JPH11181244A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent moldability, soldering resistance and electric characteristics at high temperatures by compounding epoxy resins containing stilbene type epoxy resins, a phenolic resin-curing agent, an inorganic filler, a curing-accelerating agent, a brominated epoxy resin, an antimony oxide and a bismuth-based inorganic ion exchanger. SOLUTION: This epoxy resin composition comprises (A) epoxy resins containing the mixture of a stilbene type epoxy resin of formula I (R1 -R4 are each H, a 1-6C alkyl or a halogen; aryl groups bound to the C=C bond are the same as each other) with a stilbene type epoxy resin of formula II (R5 -R12 are each H, a 1-6C alkyl or a halogen; aryl groups bound to the C=C bond are different from each other) in an amount of >=30 wt.% based on the total amount of the epoxy resins, (B) a phenolic resin-curing agent, (C) an inorganic filler, (D) a curing-accelerating agent, (E) a brominated epoxy resin, (F) antimony trioxide or antimony pentoxide, and (G) a bismuth-based inorganic ion exchanger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in moldability, solder resistance and reliability, particularly, electrical characteristics at high temperatures, and a semiconductor device using the same. .

[0002]

2. Description of the Related Art In recent years, instead of ceramic encapsulation or metal encapsulation, inexpensive thermosetting resin molding materials, particularly epoxy resin, have been used for encapsulation of semiconductor elements such as ICs and LSIs. At present, the method of doing so is widely adopted. However, the miniaturization, weight reduction, and high performance of electronic products have increased the density of semiconductor devices, and the surface mounting of semiconductor packages has spurred thinner packages. Is becoming increasingly tough. For this reason, a problem that cannot be solved by the conventional epoxy resin composition has appeared. The biggest problem is that the package is exposed to a high temperature of 200 ° C or more during the solder immersion or reflow process due to the adoption of the surface mounting of the semiconductor package. Of various plated joints or LOC (Lea
In a package having a (d on Chip) structure, peeling occurs at each interface between a polyimide tape adhesive or the like and a cured product of the epoxy resin composition, and the reliability is significantly reduced. In addition, one of the causes of the decrease in the moisture resistance reliability of the sealing resin, particularly the corrosion of the Al wiring, is an impurity of the epoxy resin composition. Examples of the impurity include sodium, chlorine, and bromine. Among these, sodium and chlorine have been reduced to almost no problem by the production method and purification of the raw materials. On the other hand, bromine is difficult to reduce because bromine is generated from a brominated epoxy resin used as a flame retardant. Several methods of adding non-bromine flame retardants have been proposed, but due to the balance of moldability, reliability, and price, brominated epoxy resins are currently used as flame retardants for epoxy resins for semiconductor encapsulation. The antimony / antimony oxide system is the most common, and some countermeasures are required.

Further, in recent years, the thickness of the epoxy resin composition occupying in the package has been further reduced with the reduction in the thickness of the package, and a 1 mm-thick TSOP is becoming mainstream in packages for 64M and 256M DRAMs. These thin packages are required to have good package filling properties during molding of the epoxy resin composition, have little gold wire deformation, and have no chip or lead frame deformation (called chip shift or die pad shift). ,
The epoxy resin composition needs to have excellent fluidity during molding. In order to achieve both improvement in reliability due to soldering and improvement in fluidity during molding, the amount of fused silica powder in the epoxy resin composition is increased to reduce moisture absorption, increase strength, and reduce thermal expansion. And improving the solder resistance, and using a resin having a low melt viscosity to maintain high viscosity and low viscosity during molding is becoming common. As the epoxy resin used in this method, there is a crystalline epoxy resin which is solid at ordinary temperature and extremely lowers in viscosity when molten, and as a typical example, a biphenyl type epoxy resin has begun to be widely used. (JP-A-5-175364, JP-A-5-343570, JP-A-6-80763, etc.).

[0004] However, conventional crystalline epoxy resins, particularly biphenyl type epoxy resins, are characterized by low melt viscosity at the molding temperature, but the biphenyl structure, which is the main skeleton thereof, has a limit of the number of functional groups of only two functions. In addition, it has been pointed out that there is a problem in that the properties of the cured product such as the heat strength and the glass transition temperature are low. In addition, a problem has begun that electrical characteristics deteriorate when a semiconductor package sealed with an epoxy resin composition using a biphenyl type epoxy resin is treated at a high temperature of 150 ° C. or higher for a long time. It has been found that the cause is greatly affected by the low glass transition temperature of the cured product of the biphenyl type epoxy resin, and improvement is desired.

[0005]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in moldability, solder resistance, reliability, especially electrical characteristics at high temperatures, and a semiconductor device using the same. Is what you do.

[0006]

According to the present invention, there is provided a method for preparing a mixture of (A) a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) in a total epoxy resin. Epoxy resin containing at least 30% by weight,
(B) a phenolic resin curing agent, (C) an inorganic filler,
(D) curing accelerator, (E) brominated epoxy resin, (F)
An epoxy resin composition for encapsulating a semiconductor, comprising diantimony trioxide or diantimony pentoxide, (G) a bismuth-based inorganic ion exchanger, and sealed with an epoxy resin composition. Semiconductor device.

Embedded image (Where R _{1 to} R ₄ are each independently a hydrogen atom,
A group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms or halogen. The two aryl groups attached to the carbon-carbon double bond are the same as each other. )

[0007]

Embedded image (Where R _{5 to} R ₁₂ are each independently a hydrogen atom,
A group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms or halogen. The two aryl groups attached to the carbon-carbon double bond are different from each other. )

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy resin in the component (A) used in the present invention is a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2). Many studies have been made on this stilbene type epoxy resin, and many reports have been published. Some applications to semiconductor sealing materials have also been proposed (JP-A-6-345849, JP-A-8-73562, etc.). Since this stilbene skeleton has a rigid planar or rod-like structure, molecules are easily aligned, and is a typical structure of liquid crystal or liquid crystalline polymer. An epoxy resin composition using a resin having this structure exhibits good heat resistance due to the rigid molecular skeleton of the epoxy resin after curing and the orientation of the molecules. For this reason, it has features such as higher glass transition temperature and heat strength and superior moisture resistance as compared with biphenyl type epoxy resin which is a typical crystalline epoxy resin. Further, since the glass transition temperature is higher than that of the biphenyl type epoxy resin, the deterioration of the electrical characteristics of the semiconductor device sealed with the epoxy resin composition using the same in a high temperature atmosphere is higher than that in the case where the biphenyl type epoxy resin is used. There are also few features. Further, since the epoxy resin is liable to orient molecules due to shear stress, the epoxy resin composition using the epoxy resin can be used in a low pressure transfer molding in a mold (particularly a structure having a structure in which shear stress is easily applied like a thin package). High flowability in the mold) and excellent filling in thin packages. Therefore, it is an epoxy resin suitable for the resin composition for thin package sealing which is the object of the present invention.

The substituents R _{1 to} R ₁₂ of the stilbene type epoxy resins represented by the general formulas (1) and (2) are each a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms,
Or a group or atom selected from halogens, which may be the same or different, such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group (Including each isomer), a cyclohexyl group, a chlorine atom, a bromine atom, and the like. Particularly, a methyl group, an ethyl group, a propyl group, or a butyl group is preferable in view of the low melt viscosity of the epoxy resin. This epoxy resin is a mixture of a stilbene type epoxy resin of the general formula (1) and a stilbene type epoxy resin of the general formula (2).
The stilbene type epoxy resin represented by the general formula (2) has various structures depending on the type of the substituent. Mixing of the stilbene-type epoxy resin of the general formula (1) and the stilbene-type epoxy resin of the general formula (2) only needs to lower the melting point by mixing both resins, and the mixing method is not particularly limited. For example, there is a method of mixing stilbene-type phenols, which are raw materials of the stilbene-type epoxy resin, before glycidyl etherification, or a method of melt-mixing both stilbene-type epoxy resins.

As the stilbene type epoxy resin represented by the general formula (1), 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylstilbene and 4,4′- Dihydroxy-3,3'-ditert-butyl-6,6'-dimethylstilbene, 4,4'-dihydroxy-3,3'-ditert-butyl-5,5 '
Glycidyl etherified dimethylstilbene is particularly preferred. As the stilbene type epoxy resin represented by the general formula (2), 5-tert-butyl-4,4′-dihydroxy-2,3 ′, 5′-trimethylstilbene and 3-tert-butyl are preferred in terms of performance and raw material price. Glycidyl etherified products of -4,4'-dihydroxy-3 ', 5,5'-trimethylstilbene are particularly preferred. General formula (1)
The stilbene type epoxy resin of the formula (2) and the stilbene type epoxy resin of the general formula (2) are used as a mixture, and the ratio thereof is [formula (1) / formula (2) = 20 to 80% by weight / 80].
To 20% by weight]. Outside this range, the viscosity may increase.

The epoxy resin which can be used in combination with the epoxy resin (A) used in the present invention refers to all monomers, oligomers and polymers having an epoxy group, such as bisphenol A type epoxy resin and orthocresol novolak type epoxy resin. Resin, naphthol type epoxy resin, triphenolmethane type epoxy resin, dicyclopentadiene-modified phenolic epoxy resin and the like.In particular, in order to obtain an epoxy resin composition having excellent solder resistance, biphenol diglycidyl ether type Epoxy resin, tetramethylbiphenol diglycidyl ether type epoxy resin, hydroquinone diglycidyl ether type epoxy resin, tetramethylbisphenol F
Represented by diglycidyl ether type epoxy resin, etc.
Epoxy resins that exhibit crystallinity at room temperature are preferred. The epoxy resin used in combination with the general formulas (1) and (2) is
They may be used alone or as a mixture. The proportion of the total stilbene type epoxy resin used in the present invention is desirably 30% by weight or more in the total epoxy resin. When the content is less than 30% by weight, the high fluidity and high heat resistance at the time of molding, which are characteristics of the crystalline epoxy resin, are not exhibited.

The phenolic resin curing agent (B) used in the present invention refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in one molecule. For example, a phenol novolak resin, a cresol novolak resin, a para-xylylene-modified phenol resin, a para-xylylene / met-xylylene-modified phenol resin, a terpene-modified phenol resin, a dicyclopentadiene-modified phenol resin, and the like may be used, and these may be used alone or in combination. These phenol resins can be used without any limitation in molecular weight, softening point, hydroxyl equivalent, and the like. The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenolic resins is preferably 0.5 to 2, particularly preferably 0.7 to 2.
1.5. If it is out of the range of 0.5 to 2, curability,
It is not preferable because the moisture resistance and the like are lowered.

The inorganic filler of the component (C) used in the present invention includes fused silica powder, crystalline silica powder, alumina and the like, and is further obtained by hydrolyzing tetramethoxysilane, tetraethoxysilane and the like. Refers to silica. The silica is classified into spherical silica and crushed silica according to its shape and manufacturing method. Either of them may be used. However, when the inorganic filler is highly filled, it is preferable to increase the use ratio of the spherical silica. The compounding amount of the inorganic filler is preferably from 75 to 93% by weight in the entire epoxy resin composition. If it is less than 75% by weight, the moisture absorption of the molded package increases and the strength at the solder processing temperature decreases, so that
It is not preferable because cracks easily occur in the package during the soldering process. On the other hand, if it exceeds 93% by weight, the fluidity of the epoxy resin composition during molding is reduced, and there is a possibility that poor filling may occur during molding, which is not preferable.

The curing accelerator of the component (D) used in the present invention may be any as long as it promotes the crosslinking reaction between the epoxy resin and the phenol resin curing agent.
1,8-diazabicyclo (5,4,0) undecene-7
And the like, an organic phosphorus compound such as triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salt, and an imidazole compound such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture.

The brominated epoxy resin of the component (E) used in the present invention refers to all epoxy resins having a bromine atom in the resin skeleton, and these are well-known flame retardants. Bromine atoms in the brominated epoxy resin exhibit a flame retardant action when the cured product of the epoxy resin composition burns. Specifically, a tetrabromobisphenol A type epoxy resin, a brominated phenol novolak type epoxy resin and the like are particularly preferable. The component (F) used in the present invention is diantimony trioxide or diantimony pentoxide, which is well known and widely used as a flame retardant.

The component (G) used in the present invention is a bismuth-based inorganic ion exchanger, particularly preferably a bismuth hydroxide or a hydroxide of bismuth or silicon containing at least 10000 ppm of nitrate ions. This nitrate ion acts as a weak anion exchanger, and exchanges both halogen ions by exchanging with chlorine ions and bromine ions released from the phenolic resin curing agent, brominated epoxy resin, etc. incorporated in the epoxy resin composition. It captures and prevents corrosion of the aluminum wiring. If the content of nitrate ions is less than 10,000 ppm, sufficient ion exchange action cannot be achieved, and there is a possibility that moisture resistance reliability such as corrosion of aluminum wiring may be reduced. Preferred bismuth-based inorganic ion exchangers include the following composition formulas (a) and (b)
It is represented by _{BiOx (OH) y (NO 3} ) z · nH 2 O (a) ( where, x = 0.9~1.1, y = 0.6~0.8 , z = 0.2~0.4, n
= 0.3 to 1.0) BiSiwOx (OH) y (NO ₃ ) z · nH ₂ O (b) (however, w = 0.03 to 0.15, x = 0.9 to 1.1, y = 0.6 to 0.8, z
= 0.2-0.4, n = 0.5-1.4) The above-mentioned inorganic ion exchangers may be used alone or as a mixture. This inorganic ion exchanger is preferably contained in the entire epoxy resin composition in an amount of 0.2 to 2% by weight.

The inorganic ion exchanger of the component (G) captures these ions and prevents the deterioration of the electric characteristics under a high temperature atmosphere. Accordingly, the stilbene type epoxy resin as the component (A) can be further improved without impairing the feature of being excellent in electric characteristics under a high temperature atmosphere. That is, it is possible to achieve both high fluidity at the time of molding an epoxy resin composition using a crystalline epoxy resin and improvement of electric characteristics under a high-temperature atmosphere.

The epoxy resin composition of the present invention comprises (A)
In addition to the component (G), a low-stress agent represented by a polysiloxane compound, a coupling agent, a coloring agent represented by carbon black, a release agent such as a natural wax and a synthetic wax, and the like can be appropriately compounded as necessary. It is. In order to obtain a molding material, after mixing all components, the mixture is heated and kneaded using a heating kneader or a hot roll, and then cooled and pulverized to obtain a desired resin composition. Using the epoxy resin composition of the present invention to encapsulate electronic components such as semiconductors and manufacture semiconductor devices, transfer molding, compression molding, and injection molding can be performed by conventional molding methods such as molding. .

[0019]

The present invention will be specifically described below with reference to examples. << Example 1 >> 3.4 parts by weight of epoxy resin having a structure of formula (3) as a main component 2.2 parts by weight of epoxy resin having a structure of formula (4) as a main component ・ shown by formula (5) phenolic resin 4.4 parts by weight of bismuth inorganic ion exchanger 0.5 part by weight [formula _{BiSiwOx (OH) y (NO 3} ) z · nH 2 O, nitrate ions 40000ppm that, manufactured by Toagosei Co., Ltd. IXE-530S 86 parts by weight of fused spherical silica 0.2 parts by weight of 1,8-diazabicyclo (5,4,0) undecene-7 [hereinafter referred to as DBU] 1.0 part by weight of antimony trioxide [antimony atom content 79%] -Carbon black 0.3 parts by weight-Brominated bisphenol A type epoxy resin [bromine content 50%] 1.0 parts by weight-γ-glycidoxypropyltrimethoxysilane 0.5 parts by weight-Carnauba wax 0 After mixing each component using a mixer, the surface temperature was 90 parts by weight.
The mixture was kneaded 30 times using two rolls at a temperature of 45 ° C. and a temperature of 45 ° C. The obtained kneaded material sheet was cooled and pulverized to obtain a resin composition.
The properties of the obtained resin composition were evaluated by the following methods. Table 1 shows the results.

[0020]

Embedded image

Embedded image

Embedded image

<< Evaluation Method >> Spiral flow: Using a mold for measuring spiral flow according to EMMI-I-66, mold temperature 175
C., injection pressure was 70 kg / cm ² , and curing time was 2 minutes. -Bacoal hardness: 16 pSO used in evaluation of high temperature reliability
P package at 175 ° C mold temperature, 75kg / cm
Was transfer molded for 2 minutes at ² of the molding pressure. Ten seconds after the mold was opened, the surface hardness of the molded product was measured with a Bacol hardness tester # 935. -Flame resistance: 1.0 mm according to the UL-94 test method
Thickness test pieces were fired. The results are expressed as the UL-94 flame resistance level. -High-temperature reliability: when a 16pSOP equipped with a simulated element was used and processed at 185 ° C, the electrical resistance value was 2 times the initial value.
The processing time until the number of packages to be doubled exceeds 50% is shown.

Heat strength: The bending strength at 240 ° C. is determined by JI
It measured according to S-K6911. Solder resistance: 100-pin TQFP (package size: 14 x 14 mm, thickness: 1.4 mm, silicon chip size: 8.0 x 8.0 mm, lead frame made of 42 alloy), mold temperature of 175 ° C, 75 kg / Transfer molding was performed for 2 minutes at an injection pressure of 2 cm ² , and at 175 ° C. for 8 minutes.
After time curing. The molded product package was left for 168 hours in an environment of 85 ° C. and 85% relative humidity, and then 240
C. for 10 seconds. The package was observed with a microscope, and external cracks were indicated by [(number of packages in which cracks occurred) / (number of all packages) × 100]%. The ratio of the peeled area between the chip and the resin composition was measured using an ultrasonic flaw detector, and the peeling rate was expressed as [(peeled area) / (chip area) × 100]%.

<< Examples 2 to 5, Comparative Examples 1 to 5 >> Example 1
Was replaced with each other in the proportions shown in Tables 1 and 2, and mixed and kneaded in the same manner as in Example 1 to obtain a resin composition. Tables 1 and 2 show the results of the evaluation performed in the same manner as in Example 1. Other materials used in Examples and Comparative Examples are as follows.・ Biphenyl type epoxy resin [Yukaka Epoxy Co., Ltd.]
YX-4000H]

・ Phenolic resin (6)

Embedded image ・ Phenolic resin (7)

Embedded image

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

As described above, the use of the epoxy resin composition of the present invention makes it possible to provide a thin semiconductor package with excellent filling properties, and to obtain an electrical property under a high-temperature atmosphere.
Excellent reliability and solder resistance after moisture absorption.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/22 C08K 3/22 H01L 23/29 H01L 23/30 R 23/31

Claims (4)

[Claims] (A) an epoxy resin comprising a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) in an amount of 30% by weight or more in a total epoxy resin; (B) phenolic resin curing agent, (C) inorganic filler, (D) curing accelerator, (E) brominated epoxy resin, (F) diantimony trioxide or diantimony pentoxide (G) bismuth-based inorganic ion exchange An epoxy resin composition for encapsulating a semiconductor, comprising a body. Embedded image (Here, R _{1 to} R ₄ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. Carbon-carbon double The two aryl groups attached to the bond are the same as each other) (Where R _{5 to} R ₁₂ are each independently a hydrogen atom,
A group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms or halogen. The two aryl groups attached to the carbon-carbon double bond are different from each other. ) 2. The epoxy resin for semiconductor encapsulation according to claim 1, wherein the bismuth-based inorganic ion exchanger as the component (G) is a bismuth hydroxide or a bismuth or silicon hydroxide containing at least 10000 ppm of nitrate ions. Composition. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the bismuth-based inorganic ion exchanger as the component (G) is a compound represented by the following composition formulas (a) and (b). Stuff. _{BiOx (OH) y (NO 3} ) z · nH 2 O (a) ( where, x = 0.9~1.1, y = 0.6~0.8 , z = 0.2~0.4, n
= 0.3 to 1.0) BiSiwOx (OH) y (NO ₃ ) z · nH ₂ O (b) (where w = 0.03 to 0.15, x = 0.9 to 1.1, y = 0.6 to 0.8, z
= 0.2-0.4, n = 0.5-1.4) 4. A semiconductor device comprising a semiconductor encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1, 2 or 3.