Temporary adhesive for wafer processing, wafer laminate, and method for producing thin wafers

Abstract

The present invention is a temporary adhesive for wafer processing, which is used for temporarily bonding a wafer to a support. This temporary adhesive for wafer processing is composed of a curable silicone resin composition which can be cured by a hydrosilylation reaction. This curable silicone resin composition is a temporary adhesive for wafer processing, which characteristically contains an organopolysiloxane that has in each molecule only one alkenyl group or only one silicon atom-bonded hydrogen atom (SiH group). It is thereby possible to provide a temporary adhesive for wafer processing, a wafer laminate, and a method for producing thin wafers using same, which support an improved productivity for thin wafers, wherein, inter alia, an adequate substrate retention is exhibited post-bonding even when a substrate with high level differences is used; a high process compatibility is exhibited with wafer backside grinding processes, TSV formation processes, and wafer backside wiring processes; facile peeling is exhibited in peeling processes even after passage post-bonding through a lengthy high-temperature heating process in air; and the residue on the substrate post-peeling exhibits an excellent cleanability.

Description

Temporary adhesive for wafer processing, wafer stack, and method for manufacturing thin wafer

[0001] The present invention relates to a temporary adhesive for wafer processing, a wafer laminate, and a method for manufacturing a thin wafer.

[0002] Three-dimensional semiconductor packaging has become essential for achieving ever higher density and capacity. Three-dimensional packaging technology is a semiconductor fabrication technology in which a single semiconductor chip is thinned and then stacked in multiple layers while connecting the chips with through silicon vias (TSVs). To achieve this, a substrate on which a semiconductor circuit is formed must be thinned by grinding the non-circuit-forming surface (also referred to as the "backside"), and then electrodes, including TSVs, must be formed on the backside. Conventionally, in the backside grinding process of a silicon substrate, a backside protective tape is attached to the side opposite the grinding surface to prevent wafer damage during grinding. However, this tape uses an organic resin film as a support base, and while it is flexible, it lacks strength and heat resistance, making it unsuitable for the TSV formation process or the backside wiring layer formation process.

[0003] Therefore, a system has been proposed in which a semiconductor substrate is bonded to a support such as silicon or glass via an adhesive layer, thereby being able to withstand the processes of back grinding, TSV formation, and back electrode formation. The important thing here is the adhesive layer used when bonding the substrate to the support. This must be able to bond the substrate to the support without any gaps, be durable enough to withstand subsequent processes, and furthermore, be able to easily peel the thin wafer from the support at the end. Because this is the final peeling, this adhesive layer is also referred to as a temporary adhesive layer in this specification.

[0004] Previously known temporary adhesive layers and their peeling methods include a technique in which high-intensity light is irradiated onto an adhesive containing a light-absorbing substance to decompose the adhesive layer and thereby peel the adhesive layer from the support (Patent Document 1), and a technique in which a heat-fusible hydrocarbon compound is used as the adhesive and bonding and peeling are performed in a heated, molten state (Patent Document 2). The former technique requires expensive equipment such as a laser and has problems such as a long processing time per substrate. While the latter technique is simple because it is controlled only by heating, its thermal stability at temperatures above 200°C is insufficient, limiting its range of application. Furthermore, these temporary adhesive layers are not suitable for forming a uniform film thickness on high-step substrates and for complete adhesion to the support.

[0005]

[0004] Also, a technology using a silicone adhesive as a temporary adhesive layer has been proposed. This involves adhering a substrate to a support using an addition-curing silicone adhesive, and then separating the substrate from the support by immersing it in a chemical that dissolves or decomposes the silicone resin (Patent Document 3). Therefore, peeling requires a very long time, making it difficult to apply to actual manufacturing processes. Furthermore, after peeling, it also requires a long time to clean the silicone adhesive remaining on the substrate as a residue, which poses a problem in terms of cleaning removability.

[0006] To address the above-mentioned issues, a technology using a curable silicone composition containing a non-functional polyorganosiloxane as a temporary adhesive layer has been previously known (Patent Documents 4 and 5). This composition bonds a substrate and a support via a temporary adhesive layer, thereby achieving adhesion between the substrate and the temporary adhesive layer that can withstand substrate processing. Furthermore, when the support is peeled from the substrate, the temporary adhesive layer can be selectively peeled off while remaining adhered to the support, so that almost no temporary adhesive layer remains on the substrate after peeling. This significantly improves the washability of the substrate after peeling, thereby satisfying both the above-mentioned issues of peelability and washability. However, depending on the type of substrate with high step height, selective peeling from the substrate and the temporary adhesive layer is not possible, resulting in problems such as some temporary adhesive remaining on the substrate, resulting in long cleaning times for the residue. Furthermore, peeling a thinned substrate from the support after a long, high-temperature thermal process can lead to an abnormality in which the substrate cracks, so an urgent solution was needed.

[0007] Japanese Patent Application Laid-Open No. 2004-64040 Japanese Patent Application Laid-Open No. 2006-328104 U.S. Patent No. 7,541,264 WO2021-112070 WO2021-220929

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide a temporary adhesive for wafer processing, a wafer laminate, and a method for manufacturing thin wafers using the same, which have sufficient substrate retention after bonding even when using a substrate with a high step difference, are highly process-compatible with the wafer backside grinding process, TSV formation process, and wafer backside wiring process, are easy to peel in the peeling process even after undergoing a high-temperature, long-term thermal process in air after bonding, and have excellent residue cleanability on the substrate after peeling, thereby leading to improved productivity of thin wafers, such as:

[0009] In order to solve the above problems, the present invention provides a temporary adhesive for wafer processing, for temporarily bonding a wafer to a support, characterized in that the temporary adhesive for wafer processing comprises a curable silicone resin composition that can be cured by a hydrosilylation reaction, and the curable silicone resin composition contains an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule.

[0010] Such a curable silicone resin composition exhibits sufficient substrate retention after bonding, even when a substrate with a large step is used, is highly compatible with the wafer backside grinding process, TSV formation process, and wafer backside wiring process, is easy to peel in the peeling process even after undergoing a high-temperature, long-term thermal process in air after bonding, and is also excellent in terms of the ability to clean residues on the substrate after peeling, and is particularly able to improve the heat resistance of the resin.

[0011] Furthermore, the curable silicone resin composition preferably contains: (A) 100 parts by mass of an organopolysiloxane having two or more alkenyl groups per molecule; (B) 0.1 to 100 parts by mass of an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule; (C) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to a silicon atom (SiH group) per molecule, in an amount such that the sum of the SiH groups in components (B) and (C) to the sum of the alkenyl groups in components (A) and (B) is 0.3 to 5, in terms of the molar ratio; (D) 0.1 to 200 parts by mass of a non-functional organopolysiloxane; and (E) a hydrosilylation reaction catalyst in an amount of 0.1 to 5,000 ppm, calculated as the metal atom weight, relative to the total mass of components (A), (B), (C), and (D).

[0012] Such a curable silicone resin composition is preferable as a temporary adhesive for wafer processing.

[0013] In this case, it is preferable that the organopolysiloxane containing two or more alkenyl groups in one molecule of component (A) also contains at least one aryl group.

[0014] Such component (A) can be used as the curable silicone resin composition.

[0015] The non-functional organopolysiloxane of component (D) is preferably a dimethylpolysiloxane in which the viscosity of a 30% by weight toluene solution at 25°C is 100 to 500,000 mPa·s.

[0016] Such a viscosity is preferable from the viewpoints of workability of the composition, applicability to equipment, mechanical properties of the drop, peelability of the support, and the like.

[0017] Furthermore, it is preferable that the curable silicone resin composition containing the components (A) to (E) further contains a hydrosilylation reaction inhibitor as component (F) in an amount of 0.001 to 10 parts by mass, based on the total mass of the components (A), (B), and (C).

[0018] By including the component (F), thickening and gelation of the curable silicone resin composition can be prevented.

[0019] It is preferable that the organopolysiloxane contains only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) located in either a side chain or at the terminal per molecule.

[0020] By including such an organopolysiloxane in the curable silicone resin composition, the heat resistance of the resin can be further improved.

[0021] The curable silicone resin composition is preferably one that can be cured by either light or heat, or both.

[0022] Such a curable silicone resin composition can be made into a composition that can be cured by either light or heat, or both, through the hydrosilylation reaction of the component (E) used.

[0023] After the curable silicone resin composition is cured, it is preferable that the 180° peel strength of a 25 mm wide test piece from a silicon substrate at 25° C. is 2 gf or more and 100 gf or less.

[0024] If the 180° peel force is 2 gf or more, there is no risk of the wafer slipping during wafer grinding, and if it is 100 gf or less, the wafer can be easily peeled.

[0025] After curing, the curable silicone resin composition preferably has a storage modulus at 25° C. of 1,000 Pa or more and 1,000 MPa or less.

[0026] If the storage modulus is 1,000 Pa or more, the film formed is strong and there is no risk of wafer misalignment or associated wafer cracking during wafer grinding, and if the storage modulus is 1,000 MPa or less, deformation stress during wafer thermal processing such as CVD can be alleviated, and the film is stable even during thermal processing of the wafer.

[0027] Furthermore, the present invention provides a method for manufacturing a thin wafer, comprising the steps of: (a) releasably adhering the circuit-forming surface of a wafer having a circuit-forming surface on its front side and a non-circuit-forming surface on its back side to a support using the above-described temporary adhesive for wafer processing to form a wafer laminate; (b) curing the temporary adhesive; (c) grinding or polishing the non-circuit-forming surfaces of the wafers in the wafer laminate; (d) processing the non-circuit-forming surfaces of the wafers; and (e) peeling the processed wafers from the support.

[0028] By such a method for producing a thin wafer, the temporary adhesive for wafer processing can be used to temporarily bond a wafer having semiconductor circuits and the like to a support.

[0029] The present invention further provides a wafer laminate comprising a support, a temporary adhesive layer obtained from the above-mentioned temporary adhesive for wafer processing laminated thereon, and a wafer having a circuit-forming surface on its front side and a circuit-free surface on its back side, wherein the temporary adhesive layer is releasably adhered to the front side of the wafer.

[0030] Use of such a wafer stack can lead to improved productivity in thin wafers.

[0031] As described above, the temporary adhesive for wafer processing of the present invention can improve the heat resistance of the resin by using a curable silicone resin composition containing an organopolysiloxane having only one alkenyl group or only one hydrogen atom (SiH group) bonded to a silicon atom per molecule. This stabilizes the peelability between the substrate and the support, making it possible to easily peel the substrate from the support, especially even when exposed to high temperatures of 200°C or higher for long periods of time after bonding, and also provides excellent residue cleanability after peeling. Therefore, it can be applied to a wide range of semiconductor film formation processes, has excellent CVD (chemical vapor deposition) resistance, and can form a temporary adhesive layer with high film thickness uniformity even on wafers with steps, making it easy to produce thin wafers that are prone to cracking. According to the thin wafer manufacturing method of the present invention, thin wafers having through-hole electrode structures or bump connection structures can be easily manufactured.

[0032] As mentioned above, in the technology using a curable silicone composition for the temporary adhesive layer, depending on the type of substrate with a high step height, selective peeling from between the substrate and the temporary adhesive layer is not possible, and some of the temporary adhesive remains on the substrate, resulting in problems such as the need for a long time to clean off the residue. Furthermore, peeling the thinned substrate from the support after a long-term thermal process at high temperature can lead to an abnormality in which the substrate cracks, and therefore an immediate solution was needed.

[0033] As a result of extensive research into the above-mentioned problems, the present inventors have discovered that the use of a curable silicone resin composition containing a specific organopolysiloxane as a temporary adhesive for wafer processing can improve the heat resistance of the resin. They have also discovered that a temporary adhesive layer with high film thickness uniformity can be formed even on wafers with steps, making it possible to easily manufacture thin wafers that are prone to cracking, and have completed the present invention.

[0034] That is, the present invention provides a temporary adhesive for wafer processing, for temporarily bonding a wafer to a support, characterized in that the temporary adhesive for wafer processing comprises a curable silicone resin composition that can be cured by a hydrosilylation reaction, and the curable silicone resin composition contains an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule.

[0035] The present invention will be described in detail below, but the present invention is not limited thereto.

[0036] [Temporary adhesive for wafer processing] The temporary adhesive for wafer processing of the present invention comprises a curable silicone resin composition containing an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule. In view of its applicability to silicon wafers and the like having steps, a silicone resin composition having good spin-coatability is preferably used as the temporary adhesive for wafer processing.

[0037] Such a curable silicone resin composition preferably contains, for example, the following components (A) to (E). The hydrosilylation reaction catalyst of component (E) used can make the composition curable by either light or heat, or both. (A) an organopolysiloxane having two or more alkenyl groups per molecule: 100 parts by mass, (B) an organopolysiloxane having only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule: 0.1 to 100 parts by mass, (C) an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (SiH groups) per molecule: such that the sum of the SiH groups in components (B) and (C) to the sum of the alkenyl groups in components (A) and (B) is 0.3 to 5, in terms of molar ratio, (D) a non-functional organopolysiloxane: 0.1 to 200 parts by mass, and (E) a hydrosilylation reaction catalyst: 0.1 to 5,000 ppm, calculated as metal atom weight, based on the total mass of components (A), (B), (C), and (D).

[0038] [Component (A)] Component (A) is an organopolysiloxane having two or more alkenyl groups per molecule. Examples of component (A) include linear or branched diorganopolysiloxanes containing two or more alkenyl groups per molecule, organopolysiloxanes containing two or more alkenyl groups and at least one aryl group per molecule, and organopolysiloxanes containing two or more alkenyl groups per molecule and having SiO ４／２ and organopolysiloxanes having a three-dimensional network structure with siloxane units (Q units) represented by units. Among these, diorganopolysiloxanes or organopolysiloxanes having a three-dimensional network structure with an alkenyl group content of 0.0001 to 3.0 mol / 100 g are preferred. In the present invention, the alkenyl group content represents the number of moles of alkenyl groups contained per 100 g.

[0039] Furthermore, component (A) is preferably an organopolysiloxane containing two or more alkenyl groups and at least one aryl group per molecule. The number of alkenyl groups per molecule of component (A) is preferably 2 to 1000, more preferably 2 to 800. The number of aryl groups per molecule is preferably 2 to 1000, more preferably 2 to 800.

[0040] Examples of such organopolysiloxanes include those represented by the following formulas (A-1), (A-2), and (A-3). These may be used alone or in combination of two or more.

[0041] In formulas (A-1) to (A-3), R １ ~R １６ are each independently a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon group. １ ~X ５ are each independently an alkenyl-containing monovalent organic group.

[0042] In formula (A-1), a and b each independently represent an integer of 0 to 3. In formulas (A-1) and (A-2), c １ , c ２ , d １and d ２ is 0≦c １ ≦100, 2≦c ２ ≦100, 0≦d １ ≦10,000 and 0≦d ２ is an integer that satisfies ≦10,000, provided that a+b+c １ a, b, c are ≧2. １ , c ２ , d １ and d ２ The alkenyl group content is preferably 0.0001 to 3.0 mol / 100 g.

[0043] In formula (A-3), e is an integer of 1 to 3. １ , f ２ and f ３ is (f ２ +f ３ ) / f １ is 0.3 to 4.0, and the alkenyl group content is 0.001 to 2.3 mol / 100 g.

[0044] The monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon group preferably has 1 to 10 carbon atoms, and examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, and n-hexyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl and tolyl. Of these, alkyl groups such as methyl or phenyl are preferred.

[0045] The alkenyl-containing monovalent organic group is preferably one having 2 to 10 carbon atoms, and examples thereof include alkenyl groups such as vinyl, allyl, hexenyl, and octenyl; (meth)acryloylalkyl groups such as acryloylpropyl, acryloylmethyl, and methacryloylpropyl; (meth)acryloxyalkyl groups such as acryloxypropyl, acryloxymethyl, methacryloxypropyl, and methacryloxymethyl; and alkenyl-containing monovalent hydrocarbon groups such as cyclohexenylethyl and vinyloxypropyl. Of these, vinyl is preferred from an industrial viewpoint.

[0046] In formula (A-1), a and b are each independently an integer of 0 to 3, but if a is 1 to 3, the molecular chain terminals are blocked with alkenyl groups, and the highly reactive molecular chain terminal alkenyl groups enable the reaction to be completed in a short time, which is preferable. Furthermore, from an industrial perspective, it is preferable for a to be 1. The alkenyl group-containing diorganopolysiloxane represented by formula (A-1) or (A-2) is preferably in the form of an oil or a crude rubber.

[0047] The organopolysiloxane represented by formula (A-3) is SiO ４／２ It contains units and has a three-dimensional network structure. In formula (A-3), each e is independently an integer of 1 to 3, but from an industrial viewpoint, it is preferably 1 from the viewpoint of cost. Furthermore, the product of the average value of e and the alkenyl group content is preferably 0.001 to 7.0 mol / 100 g, and more preferably 0.001 to 2.3 mol / 100 g. The organopolysiloxane represented by formula (A-3) may be used as a solution dissolved in an organic solvent.

[0048] The number average molecular weight (Mn) of the organopolysiloxane of component (A) is preferably 100 to 1,000,000, and more preferably 1,000 to 100,000. Mn within this range is preferable in terms of workability associated with the viscosity of the composition and processability associated with the storage modulus after curing. In the present invention, Mn is a polystyrene-equivalent value measured by gel permeation chromatography using toluene as a solvent.

[0049] The component (A) may be used alone or in combination of two or more. It is particularly preferable to use a combination of an organopolysiloxane represented by formula (A-1) and an organopolysiloxane represented by formula (A-3). In this case, the amount of the organopolysiloxane represented by formula (A-3) used is preferably 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass, per 100 parts by mass of the organopolysiloxane represented by formula (A-1). The upper limit of the amount used is preferably 5,000 parts by mass, more preferably 3,000 parts by mass, and even more preferably 2,000 parts by mass. The lower limit is preferably 0.5 parts by mass, more preferably 1.0 part by mass.

[0050] [Component (B)] Component (B) is an organopolysiloxane in which, per molecule, there is exactly one alkenyl group or exactly one silicon-bonded hydrogen atom (SiH group), located either on a side chain or at the end.

[0051] Examples of such organopolysiloxanes include those represented by the following formula (B-1) or (B-2): These may be used alone or in combination of two or more.

[0052] In formula (B-1) or (B-2), R １７ ~R ２５ are each independently a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon group. １ ~Y ３ are each independently an alkenyl-containing monovalent organic group, a hydrogen atom, or an organohydrogenpolysiloxane containing one hydrogen atom bonded to a silicon atom (SiH group).

[0053] In formula (B-1), g+h=1 is satisfied, and i is an integer that satisfies 0≦i≦10,000. g, h, and i preferably provide an alkenyl group or SiH group content of 0.0001 to 0.7 mol / 100 g.

[0054] In formula (B-2), j １ and j ２ is (j ２ +1) / j １ is 0.3 to 4.0, and the alkenyl group or SiH group content is 0.0001 to 0.3 mol / 100 g.

[0055] The monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon group preferably has 1 to 10 carbon atoms, and examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, and n-hexyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl and tolyl. Of these, alkyl groups such as methyl or phenyl are preferred.

[0056] The alkenyl-containing monovalent organic group is preferably one having 2 to 10 carbon atoms, and examples thereof include alkenyl groups such as vinyl, allyl, hexenyl, and octenyl; (meth)acryloylalkyl groups such as acryloylpropyl, acryloylmethyl, and methacryloylpropyl; (meth)acryloxyalkyl groups such as acryloxypropyl, acryloxymethyl, methacryloxypropyl, and methacryloxymethyl; and alkenyl-containing monovalent hydrocarbon groups such as cyclohexenylethyl and vinyloxypropyl. Of these, vinyl is preferred from an industrial viewpoint.

[0057] As the organopolysiloxane in which the hydrogen atom bonded to the silicon atom (SiH group) is located either on a side chain or at a terminal, Y １ ~Y ３ is an organohydrogenpolysiloxane containing a hydrogen atom or one hydrogen atom bonded to a silicon atom, but from an industrial viewpoint, a hydrogen atom is preferred.

[0058] The organopolysiloxane represented by formula (B-1), in which only one alkenyl group or silicon-bonded hydrogen atom (SiH group) is located in a side chain or at an end per molecule, is preferably in the form of an oil or a crude rubber.

[0059] The viscosity at 25°C of organopolysiloxanes containing only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule, either located on a side chain or at a terminal, of component (B) is preferably 1 to 5,000 mPa·s, and more preferably 5 to 500 mPa·s. The viscosity here was measured at 25°C in accordance with JIS Z 8803. The viscometer used may be selected appropriately depending on the viscosity; for example, an E-type viscometer (RE-85R manufactured by Toki Sangyo Co., Ltd.) is preferably used.

[0060] The number average molecular weight (Mn) of the organopolysiloxane of component (B) is preferably 2 to 10,000, and more preferably 2 to 1,000. An Mn within this range is preferable in terms of workability associated with the viscosity of the composition and processability associated with the storage modulus after curing.

[0061] Although two or more types of component (B) may be used in combination, it is preferable to use one type alone. In this case, the amount of component (B) used is preferably 0.1 to 1,000 parts by mass, and more preferably 0.1 to 100 parts by mass, per 100 parts by mass of component (A).

[0062] [Component (C)] Component (C) is a crosslinking agent and is an organohydrogenpolysiloxane having at least two, and preferably three or more, silicon-bonded hydrogen atoms (SiH groups) per molecule. The organohydrogenpolysiloxane may be linear, branched, or cyclic. The organohydrogenpolysiloxane may be used alone or in combination of two or more. The number of silicon-bonded hydrogen atoms (SiH groups) per molecule of component (C) is preferably 2 to 200, and more preferably 2 to 150.

[0063] The viscosity of the organohydrogenpolysiloxane of component (C) at 25°C is preferably 1 to 5,000 mPa·s, and more preferably 5 to 500 mPa·s. The viscosity here was measured at 25°C in accordance with JIS Z 8803. The viscometer used can be selected appropriately depending on the viscosity, but an E-type viscometer (RE-85R manufactured by Toki Sangyo Co., Ltd.) is preferably used, for example.

[0064] The Mn of the organohydrogenpolysiloxane of component (C) is preferably 100 to 100,000, and more preferably 500 to 10,000. An Mn within this range is preferable in terms of workability associated with the viscosity of the composition and processability associated with the storage modulus after curing.

[0065] Component (C) is preferably blended so that the molar ratio (SiH groups / alkenyl groups) of the total SiH groups in components (B) and (C) to the total alkenyl groups in components (A) and (B) is in the range of 0.3 to 10, more preferably 0.5 to 5.0. When the molar ratio is 0.3 or higher, the crosslink density is not reduced and problems such as the temporary adhesive layer not curing do not occur. Furthermore, when the molar ratio is 5 or lower, the crosslink density is not too high, sufficient adhesive strength and tack are obtained, and the usable life of the treatment solution can be extended. The molar ratio (SiH groups / alkenyl groups) was calculated from the measured value of SiH per 100 g (mol / 100 g) and the measured value of alkenyl groups per 100 g (mol / 100 g). The molar ratio (SiH groups / alkenyl groups) in the preparation examples is calculated using the following formula: [(SiH group content of POHS / 100) × amount of POHS added] / {[(alkenyl group content of PDMS / 100) × amount of PDMS added] + [(alkenyl group content of PVMS / 100) × amount of PVMS added]} (wherein POHS is organohydrogenpolysiloxane, PDMS is dimethylpolysiloxane, and PVMS is vinylmethylpolysiloxane having a resin structure.)

[0066] [Component (D)] Component (D) is a non-functional organopolysiloxane. Here, "non-functional" means that the molecule does not contain any reactive groups such as alkenyl groups, hydroxy groups, alkoxy groups, or epoxy groups bonded directly to silicon atoms or via any other group, or any hydrogen or halogen atoms bonded directly to silicon atoms.

[0067] Examples of such non-functional organopolysiloxanes include organopolysiloxanes having unsubstituted or substituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups, having 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms. Examples of such monovalent hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl and phenethyl. Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms such as chlorine, fluorine, and bromine. Examples of such groups include halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. The monovalent hydrocarbon group is preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group.

[0068] The molecular structure of the non-functional organopolysiloxane of component (D) is not particularly limited and may be linear, branched, cyclic, or any other structure. However, linear or branched organopolysiloxanes are preferred, and linear diorganopolysiloxanes in which the main chain is essentially composed of repeating diorganosiloxane units and both molecular chain terminals are capped with triorganosiloxy groups are preferred.

[0069] The viscosity (25°C) of the non-functional organopolysiloxane, a 30% by weight toluene solution, is preferably 100 to 500,000 mPa·s, more preferably 200 to 100,000 mPa·s, from the viewpoints of workability of the composition, coatability to substrates, mechanical properties of the cured product, and support releasability. A viscosity within this range is preferred because it has an appropriate molecular weight, preventing volatilization during heat curing of the silicone resin composition, providing sufficient effectiveness, preventing wafer cracking during wafer thermal processes such as CVD, and providing good workability and coatability. The viscosity here was measured at 25°C in accordance with JIS Z 8803. The viscometer used may be selected appropriately depending on the viscosity; for example, an E-type viscometer (RE-85R manufactured by Toki Sangyo Co., Ltd.) is preferably used.

[0070] Examples of the non-functional organopolysiloxane include dimethylsiloxane polymers capped at both molecular chain terminals with trimethylsiloxy groups, phenylmethylpolysiloxanes capped at both molecular chain terminals with trimethylsiloxy groups, 3,3,3-trifluoropropylmethylsiloxane polymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with trimethylsiloxy groups, dimethylsiloxane-3,3,3-trifluoropropylmethyl copolymers capped at both molecular chain terminals with trimethylsiloxy groups, and dimethylsiloxane-3,3,3-trifluoropropylmethyl copolymers capped at both molecular chain terminals with trimethylsiloxy groups. Examples of such copolymers include a methylphenylsiloxane-3,3,3-trifluoropropylmethyl copolymer capped with trimethylsiloxy groups, a dimethylsiloxane-3,3,3-trifluoropropylmethylsiloxane-methylphenylsiloxane copolymer capped at both molecular chain terminals with trimethylsiloxy groups, a dimethylpolysiloxane capped at both molecular chain terminals with dimethylphenylsiloxy groups, a methylphenylpolysiloxane capped at both molecular chain terminals with dimethylphenylsiloxy groups, and a dimethylsiloxane-methylphenylsiloxane copolymer capped at both molecular chain terminals with dimethylphenylsiloxy groups.

[0071] The non-functional organopolysiloxane of component (D) may be used alone or in combination of two or more. It is preferable that the non-functional organopolysiloxane is in the form of an oil or a crude rubber. The amount of component (D) is 0.1 to 200 parts by mass, preferably 1 to 100 parts by mass, per 100 parts by mass of component (A).

[0072] [Component (E)] Component (E) is a hydrosilylation catalyst, preferably a platinum group metal-based hydrosilylation catalyst. Component (E) is a catalyst that promotes the addition reaction between alkenyl groups in components (A) and (B) and hydrosilyl groups in components (B) and (C). Component (E) includes thermally activated hydrosilylation catalysts (E-1) that are activated by heat and photoactivated hydrosilylation catalysts (E-2) that are activated by light. These hydrosilylation catalysts are generally compounds of noble metals and are expensive, so relatively readily available platinum or platinum compounds are often used.

[0073] That is, the curable silicone resin composition is preferably one that can be cured by either light or heat, or both.

[0074] (E-1) Examples of thermally activated platinum compounds for hydrosilylation reaction catalysts include chloroplatinic acid or complexes of chloroplatinic acid with olefins such as ethylene, complexes of chloroplatinic acid with alcohols or vinylsiloxanes, and metallic platinum supported on silica, alumina, carbon, etc. As platinum group metal catalysts other than platinum compounds, rhodium, ruthenium, iridium, and palladium compounds are also known, such as RhCl(PPh ３ ) ３ , RhCl(CO)(PPh ３ ) ２ , Ru ３ (CO) １２ , IrCl(CO)(PPh ３ ) ２ , Pd(PPh ３ ) ４ In the above formula, Ph is a phenyl group.

[0075] (E-2) Photoactivatable Hydrosilylation Catalyst This photoactivatable hydrosilylation catalyst is activated by irradiation with light, particularly ultraviolet light with a wavelength of 300 to 400 nm, and promotes the addition reaction between alkenyl groups in components (A) and (B) and hydrosilyl groups in components (B) and (C). This promoting effect is temperature-dependent, with a higher promoting effect being obtained at higher temperatures. Therefore, after the preferred light irradiation, it is preferable to use the catalyst at an ambient temperature of 0 to 200°C, more preferably 10 to 100°C, in order to complete the reaction within an appropriate reaction time.

[0076] The ligand of this catalyst is preferably one that exhibits catalytic activity under UV light with medium to long wavelengths, from UV-B to UV-A, in order to prevent damage to the wafer. Examples of such ligands include cyclic diene ligands and β-diketonato ligands.

[0077] From the above, preferred examples of the photoactivatable hydrosilylation reaction catalyst include, for example, a cyclic diene ligand type catalyst, such as (η ５-cyclopentadienyl)tri(σ-alkyl)platinum(IV) complexes, particularly specifically (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethylethylplatinum(IV), (cyclopentadienyl)dimethylacetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), (dimethylphenylsilylcyclopentadienyl)trimethylplatinum(IV), and the like, and β-diketonato ligand type Examples of the platinum complex include β-diketonatoplatinum(II) or platinum(IV), particularly specifically trimethyl(acetylacetonato)platinum(IV), trimethyl(3,5-heptanedionato)platinum(IV), trimethyl(methylacetoacetate)platinum(IV), bis(2,4-pentanedionato)platinum(II), bis(2,4-hexanedionato)platinum(II), bis(2,4-heptanedionato)platinum(II), bis(3,5-heptanedionato)platinum(II), bis(1-phenyl-1,3-butanedionato)platinum(II), bis(1,3-diphenyl-1,3-propanedionato)platinum(II), and bis(hexafluoroacetylacetonato)platinum(II).

[0078] When using these catalysts, if they are solid catalysts, they can be used in a solid state, but to obtain a more uniform cured product, it is preferable to use them dissolved in a suitable solvent. In this case, the term "suitable solvent" means a solvent that is soluble in any or all of components (A), (B), and (C) and is suitable for the working environment and process.

[0079] The amount of component (E) added is an effective amount, typically 0.1 to 5,000 ppm, preferably 1 to 1,000 ppm, calculated as the metal atom weight relative to the total mass of components (A), (B), (C), and (D). A content of 0.1 ppm or more does not reduce the curability of the composition, nor does it reduce the crosslink density or holding power. A content of 5,000 ppm or less can suppress side reactions such as dehydrogenation during curing and also extend the usable life of the treatment solution. The compounding ratio of component (E-1) to component (E-2) is (E-1):(E-2) = 80:20 or 20:80, preferably 100:0 or 0:100. Component (E-1) alone can be heat-cured without the need for ultraviolet irradiation, while component (E-2) alone can be cured in a short time.

[0080] [Component (F)] The curable silicone resin composition may further include a reaction inhibitor as component (F), which is optionally added as needed to prevent thickening or gelation of the composition when preparing the composition or applying it to a substrate.

[0081] Examples of the reaction inhibitor include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclohexanol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butynyloxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinyldisiloxane, etc. Of these, 1-ethynylcyclohexanol and 3-methyl-1-butyn-3-ol are preferred.

[0082] When the curable silicone resin composition containing the components (A) to (E) also contains component (F), its content should be adjusted to an optimum amount for each component because controllability differs depending on the chemical structure, but considering its effects on curability, storage stability, and post-curing physical properties, it is preferably 0.001 to 10 parts by mass, and more preferably 0.01 to 10 parts by mass, relative to the total mass of components (A), (B), and (C). When the content of component (F) is within this range, the composition has a long usable life, long-term storage stability, and good curability and workability.

[0083] The curable silicone resin composition further contains R Ａ ３ SiO ０．５ Units (wherein R Ａ are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, and SiO ２ Contains units, SiO ２ R for units Ａ ３ SiO ０．５ The molar ratio of units (R Ａ ３ SiO ０．５ / SiO ２ Alternatively, an organopolysiloxane having a ρ=(R) / ρ=(R) of 0.3 to 1.8 may be added. The amount of such an organopolysiloxane added is preferably 0 to 500 parts by weight per 100 parts by weight of component (A).

[0084] To the curable silicone resin composition, known antioxidants such as phenol-based, quinone-based, and amine-based antioxidants can be added to improve heat resistance.

[0085] A filler such as silica may be added to the curable silicone resin composition in order to further increase the physical strength of the temporary adhesive layer obtained from the composition.

[0086] The curable silicone resin composition may be used in the form of a solution by adding a solvent for the purposes of improving workability and mixability by lowering the viscosity of the composition, adjusting the film thickness of the temporary adhesive layer, etc. The solvent used is not particularly limited as long as it can dissolve the components described above, but hydrocarbon solvents such as pentane, hexane, cyclohexane, isooctane, nonane, decane, p-menthane, pinene, isododecane, and limonene are preferred.

[0087] Examples of the method for forming the solution include a method in which the curable silicone resin composition is prepared and then a solvent is added at the end to adjust the viscosity to the desired level, and a method in which the highly viscous components (A), (B) and / or (C) are diluted with a solvent in advance to improve workability and mixability, and then the remaining components are mixed in. Furthermore, the mixing method for forming the solution can be selected appropriately based on the viscosity of the composition and workability, such as a shaking mixer, a magnetic stirrer, or various mixers.

[0088] The amount of solvent to be added may be set as appropriate from the viewpoints of adjusting the viscosity and workability of the composition, and the film thickness of the temporary adhesive layer, but is, for example, preferably 5 to 900 parts by mass, and more preferably 10 to 400 parts by mass, per 100 parts by mass of the curable silicone resin composition.

[0089] The temporary adhesive layer can be formed by applying the curable silicone resin composition onto a substrate by a method such as spin coating, roll coating, etc. Among these, when the temporary adhesive layer is formed on a substrate by a method such as spin coating, it is preferable to coat the curable silicone resin composition in the form of a solution.

[0090] From the viewpoint of coatability, the viscosity of the curable silicone resin composition in solution at 25°C is preferably 1 to 100,000 mPa·s, and more preferably 10 to 10,000 mPa·s. The viscosity here was measured at 25°C in accordance with JIS Z 8803. The viscometer used may be selected appropriately depending on the viscosity, but an E-type viscometer (RE-85R manufactured by Toki Sangyo Co., Ltd.) is preferably used, for example.

[0091] The 180° peel strength of the curable silicone resin composition at 25°C after curing, measured on a 25mm wide test piece (e.g., a glass test piece), is typically 2 gf to 100 gf, preferably 3 gf to 50 gf, and more preferably 5 gf to 30 gf. A strength of 2 gf or more eliminates the risk of wafer misalignment during wafer grinding, while a strength of 100 gf or less facilitates wafer peeling. There are several methods for measuring the 180° peel strength. For example, using an AUTOGRAPH (AG-1) manufactured by Shimadzu Corporation, 120 mm of the tape is peeled at 180° from one end of the tape at 25°C and a rate of 300 mm / min, and the average force applied (120 mm stroke x 5 times) can be taken as the peel strength of the silicone resin layer.

[0092] The curable silicone resin composition has a storage modulus at 25°C after curing of 1,000 Pa or more and 1,000 MPa or less, preferably 10,000 Pa or more and 100 MPa or less. If the storage modulus is 1,000 Pa or more, the film formed is strong, and there is no risk of wafer misalignment or associated wafer cracking during wafer grinding. If the storage modulus is 1,000 MPa or less, deformation stress during wafer thermal processes such as CVD can be alleviated, and the wafer is stable during thermal processes. There are several methods for measuring the storage modulus. For example, a glass wafer containing a silicone resin layer is sandwiched between 25 mmφ aluminum plates using an Ares G2 manufactured by TA Instruments, and the elastic modulus is measured at 25°C in such a state that a load of 50 gf is applied to the silicone resin layer, and the obtained elastic modulus value can be used as the storage modulus of the silicone resin layer.

[0093] When forming a laminate of substrate / temporary adhesive layer / support, the curable silicone resin composition can selectively control the interface at the time of peeling after forming the laminate, depending on whether the curable silicone resin composition is applied to the substrate side or the support side. In other words, when the composition is applied to the substrate and a bonded body is formed with the support and then peeled, selective peeling is possible between the substrate and the temporary adhesive layer. In this case, the temporary adhesive layer remains as a residue on the support, which simplifies the subsequent substrate cleaning process and is preferable in terms of improved workability. On the other hand, when the target to which the curable silicone resin composition is applied is changed to the support and the bonded body with the substrate is peeled, selective peeling is possible at the temporary adhesive layer / support interface. In this case, the residue of the temporary adhesive layer remains on the substrate side, which may lead to reduced workability in the subsequent substrate cleaning process. However, when applied to the support side, it is less susceptible to influences that may be caused by the substrate used, such as curing inhibition in the hydrosilylation reaction, and is therefore more likely to function as a stable temporary adhesive, which is preferable.

[0094] [Method for Manufacturing a Thin Wafer] The method for manufacturing a thin wafer of the present invention is characterized in that the temporary adhesive for wafer processing is used to temporarily bond a wafer having semiconductor circuits or the like to a support.

[0095] The method for producing a thin wafer of the present invention comprises the following steps (a) to (e): (a) releasably adhering the circuit-forming surface of a wafer having a circuit-forming surface on its front side and a non-circuit-forming surface on its back side to a support using the temporary adhesive for wafer processing to form a wafer laminate, (b) curing the temporary adhesive, (c) grinding or polishing the non-circuit-forming surfaces of the wafers in the wafer laminate, (d) processing the non-circuit-forming surfaces of the wafers, and (e) peeling the processed wafers from the support.

[0096] [Step (a)] Step (a) is a temporary bonding step in which the circuit-forming surface of a wafer having a circuit-forming surface on its front surface and a non-circuit-forming surface on its back surface is releasably bonded to a support using the temporary adhesive for wafer processing to form a wafer laminate.

[0097] Specifically, any one of the following methods is applied: a method of forming a temporary adhesive layer on the surface of the wafer using the temporary adhesive for wafer processing, and bonding the support and the surface of the wafer via the temporary adhesive layer; a method of forming a temporary adhesive layer on the surface of a support using the temporary adhesive for wafer processing, and bonding the support and the surface of the wafer via the temporary adhesive layer; or a method of forming temporary adhesive layers on both the surface of the wafer and the surface of the support using the temporary adhesive for wafer processing, and bonding the support and the surface of the wafer via the temporary adhesive layer.

[0098] Wafers applicable to the present invention are typically semiconductor wafers. Examples of the semiconductor wafer include not only silicon wafers but also germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. The thickness of the wafer is not particularly limited, but is typically 600 to 800 μm, more typically 625 to 775 μm.

[0099] The support may be a substrate such as a silicon wafer, a glass plate, or a quartz wafer, but is not limited to these. In the present invention, when the curable silicone resin composition is cured without being irradiated with light through the support, the support may not be light-transmitting. On the other hand, when the curable silicone resin composition is cured by being irradiated with light through the support, it is preferable to use a support that is light-transmitting.

[0100] The temporary adhesive layer may be formed by laminating a film formed from the curable silicone resin composition on a wafer or a support, or by applying the curable silicone resin composition by a method such as spin coating or roll coating. When the curable silicone resin composition is a solution containing a solvent, after application, the composition is prebaked in advance at a temperature of preferably 40 to 200°C, more preferably 50 to 150°C, depending on the evaporation conditions of the solvent, before use.

[0101] The temporary adhesive layer is preferably formed and used with a film thickness of 0.1 to 500 μm, preferably 1.0 to 200 μm. If the film thickness is 0.1 μm or more, when it is applied to a substrate, it can be applied to the entire substrate without leaving any uncoated areas. On the other hand, if the film thickness is 500 μm or less, it can withstand the grinding process when forming a thin wafer.

[0102] The method for bonding the support and the wafer surface via the temporary adhesive layer includes a method of uniformly pressing them together under reduced pressure, preferably in a temperature range of 10 to 200°C, more preferably 20 to 150°C.

[0103] The pressure when pressing the wafer on which the temporary adhesive layer has been formed and the support body together depends on the viscosity of the temporary adhesive layer, but is preferably 0.01 to 10 MPa, more preferably 0.1 to 1.0 MPa. If the pressure is 0.01 MPa or more, the circuit formation surface and the space between the wafer and the support body can be filled with the temporary adhesive layer, and if the pressure is 10 MPa or less, there is no risk of the wafer cracking or deterioration of the flatness of the wafer and the temporary adhesive layer, and subsequent wafer processing is good.

[0104] Wafer bonding can be performed using a commercially available wafer bonder, such as EVG520IS or 850TB manufactured by EVG, or XBS300 manufactured by SUSS MicroTec.

[0105] [Step (b)] Step (b) is a step of curing the temporary adhesive layer. In the case of a thermosetting silicone resin composition, after forming the wafer laminate, the temporary adhesive layer is cured by heating preferably at 50 to 300°C, more preferably at 100 to 200°C, preferably for 1 minute to 4 hours, more preferably for 5 minutes to 2 hours. In the case of a photocurable resin composition, after forming the wafer processed body (laminate substrate), light may be irradiated from the light-transmitting support side to photocure the temporary adhesive layer, or the wafer processed body (laminate substrate) may be formed using a photocurable silicone resin composition that has been irradiated with light in advance and then cured. The type of actinic ray used in this step is not particularly limited, but ultraviolet light is preferred, and ultraviolet light with a wavelength of 300 to 400 nm is more preferred. The ultraviolet irradiation dose (illuminance) is 100 mJ / cm as the integrated light amount.２ ~100,000mJ / cm ２ , preferably 500 mJ / cm ２ ~10,000mJ / cm ２ , more preferably 1,000 to 5,000 mJ / cm ２ In order to obtain good curability, it is desirable that the UV irradiation amount (illuminance) is equal to or greater than the lower limit of the above range, sufficient energy is obtained to activate the photoactivatable hydrosilylation reaction catalyst in the temporary adhesive layer, and a sufficient cured product can be obtained. On the other hand, if the UV irradiation amount (illuminance) is equal to or less than the upper limit of the above range, sufficient energy is irradiated onto the composition, and a sufficient cured product can be obtained without decomposition of the components in the polymer layer or partial deactivation of the catalyst.

[0106] The ultraviolet radiation may be light having multiple emission spectra or light having a single emission spectrum. Furthermore, the single emission spectrum may be a broad spectrum in the range of 300 nm to 400 nm. Light having a single emission spectrum is light having a peak (i.e., maximum peak wavelength) in the range of 300 nm to 400 nm, preferably 350 nm to 380 nm. Examples of light sources for irradiating such light include ultraviolet light-emitting diodes (ultraviolet LEDs) and ultraviolet light-emitting semiconductor element light sources such as ultraviolet light-emitting semiconductor lasers.

[0107] Examples of light sources that irradiate light having multiple emission spectra include lamps such as metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, sodium lamps, low-pressure mercury lamps, high-pressure mercury lamps, and ultra-high-pressure mercury lamps; gas lasers such as nitrogen; liquid lasers using organic dye solutions; and solid-state lasers in which rare earth ions are incorporated into inorganic single crystals.

[0108] When the light has a peak in the wavelength region shorter than 300 nm in the emission spectrum, or when there is a wavelength in the wavelength region shorter than 300 nm that has an irradiance greater than 5% of the irradiance of the maximum peak wavelength in the emission spectrum (for example, when the emission spectrum is broad over a wide wavelength region), and when a substrate that is optically transparent to wavelengths shorter than 300 nm, such as a quartz wafer, is used as the support, it is preferable to remove light with wavelengths shorter than 300 nm using an optical filter in order to obtain a sufficient cured product. This reduces the irradiance of each wavelength in the wavelength region shorter than 300 nm to 5% or less, preferably 1% or less, more preferably 0.1% or less, and even more preferably 0%, of the irradiance of the maximum peak wavelength. When multiple peaks exist in the wavelength region from 300 nm to 400 nm in the emission spectrum, the peak wavelength showing the greatest absorbance among them is taken as the maximum peak wavelength. There are no particular limitations on the optical filter, as long as it cuts wavelengths shorter than 300 nm, and any known filter may be used. For example, a 365 nm bandpass filter or the like can be used. The illuminance and spectral distribution of ultraviolet light can be measured using a spectroradiometer, for example, USR-45D (Ushio Inc.).

[0109] The light irradiation device is not particularly limited, but for example, a spot type irradiation device, a surface type irradiation device, a line type irradiation device, a conveyor type irradiation device, or the like can be used.

[0110] When curing a photocurable silicone resin composition, the light irradiation time cannot be generally specified because it depends on the illuminance, but if the illuminance is adjusted so that it is, for example, 1 to 300 seconds, preferably 10 to 200 seconds, and more preferably 30 to 150 seconds, the irradiation time will be appropriately short and will not cause any particular problems in the work process. Furthermore, after light irradiation, the photocurable silicone resin composition will gel after 1 to 120 minutes, particularly 5 to 60 minutes. In this invention, gelation refers to a state in which the curing reaction of the photocurable silicone resin composition has partially progressed and the composition has lost its fluidity.

[0111] Furthermore, since the curing rate of the photocurable silicone resin composition after irradiation with light depends on the ambient temperature, it is preferable to leave the wafer processed body (laminate substrate) at a temperature of preferably 20 to 150°C, more preferably 30 to 100°C, from the viewpoint of improving workability.

[0112] [Step (c)] Step (c) is a step of grinding or polishing the non-circuit-forming surface of the wafer temporarily bonded to the support, that is, a step of grinding the backside of the wafer of the wafer laminate obtained in the above step to reduce the thickness of the wafer. There are no particular limitations on the method of grinding the backside of the wafer, and a known grinding method can be used. Grinding is preferably performed while cooling the wafer and grinding stone (diamond, etc.) by spraying water on them. An example of an apparatus for grinding the backside of the wafer is DAG-810 (trade name) manufactured by Disco Corporation. Alternatively, the backside of the wafer may be subjected to chemical mechanical polishing (CMP).

[0113] [Step (d)] Step (d) is a step of processing the non-circuit surface of the wafer laminate whose non-circuit surface has been ground in step (c). That is, it is a step of processing the non-circuit surface of the wafer of the wafer laminate thinned by backside grinding. This step includes various processes used at the wafer level. Examples include electrode formation, metal wiring formation, protective film formation, etc. More specifically, examples include conventionally known processes such as metal sputtering for forming electrodes, wet etching of the metal sputtered layer, pattern formation by applying, exposing, and developing a resist to serve as a mask for metal wiring formation, resist stripping, dry etching, metal plating formation, silicon etching for TSV formation, and oxide film formation on the silicon surface.

[0114] [Step (e)] Step (e) is a step of peeling the wafer processed in step (d) from the support, i.e., a step of peeling the wafer from the support after various processing has been performed on the thinned wafer and before dicing. This peeling step is generally carried out under relatively mild conditions, such as room temperature to about 60°C. Peeling methods include fixing one of the wafers or the support of the wafer stack horizontally and lifting the other at a certain angle from the horizontal direction, and attaching a protective film to the ground surface of the ground wafer and peeling the wafer and protective film from the wafer stack using a peel method. When the peeling step is carried out using these peeling methods, it is usually carried out at room temperature.

[0115] Furthermore, step (e) preferably includes the steps of: (e1) attaching a dicing tape to the wafer surface of the processed wafer; (e2) vacuum-adsorbing the dicing tape surface to an adsorption surface; and (e3) peeling the support from the processed wafer by peeling it off at an adsorption surface temperature in the range of 10 to 100° C. This allows the support to be easily peeled from the processed wafer, and also facilitates the subsequent dicing step.

[0116] After the step (e), it is preferable to carry out a step (f) of removing the temporary adhesive layer remaining on the circuit-forming surface of the peeled wafer. A portion of the temporary adhesive layer may remain on the circuit-forming surface of the wafer peeled from the support in the step (e), and the temporary adhesive layer can be removed by, for example, washing the wafer.

[0117] In this step (f), any cleaning liquid can be used as long as it dissolves the silicone resin of the temporary adhesive layer, and specific examples include pentane, hexane, cyclohexane, decane, isononane, p-menthane, pinene, isododecane, limonene, etc. These solvents may be used alone or in combination of two or more.

[0118] Furthermore, if the temporary adhesive layer is difficult to remove, a base or acid may be added to the cleaning solution. Examples of the base include amines such as ethanolamine, diethanolamine, triethanolamine, triethylamine, and ammonia; and ammonium salts such as tetramethylammonium hydroxide. Examples of the acid include organic acids such as acetic acid, oxalic acid, benzenesulfonic acid, and dodecylbenzenesulfonic acid. The amount of the base or acid added is preferably an amount that results in a concentration in the cleaning solution of 0.01 to 10% by mass, more preferably 0.1 to 5% by mass. Furthermore, an existing surfactant may be added to improve the removability of residual matter. The SPIS-TA-CLEANER series (manufactured by Shin-Etsu Chemical Co., Ltd.), which is available as a wafer cleaner, can also be suitably used.

[0119] Examples of methods for cleaning the wafer include a method of cleaning with a paddle using the cleaning liquid, a method of cleaning by spraying, and a method of immersing in a cleaning liquid tank. The temperature during cleaning is preferably 10 to 80° C., more preferably 15 to 65° C. If necessary, after dissolving the temporary adhesive layer with these cleaning liquids, the wafer may be finally rinsed with water or alcohol and then dried.

[0120] The thickness of the thin wafer obtained by the manufacturing method of the present invention is typically 5 to 300 μm, more typically 10 to 100 μm.

[0121] [Wafer laminate] The present invention can provide a wafer laminate comprising a support, a temporary adhesive layer obtained from the above-described temporary adhesive for wafer processing laminated thereon, and a wafer having a circuit-forming surface on its front surface and a circuit-free surface on its back surface, wherein the temporary adhesive layer is releasably adhered to the front surface of the wafer.

[0122] The present invention will be explained in more detail below with reference to Preparation Examples, Comparative Preparation Examples, Examples, and Comparative Examples, but the present invention is not limited to these Examples. The viscosity here was measured at 25°C in accordance with JIS Z 8803. The viscometer to be used may be selected appropriately depending on the viscosity, and for example, an E-type viscometer (RE-85R manufactured by Toki Sangyo Co., Ltd.) can be suitably used.

[0123] [1] Preparation of Curable Silicone Resin Solution [Preparation Example 1] A solution of 100 parts by mass of polydimethylsiloxane having an alkenyl content of 0.0336 mol / 100 g and a number average molecular weight (Mn) of 30,000 and 200 parts by mass of xylene was added with SiO ４／２ Units (Q units) 50 mol%, (CH ３ ) ３ SiO １／２ 48 mol% of units (M units) and (CH ２ =CH)(CH ３ ) ２ SiO １／２ Unit (M Ｖｉ A solution consisting of 50 parts by mass of vinylmethylpolysiloxane (Component A) having an alkenyl content of 0.0282 mol / 100 g and an Mn of 7,000, and consisting of 2 mol% of vinyl groups at one end, and 100 parts by mass of xylene, 5 parts by mass of vinyldimethylpolysiloxane (Component B) having an alkenyl content of 0.0125 mol / 100 g and an Mn of 8,000, and (CH ３ ) ２ SiO ２／２ Units (D units) 83.9 mol%, (CH ３ ) HSiO ２／２ Units (D Ｈ 25 parts by mass of an organohydrogenpolysiloxane (Component C) having a SiH group content of 0.222 mol / 100 g (expressed as 16.1 mol%) and an Mn of 2,400, 50 parts by mass of a dimethylpolysiloxane (Component D) terminated at both molecular chain ends with trimethylsiloxy groups and having a viscosity (25°C) of 30,000 mPa·s in a 30% by mass toluene solution, 120 parts by mass of xylene, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Further, 0.4 parts by mass of hydrosilylation reaction catalyst CAT-PL-5 (Component E) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare thermosetting silicone resin solution A1. The viscosity of resin solution A1 at 25°C was 2,400 mPa·s. The Si—H / Si—Vi (molar ratio) in this Preparation Example 1 was 1.2.

[0124] Preparation Example 2: A solution of 100 parts by mass of polydimethylsiloxane having an alkenyl content of 0.0336 mol / 100 g and a number average molecular weight (Mn) of 30,000 and 200 parts by mass of xylene was added with SiO ４／２ Units (Q units) 50 mol%, (CH ３ ) ３ SiO １／２ 48 mol% of units (M units) and (CH ２ =CH)(CH ３ ) ２ SiO １／２ Unit (M Ｖｉ A solution consisting of 50 parts by mass of vinylmethylpolysiloxane (Component A) having an alkenyl content of 0.0282 mol / 100 g and an Mn of 7,000, and consisting of 2 mol% (units) of vinylmethylpolysiloxane (Component A), 5 parts by mass of organohydrogenpolydimethylsiloxane (Component B) having one SiH group at one end, an SiH group content of 0.0100 mol / 100 g, and an Mn of 10,000, (CH ３ ) ２ SiO ２／２ Units (D units) 83.9 mol%, (CH ３ ) HSiO ２／２ Units (D Ｈ 35 parts by mass of an organohydrogenpolysiloxane (Component C) having a SiH group content of 0.222 mol / 100 g (expressed as 16.1 mol%) and an Mn of 2,400, 50 parts by mass of a dimethylpolysiloxane (Component D) terminated at both molecular chain ends with trimethylsiloxy groups and having a viscosity (25°C) of 1,000 mPa·s in a 30% by mass toluene solution, 120 parts by mass of xylene, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Further, 0.4 parts by mass of hydrosilylation reaction catalyst CAT-PL-5 (Component E) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare thermosetting silicone resin solution A2. The viscosity of resin solution A2 at 25°C was 1,200 mPa·s. The Si—H / Si—Vi (molar ratio) in this Preparation Example 2 was 1.6.

[0125] Preparation Example 3 A solution of 100 parts by mass of polydimethylsiloxane having a phenyl group content of 0.127 mol / 100 g, an alkenyl group content of 0.0248 mol / 100 g, an Mn of 30,000, and 200 parts by mass of xylene was added with SiO ４／２ Units (Q units) 50 mol%, (CH ３ ) ３ SiO １／２ 48 mol% of units (M units) and (CH ２ =CH)(CH ３ ) ２ SiO １／２ Unit (M Ｖｉ A solution consisting of 50 parts by mass of vinylmethylpolysiloxane (Component A) having a resin structure with an alkenyl group content of 0.0282 mol / 100 g and an Mn of 7,000, and consisting of 2 mol% vinyl groups (units) and 100 parts by mass of xylene, 5 parts by mass of vinyldimethylpolysiloxane (Component B) having an alkenyl group content of 0.0125 mol / 100 g and an Mn of 8,000, and having one vinyl group at one end, (CH ３ ) ２ SiO ２／２ Units (D units) 83.9 mol%, (CH ３ ) HSiO ２／２ Units (D Ｈ A solution consisting of 10 parts by mass of an organohydrogenpolysiloxane (Component C) having a SiH group content of 0.222 mol / 100 g (expressed as 16.1 mol%) and an Mn of 2,400, 50 parts by mass of a dimethylpolysiloxane (Component D) capped at both molecular chain ends with trimethylsiloxy groups and having a viscosity (25°C) of 100,000 mPa·s in a 30% by mass toluene solution, and 120 parts by mass of xylene, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Further, 0.4 parts by mass of hydrosilylation reaction catalyst CAT-PL-5 (manufactured by Shin-Etsu Chemical Co., Ltd., platinum concentration 1.0% by mass) (Component E) was added, and the mixture was filtered through a 0.2 μm membrane filter to prepare thermosetting silicone resin solution A3. The viscosity of resin solution A3 at 25°C was 3,300 mPa·s. In addition, the Si—H / Si—Vi (molar ratio) in Preparation Example 3 is 0.56.

[0126] Preparation Example 4 A solution of 100 parts by mass of polydimethylsiloxane having a phenyl group content of 0.127 mol / 100 g, an alkenyl group content of 0.0248 mol / 100 g, an Mn of 30,000, and 200 parts by mass of xylene was added with SiO ４／２ Units (Q units) 50 mol%, (CH ３ ) ３ SiO １／２ 48 mol% of units (M units) and (CH ２ =CH)(CH ３ ) ２ SiO １／２ Unit (M Ｖｉ A solution consisting of 50 parts by mass of vinylmethylpolysiloxane (Component A) having a resin structure with an alkenyl group content of 0.0282 mol / 100 g and an Mn of 7,000, and consisting of 2 mol% (units) of vinylmethylpolysiloxane, and 100 parts by mass of xylene; 5 parts by mass of organohydrogenpolydimethylsiloxane (Component B) having one SiH group at one end, an SiH group content of 0.0100 mol / 100 g, and an Mn of 10,000; ３ ) ２ SiO ２／２ Units (D units) 83.9 mol%, (CH ３ ) HSiO ２／２ Units (D Ｈ A solution consisting of 20 parts by mass of an organohydrogenpolysiloxane (Component C) having a SiH group content of 0.222 mol / 100 g (expressed as 16.1 mol%) and an Mn of 2,400, 50 parts by mass of a dimethylpolysiloxane (Component D) capped at both molecular chain ends with trimethylsiloxy groups and having a viscosity (25°C) of 30,000 mPa·s in a 30% by mass toluene solution, and 120 parts by mass of xylene, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Further, 0.4 parts by mass of hydrosilylation reaction catalyst CAT-PL-5 (manufactured by Shin-Etsu Chemical Co., Ltd., platinum concentration 1.0% by mass) (Component E) was added, and the mixture was filtered through a 0.2 μm membrane filter to prepare thermosetting silicone resin solution A4. The viscosity of resin solution A4 at 25°C was 2,500 mPa·s. In addition, the Si--H / Si--Vis (molar ratio) in Preparation Example 4 is 1.2.

[0127] [Preparation Example 5] Thermosetting silicone resin solution A5 was prepared in the same manner as in Preparation Example 1 above, except that a vinyldimethylpolysiloxane (alkenyl group content: 0.0125 mol / 100 g, Mn: 8,000, 5 parts by mass) having one vinyl group on a side chain (component B) was added instead of the vinyldimethylpolysiloxane (alkenyl group content: 0.0125 mol / 100 g, Mn: 8,000, 5 parts by mass) having one vinyl group on one terminal (component B). The viscosity of resin solution A5 at 25°C was 2,400 mPa s. The Si—H / Si—Vi (molar ratio) in Preparation Example 5 was 1.2.

[0128] [Preparation Example 6] A thermosetting silicone resin solution A6 was prepared in the same manner as in Preparation Example 2 above, except that an organohydrogenpolydimethylsiloxane having one SiH group on a side chain (SiH group content: 0.0100 mol / 100 g, Mn: 10,000, 5 parts by mass) (Component B) was added instead of the organohydrogenpolydimethylsiloxane having one SiH group on one end (SiH group content: 0.0100 mol / 100 g, Mn: 10,000, 5 parts by mass). The viscosity of resin solution A6 at 25°C was 1,200 mPa s. The Si—H / Si—Vi (molar ratio) in Preparation Example 6 was 1.6.

[0129] [Preparation Example 7] Photocurable silicone resin solution A7 was prepared in the same manner as in Preparation Example 1 above, except that the hydrosilylation catalyst CAT-PL-5 (0.4 parts by mass) (Component E) was replaced with a photoactivated hydrosilylation catalyst: a toluene solution of (methylcyclopentadienyl)trimethylplatinum(IV) (platinum concentration 1.0% by mass) (Component E) (0.4 parts by mass). The viscosity of resin solution A7 at 25°C was 2,400 mPa s. The Si-H / Si-Vis (molar ratio) in this Preparation Example 7 was 1.2.

[0130] [Preparation Example 8] Photocurable silicone resin solution A8 was prepared in the same manner as in Preparation Example 2 above, except that the hydrosilylation catalyst CAT-PL-5 (0.4 parts by mass) (Component E) was replaced with a photoactivated hydrosilylation catalyst; (methylcyclopentadienyl)trimethylplatinum(IV) toluene solution (platinum concentration 1.0% by mass) (Component E) (0.4 parts by mass). The viscosity of resin solution A8 at 25°C was 1,200 mPa s. The Si-H / Si-Vis (molar ratio) in this Preparation Example 8 was 1.6.

[0131] Comparative Preparation Example 1 A thermosetting silicone resin solution CA1 was prepared in the same manner as in Preparation Example 1 above, except that 5 parts by mass of vinyldimethylpolysiloxane (Component B) having an alkenyl group content of 0.0125 mol / 100 g and an Mn of 8,000 and having one vinyl group at one end was not added. The viscosity of resin solution CA1 at 25°C was 2,500 mPa s. The Si-H / Si-Vi (molar ratio) in this Comparative Preparation Example 1 was 1.2.

[0132] Comparative Preparation Example 2 In the above Preparation Example 1, instead of 5 parts by mass of vinyldimethylpolysiloxane (Component B) having an alkenyl group content of 0.0125 mol / 100 g and an Mn of 8,000, which has one vinyl group at one end, 5 parts by mass of vinyldimethylpolysiloxane having an alkenyl group content of 0.025 mol / 100 g and an Mn of 8,000, which has vinyl groups at both ends, was added to prepare a thermosetting silicone resin solution CA2. The viscosity of resin solution CA2 at 25°C was 2,500 mPa s. The Si-H / Si-Vi (molar ratio) in this Comparative Preparation Example 2 was 1.1.

[0133] Comparative Preparation Example 3: A thermosetting silicone resin solution CA3 was prepared in the same manner as in Preparation Example 2, except that 5 parts by mass of organohydrogenpolydimethylsiloxane (Component B) having a SiH group content of 0.0100 mol / 100 g and an Mn of 10,000, each containing one SiH group at one end, was not added. The viscosity of resin solution CA3 at 25°C was 1,300 mPa s. The Si—H / Si—Vi (molar ratio) in Comparative Preparation Example 3 was 1.6.

[0134] Comparative Preparation Example 4 In the above Preparation Example 2, instead of 5 parts by mass of organohydrogenpolydimethylsiloxane (Component B) having one SiH group at one end, a SiH group content of 0.0200 mol / 100 g, and an Mn of 10,000, 5 parts by mass of organohydrogenpolydimethylsiloxane having SiH groups at both ends, a SiH group content of 0.0400 mol / 100 g, and an Mn of 10,000 was added to prepare a thermosetting silicone resin solution CA4. The viscosity of resin solution CA4 at 25°C was 1,300 mPa s. The Si-H / Si-Vis (molar ratio) in this Comparative Preparation Example 4 was 1.6.

[0135] Comparative Preparation Example 5: A photocurable silicone resin solution CA5 was prepared in the same manner as in Preparation Example 5, except that 5 parts by mass of vinyldimethylpolysiloxane (Component B) having an alkenyl group content of 0.0125 mol / 100 g and an Mn of 8,000, each of which has one vinyl group at one end, was not added. The viscosity of resin solution CA5 at 25°C was 2,400 mPa s. The Si-H / Si-Vi (molar ratio) in Comparative Preparation Example 5 was 1.2.

[0136] [2] Preparation of Wafer Stack and Evaluation Thereof [Examples 1 to 8 and Comparative Examples 1 to 5] Curable silicone resin solutions A1 to A8 and CA1 to CA5 were each spin-coated onto a 200 mm diameter silicon wafer (thickness: 725 μm) having copper posts 10 μm high and 40 μm in diameter formed all over its surface, and heated in an oven at 100° C. for 2 minutes to form a temporary adhesive layer on the wafer bump-forming surface with the film thickness shown in Table 1 below. Using a 200 mm diameter glass wafer (thickness: 500 μm) as a support, the silicon wafer and glass wafer having the temporary adhesive layer were each bonded to the glass wafer using an EVG520IS wafer bonding device manufactured by EVG Corporation at 100° C. for 2 minutes, 10 －３The wafers were laminated by vacuum bonding under a pressure of 5 mbar or less and a load of 5 kN, followed by a curing step. The curing conditions were as follows: when a thermosetting silicone resin solution was used, the wafers were heated in an oven at 180°C for 1 hour; when a photocurable silicone resin solution was used, the wafers were cured by using a surface-irradiation type UV-LED (wavelength 365 nm) irradiator at 23°C and 100 mW / cm. ２ The test was carried out by irradiating the sample with light for 120 seconds at an illuminance of 1.0.

[0137] Thereafter, the obtained wafer laminate was subjected to various tests using the following test methods, the results of which are also shown in Table 1.

[0138] (1) Adhesion Test In the wafer laminate, the adhesion state of the wafer interface was visually confirmed from the glass support side, and when no abnormalities such as bubbles were found at the interface, it was evaluated as good and indicated by "○", and when abnormalities were found, it was evaluated as bad and indicated by "×".

[0139] (2) Backside Grinding Resistance Test Using the wafer stack, the backside of the silicon wafer was ground using a diamond grinding wheel in a grinder (DAG-810 manufactured by Disco Corporation). After grinding until the thickness of the substrate was 30 μm, the presence or absence of abnormalities such as cracks and peeling was examined using an optical microscope (100x magnification). When no abnormalities occurred, the result was evaluated as good and indicated by "○", and when abnormalities occurred, the result was evaluated as bad and indicated by "×".

[0140] (3) Heat Resistance Test (2) After the back grinding resistance test, the wafer stack was heated in an oven at 250°C for 1 hour, and then cooled to room temperature, after which the presence or absence of appearance abnormalities was visually inspected. When no appearance abnormalities occurred, the wafer was evaluated as good and indicated by "○", and when appearance abnormalities such as voids, wafer swelling, or wafer breakage occurred, the wafer was evaluated as bad and indicated by "×".

[0141] (4) Peelability test after heat resistance test: First, (3) the heat resistance test was performed on the wafer side of the wafer laminate. A dicing tape (ELP UB-3083D manufactured by Nitto Denko Corporation) was attached using a dicing frame, and the dicing tape surface was set on an adsorption plate by vacuum suction. Then, at room temperature, the glass wafer was peeled off by lifting one point of the glass with tweezers. If the 30 μm thick wafer could be peeled off without cracking, it was indicated by "○", and if an abnormality such as cracking occurred, it was evaluated as defective and indicated by "×". At that time, it was also confirmed whether the temporary adhesive layer remained as a residue on the substrate (silicon wafer) side or the support (glass wafer) side.

[0142] (5) Washing Removability Test After the peelability test in (4) was completed, the 200 mm diameter wafer mounted on the dicing frame via the dicing tape was set on a spin coater with the peeled surface facing up, and SPIS-TA-CLEANER 25 (manufactured by Shin-Etsu Chemical Co., Ltd.) was sprayed as a cleaning solvent for 5 minutes. After that, the wafer was rotated and rinsed by spraying isopropyl alcohol (IPA). The appearance was then observed and the presence or absence of remaining adhesive was visually checked. Those in which no remaining resin was observed were evaluated as good and indicated by "○", and those in which remaining resin was observed were evaluated as bad and indicated by "×".

[0143] (6) Peel Force Test: A 200 mm diameter silicon wafer (thickness: 725 μm) with 10 μm high, 40 μm diameter copper posts formed on the entire surface was spin-coated with curable silicone resin solutions A1 to A8 and CA1 to CA5, and heated on a hot plate at 100 ° C for 2 minutes to form a silicone resin layer on the wafer bump-forming surface with the film thickness shown in Table 1. The silicone resin layer was then cured under the conditions shown in Table 1 and cooled to room temperature. Five 150 mm long x 25 mm wide polyimide tapes were attached to the silicone resin layer on the wafer, and the temporary adhesive layer was removed from the areas where the tape was not attached. Using an AUTOGRAPH (AG-1) from Shimadzu Corporation, the tape was peeled 120 mm from one end at 180 ° peeling at 25 ° C and a speed of 300 mm / min. The average force applied at that time (120 mm stroke x 5 times) was taken as the initial peel force of the silicone resin layer. In addition, a cured silicone resin layer was prepared on the surface of the wafer where the bumps were formed in the same manner as above, and the tape peeling force after heat treatment in an oven at 250° C. in air for 1 hour was measured as the peeling force after heat resistance.

[0144] (7) Storage Modulus Measurement Curable silicone resin solutions A1 to A8 and CA1 to CA5 were each spin-coated onto a glass wafer and heated on a hot plate at 100°C for 2 minutes to form a silicone resin layer on the glass wafer with the film thickness shown in Table 1. The silicone resin layer was then cured under the conditions shown in Table 1 and cooled to room temperature. The glass wafer containing the resulting silicone resin layer was subjected to elastic modulus measurement at 25°C using an Ares G2 manufactured by TA Instruments, sandwiched between 25 mmφ aluminum plates so that a load of 50 gf was applied to the silicone resin layer, and the obtained elastic modulus value was taken as the storage modulus of the silicone resin layer.

[0145] (8) Thermogravimetric Measurement in Air: An appropriate amount of curable silicone resin solutions A1-A8 and CA1-CA5 was poured into a mold (H) 100 mm x (W) 100 mm x (D) 1 mm with a Teflon (registered trademark) coated surface. The excess resin solution was removed with a scraper, and then heated on a hot plate at 100 ° C for 2 minutes. Each silicone resin layer was then cured under the conditions shown in Table 1 and cooled to room temperature to produce a cured silicone resin layer. Thermogravimetric measurement was performed in air using 10 mg of the resulting cured product, and the 1% weight loss temperature of the cured product was measured. The instrument used here was a TGA2 manufactured by Mettler Toledo, and the measurement was performed under conditions of 40 to 400 ° C (10 ° C / min).

[0146]

[0147] As shown in Table 1, temporary adhesives made from curable silicone resin compositions containing organopolysiloxanes in which only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule is located either on a side chain or at a terminal were confirmed to exhibit sufficient curability, and to have excellent wafer processing durability, peel stability after high-temperature, long-term heat treatment in air, and washability after peeling (Examples 1 to 8). On the other hand, in comparative examples that did not contain organopolysiloxanes in which only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule is located either on a side chain or at a terminal, or that had alkenyl groups or silicon-bonded hydrogen atoms (SiH groups) at both terminals, it was confirmed that high-temperature, long-term heat treatment adversely affected subsequent peelability (Comparative Examples 1 to 5).

[0148] This specification includes the following aspects: [1] A temporary adhesive for wafer processing, for temporarily bonding a wafer to a support, the temporary adhesive for wafer processing being made of a curable silicone resin composition that can be cured by a hydrosilylation reaction, the curable silicone resin composition being characterized in that it contains an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule. [2] The curable silicone resin composition comprises: (A) 100 parts by mass of an organopolysiloxane having two or more alkenyl groups per molecule; (B) 0.1 to 100 parts by mass of an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule; (C) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to a silicon atom (SiH group) per molecule, in an amount such that the sum of the SiH groups in components (B) and (C) relative to the sum of the alkenyl groups in components (A) and (B) is 0.3 to 5, in terms of the molar ratio; (D) 0.1 to 200 parts by mass of a non-functional organopolysiloxane; and (E) a hydrosilylation reaction catalyst in an amount of 0.1 to 5,000 ppm, calculated as the metal atom weight, relative to the total mass of components (A), (B), (C), and (D). [3] The temporary adhesive for wafer processing according to [2], characterized in that the organopolysiloxane of component (A) having two or more alkenyl groups per molecule has at least one aryl group. [4] The temporary adhesive for wafer processing according to [2] or [3], characterized in that the temporary adhesive for wafer processing comprises an organopolysiloxane in which only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule is located either in a side chain or at a terminal. [5] The temporary adhesive for wafer processing according to any one of [2] to [4], characterized in that the curable silicone resin composition is curable by either light or heat, or both.[6] The temporary adhesive for wafer processing according to any one of [1] to [5], characterized in that the non-functional organopolysiloxane (D) is a dimethylpolysiloxane having a viscosity of 100 to 500,000 mPa·s in a 30% by mass toluene solution at 25°C. [7] The temporary adhesive for wafer processing according to any one of [1] to [6], characterized in that the curable silicone resin composition containing components (A) to (E) further contains a hydrosilylation reaction inhibitor as component (F) in an amount of 0.001 to 10 parts by mass, relative to the total mass of components (A), (B), and (C). [8] The temporary adhesive for wafer processing according to any one of [1] to [7], characterized in that after curing of the curable silicone resin composition, a 180° peel strength of a 25 mm wide test piece from a silicon substrate at 25°C is 2 gf or more and 100 gf or less. [9] The temporary adhesive for wafer processing according to any one of [1] to [8], characterized in that after curing of the curable silicone resin composition, the storage modulus at 25° C. is 1,000 Pa or more and 1,000 MPa or less.

[10] A method for producing a thin wafer, comprising the steps of: (a) releasably adhering the circuit-forming surface of a wafer having a circuit-forming surface on one side and a non-circuit-forming surface on a back side to a support using the temporary adhesive for wafer processing according to any one of [1] to [9], thereby forming a wafer laminate; (b) curing the temporary adhesive; (c) grinding or polishing the non-circuit-forming surfaces of the wafers in the wafer laminate; (d) processing the non-circuit-forming surfaces of the wafers; and (e) peeling the processed wafers from the support.

[11] A wafer laminate comprising a support, a temporary adhesive layer obtained from the temporary adhesive for wafer processing according to any one of [1] to [9] laminated thereon, and a wafer having a circuit-forming surface on the front side and a circuit-free surface on the back side, wherein the temporary adhesive layer is peelably adhered to the front side of the wafer.

[0149] The present invention is not limited to the above-described embodiments, which are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

Claims

1. A temporary adhesive for wafer processing, for temporarily bonding a wafer to a support, said temporary adhesive for wafer processing being made of a curable silicone resin composition that can be cured by a hydrosilylation reaction, said curable silicone resin composition being characterized in that it contains an organopolysiloxane having only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) per molecule.

2. The curable silicone resin composition comprises: (A) 100 parts by mass of an organopolysiloxane having two or more alkenyl groups per molecule; (B) 0.1 to 100 parts by mass of an organopolysiloxane having only one alkenyl group or only one silicon-bonded hydrogen atom (SiH group) per molecule; (C) an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms (SiH groups) per molecule, in an amount such that the sum of the SiH groups in components (B) and (C) to the sum of the alkenyl groups in components (A) and (B) is 0.3 to 5, in terms of molar ratio; (D) 0.1 to 200 parts by mass of a non-functional organopolysiloxane; and (E) a hydrosilylation reaction catalyst in an amount of 0.1 to 5,000 ppm, calculated as metal atom weight, based on the total mass of components (A), (B), (C), and (D). The temporary adhesive for wafer processing according to claim 1, comprising:

3. A temporary adhesive for wafer processing according to claim 2, characterized in that the organopolysiloxane having two or more alkenyl groups in one molecule of component (A) has at least one aryl group.

4. The temporary adhesive for wafer processing according to claim 2, characterized in that the non-functional organopolysiloxane of component (D) is a dimethylpolysiloxane having a viscosity of 100 to 500,000 mPa·s at 25°C in a 30% by weight toluene solution.

5. The temporary adhesive for wafer processing according to claim 2, wherein the curable silicone resin composition containing components (A) to (E) further contains a hydrosilylation reaction inhibitor as component (F) in an amount of 0.001 to 10 parts by mass relative to the total mass of components (A), (B), and (C).

6. The temporary adhesive for wafer processing according to claim 1, characterized in that it contains an organopolysiloxane in which only one alkenyl group or only one hydrogen atom bonded to a silicon atom (SiH group) is located in either a side chain or at the end per molecule.

7. The temporary adhesive for wafer processing according to claim 1, wherein the curable silicone resin composition can be cured by either light or heat, or both.

8. The temporary adhesive for wafer processing according to claim 1, characterized in that after the curable silicone resin composition has cured, the 180° peel strength of a 25 mm wide test piece against a silicon substrate at 25°C is 2 gf or more and 100 gf or less.

9. The temporary adhesive for wafer processing according to claim 1, wherein the storage modulus of the curable silicone resin composition at 25°C after curing is 1,000 Pa or more and 1,000 MPa or less.

10. A method for manufacturing a thin wafer, comprising the steps of: (a) releasably adhering the circuit-forming surface of a wafer having a circuit-forming surface on its front side and a non-circuit-forming surface on its back side to a support using a temporary adhesive for wafer processing according to any one of claims 1 to 9, thereby forming a wafer laminate; (b) curing the temporary adhesive; (c) grinding or polishing the non-circuit-forming surfaces of the wafers in the wafer laminate; (d) processing the non-circuit-forming surfaces of the wafers; and (e) peeling the processed wafers from the support.

11. A wafer laminate comprising a support, a temporary adhesive layer obtained from the temporary adhesive for wafer processing according to any one of claims 1 to 9 laminated thereon, and a wafer having a circuit-formed surface on its front side and a circuit-free surface on its back side, wherein the temporary adhesive layer is releasably adhered to the front side of the wafer.

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