JP3008623B2 - 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 an adhesive tape for fixing a semiconductor wafer comprising a base film that transmits ionizing radiation such as an electron beam, and an adhesive layer having a property of being cured by irradiation of radiation applied to the base film. In detail, this adhesive tape is adhered to the semiconductor wafer and the element fixing adhesive strength is kept strong during the dicing process, and after the semiconductor wafer is cut and separated into small pieces, radiation is applied from the base film side to the radiation-curable adhesive layer. By hardening the element fixing adhesive force is greatly reduced, regardless of the size of the element piece, for example, 25 mm
^This is a system in which even large elements of ^two or more can be easily picked up. 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 tackiness.

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, those using flexible polyvinyl chloride (PVC) as a central layer of a substrate film have 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 x 3 mm, stretching before irradiation can expand the element enough to prevent contact between elements in the element gap, but after irradiation, In order to obtain a large and uniform gap of the element pieces required for the pickup device with image recognition even in the stretching of the film, characteristics such as breakage due to deterioration of the base film due to radiation irradiation during stretching after irradiation Was inadequate.

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, based on a laminated film having a central layer of styrene-ethylene-butene-styrene copolymer (SEBS) Adhesive tapes as material films have been proposed. However, in these adhesive tapes, 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 with radiation, the base film itself must be formed. There were insufficient properties such as necking (partial elongation due to poor force propagation during film stretching) and loss of rubbery elasticity due to deterioration of the base film due to irradiation.

[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. In other words, in the present invention, the material of the center layer of the base film is carefully studied, and the adhesive tape after irradiation is maintained in a rubber-like elasticity (flexibility), and at the same time, is not broken due to deterioration of the base film due to irradiation. Another object of the present invention is to provide an adhesive tape for fixing a semiconductor wafer, in which the gap between the elements can be largely and uniformly enlarged by stretching the adhesive tape after irradiation with radiation, and there is no breakage due to heat during pickup.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that the ethylene-methacrylic acid copolymer has a zinc layer as the central layer of the base film. Those having an ionomer resin cross-linked with ions, enable a large and uniform expansion of the element gap by stretching the adhesive tape after irradiation, and found that the base film did not break due to the heat of the die bonder used during pickup. The present invention has been accomplished based on this finding.

That is, the present invention relates to 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 ethylene-methacrylic acid copolymer molecule as a central layer. A lamination having an ionomer resin film layer cross-linked with zinc ions, with an adhesive coating layer on this layer or directly on the radiation-curable pressure-sensitive adhesive layer side and a transfer prevention layer on the other side An object of the present invention is to provide an adhesive tape for fixing a semiconductor wafer, which is a film. In the present invention, the term “radiation” refers to light such as ultraviolet light or ionizing radiation such as an electron beam.

As the ionomer resin in the present invention, an ethylene-methacrylic acid copolymer obtained by cross-linking the molecules of the copolymer with zinc ions, and maleic anhydride containing a functional group such as a carboxyl group, if necessary, may be added to the copolymer. Conventionally known modified products such as modified or modified by adding or substituting a low molecule such as an acid, or mixtures thereof are used. Depending on circumstances such as the required properties of the base film and cost, the type and mixing ratio of the resin are selected. Can be arbitrarily selected.

In the ionomer resin of the present invention, in which the intermolecular cross-linking of the ethylene-methacrylic acid copolymer is carried out with zinc ions, the reason why the metal cross-linking between the molecules is limited to zinc is that the characteristics of the wafer (mainly the electric characteristics) Because it does not adversely affect Incidentally, the ionomer resin obtained by crosslinking the molecules of the ethylene-methacrylic acid copolymer of the present invention with zinc ions is compatible with a blend composition described below,
In order to increase the interlayer adhesive strength in a multilayer structure or a laminated structure, a monomer such as acrylic acid, acrylonitrile, vinyl acetate or the like may be further copolymerized.

In the present invention, the center layer of the base film may be a blend resin made of a composition obtained by blending another resin with an ionomer resin. The resin that can be blended with the ionomer resin in which the molecules of the ethylene-methacrylic acid copolymer of the present invention are crosslinked with zinc ions is compatible with the ionomer resin in which the molecules of the ethylene-methacrylic acid copolymer are crosslinked with zinc ions. The resin is not particularly limited as long as it is soluble 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, ethylene-
Methacrylic acid copolymer, ethylene-acrylate copolymer, ethylene-methacrylate copolymer, ethylene-propylene-diene copolymer, styrene-isoprene copolymer, styrene-butadiene copolymer,
Homopolymers such as styrene-ethylene-butene copolymers, conventionally known copolymers such as copolymers or mixtures thereof, or mixtures with other resins and elastomers, and the like, required characteristics of the base film, cost, etc. The type of resin and the blend ratio can be arbitrarily selected according to various circumstances. In addition, when the pressure-sensitive adhesive tape is stretched by blending a resin having excellent adhesiveness with the pressure-sensitive adhesive coating layer and the transfer prevention layer,
This is preferable because delamination hardly occurs.

As a mixing means for preparing the resin of the present invention, a heating roll, a Banbury mixer and the like are generally employed. 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, a multilayer film of an ionomer resin film serving as a center layer and a film made of another resin can be used as the center layer. The film for forming the multilayer is, for example, a resin having compatibility, a resin that is hardly compatible but satisfies the requirement, and a conventionally known material such as a mixture thereof, or the like. It is arbitrarily selected according to various circumstances such as.
In addition, the thickness of this film can be arbitrarily selected below the thickness of the film made of the ionomer resin, in particular, the ionomer resin, using a film made of a resin having excellent adhesion with the pressure-sensitive adhesive coating layer or the transfer prevention layer. When a multi-layer film is used, the pressure-sensitive adhesive tape using this as a center layer is preferable because it does not easily cause delamination when stretched.

As a method for producing the multilayer film, a conventionally known co-extrusion method, lamination method, or the like is used. At this time, an adhesive between the multilayer films is used, as is usually performed in the production of a normal laminated film. May be interposed. 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-transparent, hardly contaminates 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 plays a role to strengthen the adhesion between the pressure-sensitive adhesive and the base film,
It contributes to prevention of contamination of the semiconductor wafer due to peeling of the adhesive from the base film when the adhesive tape is stretched after wafer processing.

As the resin for the anti-transfer layer of the present invention, for example, an ethylene resin is 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 is for preventing blocking of the base film without hindering the elongation characteristics of the pressure-sensitive adhesive tape.

In order to reduce friction between the pressure-sensitive adhesive tape and the jig when the pressure-sensitive adhesive tape is stretched and to prevent necking of the base film, a low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene It is preferable to use an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5% by weight or less as the vinyl acetate copolymer.

As a method for laminating the center layer and the pressure-sensitive adhesive coating layer or the transfer prevention layer, a conventionally known method such as a co-extrusion method, heat fusion or lamination method with 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. still,
The ethylene-vinyl acetate copolymer used as an adhesive or the maleic acid-modified copolymer of this copolymer is preferably one having a vinyl acetate content of 20% or more because it has a large adhesive strength and hardly causes delamination.

The thickness of the substrate film is usually preferably 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.
% Is more preferred. The thickness of the pressure-sensitive adhesive coating 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 transfer prevention layer side surface of the base film is embossed or coated with a lubricant, effects such as blocking prevention and necking of the base film by reducing friction between the adhesive tape and the jig when the adhesive tape is stretched are reduced. Is preferred.

As the radiation-curable pressure-sensitive adhesive, a normal pressure-sensitive adhesive is used without any particular limitation.
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 isopropyl benzoin 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.

If necessary, a radiation-curable silicon acrylate or silicon methacrylate or a semiconductor wafer as an adherend is coated with a metal substance in order to satisfactorily reduce the adhesive strength for fixing the element after irradiation. 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, a viscosity modifier, 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.

[0026]

Next, the present invention will be described in more detail with reference to examples. Examples 1 to 5 and Comparative Examples 1 and 2 The base films having the respective layer constitutions shown in Tables 1 and 2 were coexisted using an extruder using the following resins A to C alone or a kneaded kneading blend composition. It was prepared by extrusion.
All of the obtained base films have a thickness of 100 μm. The obtained base film was subjected to a corona treatment on the side of the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive was applied so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, to prepare a radiation-curable pressure-sensitive adhesive tape.

The resins and adhesives used are shown below. Resin A (zinc ion crosslinked ethylene- methacrylic acid copolymer): Himilan 1705, manufactured by Du Pont-Mitsui Polychemicals Resin B (ethylene-methacrylic acid copolymer): Nucrel 410 resin C, manufactured by DuPont-Mitsui Poly (1,2 polybutadiene ): RB805 SEB (styrene-ethylene-butene copolymer) manufactured by Nippon Synthetic Rubber: KRATON G1650 EVA-10 (ethylene-vinyl acetate copolymer (vinyl acetate content 10%)) manufactured by Shell Chemical: Evatate manufactured by Sumitomo Chemical Co., Ltd. H2021F EVA-3 (Ethylene-vinyl acetate copolymer (vinyl acetate content: 3%)): Yucalon-Eva V113K LLDPE (low-density polyethylene) manufactured by Mitsubishi Yuka: Petrocene 205 manufactured by Tosoh

Adhesive 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

The properties of the obtained pressure-sensitive adhesive tape were evaluated by the following methods, and are shown in Tables 1 and 2. The evaluation method of each characteristic is as follows.

1) Adhesive Strength (g / 25 mm) The magnitude of the adhesive strength for fixing the element 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 vertical and horizontal directions when the adhesive tape was stretched were examined. A 5-inch diameter Si wafer fixed to the radiation-curable pressure-sensitive adhesive tape was fully cut into two sizes, 3 × 3 mm and 6 × 6 mm, using a dicing saw. After ultraviolet curing, the wafer expansion device (air pressure 2.0
kg / cm 2), the device gap in the vertical and horizontal directions when the film was stretched by increasing the expand stroke by 10 mm was measured, and the size and uniformity of the device gap were observed. Here, the element gap amount includes a blade thickness of 40 μm at the time of dicing.

3) Strength of Expanding Adhesive Tape The state of the tape at an expanding stroke of 30 mm was examined. In the same manner as in 2), full cut was performed to a size of 3 × 3 mm, and the state of whether the adhesive tape was broken when stretched by increasing the expand stroke by 30 mm was examined.

4) Strength of adhesive tape during pickup The state of the tape during element pickup was examined. After full-cutting to a size of 3 × 3 mm in the same manner as in 2) and stretching the film by increasing the expand stroke by 30 mm, it was checked whether or not the adhesive tape when the element was picked up was broken.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

When the adhesive tape for fixing a semiconductor of the present invention is used for cutting semiconductor wafers and the like, the adhesive tape after irradiation maintains rubber-like elasticity (flexibility) 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. Also, breakage due to heat during pickup does not occur. Therefore, there is an excellent effect that the element can be picked up easily and without damage.

Continuation of the front page (72) Inventor Kazushige Iwamoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Examiner, Furukawa Electric Co., Ltd. Osamu Sato (56) References JP-A-5-98220 (JP, A) JP-A-63-17980 (JP, A) JP-A-3-121167 (JP, A) JP-A-62-141085 (JP, A) JP-A-49-118779 (JP, A) (58) Int.Cl. ⁷ , DB name) C09J 7/02 H01L 21/301 H01L 21/68

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 serves as a central layer between ethylene-methacrylic acid copolymer molecules. It has an ionomer resin film layer cross-linked with zinc ions, through an adhesive layer to this layer, or directly, a laminated film having a pressure-sensitive adhesive coating layer on the radiation-curable pressure-sensitive adhesive layer side and a transfer prevention layer on the other side. An adhesive tape for fixing a semiconductor wafer.