JP2008297373A - Underfill material comprising liquid epoxy resin composition, and flip chip type semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underfill material having low viscosity, excellent in workability and forming a cured material excellent in close adhesion with the surface of a silicon chip, especially with a photosensitive polyimide resin or silicon nitride film, and a flip chip type semiconductor device encapsulated with the underfill material. <P>SOLUTION: This underfill material comprises (A) a bisphenol A type epoxy resin having 40 to 60°C melting point and also having <360 weight-average molecular weight, (B) an aromatic amine-based curing agent, (C) an inorganic filler treated with a silane-coupling agent, and (D) a liquid epoxy resin composition containing a stress relaxation agent, and has 0.1 to 0.3 Pa s viscosity at 90°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an element of a silicon chip having a low viscosity, a very good workability, and a photosensitive polyimide, a silicon nitride film, an oxide film, etc., for sealing a semiconductor, particularly a flip chip type semiconductor device. The present invention relates to an underfill material having very good adhesion to a surface, and a flip chip type semiconductor device sealed with the underfill material.

  High-density mounting of high-performance, highly integrated, small, and thin semiconductor packages is performed in cellular phones, liquid crystals, plasma televisions, notebook computers, and the like. Among them, flip chip mounting is considered to be a powerful semiconductor mounting technology because the mounting area can be mounted to the same size as the semiconductor chip with high density.

  At this time, in order to improve the connection reliability of the solder joint portion of the mounting substrate, an underfill material is filled between the substrate and the chip (gap).

  And in order to improve the adhesiveness with respect to the silicon chip surface which has a photosensitive polyimide resin, a silicon nitride film, etc., it is necessary to improve the wettability and chemical interaction to a chip surface.

As flip chip semiconductor devices are becoming more highly integrated, the gap between the gaps becomes narrower, and the sealing resin needs to be highly fluid in order to efficiently enter the gap in a short time. is there.
Also, the injection of the underfill material is usually performed in a state of being heated to a temperature of about 60 to 90 ° C. (working environment temperature), and how to reduce the viscosity of the underfill material under the working environment temperature. Was an issue.
For example, it is usually common to add a solvent or reactive diluent to reduce the viscosity. However, in this case, since the solvent and the reactive diluent are released into the atmosphere by heating, there is a concern about the influence of the environment.

For this reason, as a recent environmentally friendly product, a solvent-free underfill material having almost no solvent volatilization during work and a low viscosity has been developed.
For example, a liquid epoxy resin in which an aromatic amine curing agent and an inorganic filler are mixed is known. (For example, Patent Document 1)
In this case, although no solvent was used, the viscosity at the working environment temperature was still high, and the penetration was not satisfactory.

JP 2004-331908 A

  The present invention has been made in view of the above circumstances, and improves the adhesion and fluidity to the surface of a silicon chip such as a photosensitive polyimide resin or a silicon nitride film, and can be a sealing material for a good semiconductor device, Another object of the present invention is to provide a flip chip type semiconductor device sealed with this underfill material.

  As a result of intensive studies to achieve the above object, the present inventor has obtained (A) a bisphenol A type epoxy resin having a melting point of 40 to 60 ° C. and a weight average molecular weight of less than 360, (B) An underfill material comprising a liquid epoxy resin composition containing an aromatic amine-based curing agent, (C) an inorganic filler treated with a silane coupling agent, and (D) a stress relaxation agent, and having a viscosity at 90 ° C. By using an underfill material having a thickness of 0.1 to 0.3 Pa · s, the underfill material is excellent in fluidity and excellent in workability because no solvent is used, and photosensitive polyimide. It has been found that the adhesion and workability to the surface of a silicon chip having a resin, a silicon nitride film, etc. are improved, and the present invention has been completed.

That is, the present invention provides a flip chip type semiconductor device sealed with the underfill material in addition to the following underfill material.
[1] At least
(A) a bisphenol A type epoxy resin having a melting point of 40 to 60 ° C. and a weight average molecular weight of less than 360,
(B) an aromatic amine curing agent,
(C) an inorganic filler that has been treated with a silane coupling agent;
(D) An underfill material comprising a liquid epoxy resin composition containing a stress relaxation agent, wherein the underfill material has a viscosity at 90 ° C. of 0.1 to 0.3 Pa · s. Fill material.
[2] The underfill material according to [1], wherein the (B) aromatic amine curing agent is an aromatic amine compound represented by the following general formula (1).

（式中、Ｒ^１〜Ｒ^３は独立に置換もしくは無置換の炭素数１〜６の一価炭化水素基、ＣＨ_３Ｓ−及びＣ_２Ｈ_５Ｓ−から選ばれる基である。）

(In the formula, R ^{1 to} R ³ are groups independently selected from a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, CH ₃ S— and C ₂ H ₅ S—.)

[3] The underfill material according to [1] or [2], wherein the silane coupling agent is an epoxy silane coupling agent.
[4] A flip chip type semiconductor device sealed with the underfill material according to any one of [1] to [3].

  The epoxy resin used in the underfill material of the present invention has a low viscosity under the working environment temperature compared to the conventional epoxy resin, so it is possible to reduce the viscosity as an underfill material, and thus, particularly a narrow gap flip In the chip type semiconductor device, it is possible to improve the penetration property, and the connection reliability between the substrate and the chip can be improved.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. The scope of the present invention includes modifications, improvements, and the like as appropriate to the following embodiments.

  The underfill material of the present invention comprises at least (A) a bisphenol A type epoxy resin having a melting point of 40 to 60 ° C. and a weight average molecular weight of less than 360, (B) an aromatic amine curing agent, (C It consists of a liquid epoxy resin composition containing an inorganic filler treated with a silane coupling agent and (D) a stress relaxation agent.

As said (A) component used for the underfill material of this invention, melting | fusing point is 40-60 degreeC, and a weight average molecular weight is less than 360.
This is because if the melting point is less than 40 ° C., moisture in the air is easily adsorbed and the storage stability of the epoxy resin is deteriorated. This is because if the melting point exceeds 60 ° C., solidification is likely to occur during underfill production, and workability is deteriorated.
This is because when the weight average molecular weight is 360 or more, the viscosity of the underfill material is not sufficiently lowered at the working environment temperature, and the penetration property is deteriorated.
Examples of the component (A) include YL6810 manufactured by Japan Epoxy Resin Co., Ltd.

  The total chlorine content in the component (A) is preferably 1,500 ppm or less, and more preferably 1,000 ppm or less. Moreover, it is preferable that the extraction water chlorine in 20 hours in the 50% epoxy resin density | concentration at 100 degreeC is 10 ppm or less. If the total chlorine content exceeds 1,500 ppm or the extracted water chlorine exceeds 10 ppm, the reliability of the semiconductor element, particularly the moisture resistance, may be adversely affected.

  Next, the aromatic amine curing agent (B) used in the present invention is, for example, xylenediamine, diaminodiphenylmethane, 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, phenylenediamine, dimethyltoluene. Diamine, diethyltoluenediamine, dimethylthiotoluenediamine, 3,3′-diethyl-4,4′-diaminophenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminophenylmethane, 3 , 3 ′, 5,5′-tetraethyl-4,4′-diaminophenylmethane, 2,4-diaminotoluene, 1,3-diaminobenzene, metaphenylenediamine, benzidine, diaminodiphenyl ether, 4,4′-thiodianiline, 4,4'-bis (o-toluidine), orthophenylenediamine, bis ( 3,4-diaminophenyl) sulfone, 4-chloro-o-phenylenediamine and the like. These may be used alone or in combination.

  Among them, the aromatic amine-based curing agent represented by the following general formula (1) has a low viscosity and a long pot life, and is excellent in mechanical properties, electrical properties, heat resistance properties, and chemical resistance properties of the cured product. It is preferable to use this curing agent because it has excellent adhesion to the surface of a silicon chip having a photosensitive polyimide resin or a silicon nitride film.

（式中、Ｒ^１〜Ｒ^３は独立に置換もしくは無置換の炭素数１〜６の一価炭化水素基、ＣＨ_３Ｓ−及びＣ_２Ｈ_５Ｓ−から選ばれる基である。）

(In the formula, R ^{1 to} R ³ are groups independently selected from a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, CH ₃ S— and C ₂ H ₅ S—.)

Here, as the monovalent hydrocarbon group for R ^{1 to} R ³ , those having 1 to 6 carbon atoms, particularly 1 to 3 carbon atoms are preferable, and a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Alkyl groups such as tert-butyl group and hexyl group, vinyl groups, allyl groups, propenyl groups, butenyl groups, alkenyl groups such as hexenyl groups, phenyl groups, etc., and some or all of hydrogen atoms of these hydrocarbon groups And halogen-substituted monovalent hydrocarbon groups such as a fluoromethyl group, a bromoethyl group, and a trifluoropropyl group substituted with a halogen atom such as chlorine, fluorine, and bromine.

  Specific examples of the aromatic amine compound represented by the general formula (1) include diethyltoluenediamine, dimethylthiotoluenediamine, and dimethyltoluenediamine.

  In addition, as for the compounding quantity of the said (B) component, it is preferable that the compounding molar ratio of the (B) component with respect to the said (A) component is the range of 0.2-0.5. This is because if the blending molar ratio is less than 0.2, unreacted glycidyl groups remain, and mechanical properties and heat resistance properties may be deteriorated. Conversely, if it exceeds 0.5, the cured product becomes hard and brittle, and the stress relaxation property may be inferior. From the viewpoint of mechanical properties / heat resistance properties and stress relaxation properties, it is preferably in the range of 0.25 to 0.3.

On the other hand, the inorganic filler (C) used in the present invention is treated with a silane coupling agent. The reason why the surface treatment is performed with the silane coupling agent is that the affinity with the epoxy resin is increased, which contributes to suppression of filler aggregation, improvement of moisture resistance and heat resistance, and improvement of resin fluidity.
As the inorganic filler itself, conventionally known inorganic fillers can be used for the purpose of reducing the linear expansion coefficient. Specific examples include fused silica, synthetic silica, crystalline silica, alumina, boron nitride, ticker aluminum, ticker silicon, magnesia, magnesium silicate, aluminum, and the like. Among them, spherical fused silica is desirable for reducing the viscosity.
In addition, as the types of coupling agents, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ- (2- Aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylamino) Ethyl) -γ-aminopropylmethoxysilane / hydrochloride, aminosilane, methyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, vinyltris (β- Toxiethoxy) silane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, methyltrichlorosilane, dimethyldichlorosilane and the like can be used, but 2- (3,4) because of high adhesion efficiency. It is desirable to use -epoxycyclohexyl) ethyltrimethoxysilane.

  As a compounding quantity of an inorganic filler (C), it is preferable to set it as 50-500 weight part with respect to a total of 100 weight part of said (A) component and said (B) component, More preferably, it is 100-400 weight part. Range. If it is less than 50 parts by weight, the expansion coefficient is large and there is a risk of inducing the occurrence of cracks in the cold test. Moreover, when it exceeds 500 weight part, there exists a possibility that a viscosity may become high and the thin film penetration property may be brought about.

The flow characteristics of the underfill material greatly depend on the particle size distribution of the filler. In general, a filler having a wider distribution and a larger particle size has a lower viscosity of the composition and better fluidity. However, if a filler containing a large particle size is used for the purpose of reducing the viscosity, the filler having a large particle size settles during curing, and the linear thermal expansion coefficient in the gap becomes non-uniform, which is not preferable in terms of connection reliability. . Since the underfill material needs to flow between the substrate and the chip (gap), the filler particle size needs to be smaller than the gap, and more preferably the maximum particle size is about 50% of the gap or less. On the other hand, if the particle size is too small, the specific surface area increases and the viscosity increases, so that the fluidity cannot be ensured. For this reason, in order to satisfy these conditions, a filler having an average particle size of 0.5 μm to 15 μm and a maximum particle size of 50 μm or less is preferable.
From the viewpoint of connection reliability and fluidity, it is more preferable to use a filler having a particle size distribution with an average particle size of 2 to 10 μm and a maximum particle size of 25 μm or less. Moreover, a filler may be used individually by 1 type, or 2 or more types may be mixed and used for it.

The (D) stress relaxation agent that can be used in the present invention is not particularly limited. For example, elastomers such as silicone rubber, butadiene / acrylonitrile rubber, butadiene rubber, styrene / butadiene rubber, silicone-based epoxy resins and polyphenol compounds Or the reaction product with a phenol resin, etc. can be mentioned. These can be arbitrarily selected and used alone or in combination of two or more.
(D) It is preferable that the compounding quantity of a stress relaxation agent is 10-50 mass parts with respect to 100 mass parts of said (A) component. If it is less than 10 parts by mass, it is not preferable in that the stress relaxation property is reduced, and if it exceeds 50 parts by mass, it is not preferable in that the mechanical strength for protecting the bump is reduced. More preferably, it is the range of 10-40 mass parts at the point of stress relaxation property and mechanical strength.

  If necessary, the underfill material of the present invention may further contain a pigment such as carbon black, a dye, an antioxidant, and other additives as long as the object of the present invention is not impaired.

  In the underfill material of the present invention, for example, an epoxy resin, an aromatic amine-based curing agent, an inorganic filler, a stress relaxation agent, and other additives as necessary may be simultaneously or separately, and may be heat-treated as necessary. While adding, it can be obtained by stirring, dissolving, mixing and dispersing. The apparatus for mixing, stirring, dispersing and the like is not particularly limited, and a lykai machine, a three roll, a ball mill, a planetary mixer, a bead mill and the like equipped with a stirring and heating device can be used. Moreover, you may use combining these apparatuses suitably.

In particular, in the present invention, the viscosity of the underfill material needs to be 0.1 to 0.3 Pa · s at 90 ° C. under the working environment temperature. If it is less than 0.1 Pa · s, the underfill material tends to spread around the chip, so that it adheres to the connection part of other adjacent components, and may deteriorate the mechanical strength and heat resistance. This is because if the pressure exceeds 3 Pa · s, the viscosity of the underfill material is not sufficiently lowered at the working environment temperature, and the penetration property is deteriorated.
In addition, since the working environment temperature is usually around 90 ° C. for the underfill agent, the viscosity of the underfill material is defined by the viscosity at 90 ° C. in the present invention.

  Next, a flip chip type semiconductor device will be described.

  Here, as a flip chip type semiconductor device used in the present invention, for example, as shown in FIG. 1, a semiconductor chip 3 is usually mounted on a wiring pattern surface of a substrate 1 via a plurality of bumps 2. The underfill material 4 can be filled in the gap between the substrate 1 and the semiconductor chip 3 (the gap between the bumps 2). As the substrate 1, for example, a flame-resistant glass base epoxy resin laminate (FR-4 substrate) can be used.

  When using the underfill material which consists of a liquid epoxy resin composition of this invention, it is preferable that the expansion coefficient below the glass transition temperature of the hardened | cured material is 20-40 ppm / degreeC. As a means for obtaining such an expansion coefficient, for example, a method of blending 100 to 400 parts by weight of the inorganic filler with respect to 100 parts by weight of the total of the epoxy resin and the curing agent can be employed.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited to the following Example.
In addition, about the epoxy resin solid at normal temperature, melting | fusing point and number average molecular weight were evaluated, and about the underfill material of an Example and a comparative example, 25 degreeC viscosity, 90 degreeC viscosity, penetration | invasion property, void resistance, adhesive force The flip chip type semiconductor device sealed with the underfill material was evaluated for the conductivity (hereinafter referred to as “conductivity”) of the solder connection part after the thermal cycle test. The results are shown in Table 1.

[Melting point]
A differential scanning calorimeter (DSC3100, manufactured by Mac Science Co., Ltd.) was used, and the measurement was performed at a heating rate of 10 ° C./min.

[Number average molecular weight]
Using a gel permeation chromatography measuring device (HLC8220GPC, manufactured by Tosoh Corp.) and a column (4 TSKgel Super HZM-M, manufactured by Tosoh Corp.), it was determined as a value in terms of polystyrene measured by the GPC method.

[25 ° C viscosity]
Using an E-type rotational viscometer, the viscosity at 25 ° C. was measured at a rotational speed of 20 rpm.

[90 ° C viscosity]
Using a rheometer (model name DAR-100, manufactured by REOLOGICA), the temperature was raised at a speed of 10 ° C./min under a shearing stress of 5.0 Pa and held for 500 seconds after reaching 90 ° C. The average value of the viscosity at 90 ° C. was calculated.

[Invasion]
A spacer of about 50 μm is provided between two 76 mm × 26 mm glass slides and placed on a hot plate heated at 90 ° C. The underfill material was melted and invaded into the generated gap, and the time when the underfill material filled the gap by 10 mm was measured.

[Void resistance]
A spacer of about 50 μm is provided between two 76 mm × 26 mm glass slides, the underfill material is penetrated and cured in the generated gap, and the presence or absence of voids within 10 mm from the entry start point is visually confirmed. Judged by criteria.
Good: No voids visible visually Bad: Visually visible voids

[Adhesive strength]
An underfill material is put on a silicon nitride surface of a semiconductor chip having an FR-4 substrate or a silicon nitride film by using a mold and cured at 150 ° C. for 2 hours, and a cylindrical test piece having a diameter of 2 mm and a height of 2 mm. Was made. After curing, the shear adhesion of the obtained specimen was measured.

[Conductivity]
As shown in FIG. 1, a 4.2 mm × 4.6 mm × 0.3 mm semiconductor chip was connected to a 20 mm × 20 mm FR-4 substrate via bumps. An underfill material was injected between the semiconductor chip and the FR-4 substrate and cured at 150 ° C. for 2 hours to obtain a test piece. The resistance value of this test piece was measured with an impedance analyzer 4194A (manufactured by Yokogawa, Hewlett-Packard Co.) and designated as “initial resistance value”.
Next, a thermal cycle test (−40 ° C. × 15 minutes × 120 ° C. × 15 minutes, 1000 cycles) of this test piece was performed. The resistance value of the test piece after the test was measured in the same manner. This measured value was designated as “post-test measured value”.
The rate of increase in resistance value was calculated by the following general formula (2), and the conductivity was evaluated according to the following criteria.
Good: Resistance value increase rate is less than 10% Defective: Resistance value increase rate is 10% or more

Synthesis of stress relaxation agent 1g of 1,8-diazabicyclo [5.4.0] unde-7-ene was added as a catalyst to 100g of silicone epoxy resin (TSL 9906, manufactured by Toshiba Silicone) and 27g of bisphenol F (hydroxyl equivalent 100). And allowed to react at 180 ° C. for 3 hours under a nitrogen stream. This reaction product was used as a stress relaxation agent.

Example 1
90 parts by mass of bisphenol A type epoxy resin (epoxy equivalent 170, melting point 45 ° C.), 190 parts by mass of fused silica (average particle size 3.2 μm), 25 parts by mass of diethyltoluenediamine, silane coupling agent (2- (3,4) -Epoxycyclohexyl) ethyltrimethoxysilane) 2.3 parts by weight and 10 parts by weight of a stress relaxation agent were mixed and uniformly kneaded with three rolls to obtain an underfill material.

Example 2
An underfill material was obtained by mixing in the same manner as in Example 1 except that the silane coupling agent was changed to 3-glycidoxypropyltrimethoxysilane.

Comparative Example 1
An underfill material is obtained by mixing in the same manner as in Example 1 except that the epoxy resin is changed to a liquid bisphenol A type epoxy resin (epoxy equivalent 190, product name JER 828, manufactured by Japan Epoxy Range) at 25 ° C. It was.

Comparative Example 2
Except for changing the curing agent from diethyltoluenediamine to 84 parts by mass of acid anhydride (product name MHAC-P, manufactured by Hitachi Chemical Co., Ltd.) and 15 parts by mass of curing accelerator (product name HX-3722, manufactured by Asahi Kasei Chemicals). Were mixed in the same manner as in Example 1 to obtain an underfill material.

Comparative Example 3
An underfill material was obtained by mixing in the same manner as in Example 1 except that the epoxy resin was changed to a bisphenol F type epoxy resin (epoxy equivalent 170, product name JER807, manufactured by Japan Epoxy Range).

Comparative Example 4
An underfill material was obtained by mixing in the same manner as in Example 1 except that the epoxy resin was changed to a naphthalene type epoxy resin (epoxy equivalent 150, product name HP-4032D, manufactured by Japan Epoxy Resin Co., Ltd.).

As is clear from Table 1, it can be understood that in Comparative Example 1, Comparative Example 3, and Comparative Example 4, the 90 ° C. viscosity is high, so that the penetration is poor and the void resistance and conductivity are poor. Moreover, since the acid anhydride is used for the hardening | curing agent in the comparative example 2, it turns out that it is inferior to the adhesiveness with respect to a silicon nitride film, and electroconductivity.
On the other hand, in Example 1 and Example 2, it can be understood that the viscosity at 90 ° C., the adhesive strength, the penetration property, and the void resistance are good, and the conductivity is also excellent.

It is sectional drawing which shows an example of the flip chip type semiconductor device sealed using the underfill material of this invention.

Explanation of symbols

1 Substrate 2 Bump 3 Semiconductor chip 4 Underfill material

Claims (4)

at least,
(A) a bisphenol A type epoxy resin having a melting point of 40 to 60 ° C. and a weight average molecular weight of less than 360,
(B) an aromatic amine curing agent,
(C) an inorganic filler that has been treated with a silane coupling agent;
(D) An underfill material comprising a liquid epoxy resin composition containing a stress relaxation agent, wherein the underfill material has a viscosity at 90 ° C. of 0.1 to 0.3 Pa · s. Fill material. (B) The underfill material according to claim 1, wherein the aromatic amine curing agent is an aromatic amine compound represented by the following general formula (1).

(In the formula, R ^{1 to} R ³ are groups independently selected from a substituted or unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, CH ₃ S— and C ₂ H ₅ S—.) The underfill material according to claim 1 or 2, wherein the silane coupling agent is an epoxy silane coupling agent. A flip chip type semiconductor device sealed with the underfill material according to any one of claims 1 to 3.

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