JPH0841176A - Sealing epoxy resin composition and semiconductor device sealed therewith - Google Patents

Abstract

PURPOSE:To obtain a sealing epoxy resin composition excellent in humidity resistance, high-temperature electrical properties, etc., by mixing an epoxy resin with a phenol aralkyl resin, a novolac phenolic resin and an organophosphine compound. CONSTITUTION:This composition essentially consists of an epoxy resin (e.g. bisphenol A epoxy resin), a phenol aralkyl resin represented by the formula (wherein n is 1 or greater), a novolac phenolic resin (e.g. phenol novolac resin) and an organophosphine compound. Examples of the organophosphine compounds used as cure accelerators include triphenylphosphine and tributylphosphine. This composition may optionally contain an inorganic filler (e.g. crystalline silica powder), a mold release (e.g. natural wax), a flame retardant (e.g. antimony trioxide), etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing epoxy resin composition and a resin-sealed semiconductor device using the same.

[0002]

2. Description of the Related Art A resin-encapsulated semiconductor device, for example, protects semiconductor elements such as integrated circuits (ICs), large-scale integrated circuits (LSIs), transistors, and diodes from the external atmosphere and mechanical shock. It is formed by sealing with a thermosetting resin.

Conventionally, as a sealing technique for semiconductor elements, hermetic sealing using metal, ceramics or the like has been adopted, but recently, resin sealing has become the mainstream because it is economically advantageous. ing.

As such a resin for semiconductor encapsulation, an epoxy resin composition for low-pressure molding, which can be used in a low-pressure transfer molding method suitable for mass production, is generally widely used. However, the conventional resin-encapsulated semiconductor device obtained by transfer molding an epoxy resin composition including, for example, an epoxy resin, a novolac-type phenol resin curing agent, and an imidazole oxidation accelerator has the following drawbacks. . That is, (1) corrosion and deterioration of aluminum electrodes and the like due to poor moisture resistance, (2) poor electrical characteristics at high temperatures, and particularly, a decrease in the function of the semiconductor element due to an increase in leak current; It is. Explaining (1) among these, since the resin-encapsulated semiconductor device may be used or stored in a high temperature and high humidity atmosphere,
Reliability must be guaranteed even under such conditions. As a reliability evaluation test for quality assurance of moisture resistance, an accelerated evaluation method of exposing to saturated steam at 85 ° C or 120 ° C is performed. Recently, a bias application type evaluation test in which a voltage is applied to further enhance the accelerating property has been carried out.

However, in a resin-sealed semiconductor device using an epoxy resin composition, since the sealing resin has a hygroscopic property, moisture is transferred from an external atmosphere via the sealing resin layer or between the sealing resin and the lead frame. Penetrates through the interface of the semiconductor device and reaches the surface of the semiconductor element. As a result of the action of the moisture and impurities present in the sealing resin, the resin-sealed semiconductor device causes a defect due to corrosion of the aluminum electrodes, wirings and the like. Further, when a bias voltage is applied, defects due to corrosion of aluminum electrodes and wirings occur particularly frequently due to the electrochemical action.

Next, regarding (2), since the resin-encapsulated semiconductor device may be used under high temperature conditions,
Even under such conditions, reliability must be guaranteed. As an evaluation test therefor, an accelerated test in which a bias voltage is applied at 80 ° C. to 150 ° C. to evaluate reliability is generally used.

In such a test, for example, as a particularly frequently occurring defect in a device having a MOS structure whose semiconductor surface is sensitive to external charges, a device having a PN junction to which a reverse bias is applied, etc. There is an increasing phenomenon. It is considered that this phenomenon occurs due to the electric field acting on the sealing resin layer in contact with the surface of the element to which the voltage is applied.

The conventional resin-encapsulated semiconductor device has the above-mentioned drawbacks, and therefore has been required to be improved.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to remedy such disadvantages of the conventional resin-encapsulated semiconductor device, and to provide a highly reliable sealing device having excellent moisture resistance and high-temperature electrical characteristics. An object of the present invention is to provide an epoxy resin composition for stopping and a resin-sealed semiconductor device using the same.

[0010]

As a result of intensive studies by the present inventors in order to achieve the above object, the following epoxy resin composition was used as a conventional resin for sealing semiconductor devices. It has been found that it has excellent characteristics as compared with a resin composition, and further that by using this, a resin-encapsulated semiconductor device excellent in moisture resistance and high-temperature electrical characteristics can be obtained.

That is, the present invention is a resin composition for encapsulation comprising (a) an epoxy resin, (b) a phenol aralkyl resin, (c) a novolac type phenol resin, and (d) an organic phosphine compound.

The present invention also provides a resin-encapsulated semiconductor device obtained by encapsulating a semiconductor device with a cured product of an epoxy resin composition, wherein the epoxy resin composition comprises (a) epoxy resin (b) phenol aralkyl resin ( A resin-encapsulated semiconductor device comprising: c) a novolac-type phenol resin and (d) an organic phosphine compound.

The epoxy resin used in the present invention is generally known and is not particularly limited. For example, glycidyl ether type epoxy resin such as bisphenol A type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, An epoxy resin having two or more epoxy groups in one molecule, such as a heterocyclic epoxy resin and a halogenated epoxy resin, may be used. These epoxy resins may be used alone or in a mixture of two or more.

The more preferred epoxy resin used in the present invention is a novolak epoxy resin having an epoxy equivalent of 170 to 300, such as a phenol novolak epoxy resin, a cresol novolap epoxy resin, a halogenated phenol novolak epoxy resin, and the like. It is. These epoxy resins preferably have a chlorine ion content of 10 ppm or less and a hydrolyzable chlorine content of 0.1% by weight or less. The reason for this is that if more than 10 ppm of chlorine ions or more than 0.1% by weight of hydrolyzed chlorine are contained, the aluminum electrode of the sealed semiconductor element is likely to be corroded.

The phenol aralkyl resin used as a curing agent for the epoxy resin in the present invention is represented by the general formula [I]
Can be shown as

[0016]

Embedded image Here, n is an integer of 1 or more. The phenol aralkyl resin can be generally obtained by condensing phenol and α, α′-dimethoxyparaxylene by a Friedel-Crafts reaction. In addition, since it is marketed under the trade name of Xyloc, it can be easily obtained. In the above formula [I], a preferable value of n or a preferable average value of n is n = 2 to 20.

The mixing ratio of the epoxy resin to the phenol aralkyl resin is preferably such that the number of phenolic hydroxyl groups of the phenol aralkyl resin is 0.5 to 1.5 per one epoxy group of the epoxy resin. . If the ratio is out of the above range, the characteristic tends to deteriorate.

In the present invention, examples of the novolac type phenol resin used together with the phenol aralkyl resin as a curing agent for the epoxy resin include phenol novolac resin, cresol novolac resin, tert-butylphenol novolac resin, nonylphenol novolac resin, and the like. For example, phenol,
Cresol, xylenol, hydroquinone, resorcin, catechol, bisphenol A, bisphenol F
It can be obtained by condensing phenols such as aldehydes with aldehydes. The softening point of such a novolac type phenol resin is preferably in the range of 60 to 120 ° C., and the water-soluble phenol resin component at room temperature is preferably 3% or less.

Regarding the compounding ratio of the novolac type phenol resin, the total of the phenolic hydroxyl groups of the phenol aralkyl resin and the novolac type phenol resin should be 0.5 to 1.5 with respect to the number of epoxy groups of the epoxy resin. It is preferable to mix them. If the ratio is out of the above range, the characteristic tends to deteriorate. Also, the compounding ratio of phenol aralkyl resin and novolac type phenol resin is
It is desirable that the novolak-type phenol resin is blended in an amount of 0.01 to 100 parts by weight per 1 part by weight of the phenol aralkyl resin. This is because if the amount is less than 0.01 part by weight, the effect of adding the novolac type phenol resin is difficult to recognize, and if the amount is 100 parts by weight or more, the effect of the phenol aralkyl resin is diminished. In order to effectively mix the phenol aralkyl resin and the novolac type phenol resin, a melted mixture of both may be prepared in advance and used.

The phenol aralkyl resin and the novolac type phenol resin may be used in combination with other curing agents. Examples of such other curing agents include phenol compounds having two or more phenolic hydroxyl groups in one molecule, acid anhydrides and amine compounds, and the like.
What is known as a curing agent for epoxy resin can be used. Among these, a phenol compound having two or more phenolic hydroxyl groups in one molecule is preferable.

Examples of the phenol compound having two or more phenolic hydroxyl groups in one molecule include a resol type phenol resin, polyhydroxystyrene, tris (hydroxyphenyl) methane, tetrakis (hydroxyphenyl) ethane, bisphenol A, bisphenol F and the like. Is mentioned.

On the other hand, in the present invention, by using the organic phosphine compound as the curing accelerator, the moisture resistance of the resin-encapsulated semiconductor device can be improved as compared with the case where the conventional curing accelerators such as imidazole and amine are used. The high temperature electrical properties can be significantly improved.

The organic phosphine compound used in the present invention has the formula [II]:

[0024]

Embedded image A third phosphine compound wherein R _{1 to} R ₃ are all organic groups, a second phosphine compound wherein only R ₃ is hydrogen,
There is a first phosphine compound in which both R ₂ and R ₃ are hydrogen. Specific examples include triphenylphosphine, tributylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, butylphenylphosphine, diphenylphosphine, phenylphosphine, octylphosphine, and the like. Further, R ₁ may be an organic group containing an organic phosphine. For example, 1,2-bis (diphenylphosphino) ethane, bis (diphenylphosphino)
Such as methane. Of these, arylphosphines are preferable, and triarylphosphines such as triphenylphosphine are particularly preferable. These organic phosphine compounds may be used alone or in a mixture of two or more.

The amount of the organic phosphine compound to be added is generally 0.03% of the resin component (epoxy resin and curing agent).
A range of from 0.01 to 20% by weight, but particularly preferred properties are obtained in a range of from 0.01 to 5% by weight. By setting the amount of the organic phosphine compound in this range, an epoxy resin composition for sealing having excellent properties can be obtained. When the amount is less than 0.001% by weight, the effect of the addition is hardly recognized, and there is a disadvantage that the curing of the epoxy resin composition requires a long time, and when it exceeds 20% by weight, the quality is adversely affected.

The epoxy resin composition according to the present invention may optionally contain an inorganic filler.
In particular, in the case of transfer molding semiconductor elements such as integrated circuits and transistors, it is preferable to incorporate an inorganic filler. One of the reasons is to improve the moldability. Another is to reduce the difference in the coefficient of thermal expansion between the sealing resin such as elements, bonding wires, lead frames, etc. This is to reduce defects that occur due to a large difference in thermal expansion coefficient such as breakage.

As the inorganic filler used in the present invention, quartz glass powder, crystalline silica powder, glass fiber, talc, alumina powder, calcium silicate powder,
Among them are calcium carbonate powder, barium sulfate powder, magnesium powder and the like. Among them, quartz glass powder and crystalline silica powder are most preferable in terms of high purity and low thermal expansion coefficient. The amount of the inorganic filler varies depending on the type of the epoxy resin, the curing agent and the inorganic filler. For example, when used in transfer molding, the weight ratio is 1.5 times the total amount of the epoxy resin and the curing agent. It may be about 4 times. Regarding the particle size distribution of the inorganic filler, the formability can be improved by combining coarse particles and fine particles to make the distribution uniform.

The epoxy resin composition according to the present invention may be used, if necessary, for example, with a release agent such as natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters or paraffins, chlorination. A flame retardant such as paraffin, bromotoluene, hexabromobenzene, antimony trioxide, a coloring agent such as carbon black, a silane coupling agent, etc. may be appropriately added and blended in an amount of about 0.01 to 10% by weight.

As a general method for preparing the epoxy resin composition according to the present invention as a molding material, a raw material composition selected in a predetermined composition ratio is sufficiently mixed by, for example, a mixer, and then melt-mixed by a hot roll. An epoxy resin molding material can be easily obtained by adding a treatment or a mixing treatment using a kneader or the like.

The resin-encapsulated semiconductor device of the present invention can be easily manufactured by encapsulating the semiconductor device using the epoxy resin composition or the molding material. The most common method of sealing is the low-pressure transfer molding method, but sealing by injection molding, compression molding, casting, etc. is also possible. As a special encapsulation method, a method of coating the semiconductor surface with a solvent-type or non-solvent-type composition, or a localized encapsulation as a so-called junction coating can be used. It can also be used as a resin composition for die bonding.

The epoxy resin composition or the molding material is heated and cured at the time of encapsulation, and finally a resin-encapsulated semiconductor device encapsulated by the cured product of the composition or the molding material can be obtained. it can. It is desirable to heat to 150 ° C. or higher upon curing.

The semiconductor device in the present invention is an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode and the like, and is not particularly limited.

[0033]

Next, synthesis examples of the present invention will be described. Synthesis Example 1 A phenol aralkyl resin having a hydroxyl equivalent of 174 and a phenol novolac resin having a hydroxyl equivalent of 104 were mixed in an amount of 100 parts by weight and heated at 160 ° C. to make them compatible with each other to obtain a molten mixture. This was cooled and pulverized to obtain a raw material for the epoxy resin composition.

Next, an embodiment of the present invention will be described. Examples 1 to 4 Cresol novolac type epoxy resin having an epoxy equivalent of 220 (epoxy resin A), brominated epoxy novolac resin having an epoxy equivalent of 290 (epoxy resin B), phenol novolac type epoxy resin having an epoxy equivalent of 200 (epoxy resin C), Phenol aralkyl resin having a hydroxyl equivalent of 174 and a hydroxyl equivalent of 104 as phenol compound A
Phenol novolac resin, cresol novolac resin having a molecular weight of 800 as phenol compound B, hydroquinone novolac resin (hydroxyl group equivalent 70) as phenol compound C, melt mixture of Synthesis Example 1, triphenylphosphine, 2-methylimidazole, dimethylaminomethylphenol, Tetraphenylphosphonium / tetraphenylborate, quartz glass powder, antimony trioxide, carbax, carbon black, silane coupling agent (γ-glycidoxypropyltrimethoxysilane) were selected for the composition (parts by weight) shown in Table 1, By mixing each composition with a mixer and kneading with a heating roll, 14 types of transfer molding materials including comparative examples were prepared.

[0035]

[Table 1] The MOS integrated circuit was resin-sealed by transfer molding using the molding material thus obtained. Sealing is performed by molding the molding material heated to 90 ° C with a high frequency
Molding was performed at 2 ° C. for 2 minutes, and after-curing was performed at 200 ° C. for 8 hours. The following test was conducted for each of the 100 resin-sealed semiconductor devices. (1) A humidity resistance test (bias PCT) was conducted by applying 10 V in water vapor at 120 ° C. and 2 atm to check for disconnection defects due to corrosion of aluminum wiring. The results are shown in Table 2. (2) Offset gate MOS in an oven at 100 ° C
A drain voltage of 5 V and an offset gate voltage of 5 V are applied to the FET circuit to perform a test (MOS-BT test) for checking a leak current defect due to deterioration of electrical characteristics. When the leak current increases 100 times or more of the initial value, it is defective. The results are shown in Table 3.

[0036]

[Table 2]

[0037]

[Table 3] Example 5 A compound represented by the following formula (epoxy resin D) as an epoxy resin,

[0038]

Embedded image (However, n = 2, epoxy equivalent 160) The same raw materials as in Examples 1 to 4 are used except that a novolac type phenol resin (phenol compound D, hydroxyl equivalent 120) obtained by the condensation reaction of bisphenol A and an aldehyde is used as the phenol compound. Shown in Table 4 (parts by weight)
Was prepared.

[0039]

[Table 4] Using these compositions, an evaluation test of a resin-encapsulated semiconductor device was performed in the same manner as in Examples 1 to 4. The results are shown in Tables 5 and 6.

[0040]

[Table 5]

[0041]

[Table 6]

[0042]

As is apparent from the above-mentioned objects, outlines and examples of the present invention, a resin-sealed semiconductor device obtained by encapsulating a semiconductor using the epoxy resin composition of the present invention has a bias. The PCT is excellent in moisture resistance as shown by extremely low corrosion breakage of the aluminum wiring due to moisture in the PCT, and is excellent in high-temperature electrical characteristics in the MOS-BT test as shown by extremely low leakage current. Therefore, according to the present invention, a highly reliable resin-sealed semiconductor device can be obtained.

Claims (2)

[Claims] 1. An epoxy resin composition for sealing, comprising (a) an epoxy resin, (b) a phenol aralkyl resin, (c) a novolak type phenol resin, and (d) an organic phosphine compound. 2. A resin-encapsulated semiconductor device in which a semiconductor device is encapsulated with a cured product of an epoxy resin composition, wherein the epoxy resin composition comprises: (a) an epoxy resin; (b) a phenol aralkyl resin; A resin-encapsulated semiconductor device comprising a novolak-type phenol resin and (d) an organic phosphine compound.