JP2728333B2 - Adhesive sheet for attaching wafer and chip pick-up method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive sheet for attaching a wafer and a method for picking up a chip, and more particularly, to a method for attaching a wafer which can omit an expanding step of an adhesive sheet which is usually performed when picking up a chip. The present invention relates to a method for picking up an adhesive sheet and a chip.

[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. The expanding step is performed to stretch the adhesive tape to which the diced chips are attached, to increase the chip interval, and to facilitate chip pickup.

Conventionally, wafers having a size of 6 inches or less have been widely used as such semiconductor wafers. However, in recent years, with the development of the semiconductor industry, in order to produce chips more efficiently, a wafer having a larger diameter has been used. For example, use of an 8-inch wafer is being considered. However, when using an 8-inch wafer,
As a matter of course, the dicing device and the bonding (pickup) device increase in size. Particularly, in order to increase the number of chips to be produced, a larger expanding device is required to obtain a sufficient chip interval.

[0004] For this reason, there has been a demand for an adhesive tape for attaching a wafer, which can accurately pick up chips without causing any chip-to-chip contact without expanding and without expanding. Was.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems associated with the prior art described above, and to omit the step of expanding the adhesive sheet which is usually performed when picking up chips. It is an object of the present invention to provide an adhesive sheet for attaching a wafer and a method for picking up chips.

[0006]

The pressure-sensitive adhesive sheet for bonding a wafer according to the present invention has a Young's modulus of 10 ^-1 to 10 ¹ MPa and a dimensional recovery rate in a pressure-sensitive adhesive sheet for bonding a wafer comprising a base film and a pressure-sensitive adhesive layer. 90 % or more natural rubber, isoprene
The base film is characterized by comprising a rubber-like elastic body made of rubber or a vulcanized product thereof.

The method of picking up a chip according to the present invention uses a natural rubber, an isoprene rubber or a natural rubber having a Young's modulus of 10 ^-1 to 10 ¹ MPa and a dimensional recovery of 90 % or more.
A wafer is stuck on an adhesive sheet for sticking a wafer, which is composed of a base film made of a rubber-like elastic body made of these vulcanizates and an adhesive layer, and the wafer is diced, and element chips ( After the dicing, the adhesive sheet is transferred to a pickup device without expanding, the chip is pushed up from the back surface of the adhesive sheet by a push-up pin, and the chip is picked up by a suction collet.

[0008]

DETAILED DESCRIPTION OF THE INVENTION As the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention, for example, a pressure-sensitive adhesive sheet 10 in which a pressure-sensitive adhesive layer 2 is formed on a base film 1 as shown in FIG. 1 can be exemplified. . Before using the pressure-sensitive adhesive sheet 10, in order to protect the pressure-sensitive adhesive layer 2, it is preferable to temporarily adhere the releasable sheet 3 to the upper surface of the pressure-sensitive adhesive layer 2 as shown in FIG. 2.

The shape of the pressure-sensitive adhesive sheet 10 according to the present invention can take any shape such as a tape shape and a label shape. As the base film 1, a base film made of a rubber-like elastic material having a Young's modulus of 10 ^-1 to 10 ¹ MPa is used. The dimensional recovery of the rubber-like elastic body is 90 % or more.
The dimensional recovery rate indicates a value measured as follows.

That is, the rubber-like elastic body is 15 mm × 10
0% sheet, 25% while applying load in the longitudinal direction
(25 mm) Elongated, held in this state for 10 minutes, and then the length (Xmm) at which the sheet shrank after removing the load
And the length (25 mm) of the stretched sheet (percentage)
Is the dimensional recovery rate.

[0011]

(Equation 1)

As the rubber-like elastic body having the above-mentioned Young's modulus and dimensional recovery rate, specifically, natural rubber, isoprene rubber or a vulcanized product thereof is used. The film thickness of the base film 1 formed from such a rubber-like elastic material is usually about 30 to 150 μm, preferably 3 to 150 μm.
It is about 0 to 80 μm.

The base film 1 formed from such a rubber-like elastic material is rich in elasticity. By applying an appropriate load to only a part of the base film, it is possible to selectively expand only that part. Can be. For this reason, it is not necessary to expand the entire base film as conventionally performed. That is, the chip can be picked up without expanding. In addition, "without expanding" means that the expansion rate of the film based on the entire length of the base film is 3% or less.

As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 formed on the base film 1, conventionally known pressure-sensitive adhesives can be widely used, but acrylic pressure-sensitive adhesives are preferable. Conventionally known acrylic pressure-sensitive adhesives are widely used,
Specifically, an acrylic polymer selected from a homopolymer and a copolymer having an acrylic acid ester as a main structural unit, a copolymer with another functional monomer, and a mixture of these polymers are used. . For example, carbon number 1-10
Acrylic ester of alkyl alcohol, having 1 carbon atom
Methacrylic acid esters of alkyl alcohols of from 10 to 10,
Vinyl acetate, acrylonitrile, vinyl alkyl ether and the like can be preferably used. The acrylic copolymers can be used alone or in combination of two or more.

As the functional monomer, acrylic acid, methacrylic acid, maleic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and the like are used. The adhesive force and cohesive force of the copolymer pressure-sensitive adhesive having a functional monomer can be set to arbitrary values by using a crosslinking agent. Examples of such a crosslinking agent include a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, a chelate compound and the like.
Specific examples of the polyvalent isocyanate compound include toluylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and adducts thereof. Specific examples of the polyvalent epoxy compound include ethylene glycol diglycidyl ether and terephthalic acid diglycidyl ester acrylate. As the polyvalent aziridine compound, specifically, tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, hexa [ 1- (2-methyl)
-Aziridinyl] triphosphatriazine and the like. Specific examples of the chelate compound include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), and the like.

The catalyst obtained by polymerizing these monomers is
The molecular weight of the ril copolymer is 1.0 × 10^Five~ 10.0
× 10^FiveAnd preferably 4.0 × 10^Five~ 8.0 ×
10 ^FiveIt is. In addition, radiation is applied as an adhesive layer
Cures to reduce adhesion during pickup
What can be used can also be used. Specifically,
Radiation polymerizable with acrylic copolymer as main ingredient
It is preferable to use a pressure-sensitive adhesive containing a compound. this
Such radiation-polymerizable compounds include, for example, those described in
0-196,956 and JP-A-60-223,
139 by light irradiation as disclosed in
Photopolymerizable carbon-carbon double bond in a molecule that can be dimensionally reticulated
Low molecular weight compounds having at least two or more are widely used
Specifically, trimethylolpropane triacrylate
Rate, tetramethylolmethanetetraacrylate,
Pentaerythritol triacrylate, pentaerythr
Litol tetraacrylate, dipentaerythritol
Monohydroxypentaacrylate, dipentaerythri
Tall hexaacrylate or 1,4-butylene
Recall diacrylate, 1,6-hexanediol di
Acrylate, polyethylene glycol diacrylate
And commercially available oligoester acrylates are used.
You.

Further, 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.

Such a urethane acrylate oligomer has a molecular weight of, particularly, 3000 to 30,000, preferably 3000 to 10,000, and 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 to the urethane acrylate oligomer in the pressure-sensitive adhesive is such that the urethane acrylate-based oligomer is used in an amount of 50 to 900 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive. preferable. In this case, the resulting pressure-sensitive adhesive sheet has a large initial adhesive strength, and the adhesive strength is significantly reduced after irradiation, so that wafer chips can be easily picked up from the pressure-sensitive adhesive sheet.

If necessary, the pressure-sensitive adhesive layer 2 may contain, in addition to the above-mentioned pressure-sensitive adhesive and a radiation-polymerizable compound, a compound which is colored by irradiation with radiation. By including a compound to be colored in the pressure-sensitive adhesive layer 2 by such radiation irradiation, the sheet is colored after the pressure-sensitive adhesive sheet is irradiated with the radiation, and therefore, the detection accuracy when detecting the wafer chips by the optical sensor. And malfunction does not occur when picking up a wafer chip. In addition, an effect is obtained that it is immediately possible to visually determine whether or not radiation has been applied to the adhesive sheet.

The compound that is colored by irradiation with radiation is a compound that is colorless or pale before irradiation with radiation, but is a compound that becomes colored by irradiation with radiation. A preferred specific example of this compound is a leuco dye. As the leuco dye, commonly used triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based and spiropyran-based dyes are preferably used. Specifically, 3- [N-
(P-tolylamino)]-7-anilinofluoran, 3
-[N- (p-tolyl) -N-methylamino] -7-anilinofluoran, 3- [N- (p-tolyl) -N-ethylamino] -7-anilinofluoran, 3-diethylamino -6-methyl-7-anilinofluoran, crystal violet lactone, 4,4 ', 4 "-trisdimethylaminotriphenylmethanol, 4,4', 4"
-Trisdimethylaminotriphenylmethane and the like.

Examples of the developer preferably used together with these leuco dyes include conventionally used electron acceptors such as a phenol formalin resin initial polymer, an aromatic carboxylic acid derivative, and activated clay. In the case where is changed, various known color formers can be used in combination. Such a compound which is colored by irradiation with radiation may be once dissolved in an organic solvent or the like and then included in the adhesive layer, or may be finely powdered and included in the pressure-sensitive adhesive layer. This compound is present in the pressure-sensitive adhesive layer in an amount of 0.0
It is desirable to use it in an amount of 1 to 10% by weight, preferably 0.5 to 5% by weight. When the compound is used in an amount exceeding 10% by weight, the radiation applied to the pressure-sensitive adhesive sheet is excessively absorbed by the compound, and thus the curing of the pressure-sensitive adhesive layer may be insufficient. When used in an amount of less than 0.01% by weight, the pressure-sensitive adhesive sheet may not be sufficiently colored when irradiated with radiation, and malfunction may easily occur when picking up a wafer chip.

In some cases, the light-scattering inorganic compound powder may be contained in the pressure-sensitive adhesive layer 2 in addition to the pressure-sensitive adhesive and the radiation-polymerizable compound as described above. By including such a light-scattering inorganic compound powder in the pressure-sensitive adhesive layer 2, even if the surface of an adherend such as a semiconductor wafer becomes gray or black for some reason, the pressure-sensitive adhesive sheet is irradiated with radiation such as ultraviolet rays. Then, even in the grayed or blackened part, the adhesive strength is sufficiently reduced,
Therefore, there is obtained an effect that the adhesive does not adhere to the surface of the wafer chip when the wafer chip is picked up, and that the adhesive has sufficient adhesive strength before the irradiation of the radiation.

The light-scattering inorganic compound is formed of an ultraviolet (U)
V) or a compound capable of irregularly reflecting radiation when irradiated with radiation such as electron beam (EB), specifically, silica powder, alumina powder, silica-alumina powder, mica powder And the like. The light-scattering inorganic compound preferably reflects the above-described radiation almost completely, but of course, a compound that absorbs the radiation to some extent can also be used.

The light-scattering inorganic compound is preferably in the form of a powder and has a particle size of 1 to 100 μm, preferably 1 to 2 μm.
Desirably, it is about 0 μm. This light-scattering inorganic compound is contained in the pressure-sensitive adhesive layer in an amount of 0.1 to 10% by weight, preferably 1 to 10% by weight.
Preferably, it is used in an amount of ４4% by weight. When the compound is used in an amount of more than 10% by weight in the pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer may decrease, while
If the content is less than 10 wt%, when the surface of the semiconductor wafer is grayed or blackened, even if the portion is irradiated with radiation, the adhesive strength may not be sufficiently reduced and the adhesive may remain on the wafer surface during pickup.

The pressure-sensitive adhesive sheet obtained by adding the light-scattering inorganic compound powder to the pressure-sensitive adhesive layer can be used even if the semiconductor wafer surface is grayed or blackened for some reason. It is considered that the reason why the irradiation of the blackened portion with the radiation is such that the adhesive force is sufficiently reduced even in this portion is as follows. That is, the pressure-sensitive adhesive sheet 10 used in the present invention has the pressure-sensitive adhesive layer 2, and when the pressure-sensitive adhesive layer 2 is irradiated with radiation, the radiation-polymerizable compound contained in the pressure-sensitive adhesive layer 2 is cured to cure the radiation-polymerizable compound. The adhesive strength will be reduced. However, a grayed or blackened portion may occur on the semiconductor wafer surface for some reason. In such a case, when the pressure-sensitive adhesive layer 2 is irradiated with radiation, the radiation passes through the pressure-sensitive adhesive layer 2 and reaches the wafer surface. However, if there is a grayed or blackened portion on the wafer surface, the radiation is emitted at this portion. It is absorbed and no longer reflected. For this reason, the radiation which should be used for curing the pressure-sensitive adhesive layer 2 is absorbed in the grayed or blackened portions, and the curing of the pressure-sensitive adhesive layer 2 becomes insufficient, and the adhesive strength is not sufficiently reduced. become. Therefore, it is considered that the adhesive will adhere to the chip surface when the wafer chip is picked up.

However, when the light-scattering inorganic compound powder is added to the pressure-sensitive adhesive layer 2, the irradiated radiation collides with the compound before reaching the wafer surface and changes its direction. Therefore, even if there is a grayed or blackened part on the wafer chip surface, the diffusely reflected radiation penetrates well into the area above this part, and therefore, the grayed or blackened part is also hardened sufficiently. I do. For this reason,
By adding the light-scattering inorganic compound powder into the pressure-sensitive adhesive layer, even if there is a grayed or blackened portion on the semiconductor wafer surface for some reason, the pressure-sensitive adhesive layer is insufficiently cured at this portion. Therefore, the adhesive does not adhere to the chip surface when picking up the wafer chip.

Further, in the present invention, abrasive grains may be dispersed in the substrate film. This abrasive has a particle size of 0.5 to
The thickness is 100 μm, preferably 1 to 50 μm, and the Mohs hardness is 6 to 10, preferably 7 to 10. In particular,
Green carborundum, artificial corundum, optical emery, white alundum, boron carbide, chromium (III) oxide, 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 film 2 in an amount of 0.5 to 70% by weight, preferably 5 to 50% by weight.
Are present in amounts. 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 base film 2.

By including the abrasive grains in the base film as described above, the cutting blade cuts into the base film, and even if an adhesive is adhered to the cutting blade, the abrasive effect of the abrasive grains causes the cutting effect. Jams can be easily removed. The pressure-sensitive adhesive as described above can set the adhesive force and the cohesive force to arbitrary values by using a crosslinking agent. Examples of such a crosslinking agent include a polyvalent isocyanate compound, a polyvalent epoxy compound, a polyvalent aziridine compound, a chelate compound and the like. Specific examples of the polyvalent isocyanate compound include toluylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and adducts thereof. Specific examples of the polyvalent epoxy compound include ethylene glycol diglycidyl ether and terephthalic acid diglycidyl ester acrylate. As the polyvalent aziridine compound, specifically, tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) -aziridinyl] phosphine oxide, hexa [ 1- (2-methyl) -aziridinyl] triphosphatriazine and the like are used. Specific examples of the chelate compound include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), and the like.

Further, 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 procedure of the chip pickup method according to the present invention will be described below. When the peelable sheet 3 is provided on the upper surface of the pressure-sensitive adhesive sheet 10, the sheet 3 is removed, and then the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 10 is placed with the pressure-sensitive adhesive layer 2 facing upward, as shown in FIG. Then, a semiconductor wafer A to be diced is attached to the upper surface of the pressure-sensitive adhesive layer 2. Various processes of dicing, cleaning, and drying are added to the wafer A in this state of attachment. At this time, the wafer chip is sufficiently bonded and held to the pressure-sensitive adhesive sheet by the pressure-sensitive adhesive layer 2, so that the wafer chip does not fall off during each of the above steps.

Next, each wafer chip is picked up from the adhesive sheet and mounted on a predetermined base.
At this time, prior to or at the time of pickup, as shown in FIG. 4, ionizing radiation B such as ultraviolet rays (UV) or electron beams (EB) is irradiated onto the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive sheet 10, and the pressure-sensitive adhesive layer The radiation polymerizable compound contained in 2 is polymerized and cured. When the pressure-sensitive adhesive layer 2 is irradiated with radiation to polymerize and cure the radiation-polymerizable compound, the adhesive strength of the pressure-sensitive adhesive is greatly reduced, and only a slight adhesive strength remains.

Irradiation of the radiation to the pressure-sensitive adhesive sheet 10 is preferably performed from the surface of the base film 1 where the pressure-sensitive adhesive layer 2 is not provided. Therefore, as described above, when using UV as radiation, the base film 1 needs to be light-transmitting, but when using EB as radiation, the base film 1 is not necessarily light-transmitting. No need.

After the adhesive layer 2 at the portion where the wafer chips A ₁ , A ₂ ... Are provided is irradiated with radiation to reduce the adhesive strength of the adhesive layer 2, the adhesive sheet 10 is removed. Transfer to pickup station. Conventionally, the pressure-sensitive adhesive sheet 10 was expanded here, and the chips were picked up after sufficiently widening the chip interval. However, if the wafer-adhering pressure-sensitive adhesive sheet according to the present invention is used, the expanding step can be omitted. Can be. That is, without expanding the sheet, the chips A ₁ to be picked up by the push-up pins 4 are pushed up from the lower surface of the base film 1 as shown in FIG. Since the base film 1 has a sufficient Young's modulus and dimensional recovery rate, only chips to be picked up are pushed up, and other chips do not shift or peel off from the sheet. When the push-up pins 4 are removed, the sheet immediately returns to the flat state, and the next pickup can be performed without any trouble without wrinkles or distortion remaining on the sheet. The chips pushed up from the adhesive sheet 10 are picked up by, for example, the suction collet 5, and are mounted on a predetermined base. When the wafer chips A ₁ , A _2, ... Are picked up by using the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention as described above, the chips can be picked up smoothly without expanding the pressure-sensitive adhesive sheet. it can.

It is not always necessary to irradiate the entire surface of the bonding surface of the wafer A at one time, and the radiation may be partially irradiated several times.
Each of the wafer chips A ₁ , A _2, ... To be picked up is irradiated by a radiation irradiation tube that irradiates only the corresponding back surface to reduce the adhesive force of only the adhesive at that portion and then pushed up. 4, the wafer chips A ₁ , A ₂ ......
Can be picked up sequentially.
FIG. 6 shows a modification of the above-described radiation irradiation method. In this case, the inside of the push-up pin 4 is made hollow, and a radiation source 6 is provided in the hollow portion so that radiation irradiation and pickup can be performed simultaneously. In this way, the apparatus can be simplified, and at the same time, the time required for the pick-up operation can be shortened.

[0036]

As described above, according to the present invention, the conventional expanding step can be omitted, so that a chip can be picked up by a compact apparatus even when a large-diameter wafer is used. it can.

[0037]

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

[0038]

EXAMPLE An acrylic pressure-sensitive adhesive (copolymer of n-butyl acrylate and acrylic acid) was applied to a base film (40 μm thick) made of vulcanized natural rubber to a thickness of 10 μm, An adhesive sheet was produced. After bonding an 8-inch silicon wafer on the pressure-sensitive adhesive layer of the obtained pressure-sensitive adhesive sheet and dicing the wafer, chips were picked up by a non-expandable die bonder. The dicing and pickup conditions at this time are as follows.

Dicing depth: 2 from tape surface
0 μm Push-up pins: 4 Diameter of suction holder: 28 mm φ Collet: pyramid collet Push-up distance: 2 mm Dicing size: 8 mm × 8 mm As a result, chip breakage due to contact between chips and failure due to malfunction of the die bonder device due to slack of tape occur. Good pick-up operation.

[0040]

COMPARATIVE EXAMPLE The procedure was the same as in the example, except that the substrate film was a vinyl chloride film (thickness: 40 μm). As a result, the position of the chip was shifted during the pickup operation because the slack of the tape was not recovered, and the die bonder malfunctioned.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 2 is a schematic sectional view of the pressure-sensitive adhesive sheet for attaching a wafer according to the present invention.

FIG. 3 is an explanatory diagram of a chip pickup method according to the present invention.

FIG. 4 is an explanatory diagram of a chip pickup method according to the present invention.

FIG. 5 is an explanatory diagram of a chip pickup method according to the present invention.

FIG. 6 is an explanatory diagram of a chip pickup method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Adhesive layer 3 ... Peelable sheet 4 ... Push-up pin 5 ... Suction collet 6 ... Radiation source A ... Wafer B ... Radiation

Claims (2)

(57) [Claims] An adhesive sheet for attaching a wafer, comprising a base film and an adhesive layer, having a Young's modulus of 10 ^-1 to 10 ¹ MPa and a dimensional recovery rate of
90 % or more of natural rubber, isoprene rubber or these
A pressure- sensitive adhesive sheet for attaching a wafer, wherein a base film is constituted by a rubber-like elastic body made of a vulcanized product of the above. 2. A substrate comprising a natural rubber or isoprene rubber having a Young's modulus of 10 ^-1 to 10 ¹ MPa and a dimensional recovery of 90% or more, or a rubber-like elastic body made of a vulcanized product thereof. A wafer is stuck on an adhesive sheet for attaching a wafer, which is made up of a film and an adhesive layer, and the wafer is diced into element pieces (chips). After dicing, the adhesive sheet is transferred to a pickup device without expanding. A chip is picked up from a back surface of the adhesive sheet by a push-up pin and picked up by a suction collet.