Adhesive tape

Abstract

To provide an adhesive tape which sufficiently lowers adhesive force accompanied by irradiation with ultraviolet rays even after heating, and can maintain such characteristics as to prevent adhesion of a component contained in an adhesive layer from being attached to a member such as a semiconductor element.SOLUTION: An adhesive tape includes a base material, and an adhesive layer laminated on one surface of the base material, and is used for temporarily fixing a substrate, wherein the adhesive layer contains a double bond introduction type acrylic resin (A) having an unsaturated double bond in its side chain, and a photopolymerization initiator (B) having a molecular weight of 300 or more and 2,000 or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape used for temporarily fixing substrates. [Background technology]

[0002] In the manufacturing process of semiconductor devices, adhesive tape (dicing tape) is used to temporarily fix semiconductor substrates.

[0003] For example, Patent Document 1 discloses a semiconductor processing sheet (adhesive tape) that includes a substrate and an adhesive layer laminated on the substrate. This semiconductor processing sheet is used so that the adhesive layer adheres tightly to the TSV wafer or TSV chip. This allows the TSV wafer or the like to be temporarily fixed.

[0004] The adhesive layer is composed of an adhesive formed from an adhesive composition containing a (meth)acrylic acid ester copolymer (A) having an energy ray-curable group introduced into its side chain. The (meth)acrylic acid ester copolymer (A) is disclosed to be obtained by reacting an acrylic copolymer (AP) obtained by copolymerizing methyl (meth)acrylate (A1) and a functional group-containing monomer (A2) having a reactive functional group with a curable group-containing compound (A3) having a substituent reactive with the functional group of the functional group-containing monomer (A2) and an energy ray-curable carbon-carbon double bond.

[0005] Patent Document 1 also discloses that parameters P1 and P2 related to component AP each satisfy specific conditions. Parameter P1 is the mass ratio of the structure derived from component A1 in component AP, and when this parameter satisfies specific conditions, a pressure-sensitive adhesive layer having resistance to low-polarity organic solvents is obtained. Parameter P2 is the product of the mass ratio of the structure derived from component A1 in component AP and the gel fraction of the pressure-sensitive adhesive, and when this parameter satisfies specific conditions, a pressure-sensitive adhesive layer having embeddability for microprotrusions is obtained.

[0006] In the semiconductor device manufacturing process, the outer periphery of the adhesive layer of the semiconductor processing sheet is first fixed with a ring frame, and then the backside of a semiconductor substrate such as a TSV wafer is attached to the adhesive layer. Next, the semiconductor substrate is cut across its thickness using a dicing saw to separate it into individual pieces. Next, the adhesive layer is irradiated with ultraviolet light to harden it, thereby reducing its adhesive strength. Next, the semiconductor processing sheet is stretched radially, and the resulting semiconductor elements are picked up.

[0007] It is also being considered to subject the semiconductor elements obtained by singulation to a heat resistance test before picking them up. In this case, not only the semiconductor elements but also the semiconductor processing sheet are subjected to the heat resistance test and heated. The heated semiconductor processing sheet is then irradiated with ultraviolet light. For this reason, the adhesive layer of the semiconductor processing sheet must maintain the property of reducing adhesive strength with ultraviolet light irradiation even after heating.

[0008] However, conventional adhesive tapes have a problem in that they do not maintain the above-mentioned properties sufficiently after heating. If the adhesive strength does not decrease sufficiently, there is a concern that pickup failure may occur or that components of the adhesive layer may adhere to the semiconductor element. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-073056 Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to provide an adhesive tape whose adhesive strength is sufficiently reduced upon irradiation with ultraviolet light even after heating, and which maintains the property that components contained in the adhesive layer do not easily adhere to components such as semiconductor elements. [Means for solving the problem]

[0011] These objects can be achieved by the present invention as set forth in (1) to (4) below. (1) An adhesive tape comprising a base material and an adhesive layer laminated on one surface of the base material, the adhesive tape being used to temporarily fix a substrate, The adhesive layer is a double bond-introduced acrylic resin (A) having an unsaturated double bond in a side chain; a photopolymerization initiator (B) having a molecular weight of 300 or more and 2,000 or less; An adhesive tape comprising:

[0012] (2) The pressure-sensitive adhesive tape according to (1), wherein the photopolymerization initiator (B) contains an α-hydroxyketone-based photopolymerization initiator.

[0013] (3) The pressure-sensitive adhesive tape according to (1) or (2), wherein the photopolymerization initiator (B) exhibits a weight loss rate of 20.0% or less after being heated in the atmosphere at a temperature of 150°C for 1 hour.

[0014] (4) The pressure-sensitive adhesive tape according to (1) or (2), wherein the blending ratio of the photopolymerization initiator (B) to 100 parts by mass of the double bond-introduced acrylic resin (A) is 0.1 parts by mass or more and 20 parts by mass or less. [Effects of the Invention]

[0015] According to the present invention, an adhesive tape can be obtained that, even after heating, sufficiently reduces adhesive strength upon irradiation with ultraviolet light and maintains the property of preventing components contained in the adhesive layer from adhering to the tape. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing an example of a semiconductor device manufactured using an adhesive tape according to an embodiment. [Figure 2] 1A to 1C are longitudinal cross-sectional views illustrating a method for manufacturing a semiconductor device using the adhesive tape according to the embodiment. [Figure 3]1A to 1C are longitudinal cross-sectional views illustrating a method for manufacturing a semiconductor device using the adhesive tape according to the embodiment. [Figure 4] 1A to 1C are longitudinal cross-sectional views illustrating a method for manufacturing a semiconductor device using the adhesive tape according to the embodiment. [Figure 5] 1 is a longitudinal cross-sectional view showing a pressure-sensitive adhesive tape according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressure-sensitive adhesive tape according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0018] 1. Semiconductor Devices First, prior to describing the adhesive tape according to the embodiment, an example of a semiconductor device manufactured using the adhesive tape will be described.

[0019] 1 is a longitudinal cross-sectional view showing an example of a semiconductor device 10 manufactured using an adhesive tape according to an embodiment. In the following description, the upper side in FIG. 1 is referred to as "top" and the lower side as "bottom." In addition, in each drawing of the present application, the dimensional ratios in the left-right direction and the thickness direction may differ from the actual ratios.

[0020] The semiconductor device 10 shown in Figure 1 has a semiconductor chip 20 (semiconductor element), an interposer 30 (substrate) that supports the semiconductor chip 20, a plurality of conductive bumps 70 (terminals), and a molded portion 17 (sealing portion) that seals the semiconductor chip 20.

[0021] The interposer 30 is an insulating substrate and is made of various resin materials such as polyimide, epoxy resin, cyanate resin, bismaleimide triazine resin (BT resin), etc. The planar shape of the interposer 30 can be, for example, a quadrilateral such as a square or a rectangle.

[0022] On the upper surface of the interposer 30, terminals 41 made of a conductive metal material such as copper are provided in a predetermined shape.

[0023] Furthermore, a plurality of vias (through holes) and through wiring (not shown) are formed in the interposer 30 so as to penetrate the interposer 30 in the thickness direction.

[0024] Each bump 70 protrudes from the lower surface of the interposer 30. Each bump 70 is electrically connected to a terminal 41 via a through-wiring. Such a bump 70 is mainly made of a brazing material such as solder, silver brazing, copper brazing, or phosphorus copper brazing.

[0025] Terminals 41 provided on the interposer 30 are electrically connected to terminals 21 of the semiconductor chip 20 via connecting portions 81 .

[0026] An underfill material is filled in the gap between the semiconductor chip 20 and the interposer 30. The hardened underfill material forms a sealing layer 80. This sealing layer 80 improves the bonding strength between the semiconductor chip 20 and the interposer 30 and prevents the intrusion of foreign matter, moisture, and the like into the gap.

[0027] A molded portion 17 is provided on the upper side of the interposer 30 so as to cover the semiconductor chip 20 and the interposer 30. The molded portion 17 is made of a hardened semiconductor sealing material (sealant). By providing the molded portion 17, the semiconductor chip 20 is sealed, and the intrusion of foreign matter, moisture, etc. into the semiconductor chip 20 is prevented.

[0028] 1, the semiconductor chip 20 (semiconductor element) has a semiconductor chip body 23 (semiconductor element body) and terminals 21 provided on the lower surface of the semiconductor chip body 23. A circuit (not shown) is formed on the upper surface of the semiconductor chip body 23. Examples of materials that can be used to form the semiconductor chip body 23 include semiconductor materials such as Si, SiC, GaN, and Ga2O3.

[0029] 2. Manufacturing method of semiconductor device Next, an example of a method for manufacturing the semiconductor device 10 using the adhesive tape according to the embodiment will be described.

[0030] 2 to 4 are vertical cross-sectional views illustrating a method for manufacturing a semiconductor device 10 using the adhesive tape 100 according to the embodiment. In the following description, the upper side in each figure will be referred to as "upper" and the lower side will be referred to as "lower."

[0031] [1A] First, a semiconductor substrate 7 (semiconductor wafer) with a protective tape 500 attached thereto is prepared, as shown in Figure 2(a). The protective tape 500 is attached to a surface 71 of the semiconductor substrate 7, and protects a circuit formation region (not shown) included in the surface 71 from each of the processes described below. The circuit formation region (not shown) includes multiple individual circuits, and is divided into multiple regions in the processes described below.

[0032] [2A] Next, the upper surface of the protective tape 500 is fixed to a chuck table 600 of a back grinding device (back grinder). Then, the back surface 72 of the semiconductor substrate 7 shown in FIG. 2(b) is ground (back-grinded). This makes it possible to thin the semiconductor substrate 7. The thickness of the semiconductor substrate 7 after back-grinding is not particularly limited, but is, for example, about 40 to 600 μm.

[0033] [3A] Next, an adhesive tape 100 is prepared. The adhesive tape 100 shown in FIG. 2(c) has a base material 4 and an adhesive layer 2 laminated on the base material 4. Next, as shown in FIG. 2(c), an outer periphery 121 of the adhesive layer 2 of the adhesive tape 100 is fixed with a wafer ring 9. Then, the back surface 72 of a semiconductor substrate 7 (semiconductor wafer) is attached to a central portion 122 of the adhesive layer 2.

[0034] [4A] Next, as shown in Fig. 2(d), the protective tape 500 is peeled off. By peeling off the protective tape 500, the surface 71 of the semiconductor substrate 7 is exposed.

[0035] [5A] Next, as shown in FIG. 3(a), the adhesive tape 100 to which the semiconductor substrate 7 is attached is placed on a dicer table 200.

[0036] [6A] Next, the semiconductor substrate 7 is cut into individual pieces using a dicing saw (blade) not shown (dicing process). As a result, a plurality of semiconductor chips 20 are obtained on the adhesive tape 100, as shown in FIG. 3(b). At this time, the adhesive tape 100 has a cushioning effect, so that cracks, chips, etc. in the semiconductor substrate 7 can be prevented. Furthermore, it is preferable that the cut marks made by the dicing saw reach the base material 4, as shown in FIG. 3(b). This allows the semiconductor substrate 7 to be reliably cut into individual pieces.

[0037] If necessary, cutting may be performed while supplying water to the semiconductor substrate 7. This makes it possible to prevent scattering of dust and overheating of the semiconductor substrate 7 that occurs when cutting the semiconductor substrate 7.

[0038] [7A] Next, a reliability test is performed on the semiconductor chips 20 obtained by the dicing process while they are still fixed to the adhesive tape 100. The reliability test may include a temperature cycle test, a high-temperature storage test, a high-temperature reverse bias test, a high-temperature and high-humidity reverse bias test, a thermal shock test, etc. All of these tests are types of heat resistance tests performed while applying heat H to the semiconductor chips 20, as shown in FIG. 3(c). For this reason, the adhesive tape 100 is required to maintain the adhesive strength necessary to fix the semiconductor chips 20 even at high temperatures. By performing the reliability test while the semiconductor chips 20 are fixed to the adhesive tape 100 in this way, the number of work steps associated with transporting the semiconductor chips 20 can be reduced compared to when the reliability test is performed after the pick-up process.

[0039] [8A] Next, as shown in FIG. 3(d), the adhesive tape 100 is irradiated with energy rays E such as ultraviolet rays (energy ray irradiation process). In the adhesive tape 100 irradiated with the energy rays E, the adhesive strength of the adhesive layer 2 is reduced. This allows the semiconductor chip 20 to be easily picked up in the pick-up process described later.

[0040] [9A] Next, the adhesive tape 100 with the semiconductor substrate 7 attached thereto is placed on an expanding table 300. The expanding table 300 includes an expanding stage 310 corresponding to the center of the semiconductor substrate 7 and a holder 320 corresponding to the outer periphery of the semiconductor substrate 7. In the pick-up process, as shown in FIG. 4(a), the expanding stage 310 is pushed upward against the holder 320 of the expanding table 300. This causes the adhesive tape 100 to be stretched radially, and gaps are formed between the semiconductor chips 20 obtained by singulation (expanding process).

[0041] [10A] Next, the adhesive tape 100 to which the expanding semiconductor substrate 7 has been attached is placed on a pickup table 400. Then, as shown in FIG. 4(b), the semiconductor chip 20 is picked up by a suction tool (not shown) such as a vacuum collet or air tweezers (pickup process). In the pick-up process, the semiconductor chip 20 may be pushed up from below by a needle (not shown). Furthermore, the adhesive tape 100 maintains the adhesive strength reduction capability due to the energy ray irradiation treatment even after the heat resistance test. Therefore, in the pick-up treatment, the adhesive strength of the adhesive tape 100 is sufficiently reduced, allowing the semiconductor chip 20 to be smoothly picked up. In addition, the occurrence of problems such as components contained in the adhesive layer 2 adhering to the semiconductor chip 20 can be suppressed.

[0042] By going through the above steps [1A] to [10A], the individual semiconductor chips 20 are obtained. The individual semiconductor chips 20 are placed on, for example, the interposer 30 shown in FIG. 1. Then, the sealing layer 80 and the molded part 17 are provided. In this way, the semiconductor device 10 shown in FIG. 1 is obtained.

[0043] 3. Adhesive tape Fig. 5 is a vertical cross-sectional view showing an adhesive tape 100 according to an embodiment. In the following description, the upper side in Fig. 5 will be referred to as "top" and the lower side as "bottom."

[0044] The adhesive tape 100 is an adhesive tape used to temporarily fix a semiconductor substrate 7 (substrate), and as shown in FIG. 5, comprises a base material 4 and an adhesive layer 2. The adhesive layer 2 is laminated on the upper surface (one surface) of the base material 4. The adhesive layer 2 contains a double bond-introduced acrylic resin (A) and a photopolymerization initiator (B). The double bond-introduced acrylic resin (A) is an acrylic resin having an unsaturated double bond in its side chain, and provides adhesiveness to the adhesive layer 2. The photopolymerization initiator (B) facilitates the initiation of polymerization of the double bond-introduced acrylic resin (A). The molecular weight of the photopolymerization initiator (B) is 300 or more and 2,000 or less.

[0045] With this configuration, even after a heat resistance test, the adhesive strength of the adhesive tape 100 can be sufficiently reduced by the energy ray irradiation treatment. This allows the pickup treatment to be carried out smoothly. Furthermore, the occurrence of problems such as components contained in the adhesive layer 2 adhering to the semiconductor chip 20 can be suppressed.

[0046] Furthermore, with the above-described configuration, since the adhesive tape 100 has good heat resistance, a reliability test involving heating can be performed on a plurality of semiconductor chips 20 while they are fixed to the adhesive tape 100. This eliminates the need to transport the semiconductor chips 20 individually, as was conventionally the case, and reduces the number of steps required for the reliability test, thereby improving the manufacturing efficiency of the semiconductor device 10. Each part of the adhesive tape 100 will be described in detail below.

[0047] 3.1. Base material Resin materials, for example, can be used as a constituent material of the substrate 4. Examples of resin materials used for the substrate 4 include thermoplastic resins such as olefin resins, polyester resins (ester polymers) such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, polyvinyl chloride resins, polyurethanes, polyimides, polyamides, polyether ketones such as polyether ether ketone, polyethersulfone, polystyrene, fluororesins, silicone resins, cellulose resins, styrene thermoplastic elastomers (styrene polymers), acrylic resins, polyester thermoplastic elastomers, polyvinyl isoprene, and polycarbonates (carbonate polymers), as well as mixtures containing these thermoplastic resins.

[0048] These resin materials are materials that can transmit energy rays such as visible light, near-infrared rays, ultraviolet rays, X-rays, and electron beams, and therefore, in the energy ray irradiation treatment described above, the irradiated energy rays E penetrate the base material 4 and are irradiated onto the adhesive layer 2. Therefore, the adhesive strength of the adhesive layer 2 can be more reliably reduced.

[0049] The substrate 4 may contain softeners such as mineral oil, fillers such as calcium carbonate, silica, talc, mica, and clay, antioxidants, light stabilizers, lubricants, dispersants, neutralizers, colorants, and the like.

[0050] The content of the resin material in the base material 4 is preferably 50% by mass or more, and more preferably 80% by mass or more, which ensures good flexibility of the base material 4 and good adhesion of the base material 4 to the adhesive layer 2.

[0051] The thickness of the substrate 4 is not particularly limited, but is preferably 30 μm or more and 200 μm or less, and more preferably 40 μm or more and 150 μm or less. When the thickness of the substrate 4 is within this range, the mechanical properties of the substrate 4 are optimized, and the substrate 4 can more reliably perform its functions. This makes it possible to prevent breakage of the substrate 4 during dicing, expanding, picking up, and other processes.

[0052] The surface roughness Ra of the substrate 4 is, for example, preferably 0.2 μm or more and 2.0 μm or less, and more preferably 0.5 μm or more and 1.5 μm or less. When the surface roughness Ra of the substrate 4 is within this range, the adhesion between the substrate 4 and the adhesive layer 2 is improved. This makes it possible to prevent peeling between the substrate 4 and the adhesive layer 2 during the pick-up process.

[0053] 3.2. Adhesive layer The adhesive layer 2 has enough adhesiveness to support the semiconductor substrate 7 during the dicing process and to allow the semiconductor chip 20 to be picked up well during the pick-up process. The adhesive layer 2 of the adhesive tape 100 according to this embodiment contains a double bond-introduced acrylic resin (A) as a base resin, and a photopolymerization initiator (B).

[0054] 3.2.1. Double bond-introduced acrylic resin (A) The double bond-introduced acrylic resin (A) is an adhesive and provides the adhesive layer 2 with adhesiveness to the semiconductor substrate 7. The double bond-introduced acrylic resin (A) is an acrylic resin having an unsaturated double bond in its side chain. The unsaturated double bond is not particularly limited as long as it is an unsaturated double bond, but is preferably a polymerizable carbon-carbon double bond (ethylenically unsaturated double bond) that can be three-dimensionally crosslinked by irradiation with energy rays. Having a group containing such a polymerizable carbon-carbon double bond in its side chain more reliably forms three-dimensional crosslinks within the polymer main chain of the double bond-introduced acrylic resin (A) or between polymer main chains. The double bond-introduced acrylic resin (A) also has the effect of suppressing detachment of the photopolymerization initiator (B) from the adhesive layer 2. Specific examples of the group containing a polymerizable carbon-carbon double bond include a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, an allyl group, a 1-propenyl group, and a vinyl group.

[0055] In this specification, the acrylic resin refers to a polymer (homopolymer or copolymer) containing a (meth)acrylic acid ester as a monomer component. In addition, in this specification, (meth)acrylic acid includes both acrylic acid and methacrylic acid. Therefore, for example, (meth)acrylic acid ester includes both acrylic acid ester and methacrylic acid ester.

[0056] The double bond-introduced acrylic resin (A) is a polymer containing a structure derived from a (meth)acrylic acid ester as a main structural unit, and is an acrylic resin having a polymer main chain and a side chain bonded to the polymer main chain and containing an unsaturated double bond.

[0057] The double bond-introduced acrylic resin (A) is synthesized, for example, by a method including the steps of: obtaining an acrylic resin having a reactive functional group by copolymerizing one or more (meth)acrylic acid esters (A-1) with one or more polymerizable compounds (A-2) having a reactive functional group in the side chain; and reacting the acrylic resin with one or more compounds (A-3) having a functional group reactive with the reactive functional group and an unsaturated double bond.

[0058] Such double bond-introduced acrylic resin (A) has unsaturated double bonds in its side chains, and thus forms three-dimensional crosslinks within and between polymer main chains. Furthermore, the double bond-introduced acrylic resin (A) suppresses the detachment of the photopolymerization initiator (B) from the adhesive layer 2 during a heat resistance test. This effect is exhibited when the molecular weight of the photopolymerization initiator (B) is within a predetermined range. When the detachment of the photopolymerization initiator (B) is suppressed, the adhesive strength of the adhesive tape 100 can be sufficiently reduced by energy ray irradiation treatment, even after the heat resistance test.

[0059] Examples of the (meth)acrylic acid ester (A-1) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, and decyl (meth)acrylate. (meth)acrylic acid alkyl esters such as isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and octadecyl (meth)acrylate; (meth)acrylic acid cycloalkyl esters such as cyclohexyl (meth)acrylate; and (meth)acrylic acid aryl esters such as phenyl (meth)acrylate, and these may be used alone or in combination of two or more.

[0060] Among these, (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate are preferably used as the (meth)acrylic acid ester (A-1). (Meth)acrylic acid alkyl esters have excellent heat resistance and are relatively easy and inexpensive to obtain.

[0061] The proportion of the (meth)acrylic acid ester (A-1) in the double bond-introduced acrylic resin (A) is preferably 50% by mass or more and 99% by mass or less, and more preferably 70% by mass or more and 95% by mass or less, based on the total mass of the monomer components constituting the double bond-introduced acrylic resin (A).

[0062] The polymerizable compound (A-2) is a polymerizable compound having a reactive functional group. Examples of the reactive functional group include a carboxyl group, a hydroxyl group, an amino group, a mercapto group, a cyclic acid anhydride group, and an epoxy group. Among these, when the reactive functional group is a carboxyl group, a hydroxyl group, an amino group, a mercapto group, or a cyclic acid anhydride group, the reactivity with a compound (A-3) having, for example, an epoxy group or an isocyanate group as a functional group is good. Furthermore, when the reactive functional group is a cyclic acid anhydride group, the reactivity with a compound (A-3) having, for example, a carboxyl group, a hydroxyl group, an amino group, a mercapto group, or a functional group is good.

[0063] Examples of the polymerizable compound (A-2) having an epoxy group as a reactive functional group include glycidyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate.

[0064] Examples of the polymerizable compound (A-2) having a hydroxyl group as a reactive functional group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and glycerin mono(meth)acrylate.

[0065] Examples of the polymerizable compound (A-2) having a carboxyl group as a reactive functional group include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0066] The acrylic resin may contain, in addition to the (meth)acrylic acid ester (A-1) and the polymerizable compound (A-2), other polymerizable compounds as monomer units, such as aromatic vinyl compounds such as styrene and vinyltoluene.

[0067] The compound (A-3) is a compound having a functional group that reacts with the reactive functional group of the polymerizable compound (A-2) and an unsaturated double bond.

[0068] Examples of the compound (A-3) having a carboxyl group include (meth)acrylic acid, a dimer of (meth)acrylic acid, caprolactone-modified (meth)acrylic acid, a compound obtained by a ring-opening reaction between a (meth)acrylate having a hydroxyl group and a carboxylic acid anhydride, and β-acryloyloxyethyl hydrogen succinate.

[0069] Examples of the compound (A-3) having an isocyanate group include methacryloyloxyethyl isocyanate.

[0070] Examples of the compound (A-3) having an epoxy group include glycidyl (meth)acrylate and allyl glycidyl ether.

[0071] The double bond-introduced acrylic resin (A) can be produced by polymerizing a single monomer component or a mixture of two or more monomer components. The polymerization of these monomer components can be carried out using a polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization.

[0072] From the viewpoint of preventing contamination of the semiconductor substrate 7 and the like during dicing, the double bond-introduced acrylic resin (A) preferably contains a small amount of low-molecular-weight substances. From this viewpoint, the weight-average molecular weight of the double bond-introduced acrylic resin (A) is preferably 300,000 to 5,000,000, more preferably 400,000 to 4,000,000, and even more preferably 500,000 to 1,500,000. If the weight-average molecular weight of the double bond-introduced acrylic resin (A) is below the lower limit, depending on the type of monomer component, the contamination prevention properties against the semiconductor substrate 7 and the like may be reduced, resulting in the risk of components contained in the adhesive layer 2 adhering to the semiconductor chip 20. On the other hand, if the weight-average molecular weight of the double bond-introduced acrylic resin (A) is above the upper limit, the viscosity of the composition for forming the adhesive layer 2 may be increased, which may increase the difficulty of manufacturing the adhesive tape 100. The weight-average molecular weight is calculated using standard polystyrene equivalents by gel permeation chromatography (GPC).

[0073] The glass transition temperature Tg of the double bond-introduced acrylic resin (A) is preferably -70°C or higher and -10°C or lower, more preferably -50°C or higher and -20°C or lower, and even more preferably -45°C or higher and -25°C or lower. This allows the adhesive strength of the adhesive layer 2 to be optimized. If the glass transition temperature Tg is lower than the lower limit, the double bond-introduced acrylic resin (A) becomes less likely to aggregate, which may result in components contained in the adhesive layer adhering to the picked-up semiconductor chip 20. On the other hand, if the glass transition temperature Tg is higher than the upper limit, the adhesive strength of the adhesive layer 2 may be insufficient, which may result in defects during the dicing process.

[0074] The glass transition temperature Tg is appropriately adjusted depending on the monomer components constituting the double bond-introduced acrylic resin (A), the molecular weight, etc. The glass transition temperature Tg is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 0.1°C / min.

[0075] The unsaturated double bond equivalent of the double bond-introduced acrylic resin (A) is preferably 200 or more and 4000 or less, more preferably 250 or more and 3000 or less. The unsaturated double bond equivalent of the double bond-introduced acrylic resin (A) tends to reflect the adhesiveness, curability, and retention of the photopolymerization initiator (B). Therefore, if the unsaturated double bond equivalent is within the above range, an adhesive layer 2 can be obtained that can more reliably suppress detachment of the photopolymerization initiator (B). Furthermore, an adhesive layer 2 that is excellent in heat resistance and has good adhesiveness and curability even after a heat resistance test can be obtained. Note that if the unsaturated double bond equivalent is below the above lower limit, the effect of suppressing detachment of the photopolymerization initiator (B) during a heat resistance test may be reduced, or the peelability of the adhesive layer 2 may be reduced after energy ray irradiation treatment.

[0076] The equivalent weight of the unsaturated double bond of the double bond-introduced acrylic resin (A) is calculated by "molecular weight / number of unsaturated double bonds in the same molecule."

[0077] The content of the double bond-introduced acrylic resin (A) in the resin composition constituting the adhesive layer 2 is preferably 30% by mass or more and 90% by mass or less of the total solid content of the resin composition, and more preferably 40% by mass or more and 80% by mass or less.

[0078] 3.2.2. Photopolymerization initiator (B) The photopolymerization initiator (B) facilitates the initiation of polymerization of the double bond-introduced acrylic resin (A).

[0079] The photopolymerization initiator (B) is a compound having a molecular weight of 300 or more and 2,000 or less. If the molecular weight of the photopolymerization initiator (B) is within the above range, the photopolymerization initiator (B) is less likely to be detached from the adhesive layer 2 even after a heat resistance test. Therefore, by suppressing the detachment of the photopolymerization initiator (B), a sufficient amount of the photopolymerization initiator (B) is present in the adhesive layer 2 even after the heat resistance test. This can promote the curing of the double bond-introduced acrylic resin (A) when an energy ray irradiation treatment is performed. As a result, the adhesive strength of the adhesive tape 100 after the energy ray irradiation treatment can be sufficiently reduced.

[0080] As mentioned above, the molecular weight of the photopolymerization initiator (B) is 300 or more and 2,000 or less, preferably 300 or more and 1,500 or less, and more preferably 300 or more and 1,000 or less. If the molecular weight of the photopolymerization initiator (B) is below the lower limit, the photopolymerization initiator (B) is likely to detach from the adhesive layer 2 in a heat resistance test. This makes it difficult for the adhesive layer 2 to cure even when subjected to an energy ray irradiation treatment. On the other hand, if the molecular weight of the photopolymerization initiator (B) is above the upper limit, the compatibility of the photopolymerization initiator (B) with other components decreases.

[0081] Examples of such photopolymerization initiators (B) include benzophenone-based compounds, acetophenone-based compounds, benzoin-based compounds, α-hydroxyketone-based compounds, α-aminoketone-based compounds, α-diketone-based compounds, α-diketone dialkyl acetal-based compounds, anthraquinone-based compounds, thioxanthone-based compounds, phosphine oxide-based compounds, and oxime ester-based compounds, and one or more of these may be used.

[0082] Among these, examples of the α-hydroxyketone compounds include oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone (ESACURE (registered trademark) ONE, manufactured by IGM Resins), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)phenoxy]phenyl}-2-methylpropan-1-one (ESACURE KIP160, manufactured by IGM Resins), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one (Omnirad (registered trademark) 127, manufactured by IGM Resins BV).

[0083] Examples of α-aminoketone compounds include 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone (manufactured by IGM Resins BV, Omnirad 379EG) and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 (manufactured by IGM Resins BV, Omnirad 369).

[0084] Examples of phosphine oxide compounds include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (manufactured by IGM Resins BV, Omnirad TPO H) and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins BV, Omnirad 819).

[0085] Examples of oxime ester compounds include 1-[4-(phenylthio)]-1,2-octanedione-2-(O-benzoyloxime) (manufactured by BASF Japan, IRGACURE (registered trademark) OXE-01) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetyloxime) (manufactured by BASF Japan, IRGACURE OXE-02).

[0086] Other examples include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbisimidazole (2-(2-chlorophenyl)-4,5-diphenylimidazole dimer) (manufactured by Hampford, B-CIM) and 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer (manufactured by Tokyo Chemical Industry Co., Ltd., BCTB).

[0087] Among these, an α-hydroxyketone compound is preferably used as the photopolymerization initiator (B). The α-hydroxyketone compound is useful as the photopolymerization initiator (B) because it has excellent curing properties for the double bond-introduced acrylic resin (A) and excellent compatibility with other components even when it has a high molecular weight.

[0088] Furthermore, the weight loss rate of the photopolymerization initiator (B) after heating in air at a temperature of 150°C for 1 hour is preferably 20.0% or less, more preferably 18.0% or less, and even more preferably 16.0% or less. When the weight loss rate of the photopolymerization initiator (B) is within the above range, the amount of evaporation of the photopolymerization initiator (B) during a heat resistance test can be sufficiently suppressed. As a result, even after the heat resistance test, a sufficient amount of the photopolymerization initiator (B) is present, and an adhesive layer 2 having excellent curability by energy ray irradiation treatment can be obtained.

[0089] The weight loss rate of the photopolymerization initiator (B) is measured as follows. First, weigh out approximately 1 g of photopolymerization initiator (B) and place it in an aluminum cup. Next, measure the weight of the photopolymerization initiator (B) using a precision balance and record it as the "weight before heat resistance test." Next, place the aluminum cup in an oven and heat it in the air at a temperature of 150°C for 1 hour. After heating is complete, remove the aluminum cup from the oven. Next, quickly measure the weight of the photopolymerization initiator (B) removed from the oven using a precision balance and record it as the "weight after heat resistance test." Then, calculate the weight loss rate (%) using the following formula. (Weight loss rate) = {(Weight before heat resistance test) - (Weight after heat resistance test)} / (Weight before heat resistance test) × 100

[0090] Furthermore, a photopolymerization initiator other than the photopolymerization initiator (B) (hereinafter referred to as "another photopolymerization initiator") may be used in combination with the adhesive layer 2. The other photopolymerization initiator may be selected from, for example, the compounds described above, and may have a molecular weight of less than 300. By using such an other photopolymerization initiator in combination, for example, an effect of improving the curability can be obtained even when the adhesive layer 2 is made thick.

[0091] In this case, the content of the photopolymerization initiator (B) in the adhesive layer 2 is preferably higher than the content of the other photopolymerization initiators. This ensures the effects of the photopolymerization initiator (B). The ratio of the photopolymerization initiator (B) to the total amount of the photopolymerization initiator (B) and the other photopolymerization initiators is preferably 60% by mass or more, and more preferably 80% by mass or more.

[0092] The photopolymerization initiator (B) is preferably blended in an amount of 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the double bond-introduced acrylic resin (A). By adjusting the blending amount of the photopolymerization initiator (B) as described above, the function of the photopolymerization initiator (B) can be more reliably exhibited and excess photopolymerization initiator (B) can be avoided.

[0093] If the blending ratio of the photopolymerization initiator (B) is below the lower limit, the blending amount of the photopolymerization initiator (B) will be insufficient, and curability may decrease when an energy ray irradiation treatment is performed. On the other hand, if the blending ratio of the photopolymerization initiator (B) is above the upper limit, the cohesive force of the adhesive layer 2 will decrease due to the excess photopolymerization initiator (B), and there is a risk that the adhesive will be transferred to the surface of the adherend after peeling from the adherend.

[0094] 3.2.3. Curing resin (C) The adhesive layer 2 may contain a curable resin (C). The curable resin (C) is a resin that has the curability to be cured by irradiation with energy rays. The curable resin (C) may be a resin having a polymerizable functional group that polymerizes by irradiation with energy rays, but is preferably a resin having a group containing a polymerizable carbon-carbon double bond that can be three-dimensionally crosslinked by irradiation with energy rays. By containing such a curable resin (C), the adhesive strength of the adhesive layer 2 after the UV reaction (after irradiation with energy rays) can be further reduced.

[0095] Specific examples of the group containing a polymerizable carbon-carbon double bond include a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, an allyl group, a 1-propenyl group, and a vinyl group.

[0096] Examples of the curable resin (C) include low molecular weight compounds having in the molecule at least two groups containing polymerizable carbon-carbon double bonds that can be three-dimensionally crosslinked by irradiation with energy rays. Specific examples of the compound include esters of (meth)acrylic acid and polyhydric alcohols such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and glycerin di(meth)acrylate; ester acrylate oligomers; cyanurate compounds having a carbon-carbon double bond-containing group such as 2-propenyl-di-3-butenyl cyanurate; tris(2-acryloxyethyl)isocyanurate; tris(2-methyl)isocyanurate; Examples of the acrylic acid acrylate include isocyanurate compounds having a carbon-carbon double bond-containing group, such as tris(1,3-diacryloxy-2-propyl-oxycarbonylamino-n-hexyl)isocyanurate, 2-hydroxyethylbis(2-acryloxyethyl)isocyanurate, bis(2-acryloxyethyl)2-[(5-acryloxyhexyl)-oxy]ethyl isocyanurate, tris(1,3-diacryloxy-2-propyl-oxycarbonylamino-n-hexyl)isocyanurate, tris(1-acryloxyethyl-3-methacryloxy-2-propyl-oxycarbonylamino-n-hexyl)isocyanurate, and tris(4-acryloxy-n-butyl)isocyanurate; commercially available oligoester acrylates; aromatic and aliphatic urethane acrylates; and epoxy acrylates such as bisphenol A epoxy acrylate, phenol novolac epoxy acrylate, and cresol novolac epoxy acrylate. These may be used alone or in combination of two or more.

[0097] Among these, it is preferable to include at least one of an ester of (meth)acrylic acid and a polyhydric alcohol, a urethane acrylate, and an epoxy acrylate, and it is more preferable to include a bisphenol A-type epoxy acrylate, which allows the curable resin (C) to be cured more reliably by irradiation with energy rays.

[0098] The number of functional groups (the number of groups containing a polymerizable carbon-carbon double bond) per molecule of the curable resin (C) may be 2 or more, preferably 3 or more, and more preferably 4 or more. This can increase the reactivity of the curable resin (C), and in the adhesive layer 2, it is possible to more reliably achieve good releasability by energy ray irradiation treatment and suppression of defects in the pick-up treatment.

[0099] The weight-average molecular weight of the curable resin (C) is preferably smaller than that of the double bond-introduced acrylic resin (A). It is more preferably 100 to 15,000, and even more preferably 200 to 5,000. This ensures that the adhesive layer 2 has sufficient adhesive strength after UV reaction (after irradiation with energy rays). The weight-average molecular weight is measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0100] The blending ratio of the curable resin (C) is preferably more than 0 parts by mass and not more than 100 parts by mass, more preferably 15 parts by mass or more and not more than 90 parts by mass, even more preferably 20 parts by mass or more and not more than 70 parts by mass, and particularly preferably 50 parts by mass or more and not more than 70 parts by mass, relative to 100 parts by mass of the double bond-introduced acrylic resin (A). This allows the above-mentioned effect of using the double bond-introduced acrylic resin (A) and the curable resin (C) in combination to be obtained. That is, the adhesive strength of the adhesive layer 2 can be sufficiently reduced after curing.

[0101] If the blending ratio of the curable resin (C) is below the lower limit, the adhesive layer 2 may be difficult to cure, which may reduce the peelability by the energy ray irradiation treatment or cause defects in the pick-up treatment. On the other hand, if the blending ratio of the curable resin (C) is above the upper limit, the curable resin (C) may become excessive.

[0102] 3.2.4. Crosslinker (D) The resin composition constituting the adhesive layer 2 may contain a crosslinking agent (D). By containing the crosslinking agent (D), the adhesive layer 2 can be adjusted to have an appropriate hardness.

[0103] The crosslinking agent (D) is not particularly limited, but examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, urea resin-based crosslinking agents, methylol-based crosslinking agents, chelate-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, polyvalent metal chelate-based crosslinking agents, acid anhydride-based crosslinking agents, polyamine-based crosslinking agents, carboxyl group-containing polymer-based crosslinking agents, etc. Among these, isocyanate-based crosslinking agents are preferred.

[0104] The isocyanate-based crosslinking agent is not particularly limited, but examples thereof include polyisocyanate compounds of polyvalent isocyanates, trimers of polyisocyanate compounds, trimers of isocyanate-terminated compounds obtained by reacting a polyisocyanate compound with a polyol compound, and blocked polyisocyanate compounds in which isocyanate-terminated urethane prepolymers are blocked with phenol, oximes, or the like.

[0105] Examples of polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, 4,4'-diphenylether diisocyanate, 4,4'-[2,2-bis(4-phenoxyphenyl)propane]diisocyanate, and 2,2,4-trimethyl-hexamethylene diisocyanate. These may be used alone or in combination of two or more. Among these, at least one polyisocyanate selected from the group consisting of 2,4-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and hexamethylene diisocyanate is preferred.

[0106] The crosslinking agent (D) is preferably blended in an amount of 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the double bond-introduced acrylic resin (A). By adjusting the blending amount of the crosslinking agent (D) as described above, the function exhibited by adding the crosslinking agent (D) to the resin composition can be reliably exhibited.

[0107] Plasticizers The adhesive layer 2 may contain a plasticizer. The plasticizer improves the flexibility of the adhesive layer 2. This allows the adhesive layer 2 to have excellent adhesion to, for example, the semiconductor substrate 7.

[0108] The plasticizer is not particularly limited, but examples thereof include phthalate ester plasticizers such as DOP (dioctyl phthalate), DBP (dibutyl phthalate), DIBP (diisobutyl phthalate), and DHP (diheptyl phthalate), aliphatic dibasic acid ester plasticizers such as DOA (di-2-ethylhexyl adipate), DIDA (diisodecyl adipate), and DOS (di-2-ethylhexyl sebacate), aromatic carboxylic acid ester plasticizers such as ethylene glycol benzoates, trimellitic acid ester plasticizers such as TOTM (trioctyl trimellitate), and adipate ester plasticizers, and these may be used alone or in combination of two or more.

[0109] The plasticizer is preferably blended in an amount of 0.1 to 5.0 parts by mass, more preferably 0.5 to 3.0 parts by mass, per 100 parts by mass of the double bond-introduced acrylic resin (A), thereby obtaining an adhesive layer 2 that maintains flexibility and has excellent adhesion to the semiconductor substrate 7.

[0110] 3.2.6. Other ingredients The resin composition forming the adhesive layer 2 may contain one or more of the following other components: conductive materials, tackifiers, antioxidants, adhesion adjusters, fillers, colorants, flame retardants, softeners, antioxidants, surfactants, etc.

[0111] Among these, examples of tackifiers include rosin resins, terpene resins, coumarone resins, phenolic resins, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic-aromatic copolymer petroleum resins, and these may be used alone or in combination of two or more.

[0112] 3.2.7. Thickness of adhesive layer, etc. The thickness of the adhesive layer 2 is not particularly limited, but is preferably 5 μm to 100 μm, more preferably 5 μm to 50 μm. By setting the thickness of the adhesive layer 2 within this range, it is possible to achieve an adhesive layer 2 that exhibits good adhesion to the semiconductor substrate 7 during the dicing process and good releasability during the pick-up process.

[0113] The adhesive layer 2 may be composed of a laminate (multilayer body) in which a plurality of layers composed of different resin compositions are laminated.

[0114] 4. Manufacturing method of adhesive tape Next, an example of a method for manufacturing the adhesive tape 100 will be described.

[0115] [1B] First, prepare the substrate 4. The method for producing the substrate 4 is not particularly limited, but examples thereof include common molding methods such as extrusion molding methods such as a calendar method, an inflation extrusion method, and a T-die extrusion method, and a wet casting method.

[0116] The upper surface of the substrate 4 may be previously subjected to a surface treatment such as corona treatment, chromic acid treatment, matte treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, ionizing radiation treatment, primer treatment, or anchor coat treatment, thereby improving the adhesion between the substrate 4 and the adhesive layer 2.

[0117] [2B] Next, adhesive layer 2 is formed on the upper surface of substrate 4. Adhesive layer 2 is formed by coating or spraying a liquid material made by dissolving a resin composition in a solvent to form a varnish on the upper surface of a film such as polyethylene terephthalate, then volatilizing the solvent to form a layer, and then transferring the layer to substrate 4.

[0118] The solvent is not particularly limited, but examples thereof include methyl ethyl ketone, acetone, toluene, ethyl acetate, dimethyl formaldehyde, etc., and one or more of these can be used in combination.

[0119] Furthermore, the liquid material can be applied or sprayed onto the substrate 4 using methods such as die coating, curtain die coating, gravure coating, comma coating, bar coating, and lip coating.

[0120] Thereafter, if necessary, a process for removing a part of the adhesive layer 2, a process for laminating a separator, etc. may be carried out. In this manner, the adhesive tape 100 is obtained.

[0121] 5. Effects of the above embodiment The pressure-sensitive adhesive tape 100 according to the embodiment is an adhesive tape used for temporarily fixing a semiconductor substrate 7 (substrate), and includes a base material 4 and an adhesive layer 2 laminated on the upper surface (one surface) of the base material 4. The adhesive layer 2 contains a double-bond-introduced acrylic resin (A) having an unsaturated double bond in its side chain, and a photopolymerization initiator (B) having a molecular weight of 300 or more and 2,000 or less.

[0122] With this configuration, even after a heat resistance test, the adhesive strength of the adhesive tape 100 can be sufficiently reduced by the energy ray irradiation treatment. This allows the pickup treatment to be carried out smoothly. Furthermore, the occurrence of problems such as components contained in the adhesive layer 2 adhering to the semiconductor chip 20 can be suppressed.

[0123] Furthermore, since heating can be performed before the energy beam irradiation process, a reliability test involving heating can be performed while the semiconductor chips 20 are fixed to the adhesive tape 100. This eliminates the need to transport the semiconductor chips 20 individually, as was conventionally the case, and reduces the number of steps required for the reliability test, thereby improving the manufacturing efficiency of the semiconductor device 10.

[0124] The photopolymerization initiator (B) preferably contains an α-hydroxyketone-based photopolymerization initiator.

[0125] The α-hydroxyketone compound is useful as the photopolymerization initiator (B) because it has excellent curing properties for the double bond-introduced acrylic resin (A) and also has excellent compatibility with other components even when it has a high molecular weight.

[0126] Furthermore, the photopolymerization initiator (B) preferably exhibits a weight loss rate of 20.0% or less after being heated in the air at a temperature of 150° C. for 1 hour.

[0127] According to this configuration, the amount of evaporation of the photopolymerization initiator (B) during the heat resistance test can be sufficiently suppressed, and as a result, even after the heat resistance test, the photopolymerization initiator (B) remains in sufficient quantity, and the adhesive layer 2 exhibits excellent curability upon energy ray irradiation treatment.

[0128] The blending ratio of the photopolymerization initiator (B) to 100 parts by mass of the double bond-introduced acrylic resin (A) is preferably 0.1 parts by mass or more and 20 parts by mass or less.

[0129] According to this configuration, the photopolymerization initiator (B) can more reliably exhibit its function, and excess photopolymerization initiator (B) can be avoided.

[0130] Although the pressure-sensitive adhesive tape of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0131] For example, each layer of the pressure-sensitive adhesive tape of the present invention may contain a component other than the components described in the above embodiment. Furthermore, the pressure-sensitive adhesive tape of the present invention may have an optional layer added to the layer configuration described in the above embodiment. In this case, the location of the additional layer is not particularly limited, and may be on the upper surface of the pressure-sensitive adhesive layer, on the lower surface of the substrate, or between the pressure-sensitive adhesive layer and the substrate. Furthermore, the substrate may be composed of multiple layers.

[0132] Furthermore, the substrate to be temporarily fixed by the pressure-sensitive adhesive tape of the present invention is not limited to the above-mentioned semiconductor substrate (semiconductor wafer), and may be, for example, a glass substrate such as soda-lime glass, borosilicate glass, or quartz glass, a ceramic substrate such as alumina, silicon nitride, or titanium oxide, a resin substrate such as acrylic, polycarbonate, or rubber, a single crystal substrate such as quartz or sapphire, or a metal plate, etc. Furthermore, members such as chips obtained by dividing a wafer are also included in the substrate to be temporarily fixed by the pressure-sensitive adhesive tape. [Example]

[0133] Next, specific examples of the present invention will be described, but the present invention is not limited to the descriptions of these examples.

[0134] 6. Preparation of Adhesive Tape An adhesive tape was prepared using the following materials.

[0135] 6.1. Preparation of raw materials Table 1 shows the base resin, photopolymerization initiator, curable resin, and crosslinking agent used in preparing the adhesive layer.

[0136] The base resins a1-1, a1-2, a1-3, a1-4, and a2 shown in Table 1 are each an acrylic copolymer obtained by mixing at least two of butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, acrylic acid, 2-hydroxyethyl acrylate, N,N-dimethylacrylamide, and vinyl acetate, and solution-polymerizing the mixture in toluene using a conventional method.

[0137] As an example, the manufacturing method of base resin a1-1 will be described. First, an acrylic resin was prepared by copolymerizing butyl acrylate and acrylic acid. Next, this acrylic resin was reacted with glycidyl methacrylate (GMA). As a result, a double bond-introduced acrylic resin (base resin a1-1) was obtained, in which a structure derived from GMA was introduced as a side chain into the polymer main chain via an ester bond.

[0138] In addition, if each base resin is a double bond-introduced acrylic resin having an unsaturated double bond in the side chain, it is marked with a circle in Table 1, and if an unsaturated double bond is not introduced in the side chain, it is marked with an × in Table 1.

[0139] Table 1 also shows the main monomer component, the glass transition temperature Tg (theoretical Tg before the introduction of side-chain double bonds) of the backbone polymer, and the weight-average molecular weight Mw of each base resin. The main monomer component refers to the component with the highest mass content among all monomer components. Each base resin was synthesized by changing the blend and molecular weight of the monomer components so that these physical properties would achieve the values ​​shown in Table 1. The double bond equivalent weight of the double bond-introduced acrylic resins was in the range of 200 to 4000. Among the symbols representing the main monomer components, BA stands for butyl acrylate, and 2-EHA stands for 2-ethylhexyl acrylate.

[0140] Table 1 also shows the weight loss rates and molecular weights of the photopolymerization initiators b1-1, b1-2, b1-3, b1-4, b1-5, b2-1, and b2-2.

[0141] [Table 1]

[0142] 6.2. Preparation of adhesive layer First, a liquid material was prepared by blending the raw materials for the adhesive layer shown in Tables 2 and 3 in a predetermined ratio. Next, this liquid material was bar-coated onto a polyethylene terephthalate film so that the thickness after drying would be the value shown in Tables 2 and 3. The resulting coating was dried at 80°C for 1 minute and transferred onto the substrate shown in Tables 2 and 3 to obtain an adhesive layer.

[0143] The constituent materials and thicknesses of the substrates used to prepare the adhesive tapes are shown in Tables 2 and 3. Of the constituent materials, PET stands for polyethylene terephthalate, and PBT elastomer stands for polyester thermoplastic elastomer containing polybutylene terephthalate segments.

[0144] In Tables 2 and 3, examples corresponding to the present invention are designated as "Examples," and examples not corresponding to the present invention are designated as "Comparative Examples."

[0145] 7. Evaluation of adhesive tapes Next, the produced pressure-sensitive adhesive tapes were evaluated for the following items.

[0146] 7.1. Behavior of adhesive strength before and after UV irradiation The adhesive strength of the adhesive tape was measured while varying the presence or absence of heating and ultraviolet irradiation of the test piece as follows.

[0147] 7.1.1. Obtaining measurements at 23°C before UV exposure Strip-shaped test pieces measuring 25 mm in width and 300 mm in length were cut from the pressure-sensitive adhesive tapes of each Example and Comparative Example. Next, a 180-degree peel test was performed on the obtained test pieces in a test environment of 23±1°C and 50±5% relative humidity, and the peel strength of the test piece relative to the test plate was measured. A silicon wafer was used as the test plate. The 180-degree peel test involved attaching a test piece to the mirror surface of a silicon wafer, and then peeling it off in a 180-degree direction after 30 minutes, while measuring the peel strength at a peel rate of 300 mm / min. The mirror surface of the silicon wafer was a mirror-finished surface as specified in JIS H 0614:1996. The obtained peel strength was recorded as a measurement value at 23°C before UV irradiation. These measurements were then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.

[0148] A: The measured value at 23°C before UV exposure is 50cN / 25mm or more. B: The measured value at 23°C before UV exposure is 30cN / 25mm or more and less than 50cN / 25mm C: The measured value at 23°C before UV exposure is less than 30cN / 25mm

[0149] 7.1.2. Obtaining measurements after heating at 150°C for 60 minutes and before UV irradiation A strip-shaped test piece measuring 25 mm in width and 300 mm in length was cut from the pressure-sensitive adhesive tape of each Example and Comparative Example. The resulting test piece was then heated in the atmosphere at 150°C for 60 minutes. The heated test piece was then subjected to a 180° peel test in the above-mentioned test environment, and the peel strength of the test piece relative to the test plate was measured. The obtained peel strength was recorded as the measurement value "after heating at 150°C for 60 minutes and before UV irradiation." This measurement value was then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.

[0150] A: The measured value "after heating at 150°C for 60 minutes and before UV irradiation" is 50cN / 25mm or more. B: The measured value "after heating at 150°C for 60 minutes and before UV irradiation" is 30cN / 25mm or more and less than 50cN / 25mm C: The measured value "after heating at 150°C for 60 minutes and before UV irradiation" is less than 30cN / 25mm

[0151] 7.1.3. Obtaining measurements after heating at 150°C for 60 minutes and irradiating with ultraviolet light A strip-shaped test piece having a width of 25 mm and a length of 300 mm was cut out from the adhesive tape of each Example and Comparative Example. Next, the obtained test piece was heated in the atmosphere at a temperature of 150°C for 60 minutes. Subsequently, the heated test piece was exposed to ultraviolet ray irradiance of 55 W / cm. 2 , UV irradiation amount: 200mJ / cm 2 The adhesive layer was cured by irradiating it with ultraviolet light under the above conditions. Next, a 180-degree peel test was performed on the test piece after ultraviolet irradiation under the above test environment, and the peel strength of the test piece against the test plate was measured. The obtained peel strength was recorded as the measured value "after heating at 150°C for 60 minutes and after ultraviolet irradiation." This measured value was then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.

[0152] A: The measured value after heating at 150°C for 60 minutes and irradiating with ultraviolet light is 30cN / 25mm or less. B: The measured value "after heating at 150°C for 60 minutes and irradiating with ultraviolet light" is more than 30cN / 25mm and 50cN / 25mm or less C: The measured value "after heating at 150°C for 60 minutes and irradiating with ultraviolet light" is more than 50cN / 25mm

[0153] 7.1.4. Obtaining measurements after heating at 150°C for 240 minutes and irradiating with ultraviolet light A strip-shaped test piece having a width of 25 mm and a length of 300 mm was cut out from the adhesive tape of each Example and Comparative Example. The test piece was then heated in the atmosphere at a temperature of 150°C for 240 minutes. Subsequently, the heated test piece was exposed to ultraviolet light at an irradiance of 55 W / cm. 2 , UV irradiation amount: 200mJ / cm 2 The adhesive layer was cured by irradiating it with ultraviolet light under the above conditions. Next, a 180-degree peel test was performed on the test piece after ultraviolet irradiation under the above test environment, and the peel strength of the test piece against the test plate was measured. The obtained peel strength was recorded as the measured value "after heating at 150°C for 240 minutes and after ultraviolet irradiation." This measured value was then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.

[0154] A: The measured value after heating at 150°C for 240 minutes and irradiating with ultraviolet light is 30cN / 25mm or less. B: The measured value "after heating at 150°C for 240 minutes and irradiating with ultraviolet light" is more than 30cN / 25mm and 50cN / 25mm or less C: The measured value "after heating at 150°C for 240 minutes and irradiating with ultraviolet light" is more than 50cN / 25mm

[0155] 7.2. Whether or not adhesive layer components adhere after heating and UV irradiation After obtaining measurements "after heating at 150°C for 60 minutes and irradiating with ultraviolet light," the test plate (silicon wafer) was observed for the presence or absence of residue (components contained in the adhesive layer). The observation results were then evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.

[0156] A: Little residue adhered (less than 5% of the outer circumference of the test piece) B: There is a little bit of residue (5% or more but less than 20% of the outer periphery of the test piece) C: A large amount of residue adheres (more than 20% of the outer circumference of the test piece)

[0157] [Table 2]

[0158] [Table 3]

[0159] From the results shown in Tables 2 and 3, the following was observed. By using a double bond-introduced acrylic resin and a photopolymerization initiator with a molecular weight within a specified range as raw materials for the adhesive layer, the adhesive layer had sufficiently high adhesive strength before the heat resistance test, and after the heat resistance test, the adhesive layer was hardened by irradiating it with energy rays, which allowed the adhesive strength to be sufficiently reduced. When either a double bond-introduced acrylic resin or a photopolymerization initiator with a molecular weight within the specified range was not used, good results were not obtained. This tendency was particularly pronounced when a thermoplastic elastomer was used as the base material. Better evaluation results were obtained by optimizing the glass transition temperature (Tg) and weight average molecular weight (Mw) of the base resin.

[0160] Examples were also produced in which the average thickness of the adhesive layer 2 was changed to 3 μm and 10 μm, but the evaluation results showed the same tendency as the evaluation results shown in Tables 2 and 3 for the case of 5 μm. [Explanation of symbols]

[0161] 2 Adhesive layer 4 Base material 7. Semiconductor substrate 9 wafer rings 10 Semiconductor devices 17 Mold section 20 Semiconductor chips 21 terminals 23 Semiconductor chip body 30 Interposer 41 terminals 70 Bump 71 Surface 72 Back side 80 Sealing layer 81 Connection 100 adhesive tape 121 Outer periphery 122 Central part 200 Dicer Table 300 Expandable Table 310 Extended Stage 320 Holding stand 400 Pickup Table 500 protective tape 600 chuck table E energy ray H fever

Claims

1. An adhesive tape used to temporarily fix a substrate, comprising a base material and an adhesive layer laminated on one surface of the base material, The adhesive layer is a double bond-introduced acrylic resin (A) having an unsaturated double bond in a side chain; a photopolymerization initiator (B) having a molecular weight of 300 or more and 2,000 or less; An adhesive tape comprising:

2. The pressure-sensitive adhesive tape according to claim 1, wherein the photopolymerization initiator (B) comprises an α-hydroxyketone-based photopolymerization initiator.

3. 3. The pressure-sensitive adhesive tape according to claim 1, wherein the photopolymerization initiator (B) exhibits a weight loss rate of 20.0% or less after being heated in the atmosphere at a temperature of 150°C for 1 hour.

4. 3. The pressure-sensitive adhesive tape according to claim 1, wherein a mixing ratio of the photopolymerization initiator (B) to 100 parts by mass of the double bond-introduced acrylic resin (A) is 0.1 parts by mass or more and 20 parts by mass or less.

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