JP5294365B1 - Radiation curable adhesive tape for dicing - Google Patents

Abstract

Disclosed is a radiation-curing dicing pressure-sensitive adhesive tape that can be easily picked up on a semiconductor chip or the like provided with a through electrode without causing adhesive residue in a pick-up process.
A radiation curable dicing pressure-sensitive adhesive tape 1 of the present invention is a radiation curable pressure-sensitive adhesive tape 1 in which a radiation curable pressure-sensitive adhesive layer 3 is provided on a base sheet 2 and is a Young after radiation curing. The ratio of the ratio to the Young's modulus before radiation curing is 1.8 or less.
[Selection] Figure 1

Description

  The present invention relates to an adhesive tape used for fixing a workpiece such as a semiconductor wafer when the semiconductor wafer or the like is cut and separated (diced) in order to make an element into small pieces.

  Conventional semiconductor devices have been manufactured by conductively connecting semiconductor chips installed on a substrate by wire bonding. In recent years, in response to demands for further downsizing, thinning, and weight reduction of devices, similar requirements have been made for electronic components including semiconductor devices used in these devices. In order to reduce the size of electronic components, for example, a three-dimensional mounting technique that realizes high-density mounting by stacking semiconductor chips has been proposed (see, for example, Patent Document 1). Further, as a method for performing a three-dimensional mounting technique, for example, a semiconductor package structure in which an electrode (penetrating electrode) penetrating a chip is formed and a mounting chip called an interposer is stacked via the electrode is proposed ( For example, see Patent Document 2).

  The wafer with through electrodes formed is cut and separated into element pieces (semiconductor chips) (dicing process), and the process for picking up these semiconductor chips (pickup process) has a radiation-curing adhesive layer for wafer dicing processing. The use of tape is being considered.

  When using an adhesive tape for wafer dicing having a radiation curable adhesive layer, the wafer must be sufficiently retained in the dicing process. However, in a wafer provided with through electrodes, there are usually protrusions of through electrodes having a height of 3 to several tens of μm on one or both surfaces. For this reason, even if the conventional adhesive tape for dicing processing is bonded, it is often impossible to follow the protrusions and hold the wafer. As a result, a gap may be generated around the protrusion of the through electrode. Usually, in a dicing process, it is divided into chips by a rotary blade called a blade. If there is a gap between the adhesive layer and the periphery of the protrusion of the through-electrode, the chip vibrates due to impact during cutting, causing a collision between the blade and the chip, and chipping (chipping) Occurs to reduce the yield of chips.

  In order to eliminate problems in the dicing process, a radiation-curing dicing pressure-sensitive adhesive tape in which the gel fraction of the pressure-sensitive adhesive layer and the storage elastic modulus at 10 ° C. are within a specific range has been proposed (for example, see Patent Document 3). In the radiation curing type dicing pressure-sensitive adhesive tape disclosed in Patent Document 3, the above-mentioned problem in the dicing step is eliminated by having the pressure-sensitive adhesive layer having a gel fraction and a storage elastic modulus within a specific range.

JP 2002-50738 A JP 2005-236245 A JP 2006-202926 A

  However, in the radiation curing type dicing pressure-sensitive adhesive tape of Patent Document 3, the pressure-sensitive adhesive layer is cured and contracted when the pressure-sensitive adhesive force is reduced by irradiating the pressure-sensitive adhesive layer with radiation after curing. For this reason, there is a problem that the adhesive layer bites into the protrusions on the wafer surface such as the through electrodes, and the diced semiconductor chip cannot be picked up well. In the radiation curing type dicing pressure-sensitive adhesive tape of Patent Document 3, a pressure-sensitive adhesive containing a gas generating agent that generates gas by stimulation is used. However, in the mechanism in which gas is generated in the pressure-sensitive adhesive, since the pressure-sensitive adhesive becomes brittle, adhesion of pressure-sensitive adhesive waste (glue residue) to the chip occurs, which may reduce the yield.

  Accordingly, an object of the present invention is to provide a radiation curable dicing adhesive tape that can be easily picked up without causing adhesive residue in a pick-up process even for a semiconductor chip or the like provided with a through electrode. And

  In order to solve the above problems, a radiation curable dicing adhesive tape according to the present invention is a radiation curable adhesive tape in which a radiation curable adhesive layer is provided on a base sheet, and is a Young after radiation curing. The ratio of the ratio to the Young's modulus before radiation curing is 1.8 or less.

The radiation curable dicing adhesive tape preferably has a storage elastic modulus G ′ of 2.0 × 10 ^{4 to} 4.5 × 10 ⁴ Pa before radiation curing of the pressure-sensitive adhesive layer.

  The radiation curable dicing pressure-sensitive adhesive tape preferably has a loss coefficient tan δ before radiation curing of the pressure-sensitive adhesive layer of 0.25 or more.

  Moreover, the said radiation-curing-type dicing adhesive tape can be used conveniently when dicing a semiconductor wafer.

  The radiation-curing dicing pressure-sensitive adhesive tape can be suitably used when the semiconductor wafer has protrusions or steps on the surface bonded to the pressure-sensitive adhesive layer.

  According to the present invention, chipping in a dicing process can be reduced, and even a semiconductor chip provided with a through electrode can be easily picked up without generating adhesive residue in the pick-up process.

It is sectional drawing which shows typically the structure of the adhesive tape for radiation hardening type dicing which concerns on embodiment of this invention. It is a top view which shows typically the structure of the chip | tip cut | disconnected using the radiation curing type dicing adhesive tape which concerns on the Example of this invention.

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

  In the radiation curing type dicing pressure-sensitive adhesive tape 1 according to the embodiment of the present invention, at least one pressure-sensitive adhesive layer 3 is formed on at least one side of the base material sheet 2. FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the radiation curable dicing pressure-sensitive adhesive tape 1 of the present invention. The radiation curable dicing pressure-sensitive adhesive tape 1 has a base sheet 2, and the base sheet 2 An adhesive layer 3 is formed on the top.

  The radiation curing type dicing pressure-sensitive adhesive tape 1 according to the embodiment of the present invention has a ratio of Young's modulus after radiation curing to Young's modulus before radiation curing (Young's modulus after radiation curing / Young's modulus before radiation curing) of 1. 8 or less.

  When a wafer having a bump or a step is bonded to the surface of the radiation curable dicing pressure-sensitive adhesive tape 1 to which the pressure-sensitive adhesive layer 3 is bonded, the bump or the step is the pressure-sensitive adhesive layer. 3 is preferably almost completely buried. If there is a gap between the bump or step and the radiation curable dicing adhesive tape 1, the chip vibrates greatly due to the vibration of the rotary blade (blade) in the dicing process, and contact with the blade or adjacent chip may occur. Will occur and chipping will occur.

  On the other hand, when bumps or steps are almost completely embedded in the pressure-sensitive adhesive layer 3, the influence of vibration by the rotary blade can be reduced, but when a radiation curable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3. Since the pressure-sensitive adhesive layer 3 is cured in a state of being in close contact with the bump or the step, the pressure-sensitive adhesive layer 3 may be caught by the bump or the step during the pickup process, which may cause a problem that the pickup cannot be performed.

  Here, the radiation curable pressure-sensitive adhesive is a pressure-sensitive adhesive composition containing at least a compound (a) having a carbon-carbon unsaturated bond at an intramolecular end and a compound called an initiator that generates radicals by receiving radiation. It refers to things. By irradiating with radiation, the initiator is activated, and by the generated radical, the terminal carbon-carbon unsaturated bond is subsequently activated, whereby the compound (a) is successively bonded, and the compound ( a) mutual forms a bridge.

  Since the plurality of compounds (a) dispersed in the pressure-sensitive adhesive before cross-linking are aggregated and bonded together, the pressure-sensitive adhesive becomes harder after cross-linking than before cross-linking. When the cross-linking reaction occurs in close contact with the bumps or steps, the hardened adhesive is caught on the bumps or steps and inhibits smooth peeling. In particular, in a wafer having a through electrode, since the bump is formed through the inside of the wafer, the chip strength is extremely weak, and chip breakage is liable to occur when peeling is inhibited. The bumps caused by the curing of the pressure-sensitive adhesive or the catching on the step can be suppressed by adjusting the degree of curing of the pressure-sensitive adhesive.

  As an index for checking the degree of curing of the pressure-sensitive adhesive, there is a tensile elastic modulus of the radiation-curing dicing pressure-sensitive adhesive tape 1. The closer 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, the smaller the change in hardness from before crosslinking is formed. Means. As described above, the radiation-curable pressure-sensitive adhesive layer 3 undergoes a curing reaction upon irradiation with radiation, and thus the above ratio is usually larger than 1. When this ratio is 1.8 or less, there is little catching on bumps or steps, and pickup can be performed easily. If it is larger than 1.8, bumps or bumps will be caught, and the stress applied to the chip will increase when the pickup process is pushed up, so that pickup cannot be performed or the chip may be damaged. To do.

  Note that the tensile modulus here is a value obtained in accordance with JIS K 7127: 1999. Moreover, although the base material sheet 2 is generally thicker and more rigid than the pressure-sensitive adhesive layer 3, only the pressure-sensitive adhesive layer 3 is obtained by taking the ratio of the tensile elastic modulus of the radiation-curable dicing pressure-sensitive adhesive tape 1. Comparison of tensile modulus of

But it is not limited here dose of radiation, especially, for example, in the case of UV, preferably 100~1000mJ / cm ^2, more preferably 200~500mJ / cm ^2.

In order to prevent chipping of the semiconductor chip, the storage elastic modulus G ′ of the pressure-sensitive adhesive layer 3 before radiation curing is preferably 2.0 × 10 ^{4 to} 4.5 × 10 ⁴ Pa. When G ′ is lower than 2.0 × 10 ⁴ Pa, the pressure-sensitive adhesive layer 3 can sufficiently adhere to bumps or steps, but because the pressure-sensitive adhesive layer 3 is too soft, it is caused by a rotating blade in the dicing process. Vibration cannot be suppressed and chipping occurs. In addition, when the pressure is larger than 4.5 × 10 ⁴ Pa, the adhesive layer 3 cannot be sufficiently adhered to the bump or the step, and a gap is formed. Therefore, the chipping is caused by the vibration of the rotary blade in the dicing process. Will occur.

  Further, in order to maintain the state where the adhesive layer 3 is sufficiently adhered to the bumps or steps, the loss factor tan δ of the adhesive layer 3 before radiation curing is preferably 0.25 or more. The loss coefficient tan δ is represented by a ratio (G ″ / G ′) between the storage elastic modulus G ′ and the loss elastic modulus G ″. When tan δ is small, even when the pressure-sensitive adhesive layer 3 can sufficiently adhere to bumps or steps, it is difficult to maintain the close contact state because of its high resilience. When the loss coefficient tan δ of the pressure-sensitive adhesive layer 3 is smaller than 0.25, the close contact state cannot be maintained, and a gap is generated between the wafer and the pressure-sensitive adhesive tape, and chipping may be deteriorated by the above-described mechanism.

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

(Base material sheet 2)
About resin which comprises the base material sheet 2, it does not restrict | limit in particular, Resin which can be formed in a sheet form can be used. For example, for example, polypropylene, high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene / propylene copolymer, propylene copolymer, ethylene-propylene-diene copolymer added Sulfur, polybutene, polybutadiene, polymethylpentene, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) methyl acrylate copolymer, ethylene- (meth) ethyl acrylate copolymer, ethylene- (meta ) Butyl acrylate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl chloride-vinyl acetate copolymer, polyurethane, polyamide, ionomer, nitrile rubber, butyl rubber, styrene isoprene rubber, styrene butadiene rubber , Natural rubber and so Water additives or modified, etc., etc. may be used. These resins can be used alone or in admixture of two or more, and can also have a multilayer structure of two or more layers.

  The thickness of the base sheet 2 is not particularly limited. However, if it is too thin, it is difficult to handle, and if it is too thick, it becomes difficult to transmit the stress of the push-up jig during the pickup process. preferable.

  In order to improve the adhesiveness, the surface of the base sheet 2 that contacts the pressure-sensitive adhesive layer 3 may be subjected to corona treatment or treatment with a primer or the like.

(Adhesive layer 3)
As the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer 3, for example, those described in JP-A-7-135189 are preferably used, but the invention is not limited to these, and a rubber-based or acrylic base polymer In contrast, 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 base What added the compound which has a carbon-carbon double bond to a polymer can be used.

  The method for introducing a carbon-carbon double bond into an acrylic polymer is not particularly limited. For example, an acrylic polymer containing a functional group by copolymerization using a monomer having a functional group as a copolymerizable monomer. After preparing the polymer, a compound having a functional group capable of reacting with a functional group in the acrylic polymer containing a functional group and a carbon-carbon double bond is converted into a carbon-carbon to the acrylic polymer containing the functional group. Examples thereof include a method for preparing an acrylic polymer having a carbon-carbon double bond in the molecule by carrying out a condensation reaction or an addition reaction while maintaining the radiation curing property (radiation polymerization property) of the double bond.

  The above rubber-based or acrylic base polymer is a rubber-based polymer such as natural rubber or various synthetic rubbers, or poly (meth) acrylic acid alkyl ester, (meth) acrylic acid alkyl ester, (meth) acrylic acid alkyl ester. And an acrylic polymer such as a copolymer of the above and other unsaturated monomer copolymerizable therewith. Use of ethyl acrylate, butyl acrylate, or methoxyethyl acrylate as the monomer constituting the base polymer is preferable because the pickup property is further improved.

  Examples of the photopolymerizable compound include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol. Esterified product of (meth) acrylic acid such as di (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerin di (meth) acrylate and polyhydric alcohol; ester acrylate oligomer; 2-propenyl-di-3- Cyanurate compounds having a carbon-carbon double bond-containing group such as butenyl cyanurate; tris (2-acryloxyethyl) isocyanurate, tris (2-methacryloxyethyl) isocyanurate, 2-hydroxyethyl Bis (2-acryloxyethyl) isocyanurate, bis (2-acryloxyethyl) 2-[(5-acryloxyhexyl) -oxy] ethyl isocyanurate, tris (1,3-diaacryloxy-2-propyl-oxycarbonyl Amino-n-hexyl) isocyanurate, tris (1-acryloxyethyl-3-methacryloxy-2-propyl-oxycarbonylamino-n-hexyl) isocyanurate, tris (4-acryloxy-n-butyl) isocyanurate, etc. Examples include isocyanurate compounds having a carbon-carbon double bond-containing group. These photopolymerizable compounds can be used alone or in combination of two or more.

  If the tensile Young's modulus ratio before and after radiation curing is 1.8 or less, the number of carbon-carbon double bonds in one molecule is not particularly limited, but the number of carbon-carbon double bonds in one molecule is 2-6. Is preferred. Moreover, although there is no restriction | limiting in particular also about a compounding quantity, 10-90 mass parts is preferable with respect to 100 mass parts of said base polymers of an adhesive, and 20-70 mass parts is more preferable.

  The radiation-curable pressure-sensitive adhesive can generate a polymerization and curing reaction by radiation irradiation by mixing a photopolymerization initiator in the pressure-sensitive adhesive. Examples of such photopolymerization initiators include benzoin alkyl ether initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, benzoylbenzoic acid, 3,3 ′ Benzophenone initiators such as dimethyl-4-methoxybenzophenone and polyvinylbenzophenone; α-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio) Aromatic ketone initiators such as phenyl] -2-morpholinopropane-1; aromatic ketal initiators such as benzyldimethyl ketal; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropyl Thioxanthone initiators such as thioxanthone, 2-dodecylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, benzyl initiators such as benzyl, benzoin In addition to benzoin initiators such as α-ketol compounds (such as 2-methyl-2-hydroxypropiophenone), aromatic sulfonyl chloride compounds (such as 2-naphthalenesulfonyl chloride), and photoactive oxime compounds (1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime, etc.), camphorquinone, halogenated ketone, acyl phosphinoxide, acyl phosphonate and the like. A photoinitiator can be used individually or in combination of 2 or more types.

  Although the compounding quantity of a photoinitiator is not restrict | limited in particular, Preferably it is 1-10 mass parts with respect to 100 mass parts of said base polymers of an adhesive, More preferably, it is 2-7 mass parts.

  In the above-mentioned pressure-sensitive adhesive, an isocyanate curing agent can be blended as necessary. Specific examples of the isocyanate curing agent include polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene 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 is used.

  Although the compounding quantity of a hardening | curing agent is not restrict | limited in particular, Preferably it is 0.01-10 mass parts with respect to 100 mass parts of said base polymers of an adhesive, More preferably, it is 0.1-5 mass parts.

  In the pressure-sensitive adhesive composition for forming the radiation-curable pressure-sensitive adhesive, for example, a tackifier, an anti-aging agent, a filler, a colorant, a flame retardant, an antistatic agent, a softening agent, an ultraviolet ray may be used as necessary. Known additives such as an absorbent, an antioxidant, a plasticizer, and a surfactant may be included.

  The pressure-sensitive adhesive layer 3 in the present invention can be formed using a known method for forming the pressure-sensitive adhesive layer 3. For example, the above-mentioned pressure-sensitive adhesive composition is applied to a predetermined surface of the base sheet 2 and formed, or the pressure-sensitive adhesive composition is separated from a separator (for example, a plastic film or sheet coated with a release agent). The adhesive layer 3 can be formed on the base sheet 2 by a method in which the adhesive layer 3 is formed on the base sheet 2 by transferring the adhesive layer 3 to a predetermined surface of the base sheet 2. it can. The thickness of the pressure-sensitive adhesive layer 3 is not particularly limited as long as it is higher than bumps or steps.

In addition, in FIG. 1, although the adhesive layer 3 showed the radiation-curing-type dicing adhesive tape 1 which has a single layer form, you may have the form on which the several adhesive layer 3 was laminated | stacked. When the several adhesive layer 3 is laminated | stacked, the adhesive layer 3 which has the surface where a wafer is bonded at the time of dicing is the radiation curing type adhesive layer 3, and the storage elastic modulus G 'before radiation curing Is 2.0 × 10 ^{4 to} 4.5 × 10 ⁴ Pa, and the loss coefficient tan δ before radiation curing is preferably 0.25 or more.

Moreover, you may stick the synthetic resin film normally used as a separator in order to protect the adhesive layer 3 to the adhesive layer 3 side until it uses for practical use as needed. Examples of the constituent material of the synthetic resin film include synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, and paper. The surface of the synthetic resin film may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, fluorine treatment, etc., as necessary, in order to enhance the peelability from the pressure-sensitive adhesive layer 3. The thickness of the synthetic resin film is usually about 10 to 100 μm, preferably about 25 to 50 μm.

<How to use>
Next, the usage method of the radiation curing type dicing adhesive tape 1 of the present invention will be described.

  The radiation curable dicing pressure-sensitive adhesive tape 1 of the present invention is subjected to dicing according to a conventional method after a mounting step for attaching to a semiconductor component as a workpiece, and further transferred to radiation irradiation and a pick-up step. Examples of the semiconductor component include a silicon semiconductor, a compound semiconductor, a semiconductor package, glass, ceramics, and the like. The radiation curable dicing adhesive tape 1 can be suitably used for dicing a semiconductor wafer having a through electrode.

  In the mounting process, the object to be cut and the pressure-sensitive adhesive tape 1 are usually overlapped with the object to be cut and the pressure-sensitive adhesive tape 1 while being pressed by a known pressing means such as a pressing means using a pressure-bonding roll. Paste. When the contact with the workpiece is not sufficient, a method of heating the workpiece can also be adopted.

  In the dicing process, the blade is rotated at a high speed to cut the object to be cut into a predetermined size. Dicing can employ a cutting method called full cut that cuts up to a part of the dicing tape.

After dicing, the pressure-sensitive adhesive layer 3 is cured by irradiation with ultraviolet rays to reduce the adhesiveness. By the ultraviolet irradiation, the tackiness of the pressure-sensitive adhesive layer 3 is lowered by curing, and peeling can be facilitated. But it is not limited here irradiation amount of the ultraviolet is particularly preferably 100~1000mJ / cm ^2, more preferably 200~500mJ / cm ^2.

  After the ultraviolet irradiation, it is used for a pickup process. The pickup process can be provided with an expanding process. The pickup method is not particularly limited, and various conventionally known pickup methods can be employed. For example, there is a method of pushing up individual cut pieces from a dicing tape with a jig such as a needle and picking up the cut pieces with a pickup device.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

<Resin composition constituting the pressure-sensitive adhesive layer>
The following A to H were prepared as the resin composition constituting the pressure-sensitive adhesive layer.

(Adhesive composition A)
For 100 parts by mass of an acrylic copolymer (ethyl acrylate: 23 mol%, butyl acrylate: 56 mol%, methoxyethyl acrylate: 21 mol%) and 100 parts by mass of an acrylic copolymer (weight average molecular weight 900,000) Manufactured, trade name Coronate L) 2 parts by mass, tetramethylolmethane tetraacrylate 30 parts by weight as a photopolymerizable compound, and 2 parts by weight of a photopolymerization initiator (Ciba Geigy Japan, trade name Irgacure 184) are added and mixed. A radiation-curable pressure-sensitive adhesive composition A was prepared.

(Adhesive composition B)
A pressure-sensitive adhesive composition B was prepared in the same manner as the pressure-sensitive adhesive composition A, except that the photopolymerizable compound was changed to 60 parts by mass of pentaerythritol triacrylate.

(Adhesive composition C)
The pressure-sensitive adhesive composition C was prepared in the same manner as the pressure-sensitive adhesive composition A except that the acrylic polymer was a copolymer (weight average molecular weight 500,000) composed of 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate. It was adjusted.

(Adhesive composition D)
The pressure-sensitive adhesive composition D was prepared in the same manner as the pressure-sensitive adhesive composition C, except that the photopolymerizable compound was dipentaerythritol hexaacrylate and the blending amount was 20 parts by mass.

(Adhesive composition E)
A pressure-sensitive adhesive composition E was prepared in the same manner as the pressure-sensitive adhesive composition D, except that the amount of the photopolymerizable compound was 50 parts by mass.

(Adhesive composition F)
The pressure-sensitive adhesive composition F was prepared in the same manner as the pressure-sensitive adhesive composition D, except that the amount of the photopolymerizable compound was 80 parts by mass.

(Adhesive composition G)
As a compound having a photopolymerizable carbon-carbon double bond and a functional group on 100 parts by mass of an acrylic copolymer composed of 2-ethylhexyl acrylate, methacrylic acid, and 2-hydroxyethyl acrylate, 2-methacryloyloxyethyl isocyanate (Showa Residue having an acrylic monomer part having a radiation-curable carbon-carbon double bond-containing group with respect to the repeating unit of the main chain, by reacting 0.2 part by mass, manufactured by Denko Co., Ltd., trade name Karenz MOI) Was obtained (weight average molecular weight 600,000). 1 part by mass of a polyisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., trade name Coronate L) and 2 parts by weight of a photopolymerization initiator (manufactured by Ciba Geigy Japan Inc., trade name: Irgacure 184) with respect to 100 parts by mass of the polymer. In addition, mixing was performed to prepare a radiation-curable pressure-sensitive adhesive composition G.

(Adhesive composition H)
The pressure-sensitive adhesive composition H was prepared in the same manner as the pressure-sensitive adhesive composition G, except that the blending amount of the polyisocyanate compound was 0.5 parts by mass.

(Adhesive composition I)
The pressure-sensitive adhesive composition I was prepared in the same manner as the pressure-sensitive adhesive composition G, except that the amount of 2-methacryloyloxyethyl isocyanate to be reacted with the acrylic copolymer was 0.6 parts by mass.

<Base material sheet>
The following J to L were prepared as substrate sheets.

(Base material sheet J)
Film extrusion molding of ethylene-methacrylic acid- (2-methyl-propyl acrylate) -Zn ++ ionomer resin (Mitsui / DuPont Polychemical Co., Ltd., trade name Himiran AM7316) at about 200 ° C. with a twin-screw kneader A base sheet J having a thickness of 100 μm was manufactured.

(Substrate sheet K)
An ethylene-vinyl acetate copolymer (manufactured by Nippon Unicar Co., Ltd., trade name NUC-3758) was subjected to film extrusion at about 200 ° C. with a twin-screw kneader to produce a substrate sheet K having a thickness of 100 μm.

(Base material sheet L)
A polyvinyl chloride sheet (thickness: 100 μm) containing 30 parts by weight of dioctyl phthalate with respect to 100 parts by weight of the polyvinyl chloride resin was prepared.

<Preparation of radiation curable dicing adhesive tape>
As shown in Table 1 and Table 2, the adhesive compositions A to I are applied to each of the base sheet J to L so that the thickness after drying is 20 μm, respectively. The layer was formed and the radiation-curing type dicing pressure-sensitive adhesive tape according to Examples 1 and 3 to 9 and Comparative Examples 1 and 2 was produced. In addition, the pressure-sensitive adhesive composition A was applied so that the thickness after drying was 25 μm to form a pressure-sensitive adhesive layer, and a radiation-curable dicing pressure-sensitive adhesive tape according to Example 2 was produced.

<Young's modulus ratio of adhesive tape>
Using the radiation curable dicing adhesive tapes of Examples 1 to 9 and Comparative Examples 1 and 2, according to JIS K7127 / 2/300, test pieces were prepared and subjected to a tensile test, and the Young's modulus before ultraviolet irradiation was calculated. did. Further, from the substrate sheet side of the pressure-sensitive adhesive tape test sample, ultraviolet rays were irradiated at 200 mJ / mm ² to cure the pressure-sensitive adhesive layer, and then the same test was performed to calculate the Young's modulus after the ultraviolet light irradiation. In each test, the average value of the number n = 5 was used as the test result. From these results, the Young's modulus ratio ((after ultraviolet irradiation) / (before ultraviolet irradiation)) was calculated. The results are shown in Tables 1 and 2.

<Viscoelasticity of adhesive layer>
The pressure-sensitive adhesive compositions A to I were each coated on a release film so that the thickness after drying was 20 μm, and after the pressure-sensitive adhesive layer was formed, the pressure-sensitive adhesive layer was peeled off from the release film. A test sample was prepared by superimposing such that the thickness was about 2 mm. The test sample was punched into a disk shape having a diameter of 8 mm, sandwiched between parallel plates, and measured using a viscoelasticity measuring device (trade name ARES, manufactured by Rheometrics) under the following conditions. The maximum and minimum values of the storage modulus G ′ and the minimum value of the loss coefficient tan δ were recorded from the acquired data. The results are shown in Tables 1 and 2.
(Measurement condition)
Measurement temperature: 23-80 ° C
Temperature increase rate: 5 ° C / min
Measurement frequency: 0.15 Hz

<Evaluation of radiation curable adhesive tape for dicing>
An Si wafer having a thickness of 8 inches and a thickness of 30 μm in which ball bumps 5 (see FIG. 2) having a diameter of 10 μm are formed at intervals of 100 μm was prepared. And the adhesive tape for radiation hardening type dicing of Examples 1-8 and Comparative Examples 1 and 2 was bonded together with the ring frame.

(Embeddability evaluation)
The presence or absence of bubbles around the ball bumps was visually observed from above the adhesive tape surface for radiation curable dicing immediately after bonding. The case where there was no bubble was marked with ◎, the case where the bubble size was 10 μm or less was marked with ○, and the case where the bubble size was larger than 10 μm was marked with ×. The results are shown in Tables 1 and 2.

(Evaluation of changes over time after bonding)
After pasting, it was left in a dicing cassette for 1 hour, and then the same evaluation as the embedding evaluation was performed. The case where there was no change from the evaluation of embeddability was evaluated as ◯, the case where the expansion width of the bubble size was 5 μm or less, and the case where the expansion width of the bubble size was larger than 5 μm. The results are shown in Tables 1 and 2.

Thereafter, using a dicing apparatus (trade name DAD-340, manufactured by DISCO), dicing was performed under the following conditions so that the size of the chip 4 became 10 mm square as shown in FIG. The ball bump 5 is formed as shown in FIG. 2 and is not formed on the scribe line.
(Dicing conditions)
Blade: "27HECC" manufactured by DISCO
Blade rotation speed: 40000 rpm
Dicing speed: 50mm / sec
Dicing depth: 25μm
Cut mode: Down cut

(Pickup evaluation)
After curing the pressure-sensitive adhesive layer by irradiating UV radiation at 200 mJ / mm ² from the base sheet side of the radiation-curing pressure-sensitive adhesive tape for dicing, the separated chip is formed into a die picker device (trade name, manufactured by Canon Machinery Co., Ltd.) Pickup using CAP-300II). Pick up 50 arbitrary chips under the following conditions A and B, count the number of chips successfully picked up, and if all 50 chips have been successfully picked up, ○ The pick-up property was evaluated as △ when the pick-up was successful, and x otherwise. The results are shown in Tables 1 and 2. Note that the pickup failure refers to the case where the peeling cannot be performed and the case where the picked-up chip is cracked.
(Pickup condition A)
Number of pins: 5 Pin spacing: 7.8 x 7.8 mm
Pin tip curvature: 0.25mm
Pin push-up amount: 0.30mm
(Pickup condition B)
Number of pins: 5 Pin spacing: 7.8 x 7.8 mm
Pin tip curvature: 0.25mm
Pin push-up amount: 0.40mm

(Chipability evaluation)
The back surface of 30 chips collected in the pickup property evaluation was observed with an optical microscope, and the size of chipping was measured. The case where the distance from the end of the chip to the deepest part of chipping was 5 μm or less was indicated as “◯”, the case where it was 6 to 15 μm as Δ, and the case where it was larger than 15 μm as “X”. The results are shown in Tables 1 and 2.

  As shown in Tables 1 and 2, the radiation-curable dicing pressure-sensitive adhesive tapes of Examples 1 to 9 have a ratio of Young's modulus after radiation curing to Young's modulus before radiation curing of 1.8 or less. The pickup property was good. In particular, in Examples 1 to 4, since ethyl acrylate, butyl acrylate, and methoxyethyl acrylate are used as the monomers constituting the base polymer, the pickup is performed even under the condition A where the pick-up amount of the pin is small and the pickup is more difficult The property was good. In Examples 5 to 9, since ethyl acrylate, butyl acrylate, and methoxyethyl acrylate were not used as the monomers constituting the base polymer, a chip that failed to be picked up was generated in Condition A, but an allowable range was generated. It was a ratio. On the other hand, since the ratio of the Young's modulus after radiation curing to the Young's modulus before radiation curing exceeds 1.8 in the radiation curing type dicing adhesive tapes of Comparative Examples 1 and 2, both conditions A and B are good. Could not pick up.

In addition, the radiation curable dicing pressure-sensitive adhesive tapes of Examples 1 to 6 have a storage elastic modulus G ′ of 2.0 × 10 ^{4 to} 4.5 × 10 ⁴ Pa before the radiation curing of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive. Since the loss coefficient tan δ before radiation curing of the layer was 0.25 or more, all of embeddability, chipping property, and change with time after bonding were good. In contrast, the radiation curing type dicing pressure-sensitive adhesive tape of Example 7 has a storage elastic modulus G ′ before the radiation curing of the pressure-sensitive adhesive layer exceeding 4.5 × 10 ⁴ Pa. Compared to the adhesive tape for mold dicing, the embedding property was inferior and the chipping property was lowered, but it was within an allowable range. Moreover, since the storage elastic modulus G 'before the radiation curing of the pressure-sensitive adhesive layer is lower than 2.0 × 10 ⁴ , the radiation-curable dicing pressure-sensitive adhesive tape of Example 8 is used for the radiation-curable dicing of Examples 1 to 6. Although the chipping property was inferior to that of the adhesive tape, it was within an allowable range. In addition, the radiation curing type dicing pressure-sensitive adhesive tape of Example 9 has a loss coefficient tan δ before radiation curing of the pressure-sensitive adhesive layer smaller than 0.25, and therefore, compared with the radiation curing type dicing pressure-sensitive adhesive tapes of Examples 1 to 6. The wafer floated due to the change with time after bonding, and the chipping property was lowered, but it was within an allowable range.

1: Radiation-curable adhesive tape for dicing 2: Substrate sheet 3: Adhesive layer 4: Chip 5: Ball bump

Claims (5)

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

Images