JPH0379370B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field to which the invention pertains] The present invention relates to an epoxy resin composition for sealing and a resin-encapsulated semiconductor device using the same. [Technical background of the invention and its problems] Resin-sealed semiconductor devices are, for example, integrated circuits (ICs), large-scale integrated circuits (LSIs), transistors,
In order to protect semiconductor elements such as diodes from external atmosphere and mechanical shock, they are sealed using thermosetting resin. Conventionally, hermetic sealing using metals, ceramics, etc. has been employed as a sealing technique for semiconductor elements, but recently resin sealing has become mainstream because it is economically advantageous. As such semiconductor encapsulating resins, low-pressure molding epoxy resin compositions that can be used in low-pressure transfer molding methods suitable for mass production are generally widely used. However, conventional resin-encapsulated semiconductor devices obtained by transfer molding an epoxy resin composition consisting of an epoxy resin, a novolac-type phenolic resin curing agent, an imidazole oxidation promoter, etc. have the following drawbacks. be. That is, (1) aluminum electrodes etc. deteriorate due to corrosion due to poor moisture resistance; (2) electrical properties at high temperatures are poor, and in particular, leakage current increases, resulting in a decline in the functionality of semiconductor elements; It is. Regarding (1) among these, resin-sealed semiconductor devices are sometimes used or stored in high-temperature, high-humidity environments, so reliability must be guaranteed even under such conditions. As a reliability evaluation test for quality assurance of moisture resistance, an accelerated evaluation method in which the product is exposed to saturated steam at 85°C or 120°C is used. Recently, bias application type evaluation tests have also been conducted in which a voltage is applied to further improve acceleration. However, in a resin-encapsulated semiconductor device using an epoxy resin composition, since the encapsulating resin has hygroscopic properties, moisture can be absorbed from the external atmosphere through the encapsulating resin layer.
Alternatively, it penetrates into the interior through the interface between the sealing resin and the lead frame and reaches the surface of the semiconductor element. As a result of the action of this moisture and impurities present in the sealing resin, resin-sealed semiconductor devices develop defects due to corrosion of aluminum electrodes, wiring, etc. Furthermore, when a bias voltage is applied, defects due to corrosion of aluminum electrodes and wiring occur particularly frequently due to its electrochemical action. Next, regarding (2), since resin-sealed semiconductor devices are sometimes used under high-temperature conditions, reliability must be guaranteed even under such conditions. The evaluation test for this purpose is 80℃~
Accelerated tests that evaluate reliability by applying a bias voltage at 150°C are common. In such tests, for example, a phenomenon in which leakage current increases due to channeling occurs, which occurs particularly frequently in devices with a MOS structure where the semiconductor surface is sensitive to external charges, or devices with a PN junction to which a reverse bias is applied. There is. This phenomenon is thought to be caused by an electric field acting on the sealing resin layer that is in contact with the surface of the element to which voltage is applied. Since conventional resin-sealed semiconductor devices have the above-mentioned drawbacks, improvements have been sought. [Object of the Invention] The object of the present invention is to improve the drawbacks of conventional resin-encapsulated semiconductor devices, and to provide a highly reliable encapsulating epoxy that has excellent moisture resistance and high-temperature electrical properties. An object of the present invention is to provide a resin composition and a resin-sealed semiconductor device using the same. [Summary of the Invention] As a result of extensive research by the present inventors to achieve the above object, the following epoxy resin composition has been found to be superior to conventional epoxy resin compositions as a sealing resin for semiconductor devices. Furthermore, they have found that by using the same, a resin-sealed semiconductor device with excellent moisture resistance and high-temperature electrical properties can be obtained. That is, the present invention is a sealing resin composition characterized by containing (a) an epoxy resin, (b) a phenol aralkyl resin, and (c) an organic phosphine compound. The present invention also provides a resin-encapsulated semiconductor device in which a semiconductor device is sealed with an epoxy resin composition, wherein the epoxy resin composition comprises (a) an epoxy resin, (b) a phenol aralkyl resin, and (c) an organic phosphine compound. A resin-sealed semiconductor device characterized by comprising: The epoxy resin used in the present invention is commonly known and is not particularly limited. For example, bisphenol A type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, linear aliphatic epoxy resin, alicyclic type Examples include epoxy resins having two or more epoxy groups in one molecule, such as epoxy resins, heterocyclic epoxy resins, and halogenated epoxy resins. However, these epoxy resins are 1
It may be used as a species or as a mixture of two or more types. More preferred epoxy resins used in the present invention are novolak type epoxy resins having an epoxy equivalent of 170 to 300, such as phenol novolak type epoxy resins, cresol novolak type epoxy resins, and halogenated phenol novolak type epoxy resins. be. These epoxy resins desirably have a chlorine ion content of 10 ppm or less and a hydrolyzable chlorine content of 0.1% by weight or less. The reason is that if more than 10 ppm of chlorine ions or more than 0.1% by weight of hydrolyzed chlorine is contained,
This is because the aluminum electrodes of the sealed semiconductor element are likely to be corroded. The phenol aralkyl resin used as a curing agent for epoxy resin in the present invention can be represented by the general formula [ ]. However, n is an integer of 1 or more. The above phenolic aralkyl resin is generally composed of phenol and α,
It can be obtained by condensing α'-dimethoxyparaxylene with Friedel-Crafts reaction. It is also easily available as it is commercially available under the trade name Zairoku. In the above formula [ ], a preferable value of n or a preferable average value of n is n=2 to 20. Regarding the blending ratio of the epoxy resin and the phenol aralkyl resin, it is desirable that the number of phenolic hydroxyl groups in the phenol aralkyl resin is 0.5 to 15 per 1 epoxy group in the epoxy resin. This is because outside the above range, characteristics tend to deteriorate. This phenol aralkyl resin may be used alone as a curing agent for epoxy resins, but it can also be used in combination with other curing agents. As such other curing agents, those known as curing agents for epoxy resins, such as phenol compounds having two or more phenolic hydroxyl groups in one molecule, acid anhydrides, and amine compounds, can be used. Among these, phenol compounds having two or more phenolic hydroxyl groups in one molecule are preferred. Phenol compounds having two or more phenolic hydroxyl groups in one molecule include those obtained by condensing phenols such as phenol, cresol, xylenol, hydroquinone, resorcinol, catechol, bisphenol A, and bisphenol F with aldehydes. Novolak type phenolic resin, resol type phenolic resin, polyhydroxystyrene, tris(hydroxyphenyl)methane, tetrakis(hydroxyphenyl)ethane,
Bisphenol A, bisphenol A, bisphenol F and the like can be mentioned. Regarding the blending ratio of the phenol compound, it is preferable to blend the phenol aralkyl resin and the phenolic compound so that the total number of phenolic hydroxyl groups of the phenol aralkyl resin and the phenol compound is 0.5 to 1.5 to 1 of the epoxy groups of the epoxy resin. This is because outside the above range, characteristics are likely to deteriorate. In addition, the blending ratio of phenol aralkyl resin and phenol compound is
It is desirable that the phenol compound be blended in a range of 0.01 to 100 parts by weight per 1 part by weight of the phenol aralkyl resin. This is because if it is less than 0.01, the effect of the addition of the phenol compound is difficult to recognize, and if it is more than 100 parts by weight, the effect of the phenol aralkyl resin is diminished. In order to effectively mix the phenolic aralkyl resin and the phenolic compound, a molten mixture of the two may be prepared in advance and used. On the other hand, in the present invention, by using an organic phosphine compound as a curing accelerator, the moisture resistance and high temperature properties of resin-sealed semiconductor devices are improved compared to the case where conventional curing accelerators such as imidazole and amines are used. Electrical properties can be significantly improved. The organic phosphine compound used in the present invention has the formula []: There are a tertiary phosphine compound in which R ₁ to _{R 3} are all organic groups, a second phosphine compound in which only R ₃ is hydrogen, and a first phosphine compound in which R ₂ and R ₃ are both hydrogen. Specifically, they include triphenylphosphine, tributylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, butylphenylphosphine, diphenylphosphine, phenylphosphine, octylphosphine, and the like. Further, R ₁ may be an organic group containing an organic phosphine. Examples include 1,2-bis(diphenylphosphino)ethane and bis(diphenylphosphino)methane. Among these, arylphosphines are preferred, and triarylphosphines such as triphenylphosphine are particularly preferred. Further, these organic phosphine compounds may be used alone or in a mixed system of two or more. However, the amount of the organic phosphine compound used in the lever is generally determined based on the resin components (epoxy resin and curing agent).
It may be within the range of 0.001 to 20% by weight, but particularly preferred properties are obtained within the range of 0.01 to 5% by weight. By particularly setting the blending amount of the organic phosphine compound within this range, an epoxy resin composition for sealing with excellent properties can be obtained. Compounding amount is 0.001% by weight
If it is less than 20% by weight, the effect of the addition is difficult to recognize, and the epoxy resin composition has the disadvantage of requiring a long time to cure, and if it exceeds 20% by weight, it will have a negative effect on quality. An inorganic filler can be added to the epoxy resin composition according to the present invention if necessary, but in particular, in the case of transfer molding of semiconductor elements such as integrated circuits and transistors, an inorganic filler is not necessary. It is preferable to mix them. This is partly to improve moldability, and another reason is to reduce the difference in thermal expansion coefficient between the parts to be sealed, such as elements, bonding wires, and lead frames, and the sealing resin. This is to reduce defects that occur due to large differences in thermal expansion coefficients, such as cuts. Inorganic fillers used in the present invention include quartz glass powder, crystalline silica powder, glass fiber, talc, alumina powder, calcium silicate powder, calcium carbonate powder, barium sulfate powder, magnesia powder, etc. Among them, quartz glass powder and crystalline silica powder are most preferred in terms of high purity and low coefficient of thermal expansion. However, the blending amount of these inorganic fillers varies depending on the type of epoxy resin, curing agent, and inorganic filler, but for example, when used in transfer molding, the proportion by weight to the total amount of epoxy resin and curing agent is in
It may be about 1.5 times to 4 times. Regarding the particle size distribution of the inorganic filler, moldability can be improved by making the distribution uniform by combining coarse particles and fine particles. The epoxy resin composition according to the present invention may be used, as necessary, with release agents such as natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters, or paraffins, chlorinated paraffin, bromine, etc. Toluene, hexambromobenzene,
A flame retardant such as antimony trioxide, a coloring agent such as carbon black, a silane coupling agent, etc. may be appropriately added in an amount of about 0.01 to 10% by weight. A general method for preparing the epoxy resin composition according to the present invention as a molding material is to thoroughly mix the raw material components selected at a predetermined composition ratio, for example, using a mixer, and then melt-mix them using hot rolls. Alternatively, an epoxy resin molding material can be easily obtained by adding a mixing treatment using a kneader or the like. The resin-sealed semiconductor device of the present invention can be easily manufactured by sealing the semiconductor device using the epoxy resin composition or molding material. The most common method for sealing is low-pressure transfer molding, but sealing by injection molding, compression molding, casting, etc. is also possible. As a special sealing method, a method of coating a semiconductor surface using a solvent type or non-solvent type composition, and a method of local sealing as so-called juncture coating can also be used.
It can also be used as a resin composition for die bonding. The epoxy resin composition or molding material is heated and cured during sealing, and finally a resin-sealed semiconductor device can be obtained which is sealed with the cured product of this composition or molding material. . During curing, it is desirable to heat to 150°C or higher. The semiconductor device in the present invention includes an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode, etc., and is not particularly limited. [Examples of the Invention] Next, synthesis examples of the present invention will be described. Synthesis Example 1 Phenolaralkyl resin with hydroxyl equivalent of 174,
Each phenol novolac resin with a hydroxyl equivalent of 104
100 parts by weight were mixed and heated to 160°C to make them compatible, to obtain a molten mixture. This was cooled and pulverized to be used as a raw material for an epoxy resin composition. Next, embodiments of the present invention will be described. Examples 1 to 5 Cresol novolac type epoxy resin with epoxy equivalent weight 220 (epoxy resin A), epoxy equivalent weight 290
Brominated perepoxy novolak resin (epoxy resin B), phenol aralkyl resin with a hydroxyl equivalent of 174, phenol novolak resin with a hydroxyl equivalent of 104 as phenol compound A, molten mixture of Synthesis Example 1, triphenylphosphine, 2-methylimidazole , dimethylaminomethylphenol, quartz glass powder, antimony trioxide, carnauba wax, carbon black, silane coupling agent (γ-glycidoxypropyltrimethoxysilane)
The compositions (parts by weight) shown in Table 1 were selected, and each composition was mixed using a mixer and kneaded using heated rolls to prepare 10 types of transfer molding materials, including comparative examples.

[Table] A MOS type integrated circuit was resin-sealed by transfer molding using the molding material thus obtained. For sealing, the molding material was heated to 90℃ using a high-frequency preheater, then molded at 175℃ for 2 minutes, and then heated to 200℃.
This was done by after-curing at ℃ for 8 hours.
The following tests were conducted on 100 of each of the above resin-sealed semiconductor devices. (1) A moisture resistance test (bias PCT) was conducted in water vapor at 120°C and 2 atm, applying 10V to check for breakage due to corrosion of the aluminum wiring, and the results are shown in Table 2. (2) Offset gate in oven at 100℃
A test (MOS-BT test) is performed to check for leakage current defects due to deterioration of electrical characteristics by applying a drain voltage of 5V and an offset gate voltage of 5V to the MOSFET circuit, and if the leakage current increases to more than 100 times the initial value, It was judged as defective and the results are shown in Table 3.

【table】

【table】

[Table] Examples 6 to 8 Compounds represented by the following formula as epoxy resins (epoxy resin C), (However, n = 2, epoxy equivalent: 160) Novolac type phenol resin (phenol compound B, hydroxyl equivalent: 120), tris(hydroxyphenyl)methane (phenol compound C, hydroxyl equivalent: 120) produced by condensation reaction of bisphenol A and aldehyde as phenol compounds Compositions having the compositions (parts by weight) shown in Table 4 were formed using the same raw materials as in Examples 1 to 5, except that polyhydroxystyrene (phenol compound D, hydroxyl equivalent: 120) was used.

【table】

[Table] Using these compositions, evaluation tests for resin-sealed semiconductor devices were conducted in the same manner as in Examples 1 to 5. The results are shown in Tables 5 and 6.

【table】

[Table] [Effects of the Invention] As is clear from the purpose of the present invention, the description of the outline, and the examples, there is a resin-sealed semiconductor device in which a semiconductor is encapsulated using the epoxy resin composition of the present invention. MOS-BT has excellent moisture resistance, as shown by the extremely low corrosion disconnection of aluminum wiring due to moisture in bias PCT, and MOS-BT
In tests, it has excellent high-temperature electrical properties, as shown by extremely low leakage current. Therefore, according to the present invention, a highly reliable resin-sealed semiconductor device can be obtained.

Claims (1)

[Scope of Claims] 1. An epoxy resin composition for sealing, comprising (a) an epoxy resin, (b) a phenol aralkyl resin, and (c) an organic phosphine compound. 2. In a resin-encapsulated semiconductor device formed by encapsulating a semiconductor device with an epoxy resin composition, the epoxy resin composition contains (a) an epoxy resin, (b) a phenolaralkyl resin, and (c) an organic phosphine compound. A resin-sealed semiconductor device characterized by: