JP7766465B2 - Laser dicing adhesive tape - Google Patents

Description

The present invention relates to an adhesive tape for laser dicing used to secure a semiconductor wafer when dicing the semiconductor wafer with a laser guided by a water jet.

Traditionally, the blade cut method, in which a dicing blade rotated at high speed is used to dice semiconductor wafers and semiconductor-related materials, has been the norm. With this method, the cutting resistance of the blade is applied directly to the semiconductor wafer during cutting. This cutting resistance can cause individual chips to fly off the adhesive tape holding them in place, or cause defects such as tiny chips and cracks in the chips, reducing the productivity and quality of semiconductor chips. This has become an even more serious problem in recent years due to demand for smaller and thinner electronic devices.

Meanwhile, various dicing methods using laser beams are being investigated as an alternative to the semiconductor wafer cutting technology using a dicing blade, one of which is the laser dicing method, which uses a laser beam guided by a water jet.

When dicing wafers using this method, the cutting resistance of the blade is not directly applied to the wafer as it is with the blade cutting method, which reduces the occurrence of defects such as chipping and cracking. Furthermore, because the wafer is guided by a water jet, it is cooled efficiently, reducing the thermal load.

Laser dicing, in which the laser is guided by a water jet, has the problem that pressure from the water flow is applied to the adhesive surface of the adhesive tape that secures the wafer during dicing, making it easy for the individual chips to peel off from the adhesive tape. To address this issue, Patent Document 1 proposes a water-permeable adhesive tape that uses a supporting substrate with water-permeable perforations to prevent peeling due to the water flow.

However, when a nonwoven fabric or perforated substrate is used as a water-permeable substrate as in Patent Document 1, the perforations may be uneven or the perforation area may not be large, which can make it difficult for water to pass through depending on the chip size and dicing conditions, resulting in chip flying.

In contrast, Patent Document 2 describes how using a mesh substrate as a water-permeable substrate allows the hole size and opening area to be relatively large compared to nonwoven fabric or perforated substrates, stabilizing water permeability and further reducing chipping and chip defects.

However, with a mesh substrate, when picking up the individual chips, the adhesive layer that is not held by the substrate at the opening tends to transfer to the chip, leaving adhesive residue on the chip.

Japanese Patent Application Laid-Open No. 2001-316648 Japanese Patent Application Laid-Open No. 2008-117943

The present invention aims to provide an adhesive tape for laser dicing that prevents chips from flying off or chip defects caused by the water flow during dicing, in which the laser is guided by a water jet, and that prevents the adhesive layer from transferring to the chip side (leaving adhesive residue on the chip) when the individual chips are picked up.

The first invention is an adhesive tape used in laser dicing in which the laser is guided by a water jet, comprising a substrate and an adhesive layer and a separator film laminated in that order on one side of the substrate, the substrate being a mesh substrate having openings formed from fibers, the adhesive layer being made of an adhesive composition containing an acrylic adhesive and a hydroxyl group-containing compound, the hydroxyl group-containing compound having a hydroxyl value of 100 to 400 mgKOH/g and a weight average molecular weight in the range of 140 to 5000, the hydroxyl group-containing compound comprising 10 to 40 mass% of the solid content of the adhesive layer , and the adhesive layer being not a continuous film, and having openings at least at positions that coincide with the openings on the surface of the mesh substrate.

The second invention is the adhesive tape for laser dicing described in the first invention, in which the fiber material forming the mesh substrate is polyester or nylon, and the opening ratio of the mesh substrate is 25% to 75%.

A third invention is the pressure-sensitive adhesive tape for laser dicing according to claim 1 or 2, characterized in that the pressure-sensitive adhesive layer contains a radiation-polymerizable compound, and has an adhesive strength of 1 N/25 mm or more before radiation exposure and an adhesive strength of less than 0.5 N/25 mm after radiation exposure .

By using a mesh substrate as the support substrate, the adhesive tape for laser dicing of the present invention can stably maintain water permeability from the water jet, preventing chips from flying off or chipping during dicing. Furthermore, the adhesive layer is formed on the fiber portion of the mesh substrate and has openings in positions that coincide with the openings on the surface of the mesh substrate. This means that there is no adhesive layer that is not held by the substrate and is likely to transfer to the chip side, making it possible to provide an adhesive tape for laser dicing that does not leave adhesive residue on the chip when the individual chips are picked up.

1 is a cross-sectional schematic view showing one embodiment of the pressure-sensitive adhesive tape for laser dicing of the present invention.

The following describes an embodiment of the present invention.

The adhesive tape for laser dicing of the present invention is composed of a mesh substrate, an adhesive layer, and a separator film laminated in that order. The adhesive layer is not a continuous film, but has openings at positions that coincide with the openings on at least the surface of the mesh substrate (the surface that comes into contact with the adhesive layer).

(Base material)
The substrate constituting the pressure-sensitive adhesive tape for laser dicing of the present invention is a mesh substrate which is a mesh-like woven fabric made of filament yarns. Examples of the woven fabric include plain weave, twill weave, and satin weave, but plain weave is preferred because it has a high binding force between the warp and weft yarns and is therefore excellent in strength.

Examples of fiber materials for filament yarns include synthetic fibers such as polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyurethane, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyamide, acrylic, and nylon, as well as natural fibers such as silk, metals such as stainless steel and brass, and inorganic fibers such as glass and carbon fiber. Of these fiber materials, synthetic fibers are preferred from the perspectives of flexibility and processability, and polyester or nylon are more preferred from the perspectives of transparency to the laser used for dicing and adhesion to adhesives.

These fibers may be either monofilament or multifilament, but monofilament is preferred to ensure uniform mesh opening size. The fiber diameter is preferably approximately 10 to 300 μm, and from the standpoint of water permeability, approximately 25 to 150 μm is more preferred. The mesh opening rate is preferably 15 to 85%, and more preferably 25 to 75%. If the mesh opening rate is below this range, water permeability will be poor and the chips will be more likely to peel off due to water flow. On the other hand, if the opening rate exceeds this range, the adhesive tape of the present invention will have openings in the adhesive layer at positions that coincide with the openings on the surface of the mesh substrate, reducing the contact area between the adhesive layer and the chips and making the chips more likely to peel off.

The thickness of the substrate is preferably 10 to 400 μm, more preferably 30 to 250 μm, from the viewpoints of the processability and handling of the adhesive tape, and the resistance to breakage and cutting during dicing.

If necessary, the surface of the substrate on which the adhesive layer is to be laminated may be subjected to surface treatment such as corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or primer treatment.

(Adhesive layer)
The adhesive composition used in the adhesive layer of the laser dicing adhesive tape of the present invention can be any commonly used acrylic adhesive or radiation-curable adhesive. It is particularly preferable to use a radiation-curable adhesive, which reduces adhesive strength upon irradiation and facilitates peeling. Radiation-curable adhesives generally consist of an acrylic adhesive and a radiation-polymerizable compound. Furthermore, a hydroxyl group-containing compound is blended into the adhesive composition to form openings in the adhesive layer at positions that coincide with the openings in the surface of the mesh substrate. This allows the adhesive layer composition to collect in the fiber portion of the mesh substrate during curing and aging of the adhesive layer, forming openings in the adhesive layer at positions that coincide with the openings in the surface of the mesh substrate.

Acrylic adhesives contain a (meth)acrylic copolymer and a curing agent as essential ingredients. (Meth)acrylic copolymers can be obtained, for example, by copolymerizing one or more (meth)acrylic acid alkyl esters in which the alkyl group has 4 to 18 carbon atoms with one or more other copolymerizable monomers containing an ethylenically unsaturated bond using conventional methods.

Examples of the (meth)acrylic acid alkyl ester include n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

Examples of the copolymerizable monomer having an ethylenically unsaturated bond include acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, cyclohexyl (meth)acrylate, styrene, α-methylstyrene, vinyl acetate, N-vinyl-2-pyrrolidone, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, acrylic acid, methacrylic acid, itaconic acid, and fumaric acid.

In the (meth)acrylic copolymer, a monomer having a functional group that can react with the curing agent described below is used as an essential component as a monomer having a copolymerizable ethylenically unsaturated bond. As the monomer having a functional group, particularly preferred are monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

The weight-average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 10,000 to 1,000,000, and more preferably 200,000 to 800,000. If the weight-average molecular weight is outside this range, problems such as reduced adhesive strength and reduced susceptibility to thermal decomposition may occur. The weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

The curing agent is used to adjust the adhesive strength and cohesive strength by reacting with the functional groups of the (meth)acrylic copolymer. Examples of curing agents include isocyanate-based curing agents, epoxy-based curing agents, and metal chelate-based curing agents. However, when the functional group is a hydroxyl group, an isocyanate-based curing agent is preferred.

Examples of isocyanate-based curing agents include polyisocyanate, polyisocyanate trimers, urethane prepolymers having isocyanate groups at their termini obtained by reacting polyisocyanate with polyols, and polyisocyanate compounds having two or more isocyanate groups per molecule, such as trimers of such urethane prepolymers.

Examples of polyisocyanates include 2,4-tolylene diisocyanate, 2,5-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate. Curing agents may be used alone or in combination of two or more.

The amount of curing agent added can be adjusted appropriately depending on the required adhesive strength, and is typically 0.01 to 30 parts by mass, more preferably 0.1 to 15.0 parts by mass, per 100 parts by mass of the (meth)acrylic copolymer.

The radiation-polymerizable compound used in the radiation-curable adhesive is, for example, a low-molecular-weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule that can be three-dimensionally reticulated by irradiation with light. Specific examples that can be widely used include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and oligoester acrylate.

In addition to the acrylate compounds mentioned above, urethane acrylate oligomers can also be used. Urethane acrylate oligomers are obtained by reacting a terminated isocyanate urethane prepolymer obtained by reacting a polyester or polyether polyol compound with a polyisocyanate compound (e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc.), with an acrylate or methacrylate containing a hydroxyl group (e.g., 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.).

The blending ratio of the acrylic adhesive to the radiation-polymerizable compound in the radiation-curable adhesive is preferably 10 to 200 parts by weight, more preferably 20 to 120 parts by weight, of the radiation-polymerizable compound per 100 parts by weight of the acrylic adhesive. Outside this range, problems such as difficulty in reducing adhesive strength and increased likelihood of adhesive residue may occur. Furthermore, instead of blending a radiation-polymerizable compound into the acrylic adhesive as described above, the acrylic adhesive itself can also be a radiation-polymerizable acrylic ester copolymer.

It is also preferable to incorporate a radiation-polymerization initiator into the radiation-curable adhesive. Examples of radiation-polymerization initiators include isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxymethylphenylpropane. Adding at least one of these to the adhesive layer allows the polymerization reaction to proceed efficiently. Note that radiation here refers to light rays such as ultraviolet rays, or ionizing radiation such as electron beams.

The amount of radiation polymerization initiator added is typically 0.05 to 15 parts by mass, and preferably 0.2 to 10 parts by mass, per 100 parts by mass of radiation-curable adhesive.

In addition to the acrylic adhesive or radiation-curable adhesive components, the adhesive composition forming the adhesive layer of the present invention contains a hydroxyl-containing compound to improve adhesion between the adhesive layer and the mesh substrate and to form openings in the adhesive layer at positions that coincide with the openings in the surface of the mesh substrate. By incorporating a hydroxyl-containing compound into the adhesive composition, adhesion between the adhesive layer and the fibers of the mesh substrate is improved. Even if adhesion is reduced by the use of a radiation-curable adhesive, adhesion between the adhesive layer and the substrate can be ensured, preventing transfer of the adhesive layer to the chip. Furthermore, the hydroxyl-containing compound has the effect of increasing the interfacial tension of the adhesive layer coating. When a separator film is laminated and the adhesive layer is cured and aged, the uncured adhesive layer migrates to the fiber portions of the mesh substrate, forming an adhesive layer in the fiber portions and forming openings in the adhesive layer at positions that coincide with the openings in the surface of the mesh substrate.

Hydroxyl group-containing compounds include acrylic, polyester, and polyether compounds, but acrylic compounds are preferred due to the ease of introducing polyfunctional hydroxyl groups and polymer design.

Examples of hydroxyl group-containing acrylic compounds include (meth)acrylic acid ester monomers that have one or more hydroxyl groups in the molecule, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 2,2-dihydroxymethylbutyl (meth)acrylate, polyhydroxyalkyl maleate, and polyhydroxyalkyl fumarate, as well as copolymers obtained by copolymerizing the above-mentioned (meth)acrylic acid ester monomers with other monomers that are copolymerizable with them.

Examples of the copolymerizable monomer include (meth)acrylic acid, alkyl (meth)acrylate (C1 to C12), maleic acid, alkyl maleate, fumaric acid, alkyl fumarate, itaconic acid, alkyl itaconate, styrene, α-methylstyrene, vinyl acetate, (meth)acrylonitrile, 3-(2-isocyanate-2-propyl)-α-methylstyrene, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Hydroxyl group-containing acrylic compounds can be obtained by copolymerizing these monomers in the presence of a suitable solvent and polymerization initiator.

Examples of hydroxyl group-containing polyester compounds include hydroxyl group-containing polyester compounds obtained by condensation polymerization of polyhydric alcohols and polybasic acids, and hydroxyl group-containing polyester compounds obtained by ring-opening polymerization of lactones.

Examples of polyhydric alcohols used in the condensation polymerization to obtain the hydroxyl group-containing polyester compound include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, tetramethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, 1,3-dihydroxyacetone, hexylene glycol, 1,2,6-hexanetriol, ditrimethylolpropane, mannitol, sorbitol, and pentaerythritol.

Examples of polybasic acids used in the condensation polymerization to obtain the hydroxyl group-containing polyester compound include oxalic acid, adipic acid, sebacic acid, fumaric acid, malonic acid, succinic acid, glutaric acid, azelaic acid, citric acid, 2,6-naphthalenedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, citraconic acid, 1,10-decanedicarboxylic acid, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, and trimellitic anhydride.

Examples of lactones used in ring-opening polymerization to obtain the hydroxyl group-containing polyester compound include ε-caprolactone, δ-valerolactone, and γ-butyrolactone.

Examples of hydroxyl group-containing polyether compounds include hydroxyl group-containing polyether compounds obtained by the addition reaction of cyclic ether compounds to polyhydric alcohols, and hydroxyl group-containing polyether compounds obtained by ring-opening polymerization of alkylene oxides.

The hydroxyl value of the hydroxyl group-containing compound is preferably in the range of 50 to 500 mgKOH/g, more preferably 100 to 400 mgKOH/g. If the hydroxyl value is below this range, it becomes difficult to increase the interfacial tension of the adhesive layer coating, making it difficult to transfer the adhesive layer to the fiber portion of the mesh substrate and form openings in the adhesive layer. Furthermore, adhesion to the support substrate decreases, making the adhesive layer more likely to peel from the substrate. On the other hand, if the hydroxyl value exceeds this range, adhesive performance decreases.

The weight-average molecular weight of the hydroxyl group-containing compound is preferably in the range of 140 to 8,000, more preferably 140 to 5,000. If the weight-average molecular weight is below this range, low-molecular-weight components will migrate to the adherend. On the other hand, if it exceeds this range, the fluidity of the adhesive layer coating will decrease, making it difficult to transfer the adhesive layer to the fiber portions of the mesh substrate and form openings in the adhesive layer.

The amount of the hydroxyl group-containing compound is 5 to 50% by mass, more preferably 10 to 40% by mass, of the solid content of the adhesive layer. If the amount is less than this range, it becomes difficult to increase the interfacial tension of the adhesive layer coating, making it difficult to transfer the adhesive layer to the fiber portion of the mesh substrate and form openings in the adhesive layer. On the other hand, if the amount exceeds this range, adhesive performance will decrease.

The adhesive layer of the present invention may contain various additives such as antioxidants, antistatic agents, leveling agents, and antifoaming agents, as needed.

The coating weight of the adhesive layer is about 5 to 50 g/m2, more preferably 10 to 30 g/ ^m2 , in order to ensure adhesion and holding power to the adherend, and to form the adhesive layer on the fiber portion of the mesh substrate and create a structure in which the adhesive layer has openings. If the coating weight of the adhesive layer is less than 5 g/ ^{m2 ,} depending on the adhesive strength to the adherend, the holding power in the shear direction cannot be ensured, and the adhesive layer is likely to peel from the adherend. Furthermore, if the coating weight of the adhesive layer exceeds 50 g/ ^m2 , the volume of the adhesive composition increases, making it difficult to form openings in the adhesive layer.

The method for forming the adhesive layer of the present invention involves uniformly applying the adhesive composition, either as is or as a coating liquid with the viscosity adjusted with a solvent or the like, to a release-treated surface of a separator to a predetermined thickness, and then drying the solvent to form an adhesive layer. A mesh substrate is then bonded to the surface of the adhesive layer, and the resulting layer is cured and aged at room temperature or a predetermined temperature, causing the adhesive layer to migrate to the fiber portions of the mesh substrate, forming openings in the adhesive layer at positions that coincide with the openings in the surface of the mesh substrate.

Examples of methods for applying the coating liquid for the pressure-sensitive adhesive layer of the present invention include gravure coaters, bar coaters, comma knife coaters, die coaters, and reverse coaters.

The adhesive strength of the adhesive tape of the present invention is 1 N/25 mm or more, more preferably 2 N/25 mm or more. If the adhesive strength is low, the diced chips tend to peel easily. Furthermore, when a radiation-curable adhesive is used, the adhesive strength after radiation exposure is preferably less than 1 N/25 mm, and even more preferably less than 0.5 N/25 mm. Lower adhesive strength can reduce defects such as chipping during pickup. Here, adhesive strength is the value measured when the peel force against the mirror surface of a silicon wafer is measured under conditions of a measurement temperature of 23±3°C, a peel angle of 180°, and a peel speed of 300 mm/min.

(separator film)
The pressure-sensitive adhesive tape of the present invention has a structure in which a separator film, one side of which has been subjected to a release treatment, is laminated on a pressure-sensitive adhesive layer. The separator film is peeled off when the pressure-sensitive adhesive tape is used.

As mentioned above, the adhesive layer is formed on the release-treated surface of a release-treated separator film, and the mesh substrate is then bonded to the adhesive layer surface and cured and aged. However, the adhesive layer coating formed on the release-treated surface before curing flows due to the interaction between its own high interfacial tension and the low interfacial tension of the release-treated surface, and moves to the fiber part of the mesh substrate, allowing openings in the adhesive layer to be formed at positions that coincide with the openings in the surface of the mesh substrate.

The separator film may be made of synthetic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, or polyurethane, with polyethylene terephthalate film being preferred from the standpoint of heat resistance and strength. The thickness of the separator film is typically about 6 to 200 μm, with about 12 to 100 μm being more preferable from the standpoint of handleability and cost.

The release agent used in the release treatment of the separator film can be any conventional release agent, such as a silicone-based release agent, a long-chain alkyl-based release agent, or a fluorine-based release agent. Of these, it is preferable to use a silicone-based release agent, which is relatively inexpensive and provides stable release properties.

A suitable silicone release agent is a thermosetting silicone release agent. For example, a thermosetting silicone release agent can be one that cures a silicone composition consisting of a polyorganosiloxane with two or more alkenyl groups per molecule and an organohydrogenpolysiloxane as a crosslinker through an addition reaction. Furthermore, a release control agent such as MQ resin can be added to a thermosetting silicone release agent, if necessary.

Heat-curable silicone release agents typically use a platinum catalyst as the curing catalyst. Examples of platinum catalysts include chloroplatinic acid, platinum olefin complexes, and chloroplatinic acid olefin complexes.

From the standpoint of releasability and thickness stability, the thickness of the release treatment is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, and even more preferably 0.1 to 1 μm.

The adhesive tape for laser dicing of the present invention will be described in detail below using examples and comparative examples, but the present invention is not limited to these examples.

<Preparation of Separator Film 1>
A release agent coating liquid prepared by mixing 95 parts by mass of a silicone release agent (KS-776A manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts by mass of a crosslinking agent (CAT.PL-50T manufactured by Shin-Etsu Chemical Co., Ltd.), and 500 parts by mass of toluene was applied to one side of a 38 μm thick polyethylene terephthalate film using a gravure coater so that the dry weight would be 0.3 g/ ^m2 , and the film was then dried and cured in a gear oven at 140°C for 1 minute to form a silicone release-treated layer, and separator film 1 was obtained.

<Adhesive tape substrate to be used>
[Mesh substrate 1]: nylon fiber, monofilament, plain weave, fiber diameter: 100 μm, mesh size: 150 μm, opening ratio: 36%
[Mesh substrate 2]: nylon fiber, monofilament, plain weave, fiber diameter: 100 μm, mesh size: 100 μm, opening ratio: 25%
[Mesh substrate 3]: nylon fiber, monofilament, plain weave, fiber diameter: 40 μm, mesh size: 260 μm, opening ratio: 75%
[Mesh substrate 4]: Polyester fiber, monofilament, plain weave, fiber diameter: 48 μm, mesh size: 140 μm, opening ratio: 55%
The opening ratio of the mesh substrate is a value calculated using the following formula.
Opening rate = (opening size) ² ÷ (opening size + fiber diameter) ²

<Preparation of Pressure-Sensitive Adhesive Layer Coating Solution>
Pressure-sensitive adhesive layer coating solutions 1 to 7 were prepared according to the formulations in Table 1 using the acrylic copolymer, curing agent, radiation-polymerizable compound, photopolymerization initiator, and hydroxyl group-containing compound shown below.
[Acrylic copolymer]: ethyl acetate solution (non-volatile content 50%) of a copolymer of n-butyl acrylate and 2-hydroxyethyl acrylate (weight average molecular weight 600,000, hydroxyl value 20 mgKOH/g)
[Curing agent]: Ethyl acetate solution of tolylene diisocyanate-trimethylolpropane (TMP) adduct (non-volatile content 75%)
[Radiation polymerizable compound]: urethane acrylate oligomer (acrylate hexafunctional, weight average molecular weight 2,000)
[Photopolymerization initiator]: 1-hydroxycyclohexyl phenyl ketone [Hydroxyl group-containing compound A]: copolymer of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate (weight average molecular weight 2,500, hydroxyl value 120 mgKOH/g)
[Hydroxyl group-containing compound B]: 4-hydroxybutyl acrylate (molecular weight 144, hydroxyl value 389 mgKOH/g)
[Hydroxyl group-containing compound C]: n-butyl acrylate and 2-hydroxyethyl acrylate copolymer (weight average molecular weight 5,000, hydroxyl value 200 mgKOH/g)

Example 1
Adhesive layer coating solution 1 was applied to the silicone release-treated surface of separator film 1 so that the coating amount of the adhesive layer after drying would be 15 g/ ^m2 , and after the solvent was dried by heating, mesh substrate 1 was attached to the adhesive layer surface and cured and aged at 45°C for 48 hours to obtain an adhesive tape.

Example 2
An adhesive tape was obtained in the same manner as in Example 1, except that mesh substrate 2 was used instead of mesh substrate 1 to be attached to the adhesive layer.

Example 3
An adhesive tape was obtained in the same manner as in Example 1, except that mesh substrate 3 was used instead of mesh substrate 1 to be attached to the adhesive layer.

Example 4
An adhesive tape was obtained in the same manner as in Example 1, except that mesh substrate 1 to be attached to the adhesive layer was changed to mesh substrate 4.

Example 5
An adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer coating solution 1 in Example 1 was changed to adhesive layer coating solution 2.

Example 6
An adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer coating solution 1 in Example 1 was changed to adhesive layer coating solution 3.

Example 7
An adhesive tape was obtained in the same manner as in Example 1, except that adhesive layer coating solution 1 in Example 1 was changed to adhesive layer coating solution 4.

(Example 8)
An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating solution 1 in Example 1 was changed to the adhesive layer coating solution 5.

Example 9
An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating solution 1 in Example 1 was changed to the adhesive layer coating solution 6.

(Comparative Example 1)
An adhesive tape was obtained in the same manner as in Example 1, except that the adhesive layer coating solution 1 in Example 1 was changed to the adhesive layer coating solution 7.

<Confirmation of the laminated state of the adhesive layer>
A 3 cm square sample was cut out from each of the pressure-sensitive adhesive tapes obtained in Examples 1 to 9 and Comparative Example 1, the separator film was peeled off, and the surface condition of the pressure-sensitive adhesive layer was observed at five points using a microscope (50x magnification). The observation results are shown in Table 2, with an "O" indicating that the pressure-sensitive adhesive layer also had openings at positions that coincided with the openings on the surface of the mesh substrate, and an "X" indicating that the pressure-sensitive adhesive layer was laminated as a continuous film over the entire surface of the mesh substrate.

<Evaluation of chip flying during dicing>
Using each of the pressure-sensitive adhesive tapes of Examples 1 to 9 and Comparative Example 1, a silicon wafer was diced under the following processing conditions, and chipping during processing was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2.
(Processing conditions)
Processing machine: SYNOVA laser microjet dicing device
Dicing speed: 100 mm/s
Water jet diameter: 50 μm
Water jet pressure: 40 MPa
Laser wavelength: 532 nm
Wafer size: 6 inches Wafer thickness: 100 μm
Chip size: 0.6 mm x 0.6 mm
(Evaluation criteria)
◎: Chip flying rate is 0% to less than 0.1% ○: Chip flying rate is 0.1% to less than 3% ×: Chip flying rate is 3% or more

<Evaluation of adhesive residue on chips>
After dicing the silicon wafer under the above conditions, the adhesive tape was irradiated with UV (ultraviolet light) from the substrate side (high-pressure mercury lamp, output 120 W/cm, cumulative light intensity 500 mJ/ ^cm2 ), and 100 individual chips were peeled off from the adhesive tape. The adhesive residue (transfer of the adhesive layer) on the backside of the chip was visually confirmed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 2.
(Evaluation criteria)
◎: No glue residue on any chips ○: 1-2 chips with glue residue ×: 3 or more chips with glue residue

<Confirmation of peeling force from silicon wafer before and after UV irradiation>
Two samples measuring 25 mm wide and 120 mm long were cut out from each of the pressure-sensitive adhesive tapes of Examples 1 to 9 and Comparative Example 1, the separator film was peeled off from the cut samples, and the pressure-sensitive adhesive layer surface was attached to the mirror surface of a Canosis silicon wafer. The adhesive tape substrate was then pressed back and forth once with a 2 kgf rubber roller to produce two samples for each pressure-sensitive adhesive tape. One of the two samples for peel force measurement for each pressure-sensitive adhesive tape was left to stand for 30 minutes at a temperature of 23±3°C and a humidity of 50±5% RH, and then the attached pressure-sensitive adhesive tape was peeled off using a tensile tester at a peel angle of 180° and a peel speed of 300 mm/min, and the peel force from the silicon wafer before UV irradiation was measured. The other tape was left to stand for 30 minutes at a temperature of 23±3°C and a humidity of 50±5% RH, and then UV light (high-pressure mercury lamp, output 120 W/cm, cumulative light intensity 500 mJ/ ^cm2 ) was irradiated from the substrate side of the attached adhesive tape.The attached adhesive tape was then peeled off using a tensile tester at a peel angle of 180° and a peel speed of 300 mm/min to measure the peel strength from the silicon wafer after UV irradiation.The peel strength of each adhesive tape from the silicon wafer before and after UV irradiation is shown in Table 2.

1: Laser dicing adhesive tape 2: Mesh substrate 2a: Fiber portion of mesh substrate 2b: Opening of mesh substrate 3a: Adhesive layer 3b: Opening of adhesive layer 4: Separator film

Claims (3)

1. An adhesive tape for laser dicing, in which a laser is guided by a water jet, comprising a substrate and a pressure-sensitive adhesive layer and a separator film laminated in this order on one side of the substrate, the substrate being a mesh substrate having openings formed from fibers, the pressure-sensitive adhesive layer being made of a pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive and a hydroxyl group-containing compound, the hydroxyl group-containing compound having a hydroxyl value of 100 to 400 mgKOH/g and a weight-average molecular weight of 140 to 5000, the hydroxyl group-containing compound comprising 10 to 40 mass% of the solid content of the pressure-sensitive adhesive layer , and the pressure-sensitive adhesive layer being not a continuous film and having openings at least at positions that coincide with the openings on the surface of the mesh substrate. The adhesive tape for laser dicing according to claim 1, wherein the fiber material forming the mesh substrate is polyester or nylon, and the mesh substrate has an opening ratio of 25% to 75%. 3. The adhesive tape for laser dicing according to claim 1, wherein the adhesive layer contains a radiation-polymerizable compound and has an adhesive strength of 1 N/25 mm or more before radiation exposure and an adhesive strength of less than 0.5 N/25 mm after radiation exposure .