TWI727244B - Adhesive tape for radiation hardening wafer dicing - Google Patents

Abstract

The present invention provides a radiation hardening type crystal that does not produce adhesive residue during the pick-up step for semiconductor wafers provided with through-electrodes, etc., and can be easily crystallized. Adhesive tape for circular cutting. The radiation-curing adhesive tape (1) for wafer dicing of the present invention is a radiation-curing adhesive tape (1) with a radiation-curing adhesive layer (3) on a substrate sheet (2), which is characterized by radiation curing The ratio of the subsequent tensile modulus to the tensile modulus before radiation hardening is less than 1.0.

Description

Adhesive tape for radiation hardening wafer dicing

The present invention relates to an adhesive tape used to fix a semiconductor wafer or other to-be-cut object when dicing is performed to dicing a semiconductor wafer or the like into a component.

The conventional semiconductor device is manufactured by conducting conductive bonding of a semiconductor chip disposed on a substrate by wire bonding. In recent years, in order to meet the requirements for further miniaturization/thinness/weight reduction of machines, electronic components including semiconductor devices used in these machines are also required. In order to reduce the size of electronic components, for example, a three-dimensional mounting technique in which semiconductor wafers are laminated to achieve high-density mounting has been proposed (for example, refer to Patent Document 1). In addition, as a method of performing three-dimensional mounting technology, for example, it has been proposed to form an electrode (through electrode) penetrating from the surface to the back surface on a wafer, and to laminate the wafer to a mounting wafer called an interposer via the electrode. Semiconductor package structure (for example, refer to Patent Document 2).

It has been discussed to dicing and separating wafers with through-electrodes formed into small element pieces (semiconductor wafers) (dicing step), and when performing the pick-up step (pick-up step) of these semiconductor wafers, the system Adhesive tape for wafer dicing processing with radiation hardening adhesive layer is used.

When using an adhesive tape for wafer dicing with a radiation-curable adhesive layer, the wafer must be adequately held during the dicing step. However, a wafer provided with through-electrodes usually has protrusions of through-electrodes with a height of 3 to tens of μm on one or both sides. Therefore, even if the conventional adhesive tape for dicing processing is attached, the protrusion cannot be conformed to, and the wafer cannot be held in many cases. In addition, this result can cause voids to be generated at the periphery of the protrusion of the through electrode. Generally, in the dicing step, a rotating knife called a blade is used to singulate into individual wafers. When there is a gap between the adhesive layer and the periphery of the protrusion of the through-electrode and cannot be held sufficiently, the impact during cutting causes the wafer to vibrate and cause the blade to collide with the wafer, resulting in wafer defects (cracking) and causing wafer failure. The yield is reduced.

In order to solve the problem in the dicing step, a radiation-curing adhesive tape for wafer dicing has been proposed to make the gel fraction of the adhesive layer and the storage elastic modulus at 10° C. within a specific range (for example, refer to Patent Document 3). The radiation-curing adhesive tape for wafer dicing in Patent Document 3 solves the above-mentioned problems in the dicing step through an adhesive layer having a gel fraction and a storage elastic modulus within a specific range.

However, the radiation-curing adhesive tape for wafer dicing of Patent Document 3 mentioned above, after dicing, when the adhesive layer is hardened by radiation to reduce the adhesive force, the adhesive layer hardens and shrinks, so that the adhesive layer is wrapped Protrusions on the surface of the wafer such as through-electrodes cause the problem that the diced semiconductor wafer cannot be picked up well. The radiation-curable adhesive tape for wafer dicing of Patent Document 3 mentioned above uses an adhesive containing a gas generating agent that generates gas due to irritation. However, in the mechanism that generates gas in the adhesive, since the adhesive becomes brittle, there is a possibility that adhesive chips will adhere to the chip (adhesive residue), which may reduce the yield.

Therefore, in order to solve the problem of the crystal extraction step, there has been proposed a radiation-curing adhesive tape for wafer dicing in which the Young's modulus before and after radiation irradiation is within a specific range (for example, refer to Patent Document 4). The radiation-curing adhesive tape for wafer dicing of Patent Document 4 can solve the above-mentioned problems in the dicing step because the Young's modulus before and after radiation irradiation is within a specific range. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2002-50738 A [Patent Document 2] JP 2005-236245 A [Patent Document 3] JP 2006-202926 A [Patent Document 4] Japanese Patent No. 5294365

[The problem to be solved by the invention]

However, in recent years, some people have developed different shapes and heights of protrusions on the wafer surface such as through electrodes. Even if the radiation-curing adhesive tape for wafer dicing described in Patent Document 4 is used, the adhesive layer still shrinks due to the hardening of the adhesive layer. The adhesive layer covers the protrusions on the surface of the wafer, and there is a problem that the diced semiconductor wafer cannot be picked up well.

Therefore, the present invention is to provide a radiation hardening type wafer dicing adhesive tape for semiconductor wafers provided with through-electrodes, etc., which does not produce adhesive residue during the crystallization step and can easily perform the crystallization. purpose. [Means to solve the problem]

In order to solve the above-mentioned problems, the radiation-curing adhesive tape for wafer dicing of the present invention is a radiation-curing adhesive tape with a radiation-curing adhesive layer on a substrate sheet. The ratio of the tensile modulus of elasticity before hardening does not reach 1.0.

In the above-mentioned radiation-curing adhesive tape for wafer dicing, it is preferable that the storage elastic modulus G'of the adhesive layer before radiation curing measured at 23°C is 1.8×10 ^{4 in the entire range of the measurement frequency of 0.1 to 10 Hz.} Pa.

Furthermore, in the above-mentioned radiation-curable adhesive tape for wafer dicing, it is preferable that the loss coefficient tanδ of the adhesive layer before radiation curing is 0.25 or more.

In addition, the above-mentioned adhesive tape for radiation hardening type wafer dicing can be suitably used when dicing semiconductor wafers.

In addition, the above-mentioned radiation-curable adhesive tape for wafer dicing can be suitably used when the semiconductor wafer has protrusions or steps on the surface to be bonded to the adhesive layer. [Effects of Invention]

According to the present invention, chip breakage in the dicing step can be reduced, and for semiconductor wafers provided with through-electrodes, no adhesive residue is generated during the crystallization step, and the crystallization can be easily performed.

[The form of implementing the invention]

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

In the radiation-curing adhesive tape 1 for wafer dicing according to the embodiment of the present invention, at least one adhesive layer 3 is formed on at least one surface of the base sheet 2. 1 is a schematic cross-sectional view showing a preferred embodiment of the radiation-curing adhesive tape 1 for wafer dicing of the present invention. The radiation-curing adhesive tape 1 for wafer dicing has a base sheet 2 formed on the base sheet 2 Adhesive layer 3.

The radiation-curing adhesive tape 1 for wafer dicing according to the embodiment of the present invention has the ratio of the tensile elastic modulus after radiation curing to the tensile elastic modulus before radiation curing (the ratio of tensile elastic modulus after radiation curing/before radiation curing) Tensile modulus of elasticity) does not reach 1.0.

When bonding a wafer with bumps or steps on the surface where the adhesive layer 3 is attached to the radiation-curing adhesive tape 1 for wafer dicing, use bumps or steps when attaching the wafer with bumps or steps to the radiation-curing adhesive tape 1 for wafer dicing. It is better to be almost completely embedded in the adhesive layer 3. When there is a gap between the bump or the step and the adhesive tape 1 for radiation-curing wafer dicing, the wafer is greatly vibrated due to the vibration of the rotating knife (blade) during the dicing step, causing contact with the blade or adjacent wafers , And the problem of chip cracking occurs.

In addition, when the bump or step is almost completely embedded in the adhesive layer 3, the influence of the vibration of the rotating knife can be reduced. However, when the radiation-curing adhesive is used in the adhesive constituting the adhesive layer 3, the adhesive layer 3 It is hardened in the state of being in close contact with the bumps or the steps, and the adhesive layer 3 covers the bumps or the steps during the crystal taking step, which causes the problem that the crystal cannot be taken.

Herein, 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 an initiator that generates free radicals when exposed to radiation. By irradiating radiation, the initiator is activated and the carbon-carbon unsaturated bond at the end is activated by the generated free radicals, and the compounds (a) are successively bonded, and the compounds (a) are cross-linked with each other.

Before cross-linking is formed, since the plurality of compounds (a) dispersed in the adhesive are aggregated and bonded by cross-linking, the adhesive becomes harder after cross-linking than before cross-linking. When the cross-linking reaction is caused in the state of being in close contact with the bumps or the steps, the hardened adhesive covers the bumps or the steps and prevents smooth peeling. Especially in a wafer with through-electrodes, when bumps are formed to penetrate the inside of the wafer, the strength of the wafer is significantly weakened and peeling is prevented, which may easily cause the chip to crack. When the adhesive is hardened to cover bumps or steps, it can be suppressed by adjusting the degree of hardening of the adhesive.

As an index indicating the degree of curing of the adhesive, there is the tensile elastic modulus of the radiation-curable adhesive tape 1 for wafer dicing. The ratio of the tensile elastic modulus before radiation curing to the tensile elastic modulus after curing (tensile elastic modulus after radiation curing/tensile elastic modulus before curing) is closer to 1, which means the change in hardness before self-crosslinking is formed. Smaller. The radiation-curable adhesive layer 3 is as described above, and because the curing reaction occurs by radiation irradiation, the above-mentioned ratio is usually greater than one.

In contrast, the radiation-curing adhesive tape 1 for wafer dicing according to the embodiment of the present invention has the ratio of the tensile elastic modulus after radiation curing to the tensile elastic modulus before radiation curing (the tensile elastic modulus after radiation curing/ The tensile elastic modulus before radiation hardening) did not reach 1.0. When the ratio is less than 1.0, the occurrence of covered bumps or step differences is rare, and the crystal can be easily taken. If it is 1.0 or more, the bumps or the step size will cover the bumps or the step, and the stress applied to the wafer during the push-up step in the crystal taking step will increase, and the crystal cannot be taken or the chip will be damaged.

The degree of hardening of the adhesive depends on the content or type of compound (a); if the above ratio is less than 1.0, it is advisable to reduce the content of compound (a). This is because the intermolecular entanglement between the compound (a) and other constituents that are dispersedly produced before the formation of the crosslinking reaction is eliminated by the aggregation of the compound (a) during the crosslinking reaction.

In addition, the tensile modulus here is a value obtained based on JIS K 7127:1999. In addition, the base sheet 2 is generally thicker than the adhesive layer 3 and has higher rigidity. However, the ratio of the tensile elastic modulus of the radiation-curing adhesive tape 1 for wafer dicing can be compared with that of only the adhesive The tensile elasticity of layer 3.

Here, the radiation dose is not particularly limited. For example, in the case of ultraviolet rays, 100~1000 mJ/cm ^{2 is} preferred, and 200~500 mJ/cm ^{2 is more} preferred.

In order to prevent chipping of the semiconductor chip, it is preferable that the storage elastic modulus G'of the adhesive layer 3 before radiation curing measured at 23°C is 1.8×10 ⁴ ～4.0×10 in the whole range of the measuring frequency 0.1～10Hz ⁴ Pa. When G'is less than 1.8×10 ⁴ Pa, the adhesive layer 3 can be fully adhered to the bumps or steps. However, the adhesive layer 3 is too soft to suppress the vibration generated by the rotating knife during the cutting step, and chipping occurs. Situation. In addition, when it exceeds 4.0×10 ⁴ Pa, the adhesive layer 3 cannot be sufficiently adhered to the bumps or the steps to form voids, and eventually, the rotating blade vibration in the cutting step may cause chipping.

In addition, in order to maintain the state that the adhesive layer 3 is sufficiently close to the bump or step, the loss coefficient tanδ of the adhesive layer 3 before radiation curing is preferably 0.25 or more. The loss coefficient tanδ is expressed as the ratio of the storage elastic modulus G'to the loss elastic modulus G" (G"/G'). When the tanδ is small, even if the adhesive layer 3 is sufficiently close to the bump or step, it is difficult to maintain the close state due to the large mutual repulsion ability. When the loss coefficient tanδ of the adhesive layer 3 is less than 0.25, the state of close contact cannot be maintained, a gap is generated between the wafer and the adhesive tape, and the chip may be chipped and deteriorated due to the above mechanism.

Hereinafter, each component of the radiation-curing adhesive tape 1 for wafer dicing of this embodiment will be described in detail.

(Substrate sheet 2) The resin constituting the substrate sheet 2 is not particularly limited, and a resin that can be formed into a sheet shape 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-diene can also be used 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, polyamide, ion Polymers, nitrile rubber, butyl rubber, styrene isoprene rubber, styrene butadiene rubber, natural rubber and its hydrogenated or modified products, etc. These resins can be used alone or in a mixture of two or more types, and they can also be composed of two or more layers.

The thickness of the substrate sheet 2 is not particularly limited. When it is too thin, it is not easy to handle, and when it is too thick, it is difficult to transmit the stress of the pushing tool during the crystal taking step. Therefore, 50~150μm is preferred, and 70~100μm is more preferred.

In order to improve the adhesiveness, the surface of the base sheet 2 to which the adhesive layer 3 is connected may be corona treated, or a primer layer or the like may be treated.

(Adhesive layer 3) For the adhesive composition constituting the adhesive layer 3, for example, it is preferable to use the one described in Japanese Patent Application Laid-Open No. 7-135189, etc. However, it is not limited by these and can be blended with a rubber-based or acrylic-based matrix polymer A compound having at least two radiation polymerizable carbon-carbon double bonds in the molecule (hereinafter referred to as a photopolymerizable compound) and a photopolymerization initiator, or an acrylic matrix polymer having carbon-carbon addition Compounds with double bonds.

The method of introducing a carbon-carbon double bond into an acrylic polymer is not particularly limited. For example, by copolymerizing a monomer having a functional group as a copolymerizable monomer to prepare an acrylic polymer containing a functional group , A compound having a functional group that can react with a functional group in a functional group-containing acrylic polymer and a carbon-carbon double bond, while maintaining the radiation curability (radiation polymerizability) of the carbon-carbon double bond, A method for preparing an acrylic polymer having a carbon-carbon double bond in the molecule by performing a condensation reaction or an addition reaction with a functional group-containing acrylic polymer.

The above-mentioned rubber-based or acrylic-based matrix polymer uses natural rubber, various synthetic rubbers and other rubber-based polymers, or poly(meth)acrylate, (meth)acrylate, (meth)acrylate, and Acrylic polymers such as copolymers of other unsaturated monomers that can be copolymerized with them.

Examples of the photopolymerizable compound include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanedi Alcohol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerol di(meth)acrylate, etc. (meth)acrylic acid and polyols Ester; ester acrylate oligomer; 2-propenyl-di-3-butenyl cyanate and other cyanate ester compounds having a carbon-carbon double bond-containing group; Ethyl) isocyanate, ginseng (2-methacryloyloxyethyl) isocyanate, 2-hydroxyethyl bis(2-acryloyloxyethyl) isocyanate, bis(2-acryloyloxyethyl) 2-[(5-propenyloxyhexyl)-oxy]ethyl isocyanate, ginseng (1,3-dipropenyloxy-2-propyl-oxycarbonylamino-n-hexyl) isocyanate, ginseng (1 -Acryloyloxyethyl-3-methacryloyloxy-2-propyl-oxycarbonylamino-n-hexyl) isocyanate, ginseng (4-acryloyloxy-n-butyl) isocyanate, etc. Isocyanate compounds containing carbon-carbon double bond groups, etc. These photopolymerizable compounds can be used alone or in combination of two or more kinds.

As long as the ratio of tensile modulus before and after radiation hardening is less than 1.0, the number of carbon-carbon double bonds in a molecule is not particularly limited, and the number of carbon-carbon double bonds in a single molecule is preferably 2-6. In addition, the blending amount is not particularly limited, and it is preferably 10 to 90 parts by mass, and more preferably 10 to 40 parts by mass relative to 100 parts by mass of the aforementioned base polymer of the adhesive.

Radiation-curable adhesives can be polymerized and cured by mixing a photopolymerization initiator in the adhesive and irradiating it with radiation. As the photopolymerization initiator, for example, benzyl ether, benzyl ethyl ether, benzyl propyl ether, benzyl isopropyl ether, benzyl isobutyl ether and other benzyl ether-based Starter; Benzophenone-based starter such as benzophenone, benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, etc. ; Α-hydroxycyclohexyl phenone, 4-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, methyl Oxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio) -Phenyl]-2-morpholinopropane-1 and other aromatic ketone-based initiators; benzyl dimethyl ketal and other aromatic ketal-based initiators; thioxanthone, 2-chlorothioxanthone , 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-dodecylthioxanthone, 2,4-dichlorothioxanthone, 2,4- Thioxanthone-based initiators such as dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and diphenylethylenedione such as diphenylethylenedione Ketone-based initiators, benzyl-based initiators such as benzyl, as well as α-keto alcohol-based compounds (2-methyl-2-hydroxypropiophenone, etc.), aromatic chlorinated sulfonyl-based compounds (2 -Naphthalene chlorinated sulfonyl, etc.), photoactive oxime compounds (1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime, etc.), camphor ketone, halogenated ketone, acetone Phosphine oxide, phosphonic acid ester, etc. The photopolymerization initiator can be used alone or in combination of two or more kinds.

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

In addition, an isocyanate-based hardener may be blended in the above-mentioned adhesive as required. Specifically, the isocyanate-based curing agent uses a polyvalent isocyanate-based compound, such as 2,4-tolylphenyl diisocyanate, 2,6-tolylphenyl diisocyanate, 1,3-xylylene diisocyanate, 1 ,4-Benzyldimethyl 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, etc.

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

The adhesive composition used to form radiation-curable adhesives may also contain, if necessary, tackifiers, anti-aging agents, fillers, colorants, flame retardants, antistatic agents, softeners, ultraviolet absorbers, Antioxidants, plasticizers, surfactants and other conventional additives.

The adhesive layer 3 of the present invention can be formed by a conventional method for forming the adhesive layer 3. For example, it can be formed by coating the above-mentioned adhesive composition on the designated surface of the substrate sheet 2, or by coating the adhesive composition on a separator (such as a plastic film coated with a release agent). Or a sheet, etc.) after the adhesive layer 3 is formed, then the adhesive layer 3 is transferred to the designated surface of the base sheet 2 to form the adhesive layer 3 on the base sheet 2. The thickness of the adhesive layer 3 is not particularly limited as long as it is higher than the bump or the step.

In addition, FIG. 1 shows a radiation-curing adhesive tape 1 for wafer dicing in which the adhesive layer 3 has a single-layer form, and may have a form in which a plurality of layers of adhesive layers 3 are laminated. When a plurality of adhesive layers 3 are laminated, the adhesive layer 3 having the surface to be attached to the wafer during dicing is the radiation-curing adhesive layer 3, and the storage elastic modulus measured at 23°C before radiation curing ^{The number G'is 1.8×10 4} to 4.0×10 ⁴ Pa in the entire range of the measurement frequency of 0.1 to 10 Hz, and the loss coefficient tan δ before radiation hardening is preferably 0.25 or more.

In addition, as needed, between actual use, in order to protect the adhesive layer 3, a synthetic resin film used as a separator can usually be attached to the adhesive layer 3 side. As a constituent material of the synthetic resin film, synthetic resin films such as polyethylene, polypropylene, polyethylene terephthalate, and paper, etc., can be cited. In order to improve the releasability of the self-adhesive layer 3, the surface of the synthetic resin film may also be subjected to peeling treatments such as polysiloxane treatment, long-chain alkyl treatment, fluorine treatment, etc., as required. The thickness of the synthetic resin film is usually about 10-100 μm, preferably about 25-50 μm.

＜How to use＞ Next, the method of using the radiation-curing adhesive tape 1 for wafer dicing of the present invention will be explained.

The radiation-curing adhesive tape 1 for wafer dicing of the present invention is diced in accordance with the usual method after the mounting step of the semiconductor component attached to the cut object, and then moves to the radiation irradiation and crystal picking step. Examples of semiconductor components include silicon semiconductors, compound semiconductors, semiconductor packages, glass, ceramics, and the like. The radiation-curable wafer dicing adhesive tape 1 can be suitably used when dicing semiconductor wafers with through electrodes.

Usually, the mounting step is to overlap the cut object and the radiation-curing adhesive tape 1 for wafer dicing, and press it by a conventional pressing means such as pressing means using a pressing roller, and at the same time the sticking is cut. Objects and adhesive tape. When the adhesion with the cut object is insufficient, the method of heating the cut object can also be used.

The cutting step is to rotate the blade at a high speed to cut the cut object into a specified size. When cutting, it is possible to use a cutting method called full cut, etc., until the tape is cut into a part.

After cutting, the adhesive layer 3 is cured by irradiating ultraviolet rays to reduce the adhesiveness. By ultraviolet irradiation, the adhesiveness of the adhesive layer 3 can be reduced by curing, and it can be peeled off more easily. Here, the irradiation amount of ultraviolet rays is not particularly limited, and is preferably 100 to 1000 mJ/cm ^{2 and more} preferably 200 to 500 mJ/cm ² .

After ultraviolet irradiation, a crystal-taking step is performed. During the crystal taking step, an expansion step can be set. The crystal taking method is not particularly limited, and various conventional crystal taking methods can be used. For example, a method in which each cut piece is pushed up from the dicing tape with a tool such as a needle, and the cut piece that has been pushed up is picked up by a crystal picking device.

In the following, the present invention is explained in more detail based on examples, but the present invention is not limited by these examples.

＜Resin composition constituting the adhesive layer＞ As the resin composition constituting the adhesive layer, the following A to F were prepared.

(Adhesive composition A) With respect to 100 parts by mass of acrylic polymer (ethyl acrylate: 23 mol%, butyl acrylate: 56 mol%, and methoxyethyl acrylate: 21 mol%) 100 parts by mass, Add 2 parts by mass of polyisocyanate compound (manufactured by Japan Polyurethane Industry Co., Ltd., trade name CORONATE L), 20 parts by mass of tetramethylolmethane tetraacrylate as a photopolymerizable compound, and start of photopolymerization 2 parts by mass of an agent (manufactured by Ciba Geigy, Japan, trade name IRGACURE 184) were 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 30 parts by mass of pentaerythritol triacrylate was used as the photopolymerizable compound.

(Adhesive composition C) Except that the acrylic polymer uses a copolymer of 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate (weight average molecular weight 500,000), the adhesive is prepared in the same way as the adhesive composition A 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 18 parts by mass.

(Adhesive composition E) 100 parts by mass of an acrylic copolymer composed of 2-ethylhexyl acrylate, methacrylic acid, and 2-hydroxyethyl acrylate, and 2- that is a compound having a photopolymerizable carbon-carbon double bond and a functional group 0.15 parts by mass of methacryloxyethyl isocyanate (manufactured by Showa Denko Co., Ltd., trade name KARENZ MOI) was reacted to prepare a polymer having residues of acrylic monomers bonded to repeating units of the main chain (Weight average molecular weight 600,000), the acrylic monomer part has a radical containing a radiation-curable carbon-carbon double bond. With respect to 100 parts by mass of the above polymer, 1 part by mass of a polyisocyanate compound (manufactured by Japan Polyurethane Industry Co., Ltd., trade name CORONATE L), and a photopolymerization initiator (manufactured by Ciba Geigy, Japan, product Name IRGACURE 184) 0.5 parts by mass and mixed to prepare radiation-curable adhesive composition E.

(Adhesive composition F) The adhesive composition F was prepared in the same manner as the adhesive composition E except that the blending amount of the polyisocyanate compound was 0.25 parts by mass.

(Adhesive composition J) The adhesive composition J was prepared in the same manner as the adhesive composition F except that the blending amount of 2-methacryloxyethyl isocyanate was 0.1 parts by mass.

＜Substrate sheet＞ Prepare the following G and H as substrate sheets.

(Substrate sheet G) The ethylene-methacrylic acid-Zn++ ionic polymer resin (manufactured by Mitsui‧DuPont PolyChemicals Co., Ltd., trade name High Milan 1706) was extruded into a film with a biaxial kneader at about 200°C to obtain a thickness of 100μm. Substrate sheet G.

(Substrate sheet H) The ethylene-vinyl acetate copolymer (manufactured by Nippon Unicar Co., Ltd., trade name NUC-3758) was subjected to film extrusion molding using a biaxial kneader at about 200°C to prepare a substrate sheet H having a thickness of 100 μm.

＜Production of radiation-curing adhesive tape for wafer dicing＞ As shown in Table 1, the above-mentioned adhesive composition F was applied to each of the substrate sheets G and H to form an adhesive layer in such a way that the thickness after each drying was 25 μm, and the examples 1, 3~ 7. Adhesive tapes for radiation hardening wafer dicing of Comparative Examples 1 and 2. Furthermore, the adhesive composition A was applied to a thickness of 30 μm after drying to form an adhesive layer, and the radiation-curable adhesive tape for wafer dicing of Example 2 was prepared.

<Tensile elastic modulus ratio of adhesive tape> Using the radiation-curable wafer dicing adhesive tapes of Examples 1 to 7 and Comparative Examples 1 and 2, in accordance with JIS K7127/2/300, a test piece was produced and a tensile test was performed. Calculate the tensile elastic modulus before UV irradiation. ^{Furthermore, after irradiating 200 mJ/mm 2} of ultraviolet rays from the substrate sheet side of the adhesive tape test sample to harden the adhesive layer, the same test was performed to calculate the tensile elastic modulus after ultraviolet ray irradiation. The test result of any test is the average value of the measured number n=5. From these results, the ratio of tensile modulus of elasticity ((after ultraviolet irradiation)/(before ultraviolet irradiation)) was calculated. The results are shown in Table 1.

＜Viscoelasticity of the adhesive layer＞ Apply the adhesive composition A to F on the release film in such a way that the thickness after drying each is 25μm. After the adhesive layer is formed, the adhesive layer is peeled from the release film to a total thickness of about 2mm. Overlap, and make a test sample. This test sample was punched into a disk shape with a diameter of 8 mm, sandwiched between parallel plates, and measured under the following conditions using a viscoelasticity measuring device (manufactured by TA Instruments, trade name ARES). The obtained data records store the maximum and minimum values of the elastic modulus G'and the minimum value of the loss coefficient tanδ. The results are shown in Table 1. (Measurement conditions) Measuring frequency: 0.1～10Hz Set temperature: 23℃

<Evaluation of Adhesive Tapes for Radiation Curing Wafer Dicing> Spherical bumps 5 with a diameter of 15 μm (refer to FIG. 2) are prepared to form an 8-inch Si wafer with a thickness of 30 μm formed at intervals of 100 μm. Then, the adhesive tapes for radiation hardening wafer dicing of Examples 1 to 7 and Comparative Examples 1 and 2 were attached to the ring frame at the same time.

(Evaluation of Embeddedness) Visually observe whether there are bubbles around the spherical bumps from above the surface of the adhesive tape for radiation-curing wafer dicing immediately after bonding. When there is no bubbles, it is rated as good ○, when the bubble size is less than 10 μm, it is rated as acceptable product, and when the bubble size is greater than 10 μm, it is rated as defective product. The results are shown in Table 1.

(Assessment of changes over time after fitting) After lamination, it is placed on the cutting cassette for 1 hour, and then the same evaluation as the evaluation of embedding is carried out. If there is no change after the embedding evaluation, it is rated as good ○, when the expansion of the bubble size is less than 5 μm, it is rated as the allowable product, and when the expansion of the bubble size is greater than 5 μm, it is rated as defective. The results are shown in Table 1.

Thereafter, using a dicing device (manufactured by DISCO Co., Ltd., trade name DAD-340), as shown in FIG. 2, dicing was performed under the following conditions so that the size of the wafer 4 was 10 mm square. Moreover, the spherical bump 5 is formed in FIG. 2 and is not formed on the cutting line. (Cutting conditions) Blade: "27HECC" manufactured by DISCO Co., Ltd. Blade rotation number: 40000rpm Cutting speed: 50mm/sec Cutting depth: 25μm Cutting mode: cutting downward

^{(Evaluation of crystal picking) After irradiating 200mJ/mm 2} of ultraviolet rays from the base sheet side of the adhesive tape for radiation-curing wafer dicing to harden the adhesive layer, the singulated wafer is used with a mold picking device (Canon Machinery Co., Ltd Company system, trade name CAP-300II) to take crystals. Pick up any 50 wafers under the following conditions and count the number of wafers that have successfully picked up. When all 50 wafers are successfully picked up, they are rated as good ○, and the others are rated as defective products × to evaluate the crystal picking properties. The results are shown in Table 1. In addition, the failure of picking crystal refers to the situation when it cannot be peeled off and there is a crack on the picked up wafer. (Conditions for taking crystals) Number of needles: Interval between 5 needles: 7.8×7.8mm Curvature of needle tip: 0.25mm Needle pushing amount: 0.30mm

(Fragmentation assessment) The backside of 30 wafers taken for evaluation of chipping was observed with an optical microscope, and the size of chipping was measured. When the distance from the tip of the chip to the deepest part of the chip is less than 5μm, it is rated as good ○, when it is 6~15μm, it is rated as allowable product, and when it is greater than 15μm, it is rated as defective product. The results are shown in Table 1.

As shown in Table 1, the radiation-curing adhesive tapes for wafer dicing of Examples 1 to 7 have crystal properties because the ratio of the tensile elastic modulus after radiation curing to the tensile elastic modulus before radiation curing is less than 1.0. good. In contrast, the radiation-curing adhesive tapes for wafer dicing of Comparative Examples 1 and 2 have a ratio of the tensile modulus after radiation curing to the Young's modulus before radiation curing exceeding 1.0, and therefore, the crystallization cannot be performed well. .

Furthermore, the radiation-curing adhesive tapes for wafer dicing of Examples 1 to 3 have a storage elastic modulus G'of the adhesive layer measured at 23°C before radiation curing in the entire range of the measurement frequency of 0.1 to 10 Hz. 1.8×10 ⁴ ～4.0×10 ⁴ Pa, and the loss coefficient tanδ of the adhesive layer before radiation hardening is 0.25 or more, so the embedding property, crystal taking property, and change over time after bonding are all good. In contrast, the radiation-curing adhesive tape for wafer dicing of Example 4 has a storage elastic modulus G'of the adhesive layer before radiation curing exceeds 4.0×10 ⁴ Pa, which is similar to Examples 1 to 3 and Examples Compared with the radiation-curing adhesive tape for wafer dicing of 5, the embedding property is inferior and the crystallinity deteriorates, but it is in the allowable range. In addition, the radiation-curing adhesive tapes for wafer dicing of Examples 6 and 7 have a storage elastic modulus G'of less than 1.8×10 ⁴ for the adhesive layer before radiation curing, which is the same as the radiation-curing adhesive tapes of Examples 1 to 5 Adhesive tapes for wafer dicing are inferior in crystal pick-up, but they are within an allowable range. In addition, the radiation-curing adhesive tape for wafer dicing of Examples 5 to 7 has a loss coefficient tanδ of less than 0.25 before radiation curing of the adhesive layer, which is comparable to the radiation-curing adhesive tape for wafer dicing of Examples 1 to 4 Compared with the case where the wafer loosens due to changes in time after bonding, the crystallinity deteriorates, but it is within an allowable range.

1‧‧‧Adhesive tape for radiation hardening wafer dicing 2‧‧‧Substrate sheet 3‧‧‧Adhesive layer 4‧‧‧Chip 5‧‧‧Spherical bump

Fig. 1 is a cross-sectional view schematically showing the structure of a radiation-curable adhesive tape for wafer dicing according to an embodiment of the present invention. 2 is a plan view schematically showing the structure of a wafer cut using the radiation-curing adhesive tape for wafer dicing according to an embodiment of the present invention.

1‧‧‧Adhesive tape for radiation hardening wafer dicing

2‧‧‧Substrate sheet

3‧‧‧Adhesive layer

Claims (4)

A radiation-curing adhesive tape for wafer dicing, which is a radiation-curing adhesive tape provided with a radiation-curing adhesive layer on a substrate sheet, characterized in that: the aforementioned radiation-curing adhesive layer is composed of an adhesive The adhesive composition is made by blending a compound with a radiation polymerizable carbon-carbon double bond in the molecule of the matrix polymer and a photopolymerization initiator. The tensile elastic modulus is measured in accordance with JIS K 7127, and it is cured by radiation. The ratio of the latter tensile modulus to the tensile modulus before radiation curing exceeds 0 and does not reach 1.0. The aforementioned compound with radiation polymerizable carbon-carbon double bonds has a number of carbon-carbon double bonds in one molecule of 2~ 6 and the blending amount is 10~90 parts by mass relative to 100 parts by mass of the aforementioned base polymer. The storage elastic modulus G'of the aforementioned adhesive layer before radiation curing measured at 23°C is measured at a frequency of 0.1~10Hz The entire range is 1.8×10 ⁴ ~4.0×10 ⁴ Pa. Such as the radiation-curing adhesive tape for wafer dicing of claim 1, wherein the loss coefficient tanδ of the adhesive layer before radiation curing is 0.25 or more. For example, the adhesive tape for radiation hardening wafer dicing of claim 1 or claim 2, which is used when dicing semiconductor wafers. According to claim 3, the radiation-curing adhesive tape for wafer dicing, wherein the semiconductor wafer has protrusions or steps on the surface attached to the adhesive layer.

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