JP3446730B2 - Epoxy resin composition and semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flip-chip mounting which is carried out by electrically connecting a semiconductor chip and a circuit board with metal bumps in order to minimize the mounting area of the semiconductor chip on the circuit board. 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 mounting a semiconductor chip packaged with resin or the like on a circuit board, soldering has been widely used. After that, in order to reduce the size of electronic devices, semiconductor chips are used. Bare chip mounting was devised in which the chip was mounted directly on the circuit board without being housed in the package. In the early stage of 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 adhered 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, and then the semiconductor chip and the metal. The wire and the resin are sealed.

After that, a method called flip-chip mounting appeared in order to further miniaturize the mounting area of the semiconductor chip on the circuit board. In this method, the circuit of the semiconductor chip and the electrode of the circuit board are electrically connected using metal bumps. Specifically, for example, a vapor deposition film of a contact metal or a diffusion preventing metal is formed in advance on a terminal electrode of a circuit of a semiconductor chip, and a solder protruding electrode is further formed thereon by plating. The bump electrodes thus formed are metal bumps. Then, the metal bumps are made to face the electrodes of the circuit board so that the semiconductor chip is faced down and heated to a high temperature to fuse the solder forming the metal bumps to the electrodes of the circuit board and mount the semiconductor chip on the circuit board. Is to do. Such a mounting method is considered to be an effective method because it has high mechanical strength after connection by metal bumps and can be connected all at once (for example, Industrial Research Committee, issued January 15, 1980). , Japan Microelectronics Association, "IC Packaging Technology").

C4 (Controlled Collapse Chip Con
Regarding flip chip mounting called nection),
As shown in U.S. Pat. No. 5,121,190 and Japanese Unexamined Patent Publication No. 6-61303, the reliability of a solder-bonding object that connects a semiconductor chip and a circuit board (in the above-mentioned publication, referred to as a chip carrier or the like) is secured In order to achieve this, a solder interconnection structure having a gap between the semiconductor chip and the circuit board filled with an encapsulant (in the above publication, described as an encapsulant, etc.) and a manufacturing method thereof have been proposed. .

In addition, stud bump bonding (SB
Regarding the mounting method called B), JP-A-11-35
As shown in Japanese Patent No. 4575, when mounting a semiconductor chip (in the above-mentioned publication, a semiconductor element) on a circuit board, a protruding electrode formed of gold of the semiconductor chip is attached to a conductive adhesive containing silver powder. After being connected to the connection electrode of the circuit board via an agent, a liquid sealing material (described as a sealing resin in the above publication) is allowed to penetrate into the gap between the semiconductor chip and the circuit board, and then the sealing material is sealed. A semiconductor device (described as a semiconductor unit in the above publication) and a semiconductor chip mounting method in which a stopper is cured have also been proposed.

In these prior arts, the main reason why a liquid encapsulant is required is that the temperature cycle property of a semiconductor device in which a semiconductor chip is mounted on a circuit board is improved. Usually, the semiconductor chip and the circuit board have different coefficients of thermal expansion. Therefore, under actual use conditions, a thermal cycle is applied to the vicinity of the metal bumps, which causes repeated shear stress in the same vicinity, causing fatigue phenomenon. is there. Therefore, in the unsealed semiconductor device in which the sealing material is not used, the stress thus generated cannot be dispersed, and the metal bumps are easily cracked and destroyed. On the other hand, in a semiconductor device that is sealed by using a sealing material, this sealing material has a function of dispersing stress.
The destruction of the metal bumps is prevented.

[0007]

However, as the objects and applications of flip-chip mounting expand, the encapsulant, in addition to the above-mentioned temperature cycle property, also has penetrability, fillet property, quick curing property, moisture resistance reliability and the like. It has become necessary to have excellent performance.

Here, the penetrability is evaluated by the time taken for the encapsulating material to enter the gap between the semiconductor chip and the circuit board, and it can be said that the shorter the time, the better the penetrability.
Further, the excellent fillet property means that the fillet is naturally formed from the side surface of the semiconductor chip to the circuit board. The excellent rapid curing property means that the encapsulating material is hardened in a short time and necessary. It means that reliability can be realized.

Further, the above-mentioned Japanese Patent Laid-Open No. 11-354575.
In the SBB in the publication, a special encapsulant is required, and the encapsulant may not be able to secure the electrical connection reliability unless it takes a long time of about 4 hours for curing. is there. Therefore, there is a demand for an encapsulant that can be cured in a short time in SBB and that can secure electrical connection reliability after curing.

As described above, the performance such as the temperature cycle property, the penetration property, the fillet property, the quick curing property, the moisture resistance reliability, and the reliability of the electrical connection after curing are all low in cost and high in flip chip mounting. It is necessary for application.

The present invention has been made in view of the above points, and is excellent in temperature cycle property, penetration property, fillet property, fast curing property, and moisture resistance reliability in expanding the applicable fields of flip chip mounting. An object of the present invention is to provide an epoxy resin composition for encapsulation that can secure electrical connection reliability, and a semiconductor device manufactured using this epoxy resin composition.

[0012]

The epoxy resin composition according to claim 1 of the present invention is an epoxy resin composition which is liquid at room temperature and contains an epoxy resin, a curing agent, a curing accelerator and an inorganic filler as essential components. In, at least one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a naphthalene type epoxy resin is contained as an epoxy resin, and an acid anhydride represented by the following formula (A) is contained as a curing agent. , As a curing accelerator, fine sphere particles obtained by coating a compound having an imidazole skeleton with a core and a coating of a thermosetting resin around the core, or containing at least one of amine adduct particles, and inorganic 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
It is characterized in that at least one of the alumina of m is contained in an amount of 10 to 60% by volume in terms of true specific gravity with respect to the total amount of the epoxy resin composition.

[0013]

[Chemical 3]

A second aspect of the 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.

The invention of claim 3 is characterized in that, in claim 1 or 2, 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. 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.

A fifth aspect of the present invention is, in any one of the first to fourth aspects, a compound represented by the following formula (B) or a compound represented by the following formula (C) is added as an additive.
It is characterized by containing 0.01 to 1 mass% with respect to the total amount of the epoxy resin composition.

[0018]

[Chemical 4]

A semiconductor device according to a sixth aspect of the present invention is a semiconductor device manufactured by flip-chip mounting a semiconductor chip on a circuit board by bonding metal bumps formed on the semiconductor chip to the circuit board. The 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 the fillet portion extends from the end of the semiconductor chip to the circuit board. Is formed, and the epoxy resin composition is heated to 110 to 180 ° C. and cured.

According to a seventh aspect of the invention, in the sixth aspect, the conductive paste composed of the metal powder, the thermoplastic resin, and the organic solvent is applied to the surface of the circuit board and dried, and
The semiconductor chip is mounted on the circuit board and manufactured by joining metal bumps made of gold to the circuit board via the conductive paste.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION 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, details of each of the above components will be described in order.

In the present invention, the epoxy resin includes bisphenol A type epoxy resin obtained by the reaction of bisphenol A and epichlorohydrin, bisphenol F type epoxy resin obtained by the reaction of bisphenol F and epichlorohydrin, 1,6-dihydroxynaphthalene. At least one kind of naphthalene type epoxy resin obtained by the reaction with epichlorohydrin is used. However, if the epoxy resin as described above is used, as an epoxy resin other than these,
It is also possible to use a novolac 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 the molecule, and the like.

As the epoxy resin, it is 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, a good balance of the viscosity, curability, heat resistance of the cured product, hygroscopicity, etc. of the epoxy resin composition can be maintained. is there. The epoxy equivalent is 180 or less,
When the content is within this range, the content of the linear and high molecular weight epoxy resin becomes remarkably low, the viscosity of the epoxy resin composition can be lowered, and high fluidity can be expressed. This is because the heat resistance of the cured product does not decrease.

The pure bisphenol A type epoxy resin is bisphenol A diglycidyl ether, and its molecular weight is 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 can only be the case above, the practical lower limit is 170.

In the present invention, the acid anhydride represented by the above formula (A) is used as the curing agent. 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 having three carbon-carbon double bonds in one molecule among the monoterpenes represented by the molecular formula C ₁₀ H ₁₆ , and a compound in which two double bonds are conjugated (hereinafter referred to as triene). Of monoterpene) and maleic anhydride are synthesized by 6-membered cyclization by Diels-Alder reaction. Therefore, R1 to R3 bonded to the 6-membered ring can be considered to be derived from the triene monoterpene. The triene monoterpene is a monoterpene that does not have a cyclic structure among monoterpenes.

For example, as a triene monoterpene,
Mention may be made of myrcene represented by the following formula (D). This myrcene reacts with maleic anhydride as represented by the following chemical reaction formula (I) to give formula (A-1) (formula (A An acid anhydride represented by the specific example 1) is produced. Here, among the carbon atoms forming the 6-membered ring of this acid anhydride, four carbon atoms are numbered 3 to 6 as shown in the formula for convenience, respectively, and hereinafter, for example, carbon numbered 3. The atom is expressed as the carbon atom at the 3rd position, and each carbon atom is specified. As shown in formula (A-1), R1
Is a hydrocarbon group and is bonded to the carbon atom at the 4-position, and this R1 contains 6 carbon atoms and 11 hydrogen atoms. At this time, R2 and R3 are both limited to hydrogen atoms, but R2 and R3 are not limited to the 3-position, 5-position, or 6-position.
It can be thought of as any hydrogen atom bonded to a carbon atom at position. Therefore, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0028]

[Chemical 5]

Another example of the triene monoterpene other than the above is β-form of ocimene represented by the following formula (E). The β-form of ocimene is represented by the following chemical reaction formula (II). As shown by the formula (1), it 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 and are bonded to carbon atoms at the 3- and 4-positions, respectively, and R1 and R2 are
The number of carbon atoms contained in 2 and 6 is 6 in total, and the number of hydrogen atoms is 12 in total. At this time, R3 is limited to a hydrogen atom, but this R3 can be considered to be any hydrogen atom bonded to the carbon atom at the 3-position, 5-position, or 6-position. Therefore, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0030]

[Chemical 6]

Further, as another monoterpene of triene other than the above, there can be mentioned one represented by the following formula (F), which is represented by the following chemical reaction formula (III):
As shown by the formula (A-
3) An acid anhydride represented by (another specific example of the formula (A)) is produced. As shown in this formula (A-3), R
1 to R3 are all hydrocarbon groups, and are respectively in the 3-position,
It is bonded to the carbon atoms at the 4th and 6th positions, the total number of carbon atoms of R1 to R3 is 6, and the total number of hydrogen atoms is 13.

[0032]

[Chemical 7]

The above-mentioned three examples show cases where one, two, and three hydrocarbon groups are used as R1 to R3. The terpene derived from a natural product is a triene (carbon-carbon double bond is 1 Even if it has three in the molecule), there are many structural isomers, and 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 only those produced from the above-mentioned triene monoterpenes as specific examples.

When the acid anhydride represented by the above formula (A) is contained in the epoxy resin composition as a curing agent, temperature cycle property in flip chip mounting,
The fillet property, the moisture resistance reliability, and the connection reliability can be appropriately expressed. The reason for this is not clear so far, but it is presumed that the structure of the monoterpene interacts with and influences the other components in the epoxy resin composition. Therefore, the above-mentioned properties cannot be realized only by the conventional typical liquid acid anhydrides such as methylhexahydrophthalic anhydride (MHHPA) and methyltetrahydrophthalic anhydride (MTHPA).
In addition, it is necessary that the acid anhydride represented by the formula (A) is contained in the epoxy resin composition, and if this is satisfied, the acid anhydride in one molecule like MHHPA and MTHPA described above is contained. An acid anhydride having one or more non-hydroxyl groups can also be used together as a curing agent.

Here, the molar ratio of the stoichiometric reactive groups of the epoxy resin and the curing agent, that is, the ratio (equivalent ratio) of the epoxy equivalent and the curing agent equivalent is 100: 60 to 100: 120.
Is preferable, and more preferably 100: 75.
˜100: 100. When it is out of 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 even if cured, the heat resistance of the cured product May decrease or the strength of the cured product may decrease.
On the other hand, if the curing agent equivalent exceeds 120, the heat resistance of the cured product may decrease, the adhesive strength after curing may decrease, and the moisture absorption rate of the cured product may increase. Since an acid anhydride is used as a curing agent in the present invention, the curing agent equivalent is also referred to as acid anhydride equivalent.

In the present invention, the curing accelerator is
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 have a compound having an imidazole skeleton as a core, and are obtained by further coating the periphery of this core with a film 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 preferably used as the coating. The size (particle diameter) of the fine spherical particles is preferably 50 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. Thus, the smaller the size of the fine spherical particles, the easier the epoxy resin composition will penetrate into the gap between the semiconductor chip and the circuit board during flip-chip mounting. The composition is uniformly dispersed in the composition, and the resulting cured product can be made homogeneous. As the above-mentioned imidazole-based microcapsule type curing accelerator, those commercially available from Asahi Kasei Co., Ltd. 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 the like and various epoxy resins, and the size (particle size) of the amine adduct particles is also the above fine spherical particles. alike,
The thickness is preferably 50 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. The smaller the size, the better the penetration of the epoxy resin composition and the more uniform the entire cured product. As the curing accelerator for the amine adduct particles, those commercially available from Ajinomoto Co., Inc. under the trade name "Amicure" can be used.

When the fine spherical particles or amine adduct particles described above 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 are obtained. That is, it is possible to express penetrability and fillet property. The reason for this is not clear so far, but it is considered that the trace amount of amines eluted from these curing accelerators into the liquid epoxy resin composition interacts with other components to exert an influence. Inferred.

Further, 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
When the inorganic filler is passed through a sieve and 99% by mass or more and less than 100% by mass passes through the sieve, it is defined as the size of the mesh of the sieve, but when the opening is about 40 μm or less, the efficiency of the sieve is small. Significantly reduced,
If the particle size is less than 10 μm, it will be difficult to obtain the sieve. Therefore, in practice, the cumulative distribution under the sieve measured by a particle size distribution measuring device (the distribution showing how many% of the particles below the particle size exist) , 99% point particle size (99% of all particles are present below this particle size). As the spherical amorphous silica, spherical particles of silicon dioxide having a true specific gravity of 2.2 and not having a crystal structure can be used, but if the maximum particle size is less than 0.5 μm, the filler will be used as a filler. If it is too fine, the viscosity of the epoxy resin composition will increase, and the penetrability into the gap between the semiconductor chip and the circuit board will decrease. On the other hand, when the maximum particle size exceeds 20 μm, particle clogging occurs when the epoxy resin composition penetrates into the above-mentioned gap, and the resin has a low viscosity due to heating during curing, and filler particles having a large specific gravity are generated. It causes sedimentation and causes inconveniences such as non-uniformity of the filler content in the vertical direction.

On the other hand, also with respect to alumina, if the maximum particle size is less than 0.5 μm, the filler is too fine and the viscosity of the epoxy resin composition increases, and the viscosity between the semiconductor chip and the circuit board is increased. Penetration into the gap is reduced. On the other hand, if the maximum particle size exceeds 10 μm, the resin becomes less viscous due to heating during curing, and the filler particles having a large specific gravity settle down, resulting in non-uniformity of the filler content in the vertical direction. It occurs.
In addition, the particle shape of alumina is preferably a spherical shape or a regular polyhedron shape close to a spherical shape rather than a plate shape or a crushed shape.

The content of the above inorganic filler is 10 to 60% by volume in terms of true specific gravity with respect to the total amount of the epoxy resin composition. Here, the volume% in terms of true specific gravity is obtained by multiplying the true volume of the filler by the compounding mass of the filler / the true specific gravity of the filler (Vf) and the compounding mass of the resin component other than the filler / the true specific gravity thereof. True volume (Vr) other than the used filler
Is the value obtained from the equation Vf ÷ (Vf + Vr) × 100. When the content of the inorganic filler in terms of true specific gravity calculated as described above is less than 10% by volume based on the total amount of the epoxy resin composition, the epoxy resin in the gap between the semiconductor chip and the circuit board is Although the composition has excellent penetrability, the cured product has a large thermal expansion coefficient, which lowers the temperature cycle property, and a high moisture absorption ratio, which deteriorates the moisture resistance. On the other hand, when the content exceeds 60% by volume, the viscosity of the epoxy resin composition increases, so that the penetrability of the epoxy resin composition into the gap between the semiconductor chip and the circuit board is significantly deteriorated. .

As described above, spherical amorphous silica and alumina can be mixed and used. However, when fillers having different specific gravities are used in combination as described above, the average specific gravities are obtained in advance. Then, based on this, the above formula gives
The volume percentage in terms of true specific gravity can be determined. Specifically, the average specific gravity of those composed of n kinds of fillers is ΣWi / Σ (Wi / di) (i =, where Wi is the compounding mass of each filler and di (i = 1 to n) is the true specific gravity). 1 to n).

The specific surface area of the 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 be strongly exhibited in the epoxy resin composition, and the fluidity may be significantly reduced. Although the lower limit of the specific surface area is 0.2 m ² / g, it can be theoretically determined 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 calculated 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 required to be 15 m ² / g. However, in reality, if the specific surface area is less than 0.2 m ² / g and the geometrical calculation value above is tried to be approached, a step of thoroughly removing fine powder by classification operation such as screening is required, resulting in a significant cost increase. It leads to and becomes unrealistic.

When the epoxy resin composition is used in 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 those having a low content rate of radioisotope such as. In such cases, U or T of spherical amorphous silica or alumina
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. When these are contained in the epoxy resin composition, the adhesiveness at the interface between the cured product and the semiconductor chip and the 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
-Epoxycyclohexyl) ethyltrimethoxysilane and other epoxysilanes, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane , Γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane and other aminosilanes, 3-mercaptopropyltrimethoxysilane and other mercaptosilanes, p-styryltrimethoxysilane, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) ) Vinyl silanes such as silane, vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane, as well as epoxy-based, amino-based, vinyl-based polymer type silanes, etc. It can be, in particular, epoxy silane, amino silane, and mercapto silane are preferable.

On the other hand, as titanate coupling agents, isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl aminoethyl) titanate, diisopropyl bis (dioctyl phosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetra Octyl bis (ditridecyl phosphite) titanate, tetra (2,2-
Diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate and the like can be used.

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

Further, in the present invention, the compound represented by the above formula (B) or the compound represented by the above formula (C) is used as an additive in an amount of 0.01 to 0.01 based on the total amount of the epoxy resin composition.
It is preferable to contain 1% by mass. A more preferable content ratio is 0.05 to 0.5 mass%. The compound represented by the formula (B) is an alkyl polyether amine, such as hydroxyethyl lauryl amine, polyethylene glycol lauryl amine, polyethylene glycol stearyl amine, etc., and one having 1 to 10 ethylene glycol groups in one molecule. Can be used. On the other hand, the formula (C)
The compound represented by is a polyethylene glycol alkylphenol ether, such as polyethylene glycol nonylphenol ether or polyethylene glycol octylphenol ether, and polyethylene glycol having a chain length of 2 to 15 can be used. These compounds may be used alone, or 2
You may use together more than one kind.

Even if the compound represented by the above formula (B) or formula (C) is contained in the epoxy resin composition, it does not significantly affect the viscosity characteristics of the epoxy resin composition. This has the effect of increasing the penetration into the gap between the semiconductor chip and the circuit board in chip mounting and the fillet property. However, if the content of these compounds is less than 0.01% by mass, the effect of sufficiently enhancing the penetrability and filleting property may not be obtained, and conversely if the content exceeds 1% by mass, the infiltration Property and fillet property are not deteriorated, however, inconveniences such as deterioration of moisture resistance reliability and reduction of shelf life of the epoxy resin composition may occur.

Further, the epoxy resin composition may be mixed with other substances, 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 a defoaming agent.

In order to prepare a uniform liquid epoxy resin composition, the above-mentioned components are generally mixed by a stirring type disperser, a bead mill, or a three-roll dispersive mixture. However, the method 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 flip-chip structure semiconductor device for sealing, a semiconductor chip electrode and a circuit board electrode that 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 containing a fiber base material such as FR4 or FR5, or a build-up type organic substrate containing no fiber base material,
Furthermore, an organic film such as polyimide or polyester, an inorganic substrate such as alumina or glass, or the like can be used.

In order to infiltrate the liquid epoxy resin composition into the above-mentioned gap, it is important to take steps so as not to entrap air. As such a procedure,
It is common practice to apply the epoxy resin composition to one side or two sides of the semiconductor chip with a dispenser or the like, and to heat it to a temperature below the curing temperature, if necessary.
As a result, the epoxy resin composition infiltrates and fills the gap due to the capillary phenomenon, and a fillet is formed from the end portion of the semiconductor chip to the circuit board.
Then, in the present invention, the curing of the epoxy resin composition is performed 110
It is carried out at a temperature of ~ 180 ° C. At a low temperature of less than 110 ° C., curing is difficult to proceed, and thus the heat resistance of the epoxy resin composition becomes low, and the temperature cycle property after curing and the moisture resistance reliability may deteriorate. On the other hand, at a high temperature of more than 180 ° C., bubbles (voids) may be generated inside the cured product, which may also deteriorate the temperature cycle property after curing and the moisture resistance reliability.

Further, in the flip-chip structure semiconductor device for infiltrating the above-mentioned epoxy resin composition, the metal bumps of the semiconductor chip are formed of gold, and
The metal bumps and the electrodes of the circuit board bonded to each other through the conductive paste can be preferably used. Such a joining method is called stud bump bonding (SBB), and the metal bumps at this time are not formed by plating, but are formed as two-step protrusions (stud bumps) by ball bonding. Is.

As described above, since gold is used for the metal bumps instead of solder, the metal bumps can be formed by utilizing the ball bond producing function of the wire bonding apparatus. Further, the metal bumps with a narrow pitch can be formed, and since the metal bumps are formed as the two-step protrusions as described above, the spread of the conductive paste can be suppressed when the semiconductor chip and the circuit board are connected. It is possible. Further, when solder was used as the metal bump, flux removal work was required, but in SBB, since gold is used as the metal bump, the flux removal process is unnecessary.

On the other hand, the conductive paste in the present invention is not particularly limited, and for example, a conventionally known silver paste composed of silver powder as a metal powder, phenoxy resin as a thermosetting resin, and an organic solvent can be used. The conductive paste can be applied and dried in advance on the electrode surface of the circuit board before the semiconductor chip and the circuit board are joined.

As described above, in the SBB, the metal bump and the electrode of the circuit board are joined together 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, generally, a low-viscosity epoxy resin composition containing 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 main component is a liquid sealing material. However, when such a product is used, there is no electrical connection between the metal bump and the circuit board after curing, or the electrical resistance of the connection part is considerably large. However, there is a possibility that it will not be able to withstand actual use. Therefore, when the epoxy resin composition prepared in the present invention is used in place of the conventional encapsulant, it is possible to completely maintain the electrical continuity between the semiconductor chip and the circuit board after curing. The reason for this is not clear so far, but the liquid resin component containing the formula (A) swells and softens the once dried conductive paste to promote percolation (particle contact) of the conductive particles due to subsequent curing shrinkage. It is guessed that it is because it does.

[0059]

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

(Examples 1 to 19 and Comparative Examples 1 to 5) In Examples 1 to 19, the compounding amounts (parts by mass) shown in Tables 1 and 2 below, and in Comparative Examples 1 to 5, Epoxy resin compositions were prepared by mixing the components in the blending amounts (parts by mass) shown in Table 3 below using Disper (manufactured by Tokushu Kika Kogyo).

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

(Epoxy resin) Resin A: Bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Ltd., product number "Epicoat 828", epoxy equivalent 190) Resin B: Bisphenol A epoxy resin (Toto Kasei Co., product number "YD-8125", epoxy equivalent 17
2) Resin C: Bisphenol F type epoxy resin (manufactured by Tohto 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)) The alicyclic acid anhydride (the acid anhydride represented by the formula (A-2), manufactured by Yuka Shell Epoxy Co., Ltd., product number “YH-306”, which is synthesized from the indicated β-type of ocimene) and maleic anhydride. ,
Acid anhydride equivalent 234) Curing agent B: methylhexahydrophthalic anhydride (MHHP
A, manufactured by Dainippon Ink and Chemicals, Inc., product number “B-65
0 ", acid anhydride equivalent 168) (Curing accelerator) Curing accelerator A: Microcapsules containing imidazole as a core (manufactured by Asahi Kasei Kogyo Co., Ltd., product number" NOVACURE HX3 "
722 ") Curing accelerator B: amine adduct (manufactured by Ajinomoto Co., product number" Amicure PN23 ") (coupling agent) Coupling agent A: γ-glycidoxypropyltrimethoxysilane (manufactured by Nippon Unicar Co., product number" A-18
7 ") Coupling agent B: tetraisopropyl bis (dioctyl phosphite) titanate (manufactured by Ajinomoto Co., Inc., product number" KR-41B ") (Additive) Additive A: polyethylene glycol lauryl amine (represented by 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,
Nippon Oil & Fat Co., Ltd., product number "Nymeen S-210") Additive C: polyethylene glycol nonylphenol ether (compound represented by formula (C), n = 9, m = 4 or 5, Nippon Oil & Fat Co., Ltd. product number " Nonion NS-20
4.5 ") Additive D: polyethylene glycol octylphenol ether (compound represented by formula (C), n = 8, m =
6, manufactured by NOF CORPORATION, product number "NONION NH-20"
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)
Silica B: Spherical amorphous silica (manufactured by Admatex Co., product number “SO-E2”, maximum particle size 3 μm, average particle size 0.6 μm) Silica C: Spherical amorphous silica (manufactured by Tokuyama Corp., 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 ( Sumitomo Chemical Co., Ltd., product number “AA-2”, maximum particle size 7 μm,
Alumina B: spherical α-alumina (manufactured by Admatex Co., product number “AO-502”, maximum particle size 5 μm, average particle size 0.4 μm, true specific gravity 3.6). )

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

In Tables 1 to 3 above, the equivalent ratio (10
0 :) indicates the oxide equivalent to 100 epoxy equivalent, the filler volume% indicates the volume% of the inorganic filler in terms of true specific gravity, and the filler mass% indicates the inorganic filler in the epoxy resin composition. Shows the mass% of.

In calculating the volume percentage of the inorganic filler converted to true specific gravity, the true specific gravity of the resin components other than the filler is 1.2, and the true specific gravity of silicas A to D is 2.2, and Alumina A and alumina B in a mass ratio of 8: 2
With respect to the mixture (in the case of Example 2), the average specific gravity was set to 3.88.

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

(1) Viscosity of epoxy resin composition A rotor type rotary viscometer (manufactured by Brookfield, model "HBT", rotor symbol "SC") was used, and
The viscosity at ° C was measured.

(2) The semiconductor device used in the flip chip (FC) penetration test is an electrode on a FR5 grade circuit board and a CMOS (Complementary Metal-Oxide Semiconducto) chip size 0.4 mm thick and 10 mm square.
r) The electrode around the chip of the gate array element is 70
They are connected by solder bumps having a height of μm.
The epoxy resin composition is applied to the end of one side of this semiconductor chip with a dispenser, the circuit board is immediately placed on a hot plate of 60 ° C., and the side opposite to the side coated with the epoxy resin composition. The time to reach to was measured. Those with a time of 30 seconds or less are marked with "⊚", those with a duration of more than 30 seconds and 60 seconds or less are marked with "○", those with a duration of more than 60 seconds and less than 2 minutes are marked with "△", those with more than 2 minutes are marked with "x". It was judged.

(3) Fillet Property Regarding the semiconductor device evaluated for the penetrability of (2), it was observed how much fillet was formed between the end portion of the semiconductor chip and the circuit board. “⊚” if the same degree of fillets are formed on all four sides of the semiconductor chip, and “○” if the fillets are formed on all four sides of the semiconductor chip to different extents, and the epoxy resin composition is applied. If the fillet is not formed on the side opposite to the filled side and fillets are formed on the other sides, “△” is indicated, and fillets are formed on the sides other than the side coated with the epoxy resin composition. If not, it was judged as "x".

(4) Temperature Cycle (TC) Property Regarding the semiconductor device evaluated for penetrability of (2), the applied epoxy resin composition was cured by heat treatment under the following two conditions. Condition 1 is a temperature of 150 ° C. for 2 hours, and condition 2 is a temperature of 150 ° C. for 30 minutes. Then, 10 of the semiconductor devices after curing, which were found to be non-defective in the electrical operation confirmation result, were taken out as test samples under each condition. Then, for these test samples, -55 ° C
For 30 minutes, at room temperature for 5 minutes, at 150 ° C for 30 minutes, and at room temperature for 5 minutes as a cycle. A gas phase temperature cycle test is conducted, and operation of the semiconductor device is checked every 100 cycles up to 2000 cycles. It was 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) Moisture resistance reliability (PCT) resistance In the same manner as (4), 10 pieces of the semiconductor devices after the curing were cured under the conditions 1 and 2 were found to be non-defective. The test sample was used. And for these test samples, 121 ° C at 2 atm
Performs a pressure cooker test (PCT) of 100
Check the operation of the semiconductor device every 50 hours until 0 hours,
The quality was judged. Under each condition, the total processing time was calculated when the number of defects in 10 test samples reached more than half.

(6) The configuration of the SBB type semiconductor device used for the SBB initial connectivity test is 10
A 40 μm-high gold bump formed on an electrode in the peripheral portion of a chip of a CMOS gate array element having a size of mm square is connected to an electrode on a FR5 grade circuit board via a silver paste. The epoxy resin composition was infiltrated into this semiconductor device by the method described in (2), and the temperature was raised to 150 ° C.
After performing a curing treatment for 30 minutes, the operation of the semiconductor device was confirmed and the number of disconnection defects was obtained. Whether or not electrical continuity is secured in the gold bump and silver paste parts that connect the electrodes on the semiconductor chip side to the electrodes on the circuit board side depends on whether there is a disconnection defect in this operation check. You can

[0075]

[Table 4]

[0076]

[Table 5]

[0077]

[Table 6]

As shown in Tables 4-6, Examples 1-1
Comparing No. 9 with those of Comparative Examples 1 to 5, the viscosity of the epoxy resin composition of each of the Examples is low,
It is confirmed that the penetration and fillet properties are excellent.
Further, it is confirmed that the cured products of the respective examples are excellent in temperature cycle property and heat resistance reliability and can sufficiently secure the electrical connection reliability in SBB.

On the other hand, it was confirmed that all of the comparative examples had extremely poor temperature cycle property, heat resistance reliability and connection reliability in SBB, and were not put to practical use.

[0080]

As described above, the epoxy resin composition according to claim 1 of the present invention is an epoxy resin composition which is liquid at room temperature and contains an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler as essential components. In, at least one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a naphthalene type epoxy resin is contained as an epoxy resin, and an acid anhydride represented by the above formula (A) is contained as a curing agent. , As a curing accelerator, fine sphere particles obtained by coating a compound having an imidazole skeleton with a core and a coating of a thermosetting resin around the core, or containing at least one of amine adduct particles, and inorganic 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 in the epoxy resin composition in an amount of 10 to 60% by volume in terms of true specific gravity, the epoxy resin composition can penetrate into a narrow gap such as between a semiconductor chip and a circuit board. In addition to being easy to fill, it can be filled without containing bubbles, and at the end of the semiconductor chip, a fillet can be formed from this end to the circuit board. Moreover, the epoxy resin composition thus filled in the gap can be cured in a short time. Further, the cured product disperses the stress applied in the vicinity of the metal bumps, thereby preventing the metal bumps from being damaged such as cracks, and improving the temperature cycle property and the moisture resistance reliability. .

The invention of claim 2 uses the bisphenol A type epoxy resin having an epoxy equivalent of 180 or less as the epoxy resin in claim 1, so that the viscosity, the curability of the epoxy resin composition and the heat resistance of the cured product are high. In that case, it is possible to maintain a good balance of properties, hygroscopicity, etc., and in particular, it is possible to make the viscosity low and to express high fluidity, and it is possible to sufficiently secure the heat resistance of the cured product. is there.

The invention of claim 3 is the epoxy resin composition according to claim 1 or 2, wherein 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 heat resistance of the cured product and the strength such as the adhesive strength can be sufficiently secured, and the moisture absorption rate of the cured product can be suppressed to improve the moisture resistance reliability.

The invention of claim 4 uses the silane coupling agent or the titanate coupling agent as the coupling agent according to any one of claims 1 to 3, so that the cured product of the epoxy resin composition and the semiconductor chip are used. Also, the adhesiveness at the interface with the circuit board is improved, and the moisture resistance reliability of the semiconductor device can be improved.

A fifth aspect of the present invention is, in any one of the first to fourth aspects, a compound represented by the above formula (B) or a compound represented by the above formula (C) is added as an additive.
Since it is contained in an amount of 0.01 to 1% by mass based on the total amount of the epoxy resin composition, the epoxy resin composition can be more easily penetrated into the gap between the semiconductor chip and the circuit board in flip chip mounting, and the filleting property can be improved. It is something that can be done.

A semiconductor device according to a sixth aspect of the present invention is a semiconductor device manufactured by flip-chip mounting a semiconductor chip on a circuit board by bonding metal bumps formed on the semiconductor chip to the circuit board. The 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 the fillet portion extends from the end of the semiconductor chip to the circuit board. And the epoxy resin composition is heated and cured at 110 to 180 ° C., excellent temperature cycle property and moisture resistance reliability as a semiconductor device can be realized.

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

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI C08K 7/18 C08K 7/18 C08L 63/00 C08L 63/00 C H01L 21/56 H01L 21/56 E 23/29 23/30 R 23/31 (72) Inventor Hirohisa Hino 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor, Taro Fukui 1048, Kadoma, Kadoma, Osaka Prefecture, Matsushita Electric Works, Ltd. (56) References Open 2002-97257 (JP, A) JP 2001-288340 (JP, A) JP 4-351630 (JP, A) JP 5-9263 (JP, A) JP 3-281625 (JP, A) JP 2000-273152 (JP, A) JP 10-147717 (JP, A) JP 2001-31878 (JP, A) JP 7-316263 (JP, A) JP 5-17557 (JP, A) JP 9-235357 (JP, A) JP 7 −268079 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08G 59/42 C08G 59/40 C08L 63/00-63/10 C08K 3/22 C08K 3/36 C08K 5 / 06 C08K 7/18 H01L 21/56 H01L 23/29

Claims (7)

(57) [Claims] 1. An epoxy resin composition which is liquid at room temperature and contains, as essential components, an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler, and at least a bisphenol A type epoxy resin or a bisphenol F type epoxy resin as the epoxy resin. , Or a naphthalene-type epoxy resin as a curing agent, an acid anhydride represented by the following formula (A) as a curing agent, and a nucleus having a compound having an imidazole skeleton as a curing accelerator. Spherical amorphous material containing at least one of fine spherical particles and amine adduct particles obtained by coating the periphery of with a coating of a thermosetting resin, and having a maximum particle size of 0.5 to 20 μm as an inorganic filler. Quality silica or at least one of alumina having a maximum particle size of 0.5 to 10 μm is 1 in terms of true specific gravity with respect to the total amount of the epoxy resin composition. Epoxy resin composition characterized by containing 60% by volume. [Chemical 1] 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 of 80 or less is used. 3. The epoxy resin composition according to claim 1, wherein 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. 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. A compound represented by the following formula (B) or a compound represented by the following formula (C) as an additive is contained in an amount of 0.01 to 1% by mass based on the total amount of the epoxy resin composition. The epoxy resin composition according to any one of claims 1 to 4, characterized in that: [Chemical 2] 6. A semiconductor device manufactured by flip-chip mounting a semiconductor chip on a circuit board by bonding metal bumps formed on the semiconductor chip to the circuit board, and the semiconductor chip and the circuit board via the metal bump. The epoxy resin composition according to any one of claims 1 to 5 is filled in the gap formed between the two, and a fillet portion is formed from the end portion of the semiconductor chip to the circuit board,
A semiconductor device, characterized in that the epoxy resin composition is heated to 110 to 180 ° C. and cured. 7. A conductive paste composed of metal powder, a thermoplastic resin, and an organic solvent is applied to the surface of a circuit board and dried, and a metal bump formed of gold is bonded to the circuit board through the conductive paste. 7. The semiconductor device according to claim 6, wherein the semiconductor chip is mounted on a circuit board and manufactured.