CN117099185A - Adhesive tape for semiconductor processing and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention provides a method for preventing the occurrence of chipping in the manufacture of a chip using an adhesive tape for semiconductor processing having a buffer layer. The adhesive tape 10 for semiconductor processing of the present invention is an adhesive tape comprising a base material 11, a buffer layer 13 provided on one surface side of the base material 11, and an adhesive layer 12 provided on the other surface side of the base material 11, wherein a pressing depth (Z) required for a compressive load to reach 2mN is 3.0 μm or less when a tip of a triangular pyramid-shaped indenter having a tip radius of curvature of 100nm and an inter-edge angle of 115 DEG is pressed into the buffer layer at a speed of 10 μm/min for the buffer layer heated to 60 ℃.

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 a semiconductor device is manufactured by a method of forming a groove in a surface of a wafer or forming a modified region in a wafer by laser and singulating the wafer by stress or the like at the time of back grinding of 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 DBG can simultaneously perform back grinding of a wafer and singulation of the wafer, 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 pre-dicing 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 for semiconductor processing 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 or a protective film forming tape for forming a protective film is attached to the grinding surface. Then, the adhesive tape for semiconductor processing attached to the wafer surface is irradiated with energy rays such as ultraviolet rays to reduce the adhesive force, and then peeled off. Through such a step, an adhesive layer or a protective film formation layer is formed on the back surface of the chip.

A laminated adhesive tape including a base material, an adhesive layer, and a buffer layer is sometimes used as an adhesive tape for semiconductor processing. For example, patent document 1 (japanese patent application laid-open No. 2015-183008) discloses a specific example of such an adhesive tape for semiconductor processing. The buffer layer is provided to absorb vibration generated during polishing of the back surface of the wafer or to alleviate the uneven difference due to foreign matter and to stably and flatly hold the wafer.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2015-183008

Disclosure of Invention

Technical problem to be solved by the application

As the miniaturization of semiconductor devices progresses, the final finished thickness of the chip tends to be thin. However, as the thinning of the chip progresses, a phenomenon called "chipping" in which the end portion of the chip is broken increases. The inventors of the present application have conducted intensive studies on the cause and as a result, have obtained the following findings.

In back polishing of a semiconductor wafer, the adhesive tape for semiconductor processing is temporarily adhered to a circuit surface of the wafer and polished while spraying water. Then, a dry polishing step as finishing is sometimes performed. It was found that in this dry polishing process, chips were in contact with each other and frequently caused chipping.

Since the back surface polishing of the semiconductor wafer is performed while spraying water, the temperature of the divided chips does not excessively rise. However, since water cannot be sprayed in the dry polishing process, frictional heat causes a temperature rise of the chip. The thermal wave of the chip and the adhesive tape for semiconductor processing are heated to about 60 ℃ to soften the buffer layer of the adhesive tape. The holding force and the shape retention force of the softened buffer layer are reduced, and the shearing force in the dry polishing process acts to cause the adhesive tape for semiconductor processing to slip and deform. As a result, the divided chips are displaced, and the chips come into contact with each other, so that breakage and chipping of the ends of the chips occur.

In the DBG method, the chip interval (kerf width) is wide, so that the chips are not frequently contacted with each other, but in the LDBG, the kerf width is substantially 0, so that even a slight positional deviation causes the chips to be contacted with each other, and chipping frequently occurs. In particular, chipping is likely to occur in an extremely thin chip whose flexural strength decreases as thinning progresses.

The inventors of the present application have conducted intensive studies to obtain the finding that by preventing positional deviation of a chip at the time of dry polishing, the possibility of chipping can be reduced. In dry polishing, the chip is heated to about 60 ℃ by frictional heat, and the buffer layer of the adhesive tape for semiconductor processing is heated by the heat, resulting in positional deviation of the chip. Accordingly, the inventors of the present application have conceived to reduce chipping by suppressing deformation of the buffer layer upon heating at about 60 ℃. That is, an object of the present application is to suppress occurrence of chipping when manufacturing a chip using an adhesive tape for semiconductor processing having a buffer layer.

Technical means for solving the technical problems

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

(1) An adhesive tape for semiconductor processing, comprising a substrate, a buffer layer provided on one side of the substrate, and an adhesive layer provided on the other side of the substrate, wherein,

The buffer layer heated to 60 ℃ was pressed with a tip of a triangular pyramid-shaped indenter having a tip radius of curvature of 100nm and an inter-edge angle of 115 DEG at a speed of 10 μm/min to a press depth (Z) of 3.0 μm or less required for a compression load of 2 mN.

(2) The adhesive tape for semiconductor processing according to (1), wherein the Young's modulus of the substrate at 23℃is 1000MPa or more.

(3) The adhesive tape for semiconductor processing according to (1) or (2), wherein the buffer layer is a cured product of a composition for forming a buffer layer containing an energy ray-polymerizable compound.

(4) The adhesive tape for semiconductor processing according to any one of (1) to (3), wherein the adhesive tape for semiconductor processing is used so as to be attached to the surface of a semiconductor wafer in a step of polishing the back surface of the semiconductor wafer having a groove formed on the surface of the semiconductor wafer or a modified region formed in the semiconductor wafer and singulating the semiconductor wafer into semiconductor chips by the polishing.

(5) A method of manufacturing a semiconductor device, comprising: attaching the adhesive tape for semiconductor processing according to any one of (1) to (4) 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;

a step of polishing a semiconductor wafer, on the front surface of which the adhesive tape is attached and the grooves or the modified regions are formed, from the 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 step of dry polishing the back surface of the singulated chip; a kind of electronic device with high-pressure air-conditioning system

And peeling the adhesive tape from the plurality of chips.

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

Effects of the invention

The adhesive tape for semiconductor processing of the present invention can suppress occurrence of chipping by suppressing positional deviation of a chip at the time of dry polishing because deformation of a buffer layer at 60 ℃ is suppressed.

Drawings

Fig. 1 is a schematic view showing an adhesive tape for semiconductor processing according to the present embodiment.

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.

The term "semiconductor processing" refers to a process that can be used for carrying a semiconductor wafer, back grinding, dicing, picking up a semiconductor chip, and the like.

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. Dry polishing is a process of mirror-finishing the back surface of a singulated die with a dry grindstone. By this step, the breaking layer on the back surface of the chip is reduced, and the flexural strength is increased.

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

In the present embodiment, as shown in fig. 1, an adhesive tape 10 is a laminate including a base material 11 and an adhesive layer 12. The adhesive tape 10 has a buffer layer 13 on the surface of the substrate 11 opposite to the adhesive layer 12. 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 the 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 constitution of each member of the adhesive tape for semiconductor processing of the present embodiment.

[ substrate 11].

The base material 11 may be any of various resin films conventionally used as a base material of an adhesive tape for semiconductor processing, without particular limitation. From the viewpoint of more reliably holding the wafer and the chip, the Young's modulus of the base material 11 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 vibration and the like at the time of back grinding can be suppressed, whereby chipping and breakage of the semiconductor chip can be prevented. In addition, the stress when the adhesive tape is peeled from the semiconductor chip can be reduced, and chip chipping and breakage caused 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. By setting the thickness of the base material to 110 μm or less, the peeling force of the adhesive tape can be easily controlled. In addition, by setting the thickness of the base material to 15 μm or more, the base material 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 order to improve the adhesion to at least one of the buffer layer and the adhesive layer, at least one surface of the substrate may be subjected to an adhesion treatment such as corona treatment. The base material may have a primer layer formed by coating at least one surface of the resin film with the resin film.

The primer layer-forming composition is not particularly limited, and examples thereof include compositions containing polyester resins, urethane resins, polyester urethane resins, and acrylic resins. The primer layer-forming composition 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 undercoat layer is preferably 0.01 to 10. Mu.m, more preferably 0.03 to 5. Mu.m. In addition, since the thickness of the undercoat layer in the embodiment of the present application is small relative to the thickness of the substrate, the thickness of the resin film having the undercoat layer is substantially the same as the thickness of the substrate. Further, since the material of the primer layer is soft, the young's modulus is less affected, and in the case of having the primer layer, 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.

[ adhesive layer 12]

The pressure-sensitive adhesive layer 12 is not particularly limited as long as it has moderate pressure-sensitive adhesiveness at room temperature, and preferably has a shear storage modulus at 23℃of 0.05 to 0.50MPa. A circuit or the like is generally formed on the surface of a semiconductor wafer and has irregularities. When the shear storage modulus of the adhesive layer is in the above range, the adhesive tape is attached to the wafer surface having the irregularities, whereby the adhesive layer can be brought into sufficient contact with the irregularities of the wafer surface, and the adhesiveness of the adhesive layer can be properly exhibited. Therefore, the adhesive tape can be reliably fixed to the semiconductor wafer, and the wafer surface can be properly protected during back grinding. From these viewpoints, the shear storage modulus of the adhesive layer is more preferably 0.12 to 0.35MPa. The shear storage modulus of the adhesive layer refers to the shear storage modulus before curing by irradiation of energy rays when the adhesive layer is formed of an energy ray-curable adhesive.

The shear storage modulus can be measured by the following method. The adhesive layer having a thickness of about 0.5 to 1mm was die-cut into a round shape having a diameter of 7.9mm, and this was used as a measurement sample. The elastic modulus of the test sample was measured at a frequency of 1Hz using a dynamic viscoelasticity measuring device ARES manufactured by Rheometric Inc. at a temperature change rate of 3 ℃/min in a temperature range of-30℃to 150 ℃. The elastic modulus at a measured temperature of 23℃was taken as the shear storage modulus at 23 ℃.

The thickness of the adhesive layer is preferably less than 100. Mu.m, more preferably 5 to 80. Mu.m, still more preferably 10 to 70. Mu.m. If the adhesive layer is thinned in this way, generation of adhesive tape dust at the time of cutting the adhesive tape is easily suppressed, and cracking of the semiconductor chip at the time of back grinding is easily prevented.

The adhesive layer is formed of, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, or the like, and an acrylic adhesive is preferable.

Further, the adhesive layer is preferably formed of an energy ray curable adhesive. By forming the adhesive layer from an energy ray-curable adhesive, the shear storage modulus at 23 ℃ can be set within the above range before curing by irradiation with energy rays, and the peel force after curing can be easily set to 1000mN/50mm or less.

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

[ adhesive composition ]

As the energy ray-curable adhesive for forming the adhesive layer, for example, an energy ray-curable adhesive composition (hereinafter, also referred to as "X-type adhesive composition") containing an energy ray-curable compound other than an adhesive resin in addition to an adhesive resin that is not energy ray-curable (also referred to as "adhesive resin I") can be used. 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 can 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 other than the energy ray-curable adhesive resin in addition to the energy ray-curable adhesive resin II may be used in combination of the X-type and Y-type.

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.

Acrylic polymers are 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.

The content of the alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group is preferably 40 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 simply referred to as "total amount of the monomers").

The acrylic polymer preferably contains a structural unit derived from an alkyl (meth) acrylate having 1 to 3 carbon atoms in the alkyl group in addition to a structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group in order to adjust the elastic modulus and the adhesive property of the adhesive layer. The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having 1 or 2 carbon atoms, more preferably methyl (meth) acrylate, and most preferably methyl methacrylate. 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 6 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 become a crosslinking origin, or may be reacted with an unsaturated group-containing compound to introduce an unsaturated group into the 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 this embodiment, two or more of the hydroxyl group-containing monomer, carboxyl group-containing monomer, amino group-containing monomer, epoxy group-containing monomer, and the like may be used singly or in combination. Among these functional group-containing monomers, 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 methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; 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 crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and anhydrides thereof; 2-carboxyethyl methacrylate, and the like.

The content of the functional group-containing monomer 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 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 may be used as the non-energy ray-curable adhesive resin I (acrylic resin). The energy ray-curable acrylic resin may be an acrylic polymer obtained by reacting a 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 a 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 glycidyl (meth) 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 groups remain without reacting with the unsaturated group-containing compound, and thus the crosslinking agent is easily used to crosslink the functional groups. 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 a polyvalent (meth) acrylate monomer 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, epoxy (meth) acrylate, and the like.

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 crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate and adducts thereof; epoxy crosslinking agents such as ethylene glycol glycidyl ether; aziridine crosslinking agents such as hexa [1- (2-methyl) -aziridinyl ] triphosphoric acid triazine; 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 with low energy rays such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds; photosensitizers such as amines and quinones; more specifically, for example, 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, 2-dimethoxy-2-phenylacetophenone, and the like are exemplified.

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, and 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 in the synthesis of the adhesive resin, or one or more organic solvents other than the organic solvent used in the synthesis may be added to uniformly coat the adhesive composition.

[ buffer layer 13]

The adhesive tape 10 of the present embodiment has a buffer layer 13. An adhesive layer 12 is provided on one surface of the base material 11, and a buffer layer 13 is provided on the other surface of the base material 11.

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 the adhesive tape is adhered along the outer side Zhou Qieduan of the semiconductor wafer, the semiconductor wafer is placed on a chuck table (chuck table) via the adhesive tape and back-ground, and the semiconductor wafer is easily held on the chuck table by providing the adhesive tape with a buffer layer as a constituent layer. In addition, even if foreign matter exists on the chuck table, the deformation of the buffer layer can absorb the concave-convex of the foreign matter, so that the wafer can be ground into a smooth and uniform thickness.

The adhesive tape of the present embodiment is characterized in that deformation of the buffer layer at high temperature is suppressed. Specifically, when the tip of a triangular pyramid-shaped indenter having a tip radius of curvature of 100nm and an inter-edge angle of 115 DEG is pushed into a buffer layer heated to 60 ℃, the push depth (Z) required for a compression load to reach 2mN is 3.0 μm or less. The press-in depth (Z) is preferably 2.8 μm or less, more preferably 2.6 μm or less. The lower limit of the press-in depth (Z) is not particularly limited, and if the buffer layer is hard to deform and excessively hard, the absorption of the chuck table and the absorption of the irregularities of the foreign matter are incomplete, and therefore the press-in depth (Z) is preferably 0.01 μm or more, and more preferably 0.1 μm or more.

Since the buffer layer is a layer obtained by curing a composition for forming a buffer layer described later, it is relatively easy to adjust the viscoelasticity by selecting the composition of the composition for forming a buffer layer. Further, by providing the buffer layer adjusted so that the press depth (Z) is 3.0 μm or less, deformation of the buffer layer at high temperature is suppressed, and therefore, the adhesive tape 10 is not deformed in the dry polishing process, and chipping can be reduced. On the other hand, in the case of the adhesive tape having the buffer layer with the press depth (Z) of more than 3.0 μm, the adhesive tape is easily deformed in the dry polishing process, and the chip ends are easily broken by contact with each other.

In the present embodiment, the press depth (Z) is a value measured by the method described in the example. The press depth (Z) can be adjusted to fall within the above range by appropriately changing the kind and content of the components contained in the composition for forming a buffer layer, the curing degree of the buffer layer, and the like.

The buffer layer is a layer softer than 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 grinding.

The composition of the buffer layer is not limited as long as the press depth (Z) is satisfied, but a cured product of the composition for forming the buffer layer containing an energy ray-polymerizable compound is preferable from the viewpoint of easy control of viscoelasticity.

The components contained in the layer formed from the composition for forming a buffer layer containing an energy ray-polymerizable compound 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.

Further, the composition for forming a buffer layer containing an energy ray-polymerizable compound more specifically preferably contains a urethane (meth) acrylate (a 1). The composition for forming a buffer layer preferably contains, in addition to the above (a 1), 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. 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 further 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 "the number of functional groups") 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 ' -diisocyanate-dimethylcyclohexane; 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 and 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, morpholine (meth) acrylate, and cyclotrimethylolpropane methylacrylate.

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.

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 30 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 a proper 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 and methyl glycidyl (meth) acrylate 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.

The content of the component (a 3) in the composition for forming a buffer layer is preferably 0 to 40 parts by mass, more preferably 0 to 35 parts by mass, and even more preferably 0 to 30 parts by mass, relative to the total amount (100 parts by mass) of the composition for forming a buffer layer.

(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 reacts with the (meth) acryloyl group in the component (a 1) or the photopolymerizable unsaturated group in the component (a 4) reacts 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 ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate having a repeating unit derived from a diol of 200 to 800, 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 polyethylene glycol di (meth) acrylate, the number of glycol units is generally indicated in brackets, for example, when the number of glycol units is 600, polyethylene glycol (600) diacrylate is indicated.

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

Among them, polyethylene glycol diacrylate and neopentyl glycol di (meth) acrylate are 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.

(component (a 1) to component (a 4) other than the polymerizable compound (a 5))

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, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone and N-vinylcaprolactam. In addition, the component (a 5) may be used singly 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, and peroxide compounds; examples of the photosensitizers include amine and quinone; more specifically, for example, 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 are exemplified.

These photopolymerization initiators may 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 further 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, dyes, and the like. 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 further contain a resin component within a range that does not impair the effects of the present invention. Examples of the resin component include polyolefin resins such as a polyene-thiol resin, polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as a styrene copolymer.

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). In addition, the buffer layer preferably contains polymerized units derived from component (a 2) and/or polymerized units derived from component (a 3). Further, the polymer may contain a polymer unit derived from the component (a 4) and/or a polymer unit derived from the component (a 5). 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).

(control of the pressing depth (Z) of the buffer layer)

The buffer layer is obtained by curing the above-mentioned buffer layer-forming composition. The viscoelastic properties of the buffer layer can be adjusted by selecting the composition of the buffer layer-forming composition. Therefore, in order to control the press-in depth (Z) of the buffer layer within the above range, the types and contents of the above components constituting the composition for forming the buffer layer may be adjusted. The guidelines for adjusting the types and contents of the respective components are described below.

For example, if the number of (meth) acryl groups of the urethane (meth) acrylate (a 1) is large, the crosslinked structure in the buffer layer increases, and the press-in depth (Z) decreases.

The depth of press-fitting can be adjusted by using the type and content of the urethane (meth) acrylate (a 1), the polymerizable compound (a 2) having an alicyclic group or heterocyclic group having 6 to 20 ring-forming atoms, the polymerizable compound (a 3) having a functional group, and the polyfunctional polymerizable compound (a 4).

If the buffer layer contains a large number of crosslinked structures, the buffer layer becomes hard and the indentation depth (Z) tends to decrease. Accordingly, the indentation depth (Z) can be controlled within an appropriate range by adjusting the content of the component involved in the formation of the crosslinked structure. Examples of the component involved in forming the crosslinked structure include a (meth) acryl group of the urethane (meth) acrylate (a 1) and a polyfunctional polymerizable compound (a 4). In particular, the polyfunctional polymerizable compound (a 4) is easy to use and is a useful component for forming a crosslinked structure.

In addition, if the buffer layer includes softer structural units (for example, units having a longer chain length), the indentation depth (Z) tends to increase. Accordingly, the indentation depth (Z) can be controlled within an appropriate range by adjusting the content of the component involved in forming the long chain structure. The long chain unit includes a urethane chain of the urethane (meth) acrylate (a 1) and the like.

The buffer layer may further contain additives such as 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 buffer layer may be transparent or opaque, and may be colored or vapor deposited as needed.

[ Release sheet ]

The surface of the adhesive tape may be attached with a release sheet. 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 for removal 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 resins, alkyd resins, fluorine resins, and the like.

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, a 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 bonded to a substrate and removed, whereby a laminate of the buffer layer and the substrate can be obtained.

The pressure-sensitive adhesive layer provided on the release sheet is bonded to the base material side of the laminate, and the pressure-sensitive adhesive tape having the release sheet attached to the surface of the pressure-sensitive adhesive layer can be produced. The release sheet attached to the surface of the adhesive layer can be suitably peeled off and removed before the adhesive tape is used.

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

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

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

Examples of the method for applying the composition for forming a buffer layer include spin coating, spray coating, bar coating, doctor blade coating, roll coating, blade coating, die coating, and gravure coating. In order to improve the coatability, the buffer layer-forming composition may be coated on the 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 curing a coating film of the composition for forming a buffer layer by irradiation with energy rays. 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 the 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 to coat the coating film with a release sheet, a base material, or the like and to cure the coating film by irradiation with energy rays in a state where the coating film is not exposed.

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 an adhesive layer may be formed on the buffer layer side on 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, the "chip set" refers to a plurality of semiconductor chips held on the adhesive tape of the present invention in a regular arrangement 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 5.

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

and 4, step 4: a step of dry polishing the back surface of the singulated chip;

and step 5: and a step of peeling the adhesive tape from the singulated semiconductor wafer (i.e., the plurality of semiconductor chips).

Hereinafter, each step of the method for manufacturing a semiconductor device will be described in detail.

(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 the 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.

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. By using laser to set modified region inside wafer The thickness of the singulated semiconductor chips can be easily made to be 50 μm or less, and more preferably 10 to 45 μm by singulating the wafers using the LDBG of the wafer with stress or the like at the time of back grinding. 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 。

(Process 4)

After the back surface grinding is finished, dry polishing is performed before the chip is picked up. Dry polishing is a process of mirror-finishing the back surface of a singulated die with a dry grindstone. Through the process, the breaking layer on the back of the chip is reduced, and the flexural strength is improved.

In dry polishing, the chip is heated to about 60 ℃ by frictional heat. Due to this heat, the buffer layer of the adhesive tape for semiconductor processing is heated and easily deformed. However, in the buffer layer of the adhesive tape for semiconductor processing of the present invention, as described above, the press-in depth (Z) at 60 ℃ is controlled to be within a certain range, so that deformation of the buffer layer can be suppressed and chipping can be reduced.

(Process 5)

Next, the adhesive for semiconductor processing is peeled from the singulated semiconductor wafer (i.e., the plurality of semiconductor chips aligned 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 surface 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 bonded 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.

When an adhesive tape is used or a film-like adhesive is attached to the back surface 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. In addition, a protective film forming tape for forming a protective film on the back surface of the chip may be used instead of the adhesive tape.

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.

[ measurement of pressing depth (Z) ]

The measurement was performed using a dynamic ultra-microhardness tester (manufactured by SHIMADZU CORPORATION Co., ltd., product name "DUH-W201S") and a triangular pyramid-shaped indenter having a tip curvature radius of 100nm and an inter-edge angle of 115℃as indenters, in an environment of 23℃and 50% RH (relative humidity). Specifically, the release sheet on the buffer layer of the adhesive tape thus produced was removed, and the release sheet was placed on a glass plate of a dynamic ultra-microhardness tester heated to 60℃so as to expose the buffer layer, and after the release sheet was allowed to stand for 60 seconds, the tip of the triangular pyramid-shaped indenter was pushed into the buffer layer at a rate of 10 μm/min, and the push depth (Z) at which the compression load reached 2mN was measured.

[ crack evaluation ]

The semiconductor processing adhesive tapes produced in examples and comparative examples were attached to silicon wafers having a diameter of 12 inches and a thickness of 775 μm using a tape bonder for back grinding (manufactured by LINTEC Corporation, apparatus name "RAD 3510F/12"). A lattice-shaped modified region was formed on the wafer using a laser cutter (manufactured by DISCO Corporation under the device name "DFL 7361"). The size of the lattice was 10mm×10mm.

Then, the back surface polishing device (DISCO Corporation, device name

"DGP 8761"), grinding (including dry polishing) to a thickness of 30 μm, and singulating the wafer into a plurality of chips. After the polishing step, the dicing tape (manufactured by LINTEC Corporation, adwill D-175D) is attached to the surface opposite to the surface to which the adhesive tape for semiconductor processing is attached, and then the adhesive tape for semiconductor processing is peeled off. The singulated chips were then observed with a digital microscope, the chips having cracks were counted, and the size of each crack was classified according to the following criteria. In addition, the crack length (μm) in the longitudinal direction of the chip was compared with the crack length (μm) in the transverse direction of the chip, and the larger one was designated as the size (μm) of the crack.

(Standard)

Large cracks: the size of the crack is more than 20 mu m

Medium crack: the crack size is 10 μm or more and 20 μm or less

Small cracks: the size of the crack is less than 10 mu m

Further, the crack generation rate (%) was calculated according to the following formula. The case where the crack generation rate was 2.0% or less, the number of large cracks was 0, the number of medium cracks was 10 or less, and the number of small cracks was 20 or less was evaluated as "a", and the other cases were evaluated as "F".

Crack generation rate (%) =number of chips with crack generation/total number of chips×100

The mass parts of the following examples and comparative examples are each in terms of solid content.

Example 1 ]

(1) Substrate material

As a base material, a double-coated PET film (TOYOBO CO., LTD. Manufactured under the product name "COSMEINE A4300", thickness: 50 μm, young's modulus at 23 ℃ C.: 2550 MPa) was prepared.

(2) Adhesive layer

(preparation of adhesive composition)

100 parts by mass of an acrylic copolymer (BA/MMA/2 hea=52/20/28 (mass%) having structural units derived from n-Butyl Acrylate (BA), methyl Methacrylate (MMA) and 2-hydroxyethyl acrylate (2 HEA), 6 parts by mass of a multifunctional urethane acrylate ultraviolet curable resin, 1 part by mass of a diisocyanate curing agent, and 1 part by mass of bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide as a photopolymerization initiator were blended, and diluted with methyl ethyl ketone to prepare a solution of an adhesive having a solid content concentration of 32 mass%. Then, a release sheet (manufactured by LINTEC Corporation under the trade name "SP-PET381031", silicone release-treated polyethylene terephthalate (PET) film, thickness: 38 μm) was coated with the solution of the adhesive composition on the release-treated surface, and the release sheet was dried to prepare an adhesive layer-attached release sheet having an adhesive layer with a thickness of 20 μm.

(3) Buffer layer

(preparation of composition for Forming buffer layer)

A urethane acrylate oligomer (CN 8888), isobornyl acrylate (IBXA), cyclic trimethylolpropane methylacrylate, neopentyl glycol diacrylate, polyethylene glycol (600) diacrylate, which were obtained from the company Serdoma, were blended as an energy ray polymerizable compound in the amounts shown in Table 1, and 2.0 parts by mass of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by BASF, product name "Omnirad 1173") as a photopolymerization initiator was further blended to prepare a composition for forming a buffer layer.

The composition for forming a buffer layer was applied to a release sheet (manufactured by LINTEC Corporation under the trade name "SP-PET381031", a silicone release-treated polyethylene terephthalate (PET) film, and a thickness of 38 μm) on the release-treated surface to form a coating film. Then, the coating film was irradiated with ultraviolet light to semi-cure the coating film, thereby forming a semi-cured film having a buffer layer with a thickness of 28. Mu.m.

The ultraviolet irradiation was performed by using a conveyor type ultraviolet irradiation apparatus (product name

"ECS-401GX", EYE GRAPHICS Co., ltd., manufacturing) and a high-pressure mercury lamp (product name

"H04-L41", EYE GRAPHICS Co., ltd.) at a lamp height of 260mm, an output power of 80W/cm, and an illuminance of 70mW/cm ² The irradiation amount was 30mW/cm ² Is carried out under irradiation conditions of (2). Then, the surface of the formed semi-cured film was bonded to the first coating layer of the base material, and ultraviolet light was again irradiated from the release sheet side on the semi-cured film, so that the semi-cured film was completely cured, thereby forming a buffer layer having a thickness of 28. Mu.m.

(4) Production of adhesive tape

Next, the adhesive layer of the release sheet with an adhesive layer was bonded to the second coating layer of the PET film with both surfaces coated, to prepare an adhesive tape for semiconductor processing. The indentation depth (Z) of the buffer layer was measured using an adhesive tape for semiconductor processing, and crack evaluation was performed. The results are shown in table 1.

< examples 2 to 4, comparative examples 1 and 2>

An adhesive tape for semiconductor processing was produced in the same manner as in example 1, except that the buffer layer-forming composition was changed as shown in table 1. The results are shown in Table 1.

TABLE 1

From the above results, it is clear that the adhesive tape for semiconductor processing according to the present invention suppresses the deformation of the buffer layer at 60 ℃.

Description of the reference numerals

10: an adhesive tape; 11: a substrate; 12: an adhesive layer; 13: and a buffer layer.

Claims (6)

1. An adhesive tape for semiconductor processing, comprising a substrate, a buffer layer provided on one side of the substrate, and an adhesive layer provided on the other side of the substrate, wherein,

the buffer layer heated to 60 ℃ was pressed with a tip of a triangular pyramid-shaped indenter having a tip radius of curvature of 100nm and an inter-edge angle of 115 DEG at a speed of 10 μm/min to a press depth (Z) of 3.0 μm or less required for a compression load of 2 mN.

2. The adhesive tape for semiconductor processing according to claim 1, wherein the Young's modulus of the base material at 23℃is 1000MPa or more.

3. The adhesive tape for semiconductor processing according to claim 1 or 2, wherein the buffer layer is a cured product of a composition for forming a buffer layer containing an energy ray-polymerizable compound.

4. The adhesive tape for semiconductor processing according to any one of claims 1 to 3, wherein the adhesive tape for semiconductor processing is used so as to be attached to a surface of a semiconductor wafer in a step of polishing a back surface of the semiconductor wafer having a groove formed on the surface of the semiconductor wafer or a modified region formed in the semiconductor wafer and singulating the semiconductor wafer into semiconductor chips by the polishing.

5. A method of manufacturing a semiconductor device, comprising:

a step of attaching the adhesive tape for semiconductor processing according to any one of claims 1 to 4 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;

a step of polishing a semiconductor wafer, on the front surface of which the adhesive tape is attached and the grooves or the modified regions are formed, from the 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 step of dry polishing the back surface of the singulated chip; a kind of electronic device with high-pressure air-conditioning system

And peeling the adhesive tape from the plurality of chips.

6. The method for manufacturing a semiconductor device according to claim 5, further comprising a step of attaching dicing die attach tape to a back surface of the semiconductor chip.