JP7241744B2 - Semiconductor chip manufacturing method - Google Patents

Description

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

2. Description of the Related Art In the process of manufacturing semiconductor chips, various processing is often performed while a semiconductor wafer is attached to a support using an adhesive sheet.
The pressure-sensitive adhesive sheet used in this case is required to have properties such as being able to sufficiently fix the semiconductor wafer during processing, and being able to be easily peeled off from the support after processing.
As a pressure-sensitive adhesive sheet that can meet such demands, a heat-releasable pressure-sensitive adhesive sheet having a heat-expandable pressure-sensitive adhesive layer containing heat-expandable particles is known.

For example, in Patent Document 1, a heat-expandable adhesive layer is formed by using a heat-releasable double-sided pressure-sensitive adhesive sheet having a heat-expandable adhesive layer containing heat-expandable microspheres on one side of a substrate and an adhesive layer on the other side. A method is disclosed in which an adherend such as a wafer is attached to a support, and an adherend such as a wafer is adhered to the other adhesive layer, and the adherend is processed.
According to Patent Document 1, by using the above-described heat-peelable double-sided pressure-sensitive adhesive sheet, the smoothness of the surface of the adherend can be maintained during processing of the adherend, and after processing, when peeling off the double-sided pressure-sensitive adhesive sheet, It is said that the stress can be reduced and the adherend can be easily peeled off without damaging the adherend.

Japanese Patent Application Laid-Open No. 2003-292916

In the method for processing an adherend described in Patent Document 1, the heat-expandable adhesive layer of the above-described double-sided pressure-sensitive adhesive sheet is attached to a support, and the adherend is attached to the other adhesive layer, and the adherend is is processed.
However, the heat-expandable adhesive layer of the double-sided pressure-sensitive adhesive sheet used in the processing method of Patent Document 1 contains heat-expandable microspheres. There is concern about a decrease in adhesive strength with
A decrease in the adhesive force to the support causes various problems due to insufficient fixation of the adherend to the support. For example, in a chip processing method such as the pre-dicing method or the stealth dicing method, in which the back surface of the wafer is ground and divided into chips, the resulting chips have adverse effects such as chipping at the edges because they are not sufficiently fixed to the support. can occur.

Further, in Patent Document 1, when the double-sided pressure-sensitive adhesive sheet is peeled off from the support, the heat-expandable microspheres are expanded by heat treatment to form irregularities on the surface of the heat-expandable pressure-sensitive adhesive layer. By reducing the contact area, the adhesive strength is lowered and the adhesive is peeled off.
However, when the double-sided pressure-sensitive adhesive sheet is peeled off from the support by the above-described peeling method, it may be difficult to peel the double-sided pressure-sensitive adhesive sheet because some adhesive force may remain. In addition, part of the heat-expandable pressure-sensitive adhesive layer may remain on the surface of the support after peeling, requiring a step of washing the support, which is a factor in lowering productivity.
In order to prevent contamination of the support, it is conceivable to select a low-adhesive resin as the adhesive resin constituting the thermally expandable adhesive layer. During processing of the adherend, a problem may arise that the adherend is not sufficiently fixed to the adherend.

Advantageous Effects of Invention The present invention suppresses the chipping of the end portion of a semiconductor chip to improve the yield, and at the time of separating the support and the attached adhesive sheet, it is possible to easily separate them all at once, and the support after separation can be easily obtained. It is an object of the present invention to provide a method for manufacturing a semiconductor chip that suppresses contamination of the substrate and omits the step of cleaning the substrate.

In the process of manufacturing semiconductor chips by cutting a semiconductor wafer, the present inventors applied first adhesives to both surfaces of a base material comprising at least an expandable base material layer containing expandable particles and a non-expandable base material layer. It has been found that the above problems can be solved by using a pressure-sensitive adhesive sheet having an agent layer and a second pressure-sensitive 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);
Having a first adhesive layer (X1) and a second adhesive layer (X2) on both sides of the substrate (Y),
A method for producing a semiconductor chip from a semiconductor wafer using an adhesive sheet in which unevenness may occur on the adhesive surface of the first adhesive layer (X1) due to expansion of the expandable particles,
A method for manufacturing a semiconductor chip, comprising the following steps (1) to (3).
Step (1): A step of attaching the adhesive surface of the first adhesive layer (X1) to a hard support and attaching the adhesive surface of the second adhesive layer (X2) to the surface of a 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 adhesive sheet has a first adhesive layer (X1) on the expandable substrate layer (Y1) side of the substrate (Y), and the non-expandable group of the substrate (Y) The method for manufacturing a semiconductor chip according to the above [1], wherein the second adhesive layer (X2) is provided on the material layer (Y2) side.
[3] The substrate (Y) comprises the expandable substrate layer (Y1) and a non-expandable substrate provided on the first adhesive layer (X1) side of the expandable substrate layer (Y1). It has a layer (Y2-1) and a non-expandable base layer (Y2-2) provided on the second adhesive layer (X2) side of the expandable base layer (Y1),
The storage elastic modulus E′ of the non-expanding base layer (Y2-1) when the expandable particles expand is the storage modulus E′ of the non-expanding base layer (Y2-2) when the expandable particles expand. The method for manufacturing a semiconductor chip according to the above [1], wherein the elastic modulus is lower than E'.
[4] The non-expanding base layer (Y2) is located farther from the first pressure-sensitive adhesive layer (X1) than the expandable base layer (Y1), and the expandable base material The non-expandable base layer (Y2) is not present between the layer (Y1) and the first adhesive layer (X1),
The storage elastic modulus E′ of the non-expanding base layer (Y2) when the expandable particles expand is equal to the storage elastic modulus E of the expandable base layer (Y1) when the expandable particles expand. ', the method for manufacturing a semiconductor chip according to the above [1] or [2].
[5] Manufacture of the semiconductor chip according to any one of [1] to [4] above, wherein in the step (3), when the expandable particles are expanded, the layers constituting the adhesive sheet are not separated from each other. Method.
[6] The method for manufacturing a semiconductor chip according to any one of [1] to [5] above, further comprising the following step (4).
- Step (4): After separation from the hard support in step (3), the back surface of the plurality of semiconductor chips on the side opposite to the circuit surface is covered with a base film and an adhesive layer and/or an adhesive layer. removing the adhesive sheet from the semiconductor chip after attaching it to the transfer tape provided;
[7] The method for producing a semiconductor chip according to any one of [1] to [6] above, wherein the expandable particles are thermally expandable particles having an expansion start temperature (t) of 60 to 270°C.
[8] In the above [7], wherein the thermally expandable particles are expanded by heat treatment between "expansion start temperature (t) + 10 ° C." and "expansion start temperature (t) + 60 ° C." A method of manufacturing the semiconductor chip described.
[9] The expandable substrate layer (Y1) is the thermally expandable substrate layer (Y1-1) containing the thermally expandable particles, and the thermally expandable substrate layer (Y1-1) is stored at 23°C. The method for manufacturing a semiconductor chip according to [7] or [8] above, wherein the elastic modulus E′(23) is 1.0×10 ⁶ Pa or more.
[10] The method for producing a semiconductor chip according to any one of [1] to [9] above, wherein the non-expandable base layer (Y2) has a volume change rate (%) of 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 is not formed, opposite to the circuit surface, 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] above, which is a step.

According to the method for manufacturing a semiconductor chip of the present invention, chipping or the like of the end portion of the semiconductor chip to be obtained is suppressed and the yield is improved. In addition to facilitating separation, contamination of the support after separation can be suppressed and a step of washing the support can be omitted, thereby improving productivity.

BRIEF DESCRIPTION OF THE DRAWINGS 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. 3A to 3C are schematic cross-sectional views in steps (1) to (3) of the method for manufacturing a semiconductor chip of the present invention; 4A to 4C are cross-sectional schematic diagrams in steps (4) to (6) of the method for manufacturing a semiconductor chip of the present invention;

In this specification, whether the target layer is an "intumescent layer" or a "non-intumescent layer" is determined by performing a treatment for swelling for 3 minutes, and then performing the following before and after the treatment. Judgment is made based on the volume change rate calculated from the formula.
・ Volume change rate (%) = {(volume of the layer after treatment - volume of the layer before treatment) / volume of the layer before treatment} x 100
In other words, if the volume resistivity is 5% by volume or more, the layer is determined to be an "intumescent layer", and if the volume change rate is less than 5% by volume, the layer is considered to be a "non-intumescent layer". We judge that it is.
As the "treatment for expansion", for example, when the expandable particles are thermally expandable particles, heat treatment may be performed for 3 minutes at the expansion start temperature (t) of the thermally expandable particles. .

As used herein, the term “active ingredient” refers to the components contained in the target composition, excluding the diluent solvent.
Further, the mass average molecular weight (Mw) is a value converted to standard polystyrene measured by gel permeation chromatography (GPC), specifically a value measured based on the method described in Examples.

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

[Method for producing a semiconductor chip of the present invention]
The method for manufacturing a semiconductor chip of the present invention (hereinafter also simply referred to as "the manufacturing method of the present invention") comprises at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2). A base material (Y) and a first pressure-sensitive adhesive layer (X1) and a second pressure-sensitive adhesive layer (X2) are provided on both sides of the base material (Y), respectively. This is a method for producing semiconductor chips from a semiconductor wafer using an adhesive sheet that can cause irregularities on the adhesive surface of the agent layer (X1).
The production method of the present invention has the following steps (1) to (3).
Step (1): A step of attaching the adhesive surface of the first adhesive layer (X1) to a hard support and attaching the adhesive surface of the second adhesive layer (X2) to the surface of a 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.

[Structure of 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 structure 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 comprises a substrate (Y) comprising at least an expandable substrate layer (Y1) and a non-expandable substrate layer (Y2) as shown in FIG. A pressure-sensitive adhesive sheet 1a having a first pressure-sensitive adhesive layer (X1) and a second pressure-sensitive adhesive layer (X2) on both sides of a material (Y) is exemplified.

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

In addition, in the pressure-sensitive adhesive sheet used in one aspect 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 the structure, a structure in which a release material having both sides subjected to release treatment is laminated on the adhesive surface of one of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) and wound into a roll. may be
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.

Further, for example, in the pressure-sensitive adhesive sheet 1a shown in FIG. When the peeling forces of the peeling materials are about the same, the pressure-sensitive adhesive sheet 1a is divided and peeled off along with the two peeling materials by pulling both of the peeling materials outward and trying to peel them off. harm may occur.
Therefore, 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 to be adhered to each other. It is preferable to use two designed release materials.

By the way, the pressure-sensitive adhesive sheet used in the production method of the present invention is adjusted so that the expansion of the expandable particles can cause unevenness on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1).
For example, in the pressure-sensitive adhesive sheet 1a shown in FIG. 1(a), the first pressure-sensitive adhesive layer (X1) is laminated on the expandable base layer (Y1) containing expandable particles, and the non-expandable base layer (Y2) is laminated. It has the structure which laminated|stacked the 2nd adhesive layer (X2) on it.
In the pressure-sensitive adhesive sheet 1a, when the expandable particles in the expandable base layer (Y1) expand, the surface of the expandable base layer (Y1) becomes uneven, and the first pressure-sensitive adhesive layer is in contact with the surface. (X1) is pushed up by the unevenness, and as a result, the adhesive surface of the first pressure-sensitive adhesive layer (X1) may also have unevenness.
In the production method of the present invention, the adhesive surface of the first adhesive layer (X1) is attached to the hard support as in step (1) described above.
In the above step (3), when the expandable particles are expanded, unevenness is generated on the adhesive surface of the first adhesive layer (X1), and the contact area with the hard support is reduced. and the first pressure-sensitive adhesive layer (X1) can be easily separated collectively with a slight force at the interface P.
In addition, when the expandable particles are expanded, even at the interface between the expandable base layer (Y1) and the non-expandable base layer (Y2), they can be easily separated collectively with a slight force. may be adjusted.

On the other hand, as in the above-described step (1), the surface of the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2), and in step (2), the semiconductor wafer is divided to form a plurality of semiconductors. tip. 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) remain attached, and the hard support and the first pressure-sensitive adhesive layer are separated from each other. It is separated at the interface P with the agent layer (X1).
That is, the plurality of semiconductor chips must be held on the second adhesive layer (X2) of the adhesive sheet when separated from the hard support.
For this reason, it is preferable that the adhesive surface of the second adhesive layer (X2) is adjusted so that the formation of irregularities is suppressed so that the 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), a non-expanding base layer (Y2) is provided on the surface of the expandable base layer (Y1) opposite to the first pressure-sensitive adhesive layer (X1). A second pressure-sensitive adhesive layer (X2) is laminated on the surface of the non-expanding base material layer (Y2).
In the pressure-sensitive adhesive sheet 1a, when the expandable particles expand, the non-expandable base layer (Y2) exists, so the stress from the expandable base layer (Y1) due to the expansion of the expandable particles is The non-expanding base layer (Y2) absorbs. As a result, the formation of irregularities on the adhesive surface of the second adhesive layer (X2) laminated on the non-expanding base 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. 1(b), the first non-expanding It is preferable to adjust the storage modulus E' of the base material layer (Y2-1) to be low.
On the other hand, the second non-thermally expandable base layer (Y2-2) is formed so that the formation of irregularities on the adhesive surface of the second adhesive layer (X2) is suppressed when the expandable particles expand. It is preferable to adjust the storage elastic modulus E′ 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 compared to the second non-thermally expandable base layer (Y2-1) when the expandable particles expand. It is preferable to adjust the storage elastic modulus E' lower than -2).

By the way, using a 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 attached to a hard support, and the other pressure-sensitive adhesive layer is attached. When manufacturing semiconductor chips by attaching a semiconductor wafer thereon, the expandable pressure-sensitive adhesive layer to be adhered to the hard support contains expandable particles, so the adhesive strength tends to be insufficient.

A decrease in the adhesive strength of the expandable pressure-sensitive adhesive layer to the hard support prevents the semiconductor wafer from being sufficiently fixed to the hard support. Malfunctions such as chipping of the ends are likely to occur.
In addition, in the production of semiconductor chips by the Stealth Dicing (registered trademark, hereinafter the same) method, it is necessary to provide modified regions inside the semiconductor wafer. becomes easier. Here, if the semiconductor wafer is not sufficiently fixed to the rigid support, warping of the semiconductor wafer cannot be suppressed, which causes chip cracking and the like.

On the other hand, it is conceivable to avoid the above problems by selecting an adhesive resin and increasing the adhesive strength of the adhesive layer to which the semiconductor wafer is attached and the expansive adhesive layer.
However, when the adhesive layer to which the semiconductor wafer is attached has a high adhesive strength, it may be difficult to separate the resulting plurality of semiconductor chips from the adhesive layer.
Further, when the expandable pressure-sensitive adhesive layer has a high adhesive strength, when the expandable particles are expanded to separate the double-sided pressure-sensitive adhesive sheet from the hard support, one part of the expandable pressure-sensitive adhesive layer is applied to the surface of the hard support. Some parts may remain, and it is necessary to wash the support, which is a factor in lowering productivity. Moreover, when peeling off the double-sided pressure-sensitive adhesive sheet attached to the hard support, a certain amount of force is required, and it may be difficult to peel off easily all at once.

On the other hand, the pressure-sensitive adhesive sheet used in the production method of the present invention has a substrate (Y) comprising at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2). The pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) is adjusted so that unevenness is formed when the adhesive particles expand.
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 edge of the chip is chipped. Such adverse effects can be effectively suppressed, and the yield can be improved.
In addition, when separating the hard support and the attached pressure-sensitive adhesive sheet, it is possible to easily separate them all at once, suppress contamination of the hard support after separation, and omit the step of washing the support. enable and improve productivity.
Furthermore, the degree of freedom in selecting the pressure-sensitive adhesive composition that is the material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) is also high.

[Various physical properties of the adhesive sheet]
In the pressure-sensitive adhesive sheet used in one aspect of the present invention, the expansion of the expandable particles causes irregularities on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1) attached to the hard support, and the hard support and the first pressure-sensitive adhesive At the interface P with the layer (X1), it becomes possible to easily separate them collectively with a slight force.
Here, in the adhesive sheet used in one aspect of the present invention, the peel 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/ 25 mm, more preferably 0 to 150 mN/25 mm, still more preferably 0 to 100 mN/25 mm, even more preferably 0 to 50 mN/25 mm.
When the peel force (F ₁ ) is 0 mN/25 mm, even if the peel force is measured by the method described in Examples, the peel force may be too small to be measured.

On the other hand, before the expansion of the expandable particles, the first pressure-sensitive adhesive layer suppresses the occurrence of chipping at the ends of the chips when manufacturing a plurality of semiconductor chips from the semiconductor wafer and improves the yield. The higher the adhesive strength of (X1), the better.
From the above viewpoint, in the pressure-sensitive adhesive sheet used in one aspect of the present invention, the peel force (F ₀ ) when separating at the interface P before expansion of the expandable particles is preferably 0.05 to 10.0 N/25 mm, It is more preferably 0.1 to 8.0 N/25 mm, still more preferably 0.15 to 6.0 N/25 mm, still more preferably 0.2 to 4.0 N/25 mm.
In addition, the said peeling force ( _F0 ) can also be regarded as the adhesive force of the 1st adhesive layer (X1) with respect to a hard support body.

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

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

In addition, in the pressure-sensitive adhesive sheet used in one aspect 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 .2 to 8.0 N/25 mm, more preferably 0.4 to 6.0 N/25 mm, even more preferably 0.5 to 4.0 N/25 mm.
As used herein, the adhesive strength of the second adhesive layer (X2) means a value measured by the method described in Examples.
Each layer constituting the pressure-sensitive adhesive sheet used in one embodiment of the present invention will be described below.

<Base material (Y)>
The substrate (Y) of the pressure-sensitive adhesive sheet used in one aspect of the present invention includes at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2).
Further, as the base material (Y), an expandable base material layer (Y1) and a non-expandable base material layer (Y2) are laminated one by one like the adhesive sheet 1a shown in FIG. Like the adhesive sheet 1b shown in FIG. 1(b), the first non-thermally expandable base layer (Y2-1) and the second A configuration in which a non-thermally expandable base material layer (Y2-2) is provided may also be used.

The substrate (Y) of the pressure-sensitive adhesive sheet used in one aspect of the present invention has a configuration in which an adhesive layer is provided between the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2). may
For example, in the case of the configuration of the pressure-sensitive adhesive sheet 1b shown in FIG. An adhesive layer may be provided between the flexible substrate layer (Y2-2).
By providing the adhesive layer, it is possible to improve the interlayer adhesion between the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2).
The adhesive layer can be formed from a general adhesive or an adhesive composition that is the material for forming the first adhesive layer (X1) and the second adhesive layer (X2).

In one aspect of the present invention, the expansion of the expandable particles causes unevenness on the adhesive surface of the first adhesive layer (X1), while suppressing the formation of unevenness on the adhesive surface of the second adhesive layer (X2). From the viewpoint of making a pressure-sensitive adhesive sheet that can be .
In this embodiment, the substrate (Y), the expandable substrate layer (Y1), the adhesive layer, and the non-expandable substrate layer (Y2) possessed by the pressure-sensitive adhesive sheet 1a shown in FIG. A base material (Y) formed by laminating with is mentioned.
Examples of the material for forming the adhesive layer include the same adhesive composition as the material for forming the adhesive layer of the transfer tape described later.

Both the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2) that constitute the substrate (Y) are non-adhesive layers.
In the present invention, whether or not the layer is non-adhesive is determined if the probe tack value measured according to JIS Z0237: 1991 is less than 50 mN / 5 mmφ against the surface of the target layer. is judged to be the "non-sticky layer".
The probe tack values on the surfaces of the expandable base layer (Y1) and the non-expandable base layer (Y2) of the pressure-sensitive adhesive sheet (I) used in one aspect 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 this specification, a specific method for measuring the probe tack value on the surface of the thermally expandable substrate is according to the method described in Examples.

In the adhesive sheet used in one aspect 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, still more preferably 40 to 500 μm. be.

The thickness of the expandable substrate (Y1) before expansion of the expandable particles is preferably 10-1000 μm, more preferably 20-700 μm, even more preferably 25-500 μm, and even more preferably 30-300 μm.
The thickness of the non-expandable substrate (Y2) is preferably 10-1000 μm, more preferably 20-700 μm, still more preferably 25-500 μm, still more preferably 30-300 μm.
In this specification, for example, like the adhesive sheet 1b shown in FIG. In this case, the thickness of the expandable substrate (Y1) or the non-expandable substrate (Y2) means the thickness of each layer.

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

In the pressure-sensitive adhesive sheet used in one aspect of the present invention, the expandable base layer (Y1) before expansion of the expandable particles and the first pressure-sensitive adhesive layer (X1) directly laminated on the expandable base 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 even more preferably 5.0 or more. Also, it is preferably 1000 or less, more preferably 200 or less, even more preferably 60 or less, and even more preferably 30 or less.

In addition, in the pressure-sensitive adhesive sheet used in one aspect of the present invention, the thickness of the non-expanding base layer (Y2) and the second pressure-sensitive adhesive layer (X2) directly laminated on the non-expanding base 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 is preferably 20 or less, more preferably 10 or less. , more preferably 5 or less.

The expandable base layer (Y1) and the non-expandable base layer (Y2) that constitute the base (Y) are described below.

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

In addition, from the viewpoint of improving the interlayer adhesion between the expandable base layer (Y1) and other layers to be laminated, the surface of the expandable base layer (Y1) is subjected to an oxidation method, a roughening method, or the like. A treatment, an easy-adhesion treatment, or a primer treatment may be applied.
Examples of oxidation methods include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, and ultraviolet irradiation treatment. Examples of roughening methods include sandblasting and solvent treatment. etc.

The expandable particles contained in the expandable base material layer (Y1) may be particles that expand by performing a predetermined treatment. For example, thermally expandable particles that expand when heated to a predetermined temperature or higher, Examples include UV expandable particles that expand by generating gas inside the particles by absorbing a predetermined amount of ultraviolet rays.

The maximum volumetric expansion rate of the expandable particles is preferably 1.5 to 100 times, more preferably 2 to 80 times, even more preferably 2.5 to 60 times, still more preferably 3 to 40 times.

The mean particle size 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, still more preferably 10 to 50 μm.
The average particle size of the expandable particles is the volume-median particle size ( _D50 ), which is measured using a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name "Mastersizer 3000"). In the particle distribution of the expandable particles obtained, the particle size corresponds to a cumulative volume frequency of 50% 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 even more preferably 30 to 80 μm. .
The 90% particle diameter (D ₉₀ ) of the expandable particles is the particle distribution of the expandable particles measured using a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name "Mastersizer 3000"). , means the particle size corresponding to 90% of the cumulative volume frequency calculated from the smaller particle size of the expandable particles.

In one aspect 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 initiation temperature (t) of 60 to 270° C. More preferably, the flexible substrate layer (Y1-1) satisfies the following requirement (1).
Requirement (1): The storage elastic modulus E′(t) of the thermally expandable base layer (Y1-1) at the expansion start temperature (t) of the thermally expandable particles is 1.0×10 ⁷ Pa. It is below.
In this specification, the storage elastic modulus E' of the thermally expandable base layer (Y1-1) at a given temperature means a value measured by the method described in Examples.

Requirement (1) above can be said to be an index indicating the rigidity of the thermally expandable substrate layer (Y1-1) immediately before the thermally expandable particles expand.
That is, when the thermally expandable particles expand, if the thermally expandable base layer (Y1-1) has flexibility to the extent that the above requirement (1) is satisfied, the thermally expandable base layer (Y1 The surface of -1) is likely to be uneven, and the adhesive surface of the first adhesive layer (X1) is also likely to be uneven. As a result, the interface P between the hard support and the first pressure-sensitive adhesive layer (X1) can be easily separated collectively with a slight force.

The storage elastic modulus E′(t) defined in requirement (1) of the thermally expandable substrate layer (Y1-1) is preferably 9.0×10 ⁶ Pa or less, more preferably 8.0 from the above viewpoint. ×10 ⁶ Pa or less, more preferably 6.0 × 10 ⁶ Pa or less, still more preferably 4.0 × 10 ⁶ Pa or less.
In addition, it suppresses the flow of the expanded thermally expandable particles, improves the shape retention of the unevenness generated on the surface of the thermally expandable base layer (Y1-1), and improves the adhesive surface of the first adhesive layer (X1). From the viewpoint of making it easier to generate unevenness, the storage elastic modulus E′(t) defined in requirement (1) of the thermally expandable base layer (Y1-1) is preferably 1.0×10 ³ Pa or more, and more It is preferably 1.0×10 ⁴ Pa or more, more preferably 1.0×10 ⁵ Pa or more.

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

By using the thermally expandable base 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). Also, excessive sinking of the semiconductor wafer into the second adhesive layer (X2) can be prevented.

From the above point of view, the storage elastic modulus E′ (23) of the thermally expandable base layer (Y1-1) defined in 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, still more preferably 1.0×10 ⁸ to 1.0×10 11 Pa 0×10 ¹⁰ Pa.

Thermally expandable particles contained in the thermally expandable substrate layer (Y1-1) are preferably thermally expandable particles having an expansion start temperature (t) of 60 to 270°C.
In this specification, the expansion start temperature (t) of thermally expandable particles means a value measured based on the following method.
[Method for measuring expansion start temperature (t) of thermally expandable particles]
An aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm was filled with 0.5 mg of thermally expandable particles to be measured, and an aluminum lid (5.6 mm in diameter and 0.6 mm in thickness) was placed thereon. 1 mm) is placed on the sample.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured while a force of 0.01 N is applied to the sample from the top of the aluminum lid with a pressurizer. Then, while applying a force of 0.01 N by the pressurizer, heat is applied from 20° C. to 300° C. at a temperature increase rate of 10° C./min, and the amount of displacement in the vertical direction of the pressurizer is measured. Let the displacement start temperature be the expansion start temperature (t).

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

Examples of encapsulated components encapsulated in the outer shell include propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane, cyclobutane, and 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, 2,6,10,14-tetramethylpentadecane, cyclotridecane, heptylcyclohexane, n-octylcyclohexane , cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane and the like.
These inclusion 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, the resin composition (y) may contain additives for base materials, if necessary, as long as the effects of the present invention are not impaired.
Examples of base material additives include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, colorants, and the like.
These base material additives may be used alone, or two or more of them may be used in combination.
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 20 parts by mass, relative to 100 parts by mass of the resin. 10 parts by mass.

The expandable particles contained in the resin composition (y), which is the 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, still more preferably 10 to 40% by mass, relative to the total amount (100% by mass) of the active ingredients of the resin composition (y). 30% by weight, more preferably 15 to 25% by weight.

The resin contained in the resin composition (y), which is the material for forming the expandable substrate 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, in the process of forming the expandable substrate layer (Y1) from the resin composition (y), the adhesive resin is a polymerizable compound. and the resulting resin becomes a non-tacky resin, and the expandable substrate layer (Y1) containing the resin becomes non-tacky.

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 10,000 to 700,000, and still more preferably 10,000 to 500,000.
Further, when the resin is a copolymer having two or more structural units, the form of the copolymer is not particularly limited, and may be a block copolymer, a random copolymer, or a graft copolymer. may be

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

In one aspect of the present invention, the resin contained in the resin composition (y) is acrylic urethane from the viewpoint of forming an expandable base layer (Y1) in which irregularities are easily formed on the surface when the expandable particles are expanded. It preferably contains one or more selected from a system resin and an olefin system resin.
Moreover, as the acrylic urethane-based 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) that forms the main chain of the acrylic urethane resin (U1) include reaction products of polyols and polyvalent isocyanates.
In addition, it is preferable that the urethane prepolymer (UP) is obtained by subjecting the urethane prepolymer (UP) to a chain extension reaction using a chain extension agent.

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

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

Examples of alkylene type diols include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol and 1,6-hexanediol; ethylene glycol, propylene glycol, 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;

Examples of carbonate-type diols 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.

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

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

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

In one aspect of the present invention, the urethane prepolymer (UP), which is 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. Urethane prepolymers are preferred.
As a method for introducing ethylenically unsaturated groups at both ends of the linear urethane prepolymer, an NCO group at the terminal of the linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound, and a hydroxyalkyl (meth)acrylate and a method of reacting with.

Hydroxyalkyl (meth)acrylates include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxy Butyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like can be mentioned.

At least (meth)acrylic acid ester is included as the vinyl compound that becomes the side chain of the acrylic urethane resin (U1).
As the (meth)acrylic acid ester, one or more selected from alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates is preferable, and it is more preferable to use alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates together.

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

The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is preferably 1-24, more preferably 1-12, even more preferably 1-8, and even more preferably 1-3.

Examples of hydroxyalkyl (meth)acrylates include the same hydroxyalkyl (meth)acrylates used for introducing ethylenically unsaturated groups to both ends of the linear urethane prepolymer described above.

Examples of vinyl compounds other than (meth)acrylic esters include aromatic hydrocarbon-based vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. , (meth)acrylonitrile, N-vinylpyrrolidone, (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, meta(acrylamide) and other polar group-containing monomers;
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 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, based on the total amount (100% by mass) of the vinyl compound. 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

In the acrylic urethane resin (U1) used in one aspect 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, still more preferably 35 /65 to 55/45.

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

Specific olefin resins include, for example, ultra-low density polyethylene (VLDPE, density: 880 kg/m ³ or more and less than 910 kg/m ³ ), low density polyethylene (LDPE, density: 910 kg/m ³ or more and less than 915 kg/m 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), polyethylene resin such as linear low density polyethylene; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefin elastomer (TPO); ethylene-vinyl acetate copolymer (EVA); olefinic terpolymer; and the like.

In one aspect of the present invention, the olefin-based resin may be a modified olefin-based resin further subjected to one or more modifications selected from acid modification, hydroxyl modification, and acrylic modification.

For example, the acid-modified olefin resin obtained by subjecting an olefin resin to acid modification is a modified polymer obtained by graft-polymerizing an unsaturated carboxylic acid or its anhydride to the above-described unmodified olefin resin. is mentioned.
Examples of unsaturated carboxylic acids or anhydrides thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth)acrylic acid, maleic anhydride, and itaconic anhydride. , glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornenedicarboxylic anhydride, tetrahydrophthalic anhydride and the like.
The unsaturated carboxylic acid or its anhydride may be used alone, or two or more of them may be used in combination.

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

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

(Resins other than acrylic urethane resins and olefin resins)
In one aspect 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; Polyester resin such as phthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resin; polymethylpentene; sulfide; polyimide-based resins such as polyetherimide and polyimide; polyamide-based resins; acrylic resins;

However, from the viewpoint of forming an expandable substrate layer (Y1) in which irregularities are easily formed on the surface when the expandable particles expand, the resin composition (y) contains a resin other than the acrylic urethane resin and the olefin resin. The smaller the ratio, the better.
The content of the resin other than the acrylic urethane resin and the olefin resin is preferably less than 30 parts by mass, more preferably 20 parts by mass, with respect to 100 parts by mass of the total resin contained in the resin composition (y). less than 10 parts by weight, 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 with a mass average molecular weight (Mw) of 50000 or less, an energy ray-polymerizable monomer, and the above-described thermally expandable particles are blended, A non-solvent type resin composition (y1) containing no solvent is exemplified.
In the solvent-free resin composition (y1), no solvent is blended, but the energy ray-polymerizable monomer contributes to improving the plasticity of the oligomer.
By irradiating the coating film formed from the solvent-free resin composition (y1) with energy rays, an expandable substrate layer (Y1) is formed in which irregularities are easily formed on the surface when the expandable particles expand. In particular, it is easy to form a thermally expandable base layer (Y1-1) that satisfies the above requirements (1) and (2).

The type, shape, and compounding amount (content) of the expandable particles to be blended in the solvent-free resin composition (y1) are the same as those for the resin composition (y), and are as described above.

The weight average molecular weight (Mw) of the oligomer contained in the solventless resin composition (y1) is 50,000 or less, preferably 1,000 to 50,000, more preferably 2,000 to 40,000, still more preferably 3,000 to 35,000. It is more preferably 4,000 to 30,000.

As the oligomer, among the resins contained in the above resin composition (y), those having an ethylenically unsaturated group with a mass average molecular weight of 50000 or less may be used, but the above urethane prepolymer (UP ) is preferred.
A modified olefinic resin having an ethylenically unsaturated group can also be used as the oligomer.

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

Energy beam-polymerizable monomers include, for example, 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; Examples include heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam.
These energy ray-polymerizable monomers may be used alone or in combination of two or more.

The blending ratio of the oligomer and the energy ray-polymerizable monomer (the oligomer/energy ray-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 aspect of the present invention, the solventless resin composition (y1) preferably further contains a photopolymerization initiator.
By containing a photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.

Photopolymerization initiators include, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyro nitrile, dibenzyl, diacetyl, 8-chloroanthraquinone and the like.
These photopolymerization initiators may be used alone or in combination of two or more.

The amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and further preferably 0.01 to 5 parts by mass, based on the total amount (100 parts by mass) of the oligomer and the energy ray-polymerizable monomer. It is preferably 0.02 to 3 parts by mass.

<Non-expandable base layer (Y2)>
Examples of materials for forming the non-expanding base material layer (Y2) constituting the base material (Y) include paper materials, resins, and metals.
Examples of the paper material include thin paper, medium quality paper, fine paper, impregnated paper, coated paper, art paper, parchment paper, glassine paper, and the like.
Examples of resins 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; polyester resins such as butylene terephthalate and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyether sulfone; polyphenylene sulfide; polyimide-based resins such as polyetherimide and polyimide; polyamide-based resins; acrylic resins;
Examples of metals include aluminum, tin, chromium, and titanium.

These forming materials may be composed of one type, or two or more types may be used in combination.
The non-expandable base material layer (Y2) using two or more kinds of forming materials in combination includes a paper material laminated with a thermoplastic resin such as polyethylene, or a resin film or sheet containing a resin and a metal film formed on the surface thereof. 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 the interlayer adhesion between the non-expanding base layer (Y2) and other layers to be laminated, when the non-expanding base layer (Y2) contains a resin, the non-expanding base layer (Y2) The surface of Y2) may also be subjected to a surface treatment such as an oxidation method or roughening method, an adhesion-facilitating treatment, or a primer treatment, as in the case of the expandable base layer (Y1) described above.

In addition, when the non-expanding base material layer (Y2) contains a resin, it may contain the aforementioned base material additives that may be contained in the resin composition (y) together with the resin.

The non-expanding base layer (Y2) is located farther from the first pressure-sensitive adhesive layer (X1) than the expandable base layer (Y1), and the expandable base layer (Y1 ) and the first pressure-sensitive adhesive layer (X1), the non-expanding base layer (Y2) does not exist, and the non-expanding base layer (Y2) when the expandable particles expand The storage elastic modulus E′ of is preferably larger than the storage elastic modulus E′ of the expandable base layer (Y1) when the expandable particles expand. Thus, since the non-expandable base layer (Y2) is not present between the expandable base layer (Y1) and the first pressure-sensitive adhesive layer (X1), the expandable particles expand to form the expandable base layer. The unevenness generated on the surface of (Y1) is transmitted to the first adhesive layer (X1) without interposing the non-expanding base layer (Y2), and the adhesive surface of the first adhesive layer (X1) Also, irregularities are likely to occur. In addition, when the expandable particles expand, the storage elastic modulus E′ of the non-expandable base layer (Y2) is greater than the storage elastic modulus E′ of the expandable base layer (Y1). At the time of expansion, the surface of the expandable base layer (Y1) on the non-expandable base layer (Y2) side is suppressed from being uneven. The surface of the pressure-sensitive adhesive layer (X1) is likely to be uneven, and therefore the adhesive surface of the first pressure-sensitive adhesive layer (X1) is also likely to be uneven.
The storage elastic modulus E′ of the non-expanding base material layer (Y2) when the expandable particles expand is, as described above, from the viewpoint of facilitating the formation of unevenness on the adhesive surface of the first adhesive layer (X1). , preferably 1.0 MPa or more, from the viewpoint of ease of application work and peeling work, from the viewpoint of generating unevenness on the adhesive surface of the second pressure-sensitive adhesive layer (X2), or from the viewpoint of handling in a roll form. From the viewpoint of easiness, it is preferably 1.0×10 ³ MPa or less. From this point of view, the storage elastic modulus E′ of the non-expandable base 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 above point of view and from the point of view of preventing misalignment when attaching the semiconductor wafer to the adhesive surface of the second adhesive layer (X2), the storage elastic modulus of the non-expanding base 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, still more preferably 5.0×10 ² to 5.0×10 ³ MPa.
The non-expanding base layer (Y2) is a non-expanding layer determined based on the method described above.
Therefore, the volume change rate (%) of the non-expandable base layer (Y2) calculated from the above formula is less than 5% by volume, preferably less than 2% by volume, and more preferably less than 1% by volume. , more preferably less than 0.1% by volume, and even more preferably less than 0.01% by volume.

In addition, the non-expandable base layer (Y2) may contain thermally expandable particles as long as the volume change rate is within the above range. For example, by selecting a resin contained in the non-expandable base material layer (Y2), it is possible to adjust the volume change rate within the above range even if thermally expandable particles are contained.
However, the content of the thermally expandable particles in the non-expandable base layer (Y2) is preferably as low as possible.
A specific content of the thermally expandable particles is usually less than 3% by mass, preferably less than 1% by mass, more preferably less than 1% by mass, relative to the total mass (100% by mass) of the non-expandable base material layer (Y2). Less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

<First adhesive layer (X1), second adhesive layer (X2)>
The pressure-sensitive adhesive sheet used in one aspect 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 adhesive surface of the first adhesive layer (X1) is attached to the hard support, and the adhesive surface of the second adhesive layer (X2) is attached to the semiconductor wafer.

The first pressure-sensitive adhesive layer (X1) has high adhesion to the hard support before expansion of the expandable particles contained in the expandable base layer (Y1), and sufficiently fixes the semiconductor wafer to the hard support. A property that can be used is required.
From this point of view, 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. and more preferably 1.0×10 ⁷ Pa or less.

On the other hand, when the expandable particles in the expandable base layer (Y1) expand, the unevenness generated on the surface of the expandable base layer (Y1) is also applied to the adhesive surface of the first adhesive layer (X1). It is also required to be rigid enough to form.
From this point of view, 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. and more preferably 1.0×10 ⁵ Pa or more.

In addition, the second adhesive layer (X2) is required not only to adhere to the semiconductor wafer, but also to adhere to the semiconductor chips obtained by cutting the semiconductor wafer. 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 0×10 ⁴ to 5.0×10 ⁷ Pa, more preferably 1.0×10 ⁵ to 1.0×10 ⁷ Pa.
In the present specification, the storage shear modulus G'(23) of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) means a value measured by the method described in Examples. .

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

The thickness of the second pressure-sensitive adhesive layer (X2) is preferably 1-60 μm, more preferably 2-50 μm, even more preferably 3-40 μm, still more preferably 5-30 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, the pressure-sensitive adhesive composition (x) may contain additives for pressure-sensitive adhesive such as a cross-linking agent, a tackifier, a polymerizable compound, and a polymerization initiator, if necessary.
Each component contained in the pressure-sensitive adhesive composition (x) is described below.

(adhesive resin)
The adhesive resin used in one embodiment of the present invention may be a polymer that has adhesiveness by itself 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 aspect of the present invention is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and still more preferably 30,000 from the viewpoint of improving adhesive strength. ~1 million.

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

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 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 irradiation with energy rays. Therefore, the obtained semiconductor chip can be easily picked up from the second adhesive layer (X2).
Examples of the polymerizable functional group include a (meth)acryloyl group and a vinyl group.
Moreover, although an ultraviolet-ray and an electron beam are mentioned as an energy beam, an ultraviolet-ray is preferable.
The material for forming the pressure-sensitive adhesive layer whose adhesive strength can be reduced by irradiation with energy rays may be an energy-ray-curable pressure-sensitive adhesive composition containing a monomer or oligomer having a polymerizable functional group.

These energy ray-curable pressure-sensitive adhesive compositions preferably further contain a photopolymerization initiator.
By containing a photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.
Examples of the photopolymerization initiator include the same as those blended in the solventless resin composition (y1) described above.
The content of the photopolymerization initiator is preferably 0.01 to 10 parts by weight, more preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the energy ray-curable adhesive resin or 100 parts by weight of the monomer or oligomer having a polymerizable functional group. 0.03 to 5 parts by mass, more preferably 0.05 to 2 parts by mass.

In one aspect of the present invention, the adhesive resin preferably contains an acrylic resin from the viewpoint of exhibiting excellent adhesive strength. 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 facilitate the formation of 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). ~100% by mass, more preferably 70 to 100% by mass, and even 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 60 to 98 mass %, more preferably 70 to 95 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 cross-linking agent.
The cross-linking agent reacts with the adhesive resin having a functional group to cross-link the adhesive resins with each other using the functional group as a cross-linking starting point.

Examples of cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.
These cross-linking agents may be used alone or in combination of two or more.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoints of increasing the cohesive force and improving the adhesive strength, and from the viewpoints of availability and the like.

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

(Tackifier)
In one aspect of the present invention, the pressure-sensitive adhesive composition (x) may further contain a tackifier from the viewpoint of further improving the adhesive strength.
As used herein, the term "tackifier" refers to a component that supplementarily improves the adhesive strength of the adhesive resin described above, and refers to an oligomer having a weight-average molecular weight (Mw) of less than 10,000. It is distinguished from the synthetic resin.
The weight average molecular weight (Mw) of the tackifier is preferably 400-10,000, more preferably 500-8,000, still more preferably 800-5,000.

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

The softening point of the tackifier is preferably 60 to 170°C, more preferably 65 to 160°C, still more preferably 70 to 150°C.
In addition, in this specification, the "softening point" of a tackifier means the value measured based on JISK2531.
The tackifiers may be used alone, or two or more of them having different softening points and structures may be used in combination.
When two or more tackifiers are used, the weighted average of the softening points of the tackifiers preferably falls within the above range.

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

(Adhesive additive)
In one aspect of the present invention, the pressure-sensitive adhesive composition (x) contains additives for pressure-sensitive adhesives that are commonly used in pressure-sensitive adhesives, in addition to the above additives, within a range that does not impair the effects of the present invention. You may have
Examples of such adhesive additives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, antistatic agents, and the like. are mentioned.
In addition, these additives for pressure-sensitive adhesives may be used alone, respectively, or two or more of them may be used in combination.

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

The first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) are preferably non-expansive pressure-sensitive adhesive layers. Therefore, it is preferable that the content of expandable particles in the pressure-sensitive adhesive composition (x), which is the material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2), is as low as possible.
The content of the expandable particles is the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x), or the total weight 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, even more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

<Release material>
The pressure-sensitive adhesive sheet used in one aspect of the present invention may further have a release material 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 subjected to double-sided release treatment, a release sheet subjected to single-sided release treatment, or the like is used.

Base materials for release materials include, for example, papers such as woodfree paper, glassine paper and kraft paper; polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin; olefins such as polypropylene resin and polyethylene resin; plastic films such as resin films; and the like.

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

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

[Each step of the method for manufacturing a semiconductor chip of the present invention]
The production method of the present invention is a method for producing semiconductor chips from a semiconductor wafer using the adhesive sheet described above, and comprises the following steps (1) to (3).
Step (1): A step of attaching the adhesive surface of the first adhesive layer (X1) to a hard support and attaching the adhesive surface of the second adhesive layer (X2) to the surface of a semiconductor wafer.
• Step (2): a step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The expandable particles are expanded to adhere the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) to the interface between the hard support and the first pressure-sensitive adhesive layer (X1). 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 pre-dicing method.

In addition, 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 of the plurality of semiconductor chips opposite to the circuit surface is covered with a base film and an adhesive layer and / or an adhesive layer. removing the adhesive sheet from the semiconductor chip after attaching it to the transfer tape provided;
Step (5): A step of stretching the transfer tape in the MD direction to widen the distance between the plurality of semiconductor chips.
Step (6): A step of separating a plurality of semiconductor chips from the transfer tape to obtain semiconductor chips.

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).
The steps (1) to (4) will be described below with reference to FIGS. 2 and 3 as appropriate.

<Step (1)>
FIG. 2(a) is a schematic cross-sectional view in step (1) showing a state in which a semiconductor wafer 60 is attached to a hard support 50 using the adhesive sheet 1a shown in FIG. 1(a).
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 adhesive surface of the second adhesive layer (X2) is formed with the circuit of the semiconductor wafer 60. It is preferable to affix to the circuit surface 61 which has been printed.
FIG. 2 shows an embodiment using the pressure-sensitive adhesive sheet 1a shown in FIG. and a semiconductor wafer are laminated in this order, and the adhesive surface of the first adhesive layer (X1) of the adhesive sheet is attached to the hard support, and the adhesive surface of the second adhesive layer (X2) is attached to the circuit surface of the semiconductor wafer. preferably.

The hard support is preferably attached to the entire adhesive surface of the first adhesive layer (X1) of the adhesive sheet. Therefore, the hard support is preferably plate-like.
In addition, as shown in FIG. 2, the area of the surface of the hard support to be attached to the first pressure-sensitive adhesive layer (X1) is preferably equal to or greater than the area of the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X1).

Materials constituting the hard support include, for example, metallic 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, and polyamideimide. resin materials such as resins; composite materials such as glass epoxy resins; among these, SUS, glass, and silicon wafers are preferred.
Engineering plastics include nylon, polycarbonate (PC), and polyethylene terephthalate (PET).
Super engineering plastics include polyphenylene sulfide (PPS), polyethersulfone (PES), polyetheretherketone (PEEK), and the like.

The thickness of the hard support is preferably 20 μm or more and 50 mm or less, 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 the chip crack prevention performance.
In this specification, the Young's modulus of the rigid support is a value measured at room temperature (25° C.) according to the static Young's modulus test method of JIS Z2280:1993.

The surface of the semiconductor wafer to be 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 the “back surface”) is subjected to grinding treatment in the next step to divide the semiconductor wafer into a plurality of semiconductor chips. It is preferable that the flat surface is not formed.
By attaching 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 made of silicon, SiC (silicon carbide), gallium, arsenic, etc., by an etching method, a lift-off method, or the like. can be done.

In addition, the semiconductor wafer is processed to form a modified region inside the semiconductor wafer for applying the stealth dicing method, and grooves are formed in the thickness direction from the surface of the semiconductor wafer for applying the pre-dicing method. need to be processed.
The circuit surface of the semiconductor wafer previously subjected to these treatments may be attached to the adhesive surface of the second adhesive layer (X2). Further, in this step, after the circuit surface of the semiconductor wafer which has not been subjected to these treatments is attached to the adhesive surface of the second adhesive layer (X2), these treatments may be performed from the back surface of the semiconductor wafer. .

In particular, the process of forming a modified region inside the semiconductor wafer for application to the stealth dicing method can be performed after the circuit surface of the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2). preferable.
The circuit surface of the semiconductor wafer is attached to the adhesive surface of the second adhesive layer (X2), and then the modified region is formed, so that the semiconductor wafer is attached to the hard support via the adhesive sheet. , it is possible to effectively suppress warping of the semiconductor wafer that may occur after the modified region is formed.

When manufacturing semiconductor chips by the stealth dicing method, as a process for forming a modified region inside the semiconductor wafer, the back surface of the semiconductor wafer is used as the oblique incident surface of the laser beam, and the focal point is aligned with the inside of the workpiece. A method of forming a modified region by multiphoton absorption by irradiating light can be used. 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 process of forming grooves in the thickness direction from the surface of the semiconductor wafer for applying the pre-dicing method may be performed before or after attaching the semiconductor wafer to the second adhesive layer (X2). may
In the case of manufacturing semiconductor chips by the pre-dicing method, the process of forming grooves 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.

It should be noted that step (1) is preferably performed in an environment in which the expandable particles do not expand.
For example, when thermally expandable particles are used as the expandable particles, step (1) may be performed under temperature conditions below the expansion start temperature (t) of the thermally expandable particles. is preferably carried out in an environment of 0 to 80° C. (in an environment below the expansion initiation temperature (t) when the expansion initiation temperature (t) is 60 to 80° C.).

<Step (2)>
Step (2) is a step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
As a method of dividing the semiconductor wafer, a method of grinding the back surface of the semiconductor wafer to singulate the semiconductor wafer into a plurality of semiconductor chips is preferable.
FIG. 2(b) 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 the back surface on which the circuit is not formed on the side opposite to the circuit surface, and the semiconductor wafer is divided into a plurality of semiconductor chips. is the process of obtaining
In the stealth dicing method, the modified region is an embrittled portion of the semiconductor wafer. is a region that becomes a starting point for breaking down and singulating into semiconductor chips. As a result, the semiconductor wafer is diced along the modified regions and crack lines, and singulated as a plurality of semiconductor chips.

Further, in the pre-dicing method, the semiconductor wafer having grooves formed in advance in the thickness direction is ground on the back surface opposite to the circuit surface, on which no circuit is formed, to divide the semiconductor wafer. Then, it becomes a step of obtaining a plurality of semiconductor chips.
In the pre-dicing method, the grooves formed in the semiconductor wafer have a depth shallower than the thickness of the semiconductor wafer. Here, in this step, the semiconductor wafer is thinned by grinding to at least the bottom of the groove, so that the groove becomes a cut penetrating the wafer, and the semiconductor wafer is divided into a plurality of semiconductor chips. Fragmented.

As described above, in the production 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. , back surface grinding can be performed for dividing the semiconductor wafer. As a result, it is possible to effectively suppress adverse effects such as chipping of the end portion of the obtained semiconductor chip, and to improve the yield in manufacturing the semiconductor chip.

In addition, it is preferable to carry out the step (2) in an environment in which the expandable particles do not expand.
For example, when thermally expandable particles are used as the expandable particles, step (2) may be performed under temperature conditions below the expansion start temperature (t) of the thermally expandable particles. is preferably carried out in an environment of 0 to 80° C. (in an environment below the expansion initiation temperature (t) when the expansion initiation temperature (t) is 60 to 80° C.).

<Step (3)>
In the step (3), the expandable particles are expanded to form an 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. It is a process of separating with P.
FIG. 2(c) shows a state in which the expandable particles in the expandable substrate 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 adhered to the hard support 50 at the interface P. Although it is separated, it is preferable that there is no separation between the layers constituting the pressure-sensitive 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 thermally 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 thermally expandable particles to expand the thermally expandable particles.
At this time, the above-mentioned "expansion start temperature (t) or higher temperature" is preferably "expansion start temperature (t) + 10°C" or higher and "expansion start temperature (t) + 60°C" or lower. Temperature (t) + 15°C” or higher and “expansion start temperature (t) + 40°C” or lower are more preferable.

In the production method of the present invention, a pressure-sensitive adhesive sheet having an expandable substrate layer (Y1) containing expandable particles is used, and the expansion of the expandable particles causes the first pressure-sensitive adhesive layer to adhere to the hard support. By forming unevenness on the adhesive surface of (X1), adjustment is made so that separation can occur at the interface P between the hard support and the first adhesive layer (X1).
Therefore, it is possible to suppress contamination of the hard support such that part of the first pressure-sensitive adhesive layer (X1) remains on the surface of the hard support after separation, and it is possible to omit the washing step of the hard support, thereby improving productivity. can improve

<Step (4)>
In step (4), after separation from the hard support in step (3), the back surfaces of the plurality of semiconductor chips opposite to the circuit surface are coated with a base film and an adhesive layer and/or an adhesive layer. It is a step of removing the adhesive sheet from the semiconductor chip after attaching it to the transfer tape provided.
FIG. 3A shows a state in which the adhesive sheet 1a is removed from the semiconductor chips 70 after the back surfaces 72 of the plurality of semiconductor chips 70 are attached to the transfer tape 80. FIG.

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, energy rays are applied to the second pressure-sensitive adhesive layer. The adhesive force of (X2) may be reduced and the adhesive sheet 1a may be removed.
In addition, it is preferable to irradiate the energy beam from the pressure-sensitive adhesive sheet side in order to reduce the adhesive strength of the second pressure-sensitive adhesive layer (X2).
After removing the adhesive sheet 1a, the circuit surfaces 71 of the plurality of semiconductor chips 70 are exposed, and the back surfaces 72 are adhered to the transfer tape 80. FIG.

The transfer tape 80 is an adhesive tape designed to be elongated by being stretched in the MD direction, and is designed to widen the intervals between the plurality of semiconductor chips 70 .
The transfer tape used in one aspect of the present invention has a base film and a pressure-sensitive adhesive layer and/or an adhesive layer. ) can be mentioned.
(1) A transfer tape obtained by laminating a substrate film and an adhesive layer in this order.
(2) A transfer tape obtained by laminating a substrate film and an adhesive layer in this order.
(3) A transfer tape comprising a substrate film, an adhesive layer, and an adhesive layer laminated in this order.

FIG. 3 shows the case where the transfer tape of the above-mentioned (1) mode is used. A state in which back surfaces 72 of a plurality of semiconductor chips 70 are attached is shown.

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

The base film may have a single-layer structure, or may have a multi-layer structure in which two or more layers are laminated.
Moreover, the base film may further contain various additives such as pigments, dyes, flame retardants, plasticizers, antistatic agents, lubricants and fillers.
The thickness of the base film constituting the transfer tape is preferably 20-300 μm, more preferably 30-250 μm, still more preferably 40-200 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 the material for forming the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2). However, it is preferably an energy ray-curable pressure-sensitive adhesive layer formed from the energy ray-curable pressure-sensitive adhesive composition described above, which is suitable as a material for forming the second pressure-sensitive adhesive layer (X2).

When the pressure-sensitive adhesive layer constituting the transfer tape is an energy ray-curable pressure-sensitive adhesive layer, workability in the pick-up step of step (6) is improved.
However, when irradiating the energy ray when removing the adhesive sheet in step (4), the energy ray when removing the adhesive sheet is , it is preferable to irradiate from the adhesive sheet side.

The thickness of the pressure-sensitive adhesive layer constituting the transfer tape is preferably 1-100 μm, more preferably 3-50 μm, still more preferably 5-40 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 binder resins include acrylic resins, polyester resins, urethane resins, acrylic urethane resins, silicone resins, rubber polymers, and phenoxy resins, with acrylic resins being preferred.
The thermosetting component preferably contains an epoxy resin and a thermosetting agent.

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

<Step (5)>
Step (5) is a step of stretching the transfer tape in the MD direction to widen the intervals between the plurality of semiconductor chips.
As shown in FIG. 3B, the transfer tape 80 is stretched in the MD direction to widen the distance between the plurality of semiconductor chips 70, thereby improving pick-up performance in the next process.

<Step (6)>
Step (6) is a step of separating a plurality of semiconductor chips from the transfer tape to obtain semiconductor chips.
FIG. 3(c) shows a state in which a plurality of semiconductor chips 70 are obtained by picking up in this process using the transfer tape of mode (1) above.
Here, when the transfer tape used has an energy ray-curable adhesive layer, irradiation with an energy ray reduces the adhesive strength and improves pick-up properties.
In this case, it is preferable to irradiate the energy beam from the substrate film side.

When the transfer tapes of the above aspects (2) and (3) are used as the transfer tape, the adhesive layer remains adhered to the back surface of the semiconductor chip when picked up in this step, and the semiconductor chip with the adhesive layer is formed. can be obtained and the bonding process can be omitted.

The present invention will be specifically described by the following examples, but the present invention is not limited to the following examples. In addition, the physical property values in the following production examples and examples are values measured by the following methods.

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

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

<Storage Elastic Modulus E′ of Thermally Expandable Base Layer (Y1)>
The thermally expandable base layer (Y1) thus formed was sized 5 mm long×30 mm wide×200 μm thick, and the release material was removed to prepare a test sample.
Using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name “DMAQ800”), the test start temperature is 0 ° C., the test end temperature is 300 ° C., the temperature increase rate is 3 ° C./min, the frequency is 1 Hz, and the amplitude is 20 μm. The storage elastic modulus E' of the test sample was measured at a predetermined temperature under the conditions of .

<Storage shear modulus G′ of the first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2)>
The first pressure-sensitive adhesive layer (X1) and the second pressure-sensitive adhesive layer (X2) formed were cut into a circle with a diameter of 8 mm, the release material was removed, and the thickness was 3 mm. A test sample was obtained. and
Using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300"), the torsional shear method was performed under the conditions of a test start temperature of 0 ° C., a test end temperature of 300 ° C., a temperature increase rate of 3 ° C./min, and a frequency of 1 Hz. measured the storage shear modulus G' of the test sample at a given temperature.

<Probe tack value>
A test sample was prepared by cutting a base material layer to be measured into a square having a side of 10 mm, and leaving the square for 24 hours in an environment of 23° C. and 50% RH (relative humidity).
In an environment of 23 ° C. and 50% RH (relative humidity), using a tacking tester (manufactured by Nihon Tokushu Sokki Co., Ltd., product name "NTS-4800"), the probe tack value on the surface of the test sample is measured according to JIS. Measured according to Z0237:1991.
Specifically, a stainless steel probe with a diameter of 5 mm is brought into contact with the surface of the test sample for 1 second with a contact load of 0.98 N/cm ² , and then the probe is moved at a speed of 10 mm/second to the test sample. The force required to remove it from the surface was measured and the value obtained was taken as the probe tack value for that test sample.

<Measurement of adhesive strength of the second adhesive layer (X2)>
A 50 μm thick PET film (manufactured by Toyobo Co., Ltd., product name “Cosmoshine A4100”) is laminated on the adhesive surface of the second adhesive layer (X2) formed on the release film to form an adhesive sheet with a substrate. bottom.
Then, the release film is removed, and the exposed adhesive surface of the second adhesive layer (X2) is attached to a stainless steel plate (SUS304, No. 360 polishing) as an adherend. ) under the same environment for 24 hours, the adhesive force at 23° C. was measured at a pulling speed of 300 mm/min by a 180° peeling method in accordance with JIS Z0237:2000.

<Young's modulus of hard support>
It was measured at room temperature (25° C.) according to 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, isophorone diisocyanate was added to 100 parts by mass (solid content ratio) of a polycarbonate diol having a mass average molecular weight of 1,000. Then, 160 parts by mass of toluene was added, and the mixture was reacted at 80° C. for 6 hours or more under a nitrogen atmosphere with stirring until the isocyanate group concentration reached the theoretical amount.
Then, a solution obtained by diluting 1.44 parts by mass of 2-hydroxyethyl methacrylate (2-HEMA) (solid content ratio) in 30 parts by mass of toluene was added, and the mixture was further heated at 80°C until the isocyanate groups at both ends disappeared. After reacting for 6 hours, a urethane prepolymer having a mass average molecular weight of 29,000 was obtained.

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

Production Example 2 (Preparation of Adhesive Sheet)
The details of the adhesive resin, additive, thermally expandable particles, substrate and release material used in forming each layer in the preparation of the following adhesive sheet are as follows.
<Adhesive resin>
-Acrylic copolymer (i): 2-ethylhexyl acrylate (2EHA)/2-hydroxyethyl acrylate (HEA) = 80.0/20.0 (mass ratio) having structural units derived from raw material monomers, Mw 600,000 acrylic copolymer.
- Acrylic copolymer (ii): n-butyl acrylate (BA)/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA)/acrylic acid = 86.0/8.0/5.0/1. 0 (mass ratio) acrylic copolymer having Mw of 600,000 and having constituent units derived from raw material monomers.
<Additive>
· Isocyanate cross-linking agent (i): manufactured by Tosoh Corporation, product name "Coronate L", solid content concentration: 75% by 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 ( _D50 ) = 24 µm, 90% particle size ( _D90 ) = 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: product name “SP-PET381031” manufactured by Lintec Corporation, a PET film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.

(1) Formation of the first adhesive layer (X1) To 100 parts by mass of the solid content of the acrylic copolymer (i), which is an adhesive resin, 5.0 parts by mass of the isocyanate cross-linking agent (i) ( solid content ratio), diluted with toluene, and uniformly stirred to prepare a pressure-sensitive adhesive composition having a solid content concentration (active ingredient concentration) of 25% by mass.
Then, the pressure-sensitive adhesive composition is applied to the surface of the release agent layer of the heavy release film to form a coating film, and the coating film is dried at 100 ° C. for 60 seconds to obtain a non-expanding adhesive with a thickness of 5 μm. A first pressure-sensitive adhesive layer (X1), which is an adhesive 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 the second adhesive layer (X2) To 100 parts by mass of the solid content of the acrylic copolymer (ii), which is an adhesive resin, 0.8 parts by mass of the isocyanate cross-linking agent (i) ( solid content ratio), diluted with toluene, and uniformly stirred to prepare a pressure-sensitive adhesive composition having a solid content concentration (active ingredient concentration) of 25% by mass.
Then, the adhesive 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 dried at 100 ° C. for 60 seconds to form a second adhesive with a thickness of 10 μm. A 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 strength of the second adhesive layer (X2) measured based on the above method was 1.0 N/25 mm.
Since it was clear that the second adhesive layer (X2) and the first adhesive layer (X1) had a probe tack value of 50 mN/5 mmφ or more, measurement of the probe tack value was omitted.

(3) Preparation of base material (Y) To 100 parts by mass of the solid content of the acrylic urethane resin obtained in Production Example 1, 6.3 parts by mass of the isocyanate cross-linking agent (i) (solid content ratio), as a catalyst, 1.4 parts by mass of dioctyltin bis(2-ethylhexanoate) (solid content ratio) and the thermally expandable particles (i) were blended, diluted with toluene, stirred uniformly, and the solid content concentration ( Active ingredient concentration) A resin composition having a concentration of 30% by mass was prepared.
The content of the thermally expandable particles (i) was 20% by mass with respect to the total amount (100% by mass) of the active ingredients in the obtained resin composition.
Then, on the surface of a 50 μm thick polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name “Cosmoshine A4100”, probe tack value: 0 mN / 5 mmφ), which is a non-expanding base material, the resin composition A material 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 layer (Y2).

As a sample for measuring the physical property values of the expandable substrate layer (Y1), the resin composition was applied to the surface of the release agent layer of the light release film to form a coating film. C. for 120 seconds to form an expandable substrate layer (Y1) having a thickness of 50 μm in the same manner.
Then, the storage elastic modulus and probe tack value at each temperature of the expandable substrate layer (Y1) were measured based on the above-described measurement method. The measurement results were as follows.
・Storage modulus E′(23) at 23° C.=2.0×10 ⁸ Pa
・Storage modulus E′(208) at 208° C.=5.0×10 ⁵ Pa
・Probe tack value = 0mN/5mmφ
In addition, the storage elastic modulus and probe tack value at each temperature of the PET film, that is, the non-expanding base layer (Y2) were measured. The measurement results were as follows.
・Storage modulus E′(23) at 23° C.=1.0×10 ³ MPa
・Storage modulus E′(208) at 208° C.=0.8×10 ² MPa
・Probe tack value = 0mN/5mmφ

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

In addition, the peel strength (F ₀ ) and (F ₁ ) of the produced pressure-sensitive adhesive sheet was measured according to the following method based on the method described above.
As a result, the peel force (F ₀ ) = 0.23 N/25 mm, the peel force (F ₁ ) = 0 mN/25 mm, and the ratio of the peel force (F ₁ ) to the peel force (F ₀ ) [(F ₁ )/ (F ₀ )] was zero.

<Measurement of peel force (F ₀ )>
After leaving the prepared pressure-sensitive adhesive sheet in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours, the heavy release film of the pressure-sensitive adhesive sheet is removed to expose the first pressure-sensitive adhesive layer (X1). was attached to a silicon wafer.
Next, the end of the silicon wafer with the adhesive sheet attached is fixed to the lower chuck of a universal tensile tester (manufactured by Orientec, product name "Tensilon UTM-4-100"), and the adhesive sheet is fixed with the upper chuck. bottom.
Then, under the same environment as above, peeling at the interface P between the silicon wafer and the first adhesive layer (X1) of the adhesive sheet at a tensile speed of 300 mm / min by a 180 ° peeling method based on JIS Z0237: 2000. The peel force measured at the time of peeling was defined as "peeling force (F ₀ )".

<Measurement of peel force (F ₁ )>
The heavy release film of the produced adhesive sheet is removed, the exposed first adhesive layer (X1) is attached to a silicon wafer, heated at 240 ° C. for 3 minutes, and the heat in the expandable base layer (Y1) The expandable particles were expanded.
After that, 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 adhesive layer (X1) of the adhesive sheet under the above conditions. was defined as "peeling force (F ₁ )".
In the measurement of the peel force (F ₁ ), when trying to fix the adhesive sheet with the upper chuck of the universal tensile tester, the adhesive sheet (I) is completely separated from the silicon wafer and cannot be fixed. , the measurement was terminated, and the peel force (F ₁ ) at that time was set to "0 mN/25 mm".

Production Example 3 (Preparation of transfer tape)
An acrylic copolymer obtained by reacting butyl acrylate/2-hydroxyethyl acrylate = 85/15 (mass ratio), and 80 mol% methacryloyloxyethyl isocyanate (MOI) with respect to 2-hydroxyethyl acrylate. An 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.
Per 100 parts by mass of the solid content of the energy ray-curable acrylic copolymer, 3 parts by mass of 1-hydroxycyclophenyl ketone (manufactured by BASF, product name “Irgacure 184”), which is a photopolymerization initiator, and cross-linking 0.45 parts by mass of a tolylene diisocyanate-based cross-linking agent (manufactured by Tosoh Corporation, product name "Coronate L") was mixed in a solvent to obtain an adhesive composition.
Next, the pressure-sensitive 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 a pressure-sensitive adhesive layer having a thickness of 10 μm.
Then, one side of a polyester-based polyurethane elastomer sheet (manufactured by Seedam Co., Ltd., product name "Higress DUS202", thickness 50 μm) was laminated as a base film to the exposed surface of the pressure-sensitive adhesive layer.
As described above, a transfer tape was obtained by laminating the substrate film, the pressure-sensitive adhesive layer, and the light release film in this order.

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 laminator for back grinding (manufactured by Lintec, device name "RAD-3510F/12"), the heavy release film of the cut adhesive sheet is peeled off, and the first adhesive layer (X1) exposed. The adhesive surface was attached to a hard support (material: silicone, thickness: 725 μm, Young's modulus: 30 GPa). Then, the light release film is also peeled off, and on the adhesive surface of the exposed second adhesive layer (X2), a semiconductor wafer (200 mm in diameter, 725 μm in thickness) having a circuit surface with a circuit formed on one surface The circuit surface of the disc) was attached.
After that, using a stealth laser irradiation device (manufactured by Tokyo Seimitsu Co., Ltd., device name “ML300PlusWH”), stealth laser irradiation is performed from the back surface of the semiconductor wafer opposite to the circuit surface, 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 on which the circuit is not formed is subjected to grinding while being exposed to ultrapure water to divide the semiconductor wafer, and at the same time. Chips were singulated to obtain a plurality of semiconductor chips having a thickness of 20 μm.

<Step (3)>
The temperature in the system containing the hard support, the adhesive sheet, and the plurality of semiconductor chips was set to 240° C., which 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, they could be easily separated collectively at the interface between the hard support and the first pressure-sensitive adhesive layer (X1). At this time, the plurality of semiconductor chips remained attached to the second adhesive layer (X2), and no separation occurred between the layers constituting the adhesive sheet.
After separation from the hard support, no part of the first pressure-sensitive adhesive layer (X1) remained on the surface of the hard support, and no contamination was observed. Therefore, it is considered that the surface of the hard support does not need to be subjected to a new cleaning step.

<Step (4)>
The transfer tape obtained in Production Example 3 was cut into squares of 210 mm×210 mm. At this time, each side of the transfer tape after cutting 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 exposed surface of the pressure-sensitive adhesive layer and the back surfaces of the plurality of semiconductor chips separated from the hard support in step (3) were adhered.
At this time, a group of the plurality of semiconductor chips is attached so as to be positioned in the central portion of the transfer tape, and the dicing line when singulated from the semiconductor wafer is parallel or perpendicular to each side of the transfer tape. affixed so that Then, the group of semiconductor chips was peeled off from the adhesive surface of the second adhesive layer (X2) to remove the adhesive sheet.

<Step (5)>
A transfer tape having a plurality of semiconductor chips attached thereto was placed in an expanding device capable of biaxially stretching. The expanding device has 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, negative direction is -Y-axis direction) which are orthogonal to each other. ) and has holding means for stretching in each direction (ie +X-axis direction, −X-axis direction, +Y-axis direction, −Y-axis direction).
Here, the transfer tape is set in an expanding device with the MD direction of the transfer tape aligned with the X-axis or Y-axis direction, each side of the transfer tape is gripped by the holding means, and then the transfer tape is expanded under the following conditions. It was stretched to widen the intervals between the plurality of semiconductor chips attached on the transfer tape.
・Number of holding means: 5 per side ・Stretching speed: 5 mm/sec
- Stretching distance: Each side was stretched by 60 mm.

<Step (6)>
Using an ultraviolet irradiation device (manufactured by Lintec Co., Ltd., product name “RAD-2000”), ultraviolet rays are irradiated from the base film side of the transfer tape (light amount: 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. Then, it was picked up to obtain a semiconductor chip.
It should be noted that none of the obtained semiconductor chips had chipping or the like at the end.

1a, 1b Adhesive sheet (X1) First adhesive layer (X2) Second adhesive layer (Y) Substrate (Y1) Expandable substrate layer (Y2) Non-expandable substrate layer (Y2-1) First Non-expanding substrate layer (Y2-2) Second non-expanding substrate 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 (10)

a substrate (Y) comprising at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2);
Having a first adhesive layer (X1) and a second adhesive layer (X2) on both sides of the substrate (Y),
A method for producing a semiconductor chip from a semiconductor wafer using an adhesive sheet in which unevenness may occur on the adhesive surface of the first adhesive layer (X1) due to expansion of the expandable particles,
Having the following steps (1) to (3),
The expandable base layer (Y1) and the non-expandable base layer (Y2) constituting the base (Y) are both non-adhesive layers,
The adhesive sheet has a first adhesive layer (X1) on the expandable substrate layer (Y1) side of the substrate (Y), and the non-expandable substrate layer (Y) of the substrate (Y) A method for producing a semiconductor chip having the second adhesive layer (X2) on the Y2) side .
Step (1): A step of attaching the adhesive surface of the first adhesive layer (X1) to a hard support and attaching the adhesive surface of the second adhesive layer (X2) to the surface of a semiconductor wafer.
• Step (2): a step of dividing the semiconductor wafer to obtain a plurality of semiconductor chips.
Step (3): The expandable particles are expanded to adhere the plurality of semiconductor chips on the second pressure-sensitive adhesive layer (X2) to the interface between the hard support and the first pressure-sensitive adhesive layer (X1). Separating with P. a substrate (Y) comprising at least an expandable substrate layer (Y1) containing expandable particles and a non-expandable substrate layer (Y2);
Having a first adhesive layer (X1) and a second adhesive layer (X2) on both sides of the substrate (Y),
A method for producing a semiconductor chip from a semiconductor wafer using an adhesive sheet in which unevenness may occur on the adhesive surface of the first adhesive layer (X1) due to expansion of the expandable particles,
Having the following steps (1) to (3),
The expandable base layer (Y1) and the non-expandable base layer (Y2) constituting the base (Y) are both non-adhesive layers,
The substrate (Y) comprises the expandable substrate layer (Y1) and the non-expandable substrate layer (Y2) provided on the first adhesive layer (X1) side of the expandable substrate layer (Y1). ) [hereinafter referred to as a non-expanding base layer (Y2-1)] and a non-expanding base layer (Y2) provided on the second adhesive layer (X2) side of the expandable base layer (Y1) ) [hereinafter referred to as a non-expanding base layer (Y2-2)],
The storage elastic modulus E′ of the non-expanding base layer (Y2-1) when the expandable particles expand is the storage modulus E′ of the non-expanding base layer (Y2-2) when the expandable particles expand. A method for manufacturing a semiconductor chip having an elastic modulus lower than E'.
Step (1): A step of attaching the adhesive surface of the first adhesive layer (X1) to a hard support and attaching the adhesive surface of the second adhesive layer (X2) to the surface of a 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 non-expanding base layer (Y2) is located farther from the first pressure-sensitive adhesive layer (X1) than the expandable base layer (Y1), and the expandable base layer (Y1 ) and the first pressure-sensitive adhesive layer (X1), the non-expandable base layer (Y2) is not present,
The storage elastic modulus E′ of the non-expanding base layer (Y2) when the expandable particles expand is equal to the storage elastic modulus E of the expandable base layer (Y1) when the expandable particles expand. 2. The method of manufacturing a semiconductor chip according to claim 1 , wherein ' is larger than '. 4. The method for manufacturing a semiconductor chip according to claim 1, wherein in the step ( 3 ), when the expandable particles are expanded, the layers constituting the adhesive sheet are not separated from each other. 5. The method for manufacturing a semiconductor chip according to claim 1, further comprising the following step ( 4 ).
- Step (4): After separation from the hard support in step (3), the back surface of the plurality of semiconductor chips on the side opposite to the circuit surface is covered with a base film and an adhesive layer and/or an adhesive layer. removing the adhesive sheet from the semiconductor chip after attaching it to the transfer tape provided; The method for manufacturing a semiconductor chip according to any one of claims 1 to 5 , wherein the expandable particles are thermally expandable particles having an expansion start temperature (t) of 60 to 270°C. 7. The semiconductor chip according to claim 6 , wherein the thermally expandable particles are expanded by heat treatment between "expansion start temperature (t)+10° C." and "expansion start temperature (t)+60° C." of the thermally expandable particles. manufacturing method. The expandable substrate layer (Y1) is the 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. 8. The method of manufacturing a semiconductor chip according to claim 6 , wherein '(23) is 1.0×10 ⁶ Pa or more. The method for manufacturing a semiconductor chip according to any one of claims 1 to 8 , wherein the non-expandable base layer (Y2) has a volume change rate (%) of less than 2% by volume. The step (2) is a step of grinding the back surface of the semiconductor wafer having the modified region on which the circuit is not formed on the side opposite to the circuit surface, and dividing the semiconductor wafer to obtain a plurality of semiconductor chips. The method for manufacturing a semiconductor chip according to any one of claims 1 to 9 .

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