JPH0749465B2 - Resin-sealed semiconductor device - Google Patents

Description

The present invention relates to a resin-encapsulated semiconductor device using an epoxy resin composition, and particularly to an epoxy resin composition having high thermal conductivity and high reliability. The present invention relates to a resin-sealed semiconductor device using.

(Prior Art) Epoxy resin compositions are widely used for encapsulating semiconductor devices such as integrated circuits (ICs), large-scale integrated circuits (LSIs), transistors, electronic parts and other parts.

When a heat-generating semiconductor device, an electronic component, or the like is sealed with an epoxy resin composition, it is necessary to effectively dissipate the heat generated inside to the outside. Therefore, a highly heat-conductive epoxy resin for sealing. A composition is sought. In particular, recently, a sealing resin having a thermal conductivity of more than 100 × 10 ⁻⁴ cal / cmS ° C. has been required with the increase in capacity and integration of semiconductor elements. The sealing resin had a limit of 60 × 10 ^-4 cal / cmS ° C.

A technique of using silicon nitride, which has a higher thermal conductivity than silica, as a filler for epoxy resin is known (Japanese Patent Laid-Open No. 58-76).
456, JP-A-61-101522, etc.), it has been difficult to raise the thermal conductivity of the resin composition to 100 × 10 ⁻⁴ cal / cmS ° C. or higher by the conventionally known technique.

Further, in terms of reliability, the conventional resin composition using silicon nitride is insufficient, and improvement is required. The main problem with reliability is that the thin bonding wires that connect the resin-sealed semiconductor device elements and leads are repeatedly exposed to high and low temperatures and are cut by the stress of the sealing resin ( (Heat-resistant cycle characteristics) and aluminum electrodes on the surface of the element are corroded by moisture that has penetrated through the sealing resin in a high temperature and high humidity atmosphere (moisture resistance).

(Problems to be Solved by the Invention) The conventional epoxy resin composition has a problem that thermal conductivity is not sufficiently high and reliability such as heat cycle characteristics and moisture resistance is poor.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin-encapsulated semiconductor device using an epoxy resin composition having high thermal conductivity and high reliability.

[Structure of Invention]

(Means for Solving the Problems) As a result of various studies to achieve the above object, as a filler, a silicon nitride powder having a β-type crystal structure having a specific particle size distribution was used, and further, organic phosphine and / or It was found that a resin-encapsulated semiconductor device using an epoxy resin composition having high thermal conductivity and high reliability can be obtained only when organic phosphine oxide is used.

That is, the present invention provides a semiconductor device having (a) an epoxy resin, (b) a curing agent having two or more phenolic hydroxyl groups in one molecule, (c) 50% by weight or less of particles having a particle size of 15 μm or less, and 20 wt% or less of particles having a diameter of 200 μm or more and a weight average particle diameter of 15 to 100 μm, which is sealed with an epoxy resin composition containing β-type silicon nitride powder and (d) an organic phosphine and / or an organic phosphine oxide This is a resin-sealed semiconductor device characterized by the above.

The epoxy resin is generally known and is not particularly limited. For example, glycidyl ether type epoxy resin such as bisphenol A type epoxy resin and phenol novolac type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin Examples thereof include epoxy resins having two or more epoxy groups in one molecule such as herogenated epoxy resin. However, these epoxy resins may be used alone or in a mixture of two or more. A more preferable epoxy resin is a novolac type epoxy resin having an epoxy equivalent of 170 to 300, and examples thereof include a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, and a halogenated phenol novolac type epoxy resin. These epoxy resins preferably have a chlorine ion content of 10 ppm or less and a hydrolyzable chlorine content of 0.1% by weight or less.
The reason is that chlorine ion exceeding 10 ppm or 0.1% by weight
This is because if the amount of hydrolyzable chlorine exceeds the range, the aluminum electrode of the sealed semiconductor element is likely to be corroded.

The curing agent having two or more phenolic hydroxyl groups in one molecule used in the present invention is a phenol resin, polyoxystyrene, a phenol aralkyl resin and a polyhydric phenol compound, and specific examples thereof include phenol novolac. Resin, cresol novolac resin,
Examples thereof include tert-butylphenol novolac resin, nonylphenol novolac resin and other novolac type phenol resins, resol type phenol resin, polyparastyrene and other polyoxystyrenes, bisphenol A and the like, and halides of these compounds. Among these, novolac type phenol resin, phenol aralkyl resin and polyoxystyrene are most preferable. These curing agents can be used alone or in a mixture of two or more.

Regarding the compounding ratio of the epoxy resin and the curing agent, the ratio of the number of phenolic hydroxyl groups of the curing agent to the number of epoxy groups of the epoxy resin (number of phenolic hydroxyl groups / number of epoxy groups) is 0.5 to
It is desirable to formulate it so that it is within the range of 1.5. The reason is that if it is out of the above range, the reaction does not sufficiently occur, and the characteristics of the cured product are likely to deteriorate.

The silicon nitride used in the present invention contains 50% by weight or less of particles having a particle size of 15 μm or less and 20% of particles having a particle size of 200 μm or more.
It is a β-type silicon nitride powder having a weight average particle diameter of 15 to 100 μm in an amount of not more than wt%.

If the content of particles having a particle size of 15 μm or less exceeds 50% by weight, or if the weight average particle size is less than 15 μm, the thermal conductivity, electrical characteristics and reliability of the epoxy resin composition decrease.
There are drawbacks such as poor fluidity and poor filling, and sufficient characteristics cannot be obtained. 20 particles with a particle size of 200 μm or more
When the content exceeds 100% by weight, or when the weight average particle size exceeds 100 μm, the thermal conductivity, electrical characteristics and reliability of the epoxy resin composition deteriorate, molding defects due to gate clogging occur in transfer molding, and fillability. There are drawbacks such as poor quality, and sufficient characteristics cannot be obtained.

The α-type and β-type are known as the crystal structure of silicon nitride, but those used in the present invention are limited to the β-type, and the α-type cannot sufficiently obtain the effect of the present invention.

Industrially, it is difficult to obtain pure α-type and β-type crystals, and α-phase and β-phase are generally mixed, but if the ratio of β-type is sufficiently larger than that of α-type, The effect of the mold is obtained,
It can be substantially regarded as β type. If the β-type crystal content is expressed as β-type crystal, it can be regarded as the β-type silicon nitride of the present invention if the β rate is 80% or more. More preferred is silicon nitride having a β ratio of 90% or more.

By treating the silicon nitride powder with a silane coupling agent or other surface treatment agent, the filling property of the epoxy resin can be improved and the properties of the obtained epoxy resin composition can be improved.

Other fillers such as fused silica, crystalline silica, glass fiber, talc, alumina, calcium silicate, calcium carbonate, barium sulfate and magnesia may be added and blended. Of these, fused silica and crystalline silica are preferred because they have high purity and a small coefficient of thermal expansion.

In the present invention, an organic phosphine and / or an organic phosphine oxide is used as a curing accelerator. The organic phosphine has the formula [I] A third phosphine compound in which R _{1 to} R ₃ are all organic groups, a second phosphine compound in which only R ₃ is hydrogen, R ₂ , R ₃
There is a first phosphine compound in which both are hydrogen. Specific examples include triphenylphosphine, tributylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, butylphenylphosphine, diphenylphosphine, phenylphosphine and octylphosphine. Further, R ₁ may be an organic group containing an organic phosphine. Examples are 1,2-bis (diphenylphosphino) ethane, bis (diphenylphosphino) methane and the like.

Of these, arylphosphine compounds are preferred,
In particular, triphenylphosphine, 1,2-bis (diphenylphosphino) ethane, bis (diphenylphosphino) methane and the like are most preferable. Further, these organic phosphines may be used alone or in a mixed system of two or more kinds. The content of the organic phosphine may be generally in the range of 0.01 to 20% by weight of the resin component (epoxy resin and curing agent), but particularly preferable properties are obtained in the range of 0.01 to 5% by weight.

The organic phosphine oxide has the formula [II] In the above, R ₁ is selected from organic groups, and R ₂ and R ₃ are compounds selected from organic groups or hydrogen. The organic group is a general term for a hydrocarbon group such as an alkyl group, an aryl group, a cycloalkyl group, an alkaryl group and an aralkyl group, and their derivatives.

A specific example is triphenylphosphine oxide,
Tris (methylphenyl) phosphine oxide, tribenzylphosphine oxide, trioctylphosphine oxide, tricyclohexylphosphine oxide, diphenylethylphosphine oxide, phenyldimethylphosphine oxide, diphenylphosphine oxide, dihexylphosphine oxide, phenylphosphine oxide, heptadecylphosphine oxide, Tris (chlorophenyl) phosphine oxide, bromophenyldiphenylphosphine oxide, tris (hydroxyphenyl) phosphine oxide, tris (methoxyphenyl)
Examples include phosphine oxide. The content of the organic phosphine oxide is preferably 0.01 to 20% by weight of the resin. The organic phosphine and the organic phosphine oxide may be used alone or in combination.

If necessary, the epoxy resin composition used in the present invention may further contain other additives such as natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters or paraffins. Mold agent, chlorinated paraffin,
Flame retardants such as bromotoluene, hexaprobenzene, and animonium trioxide, pigments or dyes such as carbon black titanium oxide, and the like may be appropriately added and blended. A general method for preparing the above-mentioned epoxy resin composition as a molding material is to thoroughly mix the raw material components selected in a predetermined composition ratio with, for example, a mixer, and then perform a melt mixing process with a hot roll, or a mixing with a kneader or the like. An epoxy resin molding material can be easily obtained by adding a treatment.

The resin-encapsulated semiconductor device of the present invention can be easily manufactured by encapsulating the semiconductor device with the epoxy resin composition. The most common sealing method is a low-pressure transfer molding method, but sealing by injection molding, compression molding, casting or the like is also possible. The epoxy resin composition is heated and cured during encapsulation, and finally a resin-encapsulated semiconductor device encapsulated with the cured product of this composition can be obtained. 150 ° C for curing
It is desirable to heat above.

(Working) Beta-type silicon nitride powder used in the present invention is 50% by weight or less of particles having a particle size of 15 μm or less, 20% by weight or less of particles having a particle size of 200 μm or more, and β-type silicon nitride powder having a weight average particle size of 15 to 100 μm is an epoxy resin. It is possible to obtain an epoxy resin composition having a good filling property with respect to, a high density filling without impairing the fluidity, and a high thermal conductivity. For example, the thermal conductivity of the composition of the present invention is nearly twice as high as that of the epoxy resin composition prepared by using the silicon nitride powder having a weight average particle diameter of 7 to 10 μm as a filler and prepared under the same conditions as the present invention. . Thus, when the silicon nitride powder is used as the filler of the epoxy resin composition, the thermal conductivity can be remarkably improved by slightly changing the fineness distribution of the powder, and the range defined by the present invention is particularly preferable. Giving thermal conductivity has never been known or predicted before.

Further, it has been found that when the above silicon nitride powder and organic phosphine and / or organic phosphine oxide are used in combination, reliability such as heat cycle characteristics and moisture resistance is remarkably improved. In contrast, silicon nitride and other catalysts (3rd
The above effect cannot be obtained even if a combination of amine, imidazole, etc.) or another filler (silica, alumina, etc.) and an organic phosphine and / or an organic phosphine oxide is combined.

It has not been known at all in the past that the reliability such as heat cycle characteristics is remarkably improved when the above silicon nitride powder is combined with organic phosphine and / or organic phosphine oxide, and it cannot be predicted from the prior art. It was

(Examples) Examples 1 to 5 Cursol novolac type epoxy resin having an epoxy equivalent of 200 (epoxy resin A), brominated bisphenol A type epoxy resin having an epoxy equivalent of 400 (epoxy resin B), and phenol novolac resin curing with a hydroxyl equivalent of 107. 30% by weight of particles having a β ratio of 95% and a particle size of 15 μm or less, 0.1% by weight of particles having a particle size of 200 μm or more, and a weight average particle size of 40 μm
Silicon nitride powder (silicon nitride A), 40% by weight of particles having a particle size of 15 μm or less, 5% by weight of particles having a particle size of 200 μm or more,
Silicon nitride powder (silicon nitride B) with a weight average particle size of 25 μm, 15% by weight of particles with a particle size of 15 μm or less, particle size of 200 μm
10% by weight of the above particles, silicon nitride powder (silicon nitride C) having a weight average particle size of 70 μm, 30% by weight of particles having a β ratio of 90% and a particle size of 15 μm or less, and 0.5% by weight of particles having a particle size of 200 μm or more ,
Silicon nitride powder (silicon nitride D) having a weight average particle diameter of 30 μm, crystalline silica powder having a weight average particle diameter of 20 μm, triphenylphosphine, triphenylphosphine oxide as a curing accelerator, antimony trioxide as a flame retardant, mold release Carnauba wax as an agent, carbon black as a colorant, and γ-glycidoxypropyltrimethoxysilane as a silane coupling agent were selected in the composition (parts by weight) shown in Table 1. Mixing these compositions with a mixer,
Five types of transfer molding materials were prepared by kneading with a heating roll.

Comparative Examples 1 to 12 In addition to the raw materials used in the examples, silicon nitride having a β ratio of 95% as a filler, a powder having a weight average particle diameter of 7 μm (silicon nitride E), and a powder having a weight average particle diameter of 150 μm ( Silicon nitride F),
70% by weight of particles with a particle size of 15 μm or less and powder (silicon nitride G), 40% by weight of particles with a particle size of 200 μm or more (silicon nitride H), and silicon nitride with an α ratio of 90% and particle size of 15 μm or less 30% by weight of particles, 0.1% by weight of particles having a particle size of 200 μm or more,
Weight average particle diameter 40μm powder (silicon nitride I), α ratio 70%
Powder of silicon nitride having a weight average particle size of 7 μm (silicon nitride J) Alumina powder having a weight average particle size of 20 μm, 1,8-diaza-bicyclo (5,4,0) undecene-7 as a curing accelerator
(DBU) and Curezol CN (trade name of imidazole manufactured by Shikoku Chemicals Co., Ltd.) were used to prepare 12 types of comparative examples shown in Table 1 in the same manner as in Examples to prepare transfer molding materials.

A disc having a thickness of 1 mm was molded using the epoxy resin compositions of the above Examples and Comparative Examples, and the thermal conductivity of the disc was measured. The thermal conductivity was determined by the laser flash method. The results obtained are shown in Table 2.

Further, the bipolar integrated circuits were resin-sealed by transfer molding using the molding materials of the above-mentioned examples and comparative examples. The sealing was performed by molding a molding material heated to 90 ° C. by a preheater at 180 ° C. for 2 minutes and then performing after-curing at 180 ° C. for 8 hours.

The resin-encapsulated semiconductor device thus obtained was subjected to a reliability test as described below.

(1) Thermal Cycle Test Two constant temperature baths of + 200 ° C. and −65 ° C. were prepared, and each of the 20 resin-encapsulated semiconductor devices was placed in a constant temperature bath of −65 ° C. and left for 30 minutes. Then, it was taken out and left at room temperature for 5 minutes, then put in a + 200 ° C. thermostat for 30 minutes and then left at room temperature again for 5 minutes. The above operation was set as one cycle, and the heat cycle test was continuously performed. The cycle was interrupted as needed in accordance with the progress of the thermal cycle test, the characteristics of the resin-sealed semiconductor device were measured using a tester, and the occurrence of failure was investigated. The results are shown in Table 2.

(2) Pressure cooker test (PCT) 121 ° C, 20 humidity each of the above resin-encapsulated semiconductor devices are left in saturated water vapor, the aluminum wiring of the element is corroded by moisture, and a moisture resistance test is conducted to check for failures. I went.
The results are shown in Table 3.

(3) Bias-Pressure Cooker Test (B-PCT) Each of the 20 resin-sealed semiconductor devices was placed in saturated steam at 121 ° C. and 2 atm, and a bias voltage of 15 V was applied to the aluminum wiring of the element due to moisture. A moisture resistance test was carried out to check for failures caused by corrosion and disconnection. The results are shown in Table 3.

〔The invention's effect〕

As described above in detail, the epoxy resin composition of the present invention and the resin-encapsulated semiconductor device using the same have high thermal conductivity and excellent reliability such as heat cycle characteristics and moisture resistance. And its industrial value is great.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C08L 63/00 NLD H01L 23/29 23/31

Claims (5)

[Claims] 1. A semiconductor device comprising (a) an epoxy resin, (b) a curing agent having two or more phenolic hydroxyl groups in one molecule, (c) 50% by weight or less of particles having a particle size of 15 μm or less, and a particle size of 20 wt% or less of particles of 200 μm or more and β-type silicon nitride powder having a weight average particle diameter of 15 to 100 μm and (d) an epoxy resin composition containing an organic phosphine and / or an organic phosphine oxide A resin-encapsulated semiconductor device comprising: 2. A resin-sealed semiconductor device according to claim 1, wherein the epoxy resin is a novolac type epoxy resin. 3. The resin-sealed semiconductor device according to claim 1, wherein the curing agent is a novolac type phenol resin. 4. The resin-sealed semiconductor device according to claim 1, wherein the β-type silicon nitride has a β ratio of 80% or more. 5. The resin-encapsulated semiconductor device according to claim 1, wherein the epoxy resin composition further contains fused silica and / or crystalline silica.