JPH0940929A - Compound semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a compd. semiconductor device with a high reliability by bonding a compd. semiconductor chip to a lead frame with an insulating paste prepd. by compounding an epoxy resin modified with a specific sulfonium salt with an insulating powder, etc. SOLUTION: This compd. semiconductor device is produced by bonding and fixing a compd. semiconductor chip to a lead frame with an insulating paste which comprises a modified resin (A) obtd. from an epoxy resin and a sulfonium salt represented by formula I(wherein X is methyl, H, etc.; and M is Sb, As, or P) or formula II (wherein R<1> and R<2> are each an alkyl, a halogen, or H; R<3> is a residue of an ether or ester; and A is SbF6 , AsF6 , PF6 , or CH3 SO4 ), an insulating powder (B), and a solvent or a monomer or a mixture thereof (C). As the epoxy resin, a novolak epoxy resin having an average epoxy functionality of 3 or higher is suitable for improving the heat resistance and adhesive strength. Pref. 100 pts.wt. epoxy resin is compounded with 0.5-20 pts.wt. sulfonium salt. Ingredient C is used for dissolving ingredient A and adjusting the viscosity of the resultant paste. The paste does not corrode an aluminum electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an insulating paste excellent in moisture resistance, adhesiveness, low temperature curing property, fast curing property, etc. for mounting a compound semiconductor chip, and is used in a semiconductor device assembly process. The present invention relates to a compound semiconductor device corresponding to the shortening of

[0002]

2. Description of the Related Art In a semiconductor device, a process of connecting a semiconductor chip such as an LED, an IC or an LSI to a predetermined portion on a thin metal plate (lead frame) is one of the important processes that affect the long-term reliability of the device. is there. Conventionally, as this connection method, there are a brazing method using a low melting point alloy (solder), a method using a conductive paste (adhesive), and the like. Further, in recent years, not only the conductive paste but also the insulating paste has come to be used due to the design of the semiconductor device.

[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 of using a conductive paste, usually, an epoxy resin mixed with silver powder is used, and in the case of an insulating paste, an epoxy resin mixed with silica powder is used. It has been put to practical use. However, in terms of reliability, a satisfactory result was not obtained as compared with the eutectic method for producing an Au-Si eutectic alloy in a silicon chip.

When these resin pastes are used, they have advantages such as excellent heat resistance as compared with the soldering method, but on the other hand, since the resin and its curing agent are not prepared for bonding semiconductor elements. In many cases, it promotes corrosion of the aluminum electrode and causes defective disconnection, and the reliability of the device was inferior to that of the Au-Si eutectic method. Furthermore, in recent years, due to the reliability of small semiconductor chips, the adhesive strength has deteriorated and chip peeling has become a problem. With the aim of shortening the assembly process and improving mass productivity, insulating paste with fast curing and strong adhesive strength Further, there has been a strong demand for the development of a semiconductor device using an insulating 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 has excellent adhesiveness, moisture resistance, heat resistance, low temperature curing and high speed curing, and a highly reliable compound capable of responding to shortening of the assembly process. It is intended to provide a semiconductor device.

[0006]

As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by using an insulating paste having a composition described later, The present invention has been completed.

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

[0008]

Embedded image A compound semiconductor chip and a lead frame are bonded and fixed using a conductive resin containing (B) an insulating powder and (C) a solvent, a monomer or a mixture thereof as an essential component. And a compound semiconductor device.

The present invention will be described in detail below.

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

Examples of (a) epoxy resin which is one component of (A) modified resin include 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,

[0013]

Embedded image

[0014]

Embedded image

[0015]

Embedded image And the like, and these can be used alone or as a mixture. 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 part by weight, the rapid curing property is not effective and the curing speed is lowered, which is not practical. 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) insulating powder used in the present invention include powders of crystalline silica, fused silica, fine silica, talc, aluminum hydroxide, calcium carbonate, bentonite, boron, etc., which may be used alone or 2
A mixture of two or more species can be used.

The solvent (C) or monomer used in the present invention dissolves the modified resin (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 insulating paste used in the present invention contains the above-mentioned modified resin, insulating powder and solvent or monomer as essential components, but as long as the object of the present invention is not impaired, a defoaming agent and a cup may be added if necessary. A ring agent and other additives can be added. This insulating paste can be manufactured by thoroughly mixing the above-mentioned components according to a conventional method, further kneading with, for example, a three-roll mill, and then degassing under reduced pressure. The insulating paste thus manufactured is filled in a syringe, discharged onto a lead frame using a dispenser, the semiconductor chip is bonded by low temperature curing or high speed curing, and then wire bonding is performed to seal with a resin encapsulant. A resin-sealed compound semiconductor device can be manufactured.

[0020]

The compound semiconductor device of the present invention is superior in handleability in the manufacturing process as compared with the conventional semiconductor device by using the insulating paste which can be cured at low temperature and high speed and has excellent storage stability. In addition, there is no oxidation of the frame during curing and there is little warpage of the chip. 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.

[0021]

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 of 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, additive 0.02 parts and fused silica powder (average particle size 5
(40 μm) were mixed and further mixed with a disperser and stirred to produce an insulating 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
26.2 parts of sulfonium salt shown in Chemical formula 4 0.14 parts, additive 0.10 parts and fused silica powder (average particle size 5 μm) 30
The parts were mixed, and further mixed and stirred with a disperser to produce an insulating paste (B).

Example 3 Epoxy resin YL-983U (Yukaka Shell Epoxy Co., trade name) 15 parts, YL-980 (Okaka Shell Epoxy Co., trade name) 3 parts, t-butylphenyl glycidyl ether 10.0 Part, 0.20 part of the sulfonium salt represented by Chemical formula 5,
0.05 parts additive and fused silica powder (average particle size 5 μm
) 40 parts were mixed and further mixed with a disperser and stirred to produce an insulating paste (C).

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

Using the insulating 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. As shown in Table 1, the present invention was excellent, and the remarkable effects of the present invention were recognized.

[0027]

[Table 1] * 1: A 4 × 12 mm silicon 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.

[0028]

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 the insulating paste capable of low temperature curing and high speed curing. In addition, it has high reliability because there is no disconnection failure due to corrosion of the aluminum electrode. 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 compound semiconductor chip and a lead frame are bonded and fixed by using an insulating paste containing a modified resin consisting of (B) an insulating powder and (C) a solvent, a monomer or a mixture thereof as an essential component. And a compound semiconductor device.