JP3255741B2 - Wafer dicing method, radiation irradiation apparatus used for this method, and pressure-sensitive adhesive sheet for attaching a wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer dicing method, a radiation irradiating apparatus used in the method, and an adhesive sheet for attaching a wafer.

[0002]

BACKGROUND OF THE INVENTION Semiconductor wafers of silicon, gallium arsenide and the like are manufactured in a large diameter state, and this wafer is cut and separated (diced) into element pieces and then transferred to the next step, a mounting step. . At this time, each step of dicing, washing, drying, expanding, pickup, and mounting is added to the semiconductor wafer in a state of being pasted on the adhesive sheet in advance.

[0003] Such an adhesive sheet used in the steps from the dicing step to the pick-up step of a semiconductor wafer has a sufficient adhesive force to the wafer chip from the dicing step to the drying step, and the wafer is picked up during the pick-up. It is desired that the chip has such an adhesive strength that an adhesive does not adhere to the chip.

[0004] Such an adhesive sheet is disclosed in
0-196,956 and JP-A-60-223,
No. 139, a pressure-sensitive adhesive sheet coated with a pressure-sensitive adhesive comprising a low molecular weight compound having at least two or more photopolymerizable carbon-carbon double bonds in a molecule, which can be three-dimensionally reticulated by light irradiation, on a substrate surface. Proposed. These proposals are pressure-sensitive adhesive tapes in which a radiation-curable pressure-sensitive adhesive is applied on a radiation-transparent substrate, and the radiation-curable compound contained in the pressure-sensitive adhesive is cured by irradiation with radiation to form a three-dimensional net-like adhesive. It is based on the principle that a fluidized structure is provided to significantly reduce its fluidity.

[0005] The conventional pressure-sensitive adhesive sheet as exemplified above has the following problems, particularly in the expanding step. The expanding step is a step of widening the interval between the diced element pieces (chips) and facilitating chip pickup. When the conventional adhesive sheet for attaching a wafer is used, there is a difference between an extension rate (expansion rate) of a portion where the wafer is attached and an extension rate of a portion where the wafer is not attached. It was difficult to get the spacing. That is, since the expansion rate of the portion where the wafer is attached is smaller than the expansion rate of the portion where the wafer is not attached, in the expanding step, the portion where the wafer is not attached is preferentially extended. And
The portion to which the wafer was attached did not extend much, and it was necessary to expand excessively in order to obtain a sufficient chip interval. In addition, due to the above-mentioned problems, the substrate used may be limited.

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2-265258 discloses that an adhesive is applied only to a surface portion of a base material to which a wafer is to be adhered, and only to that portion. A dicing apparatus capable of performing ultraviolet irradiation is disclosed. However, this method has a large number of steps and its effect is not sufficient.

JP-A-1-251737 discloses a radiation-curable acrylic pressure-sensitive adhesive provided on a sheet-like substrate, and the pressure-sensitive adhesive layer is cured in a pattern by irradiation with radiation to fix a semiconductor wafer. An adhesive sheet is disclosed. According to the description of this publication, radiation irradiation is performed prior to wafer attachment, and the process is completely different from that of the present invention as described below.

The present inventors have conducted intensive studies in view of the prior art as described above. As a result, if the pressure-sensitive adhesive layer was partially cured at the portion where the wafer was attached, the wafer was attached. It has been found that a desired chip interval can be obtained without excessively expanding in order to prevent a large decrease in the elongation rate of the portion where the cracks have occurred.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has a difference between an expansion ratio of a portion to which a wafer is attached and an expansion ratio of a portion to which no wafer is attached. It is an object of the present invention to solve the above problem in the expanding step caused by the above. Another object of the present invention is to increase the material margin of the base material by solving the above problems.

[0010]

SUMMARY OF THE INVENTION A wafer dicing method according to the present invention comprises:
The wafer adhered on the adhesive layer of the adhesive sheet for attaching a wafer, which has a base material and an adhesive layer whose adhesive strength decreases when irradiated with radiation, is cut and separated into element pieces, and the adhesive is applied. When irradiating the pressure-sensitive adhesive layer with radiation when irradiating the pressure-sensitive adhesive layer to reduce the adhesive force of the pressure-sensitive adhesive layer by irradiating the layer, expanding the sheet to expand the element interval, and picking up element pieces, Irradiation is performed in a pattern on the adhesive layer to which the wafer is attached so that the adhesive layer has substantially the same shape as the attached wafer, and radiation is applied to the entire surface of the adhesive layer where the wafer is not attached. It is characterized by irradiation.

The above-mentioned wafer dicing method according to the present invention can be specifically carried out by using the following radiation irradiating apparatus or wafer-adhering adhesive sheet according to the present invention.

[0012] A radiation irradiation apparatus according to the present invention comprises:
The wafer adhered on the adhesive layer of the adhesive sheet for wafer attachment having an adhesive layer whose adhesive strength is reduced when irradiated with radiation is cut and separated into element pieces, and the adhesive layer is exposed to radiation. Irradiation to reduce the adhesive force of the pressure-sensitive adhesive layer, expand the sheet, expand the element spacing, a radiation irradiation apparatus used for wafer dicing to pick up element small pieces, the radiation generating unit of the apparatus A filter having a radiation attenuating portion having a pattern of substantially the same shape as the attached wafer is provided between the substrate and the adhesive sheet for attaching the wafer.

The pressure-sensitive adhesive sheet for attaching a wafer according to the present invention comprises:
It is characterized by comprising a substrate and a radiation-curable pressure-sensitive adhesive layer provided thereon, wherein a radiation-attenuating portion in a pattern is provided on at least one surface of the substrate.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the wafer dicing method according to the present invention, a radiation irradiating apparatus used for the dicing method and an adhesive sheet for attaching a wafer will be described more specifically.

In the wafer dicing method according to the present invention, an adhesive sheet for attaching a wafer, comprising a substrate and an adhesive layer whose adhesive strength is reduced when irradiated with radiation, is used. This adhesive layer polymerizes and cures when irradiated with radiation,
Since the adhesive strength is reduced, it is possible to easily pick up the attached element pieces and the like.

In the present invention, a wafer to be cut is attached to the pressure-sensitive adhesive layer, and then cut into element pieces by a known method. Next, the adhesive layer is irradiated with radiation to reduce the adhesive strength of the adhesive layer, the sheet is expanded to sufficiently expand the element interval, and element chips are picked up. In the present invention, upon irradiating the pressure-sensitive adhesive layer with radiation, the wafer is bonded to the pressure-sensitive adhesive layer portion, so as to have substantially the same shape as the bonded wafer, the pattern is irradiated with radiation, Radiation is applied to the entire surface of the pressure-sensitive adhesive layer to which the wafer is not attached.

Irradiating radiation in a pattern means irradiating radiation in a pattern such as a stripe, a lattice, a polka dot, a mosaic, or a radial pattern. Forming a certain pattern. And this pattern is
As a whole, it forms substantially the same shape as the attached wafer. When the radiation is applied in this manner, a portion to which the radiation is applied and a portion to which the radiation is not applied are formed in the portion where the wafer is attached. Specifically, 5 to 90% of the total surface area of the pressure-sensitive adhesive layer to which the wafer is attached
It is preferable to perform radiation irradiation to the extent. Radiation is applied to the entire surface of the part where the wafer is not attached.

Since the entire surface of the portion where the wafer is not adhered is irradiated with radiation, the pressure-sensitive adhesive layer located in this portion is sufficiently cured. For this reason, the expansion rate in the expanding step is reduced, and excessive expanding is not required. On the other hand, in the portion where the wafer is attached, the curing of the pressure-sensitive adhesive layer partially proceeds in a pattern, and thus the curing of the pressure-sensitive adhesive layer does not proceed sufficiently. Therefore, the expansion ratio in the expanding step does not decrease much. Therefore, when the pressure-sensitive adhesive sheet for wafer attachment is expanded, the portion to which the wafer is attached is preferentially expanded, so that it can be easily extended without performing excessive expansion, and a sufficient chip interval can be obtained. . However, although the curing does not proceed sufficiently in the portion where the wafer is attached, the adhesive force is reduced to such an extent that the chips can be picked up, so that the chips can be easily picked up after expanding. .

In order to irradiate radiation in such a pattern, it is preferable to use a radiation irradiating apparatus according to the present invention or an adhesive sheet for attaching a wafer as described below.

FIG. 1 schematically shows a radiation irradiation apparatus according to the present invention.
Shown in Irradiation to the pressure-sensitive adhesive sheet 1 is performed from the surface of the substrate 2 on which the pressure-sensitive adhesive layer 3 is not provided. When UV is used as the radiation, the substrate 2 needs to be light-transmitting, but when EB is used as the radiation, the substrate 2
Need not necessarily be light transmissive.

When the radiation is applied, the adhesive layer is irradiated with the radiation in a pattern. Specifically, irradiation is performed through a mask in which a predetermined pattern is formed of a radiation attenuating compound or the like as described below. Examples of the pattern include, but are not limited to, stripes, lattices, polka dots, mosaics, and radial patterns. Among these, particularly preferred patterns include stripes and lattices. It is preferable that each pattern is smaller than the element piece to be manufactured and is periodically arranged.

The irradiation of radiation through the mask is performed on the pressure-sensitive adhesive layer where the wafer is adhered, and the entire surface of the pressure-sensitive adhesive layer where the wafer is not adhered is irradiated. As a result, a portion to which a large amount of radiation is applied (hereinafter referred to as a radiation non-attenuating portion) and a portion to which a small amount of radiation is applied (hereinafter referred to as a radiation attenuating portion)
To form a specific pattern. In the radiation attenuating portion, 1 to 90% of the radiation non-attenuating portion, preferably 5 to 60%
%, Particularly preferably 5 to 30% of the radiation.

As described above, in order to control the amount of radiation applied to the wafer attachment portion and the amount of radiation applied to the non-wafer attached portion, a radiation irradiation apparatus according to the present invention (see FIG. 1). Is used. Irradiation is performed in a closed vessel equipped with a deoxygenator. A radiation-transmissive window 4 is provided on the upper or lower part of the closed container.
Radiation is applied through Irradiation is performed in an inert atmosphere after exhausting oxygen sufficiently. A filter 5 having a radiation attenuating portion 5a having a predetermined pattern between the radiation generating portion 7 and the base material of the pressure-sensitive adhesive sheet for attaching a wafer.
(See FIG. 2). The radiation attenuator 5a
As the whole pattern, the same shape as the bonded wafer is formed. The filter 5 is installed so that the radiation attenuating portion 5a and the adhesive portion to which the wafer is attached face each other. By irradiating radiation through such a filter 5, radiation is irradiated in a pattern.

The radiation attenuator 5a contains a compound having a function of reflecting or absorbing radiation and attenuating the amount of transmitted radiation (hereinafter, radiation attenuating compound). As such a radiation attenuating compound, various compounds can be used without any particular limitation. In the present invention, particularly preferably used radiation attenuating compounds include ultraviolet absorbing compounds such as benzophenone-based compounds, benzotriazole-based compounds, salcylate-based compounds and cyanoacrylate-based compounds; azo pigments, phthalocyanine-based pigments and anthraquinones and perylene. Organic pigments such as a representative condensed polycyclic pigment; and compounds having an electron beam shielding effect such as lead, lead hydroxide, barium, barium hydroxide, and barium stearate. These are used alone or in combination of two or more.

The thickness of the radiation attenuating portion 5a depends on the radiation attenuating compound contained in the radiation attenuating layer, and cannot be said to be any more, but is generally 0.5 to 20 μm, preferably about 1 to 8 μm. is there.

The radiation transmittance of such a radiation attenuating section 5a is 1 to 90%, preferably 5 to 60%, particularly preferably 5 to 30%. Since the entire surface of the portion where the wafer is not attached is irradiated with radiation, the pressure-sensitive adhesive layer located in this portion is sufficiently cured. For this reason, the expansion rate in the expanding step is reduced, and excessive expanding is not required. On the other hand, in the portion where the wafer is attached, the curing of the pressure-sensitive adhesive layer proceeds only in the radiation non-attenuating portion, and the curing of the pressure-sensitive adhesive layer does not occur in the radiation attenuating portion. Does not progress. Therefore, the expansion ratio in the expanding step does not decrease so much. Therefore, it is possible to easily extend without excessively expanding, and to obtain a sufficient chip interval. However, even though the curing does not proceed sufficiently, the adhesive strength is low enough to pick up the chip,
After the expansion, the chip can be easily picked up.

After the expanding step, as shown in FIG. 3, the chips A ₁ , A ₂ ... A to be picked up by the needle rod 7 from the lower surface of the base material 2 according to a conventional method.
₅ are picked up, and the chips A ₁ ... Are picked up by, for example, a suction collet 8 and mounted on a predetermined base. Thus, the wafer chips A ₁ , A ₂
By picking up the chips, you can easily pick up the chips because there is sufficient chip spacing, and the adhesion is sufficiently reduced, so that good quality chips without contamination can be obtained. Can be

Next, the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention will be described. As shown in FIG. 4, FIG. 5 or FIG. 6, the pressure-sensitive adhesive sheet 1 for attaching a wafer according to the present invention was formed in a pattern with the substrate 2, the radiation-curable pressure-sensitive adhesive layer 3, and the like. And a radiation attenuating section 9. The radiation attenuating section 9 includes the base material 2 and the radiation-curable pressure-sensitive adhesive layer 3.
(FIG. 4), on the surface of the substrate 2 opposite to the radiation-curable pressure-sensitive adhesive layer 3 (FIG. 5), or on both surfaces of the substrate 2 (Not shown). Before use, in order to protect the radiation-curable pressure-sensitive adhesive layer 3, it is preferable to temporarily adhere the release sheet 10 to the upper surface of the radiation-curable pressure-sensitive adhesive layer 3 as shown in FIG.

The shape of the pressure-sensitive adhesive sheet 1 according to the present invention can take any shape such as a tape shape and a label shape. Hereinafter, the substrate 2, the radiation-curable pressure-sensitive adhesive layer 3, and the radiation-attenuating portion 9 used in the present invention will be sequentially described.

As the substrate 2, a substrate having radiation transparency is used. Various types of such base materials have been conventionally known. For example, when using ultraviolet rays as radiation, polyester, polyethylene,
Polypropylene, polybutene, polybutadiene, vinyl chloride, vinyl chloride copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth)
Examples of the base material include resin base materials such as an acrylate copolymer, polystyrene, and polycarbonate, and base materials obtained by applying a silicone resin or the like to the surface of these resin base materials and subjecting them to release treatment. When an electron beam is used as the radiation, a fluororesin or a colored opaque film is used. Further, for the purpose of the present invention,
It is preferable to use a substrate having a Young's modulus of about 0 ² to 10 ⁴ Kg / cm ² .

As the substrate 2, one of the above-mentioned resin films may be used alone, or a laminated film obtained by laminating two or more films may be used. The thickness of the substrate as described above is usually from 10 to 300 μm, preferably from 50 to 150 μm.

In the pressure-sensitive adhesive sheet of the present invention, as will be described later, the electron beam (EB) or ultraviolet (U)
The substrate 2 is not required to be transparent in the case of EB irradiation, but needs to be transparent in the case of UV irradiation.

As the radiation-curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 3, conventionally known radiation-curable pressure-sensitive adhesives can be widely used, and an acrylic pressure-sensitive adhesive is preferable as a main component thereof.
An acrylic polymer selected from a homopolymer and a copolymer having an acrylic acid ester as a main constituent monomer unit, a copolymer with another functional monomer, and a mixture of these polymers are used. For example, acrylates include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, and the like. Can be preferably used.

Further, in order to enhance the compatibility with the oligomer described later, a monomer such as acrylic acid or methacrylic acid, acrylonitrile, vinyl acetate or the like may be copolymerized. The molecular weight of the acrylic polymer obtained by polymerizing these monomers is 2.0 × 10 ^{5 to} 10.0 × 10 ⁵ , preferably 4.0 × 10 ^{5 to} 8.0 × 10 ⁵ . is there.

By incorporating a radiation-polymerizable compound into the radiation-curable pressure-sensitive adhesive layer as described above, the wafer is cut and separated, and then the pressure-sensitive adhesive layer is irradiated with radiation to reduce the adhesive strength. Can be. Examples of such a radiation polymerizable compound include, for example, JP-A-60-19
No. 6,956, and JP-A-60-223,139, a low-molecular compound having at least two or more photopolymerizable carbon-carbon double bonds in a molecule capable of forming a three-dimensional network by irradiation with light. Molecular weight compounds are widely used, specifically, trimethylolpropane triacrylate,
Tetramethylol methane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate or 1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol Diacrylate, commercially available oligoester acrylate and the like are used.

As the radiation polymerizable compound, a urethane acrylate oligomer can be used in addition to the acrylate compound described above. The urethane acrylate oligomer includes a polyol compound such as a polyester type or a polyether type, and a polyvalent isocyanate compound such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4 -Acrylate or methacrylate having a hydroxyl group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, on a terminal isocyanate urethane prepolymer obtained by reacting xylylene diisocyanate, diphenylmethane 4,4-diisocyanate or the like. , 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate Obtained by. This urethane acrylate oligomer is a radiation polymerizable compound having at least one carbon-carbon double bond.

The urethane acrylate oligomer has a molecular weight of 3,000 to 30,000, preferably 3,000 to 10,000, more preferably 400 to 10,000.
It is preferable to use a value of 0 to 8000 because even when the surface of the semiconductor wafer is rough, the adhesive does not adhere to the chip surface when the wafer chip is picked up. When a urethane acrylate oligomer is used as the radiation polymerizable compound, Japanese Patent Application Laid-Open No.
As compared with the case of using a low-molecular-weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule as disclosed in JP-A No. 6-2006, an extremely excellent pressure-sensitive adhesive sheet is obtained. That is, the adhesive force of the pressure-sensitive adhesive sheet before the irradiation is sufficiently large, and the adhesive force is sufficiently reduced after the radiation irradiation, so that the pressure-sensitive adhesive does not remain on the chip surface when the wafer chip is picked up.

The mixing ratio of the acrylic pressure-sensitive adhesive and the urethane acrylate oligomer in the radiation-curable pressure-sensitive adhesive of the present invention is in the range of 50 to 900 parts by weight of the urethane acrylate oligomer per 100 parts by weight of the acrylic pressure-sensitive adhesive. It is preferably used in an amount. In this case,
The resulting pressure-sensitive adhesive sheet has a large initial adhesive force, and its adhesive force is significantly reduced after irradiation, so that wafer chips can be easily picked up from the pressure-sensitive adhesive sheet.

In the present invention, abrasive grains may be dispersed in the substrate. This abrasive has a particle size of 0.5 to 100 μm.
m, preferably 1 to 50 μm, and a Mohs hardness of 6
-10, preferably 7-10. Specifically, green carborundum, artificial corundum, optical emery, white alundum, boron carbide, chromium oxide
(III), cerium oxide, diamond powder and the like are used. Such abrasive grains are preferably colorless or white. Such abrasive grains are contained in the base material 2 in an amount of 0.5 to
It is present in an amount of 70% by weight, preferably 5 to 50% by weight. Such abrasive grains are particularly preferably used when the cutting blade is used at such a depth as to cut not only into the wafer but also into the substrate 2.

By including the above-mentioned abrasive grains in the base material, the cutting blade cuts into the base material, and even if the adhesive adheres to the cutting blade, the clogging is easily performed by the polishing effect of the abrasive grains. Can be removed.

By mixing an isocyanate-based curing agent in the above-mentioned pressure-sensitive adhesive, the initial adhesive strength can be set to an arbitrary value. As such a curing agent,
Specifically, a polyvalent isocyanate compound such as 2,4
-Tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate,
1,4-xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-
2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, lysine isocyanate and the like are used.

Furthermore, in the case of UV irradiation in the above-mentioned pressure-sensitive adhesive, by mixing a UV initiator, the polymerization curing time by UV irradiation and the amount of UV irradiation can be reduced.

Specific examples of such a UV initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
Benzyldiphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone and the like can be mentioned.

The radiation attenuating portion 9 is formed between the base material 2 and the radiation-curable pressure-sensitive adhesive layer 3 or formed on the surface of the substrate 2 opposite to the radiation-curable pressure-sensitive adhesive layer 3. Or formed on both sides of the substrate 2. The radiation attenuator 9 preferably has substantially the same shape as the wafer to be attached. The radiation attenuator 9 is formed in a pattern. Examples of the pattern include, but are not limited to, stripes, lattices, polka dots, mosaics, and radial patterns. Among these, particularly preferred patterns include stripes and lattices. It is preferable that each pattern is smaller than the element piece to be manufactured and is periodically arranged. Particularly preferred embodiments of the radiation attenuator 9 are shown in FIGS.

The radiation attenuating section 9 is a layer containing the above-described radiation attenuating compound. Such a radiation attenuating compound is used by dissolving or dispersing in a suitable binder agent, and is applied or printed in a predetermined pattern to form the radiation attenuating portion 9.

The thickness of the radiation attenuating portion 9 depends on the radiation attenuating compound contained in the radiation attenuating portion, and although it cannot be said, it is generally 0.5 to 20 μm, preferably 1.0 to 8 μm. It is about.

The radiation transmittance of the radiation attenuator 9 is 1 to 90%, preferably 5 to 60%.
Particularly preferably, it is 5 to 30%. The radiation attenuator 9 has a Young's modulus of 1 × 10 ^{2 to} 5 × 10 ⁴ Kg / cm ² , preferably 5 × 10 ² to 1 × 10 ⁴ Kg / cm ² , particularly preferably 1 × 10 ^{3 to} 5 kg. It is about × 10 ³ Kg / cm ² and does not affect the elongation of the base material and the pressure-sensitive adhesive layer in the expanding step.

The pressure-sensitive adhesive sheet for attaching a wafer according to the present invention comprises:
It comprises the above-described base material 2, pressure-sensitive adhesive layer 3 and radiation attenuating section 9. When radiation is irradiated from the substrate side of the pressure-sensitive adhesive sheet for attaching a wafer having such a configuration, the amount of radiation applied to a portion of the pressure-sensitive adhesive layer 3 that is covered with the radiation attenuating portion 9 is attenuated, and the radiation amount other than the portion is reduced. A large amount of radiation is irradiated to other portions (hereinafter, sometimes referred to as radiation non-attenuation portions). As a result, the pressure-sensitive adhesive layer in the radiation non-attenuating portion is sufficiently cured, and the expansion rate in the expanding step is reduced. Further, since the curing of the pressure-sensitive adhesive layer covered with the radiation attenuating portion 4 does not proceed sufficiently, the expansion ratio in the expanding step does not decrease so much. Therefore, it is possible to easily extend without excessively expanding, and to obtain a sufficient chip interval. Further, in the radiation non-attenuating portion, the curing of the pressure-sensitive adhesive layer sufficiently proceeds, and the adhesive force is remarkably reduced, so that the chip can be easily picked up.

Hereinafter, a method for using the pressure-sensitive adhesive sheet according to the present invention will be described. When the peelable sheet 10 is provided on the upper surface of the pressure-sensitive adhesive sheet 1 according to the present invention, the sheet 1
0 is removed, and then the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 is placed with the pressure-sensitive adhesive layer 3 facing upward, and as shown in FIG.
A semiconductor wafer A to be diced on the upper surface of the pressure-sensitive adhesive layer 3 so as to overlap the radiation attenuating section 9.
The wafer A is diced in this bonded state (FIG. 10), followed by washing and drying. At this time, the wafer chips are sufficiently adhered and held on the pressure-sensitive adhesive sheet by the pressure-sensitive adhesive layer 3, so that the wafer chips do not fall off during the respective steps.

Next, each wafer chip is picked up from the adhesive sheet and mounted on a predetermined base, and prior to picking up, as shown in FIG.
V) or radiation B such as an electron beam (EB) is applied to the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 to polymerize and cure the radiation-polymerizable compound contained in the pressure-sensitive adhesive layer 3, and then expand. When the radiation-sensitive polymerizable compound is polymerized and cured by irradiating the pressure-sensitive adhesive layer 3 in this manner, the curing of the pressure-sensitive adhesive layer in the portion covered with the radiation attenuating portion 9 does not progress. The expansion rate of the seat does not decrease much. On the other hand, since a large amount of radiation is applied to the radiation non-attenuated portion, curing proceeds sufficiently and the expansion rate is significantly reduced. As a result, in the expanding step, the portion covered by the radiation attenuating section 9 is easily expanded, so that a desired chip interval can be easily obtained without performing excessive expanding. After the expanding step, the chip A is picked up according to a conventional method.

[0051]

As described above, according to the wafer dicing method, the radiation irradiation apparatus, and the adhesive sheet for attaching a wafer according to the present invention, it is easy to obtain a desired chip interval in the expanding step. Eliminates excessive expanding.

[0052]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0053]

[Radiation irradiation device]

[0054]

Example 1 An acrylic polymer (copolymer of n-butyl acrylate and acrylic acid) was used as a substrate, using a soft vinyl chloride film (containing 30% of a plasticizer, thickness 80 μm) as an adhesive on the substrate. 100 parts by weight and a molecular weight of 80
100 parts by weight of a urethane acrylate-based oligomer of No. 00 and 10 parts by weight of a curing agent (aromatic diisocyanate-based) were cast on a release material composed of a polyethylene terephthalate film (38 μm) obtained by subjecting the composition to silicone treatment. A laminated adhesive tape was prepared.

As a filter, a filter was prepared by printing an acrylic polymer containing 3 parts by weight of 2,4-dihydroxybenzophenone on a glass by screen printing in a shape of 2 mm square at 1 mm intervals both vertically and horizontally.

After the 5-inch wafer was attached to the adhesive tape, the wafer was mounted on a flat frame, and then cut into 5 mm square chips with a 50 μm-thick diamond blade. After this, the illuminance 2
An ultraviolet ray of 00 mW / cm ² was irradiated for 2 seconds.

Next, the dicing tape was expanded by 15% using an expanding jig. The expansion rate of the portion where the wafer was attached was 8 to 10%.

[0058]

Example 2 Example 2 was repeated except that an ethylene-methacrylic acid copolymer was used as a substrate.

The expansion rate of the portion where the wafer is attached is 5 to 7
%Met.

[0060]

Comparative Example 1 The same procedure as in Example 1 was carried out except that ultraviolet light was irradiated through glass without using a filter.

The expansion rate of the portion where the wafer is stuck is 3 to 5
%Met.

[0062]

Comparative Example 2 The same operation as in Example 1 was performed except that ultraviolet light was irradiated through glass without using a filter.

The expansion ratio of the portion where the wafer was attached was 1%.

[0064]

[Adhesive sheet for attaching wafer]

[0065]

Example 3 A soft vinyl chloride film (containing 30% of a plasticizer, a thickness of 80 μm) was used as a base material.
Acrylic resin containing 3 parts by weight of 4-dihydroxybenzophenone is screen-printed to a width of 1 mm and an interval of 2 mm
Printed in stripes. As an adhesive, 100 parts by weight of an acrylic polymer (copolymer of n-butyl acrylate and acrylic acid), 100 parts by weight of a urethane acrylate oligomer having a molecular weight of 8000, and 10 parts by weight of a curing agent (aromatic diisocyanate) Was cast on a release material composed of a silicone-treated polyethylene terephthalate film (38 μm) to prepare an adhesive tape bonded to the above substrate.

After sticking a 5-inch wafer to the printing section on this adhesive tape, it was mounted on a flat frame and
Using a thick diamond blade, full-cut into 5 mm square chips. Thereafter, ultraviolet light having an illuminance of 200 mW / cm ² was irradiated from the surface on the substrate side for 2 seconds.

Next, the dicing tape was expanded by 15% using an expanding jig. Table 1 shows the expansion ratio of the portion where the wafer was attached.

[0068]

Example 4 The same operation as in Example 1 was carried out except that a monoazo dye was used in place of 2,4-dihydroxybenzophenone. Table 1 shows the expansion ratio of the portion where the wafer was attached.

[0069]

Comparative Example 3 The same operation as in Example 1 was performed except that the printing layer (radiation attenuating portion) was not provided. Table 1 shows the expansion ratio of the portion where the wafer was attached.

[0070]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view of a radiation irradiation apparatus according to the present invention.

FIG. 2 is a drawing showing a filter used in the radiation irradiation apparatus of the present invention.

FIG. 3 is an explanatory diagram of a pickup step.

FIG. 4 is a sectional view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 5 is a cross-sectional view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 6 is a cross-sectional view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 7 is a perspective view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 8 is a perspective view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 9 shows a state in which a wafer is attached to the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 10 shows a state where the attached wafer is diced.

FIG. 11 shows a state in which irradiation is performed after dicing to expand.

FIG. 12 is an explanatory diagram of a pickup step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet for wafer attachment 2 ... Base material 3 ... Adhesive layer 4 ... Window of closed container 5 ... Filter 5a ... Radiation attenuating part 6 ... Radiation generating part 7 ... Push-up needle rod 8 ... Suction collet 9 ... Radiation attenuating part 10 … Peelable sheet A… wafer B… radiation

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-249343 (JP, A) JP-A-5-179211 (JP, A) JP-A-5-36828 (JP, A) JP-A-63-1988 137449 (JP, A) JP-A-2-60147 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/301

Claims (3)

(57) [Claims] 1. A wafer attached on an adhesive layer of an adhesive sheet for attaching a wafer, comprising a base material and an adhesive layer whose adhesive strength decreases when irradiated with radiation, is cut into element pieces. Separating, irradiating the pressure-sensitive adhesive layer with radiation to reduce the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer, expanding the sheet to expand the element interval, and picking up element pieces, the wafer dicing method, In irradiating the radiation, the adhesive layer portion on which the wafer is adhered is irradiated with radiation in a pattern so as to have substantially the same shape as the adhered wafer, and the adhesive layer on which the wafer is not adhered. A wafer dicing method comprising irradiating the entire surface with radiation. 2. A wafer adhered on an adhesive layer of an adhesive sheet for attaching a wafer, comprising a base material and an adhesive layer whose adhesive strength decreases when irradiated with radiation, is cut into element pieces. Separation, radiation irradiation to the pressure-sensitive adhesive layer to reduce the adhesive force of the pressure-sensitive adhesive layer, expand the sheet to expand the element spacing, in a radiation irradiation apparatus used for wafer dicing to pick up element small pieces, A filter provided with a radiation attenuating portion having a pattern of substantially the same shape as the attached wafer is provided between the radiation generating portion of the apparatus and the base material of the adhesive sheet for attaching the wafer. Radiation irradiation equipment. 3. A pressure-sensitive adhesive sheet for attaching a wafer, comprising a substrate and a radiation-curable pressure-sensitive adhesive layer provided thereon, wherein a radiation-attenuating portion in a pattern is provided on at least one surface of the substrate. A pressure-sensitive adhesive sheet for attaching a wafer, wherein the pressure-sensitive adhesive sheet is bonded.