JPH0682764B2 - Semiconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a semiconductor device having excellent reliability.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are usually sealed by a ceramic package or a plastic package to form a semiconductor device. The above-mentioned ceramic package is resistant to temperature and humidity because the constituent material itself has heat resistance and excellent moisture resistance, and since it is a hollow package, mechanical strength is high and highly reliable sealing is possible. Is. However, since the constituent materials are relatively expensive and the mass productivity is inferior, the resin sealing using the plastic package has recently become the mainstream. An epoxy resin composition has been conventionally used for this type of resin encapsulation, and has achieved good results.

Examples of the epoxy resin composition include an o-cresol novolak epoxy resin, a phenol novolak resin as a curing agent, a tertiary amine compound as a curing accelerator, and fused silica as an inorganic filler. The structured materials are prized for their excellent sealing workability (especially workability during transfer molding).

[Problems to be solved by the invention]

However, technological innovation in the semiconductor field has been remarkable, and recently, with the increase in integration degree, the device size has become larger,
On the other hand, the miniaturization of wiring is advancing, but the miniaturization and thinning of the package shape are also advancing. As a result, even in the encapsulating material of semiconductor elements, the stress, heat resistance, and moisture resistance are higher than ever before. Sex is becoming required. The conventional epoxy resin compositions for encapsulation are sufficiently excellent as encapsulating materials for semiconductor elements such as ICs and LSIs. However, for example, encapsulating materials for large semiconductor devices with 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 thermal test is conducted. That is, when the conventional large-sized semiconductor device is subjected to a cooling / heating test, a crack which becomes a moisture intrusion path is generated in the passivation film which is a protective film for the sealing resin and the element. As described above, an apparatus that causes cracks in the cooling / heating 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. However, when silicone oil is added, marking is performed when a mark is displayed on the encapsulating resin part of the obtained semiconductor device. There is a problem such as poor performance.

The present invention has been made in view of such circumstances, and by using a special component composition as an epoxy resin composition used for resin encapsulation, it is possible to sufficiently cope with encapsulation of large semiconductor devices, etc. It is an object of the present invention to provide a semiconductor device that is remarkably excellent in characteristics such as stress resistance, imprintability, and moisture resistance.

[Means for solving problems]

In order to achieve the above object, the semiconductor device of the present invention,
A semiconductor element is sealed 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.

(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.

That is, the present inventors have conducted a series of researches centering on the silicone-based material used in the epoxy resin composition in order to improve the low stress property without impairing the imprintability of the semiconductor device. The inventors have found that the intended purpose can be achieved by using a specific silicone oil in combination with a silicone powder represented by the general formula (RSiO _3/2 ) _n , and have reached the present invention.

The epoxy resin composition used in the present invention comprises an epoxy resin (A component), a curing agent (B component), a silicone powder (C component) represented by the above general formula, and a specific silicone oil (D component). Which can be obtained by using
Usually, it is in the form of powder or a tablet formed by compressing it.

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

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 kinds of epoxy resins conventionally used as sealing resins for semiconductor devices are suitable, and in addition, diglycidyl ether of bisphenol A and its multimers, epibis type epoxy resin, bisphenol F type epoxy resin,
Resorcin type epoxy resin, alicyclic epoxy resin and the like can also be used as suitable epoxy resins.

As a novolak type epoxy resin, usually epoxy equivalent
A cresol novolak type epoxy resin having an epoxy equivalent of 180 to 210 and a softening point of 60 to 110 ° C is generally used as the cresol novolak type epoxy resin. The phenol novolac type epoxy resin has an epoxy equivalent of 160 to 200 ° C and a softening point of 60 to 110 ° C.
Those generally used.

Suitable examples of the B component curing agent used together with the above epoxy resin include novolak type phenol resins, acid anhydrides and amines, and these can be used alone or in combination.

Examples of the novolak type phenol resin include phenol novolak resin, cresol novolak resin, and bisphenol A obtained by condensing phenols such as phenol, cresol, and bisphenol A and aldehydes such as formaldehyde under acidic catalyst. Examples thereof include novolak resins, and those having a softening point of 50 to 130 ° C. are particularly preferable.

As the acid anhydride, phthalic anhydride, maleic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, methylendomethylenetetrahydrophthalic anhydride, cyclohexane-1,2-
Examples thereof include dicarboxylic acid anhydride, cyclohexane-3,4-dicarboxylic acid anhydride, and ethylene glycol ester of 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-isobropyr Benzene, m-xylylenediamine, p-xylylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, bis (4-aminocyclohexyl) methane, 3-methylheptamethylenediamine, 4,4-dimethylhepta Methylenediamine, octamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethyle Diamine,
1,4-cyclohexanediamine and the like can be mentioned.

The component C silicone powder used in the present invention is different from the conventionally known linear polymers or rubber-like silicone rubbers, and further, silicone compounds such as silicone oil, are represented by the general formula (RSiO _3/2 ) _n Is a powder of organopolysiloxane having a dense three-dimensional network structure. That is, this silicone powder has the following structure, for example: And a portion surrounded by a dotted line is a repeating unit.

Since the smaller the particle size of the silicone powder, the more preferable effect on the thermal shock resistance and the reduction of 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.

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

Incidentally, in the above formula of silicone powder, R is a monovalent organic group as described above, but specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a cycloalkyl group and the like. Alkyl groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and xylyl groups, aralkyl groups such as phenylethyl groups, or epoxy groups, amino groups, hydroxyl groups, carboxyl groups,
A monovalent organic substituent having a carboxylic acid ester group or a mercapto group can be used.

The silicone powder used in the present invention may be either 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. Good.

Further, the component D silicone oil used in the present invention is
Silicone having a function as a resin type modifier such as an epoxy resin and a curing agent and 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. Composed of oil. This oil may be used alone,
You may use several types together. 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 functional group, even if bonded to the silicone molecule terminal,
It may be bonded as a side chain.

The molecular weight of such silicone oil is 100 or more and 10,000 or more.
It is preferably 0 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 reduce the reliability of the semiconductor device, and conversely, the molecular weight is 100000.
When it exceeds, the silicone molecule does not show an affinity for the resin system, and it becomes substantially difficult to chemically react with the resin system, that is, to modify, and the effect of the present invention becomes small.

The equivalent weight per functional group is preferably 100 or more and 100000 or less. This is for the same reason as above.

It is preferable that the silicone oil of the present invention is previously 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, the above-mentioned A component, B component, C component and D
In addition to the components, other raw materials such as a curing accelerator, a filler and a release agent can be used if necessary. As the curing accelerator, any one that serves as a catalyst for the curing reaction of a phenol-cured epoxy resin can be used, and examples thereof include 2,4,6-tri (dimethylaminomethyl) phenol, 2-methylimidazole and triphenylphosphine. Etc. can be given. 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, ester waxes and the like can be used. it can.

The epoxy resin composition used in the present invention can be produced as follows when a novolac type phenol resin or an acid anhydride is used as the curing accelerator which is the component B, for example. That is, first, the epoxy resin (A
Component) and / or curing agent (B component) is modified with silicone oil (D component), and the modified product and silicone powder (C component) and, if necessary, a curing accelerator, release agent, filler, etc. It can be produced by mixing other raw materials and kneading at 80 to 120 ° C for several minutes. When a curing accelerator is used, it is usually used by adjusting the addition amount so that the gelling time of the resulting 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 previously melt-kneaded with the epoxy resin or the curing agent and finely pulverized, and all the components are dry-blended.

In this invention, the content of the curing agent (component B) is
It is preferable to use an amount sufficient to cure the epoxy resin (component A), that is, 0.4 to 2.0 equivalents, preferably 0.6 to 1.5 equivalents, per 1 epoxy equivalent of the epoxy resin.

More specifically, when a novolak 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,
When an acid anhydride is used as the curing agent, 0.4 to 1.2
Equivalent, preferably 0.6 to 1.0 equivalent, further 0.5 to 2.0 equivalent when amine is used as a curing agent, preferably 0.8 to
It is desirable to use 1.5 equivalents.

Further, the content of the silicone powder (C component) is 2% by weight (hereinafter abbreviated as "%") or more based on the entire epoxy resin composition, and the addition amount including the inorganic component is 80% or less. Is preferred. That is, if it is less than 2%, 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. Further, if the total amount of the silicone powder and the inorganic component added exceeds 80%, the dispersibility and fluidity of the encapsulating resin composition will be problematic, and the resulting semiconductor device will be defective because the encapsulating resin is not filled. Is.

Further, the content of the silicone oil (D component) should be 15% or less with respect to the epoxy resin composition (A component + B component + C component + D component) excluding additional components such as a curing accelerator and a filler. preferable. This is because if it exceeds 15%, a problem is likely 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 performed by an ordinary method, for example, a known molding method such as transfer molding.

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

[Effects of the Invention] As described above, the semiconductor device of the present invention is sealed using 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 imprintability 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 in a large-sized semiconductor device with an element size of 16 mm ² or more, to obtain the above high reliability. This is the greatest feature.

Next, examples will be described together with comparative examples.

First, an epoxy resin composition was prepared as follows.

[Example 1] In a separable flask equipped with a stirrer, 56 parts by weight of o-cresol novolac epoxy resin (epoxy equivalent: 220, softening point: 80 ° C) (hereinafter abbreviated as "part") was heated and melted. Propyl polydimethyl siloxane (amine equivalent 10
000) 15 parts were added, and the mixture was stirred and mixed at 170 ° C. for 4 hours. The total amount of the obtained modified product and 28 parts of phenol novolac epoxy resin (hydroxyl equivalent 110, softening point 80 ° C), (CH ₃ RSiO _3/2 ) _n
Organosilicone powder represented by (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 release agent Karnawawax are melt-kneaded with a hot roll at 80 to 100 ° C. for 3 minutes, cooled, and then crushed to obtain 10 mesh pass powder to obtain an epoxy resin composition for encapsulating a semiconductor device. It was

[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.

[Examples 3, 5 and Comparative Examples 1 to 3] The amounts of the phenol resin and silicone oil shown in Table 1 were melt-mixed in a separable flask equipped with a stirrer, and the amount of the curing accelerator shown in Table 1 was added thereto. And add at 170 ° C for 4
Stir and mix for hours. The whole amount of the modified product obtained and the other raw materials shown in Table 1 were melt-kneaded with a hot roll at 80 to 100 ° C. for 3 minutes, cooled, and then pulverized to obtain 10 mesh pass powder, which was used as an epoxy for semiconductor element encapsulation. A resin composition was obtained. The types of silicone powder and silicone oil used are shown in Tables 2 and 3.

Next, using the powdery epoxy resin compositions obtained in the above Examples and Comparative Examples, a 42-pin DIP was molded with a 48-cavity mold in order to investigate the filling property and the imprintability. As the mold, a low pressure transfer molding method was used. That is, a tablet preheated to 90 ° C. was injected into a mold at 175 ° C. with a set injection time of 20 seconds using a high frequency heating device, 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 loaded with a cotton swab soaked with trichlorethylene to a load of 50.
It was evaluated by multiplying by 0 g and determining the number of round trips until it completely disappeared.

The thermal shock resistance test was performed by molding a thermal shock resistance test element in the same manner and then post-curing at 175 ° C for 5 hours.
I prepared one. This sample was alternately immersed in silicone oil at 150 ° C and -80 ° C every 5 minutes for 500 cycles, and then the package was dissolved by heating with fuming nitric acid to remove it, and silicon nitride as a protective film on the element surface was removed. The number of cracked films was found and evaluated. The results are shown in Table 4 below.

From the results shown in Table 4, it is understood that the example products are excellent in all of thermal shock resistance, filling property and sealability, and can realize a balanced and highly reliable semiconductor device.

On the other hand, in the comparative example products, the one without silicone powder has a poor stamping property, the one without silicone oil has a poor filling property, and the one without both has 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. (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.