WO2023017832A1

WO2023017832A1 - Method for manufacturing semiconductor device, and semiconductor wafer with adhesive sheet for semiconductor processing

Info

Publication number: WO2023017832A1
Application number: PCT/JP2022/030513
Authority: WO
Inventors: 康彦垣内
Original assignee: リンテック株式会社
Priority date: 2021-08-13
Filing date: 2022-08-10
Publication date: 2023-02-16
Also published as: KR20240045163A; CN117795650A; TW202316508A

Abstract

The present invention relates to a method for manufacturing a semiconductor device using an adhesive sheet for semiconductor processing having a base material, an intermediate layer, and an adhesive layer in that order, one or more layers selected from the group consisting of the base material, the intermediate layer, and the adhesive layer being a thermal expansion layer containing thermal expansion particles, and the method for manufacturing the semiconductor device including steps 1-4.

Description

Semiconductor device manufacturing method and semiconductor wafer with adhesive sheet for semiconductor processing

The present invention relates to a semiconductor device manufacturing method and a semiconductor wafer with an adhesive sheet for semiconductor processing.

2. Description of the Related Art As information terminal devices are rapidly becoming thinner, smaller, and multi-functional, there is a demand for thinner and higher-density semiconductor devices mounted on these devices.
In the method of manufacturing a semiconductor device, processing such as grinding the back surface of the semiconductor wafer and singulation is performed. This is done with an adhesive sheet attached.

As the adhesive sheet for semiconductor processing, one having an adhesive layer and a substrate supporting the adhesive layer is usually used. The adhesive layer of the adhesive sheet for semiconductor processing is attached to the circuit surface of the semiconductor wafer, and in a state in which the base material is fixed to a support device such as a chuck table, the back side of the semiconductor wafer is ground while the circuit surface is protected, and the semiconductor wafer is singulated. etc. After the predetermined processing, the adhesive sheet for semiconductor processing is peeled off from the surface of the semiconductor wafer.

By the way, the surface of the semiconductor wafer to which the adhesive sheet for semiconductor processing is attached is not necessarily flat, and the adhesive sheet for semiconductor processing may be attached to the surface having protrusions. For example, in recent years, as a technique for miniaturizing a semiconductor device module, a semiconductor wafer having a plurality of bumps having a height of about several tens to several hundreds of μm formed on the circuit surface (hereinafter also referred to as a “bumped wafer”). A flip-chip bonding technique has been put into practical use, in which these bumps are directly bonded to a wiring substrate after back-grinding and individualizing the bumps.

When the adhesive sheet for semiconductor processing is attached to the bump-formed surface of the wafer with bumps, the portion covering the bumps of the adhesive sheet for semiconductor processing swells more than the other portion, and the surface of the base material opposite to the attachment surface is projected. part may occur. If the back surface of the semiconductor wafer is ground with the surface having the protrusions fixed, the thickness uniformity of the semiconductor wafer after back grinding is poor.

In order to alleviate the above problem, the adhesive sheet for semiconductor processing applied to the surface having protrusions is sometimes provided with an intermediate layer for embedding the protrusions.
Patent Document 1 discloses, as a temporary fixing tape for grinding a substrate, a temporary fixing tape comprising a support base and an adhesive layer laminated on one surface of the support base, wherein the support base The material has a first layer that supports the substrate, and a second layer that is positioned between the first layer and the adhesive layer and has cushioning properties, and has projections on at least one surface. When the substrate having the surface of is bonded to the adhesive layer, the tip of the protrusion penetrates the adhesive layer and is located in the second layer, and the tip of the protrusion penetrates the adhesive layer and is located in the second layer, When the adhesive force of the adhesive layer is F1 [N/25 mm] and the adhesive force of the second layer is F2 [N/25 mm], a temporary fixing tape that satisfies the relationship of F1>F2. is disclosed.

JP 2020-77799 A

According to the temporary fixing tape of Patent Document 1, the projections provided on the surface of the substrate penetrate the adhesive layer and are positioned within the second layer corresponding to the intermediate layer. As a result, it is possible to apply a uniform pressing force over the entire surface of the substrate, so that the substrate can be made thin with a uniform thickness.

By forming an intermediate layer on the adhesive sheet for semiconductor processing and burying the projections of the semiconductor wafer with the intermediate layer as in the technique of Patent Document 1, the protrusions on the surface of the adhesive sheet for semiconductor processing on the substrate side are formed. It tends to be possible to suppress the occurrence.
However, for example, when the height of the protrusion is large, or when the area of the protrusion is large, it may be difficult to suppress the occurrence of protrusions only by the method of embedding the protrusion in the intermediate layer. In addition, if the embedding property is enhanced, the mechanical strength of the intermediate layer is lowered, and the protection around the protrusion may become insufficient, and part of the intermediate layer may adhere to the periphery of the protrusion after peeling. Therefore, there is a limit to suppressing the occurrence of protrusions in the pressure-sensitive adhesive sheet for semiconductor processing applied to a semiconductor wafer having protrusions only by the method of embedding the protrusions in the intermediate layer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is intended to reduce the difference in height between convex portions and non-convex portions generated in a semiconductor processing pressure-sensitive adhesive sheet attached to a semiconductor wafer having protrusions. It is an object of the present invention to provide a semiconductor device manufacturing method capable of enhancing processing accuracy, and a semiconductor wafer with an adhesive sheet for semiconductor processing that can be used in this manufacturing method.

As a result of intensive studies, the present inventors have a substrate, an intermediate layer, and an adhesive layer in this order, and are selected from the group consisting of the substrate, the intermediate layer, and the adhesive layer. The above problems are solved by using a semiconductor processing pressure-sensitive adhesive sheet in which one or more layers are thermally expandable layers containing thermally expandable particles, and by partially expanding the semiconductor processing pressure-sensitive adhesive sheet by a specific method. After discovering that it is possible, the following invention was completed.

That is, the present invention relates to the following [1] to [14].
[1] having a substrate, an intermediate layer, and an adhesive layer in this order, wherein one or more layers selected from the group consisting of the substrate, the intermediate layer, and the adhesive layer are thermally expandable A semiconductor device manufacturing method using a semiconductor processing pressure-sensitive adhesive sheet that is a thermally expandable layer containing particles, the method comprising the following steps 1 to 4.
Step 1: Attaching the adhesive sheet for semiconductor processing to the surface (Wα) having the protrusions of the semiconductor wafer (W) having the protrusions using the adhesive layer as the attachment surface Step 2: The attached semiconductor On the surface (Sα) on the base material side of the pressure-sensitive adhesive sheet for processing, among the convex portions caused by the convex portions and the non-convex portions that are portions other than the convex portions, the upper surface of the convex portions Step 3: contacting the coolant, by heating the semiconductor wafer (W) having the protrusions to the expansion start temperature (t) of the thermally expandable particles or higher while contacting the coolant, The pressure-sensitive adhesive sheet for semiconductor processing is heated from the side of the semiconductor wafer (W) having the protrusions, and the cooling effect of the coolant suppresses the expansion of the portion of the pressure-sensitive adhesive sheet for semiconductor processing having the protrusions as a surface. while expanding the portion having the non-convex portion as a surface to reduce the height difference between the convex portion and the non-convex portion Step 4: With the base material of the pressure-sensitive adhesive sheet for semiconductor processing fixed, [2] The method of manufacturing a semiconductor device according to [1] above, wherein the heat conductivity of the coolant at 20° C. is 50 W/m·K or more. .
[3] The method of manufacturing a semiconductor device according to [1] or [2] above, wherein the coolant is metal.
[4] The method of manufacturing a semiconductor device according to any one of [1] to [3] above, wherein the thickness of the coolant is 100 times or more the thickness of the thermal expansion layer.
[5] The method of manufacturing a semiconductor device according to any one of [1] to [4] above, wherein the intermediate layer has a thickness of 10 to 500 μm.
[6] The method for manufacturing a semiconductor device according to any one of [1] to [5] above, wherein the pressure-sensitive adhesive layer has a thickness of 1 to 80 μm.
[7] Any of the above [1] to [6], wherein the content of the thermally expandable particles is 0.05 to 25% by mass with respect to the total mass (100% by mass) of the thermally expandable layer. 2. A method of manufacturing a semiconductor device according to claim 1.
[8] The method for manufacturing a semiconductor device according to any one of [1] to [7] above, wherein the thermally expandable particles have an expansion start temperature (t) of 50°C or higher and lower than 125°C.
[9] The method of manufacturing a semiconductor device according to any one of [1] to [8] above, wherein the intermediate layer is the thermally expandable layer.
[10] The heating of the adhesive sheet for semiconductor processing in the step 3 is performed by heating the surface (Wβ) opposite to the surface (Wα) of the semiconductor wafer (W) having the protrusions. A method for manufacturing a semiconductor device according to any one of [1] to [9].
[11] The method of manufacturing a semiconductor device according to any one of [1] to [10] above, wherein the protrusion has a height of 10 to 500 μm.
[12] The method of manufacturing a semiconductor device according to any one of [1] to [11] above, wherein the semiconductor wafer (W) having protrusions is a semiconductor wafer having bumps as the protrusions.
[13] The method for manufacturing a semiconductor device according to [12] above, wherein the processing in the step 4 is back grinding of the semiconductor wafer having the bumps.
[14] A semiconductor processing adhesive sheet having a base material, an intermediate layer, and an adhesive layer in this order has the adhesive layer as an attachment surface, and the protrusions of the semiconductor wafer (W) having protrusions. A semiconductor wafer with an adhesive sheet for semiconductor processing, which is attached to a surface (Wα) having
The adhesive sheet for semiconductor processing, in plan view,
a void-containing or void-free region (a);
a region (b) having a higher void volume content than the region (a) and a thickness greater than the region (a);
A semiconductor wafer with an adhesive sheet for semiconductor processing, wherein the substrate-side surface (Sα) is flattened by a difference in thickness between the region (a) and the region (b).

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to reduce the height difference between convex portions and non-convex portions generated in a semiconductor processing pressure-sensitive adhesive sheet attached to a semiconductor wafer having protrusions, thereby manufacturing a semiconductor device capable of enhancing processing accuracy of the semiconductor wafer. It is possible to provide a method and a semiconductor wafer with an adhesive sheet for semiconductor processing that can be used in this manufacturing method.

FIG. 2 is a cross-sectional view showing an example of the configuration of the pressure-sensitive adhesive sheet for semiconductor processing; It is a top view for demonstrating the semiconductor wafer (W) which has a protrusion part. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention. It is a sectional view explaining an example of a process of a manufacturing method of a semiconductor device of the present invention.

In this specification, the lower and upper limits described stepwise for preferred numerical ranges 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

In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.

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

In this specification, whether a "layer" is a "non-thermally expandable layer" or a "thermally expandable layer" is determined as follows.
When the layer to be judged contains thermally expandable particles, the layer is heat-treated for 3 minutes at the expansion start temperature (t) of the thermally expandable particles. If the volume change rate calculated from the following formula is less than 5%, the layer is determined to be a "non-thermally expandable layer", and if it is 5% or more, the layer is a "thermally expandable layer". judge there is.
・Volume change rate (%) = {(volume of the layer after heat treatment - volume of the layer before heat treatment) / volume of the layer before heat treatment} x 100
A layer containing no thermally expandable particles is referred to as a "non-thermally expandable layer".
In this specification, when the "layer" is a non-thermally expandable layer, the volume change rate (%) of the non-thermally expandable layer calculated from the above formula is less than 5%, preferably less than 2%. , more preferably less than 1%, more preferably less than 0.1%, even more preferably less than 0.01%.
Further, in the present specification, when the "layer" is a non-thermally expandable layer, the non-thermally expandable layer preferably does not contain thermally expandable particles. It may contain expandable particles. When the non-thermally expandable layer contains thermally expandable particles, the content is preferably as small as possible, preferably less than 3% by mass, more preferably less than 3% by mass, based on the total mass (100% by mass) of the non-thermally expandable layer. is less than 1% by weight, more preferably less than 0.1% by weight, even more preferably less than 0.01% by weight, and even more preferably less than 0.001% by weight.

In this specification, the "circuit surface" of the semiconductor wafer refers to the surface on which the circuits are formed, and the "back surface" of the semiconductor wafer refers to the surface on which the circuits are not formed.

In this specification, "semiconductor device" refers to all devices that can function by utilizing semiconductor characteristics. For example, a wafer comprising integrated circuits, a thinned wafer comprising integrated circuits, a chip comprising integrated circuits, a thinned chip comprising integrated circuits, electronic components comprising these chips, and electronic equipment comprising such electronic components and the like.

In this specification, the thickness of each layer is the thickness at 23°C and means the value measured by the method described in Examples.

The mechanism of action described in this specification is speculation, and does not limit the mechanism of the effects of the present invention.

[Method for manufacturing a semiconductor device]
A method for manufacturing a semiconductor device according to one aspect of the present invention includes a substrate, an intermediate layer, and an adhesive layer in this order, and is selected from the group consisting of the substrate, the intermediate layer, and the adhesive layer. A method for manufacturing a semiconductor device using a semiconductor processing pressure-sensitive adhesive sheet in which one or more layers are thermally expandable layers containing thermally expandable particles, comprising the following steps 1 to 4: be.
Step 1: Attaching the adhesive sheet for semiconductor processing to the surface (Wα) having the protrusions of the semiconductor wafer (W) having the protrusions using the adhesive layer as the attachment surface Step 2: The attached semiconductor On the surface (Sα) on the base material side of the pressure-sensitive adhesive sheet for processing, among the convex portions caused by the convex portions and the non-convex portions that are portions other than the convex portions, the upper surface of the convex portions Step 3: contacting the coolant, by heating the semiconductor wafer (W) having the protrusions to the expansion start temperature (t) of the thermally expandable particles or higher while contacting the coolant, The pressure-sensitive adhesive sheet for semiconductor processing is heated from the side of the semiconductor wafer (W) having the protrusions, and the cooling effect of the coolant suppresses the expansion of the portion of the pressure-sensitive adhesive sheet for semiconductor processing having the protrusions as a surface. while expanding the portion having the non-convex portion as a surface to reduce the height difference between the convex portion and the non-convex portion Step 4: With the base material of the pressure-sensitive adhesive sheet for semiconductor processing fixed, A step of processing the semiconductor wafer (W) having the projections

Hereinafter, the semiconductor processing adhesive sheet used in the method for manufacturing a semiconductor device of one embodiment of the present invention will be described first, and then each step included in the method for manufacturing a semiconductor device of one embodiment of the present invention will be described in detail.

<Adhesive sheet for semiconductor processing>
A pressure-sensitive adhesive sheet for semiconductor processing according to one embodiment of the present invention (hereinafter also simply referred to as "pressure-sensitive adhesive sheet") is a pressure-sensitive adhesive sheet having a substrate, an intermediate layer, and an adhesive layer in this order.
The pressure-sensitive adhesive sheet of one embodiment of the present invention is attached to the surface (Wα) having projections of the semiconductor wafer (W), and is used to perform predetermined processing on the semiconductor wafer (W) while protecting the surface. Then, after the semiconductor wafer (W) is subjected to predetermined processing, the adhesive sheet of one embodiment of the present invention is peeled off.

FIG. 1(a) shows a pressure-sensitive adhesive sheet 10a in which a substrate 1, an intermediate layer 2 and a pressure-sensitive adhesive layer 3 are laminated in this order, which is a pressure-sensitive adhesive sheet of one embodiment of the present invention.
The pressure-sensitive adhesive sheet of one embodiment of the present invention may have only a substrate, an intermediate layer and a pressure-sensitive adhesive layer like the pressure-sensitive adhesive sheet 10a, but may have other layers as necessary. good too. Other layers include, for example, a release sheet provided on the surface of the pressure-sensitive adhesive layer opposite to the intermediate layer.
FIG. 1(b) shows a pressure-sensitive adhesive sheet 10b of one embodiment of the present invention having a release sheet 4 as another layer. The release sheet 4 is laminated on the adhesive surface of the adhesive layer 3 in the adhesive sheet 10b.

Next, preferred aspects of each layer included in the pressure-sensitive adhesive sheet of one aspect of the present invention will be described.

(Thermal expansion layer)
In one aspect of the pressure-sensitive adhesive sheet of the present invention, one or more layers selected from the group consisting of a substrate, an intermediate layer, and a pressure-sensitive adhesive layer are thermally expandable layers containing thermally expandable particles.
The pressure-sensitive adhesive sheet of one aspect of the present invention may have two or more thermally expandable layers, but preferably has only one layer. When the pressure-sensitive adhesive sheet of one embodiment of the present invention has two or more thermally expandable layers, it may have a layer other than the thermally expandable layer between the thermally expandable layers. It does not have to have any layers other than the thermally expandable layer.
The pressure-sensitive adhesive sheet of one embodiment of the present invention preferably has an embodiment in which the intermediate layer is a thermally expandable layer, and an embodiment in which the intermediate layer is a thermally expandable layer and the substrate and the adhesive layer are non-thermally expandable layers. more preferred. When the intermediate layer is a heat-expandable layer and the substrate and the pressure-sensitive adhesive layer are non-heat-expandable layers, it is difficult for unevenness caused by the heat-expandable particles after thermal expansion to appear on the surface of the pressure-sensitive adhesive layer or the substrate. As a result, the adhesiveness to the semiconductor wafer (W) or the holding property by a support device such as a chuck table tends to be improved.

The thickness of the thermally expandable layer is not particularly limited, and may be appropriately determined according to which layer is the thermally expandable layer among the layers included in the pressure-sensitive adhesive sheet of one embodiment of the present invention.
In this specification, simply referring to the "thickness of the thermally expandable layer" means the total thickness of all the thermally expandable layers included in the pressure-sensitive adhesive sheet of one embodiment of the present invention. For example, when only one of the base material, the intermediate layer, and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention is a thermally expandable layer, the thickness of the layer is the thickness of the thermally expandable layer. . Further, when two or more of the base material, the intermediate layer and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention are thermally expandable layers, the total thickness of the two or more layers is the thickness of the thermally expandable layer. It is.

[Thermal expandable particles]
The thermally expandable particles may be particles that expand when heated.
The thermally expandable particles may be used singly or in combination of two or more.

The expansion start temperature (t) of the thermally expandable particles is preferably 50° C. or more and less than 125° C., more preferably 55 to 120° C., still more preferably 60 to 115° C., still more preferably 70 to 110° C., still more preferably is 75-105°C. When the expansion start temperature (t) of the thermally expandable particles is 50°C or higher, unintended expansion tends to be suppressed. Moreover, when the expansion start temperature (t) of the thermally expandable particles is less than 125° C., the heating temperature at the time of heat peeling can be kept low.
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.
The thermoplastic resin constituting the outer shell of the microencapsulated foaming agent includes, for example, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, or structural units contained in these thermoplastic resins. Examples thereof include copolymers obtained by polymerizing two or more of the monomers to be formed.

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

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

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

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

The content of the thermally expandable particles is preferably 0.05 to 25% by mass, more preferably 0.1 to 15% by mass, still more preferably 0, based on the total mass (100% by mass) of the thermally expandable layer. .2 to 10% by weight, more preferably 0.3 to 5% by weight. When the content of the thermally expandable particles is 0.05% by mass or more, the protrusions of the adhesive sheet caused by the protrusions of the semiconductor wafer (W) tend to be flattened easily. Further, when the content of the thermally expandable particles is 25% by mass or less, the unevenness of the thermally expandable particles before thermal expansion becomes difficult to appear on the surface of the adhesive layer or the base material, and the semiconductor wafer (W) and the There is a tendency that adhesion or retention by a support device such as a chuck table tends to be improved.

(Base material)
The substrate used in one aspect of the present invention is not particularly limited as long as it is made of a material capable of supporting the semiconductor wafer (W).

The substrate is preferably a non-adhesive substrate.
The probe tack value on the surface of the substrate is usually less than 50 mN/5 mmφ, preferably less than 30 mN/5 mmφ, more preferably less than 10 mN/5 mmφ, still more preferably less than 5 mN/5 mmφ.
In addition, in this specification, the probe tack value on the surface of the substrate means the value measured by the following method.
<Probe tack value>
After cutting the base material to be measured into a square with a side of 10 mm, a test sample was left to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours. ), using a tacking tester (product name “NTS-4800” manufactured by Nippon Tokushu Sokki Co., Ltd.), the probe tack value on the surface of the test sample is measured in accordance with JIS Z0237: 1991. be able to. Specifically, a stainless steel probe with a diameter of 5 mm 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 can be measured and the resulting value taken as the probe tack value for that test sample.

Examples of materials for the substrate include resins, metals, paper materials, 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; polyethylene terephthalate, Polyester resins such as polybutylene terephthalate and polyethylene naphthalate; Polystyrene; Acrylonitrile-butadiene-styrene copolymer; Cellulose triacetate; Polycarbonate; ketone; polyether sulfone; polyphenylene sulfide; polyimide-based resin such as polyetherimide and polyimide; polyamide-based resin;
Examples of metals include aluminum, tin, chromium, and titanium.
Examples of the paper material include thin paper, medium quality paper, fine paper, impregnated paper, coated paper, art paper, parchment paper, and glassine paper.
Among these, polyester-based resins such as polyethylene terephthalate (hereinafter also referred to as “PET”), polybutylene terephthalate, and polyethylene naphthalate are preferred.

These forming materials may be composed of one type, or two or more types may be used in combination.
Examples of substrates using two or more kinds of forming materials include those obtained by laminating a paper material with a thermoplastic resin such as polyethylene, a resin film or sheet containing a resin, and a metal film formed on the surface of the sheet. . As a method for forming the metal layer, for example, a method of depositing the above metal by a PVD method such as vacuum deposition, sputtering, or ion plating, or a method of attaching a metal foil made of the above metal using a general adhesive. and the like.

In addition, from the viewpoint of improving the interlayer adhesion between the base material and other layers to be laminated, when the base material contains a resin, the surface of the base material is treated by an oxidation method, a roughening method, etc., and an easy adhesion Treatment or primer treatment may be applied.

The base material may contain base material additives as necessary. Examples of base material additives include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, colorants, and the like. One of these base material additives may be used alone, or two or more thereof may be used in combination.

When the substrate is a thermally expandable layer containing thermally expandable particles (hereinafter also referred to as "thermally expandable substrate"), the substrate is treated with a substrate composition containing a resin and thermally expandable particles. can be formed.
Preferred aspects of the type and content of the thermally expandable particles are the same as the preferred aspects of the type and content of the thermally expandable particles in the description of the thermally expandable layer above.

Among the types of resins described above, urethane-based resins and olefin-based resins are preferable, urethane-based resins are more preferable, and acrylic-modified polyurethanes are even more preferable.
When the base composition contains an acrylic-modified polyurethane, the base composition further contains an energy ray-polymerizable monomer, a photopolymerization initiator, etc., in addition to the acrylic-modified polyurethane and the thermally expandable particles, A non-solvent resin composition containing no solvent may also be used.
Although the solventless resin composition does not contain a solvent, the energy ray-polymerizable monomer contributes to the improvement of plasticity. By irradiating the solvent-free resin composition with an energy ray, the acrylic-modified polyurethane, the energy ray-polymerizable monomer, and the like are polymerized to form a thermally expandable base material.
Examples of the energy ray-polymerizable monomer and photopolymerization initiator include the same polymerizable monomer and photopolymerization initiator that may be contained in the intermediate layer composition described below.

The substrate may be a substrate laminate in which a thermally expandable substrate and a substrate that is a non-thermally expandable layer (hereinafter also referred to as “non-thermally expandable substrate”) are laminated.
When the substrate is the substrate laminate described above, the thermally expandable substrate may be arranged on the intermediate layer side and the non-thermally expandable substrate may be arranged on the side opposite to the intermediate layer. The substrate may be arranged on the intermediate layer side, and the thermally expandable substrate may be arranged on the side opposite to the intermediate layer.
When the non-thermally expansible base material is arranged on the side opposite to the intermediate layer, it becomes difficult for the unevenness due to the expanded thermally expandable particles to appear on the surface opposite to the intermediate layer, so that it is held by a support device such as a chuck table. tend to have good properties. On the other hand, when the non-thermally expandable base material is arranged on the intermediate layer side, the unintentional expansion of the thermally expandable base material due to frictional heat or the like during processing of the adherend (W) is suppressed. tend to be easy.

The thickness of the substrate is preferably 5-500 μm, more preferably 15-300 μm, still more preferably 20-200 μm. When the thickness of the substrate is 5 μm or more, the deformation resistance of the pressure-sensitive adhesive sheet tends to be easily improved. Moreover, when the thickness of the base material is 500 μm or less, the handleability of the pressure-sensitive adhesive sheet tends to be improved.
In addition, the thickness of a base material means the thickness of the whole base material. For example, the thickness of a base material composed of multiple layers means the total thickness of all layers constituting the base material.

(middle layer)
The intermediate layer is a layer arranged between the substrate and the pressure-sensitive adhesive layer.
Although the composition of the intermediate layer is not particularly limited, the intermediate layer is preferably formed from an intermediate layer composition containing a resin.

Examples of resins contained in the intermediate layer composition include urethane (meth)acrylates and acrylic resins.

[Urethane (meth)acrylate]
A urethane (meth)acrylate is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of being polymerized by irradiation with energy rays. When the intermediate layer composition contains urethane (meth)acrylate, the resulting intermediate layer tends to have good flexibility.
Urethane (meth)acrylates may be used alone or in combination of two or more.

The urethane (meth)acrylate may be a monofunctional urethane (meth)acrylate or a polyfunctional urethane (meth)acrylate. (Meth)acrylate is more preferred.

The weight average molecular weight (Mw) of the urethane (meth)acrylate is preferably 10,000 to 100,000, more preferably 20,000 to 90,000, still more preferably 25,000 to 70,000, still more preferably 30,000 to 60,000.

A urethane (meth)acrylate can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyvalent isocyanate compound with a (meth)acrylate having a hydroxy group.

Examples of polyol compounds include alkylene-type polyols, ether-type polyols, ester-type polyols, esteramide-type polyols, ester/ether-type polyols, and carbonate-type polyols.
A polyol compound may be used individually by 1 type, and may use 2 or more types together.

Examples of polyvalent isocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. 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.
Polyvalent isocyanate may be used individually by 1 type, and may use 2 or more types together.

(Meth)acrylates having a hydroxy group include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3 -hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and the like.
The (meth)acrylates having a hydroxy group may be used alone or in combination of two or more.

The content of urethane (meth)acrylate in the intermediate layer composition is preferably 20 to 90% by mass, more preferably 35 to 80% by mass, based on the total amount (100% by mass) of active ingredients in the intermediate layer composition. % by mass, more preferably 50 to 70% by mass.

[Acrylic resin]
Examples of the acrylic resin that can be used as the resin contained in the intermediate layer composition include the same acrylic resins that can be used as the adhesive resin of the adhesive layer described below.

The intermediate layer composition more preferably contains the urethane (meth)acrylate and a polymerizable monomer other than the urethane (meth)acrylate.

[Polymerizable monomer]
The polymerizable monomer is preferably a polymerizable compound other than urethane (meth)acrylate and is polymerizable with other components by irradiation with energy rays. Specifically, the polymerizable monomer is preferably a compound having at least one (meth)acryloyl group.
The polymerizable monomers may be used singly or in combination of two or more.

Examples of polymerizable monomers include (meth)acrylates having an alkyl group having 1 to 30 carbon atoms; (meth)acrylates having a functional group such as a hydroxyl group, an amide group, an amino group, and an epoxy group; (Meth)acrylates having a cyclic structure; (meth)acrylates having an aromatic structure; (meth)acrylates having a heterocyclic structure; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone , vinyl compounds such as N-vinylcaprolactam; allyl compounds such as allyl glycidyl ether;

(Meth)acrylates having an alkyl group having 1 to 30 carbon atoms include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (Meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate , nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, eicosyl (Meth)acrylate and the like.
The (meth)acrylate having an alkyl group having 1 to 30 carbon atoms preferably has 4 to 24 carbon atoms, more preferably 8 to 18 carbon atoms, and still more preferably 10 to 14 carbon atoms.

(Meth)acrylates having a functional group include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3 -Hydroxy group-containing (meth)acrylates such as hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N - amide group-containing compounds such as methylol (meth)acrylamide, N-methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide; primary amino group-containing (meth)acrylate , secondary amino group-containing (meth)acrylates, tertiary amino group-containing (meth)acrylates; glycidyl (meth)acrylate, methylglycidyl (meth)acrylate and the like.

(Meth)acrylates having an alicyclic structure include, for example, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, ) acrylate, trimethylcyclohexyl (meth)acrylate, adamantane (meth)acrylate, and the like. Among these, isobornyl (meth)acrylate and trimethylcyclohexyl (meth)acrylate are preferred.

(Meth)acrylates having an aromatic structure include, for example, phenylhydroxypropyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate and the like.
(Meth)acrylates having a heterocyclic structure include, for example, tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate.

Among the above polymerizable monomer options, the intermediate layer composition should contain a (meth)acrylate having an alkyl group having 1 to 30 carbon atoms and a (meth)acrylate having an alicyclic structure. is preferred.
The content of the (meth)acrylate having an alkyl group having 1 to 30 carbon atoms in the intermediate layer composition is preferably 1 with respect to the total amount (100% by mass) of the active ingredients in the intermediate layer composition. to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass.
The content of the (meth)acrylate having an alicyclic structure in the intermediate layer composition is preferably 5 to 50% by mass, more than It is preferably 10 to 40% by mass, more preferably 15 to 30% by mass.

The total content of the polymerizable monomers in the intermediate layer composition is preferably 8 to 70% by mass, more preferably 15 to 70% by mass, based on the total amount (100% by mass) of the active ingredients in the intermediate layer composition. 50% by mass, more preferably 30 to 40% by mass.

The ratio of the urethane (meth)acrylate content to the polymerizable monomer content (urethane (meth)acrylate/polymerizable monomer) in the intermediate layer composition is preferably 20/80 to 90/10, more preferably 40/60 to 80/20, still more preferably 60/40 to 70/30.

[Photopolymerization initiator]
The intermediate layer composition preferably further contains a photopolymerization initiator together with the urethane (meth)acrylate and the polymerizable monomer. By including a photopolymerization initiator in the intermediate layer composition, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.
A photoinitiator may be used individually by 1 type, and may use 2 or more types together.

Examples of photopolymerization initiators include photopolymerization initiators such as benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. .
More specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, 2,2 -dimethoxy-1,2-diphenylethan-1-one and the like.

The content of the photopolymerization initiator in the intermediate layer composition is preferably 0.05 to 15 parts by mass, more preferably 0 parts by mass, with respect to the total of 100 parts by mass of the urethane (meth)acrylate and the polymerizable monomer. .5 to 10 parts by mass, more preferably 1 to 5 parts by mass.

[Chain transfer agent]
The intermediate layer composition preferably further contains a chain transfer agent together with the urethane (meth)acrylate and the polymerizable monomer. By containing the chain transfer agent in the composition for the intermediate layer, it becomes possible for components with relatively short molecular chains to remain even after curing, and the polymer after curing has flexibility.
A chain transfer agent may be used individually by 1 type, and may use 2 or more types together.

Examples of chain transfer agents include thiol group-containing compounds. Examples of thiol group-containing compounds include nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, and 1,2,3-propanetrithiol. , tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakisthioglucolate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyric rate), 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione and the like. Among these, pentaerythritol tetrakis(3-mercaptobutyrate) is preferred.

The content of the chain transfer agent in the intermediate layer composition is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 10 parts by mass, based on the total of 100 parts by mass of the urethane (meth)acrylate and the polymerizable monomer. 3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass.

[Thermal expandable particles]
When the intermediate layer is a thermally expandable layer containing thermally expandable particles, the intermediate layer can be formed from an intermediate layer composition containing thermally expandable particles. Preferred aspects of the type and content of the thermally expandable particles are the same as the preferred aspects of the type and content of the thermally expandable particles in the description of the thermally expandable layer above.

[Additive for intermediate layer]
The intermediate layer composition may contain intermediate layer additives in addition to the components described above, as long as the effects of the present invention are not impaired. Examples of additives for the intermediate layer include antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, tackifiers and the like.
These intermediate layer additives may be used singly or in combination of two or more.
When the intermediate layer composition contains these intermediate layer additives, the content of each intermediate layer additive is independently 100 mass in total of the urethane (meth)acrylate and the polymerizable monomer. 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass.

The intermediate layer composition used in one aspect of the present invention may contain a solvent as long as the effects of the present invention are not impaired. It is preferably a solvent-free resin composition that does not contain.
Although the solvent-free resin composition does not contain a solvent, the polymerizable monomer mentioned above contributes to the improvement of the plasticity of the resin.
By irradiating the solvent-free resin composition with energy rays, the urethane (meth)acrylate, the polymerizable monomer, etc. are polymerized to form the intermediate layer.

[Thickness of intermediate layer]
In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the thickness of the intermediate layer is preferably 10-500 μm, more preferably 20-350 μm, still more preferably 30-200 μm. When the thickness of the intermediate layer is 10 μm or more, it tends to be easy to embed the projections of the semiconductor wafer (W). In addition, when the thickness of the intermediate layer is 500 μm or less, the handleability of the pressure-sensitive adhesive sheet tends to be improved.
The thickness of the intermediate layer means the thickness of the entire intermediate layer. For example, the thickness of an intermediate layer composed of multiple layers means the total thickness of all the layers that make up the intermediate layer.

(Adhesive layer)
The pressure-sensitive adhesive layer is a layer provided on the side of the intermediate layer opposite to the base material, and is a layer that is attached to the surface (Wα) having protrusions of the semiconductor wafer (W).

The adhesive layer is preferably a layer having energy ray curability. Since the adhesive layer has energy ray curability, the surface of the semiconductor wafer (W) can be well protected with sufficient adhesiveness before energy ray curing, and the peeling force is reduced after energy ray curing. and can be easily separated from the semiconductor wafer (W).

The adhesive layer can be formed from an adhesive composition containing an adhesive resin.
Examples of the pressure-sensitive adhesive composition include the following X-type pressure-sensitive adhesive composition, Y-type pressure-sensitive adhesive composition, and XY-type pressure-sensitive adhesive composition.
X-type adhesive composition: Energy ray-curable containing a non-energy ray-curable adhesive resin (hereinafter also referred to as “adhesive resin I”) and an energy ray-curable compound other than the adhesive resin Adhesive composition Y-type adhesive composition: an energy ray-curable adhesive resin in which an unsaturated group is introduced into the side chain of a non-energy ray-curable adhesive resin (hereinafter, also referred to as "adhesive resin II" ) and does not contain an energy ray-curable compound other than the adhesive resin XY-type adhesive composition: the energy ray-curable adhesive resin II and other than the adhesive resin and an energy ray-curable pressure-sensitive adhesive composition containing: and an energy ray-curable pressure-sensitive adhesive composition of XY type.

Next, each component constituting the pressure-sensitive adhesive layer will be described in more detail.
In the following description, "tacky resin" is used as a term indicating one or both of tacky resin I and tacky resin II.

The adhesive resin may be an adhesive resin having no functional group, but is preferably an adhesive resin having a functional group. By having a functional group, the adhesive resin can obtain, for example, reactivity with a cross-linking agent and energy ray curability, which will be described later.
Examples of functional groups possessed by the adhesive resin include unsaturated groups having energy beam polymerizability such as (meth)acryloyl groups, vinyl groups, and allyl groups; hydroxy groups, carboxy groups, amino groups, epoxy groups, and the like. . Among these, a (meth)acryloyl group and a hydroxy group are preferred. The adhesive resin may have one type of functional group, or may have two or more types of functional groups.

Examples of adhesive resins include acrylic resins, urethane resins, rubber resins, and silicone resins. Among these, acrylic resins are preferable.

[Acrylic resin]
The acrylic resin is not particularly limited as long as it is a polymer containing an acrylic monomer as a monomer component, but preferably contains a structural unit derived from an alkyl (meth)acrylate.
Examples of alkyl (meth)acrylates include alkyl (meth)acrylates in which the alkyl group has 1 to 20 carbon atoms.
The alkyl group of the alkyl (meth)acrylate may be linear or branched.

From the viewpoint of further improving the adhesive strength of the adhesive layer, the acrylic resin preferably contains a structural unit derived from an alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms.
The structural unit derived from the alkyl (meth)acrylate having 4 or more carbon atoms in the alkyl group contained in the acrylic resin may be one type alone or two or more types.
The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate having 4 or more carbon atoms in the alkyl group is preferably 4 to 12, more preferably 4 to 8, and still more preferably 4 to 6.
Examples of alkyl (meth)acrylates in which the alkyl group has 4 or more carbon atoms include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl ( meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate and the like. Among these, 2-ethylhexyl (meth)acrylate is preferred, and 2-ethylhexyl acrylate is more preferred.
The content of the alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms is preferable among the structural units derived from acrylic monomers constituting the acrylic resin, from the viewpoint of further improving the adhesive strength of the pressure-sensitive adhesive layer. is 30 to 90% by mass, more preferably 40 to 80% by mass, and still more preferably 50 to 70% by mass.

From the viewpoint of improving the elastic modulus and adhesive properties of the pressure-sensitive adhesive layer, the acrylic resin has a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms, and an alkyl group having a carbon number of 4 or more. It preferably contains structural units derived from 1 to 3 alkyl (meth)acrylates.
The structural unit derived from the alkyl (meth)acrylate having 1 to 3 carbon atoms in the alkyl group contained in the acrylic resin may be of one type or two or more types.
Examples of alkyl (meth)acrylates having 1 to 3 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate and the like. . Among these, methyl (meth)acrylate and ethyl (meth)acrylate are preferred, and methyl methacrylate and ethyl acrylate are more preferred.
The content of structural units derived from alkyl (meth)acrylates having 1 to 3 carbon atoms in the alkyl group is preferably 1 to 35% by mass, in the structural units derived from acrylic monomers constituting the acrylic resin. It is preferably 5 to 30% by mass, more preferably 15 to 25% by mass.

The acrylic resin preferably further contains structural units derived from functional group-containing monomers.
When the acrylic resin contains a structural unit derived from a functional group-containing monomer, the functional group as a cross-linking starting point that reacts with the cross-linking agent or reacts with the unsaturated group-containing compound to create an unsaturated group in the side chain of the acrylic resin. Functional groups can be introduced that allow the introduction of saturated groups.
The structural unit derived from the functional group-containing monomer contained in the acrylic resin may be one type alone or two or more types.

Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxy group-containing monomers, amino group-containing monomers, and epoxy group-containing monomers.
Examples of hydroxy group-containing monomers 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; unsaturated alcohols such as vinyl alcohol and allyl alcohol;
Carboxy group-containing monomers include, for example, ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and their anhydrides ; 2-carboxyethyl methacrylate; and the like.
Among these, hydroxy group-containing monomers are preferred, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl acrylate is even more preferred.

The content of the structural unit derived from the functional group-containing monomer is preferably 1 to 35% by mass, more preferably 5 to 30% by mass, more preferably 15% by mass in the structural unit derived from the acrylic monomer constituting the acrylic resin. ~25% by mass.

The acrylic resin may contain, in addition to the above structural units, structural units derived from other monomers copolymerizable with acrylic monomers.
Constituent units derived from other monomers contained in the acrylic resin may be one type alone or two or more types.
Other monomers include, for example, styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide and the like.

The acrylic resin may further have an energy ray polymerizable unsaturated group introduced thereinto to impart energy ray curability.
The unsaturated group is, for example, a functional group of an acrylic resin containing structural units derived from a functional group-containing monomer, and a compound having a reactive substituent and an unsaturated group having reactivity with the functional group (hereinafter referred to as " (also referred to as "unsaturated group-containing compound").
The unsaturated group-containing compounds may be used singly or in combination of two or more.
Examples of the unsaturated group that the unsaturated group-containing compound has include a (meth)acryloyl group, a vinyl group, and an allyl group. Among these, a (meth)acryloyl group is preferred.
Examples of reactive substituents that the unsaturated group-containing compound has include an isocyanate group and a glycidyl group.
Examples of unsaturated group-containing compounds include 2-(meth)acryloyloxyethyl isocyanate, (meth)acryloylisocyanate, glycidyl (meth)acrylate and the like. Among these, 2-(meth)acryloyloxyethyl isocyanate is preferred, and 2-methacryloyloxyethyl isocyanate is more preferred.

When an acrylic resin containing a structural unit derived from a functional group-containing monomer is reacted with an unsaturated group-containing compound, among the total number of functional groups in the acrylic resin, a functional group that reacts with the unsaturated group-containing compound. is not particularly limited, but is preferably 30 to 90 mol%, more preferably 40 to 80 mol%, still more preferably 50 to 70 mol%.
When the ratio of the functional group that reacts with the unsaturated group-containing compound is within the above range, sufficient energy ray curability can be imparted to the acrylic resin, and the functional group that has not reacted with the unsaturated group-containing compound is crosslinked. The acrylic resin can be crosslinked by reacting with the agent.

The mass average molecular weight (Mw) of the acrylic resin is not particularly limited, but is preferably 300,000 to 1,500,000, more preferably 450,000 to 1,000,000, and still more preferably 600,000 to 900,000. When the mass average molecular weight (Mw) of the acrylic resin is within the above range, the pressure-sensitive adhesive layer tends to have better adhesive strength and cohesive strength.

The content of the acrylic resin in the adhesive composition is preferably 70 to 99% by mass, more preferably 80 to 98% by mass, relative to the total amount (100% by mass) of the active ingredients of the adhesive composition. It is preferably 90 to 97% by mass.

[Crosslinking agent]
When the pressure-sensitive adhesive composition contains a pressure-sensitive adhesive resin having a functional group, it preferably further contains a cross-linking agent.
The cross-linking agent reacts with the adhesive resin having a functional group to cross-link the adhesive resins using the functional group as a cross-linking starting point.
The cross-linking agents may be used alone or in combination of two or more.

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. Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoints of increasing cohesive strength and improving adhesive strength, and from the viewpoints of availability and the like.

Examples of isocyanate-based cross-linking agents include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate; Alicyclic polyisocyanates such as methylcyclohexylene diisocyanate, methylenebis(cyclohexyl isocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, hydrogenated xylylene diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate acyclic aliphatic polyisocyanates such as; polyvalent isocyanate compounds such as;
Examples of isocyanate-based cross-linking agents include trimethylolpropane adduct-type modified products of the polyvalent isocyanate compounds, biuret-type modified products reacted with water, isocyanurate-type modified products containing an isocyanurate ring, and the like.
Among these, trimethylolpropane adduct-type modified polyisocyanate compounds are preferred, trimethylolpropane adduct-type modified aromatic polyisocyanate compounds are more preferred, and trimethylolpropane adduct-type modified tolylene diisocyanate is even more preferred. .

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately adjusted according to the number of functional groups possessed by the pressure-sensitive adhesive resin, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive resin. parts, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 5 parts by mass.

[Photopolymerization initiator]
The pressure-sensitive adhesive composition preferably further contains a photopolymerization initiator. When the energy ray-curable pressure-sensitive adhesive contains a photopolymerization initiator, the energy ray curing reaction tends to proceed sufficiently even with relatively low-energy energy rays such as ultraviolet rays.
A photoinitiator may be used individually by 1 type, and may use 2 or more types together.

Examples of photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram. monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloroanthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and the like. Among these, 2,2-dimethoxy-2-phenylacetophenone is preferred.

The content of the photopolymerization initiator in the adhesive composition is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 100 parts by mass of the total amount of the adhesive resin. is 0.05 to 3 parts by mass.

[Tackifier]
The pressure-sensitive adhesive composition may further contain a tackifier from the viewpoint of further improving the adhesive strength.
The tackifier may be used alone or in combination of two or more.
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.
When the adhesive composition contains a tackifier, the content of the tackifier is preferably 0.01 to 65% by mass, relative to the total amount (100% by mass) of the active ingredients of the adhesive composition, and more It is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass.

[Energy ray-curable compound]
The pressure-sensitive adhesive composition may further contain an energy ray-curable compound other than the above components for the purpose of adjusting the cohesion of the pressure-sensitive adhesive layer.
The energy ray-curable compounds may be used singly or in combination of two or more.
Examples of energy ray-curable compounds include monomers or oligomers that can be polymerized and cured by energy ray irradiation.
Examples of energy ray-curable compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butylene glycol. Polyvalent (meth)acrylate monomers such as di(meth)acrylate and 1,6-hexanediol (meth)acrylate; urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate oligomers such as acrylate; Among these, from the viewpoint of curability, dipentaerythritol hexa(meth)acrylate is preferred, and dipentaerythritol hexaacrylate is more preferred.
When the pressure-sensitive adhesive composition contains an energy ray-curable compound, the content of the energy ray-curable compound is not particularly limited, but is preferably 10 to 100 parts by mass, more preferably 10 to 100 parts by mass, based on 100 parts by mass of the adhesive resin. is 20 to 70 parts by mass, more preferably 30 to 40 parts by mass.

[Thermal expandable particles]
When the adhesive layer is a thermally expandable layer containing thermally expandable particles, the adhesive layer can be formed from an adhesive composition containing thermally expandable particles. Preferred aspects of the type and content of the thermally expandable particles are the same as the preferred aspects of the type and content of the thermally expandable particles in the description of the thermally expandable layer above.

[Additive for adhesive]
In one aspect of the present invention, the pressure-sensitive adhesive composition contains additives for pressure-sensitive adhesives that are commonly used in pressure-sensitive adhesives, in addition to the components described above, within a range that does not impair the effects of the present invention. good too.
Examples of such adhesive additives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), and ultraviolet absorbers.
These adhesive additives may be used singly or in combination of two or more.
When the adhesive composition contains these adhesive additives, the content of each adhesive additive is preferably 0.0001 to 0.0001 to 100 parts by mass of the adhesive resin independently. 20 parts by mass, more preferably 0.001 to 10 parts by mass.

[Thickness of adhesive layer]
The thickness of the pressure-sensitive adhesive layer is preferably 1-80 μm, more preferably 2-60 μm, still more preferably 3-40 μm. When the thickness of the adhesive layer is 1 μm or more, good adhesiveness is obtained, and the circuit surface of the semiconductor wafer (W) tends to be better protected during processing. Moreover, when the thickness of the adhesive layer is 80 μm or less, it tends to be easy to suppress the generation of tape scraps when the adhesive sheet is cut.

(Manufacturing method of adhesive sheet for semiconductor processing)
The method for producing the adhesive sheet of one embodiment of the present invention is not particularly limited, and the adhesive sheet can be produced by a known method.
The pressure-sensitive adhesive sheet for semiconductor processing of one embodiment of the present invention can be produced, for example, by forming an intermediate layer on a substrate and then laminating a pressure-sensitive adhesive layer on the intermediate layer.

A commercially available base material may be used for the base material of the pressure-sensitive adhesive sheet of one embodiment of the present invention, and may be formed by a known method.
When the substrate is a substrate laminate in which a thermally expandable substrate and a non-thermally expandable substrate are laminated, the substrate laminate includes, for example, a thermally expandable substrate on one side of the non-thermally expandable substrate. It can be formed by applying the solventless resin composition for forming the substrate and then irradiating it with an energy ray.
As a method for applying the solventless resin composition, known methods can be used, for example, spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, and die coating. method, gravure coating method, and the like.

Examples of the method for forming the intermediate layer on the substrate include a method in which the intermediate layer composition is applied onto the substrate and then cured by irradiation with energy rays.
The method for applying the intermediate layer composition includes the same method as the method for applying the solventless resin composition.

Although the intermediate layer composition may be irradiated with energy rays only once, it is preferable to irradiate the intermediate layer multiple times from the viewpoint of facilitating control of the degree of curing of the intermediate layer.
When the energy beam is ultraviolet rays, the ultraviolet irradiation conditions for the first irradiation are such that the ultraviolet illuminance is preferably 30 to 500 mW/cm ² , more preferably 50 to 340 mW/cm ² , and the ultraviolet irradiation amount is It is preferably 100 to 2,500 mJ/cm ² , more preferably 150 to 2,000 mJ/cm ² .
The ultraviolet irradiation conditions for the second irradiation are such that the ultraviolet irradiation intensity is preferably 100 to 1,000 mW/cm ² , more preferably 200 to 500 mW/cm ² , and the ultraviolet irradiation amount is preferably 300 to 5,000 mW/cm 2 . 000 mJ/cm ² , more preferably 500 to 3,000 mJ/cm ² . It is preferable that the illuminance and the amount of irradiation be higher than the illuminance and the amount of irradiation in the irradiation of the first time.
Irradiation with energy rays is preferably carried out in a state in which the coating film is shielded from oxygen. As a method of shielding the coating film from oxygen, for example, a method of sticking a release sheet on the coating film can be mentioned.

Another method for forming an intermediate layer on a substrate includes, for example, applying the intermediate layer composition described above to the release-treated surface of a release sheet, and then irradiating an energy beam to form an intermediate layer, A method of attaching the intermediate layer to one surface of the base material may be mentioned. Preferred aspects of the method of applying the intermediate layer composition and the irradiation conditions of energy rays are the same as those described above.

Next, a pressure-sensitive adhesive layer is laminated on the surface of the intermediate layer of the substrate-attached intermediate layer. If a release sheet is attached to the intermediate layer, the release sheet is peeled off.
As a method of laminating the pressure-sensitive adhesive layer on the intermediate layer, for example, a method of directly applying the pressure-sensitive adhesive composition to the surface of the intermediate layer and then drying it to form the pressure-sensitive adhesive layer may be used.
Further, as another method for laminating the adhesive layer to the intermediate layer, for example, the adhesive composition is coated on the release-treated surface of the release sheet, dried to form an adhesive layer, and the adhesive layer is formed. A method of attaching the layer to the surface of the intermediate layer may also be used.
The method of applying the adhesive composition includes the same method as the method of applying the intermediate layer composition. The conditions for drying the pressure-sensitive adhesive composition may be appropriately adjusted according to the type and content of the solvent in the pressure-sensitive adhesive composition.
As described above, a semiconductor processing pressure-sensitive adhesive sheet having a substrate, an intermediate layer and a pressure-sensitive adhesive layer in this order is obtained. When a release sheet is attached to the surface of the adhesive layer of the pressure-sensitive adhesive sheet for semiconductor processing, the pressure-sensitive adhesive sheet for semiconductor processing is subjected to the manufacturing method of one embodiment of the present invention after removing the release sheet.

[Method for manufacturing a semiconductor device]
Next, after the semiconductor wafer (W) having protrusions, which is a processing target of the method for manufacturing a semiconductor device of one embodiment of the present invention, is described, each step of the method for manufacturing a semiconductor device of one embodiment of the present invention is sequentially described. do.

<Semiconductor wafer (W)>
The semiconductor wafer (W) is obtained by forming circuits, bumps, etc. on a semiconductor wafer substrate.
Substrates for semiconductor wafers include, for example, silicon wafers; wafers of gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, etc.; and glass wafers.

The shape of the semiconductor wafer (W) in plan view is not particularly limited, but a disk-like one is usually used. The size of the disk-shaped semiconductor wafer (W) may be appropriately selected according to the equipment used in each process, the manufacturing method, etc. For example, a diameter of 8 inches (200 mm), a diameter of 12 inches (300 mm), etc. are mentioned.

The thickness of the portion of the semiconductor wafer (W) excluding the protrusions is not particularly limited, but is preferably 100 to 1,000 μm, more preferably 200 to 900 μm, from the viewpoint of handling and workability of the semiconductor wafer (W). , more preferably 300 to 800 μm.

The semiconductor wafer (W) has projections on one surface (Wα).
Examples of protrusions include circuits and bumps formed on the surface (Wα) of the semiconductor wafer (W). Among these, the semiconductor wafer (W) preferably has bumps.
Examples of bumps include bumps made of metals such as gold, silver, copper, nickel, tin, lead, and alloys containing these metals.
The shape of the bump is not particularly limited, and examples thereof include spherical, cylindrical, elliptical cylindrical, spheroidal, conical, elliptical conical, cubic, rectangular parallelepiped, and trapezoidal shapes.
The number of bumps formed on the semiconductor wafer (W) is not particularly limited, and can be appropriately changed according to design requirements.

The height of the projections of the semiconductor wafer (W) is not particularly limited, but is preferably 10 μm to 500 μm, more preferably 10 μm to 500 μm from the viewpoint of significantly exhibiting the effects of the method for manufacturing a semiconductor device according to one embodiment of the present invention. 15 to 400 μm, more preferably 20 to 300 μm.

As an example of the semiconductor wafer (W), FIG. 2 shows a schematic plan view of a semiconductor wafer W having bumps as protrusions (hereinafter also referred to as "wafer with bumps W").
A plurality of devices 6 partitioned by dividing lines 5 are formed on the surface Wα of the wafer W with bumps. A circuit (not shown) is formed in each device 6, and as shown in the enlarged view of FIG. 2, a plurality of bumps 7 are formed as protrusions.
The surface Wα of the wafer W with bumps has a device region 8 in which a plurality of devices 6 are arranged via the dividing lines 5 and a device non-formation region 9 which becomes a remaining portion when singulating.

Next, each step of the manufacturing method of one embodiment of the present invention will be described with reference to the drawings. In the drawings used in the following description, for the sake of convenience, essential parts are shown enlarged or simplified in order to facilitate understanding of the features of the present invention. Therefore, the dimensional ratio, number, etc. of each component are not necessarily the same as in reality.

<Step 1>
Step 1 is a step of attaching the pressure-sensitive adhesive sheet for semiconductor processing according to one aspect of the present invention to the surface (Wα) having the protrusions of the semiconductor wafer (W) having the protrusions, using the adhesive layer as the attachment surface. be.

FIGS. 3A and 3B show cross-sectional views for explaining the process of attaching the pressure-sensitive adhesive sheet 10 of one embodiment of the present invention to the surface Wα of the wafer W with bumps.
FIG. 3(a) corresponds to a cross-sectional view of the wafer W with bumps shown in FIG. That is, the wafer W with bumps has, on the surface Wα, a plurality of devices 6 partitioned by the dividing lines 5, a plurality of bumps 7 formed on each device 6, a device region 8 and a device non-formation region 9. FIG.
FIG. 3B shows a state in which the adhesive sheet 10 is attached to the surface Wα of the wafer W with bumps. Although illustration of each layer of the adhesive sheet 10 is omitted, the adhesive sheet 10 is attached to the surface Wα using the adhesive layer as the attachment surface, and the surface opposite to the attachment surface is the surface on the substrate side. Sα. The adhesive sheet 10 may be an adhesive sheet for semiconductor processing used in the method for manufacturing a semiconductor device according to one embodiment of the present invention, and is, for example, the adhesive sheet 10a described above.
As shown in FIG. 3B, on the substrate-side surface Sα of the adhesive sheet 10 attached to the wafer W with bumps, there are convex portions 11 caused by the bumps 7 and portions other than the convex portions 11 . A certain non-convex portion 12 is formed. In the embodiment of FIG. 3(b), the area of the pressure-sensitive adhesive sheet 10 covering the device area 8 shown in FIG. is the non-convex portion 12 .

In step 1, the method of attaching the adhesive sheet is not particularly limited, and for example, a conventionally known method using a laminator or the like can be applied.

<Step 2>
In step 2, on the substrate-side surface (Sα) of the attached pressure-sensitive adhesive sheet for semiconductor processing, convex portions caused by the protrusions and non-convex portions other than the convex portions are removed. Among these steps, this is the step of bringing the coolant into contact with the upper surface of the convex portion.

(coolant)
The coolant used in step 2 is brought into contact with the upper surface of the protrusions formed on the surface (Sα) of the adhesive sheet on the substrate side, and when the heating in step 3 is performed, the cooling effect cools the protrusions. It is used for the purpose of suppressing the thermal expansion of the adhesive sheet on the surface.

The material of the coolant is not particularly limited as long as it has a cooling effect, but it is preferably a heat conductor. When the coolant is a heat conductor, heat is conducted from the upper surface of the convex portion with which the heat conductor is in contact with the heat conductor, so that the portion having the convex portion on the surface can be cooled.

The heat conductor used as the coolant may have an artificial cooling mechanism such as a coolant or the like circulating inside in order to enhance the cooling effect. , it may be one that does not have an artificial cooling mechanism. That is, the heat conductor itself may be intentionally uncooled. Even in this case, the heat conductor can exhibit a cooling effect by naturally dissipating the heat absorbed from the portion in contact with the upper surface of the convex portion of the adhesive sheet from the surface of the heat conductor itself.

Metal is preferable as a heat conductor. Examples of metals include single metals such as copper, silver, gold, iron, zinc, lead, tin, nickel, chromium and aluminum; alloys such as stainless steel and brass. Among these, copper and aluminum are preferred, and copper is more preferred, from the viewpoint of versatility and thermal conductivity.

The thermal conductivity of the heat conductor at 20°C is preferably 50 W/m·K or more, more preferably 100 W/m·K or more, still more preferably 200 W/m·K or more, from the viewpoint of enhancing the cooling effect. again. From the viewpoint of versatility, the thermal conductivity of the coolant, which is a heat conductor, at 20 ° C. may be 1,000 W / m K or less, may be 700 W / m K or less, or may be 500 W / It may be m·K or less.

The coolant preferably has a flat surface as a surface (hereinafter also referred to as "surface (Cα)") to be brought into contact with the surface (Sα) on the substrate side.
When the coolant has a flat surface as the surface (Cα), the shape and size of the flat surface are not particularly limited. The shape and size of the surface (Cα) of the coolant is set to be substantially the same as the shape and size of the upper surface of the convex portion, and the shape of the surface (Cα) and the shape of the upper surface of the convex portion are arranged to match the shape of the surface (Cα). It becomes easy to selectively suppress the thermal expansion of the adhesive sheet in the portion having the above.

The shape and size of the coolant surface (Cα) are not limited to those described above. For example, the area of the coolant surface (Cα) may be smaller than the area of the upper surface of the convex portion. When the heat conductivity of the coolant is high, the cooling effect is likely to be exerted over a wider area than the area where the coolant surface (Cα) is in contact, so the area should be smaller than the area of the top surface of the protrusion. Even in a mode in which the surface (Cα) of the coolant having the surface is brought into contact with a part of the upper surface of the convex portion, there is a tendency that the thermal expansion of the portion of the adhesive sheet having the convex portion on the surface can be suppressed.
On the other hand, in order to further enhance the cooling effect of the coolant, the area of the surface (Cα) of the coolant may be made larger than the area of the top surface of the protrusion, and the coolant may be brought into contact with the entire top surface of the protrusion. Increasing the area of the coolant surface (Cα) tends to increase the cooling effect of the projections with which the coolant surface (Cα) is in contact.

From the viewpoint of obtaining a sufficient cooling effect, the thickness of the coolant is preferably 100 times or more, more preferably 500 times or more, and still more preferably 1,000 times or more the thickness of the thermally expandable layer. In addition, the thickness of the coolant may be 10,000 times or less, 6,000 times or less, or 3,000 times the thickness of the thermally expandable layer from the viewpoint of ease of handling. It may be below.

In FIG. 4, among the convex portions 11 generated on the substrate-side surface Sα of the adhesive sheet 10 and the non-convex portions 12 which are portions other than the convex portions, the coolant 13 is brought into contact with the upper surface of the convex portions 11. A cross-sectional view illustrating the process is shown.
In FIG. 4, the coolant 13 is in contact with the entire upper surface of the convex portion 11, and the size of the surface Cα that contacts the surface Sα of the coolant 13 on the substrate side is substantially the same as the size of the upper surface of the convex portion 11. is.

<Step 3>
In step 3, the semiconductor processing pressure-sensitive adhesive sheet is heated to a temperature (t) at which the thermally expandable particles start to expand by heating the semiconductor wafer (W) having the protrusions while being in contact with the coolant. is heated from the side of the semiconductor wafer (W) having the protrusions, and the cooling effect of the coolant suppresses the expansion of the portion of the pressure-sensitive adhesive sheet for semiconductor processing that has the protrusions as a surface, while the non- This is a step of expanding a portion having a convex portion as a surface to reduce the height difference between the convex portion and the non-convex portion.

In step 3, the semiconductor wafer (W) is heated to the expansion start temperature (t) of the thermally expandable particles or higher, so that the adhesive sheet attached to the semiconductor wafer (W) is removed from the semiconductor wafer (W) side. heat up.
As a method of heating the semiconductor wafer (W), for example, a method of heating a surface (Wβ) opposite to the surface (Wα) of the semiconductor wafer (W) may be used. When a part is exposed, the exposed surface (Wα) may be heated. The semiconductor wafer (W), which has excellent thermal conductivity, can heat the entire semiconductor wafer (W) using heat conduction even by heating a part of the semiconductor wafer (W).
The method of heating the semiconductor wafer (W) is preferably a method of bringing a heated thermal conductor into contact with the semiconductor wafer (W) from the viewpoint of facilitating control of the location to be heated and the heating temperature. A more preferred method is to bring a heated thermal conductor into contact with the surface (Wβ) of the .
The method of contacting the semiconductor wafer (W) with a heated heat conductor is preferably a method of contacting a heat conductor having a smooth surface with the semiconductor wafer (W) from the viewpoint of uniform heating. is more preferable. Examples of the heating plate include metal plates and ceramic plates.

The surface temperature of the heated thermal conductor brought into contact with the semiconductor wafer (W) is equal to or higher than the expansion start temperature (t) of the thermally expandable particles, preferably "a temperature higher than the expansion start temperature (t)", more preferably. is "expansion start temperature (t) + 2°C" or higher, more preferably "expansion start temperature (t) + 4°C" or higher, and still more preferably "expansion start temperature (t) + 5°C" or higher. In addition, the surface temperature of the heated heat conductor is preferably "expansion start temperature (t) + 50 ° C." or less from the viewpoint of energy saving and suppressing thermal change of the semiconductor wafer (W) during heat peeling. It is preferably "expansion start temperature (t) + 40°C" or lower, more preferably "expansion start temperature (t) + 30°C" or lower.
In addition, the surface temperature of the heated thermal conductor brought into contact with the semiconductor wafer (W) is preferably within the range of the expansion start temperature (t) or higher from the viewpoint of suppressing thermal change of the semiconductor wafer (W). It is 130° C. or lower, more preferably 120° C. or lower, and still more preferably 115° C. or lower.

5(a) and 5(b), the surface Wβ of the wafer W with bumps opposite to the surface Wα is expanded by the thermally expandable particles while the coolant 13 is in contact with the upper surfaces of the protrusions 11. As shown in FIGS. The step of heating above temperature (t) is shown.
As shown in FIG. 5A, the adhesive sheet 10 is heated by bringing a heating plate 14 into contact with the surface Wβ of the wafer W with bumps. At this time, the cooling effect of the coolant 13 suppresses the thermal expansion of the portion of the adhesive sheet 10 having the projections 11 with which the coolant 13 is in contact. On the other hand, the portion having the non-convex portion 12 on the surface, which is not in contact with the coolant 13, thermally expands because the cooling effect of the coolant 13 is difficult to reach.
As a result, as shown in FIG. 5B, the height of the portion 12' where the non-convex portion 12 expands in FIG. , the height difference between the convex portions 11 and the non-convex portions 12 is reduced, and the surface Sα on the substrate side is flattened.

The amount of expansion of the portion having the non-convex portion 12 on the surface in step 3 can be adjusted, for example, by the content of the thermally expandable particles in the thermally expandable layer. That is, if the height difference between the convex portion and the non-convex portion is large before step 3, the amount of expansion may be increased by increasing the content of the thermally expandable particles in the thermally expandable layer. Further, if the height difference between the convex portion and the non-convex portion is small before step 3, the amount of expansion may be reduced by reducing the content of the thermally expandable particles in the thermally expandable layer.

<Step 4>
Step 4 is a step of processing the semiconductor wafer (W) having the protrusions in a state where the base material of the adhesive sheet for semiconductor processing is fixed.

The processing performed in step 4 includes, for example, grinding the back surface of the semiconductor wafer (W) having protrusions, singulating the semiconductor wafer (W) having protrusions, and the like. Among these, the processing in the method for manufacturing a semiconductor device of one embodiment of the present invention is preferably backside grinding of a semiconductor wafer (W) having protrusions, and is backside grinding of a semiconductor wafer having bumps as protrusions. is more preferable.

FIG. 6 shows a cross-sectional view for explaining the step of thinning the wafer W with bumps while the surface Sα of the adhesive sheet 10 on the substrate side is fixed.
In FIG. 6, the substrate-side surface Sα of the adhesive sheet 10 is fixed to a support device 15 such as a chuck table, and the back surface Wβ of the bumped wafer W is ground by a grinder 16 to a desired thickness. Since the substrate-side surface Sα of the adhesive sheet 10 has excellent flatness, a uniform pressing force is applied to the entire back surface of the semiconductor wafer, and the semiconductor wafer W can be made thin with a uniform thickness.

<Peeling process>
After processing in step 4, a peeling step of peeling the adhesive sheet for semiconductor processing from the processed semiconductor wafer (W) may be performed.
When the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is formed from an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive is cured by irradiation with energy rays to reduce the peel strength of the pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive sheet is removed. exfoliate.

[Semiconductor wafer with adhesive sheet for semiconductor processing]
A semiconductor wafer with a pressure-sensitive adhesive sheet for semiconductor processing according to one aspect of the present invention is a pressure-sensitive adhesive sheet for semiconductor processing having a substrate, an intermediate layer, and an adhesive layer in this order, A semiconductor wafer with an adhesive sheet for semiconductor processing, which is attached to the surface (Wα) having the protrusions of the semiconductor wafer (W) having the protrusions,
The adhesive sheet for semiconductor processing, in plan view,
a void-containing or void-free region (a);
a region (b) having a higher void volume content than the region (a) and a thickness greater than the region (a);
A semiconductor wafer with an adhesive sheet for semiconductor processing, wherein the surface (Sα) on the substrate side is flattened by the difference in thickness between the region (a) and the region (b).

A semiconductor wafer with an adhesive sheet for semiconductor processing according to one aspect of the present invention is produced by using expandable thermally expandable particles as the thermally expandable particles in the method for manufacturing a semiconductor device according to one aspect of the present invention, and performing steps 1 to 3 above. It corresponds to a semiconductor wafer with an adhesive sheet for semiconductor processing in which the height difference between the convex portions and the non-convex portions of the adhesive sheet for semiconductor processing is reduced. Therefore, the semiconductor wafer with the pressure-sensitive adhesive sheet for semiconductor processing according to one embodiment of the present invention can be produced by the above steps 1 to 3.

That is, the region (a) containing voids or not containing voids is a convex portion generated due to the protrusion portion of the adhesive sheet for semiconductor processing attached to the semiconductor wafer (W) in plan view. This is the area where there was. The convex portion is formed in the region ( a) does not contain voids, or if it does contain voids, it has a lower volume content than region (b).
Then, the region (b) is the non-convex region of the semiconductor processing adhesive sheet of one embodiment of the present invention attached to the semiconductor wafer (W) in plan view. In step 3 of the method for manufacturing a semiconductor device according to one embodiment of the present invention, the non-convex portion is less likely to be affected by the cooling effect of the coolant. A higher volume content of voids than in a).
Thus, in the semiconductor wafer with the pressure-sensitive adhesive sheet for semiconductor processing according to one aspect of the present invention, the region (b) contains more voids than the region (a). The region (b) is thicker than the region (a) due to the presence of voids, and the difference in thickness between the region (a) and the region (b) causes the surface of the base material to (Sα) is flattened.

The present invention will be specifically described by the following examples, but the present invention is not limited to the following examples. The physical property values in each example 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

[Thickness of each layer]
It was measured at 23° C. using a constant-pressure thickness measuring instrument manufactured by Teclock Co., Ltd. (model number: “PG-02J”, standard: conforming to JIS K6783, Z1702, Z1709).

[Average particle size (D ₅₀ ) and 90% particle size (D ₉₀ ) of thermally expandable particles]
The particle distribution of the thermally expandable particles before expansion at 23° C. was measured using a laser diffraction particle size distribution analyzer (eg, product name “Mastersizer 3000” manufactured by Malvern). Then, the particle diameters corresponding to the cumulative volume frequencies of 50% and 90% calculated from the smaller particle diameter in the particle distribution are defined as the "average particle diameter of the thermally expandable particles (D ₅₀ )" and the "thermally expandable particles 90% particle diameter (D ₉₀ ) of

[Thickness accuracy of silicon wafer after back grinding]
The thickness accuracy of the silicon wafer after back grinding is measured by measuring the thickness of the entire surface of the silicon wafer at a measurement pitch of 5 mm using a thickness measuring device (manufactured by Hamamatsu Photonics Co., Ltd., product name “C8870”). The difference between the thickness and the minimum thickness was calculated and evaluated as TTV (Total Thickness Variation).

[Manufacture of adhesive sheets for semiconductor processing]
Production Examples 1-3
[Production of semiconductor processing adhesive sheets 1 to 3]
Semiconductor processing pressure-sensitive adhesive sheets 1 to 3 were produced by the method described below.
In the following description, descriptions such as "X/Y/Z=A/B/C" representing the composition of a copolymer mean that the copolymer is a copolymer of monomer X, monomer Y, and monomer Z. It is obtained by copolymerizing A parts by weight of monomer X, B parts by weight of monomer Y, and C parts by weight of monomer Z.

(Preparation of intermediate layer composition)
65 parts by mass of urethane acrylate oligomer (manufactured by Arkema Co., Ltd., trade name "CN9021 NS"), 25 parts by mass of isobornyl acrylate, 10 parts by mass of dodecyl acrylate, and a photopolymerization initiator (manufactured by IGM Resins B.V. , trade name “Omnirad 1173”, 2-hydroxy-2-methyl-1-phenylpropan-1-one) 3.4 parts by mass, and a chain transfer agent (manufactured by Showa Denko Co., Ltd., trade name “Karens MT PE1”, penta Erythritol tetrakis (3-mercaptobutyrate)) 1.0 parts by mass and thermally expandable particles (manufactured by Nouryon Co., Ltd. , product name “Expancel (registered trademark) 031-40” (DU type), expansion start temperature (t) = 88 ° C., average particle size (D ₅₀ ) = 12.6 μm, 90% particle size (D ₉₀ ) = 26 .2 μm) and were blended to obtain an intermediate layer composition which is a solventless resin composition.

(Preparation of substrate with intermediate layer)
The intermediate layer composition obtained above is coated on a substrate PET film (manufactured by Toyobo Co., Ltd., trade name "Cosmo Shine A4160", thickness 50 μm) using a knife method. An intermediate layer composition layer was formed by coating so that the thickness was 100 μm.
Next, a PET-based release film (manufactured by Lintec Corporation, trade name “SP-PET381130”, thickness 38 μm) is laminated on the exposed surface of the formed intermediate layer composition layer. The layer was shielded from oxygen. Subsequently, using a high-pressure mercury lamp, the first UV irradiation is performed under the conditions of an illuminance of 80 mW/cm ² and an irradiation amount of 200 mJ/cm ² , and then using a high-pressure mercury lamp, an illuminance of 330 mW/cm ² and an irradiation amount. The intermediate layer composition layer was cured by performing a second UV irradiation under the condition of 1,260 mJ/cm ² to produce a substrate with an intermediate layer having a release sheet.

(Preparation of adhesive composition)
Acrylic copolymer (Nippon Synthetic Chemical Industry Co., Ltd., 2-ethylhexyl acrylate (2EHA) / ethyl acrylate (EA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) = 60/15/5/20 (mass ratio) of acrylic copolymer, 2-methacryloyloxyethyl isocyanate (MOI) was reacted so as to add to 60 mol% of all hydroxy groups of the acrylic copolymer. Polymer, mass average molecular weight (Mw) 800,000) 100 parts by mass, trimethylolpropane adduct tolylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate L") 1.1 parts by mass as a cross-linking agent, and light 2.2 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins B.V., trade name “Omnirad 651”) as a polymerization initiator was blended, and toluene was added to adjust the solid content concentration. After adjusting to 30% by mass, stirring was performed for 30 minutes to prepare an adhesive composition.

(Preparation of adhesive layer with release film)
Next, the prepared adhesive composition is applied to a PET release film (manufactured by Lintec Corporation, trade name “SP-PET381130”, thickness 38 μm), dried, and a 10 μm thick adhesive on the release film. A layer was formed to obtain a pressure-sensitive adhesive layer with a release film.

(Production of adhesive sheet for semiconductor processing)
The release film of the substrate with the intermediate layer obtained above is removed, and the adhesive layer of the adhesive layer with the release film obtained above is attached to the surface of the exposed intermediate layer, and the substrate, the intermediate Semiconductor processing adhesive sheets 1 to 3 having a layer, an adhesive layer and a release sheet in this order were obtained.

Production example 4
[Production of adhesive sheet 4 for semiconductor processing]
A pressure-sensitive adhesive sheet for semiconductor processing 4 was obtained in the same manner as in Production Example 1, except that the heat-expandable particles were not added to the intermediate layer composition.

[Manufacture of semiconductor devices]
Next, a semiconductor device was manufactured using the pressure-sensitive adhesive sheet for semiconductor processing produced above.
In the following examples and comparative examples, in order to make it easier to understand the effects of the present invention, the protrusions of the silicon wafer were formed using an adhesive sheet with a PET base material, and the adhesive sheet for semiconductor processing to be attached was intentionally forming an excessively large protrusion. This makes it easy to grasp the amount of reduction in height difference between the convex portion and the non-convex portion by the manufacturing method of the present invention.

Examples 1 to 3, Comparative Example 1
(1. Formation of protrusions)
An adhesive surface of an adhesive sheet with a PET substrate (thickness: 125 μm) cut into a circle with a diameter of 60 mm was attached as a protrusion to the center of one surface of a disk-shaped silicon wafer (diameter: 200 mm, thickness: 740 μm). . As a result, a protrusion having a height of 125 μm was formed in the center of the silicon wafer.

(2. Preparation of silicon wafer with adhesive sheet for semiconductor processing)
Next, the release film is removed from the semiconductor processing pressure-sensitive adhesive sheet obtained in each production example, and the exposed pressure-sensitive adhesive layer is used as a sticking surface. (Lintec Co., Ltd., product name "RAD 3510F/12") was used to laminate at a lamination speed of 5 mm/sec and a lamination pressure of 0.3 MPa while heating the table to 65°C.
A silicon wafer having projections formed on one surface thereof by the above steps, and an adhesive sheet for semiconductor processing applied to the entire surface of the silicon wafer on which the projections are formed, before thermal expansion. A silicon wafer with an adhesive sheet for semiconductor processing was obtained.
In the following, when the silicon wafer with the pressure-sensitive adhesive sheet for semiconductor processing is viewed from above, the region containing the protrusions may be referred to as the "projection forming region" and the region not including the protrusions may be referred to as the "projection non-formation region". be.
Further, the silicon wafer with the adhesive sheet for semiconductor processing before thermal expansion is hereinafter referred to as "wafer with adhesive sheet (1)".

(3. Measurement of thickness of wafer (1) with adhesive sheet)
Next, the silicon wafer side surface of the adhesive sheet-attached wafer (1) is placed on a flat surface, and the substrate side surface is arranged so as to be the contact surface of the constant pressure thickness gauge, and the protrusion is The thickness was measured at four points for each of the portion-formed region and the projection-non-formed region. The thickness was measured at four points on the circumference of the projection-forming region, which was concentric with the projection-forming region and whose diameter was about half the diameter of the projection-forming region. . In addition, the projection non-formation area was set to four points equidistantly spaced from each other on a circumference concentric with the projection non-formation area and having a diameter of about 2/3 of the projection non-formation area. Table 1 shows the average thickness of the protrusion-formed region and the average thickness of the non-protrusion-formed region in the adhesive sheet-attached wafer (1). As shown in Table 1, the thickness of the projection-formed region is greater than the thickness of the projection-free region, indicating that the projections are formed on the base-side surface of the pressure-sensitive adhesive sheet.

(4. Heat expansion treatment of adhesive sheet)
Next, the wafer (1) with the adhesive sheet was placed on a flat surface so that the surface on the substrate side faces upward, and a cylindrical copper (60 mm diameter, 200 mm thick) coolant was placed on the wafer. It was laminated on the adhesive sheet-attached wafer (1) so that the bottom surface was aligned with the projection forming region on the surface on the base material side.
Subsequently, the copper-laminated adhesive sheet-attached wafer (1) is placed so that the surface on the silicon wafer side comes into contact with the hot plate, and the surface on the substrate side of the copper-laminated adhesive sheet does not come into contact with the hot plate. It was placed on a hot plate and heated for 2 minutes at 110° C., which is higher than the expansion start temperature of the thermally expandable particles. After that, the wafer was left standing for 60 minutes in a standard environment (23° C., 50% RH (relative humidity)) to obtain a wafer with an adhesive sheet after thermal expansion. The wafer with the adhesive sheet after thermal expansion is hereinafter referred to as "wafer with adhesive sheet (2)".

(5. Measurement of thickness of wafer (2) with adhesive sheet)
Next, the thickness of the adhesive sheet-attached wafer (2) was measured in the same manner as in "3. Thickness measurement of the adhesive sheet-attached wafer (1)". Table 1 shows the average thickness of the protrusion-formed region and the average thickness of the non-protrusion-formed region in the adhesive sheet-attached wafer (2).

From Table 1, in Examples 1 to 3, the thickness difference [(B)-(A)] in the wafer with an adhesive sheet (1) before the heat expansion treatment is greater than the thickness difference [(B)-(A)] with the wafer with the adhesive sheet after the heat expansion treatment ( It can be seen that the thickness difference [(B)-(A)] in 2) is smaller. In addition, in Examples 1 to 3, the difference in thickness to be reduced varies depending on the content of the thermally expandable particles. It can be seen that the protrusions of the pressure-sensitive adhesive sheet can be flattened by adjusting .

(6. Back surface grinding of silicon wafer)
Next, the substrate-side surface of the adhesive sheet-attached wafer (2) obtained in Example 3 and Comparative Example 1 was fixed by a chuck table, and the back surface of the silicon wafer was ground to a predetermined thickness using a grinder. was ground.
However, in Comparative Example 1, the silicon wafer cracked during back grinding due to excessively high protrusions on the surface on the base material side, so back grinding was stopped halfway. After finishing the backside grinding, the TTV of the silicon wafer after backside grinding was measured by the method described above. had been reduced.

1 base material 2 intermediate layer 3 adhesive layer 4 release sheet 5 division line 6 device 7 bump 8 device region 9

device non-forming region

10, 10a, 10b adhesive sheet for semiconductor processing 11 convex portion 11' was convex portion 11 Portion 12 Non-convex portion 12 ′ Portion 13 where non-convex portion 12 expands Coolant 14 Heating plate 15 Support device 16 Grinder W Adherend Wα One surface Wβ of adherend Other surface Sα of adherend Adhesive sheet 10 The surface of the coolant that is in contact with the substrate-side surface Cα of the substrate-side surface Sα of

Claims

It has a substrate, an intermediate layer, and an adhesive layer in this order, and one or more layers selected from the group consisting of the substrate, the intermediate layer, and the adhesive layer contain thermally expandable particles. A semiconductor device manufacturing method using a semiconductor processing pressure-sensitive adhesive sheet that is a thermally expandable layer, comprising the following steps 1 to 4.
Step 1: Attaching the adhesive sheet for semiconductor processing to the surface (Wα) having the protrusions of the semiconductor wafer (W) having the protrusions using the adhesive layer as the attachment surface Step 2: The attached semiconductor On the surface (Sα) on the base material side of the pressure-sensitive adhesive sheet for processing, among the convex portions caused by the convex portions and the non-convex portions that are portions other than the convex portions, the upper surface of the convex portions Step 3: contacting the coolant, by heating the semiconductor wafer (W) having the protrusions to the expansion start temperature (t) of the thermally expandable particles or higher while contacting the coolant, The pressure-sensitive adhesive sheet for semiconductor processing is heated from the side of the semiconductor wafer (W) having the protrusions, and the cooling effect of the coolant suppresses the expansion of the portion of the pressure-sensitive adhesive sheet for semiconductor processing having the protrusions as a surface. while expanding the portion having the non-convex portion as a surface to reduce the height difference between the convex portion and the non-convex portion Step 4: With the base material of the pressure-sensitive adhesive sheet for semiconductor processing fixed, A step of processing the semiconductor wafer (W) having the projections
The method of manufacturing a semiconductor device according to claim 1, wherein the coolant has a thermal conductivity of 50 W/m·K or more at 20°C.
The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the coolant is metal.
3. The method of manufacturing a semiconductor device according to claim 1, wherein the thickness of the coolant is 100 times or more the thickness of the thermal expansion layer.
The method of manufacturing a semiconductor device according to claim 1 or 2, wherein the intermediate layer has a thickness of 10 to 500 µm.
The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the adhesive layer has a thickness of 1 to 80 µm.
3. The method of manufacturing a semiconductor device according to claim 1, wherein the content of said thermally expandable particles is 0.05 to 25% by mass with respect to the total mass (100% by mass) of said thermally expandable layer. .
The method of manufacturing a semiconductor device according to claim 1 or 2, wherein the thermally expandable particles have an expansion start temperature (t) of 50°C or higher and lower than 125°C.
3. The method of manufacturing a semiconductor device according to claim 1, wherein said intermediate layer is said thermally expandable layer.
The heating of the semiconductor wafer (W) having the projections in the step 3 is performed by heating the surface (Wβ) opposite to the surface (Wα) of the semiconductor wafer (W) having the projections. 3. The method of manufacturing a semiconductor device according to claim 1.
The method of manufacturing a semiconductor device according to claim 1 or 2, wherein the protrusion has a height of 10 to 500 µm.
The method of manufacturing a semiconductor device according to claim 1 or 2, wherein the semiconductor wafer (W) having the protrusions is a semiconductor wafer having bumps as the protrusions.
13. The method of manufacturing a semiconductor device according to claim 12, wherein the processing in said step 4 is back grinding of said semiconductor wafer having said bumps.
A semiconductor processing pressure-sensitive adhesive sheet having a substrate, an intermediate layer, and an adhesive layer in this order is attached to the surface of a semiconductor wafer (W) having protrusions, with the adhesive layer serving as an attachment surface. A semiconductor wafer with an adhesive sheet for semiconductor processing, which is attached to (Wα),
The adhesive sheet for semiconductor processing, in plan view,
a void-containing or void-free region (a);
a region (b) having a higher void volume content than the region (a) and a thickness greater than the region (a);
A semiconductor wafer with an adhesive sheet for semiconductor processing, wherein the substrate-side surface (Sα) is flattened by a difference in thickness between the region (a) and the region (b).