JP2001240657A - Resin paste for semiconductor and semiconductor using the same paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paste capable of curing in both of an in-line curing method (hot plate curing, or HP curing) and a batch method (oven curing) which are generally used in producing ICs(integrated circuits), and having sufficient adhesive strength, low stressedness and a long pot life. SOLUTION: The paste for a semiconductor and made of a resin comprises (A) 100 pts.wt. of an epoxy resin, (B) 20-60 pts.wt. of a phenolic curing agent, (C) 0.5-5 pts.wt. of a latent curing agent, (D) a silane compound in an amount of 10-60 pts.wt. based on 100 pts.wt. of the total weight of the components (A), (B) and (C), (E) an organic borate (salt) in an amount of 0.5-20 pts.wt. based on 100 pts.wt. of the total weight of the components (A), (B) and (C), and (F) an inorganic filler as essential components.

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 In a process of bonding a semiconductor element to a metal frame, that is, a so-called die bonding step, it is necessary to mount the semiconductor element on the metal frame and then harden it by a method using a resin paste. Conventionally, curing by a batch method using an oven has been the mainstream. However, in recent years, a hardening furnace has been connected to the side of the die bonder that mounts semiconductor elements on a metal frame, and the die bonding, hardening, and wire bonding processes can be performed collectively on the same line, and an in-line method has been adopted to improve productivity. , There is a tendency to increase further.

On the other hand, in the in-line system, the curing device is much more expensive than the conventional oven-based system, and the in-line system and the batch system using the oven are often mixed in the same factory. In such a case, it is very difficult for inventory control and workers to use the resin paste for semiconductor element bonding for each of the in-line method, batch method, and curing method. There is a need for an adhesive resin paste.

In the in-line system, the curing time is more limited than in the conventional batch system. For example, the curing time in the conventional batch system is 150 to 200 ° C. for 60 to 120 minutes, but in the in-line system it is 150 to 200 ° C. 15-12
Must be 0 seconds. The difference between these curing conditions is due to the reactivity of a curing agent used for a resin paste for bonding semiconductor elements using an epoxy resin. In the case of a resin paste for semiconductor element bonding for in-line curing, which mainly cures in a short time, performance such as adhesive strength during oven curing is very poor compared to in-line curing. Conversely, in the oven-curing resin paste for bonding a semiconductor element, curing is not completed within the curing time restricted by the in-line method.

[0005] Therefore, a combination of oven curing and in-line curing has been a very difficult subject. Furthermore, in the case of in-line curing, since the temperature rises rapidly, air bubbles are generated in the resin paste, and problems such as a tilt of the semiconductor element and a decrease in the adhesive strength occur. In addition, as an adverse effect of increasing the curability, the reaction easily proceeds even at room temperature, and there is a problem that the pot life (pot life) is shortened.

[0006]

SUMMARY OF THE INVENTION The present invention can be cured by both in-line curing method (hot plate curing) and batch method (oven curing) which are common in IC manufacturing, and has sufficient adhesive strength and low stress. And a resin paste having a long pot life.

[0007]

Means for Solving the Problems (A) Epoxy resin,
(B) phenol curing agent, (C) latent curing agent, (D)
A silane compound represented by the general formula (1), (E) a formula (2)
And (F) an inorganic filler, wherein the component (B) is 2 parts per 100 parts by weight of the component (A).
0 to 60 parts by weight, 0.5 to 5 parts by weight of the component (C), and 10 to 60 parts by weight of the total of 100 parts by weight of the components (A), (B) and (C). Parts by weight, component (E)
Is from 0.5 to 20 parts by weight.

[0008]

Embedded image (R1 is an aliphatic or aromatic functional group having an epoxy group,
R2 represents an alkoxy group, and R3 represents an alkyl group or an alkoxy group. )

Embedded image

Further, the present invention is a semiconductor device manufactured using the above-mentioned resin paste for a semiconductor.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having an epoxy group. For example, crystalline epoxy resins such as bisphenol A, bisphenol F, phenol novolak, polyglycidyl ether obtained by the reaction of cresol novolaks with epichlorohydrin, biphenyl type epoxy resin, stilbene type epoxy resin, hydroquinone type epoxy resin, butanediol di Aliphatic epoxies such as aliphatic epoxies such as glycidyl ether and neopentyl glycol diglycidyl ether, heterocyclic epoxies such as diglycidyl hydantoin, vinylcyclohexenedioxide, dicyclopentadiene dioxide, and alicyclic diepoxy-adipate ,
Dicyclopentadiene-modified phenolic epoxy resin,
There are triphenol methane type epoxy resin, naphthol type epoxy resin, biphenyl aralkyl type epoxy resin and the like, and one or more of these can be used in combination. Although there are various types of epoxy resins depending on the molecular weight, those having a small molecular weight and being liquid at room temperature are preferable in terms of workability at the time of compounding and viscosity after compounding.

When the epoxy resin is solid or semi-solid, or when the viscosity is high even in a liquid state, it is preferable to use a reactive diluent having an epoxy group in combination. Those used as the reactive diluent include, for example, n-butyl glycidyl ether, glycidyl versatate,
There are styrene oside, ethylhexyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, butylphenyl glycidyl ether and the like, and 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 epoxy resin. 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 Examples include acidic initial condensates with aldehydes and acidic initial condensates of polyhydric phenols such as resorcin, catechol and hydroquinone with formaldehyde, and these may be used alone or as a mixture.

The amount of the phenol curing agent (B) is preferably 20 to 60 parts by weight based on the epoxy resin (A) from the viewpoint of adhesiveness and low stress.

The latent curing agent (C) used in the present invention is used as a curing agent for epoxy resins. 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 the epoxy resin (A). If the amount is less than 0.5 part by weight, the adhesive strength under heat is weak, and if it exceeds 5 parts by weight, the low stress property is reduced.

The silane compound (D) used in the present invention
Is represented by the general formula (1) and is used for imparting an action as a diluent and adhesiveness.

R1 in the general formula (1) is an aliphatic or aromatic functional group having an epoxy group. This is not preferred because an epoxy resin is used as a resin component, for example, a vinyl group other than an epoxy group, an amino group, a mercapto group or the like adversely affects compatibility and storage stability. Do not adversely affect these.
Since R2 is an alkoxy group, a sufficient adhesive strength is obtained after the paste is cured, and a non-alkoxy group cannot provide a sufficient adhesive strength. R3 may be an alkyl group or an alkoxy group, and if it is an alkoxy group, a stronger adhesive force can be obtained. Such silane compounds include, for example, γ
-Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 8- (3,4-epoxycyclohexyl) ethylmethoxysilane and the like. The compounding amounts of the silane compound (D) are: epoxy resin (A), phenol curing agent (B), latent curing agent (C)
Is preferably 10 to 60 parts by weight based on the total amount of 1
If the amount is less than 0 parts by weight, sufficient adhesive strength cannot be obtained, and if it exceeds 60 parts by weight, the low stress property decreases.

The organic borate salt (E) of the formula (2) used in the present invention is used as a curing accelerator, and is obtained as a salt of phosphoniums and tetraphenyl borate. If a non-salt with tetraphenylborate is used as a curing accelerator, the storage stability is extremely poor and the method is not practical. In particular, when the organic borate salt of the formula (2) is used, a resin paste having extremely excellent storability without impairing curability can be obtained. The compounding amounts of the organic borate salt (E) are as follows: epoxy resin (A), phenol curing agent (B), latent curing agent (C)
Is preferably used in an amount of 0.5 to 20 parts by weight based on the total amount of If the amount is less than 0.5 part by weight, sufficient curability cannot be obtained and 2
If it exceeds 0 parts by weight, the storage stability will be reduced.

Examples of the inorganic filler (F) used in the present invention include metal powders such as gold powder, silver powder, copper powder, and aluminum powder;
Examples include fused silica, crystalline silica, silicon nitride, aluminum nitride, talc, and the like. Among them, the metal powder is mainly used for imparting electrical conductivity or thermal conductivity. The filler used preferably has a content of ionic impurities such as halogen ions and alkali metal ions of 10 ppm or less. The shape may be a flake, scale, resin, or sphere. The particle size to be used varies depending on the required viscosity of the paste, but usually the average particle size is preferably 1 to 20 μm, and the maximum particle size is preferably about 50 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, and continuous use cannot be performed for a long time. It is also possible to use a mixture of relatively coarse and fine fillers,
Various shapes may be appropriately mixed.

Further, an inorganic filler other than the present invention may be used in order to impart required properties.

If necessary, additives such as pigments, dyes, defoamers, surfactants and solvents can be used in the resin paste of the present invention as long as the properties according to the intended use are not impaired. 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 a semiconductor of the present invention can be cured quickly, does not have a decrease in adhesive strength when heated, 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.

[0022]

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 5 and Comparative Examples 1 to 9> Each component having the composition shown in Table 1 and an inorganic filler were blended and kneaded with a three-roll mill to obtain a resin paste. After defoaming this resin paste at 2 mmHg for 30 minutes in a vacuum chamber,
Various performances were evaluated by the following methods. Table 1 shows the evaluation results.

<Raw Materials Used> Epoxy resin (A): bisphenol A type epoxy resin (BPA, viscosity 9000 mPa · s, epoxy equivalent 1)
85) ・ Reactive diluent: phenylglycidyl ether

Phenol curing agent (B): phenol novolak resin (PN, hydroxyl equivalent: 104) Latent curing agent (C): dicyandiamide (DDA) Silane compound (D): γ-glycidoxypropyltrimethoxysilane (Γ-GPTMS) ・ Organic borate salt represented by formula (2) (E) ・ Tetraphenylphosphonium ・ Tetraphenylborate salt (TPP-K) ・ Inorganic filler (F): Silver powder: Average particle size of 0.1 to 50 μm Flake-shaped silica filler with a particle diameter of 3 μm: silica filler with an average particle diameter of 5 μm and a maximum particle diameter of 20 μm

<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 is applied on a Teflon sheet to a width of 10 mm, a length of about 150 mm, and a thickness of 100 μm, and cured in an oven at 200 ° C. for 60 minutes.
The modulus of elasticity was calculated from the initial gradient of the stress-strain curve obtained by measuring at a stretching speed of 1 mm / min at a stretching speed of 00 mm. Adhesive strength: A 2 × 2 mm silicon chip was mounted on a copper frame using a paste, and cured at 200 ° C. for 60 seconds on a hot plate (HP curing) and in an oven at 200 ° C. for 60 minutes (OV curing). After curing, the die shear strength under heat at 25 ° C. and 250 ° C. was measured using a mount strength measuring device. Amount of warpage: A silicon chip of 6 × 15 × 0.3 mm is mounted on a copper frame (200 μm thick) with a conductive resin paste, and is heated at 200 ° C. for 60 seconds on a hot plate (HP hardening) and at 200 ° C. for 60 seconds using an oven. After curing in minutes (OV curing), the warpage of the chip was measured with a surface roughness meter (measuring length 13 mm). 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 1.5 times or more the initial viscosity was measured.

The evaluation results are shown in Tables 1 and 2.

[Table 1]

[0028]

[Table 2]

In Examples 1 to 5, excellent pastes having a hot adhesive strength, low stress (low elastic modulus, low warpage) and a long pot life were obtained. Comparative Examples 1, 3, and 5 were phenol novolak, respectively. Since the amounts of the curing agent, the latent curing agent, and the coupling agent were small, the adhesive strength was significantly reduced. Comparative Examples 2 and 8 are inferior in pot life because of a large amount of the phenol novolak curing agent and the organic borate salt of the formula (2). In Comparative Example 3, the content of the reactive diluent was large, and the adhesive strength was significantly reduced. In Comparative Examples 4 and 6, since the amounts of the latent curing agent and the coupling agent were large, the curing shrinkage was large, and chip cracks occurred. In Comparative Example 7, since the amount of the organic borate salt of the formula (2) was small, the quick-curing property was inferior, and the adhesive strength in hot-plate curing was reduced. Comparative Example 9 is inferior in pot life because the type of organic borate salt is different.

[0030]

According to the present invention, it is possible to cure both in-line curing method (hot plate curing) and batch method (oven curing) which are common in IC manufacturing, and sufficient adhesive strength.
A semiconductor resin paste having low stress and a long pot life can be provided. A semiconductor device manufactured using the semiconductor resin paste of the present invention is a semiconductor device having high productivity while maintaining the conventional characteristics.

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Claims (2)

[Claims] 1. An epoxy resin, (B) a phenol curing agent, (C) a latent curing agent, (D) a silane compound represented by the general formula (1), and (E) a silane compound represented by the formula (2). The organic borate salt and the inorganic filler (F) are essential components, and the component (B) is 20 to 60 parts by weight, and the component (C) is 0.5 to 5 parts by weight with respect to 100 parts by weight of the component (A). And 10 to 60 parts by weight of the component (D) and 0.5 to 2 parts by weight of the component (E) based on 100 parts by weight of the total of the components (A), (B) and (C).
A resin paste for semiconductors, which is 0 parts by weight. Embedded image (R1 is an aliphatic or aromatic functional group having an epoxy group,
R2 represents an alkoxy group, and R3 represents an alkyl group or an alkoxy group. ) 2. A semiconductor device manufactured using the resin paste for a semiconductor according to claim 1.