JP7640675B2 - Wafer Processing Method - Google Patents

Description

The present invention relates to a wafer processing method in which the wafer is processed while being fixed to a support via a temporary fixing material, and more specifically, to a processing method in which the introduction of a support improves the handleability of the wafer, making it possible to use the wafer in a wide variety of processing processes, while at the same time enabling the wafer to be stably separated by a relatively simple process such as mechanical peeling.

In semiconductor manufacturing processes, temporary fixing is often necessary or desirable for wafer processing due to the thinness and fragility of the wafer. For example, thin grinding of wafers on which functional layers for semiconductor devices are formed is widely performed for the high integration of semiconductor devices. However, when the wafer is ground to an extremely thin thickness, it cannot be supported by tape alone. It has been proposed to temporarily fix the wafer to a hard carrier (support) via a temporary fixing material and perform processing after thin grinding. A semiconductor manufacturing process using such a support is called a wafer support system.
As a method for peeling off the support after processing, a method that utilizes gas generation from the temporary fixing material (see, for example, Patent Document 1), a peeling method that uses a laser, a peeling method in which the resin of the temporary fixing material is melted and the carrier is slid off, and a method in which the carrier is lifted from one end and peeled off (mechanical peeling), etc. have been proposed.
The mechanical peeling method is a method with excellent cost merits because the equipment is relatively simple. However, in principle, the mechanical peeling method applies a peeling force at least to the wafer/temporary bonding material interface and the temporary bonding material/support interface, and it is not necessarily easy to stably peel at a desired interface. If peeling occurs at an unintended interface (e.g., the wafer/temporary bonding material interface), problems such as damage to the support or electronic components may occur when the support is peeled off.
On the other hand, the adhesive strength at unintended interfaces can be increased to prevent peeling from unintended interfaces during mechanical peeling. However, if the adhesive strength is increased too much, it becomes difficult to peel the temporary bonding material from the wafer, for example.

International Publication No. 2014/024861 A1 Pamphlet

In view of the above technical background, the object of the present invention is to provide a processing method for wafers in a stacked state in which the wafers are fixed to a support via a temporary fixing material, and which can stably separate the wafers from the stack using a relatively simple process such as mechanical peeling.

As a result of extensive investigations, the inventors have discovered that in a wafer processing method in which processing is performed in the state of a laminate in which the wafer is fixed to a support via a temporary bonding material, when the peel strength between the support/temporary bonding material and the peel strength between the temporary bonding material/wafer, measured under specific conditions, satisfy specific conditions, the wafer can be stably separated from the laminate by a relatively simple process such as mechanical peeling, and have completed the present invention.
That is, the present invention provides:
[1]
A step (1) of stacking a support (A), a temporary fixing material (B), and a wafer (C) located on the side of the temporary fixing material (B) opposite to the support (A);
A step (2) of subjecting the wafer (C) to at least one treatment selected from a heat treatment, a mechanical processing treatment, a wet processing treatment, and a laser processing treatment; and a step (3) of separating the wafer (C) from a laminate (D) having the wafer (C) after the treatment.
A method for processing a wafer, comprising:
the ratio of the 10° peel strength P1 between the support (A)/the temporary fixing material (B) to the 10° peel strength _P2 between the temporary fixing material (B)/the wafer (C), _P2 / _P1 , measured while _maintaining the angle between the peeled layers at 10°, is 1.1 or more;
Regarding.

Below, [2] to [14] are each a preferred aspect or embodiment of the present invention.
[2]
The method for treating a wafer according to [1], wherein the peel strength _P1 is 10 N/25 mm or less.
[3]
The method for treating a wafer according to [1] or [2], wherein the temporary bonding material (B) has a different composition between the adhesive layer in contact with the support (A) and the adhesive layer in contact with the wafer (C).
[4]
The method for treating a wafer according to any one of [1] to [3], wherein separation of the wafer (C) from the laminate (D) is achieved by separating the support (A) from the temporary bonding material (B) and then removing the temporary bonding material (B) remaining on the wafer (C).
[5]
The method for treating a wafer according to [4], wherein the method for separating the temporary bonding material (B) and the support (A) is mechanical peeling.
[6]
The method for treating a wafer according to any one of [1] to [5], wherein the temporary bonding material (B) contains a curable adhesive component.
[7]
The method for treating a wafer according to any one of [1] to [5], wherein the temporary bonding material (B) contains a release agent.
[8]
The method for treating a wafer according to any one of [1] to [7], wherein the temporary bonding material (B) is a base film (B ₀ ) having a pressure-sensitive adhesive material laminated on both sides thereof.
[9]
The method for treating a wafer according to any one of [1] to [8], wherein an electrode is formed on the wafer (C).
[10]
The method for treating a wafer according to any one of [1] to [9], wherein in the step (2), a surface of the wafer (C) on which no electrode is formed is ground.
[11]
The method for treating a wafer according to [10], wherein the thickness of the wafer (C) after grinding is 1 μm or more and 200 μm or less.
[12]
A method for manufacturing an electronic device, comprising carrying out the wafer processing method according to any one of [1] to [11].
[13]
The method for producing an electronic device according to [12], wherein the electronic device has a structure in which semiconductor chips are stacked.
[14]
A laminate (D) in which a support (A), a temporary fixing material (B), and a wafer (C) located on a side of the temporary fixing material (B) opposite to the support (A),
A laminate in which the ratio P2/P1 of the 10° peel strength _P1 between the support (A) and the temporary fixing material (B) to the 10° peel strength P2 between the temporary fixing material (B ₎ and the wafer (C), measured while _maintaining the angle between the peeled layers at 10°, is 1.1 or _more .

According to the wafer processing method of the present invention, the handleability of thin or fragile wafers is improved, the wafers can be stably processed in a wide range of processing processes, unintended peeling at the interface is effectively suppressed, and the processed wafers can be stably separated and removed using a relatively simple and low-cost process such as mechanical peeling. This makes it possible to perform multiple and/or diverse processes on the wafer with high productivity and yield without damaging electronic components such as functional layers formed on the wafer, greatly contributing to improving the productivity of electronic components such as electronic devices.

FIG. 2 is a schematic diagram illustrating mechanical peeling in one embodiment of the present invention. FIG. 1 is a schematic diagram illustrating separation of a support (A) from a laminate (D) in one embodiment of the present invention, where (a) shows a preferred separation form, and (b) to (c) show unpreferred separation forms. 1 is a schematic diagram for explaining a method for measuring a 10° peel strength specified in the present invention, in which (a) shows a case where a measurement sample for 10° peel strength _P1 is used, in which a pressure _- sensitive adhesive layer (B ₁ ) on the side in contact with a support (A) is laminated onto a base film (B ₀ ); (b) shows a case where a measurement sample for 10° peel strength _P2 is used, in which a pressure-sensitive adhesive layer (B ₂ ) on the side in contact with a wafer (C) is laminated onto a base film (B ₀ ); (c) shows a case where a measurement sample is prepared by laminating a polyimide film onto a temporary fixing material (B) having no base film (B 0 ) and the 10° peel strength _P1 is measured; and (d) shows a case where a measurement sample is prepared by laminating a polyimide film onto a temporary fixing material (B) having no base film (B ₀ ) and the 10° peel strength _P2 is measured. FIG. 2 is a schematic diagram showing a method for evaluating the removability of a temporary bonding material (B) from a wafer (C) in one embodiment of the present invention. FIG. 2 is a schematic diagram showing a laminate (D) in one embodiment of the present invention. FIG. 2 is a schematic diagram showing a laminate (D) in another embodiment of the present invention.

The present invention relates to
A step (1) of stacking a support (A), a temporary fixing material (B), and a wafer (C) located on the side of the temporary fixing material (B) opposite to the support (A);
A step (2) of subjecting the wafer (C) to at least one treatment selected from a heat treatment, a mechanical processing treatment, a wet processing treatment, and a laser processing treatment; and a step (3) of separating the wafer (C) from a laminate (D) having the wafer (C) after the treatment.
A method for processing a wafer, comprising:
the ratio of the 10° peel strength P1 between the support (A)/the temporary fixing material (B) to the 10° peel strength _P2 between the temporary fixing material (B)/the wafer (C), _P2 / _P1 , measured while _maintaining the angle between the peeled layers at 10°, is 1.1 or more;
It is.
That is, in the processing method of the present invention, a support (A) and a temporary bonding material (B) serving as a temporary bonding material are used in processing a wafer (C).

Support (A)
The support (A) is preferably one having sufficient strength and rigidity, and excellent heat resistance and chemical resistance. By using such a support (A), even if the wafer (C) is thin-ground, the wafer (C) can be stably handled, and the wafer (C) can be subjected to a large number and/or a wide variety of processes without bending or the like. For example, the wafer (C) on which an electronic circuit is formed can be subjected to various processes required for manufacturing an electronic device having a structure in which semiconductor chips are stacked, such as TSV connection.
Materials preferably used for the support (A) include silicon, sapphire, quartz, metals (e.g., aluminum, copper, steel), and various glasses and ceramics. The support (A) may be composed of a single material, but may also be composed of multiple materials, and may include other materials deposited on the substrate. For example, the support (A) may have a vapor deposition layer such as silicon nitride on a silicon wafer.
In order to adjust the 10° peel strength _P1 between the temporary fixing material (B) and the adhesive, the adhesive may be surface-treated, for example by providing a silicone layer.

Depending on the temperature of the process to which the laminate (D) is subjected, the support (A) may be made of plastic. For example, a sheet made of a plastic such as polyimide, acrylic, polyolefin, polycarbonate, vinyl chloride, ABS, polyethylene terephthalate (PET), nylon, or urethane can be preferably used as the support (A). It is particularly preferable to use polyimide because it has a certain degree of heat resistance.

It is desirable that the thickness of the support (A) is uniform in order to obtain uniformity in the thickness of the wafer (C) after grinding, etc. For example, in order to thin a silicon wafer to 50 μm or less with a uniformity of ±10% or less, the variation in the thickness of the support (A) should be suppressed to ±2 μm or less.
The thickness of the support (A) is not particularly limited, but from the viewpoint of effectively preventing the warping of the wafer (C), it is preferably 300 μm or more, and particularly preferably 500 μm or more, and from the viewpoint of suppressing the total weight during handling or reducing the stress required for mechanical peeling, it is preferably 1500 μm or less, and particularly preferably 1000 μm or less.

Temporary fixing material (B)
The temporary fixing material (B) is used to fix the wafer (C) to the support (A).
It is preferable that the temporary fixing material (B) can be easily peeled off from the support (A) and the wafer (C). Therefore, it is preferable that the temporary fixing material (B) has a sufficient adhesive strength to fix the wafer (C) to the support (A) but has a sufficiently low adhesive strength so that it can be peeled off.

It is preferable to use a pressure-sensitive adhesive material for the temporary fixing material (B), and examples of pressure-sensitive adhesive materials used in such embodiments include rubber-based, acrylic-based, epoxy-based, urethane-based, allyl-based, silicone-based, fluorine-based, and polyimide-based pressure-sensitive adhesive materials. Of these, acrylic-based or silicone-based pressure-sensitive adhesive materials are preferred because they are heat-resistant and the adhesive strength and adhesion can be easily adjusted.

The adhesive material may be either a curable adhesive material or a non-curable adhesive material, but it is preferable to use a curable adhesive material, since curing it before heat treatment makes it less likely that voids will occur during heat treatment in the manufacturing process, and suppresses adhesion buildup due to high temperatures during heat treatment, making it easier to peel off without leaving any glue residue.

Examples of the curable adhesive include photocurable adhesives that are crosslinked and cured by irradiation with light, and thermosetting adhesives that are crosslinked and cured by heating.
Examples of the photocurable adhesive material and thermosetting adhesive material include photocurable adhesive materials and thermosetting adhesive materials that contain a monomer, oligomer, or polymer such as acrylic, epoxy, urethane acrylate, epoxy acrylate, silicone acrylate, or polyester acrylate as a curing component and contain a photopolymerization initiator or a thermal polymerization initiator.

Of the above, the acrylic adhesive polymer can be obtained, for example, by synthesizing in advance a (meth)acrylic polymer having a functional group in the molecule (hereinafter referred to as a functional group-containing (meth)acrylic polymer), and reacting it with a compound having in the molecule a functional group that reacts with the functional group and a radically polymerizable unsaturated bond (hereinafter referred to as a functional group-containing unsaturated compound).

The functional group-containing (meth)acrylic polymer is obtained by copolymerizing, in a conventional manner, an acrylic acid alkyl ester and/or a methacrylic acid alkyl ester, the alkyl group of which typically has 2 to 18 carbon atoms, with a functional group-containing monomer and, if necessary, with other modifying monomers that are copolymerizable with the functional group-containing monomer. The weight-average molecular weight of the functional group-containing (meth)acrylic polymer is typically about 200,000 to 2,000,000.

Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid and methacrylic acid, hydroxyl group-containing monomers such as hydroxyethyl acrylate and hydroxyethyl methacrylate, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, isocyanate group-containing monomers such as isocyanate ethyl acrylate and isocyanate ethyl methacrylate, and amino group-containing monomers such as aminoethyl acrylate and aminoethyl methacrylate.

Other copolymerizable modifying monomers include, for example, various monomers used in general (meth)acrylic polymers, such as vinyl acetate, acrylonitrile, and styrene.

As the functional group-containing unsaturated compound to be reacted with the functional group-containing (meth)acrylic polymer, the same as the functional group-containing monomer described above can be used depending on the functional group of the functional group-containing (meth)acrylic polymer. For example, when the functional group of the functional group-containing (meth)acrylic polymer is a carboxyl group, an epoxy group-containing monomer or an isocyanate group-containing monomer is used. When the functional group is a hydroxyl group, an isocyanate group-containing monomer is used. When the functional group is an epoxy group, a carboxyl group-containing monomer or an amide group-containing monomer such as acrylamide is used. When the functional group is an amino group, an epoxy group-containing monomer is used.

Examples of the photopolymerization initiator include those that are activated by irradiation with light having a wavelength of 250 to 800 nm. Examples of such photopolymerization initiators include acetophenone derivative compounds such as methoxyacetophenone, benzoin ether compounds such as benzoin propyl ether and benzoin isobutyl ether, ketal derivative compounds such as benzyl dimethyl ketal and acetophenone diethyl ketal, phosphine oxide derivative compounds, bis(η5-cyclopentadienyl) titanocene derivative compounds, benzophenone, Michler's ketone, chlorothioxanthone, todecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexyl phenyl ketone, and photoradical polymerization initiators such as 2-hydroxymethylphenylpropane. These photopolymerization initiators may be used alone or in combination of two or more.

The thermal polymerization initiator may be one that decomposes by heat to generate active radicals that initiate polymerization and curing. Specific examples of the thermal polymerization initiator include t-butylperoxy-2-ethyl hexanoate, bis(4-methylbenzoyl)peroxide, benzoyl peroxide, 1,1-bis(t-hexylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(4,4-bis-(t-butylperoxy)cyclohexyl)propane, t-hexylperoxyisopropyl monocarboxylate, t-butylperoxyacetate, 2,2-bis-( t-butylperoxy)butane, n-butyl 4,4-bis-(t-butylperoxy)pentanoate, bis-t-hexyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, bis(2-t-butylperoxyisopropyl)benzene, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne, and diisopropylbenzene hydroperoxide.
Among these thermal polymerization initiators, commercially available ones are not particularly limited, but suitable examples include Perbutyl O, Niper BMT, Niper BW, Perhexa HC, Perhexa C, Pertetra A, Perhexyl I, Perbutyl A, Perhexa 22, Perhexa V, Perhexyl D, Percumyl D, Perhexa 25B, Perbutyl P, Perbutyl C, Perhexyne 25B, Percumyl P (all manufactured by NOF Corp.), Perkadox 12XL25 (manufactured by Noury Chemical Co., Ltd.), etc. These thermal polymerization initiators may be used alone or in combination of two or more kinds.

The oligomer or monomer used as the curing component generally has a molecular weight of 10,000 or less and has 1 to 40 radically polymerizable unsaturated bonds in the molecule. From the viewpoint of three-dimensional reticulation, it is preferable that the number of radically polymerizable unsaturated bonds is 2 or more.

Examples of the oligomer or monomer as the curing component include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, and the same methacrylates as those mentioned above. Other examples include 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, commercially available oligoester acrylates, urethane acrylates, and the same methacrylates as those mentioned above. These polyfunctional oligomers or monomers may be used alone or in combination of two or more.

If desired, the temporary fixing material (B) may contain known additives such as an acrylic polymer having no unsaturated double bonds, various thermal crosslinking agents such as isocyanate compounds, melamine compounds, and epoxy compounds, and release agents, plasticizers, resins, surfactants, waxes, and particulate fillers.

In the temporary bonding material (B), it is preferable to use a release agent from the viewpoint of adjusting the peel strength with the support (A) and/or the wafer (C).
The release agent is not particularly limited as long as it generally exhibits a release effect. For example, hydrocarbon compounds, silicone compounds, fluorine compounds, polyethylene wax, carnauba wax, montanic acid, stearic acid, etc., which are known as release agents for plastic materials, can be mentioned. Among them, silicone and fluorine compounds are preferred, and silicone and fluorine compounds having a functional group capable of crosslinking with the curable adhesive are more preferred.
In particular, silicone compounds have excellent heat resistance, so they prevent the adhesive from burning even after treatment involving heating at 200°C or higher, and when peeled off, they bleed out to the interface with the adherend, making it easy to peel off. Since the silicone compound has a functional group that can crosslink with the curing adhesive, it reacts chemically with the curing adhesive by irradiation with light or heating and is incorporated into the curing adhesive, so the silicone compound does not adhere to the adherend and contaminate it. In addition, the incorporation of the silicone compound also has the effect of preventing glue from remaining on the semiconductor chip.
Other examples of the release agent include plasticizers. The plasticizer is not particularly limited as long as it generally reduces the adhesive strength of the adhesive material to the adherend. Examples of the plasticizer include trimellitic acid esters, pyromellitic acid esters, phthalic acid esters, and adipic acid esters.

The amount of release agent added is not particularly limited, but is appropriately determined so as to obtain a release effect. On the other hand, the amount added is controlled so as not to be excessive so as not to significantly impair the adhesive function of the temporary fixing material (B). For example, it is desirable to adjust the amount according to the peel force, aiming at an amount of usually 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and more preferably 0.1 to 1 part by weight, per 100 parts by weight of the temporary fixing material (B).

When a plasticizer is added, it is desirable to adjust the amount of the plasticizer according to the peel strength, usually about 5 to 50 parts by weight, preferably about 10 to 50 parts by weight, and more preferably about 20 to 40 parts by weight.
In this embodiment, these release agents can be used alone or in combination.

The thickness of the temporary fixing material (B) is not particularly limited, but the preferred lower limit is 5 μm and the preferred upper limit is 250 μm, and the more preferred lower limit of the thickness of the temporary fixing material (B) is 10 μm and the more preferred upper limit is 200 μm. If the thickness of the temporary fixing material (B) is within this range, it can absorb the unevenness of the wafer (C) and can be temporarily fixed to the support (A) with sufficient strength, and it is easy to adjust the peeling force to a suitable range when peeling off the temporary fixing material (B).

The temporary bonding material (B) may be a single layer or a laminate of multiple layers.
In the case of a laminate of multiple layers, it is preferable that the layers on the wafer (C) side and the support (A) side are layers having tackiness (tacky adhesive layers). In this case, one of the tacky adhesive layers (B ₁ ) can be configured to have an appropriate peel strength between the support (A), and the other tacky adhesive layer (B ₂ ) can be configured to have an appropriate peel strength between the support (A). In this case, it is preferable that the tacky adhesive layer (B ₁ ) in contact with the support (A) and the tacky adhesive layer (B ₂ ) in contact with the wafer (C) have different compositions. In this case, the tacky adhesive layer (B ₁ ) and the tacky adhesive layer (B ₂ ) may have a layered configuration in the general sense in which the composition changes discontinuously at the interface, but may also have a so-called gradient composition in which the composition changes continuously.
The adhesive layer (B ₁ ) in contact with the support (A) and the adhesive layer (B ₂ ) in contact with the wafer (C) may be directly laminated, but it is preferable that they are laminated on both sides of the support (A) via a base film (B ₀ ), that is, a so-called double-sided adhesive tape. In this embodiment, the adhesive layer (B ₁ ) can be designed from the viewpoint of optimizing the peel strength between the support (A), the adhesive layer (B ₂ ) can be designed from the viewpoint of optimizing the peel strength between the wafer (C), and the base film (B ₀ ) can be designed from the viewpoint of the mechanical strength and handleability of the entire temporary fixing material (B) and the entire laminate (D), and therefore, this is particularly advantageous from the viewpoint of optimizing the performance of the temporary fixing material (B).
An example of a laminate (D) using a temporary fixing material (B) consisting of a tacky adhesive layer (B ₁ ), a base film (B ₀ ), and a tacky adhesive layer (B ₂ ) is shown in Fig. 5. In the figure, 11 indicates a support (A), 20 indicates the tacky adhesive layer (B ₁ ) on the support (A) side, 19 indicates the base film (B ₀ ), 18 indicates the tacky adhesive layer (B ₂ ) on the wafer (C) side, and 13 indicates the wafer (C).
The material of the base film (B ₀ ) is not particularly limited, but it is preferable to use a plastic film, and examples thereof include films, sheets, sheets having a mesh-like structure, and sheets having holes, such as acrylic, olefin, polycarbonate, vinyl chloride, ABS, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, urethane, polyether ether ketone (PEEK), liquid crystal polymer (LCP), and polyimide.

Wafer (C)
There is no particular limitation on the wafer (C) to be processed by the method of the present invention, and any wafer that can be processed in step (2) of the present invention can be used. In particular, the method of the present invention is preferably used for processing wafers that require careful handling due to their thinness and fragility, and therefore require temporary fixing (temporary fixation). Here, the thinness and fragility of the wafer are often brought about in steps (1) and/or (2) described below. For example, the method of the present invention is preferably used for processing wafers whose thickness temporarily becomes thin during processing, causing problems in handling. Examples of cases where a wafer becomes temporarily thin include a case where a thin wafer is processed starting from a thin wafer, a case where a relatively thick wafer is thinned during a process, and a case where the thin wafer is further processed. The thickness of the temporarily thinned wafer (C) is usually 1 to 200 μm.
For example, in a case where a semiconductor wafer on which processing of the functional layer has been completed is temporarily fixed to a carrier with the functional layer facing the carrier, the opposite side (back side) of the functional layer is thinly ground, ions are implanted on the back side, annealing is performed, and electrodes are formed, and the semiconductor wafer during the process corresponds to wafer (C).
As described above, the wafer (C) to be processed in the present invention includes those whose state changes during the process.
As described above, the wafer (C) to be processed by the present invention is not particularly limited. More specific examples thereof include semiconductor wafers such as silicon wafers, compound semiconductor wafers such as SiC, AlSb, AlAs, AlN, AlP, BN, BP, BAs, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, or InP, quartz wafers, sapphire, glass, and mold wafers.
The silicon wafer or compound semiconductor wafer may be doped.

An electric/electronic functional layer may be formed on or in the wafer (C). Suitable examples of the functional layer include electronic circuits, capacitors, transistors, resistors, electrodes, optical elements, MEMS, etc., but may also be other microdevices.
The surfaces of these functional layers may have structures, typically electrodes, formed from one or more of the following materials: silicon, polysilicon, silicon dioxide, (oxy)silicon nitride, metals (e.g., copper, aluminum, gold, tungsten, tantalum), low-k dielectrics, polymer dielectrics, and various metal nitrides and metal silicides. The surface of the wafer (C) on which the functional layers are formed (functional layer surface) may also have raised structures such as solder bumps and metal posts and pillars.

Step (1)
The wafer processing method of the present invention includes a step (1) of stacking the above-mentioned support (A), temporary bonding material (B), and a wafer (C) located on the side of the temporary bonding material (B) opposite to the support (A).
An example of the state after step (1) is shown in Fig. 6. In the figure, 11 denotes a support (A), 12 denotes a temporary bonding material (B), and 13 denotes a wafer (C).
By fixing the wafer (C) to the support plate (A) via the temporary fixing material (B), the wafer (C) can be easily handled when it is processed in the subsequent step (2), and bending or damage can be prevented.

The order in which the support (A), the temporary bonding material (B), and the wafer (C) are laminated is not particularly limited, and these layers may be laminated at once or sequentially.
When the temporary fixing material (B) is supplied as a liquid curable adhesive material or the like, the liquid curable adhesive material or the like can be applied onto either one or both of the wafer (C) and the support (A) by spin coating or the like to form the temporary fixing material (B) or a precursor of the temporary fixing material (B), and then a laminate can be created.
When the temporary fixing material (B) or a precursor of the temporary fixing material (B) is supplied in the form of a solid film, the adhesive strength to the support is usually set lower than that to the wafer side. Therefore, from the viewpoint of preventing peeling during handling, it is preferable to first attach the film onto the wafer (C) and then laminate the support (A).
Furthermore, in the case where the film is attached at normal pressure and only the formation of the laminate is carried out under reduced pressure, from the viewpoint of improving the absorption of unevenness in the wafer, it is preferable to first attach the film-like temporary fixing material onto a support (A) and then attach this to a wafer (C).

In the case where the temporary fixing material (B) or a precursor of the temporary fixing material (B) contains a curable adhesive component, the temporary fixing material (B) may be obtained by performing adhesive curing in which the curable adhesive component is crosslinked and cured by irradiating the curable adhesive component with light or heating in the step (1).
The curable adhesive component crosslinked and cured by irradiation with light or heat has a dramatically improved chemical resistance, and can suppress the adhesive from dissolving in a chemical solution, even if a chemical solution is applied to the back surface of the wafer (C) in step (2). In addition, the crosslinked and cured curable adhesive component has an increased elastic modulus, so that adhesion is less likely to increase even at high temperatures, and peeling is relatively easy.
As described above, in this embodiment, even though the wafer (C) is subjected to heat treatment, mechanical processing, and/or wet processing in step (2), sufficient adhesive strength is maintained during wafer (C) processing, and after completion of the wafer (C) processing step, the wafer (C) can be peeled off from the temporary fixing material (B) in step (3) without being damaged or leaving any adhesive residue.

For example, when a photocurable adhesive component that crosslinks and cures upon irradiation with light is used that contains a polymer having an unsaturated double bond such as a vinyl group in the side chain and a photopolymerization initiator that is activated at a wavelength of 250 to 800 nm, the photocurable adhesive component is preferably irradiated with an illuminance of 5 mW or more, more preferably 10 mW or more, even more preferably 20 mW or more, and particularly preferably 50 mW or more. It is also preferable to irradiate with an integrated illuminance of 300 mJ or more, more preferably 500 mJ or more and 10,000 mJ or less, even more preferably 500 mJ or more and 7,500 mJ or less, and particularly preferably 1,000 mJ or more and 5,000 mJ or less.

In addition, for example, when a thermosetting adhesive component in which the temporary fixing material (B) or a precursor of the temporary fixing material (B) is crosslinked and cured by the above-mentioned heating is a polymer having an unsaturated double bond such as a vinyl group in the side chain and a thermal polymerization initiator that is activated by heating at about 50 to 200°C, the thermosetting adhesive component can be crosslinked and cured by heating at a temperature of about 50 to 200°C for 10 to 60 minutes.

When the precursor of the temporary fixing material (B) is cured to form the temporary fixing material (B) as described above, it may be laminated with the support (A) or the wafer (C) after curing, or it may be cured after lamination, or it may be laminated in a semi-cured state and then finally cured.

Step (2)
The wafer processing method of the present invention then includes a step (2) of subjecting the wafer (C) after the step (1) to at least one treatment selected from a heat treatment, a mechanical processing treatment, a wet processing, and a laser processing treatment.
The above step (2) also includes TSV processing and processing necessary for forming a structure in which TSV-processed semiconductor chips are stacked.
Examples of the heat treatment (including treatment accompanied by heat generation; the same applies below) include sputtering, deposition, etching, chemical vapor deposition (CVD), physical vapor deposition (PVD), resist coating/patterning, heat lamination of a resin composition film, thermal curing of a resin composition, heat drying of a resin composition, baking of a resin composition, reflow, resin sealing, plasma treatment, chip bonding, wire bonding, flip chip bonding, surface activation direct bonding, and the like, but are not limited to these.
The wafer processing method of the present invention can be suitably adapted to temperatures of 100° C., particularly 150° C. or higher, during the above-mentioned steps.

The machining process is typically a polishing, grinding, drilling, cutting process of the wafer, but is not limited to this, and also includes singulation and the like.
When grinding or polishing a wafer (C) having electrodes formed on its surface, the surface on which the electrodes are not formed (back surface) is ground or polished. The thickness of the wafer (C) after grinding and polishing the back surface varies depending on the electronic device in which the obtained electronic device is used, but is usually set to 1 μm or more and 200 μm or less, preferably 5 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less. This allows the obtained electronic device to be made thinner, and the electronic device using the electronic device to be made smaller.

In this embodiment, when grinding and polishing the wafer (C), the wafer (C) is laminated to a rigid support (A) via a temporary fixing material (B), so that the wafer (C) can be ground, etc. with better processing accuracy, and after this grinding, etc., the wafer (C) can be subjected to further processing steps or easily separated from the support (A) and the temporary fixing material (B) without damaging the wafer (C).

The wet treatment is a coating treatment such as spin coating, inkjet, or screen printing, a polishing treatment such as CMP, or a treatment using an acid, an alkali, or an organic solvent. Examples of the wet treatment include plating treatment such as electrolytic plating or electroless plating, wet etching treatment using hydrofluoric acid, an aqueous solution of tetramethylammonium hydroxide (TMAH), or the like, a resist stripping process using N-methyl-2-pyrrolidone, monoethanolamine, DMSO, or the like, and a cleaning process using concentrated sulfuric acid, aqueous ammonia, aqueous hydrogen peroxide, or the like, but are not limited to these.
The above-mentioned laser treatment includes, but is not limited to, annealing, via processing, circuit formation processing by direct writing, and pre-treatment for separation from the support.

In the wafer processing method of the present invention, a dicing tape may be applied to the processed surface (preferably the ground surface) of the wafer after the above processing prior to step (3) described below. By applying the dicing tape in advance, dicing can be performed promptly after peeling off the support (A) and the temporary fixing material (B) in step (3).

In the present invention, the support (A) is separated from the temporary bonding material (B) in the step (3), but a treatment prior to the separation may be carried out in advance in the step (2).
Specifically, a method such as laser treatment, swelling or dissolution of the temporary fixing material (B) with a solvent before mechanical peeling can be appropriately adopted, but it is preferable not to carry out these treatments because it is advantageous in terms of cost since the equipment can be simplified.
In this specification, the laminate having the wafer (C) that has been subjected to the step (2) is also referred to as a laminate (D).

Step (3)
The wafer processing method of the present invention then includes a step (3) of separating the processed wafer (C) from the laminate (D).
The separation of the wafer (C) from the laminate (D) is preferably achieved by separating the support (A) from the laminate (D) and then removing the temporary fixing material (B) remaining on the wafer (C). In this embodiment, when removing the temporary fixing material (B) remaining on the wafer (C), the normally rigid support (A) has already been separated from the laminate (D), so that the wafer (C) can be separated from the temporary fixing material (B) without applying excessive stress to the wafer (C), thereby limiting the risk of damaging the functional layer formed on the wafer (C).
The method for separating the support (A) from the temporary bonding material (B) is not particularly limited, but it is preferable to use mechanical peeling.
Both the separation between the support (A) and the temporary bonding material (B) and the separation between the temporary bonding material (B) and the wafer (C) may be performed by mechanical peeling, or a method other than mechanical peeling may be used for one of them.

In the wafer processing method of the present invention, since the peel strength ratio _P2 / _P1 is 1.1 or more, peeling between the support (A) and the temporary fixing material (B) is relatively easy, and therefore the support (A) can be stably peeled from the laminate (D) over the entire surface of the laminate (D) by a relatively simple process such as mechanical peeling. At this time, peeling at an unintended interface, i.e., between the temporary fixing material (B) and the wafer (C), is effectively suppressed, so the risk of damaging the functional layer formed on the wafer (C) is limited.

In the laminate (D) composed of the support (A)/temporary fixing material (B)/wafer (C) separated in step (3), the ratio P 2 /P 1 between the 10° peel strength P ₁ between the support (A)/temporary fixing material (B) and the 10° peel strength P ₂ between the temporary fixing material (B)/wafer (C), measured while maintaining the angle between the peeled layers at 10°, is 1.1 or more. The 10° peel strength P ₁ between the support (A)/temporary fixing material (B) and _the 10° peel strength P ₂ between the temporary fixing material (B)/wafer (C ₎ are measured values after a history equivalent to that of step (2) described later. For example, when a thermal history of 150 to 200° C. is applied in step (2), the values are values after the thermal history is applied.
According to the wafer processing method of the present invention, since the peel strength ratio _P2 / _P1 is 1.1 or more, the support (A) can be stably peeled from the temporary bonding material (B) over the entire surface of the laminate (D) by a relatively simple process such as mechanical peeling.
At this time, peeling at the unintended interface, i.e., between the temporary bonding material (B) and the wafer (C), is effectively suppressed, so the risk of damaging the functional layer, etc. formed on the wafer (C) is limited.
In addition, the phenomenon in which some of the temporary fixing material (B) remains on the support (A) or some of the temporary fixing material (B) on the wafer (C) is lost is also effectively suppressed, so the risk of uneven stress being applied to the wafer (C) or support (A) and damaging them is also limited.

The 10° peel strength _P1 between the support (A) and the temporary fixing material (B) and the 10° peel strength _P2 between the temporary fixing material (B) and the wafer (C) are the force (N/mm) per width of the peeled portion required to proceed with peeling while maintaining the angle between the peeled layers (support (A) and the temporary fixing material (B), or the temporary fixing material (B) and the wafer (C)) at 10°.
That is, the 10° peel strength _P1 between support (A)/temporary fixing material (B) and the 10° peel strength _P2 between temporary fixing material (B)/wafer (C) can be determined by progressing peeling between 11 support (A)/12 temporary fixing material (B) or between 12 temporary fixing material (B)/13 wafer (C) in the state shown in FIG. 3 or a state equivalent thereto, measuring the force required for peeling, and dividing this by the width of the peeled portion; more specifically, they can be measured by the following method.

The support (A) and the wafer (C) are usually rigid, or usually brittle, and it is usually difficult to maintain the angle between the peeled layers at 10° in the laminate (D) in which the support (A)/temporary fixing material (B)/wafer (C) are laminated. Therefore, when measuring the 10° peel strength _P1 between the support (A)/temporary fixing material (B), a sample for measuring the 10° peel strength _P1 that does not have the wafer (C) is used ( FIGS. 3( a ), ( c )), and when measuring the 10° peel strength _P2 between the temporary fixing material (B)/wafer (C), a sample for measuring the 10° peel strength _P2 that does not have the support (A) can be used ( FIGS. 3( b ), ( d )).
In the former case, when the temporary fixing material (B) has a base film (B ₀ ), a sample for measuring 10° peel strength _P1 is constituted by the support (A) and the temporary fixing material (B) having the base film (B ₀ ), and measurement is performed ( FIG. 3( a )). When the temporary fixing material (B) does not have a base film and is only an adhesive material layer, a polyimide film or the like is backed on the adhesive material layer to constitute a sample for measuring 10° peel strength _P1, and measurement is performed ( FIG. 3( c )).
In the latter case, when the temporary fixing material (B) has a base film (B ₀ ), a sample for measuring 10° peel strength _P2 is constituted by the temporary fixing material (B) having the base film (B ₀ ) and the wafer (C) and measurement is performed ( FIG. 3( b )). When the temporary fixing material (B) does not have a base film and is only an adhesive layer, a polyimide film or the like is backed on the adhesive layer to constitute a sample for measuring 10° peel strength _P2 and measurement is performed ( FIG. 3( d )).

The peel strength ratio P ₂ /P ₁ is preferably 1.1 or more, and particularly preferably 1.3 or more.
There is no particular upper limit to the above peel strength ratio _P2 / _P1 , but from the viewpoint of appropriately peeling the wafer (C) from the temporary fixing material (B), it is desirable that the peel strength _P2 between the temporary fixing material (B)/wafer (C) is not excessively large, and from the viewpoint of stably carrying out the treatment in step (2), particularly the mechanical processing treatment, it is desirable that the 10° peel strength _P1 between the support (A)/temporary fixing material (B) is not too small, so the above peel strength ratio _P2 / _P1 is preferably 30 or less, more preferably 15 or less, and particularly preferably 7 or less.

In step (3), from the viewpoint of stably peeling the support (A) from the temporary fixing material (B) over the entire surface of the laminate (D) in a relatively simple process such as mechanical peeling and without applying excessive stress to the wafer (C), the 10° peel strength _P1 between the support (A)/temporary fixing material (B) is preferably 10 N/25 mm or less.
The 10° peel strength _P1 between the support (A) and the temporary fixing material (B) is more preferably 8 N/25 mm or less, and particularly preferably 7 N/25 mm or less.
From the viewpoint of stably carrying out the treatment in the step (2), particularly the machining treatment, the 10° peel strength _P1 between the support (A) and the temporary fixing material (B) is preferably 1 N/25 mm or more, and more preferably 2 N/25 mm or more.

The separation of the temporary bonding material (B) and the wafer (C) in the step (3) is preferably achieved by separating the support (A) from the laminate (D) and then removing the temporary bonding material (B) remaining on the wafer (C), and from this viewpoint, the 10° peel strength _P2 between the temporary bonding material (B)/wafer (C) is preferably 30 N/25 mm or less, and more preferably 20 N/25 mm or less.
From the viewpoint of stably carrying out the treatment in the step (2), particularly the machining treatment, the 10° peel strength _P2 between the temporary fixing material (B)/wafer (C) is preferably 2 N/25 mm or more, and more preferably 3 N/25 mm or more.

There is no particular limitation on the means for adjusting the above 10° peel strength P ₁ , 10° peel strength P ₂ , and peel strength ratio P ₂ /P _1, but they can be appropriately increased or decreased by, for example, means conventionally used in the technical field. More specifically, they can be appropriately increased or decreased by the composition and manufacturing process of each layer, the manufacturing process of the laminate (D), etc. For example, the 10° peel strength P ₁ and the 10° peel strength P ₂ can be increased by increasing the amount of adhesive material components such as adhesives and pressure sensitive adhesives used in the temporary fixing material (B), and the 10° peel strength P ₁ and the 10° peel strength P ₂ can be decreased by adding a release agent to the temporary fixing material (B).

The mechanical peeling method in this embodiment is not particularly limited, and peeling can be performed using a commercially available device, etc. For example, peeling is preferably performed by the method shown in FIG.
In this method, the wafer (C) side 13 of the laminate (D) is fixed onto a chuck table (not shown) via a dicing tape 14, and then the support (A) 11 is held by a holding mechanism (not shown).
The remover 16 is slid into the interface between the support 11 (A) and the temporary fixing material 12 (B) and an upward force is applied to the end of the support 11 (A), forming a peeling interface between the support 11 (A) and the temporary fixing material 12 (B) that will trigger peeling (Figure 1 (b)).
Pressure is applied by the holding mechanism to warp the support (A) 11, expanding the peeling interface and allowing the peeling to proceed (FIG. 1(c)).
When the peeling interface spreads and a peeling interface is formed over the entire surface between the support body (A) 11 and the temporary fixing material (B) 12, the support body (A) 11 is peeled off from the temporary fixing material (B) 12.
Examples of commercially available devices as described above include XBC Gen2 manufactured by SUSS, EVG805 manufactured by EVG, and TWH-SR series manufactured by Tatsumo Corporation.

At this time, according to the present invention, peeling at the interface between the temporary fixing material 12 (B) and the wafer 13 (C), which is not intended to peel off at this stage, is effectively suppressed, so that the functional layers etc. formed on the wafer 13 (C) are effectively protected by the temporary fixing material 12 (B), minimizing the risk of damage to these functional layers etc. (Figure 2 (a)).

In the prior art, before the peeling between the support 11 (A) and the temporary fixing material 12 (B), peeling may occur at the interface between the temporary fixing material 12 (B) and the wafer 13 (C), which is not intended to be peeled at this stage (FIG. 2(b)). As a result, there was a risk that the electronic circuits formed on the wafer 13 (C) would be damaged during the peeling, or would be damaged in a subsequent process that still requires protection by the temporary fixing material 12 (B).
In the conventional technology, the support (A) could not be completely peeled off because the temporary fixing material (B) (12) remained partially on the support (A) (11) or the temporary fixing material (B) (12) on the wafer (C) (13) was partially damaged (FIG. 2(c)). As a result, uneven stress was applied to the wafer (C) (13) and the support (A) (11), which could cause them to break.
When the temporary bonding material (B) remains on the wafer (C), it may be removed by dissolving it in a solvent.
The present invention solves these problems of the prior art, prevents unintended interface peeling and uneven peeling, or at least significantly reduces the frequency of such occurrences, thereby making it possible to perform multiple and/or diverse processes on the wafer with high productivity and yield without damaging the functional layers formed on the wafer.

The wafer processed by the wafer processing method of the present invention can be subjected to further processes to manufacture a final product. If a functional layer is formed on the wafer, further processes typically used in the manufacture of electronic devices such as semiconductor devices, such as dicing, bonding, packaging, and sealing, can be carried out to manufacture the final product.

The present invention will be described in detail below. Note that the present invention is not limited in any way by the following examples.

The physical properties and characteristics in the examples and comparative examples were evaluated by the following methods.
(1) Mechanical peelability The laminate (D) thus prepared was subjected to a predetermined heat history shown in Table 1, and then fixed at room temperature with the 13 wafer (C) side down on the 14 dicing tape attached to the 15 ring frame, and the 14 dicing tape was vacuum chucked to fix it (FIG. 1(a)). In order to peel the interface between the 11 support (A) and the 12 temporary fixing material (B), as shown in FIG. 1, the 16 remover was slid into the interface between the 11 support (A) and the 12 temporary fixing material (B), and an upward force of typically up to about 120 N was applied to the end of the 11 support (A), forming a peeling interface that triggers peeling between the 11 support (A) and the 12 temporary fixing material (B) (FIG. 1(b)).
Next, pressure was applied to the formed peeled interface to expand the peeled interface, thereby peeling off the support (A) 11 (FIG. 1(c)). The peelability was evaluated according to the following criteria.
◯: The intended support (A)/temporary bonding material (B) interface was peeled off over the entire surface, and no damage occurred to the wafer (C).
x: Unintended peeling occurred at the interface between the temporary bonding material (B) and the wafer (C).

(2) Removability of temporary fixing material (B) from wafer (C) After the mechanical peelability evaluation described above, the 13 wafer (C)/12 temporary fixing material (B) laminate fixed to the 14 dicing tape attached to the 15 ring frame was attached with the 17 adhesive tape on the entire surface of the 12 temporary fixing material (B). The 14 dicing tape was fixed with a vacuum chuck, and the 12 temporary fixing material (B) was peeled off at a peel angle of 90° and a peel speed of 5 mm/s. The peelability was evaluated according to the following criteria.
◯: The temporary bonding material (B) was completely peeled off from the wafer (C), and no damage occurred to the wafer (C).
×: The temporary bonding material (B) could not be peeled off from the wafer (C).

(3) 10° peel strength P ₁ (peel strength between support body/temporary fixing material)
(3-1) In the case where a base film (B ₀ ) is used as a temporary bonding material _, a P ₁ measurement sample was prepared by laminating a pressure-sensitive adhesive layer (B ₁ ) on the side contacting the support (A) 20 to a base film (B 0 ) 19 .
(3-2) In the case where the base film (B ₀ ) is not used as the temporary bonding material, a polyimide film 21 (double-sided plasma treatment, thickness 38 μm, manufactured by Toray DuPont Co., Ltd., product name: Kapton (registered trademark) 150EN-A) was prepared, and a sample for measurement P ₁ was prepared by laminating the same material as the temporary bonding material 12 on top of this.
(3-3) Measurement The _P1 measurement sample prepared in (3-1) or (3-2) above was cut to 2.5 cm x 5 cm, and the surface of the _P1 measurement sample that is the same material as the 20 adhesive layer ( _B1 ) or 12 temporary fixing material was attached to the attachment surface of the 11 support (A) cut to 3 cm x 6 cm by one round trip of a 2 kg roller. Next, the prepared support (A)/ _P1 measurement sample laminate was heated at 140°C for 30 minutes as a condition assuming the pretreatment in step (1) in each example and comparative example. Furthermore, after applying a predetermined heat history shown in Table 1 as a condition assuming step (2), the measurement sample was left at 22.5±1°C and a relative humidity of 50±10% for one week to cool, and then the peel strength _P1 was measured at this temperature and humidity condition using VPA-S (manufactured by Kyowa Interface Science Co., Ltd.) at a tensile speed of 300 mm/min and a peel angle of 10° (Figure 3(a) or (c)).

(4) 10° peel strength _P2 (peel strength between temporary bonding material and wafer)
(4-1) In the case where a base film (B ₀ ) is used as a temporary bonding material, a sample for measuring _P2 was prepared by laminating a pressure-sensitive adhesive layer (B ₂ ) on the side of the base film (B ₀ ) that contacts the wafer (C) (18).
(4-2) In the case where the base film (B ₀ ) is not used as the temporary bonding material, a polyimide film 21 (double-sided plasma treatment, thickness 38 μm, manufactured by Toray DuPont Co., Ltd., product name: Kapton (registered trademark) 150EN-A) was prepared, and a sample for measuring P ₂ was prepared by laminating the same material as the temporary bonding material 12 on top of this.
(4-3) Measurement The _P2 measurement sample prepared in (4-1) or (4-2) above was cut to 2.5 cm x 5 cm, and the surface of the _P2 measurement sample that is the same material as the 18 adhesive layer ( _B2 ) or 12 temporary fixing material was attached to the attachment surface of the wafer (C) cut to 3 cm x 6 cm by one round trip with a 2 kg roller. Next, the prepared wafer (C) / _P2 measurement sample laminate was heated at 140 ° C for 30 minutes as a condition assuming the pretreatment in the step (1) in each example and comparative example. Furthermore, after applying a predetermined heat history shown in Table 1 as a condition assuming the step (2), the measurement sample was left at 22.5 ± 1 ° C and a relative humidity of 50 ± 10% for 1 week to cool, and then the peel strength _P2 was measured at this temperature and humidity condition using VPA-S (manufactured by Kyowa Interface Science Co., Ltd.) at a pulling speed of 300 mm / min and a peel angle of 10 degrees (Figure 3 (b) or (d)).

Details of the materials and ingredients used in the examples and comparative examples are as follows.
Support (A) and wafer (C)
The following glass or Si was used as either the support (A) or the wafer (C):
Glass A support substrate for grinding the back surface of silicon made of borosilicate heat-resistant glass having an outer diameter of 300 or 200 mm and a thickness of 700 μm was used.
・Si
A Si mirror wafer having an outer diameter of 300 or 200 mm and a thickness of 750 μm was used.

Resin/(meth)acrylic resin solution N for forming temporary fixing material (B) :
49 parts by mass of ethyl acrylate, 20 parts by mass of 2-ethylhexyl acrylate, 21 parts by mass of methyl acrylate, 10 parts by mass of glycidyl methacrylate, and 0.5 parts by mass of a benzoyl peroxide-based polymerization initiator as a polymerization initiator were reacted in a solvent consisting of 65 parts by mass of toluene and 50 parts by mass of ethyl acetate at 80° C. for 10 hours. After completion of the reaction, the resulting solution was cooled, and 25 parts by mass of xylene, 5 parts by mass of acrylic acid, and 0.5 parts by mass of tetradecyldimethylbenzylammonium chloride were added to the cooled solution, and the mixture was reacted at 85° C. for 32 hours while blowing in air, to obtain a (meth)acrylic resin solution N.
Silicone modified (meth)acrylic resin solution NS
To 270 parts by mass of the above-mentioned (meth)acrylic resin solution N, 0.3 parts by mass of a carboxy-modified organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: X-22-3710) was added, and the mixture was reacted at 60° C. for 7 days to obtain a silicone-modified (meth)acrylic resin solution NS.
(Meth)acrylic resin solution L
A (meth)acrylic adhesive (Bindceram SA591, manufactured by Mitsui Chemicals, Inc.) was used.
・(Meth)acrylic resin emulsion H
Using 0.5 parts by mass of ammonium persulfate as a polymerization initiator, 63 parts by mass of 2-ethylhexyl acrylate, 21 parts by mass of n-butyl acrylate, 9 parts by mass of methyl methacrylate, 3 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, 1 part by mass of polytetramethylene glycol diacrylate (manufactured by NOF Corporation, trade name: ADT-250), and 2 parts by mass of an aqueous solution of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-1025) were emulsion-polymerized in deionized water at 70° C. After completion of the polymerization, the pH was adjusted to 7.0 using aqueous ammonia to obtain (meth)acrylic resin emulsion H having a solid content of 56.5% by mass.
(Meth)acrylic resin emulsion B
Using 0.5 parts by mass of 4,4'-azobis-4-cyanovaleric acid (manufactured by Otsuka Chemical Co., Ltd., product name: ACVA) as a polymerization initiator, 74 parts by mass of n-butyl acrylate, 14 parts by mass of methyl methacrylate, 9 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, and 3 parts by mass of HS-1025 were emulsion-polymerized in deionized water at 70° C. After completion of the polymerization, the pH was adjusted to 7.0 using aqueous ammonia to obtain a (meth)acrylic resin emulsion B having a solid content of 42.5% by mass.
(Meth)acrylic resin emulsion A
Using 0.65 parts by mass of ACVA as a polymerization initiator, 63 parts by mass of 2-ethylhexyl acrylate, 18 parts by mass of n-butyl acrylate, 12 parts by mass of methyl methacrylate, 3 parts by mass of 2-hydroxyethyl methacrylate, 2 parts by mass of methacrylic acid, 1 part by mass of acrylamide, 1 part by mass of ADT-250, and 2 parts by mass of Aqualon HS-1025 were emulsion-polymerized in deionized water at 70° C. After completion of the polymerization, the pH was adjusted to 7.0 using aqueous ammonia to obtain a (meth)acrylic resin emulsion A having a solid content of 42.5% by mass.
(Meth)acrylic resin emulsion S
Using 0.5 part by mass of ACVA as a polymerization initiator, 47 parts by mass of n-butyl acrylate, 22 parts by mass of methyl methacrylate, 9 parts by mass of 2-hydroxyethyl methacrylate, 15 parts by mass of methacrylic acid, 8 parts by mass of acrylamide, and 0.2 part by mass of AQUALON HS-1025 were emulsion-polymerized in deionized water at 70° C. to obtain a (meth)acrylic resin emulsion S with a solids content of 40% by mass.

Base film B ₀
PEN Film A polyethylene naphthalate film (corona-treated on both sides, thickness: 50 μm, manufactured by Toyobo Film Solutions Co., Ltd., Teonex Q83) was used.
PET Film: A biaxially oriented polyethylene terephthalate film (corona-treated on both sides, thickness 38 μm, manufactured by Toray Industries, Inc., Lumirror S10) was used.

Example 1
As the adhesive layer (B ₁ ) on the support (A) side, 2.84 parts by mass of HDI isocyanurate (manufactured by Tosoh Corporation, trade name: Coronate HX), 50 parts by mass of dipentaerythritol penta/hexaacrylate (manufactured by Toagosei Co., Ltd., trade name: Aronix M-402), 2.0 parts by mass of silicone diacrylate (manufactured by Daicel Allnex Co., Ltd., trade name: Ebecryl 350), and 2 parts by mass of Perkadox 12XL25 manufactured by Kayaku Nouryon Co., Ltd. were added to 250 parts by mass of the (meth)acrylic resin solution L to obtain a coating liquid for the adhesive layer (B ₁ ) on the support (A) side. This coating liquid was applied to the substrate B ₀ (PEN film) and dried at 100 ° C. for 10 minutes to form an adhesive resin layer having a thickness of 25 μm. Next, a silicone release-treated polyethylene terephthalate film (separator) was laminated to obtain a laminate of the adhesive layer (B ₁ )/substrate (B ₀ ) on the support (A) side with the separator.
As the adhesive layer (B ₂ ) on the wafer (C) side, a pressure-sensitive adhesive coating liquid was prepared by mixing 42.6 parts by mass of (meth)acrylic resin emulsion H, 57.4 parts by mass of (meth)acrylic resin emulsion B, 0.4 parts by mass of dimethylethanolamine, 3.4 parts by mass of an epoxy compound (product name: Ex-1610, manufactured by Nagase ChemteX Corporation), 13 parts by weight of butyl carbinol, and 20 parts by weight of pure water. This coating liquid was applied to a silicone release-treated polyethylene terephthalate film (separator) and dried at 120°C for 3 minutes to form a pressure-sensitive adhesive resin layer having a thickness of 13 μm. Next, the above-mentioned adhesive layer (B ₁ )/substrate (B ₀ ) laminate was laminated to the substrate (B ₀ ) side to prepare a precursor of the temporary fixing material (B) with a separator, which has a three-layer structure of adhesive layer (B ₁ )/substrate (B ₀ )/adhesive layer (B ₂ ). The separators used on both sides of the three-layer structure were peeled off, and the support (A) and wafer (C) shown in Table 1 were laminated using a vacuum laminator and heated at 140° C. for 30 minutes to prepare a laminate (D) consisting of the support (A)/temporary fixing material (B)/wafer (C) in this order. The results of evaluating the mechanical peelability and removability of the laminate (D) are shown in Table 1.
Separately, a laminate of the adhesive layer (B ₁ )/substrate (B ₀ ) and a laminate of the adhesive layer (B ₂ )/substrate (B ₀ ) were separately prepared (the coating conditions were the same), and the 10° peel strengths P ₁ and P ₂ were measured by the above-mentioned method. The measurement results are shown in Table 1.

Example 2
As the adhesive layer (B ₁ ) on the support (A) side, 0.5 parts by mass of HDI isocyanurate (manufactured by Tosoh Corporation, trade name: Coronate HX), 12 parts by mass of dipentaerythritol penta/hexaacrylate (manufactured by Toagosei Co., Ltd., trade name: Aronix M-400), 1.5 parts by mass of silicone diacrylate (manufactured by Daicel-Allnex Co., Ltd., trade name: Ebecryl 350), and 2 parts by mass of Perkadox 12XL25 manufactured by Kayaku Nouryon Co., Ltd. were added to 270 parts by mass of (meth)acrylic resin solution N to obtain a coating liquid for the adhesive layer (B ₁ ) on the support (A) side. This coating liquid was applied to a polyethylene terephthalate film (separator) subjected to a silicone release treatment and dried at 100 ° C. for 10 minutes to form an adhesive resin layer having a thickness of 100 μm. Next, a substrate B ₀ (PET film) was attached to obtain a laminate of the adhesive layer (B ₁ )/substrate (B ₀ ) on the support (A) side with a separator.
Next, the coating liquid for the adhesive layer (B ₂ ) on the wafer (C) side in Example 1 was applied to a silicone release-treated polyethylene terephthalate film (separator) and dried at 120°C for 3 minutes to form an adhesive resin layer with a thickness of 6 μm. This was then bonded to the substrate (B _{0 ) side of the above-mentioned adhesive layer (B 1 )} /substrate (B ₀ ) laminate to produce a pre-heat treatment temporary fixing material (B) precursor having a three-layer structure of adhesive layer (B ₁ )/substrate (B ₀ )/adhesive layer (B ₂ ) with separator.
The separators used on both sides of the three-layer structure were peeled off, and the support (A) and wafer (C) shown in Table 1 were laminated using a vacuum laminator and heated at 140° C. for 30 minutes to produce a laminate (D) consisting of the support (A)/temporary bonding material (B)/wafer (C) in that order. The mechanical peelability and removability of the laminate (D) were evaluated, and the results are shown in Table 1.
Separately, a laminate of the adhesive layer (B ₁ )/substrate (B ₀ ) and a laminate of the adhesive layer (B ₂ )/substrate (B ₀ ) were separately prepared (the coating conditions were the same), and the 10° peel strengths P ₁ and P ₂ were measured by the above-mentioned method. The measurement results are shown in Table 1.

Example 3
To 269 parts by mass of silicone-modified (meth)acrylic resin solution NS, 1.0 parts by mass of HDI isocyanurate (manufactured by Tosoh Corporation, product name: Coronate HX) and 2 parts by mass of Percadox 12XL25 manufactured by Kayaku Nouryon Co., Ltd. were added to obtain an adhesive coating liquid for temporary fixing material (B). This coating liquid was applied to a silicone-release-treated polyethylene terephthalate film (separator), and then dried at 100 ° C for 10 minutes to form an adhesive resin layer with a thickness of 100 μm. Next, a silicone-release-treated polyethylene terephthalate film (separator) was attached to prepare a precursor of temporary fixing material (B) before heat treatment (with separators on both sides). The separators on both sides were peeled off, and the support plate (A) and wafer (C) described in Table 1 were laminated with a vacuum laminator, and heated at 140 ° C for 30 minutes to prepare a laminate (D) consisting of the support (A) / temporary fixing material (B) / wafer (C) in that order. The mechanical peelability and removability of the laminate (D) were evaluated, and the results are shown in Table 1.
The 10° peel strengths _P1 and _P2 were measured according to the above-mentioned method (when the base film (B ₀ ) was not used as the temporary fixing material). The measurement results are shown in Table 1.

Example 4
The coating liquid for the adhesive layer (B ₁ ) on the support (A) side in Example 1 was applied to a silicone release-treated polyethylene terephthalate film (separator) and dried for 10 minutes at 100° C. to form an adhesive resin layer having a thickness of 31 μm. Next, a substrate B ₀ (PET film) was bonded to the coating liquid, thereby obtaining a laminate of the adhesive layer (B ₁ ) on the support (A) side/substrate (B ₀ ) with a separator.
Next, as the adhesive layer (B ₂ ) on the wafer (C) side, 100 parts by mass of (meth)acrylic resin emulsion A, 0.7 parts by mass of (meth)acrylic resin emulsion S, 0.3 parts by mass of dimethylethanolamine, 5 parts by mass of an epoxy compound (manufactured by Nagase ChemteX Corporation, product name: Ex-614), 9 parts by weight of butyl carbinol, and 12 parts by weight of pure water were mixed to prepare an adhesive coating liquid. This coating liquid was applied to a silicone release-treated polyethylene terephthalate film (separator) and dried at 120°C for 3 minutes to form an adhesive resin layer with a thickness of 20 μm. Next, the adhesive layer (B ₁ )/substrate (B ₀ ) laminate was laminated on the substrate (B ₀ ) side to prepare a pre-heat-treated temporary fixing material (B) precursor having a three-layer structure of adhesive layer (B ₁ )/substrate (B ₀ )/adhesive layer (B ₂ ) with a separator. The separators used on both sides of the three-layer structure were peeled off, and the support (A) and wafer (C) shown in Table 1 were laminated using a vacuum laminator and heated at 140° C. for 30 minutes to produce a laminate (D) consisting of the support (A)/temporary bonding material (B)/wafer (C) in that order. The mechanical peelability and removability of the laminate (D) were evaluated, and the results are shown in Table 1.
Separately, a laminate of the adhesive layer (B ₁ )/substrate (B ₀ ) and a laminate of the adhesive layer (B ₂ )/substrate (B ₀ ) were separately prepared (the coating conditions were the same), and the 10° peel strengths P ₁ and P ₂ were measured by the above-mentioned method. The measurement results are shown in Table 1.

(Comparative Example 1)
To 69 parts by mass of silicone-modified (meth)acrylic resin solution N2, 0.1 parts by mass of HDI isocyanurate (manufactured by Tosoh Corporation, trade name: Coronate HX), 6 parts by weight of pentaerythritol tri/tetraacrylate (manufactured by Toagosei Co., Ltd., trade name: M-450), and 2 parts by mass of Percadox 12XL25 (manufactured by Kayaku Nouryon Co., Ltd.) were added to obtain an adhesive coating liquid for temporary fixing material (B). This coating liquid was applied to a silicone-release-treated polyethylene terephthalate film (separator), and then dried at 100 ° C. for 10 minutes to form an adhesive resin layer with a thickness of 50 μm. Next, a silicone-release-treated polyethylene terephthalate film (separator) was attached to prepare a precursor of temporary fixing material (B) before heat treatment (with double-sided separator). The separators on both sides were peeled off, and the support plate (A) and wafer (C) shown in Table 1 were laminated using a vacuum laminator and heated at 140° C. for 30 minutes to produce a laminate (D) consisting of the support (A)/temporary bonding material (B)/wafer (C) in that order. The mechanical peelability and removability of the laminate (D) were evaluated, and the results are shown in Table 1.
The 10° peel strengths _P1 and _P2 were measured according to the above-mentioned method (when the base film (B ₀ ) was not used as the temporary fixing material). The measurement results are shown in Table 1.

The wafer processing method of the present invention enables multiple and/or diverse processes to be performed on wafers with high productivity and yield without damaging electronic components such as functional layers formed on the wafer, and therefore contributes greatly to improving the productivity of electronic devices and has high applicability in various industrial fields, including the electronic components industry, including the semiconductor process industry, the electrical and electronics industry that uses electronic components, the transportation machinery industry, the information and communications industry, and the precision machinery industry.

11: Support (A)
12: Temporary fixing material (B)
13: Wafer (C)
14: Dicing tape 15: Ring frame 16: Remover 17: Adhesive tape 18: Adhesive layer ( _B2 ) on wafer (C) side
19: Base film (B ₀ )
20: Adhesive layer (B ₁ ) on support (A) side
21: Polyimide film

Claims (13)

A step (1) of stacking a support (A), a temporary fixing material (B), and a wafer (C) located on the side of the temporary fixing material (B) opposite to the support (A);
A step (2) of subjecting the wafer (C) to at least one treatment selected from a heat treatment, a mechanical processing treatment, a wet processing treatment, and a laser processing treatment; and a step (3) of separating the wafer (C) from a laminate (D) having the wafer (C) after the treatment.
A method for processing a wafer, comprising:
the ratio P2/P1 of the 10° peel strength _P1 between the support (A)/temporary fixing material (B) and the 10° peel strength P2 between the temporary fixing material (B)/ _wafer (C), measured while _maintaining the angle between the peeled layers at 10°, is 1.1 or _more ;
The method for treating a wafer as described above, wherein the temporary bonding material (B) contains a release agent . The method for treating a wafer according to claim 1 , wherein the peel strength P ₁ is 10 N/25 mm or less. The method for treating a wafer according to claim 1 or 2, wherein the adhesive layer of the temporary fixing material (B) in contact with the support (A) and the adhesive layer in contact with the wafer (C) have different compositions. The method for treating a wafer according to any one of claims 1 to 3, wherein the separation of the wafer (C) from the laminate (D) is achieved by separating the support (A) from the temporary bonding material (B) and then removing the temporary bonding material (B) remaining on the wafer (C). The wafer processing method according to claim 4, wherein the method for separating the temporary bonding material (B) and the support (A) is mechanical peeling. The method for treating a wafer according to any one of claims 1 to 5, wherein the temporary fixing material (B) contains a curable adhesive component. 7. The method for treating a wafer according to claim 1, wherein the temporary bonding material (B) is a base film (B ₀ ) having a pressure-sensitive adhesive material laminated on both sides thereof. The method for treating a wafer according to claim 1 , further comprising forming an electrode on the wafer (C). 9. The method for treating a wafer according to claim 1 , wherein in the step (2), a surface of the wafer (C) on which no electrode is formed is ground. 10. The method for treating a wafer according to claim 9 , wherein the thickness of the wafer (C) after grinding is 1 μm or more and 200 μm or less. A method for manufacturing an electronic device, comprising carrying out the wafer processing method according to any one of claims 1 to 10 . The method for producing an electronic device according to claim 11 , wherein the electronic device has a structure in which semiconductor chips are stacked. A laminate (D) in which a support (A), a temporary fixing material (B), and a wafer (C) located on a side of the temporary fixing material (B) opposite to the support (A),
the ratio P2/P1 of the 10° peel strength _P1 between the support (A)/temporary fixing material (B) and the 10° peel strength P2 between the temporary fixing material (B)/ _wafer (C), measured while _maintaining the angle between the peeled layers at 10°, is 1.1 or _more ;
A laminate, wherein the temporary fixing material (B) contains a release agent .

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