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

Abstract

The present invention provides: a temporary adhesive for wafer processing, said temporary adhesive being used for the purpose of provisionally bonding a wafer to a support, while being composed of a photocurable silicone resin composition that contains a non-functional organopolysiloxane; a wafer processed body; and a method for producing a thin wafer, said method using a temporary adhesive for wafer processing.

Description

[Technical field]

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

[0002] Three-dimensional semiconductor packaging is becoming essential to achieve higher density and capacity. Three-dimensional packaging technology is a semiconductor manufacturing technology that thins a single semiconductor chip and stacks it in multiple layers while connecting it with through silicon vias (TSVs). To achieve this, a process is required to thin the substrate on which the semiconductor circuit is formed by grinding the non-circuit-forming surface (also called the "back surface") and to form electrodes including TSVs on the back surface. Conventionally, in the back surface grinding process of silicon substrates, a back surface protection tape is attached to the opposite side to the grinding surface to prevent wafer damage during grinding. However, this tape uses an organic resin film as a support base material, and while it is flexible, it is insufficient in strength and heat resistance, and is not suitable for the TSV formation process or the wiring layer formation process on the back surface.

[0003] Therefore, a system has been proposed that can withstand the processes of back grinding, TSV and back electrode formation by bonding a semiconductor substrate to a support such as silicon or glass via an adhesive layer. What is important here is the adhesive layer used when bonding the substrate to the support. This layer must be able to bond the substrate to the support without gaps, have sufficient durability to withstand subsequent processes, and finally allow the thin wafer to be easily peeled off from the support. Since it is peeled off at the end, this adhesive layer is also referred to as a temporary adhesive layer in this specification.

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

[0005] A technology has been proposed in which a silicone adhesive is used as a temporary adhesive layer, in which a substrate is bonded to a support using a heat-curing silicone adhesive, and when peeling, the substrate is separated from the support by immersing it in a chemical that dissolves or decomposes the silicone resin (Patent Document 3). Therefore, peeling takes a very long time, making it difficult to apply to an actual manufacturing process. In addition, after peeling, it also takes a long time to clean the silicone adhesive that remains on the substrate as a residue, and there is also a problem in terms of cleaning removability. On the other hand, in the bonding process, heat-curing silicone requires heating to about 150°C, and warping of the wafer can be a problem, especially when heating on a hot plate. Therefore, when bonding at a low temperature to suppress wafer warping, there is a problem that it takes a long time to complete curing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-64040 A [Patent Document 2] JP 2006-328104 A [Patent Document 3] U.S. Patent No. 7,541,264 Summary of the Invention [Problem to be solved by the invention]

[0007] 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 can bond a substrate and a support at a relatively low temperature and in a short time, thereby improving workability during bonding and wafer warping, and which has sufficient substrate retention after bonding even when a substrate with a high step is used, has high process suitability for the wafer back grinding process, TSV formation process, and wafer back wiring process, and has excellent wafer thermal process resistance, while being easy to peel in the peeling process and having excellent substrate residue cleanability after peeling, thereby improving the productivity of thin wafers. [Means for solving the problem]

[0008] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors discovered that the above-mentioned problems could be solved by using a photocurable silicone resin composition containing a non-functional organopolysiloxane as a temporary adhesive, and thus completed the present invention.

[0009] Therefore, the present invention provides the following temporary adhesive for wafer processing, wafer laminate, and method for producing a thin wafer. 1. A photocurable silicone resin composition comprising: (A) an organopolysiloxane having two or more alkenyl groups per molecule; (B) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms (SiH groups) per molecule; (C) a non-functional organopolysiloxane; and (D) a photoactivatable hydrosilylation reaction catalyst, the non-functional organopolysiloxane (C) is an organopolysiloxane terminated at both molecular chain terminals with trimethylsiloxy groups or dimethylphenylsiloxy groups, and a 30 mass % toluene solution of the non-functional organopolysiloxane (C) has a viscosity of 1,000 to 500,000 mPa s at 25°C. A temporary adhesive for wafer processing, for temporarily bonding a wafer to a support. 2 The photocurable silicone resin composition containing the non-functional organopolysiloxane further contains a hydrosilylation reaction inhibitor as component (E) in an amount of 0.001 to 10 parts by mass relative to the total mass of components (A), (B), and (C). 1 Temporary adhesive for wafer processing. 3After the photocurable silicone resin composition containing the non-functional organopolysiloxane is 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 500 gf or less. 1 or 2 Temporary adhesive for wafer processing. 4 After curing the photocurable silicone resin composition containing the non-functional organopolysiloxane, the storage modulus at 25°C is 1,000 Pa or more and 1,000 MPa or less. 3 Temporary adhesive for wafer processing. 5 A method for producing a thin wafer using a photocurable silicone resin composition containing the non-functional organopolysiloxane, comprising any one of the following aspects in the step of bonding a wafer and a support via a temporary adhesive layer and curing the adhesive to form a wafer laminate (hereinafter, steps (a) and (b)). Here, steps (c) to (e) are common to all aspects. (Aspect 1) (a1) The above-mentioned 1 to 1 are applied to a circuit-forming surface of a wafer having a circuit-forming surface on the front side and a circuit-free surface on the back side, and / or to a bonding surface of a support to be bonded to the wafer. 4 A step of applying and bonding any one of the temporary adhesive compositions for wafer processing. (b1) photocuring the temporary adhesive of the bonded wafers (Aspect 2) (a2) Above 1~ 4 A step of irradiating any one of the temporary adhesive compositions for wafer processing with light. (b2) applying the temporary adhesive composition for wafer processing irradiated with light in (a2) to a circuit-forming surface of a wafer having a circuit-forming surface on its front side and a circuit-free surface on its back side, and / or to a bonding surface of a support to be bonded to the wafer, and then bonding and curing the composition. (c) grinding or polishing the non-circuit-forming surfaces of the wafers in the wafer stack; (d) processing the non-circuit-forming surface of the wafer; (e) peeling the processed wafer from the support. 6 A support and 1 to 2 laminated thereon 4A wafer laminate comprising a temporary adhesive layer obtained from any one of the temporary adhesives for wafer processing described above, 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. Effect of the Invention

[0010] The temporary adhesive for wafer processing of the present invention uses a photocurable silicone resin composition containing a nonfunctional organopolysiloxane, and can bond substrates at a relatively low temperature and in a short time by light irradiation, which suppresses warping of the wafer during bonding and shortens the bonding time. In addition, even after bonding, not only does the resin not undergo thermal decomposition, but the resin does not flow even at high temperatures of 200°C or higher, and has high heat resistance. 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 a wafer having a step, and this film thickness uniformity makes it possible to easily produce a uniform thin wafer of 50 μm or less. Furthermore, since the use of a nonfunctional organopolysiloxane provides excellent peelability, after the thin wafer is produced, the wafer can be easily peeled off from the support, for example at room temperature, making it possible to easily produce a thin wafer that is prone to cracking. In addition, since the temporary adhesive of the present invention can be selectively bonded to the support, no residue derived from the temporary adhesive remains on the thin wafer after peeling, and it also has excellent subsequent cleaning removability. According to the method for manufacturing a thin wafer of the present invention, a thin wafer having a through electrode structure or a bump connection structure can be easily manufactured. [Brief description of the drawings]

[0011] [Figure 1] 2A to 2C are explanatory diagrams showing steps of a method for manufacturing a thin wafer according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Temporary adhesive for wafer processing] The temporary adhesive for wafer processing of the present invention is made of a photocurable silicone resin composition containing a non-functional organopolysiloxane. In view of its applicability to silicon wafers having steps, a silicone resin composition having good spin-coatability is preferably used as the temporary adhesive for wafer processing.

[0013] Such a photocurable silicone resin composition preferably contains, for example, the following components (A) to (D). (A) an organopolysiloxane having two or more alkenyl groups per molecule: 100 parts by mass, (B) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms (SiH groups) per molecule: an amount such that the sum of the SiH groups in component (B) relative to the sum of the alkenyl groups in component (A) is a molar ratio of 0.3 to 10; (C) non-functional organopolysiloxane: 0.1 to 200 parts by mass, and (D) Photoactivated hydrosilylation catalyst: 0.1 to 5,000 ppm, calculated as the metal atomic weight, based on the total mass of the components (A), (B), and (C).

[0014] [Component (A)] Component (A) is an organopolysiloxane having two or more alkenyl groups in one molecule. Component (A) includes linear or branched diorganopolysiloxanes containing two or more alkenyl groups in one molecule, and SiO 4 / 2 and organopolysiloxanes having a three-dimensional network structure and siloxane units (Q units) represented by units. Among these, diorganopolysiloxanes or organopolysiloxanes having a three-dimensional network structure, in which the alkenyl group content is 0.6 to 9 mol%, are preferred. In the present invention, the alkenyl group content refers to the ratio (mol%) of the number of alkenyl groups to the number of Si atoms in the molecule.

[0015] 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. [ka]

[0016] 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.

[0017] 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 1 and d 2 0≦c1≦10, 2≦c 2 ≦10, 0≦d 1 ≦100 and 0≦d 2 An integer that satisfies ≦100, where a+b+c 1 ≧2. a, b, c 1 , c 2 , d 1 and d 2 is preferably a combination of numbers such that the alkenyl group content is 0.6 to 9 mol %.

[0018] 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 becomes 0.3 to 3.0, and f 3 / (f 1 +f 2 +f 3 ) is a number between 0.01 and 0.6.

[0019] The monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon group is preferably one having 1 to 10 carbon atoms, and examples thereof include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, etc.; cycloalkyl groups such as cyclopentyl group, cyclohexyl group, etc.; aryl groups such as phenyl group, tolyl group, etc. Of these, alkyl groups such as methyl group or phenyl group are preferred.

[0020] 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, acryloylethyl, acryloylmethyl, and methacryloylpropyl; (meth)acryloxyalkyl groups such as acryloxypropyl, acryloxyethyl, acryloxymethyl, methacryloxypropyl, methacryloxyethyl, and methacryloxymethyl; and alkenyl-containing monovalent hydrocarbon groups such as cyclohexenylethyl and vinyloxypropyl. Of these, vinyl groups are preferred from an industrial viewpoint.

[0021] In formula (A-1), a and b are each independently an integer of 0 to 3, but it is preferable that a and b are 1 to 3 because the molecular chain terminals are blocked with alkenyl groups, and the highly reactive molecular chain terminal alkenyl groups allow the reaction to be completed in a short time. From the standpoint of cost, it is industrially preferable that a and b are 1. The properties of the alkenyl-containing diorganopolysiloxane represented by formula (A-1) or (A-2) are preferably oil-like or raw rubber-like.

[0022] The organopolysiloxane represented by formula (A-3) is SiO 4 / 2 In formula (A-3), e is independently an integer of 1 to 3, and is preferably 1 from the viewpoint of cost. 3 / (f 1 +f 2 +f 3) is preferably from 0.02 to 1.5, and more preferably from 0.03 to 1.0. The organopolysiloxane represented by formula (A-3) may be used as a solution dissolved in an organic solvent.

[0023] 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 in the above 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 value measured in terms of polystyrene by gel permeation chromatography using toluene as a solvent.

[0024] The (A) component may be used alone or in combination of two or more. In particular, it is 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).

[0025] [(B) Component] The (B) component is a crosslinking agent, and is an organohydrogenpolysiloxane having at least two, preferably three or more, hydrogen atoms bonded to silicon atoms (SiH groups) in one molecule. The organohydrogenpolysiloxane may be linear, branched, or cyclic. The organohydrogenpolysiloxane may be used alone or in combination of two or more.

[0026] The viscosity of the organohydrogenpolysiloxane of component (B) at 25° C. is preferably from 1 to 5,000 mPa·s, and more preferably from 5 to 500 mPa·s. In the present invention, the viscosity is a value measured at 25° C. using a rotational viscometer.

[0027] The Mn of the organohydrogenpolysiloxane of component (B) is preferably 100 to 100,000, and more preferably 500 to 10,000. Mn within the above range is preferable in terms of workability associated with the viscosity of the composition and processability associated with the storage modulus after curing.

[0028] The (B) component is preferably blended so that the molar ratio (SiH group / alkenyl group) of the total SiH group in the (B) component to the total alkenyl group in the (A) component is in the range of 0.3 to 10, more preferably 1.0 to 8.0. If the molar ratio is 0.3 or more, the crosslink density is not reduced, and the problem of the temporary adhesive layer not curing does not occur. Also, if the molar ratio is 10 or less, the crosslink density is not too high, sufficient adhesion and tack are obtained, and the usable time of the treatment liquid can be extended.

[0029] [(C) component] Component (C) is a non-functional organopolysiloxane. Here, "non-functional" means that the molecule does not contain any reactive groups, such as alkenyl groups, hydrogen atoms, hydroxyl groups, alkoxy groups, halogen atoms, or epoxy groups, bonded directly to silicon atoms or via any group.

[0030] Examples of such non-functional organopolysiloxanes include organopolysiloxanes having a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon group, which is unsubstituted or substituted and has 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 groups; cycloalkyl groups such as cyclohexyl groups; aryl groups such as phenyl, tolyl, xylyl, and naphthyl groups; and aralkyl groups such as benzyl and phenethyl groups. In addition, some or all of the hydrogen atoms of these groups may be substituted with halogen atoms such as chlorine, fluorine, and bromine atoms, and examples of such groups include halogenated alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups. The monovalent hydrocarbon group is preferably an alkyl group or an aryl group, and more preferably a methyl group or a phenyl group.

[0031] There are no particular limitations on the molecular structure of the nonfunctional organopolysiloxane of component (C) and it may be any of linear, branched, cyclic, etc., but linear or branched organopolysiloxanes are preferred, and linear diorganopolysiloxanes in which the main chain is basically composed of repeating diorganosiloxane units and both molecular chain terminals are blocked with triorganosiloxy groups are preferred.

[0032] The viscosity (25°C) of the non-functional organopolysiloxane in a 30% by mass toluene solution is preferably 100 to 500,000 mPa·s, and more preferably 200 to 100,000 mPa·s, from the viewpoints of workability of the composition, applicability to substrates, mechanical properties of the cured product, peelability of the support, etc. If it is in this range, it has an appropriate molecular weight, so it is preferable because it does not volatilize when the silicone resin composition is heat-cured, making it difficult to obtain the desired effect, does not cause wafer cracking in wafer thermal processes such as CVD, and has good workability and applicability.

[0033] Examples of the non-functional organopolysiloxane include dimethylsiloxane polymers capped with trimethylsiloxy groups at both molecular chain terminals, phenylmethylpolysiloxanes capped with trimethylsiloxy groups at both molecular chain terminals, 3,3,3-trifluoropropylmethylsiloxane polymers capped with trimethylsiloxy groups at both molecular chain terminals, dimethylsiloxane-methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals, dimethylsiloxane-3,3,3-trifluoropropylmethyl copolymers capped with trimethylsiloxy groups at both molecular chain terminals, endblocked dimethylsiloxane-3,3,3-trifluoropropylmethylsiloxane-methylphenylsiloxane copolymer, endblocked dimethylsiloxane-3,3,3-trifluoropropylmethylsiloxane-methylphenylsiloxane copolymer, endblocked dimethylpolysiloxane-both molecular ends with dimethylphenylsiloxy groups, endblocked methylphenylpolysiloxane-both molecular ends with dimethylphenylsiloxy groups, endblocked dimethylsiloxane-methylphenylsiloxane copolymer, etc.

[0034] The non-functional organopolysiloxane of component (C) may be used alone or in combination of two or more, and is preferably in the form of an oil or a crude rubber.

[0035] [(D) component] Component (D) is a photoactivatable hydrosilylation catalyst, which is activated by irradiation with light, particularly ultraviolet light with a wavelength of 300 to 400 nm, and promotes the addition reaction between the alkenyl group in component (A) and the Si-H group in component (B). This promotion effect is temperature-dependent, with a higher promotion effect being obtained at higher temperatures. Therefore, after the preferred light irradiation, it is preferred to use the catalyst at an environmental temperature of 0 to 200°C, more preferably 10 to 100°C, in order to complete the reaction within an appropriate reaction time.

[0036] Photoactivatable hydrosilylation catalysts are mainly platinum group metal catalysts or iron group metal catalysts, of which platinum group metal catalysts include platinum, palladium, and rhodium complexes, and iron group metal catalysts include nickel, iron, and cobalt complexes. Of these, platinum group metal complexes are preferred and often used because they are relatively easy to obtain and exhibit good catalytic activity.

[0037] In addition, the ligand is preferably one that exhibits catalytic activity in the mid- to long-wavelength UV light of UV-B to UV-A in order to suppress damage to the wafer. Examples of such ligands include cyclic diene ligands and β-diketonato ligands.

[0038] From the above, preferred examples of the photoactivatable hydrosilylation reaction catalyst include, for example, a cyclic diene ligand type, 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. Also β-diketonato ligand type Examples of the platinum complex include β-diketonatoplatinum(II) and 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).

[0039] When using these catalysts, if they are solid catalysts they can be used in solid form; however, in order to obtain a more uniform cured product it is preferable to use a solution thereof in a suitable solvent and then dissolve it in the alkenyl-containing organopolysiloxane of component (A). Examples of the solvent include isononane, toluene, and 2-(2-butoxyethoxy)ethyl acetate.

[0040] The amount of the (D) component to be added may be any effective amount, but is usually 0.1 to 5,000 ppm, preferably 0.5 to 2,000 ppm, more preferably 1 to 500 ppm, of platinum (calculated as metal atomic weight) relative to the total mass of (A), (B), and (C). If it is 0.1 ppm or more, the curability of the composition is not reduced, the crosslink density is not lowered, and the holding power is not reduced. If it is 0.5% or less, the usable time of the treatment bath can be extended.

[0041] [(E) component] The photocurable silicone resin composition may further contain a reaction inhibitor as component (E), which is optionally added as necessary to prevent the composition from thickening or gelling when the composition is prepared or applied to a substrate.

[0042] 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. Among these, 1-ethynylcyclohexanol and 3-methyl-1-butyn-3-ol are preferred.

[0043] When the photocurable silicone resin composition contains the component (E), the content should be adjusted to an optimal amount since the control ability differs depending on the chemical structure, but in consideration of the effect on curability, storage stability, and physical properties after curing, the content is preferably 0.001 to 10 parts by mass, and more preferably 0.01 to 10 parts by mass, based on the total mass of the components (A), (B), and (C). If the content of the component (E) is within the above range, the usable time of the composition is long, long-term storage stability is obtained, and curability and workability are good.

[0044] The photocurable silicone resin composition further comprises R A 3SiO 0.5 Units (wherein R A are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms.) and a SiO2 unit, and R A 3SiO 0.5 Unit of mole ratio (R A 3SiO 0.5 An organopolysiloxane having a SiO2 ratio (SiO2 / SiO2) of 0.3 to 1.8 may be added. The amount added is preferably 0 to 500 parts by mass, and more preferably more than 0 to 300 parts by mass, per 100 parts by mass of component (A).

[0045] In order to further enhance the heat resistance of the temporary adhesive layer obtained from the photocurable silicone resin composition, a filler such as silica may be added within a range that does not impair the performance of the composition.

[0046] The photocurable silicone resin composition may be used in the form of a solution by adding a solvent for the purpose 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 above-mentioned components, but hydrocarbon solvents such as pentane, hexane, cyclohexane, isooctane, nonane, decane, p-menthane, pinene, isododecane, and limonene are preferred.

[0047] The method of dissolving the composition includes a method of preparing the photocurable silicone resin composition, and then adding a solvent to adjust the viscosity to a desired level, or a method of diluting the high-viscosity components (A), (B) and / or (C) with a solvent in advance to improve workability and mixability, and then mixing the remaining components. In addition, the mixing method for dissolving the composition may be selected appropriately from a shaking mixer, a magnetic stirrer, various mixers, etc., based on the viscosity of the composition and workability.

[0048] The amount of the solvent to be added may be appropriately set from the viewpoints of adjusting the viscosity and workability of the composition, the film thickness of the temporary adhesive layer, and the like; for example, it is preferably 5 to 900 parts by mass, and more preferably 10 to 400 parts by mass, per 100 parts by mass of the photocurable silicone resin composition.

[0049] The temporary adhesive layer can be formed by applying the photocurable 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 photocurable silicone resin composition in the form of a solution.

[0050] From the viewpoint of coatability, the viscosity of the solution of the photocurable silicone resin composition at 25° C. is preferably from 1 to 100,000 mPa·s, and more preferably from 10 to 10,000 mPa·s.

[0051] The photocurable silicone resin composition has a 180° peel strength of typically 2 to 50 gf, preferably 3 to 30 gf, and more preferably 5 to 20 gf, of a 25 mm wide test piece (e.g., a silicon substrate test piece) after curing at 25° C. If it is 2 gf or more, there is no risk of the wafer being displaced during wafer grinding, and if it is 50 gf or less, the wafer can be easily peeled off.

[0052] The photocurable silicone resin composition has a storage modulus at 25° C. after curing of 1,000 Pa to 1,000 MPa, preferably 10,000 Pa to 500 MPa. If the storage modulus is 1,000 Pa or more, the film formed is strong and there is no risk of wafer misalignment and associated wafer cracking during wafer grinding, while if it is 1,000 MPa or less, deformation stress during wafer thermal processing such as CVD can be alleviated and the film is stable during wafer thermal processing.

[0053] [Method of manufacturing thin wafers] The method for producing a thin wafer of the present invention is characterized by using a temporary adhesive layer made of a photocurable silicone resin composition as an adhesive layer between a wafer having a semiconductor circuit or the like and a support, and two embodiments and their illustrations are shown in Figure 1. In either embodiment, the thickness of the thin wafer obtained by the production method of the present invention is typically 5 to 300 μm, more typically 10 to 100 μm.

[0054] A first aspect of the method for producing a thin wafer of the present invention comprises the following steps (a1) to (e) and, as necessary, steps (f) to (i). [Process (a1)] Step (a1) is a temporary bonding step in which 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 is releasably bonded to a support using the temporary adhesive for wafer processing to form a wafer laminate.

[0055] 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.

[0056] The wafer applicable to the present invention is usually a semiconductor wafer. 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.

[0057] In the first embodiment of the present invention, the photocurable silicone resin composition is irradiated with light through a support, and therefore the support can be a light-transmitting substrate such as a glass plate, a quartz plate, an acrylic plate, a polycarbonate plate, a polyethylene terephthalate plate, etc. Among these, a glass plate is preferred because it is transparent to ultraviolet light and has excellent heat resistance.

[0058] The temporary adhesive layer may be formed by laminating the photocurable silicone resin composition molded into a film on a wafer or a support, or by applying the photocurable silicone resin composition by a method such as spin coating or roll coating. When the photocurable silicone resin composition is a solution containing a solvent, after application, the composition is prebaked in advance at a temperature of preferably 20 to 200° C., more preferably 30 to 150° C., depending on the volatilization conditions of the solvent, before use.

[0059] The temporary adhesive layer is preferably formed and used with a thickness of 0.1 to 500 μm, preferably 1.0 to 200 μm. If the thickness is 0.1 μm or more, the adhesive layer can be applied to the entire substrate without leaving any uncoated areas. On the other hand, if the thickness is 500 μm or less, the adhesive layer can withstand the grinding process when forming a thin wafer.

[0060] The method for bonding the support and the surface of the wafer via the temporary adhesive layer includes a method of uniformly pressing them together under reduced pressure, preferably in a temperature range of 0 to 200°C, more preferably 20 to 100°C.

[0061] The pressure when the wafer on which the temporary adhesive layer is formed and the support is pressure-bonded depends on the viscosity of the temporary adhesive layer, but is preferably 0.01 to 10 MPa, more preferably 0.05 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 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 the flatness of the wafer and the temporary adhesive layer being deteriorated, and the subsequent wafer processing is good.

[0062] Wafer bonding can be performed using a commercially available wafer bonder, such as EVG520IS, 850TB from EVG, or XBS300 from SUSS MicroTec.

[0063] [Process (b1)] Step (b1) is a step of photocuring the temporary adhesive layer. After the wafer processed body (laminate substrate) is formed, the temporary adhesive layer is photocured by irradiating light from the light-transmitting support side. The type of active light irradiated is not particularly limited, but ultraviolet light is preferable, and ultraviolet light having a wavelength of 300-400 nm is more preferable. The ultraviolet irradiance (illuminance) is 100 mJ / cm2 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 curing properties, it is desirable that the ultraviolet ray irradiation amount (illuminance) is within the above range or more, 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 ultraviolet ray irradiation amount (illuminance) is below the above range, sufficient energy is irradiated to 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.

[0064] The ultraviolet irradiation may be light having a plurality of emission spectra or light having a single emission spectrum. The single emission spectrum may be a broad spectrum in the region of 300 nm to 400 nm. The 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.

[0065] 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 lasers; liquid lasers of organic dye solutions; and solid-state lasers in which rare earth ions are contained in inorganic single crystals.

[0066] 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 having optical transparency for wavelengths shorter than 300 nm, such as a quartz wafer, is used as the support, it is preferable to remove light having a wavelength in the wavelength region shorter than 300 nm by an optical filter in order to obtain a sufficient cured product. As a result, the irradiance of each wavelength in the wavelength region shorter than 300 nm is set 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. In addition, when there are multiple peaks in the wavelength region from 300 nm to 400 nm in the emission spectrum, the peak wavelength showing the maximum absorbance among them is set to the maximum peak wavelength. There is no particular limitation on the optical filter, and a known one may be used as long as it cuts wavelengths shorter than 300 nm. 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.).

[0067] 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.

[0068] When the photocurable silicone resin composition of the present invention is cured, the light irradiation time depends on the illuminance and cannot be generally specified, but if the illuminance is adjusted to, for example, 1 to 300 seconds, preferably 10 to 200 seconds, more preferably 30 to 150 seconds, the irradiation time is appropriately short and does not cause any particular problem in the work process. In addition, the photocurable silicone resin composition that has been irradiated with light gels 1 to 120 minutes, particularly 5 to 60 minutes after irradiation. In addition, in the present invention, gelation means a state in which the curing reaction of the photocurable silicone resin composition has partially progressed and the composition has lost fluidity.

[0069] [Process (c)] Step (c) is a step of grinding or polishing the non-circuit surface of the wafer temporarily bonded to the support, that is, a step of grinding the back side of the wafer of the wafer laminate obtained in the above step to reduce the thickness of the wafer. There is no particular limitation on the method of grinding the back side of the wafer, and a known grinding method is adopted. Grinding is preferably performed while cooling the wafer and grindstone (diamond, etc.) by spraying water on them. An example of an apparatus for grinding the back side of the wafer is DAG-810 (product name) manufactured by Disco Corporation. In addition, the back side of the wafer may be subjected to chemical mechanical polishing (CMP).

[0070] [Step (d)] Step (d) is a step of processing the non-circuit-forming surface of the wafer laminate obtained by grinding the non-circuit-forming surface in step (c). That is, it is a step of processing the non-circuit-forming surface of the wafer of the wafer laminate thinned by back grinding. This step includes various processes used at the wafer level. Examples include electrode formation, metal wiring formation, protective film formation, and the like. More specifically, conventionally known processes include metal sputtering for forming electrodes, etc., wet etching for etching the metal sputtering layer, application of a resist to serve as a mask for forming metal wiring, exposure, and development to form a pattern, resist peeling, dry etching, formation of metal plating, silicon etching for forming TSV, and formation of an oxide film on the silicon surface.

[0071] [Step (e)] Step (e) is a step of peeling the wafer processed in step (d) from the support, that is, a step of peeling the wafer from the support before dicing after various processing is performed on the thinned wafer. This peeling step is generally performed under relatively mild conditions of room temperature to about 60°C. Examples of peeling methods include a method of fixing one of the wafer or the support of the wafer laminate horizontally and lifting the other at a certain angle from the horizontal direction, a method of immersing the wafer laminate in a solvent in advance to swell the temporary adhesive layer, and then subjecting it to peel peeling as described above, a method of attaching a protective film to the ground surface of the ground wafer, and peeling the wafer and the protective film from the wafer laminate by a peel method, etc. When the peeling step is performed by these peeling methods, it is usually performed at room temperature.

[0072] Also, step (e) is (e1) applying a dicing tape to the wafer surface of the processed wafer; (e2) vacuum-adsorbing the dicing tape surface onto the adsorption surface; and (e3) A step of peeling off the support from the processed wafer by peeling off while the temperature of the adsorption surface is in the range of 10 to 100°C. In this way, the support can be easily peeled off from the processed wafer, and the subsequent dicing step can be easily performed.

[0073] In addition, after step (e), (f) A step of removing the temporary adhesive layer remaining on the circuit-formed surface of the peeled wafer. It is preferable to carry out the step (e). A part of the temporary adhesive layer may remain on the circuit-forming surface of the wafer peeled off from the support in the step (e), and the temporary adhesive layer can be removed, for example, by washing the wafer.

[0074] In this step (f), any cleaning liquid that dissolves the silicone resin of the temporary adhesive layer can be used, 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.

[0075] In addition, when the temporary adhesive layer is difficult to remove, a base or an acid may be added to the cleaning solution. As the base, amines such as ethanolamine, diethanolamine, triethanolamine, triethylamine, and ammonia; and ammonium salts such as tetramethylammonium hydroxide may be used. As the acid, organic acids such as acetic acid, oxalic acid, benzenesulfonic acid, and dodecylbenzenesulfonic acid may be used. 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 mass%, more preferably 0.1 to 5 mass%. In addition, in order to improve the removability of the remaining matter, an existing surfactant may be added. In addition, the SPIS-TA-CLEANER series (manufactured by Shin-Etsu Chemical Co., Ltd.), which is available as a wafer cleaning agent, may also be suitably used.

[0076] The method for cleaning the wafer includes 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., and if necessary, after dissolving the temporary adhesive layer with these cleaning liquids, it is possible to finally rinse with water or alcohol and perform a drying treatment.

[0077] As a second embodiment of the method for producing a thin wafer of the present invention, the following steps (a2) and (b2) are shown. The steps after (b2), that is, steps (c) to (e), preferably steps (c) to (f), are the same as those of the first embodiment described above.

[0078] [Process (a2)] Step (a2) is a step of forming a layer of a photocurable silicone resin composition that has been irradiated with light on a wafer and / or a support.

[0079] Unlike the first embodiment in which the wafer and the support are bonded and then irradiated with light, the photocurable silicone resin composition is irradiated with light before bonding, making it unnecessary to perform a light irradiation process through the support, and as a result, the support does not need to be light-transmitting. Therefore, according to this embodiment, in addition to the application examples of the support, substrates that do not transmit light, such as silicon, aluminum, SUS, copper, germanium, gallium-arsenide, gallium-phosphorus, and gallium-arsenide-aluminum, can also be applied as the support. In addition, according to this method, the influence of curing inhibition from the wafer can be reduced, so that the application range of the wafer can be expanded.

[0080] Regarding the application of the photocurable silicone resin composition that has been irradiated with light, it can be applied to either (1) the wafer, (2) the support, or (3) both the wafer and the support.

[0081] Examples of the method of irradiating the photocurable silicone resin composition with light before bonding include a method of applying the composition on a wafer and / or a support while irradiating the composition with light, a method of applying the composition on the entirety of the composition and then applying it on a wafer and / or a support, and a method of applying the composition on a wafer and / or a support and then irradiating the composition with light, but there is no particular limitation and the method may be appropriately selected in consideration of workability. In addition, the actinic ray species, ultraviolet ray irradiation amount (illuminance), light source, emission spectrum, light irradiation device, and light irradiation time in the light irradiation can be the methods listed in [Step (b1)] of the first embodiment.

[0082] The first and second temporary adhesive layers can be formed in the same manner as in the first embodiment, and each of them can be formed as a film, or a corresponding composition or a solution thereof on a wafer and / or a support by a method such as spin coating, roll coating, etc. When used as a solution, after spin coating, it is prebaked in advance at a temperature of 20 to 200°C, preferably 30 to 150°C, depending on the volatilization conditions of the solvent, and then used.

[0083] [Process (b2)] Step (b2) is a step of bonding under vacuum the wafer with the circuit formed thereon and / or the support formed with the photocurable silicone resin composition layer produced in step (a2). At this time, the substrate is uniformly pressure-bonded under reduced pressure (vacuum) at a temperature preferably in the range of 0 to 200°C, more preferably 20 to 100°C, to form a wafer processed body (laminate substrate) in which the wafer is bonded to the support. Here, the same wafer bonding apparatus as that in the first embodiment can be used as the wafer bonding apparatus. EXAMPLES

[0084] The present invention will be described 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 is measured at 25°C using a TVB-10M rotational viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0085] [1] Preparation of photocurable silicone resin solution [Preparation Example 1] A solution of 100 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups in the molecular side chains and Mn of 30,000 and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2A solution consisting of 50 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 and 2 mol% of units (Vi units) and 100 parts by mass of toluene, 230 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 and represented by the following formula (M-1), 50 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a viscosity (25°C) of 30,000 mPa·s of a 30% by mass toluene solution, and 120 parts by mass of toluene, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.4 parts by mass of a toluene solution (platinum concentration 1.0% by mass) of a photoactivatable hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum(IV) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare a photocurable silicone resin solution A1. The viscosity of resin solution A1 at 25°C was 230 mPa·s. [ka]

[0086] [Preparation Example 2] A solution of 70 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups in the molecular side chains and Mn of 30,000, 30 parts by mass of dimethylpolysiloxane having 0.15 mol % vinyl groups in both terminal chains and Mn of 60,000, and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2A solution consisting of 50 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 and 2 mol% of units (Vi units) and 100 parts by mass of toluene, 180 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 represented by formula (M-1), 30 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a 30% by mass toluene solution viscosity (25°C) of 1,000 mPa·s, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.4 parts by mass of a toluene solution (platinum concentration 1.0% by mass) of a photoactivatable hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum(IV) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare photocurable silicone resin solution A2. The viscosity of resin solution A2 at 25°C was 100 mPa·s.

[0087] [Preparation Example 3] A solution of 100 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups at both ends and at the side chains and Mn of 30,000 and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2 A solution consisting of 50 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 consisting of 2 mol% of units (Vi units) and 100 parts by mass of toluene, 230 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 represented by formula (M-1), 20 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a viscosity (25 °C) of 100,000 mPa·s of a 30% by mass toluene solution, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.4 parts by mass of a toluene solution (platinum concentration 1.0% by mass) of a photoactivatable hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum (IV) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare photocurable silicone resin solution A3. The viscosity of resin solution A3 at 25°C was 330 mPa·s.

[0088] [Preparation Example 4] A solution of 100 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups at both ends and at the side chains and Mn of 30,000 and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2 A solution consisting of 200 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 consisting of 2 mol% of units (Vi units) and 400 parts by mass of toluene, 430 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 represented by formula (M-1), 100 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a viscosity (25°C) of 30,000 mPa·s of a 30% by mass toluene solution, and 120 parts by mass of toluene, and 1.2 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.8 parts by mass of a toluene solution (platinum concentration 1.0% by mass) of a photoactivatable hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum (IV) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare photocurable silicone resin solution A4. The viscosity of resin solution A4 at 25°C was 120 mPa·s.

[0089] [Preparation Example 5] A solution of 70 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups in the molecular side chains and Mn of 30,000, 30 parts by mass of dimethylpolysiloxane having 0.15 mol % vinyl groups in both terminal chains and Mn of 60,000, and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2A solution consisting of 200 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 and 400 parts by mass of toluene, 380 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 represented by formula (M-1), 150 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a 30% by mass toluene solution viscosity (25°C) of 1,000 mPa·s, and 1.2 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.8 parts by mass of a toluene solution (platinum concentration 1.0% by mass) of a photoactivatable hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum(IV) was added thereto, and the mixture was filtered through a 0.2μm membrane filter to prepare photocurable silicone resin solution A5. The viscosity of resin solution A5 at 25°C was 80 mPa·s.

[0090] [Preparation Example 6] A solution of 100 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups at both ends and at the side chains and Mn of 30,000 and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2 A solution consisting of 50 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 consisting of 2 mol% of units (Vi units) and 100 parts by mass of toluene, 230 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 represented by formula (M-1), 50 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a viscosity (25°C) of 30,000 mPa·s in a 30% by mass toluene solution, and 0.6 parts by mass of 1-ethynylcyclohexanol were added and mixed. Furthermore, 0.8 parts by mass of a photoactivatable hydrosilylation reaction catalyst; bis(2,4-heptanedionato)platinum(II) acetate 2-(2-butoxyethoxy)ethyl solution (platinum concentration 0.5% by mass) was added thereto, and the mixture was filtered through a 0.2 μm membrane filter to prepare photocurable silicone resin solution A6. The viscosity of resin solution A6 at 25°C was 230 mPa·s.

[0091] [Preparation Example 7] A solution of 70 parts by mass of dimethylpolysiloxane having 2.5 mol % vinyl groups in the molecular side chains and Mn of 30,000, 30 parts by mass of dimethylpolysiloxane having 0.15 mol % vinyl groups in both terminal chains and Mn of 60,000, and 200 parts by mass of toluene was added with SiO 4 / 2 Units (Q units) 50 mol%, (CH3)3SiO 1 / 2 Units (M units) 48 mol% and (CH2=CH)3SiO 1 / 2 A solution consisting of 200 parts by mass of vinylmethylpolysiloxane with Mn of 7,000 and 400 parts by mass of toluene, 380 parts by mass of organohydrogenpolysiloxane with Mn of 2,800 and represented by formula (M-1), 150 parts by mass of dimethylpolysiloxane with trimethylsiloxy groups blocked at both ends of the molecular chain and a viscosity (25°C) of 1,000 mPa·s in a 30% by mass toluene solution, and 1.2 parts by mass of 1-ethynylcyclohexanol were added and mixed. Further, 1.6 parts by mass of a photoactivatable hydrosilylation reaction catalyst; bis(2,4-heptanedionato)platinum(II) acetate 2-(2-butoxyethoxy)ethyl solution (platinum concentration 0.5% by mass) was added thereto, and filtered with a 0.2μm membrane filter to prepare photocurable silicone resin solution A7. The viscosity of resin solution A7 at 25°C was 80 mPa·s.

[0092] [Comparative Preparation Example 1] A thermosetting silicone resin solution CA1 was prepared in the same manner as in Preparation Example 1, except that 0.4 parts by mass of a photoactivated hydrosilylation reaction catalyst; (methylcyclopentadienyl)trimethylplatinum(IV) toluene solution (platinum concentration 1.0% by mass) was replaced with 0.4 parts by mass of a thermally activated hydrosilylation reaction catalyst; CAT-PL-5 (Shin-Etsu Chemical Co., Ltd., platinum concentration 1.0% by mass). The viscosity of resin solution CA1 at 25°C was 230 mPa s.

[0093] [Comparative Preparation Example 2] Photocurable silicone resin solution CA2 was prepared in the same manner as in Preparation Example 1, except that the solution consisting of 50 parts by mass of dimethylpolysiloxane capped at both molecular chain terminals with trimethylsiloxy groups and 120 parts by mass of toluene was not added. The viscosity of resin solution CA2 at 25°C was 150 mPa s.

[0094] [Comparative Preparation Example 3] Photocurable silicone resin solution CA3 was prepared in the same manner as in Preparation Example 2, except that 30 parts by mass of the dimethylpolysiloxane capped at both molecular chain terminals with trimethylsiloxy groups was not added. The viscosity of resin solution CA3 at 25°C was 180 mPa s.

[0095] [Comparative Preparation Example 4] A photocurable silicone resin solution CA4 was obtained in the same manner as in Preparation Example 1, except that 50 parts by mass of the dimethylpolysiloxane capped with trimethylsiloxy groups at both molecular chain terminals was replaced with 50 parts by mass of a polysiloxane containing epoxy groups in the side chain, as represented by the following formula (M-2) (viscosity of a 30% by mass solution in toluene (25°C): 33,000 mPa s). The viscosity of resin solution CA4 at 25°C was 260 mPa s. [ka]

[0096] [Comparative Preparation Example 5] Photocurable silicone resin solution CA5 was obtained in the same manner as in Preparation Example 2, except that 30 parts by mass of the dimethylpolysiloxane capped with trimethylsiloxy groups at both molecular chain terminals was changed to 30 parts by mass of a polysiloxane containing trimethoxysilyl groups in the side chain, represented by the following formula (M-3) (viscosity of 30% by mass solution in toluene (25°C): 2,500 mPa s). The viscosity of resin solution CA5 at 25°C was 190 mPa s. [ka]

[0097] [2] Fabrication and evaluation of wafer stacks [Examples 1 to 7 and Comparative Examples 1 to 5] Curable silicone resin solutions A1 to A7 and CA1 to CA5 were spin-coated on a 200 mm diameter silicon wafer (thickness: 725 μm) with copper posts of 10 μm height and 40 μm diameter formed all over the surface, and heated on a hot plate at 100° C. for 2 minutes to form a temporary adhesive layer on the wafer bump-formed surface with a thickness shown in Table 1 below. Using a glass plate of 200 mm diameter (thickness: 500 μm) as a support, the silicon wafer with the temporary adhesive layer and the glass plate were each bonded to each other using a wafer bonding device EVG520IS made by EVG at 25° C. for 10 minutes so that the temporary adhesive layer and the glass plate were bonded to each other. -3 Vacuum lamination was performed at a load of 5 kN or less at a pressure of 5 mbar. Thereafter, the curable silicone resin composition layer was irradiated with light using a surface irradiation type UV-LED (wavelength 365 nm) irradiator under the conditions shown in Table 1 to produce a wafer laminate. In addition, in the sample using the thermosetting silicone resin solution CA1, heating was performed on a hot plate under the conditions shown in Table 1 to produce a wafer laminate.

[0098] The following tests were then carried out on the obtained wafer laminate. The results are shown in Table 1. The tests were carried out by the following methods.

[0099] (1) Wafer warpage test In the preparation of the wafer laminate, the warpage of the wafer when the temporary adhesive layer was cured was confirmed by visual observation. The case where there was no warpage was evaluated as "○", and the case where there was warpage was evaluated as "×".

[0100] (2) Adhesion test The wafer laminate was heated in an oven at 180°C for 1 hour and then cooled to room temperature. The adhesion condition at the wafer interface was then visually inspected. If no abnormalities such as air bubbles were observed at the interface, the adhesion condition was evaluated as good and indicated by an "O". If abnormalities were observed, the adhesion condition was evaluated as poor and indicated by an "X".

[0101] (3) Back grinding resistance test The wafer stack was used to grind the backside of the silicon wafer using a diamond grinding wheel in a grinder (DAG-810, manufactured by Disco Corporation). After grinding until the thickness of the substrate was 50 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 "×".

[0102] (4) CVD resistance test (3) After completing the back grinding resistance test, the wafer stack was introduced into a CVD device, and a 2μm SiO2 film deposition experiment was conducted, during which the presence or absence of appearance abnormalities was checked by visual observation. If no appearance abnormalities occurred, the result was evaluated as good and indicated with a "○", and if any appearance abnormalities such as voids, wafer bulges, or wafer breakage occurred, the result was evaluated as bad and indicated with a "×". The conditions for the CVD resistance test were as follows: Equipment name: Samco Corporation Plasma CVD, PD270STL RF500W, internal pressure 40Pa TEOS (Tetraethylorthosilicate): O2 = 20sccm: 680sccm

[0103] (5) Peelability test The peelability of the substrate was evaluated by first attaching a dicing tape (ELP UB-3083D, manufactured by Nitto Denko Corporation) to the wafer side of the wafer stack that had completed the (4) CVD resistance test using a dicing frame, and then setting the dicing tape surface on an adsorption plate by vacuum adsorption. Thereafter, at room temperature, the glass substrate was peeled off by lifting up one point on the glass with tweezers. The case where the 50 μm-thick wafer could be peeled off without cracking was indicated by "○", and the case where cracks or other abnormalities occurred was evaluated as defective and indicated by "×".

[0104] (6) Washability test (5) After the peelability test, the 200 mm diameter wafer (exposed to the CVD resistance test conditions) attached to the dicing frame via the dicing tape was set on a spin coater with the peeled surface facing up, and after spraying SPIS-TA-CLEANER 25 (Shin-Etsu Chemical Co., Ltd.) as a cleaning solvent for 5 minutes, 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 with a circle, and those in which remaining resin was observed were evaluated as bad and indicated with an x.

[0105] (7) Peel strength test Silicone resin solutions A1 to A7 and CA1 to CA5 were each spin-coated onto a silicon wafer (thickness: 725 μm) with a diameter of 200 mm, and heated on a hot plate at 100° C. for 2 minutes to form a silicone resin layer with a thickness shown in Table 1. Thereafter, the curable silicone resin composition layer was irradiated with light under the conditions shown in Table 1 using a surface irradiation type UV-LED (wavelength 365 nm) irradiator to cure the temporary adhesive layer. In addition, in the sample using the thermosetting silicone resin solution CA1, heating was performed on a hot plate under the conditions shown in Table 1 to cure the temporary adhesive layer. Then, five strips of polyimide tape, each 150 mm long and 25 mm wide, were attached to the silicone resin layer on the wafer, and the temporary adhesive layer was removed from the areas where no tape was attached. Using an AUTOGRAPH (AG-1) manufactured by Shimadzu Corporation, the tape was peeled off at 180° from one end at a speed of 300 mm / min at 25°C, for 120 mm, and the average force applied at this time (120 mm stroke x 5 times) was determined as the peel force of the silicone resin layer.

[0106] (8) Storage modulus measurement Curable silicone resin solutions A1 to A7 and CA1 to CA5 were each spin-coated on a silicon substrate, and heated on a hot plate at 100°C for 2 minutes to form a silicone resin layer on the silicon substrate with a thickness shown in Table 1. Thereafter, the curable silicone resin composition layer was irradiated with light under the conditions shown in Table 1 using a surface-irradiation type UV-LED (wavelength 365 nm) irradiator to cure the temporary adhesive layer. Meanwhile, in the sample using the thermosetting silicone resin solution CA1, heating was performed on a hot plate under the conditions shown in Table 1 to cure the temporary adhesive layer. The silicon substrate containing the obtained temporary adhesive layer was subjected to elastic modulus measurement at 25°C and 1 Hz using an Ares G2 manufactured by TA Instruments, while being sandwiched between 25 mm aluminum plates so that a load of 50 gf was applied to the temporary adhesive layer, and the obtained elastic modulus value was regarded as the storage elastic modulus of the silicone resin layer.

[0107] [Table 1]

[0108] [Table 2]

[0109] As shown in Table 1, the wafer laminates of Examples 1 to 7 including the temporary adhesive layer of the present invention can be cured at a relatively low temperature and in a short time, and accordingly, the warping of the wafer during curing is reduced. It was also confirmed that the wafer laminates have sufficient processing durability, excellent peelability, and good cleaning removability after peeling. On the other hand, as shown in Table 2, in Comparative Examples 1 and 2 using a thermally activated catalyst, insufficient curing due to insufficient heating and wafer warping during curing were confirmed. In Comparative Examples 3 and 4 not including non-functional organopolysiloxane and Comparative Examples 5 and 6 including functional organopolysiloxane, the circuit-equipped wafer and the support were strongly adhered to each other, and as a result, the wafer cracked during the peeling process and peeling was not possible.

[0110] [Example 8] The photocurable silicone resin solution A1 was irradiated with light under the conditions shown in Table 2 using a surface irradiation type UV-LED (wavelength 365 nm) irradiator, and then spin-coated on a 200 mm diameter silicon wafer (Si wafer with circuit, thickness: 725 μm) on which copper posts with a height of 10 μm and a diameter of 40 μm were formed all over the surface, and heated on a hot plate at 100° C. for 2 minutes to form a temporary adhesive layer on the wafer bump formation surface with a thickness shown in Table 2 below. Using a 200 mm diameter silicon wafer (Si wafer, thickness: 770 μm) as a support, the Si wafer with circuit having a temporary adhesive layer and the Si wafer as a support were each bonded to each other using an EVG wafer bonding device EVG520IS from EVG at 25° C. and 10° C. -3 The wafers were bonded in vacuum at a pressure of 5 mbar or less and a load of 5 kN to produce a wafer laminate.

[0111] [Example 9] A wafer laminate was produced in the same manner as in Example 8, except that the target onto which the light-irradiated photocurable silicone resin solution A1 was applied was changed from the Si wafer with circuits to the Si wafer serving as a support.

[0112] [Example 10] A wafer laminate was produced in the same manner as in Example 8, except that the target to which the light-irradiated photocurable silicone resin solution A1 was applied was changed from the Si wafer with circuits to both the Si wafer with circuits and the Si wafer as a support.

[0113] [Example 11] A wafer laminate was produced in the same manner as in Example 8, except that the photocurable silicone resin solution used was changed from A1 to A6.

[0114] [Example 12] A wafer laminate was produced in the same manner as in Example 9, except that the photocurable silicone resin solution used was changed from A1 to A6.

[0115] [Example 13] A wafer laminate was produced in the same manner as in Example 10, except that the photocurable silicone resin solution used was changed from A1 to A6.

[0116] The wafer laminates obtained in Examples 8 to 13 were subjected to the same tests as the (1) wafer warpage test to (6) washability test. The results are shown in Table 3. For (7) peel strength test and (8) storage modulus measurement, a photocurable silicone resin solution that had been irradiated with light in advance was spin-coated onto a silicon wafer (Si wafer, thickness: 770 μm) with a diameter of 200 mm, and the silicone resin layer was cured by heating on a hot plate at 100° C. for 5 minutes to prepare a test sample. Thereafter, a peel strength test and a storage modulus measurement test were conducted in the same manner as above, and the results are shown in Table 3.

[0117] [Table 3]

[0118] As shown in Table 3, it was confirmed that in the thin wafer manufacturing method of the present invention, even when a silicone resin solution that has been irradiated with light in advance is applied and then bonded, the same wafer processability can be obtained as when light irradiation is performed after application and bonding. In this case, since light irradiation through a support is not required, the range of application of the support is expanded, and optical damage to the device wafer can be avoided.

Claims

1. A photocurable silicone resin composition comprising (A) an organopolysiloxane having two or more alkenyl groups per molecule, (B) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicon atoms (SiH groups) per molecule, (C) a nonfunctional organopolysiloxane, and (D) a photoactivatable hydrosilylation reaction catalyst, wherein the nonfunctional organopolysiloxane (C) is an organopolysiloxane terminated at both molecular chain terminals with trimethylsiloxy groups or dimethylphenylsiloxy groups, and the viscosity of a 30 mass % toluene solution of the nonfunctional organopolysiloxane (C) at 25°C is 1,000 to 500,000 mPa·s.

2. The temporary adhesive for wafer processing according to claim 1, wherein the photocurable silicone resin composition containing the non-functional organopolysiloxane further contains a hydrosilylation reaction inhibitor as component (E) in an amount of 0.001 to 10 parts by mass relative to the total mass of components (A), (B), and (C).

3. 3. The temporary adhesive for wafer processing according to claim 1 or 2, wherein after curing of the photocurable silicone resin composition containing the non-functional organopolysiloxane, a 180° peel strength of a 25 mm wide test piece against a silicon substrate at 25° C. is 2 gf or more and 500 gf or less.

4. 4. The temporary adhesive for wafer processing according to claim 1, wherein the photocurable silicone resin composition containing the non-functional organopolysiloxane has a storage modulus at 25° C. of 1,000 Pa or more and 1,000 MPa or less after curing.

5. A method for producing a thin wafer using a photocurable silicone resin composition containing a non-functional organopolysiloxane, comprising any one of the following aspects in a step of bonding a wafer and a support via a temporary adhesive layer and curing the adhesive to form a wafer laminate (hereinafter, steps (a) and (b)), wherein steps (c) to (e) are common to all aspects. (Aspect 1) (a1) a step of applying the temporary adhesive composition for wafer processing according to any one of claims 1 to 4 to a circuit-forming surface of a wafer having a circuit-forming surface on its front side and a circuit-free surface on its back side, and / or a bonding surface of a support to be bonded to the wafer, and bonding the composition to the wafer. (b1) photocuring the temporary adhesive of the bonded wafers (Aspect 2) (a2) a step of irradiating the temporary adhesive composition for wafer processing according to any one of claims 1 to 4 with light. (b2) applying the temporary adhesive composition for wafer processing irradiated with light in (a-2) to a circuit-forming surface of a wafer having a circuit-forming surface on its front side and a circuit-free surface on its back side, and / or a bonding surface of a support to be bonded to the wafer, and bonding the composition to the wafer. (c) A step of grinding or polishing the non-circuit-forming surfaces of the wafers of the wafer stack. (d) A step of processing the non-circuit-forming surface of the wafer. (e) peeling the processed wafer from the support.

6. 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 4 laminated thereon, and a wafer having a circuit-forming surface on a front surface and a circuit-free surface on a rear surface, The temporary adhesive layer is releasably adhered to the surface of the wafer.

Images