Protective sheet for semiconductor processing and method for manufacturing semiconductor device

Abstract

The present application provides a protective sheet for semiconductor processing which can sufficiently follow the unevenness of a wafer even when a semiconductor wafer having unevenness is thinned by DBG or the like and can suppress the generation of cracks in a chip after polishing. The protective sheet for semiconductor processing has a base material, and an intermediate layer and an adhesive layer in this order on one main surface of the base material; and satisfies the following (a) and (b): (a) the tangent of the loss angle of the intermediate layer at 50°C measured at a frequency of 1 Hz is 0.40 or more and 0.65 or less; (b) the ratio [A / I] of the storage modulus A of the adhesive layer at 50°C measured at a frequency of 1 Hz to the storage modulus I of the intermediate layer is 0.80 or more and 3.50 or less.

Description

Technical Field

[0001] This invention relates to a protective sheet for semiconductor processing and a method for manufacturing a semiconductor device. In particular, it relates to a protective sheet for semiconductor processing suitable for grinding the back side of a semiconductor wafer with uneven surfaces and for single-unitizing the semiconductor wafer using grinding stress or the like, and a method for manufacturing a semiconductor device using the protective sheet for semiconductor processing. Background Technology

[0002] In the process of miniaturization and multifunctionality of various electronic devices, the semiconductor chips used in these devices also require miniaturization and thinning. To achieve chip thinning, the back side of the semiconductor wafer is typically ground to adjust its thickness. Furthermore, to obtain thinner chips, a process called Dicing Before Grinding (DBG) is sometimes used. This process involves creating grooves of a specified depth on the wafer's surface using a dicing tool, followed by grinding from the back side of the wafer. This grinding process then individualizes the wafer into individual chips. DBG can simultaneously perform back-side grinding and wafer individualization, thus enabling efficient manufacturing of thin chips.

[0003] In the past, when performing back-side grinding of semiconductor wafers or manufacturing chips using DBG, adhesive tape known as back-grinding tape was usually attached to the wafer surface to protect the circuitry on the wafer surface or to maintain the semiconductor wafer and semiconductor chip.

[0004] As a backing abrasive used in DBG, an adhesive tape having a substrate and an adhesive layer disposed on one side of the substrate is used. As an example of such an adhesive tape, Patent Documents 1 and 2 disclose an adhesive tape having a substrate with a high Young's modulus, and having a buffer layer disposed on one side of the substrate and an adhesive layer disposed on the other side.

[0005] In recent years, as a variation of the pre-cutting method, a method has been proposed that uses a laser to create a modified region inside the wafer and utilizes the stress from grinding the back side of the wafer to achieve wafer unitization. Hereinafter, this method is sometimes referred to as LDBG (Laser Dicing Before Grinding). In LDBG, the wafer is cut along the crystal direction starting from the modified region, thus reducing chipping compared to pre-cutting methods using a dicing blade. This results in chips with excellent bending strength and facilitates further chip thinning. Furthermore, compared to DBG, which uses a dicing blade to form trenches of a specified depth on the wafer surface, LDBG achieves superior chip yield because there is no area where the wafer is removed by the dicing blade, resulting in a very small kerf width.

[0006] On the other hand, when mounting multi-pin LSI packages for MPUs or gate arrays on printed circuit boards, the flip-chip mounting method has always been used. In this mounting method, a chip with raised electrodes (bumps) made of eutectic solder, high-temperature solder, gold, etc., formed on its connecting pads is used as a semiconductor chip. These bumps are then brought into contact with corresponding terminals on the chip mounting substrate in a so-called face-down manner, and molten and diffused bonding is performed.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: International Publication No. 2015 / 156389

[0010] Patent Document 2: Japanese Patent Application Publication No. 2015-183008 Summary of the Invention

[0011] The technical problem to be solved by the present invention

[0012] The semiconductor chip used in this mounting method is obtained by monolithically processing a semiconductor wafer with uneven surfaces, such as a semiconductor wafer with convex electrodes. When this uneven semiconductor wafer is polished by DBG, as described above, back-polishing tape is attached to the circuit surface of the semiconductor wafer to protect the circuit surface during polishing and to prevent chip movement after wafer monolithization.

[0013] However, when the back-grinding tape described in Patent Document 1 and Patent Document 2 is attached to the circuit surface of a semiconductor wafer with unevenness and polished by DBG, the back-grinding tape described in Patent Document 1 and Patent Document 2 cannot fully follow the unevenness of the semiconductor wafer, resulting in problems such as water immersion into the circuit surface during polishing and chip movement (chip displacement) after wafer is monolithic.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a protective sheet for semiconductor processing that can fully follow the unevenness of the wafer even when thinning the semiconductor wafer with unevenness by DBG or the like, and can suppress the generation of cracks in the chip after grinding.

[0015] Technical means to solve technical problems

[0016] The present invention is as follows.

[0017] [1] A protective sheet for semiconductor processing, having a substrate and having an intermediate layer and an adhesive layer sequentially on a main surface of the substrate, and satisfying the following (a) and (b):

[0018] (a) The loss tangent of the intermediate layer at 50°C, measured at a frequency of 1 Hz, is greater than 0.40 and less than 0.65.

[0019] (b) The ratio of the energy storage modulus A of the adhesive layer to the energy storage modulus I of the intermediate layer at 50°C, measured at a frequency of 1 Hz, [A / I] is 0.80 or more and 3.50 or less.

[0020] [2] The protective sheet for semiconductor processing according to [1] has a buffer layer on another main surface of the substrate.

[0021] [3] The protective sheet for semiconductor processing according to [1] or [2], wherein the Young's modulus of the substrate is 1000 MPa or more.

[0022] [4] A protective sheet for semiconductor processing according to any one of [1] to [3], wherein the thickness of the intermediate layer is 60 μm or more and 250 μm or less.

[0023] [5] A protective sheet for semiconductor processing according to any one of [1] to [4], wherein the adhesive layer is energy-curable.

[0024] [6] A protective sheet for semiconductor processing according to any one of [1] to [5], wherein the intermediate layer is energy-curable.

[0025] [7] The semiconductor processing protective sheet according to any one of [1] to [6], wherein the semiconductor processing protective sheet is attached to the surface of the semiconductor wafer and used in the process of grinding the back side of a semiconductor wafer on which trenches are formed on the surface of the semiconductor wafer and then single-uniting the semiconductor wafer into a semiconductor chip by the grinding.

[0026] [8] A method for manufacturing a semiconductor device, comprising:

[0027] The process of attaching a protective sheet for semiconductor processing as described in any one of [1] to [7] to the surface of a semiconductor wafer with uneven surfaces;

[0028] The process of forming trenches from the surface side of a semiconductor wafer, or the process of forming modified regions inside a semiconductor wafer from the surface or back side of a semiconductor wafer;

[0029] A process of grinding semiconductor wafers with a protective film for semiconductor processing attached to their surface and with trenches or modified regions formed therein, starting from the back side, to single-chip out multiple wafers from the trenches or modified regions; and

[0030] The process of removing a protective film for semiconductor processing from a single semiconductor chip.

[0031] Invention Effects

[0032] According to the present invention, a protective sheet for semiconductor processing can be provided that can fully follow the unevenness of the wafer even when the semiconductor wafer is thinned by DBG or the like, and can suppress the generation of cracks in the chip after grinding. Attached Figure Description

[0033] Figure 1A This is a cross-sectional schematic diagram illustrating an example of a protective sheet for semiconductor processing according to this embodiment.

[0034] Figure 1B This is a cross-sectional schematic diagram illustrating another example of the semiconductor processing protective sheet of this embodiment.

[0035] Figure 2 This is a cross-sectional schematic diagram showing the state in which the protective sheet for semiconductor processing of this embodiment is attached to the circuit surface of a semiconductor wafer.

[0036] Explanation of reference numerals in the attached figures

[0037] 1: Protective film for semiconductor processing; 10: Substrate; 20: Intermediate layer; 30: Adhesive layer; 40: Buffer layer. Detailed Implementation

[0038] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, based on specific embodiments. First, the main terms used in this specification will be explained.

[0039] Semiconductor wafer modularization refers to dividing a semiconductor wafer into individual circuits to obtain a semiconductor chip.

[0040] The "surface" of a semiconductor wafer refers to the side where circuits, electrodes, etc. are formed, while the "back side" refers to the side where circuits, etc. are not formed.

[0041] DBG (Drilling-Groove) refers to a method of wafer monolithization, in which trenches of a specified depth are formed on the surface side of the wafer, followed by grinding from the back side. The trenches formed on the surface side of the wafer can be created using methods such as blade cutting, laser cutting, or plasma cutting.

[0042] In addition, LDBG is a variation of DBG, which refers to a method of using lasers to create modified regions inside the wafer and using stress during the grinding of the back side of the wafer to achieve wafer monolithization.

[0043] "Chipset" refers to a plurality of semiconductor chips held on a protective sheet for semiconductor processing in this invention after the semiconductor wafer is individually assembled. These semiconductor chips, as a whole, form a shape identical to that of the semiconductor wafer.

[0044] In this specification, for example, "(meth)acrylate" is used as a term to refer to "acrylate" and "methacrylate", and other similar terms are used in the same way.

[0045] "Energy rays" refer to ultraviolet rays, electron beams, etc., with ultraviolet rays being preferred.

[0046] (1. Protective film for semiconductor processing)

[0047] like Figure 1A As shown, the semiconductor processing protective sheet 1 of this embodiment has a structure in which an intermediate layer 20 and an adhesive layer 30 are sequentially stacked on a substrate 10.

[0048] The protective sheet for semiconductor processing in this embodiment is attached to a semiconductor wafer with uneven surfaces. For example, a semiconductor wafer with convex electrodes can be shown as a semiconductor wafer with uneven surfaces.

[0049] For example, such as Figure 2 As shown, the semiconductor processing protective sheet 1 of this embodiment is used such that its main surface 30a of the adhesive layer is attached to the bump forming surface 101a of a bumped semiconductor wafer, wherein bumps 102, which serve as convex electrodes, are formed on the semiconductor wafer 101. The bumps are formed in a manner that allows them to be electrically connected to the circuit formed on the semiconductor wafer, therefore the bump forming surface 101a is a circuit surface.

[0050] In this embodiment, a semiconductor wafer with bumps is monolithically processed into multiple semiconductor chips using a DBG or LDBG method. That is, before or after attaching a protective sheet for semiconductor processing, trenches are formed on the surface (circuit surface) or a modified region is formed inside the semiconductor wafer. Then, the side of the semiconductor wafer to which the protective sheet for semiconductor processing is attached, i.e., the back side, is polished.

[0051] When bumps and depressions such as convex electrodes are formed on a semiconductor wafer, if the thickness of the semiconductor wafer is reduced through grinding, the size of the bumps and depressions increases relatively with the thickness of the semiconductor wafer. Therefore, when the bumps and depressions are not properly embedded in the protective film for semiconductor processing, the following problems become more pronounced due to DBG or LDBG. That is, water seeps into the circuit surface of the semiconductor wafer during back-side grinding, adhesive residue remains on the cut when the protective film for semiconductor processing is peeled off after grinding, and the individual chips move after grinding, causing the chips to collide with each other and thus creating cracks on the chips.

[0052] The semiconductor processing protective sheet of this embodiment, having the intermediate layer and adhesive layer described later, can effectively suppress the occurrence of the above-mentioned problems.

[0053] Protective films for semiconductor processing are not limited to Figure 1A The structure described herein may also have other layers, as long as the effects of the present invention can be achieved. That is, as long as the substrate, intermediate layer and adhesive layer are stacked sequentially, other layers may be formed, for example, between the substrate and the intermediate layer, or between the intermediate layer and the adhesive layer.

[0054] In particular, in this embodiment, such as Figure 1B As shown, it is preferable to have a buffer layer 40 on the main surface of the substrate 10 opposite to the main surface where the adhesive layer 30 is formed. By having a buffer layer 40, the occurrence of the above-mentioned problems can be further suppressed.

[0055] The following is about Figure 1B The structural elements of the semiconductor processing protective sheet 1 shown are described in detail.

[0056] (2. Substrate)

[0057] As a substrate, there are no limitations as long as it is made of a material capable of supporting a semiconductor wafer. For example, various resin films used as substrates for back-grinding tapes can be exemplified. The substrate can be made of a single layer of resin film or a multilayer film consisting of multiple resin films stacked together.

[0058] (2.1 Physical properties of the substrate)

[0059] In this embodiment, the substrate preferably has high rigidity. Due to the high rigidity of the substrate, even if the thickness of the semiconductor wafer is reduced due to grinding, the wafer can be maintained without wafer breakage. Specifically, the Young's modulus of the substrate is preferably 1000 MPa or more, more preferably 1500 MPa or more, and even more preferably 2000 MPa or more.

[0060] In this embodiment, the thickness of the substrate is preferably 15 μm or more and 200 μm or less, and more preferably 40 μm or more and 150 μm or less.

[0061] (2.2 Material of the substrate)

[0062] The preferred material for the substrate is one whose Young's modulus is within the aforementioned range. In this embodiment, examples include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polyethylene terephthalate, and fully aromatic polyesters, as well as polyamides, polycarbonates, polyacetals, modified polyphenylene ethers, polyphenylene sulfides, polysulfones, polyetherketones, and biaxially stretched polypropylene. Polyesters are preferred, and polyethylene terephthalate is more preferred.

[0063] (3. Intermediate layer)

[0064] The intermediate layer is disposed between the substrate and the adhesive layer. In this embodiment, the intermediate layer, together with the adhesive layer, can fully follow the irregularities formed on the surface of the semiconductor wafer, embedding the irregularities into the adhesive layer and the intermediate layer. As a result, even when the semiconductor wafer is ground very thin and force is applied to convex electrodes, the adhesive layer and the intermediate layer can adequately protect the convex electrodes. Furthermore, when convex electrodes penetrate the adhesive layer, the intermediate layer embeds and protects them. The intermediate layer can be composed of a single layer or multiple layers of two or more.

[0065] The thickness of the intermediate layer 20 can be set taking into account the size of the unevenness of the semiconductor wafer, such as the height of the convex electrode. In this embodiment, the thickness of the intermediate layer 20 is preferably 60 μm or more and 250 μm or less, more preferably 100 μm or more and 200 μm or less. Furthermore, the thickness of the intermediate layer refers to the total thickness of the entire intermediate layer. For example, the thickness of an intermediate layer composed of multiple layers refers to the total thickness of all layers constituting the intermediate layer.

[0066] In this embodiment, the intermediate layer has the following physical properties.

[0067] (3.1 Loss tangent at 50℃)

[0068] In this embodiment, the loss tangent (tanδ) of the intermediate layer at 50°C is in the range of 0.40 to 0.65. The loss tangent is defined as "loss modulus / storage modulus", which is a value measured using a dynamic viscoelasticity measuring device and by the response to stress applied to an object.

[0069] By setting the loss tangent of the intermediate layer at 50°C to 0.40 or higher, the unevenness formed on the wafer surface is fully embedded in the semiconductor processing protective film, thus suppressing water immersion during polishing. Furthermore, by setting the loss tangent of the intermediate layer at 50°C to 0.65 or lower, chip displacement after wafer monolithization can be suppressed.

[0070] In addition, in this embodiment, when the intermediate layer has energy-curable properties, the loss tangent of the intermediate layer at 50°C is the same as the loss tangent before energy-curing.

[0071] The loss tangent of the intermediate layer at 50°C is preferably 0.42 or higher. Furthermore, the loss tangent of the intermediate layer at 50°C is preferably 0.64 or lower.

[0072] The loss tangent of the interlayer at 50°C can be determined using known methods. In this embodiment, the interlayer is prepared into a sample of a specified size, and the sample is deformed at a frequency of 1 Hz within a specified temperature range using a dynamic viscoelasticity measuring device. The elastic modulus is measured, and the loss tangent can be calculated from the measured elastic modulus.

[0073] (3.2 The ratio of the energy storage modulus I of the intermediate layer to the energy storage modulus A of the adhesive layer)

[0074] In this embodiment, when the energy storage modulus (G') of the intermediate layer at 50°C is set as energy storage modulus I, and the energy storage modulus (G') of the adhesive layer described later is set as energy storage modulus A, the ratio of energy storage modulus I to energy storage modulus A, "A / I", is 0.80 or more and 3.50 or less.

[0075] By setting the A / I ratio at 50°C to 0.80 or higher, the protective sheet for semiconductor processing fully follows the contours of the semiconductor wafer, and the embedding of the semiconductor wafer within the protective sheet becomes appropriate. As a result, water immersion during polishing can be suppressed. Furthermore, by setting the A / I ratio at 50°C to 3.50 or lower, adhesive adhesion to the cut surface during the removal of the protective sheet for semiconductor processing can be suppressed.

[0076] In addition, in this embodiment, when the intermediate layer has energy ray curing properties, the energy storage modulus I is the energy storage modulus before energy ray curing.

[0077] The energy storage modulus I is not particularly limited as long as it meets the range of "A / I" mentioned above. In this embodiment, the energy storage modulus I is preferably 0.03 MPa or more and 0.08 MPa or less.

[0078] The storage modulus (storage modulus I) of the intermediate layer at 50°C can be determined by known methods. For example, the intermediate layer is made into a sample of a specified size, and the sample is deformed at a frequency of 1 Hz within a specified temperature range using a dynamic viscoelasticity measuring device. The elastic modulus is then measured, and the storage modulus I can be calculated from the measured elastic modulus.

[0079] (3.3 Composition for intermediate layer)

[0080] As long as the intermediate layer possesses the aforementioned physical properties, there are no particular limitations on its composition. However, in this embodiment, it is preferable that the intermediate layer is composed of a resin-containing composition (intermediate layer composition). Specifically, it is preferable that the intermediate layer composition contains an acrylic polymer (A) with a weight-average molecular weight of 300,000 to 1,500,000 and an energy-curable acrylic polymer (B) with a weight-average molecular weight of 50,000 to 250,000. The acrylic polymer (A) can be either non-energy-curable or energy-curable, but in this embodiment, non-energy-curable is preferred.

[0081] Furthermore, unless otherwise specified, "weight-average molecular weight" in this specification refers to the converted value of polystyrene determined by gel permeation chromatography (GPC). For example, a high-speed GPC apparatus, the "HLC-8120GPC" manufactured by TOSOH, is used with a high-speed chromatographic column, "TSK gurd column H," sequentially connected to it. XL -H”, TSK GelGMH XL "TSK Gel G2000H" XL The measurements were performed using equipment (all manufactured by TOSOH) at a column temperature of 40°C and a delivery rate of 1.0 mL / min, with a differential refractive index meter as the detector.

[0082] (3.3.1 Acrylic polymers (A))

[0083] As described above, the acrylic polymer (A) can be either energy-curable or non-energy-curable. In this embodiment, the case where the acrylic polymer (A) is non-energy-curable will be described. The acrylic polymer (A) is preferably a non-energy-curable polymer having structural units derived from (meth)acrylates. Specifically, the acrylic polymer (A) is more preferably composed of an acrylic copolymer having structural units derived from alkyl (meth)acrylates (a1) and structural units derived from functionalized monomers (a2).

[0084] Alkyl methacrylates with 1 to 18 carbon atoms in the alkyl group can be used as alkyl methacrylates (a1). Specifically, examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, n-decyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, myristyl methacrylate, palmityl(meth)acrylate, and stearate methacrylate.

[0085] The alkyl methacrylate (a1) is preferably an alkyl methacrylate with 4 to 8 carbon atoms in the alkyl group. Specifically, n-butyl methacrylate is preferred. Furthermore, the alkyl methacrylate (a1) can be used alone or in combination of two or more.

[0086] The content of structural units derived from alkyl (meth)acrylate (a1) in acrylic polymer (A) is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, and even more preferably 80 to 95% by mass, relative to all structural units (100% by mass) of acrylic polymer (A).

[0087] If the content is 50% by mass or more, the retention performance of the adhesive sheet can be improved, and the following properties of the adhesive with large unevenness are improved. In addition, if it is 99.5% by mass or less, it can ensure that the structural units from component (a2) are in a certain quantity.

[0088] The functional group-containing monomer (a2) is a monomer having functional groups such as hydroxyl, carboxyl, epoxy, amino, cyano, nitrogen-containing cyclogroup, or alkoxysilyl. Preferably, the functional group-containing monomer (a2) is selected from one or more of hydroxyl-containing monomers, carboxyl-containing monomers, and epoxy-containing monomers.

[0089] Examples of hydroxyl-containing monomers include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, and other hydroxyalkyl methacrylates, as well as unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0090] Examples of carboxyl-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, and itaconic acid.

[0091] Examples of epoxy-containing monomers include epoxy-containing (meth)acrylates and non-acrylic epoxy-containing monomers. Examples of epoxy-containing (meth)acrylates include glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, (3,4-epoxycyclohexyl)meth(meth)acrylate, and 3-epoxycyclo-2-hydroxypropyl (meth)acrylate. Examples of non-acrylic epoxy-containing monomers include glycidyl crotonate and allyl glycidyl ether.

[0092] A single functional group monomer (a2) can be used alone, or two or more can be used in combination.

[0093] Among the functionalized monomers (a2), carboxyl-containing monomers are more preferred, with (meth)acrylic acid being even more preferred, and acrylic acid being the most preferred. When a carboxyl-containing monomer is used as the functionalized monomer (a2), the cohesive force of the interlayer increases, making it easier to improve the retention properties of the interlayer.

[0094] The content of structural units derived from functional monomers (a2) in acrylic polymer (A) is preferably 0.5 to 40% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, relative to all structural units (100% by mass) of acrylic polymer (A).

[0095] If the content of structural units from component (a2) is 0.5% by mass or more, the cohesion of the intermediate layer increases, and it is also easier to achieve good compatibility with component (B). On the other hand, if the content is 40% by mass or less, it is possible to ensure that the structural units from component (a1) are in a certain quantity.

[0096] The acrylic polymer (A) can be a copolymer of (meth)acrylate (a1) and a functional monomer (a2), but it can also be a copolymer of (a1), (a2) and other monomers (a3) ​​other than these (a1) and (a2) components.

[0097] Other monomers (a3) ​​include, for example, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, dicyclopentyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenoxyethyl methacrylate, and other cyclic methacrylates, vinyl acetate, styrene, etc. Other monomers (a3) ​​can be used alone or in combination of two or more.

[0098] The content of structural units derived from other monomers (a3) ​​in acrylic polymer (A) is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, relative to all structural units (100% by mass) of acrylic polymer (A).

[0099] The weight-average molecular weight (Mw) of the acrylic polymer (A) is preferably 300,000 to 1,500,000, more preferably 400,000 to 1,100,000, and even more preferably 450,000 to 900,000. By setting Mw below the above-mentioned upper limit, the compatibility between the acrylic polymer (A) and the acrylic polymer (B) becomes good. Furthermore, by setting Mw within the above range, the retention performance of the adhesive sheet can be easily improved.

[0100] The content of acrylic polymer (A) in the intermediate layer composition is preferably 40 to 95% by mass, more preferably 45 to 90% by mass, relative to the total amount (100% by mass) of the intermediate layer composition.

[0101] Furthermore, when the intermediate layer composition is diluted with a diluent such as an organic solvent as described later, the total amount of the intermediate layer composition represents the total amount of solid components excluding the diluent. The same applies to the adhesive layer composition described later.

[0102] (3.3.2 Acrylic polymers (B))

[0103] Acrylic polymer (B) is an acrylic polymer that possesses energy-ray curable properties by introducing energy-ray polymerizable groups. The weight-average molecular weight (Mw) of acrylic polymer (B) is 50,000 to 250,000. In this embodiment, by using component (B) in the intermediate layer, the convex electrode can be fully embedded during the backside grinding of the semiconductor wafer before energy-ray curing, and by performing energy-ray curing after grinding, cohesive destruction of the intermediate layer can be prevented, making it easy to peel off well from the semiconductor chip.

[0104] The weight-average molecular weight (Mw) of the acrylic polymer (B) is preferably 60,000 to 220,000, more preferably 70,000 to 200,000, and even more preferably 85,000 to 150,000.

[0105] Acrylic polymer (B) is an acrylic polymer that incorporates energy-beta polymerizable groups and has structural units derived from (meth)acrylates. The energy-beta polymerizable groups in acrylic polymer (B) are preferably incorporated into the side chains of the acrylic polymer. The energy-beta polymerizable groups can be groups containing energy-beta polymerizable carbon-carbon double bonds, such as (meth)acryloyl, vinyl, etc., with (meth)acryloyl being preferred.

[0106] The acrylic polymer (B) is preferably a reaction product obtained by reacting a polymerizable compound (Xb) having energy-ray polymerizable groups with an acrylic copolymer (B0), wherein the acrylic copolymer (B0) has structural units derived from alkyl (meth)acrylate (b1) and structural units derived from a functionalized monomer (b2).

[0107] Alkyl methacrylates with 1 to 18 carbon atoms in the alkyl group can be used as (meth)acrylate (b1). Specific examples include compounds exemplified by component (a1). Preferably, the (meth)acrylate (b1) is an alkyl methacrylate with 4 to 8 carbon atoms in the alkyl group. Specifically, n-butyl methacrylate is preferred. Furthermore, these alkyl methacrylates can be used alone or in combination of two or more.

[0108] Of the acrylic copolymer (B0), the content of structural units derived from alkyl methacrylate (b1) in the acrylic copolymer (B0) is preferably 50–95% by mass, more preferably 60–85% by mass, and even more preferably 65–80% by mass, relative to all structural units (100% by mass) of all structural units. If this content is 50% by mass or more, the shape of the formed intermediate layer can be adequately maintained. Furthermore, if it is 95% by mass or less, it can be ensured that the structural units derived from component (b2), which are the reaction sites with the polymerizable compound (Xb), are present in a certain amount.

[0109] As a functional group-containing monomer (b2), monomers having the functional groups exemplified in the above-described functional group-containing monomers (a2) can be listed, preferably selected from one or more of hydroxyl-containing monomers, carboxyl-containing monomers, and epoxy-containing monomers. As specific compounds of these functional group-containing monomers, compounds identical to those exemplified by components (a2) can be shown.

[0110] Furthermore, as the functionalized monomer (b2), a hydroxyl-containing monomer is preferred, and more preferably, various hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate. By using hydroxyalkyl methacrylates, the polymerizable compound (Xb) can be reacted with the acrylic copolymer (B0) more readily.

[0111] Furthermore, the functional groups in the functionalized monomer (a2) used in the acrylic polymer (A) and the functionalized monomer (b2) used in the acrylic polymer (B) may be the same or different, but are preferably different. That is, for example, if the functionalized monomer (a2) is a carboxyl-containing monomer, it is preferable that the functionalized monomer (b2) is a hydroxyl-containing monomer. In this way, when the functional groups are different, the acrylic polymer (B) can be preferentially crosslinked, for example, by using a crosslinking agent described later, which makes it easier to improve the retention properties of the adhesive sheet.

[0112] The content of structural units derived from functionalized monomers (b2) in the acrylic copolymer (B0) is preferably 10–45% by mass, more preferably 15–40% by mass, and even more preferably 20–35% by mass, relative to all structural units (100% by mass) of all structural units in the acrylic copolymer (B0). If it is 10% by mass or more, it ensures a greater number of reaction sites with the polymerizable compound (Xb), facilitating the introduction of energy-ray polymerizable groups into the side chains. Furthermore, if it is 45% by mass or less, the shape of the formed intermediate layer can be adequately maintained.

[0113] Acrylic copolymers (B0) can be copolymers of alkyl (meth)acrylate (b1) and functionalized monomers (b2), but can also be copolymers of components (b1), (b2), and other monomers (b3) besides these components (b1) and (b2).

[0114] Other monomers (b3) can be listed as monomers exemplified above (a3).

[0115] The content of structural units derived from other monomers (b3) in the acrylic copolymer (B0) is preferably 0 to 30% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, relative to all structural units (100% by mass) of all structural units of the acrylic copolymer (B0).

[0116] Polymerizable compounds (Xb) are compounds having energy-beam polymerizable groups and substituents (hereinafter sometimes simply referred to as "reactive substituents") capable of reacting with functional groups in structural units derived from component (b2) of acrylic copolymers (B0).

[0117] As described above, examples of energy-ray polymerizable groups include (meth)acryloyl and vinyl groups, with (meth)acryloyl being preferred. Furthermore, the polymerizable compound (Xb) is preferably a compound having 1 to 5 energy-ray polymerizable groups per molecule.

[0118] As a reactive substituent in the polymerizable compound (Xb), it can be appropriately modified according to the functional group possessed by the functional group-containing monomer (b2). For example, isocyanate group, carboxyl group, epoxy group, etc. can be listed. From the perspective of reactivity, isocyanate group is preferred. When the polymerizable compound (Xb) has an isocyanate group, for example, when the functional group of the functional group-containing monomer (b2) is hydroxyl, it can easily react with acrylic copolymer (B0).

[0119] Specific polymerizable compounds (Xb) include, for example, (meth)acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, (meth)acryloyl isocyanate, allyl isocyanate, (meth)acrylate glycidyl ester, (meth)acrylic acid, etc. These polymerizable compounds (Xb) can be used alone or in combination of two or more.

[0120] From the perspective of compounds having an isocyanate group suitable for use as the above-mentioned reactive substituent and having a suitable distance between the main chain and the energy-ray polymerizable group, (meth)acryloyloxyethyl isocyanate is preferred.

[0121] The polymerizable compound (Xb) preferably reacts with 40 to 98 equivalents of functional groups from the total amount (100 equivalents) of functional groups from the functional group-containing monomer (b2) in the acrylic polymer (B), more preferably with 60 to 90 equivalents of functional groups, and even more preferably with 70 to 85 equivalents of functional groups.

[0122] In the intermediate layer composition, the content of acrylic polymer (B) is preferably 5 to 60 parts by mass relative to 100 parts by mass of acrylic polymer (A), more preferably 10 to 50 parts by mass. By setting the content of component (B) to a relatively small amount, the intermediate layer can easily follow the unevenness of the semiconductor wafer.

[0123] (3.3.3 Crosslinking agent)

[0124] The intermediate layer composition preferably further contains a crosslinking agent. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents, among which isocyanate crosslinking agents are preferred. If an isocyanate crosslinking agent is used, for example, when component (B) has hydroxyl groups, the crosslinking agent preferentially crosslinks the acrylic polymer (B).

[0125] The intermediate layer composition is cross-linked using a cross-linking agent, for example, by heating after coating. Since the intermediate layer is cross-linked with acrylic polymers, especially low molecular weight acrylic polymers (B), it can be appropriately formed into a coating film and easily perform its function as an intermediate layer.

[0126] The content of crosslinking agent is preferably 0.1 to 10 parts by weight relative to 100 parts by weight of acrylic polymer (A), more preferably 0.5 to 7 parts by weight, and even more preferably 1 to 5 parts by weight.

[0127] Polyisocyanate compounds can be listed as crosslinking agents for isocyanates. Specific examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; and aliphatic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. Furthermore, their biuret forms, isocyanurate forms, and adducts as reaction products with low-molecular-weight compounds containing active hydrogen, such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil, can also be listed.

[0128] These isocyanate crosslinking agents can be used alone or in combination of two or more. Furthermore, polyol adducts (e.g., trimethylolpropane) of aromatic polyisocyanates such as toluene diisocyanate are preferred.

[0129] In addition, examples of epoxy crosslinking agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-phenylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxypropane diglycidyl ether, diglycidyl aniline, and diglycidylamine. These epoxy crosslinking agents can be used alone or in combination of two or more.

[0130] Examples of metal chelate crosslinking agents include compounds formed by coordination of acetylacetone, ethyl acetoacetate, tris(2,4-pentanedione) with polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. These metal chelate crosslinking agents can be used alone or in combination of two or more.

[0131] Examples of aziridine crosslinking agents include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane tri-β-aziridine propionate, tetramethylolmethane tri-β-aziridine propionate, toluene-2,4-bis(1-aziridinecarboxamide), triethylene melamine, bis(isophthaloyl-1-(2-methylaziridine), tri-1-(2-methylaziridine)phosphine, trimethylolpropane tri-β-(2-methylaziridine) propionate, and hexa[1-(2-methyl)-aziridine]triphosphatriazine.

[0132] (3.3.4 Photopolymerization Initiator)

[0133] The intermediate layer composition preferably further contains a photopolymerization initiator. By containing a photopolymerization initiator, the intermediate layer composition can be easily cured by energy rays such as ultraviolet light.

[0134] Examples of photopolymerization initiators include acetophenone, 2,2-diethoxybenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, michalcone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, benzyl dimethyl ketal, dibenzyl, diacetyl, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 1-hydroxycyclohexane. Low molecular weight polymerization initiators such as hexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylacetone-1,2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1,2-hydroxy-2-methyl-1-phenyl-propane-1-one, diethylthioxanone, isopropylthioxanone, and 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, as well as oligomerized polymerization initiators such as oligomerized {2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone}, are used. These photopolymerization initiators can be used alone or in combination of two or more. Furthermore, 1-hydroxycyclohexylphenyl ketone is preferred.

[0135] In order to ensure sufficient curing even when the content of acrylic polymer (B) is low, the content of photopolymerization initiator is preferably 1 to 10 parts by mass relative to 100 parts by mass of acrylic polymer (A), more preferably 2 to 8 parts by mass.

[0136] Without impairing the effects of the present invention, the intermediate layer composition may also contain other additives. Examples of other additives include antioxidants, plasticizers, fillers, rust inhibitors, pigments, dyes, and tackifiers. When these additives are present, the content of each additive is preferably 0.01 to 6 parts by weight, more preferably 0.01 to 2 parts by weight, relative to 100 parts by weight of the acrylic polymer (A).

[0137] Furthermore, the storage modulus and loss tangent of the intermediate layer can be adjusted, for example, when using an acrylic polymer (B), by the type and amount of monomers constituting the acrylic polymer (B), and the amount of energy-emitting polymeric groups introduced into the acrylic polymer (B). For example, increasing the amount of energy-emitting polymeric groups tends to increase the storage modulus. Moreover, it can also be appropriately adjusted by the amount of crosslinking agent and photopolymerization initiator incorporated into the intermediate layer.

[0138] (4. Adhesive layer)

[0139] An adhesive layer is attached to the circuit surface of a semiconductor wafer, protecting and supporting the semiconductor wafer until it is peeled off. In this embodiment, the adhesive layer, together with the intermediate layer, fully follows the irregularities formed on the surface of the semiconductor wafer, embedding these irregularities into the semiconductor processing protective sheet. As a result, even when the semiconductor wafer is ground to a very thin thickness and force is applied to the convex electrodes, the semiconductor processing protective sheet can adequately protect the convex electrodes, etc. Furthermore, even when the semiconductor wafer is monolithically processed, contact between semiconductor chips can be suppressed. In addition, the adhesive layer can consist of a single layer or multiple layers of two or more.

[0140] There is no particular limitation on the thickness of the adhesive layer, as long as it is sufficient to support the semiconductor wafer. In this embodiment, the thickness of the adhesive layer is preferably 5 μm to 500 μm, more preferably 8 μm to 100 μm. Furthermore, the thickness of the adhesive layer refers to the overall thickness of the adhesive layer. For example, the thickness of an adhesive layer composed of multiple layers refers to the total thickness of all layers constituting the adhesive layer.

[0141] In this embodiment, the adhesive layer has the following physical properties.

[0142] (4.1 Storage modulus A of the adhesive layer)

[0143] As described above, the storage modulus (G') of the adhesive layer at 50°C is denoted by storage modulus A. The storage modulus A is not limited as long as it satisfies the range of "A / I" mentioned above. In this embodiment, the storage modulus A is preferably 0.03 MPa or more and 0.15 MPa or less. Furthermore, the storage modulus A is more preferably 0.04 MPa or more, and even more preferably 0.12 MPa or more. Furthermore, the storage modulus A is more preferably 0.05 MPa or less, and even more preferably 0.10 MPa or less. Additionally, in this embodiment, when the adhesive layer has energy-ray curable properties, the storage modulus A is the storage modulus before energy-ray curing.

[0144] The storage modulus (storage modulus A) of the adhesive layer at 50°C can be determined by known methods. For example, the adhesive layer can be made into a sample of a specified size, and the sample can be deformed at a frequency of 1 Hz within a specified temperature range using a dynamic viscoelasticity measuring device. The elastic modulus can be measured, and the storage modulus A can be calculated from the measured elastic modulus.

[0145] (4.2 Composition for adhesive layer)

[0146] As long as the adhesive layer possesses the aforementioned physical properties, its composition is not particularly limited. In this embodiment, the adhesive layer is preferably composed of a resin-containing composition (adhesive layer composition). Specifically, the adhesive layer composition is preferably energy-curable. By making the adhesive layer composition energy-curable, it has a high adhesion that can sufficiently hold the semiconductor wafer before irradiation with energy rays, and after irradiation with energy rays, the adhesion of the adhesive layer decreases due to curing. Even when the semiconductor wafer, as the object to be bonded, is monolithically detached from the monolithically detached semiconductor chip, it is easy to peel off.

[0147] The composition for forming the adhesive layer contains, for example, acrylic polymers, polyurethanes, rubber polymers, polyolefins, silicones, etc., as adhesive components (adhesive resins) that enable the adhesive layer to exhibit adhesiveness. Among these, acrylic polymers are preferred.

[0148] For adhesive layer compositions that form adhesive layers, energy-curable properties can be achieved by incorporating energy-curable compounds different from the adhesive resin, but it is preferable that the adhesive resin itself has energy-curable properties. When the adhesive resin itself has energy-curable properties, energy-curable polymeric groups are introduced into the adhesive resin, and these energy-curable polymeric groups are preferably introduced into the main chain or side chain of the adhesive resin.

[0149] Furthermore, when incorporating an energy-curable compound different from the adhesive resin, monomers or oligomers having energy-curable groups can be used as the energy-curable compound. The oligomer is a weight-average molecular weight (Mw) less than 10,000, such as urethane (meth)acrylate. Moreover, even when the adhesive resin itself is energy-curable, an energy-curable compound can be incorporated into the adhesive layer composition in addition to the adhesive resin.

[0150] The following provides a more detailed explanation of the case where the adhesive layer contains an energy-curable adhesive resin that is an acrylic polymer (hereinafter also referred to as "acrylic polymer (C)").

[0151] (4.2.1 Acrylic polymers (C))

[0152] Acrylic polymer (C) is an acrylic polymer that incorporates energy-beta polymerizable groups and has structural units derived from (meth)acrylates. The energy-beta polymerizable groups are preferably incorporated into the side chains of the acrylic polymer.

[0153] The acrylic polymer (C) is preferably a reaction product obtained by reacting a polymerizable compound (Xc) having energy-ray polymerizable groups with an acrylic copolymer (C0), wherein the acrylic copolymer (C0) has structural units derived from alkyl (meth)acrylate (C1) and structural units derived from a functionalized monomer (C2).

[0154] As the alkyl methacrylate (c1), an alkyl methacrylate having 1 to 18 carbon atoms in the alkyl group can be used. Specific examples include alkyl methacrylates with 1 to 18 carbon atoms in the alkyl group, as exemplified by component (a1). Preferably, the alkyl methacrylate (c1) has 4 to 8 carbon atoms in the alkyl group. Specifically, 2-ethylhexyl methacrylate and n-butyl methacrylate are preferred, and n-butyl methacrylate is more preferred. Furthermore, one of these alkyl methacrylates can be used alone, or two or more can be used in combination.

[0155] From the perspective of improving the adhesion of the formed adhesive layer, the content of structural units derived from (meth)acrylate (c1) in the acrylic copolymer (C0) is preferably 50 to 99% by mass, more preferably 60 to 97% by mass, and even more preferably 70 to 96% by mass, relative to all structural units (100% by mass) of the acrylic copolymer (C0).

[0156] For example, in addition to 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate mentioned above, alkyl (meth)acrylate (C1) may also contain ethyl (meth)acrylate and methyl (meth)acrylate. By including these monomers, the adhesive properties of the adhesive layer can be easily adjusted to the desired adhesive properties.

[0157] As a functional group-containing monomer (c2), examples can be given of monomers having the functional groups exemplified by the functional group-containing monomer (a2) described above. Specifically, it is preferably selected from one or more monomers containing hydroxyl groups, carboxyl groups, and epoxy groups. As specific compounds of these functional group-containing monomers, compounds identical to those exemplified by component (a2) can be given.

[0158] As a functional group-containing monomer (c2), among the above monomers, hydroxyl-containing monomers are more preferred, among which hydroxyalkyl esters of (meth)acrylate are more preferred, 2-hydroxyethyl esters of (meth)acrylate and 4-hydroxybutyl esters of (meth)acrylate are even more preferred, and 4-hydroxybutyl esters of (meth)acrylate are particularly preferred.

[0159] By using hydroxyalkyl methacrylate as component (C2), the polymerizable compound (XC) can be reacted with the acrylic copolymer (C0) more readily. Furthermore, when 4-hydroxybutyl methacrylate is used, the tensile strength of the interlayer increases, making it easier to prevent adhesive residue.

[0160] The content of structural units derived from functional monomers (c2) in the acrylic copolymer (C0) is preferably 1 to 40% by mass, more preferably 2 to 35% by mass, and even more preferably 3 to 30% by mass, relative to all structural units (100% by mass) of all structural units in the acrylic copolymer (C0).

[0161] If the content is 1% by mass or more, it ensures that the functional groups that are reaction sites with the polymerizable compound (Xc) are present in a certain amount. Therefore, the adhesive layer can be properly cured by irradiation with energy rays, thus reducing the adhesion after irradiation with energy rays. Furthermore, it is easy to improve the interlayer strength between the adhesive layer and the intermediate layer after irradiation with energy rays. In addition, if the content is 40% by mass or less, a sufficient pot life can be ensured when the adhesive layer is formed by applying a solution of the composition to the adhesive layer.

[0162] Acrylic copolymers (C0) can be copolymers of alkyl (meth)acrylate (C1) and functionalized monomers (C2), but can also be copolymers of components (C1), (C2), and other monomers (C3) besides these components (C1) and (C2).

[0163] Other monomers (c3) can be listed as examples of the monomers (a3) ​​mentioned above.

[0164] The content of structural units derived from other monomers (c3) in the acrylic copolymer (C0) is preferably 0 to 30% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, relative to all structural units (100% by mass) of all structural units of the acrylic copolymer (C0).

[0165] Similar to the polymerizable compound (Xb) described above, the polymerizable compound (Xc) is a compound having energy-beam polymerizable groups and substituents (reactive substituents) that can react with functional groups from the structural units of the (c2) component in the acrylic copolymer (C0), preferably a compound having 1 to 5 energy-beam polymerizable groups per molecule.

[0166] Specific examples of reactive substituents and energy-beam polymerizable groups are the same as those of polymerizable compound (Xb), therefore, the reactive substituent is preferably an isocyanate group, and the energy-beam polymerizable group is preferably a (meth)acryloyl group.

[0167] Furthermore, as specific polymerizable compounds (Xc), compounds identical to those exemplified by polymerizable compound (Xb) described above can be listed, with (meth)acryloyloxyethyl isocyanate being preferred. Additionally, polymerizable compounds (Xc) can be used alone or in combination of two or more.

[0168] The polymerizable compound (Xc) preferably reacts with 30 to 98 equivalents of functional groups from the total amount (100 equivalents) of functional groups from the functional group-containing monomer (C2) in the acrylic polymer (C0), more preferably with 40 to 95 equivalents of functional groups.

[0169] The weight-average molecular weight (Mw) of the acrylic polymer (C) is preferably 100,000 to 1,500,000, more preferably 250,000 to 1,000,000, and even more preferably 350,000 to 800,000. By having such a Mw, the adhesive layer can be given appropriate adhesion.

[0170] Even when the adhesive resin has energy-curable properties, it is preferable to include an energy-curable compound other than the adhesive resin in the composition for the adhesive layer. As such an energy-curable compound, monomers or oligomers having unsaturated groups in their molecules and capable of polymerization and curing by irradiation with energy rays are preferred.

[0171] Specifically, examples include trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol (meth)acrylate and other poly(meth)acrylate monomers, urethane (meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates, epoxy (meth)acrylates and other oligomers.

[0172] Among them, from the perspective of higher molecular weight and less reduction of the elastic modulus of adhesive layer, urethane (meth)acrylate oligomers are preferred.

[0173] (4.2.2 Crosslinking agent)

[0174] The adhesive layer composition preferably further contains a crosslinking agent. The adhesive layer composition is crosslinked, for example, by heating after coating, using a crosslinking agent. In the adhesive layer, the acrylic polymer (C) is crosslinked by the crosslinking agent, thereby enabling the proper formation of a coating film and facilitating its function as an adhesive layer.

[0175] Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and chelate crosslinking agents, with isocyanate crosslinking agents being preferred. Crosslinking agents can be used alone or in combination of two or more. Furthermore, specific examples of isocyanate crosslinking agents include those exemplified as crosslinking agents suitable for use in intermediate layer compositions, and the preferred isocyanate crosslinking agents are also the same.

[0176] The content of crosslinking agent is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of acrylic polymer (C), more preferably 0.1 to 7 parts by mass, and even more preferably 0.3 to 4 parts by mass.

[0177] (4.2.3 Photopolymerization initiator)

[0178] The adhesive layer composition preferably further contains a photopolymerization initiator. Examples of photopolymerization initiators include the compounds described above used in the intermediate layer composition. Furthermore, the photopolymerization initiator can be used alone or in combination of two or more. Among the above-mentioned photopolymerization initiators, 2,2-dimethoxy-1,2-diphenylethane-1-one and 1-hydroxycyclohexylphenyl one are preferred.

[0179] The content of photopolymerization initiator is preferably 0.5 to 15 parts by mass relative to 100 parts by mass of acrylic polymer (C), more preferably 1 to 12 parts by mass, and even more preferably 4.5 to 10 parts by mass.

[0180] Without impairing the effects of the present invention, the adhesive layer composition may also contain other additives. Examples of other additives include tackifiers, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. When these additives are contained, the content of each additive is preferably 0.01 to 6 parts by weight, more preferably 0.02 to 2 parts by weight, relative to 100 parts by weight of the acrylic polymer (C).

[0181] Furthermore, the storage modulus and loss tangent of the adhesive layer can be adjusted, for example, when using acrylic polymers (C), by the type and amount of monomers constituting the acrylic polymer (C), and the amount of energy-emitting polymeric groups introduced into the acrylic polymer (C). For example, increasing the amount of energy-emitting polymeric groups tends to increase the elastic modulus. Moreover, it can also be appropriately adjusted by the amount of crosslinking agent and photopolymerization initiator incorporated into the adhesive layer.

[0182] (5. Buffer layer)

[0183] like Figure 1BAs shown, a buffer layer is formed on the main surface of the substrate opposite to the main surface where the adhesive layer is formed. The buffer layer 40 is a layer softer than the substrate, which relieves stress during the grinding of the back side of the semiconductor wafer and prevents cracks and defects from forming on the semiconductor wafer. Furthermore, during the grinding of the back side, the semiconductor wafer with the semiconductor processing protective sheet attached is placed on the vacuum table in between the semiconductor processing protective sheet, but because the buffer layer serves as a structural layer for the semiconductor processing protective sheet, it is easy to hold it properly on the vacuum table.

[0184] The thickness of the buffer layer is preferably 1–100 μm, more preferably 5–80 μm, and even more preferably 10–60 μm. By setting the thickness of the buffer layer within the above range, the buffer layer can appropriately alleviate the stress during grinding of the back side.

[0185] The buffer layer can be a layer formed by a composition of a buffer layer containing a polymerizable compound containing energy rays, or it can be a polypropylene film, an ethylene-vinyl acetate copolymer film, an ionomer resin film, an ethylene-(meth)acrylic acid copolymer film, an ethylene-(meth)acrylic acid copolymer film, an LDPE film, an LLDPE film, etc.

[0186] In addition, a substrate with a buffer layer can be obtained by laminating a buffer layer on one or both sides of the substrate.

[0187] (5.1 Composition for buffer layer)

[0188] The composition of the buffer layer containing energy-ray polymerizable compounds can be cured by irradiation with energy rays.

[0189] Furthermore, more specifically, the buffer layer composition containing an energy-emitting polymerizable compound preferably contains urethane (meth)acrylate (d1) and a polymerizable compound having an alicyclic or heterocyclic group having 6 to 20 cyclic atoms (d3). In addition to the components (d1) and (d3) mentioned above, the buffer layer composition may also contain a multifunctional polymerizable compound (d2) and / or a polymerizable compound having functional groups (d4). Furthermore, in addition to the components mentioned above, the buffer layer composition may also contain a photopolymerization initiator. Moreover, the buffer layer composition may also contain other additives or resin components within a range that does not impair the effects of the present invention.

[0190] The following is a detailed description of the components contained in the composition for a buffer layer containing an energy-ray polymerizable compound.

[0191] (5.1.1 Carbamate (meth)acrylate (d1))

[0192] urethane (meth)acrylate (d1) is a compound having at least a (meth)acryloyl group and an urethane bond, which has the property of being polymerized and cured by irradiation with energy rays. Uramel (meth)acrylate (d1) is an oligomer or polymer.

[0193] The weight-average molecular weight (Mw) of component (d1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and even more preferably 3,000 to 20,000. Furthermore, the number of (meth)acryloyl groups in component (d1) (hereinafter also referred to as "number of functional groups") can be monofunctional, difunctional, or trifunctional or more, but monofunctional or difunctional is preferred.

[0194] Component (d1) can be obtained by reacting a hydroxyl-containing (meth)acrylate with a terminal isocyanate urethane prepolymer, which is obtained by reacting a polyol compound with a polyisocyanate compound. Furthermore, component (d1) can be used alone or in combination of two or more components.

[0195] The polyol compound used as a raw material for component (d1) is not particularly limited as long as it has two or more hydroxyl groups. It can be any of the following: difunctional diol, trifunctional triol, or polyol with more than four functionalities, but difunctional diols are preferred, and polyester-type diols or polycarbonate-type diols are more preferred.

[0196] Examples of polyisocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate, and dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, dimethylbiphenyl diisocyanate, tetramethylene xylene diisocyanate, and naphthalene-1,5-diisocyanate.

[0197] Among them, isophorone diisocyanate, hexamethylene diisocyanate, and xylene diisocyanate are preferred.

[0198] By reacting a hydroxyl-containing (meth)acrylate with a terminal isocyanate urethane prepolymer, urethane (meth)acrylate (d1) can be obtained, wherein the terminal isocyanate urethane prepolymer is obtained by reacting the aforementioned polyol compound with a polyisocyanate compound. There is no particular limitation on the hydroxyl-containing (meth)acrylate, as long as it is a compound having both a hydroxyl group and a (meth)acryloyl group in at least one molecule.

[0199] Specific examples of hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and other hydroxyalkyl (meth)acrylates; hydroxyl-containing (meth)acrylamides such as N-hydroxymethyl (meth)acrylamide; and reaction products obtained by reacting (meth)acrylate with diglycidyl esters of vinyl alcohol, vinyl phenol, or bisphenol A.

[0200] Preferably, hydroxyalkyl methacrylate is used, and more preferably, 2-hydroxyethyl methacrylate is used.

[0201] As for the conditions for reacting the terminal isocyanate urethane prepolymer and the hydroxyl-containing (meth)acrylate, it is preferable to react at 60 to 100°C for 1 to 4 hours in the presence of a solvent and catalyst added as needed.

[0202] The content of component (d1) in the buffer layer composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and even more preferably 25 to 55% by mass, relative to the total amount (100% by mass) of the buffer layer composition.

[0203] (5.1.2 Multifunctional polymeric compounds (d2))

[0204] Multifunctional polymerizable compounds are compounds containing two or more photopolymerizable unsaturated groups. These photopolymerizable unsaturated groups are functional groups containing carbon-carbon double bonds, such as (meth)acryloyl, vinyl, allyl, and vinylbenzyl. Two or more photopolymerizable unsaturated groups can also be used in combination. A three-dimensional network structure (cross-linked structure) is formed by reacting the photopolymerizable unsaturated groups in the multifunctional polymerizable compound with the (meth)acryloyl group in component (d1) or with each other in component (d2). When using multifunctional polymerizable compounds, compared to using compounds containing only one photopolymerizable unsaturated group, the cross-linked structure formed by irradiation with energy rays increases, thus the buffer layer exhibits unique viscoelasticity, easily relieving stress during back-side grinding.

[0205] Furthermore, there is overlap between the definition of component (d2) and the definitions of component (d3) or component (d4) described later, but the overlap is included in component (d2). For example, a compound having an alicyclic or heterocyclic group with 6 to 20 cyclic atoms and having two or more (meth)acryloyl groups is included in both definitions of component (d2) and component (d3), but in this invention, such a compound is considered to be included in component (d2). Similarly, a compound containing functional groups such as hydroxyl, epoxy, amide, or amino groups and having two or more (meth)acryloyl groups is included in both definitions of component (d2) and component (d4), but in this invention, such a compound is considered to be included in component (d2).

[0206] From the above perspective, the number of photopolymerizable unsaturated groups (functional groups) in a multifunctional polymerizable compound is preferably 2 to 10, more preferably 3 to 6.

[0207] Furthermore, the weight-average molecular weight of component (d2) is preferably 30 to 40,000, more preferably 100 to 10,000, and even more preferably 200 to 1,000.

[0208] Specific components (d2) may include, for example, diethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, vinyl(meth)acrylate, divinyl adipate, N,N'-methylenebis(meth)acrylamide, etc. Dipentaerythritol hexa(meth)acrylate is preferred. Furthermore, components (d2) may be used alone or in combination of two or more.

[0209] The content of component (d2) in the buffer layer composition is preferably 0 to 40% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, relative to the total amount (100% by mass) of the composition for the buffer layer.

[0210] (5.1.3 Polymerizable compounds having alicyclic or heterocyclic groups with 6 to 20 cyclic atoms (d3))

[0211] Component (d3) is a polymeric compound having an alicyclic or heterocyclic group having 6 to 20 cyclic atoms, and preferably a compound having at least one (meth)acryloyl group, more preferably a compound having one (meth)acryloyl group. By using component (d3), the film-forming properties of the obtained buffer layer composition can be improved.

[0212] Furthermore, there is overlap between the definition of component (d3) and the definition of component (d4) described later, but the overlap is included in component (d4). For example, although a compound having at least one (meth)acryloyl group, an alicyclic or heterocyclic group having 6 to 20 cyclic atoms, and functional groups such as hydroxyl, epoxy, amide, and amino groups is included in both definitions of component (d3) and component (d4), in this invention, such a compound is considered to be included in component (d4).

[0213] Specific examples of ingredient (d3) include isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentyl methacrylate, dicyclopentenoxy(meth)acrylate, cyclohexyl methacrylate, adamantane methacrylate, and other alicyclic (meth)acrylates; as well as heterocyclic (meth)acrylates such as tetrahydrofurfuryl methacrylate and morpholine(meth)acrylate. Furthermore, ingredient (d3) can be used alone or in combination of two or more.

[0214] Among (meth)acrylates containing alicyclic groups, isobornyl (meth)acrylate is preferred, and among (meth)acrylates containing heterocyclic groups, tetrahydrofurfuryl (meth)acrylate is preferred.

[0215] The content of component (d3) in the buffer layer composition is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and even more preferably 25 to 60% by mass, relative to the total amount (100% by mass) of the composition for the buffer layer.

[0216] (5.1.4 Polymers with functional groups (d4))

[0217] Component (d4) is a polymeric compound containing functional groups such as hydroxyl, epoxy, amide, and amino groups, and is preferably a compound having at least one (meth)acryloyl group, more preferably a compound having one (meth)acryloyl group.

[0218] Component (d4) and component (d1) are well compatible, making it easy to adjust the viscosity of the composition for the buffer layer to a suitable range. Furthermore, even when the buffer layer is made relatively thin, the buffering performance is good.

[0219] Examples of components (d4) include (meth)acrylates containing hydroxyl groups, compounds containing epoxy groups, compounds containing amide groups, and (meth)acrylates containing amino groups. Among these, (meth)acrylates containing hydroxyl groups are preferred.

[0220] Examples of hydroxyl-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate. Among these, hydroxyl-containing (meth)acrylates having an aromatic ring, such as phenylhydroxypropyl (meth)acrylate, are more preferred. Furthermore, component (d4) can be used alone or in combination of two or more.

[0221] To improve the film-forming properties of the buffer layer composition, the content of component (d4) in the buffer layer composition is preferably 0 to 40% by mass, more preferably 7 to 35% by mass, and even more preferably 10 to 30% by mass, relative to the total amount (100% by mass) of the buffer layer composition.

[0222] (5.1.5 Polymers other than components (d1) to (d4) (d5))

[0223] Without impairing the effects of the present invention, the composition for the buffer layer may also contain other polymeric compounds (d5) besides the components (d1) to (d4) mentioned above.

[0224] Examples of components (d5) include alkyl (meth)acrylates having alkyl groups having 1 to 20 carbon atoms, styrene, hydroxyethyl vinyl ethers, hydroxybutyl vinyl ethers, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, and other vinyl compounds. Furthermore, components (d5) can be used alone or in combination of two or more.

[0225] The content of component (d5) in the composition for the buffer layer is preferably 0-20% by mass, more preferably 0-10% by mass, further preferably 0-5% by mass, and particularly preferably 0-2% by mass.

[0226] (5.1.6 Photopolymerization Initiator)

[0227] From the perspective of shortening the light-based polymerization time and reducing the amount of light irradiation when forming the buffer layer, the composition for the buffer layer preferably further contains a photopolymerization initiator.

[0228] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, phosphine oxide compounds, titanocetamene compounds, thioxanthone compounds, peroxides, and photosensitizers such as amines or quinones. More specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloroanthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. These photopolymerization initiators can be used alone or in combination of two or more.

[0229] The content of photopolymerization initiator in the composition for the buffer layer is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass, relative to the total amount of energy-ray polymerizable compound (100 parts by mass).

[0230] (5.1.7 Other additives)

[0231] Without impairing the effects of the present invention, the composition for the buffer layer may also contain other additives. Examples of other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. When these additives are incorporated, the content of each additive in the composition for the buffer layer is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the total amount of energy-ray polymerizable compound.

[0232] A buffer layer formed from a buffer layer composition containing an energy-ray polymerizable compound is obtained by polymerizing and curing the aforementioned buffer layer composition by irradiating it with energy rays. In other words, the buffer layer is a product formed by curing the buffer layer composition.

[0233] Therefore, the buffer layer preferably contains polymeric units from component (d1) and polymeric units from component (d3). Furthermore, the buffer layer may also contain polymeric units from component (d2) and / or from component (d4), and may also contain polymeric units from component (d5). The proportion of each polymeric unit in the buffer layer is generally consistent with the proportion (addition ratio) of each component in the composition constituting the buffer layer.

[0234] (6. Peeling tablets)

[0235] Release tabs can be attached to the surface of the protective sheet for semiconductor processing. Specifically, the release tabs are attached to the surface of the adhesive layer of the protective sheet for semiconductor processing. By attaching to the surface of the adhesive layer, the release tabs protect the adhesive layer during transportation and storage. The release tabs are attached to the protective sheet for semiconductor processing in a peelable manner and are removed from the protective sheet before use (i.e., before attaching the wafer).

[0236] A release sheet is a release sheet in which at least one side has been subjected to a release treatment. Specifically, examples include release sheets made by coating a release agent on the surface of a substrate for release sheets.

[0237] As the substrate for the release liner, a resin film is preferred. Examples of resins constituting the resin film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin, as well as polyolefin resins such as polypropylene resin and polyethylene resin. Examples of release agents include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, and fluorinated resins.

[0238] The thickness of the release sheet is not particularly limited, but it is preferably 10 to 200 μm, more preferably 20 to 150 μm.

[0239] (7. Manufacturing method of protective film for semiconductor processing)

[0240] The method for manufacturing the semiconductor processing protective sheet of this embodiment is not particularly limited as long as it is a method that can form an intermediate layer and an adhesive layer on one main surface of the substrate and a buffer layer on the other main surface of the substrate, and a known method can be used.

[0241] First, for example, a composition for forming an intermediate layer containing the above-mentioned components is prepared, or a composition for forming an intermediate layer is prepared by diluting the composition for forming an intermediate layer with a solvent or the like, as a composition for forming an intermediate layer.

[0242] Similarly, for example, a composition for forming an adhesive layer containing the above-mentioned components, or a composition obtained by diluting the composition for forming an adhesive layer with a solvent or the like, can be prepared as an adhesive layer composition for forming an adhesive layer. Similarly, for example, a composition for forming a buffer layer containing the above-mentioned components, or a composition obtained by diluting the composition for forming a buffer layer with a solvent or the like, can be prepared as a buffer layer composition for forming a buffer layer.

[0243] Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.

[0244] Next, using known methods such as spin coating, spray coating, bar coating, knife coating, roller coating, blade coating, mold coating, and gravure coating, the buffer layer composition is applied to the release surface of the first release sheet to form a coating film. This coating film is then semi-cured to form a buffer layer film on the release sheet. The buffer layer film formed on the release sheet is then bonded to a substrate, and the buffer layer film is allowed to fully cure, thereby forming the buffer layer.

[0245] In this embodiment, curing of the coating is preferably performed by irradiation with energy rays. Furthermore, the curing of the coating can be carried out in a single curing process or in multiple stages.

[0246] Next, the intermediate layer is coated with the composition onto the release treatment surface of the second release sheet using a known method and then heated and dried to form an intermediate layer on the second release sheet. Then, the intermediate layer on the second release sheet is bonded to the side of the substrate where the buffer layer is not formed, and the second release sheet is removed.

[0247] Next, an adhesive layer is applied to the release surface of the third release sheet using a known method and then heated and dried to form an adhesive layer on the third release sheet. Then, by bonding the adhesive layer on the third release sheet to the intermediate layer, a semiconductor processing protective sheet is obtained in which an intermediate layer and an adhesive layer are sequentially formed on one main surface of the substrate, and a buffer layer is formed on the other main surface of the substrate. The third release sheet can be removed when using the semiconductor processing protective sheet.

[0248] (8. Manufacturing method of semiconductor device)

[0249] The semiconductor processing protective sheet of the present invention is preferably used when it is attached to the surface of a semiconductor wafer in a DBG and the back side of the wafer is polished. In particular, the semiconductor processing protective sheet of this embodiment is preferably used in an LDBG, which can obtain a chip assembly with a small kerf width when the semiconductor wafer is monolithically processed.

[0250] As a non-limiting example of the use of protective sheets for semiconductor processing, the manufacturing method of semiconductor devices will be further described below.

[0251] Specifically, the manufacturing method of a semiconductor device includes at least the following steps 1 to 4.

[0252] Step 1: The process of attaching the above-mentioned semiconductor processing protective sheet to the surface of a semiconductor wafer with uneven surfaces;

[0253] Step 2: A step of forming trenches from the surface side of the semiconductor wafer, or forming modified regions inside the semiconductor wafer from the surface or back side of the semiconductor wafer;

[0254] Step 3: A semiconductor wafer with a protective sheet for semiconductor processing attached to its surface and the aforementioned trenches or modified regions formed thereon is ground from the back side, and is converted into multiple chips starting from the trenches or modified regions.

[0255] Step 4: The process of peeling the semiconductor processing protective film off the monolithized semiconductor wafer (i.e., multiple semiconductor chips).

[0256] The following is a detailed description of each step in the manufacturing method of the above-mentioned semiconductor device.

[0257] (Process 1)

[0258] In step 1, the semiconductor processing protective sheet of the present invention is attached to the surface of a semiconductor wafer with unevenness via an adhesive layer. This step can be performed before or after step 2, which will be described later. For example, when a modified region is formed in the semiconductor wafer, step 1 is preferably performed before step 2. On the other hand, when trenches are formed on the surface of the semiconductor wafer by dicing or the like, step 1 is performed after step 2. That is, the semiconductor processing protective sheet is attached to the trenched wafer surface formed by step 2, which will be described later, through step 1.

[0259] The semiconductor wafer used in this manufacturing method can be a silicon wafer, or it can be a wafer made of gallium arsenide, silicon carbide, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or a glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is typically around 500–1000 μm. Furthermore, circuits are typically formed on the surface of the semiconductor wafer. Circuits can be formed on the wafer surface using various conventional methods, including etching and lift-off. In particular, in this embodiment, convex electrodes (bumps) are formed on the circuit surface of the semiconductor wafer. As a result, compared to a semiconductor wafer without convex electrodes, there are uneven surfaces on the circuit surface of the semiconductor wafer. Additionally, the height of the convex electrodes is not particularly limited, but is typically 5–200 μm.

[0260] (Process 2)

[0261] In step 2, trenches are formed from the surface side of the semiconductor wafer, or modified regions are formed from the surface or back side of the semiconductor wafer inside the semiconductor wafer.

[0262] The trenches formed in this process are shallower than the thickness of the semiconductor wafer. Conventional wafer dicing equipment can be used to form the trenches by cutting. Furthermore, the semiconductor wafer is diced into multiple semiconductor chips along the trenches in process 3, which will be described later.

[0263] Furthermore, the modified region is the brittle portion of the semiconductor wafer, marking the starting point for the individual semiconductor chips. In this individualization process, the semiconductor wafer is thinned through grinding during the polishing process, and the force generated by the polishing is applied, thereby breaking the semiconductor wafer and ultimately individualizing it into semiconductor chips. That is, the trenches and modified regions in process 2 are formed along the dividing lines used in the subsequent process 3 to segment the semiconductor wafer and then individualize it into semiconductor chips.

[0264] A modified region is formed by focusing laser irradiation on the interior of a semiconductor wafer. The laser irradiation can be performed from either the surface or the back side of the semiconductor wafer. Alternatively, in one method of forming the modified region, when step 2 is performed after step 1 and laser irradiation is performed from the wafer surface, the laser is irradiated onto the semiconductor wafer through a protective sheet used for semiconductor processing.

[0265] A semiconductor wafer, with a protective film for semiconductor processing attached and having trenches or modified regions formed thereon, is placed on a chuck table and held thereby. At this time, the surface side of the semiconductor wafer is positioned and held against the table side.

[0266] (Process 3)

[0267] After process 1 and process 2, the back side of the semiconductor wafer on the chuck table is ground to convert the semiconductor wafer into multiple semiconductor chips.

[0268] Here, when trenches are formed on a semiconductor wafer, back-side grinding is performed to thin the semiconductor wafer to at least reach the bottom of the trenches. Through this back-side grinding, the trenches are formed into cuts that penetrate the wafer, and the semiconductor wafer is divided through these cuts into individual semiconductor chips.

[0269] On the other hand, when a modified region is formed, the grinding surface (back side of the wafer) can reach the modified region through grinding, but it can also reach it imprecisely. That is, grinding can be done close to the modified region in a way that allows the semiconductor wafer to be broken down from the modified region and thus monolithically formed into a semiconductor chip. For example, the actual monolithization of the semiconductor chip can be performed by extending the pick-up tape after attaching the pick-up tape described later.

[0270] In addition, dry polishing can be performed after the back-side grinding is completed and before the chip is picked up.

[0271] The shape of the monolithic semiconductor chip can be square or rectangular and other elongated shapes. Furthermore, the thickness of the monolithic semiconductor chip is not particularly limited, but is preferably around 5 to 100 μm, more preferably 10 to 45 μm. Based on LDBG, which uses lasers to create modified regions inside the wafer and utilizes the stress during wafer back-side grinding for wafer monolithicization, it is easy to manufacture the thickness of the monolithic semiconductor chip to be less than 50 μm, more preferably 10 to 45 μm. Furthermore, the size of the monolithic semiconductor chip is not particularly limited, but the chip size is preferably less than 600 mm. 2 More preferably less than 400mm 2 Further preferred size is less than 120mm 2 .

[0272] If the semiconductor processing protective sheet of the present invention is used, even for such a thin and / or small semiconductor chip, cracks can be prevented from forming on the semiconductor chip during back-side grinding (step 3) and during the removal of the semiconductor processing protective sheet (step 4).

[0273] (Step 4)

[0274] Next, a protective film for semiconductor processing is peeled off from the monolithized semiconductor wafer (i.e., multiple semiconductor chips). This process is performed, for example, by the following method.

[0275] First, when the adhesive layer of the semiconductor processing protective film is formed by an energy-curable adhesive, the adhesive layer is cured by irradiation with energy rays. Next, a pick-up tape is attached to the back side of the monolithized semiconductor wafer, and aligned in a pick-up manner. At this time, an annular frame disposed on the outer periphery of the wafer is also attached to the pick-up tape, fixing the outer periphery of the pick-up tape to the annular frame. The wafer and the annular frame can be attached to the pick-up tape simultaneously, or they can be attached at different times. Next, the semiconductor processing protective film is peeled off from the multiple semiconductor chips held on the pick-up tape.

[0276] Then, multiple semiconductor chips located on the pick-up tape are picked up and fixed onto a substrate or the like, thereby manufacturing a semiconductor device.

[0277] In addition, there are no special limitations on the pickup tape, for example, it can be composed of an adhesive sheet having a substrate and an adhesive layer disposed on one side of the substrate.

[0278] The above describes examples of the application of the semiconductor processing protective sheet of the present invention in methods for single-chip assembly of semiconductor wafers using DBG or LDBG. However, the semiconductor processing protective sheet of the present invention is preferably applied in LDBG, which can produce chipsets with smaller kerf widths and thinner wafers when single-chip assemblies of semiconductor wafers.

[0279] The embodiments of the present invention have been described above, but the present invention is not limited to any of the above embodiments and can be modified in various ways within the scope of the present invention.

[0280] Example

[0281] The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments.

[0282] The testing and evaluation methods in this embodiment are as follows.

[0283] (Loss tangent and energy storage modulus of the intermediate layer)

[0284] The intermediate layer described later is formed using a knife coater to form an intermediate layer with a thickness of 50 μm, on both sides of which are coated with a polyethylene terephthalate (PET) film release film (product name "SP-PET381031", thickness 38 μm, manufactured by LINTEC Corporation).

[0285] Prepare multiple intermediate layers formed in the above manner, peel off the PET release film, align the release surfaces with each other and stack them in sequence to create a laminate of intermediate layers (thickness of 1,000 μm).

[0286] Next, the resulting intermediate layer laminate is punched into a circle with a diameter of 10 mm to obtain a sample for testing viscoelasticity.

[0287] Using a viscoelasticity measuring apparatus (product name "ARES", manufactured by TA Instruments), the above sample was subjected to deformation at a frequency of 1 Hz, and the storage modulus (G') was measured from -30 to 120 °C at a heating rate of 10 °C / min. The loss tangent (tanδ) at 50 °C and the storage modulus (G') at 50 °C were calculated from the measured values. The calculated storage modulus value is set as storage modulus I.

[0288] (Loss tangent and storage modulus of adhesive layer)

[0289] Using the adhesive layer composition described later, an adhesive layer with a thickness of 50 μm is formed by applying a polyethylene terephthalate (PET) film-type release film (product name "SP-PET381031", thickness 38 μm, manufactured by LINTEC Corporation) to both sides using a blade coater.

[0290] Prepare multiple adhesive layers formed in the above manner, peel off the PET release film, align the release surfaces with each other and stack them in sequence to create a laminate of adhesive layers (1,000 μm thick).

[0291] Next, the resulting adhesive layer laminate is punched into a circle with a diameter of 10 mm to obtain a sample for testing viscoelasticity.

[0292] Using a viscoelasticity measuring apparatus (product name "ARES", manufactured by TA Instruments), the above sample was subjected to deformation at a frequency of 1 Hz, and the storage modulus was measured from -30 to 120 °C at a heating rate of 10 °C / min. The storage modulus (G') at 50 °C was calculated from the measured value. This value was set as the storage modulus A.

[0293] (DBG chip crack evaluation)

[0294] After trenches are formed on the surface of a 12-inch diameter silicon wafer, a semiconductor processing protective sheet manufactured in the examples and comparative examples is attached to the wafer surface. The wafer is then monolithically processed by grinding the back side, thereby monolithically processing the wafer into chips with a thickness of 50 μm and a chip size of 5 mm square by a pre-dicing method. Then, without removing the semiconductor processing protective sheet, the corners of the monolithically processed chips are observed from the ground surface of the wafer using a digital microscope (product name "VHX-1000", manufactured by KEYENCE CORPORATION) to observe whether each chip has cracks. The crack initiation rate of 700 chips is measured and evaluated according to the following evaluation criteria.

[0295] A: Less than 1.0%, B: 1.0–2.0%, C: Greater than 2.0%

[0296] (LDBG chip crack evaluation)

[0297] Using a back-grinding tape laminator (manufactured by LINTEC Corporation, device name "RAD-3510F / 12"), the semiconductor processing protective sheet manufactured in the examples and comparative examples was attached to a silicon wafer with a diameter of 12 inches and a thickness of 775 μm. A lattice-shaped modified region was formed on the wafer using a laser saw (manufactured by DISCO Corporation, device name "DFL7361"). The lattice size was 5 mm × 5 mm.

[0298] Next, a back-side grinding device (manufactured by DISCO Corporation, device name) was used.

[0299] The “DGP8761” is ground (including dry polishing) until the thickness is 50μm, thus converting the wafer into multiple chips.

[0300] After the polishing process, the semiconductor processing protective film is irradiated with energy rays (ultraviolet light). Cutting tape (manufactured by LINTEC Corporation, Adwill D-176) is then applied to the opposite side of the mounting surface of the protective film, and the protective film is peeled off. Then, using a digital microscope (product name "VHX-1000", manufactured by KEYENCE CORPORATION), the individual chips are observed. Chips with cracks are counted, and the crack initiation rate among 700 chips is determined and evaluated according to the following criteria.

[0301] A: Less than 1.0%, B: 1.0–2.0%, C: Greater than 2.0%

[0302] (Evaluation of incision adhesion)

[0303] The release tabs on the semiconductor processing protective sheets manufactured in the examples and comparative examples are peeled off, and the semiconductor processing protective sheets are placed on a tape laminator (manufactured by LINTEC Corporation, product name "RAD-3510") and attached to a 12-inch silicon wafer (760 μm thick) on which grooves are formed on the wafer surface by a pre-cutting method under the following conditions.

[0304] Roller height: 0mm, Roller temperature: 23℃ (room temperature), Worktable temperature: 23℃ (room temperature)

[0305] The silicon wafer with the obtained semiconductor processing protective film is single-chipped to a thickness of 50 μm and a square size of 5 mm by back-side grinding (pre-dicing method). The single-chip semiconductor processing protective film is mounted on a dicing tape applicator (manufactured by LINTEC Corporation, product name "RAD-2700"), and the adhesive is cured by irradiating it with ultraviolet light from the tape side (conditions: 230 mW / cm, 380 mJ / cm). Then, in the same RAD-2700 apparatus, a pick-up tape (manufactured by LINTEC Corporation, product name "D-510T") is attached from the chip side. At this time, the jig, called the ring frame, used in the pick-up process is also aligned and attached to the pick-up tape. Next, in the RAD-2700 apparatus, the cured semiconductor processing protective film is peeled off. Using a digital microscope (product name "VHX-1000", manufactured by KEYENCE CORPORATION), 700 chips after the protective film for semiconductor processing was removed were observed to confirm whether there was any residual adhesive near the cut. Those without residual adhesive were marked as ○, and those with residual adhesive were marked as ×.

[0306] (Evaluation of absorbency of convex dots)

[0307] Using a laminator (product name "RAD-3510F / 12", manufactured by LINTEC Corporation), a semiconductor processing protective sheet manufactured in the following examples and comparative examples was attached to a wafer (8-inch wafer, manufactured by WALTZ Corporation) with spherical bumps. The spherical bumps had a bump height of 80 μm, a spacing of 200 μm, and a diameter of 100 μm, and were made of Sn-3Ag-0.5Cu alloy. Furthermore, during attachment, the temperature of the lamination table and lamination rollers of the apparatus was set to 50°C.

[0308] After lamination, the diameter of the circular gaps around the bumps was measured from the substrate side using a digital optical microscope (product name "VHX-1000", manufactured by KEYENCE CORPORATION).

[0309] The smaller the diameter of the gap, the higher the bump absorption of the protective sheet used in semiconductor processing. The following criteria are used to determine the quality of bump absorption.

[0310] ○: The diameter of the pore is less than 150μm.

[0311] ×: The diameter of the pore is 150μm or more.

[0312] (Example 1)

[0313] (1) Substrate

[0314] Prepare a PET film (COSMOSHINE A4300 manufactured by TOYOBO CO.,LTD., thickness: 50μm, Young's modulus at 23℃: 2550MPa) with easy-to-adhere layers on both sides as the substrate.

[0315] (2) Buffer layer

[0316] (Synthesis of carbamate acrylate oligomers)

[0317] 2-hydroxyethyl acrylate is reacted with a terminal isocyanate urethane prepolymer to obtain a urethane acrylate oligomer (UA-2) with a weight average molecular weight (Mw) of about 9000. The terminal isocyanate urethane prepolymer is obtained by reacting a polyester diol with isophorone diisocyanate.

[0318] (Preparation of the composition for the buffer layer)

[0319] A composition for a buffer layer is prepared by incorporating 40 parts by weight of the above-synthesized urethane acrylate oligomer (UA-2), 20 parts by weight of isobornyl acrylate (IBXA), 20 parts by weight of tetrahydrofurfuryl acrylate (THFA), and 20 parts by weight of acrylmorpholine (ACMO), and further incorporating 2.0 parts by weight of 2-hydroxy-2-methyl-1-phenyl-propane-1-one (manufactured by BASF Japan Ltd, product name "IRGACURE1173") as a photopolymerization initiator.

[0320] (Manufacturing of a substrate with a buffer layer)

[0321] A buffer layer composition is applied to the release treatment surface of another release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031") to form a coating film. The coating film is then irradiated with ultraviolet light to semi-cur it, forming a buffer layer film with a thickness of 53 μm.

[0322] In addition, using a conveyor belt-type ultraviolet irradiation device (manufactured by EYE GRAPHICS Co., Ltd., device name "US2-0801") and a high-pressure mercury lamp (manufactured by EYE GRAPHICS Co., Ltd., device name "H08-L41"), the illuminance of light with a lamp height of 230mm, an output power of 80mW / cm, and a wavelength of 365nm was 90mW / cm. 2 The radiation dose is 50 mJ / cm. 2 Under the irradiation conditions described above, ultraviolet irradiation was carried out.

[0323] Next, the surface of the formed buffer layer film is bonded to the substrate, and ultraviolet light is irradiated again from the release liner side of the buffer layer film to completely cure the buffer layer film, forming a buffer layer with a thickness of 53 μm. Additionally, using the aforementioned ultraviolet irradiation device and high-pressure mercury lamp, the illuminance of light with a lamp height of 220 mm, a converted output power of 120 mW / cm, and a wavelength of 365 nm is 160 mW / cm². 2 The radiation dose was 650 mJ / cm. 2 Under the irradiation conditions described above, ultraviolet irradiation was carried out.

[0324] (3) Substrate A with intermediate layer

[0325] 91 parts by mass of n-butyl acrylate (BA) and 9 parts by mass of acrylic acid (AA) were copolymerized to obtain a non-energy-curable acrylic copolymer (a) (Mw: 600,000).

[0326] Unlike acrylic copolymers (a), 62 parts by mass of n-butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA) are copolymerized to obtain an acrylic polymer. 2-Methacryloxyethyl isocyanate (MOI) is then reacted with the acrylic polymer by adding 80 equivalents of the total hydroxyl groups (100 equivalents) of the acrylic polymer to obtain an energy-curable acrylic copolymer (b) (Mw: 100,000).

[0327] To 100 parts by weight of the non-energy-curable acrylic copolymer (a), 13 parts by weight of the energy-curable acrylic copolymer (b) were added, along with 2.79 parts by weight of an isocyanate crosslinking agent (manufactured by TOSOH, product name "CORONATE L") and 3.71 parts by weight of 1-hydroxycyclohexylphenyl ketone (manufactured by BASF, Irgacure 184) as a photopolymerization initiator. The solid content concentration was adjusted to 37% using toluene, and the mixture was stirred for 30 minutes to prepare the composition for the intermediate layer.

[0328] Next, the prepared intermediate layer solution is coated onto a PET release film (manufactured by LINTEC Corporation, SP-PET381031, 38 μm thick) and dried to form an intermediate layer with a thickness of 60 μm. This intermediate layer is then bonded to the side of the substrate with the buffer layer opposite to the side where the buffer layer is formed. The adhesive layer solution is then repeatedly coated onto the PET release film (manufactured by LINTEC Corporation, SP-PET381031, 38 μm thick), and this operation is repeated twice to form a substrate A with an intermediate layer and a thickness of 180 μm.

[0329] (4)Adhesive layer

[0330] (Preparation of the composition for the adhesive layer)

[0331] 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (2HEA) were copolymerized to obtain an acrylic polymer. 2-Methacryloxyethyl isocyanate (MOI) was then reacted with the acrylic polymer by adding 90 equivalents of the total hydroxyl groups (100 equivalents) of the acrylic polymer to obtain an energy-curable acrylic copolymer (c) (Mw: 500,000).

[0332] To 100 parts by mass of the energy-curable acrylic copolymer (c), 12 parts by mass of a multifunctional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, Shiko UT-4332), 1.1 parts by mass of an isocyanate crosslinking agent (manufactured by TOSOH CORPORATION, product name "CORONATEL"), and 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by BASF, Irgacure TPO) as a photopolymerization initiator were added, and the mixture was diluted with methyl ethyl ketone to prepare a coating liquid of an adhesive layer composition with a solid content concentration of 34% by mass.

[0333] (Manufacturing of protective wafers for semiconductor processing)

[0334] The above-mentioned adhesive layer composition is applied to the release surface of the release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031") and then heated and dried to form an adhesive layer with a thickness of 10 μm on the release sheet.

[0335] Then, an adhesive layer is laminated onto the surface of the substrate A with the intermediate layer to manufacture a protective sheet for semiconductor processing. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0336] (Example 2)

[0337] Except that the thickness of the intermediate layer is 120 μm, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0338] (Example 3)

[0339] Except for changing the amount of acrylic copolymer (b) in the intermediate layer composition to 34 parts by weight, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0340] (Example 4)

[0341] Except for changing the amount of acrylic copolymer (b) in the intermediate layer composition to 67 parts by weight, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0342] (Example 5)

[0343] Except for changing the amount of acrylic copolymer (b) in the intermediate layer composition to 100 parts by weight, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0344] (Example 6)

[0345] Except for the following two changes, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0346] (1) The thickness of the intermediate layer is 120 μm.

[0347] (2) As an adhesive layer composition, 60 parts by mass of 2-ethyl hydroxy acrylate (2EHA), 15 parts by mass of ethyl acrylate (EA), 5 parts by mass of methyl methacrylate (MMA), and 20 parts by mass of 2-hydroxyethyl acrylate (2HEA) are copolymerized to obtain an acrylic polymer. 2-Methacryloxyethyl isocyanate (MOI) is reacted with the acrylic polymer by adding 60 equivalents of the total hydroxyl groups (100 equivalents) of the acrylic polymer to obtain an energy-curable acrylic copolymer (d) (Mw: 500,000).

[0348] To 100 parts by weight of the energy-ray curable acrylic copolymer (d), 1.2 parts by weight of an isocyanate crosslinking agent (manufactured by TOSOH CORPORATION, product name "CORONATE L") and 7.29 parts by weight of 2,2-dimethoxy-2-phenylacetophenone (manufactured by BASF, Irgacure 651) as a photopolymerization initiator were added, and the mixture was diluted with toluene to prepare a coating liquid of an adhesive layer composition with a solid content concentration of 25% by weight.

[0349] (Example 7)

[0350] Except for the following changes, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0351] As an adhesive layer composition, 75 parts by weight of n-butyl acrylate (BA), 10 parts by weight of isobutyl acrylate (iBA), 5 parts by weight of methyl methacrylate (MMA), and 10 parts by weight of 4-hydroxybutyl acrylate (4HBA) are copolymerized to obtain an acrylic polymer. 2-Methacryloxyethyl isocyanate (MOI) is reacted with the acrylic polymer by adding 90 equivalents of the total hydroxyl groups (100 equivalents) of the acrylic polymer to obtain an energy-curable acrylic copolymer (e) (Mw: 500,000).

[0352] To 100 parts by weight of the energy-ray curable acrylic copolymer (e), 1.8 parts by weight of an isocyanate crosslinking agent (manufactured by TOSOH CORPORATION, product name "CORONATE L") and 7.29 parts by weight of 2,2-dimethoxy-2-phenylacetophenone (manufactured by BASF, Irgacure 651) as a photopolymerization initiator were added, and the mixture was diluted with toluene to prepare a coating liquid of an adhesive layer composition with a solid content concentration of 25% by weight.

[0353] (Example 8)

[0354] Except for changing the substrate with the buffer layer to a PET substrate, a protective sheet for semiconductor processing was obtained using the same method as in Example 2. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0355] (Comparative Example 1)

[0356] Except for changing the amount of acrylic copolymer (b) in the intermediate layer composition to 134 parts by weight, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0357] (Comparative Example 2)

[0358] Except that the adhesive layer composition of Example 6 was used as the adhesive layer composition, a protective sheet for semiconductor processing was obtained by the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0359] (Comparative Example 3)

[0360] Except for using a substrate D with an intermediate layer manufactured as described below, and using the adhesive layer composition of Example 6 as the adhesive layer composition, a protective sheet for semiconductor processing was obtained using the same method as in Example 1. The types of substrates, the composition and thickness of the intermediate layer and the adhesive layer are shown in Table 1.

[0361] Substrate D with intermediate layer

[0362] The UV-curable resin composition was prepared by mixing 40 parts by weight of monofunctional urethane acrylate (solid content ratio), 45 parts by weight of isobornyl acrylate (IBXA) (solid content ratio), 15 parts by weight of hydroxypropyl acrylate (HPA) (solid content ratio), 3.5 parts by weight of pentaerythritol tetrakis(3-mercaptobutyric acid) (product name "KARENZ MT PE1", SHOWA DENKO KK, tetrafunctional secondary thiol compound, solid content concentration 100 parts by weight), 1.8 parts by weight of UV reactive thermal crosslinking agent, and 1.0 part by weight of 2-hydroxy-2-methyl-1-phenyl-propane-1-one (product name "Darocur 1173", manufactured by BASF, solid content concentration 100 parts by weight) as a photopolymerization initiator. The mixture was then sprayed into a fountain. The coating is applied to a polyethylene terephthalate (PET) film-type release liner (manufactured by LINTEC Corporation, SP-PET381031, 38μm thick) with a cured thickness of 400μm using a die-on method. Ultraviolet light is then irradiated from the coating side to form a semi-cured layer.

[0363] In addition, a conveyor belt-type ultraviolet irradiation device (product name "ECS-401GX", manufactured by EYE GRAPHICS Co., Ltd.) was used as the ultraviolet irradiation device, and a high-pressure mercury lamp (H04-L41, manufactured by EYE GRAPHICS Co., Ltd.) was used as the ultraviolet source. Under the irradiation conditions, the illuminance of light at a wavelength of 365nm was 112mW / cm². 2 The light intensity is 177 mJ / cm² 2 Under conditions of ultraviolet irradiation (measured by “UVPF-A1” manufactured by EYE GRAPHICS Co.,Ltd.).

[0364] A polyethylene terephthalate (PET) film (Lumirror 75U403, 75 μm thick, manufactured by TORAY INDUSTRIES, INC.) was laminated onto the formed semi-cured layer, and ultraviolet light was further irradiated from the PET film side (using the aforementioned ultraviolet irradiation device and ultraviolet source, with an irradiation condition of 271 mW / cm²). 2The light intensity is 1200 mJ / cm² 2 This process allows the material to fully cure, forming a 400μm thick intermediate layer on the PET film of the substrate.

[0365] [Table 1]

[0366]

[0367] The obtained samples (Examples 1-8 and Comparative Examples 1-3) were subjected to the above-described measurements and evaluations. The results are shown in Table 2.

[0368] [Table 2]

[0369]

[0370] As can be confirmed from Table 2, when the loss tangent of the AI ​​ratio and the intermediate layer is within the above range, even when the wafer with unevenness is monolithized by DBG and LDBG, the unevenness can be fully embedded, the crack generation rate caused by chip displacement is low, and no nick residue is observed.

Claims

1. A protective sheet for semiconductor processing, having a substrate and having an intermediate layer and an adhesive layer sequentially on a main surface of the substrate, and satisfying the following (a) and (b): (a) The loss tangent of the intermediate layer at 50°C, measured at a frequency of 1 Hz, is greater than 0.40 and less than 0.

65. (b) The ratio of the storage modulus A of the adhesive layer to the storage modulus I of the intermediate layer, measured at 50°C at a frequency of 1 Hz, [A / I] is 0.80 or more and 3.50 or less. The intermediate layer is composed of a composition containing an acrylic polymer (A) with a weight-average molecular weight of 300,000 to 1,500,000 and an energy-curable acrylic polymer (B) with a weight-average molecular weight of 50,000 to 250,000.

2. The protective sheet for semiconductor processing according to claim 1, wherein, A buffer layer is provided on another main surface of the substrate.

3. The protective sheet for semiconductor processing according to claim 1 or 2, wherein, The Young's modulus of the substrate is above 1000 MPa.

4. The protective sheet for semiconductor processing according to claim 1 or 2, wherein, The thickness of the intermediate layer is between 60 μm and 250 μm.

5. The protective sheet for semiconductor processing according to claim 1 or 2, wherein, The adhesive layer is energy-cured by radiation.

6. The protective sheet for semiconductor processing according to claim 1 or 2, wherein, The intermediate layer is cured by energy rays.

7. The protective sheet for semiconductor processing according to claim 1 or 2, wherein, In the process of grinding the back side of a semiconductor wafer with trenches formed on its surface and then grinding the semiconductor wafer to produce individual semiconductor chips, a semiconductor processing protective sheet is attached to the surface of the semiconductor wafer for use.

8. A method for manufacturing a semiconductor device, comprising: The process of attaching a protective sheet for semiconductor processing according to any one of claims 1 to 7 to the surface of a semiconductor wafer having uneven surfaces; The process of forming trenches from the surface side of the semiconductor wafer, or the process of forming a modified region inside the semiconductor wafer from the surface or back side of the semiconductor wafer; A process of grinding a semiconductor wafer with the semiconductor processing protective film attached to its surface and the trenches or modified regions formed therein, starting from the back side, to convert the wafer into multiple chips from the trenches or modified regions. and The process of peeling the protective sheet for semiconductor processing from a single semiconductor chip.

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