JP2983721B2 - Adhesive tape for fixing semiconductor wafers - 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 tape used in a process for manufacturing various semiconductors. More specifically, for example, a wafer on which a pattern is formed is cut into individual patterns and divided into semiconductor elements. The present invention relates to a radiation-curable pressure-sensitive adhesive tape for fixing a semiconductor wafer used at the time.

[0002]

2. Description of the Related Art Conventionally, a pickup method using a radiation-curable pressure-sensitive adhesive tape has been proposed for performing a dicing process for cutting and separating a semiconductor wafer on which a circuit pattern is formed into element pieces.

This is radiation, for example light such as ultraviolet light,
Or a method using a pressure-sensitive adhesive tape for fixing a semiconductor wafer comprising a base film that transmits ionizing radiation such as an electron beam, and a pressure-sensitive adhesive layer coated on the base film and having a property of being cured by irradiation with radiation. It is. More specifically, the element fixing adhesive force at the time of dicing processing is made to be a strong adhesive force, and after cutting and separating the semiconductor wafer into element pieces, irradiation is performed from the base film side to cure the radiation-curable adhesive layer, This is a method in which the element fixing adhesive force is greatly reduced so that a large element of, for example, 25 mm ² or more can be easily picked up regardless of the size of the element piece. In this method, a radiation-curable compound contained in an adhesive layer of a semiconductor wafer fixing adhesive tape in which a radiation-curable adhesive is coated on a radiation-transparent base film is cured by irradiation with radiation, and the adhesive is tertiarily cured. It is based on the principle of providing a primary reticulated structure and significantly reducing its fluidity and adhesion.

However, in such an adhesive tape, the adhesive is cured by a curing reaction of a radiation-curable compound to give a three-dimensional network structure and reduce the adhesive strength. As a result, the shape elasticity is almost lost during pickup. For this reason, it may not be possible to enlarge the element gap by the conventional radial stretching of the adhesive tape.

[0005] In order to solve this problem, a material in which soft polyvinyl chloride (PVC) is used as a central layer of a substrate film has already been put into practical use. In some cases, chlorine ions, metal ions, plasticizers, etc. migrate to cause contamination of the surface of the semiconductor wafer due to the inclusion of such stabilizers and plasticizers.

Therefore, as disclosed in JP-A-63-17980, radiation-curing is performed on a base film made of a polymer containing a compound having a carboxyl group as a polymer constituent unit such as an ethylene-acrylic acid copolymer. A pressure-sensitive adhesive tape coated with a hydrophilic pressure-sensitive adhesive has been proposed. However, when this adhesive tape is divided into small chips of about 3 × 3 mm, stretching before irradiation can expand the element gap enough to prevent contact between the elements, but after irradiation, In stretching, it has been difficult to obtain a large and uniform gap amount of element pieces required in a pickup device with image recognition. In addition, when the film was stretched after irradiation with radiation, the film was insufficient in properties such as breakage due to deterioration of the base film due to irradiation.

On the other hand, as disclosed in JP-A-2-215528, a thermoplastic resin having rubber-like elasticity, for example,
Polybutene-1, polyurethane, polyester elastomer, 1,2-polybutadiene, hydrogenated styrene-isoprene-styrene copolymer, or laminated film having styrene-ethylene-butene-styrene copolymer (SEBS) as a central layer Adhesive tapes as base films have been proposed. However, these adhesive tapes also require the necking of the base film itself (film stretching) in order to obtain a large and uniform gap amount of element pieces required in a pickup device with image recognition even after stretching after irradiation of radiation. In some cases, partial elongation occurs due to poor force transmission), and rubber-like elasticity is lost due to deterioration of the base film due to irradiation, and the properties are still insufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive tape for fixing a semiconductor wafer which has solved the above-mentioned problems. That is, the present invention maintains the rubber-like elasticity (flexibility) of the pressure-sensitive adhesive tape after radiation irradiation, and at the same time, prevents breakage due to deterioration of the base film due to radiation irradiation, and greatly increases the element gap by stretching the pressure-sensitive adhesive tape after radiation irradiation. An object of the present invention is to provide an adhesive tape for fixing a semiconductor wafer, which is capable of performing uniform enlargement by using.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the ethylene-methacrylic acid ester (or acrylic acid ester) copolymer It has been found that when the methacrylate (or acrylate) component content in the coalesced component has a specific ratio, the element gap at the time of stretching can be greatly and uniformly expanded, and the rubber-like elasticity is maintained. The present invention has been accomplished based on the findings.

That is, the present invention provides an adhesive tape for fixing a semiconductor wafer having a radiation-curable adhesive layer provided on one side of a substrate film, wherein the substrate film has an acrylic acid ester and / or methacrylic acid ester as a central layer. It has an ethylene-acrylate or methacrylate-based copolymer film layer with a content of 20 to 40% by weight, and an adhesive is applied to this layer via the adhesive layer or directly to the radiation-curable adhesive layer side The present invention provides an adhesive tape for fixing a semiconductor wafer, wherein the layer is a laminated film having a transfer prevention layer on the other side. In the present invention, radiation refers to ionizing radiation such as light rays such as ultraviolet rays or electron beams.

[0011] The ethylene-acrylate or methacrylate copolymer of the present invention (in the present specification, the term "(meth) acrylate" includes both methacrylate and acrylate).
As (meth) acrylate content 20wt%
Not less than 40% by weight of ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-ethyl 2-ethylhexyl acrylate copolymer, ethylene-glycidyl acrylate copolymer, ethylene-acrylic acid 2-hydroxyethyl acrylate copolymer, or a product obtained by replacing the above acrylic acid with methacrylic acid, or adding or substituting a low molecule such as maleic anhydride containing a functional group such as a carboxyl group to the above copolymer as required. Per se, such as modified denatured products,
Alternatively, a mixture or the like of these may be used, and the type and mixing ratio of the resin may be arbitrarily selected according to various conditions such as required characteristics of the base film and cost.

In the ethylene- (meth) acrylate-based copolymer of the present invention, the content of the (meth) acrylate is from 20% by weight to 40% by weight. this is,
If the content is less than 20% by weight, the rubber-like elasticity of the copolymer is weakened,
Necking tends to occur, making it impossible to stretch uniformly. As a result, the element gap is not widened, and
If the content exceeds wt%, the rubber elasticity is increased, but the tensile strength is reduced, and it is easy to break during stretching. Further, as the ethylene- (meth) acrylic acid copolymer, the ethylene-acrylic acid ester copolymer, and the ethylene-methacrylic acid ester copolymer become more difficult to break during stretching.

The ethylene- (meth) acrylate-based copolymer of the present invention is intended to enhance the compatibility in the blend composition described later and the interlayer adhesion in a multilayer structure or a laminated structure.
A monomer obtained by further copolymerizing a monomer such as acrylic acid, methacrylic acid, acrylonitrile, or vinyl acetate may be used. Further, for the central layer of the base film in the present invention, a blend resin composed of a composition obtained by blending another resin with an ethylene- (meth) acrylate-based copolymer can be used.

The resin which can be blended with the ethylene- (meth) acrylate-based copolymer of the present invention is ethylene- (meth) acrylate-based copolymer.
The resin is not particularly limited as long as it is compatible with the (meth) acrylate-based copolymer and has good radiation transmittance.

For example, low density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polymethylpentene, ethylene-acrylic acid copolymer, ionomer, ethylene-propylene Homopolymers such as diene copolymers, styrene-isoprene copolymers, styrene-butadiene copolymers, styrene-ethylene-butene copolymers, copolymers, etc., which are known per se, or mixtures thereof Or a mixture with another resin and an elastomer. The type of the resin and the blending ratio at 50 wt% or less can be arbitrarily selected according to the required characteristics of the base film, cost and other circumstances.

It is preferable to blend a resin having excellent adhesiveness with the pressure-sensitive adhesive coating layer and the transfer prevention layer, since delamination hardly occurs when the pressure-sensitive adhesive tape is stretched. As a mixing means for preparing the resin of the present invention, a heating roll, a Banbury mixer and the like are generally adopted. The use of the mixing means as described above makes mixing easy and reliable, so that the obtained base film also has the effect that there is no whitening phenomenon even when bent.

In the present invention, the ethylene- (meth) acrylate copolymer film serving as the center layer can be used as a multilayer film with a film made of another resin.

The film for forming the multilayer may be a conventionally known resin such as a resin compatible with the ethylene- (meth) acrylate copolymer, a resin which is hardly compatible but satisfies the requirement, or Or a mixture with other resins and elastomers, etc., and is arbitrarily selected according to various conditions such as required characteristics of the base film and cost. Further, the thickness of this film can be arbitrarily selected to be equal to or less than the thickness of the film made of the ethylene- (meth) acrylate copolymer.

In particular, when a multilayer film is formed using a film made of a resin having excellent adhesion to a (meth) acrylate-based copolymer, a pressure-sensitive adhesive applied layer or a transfer prevention layer, this is used as a central layer. The pressure-sensitive adhesive tape is preferable because it does not easily cause delamination when stretched.

As a method for producing the multilayer film, a conventionally known coextrusion method, laminating method, or the like is used. At this time, as is usually performed in the production of a normal laminated film, an adhesive between the multilayer films is used. May be applied. As such an adhesive, a conventionally known adhesive such as an ethylene-vinyl acetate copolymer or a maleic acid-modified ethylene-vinyl acetate copolymer can be used.

In the present invention, the resin for the pressure-sensitive adhesive coating layer on the side on which the radiation-curable pressure-sensitive adhesive is applied is a resin that is radiation-transmissive, does not easily contaminate the Si wafer, and has a large adhesive force with the radiation-curable pressure-sensitive adhesive. For example, preferably ethylene-based, low density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid copolymer, and conventionally known ones, Alternatively, a mixture of these and the like can be mentioned, and it can be arbitrarily selected depending on the adhesiveness to the radiation-curable pressure-sensitive adhesive to be used. This pressure-sensitive adhesive coating layer serves to strengthen the adhesion between the pressure-sensitive adhesive and the substrate film, and prevents contamination of the semiconductor wafer due to peeling of the pressure-sensitive adhesive from the substrate film when the pressure-sensitive adhesive tape is stretched after wafer processing. To contribute.

As the resin for the transfer prevention layer of the present invention, for example, ethylene resins are preferable, and low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methacrylic acid copolymer, Examples thereof include conventionally known ones such as an ethylene-acrylic acid copolymer, and mixtures thereof. This anti-transfer layer does not hinder the elongation characteristics of the pressure-sensitive adhesive tape and is intended to prevent blocking of the base film.

In order to reduce friction between the adhesive tape and the jig during stretching of the adhesive tape and prevent necking of the base film, a low-density polyethylene, an ethylene-vinyl acetate copolymer, and -The vinyl acetate copolymer is ethylene having a vinyl acetate content of 5 wt% or less.
It is preferable to use a vinyl acetate copolymer.

As a method for laminating the center layer and the pressure-sensitive adhesive applied layer or the transfer preventing layer, a known method such as a co-extrusion method, a heat fusion method or a lamination method using an adhesive is used. Examples of the adhesive in the case of laminating using an adhesive include an ethylene-vinyl acetate copolymer, a maleic acid-modified ethylene-vinyl acetate copolymer, a maleic acid-modified ethylene-α-olefin copolymer, a copolymerized polyester resin, and the like. Adhesive compounds, or mixtures thereof.

The ethylene-vinyl acetate copolymer used as the adhesive or the maleic acid-modified copolymer of this copolymer is preferably one having a vinyl acetate content of 20% by weight or more, since it has a large adhesive strength and hardly causes delamination.

The thickness of the base film is usually suitably from 30 to 300 μm from the viewpoints of strong elongation characteristics and radiation transparency. The thickness ratio of the center layer of the base film is arbitrarily set according to the required characteristics of the base film, but is usually preferably 30% or more with respect to the total thickness of the base film, and 50 to 90%.
% Is more preferred. Further, the thickness of the pressure-sensitive adhesive applied layer and the thickness of the transfer prevention layer are preferably substantially the same in order to prevent curling of the base film.

When the surface of the base material film on the side of the anti-transfer layer is textured or coated with a lubricant, blocking is prevented, and necking of the base film is prevented by reducing friction between the adhesive tape and the jig when the adhesive tape is stretched. This is preferable because it has the effect of

The radiation-curable pressure-sensitive adhesive is not particularly limited, and a normal pressure-sensitive adhesive can be used.
A linear polyester having 10 to 200 parts by weight of at least one compound selected from the group consisting of a cyanurate compound and a isocyanurate compound having a carbon-carbon double bond and two carbon-carbon double bonds with respect to 0 part by weight; Alternatively, when a pressure-sensitive adhesive containing 5 to 100 parts by weight of a polyol urethane acrylate compound is used, the rubber-like elasticity of the pressure-sensitive adhesive tape after irradiation can be maintained because the rubber-like elasticity of the pressure-sensitive adhesive layer after irradiation can be maintained. The effect of maintaining (flexibility) is particularly large.

When the adhesive tape for fixing a semiconductor wafer of the present invention is cured by ultraviolet irradiation, a photopolymerization initiator such as isopropylbenzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone is used. , Diethylthioxanthone, benzyl dimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethyl phenyl propane, etc. added to the pressure-sensitive adhesive layer allows the curing reaction to proceed efficiently even if the curing reaction time or the amount of ultraviolet irradiation is small, and the element is fixed. Adhesive strength can be reduced.

Further, if necessary, the surface of a radiation-curable silicon acrylate or silicon methacrylate or a semiconductor wafer as an adherend is coated with a metal substance in order to reduce the adhesive strength for fixing the element after irradiation with radiation. In order to similarly reduce the adhesive strength for fixing the element to the specially treated surface, an ion sequestering agent, etc., and a tackifier, an adhesion regulator, a surfactant, etc., or other modifiers and common components should be blended. Can be. The thickness of the radiation-curable pressure-sensitive adhesive layer is usually 2 to 50 μm.

[0031]

Next, the present invention will be described in more detail with reference to examples. In the following examples, each characteristic was tested and evaluated as follows.

1) Adhesive Force (g / 25 mm) The magnitude of the element-fixed adhesive force before irradiation and the degree of decrease after irradiation were examined. A 5-inch diameter Si wafer was used as an adherend on the radiation-curable pressure-sensitive adhesive tape thus prepared, and JIS-Z0
The adhesive force before and after ultraviolet irradiation was measured based on 237 (9).
0 ° peeling, peeling speed 50 mm / min). At this time, the surface state of the wafer bonded to the adhesive tape was a mirror surface state.

2) Element gap (μm) The size of the element gap and the degree of uniformity in the longitudinal / lateral directions when the adhesive tape was stretched were examined. A 5-inch diameter Si wafer fixed to the prepared radiation-curable adhesive tape is fully cut into two sizes of 3 × 3 mm and 6 × 6 mm using a dicing saw, and after ultraviolet curing, a wafer expanding device (air pressure 2) 0.0kg / cm) with an expanded stroke of 10mm
The vertical and horizontal device gap amounts when the film was raised and stretched were measured to determine the size and uniformity of the device gap. Here, the element gap amount includes a blade thickness of 40 μm at the time of dicing.

3) Strength of Expanded Adhesive Tape The state of the tape at an expand stroke of 30 mm was examined. Full cut into a size of 3 × 3 mm in the same manner as in the method 2), and the expand stroke is 30 mm.
The state of whether or not the pressure-sensitive adhesive tape when it was raised and stretched was broken was examined.

Examples 1 to 6 and Comparative Examples 1 to 4 The base films having the respective layers shown in Tables 1 and 2 were extruded by using an extruder to prepare the following resins A to G alone or a kneaded kneaded blend composition. By using (co) extrusion processing. The thickness of each of the obtained base films (consisting of the pressure-sensitive adhesive applied layer, the center layer, and the transfer prevention layer) is 100 μm. The obtained base film is subjected to a corona treatment on the side of the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer after drying has a thickness of 10 μm.
An adhesive was applied so as to obtain a radiation-curable adhesive tape.

The resins and pressure-sensitive adhesives used are shown below. Resin A (ethylene-methyl acrylate copolymer, methyl acrylate content: 20 wt%): Yucalon E manufactured by Mitsubishi Yuka
MA XG500M Resin B (ethylene-ethyl acrylate copolymer methyl acrylate content 25 wt%): Nippon Oil Co., Ltd. Nisseki Lexlon EEA A4250 Resin C (ethylene-ethyl methacrylate copolymer ethyl methacrylate content 38 wt% ): Sumitomo Chemical's ACLIFT CM4011 Resin D (ethylene-ethyl methacrylate copolymer ethyl acrylate content 10 wt%): Sumitomo Chemical's ACLIFT WD201 resin E (ethylene-ethyl acrylate copolymer ethyl acrylate content 41 wt%) %): NUC manufactured by Nippon Unicar
Copolymer EEA MB-870 Resin F (ethylene-methacrylic acid copolymer, methacrylic acid content 20 wt%): Dow Chemical Primacol 5980 Resin G (1,2-polybutadiene): Japan Synthetic Rubber
RB805 EPR (ethylene-propylene-diene copolymer): EP 51 EVA-10 (ethylene-vinyl acetate copolymer (vinyl acetate content: 10 wt%) manufactured by Nippon Synthetic Rubber): Evatate H manufactured by Sumitomo Chemical Co., Ltd.
2021F EVA-3 (ethylene-vinyl acetate copolymer (vinyl acetate content: 3 wt%)): Yucalon-Eva V1 manufactured by Mitsubishi Yuka
13K LLDPE (low-density polyethylene): Petrocene 205 manufactured by Tosoh Co., Ltd. A: Acrylic adhesive 100 parts by weight Isocyanurate compound 80 parts by weight Urethane acrylate compound 20 parts by weight Photopolymerization initiator 1 part by weight Adhesive B: Acrylic adhesive 100 parts by weight Cyanurate compound 40 parts by weight Urethane acrylate compound 10 parts by weight

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

When the adhesive tape for fixing a semiconductor of the present invention is used for cutting semiconductor wafers or the like, the adhesive tape maintains rubber-like elasticity (flexibility) even after irradiation, and has excellent stretchability. Since breakage due to deterioration of the base film due to irradiation does not occur, the gap between the elements can be greatly and uniformly enlarged by the adhesive tape, so that the image recognition of the element pieces becomes easy. Therefore, there is an excellent effect that the element can be picked up easily and without damage.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Ishiwatari 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Kazushige Iwamoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Morikuni Hasebe 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (58) Fields investigated (Int. Cl. ⁶ , DB name) C09J 7 / 02 H01L 21/301 WPI / L (QUESTEL)

Claims (1)

(57) [Claims] In a pressure-sensitive adhesive tape for fixing a semiconductor wafer having a radiation-curable pressure-sensitive adhesive layer provided on one side of a substrate film, the substrate film has an acrylic ester and / or methacrylic ester content of 20 as a central layer. ~ 40
It has a wt.% ethylene-acrylate or methacrylate-based copolymer film layer, and an adhesive coating layer on the radiation-curable pressure-sensitive adhesive layer side via an adhesive layer or directly on this layer, and An adhesive tape for fixing a semiconductor wafer, which is a laminated film having a transfer prevention layer on the side.