JPH08245765A - Compound semiconductor device - Google Patents

Abstract

PURPOSE: To obtain the subject device, responsive to the shortening of an assembly step and saving of energy and having high reliability by bonding and fixing a compound semiconductor chip and a lead frame with a specific electroconductive paste. CONSTITUTION: This device is obtained by bonding and fixing a semiconductor chip and a lead frame with an electroconductive paste consisting essentially of (A) a modified resin comprising (i) an epoxy resin and (ii) a sulfonium salt of formula I (X is CH3 , H, a halogen or NO2 ; M is Sb, As or P) or formula II (R<1> and R<2> are each an alkyl, a halogen or H; R<3> is an ether or an ester; A<-> is SbF6 <-> , AsF6 <-> , PF6 <-> or CH3 SO4 <-> ), (B) an electroconductive filter (e.g. silver powder) and (C) a solvent, a monomer or a mixture thereof (e.g. Methyl Cellosolve). Furthermore, the sulfonium salt in the component (ii) is preferably blended in an amount of 0.5-20 pts.wt. based on 100 pts.wt. component (i).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a conductive paste having excellent moisture resistance, adhesiveness, low-temperature curing property, and rapid curing property for mounting a compound semiconductor chip, and is capable of shortening the assembly process of a semiconductor device. The present invention relates to a compound semiconductor device.

[0002]

2. Description of the Related Art In a semiconductor device, a conductive adhesive layer for adhering a semiconductor chip such as an LED, an IC or an LSI to a predetermined portion on a thin metal plate (lead frame) has an important structure which affects long-term reliability of the element. one of. Conventionally,
As a method for adhering a silicon semiconductor chip, the Au-Si eutectic method has been mainstream, in which the silicon surface of the semiconductor chip is heat-pressed to the gold-plated surface on the lead frame. However, in recent years, the soaring price of precious metals, especially gold, has led to a rapid shift from the Au-Si eutectic method to the method of using solder and the method of using conductive paste (adhesive) in resin-molded semiconductor devices. is there.

[0003]

However, although the method of using solder has been partially put into practical use, there is a possibility that solder or solder balls may scatter and adhere to electrodes or the like, resulting in corrosion disconnection. It has been pointed out. On the other hand, in the method using a conductive paste, an epoxy resin mixed with silver powder is usually used, and it has been put to practical use for about 15 years. However, from the viewpoint of reliability, Au-Si eutectic in a silicon semiconductor is used. No satisfactory results were obtained compared to the eutectic method for forming alloys. When using a conductive paste, it has the advantage of superior heat resistance compared to the solder method, but on the other hand, since the resin and its curing agent are not created for bonding semiconductor elements, the aluminum electrode In many cases, it promotes corrosion of aluminum and causes disconnection failure, and the reliability of the element is Au-Si.
It was inferior to the eutectic method. Furthermore, in recent years, due to the reliability of small semiconductor chips, the adhesive strength has decreased and chip peeling has become a problem. Aiming to shorten the assembly process and improve mass productivity, conductive paste with fast curing and strong adhesive strength Further, there has been a strong demand for the development of a semiconductor device using a conductive paste that can be cured at a low temperature in order to prevent chip warpage and surface oxidation of a copper alloy frame.

The present invention has been made in view of the above circumstances, and is a highly reliable compound which is excellent in heat resistance, adhesiveness and moisture resistance, can be cured at low temperature and can be cured at high speed, and can be shortened in the assembly process. It is intended to provide a semiconductor device.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using a conductive paste having a composition described later, The present invention has been completed.

That is, the present invention relates to (A) an epoxy resin (a) and (b) a sulfonium salt represented by the following general formula (1) or (2):

[0007]

Embedded image A modified resin comprising (B) a conductive powder and (C) a conductive paste containing a solvent, a monomer or a mixture thereof as an essential component, and bonding and fixing the compound semiconductor chip and the lead frame. And a compound semiconductor device.

The present invention will be described in detail below.

The conductive paste used in the present invention is (a)
It contains (A) a modified resin consisting of an epoxy resin and (b) the sulfonium salt represented by the above chemical formula 2, (B) a conductive powder and (C) a solvent, a monomer or a mixture thereof as an essential component. Each of these components will be described.

As the epoxy resin (a) which is one component of the (A) modified resin, for example, Epicoat 827, 828,
834, 1001, 1002, 1007, 1009 (manufactured by Shell Chemical Co., trade name), DER330, 331, 33
2,334,335,336,337,383,660
(Dow Chemical Company, trade name), Araldite GY2
50, 260, 280, 6071, 6084, 609
7,6099 (Ciba Geigy, trade name), EPI-
REZ510, 5101 (manufactured by JONE DABNY, trade name), Epiclon 810, 1000, 101
0,3010 (manufactured by Dainippon Ink and Chemicals, Inc., trade name),
Asahi Denka Co., Ltd. EP series etc. are mentioned. Further, by using an epoxy resin having an average number of epoxy groups of 3 or more, for example, a novolac epoxy resin, it is possible to further improve the heat resistance of the paste cured product or the coating film, the room temperature adhesive strength, and the adhesive strength when heated (350 ° C). . As these novolac epoxy resins, those having a molecular weight of 500 or more are suitable. As the novolac epoxy resin, for example, Araldite EPN1138, 1139, ECN1273, 1
280, 1299 (Ciba Geigy, trade name), DE
N431,438 (trade name, manufactured by Dow Chemical Co., Ltd.), Epicoat 152,154 (trade name, manufactured by Shell Chemical Co., Ltd.),
ERR-0100, ERRB-0447, ERRB-0
488 (Union Carbide, product name), EOCN
The series (trade name, manufactured by Nippon Kayaku Co., Ltd.) and the like can be mentioned, and these can be used alone or in combination of two or more.

As the (b) sulfonium salt which is another component of the modified resin, the one represented by the above chemical formula 2 is used. This sulfonium salt is activated when heated,
The cationic species or Lewis acid is generated, and the epoxy resins are ring-opening polymerized by a cationic polymerization mechanism. Specific compounds of the sulfonium salt include, for example,

[0012]

Embedded image

[0013]

[Chemical 4]

[0014]

Embedded image Etc., and these can be used alone or in combination. The mixing ratio of sulfonium salt is epoxy resin
It is desirable to add 0.5 to 20 parts by weight to 100 parts by weight. If the blending amount is less than 0.5 parts by weight, it will not be practically cured because it does not cure rapidly and the curing rate is lowered. If the amount exceeds 20 parts by weight, the storage stability of the paste will be poor, and the Lewis acid remaining in the cured paste will deteriorate the electrical characteristics under high humidity conditions and corrode lead frames and aluminum wiring (electricity). It is unfavorable due to lack of reliability such as eating.

The above-mentioned (a) epoxy resin and (b) sulfonium salt are dissolved and mixed in a solvent or a monomer, or heated and reacted to partially bond with each other to obtain a modified resin.

Examples of the (B) conductive powder used in the present invention include silver powder, copper powder, nickel powder, carbon,
Examples thereof include powders having a metal layer on the surface, and these may be used alone or in combination of two or more.

The solvent or monomer (C) used in the present invention dissolves the modified resin of (A) and adjusts and improves the working viscosity of the paste. Specific solvents include, for example, dioxane, hexane, toluene, methyl cellosolve, cyclohexane, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, diethylene glycol dimethyl ether, dimethylformamide, N-methylpyrrolidone, diacetone alcohol, dimethylacetamide, γ-butyrolactone. , 1,3-dimethyl-2-imidazolidinone, etc., which may be used alone or in combination of two or more. Further, as the monomer, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether,
p-sec-butylphenyl glycidyl ether, glycidyl methacrylate, t-butylphenyl glycidyl ether, diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane triglycidyl ether,
Examples thereof include 1,6-hexanediol diglycidyl ether, and these can be used alone or in combination of two or more. Further, a solvent and a monomer may be mixed and used. When a solvent is used for the purpose of low temperature and fast curing, it is necessary to select a solvent having a low boiling point in accordance with the conditions such as curing temperature and curing time.

The conductive paste used in the present invention contains the above-mentioned modified resin, conductive powder and solvent or monomer as essential components, but as long as it does not defeat the purpose of the present invention, and if necessary, a defoaming agent and a cup. A ring agent and other additives can be added. This conductive paste can be manufactured by thoroughly mixing the above-mentioned components in a conventional manner, further kneading with, for example, a three-roll mill, and then degassing under reduced pressure. The conductive paste thus manufactured is filled in a syringe, discharged onto a lead frame using a dispenser, and after bonding the semiconductor chip by low temperature curing or high speed curing, wire bonding is performed and sealing is performed with a resin sealing material. A resin-sealed compound semiconductor device can be manufactured.

[0019]

The compound semiconductor device of the present invention is excellent in handleability in the manufacturing process as compared with the conventional semiconductor device by using the conductive paste which can be cured at low temperature and high speed and has excellent storage stability. In addition, the frame does not oxidize during curing and the chip warpage is small. Also, the adhesive strength is sufficient for bonding the semiconductor chip and the lead frame, it has little moisture absorption, and is excellent in moisture resistance, particularly bias PCT, PCT, etc. showing reliability of the semiconductor device.

[0020]

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 100 parts of epoxy resin Epicoat 1004 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) was dissolved in 100 parts of methyl cellosolve at 100 ° C. for 1 hour to obtain a viscous resin. 30 parts of this resin 0.20 of the sulfonium salt shown in Chemical formula 3
Parts, 0.02 parts of additives and 60 parts of silver powder were mixed and further kneaded with a three-roll mill to produce a conductive paste (A).

Example 2 Epoxy resin EOCN103S (manufactured by Nippon Kayaku Co., trade name) 70 parts, Epicoat 1001 (produced by Yuka Shell Epoxy Co., trade name) 30 parts, diethylene glycol diethyl ether 80 parts and toluene 20 parts 100 in a mixed solvent
A viscous resin was obtained by carrying out a dissolution reaction at ℃ for 1 hour. This resin
To 26.2 parts, 0.14 parts of the sulfonium salt represented by Chemical formula 4, 0.10 parts of an additive, and 60 parts of silver powder were mixed, and further kneaded with a three-roll mill to produce a conductive paste (B).

Example 3 15 parts of YL-983U (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), 3 parts of YL-980 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), t-butylphenyl glycidyl ether 10.0 Part, 0.20 part of the sulfonium salt represented by Chemical formula 5,
0.05 parts of the additive and 60 parts of silver powder were mixed and further kneaded with a three-roll mill to produce a conductive paste (C).

Comparative Example A commercially available epoxy resin-based conductive paste (D) for semiconductors was obtained.

Using the conductive pastes (A), (B), (C) and (D) obtained in Examples 1 to 3 and Comparative Example,
4 × 12 mm silicon chips were bonded and fixed on a lead frame (copper-based) having a thickness of 200 μm under the semiconductor element bonding conditions shown in Table 1 to manufacture compound semiconductor devices. These compound semiconductor devices were tested for adhesive strength, chip warpage, moisture resistance bias PCT, and PCT. The results are shown in Table 1, and the present invention was excellent in all cases, and the remarkable effect of the present invention was recognized.

[0026]

[Table 1] * 1: A 4 × 12 mm GaAs chip was bonded onto a 200 μm thick lead frame (copper-based), cured under the above specified conditions, and then measured at 350 ° C using a push-pull gauge. * 2: The surface of the chip after curing was measured with a surface roughness meter, and the distance between the center and the end of the chip was measured. * 3: Moisture resistance test (PCT) in steam with a temperature of 121 ° C and pressure of 2 atm, and humidity resistance test (bias PCT) with steam with an applied voltage of 1.5 V in steam at a temperature of 121 ° C and pressure of 2 atm. The semiconductor device was evaluated. The number of semiconductor devices subjected to the moisture resistance test was 60, and the number of defectives over time was shown. The defect was judged to be defective when the aluminum electrodes that compose the semiconductor device were opened due to corrosion or the leakage current increased to more than 500% of the allowable value.

[0027]

As is clear from the above description and Table 1, the compound semiconductor device of the present invention is excellent in adhesive strength and moisture resistance, and by using a conductive paste capable of low temperature curing and high speed curing. In addition, there is little warpage, and there is no disconnection failure due to corrosion of the aluminum electrode, which is highly reliable. Further, since low temperature curing and high speed curing are possible, it is possible to shorten the assembly process and save energy.

Claims (1)

[Claims] 1. (A) (a) epoxy resin and (b)
A sulfonium salt represented by the following general formula (1) or (2): A modified resin comprising (B) a conductive powder and (C) a conductive paste containing a solvent, a monomer or a mixture thereof as an essential component, and bonding and fixing the compound semiconductor chip and the lead frame. And a compound semiconductor device.