Method for temporarily fixing base material layer, laminate, and method for recovering base material layer

Abstract

According to the present invention, a method for temporarily fixing a base material layer to a support that has had a cured resin layer (A) formed directly on the surface thereof includes a layering step for providing the base material layer on the cured resin layer (A) that has been formed on the support such that a composition that contains a prescribed monomer (b) is sandwiched therebetween and a curing step for curing the composition that contains the monomer (b) and thereby forming a cured resin layer (B) and temporarily fixing the base material layer to the support.

Description

Method for temporarily fixing a substrate layer, laminate, and method for recovering a substrate layer

[0001] The present invention relates to a method for temporarily fixing a substrate layer, a laminate, and a method for recovering a substrate layer.

[0002] In recent years, semiconductor wafers, such as compound semiconductors, are increasingly being equipped with devices on both the front and back sides. This trend is attributed to 3D stacking technology, which electrically connects the front and back sides, and the existence of vertically structured semiconductors such as SiC power semiconductors. Furthermore, in optical semiconductors, there are configurations where light is incident from the back side and received on the front side.

[0003] Given the background described above, it is preferable that the wafers being handled be thin in order to reduce the distance between the front and back surfaces. In this regard, compound semiconductor wafers in particular are very brittle, making thinning difficult, which presents a challenge.

[0004] Furthermore, since photolithography processes are sometimes applied to the back surface of wafers, resistance to high temperatures (plasma CVD, diffusion process) and chemical solutions (resist stripping solution, developer, wet etching) is also required.

[0005] From the above perspective, when performing processing such as machining or attaching devices to the back surface of a wafer, it is necessary to use a support substrate (support) and temporarily fix the wafer by stacking it on the support substrate (support). Furthermore, it is required that the wafer can be peeled off the support substrate after processing.

[0006] To address such requirements, for example, Patent Document 1 discloses the use of a composition containing two predetermined types of bifunctional (meth)acrylates and a photoradical polymerization initiator as a temporary fixative to temporarily fix a semiconductor wafer substrate to a support member. Patent Document 1 states that such a composition is excellent in terms of curing speed, compatibility with spin coating processes, etc., and is suitable for UV laser peeling processes.

[0007] Furthermore, for example, Patent Document 2 discloses the use of a temporary adhesive layer consisting of a predetermined three-layer system for bonding a wafer and a support. Patent Document 2 states that such a temporary adhesive layer can be easily peeled off.

[0008] Japanese Patent Publication No. 2024-009973 Japanese Patent Publication No. 2013-048215

[0009] In the technology disclosed in Patent Document 1, a temporary fixative containing predetermined components results in relatively strong adhesion between the semiconductor wafer substrate and the support member. Therefore, when peeling off the semiconductor wafer substrate, irradiation with a UV laser is practically essential, which presents a problem of high processing load. Furthermore, due to such strong adhesion, there is a concern that the semiconductor wafer substrate may be damaged during peeling.

[0010] Furthermore, the technology disclosed in Patent Document 2 has the problem of high processing load because it uses a temporary adhesive layer consisting of three layers. In addition, with such a multilayer temporary adhesive layer, the circuit surface of the wafer may be damaged when peeling the wafer from the support.

[0011] In view of the above, it is required that the wafer be not only fixed to the support, but also that the wafer be prevented from being damaged when it is subsequently peeled off the support, and that the peeling process be carried out easily.

[0012] Furthermore, residues originating from the temporary fixative may adhere to the wafer after it has been detached from the support. Therefore, it is also required that such residues be easily removed.

[0013] Therefore, the present invention aims to provide a method for temporarily fixing a substrate layer, such as a wafer, to a support, which allows for easy removal of the substrate layer without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. The present invention also aims to provide a laminate in which a substrate layer, such as a wafer, is temporarily fixed to a support, which allows for easy removal of the substrate layer from the support without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. Furthermore, the present invention aims to provide a method for recovering a substrate layer using the above-described laminate, which allows for easy recovery of the substrate layer from which residue has been removed, without damaging it.

[0014] The means to solve the aforementioned problem are as follows:

[0015] <1> A method for temporarily fixing a base layer to a support, wherein the support has a cured resin layer (A) directly formed on its surface, and the method comprises a lamination step of arranging the base layer on the cured resin layer (A) formed on the support such that a composition containing monomer (b) is sandwiched between them, and a curing step of curing the composition containing monomer (b) so that a cured resin layer (B) is formed and the base layer is temporarily fixed to the support, wherein the monomer (b) is a monomer whose polymerized polymer has a water absorption rate of 5% or more when immersed in water at 25°C for 120 minutes.

[0016] <2> The temporary fixing method according to <1>, wherein the cured resin layer (A) has a fine uneven structure on the surface opposite to the surface that contacts the support.

[0017] <3> The temporary fixing method according to <2>, wherein the cured resin layer (A) has an inorganic film on the surface of the fine uneven structure.

[0018] <4> A laminate comprising: a support; a cured resin layer (A) directly formed on the surface of the support; a cured resin layer (B) on the cured resin layer (A); and a base layer on the cured resin layer (B), wherein the cured resin layer (B) contains a polymer (b) having a water absorption rate of 5% or more when immersed in water at 25°C for 120 minutes.

[0019] <5> The laminate according to <4>, wherein the cured resin layer (A) has a fine uneven structure on the surface opposite to the surface in contact with the support.

[0020] <6> The laminate according to <5>, wherein the cured resin layer (A) has an inorganic film on the surface of the fine uneven structure.

[0021] <7> A method for recovering a substrate layer from a support on which the substrate layer is temporarily fixed, comprising: a peeling step of peeling and removing the substrate layer from a laminate according to any one of <4> to <6>; and a solvent contact step of contacting the peeled substrate layer with a solvent to remove any residue of the cured resin layer (B) adhering to the substrate layer.

[0022] According to the present invention, it is possible to provide a method for temporarily fixing a substrate layer, such as a wafer, to a support, which allows for easy removal of the substrate layer without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. Furthermore, according to the present invention, it is possible to provide a laminate in which a substrate layer, such as a wafer, is temporarily fixed to a support, which allows for easy removal of the substrate layer from the support without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. Furthermore, according to the present invention, it is possible to provide a method for recovering a substrate layer using the above-described laminate, which allows for easy recovery of the substrate layer from which residue has been removed, without damaging it.

[0023] This is a schematic diagram showing part of an example process for forming a cured resin layer (A) on the surface of a support. This is a schematic diagram showing part of an example process for forming a cured resin layer (A) on the surface of a support. This is a schematic diagram showing one embodiment of a support in which a cured resin layer (A) is directly formed on the surface, which can be used in the present invention. This is a schematic diagram showing the lamination process in a method for temporarily fixing a substrate layer according to one embodiment of the present invention. This is a schematic diagram showing the curing process in a method for temporarily fixing a substrate layer according to one embodiment of the present invention. This is a schematic diagram showing a laminate according to one embodiment of the present invention. This is a schematic diagram showing the peeling process in a method for recovering a substrate layer according to one embodiment of the present invention. This is a schematic diagram showing part of the solvent contact

[0024] The present invention will now be described in detail based on embodiments.

[0025] (Method for temporarily fixing a substrate layer) A method for temporarily fixing a substrate layer according to one embodiment of the present invention (hereinafter sometimes referred to as "the temporary fixing method of this embodiment") is a method for temporarily fixing a substrate layer to a support. In the temporary fixing method of this embodiment, a cured resin layer (A) is directly formed on the surface of the support. The temporary fixing method of this embodiment includes at least a lamination step of arranging the substrate layer on the cured resin layer (A) formed on the support so as to sandwich a composition containing monomer (b), and a curing step of curing the composition containing monomer (b), thereby forming a cured resin layer (B) and temporarily fixing the substrate layer to the support. Here, monomer (a) is a monomer whose water absorption rate is 5% or more when the polymer obtained by polymerization is immersed in water at 25°C for 120 minutes. According to the temporary fixing method of this embodiment, when peeling off a substrate layer such as a wafer after it has been temporarily fixed to a support, the substrate layer can be easily peeled off without damaging it, and any residue that may adhere to the substrate layer can be easily removed.

[0026] <Substrate Layer> One typical example of a substrate layer is a wafer (semiconductor wafer) such as a silicon wafer. Bumps, wiring, insulating films, etc., may be formed on such a wafer. In this embodiment, the substrate layer is not limited to a wafer, and various layered (sheet-like) members such as glass substrates, resin substrates, metal substrates, metal foils, polishing pads, resin coatings, and various devices can be used. In particular, layered (sheet-like) members that require processing such as processing or attachment of devices to the back surface can be suitably used.

[0027] <Support> The support is not particularly limited and includes, for example, a glass substrate; a silicon wafer, a quartz wafer, and the like. The support has a flat surface and is typically a layered (sheet-like) member. The support may be the same as or different from the base layer. The surface of the support on which the cured resin layer (A) is directly formed may be subjected to a surface treatment such as silane treatment.

[0028] <Cured Resin Layer (A)> In the temporary fixing method of this embodiment, the support has a cured resin layer (A) directly formed on its surface. In other words, the temporary fixing method of this embodiment uses a support that has a cured resin layer (A) directly formed on its surface in advance.

[0029] The cured resin layer (A) can be formed, for example, by applying a composition containing a photopolymerization initiator and a polymerizable compound (uncured composition) onto a support and curing it by light irradiation.

[0030] Examples of photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropane-1-one.

[0031] Examples of polymerizable compounds include acrylic polymerizable compounds and epoxy polymerizable compounds.

[0032] Acrylic polymerizable compounds are monomers, oligomers, or prepolymers having one or more acrylic groups in their molecule. Here, the monomers are further classified into monofunctional monomers having one acrylic group in their molecule, difunctional monomers having two acrylic groups in their molecule, and polyfunctional monomers having three or more acrylic groups in their molecule.

[0033] Examples of the above monofunctional monomers include carboxylic acids (acrylic acid), hydroxy compounds (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate), alkyl or alicyclic monomers (isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isovonyl acrylate, cyclohexyl acrylate), and other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, N,N-dimethylaminoethyl acrylate). Examples include N,N-dimethylaminopropylacrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N,N-diethylacrylamide, N-vinylpyrrolidone, 2-(perfluorooctyl)ethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluoro-3-methylbutyl)ethyl acrylate), 2,4,6-tribromophenol acrylate, 2,4,6-tribromophenol methacrylate, 2-(2,4,6-tribromophenoxy)ethyl acrylate), and 2-ethylhexyl acrylate.

[0034] Examples of the above-mentioned difunctional monomers include tri(propylene glycol) diacrylate, trimethylolpropane-diallyl ether, and urethane acrylate.

[0035] Examples of the polyfunctional monomers mentioned above include trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETA), dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and ditrimethylolpropane tetraacrylate.

[0036] Epoxy polymerizable compounds are monomers, oligomers, or prepolymers having one or more epoxy groups in their molecule.

[0037] Examples of epoxy polymerizable compounds include various bisphenol-type epoxy resins (bisphenol A type, bisphenol F type, etc.), novolac-type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene-type epoxy resins, biphenyl-type epoxy resins, phenol novolac-type epoxy resins, stilbene-type epoxy resins, triphenolmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, and prepolymers thereof.

[0038] Preferably, the cured resin layer (A) has a fine uneven surface on the surface opposite to the surface in contact with the support. In this case, an anchoring effect occurs between the cured resin layer (A) and the cured resin layer (B) formed in the curing process described later, and the substrate layer is more firmly temporarily fixed to the support. As a result, even if the substrate layer is exposed to a high-temperature environment (such as plasma CVD) or a chemical solution (such as a resist stripping solution) while temporarily fixed, the mechanical temporary fixation can be well maintained. In this specification, "fine uneven surface" refers to a structure in which the unevenness is arranged with an average period of less than or equal to the wavelength of visible light (for example, less than or equal to 830 nm).

[0039] The method for forming the cured resin layer (A) having the fine concavo-convex structure on the support is not particularly limited, and an example of the process can be described using FIGS. 1A and 1B. First, the uncured composition 20a is applied onto the flat surface of the support 10. Next, using a mold 50 having a fine concavo-convex structure on its surface, the mold 50 is pressed against the support 10 such that the fine concavo-convex structure of the mold 50 contacts the uncured composition 20a on the support 10 (FIG. 1A). Such pressing of the mold 50 against the support 10 may be performed by sandwiching the uncured composition 20a between the support 10 and the mold 50. Next, while maintaining the pressing, light such as ultraviolet light is irradiated to cure the uncured composition 20a (FIG. 1B). Thereby, the cured resin layer (A) 20 with the fine concavo-convex structure 21 transferred onto its surface can be formed. Here, the fine concavo-convex structure 21 of the cured resin layer (A) 20 is an inverted structure of the fine concavo-convex structure of the mold 50. Therefore, the adjustment of specifications such as the pitch, size, and shape of the fine concavo-convex structure 21 of the cured resin layer (A) 20 can be performed by appropriately changing the fine concavo-convex structure formed on the mold 50.

[0040] When the cured resin layer (A) 20 includes the fine concavo-convex structure 21, as shown in FIG. 2, the cured resin layer (A) 20 preferably includes an inorganic film 22 on the surface of the fine concavo-convex structure 21. In this case, while generating an anchor effect when temporarily fixing the base material layer, the peelability when the base material layer is peeled off and recovered later can be enhanced.

[0041] Examples of the material constituting the inorganic film 22 include ITO (indium tin oxide), SiO ２ , Si, SiN ｘ and TiO ２ etc. Such an inorganic film 22 can be formed on the surface of the cured resin layer (A) 20 by sputtering or the like.

[0042] Next, each step in the temporary fixing method of the present embodiment will be described while referring to FIGS. 3A and 3B.

[0043] <Lamination Process> In the temporary fixing method of this embodiment, in the lamination process, the base material layer 1 is arranged on the cured resin layer (A) 20 formed on the support 10 so as to sandwich the composition (uncured composition 30a) containing the monomer (b). The composition (uncured composition 30a) containing the monomer (b) will be described later.

[0044] The arrangement of the base material layer 1 on the cured resin layer (A) 20 may be performed as follows: as shown in Fig. 3A, the uncured composition 30a is applied on the cured resin layer (A) 20 formed on the support 10, and then the base material layer 1 is laminated on the applied uncured composition 30a.

[0045] In this lamination process, typically, the cured resin layer (A) 20 and the uncured composition 30a are in direct contact. Also, in this lamination process, typically, the base material layer 1 and the uncured composition 30a are in direct contact.

[0046] Further, when the cured resin layer (A) 20 has the fine concavo-convex structure 21, typically, the fine concavo-convex structure 21 and the uncured composition 30a are in direct contact. Furthermore, when the cured resin layer (A) 20 has the inorganic film 22 on the surface of the fine concavo-convex structure 21, typically, the inorganic film 22 and the uncured composition 30a are in direct contact.

[0047] In the lamination process, the thickness (coating thickness) of the uncured composition 30a is not particularly limited.

[0048] <Curing Process> Next, in the temporary fixing method of this embodiment, in the curing process, the uncured composition 30a sandwiched between the cured resin layer (A) 20 and the base material layer 1 is cured (see Fig. 3B). In this curing process, monomers such as the monomer (b) contained in the uncured composition 30a are polymerized, and due to the curing of the uncured composition 30a, the cured resin layer (B) 30 is formed. As a result, the base material layer 1 is temporarily fixed to the support 10. Also, as a result, a laminate in which the support 10, the cured resin layer (A) 20, the cured resin layer (B) 30, and the base material layer 1 are laminated in this order is obtained.

[0049] The curing method can be appropriately selected based on the components (monomers) contained in the uncured composition 30a, but examples include light irradiation (photocuring) and heating (thermocuring).

[0050] <Composition containing monomer (b)> As described above, the uncured composition 30a sandwiched between the substrate layer 1 and the cured resin layer (A) 20 in the lamination process must contain monomer (b). In this specification, "monomer (b)" is defined as a monomer whose water absorption rate (hereinafter sometimes referred to as "polymer water absorption rate") when the polymer obtained by polymerizing it is immersed in water at 25°C for 120 minutes is 5% or more. In short, monomer (b) is a monomer compound that exhibits water absorption (liquid absorption) when it is made into a polymer. Also, "polymer obtained by polymerizing monomer (b)" corresponds to "polymer (b)" in this specification. Monomer (b) may be used alone or in combination of two or more types.

[0051] The substrate layer 1 can be temporarily fixed to the support 10 by using the uncured composition 30a containing monomer (b) in the manner described above to form a cured resin layer (B). Furthermore, after processing the back surface of the substrate layer 1 or attaching a device while it is temporarily fixed, it is necessary to peel the substrate layer 1 from the support 10, but in this case, the substrate layer 1 can be easily peeled off without damaging it. Moreover, when peeling, residue of the cured resin layer (B) 30 may adhere to the substrate layer 1, but this residue of the cured resin layer (B) 30 can exhibit water absorption (liquid absorption) and swelling effects due to monomer (b) upon contact with a solvent (contact with a solvent will be described later). Therefore, any residue that may adhere to the substrate layer 1 can be easily removed.

[0052] The monomer (b) is not particularly limited as long as it has a polymer water absorption rate of 5% or more as described above. Specifically, as monomer (b), for example, the following formula (1): [In equation (1), R is -CH ２ -O- or -CH ２ -CH ２Examples of compounds represented by [-O-, where the sum of l, m, and n is 5 to 30] include those represented by [-O-]. From the viewpoint of exhibiting a higher polymer water absorption rate, R in formula (1) is more preferably -CH ２ -CH ２ It is -O-. Furthermore, from the viewpoint of exhibiting a higher polymer water absorption rate, the sum of l, m, and n is more preferably 9 to 25, and even more preferably 15 to 22.

[0053] In addition to those mentioned above, specific examples of monomer (b) include dimethylacrylamide, for example.

[0054] The polymer water absorption rate of monomer (b) used in this embodiment must be 5% or more, but from the viewpoint of more reliably obtaining the effects of the present invention, 15% or more is preferable, and 20% or more is even preferable.

[0055] The uncured composition 30a containing monomer (b) may further contain monomers other than monomer (b). Examples of monomers other than monomer (b) include acrylic polymerizable compounds other than monomer (b) and epoxy polymerizable compounds other than monomer (b). The acrylic polymerizable compounds and epoxy polymerizable compounds are as described above for the cured resin layer (A).

[0056] In the uncured composition 30a, the proportion of monomer (b) to the total monomer is preferably 50% by mass or more, more preferably 60% by mass, and even more preferably 70% by mass or more, from the viewpoint of more reliably obtaining the effects of the present invention. Alternatively, the proportion of monomer (b) to the total monomer can be 100% by mass (i.e., the monomer in the uncured composition 30a consists only of monomer (b)).

[0057] The uncured composition 30a containing monomer (b) may further contain a photopolymerization initiator. Examples of photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropane-1-one.

[0058] The uncured composition 30a containing monomer (b) may also contain appropriate amounts of various additives such as inorganic fillers, organic fillers, leveling agents, surface modifiers, and defoaming agents.

[0059] (Laminate) A laminate according to one embodiment of the present invention (hereinafter sometimes referred to as "the laminate of this embodiment") comprises a support 10, a cured resin layer (A) 20 directly formed on the surface of the support 10, a cured resin layer (B) 30 on the cured resin layer (A) 20, and a base material layer 1 on the cured resin layer (B) 30, wherein the cured resin layer (B) 30 contains a polymer (b) whose water absorption rate is 5% or more when immersed in water at 25°C for 120 minutes.

[0060] Because the laminate of this embodiment has the layer configuration described above, the base layer 1 is temporarily fixed to the support 10, and when peeling the base layer 1 from the support 10, it can be easily peeled off without damaging the base layer 1. Furthermore, when peeling, residue of the cured resin layer (B) 30 may adhere to the base layer 1, but this residue of the cured resin layer (B) 30 can exhibit water absorption (liquid absorption) and swelling effects due to the polymer (b) upon contact with a solvent (contact with the solvent will be described later). Therefore, any residue that may adhere to the base layer 1 can be easily removed. Accordingly, with the laminate of this embodiment, the base layer 1 such as a wafer is temporarily fixed to the support 10, and when peeling the base layer 1 from the support 10, it can be easily peeled off without damaging the base layer 1, and any residue that may adhere to the base layer 1 can be easily removed.

[0061] Furthermore, since the laminate of this embodiment has hardened layers other than the base layer 1 and the support 10, it can withstand high-temperature environments such as 300°C.

[0062] The laminate of this embodiment is, for example, a laminate obtained by the temporary fixing method of this embodiment described above. Furthermore, the base layer 1 and the support 10 are the same as those previously described in the temporary fixing method of this embodiment. Also, the formation of the cured resin layer (A) 20 is the same as those previously described in the temporary fixing method of this embodiment.

[0063] As shown in Figure 4, in the laminate 100 of this embodiment, it is preferable that the cured resin layer (A) 20 has a fine uneven structure 21 on the surface opposite to the surface that contacts the support 10. In this case, an anchoring effect occurs between the cured resin layer (A) 20 and the cured resin layer (B) 30, and the base layer 1 is more firmly temporarily fixed to the support 10. As a result, even if the base layer 1 is exposed to a high-temperature environment (such as plasma CVD) or a chemical solution (such as a resist stripping solution) while temporarily fixed, the mechanical temporary fixation can be well maintained. The fine uneven structure 21 in the laminate 100 is the same as that described above for the temporary fixation method of this embodiment.

[0064] Furthermore, if the cured resin layer (A) 20 has a fine uneven structure 21, it is preferable that the cured resin layer (A) 20 has an inorganic film 22 on the surface of the fine uneven structure 21, as shown in Figure 4. In this case, an anchoring effect can be generated when the base material layer 1 is temporarily fixed, and the peelability can be improved when the base material layer 1 is peeled off and recovered afterward. The inorganic film 22 in the laminate 100 is the same as that described above for the temporary fixing method of this embodiment.

[0065] In the laminate 100 of this embodiment, typically the support 10 and the cured resin layer (A) 20 are in direct contact. Also, in the laminate 100 of this embodiment, typically the cured resin layer (A) 20 and the cured resin layer (B) 30 are in direct contact. Also, in the laminate 100 of this embodiment, typically the base material layer 1 and the cured resin layer (B) 30 are in direct contact.

[0066] Furthermore, if the cured resin layer (A) 20 has a fine uneven structure 21, typically the fine uneven structure 21 and the cured resin layer (B) 30 are in direct contact. Moreover, if the cured resin layer (A) 20 has an inorganic film 22 on the surface of the fine uneven structure 21, typically the inorganic film 22 and the cured resin layer (B) 30 are in direct contact.

[0067] <Cured resin layer (B) containing polymer (b)> As described above, the cured resin layer (B) 30 in the laminate 100 of this embodiment must contain polymer (b). In this specification, "polymer (b)" is defined as a polymer whose water absorption rate is 5% or more when immersed in water at 25°C for 120 minutes. In short, polymer (b) is a compound that exhibits water absorption (liquid absorption). Polymer (b) may be used alone or in combination of two or more types.

[0068] Polymer (b) can be obtained, for example, by polymerizing monomer (b) as described above.

[0069] The water absorption rate of the polymer (b) described above must be 5% or more, but from the viewpoint of more reliably obtaining the effects of the present invention, it is preferably 15% or more, and more preferably 20% or more.

[0070] The cured resin layer (B) 30 containing monomer (b) may further contain polymers other than polymer (b). Examples of polymers other than polymer (b) include polymers derived from acrylic polymerizable compounds and polymers derived from epoxy polymerizable compounds. The acrylic polymerizable compounds and epoxy polymerizable compounds are the same as those described above for the cured resin layer (A).

[0071] In the cured resin layer (B) 30, the proportion of polymer (b) to the total polymer is preferably 50% by mass or more, more preferably 60% by mass, and even more preferably 70% by mass or more, from the viewpoint of more reliably obtaining the effects of the present invention. Alternatively, the proportion of polymer (b) to the total polymer can be 100% by mass (i.e., the polymer in the cured resin layer (B) 30 consists only of polymer (b)). The above-mentioned proportion of polymer can be calculated from the mass ratio of monomers.

[0072] (Method for recovering the base material layer) A method for recovering the base material layer according to one embodiment of the present invention (hereinafter sometimes referred to as "the recovery method of this embodiment") is a method for recovering the base material layer from a support on which the base material layer is temporarily fixed. The recovery method of this embodiment includes at least a peeling step of peeling and removing the base material layer 1 from the laminate 100 described above, and a solvent contact step of contacting the peeled base material layer 1 with a solvent to remove any residue of the cured resin layer (B) 30 adhering to the base material layer 1.

[0073] <Peeling Process> As shown in Figure 5A, in the recovery method of this embodiment, the peeling process involves peeling and removing the base material layer 1 from the laminate 100 described above. In the peeling process, since the laminate 100 has a predetermined layer structure, the base material layer 1 can be easily peeled off without damaging it.

[0074] Such peeling can be performed, for example, by mechanically separating the base material layer 1 in the lamination direction (the direction that separates each layer) while the support 10 is fixed and held in place. Alternatively, during or prior to peeling, cuts may be made in the side surface of the cured resin layer (B) 30 using a knife-edge jig or the like.

[0075] <Solvent Contact Process> As shown in Figure 5A, the substrate layer 1 after the peeling process may have residue 35 of the cured resin layer (B) 30 attached to it. Therefore, in the recovery method of this embodiment, as a solvent contact process, the peeled substrate layer 1 is brought into contact with a solvent.

[0076] Examples of solvents include pure water, ethanol, cyclohexane, isopropyl alcohol, and any mixture of two or more of these.

[0077] The method of contacting the substrate layer 1 with the solvent is not particularly limited, but as shown in Figure 5B, immersion of the substrate layer 1 in the solvent 60 is preferred. The contact time with the solvent 60 is not particularly limited, but from the viewpoint of removing the residue 35 more efficiently and reliably, 5 to 120 minutes is preferred, 15 to 90 minutes is more preferred, and 30 to 60 minutes is even more preferred.

[0078] Upon contact with the solvent 60, the residue 35 adhering to the substrate layer 1 undergoes water absorption (liquid absorption) and swelling due to the polymer (b) (see Figure 5C), and is easily removed from the substrate layer 1.

[0079] In the solvent contact process, to further enhance the removal effect of residue 35, ultrasonic waves may be applied to the substrate layer 1 in contact with the solvent 60.

[0080] As described above, according to the recovery method of this embodiment, by using the laminate 100 described above and combining mechanical peeling (peeling process) and liquid peeling (solvent contact process), the substrate layer 1 from which the residue 35 has been removed can be easily recovered without damage. Furthermore, the recovery method of this embodiment has advantages such as low load on the substrate layer 1 such as a wafer, low contamination, and minimal impact on the back surface of the substrate layer 1 during processing.

[0081] Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0082] (Comparative Example 1) A glass material (glass substrate) was prepared as a support and a silicon wafer as a base layer. An uncured composition (A) was used to form the cured resin layer (A) by adding a photopolymerization initiator (Irg184) at a ratio of 1% by mass to TMPTA (trimethylolpropane triacrylate) monomer. The uncured composition (A) was filled between the support and the base layer. Then, the uncured composition (A) was cured by irradiating it with 365 nm LED ultraviolet light. In this way, a laminate (a laminate in which the base layer is temporarily fixed to the support) was obtained, comprising a support, a cured resin layer (A) directly formed on its surface, and a base layer directly placed thereon.

[0083] (Comparative Example 2) A glass material (glass substrate) was prepared as a support, and a silicon wafer was prepared as a base material layer. Further, an uncured composition (A) (including silicone addition) obtained by adding a photopolymerization initiator (Irg184) to a TMPTA monomer at a ratio of 1% by mass was used for forming the cured resin layer (A). Further, an uncured composition (B') obtained by adding a photopolymerization initiator (Irg184) to a TMPTA monomer at a ratio of 1% by mass was used for forming the cured resin layer (B'). The water absorption rate of the polymer formed by polymerization of the TMPTA monomer when immersed in water at 25°C for 120 minutes is less than 5%. The cured resin layer (A) was formed on the support using the uncured composition (A). Next, the base material layer was disposed on the cured resin layer (A) on the support so as to sandwich the uncured composition (B'). Then, LED ultraviolet light of 365 nm was irradiated to cure the uncured composition (B'). In this way, a laminate including a support, a cured resin layer (A) directly formed on its surface, a cured resin layer (B') directly disposed thereon, and a base material layer directly disposed thereon (a laminate in which the base material layer is temporarily fixed to the support) was obtained.

[0084] (Example 1) A glass material (glass substrate) was prepared as a support, and a silicon wafer was prepared as a base material layer. Further, an uncured composition (A) (including silicone addition) obtained by adding a photopolymerization initiator (Irg184) to a TMPTA monomer at a ratio of 1% by mass was used for forming the cured resin layer (A). Further, for forming the cured resin layer (B), a monomer (b1) (manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Ester AT-20E", represented by the following formula (1), in the formula (1), R is -CH ２ -CH ２ -O- represents, and the sum of l, m and n is approximately 20.) 70% by mass, and an uncured composition (B) obtained by adding a photopolymerization initiator (Irg184) to a monomer composition of 30% by mass of PET A (pentaerythritol tetraacrylate) at a ratio of 1% by mass was used. The water absorption rate of the polymer formed by polymerization of the monomer (b1) when immersed in water at 25°C for 120 minutes is 5% or more. Also, the water absorption rate of the polymer formed by polymerization of PET A when immersed in water at 25°C for 120 minutes is 1% or less.

[0085] A cured resin layer (A) was formed on the support using the uncured composition (A). Next, the substrate layer was placed on the cured resin layer (A) on the support so as to sandwich the uncured composition (B). Then, the uncured composition (B) was cured by irradiating it with 365 nm LED ultraviolet light. In this way, a laminate (a laminate in which the substrate layer is temporarily fixed to the support) was obtained, comprising a support, a cured resin layer (A) directly formed on its surface, a cured resin layer (B) directly placed on top of the cured resin layer (A), and a substrate layer directly placed on top of the cured resin layer (A).

[0086] (Example 2) A glass material (glass substrate) was prepared as the support and a silicon wafer as the base layer. The same uncured composition (A) (including silicone additive) as in Example 1 was used to form the cured resin layer (A). The same uncured composition (B) as in Example 1 was used to form the cured resin layer (B). The support was subjected to a silane treatment. Next, the support was placed on a mold having a fine uneven structure on its surface, so as to sandwich the uncured composition (A) and so as to the silane-treated surface of the support in contact with the uncured composition (A). Next, the uncured composition (A) was cured by irradiation with ultraviolet light, thereby forming a cured resin layer (A) having a fine uneven structure on the support. Next, the support was peeled off the mold. Next, a 10 nm thick Si film (inorganic film) was formed on the surface of the fine uneven structure of the cured resin layer (A) formed on the support by a vacuum process. Next, the substrate layer was placed on the cured resin layer (A) of the support so as to sandwich the uncured composition (B). Then, the uncured composition (B) was cured by irradiating it with 365 nm LED ultraviolet light. In this way, a laminate (a laminate in which the substrate layer is temporarily fixed to the support) was obtained, comprising a support, a cured resin layer (A) (equipped with a fine uneven structure and an inorganic film) directly formed on its surface, a cured resin layer (B) directly placed thereon, and a substrate layer directly placed thereon.

[0087] Next, the laminates obtained in each example were evaluated as follows.

[0088] <Evaluation 1: Evaluation of whether or not damage occurs during delamination> For each example of the laminate, the support was held under vacuum on a suction table. In this state, the base layer was mechanically delaminated in the lamination direction using a sharp knife-edge jig. If the base layer could be delaminated without cracking, it was evaluated as A; if the base layer cracked, it was evaluated as B. The results are shown in Table 1.

[0089] <Evaluation 2: Evaluation of the possibility of removing residue adhering to the substrate layer> The substrate layer peeled off in Evaluation 1 had residue from the cured resin layer ((A), (B'), or (B)) that had been in direct contact with it. Therefore, for each case in which the substrate layer could be peeled off without cracking in Evaluation 1, we confirmed whether the residue adhering to the substrate layer could be removed by a solvent. Specifically, a tank filled with a solvent was prepared, and the peeled substrate layer was immersed in the solvent for 60 minutes. Evaluations were performed using both pure water as the solvent and a mixed solvent of ethanol and cyclohexane. Furthermore, an evaluation was also performed using pure water as the solvent and applying ultrasound during immersion. For the substrate layer after immersion, if the residue was removed, it was evaluated as A, and if the residue remained, it was evaluated as B. The results are shown in Table 1.

[0090]

[0091] Table 1 shows that in the embodiment in which the substrate layer is temporarily fixed to the support according to the present invention, the substrate layer is not damaged when peeled off from the support, and any residue adhering to the substrate layer after peeling can be easily removed with a solvent.

[0092] According to the present invention, it is possible to provide a method for temporarily fixing a substrate layer, such as a wafer, to a support, which allows for easy removal of the substrate layer without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. Furthermore, according to the present invention, it is possible to provide a laminate in which a substrate layer, such as a wafer, is temporarily fixed to a support, which allows for easy removal of the substrate layer from the support without damaging it, and also allows for easy removal of any residue adhering to the substrate layer. Furthermore, according to the present invention, it is possible to provide a method for recovering a substrate layer using the above-described laminate, which allows for easy recovery of the substrate layer from which residue has been removed, without damaging it.

[0093] 1 Substrate layer 10 Support 20a Uncured composition 20 Cured resin layer (A) 21 Fine uneven structure 22 Inorganic film 30a Uncured composition containing monomer (b) 30 Cured resin layer (B) 35 Residue 50 Mold 60 Solvent 100 Laminate

Claims

1. A method for temporarily fixing a substrate layer to a support, wherein the support has a cured resin layer (A) directly formed on its surface, and the method comprises a lamination step of arranging the substrate layer on the cured resin layer (A) formed on the support so as to sandwich a composition containing monomer (b), and a curing step of curing the composition containing monomer (b) so as to form a cured resin layer (B) and temporarily fixing the substrate layer to the support, wherein the monomer (b) is a monomer whose water absorption rate is 5% or more when the polymer formed by polymerization is immersed in water at 25°C for 120 minutes.

2. The temporary fixing method according to claim 1, wherein the cured resin layer (A) has a fine uneven structure on the surface opposite to the surface in contact with the support.

3. The temporary fixing method according to claim 2, wherein the cured resin layer (A) comprises an inorganic film on the surface of the fine uneven structure.

4. A laminate comprising: a support; a cured resin layer (A) directly formed on the surface of the support; a cured resin layer (B) on the cured resin layer (A); and a base layer on the cured resin layer (B), wherein the cured resin layer (B) contains a polymer (b) having a water absorption rate of 5% or more when immersed in water at 25°C for 120 minutes.

5. The laminate according to claim 4, wherein the cured resin layer (A) has a fine uneven structure on the surface opposite to the surface in contact with the support.

6. The laminate according to claim 5, wherein the cured resin layer (A) comprises an inorganic film on the surface of the fine uneven structure.

7. A method for recovering a substrate layer from a support on which the substrate layer is temporarily fixed, comprising: a peeling step of peeling and removing the substrate layer from a laminate according to any one of claims 4 to 6; and a solvent contact step of contacting the peeled substrate layer with a solvent to remove any residue of the cured resin layer (B) adhering to the substrate layer.

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