JPH11147938A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition having improved adhesion to a polyimide resin at high temperatures and enhanced adhesion to a microstructure or to a structure having an interface between materials of different kinds by forming a composition essentially consisting of an epoxy resin, a phenolic resin curing agent, a cure accelerator, and an inorganic filler, wherein the equivalent ratio of the total epoxy resin to the total phenolic resin curing agent is specified. SOLUTION: The epoxy resin comprises 20-70 wt.% epoxy resin represented by formula I (wherein R1 to R17 arc each H, a halogen, or a I-6C alkyl; the same shall apply hereinbelow), formula II and formula III and 30-80 wt.% epoxy resin represented by formula IV (wherein R18 is a halogen or a 1-6C alkyl; and (n) is 0-10). The equivalent ratio of the total epoxy resin to the phenolic resin curing agent should be 1.05-1.50. The phenolic resin curing agent used is a phenol novolac resin or the like. The cure accelerator used is exemplified by triphenylphosphine. The inorganic filler used is a fused silica powder, alumina, or the like.

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 reliability, in particular, adhesion to a polyimide resin on the surface of a semiconductor element, and a semiconductor device using the same.

[0002]

2. Description of the Related Art An epoxy resin composition for semiconductor encapsulation (hereinafter referred to as a resin composition) for encapsulating semiconductor elements such as transistors, capacitors, diodes, ICs, and LSIs comprises a thermosetting resin as a resin component. As a filler, it is composed of an inorganic filler and other various components, and is widely used as a material suitable for moldability, reliability, and mass productivity.
However, in recent years, electronic devices have become smaller, lighter, more sophisticated,
In the market trend of price reduction, requirements for resin compositions have become increasingly severe. In order to improve productivity, it is necessary to shorten the molding time and improve the yield, etc. Furthermore, the package is rapidly exposed to a high temperature of 200 ° C. or more in the solder immersion or reflow process due to the adoption of the surface mounting method. In addition, there is a problem with solder heat resistance that the package is cracked or the interface between the semiconductor element and the cured product of the resin composition is separated to lower the moisture resistance. Furthermore, in recent years, in semiconductor memories, which have been highly integrated, miniaturized circuits, and chips have become larger, the sliding of aluminum circuits due to the heat shrinkage of the sealing resin and the thermal shock during the soldering process, the inorganic passivation film on the chip surface (oxidation (Silicon etc.) has become a problem, and in order to solve these problems, coating of polyimide resin has been performed to protect the semiconductor element surface. There is a problem that the nature is not enough. In the package structure, high adhesion to different types of interfaces (polyimide resin, Ag plating, etc.) like the LOC (lead-on-chip) structure is required, but at present, sufficient characteristics are not obtained. It is.

In order to shorten the molding time in order to improve the productivity, a method of improving the curability is generally used. However, the flow rate is reduced due to an increase in the rate of thickening, and the inside of the semiconductor device is reduced. Since the wettability between the semiconductor element and the lead frame and the resin composition is reduced, the adhesion is lowered. In particular, such a phenomenon is remarkable due to the step difference in the LOC structure, and the interface peeling is caused. Easy to solder heat resistance,
There is a problem in that the moisture resistance reliability is significantly reduced, and furthermore, the pressure loss on the internal element is increased due to the increase in the viscosity, thereby lowering the yield. In order to prevent such interface separation and improve solder heat resistance, use of heat-resistant epoxy resin, use of flexible resin to reduce stress during solder immersion, and use of highly reactive coupling agents to improve adhesiveness Numerous proposals have been made, such as adding an adhesion-imparting component, increasing the amount of an inorganic filler to reduce the coefficient of thermal expansion, etc., while improving the adhesion with a lead frame or a semiconductor element, and At present, there is no resin composition which can cope with the microstructure of various small, large, thin, and thick semiconductor devices and can also improve excellent fluidity and adhesion.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a semiconductor encapsulation which has improved adhesiveness to a polyimide resin at a high temperature and has improved adhesiveness to a fine structure or a structure having a heterogeneous interface by giving fluidity. The present invention provides an epoxy resin composition for use.

[0005]

According to the present invention, there is provided (A) at least one selected from the group consisting of epoxy resins represented by the general formulas (1), (2) and (3) by 20 to 70. weight%
And an epoxy resin containing 30 to 80% by weight of an epoxy resin represented by the general formula (4), (B) a phenol resin curing agent,
Equivalent ratio of the total epoxy resin to the total phenolic resin curing agent (the number of epoxy groups of the epoxy resin / the number of hydroxyl groups of the phenolic resin curing agent) of (C) a curing accelerator and (D) an inorganic filler as essential components = 1.05. To 1.50, which is an epoxy resin composition for semiconductor encapsulation.

[0006]

Embedded image (R ₁ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms, and may be the same or different.)

[0007]

Embedded image (R _{2 to} R ₉ each independently represent a hydrogen atom, a halogen atom, or a group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms. Are different from each other.)

[0008]

Embedded image (R _{10 to} R ₁₇ each independently represent a hydrogen atom, a halogen atom, or a group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms. The two aryl groups are the same as each other.)

[0009]

Embedded image (R ₁₈ represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 10.)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the polyimide of the present invention, the surface of which has been subjected to plasma treatment, the CN bond in the imide ring is preferentially cleaved, and the carboxyl group, amino group, etc. Functional groups are generated and present. Therefore, by setting the equivalent ratio of the total epoxy resin and the total phenol resin curing agent to be used (the number of epoxy groups of the epoxy resin / the number of hydroxyl groups of the phenol resin curing agent) to be 1.05 to 1.50, the epoxy resin that does not contribute to the crosslinked structure Is compatible with or reacts with functional groups such as carboxy groups and amino groups on the polyimide resin surface to give excellent adhesion. The biphenyl type epoxy resin represented by the general formula (1) and the stilbene type epoxy resin represented by the general formulas (2) and (3) have excellent fluidity due to low viscosity when melted. Further, by setting the equivalent ratio to 1.05 to 1.50, a synergistic effect that an epoxy resin that does not contribute to the crosslinked structure imparts fluidity and improves not only the polyimide resin but also the wettability with different interfaces such as metals. Give effect.
Further, by using at least one selected from the group of epoxy resins represented by the general formulas (1), (2) and (3) and the epoxy resin represented by the general formula (4),
Compared with the case where the general formula (1), the general formula (2) and the general formula (3) are used alone, the crosslink density becomes higher, the glass transition point becomes higher, and the adhesion at high temperatures is improved.

When the equivalent ratio exceeds 1.50, a sufficient crosslinked structure cannot be obtained, so that the curability is greatly reduced, and a problem is caused in the moldability. On the other hand, if the equivalent ratio is less than 1.05, the amount of the epoxy resin that does not contribute to the crosslinked structure becomes extremely small, so that it becomes difficult to bleed on the surface of the polyimide resin on the semiconductor element which becomes larger, and it is not possible to obtain sufficient adhesion. . The epoxy resin used in the present invention comprises at least one selected from the group consisting of the epoxy resins represented by the general formulas (1), (2) and (3) in an amount of 20 to 70% by weight and the general formula and the general formula It is composed of 30 to 80% by weight of the epoxy resin represented by the formula (4). When the amount of the epoxy resin represented by the general formula (4) exceeds 80% by weight, it is not possible to obtain curability that does not cause a problem in moldability. Although it can be done, the elastic modulus is greatly increased, so that for those with steps such as LOC structure, sufficient adhesion between different types of interfaces cannot be obtained, and the fluidity also decreases. Therefore, the thin package cannot be filled. When the epoxy resin represented by the general formula (4) is 2
If it is less than 0% by weight, improvement in high-temperature adhesion due to high crosslinking density cannot be obtained.

In the biphenyl type epoxy resin represented by the general formula (1), R ₁ is a hydrogen atom, a methyl group,
Examples thereof include an ethyl group, a propyl group, a butyl group, an amyl group, a chlorine atom and a bromine atom, and among them, a methyl group is more preferable. In the stilbene type epoxy resins represented by the general formulas (2) and (3), the substituents R _{2 to} R ₁₇ are, for example, methyl, ethyl, propyl, butyl, amyl, hexyl, respectively. Groups (including isomers), a cyclohexyl group, a chlorine atom and a bromine atom. Among these, a methyl group, an ethyl group, a propyl group and a butyl group are more preferable from the viewpoint of low melt viscosity of the resin. It is more preferable to use the stilbene type epoxy resin of the general formula (2) alone and the stilbene type epoxy resin of the general formula (3) in combination with the stilbene type epoxy resin of the general formula (2). The stilbene-type epoxy resins of the general formulas (2) and (3) each have various structures depending on the type of the substituent, and each stilbene-type epoxy resin has a single structure and two or more types. May be used as a mixture having the following structure.

In the case where the stilbene type epoxy resin of the general formula (2) and the stilbene type epoxy resin of the general formula (3) are mixed and used, if the melting point is lowered by mixing both resins, the mixing method is as follows. There is no particular limitation. 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. 1
There is no particular problem if the temperature is adjusted to 50 ° C. In the novolak-type epoxy resin represented by the general formula (4), R ₁₈ includes a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a chlorine atom and a bromine atom. A methyl group is more preferred.

The phenolic resin used in the present invention comprises 1
It refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in the molecule, and known ones can be used. For example, phenol novolak resin, cresol novolak resin, balaxylylene-modified phenol resin, meta-xylylene / para-xylylene-modified phenol resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin and the like can be mentioned. These resins may be used alone or as a mixture. The curing accelerator used in the present invention may be any one that promotes the reaction between the epoxy resin and the phenolic hydroxyl group,
What is generally used for a sealing material can be widely used, for example, 1,8-diazabicyclo (5,4,
0) Undecene-7, triphenylphosphine, tetraphenylphosphonium / tetraphenylborate, 2-
Methylimidazole and the like may be used alone or in combination. As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder,
Porous silica powder, silica powder crushed secondary aggregated silica powder or porous silica powder, alumina and the like,
Particularly, a fused silica powder is preferable.

The epoxy resin composition of the present invention comprises (A)
(D) is an essential component, but if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony oxide, hexabromobenzene, a coloring agent such as carbon black and red iron, and a silicone oil Various additives such as a low-stress additive such as rubber and a release agent may be appropriately compounded. In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, (A)
After thoroughly mixing the components (D) and other additives with a mixer or the like, the mixture is further melt-mixed with a hot roll or a kneader or the like, cooled, and ground to form a molding material. In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor using the epoxy resin composition of the present invention, it is only necessary to cure and mold by a conventional molding method such as transfer molding, compression molding and injection molding.

[0016]

The present invention will be described below by way of examples. The mixing ratio is by weight. Example 1 The following composition: Biphenyl type epoxy resin (YX4000HK, epoxy equivalent: 195, manufactured by Yuka Shell Epoxy Co., Ltd.) 4.1 parts by weight Orthocresol novolac type epoxy resin (EOCN1 020-55 manufactured by Nippon Kayaku Co., Ltd.) 2.2 parts by weight para-xylylene-modified phenol resin (manufactured by Mitsui Chemicals, Inc., XL-225LL, hydroxyl equivalent 174) 5.5 parts by weight fused silica 85.0 parts by weight brominated epoxy resin (epoxy equivalent 359) 0.5 parts by weight Triphenylphosphine 0.3 parts by weight Antimony trioxide 1.3 parts by weight Silane coupling agent 0.5 parts by weight Carnauba wax 0.3 parts by weight Carbon black 0.3 parts by weight Mixer at room temperature And mixed at 50-130 ° C for 2 hours.
The mixture was kneaded with a shaft roll, cooled and pulverized to obtain a molding material, which was tabletted to obtain an epoxy resin composition for semiconductor encapsulation. This composition was molded using a low-pressure transfer molding machine (molding conditions: 175 ° C., 70 kg / cm ² , 120 seconds), and the obtained molded article was post-cured at 175 ° C. for 8 hours and evaluated. Table 1 shows the results. << Evaluation Method >> Spiral flow: Using a mold for measuring spiral flow according to EMMI-I-66, using a mold temperature of 175 ° C.
The measurement was performed at an injection pressure of 70 kg / cm ² and a curing time of 2 minutes.
Spiral flow is a parameter of fluidity, and the larger the value, the better the fluidity. Unit: cm Curing torque: Curast meter (Orientec,
175 using JSR Curastometer IVPS type
After 90 seconds, the torque was measured. The torque in the curast meter is a parameter of curability, and the larger the numerical value, the better the curability. Unit: kgf-cm Adhesion: A semiconductor element having a polyimide resin film on the surface is adhered to an 80pQFP (1.5 mm thick) type lead frame (the tip of the inner lead is covered with silver plating), and then the above resin composition is used. A cured product was obtained by curing at 175 ° C. for 2 minutes to obtain a sample by post-curing at 175 ° C. for 8 hours. Six packages were obtained for each material. This package was placed in a constant temperature / humidity chamber at 85 ° C. and 85% for 168 hours, and then subjected to IR reflow treatment at 240 ° C. Observe the peeling of the polyimide resin film surface on the surface of the semiconductor element inside the package, the silver plating surface on the tip of the inner lead and the back surface of the pad (back surface of the lead frame) with an ultrasonic flaw detector, and cure each surface and the resin composition. And the ratio of the peeled area was measured. Peeling rate ((peeled area) / (area of each surface) × 10)
0) was expressed in%.

Examples 2 to 10 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Example 7
Epoxy resin A used in Comparative Examples 3 and 4 was 4,
4'-bis (2,3'-epoxypropoxy) -5'-
40% by weight of a resin containing tertiary butyl-2,3 ', 5'-trimethylstilbene as a main component and 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5 '
A mixture of 60% by weight of a resin mainly composed of tetramethylstilbene (epoxy equivalent: 209). 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.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the present invention, it is possible to obtain an epoxy resin composition for semiconductor encapsulation having a structure having a heterogeneous interface and high adhesion to a polyimide resin at a high temperature. It can respond to reliability.

Claims (2)

[Claims] 1. (A) 20 to 70% by weight of at least one selected from the group of epoxy resins represented by the general formulas (1), (2) and (3) and the general formula (4) An epoxy resin containing 30 to 80% by weight of an epoxy resin represented by
(B) a phenolic resin curing agent, (C) a curing accelerator, and (D) an inorganic filler as essential components, and an equivalent ratio of all epoxy resins to all phenolic resin curing agents (the number of epoxy groups in the epoxy resin / the phenolic resin curing agent). Hydroxyl number) = 1.0
An epoxy resin composition for semiconductor encapsulation, which has a ratio of 5 to 1.50. Embedded image (R ₁ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms, and may be the same or different.) (R _{2 to} R ₉ each independently represent a hydrogen atom, a halogen atom, or a group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms. The two aryl groups are different from each other.) (R _{10 to} R ₁₇ each independently represent a hydrogen atom, a halogen atom, or a group or atom selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms. The two aryl groups are the same as each other.) (R ₁₈ represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, and n is an integer of 0 to 10.) 2. A semiconductor device comprising a semiconductor element having a polyimide resin film on its surface bonded to a lead frame, and then sealed with the epoxy resin composition according to claim 1.