JP2501819B2 - Semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor device which is excellent in reliability, particularly humidity resistance reliability, and in which stress applied to a semiconductor element is small.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are usually sealed with a ceramic package or a plastic package to form a semiconductor device. The above-mentioned ceramic package has heat resistance and moisture permeation resistance of the constituent material itself, and therefore it is resistant to temperature and humidity, and since it is a hollow package, it has high mechanical strength and highly reliable sealing. It is possible. However, since the constituent materials are relatively expensive and the mass productivity is inferior, the resin sealing using the plastic package has recently become the mainstream. An epoxy resin composition has been conventionally used for this type of resin encapsulation, and has achieved good results. However, due to technological innovation in the field of semiconductors, the degree of integration has been increased, the element size has been increased, and the wiring has become finer, and the packages have also tended to be smaller and thinner. On the other hand, there is a demand for further improvement in reliability (internal stress, humidity resistance, shock resistance, heat resistance, and the like of the obtained semiconductor device).

[Problems to be solved by the invention]

That is, the epoxy resin composition used for semiconductor encapsulation generates considerable internal stress due to shrinkage in the process of cooling from the curing temperature to room temperature, and due to this internal stress, the crack of the passivation film of the semiconductor element or the crack or the crack of the semiconductor element itself. There are problems such as characteristic deterioration and, in some cases, cracking of the sealing resin itself.

In order to solve such a problem, conventionally, by mixing an organopolysiloxane in an epoxy resin composition or by compounding synthetic rubber particles, a low stress of a sealing resin made of the above cured epoxy resin composition is obtained. It is trying to make it. However, in such a case, although the stress applied to the element is reduced, there is a drawback that the moisture resistance of the semiconductor device is deteriorated due to the influence of the ionic impurities and hydrophilic groups contained in the organopolysiloxane and the synthetic rubber itself. Has occurred.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a semiconductor device which is excellent in moisture resistance reliability and has a small stress applied to the semiconductor element itself.

[Means for solving problems]

In order to achieve the above object, the semiconductor device of the present invention encapsulates a semiconductor element using an epoxy resin composition containing the following (A) to (D) as essential components and (E) as an optional component. Take the configuration.

(A) Epoxy resin.

(B) a phenolic resin.

(C) tetra-substituted phosphonium / tetra-substituted borate,
At least one boron compound selected from the group consisting of tetra-substituted ammonium / tetra-substituted borate, tetra-substituted arsonium / tetra-substituted borate and tetra-substituted borate of imidazole compound.

(D) Sb ₂ O ₅ · 4H ₂ O.

(E) Organopolysiloxane.

That is, the inventors of the present invention first conducted research on an epoxy resin composition system containing no organopolysiloxane for the purpose of improving the moisture resistance of the encapsulating resin composed of the cured epoxy resin composition. As a result, it was found that it is effective to use the special boron compound as the component (C) and Sb ₂ O ₅ .4H ₂ O as the component (D) together in order to improve the moisture resistance. Then, as a result of further research, when these were blended with a conventional epoxy resin composition for the purpose of reducing stress, not only low stress but also encapsulating resin excellent in moisture resistance was obtained. I found that. In particular, when organopolysiloxane is used as the stress-reducing component, such a stress-reducing effect and a moisture resistance improving effect become remarkable.

The semiconductor device of the present invention comprises an epoxy resin (A component), a phenol resin (B component), a special boron compound (C component), and Sb ₂ O ₅ .4H ₂ O (D component) as essential components, and an organopolysiloxane. (E component) is an optional component.

The epoxy resin of the component A is not particularly limited, and various epoxy resins such as cresol novolak type, phenol novolak type and bisphenol A type which have been conventionally used as sealing resins for semiconductor devices are used. . Among these resins, those having a melting point over room temperature and exhibiting a solid state or a high-viscosity solution state at room temperature bring about good results. As the novolak type epoxy resin, in addition to a typical cresol novolak type epoxy resin, an alkylated phenol novolak type epoxy resin obtained by adding various alkyl groups such as tert-butyl group and methyl group to the phenol portion is generally used. As these novolak type epoxy resins, those having an epoxy equivalent of 160 to 300 and a softening point of 50 to 130 ° C. are preferred.

The phenol resin of the component B used together with the epoxy resin (component A) acts as a curing agent for the epoxy resin, and contains phenol novolac, cresol novolak and other alkyl groups such as methyl group and tert-butyl group. An alkylated phenol novolac resin or the like added to the phenol portion is preferably used. These novolak resins have a softening point of 50-110 ° C and a hydroxyl equivalent of 7
It is preferable to use one of 0 to 180.

The mutual use ratio of the epoxy resin (component A) and the phenol resin is appropriately selected depending on the relationship between the epoxy equivalent and the hydroxyl equivalent, and the equivalent ratio of the phenolic hydroxyl group to the epoxy group is preferably in the range of 0.5 to 1.5. This is because if it deviates from this range, it becomes difficult to obtain a sufficient reaction.

The special boron compound of the component C used together with the epoxy resin of the component A and the phenol resin of the component B is a tetra-substituted phosphonium / tetra-substituted borate, a tetra-substituted ammonium / tetra-substituted borate, a tetra-substituted arsonium, a tetra-substituted borate, various imidazole compounds. (This compound also includes a derivative of an imidazole compound) tetra-substituted borate. These may be used alone or in combination.

As the tetra-substituted phosphonium tetra-substituted borate, tetrabutyl phosphonium tetraphenyl borate, n- butyl triphenyl phosphonium tetraphenyl borate, tetraphenyl phosphonium tetraphenyl borate, trimethyl phenyl phosphonium
Tetraphenylborate, diethylmethylphenylphosphonium / tetraphenylborate diallylmethylphenylphosphonium / tetraphenylborate, (2-hydroxylethyl) triphenylphosphonium / tetraphenylborate, ethyltriphenylphosphonium / tetraphenyl Examples thereof include borate, p-xylenebis (triphenylphosphonium.tetraphenylborate), tetraphenylphosphonium.tetraethylborate, tetraphenylphosphonium.triethylphenylborate, and tetraphenylphosphonium.tetrabutylborate. Further, as tetra-substituted arsonium tetra-substituted borate, tetramethyl arsonium
Examples thereof include tetraphenylborate, tetraphenylarsonium.tetraphenylborate, dimethyldiethylarsonium.tetraphenylborate, triethyl-n-octylarsonium.tetraphenylborate and the like. Further, as tetra-substituted ammonium / tetra-substituted borate, triethylamine / tetraphenylborate, trimethylamine / tetraphenylborate, triphenylamine / tetraphenylborate, diethylmethylamine / tetraphenylborate, diphenylmethylamine / tetraphenyl Examples include enilborate. Furthermore, as tetra-substituted borate of imidazole compound and its derivative, imidazole tetraphenyl borate, 2-ethyl-4-methylimidazole tetraphenyl borate, 1-cyanoethyl-2-ethyl-4-
Methylimidazole tetraphenylborate, 1-cyanoethyl-2-undecylimidazole tetraphenylborate, 1-cyanoethyl-2-phenylimidazole tetraphenylborate, 2-undecylimidazole tetraphenylborate, 2 -Hepdadecyl imidazole tetraphenylborate, 1-ethyl-
2-ethylimidazole, tetraphenylborate and the like can be mentioned.

 The general formulas for these are as follows.

 Tetra-substituted phosphonium / tetra-substituted borate.

Tetra-substituted arsonium / tetra-substituted borate.

Tetra-substituted ammonium / tetra-substituted borate.

Tetra-substituted borates of imidazole compounds.

The boron compound as the component (C) is used as an anon trapping agent, but also functions as a curing accelerator. It is also possible to use a conventionally known curing accelerator together with the C component. Like this (C)
The content of the components is 0.1 to 4% by weight based on the total amount of the epoxy resin composition of the component (A) and the phenol resin of the component (B).
(Hereinafter abbreviated as "%") is set.
It is preferably in the range of 0.5 to 3%. If the content of the component (C) is less than 0.1%, the ion trap effect will be insufficient, and if it exceeds 4%, the storage stability of the epoxy resin composition will be deteriorated.

The component (D), Sb ₂ O ₅ .4H ₂ O, is a component that effectively traps cations such as sodium ions present in the epoxy resin composition. As the component (D), for example, AHK-600 manufactured by Toagosei Co., Ltd. is commercially available. The amount of the component (D) used is preferably set to 0.1 to 20% of the total amount of the epoxy resin of the component (A) and the phenol resin of the component (B), and more preferably 0.3 to Ten
It is within the range of%. This is because if the amount of component (D) used is less than 0.1%, the ion trap effect will be insufficient, and if it exceeds 20%, it will tend to adversely affect various properties other than moisture resistance.

Further, the organopolysiloxane of the component (E) used together with the components (A) to (B) is an optional component and is used as necessary. Such an organopolysiloxane exerts the effect of reducing the internal stress of the sealing resin as described above, and has the following general formula (1): It is preferable to use the one represented by In particular, it is preferable to use a random copolymer as the above organopolysiloxane. However, there is no problem even if the organopolysiloxane represented by the general formula (1) and the other organopolysiloxane are used in combination. Further, in place of the organopolysiloxane represented by the general formula (1), both ends of the molecular chain have a methyl group, a carboxyl group,
Liquid polydimethylsiloxane having an amino group or an epoxy group may be used. The blending amount of the organopolysiloxane is preferably set to be 1 to 50% with respect to the total amount of the components (A) and (B). Most preferred is 5 to 30%. That is, when the blending amount of the organopolysiloxane is less than the above range,
This is because a sufficient stress-reducing effect cannot be obtained, and conversely, when the stress exceeds the above range, a phenomenon in which the resin strength is reduced will be observed.

In addition to the above-mentioned raw materials, the epoxy resin composition used in the present invention may optionally include a release agent, an inorganic filler, a curing accelerator, an antimony trioxide, a flame retardant such as a phosphorus compound, a pigment, and a silane coupling agent. Can be used.

Examples of the releasing agent include long-known carboxylic acids such as stearic acid and palmitic acid, zinc stearate, metal salts of long-chain carboxylic acids such as calcium stearate, and waxes such as carnauba wax and montan wax. A class can be used.

Further, the above-mentioned inorganic filler is not particularly limited, and commonly used quartz glass powder, talc,
Silica powder, alumina powder, etc. are appropriately used.

As the curing accelerator, various conventionally used curing accelerators can be used in addition to the component (C), and they can be used together. Preferred examples of this type of curing accelerator include the following tertiary amines, quaternary ammonium salts, imidazoles and boron compounds.

Tertiary amine triethanolamine, tetramethylhexanediamine, toluethylenediamine, dimethylaniline, dimethylaminoethanol, diethylaminoethanol, 2,4,
6- (dimethylaminomethyl) phenol, N, N'-dimethylpiperazine, pyridine, picoline, 1,8-diaza-
Bicyclo (5,4,0) undecene-7, benzyldimethylamine, 2- (dimethylamino) methylphenol quaternary ammonium salt dodecyltrimethylammonium iodide, cetyltrimethylammonium chloride, benzyldimethyltetradecylammonium chloride, stearyltrimethylammonium chloride Imidazoles 2-methylimidazole, 2-undecylimidazole, 2-ethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole boron compound tetraphenylboron, tetraphenylborate, N
-Methylmorpholine tetraphenylborate Incidentally, compounds other than the above may be used as long as they are compounds generally used as a curing accelerator for epoxy resins and phenol resins.

The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, (A)
Component epoxy resin, (B) component phenol resin, (C) component boron compound, and (D) component Sb ₂ O ₅ · 4H ₂ O
And, if necessary, the organopolysiloxane of the component (E) and a curing accelerator, a release agent, a filler, and other additives are blended according to a conventional method, and the mixture is put on a kneading machine such as a mixing roll machine. . Then, it can be produced by a series of steps of melt-mixing this in a heated state and, if necessary, tableting.

The encapsulation of the semiconductor using such an epoxy resin composition is not particularly limited and can be performed by a known molding method such as transfer molding.

The thus-obtained semiconductor device has extremely excellent moisture resistance reliability, and particularly when the organopolysiloxane of the component (E) is used, it exhibits excellent moisture resistance reliability and excellent low stress. become.

〔The invention's effect〕

As described above, the semiconductor device of the present invention has the above (C)
Special boron compound of component and Sb ₂ O ₅・ 4H ₂ O of component (D)
It is sealed with a special epoxy resin composition containing, and since the sealing resin is rich in moisture resistance, it has excellent moisture resistance reliability. Furthermore, when a cured epoxy resin composition containing an organopolysiloxane as an optional component is used as a sealing resin, it has excellent low stress property in addition to the above-mentioned moisture resistance reliability, and is added to the semiconductor element itself. Extremely low stress. Therefore, by encapsulating with the above-mentioned special epoxy resin composition, it is possible to sufficiently cope with encapsulation of semiconductor elements such as super LSI, ultra super LSI,
An extremely reliable semiconductor device can be obtained.

 Next, examples will be described together with comparative examples.

[Examples 1 to 6 and Comparative Examples 1 to 6] The raw materials shown in Table 1 below were blended in the proportions shown in the same table. In this case, in addition to the above raw materials, as the inorganic filler, 70% of the total amount of fusible SiO ₂ , 2% of the total amount of Sb ₂ O ₃ , 0.3% of the total amount of carbon, and 0.5% of the total amount of carnauba wax were mixed. Next, this mixture was kneaded with a hot roll at 120 ° C. for 5 minutes, cooled, and then pulverized to obtain a powdery epoxy resin composition.

Next, using the powdered epoxy resin composition obtained as described above, each of
Samples were prepared by DIP transfer molding under the conditions of pressure 70 kg / cm ² , temperature 175 ° C., time 2 minutes. In this case, the model element of is a piezoresistive element, the model element of is a moisture resistance evaluation Al wiring model element, and the model element of is a passivation crack evaluation element. Then, the stress applied to the semiconductor element after molding was determined from the piezoresistance change rate using the above-obtained sample, and shown in Table 1 above. Also, using the above sample, apply a bias voltage of 20 V between the Al patterns and
The average lifespan (MTTF) obtained as a result of performing a Precure Kucker bias test (hereinafter abbreviated as “PCBT”) at 30 ° C./85% RH is shown in Table 1 above. In addition, using the above sample, thermal cycle test (TCT) [−65 ℃ × 5min−150
℃ × 5 min] for 400 cycles and the number of cracks generated on the passivation film of the model device was counted. The obtained results are shown in Table 1.

As is clear from Table 1, the example product is superior not only in the low stress property but also in the moisture resistance reliability as compared with the comparative example product.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideto Suzuki Hide 1-2, Shimohozumi, Ibaraki City Nitto Denki Kogyo Co., Ltd. (56) References JP 62-519 (JP, A)

Claims (1)

(57) [Claims] 1. The following (A) to (D) as essential components,
A semiconductor device in which a semiconductor element is sealed with an epoxy resin composition containing (E) as an arbitrary component. (A) Epoxy resin. (B) a phenolic resin. (C) tetra-substituted phosphonium / tetra-substituted borate,
At least one boron compound selected from the group consisting of tetra-substituted ammonium / tetra-substituted borate, tetra-substituted arsonium / tetra-substituted borate and tetra-substituted borate of imidazole compound. (D) Sb ₂ O ₅ · 4H ₂ O. (E) Organopolysiloxane.