JPH0532946A - Releasable tacky adhesive polymer - Google Patents

Abstract

PURPOSE:To provide the subject polymer containing a specific radiation- polymerizable functional group, having a radiation volume shrinkage higher than a prescribed level and excellent pasting workability, resistance and durability and useful for the pasting of small element chips. CONSTITUTION:The objective polymer having a volume shrinkage of >=0.5% by the irradiation of ultraviolet ray, etc., contains a polyfunctional monomer or oligomer having a radiationpolymerizable functional group and bonded to a side chain or main chain of a polymer of an acrylic acid ester, etc. (having a molecular weight of preferably 100,000-800,000), wherein said radiation- polymerizable functional group contains >=2 carboncarbon double bonds. A tacky adhesive sheet for the pasting of wafer and having high durability can be produced by applying the polymer to a substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a re-peelable pressure-sensitive adhesive polymer, and in particular, it is used for an adhesive layer of a pressure-sensitive adhesive sheet for wafer dicing, which is used when a semiconductor wafer is cut (diced) and separated into element pieces and the element pieces are picked up. Removable adhesive polymer.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION Semiconductor wafers such as silicon and gallium arsenide are manufactured in a large diameter state, and the wafer is cut (diced) into small pieces of an element and then transferred to a mounting step which is the next step. .. At this time, the semiconductor wafer is subjected to the steps of dicing, washing, drying, expanding, picking up, and mounting while being adhered to the adhesive sheet in advance.

The adhesive sheet used in the steps from the dicing step to the pickup step of such a semiconductor wafer has sufficient adhesive force to the wafer chip from the dicing step to the drying step, and the wafer is picked up at the time of picking up. It is desired that the chip has an adhesive strength such that the adhesive does not adhere to the chip.

As such a pressure-sensitive adhesive sheet, Japanese Patent Laid-Open No.
0-196,956 and JP-A-60-223,
In Japanese Patent No. 139, a low molecular weight compound having a photopolymerizable carbon-carbon double bond in the molecule, which can be three-dimensionally reticulated on the surface of a substrate by light irradiation (hereinafter may be referred to as a polyfunctional oligomer). A pressure-sensitive adhesive sheet coated with a pressure-sensitive adhesive containing is proposed. These proposals are pressure-sensitive adhesive tapes prepared by coating a radiation-curable pressure-sensitive adhesive on a radiation-transparent substrate. The radiation-curable compound (multifunctional oligomer) contained in the pressure-sensitive adhesive is cured by irradiation with radiation. It is based on the principle of giving a three-dimensional reticulated structure to the pressure-sensitive adhesive to significantly reduce its fluidity.

However, in the conventional pressure-sensitive adhesive sheets as exemplified above, the cohesive force before irradiation with radiation is low,
The workability at the time of sticking the wafer was poor, and the force applied from the horizontal direction was weak, and the deviation was likely to occur when dicing the wafer.

Further, since the adhesive main agent (acrylic polymer) and the radiation-curable compound (polyfunctional oligomer) are not completely compatible in the adhesive, the adhesive layer is completely formed even when radiation is applied. The adhesive did not harden, and glue was likely to adhere to the picked-up element chips (chips).

Furthermore, additives such as plasticizers contained in the base material migrate to the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive property is apt to deteriorate.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and it is intended to enhance cohesive force, improve workability of application, and improve resistance to horizontal stress. It is an object. The present invention also provides
The purpose is to prevent the occurrence of so-called adhesive residue, in which the adhesive is attached to the picked-up element small pieces (chips). A further object of the present invention is to improve durability against additives that migrate from the base material to the pressure-sensitive adhesive layer.

[0009]

SUMMARY OF THE INVENTION The removable pressure-sensitive adhesive polymer according to the present invention comprises a polymer having a side chain or a main chain bonded to a polyfunctional monomer or oligomer having a radiation-polymerizable functional group, and the radiation-polymerizable functional polymer. The group has two or more carbon-carbon double bonds, and the volume contraction rate by irradiation of radiation is 0.5%.
It is characterized by the above.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The removable pressure-sensitive adhesive polymer according to the present invention will be described in more detail below. The removable pressure-sensitive adhesive polymer according to the present invention has a radiation-polymerizable functional group derived from a polyfunctional monomer or oligomer bonded to the side chain or main chain of the polymer.

As the polymer to be the main chain, conventionally known polymers are widely used. Specifically, an acrylic-based polymer selected from homopolymers and copolymers containing acrylic acid ester as a main constituent monomer unit is used. Copolymers and copolymers with other functional monomers and mixtures of these polymers are used.
For example, acrylic acid ester, methacrylic acid ester, vinyl acetate ester, acrylonitrile, vinyl ethyl ether, etc. of alkyl alcohol having 1 to 10 carbon atoms can be preferably used. The above acrylic polymers may be used alone or in combination of two or more.

The polyfunctional monomer or oligomer introduced into the side chain or main chain of the above acrylic polymer to induce a radiation-polymerizable functional group is a photopolymerizable compound in a molecule which can be three-dimensionally reticulated by irradiation with light. Low-molecular-weight compounds having at least two carbon-carbon double bonds are widely used, and specifically, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol diacrylate. , Dipentaerythritol triacrylate,
Dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol dimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, etc. Used. The polyfunctional monomers or oligomers may be used alone or in combination of two or more.

The removable pressure-sensitive adhesive polymer according to the present invention is
An active site (eg, -C
It can be obtained by introducing OOH, —NCO, epoxy group, —OH, —NH ₂ ) and then reacting the active site with the polyfunctional monomer or oligomer.

In order to introduce the above-mentioned active sites into the polymer, it is necessary to perform "cleavage of a double bond" such as a carboxyl group, an isocyanate group, a hydroxyl group, an amino group or an epoxy group during the production of an acrylic polymer. A monomer or oligomer having both a functional group and a carbon-carbon double bond capable of reacting by different mechanisms may coexist in the reaction system. Specifically, the following compounds are used.

To introduce the --COOH group, acrylic acid, methacrylic acid, etc. are used. Methacryloyloxyisocyanate, acryloyloxyisocyanate and the like are used to introduce the —NCO group.

To introduce an epoxy group, glycidyl acrylate, glycidyl methacrylate, etc. are used. To introduce the —OH group, glycerol monoacrylate, glycerol monomethacrylate, 1,6-hexanediol monoacrylate, 1,6-hexanediol monomethacrylate, 2-hydroxyethyl acrylate, 2-hydroxymethacrylate and the like are used.

To introduce the --NH ₂ group, N-methyl acrylamide, N-methyl methacrylamide, etc. are used. Monomers that induce these active sites have 1
It is present in a proportion of .about.50 mol%, preferably 5 to 30 mol%.

Further, as described above, these active points react with the polyfunctional monomer or oligomer to provide the removable pressure-sensitive adhesive polymer according to the present invention. It is preferred to leave less than 2%. By leaving a small amount of active sites in this way, the cohesive force or adhesive force of the finally obtained re-peelable adhesive polymer may be improved.

The polyfunctional monomer or oligomer as described above is introduced into the side chain or main chain of the above-mentioned acrylic polymer via the active site, and has radiation having at least two carbon-carbon double bonds. The polymerizable functional group is induced to obtain the removable pressure-sensitive adhesive polymer according to the present invention.

As another method for producing the removable pressure-sensitive adhesive polymer according to the present invention, for example, a method of reacting a diol having two or more radiation-polymerizable carbon-carbon double bonds with a diisocyanate, a diol, Method of reacting diisocyanate having two or more radiation-polymerizable carbon-carbon double bonds, or diol having two or more radiation-polymerizable carbon-carbon double bonds and two or more radiation-polymerizable carbon- Examples thereof include a method of reacting with a diisocyanate having a carbon double bond. The removable pressure-sensitive adhesive polymer thus obtained is a urethane-based polymer having two or more radiation-polymerizable carbon-carbon double bonds in the main chain.

The molecular weight of the removable pressure-sensitive adhesive polymer according to the present invention as described above is about 1 × 10 ⁴ to 1 × 10 ⁶ , preferably about 1 × 10 ⁵ to 8 × 10 ⁵ . The volume of the removable pressure-sensitive adhesive polymer according to the present invention as described above is reduced by irradiation with radiation. The volume contraction rate by irradiation with radiation is 0.5% or more, preferably 1% or more.

The releasable adhesive polymer according to the present invention thus obtained has a high cohesive force. By using such a releasable adhesive polymer as an adhesive layer of a pressure-sensitive adhesive sheet for wafer sticking, sticking workability is improved. Also, a pressure-sensitive adhesive sheet for wafer sticking having excellent resistance to stress from the horizontal direction can be obtained. Such a pressure-sensitive adhesive sheet can prevent the generation of adhesive residue, and further has excellent durability against an additive that migrates from the base material to the pressure-sensitive adhesive layer.

The removable pressure-sensitive adhesive polymer according to the present invention comprises
Since it has the above-mentioned various properties, it is particularly suitably used as an adhesive for a pressure-sensitive adhesive sheet for wafer sticking. Wafer sticking pressure-sensitive adhesive sheet using the re-peelable pressure-sensitive adhesive polymer according to the present invention has high cohesive force of the pressure-sensitive adhesive, and thus has high sticking workability,
Further, since the resistance to the stress from the horizontal direction is high, the deviation is unlikely to occur during the dicing of the wafer. Further, in this pressure-sensitive adhesive, the radiation-polymerizable functional groups are distributed at the molecular level in the pressure-sensitive adhesive polymer, so that the polymer is uniformly cured by irradiation with radiation, so that the generation of adhesive residue can be prevented. Further, since this removable adhesive polymer has high durability against a plasticizer and the like, the adhesive property does not deteriorate even after long-term storage.

The removable adhesive polymer according to the present invention is
It is produced by reacting a polymer having active sites introduced with a polyfunctional monomer or oligomer. Specifically, for example, it can be obtained by reacting an acrylic acid ester with a compound capable of inducing active sites by a usual polymerization method and then reacting the obtained product with a polyfunctional monomer or oligomer.

The removable adhesive polymer according to the present invention is
As described above, it is preferably used as an adhesive layer of an adhesive sheet for wafer sticking. Hereinafter, the pressure-sensitive adhesive sheet for wafer sticking will be described more specifically.

The pressure-sensitive adhesive sheet 1 for wafer sticking is composed of a base material 2 and a pressure-sensitive adhesive layer 3, as shown in the sectional view of FIG. In order to protect the pressure-sensitive adhesive layer 3 before use, it is preferable to temporarily adhere the peelable sheet 4 to the upper surface of the pressure-sensitive adhesive layer 3 as shown in FIG. Further, an intermediate layer may be provided between the base material 2 and the pressure-sensitive adhesive layer 3 in order to further prevent migration of the plasticizer.

The pressure-sensitive adhesive sheet may have any shape such as a tape shape or a label shape. As the base material 2, a radiation-transparent base material is used. As such a base material, various materials have been conventionally known. For example, when ultraviolet rays are used as radiation, polyester, polyethylene, polypropylene, polybutene, polybutadiene, vinyl chloride, vinyl chloride copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer,
Examples thereof include resin-made base materials such as ethylene- (meth) acrylic acid ester copolymers, polystyrene, and polycarbonate, and further, base materials obtained by applying a silicone resin or the like to the surface of these resin-made base materials and subjecting them to release treatment. When an electron beam is used as the radiation, a fluororesin, a colored opaque film or the like is used.

As the base material 2, one kind of the above resin film may be used alone, or a laminated film formed by laminating two or more kinds may be used. The thickness of the above-mentioned substrate is usually 10 to 300 μm, preferably 50.
˜150 μm.

As will be described later, the adhesive sheet is irradiated with radiation such as electron beam (EB) or ultraviolet ray (UV) when used, but in the case of EB irradiation, the base material 2 is transparent. It is not necessary, but it needs to be transparent when used by UV irradiation.

The pressure-sensitive adhesive layer 3 is composed of the above-mentioned re-peelable pressure-sensitive adhesive polymer, but in addition to the polymer, a compound which is colored by irradiation with radiation can be contained. By including a compound to be colored in the pressure-sensitive adhesive 3 by such radiation, the pressure-sensitive adhesive sheet is colored after being irradiated with radiation, and therefore, the detection accuracy when the wafer chip is detected by the optical sensor is improved. Therefore, malfunction does not occur at the time of picking up a wafer chip. In addition, it is possible to obtain an effect that it is immediately visible by visual inspection whether or not the adhesive sheet is irradiated with radiation.

The compound that is colored by irradiation with radiation is a compound that is colorless or light-colored before irradiation with radiation, but is colored by irradiation with radiation, and a preferable specific example of this compound is a leuco dye. As the leuco dye, conventional triphenylmethane type, fluorane type, phenothiazine type, auramine type and spiropyran type dyes are preferably used. Specifically, 3- [N-
(P-Tolylamino)]-7-anilinofluorane, 3
-[N- (p-tolyl) -N-methylamino] -7-anilinofluorane, 3- [N- (p-tolyl) -N-ethylamino] -7-anilinofluorane, 3-diethylamino -6-Methyl-7-anilinofluorane, crystal violet lactone, 4,4 ', 4 "-trisdimethylaminotriphenylmethanol, 4,4', 4"
-Trisdimethylaminotriphenylmethane and the like.

Examples of the developers that are preferably used with these leuco dyes include conventionally used phenol formalin resin prepolymers, aromatic carboxylic acid derivatives, and electron acceptors such as activated clay. When changing the value, 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 contained in the adhesive layer, or may be made into a fine powder and contained in the adhesive layer. .. This compound is added to the adhesive layer in an amount of 0.01 to
It is desired to be used in an amount of 10% by weight, preferably 0.5-5% by weight. If the compound is used in an amount exceeding 10% by weight, the radiation applied to the pressure-sensitive adhesive sheet may be excessively absorbed by the compound, so that the pressure-sensitive adhesive layer may be insufficiently cured. Is less than 0.01% by weight, the pressure-sensitive adhesive sheet may not be sufficiently colored during irradiation with radiation, and malfunction may easily occur during pickup of the wafer chip.

In some cases, the light-scattering inorganic compound powder may be contained in the pressure-sensitive adhesive layer 3 in addition to the above-mentioned re-peelable pressure-sensitive adhesive polymer. By including such a light-scattering inorganic compound powder in the pressure-sensitive adhesive layer 3, 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 area, the adhesive force is sufficiently reduced, so that the adhesive does not adhere to the surface of the wafer chip at the time of picking up the wafer chip, and moreover, it has sufficient adhesion before the irradiation of radiation. The effect of having power is obtained.

This light-scattering inorganic compound is
V) or an electron beam (EB) or the like, which is a compound capable of diffusely reflecting this radiation, and specifically, silica powder, alumina powder, silica-alumina powder, mica powder Are exemplified. The light-scattering inorganic compound is preferably a compound that almost completely reflects the above-mentioned radiation, 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 powder and has a particle size of 1 to 100 μm, preferably 1 to 100 μm.
It is preferably about 20 μm. It is desirable that the light-scattering inorganic compound is used in the pressure-sensitive adhesive layer in an amount of 0.1 to 10% by weight, preferably 1 to 4% by weight. When the compound is used in the adhesive layer in an amount exceeding 10% by weight,
The adhesive strength of the pressure-sensitive adhesive layer may decrease. On the other hand, when the content is less than 0.1% by weight, when the semiconductor wafer surface turns gray or black, the adhesive strength is sufficient even if the area is irradiated with radiation. The adhesive may remain on the surface of the wafer at the time of picking up.

The pressure-sensitive adhesive sheet obtained by adding the light-scattering inorganic compound powder to the pressure-sensitive adhesive layer can be used even when the surface of the semiconductor wafer is grayed or blackened for some reason. It is considered that the reason why the adhesive force of this part, when it is irradiated with radiation, is sufficiently lowered in this part is as follows. That is, the pressure-sensitive adhesive sheet 1 has the pressure-sensitive adhesive layer 3, but when the pressure-sensitive adhesive layer 3 is irradiated with radiation, the radiation-polymerizable compound contained in the pressure-sensitive adhesive layer 3 cures and its adhesive force decreases. It will be. However, a grayed or blackened portion may occur on the semiconductor wafer surface for some reason. When the adhesive layer 3 is irradiated with radiation in such a case, the radiation passes through the adhesive layer 3 and reaches the wafer surface. However, if there is a grayed or blackened portion on the wafer surface, the radiation will be emitted at this portion. Absorbed,
It will not be reflected. For this reason, radiation that should originally be used for curing the pressure-sensitive adhesive layer 3 is absorbed in the grayed or blackened portion, and the curing of the pressure-sensitive adhesive layer 3 becomes insufficient, so that the adhesive strength is not sufficiently reduced. become. Therefore, it is considered that the adhesive may 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 3, the irradiated radiation collides with the compound and changes its direction before reaching the wafer surface. For this reason, even if there is a grayed or blackened portion on the wafer chip surface, the diffusely reflected radiation sufficiently enters the area above this portion, and thus the grayed or blackened portion is also sufficiently cured. To do. For this reason,
By adding the light-scattering inorganic compound powder to the adhesive layer, even if there is a grayed or blackened portion on the surface of the semiconductor wafer for some reason, curing of the adhesive layer becomes insufficient at this portion. Therefore, the adhesive does not adhere to the chip surface when the wafer chip is picked up.

Further, abrasive grains may be dispersed in the base material. The abrasive grains have a particle size of 0.5 to 100 μm, preferably 1 to 50 μm, and a Mohs hardness of 6 to 10, preferably 7 to 10. Specifically, 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 present in the base material 2 in an amount of 0.5 to 70% by weight, preferably 5 to 50% by weight. Such abrasive grains are particularly preferably used when the cutting blade is used at a depth that cuts not only the wafer but also the base material 2.

By including the above-mentioned abrasive grains in the base material, the cutting blade can cut into the base material, and even if an adhesive is attached to the cutting blade, the abrasive effect of the abrasive grains can easily cause clogging. Can be removed.

Also, a small amount of active sites remaining in the above-mentioned adhesive
Is -COOH group, -OH group, -NH ₂If it is a group
To mix the isocyanate hardener into the adhesive
Allows you to set the initial adhesive strength to any value.
It As such a curing agent, specifically, a polyvalent isocyanate is used.
Anate compounds such as 2,4-tolylene diisocyanate
Nate, 2,6-tolylene diisocyanate, 1,3-
Xylylene diisocyanate, 1,4-xylene diiso
Cyanate, diphenylmethane-4,4'-diisocyanate
, Diphenylmethane-2,4'-diisocyanate
G, 3-methyldiphenylmethane diisocyanate,
Xamethylene diisocyanate, isophorone diisocyanate
Nate, dicyclohexylmethane-4,4'-diisocyanate
Anate, dicyclohexylmethane-2,4'-diiso
Cyanate, lysine isocyanate, etc. are used.

When the active site is a -NCO group,
As a curing agent, diols such as glycol, cresol, hexamethylene diol, trimethylol propane are used.

When the active site is an epoxy group,
As the curing agent, amines such as hexamethylenediamine and ethylenetetraamine are used. Furthermore, in the case of UV irradiation, the UV-initiator is mixed in the above-mentioned pressure-sensitive adhesive so that the polymerization curing time and UV
The irradiation dose can be reduced.

Specific examples of such UV initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
Examples thereof include benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl and β-chloranthraquinone.

As described above, in the pressure-sensitive adhesive sheet for wafer sticking, in order to protect the pressure-sensitive adhesive layer 3 before use,
As shown in FIG. 2, it is preferable to temporarily adhere the peelable sheet 4 to the upper surface of the pressure-sensitive adhesive layer 3. As the peelable sheet 4, a conventionally known sheet is used without particular limitation.

Next, a method for dicing a wafer using the above-mentioned pressure-sensitive adhesive sheet for wafer attachment will be described. When the peelable sheet 4 is provided on the upper surface of the pressure-sensitive adhesive sheet 1, the sheet 4 is removed, and then the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1 is placed face up, as shown in FIG. Then, the semiconductor wafer A to be diced is attached to the upper surface of the adhesive layer 3. Wafer A in this attached state
The process of dicing, washing, and drying is added to. At this time, since the wafer chip is sufficiently adhered and held on the adhesive sheet by the adhesive layer 3, the wafer chip does not fall off during 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. 5, radiation B such as ultraviolet rays (UV) or electron beams (EB) is applied to the pressure-sensitive adhesive layer 3 of the pressure-sensitive adhesive sheet 1, and the pressure-sensitive adhesive layer 3 The removable adhesive polymer contained therein is polymerized and cured.

The radiation of 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. Therefore, as described above, when UV is used as the radiation, the base material 2 needs to be light transmissive, but when EB is used as the radiation, the base material 2 does not necessarily have to be light transmissive. Absent.

When irradiating with radiation, the adhesive layer of the portion to which the wafer is attached (hereinafter sometimes referred to as the wafer attaching portion) is the portion to which the wafer is not attached. It is preferable to irradiate a relatively small amount of radiation with respect to the amount of radiation applied to the pressure-sensitive adhesive layer (hereinafter, may be referred to as a wafer non-sticking portion). Conventionally, the entire surface of the pressure-sensitive adhesive layer was irradiated uniformly, but if the entire surface is irradiated in this way, the following problems may occur when the tape is stretched in the expanding process. Found by the applicant. That is, since the expansion rate (elongation rate) of the wafer sticking portion in the expanding step is lower than the expansion rate of the wafer non-sticking portion, when the expanding is performed, only the wafer non-sticking portion is preferentially expanded. Therefore, it has been difficult to obtain a desired chip interval.
Therefore, the radiation dose applied to the wafer sticking part is 1 to 90%, preferably 5 to 60%, and particularly preferably 5 to 60% of the radiation dose to the wafer non-sticking part.
30% is desirable.

When the adhesive layer 3 is irradiated with radiation to polymerize and cure the removable adhesive polymer in this manner, the adhesive force of the wafer adhering portion is lowered to such an extent that the wafer can be picked up. The expansion rate does not decrease much. On the other hand, since a large amount of radiation is applied to the non-wafer-bonded portion, the curing proceeds sufficiently and the expansion rate is significantly reduced. As a result, in the expanding step, only the part to which the wafer is not attached is not preferentially extended, and the part to which the wafer is attached is also extended, so that a desired chip interval can be obtained. It will be easier.

As described above, in order to control the amount of radiation applied to the wafer adhering portion and the amount of radiation applied to the non-wafer adhering portion, for example, the same amount as that of the wafer adhered to the adhesive tape is used. A layer that absorbs or reflects radiation is formed on the base material of the adhesive tape or between the base material and the adhesive layer, or has a shape almost the same as that of the wafer attached to the adhesive tape. However, a filter that absorbs or reflects radiation may be provided in the radiation irradiation unit of the radiation irradiation device.

After the expanding step, as shown in FIG. 6, the chips A ₁ , A ₂ ... A to be picked up from the lower surface of the base material 2 by the push-up needle bar 5 according to a conventional method.
₅ is pushed up, this chip A ₁ ... is picked up by, for example, a suction collet 6, and this is mounted on a predetermined base. In this way, the wafer chips A ₁ , A ₂
When picked up, the chips can be picked up easily because a sufficient chip interval is obtained, and the adhesive force is sufficiently reduced, so good chips without contamination can be obtained. Be done.

[0053]

As described above, the removable pressure sensitive adhesive polymer according to the present invention has a high cohesive force, and such removable pressure sensitive adhesive polymer is used as the pressure sensitive adhesive layer of the pressure sensitive adhesive sheet for wafer sticking. As a result, a pressure-sensitive adhesive sheet for wafer sticking, which has excellent sticking workability and resistance to stress from the horizontal direction, can be obtained. Such a pressure-sensitive adhesive sheet can prevent the generation of adhesive residue, and further has excellent durability against an additive that migrates from the base material to the pressure-sensitive adhesive layer.

[0054]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition, in the following examples, the adhesive force, the holding force, and the adhesive residue were measured according to the following methods. Adhesion: Measured according to JIS Z 0237. Holding power: measured according to JIS Z 0237. Adhesive residue: (1) Inspection device Laser inspection device LS-5000 manufactured by Hitachi Electronics (2) Sample 5 inch mirror wafer UV tape was attached to the mirror surface so that air bubbles did not enter, and U within 2 hours
UV irradiation (irradiance: 150 to 200 mW / cm ² , irradiation time: 2 seconds or more), and the UV tape was peeled off within 24 hours after irradiation.

[0055]

Example 1 60 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of glycidyl methacrylate and 25 parts by weight of isocyanate ethyl methacrylate are reacted in a general polymerization recipe. To the product obtained in this reaction, 48 parts by weight of pentaerythritol triacrylate is added and reacted at 40 ° C. for 5 hours. To 100 parts by weight of the obtained polymer, 1 part by weight of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) was added as a cross-linking agent, and IRGACURE 651 (manufactured by Nippon Ciba Geigy) was added as a UV initiator to obtain an adhesive composition. To create.

This adhesive composition was placed on a release sheet for 10 minutes.
Apply to a thickness of μm, dry, and transfer onto polyethylene to make an adhesive tape. A silicon wafer whose one surface is mirror-finished is attached to the obtained adhesive tape, and the adhesive force and holding force before and after irradiation with radiation are measured by the above-mentioned methods. The adhesive strength before irradiation is sufficiently high, but it decreases significantly after irradiation. The holding power does not change significantly before and after irradiation. Almost no adhesive residue is observed.

[0057]

Comparative Example 1 80 parts by weight of butyl acrylate, 13 parts by weight of 2-ethylhexyl acrylate, and 7 parts by weight of glycidyl methacrylate were reacted, and 1 part by weight of Coronate L (Japan Polyurethane Co., Ltd.) is added as a crosslinking agent to prepare an adhesive composition. A very large amount of glue residue is observed.

[0058]

Comparative Example 2 60 parts by weight of butyl acrylate, 10 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of glycidyl methacrylate, and 25 parts by weight of isocyanate ethyl methacrylate are reacted. To the product obtained by this reaction, 48 parts by weight of pentaerythritol triacrylate and 1 part by weight of Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) are added as a crosslinking agent to prepare a pressure-sensitive adhesive composition. A large amount of adhesive residue is observed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pressure-sensitive adhesive sheet using a removable pressure-sensitive adhesive polymer according to the present invention as a pressure-sensitive adhesive layer.

FIG. 2 is a cross-sectional view of a pressure-sensitive adhesive sheet using the removable pressure-sensitive adhesive polymer according to the present invention as a pressure-sensitive adhesive layer.

FIG. 3 is a cross-sectional view showing a state in which a wafer is bonded to a pressure-sensitive adhesive sheet using the removable pressure-sensitive adhesive polymer according to the present invention as a pressure-sensitive adhesive layer.

FIG. 4 is a cross-sectional view showing a state where the wafer is diced.

FIG. 5 is a view showing a state in which a diced wafer is irradiated with radiation.

FIG. 6 is an explanatory diagram of a pickup process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 2 ... Substrate 3 ... Adhesive layer 4 ... Peelable sheet 5 ... Push-up needle bar 6 ... Suction collet A ... Wafer B ... Radiation

Claims (1)

Claim: What is claimed is: 1. A side chain or a main chain of a polymer is bound to a polyfunctional monomer or oligomer having a radiation-polymerizable functional group, the radiation-polymerizable functional group being a carbon-carbon diamine. A removable pressure-sensitive adhesive polymer having two or more heavy bonds and having a volume contraction rate of 0.5% or more upon irradiation with radiation.