JP2022009012A - Adhesive tape for semiconductor processing and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent chipping of a semiconductor chip which occurs when a semiconductor wafer is ground and individualized into chips and when an adhesive tape is peeled from the semiconductor chip, in a pre-dicing method.

SOLUTION: An adhesive tape for semiconductor processing in the present invention is used while being stuck on a front face of a semiconductor wafer in the step of grinding a rear face of the semiconductor wafer in which a groove is formed or a modified region is formed on the front face of the semiconductor wafer, and individualizing the semiconductor wafer into semiconductor chips through the grinding. The adhesive tape for semiconductor processing comprises a substrate, a buffer layer which is provided on one face of the substrate, and an adhesive layer which is provided on the other face of the substrate. A total tape thickness of the adhesive tape for semiconductor processing is equal to or less than 160 μm. A ratio (D2/D1) of a thickness (D2) of the buffer layer with respect to a thickness (D1) of the substrate is equal to or less than 0.7, and a peel force with respect to the semiconductor wafer is equal to or less than 1000 mN/50 mm.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an adhesive tape for semiconductor processing used by being attached to a semiconductor wafer when manufacturing a semiconductor device by a pre-dicing method, and a method for manufacturing a semiconductor device using the adhesive tape.

As various electronic devices become smaller and more multifunctional, the semiconductor chips mounted on them are also required to be smaller and thinner. In order to reduce the thickness of the chip, it is common to grind the back surface of the semiconductor wafer to adjust the thickness. Further, a method called a pre-dicing method may be used in which a groove having a predetermined depth is formed from the front surface side of the wafer, grinding is performed from the back surface side of the wafer, and the chips are separated into individual pieces by the grinding. In the pre-dicing method, the back surface of the wafer can be ground and the chips can be separated into individual pieces at the same time, so that a thin chip can be efficiently manufactured. Further, in the pre-dicing method, as described above, in addition to the method of forming a groove having a predetermined depth from the front surface side of the wafer and then grinding from the back surface side of the wafer, a modified layer is provided inside the wafer with a laser to provide a wafer. There is also a method of individualizing the chip by the pressure at the time of backside grinding.

Conventionally, when grinding the back surface of a semiconductor wafer, an adhesive tape called a back grind sheet is attached to the surface of the wafer in order to protect the circuit on the surface of the wafer and to fix the semiconductor wafer and the fragmented semiconductor chip. Is common. The backgrinding sheet used in the pre-dicing method is a pressure-sensitive adhesive sheet provided with a base material and an adhesive layer provided on one surface of the base material, and a cushioning layer is further provided on the other surface side of the base material. It has been known.
By providing the back grind sheet with a cushioning layer, it is possible to alleviate the vibration generated when grinding the back surface of the wafer. Further, the semiconductor wafer is fixed to the table by adsorbing the wafer surface side provided with the back grind sheet to the chuck table at the time of backside grinding, but the cushioning layer causes unevenness due to foreign matter existing on the table. It is also possible to absorb. The back grind sheet prevents cracking of the semiconductor wafer and chipping of chips that occur during backside grinding due to the action of the above buffer layer.

Further, in Patent Document 1, in the pressure-sensitive adhesive sheet having the above-mentioned base material, pressure-sensitive adhesive layer, and cushioning layer, the thickness of the base material is 10 to 150 μm, and the Young's modulus is 1000 to 30,000 MPa. A pressure-sensitive adhesive sheet having a cushioning layer having a thickness of 5 to 80 μm and having a maximum value of tan δ of its dynamic viscoelasticity of 0.5 or more is disclosed. Patent Document 1 discloses that by using this adhesive sheet as a backgrinding sheet, chipping and discoloration of the chip can be prevented when a semiconductor chip is manufactured by the pre-dicing method.

Japanese Unexamined Patent Publication No. 2005-343997

However, in recent years, the demand for thinner and smaller semiconductor chips has been further increasing, and for example, it has become necessary to manufacture semiconductor chips having a thickness of less than 50 μm or a semiconductor chip having a thickness of about 0.5 mm square. There is. When manufacturing such a miniaturized and thinned semiconductor chip, as described in Patent Document 1, the Young's modulus of the base material and the maximum value of tan δ of the buffer layer are adjusted, and the base material and the buffer are buffered. It may be difficult to suppress breakage (chip cracks) such as chipping and cracking of semiconductor chips only by setting the thickness of each layer within a certain range. In particular, it has been found that when the surface protective tape is peeled off from the surface of the wafer after grinding, a large load is applied to the above-mentioned miniaturized and thinned semiconductor chips, which causes chip breakage.

The present invention has been made in view of the above problems, and even in the case of manufacturing a thin and miniaturized semiconductor chip by the dicing method, the semiconductor chip is chipped or damaged. It is an object of the present invention to provide an adhesive tape for semiconductor processing capable of preventing the above.

As a result of considering the mechanism by which the semiconductor chip is chipped or damaged, the present inventors have found that when manufacturing a semiconductor chip that is thinner and smaller by the pre-dicing method, when grinding the back surface of the semiconductor wafer, and , It was found that the semiconductor chip was chipped or damaged when the adhesive tape was peeled off from the semiconductor chip. Then, in the pre-dicing method, in order to prevent the semiconductor chip from being chipped or damaged when the semiconductor wafer is ground and separated into chips and when the adhesive tape is peeled off from the semiconductor chip, the adhesive tape is taped. We found that it is important to keep the peeling force of the adhesive tape on the semiconductor wafer to a predetermined value or less while setting the total thickness and the thickness ratio between the base material and the buffer layer within a certain range, and completed the following invention. I let you.

The present invention provides the following (1) to (13).
(1) In a process of grinding the back surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer or having a modified region formed on the semiconductor wafer, and the grinding to individualize the semiconductor wafer into semiconductor chips, the semiconductor wafer It is an adhesive tape for semiconductor processing that is used by being attached to the surface of
A base material, a cushioning layer provided on one surface of the base material, and an adhesive layer provided on the other side of the base material are provided.
The total thickness of the adhesive tape for semiconductor processing is 160 μm or less, and the ratio (D2 / D1) of the thickness of the buffer layer (D2) to the thickness of the base material (D1) is 0.7 or less. Adhesive tape for semiconductor processing with a peeling force of 1000 mN / 50 mm or less for semiconductor wafers.
(2) The adhesive tape for semiconductor processing according to (1) above, wherein the Young's modulus of the base material is 1000 MPa or more.
(3) The adhesive tape for semiconductor processing according to (1) or (2) above, wherein the thickness (D1) of the base material is 110 μm or less.
(4) The adhesive tape for semiconductor processing according to any one of (1) to (3) above, wherein the base material has at least a polyethylene terephthalate film.
(5) The pressure-sensitive adhesive tape for semiconductor processing according to any one of (1) to (4) above, wherein the pressure-sensitive adhesive layer is formed of an energy ray-curable pressure-sensitive adhesive.
(6) The pressure-sensitive adhesive tape for semiconductor processing according to any one of (1) to (5) above, wherein the elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. is 0.10 to 0.50 MPa.
(7) The pressure-sensitive adhesive tape for semiconductor processing according to any one of (1) to (6) above, wherein the thickness (D3) of the pressure-sensitive adhesive layer is 70 μm or less.
(8) The adhesive layer is a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms and a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms. The pressure-sensitive adhesive tape for semiconductor processing according to any one of (1) to (7) above, which is formed from a pressure-sensitive adhesive composition containing an acrylic resin having a structural unit derived from a functional group-containing monomer.
(9) The adhesive tape for semiconductor processing according to any one of (1) to (8) above, wherein the cushioning layer has a storage elastic modulus of 100 to 1500 MPa at 23 ° C.
(10) The adhesive tape for semiconductor processing according to any one of (1) to (9) above, wherein the stress relaxation rate of the buffer layer is 70 to 100%.
(11) The buffer layer is a urethane (meth) acrylate (a1), a polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms, and a polymerizable compound having a functional group (11). The adhesive tape for semiconductor processing according to any one of (1) to (10) above, which is formed from the composition for forming a buffer layer containing a3).
(12) The adhesive tape for semiconductor processing according to (11) above, wherein the component (a2) is an alicyclic group-containing (meth) acrylate and the component (a3) is a hydroxyl group-containing (meth) acrylate.
(13) A step of attaching the adhesive tape for semiconductor processing according to any one of (1) to (12) above to the surface of a semiconductor wafer.
A process of forming a groove from the front surface side of the semiconductor wafer or forming a modified region inside the semiconductor wafer from the front surface or the back surface of the semiconductor wafer.
A semiconductor wafer having the adhesive tape for semiconductor processing affixed to the front surface and having the groove or the modified region formed thereof is ground from the back surface side, and the groove or the modified region is used as a starting point to form individual pieces on a plurality of chips. And the process of making it
The process of peeling the adhesive tape for semiconductor processing from the plurality of chips,
A method for manufacturing a semiconductor device.

In the present invention, in the pre-dicing method, it is possible to prevent chipping or breakage of the semiconductor chip that occurs when the semiconductor wafer is ground into pieces into chips and when the adhesive tape is peeled off from the semiconductor chip. ..

Next, the present invention will be described in more detail.
In the present specification, "weight average molecular weight (Mw)" is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, and specifically, based on the method described in Examples. It is a measured value.
Further, for example, "(meth) acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.

The adhesive tape for semiconductor processing of the present invention (hereinafter, also simply referred to as "adhesive tape") has a base material, a buffer layer provided on one surface of the base material, and the other surface of the base material (that is, a buffer layer). It is provided with an adhesive layer provided on a surface opposite to the provided surface).
The adhesive tape is used by being attached to the surface of a semiconductor wafer via an adhesive layer in a pre-dicing method. That is, as will be described later, the adhesive tape grinds the back surface of the semiconductor wafer having grooves formed on the surface of the semiconductor wafer or modified regions formed on the semiconductor wafer, and the semiconductor wafer is turned into a semiconductor chip by the grinding. It is used by being attached to the surface of a semiconductor wafer in the process of individualizing.

In the adhesive tape of the present invention, the total thickness of the adhesive tape is 160 μm or less, and the ratio (D2 / D1) of the thickness of the buffer layer (D2) to the thickness of the base material (D1) is 0.7 or less. At the same time, the peeling force of the adhesive tape with respect to the semiconductor wafer is 1000 mN / 50 mm or less. In the present invention, by setting all of the total tape thickness, the thickness ratio (D2 / D1), and the peeling force to predetermined values in this way, when the semiconductor wafer is ground and separated into chips, and It is possible to prevent the semiconductor chip from being chipped or damaged when the adhesive tape is peeled off from the semiconductor chip.

On the other hand, if the total thickness of the adhesive tape is larger than 160 μm, it becomes difficult to reduce the peeling force while appropriately maintaining the adhesive performance of the adhesive layer and the impact absorption performance of the cushioning layer. Therefore, when the adhesive tape is peeled off from the semiconductor chip, a load is applied to the semiconductor chip, and the chip is likely to be chipped.
Further, the total thickness of the tape is preferably 155 μm or less, more preferably 145 μm or less, from the viewpoint of lowering the peeling force. Further, the total thickness of the tape is preferably 40 μm or more, more preferably 55 μm or more, in order to make the pressure-sensitive adhesive layer, the base material, and the buffer layer an appropriate thickness and appropriately exert their respective functions.
In the present specification, the total thickness of the tape means the total thickness of the layers contained in the adhesive tape when the tape is attached to the semiconductor wafer and the semiconductor wafer is ground. Therefore, when the adhesive tape is provided with a peelable sheet that can be peeled off, the thickness of the peelable sheet is not included in the total thickness. Usually, the total thickness of the adhesive tape is the total thickness of the base material, the pressure-sensitive adhesive layer, and the cushioning layer.

Further, when the thickness ratio (D2 / D1) is larger than 0.7, the proportion of the highly rigid portion in the adhesive tape is small, so that the semiconductor wafer or the semiconductor chip is difficult to be properly held by the base material. , Vibration during grinding is less likely to be reduced. Therefore, in the case of individualizing into a small and thin semiconductor chip by the pre-dicing method, even if an appropriate material for the buffer layer is selected, the semiconductor chip generated when the semiconductor chip is individualized by backside grinding. It becomes difficult to prevent chipping.
The thickness ratio (D2 / D1) is preferably 0.10 to 0.70 in order to reduce chip chipping and to improve the cushioning performance of the adhesive tape by setting the cushioning layer to an appropriate thickness. It is more preferably 0.13 to 0.66.

Further, when the peeling force of the adhesive tape on the semiconductor wafer is larger than 1000 mN / 50 mm, the semiconductor chip is likely to be chipped when the adhesive tape is peeled from the semiconductor chip.
Here, in order to more appropriately prevent chipping when the adhesive tape is peeled off, the peeling force of the adhesive tape is preferably 970 mN / 50 mm or less, and more preferably 850 mN / 50 mm or less. The peeling force of the adhesive tape is not particularly limited, but is preferably 300 mN / 50 mm or more, preferably 450 mN / 50 mm or more in order to improve the adhesiveness of the adhesive tape to the semiconductor wafer or semiconductor chip. More preferred.
The peeling force of the adhesive tape is a force required for peeling the adhesive tape from the semiconductor wafer after the surface of the adhesive layer of the adhesive tape is attached to the semiconductor wafer, as shown in Examples described later. However, as will be described later, when the pressure-sensitive adhesive layer is formed of an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive tape attached to the semiconductor wafer is irradiated with energy rays to cure the pressure-sensitive adhesive layer, and then the peeling is measured. It is power. On the other hand, when the pressure-sensitive adhesive layer is formed of a non-energy ray-curable pressure-sensitive adhesive, the peeling force is similarly measured with respect to the pressure-sensitive adhesive tape before irradiation with energy rays.

Next, the configuration of each member of the adhesive tape of the present invention will be described in more detail.
[Base material]
Examples of the base material of the adhesive tape include various resin films, and specifically, polyethylene such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE), polypropylene, and polybutene. , Polybutadiene, polymethylpentene, ethylene-norbornene copolymer, polyolefins such as norbornene resin; ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer Ethylene-based copolymers such as; polyvinyl chloride, polyvinyl chloride such as vinyl chloride copolymer; polyethylenes such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and all aromatic polyesters; polyurethanes, polyimides, polyamides, polycarbonates, etc. Examples thereof include a resin film made of one or more selected from a fluororesin, a polyacetal, a modified polyphenylene oxide, a polyphenylene sulfide, a polysulfone, a polyether ketone, an acrylic polymer and the like. Further, modified films such as these crosslinked films and ionomer films are also used. The base material may be a single-layer film of a resin film made of one or more kinds of resins selected from these resins, or may be a laminated film in which two or more kinds of these resin films are laminated.

The substrate is preferably a rigid substrate having a Young's modulus of 1000 MPa or more, more preferably 1800 to 30,000 MPa, and even more preferably 2500 to 6000 MPa.
In this way, when a rigid substrate with a high Young's modulus is used as the substrate, even if the total thickness of the tape is reduced as described above, the holding performance of the adhesive tape on the semiconductor wafer or semiconductor chip is improved, and vibration during backside grinding is improved. By suppressing such factors, it becomes easier to prevent the semiconductor chip from being chipped or damaged. Further, when the Young's modulus is in the above range, the stress when the adhesive tape is peeled from the semiconductor chip can be reduced, and it becomes easy to prevent the chip from being chipped or broken when the tape is peeled. Further, it is possible to improve the workability when the adhesive tape is attached to the semiconductor wafer.

Here, the rigid substrate having a young ratio of 1000 MPa or more may be appropriately selected from the above-mentioned resin films, but polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and all aromatic polyesters, polyimides, etc. Examples thereof include films such as polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and biaxially stretched polypropylene.
Among these resin films, a film containing at least one selected from a polyester film, a polyamide film, a polyimide film, and a biaxially stretched polypropylene film is preferable, a polyester film is more preferable, and a polyethylene terephthalate film is further preferable. ..

The thickness (D1) of the base material is preferably 110 μm or less, more preferably 15 to 110 μm, and even more preferably 20 to 105 μm. By setting the thickness of the base material to 110 μm or less, it becomes easy to adjust the total tape thickness of the adhesive tape, the thickness ratio (D2 / D1), and the peeling force of the adhesive tape to the above-mentioned predetermined values. Further, when the thickness is 15 μm or more, the base material can easily function as a support for the adhesive tape.

Further, the substrate may contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc., as long as the effects of the present invention are not impaired. good. Further, the base material may be transparent or opaque, and may be colored or vapor-deposited as desired.
Further, the surface of at least one of the base materials may be subjected to an adhesive treatment such as a corona treatment in order to improve the adhesion to at least one of the buffer layer and the pressure-sensitive adhesive layer. Further, the base material may have the above-mentioned resin film and an easily adhesive layer coated on at least one surface of the resin film.

The composition for forming the easy-adhesive layer for forming the easy-adhesive layer is not particularly limited, and examples thereof include compositions containing a polyester resin, a urethane resin, a polyester urethane resin, an acrylic resin, and the like. The composition for forming an easy-adhesion layer may contain a cross-linking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust preventive, a pigment, a dye and the like, if necessary. good.
The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm. Since the thickness of the easy-adhesive layer is small with respect to the thickness of the base material and the material is soft, the influence on the Young's modulus is small, and the Young's modulus of the base material is the resin film even when the easy-adhesive layer is provided. It is substantially the same as the Young's modulus of.

[Cushioning layer]
The cushioning layer alleviates the vibration caused by grinding the semiconductor wafer and prevents the semiconductor wafer from cracking and chipping. Further, the semiconductor wafer to which the adhesive tape is attached is placed on the vacuum table at the time of backside grinding, but the adhesive tape is easily held on the vacuum table by providing the cushioning layer.
The cushioning layer of the present invention preferably has a storage elastic modulus at 23 ° C. of 100 to 1500 MPa, more preferably 200 to 1200 MPa. The stress relaxation rate of the buffer layer is preferably 70 to 100%, more preferably 78 to 98%.
Since the cushioning layer has a storage elastic modulus and stress relaxation rate within the above ranges, the unevenness of fine foreign matter sandwiched between the semiconductor wafer to which the adhesive tape is attached and the chuck table, and the unevenness of the grindstone generated during backside grinding. The effect of the cushioning layer to absorb vibrations and shocks is enhanced. Therefore, as described above, even when the thickness ratio (D2 / D1) is 0.7 or less and the thickness of the cushioning layer is thin, it is easy to prevent chip chipping that occurs during backside grinding.

The maximum value of tan δ of dynamic viscoelasticity at −5 to 120 ° C. of the buffer layer (hereinafter, also simply referred to as “maximum value of tan δ”) is preferably 0.7 or more, more preferably 0.8 or more, still more preferable. Is 1.0 or more. The upper limit of the maximum value of tan δ is not particularly limited, but is usually 2.0 or less.
When the maximum value of tan δ of the cushioning layer is 0.7 or more, the effect of absorbing the vibration and impact of the grindstone generated during backside grinding becomes high. Therefore, in the pre-dicing method, even if the semiconductor wafer or the fragmented semiconductor chip is ground until it becomes extremely thin, it becomes easy to prevent chipping at the corners of the chip or the like.
In addition, tan δ is called loss tangent, and is defined by “loss elastic modulus / storage elastic modulus”, and is a value measured by the response to stress such as tensile stress and torsional stress applied to the object by a dynamic viscoelastic modulus measuring device. Specifically, it means a value measured by the method described in the examples.

The thickness (D2) of the buffer layer is preferably 8 to 40 μm, more preferably 10 to 35 μm. By setting the thickness of the cushioning layer to 8 μm or more, the cushioning layer can appropriately cushion the vibration during backside grinding. Further, when it is 40 μm or less, it becomes easy to adjust the total tape thickness and the thickness ratio (D2 / D1) to the above-mentioned predetermined values.

The buffer layer is preferably a layer formed from a composition for forming a buffer layer containing an energy ray-polymerizable compound. By containing the energy ray-polymerizable compound, the buffer layer can be cured by being irradiated with energy rays. The "energy ray" refers to ultraviolet rays, electron beams, etc., and preferably ultraviolet rays are used.
Further, more specifically, the composition for forming a buffer layer contains urethane (meth) acrylate (a1) and a polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms. Is preferable. By containing these two components, the composition for forming a buffer layer can easily keep the elastic modulus of the buffer layer, the stress relaxation rate of the buffer layer, and the maximum value of tan δ within the above ranges. From these viewpoints, it is more preferable that the composition for forming a buffer layer contains a polymerizable compound (a3) having a functional group in addition to the above components (a1) and (a2).
Further, it is more preferable that the composition for forming a buffer layer contains a photopolymerization initiator in addition to the above components (a1) and (a2) or (a1) to (a3), and the effect of the present invention is not impaired. In the range, other additives and resin components may be contained.
Hereinafter, each component contained in the composition for forming a buffer layer will be described in detail.

(Urethane (meth) acrylate (a1))
The urethane (meth) acrylate (a1) is a compound having at least a (meth) acryloyl group and a urethane bond, and has a property of being polymerized and cured by energy ray irradiation. Urethane (meth) acrylate (a1) is a polymer such as an oligomer.

The mass average molecular weight (Mw) of the component (a1) is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, still more preferably 3,000 to 20,000. The number of (meth) acryloyl groups (hereinafter, also referred to as “functional number”) in the component (a1) may be monofunctional, bifunctional, or trifunctional or higher, but is preferably monofunctional or bifunctional. ..
The component (a1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyhydric isocyanate compound with a (meth) acrylate having a hydroxy group. The component (a1) may be used alone or in combination of two or more.

The polyol compound used as a raw material for the component (a1) is not particularly limited as long as it is a compound having two or more hydroxy groups. Specific examples of the polyol compound include alkylene diols, polyether-type polyols, polyester-type polyols, polycarbonate-type polyols, and the like. Among these, polyester type polyols are preferable.
The polyol compound may be any of a bifunctional diol, a trifunctional triol, and a tetrafunctional or higher functional polyol, but a bifunctional diol is preferable, and a polyester type diol is more preferable.

Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; isophorone diisocyanate, norbornan diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and dicyclohexylmethane-2. , 4'-Diisocyanate, ω, ω'-diisocyanate Diisocyanate Diisocyanates such as dimethylcyclohexane; 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, trizine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene- Examples thereof include aromatic diisocyanates such as 1,5-diisocyanate.
Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable.

Urethane (meth) acrylate (a1) can be obtained by reacting a (meth) acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting the above-mentioned polyol compound with a polyhydric isocyanate compound. The (meth) acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth) acryloyl group in at least one molecule.

Specific examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 4-hydroxycyclohexyl (meth). Acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc. Hydroxyalkyl (meth) acrylate; hydroxy group-containing (meth) acrylamide such as N-methylol (meth) acrylamide; Reaction obtained by reacting diglycidyl ester of vinyl alcohol, vinylphenol, bisphenol A with (meth) acrylic acid. Things etc. can be mentioned.
Among these, hydroxyalkyl (meth) acrylate is 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 hydroxy group, the conditions for reacting at 60 to 100 ° C. for 1 to 4 hours in the presence of a solvent and a catalyst added as necessary are preferable. ..
The content of the component (a1) in the buffer layer forming composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, based on the total amount (100% by mass) of the buffer layer forming composition. , More preferably 25 to 55% by mass, and even more preferably 30 to 50% by mass.

(Polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms)
The component (a2) is a polymerizable compound having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms, and is preferably a compound having at least one (meth) acryloyl group. By using this component (a2), the film forming property of the obtained buffer layer forming composition can be improved.

The number of ring-forming atoms of the alicyclic group or the heterocyclic group contained in the component (a2) is preferably 6 to 20, more preferably 6 to 18, still more preferably 6 to 16, and even more preferably 7 to 12. Is. Examples of the atom forming the ring structure of the heterocyclic group include a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and the like.
The number of ring-forming atoms represents the number of atoms constituting the ring itself of a compound having a structure in which atoms are ring-bonded, and atoms not forming a ring (for example, hydrogen atoms bonded to atoms constituting the ring). Or, the atom contained in the substituent when the ring is substituted by the substituent is not included in the number of ring-forming atoms.

Specific components (a2) include, for example, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Examples thereof include alicyclic group-containing (meth) acrylates such as adamantan (meth) acrylate; and heterocyclic group-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate and morpholin (meth) acrylate.
The component (a2) may be used alone or in combination of two or more.
Among these, alicyclic group-containing (meth) acrylate is preferable, and isobornyl (meth) acrylate is more preferable.

The content of the component (a2) in the buffer layer forming composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, based on the total amount (100% by mass) of the buffer layer forming composition. , More preferably 25 to 55% by mass, and even more preferably 30 to 50% by mass.

(Polymerizable compound having a functional group (a3))
The component (a3) is a polymerizable compound containing a functional group such as a hydroxyl group, an epoxy group, an amide group and an amino group, and more preferably a compound having at least one (meth) acryloyl group.
The component (a3) has good compatibility with the component (a1), and it becomes easy to adjust the viscosity of the buffer layer forming composition within an appropriate range. Further, the elastic modulus and the value of tan δ of the buffer layer formed from the composition can be easily set in the above range, and the cushioning performance can be improved even if the buffer layer is made relatively thin.
Examples of the component (a3) include a hydroxyl group-containing (meth) acrylate, an epoxy group-containing compound, an amide group-containing compound, and an amino group-containing (meth) acrylate.

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, and 3-hydroxy. Examples thereof include butyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and phenylhydroxypropyl (meth) acrylate.
Examples of the epoxy group-containing compound include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether, and among these, epoxy such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate. Group-containing (meth) acrylates are preferred.
Examples of the amide group-containing compound include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, and N. -Crystalmethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide and the like can be mentioned.
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 these, a hydroxyl group-containing (meth) acrylate is preferable, and a hydroxyl group-containing (meth) acrylate having an aromatic ring such as phenylhydroxypropyl (meth) acrylate is more preferable.
The component (a3) may be used alone or in combination of two or more.

The content of the component (a3) in the buffer layer forming composition facilitates the elastic modulus and stress relaxation rate of the buffer layer within the above ranges, and improves the film forming property of the buffer layer forming composition. In addition, it is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, still more preferably 10 to 30% by mass, still more preferably 13 with respect to the total amount (100% by mass) of the composition for forming a buffer layer. It is ~ 25% by mass.
The content ratio [(a2) / (a3)] of the component (a2) to the component (a3) in the buffer layer forming composition is preferably 0.5 to 3.0, more preferably 1. It is 0 to 3.0, more preferably 1.3 to 3.0, and even more preferably 1.5 to 2.8.

(Polymerizable compounds other than the components (a1) to (a3))
The composition for forming a buffer layer may contain other polymerizable compounds other than the above-mentioned components (a1) to (a3) as long as the effects of the present invention are not impaired.
Examples of other polymerizable compounds include alkyl (meth) acrylates having an alkyl group having 1 to 20 carbon atoms; styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Vinyl compounds such as: and the like. In addition, these other polymerizable compounds may be used alone or in combination of 2 or more types.

The content of the other polymerizable compound in the buffer layer forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, still more preferably 0 to 0 to 2% by mass.

(Photopolymerization initiator)
It is preferable that the composition for forming a buffer layer further contains a photopolymerization initiator from the viewpoint of shortening the polymerization time by light irradiation and reducing the amount of light irradiation when forming the buffer layer.
Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanosen compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, etc. Examples thereof include tetramethylthium monosulfide, azobisisobutyrolenitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphin oxide and the like.
These photopolymerization initiators can be used alone or in combination of two or more.
The content of the photopolymerization initiator in the buffer layer forming composition is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the energy ray-polymerizable compound. It is by mass, more preferably 0.3 to 5 parts by mass.

(Other additives)
The composition for forming a buffer layer may contain other additives as long as the effects of the present invention are not impaired. Examples of 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 buffer layer forming composition is preferably 0.01 to 6 parts by mass with respect to 100 parts by mass of the total amount of the energy ray-polymerizable compound. More preferably, it is 0.1 to 3 parts by mass.

(Resin component)
The composition for forming a buffer layer may contain a resin component as long as the effects of the present invention are not impaired. Examples of the resin component include polyene-thiol-based resins, polyolefin-based resins such as polybutene, polybutadiene, and polymethylpentene, and thermoplastic resins such as styrene-based copolymers.
The content of these resin components in the buffer layer forming composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, still more preferably 0 to 2 by mass. It is mass%.

[Adhesive layer]
The pressure-sensitive adhesive layer preferably has an elastic modulus at 23 ° C. of 0.10 to 0.50 MPa. Circuits and the like are formed on the surface of the semiconductor wafer and are usually uneven. Since the elastic modulus of the adhesive tape is within the above range, when the adhesive tape is attached to the uneven wafer surface, the unevenness of the wafer surface and the adhesive layer are sufficiently brought into contact with each other, and the adhesiveness of the adhesive layer is appropriate. It will be possible to demonstrate it. Therefore, it is possible to reliably fix the adhesive tape to the semiconductor wafer and appropriately protect the wafer surface during backside grinding. From these viewpoints, the elastic modulus of the pressure-sensitive adhesive layer is more preferably 0.12 to 0.35 MPa. The elastic modulus of the pressure-sensitive adhesive layer means the elastic modulus before curing by energy ray irradiation when the pressure-sensitive adhesive layer is formed from an energy ray-curable pressure-sensitive adhesive, and is according to the measurement method of Examples described later. It is a value of the storage elastic modulus obtained by measurement.

The thickness (D3) of the pressure-sensitive adhesive layer is preferably 70 μm or less, more preferably less than 40 μm, further preferably 35 μm or less, and particularly preferably 30 μm or less. The thickness (D3) is preferably 5 μm or more, and more preferably 10 μm or more. When the pressure-sensitive adhesive layer is thinned in this way, the total thickness of the tape tends to be 160 μm or less as described above. Further, in the adhesive tape, the proportion of the portion having low rigidity can be reduced, so that it becomes easier to prevent the chipping of the semiconductor chip that occurs during backside grinding.

The pressure-sensitive adhesive layer is formed of, for example, an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, or the like, and an acrylic-based pressure-sensitive adhesive is preferable.
Further, the pressure-sensitive adhesive layer is preferably formed from an energy ray-curable pressure-sensitive adhesive. The pressure-sensitive adhesive layer is formed of an energy ray-curable pressure-sensitive adhesive, so that the elastic modulus at 23 ° C. is set within the above range before curing by energy ray irradiation, and the peeling force is 1000 mN / 50 mm after curing. It can be easily set as follows.

Examples of the energy ray-curable adhesive include an energy ray-curable adhesive containing an energy ray-curable compound other than the adhesive resin in addition to a non-energy ray-curable adhesive resin (also referred to as “adhesive resin I”). An agent composition (hereinafter, also referred to as “X-type pressure-sensitive adhesive composition”) can be used. Further, as an energy ray-curable adhesive, an energy ray-curable adhesive resin (hereinafter, also referred to as "adhesive resin II") in which an unsaturated group is introduced into the side chain of a non-energy ray-curable adhesive resin is used. A pressure-sensitive adhesive composition (hereinafter, also referred to as “Y-type pressure-sensitive adhesive composition”) containing as a main component and not containing an energy ray-curable compound other than the pressure-sensitive adhesive resin may also be used.
Further, as the energy ray-curable pressure-sensitive adhesive, an energy ray-curable adhesive containing both X-type and Y-type, that is, an energy ray-curable adhesive resin II and an energy ray-curable compound other than the adhesive resin. A pressure-sensitive adhesive composition (hereinafter, also referred to as “XY type pressure-sensitive adhesive composition”) may be used.
Among these, it is preferable to use an XY type pressure-sensitive adhesive composition. By using the XY type, it is possible to have sufficient adhesive properties before curing, but to sufficiently reduce the peeling force against the semiconductor wafer after curing.
However, the pressure-sensitive adhesive may be formed from a non-energy ray-curable pressure-sensitive adhesive composition that does not cure even when irradiated with energy. The non-energy ray-curable pressure-sensitive adhesive composition contains at least the non-energy ray-curable adhesive resin I, while the above-mentioned energy ray-curable pressure-sensitive adhesive resin II and the energy ray-curable compound are not contained. be.

In the following description, "adhesive resin" is used as a term to refer to one or both of the above-mentioned adhesive resin I and adhesive resin II. Specific examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, silicone resin and the like, but acrylic resin is preferable.
Hereinafter, the acrylic pressure-sensitive adhesive in which an acrylic resin is used as the pressure-sensitive adhesive resin will be described in more detail.

As the acrylic resin, the acrylic polymer (b) is used. The acrylic polymer (b) is obtained by polymerizing a monomer containing at least an alkyl (meth) acrylate, and contains a structural unit derived from the alkyl (meth) acrylate. Examples of the alkyl (meth) acrylate include those having an alkyl group having 1 to 20 carbon atoms, and the alkyl group may be linear or branched. Specific examples of alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) methacrylate, and 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 alone or in combination of two or more.

Further, the acrylic polymer (b) preferably contains a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer. The number of carbon atoms of the alkyl (meth) acrylate is preferably 4 to 12, and more preferably 4 to 6. Further, the alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is preferably an alkyl acrylate.
In the acrylic polymer (b), the alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is relative to the total amount of monomers constituting the acrylic polymer (b) (hereinafter, also simply referred to as “total amount of monomers”). It is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and further preferably 50 to 90% by mass.

The acrylic polymer (b) has an alkyl group having 4 or more carbon atoms, in addition to a structural unit derived from an alkyl (meth) acrylate, in order to adjust the elasticity and adhesive properties of the pressure-sensitive adhesive layer. It is preferably a copolymer containing a structural unit derived from an alkyl (meth) acrylate having 1 to 3 carbon atoms. The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having 1 or 2 carbon atoms, more preferably methyl (meth) acrylate, and most preferably methyl methacrylate. In the acrylic polymer (b), the alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms is preferably 1 to 30% by mass, more preferably 3 to 26% by mass, based on the total amount of the monomers. More preferably, it is 6 to 22% by mass.

The acrylic polymer (b) 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 of the functional group-containing monomer include a hydroxyl group, a carboxy group, an amino group, an epoxy group and the like. The functional group-containing monomer reacts with a cross-linking agent described later to serve as a cross-linking starting point, or reacts with an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer (b). Is possible.
Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer. These monomers may be used alone or in combination of two or more. Among these, a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxyl group-containing monomer is more preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl (meth). ) Hydroxyalkyl (meth) acrylates such as acrylates and 4-hydroxybutyl (meth) acrylates; unsaturated alcohols such as vinyl alcohols and allyl alcohols may be mentioned.
Examples of the carboxy 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 their anhydrides thereof. , 2-Carboxyethyl methacrylate and the like.

The functional group monomer is preferably 1 to 35% by mass, more preferably 3 to 32% by mass, and further preferably 6 to 30% by mass with respect to the total amount of the monomers constituting the acrylic polymer (b).
In addition to the above, the acrylic polymer (b) is derived from a monomer copolymerizable with the above acrylic monomers such as styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide. It may include a structural unit.

The acrylic polymer (b) can be used as a non-energy ray-curable adhesive resin I (acrylic resin). Further, as the energy ray-curable acrylic resin, a compound obtained by reacting the functional group of the acrylic polymer (b) with a compound having a photopolymerizable unsaturated group (also referred to as an unsaturated group-containing compound) is used. Can be mentioned.
The unsaturated group-containing compound is a compound having both a substituent capable of binding to a functional group of the acrylic polymer (b) and a photopolymerizable unsaturated group. Examples of the photopolymerizable unsaturated group include a (meth) acryloyl group, a vinyl group, an allyl group and the like, and a (meth) acryloyl group is preferable.
Examples of the substituent that can be bonded to the functional group of the unsaturated group-containing compound include an isocyanate group and a glycidyl group. Therefore, examples of the unsaturated group-containing compound include (meth) acryloyloxyethyl isocyanate, (meth) acryloyl isocyanate, and glycidyl (meth) acrylate.
Further, the unsaturated group-containing compound preferably reacts with a part of the functional group of the acrylic polymer (b), specifically, 50 to 98 mol of the functional group of the acrylic polymer (b). % Is preferably reacted with an unsaturated group-containing compound, more preferably 55 to 93 mol%. As described above, in the energy ray-curable acrylic resin, a part of the functional group remains without reacting with the unsaturated group-containing compound, so that the resin is easily crosslinked by the cross-linking agent.
The weight average molecular weight (Mw) of the acrylic resin is preferably 300,000 to 1.6 million, more preferably 400,000 to 1.4 million, and even more preferably 500,000 to 1.2 million.

(Energy ray curable compound)
As the energy ray-curable compound contained in the X-type or XY-type pressure-sensitive adhesive composition, a monomer or oligomer having an unsaturated group in the molecule and capable of polymerizing and curing by energy beam irradiation is preferable.
Examples of such an energy ray-curable compound include trimethyl propanthry (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-. Polyvalent (meth) acrylate monomers such as butylene glycol di (meth) acrylate, 1,6-hexanediol (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, epoxy ( Examples thereof include oligomers such as meth) acrylates.
Among these, urethane (meth) acrylate oligomers are preferable from the viewpoint of having a relatively high molecular weight and not easily lowering the elastic modulus of the pressure-sensitive adhesive layer.
The molecular weight of the energy ray-curable compound (weight average molecular weight in the case of an oligomer) is preferably 100 to 12000, more preferably 200 to 10000, still more preferably 400 to 8000, and even more preferably 600 to 6000.

The content of the energy ray-curable compound in the X-type pressure-sensitive adhesive composition is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and further preferably 60 to 60 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive resin. 90 parts by mass.
On the other hand, the content of the energy ray-curable compound in the XY type pressure-sensitive adhesive composition is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, still more preferably, with respect to 100 parts by mass of the pressure-sensitive adhesive resin. Is 3 to 15 parts by mass. In the XY type pressure-sensitive adhesive composition, since the pressure-sensitive adhesive resin is energy ray-curable, it is possible to sufficiently reduce the peeling force after energy ray irradiation even if the content of the energy ray-curable compound is small. Is.

(Crosslinking agent)
The pressure-sensitive adhesive composition preferably further contains a cross-linking agent. The cross-linking agent, for example, reacts with a functional group derived from a functional group monomer of the adhesive resin to crosslink the adhesive resins with each other. Examples of the cross-linking agent include isocyanate-based cross-linking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy-based cross-linking agents such as ethylene glycol glycidyl ether; hexa [1- (2-methyl) -aziridinyl. ] An aziridine-based cross-linking agent such as triphosphatriazine; a chelate-based cross-linking agent such as aluminum chelate; and the like. These cross-linking agents may be used alone or in combination of two or more.
Among these, an isocyanate-based cross-linking agent is preferable from the viewpoint of increasing the cohesive force to improve the adhesive force and the availability.
From the viewpoint of accelerating the cross-linking reaction, the amount of the cross-linking agent is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and further preferably 0 with respect to 100 parts by mass of the adhesive resin. It is 0.05 to 4 parts by mass.

(Photopolymerization initiator)
When the pressure-sensitive adhesive composition is energy ray-curable, the pressure-sensitive adhesive composition preferably further contains a photopolymerization initiator. By containing the photopolymerization initiator, the curing reaction of the pressure-sensitive adhesive composition can be sufficiently proceeded even with relatively low-energy energy rays such as ultraviolet rays.
Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanosen compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. Specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl. Examples thereof include sulphide, tetramethylthium monosulfide, azobisisobutyrolenitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphin oxide and the like.
These photopolymerization initiators may be used alone or in combination of two or more.
The blending amount of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and further preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the adhesive resin. Is.

(Other additives)
The adhesive composition may contain other additives as long as the effects of the present invention are not impaired. Examples of 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.

Further, the adhesive composition may be further diluted with an organic solvent in the form of a solution of the adhesive composition from the viewpoint of improving the applicability to the base material or the release sheet.
Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol and the like.
As these organic solvents, the organic solvent used at the time of synthesizing the adhesive resin may be used as it is, or other than the organic solvent used at the time of synthesis so that the solution of the pressure-sensitive adhesive composition can be uniformly applied. One or more organic solvents of the above may be added.

[Release sheet]
A release sheet may be attached to the surface of the adhesive tape. Specifically, the release sheet is attached to at least one of the surface of the pressure-sensitive adhesive layer of the adhesive tape and the surface of the cushioning layer. The release sheet protects the adhesive layer and the cushioning layer by being attached to these surfaces. The release sheet is detachably attached to the adhesive tape, and is removed from the adhesive tape before the adhesive tape is used (that is, before grinding the back surface of the wafer).
As the release sheet, a release sheet having at least one surface subjected to a release treatment is used, and specific examples thereof include a release sheet coated with a release agent on the surface of the base material for the release sheet.
A resin film is preferable as the base material for the release sheet, 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, polypropylene resin, and polyethylene resin. Examples thereof include the polyolefin resin of the above. 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 μm, more preferably 20 to 150 μm.

(Manufacturing method of 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 cushioning layer provided on the release sheet and the adhesive layer provided on the release sheet are attached to both sides of the base material, and the release sheet is attached to both surfaces of the buffer layer and the adhesive layer. Tapes can be manufactured. The release sheet attached to both surfaces of the cushioning layer and the pressure-sensitive adhesive layer may be appropriately peeled off and removed before using the adhesive tape.
As a method for forming a buffer layer or an adhesive layer on the release sheet, a composition for forming a buffer layer or an adhesive (adhesive composition) is directly applied on the release sheet by a known coating method and applied. A buffer layer or an adhesive layer can be formed by forming a film, irradiating the coating film with energy rays, or heat-drying the coating film.

Further, the buffer layer forming composition and the pressure-sensitive adhesive (adhesive composition) may be directly applied to both sides of the base material to form the cushioning layer and the pressure-sensitive adhesive layer. Further, the buffer layer forming composition or the pressure-sensitive adhesive (adhesive composition) is directly applied to one surface of the base material to form the buffer layer and the pressure-sensitive adhesive layer, and the other surface of the base material is further coated. The pressure-sensitive adhesive layer or the cushioning layer provided on the release sheet may be bonded.

Examples of the method for applying the composition for forming a buffer layer and the pressure-sensitive adhesive include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method. Be done. Further, in order to improve the coatability, an organic solvent may be blended with the buffer layer forming composition or the pressure-sensitive adhesive composition and coated on a release sheet in the form of a solution.

When the composition for forming a buffer layer contains an energy ray-polymerizable compound, it is preferable that the coating film of the composition for forming a buffer layer is cured by irradiating the coating film with energy rays to form a buffer layer. The cushioning layer may be cured by a single curing treatment 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 attached to the substrate, or the coating film may not be completely cured to form a semi-cured buffer layer forming film. Then, after the buffer layer forming film is attached to the base material, the buffer layer may be formed by irradiating the substrate with energy rays again to completely cure the film. Ultraviolet rays are preferable as the energy rays to be irradiated in the curing treatment. When the coating film is cured, the coating film of the buffer layer forming composition may be exposed, but the coating film is covered with a release sheet or a base material, and the coating film is irradiated with energy rays without being exposed. It is preferable to cure.

[Manufacturing method of semiconductor devices]
As described above, the adhesive tape of the present invention is used when the adhesive tape of the present invention is attached to the surface of a semiconductor wafer and the back surface of the wafer is ground in the pre-dicing method. More specifically, it is a semiconductor device. Used in the manufacturing method of.

Specifically, the method for manufacturing a semiconductor device of the present invention includes at least the following steps 1 to 4.
Step 1: The above adhesive tape is attached to the surface of the semiconductor wafer. Step 2: A step of forming a groove from the front surface side of the semiconductor wafer or forming a modified region inside the semiconductor wafer from the front surface or the back surface of the semiconductor wafer. Step 3: The semiconductor wafer to which the adhesive tape is attached to the front surface and the groove or modified region is formed is ground from the back surface side to be individualized into a plurality of chips starting from the groove or modified region. Step Step 4: A step of peeling the adhesive tape from the fragmented semiconductor wafer (that is, a plurality of semiconductor chips).

Hereinafter, each step of the method for manufacturing the semiconductor device will be described in detail.
(Step 1)
In step 1, the adhesive tape of the present invention is attached to the surface of the semiconductor wafer via the adhesive layer. This step may be performed before the step 2 described later, but may be performed after the step 2. For example, when forming a modified region on a semiconductor wafer, it is preferable to perform step 1 before step 2. On the other hand, when a groove is formed on the surface of the semiconductor wafer by dicing or the like, step 1 is performed after step 2. That is, the adhesive tape is attached to the surface of the wafer having the groove formed in the step 2 described later in the main step 1.
The semiconductor wafer used in the present manufacturing method may be a silicon wafer, a wafer such as gallium arsenide or arsenide, or a glass wafer. The thickness of the semiconductor wafer before grinding is not particularly limited, but is usually about 500 to 1000 μm. Further, a circuit is usually formed on the surface of a semiconductor wafer. The circuit can be formed on the wafer surface by various methods including a conventionally used general-purpose method such as an etching method and a lift-off method.

(Step 2)
In step 1, a groove is formed from the front surface side of the semiconductor wafer, or a modified region is formed inside the semiconductor wafer from the front surface or the back surface of the semiconductor wafer.
The groove formed in this step is a groove having a depth shallower than the thickness of the semiconductor wafer. The groove can be formed by dicing using a conventionally known wafer dicing device or the like. Further, the semiconductor wafer is divided into a plurality of semiconductor chips along the groove in step 3 described later.
Further, the modified region is a brittle portion of the semiconductor wafer, and the semiconductor wafer is thinned by grinding in the grinding process, or the semiconductor wafer is destroyed by the force applied by the grinding, and the semiconductor chip is destroyed. This is the area that serves as the starting point for individualization. That is, in step 2, the groove and the modified region are formed along the dividing line when the semiconductor wafer is divided into pieces into semiconductor chips in step 3 described later.
The modified region is formed by irradiating a laser focused on the inside of the semiconductor wafer, and the modified region is formed inside the semiconductor wafer. The laser irradiation may be performed from the front surface side or the back surface side of the semiconductor wafer. In the embodiment 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 via the adhesive tape.
The semiconductor wafer to which the adhesive tape is attached and which has a groove or a modified region is placed on a chuck table and is adsorbed and held by the chuck table. At this time, the surface side of the semiconductor wafer is arranged on the table side and is adsorbed.

(Step 3)
After the steps 1 and 2, the back surface of the semiconductor wafer on the chuck table is ground to separate the semiconductor wafer into a plurality of semiconductor chips.
Here, when a groove is formed in the semiconductor wafer, the back surface grinding is performed so as to thin the semiconductor wafer at least to a position reaching the bottom of the groove. By this backside grinding, the groove becomes a notch penetrating the wafer, and the semiconductor wafer is divided by the notch and individualized into individual semiconductor chips.
On the other hand, when the modified region is formed, the ground surface (back surface of the wafer) may reach the modified region by grinding, but may not reach the modified region strictly. That is, the semiconductor wafer may be ground from the modified region to a position close to the modified region so that the semiconductor wafer is broken and separated into semiconductor chips. For example, the actual individualization of the semiconductor chip may be performed by attaching the VIP-up tape described later and then stretching the VIP-up tape.

The shape of the individualized semiconductor chip may be a square shape or an elongated shape such as a rectangle. The thickness of the fragmented semiconductor chip is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. The size of the fragmented semiconductor chip is not particularly limited, but the chip size is preferably less than 50 mm ² , more preferably less than 30 mm ² , and even more preferably less than 10 mm ² .
When the adhesive tape of the present invention is used, even with such a thin and / or small semiconductor chip, the semiconductor chip is chipped during backside grinding (step 3) and when the adhesive tape is peeled off (step 4). Is prevented.

(Step 4)
Next, the adhesive tape for semiconductor processing is peeled off from the fragmented semiconductor wafer (that is, a plurality of semiconductor chips). This step is performed, for example, by the following method.
First, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape is formed from an energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer is cured by irradiating with energy rays. Next, a pickup tape is attached to the back surface side of the fragmented semiconductor wafer, and the position and direction are adjusted so that the pickup can be picked up. At this time, the ring frame arranged on the outer peripheral side of the wafer is also attached to the pick-up tape, and the outer peripheral edge portion of the pickup tape is fixed to the ring frame. The wafer and the ring frame may be bonded to the pickup tape at the same time, or may be bonded at different timings. Next, the adhesive tape is peeled off from the plurality of semiconductor chips fixed on the pickup tape.
After that, a plurality of semiconductor chips on the pickup tape are picked up and fixed on a substrate or the like to manufacture a semiconductor device.
The pickup tape is not particularly limited, but is composed of, for example, a base material and a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer provided on one surface of the base material.

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

The measurement method and evaluation method in the present invention are as follows.
[Mass average molecular weight (Mw)]
It was measured under the following conditions using a gel permeation chromatograph device (manufactured by Tosoh Corporation, product name "HLC-8020"), and the value measured in terms of standard polystyrene was used.
(Measurement condition)
-Column: "TSK guard group HXL-H""TSK gel GMHXL (x2)""TSK gel G2000HXL" (all manufactured by Tosoh Corporation)
-Column temperature: 40 ° C
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min
[Young's modulus of the base material]
The Young's modulus of the substrate was measured according to JIS K-7127 (1999) at a test speed of 200 mm / min.

[Maximum elastic modulus of buffer layer and tan δ]
Examples described later except that a release sheet (manufactured by Lintec Corporation, trade name "SP-PET38131", thickness: 38 μm) is used instead of the base material, and the thickness of the obtained buffer layer is 200 μm. , A test buffer layer was prepared in the same manner as the buffer layer of the comparative example. After removing the release sheet on the test buffer layer, a test piece cut to a predetermined size was used by a dynamic viscoelastic device (manufactured by Orientech, trade name "Rheovibron DDV-II-EP1"). The loss elastic modulus and the storage elastic modulus were measured at a frequency of 11 Hz in a temperature range of −20 to 150 ° C.
The value of "loss elastic modulus / storage elastic modulus" at each temperature was calculated as tan δ of that temperature, and the maximum value of tan δ in the range of −5 to 120 ° C. was defined as the “maximum value of tan δ of the buffer layer”.
[Stress relaxation rate of buffer layer]
A test buffer layer was prepared on a release sheet in the same manner as above, and cut into 15 mm × 140 mm to form a sample. Using a universal tensile tester (Autograph AG-10kNIS manufactured by SHIMADZU), grasp 20 mm at both ends of this sample, pull at a speed of 200 mm per minute, stress A (N / m2) when stretched by 10%, and tape. The stress B (N / m2) 1 minute after the extension stop was measured. From these values of stresses A and B, (AB) / A × 100 (%) was calculated as the stress relaxation rate.

[Elastic modulus of adhesive layer]
Obtained by laminating a single pressure-sensitive adhesive layer formed from a solution of the pressure-sensitive adhesive composition used in Examples and Comparative Examples using a viscoelasticity measuring device (manufactured by Rheometrics, device name "DYNAMIC ANALYZER RDAII"). A sample having a diameter of 8 mm and a thickness of 3 mm was measured by a torsional shear method at a storage elastic modulus G'at 1 Hz in an environment of 23 ° C., and the obtained value was taken as the elastic modulus of the pressure-sensitive adhesive layer.

[Measurement of peeling force]
The adhesive tape with a release sheet obtained in Examples and Comparative Examples was cut into a length of 250 mm and a width of 50 mm, the release sheet was peeled off, and the adhesive tape was attached to an 8-inch silicon mirror wafer using a 2 kg rubber roll. After allowing to stand for 20 minutes, ultraviolet irradiation was performed from the tape side under the conditions of an illuminance of 230 mW / cm ² and a light intensity of 380 mJ / cm ² with an ultraviolet irradiation device (manufactured by Lintec Corporation, trade name "RAD-2000"). The adhesive tape whose adhesive layer was cured by ultraviolet irradiation was peeled off by a universal testing machine (manufactured by A & D Co., Ltd., trade name "Tencilon") at a peeling speed of 4 mm / sec and a peeling angle of 180 °, and the peeling force was measured. .. This test was conducted at room temperature (23 ° C.) and under 50% RH conditions.

[Measurement of adhesive tape thickness]
The total thickness of the adhesive tape, the base material, the pressure-sensitive adhesive layer, and the thickness of the buffer layer were measured with a constant pressure thickness measuring device (manufactured by Teclock Co., Ltd., PG-02). At this time, arbitrary 10 points were measured and the average value was calculated.
In this embodiment, the total thickness of the adhesive tape is a value obtained by measuring the thickness of the adhesive tape with a release sheet and subtracting the thickness of the release sheet from the thickness. Further, the thickness of the buffer layer is a value obtained by subtracting the thickness of the substrate from the thickness of the substrate with the buffer layer. The thickness of the pressure-sensitive adhesive layer is a value obtained by subtracting the thickness of the cushioning layer and the base material from the total thickness of the pressure-sensitive adhesive tape.

(Performance evaluation)
[Chipping test 1]
A groove is formed from the wafer surface of a silicon wafer with a diameter of 12 inches (30.48 cm), then an adhesive tape is attached to the wafer surface, and the wafer is individualized by backside polishing. It was individualized into chips with a size of 1 mm square. After that, without peeling off the adhesive tape, observe the corners of the chips separated from the ground surface of the wafer with a digital microscope (VE-9800 manufactured by KEYENCE CORPORATION), and observe the presence or absence of chipping at the corners of each chip. The chipping occurrence rate in the chip was measured and evaluated according to the following evaluation criteria.
A: less than 1.0%, B: 1.0 to 2.0%, C: more than 2.0%

[Chip crack test 2]
First, an adhesive tape was attached to the surface of a silicon wafer having a diameter of 12 inches (30.48 cm). Next, a lattice-shaped modified region was formed on the silicon wafer using a laser saw from the surface opposite to the surface to which the adhesive tape was attached. The grid size was 1 mm square. Subsequently, using a back surface grinding device, the chips were ground to a thickness of 30 μm and individualized into 1 mm square chips. After the grinding process, energy rays are irradiated, and the dicing tape (Lintec Corporation, trade name "D-821HS") is attached to the opposite surface of the adhesive tape, and then the adhesive tape is not peeled off and is individually passed through the dicing tape. The fragmented chips were observed with a digital microscope, the presence or absence of chip cracks at each chip angle was observed, the chip crack occurrence rate in 700 chips was measured, and evaluation was performed according to the following evaluation criteria.
A: less than 1.0%, B: 1.0 to 2.0%, C: more than 2.0%

[Peeling evaluation 1]
The adhesive tape with a release sheet obtained in Examples and Comparative Examples was set on a tape laminator (manufactured by Lintec Corporation, trade name "RAD-3510") while peeling off the release sheet, and a groove was formed on the wafer surface by a dicing method. It was attached to the formed 12-inch silicon wafer (thickness 760 μm) under the following conditions.
Roll height: 0 mm Roll temperature: 23 ° C (room temperature)
Table temperature: 23 ° C (room temperature)
The obtained silicon wafer with adhesive tape was individualized into a thickness of 30 μm and a chip size of 1 mm square by backside grinding (dicing method). Adhesive tape with individualized chips is irradiated with ultraviolet rays (conditions: 230 mW / cm ² , 380 mJ / cm ² ) from the tape side with a dicing tape mounter (manufactured by Lintec Corporation, product name "RAD-2700"). The adhesive was cured. Then, in the same RAD-2700 apparatus, a dicing tape (manufactured by Lintec Corporation, trade name "D-821HS") was attached from the chip side. At this time, a jig called a ring frame used in the pickup process was also attached to the pickup tape. Next, the cured adhesive tape was peeled off in the RAD-2700 apparatus. 700 chips after the adhesive tape was peeled off were observed through a dicing tape with a digital microscope (manufactured by KEYENCE CORPORATION, trade name "VE-9800"), and the incidence of chip chipping was measured. The value obtained by subtracting the occurrence rate in the chipping test 1 from the same occurrence rate was defined as the occurrence rate of peeling evaluation 1, and was evaluated according to the following evaluation criteria.
OK: less than 1.0%, NG: 1.0% or more

[Peeling evaluation 2]
A 12-inch (30.48 cm) silicon wafer (30.48 cm) silicon wafer (30.48 cm) using a tape laminator (manufactured by Lintec Corporation, trade name "RAD-3510") while peeling off the release sheet of the adhesive tape with a release sheet obtained in Examples and Comparative Examples. It was attached to a thickness of 760 μm) under the following conditions.
Roll height: 0 mm Roll temperature: 23 ° C (room temperature)
Table temperature: 23 ° C (room temperature)
Next, laser irradiation was performed with a laser saw from the surface opposite to the surface to which the tape was attached to form a grid-like modified region on the wafer. The grid size was 1 mm square. The obtained silicon wafer with adhesive tape was individualized into a thickness of 30 μm and a chip size of 1 mm square by back surface grinding. Adhesive tape with individualized chips is irradiated with ultraviolet rays (conditions: 230 mW / cm ² , 380 mJ / cm ² ) from the tape side with a dicing tape mounter (manufactured by Lintec Corporation, product name "RAD-2510"). The adhesive was cured. Then, in the same RAD-2510 device, a pickup tape (manufactured by Lintec Corporation, trade name "D-821HS") was attached from the chip side. At this time, the ring frame used in the pickup process was also attached to the pickup tape. Next, the cured adhesive tape was peeled off in the RAD-2510 device. 700 chips after peeling the adhesive tape were observed through a dicing tape with a digital microscope (manufactured by KEYENCE CORPORATION, trade name "VE-9800"), and the occurrence rate of chip cracks was measured. The value obtained by subtracting the occurrence rate in the chip crack test 1 from the same occurrence rate was defined as the occurrence rate of peeling evaluation 1, and was evaluated according to the following evaluation criteria.
OK: less than 1.0%, NG: 1.0% or more

The mass parts of the following Examples and Comparative Examples are all solid content values.
[Example 1]
(1) Synthesis of Urethane Acrylate-based Oligomer A bifunctional bifunctional product having a mass average molecular weight (Mw) of 5000 by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyester diol with an isophorone diisocyanate with a 2-hydroxyethyl acrylate. A urethane acrylate-based oligomer (UA-1) was obtained.
(2) Preparation of composition for forming a buffer layer 40 parts by mass of the urethane acrylate-based oligomer (UA-1) synthesized above, 40 parts by mass of isobornyl acrylate (IBXA), and 20 parts by mass of phenylhydroxypropyl acrylate (HPPA). 1-Hydroxycyclohexylphenylketone (manufactured by BASF, product name "Irgacure 184") 2.0 parts by mass and 0.2 parts by mass of a phthalocyanine pigment as a photopolymerization initiator. A forming composition was prepared.
(3) Preparation of Adhesive Composition An acrylic polymer obtained by copolymerizing 52 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA). 2-methacryloyloxyethyl isocyanate (MOI) is reacted with (b) so as to be added to 90 mol% of the hydroxyl groups of the total hydroxyl groups of the acrylic polymer (b), and an energy ray-curable acrylic resin is used. (Mw: 500,000) was obtained.
To 100 parts by mass of this energy ray-curable acrylic resin, 6 parts by weight of a polyfunctional urethane acrylate (trade name: Shikou UT-4332, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), which is an energy ray-curable compound, an isocyanate-based cross-linking agent. (Manufactured by Toyochem Co., Ltd., trade name: BHS-8515) is added in an amount of 0.375 parts by mass based on solid content, and 1 part by weight of a photopolymerization initiator composed of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide is added. Then, the coating liquid of the pressure-sensitive adhesive composition was prepared by diluting with a solvent.
(4) Preparation of Adhesive Tape The cushioning layer forming composition obtained above is applied to one surface of a polyethylene terephthalate film (Young's modulus: 2500 MPa) having a thickness of 50 μm as a base material, and the illuminance is 160 mW / cm. ^2. The composition for forming a buffer layer was cured by irradiating with ultraviolet rays under the condition of an illuminance amount of 500 mJ / cm ² , to obtain a buffer layer having a thickness of 13 μm.
Further, on the peeling surface of the peeling sheet (manufactured by Lintec Corporation, trade name: SP-PET38131) in which the base material of the peeling sheet is a polyethylene terephthalate film, the thickness of the coating liquid of the pressure-sensitive adhesive composition obtained above is dried. The coating was applied so as to have a diameter of 20 μm, and the mixture was heated and dried to form an adhesive layer on the release sheet. This pressure-sensitive adhesive layer was attached to the other surface of the base material with a cushioning layer to obtain an adhesive tape with a release sheet.
The elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. was 0.15 MPa. The storage elastic modulus of the buffer layer was 250 MPa, the stress relaxation rate was 90%, and the maximum value of tan δ was 1.24.

[Examples 2 to 8, Comparative Examples 1 to 15]
The procedure was carried out in the same manner as in Example 1 except that the thicknesses of the base material, the buffer layer, and the pressure-sensitive adhesive layer were changed as shown in Table 1.
As the base material in each Example and Comparative Example, a polyethylene terephthalate film having the same Young's modulus as in Example 1 was used.

表中の“－”は未実施であることを示す。

"-" In the table indicates that it has not been implemented.

As described above, in Examples 1 to 8, the total thickness of the adhesive tape was 160 μm or less, the thickness ratio (D2 / D1) was 0.7 or less, and the peeling force was 1000 mN / 25 mm or less. The results of the peeling evaluation were good, and in the pre-dicing method, chipping was less likely to occur when the back surface of the semiconductor wafer was ground and when the adhesive tape was peeled off.
On the other hand, in Comparative Examples 1 to 10, the thickness of the buffer layer became large and the thickness ratio (D2 / D1) was larger than 0.7, so that the chipping occurrence rate became high in the chipping test and the semiconductor wafer. When grinding the back surface of the semiconductor chip, the semiconductor chip is likely to be chipped. Furthermore, as the thickness ratio (D2 / D1) increases, the peeling force tends to increase, and as shown in Comparative Examples 3 and 4, there is a high possibility that the semiconductor chip will be chipped when the adhesive tape is peeled off.
Further, in Comparative Examples 11 to 13, since the total thickness of the adhesive tape was large, the peeling force was large, and the semiconductor wafer was chipped when the adhesive tape was peeled off. Further, in Comparative Example 14, since both the thickness ratio (D2 / D1) and the total thickness of the adhesive tape were large, the semiconductor wafer was chipped both when the back surface of the semiconductor wafer was ground and when the adhesive tape was peeled off. occured. Also in Comparative Example 15, since the total thickness of the tape is large, chip chipping and the like also occur.

Claims (12)

In the process of grinding the back surface of a semiconductor wafer having grooves formed on the surface of the semiconductor wafer or having a modified region formed on the semiconductor wafer, and the semiconductor wafer being fragmented into semiconductor chips by the grinding, the surface of the semiconductor wafer is formed. Adhesive tape for semiconductor processing that is attached and used.
A base material, a cushioning layer provided on one surface of the base material, and an adhesive layer provided on the other side of the base material are provided.
The thickness of the pressure-sensitive adhesive layer (D3) is 30 μm or less, the total thickness of the adhesive tape for semiconductor processing is 160 μm or less, and the thickness of the buffer layer (D2) is the thickness of the base material (D1). ) Is 0.7 or less (D2 / D1), and the peeling force for the semiconductor wafer is 1000 mN / 50 mm or less. The adhesive tape for semiconductor processing according to claim 1, wherein the Young's modulus of the base material is 1000 MPa or more. The adhesive tape for semiconductor processing according to claim 1 or 2, wherein the thickness (D1) of the base material is 110 μm or less. The adhesive tape for semiconductor processing according to any one of claims 1 to 3, wherein the base material has at least a polyethylene terephthalate film. The pressure-sensitive adhesive tape for semiconductor processing according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer is formed of an energy ray-curable pressure-sensitive adhesive. The pressure-sensitive adhesive tape for semiconductor processing according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive layer has an elastic modulus of 0.10 to 0.50 MPa at 23 ° C. The pressure-sensitive adhesive layer is functional with a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms and a structural unit derived from an alkyl (meth) acrylate having an alkyl group having 1 to 3 carbon atoms. The pressure-sensitive adhesive tape for semiconductor processing according to any one of claims 1 to 6, which is formed from a pressure-sensitive adhesive composition containing an acrylic resin having a structural unit derived from a group-containing monomer. The adhesive tape for semiconductor processing according to any one of claims 1 to 7, wherein the cushioning layer has a storage elastic modulus of 100 to 1500 MPa at 23 ° C. The adhesive tape for semiconductor processing according to any one of claims 1 to 8, wherein the stress relaxation rate of the buffer layer is 70 to 100%. The buffer layer comprises urethane (meth) acrylate (a1), a polymerizable compound (a2) having an alicyclic group or a heterocyclic group having 6 to 20 ring-forming atoms, and a polymerizable compound (a3) having a functional group. The adhesive tape for semiconductor processing according to any one of claims 1 to 9, which is formed from the composition for forming a buffer layer containing the same. The adhesive tape for semiconductor processing according to claim 10, wherein the component (a2) is an alicyclic group-containing (meth) acrylate and the component (a3) is a hydroxyl group-containing (meth) acrylate. The step of attaching the adhesive tape for semiconductor processing according to any one of claims 1 to 11 to the surface of the semiconductor wafer, and
A process of forming a groove from the front surface side of the semiconductor wafer or forming a modified region inside the semiconductor wafer from the front surface or the back surface of the semiconductor wafer.
A semiconductor wafer on which the adhesive tape for semiconductor processing is attached to the front surface and in which the groove or the modified region is formed is ground from the back surface side and individualized into a plurality of chips starting from the groove or the modified region. And the process of making
The process of peeling the adhesive tape for semiconductor processing from the plurality of chips,
A method for manufacturing a semiconductor device.