JPH11293089A - Epoxy resin composition and ferroelectrics memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide epoxy resin compositions excellent in retention of ferroelectricity of ferroelectrics memory. SOLUTION: A desired epoxy resin composition comprises (A) an epoxy resin; (B) a phenolic resin curing agent; (C) an inorganic filler; (D) a curing promoter; and (E) one or more members selected from a non-organosilicon compound type stress reducing agent and an organosilicon compound as the essential components, and has an amount of hydrogen gas generated after heating at 175 deg.C for 90 minutes of not more than 20 nmol per gram of the total resin composition and, preferably an amount of hydrogen gas generated after heating of the non-organosilicon compound type stress reducing agent or the organosilicon compound at 175 deg.C for 90 minutes of not more than 0.5 μmol per gram, and the compounding amount of the one or more members selected from a non-organosilicon compound type stress reducing agent and an organosilicon compound being not greater than 4.0 wt.% of the total resin composition. Ferroelectrics memory devices are sealed with this epoxy resin composition.

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 encapsulating a semiconductor which has an extremely small amount of hydrogen gas generation and is excellent in the ferroelectric retention of a ferroelectric memory, and a ferroelectric memory encapsulated thereby. It concerns the device.

[0002]

2. Description of the Related Art In recent years, a memory semiconductor device sealed with plastic has been highly integrated, and a structure using a ferroelectric has been considered to be effective as a memory cell material. However, when these ferroelectric memories are sealed using a conventional epoxy resin composition for semiconductor encapsulation, there has been a problem that ferroelectric characteristics cannot be maintained. It has been found that a very small amount of hydrogen gas is generated during heating from a conventional semiconductor encapsulating material.
It has been found that even in hydrogen gas of m or ppb unit, in a ferroelectric memory element, this very small amount of hydrogen gas that has passed through the protective film of the silicon chip deteriorates the ferroelectric characteristics of the ferroelectric element. Attention has also been focused on the amount of hydrogen gas generated in ppm and ppb as a new problem.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation and a ferroelectric memory device which are excellent in maintaining ferroelectric characteristics of a ferroelectric memory.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in view of the above-mentioned problems. The inventors have found that the ferroelectric properties of the body memory can be maintained, and in particular, have found that the SiH group contained in the organic silicon compound is a hydrogen gas generating source, and have completed the present invention.

That is, the present invention provides (A) an epoxy resin,
(B) a phenolic resin curing agent, (C) an inorganic filler,
The resin contains at least one selected from (D) a curing accelerator, (E) a non-organic silicon compound-based low-stress agent, and an organic silicon compound. An epoxy resin composition for encapsulating a ferroelectric memory, wherein the epoxy resin composition is 20 nmol or less per 1.0 g of the composition. The amount of hydrogen gas generated during minute heating is 0.5 micromol or less per 1.0 g,
An epoxy resin composition for encapsulating a ferroelectric memory, wherein a compounding amount of at least one selected from a non-organic silicon compound-based low stress agent and an organic silicon compound is 4.0% by weight or less in the total resin composition. . Further, there is provided a ferroelectric memory device characterized in that a ferroelectric memory is sealed using the epoxy resin composition described above.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the total amount of hydrogen gas generated when an epoxy resin composition is heated at 175 ° C. for 90 minutes is 20 nmol or less per 1.0 g. It has been found that it is an organic silicon compound. Organic silicon compounds contain SiH groups, which easily generate hydrogen gas by heating or the like. Therefore, in the present invention, a non-organic silicon compound-based low stress agent,
At least one selected from organic silicon compounds as an essential component,
An epoxy resin composition for encapsulating ferroelectric memory, characterized in that the amount of hydrogen gas generated after heating at 175 ° C. for 90 minutes is not more than 20 nmol per 1.0 g of the total resin composition; The compound-based low-stress agent, or the amount of hydrogen gas generated when the organosilicon compound is heated at 175 ° C. for 90 minutes is 0.5 μmol or less per 1.0 g,
It is characterized in that the compounding amount of at least one selected from the group consisting of a non-organic silicon compound-based low stress agent and an organic silicon compound is 4.0% by weight or less based on the whole resin composition. Ferroelectric memories have excellent ferroelectricity retention. In order to achieve the ferroelectricity retention of the ferroelectric memory, it is important to keep the amount of hydrogen gas generated from each raw material component low. In particular, an organic silicon compound is a raw material component that easily generates hydrogen gas. These raw material components are usually contained in the sealing resin composition as a coupling agent and a low stress agent. These compounds contain a small amount of SiH groups, which can easily generate hydrogen gas only by heating. This SiH group is mainly a silane compound,
It often remains as an impurity in the starting material of the silicone compound.

[0007] The compounding amount of at least one selected from the group consisting of a non-organic silicon compound-based low stress agent and an organic silicon compound is preferably 4.0% by weight or less in the total resin composition. If it exceeds 4.0% by weight, the amount of hydrogen gas generated from the resin composition increases, which is not preferable.

The non-organic silicon compound-based low stress agent used in the present invention includes acrylonitrile-based rubber, polybutadiene-based rubber, polystyrene-based rubber and the like.
The amount of hydrogen gas generated during heating for 90 minutes is 0.5
Preferably it is less than micromolar. If it exceeds 0.5 μmol, the amount of hydrogen gas generated becomes large, and the ferroelectric retention of the sealed ferroelectric memory is significantly reduced. The amount of the non-organic silicon compound-based low stress agent is preferably 0.2 to 4.0% by weight in the whole resin composition. If it is less than 0.2% by weight, the low stress effect is not exhibited because it is not preferable. If it exceeds 4.0% by weight, the melt viscosity during molding of the resin composition becomes high, and molding defects such as wire sweep and pad shift are caused. It is not preferable because it occurs.

The organic silicon compound used in the present invention includes a silane coupling agent, a silicone oil, a silicone gel,
The term refers to silicone rubber, and the amount of hydrogen gas generated when heated at 175 ° C. for 90 minutes is preferably 0.5 μmol or less per 1.0 g. If it exceeds 0.5 μmol, the amount of hydrogen gas generated becomes large, and the ferroelectric retention of the sealed ferroelectric memory is significantly reduced.

In the silane coupling agent, examples of the functional group substituted on the Si atom include a methoxy group, an epoxy group, a thiol group, a hydroxyl group, an amino group, and a ureide group. In addition to the silane coupling agent, aluminum-based,
It is also possible to use a titanium-based coupling agent or the like in combination. The amount of addition of these coupling agents is preferably 0.2 to 2.0% by weight in the whole resin composition. 0.
If the amount is less than 2% by weight, the coupling effect is reduced, which is not preferable. If the amount is more than 2.0% by weight, molding defects such as burrs and floating oil occur in the molded product, which is not preferable.

In the silicone oil, examples of the functional group substituted by the Si atom include a methoxy group, a phenyl group, an epoxy group, a thiol group, a hydroxyl group, an amino group, a ureide group, and a polyethylene-propylene ether group. The amount of silicone oil added is 0.3 to 0.3% in the total resin composition.
4.0% by weight is preferred. If the amount is less than 0.3% by weight, the effect of reducing the stress is small, and if it exceeds 4.0% by weight, molding defects such as burrs and oil floating occur in the molded product.

Silicone rubber and silicone gel are Si
Examples of the functional group substituted on the atom include a methoxy group, a phenyl group, an epoxy group, a thiol group, a hydroxyl group, an amino group, an ureido group, a polyethylene-propylene ether group, and the like. The addition amount of the silicone rubber and silicone gel is preferably 0.3 to 4.0% by weight in the whole resin composition. If the amount is less than 0.3% by weight, the effect of lowering the stress is small, so that it is not preferable. If the amount exceeds 4.0% by weight, the melt viscosity at the time of molding the resin composition becomes high, and molding defects such as wire sweep and pad shift are caused. It is not preferable because it occurs.

The epoxy resin used in the present invention is a monomer, oligomer or polymer containing an epoxy group in the molecule, and is not particularly limited. Examples include phenol novolak type epoxy resin, bisphenol type epoxy resin, naphthalene type epoxy resin, triphenolmethane type epoxy resin, triazine nucleus containing epoxy resin, and modified resins thereof. In order to improve the moisture resistance of the resin composition, it is preferable that impurity ions such as chlorine ions and sodium ions are as small as possible, and the epoxy equivalent for obtaining good curability is preferably 150 to 300.

The phenolic resin curing agent used in the present invention is a monomer, an oligomer or a polymer containing a phenolic hydroxyl group in the molecule, and is not particularly limited. resin,
Triphenolmethane resins and their modified resins. The hydroxyl equivalent for obtaining good curability of the resin composition is preferably about 80 to 250.

The inorganic filler used in the present invention is selected from fused silica powder, spherical silica powder, crystalline silica powder, alumina and the like. Particularly, a fused silica powder is desirable. Further, the compounding amount is appropriately selected and adjusted according to the required characteristics, since there is a fear that poor moldability due to a decrease in fluidity is used.

The curing accelerator used in the present invention may be any one which promotes the reaction between the epoxy group and the phenolic hydroxyl group, and may be one generally used in a sealing resin composition. Representative examples include 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, benzyldimethylamine, 2-methylimidazole, and the like, and these may be used alone or in combination.

The resin composition of the present invention may further comprise (A) to (E), a flame retardant such as antimony oxide, a coloring agent such as carbon black, and a release agent such as natural wax and synthetic wax, if necessary. May be appropriately compounded. Further, the resin composition of the present invention comprises components (A) to (E),
And other additives and the like are sufficiently and uniformly mixed using a mixer such as a super mixer, and then kneaded with a melt kneader such as a hot roll or a kneader, cooled, and pulverized.
In order to manufacture a ferroelectric memory device by encapsulating a ferroelectric memory using the resin composition of the present invention, it is only necessary to cure and mold by a molding method such as a transfer mold, a compression mold, and an injection mold.

[0018]

EXAMPLES Examples and comparative examples of the present invention will be shown below to specifically explain the present invention. << Example 1 >> The following composition: fused spherical silica powder A (average particle size: 20 μm, specific surface area: 2.5 m ² / g) 76.60 parts by weight o-cresol novolak type epoxy resin (softening point: 62 ° C., epoxy equivalent) 200 g / eq) 14.00 parts by weight Phenol novolak resin (softening point 87 ° C., hydroxyl equivalent 104 g / eq) 7.00 parts by weight Silane coupling agent B 0.40 parts by weight Silicone oil D 1.00 parts by weight・ 0.20 parts by weight of 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) ・ 0.30 parts by weight of carbon black ・ 0.50 parts by weight of carnauba wax at room temperature using a super mixer 70 to 10
The mixture was kneaded with a biaxial roll at 0 ° C., cooled and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following method.
Table 1 shows the results.

Examples 2 to 5 A resin composition was prepared according to the formulation shown in Table 1 to obtain a resin composition in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. << Comparative Examples 1 to
5 >> Compounded according to the formulation in Table 2, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 2 shows the results.

The structural formulas of the other epoxy resins, silane coupling agents, silicone oils and silicone rubbers used, and the amounts of hydrogen gas generated when heated at 175 ° C. for 90 minutes are as follows.・ Epoxy resin of the following formula (1): softening point 62 ° C., epoxy equivalent 257 g / eq ・ Silane coupling agent B: the following formula (2), hydrogen gas generation amount: 0.45 μmol / g ・ Silane coupling agent C: the following formula (2), the amount of hydrogen gas generated: 15.00 μmol / g ・ Silicone oil D: the following formula (3), the amount of hydrogen gas generated: 0.40 μmol / g l of the formula (3) = 3
0, m = 5, n = 20, p = 40 (all are average values) Silicone oil E: the following formula (3), hydrogen gas generation amount: 10.00 μmol / g Silicone rubber powder F: hydrogen gas Generation amount: 0.40 micromol / g Silicone rubber powder G: generation amount of hydrogen gas; 13.00
Acrylonitrile butadiene rubber powder H (acrylonitrile content 25% by weight) Hydrogen gas generation amount: not detected

[0021]

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[0022]

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[0023]

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<< Evaluation Method >> A method for measuring the amount of hydrogen gas generated: In a sealed glass tube, approximately 0.70 g of a sample of an epoxy resin composition or a non-organic silicon compound-based low-stress agent and an organic silicon compound was precisely weighed. And then connected to a nitrogen cylinder and a measuring instrument with a glass wool plug, heated at 175 ° C. for 90 minutes, guided the generated gas to the measuring instrument with a nitrogen stream, and measured the amount of hydrogen gas. RGA manufactured by TRACE ANALYTICAL
5 Using ProcessGas Analyzer,
The number of moles of hydrogen gas generated per 1.0 g of the sample was determined. -Spiral flow: Using a test mold according to EMMI-I-66, mold temperature 175 ° C, injection pressure 70kgf
Spiral flow was measured at a curing time of 120 seconds / cm ² . (Unit: cm) ・ Production of SOP type package: A ferroelectric memory element is mounted, and a low-pressure transfer molding machine is used at 175 ° C.
A 16-lead SOP type package for testing wire flow, solder crack resistance, and solder moisture resistance at a pressure of 70 kgf / cm ² and a curing time of 90 seconds [Lead frame is copper, dimensions are 6.0 × 13.5. × thickness 4.0mm (hereinafter, S
OP type 16L package)].

Fillability: When the SOP type 16L package was molded, the presence or absence of an unfilled portion was visually observed. -Solder crack resistance: The SOP type 16L package was post-cured at 175 ° C for 4 hours. Next, the sample was subjected to a moisture absorption treatment in a constant temperature / humidity bath at 85 ° C. and a relative humidity of 60% for 168 hours, and further heat-treated in an IR reflow furnace at 240 ° C. The obtained package was inspected for defects using an ultrasonic flaw detector. The peeling and cracking of the interface inside the package were regarded as defective, and the number of defective packages with respect to a total of 24 packages was determined and expressed as the number of defectives / total. -Solder moisture resistance test: The SOP type 16L package was post-cured at 175 ° C for 4 hours. Next, a moisture absorption treatment was performed for 168 hours in a thermo-hygrostat at 85 ° C. and a relative humidity of 60%.
Further, heat treatment was performed in an IR reflow furnace at 240 ° C. afterwards,
Pressure cooker test (120 ° C, relative humidity 100
%), And the open failure of the circuit was measured. Total 24
The defect rate was determined from the number of defective packages for each package, and the time when the defect rate became 50% was defined as the average life. (Unit is time) Ferroelectricity retention test: Circuit failure was measured using the SOP type 16L package described above. The number of defective packages for a total of 24 packages is obtained, and the number of defective packages /
Expressed in total. SO 4 post-cured at 175 ° C. for 4 hours
The same operation was performed on the P-type 16L package.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

According to the epoxy resin composition of the present invention, the amount of hydrogen gas generated when heated is 20 g per 1.0 g of the total resin composition.
Since it is less than nanomolar, the ferroelectric memory encapsulated by this has excellent ferroelectricity retention properties, and IC, LS
Widely applicable to the high reliability requirements of I.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31

Claims (4)

[Claims] 1. A method comprising: (A) an epoxy resin, (B) a phenolic resin curing agent, (C) an inorganic filler, (D) a curing accelerator, and (E) a non-organic silicon compound-based low stress agent, and an organic silicon compound. One or more selected components are used as essential components, and 175 ° C, 90
An epoxy resin composition for encapsulating ferroelectric memory, wherein the amount of hydrogen gas generated during minute heating is 20 nmol or less per 1.0 g of the entire resin composition. 2. The method according to claim 1, wherein the amount of hydrogen gas generated when the non-organic silicon compound-based low stress agent or the organic silicon compound is heated at 175 ° C. for 90 minutes is 0.5 μmol or less per 1.0 g. Epoxy resin composition for ferroelectric memory encapsulation. 3. The composition according to claim 1, wherein the compounding amount of at least one selected from the group consisting of a non-organic silicon compound-based low stress agent and an organic silicon compound is 4.0% by weight or less in the total resin composition. 3. The epoxy resin composition for sealing a ferroelectric memory according to 2. 4. A ferroelectric memory device wherein a ferroelectric memory is encapsulated using the epoxy resin composition according to claim 1, 2 or 3.