JPH02261856A - Epoxy resin composition for semiconductor sealing and semiconductor device sealed therewith - Google Patents

Abstract

PURPOSE:To prepare an epoxy resin compsn. for semiconductor sealing having an excellent moldability and giving a cured product with an excellent resistance to thermal shock by compounding an epoxy resin, a phenolic resin curing agent, a curing accelerator, and a specific silica powder as essential components. CONSTITUTION:An epoxy resin [e.g. an epoxidized tri(hydroxyphenyl)methane], a phenolic resin curing agent (e.g. a phenol novolak resin), a curing accelerator (e.g. triphenylphosphine), and a silica powder contg. 40 to 65wt.% (based on the total compsn., the same applies hereunder) spherical silica powder with a mean particle diameter of 10 to 50mu, 5 to 35wt.% silica powder with a mean particle diameter of 2 to 10mu, and 25 to 35wt.% silica powder with a mean particle diameter of 0.1 to 2mu are compounded as essential components.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides an epoxy resin composition for semiconductor encapsulation that provides a cured product having excellent thermal shock resistance, and encapsulation using this resin composition. The present invention relates to a resin-sealed semiconductor device.

(Prior Art) Conventionally, as a resin composition for sealing a semiconductor device, an epoxy resin composition using a phenol novolak resin as a curing agent, which has excellent high-temperature electrical properties, moldability, etc., has been mainstream. However, in recent years, with the increasing integration of semiconductor devices,
The miniaturization of each functional unit on an element and the increase in the size of the element pellet itself are progressing rapidly. Due to these changes in element pellets, conventional sealing resin compositions are no longer able to satisfy the requirements for thermal shock resistance and the like.

That is, when a conventional sealing resin composition is used to seal a device pellet having a large size and a fine surface structure, phosphosilicate glass, which is a coating material for protecting the aluminum (Al2) pattern on the surface of the device pellet, is removed. (P.S.
G) Cracks may occur in the film or silicon nitride (SiN) film,
This may cause cracks in the element pellet or in the sealing resin. This tendency is particularly strong when a thermal cycle test is performed. As a result, the appearance of the semiconductor device is poor and the reliability is lowered.

As a countermeasure against these problems, for example, in order to reduce the stress on the internal inclusions of the sealing resin, a method has been taken in which the coefficient of thermal expansion of the resin composition is lowered by increasing the amount of filler. However, this method has a problem in that moldability is impaired because the use of a large amount of filler significantly increases the melt viscosity of the resin composition.

Furthermore, with the above-mentioned changes in the element pellet, a decrease in reliability, which is thought to be caused by local stress acting on the element pellet from the resin and filler, has become a problem.

In order to avoid this, it is considered effective to cut coarse particles having a crushed form and use a filler. In addition, if the package is small and thin, the gate of the molding die is narrower than normal ones, so in order to make it easier to inject the molten resin composition into the mold, it is necessary to fill it with crushed coarse particles. The presence of agent particles is undesirable. However, if the average particle size of the filler is made small based on these points of view, the excitation viscosity of the resin composition increases, which may lead to unfilling or deformation of the bonding wire.

Therefore, spherical fillers that cause less damage to the device and have good fluidity are attracting attention, but if only spherical fillers with relatively coarse particles are used, the breakage that occurs during molding becomes significantly longer. There are drawbacks.

(Problems to be Solved by the Invention) As mentioned above, conventional resin compositions for semiconductors do not have sufficient thermal shock resistance, and even if the thermal shock resistance is improved by adjusting the filler, the moldability will deteriorate. There was a problem.

The purpose of the present invention is to solve these problems and provide an epoxy resin composition for semiconductor encapsulation that has excellent thermal shock resistance and good moldability, and a resin-encapsulated semiconductor using this epoxy resin composition. The goal is to provide equipment.

[Structure of the Invention] (Means and Effects for Solving the Problems) The epoxy resin composition for semiconductor encapsulation of the present invention comprises (a) an epoxy resin, (b) a phenolic resin curing agent, (c) a curing accelerator, (d) In an epoxy resin composition for semiconductor encapsulation containing silica powder as an essential component, as the silica powder,
40 to B5% by weight of the entire composition of spherical silica powder with an average particle diameter of Ion or more and 501 or less, ■ an average particle diameter of 21 or more,
5 to 35% by weight of the entire composition,
(2) It is characterized by containing silica powder with an average particle diameter of 0.1 n or more and less than 2 μs in a proportion of 25 to 35% by weight of the entire composition.

The resin-sealed semiconductor device of the present invention is characterized in that a semiconductor chip is sealed with the epoxy resin composition.

In the present invention, the epoxy resin as component (a) is 1
Any compound containing at least two epoxy groups in the molecule may be used.

Examples of the epoxy resin include bisphenol A epoxy resins, novolak epoxy resins, alicyclic epoxy resins, glycidyl ester epoxy resins, and epoxidized products of tri- or tetra(hydroxyphenyl) alkanes. One or more of these may be used.

In the present invention, the phenolic resin curing agent which is the component (b) may be any one that is generally known as a curing agent for epoxy resins. Examples of the phenolic resin curing agent include phenolic resins containing at least two phenolic hydroxyl groups, such as phenol novolac resins, cresol novolac resins, and tri- or tetra(hydroxyphenyl) alkanes.

One or more of these may be used.

(b) The blending amount of the phenolic resin curing agent is usually (a)
The amount is 30 to 150 parts by weight per 100 parts by weight of the epoxy resin. If it is less than 30 parts by weight, the curing of the resin composition will be insufficient, and if it exceeds 150 parts by weight, the moisture resistance of the cured product will deteriorate. Preferably it is 50 to 100 parts by weight.

In the present invention, the curing accelerator which is component (c) may be any substance that is known to be used as a curing accelerator when curing an epoxy resin using a phenol resin. Good too.

Specific examples of curing accelerators include imidazole compounds such as 2-methylimidazole, 2-ethyl-4-methylimidazole, ■-cyanoethyl-2-ethylmethylimidazole, and 2-heptadecylimidazole; benzyldimethylamine, tris(dimethyl Tertiary amine compounds such as (aminomethyl) phenol; organic phosphine compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine; diazabicycloundecene or its salts, and the like. One or more of these may be used.

The amount of the curing accelerator (C) is usually 0.01 to 10 parts by weight per 100 parts by weight of the epoxy resin (a).

If the amount is less than 11 parts by weight, the resin composition will not be sufficiently cured, and if it exceeds 10 parts by weight, the moisture resistance of the cured product will deteriorate.

In the present invention, the silica powder as component (d) is as follows:
■ Spherical silica powder with an average particle diameter of 101 or more and 50 or less is 40 to 65% by weight of the entire composition, ■ Silica powder with an average particle diameter of 2 μm or more and less than 10 μm is 5 to 35% by weight of the entire composition, ■ Silica powder having an average particle diameter of 0.11 or more and less than 2n is contained in an amount of 25 to 35% by weight of the entire composition.

In the (d) component, the silica powder (■) has an average particle size of 10 to 50.
Any particle size may be used as long as the particle size is 8 m and the particles are spherical. ■
The silica powder may be any silica powder having an average particle diameter of 21 or more and less than 10 μm.

The silica powder (2) may be any silica powder having an average particle diameter of 0.11 or more and less than 21. These silica powders include, for example, crystalline silica powder, fused silica powder,
or a mixture thereof.

These silica powders have a ratio of ■40 to 65 to the entire composition.
It is blended at a blending ratio of heavy melon%, 05-35% by weight, and 025-35% by weight.

In component (d), as mentioned above, the spherical silica powder (①) is the main component. The average particle diameter of this spherical silica powder is 10 to 5.
The reason why it was set as 0% was because the average particle diameter of the main component, silica powder, was 50%.
If it exceeds 1, gate clogging is likely to occur during molding.
On the other hand, if the average particle diameter of the silica powder as the main component is less than 101, the melt viscosity of the resin composition becomes high. In order to prevent various operational difficulties such as gate clogging during molding, the maximum particle size is preferably 100 μm or less.

Furthermore, it is already known that the fluidity of a molten resin composition is increased by combining particles with a large particle size and ↑η particles with a small particle size (for example, J, Appl, Po1y +
merSej, 15.2007 (1971)). That is, by blending appropriate amounts of the silica component (1) and the silica component (2), the fluidity of the molten resin composition is greatly improved. For example, ■ with an average particle size of lO~501
For the spherical silica powder type 1 dish part, the average particle diameter is 0.1
When about 0.5 parts by weight of silica powder (1) with a diameter of 1 or more and less than 2 μm is added, the melt viscosity of the resin composition is lower than in the case of only (2). However, it is difficult to suppress the flakes that occur in the cured product using only the spherical silica powder (1) and the silica powder (2). In contrast, the present inventors have blended not only the spherical silica powder (1) and the silica powder (2) but also the silica powder (3) in the above proportions, without increasing the melt viscosity of the resin composition. It has been found that it is possible to shorten the par length that occurs during molding.

In the present invention, the silica powder as component (d) is blended in the resin composition at a ratio of 70 to 90% by weight in total. 70. i1! If it is less than fa%, the cured product will not exhibit sufficient thermal shock resistance. On the other hand, if it exceeds 90% by weight, the melt viscosity of the resin composition will increase and the moldability will decrease. As described above, in the epoxy resin composition of the present invention, even if the resin composition is highly filled with 80 to 90% silica powder using mold plates, the viscosity of the solution does not become high (very good). Shows moldability.

In addition to the above-mentioned components, the epoxy resin composition of the present invention may optionally contain coupling agents such as epoxysilane; mold release agents such as higher fatty acids and waxes; antimony, phosphorus compounds, and bromine. various thermoplastic resins such as polystyrene, polymethyl methacrylate, and polyvinyl acetate; stress-lowering agents such as silicone oil and silicone rubber; pigments such as carbon black; ion scavengers, etc. May be blended.

The epoxy resin composition of the present invention can be prepared by melt-kneading the above-mentioned components using a heated roll, kneader, or extruder, or by mixing them using a special mixer capable of pulverizing them, or by an appropriate combination of these methods. It can be manufactured into a variety of containers.

The resin-sealed semiconductor device of the present invention is manufactured by resin-sealing a semiconductor chip using the epoxy resin composition. In this case, low-pressure transfer molding is most commonly used, but sealing can also be achieved by injection molding, compression molding, casting, or the like. After-curing after sealing is preferably performed at a temperature of 150° C. or higher. Note that the semiconductor chip sealed with the epoxy resin composition of the present invention is not particularly limited.

(Example) Hereinafter, the present invention will be explained in more detail based on examples.

Examples 1 to 4 and Comparative Examples 1 to 4 As shown in Table 1, trifunctional epoxy resin (epoxidized product of tri(hydroxyphenyl)methane, epoxy equivalent 167, softening point 71.4°C), flame retardant epoxy Resin, phenol novolac resin (phenol per ff11OB
, softening point 78), triphenylphosphine as a curing accelerator, ester wax as a mold release agent, carbon black as a coloring agent, antimony dioxide as a flame retardant aid,
γ-glyndoxypropyltrimethoxysilane as a coupling agent, synthetic spherical silica (■) with an average particle size of 30 μm as a silica powder, synthetic spherical silica (■) with an average particle size of 5.4 us, and an average particle size of 6.11 The components of crushed silica (■) and synthetic microspherical silica (■) with an average particle size of 1.3 were mixed in the proportions shown in the table. At this time, the silica powder was first treated with a coupling agent in a Henschel mixer, and then the remaining components were added to the mixer and mixed.

Next, the mixture was kneaded with heated rolls at 60 to 110°C, cooled, and then pulverized to prepare epoxy resin compositions of Examples 1 to 4 and Comparative Examples 1 to 4.

The particle size distribution of the silica powder (■) is shown in FIG. 1, the particle size distribution of the silica powder (■) is shown in FIG. 2, and the particle size distribution of the silica powder (■) is shown in FIG. Further, for Examples 1 to 4, the particle size distribution of the silica powder mixtures ① to ② is shown in FIG. Also, the fourth
The particle size distribution shown in the figure is shown in FIG. 5 in logarithmic representation. As shown in FIG. 5, when the particle size distribution in FIG. 4 is expressed logarithmically, Examples 1 to 4 fall on almost the same curve.

Regarding the epoxy resin compositions of Examples 1 to 4 and Comparative Examples 1 to 4, various physical properties were measured, moldability was evaluated, and moisture resistance reliability was evaluated as shown in Table 2.

That is, each epoxy resin composition was melted and its melt viscosity was measured at 175°C using a Koka type flow tester. In addition, in order to evaluate the burr length during molding, the burr length produced in the 20ρ groove was measured using a burr measuring mold. Further, using a test piece molded at the same time, the bending elastic modulus was measured by a bending test, and the thermal expansion coefficient was measured.

Furthermore, each epoxy resin composition was used to seal a large semiconductor chip having a PSG layer on the surface by low pressure transfer molding. A thermal shock test (-65
Cold/hot cycle test with one cycle ranging from ℃ to 150℃)
The number of defects was investigated.

These results are shown in Table 2.

As is clear from Table 2, the epoxy resin compositions of Examples 1 to 4 have low melt viscosity and good fluidity, have short burst lengths in the cured products, and have excellent heat resistance. It can be seen that it exhibits impact resistance.

[Effects of the Invention] As detailed above, the epoxy resin composition of the present invention has good moldability, and the cured product thereof exhibits excellent thermal shock resistance. Therefore, the resin-sealed semiconductor device of the present invention has excellent reliability.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing particle size distributions of silica powders with different average particle diameters used in Examples of the present invention.
The figure shows the particle size distribution of the silica powder mixture used in Examples 1 to 4 of the present invention, and FIG. 5 is a diagram showing the particle size distribution of FIG. 4 in logarithmic representation. d = 30μ Tree child [ (μm) Figure 1

Claims (1)

[Scope of Claims] (1) An epoxy resin composition for semiconductor encapsulation containing (a) an epoxy resin, (b) a phenol resin curing agent, (c) a curing accelerator, and (d) silica powder as essential components, As the silica powder, (1) 40 to 65% by weight of spherical silica powder with an average particle diameter of 10 μm or more and 50 μm or less of the entire composition, (2) silica powder with an average particle diameter of 2 μm or more and less than 10 μm of the entire composition. (3) An epoxy resin composition for semiconductor encapsulation, characterized in that it contains silica powder with an average particle diameter of 0.1 μm or more and less than 2 μm in a proportion of 25 to 35% by weight of the entire composition. . (2) A resin-sealed semiconductor device, characterized in that a semiconductor chip is encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim (1).