Workpiece processing adhesive tape and back surface polishing method for workpieces

Abstract

The technical problem of the present application is to provide a workpiece processing adhesive tape which is substantially single-layer, can inhibit the generation of wrinkles, and can stably adhere to a workpiece. The means for solving the technical problem is that according to the present application, a workpiece processing adhesive tape (10) which is substantially single-layer can be provided, wherein the indentation depth D1 of the first surface (12) is 3 μm or more, and the indentation depth D2 of the second surface (14) is 1.5 μm or less.

Description

Technical Field

[0001] This invention relates to a workpiece processing tape. More particularly, it relates to a workpiece processing tape used to temporarily protect the workpiece surface and hold the workpiece during back-side grinding and other processing of various workpieces such as semiconductor wafers. Furthermore, this invention relates to a back-side grinding method for a workpiece using this workpiece processing tape. Background Technology

[0002] Semiconductor chips and other chips with circuits formed on them are obtained by isolating workpieces such as wafers, which have multiple circuits formed on them, into individual workpieces. With the rapid advancement of miniaturization and multifunctionality of electronic devices equipped with such chips, there are also demands for miniaturization, low backlighting, and high density of the chips. In order to miniaturize and reduce the backlighting of the chips, circuits are usually formed on the surface of the workpiece, and then the back of the workpiece is ground to reduce the thickness of the chip.

[0003] When grinding the back side of a workpiece, a workpiece processing tape called back grinding tape is attached to the workpiece surface. It is used to temporarily protect the circuitry on the workpiece surface and hold the workpiece in place.

[0004] As a tape for processing such workpieces, an adhesive tape consisting of a substrate film and an adhesive layer is used. In addition, when the workpiece has protruding electrodes such as bumps on its surface, in order to absorb the height difference of the protruding electrodes and maintain the workpiece flat, a soft intermediate layer is sometimes sandwiched between the substrate film and the adhesive layer.

[0005] In order to hold the workpiece in place and facilitate its removal after processing, energy-curable adhesives are sometimes used in the adhesive layer of workpiece processing tapes. These energy-curable adhesives hold the workpiece with sufficient adhesion before being irradiated with energy rays; upon irradiation, they polymerize and cure, reducing adhesion and making the workpiece easier to remove from the adhesive layer. Furthermore, energy-curable compositions are sometimes used as intermediate layers.

[0006] However, because the adhesive strength of the adhesive layer or intermediate layer decreases due to the irradiation of energy rays, the adhesion between the substrate film and the adhesive layer, between the intermediate layer and the adhesive layer, and between the substrate film and the intermediate layer decreases. When the workpiece is removed, the adhesive layer or intermediate layer may sometimes transfer to the workpiece.

[0007] To eliminate this undesirable situation, Patent Document 1 (Japanese Patent Application Publication No. 2013-23665) discloses an "adhesive sheet formed by sequentially layering a substrate film, an anchor coating containing a compound having energy-ray polymerizable groups, and an energy-ray curable adhesive layer." Both the anchor coating and the adhesive layer are in an uncured state (unirradiated by energy rays). After a specified processing step, energy ray irradiation is performed, and the workpiece is removed from the adhesive sheet. During the curing of the energy-ray curable adhesive, at least a portion of the energy-ray polymerizable groups contained in the anchor coating also polymerize, forming covalent bonds between a portion of the adhesive layer and the anchor coating. The adhesive layer and the substrate are thus bonded tightly via the anchor coating. As a result, even after the energy-ray curable adhesive has cured, the adhesion between the substrate film and the adhesive layer is maintained, preventing the adhesive layer from transferring to the workpiece.

[0008] However, in the adhesive sheet of Patent Document 1, the addition of an anchor coating increases the number of processing steps and raises the product price due to increased raw material costs. Furthermore, because it has a multi-layered structure, the possibility of the adhesive layer transferring to the workpiece due to interlayer peeling cannot be completely eliminated.

[0009] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2013-23665 Summary of the Invention

[0010] (a) Technical problems to be solved Therefore, the inventors of this application have researched how to retain and protect workpieces using adhesive tapes that are essentially single-layer adhesive layers without any substrate or intermediate layer. However, with conventional workpiece processing tapes, when used as a single-layer adhesive layer without any substrate, the adhesion of the adhesive layer can cause problems during the process. Therefore, designing the adhesive layer to be rigid is considered, but the workpiece retention performance can easily become insufficient. As a countermeasure, designing the adhesive layer to be soft is considered, but wrinkles can easily form on the workpiece processing tape when it is applied to the workpiece. When applying the tape, tension is applied to the tape and it is slightly stretched to prevent air from entering the adhesion surface. If the tape is soft, the stretching of the tape can sometimes become uneven, resulting in wrinkles. If wrinkles form on the workpiece processing tape, the adhesion between the tape and the workpiece becomes uneven, and proper adhesion may not be possible. In this situation, the tape needs to be peeled off and reapplied, which reduces operational efficiency.

[0011] The present invention was made in view of the following situation, and its object is to provide a workpiece processing tape that is essentially a single layer and can stably attach to the workpiece, suppressing the formation of wrinkles.

[0012] (II) Technical Solution The solution of the present invention is as follows.

[0013] (1) A workpiece processing tape, which is basically a single layer, wherein the indentation depth D1 of the first side, as measured by the following method, is 3 μm or more, and the indentation depth D2 of the second side is 1.5 μm or less. The method for determining the indentation depth is as follows: The measuring device is a dynamic ultramicro surface hardness tester. The indenter is a 115-degree triangular cone indenter with a Poisson's ratio of 0.07. The load speed is 0.015 mN / s. The indentation pressure starts from 0 mN, and the indentation depth is measured when the indentation pressure reaches 0.3 mN.

[0014] (2) The workpiece processing tape according to (1), wherein D1 / D2 is 2.05 or more.

[0015] (3) The workpiece processing tape according to (1), wherein D1-D2 is 1.6μm or more.

[0016] (4) The workpiece processing tape according to (1), wherein the adhesion of the first surface to the silicon wafer at 23°C is 1000mN / 25mm or more, and the adhesion of the second surface to the silicon wafer at 23°C is 600mN / 25mm or less.

[0017] (5) The workpiece processing tape according to (1) has a thickness of 90 μm or more.

[0018] (6) The workpiece processing tape according to (1) contains an energy-curing component and an ultraviolet absorber.

[0019] (7) A method for grinding the back side of a workpiece, comprising the following steps: The process of attaching the first side of the workpiece processing tape as described in any one of (1) to (6) to the surface of the workpiece; The process of grinding the back side of a workpiece to which the workpiece processing tape is attached; and The process of peeling the workpiece processing tape off the workpiece after it has been ground from the back.

[0020] (III) Beneficial Effects According to the present invention, it is possible to provide a workpiece processing tape that, although it is essentially a single layer, can still suppress wrinkles during stretching and stably adhere to the workpiece. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the adhesive tape used for workpiece processing in this embodiment.

[0022] Figure 2 This is a cross-sectional schematic diagram illustrating an example of the manufacturing process of the workpiece processing tape according to this embodiment.

[0023] Figure 3 This is a cross-sectional schematic diagram showing the application of workpiece processing tape to the circuit surface of a wafer.

[0024] Explanation of reference numerals in the attached figures 10: Adhesive tape for workpiece processing; 10a: Uncured adhesive layer; 12: First surface (surface not irradiated by energy rays); 14: Second surface (surface irradiated by energy rays); 16: First release film; 20: Workpiece (wafer); 20a: Surface of workpiece (circuit surface of wafer); EB: Energy rays. Detailed Implementation

[0025] The present invention will now 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.

[0026] The workpiece refers to a plate-shaped body that has been coated with the workpiece processing tape of this embodiment and has undergone back-side grinding or other processing in that state. Examples of workpieces include circular wafers (including those with orientation planes) and square strips (elongated substrates) that have undergone panel-level packaging and molding resin sealing. Examples of wafers include semiconductor wafers such as silicon wafers, gallium arsenide wafers, silicon carbide wafers, gallium nitride wafers, and indium phosphide wafers, or insulator wafers such as glass wafers, lithium tantalate wafers, and lithium niobate wafers. In addition, it can also be a reconstructed wafer composed of resin and semiconductors for making fan-out packages, etc.

[0027] The "surface" of a workpiece refers to the surface where circuits, electrodes, etc., are formed, while the "back side" of a workpiece refers to the surface where circuits, etc., are not formed. As an electrode, it can be a convex electrode such as a bump.

[0028] The processing of a workpiece refers to the process of grinding the back side of the workpiece, simplifying the workpiece into individual pieces, marking the back side of the workpiece using a laser marking machine, or forming circuits or protruding electrodes on the surface side of the workpiece. From the perspective of easily obtaining the effects of the present invention, the processing of the workpiece is more preferably the process of grinding the back side of the workpiece.

[0029] "(Meth)acrylate" is used to refer to both "acrylate" and "methacrylate", and other similar terms are used in the same way.

[0030] "Energy rays" refer to ultraviolet rays, electron beams, etc., with ultraviolet rays being preferred.

[0031] Unless otherwise specified, "weight-average molecular weight" refers to the converted value of polystyrene determined by gel permeation chromatography (GPC). This determination is based on methods such as using a high-speed GPC apparatus, the "HLC-8120GPC" manufactured by TOSOH CORPORATION, sequentially connected to a high-speed chromatographic column, the "TSK guard column H". XL -H”, TSK Gel GMH XL "TSK Gel G2000H" XL The apparatus (all of which are manufactured by TOSOH CORPORATION) was used with a differential refractive index meter as a detector at a column temperature of 40°C and a delivery rate of 1.0 mL / min.

[0032] A release film is a film that supports an adhesive layer and a surface coating in a peelable manner. The film is not limited in thickness and is used in the concept of a sheet.

[0033] The mass ratios in the descriptions of compositions such as tape-forming compositions are calculated based on the active ingredient (solid component), and solvents are not included unless otherwise specified.

[0034] Next, the structure of the workpiece processing tape of the present invention will be described in detail. Furthermore, hereafter, the workpiece processing tape of the present invention will sometimes be referred to simply as "tape".

[0035] (10 pieces of tape for workpiece processing) like Figure 1 As shown, the workpiece processing tape 10 of this embodiment is composed of a basically single-layer adhesive having a first side 12 and a second side 14 with different surface hardness.

[0036] "Essentially a single layer" means that there is no clear boundary surface when observing the cross-section. It also means that in the cross-section of the workpiece processing tape 10, the color and brightness are uniform across the entire cross-section, or the color and brightness change slowly from the first side to the second side without showing abrupt changes.

[0037] Furthermore, "consisting of an adhesive that is essentially a single layer" means that it does not have other layers with functions related to the retention and protection of the workpiece, but this does not preclude the presence of layers unrelated to the retention and protection of the workpiece. For example, in order to prevent dirt from adhering to the first surface 12 before using the workpiece processing tape 10, a release film can be laminated on the first surface 12.

[0038] The workpiece processing tape 10 of this embodiment has a first surface 12 and a second surface 14 with different surface hardness. The "surface hardness" is evaluated by the indentation depth measured using the method described below.

[0039] The indentation depth was determined by using a dynamic ultramicro surface hardness tester as the measuring device. At 23°C, the indenter (115-degree triangular cone indenter (Poisson's ratio: 0.07)) was pressed into the surface of the tape 10 with a load speed of 0.015 mN / s starting from a pressure of 0 mN, and the indentation depth was measured when the indentation pressure reached 0.3 mN.

[0040] In this embodiment, the indentation depth D1 of the first surface 12 of the workpiece processing tape 10, as measured by the above method, is 3 μm or more, preferably 3.1 μm or more, and more preferably 3.2 μm or more. By keeping the indentation depth D1 of the first surface 12 within the above range, the first surface 12 has appropriate softness and excellent adhesion to the workpiece surface. There is no particular upper limit to the indentation depth D1 of the first surface 12, but if it is excessively soft, operability may decrease. Therefore, the indentation depth D1 is preferably 5.0 μm or less, and more preferably 4.2 μm or less.

[0041] In this embodiment, the indentation depth D2 of the second surface 14 of the workpiece processing tape 10, as measured by the above method, is 1.5 μm or less, preferably 1.4 μm or less, and more preferably 1.3 μm or less. By ensuring that the indentation depth D2 of the second surface 14 is within the above range, the second surface 14 has appropriate rigidity, maintaining the shape of the workpiece processing tape 10. Even when tension is applied to the workpiece surface when attached to the workpiece, wrinkles on the tape can be prevented. The lower limit of the indentation depth D2 of the second surface 14 is not particularly limited, but excessive rigidity can sometimes reduce operability. Therefore, the indentation depth D2 is preferably 0.8 μm or more, and more preferably 1.0 μm or more.

[0042] In the workpiece processing tape 10 of this embodiment, it is preferable that the indentation depth D1 of the first surface 12 and the indentation depth D2 of the second surface 14 have a sufficient difference. That is, the ratio (D1 / D2) of the indentation depth D1 of the first surface 12 to the indentation depth D2 of the second surface 14 is preferably 2.05 or more, and more preferably 2.15 or more. There is no particular upper limit to the ratio (D1 / D2), but if D1 is large and the first surface is too soft, or if D2 is small and the second surface is too hard, the aforementioned undesirable situation may sometimes occur. Therefore, the ratio (D1 / D2) is preferably 5.00 or less, and more preferably 3.50 or less.

[0043] Furthermore, the difference (D1-D2) between the indentation depth D1 of the first surface 12 and the indentation depth D2 of the second surface 14 is preferably 1.6 μm or more, and more preferably 1.7 μm or more. There is no particular upper limit to the difference (D1-D2), but for the same reasons as the ratio (D1 / D2), the difference (D1-D2) is preferably 4.2 μm or less, and more preferably 3.5 μm or less.

[0044] As described above, the workpiece processing tape 10 of this embodiment is composed of a first side 12 with a softer surface and a second side 14 with a harder surface. The first side 12 is softer and adheres closely to the surface of the workpiece to be adhered to. The second side 14 is harder and has the function of preventing adhesion to the worktable or the like and suppressing wrinkles that may occur during stretching.

[0045] The first 12 pairs of workpieces, which are the adhered objects, exhibit high adhesion. For example, the adhesion force to the silicon wafer is preferably 1000 mN / 25 mm or more, and more preferably 1500 mN / 25 mm or more. By keeping the adhesion force within the above range, the workpiece can be stably held during back-side grinding and other processing, and the surface can be reliably protected. Furthermore, the aforementioned adhesion force refers to the adhesion force to the mirror-treated surface of the smoothed mirror-treated silicon wafer, and is specifically measured using the method described below.

[0046] Adhesion was measured according to JIS Z 0237. Specifically, at 23°C and 50% relative humidity, a strip of workpiece processing tape 10, cut to a width of 25 mm, was attached to the mirror-treated surface of a mirror-treated silicon wafer using a 2 kg roller. After 20 minutes, the peeling force at a speed of 300 mm / min in a 90° direction was measured using an adhesion-coating peeling analysis device. The silicon wafer used was a mirror-treated silicon wafer with a surface roughness Ra smoothed to 5 nm ± 2 nm. The workpiece processing tape was attached to either the first side or the second side (described later) of the mirror-treated surface, and the adhesion was measured.

[0047] There is no particular limit to the upper limit of the adhesion force of the first surface 12 to the silicon wafer. However, when the adhesion force of the first surface 12 is too high, the first surface becomes excessively soft, and sometimes the operability decreases. Therefore, the adhesion force of the first surface 12 to the silicon wafer is preferably below 6000mN / 25mm, and more preferably below 5000mN / 25mm.

[0048] The second surface 14 is relatively hard and preferably has low adhesion so that it does not adhere to the worktable or similar surfaces. For example, the adhesion to the silicon wafer is preferably 600 mN / 25 mm or less, and more preferably 500 mN / 25 mm or less. There is no particular limitation on the lower limit of the adhesion of the second surface 14 to the silicon wafer. When the adhesion of the second surface 14 is too low, the second surface becomes excessively hard, and sometimes the operability decreases. Therefore, the adhesion of the second surface 14 to the silicon wafer is preferably 50 mN / 25 mm or more, and more preferably 80 mN / 25 mm or more.

[0049] The thickness of the workpiece processing tape 10 in this embodiment is preferably 90 μm or more, more preferably 115 μm or more, and even more preferably 135 μm or more. By keeping the thickness within the above range, the difference in surface hardness between the first and second surfaces can be easily achieved, and the workpiece can be held more reliably. The upper limit of the thickness of the workpiece processing tape 10 in this embodiment is not particularly limited, but if the thickness is too thick, it will cause in-layer damage during peeling, and the adhesive will easily remain on the workpiece surface. Therefore, the thickness is preferably 300 μm or less, and even more preferably 200 μm or less.

[0050] (Composition of the workpiece processing tape 10) The composition of the workpiece processing tape 10 is not particularly limited as long as it has a first side 12 and a second side 14 with different surface hardness. The following description of the composition of the workpiece processing tape 10 of the present invention is based on non-limiting examples.

[0051] The workpiece processing tape 10 is preferably a partially cured material formed by curing one of the two main surfaces (the second surface) of a planar adhesive layer in a manner that makes one surface (the first surface) harder than the other surface (the second surface).

[0052] (Composition for adhesives) The adhesive composition constituting the workpiece processing tape 10 preferably includes an energy-curing component and an ultraviolet absorber. The adhesive composition containing an energy-curing compound as an energy-curing component is cured by irradiation with energy rays. Flowability, tackiness, and tensile strength decrease due to curing. By including an ultraviolet absorber, although the surface irradiated by energy rays (the second surface) cures, the energy rays are absorbed by the ultraviolet absorber as they pass through the adhesive composition layer, thus the amount of energy rays reaching the other surface (the first surface) easily attenuates to a low level. As a result, the adhesive composition on the first surface is either uncured or only slightly cured. Therefore, by including both the energy-curing component and the ultraviolet absorber, it is easy to form a first surface and a second surface with a difference in hardness.

[0053] From the perspective of properly controlling the curing of the second side, the adhesive composition containing an energy-curable compound preferably contains urethane (meth)acrylate (d1), and more preferably contains an energy-curable compound (d3) having an alicyclic or heterocyclic group having 6 to 20 cyclic atoms. Furthermore, it may also contain a multifunctional energy-curable compound (d2) and / or an energy-curable compound (d4) having functional groups. In addition to the above-mentioned components, the adhesive composition may also contain an energy-curable compound (d5) other than components (d1) to (d4), and a photopolymerization initiator. Furthermore, from the perspective of inhibiting the curing of the first side, the adhesive composition preferably contains an ultraviolet absorber. Furthermore, without impairing the effects of the present invention, the adhesive composition may also contain other additives.

[0054] The following is a detailed description of the components contained in the adhesive composition containing an energy-curable compound.

[0055] (Carbamate (meth)acrylate (d1)) 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.

[0056] 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 is preferably monofunctional or difunctional.

[0057] Component (d1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer with a (meth)acrylate having hydroxyl groups, wherein the terminal isocyanate urethane prepolymer is obtained by reacting a polyol compound with a polyisocyanate compound. Furthermore, two or more components (d1) can be used alone or in combination.

[0058] 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 one of difunctional diols, trifunctional triols, or polyols with more than four functionalities, but is preferably a difunctional diol, and more preferably a polyolefin diol.

[0059] 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, and ω,ω'-diisocyanate dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, phenyldimethylmethylene diisocyanate, bitoluidine diisocyanate, tetramethylphenyldimethylmethylene diisocyanate, and naphthalene-1,5-diisocyanate.

[0060] Among these polyisocyanate compounds, isophorone diisocyanate, hexamethylene diisocyanate, and phenyl diisocyanate are preferred.

[0061] A urethane (meth)acrylate (d1) can be obtained by reacting a terminal isocyanate urethane prepolymer with a hydroxyl-containing (meth)acrylate, wherein the terminal isocyanate urethane prepolymer is obtained by reacting the aforementioned polyol compound with a polyisocyanate compound. The hydroxyl-containing (meth)acrylate is not particularly limited as long as it is a compound having both a hydroxyl group and a (meth)acryloyl group in at least one molecule.

[0062] 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-phenyloxypropyl (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 reactants obtained by reacting (meth)acrylate with vinyl alcohol, vinylphenol, or diglycidyl esters of bisphenol A.

[0063] Among these hydroxyl-containing (meth)acrylates, hydroxyalkyl (meth)acrylates are preferred, and 2-hydroxyethyl (meth)acrylates are more preferred.

[0064] 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.

[0065] The content of component (d1) in the adhesive composition is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 65% by mass, relative to the total amount (100% by mass) of the adhesive composition.

[0066] (Multifunctional Energy Ray Curing Compound (d2)) A multifunctional energy-curable compound refers to a compound other than component (d1) that has two or more energy-curable unsaturated groups. These energy-curable unsaturated groups are functional groups containing carbon-carbon double bonds, such as (meth)acryloyl, vinyl, allyl, and vinylbenzyl. Two or more energy-curable unsaturated groups can be combined. A three-dimensional network structure (cross-linked structure) is formed by the reaction of the energy-curable unsaturated groups in the multifunctional energy-curable compound with the (meth)acryloyl group in component (d1), or by the reaction of the energy-curable unsaturated groups in component (d2) with each other. Compared to compounds containing only one energy-curable unsaturated group, using a multifunctional energy-curable compound results in a greater cross-linked structure formed by energy irradiation, making it easier to cure the second side and more effective at relieving stress during back-side grinding.

[0067] Furthermore, if there is overlap between the definition of component (d2) and the definitions of component (d3) or component (d4) described later, the overlapping portion is considered to be 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 energy-curable unsaturated groups is included in the definitions of both component (d2) and component (d3), but in this invention, such a compound is considered to be included in component (d2). Similarly, a compound having functional groups such as hydroxyl, epoxy, amide, or amino groups and having two or more energy-curable unsaturated groups is included in the definitions of both component (d2) and component (d4), but in this invention, such a compound is considered to be included in component (d2).

[0068] From the above perspective, the number of energy-curable unsaturated groups (number of functional groups) in a multifunctional energy-curable compound is preferably 2 to 10, more preferably 3 to 6.

[0069] 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.

[0070] Specific components (d2) 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.

[0071] In addition, component (d2) can be used alone or in combination of two or more. Among these components, dipentaerythritol hexa(meth)acrylate is preferred.

[0072] The content of component (d2) in the adhesive composition is preferably 0 to 40% by mass, more preferably 0.5 to 20% by mass, and even more preferably 0 to 15% by mass, relative to the total amount (100% by mass) of the adhesive composition.

[0073] (Energy-curable compounds with alicyclic or heterocyclic groups having 6 to 20 cyclic atoms (d3)) Component (d3) is an energy-curable compound other than component (d1) that has an alicyclic or heterocyclic group having 6 to 20 cyclic atoms. More preferably, it is a compound having one (meth)acryloyl group. By using component (d3), the film-forming properties of the obtained adhesive composition can be improved.

[0074] Furthermore, the definition of component (d3) overlaps with the definition of component (d4) described later, but the overlapping portion is included in component (d4). For example, compounds having at least one (meth)acryloyl group, an alicyclic or heterocyclic group with 6 to 20 cyclic atoms, and functional groups such as hydroxyl, epoxy, amide, and amino groups are included in the definitions of both component (d3) and component (d4), but in this invention, such compounds are considered to be included in component (d4).

[0075] Specific components (d3) include, for example, isobornyl methacrylate, dicyclopentenyl methacrylate, dicyclopentyl methacrylate, dicyclopentenyloxy methacrylate, cyclohexyl methacrylate, adamantane methacrylate, and other methacrylates containing alicyclic groups; and tetrahydrofurfuryl methacrylate, morpholine methacrylate, and other methacrylates containing heterocyclic groups.

[0076] In addition, two or more components (d3) can be used alone or in combination.

[0077] Among (meth)acrylates containing alicyclic groups, isobornyl (meth)acrylate is preferred, and among (meth)acrylates containing heterocyclic groups, tetrahydrofurfuryl (meth)acrylate is preferred.

[0078] The content of component (d3) in the adhesive composition is preferably 10 to 60% by mass, more preferably 20 to 55% by mass, and even more preferably 25 to 50% by mass, relative to the total amount (100% by mass) of the adhesive composition.

[0079] (Energy-curing compounds with functional groups (d4)) Component (d4) is an energy-curable compound other than component (d1) containing functional groups such as hydroxyl, epoxy, amide, and amino groups. More preferably, it is a compound having at least one (meth)acryloyl group, and more preferably, it is a compound having one (meth)acryloyl group.

[0080] Component (d4) and component (d1) have good compatibility, making it easy to adjust the viscosity of the adhesive composition within a suitable range. Furthermore, even when the adhesive layer is made thin, the cushioning properties are easily improved, and by adjusting the polarity of the adhesive layer through the introduction of functional groups, the adhesion of the first and second sides of the workpiece processing tape can be easily adjusted to the aforementioned range.

[0081] Examples of components (d4) include hydroxyl-containing (meth)acrylates, epoxy-containing compounds, amide-containing compounds, and amino-containing (meth)acrylates. Among these components, hydroxyl-containing (meth)acrylates are preferred.

[0082] 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 (meth)acrylate.

[0083] Furthermore, component (d4) can be used alone or in combination of two or more. In order to improve the film-forming properties of the adhesive composition and to adjust the polarity of the adhesive layer, the content of component (d4) in the adhesive composition is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 10% by mass, relative to the total amount (100% by mass) of the adhesive composition.

[0084] (Energy-curing compounds other than components (d1)~(d4) (d5)) Without impairing the effects of the present invention, the adhesive composition may contain a monofunctional energy-curable compound (d5) other than the components (d1) to (d4) described above.

[0085] Examples of ingredients (d5) include alkyl (meth)acrylates having alkyl groups having 1 to 20 carbon atoms; vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylpyrrolidone, and N-vinylcaprolactam. Furthermore, ingredients (d5) can be used alone or in combination of two or more.

[0086] The content of component (d5) in the adhesive composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, further preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass, relative to the total amount (100% by mass) of the adhesive composition.

[0087] (UV absorber) The ultraviolet absorber is a compound that absorbs in the wavelength region of energy rays irradiating the second surface of the adhesive composition described above. Preferably, the ultraviolet absorber has an absorption peak in the wavelength region of 280-380 nm. Examples of ultraviolet absorbers are not particularly limited, but include triazine compounds, benzophenone compounds, benzotriazole compounds, benzoate compounds, benzoxazinone compounds, phenyl salicylate compounds, cyanoacrylate compounds, nickel complex salt compounds, etc. These compounds can be used alone or in combination with two or more. Among the above compounds, triazine compounds, benzophenone compounds, or benzotriazole compounds are preferred, and triazine compounds are particularly preferred.

[0088] Examples of triazine compounds include 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine and 2-[4,6-bis(2,4-dimethylyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol.

[0089] Examples of benzophenone compounds include 2,2-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, and 2-hydroxy-4-n-octyloxybenzophenone.

[0090] Examples of benzotriazole compounds include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole, octyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate, and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate.

[0091] The content of ultraviolet absorber in the adhesive composition is preferably 0.05 to 5% by mass, more preferably 0.1 to 2.5% by mass, and particularly preferably 0.3 to 1% by mass, relative to the total amount (100% by mass) of the adhesive composition. Therefore, even if the second side of the workpiece processing tape 10 is irradiated with sufficiently curable ultraviolet light, the amount of ultraviolet light reaching the first side will be attenuated to a low level. As a result, the adhesive composition on the first side is either not cured or only slightly cured. Therefore, by including an energy-curing component and an ultraviolet absorber, it is easy to form a first side and a second side with a difference in hardness.

[0092] (Photopolymerization initiator) From the perspective of shortening the polymerization time based on energy ray irradiation and reducing the amount of energy ray irradiation when curing the second side, it is preferable that the adhesive composition further contains a photopolymerization initiator.

[0093] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, dicene compounds, thioxanone compounds, peroxides, and photosensitizers such as amines or quinones. More specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloroanthraquinone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0094] These photopolymerization initiators can be used alone or in combination of two or more.

[0095] The content of photopolymerization initiator in the adhesive composition is preferably 0.05 to 15 parts by mass relative to the total amount (100 parts by mass), more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass.

[0096] (Other additives) Without impairing the effects of the present invention, the adhesive composition may 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 adhesive composition is preferably 0.01 to 6 parts by weight, more preferably 0.1 to 3 parts by weight, relative to the total amount (100 parts by weight) of the adhesive composition.

[0097] In the workpiece processing tape 10 formed from an adhesive composition comprising an energy-curable compound and an ultraviolet absorber, the second side is preferably obtained by polymerizing and curing the adhesive composition by irradiating it with energy rays. That is, the second side is preferably a substance obtained by curing the adhesive composition. The adhesive composition of the first side is uncured or slightly cured, which maintains sufficient adhesion to the workpiece and protects the surface.

[0098] Therefore, the adhesive layer preferably contains repeating units from component (d1), and more preferably further contains repeating units from component (d3). Furthermore, the adhesive layer may contain repeating units from component (d2) and / or repeating units from component (d4), and may also contain repeating units from component (d5). The proportion of each repeating unit in the adhesive layer is generally consistent with the ratio (feed ratio) of the components constituting the adhesive composition.

[0099] (Manufacturing method of adhesive tape for workpiece processing) Next, an example of a method for manufacturing the workpiece processing tape 10 will be described, but the workpiece processing tape 10 of the present invention is not limited to being obtained by the method described below.

[0100] like Figure 2 As shown in (a), an uncured adhesive layer 10a is formed on the first release film 16. The adhesive layer 10a is preferably formed by the adhesive composition described above.

[0101] The release film is a release film for which at least one side has been subjected to a release treatment. Specifically, examples include release films made by coating a release agent on the surface of a substrate for release films.

[0102] As the substrate for the release film, 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; and polyolefin resins such as polypropylene resin and polyethylene resin. Examples of release agents include silicone-based release agents, alkyd-based release agents, and fluorinated release agents.

[0103] The thickness of the release film is not particularly limited, but is preferably 10~200μm, more preferably 20~150μm.

[0104] The method for forming the adhesive layer 10a on the first release film 16 is not particularly limited. It is acceptable to apply the adhesive composition or a coating agent prepared by diluting the adhesive composition with an organic solvent using known methods such as spin coating, spray coating, bar coating, doctor blade coating, roller coating, scraper coating, mold coating, or gravure coating. Regarding the coating thickness of the adhesive layer 10a, it is acceptable to apply it in such a way that the final thickness after ultraviolet irradiation is the same as the thickness of the workpiece processing tape 10, and then dry it as needed. The adhesive composition can be diluted with an organic solvent as needed and applied as a coating agent. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. Furthermore, the adhesive composition or its coating agent can be applied in one coat or in two or more coats. When applying the adhesive composition more than twice, use an adhesive composition with the same composition.

[0105] Next, as Figure 2 As shown in (b), a second release film 18 is laminated on the adhesive layer 10a. The same film as the first release film described above is used as the second release film.

[0106] Furthermore, such as Figure 2 As shown in (c), any one side of the adhesive layer 10a is irradiated with an energy beam EB, causing the energy beam curing component contained in the irradiated side of the adhesive layer 10a to cure, forming a cured second side. The energy beam irradiation is performed, for example, using a high-pressure mercury lamp. Ultraviolet light is preferred as the energy beam. At this time, the adhesive composition on the opposite side (first side) of the irradiated side is uncured or slightly cured, maintaining sufficient adhesion to the workpiece and protecting the surface.

[0107] The illuminance and intensity of the energy-based EB (extracorporeal membrane oxygenation) ray only need to be sufficient to ensure the second surface cures and the first surface maintains adhesion. These parameters vary depending on the type and amount of the energy-based curing components and the type and amount of the ultraviolet absorber, and cannot be uniformly specified. However, the preferred illuminance is 30~400 mW / cm². 2 The optimal light intensity is 200~1500 mJ / cm². 2 The irradiation by energy rays can be performed in two or more stages.

[0108] After the above processes, a workpiece processing tape 10 is obtained, which is held between the first release film 16 and the second release film 18. Then, the second release film 18 can be peeled off and removed as needed. The workpiece processing tape 10 held between the first release film 16 and the second release film 18, and the workpiece processing tape 10 with the first release film 16 stacked on top, can be wound into a roll as a long strip of tape and transported or stored as a roll. Furthermore, the first release film 16 only needs to be peeled off before the process of attaching it to the surface of the workpiece.

[0109] (Control of surface hardness on the first and second surfaces) According to the manufacturing method described above, a workpiece processing tape having a first side and a second side with different surface hardness can be obtained. In particular, by using an adhesive composition containing an ultraviolet absorber, it is easy to obtain a workpiece processing tape having a first side and a second side with different surface hardness.

[0110] The second side 14 of the adhesive tape 10 used for workpiece processing has a high surface hardness, while the first side 12 has a low surface hardness. This difference in surface hardness can be verified by the difference in the polymerization rate of the energy-curable component before and after irradiation with energy rays. That is, the polymerization rate of the energy-curable component on the second side 14 is high before and after irradiation with energy rays, while that on the first side is low.

[0111] The polymerization rate of an energy-curable component before and after irradiation with energy rays can be estimated based on the decrease rate of polymeric groups contained in the energy-curable component. For example, the polymerization rate can be estimated by measuring the absorption peak intensity of characteristic polymeric groups contained in the energy-curable component, as determined by infrared absorption spectrometry, before and after irradiation with energy rays.

[0112] Specifically, the reaction rate can be estimated using the following formula. The "peak intensity" referred to below means the absorption peak intensity of the characteristic polymeric groups contained in the aforementioned energy-curable component.

[0113] [Mathematical Expression 1]

[0114] In a preferred embodiment, the ratio of the polymerization rate of the first side to the polymerization rate of the second side (first side / second side) is 0.99 or less, more preferably 0.97 or less. There is no particular limitation on the lower limit of this ratio, but if the polymerization rate of the first side is too low (resulting in excessive softness) or the polymerization rate of the second side is too high (resulting in excessive hardness), the operability of the workpiece processing tape 10 may decrease. Therefore, the polymerization rate ratio (first side / second side) is preferably 0.80 or more, more preferably 0.85 or more.

[0115] When the second side is not sufficiently cured, simply increasing its polymerization rate is sufficient. Conversely, when the first side is over-cured and loses its adhesiveness, simply decreasing its polymerization rate is sufficient. More specifically, when the second side is not sufficiently cured, increasing the amount of photopolymerization initiator or increasing the irradiance and intensity of the irradiated energy rays is sufficient. When the first side is over-cured and loses its adhesiveness, increasing the amount of ultraviolet absorber or decreasing the irradiance and intensity of the irradiated energy rays is sufficient. Furthermore, the surface hardness of the first and second sides can also be adjusted by modifying the blending of energy-curing compounds in the adhesive composition.

[0116] (Workpiece machining methods) The workpiece processing tape of the present invention is used to temporarily protect the surface of and hold the workpiece during back-side grinding and other processing of various workpieces such as semiconductor wafers. Preferably, the workpiece processing tape of the present invention is used to protect the surface of the workpiece by attaching it to the workpiece surface during back-side grinding.

[0117] As a non-limiting example of the use of tape for workpiece processing, a back-grinding method for workpieces in which the workpiece is a wafer and the processing includes back-grinding will be further described in detail.

[0118] Specifically, the back-side grinding method for a workpiece (wafer) includes at least the following steps 1 to 3.

[0119] Step 1: The process of attaching the above-mentioned workpiece processing tape to the surface of the wafer. Step 2: Grinding the wafer with workpiece processing tape attached to its surface from the back side. Step 3: The process of peeling the workpiece processing tape off the wafer after back-side grinding. The following is a detailed description of each step in the above-mentioned wafer back-side polishing method.

[0120] (Process 1) like Figure 3 As shown, in step 1, the first side 12 of the workpiece processing tape 10 of this embodiment is attached to the surface 20a of the wafer 20, which serves as the workpiece. By attaching the workpiece processing tape to the surface of the wafer, the surface of the wafer can be adequately protected. After attachment, if the workpiece processing tape 10 is larger than the surface size of the wafer 20, it can be cut or removed along the outer periphery of the wafer as needed using a blade.

[0121] The thickness of the wafer before grinding is not particularly limited, typically around 500~1000μm. Furthermore, circuitry is usually formed on the surface of the wafer. Forming circuitry on the wafer surface can be achieved using various methods, including conventional methods such as etching and lift-off.

[0122] A wafer with workpiece processing tape attached is placed on an adsorption stage (an example of an operating table), where it is adsorbed and held on the stage. At this time, the second side 14 of the workpiece processing tape is positioned on the adsorption stage side and adsorbed.

[0123] (Process 2) After step 1, the back side of the wafer on the adsorption stage is ground to obtain a back-ground wafer. In this embodiment, the thickness of the back-ground wafer is not particularly limited; for example, it can be less than 200 μm or less than 100 μm. When the thickness of the back-ground wafer is within the above range, chip miniaturization and low back-ground reduction can be easily achieved.

[0124] (Process 3) Next, the workpiece processing tape 10 is peeled off from the wafer. The method for peeling off the workpiece processing tape 10 is not particularly limited. For example, dicing tape or dicing-die bonding tape, or other tapes, can be attached to the back side of the wafer after back-side grinding. The workpiece processing tape 10 is peeled off from the wafer, which is held on other tapes. The peeling of the workpiece processing tape 10 is performed by pressing the peeling tape, which serves as the peeling starting point, onto the second side 14 of the workpiece processing tape, pulling the peeling tape in the folding direction, and peeling off the workpiece processing tape 10.

[0125] The workpiece processing tape of this embodiment has the above-mentioned characteristics. Therefore, although it is basically a single-layer workpiece processing tape, it still has sufficient adhesion in holding and protecting the wafer, suppresses wrinkles during stretching, and can stably attach the workpiece.

[0126] Furthermore, the workpiece processing tape of the present invention is also suitable for use in the manufacturing method of single-chip products using a pre-cutting method.

[0127] In the chip manufacturing method using the pre-cutting method, in addition to the above-mentioned steps 1 to 3, the following step (step 4) is included: forming a groove from the surface side of the wafer, or forming a modified region inside the wafer from the surface or back side of the wafer.

[0128] When forming modified regions on a wafer, it is preferable to perform step 1 before step 4. On the other hand, when forming grooves on the wafer surface by cutting or the like, step 1 is performed after step 4. That is, in step 1, workpiece processing tape is attached to the surface of the wafer having grooves formed in step 4, which will be described later.

[0129] In step 4, grooves are formed from the surface side of the wafer. Alternatively, modified regions are formed inside the wafer from either the surface or back side.

[0130] The grooves formed in this process are shallower than the thickness of the wafer. The grooves can be formed by cutting using conventionally known wafer dicing equipment. These grooves are formed along the starting point of the groove individualization process in step 2 described above through back-side grinding.

[0131] Furthermore, the modified region is the brittle portion of the wafer. It is formed by thinning the wafer and applying force during the grinding process, thereby destroying the modified region and creating the starting point for single-chip assembly. That is, the grooves and modified regions in process 4 are formed along the dividing lines when the wafer is single-chip assembled in process 2.

[0132] The modified region is formed by irradiating the interior of the wafer with a laser focused on the wafer. The laser irradiation can be performed from either the surface or the back side of the wafer. Alternatively, in one embodiment of the modified region formation, when step 4 is performed after step 1 and the wafer surface is irradiated with laser, the laser is applied to the wafer through a workpiece processing tape.

[0133] In the pre-cutting process, the back-side grinding of step 2 is performed as follows: when a groove is formed on the wafer, the wafer is thinned to at least the bottom of the groove. Through this back-side grinding, the groove is formed as a cut through the wafer, and the wafer is monolithized through the cut.

[0134] On the other hand, when the modified region is formed, the grinding surface (back side of the wafer) can reach the modified region through grinding, or it can reach the modified region less strictly. That is, as long as it is ground close to the modified region, the wafer can be broken and monolithized starting from the modified region. The workpiece processing tape can be peeled off from the monolithized wafer (i.e., chip) in the same way as in step 3 above.

[0135] 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 forms within the scope of the present invention.

[0136] Example The invention will now be described in more detail using examples, but the invention is not limited to these examples.

[0137] The measurement and evaluation methods in this embodiment are as follows.

[0138] (Indentation depths D1, D2) Under the following conditions, an indenter was pressed into the non-irradiated surface (first surface) and irradiated surface (second surface) of the prepared workpiece processing tape using energy rays, respectively, and the indentation depth was measured. The indentation depth was measured using a dynamic ultra-micro surface hardness tester. At 23°C, the indenter (115-degree triangular cone indenter (Poisson's ratio: 0.07)) was pressed into the surface of the tape 10 with a load speed of 0.015 mN / s starting from a pressure of 0 mN, and the indentation depth was measured when the indentation pressure reached 0.3 mN.

[0139] (Adhesion) Adhesion was measured according to JIS Z 0237. Specifically, at 23°C and 50% relative humidity, a strip of workpiece processing tape 10, cut to a width of 25 mm, was attached to the mirror-treated surface of a mirror-treated silicon wafer using a 2 kg roller. After 20 minutes, the peeling force at a speed of 300 mm / min in a 90° direction was taken as the adhesion force using an adhesion-coating peel analysis apparatus (manufactured by Kyowa InterfaceScience Co., Ltd., VPA-2). A mirror-treated silicon wafer with a surface roughness Ra smoothed to 5 nm ± 2 nm was used. Workpiece processing tape was attached to the mirror-treated surface, and the adhesion was measured. The measurement length was set to 70 mm, and the initial 10 mm and the final 10 mm portion of the measurement value were removed from the effective value. Then, the average value of this measurement is taken as the adhesion force (mN / 25mm), and the adhesion force is measured twice as described above, and the average value is used. The adhesion force is measured on the non-irradiated surface (first surface) and irradiated surface (second surface) of the energy rays of the workpiece processing tape prepared below.

[0140] (Polymerization rate) The polymerization rate of the energy-curable component before and after irradiation with energy rays is determined by the decrease rate of the polymerizable groups contained in the energy-curable component.

[0141] Specifically, for the adhesive layer before irradiation with energy rays, and the first and second sides of the workpiece processing tape after irradiation with energy rays, the absorption peak intensity of the characteristic polymeric groups contained in the curable components of the energy rays and the peak intensity of the bonds that do not participate in the curing reaction are measured by infrared absorption analysis.

[0142] As a peak that does not participate in the curing reaction, a wavenumber of 775 cm⁻¹ was used. -1 The peak values ​​were processed, and the data processing standardized the three IR measurement results of the adhesive layer before irradiation with energy rays, the first side and the second side of the workpiece processing tape after irradiation with energy rays.

[0143] Next, based on the absorption peak from the characteristic polymeric groups involved in energy-ray curing in the three standardized measurement results (810 cm⁻¹ in the examples and comparative examples of this application), -1 The polymerization rates of the first and second sides are calculated using the following formulas based on the peak intensity of the adhesive layer before irradiation with energy rays, the peak intensity of the first side of the adhesive tape used for workpiece processing, and the peak intensity of the second side. Then, the ratio of the polymerization rate of the first side to the polymerization rate of the second side (first side / second side) is calculated.

[0144] The term "peak intensity" as used below refers to the absorption peak intensity of the characteristic polymeric groups contained in the energy-curable component.

[0145] [Mathematical Expression 2]

[0146] (Applicability of tape to workpiece) Using a tape application apparatus (RAD-3510F / 12) manufactured by LINTEC Corporation, the uncured side (first side) of a workpiece processing tape was applied to a mirror-finished silicon wafer (a mirror-finished wafer with a surface roughness Ra smoothed to 5nm ± 2nm). Application was performed at room temperature (23°C) at a speed of 20mm / second. The condition of the applied tape was visually inspected and evaluated according to the following criteria.

[0147] <<Judgment Criteria>> Judgment A: No wrinkles were formed on the tape.

[0148] • Judgment B: Wrinkles have appeared on the tape.

[0149] (The adhesion of the tape to the workpiece) Using a tape application apparatus (RAD-3510F / 12) manufactured by LINTEC Corporation, the uncured side (first side) of the workpiece processing tape was applied to a mirror-finished silicon wafer (a mirror-finished wafer with a surface roughness Ra smoothed to 5nm ± 2nm). Application was performed at room temperature (23°C) at a speed of 20mm / second. Using a blade included with the application apparatus, the workpiece processing tape was cut along the outer periphery of the silicon wafer. The adhesion between the tape and the silicon wafer at the outer periphery was visually inspected and evaluated according to the following criteria.

[0150] <<Judgment Criteria>> Judgment A: No gaps were created between the tape and the silicon wafer.

[0151] • Judgment B: A gap has been created between the tape and the silicon wafer.

[0152] (Preparation of urethane acrylate oligomer (component (d1))) As components of the adhesive composition, three difunctional urethane acrylate oligomers (UA-1, UA-2, and UA-3) were prepared. The urethane acrylate oligomers were obtained by reacting 2-hydroxyethyl acrylate (HEA) with urethane prepolymers, wherein the urethane prepolymers were either urethane prepolymers with isocyanates terminal from isophorone diisocyanate obtained by reacting polypropylene glycol (PPG) as described in Table 1 with isophorone diisocyanate (IPDI), or urethane prepolymers with isocyanates terminal from hexamethylene diisocyanate obtained by reacting PPG with hexamethylene diisocyanate (HMDI). The monomer composition (molar ratio) of each urethane acrylate oligomer is shown in the table below.

[0153] [Table 1] (Preparation of adhesive composition) The above-synthesized urethane acrylate oligomers, the acrylic monomers listed in the table below, and 2-hydroxy-2-methyl-1-phenyl-1-propanone (manufactured by IGMresins, product name "Omnirad 1173") as photopolymerization initiator and triazine UV absorber (manufactured by BASF, product name "Tinuvin 400") as UV absorber were blended in the weight ratios specified in the table below to prepare adhesive compositions for manufacturing the workpiece processing tapes of Examples 1-3 and Comparative Examples 1-2.

[0154] [Table 2] (Manufacturing of adhesive tape for workpiece processing) The workpiece processing tapes of Examples 1-3 and Comparative Examples 1-2 were manufactured using the following method.

[0155] like Figure 2 As shown in (a), the adhesive composition is applied to the peeled surface of the first release film 16 (manufactured by LINTEC Corporation, product name "SP-PET381031", silicone-peeled polyethylene terephthalate (PET) film, thickness: 38 μm) to form an uncured (i.e., uncured before irradiation with energy rays) adhesive layer 10a.

[0156] Next, as Figure 2As shown in (b), a second release film 18 (manufactured by LINTEC Corporation, product name "SP-PET381031") is laminated on an uncured adhesive layer 10a.

[0157] Next, as Figure 2 As shown in (c), ultraviolet light (irradiance (346 mW / cm²)) is applied from the second release film 18 side at the light intensity shown in Table 2. 2 The adhesive layer 10a is irradiated, causing the energy-curing components contained in the irradiated surface to cure, forming a cured surface (second surface). At this time, the adhesive composition on the opposite side (first surface) of the irradiated surface is uncured or slightly cured. The thickness of the tape used for processing each workpiece is set to 150 μm.

[0158] The penetration depth, adhesion, and polymerization rate ratio of the energy-irradiated surface (second surface) and the non-irradiated surface (first surface) of each workpiece processing tape obtained above were measured to evaluate the tape's applicability and adhesion. The results are shown in Table 3. Furthermore, in the workpiece processing tape of Comparative Example 1, the tape's adhesion was insufficient (wrinkles occurred), therefore, the tape's adhesion could not be evaluated (denoted as F in Table 3).

[0159] [Table 3] Industrial applicability As shown in Table 3, although the workpiece processing tape of the present invention is basically a single-layer workpiece processing tape, it still suppresses wrinkles when stretched and can stably attach the workpiece.

Claims

1. A workpiece processing tape, which is essentially a single layer, wherein, The indentation depth D1 of the first surface, as determined by the following method, is 3 μm or more, and the indentation depth D2 of the second surface is 1.5 μm or less. The method for determining the indentation depth is as follows: The measuring device is a dynamic ultramicro surface hardness tester. The indenter is a 115-degree triangular pyramid indenter with a Poisson's ratio of 0.

07. The load speed is 0.015 mN / s. The indentation pressure starts from 0 mN, and the indentation depth is measured when the indentation pressure reaches 0.3 mN.

2. The workpiece processing tape according to claim 1, wherein, D1 / D2 is greater than 2.

05.

3. The adhesive tape for workpiece processing according to claim 1, wherein, D1-D2 is greater than 1.6μm.

4. The adhesive tape for workpiece processing according to claim 1, wherein, The adhesion of the first surface to the silicon wafer at 23°C is above 1000mN / 25mm, and the adhesion of the second surface to the silicon wafer at 23°C is below 600mN / 25mm.

5. The workpiece processing tape according to claim 1, wherein the thickness is 90 μm or more.

6. The workpiece processing tape according to claim 1, comprising an energy-curing component and an ultraviolet absorber.

7. A method for grinding the back side of a workpiece, comprising the following steps: The process of attaching the first side of the workpiece processing tape according to any one of claims 1 to 6 to the surface of the workpiece; The process of grinding the back side of a workpiece to which the workpiece processing tape is attached; and The process of peeling the workpiece processing tape off the workpiece after it has been ground from the back.

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