JPH0319706B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly reliable resin-encapsulated semiconductor device sealed with a cured product of an epoxy resin composition. Epoxy resin has excellent electrical properties, mechanical properties, chemical resistance, etc., and is therefore widely used as a highly reliable electrical insulating material for encapsulating semiconductor devices.
Recently, most semiconductor devices, such as integrated circuits, large-scale integrated circuits, transistors, diodes, etc., have been encapsulated using epoxy resin compositions for low-pressure molding, instead of conventional hermetic encapsulation using ceramics. As an epoxy resin composition for semiconductor encapsulation,
Epoxy resin compositions comprising an epoxy resin, a novolac-type phenolic resin curing agent, and an imidazole curing accelerator are widely used in consideration of reliability, moldability, and the like. However, using conventional epoxy resin sealing resin,
Resin-sealed semiconductor devices obtained by transfer molding have the following drawbacks. (1) Moisture resistance is inferior to the high level of reliability required for resin-encapsulated semiconductor devices. (2) High temperature resistance is inferior to the high level of reliability required for resin-encapsulated semiconductor devices. Regarding the moisture resistance mentioned above, resin-sealed semiconductor devices are sometimes used or stored in high-temperature, high-humidity environments, so reliability must be guaranteed even under such conditions. . Evaluation tests for moisture resistance quality assurance include 85°C or 120°C.
An accelerated evaluation method has been conducted in which the material is exposed to saturated water vapor, and recently, a bias application type evaluation test in which a voltage is applied to further improve acceleration has also been conducted. However, the cured product of the encapsulated epoxy resin composition is hygroscopic and moisture permeable, so under such high temperature and high humidity conditions, moisture from the outside can penetrate into the interior through the cured epoxy resin layer, or It enters 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 impurity ions existing in the sealing resin, resin-sealed semiconductor devices exhibit defects mainly due to decreased insulation, increased leakage current, and corrosion of aluminum electrodes, wiring, etc. occurs. Further, when a bias voltage is applied, defects due to corrosion of aluminum electrodes and wiring occur particularly frequently due to its electrochemical action. Conventional resin-sealed semiconductor devices are not fully satisfied with the above-mentioned moisture resistance, and there has been a demand for improved moisture resistance. Next, electric characteristics at high temperatures will be explained. Since resin-sealed semiconductor devices are sometimes used under high temperature conditions, reliability must be guaranteed even under such conditions. A typical evaluation test for this purpose is an accelerated test in which reliability is evaluated by applying a bias voltage at 80°C to 150°C. In such tests, defects that occur particularly frequently in devices with MOS structures with sensitive surfaces or devices with PN junctions to which reverse bias is applied are as follows:
It is well known that there is a phenomenon in which leakage current increases due to channeling. This phenomenon is thought to occur when an electric field acts on the resin layer that is in contact with the surface of the element to which a voltage is applied. Conventional resin-sealed semiconductor devices are not fully satisfactory with respect to the above-mentioned electrical characteristics at high temperatures, and improvements have been sought. The purpose of the present invention is to improve the drawbacks of conventional resin-sealed semiconductor devices, and to provide a highly reliable resin-sealed semiconductor device that is encapsulated with an epoxy resin composition that has excellent moisture resistance and high-temperature electrical properties. An object of the present invention is to provide a static semiconductor device. In order to achieve the above object, the present inventors have conducted extensive research and have found that curing accelerators and the like are the main factors contributing to the above-mentioned difficulties, and furthermore, the present inventors have found that curing accelerators and the like are the main factors contributing to the above-mentioned difficulties, and furthermore, they have found that curing accelerators, etc. It has been discovered that a cured product made from It has been discovered that a resin-sealed semiconductor device with excellent characteristics and reliability can be obtained. That is, the present invention provides a resin-encapsulated semiconductor device in which a semiconductor device is sealed with a cured product of an epoxy resin composition, wherein the cured product comprises (a) a novolac type epoxy resin having an epoxy equivalent of 170 to 300; (b) Novolac-type phenolic resin with a softening point of 60°C to 120°C, (c) Chemical formula [1] , M is selected from phosphorus, arsenic, antimony, bismuth, X is selected from oxygen, sulfur, selenium, R ₁ is selected from organic groups, R ₂ ,
R ₃ is a resin-sealed semiconductor device characterized by containing at least one compound selected from an organic group or hydrogen, and (d) an inorganic filler. The epoxy resin which is the first component constituting the cured product according to the present invention is a novolak type epoxy resin having an epoxy equivalent of 170 to 300, such as a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a halogenated Examples include phenol novolac type epoxy resin. These epoxy resins may be used alone or in a mixed system of two or more. Further, 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. Examples of the novolak-type phenolic resin curing agent, which is the second component constituting the cured product according to the present invention, include phenol novolak resin, cresol novolak resin, test-butylphenol novolak resin,
Examples include nonylphenol novolak resin. The softening point of these phenolic resins is 60℃ ~
Must be within 120℃. The reason is
This is because if the temperature is lower than 60°C or higher than 120°C, the effects of the present invention cannot be sufficiently obtained. Further, it is preferable that the phenol resin component soluble in water at room temperature is 3% or less. These curing agents can be used alone or in a mixed system of two or more. Regarding the compounding ratio of epoxy resin and curing agent, the ratio of the number of phenolic hydroxyl groups in the novolak type phenolic resin to the number of epoxy groups in the epoxy resin is 0.5.
It is desirable that it be within the range of ~1.5. The reason for this is that if it is less than 0.5 or more than 1.5, the reaction will be sufficiently difficult to occur and the properties of the cured product will deteriorate. The curing accelerator, which is the third component constituting the cured product according to the present invention, has the chemical formula [1] , M is selected from phosphorus, arsenic, antimony, and bismuth, X is selected from oxygen, sulfur, and selenium, R ₁ is selected from organic groups, and R ₂ and R ₃ are selected from organic groups or hydrogen. at least one of the compounds
It is a seed. Examples of the organic group include an alkyl group, an aryl group, a cycloalkyl group, an alkaryl group, and an aralkyl group. Specific examples of the compound of chemical formula [1] include triphenylphosphine oxide, triphenylphosphine sulfide, triphenylphosphine selenide, trimethylphosphine oxide, triethylphosphine sulfide, tris(chloromethyl)phosphine oxide, and triphenylphosphine oxide. Dihexylphosphine, phenylphosphine oxide, dimenylmethylphosphine sulfide, trimethylarsine oxide, triethylarsine sulfide, triphenylarsine oxide, triphenylarsine sulfide, trimethylstibine oxide, trimethylstibine sulfide, triphenylstibine sulfide , methyl bismuth oxide, etc. The blending amount is preferably within the range of 0.01 to 20% by weight based on the resin components (epoxy resin and phenolic resin). Examples of the inorganic filler, which is the fourth component constituting the cured product according to the present invention, include quartz glass powder, crystalline silica powder, glass fiber, talc, alumina powder, calcium silicate powder, calcium carbonate powder, and barium sulfate powder. , magnesia powder, etc., but among these, 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, phenolic resin curing agent, and inorganic filler, but for example, when used in transfer molding, the total amount of epoxy resin and phenolic resin curing agent by weight ratio
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 can be used as necessary, for example, natural waxes, synthetic waxes,
Mold release agents such as metal salts of straight chain fatty acids, acid amides, esters or paraffins, chlorinated paraffins, bromotoluene, hexabromobenzene,
Flame retardants such as antimony trioxide, colorants such as carbon black, silane coupling agents, etc. may be appropriately added and blended. 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 using, for example, a mixer, and then melt-mix using hot rolls. An epoxy resin molding material can be easily obtained by processing or mixing 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 injection molding,
Sealing by compression molding, casting, etc. is also possible. The epoxy resin composition or molding material is heated and cured at the time of sealing, and a resin-sealed semiconductor device can finally be obtained which is encapsulated with the cured product of this composition or molding material. can. When curing
Heating to 150°C or higher is particularly desirable. The semiconductor device referred to 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. Next, embodiments of the present invention will be described. Examples 1 to 4 Cresol novolac type epoxy resin with epoxy equivalent weight 220 (epoxy resin A), epoxy equivalent weight 290
Brominated epoxy novolac resin (epoxy resin B), phenol novolac resin curing agent with a softening point of 80°C, triphenylphosphine sulfide, trephenylarsine oxide, trimethylstibine oxide, triphenylphosphine selenide, 2- Heptadecylimidazole, carnauba wax, quartz glass powder, antimony trioxide, carbon black, and silane coupling agent (γ-glycidoxypropyltrimethoxysilane) were selected in the composition ratios (parts by weight) shown in Table 1, and each A transfer molding material was prepared by mixing the composition with a mixer and kneading with a heated roll. The 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 195℃ for 10 minutes, and then heated to 180℃ for 10 minutes.
This was done by after-curing at ℃ for 10 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 to check for disconnection defects due to corrosion of the aluminum wiring by applying 10V, and the results are shown in Table 2. (2) Offset gate in oven at 100℃
A test (NOS-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.If the leakage current increases to more than 100 times the initial value, it is determined to be defective. The results are shown in Table 3.

【table】

【table】

[Table] Incidentally, each component in the cured product of the epoxy resin composition according to the present invention can be analyzed as follows. That is, for the novolak type epoxy resin which is the first component and the novolak type phenol resin which is the second component, infrared spectrophotometry (pyrolysis method), pyrolysis gas chromatography-mass spectrometry method, and nuclear magnetic resonance method are used. It can be analyzed by etc. Regarding the compound of chemical formula [1], which is the third component, the cured product was finely pulverized and extracted with a solvent, and was analyzed by infrared spectrophotometry, gas chromatography-mass spectrometry, nuclear magnetic resonance, etc. can be analyzed. On the other hand, the fourth component, the inorganic filler, can be confirmed by chemical analysis after oxidizing and removing the organic components in the cured product. Cured products of six types of epoxy resin compositions that encapsulated semiconductor devices using these methods (Analysis Examples 1 to 3)
The results of analysis 6) are shown in Table 4. Of these six types of analysis examples, analysis examples 1 to 4
is a cured product having the compositional components of the present invention, while Analysis Examples 5 and 6 are results in which conventional sealing resins were analyzed in the same manner. These results are shown in Table 4 below.

[Table] ○: Contains ×: Does not contain In addition, for the semiconductor devices sealed with the compositions of these analysis examples 1 to 6, the compositions of the previous examples 1 to 4
And the same humidity test (bias) as in Comparative Examples 1 and 2.
PCT) and electrical characteristics test (MOS-BT test) are shown in Tables 5 and 6 below, respectively.
Shown in the table.

【table】

[Table] As described above, it was confirmed that the resin-sealed semiconductor device according to the present invention has excellent moisture resistance and electrical properties.

Claims (1)

[Scope of Claims] 1. A resin-encapsulated semiconductor device in which a semiconductor device is encapsulated with a cured product of an epoxy resin composition, wherein the cured product is (a) a novolak type having an epoxy equivalent of 170 to 300; Epoxy resin, (b) Novolac type phenolic resin with a softening point of 60℃ to 120℃, (c) Chemical formula [1] , M is selected from phosphorus, arsenic, antimony, bismuth, X is selected from oxygen, sulfur, selenium, R ₁ is selected from organic groups, R ₂ ,
A resin-encapsulated semiconductor device characterized in that R ₃ contains at least one compound selected from an organic group or hydrogen, and (d) an inorganic filler.