JPH08208948A - Semiconductor device - Google Patents

Abstract

PURPOSE: To enable a large semiconductor device, etc., to be satisfactorily sealed and obtain a semiconductor device excellent in low-stress properties, stampability, moisture resistance, etc. CONSTITUTION: A semiconductor device is sealed with an epoxy resin compsn. contg. an epoxy resin, a curative, a silicone powder represented by the formula: (RSiO3/2 )n (wherein R is a monovalent org. group), and a silicone oil having at least one group selected from among epoxy, amino, hydroxyl, mercapto, and carboxyl groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable semiconductor device.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs, and LSIs are usually sealed in ceramic packages or plastic packages to form semiconductor devices. The ceramic package itself has high heat resistance and excellent moisture resistance, so it is resistant to temperature and humidity, and because it is a hollow package, it has high mechanical strength and highly reliable sealing. Is. However,
Recently, resin sealing using the above-mentioned plastic package has become the mainstream because the constituent materials are relatively expensive and there is a drawback that mass productivity is poor. An epoxy resin composition has been conventionally used for this type of resin encapsulation, and has achieved good results.

As the above-mentioned epoxy resin composition,
The o-cresol novolac epoxy resin, the phenol novolac resin as the curing agent, the tertiary amine compound as the curing accelerator, the fused silica as the inorganic filler, etc. It is prized for its excellent workability during transfer molding).

[0004]

However, the technological innovation in the semiconductor field is remarkable, and recently, with the improvement of the integration degree, the device size has been made larger and the wiring has been made finer, while the package shape has been made smaller and thinner. As the shape of the semiconductor device has been increasing, the encapsulating material for semiconductor elements is required to have lower stress, heat resistance, and moisture resistance than ever before. The conventional epoxy resin compositions for encapsulation are sufficiently excellent as encapsulation materials for semiconductor elements such as ICs and LSIs, but for example, encapsulation materials for large semiconductor devices having 8 pins or more, especially 16 pins or more. As a result, the shrinkage stress applied to the element tends to be too large, resulting in a decrease in thermal shock resistance and an increase in residual stress.

These drawbacks are noticeable especially when a cold heat test is performed. That is, when the conventional large-sized semiconductor device is subjected to a cooling / heating test, cracks are formed in the passivation film, which is a protective film for the encapsulating resin and the element, as a moisture entry path. As described above, an apparatus that causes cracks in the cold heat test is liable to cause cracks even in a normal use state, and various characteristics such as moisture resistance are inferior, and reliability as a semiconductor device is not sufficient.

For this reason, it has been proposed to add silicone oil to the encapsulating resin to reduce the stress. When silicone oil is added, a mark is displayed on the encapsulating resin portion of the obtained semiconductor device. In this case, there arises a problem that the imprintability is deteriorated.

The present invention has been made in view of such circumstances, and by using an epoxy resin composition having a special component composition for resin encapsulation, it is sufficiently compatible with encapsulation of large semiconductor devices and the like. It is an object of the present invention to provide a semiconductor device that can be manufactured and is excellent in characteristics such as low stress, imprintability, and moisture resistance.

[0008]

In order to achieve the above object, the semiconductor device of the present invention encapsulates a semiconductor element using an epoxy resin composition containing the following components (A) to (D). Take the configuration. (A) Epoxy resin. (B) Hardener. (C) A silicone powder represented by the following formula.

Embedded image (RSiO _3/2 ) _n [wherein R is a monovalent organic group. (D) A silicone oil having at least one functional group selected from the group consisting of an epoxy group, an amino group, a hydroxyl group, a mercapto group and a carboxyl group.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION That is, in order to improve the low stress property without impairing the imprintability of a semiconductor device, the present inventors have focused on a silicone-based material particularly used for an epoxy resin composition. As a result of repeated studies of
The inventors have found that the intended purpose can be achieved by using a silicone powder represented by _3/2 ) _n in combination with a specific silicone oil, and have reached the present invention.

The epoxy resin composition used in the present invention is
An epoxy resin (component A), a curing agent (component B), a silicone powder represented by the above general formula (component C), and a specific silicone oil (component D), which are usually obtained, It is in powder form or in tablet form.

Such an epoxy resin composition can be used as a plastic package excellent in low stress, imprintability and moisture resistance by using the above-mentioned C component, and realizes a highly reliable semiconductor device. It is possible.

The epoxy resin as the component A of the epoxy resin composition is not particularly limited as long as it is an epoxy compound having two or more epoxy groups in one molecule.
That is, various epoxy resins conventionally used as a sealing resin for semiconductor devices are suitable, and in addition, diglycidyl ether of bisphenol A and epibis type epoxy resin, bisphenol F type epoxy resin, and resorcin which are multimers thereof. Type epoxy resin, alicyclic epoxy resin and the like can also be used as suitable epoxy resins.

As the novolac type epoxy resin, those having an epoxy equivalent of 160 to 250 and a softening point of 50 to 130 ° C. are usually used. Among them, the cresol novolac type epoxy resin has an epoxy equivalent of 180 to 210 and a softening point of 60 to Those at 110 ° C are generally used. Also,
As the phenol novolac type epoxy resin, one having an epoxy equivalent of 160 to 200 ° C. and a softening point of 60 to 110 ° C. is generally used.

As the B component curing agent used together with the above-mentioned epoxy resin, novolac type phenol resin, acid anhydride or amine can be mentioned as suitable examples, and these can be used alone or in combination.

The novolac type phenolic resin is obtained by condensing phenols such as phenol, cresol, bisphenol A and aldehydes such as formaldehyde under acidic catalyst, phenol novolac resin, cresol novolac resin, bisphenol A.
Novolak resin and the like can be mentioned, and especially, the softening point is 50.
Those at ˜130 ° C. are preferable.

Examples of the acid anhydride include phthalic anhydride, maleic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, methylendomethylenetetrahydrophthalic anhydride, cyclohexane-1,2-dicarboxylic acid. Anhydrous, cyclohexane-
Examples thereof include ethylene glycol ester of 3,4-dicarboxylic acid anhydride and trimellitic acid anhydride.

As the amine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,4-bis (β)
-Amino-1-butyl) toluene, bis (p-β-amino-1-butylphenyl) ether, bis (p-β-methyl-o-aminophenyl) benzene, 1,3-diamino-4-isopropylbenzene , M-xylylenediamine, p-xylylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, bis (4-aminocyclohexyl) methane, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylene. Diamine, octamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3
-Methylheptamethylenediamine, 1,4-cyclohexanediamine and the like can be mentioned.

The silicone powder of component C used in this invention, linear polymers conventionally known silicone rubber or a rubber-like, yet unlike silicone compounds such as silicone oil, the general formula (RSiO _{3 / 2} ) It is a powder of organopolysiloxane having a dense three-dimensional network structure as indicated by _n . That is, this silicone powder has, for example, the following structure, and the portion surrounded by the dotted line is a repeating unit.

[0019]

Embedded image

Since the smaller the particle size of the silicone powder, the more preferable the effect on the reduction of thermal shock resistance and the residual stress, the particle size of at least 200 μm or less is preferably used from this viewpoint. . In particular, this can be said from the viewpoint of problems such as gate clogging when the epoxy resin composition of the present invention is used for transfer molding, and the smaller the particle size, the better.

Further, it is preferable that the particle shape of the silicone powder is spherical because it has a better dispersibility and is more effective in reducing the thermal shock resistance and the residual stress of the semiconductor device.

In the above formula of silicone powder, R is a monovalent organic group as already described,
Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, butyl group and cycloalkyl group,
One having an alkenyl group such as vinyl group, allyl group, aryl group such as phenyl group, xylyl group, aralkyl group such as phenylethyl group, or epoxy group, amino group, hydroxyl group, carboxyl group, carboxylic ester group or mercapto group Valuable organic substituents may be mentioned.

The silicone powder used in this invention is
It may be a homopolymer in which R is only one of the above organic groups, or a copolymer in which R is two or more of the above organic substituents.

The component D silicone oil used in the present invention has a function as a resin type modifier such as an epoxy resin and a curing agent, and contains an epoxy group, an amino group, a hydroxyl group, a mercapto group and a carboxyl group. It is composed of a silicone oil having at least one functional group selected from the group consisting of groups. This oil may be used alone or in combination of several kinds. The chemical structure of the portion other than the functional group is preferably polydimethylsiloxane, but a part thereof may be substituted with a phenyl group instead of the methyl group.

The above-mentioned functional group may be bonded to the end of the silicone molecule or may be bonded as a side chain.

The molecular weight of such silicone oil is
It is preferably 100 or more and 100,000 or less. That is, when the molecular weight is less than 100, the silicone molecule acts as a plasticizer for the skeleton of the cured resin to lower the reliability of the semiconductor device. On the contrary, when the molecular weight exceeds 100,000, the silicone molecule has an affinity for the resin system. It does not show the property, it becomes difficult to chemically react with the resin system, that is, it becomes difficult to modify,
The effect of the present invention is reduced.

The equivalent weight per functional group is 100 or more and 1
It is preferably 00000 or less. This is for the same reason as above.

The silicone oil of the present invention is preferably reacted with at least one of the epoxy resin as the component A and the curing agent as the component B, and then mixed with other raw materials.

Further, in the present invention, other raw materials such as a curing accelerator, a filler and a release agent can be used in addition to the components A, B, C and D as required. As the curing accelerator, any that serves as a catalyst for the curing reaction of the phenol-cured epoxy resin can be used, and examples thereof include 2,4,6-tri (dimethylaminomethyl) phenol, 2-methylimidazole and triphenylphosphine. Can be raised. As the filler, quartz glass powder, silica stone powder, talc, etc. can be used. As the release agent, conventionally known long-chain carboxylic acids such as stearic acid and palmitic acid, metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, carnauba wax and ester waxes can be used. .

The epoxy resin composition used in the present invention is
For example, when a novolac type phenol resin or an acid anhydride is used as the curing accelerator which is the component B, it can be manufactured as follows. That is, first, at least one of the epoxy resin (component A) and the curing agent (component B) is modified with silicone oil (component D), and the modified product and silicone powder (component C) and, if necessary, a curing accelerator, Mix other materials such as mold release agent and filler,
It can be produced by kneading at 80 to 120 ° C. for several minutes. When a curing accelerator is used, the addition amount thereof is usually adjusted so that the gelling time of the obtained epoxy resin composition at 150 ° C. is 30 to 90 seconds. On the other hand, when an amine-based curing agent is used as the curing agent, it is preferable that the silicone powder is melt-kneaded with the epoxy resin or the curing agent in advance and then finely pulverized to dry-blend all the components.

In the present invention, the above curing agent (component B)
Is contained in an amount sufficient to cure the epoxy resin (component A), that is, 0.4 to 2.0 equivalents, preferably 0.6 to 1.5, per 1 epoxy equivalent of the epoxy resin. It is preferable to use an equivalent amount. More specifically, when a novolac type phenol resin is used as a curing agent with respect to 1 epoxy equivalent of the epoxy resin, 0.5 to 2.0 equivalents, preferably 0.8 to 1.5 equivalents, Further, when an acid anhydride is used as the curing agent, it is 0.
4 to 1.2 equivalents, preferably 0.6 to 1.0 equivalents, and 0.5 to 2.0 when amine is used as a curing agent.
It is desirable that the amount is equivalent, preferably 0.8 to 1.5 equivalent.

Further, the content of the silicone powder (component C) is 2% by weight (hereinafter abbreviated as "%") or more based on the whole epoxy resin composition, and the addition amount including the inorganic component is 80% or less. It is preferable that That is, 2%
If it is less than the above range, a large amount of silicone oil must be added in order to improve the low stress property, and the imprintability of the obtained semiconductor device deteriorates. If the total amount of silicone powder and inorganic components exceeds 80%, the encapsulating resin composition will have problems in dispersibility and fluidity, and the resulting semiconductor device will be defective because the encapsulating resin is not filled. Is.

Further, the content of silicone oil (D component) is 15% or less with respect to the epoxy resin composition (A component + B component + C component + D component) excluding additional components such as curing accelerators and fillers. Preferably. This is because if it exceeds 15%, a problem tends to occur in the imprintability of the obtained semiconductor device.

The encapsulation of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be carried out by a usual method, for example, a known molding method such as transfer molding.

The semiconductor device thus obtained has extremely low stress, imprintability and moisture resistance.

[0036]

As described above, the semiconductor device of the present invention is sealed with a special epoxy resin composition containing silicone powder (component C) and silicone oil (component D). Since the plastic package is different from the one made of the conventional epoxy resin composition, the stress reduction is realized while the sealability is secured, the moisture resistance is excellent, and the reliability is high. In particular, by encapsulating with the above-mentioned special epoxy resin composition, it is possible to sufficiently cope with encapsulation of VLSI and the like, and to obtain the above high reliability in a large-sized semiconductor device having an element size of 16 mm ² or more. This is the greatest feature.

Next, examples will be described together with comparative examples.

First, an epoxy resin composition was prepared as follows.

[0039]

Example 1 In a separable flask equipped with a stirrer, o-cresol novolac epoxy resin (epoxy equivalent 220,
56 parts by weight (hereinafter abbreviated as “part”) of which the softening point is 80 ° C.) is melted by heating, and 15 parts of aminopropylpolydimethylsiloxane (amine equivalent: 10,000) at both ends is added to this, and 1
The mixture was stirred and mixed at 70 ° C. for 4 hours. The total amount of the obtained modified product and phenol novolac epoxy resin (hydroxyl equivalent 11
0, softening point 80 ° C.) 28 parts, (CH ₃ Si _3/2 ) _n organosilicone powder (average particle size 50 μ) 50
Parts, fusible silica powder 345 parts, silane coupling agent (Nippon Unicar Co., A-186) 2 parts, carbon black 2 parts, curing accelerator (2,4,6-trisdimethylaminomethylphenol) 0.45 Parts and 2.5 parts of the mold release agent carnauba wax are melt-kneaded with a hot roll at 80 to 100 ° C. for 3 minutes, cooled, and then pulverized into 10 mesh pass powder to obtain an epoxy resin composition for semiconductor element encapsulation. Obtained.

[0040]

Examples 2, 4, 6 The raw materials were used in the formulations shown in Table 1 below, and the types of silicone powder and silicone oil were changed. The target epoxy resin composition was obtained in the same manner as in Example 1 except for the above. The types of silicone powder used are shown in Table 2, and the types of silicone oil are shown in Table 3.

[0041]

Examples 3 and 5, Comparative Examples 1 to 3 Phenolic resins and silicone oils in the amounts shown in Table 1 were melt mixed in a separable flask equipped with a stirrer, and the curing accelerators in the amounts shown in Table 1 were added thereto. Add and stir mix at 170 ° C. for 4 hours. The total amount of the modified product obtained and the other raw materials shown in Table 1 were adjusted to 80 to 100.
The mixture was melted and kneaded for 3 minutes with a hot roll at 0 ° C., cooled, and then pulverized into 10 mesh pass powder to obtain an epoxy resin composition for encapsulating a semiconductor element. The types of silicone powder and silicone oil used are shown in Tables 2 and 3.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

Next, using the powdery epoxy resin compositions obtained in the above Examples and Comparative Examples, a 42-pin DI was used with a 48-cavity mold in order to investigate the filling property and the imprintability.
P was molded. The mold used was a low-pressure transfer molding method. That is, a tablet preheated to 90 ° C. using a high-frequency heating device was injected into a mold at 175 ° C. with a set injection time of 20 seconds and molding was performed for 2 minutes.

The surface of the 42-pin DIP molded product thus obtained was stamped with Bonmark C silver, post-cured at 175 ° C. for 5 hours, and then a cotton swab impregnated with trichlorethylene was applied to apply a load of 500 g, whereby the product disappeared completely. The number of round trips was calculated and evaluated.

In the thermal shock resistance test, 40 pieces were prepared by similarly molding the elements for thermal shock resistance test and then post-curing at 175 ° C. for 5 hours. This sample at 150 ° C
Alternately dipping in silicone oil at 80 ° C every 5 minutes for 500 cycles, then heat-dissolve and remove the package with fuming nitric acid, and remove the number of cracks in the silicon nitride film that is the protective film on the device surface. Seek and evaluate. The results are shown in Table 4 below.

[0048]

[Table 4]

From the results shown in Table 4, the products of the Examples have thermal shock resistance,
It can be seen that it is possible to realize a well-balanced and highly reliable semiconductor device, which is excellent in both filling properties and marking properties.

On the other hand, in the comparative examples, those without silicone powder have poor imprintability, those without silicone oil have poor filling properties, and those without both have poor thermal shock resistance.

Claims (1)

[Claims] 1. A semiconductor device obtained by encapsulating a semiconductor element with an epoxy resin composition containing the following components (A) to (D). (A) Epoxy resin. (B) Hardener. (C) A silicone powder represented by the following formula. Embedded image (RSiO _3/2 ) _n [wherein R is a monovalent organic group. (D) A silicone oil having at least one functional group selected from the group consisting of an epoxy group, an amino group, a hydroxyl group, a mercapto group and a carboxyl group.