JP2001019912A - Die attach paste and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a die attach paste excellent in adhesivehess rapidly curing property and reliability and useful for producing semiconductor devices by including two kinds of specific diacrylates etc., a specific phosphate-group- containing acrylate, etc., a specific alkoxysilane and an organic peroxide, etc. SOLUTION: This paste is prepared by including (A) an ethylene oxide isocyanuric acid-modified diacrylate or triacrylate of formula I (wherein A is CH2=CHCO or H), (B) a di(meth)acrylate of formula II (wherein R1 is CH3 or H; R2 is a >=10C substituent including alicyclic group and/or aromatic group), (C) a phosphate-groupcontaining acrylate of formula III [wherein (a) is 0 or 1; and (b) is 1 or 2, (c) is 1 or 2 and (b)+(c)=3] and/or a phosphate- groupcontaining methacrylate of formula IV, (D) an alkoxysilane having alicyclic epoxy group, (E) an organic peroxide and/or an azo compound, and (F) inorganic filler. The weight ratio of the ingredient A to the ingredient B preferably is (80/20) to (20/80).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor bonding paste which is excellent in adhesiveness, rapid curing property and reliability.

[0002]

2. Description of the Related Art In recent years, the production volume of semiconductor packages has been on an increasing trend, and accordingly, reduction of manufacturing costs has become an important issue. In the process of assembling a semiconductor package, there is a process of bonding a semiconductor and a lead frame with a die attach paste. In this process, time reduction and low-temperature curing are key points. The curing process is roughly classified into a batch-type oven method and an in-line curing method, and a normal die mount using a fast-curing paste used in-line is typically used at 150 ° C. to 200 ° C. for 30 minutes.
It takes place between seconds and 60 seconds. However, development of a paste that can be cured at a lower temperature for a shorter time is desired.

[0003] On the other hand, the reliability of the package is particularly important in terms of solder crack resistance, but the die attach paste is also required to have low stress in order to reduce the difference in linear expansion between the silicon chip and the lead frame. It is. Epoxy resin, cyanate resin, bismaleimide resin, and the like are known as the base resin of the die attach paste. For example, the resin can be cured within 30 seconds and has properties (adhesiveness, low stress property) suitable for each application. ) Were not found at all. Further, even if the properties are satisfied, the viscosity at room temperature increases too much, and there are only materials that are not suitable for use.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been completed as a result of intensive studies to find a die attach paste which can maintain the characteristics of a conventional die attach paste and can be cured even in a very short time. It is.

[0005]

The present invention provides (A) an isocyanuric acid ethylene oxide-modified diacrylate or triacrylate represented by the general formula (1), (B) a diacrylate represented by the general formula (2) and / or Or dimethacrylate, (C) a phosphate group-containing acrylate represented by the general formula (3) and / or a phosphate group-containing methacrylate represented by the general formula (4), (D) an alkoxysilane having an alicyclic epoxy group, A die attach paste comprising (E) an organic peroxide and / or an azo compound, and (F) an inorganic filler.

[0006]

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In a more preferred embodiment, (A) the ethylene oxide-modified diacrylate or triacrylate represented by the general formula (1) and (B) the diacrylate and / or diacrylate represented by the general formula (2) A die attach paste having a weight ratio to methacrylate of 80/20 to 20/80. A semiconductor device manufactured using the above-mentioned die attach paste.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylate resin used in the present invention comprises an isocyanuric acid ethylene oxide-modified diacrylate or triacrylate represented by the general formula (1) and a diacrylate and / or dimethacrylate represented by the general formula (2). The weight ratio is preferably from 80/20 to 20/80. If it is higher than 80/20, the viscosity of the paste is too high, and the workability of the application becomes extremely poor. On the other hand, if it is smaller than 20/80, the adhesiveness and the heat resistance deteriorate.

Examples of the diacrylate and / or dimethacrylate represented by the general formula (2) include dimethylol tricyclodecane di (meth) acrylate.

In the present invention, other acrylate resins may be mixed and used. Other acrylate resins when mixed with the acrylate resin include, for example, urethane acrylates and polyester acrylates obtained by the reaction of hydroxyalkylacrylic acid, polyalkylene glycol and diisocyanate.

Next, the total amount of the components (C) and (D) is 0.1% based on the total weight of the components (A) and (B).
It is preferable that 001 ≦ (C + D) / (A + B) ≦ 0.1. If it is less than 0.001, no effect is exerted on the adhesiveness, and if it is more than 0.1, the adhesiveness is reduced due to voids during curing.

In the present invention, component (C) and component (D) are essential components, and even if one of them is missing, the present invention cannot be realized. The composition ratio is preferably 0.1 ≦ C / D ≦ 10. If it is less than 0.1, the concentration of the alkoxysilane becomes low, and the effect on the adhesive interface is reduced. Also,
If it exceeds 10, the phosphate group concentration becomes too high and acts on the bonding interface more than necessary, thereby lowering the adhesiveness.

Next, examples of the polymerization initiator include organic peroxides and azo compounds. The decomposition temperature of the organic peroxide in a rapid heating test (decomposition start temperature when 1 g of a sample is placed on an electric heating plate and heated at a rate of 4 ° C./min) is preferably from 40 ° C. to 140 ° C. When the decomposition temperature is lower than 40 ° C., the storage stability at room temperature becomes poor,
When the temperature exceeds ℃, the curing time becomes extremely long.

Examples of the organic peroxide used in the present invention include cumylperoxyneodecanate, t-butylperoxyneodecanate, 1-cyclohexyl-1-
Methyl ethyl peroxy neodecaneate, 1,1,3
3-tetramethyl peroxyneodecane, 1,1,
3,3-tetramethylbutylperoxy-2-ethylhexanate, bis (4-butylcyclohexyl) peroxydicarbonate, t-butylperoxyisopropyl monocarbonate, 1,1-bis (t-butylperoxy)- 3,3,5-trimethylcyclohexane, t-
Butyl peroxybenzoate, t-butyl peroxy 3,5,5-trimethyl hexanate, t-butyl peroxy-2-ethylhexyl monocarbonate, t-hexyl peroxy-2-ethyl hexanate and the like.
Examples of the azo compound include 2,2′-azobisisobutylnitrile and 1,1′-azobis (1-acetoxy-1
-Phenylethane).

These organic peroxides and azo compounds can be used alone or in combination of two or more to control curability. Further, various polymerization inhibitors can be added in advance in order to improve the storage stability of the resin.

The addition amount of these organic peroxides and azo compounds is 0.1% based on the total weight of component (A) + component (B).
Preferably it is between 5% and 5% by weight. If the amount is more than 5% by weight, the life of the paste (viscosity change with time) is large, which causes a problem in workability. If the amount is less than 0.1% by weight, the curability is remarkably reduced, which is not preferable.

Examples of the inorganic filler used in the present invention include conductive fillers such as silver powder, gold powder, nickel powder, and copper powder, and insulating fillers such as aluminum nitride, calcium carbonate, silica, and alumina.

Silver powder is used for imparting conductivity,
The content of ionic impurities such as halogen ions and alkali metal ions is preferably 10 ppm or less. In addition, as the shape of the silver powder, a flake shape, a tree shape, a spherical shape, or the like is used. The particle size of the silver powder to be used varies depending on the viscosity of the paste required, but the average particle size is usually 2 to 10 μm.
m, the maximum particle size is preferably about 50 μm. Also,
A mixture of relatively coarse silver powder and fine silver powder can be used, and various shapes may be conveniently mixed.

Next, the silica filler as one of the insulating fillers preferably has an average particle size of 1 to 20 μm and a maximum particle size of 50 μm or less. If the average particle size is less than 1 μm, the viscosity increases, and if the average particle size exceeds 20 μm, bleeding occurs because the resin component flows out during coating or curing, which is not preferable.
On the other hand, if the maximum particle size exceeds 50 μm, it is not preferable because needle clogging occurs when applying the paste with a dispenser. Furthermore, a relatively coarse silica filler and a fine silica filler may be mixed and used, and various shapes may be conveniently mixed.

In the resin paste of the present invention, additives such as an antifoaming agent, a surfactant and an elastomer can be used if necessary.

In the present invention, the use of an acrylate resin has succeeded in significantly increasing the curing reaction rate as compared with the conventional epoxy resin system. In addition, in the acrylate resin system, a phenomenon was observed in which the insulating paste did not have an adhesive strength due to a remarkable decrease in the elastic modulus as compared with the silver paste, but a bifunctional compound having a bulky substituent as a reactive diluent ( The phenomenon was prevented by increasing the crosslinking density by using (meth) acrylate. In this case, the role of the bulky substituent is to improve heat resistance and reduce curing shrinkage.

As a method for producing the paste of the present invention, for example, there is a method in which the paste is preliminarily mixed, a paste is obtained using a three-roll mill or the like, and defoaming is performed under vacuum. A semiconductor device can be manufactured by bonding a semiconductor element to a lead frame or the like using the die attach paste of the present invention, and since these semiconductor devices maintain the conventional characteristics, they have high reliability and high productivity. Since it is high, an excellent semiconductor device can be obtained. As a method for manufacturing a semiconductor device, a conventionally known method can be used.

[0023]

The present invention will be specifically described below with reference to examples. <Examples 1 to 7> Isocyanuric acid ethylene oxide-modified diacrylate (M-215, manufactured by Toagosei Co., Ltd.) represented by the general formula (1), dimethylol tricyclodecane diacrylate (Kyoeisha Chemical Co., Ltd.) Made, DCP-
A), Phosphate group-containing methacrylate (PM-21, manufactured by Nippon Kayaku Co., Ltd.) and alicyclic epoxyalkoxysilane (Shin-Etsu Chemical Co., Ltd., KB) as a coupling agent
M303), the following organic peroxides 1 as polymerization initiators:
2, an azo compound, and an average particle size of 3 as an inorganic filler
μm, flaky silver powder having a maximum particle size of 20 μm, or silica filler having an average particle size of 5 μm and a maximum particle size of 20 μm were blended as shown in Table 1 and kneaded using a three-roll mill to obtain a paste after defoaming. . The obtained paste was evaluated by the following method.

<Evaluation method> Viscosity: 2.5 rpm using an E-type viscometer at 25 ° C.
The viscosity in m was measured. -Storage property: The viscosity after standing for 72 hours in a thermostat at 25 ° C was measured. If the increase in viscosity was 10% or less of the initial viscosity, it was good, and if it exceeded 10%, it was bad. Adhesive strength: A 2 × 2 mm silicon chip was mounted on a copper frame using a paste and cured in an oven at 180 ° C. for 15 minutes. After curing, the die shear strength under heat at 250 ° C. was measured using a push-pull gauge. Void: A glass chip of 10 mm × 10 mm was mounted on a lead frame, and after curing, the appearance was visually checked for voids. A void of 15% or less of the adhered area was regarded as good, and a void exceeding 15% was regarded as defective. -Peeling during WB processing: 6 mm x 15 m on lead frame
The m-shaped chip was mounted, and after curing, a wire bonding treatment was performed at 250 ° C., and the adhesion state of the pellet was observed. If there was no peeling, it was good. If peeling was observed, it was bad. -Warpage: Warpage was measured as an evaluation of low stress. Thickness 2
6mm x 15mm x 0.3 in a 00 micron copper frame
mm silicon chip at 175 ° C 15
The paste was adhered so that the thickness of the paste became 20 μm in seconds, the displacement of the chip in the longitudinal direction was measured using a surface roughness meter, and the amount of warpage was measured based on the height difference. -Package crack resistance: Sumicon EME-7320
A package molded under the following conditions using a sealing material (manufactured by Sumitomo Bakelite Co., Ltd.) at 85 ° C. and a relative humidity of 85
% After a water absorption treatment for 168 hours, followed by IR reflow (240
(10 ° C., 10 seconds), the number of internal cracks was measured by cross-sectional observation, and used as an index of package crack resistance. Package: 80pQFP (14 × 20 × 2mm thickness) Chip size: 7.5 × 7.5mm (aluminum wiring only) Lead frame: Cu Molding: 175 ° C, 2 minutes Post-mold cure: 175 ° C, 4 hours Total number of packages : 12

<Comparative Examples 1 to 7> Each component having the composition shown in Table 2 was blended, a paste was obtained in the same manner as in Example 1, and the same evaluation was performed.

The evaluation results are shown in Tables 1 and 2.

[Table 1]

[0027]

[Table 2]

[0028]

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Organic peroxide 1: Cumyl peroxyneodecanate, manufactured by NOF Corporation (decomposition temperature in a rapid heating test: 65 ° C.) Organic peroxide 2: manufactured by NOF Corporation, t -Butyl peroxyisopropyl monocarbonate (decomposition temperature in rapid heating test: 108 ° C) Azo compound: 2,2'-azoisobutylnitrile, manufactured by Wako Pure Chemical Industries, Ltd.

[0030]

According to the die attach paste of the present invention, the adhesion is improved by an isocyanuric ethylene oxide-modified diacrylate or triacrylate having a limited structure, and the crosslink density is increased by using a diacrylate having a bulky substituent. As a result, the insulating paste is a fast-curing paste having excellent low-stress and adhesive properties. Furthermore, a semiconductor device manufactured using the die attach paste of the present invention has high productivity while maintaining the conventional characteristics.

Claims (3)

[Claims] 1. An isocyanuric acid ethylene oxide-modified diacrylate or triacrylate represented by the general formula (1), (B) a diacrylate and / or dimethacrylate represented by the general formula (2), and (C) a general formula (1). A phosphate group-containing acrylate represented by the formula (3) and / or a phosphate group-containing methacrylate represented by the general formula (4),
(D) an alkoxysilane having an alicyclic epoxy group,
A die attach paste comprising (E) an organic peroxide and / or an azo compound, and (F) an inorganic filler. Embedded image Embedded image Embedded image Embedded image 2. A weight of (A) the isocyanuric acid ethylene oxide-modified diacrylate or triacrylate represented by the general formula (1) and (B) the diacrylate and / or dimethacrylate represented by the general formula (2). The ratio is 8
The die attach paste according to claim 1, wherein the ratio is 0/20 to 20/80. 3. A semiconductor device manufactured using the die attach paste according to claim 1.