JPS6345843A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the reliability and to gain low stress effect while securing the sealability and surface appearance by a method wherein a semiconductor element is sealed by epoxy resin compound containing specified kind of polysiloxane rubber. CONSTITUTION:Assuming alkyl group or alyl group as R, polysiloxane rubber is produced by making mixed-reaction of polysiloxane (silicon oil) A with functional group mainly comprising repeating unit represented by the formula I while added or added condense-reacted to each other as well as added or added condense-reacted to epoxy group with polysiloxane B mainly comprising the same unit reacted to each other as well as a hardener. A semiconductor element is sealed by means of epoxy resin compound mixed with the rubber, epoxy resin and the hardener. Through these procedures, the reliability can be improved by the low stress effect of rubber. Furthermore, the semiconductor element can be provided with excellent sealability and appearance during the formation process due to higher affinity between the rubber and the matrix resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having excellent characteristics such as moisture resistance and reliability.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are usually sealed with ceramic packages, plastic packages, or the like to form semiconductor devices. The above-mentioned ceramic package has heat resistance in the constituent material itself,
It also has excellent moisture resistance, so it is resistant to temperature and humidity.
Moreover, since it is a hollow package, it has high mechanical strength and can be sealed with high reliability. However, since the constituent materials are relatively expensive and the mass productivity is poor, resin sealing using the above-mentioned plastic package has recently become mainstream. Epoxy resin compositions have conventionally been used for this type of resin sealing, and have achieved good results.

The above-mentioned epoxy resin composition is particularly composed of an O-cresol novolac epoxy resin, a phenol novolac resin as a curing agent, a tertiary amine as a curing accelerator, fused silica as an inorganic filler, etc. These products have been praised for their excellent sealing workability (especially workability during transfer molding).

[Problem that the invention seeks to solve]

However, technological innovation in the semiconductor field is remarkable, and recently, along with improvements in the degree of integration, element sizes have become larger and
While interconnects are becoming finer, packages are becoming smaller and thinner, and along with this, encapsulation materials for semiconductor devices are also becoming more resistant to stress, heat, and moisture than ever before. Sexuality is now in demand. Conventional epoxy resin compositions for sealing have been sufficiently excellent as sealing materials for semiconductor elements such as ICs and LSIs, but for example, they are used for sealing large semiconductor devices with 8 or more pins, especially 16 pins or more. As for the material, shrinkage stress applied to the element becomes too large, which tends to cause a decrease in thermal shock resistance and an increase in residual stress.

These shortcomings are particularly noticeable when conducting thermal tests. That is, when a thermal test is performed on the above conventional large-sized semiconductor device, cracks, which serve as paths for moisture infiltration, occur in the sealing resin and the passivation film that is a protective film for the element. A device that cracks during a thermal test is likely to crack even under normal use, has poor moisture resistance and other characteristics, and lacks reliability as a semiconductor device.

In order to overcome these drawbacks, it has been proposed to add liquid rubber such as polybutadiene or silicone oil to the sealing resin to form domains of liquid rubber in the cured resin matrix to reduce stress. Silicone oil is often used from the viewpoint of moisture resistance. However, in general, when silicone oil is added, the imprintability of the resulting semiconductor device deteriorates, and mold stains increase during molding operations, resulting in poor appearance of the product.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device which has excellent characteristics such as moisture resistance and reliability, and which does not suffer from deterioration in stampability or deterioration in appearance.

[Means for solving problems]

In order to achieve the above object, the semiconductor device of the present invention includes:
The main components are epoxy resin and curing agent, and the following two types of polysiloxane (silicone) (A),
A configuration is adopted in which a semiconductor element is sealed using an epoxy resin composition containing polysiloxane rubber, which is a reaction product of (B).

(A) a polysiloxane containing one of two types of functional groups that undergo an addition or addition condensation reaction with each other and at least one of which reacts with an epoxy group and/or a curing agent, The following general formula (1
) A polysiloxane mainly composed of repeating units represented by

(B) A polysiloxane containing the other of the above two types of functional groups, which is mainly composed of repeating units represented by the above general formula CI).

That is, as a result of repeated research in order to eliminate the drawbacks caused by the use of silicone oil, the present inventor mixed two types of polysiloxanes having the above-mentioned specific functional groups, and by reaction with the two types of functional groups, When the resulting polysiloxane rubber is included in an epoxy resin composition, the low stress effect of the polysiloxane rubber improves reliability, and at the same time, the polysiloxane rubber reacts with the matrix resin component, The present invention was achieved by discovering that the affinity with the matrix resin is increased and the deterioration of marking properties and mold staining during molding work, which have been observed in the past, are no longer caused.

The epoxy resin composition used in this invention is obtained using polysiloxane rubber, which is a reaction product of the above two types of polysiloxanes (A) and (B), an epoxy resin, and a curing agent.

The above polysiloxane rubber may be synthesized in advance and mixed at the time of blending the epoxy resin composition, or the epoxy resin or curing agent as a matrix resin component is used as a reaction solvent, and the above two types of polysiloxane (A ), (B
) may be synthesized by reacting. The latter method is preferable because it improves the bonding property at the interface between the polysiloxane rubber and the matrix resin, and improves the thermal shock resistance of the resulting semiconductor device.

Of the above two types of polysiloxanes (A) and (B), (A) contains one of the two types of functional groups that undergo an addition or addition condensation reaction with each other. , is a polysiloxane mainly composed of repeating units represented by the above general formula (1,'). Here, "mainly" means that the polysiloxane is substantially composed of repeating units represented by the above general formula (1). Further, the polysiloxane (B) is a polysiloxane containing the other of the above two types of functional groups, and like the above polysiloxane (A), the polysiloxane (B) is a polysiloxane containing a repeating group represented by the above general formula (1). It is mainly based on units.

At least one of the above two types of functional groups is selected to be one that reacts with the matrix resin component, that is, the epoxy resin component or the curing agent component. As a result, the interface between the produced polysiloxane rubber and the matrix resin is well bonded, and the effects of improving low stress properties and thermal shock resistance are realized.

Two types of polysiloxanes (A) as described above.

(B) needs to be rubbery, and therefore has functional groups that can be made into rubber by mutual addition reaction or addition condensation reaction. Examples of the functional group include an epoxy group on one side and at least one type of functional group selected from an amino group, a carboxyl group, and a mercapto group on the other side. In this case, the above polysiloxane (A>, (B)
This effect can be achieved if n is 5 or more in the following repeating unit per functional group.

Further, the functional group may be present at the terminal end of the polysiloxane or as a side chain. The functional group and the silicone atom are usually bonded via an alkylene bond, but the bond is not limited to this.

The equivalent ratio of one functional group to the other functional group in the above two types of polysiloxanes (A) and (B) is 0.2 to 5.
．． 0 is preferable, and 0.5 to 2.0 is more preferable.

In the method of reacting the above polysiloxanes (A) and (B) to form polysiloxane rubber, the polysiloxanes are uniformly mixed together in advance, regardless of whether the polysiloxane rubber is synthesized in advance or in the matrix resin component. It is preferable to keep it. The temperature at which the polysiloxane is reacted to form a rubber is preferably set at a temperature of 100 to 250°C, more preferably 150 to 200°C.

The content of the polysiloxane rubber synthesized in this way in the epoxy resin composition is 5% by weight (hereinafter abbreviated as "%") of the total amount of the epoxy resin, curing agent, and polysiloxane rubber in the epoxy resin composition. ) or more and is preferably set to 25% or less. That is, if it is less than 5%, remarkable low stress properties cannot be obtained, whereas if it exceeds 25%, the package strength becomes weak and problems arise in handling. The above-mentioned polysiloxane rubber is dispersed and contained in the epoxy resin composition, and the smaller the particle size, the better the effect on thermal shock resistance and reduction of residual stress. In this case, the particle size is preferably set to 200 μm or less from the viewpoint of gate clogging when the epoxy resin composition is used in a transfer mold.

The epoxy resin which is the main component of the epoxy resin composition in which the above-mentioned polysiloxane rubber is dispersed contains 2 in 1 molecule.
There are no particular restrictions on the epoxy compound as long as it has at least two epoxy groups.

In other words, various epoxy resins such as novolac type epoxy resin, which has been conventionally used as a sealing resin for semiconductor devices, can be suitably used.In addition, diglycidyl ether of bisphenol A and Ebis type epoxy resin, which is a polymer thereof, can be suitably used. , bisphenol F type epoxy resin,
Resorcinol type epoxy resins, alicyclic epoxy resins, etc. can also be used as suitable epoxy resins.

The novolac type epoxy resin usually has an epoxy equivalent of 160 to 250. Those having a softening point of 50 to 130°C are used, and among these, Talesol novolac type epoxy resin has an epoxy equivalent of 180 to 210. Softening point 60-1
A temperature of 10°C is generally used. In addition, as a phenol novolak type epoxy resin, the epoxy equivalent is 160
~200°C and a softening point of 60~110°C are generally used.

Suitable examples of the curing agent used with the above epoxy resin include novolac type phenolic resin, acid anhydride, and amine, and these can be used alone or in combination.

Examples of the novolac type phenolic resin include phenol novolac resins and talesol novolac resins obtained by condensing phenols such as phenol, cresol, and bisphenol A with aldehydes such as formaldehyde under an acidic catalyst.

Examples include bisphenol A novolak resin, and those having a softening point of 50 to 130°C are particularly preferred.

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

In addition, as the amine, m-phenylenediamine, p-
Phenylene diamine, 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-〇-aminophenyl)benzene, 1,3-diamino-
4-isopropylbenzene, m-xylylenediamine,
p-xylylene diamine, 2,4-diaminotoluene,
2.6-diaminotoluene, bis(4-aminocyclohexyl)methane, 3-methylhebutamethylenediamine,
4.4-dimethylhbutamethylenediamine, octamethylenediamine, 2.5-dimethylhexamethylenediamine, 2.5-methylhexamethylenediamine, 3-methylhbutamethylenediamine, 1,4-cyclohexanediamine, etc. I can give it to you.

Moreover, in this invention, other raw materials such as a curing accelerator, a filler, a mold release agent, etc. can be used as necessary in addition to the above-mentioned raw materials. As the curing accelerator, any substance that acts as a catalyst for the curing reaction of the epoxy resin can be used, for example,
Examples include 2,4.6-)li(dimethylaminomethyl)phenol, 2-methylimidazole, and triphenylphosphine. As the filler, quartz glass powder, silica sand powder, talc, etc. can be used. As the mold 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.

The epoxy resin composition used in the present invention can be produced as follows, for example, when a novolac type phenol resin or an acid anhydride is used as a curing agent. That is, first, at least one of the epoxy resin and the curing agent is heated and melted, and a premixed mixture of two or more polysiloxanes (silicone oils) having mutually reactive functional groups, such as epoxy group The dimethylpolysiloxane containing dimethylpolysiloxane and the polydimethylsiloxane containing amino groups are heated and stirred while being dropped, and after the reaction is completed, the epoxy resin or curing agent containing polysiloxane rubber (silicone rubber) is obtained. It can be produced by mixing the other of the resin and the curing agent with other raw materials such as a curing accelerator, a mold release agent, and a filler as needed, and kneading the mixture at 80 to 120°C for several minutes. When using a curing accelerator, the amount added is usually adjusted so that the gelation time at 150° C. of the resulting epoxy resin composition is 30 to 90 seconds. When an amine curing agent is used as the agent, it is preferable to synthesize the silicone rubber in the epoxy resin or the curing agent in advance, pulverize it, and then triblend all the components.

In this invention, the content of the curing agent is a sufficient amount to solidify the epoxy resin, that is, 0.4 to 2.0 per 1 epoxy equivalent of the epoxy resin.
It is preferred to use equivalents, preferably 0.6 to 1.5 equivalents. More specifically, when a novolac type phenol resin is used as a curing agent for 1 epoxy equivalent of the epoxy resin, 0.5 to 2.0 equivalent, preferably 0.
．． 8 to 1.5 equivalents, or 0.4 to 1.2 equivalents when an acid anhydride is used as a curing agent, preferably 0.6 to 1
．． When an amine is used as a curing agent, it is preferably 0.5 to 2.0 equivalents, preferably 0.8 to 1.5 equivalents.

Sealing of a semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a conventional method, for example, a known molding method such as transfer molding.

The semiconductor device thus obtained has extremely low stress properties and excellent marking properties and surface appearance.

〔Effect of the invention〕

As described above, the semiconductor device of the present invention is encapsulated using a special epoxy resin composition containing a three-dimensionally crosslinked polysiloxane rubber that has bonding properties at the interface with a matrix resin, and the encapsulating plastic Since the package is different from conventional epoxy resin compositions, it is possible to reduce stress while maintaining sealability and surface appearance during continuous production. In particular, sealing with the special epoxy resin composition mentioned above can be used to seal very large scale integrated circuits, etc., and even in large semiconductor devices with an element size of 16 m" or more, it is possible to improve the sealability during continuous production as described above. High reliability can be achieved without compromising surface appearance.
This is its biggest feature.

Next, examples will be described together with comparative examples.

[Example 1] 0-talesol novolac epoxy resin (epoxy equivalent weight 220, softening point 80) in a separable flask with a stirrer
°C) 56 parts by weight (hereinafter abbreviated as "parts") are heated and melted, and into this are added 5 parts of both-terminated aminopropyl polydimethylsiloxane (amine equivalent: 10,000) and both-terminated glycidylpropyl polydimethylsiloxane, which have been uniformly mixed at room temperature in advance. (
A mixture of 10 parts of epoxy equivalent (10,000) was added dropwise with stirring, and after the dropwise addition, the mixture was stirred at 200°C for 10 hours. A panoramic view of the obtained contents and 28 parts of phenol novolac resin (hydroxyl equivalent: 110, softening point: 80°C), 257 parts of fusible silica powder, 2 parts of silane coupling agent (A-186, manufactured by Nippon Unicar Co., Ltd.), hardening accelerator 0.45 parts of agent (2,4,6-)lisdimethylaminomethylphenol) and 2.5 parts of mold release agent (carnauba wax) were heated at 80 to 100°C.
Melt and knead for 3 minutes in a hot mill, cool, and then crush.
10 mesh pass powder was used to obtain an epoxy resin composition for semiconductor encapsulation. Then, using this, a semiconductor device was manufactured in the following manner.

[Example 2] Side chain aminopropyl polydimethylsiloxane (amine 3
12009 molecular weight 3000) 12 parts and terminal glycidylpropyl polydimethylsiloxane (1500 per epoxy)
12 parts were uniformly premixed. 0-Taresol novolac epoxy resin (epoxy ff1230. Softening point 7
5° C.) was heated and melted in a flask, and the light premix was added dropwise while stirring and mixing with a disper. After the dropwise addition, the mixture was stirred at 180° C. for 10 hours. An epoxy resin composition was obtained in the same manner as in Example 1, except that the entire content obtained and 25 parts of a phenol novolac resin (itl 10° per hydroxyl group, softening point 80°C) were used.

[Example 3] Polydimethylsiloxane having glycidylpropyl and polypropylene glycol in the side chain (epoxy
I 000. Glycol content 50%) 2.5 parts and terminal mercaptopropyl polydimethylphenylsiloxane (methyl/phenyl ratio = 20/1. mercapto ff
15,000) were uniformly premixed. Phenol novolac resin (hydroxyl equivalent: 110. Softening point: 80t)
34 parts were heated and melted in a flask, and while stirring and mixing with a disper, the previous premix was added dropwise, and after dropping, 17 parts
The mixture was stirred at 0°C for 12 hours. The total amount of the obtained contents and O-talesol novolac epoxy resin (epoxy equivalent: 220
．． An epoxy resin composition was obtained in the same manner as in Example 1 except that 68 parts (softening point: 80°C) were used.

[Example 4] 5 parts of side-chain glycidylpropyl polydimethylsiloxane (1200 per epoxy, molecular weight 3000) and 1 part of terminal carboxypropyl polymethylphenylsiloxane (methyl/phenyl ratio = 10/1. 1600 per carboxyl)
0 parts were uniformly premixed. The subsequent steps are Example 1
An epoxy resin composition was obtained in the same manner as above.

[Example 5] 10 parts of terminal aminopropyl polydimethylsiloxane (15,000 amine equivalent) and 2 parts of terminal glycidylpropyl polydimethylsiloxane (epoxy equivalent 500) were uniformly mixed and heated at 260°C for 20 hours under a nitrogen stream. A gummy substance was obtained. The total amount of the obtained rubbery substance, 60 parts of 0-talesol novolac epoxy resin (epoxy equivalent fi 220, softening point 80°C), 30 parts of phenol novolac resin (hydroxyl equivalent 110, softening point 80°C), 260 parts of fusible silica powder 1 part, 2 parts of silane coupling agent (A-186, Nippon Unicar Co., Ltd. vg), 2 parts of carbon black, 0.45 part of curing accelerator (2,4,6-)lith dimethylaminomethylphenol), and mold release agent ( carnauba wax) 2
．． 5 parts were kneaded for 3 minutes using a hot roll of 80-100 t'. Next, this was cooled and pulverized to obtain a 10 mesh pass powder to obtain an epoxy resin composition for semiconductor encapsulation.

[Comparative Example 1] The same procedure as in Example 1 was carried out except that 15 parts of aminopropylpolydimethylsiloxane were used, glycidylpropylpolydimethylsiloxane was not used, and the reaction temperature was 170°C.

[Comparative Example 2] The same procedure as Example 1 was carried out except that polydimethylsiloxane was not used and the preliminary reaction with the epoxy resin was not performed.

<Manufacture of semiconductor devices> Using the above powdered epoxy resin composition, 42-pin DIP was performed in a 48-cavity mold to examine the surface appearance and marking properties.
300 shots were continuously molded. The mold used 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. for an injection time of 20 seconds, and molded for a molding time of 2 minutes.

The thus obtained 42-pin DIP molded product was subjected to the following tests (surface appearance, imprintability, thermal shock resistance). That is, the surface appearance quality was determined by visual inspection of the molded product, and the marking property was determined by stamping Bonmark C silver on the surface of the molded product, post-curing it at 175°C for 5 hours, and then applying a load of 500 g with a cotton swab soaked in trichlorethylene. ,
Evaluation was performed by calculating the number of round trips until it completely disappeared.

In addition, for the thermal shock test, 40 elements for the thermal shock test were molded in the same manner and post-cured at 175° C. for 5 hours. This sample was heated to 150°C and -80°C.
The package was immersed in silicone oil for 5 minutes alternately for 500 cycles, and then the package was heated and dissolved with fuming nitric acid to remove it, and the number of cracks found in the silicon nitride film, which is the protective film on the element surface, was determined. evaluated.

The results of the above tests are summarized in Table 1 below.

(Left below) 11'' - 11 As mentioned above, the implemented product is excellent in thermal shock resistance, surface appearance, and stamping properties, making it a well-balanced and highly reliable semiconductor device. I understand that there is something.

Procedural amendment issued October 3, 1985 1.11 Cow's 1989 Printed by the old man sacrificial seaweed No. 189406 2, Name of the invention Semiconductor device 3, Person making the amendment Relationship to the case Patent applicant's address Formerly No. 1, 1-1-2 Name (396) Nitto Electric Industry Co., Ltd. No. 7, Contents of amendment (1) Page 7, line 9 of the specification, ``Increased affinity ``As before,'' was replaced with ``Increased affinity.''
Since the above-mentioned siloxane rubber is in solid form, it has been corrected as before.

(2) On page 19, line 13 of the specification, the phrase ``while combining the light premix'' is corrected to ``while combining the previous premix.''

8. List of attached documents

Claims (2)

[Claims] (1) Semiconductor elements can be fabricated using an epoxy resin composition containing an epoxy resin and a curing agent as main components and polysiloxane rubber which is a reaction product of the following two types of polysiloxanes (A) and (B). A semiconductor device that is sealed. (A) a polysiloxane containing one of two functional groups that react with each other and at least one of which reacts with an epoxy resin and/or a curing agent; A polysiloxane whose main component is a repeating unit represented by the general formula (I) below. ▲There are mathematical formulas, chemical formulas, tables, etc.▼... (I) R is an alkyl group or an aryl group, and they may be the same or different. (B) A polysiloxane containing the other of the above two types of functional groups, which is mainly composed of repeating units represented by the above general formula (I). (2) The semiconductor device according to claim 1, wherein one functional group is an epoxy group and the other functional group is at least one functional group selected from an amino group, a carboxyl group, and a mercapto group.