TW201420714A - Radiation-curing adhesive tape for dicing - Google Patents

Abstract

Provided is a radiation-curing adhesive tape for dicing capable of easy pickup without any residual adhesive in the pickup step even for, e.g., a semiconductor chip on which a through electrode is provided. This radiation-curing adhesive tape (1) for dicing has a radiation-curing adhesive layer (3) provided on a substrate sheet (2), wherein the tape is characterized in that Young's modulus after radiation curing/Young's modulus before radiation curing, which is the ratio of the Young's modulus after radiation curing to the Young's modulus before radiation curing, is 1.0-1.8.

Description

Adhesive tape for radiation hardening wafer cutting

The present invention relates to an adhesive tape used for fixing a workpiece such as a semiconductor wafer when dicing a semiconductor wafer or the like to form a chip.

A conventional semiconductor device is manufactured by electrically bonding a semiconductor wafer provided on a substrate by wire bonding. In recent years, in response to the demand for further miniaturization, thinner, and lighter weight of the device, electronic components starting from the use of semiconductor devices inside such devices have been demanded. In order to miniaturize an electronic component, for example, it is proposed to laminate a semiconductor wafer to realize a three-dimensional mounting technique of high-density mounting (for example, refer to Patent Document 1). Further, a method of performing a three-dimensional mounting technique, for example, a method of forming an electrode (through electrode) that penetrates a wafer, and a semiconductor package structure in which a wafer for mounting an interposer is mounted via the electrode layer (for example, a reference patent) Literature 2).

Reviewing the process of cutting a wafer having a through electrode into a small piece (semiconductor wafer) (dicing step), and performing a crystallization step (pick-up step) of the semiconductor wafer Radiation hardening Adhesive tape for wafer cutting processing of adhesive layer.

When an adhesive tape for wafer dicing having a radiation-curable adhesive layer is used, the wafer must be sufficiently held at the cutting step. However, a wafer having a through electrode is usually provided with a protruding portion of a through electrode having a height of 3 to several tens of μm on one or both sides. Therefore, even if the conventional adhesive tape for cutting processing is attached, the projection cannot be followed, and most of the wafers cannot be held. Further, this result may cause voids in the peripheral portion of the protrusion of the through electrode. Usually, in the cutting step, a wafer is formed into a wafer by a rotary blade called a blade. When there is a gap between the adhesive layer and the peripheral portion of the protrusion of the through electrode and cannot be sufficiently held, the wafer vibrates due to the impact at the time of cutting and causes the blade to collide with the wafer, causing wafer defects (cracking) to lower the processing of the wafer. Sex.

In order to solve the problem in the dicing step, it is proposed to make the gel fraction of the adhesive layer and the storage elastic modulus at 10 ° C into a radiation-curable adhesive tape for wafer-cutting in a specific range (see, for example, Patent Document 3). The adhesive tape for radiation-curable wafer dicing of Patent Document 3 solves the above problems in the cutting step by an adhesive layer having a gel fraction and a storage modulus in a specific range.

[Practical Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-50738

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-236245

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2006-202926

However, in the adhesive tape for radiation-curable wafer dicing of Patent Document 3, after the dicing is performed, the adhesive layer is cured by radiation to reduce the adhesive force, and the adhesive layer is hardened and shrunk to enclose the adhesive layer. The protrusion of the surface of the wafer such as the through electrode causes a problem that the cut semiconductor wafer cannot be picked up satisfactorily. In the adhesive tape for radiation-curable wafer dicing of the above-mentioned Patent Document 3, an adhesive containing a gas generating agent that generates a gas due to stimulation is used. However, in a mechanism for generating a gas in an adhesive, since the adhesive becomes brittle, adhesion of the adhesive debris to the wafer (residue of the adhesive) may occur, and the problem of handleability is lowered.

Therefore, the present invention provides a radiation-hardened wafer dicing adhesive which can be easily crystallized without causing adhesive residue to remain in the crystallization step even in a semiconductor wafer or the like provided with a through electrode. Tape for the purpose.

In order to solve the problem, the radiation-curable adhesive tape for dicing a wafer of the present invention is a radiation-curable adhesive tape provided with a radiation-curable adhesive layer on a substrate sheet, and is characterized by being a radiation-hardened Young's The ratio of the rate to the Young's rate before radiation hardening is 1.0 to 1.8.

In the above-described adhesive tape for radiation-curable wafer dicing, it is preferable that the storage elastic modulus G' of the adhesive layer before radiation hardening is 1.8 × 10 ⁴ to 4.7 × 10 ⁴ Pa.

Further, in the above-mentioned adhesive tape for radiation-curable wafer dicing, it is preferable that the loss coefficient tan δ of the adhesive layer before radiation hardening is 0.20 to 0.35.

Further, the above-described adhesive tape for radiation-curable wafer dicing is preferably used for dicing a semiconductor wafer.

Further, in the above-described adhesive tape for radiation-curable wafer dicing, it is preferable that the semiconductor wafer has a protrusion or a step on a surface to be bonded to the pressure-sensitive adhesive layer.

According to the present invention, the rupture of the dicing step can be reduced, and even in the case of the semiconductor wafer provided with the through electrode, the adhesive does not remain in the crystallization step, and the crystallization can be easily performed.

[In order to implement the invention]

In the following, embodiments of the present invention will be described in detail.

In the radiation-curable wafer-cut adhesive tape 1 according to the embodiment of the present invention, at least one adhesive layer 3 is formed on at least one surface of the base material sheet 2. 1 is a schematic cross-sectional view showing a preferred embodiment of the radiation-curable wafer-cut adhesive tape 1 of the present invention, and the radiation-curable wafer-cut adhesive tape 1 has a substrate sheet 2 on a substrate sheet 2 An adhesive layer 3 is formed thereon.

The radiation-curable adhesive tape 1 for radiation-curable wafer dicing according to the embodiment of the present invention is a ratio of the Young's ratio after radiation hardening to the Young's ratio before radiation hardening (Young's rate after radiation hardening/radiation hardening) The former Young's rate) is 1.0 to 1.8.

Adhesive tape on the radiation-hardened wafer cutting adhesive tape 1 When the wafer having the protrusions or the step on the surface of the layer 3 is bonded to the radiation-curable wafer-cut adhesive tape 1, it is preferable to embed the protrusion or the step almost completely in the adhesive layer 3. When there is a gap between the protrusion or the step and the radiation-curable wafer-cut adhesive tape 1, the wafer is greatly vibrated by the vibration of the rotary blade (blade) at the cutting step, causing the blade or the adjacent wafer. Contact creates a problem with wafer cracking.

Further, when the protrusion or the step is almost completely buried in the adhesive layer 3, the influence of the vibration of the rotary blade can be reduced, but when the radiation-curable adhesive is used in the adhesive constituting the adhesive layer 3, the adhesive layer 3 is formed. The film is hardened in a state in which it is in close contact with the protrusions or the step, and the adhesive layer 3 covers the protrusions or the step difference in the crystallization step, resulting in a problem that crystals cannot be taken.

Here, the radiation curable adhesive refers to an adhesive composition containing at least a compound (a) having a carbon-carbon unsaturated bond at the end of the molecule and a compound called a starter which is subjected to radiation to generate a radical. By irradiating the radiation, the initiator is activated and activated by the carbon-carbon unsaturated bond at the end of the generated radical bond, and bonded to the subsequent compound (a), between the compounds (a) Form crosslinks.

Before the cross-linking is formed, since the plurality of compounds (a) dispersed in the adhesive are crosslinked to form and bond, the adhesive becomes harder after crosslinking than before crosslinking. In the state in which the cross-linking reaction is caused by adhesion to the protrusions or the step, the hardened adhesive covers the protrusions or the step difference, and the peeling is smoothly prevented. In particular, in a wafer having a through electrode, when a protrusion is formed in the inside of the wafer, the strength of the wafer is remarkably weakened, and when the peeling is prevented, the wafer is likely to be broken. Covering due to hardening of the adhesive When the object or the step is inferior, it can be suppressed by adjusting the degree of hardening of the adhesive.

The tensile modulus of the adhesive tape 1 for radiation-hardened wafer cutting is used as an index of the degree of hardening of the adhesive. The ratio of the tensile elastic modulus before the radiation hardening to the tensile elastic modulus after hardening (the tensile elastic modulus after radiation hardening/the tensile elastic modulus before the hardening) is approximately close to 1, which means that the hardness change before and after the crosslink formation is small. The meaning. The radiation hardening type adhesive layer 3 is hardened by irradiation of radiation as described above, and usually the above ratio is more than 1. When the ratio is 1.8 or less, there are few cases where the protrusion or the step is covered, and the crystal extraction can be easily performed. When it is larger than 1.8, a case where a protrusion or a step is covered is formed, and the stress applied to the wafer at the time of the protrusion of the crystal extraction step becomes large, and crystals cannot be taken and a wafer breakage occurs at the same time.

Further, the tensile modulus at this time is a value obtained in accordance with JIS K 7127:1999. Further, in general, the substrate sheet 2 is thicker and more rigid than the adhesive layer 3, but the ratio of the tensile modulus of the adhesive tape 1 for radiation-hardened wafer cutting can be compared with only the adhesive. The tensile modulus of the layer 3.

Here, the amount of irradiation of the radiation is not particularly limited. For example, in the case of ultraviolet rays, it is preferably 100 to 1000 mJ/cm ^{2 and more} preferably 200 to 500 mJ/cm ² .

In order to prevent the semiconductor wafer from being broken, the storage elastic modulus G' of the adhesive layer 3 before the radiation hardening is preferably 1.8 × 10 ⁴ to 4.7 × 10 ⁴ Pa, more preferably 2.0 × 10 ⁴ to 4.7 × 10 ⁴ . When G' is less than 1.8 × 10 ⁴ Pa, the adhesive layer 3 can be sufficiently adhered to the projections or the step, but since the adhesive layer 3 is too soft, it is impossible to suppress the vibration due to the rotary blade during the cutting step, and cracking occurs. Further, when it is more than 4.7 × 10 ⁴ Pa, the adhesive layer 3 cannot be sufficiently adhered to the projections or the step to cause voids, and eventually cracks due to vibration of the rotary blade in the cutting step.

Further, in order to maintain the adhesive layer 3 in a state of being sufficiently adhered to the projections or the step, the loss coefficient tan δ of the adhesive layer 3 before the radiation hardening is preferably 0.20 to 0.35, more preferably 0.25 to 0.35. The loss coefficient tan δ is expressed by the ratio (G"/G') of the storage elastic modulus G' and the loss elastic modulus G". When the tan δ is too small, even if the adhesive layer 3 can be sufficiently adhered to the projections or the step, it is difficult to maintain the close contact state due to the large anti-reflection ability. When the tan δ is too large, since the anti-reflection ability is small, it becomes difficult to convey the stress from the underlying protruding tool when the crystal is taken after the singulation. When the loss coefficient tan δ of the adhesive layer 3 is less than 0.20, the adhesion state cannot be maintained, and a gap is formed between the wafer and the adhesive tape, which may cause a problem of cracking due to the above mechanism. When the loss coefficient tan δ of the adhesive layer 3 is more than 0.35, it is difficult to convey the stress from the underlying protruding tool when the crystal is taken after the singulation, and the height of the projection cannot be increased, which may increase the damage of the wafer.

Each component of the radiation-curable wafer-cut adhesive tape 1 of the present embodiment will be described in detail below.

(Substrate sheet 2)

The resin constituting the base material sheet 2 is not particularly limited, and a resin which can form a sheet can be used. For example, polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene/propylene copolymer, propylene copolymer, ethylene-propylene-di can also be used. Ene copolymer sulfide, polybutene, polybutadiene, polymethylpentene, ethylene-(meth)acrylic acid copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-(meth)acrylic acid Ethyl ester copolymer, ethylene-butyl (meth)acrylate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride-vinyl acetate copolymer, polyurethane, polyamine, Ionic polymer, nitrile rubber, butyl rubber, styrene isopentenylene rubber, styrene butadiene rubber, natural rubber, and water or modified substances thereof. These resins may be used singly or in combination of two or more kinds, or may be composed of a plurality of layers of two or more layers.

The thickness of the base material sheet 2 is not particularly limited. When it is too thin, it is difficult to handle. When it is too thick, it is difficult to convey the stress of the protrusion tool during the crystallization step, so it is preferably 50 to 150 μm, more preferably 70 to 100 μm.

In order to improve the adhesion, the surface of the base material sheet 2 to which the adhesive layer 3 is bonded may be subjected to corona treatment, and the treatment of the underlayer or the like may be performed.

(adhesive layer 3)

The adhesive composition constituting the adhesive layer 3 is preferably, for example, described in JP-A-7-135189, and is not limited thereto, and may be used for a rubber-based or acrylic-based base polymer. A compound having at least two radiation-polymerizable carbon-carbon double bonds in a blended molecule (hereinafter referred to as a photopolymerizable compound) and a photopolymerization initiator are used, or an acrylic base polymer is added thereto. A compound of carbon-carbon double bonds.

A method of introducing a carbon-carbon double bond into an acrylic polymer, Other restrictions, for example, by copolymerizing a monomer having a functional group as a copolymerizable monomer to prepare a functional group-containing acrylic polymer, and then having a functional group in the functional group-containing acrylic polymer The compound having a functional group and a carbon-carbon double bond obtained by the reaction is subjected to a condensation reaction or addition with a functional group-containing acrylic polymer while maintaining the radiation curability (radiation polymerizability) of the carbon-carbon double bond. A method of preparing an acrylic polymer having a carbon-carbon double bond in a molecule, and the like.

The rubber-based or acrylic-based base polymer is a rubber-based polymer such as natural rubber or various synthetic rubbers, or a polyalkyl (meth)acrylate, an alkyl (meth)acrylate, or an alkyl (meth)acrylate. An acrylic polymer such as a copolymer of an ester and an unsaturated monomer copolymerizable therewith. When ethyl acrylate, butyl acrylate or methoxyethyl acrylate is used as a monomer constituting the matrix polymer, it is preferred because the crystallinity can be further improved.

Photopolymerizable compounds such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(a) An ester of (meth)acrylic acid with a polyhydric alcohol such as acrylate, neopentyl di(meth) acrylate, dipentaerythritol hexa(meth) acrylate or glycerol di(meth) acrylate; Ester acrylate oligomer; cyanate ester compound having a carbon-carbon double bond group such as 2-propenyl-di-3-butenyl cyanate; ginseng (2-propenyloxyethyl) Isocyanate, ginseng (2-methylpropenyloxyethyl)isocyanate, 2-hydroxyethylbis(2-propenyloxyethyl)isocyanate, bis(2-propenyloxyethyl)2-[(5-propylene) Oxyhexyl)-oxy]ethyl isocyanate, 1,3-(dipropenyloxy-2-propyl-oxycarbonylamino-n-hexyl)isocyanate, ginseng (1-propenyloxyethyl-3-) A Isocyanate-based compound having a carbon-carbon double bond-containing group such as a propyleneoxy-2-propyl-oxycarbonylamino-n-hexyl) isocyanate or a stilbene (4-propenyloxy-n-butyl) isocyanate Wait. These photopolymerizable compounds may be used singly or in combination of two or more kinds.

When the ratio of the tensile Young's ratio before and after the radiation hardening is 1.8 or less, the number of carbon-carbon double bonds in one molecule is not particularly limited, and the number of carbon-carbon double bonds in one molecule is preferably 2 to 6. Further, the blending amount of the photopolymerizable compound is not particularly limited, and the adhesive is preferably 10 to 90 parts by mass, more preferably 20 to 70 parts by mass, based on 100 parts by mass of the base polymer. 20 to 60 parts by mass is the best.

The radiation hardening type adhesive can be subjected to a polymerization hardening reaction by radiation irradiation by mixing a photopolymerization initiator in an adhesive. The photopolymerization initiator, for example, a benzoin alkyl ether initiator such as benzoin methyl ether, benzoin ether, benzoin propyl ether, benzoin isopropyl ether or benzoin isobutyl ether; a benzophenone-based initiator such as benzophenone, benzhydrylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone or polyvinylbenzophenone; -hydroxycyclohexyl benzophenone, 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α,α'-dimethylacetophenone, methoxy Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-benzene An aromatic ketone initiator such as benzyl morpholinylpropane-1; an aromatic ketal initiator such as benzyl dimethyl ketal; thioxanthone and 2-chlorothioxanthone , 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-dodecylthioxanthone, 2,4-dichlorothioxanthone, 2,4- Thioxanthone such as dimethyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-diisopropyl thioxanthone An initiator, a benzyl initiator such as benzyl or the like, a benzoin initiator such as benzoin, and an α-acetal compound (2-methyl-2-hydroxypropiophenone, etc.) ), an aromatic chlorosulfonyl compound (2-naphthalene sulfonyl sulfhydryl group, etc.), a photoactive lanthanide compound (1-benzophenone-1, 1-propanedione-2-(o-ethoxyl) Carbonyl), decyl ketone, halogenated ketone, fluorenylphosphine oxide, decylphosphonate, and the like. The photopolymerization initiators may be used singly or in combination of two or more kinds.

The blending amount of the photopolymerization initiator is not particularly limited, and is preferably from 1 to 10 parts by mass, more preferably from 2 to 7 parts by mass, per 100 parts by mass of the base polymer of the adhesive.

Further, in the above adhesive, an isocyanate-based hardener may be blended as needed. Specifically, the isocyanate-based curing agent is a polyvalent isocyanate-based compound such as 2,4-methylphenyl diisocyanate, 2,6-methylphenyl diisocyanate, or 1,3-benzenedimethyl diisocyanate, , 4-phenyldimethyl diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene Diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate, and the like.

The blending amount of the hardener is not particularly limited, and the adhesive is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the base polymer.

The adhesive composition for forming a radiation-curable adhesive may, for example, also contain an adhesive, an anti-aging agent, a filler, a coloring agent, a flame retardant, an antistatic agent, a softening agent, and an ultraviolet ray. Absorbent, anti-oxidation Conventional additives such as a chemical agent, a plasticizer, and a surfactant.

The adhesive layer 3 of the present invention can be formed by a conventional molding method of the adhesive layer 3. For example, a method in which the above-described adhesive composition is applied to a designated surface of a substrate sheet 2, or a method in which an adhesive composition is applied to a separator (for example, a plastic film or sheet coated with a release agent) After the adhesive layer 3 is formed, the adhesive layer 3 is transferred onto the designated surface of the base material sheet 2, and the adhesive layer 3 is formed on the base material sheet 2. The thickness of the adhesive layer 3 is not particularly limited as long as it is higher than the protrusion or the step.

In the first embodiment, the adhesive layer 3 is a radiation-curable adhesive tape 1 for dicing a wafer having a single layer shape, and may have a form in which a plurality of adhesive layers 3 are laminated. When a plurality of layers of the adhesive layer 3 are laminated, the adhesive layer 3 having the surface to which the wafer is bonded at the time of dicing is the radiation-curable adhesive layer 3, and the storage elastic modulus G' before radiation hardening is 1.8 × 10 ⁴ ~ 4.7 × 10 ⁴ Pa, the loss coefficient tan δ before radiation hardening is preferably 0.20 to 0.35.

Further, when the adhesive layer 3 is protected between the required and the actual use, the synthetic resin film used as the separator is usually attached to the side of the adhesive layer 3. A constituent material of the synthetic resin film, for example, a synthetic resin film such as polyethylene, polypropylene, or polyethylene terephthalate or paper. In order to improve the peelability of the self-adhesive layer 3, the surface of the synthetic resin film may be subjected to a release treatment such as polyoxyalkylene treatment, long-chain alkyl treatment, or fluorine treatment. The thickness of the synthetic resin film is usually about 10 to 100 μm, preferably about 25 to 50 μm.

<How to use>

Next, a method of using the adhesive tape 1 for radiation-curable wafer dicing according to the present invention will be described.

The adhesive tape 1 for radiation-curable wafer dicing of the present invention is diced in accordance with a usual method after the mounting step of the semiconductor component attached to the object to be cut, and then moved to a radiation irradiation and crystallization step. A semiconductor component such as a germanium semiconductor, a compound semiconductor, a semiconductor package, glass, or ceramics, and the radiation-curable adhesive tape 1 for wafer-cutting can be suitably used for cutting a semiconductor wafer having a through electrode.

In general, the mounting step is performed by laminating the object to be cut and the radiation-curable wafer-cut adhesive tape 1, and pressing it by a conventional pressing means such as a pressing means of an embossing roll, and simultaneously splicing and cutting Broken and adhesive tape. When the adhesion to the object to be cut is insufficient, a method of heating the object to be cut may be employed.

The cutting step causes the blade to be rotated at a high speed to cut the object to a specified size. A cutting method called a full cut, etc., which cuts into a part of the dicing tape, can be used for cutting.

After the dicing, the adhesive layer 3 is hardened by irradiation of ultraviolet rays to lower the adhesion. By the ultraviolet irradiation, the adhesiveness of the adhesive layer 3 can be lowered by hardening, and peeling can be facilitated. Here, the irradiation amount of the ultraviolet rays is not particularly limited, but is preferably 100 to 1000 mJ/cm ^{2 and more} preferably 200 to 500 mJ/cm ² .

After the ultraviolet irradiation, a crystal removal step is performed. When taking the crystal removal step, Set the expansion step. The crystal extraction method is not particularly limited, and various conventional crystal extraction methods can be employed. For example, each of the cut pieces is protruded from the dicing tape by a tool such as a needle, and the cut piece to be lifted is subjected to crystallization by a crystal picking device.

1‧‧‧Adhesive tape for radiation-hardened wafer cutting

2‧‧‧Substrate film

3‧‧‧Adhesive layer

4‧‧‧ wafer

5‧‧‧Spherical protrusions

[Fig. 1] is a typical cross-sectional view showing the structure of an adhesive tape for radiation-curable wafer dicing according to an embodiment of the present invention.

[Fig. 2] is a typical plan view showing a structure of a wafer cut by an adhesive tape for radiation-curable wafer dicing according to an embodiment of the present invention.

In the following, the invention will be described in more detail on the basis of the examples, but the invention is not limited by the examples.

<Resin composition constituting the adhesive layer>

The following A to H were prepared as a resin composition constituting the adhesive layer.

(Adhesive Composition A)

100 parts by mass of an acrylic polymer (acrylic copolymer (weight average molecular weight: 900,000) obtained from ethyl acrylate: 23 mol%, butyl acrylate: 56 mol%, methoxyethyl acrylate: 21 mol%) 2 parts by mass of a polyisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: CORONATE L) was added as a photopolymerizable product. 30 parts by mass of tetramethylolethane methane tetraacrylate and 2 parts by mass of a photopolymerization initiator (manufactured by BASF Corporation, trade name IRGACURE 184) were mixed and mixed to prepare a radiation curable adhesive composition A.

(Adhesive Composition B)

The adhesive composition B was prepared in the same manner as the adhesive composition A except that the photopolymerizable compound was used in an amount of 60 parts by mass of pentaerythritol triacrylate.

(Adhesive Composition C)

The same as the adhesive composition A except that a copolymer composed of 2-ethylhexyl acrylate, methacrylate, or 2-hydroxyethyl acrylate (weight average molecular weight: 500,000) was used as the acrylic polymer. Modulate the adhesive composition C.

(Adhesive Composition D)

The adhesive composition D was prepared in the same manner as the adhesive composition C except that dipentaerythritol hexaacrylate was used as the photopolymerizable compound and the blending amount was 20 parts by mass.

(Adhesive Composition E)

The adhesive composition E was prepared in the same manner as the adhesive composition D except that the amount of the photopolymerizable compound was 50 parts by mass.

(Adhesive composition F)

The adhesive composition F was prepared in the same manner as the adhesive composition D except that the blending amount of the photopolymerizable compound was 80 parts by mass.

(Adhesive composition G)

100 parts by mass of an acrylic copolymer obtained from 2-ethylhexyl acrylate, methacrylic acid or 2-hydroxyethyl acrylate, and 2 as a compound having a photopolymerizable carbon-carbon double bond and a functional group 2-Methethyloxyethyl isocyanate (manufactured by Showa Denko Co., Ltd., trade name KARENZ MOI) 0.2 parts by mass of the reaction, and the resulting repeating unit of the main chain is bonded with a radiation-hardening carbon-carbon double A polymer (weight average molecular weight: 600,000) of the residue of the acrylic monomer portion of the bond group. 1 part by mass of a polyisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name: CORONATE L), and a photopolymerization initiator (manufactured by BASF Corporation, product) 2 parts by mass of IRGACURE 184) and mixed to prepare a radiation curable adhesive composition G.

(Adhesive Composition H)

The adhesive composition H was prepared in the same manner as the adhesive composition G except that the blending amount of the polyisocyanate compound was 0.5 parts by mass.

(Adhesive Composition I)

In addition to the 2-methylpropenyloxyethyl group reacted with the acrylic copolymer The adhesive composition I was prepared in the same manner as the adhesive composition G except that the amount of the isocyanate blended was 0.6 parts by mass.

<Substrate sheet>

The following J to L were prepared as a substrate sheet.

(Substrate sheet J)

Ethylene-methacrylic acid-(2-methyl-propyl)-Zn++ ionic polymer resin (manufactured by Mitsui‧DuPont PolyChemicals Co., Ltd., trade name High Milan AM7316) at about 200 ° C in a 2-axis kneading machine The film was extruded and formed into a substrate sheet J having a thickness of 100 μm.

(Substrate sheet K)

A film of an ethylene-vinyl acetate copolymer (manufactured by Nippon Unicar Co., Ltd., trade name NUC-3758) was extruded at a temperature of about 200 ° C in a two-axis kneader to prepare a substrate sheet K having a thickness of 100 μm.

(Substrate sheet L)

A polyvinyl chloride sheet (thickness: 100 μm) containing 30 parts by mass of dioctyl phthalate relative to 100 parts by mass of the polyvinyl chloride resin was prepared.

<Production of Adhesive Tape for Radiation Hardening Wafer Cutting>

As shown in Table 1 and Table 2, the thickness after drying is 20 μm. In the formula, the adhesive compositions A to I were applied to the respective substrate sheets J to L to form an adhesive layer, and the radiation-curable wafers of Examples 1, 3 to 9, and Comparative Examples 1 and 2 were produced. Use adhesive tape. Further, the adhesive composition A was applied so as to have a thickness of 25 μm after drying to form an adhesive layer, and the radiation-curable wafer-cut adhesive tape of Example 2 was produced.

<The ratio of Young's rate of adhesive tape>

Using the adhesive tape for radiation-curable wafer dicing of Examples 1 to 9 and Comparative Examples 1 and 2, a test piece was prepared and subjected to a tensile test in accordance with JIS K7127/2/300, and Young's before ultraviolet irradiation was obtained. rate. Further, the substrate sheet side of the adhesive tape test sample was irradiated with ultraviolet rays of 200 mJ/mm ^{2 to} cure the adhesive layer, and the same test was carried out to obtain the Young's ratio after ultraviolet irradiation. The test results of any of the tests are the average of the number of measurements n=5. From the results of this, the ratio of Young's rate (after ultraviolet irradiation) / (before ultraviolet irradiation) was obtained. The results are shown in Tables 1 and 2.

<Viscoseness of Adhesive Layer>

The adhesive composition A~I is applied to the release film in a manner of a thickness of 20 μm after drying to form an adhesive layer, and the adhesive layer is peeled off from the release film to have a total thickness of about 2 mm. Overlap, make test samples. The test sample was perforated into a disk shape having a diameter of 8 mm, and was sandwiched by a parallel blade, and the measurement was carried out under the following conditions using a viscoelasticity measuring apparatus (manufactured by TA Instruments, trade name: ARES). The maximum and minimum values of the storage elastic modulus G' and the loss coefficient from the data obtained The minimum value of tan δ. The results are shown in Tables 1 and 2.

(measurement conditions)

Measuring temperature: 23~80°C

Heating rate: 5 ° C / min

Measuring frequency: 0.15Hz

<Evaluation of Adhesive Tape for Radiation Hardened Wafer Cutting>

The spherical protrusions 5 having a diameter of 10 μm (see Fig. 2) are prepared as Si wafers having a thickness of 30 μm and a thickness of 30 μm. Then, the radiation-curable wafer-cut adhesive tapes of Examples 1 to 8 and Comparative Examples 1 and 2 were bonded to a ring-shaped film.

(burial evaluation)

It is observed whether or not there is a bubble around the spherical protrusion by observing the upper surface of the adhesive tape surface for radiation hardening wafer cutting after self-adhesion. When there is no bubble, it is ◎, when the bubble size is 10 μm or less, it is ○, and when the bubble size is more than 10 μm, it is ×. The results are shown in Tables 1 and 2.

(Evaluation of changes over time)

After the lamination, after placing on the cutting cassette for 1 hour, the same evaluation as the evaluation of the embedding property was carried out. When there is no change after the evaluation of the embedding property, it is ○, and when the expanded width of the bubble size is 5 μm or less, it is Δ, and when the expanded width of the bubble size is larger than 5 μm, it is ×. The results are shown in Tables 1 and 2.

Then, using a dicing apparatus (trade name: DAD-340, manufactured by DISCO Corporation), as shown in Fig. 2, the dicing was carried out under the following conditions so that the size of the wafer 4 was 10 mm square. Further, the spherical projections 5 are formed as shown in Fig. 2 and are not formed on the cutting line.

(cutting conditions)

Blade: "27HECC" manufactured by DISCO Co., Ltd.

Number of blade revolutions: 40,000 rpm

Cutting speed: 50mm/sec

Cutting depth: 25μm

Cutting pattern: cutting down

(Picking crystal evaluation)

The substrate sheet side of the radiation-curable dicing adhesive tape was irradiated with ultraviolet rays of 200 mJ/mm ^{2 to} cure the adhesive layer, and then the individual wafers were molded using a mold-carrying device (manufactured by Canon Machinery Co., Ltd., trade name CAP- 300II) Perform crystal extraction. Any 50 wafers were crystallized under the following conditions A and B, and the number of successfully wafers was calculated. When all 50 wafers were successfully picked up, it was ○, and when 45 to 49 semiconductor wafers were successfully picked up, Δ was removed. The other one is ×, and the crystallinity is evaluated. The results are shown in Tables 1 and 2. Moreover, the failure to take crystal refers to a case where the film cannot be peeled off and there is crack on the wafer to be picked up.

(take crystal condition A)

Number of stitches: 5

Needle spacing: 7.8 × 7.8mm

Bending rate of the front end of the needle: 0.25mm

Needle protrusion amount: 0.30mm

(take crystal condition B)

Number of stitches: 5

Needle spacing: 7.8 × 7.8mm

Bending rate of the front end of the needle: 0.25mm

Needle protrusion amount: 0.40mm

(rupture assessment)

The inside of the wafer taken by the fracture evaluation was evaluated by an optical microscope, and the size of the crack was measured. The distance from the tip end of the wafer to the deepest portion of the crack is ○ when it is 5 μm or less, Δ when it is 6 to 15 μm, and × when it is larger than 15 μm. The results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, in the adhesive tape for radiation-curable wafer-cutting of Examples 1 to 9, the ratio of the Young's ratio after radiation hardening to the Young's ratio before radiation hardening is 1.0 to 1.8, Condition B The crystallinity is preferred. In particular, in Examples 1 to 4, since ethylene acrylate, butyl acrylate, and methoxyethyl acrylate were used as the monomer constituting the matrix polymer, even if the amount of protrusion of the needle was small and the crystallinity was difficult, the condition A was difficult. The crystallinity is also good. In Examples 5 to 9, since ethylene acrylate, butyl acrylate, and methoxyethyl acrylate were not used as the monomer constituting the matrix polymer, Condition A produced a wafer which failed the crystallization, but within the ratio of the allowable range. On the other hand, in the adhesive tape for radiation-curable wafer dicing of Comparative Examples 1 and 2, since the ratio of the Young's ratio after radiation hardening to the Young's ratio before radiation hardening is more than 1.8, the conditions A and B are not good. Grounding is performed.

Further, in the radiation-curable wafer-cut adhesive tapes of Examples 1 to 6, the storage elastic modulus G' of the adhesive layer before radiation curing is 1.8 × 10 ⁴ to 4.7 × 10 ⁴ Pa, due to the radiation of the adhesive layer. The loss coefficient tan δ before hardening is 0.25 to 0.35, and the embedding property, the rupture property, and the change with time after bonding are good. On the other hand, in the adhesive tape for radiation-curable wafer dicing of Example 7, the storage elastic modulus G' of the adhesive layer before radiation curing is 4.7 × 10 ⁴ Pa, and the radiation hardening of Examples 1 to 6 Compared with the adhesive tape for wafer cutting, the embedding property is poor and the cracking property is lowered, but it is within the allowable range. Further, in the adhesive tape for radiation-curable wafer dicing of the eighth embodiment, the storage elastic modulus G' of the adhesive layer before radiation curing is 1.8 × 10 ⁴ , and the radiation-curable wafer for dicing of Examples 1 to 6 is used for dicing Compared to adhesive tape, the cracking is not good, but within the allowable range. Further, in the adhesive tape for radiation-curable wafer dicing of the ninth embodiment, the loss coefficient tan δ of the adhesive layer before radiation hardening is 0.20, which is compared with the radiation-curable wafer-cut adhesive tapes of Examples 1 to 6. After the bonding, the wafer floats due to the change over time, and the cracking property is lowered, but within the allowable range.

1‧‧‧Adhesive tape for radiation-hardened wafer cutting

2‧‧‧Substrate film

3‧‧‧Adhesive layer

Claims (5)

An adhesive tape for radiation-hardening wafer dicing, which is a radiation-curable adhesive tape provided with a radiation-curable adhesive layer on a substrate sheet, which is characterized in that Young's rate after radiation hardening is Young's before radiation hardening The rate of Young's rate after radiation hardening/the Young's rate before radiation hardening is 1.0 to 1.8. The radiation-curable wafer-cut adhesive tape according to claim 1, wherein the storage elastic modulus G' of the adhesive layer before radiation hardening is 1.8 × 10 ⁴ to 4.7 × 10 ⁴ Pa. The radiation-curable wafer-cut adhesive tape according to claim 1 or 2, wherein a loss coefficient tan δ of the adhesive layer before radiation hardening is 0.20 to 0.35. The radiation-curable wafer-cut adhesive tape according to any one of claims 1 to 3, which is used for cutting a semiconductor wafer. The radiation-curable wafer-cut adhesive tape according to claim 4, wherein the semiconductor wafer has a protrusion or a step on a surface to be bonded to the pressure-sensitive adhesive layer.