JP2001106767A - Resin paste for semiconductor and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin paste for a semiconductor, suitable for bonding a large-sized chip such as IC, etc., to a copper frame due to high bond strength in heating and excellent stress relaxation, capable of preventing defective characteristics of IC, etc., caused by chip crack, chip strain, etc., in an IC assembly process. SOLUTION: This resin paste for a semiconductor comprises a combination of two kinds of epoxy resins, a liquid phenol curing agent, a latent curing agent, a curing promoter being a tertiary amine salt and an inorganic filler. The epoxy resins are a liquid epoxy resin and an epoxy group-containing reactive diluent. This semiconductor device is produced by using the resin paste.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin paste for bonding a semiconductor element such as an IC or an LSI to a metal frame or the like.

[0002]

2. Description of the Related Art Recent remarkable developments in the electronics industry have evolved into transistors, ICs, LSIs, and ultra-LSIs. The integration of circuits in these semiconductor devices has rapidly increased, and mass production has become possible. With the spread of semiconductor products using these, improvement in workability and cost reduction in mass production have become important issues. Conventionally, semiconductor elements were replaced with Au-S
In general, they were joined by an eutectic method and then sealed by a hermetic seal to obtain a semiconductor product. However, in view of workability and cost during mass production, a resin encapsulation method has been developed and is now generally used. Along with this, a method using a solder material or a resin paste, that is, a mounting resin has come to be taken up as an improvement of the Au-Si eutectic method in the mounting step.

However, the solder method has low reliability,
The disadvantage is that the electrodes of the element are liable to be contaminated, and the use thereof is limited to power transistors and power IC elements that require high thermal conductivity. On the other hand, the mounting resin is superior in workability and reliability as compared with the soldering method, and the demand thereof is rapidly increasing.

Further, in recent years, the chip has been increased in size due to the increase in the degree of integration of ICs and the like. On the other hand, since the 42 alloy frame, which has been conventionally used, is expensive, copper is used for cost reduction purposes. Frames have come to be used. Here, the size of the chip such as IC is about 4
When it is larger than ~ 5 mm square, heating in the assembly process of IC etc., if the Au-Si eutectic method is used as the mounting method, chip cracks and cracks may occur due to the difference between the coefficient of thermal expansion of the chip and the coefficient of thermal expansion of the copper frame. Defective characteristics due to warpage have become a problem.

That is, the thermal expansion coefficient of silicon or the like as a chip material is 3 × 10 ⁻⁶ / ° C., whereas that of a 42 alloy frame is 8 × 10 ⁻⁶ / ° C. 20 × 10 ^-6
/ ° C. On the other hand, it is conceivable to use a mounting resin as the mounting method.However, with a conventional epoxy resin-based paste, since the thermosetting resin is three-dimensionally cured, the elastic modulus is high, and the distortion between the chip and the copper frame is reduced. Did not absorb.

If an epoxy resin which reduces the crosslink density during curing, for example, a resin containing a large amount of an epoxy monomer, is used, the modulus of elasticity can be lowered, but there is a disadvantage that the adhesive strength is reduced. Furthermore, ordinary epoxy resins have high viscosity, and if an inorganic filler is added to this, the viscosity will be too high, threading will occur at the time of dispensing, workability will deteriorate, and if a large amount of solvent is added to improve workability, There was a problem that voids were generated.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an IC which is not affected by chip cracks or warpage even in a combination of a large chip such as an IC and a copper frame without lowering the adhesive strength when heated.
It is an object of the present invention to provide a resin paste which does not cause poor properties such as the above, is fast-curing, and does not generate voids.

[0008]

SUMMARY OF THE INVENTION The present invention aims at lowering the elastic modulus of a cured product without lowering the adhesive strength during heating.
The weight ratio of the liquid epoxy resin represented by the general formula (1) to the liquid epoxy resin represented by the general formula (2) is 5:95.
(A) epoxy resin, (B) a liquid phenol resin represented by the general formula (3), (C) a latent curing agent, and (D) a curing accelerator which is a tertiary amine or a salt thereof. And (E) an inorganic filler, wherein component (B) is 10 to 30 parts by weight, component (C) is 0.5 to 5 parts by weight, and component (A) is 100 parts by weight of component (A). ,
Component (D) is added to 100 parts by weight of the total of (B) and (C).
Is from 0.1 to 10 parts by weight. Further, the present invention is a semiconductor device manufactured using the above-mentioned resin paste for a semiconductor.

[0009]

Embedded image

Embedded image

Embedded image

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin (A) used in the present invention has a weight ratio of the liquid epoxy resin represented by the general formula (1) to the liquid epoxy resin represented by the general formula (2) of 5: 95-80. : 20 (A) epoxy resin. There are various types of liquid epoxy resins represented by the general formula (1) depending on the molecular weight, but those having a small molecular weight and being liquid at room temperature are preferable in view of workability at the time of compounding and viscosity after compounding.

In a weight ratio between the liquid epoxy resin represented by the general formula (1) and the liquid epoxy resin represented by the general formula (2), 9 parts of the liquid epoxy resin represented by the general formula (2) is used.
If it exceeds 5, the stress characteristics deteriorate, and if it is less than 20, the adhesive strength decreases.

In the present invention, other epoxy resins may be mixed and used. Other epoxy resins when mixed with the above epoxy resin include, for example, phenol novolak, polyglycidyl ether obtained by the reaction of cresol novolaks with epichlorohydrin, fats such as butanediol diglycidyl ether, neopentyl glycol diglycidyl ether and the like. Heterocyclic epoxies such as aliphatic epoxy, diglycidyl hydantoin, alicyclic epoxies such as vinylcyclohexene dioxide, dicyclopentadiene dioxide, alicyclic diepoxy-adipate, and one or more of these And can be used together.

Liquid epoxy resin (A) for improving workability
May be mixed with a reactive diluent having an epoxy group.
Examples of the reactive diluent having an epoxy group include, for example, n-butyl glycidyl ether, glycidyl versatate, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, butylphenyl glycidyl ether, and the like. One or more of these can be used in combination.

The phenol curing agent (B) used in the present invention is used as a curing agent for an epoxy resin. The phenol curing agent (B) used in the present invention is a liquid novolak type phenol resin obtained by a reaction of allylphenol / formaldehyde resin, and is preferably a liquid at normal temperature from the viewpoint of workability.

In the present invention, other phenol resins may be mixed and used. The phenol curing agent used in the present invention desirably has two or more active hydrogen groups per molecule which react with epoxy groups and participate in crosslinking. Examples of such phenol compounds include bisphenol A, bisphenol F, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol S, dihydroxydiphenyl ether, dihydroxybenzophenone, o-hydroxyphenol, m-hydroxyphenol, Strong acidity in dilute aqueous solution with monohydric phenols such as p-hydroxyphenol, biphenol, tetramethylbiphenol, ethylidenebisphenol, methylethylidenebis (methylphenol), hexidylhexylidenebisphenol, phenol, cresol, xylenol, etc. in dilute aqueous solution Phenol novolak resin obtained by reacting under the following conditions, monofunctional phenols and polyfunctional such as acrolein and glyoxal Initial condensate under acidity with aldehydes,
Acidic initial condensates of polyhydric phenols such as resorcin, catechol and hydroquinone with formaldehyde, and the like, and these may be used alone or as a mixture.

The amount of the phenol curing agent (B) to be used is preferably 10 to 30 parts by weight based on the epoxy resin (A) from the viewpoint of adhesiveness and low stress. If the blending amount of the phenol curing agent (B) is less than 10 parts by weight with respect to the epoxy resin (A), there is a problem that the adhesive strength is weak and it is not practical.
When the amount exceeds 30 parts by weight, there is a problem that the low stress property is remarkably reduced, and bleed out is easily caused.

The latent curing agent (C) used in the present invention is used as a curing agent for an epoxy resin. Dicyandiamide. When a latent curing agent is used, the adhesive strength when heated becomes significantly higher than when cured with a phenol curing agent alone. Further, since the latent curing agent has a smaller equivalent weight than the phenol curing agent, it is possible to obtain a paste which is not so high in viscosity when used in combination and which has excellent preservability due to the latent curing agent.

The compounding amount of the latent curing agent (C) is preferably 0.5 to 5 parts by weight based on all epoxy resins. 0.5
If the amount is less than 5 parts by weight, the adhesive strength at heat is weak, and if it exceeds 5 parts by weight, the low stress property is undesirably reduced.

The curing accelerator (D) used in the present invention comprises a third
Secondary amine or a salt thereof, dimethylbenzylamine,
It is preferably a salt of at least one tertiary amine selected from the group consisting of tris (dimethylaminomethyl) phenol, alicyclic superbases and imidazoles with phenols or basic acids. Examples of the alicyclic superbase include trimethylenediamine, 1,8-diazabicyclo (5,4,0) undecene-7, dodecahydro-1,4,7,9b tetraazaphenalene and the like.

The imidazoles include, for example, 2- and
/ Or methyl on the position of the 4-ethyl, propyl or more long chain alkyl groups of up to C _17, it is obtained by introducing a substituent such as a phenyl group. Those which form salts with these tertiary amines include phthalic acid (o, m, p), tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid,
Hexahydrophthalic acid, trimellitic acid, adipic acid,
Basic acids such as succinic acid, maleic acid and itaconic acid, or phenols such as resorcinol, pyrogallol, hydroquinone, phenol, bisphenol A, bisphenol F, bisphenol S, and low molecular weight novolak.

These tertiary amine salts are desirably used in an amount of 0.1 to 10 parts by weight based on the total amount of the epoxy resin (A), the phenol curing agent (B), and the latent curing agent (C). . If the amount is less than this, the accelerated curing is insufficient, and if the amount is more than this, the curing is not so accelerated but the storage stability may be undesirably reduced.

The inorganic filler (F) used in the present invention includes silver powder and silica filler. Silver powder is used to impart conductivity, and the content of ionic impurities such as halogen ions and alkali metal ions is preferably 10 ppm or less. The shape of the silver powder may be flake, resin, sphere or the like. The particle size of the silver powder to be used varies depending on the required viscosity of the paste, but usually the average particle size is preferably 2 to 10 μm, and the maximum particle size is preferably about 50 μm. In addition, a mixture of relatively coarse silver powder and fine silver powder can be used, and various shapes may be appropriately mixed.

The silica filler used in the present invention has an average particle size.
It has a maximum particle size of 50 μm or less with a size of 1 to 20 μm. If the average particle size is less than 1 μm, the viscosity increases, and if the average particle size exceeds 20 μm, bleeding occurs because the resin component flows out during coating or curing, which is not preferable. If the maximum particle size exceeds 50 μm, the outlet of the needle is blocked when applying the paste with a dispenser, so that long-time continuous use cannot be performed. Further, a mixture of a relatively coarse silica filler and a fine silica filler may be used, and various shapes may be appropriately mixed. Further, an inorganic filler other than the present invention may be used in order to impart required properties.

The resin paste of the present invention may contain a silane coupling agent, a titanate coupling agent, a pigment, a dye, a defoaming agent, a surfactant, a solvent, etc., as long as the properties according to the intended use are not impaired. Additives can be used. The production method of the present invention includes, for example, premixing the components, kneading using a three-roll mill or the like to obtain a paste, and then defoaming under vacuum.

The semiconductor device manufactured by using the resin paste for semiconductors of the present invention can be cured rapidly, does not have a decrease in thermal bonding strength, and has no warpage even in a combination of a large chip and a copper frame. A highly reliable semiconductor device can be obtained. A known method can be used for manufacturing a semiconductor device using a resin paste for a semiconductor.

[0026]

EXAMPLES The present invention will be specifically described with reference to Examples. The mixing ratio of each component is part by weight. <Examples 1 to 9 and Comparative Examples 1 to 9> Each component having the composition shown in Tables 1 and 2 was mixed with an inorganic filler, and kneaded with a three-roll mill to obtain a resin paste. After defoaming the resin paste at 2 mmHg for 30 minutes in a vacuum chamber, various performances were evaluated by the following methods. The evaluation results are shown in Tables 1 and 2.

<Raw ingredients used> Liquid epoxy resin represented by general formula (1) Bisphenol F type epoxy resin (BPFEP): viscosity 5000 mPa · s, epoxy equivalent 170 ・ liquid epoxy resin glycidyl represented by general formula (2) Amine type epoxy resin (GAEP): viscosity 1500 mPa · s, epoxy equivalent 100

Phenol curing agent (B): Liquid allylated phenol novolak (LPN): Viscosity 2000 mPa · s, phenol equivalent 140 • Latent curing agent (C): Dicyandiamide (DDA) • Curing accelerator (D): 1,8-diazabicyclo (5,4,0) undecene-7 (DBU)-Inorganic filler (F): Silver powder: Flaky silica filler having a particle size of 0.1 to 50 µm and an average particle size of 3 µm: Maximum with an average particle size of 5 µm Silica filler with a particle size of 20μm

<Evaluation method> Viscosity: 25 ° C. using an E-type viscometer (3 ° cone);
The value at 5 rpm was measured and defined as viscosity. Elastic modulus: A paste having a width of 10 mm, a length of about 150 mm and a thickness of 100 μm is applied on a Teflon (registered trademark) sheet,
After curing in an oven at 200 ° C. for 30 minutes, the modulus of elasticity was calculated from the initial slope of the stress-strain curve obtained by measuring with a tensile tester a test length of 100 mm and a pulling rate of 1 mm / min. Adhesive strength: A 2 × 2 mm silicon chip was mounted on a copper frame using a paste and cured in an oven at 200 ° C. for 30 minutes. After curing, the die shear strength under heat at 25 ° C. and 250 ° C. was measured using a mount strength measuring device. Chip warpage: A 6 × 15 × 0.3 mm silicon chip was mounted on a copper frame (200 μm thick) with a conductive resin paste, cured at 200 ° C. for 20 minutes, and then cracks due to chip warpage were observed. Pot life: The number of days until the viscosity when the resin paste was allowed to stand in a thermostat at 25 ° C. increased to 1.2 times or more the initial viscosity was measured.

[0030]

[Table 1]

[0031]

[Table 2]

In Examples 1 to 9, excellent pastes having a hot adhesive strength, low stress properties (low elastic modulus, low warpage) and a long pot life can be obtained. In Comparative Example 1, the amount of the glycidylamine type epoxy resin is large. And the low stress property was poor, the amount of warpage was large, and chip cracks occurred. In Comparative Example 2, the amount of the glycidylamine type epoxy resin was small, and the adhesive strength was significantly reduced. In Comparative Example 3, the amount of the liquid phenol resin was small, and the adhesive strength was significantly reduced. In Comparative Example 4, the amount of the liquid phenol resin was large, and chip cracks occurred. In Comparative Example 5, the amount of the latent curing agent was small, and the adhesive strength was low. In Comparative Example 6, the amount of the latent curing agent was large, the amount of warpage was large, and chip cracks occurred.
In Comparative Example 7, the amount of the curing accelerator was small, and the adhesion strength was significantly reduced. In Comparative Example 8, the amount of the curing accelerator was large, and the pot life was significantly shortened.

[0033]

The resin paste for semiconductors of the present invention has a high adhesive strength when heated and an excellent stress relaxation property.
It is suitable for bonding large-sized chips such as
Characteristic defects such as ICs due to chip cracks and chip distortion in the assembly process can be prevented. In addition, rapid curing is possible and there is no generation of voids. A semiconductor device manufactured using this paste has high reliability and high productivity.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C09J 161/10 C09J 161/10 163/00 163/00 163/02 163/02 H01L 21/52 H01L 21/52 EF Term (reference) 4J002 CC043 CC053 CD05W CD13X DA078 DJ018 EN037 EN107 EQ026 ET006 EU097 EU117 FD018 FD146 FD157 GQ05 4J036 AA05 AD08 AE07 AJ15 DA04 DA06 DA10 DC05 DC10 DC11 DC13 DC31 DC35 DC41 DC46 FA07 FA05 EB07 EC06 EC06 EC06 EC06 HC04 HC09 HC15 HC18 HC23 HC24 JA05 JB10 KA03 KA16 KA17 KA32 KA42 LA05 LA06 LA11 MA02 NA20 5F047 AA11 BA23 BA34 BA35 BA51 BA53 BB11

Claims (2)

[Claims] (A) an epoxy resin wherein the weight ratio of the liquid epoxy resin represented by the general formula (1) to the liquid epoxy resin represented by the general formula (2) is 5:95 to 80:20;
(B) a liquid phenolic resin represented by the general formula (3),
(C) a latent curing agent, (D) a curing accelerator that is a tertiary amine or a salt thereof, and (E) an inorganic filler, wherein component (B) is 10 to 10 parts by weight of component (A). 30
Parts by weight, the component (C) is 0.5 to 5 parts by weight, and the total of the components (A), (B) and (C) is 100 parts by weight,
A resin paste for a semiconductor, wherein the component (D) is 0.1 to 10 parts by weight. Embedded image Embedded image Embedded image 2. A semiconductor device manufactured using the resin paste for a semiconductor according to claim 1.