JPS63245949A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve moisture resistance and low stress property by sealing a semiconductor element with epoxy resin composition which contains specific boron compound, Sb2O2.4H2, and arbitrarily organosiloxane. CONSTITUTION:Epoxy resin composition contains epoxy resin, phenol resin, specific boron compound and Sb2O5.4H2O as indispensable ingredients, and organosiloxane as arbitrary ingredient. A semiconductor element is sealed with the composition, and the sealing resin has excellent moisture resistance reliability. Further, use of the sealing resin which contains organopolysiloxane as an arbitrary ingredient provides low stress property in addition to the moisture resistance to reduce stress applied to the element itself. Thus, the element of super LSI can be sufficiently sealed to obtain a semiconductor device having high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor device that has excellent reliability, particularly moisture resistance reliability, and has low stress applied to semiconductor elements.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are usually sealed with ceramic packages, plastic packages, or the like to form semiconductor devices. The above-mentioned ceramic package has heat resistance in the constituent material itself,
It also has excellent moisture permeability, so it is resistant to temperature and humidity, and because it is a hollow package, it has high mechanical strength and can be sealed with high reliability. However, since the constituent materials are relatively expensive and the mass productivity is poor, resin sealing using the above-mentioned plastic package has recently become mainstream. Epoxy resin compositions have conventionally been used for this type of resin sealing, and have achieved good results. However, due to technological innovation in the semiconductor field, the degree of integration has increased, element sizes have become larger, and interconnects have become finer, and packages are also becoming smaller and thinner. There is a demand for further improvement in reliability (internal stress, moisture resistance reliability, shock resistance reliability, heat resistance reliability, etc. of the resulting semiconductor device).

[Problem that the invention seeks to solve]

In other words, the epoxy resin composition used for semiconductor encapsulation generates considerable internal stress due to shrinkage during the cooling process from the curing temperature to room temperature, and this internal stress can cause cracks in the passivation film of the semiconductor element, clutter or clutter in the semiconductor element itself. Problems have arisen, such as deterioration of characteristics and, in some cases, cracks occurring in the sealing resin itself.

In order to solve these problems, conventional methods have been to reduce the stress of the sealing resin made of the cured epoxy resin composition by blending organopolysiloxane or synthetic rubber particles into the epoxy resin composition. We are trying to make this happen.

However, in this case, although the stress applied to the element is reduced, there are drawbacks such as deterioration of the moisture resistance of the semiconductor device due to the influence of ionic impurities and parent wood groups contained in the organopolysiloxane and synthetic rubber themselves. is occurring.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a semiconductor device that has excellent moisture resistance and reliability, and in which less stress is applied to the semiconductor element itself.

[Means for solving problems]

In order to achieve the above object, the semiconductor device of the present invention includes:
The structure is such that a semiconductor element is sealed using an epoxy resin composition containing the following (A) to (D) as essential components and (E) as an optional component.

(A) Epoxy resin.

(B) Phenol resin.

, (C) tetra-substituted phosphonium/tetra-substituted borate, tetra-substituted ammonium/tetra-substituted borate, tetra-substituted arsonium/tetra-substituted borate, and tetra-substituted borate of imidazole compound (both of which are one type of boron compound).

(D)SbzOs・4H10゜ (E) Organopolysiloxane.

That is, the present inventors first conducted research on an epoxy resin composition system that does not contain organopolysiloxane, with the aim of improving the moisture resistance of a sealing resin made of a cured product of the above-mentioned epoxy resin composition. As a result, in order to improve moisture resistance, it is necessary to combine the special boron compound of the above component (C) with the component (D).
It has been found that the combined use of the ingredients 5bzOs.4 and 20 is effective. As a result of further research, it was found that when these are blended into conventional epoxy resin compositions aimed at reducing stress, a sealing resin with not only low stress properties but also excellent moisture resistance can be obtained. I found out what happened. Particularly when organopolysiloxane is used as the stress-lowering component, such stress-lowering effects and moisture resistance improvement effects become remarkable.

The semiconductor device of this invention has an epoxy resin (component A), a phenol resin (component B), a special boron compound (component C), and 5bzOs 4HtO (component D) as essential components, and an organopolysiloxane (component E). Optional ingredients.

The epoxy resin of component A is not particularly limited, and various epoxy resins conventionally used as sealing resins for semiconductor devices, such as Talesol novolac type, phenol novolac type, and bisphenol A type, can be used. Among these resins, good results can be obtained by using one that has a melting point above room temperature and exhibits a solid state or a highly viscous solution state at room temperature.The most typical novolac type epoxy resins are In addition to Talesol novolac type epoxy resins, alkylated phenol novolac type epoxy resins in which various alkyl groups such as tertiary butyl groups and methyl groups are added to the phenol moiety are generally used. As these novolac type epoxy resins, those having an epoxy equivalent of 160 to 300 and a softening point of 50 to 130°C are used.

The phenol resin of component B used together with the above epoxy resin (component A) acts as a curing agent for the above epoxy resin, and is used to convert phenol novolac, talesol novolak, and other alkyl groups such as methyl groups and tertiary butyl groups into phenol. An alkylated phenol novolac resin added to the phenol is preferably used. As these novolak resins, those having a softening point of 50 to 110°C and a hydroxyl equivalent of 70 to 180 are preferably used.

The mutual usage ratio of the above-mentioned epoxy resin (component A) and phenol resin is appropriately selected depending on the relationship between epoxy equivalent and hydroxyl group equivalent, but the equivalent ratio of phenolic hydroxyl group to epoxy group is in the range of 0.5 to 1.5. is desirable. This is because if it is outside this range, it will be difficult to obtain a sufficient reaction.

The special boron compounds as component C used together with the epoxy resin as component A and the phenol resin as component B include tetra-substituted phosphonium/tetra-substituted borate, tetra-substituted ammonium/tetra-substituted borate, tetra-substituted arsonium/tetra-substituted borate, various imidazole compounds (
These compounds include tetra-substituted borates (including derivatives of imidazole compounds). These may be used alone or in combination.

Examples of the above-mentioned tetra-substituted phosphonium/tetra-substituted borate include tetrabutylphosphonium/tetraphenylborate, n-butyltriphenylphosphonium/tetraphenylborate, tetraphenylphosphonium/tetraphenylborate, trimethylphenylphosphonium/tetraphenylborate, diethylmethylphenylphosphonium/tetraphenylborate, Tetraphenylborate, diallylmethylphenylphosphonium tetraphenylborate, (2-hydroxylethyl)triphenylphosphonium tetraphenylborate, ethyltriphenylphosphonium tetraphenylborate, p-xylene bis(triphenylphosphonium tetraphenylborate) , tetraphenylphosphonium tetraethylborate, tetraphenylphosphonium triethylphenylborate, tetraphenylphosphonium tetrabutylborate, and the like. In addition, as tetra-substituted arsonium/tetra-substituted borate, tetramethylarsonium/tetraphenylborate, tetraphenylarsonium/
Examples include tetraphenylborate, dimethyldiethylarsonium tetraphenylborate, triethyl-n-octylarsonium tetraphenylborate, and the like.

Examples of the tetra-substituted ammonium/tetra-substituted borate include triethylamine/tetraphenylborate, trimethylamine/tetraphenylborate, triphenylamine/tetraphenylborate, diethylmethylamine/tetraethylborate, diphenylmethylamine/tetraphenylborate, and the like. Furthermore, as tetra-substituted borates of imidazole compounds and derivatives thereof, imidazole tetraphenylborate, 2
-Ethyl-4-methylimidazole tetraphenylborate, 1-cyanoethyl-2-ethyl-4-methylimidazole tetraphenylborate, 1-cyanoethyl-2-undecylimidazole tetraphenylborate, 1-cyanoethyl-2-phenyl Imidazole・
Examples include tetraphenylborate, 2-undecylimidazole/tetraphenylborate, 2-heptadecylimidazole/tetraphenylborate, 1-ethyl-2-ethylimidazole/yumedraphenylborate, and the like.

The general formula for these is as follows.

Tetra-substituted phosphonium/tetra-substituted borate.

Tetra-substituted arsonium/tetra-substituted borate.

Tetra-substituted ammonium/tetra-substituted borate @ Tetra-substituted borate of imidazole compounds.

The boron compound of component (C), which is a substituted phenyl group, is used as an anion trapping agent, but also functions as a curing accelerator. In addition, it is also possible to use a conventionally known curing accelerator together with the above-mentioned C component. The blending amount of such component (C) is the same as the epoxy resin composition of component (A) and (B).
It is set at about 0.1 to 4% by weight (hereinafter abbreviated as "%") of the total amount of the component phenolic resin. It is preferably within the range of 0.5 to 3%. If the amount of component (C) is less than 0.1%, the ion trapping effect will be insufficient, and if it exceeds 4%, there will be a tendency for the storage stability of the epoxy resin composition to deteriorate. .

Component (D) 5bzOs.4H20 is a component that effectively traps cations such as sodium ions present in the epoxy resin composition. As this component (D), for example, AHK-600 manufactured by Toagosei (Tarusha Co., Ltd.) is commercially available. It is preferable to set the amount in the range of 0.1 to 20% of the total amount of component (D), and more preferably in the range of 0.3 to 10%.If the amount of component (D) used is less than 0.1%, the ion This is because the trapping effect becomes insufficient, and conversely, if it exceeds 20%, other properties other than moisture resistance tend to be adversely affected.

Also, (E) used together with the above components (A) to (B)
The organopolysiloxane component is an optional component and is used as necessary. Such an organopolysiloxane exhibits the effect of reducing the internal stress of the sealing resin as described above, and it is preferable to use one represented by the following general formula (1). In particular, it is preferable to use a random copolymer as the organopolysiloxane. However, the above general formula (1
) and other organopolysiloxanes may be used together without any problem. Further, instead of the organopolysiloxane represented by the above general formula (1), a liquid polydimethylsiloxane in which both ends of the molecular chain have a methyl group, a carboxyl group, an amino group, an epoxy group, etc. may be used. . The amount of the organopolysiloxane blended is preferably set to 1 to 50% of the total amount of the components (A) and (B).

Most preferred is 5-30%. In other words, if the amount of organopolysiloxane is less than the above range, a sufficient stress reduction effect will not be obtained, whereas if it exceeds the above range, a decrease in resin strength will be observed. .

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

As the mold release agent, conventionally known long-chain carboxylic acids such as stearic acid and palmitic acid, metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate, and waxes such as carnauba wax and montan wax may be used. Can be done.

Further, the inorganic filler is not particularly limited, and commonly used quartz glass powder, talc, silica powder, alumina powder, etc. can be used as appropriate.

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

Tertiary amine triethanolamine, tetramethylhexanediamine, triethylenediamine, dimethylaniline, dimethylaminoethanol, diethylaminoethanol, 2.4
．． 6-(dimethylaminomethyl)phenol, N, N'
-dimethylpiperazine, pyridine, picoline,! , 8-
Diaza-bicyclo(5,4,0)undecene-7, benzyldimethylamine, 2-(dimethylamino)methylphenol quaternary ammonium salt dodecyltrimethylammonium iodide, cetyltrimethylammonium chloride, benzyldimethyltetradecylammonium chloride, stearyltrimethyl Ammonium chloride imidazoles 2-methylimidazole, 2-undecylimidazole, 2-ethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole boron compounds tetraphenylboron, tetraphenylborate, N-
Methylmorpholine tetraphenylborate Note that compounds other than those mentioned above can also be used as long as they are generally used as curing accelerators for epoxy resins and phenolic resins.

The epoxy resin composition used in this invention can be produced, for example, as follows. That is, the epoxy resin as the component (A), the phenol resin as the component (B), and the epoxy resin as the component (C).
) component boron compound and component (D) 5bzos.
4H20, and if necessary, the organopolysiloxane of component (E), a curing accelerator, a mold release agent, a filler, and other additives are blended according to a conventional method, and then put into a kneading machine such as a mixing roll machine. Multiply. Then, it can be manufactured by a series of steps of melt-mixing this in a heated state and, if necessary, tableting.

The encapsulation of a 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 semiconductor device obtained in this way has extremely excellent moisture resistance, and especially when using organopolysiloxane as component (E), it exhibits excellent low stress properties as well as the moisture resistance. I come to do it.

〔Effect of the invention〕

As described above, the semiconductor device of the present invention comprises a special boron compound as the component (C) and sb, oS as the component (D).
- It is sealed using a special epoxy resin composition containing auto, and the sealing resin has excellent moisture resistance, so it has excellent moisture resistance reliability. Furthermore, when a cured epoxy resin composition containing organopolysiloxane as an optional component is used as a sealing resin, it has excellent low stress properties in addition to the above-mentioned moisture resistance.
The stress applied to the semiconductor element itself becomes extremely small. Therefore, by sealing with the above-mentioned special epoxy resin composition, it is possible to sufficiently cope with the sealing of semiconductor elements such as ultra-LSIs and ultra-super LSIs, and it becomes possible to obtain semiconductor devices with extremely high reliability.

Next, examples will be described together with comparative examples.

[Examples 1-6, Comparative Examples 1-6] 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 inorganic fillers, meltable SiO□ is 70% of the total, 5b20 is 2% of the total, carbon is 0.3% of the total, and carnauba wax is 0% of the total.
．． 5% was added. Next, this blend was kneaded for 5 minutes with a heated roll at 120°C, cooled, and then ground to obtain a powdered epoxy resin composition.

(Leaving space below) Zero 8: (◎) 4P's ・Be (◎) 4 Middle 10: (◎) sC mountain PΦ ・Be (◎) 4 Ne 11: 2-Methylimidazole *12: 1. 8-Diaza-bicyclo(5,4,0
) Undecene-7 Next, using the powdered epoxy resin composition obtained as described above, model elements of ■ to ■ were placed in 16 bottles DIP, pressure cuff 0 kg/cj, temperature 175°C for 1 hour 2.
Samples ■～■ were made by transfer molding under the conditions of 10 minutes. In this case, the model element (■) is a piezoresistance element, the model element (2) is an AJ wiring model element for evaluating moisture resistance, and the model element (2) is an element for evaluating passivation cracks. Using the thus obtained sample (2) above, the stress applied to the semiconductor element after molding was determined from the rate of change in piezoresistance and is shown in Table 1 above. In addition, the mean life (MTTF) obtained as a result of applying a bias voltage of 20 V between the Al patterns and performing a pressure puller bias test (hereinafter abbreviated as rPCBTJ) at 130°C/85% RH using the sample in (2) above. are shown in Table 1 above. In addition, thermal cycle test (TCT) (-65℃ x 5m1n 150℃
x 5 wheels in) for 400 cycles, and the number of cracks generated in the passivation film of the model element was counted. The results obtained are shown in Table 1.

As is clear from Table 1, compared to the comparative height measurements, the actual height measurements are not only superior in low stress properties but also superior in moisture resistance and reliability.

Claims (1)

[Claims] (1) A semiconductor device in which a semiconductor element is sealed using an epoxy resin composition containing the following (A) to (D) as essential components and (E) as an optional component. (A) Epoxy resin. (B) Phenol resin. (C) tetra-substituted phosphonium tetra-substituted borate,
At least one boron compound selected from the group consisting of tetra-substituted ammonium/tetra-substituted borates, tetra-substituted arsonium/tetra-substituted borates, and tetra-substituted borates of imidazole compounds. (D) Sb_2O_5・4H_2O. (E) Organopolysiloxane.