JPH0730166B2 - Resin-sealed semiconductor device - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a resin-encapsulated semiconductor device.

[Technical background of the invention and its problems]

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

When encapsulating a heat-generating semiconductor device, an electronic component, etc. with an epoxy resin composition, it is necessary to effectively dissipate the heat generated inside, and therefore a highly heat-conductive epoxy resin composition for encapsulation. Things are needed. However, it has been difficult to obtain sufficient thermal conductivity with conventional epoxy resin compositions using silica as a filler.

[Object of the Invention]

An object of the present invention is to provide a resin-sealed semiconductor device sealed with an epoxy resin composition having high thermal conductivity.

[Outline of Invention]

In order to achieve the above object, the present inventor has conducted repeated research using silicon nitride as a filler, and as a result, only silicon nitride having a β-type crystal structure is used as a filler. It was found that a high thermal conductivity epoxy resin composition for encapsulation can be obtained when used, and the present invention has been completed.

That is, the present invention includes (a) an epoxy resin, (b) a curing agent having two or more phenolic hydroxyl groups in one molecule, (c) β-type silicon nitride, and (d) an organic phosphine compound. A resin-encapsulated semiconductor device in which a semiconductor device is encapsulated with an epoxy resin composition for use in a semiconductor device.

The epoxy resin is generally known and is not particularly limited. For example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, etc. glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, An epoxy resin having two or more epoxy groups in one molecule such as a halogenated epoxy resin can be mentioned. 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 is β which is one of α type and β type which is known as a crystal system of silicon nitride.
The effect is limited to silicon nitride having one type as the main type, and the effect of the present invention cannot be obtained with α-type silicon nitride. Industrially pure α
It is difficult to obtain crystal system of β-type and β-type, and generally α phase and β phase coexist.

If the proportion of β-type contained in the crystal is sufficiently larger than that of α-type, the β-type effect is obtained, and it can be substantially regarded as β-type silicon nitride. When the ratio of the β-type crystal system contained in the crystal is expressed as a β ratio, if the β ratio is 80% or more, it can be regarded as the β-type silicon nitride of the present invention. More preferred is silicon nitride having a β ratio of 90% or more.

In the present invention, β-type silicon nitride is preferably contained in the epoxy resin composition in an amount of 60% by weight or more. This is because if it is less than this, sufficient thermal conductivity cannot be obtained.

The average particle size is 1-100 as the particle size distribution of β-type silicon nitride.
A powder having a particle size of μm and a maximum particle size of 500 μm or less is preferable.

The characteristics of the epoxy resin composition can be further improved by treating β-type silicon nitride with a surface treatment agent such as a silane coupling agent.

Other fillers (silica, alumina, calcium carbonate, etc.) may be used in combination, but care must be taken so that the thermal conductivity of the composition does not drop significantly.

It is necessary to add a curing accelerator to the encapsulating epoxy resin composition of the present invention. The curing accelerator is useful for shortening the curing time and improving the properties of the cured product. In order to obtain a highly reliable resin-sealed semiconductor device, it is necessary to use an organic phosphine compound.

The organic phosphine compound has the formula: 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 include 1,2-bis (diphenylphosphino) ethane and bis (diphenylphosphino) methane. Of these, arylphosphine compounds are preferable, particularly triphenylphosphine, tritolylphosphine, 1,2-bis (diphenylphosphino) ethane,
Most preferred is bis (diphenylphosphino) methane and the like. These organic phosphine compounds may be used alone or in a mixture of two or more. The composition ratio of the organic phosphine compound 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.

In the encapsulating epoxy resin composition of the present invention, if necessary, other additives such as natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters or paraffins, etc. Mold release agent, chlorinated paraffin,
Flame retardants such as bromotoluene, hexabromobenzene and antimony trioxide, colorants such as carbon black, silane coupling agents and the like may be appropriately added and blended. A general method for preparing the above-mentioned encapsulating epoxy resin composition as a molding material is to sufficiently mix the raw material components selected in a predetermined composition ratio with, for example, a mixer, and then perform a melt mixing treatment with a hot roll, or An epoxy resin molding material can be easily obtained by adding a mixing treatment with a kneader or the like.

The resin-encapsulated semiconductor device of the present invention can be easily manufactured by encapsulating the semiconductor device using the encapsulating epoxy resin composition. The most common method of sealing is the low-pressure transfer molding method, but sealing by injection molding, compression molding, casting, etc. 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. Heating at 150 ° C. or higher is particularly desirable for curing.

Example of Invention

Examples 1 to 3 Cresol novolac type epoxy resin having an epoxy equivalent of 200 (epoxy resin A), brominated epoxy novarac resin having an epoxy equivalent of 290 (epoxy resin B), phenol novolac resin curing agent having a molecular weight of 700, and β ratio as a filler. 95% silicon nitride (β type silicon nitride [I]), 90% β rate silicon nitride (β type silicon nitride [II]), α rate 90% silicon nitride (α type silicon nitride [I]), α 70% silicon nitride (α-type silicon nitride [II]), crystalline silica powder, fused silica powder, triphenylphosphine curing accelerator, antimony trioxide, carnauba wax, carbon black, silane coupling agent (γ-glyce) Cidoxypropyltrimethoxysilane) was selected for the composition (parts by weight) shown in Table 1. Regarding the filler, the volume% and the weight% in the composition are added in the table so that they can be compared with each other.

Nine kinds of transfer molding materials including comparative examples were prepared by mixing these compositions with a mixer and kneading with a heating roll.

Using the above molding materials, power IC in a transfer molding machine
The (integrated circuit) was sealed with resin and the moldability was examined. The results are shown in Table 2. Transfer molding was performed by molding a molding material heated to 90 ° C. by a preheater at 180 ° C. for 3 minutes.

◯: A resin-sealed semiconductor device was obtained.

X: The fluidity of the molding material was poor, and the cavity could not be filled, so that the resin could not be sealed.

As shown in Table 2, the composition of α-type crystalline silicon nitride and silica containing 73% by volume of the filler had poor fluidity and could not be transfer-molded, so a molded product could not be obtained. With respect to the remaining 6 types, the thermal conductivity of the obtained molded body was measured. The results are shown in Table 3. The thermal conductivity was measured at room temperature (23 ° C) using the laser flash method.

Examples 4 and 5 Next, as shown in Table 4, Examples 4 and 5 were prepared by using the same raw materials as in Examples 1 to 3, and in addition to the above raw materials, alumina powder as a filler and 1.8- as a curing accelerator. Diaza
Comparative Examples 7 to 17 were prepared using bicyclo (5,4,0) undecene-7 (DBU) and Curezol CN (trade name of imidazole manufactured by Shikoku Chemicals Co., Ltd.). These compositions were mixed with a mixer and kneaded with a roll in the same manner as in Examples 1 to 3 to prepare transfer molding materials.

When the moldability of the above-mentioned molding material was examined by the same method as in Examples 1 to 3, all molding was possible.

Next, the thermal conductivity of the molded body was measured by the same method as in Examples 1 to 3. The results are shown in Table 5.

Furthermore, in order to investigate the reliability of the semiconductor devices encapsulated with the resin compositions of Examples 1-5 and Comparative Examples 1-17, the thermal conductivity was 50%.
The evaluation test described below was conducted using a resin composition having a temperature of × 10 ^-4 cal / cms ° C or higher.

(1) Heat Cycle Test This test is performed to evaluate the reliability when the resin-encapsulated semiconductor device is repeatedly exposed to high temperature and low temperature. 20
Two constant temperature baths of 0 ° C. and −65 ° C. were prepared, and 20 resin-sealed semiconductor devices each were placed in a constant temperature bath of −65 ° C. and left for 30 minutes. Then take it out and leave it at room temperature for 5 minutes, then 200
After being placed in a constant temperature bath at 30 ° C. for 30 minutes, it was left again at room temperature 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 result is No. 6
Shown in the table.

(2) Pressure cooker test (PCT) This test is performed to evaluate the moisture resistance of the resin-sealed semiconductor device. 20 pieces of each of the resin-encapsulated semiconductor devices were left in saturated steam at 121 ° C. and 2 atm, and a moisture resistance test was conducted to examine a failure in which the aluminum wiring of the element was corroded by moisture and disconnected. The result is shown in the 7th vote.

[Advantages of the Invention] As described above in detail, according to the present invention, the thermal conductivity is 80 ×.
An epoxy resin composition for encapsulation of 10 ⁻⁴ cal / cm s ° C. or higher can be obtained, and a resin encapsulation type semiconductor device using the same can be provided. Further, the resin-encapsulated semiconductor device of the present invention has excellent reliability in a heat cycle test and a moisture resistance test, and its industrial value is great.

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Claims (6)

[Claims] 1. An epoxy resin composition in which a semiconductor device contains (a) an epoxy resin, (b) a curing agent having two or more phenolic hydroxyl groups in one molecule, and (c) β-type silicon nitride (d) an organic phosphine compound. A resin-encapsulated semiconductor device, which is encapsulated with a cured product. 2. The epoxy resin has an epoxy equivalent of 170 to 300.
Novolak type epoxy resin according to claim 1
Item 7. A resin-encapsulated semiconductor device according to item. 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-sealed semiconductor device according to claim 1, wherein the composition contains the β-type silicon nitride in an amount of 60% by weight or more. 6. The β-type silicon nitride has an average particle size of 1 to 100 μm.
The resin-encapsulated semiconductor device according to claim 1, which is a powder of m.