JP2013197390A - Dicing sheet and method of manufacturing semiconductor chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dicing sheet which can be diced and picked up without breaking a chip while a residue of a pressure-sensitive adhesive layer is not left between projection electrodes (through electrodes).SOLUTION: A dicing sheet 10 comprises a base material 3, an intermediate layer 2 provided to one side thereof and made of an urethane-containing cured body, and a pressure-sensitive adhesive layer 1 provided on the intermediate layer 2 and having a thickness of 8-30 μm. The intermediate layer 2 has a storage elastic modulus G' of 10or larger and less than 10Pa at 23°C, and the pressure-sensitive adhesive layer 1 contains a compound having energy-beam curable double bonds in a molecule, and has the storage elastic modulus G' of 3×10Pa or larger at 23°C. When the dicing sheet is stuck on a wafer 30 where columnar electrodes 20 of 15 μm in height and 15 μm in diameter are formed in three rows and three columns at equal intervals of 40 μm in pitch with the pressure-sensitive adhesive layer 1 interposed, the pressure-sensitive adhesive layer 1 does not come into contact with a portion of 7.5 μm or less of an electrode in the center of the columnar electrodes 20 formed in the three rows and three columns.

Description

  The present invention relates to a dicing sheet used for fixing a semiconductor wafer when a semiconductor wafer is separated into individual circuits and semiconductor chips are formed. The present invention also relates to a method for manufacturing a semiconductor chip using the dicing sheet. In particular, the dicing sheet of the present invention is preferably used when a semiconductor wafer having protruding electrodes on its surface, for example, a semiconductor wafer having a so-called through electrode (TSV) is fixed and cut to manufacture a chip.

  After a circuit is formed on the surface of the semiconductor wafer, a grinding process is performed on the back side of the wafer, and a back grinding process for adjusting the thickness of the wafer and a dicing process for dividing the wafer into a predetermined chip size are performed. Further, following the back surface grinding step, there may be a case where processing on the back surface is accompanied by heat generation such as an etching process, or processing performed at a high temperature such as vapor deposition of a metal film on the back surface. A semiconductor wafer (semiconductor chip) separated into chips is picked up and transferred to the next process.

  With the spread of IC cards in recent years, the semiconductor chip that is a constituent member thereof is being made thinner. For this reason, it has been required to reduce the thickness of a conventional wafer having a thickness of about 350 μm to 50 to 100 μm or less.

  In response to the increase in capacity and functionality of electronic circuits, the development of stacked circuits in which a plurality of semiconductor chips are stacked three-dimensionally is in progress. Conventionally, in such a laminated circuit, the conductive connection of the semiconductor chip is generally performed by wire bonding. However, due to the recent need for miniaturization and high functionality, the semiconductor chip can be connected without wire bonding. An effective method has been developed in which a chip is provided with an electrode (penetrating electrode) penetrating from the circuit formation surface to the back surface and directly conductively connected between the upper and lower chips.

  As a method of manufacturing such a chip with a through electrode, for example, a through hole is formed in a predetermined position of a semiconductor wafer by plasma or the like, a conductor such as copper is poured into the through hole, and then etching or the like is applied to the semiconductor. Examples thereof include a method of providing a circuit and a through electrode on the surface of the wafer. A semiconductor wafer provided with a circuit and a through electrode is diced using a dicing sheet in which an adhesive layer is formed on a base film, and individual chips with through electrodes are obtained.

  In the chip with a through electrode as described above, the through electrode protrudes on any surface of the chip (protruding electrode). In the dicing process for obtaining a chip with a through electrode, the adhesive layer formed on the base film is deformed by being pressed against the through electrode protruding on the pasting surface, and has substantially the same shape as the protruding portion of the electrode. A method has been proposed in which an electrode is embedded in a recessed portion of an adhesive layer so that a semiconductor wafer on which a through electrode is formed is attached and fixed to a dicing sheet, and then dicing is performed to obtain individual chips (Patent Document 1). , 2). However, in the dicing sheets described in Patent Documents 1 and 2, since the adhesive layer is embedded in the through electrode, the adhesive layer residue may remain between the through electrodes. The residue may contaminate the chip surface and reduce the reliability of the semiconductor chip. In the methods of Patent Documents 1 and 2, such a residual residue reducing means has been proposed, but it cannot be said that the possibility of residual residue can be completely eliminated. Further, in the dicing sheets described in Patent Documents 1 and 2, the elasticity during dicing needs to be adjusted to be low in order to embed the through electrode. For this reason, the chip | tip chip | tip (chipping) was easy to generate | occur | produce by the vibration at the time of dicing.

JP 2006-202926 A JP 2010-135494 A

  The present invention seeks to solve the problems associated with the prior art as described above. That is, an object of the present invention is to provide a dicing sheet that can be diced and picked up without causing a residue of the adhesive layer to remain between the protruding electrodes (through electrodes) and without damaging the chip.

The gist of the present invention aimed at solving such problems is as follows.
[1] A substrate, an intermediate layer made of a urethane-containing cured product provided on one side thereof, and a pressure-sensitive adhesive layer having a thickness of 8 to 30 μm provided on the intermediate layer,
The storage elastic modulus G ′ at 23 ° C. of the intermediate layer is 10 ⁴ Pa or more and less than 10 ⁵ Pa,
The pressure-sensitive adhesive layer contains a compound having an energy ray-curable double bond in the molecule,
The storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is 3 × 10 ⁵ Pa or more,
When a cylindrical electrode having a height of 15 μm and a diameter of 15 μm is pasted through a pressure-sensitive adhesive layer on a wafer in which a cylindrical electrode having a pitch of 40 μm is formed at equal intervals in 3 rows and 3 columns, a cylindrical shape formed in 3 rows and 3 columns A dicing sheet characterized in that, in the electrode at the center of the electrode, the pressure-sensitive adhesive layer does not contact a portion of the electrode having a height of 7.5 μm or less.

[2] The dicing sheet according to [1], wherein the intermediate layer is a cured product of a blend containing a urethane oligomer having a weight average molecular weight of 10,000 or more, an energy ray-curable monomer having a molecular weight of less than 1000, and a photopolymerization initiator. .

[3] The compound having an energy beam curable double bond in the molecule includes an energy beam curable adhesive polymer in which an energy beam polymerizable group is bonded to the main chain or side chain of the polymer [1. ] Or the dicing sheet according to [2].

[4] The pressure-sensitive adhesive layer contains an acrylic polymer having a reactive functional group and a crosslinking agent,
The dicing sheet according to any one of [1] to [3], which contains 5 parts by mass or more of a crosslinking agent with respect to 100 parts by mass of the acrylic polymer.

[5] The dicing sheet according to [4], wherein the crosslinking agent is an isocyanate-based crosslinking agent.

[6] The dicing sheet according to any one of [1] to [5], wherein the dicing sheet is used by being attached to a wafer provided with a protruding electrode.

[7] The dicing sheet according to [6], wherein the protruding electrode is a through electrode.

[8] The dicing sheet according to [6] or [7], wherein the intermediate layer has a thickness of 0.5 to 1.5 times the height of the protruding electrode.

[9] A step of affixing the dicing sheet according to any one of [1] to [8] to a surface of the semiconductor wafer having the projecting electrodes, wherein the semiconductor wafer is divided into individual circuits. A method for manufacturing a semiconductor chip, comprising a step of manufacturing a semiconductor chip and a step of picking up the semiconductor chip.

  When the dicing sheet according to the present invention is adhered to a semiconductor wafer, the pressure-sensitive adhesive layer does not follow between the protruding electrodes, but follows the outer peripheral portion of the region where the protruding electrodes are formed (electrode forming region). . As a result, no residue of the pressure-sensitive adhesive layer remains between the projecting electrodes, and residual residue at the outer periphery of the electrode formation region due to polymerization failure is also suppressed. In addition, the adhesive layer is attached to the semiconductor wafer at the outer periphery of the electrode formation area, and the adhesive layer is not excessively flexible, preventing water from entering during dicing, excellent dicing properties, and chipping. Can be prevented. Moreover, since the adhesive force can be controlled by curing the pressure-sensitive adhesive layer with energy rays, chip pick-up is easy and breakage of the chip can be prevented.

It is a schematic sectional drawing of the dicing sheet concerning this invention. It is a schematic sectional drawing which shows the state which affixed the dicing sheet which concerns on this invention to the wafer in which the cylindrical electrode was formed. The top view of the circuit formation surface of the semiconductor wafer in which the cylindrical electrode was formed is shown.

  Hereinafter, the dicing sheet according to the present invention will be specifically described. As shown in FIG. 1, a dicing sheet 10 according to the present invention includes a base material 3, an intermediate layer 2 provided on one side thereof, and an adhesive layer 1 provided on the intermediate layer 2.

(Adhesive layer 1)
The storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is 3 × 10 ⁵ Pa or more, preferably 3.5 × 10 ⁵ to 1 × 10 ⁷ Pa. When the storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is less than 3 × 10 ⁵ Pa, the pressure-sensitive adhesive layer follows between the protruding electrodes to be described later, and generation of residues of the pressure-sensitive adhesive layer between the protruding electrodes Chip breakage during pick-up occurs. By setting the storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer in the above range, the effect of suppressing the follow-up between the protruding electrodes of the pressure-sensitive adhesive layer and the like can be obtained more reliably. Further, the storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is preferably larger than 4 times the storage elastic modulus G ′ at 23 ° C. of the intermediate layer, more preferably the storage elastic modulus G ′ of the intermediate layer at 23 ° C. It is larger than 5 times. In this way, the adhesive layer having relatively high elasticity exists so as to cover the intermediate layer 2 having a low elastic modulus, so that the adhesive layer can be suitably prevented from following between the protruding electrodes. It is possible to prevent the occurrence of a residue of the adhesive layer in the meantime and damage of the chip during pickup. The storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is a storage elastic modulus before the pressure-sensitive adhesive layer is cured by energy ray irradiation.

  The thickness of an adhesive layer is 8-30 micrometers, More preferably, it is the range of 8-25 micrometers. When the thickness of the pressure-sensitive adhesive layer is in the above range, the dicing property is improved and the occurrence of chipping can be suppressed. In addition, it is preferable to prevent the pressure-sensitive adhesive layer from following between the protruding electrodes, and it is possible to prevent generation of residue of the pressure-sensitive adhesive layer between the protruding electrodes and damage of the chip during pick-up, and formation of the protruding electrodes The followability of the dicing sheet at the outer periphery of the formed region (electrode formation region) is maintained.

  The pressure-sensitive adhesive layer includes a compound composed of a compound having an energy ray-curable double bond in the molecule and a substance for expressing adhesiveness (hereinafter sometimes referred to as “energy ray-curable pressure-sensitive adhesive component”). contains.

  An adhesive layer is formed using the adhesive composition which mix | blended the energy-beam curable adhesive component and the photoinitiator as needed. Furthermore, in order to improve various physical properties, the said adhesive composition may contain the other component as needed. As other components, a crosslinking agent is preferable.

  Hereinafter, the energy ray-curable pressure-sensitive adhesive component will be specifically described using an acrylic pressure-sensitive adhesive as an example.

  The acrylic pressure-sensitive adhesive contains an acrylic polymer (A) for imparting sufficient pressure-sensitive adhesiveness and film-forming property (sheet-forming property) to the pressure-sensitive adhesive composition, and also contains an energy ray-curable compound (B). To do. The energy ray-curable compound (B) contains an energy ray-polymerizable group and has a function of being polymerized and cured when irradiated with energy rays such as ultraviolet rays and electron beams and reducing the adhesive strength of the pressure-sensitive adhesive composition. In addition, as a compound having an energy ray curable double bond in the molecule, an energy ray curable adhesive polymer in which an energy ray polymerizable group is bonded to the main chain or side chain of the polymer (hereinafter referred to as component ( (AB) may be used). Such an energy ray curable pressure-sensitive adhesive polymer (AB) has a property having both adhesiveness and energy ray curable properties.

  A conventionally well-known acrylic polymer can be used as an acrylic polymer (A). The weight average molecular weight (Mw) of the acrylic polymer (A) is preferably 10,000 to 2,000,000, and more preferably 100,000 to 1,500,000. The glass transition temperature (Tg) of the acrylic polymer (A) is preferably in the range of −70 to 30 ° C., more preferably in the range of −60 to 20 ° C.

As a monomer which comprises an acrylic polymer (A), a (meth) acrylic acid ester monomer or its derivative (s) is mentioned.
Specifically, alkyl having 1 to 18 carbon atoms in an alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. (Meth) acrylate;
Cycloalkyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, imide (meth) (Meth) acrylates having a cyclic skeleton such as acrylate;
Hydroxyl group-containing (meth) acrylates such as hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate;
Examples include acrylic acid, methacrylic acid, itaconic acid, glycidyl acrylate, and glycidyl methacrylate.
Vinyl acetate, acrylonitrile, styrene, or the like may be copolymerized.
These may be used alone or in combination of two or more.

  Moreover, it is preferable that the acrylic polymer (A) in this invention has a reactive functional group. The reactive functional group reacts with the reactive functional group of the crosslinking agent preferably added to the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer in the present invention to form a three-dimensional network structure, and the pressure-sensitive adhesive layer at 23 ° C. It becomes easy to adjust the storage elastic modulus G ′ to a predetermined range. Examples of the reactive functional group of the acrylic polymer (A) include a carboxyl group, an amino group, an epoxy group, and a hydroxyl group, and a hydroxyl group is preferable because it can be easily reacted selectively with a crosslinking agent. The reactive functional group is composed of an acrylic polymer (A) by using the monomer having a reactive functional group such as a hydroxyl group-containing (meth) acrylate or acrylic acid as described above. Can be introduced.

  The acrylic polymer (A) preferably contains 5 to 30% by mass, more preferably 10 to 25% by mass of a monomer having a reactive functional group in all the monomers constituting the acrylic polymer (A). By setting the blending ratio of the monomer having a reactive functional group in such a range, the acrylic polymer (A) is efficiently crosslinked by the crosslinking agent, and the storage elastic modulus G ′ of the pressure-sensitive adhesive layer at 23 ° C. Can be easily adjusted to a predetermined range. Moreover, it is preferable that the reactive functional group (for example, hydroxyl group) equivalent of an acrylic polymer (A) is 0.17 to 2.0 times the reactive functional group (for example, isocyanate group) equivalent of a crosslinking agent. By adjusting the relationship between the reactive functional group equivalent of the acrylic polymer (A) and the reactive functional group equivalent of the crosslinking agent within the above range, the storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is adjusted to a predetermined range. It will be easier to do.

  The energy ray curable compound (B) is a compound that is polymerized and cured when irradiated with energy rays such as ultraviolet rays and electron beams. Examples of the energy ray curable compounds include low molecular weight compounds (monofunctional and polyfunctional monomers and oligomers) having an energy ray polymerizable group, and specifically include trimethylolpropane triacrylate and tetramethylolmethane. Acrylates such as tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, dicyclopentadiene dimethoxydiacrylate, Cyclic aliphatic skeleton-containing acrylates such as isobornyl acrylate, polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate Goma, epoxy-modified acrylates, polyether acrylates, acrylate compounds such as itaconic acid oligomer is used. Such a compound has an energy ray-curable double bond in the molecule, and usually has a molecular weight of about 100 to 30,000, preferably about 300 to 10,000.

  Generally, the low molecular weight compound having an energy ray polymerizable group is preferably 0 to 200 parts by mass with respect to 100 parts by mass of the component (A) (including the energy ray curable adhesive polymer (AB) described later). More preferably, it is used in a ratio of about 1 to 100 parts by mass, and more preferably about 1 to 30 parts by mass. The low molecular weight compound having an energy ray polymerizable group softens the pressure-sensitive adhesive layer before curing with energy rays due to its low molecular weight. Then, there is a possibility that the effect of the present invention that the pressure-sensitive adhesive layer hardly follows between the protruding electrodes as described later cannot be sufficiently obtained. For this reason, it is preferable to restrict | limit the usage-amount of the low molecular weight compound which has an energy-beam polymeric group few.

The energy ray curable adhesive polymer (AB) is formed by bonding an energy ray polymerizable group to the main chain or side chain of a polymer. As described above, it is preferable to limit the amount of the low molecular weight compound having an energy ray polymerizable group to be small. However, in this case, the pressure-sensitive adhesive layer is not sufficiently cured by irradiation with energy rays, and the pressure-sensitive adhesive layer is covered. There is a possibility that the effect of suppressing residue on the body will be reduced. Therefore, by applying the energy ray curable pressure-sensitive adhesive polymer (AB) to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer can be cured by irradiation with energy rays without softening the pressure-sensitive adhesive layer before irradiation with energy rays. It can be fully advanced.
In addition, since the energy ray curable adhesive polymer (AB) has an energy ray polymerizable group in the molecule and can also have a reactive functional group, one molecule is bonded to another molecule. Probability is high. For this reason, after irradiating an energy ray and hardening an adhesive layer, possibility that a low molecular component will remain without being taken in into a three-dimensional network structure is low. Therefore, the generation | occurrence | production of the residue resulting from the low molecular component which was not taken in into a three-dimensional network structure and was suppressed is suppressed.

  The main skeleton of the energy ray curable adhesive polymer is not particularly limited, and may be an acrylic copolymer that is widely used as an adhesive. In addition, when energy-beam curable adhesive polymer (AB) is an acrylic polymer, it corresponds also to an acrylic polymer (A).

  The energy beam polymerizable group bonded to the main chain or side chain of the energy beam curable adhesive polymer is, for example, a group containing an energy beam curable carbon-carbon double bond, and specifically, (meth) acryloyl. Examples include groups. The energy beam polymerizable group may be bonded to the energy beam curable pressure-sensitive adhesive polymer via an alkylene group, an alkyleneoxy group, or a polyalkyleneoxy group.

  The weight average molecular weight (Mw) of the energy ray curable adhesive polymer (AB) to which the energy ray polymerizable group is bonded is preferably 10,000 to 2,000,000, more preferably 100,000 to 1,500,000. preferable. The glass transition temperature (Tg) of the energy ray curable adhesive polymer (AB) is preferably in the range of −70 to 30 ° C., more preferably in the range of −60 to 20 ° C.

  The energy ray curable adhesive polymer (AB) reacts with the acrylic adhesive polymer containing a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group, for example, with the functional group. It is obtained by reacting a substituent with a polymerizable group-containing compound having 1 to 5 energy beam polymerizable carbon-carbon double bonds per molecule. Acrylic adhesive polymer is a monomer that comprises (meth) acrylic acid ester monomer or derivative thereof having a functional group such as hydroxyl group, carboxyl group, amino group, substituted amino group, and epoxy group, and component (A) described above. A copolymer consisting of Examples of the polymerizable group-containing compound include (meth) acryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, (meth) acryloyl isocyanate, allyl isocyanate, glycidyl (meth) acrylate; (meth) acrylic acid Etc.

  The acrylic pressure sensitive adhesive containing the acrylic polymer (A) and the energy ray curable compound (B) or the energy ray curable adhesive polymer (AB) as described above is cured by irradiation with energy rays. Specifically, ultraviolet rays, electron beams, etc. are used as the energy rays.

  Examples of photopolymerization initiators include photoinitiators such as benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, and photosensitizers such as amines and quinones. 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone Examples include 2,4,6-trimethylbenzoyldiphenylphosphine oxide. When ultraviolet rays are used as energy rays, the irradiation time and irradiation amount can be reduced by adding a photopolymerization initiator.

  The content of the photopolymerization initiator is theoretically the amount of unsaturated bonds (energy ray curable double bonds) present in the pressure-sensitive adhesive layer, the reactivity thereof, and the reactivity of the photopolymerization initiator used. However, it is not always easy in a complex mixture system. As a general guideline, the content of the photopolymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the energy ray curable compound (B). . If the content of the photopolymerization initiator is less than the above range, a satisfactory pick-up property may not be obtained due to insufficient photopolymerization, and if it exceeds the above range, a residue that does not contribute to photopolymerization is generated, Curability may be insufficient.

  Examples of the crosslinking agent include organic polyvalent isocyanate compounds, organic polyvalent epoxy compounds, organic polyvalent imine compounds, and the like, and organic polyvalent isocyanate compounds (isocyanate-based crosslinking agents) are preferable.

  Examples of organic polyvalent isocyanate compounds include aromatic polyvalent isocyanate compounds, aliphatic polyvalent isocyanate compounds, alicyclic polyvalent isocyanate compounds, trimers of these organic polyvalent isocyanate compounds, and these organic polyvalent isocyanate compounds. Examples thereof include terminal isocyanate urethane prepolymers obtained by reacting with a polyol compound.

  As more specific examples of the organic polyvalent isocyanate compound, 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, trimethylolpropane adduct Examples include tolylene diisocyanate and lysine isocyanate.

  Specific examples of the organic polyvalent epoxy compound include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, Examples include ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine.

  Specific examples of organic polyvalent imine compounds include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinyl propionate, tetra And methylolmethane-tri-β-aziridinylpropionate and N, N′-toluene-2,4-bis (1-aziridinecarboxamide) triethylenemelamine.

  The crosslinking agent is preferably 5 parts by mass or more, more preferably 8 to 35 parts by mass, particularly preferably 100 parts by mass of the acrylic polymer (A) (including the energy ray curable adhesive polymer (AB)). It is used at a ratio of 12 to 30 parts by mass. By making the compounding quantity of a crosslinking agent into the said range, it becomes easy to adjust the storage elastic modulus G 'in 23 degreeC of an adhesive layer in a preferable range.

  In addition to the crosslinking agent, dyes, pigments, deterioration inhibitors, antistatic agents, flame retardants, silicone compounds, chain transfer agents and the like may be added as other components.

  Moreover, the adhesive force before energy beam irradiation of an adhesive layer becomes like this. Preferably it is 500 mN / 25mm or more, More preferably, it is 800-30000 mN / 25mm. Moreover, the adhesive force after energy beam irradiation becomes like this. Preferably it is 10-500 mN / 25mm, More preferably, it is 10-300 mN / 25mm. By setting the adhesive strength of the pressure-sensitive adhesive layer within the above range, the dicing property and the pickup property are excellent.

  In addition, a release sheet may be laminated on the pressure-sensitive adhesive layer in order to protect the pressure-sensitive adhesive layer before use. The release sheet is not particularly limited. For example, a film made of a resin such as polyethylene terephthalate, polypropylene, or polyethylene or a foamed film thereof, paper such as glassine paper, coated paper, laminated paper, silicone-based, fluorine A system and a release agent such as a long chain alkyl group-containing carbamate can be used.

(Intermediate layer 2)
The mid layer 2 is made of a urethane-containing cured product. The urethane-containing cured product is a cured product obtained by energy beam curing of a blend containing a urethane oligomer and / or a urethane (meth) acrylate oligomer and an energy beam curable monomer added as necessary.

  The urethane oligomer is obtained by polyaddition of a polyol compound and a polyvalent isocyanate compound.

  A polyol compound will not be specifically limited if it is a compound which has two or more of hydroxyl groups, A well-known thing can be used. Specifically, for example, any of an alkylene diol, a polyether type polyol, a polyester type polyol, and a polycarbonate type polyol may be used, but a better effect can be obtained by using a polyether type polyol. The polyol is not particularly limited, and may be a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher polyol. From the viewpoint of availability, versatility, and reactivity, It is particularly preferred to use a diol. Accordingly, polyether type diols are preferably used.

  A polyether-type diol, which is a representative example of a polyether-type polyol, is generally represented by HO — (— R—O—) n—H. Here, R is a divalent hydrocarbon group, preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms, and particularly preferably an alkylene group having 3 or 4 carbon atoms. Among the alkylene groups having 1 to 6 carbon atoms, ethylene, propylene or tetramethylene is preferable, and propylene or tetramethylene is particularly preferable. Accordingly, particularly preferred polyether type diols are polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, and more preferred polyether type diols include polypropylene glycol and polytetramethylene glycol. n is the number of repetitions of (—R—O—), preferably about 10 to 250, more preferably about 25 to 205, and particularly preferably about 40 to 185. When n is smaller than 10, the concentration of urethane bonds in the urethane oligomer is increased, and the storage elastic modulus of the intermediate layer is increased. When n is larger than 250, the storage elastic modulus of the intermediate layer is excessively lowered, the intermediate layer is pushed out from the end face of the dicing sheet, and the stacked sheets may adhere to each other at the end or the thickness may not be uniform. There is.

  As the polybasic acid component used for the production of the polyester type polyol, various known ones generally known as polyester polybasic acid components can be used. Specifically, for example, dibasic acids such as adipic acid, maleic acid, succinic acid, oxalic acid, fumaric acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, phthalic anhydride, isophthalic acid Dibasic acids such as acid, terephthalic acid and 2,6-naphthalenedicarboxylic acid, aromatic polybasic acids such as trimellitic acid and pyromellitic acid, their corresponding anhydrides and derivatives, dimer acids, and hydrogenated dimers An acid etc. are mentioned. Polyester polyols can be obtained by polycondensation (esterification reaction) of these polybasic acid components and known glycols. In addition, you may use various well-known catalysts for the said esterification reaction as needed. Examples of the catalyst include tin compounds such as dibutyltin oxide and stannous octylate, and alkoxytitanium such as tetrabutyl titanate and tetrapropyl titanate. Examples of glycols include 1,4-butanediol and 1,6-hexanediol.

  It does not specifically limit as a polycarbonate type polyol, A well-known thing can be used. Specifically, for example, a reaction product of glycols and alkylene carbonates exemplified as those used for the synthesis of polyester-based polyols can be used.

  The molecular weight of the polyol compound calculated from the hydroxyl value is preferably about 1000 to 10,000, and more preferably about 1500 to 9000. If the molecular weight is lower than 1000, the urethane bond concentration of the urethane oligomer may be high, and the storage elastic modulus of the intermediate layer may be high. If the molecular weight is too high, the storage elastic modulus of the intermediate layer may be difficult to decrease.

  The molecular weight of the polyether-type polyol is polyether-type polyol functional group number × 56.11 × 1000 / hydroxyl value [mgKOH / g], which is a value calculated from the hydroxyl value of the polyether-type polyol.

  Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, and dicyclohexylmethane-2,4. Aliphatic diisocyanates such as' -diisocyanate, ω, ω'-diisocyanate dimethylcyclohexane, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene-1, And aromatic diisocyanates such as 5-diisocyanate. Among these, it is preferable to use isophorone diisocyanate, hexamethylene diisocyanate, or xylylene diisocyanate because the viscosity of the urethane oligomer can be kept low and the handleability becomes good.

  As a condition for reacting the polyol compound and the polyvalent isocyanate compound, the polyol compound and the polyvalent isocyanate compound are reacted at about 60 to 100 ° C. for about 1 to 4 hours in the presence of a solvent and a catalyst as necessary. You can do it.

  The urethane (meth) acrylate oligomer is a compound having a (meth) acryloyl group and having a urethane bond. Such a urethane (meth) acrylate oligomer has a hydroxyl group in a terminal isocyanate urethane prepolymer (urethane oligomer) obtained by reacting a polyol compound such as polyester type or polyether type with a polyvalent isocyanate compound. Obtained by reacting (meth) acrylate. In addition, in this specification, (meth) acryl is used in the meaning including both acryl and methacryl. The polyol compound and polyvalent isocyanate compound can similarly illustrate the polyol compound and polyvalent isocyanate compound used in the production of the urethane oligomer.

  The (meth) acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth) acryloyl group in one molecule, and known ones can be used. Specifically, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meta ) Acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate-containing (meth) acrylate N-methylol (meth) acrylamide-containing (meth) acrylamide, vinyl alcohol, vinylphenol, diglycidyl ester of bisphenol A (meth) acrylate And a reaction product obtained by reacting the acrylic acid and the like.

  As conditions for reacting the terminal isocyanate urethane prepolymer and the hydroxy group-containing (meth) acrylate, the terminal isocyanate urethane prepolymer and the hydroxy group-containing (meth) acrylate may be reacted in the presence of a solvent and a catalyst, if necessary. The reaction may be performed at about 60 to 100 ° C. for about 1 to 4 hours.

  The urethane (meth) acrylate oligomer thus obtained has a photopolymerizable double bond in the molecule and has a property of being polymerized and cured by irradiation with energy rays to form a film.

  Said urethane oligomer and urethane (meth) acrylate oligomer can be used individually by 1 type or in combination of 2 or more types.

  The weight average molecular weight of the urethane oligomer (referred to as polystyrene converted by gel permeation chromatography, the same shall apply hereinafter) is not particularly limited, but is preferably 10,000 or more, more preferably 10,000 to 100,000, and still more preferably 10,000 to 75,000. is there. By making a weight average molecular weight into the said range, it can prevent that a urethane oligomer transfers to the adhesive layer mentioned above, and can suppress the fall of the storage elastic modulus G 'of an adhesive layer. As a result, the followability of the dicing sheet in the inner peripheral portion of the electrode formation region is lowered, and the generation of the adhesive layer residue between the electrodes can be prevented. Moreover, when the liquid formulation for forming the intermediate | middle layer 2 by casting film forming is prepared, it is suppressed that the viscosity of a liquid formulation falls too much and coating becomes difficult.

  Although the weight average molecular weight of a urethane (meth) acrylate oligomer is not specifically limited, Preferably it is 5000-70000, More preferably, it is 10000-50000. By setting the weight average molecular weight within the above range, the crosslinking density in the crosslinked structure of the urethane (meth) acrylate oligomer after polymerization and curing is appropriately adjusted, and the storage elastic modulus of the intermediate layer can be easily adjusted to the range described later. . Moreover, when the liquid compound for forming the intermediate | middle layer 2 by casting film forming is prepared, the viscosity of a liquid compound does not increase excessively, but it becomes easy to apply and is preferable. In addition, since the compound containing a urethane (meth) acrylate oligomer has high curability, in order to adjust the storage elastic modulus of the intermediate layer 2 to a preferable range described later, the weight average molecular weight of the urethane (meth) acrylate oligomer is: A range slightly lower than the weight average molecular weight of the urethane oligomer is preferable.

  In addition, since the film formation is often difficult with a composition containing only a urethane oligomer or a urethane (meth) acrylate oligomer, it is usually formed using a composition obtained by adding an energy ray-curable monomer thereto. Thereafter, this is cured to obtain an intermediate layer. In particular, since the urethane oligomer alone does not have energy beam curability, when the urethane (meth) acrylate oligomer is not used in combination, an energy beam curable monomer is used in combination. The energy ray curable monomer has an energy ray polymerizable double bond in the molecule, and particularly in the present invention, an acrylate ester compound having a relatively bulky group is preferably used.

  Specific examples of energy ray curable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. , T-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meta ) Acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, eicosyl (Meth) acrylates having an alkyl group such as (meth) acrylate having 1 to 30 carbon atoms; isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) (Meth) acrylate having an alicyclic structure such as acrylate, cyclohexyl (meth) acrylate, adamantane (meth) acrylate, etc .; having an aromatic structure such as phenylhydroxypropyl acrylate, benzyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate (Meth) acrylate, (meth) acrylate having a heterocyclic structure such as tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, styrene, hydroxyethyl vinyl acetate Le, hydroxybutyl vinyl ether, N- vinyl formamide, vinyl compounds such as N- vinyl pyrrolidone or N- vinyl caprolactam. Moreover, you may use polyfunctional (meth) acrylate as needed.

  The molecular weight of the energy ray curable monomer is preferably less than 1000, more preferably 200 to 900. By setting the molecular weight of the energy ray-curable monomer in the above range, an increase in the viscosity of the compound for forming the intermediate layer can be suppressed, and the coating suitability can be improved.

  Among these, from the viewpoint of compatibility with urethane oligomers and urethane (meth) acrylate oligomers, (meth) acrylates having alicyclic structures having relatively bulky groups, (meth) acrylates having aromatic structures, and complex A (meth) acrylate having a cyclic structure is preferred.

  10-500 mass parts is preferable with respect to 100 mass parts (solid content) of a urethane oligomer or a urethane (meth) acrylate oligomer, and, as for the usage-amount of this energy-beam curable monomer, 30-300 mass parts is more preferable.

  The total amount of the (meth) acrylate having an alicyclic structure, the (meth) acrylate having an aromatic structure, and the (meth) acrylate having a heterocyclic structure as the energy ray curable monomer is a urethane oligomer or a urethane ( 10-200 mass parts is preferable with respect to 100 mass parts (solid content) of a meth) acrylate oligomer, and 30-150 mass parts is preferable. By setting it as such a range, it becomes easy to adjust the storage elastic modulus of an intermediate | middle layer to the range mentioned later.

As the film forming method, a technique called casting film formation (cast film formation) can be preferably employed. Specifically, a liquid compound (a liquid product obtained by diluting a mixture of the above components with a solvent if necessary) is cast into a thin film, for example, on a substrate in the present invention, and then the coating film is irradiated with energy rays. Then, it is polymerized and cured to form an intermediate layer. According to such a manufacturing method, the stress applied to the resin during film formation is small, and the formation of fish eyes is small. Moreover, the uniformity of the film thickness is also high, and the thickness accuracy is usually within 2%. Specifically, ultraviolet rays, electron beams, etc. are used as the energy rays. Further, the irradiation amount is different depending on the type of the energy ray, for example, when ultraviolet rays are used, the ultraviolet intensity is 50~300mW / cm ^2, the amount of ultraviolet irradiation is preferably about 100~1200mJ / cm ^2.

  In order to improve curability, it is preferable to mix | blend a photoinitiator with this compound. As such a photoinitiator, the same thing as what was mentioned above as what can be mix | blended with an adhesive layer is mentioned.

  The amount of the photopolymerization initiator used is preferably 0.05 to 15 parts by mass, more preferably 100 parts by mass with respect to a total of 100 parts by mass of the urethane oligomer and / or urethane (meth) acrylate oligomer and the energy ray curable monomer. It is 0.1-10 mass parts, Most preferably, it is 0.3-5 mass parts.

  The intermediate layer may contain additives such as colorants such as pigments and dyes.

The storage elastic modulus G ′ at 23 ° C. of the intermediate layer 2 is 10 ⁴ Pa or more and less than 10 ⁵ Pa, preferably 10 ^{4 to} 9 × 10 ⁴ Pa, more preferably 10 ⁴ to 8 × 10 ⁴ Pa. When the storage elastic modulus G ′ at 23 ° C. of the intermediate layer 2 is less than 10 ⁴ Pa, the adhesive layer may follow between the protruding electrodes, and a residue of the adhesive layer may be generated between the protruding electrodes. Further, when the storage elastic modulus G ′ at 23 ° C. of the intermediate layer 2 is 10 ⁵ Pa or more, the followability of the dicing sheet in the outer peripheral portion of the electrode forming region is reduced, and the wafer of the present invention is formed on the wafer on which the protruding electrodes are formed. When attaching a dicing sheet, the amount of air that is caught between the wafer and the dicing sheet increases at the outer periphery of the electrode formation region, so that the activity of energy ray curable compounds and the like is partially due to oxygen in the air. It may be lost and the adhesive layer may fail to polymerize when irradiated with energy rays. As a result, adhesive residue may occur at the outer periphery of the electrode formation region. By adjusting the storage elastic modulus G ′ at 23 ° C. of the intermediate layer to the above range, the effect of improving the followability of the dicing sheet in the outer peripheral portion of the electrode forming region can be obtained more reliably. The dicing sheet of the present invention is provided with only an adhesive layer that is usually relatively elastic by providing an intermediate layer having a low modulus of elasticity with respect to the adhesive layer between the adhesive layer and the substrate. Compared to the case, the followability of the dicing sheet in the outer peripheral portion of the electrode formation region is improved. On the other hand, there is no tendency for the pressure-sensitive adhesive layer to follow easily between the protruding electrodes, but this is a state in which the pressure-sensitive adhesive layer having a relatively high elasticity is extended between the protruding electrodes with the protruding electrode as a column. It is considered that the force that the pressure-sensitive adhesive layer tries to maintain the shape and the force that the intermediate layer tries to penetrate between the electrodes antagonize. In the intermediate layer, the (meth) acryloyl group of the urethane (meth) acrylate oligomer, the energy ray polymerizable double bond of the energy ray curable monomer, etc. remain unreacted, and before and after the irradiation of the energy beam to the dicing sheet When the storage elastic modulus G ′ of the intermediate layer at 23 ° C. changes, the storage elastic modulus G ′ of the intermediate layer at 23 ° C. is the storage elastic modulus before the intermediate layer is cured by irradiation with energy rays.

  Further, the thickness of the intermediate layer is preferably 0.5 to 1.5 times, more preferably 1.0 to 1.5 times the height of the protruding electrode described later. The specific thickness of the intermediate layer may be selected from the above preferable range and calculated from the height of the protruding electrode of the applied wafer. When the thickness of the intermediate layer is within the above range, the dicing sheet non-following property between the protruding electrodes and the dicing sheet following property in the outer periphery of the electrode forming region are excellent, the dicing property is improved, and the occurrence of chipping is suppressed. it can.

(Substrate 3)
Although it does not specifically limit as the base material 3, For example, polyethylene films, such as a low density polyethylene (LDPE) film, a linear low density polyethylene (LLDPE) film, a high density polyethylene (HDPE) film, a polypropylene film, a polybutene film, Polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, polyimide film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene (Meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film Fluororesin film, and the film is used consisting of the hydrogenated product or modified product or the like. These crosslinked films and copolymer films are also used. The above-mentioned base material may be one kind alone, or may be a composite film in which two or more kinds are combined.

  Moreover, when using an ultraviolet-ray as an energy ray irradiated in order to harden an adhesive layer and / or an intermediate | middle layer, the base material which has a transmittance | permeability with respect to an ultraviolet-ray is preferable. In addition, when using an electron beam as an energy ray, the base material does not need to be light-transmitting. It is preferable that the base material is colored because an operator can visually recognize that the dicing sheet is attached to the adherend. When visibility of the adherend surface is required, the substrate is preferably transparent.

  Moreover, in order to improve adhesiveness with an intermediate | middle layer, you may perform a corona treatment or a primer layer in the upper surface of a base material, ie, the base-material surface in the side in which an intermediate | middle layer is provided. Various coating films may be applied to the surface opposite to the intermediate layer. The dicing sheet according to the present invention is produced by forming an intermediate layer on one side of the base material as described above and providing an adhesive layer on the intermediate layer. The thickness of the substrate is preferably in the range of 20 to 200 μm, more preferably 25 to 110 μm, particularly preferably 50 to 90 μm. When the thickness of the substrate is large, the force against the bending of the substrate is increased, and the peeling angle at the time of pick-up is difficult to increase. For this reason, the force required for pick-up increases and the pick-up property may be inferior. When the thickness of the substrate is small, there is a concern that film formation may be difficult depending on the material, or that the blade may break when the blade is cut during dicing.

  The method of providing the intermediate layer on the surface of the base material is formed by applying the intermediate layer composition constituting the intermediate layer on the release sheet so as to have a predetermined film thickness, and forming the intermediate layer. The intermediate layer may be formed by directly applying the intermediate layer composition onto the surface of the substrate. The method of providing the pressure-sensitive adhesive layer on the intermediate layer is the same as the method of using the pressure-sensitive adhesive composition and providing the intermediate layer on the substrate. In this way, the dicing sheet according to the present invention is obtained.

Such a dicing sheet according to the present invention is a case where a cylindrical electrode having a height of 15 μm and a diameter of 15 μm is pasted on a wafer formed in 3 rows and 3 columns at a pitch of 40 μm through the adhesive layer. Further, in the center electrode of the cylindrical electrode formed in 3 rows and 3 columns, the pressure-sensitive adhesive layer does not come into contact with the portion of the electrode having a height of 7.5 μm or less. That is, as shown in FIGS. 2 and 3, the dicing sheet 10 according to the present invention has cylindrical electrodes 20 (20a to 20i) having a height of 15 μm and a diameter of 15 μm arranged at equal intervals in 3 rows and 3 columns at a pitch of 40 μm. In the inner peripheral portion 25 (inside the broken line in FIG. 3) of the formed region (electrode forming region), the pressure-sensitive adhesive layer 1 does not follow between the electrodes 20, and the height of the electrode 20e is 7.5 μm or less. The adhesive layer 1 does not contact. By adjusting the pressure-sensitive adhesive layer so that it does not come into contact with the base portion (portion where the electrode height is 7.5 μm or less) between the cylindrical electrodes having the above dimensions and arrangement as representative examples of the protruding electrode, The effect of the present invention that the pressure-sensitive adhesive layer hardly follows between the electrodes of the electrode can be obtained. Such characteristics are adjusted by adjusting the storage elastic modulus G ′ at 23 ° C. of the intermediate layer and the adhesive layer at the time of application to a predetermined range in the dicing sheet having the adhesive layer and the intermediate layer having a specific thickness. Is possible.
Further, the adhesive layer 1 follows the electrode 20 and adheres to the wafer 30 at the outer peripheral portion 26 (outside the broken line in FIG. 3) of the electrode formation region. For this reason, the penetration | invasion of the water at the time of dicing is prevented, it is excellent in dicing property, and generation | occurrence | production of chipping can be prevented. Moreover, since the adhesive force can be controlled by curing the pressure-sensitive adhesive layer 1 with energy rays, the chip can be easily picked up and the chip can be prevented from being damaged.
Note that the dicing sheet of the present invention is attached to the wafer at the time of evaluation of the above characteristics under the conditions of 23 ° C., an application pressure of 0.3 MPa, and an application speed of 5 mm / second.

  The dicing sheet according to the present invention is preferably used for being attached to a surface on which an electrode of a semiconductor wafer having protruding electrodes is formed. Examples of the protruding electrode include a cylindrical electrode and a spherical electrode. The dicing sheet according to the present invention can be suitably used particularly for a wafer having a through electrode that has been increasingly used in recent years. The method for attaching the dicing sheet to the semiconductor wafer is not particularly limited.

  Next, using a cutting means such as a dicing blade, the semiconductor wafer is separated into individual circuits to produce semiconductor chips. The cutting depth at this time is a depth that takes into account the total thickness of the semiconductor wafer, the thickness of the adhesive layer and the intermediate layer, and the wear of the dicing blade.

  After dicing, the dicing sheet according to the present invention is expanded as necessary to separate the intervals between the semiconductor chips, and then the semiconductor chips are picked up by general-purpose means such as a suction collet. The Further, it is preferable to perform expansion and pickup after irradiating the pressure-sensitive adhesive layer with energy rays to reduce the adhesive strength.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. “Followability”, “dicing property”, “pickup property”, “residue of adhesive layer” and “storage modulus G ′” in the following examples and comparative examples were evaluated as follows.

<Followability>
A dicing sheet is placed on one side of a silicon wafer (8 inches in diameter and 50 μm in thickness) formed by projecting cylindrical electrodes (height 15 μm, diameter 15 μm) on both sides at regular intervals with a pitch of 40 μm in 3 rows and 3 columns. Pasting (23 ° C., pasting pressure 0.3 MPa, pasting speed 5 mm / second) was performed. Next, using a UV irradiation device (RAD-2000m / 12 manufactured by Lintec Corporation), UV irradiation was performed in a nitrogen atmosphere (illuminance 230 mW / cm ² , light amount 190 mJ / cm ² ) to cure the pressure-sensitive adhesive layer. After peeling the dicing sheet from the wafer, the center of the mark of the columnar electrode in the first row and first column (columnar electrode 20a in FIG. 3) and the columnar electrode in the third row and third column (column 20i in FIG. 3). The peeled dicing sheet was cut along a straight line connecting the centers of the traces of the mold electrode). The cut surface was observed using a digital microscope, and the difference in distance from the wafer surface between the point where the top of the cylindrical electrode was in contact and the point where the adhesive layer was closest to the wafer surface was determined. By checking whether or not it was smaller than 7.5 μm, it was determined whether or not the pressure-sensitive adhesive layer was in contact with a portion of the cylindrical electrode having a height of 7.5 μm or less.
When the pressure-sensitive adhesive layer does not follow between the cylindrical electrodes (when the pressure-sensitive adhesive layer is not in contact with the portion of the electrode height of 7.5 μm or less), “A”, and when the pressure-sensitive adhesive layer follows between the cylindrical electrodes Rated “B”.

<Dicing property>
A silicon wafer is diced to obtain chips, and the end portions of the ten chips are observed, and the case where there is no chipping (chip chipping) larger than 30 μm at the ends is “A”, more than 30 μm and less than 50 μm The case where there was chipping was evaluated as “B”, and the case where there was chipping larger than 50 μm was evaluated as “C”. The dicing conditions are as follows.

Dicing conditions A dicing sheet is pasted on one side of a silicon wafer (diameter 8 inches, thickness 50 μm) on which cylindrical electrodes (height 15 μm, diameter 15 μm) are formed on both sides (23 ° C., pasting pressure 0.3 MPa, pasting speed 5 mm) / Second). The silicon wafer was diced using a dicing apparatus (DFD651 manufactured by Disco Corporation) at a cutting speed of 20 mm / min and a cutting depth of the dicing sheet into the substrate of 20 μm to obtain a chip (size: 5 mm × 5 mm). A dicing blade (27HECC) manufactured by Disco Corporation was used as the dicing blade, and the rotation speed of the blade was set to 40000 rpm. Further, the cylindrical electrodes were formed at equal intervals with a pitch of 40 μm, and 400 pieces per 1 mm ² .

<Pickup property>
A silicon wafer was diced to obtain a chip, and ultraviolet rays were irradiated under a nitrogen atmosphere (illuminance 230 mW / cm ² , light amount 190 mJ / cm ² ) using an ultraviolet irradiation device (RAD-2000m / 12 manufactured by Lintec Corporation). Next, the chip was picked up using a pickup device (BESTEM D02 manufactured by Canon Machinery Co., Ltd.). The case where the chip could be picked up was evaluated as “A”, and the case where the chip could not be picked up was evaluated as “B”. The dicing conditions are as described above.

<Residue of adhesive layer>
The surface of the chip after pick-up was observed, and the presence or absence of a residue of the pressure-sensitive adhesive layer was confirmed between the cylindrical electrodes and at the outer periphery of the cylindrical electrode forming region. The case where no residue was generated was evaluated as “A”, the case where a residue was slightly generated was evaluated as “B”, and the case where a residue was generated was evaluated as “C”.

<Storage elastic modulus G '>
The storage elastic modulus G ′ at 23 ° C. of the intermediate layer and the pressure-sensitive adhesive layer before curing was measured with a dynamic viscoelastic device (RDAII manufactured by Rheometrics) at a frequency of 1 Hz and a twist amount of 0.5%.

Example 1
[Preparation of pressure-sensitive adhesive composition]
Acrylic adhesive polymer obtained by reacting butyl acrylate / methyl methacrylate / 2-hydroxyethyl acrylate = 62/10/28 (mass ratio), and 30.2 g (acrylic adhesive property) per 100 g of the acrylic adhesive polymer 100 parts by mass of an energy ray-curable adhesive polymer (weight average molecular weight: 600,000) obtained by reacting methacryloyloxyethyl isocyanate (MOI) of 80 mol per 100 mol of 2-hydroxyethyl acrylate unit of the polymer. , 3 parts by mass of a photopolymerization initiator (α-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.)) and 8.6 masses of a crosslinking agent (polyvalent isocyanate compound (Coronate L manufactured by Nippon Polyurethane Co., Ltd.)) Part in a solvent and adhesive group A composition was obtained. The weight average molecular weight is measured using a commercially available molecular weight measuring instrument (main product name “HLC-8220GPC”, manufactured by Tosoh Corporation; column product name “TSKGel SuperHZM-M”, manufactured by Tosoh Corporation; developing solvent tetrahydrofuran). (The same applies hereinafter). Moreover, even if a mass part is a thing of the packing form diluted with a solvent, all are values of solid content conversion (hereinafter, the same).

[Preparation of intermediate layer composition]
Polypropylene glycol having a molecular weight of 4000 calculated from the hydroxyl value (hereinafter referred to as PPG4000) and isophorone diisocyanate (hereinafter referred to as IPDI) are polymerized to PPG4000 / IPDI = 6/7 (mass ratio) to obtain a weight average molecular weight of 50,000. A urethane oligomer was obtained. The weight average molecular weight was measured using a commercially available molecular weight measuring instrument (main product name “HLC-8220GPC”, manufactured by Tosoh Corporation; column product name “TSKGel SuperHZM-M”, manufactured by Tosoh Corporation; developing solvent tetrahydrofuran). It is the value obtained by using (hereinafter the same).

  100 parts by mass (solid content) of the obtained urethane oligomer, 90 parts by mass (solid content) of isobornyl acrylate as an energy ray curable monomer, 50 parts by mass (solid content) of 2-hydroxy-3-phenoxypropyl acrylate, and photopolymerization 2.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, solid concentration 100% by mass, manufactured by BASF) as an initiator is added, and a composition as an intermediate layer composition (energy ray curing of room temperature liquid) A mold composition was obtained.

[Production of dicing sheet]
The intermediate layer composition is applied to a release film (SP-PET3811 manufactured by Lintec Corporation) so that the thickness after drying is 15 μm, and irradiated with ultraviolet rays (illuminance 200 mW / cm ² , light quantity 1000 mJ / cm ² ). Cured to obtain an intermediate layer formed on the release film. Next, the intermediate layer and the substrate (ethylene methacrylic acid copolymer film 80 μm thick) were bonded together, the release film was peeled off from the intermediate layer, and the intermediate layer was transferred onto the substrate.

  In addition, the pressure-sensitive adhesive composition was applied to a release film (SP-PET3811 manufactured by Lintec Corporation) and dried (drying conditions: 100 ° C., 1 minute) so that the thickness after drying was 10 μm, and then on the release film. The pressure-sensitive adhesive layer formed was obtained.

  Then, the intermediate | middle layer with a base material and the adhesive layer with a peeling film were bonded together, the peeling film was removed, the dicing sheet was obtained, and each evaluation was performed. The results are shown in Table 1.

(Example 2)
A dicing sheet was obtained in the same manner as in Example 1 except that the thickness of the intermediate layer was 20 μm, and each evaluation was performed. The results are shown in Table 1.

(Example 3)
A dicing sheet was obtained in the same manner as in Example 1 except that the following intermediate layer composition was used and the thickness of the intermediate layer was 20 μm, and each evaluation was performed. The results are shown in Table 1.

[Preparation of intermediate layer composition]
Polymerization of PTMG2000 / IPDI = 5/6 (mass ratio) using polytetramethylene glycol (hereinafter referred to as PTMG2000) having a molecular weight of 2000 calculated from the hydroxyl value and isophorone diisocyanate to obtain a urethane oligomer having a weight average molecular weight of 35,000. It was.

  100 mass parts (solid content) of the obtained urethane oligomer, 80 mass parts (solid content) of isobornyl acrylate as an energy ray-curable monomer, 60 mass parts (solid content) of 2-hydroxy-3-phenoxypropyl acrylate, and photopolymerization Addition of 2.4 parts by mass of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (BASF Darocur 1173, solid concentration 100% by mass) as an initiator, and blending as an intermediate layer composition Product (room temperature liquid energy ray curable composition was obtained.

Example 4
A dicing sheet was obtained in the same manner as in Example 1 except that the following intermediate layer composition was used and the thickness of the intermediate layer was 20 μm, and each evaluation was performed. The results are shown in Table 1.

[Preparation of intermediate layer composition]
At the end of a terminal isocyanate urethane prepolymer obtained by polymerizing polypropylene glycol having a molecular weight of 4000 calculated from the hydroxyl value and hexamethylene diisocyanate (hereinafter referred to as HMDI), 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) is added to PPG4000 / It was made to react by HMDI / HEMA = 5/6/2 (mass ratio), and the urethane (meth) acrylate oligomer whose weight average molecular weight was 40000 was obtained.

  100 parts by mass (solid content) of the obtained urethane (meth) acrylate oligomer, 30 parts by mass of isobornyl acrylate (solid content) as an energy ray-curable monomer, 50 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate (solid content) ) And 1.8 parts by mass of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (BASF Darocur 1173, solid concentration 100% by mass) as a photopolymerization initiator, Formulation as product (room temperature liquid energy ray curable composition was obtained.

(Comparative Example 1)
A dicing sheet was obtained in the same manner as in Example 1 except that no intermediate layer was used, and each evaluation was performed. The results are shown in Table 1.

(Comparative Example 2)
A dicing sheet was obtained and evaluated in the same manner as in Example 1 except that the intermediate layer was not used and the thickness of the pressure-sensitive adhesive layer was 25 μm. The results are shown in Table 1.

(Comparative Example 3)
A dicing sheet was obtained and evaluated in the same manner as in Example 1 except that the following intermediate layer composition was used. The results are shown in Table 1.

[Preparation of intermediate layer composition]
At the end of the terminal isocyanate urethane prepolymer obtained by polymerizing polypropylene glycol having a molecular weight of 4000 calculated from the hydroxyl value and isophorone diisocyanate, 2-hydroxyethyl methacrylate is added to PPG4000 / IPDI / HEMA = 6/7/2 (mass ratio). To obtain a urethane (meth) acrylate oligomer having a weight average molecular weight of 45,000.

  100 parts by mass (solid content) of the urethane (meth) acrylate oligomer obtained, 100 parts by mass (solid content) of isobornyl acrylate as an energy ray-curable monomer, 130 parts by mass (solid content) of 2-hydroxy-3-phenoxypropyl acrylate ) And 3.3 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (BASF's Irgacure 184, solid content concentration 100% by mass) as a photopolymerization initiator, and a composition (room temperature liquid) as an intermediate layer composition The energy ray-curable composition was obtained.

(Comparative Example 4)
A dicing sheet was obtained and evaluated in the same manner as in Example 1 except that the following pressure-sensitive adhesive composition was used. The results are shown in Table 1.

[Preparation of pressure-sensitive adhesive composition]
100 parts by mass of an acrylic polymer (weight average molecular weight: 720,000) obtained by reacting 2-ethylhexyl acrylate / 2-hydroxyethyl acrylate = 88/12 (mass ratio), and a crosslinking agent (polyvalent isocyanate compound ( Nippon Polyurethane Co., Ltd. Coronate L)) 0.6 parts by mass was mixed in a solvent to obtain an adhesive composition.

(Comparative Example 5)
A dicing sheet was obtained and evaluated in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was 40 μm. The results are shown in Table 1.

In the dicing sheets of Comparative Examples 1 and 2, since there was no intermediate layer, the followability of the dicing sheet in the outer peripheral portion of the electrode formation region was low, and a residue of the adhesive layer was generated.
Moreover, in the dicing sheet of Comparative Example 3, since the storage elastic modulus G ′ at 23 ° C. of the intermediate layer was large, the followability of the dicing sheet at the outer peripheral portion of the electrode forming region was low, and a residue of the adhesive layer was generated.
In the dicing sheet of Comparative Example 4, since the storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is small, the pressure-sensitive adhesive layer follows between the electrodes, and a residue of the pressure-sensitive adhesive layer between the electrodes is generated and picked up. There wasn't.
Moreover, in the dicing sheet of Comparative Example 5, since the pressure-sensitive adhesive layer was too thick, the followability of the dicing sheet in the outer peripheral portion of the electrode formation region was insufficient, and a pressure-sensitive adhesive layer residue was generated.

DESCRIPTION OF SYMBOLS 10: Dicing sheet 1: Adhesive layer 2: Intermediate layer 3: Adhesive layer 20 (20a-20i): Cylindrical electrode 30: Semiconductor wafer

Claims (9)

It consists of a base material, an intermediate layer made of a urethane-containing cured product provided on one side thereof, and an adhesive layer having a thickness of 8 to 30 μm provided on the intermediate layer,
The storage elastic modulus G ′ at 23 ° C. of the intermediate layer is 10 ⁴ Pa or more and less than 10 ⁵ Pa,
The pressure-sensitive adhesive layer contains a compound having an energy ray-curable double bond in the molecule,
The storage elastic modulus G ′ at 23 ° C. of the pressure-sensitive adhesive layer is 3 × 10 ⁵ Pa or more,
When a cylindrical electrode having a height of 15 μm and a diameter of 15 μm is pasted through a pressure-sensitive adhesive layer on a wafer in which a cylindrical electrode having a pitch of 40 μm is formed at equal intervals in 3 rows and 3 columns, a cylindrical shape formed in 3 rows and 3 columns A dicing sheet characterized in that, in the electrode at the center of the electrode, the pressure-sensitive adhesive layer does not contact a portion of the electrode having a height of 7.5 μm or less.   The dicing sheet according to claim 1, wherein the intermediate layer is a cured product of a blend containing a urethane oligomer having a weight average molecular weight of 10,000 or more, an energy ray-curable monomer having a molecular weight of less than 1000, and a photopolymerization initiator.   The compound having an energy ray curable double bond in the molecule includes an energy ray curable adhesive polymer in which an energy ray polymerizable group is bonded to the main chain or side chain of the polymer. The dicing sheet described in 1. The pressure-sensitive adhesive layer contains an acrylic polymer having a reactive functional group and a crosslinking agent,
The dicing sheet according to any one of claims 1 to 3, comprising 5 parts by mass or more of a crosslinking agent with respect to 100 parts by mass of the acrylic polymer.   The dicing sheet according to claim 4, wherein the crosslinking agent is an isocyanate-based crosslinking agent.   The dicing sheet according to any one of claims 1 to 5, wherein the dicing sheet is used by being attached to a wafer provided with a protruding electrode.   The dicing sheet according to claim 6, wherein the protruding electrode is a through electrode.   The dicing sheet according to claim 6 or 7, wherein the intermediate layer has a thickness of 0.5 to 1.5 times the height of the protruding electrode. A step of attaching the dicing sheet according to any one of claims 1 to 8 to a surface of a semiconductor wafer having a protruding electrode, wherein the semiconductor wafer is separated into pieces for each circuit to produce a semiconductor chip. A method of manufacturing a semiconductor chip, comprising a step of picking up a semiconductor chip.

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