetting component, an epoxy resin and a thermosetting agent are preferably included.

The thickness of the adhesive layer constituting the transfer tape is preferably 1 to 100 μm, more preferably 5 to 75 μm, still more preferably 5 to 50 μm.

<Step (5)>
Step (5) is a step of extending the transfer tape in the MD direction and widening the interval between the plurality of semiconductor chips.
As shown in FIG. 3B, the transfer tape 80 is stretched in the MD direction to widen the interval between the plurality of semiconductor chips 70, so that the pickup property in the next process is improved.

<Step (6)>
Step (6) is a step of obtaining a semiconductor chip by separating a plurality of semiconductor chips from the transfer tape.
FIG. 3C shows a state in which a plurality of semiconductor chips 70 are obtained by picking up in this step using the transfer tape of the aspect (1).
Here, when the transfer tape used has an energy ray-curable pressure-sensitive adhesive layer, the adhesive force is reduced by irradiating the energy ray, and the pickup property can be improved.
In this case, it is preferable to irradiate the energy rays from the base film side.

When the transfer tape according to the above aspects (2) and (3) is used as the transfer tape, the adhesive layer remains firmly adhered to the back surface of the semiconductor chip at the time of picking up in this step, and the semiconductor chip with the adhesive layer is removed. And the bonding process can be omitted.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. In addition, the physical-property value in the following manufacture examples and Examples is a value measured by the following method.

<Mass average molecular weight (Mw)>
Using a gel permeation chromatograph (product name “HLC-8020” manufactured by Tosoh Corporation), the measurement was performed under the following conditions, and the value measured in terms of standard polystyrene was used.
(Measurement condition)
Column: "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", and "TSK gel G1000HXL" (both manufactured by Tosoh Corporation) Column temperature: 40 ° C
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min

<Measurement of thickness of each layer>
It was measured using a constant pressure thickness measuring instrument (model number: “PG-02J”, standard: conforming to JIS K6783, Z1702, Z1709) manufactured by Teclock Co., Ltd.

<Storage elastic modulus E ′ of thermally expandable base material layer (Y1)>
The formed heat-expandable base material layer (Y1) was 5 mm long × 30 mm wide × 200 μm thick, and the test piece was prepared by removing the release material.
Using a dynamic viscoelasticity measuring device (TA Instruments, product name “DMAQ800”), test start temperature 0 ° C., test end temperature 300 ° C., temperature increase rate 3 ° C./min, frequency 1 Hz, amplitude 20 μm Under the conditions, the storage elastic modulus E ′ of the test sample at a predetermined temperature was measured.

<Storage shear modulus G ′ of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2)>
A sample prepared by cutting the formed first pressure-sensitive adhesive layer (X1) and second pressure-sensitive adhesive layer (X2) into a circle having a diameter of 8 mm, removing the release material, and superposing them to obtain a thickness of 3 mm It was.
Using a viscoelasticity measuring device (manufactured by Anton Paar, device name “MCR300”), a torsional shear method under conditions of a test start temperature of 0 ° C., a test end temperature of 300 ° C., a heating rate of 3 ° C./min, and a frequency of 1 Hz Was used to measure the storage shear modulus G ′ of the test sample at a given temperature.

<Probe tack value>
A base material layer to be measured was cut into a square with a side of 10 mm, and then allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity) was used as a test sample.
Using a tacking tester (manufactured by Nippon Special Instrument Co., Ltd., product name “NTS-4800”) in an environment of 23 ° C. and 50% RH (relative humidity), the probe tack value on the surface of the test sample was measured according to JIS. It measured based on Z0237: 1991.
Specifically, a stainless steel probe having a diameter of 5 mm is 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 is moved at a speed of 10 mm / sec. The force required to separate from the surface was measured, and the obtained value was used as the probe tack value of the test sample.

<Measurement of adhesive strength of second adhesive layer (X2)>
On the adhesive surface of the second adhesive layer (X2) formed on the release film, a 50 μm thick PET film (product name “Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.) is laminated, did.
Then, the release film was removed, and the exposed adhesive surface of the second adhesive layer (X2) was attached to a stainless steel plate (SUS304 360 polishing) as an adherend, and 23 ° C., 50% RH (relative humidity). ) Under the same environment, the adhesive strength at 23 ° C. was measured at a pulling rate of 300 mm / min by the 180 ° peeling method in accordance with JIS Z0237: 2000.

<Young's modulus of hard support>
The measurement was performed at room temperature (25 ° C.) in accordance with the static Young's modulus test method of JIS Z2280: 1993.

Production Example 1 (Synthesis of acrylic urethane resin)
(1) Synthesis of urethane prepolymer)
In a reaction vessel under a nitrogen atmosphere, with respect to 100 parts by mass (solid content ratio) of polycarbonate diol having a weight average molecular weight of 1,000, isophorone diisocyanate has an equivalent ratio of hydroxyl group of polycarbonate diol and isocyanate group of isophorone diisocyanate of 1. / 1, 160 parts by mass of toluene was further added, and the mixture was allowed to react at 80 ° C. for 6 hours or more while stirring under a nitrogen atmosphere until the isocyanate group concentration reached the theoretical amount.
Subsequently, a solution obtained by diluting 1.44 parts by mass (solid content ratio) of 2-hydroxyethyl methacrylate (2-HEMA) in 30 parts by mass of toluene is added, and further at 80 ° C. until the isocyanate groups at both ends disappear. The reaction was performed for 6 hours to obtain a urethane prepolymer having a mass average molecular weight of 29,000.

(2) Synthesis of acrylic urethane-based resin In a reaction vessel under a nitrogen atmosphere, 100 parts by mass of urethane prepolymer obtained in Production Example 1 (solid content ratio), 117 parts by mass of methyl methacrylate (MMA) (solid content ratio), 2-hydroxyethyl methacrylate (2-HEMA) 5.1 parts by mass (solid content ratio), 1-thioglycerol 1.1 parts by mass (solid content ratio) and toluene 50 parts by mass were added and stirred at 105 ° C. The temperature was raised to.
Further, a solution obtained by further diluting 2.2 parts by mass (solid content ratio) of radical initiator (manufactured by Nippon Finechem Co., Ltd., product name “ABN-E”) with 210 parts by mass of toluene in a reaction vessel was heated to 105 ° C. It was dripped over 4 hours, maintaining.
After completion of dropping, the reaction was carried out at 105 ° C. for 6 hours to obtain an acrylic urethane resin solution having a mass average molecular weight of 105,000.

Production Example 2 (Preparation of adhesive sheet)
Details of the adhesive resin, additives, thermally expandable particles, base material, and release material used in the formation of each layer in the production of the following adhesive sheet are as follows.
<Adhesive resin>
Acrylic copolymer (i): having a structural unit derived from a raw material monomer consisting of 2-ethylhexyl acrylate (2EHA) / 2-hydroxyethyl acrylate (HEA) = 80.0 / 20.0 (mass ratio), An acrylic copolymer having a Mw of 600,000.
Acrylic copolymer (ii): n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) / acrylic acid = 86.0 / 8.0 / 5.0 / 1. An acrylic copolymer having an Mw of 600,000 having a structural unit derived from a raw material monomer consisting of 0 (mass ratio).
<Additives>
Isocyanate crosslinking agent (i): manufactured by Tosoh Corporation, product name “Coronate L”, solid content concentration: 75 mass%.
<Thermal expandable particles>
Thermally expandable particles (i): manufactured by Kureha Co., Ltd., product name “S2640”, expansion start temperature (t) = 208 ° C., average particle size (D ₅₀ ) = 24 μm, 90% particle size (D ₉₀ ) = 49 μm .
<Release material>
Heavy release film: manufactured by Lintec Corporation, product name “SP-PET382150”, a polyethylene terephthalate (PET) film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.
Light release film: manufactured by Lintec Co., Ltd., product name “SP-PET381031”, a PET film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.

(1) Formation of 1st adhesive layer (X1) To 100 mass parts of solid content of the said acrylic copolymer (i) which is adhesive resin, said isocyanate type crosslinking agent (i) 5.0 mass parts ( (Solid content ratio) was mixed, diluted with toluene, and stirred uniformly to prepare a pressure-sensitive adhesive composition having a solid content concentration (active ingredient concentration) of 25% by mass.
And the said adhesive composition is apply | coated to the surface of the release agent layer of the said heavy release film, a coating film is formed, the said coating film is dried at 100 degreeC for 60 second, and a non-expandable adhesive of thickness 5 micrometers. The 1st adhesive layer (X1) which is an agent layer was formed.
The storage shear modulus G ′ (23) of the first pressure-sensitive adhesive layer (X1) at 23 ° C. was 2.5 × 10 ⁵ Pa.

(2) Formation of 2nd adhesive layer (X2) To 100 mass parts of solid content of the said acrylic copolymer (ii) which is adhesive resin, 0.8 mass part of said isocyanate type crosslinking agent (i) ( (Solid content ratio) was mixed, diluted with toluene, and stirred uniformly to prepare an adhesive composition having a solid content concentration (active ingredient concentration) of 25 mass%.
And the said adhesive composition is apply | coated to the surface of the release agent layer of the said light release film, a coating film is formed, the said coating film is dried at 100 degreeC for 60 second, and 10 micrometers in thickness 2nd adhesive. Layer (X2) was formed.
The storage shear modulus G ′ (23) of the second pressure-sensitive adhesive layer (X2) at 23 ° C. was 9.0 × 10 ³ Pa.
Moreover, the adhesive force of the 2nd adhesive layer (X2) measured based on the said method was 1.0 N / 25mm.
Since it was clear that the second pressure-sensitive adhesive layer (X2) and the first pressure-sensitive adhesive layer (X1) had a probe tack value of 50 mN / 5 mmφ or more, measurement of the probe tack value was omitted.

(3) Production of substrate (Y) To 100 parts by mass of the solid content of the acrylic urethane-based resin obtained in Production Example 1, 6.3 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i), as a catalyst, Dioctyltin bis (2-ethylhexanoate) 1.4 parts by mass (solid content ratio) and the above-mentioned thermally expandable particles (i) were blended, diluted with toluene, stirred uniformly, and solid content concentration ( A resin composition having an active ingredient concentration of 30% by mass was prepared.
In addition, content of the thermally expansible particle (i) with respect to the whole quantity (100 mass%) of the active ingredient in the obtained resin composition was 20 mass%.
And on the surface of a 50 μm-thick polyethylene terephthalate (PET) film (product name “Cosmo Shine A4100”, probe tack value: 0 mN / 5 mmφ, which is a non-intumescent substrate) The product was applied to form a coating film, and the coating film was dried at 100 ° C. for 120 seconds to form an expandable substrate layer (Y1) having a thickness of 50 μm.
Here, the PET film corresponds to the non-expandable base material layer (Y2).

In addition, as a sample for measuring the physical property value of the expandable base material layer (Y1), the resin composition is applied to the surface of the release agent layer of the light release film to form a coating film, and the coating film is formed into 100. Drying was performed at ° C for 120 seconds to similarly form a 50 μm thick expandable base material layer (Y1).
And based on the above-mentioned measuring method, the storage elastic modulus and probe tack value in each temperature of an expansible base material layer (Y1) were measured. The measurement results were as follows.
-Storage elastic modulus E '(23) at 23 ° C. = 2.0 × 10 ⁸ Pa
-Storage elastic modulus E '(208) at 208 ° C = 5.0 x 10 ⁵ Pa
・ Probe tack value = 0mN / 5mmφ
Moreover, the storage elastic modulus and probe tack value at each temperature of the PET film, that is, the non-expandable base material layer (Y2) were measured. The measurement results were as follows.
-Storage elastic modulus E '(23) at 23 ° C. = 1.0 × 10 ³ MPa
-Storage elastic modulus E '(208) at 208 ° C = 0.8 x 10 ² MPa
・ Probe tack value = 0mN / 5mmφ

(4) Lamination of each layer The non-intumescent base material layer (Y2) of the base material (Y1) prepared in (1-3) above and the second pressure-sensitive adhesive layer (X2) formed in (2) above are attached. At the same time, the thermally expandable base material layer (Y1) and the first pressure-sensitive adhesive layer (X1) formed in the above (1) were bonded together.
And the heavy release film / first pressure-sensitive adhesive layer (X1) / expandable base material layer (Y1) / non-expandable base material layer (Y2) / second pressure-sensitive adhesive layer (X2) / light release film in this order A pressure-sensitive adhesive sheet was prepared by laminating.

As for the pressure-sensitive adhesive sheets prepared on the basis of the above-described method, peel force (F ₀₎ and (F ₁₎ measured in accordance with the following methods.
As a result, the peel force (F ₀ ) = 0.23 N / 25 mm and the peel force (F ₁ ) = 0 mN / 25 mm, and the ratio between the peel force (F ₁ ) and the peel force (F ₀ ) [(F ₁ ) / (F ₀ )] was 0.

<Measurement of peeling force (F ₀ )>
The prepared pressure-sensitive adhesive sheet was allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity), then the heavy release film of the pressure-sensitive adhesive sheet was removed, and the first pressure-sensitive adhesive layer (X1) exposed Was affixed to a silicon wafer.
Next, the end of the silicon wafer with the adhesive sheet attached is fixed to the lower chuck of the universal tensile testing machine (Orientec, product name “Tensilon UTM-4-100”), and the adhesive sheet is fixed with the upper chuck. did.
Then, in the same environment as above, peeling is performed at the interface P between the silicon wafer and the first pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet at a pulling speed of 300 mm / min according to JIS Z0237: 2000 by a 180 ° peeling method. The peeling force measured at the time of the measurement was defined as “peeling force (F ₀ )”.

<Measurement of peel force (F ₁ )>
Remove the heavy release film of the prepared pressure-sensitive adhesive sheet, stick the exposed first pressure-sensitive adhesive layer (X1) to a silicon wafer, heat at 240 ° C. for 3 minutes, and heat in the expandable base material layer (Y1) The expandable particles were expanded.
Thereafter, in the same manner as the measurement of the peel force (F ₀ ) described above, the peel force measured when peeled at the interface P between the silicon wafer and the first pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet under the above conditions. Was defined as “peeling force (F ₁ )”.
When measuring the peel force (F ₁ ), the adhesive sheet (I) is completely separated from the silicon wafer when the adhesive sheet is fixed with the upper chuck of the universal tensile testing machine and cannot be fixed. The measurement was terminated, and the peeling force (F ₁ ) at that time was set to “0 mN / 25 mm”.

Production Example 3 (Production of transfer tape)
Acrylic copolymer obtained by reacting butyl acrylate / 2-hydroxyethyl acrylate = 85/15 (mass ratio), and 80 mol% of methacryloyloxyethyl isocyanate (MOI) based on 2-hydroxyethyl acrylate The energy ray-curable acrylic copolymer having a mass average molecular weight (Mw) of 600,000 obtained by reacting with was used as an adhesive resin.
With respect to 100 parts by mass of the solid content of the energy ray curable acrylic copolymer, 3 parts by mass of 1-hydroxycyclophenyl ketone (product name “Irgacure 184”, manufactured by BASF) as a photopolymerization initiator is crosslinked. 0.45 parts by mass of a tolylene diisocyanate crosslinking agent (product name “Coronate L”, manufactured by Tosoh Corporation), which is an agent, was mixed in a solvent to obtain an adhesive composition.
Next, the adhesive composition was applied to the release-treated surface of the light release film (i) to form a coating film, and the coating film was dried to form an adhesive layer having a thickness of 10 μm.
And the single side | surface of the polyester-type polyurethane-elastomer sheet | seat (The product name "Higres DUS202", thickness 50micrometer) made from a Seadam company) was bonded together to the surface which this adhesive layer exposed.
As described above, a transfer tape obtained by laminating the base film, the pressure-sensitive adhesive layer, and the light release film in this order was obtained.

Example 1
<Step (1)>
The pressure-sensitive adhesive sheet produced in Production Example 2 was cut into a square size of 230 mm × 230 mm.
Using a tape grinder for back grind (manufactured by Lintec Corporation, device name “RAD-3510F / 12”), the heavy release film of the cut adhesive sheet was peeled off, and the first adhesive layer (X1) exposed was exposed. The adhesive surface was attached to a hard support (material: silicon, thickness: 725 μm, Young's modulus: 30 GPa). Further, the light release film is also peeled off, and a semiconductor wafer having a circuit surface with a circuit formed on one surface on the adhesive surface of the exposed second pressure-sensitive adhesive layer (X2) (diameter 200 mm, thickness 725 μm) The circuit surface of the disk shape was attached.
Then, using a stealth laser irradiation device (manufactured by Tokyo Seimitsu Co., Ltd., device name “ML300PlusWH”), stealth laser irradiation is performed from the back surface opposite to the circuit surface of the semiconductor wafer, and a modified region is formed inside the semiconductor wafer. Formed.

<Step (2)>
Using a polish grinder (manufactured by Tokyo Seimitsu Co., Ltd., device name “PG3000RM”), the back surface of the semiconductor wafer where the circuit is not formed is ground while being exposed to ultrapure water, and the semiconductor wafer is divided. Chips were separated into individual semiconductor chips with a thickness of 20 μm.

<Step (3)>
The temperature in the system including the hard support, the pressure-sensitive adhesive sheet, and the plurality of semiconductor chips was set to 240 ° C. that is equal to or higher than the expansion start temperature (208 ° C.) of the thermally expandable particles (i), and heat treatment was performed for 3 minutes. .
After the heat treatment, it could be easily separated at the interface between the hard support and the first pressure-sensitive adhesive layer (X1). At this time, the plurality of semiconductor chips remained stuck to the second pressure-sensitive adhesive layer (X2), and separation between the layers constituting the pressure-sensitive adhesive sheet did not occur.
Moreover, it was not confirmed that a part of 1st adhesive layer (X1) remained on the surface of a hard support after isolation | separation from a hard support, and contamination was not seen. Therefore, it is considered that it is not necessary to perform a new cleaning process on the surface of the hard support.

<Process (4)>
The transfer tape obtained in Production Example 3 was cut into a square size of 210 mm × 210 mm. At this time, each side of the cut transfer tape was cut so as to be parallel or perpendicular to the MD direction of the base film (Y2).
Next, the light release film was peeled off from the transfer tape, and the surface of the exposed pressure-sensitive adhesive layer and the back surfaces of the plurality of semiconductor chips separated from the hard support in step (3) were attached.
At this time, a group of a plurality of semiconductor chips are attached so as to be positioned at the center of the transfer tape, and dicing lines when separated from the semiconductor wafer are parallel or perpendicular to each side of the transfer tape. It stuck so that it might become. And the group of several semiconductor chips was peeled from the adhesive surface of the 2nd adhesive layer (X2), and the adhesive sheet was removed.

<Step (5)>
The transfer tape on which a plurality of semiconductor chips were attached was installed in an expanding apparatus capable of biaxial stretching. The expanding device has an X-axis direction (positive direction is + X-axis direction, negative direction is -X-axis direction) and Y-axis direction (positive direction is + Y-axis direction and negative direction is -Y). And holding means for extending in each direction (that is, + X-axis direction, -X-axis direction, + Y-axis direction, and -Y-axis direction).
Here, the MD direction of the transfer tape is aligned with the X-axis or Y-axis direction, installed in the expanding device, and each side of the transfer tape is gripped by the holding means. The space between the plurality of semiconductor chips attached to the transfer tape was widened.
-Number of holding means: 5 per side-Stretching speed: 5 mm / sec
-Stretching distance: Each side was stretched by 60 mm.

<Step (6)>
Using a UV irradiation device (product name “RAD-2000” manufactured by Lintec Corporation), UV light is irradiated from the base film side of the transfer tape (light quantity: 500 mJ / cm ² , illuminance: 220 mW / cm ² , irradiation speed) : 15 mm / s) to reduce the adhesive strength of the adhesive layer of the transfer tape. And it picked up and obtained the semiconductor chip.
In addition, the thing in which the chip | tip of the edge part was seen among the several obtained semiconductor chips was not confirmed.

1a, 1b Pressure-sensitive adhesive sheet (X1) First pressure-sensitive adhesive layer (X2) Second pressure-sensitive adhesive layer (Y) Base material (Y1) Expandable base material layer (Y2) Non-expandable base material layer (Y2-1) First Non-expandable base layer (Y2-2) Second non-expandable base layer 50 Hard support 60 Semiconductor wafer 61 Circuit surface 62 Back surface 70 Semiconductor chip 71 Circuit surface 72 Back surface 80 Transfer tape 81 Base film 82 Adhesive layer

Claims

A substrate (Y) comprising at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2);
On both surfaces of the substrate (Y), each has a first pressure-sensitive adhesive layer (X1) and a second pressure-sensitive adhesive layer (X2),
A method for producing a semiconductor chip from a semiconductor wafer using a pressure-sensitive adhesive sheet, in which unevenness may occur on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) due to expansion of the expandable particles,
A method for producing a semiconductor chip, comprising the following steps (1) to (3).
Step (1): A step of sticking the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) to the hard support and sticking the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive layer (X2) to the surface of the semiconductor wafer.
Step (2): A step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The interface between the hard support and the first pressure-sensitive adhesive layer (X1) while the expandable particles are expanded and the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) are adhered. Separating with P.
The pressure-sensitive adhesive sheet has a first pressure-sensitive adhesive layer (X1) on the expandable substrate layer (Y1) side of the substrate (Y), and the non-expandable substrate layer ( The manufacturing method of the semiconductor chip of Claim 1 which has a said 2nd adhesive layer (X2) in the Y2) side.
The base material (Y) is a non-expandable base material layer (Y2) provided on the expandable base material layer (Y1) and the first adhesive layer (X1) side of the inflatable base material layer (Y1). -1) and a non-intumescent substrate layer (Y2-2) provided on the second adhesive layer (X2) side of the expandable substrate layer (Y1),
The storage elastic modulus E ′ of the non-expandable base layer (Y2-1) when the expandable particles expand is determined by the storage modulus E ′ of the non-expandable base layer (Y2-2) when the expandable particles expand. The method for manufacturing a semiconductor chip according to claim 1, wherein the method is lower than an elastic modulus E ′.
The non-expandable base layer (Y2) is present at a position farther from the first pressure-sensitive adhesive layer (X1) than the expandable base layer (Y1), and the inflatable base layer (Y1) ) And the first pressure-sensitive adhesive layer (X1), the non-expandable base material layer (Y2) does not exist,
The storage elastic modulus E ′ of the non-expandable base layer (Y2) when the expandable particles expand is the storage elastic modulus E of the expandable base layer (Y1) when the expandable particles expand. The manufacturing method of the semiconductor chip of Claim 1 or 2 larger than '.
5. The method of manufacturing a semiconductor chip according to claim 1, wherein when the expandable particles are expanded in the step (3), they are not separated between layers constituting the pressure-sensitive adhesive sheet.
The method for manufacturing a semiconductor chip according to any one of claims 1 to 5, further comprising the following step (4).
Step (4): After separation from the hard support in Step (3), the back surface opposite to the circuit surface of the plurality of semiconductor chips is formed with a base film, an adhesive layer and / or an adhesive layer. A step of removing the pressure-sensitive adhesive sheet from the semiconductor chip after being attached to the transfer tape.
The method for manufacturing a semiconductor chip according to any one of claims 1 to 6, wherein the expandable particles are thermally expandable particles having an expansion start temperature (t) of 60 to 270 ° C.
8. The semiconductor chip according to claim 7, wherein expansion of the thermally expandable particles is performed by a heat treatment between “expansion start temperature (t) + 10 ° C.” to “expansion start temperature (t) + 60 ° C.” of the thermally expandable particles. Manufacturing method.
The expandable substrate layer (Y1) is a thermally expandable substrate layer (Y1-1) containing the thermally expandable particles, and the storage elastic modulus E of the thermally expandable substrate layer (Y1-1) at 23 ° C. '(23) is the manufacturing method of the semiconductor chip of Claim 7 or 8 which is 1.0 * 10 < 6 > Pa or more.
The method for manufacturing a semiconductor chip according to any one of claims 1 to 9, wherein a volume change rate (%) of the non-expandable base material layer (Y2) is less than 2% by volume.
Step (2) is a step in which a semiconductor wafer having a modified region is ground on the back surface on which the circuit opposite to the circuit surface is not formed, and the semiconductor wafer is divided to obtain a plurality of semiconductor chips. The method for manufacturing a semiconductor chip according to any one of claims 1 to 10.