JP2002097254A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which is a liquid sealant excellent in temperature cycle, permeation, fillet, quick curability, moisture resistant reliability or the like. SOLUTION: In a liquid epoxy resin composition at room temperature, which uses an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components. The epoxy resin composition contains at least a bisphenol A epoxy resin or the like as an epoxy resin, and the same contains an acid anhydride shown by the formula (A) as a curing agent, and amine adduct particles or the like as a curing accelerator. In addition, the same contains 10-60 vol.% by true specific gravity conversion, spherical amorphous silica or the like whose maximum diameter of the particle is 0.5-20 μm, to the epoxy resin composition whole quantity as an inorganic filler. (In the formula, R1-R3 is respectively a 1-6C hydrocarbon group or hydrogen atom, and the total of the number of carbon atoms in the R1-R3 is 6, the total of the number of hydrogen atoms in the R1-R3 is 13).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flip-chip mounting method for minimizing the mounting area of a semiconductor chip on a circuit board by electrically connecting the semiconductor chip and the circuit board using metal bumps. The present invention relates to an epoxy resin composition used and a semiconductor device manufactured using the epoxy resin composition.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor chip packaged with a resin or the like is mounted on a circuit board, soldering has been widely used. A bare chip mounting that directly mounts on a circuit board without housing in a package has been devised. In the early stage of the bare chip mounting, a method called chip on board (COB) was adopted. That is, in this method, the back side of the circuit surface of the semiconductor chip is bonded and fixed to the circuit board, and the circuit of the semiconductor chip and the electrode of the circuit board are wire-bonded with a metal wire such as a gold wire. The wire is sealed with a resin.

[0003] Thereafter, in order to further minimize the mounting area of the semiconductor chip on the circuit board, a method called flip-chip mounting has appeared. In this method, a circuit of a semiconductor chip and an electrode of a circuit board are electrically connected using metal bumps. Specifically, for example, a vapor deposition film of an adhesion metal or a diffusion preventing metal is formed on a terminal electrode of a circuit of a semiconductor chip in advance, and a solder bump electrode is formed thereon by plating. The protruding electrodes thus formed are metal bumps. Then, the semiconductor chip is face-down with the metal bumps facing the electrodes of the circuit board, and heated to a high temperature, so that the solder for forming the metal bumps is fused to the electrodes of the circuit board, and the semiconductor chip is mounted on the circuit board. It is to do. Such a mounting method is considered to be an effective method because the mechanical strength after connection by the metal bumps is strong and the connection can be performed collectively (for example, Industrial Research Council, published on January 15, 1980). , Japan Microelectronics Association, "IC packaging technology").

Further, C4 (Controlled Collapse Chip Con
nection) for flip-chip mounting
As shown in U.S. Pat. No. 5,121,190 and Japanese Patent Application Laid-Open No. 6-61303, the reliability of a solder joint that connects a semiconductor chip to a circuit board (described as a chip carrier or the like in the above publication) is ensured. To this end, there has been proposed a solder interconnect structure in which a gap between a semiconductor chip and a circuit board is filled with a sealing material (described as an encapsulant in the above-mentioned publication) and a method of manufacturing the same. .

Further, stud bump bonding (SB)
Regarding the mounting method referred to as B), see JP-A-11-35
As shown in Japanese Patent No. 4575, when a semiconductor chip (described as a semiconductor element in the above-mentioned publication) is mounted on a circuit board, a protruding electrode formed of gold of the semiconductor chip is bonded to a conductive adhesive containing silver powder. After connecting to the connection electrode of the circuit board via the agent, a liquid sealing material (described as a sealing resin in the above-mentioned publication) is caused to penetrate into the gap between the semiconductor chip and the circuit board. A semiconductor device (in the above-mentioned publication, referred to as a semiconductor unit) and a method of mounting a semiconductor chip in which a stopper is cured has also been proposed.

[0006] In these prior arts, the main reason for requiring a liquid sealing material is to improve the temperature cyclability of a semiconductor device in which a semiconductor chip is mounted on a circuit board. Normally, the thermal expansion coefficient of a semiconductor chip and that of a circuit board are different. Therefore, under actual conditions of use, thermal cycling is applied near the metal bumps. is there. Therefore, in an unsealed semiconductor device in which a sealing material is not used, the stress generated in this manner cannot be dispersed, and cracks and the like are easily generated in the metal bumps, and destruction occurs. On the other hand, in a semiconductor device sealed by using a sealing material, since this sealing material has a function of dispersing stress,
This prevents the destruction of the metal bump.

[0007]

However, as the objects and applications of flip-chip mounting have expanded, in addition to the above-mentioned temperature cycling properties, sealing materials such as infiltration properties, fillet properties, rapid curing properties, moisture resistance reliability, etc. Demands for excellent performance have been increasing.

[0008] Here, the penetrability is evaluated by the time for the sealing material to penetrate into the gap between the semiconductor chip and the circuit board, and it can be said that the shorter the time, the better the penetrability.
Excellent fillet property means that the fillet is formed naturally from the side of the semiconductor chip to the circuit board, and excellent fast-curing property means that the sealing material cures in a short time and is necessary. This means that reliability can be achieved.

Further, the above-mentioned Japanese Patent Application Laid-Open No. 11-354575
In the SBB disclosed in Japanese Unexamined Patent Publication, a special sealing material is required, and this sealing material may not be able to secure electrical connection reliability unless it takes a long time of about 4 hours for curing. is there. Accordingly, there is a need for a sealing material that can be cured in a short time in SBB and that ensures electrical connection reliability after curing.

[0010] As described above, the performances such as the temperature cycling property, the infiltration property, the fillet property, the rapid curing property, the moisture resistance reliability, and the electrical connection reliability after curing are all low-cost and high-performance flip-chip mounting. It is necessary for application.

The present invention has been made in view of the above points, and has been found to be excellent in temperature cyclability, penetrability, fillet properties, rapid curing properties, moisture resistance reliability, and to expand the applicable field of flip chip mounting. An object of the present invention is to provide an epoxy resin composition for sealing capable of securing electrical connection reliability, and a semiconductor device manufactured using the epoxy resin composition.

[0012]

The epoxy resin composition according to claim 1 of the present invention is a liquid epoxy resin composition at room temperature, which comprises an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components. Wherein the epoxy resin contains at least one of a bisphenol A epoxy resin, a bisphenol F epoxy resin, and a naphthalene epoxy resin, and as a curing agent, an acid anhydride represented by the following formula (A). As a curing accelerator, containing a compound having an imidazole skeleton as a nucleus and containing at least one of fine spherical particles obtained by coating the periphery of the nucleus with a coating of a thermosetting resin, or amine adduct particles, As a filler, spherical amorphous silica having a maximum particle size of 0.5 to 20 μm, or a maximum particle size of 0.5 to 10 μm
m, wherein at least one of aluminas is contained in an amount of 10 to 60% by volume in terms of true specific gravity based on the total amount of the epoxy resin composition.

[0013]

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A second aspect of the present invention is characterized in that, in the first aspect, a bisphenol A type epoxy resin having an epoxy equivalent of 180 or less is used as the epoxy resin.

According to a third aspect of the present invention, in the first or second aspect, the ratio between the epoxy equivalent of the epoxy resin and the curing agent equivalent of the curing agent is 100: 60 to 100: 120. is there.

The invention of claim 4 is characterized in that in any one of claims 1 to 3, a silane coupling agent or a titanate coupling agent is used as the coupling agent.

Further, the invention according to claim 5 is characterized in that, in any one of claims 1 to 4, a compound represented by the following formula (B) or a compound represented by the following formula (C) is used as an additive:
It is characterized by containing 0.01 to 1% by mass based on the total amount of the epoxy resin composition.

[0018]

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According to a sixth aspect of the present invention, in a semiconductor device manufactured by bonding a metal bump formed on a semiconductor chip to a circuit board, the semiconductor chip is flip-chip mounted on the circuit board. A gap formed between the semiconductor chip and the circuit board via the metal bump is filled with the epoxy resin composition according to any one of claims 1 to 5, and a fillet portion is formed from an end of the semiconductor chip to the circuit board. And heating and curing the epoxy resin composition at 110 to 180 ° C.

According to a seventh aspect of the present invention, in the sixth aspect, a conductive paste comprising a metal powder, a thermoplastic resin, and an organic solvent is applied to the surface of the circuit board and dried.
A semiconductor chip is mounted and manufactured on a circuit board by joining a metal bump formed of gold to the circuit board via the conductive paste.

[0021]

Embodiments of the present invention will be described below.

The epoxy resin composition according to the present invention contains an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components and is liquid at room temperature. Hereinafter, the details of each of the above components will be described in order.

In the present invention, as the epoxy resin, bisphenol A type epoxy resin obtained by reacting bisphenol A with epichlorohydrin, bisphenol F type epoxy resin obtained by reacting bisphenol F with epichlorohydrin, 1,6-dihydroxynaphthalene At least one of the naphthalene type epoxy resins obtained by the reaction with epichlorohydrin is used. However, if the above epoxy resin is used, as an epoxy resin other than these,
A novolak type epoxy resin, an alicyclic epoxy resin, a bisphenol S type epoxy resin, an epoxy resin of dicyclopentadiene phenolic polymer, an epoxy resin containing nitrogen in a molecule, and the like can also be used in combination.

As the epoxy resin, it is particularly preferable to use a bisphenol A type epoxy resin having an epoxy equivalent of 180 or less. When such a bisphenol A type epoxy resin is contained in the epoxy resin composition, the balance of the viscosity, curability, heat resistance of the cured product, moisture absorption, etc. of the epoxy resin composition is well maintained. is there. The epoxy equivalent was 180 or less,
If it is in this range, the content of the epoxy resin having a high molecular weight in a linear chain becomes extremely low, the viscosity of the epoxy resin composition can be lowered, and high fluidity can be exhibited. This is because the heat resistance of the cured product does not decrease.

A pure bisphenol A type epoxy resin is bisphenol A diglycidyl ether, which has a molecular weight of 340. Since this pure product has two epoxy groups per molecule, the epoxy equivalent is 170, which is half the molecular weight. Therefore, the epoxy equivalent of the bisphenol A type epoxy resin is 170
Since this is only possible, the practical lower limit is 170.

In the present invention, as the curing agent, an acid anhydride represented by the above formula (A) is used. Here, in the formula, R1 to R3 each represent a hydrocarbon group having 1 to 6 carbon atoms or a hydrogen atom, and the total number of carbon atoms of these groups is 6, and the total number of hydrogen atoms is 13. . Such an acid anhydride is a compound of the monoterpene represented by the molecular formula C ₁₀ H ₁₆ having three carbon-carbon double bonds in one molecule and two of the double bonds being conjugated (hereinafter referred to as triene). Of monoterpene) and maleic anhydride by a 6-membered cyclization by a Diels-Alder (Diels-Alder) reaction. Therefore, R1 to R3 bonded to the 6-membered ring can be considered to be derived from triene monoterpene. The triene monoterpene is a monoterpene that does not have a cyclic structure.

For example, triene monoterpenes include:
The myrcene represented by the following formula (D) can be mentioned, and this myrcene reacts with maleic anhydride as shown by the following chemical reaction formula (I) to give the formula (A-1) (formula (A) The acid anhydride represented by the specific example) is produced. Here, of the carbon atoms forming the 6-membered ring of the acid anhydride, four are numbered from 3 to 6 for convenience as shown in the formula, and hereinafter, for example, carbon atoms numbered 3 The atom is expressed as the third carbon atom, and each carbon atom is specified. As shown in the formula (A-1), R1
Is a hydrocarbon group bonded to the carbon atom at the 4-position, and R1 contains 6 carbon atoms and 11 hydrogen atoms. At this time, R2 and R3 are both limited to a hydrogen atom, but these R2 and R3 are in the 3-, 5-, or 6-position.
Can be considered as any hydrogen atom attached to the carbon atom at the position. Therefore, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0028]

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As another triene monoterpene different from the above, there may be mentioned the ocimene β-formula represented by the following formula (E). This ocimene β-form is represented by the following chemical reaction formula (II). Reacts with maleic anhydride to produce an acid anhydride represented by the formula (A-2) (another specific example of the formula (A)). As shown in the formula (A-2), R1 and R2 are both hydrocarbon groups, which are respectively bonded to the 3- and 4-position carbon atoms, and R1 and R2 are
2 and the total number of carbon atoms is 6, and the number of hydrogen atoms is 12 in total. At this time, R3 is limited to a hydrogen atom, and this R3 can be considered as any hydrogen atom bonded to the 3-, 5-, or 6-position carbon atom. Therefore, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0030]

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Further, as another triene monoterpene different from the above, there can be mentioned those represented by the following formula (F), which is represented by the following chemical reaction formula (III).
Reacting with maleic anhydride as shown by the formula (A-
3) An acid anhydride represented by (another specific example of the formula (A)) is produced. As shown in the formula (A-3), R
Each of 1 to R3 is a hydrocarbon group,
It is bonded to the 4th and 6th carbon atoms, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0032]

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The above three examples show the case where one, two, and three hydrocarbon groups are used as R1 to R3, and the terpene derived from a natural product is a triene (with one carbon-carbon double bond). However, it is actually difficult to limit the structure to one as a pure product. Therefore, the acid anhydride represented by the formula (A) used in the present invention is not limited to those produced from the above-mentioned triene monoterpene as a specific example.

When the epoxy resin composition contains the acid anhydride represented by the above formula (A) as a curing agent, the flip-chip mounting has a temperature cycle property,
Filler properties, moisture resistance reliability, and connection reliability can be suitably exhibited. Although the reason for this is not clear at present, it is presumed that the structure of the monoterpene interacts with and affects other components in the epoxy resin composition. Therefore, it is impossible to realize each of the above-mentioned characteristics only with conventional typical liquid acid anhydrides such as methylhexahydrophthalic anhydride (MHHPA) and methyltetrahydrophthalic anhydride (MTHPA).
It is necessary that the acid anhydride represented by the formula (A) be contained in the epoxy resin composition, and if this is satisfied, the acid anhydride is contained in one molecule such as MHHPA and MTHPA. An acid anhydride having one or more acid anhydride groups can also be used as a curing agent.

Here, the molar ratio of the stoichiometric reactive group between the epoxy resin and the curing agent, that is, the ratio (equivalent ratio) between the epoxy equivalent and the curing agent equivalent is 100: 60 to 100: 120.
And more preferably 100: 75
１００100: 100. When the value is outside this range, that is, when the curing agent equivalent of the curing agent is less than 60 with respect to the epoxy equivalent of 100 of the epoxy resin, the epoxy resin composition becomes difficult to cure, or the heat resistance of the cured product even after curing. And the strength of the cured product may be reduced.
Conversely, when the curing agent equivalent exceeds 120, the heat resistance of the cured product may be reduced, the adhesive strength after curing may be reduced, and the moisture absorption of the cured product may be increased. In the present invention, since an acid anhydride is used as a curing agent, the curing agent equivalent is also referred to as an acid anhydride equivalent.

In the present invention, as the curing accelerator,
At least one of fine spherical particles (so-called microcapsules) and amine adduct particles is used. Here, the fine spherical particles in the present invention are those having a compound having an imidazole skeleton as a nucleus, and are further obtained by coating the periphery of the nucleus with a coating of a thermosetting resin. Specifically, such fine spherical particles can be produced by a general method such as emulsion polymerization, and a phenol resin, a melamine resin, or an epoxy resin can be suitably used as the coating. The size (particle size) of the fine spherical particles is preferably 50 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. As described above, the smaller the size of the fine spherical particles, the more easily the epoxy resin composition penetrates into the gap between the semiconductor chip and the circuit board when performing flip-chip mounting. The cured product is uniformly dispersed in the composition, and the entire cured product obtained can be made homogeneous. As the above-mentioned imidazole-based microcapsule-type curing accelerator, those which are commercially available from Asahi Kasei Corporation under the trade name "NOVACURE" can be used.

On the other hand, the amine adduct particles are those synthesized from amines, imidazoles, amino acids, amides, and various epoxy resins, and the size (particle size) of the amine adduct particles is the same as that of the fine spherical particles described above. alike,
It is preferably at most 50 μm, more preferably at most 10 μm, particularly preferably at most 5 μm. The smaller the size, the better the penetration of the epoxy resin composition and the more uniform the cured product as a whole. As the curing accelerator for the amine adduct particles, those commercially available from Ajinomoto Co. under the trade name "AMICURE" can be used.

When the fine spherical particles and the amine adduct particles are contained in the epoxy resin composition, the epoxy resin composition can be stored for a long period of time, and the characteristics suitable for flip chip mounting can be obtained. That is, it can exhibit permeability and fillet properties. Although the reason for this is not clear at present, it is thought that trace amines eluted from these curing accelerators into the liquid epoxy resin composition interact with other components to exert an influence. Inferred.

In the present invention, as the inorganic filler,
Spherical amorphous silica having a maximum particle size of 0.5 to 20 μm,
Alternatively, at least one of alumina having a maximum particle size of 0.5 to 10 μm is used. Here, the maximum particle size is
The inorganic filler is sieved and is defined as the size of the sieve mesh when 99% by mass or more and less than 100% by mass pass through the sieve. Significantly reduced,
Further, if the particle size is 10 μm or less, it becomes difficult to obtain a sieve. Therefore, in fact, from the cumulative distribution under the sieve measured by a particle size distribution analyzer (distribution indicating what percentage of particles are present below the particle diameter). , 99% point (99% or less of particles are present below this particle diameter). As the above-mentioned spherical amorphous silica, a spherical substance of silicon dioxide having a true specific gravity of 2.2 and having no crystal structure can be used, but if the maximum particle size is less than 0.5 μm, the filler may be used as a filler. It is too fine and the viscosity of the epoxy resin composition increases, and the penetrability into the gap between the semiconductor chip and the circuit board decreases. Conversely, if the maximum particle size exceeds 20 μm, particle clogging may occur when the epoxy resin composition penetrates into the gap, or the resin may have a low viscosity due to heating during curing, and filler particles having a large specific gravity may be formed. Inconveniences such as sedimentation and unevenness of the filler content in the vertical direction occur.

On the other hand, when the maximum particle size of alumina is less than 0.5 μm, the filler is too fine and the viscosity of the epoxy resin composition increases. The penetration into the gap is reduced. Conversely, if the maximum particle size exceeds 10 μm, the resin will have a low viscosity due to heating during curing, and filler particles having a large specific gravity will settle, causing inconsistencies such as uneven filler content in the vertical direction. What happens.
The alumina particles preferably have a spherical shape or a regular polyhedral shape closer to a spherical shape than a plate-like or crushed shape.

The content of the inorganic filler is 10 to 60% by volume in terms of true specific gravity based on the total amount of the epoxy resin composition. Here, the volume% in terms of the true specific gravity is obtained by the following formula: the blending mass of the filler ÷ the true volume (Vf) of the filler obtained by the true specific gravity of the filler and the blending mass of the resin component other than the filler ÷ the true specific gravity True volume other than filler used (Vr)
From this, it is a value obtained by the equation of Vf ÷ (Vf + Vr) × 100. If the content of the inorganic filler calculated in this way in terms of true specific gravity is less than 10% by volume with respect to the total amount of the epoxy resin composition, the epoxy resin in the gap between the semiconductor chip and the circuit board may be used. Although the infiltration property of the composition is excellent, the thermal cyclability is lowered by increasing the thermal expansion coefficient of the cured product, and the moisture resistance is deteriorated by increasing the moisture absorption rate. Conversely, if the content exceeds 60% by volume, the viscosity of the epoxy resin composition increases, and the penetration of the epoxy resin composition into the gap between the semiconductor chip and the circuit board becomes extremely poor. .

As described above, spherical amorphous silica and alumina can be used as a mixture. However, when fillers having different specific gravities are used together, the average specific gravity is determined in advance. And, based on this,
It is possible to determine the true specific gravity converted volume%. Specifically, the average specific gravity of a material composed of n kinds of fillers is defined as {Wi / Σ (Wi / di) (i = i / n), where Wi is the compounding mass of each filler and di is the true specific gravity (i = 1 to n). 1 to n).

The specific surface area of the above-mentioned spherical amorphous silica or alumina is preferably 0.2 to 30 m ² / g. If the specific surface area exceeds 30 m ² / g, thixotropic properties will appear strongly in the epoxy resin composition, and the fluidity may be significantly reduced. Although the lower limit of the specific surface area is set to 0.2 m ² / g, it can be theoretically obtained by performing geometric calculation. That is, in the case of spherical amorphous silica, a sphere having a specific gravity of 2.2 and a diameter of 20 μm is obtained as 0.14 m ² / g, while in the case of alumina, a sphere having a specific gravity of 3.96 and a diameter of 10 μm is obtained. Then, 0.
It is determined to be 15 m ² / g. However, in practice, if the specific surface area falls below 0.2 m ² / g and approaches the above-mentioned geometrically calculated value, a step of thoroughly removing fine powder by a classification operation such as sieving is required, resulting in a significant increase in cost. And become impractical.

When the epoxy resin composition is used for a semiconductor device which may be adversely affected by α rays, uranium (U) or thorium (Th) may be used as the above-mentioned spherical amorphous silica or alumina. It is preferable to use one having a low content of radioisotope such as. U and T of spherical amorphous silica and alumina in such a case
The content of h is preferably 0.5 ppb or less, more preferably 0.1 ppb or less.

In the present invention, it is preferable to use a silane coupling agent or a titanate coupling agent as the coupling agent. If these are contained in the epoxy resin composition, the adhesiveness at the interface between the cured product and the semiconductor chip or circuit board is improved, and the moisture resistance reliability of the semiconductor device can be improved.

Here, as the silane coupling agent,
γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4
Epoxysilanes such as -epoxycyclohexyl) ethyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane Aminosilanes such as γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) ) Vinyl silanes such as silane, vinyl trimethoxy silane, vinyl triethoxy silane, γ-methacryloxy propyl trimethoxy silane, and epoxy type, amino type and vinyl type polymer type silanes, etc. It can be, in particular, epoxy silane, amino silane, and mercapto silane are preferable.

On the other hand, titanate coupling agents include isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, diisopropyl bis (dioctyl phosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraisopropyl Octylbis (ditridecylphosphite) titanate, tetra (2,2-
Diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctylpyrophosphate) oxyacetate titanate, bis (dioctylpyrophosphate) ethylene titanate and the like can be used.

These coupling agents may be used alone or in combination of two or more. Further, the above-mentioned coupling agent may be used by treating the inorganic filler by a wet method or a dry method in advance, or may be used by performing an integral blending method in which it is mixed with a resin.

In the present invention, the compound represented by the above formula (B) or the compound represented by the formula (C) is added as an additive to the epoxy resin composition in an amount of from 0.01 to 0.01%.
It is preferable to contain 1% by mass. A more preferred content is 0.05 to 0.5% by mass. The compound represented by the formula (B) is an alkyl polyetheramine, such as hydroxyethyl laurylamine, polyethylene glycol laurylamine, or polyethylene glycol stearylamine. A compound having 1 to 10 ethylene glycol groups in one molecule. Can be used. On the other hand, equation (C)
Are polyethylene glycol alkyl phenol ethers, such as polyethylene glycol nonyl phenol ether and polyethylene glycol octyl phenol ether, and those having a polyethylene glycol chain length of 2 to 15 can be used. These compounds may be used alone or
More than one type may be used in combination.

The compounds represented by the above formulas (B) and (C), even when contained in the epoxy resin composition, are unlikely to significantly affect the viscosity characteristics. This has the effect of increasing the penetration into the gap between the semiconductor chip and the circuit board in chip mounting and enhancing the fillet property. However, if the content of these compounds is less than 0.01% by mass, there is a possibility that the effect of sufficiently increasing the infiltration property and fillet property may not be obtained. Although the properties and fillet properties are not deteriorated, there is a possibility that inconveniences such as a decrease in moisture resistance reliability and a decrease in the shelf life of the epoxy resin composition may occur.

Further, other substances can be added to the epoxy resin composition, if necessary, as long as the object of the present invention is not impaired. Examples of such a substance include a flame retardant, a low elasticity agent, a coloring agent, a diluent, and an antifoaming agent.

In preparing a uniform liquid epoxy resin composition, the above-mentioned components are generally mixed with a stirring-type disperser, dispersed and mixed with a bead mill, or dispersed and mixed with a three-roll mill. Or the like, but is not limited to these methods.

The liquid epoxy resin composition prepared as described above can be used as a sealing material in flip chip mounting. As a semiconductor device having a flip-chip structure for sealing, a semiconductor device in which electrodes of a semiconductor chip and electrodes of a circuit board are electrically joined by metal bumps can be used. In such a semiconductor device, the metal bump is formed of a metal such as solder, gold, or copper, and a gap is formed between the semiconductor chip and the circuit board via the metal bump. Here, as the circuit board, an organic substrate including a fiber base material such as FR4 or FR5, or a build-up type organic substrate including no fiber base material,
Further, an organic film such as polyimide or polyester, or an inorganic substrate such as alumina or glass can be used.

In infiltrating the liquid epoxy resin composition into the gap, it is important to take a procedure that does not involve air.
In general, the epoxy resin composition is applied to one or two sides of a semiconductor chip with a dispenser or the like, and heated to a temperature lower than a curing temperature as needed.
This allows the epoxy resin composition to penetrate and fill the gap due to the capillary action, and form a fillet from the end of the semiconductor chip to the circuit board.
Thereafter, in the present invention, the curing of the epoxy resin
This is performed at a temperature of up to 180 ° C. At a low temperature of less than 110 ° C., the curing is difficult to proceed, so that the heat resistance of the epoxy resin composition is lowered, and the temperature cycle property after curing and the moisture resistance reliability may be reduced. Conversely, at a high temperature exceeding 180 ° C., air bubbles (voids) may be generated inside the cured product, and this may also reduce the temperature cycleability after curing and the moisture resistance reliability.

As a semiconductor device having a flip-chip structure for infiltrating the epoxy resin composition, a metal bump of a semiconductor chip is formed of gold,
What bonded this metal bump and the electrode of the circuit board via conductive paste can be used conveniently. Such a bonding method is particularly called a stud bump bonding (SBB). In this case, the metal bump is not formed by plating, but is formed as a two-step projection (stud bump) by ball bonding. It is.

As described above, since gold is used instead of solder for the metal bumps, the metal bumps can be formed by utilizing the ball bonding forming function of the wire bonding apparatus. In addition, a metal bump having a narrow pitch can be formed, and since the metal bump is formed as a two-step projection as described above, the spread of the conductive paste can be suppressed when the semiconductor chip is connected to the circuit board. You can do it. Further, when solder is used as the metal bump, a flux removing operation is required. However, since the SBB uses gold as the metal bump, the flux removing process becomes unnecessary.

On the other hand, the conductive paste in the present invention is not particularly limited. For example, a conventionally known silver paste comprising silver powder as a metal powder, phenoxy resin as a thermosetting resin, and an organic solvent may be used. The conductive paste is used after being applied and dried in advance on the electrode surface of the circuit board when joining the semiconductor chip and the circuit board.

As described above, in the SBB, the metal bump and the electrode of the circuit board are joined via the conductive paste, and a gap is provided between the semiconductor chip and the circuit board by the metal bump and the conductive paste. Are formed. Conventionally, a low-viscosity epoxy resin composition containing, as a main component, an epoxy resin such as a bisphenol A type epoxy resin or a bisphenol F type epoxy resin and an acid anhydride such as MHHPA or MTHPA as a liquid sealing material. However, when such a material is used, the metal bump and the circuit board are not electrically connected after curing, or the electrical resistance of the connection portion is considerably large. Phenomenon, which may make it impossible to endure actual use. Therefore, when the epoxy resin composition prepared in the present invention is used instead of the conventional sealing material, the electrical connection between the semiconductor chip and the circuit board after curing can be completely maintained. Although the reason for this is not clear at present, the liquid resin component containing the formula (A) swells and softens the dried conductive paste, thereby promoting the percolation (contact of the particles) of the conductive particles by the subsequent curing shrinkage. It is presumed that they do so.

[0059]

The present invention will be specifically described below with reference to examples.

Examples 1 to 19 and Comparative Examples 1 to 5 For Examples 1 to 19, the amounts (parts by mass) shown in Tables 1 and 2 below were used. For Comparative Examples 1 to 5, Each component was mixed using a disper (manufactured by Tokushu Kika Kogyo Co., Ltd.) in the amount (parts by mass) shown in Table 3 below to prepare an epoxy resin composition.

The raw materials used in Tables 1 to 3 are as follows.

(Epoxy resin) Resin A: bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., product number "Epicoat 828", epoxy equivalent 190) Resin B: bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd., product number "YD-8125", epoxy equivalent 17
2) Resin C: bisphenol F type epoxy resin (manufactured by Toto Kasei Co., Ltd., product number “YD-8170”, epoxy equivalent 16
0) Resin D: Naphthalene type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., product number “HP-4032D”, epoxy equivalent 143) (Curing agent) Curing agent A: Triene having 10 carbon atoms (formula (E)) Alicyclic acid anhydride (acid anhydride represented by formula (A-2), manufactured by Yuka Shell Epoxy Co., Ltd., product number “YH-306”) synthesized from maleic anhydride and the shown cymene β-form ,
Acid anhydride equivalent 234) Curing agent B: methyl hexahydrophthalic anhydride (MHHP)
A, manufactured by Dainippon Ink and Chemicals, Inc., part number "B-65"
0, acid anhydride equivalent 168) (Curing accelerator) Curing accelerator A: Microcapsules having imidazoles as nuclei (manufactured by Asahi Chemical Industry Co., Ltd., product number “NOVACURE HX3”)
722 ") Curing accelerator B: amine adduct (manufactured by Ajinomoto Co., Inc., product number" Amicure PN23 ") (coupling agent) Coupling agent A: γ-glycidoxypropyltrimethoxysilane (manufactured by Nippon Unicar Co., Ltd., product number" A-18
7)) Coupling agent B: tetraisopropylbis (dioctylphosphite) titanate (manufactured by Ajinomoto Co., Inc., product number "KR-41B") (additive) Additive A: polyethylene glycol laurylamine (shown by the formula (B)) Compound, n = 12, x + y = 2, manufactured by NOF Corporation, product number “Nymeen L-202”) Additive B: Polyethylene glycol stearylamine (compound represented by formula (B), n = 18, x + y = 9,
Additive C: Polyethylene glycol nonylphenol ether (compound represented by formula (C), n = 9, m = 4 or 5, manufactured by NOF Corporation, product number “Nimeen S-210” manufactured by NOF Corporation) Nonion NS-20
4.5 ”) Additive D: polyethylene glycol octylphenol ether (compound represented by formula (C), n = 8, m =
6. Product number "Nonion NH-20" manufactured by NOF Corporation
6 ") (Inorganic filler) Silica A: spherical amorphous silica (manufactured by Mitsubishi Rayon Co., Ltd., product number" QS-4 ", maximum particle size 14 μm, average particle size 5)
μm) Silica B: spherical amorphous silica (manufactured by Admatechs Co., Ltd., product number “SO-E2”, maximum particle size 3 μm, average particle size 0.6 μm) Silica C: spherical amorphous silica (manufactured by Tokuyama Corporation, Product number “SE-8T”, maximum particle size 45μm, average particle size 9μ
m) Silica D: spherical amorphous silica (manufactured by Nippon Aerosil Co., Ltd., product number “OX-50”, maximum particle size 0.1 μm, average particle size 0.05 μm) Alumina A: rounded granular α-alumina ( Manufactured by Sumitomo Chemical Co., Ltd., product number “AA-2”, maximum particle size 7 μm,
Average particle size 2.2 μm, true specific gravity 3.96) Alumina B: spherical α-alumina (manufactured by Admatechs Co., Ltd., product number “AO-502”), maximum particle size 5 μm, average particle size 0.4 μm, true specific gravity 3.6 )

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[Table 1]

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[Table 2]

[0065]

[Table 3]

In Tables 1 to 3, the equivalent ratio (10
0 :) indicates an oxide equivalent relative to an epoxy equivalent of 100, filler volume% indicates a volume percentage of the inorganic filler calculated as true specific gravity, and filler mass% indicates an inorganic filler in the epoxy resin composition. % By mass.

In calculating the volume percentage of the inorganic filler converted to the true specific gravity, the true specific gravity of the resin component other than the filler is set to 1.2, and the true specific gravities of the silicas A to D are each set to 2.2. Alumina A and alumina B are in a mass ratio of 8: 2.
(In the case of Example 2) were calculated based on their true specific gravities, and the average specific gravities were set to 3.88.

Then, Examples 1 to 19 and Comparative Examples 1 to 5
The characteristics of the epoxy resin composition obtained in the above were measured by the following methods.

(1) Viscosity of Epoxy Resin Composition Using a rotor rotation type viscometer (Brookfield, model “HBT”, rotor symbol “SC”), the viscosity was 25%.
The viscosity at ° C was measured.

(2) Penetration into Flip Chip (FC) The semiconductor device used for the test was an electrode on an FR5-grade circuit board, a chip size of 0.4 mm thick, and a 10 mm square complementary metal-oxide semiconductor (CMOS).
r) The electrode around the chip of the gate array element is 70
They are connected by solder bumps having a height of μm.
An epoxy resin composition is applied to one end of the semiconductor chip with a dispenser, the circuit board is immediately placed on a hot plate at 60 ° C., and then the side opposite to the side on which the epoxy resin composition is applied is placed. The time to reach was measured. Those with 30 seconds or less are marked with “◎”, those with more than 30 seconds and less than 60 seconds with “○”, those with more than 60 seconds with 2 minutes or less as “△”, and those with more than 2 minutes with “×” Judged.

(3) Fillet Property With respect to the semiconductor device for which the penetration property of (2) was evaluated, it was observed how much the fillet was formed between the end of the semiconductor chip and the circuit board. If the same fillet is formed on all four sides of the semiconductor chip, "◎" is applied. If the fillet is formed on all four sides of the semiconductor chip, the degree is different, "○", the epoxy resin composition is applied. If no fillet is formed on the side opposite to the side where the fillet is formed, and if fillets are formed on multiple other sides, "△", fillets are formed on sides other than the side where the epoxy resin composition was applied. If not, it was judged as "x".

(4) Temperature Cycle (TC) Properties The epoxy resin composition applied to the semiconductor device evaluated for infiltration in (2) was cured by heat treatment under the following two conditions. Condition 1 is at 150 ° C. for 2 hours, and Condition 2 is at 150 ° C. for 30 minutes. Then, ten semiconductor devices which had good electrical operation confirmation results after curing were taken out for each condition and used as test samples. Next, these test samples were subjected to −55 ° C.
Temperature cycle test for 30 minutes at room temperature, 5 minutes at room temperature, 30 minutes at 150 ° C., and 5 minutes at room temperature. The operation of the semiconductor device is checked every 100 cycles up to 2000 cycles. Judged. For each condition, the number of cycles in which the number of defects in 10 test samples became more than half for the first time was determined.

(5) Humidity-Reliable Reliability (PCT) As in the case of (4), the semiconductor device after curing under the conditions 1 and 2 was checked for good electrical operation. And a test sample. Then, for these test samples, 121 ° C. at 2 atm.
Pressure cooker test (PCT) of 100
Check the operation of the semiconductor device every 50 hours until 0 hour,
Pass / fail was determined. For each condition, the total processing time when the number of defects in 10 test samples reached half or more was determined.

(6) SBB Initial Connectivity The configuration of the SBB type semiconductor device used in the test is 10
A gold bump having a height of 40 μm formed on an electrode in the periphery of a chip of a CMOS gate array device of mm square is connected to an electrode on an FR5 grade circuit board via a silver paste. An epoxy resin composition is introduced into the semiconductor device by the method described in (2),
After performing the curing treatment for 30 minutes, the operation of the semiconductor device was confirmed, and the number of disconnection defects was determined. Whether or not electrical continuity is secured between the gold bumps and the silver paste connecting the electrodes on the semiconductor chip side and the electrodes on the circuit board side is determined by checking whether there is a disconnection failure in this operation check. Can be.

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[Table 4]

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[Table 5]

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[Table 6]

As can be seen from Tables 4 to 6, Examples 1 to 1
9 and Comparative Examples 1 to 5, the viscosity of the epoxy resin composition of each of the Examples was low,
It is confirmed that the penetration property and the fillet property are excellent.
In addition, it is confirmed that the cured product of each of the examples is excellent in the temperature cycle property and the heat resistance reliability, and that the electrical connection reliability in the SBB can be sufficiently secured.

On the other hand, it was confirmed that all of the comparative examples had extremely poor temperature cyclability of the cured product, heat resistance reliability, and connection reliability in SBB, and were not practically used.

[0080]

As described above, the epoxy resin composition according to the first aspect of the present invention is an epoxy resin composition which is liquid at room temperature and comprises an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components. Wherein the epoxy resin contains at least one of a bisphenol A epoxy resin, a bisphenol F epoxy resin, and a naphthalene epoxy resin, and the curing agent contains an acid anhydride represented by the above formula (A). As a curing accelerator, containing a compound having an imidazole skeleton as a nucleus and containing at least one of fine spherical particles obtained by coating the periphery of the nucleus with a coating of a thermosetting resin, or amine adduct particles, As a filler, spherical amorphous silica having a maximum particle size of 0.5 to 20 μm, or a maximum particle size of 0.5 to 10 μm
Since at least one of alumina, which is m, is contained at 10 to 60% by volume in terms of true specific gravity with respect to the total amount of the epoxy resin composition, the epoxy resin composition penetrates into a narrow gap between a semiconductor chip and a circuit board. The semiconductor chip is filled without containing bubbles, and a fillet can be formed from the end to the circuit board at the end of the semiconductor chip. Moreover, the epoxy resin composition filled in the gaps in this way can be cured in a short time. Further, the cured product disperses the stress applied to the vicinity of the metal bump, thereby preventing the metal bump from being broken or the like, thereby improving the temperature cycle property and the moisture resistance reliability. .

According to a second aspect of the present invention, in the first aspect, a bisphenol A type epoxy resin having an epoxy equivalent of 180 or less is used as the epoxy resin, so that the viscosity, curability, and heat resistance of the epoxy resin composition are improved. It can maintain a good balance of properties, hygroscopicity, etc., in particular, it can lower the viscosity and express high fluidity and can sufficiently secure the heat resistance of the cured product. is there.

According to a third aspect of the present invention, in the first or second aspect, the ratio of the epoxy equivalent of the epoxy resin to the curing agent equivalent of the curing agent is 100: 60 to 100: 120. The strength of the cured product such as heat resistance and adhesive strength can be sufficiently ensured, and the moisture absorption rate of the cured product can be suppressed to improve the moisture resistance reliability.

Further, the invention of claim 4 uses the silane coupling agent or titanate coupling agent as the coupling agent in any one of claims 1 to 3, so that the cured product of the epoxy resin composition and the semiconductor chip In addition, the adhesiveness of the interface with the circuit board is improved, and the humidity resistance of the semiconductor device can be improved.

The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the compound represented by the above formula (B) or the compound represented by the above formula (C) is used as an additive.
Since it is contained in an amount of 0.01 to 1% by mass with respect to the total amount of the epoxy resin composition, the penetration of the epoxy resin composition into the gap between the semiconductor chip and the circuit board in flip chip mounting or the fillet property is enhanced. Or something you can do.

According to a sixth aspect of the present invention, in a semiconductor device manufactured by bonding a metal bump formed on a semiconductor chip to a circuit board, the semiconductor chip is flip-chip mounted on the circuit board. A gap formed between the semiconductor chip and the circuit board via the metal bump is filled with the epoxy resin composition according to any one of claims 1 to 5, and a fillet portion is formed from an end of the semiconductor chip to the circuit board. Is formed and the epoxy resin composition is heated and cured at 110 to 180 ° C., so that it is possible to realize excellent temperature cyclability and moisture resistance reliability as a semiconductor device.

According to a seventh aspect of the present invention, in the sixth aspect, a conductive paste comprising a metal powder, a thermoplastic resin, and an organic solvent is applied and dried on the surface of the circuit board.
By bonding metal bumps made of gold to the circuit board via this conductive paste, the semiconductor chip is mounted and manufactured on the circuit board, realizing excellent temperature cycling and moisture resistance reliability as a semiconductor device. And the electrical connection reliability between the semiconductor chip and the circuit board can be ensured.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/56 H01L 21/56 E 23/29 23/30 R 23/31 (72) Inventor Shinji Hashimoto Osaka Matsushita Electric Works Co., Ltd., 1048, Kadoma, Kadoma, Fumonma-shi (72) Inventor Hirohisa Hino 1048 Kadoma, Kadoma, Kadoma, Osaka, Japan F term in Denko Corporation (reference) 4J002 CD041 CD051 CH022 DE148 DJ018 ED069 EL136 EN099 EU117 EX039 EZ009 FA087 FA088 FB267 FD018 FD146 FD157 GQ05 4J036 AC01 AC05 AD08 BA02 DB21 DC18 DC40 FA03 FA05 FA10 FA12 FA07 GA10 JA10 CA05 DB17 EA02 EB02 EB04 EB06 EB07 EB08 EB12 EB13 EB18 EB19 EC01 EC05 EC07 EC20 GA10 5F061 AA01 BA03 CA05 FA06

Claims (7)

[Claims] 1. A room temperature liquid epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components, wherein at least a bisphenol A epoxy resin and a bisphenol F epoxy resin are used as epoxy resins. Or a naphthalene type epoxy resin, as a curing agent, an acid anhydride represented by the following formula (A), and as a curing accelerator, a compound having an imidazole skeleton as a nucleus. Containing at least one of fine spherical particles or amine adduct particles obtained by coating the periphery with a coating of a thermosetting resin, and as an inorganic filler, a spherical amorphous having a maximum particle size of 0.5 to 20 μm. At least one of porous silica and alumina having a maximum particle size of 0.5 to 10 μm is calculated as true specific gravity based on the total amount of the epoxy resin composition. Epoxy resin composition characterized by containing 60% by volume. Embedded image 2. An epoxy resin having an epoxy equivalent of 1
The epoxy resin composition according to claim 1, wherein a bisphenol A type epoxy resin having a weight of 80 or less is used. 3. The epoxy resin composition according to claim 1, wherein the ratio between the epoxy equivalent of the epoxy resin and the curing agent equivalent of the curing agent is from 100: 60 to 100: 120. 4. The epoxy resin composition according to claim 1, wherein a silane coupling agent or a titanate coupling agent is used as the coupling agent. 5. An epoxy resin composition containing 0.01 to 1% by mass of a compound represented by the following formula (B) or a compound represented by the following formula (C) as an additive. The epoxy resin composition according to any one of claims 1 to 4, wherein: Embedded image 6. In a semiconductor device manufactured by bonding a metal bump formed on a semiconductor chip to a circuit board and flip-chip mounting the semiconductor chip on the circuit board, the semiconductor chip and the circuit board are connected via the metal bump. Filling the gap formed between the epoxy resin composition according to any one of claims 1 to 5, and forming a fillet portion from an end of the semiconductor chip to the circuit board,
A semiconductor device obtained by heating and curing the epoxy resin composition at 110 to 180 ° C. 7. A conductive paste made of a metal powder, a thermoplastic resin, and an organic solvent is applied to a surface of a circuit board and dried, and a metal bump formed of gold is joined to the circuit board via the conductive paste. 7. The semiconductor device according to claim 6, wherein the semiconductor chip is mounted and manufactured on a circuit board.