WO2020158767A1

WO2020158767A1 - Expansion method and semiconductor device production method

Info

Publication number: WO2020158767A1
Application number: PCT/JP2020/003072
Authority: WO
Inventors: 啓示布施; 洋一稲男; 忠知山田
Original assignee: リンテック株式会社
Priority date: 2019-01-31
Filing date: 2020-01-29
Publication date: 2020-08-06
Also published as: TW202044439A; JPWO2020158767A1

Abstract

An expansion method comprising: adhering a first adhesive sheet (10) having a first adhesive layer (12) and a first substrate (11) to a first wafer surface (W1) of a wafer (W) having a first wafer surface (W1) and a second wafer surface (W3), and adhering a second adhesive sheet having a second adhesive layer and a second substrate to the second wafer surface (W3); making a cut from the first adhesive sheet (10) side to cut the first adhesive sheet (10) and dice the wafer (W) into a plurality of chips (CP); adhering a third adhesive sheet (30) having a third adhesive layer (32) and a third substrate (31) to the first substrate (11); separating the second adhesive sheet from the second wafer surface (W3) of the wafer (W); and stretching the third adhesive sheet (30) to widen the interval between the plurality of chips (CP).

Description

Expanding method and semiconductor device manufacturing method

The present invention relates to an expanding method and a semiconductor device manufacturing method.

In recent years, electronic devices have become smaller, lighter and more sophisticated. Semiconductor devices mounted on electronic devices are also required to be smaller, thinner, and higher in density. A semiconductor chip may be mounted in a package close to its size. Such a package is sometimes referred to as a chip scale package (CSP). One of the CSPs is a wafer level package (WLP). In WLP, external electrodes and the like are formed on a wafer before being diced into individual pieces, and finally the wafer is diced into individual pieces. The WLP includes a fan-in type and a fan-out type. In a fan-out type WLP (hereinafter sometimes abbreviated as “FO-WLP”), the semiconductor chip is covered with a sealing member so as to be a region larger than the chip size to form a semiconductor chip sealing body. Then, the redistribution layer and the external electrodes are formed not only on the circuit surface of the semiconductor chip but also on the surface region of the sealing member.

For example, in Patent Document 1, with respect to a plurality of semiconductor chips diced from a semiconductor wafer, an extended wafer is formed by surrounding the periphery with a mold member while leaving a circuit forming surface, and forming an extended wafer in a region outside the semiconductor chip. A method for manufacturing a semiconductor package is described in which a rewiring pattern is extended and formed. In the manufacturing method described in Patent Document 1, before enclosing a plurality of individual semiconductor chips in a mold member, the wafer mounting tape for expansion is attached to the plurality of semiconductor chips to expand the wafer mounting tape for expansion. The distance between them is increasing.

Moreover, in patent document 2, the 2nd base material layer, the 1st base material layer, and the 1st adhesive layer are provided in this order, and the fracture|rupture elongation of a 2nd base material layer is 400% or more. Sheets are listed. The method of manufacturing a semiconductor device described in Patent Document 2 includes a step of attaching a semiconductor wafer to the first adhesive layer of this adhesive sheet, and a step of dicing the semiconductor wafer into individual pieces to form a plurality of semiconductor chips. And stretching the adhesive sheet to widen the gap between the semiconductor chips.

International Publication No. 2010/058646 JP, 2017-076748, A

The tape used in the expanding step usually has an adhesive layer for fixing the semiconductor chip on the tape and a base material for supporting the adhesive layer. When the wafer mounting tape for expansion is stretched as described in Patent Document 1, not only the base material of the tape but also the adhesive layer is stretched. When the semiconductor chip is peeled off from the pressure-sensitive adhesive layer after the expanding step, there may be a problem that the pressure-sensitive adhesive layer remains on the surface of the semiconductor chip that was in contact with the pressure-sensitive adhesive layer. Such a defect may be referred to as an adhesive residue in the present specification.
When the expanding step is performed using the pressure-sensitive adhesive sheet described in Patent Document 2, the pressure-sensitive adhesive layer in contact with the semiconductor chip is not stretched, and thus it is considered that adhesive residue is unlikely to occur. However, since the pressure-sensitive adhesive sheet described in Patent Document 2 has a tape structure in which the second base material layer, the first base material layer, and the first pressure-sensitive adhesive layer are laminated, a simpler tape structure is used. There is a demand for an expanding method that can prevent adhesive residue from occurring. Further, in the process described in Patent Document 2, the semiconductor wafer on the pressure-sensitive adhesive sheet is diced, and the pressure-sensitive adhesive sheet is stretched as it is without being transferred to another pressure-sensitive adhesive sheet to perform the expanding step. Therefore, in order to prevent the dicing blade during dicing from reaching the second base material layer, it is necessary to carefully control the cutting depth of the dicing blade, and there is also a demand for an expanding method capable of preventing adhesive residue by a simpler method. is there.
In the expanding method, the adherend supported on the pressure-sensitive adhesive sheet is not limited to a semiconductor chip, but may be, for example, a wafer, a semiconductor device package, or a semiconductor device such as a micro LED. For these semiconductor devices as well, like the semiconductor chip, the distance between the semiconductor devices may be expanded.

An object of the present invention is to provide an expanding method capable of suppressing adhesive residue while simplifying a tape structure and a process as compared with a conventional one, and to provide a method for manufacturing a semiconductor device including the expanding method. ..

According to one aspect of the present invention, a first adhesive layer and a first base material are provided on the first wafer surface of a wafer having a first wafer surface and a second wafer surface opposite to the first wafer surface. A first adhesive sheet having is attached, a second adhesive sheet having a second adhesive layer and a second base material is attached to the second wafer surface, and a cut is made from the first adhesive sheet side, The first adhesive sheet is cut, the wafer is further diced into a plurality of chips, and a third adhesive sheet having a third adhesive layer and a third base material is attached to the first base material. An expanding method is provided in which the second adhesive sheet is peeled from the second wafer surface of the wafer, and the third adhesive sheet is stretched to expand the interval between the plurality of chips.

In the expanding method according to one aspect of the present invention, it is preferable that the cut is formed with a depth from the side of the first adhesive sheet to the second adhesive sheet.

In the expanding method according to one aspect of the present invention, it is preferable that the second wafer surface is a surface formed by grinding the back surface of the wafer.

In the expanding method according to one aspect of the present invention, it is preferable that the first adhesive sheet is attached to the surface of the first wafer before the back surface of the wafer is ground.

In the expanding method according to one aspect of the present invention, a fourth adhesive sheet is attached to the surface of the first wafer before back grinding the wafer, and the fourth adhesive sheet is attached to the first wafer after back grinding. It is preferable that the first pressure-sensitive adhesive sheet is attached to the surface of the first wafer after peeling from the surface.

In the expanding method according to one aspect of the present invention, the fourth pressure-sensitive adhesive sheet is a back grinding sheet, the first pressure-sensitive adhesive sheet is a surface protection sheet, and the thickness of the surface protection sheet is 5 μm or more and 500 μm. The following is preferable.

In the expanding method according to one aspect of the present invention, the first adhesive sheet is preferably a back grind sheet.

In the expanding method according to one aspect of the present invention, the third adhesive sheet is preferably an expanding sheet.

In the expanding method according to one aspect of the present invention, the wafer is preferably a semiconductor wafer.

In the expanding method according to one aspect of the present invention, it is preferable that the first wafer surface has a circuit.

According to an aspect of the present invention, there is provided a method for manufacturing a semiconductor device including the expanding method according to the above-described aspect of the present invention.

According to one aspect of the present invention, it is possible to provide an expanding method that can simplify the tape structure and the process as compared with the related art and can suppress the adhesive residue. According to another aspect of the present invention, it is possible to provide a method for manufacturing a semiconductor device including an expanding method capable of suppressing adhesive residue.

Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 1st Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 2nd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 3rd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 3rd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 3rd Embodiment. Sectional drawing explaining the manufacturing method which concerns on 3rd Embodiment. The top view explaining the biaxial stretching expander used in the example. FIG. 4 is a schematic diagram for explaining a method of measuring chip alignment.

[First Embodiment]
Hereinafter, an expanding method according to the present embodiment and a semiconductor device manufacturing method including the expanding method will be described.

1 (FIGS. 1A and 1B), FIG. 2 (FIGS. 2A and 2B), and FIG. 3 are schematic cross-sectional views illustrating a method for manufacturing a semiconductor device including the expanding method according to the present embodiment.

The expanding method according to the present embodiment includes the following steps (P1) to (P5).
(P1) A step of preparing a wafer in which the first adhesive sheet is attached to the first wafer surface and the second adhesive sheet is attached to the second wafer surface. The first adhesive sheet has a first adhesive layer and a first base material. The second pressure-sensitive adhesive sheet has a second pressure-sensitive adhesive layer and a second base material.
(P2) A step of making a notch from the side of the first adhesive sheet, cutting the first adhesive sheet, and further cutting the wafer into individual chips.
(P3) A step of attaching the third adhesive sheet to the first base material. The third pressure-sensitive adhesive sheet has a third pressure-sensitive adhesive layer and a third base material.
(P4) A step of peeling the second adhesive sheet from the second wafer surface of the wafer.
(P5) A step of expanding the third pressure-sensitive adhesive sheet to widen the intervals between the plurality of chips.

FIG. 1A is a diagram for explaining the step (P1). FIG. 1A shows a wafer W to which the first adhesive sheet 10 and the second adhesive sheet 20 are attached.
The semiconductor wafer W has a circuit surface W1 as a first wafer surface and a back surface W3 as a second wafer surface. A circuit W2 is formed on the circuit surface W1.

The first adhesive sheet 10 is attached to the circuit surface W1. The second adhesive sheet 20 is attached to the back surface W3. The first pressure-sensitive adhesive sheet 10 has a first pressure-sensitive adhesive layer 12 and a first base material 11. The second pressure-sensitive adhesive sheet 20 has a second pressure-sensitive adhesive layer 22 and a second base material 21. Details of the first adhesive sheet 10 and the second adhesive sheet 20 will be described later.

The semiconductor wafer W may be, for example, a silicon wafer or a compound semiconductor wafer such as gallium/arsenic. As a method for forming the circuit W2 on the circuit surface W1 of the semiconductor wafer W, a commonly used method can be used, and examples thereof include an etching method and a lift-off method.

[Back grinding process]
The semiconductor wafer W prepared in the step (P1) is preferably a wafer obtained by undergoing a back grinding step.
In the back grinding process, the surface of the semiconductor wafer W opposite to the circuit surface W1 is ground to a predetermined thickness. The back surface W3 is preferably a surface formed by grinding the back surface of the semiconductor wafer W. A surface exposed after grinding the semiconductor wafer W is referred to as a back surface W3.

The method of grinding the semiconductor wafer W is not particularly limited, and examples thereof include known methods using a grinder or the like. When the semiconductor wafer W is ground, it is preferable to adhere an adhesive sheet called a back grind sheet to the circuit surface W1 in order to protect the circuit W2. In the back surface grinding of the wafer, the circuit surface W1 side of the semiconductor wafer W, that is, the back grinding sheet side is fixed by a chuck table or the like, and the back surface side where no circuit is formed is ground by a grinder. In the present embodiment, the first adhesive sheet 10 is preferably a back grind sheet. When the first pressure-sensitive adhesive sheet 10 is used as the back-grinding sheet, the semiconductor wafer W is attached so that the circuit surface W1 faces the first pressure-sensitive adhesive layer 12 of the first pressure-sensitive adhesive sheet 10. It is preferable that the first adhesive sheet 10 as a back grinding sheet is attached to the circuit surface W1 as a first wafer surface before the back surface grinding of the semiconductor wafer W. The step of attaching the first adhesive sheet 10 to the circuit surface W1 may be referred to as the first adhesive sheet attaching step.

The thickness of the semiconductor wafer W before grinding is not particularly limited and is usually 500 μm or more and 1000 μm or less.
The thickness of the semiconductor wafer W after grinding is not particularly limited and is usually 20 μm or more and 500 μm or less.

[Step of attaching second adhesive sheet]
The semiconductor wafer W prepared in the step (P1) is preferably a wafer obtained through the back grinding step and the sticking step of sticking the second adhesive sheet 20 to the back surface W3. This attaching step may be referred to as a second adhesive sheet attaching step.
As will be described later, in the step (P2), the semiconductor wafer W is diced into a plurality of semiconductor chips CP. When dicing the semiconductor wafer W, an adhesive sheet called a dicing sheet is preferably attached to the back surface W3 in order to hold the semiconductor wafer W. In the present embodiment, the second adhesive sheet 20 is preferably a dicing sheet. When the second adhesive sheet 20 is used as the dicing sheet, the semiconductor wafer W is attached with the back surface W3 facing the second adhesive layer 22 of the second adhesive sheet 20.

[Dicing process]
FIG. 1B is a diagram for explaining the step (P2). The process (P2) may be called a dicing process. FIG. 1B shows a plurality of semiconductor chips CP held by the second adhesive sheet 20.
The semiconductor wafer W in which the first adhesive sheet 10 is attached to the circuit surface W1 and the second adhesive sheet 20 is attached to the back surface W3 is diced into individual pieces to form a plurality of semiconductor chips CP. .. In this embodiment, a cut is made from the first adhesive sheet 10 side, the first adhesive sheet 10 is cut, and the semiconductor wafer W is further cut. The circuit surfaces W1 of the plurality of semiconductor chips CP after the dicing process are in a state of being covered with the cut first adhesive sheets 10.
A cutting means such as a dicing saw is used for dicing.
The cutting depth at the time of dicing is not particularly limited as long as the first adhesive sheet 10 and the semiconductor wafer W can be separated into individual pieces. From the viewpoint of surely cutting the semiconductor wafer W, the cut in the dicing step is preferably formed at a depth from the first adhesive sheet 10 side to reach the second adhesive sheet 20. More preferably, it is formed to a depth that reaches the second adhesive layer 22. The second adhesive layer 22 is also cut into the same size as the semiconductor chip CP by dicing. Furthermore, a cut may be formed in the second base material 21 by dicing.

[Step of attaching third adhesive sheet]
FIG. 2A is a diagram for explaining the step (P3). The step (P3) may be referred to as a third adhesive sheet sticking step. FIG. 2A shows a state in which the third adhesive sheet 30 is attached to the plurality of semiconductor chips CP obtained by the dicing process. The third pressure-sensitive adhesive sheet 30 has a third pressure-sensitive adhesive layer 32 and a third base material 31. Details of the third adhesive sheet 30 will be described later.
In the present embodiment, when the third adhesive sheet 30 is attached to the circuit surface W1 side of the plurality of semiconductor chips CP, it is between the plurality of semiconductor chips CP and the third adhesive layer 32 of the third adhesive sheet 30. A laminated structure in which the individual first adhesive sheet 10 is interposed is obtained.

[Peeling Step of Second Adhesive Sheet]
FIG. 2B is a diagram for explaining the step (P4). The step (P4) may be referred to as the peeling step of the second adhesive sheet. FIG. 2B shows a state in which the second adhesive sheet 20 is peeled from the back surface W3 of the wafer W after the third adhesive sheet 30 is attached.
When the second adhesive sheet 20 is peeled off after the third adhesive sheet 30 is attached, the back surfaces W3 of the plurality of semiconductor chips CP are exposed.
When the energy ray-polymerizable compound is mixed in the second pressure-sensitive adhesive layer 22, the second pressure-sensitive adhesive layer 22 is irradiated with energy rays from the second base material 21 side to cure the energy ray-polymerizable compound. It is preferable that the second adhesive sheet 20 is peeled off after the operation.

[Expanding process]
FIG. 3 is a diagram for explaining the step (P5). The process (P5) may be called an expanding process. FIG. 3 shows a state in which the third adhesive sheet 30 is expanded after the second adhesive sheet 20 has been peeled off to expand the intervals between the plurality of semiconductor chips CP.
When expanding the intervals between the plurality of semiconductor chips CP, it is preferable to stretch the expand sheet while holding the plurality of semiconductor chips CP with an adhesive sheet called an expand sheet. In the present embodiment, it is preferable that the third adhesive sheet 30 is an expanded sheet.
The method of stretching the third adhesive sheet 30 in the expanding step is not particularly limited. As a method of stretching the third adhesive sheet 30, for example, a method of pressing the annular or circular expander to stretch the first adhesive sheet 10 and a method of gripping the outer peripheral portion of the third adhesive sheet 30 using a gripping member or the like are used. There is a method for extending the length. In the present embodiment, the spacing D1 between the plurality of semiconductor chips CP depends on the size of the semiconductor chips CP and is not particularly limited. In particular, in the plurality of semiconductor chips CP attached to one surface of the adhesive sheet, the distance D1 between the adjacent semiconductor chips CP is preferably 200 μm or more. It should be noted that the upper limit of the interval between the semiconductor chips CP is not particularly limited. The upper limit of the distance between the semiconductor chips CP may be 6000 μm, for example.

[First transfer step]
In the present embodiment, after the expanding step, a step of transferring the plurality of semiconductor chips CP attached to the third adhesive sheet 30 to another adhesive sheet (for example, a fifth adhesive sheet) (hereinafter referred to as “first Sometimes referred to as a "transfer step").
FIG. 4A is a diagram illustrating a step of transferring the plurality of semiconductor chips CP attached to the third pressure-sensitive adhesive sheet 30 to the fifth pressure-sensitive adhesive sheet 50 (hereinafter sometimes referred to as “transfer step”). Has been done.
The fifth adhesive sheet 50 is not particularly limited as long as it can hold a plurality of semiconductor chips CP. The fifth pressure-sensitive adhesive sheet 50 has a fifth base material 51 and a fifth pressure-sensitive adhesive layer 52.
When the transfer step is performed in the present embodiment, for example, after the expanding step, the fifth adhesive sheet 50 may be attached to the back surfaces W3 of the plurality of semiconductor chips CP, and then the third adhesive sheet 30 may be peeled off. preferable.

The fifth adhesive sheet 50 may be attached to the second ring frame together with the plurality of semiconductor chips CP. In this case, the second ring frame is placed on the fifth pressure-sensitive adhesive layer 52 of the fifth pressure-sensitive adhesive sheet 50, which is lightly pressed and fixed. After that, the fifth adhesive layer 52 exposed on the inner side of the ring shape of the second ring frame is pressed against the back surface W3 of the semiconductor chip CP to fix the plurality of semiconductor chips CP to the fifth adhesive sheet 50.

FIG. 4B is a diagram illustrating a step of peeling off the third adhesive sheet 30 after the fifth adhesive sheet 50 is attached.
In the present embodiment, when the third pressure-sensitive adhesive sheet 30 is peeled off, the individual first pressure-sensitive adhesive sheet 10 covering the circuit surface W1 of the semiconductor chip CP is peeled together with the third pressure-sensitive adhesive sheet 30 as an example. I will give you an explanation. It is preferable that the force of peeling the third adhesive sheet 30 from the first adhesive sheet 10 is larger than the force of peeling the first adhesive sheet 10 from the circuit surface W1 of the semiconductor chip CP. It is also possible to adopt a mode in which only the third adhesive sheet 30 is peeled off while leaving the individualized first adhesive sheet 10 covering the circuit surface W1 on the semiconductor chip CP.
When the first adhesive sheet 10 and the third adhesive sheet 30 are peeled off after attaching the fifth adhesive sheet 50, the circuit surfaces W1 of the plurality of semiconductor chips CP are exposed. It is preferable that the distance D1 between the plurality of semiconductor chips CP expanded in the expanding step is maintained even after the first adhesive sheet 10 and the third adhesive sheet 30 are peeled off.

[Second transfer process]
FIG. 5A is a diagram illustrating a step of transferring the plurality of semiconductor chips CP attached to the fifth adhesive sheet 50 to the sixth adhesive sheet 60 (hereinafter, sometimes referred to as “second transfer step”). It is shown.
It is preferable that the plurality of semiconductor chips CP transferred from the fifth adhesive sheet 50 to the sixth adhesive sheet 60 maintain the distance D1 between the semiconductor chips CP.

The sixth adhesive sheet 60 is not particularly limited as long as it can hold a plurality of semiconductor chips CP. The sixth adhesive sheet 60 has a sixth base material 61 and a sixth adhesive layer 62.
When it is desired to seal a plurality of semiconductor chips CP on the sixth adhesive sheet 60, an adhesive sheet for the sealing step is preferably used as the sixth adhesive sheet 60, and an adhesive sheet having heat resistance is used. More preferable. When a heat-resistant pressure-sensitive adhesive sheet is used as the sixth pressure-sensitive adhesive sheet 60, the sixth base material 61 and the sixth pressure-sensitive adhesive layer 62 each have heat resistance capable of withstanding the temperature imposed in the sealing step. It is preferably made of a material.

The plurality of semiconductor chips CP transferred from the fifth adhesive sheet 50 to the sixth adhesive sheet 60 are attached so that the circuit surface W1 faces the sixth adhesive layer 62.

[Sealing process]
FIG. 5B is a diagram illustrating a step of sealing a plurality of semiconductor chips CP using the sealing member 300 (hereinafter sometimes referred to as “sealing step”).

In the present embodiment, the sealing step is performed after the plurality of semiconductor chips CP have been transferred to the sixth adhesive sheet 60.
In the sealing step, the sealing body 3 is formed by covering the plurality of semiconductor chips CP with the sealing member 300 while the circuit surface W1 is protected by the sixth adhesive sheet 60. The sealing member 300 is also filled between the plurality of semiconductor chips CP. Since the circuit surface W1 and the circuit W2 are covered with the sixth adhesive sheet 60, it is possible to prevent the circuit surface W1 from being covered with the sealing member 300.

By the sealing step, the sealing body 3 in which the plurality of semiconductor chips CP separated by a predetermined distance are embedded in the sealing member 300 is obtained. In the sealing process, it is preferable that the plurality of semiconductor chips CP be covered with the sealing member 300 in a state in which the interval D1 after performing the expanding process is maintained.

After the sealing step, the sixth adhesive sheet 60 is peeled off. When the sixth adhesive sheet 60 is peeled off, the circuit surface W1 of the semiconductor chip CP and the surface 3A of the sealing body 3 that was in contact with the sixth adhesive sheet 60 are exposed.

After the expanding process described above, the transfer process and the expanding process are repeated any number of times to set the distance between the semiconductor chips CP to a desired distance, and to set the orientation of the circuit surface when sealing the semiconductor chips CP to the desired orientation. can do.

[Other processes]
After peeling the adhesive sheet from the sealing body 3, a rewiring layer forming step of forming a rewiring layer electrically connected to the semiconductor chip CP on the sealing body 3, a rewiring layer and an external terminal electrode. And a connecting step of electrically connecting and are sequentially performed. The circuit of the semiconductor chip CP and the external terminal electrode are electrically connected by the rewiring layer forming step and the external terminal electrode connecting step.
The sealing body 3 to which the external terminal electrodes are connected is separated into individual semiconductor chips CP. The method for dividing the sealing body 3 into individual pieces is not particularly limited. By separating the sealing body 3 into individual pieces, a semiconductor package for each semiconductor chip CP is manufactured. The semiconductor package having the fan-out external electrodes connected to the outside of the semiconductor chip CP is manufactured as a fan-out type wafer level package (FO-WLP).

(First adhesive sheet)
The first pressure-sensitive adhesive sheet 10 has a first base material 11 and a first pressure-sensitive adhesive layer 12. The first pressure-sensitive adhesive layer 12 is laminated on the first base material 11.

First Base Material The constituent material of the first base material 11 according to the present embodiment is not particularly limited as long as it can properly function in a desired process such as a back grinding process.
The first base material 11 is preferably composed of a film whose main material is a resin-based material. Examples of the film containing a resin-based material as a main material include, for example, ethylene-based copolymer films, polyolefin-based films, polyvinyl chloride-based films, polyester-based films, polyurethane films, polyimide films, polystyrene films, polycarbonate films, and fluororesins. Examples include films.

Examples of the ethylene-based copolymer film include an ethylene-vinyl acetate copolymer film, an ethylene-(meth)acrylic acid copolymer film and an ethylene-(meth)acrylic acid ester copolymer film.
In the present specification, “(meth)acrylic acid” means both acrylic acid and methacrylic acid, and the same applies to other similar terms.

Examples of the polyolefin film include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film and norbornene resin film.
Examples of the polyethylene film include a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film and a high density polyethylene (HDPE) film.

Examples of polyvinyl chloride films include polyvinyl chloride films and vinyl chloride copolymer films.

Examples of polyester film include polyethylene terephthalate film and polybutylene terephthalate film.

As the first base material 11, a cross-linked film of a film containing a resin-based material as a main material can also be used. Further, as the first base material 11, a modified film such as an ionomer film can also be used.
The first base material 11 may be a film made of only one selected from the group consisting of a film containing a resin-based material as a main material, a crosslinked film and a modified film, or a laminated film in which two or more kinds are combined. Good.

For the first base material 11, for example, at least one additive selected from the group consisting of pigments, flame retardants, plasticizers, antistatic agents, lubricants and fillers is added to the film containing the above resin material as a main material. Agents may be included.
Examples of pigments include titanium dioxide and carbon black.
Examples of the filler include organic materials such as melamine resin, inorganic materials such as fumed silica, and metal materials such as nickel particles.
The content of the additive contained in the film containing a resin-based material as a main material is not particularly limited, but it should be within a range in which the first base material 11 exerts a desired function and does not lose smoothness and flexibility. Is preferred.

When irradiating with ultraviolet rays as an energy ray for curing the first pressure-sensitive adhesive layer 12, the first base material 11 is preferably transparent to ultraviolet rays.
In addition, when irradiating with an electron beam as an energy ray for hardening the 1st adhesive layer 12, it is preferable that the 1st base material 11 has a transparency with respect to an electron beam.

The first base material 11 may be subjected to surface treatment or primer treatment on one side or both sides, if desired, for the purpose of improving the adhesion with the first pressure-sensitive adhesive layer 12 laminated on the surface thereof. Examples of the surface treatment include an oxidation method and a roughening method. Examples of the primer treatment include a method of forming a primer layer on the surface of the base material. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone treatment, and ultraviolet irradiation treatment. Examples of the roughening method include a sandblast method and a thermal spraying method.

The thickness of the first base material 11 is not limited as long as the first pressure-sensitive adhesive sheet can properly function in a desired process.
The thickness of the first base material 11 is preferably 20 μm or more, more preferably 25 μm or more, and further preferably 50 μm or more.
The thickness of the first base material 11 is preferably 450 μm or less, more preferably 400 μm or less, and further preferably 350 μm or less.

First Adhesive Layer The constituent material of the first adhesive layer 12 is not particularly limited as long as it can properly function in a desired process such as a back grinding process.
In the present embodiment, the first pressure-sensitive adhesive layer 12 is, for example, at least one pressure-sensitive adhesive selected from the group consisting of acrylic pressure-sensitive adhesive, urethane pressure-sensitive adhesive, polyester pressure-sensitive adhesive, rubber pressure-sensitive adhesive and silicone pressure-sensitive adhesive. It is preferable to be composed of an agent, and more preferable to be composed of an acrylic adhesive.

The first pressure-sensitive adhesive layer 12 also preferably contains an energy ray-curable pressure-sensitive adhesive. The energy ray-curable pressure-sensitive adhesive contains an energy ray-polymerizable compound.
When the first pressure-sensitive adhesive layer 12 contains an energy ray-curable pressure-sensitive adhesive, the first pressure-sensitive adhesive layer 12 is irradiated with an energy ray from the first base material 11 side to cure the energy ray-polymerizable compound. When the energy ray-polymerizable compound is cured, the cohesive force of the first adhesive layer 12 increases and the adhesive force between the first adhesive layer 12 and the adherend (semiconductor wafer W or semiconductor chip CP) decreases. It can disappear. Examples of energy rays include ultraviolet rays (UV) and electron rays (EB), and ultraviolet rays are preferable.

Examples of the energy ray-curable pressure-sensitive adhesive include “X-type pressure-sensitive adhesive composition”, “Y-type pressure-sensitive adhesive composition”, and “XY-type pressure-sensitive adhesive composition”.

The “X-type pressure-sensitive adhesive composition” is an energy ray-curable resin containing a non-energy ray-curable pressure-sensitive adhesive resin (also referred to as “adhesive resin I”) and an energy ray-curable compound other than the pressure-sensitive adhesive resin. It is an adhesive composition.

The "Y-type pressure-sensitive adhesive composition" is an energy-ray-curable pressure-sensitive adhesive resin in which an unsaturated group is introduced into a side chain of a non-energy-ray-curable pressure-sensitive adhesive resin (hereinafter, " (Also referred to as "adhesive resin II") as a main component, and does not contain an energy ray-curable compound other than the adhesive resin.

"XY-type pressure-sensitive adhesive composition" is a combination type of X-type and Y-type, that is, an energy ray-curable adhesive resin II and an energy ray-curable compound other than the adhesive resin. Adhesive composition.

Among these, it is preferable to use the XY type adhesive composition. By using the XY type pressure-sensitive adhesive composition, it is possible to have sufficient pressure-sensitive adhesive properties before curing and to sufficiently reduce the peeling force to the semiconductor wafer or the semiconductor chip after curing.

However, the pressure-sensitive adhesive in the first pressure-sensitive adhesive layer 12 may be formed from a non-energy ray curable pressure-sensitive adhesive composition that does not cure even when irradiated with energy rays. The non-energy ray-curable pressure-sensitive adhesive composition contains at least the non-energy ray-curable pressure-sensitive adhesive resin I, but does not contain the energy ray-curable pressure-sensitive adhesive resin II and the energy ray-curable compound described above. It is a composition.

In the following description, “adhesive resin” is used as a term indicating one or both of the adhesive resin I and the adhesive resin II described above. Specific examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, and silicone resin, and acrylic resin is preferable.

Hereinafter, the acrylic pressure-sensitive adhesive in which the acrylic resin is used as the adhesive resin will be described in more detail.

・Acrylic polymer (a)
An acrylic polymer (a) is used as the acrylic resin. The acrylic polymer (a) is a polymer obtained by polymerizing a monomer containing at least an alkyl (meth)acrylate. The acrylic polymer (a) contains a structural unit derived from an alkyl (meth)acrylate.
The alkyl group in the alkyl (meth)acrylate preferably has 1 to 20 carbon atoms.
The alkyl group in the alkyl (meth)acrylate may be linear or branched.
Specific examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth). ) Acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate and dodecyl (meth)acrylate. The alkyl (meth)acrylates may be used alone or in combination of two or more.

From the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer, the acrylic polymer (a) preferably contains a structural unit derived from an alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms. The carbon number of the alkyl group in the alkyl (meth)acrylate is preferably 4 or more and 12 or less, and more preferably 4 or more and 6 or less. The alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer (a), the alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms is added to the total amount of monomers (hereinafter, also simply referred to as “total amount of monomers”) constituting the acrylic polymer (a). On the other hand, it is preferably 40% by mass or more and 98% by mass or less, more preferably 45% by mass or more and 95% by mass or less, and further preferably 50% by mass or more and 90% by mass or less.

The acrylic polymer (a) contains a structural unit derived from an alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms, and in addition to the alkyl group of the alkyl group in order to adjust the elastic modulus and the adhesive property of the adhesive layer. It is preferably a copolymer containing a structural unit derived from an alkyl(meth)acrylate having 1 to 3 carbon atoms. The alkyl(meth)acrylate is preferably an alkyl(meth)acrylate having 1 or 2 carbon atoms, more preferably methyl(meth)acrylate, most preferably methyl methacrylate. In the acrylic polymer (a), the alkyl (meth)acrylate whose alkyl group has 1 to 3 carbon atoms is preferably 1% by mass or more and 30% by mass or less based on the total amount of the monomers. The content is more preferably not less than mass% and not more than 26 mass %, further preferably not less than 6 mass% and not more than 22 mass %.

-Functional group-containing monomer The acrylic polymer (a) preferably has a functional unit-containing monomer-derived structural unit in addition to the above-mentioned alkyl (meth)acrylate-derived structural unit. Examples of the functional group of the functional group-containing monomer include a hydroxyl group, a carboxy group, an amino group and an epoxy group. The functional group-containing monomer reacts with a cross-linking agent to be described later to form a cross-linking starting point, or reacts with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (a). Is possible.

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer and an epoxy group-containing monomer. These functional group-containing monomers may be used alone or in combination of two or more. Among these functional group-containing monomers, hydroxyl group-containing monomers and carboxy group-containing monomers are preferable, and hydroxyl group-containing monomers are more preferable.

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

Examples of the carboxy group-containing monomer include 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 anhydrides thereof. , 2-carboxyethyl methacrylate and the like.

The functional group-containing monomer is preferably 1% by mass or more and 35% by mass or less, and preferably 3% by mass or more and 32% by mass or less, with respect to the total amount of the monomers constituting the acrylic polymer (a). It is more preferably 6% by mass or more and 30% by mass or less.

In addition to the above, the acrylic polymer (a) may contain a structural unit derived from a monomer copolymerizable with the acrylic monomer. Examples of the constitutional unit derived from a monomer copolymerizable with the acrylic monomer include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile and acrylamide.

The above acrylic polymer (a) can be used as a non-energy ray curable adhesive resin I (acrylic resin). As the energy ray-curable acrylic resin, one obtained by reacting a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound) with the functional group of the acrylic polymer (a) is used. Can be mentioned.

The unsaturated group-containing compound is a compound having both a substituent capable of binding to the functional group of the acrylic polymer (a) and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include a (meth)acryloyl group, a vinyl group, an allyl group and a vinylbenzyl group, and a (meth)acryloyl group is preferable.

Further, examples of the substituent that the unsaturated group-containing compound has, which can be bonded to the functional group, include an isocyanate group and a glycidyl group. Therefore, examples of the unsaturated group-containing compound include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

The unsaturated group-containing compound preferably reacts with a part of the functional groups of the acrylic polymer (a), specifically, 50 mol% or more of the functional groups of the acrylic polymer (a). , 98 mol% or less is preferably reacted with the unsaturated group-containing compound, and 55 mol% or more and 93 mol% or less is more preferably reacted with the unsaturated group-containing compound. As described above, in the energy ray-curable acrylic resin, a part of the functional group remains without reacting with the unsaturated group-containing compound, so that the crosslinking agent is easily cross-linked.

The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 or more and 1.6 million or less, more preferably 400,000 or more and 1.4 million or less, and 500,000 or more and 1.2 million or less. Is more preferable. The weight average molecular weight (Mw) of the acrylic resin is a polystyrene-equivalent value measured by a gel permeation chromatography method (GPC method).

Energy ray-curable compound As the energy ray-curable compound contained in the X-type or XY-type pressure-sensitive adhesive composition, a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and cured by energy ray irradiation is used. preferable.

Examples of such energy ray-curable compounds include trimethylolpropane tri(meth)acrylate, pentaerythritol(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4- Poly(meth)acrylate monomers such as butylene glycol di(meth)acrylate and 1,6-hexanediol (meth)acrylate, as well as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate and epoxy An oligomer such as (meth)acrylate may be used.

Among these, urethane (meth)acrylate oligomers are preferable from the viewpoint of having a relatively high molecular weight and making it difficult to reduce the shear storage elastic modulus of the adhesive layer. The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray-curable compound is preferably 100 or more and 12000 or less, more preferably 200 or more and 10000 or less, and 400 or more and 8000 or less. More preferably, 600 or more and 6000 or less are particularly preferable.

The content of the energy ray-curable compound in the X-type pressure-sensitive adhesive composition is preferably 40 parts by mass or more and 200 parts by mass or less, and 50 parts by mass or more, 150 parts by mass with respect to 100 parts by mass of the adhesive resin. It is more preferably not more than 60 parts by mass, further preferably not less than 60 parts by mass and not more than 90 parts by mass.

On the other hand, the content of the energy ray-curable compound in the XY type pressure-sensitive adhesive composition is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the adhesive resin, and 2 parts by mass or more. , 20 parts by mass or less, more preferably 3 parts by mass or more and 15 parts by mass or less. In the XY type pressure-sensitive adhesive composition, since the pressure-sensitive adhesive resin is energy ray-curable, it is possible to sufficiently reduce the peeling force after the energy ray irradiation even if the content of the energy ray-curable compound is small. Is.

-Crosslinking agent It is preferable that the pressure-sensitive adhesive composition further contains a crosslinking agent. The cross-linking agent reacts with a functional group derived from a functional group monomer of the adhesive resin to cross-link the adhesive resins. Examples of the cross-linking agent include isocyanate-based cross-linking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and adducts thereof; epoxy-based cross-linking agents such as ethylene glycol glycidyl ether; hexa[1-(2-methyl)-aziridinyl ] Aziridine-based crosslinking agents such as triphosphatriazine; chelate-based crosslinking agents such as aluminum chelates; and the like. You may use these crosslinking agents individually by 1 type or in combination of 2 or more types.

Among these, the isocyanate cross-linking agent is preferable from the viewpoint of enhancing cohesive strength to improve adhesive strength, and availability.

From the viewpoint of accelerating the crosslinking reaction, the amount of the cross-linking agent is preferably 0.01 parts by mass or more and 10 parts by mass or less, and 0.03 parts by mass or more, 7 parts by mass with respect to 100 parts by mass of the adhesive resin. It is more preferably not more than 5 parts by mass, further preferably not less than 0.05 parts by mass and not more than 4 parts by mass.

-Photopolymerization initiator When the pressure-sensitive adhesive composition is energy ray curable, it is preferable that the pressure-sensitive adhesive composition further contains a photopolymerization initiator. By containing the photopolymerization initiator, the curing reaction of the pressure-sensitive adhesive composition can be sufficiently advanced even with relatively low energy energy rays such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanocene compounds, thioxanthone compounds and peroxide compounds. Furthermore, examples of the photopolymerization initiator include photosensitizers such as amine and quinone.
More specific photopolymerization initiators include, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, Mention may be made of benzoin isopropyl ether, benzyl phenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. These photopolymerization initiators may be used alone or in combination of two or more.

The blending amount of the photopolymerization initiator is preferably 0.01 parts by mass or more and 10 parts by mass or less, and 0.03 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the adhesive resin. Is more preferable, and it is further preferable that the amount is 0.05 parts by mass or more and 5 parts by mass or less.

-Other additives The pressure-sensitive adhesive composition may contain other additives as long as the effects of the present invention are not impaired. Examples of other additives include antistatic agents, antioxidants, softening agents (plasticizers), fillers, rust preventives, pigments and dyes. When these additives are compounded, the compounding amount of the additive is preferably 0.01 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the adhesive resin.

Further, the pressure-sensitive adhesive composition may be further diluted with an organic solvent from the viewpoint of improving the coatability on the substrate, the buffer layer or the release sheet, and may be referred to as a solution of the pressure-sensitive adhesive composition (referred to as a coating liquid). ) May be used.

Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol and isopropanol.

As these organic solvents, the organic solvent used at the time of synthesizing the adhesive resin may be used as it is or used at the time of synthesis so that the solution (coating solution) of the adhesive composition can be uniformly applied. One or more organic solvents other than the above-mentioned organic solvent may be added.

The thickness of the first pressure-sensitive adhesive layer 12 is preferably less than 200 μm, more preferably 5 μm or more and 80 μm or less, and further preferably 10 μm or more and 70 μm or less. When the thickness of the first pressure-sensitive adhesive layer 12 is within such a range, the proportion of the portion having low rigidity in the first pressure-sensitive adhesive sheet 10 can be reduced, and thus the chipping of the semiconductor chip that occurs during backside grinding can be further prevented.
The above is the description regarding the first pressure-sensitive adhesive layer 12.

Release Sheet A release sheet may be attached to the surface of the first adhesive sheet 10. The release sheet is specifically attached to the surface of the first adhesive layer 12 of the first adhesive sheet 10. The release sheet protects the first pressure-sensitive adhesive layer 12 during transportation and storage by being attached to the surface of the first pressure-sensitive adhesive layer 12. The release sheet is releasably attached to the first adhesive sheet 10, and is peeled off and removed from the first adhesive sheet 10 before the first adhesive sheet 10 is used (that is, before wafer back surface grinding). ..

As the release sheet, a release sheet having at least one surface subjected to a release treatment is used. Specifically, for example, a release sheet including a release sheet base material and a release agent layer formed by applying a release agent on the surface of the base material can be mentioned.

A resin film is preferable as the base material for the release sheet. Examples of the resin forming the resin film as the release sheet substrate include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin, and polyolefin resins such as polypropylene resin and polyethylene resin. To be
Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release sheet is not particularly limited, but is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less.

-Method for producing pressure-sensitive adhesive sheet The method for producing the first pressure-sensitive adhesive sheet 10 and other pressure-sensitive adhesive sheets described in the present specification is not particularly limited and can be produced by a known method.

For example, the pressure-sensitive adhesive layer provided on the release sheet can be attached to one surface of the base material to produce a pressure-sensitive adhesive sheet having the release sheet attached to the surface of the pressure-sensitive adhesive layer. Further, the buffer layer provided on the release sheet and the base material are attached to each other, and the release sheet is removed to obtain a laminate of the buffer layer and the base material. Then, the pressure-sensitive adhesive layer provided on the release sheet is attached to the base material side of the laminate to manufacture a pressure-sensitive adhesive sheet in which the release sheet is attached to the surface of the pressure-sensitive adhesive layer. When the buffer layer is provided on both sides of the base material, the adhesive layer is formed on the buffer layer. The release sheet attached to the surface of the pressure-sensitive adhesive layer may be appropriately peeled and removed before the use of the pressure-sensitive adhesive sheet.

The following method can be cited as a more specific example of the method for manufacturing an adhesive sheet. First, a pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and, if desired, a coating liquid further containing a solvent or a dispersion medium are prepared. Next, the coating liquid is applied to one surface of the base material by a coating means to form a coating film. Examples of the coating means include a die coater, a curtain coater, a spray coater, a slit coater, and a knife coater. Next, the pressure-sensitive adhesive layer can be formed by drying the coating film. The properties of the coating liquid are not particularly limited as long as the coating liquid can be applied. The coating liquid may contain a component for forming the pressure-sensitive adhesive layer as a solute, or may contain a component for forming the pressure-sensitive adhesive layer as a dispersoid. Similarly, the pressure-sensitive adhesive composition may be directly applied on one surface of the substrate or on the buffer layer to form the pressure-sensitive adhesive layer.

The following method can be given as another more specific example of the method for manufacturing an adhesive sheet. First, a coating liquid is applied on the release surface of the release sheet to form a coating film. Next, the coating film is dried to form a laminate including the pressure-sensitive adhesive layer and the release sheet. Next, a substrate may be attached to the surface of the pressure-sensitive adhesive layer of this laminate, which is opposite to the surface on the release sheet side, to obtain a laminate of the pressure-sensitive adhesive sheet and the release sheet. The release sheet in this laminate may be released as a process material, and may protect the adhesive layer until an adherend (for example, a semiconductor chip, a semiconductor wafer, etc.) is attached to the adhesive layer. Good.

When the coating liquid contains a cross-linking agent, by changing the conditions for drying the coating film (for example, temperature, time, etc.) or by performing heat treatment separately, for example, The cross-linking reaction between the (meth)acrylic copolymer and the cross-linking agent may proceed to form a cross-linking structure in the pressure-sensitive adhesive layer with a desired existing density. In order to allow the crosslinking reaction to proceed sufficiently, after the pressure-sensitive adhesive layer is laminated on the substrate by the method described above or the like, the obtained pressure-sensitive adhesive sheet is allowed to stand in an environment of, for example, 23° C. and a relative humidity of 50% for several days. You may perform curing such as placing.

The thickness of the first adhesive sheet 10 is preferably 10 μm or more, and more preferably 30 μm or more. The thickness of the first adhesive sheet 10 is preferably 500 μm or less, and more preferably 300 μm or less.

(Second adhesive sheet)
The second pressure-sensitive adhesive sheet 20 has a second base material 21 and a second pressure-sensitive adhesive layer 22. The second pressure-sensitive adhesive layer 22 is laminated on the second base material 21.

-Second Base Material The second base material 21 according to the present embodiment is not particularly limited in its constituent material as long as it can properly function in a desired process such as a dicing process.
The second base material 21 is preferably composed of a film containing a resin-based material as a main material. Examples of the film containing a resin-based material as a main material include, for example, ethylene-based copolymer films, polyolefin-based films, polyvinyl chloride-based films, polyester-based films, polyurethane films, polyimide films, polystyrene films, polycarbonate films, and fluororesins. Examples include films.
Specific examples of the film containing a resin-based material as a main material that can be used as the second base material 21 are the same as the films exemplified in the description of the first base material 11.
As the polyolefin-based film for the second base material 21, in addition to the film exemplified in the description of the first base material 11, an ethylene-propylene copolymer film can be used.

Like the first base material 11, the second base material 21 is, for example, from the group consisting of a pigment, a flame retardant, a plasticizer, an antistatic agent, a lubricant and a filler in a film containing the resin material as a main material. At least one additive selected may be contained.

Similarly to the first base material 11, the second base material 21 may have adhesiveness to one side or both sides of the second base material 21 and the second pressure-sensitive adhesive layer 22 laminated on the surface of the second base material 21, if desired. A treatment for improving may be applied.

The thickness of the second base material 21 is not limited as long as the second adhesive sheet 20 can properly function in a desired process. The preferable thickness range of the second base material 21 is the same as the thickness range described for the first base material 11. The thicknesses of the first base material 11 and the second base material 21 may be the same or different from each other.

-Second Adhesive Layer The constituent material of the second adhesive layer 22 is not particularly limited as long as it can properly function in a desired process such as a dicing process.

The second adhesive layer 22 may be composed of a non-energy ray curable adhesive or an energy ray curable adhesive.

As the non-energy ray curable pressure-sensitive adhesive, one having a desired pressure-sensitive adhesive force and removability is preferable.
Examples of the non-energy ray curable pressure sensitive adhesive include acrylic pressure sensitive adhesive, rubber pressure sensitive adhesive, silicone pressure sensitive adhesive, urethane pressure sensitive adhesive, polyester pressure sensitive adhesive and polyvinyl ether pressure sensitive adhesive. Among these non-energy ray curable adhesives, acrylic adhesives that can effectively prevent the work (semiconductor wafer W) or processed product (semiconductor chip CP) from falling off in the dicing process or the like are preferable.

On the other hand, the energy ray-curable pressure-sensitive adhesive has a reduced adhesive force upon irradiation with energy rays. Therefore, when it is desired to separate the work or processed product from the second pressure-sensitive adhesive sheet 20, irradiation with energy rays facilitates separation. be able to.

The energy ray-curable pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer 22 may be a pressure-sensitive adhesive containing a polymer having energy ray-curability as a main component.
Further, the energy ray-curable pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer 22 includes a polymer having no energy ray-curable property and at least one of an energy ray-curable polyfunctional monomer and an energy ray-curable polyfunctional oligomer. A pressure-sensitive adhesive containing the mixture of as a main component may be used.

The case where the energy ray-curable pressure-sensitive adhesive contains a polymer having energy ray-curability as the main component will be described below.

・Energy ray curable polymer (A)
The energy ray-curable polymer is a (meth)acrylic acid ester (co)polymer (A) (hereinafter referred to as "energy ray-curable group" in which a functional group (energy ray-curable group) having energy ray-curable property is introduced into a side chain. It may be referred to as a "curable polymer (A)"). The energy ray-curable polymer (A) includes a (meth)acrylic copolymer (a1) having a functional group-containing monomer unit and an unsaturated group-containing compound (a2) having a substituent bonded to the functional group. It is preferably obtained by reacting with.

・Acrylic copolymer (a1)
The acrylic copolymer (a1) is composed of a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof.

The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) is preferably a monomer having a polymerizable double bond and a functional group in the molecule. Examples of the functional group contained in the functional group-containing monomer include a hydroxy group, an amino group, a substituted amino group and an epoxy group.

More specific examples of the functional group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Etc., and these functional group-containing monomers may be used alone or in combination of two or more.

Examples of the (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1) include an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms, a cycloalkyl (meth)acrylate, and a benzyl (meth)acrylate. Is used. Among these, alkyl (meth)acrylates having an alkyl group having 1 to 18 carbon atoms are preferable, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and n-butyl (meth)acrylate. Alternatively, 2-ethylhexyl (meth)acrylate or the like is used.

The acrylic copolymer (a1) contains a structural unit derived from the functional group-containing monomer in a proportion of usually 3% by mass or more and 100% by mass or less, preferably 5% by mass or more and 40% by mass or less. , (Meth)acrylic acid ester monomer or a derivative thereof is contained in a proportion of generally 0% by mass or more and 97% by mass or less, preferably 60% by mass or more and 95% by mass or less.

The acrylic copolymer (a1) is obtained by copolymerizing the functional group-containing monomer as described above and a (meth)acrylic acid ester monomer or a derivative thereof by a conventional method. In addition to these monomers, the acrylic copolymer (a1) may be copolymerized with, for example, at least one monomer selected from the group consisting of dimethylacrylamide, vinyl formate, vinyl acetate and styrene.

By reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with the unsaturated group-containing compound (a2) having a substituent bonded to the functional group, an energy ray-curable polymer (A) is obtained. ) Is obtained.

.Unsaturated group-containing compound (a2)
The substituent that the unsaturated group-containing compound (a2) has can be appropriately selected according to the type of the functional group of the functional group-containing monomer unit that the acrylic copolymer (a1) has. For example, when the functional group is a hydroxy group, an amino group or a substituted amino group, the substituent is preferably an isocyanate group or an epoxy group, and when the functional group is an epoxy group, the substituent is an amino group, a carboxy group or an aziridinyl group. preferable.

In addition, the unsaturated group-containing compound (a2) contains one or more, five or less, preferably one or more and two or less energy-beam polymerizable carbon-carbon double bonds per molecule. There is. Specific examples of the unsaturated group-containing compound (a2) include, for example, 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-( Bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; diisocyanate compound or polyisocyanate compound, polyol compound, hydroxyethyl (meth) Acryloyl monoisocyanate compound obtained by reaction with acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl- 2-oxazoline and the like can be mentioned.

The unsaturated group-containing compound (a2) is usually 10 mol% or more and 100 mol% or less, preferably 20 mol% or more and 95 mol% or less with respect to the functional group-containing monomer of the acrylic copolymer (a1). Used.

In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), depending on the combination of the functional group and the substituent, the reaction temperature, pressure, solvent, time, presence or absence of catalyst and catalyst The reaction conditions such as the type can be appropriately selected. By appropriately selecting such reaction conditions, the functional group present in the acrylic copolymer (a1) reacts with the substituent in the unsaturated group-containing compound (a2), and the unsaturated group becomes an acrylic group. The energy ray-curable polymer (A) is obtained by being introduced into the side chain in the system copolymer (a1).

The weight average molecular weight of the energy ray-curable polymer (A) thus obtained is preferably 10,000 or more, preferably 150,000 or more and 1.5 million or less, and 200,000 or more and 1 million or less. Is more preferable. In addition, the weight average molecular weight (Mw) in this specification is a polystyrene conversion value measured by the gel permeation chromatography method (GPC method).

.Energy ray curable monomers and/or oligomers (B)
Even when the energy ray-curable pressure-sensitive adhesive has a polymer having energy ray-curability as a main component, the energy ray-curable pressure-sensitive adhesive further contains an energy ray-curable monomer and/or oligomer (B). You may.

As the energy ray-curable monomer and/or oligomer (B), for example, an ester of polyhydric alcohol and (meth)acrylic acid can be used.

Examples of the energy ray-curable monomer and/or oligomer (B) include monofunctional acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol. Tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di Examples thereof include polyfunctional acrylic acid esters such as (meth)acrylate and dimethyloltricyclodecanedi(meth)acrylate, polyester oligo(meth)acrylate, and polyurethane oligo(meth)acrylate.

When the energy ray-curable monomer and/or oligomer (B) is blended, the content of the energy ray-curable monomer and/or oligomer (B) in the energy ray-curable adhesive is 5% by mass or more and 80 It is preferably not more than 20% by mass, more preferably not less than 20% by mass and not more than 60% by mass.

・Photopolymerization initiator (C)
Here, when ultraviolet rays are used as the energy rays for curing the energy ray-curable resin composition, it is preferable to add a photopolymerization initiator (C). By using the photopolymerization initiator (C), It is possible to reduce the polymerization and curing time and the light irradiation amount.

Specific examples of the photopolymerization initiator (C) are benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, methyl benzoin benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2,4, 6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2, 2-dimethoxy-1,2-diphenylethan-1-one and the like can be mentioned. These photopolymerization initiators (C) may be used alone or in combination of two or more.

The photopolymerization initiator (C) is an energy ray-curable copolymer (A) (when an energy ray-curable monomer and/or oligomer (B) is blended, the energy ray-curable copolymer (A) is used. And 100 parts by mass of the energy ray-curable monomer and/or oligomer (B) (100 parts by mass), preferably in an amount of 0.1 parts by mass or more and 10 parts by mass or less, It is more preferable to use it in an amount in the range of 0.5 parts by mass or more and 6 parts by mass or less.

In addition to the above components, the energy ray-curable pressure-sensitive adhesive may appropriately contain other components. Examples of the other component include a polymer component or oligomer component (D) having no energy ray curability, a cross-linking agent (E), and the like.

Examples of the polymer component or oligomer component (D) having no energy ray curability include polyacrylic acid ester, polyester, polyurethane, polycarbonate, polyolefin and the like, and the weight average molecular weight (Mw) thereof is 3000 or more and 2.5 million or less. Polymers or oligomers of are preferred.

・Crosslinking agent (E)
As the cross-linking agent (E), a polyfunctional compound having reactivity with a functional group of the energy ray-curable copolymer (A) or the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts. And reactive phenolic resins.

By blending these other components (D) and (E) with the energy ray-curable pressure-sensitive adhesive, tackiness and peelability before curing, strength after curing, adhesiveness with other layers, storage stability, etc. Can be improved. The blending amount of these other components is not particularly limited and is appropriately determined within the range of 0 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the energy ray-curable copolymer (A).

Next, the case where the energy ray-curable pressure-sensitive adhesive mainly contains a mixture of a polymer component having no energy ray-curable property and an energy ray-curable polyfunctional monomer and/or oligomer will be described below.

As the polymer component having no energy ray curability, for example, the same component as the above-mentioned acrylic copolymer (a1) can be used. The content of the polymer component having no energy ray curability in the energy ray curable resin composition is preferably 20% by mass or more and 99.9% by mass or less, and 30% by mass or more and 80% by mass or less. More preferably.

As the energy ray-curable polyfunctional monomer and/or oligomer, the same ones as the above-mentioned component (B) are selected. The compounding ratio of the energy ray-curable polymer component and the energy ray-curable polyfunctional monomer and/or oligomer is 10 parts by mass or more of the polyfunctional monomer and/or oligomer with respect to 100 parts by mass of the polymer component, 150 It is preferably not more than 25 parts by mass, more preferably not less than 25 parts by mass and not more than 100 parts by mass.

Also in this case, similarly to the above, the photopolymerization initiator (C) and the crosslinking agent (E) can be appropriately blended.

The thickness of the second pressure-sensitive adhesive layer 22 is not particularly limited as long as it can properly function in each step in which the second pressure-sensitive adhesive sheet 20 is used. The thickness of the second pressure-sensitive adhesive layer 22 is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 30 μm or less, and further preferably 3 μm or more and 20 μm or less.
The above is the description regarding the second pressure-sensitive adhesive layer 22.

-Release sheet It is preferable that a release sheet for protecting the second adhesive layer 22 is attached to the second adhesive layer 22 until the second adhesive sheet 20 is used. This release sheet may be directly laminated on the second pressure-sensitive adhesive layer 22, or another layer (die bonding film or the like) may be laminated on the second pressure-sensitive adhesive layer 22 and peeled off on the other layer. The sheets may be laminated.

The structure of the release sheet is arbitrary, and a plastic film release-treated with a release agent or the like is exemplified. Examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, a silicone-based agent, a fluorine-based agent, a long-chain alkyl-based agent, or the like can be used. Among these release agents, a silicone-based agent that is inexpensive and can obtain stable performance is preferable. The thickness of the release sheet is not particularly limited, but is usually about 20 μm or more and 250 μm or less.

The thickness of the second adhesive sheet 20 is preferably 10 μm or more, more preferably 30 μm or more. The thickness of the second adhesive sheet 20 is preferably 500 μm or less, more preferably 300 μm or less.

(Third adhesive sheet)
The third pressure-sensitive adhesive sheet 30 has a third base material 31 and a third pressure-sensitive adhesive layer 32. The third pressure-sensitive adhesive layer 32 is laminated on the third base material 31.
Third Base Material The third base material 31 is not particularly limited in its constituent material as long as it can properly function in a desired process such as an expanding process.
The third base material 31 preferably has a first base material surface and a second base material surface opposite to the first base material surface.
In the third pressure-sensitive adhesive sheet 30, the third pressure-sensitive adhesive layer 32 is preferably provided on one surface of the first base material surface and the second base material surface, and the other surface is provided with the pressure-sensitive adhesive layer. Preferably not.

The material of the third base material 31 is preferably a thermoplastic elastomer or a rubber-based material, and more preferably a thermoplastic elastomer, from the viewpoint of being easily stretched greatly.

Further, as the material of the third base material 31, it is preferable to use a resin having a relatively low glass transition temperature (Tg) from the viewpoint of being easily stretched largely. The glass transition temperature (Tg) of such a resin is preferably 90° C. or lower, more preferably 80° C. or lower, and further preferably 70° C. or lower.

Examples of thermoplastic elastomers include urethane elastomers, olefin elastomers, vinyl chloride elastomers, polyester elastomers, styrene elastomers, acrylic elastomers, and amide elastomers. The thermoplastic elastomers may be used alone or in combination of two or more. As the thermoplastic elastomer, it is preferable to use a urethane elastomer from the viewpoint of being easily stretched largely.

Urethane elastomers are generally obtained by reacting a long-chain polyol, a chain extender, and a diisocyanate. The urethane elastomer is composed of a soft segment having a constitutional unit derived from a long-chain polyol and a hard segment having a polyurethane structure obtained by the reaction of a chain extender and diisocyanate.

Urethane-based elastomers can be classified into polyester-based polyurethane elastomers, polyether-based polyurethane elastomers, and polycarbonate-based polyurethane elastomers by classifying them according to the type of long-chain polyol. The urethane elastomer may be used alone or in combination of two or more. In the present embodiment, the urethane-based elastomer is preferably a polyether-based polyurethane elastomer from the viewpoint of being easily stretched greatly.

Examples of long-chain polyols include lactone-based polyester polyols, polyester polyols such as adipate-based polyester polyols; polypropylene (ethylene) polyols and polyether polyols such as polytetramethylene ether glycol; polycarbonate polyols and the like. In the present embodiment, the long-chain polyol is preferably an adipate-based polyester polyol from the viewpoint of being easily stretched greatly.

Examples of diisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate. In the present embodiment, the diisocyanate is preferably hexamethylene diisocyanate from the viewpoint of being easily stretched largely.

The chain extender includes low molecular weight polyhydric alcohols (eg, 1,4-butanediol, 1,6-hexanediol, etc.), aromatic diamines, and the like. Of these, it is preferable to use 1,6-hexanediol from the viewpoint of being easily stretched greatly.

Examples of the olefin elastomer include ethylene/α-olefin copolymer, propylene/α-olefin copolymer, butene/α-olefin copolymer, ethylene/propylene/α-olefin copolymer, ethylene/butene/α- Selected from the group consisting of olefin copolymers, propylene/butene-α olefin copolymers, ethylene/propylene/butene-α/olefin copolymers, styrene/isoprene copolymers, and styrene/ethylene/butylene copolymers. An elastomer containing at least one resin may be mentioned. The olefin elastomers may be used alone or in combination of two or more.

The density of the olefin elastomer is not particularly limited. For example, the density of the olefin elastomers, 0.860 g / cm ³ or more is preferably less than ^{0.905g / cm 3, 0.862g / cm} 3 or more, more is less than 0.900 g / cm ³ It is preferably 0.864 g/cm ³ or more and less than 0.895 g/cm ³ . When the density of the olefin-based elastomer satisfies the above range, the base material is excellent in unevenness followability and the like when a semiconductor device such as a semiconductor wafer as an adherend is attached to an adhesive sheet.

The olefin elastomer has a mass ratio (also referred to as “olefin content” in the present specification) of the monomer composed of the olefin compound in all the monomers used to form the elastomer of 50 mass %. As described above, it is preferably 100% by mass or less.
If the olefin content is excessively low, the property as an elastomer containing a structural unit derived from olefin becomes difficult to appear, and the base material becomes difficult to exhibit flexibility and rubber elasticity.
From the viewpoint of stably obtaining flexibility and rubber elasticity, the olefin content is preferably 50% by mass or more, and more preferably 60% by mass or more.

Styrene-based elastomers include styrene-conjugated diene copolymers and styrene-olefin copolymers. Specific examples of the styrene-conjugated diene copolymer include styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer, styrene-isoprene copolymer, Unhydrogenated styrene-conjugated diene copolymer such as styrene-isoprene-styrene copolymer (SIS), styrene-ethylene-isoprene-styrene copolymer, styrene-ethylene/propylene-styrene copolymer (SEPS, styrene- Hydrogenated styrene-conjugated diene copolymers such as isoprene-styrene copolymer water additives) and styrene-ethylene-butylene-styrene copolymers (SEBS, styrene-butadiene copolymer hydrogenated products) Can be mentioned. Further, industrially, as a styrene-based elastomer, toughprene (manufactured by Asahi Kasei Corporation), Kraton (manufactured by Kraton Polymer Japan Co., Ltd.), Sumitomo TPE-SB (manufactured by Sumitomo Chemical Co., Ltd.), Epofriend (manufactured by Daicel Corporation ), Lavalon (manufactured by Mitsubishi Chemical Co., Ltd.), Septon (manufactured by Kuraray Co., Ltd.), and Tuftec (manufactured by Asahi Kasei Co., Ltd.). The styrene elastomer may be a hydrogenated product or an unhydrogenated product.

Examples of rubber materials include natural rubber, synthetic isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber ( IIR), halogenated butyl rubber, acrylic rubber, urethane rubber, and polysulfide rubber. These rubber materials can be used alone or in combination of two or more.

The third base material 31 is preferably a single-layer film, not a laminated film in which a plurality of films made of the above-mentioned materials (for example, thermoplastic elastomer or rubber-based material) are laminated. Also, the third base material 31 is not a laminated film in which a film made of the above-mentioned material (for example, a thermoplastic elastomer or a rubber-based material) and another film are laminated, but a single-layer film. Is preferred.

The third base material 31 may include an additive in the film containing the resin material as a main material. Specific examples of the additives are the same as the additives described in the description of the first base material 11 and the second base material 21. The content of the additive that may be contained in the film is not particularly limited, but it is preferable to keep it within the range in which the third base material 31 can exhibit a desired function.

Like the first base material 11 and the second base material 21, the third base material 31 has a third pressure-sensitive adhesive layer 32 laminated on one surface or both surfaces of the third base material 31 on the surface of the third base material 31. May be subjected to a treatment for improving the adhesion.

When the third pressure-sensitive adhesive layer 32 contains an energy ray-curable pressure-sensitive adhesive, the third base material 31 preferably has permeability to energy rays. When ultraviolet rays are used as the energy rays, it is preferable that the third base material 31 is transparent to ultraviolet rays. When an electron beam is used as the energy beam, the third base material 31 preferably has electron beam transparency.

The thickness of the third base material 31 is not limited as long as the third adhesive sheet 30 can properly function in a desired process. The thickness of the third base material 31 is preferably 20 μm or more, and more preferably 40 μm or more. Further, the thickness of the third base material 31 is preferably 250 μm or less, and more preferably 200 μm or less.

In addition, the thickness standard of the third base material 31 when the thickness of a plurality of locations is measured at 2 cm intervals in the in-plane direction of the first base material surface or the second base material surface of the third base material 31. The deviation is preferably 2 μm or less, more preferably 1.5 μm or less, and further preferably 1 μm or less. When the standard deviation is 2 μm or less, the third pressure-sensitive adhesive sheet 30 has a highly accurate thickness, and the third pressure-sensitive adhesive sheet 30 can be stretched uniformly.

At 23°C, the tensile elastic moduli of the MD direction and the CD direction of the third base material 31 are 10 MPa or more and 350 MPa or less, respectively, and at 23°C, the 100% stress of the MD direction and the CD direction of the third base material 31 is respectively. It is preferably 3 MPa or more and 20 MPa or less.
When the tensile elastic modulus and the 100% stress are in the above ranges, the third pressure-sensitive adhesive sheet 30 can be greatly stretched.
The 100% stress of the third base material 31 is a value obtained as follows. A test piece having a size of 150 mm (length direction)×15 mm (width direction) is cut out from the third base material 31. Grasp both ends of the cut-out test piece in the length direction with the grip so that the length between the grips is 100 mm. After gripping the test piece with the grip, it is pulled in the length direction at a speed of 200 mm/min, and the measured value of the tensile force when the length between the grips becomes 200 mm is read. The 100% stress of the third base material 31 is a value obtained by dividing the read tensile force measurement value by the cross-sectional area of the base material. The cross-sectional area of the third base material 31 is calculated by the width direction length of 15 mm×thickness of the third base material 31 (test piece). The cutting is performed so that the flow direction (MD direction) or the direction orthogonal to the MD direction (CD direction) at the time of manufacturing the base material and the length direction of the test piece match. In this tensile test, the thickness of the test piece is not particularly limited and may be the same as the thickness of the base material to be tested.

It is preferable that the breaking elongations in the MD direction and the CD direction of the third base material 31 at 23° C. are 100% or more.
When the breaking elongations in the MD direction and the CD direction of the third base material 31 are 100% or more, the third adhesive sheet 30 can be greatly stretched without causing breakage.

The tensile elastic modulus (MPa) of the substrate and the breaking elongation (%) of the substrate can be measured as follows. The substrate is cut into 15 mm×140 mm to obtain a test piece. For the test piece, the elongation at break and the tensile elastic modulus at 23° C. are measured according to JIS K7161:2014 and JIS K7127:1999. Specifically, the above test piece was set to a chuck distance of 100 mm with a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-IS 500N") and then pulled at a speed of 200 mm/min. A test is conducted to measure the elongation at break (%) and the tensile elastic modulus (MPa). In addition, the measurement is performed in both the flow direction (MD) at the time of manufacturing the base material and the direction (CD) perpendicular thereto.

-Third adhesive layer The constituent material of the third adhesive layer 32 is not particularly limited as long as it can properly function in a desired process such as an expanding process. Examples of the adhesive contained in the third adhesive layer 32 include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, polyester-based adhesives, and urethane-based adhesives.

・Energy ray curable resin (ax1)
The third pressure-sensitive adhesive layer 32 preferably contains an energy ray curable resin (ax1). The energy ray-curable resin (ax1) has an energy ray-curable double bond in the molecule.
The pressure-sensitive adhesive layer containing the energy ray-curable resin is cured by irradiation with energy rays and its adhesive strength is reduced. When it is desired to separate the adherend and the pressure-sensitive adhesive sheet, they can be easily separated by irradiating the pressure-sensitive adhesive layer with energy rays.

The energy ray curable resin (ax1) is preferably a (meth)acrylic resin.

The energy ray curable resin (ax1) is preferably an ultraviolet curable resin, and more preferably an ultraviolet curable (meth)acrylic resin.

The energy ray curable resin (ax1) is a resin that is polymerized and cured when it is irradiated with energy rays. Examples of energy rays include ultraviolet rays and electron rays.
Examples of the energy ray curable resin (ax1) include low molecular weight compounds having an energy ray polymerizable group (monofunctional monomers, polyfunctional monomers, monofunctional oligomers, and polyfunctional oligomers). The energy ray-curable resin (ax1) is specifically trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4- Butylene glycol diacrylate, acrylates such as 1,6-hexanediol diacrylate, cycloaliphatic skeleton-containing acrylates such as dicyclopentadiene dimethoxydiacrylate, and isobornyl acrylate, and polyethylene glycol diacrylate, oligoester acrylate, urethane Acrylate compounds such as acrylate oligomer, epoxy modified acrylate, polyether acrylate, and itaconic acid oligomer are used. The energy ray curable resin (a1) may be used alone or in combination of two or more.

The molecular weight of the energy ray curable resin (ax1) is usually 100 or more and 30,000 or less, preferably 300 or more and 10,000 or less.

・(Meth)acrylic copolymer (b1)
The pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) according to this embodiment preferably further contains a (meth)acrylic copolymer (b1). The (meth)acrylic copolymer is different from the energy ray curable resin (ax1) described above.

The (meth)acrylic copolymer (b1) preferably has an energy ray-curable carbon-carbon double bond. That is, in the present embodiment, the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) contains the energy ray-curable resin (ax1) and the energy ray-curable (meth)acrylic copolymer (b1). It is preferable.

The pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) according to the present embodiment has a ratio of 10 parts by mass or more of the energy ray-curable resin (ax1) to 100 parts by mass of the (meth)acrylic copolymer (b1). It is preferable that the content is 20 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 25 parts by mass or more.
The pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) according to the present embodiment has a ratio of 80 parts by mass or less of the energy ray-curable resin (ax1) to 100 parts by mass of the (meth)acrylic copolymer (b1). It is preferable that the content is 70 parts by mass or less, more preferably 70 parts by mass or less, and further preferably 60 parts by mass or less.

The weight average molecular weight (Mw) of the (meth)acrylic copolymer (b1) is preferably 10,000 or more, more preferably 150,000 or more, and further preferably 200,000 or more.
The weight average molecular weight (Mw) of the (meth)acrylic copolymer (b1) is preferably 1,500,000 or less, more preferably 1,000,000 or less.
In addition, the weight average molecular weight (Mw) in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography method (GPC method).

The (meth)acrylic copolymer (b1) is a (meth)acrylic acid ester polymer (b2) (hereinafter referred to as “energy” in which a functional group having energy ray curability (energy ray curable group) is introduced into a side chain. It may be referred to as a "curable polymer (b2)").

・Energy ray curable polymer (b2)
The energy ray-curable polymer (b2) is obtained by reacting an acrylic copolymer (b21) having a functional group-containing monomer unit with an unsaturated group-containing compound (b22) having a functional group bonded to the functional group. It is preferably a copolymer obtained as described above.

In the present specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

The acrylic copolymer (b21) preferably contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative of a (meth)acrylic acid ester monomer. ..

The functional group-containing monomer as a constituent unit of the acrylic copolymer (b21) is preferably a monomer having a polymerizable double bond and a functional group in the molecule. The functional group is preferably at least one functional group selected from the group consisting of a hydroxy group, a carboxy group, an amino group, a substituted amino group, an epoxy group and the like.

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl ( Examples thereof include (meth)acrylate and 4-hydroxybutyl (meth)acrylate. The hydroxy group-containing monomer may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. The carboxy group-containing monomer is used alone or in combination of two or more.

Examples of the amino group-containing monomer or the substituted amino group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. The amino group-containing monomer or the substituted amino group-containing monomer may be used alone or in combination of two or more.

Examples of the (meth)acrylic acid ester monomer that constitutes the acrylic copolymer (b21) include alkyl (meth)acrylates having an alkyl group having 1 to 20 carbon atoms, as well as, for example, an alicyclic structure in the molecule. A monomer having a (alicyclic structure-containing monomer) is preferably used.

As the alkyl (meth)acrylate, an alkyl (meth)acrylate whose alkyl group has 1 to 18 carbon atoms is preferable. The alkyl(meth)acrylate is more preferably, for example, methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, n-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, or the like. Alkyl (meth)acrylate is used individually by 1 type or in combination of 2 or more type.

Examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. , And dicyclopentenyloxyethyl (meth)acrylate are preferably used. The alicyclic structure-containing monomer may be used alone or in combination of two or more.

The acrylic copolymer (b21) preferably contains the structural unit derived from the functional group-containing monomer in a proportion of 1% by mass or more, more preferably 5% by mass or more. It is more preferable that the content is at least mass %.
The acrylic copolymer (b21) preferably contains the structural unit derived from the functional group-containing monomer in a proportion of 35% by mass or less, more preferably 30% by mass or less. It is more preferable that the content is 25 mass% or less.

Furthermore, the acrylic copolymer (b21) preferably contains a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof in a proportion of 50% by mass or more, and a proportion of 60% by mass or more. Is more preferable, and it is further preferable that the content is 70% by mass or more.
The acrylic copolymer (b21) preferably contains a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof in a proportion of 99% by mass or less, and a proportion of 95% by mass or less. Is more preferable, and it is further preferable that the content is 90% by mass or less.

The acrylic copolymer (b21) is obtained by copolymerizing the functional group-containing monomer as described above and the (meth)acrylic acid ester monomer or a derivative thereof by a conventional method.
The acrylic copolymer (b21) may contain at least one structural unit selected from the group consisting of dimethylacrylamide, vinyl formate, vinyl acetate, and styrene, in addition to the above-mentioned monomers. ..

The energy ray-curable polymer (b2) is obtained by reacting the acrylic copolymer (b21) having the functional group-containing monomer unit with the unsaturated group-containing compound (b22) having a functional group bonded to the functional group. ) Is obtained.

The functional group of the unsaturated group-containing compound (b22) can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (b21). For example, when the functional group of the acrylic copolymer (b21) is a hydroxy group, an amino group or a substituted amino group, the functional group of the unsaturated group-containing compound (b22) is preferably an isocyanate group or an epoxy group, and an acrylic group When the functional group contained in the copolymer (b21) is an epoxy group, the functional group contained in the unsaturated group-containing compound (b22) is preferably an amino group, a carboxy group or an aziridinyl group.

The unsaturated group-containing compound (b22) contains at least one energy ray-polymerizable carbon-carbon double bond in one molecule, preferably one or more and 6 or less, and preferably one or more and 4 or less. It is more preferable to include the following.

Examples of the unsaturated group-containing compound (b22) include 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1 -(Bisacryloyloxymethyl)ethyl isocyanate; an acryloyl monoisocyanate compound obtained by reacting a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; a diisocyanate compound or polyisocyanate compound, a polyol compound, and hydroxyethyl ( Acryloyl monoisocyanate compound obtained by reaction with (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-iso Propenyl-2-oxazoline and the like can be mentioned.

The unsaturated group-containing compound (b22) is preferably used in a proportion (addition rate) of 50 mol% or more, and 60 mol% relative to the number of moles of the functional group-containing monomer of the acrylic copolymer (b21). It is more preferably used in the above ratio, and further preferably used in a ratio of 70 mol% or more.
Further, the unsaturated group-containing compound (b22) is preferably used in a proportion of 95 mol% or less, and in a proportion of 93 mol% or less, with respect to the number of moles of the functional group-containing monomer of the acrylic copolymer (b21). It is more preferably used, and further preferably used in a proportion of 90 mol% or less.

In the reaction between the acrylic copolymer (b21) and the unsaturated group-containing compound (b22), the functional group of the acrylic copolymer (b21) and the functional group of the unsaturated group-containing compound (b22) Depending on the combination, the reaction temperature, pressure, solvent, time, presence or absence of catalyst, and type of catalyst can be appropriately selected. As a result, the functional group of the acrylic copolymer (b21) reacts with the functional group of the unsaturated group-containing compound (b22), and the unsaturated group becomes a side chain of the acrylic copolymer (b21). This is introduced to obtain the energy ray-curable polymer (b2).

The weight average molecular weight (Mw) of the energy ray-curable polymer (b2) is preferably 10,000 or more, more preferably 150,000 or more, and further preferably 200,000 or more.
The weight average molecular weight (Mw) of the energy ray-curable polymer (b2) is preferably 1,500,000 or less, more preferably 1,000,000 or less.

・Photopolymerization initiator (CX)
When the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) contains a UV-curable compound (for example, a UV-curable resin), the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) is a photopolymerization initiator (CX). It is preferable to contain
When the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) contains the photopolymerization initiator (CX), the polymerization and curing time and the light irradiation amount can be reduced.

Specific examples of the photopolymerization initiator (CX) are the same as the specific examples of the photopolymerization initiator (C) in the description of the second adhesive sheet 20. Also in the third adhesive sheet 30, the photopolymerization initiator (CX) may be used alone or in combination of two or more.

When the energy ray-curable resin (ax1) and the (meth)acrylic copolymer (b1) are mixed in the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32), the photopolymerization initiator (CX) is an energy source. It is preferably used in an amount of 0.1 parts by mass or more, and 0.5 parts by mass or more, based on 100 parts by mass of the total amount of the linear curable resin (ax1) and the (meth)acrylic copolymer (b1). More preferably used in an amount of
Further, the photopolymerization initiator (CX) is used when the energy ray-curable resin (ax1) and the (meth)acrylic copolymer (b1) are mixed in the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32). It is preferably used in an amount of 10 parts by mass or less, and an amount of 6 parts by mass or less, based on 100 parts by mass of the total amount of the energy ray curable resin (ax1) and the (meth)acrylic copolymer (b1). Is more preferably used.

The pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) may appropriately contain other components in addition to the above components. Examples of the other component include a cross-linking agent (EX) and the like.

・Crosslinking agent (EX)
As the cross-linking agent (EX), a polyfunctional compound having reactivity with a functional group contained in the (meth)acrylic copolymer (b1) or the like can be used. Examples of the polyfunctional compound in the third adhesive sheet 30 are the same as the specific examples of the polyfunctional compound as the crosslinking agent (E) in the description of the second adhesive sheet 20.

The amount of the cross-linking agent (EX) to be blended is preferably 0.01 parts by mass or more, and preferably 0.03 parts by mass or more, with respect to 100 parts by mass of the (meth)acrylic copolymer (b1). More preferably, it is more preferably 0.04 parts by mass or more.
The amount of the crosslinking agent (EX) blended is preferably 8 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic copolymer (b1). More preferably, it is 3.5 parts by mass or less.

The thickness of the adhesive layer (third adhesive layer 32) is not particularly limited. The thickness of the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) is, for example, preferably 10 μm or more, and more preferably 20 μm or more. The thickness of the pressure-sensitive adhesive layer (third pressure-sensitive adhesive layer 32) is preferably 150 μm or less, more preferably 100 μm or less.

The restoration rate of the third pressure-sensitive adhesive sheet 30 is preferably 70% or more, more preferably 80% or more, and further preferably 85% or more. The restoration rate of the third adhesive sheet 30 is preferably 100% or less. When the restoration rate is within the above range, the pressure-sensitive adhesive sheet can be stretched greatly.
The recovery rate is obtained by grabbing both ends in the length direction with a gripper so that the length between the grippers is 100 mm in a test piece obtained by cutting out an adhesive sheet into 150 mm (length direction)×15 mm (width direction), Then, pull at a speed of 200 mm/min until the length between the grips reaches 200 mm, hold for 1 minute with the length between the grips expanded to 200 mm, and then the length between the grips is 100 mm. Until it reaches 200 mm/min in the length direction, hold for 1 minute with the length between grips returned to 100 mm, and then pull in the length direction at a speed of 60 mm/min to pull the tensile force. The length between the grips when the measured value of 0.1 N/15 mm was measured, and the length obtained by subtracting 100 mm between the initial grips from the length was defined as L2 (mm), and When the length obtained by subtracting the initial length between grips of 100 mm from the length between grips of 200 mm in the expanded state is L1 (mm), it is calculated by the following mathematical expression (Equation 2).
Recovery rate (%)={1-(L2÷L1)}×100 (Equation 2)

When the restoration rate is within the above range, it means that the pressure-sensitive adhesive sheet is easily restored even after being greatly stretched. In general, when a sheet having a yield point is stretched above the yield point, the sheet undergoes plastic deformation, and the plastically deformed portion, that is, the extremely stretched portion is unevenly distributed. When the sheet in such a state is further stretched, the expand becomes non-uniform even if the above-mentioned extremely stretched portion breaks or does not break. In the stress-strain diagram in which strain is plotted on the x-axis and elongation on the y-axis, the slope dx/dy does not take a stress value that changes from a positive value to 0 or a negative value, and a clear yield point. Even if the sheet does not show the above, the sheet is plastically deformed as the tensile amount increases, and similarly, the sheet is fractured or the expansion becomes uneven. On the other hand, when elastic deformation occurs instead of plastic deformation, the sheet is easily restored to the original shape by removing the stress. Therefore, when the restoration rate, which is an index showing how much the sheet is restored after 100% elongation, which is a sufficiently large tensile amount, is within the above range, the plastic deformation of the film is minimized when the adhesive sheet is largely stretched. It is suppressed, breakage hardly occurs, and uniform expansion becomes possible.

-Release sheet The third pressure-sensitive adhesive sheet 30 may have a release sheet laminated on the pressure-sensitive adhesive surface for the purpose of protecting the pressure-sensitive adhesive surface until the pressure-sensitive adhesive surface is attached to an adherend (for example, a semiconductor chip). Good. The configuration of the release sheet is arbitrary, and examples include those obtained by subjecting a plastic film to a release treatment with a release agent or the like. The release sheet may be a release sheet that can be used for the first adhesive sheet 10 and the second adhesive sheet 20.

The thickness of the third adhesive sheet 30 is preferably 30 μm or more, and more preferably 50 μm or more. The thickness of the third adhesive sheet 30 is preferably 400 μm or less, more preferably 300 μm or less.

[Effects of this embodiment]
According to the expanding method according to the present embodiment, when the third adhesive sheet 30 is expanded, the circuit surface W1 of the semiconductor chip CP is not in contact with the third adhesive layer 32 of the third adhesive sheet 30. In each of the semiconductor chips CP, since the first adhesive sheet 10 separated into individual pieces in the dicing process is interposed between the circuit surface W1 and the third adhesive layer 32, the third adhesive sheet 30 is expanded. However, the first pressure-sensitive adhesive layer 12 of the first pressure-sensitive adhesive sheet 10 that is in contact with the circuit surface W1 is not stretched. As a result, according to the expanding method of the present embodiment, it is possible to suppress adhesive residue.
The pressure-sensitive adhesive sheets used in the expanding method according to the present embodiment each have a simple structure including a base material and a pressure-sensitive adhesive layer. Further, before performing the expanding step, the adhesive sheet used when performing the dicing step is replaced with an adhesive sheet for the expanding step, so that the dicing blade does not reach the base material of the dicing sheet in the dicing step. Moreover, it is not necessary to carefully control the depth of cut.
Therefore, according to the expanding method of the present embodiment, the structure and process of the pressure-sensitive adhesive sheet can be simplified and the adhesive residue can be suppressed as compared with the conventional method.
Furthermore, a method of manufacturing a semiconductor device including the expanding method according to the present embodiment can be provided.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
The first embodiment and the second embodiment mainly differ in the following points. In the first embodiment, the adhesive sheet adhered to the circuit surface of the semiconductor wafer in the back grinding process and the dicing process is the same adhesive sheet, whereas in the second embodiment, the adhesive sheet is applied to the semiconductor wafer in the back grinding process. The adhesive sheet attached is different from the adhesive sheet attached to the circuit surface of the semiconductor wafer in the dicing process.
In the following description, the part related to the difference from the first embodiment will be mainly described, and the overlapping description will be omitted or simplified. The same components as those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted or simplified.

The expanding method according to this embodiment includes steps (PX1), (PX2), and (PX3) in addition to the steps (P1) to (P5) described in the first embodiment. Steps (PX1), (PX2) and (PX3) are performed before step (P1).

(PX1) A step of adhering a fourth adhesive sheet to the surface of the first wafer before backgrinding the semiconductor wafer.
(PX2) A step of grinding the back surface of the semiconductor wafer to which the fourth adhesive sheet is attached.
(PX3) A step of peeling the fourth adhesive sheet from the first wafer surface after back-grinding the semiconductor wafer and adhering the first adhesive sheet to the first wafer surface.

[Back grinding process]
FIG. 6A is a diagram for explaining the step (PX1) and the step (PX2).
In the back grinding process of this embodiment, the back surface W6 opposite to the circuit surface W1 is ground by the grinder 500, and the semiconductor wafer W is ground to a predetermined thickness. The back surface W6 of the semiconductor wafer W is ground to form a back surface W3.

In the back grinding process of this embodiment, the fourth adhesive sheet 40 is attached to the circuit surface W1 of the semiconductor wafer W. The fourth pressure-sensitive adhesive sheet 40 has a fourth pressure-sensitive adhesive layer 42 and a fourth base material 41. In the present embodiment, the fourth adhesive sheet 40 is preferably a back grind sheet. When the fourth pressure-sensitive adhesive sheet 40 is used as the back-grinding sheet, the semiconductor wafer W is attached so that the circuit surface W1 faces the fourth pressure-sensitive adhesive layer 42 of the fourth pressure-sensitive adhesive sheet 40. The fourth pressure-sensitive adhesive sheet 40 as a back-grinding sheet is preferably attached to the circuit surface W1 as the first wafer surface before back-grinding the semiconductor wafer W.
As the fourth adhesive sheet 40, it is preferable to use the same adhesive sheet as the first adhesive sheet 10 in the first embodiment.

[Peeling Step of Fourth Adhesive Sheet and Sticking Step of First Adhesive Sheet]
FIG. 6B is a diagram for explaining the step (PX3). FIG. 6B shows a state in which the first adhesive sheet 70 is attached to the circuit surface W1 after the fourth adhesive sheet 40 is peeled from the circuit surface W1 after the back surface of the semiconductor wafer W is ground.
In the present embodiment, as described above, after the backgrinding step, the backgrinding sheet (fourth adhesive sheet 40) is not attached to the circuit surface W1 and the process is not advanced to the next step. 1 Adhesive sheet 70) is attached to the circuit surface W1. The first pressure-sensitive adhesive sheet 70 as this another pressure-sensitive adhesive sheet is preferably a surface protection sheet for protecting the circuit surface W1. In the first embodiment, the first adhesive sheet is used as the back grind sheet, but in the present embodiment, the first adhesive sheet is used as the surface protection sheet, so the positioning of the first adhesive sheet is different. Therefore, in the first embodiment, the reference numeral of the first adhesive sheet is 10, and in the present embodiment, the reference numeral of the first adhesive sheet is 70 to distinguish them.
The thickness of the first pressure sensitive adhesive sheet 70 as the surface protection sheet is preferably thinner than the thickness of the fourth pressure sensitive adhesive sheet 40 as the back grinding sheet. By making the thickness of the first adhesive sheet 70 smaller than the thickness of the fourth adhesive sheet 40, it becomes easy to dice the first adhesive sheet 70 and the semiconductor wafer W in the dicing process.
The thickness of the first pressure-sensitive adhesive sheet 70 as the surface protection sheet is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 30 μm or more.
The thickness of the first pressure-sensitive adhesive sheet 70 as the surface protection sheet is preferably 500 μm or less, more preferably 300 μm or less, and further preferably 100 μm or less.

[Step of attaching second adhesive sheet]
Also in the present embodiment, as in the first embodiment, the semiconductor wafer W prepared in the step (P1) undergoes the back-grinding step and further the sticking step of sticking the second adhesive sheet 20 to the back surface W3. The obtained wafer is preferable.
FIG. 7A is a diagram illustrating a bonding step of bonding the second adhesive sheet 20 to the back surface W3. In the present embodiment, it is preferable that the second adhesive sheet 20 is a dicing sheet, as in the first embodiment. When the second adhesive sheet 20 is used as the dicing sheet, the semiconductor wafer W is attached with the back surface W3 facing the second adhesive layer 22 of the second adhesive sheet 20.

[Dicing process]
FIG. 7B is a diagram for explaining the step (P2) in the present embodiment. The process (P2) may be called a dicing process. FIG. 7B shows a plurality of semiconductor chips CP obtained by dicing the semiconductor wafer W.
The step (P2) in the present embodiment is different from the first embodiment in that the first adhesive sheet 70 is attached to the circuit surface W1, and the other points can be performed in the same manner as in the first embodiment. Also in the present embodiment, the first adhesive sheet 70 is cut, the first adhesive sheet 70 is cut, and the semiconductor wafer W is further cut.

[Step of attaching third adhesive sheet]
FIG. 8A is a diagram for explaining the step (P3). The step (P3) may be referred to as a third adhesive sheet sticking step. FIG. 8A shows a state in which the third adhesive sheet 30 is attached to the plurality of semiconductor chips CP obtained by the dicing process. The third adhesive sheet 30 is the same as that in the first embodiment.
The step (P3) in the present embodiment is different from the first embodiment in that the third pressure-sensitive adhesive sheet 30 is attached to the first pressure-sensitive adhesive sheet 70 as a surface protection sheet, and other points are the first embodiment. It can be implemented in the same manner as.

[Peeling Step of Second Adhesive Sheet]
FIG. 8B is a diagram for explaining the step (P4) in the present embodiment. The step (P4) may be referred to as the peeling step of the second adhesive sheet. FIG. 8B shows a state in which the second adhesive sheet 20 is peeled from the back surface W3 of the wafer W after the third adhesive sheet 30 is attached. The step (P4) in this embodiment can be carried out in the same manner as in the first embodiment.

[Expanding process]
FIG. 9 is a diagram for explaining the step (P5) in the present embodiment. The process (P5) may be called an expanding process. FIG. 9 shows a state in which after the second adhesive sheet 20 is peeled off, the third adhesive sheet 30 is expanded to expand the intervals between the plurality of semiconductor chips CP. Also in this embodiment, it is preferable that the third adhesive sheet 30 is an expanded sheet. The step (P5) in this embodiment can be performed in the same manner as in the first embodiment. Also in the present embodiment, the spacing D1 between the plurality of semiconductor chips CP is preferably the same as that in the first embodiment.

[Sealing process and other processes]
In the present embodiment as well, similar to the first embodiment, the sealing step and other steps (rewiring layer forming step and external terminal electrode connecting step) may be performed.

(4th adhesive sheet)
As the fourth adhesive sheet 40, it is preferable to use the same adhesive sheet as the first adhesive sheet 10 described in the first embodiment.

(First adhesive sheet)
The first pressure-sensitive adhesive sheet 70 in the present embodiment has a seventh base material 71 and a seventh pressure-sensitive adhesive layer 72. The seventh pressure-sensitive adhesive layer 72 is laminated on the seventh base material 71.

-Seventh Base Material The seventh base material 71 is a member that supports the seventh adhesive layer 72. The constituent material of the seventh base material 71 is not particularly limited as long as it can properly function in a desired process such as a dicing process.

The thickness of the seventh base material 71 is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more.
The thickness of the seventh base material 71 is preferably 100 μm or less, more preferably 75 μm or less, and further preferably 50 μm or less.

As the seventh base material 71, for example, a sheet material such as a synthetic resin film can be used. Examples of the synthetic resin film include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film. , Polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, and polyimide film Etc. In addition, examples of the seventh base material 71 include these crosslinked films and laminated films.

The seventh base material 71 preferably contains a polyester resin, and more preferably comprises a material containing a polyester resin as a main component. In the present specification, the material containing a polyester resin as a main component means that the mass ratio of the polyester resin to the mass of the entire material constituting the substrate is 50 mass% or more.
The polyester resin is, for example, any resin selected from the group consisting of polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, and copolymer resin of these resins. Are preferred, and polyethylene terephthalate resin is more preferred.
As the seventh substrate 71, a polyethylene terephthalate film and a polyethylene naphthalate film are preferable, and a polyethylene terephthalate film is more preferable. The oligomer contained in the polyester film is derived from polyester-forming monomers, dimers, trimers and the like.

-Seventh Adhesive Layer The constituent material of the seventh adhesive layer 72 is not particularly limited as long as it can properly function in a desired process such as a dicing process.
In the present embodiment, the seventh pressure-sensitive adhesive layer 72 is, for example, at least one pressure-sensitive adhesive selected from the group consisting of acrylic pressure-sensitive adhesive, urethane pressure-sensitive adhesive, polyester pressure-sensitive adhesive, rubber pressure-sensitive adhesive and silicone pressure-sensitive adhesive. It is preferable to be composed of an agent, and more preferable to be composed of an acrylic adhesive.

The seventh pressure-sensitive adhesive layer 72 in this embodiment preferably contains a pressure-sensitive adhesive composition. This pressure-sensitive adhesive composition preferably contains an acrylic copolymer containing 2-ethylhexyl acrylate as a main monomer. In the present specification, the term "2-ethylhexyl acrylate as a main monomer" means that the mass ratio of the copolymer component derived from 2-ethylhexyl acrylate to the total mass of the acrylic copolymer is 50% by mass or more. Means In the present embodiment, the proportion of the copolymer component derived from 2-ethylhexyl acrylate in the acrylic copolymer is preferably 50% by mass or more and 95% by mass or less, and 60% by mass or more and 95% by mass. % Or less, more preferably 80% by mass or more and 95% by mass or less, still more preferably 85% by mass or more and 93% by mass or less.

The kind and number of copolymer components other than 2-ethylhexyl acrylate in the acrylic copolymer are not particularly limited. For example, a functional group-containing monomer having a reactive functional group is preferable as the second copolymer component. When the crosslinking agent described below is used, the reactive functional group of the second copolymer component is preferably a functional group capable of reacting with the crosslinking agent. This reactive functional group is preferably, for example, at least one substituent selected from the group consisting of a carboxy group, a hydroxyl group, an amino group, a substituted amino group, and an epoxy group, and at least one of a carboxy group and a hydroxyl group. It is more preferable that it is a substituent, and it is still more preferable that it is a carboxy group.

Examples of the monomer having a carboxy group (carboxy group-containing monomer) include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among the carboxyl group-containing monomers, acrylic acid is preferable from the viewpoint of reactivity and copolymerizability. As the carboxy group-containing monomer, one type may be used alone, or two or more types may be used in combination.

Examples of the monomer having a hydroxyl group (hydroxyl group-containing monomer) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and (meth)acrylic acid 2 -Hydroxybutyl, 3-hydroxybutyl (meth)acrylate, and hydroxyalkyl (meth)acrylates such as 4-hydroxybutyl (meth)acrylate. Among the hydroxyl group-containing monomers, 2-hydroxyethyl (meth)acrylate is preferable from the viewpoint of reactivity of hydroxyl group and copolymerizability. As the hydroxyl group-containing monomer, one type may be used alone, or two or more types may be used in combination.

Examples of acrylic acid ester having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

Other examples of the copolymer component in the acrylic copolymer include (meth)acrylic acid alkyl ester whose alkyl group has 2 to 20 carbon atoms. Examples of alkyl (meth)acrylates include ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, and n-(meth)acrylate. -Hexyl, 2-ethylhexyl methacrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and ( Stearyl (meth)acrylate and the like can be mentioned. Among these (meth)acrylic acid alkyl esters, from the viewpoint of further improving the adhesiveness, a (meth)acrylic acid ester having an alkyl group having 2 to 4 carbon atoms is preferable, and n-butyl (meth)acrylate is more preferable. preferable. The (meth)acrylic acid alkyl ester may be used alone or in combination of two or more.

Other copolymer components in the acrylic copolymer include, for example, alkoxyalkyl group-containing (meth)acrylic acid ester, (meth)acrylic acid ester having an aliphatic ring, and (meth)acrylic acid having an aromatic ring. A copolymer component derived from at least one monomer selected from the group consisting of ester, non-crosslinkable acrylamide, non-crosslinkable (meth)acrylic acid ester having a tertiary amino group, vinyl acetate, and styrene, Can be mentioned.
Examples of the alkoxyalkyl group-containing (meth)acrylic acid ester include methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate. ..
Examples of the (meth)acrylic acid ester having an aliphatic ring include cyclohexyl (meth)acrylate.
Examples of the (meth)acrylic acid ester having an aromatic ring include phenyl (meth)acrylate.
Non-crosslinkable acrylamides include, for example, acrylamide and methacrylamide.
Examples of the non-crosslinkable (meth)acrylic acid ester having a tertiary amino group include (meth)acrylic acid (N,N-dimethylamino)ethyl and (meth)acrylic acid (N,N-dimethylamino) Examples include propyl.
These monomers may be used alone or in combination of two or more.

In the present embodiment, as the second copolymer component, a carboxy group-containing monomer or a hydroxyl group-containing monomer is preferable, and acrylic acid is more preferable. When the acrylic copolymer contains a copolymer component derived from 2-ethylhexyl acrylate and a copolymer component derived from acrylic acid, the copolymer component derived from acrylic acid accounts for the total mass of the acrylic copolymer. The mass ratio is preferably 1% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less. When the proportion of acrylic acid is 1% by mass or less, when the pressure-sensitive adhesive composition contains a crosslinking agent, it is possible to prevent the acrylic copolymer from crosslinking too quickly.

The acrylic copolymer may contain a copolymer component derived from two or more kinds of functional group-containing monomers. For example, the acrylic copolymer may be a ternary copolymer, preferably an acrylic copolymer obtained by copolymerizing 2-ethylhexyl acrylate, a carboxy group-containing monomer and a hydroxyl group-containing monomer, The carboxy group-containing monomer is preferably acrylic acid, and the hydroxyl group-containing monomer is preferably 2-hydroxyethyl acrylate. The proportion of the copolymer component derived from 2-ethylhexyl acrylate in the acrylic copolymer is 80% by mass or more and 95% by mass or less, and the proportion by mass of the copolymer component derived from acrylic acid is 1% by mass or less. And the balance is preferably a copolymer component derived from 2-hydroxyethyl acrylate.

The weight average molecular weight (Mw) of the acrylic copolymer is preferably 300,000 or more and 2 million or less, more preferably 600,000 or more and 1.5 million or less, and 800,000 or more and 1.2 million or less. Is more preferable. When the weight average molecular weight Mw of the acrylic copolymer is 300,000 or more, it can be peeled off without a residue of the adhesive on the adherend. When the weight average molecular weight Mw of the acrylic copolymer is 2,000,000 or less, it can be reliably attached to the adherend.
The weight average molecular weight Mw of the acrylic copolymer is a standard polystyrene conversion value measured by a gel permeation chromatography (GPC) method.

The acrylic copolymer can be produced according to a conventionally known method using the above-mentioned various raw material monomers.

The form of copolymerization of the acrylic copolymer is not particularly limited, and may be a block copolymer, a random copolymer, or a graft copolymer.
In the present embodiment, the content of the acrylic copolymer in the pressure-sensitive adhesive composition is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 90% by mass or less. preferable.

The pressure-sensitive adhesive composition constituting the seventh pressure-sensitive adhesive layer 72 preferably contains at least a pressure-sensitive adhesive obtained by crosslinking a composition further containing a crosslinking agent, in addition to the above-mentioned acrylic copolymer. It is also preferable that the pressure-sensitive adhesive composition substantially consists of a pressure-sensitive adhesive obtained by crosslinking the above-mentioned acrylic copolymer and a crosslinking agent as described above. Here, “substantially” means that the pressure sensitive adhesive is composed of only the pressure sensitive adhesive, except for a trace amount of impurities that are inevitably mixed in the pressure sensitive adhesive.

Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a metal chelate crosslinking agent, an amine crosslinking agent, and an amino resin crosslinking agent. These crosslinking agents may be used alone or in combination of two or more.
From the viewpoint of improving the heat resistance and adhesive strength of the seventh pressure-sensitive adhesive layer 72, among these cross-linking agents, a cross-linking agent (isocyanate-based cross-linking agent) containing a compound having an isocyanate group as a main component is preferable. Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, Polyphenyl isocyanates such as diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate Compounds.
Further, the polyvalent isocyanate compound may be a trimethylolpropane adduct type modified product of the above compound, a buret type modified product reacted with water, or an isocyanurate type modified product having an isocyanurate ring.
In the present specification, the term “crosslinking agent containing a compound having an isocyanate group as a main component” means that the mass ratio of the compound having an isocyanate group to the total mass of the components constituting the crosslinking agent is 50% by mass or more. means.

In the present embodiment, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass with respect to 100 parts by mass of the acrylic copolymer. As described above, the amount is 15 parts by mass or less, more preferably 5 parts by mass or more and 10 parts by mass or less. When the content of the cross-linking agent in the pressure-sensitive adhesive composition is within such a range, the adhesiveness between the seventh pressure-sensitive adhesive layer 72 and the seventh base material 71 can be improved, and the pressure-sensitive adhesive sheet can be adhered after production. The curing period for stabilizing the characteristics can be shortened.

When the pressure-sensitive adhesive composition forming the seventh pressure-sensitive adhesive layer 72 in the present embodiment contains a crosslinking agent, it is preferable that the pressure-sensitive adhesive composition further contains a crosslinking accelerator. It is preferable to appropriately select and use the crosslinking accelerator depending on the type of the crosslinking agent. For example, when the pressure-sensitive adhesive composition contains a polyisocyanate compound as a crosslinking agent, it is preferable that the pressure-sensitive adhesive composition further contains an organometallic compound-based crosslinking accelerator such as an organotin compound.

The pressure-sensitive adhesive composition forming the seventh pressure-sensitive adhesive layer 72 also preferably contains a reactive pressure-sensitive adhesive aid. Examples of the reactive adhesion aid include a polybutadiene resin having a reactive functional group, a hydrogenated product of a polybutadiene resin having a reactive functional group, and the like. As the reactive functional group which the reactive adhesive aid has, one or more functional groups selected from the group consisting of a hydroxyl group, an isocyanate group, an amino group, an oxirane group, an acid anhydride group, an alkoxy group, an acryloyl group and a methacryloyl group. It is preferably a group. When the pressure-sensitive adhesive composition contains a reactive pressure-sensitive adhesive aid, it is possible to reduce adhesive residue when the first pressure-sensitive adhesive sheet 70 is peeled off from the adherend.

In the present embodiment, the pressure-sensitive adhesive composition that constitutes the seventh pressure-sensitive adhesive layer 72 may contain other components as long as the effects of the present invention are not impaired. Other components that may be contained in the pressure-sensitive adhesive composition include, for example, organic solvents, flame retardants, tackifiers, ultraviolet absorbers, antioxidants, antiseptics, antifungal agents, plasticizers, defoamers, and wetting. Examples include sex regulators.

The thickness of the seventh pressure-sensitive adhesive layer 72 is appropriately determined according to the application of the first pressure-sensitive adhesive sheet 70. In the present embodiment, the thickness of the seventh pressure-sensitive adhesive layer 72 is preferably 5 μm or more. The thickness of the seventh pressure-sensitive adhesive layer 72 is preferably 60 μm or less, and more preferably 50 μm or less.
The above is the description regarding the seventh pressure-sensitive adhesive layer 72.

-Release Sheet The first adhesive sheet 70 has a release sheet laminated on the adhesive surface for the purpose of protecting the adhesive surface until the adhesive surface is attached to an adherend (for example, the semiconductor wafer W or the semiconductor chip CP). It may have been done. The configuration of the release sheet is arbitrary, and examples include those obtained by subjecting a plastic film to a release treatment with a release agent or the like. The release sheet may be a release sheet that can be used for the first adhesive sheet 10 and the second adhesive sheet 20.

[Effects of this embodiment]
Even with the expanding method according to the present embodiment, as in the first embodiment, the adhesive sheet structure and process can be simplified as compared with the related art, and adhesive residue can be suppressed. Furthermore, it is possible to provide a method for manufacturing a semiconductor device including the expanding method according to the present embodiment.

In addition, in the expanding method according to the present embodiment, after the back grinding step and before the dicing step, the sticking is performed on the first adhesive sheet 70 that is thinner than the fourth adhesive sheet 40 used in the back grinding step. Are changing. Since the thickness of the pressure-sensitive adhesive sheet cut in the dicing step can be reduced, the load applied to the dicing blade can be reduced.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.
The first embodiment and the third embodiment mainly differ in the following points. In the first embodiment, the back-grinding process is performed and then the dicing process is performed, while in the third embodiment, a so-called pre-dicing method is performed. The front dicing method is a method for obtaining chips by forming grooves of a predetermined depth from the front surface side of a semiconductor wafer, then grinding from the back surface side of the wafer, removing the bottom of the grooves by grinding, and dividing the wafer into individual pieces. ..
In the following description, the part related to the difference from the first embodiment will be mainly described, and the overlapping description will be omitted or simplified. The same components as those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted or simplified.

The expanding method according to this embodiment includes the following steps (PY1) to (PY4) and the same step (P5) as in the first embodiment.
(PY1) A step of adhering an eighth adhesive sheet to the first wafer surface of the wafer before backside grinding.
(PY2) A step of forming a groove having a predetermined depth from the first wafer surface side of the wafer.
(PY3) A step of back-grinding the second wafer surface of the grooved wafer and removing the bottom of the groove to obtain chips.
(PY4) A step of attaching the third adhesive sheet to the eighth adhesive sheet after grinding the back surface of the wafer.
(P5) A step of expanding the third pressure-sensitive adhesive sheet to widen the intervals between the plurality of chips.

[Adhesion process of eighth adhesive sheet]
FIG. 10A is a diagram for explaining the step (PY1). FIG. 10A shows a state in which the eighth adhesive sheet 80 is attached to the circuit surface W1 as the first wafer surface of the semiconductor wafer W before the back surface grinding. The eighth adhesive sheet 80 has an eighth adhesive layer 82 and an eighth base material 81. In the present embodiment, the eighth adhesive sheet 80 is preferably a back grind sheet. As the eighth pressure-sensitive adhesive sheet 80, it is preferable to use the same pressure-sensitive adhesive sheet as the first pressure-sensitive adhesive sheet 10 in the first embodiment or the fourth pressure-sensitive adhesive sheet 40 in the second embodiment as a back-grinding sheet. When the eighth adhesive sheet 80 is used as the back-grinding sheet, the semiconductor wafer W is attached so that the circuit surface W1 faces the eighth adhesive layer 82 of the eighth adhesive sheet 80. The eighth pressure-sensitive adhesive sheet 80 as a back-grinding sheet is preferably attached to the circuit surface W1 as the first wafer surface before the step of forming the groove of the predetermined depth in the semiconductor wafer W.

[Groove forming process]
FIG. 10B is a diagram for explaining the step (PY2). FIG. 10B is a diagram illustrating a step of forming a groove having a predetermined depth from the circuit surface W1 side of the semiconductor wafer W (may be referred to as a groove forming step).
In the groove forming step, a cut is made in the semiconductor wafer from the eighth adhesive sheet 80 side using a dicing blade of a dicing device or the like. At this time, the eighth adhesive sheet 80 is completely cut, and a notch having a depth smaller than the thickness of the semiconductor wafer W is made from the circuit surface W1 of the semiconductor wafer W to form the groove W5. The groove W5 is formed so as to partition the plurality of circuits W2 formed on the circuit surface W1 of the semiconductor wafer W. The depth of the groove W5 is not particularly limited as long as it is slightly deeper than the intended thickness of the semiconductor chip. When forming the groove W5, cutting chips from the semiconductor wafer W are generated. In the present embodiment, since the groove W5 is formed in the state where the circuit surface W1 is protected by the eighth adhesive sheet 80, it is possible to prevent the circuit surface W1 and the circuit W2 from being contaminated or damaged by cutting chips.

[Grinding process]
FIG. 10C is a diagram for explaining the step (PY3). 10C, after forming the groove W5, a step of attaching the third adhesive sheet 30 to the individualized eighth adhesive sheet 80 (adhesion step of the third adhesive sheet), and The figure explaining the process (it may call a grinding process.) of grinding the back surface W6 as a 2nd surface is shown.
In this embodiment, the semiconductor wafer W is ground from the back surface W6 side using the grinder 500. The grinding reduces the thickness of the semiconductor wafer W and finally divides it into a plurality of semiconductor chips CP. Grinding is performed from the back surface W6 side until the bottom of the groove W5 is removed, and the semiconductor wafer W is separated into individual circuits W2. After that, the back surface is further ground as required, and the semiconductor chip CP having a predetermined thickness can be obtained. In this embodiment, grinding is performed until the back surface W3 as the second wafer surface is obtained. The method including the groove forming step and the grinding step of the present embodiment corresponds to the pre-dicing method. In the grinding step of the present embodiment, it is preferable to grind the back surface W6 in a state in which the eighth base material 81 side of the eighth adhesive sheet 80 is supported by a method of fixing with a transfer tape or a vacuum suction plate.

[Step of attaching third adhesive sheet]
FIG. 10D is a diagram for explaining the step (PY4). In FIG. 10D, a step of sticking the third adhesive sheet 30 to the eighth adhesive sheet 80 side of the semiconductor wafer W after the back surface grinding after the grinding step (sometimes referred to as a third adhesive sheet sticking step). .) is illustrated.
As shown in FIG. 10D, a state in which the plurality of divided semiconductor chips CP are held by the eighth adhesive sheet 80 and the third adhesive sheet 30 is shown.

[Expanding process]
In the present embodiment, after the step of adhering the third adhesive sheet in the step (PY4), the third adhesive sheet 30 is expanded and the intervals between the plurality of semiconductor chips CP are expanded in the same manner as in the first embodiment. A process (expanding process: process (P5)) is implemented. Also in this embodiment, it is preferable that the third adhesive sheet 30 is an expanded sheet. The step (P5) in this embodiment can be performed in the same manner as in the first embodiment. Also in the present embodiment, the spacing D1 between the plurality of semiconductor chips CP is preferably the same as that in the first embodiment.

[Effects of this embodiment]
Even with the expanding method according to the present embodiment that employs the first dicing method, the adhesive sheet structure and process can be simplified and the adhesive residue can be suppressed as compared with the related art, as in the first embodiment. Furthermore, it is possible to provide a method for manufacturing a semiconductor device including the expanding method according to the present embodiment.

Further, by using an expanding sheet as the third adhesive sheet 30 used in the grinding step in the present embodiment, the expanding step can be directly carried out after the grinding step, so that the process can be further simplified.

[Modification of Embodiment]
The present invention is in no way limited to the embodiments described above. The present invention includes modes in which the above-described embodiments are modified, etc., within the range in which the object of the present invention can be achieved.

For example, a circuit or the like on a semiconductor wafer or a semiconductor chip is not limited to the illustrated arrangement or shape. The connection structure with the external terminal electrodes in the semiconductor package is not limited to the aspect described in the above embodiment. In the above-described embodiment, the mode of manufacturing the FO-WLP type semiconductor package has been described as an example, but the present invention is also applicable to the mode of manufacturing other semiconductor packages such as the fan-in type WLP.

In the FO-WLP manufacturing method described above, some steps may be changed or some steps may be omitted.

The dicing in the dicing process may be performed by irradiating the semiconductor wafer with laser light instead of using the above cutting means. For example, the semiconductor wafer may be completely divided into a plurality of semiconductor chips by irradiation with laser light. Alternatively, after forming the modified layer inside the semiconductor wafer by irradiating the laser beam, the adhesive sheet is stretched in the expanding step described later to break the semiconductor wafer at the position of the modified layer and separate the semiconductor chip CP into individual chips. It may be separated (stealth dicing. Stealth dicing is a registered trademark). When the process of forming the modified layer on the semiconductor wafer W is adopted, as one aspect, the back grind sheet (for example, the first adhesive sheet 10) is formed together with the formation of the modified layer by the laser beam for forming the modified layer. ) Or a surface protection sheet at the time of dicing (for example, the first pressure-sensitive adhesive sheet 70 of the second embodiment) is singulated. In the case where the process of forming the modified layer on the semiconductor wafer W is adopted, as another aspect, a laser beam for separating the back grinding sheet or the surface protection sheet at the time of dicing is separately irradiated. Separate into individual pieces. In the case of stealth dicing, for example, the laser light is irradiated so that the laser light in the infrared region is focused on a focus set inside the semiconductor wafer. In addition, in these methods, the laser light irradiation may be performed from either side of the semiconductor wafer.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

(Preparation of adhesive sheet)
[Example 1]
62 parts by mass of butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA) were copolymerized to obtain an acrylic copolymer. 2-isocyanatoethylmethacrylate (manufactured by Showa Denko KK, product name "Karenzu MOI" (registered trademark)) is added to this acrylic copolymer solution of resin (acrylic A) (adhesive base, solid Min 35.0% by weight) was prepared. The addition rate was 90 mol% of 2-isocyanatoethyl methacrylate with respect to 100 mol% of 2HEA of the acrylic copolymer.
The weight average molecular weight (Mw) of the obtained resin (acrylic A) was 600,000, and Mw/Mn was 4.5. The weight average molecular weight Mw and the number average molecular weight Mn in terms of standard polystyrene were measured by gel permeation chromatography (GPC) method, and the molecular weight distribution (Mw/Mn) was determined from the respective measured values.
UV resin A (10-functional urethane acrylate, manufactured by Mitsubishi Chemical Corporation, product name "UV-5806", Mw=1740, including a photopolymerization initiator) is contained in the adhesive main agent, and tolylene diisocyanate as a cross-linking agent. A system crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "Coronate L") was added. 50 parts by mass of the UV resin A and 0.2 part by mass of the crosslinking agent were added to 100 parts by mass of the solid content in the adhesive main agent. After the addition, the mixture was stirred for 30 minutes to prepare pressure-sensitive adhesive composition A1.
Next, the prepared solution of the pressure-sensitive adhesive composition A1 was applied to a polyethylene terephthalate (PET)-based release film (manufactured by Lintec Co., Ltd., product name “SP-PET381031”, thickness 38 μm) and dried to give an adhesive having a thickness of 40 μm. The agent layer was formed on the release film.
After sticking a polyester-based polyurethane elastomer sheet (manufactured by Seadam Co., Ltd., product name “High-Grease DUS202”, thickness 100 μm) as a base material to the pressure-sensitive adhesive layer, unnecessary portions at the ends in the width direction are cut and removed. To produce an adhesive sheet SA1.

(Measurement method of chip interval)
The pressure-sensitive adhesive sheet obtained in Example 1 was cut into 210 mm×210 mm to obtain a test sheet. At this time, each side of the sheet after cutting was cut so as to be parallel or perpendicular to the MD direction of the base material in the adhesive sheet.
A semiconductor chip to be attached to the adhesive sheet was prepared by the procedure shown below. A back grind sheet (manufactured by Lintec Corporation, product name "E-3125KL") was attached to a 6-inch silicon wafer. Next, a 6-inch silicon wafer is diced from the back grind sheet side, and a total of 25 chips are arranged so that chips of 3 mm×3 mm size are arranged in 5 rows in the X-axis direction and 5 rows in the Y-axis direction. I cut it out. A dicing back-grinding sheet was attached to each of the chips.
The release film of the test sheet was peeled off, and the back grind sheet side of a total of 25 chips cut out as described above was attached to the center of the exposed adhesive layer. At this time, the chips were arranged in five rows in the X-axis direction and five rows in the Y-axis direction.

Next, the test sheet with the chips attached was installed in a biaxially stretchable expander (separator). FIG. 11 is a plan view illustrating the expanding device 100. In FIG. 11, the X axis and the Y axis are orthogonal to each other, and the positive direction of the X axis is the +X axis direction, the negative direction of the X axis is the −X axis direction, and the positive direction of the Y axis. Is the +Y axis direction, and the negative direction of the Y axis is the −Y axis direction. The test sheet 200 was installed in the expanding device 100 so that each side was parallel to the X axis or the Y axis. As a result, the MD direction of the base material in the test sheet 200 is parallel to the X axis or the Y axis. Note that the chip is omitted in FIG.

As shown in FIG. 11, the expanding device 100 includes five holding means 101 (20 holding means 101 in total) in each of the +X axis direction, the −X axis direction, the +Y axis direction, and the −Y axis direction. Of the five holding means 101 in each direction, the holding means 101A is located at both ends, the holding means 101C is located in the center, and the holding means 101B is located between the holding means 101A and the holding means 101C. Each side of the test sheet 200 was held by these holding means 101.

Here, as shown in FIG. 11, one side of the test sheet 200 is 210 mm. The distance between the holding means 101 on each side is 40 mm. Further, the distance between the end portion (vertex of the sheet) on one side of the test sheet 200 and the holding means 101A existing on the side and closest to the end portion is 25 mm.

Subsequently, a plurality of tension applying means (not shown) corresponding to each of the holding means 101 were driven to move the holding means 101 independently. The four sides of the test sheet were gripped and fixed with a jig, and the test sheet was expanded in the X-axis direction and the Y-axis direction at a speed of 5 mm/s and an expansion amount of 200 mm. Then, the expanded state of the test sheet 200 was held by the ring frame.
While maintaining the expanded state, the distance between the chips was measured with a digital microscope, and the average value of the distances between the chips was taken as the chip interval.
If the chip interval was 1800 μm or more, it was judged as pass “A”, and if the chip interval was less than 1800 μm, it was judged as fail “B”.

(Method of measuring chip alignment)
The deviation rate from the center line of the adjacent chips in the X-axis and Y-axis directions of the work for measuring the chip interval was measured.
FIG. 12 shows a schematic diagram of a specific measuring method.
One row in which five chips were arranged in the X-axis direction was selected, and the distance Dy between the top end of the chip and the bottom end of the chip in the row was measured with a digital microscope. The deviation rate in the Y-axis direction was calculated based on the following mathematical formula (Equation 3). Sy is a chip size in the Y-axis direction and is 3 mm in this embodiment.
Deviation rate in the Y-axis direction [%]=[(Dy−Sy)/2]/Sy×100... (Equation 3)
The deviation rate in the Y-axis direction was calculated in the same manner for the other four rows in which five chips were arranged in the X-axis direction.
One row in which five chips were arranged in the Y-axis direction was selected, and the distance Dx between the leftmost edge of the chip and the rightmost edge of the chip in the row was measured with a digital microscope. The deviation rate in the X-axis direction was calculated based on the following mathematical formula (Equation 4). Sx is a chip size in the X-axis direction, and is 3 mm in this embodiment.
Deviation rate in the X-axis direction [%]=[(Dx−Sx)/2]/Sx×100... (Equation 4)
The misalignment rate in the X-axis direction was calculated in the same manner for the other four rows in which five chips were arranged in the Y-axis direction.
In the mathematical expressions (Equation 3) and (Equation 4), the reason for dividing by 2 is to express the maximum distance deviated from the predetermined position of the expanded chip as an absolute value.
In all the rows in the X-axis direction and the Y-axis direction (total of 10 rows), if the deviation rate is less than ±10%, it is judged as a passing “A”, and if it is ±10% or more in one or more rows, it is not. It was judged to have passed "B".

(Evaluation method of adhesive residue)
After expanding under the conditions described in the method for measuring the chip interval, the chips of the pressure-sensitive adhesive sheet according to Example 1 are mounted using an ultraviolet irradiation device (“RAD-2000 m/12” manufactured by Lintec Co., Ltd.). UV irradiation was performed from the surface opposite to the surface under the conditions of an illuminance of 220 mW/cm ² and a light amount of 460 mJ/cm ² . After the ultraviolet irradiation, the chip was held on the adsorption table and the adhesive sheet was peeled off. After peeling off the pressure-sensitive adhesive sheet, the chip surface to which the pressure-sensitive adhesive sheet was attached was observed with an optical microscope. The case where no adhesive residue was observed on the chip surface was judged as a pass "A", and the case where adhesive residue was observed was judged as a failure "B".

When the pressure-sensitive adhesive sheet according to Example 1 was expanded, the evaluation result of the chip interval was a pass “A” judgment, and the evaluation result of the chip alignment was a pass “A” judgment.
When the pressure-sensitive adhesive sheet was expanded with the back grinding sheet interposed between the chip and the pressure-sensitive adhesive sheet according to the example, the adhesive residue evaluation result on the chip surface was a pass “A” judgment.

10... 1st adhesive sheet, 11... 1st base material, 12... 1st adhesive layer, 20... 2nd adhesive sheet, 21... 2nd base material, 22... 2nd adhesive layer, 30... 3rd adhesive sheet , 31... Third base material, 32... Third adhesive layer, 40... Fourth adhesive sheet, 41... Fourth base material, 42... Fourth adhesive layer, 70... First adhesive sheet, 71... Seventh group Material, 72... Seventh adhesive layer, CP... Semiconductor chip, W... Semiconductor wafer (wafer), W1... Circuit surface (first wafer surface), W2... Circuit, W3... Back surface (second wafer surface).

Claims

A first adhesive sheet having a first adhesive layer and a first base material is attached to the first wafer surface of a wafer having a first wafer surface and a second wafer surface opposite to the first wafer surface. A second adhesive sheet having a second adhesive layer and a second base material is attached to the second wafer surface,
A cut is made from the side of the first adhesive sheet, the first adhesive sheet is cut, and the wafer is divided into a plurality of chips,
Attaching a third pressure-sensitive adhesive sheet having a third pressure-sensitive adhesive layer and a third base material to the first base material,
Peeling the second adhesive sheet from the second wafer surface of the wafer,
Stretching the third pressure-sensitive adhesive sheet to widen the intervals between the plurality of chips;
Expanding method.
In the expanding method according to claim 1,
The cut is formed with a depth from the side of the first adhesive sheet to reach the second adhesive sheet,
Expanding method.
In the expanding method according to claim 1 or 2,
The second wafer surface is a surface formed by grinding the back surface of the wafer,
Expanding method.
In the expanding method according to claim 3,
The first adhesive sheet is adhered to the first wafer surface before back grinding the wafer.
Expanding method.
In the expanding method according to claim 3,
A fourth adhesive sheet is attached to the surface of the first wafer before back grinding the wafer.
Peeling the fourth adhesive sheet from the first wafer surface after backside grinding,
Attaching the first adhesive sheet to the first wafer surface,
Expanding method.
The expanding method according to claim 5,
The fourth adhesive sheet is a back grind sheet,
The first adhesive sheet is a surface protection sheet,
The thickness of the surface protective sheet is 5 μm or more and 500 μm or less,
Expanding method.
In the expanding method according to any one of claims 1 to 6,
The first adhesive sheet is a back grind sheet,
Expanding method.
The expanding method according to any one of claims 1 to 7,
The third adhesive sheet is an expanded sheet,
Expanding method.
In the expanding method according to any one of claims 1 to 8,
The wafer is a semiconductor wafer,
Expanding method.
The expanding method according to any one of claims 1 to 9,
The first wafer surface has a circuit,
Expanding method.
A method for manufacturing a semiconductor device, including the expanding method according to claim 1.