JP2003261838A - Adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive tape which has an adhesive strength sufficient for preventing a wafer and a substrate film from peeling off from an adhesive layer upon dicing, allows adhesion of the rear surface of a chip to the adhesive layer through radiation curing and therefore allows separation of the chip from the substrate film at pick-up, and enables so-called direct die bonding wherein a sufficient adhesive strength between the chip and a lead frame, etc., can be achieved in a mounting step. <P>SOLUTION: The adhesive tape is one for semiconductor wafer dicing and die bonding which is prepared by establishing the adhesive layer on at least one side of the substrate film. The adhesive is an acrylic adhesive having a gel percentage of ≥60%. The adhesive has a resin component having at least a group containing a radiation-curable carbon-carbon double bond, an epoxy- containing group and a carboxyl group-containing group. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer provided on one surface of a base film and a normal separator provided on the pressure-sensitive adhesive layer side. More specifically, when manufacturing a semiconductor device such as a silicon wafer, the wafer is fixed, the wafer is diced, and the semiconductor wafer dicing is used in a bonding process for stacking with a lead frame or a semiconductor chip-a viscous adhesive tape for die bonding. It is about.

[0002]

2. Description of the Related Art In the process of assembling a semiconductor device such as an IC, a semiconductor wafer after pattern formation is cut into individual chips (dicing), chips are mounted on a lead frame, and resin is used. The process consists of sealing with. The dicing process is a process in which a semiconductor wafer is attached to an adhesive tape in advance and fixed, and then the dicing is performed along the chip shape. The mounting process peels (picks up) the chip from the adhesive tape and seals it with resin or the like. In the step, the chip is fixed to a lead frame or the like with an adhesive for fixing the chip.

As the tape used for the above purpose, there are an ordinary pressure-sensitive adhesive type tape and a tape having a property of being hardened by radiation such as ultraviolet rays and electron beams to lower the adhesive strength. A sufficient adhesive force is required to prevent the wafer from peeling off, and a property of easily peeling off at the time of pickup is required. Further, in the mounting step, a sufficient adhesive force is required between the chip and the lead frame.

[0004]

The adhesive tape for dicing used in the above steps and the function of the adhesive to the lead frame and the like are combined to improve the workability of applying the adhesive and to simplify the process. Various adhesive tapes have been proposed (for example, JP-A-2-32181 and JP-A-8-53).
655, etc.). The adhesive tape disclosed in the above publication enables so-called direct die bonding, in which after dicing, the chip back surface is picked up with the adhesive layer still attached, mounted on a lead frame or the like, and then cured and adhered by heating or the like. This makes it possible to omit the coating step. However, JP-A-2-3
The adhesive / adhesive disclosed in No. 2181 generally has a low viscosity when dried at high temperature, and the tape substrate has a low surface energy of 40 dyne / cm. The wettability is low, repellency is likely to occur even when applied to a substrate, and the yield is low. Furthermore, so-called transfer coating, in which the above-mentioned coating liquid is applied to a release material treated with a silicone release agent, dried, and laminated on a tape base material, is more difficult with the coating liquid of the composition (Japanese Patent Laid-Open No. Hei 8). -53655). In addition, JP-A-2-32181 and JP-A-8-5
No. 3655 discloses a pressure-sensitive adhesive containing an epoxy resin and a heat-activatable latent epoxy resin curing agent. Since this curing agent is hygroscopic, the curing is accelerated by moisture and the pot life is reduced. Therefore, there was a problem that storage stability was poor.

[0005]

Means for Solving the Problems As a result of extensive studies to achieve the above-mentioned object, as a tacky-adhesive composition used for the above-mentioned tacky-adhesive tape, at least a carbon chain of a main chain has a radiation group as a bonding group. When an acrylic pressure-sensitive adhesive composition having a curable carbon-carbon double bond-containing group, an epoxy group-containing group, and a carboxyl group-containing group is used, it is adhered by a crosslinking reaction due to the carbon-carbon double bond when irradiated with radiation. It was found that the curing of the curing agent and the subsequent addition of heat causes a crosslinking reaction between the epoxy group and the carboxyl group to further cure, and a thermosetting resin and a heat-activable latent epoxy resin curing agent were added. Without doing so, a pressure-sensitive adhesive tape having radiation curing and thermosetting properties was developed, and a pressure-sensitive adhesive tape having a long pot life and excellent storage stability was invented. The present invention relates to a tacky adhesive tape having excellent storage stability capable of exhibiting a two-step curing reaction of radiation curing and heat curing without adding a thermosetting resin and a heat-activatable latent epoxy resin curing agent. It is a thing. More specifically, it has sufficient adhesive strength that the adhesive layer does not peel off from the wafer and base film during dicing, and when picked up, the back surface of the chip is adhered to the adhesive layer by radiation curing and peeled off from the base film. This is suitable for enabling so-called direct die bonding in which a sufficient adhesive force can be obtained between the chip and the lead frame in the mounting step. That is, the present invention relates to (1) a pressure-sensitive adhesive tape for semiconductor wafer dicing-die-bonding, comprising a base material film having an adhesive layer on at least one surface thereof, wherein the resin component of the adhesive is at least radiation curable carbon-carbon dicarbonate. An adhesive pressure-sensitive adhesive tape comprising an acrylic pressure-sensitive adhesive having a heavy bond-containing group, an epoxy group-containing group, and a carboxyl group-containing group, and having a gel fraction of 60% or more, (2) (A)
(Meth) acrylic acid ester, (b) epoxy group-containing unsaturated compound and (c) acrylic copolymer having carbon-carbon double bond, (d) (meth) acrylic acid ester, (e) carboxyl group A pressure-sensitive adhesive tape characterized by being a mixture of a containing unsaturated compound and (f) an acrylic copolymer having a carbon-carbon double bond, or a crosslinked product thereof, and (3) an acrylic copolymer The ratio of constituents having an epoxy group-containing group in all constituents is 5
˜20 mol%, the proportion of the constituent component having a carboxyl group-containing group is 5 to 20 mol%, and the proportion of the constituent component having a carbon-carbon double bond-containing group is 1 to 10 mol%. (1) or The tacky adhesive tape according to item (2) is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive used in the present invention is
At least carbon-radiation curable carbon-carbon double bond-containing group in the main chain consisting of carbon bonds, and an epoxy group-containing group, and an acrylic copolymer having a carboxyl group-containing group or a mixture of acrylic copolymers or It is composed of a cross-linked product. Such an acrylic copolymer is a copolymer (A) composed of a (meth) acrylic acid ester, a hydroxyl group-containing unsaturated compound, a carboxyl group-containing unsaturated compound, an epoxy group-containing unsaturated compound, etc. A compound having a functional group capable of undergoing an addition reaction with a functional group of a copolymer and a carbon-carbon double bond (B)
Can be obtained by addition reaction. The unsaturated compound in the present invention means at least one carbon-carbon double bond which can be cured by radiation.
A compound having two

Examples of the above-mentioned (meth) acrylic acid ester include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate and the like. Further, examples of the hydroxyl group-containing unsaturated compound include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and the like. Examples of the carboxyl group-containing unsaturated compound include acrylic acid and methacrylic acid. As the epoxy group-containing unsaturated compound,
Glycidyl acrylate, glycidyl methacrylate,
Allyl glycidyl ether etc. are mentioned. As the compound (B) having a functional group capable of undergoing an addition reaction and a carbon-carbon double bond, for example, an isocyanate compound such as 2-isocyanate ethyl methacrylate capable of reacting with a hydroxyl group, a compound capable of reacting with an epoxy group Examples thereof include acrylic acid having a carboxyl group, methacrylic acid, and an epoxy group-containing unsaturated compound capable of reacting with a carboxyl group.

In the production of the copolymer, in addition to the unsaturated compound having an epoxy group-containing group, a carboxyl group-containing group and a hydroxyl group-containing group, one kind or a combination of two or more kinds of (meth) acrylic acid ester is used. Can be used. The method of synthesizing the acrylic copolymer includes (1) a copolymer composed of (meth) acrylic acid ester, a hydroxyl group-containing unsaturated compound, a carboxyl group-containing unsaturated compound, an epoxy group-containing unsaturated compound, and the like ( A method of adding to (A) a compound (B) having a functional group capable of addition-reacting with a functional group of these copolymers and a carbon-carbon double bond, (2) containing no epoxy group A copolymer (A-1) consisting of a saturated compound, a hydroxyl group-containing unsaturated compound, and a (meth) acrylic acid ester, and a carboxyl group-containing unsaturated compound, a hydroxyl group-containing unsaturated compound, and a (meth) acrylic acid ester The copolymer (A-2) and the above copolymer (A-1)
A compound (B) having a functional group capable of reacting with either an epoxy group, a carboxyl group or a hydroxyl group having a carbon-carbon double bond is added to (A-2), and then both are mixed. It can be synthesized by any method, and the same effect can be obtained by any method. Further, the acrylic copolymer, when the concentration of the epoxy group or the carboxyl group is high, the epoxy group and the carboxyl group are likely to react during the polymerization, for example, an epoxy group-containing unsaturated compound, a hydroxyl group-containing unsaturated compound A copolymer (A-1) composed of a (meth) acrylic acid ester, and a carboxyl group-containing unsaturated compound, a hydroxyl group-containing unsaturated compound, a copolymer (A-2) composed of a (meth) acrylic acid ester Are separately copolymerized, and a compound (B) having a functional group capable of reacting with a hydroxyl group having a carbon-carbon double bond is added to each of the above copolymers (A-1) and (A-2). After the reaction, it is preferably prepared by mixing both.

The weight average molecular weight of the acrylic copolymer used in the present invention is preferably 10,000 to 100.
10,000, more preferably 50,000 to 500,000. The ratio of the constituent having a carbon-carbon double bond-containing group in all constituents (repeating units) of the acrylic polymer of the present invention is preferably 1 to 20 mol%, more preferably 1 to 10 mol%. . If the ratio of the carbon-carbon double bond-containing group is too low, the degree of crosslinking upon irradiation with radiation will be insufficient, so that the adhesive layer and the base film layer cannot be easily separated in the pickup step. However, if the proportion is too high, the degree of crosslinking at the time of irradiation with radiation becomes too high, and the subsequent heat curing may not proceed sufficiently.

The ratio of the constituent having an epoxy group-containing group to the total constituents of the acrylic copolymer is preferably 1 to 30 mol%, more preferably 5 to 20 mol%. The proportion of the constituent having a carboxyl group-containing group is preferably 1 to 30 mol%, more preferably 5 to 20 mol%. If the ratio of the epoxy group and the carboxyl group is too low, the degree of crosslinking at the time of heating will be insufficient, so that sufficient adhesive force between the chip and the lead frame or the like may not be obtained in the mounting step. If the ratio of both is too high,
A sufficient adhesive force for fixing the wafer during dicing cannot be obtained. The acrylic copolymer thus obtained is
If necessary, a crosslinking agent such as a polyisocyanate compound, an alkyl etherified melamine compound or an alkyl etherified melamine compound can be added. The amount of the crosslinking agent added is preferably 0.01 to 5.0 parts by weight with respect to 100 parts by weight of the acrylic copolymer.

When the radiation-curable pressure-sensitive adhesive of the present invention is cured by irradiation with ultraviolet rays, a photopolymerization initiator such as isopropyl benzoin ether may be added, if necessary.
It is possible to use isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, benzyldimethylketal, α-hydroxycyclohexylphenyl ketone, 2-hydroxymethylphenylpropane and the like. The blending amount of these photopolymerization initiators is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic copolymer. In the present invention, the gel fraction of this pressure-sensitive adhesive is determined as follows, for example. That is, about 0.05 g of the adhesive layer of the adhesive tape was weighed, immersed in 50 ml of xylene at 120 ° C. for 24 hours, and then filtered through a 200-mesh stainless wire net to remove insoluble matter on the wire net at 110 ° C. Dry for 120 minutes. Next, the weight of the dried insoluble matter is weighed, and the gel fraction is calculated by the formula shown below. Gel fraction (%) = (weight of insoluble matter / weight of weighed pressure-sensitive adhesive layer) × 100 In the present invention, when a low-molecular component is present in the pressure-sensitive adhesive, it is stored for a long time after tape production. Since the low-molecular component may migrate to the tape surface during the heating and impair the visco-adhesive properties, it is desirable that the gel fraction is high, usually 60% or more, preferably 70% or more.

Further, it is possible to add fine metal powders or other materials having excellent electrical conductivity or thermal conductivity to the above adhesive for the purpose of imparting electrical conductivity and thermal conductivity after die bonding. . In addition, it is possible to add fine powders of metal oxides, glass, etc. to the adhesive / bonding agent for the purpose of improving thermal stability. The thickness of the adhesive coating layer is 5 to 5
0 μm is preferred.

As the base film used in the present invention, known films can be used as long as they have a radiation transmitting property, and examples thereof include polyethylene, polypropylene, ethylene-propylene copolymer, polybutene and ethylene-. Vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, homopolymers or copolymers of α-olefins such as ionomers, polyethylene terephthalate, polycarbonate, engineering plastics such as polymethylmethacrylate, or polyurethane, styrene-ethylene -A thermoplastic elastomer such as butene or pentene copolymer is used. Alternatively, it may be a mixture of two or more kinds selected from these groups or a multilayer structure. Film thickness is 50-20
0 μm is preferably used. Before use, the pressure-sensitive adhesive tape of the present invention has a separator (release film) attached to the pressure-sensitive adhesive layer side for protection.

The adhesive tape thus obtained is
It has sufficient adhesive strength to prevent peeling of the adhesive layer from the wafer and base film during dicing, and can be peeled from the base film with the adhesive layer and the back surface of the chip adhered to each other by radiation curing during picking up and heating. Can be bonded to a lead frame or the like. The peeling force (force required for peeling) between the silicon wafer and the adhesive tape at the time of dicing is preferably 0.5 to 10 N / 25 mm, more preferably 1 to 5 N / 25 mm, and the silicon wafer after radiation irradiation. The peeling force of adhesive tape is 0.5 to 50
N / 25 mm, and the peeling force between the base film and the pressure-sensitive adhesive layer of the adhesive tape is preferably 0.5 N / mm or less. In this case, of course, the relationship of the peeling force requires that the former be larger than the latter. Then, in the mounting process,
By heating, the curing reaction of the epoxy group and the carboxyl group in the adhesive layer realizes the adhesion between the IC chip and the lead frame or the IC chip and the IC chip. The heating temperature in this case is not particularly limited, but is usually preferably 100 to 200 ° C., and the heating time is
1 to 60 minutes is preferable.

[0015]

EXAMPLES Next, the present invention will be described in more detail based on examples. In addition, each characteristic in the following implementations was tested as follows.

1. Gel fraction: About 0.05 g of the pressure-sensitive adhesive layer was weighed and immersed in 50 ml of xylene at 120 ° C. for 24 hours, and then filtered through a 200-mesh stainless steel wire net, and the insoluble content on the wire net was kept at 110 ° C. at 120 ° C. Dry for minutes. Next, the weight of the dried insoluble matter was weighed, and the gel fraction was calculated by the formula shown below. Gel fraction (%) = (weight of insoluble matter / weight of weighed adhesive layer) × 100

2. Storage stability The adhesive and pressure-sensitive adhesive tapes prepared on the basis of Examples and Comparative Examples were left in an environment of 60 ° C. and 85% RH for 1 week, left at room temperature for 1 hour, and then adhered to an adherend. The storage stability was evaluated by measuring the peeling force of a pressure-sensitive adhesive tape which was not heat-treated and adhered to an adherend, and confirming the change rate of the peeling force. As a measuring method of the peeling force, JIS Z 0
237. (The tape was cut into a width of 25 mm and a length of about 250 mm, and the surface of SUS 304 steel plate was polished with No. 280 water-resistant abrasive paper.
9 pressed with a rubber roller weighing 2000 g
Measured by the 0-degree peeling method. ) Rate of change (%) = (Adhesive force difference before and after heating / peeling force before heating and leaving) x 100, and peeling force change rate before and after standing is less than 30%: ○ Peeling force change rate before and after standing 30% or more: judged by x.

3. Dicing property evaluation (confirmation of chip fly) A wafer was bonded to the adhesive tape prepared based on the examples and comparative examples under the following conditions, and it was confirmed whether chips were scattered during dicing. No chip fly: ○ Only chip with incompletely shaped chip on the wafer outer periphery: △ Chip fly: Judged.

4. Shear adhesive strength Examples, the wafer was bonded to the adhesive tape prepared based on the comparative example under the following conditions, after diced and irradiated with ultraviolet rays, peeled from the high-density polyethylene resin film layer,
After sticking to a silicon wafer and applying a load of 39.2 kPa and holding at 150 ° C. for 30 minutes to cure the adhesive layer,
Normal temperature (23 ℃) and 200 ℃ using push-pull gauge
The shear adhesive strength was measured.

3. And 4. The dicing conditions for
The following conditions were set. Dicing device: Disco DAD-340 blade: Disco NBC-ZH2050 27HEDD blade rotation speed: 40000 rpm Cutting speed: 100 mm / sec Uncut thickness: 50 μm Dicing size: 5 mm square wafer: Si wafer Wafer size: 6 inches Wafer thickness : 350 μm Wafer backside surface roughness: # 2000 Polished surface

Synthesis of Copolymer A Copolymer A was prepared by using butyl acrylate, 2-hydroxyethyl acrylate and acrylic acid as raw materials and the following Table 1
Polymerization was performed at a compounding ratio of to obtain a copolymer. 2 in this polymer
-Isocyanate ethyl methacrylate was subjected to an addition reaction at a compounding ratio shown in Table 1 below to obtain a copolymer A.

[0022]

[Table 1]

Synthesis of Copolymer B Copolymer B was obtained by polymerizing butyl acrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate as raw materials at the compounding ratio shown in Table 2 below.
2-Isocyanate ethyl methacrylate was added to this polymer at the compounding ratio shown in Table 2 below to obtain a copolymer B.

[0024]

[Table 2]

Preparation of tacky adhesive tape Copolymers A and B obtained by synthesizing copolymer A and copolymer B, and a polyisocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a curing agent, Α-Hydroxycyclohexyl phenyl ketone as a photoinitiator was mixed in the compounding ratio shown in Table C below to obtain an adhesive. The thickness of each adhesive after drying was set to 30 μm, and each was applied to a high-density polyethylene resin film (100 μm) to prepare an adhesive tape. As a result, the copolymers A and B undergo a curing reaction by the reaction between the hydroxyl groups of the copolymers A and B and the isocyanate group functional group of the curing agent in the heating and drying step, and the copolymers A and B are contained. In addition to the photo-curing reaction of the carbon-carbon double bond, the carboxyl group of the copolymer A and the epoxy group of the copolymer B can cause a curing reaction by heating.

[0026]

[Table 3]

[0027]

[Table 4]

As Comparative Example 1, bisphenol-based glycidyl type epoxy resin (Epicoat 828, Epicoat 1
002 (manufactured by Japan Epoxy Resin Co., Ltd.) and 300 parts by weight each, and 18 parts by weight of a heat-activable latent epoxy resin curing agent (San-Aid SI-100L (trade name) manufactured by Sanshin Chemical Industry Co., Ltd.).

[0029]

[Table 5]

[0030]

[Table 6]

[0031]

As described above, according to the present invention, it is possible to provide a tacky adhesive tape which can be used as a dicing tape during dicing, can be used as an adhesive during mounting, and has good storage stability. You can

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J004 AA01 AA02 AA10 AA13 CA03                       CA04 CA06 CC02 FA05 FA08                 4J040 DF031 DF032 EC221 EC222                       FA142 GA01 GA05 GA07                       JB07 KA16 MA04 MA10 NA20                 5F047 BA22 BA33 BA34 BB03 BB19

Claims (3)

[Claims] 1. A pressure-sensitive adhesive tape for semiconductor wafer dicing-die bonding, comprising a substrate film having an adhesive layer on at least one surface thereof, wherein the resin component of the adhesive contains at least a radiation-curable carbon-carbon double bond. An acrylic pressure-sensitive adhesive having a group, an epoxy group-containing group, and a carboxyl group-containing group, and having a gel fraction of 60%
The adhesive tape characterized by the above. 2. (a) (meth) acrylic acid ester,
(B) Epoxy group-containing unsaturated compound and (c) carbon-
An acrylic copolymer having a carbon double bond, (d)
Adhesive adhesion characterized by being a mixture of (meth) acrylic acid ester, (e) carboxyl group-containing unsaturated compound and (f) acrylic copolymer having a carbon-carbon double bond, or a crosslinked product thereof. tape. 3. The proportion of the constituent having an epoxy group-containing group in all constituents in the acrylic copolymer is 5 to 20 mol.
%, The ratio of constituents having a carboxyl group-containing group is 5
The adhesive tape according to claim 1 or 2, wherein the content of the component having a carbon-carbon double bond-containing group is 1 to 10 mol%.