JP3018685B2 - Adhesive for semiconductor element and semiconductor device - Google Patents

Abstract

PURPOSE:To obtain adhesive which can join a semiconductor element to a support member without using silver paste at a low temperature in a short time by incorporating epoxy resin, dicyandiamide, novolac phenol resin, special imidazoles and ultrafine particle silica filler. CONSTITUTION:The adhesive for a semiconductor element comprises (1) epoxy resin, (2) dicyandiamide, (3) novolac phenol resin, (4) imidazoles represented by a formula (I), (5) imidazoles represented by a formula (5), and (6) ultrafine particle silica filler. The quantities of the ingredients (2)-(5) are set to 2-9mol%, 5-15mol%, 3-10mol% and 1.5-5mol% to (1). In the formula, R1 is an alkyl group or a phenyl group, R2 is an alkyl group or hydroxymethyl group, R3 is hydrogen, cyanoethyl group or 2, 4-diamino-6-ethyl-s-triazine group, and R4, R5 are alkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for a semiconductor element and a semiconductor device, and more particularly, to an adhesive for a semiconductor which can reduce the number of steps and cost and can obtain a highly reliable semiconductor device. And a semiconductor device using the same.

[0002]

2. Description of the Related Art Conventionally, as a method of bonding a semiconductor element to a lead frame (supporting member) when manufacturing a semiconductor device, there are (1) a method using an inorganic material such as a gold-silicon eutectic as an adhesive, 2) There is a method in which silver powder or the like is dispersed in an organic material such as an epoxy resin or a polyimide resin to form a paste, which is used as an adhesive. However, the former method is expensive and requires 350 to 40.
Recently, high heat treatment of about 0 ° C is required, and the adhesive is hard and the chip is broken by thermal stress.
The latter method using silver paste has become mainstream. In this method, a silver paste is generally applied to a lead frame using a dispenser or a stamping machine, and then the semiconductor element is die-bonded and cured by heating to join. As the method of heat curing, there are a batch method of curing in an oven and an in-line method of curing on a heated plate.

In the case of the former batch method, a long curing time of 1-2 hours at 150-180 ° C. is required for an epoxy resin-based paste, and 1-2 hours at 180-300 ° C. for a polyimide resin-based paste. On the other hand, in the case of the latter in-line method, the curing time is as short as 30 to 120 seconds.
It is necessary to heat at a high temperature of 50 ° C. For this reason, the solvent and the reactive diluent contained in the paste volatilize in a short period of time, and voids are apt to remain in the cured paste, thereby lowering the adhesive strength, causing the semiconductor element to float, and causing the semiconductor element to become volatile due to volatile components. There is a disadvantage that the surface of the semiconductor device is contaminated and the reliability of the semiconductor device is reduced.

In recent years, as the size of integrated circuit (IC) devices has increased, copper has been increasingly used for lead frames in order to improve the heat dissipation of the devices. in this case,
When the paste is hardened and cooled at a high temperature of 230 to 350 ° C., the warpage of the IC element increases due to the thermal stress caused by the difference in the linear expansion coefficient between the IC element and the lead frame during cooling, and the heat history during the wire bonding increases the IC element. Cracks are likely to occur not only in the element but also in the die bonding material, which has the disadvantage of significantly reducing the reliability of the semiconductor device. Furthermore, when an epoxy resin-based paste is used, there is a problem that a trace chlorine compound in the cured product is eluted by moisture in the air and corrodes the aluminum electrode of the semiconductor element, thereby significantly reducing the moisture resistance reliability. Was. further,
In the past, some semiconductor devices such as MOS memories and MOS logics do not require conductivity as an adhesive,
Although it was not necessary to use an expensive silver paste, no other inorganic filler excellent in terms of the sedimentation property of the filler and the change in coating properties with time could not be found, so the silver paste was used.

[0005]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned disadvantages of the prior art and provides an adhesive for a semiconductor element which can bond a semiconductor element and a supporting member at a low temperature in a short time without using a silver paste. An object of the present invention is to provide a highly reliable semiconductor device in which the generation of voids in a cured adhesive layer, the elution of a chlorine compound due to warpage of a semiconductor element, moisture and the like using the same, and the use of the same.

[0006]

According to the present invention, there are provided (1) an epoxy resin, (2) a dicyandiamide, (3) a novolak type phenol resin, and (4) a general formula (I).

Embedded image (Where R ₁ represents an alkyl group or a phenyl group, and R ₂ represents an alkyl group or a hydroxymethyl group), (5) a general formula (II)

Embedded image (Where R ₃ is hydrogen, cyanoethyl group or 2,4-
Wherein the diamino-6-ethyl-s-triazine group, R ₄ and R ₅ represent the same or different alkyl groups) and (6) an ultrafine silica-based filler; The amount of the component (5) is adjusted to 2 to 9 mol%, 5 to 15
The present invention relates to an adhesive for a semiconductor element having a molar percentage of 3 to 10 mol% and 1.5 to 5 mol%, and a semiconductor device in which a semiconductor element is bonded to a supporting member using the adhesive for a semiconductor element. Examples of the epoxy resin (1) used in the present invention include bisphenol A, bisphenol F,
Epoxy resin, phenol novolak resin derived from bisphenol AD or the like and epichlorohydrin, o-
An epoxy resin derived from cresol novolak resin, polyhydric phenol resin and the like and epichlorohydrin, and the like can be mentioned. There is no particular limitation on the molecular weight of the epoxy resin, but if the molecular weight is large, the viscosity becomes high. Therefore, it is preferable to adjust the viscosity with a reactive diluent or the like. As the reactive diluent, for example, phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether and the like are used. The amount of the diluent used is preferably as small as possible from the viewpoint of reducing the generation of voids in the cured product.

Dicyandiamide (2) used in the present invention is a latent curing agent having excellent storage stability and curability. The amount of dicyandiamide used is 2 to 9 mol%, preferably 3 to 5 mol%, based on the epoxy resin. If the amount used is less than 2 mol%, elution of chlorine compounds in the cured epoxy resin cannot be prevented, and 9 mol%
If it exceeds 300, the chlorine compound is easily extracted into water, corrosion of the aluminum electrode of the semiconductor element is promoted, and the humidity resistance reliability of the semiconductor device is significantly reduced.

The novolak-type phenolic resin (3) used in the present invention is obtained by subjecting phenol and / or its derivative to formaldehyde to a condensation reaction in the presence of an acidic catalyst. The novolak-type phenol resin acts as a curing agent together with the dicyandiamine (2), and has a function of preventing a chlorine compound in the cured epoxy resin from being eluted into water. The amount of the novolak-type phenol resin used is 5 to 15 mol%, preferably 7 to 12 mol%, based on the epoxy resin. If the used amount is less than 5 mol%, the chlorine compound in the cured product is easily eluted into water. If the used amount exceeds 15 mol%, the viscosity of the paste increases remarkably, and it is necessary to add a large amount of a reactive diluent.
Voids in the cured product increase.

The imidazoles (4) represented by the general formula (I) used in the present invention include 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethyl Examples thereof include imidazole, and the amount of the imidazole is 3 to 10 mol%, preferably 4 to 7 mol%, based on the epoxy resin. When the amount of the imidazoles is less than 3 mol%, the curability is remarkably reduced, and
If it exceeds mol%, the storage stability and the conductivity of the cured product will be significantly reduced.

The imidazoles (5) represented by the general formula (II) used in the present invention include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, -Undecylimidazole and the like, and the amount of use is 1.5 to 5 mol%, preferably 2 to 4 mol%, based on the epoxy resin. If the amount of the imidazoles is less than 1.5 mol%, the curability is poor, and if it exceeds 5 mol%, the storage stability decreases. Imidazoles (5) are mainly used as a curing accelerator for the dicyandiamide and novolak-type phenolic resins.

The ultrafine silica filler (6) used in the present invention includes, for example, Aerosil RY-200 (trade name, manufactured by Nippon Aerosil Co., Ltd.). The compounding amount is preferably 1 to 5% by weight of the total weight of the adhesive from the viewpoint of workability. The adhesive for a semiconductor element of the present invention comprises, for example, heating the epoxy resin (1), a reactive diluent used as required, and a novolak-type phenol resin (3) in a flask at a temperature of 80 to 120 ° C. Dissolve to form a varnish, and add the dicyandiamide (2) and the general formula (I)
Obtained by mixing an imidazole (4) represented by the following formula, an imidazole (5) represented by the general formula (II), and an ultrafine silica filler (6) with, for example, a three-roll mill or a crusher. .

A semiconductor device is obtained by bonding a semiconductor element to a support member using the adhesive for a semiconductor element according to the present invention. The semiconductor device is preferably obtained by, for example, applying the adhesive to a support member and mounting the semiconductor element thereon, and then heating and curing the plate on a plate heated to 150 to 180 ° C. for 30 to 120 seconds. Within this temperature range and heating time, voids are less likely to occur in the adhesive, and in-line curing becomes possible.

[0013]

The present invention will be described below in more detail with reference to examples. Example 1 1 mol of bisphenol F type epoxy resin (trade name YDF170 manufactured by Toto Kasei Co., Ltd., epoxy equivalent: about 175) and novolak type phenol resin (trade name H-1 manufactured by Meiwa Kasei Co., Ltd.)
0.1 mol was heated and melted in a flask at 100 ° C. to form a varnish, to which 3 mol% of dicyandiamide (mol% based on epoxy resin, the same applies hereinafter), 6 mol of 2-phenyl-4-methyl-5-hydroxymethylimidazole % And 2 mol% of 2-ethyl-4-methylimidazole were kneaded with a three-roll mill to obtain a base resin for an adhesive.

Example 2 1 mol of bisphenol AD epoxy resin (trade name: R-710, manufactured by Mitsui Petrochemical Co., Ltd., epoxy equivalent: about 170) and 0.1 mol of novolak phenol resin H-1 were added at 100 ° C. in a flask. The mixture was heated and dissolved to form a varnish, to which 5 mol% of dicyandiamide and 2-phenyl-4-methyl-5 were added.
6 mol% of -hydroxymethylimidazole and 3 mol% of 1-cyanoethyl-2-ethyl-4-methylimidazole were kneaded with a three-roll mill to obtain a base resin for an adhesive.

Example 3 Trifunctional epoxy resin (TACT, trade name, manufactured by Dow Chemical Company)
IX-742, epoxy equivalent of about 160) 1 mol, novolak type phenolic resin H-1, 0.06 mol and pt-butylphenylglycidyl ether 0.02 mol were heated and dissolved in a flask at 100 ° C. to form a varnish. Dicyandiamide 5 mol%, 2-phenyl-4,5-
Dihydroxyimidazole (5 mol%) and 1-cyanoethyl-2-ethyl-4-methylimidazole (3 mol%) were kneaded with a three-roll mill to obtain an adhesive base resin.

Comparative Example 1 1 mole of bisphenol F type epoxy resin YDF170 (epoxy equivalent: about 175) and 0.1 mole of novolak type phenol resin H-1 were heated and dissolved at 100 ° C. in a flask to form a varnish, and dicyandiamide was added thereto. 12 mol%,
6 mol% of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 2 mol% of 2-ethyl-4-methylimidazole were kneaded with a three-roll mill to obtain a base resin for an adhesive.

Comparative Example 2 7 mol% of dicyandiamide, 6 mol% of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 2 mol% of 2-ethyl-4- were added to 1 mol of bisphenol F type epoxy resin YDF170 (epoxy equivalent: about 175). 2 mol% of methyl imidazole was kneaded with a three-roll mill to obtain a base resin for an adhesive.

Comparative Example 3 1 mol of bisphenol F type epoxy resin YDF170 (epoxy equivalent: about 175) and 0.1 mol of novolak type phenol resin H-1 were heated and dissolved at 100 ° C. in a flask to form a varnish, and dicyandiamide was added thereto. 5 mol% and 2 mol% of 2-phenyl-4-methyl-5-hydroxymethylimidazole were kneaded with a three-roll mill to obtain a base resin for an adhesive.

<Test Examples> Examples 1 to 3 and Comparative Examples 1 to
3 g of Aerosil RY-200 (manufactured by Nippon Aerosil Co., Ltd.) was kneaded with 100 g of the base resin for adhesive obtained in 3 with a three-roll mill to prepare an adhesive for semiconductor elements. The following evaluation was performed using the obtained adhesive, and the results are shown in Table 1. (1) Evaluation of Adhesive Strength Silver plating island 2 on copper lead frame 1 having 2.5 mm × 2.5 mm silver plating island 2 shown in FIG. As shown in FIG. 2, about 120 μg of the adhesive 4 was applied thereon, and then a 2 mm × 2 mm × 0.25 mmt silicon wafer 3 was placed thereon, and then pressed with tweezers so that the paste 4 slightly protruded around the wafer 3. After, 170 ° C
A hardening treatment was performed for 60 seconds on a hot plate heated to obtain a test piece. Using a push-pull gauge (manufactured by Aiko), the test piece was peeled off the wafer at 23 ° C. and 300 ° C., and the adhesive strength was measured.

(2) Evaluation of voids After applying 5 mg of paste to the surface silver-plated copper frame 5 and the island portion 6 shown in FIG. 3, 10 mm × 10 mm ×
A silicon wafer of 0.35 mmt was press-bonded and heat-cured on a hot plate at 170 ° C. for 60 seconds. After observing voids with a microscope, the occupied area of the voids was estimated. (3) Extraction of the cured product 15 g of the adhesive was spread on a Teflon plate of 20 cm x 20 cm with a metal spatula to a thickness of about 1 mm, cured for 1 hour in a 170 ° C oven, peeled off the cured product from the Teflon plate and crushed with a crusher. After finely crushing, the mixture was sieved through a 100 mesh sieve to obtain a sample for extraction. 10 g of the sample and 50 g of deionized water were put in a 50 ml Teflon bottle, sealed, extracted in an oven at 120 ° C. for 20 hours, filtered, and the chloride ion concentration of the filtrate was measured by ion chromatography.

[0021]

[Table 1] From the results in Table 1, it is shown that in Examples 1 to 3, a high adhesive strength was obtained at a low temperature and in a short time, and the chlorine ion concentration in the extraction water was low.

[0022]

According to the adhesive for semiconductor elements of the present invention,
The semiconductor element and the lead frame can be cured at a low temperature and in a short time without using a silver paste. Further, by using this adhesive, the manufacturing process of the semiconductor device can be shortened, the generation of voids in the adhesive layer can be suppressed, and the material cost can be reduced.
Furthermore, since the concentration of chlorine ions in the extraction water of the cured product can be reduced, the reliability of the semiconductor device, particularly, the reliability of moisture resistance can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a frame for evaluating an adhesive force.

FIG. 2 is a sectional view of a frame to which a wafer is bonded.

FIG. 3 is a schematic view of a frame for evaluating voids.

[Explanation of symbols]

1: Copper lead frame, 2: Silver plating island,
3. Silicon wafer, 4. Adhesive, 5. Surface silver plated copper frame, 6. Island part.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuo Ichimura 4-3-1-1, Higashicho, Hitachi City, Ibaraki Prefecture Inside the Yamazaki Plant of Hitachi Chemical Co., Ltd. (72) Yasuo Miyamoto 4--13 Higashimachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Plant (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/52

Claims (2)

(57) [Claims] 1. An epoxy resin, (2) dicyandiamide, (3) a novolak-type phenol resin, and (4) a general formula (I). (Where R ₁ represents an alkyl group or a phenyl group, and R ₂ represents an alkyl group or a hydroxymethyl group), (5) an imidazole represented by the following general formula (II): (Where R ₃ is hydrogen, cyanoethyl group or 2,4-
Wherein the diamino-6-ethyl-s-triazine group, R ₄ and R ₅ represent the same or different alkyl groups) and (6) an ultrafine silica-based filler; The amount of the component (5) is adjusted to 2 to 9 mol%, 5 to 15
An adhesive for a semiconductor element comprising 3 mol%, 3 to 10 mol% and 1.5 to 5 mol%. 2. A semiconductor device comprising a semiconductor element bonded to a support member using the semiconductor element adhesive according to claim 1.