Adhesive tape for semiconductor processing and method for manufacturing semiconductor device

Abstract

[Problem] To provide a semiconductor processing adhesive tape capable of suppressing the cracking of chips when peeling off the adhesive tape.　[Solution] A semiconductor processing adhesive tape having a base material and an adhesive layer, wherein, in a state in which one face of the adhesive layer is exposed to the atmosphere, after the adhesive tape is irradiated with ultraviolet light under the conditions of an illuminance of 220mW / cm2 and a light quantity of 500 mJ / cm3, the surface modulus of elasticity of the exposed face of the adhesive layer is 5 MPa or more.　

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape for semiconductor processing, and more particularly to an adhesive tape preferably used to temporarily hold semiconductor wafers or chips when manufacturing semiconductor devices using a method that involves creating grooves on the surface of a wafer or creating a modified region inside a wafer with a laser, and then fragmenting the wafer by stress during back-side grinding of the wafer, and to a method for manufacturing a semiconductor device using the adhesive tape. [Background technology]

[0002] As various electronic devices become smaller and more multifunctional, the semiconductor chips mounted on them are also required to be smaller and thinner. To thin chips, it is common to adjust the thickness by grinding the back surface of the semiconductor wafer. In addition, to obtain thin chips, a method called Dicing Before Grinding (DBG) is sometimes used, in which grooves of a predetermined depth are formed from the front side of the wafer using a dicing blade, and then the back side of the wafer is ground to separate the wafer into individual chips through grinding. DBG allows for the simultaneous grinding of the back surface of the wafer and the separation of the wafer into individual chips, thus enabling the efficient manufacture of thin chips.

[0003] In recent years, a variation of the pre-dicing method has been proposed in which a modified region is created inside the wafer using a laser, and the wafer is fragmented by stress during back-side grinding. Hereafter, this method may be referred to as LDBG (Laser Dicing Before Grinding). In LDBG, the wafer is cut in the crystal direction starting from the modified region, so the occurrence of chipping can be reduced compared to the pre-dicing method using a dicing blade. As a result, chips with excellent flexural strength can be obtained, and it can also contribute to further thinning of the chips. Furthermore, compared to DBG, which forms grooves of a predetermined depth on the wafer surface with a dicing blade, there is no region where the wafer is scraped off by the dicing blade, meaning that the kerf width is extremely small, resulting in superior chip yield.

[0004] Conventionally, during back-grinding of semiconductor wafers and during chip manufacturing using DBG or LDBG, it is common practice to apply an adhesive tape called a backgrind sheet to the wafer surface to protect the circuits on the wafer surface and to hold the semiconductor wafer and semiconductor chip in place. After back-grinding, an adhesive tape with an adhesive layer is applied to the ground surface. Subsequently, the adhesive tape applied to the wafer surface is peeled off after its adhesive strength is reduced by irradiation with energy rays such as ultraviolet light. Through this process, adhesive tape is applied to the back surface of the wafer.

[0005] Here, Patent Document 1 proposes an adhesive tape having an adhesive layer using an adhesive in which the tack force reduction rate after ultraviolet irradiation in the presence of oxygen is 60% or more. However, when using the tape described in Patent Document 1, if the finished thickness of the chip is thinned to about 30 μm, chipping or damage to the chip (hereinafter sometimes referred to as "chip cracking") may occur when peeling off the adhesive tape. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-185691 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As a result of diligent research to solve the above problems, the inventors of the present invention discovered that, due to the reduced thickness of the semiconductor wafer after grinding, there are regions where the adhesive strength does not sufficiently decrease even when irradiated with energy rays such as ultraviolet light on the adhesive tape, and cracks occur in the chip when the adhesive tape is peeled off.

[0008] FIG. 1 is a schematic diagram showing the state in which the thickness of the semiconductor wafer 20 gradually decreases when the back surface of the semiconductor wafer 20 with the adhesive tape 10 attached is ground. In FIG. 1, (1) shows the state before back grinding, (3) shows the state when the thickness of the semiconductor wafer is about 30 μm, and (2) shows the state during the process from (1) to (3). Usually, as shown in FIG. 1(1), the side surface of the semiconductor wafer 20 before grinding is rounded. The adhesive tape 10 protects the circuit on the wafer surface and contains a flat and hard material that can usually hold the wafer and chips. Therefore, when the adhesive tape 10 is attached to the wafer 20 before grinding, as shown in FIG. 1(1), a slightly non-adhesive area occurs at the outer edge of the wafer 20.

[0009] As shown in FIG. 1, as the back grinding of the semiconductor wafer 20 progresses for (1), (2), and (3), the thickness of the semiconductor wafer 20 decreases and the size also changes, but the size of the adhesive tape 10 does not change. Then, when the wafer is back ground to an extremely thin thickness of about 30 μm, as shown in FIG. 1(3), the rounded portion on the side surface of the wafer 20 is removed. Then, even if the shape of the adhesive tape is made substantially the same as that of the wafer before grinding as in FIG. 1(1), after grinding, the outer edge of the adhesive tape 10 is exposed at the outer peripheral portion of the wafer 20 as shown in FIG. 1(3). When the adhesive tape is irradiated with an energy ray such as ultraviolet light in this state, the adhesive force sufficiently decreases in the portion where the adhesive tape is in close contact with the wafer. However, in the portion of the adhesive tape that is not in close contact with the wafer and is exposed to the atmosphere (the exposed portion at the outer edge), the curing of the adhesive is inhibited by oxygen in the atmosphere, and the adhesive force does not sufficiently decrease even by irradiation with an energy ray such as ultraviolet light. That is, the adhesive tape has an uncured portion even after irradiation with an energy ray such as ultraviolet light.

[0010] After back-grinding, a dicing-die bonding tape is applied to the back surface of the wafer, for example, as an adhesive tape. Figures 2 and 3 are schematic diagrams of a laminate in which a dicing-die bonding tape 30 is further applied to a semiconductor wafer 20 that has been back-grinded and to which an adhesive tape 10 has been applied. The dicing-die bonding tape 30 includes an adhesive layer (not shown), and is attached to the semiconductor wafer 20 by this adhesive layer. Figure 3 shows a semiconductor wafer 20 that has been back-grinded to an extremely thin thickness of about 30 μm with the dicing-die bonding tape 30 applied to it. On the other hand, Figure 2 shows a semiconductor wafer 20 with the dicing-die bonding tape 30 applied, where the thickness of the semiconductor wafer 20 is greater than that shown in Figure 3. As shown in Figure 2, when the thickness of the semiconductor wafer 20 after back-grinding is greater, even if the dicing-die bonding tape 30 is applied, the uncured portion of the adhesive tape 10 does not come into contact with the adhesive layer of the dicing-die bonding tape 30. However, as shown in Figure 3, when the thickness of the semiconductor wafer 20 after back grinding is reduced to an extremely thin 30 μm, there is a risk that the uncured portion of the adhesive tape 10 will come into contact with the adhesive layer of the dicing / die bonding tape 30 and stick to it when the dicing / die bonding tape 30 is applied. The dicing / die bonding tape is not cut like a wafer. Therefore, when attempting to peel off the adhesive tape that has adhered to the dicing / die bonding tape, the adhesive tape and the dicing / die bonding tape become one, and the dicing / die bonding tape bends along with the bending of the adhesive tape. The wafer or chip sandwiched between the adhesive tape and the dicing / die bonding tape also bends simultaneously. As a result, cracks are more likely to occur in the chip. In addition, the adhesive layer of the dicing / die bonding tape may be damaged by the bending, and fragments may fall off.

[0011] In other words, when the adhesive tape is irradiated with energy rays such as ultraviolet light, there are areas where the adhesive strength does not decrease sufficiently. This poses a problem because, when the thickness of a semiconductor wafer is made extremely thin by back grinding, chip cracks are more likely to occur when the adhesive tape is peeled off.

[0012] The present invention has been made in view of the above-described prior art, and an object thereof is to provide an adhesive tape for semiconductor processing that can suppress cracking of a chip when peeling the adhesive tape.

Means for Solving the Problems

[0013] The gist of the present invention for solving such problems is as follows.

[0014] (1) An adhesive tape having a base material and an adhesive layer, with one surface of the adhesive layer exposed to an air atmosphere, an illuminance of 220 mW / cm 2 and a light quantity of 5*10^2 mJ / cm 2 After irradiating the adhesive tape with ultraviolet rays under the conditions of, the surface elastic modulus of the exposed surface of the adhesive layer is 5 MPa or more, an adhesive tape for semiconductor processing.

[0015] (2) The adhesive layer contains an acrylic resin, The adhesive tape for semiconductor processing according to (1), wherein the content of the polymerization unit derived from HEMA is 6 parts by mass or more with respect to 100 parts by mass of the total amount of the acrylic resin.

[0016] (3) With one surface of the adhesive layer exposed to an air atmosphere, an illuminance of 220 mW / cm 2 and a light quantity of 5*10^2 mJ / cm 2 After irradiating the adhesive tape with ultraviolet rays under the conditions of, the surface free energy of the exposed surface of the adhesive layer is less than 36 mJ / m 2 The adhesive tape for semiconductor processing according to (1) or (2).

[0017] (4) A step of attaching the adhesive tape for semiconductor processing according to any one of (1) to (3) to the surface of a semiconductor wafer and cutting the adhesive tape along the outer periphery of the semiconductor wafer; A step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer; A step of grinding a semiconductor wafer on which the adhesive tape is attached to the surface and on which the groove or modified region is formed, from the back side to separate it into multiple chips starting from the groove or modified region, The process of peeling the adhesive tape from the plurality of chips, A method for manufacturing a semiconductor device comprising the same equipment.

[0018] (5) The method for manufacturing a semiconductor device according to (4), further comprising the step of attaching a dicing die bonding tape to the back surface of a semiconductor wafer. [Effects of the Invention]

[0019] The adhesive tape for semiconductor processing according to the present invention can sufficiently reduce the adhesive strength of the adhesive layer in an atmospheric environment. As a result, the occurrence of cracks in semiconductor chips can be suppressed. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram showing the process of backside grinding of a semiconductor wafer. [Figure 2] Figure 2 is a schematic diagram of a laminate consisting of adhesive tape 10, a semiconductor wafer 20 after backside grinding, and dicing / die bonding tape 30, showing the case where the thickness of the semiconductor wafer 20 is greater than that shown in Figure 3. [Figure 3] Figure 3 is a schematic diagram of a laminate consisting of adhesive tape 10, a semiconductor wafer 20 after backside grinding, and dicing / die bonding tape 30, showing the semiconductor wafer 20 being backside ground to a thickness of approximately 30 μm. [Figure 4] Figure 4 is a schematic diagram showing the adhesive tape according to this embodiment. [Figure 5] Figure 5 is a schematic diagram of a laminate comprising an adhesive tape, a semiconductor wafer 20 after backside grinding, and a dicing / die bonding tape 30 according to this embodiment, showing the case where the semiconductor wafer 20 has been backside ground to a thickness of approximately 30 μm. [Modes for carrying out the invention]

[0021] The adhesive tape for semiconductor processing according to the present invention will be described in detail below. First, the main terms used in this specification will be explained. In this specification, for example, "(meth)acrylate" is used to refer to both "acrylate" and "methacrylate," and the same applies to other similar terms.

[0022] "For semiconductor processing" means that it can be used in various processes such as semiconductor wafer transport, back grinding, dicing, and semiconductor chip pickup. The "front side" of a semiconductor wafer refers to the side on which circuits are formed, while the "back side" refers to the side on which no circuits are formed. Semiconductor wafer fragmentation refers to the process of dividing a semiconductor wafer into individual circuits to obtain semiconductor chips.

[0023] DBG refers to a method of wafer fragmentation by forming grooves of a predetermined depth on the surface side of a wafer, and then grinding from the back side of the wafer. The grooves formed on the surface side of the wafer are formed by methods such as blade dicing, laser dicing, and plasma dicing. LDBG is a variation of DBG, in which a modified region is created inside the wafer using a laser, and the wafer is fragmented by the stress during back-side grinding.

[0024] Next, the configuration of each component of the semiconductor processing adhesive tape according to the present invention will be described in more detail. Note that the semiconductor processing adhesive tape according to the present invention may sometimes be simply referred to as "adhesive tape."

[0025] In this embodiment, as shown in Figure 4, the adhesive tape 100 refers to a laminate comprising a base material 110 and an adhesive layer 120. The adhesive tape 100 may have a buffer layer on at least one surface of the base material 110. However, this does not prevent the inclusion of other constituent layers. For example, a primer layer may be formed on the surface of the base material on the adhesive layer side, and a release sheet may be laminated on the surface of the adhesive layer to protect the adhesive layer until use. The base material may be a single layer or a multilayer. The same applies to the adhesive layer and the buffer layer. The configuration of each component of the adhesive tape for semiconductor processing according to this embodiment will be described in more detail below.

[0026] ○ Adhesive layer In the adhesive tape according to this embodiment, with one surface of the adhesive layer exposed to an atmospheric environment, the illuminance is 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 After irradiating the adhesive tape with ultraviolet light under these conditions, the surface modulus of the exposed surface of the adhesive layer is 5 MPa or more, preferably 6 MPa or more, and more preferably 6.5 MPa or more. By setting the surface modulus within the above range, the adhesive strength of the adhesive layer can be sufficiently reduced, and as a result, the occurrence of cracks in the chip can be suppressed. Furthermore, there is no particular upper limit to the surface modulus, but it is usually 17 MPa, and preferably 14 MPa.

[0027] In the measurement of the surface modulus described above, ultraviolet irradiation is performed from the substrate side. The surface modulus is measured using an atomic force microscope. Specifically, a silicon nitride cantilever (tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4 N / m) is placed on the atomic force microscope and pressed against the surface of the adhesive layer at room temperature with a pressing depth of 5 nm and a scanning speed of 5 Hz, then pulled back. The resulting force curve (horizontal axis is the amount of sample deformation, vertical axis is the measured load) is fitted to the JKR theoretical formula to calculate the surface modulus. The average value obtained from measurements at 4096 points within a 5 μm × 5 μm area of ​​the adhesive layer surface is taken as the surface modulus (MPa).

[0028] The surface elastic modulus can be controlled by preparing the adhesive layer so that it contains an acrylic resin and further adjusting the amount of polymerization units derived from 2-hydroxyethyl methacrylate (hereinafter sometimes abbreviated as HEMA). In particular, the surface elastic modulus can be controlled within the above range by preparing the adhesive layer so that the content of polymerization units derived from HEMA is 6 parts by mass or more with respect to 100 parts by mass of the total amount of the acrylic resin.

[0029] In the adhesive tape according to the present embodiment, with one surface of the adhesive layer exposed to the atmosphere, the surface free energy of the exposed surface of the adhesive layer after irradiating the adhesive tape with ultraviolet rays under the conditions of an illuminance of 220 mW / cm 2 and a light amount of 500 mJ / cm 2 is preferably less than 36 mJ / m 2 , more preferably less than 32 mJ / m 2 , and preferably less than 30 mJ / m 2 . From the viewpoint of sufficiently reducing the adhesive force of the adhesive layer, it is preferable that the surface free energy is within the above range. Also, the lower limit of the surface free energy is not particularly limited, but is usually 18 mJ / m 2 , and preferably 22 mJ / m 2 .

[0030] In the measurement of the surface free energy, the ultraviolet rays are irradiated from the substrate side. Also, the surface free energy is obtained by measuring the contact angles of various droplets (measurement temperature: 25°C) and based on the values of the contact angles by the Kitazaki-Hata method. Specifically, diiodomethane, 1-bromonaphthalene, and distilled water are used as droplets, and the contact angles (measurement temperature: 25°C) are measured by the sessile drop method in accordance with JIS R 3257:1999, and based on the values of the contact angles, the surface free energy (mJ / m 2 ) is obtained.

[0031] The above surface free energy can be controlled by preparing the adhesive layer to contain an acrylic resin and further adjusting the amount of HEMA-derived polymerization units. In particular, the surface free energy can be controlled within the above range by preparing the adhesive layer so that the HEMA-derived polymerization unit content is 6 parts by mass or more per 100 parts by mass of the total amount of acrylic resin.

[0032] Furthermore, in the adhesive tape according to this embodiment, with one surface of the adhesive layer exposed to an atmospheric environment, the illuminance is 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 When the adhesive tape is irradiated with ultraviolet light under the specified conditions, and a PMMA board is attached to the exposed surface of the adhesive layer at 23°C and 50%RH using a 2kg roll for one pass-through, and left for 30 minutes, the peel strength when the adhesive tape is peeled off at 180° is preferably 1600mN / 25mm or less, more preferably 1100mN / 25mm or less, even more preferably 980mN / 25mm or less, and particularly preferably 800mN / 25mm or less. From the viewpoint of sufficiently reducing the adhesive strength of the adhesive layer, it is preferable to set the peel strength within the above range. Furthermore, the lower limit of the peel strength is not particularly limited, but is usually 50N / 25mm, and preferably 80N / 25mm.

[0033] In the measurement of the peel strength described above, ultraviolet irradiation is performed from the substrate side. PMMA refers to polymethyl methacrylate, and the PMMA plate used is "Acrylite L001" manufactured by Mitsubishi Chemical Corporation, with a thickness of 2 mm, a width of 70 mm, and a length of 150 mm. The peel strength is measured under the conditions of an adhesive tape width of 25 mm, a peeling speed of 300 mm / min, and a measurement temperature of 25°C, and the average value obtained by repeating the measurement under the same conditions twice is taken as the peel strength.

[0034] The above peel strength can be controlled by preparing the adhesive layer to contain an acrylic resin and further adjusting the amount of HEMA-derived polymerization units. In particular, the peel strength can be controlled within the above range by preparing the adhesive layer so that the HEMA-derived polymerization unit content is 6 parts by mass or more per 100 parts by mass of the total amount of acrylic resin.

[0035] Furthermore, in the adhesive tape according to this embodiment, with one surface of the adhesive layer exposed to an atmospheric environment, the illuminance is 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 The adhesion energy of the exposed surface of the adhesive layer after irradiating the adhesive tape with ultraviolet light under these conditions is preferably 0.220 J / m 2 The following, and more preferably 0.200 J / m³ 2 The following, and more preferably 0.190 J / m³ 2 The following applies. From the viewpoint of sufficiently reducing the adhesive strength of the adhesive layer, it is preferable that the adhesion energy be within the above range. Furthermore, the lower limit of the adhesion energy is not particularly limited, but is usually 0.12 J / m 2 The preferred concentration is 0.14 J / m³. 2 That is the case.

[0036] In the above measurement of adhesion energy, ultraviolet irradiation is performed from the substrate side. Furthermore, the adhesion energy is measured using an atomic force microscope. Specifically, a silicon nitride cantilever (tip radius: 2 nm, resonance frequency: 70 kHz, spring constant: 0.4 N / m) mounted on the atomic force microscope is used to press and pull the surface of the adhesive layer at room temperature with a pressing depth of 5 nm and a scanning speed of 5 Hz. The resulting force curve (horizontal axis is sample deformation, vertical axis is measured load) is fitted to the JKR theoretical formula to calculate the adhesion energy. The average value obtained from measurements at 4096 points within a 5 μm × 5 μm area of ​​the adhesive layer surface is used to calculate the adhesion energy (J / m²). 2 )

[0037] The above adhesion energy can be controlled by preparing the adhesive layer to contain an acrylic resin and further adjusting the amount of HEMA-derived polymerization units. In particular, the adhesion energy can be controlled within the above range by preparing the adhesive layer so that the HEMA-derived polymerization unit content is 6 parts by mass or more per 100 parts by mass of the total amount of acrylic resin.

[0038] The thickness of the adhesive layer is not particularly limited as long as the peel strength after ultraviolet irradiation in an atmospheric environment is 1600 mN / 25 mm or less, as described above, but is preferably less than 100 μm, more preferably 5 to 80 μm, and even more preferably 10 to 70 μm.

[0039] Furthermore, the adhesive layer is not particularly limited as long as its peel strength after UV irradiation in an atmospheric environment is 1600 mN / 25 mm or less, as described above, but it is preferably formed from an acrylic adhesive. Also, the adhesive layer is preferably formed from an energy-ray curable adhesive. "Energy rays" refer to ultraviolet rays, electron beams, etc., and ultraviolet rays are preferably used.

[0040] The following describes specific examples of adhesives, but these are non-limiting examples, and the adhesive layer in the present invention should not be interpreted as being limited to these examples.

[0041] [Adhesive composition] As the energy-ray curable adhesive that forms the adhesive layer, for example, an energy-ray curable adhesive composition containing an energy-ray curable compound other than the adhesive resin (hereinafter also referred to as "Type X adhesive composition") can be used in addition to a non-energy-ray curable adhesive resin (also referred to as "adhesive resin I"). Furthermore, an adhesive composition containing an energy-ray curable adhesive resin (hereinafter also referred to as "adhesive resin II") in which an unsaturated group is introduced into the side chain of a non-energy-ray curable adhesive resin as the main component, and which does not contain any energy-ray curable compounds other than the adhesive resin (hereinafter also referred to as "Type Y adhesive composition") may also be used.

[0042] Furthermore, as an energy-ray curable adhesive, a combination of type X and type Y, that is, an energy-ray curable adhesive composition (hereinafter also referred to as "XY-type adhesive composition") which includes an energy-ray curable adhesive resin II as well as an energy-ray curable compound other than the adhesive resin, may also be used. Among these, it is preferable to use an XY-type adhesive composition. By using an XY-type composition, it is possible to have sufficient adhesive properties before curing, while keeping the peel strength to the semiconductor wafer sufficiently low after curing.

[0043] However, the adhesive may be formed from a non-energy-ray curable adhesive composition that does not harden when irradiated with energy rays. The non-energy-ray curable adhesive composition contains at least a non-energy-ray curable adhesive resin I, but does not contain the above-mentioned energy-ray curable adhesive resin II or energy-ray curable compound.

[0044] In the following explanation, "adhesive resin" is used as a term referring to either or both of the above-mentioned adhesive resins I and II. Specific examples of adhesive resins include acrylic resins, urethane resins, rubber resins, and silicone resins, but acrylic resins are preferred. The following provides a more detailed explanation of acrylic adhesives, specifically those using acrylic resins as the adhesive resin.

[0045] Acrylic resins utilize acrylic polymers. Acrylic polymers are obtained by polymerizing monomers containing at least alkyl (meth)acrylate, and include constituent units derived from alkyl (meth)acrylate. Examples of alkyl (meth)acrylates include alkyl groups with 1 to 20 carbon atoms, and the alkyl group may be linear or branched. Specific examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Alkyl (meth)acrylates may be used alone or in combination of two or more types.

[0046] Furthermore, from the viewpoint of improving the adhesive strength of the adhesive layer, the acrylic polymer preferably contains constituent units derived from alkyl (meth)acrylate, in which the alkyl group has 4 or more carbon atoms. The number of carbon atoms in the alkyl (meth)acrylate is preferably 4 to 12, and more preferably 4 to 6. In addition, the alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms is preferably an alkyl acrylate.

[0047] In the acrylic polymer, the content of alkyl (meth)acrylate having 4 or more carbon atoms in the alkyl group is preferably 35 to 98 parts by mass, more preferably 45 to 95 parts by mass, and even more preferably 50 to 90 parts by mass, per 100 parts by mass of the total amount of monomers constituting the acrylic polymer (hereinafter also simply referred to as "total amount of monomers").

[0048] The acrylic polymer is preferably a copolymer that includes structural units derived from alkyl(meth)acrylate having 4 or more carbon atoms in the alkyl group, as well as structural units derived from alkyl(meth)acrylate having 1 to 3 carbon atoms in the alkyl group, in order to adjust the elastic modulus and adhesive properties of the adhesive layer. The alkyl(meth)acrylate is preferably an alkyl(meth)acrylate having 1 or 2 carbon atoms, more preferably methyl(meth)acrylate, and most preferably methyl methacrylate. In the acrylic polymer, the content of alkyl(meth)acrylate having 1 to 3 carbon atoms in the alkyl group is preferably 1 to 30 parts by mass, more preferably 3 to 26 parts by mass, and even more preferably 5 to 22 parts by mass, per 100 parts by mass of the total amount of monomer.

[0049] It is preferable that the acrylic polymer has structural units derived from functional group-containing monomers in addition to the alkyl (meth)acrylate-derived structural units described above. Examples of functional groups in the functional group-containing monomers include hydroxyl groups, carboxyl groups, amino groups, epoxy groups, etc. The functional group-containing monomer can react with the crosslinking agent described later to become a crosslinking starting point, or react with the unsaturated group-containing compound to introduce unsaturated groups into the side chains of the acrylic polymer.

[0050] Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and the like. In this embodiment, it is particularly preferable to use HEMA in an amount greater than or equal to a predetermined amount as the functional group-containing monomer.

[0051] In the adhesive tape according to this embodiment, the adhesive layer contains an acrylic resin, and it is preferable that the content of HEMA-derived polymerization units is 6 parts by mass or more per 100 parts by mass of the total amount of acrylic resin. The content of HEMA-derived polymerization units can further be 10 parts by mass or more, or 12 parts by mass or more. By using the above range for the content of HEMA-derived polymerization units in the preparation of the adhesive layer, the peel strength, surface free energy, surface modulus, and adhesion energy of the adhesive can be set to a desired range. Furthermore, there is no particular upper limit to the content of HEMA-derived polymerization units in the adhesive layer, but it is usually 35 parts by mass, preferably 32 parts by mass, per 100 parts by mass of the total amount of acrylic resin.

[0052] In this embodiment, hydroxyl group-containing monomers other than HEMA, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, etc., may be used individually or in combination of two or more. Among these, the use of hydroxyl group-containing monomers and carboxyl group-containing monomers is preferred, and the use of hydroxyl group-containing monomers is more preferred.

[0053] Examples of hydroxyl group-containing monomers include, in addition to HEMA mentioned above, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0054] Examples of monomers containing a carboxyl group include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid, and their anhydrides, as well as 2-carboxyethyl methacrylate.

[0055] The content of functional group-containing monomers other than HEMA is preferably 1 to 35 parts by mass, more preferably 3 to 32 parts by mass, and even more preferably 6 to 30 parts by mass, based on 100 parts by mass of the total amount of monomers constituting the acrylic polymer. Furthermore, the acrylic polymer may also contain monomer-derived structural units that can copolymerize with the above-mentioned acrylic monomers, such as styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

[0056] The above-mentioned acrylic polymer can be used as a non-energy ray curable adhesive resin I (acrylic resin). Furthermore, an example of an energy ray curable acrylic resin is obtained by reacting the functional groups of the above-mentioned acrylic polymer I with a compound having a photopolymerizable unsaturated group (also called an unsaturated group-containing compound).

[0057] Unsaturated group-containing compounds are compounds that have both substituents that can be bonded to the functional groups of acrylic polymers and photopolymerizable unsaturated groups. Examples of photopolymerizable unsaturated groups include (meth)acryloyl groups, vinyl groups, allyl groups, and vinylbenzyl groups, with (meth)acryloyl groups being preferred. Furthermore, substituents that can be bonded to functional groups in unsaturated group-containing compounds include isocyanate groups and glycidyl groups. Therefore, examples of unsaturated group-containing compounds include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

[0058] Furthermore, the unsaturated group-containing compound preferably reacts with some of the functional groups of the acrylic polymer. Specifically, it is preferable to react 50 to 98 mol% of the functional groups of the acrylic polymer with the unsaturated group-containing compound, and more preferably 55 to 93 mol%. In this way, in the energy-ray curable acrylic resin, some of the functional groups remain without reacting with the unsaturated group-containing compound, making it easier to crosslink with a crosslinking agent. The weight-average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1,600,000, more preferably 400,000 to 1,400,000, and even more preferably 500,000 to 1,200,000.

[0059] (Energy ray curable compound) As the energy-curable compound contained in the X-type or XY-type adhesive composition, monomers or oligomers having an unsaturated group in the molecule and capable of polymerization curing by energy irradiation are preferred. Examples of such energy-ray curable compounds include polyvalent (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate, as well as oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate.

[0060] Among these, urethane (meth)acrylate oligomers are preferred because they have a relatively high molecular weight and do not easily reduce the shear storage modulus of the adhesive layer. The molecular weight (weight-average molecular weight in the case of oligomers) of the energy ray-curable compound is preferably 100 to 12000, more preferably 200 to 10000, even more preferably 400 to 8000, and particularly preferably 600 to 6000.

[0061] The content of the energy ray curable compound in the X-type adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and even more preferably 60 to 90 parts by mass, per 100 parts by mass of adhesive resin. On the other hand, the content of the energy-ray curable compound in the XY-type adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and even more preferably 3 to 15 parts by mass, per 100 parts by mass of the adhesive resin. In the XY-type adhesive composition, since the adhesive resin is energy-ray curable, it is possible to sufficiently reduce the peel strength after energy-ray irradiation even with a small content of the energy-ray curable compound.

[0062] (Crosslinking agent) The adhesive composition preferably further contains a crosslinking agent. The crosslinking agent crosslinks the adhesive resins by reacting with, for example, functional groups derived from functional group-containing monomers of the adhesive resin. Examples of crosslinking agents include isocyanate-based crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy-based crosslinking agents such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphotriazine; and chelate-based crosslinking agents such as aluminum chelate. These crosslinking agents may be used individually or in combination of two or more.

[0063] Among these, isocyanate-based crosslinking agents are preferred from the viewpoint of increasing cohesive force and improving adhesiveness, as well as from the viewpoint of ease of availability. From the viewpoint of promoting the crosslinking reaction, the amount of crosslinking agent added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass, per 100 parts by mass of adhesive resin.

[0064] (Photopolymerization initiator) Furthermore, if the adhesive composition is energy-ray curable, it is preferable that the adhesive composition further contains a photopolymerization initiator. By including a photopolymerization initiator, the curing reaction of the adhesive composition can proceed sufficiently even with relatively low-energy energy rays such as ultraviolet light.

[0065] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,2-dimethoxy-2-phenylacetophenone.

[0066] These photopolymerization initiators may be used individually or in combination of two or more. The amount of photopolymerization initiator added is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 5 parts by mass, per 100 parts by mass of adhesive resin.

[0067] (Other additives) The adhesive composition may contain other additives as long as they do not impair the effects of the present invention. Examples of other additives include antistatic agents, antioxidants, plasticizers, fillers, rust inhibitors, pigments, dyes, and the like. When these additives are included, the amount of additive is preferably 0.01 to 6 parts by mass per 100 parts by mass of the adhesive resin.

[0068] Furthermore, the adhesive composition may be further diluted with an organic solvent to provide a solution, from the viewpoint of improving its applicability to substrates, buffer layers, and release sheets. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. These organic solvents may be the same organic solvents used during the synthesis of the adhesive resin, or one or more organic solvents other than those used during synthesis may be added to ensure uniform application of the adhesive composition solution.

[0069] 〇Base material The substrate preferably has a Young's modulus of 1000 MPa or higher at 23°C. If a substrate with a Young's modulus of less than 1000 MPa is used, the holding performance of the adhesive tape against the semiconductor wafer or semiconductor chip will decrease, making it difficult to suppress vibrations during backside grinding, and increasing the likelihood of chipping or damage to the semiconductor chip. On the other hand, by setting the Young's modulus of the substrate to 1000 MPa or higher at 23°C, the holding performance of the adhesive tape against the semiconductor wafer or semiconductor chip will be improved, suppressing vibrations during backside grinding and preventing chipping or damage to the semiconductor chip. Furthermore, it will be possible to reduce the stress when peeling the adhesive tape from the semiconductor chip, preventing chipping or damage to the chip that occurs when peeling the tape. In addition, it will be possible to improve the workability when attaching the adhesive tape to the semiconductor wafer. From these viewpoints, the Young's modulus of the substrate at 23°C is more preferably 1800 to 30000 MPa, and even more preferably 2500 to 6000 MPa.

[0070] The thickness of the substrate is not particularly limited, but is preferably 110 μm or less, more preferably 15 to 110 μm, and even more preferably 20 to 105 μm. By making the substrate thickness 110 μm or less, it becomes easier to control the peel strength of the adhesive tape. Also, by making it 15 μm or more, the substrate can more easily function as a support for the adhesive tape.

[0071] The material of the base material is not particularly limited as long as it satisfies the above physical properties, and various resin films can be used. Examples of base materials with a Young's modulus of 1000 MPa or more at 23°C include resin films such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyesters such as fully aromatic polyesters, polyimides, polyamides, polycarbonates, polyacetals, modified polyphenylene oxide, polyphenylene sulfide, polysulfones, polyether ketones, and biaxially oriented polypropylene. Among these resin films, films containing one or more selected from polyester film, polyamide film, polyimide film, and biaxially oriented polypropylene film are preferred, more preferably containing polyester film, and even more preferably containing polyethylene terephthalate film.

[0072] Furthermore, the substrate may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc., to the extent that they do not impair the effects of the present invention. The substrate may also be transparent or opaque, and may be colored or vapor-deposited as desired. Furthermore, at least one surface of the substrate may be subjected to an adhesive treatment such as corona treatment to improve adhesion with at least one of the buffer layer and the adhesive layer. The substrate may also consist of the resin film described above and an easy-adhesion layer coated on at least one surface of the resin film.

[0073] The composition for forming an easily adhesive layer is not particularly limited, but examples include compositions containing polyester resins, urethane resins, polyester-urethane resins, acrylic resins, etc. The composition for forming an easily adhesive layer may optionally contain crosslinking agents, photopolymerization initiators, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, etc. The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. In this embodiment, the thickness of the easy-adhesion layer is small compared to the thickness of the substrate, so the thickness of the resin film with the easy-adhesion layer is substantially the same as the thickness of the substrate. Furthermore, because the material of the easy-adhesion layer is soft, it has little effect on the Young's modulus, and the Young's modulus of the substrate is substantially the same as that of the resin film, even when the easy-adhesion layer is present.

[0074] For example, the Young's modulus of a substrate can be controlled by selecting the resin composition, adding plasticizers, and the stretching conditions during resin film manufacturing. Specifically, when polyethylene terephthalate film is used as the substrate, the Young's modulus of the substrate tends to decrease as the proportion of ethylene in the copolymer increases. Also, the Young's modulus of the substrate tends to decrease as the amount of plasticizer added to the resin composition constituting the substrate increases.

[0075] 〇Buffer layer The adhesive tape according to this embodiment may have a buffer layer. The buffer layer can be provided on at least one surface of the substrate, or on both surfaces of the substrate. Alternatively, an adhesive layer can be provided on one surface of the substrate, and a buffer layer on the other surface of the substrate.

[0076] The buffer layer relieves stress during back-side grinding of the semiconductor wafer, preventing cracks and chips from occurring. When adhesive tape is applied to a semiconductor wafer and the tape is cut along the outer edge, the semiconductor wafer is placed on a chuck table via the adhesive tape and back-side grinding is performed. The presence of a buffer layer as a constituent layer of the adhesive tape makes it easier to properly hold the semiconductor wafer on the chuck table.

[0077] The buffer layer is a softer layer compared to the substrate. Therefore, the Young's modulus of the buffer layer at 23°C is smaller than that of the substrate at 23°C. Specifically, the Young's modulus of the buffer layer at 23°C is preferably less than 1000 MPa, more preferably 700 MPa or less, and even more preferably 500 MPa or less.

[0078] The thickness of the buffer layer is preferably 1 to 100 μm, more preferably 5 to 80 μm, and even more preferably 10 to 60 μm. By setting the thickness of the buffer layer within the above range, the buffer layer can appropriately relieve stress during backside grinding.

[0079] The buffer layer is preferably a cured product of a buffer layer-forming composition containing an energy ray polymerizable compound. It may also be a layer containing a polyolefin resin film, or a layer mainly composed of a polyether. The following describes, in order, each component contained in the layer formed from the buffer layer-forming composition containing an energy ray polymerizable compound, and each component contained in the layer containing a polyolefin resin film.

[0080] <Layer formed from a buffer layer-forming composition containing an energy-polymerizable compound> A buffer layer-forming composition containing an energy-ray polymerizable compound can be cured by irradiation with energy rays. Furthermore, the buffer layer-forming composition containing an energy-ray polymerizable compound more preferably contains urethane (meth)acrylate (a1). More preferably, the buffer layer-forming composition contains, in addition to (a1), a polymerizable compound (a2) having an alicyclic or heterocyclic group with 6 to 20 ring-forming atoms and / or a polymerizable compound (a3) ​​having a functional group. In addition, the buffer layer-forming composition may contain a polyfunctional polymerizable compound (a4) in addition to the components (a1) to (a3). Furthermore, the buffer layer-forming composition preferably contains a photopolymerization initiator, and may contain other additives and resin components to the extent that they do not impair the effects of the present invention. The following describes in detail each component contained in the buffer layer-forming composition containing energy ray polymerizable compounds.

[0081] (Urethane (meth)acrylate (a1)) Urethane (meth)acrylate (a1) is a compound having at least a (meth)acryloyl group and a urethane bond, and possessing the property of polymerization curing by energy ray irradiation. Urethane (meth)acrylate (a1) is an oligomer or polymer.

[0082] The weight-average molecular weight (Mw) of component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and even more preferably 10,000 to 30,000. The number of (meth)acryloyl groups in component (a1) (hereinafter also referred to as "number of functional groups") may be monofunctional, difunctional, or trifunctional or more, but monofunctional or difunctional is preferred. Component (a1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer, which is obtained by reacting a polyol compound with a polyvalent isocyanate compound, with a (meth)acrylate having a hydroxyl group. Component (a1) may be used alone or in combination of two or more components.

[0083] The polyol compound used as a raw material for component (a1) is not particularly limited as long as it is a compound having two or more hydroxyl groups. Specific examples of polyol compounds include alkylenediols, polyether-type polyols, polyester-type polyols, and polycarbonate-type polyols. Among these, polyester-type polyols or polycarbonate-type polyols are preferred. The polyol compound may be a bifunctional diol, a trifunctional triol, or a polyol with four or more functions, but a bifunctional diol is preferred, and a polyester-type diol or a polycarbonate-type diol is more preferred.

[0084] Examples of polyvalent isocyanate compounds include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and ω,ω'-diisocyanate dimethylcyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate. Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferred.

[0085] A urethane (meth)acrylate (a1) can be obtained by reacting the above-mentioned polyol compound with a polyvalent isocyanate compound to obtain a terminal isocyanate urethane prepolymer, and then reacting the (meth)acrylate having a hydroxyl group with the (meth)acrylate having a hydroxyl group. The (meth)acrylate having a hydroxyl group is not particularly limited as long as it is a compound having at least one molecule containing both a hydroxyl group and a (meth)acryloyl group.

[0086] Specific examples of (meth)acrylates having a hydroxyl group include, for example, hydroxyalkyl (meth)acrylates such as 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, and polypropylene glycol mono(meth)acrylate; hydroxyl group-containing (meth)acrylamides such as N-methylol (meth)acrylamide; and reaction products obtained by reacting vinyl alcohol, vinyl phenol, and diglycidyl esters of bisphenol A with (meth)acrylic acid. Among these, hydroxyalkyl (meth)acrylate is preferred, and 2-hydroxyethyl (meth)acrylate is more preferred.

[0087] The conditions for reacting the terminal isocyanate urethane prepolymer and the (meth)acrylate having a hydroxyl group are preferably such that the reaction is carried out at 60-100°C for 1-4 hours in the presence of a solvent and catalyst, which may be added as needed. The content of component (a1) in the buffer layer forming composition is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition.

[0088] (a2) Polymerizable compounds having alicyclic or heterocyclic groups with 6 to 20 ring-forming atoms Component (a2) is a polymerizable compound having an alicyclic or heterocyclic group with 6 to 20 ring-forming atoms, and more preferably a compound having at least one (meth)acryloyl group, and more preferably a compound having one (meth)acryloyl group. By using component (a2), the film-forming properties of the resulting buffer layer-forming composition can be improved.

[0089] Although there is some overlap between the definition of component (a2) and the definition of component (a3) ​​described later, the overlapping portion is included in component (a3). For example, a compound having at least one (meth)acryloyl group, an alicyclic or heterocyclic group with 6 to 20 ring-forming atoms, and a functional group such as a hydroxyl group, epoxy group, amide group, or amino group is included in the definitions of both component (a2) and component (a3), but in this invention, such a compound is included in component (a3).

[0090] The number of ring-forming atoms in the alicyclic or heterocyclic group of component (a2) is preferably 6 to 20, more preferably 6 to 18, even more preferably 6 to 16, and particularly preferably 7 to 12. Examples of atoms that form the ring structure of the heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, sulfur atoms, and the like. The number of ring-forming atoms refers to the number of atoms that make up the ring itself in a compound with a ring-shaped structure. Atoms that do not form a ring (for example, hydrogen atoms bonded to ring-forming atoms) and atoms included in substituents when the ring is substituted by substituents are not included in the number of ring-forming atoms.

[0091] Specific components (a2) include, for example, alicyclic group-containing (meth)acrylates such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, and adamantane (meth)acrylate; heterocyclic group-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate; and the like. Furthermore, component (a2) may be used alone or in combination of two or more types. Among alicyclic group-containing (meth)acrylates, isobornyl (meth)acrylate is preferred, and among heterocyclic group-containing (meth)acrylates, tetrahydrofurfuryl (meth)acrylate is preferred.

[0092] The content of component (a2) in the buffer layer forming composition is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition.

[0093] (Polymerizable compound having a functional group (a3)) Component (a3) ​​is a polymerizable compound containing functional groups such as hydroxyl groups, epoxy groups, amide groups, and amino groups, and is more preferably a compound having at least one (meth)acryloyl group, and more preferably a compound having one (meth)acryloyl group. Component (a3) ​​has good compatibility with component (a1), making it easier to adjust the viscosity of the buffer layer-forming composition to an appropriate range. Furthermore, good buffering performance is achieved even with a relatively thin buffer layer. Examples of component (a3) ​​include hydroxyl group-containing (meth)acrylates, epoxy group-containing compounds, amide group-containing compounds, and amino group-containing (meth)acrylates.

[0094] Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, phenylhydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate. Examples of epoxy group-containing compounds include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether. Among these, epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate are preferred. Examples of amide group-containing compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide. Examples of amino group-containing (meth)acrylates include primary amino group-containing (meth)acrylates, secondary amino group-containing (meth)acrylates, and tertiary amino group-containing (meth)acrylates.

[0095] Among these, hydroxyl group-containing (meth)acrylates are preferred, and hydroxyl group-containing (meth)acrylates having an aromatic ring, such as phenylhydroxypropyl (meth)acrylate, are more preferred. Furthermore, component (a3) ​​may be used alone or in combination of two or more types.

[0096] The content of component (a3) ​​in the buffer layer forming composition is preferably 5 to 40 parts by mass, more preferably 7 to 35 parts by mass, and even more preferably 10 to 30 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition, in order to improve the film-forming properties of the buffer layer forming composition. Furthermore, the content ratio of component (a2) to component (a3) ​​in the buffer layer forming composition [(a2) / (a3)] is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, even more preferably 1.3 to 3.0, and particularly preferably 1.5 to 2.8.

[0097] (Polyfunctional polymerizable compound (a4)) A polyfunctional polymerizable compound is a compound having two or more photopolymerizable unsaturated groups. Photopolymerizable unsaturated groups are functional groups containing a carbon-carbon double bond, such as (meth)acryloyl groups, vinyl groups, allyl groups, and vinylbenzyl groups. Two or more types of photopolymerizable unsaturated groups may be combined. A three-dimensional network structure (crosslinked structure) is formed when a photopolymerizable unsaturated group in the polyfunctional polymerizable compound reacts with the (meth)acryloyl group in component (a1), or when photopolymerizable unsaturated groups in component (a4) react with each other. When using a polyfunctional polymerizable compound, the number of crosslinked structures formed by energy ray irradiation tends to increase compared to when using a compound containing only one photopolymerizable unsaturated group.

[0098] Note that there is some overlap between the definition of component (a4) and the definitions of components (a2) and (a3) ​​mentioned above, but the overlapping parts are included in component (a4). For example, a compound having an alicyclic or heterocyclic group with 6 to 20 ring-forming atoms and having two or more (meth)acryloyl groups is included in the definitions of both component (a4) and component (a2), but in this invention, such a compound is included in component (a4). Also, a compound containing a functional group such as a hydroxyl group, epoxy group, amide group, or amino group and having two or more (meth)acryloyl groups is included in the definitions of both component (a4) and component (a3), but in this invention, such a compound is included in component (a4).

[0099] From the above viewpoint, the number of photopolymerizable unsaturated groups (number of functional groups) in a polyfunctional polymerizable compound is preferably 2 to 10, and more preferably 3 to 6.

[0100] Furthermore, the weight-average molecular weight of component (a4) is preferably 30 to 40,000, more preferably 100 to 10,000, and even more preferably 200 to 1,000.

[0101] Specific components (a4) 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)acrylate Examples include luamide, etc. Furthermore, component (a4) may be used alone or in combination of two or more types. Among these, dipentaerythritol hexa(meth)acrylate is preferred.

[0102] The content of component (a4) in the buffer layer forming composition is preferably 2 to 40 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 5 to 15 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition.

[0103] (Polymerizable compounds other than components (a1) to (a4) (a5)) The buffer layer forming composition may also contain other polymerizable compounds (a5) other than the above components (a1) to (a4), as long as the effects of the present invention are not impaired. Examples of component (a5) include alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms; vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Component (a5) may be used alone or in combination of two or more.

[0104] The content of component (a5) in the buffer layer forming composition is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, even more preferably 0 to 5 parts by mass, and particularly preferably 0 to 2 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition.

[0105] (Photopolymerization initiator) The buffer layer forming composition preferably contains a photopolymerization initiator, from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the buffer layer.

[0106] Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0107] These photopolymerization initiators can be used individually or in combination of two or more.

[0108] The amount of photopolymerization initiator in the buffer layer-forming composition is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the total amount of energy ray polymerizable compounds.

[0109] (Other additives) The buffer layer forming composition may contain other additives as long as they do not impair the effects of the present invention. Examples of other additives include antistatic agents, antioxidants, plasticizers, fillers, rust inhibitors, pigments, dyes, and the like. When these additives are included, the amount of each additive in the buffer layer forming composition is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total amount of energy ray polymerizable compounds.

[0110] (Resin components) The buffer layer-forming composition may contain a resin component, to the extent that it does not impair the effects of the present invention. Examples of resin components include polyene-thiol resins, polyolefin resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene copolymers. The content of these resin components in the buffer layer forming composition is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, even more preferably 0 to 5 parts by mass, and particularly preferably 0 to 2 parts by mass, based on the total amount (100 parts by mass) of the buffer layer forming composition.

[0111] The buffer layer formed from a buffer layer-forming composition containing an energy-ray polymerizable compound is obtained by polymerizing and curing the buffer layer-forming composition of the above composition by energy-ray irradiation. In other words, the buffer layer is a cured product of the buffer layer-forming composition. Therefore, the buffer layer contains polymerization units derived from component (a1). Preferably, the buffer layer also contains polymerization units derived from component (a2) and / or component (a3). Furthermore, it may also contain polymerization units derived from component (a4) and / or component (a5). The content ratio of each polymerization unit in the buffer layer usually corresponds to the ratio (compounding ratio) of each component constituting the buffer layer forming composition. For example, if the content of component (a1) in the buffer layer forming composition is 10 to 70 parts by mass per 100 parts by mass of the total amount of the buffer layer forming composition, the buffer layer contains 10 to 70 parts by mass of polymerization units derived from component (a1). Similarly, if the content of component (a2) in the buffer layer forming composition is 10 to 80 parts by mass per 100 parts by mass of the total amount of the buffer layer forming composition, the buffer layer contains 10 to 80 parts by mass of polymerization units derived from component (a2). The same applies to components (a3) ​​to (a5).

[0112] <Layer containing polyolefin resin film> The buffer layer may be formed by a layer containing a polyolefin resin film.

[0113] When the buffer layer is a layer containing a polyolefin resin film, the stress relaxation properties may be lower than when the buffer layer is formed from a buffer layer-forming composition containing an energy-ray polymerizable compound. In this case, adhesive tapes having a buffer layer formed from a layer containing a polyolefin resin film on one side of the substrate may warp. While it is sufficient for the buffer layer formed from a layer containing a polyolefin resin film to be provided on at least one side of the substrate, from the viewpoint of preventing such problems, it is preferable that the buffer layer formed from a layer containing a polyolefin resin film be provided on both sides of the substrate.

[0114] The polyolefin resin is not particularly limited; for example, very low-density polyethylene (VLDPE, density: 880 kg / m³) 3 More than 910kg / m 3 (less than), low-density polyethylene (LDPE, density: 910 kg / m³) 3 More than 930kg / m 3(less than), medium-density polyethylene (MDPE, density: 930 kg / m³) 3 Above, 942kg / m 3 (less than), high-density polyethylene (HDPE, density: 942 kg / m³) 3 Examples include polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin-based elastomers (TPO), cycloolefin resins, ethylene-vinyl acetate copolymers (EVA), ethylene-vinyl acetate-maleic anhydride copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, and ethylene-(meth)acrylic acid ester-maleic anhydride copolymers. These polyolefin resins can be used individually or in combination of two or more types.

[0115] Among the polyolefin resins mentioned above, polyethylene resin is preferred, and low-density polyethylene is more preferred, from the viewpoint of obtaining a buffer layer with specific physical properties.

[0116] The buffer layer described above may contain additives such as plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, and catalysts, to the extent that they do not impair the effects of the present invention. Furthermore, the buffer layer described above may be transparent or opaque, and may be colored or vapor-deposited as desired.

[0117] ○ Release sheet A release liner may be attached to the surface of the adhesive tape. Specifically, the release liner is attached to the surface of the adhesive layer of the adhesive tape. The release liner protects the adhesive layer during transport and storage. The release liner is attached to the adhesive tape in a removable manner and is peeled off and removed from the adhesive tape before the adhesive tape is used (i.e., before wafer attachment). The release sheet used is one in which at least one side has been treated to release the material. Specifically, this includes a release sheet in which a release agent is applied to the surface of a release sheet substrate.

[0118] A resin film is preferred as the substrate for the release sheet, and 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 rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, and fluorine resins. The thickness of the release sheet is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 150 μm.

[0119] Method for manufacturing adhesive tape There are no particular limitations on the method for manufacturing the adhesive tape of the present invention, and it can be manufactured by known methods. For example, the method for manufacturing an adhesive tape having a base material, an adhesive layer provided on one side of the base material, and a buffer layer provided on the other side of the base material is as follows.

[0120] When the buffer layer is formed from a buffer layer-forming composition containing an energy ray polymerizable compound, the buffer layer is formed by coating and curing the buffer layer-forming composition onto a release sheet, and the buffer layer is bonded to the substrate. The release sheet is then removed to obtain a laminate of the buffer layer and the substrate. Alternatively, when the buffer layer is a layer containing a polyolefin resin film, the buffer layer and the substrate are bonded together to obtain a laminate of the buffer layer and the substrate.

[0121] Then, the adhesive layer provided on the release sheet is bonded to the substrate side of the laminate, and an adhesive tape can be manufactured in which the release sheet is attached to the surface of the adhesive layer. The release sheet attached to the surface of the adhesive layer can be peeled off and removed as appropriate before use of the adhesive tape.

[0122] One method for forming an adhesive layer on a release sheet is to directly apply an adhesive (adhesive composition) to the release sheet using a known application method, and then heat-dry the applied film to form the adhesive layer.

[0123] Alternatively, an adhesive layer may be formed by directly applying an adhesive (adhesive composition) to one side of the substrate. Examples of adhesive application methods include the spray coating method, bar coating method, knife coating method, roll coating method, blade coating method, die coating method, gravure coating method, etc., as described in the method for manufacturing the buffer layer.

[0124] One method for forming a buffer layer on a release sheet is to directly apply a buffer layer-forming composition to the release sheet using a known coating method to form a coating film, and then irradiate this coating film with energy rays to form the buffer layer. Alternatively, the buffer layer may be formed by directly applying the buffer layer-forming composition to one side of a substrate and then heating and drying it or irradiating the coating film with energy rays.

[0125] Examples of methods for applying the buffer layer-forming composition include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating. Furthermore, to improve applicability, an organic solvent may be added to the buffer layer-forming composition, and the solution may be applied onto a release sheet.

[0126] When the buffer layer forming composition contains an energy ray polymerizable compound, it is preferable to form a buffer layer by curing the coated film of the buffer layer forming composition by irradiating it with energy rays. The curing of the buffer layer may be performed in a single curing treatment or in multiple stages. For example, the coated film on the release sheet may be completely cured to form a buffer layer before being bonded to the substrate, or the buffer layer forming film may be formed in a semi-cured state without completely curing the coated film, and after bonding the buffer layer forming film to the substrate, it may be irradiated with energy rays again to completely cure it and form a buffer layer. Ultraviolet light is preferred as the energy ray used in the curing treatment. When curing, the coated film of the buffer layer forming composition may be exposed, but it is preferable to cure it by irradiating it with energy rays while the coated film is covered with a release sheet or substrate and the coated film is not exposed.

[0127] If the buffer layer is a layer containing a polyolefin resin film, the buffer layer and the substrate may be bonded together by extrusion lamination. Specifically, the polyolefin resin constituting the buffer layer is melted and kneaded using a T-die film-making machine or the like, and the molten polyolefin resin is extruded and laminated onto one side of the substrate while the substrate is moved at a constant speed. Alternatively, the buffer layer may be directly laminated onto the substrate by heat sealing or the like. Furthermore, it may be laminated via an easy-adhesion layer using methods such as dry lamination.

[0128] Furthermore, a method for manufacturing an adhesive tape having buffer layers on both sides of the base material can be obtained, for example, by the method described above, by obtaining a laminate in which the buffer layer, base material, and buffer layer are stacked in that order, and then forming an adhesive layer on one side of the buffer layer.

[0129] Method for manufacturing semiconductor devices The adhesive tape according to the present invention is preferably used when the tape is attached to the surface of a semiconductor wafer to perform backside grinding of the wafer. More preferably, the adhesive tape according to the present invention is preferably used in DBG, in which backside grinding and wafer fragmentation are performed simultaneously. Particularly preferably, the adhesive tape according to the present invention is preferably used in LDBG, in which a group of chips with a small kerf width is obtained when the semiconductor wafer is fragmented. The term "group of chips" refers to a plurality of semiconductor chips that are held on the adhesive tape according to the present invention and are aligned in the shape of a wafer. As a non-limited example of the use of adhesive tape, a method for manufacturing a semiconductor device will be described in more detail below.

[0130] The method for manufacturing a semiconductor device specifically comprises at least the following steps 1 to 4. Step 1: The above adhesive tape is attached to the surface of the semiconductor wafer, and the adhesive tape is cut along the outer edge of the semiconductor wafer. Step 2: A step of forming grooves from the surface side of a semiconductor wafer, or forming a modified region inside a semiconductor wafer from the surface or back surface of a semiconductor wafer. Step 3: A semiconductor wafer on which adhesive tape has been applied to the surface and on which the groove or modified region has been formed is ground from the back side to separate it into multiple chips, starting from the groove or modified region. Step 4: The process of peeling the adhesive tape off the individual semiconductor wafers (i.e., multiple semiconductor chips).

[0131] The following describes in detail each step of the manufacturing method for the semiconductor device described above. (Process 1) In step 1, the adhesive tape of the present invention is attached to the surface of a semiconductor wafer via an adhesive layer and cut along the outer circumference of the semiconductor wafer. The adhesive tape is attached so as to cover the semiconductor wafer and the outer circumference table that extends around its periphery. The adhesive tape is then cut along the outer circumference of the semiconductor wafer using a cutter or the like. The cutting speed is usually 10 to 300 mm / s. The temperature of the cutter blade during cutting may be room temperature, or the cutter blade may be heated before cutting.

[0132] This step may be performed before or after step 2, which will be described later. For example, when forming a modified region on a semiconductor wafer, it is preferable to perform step 1 before step 2. On the other hand, when forming grooves on the surface of a semiconductor wafer by dicing or the like, step 1 is performed after step 2. That is, adhesive tape is applied in step 1 to the surface of the wafer having grooves formed in step 2, which will be described later.

[0133] The semiconductor wafer used in this manufacturing method may be a silicon wafer, or a wafer made of gallium arsenide, silicon carbide, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is usually around 500 to 1000 μm. In addition, the semiconductor wafer usually has circuits formed on its surface. Circuit formation on the wafer surface can be carried out by various methods, including conventionally used methods such as etching and lift-off methods.

[0134] (Process 2) In step 2, grooves are formed from the surface side of the semiconductor wafer, or modified regions are formed inside the semiconductor wafer from the surface or back surface. The grooves formed in this process are shallower than the thickness of the semiconductor wafer. The grooves can be formed by dicing using conventionally known wafer dicing equipment. Furthermore, in step 3, described later, the semiconductor wafer is divided into multiple semiconductor chips along the grooves.

[0135] Furthermore, the modified region is a brittle part of the semiconductor wafer, and it is the starting point for the semiconductor wafer to break down into individual semiconductor chips due to the thinning of the semiconductor wafer by grinding during the grinding process or the force applied by grinding. In other words, in step 2, the groove and the modified region are formed along the dividing line when the semiconductor wafer is divided into individual semiconductor chips in step 3, which will be described later.

[0136] The modified region is formed by irradiating the semiconductor wafer with a laser focused on the interior of the wafer. The laser irradiation may be performed from either the front or back side of the semiconductor wafer. In the embodiment where the modified region is formed, if step 2 is performed after step 1 and the laser irradiation is performed from the wafer surface, the laser will be irradiated onto the semiconductor wafer via adhesive tape. A semiconductor wafer, to which adhesive tape has been applied and to which grooves or modified regions have been formed, is placed on a chuck table and held by suction to the chuck table. In this case, the semiconductor wafer is positioned with its surface side facing the table when it is suctioned.

[0137] (Step 3) After steps 1 and 2, the back surface of the semiconductor wafer on the chuck table is ground to separate the semiconductor wafer into multiple semiconductor chips. In this process, back grinding is performed to thin the semiconductor wafer at least up to the bottom of the groove, if grooves are to be formed on the semiconductor wafer. This back grinding creates cuts that penetrate the wafer, and the semiconductor wafer is divided by these cuts into individual semiconductor chips.

[0138] On the other hand, if a modified region is formed, the grinding surface (back surface of the wafer) may reach the modified region through grinding, but it does not need to reach the modified region precisely. In other words, grinding should be done up to a position close to the modified region so that the semiconductor wafer is broken down into individual semiconductor chips, starting from the modified region. For example, the actual fragmentation of semiconductor chips may be performed by attaching a pickup tape, as described later, and then stretching the pickup tape.

[0139] Additionally, after the backside grinding is complete and prior to picking up the chip, dry polishing may be performed.

[0140] The shape of the individual semiconductor chips may be rectangular or elongated, such as a rectangle. The thickness of the individual semiconductor chips is not particularly limited, but is preferably around 5 to 100 μm, and more preferably 10 to 45 μm. With LDBG, which involves creating a modified region inside the wafer with a laser and fragmenting the wafer using stress during back-side grinding, it becomes easy to achieve a thickness of 50 μm or less, more preferably 10 to 45 μm. The size of the individual semiconductor chips is not particularly limited, but a chip size of 600 mm is preferred. 2 Less than, more preferably 400 mm 2 Less than 300 mm, more preferably 300 mm 2 It is less than.

[0141] By using the adhesive tape of the present invention, even with thin and / or small semiconductor chips, cracks in the semiconductor chip are prevented during the subsequent removal of the adhesive tape (step 4).

[0142] (Step 4) The adhesive tape is peeled off the individual semiconductor wafer (i.e., multiple semiconductor chips aligned in the wafer shape). This process is carried out, for example, by the following method. First, if the adhesive layer of the adhesive tape is formed from an energy-ray curable adhesive, the adhesive layer is cured by irradiating it with energy rays. Next, the pickup tape is attached to the back side of the individual semiconductor wafers, and its position and orientation are aligned so that it can be picked up. At this time, the ring frame placed on the outer circumference of the wafer is also attached to the pickup tape, and the outer edge of the pickup tape is fixed to the ring frame. The wafer and ring frame may be attached to the pickup tape at the same time, or at different times. Next, the adhesive tape is peeled off from the multiple semiconductor chips held on the pickup tape.

[0143] Subsequently, multiple semiconductor chips are picked up from the pickup tape and fixed onto a substrate or other surface to manufacture a semiconductor device. The pickup tape is not particularly limited, but for example, it is composed of an adhesive tape comprising a base material and an adhesive layer provided on at least one surface of the base material.

[0144] Alternatively, adhesive tape can be used instead of pickup tape. Examples of adhesive tape include a laminate of a film-like adhesive and a release sheet, a laminate of a dicing tape and a film-like adhesive, and a dicing-die bonding tape consisting of an adhesive layer and a release sheet that have the functions of both a dicing tape and a die bonding tape. In other words, this embodiment may include a step of attaching the dicing-die bonding tape to the back surface of the semiconductor wafer. Alternatively, a film-like adhesive may be attached to the back surface of the individualized semiconductor wafer before attaching the pickup tape. When using a film-like adhesive, the film-like adhesive may have the same shape as the wafer.

[0145] Here, if the adhesive layer of the adhesive tape is formed from an energy-ray curable adhesive, when irradiated with energy rays, the portion of the adhesive layer in close contact with the wafer hardens, and the adhesive strength in that portion is sufficiently reduced. However, in the portion of the adhesive layer that is not in close contact with the wafer and is exposed to the atmosphere, the hardening of the adhesive is usually inhibited by oxygen in the atmosphere, and it does not harden even when irradiated with energy rays such as ultraviolet rays, and the adhesive strength is not sufficiently reduced. For this reason, as shown in Figure 3, when the thickness of a semiconductor wafer is made extremely thin to about 30 μm by back grinding, when dicing / die bonding tape is attached to the back surface of the semiconductor wafer, the unhardened portion of the adhesive layer of the adhesive tape attached to the surface of the semiconductor wafer comes into contact with the adhesive layer of the dicing / die bonding tape and adheres to it. When an attempt is made to peel off the adhesive tape that has adhered to the dicing / die bonding tape, the adhesive tape and the dicing / die bonding tape become one, and the dicing / die bonding tape also bends along with the bending of the adhesive tape. The wafer or chip sandwiched between the adhesive tape and the dicing / die bonding tape also bends at the same time. As a result, the chip becomes more prone to cracking. In addition, adhesive layers such as dicing and die bonding tapes may break due to bending, and fragments may fall off.

[0146] On the other hand, the adhesive tape according to this embodiment can prevent cracks from occurring in the semiconductor chip when the adhesive tape is peeled off. Figure 5 is a schematic diagram of a laminate in which a dicing / die bonding tape 30 is further attached to a semiconductor wafer 20 that has been back-ground with the adhesive tape according to this embodiment attached. Figure 5 shows the case in which the dicing / die bonding tape 30 is attached to a semiconductor wafer 20 that has been back-ground to an extremely thin thickness of about 30 μm. In the adhesive tape according to this embodiment, the adhesive strength of the adhesive layer can be sufficiently reduced by irradiation with energy rays even when exposed to an atmospheric environment. Therefore, as shown in Figure 5, when the thickness of the semiconductor wafer is made extremely thin to about 30 μm by back-ground, even if a part of the adhesive layer of the adhesive tape attached to the surface of the semiconductor wafer comes into contact with an adhesive layer such as the dicing / die bonding tape, the two will not stick together. Therefore, the adhesive tape can be peeled off without becoming integrated with the dicing / die bonding tape. As a result, cracks in the chip can be suppressed.

[0147] When using adhesive tape or when a film-like adhesive is applied to the back side of a semiconductor wafer that has been separated before applying the pickup tape, multiple semiconductor chips on the adhesive tape or pickup tape are picked up together with the adhesive layer, which is divided to match the shape of the semiconductor chips. The semiconductor chips are then fixed onto a substrate or the like via the adhesive layer, and a semiconductor device is manufactured. The division of the adhesive layer is performed by laser or expansion.

[0148] The above describes an example of using the adhesive tape according to the present invention in a method of framing semiconductor wafers by DBG or LDBG. The adhesive tape according to the present invention is preferably used in LDBG, which yields a smaller kerf width and thinner chip group when semiconductor wafers are framing. The adhesive tape according to the present invention can also be used in normal back grinding, and can also be used to temporarily hold workpieces during processing of glass, ceramics, etc. It can also be used as various types of re-peelable adhesive tapes. [Examples]

[0149] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0150] The measurement and evaluation methods are as follows. The results are shown in Table 1.

[0151] [Surface modulus] For adhesive tapes used in semiconductor processing, with one side of the adhesive layer exposed to the atmosphere, an ultraviolet irradiation device (Lintec Corporation, device name "RAD 2000") was used to irradiate the tape at an illuminance of 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 Under these conditions, ultraviolet light was irradiated onto the adhesive tape from the substrate side. Using a silicon nitride cantilever (Bruker Corporation, "SCANASYST-AIR", nominal tip radius: 2 nm, resonant frequency: 70 kHz, spring constant: 0.4 N / m) mounted on an atomic force microscope (Bruker Corporation, "Dimension Icon"), the surface of the adhesive layer was pressed and pulled at room temperature with a pressing depth of 5 nm and a scan speed of 5 Hz. The obtained force curve (horizontal axis is sample deformation, vertical axis is measured load) was fitted to the JKR theoretical formula to calculate the surface modulus. The average value obtained from measurements taken at 4096 points within a 5 μm × 5 μm area of ​​the adhesive layer surface was defined as the surface modulus (MPa).

[0152] [Exfoliation evaluation] Adhesive tape was attached to a 12-inch diameter, 775 μm thick silicon wafer using a backgrinding tape laminator (Lintec Corporation, model name "RAD-3510F / 12") and cut along the outer edge of the silicon wafer. A laser saw (Disco Corporation, model name "DFL7361") was used to irradiate the silicon wafer with a 1342 nm wavelength laser beam from the surface, forming a modified region inside the silicon wafer with a chip size of 5 mm x 5 mm. Next, a grinder (Disco Corporation, model name "DGP8760") was used to grind the back surface of the silicon wafer to a thickness of 30 μm after grinding. At this time, the adhesive tape was sized to cover the outer edge of the silicon wafer after grinding, and was 1.0 mm larger than the outer edge of the silicon wafer. An ultraviolet irradiation device (Lintec Corporation, model name "RAD 2000") was used at an irradiance of 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 Under these conditions, ultraviolet light was irradiated onto the adhesive tape from the substrate side, i.e., the surface side of the silicon wafer. The adhesive layer surface of the dicing / die bonding tape (Lintec Corporation, LD01D-07) was attached to the back surface of the silicon wafer while heating it to 60°C using a tape mounter (Lintec Corporation, device name "ADWILL RAD-2700"). The adhesive tape was peeled off. At this time, the degree of peeling of the adhesive layer of the dicing / die bonding tape was observed and evaluated according to the following criteria. A: The peeled area is less than 70%. B: The area that has been peeled off is between 70% and 97%. C: More than 97% of the surface area has been peeled off.

[0153] [Surface free energy] For adhesive tapes used in semiconductor processing, with one side of the adhesive layer exposed to the atmosphere, an ultraviolet irradiation device (Lintec Corporation, device name "RAD 2000") was used to irradiate the tape at an illuminance of 220 mW / cm². 2 and light intensity of 500 mJ / cm 2Under these conditions, ultraviolet light was irradiated onto the adhesive tape from the substrate side. Using a contact angle meter (manufactured by Kyowa Interface Chemical Co., Ltd., device name "DM-70"), diiodomethane, 1-bromonaphthalene, and distilled water were used as droplets, and the contact angle (measurement temperature: 25°C) was measured by the static droplet method in accordance with JIS R 3257:1999. Based on the value of the contact angle, the surface free energy (mJ / m) was calculated using the Kitazaki-Hata method. 2 ) was calculated.

[0154] [Peel strength] For a semiconductor processing adhesive tape (25 mm wide) consisting of a base material and an adhesive layer, one side of the adhesive layer was exposed to the atmosphere, and an ultraviolet irradiation device (Lintec Corporation, device name "RAD 2000") was used to irradiate it at an illuminance of 220 mW / cm². 2 and light intensity of 500 mJ / cm 2 Under these conditions, ultraviolet light was irradiated onto the adhesive tape from the substrate side. A PMMA board (2 mm thick, 70 mm wide, 150 mm long, manufactured by Mitsubishi Chemical Corporation, "Acrylite L001") was attached to the exposed surface of the adhesive layer at 23°C and 50% RH using a 2 kg roll in one pass-through motion. After leaving it for 30 minutes, the peel strength of the adhesive tape was measured when peeled 180° at a measurement temperature of 25°C and a peeling speed of 300 mm / min. Two measurements were taken under the same conditions, and the average values ​​are shown in Table 1.

[0155] [Adhesion energy] For adhesive tapes used in semiconductor processing, with one side of the adhesive layer exposed to the atmosphere, an ultraviolet irradiation device (Lintec Corporation, device name "RAD 2000") was used to irradiate the tape at an illuminance of 220 mW / cm². 2 and light intensity of 500 mJ / cm 2Under these conditions, ultraviolet light was irradiated onto the adhesive tape from the substrate side. Using a silicon nitride cantilever (Bruker Corporation, "SCANASYST-AIR", nominal tip radius: 2 nm, resonant frequency: 70 kHz, spring constant: 0.4 N / m) mounted on an atomic force microscope (Bruker Corporation, "Dimension Icon"), the surface of the adhesive layer was pressed and pulled at room temperature with a pressing depth of 5 nm and a scan speed of 5 Hz. The obtained force curve (horizontal axis is sample deformation, vertical axis is measured load) was fitted to the JKR theoretical formula to calculate the surface modulus. The average value obtained from measurements taken at 4096 points within a 5 μm × 5 μm area of ​​the adhesive layer surface was used as the adhesion energy (J / m²). 2 )

[0156] All mass values ​​in the following examples and comparative examples are calculated on a solid content basis.

[0157] <Example 1> (1) Base material As the substrate, a PET film with an easy-adhesion layer on both sides (Cosmoshine A4300, manufactured by Toyobo Co., Ltd., thickness: 50 μm, Young's modulus at 23°C: 2550 MPa) was prepared.

[0158] (2) Adhesive layer (Preparation of adhesive composition) An acrylic polymer was obtained by copolymerizing 50 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA). This polymer was then reacted with 2-methacryloyloxyethyl isocyanate (MOI) to add to 90 mol% of the total hydroxyl groups of the acrylic polymer, thereby obtaining an energy-ray curable acrylic resin.

[0159] To 100 parts by mass of this energy-ray curable acrylic resin, 12 parts by mass of polyfunctional urethane acrylate, an energy-ray curable compound, 1.1 parts by mass of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (manufactured by IGM Resins BV, product name "OMNIRAD TPO") as a photopolymerization initiator were added, and the mixture was diluted with methyl ethyl ketone to prepare a coating solution of an adhesive composition with a solid content of 32% by mass.

[0160] (3) Preparation of adhesive tape A coating solution of the adhesive composition obtained above was applied to the release surface of a release sheet (Lintec Corporation, product name "SP-PET381031"), and the sheet was heated and dried to form an adhesive layer with a thickness of 30 μm on the release sheet. The surface of the formed adhesive layer was bonded to a substrate to produce an adhesive tape for semiconductor processing.

[0161] <Example 2> An adhesive tape for semiconductor processing was prepared in the same manner as in Example 1, except that in the preparation of the adhesive composition, 50 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 15 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer.

[0162] <Example 3> In preparing the adhesive composition, 60 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0163] <Example 4> In preparing the adhesive composition, 60 parts by mass of n-butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0164] <Example 5> In preparing the adhesive composition, 65 parts by mass of n-butyl acrylate (BA), 5 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0165] <Example 6> In preparing the adhesive composition, 60 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0166] <Example 7> In preparing the adhesive composition, 40 parts by mass of 2-ethylhexyl acrylate (2EHA), 20 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), and 30 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0167] <Example 8> In preparing the adhesive composition, 60 parts by mass of ethyl acrylate (EA), 10 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 15 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0168] <Example 9> In preparing the adhesive composition, 60 parts by mass of n-butyl acrylate (BA), 10 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 15 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer. An adhesive tape for semiconductor processing was then prepared in the same manner as in Example 1, except that 2.4 parts by mass of 2,2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins BV, product name "OMNIRAD 651") was used as a photopolymerization initiator instead of 3.3 parts by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0169] <Example 10> An adhesive tape for semiconductor processing was prepared in the same manner as in Example 1, except that in the preparation of the adhesive composition, 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), 21 parts by mass of 2-hydroxyethyl acrylate (HEA), and 7 parts by mass of 2-hydroxyethyl methacrylate (HEMA) were copolymerized to obtain an acrylic polymer.

[0170] <Comparative Example 1> An adhesive tape for semiconductor processing was prepared in the same manner as in Example 1, except that in the preparation of the adhesive composition, 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized to obtain an acrylic polymer.

[0171] [Table 1]

[0172] From the above results, it can be seen that, with the semiconductor processing adhesive tape according to the present invention, the surface modulus of the adhesive layer decreases and the adhesive strength decreases sufficiently even in the atmosphere when irradiated with energy rays such as ultraviolet rays. Therefore, by using the adhesive tape according to the present invention, even when the thickness of the semiconductor wafer is made extremely thin by back grinding, the occurrence of cracks in the semiconductor chip can be suppressed and the productivity of semiconductor devices can be improved. [Explanation of Symbols]

[0173] 10 Adhesive Tapes 20 Semiconductor wafers 30 Adhesive Tapes (Dicing / Die Bonding Tapes) 100 pieces of adhesive tape according to the embodiment 110 Base material 120 Adhesive layer

Claims

1. An adhesive tape having a base material and an adhesive layer, With one surface of the adhesive layer exposed to the atmosphere, the illuminance was 220 mW / cm². ２ and light intensity of 500 mJ / cm ２ An adhesive tape for semiconductor processing, wherein the surface modulus of the exposed surface of the adhesive layer after irradiation of the adhesive tape with ultraviolet light under the specified conditions is 5 MPa or more.

2. The adhesive layer contains an acrylic resin, The semiconductor processing adhesive tape according to claim 1, wherein the content of polymerization units derived from HEMA is 6 parts by mass or more per 100 parts by mass of the total amount of the acrylic resin.

3. With one surface of the adhesive layer exposed to the atmosphere, the illuminance was 220 mW / cm². ２ and light intensity of 500 mJ / cm ２ After irradiating the adhesive tape with ultraviolet light under the specified conditions, the surface free energy of the exposed surface of the adhesive layer was 36 mJ / m². ２ A semiconductor processing adhesive tape according to claim 1 or 2, wherein the amount is less than [amount missing].

4. A step of attaching a semiconductor processing adhesive tape according to any one of claims 1 to 3 to the surface of a semiconductor wafer, and cutting the adhesive tape along the outer circumference of the semiconductor wafer, A step of forming a groove from the surface side of the semiconductor wafer, or forming a modified region inside the semiconductor wafer from the surface or back surface of the semiconductor wafer, A step of grinding a semiconductor wafer on which the adhesive tape is attached to the surface and on which the groove or modified region is formed, from the back side to separate it into multiple chips starting from the groove or modified region, The process of peeling the adhesive tape from the plurality of chips, A method for manufacturing a semiconductor device comprising the same equipment.

5. Furthermore, the method for manufacturing a semiconductor device according to claim 4, further comprising the step of attaching a dicing die bonding tape to the back surface of a semiconductor wafer.

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