JP2000068418A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve solder heat resistance, heat shock resistance, moisture resistance reliability, etc., by covering a semiconductor element with an epoxy resin compsn., contg. a compd. shown by a specified formula, a part of or the entire top face of the element having been covered with a polyimide obtd. by dehydrating a polyimide precursor having structural units represented by a specified formula. SOLUTION: A part of or the entire top face of a semiconductor element is covered with a polyimide obtd. by dehydrating a polyimide precursor having structural units as a main component, represented by Formula I (R1 is a trivalent or tetravalent org. group having two C atoms, R2 is a bivalent org. group having two C atoms, K is ammonium ion having an org. group contg. a double bond and n is 1 or 2). The semiconductor element is further covered with an epoxy resin compsn. contg. an epoxy resin which contain a compd. shown by Formula II (R3-R10 are H atoms, monovalent org. group or halogen atoms), phenol-based hardening agent, hardening accelerator, inorg. filler, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a semiconductor element whose upper surface is partially or wholly coated with polyimide is coated with an epoxy resin composition. The present invention relates to a semiconductor device having excellent reliability such as impact resistance and humidity resistance.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc. and can be imparted with various properties by blending and prescription. Have been.

For example, as a method for sealing electronic circuit components such as semiconductor devices, a hermetic seal made of metal or ceramic and a phenol resin, silicone resin,
Resin sealing using an epoxy resin or the like has been proposed, and a resin used for such sealing is generally called resin sealing. Among them, resin sealing with an epoxy resin is most actively performed in terms of balance between economy, productivity and physical properties.

Recently, the density and automation of mounting a semiconductor device package on a printed circuit board have been increased, and instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the board, the package is soldered to the surface of the board. “Surface mounting method” has become popular. Along with this, the package has changed from the conventional DIP (dual in-line package) to a thin F package suitable for high-density mounting and surface mounting.
Moving to PP (flat plastic package). Among them, TSOP, TQFP, and LQFP having a thickness of 2 mm or less have recently become mainstream due to advances in fine processing technology.

[0005] Therefore, it is more susceptible to external influences such as humidity and temperature, and reliability such as solder heat resistance, high temperature reliability, thermal shock resistance, and humidity resistance will become increasingly important in the future.

As a device for improving the reliability, more studies have been made than before. For example, JP-A-1-73
Japanese Patent No. 749 proposes a reduction of ionic impurities in the raw materials constituting the epoxy resin composition, and Japanese Patent Application Laid-Open No. 1-84739 discloses that a specific area of the rubber-like silicone is specified in the epoxy resin composition. It is proposed to include more than the amount of fusible silica. In addition, Japanese Patent Laid-Open No. 4-1
No. 88856 proposes to use a mixture of surface irregular silica having a large average particle size and ordinary silica having a small average particle size, and JP-A-4-153213 discloses that a specific epoxy resin, Has been proposed to contain a phenol novolak curing agent, a curing accelerator, and an inorganic filler. JP-A-6-239975 discloses that a cured product of a low-stress epoxy resin composition is contained. Has been proposed.

However, even if these techniques are used, the reliability such as solder heat resistance, high-temperature reliability, thermal shock resistance and moisture resistance cannot be sufficiently satisfied, and the reliability is insufficient. there were.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having high reliability, which is excellent in all items of solder heat resistance, high temperature reliability, thermal shock resistance, and moisture resistance.

[0009]

SUMMARY OF THE INVENTION Frequently, semiconductor devices include
Polyimide is formed on the surface of the semiconductor element for the purpose of relaxing stress between the sealing resin and the element and shielding α rays from the sealing resin.

The present inventors have developed a semiconductor device coated with a polyimide obtained by dehydrating a polyimide precursor having a specific structure, and an epoxy resin containing an epoxy resin having a specific structure. The inventors have found that the above object has been achieved by a semiconductor device constituted by a combination with a resin composition, and a semiconductor device meeting the purpose can be obtained.

That is, the present invention has the following configuration.

A semiconductor element partially or wholly coated with polyimide is sealed with an epoxy resin containing an epoxy resin (A), a phenolic curing agent (B), a curing accelerator (C), and an inorganic filler (D). In a semiconductor device coated with a resin stopper composition, the polyimide is a polyimide obtained by dehydrating a polyimide precursor having a structural unit represented by the general formula (I) as a main component, and the epoxy resin (A ) Is an epoxy resin composition containing a compound represented by the general formula (II).

[0013]

Embedded image (R ₁ represents a trivalent or tetravalent organic group having at least 2 carbon atoms, R ₂ represents a divalent organic group having at least 2 carbon atoms, and n is 1 or 2.)

Embedded image (However, R _{3 to} R ₁₀ in the formula represent a hydrogen atom, a monovalent organic group or a halogen atom.)

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

First, the epoxy resin composition which is one of the constituent elements of the semiconductor device of the present invention will be described in detail.

The epoxy resin composition according to the present invention comprises:
It contains an epoxy resin (A), a phenolic curing agent (B), a curing accelerator (C), and an inorganic filler (D), and the epoxy resin (A) contains a compound represented by the general formula (II). It is a resin composition.

[0017]

Embedded image (However, R _{3 to} R ₁₀ in the formula represent a hydrogen atom, a monovalent organic group or a halogen atom.) In the present invention, the epoxy resin (A) uses a compound represented by the general formula (II) alone. Alternatively, an epoxy resin having another structure may be used in combination. In that case, the compounding ratio of the compound represented by the general formula (II) is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, further preferably 90 to 100% by weight of the whole epoxy resin.
% By weight.

Specific examples of the epoxy resin skeleton represented by the general formula (II) include 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy). ) -3,3 ′, 5,5′-tetramethylbiphenyl, 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethyl-2-chlorobiphenyl, , 4'-Bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2-
Bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3' , 5,5'-tetrabutylbiphenyl,
4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl and the like. Preferably, 4,4'-bis (2,3
-Epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl and 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetraethylbiphenyl. More preferably, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'
-Tetramethylbiphenyl.

Each of the above epoxy resins may be used alone,
Alternatively, even when used in a mixed system, the effect is sufficiently exhibited.
Further, a compound in which the epoxy resin is partially added by a reaction of an epoxy group can also be used.

In the present invention, the viscosity of the epoxy resin (A) is not particularly limited, but the ICI melt viscosity at 150 ° C. is 3 p.p.
Epoxy resins of s or less are preferred.

In the present invention, the epoxy resin (A)
Is usually 1 to 1 in the epoxy resin composition.
It is 12% by weight, preferably 3 to 10% by weight, more preferably 3 to 8% by weight. If the amount of the epoxy resin (A) is small, the moldability and adhesiveness become insufficient. If the amount is too large, the coefficient of linear expansion increases, the stress tends to be reduced, and the reliability tends to decrease.

The phenolic curing agent (B) in the present invention
Is not particularly limited as long as it is a phenolic compound which is cured by reacting with the epoxy resin (A). Specific examples thereof include various phenolic novolak resins, cresol novolak resins, various novolaks synthesized from bisphenol A, resorcinol, and the like. Resins and various polyhydric phenol compounds can be exemplified. From the viewpoint of reliability, a compound represented by the general formula (III) can be preferably mentioned. Two or more phenolic curing agents may be used in combination.

In the general formula (III), R ¹ is a divalent aromatic group having no hydroxyl group, R ² is a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, R ^{1 to} R ³ may be the same or different, and n is 0 or 1
Is an integer greater than or equal to.

[0024]

Embedded image (Where R ¹ in the formula (III) is a divalent aromatic group, R ² is a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, R ^{1 to} R ³ May be the same or different, and n represents 0 or an integer of 1 or more.) Of the compounds represented by the general formula (III), preferred examples are those in which R ¹ is a divalent phenyl group, R ² Is a divalent phenyl group having a hydroxyl group, a phenolic curing agent wherein R ³ is a monovalent phenyl group having a hydroxyl group, and R ¹ is a divalent biphenyl group, and R ² is a divalent phenyl group having a hydroxyl group; R ³ is a phenolic curing agent having a hydroxyl group-containing monovalent phenyl group, or R ¹ is a divalent biphenyl group, R ²
And a phenolic curing agent in which R ³ is a divalent phenyl group having a hydroxyl group and R ³ is a monovalent phenyl group having a hydroxyl group.

When a phenolic curing agent represented by the general formula (III) and another phenolic curing agent are used in combination, the mixing ratio of the phenolic curing agent represented by the general formula (III) is considered from the viewpoint of moisture resistance reliability. Content of the system-based curing agent is 20 to 100% by weight, 50 to 100% by weight, 70
To 100% by weight, and preferably 80 to 100% by weight.
In the present invention, the blending amount of the phenolic curing agent (B) is usually 0.1 to 10% by weight, preferably 0.5 to 7% by weight, more preferably 1 to 10% by weight of the whole epoxy resin composition.
6% by weight. Furthermore, the mixing ratio of the epoxy resin (A) and the phenolic curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.5 to 1.5 in view of mechanical properties and moisture resistance reliability. In particular, it is preferably in the range of 0.8 to 1.2.

In the present invention, the curing accelerator (C) is not particularly limited as long as it promotes the curing reaction between the epoxy resin (A) and the phenolic curing agent (B). For example, imidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, 1
-Methylimidazole, 1,2-dimethylimidazole, 1-vinylimidazole, 2-methyl-1-vinylimidazole, 2-methyl-1-vinylimidazole,
1-allylimidazole, 1- (2-hydroxyethyl) imidazole, 1- (2-hydroxyethyl) -2
-Methylimidazole, 1-phenylimidazole, 1
-Benzylimidazole, 1-benzyl-2-methylimidazole, 2-aminoimidazole, 2-nitroimidazole, tetrabutylphosphonium / tetraphenylborate, n-butyltriphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / tetraphenylborate, Trimethylphenylphosphonium / tetraphenylborate, diethylmethylphenylphosphonium / tetraphenylborate, diallylmethylphenylphosphonium / tetraphenylborate,
(2-hydroxyethyl) triphenylphosphonium / tetraphenylborate, ethyltriphosphonium /
Tetraphenylborate, p-xylenebis (triphenylphosphonium / tetraphenylborate), tetraphenylphosphonium / tetraethylborate, tetraphenylphosphonium / triethylphenylborate,
Tetraphenylphosphonium / tetrabutyl borate,
Examples include triphenylphosphine and 1,8-diazabicyclo (5,4,0) undecene-7. More preferred examples include tetraphenylphosphonium tetraphenylborate, triphenylphosphine, 1,8-diazabicyclo (5,4,0) undecene-7, 2-methylimidazole, and the like. Two or more curing accelerators may be used in combination.

The addition amount of the curing accelerator (C) in the present invention is not particularly limited, but preferably the total weight of the curing accelerator is 0.05 to 1.5 parts by weight of the epoxy resin composition.
% Is preferred. It is more preferably 0.08 to 1.0%, and still more preferably 0.1 to 0.5%.

In the present invention, the inorganic filler (D) includes silica, calcium carbonate, magnesium carbonate, alumina, magnesia, magnesium aluminum oxide, zirconia, zircon, clay, talc, calcium silicate, titanium oxide, antimony oxide, Asbestos, glass fibers, and the like. Preferably silica, alumina,
Zirconia, and more preferably silica. The inorganic filler may be used alone or in combination of two or more. When silica is contained as an inorganic filler, the shape of the silica is not particularly limited, and may be spherical, crushed, fibrous, and the like, preferably spherical, crushed, and more preferably fluid. It is spherical from the point of sex. A combination of inorganic fillers having different shapes, for example, a combination of crushing and spherical shape may be used. Although there is no particular limitation on the spherical silica, spherical fused silica, spherical synthetic silica, spherical processed products of natural silica and the like can be mentioned, and spherical fused silica and spherical synthetic silica are preferred.

When silica is contained in the inorganic filler (D) in the present invention, the mixing ratio of silica in the inorganic filler is preferably from 90 to 100%, more preferably from 95 to 100%, from the viewpoint of reducing stress. And more preferably 98 to
100%.

The average particle diameter of the inorganic filler (D) in the present invention is preferably 5 from the viewpoint of fluidity and stress dispersion.
２５25 μm, more preferably 5-20 μm, and even more preferably 6-15 μm.

The maximum particle size of the inorganic filler (D) in the present invention is preferably not more than 95 μm, more preferably not more than 70 μm. The reasons for this are the prevention of package unfilling and wire flow during molding,
And wire disconnection prevention.

In the present invention, the ratio of the inorganic filler (D) to the entire epoxy resin composition is not particularly limited, but it is difficult for mold contamination to occur, the water absorption of the resin composition is reduced, and the reliability is improved. From the viewpoint that the coefficient of thermal expansion is made closer to that of a semiconductor element or a lead frame and the reliability is improved, it is preferably 70 to 96% by weight, more preferably 80 to 95% by weight, and still more preferably 8 to 95% by weight.
6-92%.

The following substances can also be added to the epoxy resin composition of the present invention.

In the epoxy resin composition of the present invention, it is preferable to mix a silane coupling agent, a titanate coupling agent and the like from the viewpoint of improving reliability. Further, it is also effective to previously treat the surface of the inorganic filler (D) with a coupling agent such as a silane coupling agent or a titanate coupling agent.

As the coupling agent, a silane coupling agent in which an organic group having such a functional group and a hydrolyzable group such as an alkoxy group are directly bonded to a silicon atom, such as epoxysilane, aminosilane, and mercaptosilane, is preferably used. Preferred are epoxysilane and aminosilane. A preferable addition amount is 1% by weight or less based on the entire epoxy resin composition.

In the composition of the present invention, a bromo compound can be blended although it is not an essential component. The bromo compound is not particularly limited as long as it is usually added as a flame retardant to the epoxy resin composition for semiconductor encapsulation, and a known compound can be used. Preferred specific examples of the bromo compound present include brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolak type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, Bromobisphenol A, decabromodiphenyl ether and the like can be mentioned, and among them, brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolak type epoxy resin are particularly preferable from the viewpoint of moldability.

Although not an essential component, an antimony compound can be added. This is usually added as a flame retardant aid to the epoxy resin composition for semiconductor encapsulation, and is not particularly limited, and a known one can be used. Preferred specific examples of the antimony compound include antimony trioxide, antimony tetroxide, and antimony pentoxide.

Further, the epoxy resin composition of the present invention includes:
Colorants such as carbon black and iron oxide, ion scavengers such as hydrotalcite, silicone rubber, olefin copolymer, modified nitrile rubber, modified polybutadiene rubber, modified silicone oil and other elastomers, heat of polyethylene and the like A release agent such as a plastic resin, a long-chain fatty acid, a metal salt of a long-chain fatty acid, an ester of a long-chain fatty acid, an amide of a long-chain fatty acid, or paraffin wax, and a crosslinking agent such as an organic peroxide can be optionally added. .

The chlorine ion content in the epoxy resin composition of the present invention is not particularly limited, but is preferably 10 ppm or less, more preferably 5 ppm or less, from the viewpoint of reliability.
ppm or less.

As a method for producing the epoxy resin composition of the present invention, the above compound is heated and kneaded, for example, at 50 to 170 ° C.
Kneading at a temperature of, for example, melt kneading using a known kneading method such as a Banbury mixer, kneader, roll, single-screw or twin-screw extruder and co-kneader, solidification, tableting if necessary Obtainable.

Next, the polyimide precursor and polyimide, which are components of the semiconductor device according to the present invention, will be described in detail.

The polyimide precursor in the present invention refers to a polymer having a structural unit represented by the general formula (I) as a main component.

Embedded image (R ₁ represents a trivalent or tetravalent organic group having at least 2 carbon atoms, R ₂ represents a divalent organic group having at least 2 carbon atoms. K represents an organic group having a double bond. And n is 1 or 2.) The polymer having a structural unit represented by the general formula (I) as a main component in the present invention has a structure represented by the general formula, Alternatively, those which can form an imide ring by dehydration with an appropriate catalyst to become a polyimide can be mentioned.

In the above general formula (I), R ₁ is at least 2
Is a trivalent or tetravalent organic group having three carbon atoms.
From the heat resistance of the polyimide, R ₁ is preferably a trivalent or tetravalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms. Preferred specific examples of R ₁ include:
Pyromellitic acid residue, 3,3 ', 4,4'-benzophenonetetracarboxylic acid residue, 3,3', 4,4'-biphenyltetracarboxylic acid residue, 3,3 ', 4,4'- Diphenylethertetracarboxylic acid residue, 3,3 ′,
4,4′-diphenylsulfonetetracarboxylic acid residue,
Examples include, but are not limited to, butanetetracarboxylic acid residues and cyclopentanetetracarboxylic acid residues.

The polyimide precursor according to the present invention comprises R ₁
May be composed of one of these, or 2
Copolymers composed of more than one kind may be used.

In the above general formula (I), R ₂ is at least 2
It is a divalent organic group having two carbon atoms.

As in the case of R ₁ , R ₂
Contains an aromatic ring or an aromatic heterocyclic ring, and has 6 carbon atoms.
~ 30 divalent groups are preferred. Preferred specific examples of R ₂ include diaminodiphenyl ether residue, diaminodiphenylsulfide residue, diaminodiphenylmethane residue, diaminodiphenylsulfone residue, phenylenediamine residue, benzidine residue, bisaminophenoxypropane residue and the like. But not limited thereto.

In the present invention, the polyimide precursor is R ₂
May be composed of one of these, or 2
Copolymers composed of more than one kind may be used.

Further, in order to improve the adhesiveness of the polyimide to other members, R ₂ should be kept within a range not lowering the heat resistance.
It is also possible to copolymerize an aliphatic group having a siloxane bond. Preferred specific examples include bis (3-aminopropyl) tetramethyldisiloxane.

In the general formula (I), n is 1 or 2.

K in the above formula (I) represents an ammonium ion having a double bond. K is an ammonium ion represented by the following formula.

[0051]

Embedded image (Where N is a nitrogen atom, H is a hydrogen atom, R ₁₁ , R ₁₂ , R
₁₃ is a monovalent organic group, and at least one has a double bond. As a specific example, R ₁₁ and R ₁₂ are an ethyl group and R
_An ammonium ion in which ₁₃ is an ethyl methacrylate group, an ammonium ion in which R ₁₁ and R ₁₂ are a methyl group and R ₁₃ is an ethyl methacrylate group, R ₁₁ and R ₁₂
Is an isopropyl group and R ₁₃ is an ethyl methacrylate ammonium ion; R ₁₁ and R ₁₂ are ethyl groups and R ₁₃ is an ethyl acrylate group; R ₁₁ and R ₁₂ are methyl groups and R ₁₃ is ethyl acrylate; Ammonium ions R ₁₁ and R ₁₂
Is an isopropyl group and an ammonium ion in which R ₁₃ is an ethyl acrylate group.

Specific examples of the polyimide precursor in the present invention include pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride And 4,4'-diaminodiphenyl ether, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, pyromellitic dianhydride and 3,3'
(Or 4,4 ')-diaminodiphenyl sulfone, pyromellitic dianhydride and 3,3', 4,4'-benzophenonetetracarboxylic dianhydride and 3,3 '(or 4,4')-diamino Diphenyl sulfone, 3,3
', 4,4'-benzophenonetetracarboxylic dianhydride and 3,3' (or 4,4 ')-diaminodiphenyl sulfone, 3,3', 4,4'-biphenyltetracarboxylic dianhydride and 3 , 3 '(or 4,4')-diaminodiphenyl sulfone, pyromellitic dianhydride and 4,
4'-diaminodiphenyl sulfide, 3,3 ', 4
4'-benzophenonetetracarboxylic dianhydride and 4,
4'-diaminodiphenyl sulfide, 3,3 ', 4
4'-biphenyltetracarboxylic dianhydride and 4,4 '
-Diaminodiphenyl sulfide, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride and paraphenylenediamine, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine, pyromellitic dianhydride and 3,3', 4,4 '-Benzophenonetetracarboxylic dianhydride and paraphenylenediamine, pyromellitic dianhydride and 3,3', 4
4'-biphenyltetracarboxylic dianhydride and paraphenylenediamine, 3,3 ', 4,4'-diphenylethertetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, 3,3', 4,4 ' Diphenylethertetracarboxylic dianhydride and paraphenylenediamine, butanetetracarboxylic dianhydride and 1,3-bis (3-aminophenoxy) benzene, cyclopentanetetracarboxylic dianhydride and 4,4'-diaminodiphenylmethane Polyimide precursor obtained by reacting a compound represented by the following formula with a polyamic acid synthesized from pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, bis (3-aminopropyl) tetramethyldisiloxane and the like The body is preferably used.

[0053]

Embedded image (N represents a nitrogen atom. R ₁₄ , R ₁₅ , and R ₁₆ are monovalent organic groups, and at least one has a double bond.) The imidation ratio of the polyimide in the present invention is not particularly limited. However, from the viewpoint of reliability, less than 100% is preferable, 90 to 99.9% is more preferable, and 95 to 99%
Is more preferred.

The chlorine ion content of the polyimide in the present invention is not particularly limited, but is preferably less than 10 ppm, more preferably 5 ppm from the viewpoint of reliability. In order to improve the adhesion between the coating film of the polyimide precursor of the present invention or the polyimide film after dehydration and the semiconductor element, an adhesion aid may be appropriately used.

As adhesion aids, oxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-
Organosilicon compounds such as methacryloxypropyltrimethoxysilane; or aluminum chelate compounds such as aluminum monoethylacetoacetate diisopropylate and aluminum tris (acetylacetonate); or titanium bis (acetylacenate)
Titanium chelate compounds and the like are preferably used.

An example of the method for producing a polyimide described in the present invention will be described. First, a diamine compound and an acid dianhydride are reacted in a solvent to obtain a polyamic acid solution which is a polymer having a structural unit represented by the general formula (I) as a main component. Next, an additive is dissolved and prepared in this solution as needed.

As the solvent used in the above production method, a polar solvent is preferably used from the viewpoint of solubility of the polymer, and an aprotic polar solvent is particularly preferable. Examples of aprotic polar solvents include N-methyl-2-pyrrolidone, N, N-
Dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphorotriamide, γ-butyrolactone and the like are preferably used.

As a method for coating a semiconductor element with polyimide in the present invention, a known technique can be used, and there is no particular limitation. An example will be described.

First, the solution of the above-mentioned polyimide precursor is applied on a semiconductor element. Examples of the application method include spin coating using a spinner, spray coating using a spray coater, dipping, screen printing, and roll coating. The coating thickness can be adjusted by the coating means, the solid content concentration of the composition, and the viscosity.
It is applied so as to be in a range of 30 μm. After the application of the polyimide precursor, a heat treatment is performed at 40 to 150 ° C. to form a polyamic acid film from which a solvent has been removed to some extent, and pattern processing is performed using a photolithographic technique. Thereafter, the coating film is subjected to heat treatment and dehydration to form a polyimide having a structural unit represented by the general formula (IV) as a main component on the semiconductor element. A preferable heat treatment temperature is 70 to 450 ° C, more preferably 150 to 400 ° C. As the heating method,
The temperature may be increased stepwise, or may be increased continuously. For the heat treatment, a commercially available ventilation oven, a hot plate, or the like can be used.

In the present invention, a semiconductor element in which a semiconductor element is partially or entirely covered with polyimide is
It is sufficient that not only the wiring side of the semiconductor element but also a part of the back and side surfaces of the element is covered with polyimide.

[0061]

Embedded image (R ₁ represents a trivalent or tetravalent organic group having at least 2 carbon atoms, and R ₂ represents a divalent organic group having at least 2 carbon atoms.) According to the epoxy resin composition of the present invention, The sealed semiconductor device refers to a semiconductor device sealed with an epoxy resin composition by a known sealing method, and examples of the sealing method include transfer molding and potting. Preferably, it is transfer molding.

[0062]

EXAMPLES Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

Examples 1 to 12 Comparative Examples 1 to 12 The raw materials shown in Table 1 were blended at the composition ratios (weight ratios) shown in Tables 3 to 6 and blended by a mixer.
The mixture was heated and kneaded for 5 minutes using a mixing roll, then cooled and pulverized to prepare an epoxy resin composition.

On the other hand, after the polyimide shown in Table 2 was formed on a 12 mm square semiconductor element having an aluminum wiring on the surface, it was mounted on a 42 alloy lead frame and subjected to wire bonding. Using this lead frame and the epoxy resin composition, a 160-pin QFP was molded at 175 ° C. for 2 minutes by low-pressure transfer molding, and then cured at 175 ° C. for 10 hours.

Example 13 The raw materials shown in Table 1 were blended at the composition ratios (weight ratios) shown in Tables 3 to 6 and blended by a mixer.
The mixture was heated and kneaded for 5 minutes using a mixing roll, then cooled and pulverized to prepare an epoxy resin composition.

On the other hand, after the polyimide shown in Table 2 was formed on an 8 mm square semiconductor element having an aluminum wiring on the surface, it was mounted on a substrate, and was then subjected to low-pressure transfer molding using an epoxy resin composition to form a circuit side. Only 175
Sealing was performed at 5 ° C. for 5 minutes. Then, it was cured at 175 ° C. for 24 hours. The dimensions of the package are 9 mm × 9 mm, and the thickness of the entire package is 0.45 μm.

Various reliability evaluations were performed by the following methods except for Example 13, and the results are shown in Tables 3 to 6.

Various reliability evaluations were performed by the following methods, and the results are shown in Tables 3 to 6.

Solder heat resistance: After humidifying for 168 hours at 85 ° C. and 85% RH using 20 160-pin QFPs,
Heat treatment was performed at 250 ° C. for 12 seconds using an IR reflow furnace. Then, the number of external cracks is checked and the number of cracked packages is regarded as a defective package. When the number is n, the value of n / 20 × 100 is used as an index of solder heat resistance, and the crack resistance (%) It is shown in the table. 0% value
Means closer to the crack resistance. In addition, the number of peeling between the polyimide and the sealing resin composition on the surface of the semiconductor element is checked, and the number of the peeled packages is regarded as a defective package. As another index indicating the property, the results are shown in the table as peel resistance (%). The closer the value is to 0%, the better the peel resistance.

Thermal shock resistance: A heat cycle test at −40 ° C. to 160 ° C. was conducted using 20 160-pin QFPs. The cycle number was 500 cycles. The number of peeling between the polyimide and the encapsulating resin composition on the surface of the semiconductor element is checked to determine whether or not the package in which the peeling has occurred is a defective package, and the number is k / 20 × 100
Is shown in the table as thermal shock resistance (%). A value closer to 0% means that the thermal shock resistance is more excellent.

Moisture resistance reliability: 20 160-pin QFPs, 120 ° C., 10 humidity using a pressure cooker
Treated at 0% for 700 hours. Thereafter, the package in which conduction failure of the aluminum wiring occurred was defined as a defective package, and the value of h / 20 × 100 is shown in the table as humidity resistance (%), where h is the number of packages. A value closer to 0% means that the moisture resistance reliability is excellent.

High-temperature reliability: After holding for 20 hours at 200 ° C. using 20 160-pin QFPs, a continuity test of a bonding wire is performed. The value of p / 20 × 100 is shown in the table as high-temperature reliability. The closer the value is to 0%, the higher the high-temperature reliability (%).

[0073]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

As shown in Tables 3 and 4, Examples 1 to
13 shows that the semiconductor device of the present invention is excellent in crack resistance and peeling resistance, which are indicators of solder heat resistance, and is excellent in any of thermal shock resistance, moisture resistance reliability, and high temperature reliability. It has high reliability.

On the other hand, as can be seen from Tables 5 and 6, the semiconductor devices not conforming to the present invention shown in Comparative Examples 1 to 11 have all of the items of peeling resistance, thermal shock resistance, moisture resistance reliability and high temperature reliability. No good value was obtained in the test, and particularly, the adhesion at the interface between the polyimide surface and the epoxy resin composition was weak, indicating that the peel resistance, thermal shock resistance, and moisture resistance reliability were low.

In Comparative Examples 10 to 11, molding was impossible due to insufficient fluidity.

[0077]

According to the present invention, it is possible to provide a semiconductor device having high reliability, which is excellent in all items of solder heat resistance, high temperature reliability, thermal shock resistance, and humidity resistance.

Continued on the front page F term (reference) 4J002 CC04X CC05X CC06X CD04W DE047 DE077 DE127 DE147 DE237 DJ017 DJ037 DJ047 EU116 EW136 EW176 EY016 FD017 FD14X FD156 GQ01 4J038 DJ021 DJ031 NA14 PB09 4M109 AA02 EB03 EB03 EB03 EB03 EB03

Claims (18)

[Claims] 1. A semiconductor device partially or wholly coated with polyimide contains an epoxy resin (A), a phenolic curing agent (B), a curing accelerator (C), and an inorganic filler (D). In a semiconductor device encapsulated with an epoxy resin composition, the polyimide is a polyimide obtained by dehydrating a polyimide precursor having a structural unit represented by the general formula (I) as a main component, and the epoxy resin ( A) a semiconductor device, wherein A) is an epoxy resin composition containing a compound represented by the general formula (II). Embedded image (R ₁ represents a trivalent or tetravalent organic group having at least 2 carbon atoms, R ₂ represents a divalent organic group having at least 2 carbon atoms. K represents an organic group containing a double bond Represents an ammonium ion having the formula: n is 1 or 2. (However, R _{2 to} R ₁₀ in the formula represent a hydrogen atom, a monovalent organic group or a halogen atom.) 2. The semiconductor device according to claim 1, wherein the imidation ratio of the polyimide is less than 100%. 3. The semiconductor device according to claim 1, wherein the content of the inorganic filler (D) is 70 to 96% by weight of the whole epoxy resin composition. 4. The semiconductor device according to claim 1, wherein the inorganic filler (D) contains silica. 5. The inorganic filler (D) has an average particle size of 5 to 25 μm.
The semiconductor device according to claim 1, wherein m is m. 6. The semiconductor device according to claim 1, wherein the maximum particle size of the inorganic filler (D) is 95 μm or less. 7. The semiconductor device according to claim 1, wherein the maximum particle size of the inorganic filler (D) is 70 μm or less. 8. The semiconductor device according to claim 1, wherein the inorganic filler (D) contains spherical silica. 9. A phenolic curing agent (B) having the general formula (III)
9. The semiconductor device according to claim 1, further comprising a compound represented by the formula: Embedded image (Where R ¹ in the formula (III) is a divalent aromatic group, R ² is a divalent aromatic group having a hydroxyl group, R ³ is a monovalent aromatic group having a hydroxyl group, R ^{1 to} R ³ May be the same or different, and n represents 0 or an integer of 1 or more.) 10. A compound represented by the general formula (III):
In (III), R ¹ is a divalent phenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a monovalent phenyl group having a hydroxyl group. 13. The semiconductor device according to claim 1. 11. A compound represented by the general formula (III):
In (III), R ¹ is a divalent biphenyl group, R ² is a divalent phenyl group having a hydroxyl group, and R ³ is a divalent biphenyl group having a hydroxyl group.
11. A monovalent phenyl group.
The semiconductor device according to any one of the above. 12. The method according to claim 1, wherein the chlorine ion content in the epoxy resin composition is 10 ppm or less.
12. The semiconductor device according to any one of 11. 13. The method according to claim 1, wherein R _{1 of the} polyimide precursor represented by the general formula (I) is represented by any of the following formulas, and n = 2. 13. The semiconductor device according to claim 1. Embedded image 14. The polyimide precursor represented by the general formula (I), wherein R ₂ is represented by any of the following formulas, and n = 2. Semiconductor device. Embedded image (However, R _a and R _b represent a fluorine atom, a hydrogen atom, a monovalent hydrocarbon group, or a monovalent hydrocarbon group containing a fluorine atom.) 15. The semiconductor device according to claim 1, wherein the polyimide obtained by dehydrating the polyimide precursor represented by the general formula (I) has a chlorine ion content of less than 10 ppm. . 16. The content of the inorganic filler (D) is from 85 to 95.
The semiconductor device according to claim 1, wherein the content is% by weight. 17. The semiconductor device according to claim 1, wherein only the circuit forming surface side of the semiconductor element is sealed with the epoxy resin composition, and the back surface is not sealed. 18. The semiconductor device according to claim 1, wherein the thickness of the entire package is less than 0.5 μm.