JPH0823001B2 - Adhesive film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to automatic collection by a pickup method after cutting a semiconductor wafer under adhesive fixation and then holding formed small pieces of an element under weak adhesion and stretching a film-like support. An adhesive film made possible.

2. Description of the Related Art As a method for cutting and separating a semiconductor wafer on which a predetermined circuit pattern is formed into element pieces in a semiconductor wafer manufacturing process, a direct pickup method is known, which is an alternative to the V-order groove engraving and dividing method up to then. . This method is intended to improve the workability by enabling automatic processing of cutting and separating the semiconductor wafer, and an adhesive film is attached to the semiconductor wafer in advance, and this film is cut by a cutting means such as a rotary round blade. Fix the element small piece obtained by cutting the wafer along the element shape, then add physical means such as pushing up this element small piece with a needle etc. from the adhesive film and adsorb it with air tweezers etc. and separate it from the film The content is to let.

BACKGROUND ART Conventionally, as an adhesive film for fixing an element piece obtained by cutting a semiconductor wafer in a direct pickup method, a type in which the adhesive force cannot be controlled before and after cutting the semiconductor wafer has been known. . In other words, there is no known adhesive film that has sufficient adhesive force to hold the element chip when cutting the semiconductor wafer and can reduce the adhesive force after the cutting so as to favorably separate the element piece. .

Problems to be Solved by the Invention Adhesive force conditions desired for the above-mentioned fixing adhesive film in the direct pickup method are cooling of the semiconductor wafer at the time of cutting, element small piece holding capable of withstanding water pressure of water discharge for cutting waste removal, etc. That is, it has a force, and the force required for separating the element piece from the adhesive film at the time of pickup is small.

In the conventional adhesive film, the above adhesive force condition is achieved by setting the element piece holding force to the necessary minimum. However, the minimum necessary holding force of the element piece increases according to the size of the element piece, and accordingly, the force required for separating the element piece also increases with the increase. Therefore, there is a problem that it is necessary to increase the separating force. This problem is a technology that can be applied when the area of the element small pieces is up to about 20 mm ^2, and the size of the element small pieces has been increased due to the recent increase in the degree of integration. It has come to be seen as a practical problem that it cannot deal with things over 50 mm ² such as.

On the other hand, in the conventional adhesive film, there is a problem that when the element small piece is picked up from the adhesive film, the adjacent element small piece is contacted and damaged due to the small gap between the cut and separated element small pieces.

Means for Solving the Problems The present invention makes the adhesive force of an adhesive film variable, and
It is intended to provide a film which overcomes the above problems by giving the film uniform stretchability.

That is, the adhesive film of the present invention comprises a translucent and stretchable film-like support provided with a pressure-sensitive adhesive layer which is cured by light irradiation to form a three-dimensional network structure. It consists of a plastic film with rubber elasticity that stretches the body evenly by stretching and contracts to 1.5 times or less of the original length within 1 minute after stretching 2 times for 1 minute, and the pressure-sensitive adhesive layer before light irradiation. At 10 kg
/ cm ² or less, 20 kg / cm ² or more after curing by light irradiation
It exhibits 100% modulus and the gel fraction after curing by light irradiation is more than 1.4 times that before light irradiation, 55% by weight or more, and the 180 degree peeling force to the semiconductor wafer is 200 ~ 1000g / before light irradiation. 20 mm, 5 to 125 g / 50 mm after curing by irradiation with light, the semiconductor wafer is cut under adhesive fixation, and after that, the small pieces of the forming element are picked up under weak adhesion retention and extension of the film-like support. It is for automatic collection by the method.

Action With the above configuration, the adhesive force of the pressure-sensitive adhesive layer can be reduced based on the light irradiation, and the adhesive force to the wearer can be controlled, and the film can be stretched and worn. It is possible to widen the gap between the bodies. As a result, when the semiconductor wafer is cut into element pieces, it can be held and fixed with a sufficient adhesive force, and the element pieces formed by the appropriate decrease in the adhesive force due to light irradiation can form a 50 mm ² element piece.
Even when it exceeds, it can be easily collected by the direct pickup method while holding it without dropping. In addition, at that time, the film can be stretched to widen the gap between the element pieces, and damage due to contact of the element pieces during pickup can be prevented.

Examples of Constituent Elements of the Invention As the film-like support in the adhesive film of the present invention, a plastic film which is translucent, stretchable and has rubber elasticity capable of being uniformly stretched by stretching is used. By being able to stretch it evenly, it is possible to make the spacing between the element pieces uniform after cutting and separating the semiconductor wafer, and when the element pieces are separated from the adhesive film, contact between the element pieces (causing damage to the element pieces It becomes easy to control the stretching process for preventing A film-like support that can be preferably used is one having a rubber elasticity represented by, for example, polybutene, polyurethane, and 1,2-polybutadiene, and is excellent in transparency. Here, rubber elasticity means the property that the material stretches to double its length at room temperature, holds for 1 minute, talks, and then shrinks to a length shorter than 1.5 times the original length within 1 minute. To do. The thickness of the film-like support is usually 10 to 300 μm from the viewpoint of strength, light transmission amount and the like.

The pressure-sensitive adhesive layer provided on the film-like support and cured by light irradiation to form a three-dimensional network structure includes, for example, a rubber-based or acrylic-based pressure-sensitive adhesive with at least two light rays in a molecule. Examples thereof include a composition prepared by blending a low molecular weight compound having a polymerizable carbon-carbon double bond (hereinafter referred to as a photopolymerizable compound) and a photopolymerization initiator.

More specifically, as the pressure-sensitive adhesive, for example, a rubber-based polymer such as natural rubber or various synthetic rubbers, or poly (meth) acrylic acid alkyl ester, or (meth) acrylic acid alkyl ester is used in an amount of about 50 to 99.5% by weight Other unsaturated monomer copolymerizable with about 50 to 0.5% by weight of an acrylic polymer such as a copolymer is used as a base polymer, and if necessary, a polyisocyanate compound, an alkyl etherified melamine compound, etc. Examples thereof include those containing about 0.1 to 10 parts by weight of a crosslinking agent (per 100 parts by weight of the base polymer). The base polymer may have a photopolymerizable carbon-carbon double bond in its molecule. In this case, it may be possible to perform a sufficient degree of curing treatment (decrease in adhesive strength) without blending the following photopolymerizable compound.

As the photopolymerizable compound, one having a molecular weight of 10,000 or less is usually suitable, and preferably a molecular weight of 5,000 or less and 2 to 6 photopolymerizable carbon-carbon double bonds in the molecule, especially 3
It has ~ 6 pieces. This is because the formation efficiency of the three-dimensional reticulated structure is excellent. Typical examples of preferable photopolymerizable compounds include trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate and dipentaerythritol hexaacrylate. Examples of other photopolymerizable compounds include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and polyethylene glycol diacrylate.
Further, commercially available oligoester acrylate and the like can be mentioned.

The photopolymerizable compound may be used alone or in combination of two or more, and the compounding amount thereof is usually 1 to 100 parts by weight per 100 parts by weight of the above base polymer. If the blending amount is too small, the three-dimensional reticulation of the pressure-sensitive adhesive layer due to light irradiation becomes insufficient, and the degree of decrease in the adhesive force to the element piece after curing becomes too small, which is not preferable. On the other hand, if the blending amount is too large, the pressure-sensitive adhesive layer is remarkably plasticized and a sufficient adhesive force cannot be obtained, which is not preferable.

Examples of the photopolymerization initiator include isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, acetophenone diethyl ketal, benzyl dimethyl ketal, α-hydroxycyclohexene. Nylphenyl ketone, 2-hydroxymethylphenyl propane, etc. may be used, and one kind may be used alone or two or more kinds may be used in combination.

The amount of the photopolymerization initiator is usually 100
Appropriately 0.1 to 5 parts by weight per part by weight. If the blending amount is too small, three-dimensional reticulation of the pressure-sensitive adhesive layer due to light irradiation becomes insufficient, and the degree of reduction in the adhesive force to the element piece becomes too small, which is not preferable. On the other hand, if the blending amount is too large, the photopolymerization initiator may remain on the surface of the element piece, which may be inconvenient.

In the present invention, a photopolymerization accelerator such as an amine compound such as triethylamine, tetraethylpentaamine, dimethylaminoethanol may be used in combination.

The pressure-sensitive adhesive layer can be formed, for example, by a method of applying the adhesive composition on the above-mentioned film-shaped support and subjecting it to heat treatment if necessary. The thickness of the pressure sensitive adhesive layer is usually about 5 to 70 μm.

The pressure-sensitive adhesive layer has a 100% modulus (20 ° C.) of 10 kg / cm ² or less before light irradiation, preferably 0.5, from the viewpoint of the adhesive strength before light irradiation and the degree of decrease in adhesive strength due to light irradiation. a ~8kg / cm ^2, in the case of three-dimensionally reticulated by curing by light irradiation 20 kg / cm ² or more, preferably
It is 25 to 150 kg / cm ² , more preferably 28 to 100 kg / cm ² . On the other hand, from the viewpoint of the gel fraction and the degree of swelling of the gel, the gel fraction when immersed in toluene (20 ° C.) for 24 hours is less than 55% by weight before light irradiation, preferably 0.
5 to 55% by weight, more preferably 35 to 55% by weight, 55% by weight or more, preferably 60% by weight or more, more preferably 70% by weight when cured by light irradiation to form a three-dimensional mesh.
It is more than 1.4 times before light irradiation, also the degree of swelling of the gel is 20 times or more before light irradiation, preferably 25 to 80 times, when cured by light irradiation and three-dimensional reticulated 18 times or less, preferably 5 to 15 times.

The adhesive film of the present invention is, for example, a semiconductor wafer in the case of cutting a semiconductor wafer on which a predetermined circuit pattern is formed in a semiconductor wafer manufacturing and assembling process into element pieces and collecting the obtained element pieces or fixing of the element pieces. It is used as a film for business.

 The use is performed as follows, for example.

That is, taking the case of the above-mentioned semiconductor wafer as an example, first, a semiconductor wafer having a predetermined circuit pattern formed thereon is attached and fixed to an adhesive film, and then the wafer is cut into element pieces by a cutting means such as a rotary round blade. Cut and split. Then, after spreading the film with the element piece attached and stretching it, from the film-like support side, for example, a light with a wavelength of 180 to 460 nm by a high pressure mercury lamp or an ultrahigh pressure mercury lamp is usually irradiated for about 2 to 180 seconds and then sensed. The pressure-sensitive adhesive layer is cured to form a three-dimensional network structure. It is considered that this three-dimensional reticulation proceeds by photopolymerizable compounds being polymerized by irradiation with light and radicals are also generated in the base polymer to react with this polymer and the photopolymerizable compound. The original reticulation increases the cohesive force of the adhesive layer, and on the basis of this, the adhesive force or adhesive force of the adhesive layer decreases. Subsequently, the element pieces whose gaps have been increased by stretching the film are picked up and collected by a method such as pushing up with a needle or the like from the film whose adhesive strength has been reduced by light irradiation and adsorbing with air tweezers.

Although the adhesive film of the present invention can be applied to a semiconductor wafer as described above, the adhesive force of the adhesive film to a semiconductor wafer when applied to a semiconductor wafer is 180 ° peeling adhesive force. (Peeling speed 3
200-1000g / 20mm before light irradiation based on (00mm / min)
It is 5 to 125 g / 20 mm after irradiation with light, which may exceed ² kg / cm ² , for example, the property of preventing element small pieces from falling off due to water pressure during wafer cutting, and the size being 50 mm.
It is suitable from the point of picking up element small pieces that may exceed ² , that is, holding the formed element small pieces without falling off with adhesive strength that is easy even after light irradiation but requires a pickup process. is there. It is inconvenient that the light-irradiation reduces the adhesive strength to such an extent that the formed element small pieces fall off, and when the adhesive film is stretched, the element small pieces are likely to fall off or collide with each other to cause damage or the like.

EFFECTS OF THE INVENTION According to the present invention, when a semiconductor wafer is cut into element pieces, the element pieces can be held and fixed with a sufficient adhesive force, and the formed element pieces can be prevented from falling off from the fixing film by the water pressure of washing water. Moreover, the adhesive force can be appropriately reduced by light irradiation, and even when the element small piece to be formed exceeds 50 mm ² , it can be easily collected by the direct pickup method while holding it without falling off. ,
The film can be stretched to widen the gap between the element pieces, and damage due to contact of the element pieces during pickup can be prevented.

EXAMPLES In the following, parts are parts by weight.

Example 1 A compounded composition consisting of 100 parts of butyl acrylate, 5 parts of acrylonitrile and 5 parts of acrylic acid was copolymerized in toluene to obtain an acrylic copolymer having a number average molecular weight of 300,000.

To 100 parts of this copolymer, 5 parts of a polyisocyanate compound (trade name Coronate L manufactured by Nippon Polyurethane Company), 15 parts of dipentaerythritol monohydroxypentaacrylate
Parts and 1 part of α-hydroxycyclohexylphenyl ketone were added and mixed to prepare a pressure-sensitive adhesive composition.

This composition was applied to one surface of a polybutene film having a thickness of 50 μm so that the adhesive layer had a thickness of 10 μm, and heated at 90 ° C. for 3 minutes to obtain an adhesive film.

Next, the adhesive surface of the obtained adhesive film has a diameter of 10 cm,
A semiconductor wafer having a thickness of 0.25 mm was attached and fixed via the back surface of the pattern formation surface. After that, the wafer was cut into 75 mm ² element pieces using a rotary round blade. Disconnect
It was washed while being washed with water having a water pressure of ² kg / cm ² , but the element pieces were not peeled or dropped, and the position was not displaced. In addition,
At this time, the gap between the element pieces was about 0.05 mm.

Then, spread the adhesive film with the element pieces attached and stretch it evenly 1.5 times in the circumferential direction, and fix it, and then apply a high pressure mercury lamp (40W / cm) from the support side of the adhesive film at a distance of 15 cm for 20 minutes. After radiating light for a second to crosslink and cure the adhesive layer, the element pieces were picked up by a method of adsorbing them with air tweezers while pushing them up one by one with a needle. At this time, the element pieces having a uniform gap of about 0.5 mm could be easily peeled off and collected without tearing or tearing the film, and the pickup property was good.

Example 2 Polyisocyanate compound (same as in Example 1) 5 in 100 parts of acrylic copolymer (same as in Example 1)
Parts, 20 parts of pentaerythritol toy acrylate and 0.5 parts of isobutyl benzoin ether were added and mixed to prepare a pressure sensitive adhesive composition. Using this composition, an adhesive film was obtained in the same manner as in Example 1, and the semiconductor wafer was fixed, cut, and the element pieces thereof were picked up. As a result, good workability was exhibited.

Comparative Example 1 An adhesive film for comparison was obtained in the same manner as in Example 1 except that 15 parts of dipentaerythritol monohydroxypentaacrylate and 1 part of α-hydroxycyclohexylphenyl ketone were not used, and a semiconductor wafer was fixed.
Upon cutting and picking up the element pieces, the element pieces could not be picked up, and the element pieces remained attached to the adhesive film.

Comparative Example 2 The same as Example 1 except that a biaxially stretched polyester film having substantially no elasticity was used as a support for the pressure-sensitive adhesive layer, and light irradiation and pickup treatment were performed without stretching treatment. An adhesive film was obtained with the adhesive film, the semiconductor wafer was fixed and cut, and the element pieces were picked up. As a result, element pieces having damage due to contact between the element pieces at the time of pickup were recognized.

Evaluation Test <180 Degree Peel Adhesion> The 180 degree peel adhesion (peel rate 300 mm / min) of the adhesive films used in Examples 1 and 2 and Comparative Example 1 above to the back surface of the semiconductor wafer was measured. The adhesive film was attached to the back surface of the semiconductor wafer and irradiated with light from a high pressure mercury lamp (40 W / cm) at a distance of 15 cm for 20 seconds from the support side, and then the adhesive strength was measured.

<100% Modulus> The pressure-sensitive adhesive compositions used in Examples 1 and 2 and Comparative Example 1 above were each subjected to a peeling treatment, and the surface of a polyethylene terephthalate film having a thickness of 50 μm had a thickness of 10 μm.
It is coated so that it becomes m and heated at 90 ℃ for 3 minutes, then 50
A filament-shaped test piece having a cross-sectional area of 0.5 mm ² was obtained by cutting it into a size of mm × 50 mm and collecting it into a rod shape. For this test piece, 100% module at 20 ° C. was measured. Also,
This test piece was irradiated with light under the same conditions as above, and then the same 100% 4 module was measured.

<Gel Fraction, Gel Swelling Degree> After coating and heating each of the above pressure-sensitive adhesive compositions in the same manner as in the case of 100% test pieces for module, 50 mm ×
A test piece was cut into a size of 500 mm. The test piece was immersed in toluene for 24 hours to examine the gel fraction and the gel swelling degree. Further, this test piece was irradiated with light under the same conditions as above, and then immersed in toluene for 24 hours to examine the gel fraction and the degree of swelling of the gel.

The above test results are shown in the table below. In the table below, column A shows measured values before light irradiation, and column B shows measured values after light irradiation.

As is clear from the above examples, when the adhesive film of the present invention is used for fixing a semiconductor wafer, the wafer or the element piece is held with a large adhesive force so that the element piece is not peeled off or displaced during cutting. On the other hand, at the time of pickup, the adhesive force can be reduced by light irradiation processing, and the gap between the element pieces can be widened, so that the element pieces can be easily picked up without being damaged.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seishiro Matsuzaki 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Prefecture Nitto Electric Industry Co., Ltd. (72) Eiji Shigemura 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Prefecture No. Nitto Electric Industry Co., Ltd. (56) Reference JP-A-53-121832 (JP, A) JP-A-51-90565 (JP, A) JP-A-49-123578 (JP, A) JP-A-53- 235 (JP, A)

Claims (3)

[Claims] 1. A light-transmitting and stretchable film-like support provided with a pressure-sensitive adhesive layer which is cured by light irradiation to form a three-dimensional network structure, and the film-like support is stretched. It is made of a plastic film with rubber elasticity that stretches uniformly and contracts to 1.5 times or less of the original length within 1 minute after stretching 2 times for 1 minute, and the pressure-sensitive adhesive layer is 10 kg / cm ² or less, shows a 100% modulus of 20 kg / cm ² or more after curing by light irradiation, and the gel fraction after curing by light irradiation is 1.
It is more than 4 times, 55% by weight or more, and the 180 degree peel adhesion to the semiconductor wafer is 200 to 1000 before light irradiation.
g / 20 mm, 5 to 125 g / 20 mm after curing by light irradiation, after cutting the semiconductor wafer under adhesive fixation, holding the small pieces of the forming element under weak adhesion and stretching the film-like support. Adhesive film for automatic collection by pickup method. 2. The film according to claim 1, wherein the film-shaped support has a thickness of 10 to 300 μm. 3. A pressure-sensitive adhesive layer comprising 100 parts by weight of a base polymer, 1 to 100 parts by weight of a low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule, and 0.1 to 5 of a photopolymerization initiator. The film according to claim 1, which comprises a pressure-sensitive adhesive composition containing parts by weight.