CN116941017A

CN116941017A - Adhesive tape for semiconductor processing and method for manufacturing semiconductor device

Info

Publication number: CN116941017A
Application number: CN202280017571.9A
Authority: CN
Inventors: 饭塚亮; 前田淳; 田村和幸
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2021-03-22
Filing date: 2022-01-19
Publication date: 2023-10-24
Also published as: KR20230160228A; WO2022201788A1; JPWO2022201788A1; TW202237771A

Abstract

The invention provides an adhesive tape for semiconductor processing, which can inhibit cracks of chips when the adhesive tape is peeled. The adhesive tape for semiconductor processing comprises a substrate and an adhesive layer, wherein the illuminance of one surface of the adhesive tape is 220mW/cm when the adhesive tape is exposed to the atmosphere ² The light quantity was 500mJ/cm ² The adhesive tape was irradiated with ultraviolet rays, and a PMMA plate was attached to the exposed surface of the adhesive layer at 23℃and 50% RH with a 2kg roller to and fro, and left for 30 minutes, and then the adhesive tape was peeled at 180℃to have a peel strength of 1600mN/25mm or less.

Description

Adhesive tape for semiconductor processing and method for manufacturing semiconductor device

Technical Field

The present invention relates to an adhesive tape for semiconductor processing, and more particularly, to an adhesive tape suitable for temporarily holding a semiconductor wafer or a chip when manufacturing a semiconductor device by a method of forming a groove on the surface of a wafer or forming a modified region inside the wafer by laser and singulating the wafer by stress or the like at the time of back grinding the wafer, and a method of manufacturing a semiconductor device using the adhesive tape.

Background

With the progress of miniaturization and multifunction of various electronic devices, miniaturization and thinning of semiconductor chips mounted therein are also demanded. For thinning the chip, the back surface of the semiconductor wafer is generally polished to adjust the thickness. In order to obtain a thinned chip, a technique called a pre-dicing method (DBG: dicing Before Grinding; dicing before polishing) is sometimes used, in which grooves of a predetermined depth are formed from the front surface side of a wafer by using a dicing blade, and then polishing is performed from the back surface side of the wafer, and the wafer is singulated by polishing to obtain chips. Since the back surface grinding of the wafer and the singulation of the wafer can be simultaneously performed by the DBG, thin chips can be efficiently manufactured.

In recent years, as a modification of the pre-dicing method, there has been proposed a method of forming a modified region inside a wafer by a laser beam and singulating the wafer by using stress or the like at the time of polishing the back surface of the wafer. Hereinafter, this method may be referred to as LDBG (Laser Dicing Before Grinding; laser cutting before polishing). In LDBG, since the wafer is cut along the crystal direction starting from the modified region, occurrence of chipping (chipping) can be reduced compared to the precutting method using a dicing blade. As a result, a chip excellent in flexural strength can be obtained, and further thinning of the chip can be facilitated. In addition, the yield of chips is excellent because there is no area where the wafer is shaved off by the dicing blade, that is, because the kerf width (kerf width) is extremely small, compared to the DBG in which the trench of a certain depth is formed on the wafer surface by the dicing blade.

Conventionally, when back grinding a semiconductor wafer or manufacturing chips by DBG or LDBG, an adhesive tape called a back grinding sheet (back grinding sheet) is usually attached to the wafer surface in order to protect circuits on the wafer surface and to hold the semiconductor wafer and the semiconductor chips. After back grinding, an adhesive tape having an adhesive layer is attached to the ground surface. Then, the adhesive tape attached to the wafer surface is irradiated with energy rays such as ultraviolet rays to reduce the adhesive force, and then peeled off. Through this step, an adhesive tape is attached to the back surface of the wafer.

In contrast, patent document 1 proposes an adhesive tape having an adhesive layer using an adhesive having a reduction rate of the adhesive strength of 60% or more after irradiation of ultraviolet rays in the presence of oxygen. However, when the adhesive tape described in patent document 1 is used, chipping and breakage of the chip (hereinafter, sometimes referred to as "chip cracking") may occur when the adhesive tape is peeled off when the finished thickness of the chip is thinned to about 30 μm.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2015-185691

Disclosure of Invention

Technical problem to be solved by the invention

As a result of intensive studies to solve the above-described problems, the inventors of the present application have found that, due to the reduction in thickness of a semiconductor wafer after polishing, an area in which the adhesive strength is not sufficiently reduced even when an adhesive tape is irradiated with energy rays such as ultraviolet rays is generated, and that cracks are generated in a chip when the adhesive tape is peeled.

Fig. 1 is a schematic view showing a case where the thickness of a semiconductor wafer 20 is gradually thinned when the semiconductor wafer 20 to which an adhesive tape 10 is attached is back-polished. In fig. 1, (1) shows the case before back surface grinding, (3) shows the case when the thickness of the semiconductor wafer is about 30 μm, and (2) shows the case in the process from (1) to (3). Generally, as shown in fig. 1 (1), the side surface of the semiconductor wafer 20 before polishing is circular. The adhesive tape 10 protects the circuitry on the wafer surface and typically comprises a flat and hard raw material that can hold the wafer and chips to a degree. Therefore, when the adhesive tape 10 is attached to the wafer 20 before polishing, as shown in fig. 1 (1), an area where the adhesive tape is not adhered slightly occurs at the outer edge of the wafer 20.

As shown in fig. 1, as the back grinding of the wafer proceeds with (1), (2) and (3), the thickness of the semiconductor wafer 20 becomes thinner and the size also changes, but the size of the adhesive tape 10 does not change. When the wafer is back-polished to an extremely small thickness of about 30 μm, a circular portion of the side surface of the wafer 20 is removed as shown in fig. 1 (3). Therefore, even when the shape of the adhesive tape is substantially the same as that of the wafer before polishing as in fig. 1 (1), the outer edge portion of the adhesive tape 10 is exposed on the outer periphery of the wafer 20 as in fig. 1 (3) after polishing. When the adhesive tape is irradiated with energy rays such as ultraviolet rays in this state, the adhesive force is sufficiently reduced at the portion of the adhesive tape that is in close contact with the wafer. However, in a portion of the adhesive tape that is not in close contact with the wafer but is exposed to the atmosphere (exposed portion of the outer edge portion), curing of the adhesive is hindered by oxygen in the atmosphere, and the adhesive force is not sufficiently reduced even by irradiation of energy rays such as ultraviolet rays. That is, the adhesive tape has an uncured portion after irradiation with energy rays such as ultraviolet rays.

For example, dicing die bonding tape as an adhesive tape is attached to the back surface of the wafer after back grinding. Fig. 2 and 3 are schematic views of a laminate in which dicing die attach tape 30 is further attached to back-ground semiconductor wafer 20 to which adhesive tape 10 is attached. Dicing die attach tape 30 includes an adhesive layer (not shown) and is attached to semiconductor wafer 20 by the adhesive layer. Fig. 3 shows a state in which dicing die attach tape 30 is attached to semiconductor wafer 20 after back grinding, which is extremely thin to a thickness of about 30 μm. On the other hand, fig. 2 shows a case where the dicing die bonding tape 30 is attached to the semiconductor wafer 20 and the thickness of the semiconductor wafer 20 is larger than that of fig. 3. As shown in fig. 2, when the thickness of the back-ground semiconductor wafer 20 is greater, the uncured portion of the adhesive tape 10 does not come into contact with the adhesive layer of the dicing die-bonding tape 30 even if the dicing die-bonding tape 30 is attached. However, as shown in fig. 3, when the thickness of the semiconductor wafer 20 after back grinding is extremely thinned to about 30 μm, if the dicing die-bonding tape 30 is attached, there is a possibility that the uncured portion of the adhesive tape 10 contacts and adheres to the adhesive layer of the dicing die-bonding tape 30. The dicing tape is not cut like a wafer. Therefore, when the adhesive tape attached to the dicing die bonding tape is to be peeled off, the adhesive tape and the dicing die bonding tape are integrated, and the dicing die bonding tape is also bent along with the bending of the adhesive tape. The wafer and the chip sandwiched between the adhesive tape and the dicing die attach tape are also bent at the same time. As a result, cracks are likely to occur in the chip. In addition, the adhesive layer of the dicing die-bonding tape may be broken by bending, and fragments thereof may be peeled off.

That is, since the adhesive tape has a region in which the adhesive force is not sufficiently reduced even when energy rays such as ultraviolet rays are irradiated, when the thickness of the semiconductor wafer is extremely reduced by back grinding, there is a problem in that cracks of the chip are easily generated when the adhesive tape is peeled.

The present invention has been made in view of the above-described conventional techniques, and an object thereof is to provide an adhesive tape for semiconductor processing that can suppress cracking of a chip when the adhesive tape is peeled off.

Technical means for solving the technical problems

The gist of the present invention for solving such a technical problem is as follows.

(1) An adhesive tape for semiconductor processing, which is an adhesive tape having a base material and an adhesive layer, wherein,

exposing one side of the adhesive layer to an atmosphere at an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The conditions of (2) irradiating the adhesive tape with ultraviolet rays at 23 ℃ and 50% RHAfter a PMMA plate was attached to the exposed surface of the adhesive layer with a 2kg roller and left to stand for 30 minutes, the adhesive tape was peeled 180℃therefrom to have a peel strength of 1600mN/25mm or less.

(2) The adhesive tape for semiconductor processing according to (1), wherein the adhesive layer comprises an acrylic resin,

The content of polymerized units derived from HEMA is 6 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin.

(3) The adhesive tape for semiconductor processing according to (1) or (2), wherein the illuminance is 220mW/cm in a state in which one surface of the adhesive layer is exposed to an atmosphere ² The light quantity was 500mJ/cm ² The exposed surface of the adhesive layer having a surface free energy of less than 36mJ/m after irradiation of ultraviolet rays to the adhesive tape ² 。

(4) A method for manufacturing a semiconductor device includes the steps of:

attaching the adhesive tape for semiconductor processing described in any one of (1) to (3) to a surface of a semiconductor wafer, and cutting the adhesive tape along an outer periphery of the semiconductor wafer;

forming a trench from a front surface side of the semiconductor wafer or forming a modified region in the semiconductor wafer from a front surface or a back surface of the semiconductor wafer;

polishing a semiconductor wafer having the adhesive tape attached to a surface thereof and having the grooves or the modified regions formed thereon from a back surface side, and singulating the semiconductor wafer into a plurality of chips with the grooves or the modified regions as a starting point; a kind of electronic device with high-pressure air-conditioning system

And peeling the adhesive tape from the plurality of chips.

(5) The method for manufacturing a semiconductor device according to (4), further comprising a step of attaching dicing tape to the back surface of the semiconductor wafer.

Effects of the invention

The adhesive tape for semiconductor processing of the present invention can sufficiently reduce the adhesive force of the adhesive layer in an atmosphere. As a result, the occurrence of cracks in the semiconductor chip can be suppressed.

Drawings

Fig. 1 is a schematic diagram showing a process of back-grinding a semiconductor wafer.

Fig. 2 is a schematic view of a laminate composed of the adhesive tape 10, the back-polished semiconductor wafer 20, and the dicing die bond tape 30, showing a case where the thickness of the semiconductor wafer 20 is larger than that of fig. 3.

Fig. 3 is a schematic view of a laminate including the adhesive tape 10, the back-polished semiconductor wafer 20, and the dicing die bond tape 30, and shows a state in which the back-polished semiconductor wafer 20 is extremely thinned to a thickness of about 30 μm.

Fig. 4 is a schematic view showing the adhesive tape of the present embodiment.

Fig. 5 is a schematic view of a laminate including the adhesive tape, the back-polished semiconductor wafer 20, and the dicing die-bonding tape 30 according to the present embodiment, and shows a case where the back-polished semiconductor wafer 20 is back-polished to an extremely thin thickness of about 30 μm.

Detailed Description

Hereinafter, the adhesive tape for semiconductor processing of the present invention will be specifically described. First, main terms used in the present specification will be explained.

In the present specification, for example, "(meth) acrylate" is used as a term indicating both "acrylate" and "methacrylate", and other similar terms are also the same.

"semiconductor processing" means that the semiconductor wafer can be used for conveyance, back grinding, and dicing of the semiconductor wafer; in each step of picking up semiconductor chips.

The "front surface" of a semiconductor wafer refers to the surface on which a circuit is formed, and the "back surface" refers to the surface on which no circuit is formed.

Singulation of semiconductor wafers refers to the separation of semiconductor wafers into individual semiconductor chips by circuit.

The DBG is a method of forming a trench having a certain depth on the front surface side of a wafer, polishing the wafer from the back surface side, and singulating the wafer by polishing. The grooves formed on the wafer surface side are formed by a method such as blade dicing, laser dicing, or plasma dicing. In addition, LDBG is a modification of DBG, and is a method of forming a modified region inside a wafer by laser, and singulating the wafer by stress or the like at the time of polishing the back surface of the wafer.

Next, the structure of each member of the adhesive tape for semiconductor processing of the present invention will be described in further detail. In addition, the adhesive tape for semiconductor processing of the present invention is abbreviated as "adhesive tape".

In the present embodiment, as shown in fig. 4, the adhesive tape 100 refers to a laminate including a base material 110 and an adhesive layer 120. The adhesive tape 100 may also have a buffer layer on at least one side of the substrate 110. Further, other constituent layers than the above may be included. For example, a primer layer may be formed on the surface of the base material on the adhesive layer side, or a release sheet for protecting the adhesive layer until use may be laminated on the surface of the adhesive layer. The substrate may be a single layer or a plurality of layers. The same applies to the adhesive layer and the buffer layer.

The following describes in further detail the structure of each member of the adhesive tape for semiconductor processing according to the present embodiment.

Is an adhesive layer

The adhesive tape of the present embodiment was irradiated with light of 220mW/cm in a state where one side of the adhesive layer was exposed to the atmosphere ² The light quantity was 500mJ/cm ² The conditions of (2) are such that the adhesive tape is irradiated with ultraviolet rays, and after the PMMA plate is attached to the exposed surface of the adhesive layer at 23 ℃ and 50% RH in a round trip with a 2kg roller and left for 30 minutes, the adhesive tape has a peel strength of 1600mN/25mm or less, preferably 1100mN/25mm or less, more preferably 980mN/25mm or less, and even more preferably 800mN/25mm or less when peeled at 180 ℃. When the peel strength is in the above range, the adhesive force of the adhesive layer can be sufficiently reduced, and as a result, the occurrence of cracks in the chip can be suppressed. The lower limit of the peel strength is not particularly limited, but is usually 50N/25mm, preferably 80N/25mm.

In the measurement of the peel strength, ultraviolet irradiation was performed from the substrate side. Furthermore, PMMA was polymethyl methacrylate, and as the PMMA plate, "ACRYLITE L001" manufactured by Mitsubishi Chemical Corporation having a thickness of 2mm, a width of 70mm, and a length of 150mm was used. The peel strength was measured under the conditions that the adhesive tape had a width of 25mm, a peeling speed of 300 mm/min and a measurement temperature of 25℃and the average value obtained by repeating the measurement under the same conditions was used as the peel strength.

The peel strength can be controlled in the following manner: the adhesive layer was prepared to contain an acrylic resin, and the amount of polymerized units derived from 2-hydroxyethyl methacrylate (hereinafter, sometimes abbreviated as HEMA) was further adjusted. In particular, the peel strength can be controlled within the above range by preparing the adhesive layer so that the content of the polymerized units derived from HEMA is 6 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin.

The adhesive tape of the present embodiment was irradiated with light of 220mW/cm in a state where one side of the adhesive layer was exposed to the atmosphere ² The light quantity was 500mJ/cm ² The surface free energy of the exposed surface of the adhesive layer after irradiation of ultraviolet rays to the adhesive tape is preferably less than 36mJ/m ² More preferably 32mJ/m ² Hereinafter, it is preferably 30mJ/m ² The following is given. The surface free energy is preferably within the above range, from the viewpoint of sufficiently reducing the adhesive force of the adhesive layer. The lower limit of the free energy of the surface is not particularly limited, and is usually 18mJ/m ² Preferably 22mJ/m ² 。

In the measurement of the surface free energy, ultraviolet irradiation is performed from the substrate side. The surface free energy was measured for the contact angle (measurement temperature: 25 ℃ C.) of each droplet, and was obtained by the Kitazaki-Hata method based on the value of the contact angle. Specifically, using diiodomethane, 1-bromonaphthalene and distilled water as liquid droplets, the contact angle (measurement temperature: 25 ℃ C.) was measured by the horizontal drop method based on JIS R3257:1999, and the surface free energy (mJ/m) was determined by the Kitazaki-Hata method based on the value of the contact angle ² )。

The surface free energy can be controlled in the following manner: the adhesive layer was prepared to contain an acrylic resin, further adjusting the amount of polymerized units from HEMA. In particular, the surface free energy can be controlled within the above range by preparing the adhesive layer so that the content of the polymerized units derived from HEMA is 6 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin.

In the adhesive tape of the present embodiment, the illuminance was 220mW/cm in a state where one surface of the adhesive layer was exposed to the atmosphere ² The light quantity was 500mJ/cm ² The surface elastic modulus of the exposed surface of the adhesive layer after irradiation of the adhesive tape with ultraviolet rays is preferably 5MPa or more, more preferably 6MPa or more, and still more preferably 6.5MPa or more. The surface elastic modulus is preferably set to the above range in view of sufficiently reducing the adhesive force of the adhesive layer. The upper limit of the surface elastic modulus is not particularly limited, but is usually 17MPa, preferably 14MPa.

In the measurement of the surface elastic modulus, ultraviolet irradiation is performed from the substrate side. Further, the surface elastic modulus was measured using an atomic force microscope. Specifically, a cantilever (cantilever) (tip radius: 2nm, resonance frequency: 70kHz, spring constant: 0.4N/m) of a silicon nitride material provided in an atomic force microscope was used to press in and separate the surface of the adhesive layer at room temperature at a press-in amount of 5nm and a scanning speed of 5 Hz. The surface elastic modulus was calculated by fitting (fitting) to the JKR theoretical equation with respect to the obtained force curve (horizontal axis represents the deformation of the sample and vertical axis represents the measurement load). The average value of the values obtained by measuring 4096 points in 5 μm×5 μm on the surface of the adhesive layer was used as the surface elastic modulus (MPa).

The surface elastic modulus can be controlled in the following manner: the adhesive layer was prepared to contain an acrylic resin, further adjusting the amount of polymerized units from HEMA. In particular, the surface elastic modulus can be controlled within the above range by preparing the adhesive layer such that the content of the polymerized units derived from HEMA is 6 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin.

Further, with the adhesive tape of the present embodiment, the illuminance was 220mW/cm in a state where one side of the adhesive layer was exposed to the atmosphere ² The light quantity was 500mJ/cm ² The adhesive energy (adhesion energy) of the exposed surface of the adhesive layer after irradiation of the adhesive tape with ultraviolet rays is preferably 0.220J/m ² Hereinafter, more preferably 0.200J/m ² Hereinafter, it is more preferably 0.190J/m ² The following is given. The above-mentioned adhesion energy is preferably set to the above-mentioned range in view of sufficiently reducing the adhesion force of the adhesive layer. The lower limit of the adhesion energy is not particularly limited, but is usually 0.12J/m ² Preferably 0.14J/m ² 。

In the above measurement of adhesion energy, irradiation of ultraviolet rays is performed from the substrate side. In addition, the adhesion energy was measured using an atomic force microscope. Specifically, the surface of the adhesive layer was pressed and separated at room temperature at a press-in amount of 5nm and a scanning speed of 5Hz using a cantilever (tip radius: 2nm, resonance frequency: 70kHz, spring constant: 0.4N/m) of a silicon nitride material provided on an atomic force microscope. The adhesion energy was calculated by fitting the obtained force curve (horizontal axis represents the deformation of the sample, vertical axis represents the measurement load) to a JKR theoretical formula. The average of the values obtained by measuring 4096 points in 5.mu.m.times.5.mu.m of the surface of the adhesive layer was taken as the adhesive energy (J/m) ² )。

The above adhesion energy can be controlled in the following manner: the adhesive layer was prepared to contain an acrylic resin, further adjusting the amount of polymerized units from HEMA. In particular, the adhesive energy can be controlled within the above range by preparing the adhesive layer such that the content of the polymerized units derived from HEMA is 6 parts by mass or more relative to 100 parts by mass of the total amount of the acrylic resin.

The thickness of the adhesive layer is not particularly limited as long as the peel strength of the adhesive layer after irradiation with ultraviolet rays in a state of being exposed to an air atmosphere is 1600mN/25mm or less as described above, but is preferably less than 100 μm, more preferably 5 to 80 μm, and still more preferably 10 to 70 μm.

The pressure-sensitive adhesive layer is not particularly limited as long as the peel strength after irradiation with ultraviolet light in the state of being exposed to the air atmosphere is 1600mN/25mm or less as described above, but is preferably formed of an acrylic pressure-sensitive adhesive. Further, the adhesive layer is preferably formed of an energy ray curable adhesive. The "energy ray" means ultraviolet rays, electron beams, or the like, and ultraviolet rays are preferably used.

Specific examples of the adhesive are described in detail below, but these specific examples are non-limiting examples, and the adhesive layer of the present invention should not be construed as being limited to these specific examples.

[ adhesive composition ]

As the energy ray-curable adhesive forming the adhesive layer, for example, can be used: an energy ray-curable adhesive composition (hereinafter, also referred to as "X-type adhesive composition") containing an energy ray-curable compound other than the adhesive resin, in addition to the non-energy ray-curable adhesive resin (also referred to as "adhesive resin I"). As the energy ray-curable adhesive, an adhesive composition (hereinafter, also referred to as "Y-type adhesive composition") containing an energy ray-curable adhesive resin (hereinafter, also referred to as "adhesive resin II") having an unsaturated group introduced into a side chain of a non-energy ray-curable adhesive resin as a main component and containing no energy ray-curable compound other than the adhesive resin may be used.

Further, as the energy ray-curable adhesive, an energy ray-curable adhesive composition (hereinafter, also referred to as "XY-type adhesive composition") containing an energy ray-curable compound in addition to the energy ray-curable adhesive resin II, which is a combination of the X-type and the Y-type, can be used.

Among them, an XY type adhesive composition is preferably used. By using the XY-type adhesive composition, the adhesive composition has sufficient adhesive properties before curing, and on the other hand, the peel strength of the semiconductor wafer after curing can be sufficiently reduced.

However, the adhesive may be formed of a non-energy ray-curable adhesive composition which does not cure even when irradiated with energy rays. The non-energy ray-curable adhesive composition contains at least the non-energy ray-curable adhesive resin I, but does not contain the above-mentioned energy ray-curable adhesive resin II and energy ray-curable compound.

In the following description, "adhesive resin" is used as a term for referring to one or both of the adhesive resin I and the adhesive resin II. Specific examples of the adhesive resin include acrylic resins, urethane resins, rubber resins, silicone resins, and the like, and acrylic resins are preferable.

Hereinafter, an acrylic adhesive using an acrylic resin as an adhesive resin will be described in more detail.

An acrylic polymer is used for the acrylic resin. The acrylic polymer is obtained by polymerizing a monomer containing at least an alkyl (meth) acrylate, and contains a structural unit derived from the alkyl (meth) acrylate. The alkyl (meth) acrylate includes alkyl (meth) acrylates having 1 to 20 carbon atoms as an alkyl group, and the alkyl group may be linear or branched. Specific examples of the alkyl (meth) acrylate 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, dodecyl (meth) acrylate, and the like. The alkyl (meth) acrylate may be used singly or in combination of two or more.

In addition, from the viewpoint of improving the adhesive force of the adhesive layer, the acrylic polymer preferably contains a structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms as an alkyl group. The number of carbon atoms of the alkyl (meth) acrylate is preferably 4 to 12, more preferably 4 to 6. The alkyl (meth) acrylate in which the alkyl group has 4 or more carbon atoms is preferably an alkyl acrylate.

In the acrylic polymer, the content of the 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, relative to 100 parts by mass of the total amount of the monomers constituting the acrylic polymer (hereinafter also abbreviated as "total amount of the monomers").

The acrylic polymer is preferably a copolymer containing a structural unit derived from an alkyl (meth) acrylate having 1 to 3 carbon atoms in an alkyl group in order to adjust the elastic modulus, the adhesive property, and the like of the adhesive layer, in addition to a structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms in an alkyl group. 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. The content of the 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 monomer in the acrylic polymer.

The acrylic polymer preferably has a structural unit derived from a functional group-containing monomer in addition to the structural unit derived from the above-mentioned alkyl (meth) acrylate. Examples of the functional group-containing monomer include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. The functional group-containing monomer may be reacted with a crosslinking agent described below to form a crosslinking starting point, or may be reacted with an unsaturated group-containing compound to introduce an unsaturated group into a side chain of the acrylic polymer.

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer. In the present embodiment, it is particularly preferable to use HEMA in an amount of not less than a certain amount as the functional group-containing monomer.

Here, in the adhesive tape of the present embodiment, it is preferable that the adhesive layer contains an acrylic resin, and the content of the polymerized 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. The content of the polymerized units derived from HEMA may be further 10 parts by mass or more or 12 parts by mass or more. In the preparation of the adhesive layer, the peel strength, surface free energy, surface elastic modulus, and adhesion energy of the adhesive can be set within the desired ranges by using the polymer unit content derived from HEMA in the above-described range. The upper limit of the content of the polymerized unit derived from HEMA in the adhesive layer is not particularly limited, but is usually 35 parts by mass, preferably 32 parts by mass, relative to 100 parts by mass of the total amount of the acrylic resin.

In this embodiment, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, or the like other than HEMA may be used alone or in combination of two or more. Among them, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferably used, and hydroxyl group-containing monomers are more preferably used.

Examples of the hydroxyl group-containing monomer include 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, in addition to HEMA; unsaturated alcohols such as vinyl alcohol and allyl alcohol.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and butenoic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, anhydrides thereof, and 2-carboxyethyl methacrylate.

The content of the functional group-containing monomer 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, relative to 100 parts by mass of the total amount of the monomers constituting the acrylic polymer.

In addition to the above, the acrylic polymer may contain structural units derived from monomers copolymerizable with the above acrylic monomers, such as styrene, α -methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

The acrylic polymer can be used as the non-energy ray-curable adhesive resin I (acrylic resin). The energy ray-curable acrylic resin includes: an acrylic resin obtained by reacting the functional group of the acrylic polymer I with a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound).

The unsaturated group-containing compound is a compound having both a substituent capable of bonding to the functional group of the acrylic polymer and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include a (meth) acryloyl group, a vinyl group, an allyl group, and a vinylbenzyl group, and a (meth) acryloyl group is preferable.

Examples of the substituent capable of bonding to the functional group of the unsaturated group-containing compound include an isocyanate group and a glycidyl group. Thus, examples of the unsaturated group-containing compound include (meth) acryloyloxyethyl isocyanate, (meth) acryloyloxyisocyanate, and (meth) glycidyl acrylate.

The unsaturated group-containing compound is preferably reacted with a part of the functional groups of the acrylic polymer, and specifically, 50 to 98 mol% of the functional groups of the acrylic polymer are preferably reacted with the unsaturated group-containing compound, and more preferably 55 to 93 mol% are reacted with the unsaturated group-containing compound. In this way, in the energy ray-curable acrylic resin, a part of the functional group remains without reacting with the unsaturated group-containing compound, and thus it is easy to crosslink it by the crosslinking agent.

The weight average molecular weight (Mw) of the acrylic resin is preferably 30 to 160,40 to 140,50 to 120,000.

(energy ray-curable Compound)

The energy ray-curable compound contained in the X-type or XY-type adhesive composition is preferably a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and cured by irradiation with energy rays.

Examples of such an energy ray-curable compound include oligomers such as trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, and 1, 6-hexanediol (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, and epoxy (meth) acrylate.

Among them, urethane (meth) acrylate oligomer is preferable in view of the fact that the adhesive layer has a relatively high molecular weight and is not likely to lower the shear storage modulus.

The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray-curable compound is preferably 100 to 12000, more preferably 200 to 10000, still more preferably 400 to 8000, particularly preferably 600 to 6000.

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 the 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, relative to 100 parts by mass of the adhesive resin. In the XY-type adhesive composition, since the adhesive resin is energy ray-curable, even if the content of the energy ray-curable compound is small, the peel strength can be sufficiently reduced after the irradiation of the energy ray.

(crosslinking agent)

The adhesive composition preferably further contains a crosslinking agent. The crosslinking agent reacts with, for example, a functional group derived from a functional group-containing monomer contained in the adhesive resin, thereby crosslinking the adhesive resins to each other. Examples of the crosslinking agent include isocyanate-based crosslinking agents such as toluene diisocyanate and hexamethylene diisocyanate and adducts thereof; epoxy crosslinking agents such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents such as hexa [1- (2-methyl) -aziridinyl ] triphosphatriazine (hexa [1- (2-methyl) -aziridinyl ] triphosphatriazine); chelate crosslinking agents such as aluminum chelates. These crosslinking agents may be used singly or in combination of two or more.

Among them, the isocyanate-based crosslinking agent is preferable from the viewpoint of improving the cohesive force and increasing the adhesive force, and from the viewpoint of easy availability, etc.

The blending amount of the crosslinking agent 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, relative to 100 parts by mass of the adhesive resin, from the viewpoint of promoting the crosslinking reaction.

(photopolymerization initiator)

In addition, when the adhesive composition is energy ray curable, it is preferable that the adhesive composition further contains a photopolymerization initiator. By containing the photopolymerization initiator, the curing reaction of the adhesive composition can be sufficiently performed even by an energy ray having a relatively low energy such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones, and more specifically, examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis (2, 4, 6-trimethylbenzoyl) phenyl phosphine oxide, 2-dimethoxy-2-phenylacetophenone, and the like.

These photopolymerization initiators may be used singly or in combination of two or more.

The amount of the photopolymerization initiator blended 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, relative to 100 parts by mass of the adhesive resin.

(other additives)

The adhesive composition may contain other additives within a range not impairing the effect of the present invention. Examples of the other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like. When these additives are blended, the blending amount of the additives is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the adhesive resin.

In addition, from the viewpoint of improving the coatability to the substrate, the buffer layer, or the release sheet, the adhesive composition may be further diluted with an organic solvent to prepare a solution of the adhesive composition.

Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.

The organic solvent may be used as it is for the synthesis of the adhesive resin, or 1 or more organic solvents other than the organic solvent used for the synthesis may be added to uniformly coat the adhesive composition.

Is a base material

The Young's modulus of the substrate at 23℃is preferably 1000MPa or more. When a base material having a Young's modulus of less than 1000MPa is used, the holding performance of the adhesive tape with respect to the semiconductor wafer or the semiconductor chip is lowered, and vibration and the like during back grinding cannot be suppressed, so that chipping and breakage of the semiconductor chip are likely to occur. On the other hand, by setting the Young's modulus of the base material at 23℃to 1000MPa or more, the holding performance of the adhesive tape for the semiconductor wafer or the semiconductor chip is improved, and chipping and breakage of the semiconductor chip can be prevented by suppressing vibration and the like at the time of back grinding. In addition, the stress when the adhesive tape is peeled from the semiconductor chip can be reduced, and chip chipping and breakage occurring when the adhesive tape is peeled can be prevented. Further, the workability in attaching the adhesive tape to the semiconductor wafer can be improved. From such a viewpoint, the Young's modulus of the substrate at 23℃is more preferably 1800 to 30000MPa, and still more preferably 2500 to 6000MPa.

The thickness of the base material is not particularly limited, but is preferably 110 μm or less, more preferably 15 to 110 μm, and still more preferably 20 to 105 μm. The peel strength of the adhesive tape can be easily controlled by setting the thickness of the base material to 110 μm or less. In addition, when the thickness is 15 μm or more, the substrate easily functions as a support for the adhesive tape.

The material of the base material is not particularly limited as long as the above physical properties are satisfied, and various resin films can be used. Examples of the substrate having a Young's modulus at 23℃of 1000MPa or more include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and wholly aromatic polyesters; polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, biaxially oriented polypropylene and other resin films.

Among these resin films, one or more films selected from the group consisting of polyester films, polyamide films, polyimide films, and biaxially oriented polypropylene films are preferable, polyester films are more preferable, and polyethylene terephthalate films are further preferable.

In addition, the base material may contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, and the like, within a range that does not impair the effects of the present invention. The substrate may be transparent or opaque, and may be colored or vapor deposited as needed.

In addition, at least one surface of the substrate may be subjected to an adhesion treatment such as corona treatment in order to improve adhesion to at least one of the buffer layer and the adhesive layer. The substrate may have an easily adhesive layer formed on at least one surface of the resin film.

The composition for forming the easy-to-adhere layer is not particularly limited, and examples thereof include compositions containing polyester resins, urethane resins, polyester urethane resins, acrylic resins, and the like. The composition for forming an easy-to-bond layer may contain a crosslinking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, an anticorrosive agent, a pigment, a dye, and the like, as necessary.

The thickness of the pressure-sensitive adhesive layer is preferably 0.01 to 10. Mu.m, more preferably 0.03 to 5. Mu.m. In addition, since the thickness of the easy-to-adhere layer in the embodiment of the present application is small relative to the thickness of the base material, the thickness of the resin film having the easy-to-adhere layer is substantially the same as the thickness of the base material. In addition, since the material of the easy-to-adhere layer is soft, the young's modulus is less affected, and even when the easy-to-adhere layer is provided, the young's modulus of the base material is substantially the same as that of the resin film.

For example, the young's modulus of the substrate can be controlled by selection of the resin composition, addition of a plasticizer, stretching conditions at the time of producing a resin film, and the like. Specifically, when a polyethylene terephthalate film is used as a substrate, if the content of the ethylene component in the copolymer component increases, the young's modulus of the substrate tends to decrease. In addition, if the blending amount of the plasticizer is increased relative to the resin composition constituting the base material, the young's modulus of the base material tends to be lowered.

Buffer layer(s)

The adhesive tape of the present embodiment may also have a buffer layer. The buffer layer may be provided on at least one surface of the base material, or may be provided on both surfaces of the base material. In addition, an adhesive layer may be provided on one surface of the base material, and a buffer layer may be provided on the other surface of the base material.

The buffer layer relaxes stress during back grinding of the semiconductor wafer, and prevents occurrence of cracks and chipping in the semiconductor wafer. After the adhesive tape is attached to the semiconductor wafer and cut along the outer periphery, the semiconductor wafer is placed on a chuck table (chuck table) via the adhesive tape and back-polished, and the adhesive tape has a buffer layer as a constituent layer, whereby the semiconductor wafer can be easily held on the chuck table appropriately.

The buffer layer is a soft layer compared to the substrate. Therefore, the Young's modulus of the buffer layer at 23℃is less than the Young's modulus of the substrate at 23 ℃. Specifically, the Young's modulus of the buffer layer at 23℃is preferably less than 1000MPa, more preferably 700MPa or less, and still more preferably 500MPa or less.

The thickness of the buffer layer is preferably 1 to 100. Mu.m, more preferably 5 to 80. Mu.m, still more preferably 10 to 60. Mu.m. By setting the thickness of the buffer layer to the above range, the buffer layer can appropriately relax the stress at the time of back polishing.

The buffer layer is preferably a cured product of a composition for forming a buffer layer containing an energy ray-polymerizable compound. The layer may be a layer containing a polyolefin resin film or a layer containing polyether as a main agent.

The components contained in the layer formed from the composition for forming a buffer layer containing an energy ray-polymerizable compound and the components contained in the layer containing a polyolefin resin film will be described in order.

< layer formed of composition for Forming buffer layer containing energy ray-polymerizable Compound >)

The composition for forming a buffer layer containing the energy ray-polymerizable compound can be cured by irradiation with energy rays.

More specifically, the composition for forming a buffer layer containing the energy ray-polymerizable compound preferably contains a urethane (meth) acrylate (a 1). Further, it is more preferable that the composition for forming a buffer layer further contains a polymerizable compound (a 2) having an alicyclic group or heterocyclic group having 6 to 20 ring-forming atoms and/or a polymerizable compound (a 3) having a functional group, in addition to the above (a 1). The composition for forming a buffer layer may contain a polyfunctional polymerizable compound (a 4) in addition to the above-mentioned components (a 1) to (a 3). The composition for forming a buffer layer preferably contains a photopolymerization initiator, and may contain other additives and resin components within a range that does not impair the effects of the present invention.

The components contained in the composition for forming a buffer layer containing an energy ray-polymerizable compound will be described in detail below.

(urethane (meth) acrylate (a 1))

The urethane (meth) acrylate (a 1) is a compound having at least a (meth) acryloyl group and a urethane bond, and has a property of being polymerized and cured by irradiation with energy rays. The urethane (meth) acrylate (a 1) is an oligomer or a polymer.

The weight average molecular weight (Mw) of the component (a 1) is preferably 1,000 ～ 100,000, more preferably 2,000 to 60,000, and further preferably 10,000 ～ 30,000. The number of (meth) acryloyl groups (hereinafter also referred to as "functional group number") in the component (a 1) may be monofunctional, difunctional, or trifunctional or more, and is preferably monofunctional or difunctional.

The component (a 1) can be obtained, for example, by reacting a polyol compound with a polyisocyanate compound, and reacting the resulting terminal isocyanate urethane prepolymer with a (meth) acrylate having a hydroxyl group. In addition, the component (a 1) may be used singly or in combination of two or more.

The polyol compound as the raw material of the component (a 1) is not particularly limited as long as it is a compound having two or more hydroxyl groups. Specific examples of the polyol compound include alkylene glycol, polyether polyol, polyester polyol, and polycarbonate polyol. Among them, polyester polyols or polycarbonate polyols are preferable.

The polyol compound may be any of a difunctional diol, a trifunctional triol, and a tetrafunctional or higher polyol, and is preferably a difunctional diol, more preferably a polyester diol or a polycarbonate diol.

Examples of the polyisocyanate compound 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 ' -dimethylcyclohexane diisocyanate; aromatic diisocyanates such as 4,4' -diphenylmethane diisocyanate, toluene diisocyanate, xylylene diisocyanate, dimethylbiphenyl diisocyanate, tetramethylene xylylene diisocyanate, and 1, 5-naphthalene diisocyanate.

Among them, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable.

The urethane (meth) acrylate (a 1) can be obtained by reacting the polyol compound with the polyisocyanate compound, and reacting the terminal isocyanate urethane prepolymer thus obtained with a (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 a hydroxyl group and a (meth) acryloyl group in one molecule.

Specific examples of the (meth) acrylic acid ester having a hydroxyl group include 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-phenoxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and the like; hydroxyl group-containing (meth) acrylamides such as N-methylol (meth) acrylamides; and a reactant obtained by reacting (meth) acrylic acid with vinyl alcohol, vinylphenol, and diglycidyl ester of bisphenol A.

Among them, hydroxyalkyl (meth) acrylates are preferable, and 2-hydroxyethyl (meth) acrylate is more preferable.

As the conditions for reacting the terminal isocyanate urethane prepolymer with the (meth) acrylate having a hydroxyl group, the conditions for reacting at 60 to 100℃for 1 to 4 hours in the presence of a solvent and a catalyst added as required are preferable.

The content of the component (a 1) in the composition for forming a buffer layer is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

(polymerizable Compound (a 2) having an alicyclic group or heterocyclic group having 6 to 20 ring members)

The component (a 2) is a polymerizable compound having an alicyclic group or heterocyclic group having 6 to 20 ring members, and is preferably a compound having at least one (meth) acryloyl group, more preferably a compound having one (meth) acryloyl group. By using the component (a 2), the film forming property of the obtained composition for forming a buffer layer can be improved.

The definition of the component (a 2) and the definition of the component (a 3) described later have a repeating part, but the repeating part is included in the component (a 3). For example, a compound having at least one (meth) acryloyl group, an alicyclic group or heterocyclic group having 6 to 20 ring members, and a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group is included in the definition of both the component (a 2) and the component (a 3), but in the present invention, the compound is regarded as being included in the component (a 3).

The number of ring-forming atoms of the alicyclic group or heterocyclic group of the component (a 2) is preferably 6 to 20, more preferably 6 to 18, still more preferably 6 to 16, particularly preferably 7 to 12. Examples of the atoms forming the ring structure of the heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

The number of ring-forming atoms means the number of atoms constituting the ring itself of a compound having a structure in which atoms are bonded in a cyclic manner, and atoms not constituting the ring (for example, hydrogen atoms bonded to atoms constituting the ring), atoms contained in a substituent when the ring is substituted with a substituent, and the like are not included in the number of ring-forming atoms.

Specific examples of the component (a 2) include alicyclic group-containing (meth) acrylates such as isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantyl (meth) acrylate, and the like; heterocyclic group-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate and morpholino (meth) acrylate.

In addition, the component (a 2) may be used singly or in combination of two or more.

Among alicyclic group-containing (meth) acrylates, isobornyl (meth) acrylate is preferred, and among heterocyclic group-containing (meth) acrylates, tetrahydrofurfuryl (meth) acrylate is preferred.

The content of the component (a 2) in the composition for forming a buffer layer is preferably 10 to 80 parts by mass, more preferably 20 to 70 parts by mass, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

(polymerizable Compound (a 3) having functional group)

The component (a 3) is a polymerizable compound having a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group, and is preferably a compound having at least one (meth) acryloyl group, and more preferably a compound having one (meth) acryloyl group.

The component (a 3) has good compatibility with the component (a 1), and the viscosity of the composition for forming a buffer layer can be easily adjusted to an appropriate range. In addition, even if the buffer layer is made thin, the buffer performance is good.

Examples of the component (a 3) include hydroxyl group-containing (meth) acrylates, epoxy group-containing compounds, amide group-containing compounds, amino group-containing (meth) acrylates, and the like.

Examples of the hydroxyl group-containing (meth) acrylate 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, phenylpropyl (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate.

Examples of the epoxy group-containing compound include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether, and the like, and among them, epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and the like are preferable.

Examples of the amide group-containing compound include (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxymethyl propane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

Examples of the amino group-containing (meth) acrylate include a primary amino group-containing (meth) acrylate, a secondary amino group-containing (meth) acrylate, and a tertiary amino group-containing (meth) acrylate.

Among them, hydroxyl group-containing (meth) acrylates are preferable, and hydroxyl group-containing (meth) acrylates having an aromatic ring such as phenyl hydroxypropyl (meth) acrylate are more preferable.

In addition, the component (a 3) may be used singly or in combination of two or more.

In order to improve the film forming property of the composition for forming a buffer layer, the content of the component (a 3) in the composition for forming a buffer layer 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, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

The content ratio [ (a 2)/(a 3) ] of the component (a 2) to the component (a 3) in the composition for forming a buffer layer is preferably 0.5 to 3.0, more preferably 1.0 to 3.0, still more preferably 1.3 to 3.0, and particularly preferably 1.5 to 2.8.

(multifunctional polymerizable Compound (a 4))

The polyfunctional polymerizable compound means a compound having two or more photopolymerizable unsaturated groups. The photopolymerizable unsaturated group is a functional group having a carbon-carbon double bond, and examples thereof include a (meth) acryloyl group, a vinyl group, an allyl group, and a vinylbenzyl group. Two or more photopolymerizable unsaturated groups may be combined. The photopolymerizable unsaturated group in the polyfunctional polymerizable compound is reacted with the (meth) acryloyl group in the component (a 1) or the photopolymerizable unsaturated group in the component (a 4) is reacted with each other, whereby a three-dimensional network structure (crosslinked structure) can be formed. When a polyfunctional polymerizable compound is used, a crosslinked structure formed by irradiation with energy rays is more likely to be increased than when a compound having only one photopolymerizable unsaturated group is used.

The definition of the component (a 4) and the definitions of the components (a 2) and (a 3) described above have a repeating part, but the repeating part is included in the component (a 4). For example, a compound having an alicyclic group or heterocyclic group having 6 to 20 ring atoms and having two or more (meth) acryloyl groups is included in the definition of both the component (a 4) and the component (a 2), but in the present invention, the compound is regarded as being included in the component (a 4). In addition, a compound containing a functional group such as a hydroxyl group, an epoxy group, an amide group, or an amino group and having two or more (meth) acryloyl groups is included in the definition of both the component (a 4) and the component (a 3), but in the present invention, the compound is regarded as being included in the component (a 4).

From the above point of view, the number of photopolymerizable unsaturated groups (the number of functional groups) in the polyfunctional polymerizable compound is preferably 2 to 10, more preferably 3 to 6.

The weight average molecular weight of the component (a 4) is preferably 30 to 40000, more preferably 100 to 10000, and even more preferably 200 to 1000.

Specific examples of the component (a 4) include 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 tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, vinyl (meth) acrylate, divinyl adipate, and N, N' -methylenebis (meth) acrylamide.

In addition, the component (a 4) may be used singly or in combination of two or more.

Among them, dipentaerythritol hexa (meth) acrylate is preferable.

The content of the component (a 4) in the composition for forming a buffer layer 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, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

(polymerizable Compound (a 5) other than Components (a 1) to (a 4))

The buffer layer-forming composition may contain other polymerizable compounds (a 5) than the above-mentioned components (a 1) to (a 4) within a range that does not impair the effects of the present invention.

Examples of the component (a 5) include alkyl (meth) acrylates having an alkyl group having 1 to 20 carbon atoms; vinyl compounds such as styrene, 2-ethyleneoxyethanol, 4-hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone and N-vinylcaprolactam. The component (a 5) may be used alone or in combination of two or more.

The content of the component (a 5) in the composition for forming a buffer layer is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, still more preferably 0 to 5 parts by mass, and particularly preferably 0 to 2 parts by mass, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

(photopolymerization initiator)

In order to shorten the time for polymerization by light irradiation and to reduce the amount of light irradiation when forming the buffer layer, it is preferable that the buffer layer-forming composition further contains a photopolymerization initiator.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones, and more specifically, examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like.

These photopolymerization initiators can be used singly or in combination of two or more.

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

(other additives)

The buffer layer-forming composition may contain other additives within a range that does not impair the effects of the present invention. Examples of the other additives include antistatic agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes. When these additives are blended, the content of each additive in the composition for forming a buffer layer is preferably 0.01 to 6 parts by mass, more preferably 0.1 to 3 parts by mass, relative to 100 parts by mass of the total amount of the energy ray-polymerizable compounds.

(resin component)

The composition for forming a buffer layer may contain a resin component within a range that does not impair the effects of the present invention. Examples of the resin component include a polyene-thiol resin; polyolefin resins such as polybutene, polybutadiene and polymethylpentene; thermoplastic resins such as styrene-based copolymers, and the like.

The content of these resin components in the composition for forming a buffer layer is preferably 0 to 20 parts by mass, more preferably 0 to 10 parts by mass, still more preferably 0 to 5 parts by mass, and particularly preferably 0 to 2 parts by mass, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

The buffer layer formed from the composition for forming a buffer layer containing an energy ray-polymerizable compound is obtained by irradiating the composition for forming a buffer layer having the above composition with an energy ray to polymerize and cure the composition. That is, the buffer layer is a cured product of the buffer layer forming composition.

Thus, the buffer layer contains polymerized units derived from component (a 1). The buffer layer preferably contains a polymerized unit derived from the component (a 2) and/or a polymerized unit derived from the component (a 3). Further, the polymer unit derived from the component (a 4) and/or the polymer unit derived from the component (a 5) may be contained. The content ratio of each polymer unit in the buffer layer generally corresponds to the ratio (addition ratio) of each component constituting the composition for forming a buffer layer. For example, when the content of the component (a 1) in the composition for forming a buffer layer is 10 to 70 parts by mass relative to the total amount (100 parts by mass) of the composition for forming a buffer layer, the buffer layer contains 10 to 70 parts by mass of the polymerized unit derived from the component (a 1). When the content of the component (a 2) in the composition for forming a buffer layer is 10 to 80 parts by mass relative to the total amount (100 parts by mass) of the composition for forming a buffer layer, the buffer layer contains 10 to 80 parts by mass of the polymerized unit derived from the component (a 2). The same applies to the components (a 3) to (a 5).

< layer comprising polyolefin resin film >

The buffer layer may be formed of a layer including a polyolefin resin film.

When the buffer layer is a layer containing a polyolefin resin film, the stress relaxation property may be lower than when the buffer layer is a layer formed from a composition for forming a buffer layer containing an energy ray polymerizable compound. At this time, the adhesive tape having a buffer layer formed of a layer containing a polyolefin resin film on one side of the substrate may be warped. Although the buffer layer formed of the layer containing the polyolefin resin film may be provided on at least one surface side of the substrate, it is preferable to provide the buffer layer formed of the layer containing the polyolefin resin film on both surfaces of the substrate in view of preventing such a problem.

The polyolefin resin is not particularly limited, and examples thereof include very low density polyethylene (VLDPE, density: 880 kg/m) ³ Above and less than 910kg/m ³ ) Low density polyethylene (LDPE, density: 910kg/m ³ Above and below 930kg/m ³ ) Medium density polyethylene (MDPE, density: 930kg/m ³ Above and below 942kg/m ³ ) High density polyethylene (HDPE, density: 942kg/m ³ The above), and the like, polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin-based elastomers (TPOs), cycloolefin resins, ethylene-vinyl acetate copolymers (EVA), ethylene-vinyl acetate-maleic anhydride copolymers, ethylene- (meth) acrylic acid ester-maleic anhydride copolymers, and the like.

These polyolefin resins can be used singly or in combination of two or more.

Among the above polyolefin resins, polyethylene resins are preferred, and low-density polyethylene is more preferred, from the viewpoint of obtaining a buffer layer having specific physical properties.

The buffer layer may contain additives such as plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, and catalysts, within a range that does not impair the effects of the present invention. The buffer layer may be transparent or opaque, and may be colored or vapor deposited as needed.

Is of the stripping sheet

The release sheet may be attached to the surface of the adhesive tape. Specifically, the release sheet is attached to the surface of the adhesive layer of the adhesive tape. The release sheet is attached to the surface of the adhesive layer, thereby protecting the adhesive layer during transportation and storage. The release sheet is releasably attached to the adhesive tape and is peeled from the adhesive tape prior to use of the adhesive tape (i.e., prior to wafer attachment).

As the release sheet, a release sheet having at least one surface subjected to a release treatment is used, and specifically, a release sheet obtained by applying a release agent to the surface of a base material for a release sheet, and the like are exemplified.

As the base material for the release sheet, a resin film is preferable, and examples of the resin constituting the resin film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; polyolefin resins such as polypropylene resins and polyethylene resins. Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release sheet is not particularly limited, but is preferably 10 to 200. Mu.m, more preferably 20 to 150. Mu.m.

Method for producing adhesive tape

The method for producing the adhesive tape of the present invention is not particularly limited, and the adhesive tape can be produced by a known method.

For example, the method for producing an adhesive tape having a base material, an adhesive layer provided on one surface side of the base material, and a buffer layer provided on the other surface side of the base material is as follows.

When the buffer layer is formed of the composition for forming a buffer layer containing an energy ray-polymerizable compound, the composition for forming a buffer layer is applied to a release sheet and cured, and the release sheet is removed by bonding the buffer layer and the substrate, thereby obtaining a laminate of the buffer layer and the substrate. When the buffer layer is a layer including a polyolefin resin film, the buffer layer is bonded to the substrate, and a laminate of the buffer layer and the substrate is obtained.

Then, the adhesive layer provided on the release sheet is bonded to the substrate side of the laminate, whereby an adhesive tape having the release sheet attached to the surface of the adhesive layer can be produced. The release sheet attached to the surface of the adhesive layer may be suitably peeled off before the adhesive tape is used.

As a method for forming the adhesive layer on the release sheet, an adhesive (adhesive composition) may be directly coated on the release sheet by a known coating method, and the coated film may be dried by heating, thereby forming the adhesive layer.

In addition, an adhesive (adhesive composition) may be directly applied to one surface of the substrate to form an adhesive layer. Examples of the method for applying the adhesive include a spray coating method, a bar coating method, a blade coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method, which are described in the method for producing the buffer layer.

As a method for forming the buffer layer on the release sheet, a buffer layer can be formed by directly applying a buffer layer forming composition to the release sheet by a known coating method to form a coating film, and irradiating the coating film with energy rays. The buffer layer-forming composition may be directly applied to one surface of a substrate, and the buffer layer may be formed by drying by heating or by irradiating the coating film with energy rays.

Examples of the method for applying the composition for forming a buffer layer include spin coating, spray coating, bar coating, blade coating, roll coating, blade coating, die coating, and gravure coating. In order to improve the coatability, the composition for forming a buffer layer may be coated on a release sheet in the form of a solution by blending an organic solvent.

When the composition for forming a buffer layer contains an energy ray polymerizable compound, the buffer layer is preferably formed by irradiating a coating film of the composition for forming a buffer layer with energy rays and curing the coating film. The curing of the buffer layer may be performed once or may be performed in a plurality of times. For example, the coating film on the release sheet may be completely cured to form a buffer layer and then bonded to the substrate, or the coating film may be incompletely cured to form a buffer layer forming film in a semi-cured state, and the buffer layer forming film may be bonded to the substrate and then irradiated with energy rays again to be completely cured to form a buffer layer. The energy ray irradiated in the curing treatment is preferably ultraviolet rays. In addition, in the case of curing, the coating film of the composition for forming a buffer layer may be cured by irradiation with energy rays in a state where the coating film is exposed, but it is preferable that the coating film is covered with a release sheet, a base material, or the like and the coating film is cured by irradiation with energy rays in a state where the coating film is not exposed.

When the buffer layer is a layer containing a polyolefin resin film, the buffer layer can be bonded to the substrate by lamination by extrusion. Specifically, the polyolefin resin constituting the buffer layer is melted and kneaded using a T-die film forming machine or the like, and the melted polyolefin resin is extrusion-laminated to one surface side of the base material while the base material is moved at a constant speed. The buffer layer may be directly laminated on the substrate by heat sealing or the like. Further, the laminate may be laminated via an easy-to-adhere layer by a dry lamination method or the like.

In addition, in the method for producing an adhesive tape having a buffer layer provided on both surfaces of a substrate, for example, a laminate of the buffer layer, the substrate, and the buffer layer laminated in this order may be obtained by the above method, and then the adhesive layer may be formed on the buffer layer side of one side.

Method for manufacturing semiconductor device

The adhesive tape of the present invention is preferably applied to the surface of a semiconductor wafer and used for back grinding the wafer. The adhesive tape of the present invention is more preferably used for DBG in which back grinding of a wafer and singulation of the wafer are performed simultaneously. The adhesive tape of the present invention is particularly preferably used for LDBG which can obtain a chip set having a small kerf width when singulating a semiconductor wafer. In addition, in the case of the optical fiber,

"chipset" refers to a plurality of semiconductor chips held on the adhesive tape of the present invention in a regular array in a wafer shape.

As a non-limiting example of use of the adhesive tape, a method for manufacturing a semiconductor device will be described in more detail below.

Specifically, the method for manufacturing a semiconductor device includes at least the following steps 1 to 4.

Step 1: attaching the adhesive tape to the surface of the semiconductor wafer, and adhering the adhesive tape along the outer Zhou Qieduan of the semiconductor wafer;

step 2: forming a trench from the front surface side of the semiconductor wafer or forming a modified region in the semiconductor wafer from the front surface or the back surface of the semiconductor wafer;

and step 3: polishing the semiconductor wafer, on the front surface of which the adhesive tape is attached and the grooves or modified regions are formed, from the back surface side, and singulating the semiconductor wafer into a plurality of chips with the grooves or modified regions as a starting point;

and 4, step 4: and a step of peeling the adhesive tape from the singulated semiconductor wafer (i.e., the plurality of semiconductor chips).

Each step of the method for manufacturing a semiconductor device will be described in detail below.

(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 periphery of the semiconductor wafer. The adhesive tape is attached to cover the semiconductor wafer and the peripheral work table extending the periphery thereof. Then, the adhesive tape is cut along the outer periphery of the semiconductor wafer using a cutter or the like. The cutting speed is usually 10 to 300mm/s. The temperature of the cutter blade during cutting can be room temperature, and the cutter blade can be heated for cutting.

The present step may be performed before step 2 described later, or may be performed after step 2. For example, when forming the modified region in the semiconductor wafer, the step 1 is preferably performed before the step 2. On the other hand, when grooves are formed on the surface of the semiconductor wafer by dicing or the like, step 1 is performed after step 2. That is, in this step 1, an adhesive tape is attached to the surface of the wafer having the grooves formed in the step 2 described later.

The semiconductor wafer used in the present manufacturing method may be a silicon wafer, or may be a wafer of gallium arsenide, silicon carbide, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or the like, or a glass wafer, or the like. The thickness of the semiconductor wafer before polishing is not particularly limited, but is usually about 500 to 1000 μm. In addition, semiconductor wafers typically have circuits formed on their surfaces. The circuit can be formed on the wafer surface by various methods including a conventional general method such as an etching method and a lift-off method.

(Process 2)

In step 2, a trench is formed from the front surface side of the semiconductor wafer, or a modified region is formed in the semiconductor wafer from the front surface or the back surface of the semiconductor wafer.

The trench formed in this process is a trench having a shallower depth than the thickness of the semiconductor wafer. The grooves may be formed by dicing using a conventionally known wafer dicing apparatus or the like. In step 3 described later, the semiconductor wafer is divided into a plurality of semiconductor chips along the grooves.

The modified region is an embrittled portion of the semiconductor wafer, and is a region which becomes a starting point of the semiconductor wafer to be singulated into semiconductor chips due to breakage of the semiconductor wafer caused by: the semiconductor wafer becomes thin or a force due to polishing is applied due to polishing in the polishing process. That is, in step 2, grooves and modified regions are formed along dividing lines when the semiconductor wafer is divided and singulated into semiconductor chips in step 3 described below.

The modified region is formed by irradiating a laser beam focused on the inside of the semiconductor wafer with a focus, and the modified region is formed inside the semiconductor wafer. The irradiation of the laser beam may be performed from the front surface side or the back surface side of the semiconductor wafer. In the case of forming the modified region, when the step 2 is performed after the step 1 and the laser irradiation is performed from the wafer surface, the semiconductor wafer is irradiated with the laser light through the adhesive tape.

The semiconductor wafer on which the adhesive tape is attached and the grooves or modified regions are formed is placed on a chuck table, and is sucked and held on the chuck table. At this time, the surface side of the semiconductor wafer is disposed and adsorbed on the stage side.

(step 3)

After steps 1 and 2, the back surface of the semiconductor wafer on the chuck table is polished to singulate the semiconductor wafer into a plurality of semiconductor chips.

Here, when forming a trench in a semiconductor wafer, back grinding is performed so as to thin the semiconductor wafer at least to a position reaching the bottom of the trench. By this back grinding, the grooves become cuts through the wafer, and the semiconductor wafer is divided by the cuts, and singulated into individual semiconductor chips.

On the other hand, when forming the modified region, the polished surface (wafer back surface) may reach the modified region by polishing, but may not reach the modified region precisely. That is, the semiconductor wafer may be polished to a position close to the modified region, and broken from the modified region, and singulated into semiconductor chips. For example, the actual singulation of the semiconductor chips may be performed by stretching a pick-up tape after attaching the pick-up tape described later.

Further, after the back grinding is finished, dry polishing may be performed before picking up the chip.

The singulated semiconductor chips may have a square shape or an elongated shape such as a rectangular shape. The thickness of the singulated semiconductor chip is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. The thickness of the singulated semiconductor chip is easily made to be 50 μm or less, more preferably 10 to 45 μm, by providing the modified region inside the wafer with the laser light and singulating the wafer with the stress or the like at the time of wafer back surface polishing. In addition, the size of the singulated semiconductor chips is not particularly limited, and the chip size is preferably less than 600mm ² More preferably less than 400mm ² More preferably less than 300mm ² 。

When the adhesive tape of the present invention is used, even in such a thin and/or small semiconductor chip, cracks in the semiconductor chip can be prevented from occurring when the adhesive tape is peeled off (step 4) below.

(Process 4)

The adhesive tape is peeled from the singulated semiconductor wafers (i.e., the plurality of semiconductor chips neatly arranged in a wafer shape). The present step is performed, for example, by the following method.

First, when the adhesive layer of the adhesive tape is formed of an energy ray curable adhesive, the adhesive layer is cured by irradiation of energy rays. Then, a pick-up tape is attached to the back side of the singulated semiconductor wafer to perform position and orientation alignment in a pickable manner. At this time, an annular frame (ring frame) disposed on the outer peripheral side of the wafer is also attached to the pickup tape, and the outer peripheral edge portion of the pickup tape is fixed to the annular frame. The wafer and the annular frame can be attached to the pick-up tape at the same time, or at different times. Next, the adhesive tape is peeled from the plurality of semiconductor chips held on the pick-up tape.

Then, a plurality of semiconductor chips on the pickup tape are picked up and fixed on a substrate or the like, and a semiconductor device is manufactured.

The pickup tape is not particularly limited, and may be constituted by an adhesive tape including a base material and an adhesive layer provided on at least one surface of the base material.

In addition, an adhesive tape may be used instead of the pick-up tape. Examples of the 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 composed of an adhesive layer and a release sheet having functions of both the dicing tape and the die bonding tape. That is, the present embodiment may include a step of attaching dicing die attach tape to the back surface of the semiconductor wafer. In addition, a film-like adhesive may be attached to the back side of the singulated semiconductor wafer before the pick-up tape is attached. When a film-like adhesive is used, the film-like adhesive may be formed in the same shape as the wafer.

Here, when the adhesive layer of the adhesive tape is formed of an energy ray curable adhesive, if energy rays are irradiated, a portion of the adhesive layer that adheres to the wafer is cured, and the adhesive force of the portion is sufficiently reduced. However, in a portion of the adhesive tape which is not adhered to the wafer and is exposed to the atmosphere, curing of the adhesive is generally hindered by oxygen in the atmosphere, and even if the adhesive tape is irradiated with energy rays such as ultraviolet rays, the adhesive force is not sufficiently lowered. Therefore, as shown in fig. 3, when the thickness of the semiconductor wafer has been extremely thinned to about 30 μm by back grinding, if dicing die-bonding tape or the like is attached to the back surface of the semiconductor wafer, an uncured portion of the adhesive layer of the adhesive tape attached to the surface of the semiconductor wafer contacts and adheres to the adhesive layer of the dicing die-bonding tape or the like. When the adhesive tape attached to the dicing die bonding tape or the like is to be peeled off, the adhesive tape and the dicing die bonding tape are integrated, and the dicing die bonding tape is also bent along with the bending of the adhesive tape, and the wafer, the chip, or the like interposed between the adhesive tape and the dicing die bonding tape is also bent at the same time. As a result, cracks are likely to occur in the chip. In addition, the adhesive layer such as dicing die bonding tape may be broken by bending, and fragments thereof may be peeled off.

On the other hand, with the adhesive tape of the present embodiment, it is possible to prevent cracks from occurring in the semiconductor chip when the adhesive tape is peeled off. Fig. 5 is a schematic view of a laminate in which dicing die attach tape 30 is further attached to semiconductor wafer 20 after back grinding to which the adhesive tape of the present embodiment is attached. Fig. 5 shows a case where dicing die attach tape 30 is attached to semiconductor wafer 20 which is subjected to back grinding and extremely thinned to a thickness of about 30 μm. In the adhesive tape of the present embodiment, even when the adhesive layer is exposed to the air atmosphere, the adhesive force can be sufficiently reduced by irradiation of energy rays. Therefore, as shown in fig. 5, when the thickness of the semiconductor wafer is extremely reduced to about 30 μm by back grinding, even if a part of the adhesive layer of the adhesive tape attached to the surface of the semiconductor wafer is in contact with the adhesive layer of the dicing die bonding tape or the like, both will not be attached. Therefore, the adhesive tape is not integrated with the dicing die bonding tape but can be peeled off. As a result, cracking of the chip can be suppressed.

When an adhesive tape is used or a film-like adhesive is attached to the back side of a singulated semiconductor wafer before attaching a pick-up tape, a plurality of semiconductor chips located on the adhesive tape and the pick-up tape are picked up together with an adhesive layer divided into the same shape as the semiconductor chips. Then, the semiconductor chip is fixed on a substrate or the like via an adhesive layer, and a semiconductor device is manufactured. The adhesive layer is divided by laser light and expansion.

As described above, the adhesive tape of the present invention is used for the method of singulating semiconductor wafers by DBG or LDBG, but the adhesive tape of the present invention can be suitably used for LDBG which can obtain a chip set having a smaller kerf width and a thinner kerf when singulating semiconductor wafers. The adhesive tape of the present invention can be used for general back grinding, and can also be used for temporarily holding a work piece when processing glass, ceramics, or the like. The present invention can also be used as various removable adhesive tapes.

Examples

Hereinafter, the present invention will be described in further detail based on examples, but the present invention is not limited by these examples.

The measurement method and the evaluation method are as follows. The results are shown in Table 1.

[ peel Strength ]

An adhesive tape (width: 25 mm) for semiconductor processing comprising a base material and an adhesive layer was irradiated with ultraviolet light (manufactured by LINTEC Corporation under the device name "RAD 2000") in a state in which one surface of the adhesive layer was exposed to an atmosphere, with an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The condition of (2) irradiating ultraviolet rays to the adhesive tape from the substrate side. After a PMMA plate (manufactured by Mitsubishi Chemical Corporation of thickness 2mm, width 70mm and length 150mm, "ACRYLITE L001") was attached to the exposed surface of the adhesive layer by a 2kg roller at 23℃and 50% RH and left for 30 minutes, the peel strength of the adhesive tape at 180℃was measured at a measurement temperature of 25℃and a peeling speed of 300 mm/min. The measurement was performed twice under the same conditions, and the average value thereof is shown in Table 1.

[ peeling evaluation ]

The adhesive tape was attached to a silicon wafer having a diameter of 12 inches and a thickness of 775 μm using a tape bonder for back grinding (manufactured by LINTEC Corporation under the device name "RAD-3510F/12"), and was adhered along the outer side Zhou Qieduan of the silicon wafer. For the silicon wafer, a laser beam having a wavelength of 1342nm was irradiated from the surface of the silicon wafer using a laser cutter (manufactured by DISCO Corporation under the device name "DFL 7361") so thatThe modified region was formed in the silicon wafer so that the chip size became 5mm×5 mm. Then, the back surface of the silicon wafer was polished using a polishing machine (manufactured by DISCO Corporation under the device name "DGP 8760") so that the thickness after polishing was 30 μm. At this time, the adhesive tape was set to a size covering the outer periphery of the polished silicon wafer to a size 1.0mm larger than the outer periphery of the silicon wafer. Using an ultraviolet irradiation device (manufactured by LINTEC Corporation under the device name "RAD 2000") with an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The condition of (2) irradiating ultraviolet rays to the adhesive tape from the substrate side, namely the surface side of the silicon wafer. The adhesive layer of the dicing tape (manufactured by LINTEC Corporation, LD 01D-07) was attached to the back surface of the silicon wafer while heating to 60 ℃ using a tape dispenser (manufactured by LINTEC Corporation, device name "ADWILLRAD-2700"). The adhesive tape was peeled off. The degree of peeling of the adhesive layer of the dicing die-bonding tape at this time was observed and evaluated by the following criteria.

A: the peeling area is less than 70%.

B: the peeling area is 70% or more and less than 97%.

C: the peeling area was 97% or more.

[ surface free energy ]

An adhesive tape for semiconductor processing was prepared by exposing one surface of an adhesive layer to an air atmosphere using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name "RAD 2000") at an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The condition of (2) irradiating ultraviolet rays to the adhesive tape from the substrate side. The contact angle (measurement temperature: 25 ℃ C.) was measured by the horizontal drop method using diiodomethane, 1-bromonaphthalene and distilled water as droplets using a contact angle measuring instrument (manufactured by Kyowa Interface science Co., ltd., apparatus name "DM-70"), and the contact angle was measured with reference to JIS R3257:1999, and the surface free energy (mJ/m) was calculated by the Kitazaki-Hata method based on the value of the contact angle ² )。

[ surface elastic modulus ]

For an adhesive tape for semiconductor processing, a purple adhesive tape is used in a state in which one surface of an adhesive layer is exposed to an atmosphereAn external-ray irradiation device (manufactured by LINTEC Corporation, device name "RAD 2000") was used with an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The condition of (2) irradiating ultraviolet rays to the adhesive tape from the substrate side. Cantilever (manufactured by Bruker Corporation, "SCANASYST-AIR", nominal tip radius: 2nm, resonance frequency: 70kHz, spring constant: 0.4N/m) of silicon nitride raw material set in atomic force microscope (manufactured by bruker corporation, apparatus name "Dimension Icon") was used, and press-in and separation were performed at room temperature with a press-in amount of 5nm and a scanning speed of 5 Hz. The surface elastic modulus was calculated by fitting the obtained force curve (horizontal axis represents the deformation of the sample, vertical axis represents the measurement load) to the JKR theoretical formula. The average value of the values obtained by measuring 4096 points in 5 μm×5 μm on the surface of the adhesive layer was used as the surface elastic modulus (MPa).

[ adhesion energy ]

An adhesive tape for semiconductor processing was prepared by exposing one surface of an adhesive layer to an air atmosphere using an ultraviolet irradiation device (manufactured by LINTEC Corporation, device name "RAD 2000") at an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The condition of (2) irradiating ultraviolet rays to the adhesive tape from the substrate side. The surface of the adhesive layer was pressed and separated at room temperature at a press-in amount of 5nm and a scanning speed of 5Hz using a cantilever (manufactured by Bruker corporation, apparatus name "Dimension Icon") of a silicon nitride raw material provided on an atomic force microscope (manufactured by Bruker Corporation, "SCANASYST-AIR", nominal tip radius: 2nm, resonance frequency: 70kHz, spring constant: 0.4N/m). The surface elastic modulus was calculated by fitting the obtained force curve (horizontal axis represents the deformation of the sample, vertical axis represents the measurement load) to the JKR theoretical formula. The average of the values obtained by measuring 4096 points in 5.mu.m.times.5.mu.m of the surface of the adhesive layer was taken as the adhesive energy (J/m) ² )。

The mass parts of the following examples and comparative examples were converted to solid components.

Example 1 >

(1) Substrate material

As a base material, a PET film (TOYOBO CO., LTD. Manufactured by COSMEINE A4300, thickness: 50 μm, young's modulus at 23 ℃ C.: 2550 MPa) with an easy-to-adhere layer on both sides was prepared.

(2) Adhesive layer

(preparation of adhesive composition)

An energy ray curable acrylic resin 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) to obtain an acrylic polymer, and reacting the acrylic polymer with 2-methacryloyloxyethyl isocyanate (MOI) so that 90 mol% of the hydroxyl groups of all the hydroxyl groups of the acrylic polymer are added.

12 parts by mass of a polyfunctional urethane acrylate as an energy ray-curable compound and 1.1 parts by mass of an isocyanate-based crosslinking agent (manufactured by TOSOH CORPORATION, product name

"Coronate L"), 3.3 parts by mass of bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide (manufactured by IGM Resins B.V. Co., ltd., product name "OMNIRADTPO") as a photopolymerization initiator, and diluted with methyl ethyl ketone to prepare a coating liquid of the adhesive composition having a solid content concentration of 32% by mass.

(3) Production of adhesive tape

The coating liquid of the adhesive composition obtained above was applied to the release treated surface of a release sheet (manufactured by LINTECC corporation under the trade name "SP-PET 381031") and dried by heating, whereby an adhesive layer having a thickness of 30 μm was formed on the release sheet. An adhesive tape for semiconductor processing is produced by bonding the surface of the adhesive layer formed with a base material.

Example 2 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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 in the preparation of the adhesive composition.

Example 3 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 4 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 5 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 6 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 60 parts by mass of 2-ethylhexyl acrylate (2 EHA), 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, product name "OMNIRAD 651") was used instead of 3.3 parts by mass of bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide as a photopolymerization initiator in the preparation of the adhesive composition.

Example 7 >

In the preparation of the adhesive composition, an adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 40 parts by mass of 2-ethylhexyl acrylate (2 EHA), 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 8 >

In the preparation of the adhesive composition, an adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 9 >

In the preparation of the adhesive composition, an adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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, and 2.4 parts by mass of 2, 2-dimethoxy-2-phenylacetophenone (manufactured by IGM Resins b.v. company, 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.

Example 10 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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 in the preparation of the adhesive composition.

Comparative example 1 >

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that 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 in the preparation of the adhesive composition.

From the above results, it is found that the adhesive tape for semiconductor processing of the present invention sufficiently reduces the peel strength even in the atmosphere by irradiation with energy rays such as ultraviolet rays. Therefore, by using the adhesive tape of the present invention, even when the thickness of the semiconductor wafer is extremely reduced by back grinding, the occurrence of cracks in the semiconductor chip can be suppressed, and the productivity of the semiconductor device can be improved.

Description of the reference numerals

10: an adhesive tape; 20: a semiconductor wafer; 30: adhesive tape (dicing die-attach tape); 100: the adhesive tape of the present embodiment; 110: a substrate; 120: an adhesive layer.

Claims

1. An adhesive tape for semiconductor processing, which is an adhesive tape having a base material and an adhesive layer, wherein,

exposing one side of the adhesive layer to an atmosphere at an illuminance of 220mW/cm ² The light quantity was 500mJ/cm ² The adhesive tape was irradiated with ultraviolet rays, and a PMMA plate was attached to the exposed surface of the adhesive layer at 23℃and 50% RH with a 2kg roller to and fro, and left for 30 minutes, and then the adhesive tape was peeled at 180℃to have a peel strength of 1600mN/25mm or less.

2. The adhesive tape for semiconductor processing according to claim 1, wherein the adhesive layer comprises an acrylic resin,

3. The adhesive tape for semiconductor processing according to claim 1 or 2, wherein an illuminance is 220mW/cm in a state where one surface of the adhesive layer is exposed to an atmospheric atmosphere ² The light quantity was 500mJ/cm ² The exposed surface of the adhesive layer having a surface free energy of less than 36mJ/m after irradiation of ultraviolet rays to the adhesive tape ² 。

4. A method for manufacturing a semiconductor device includes the steps of:

a step of attaching the adhesive tape for semiconductor processing according to any one of claims 1 to 3 to a surface of a semiconductor wafer, and cutting the adhesive tape along an outer periphery of the semiconductor wafer;

And peeling the adhesive tape from the plurality of chips.

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