JPH0549696B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a resin-encapsulated semiconductor device using an epoxy resin composition, and more specifically to a highly reliable resin using an epoxy resin composition with excellent moisture resistance and high-temperature electrical properties. The present invention relates to a sealed semiconductor device. [Technical background of the invention and its problems] In recent years, epoxy resin compositions have been used not only as adhesives and paint resins because of their excellent mechanical properties and electrical properties near room temperature. It is also widely used as an electrical insulating material. However, on the other hand, the performance required of electrical insulating materials made of such epoxy resin compositions has become more sophisticated year by year, making it difficult to satisfy the demands with conventional materials. I'm getting used to it. In particular, there is a problem in that when the temperature of electrically insulating materials and the like rises, the electrical properties thereof deteriorate significantly, and improvements are desired. Conventionally, epoxy resins include tertiary amines, imidazole, boron trifluoride monoethylamine complexes,
A method of curing by adding a boron trifluoride triethylamine complex, a boron trifluoride piperidine complex, or the like as a curing catalyst is well known. However, the epoxy resin composition cured by such a method has a drawback in that its electrical properties, particularly at high temperatures, are insufficient. In addition, since such epoxy resin compositions have high hygroscopicity,
When used as an electrical insulating material, etc., it has the disadvantage of causing defects due to corrosion. Conventionally, hermetic sealing using metals, ceramics, etc. has been used as a sealing technology to protect semiconductor elements such as integrated circuits (ICs), large-scale integrated circuits (LSIs), transistors, and diodes from the external atmosphere and mechanical shock. However, recently, due to its economic advantages, resin,
In particular, sealing with thermosetting resin is the mainstream. 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 hardener, an imidazole hardening accelerator, etc. have the following drawbacks. be. That is, (1) aluminum electrodes etc. deteriorate due to corrosion due to low moisture resistance; (2) electrical properties are poor at high temperatures, and in particular, leakage current increases, resulting in a decline in the functionality of semiconductor elements. , is. Regarding (1) among these, resin-sealed semiconductor devices are sometimes used or stored in a high temperature and high humidity atmosphere, so quality must be guaranteed even under such conditions. As a reliability evaluation test for quality assurance of moisture resistance,
Accelerated evaluation tests have been conducted in which the material is exposed to saturated steam at 85°C or 120°C, but recently, bias application type evaluation tests have also been conducted in which voltage is applied to further increase 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. Further, when a bias voltage is applied, defects due to corrosion of aluminum electrodes and wiring become particularly severe due to its electrochemical action. Next, regarding (2), since resin-sealed semiconductor devices are sometimes used under high-temperature conditions, quality must be guaranteed even under such conditions. The evaluation test for this purpose is 80℃~150℃.
Accelerated tests that evaluate reliability by applying a bias voltage at ℃ 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. Therefore, there has been a strong desire in the industry to develop highly reliable resin-sealed semiconductor devices with excellent moisture resistance and high-temperature electrical properties. [Object of the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks, that is, to provide a highly reliable resin-sealed semiconductor device with excellent moisture resistance and high-temperature electrical characteristics. [Summary of the Invention] The resin-sealed semiconductor device of the present invention is a resin-sealed semiconductor device in which a semiconductor device is sealed with an epoxy resin composition, in which the epoxy resin composition contains (a) an epoxy resin (b) ) At least one compound selected from the group consisting of epoxy resins having at least two phenolic hydroxyl groups in one molecule and acid anhydrides as a curing agent (c) An organic phosphine compound and (d) a carboxyl group as a curing accelerator. It is characterized by containing an organosilicon compound having the following. 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. In addition, these epoxy resins may be one or two types.
It may be used in a mixed system of more than one species. 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, halogenated phenol novolak type epoxy resins, etc. can be mentioned. The content of chlorine ions in these epoxy resins is preferably 10 ppm or less, and the content of hydrolyzable chlorine is preferably 0.1% by weight or less.
This is because if this content is out of the above range, defects due to corrosion are likely to occur. The epoxy resin curing agent and/or acid anhydride used as a curing agent in the present invention consists of the following. The curing agent used in the present invention may be any epoxy resin curing agent having two or more phenolic hydroxyl groups in one molecule.
Preference is given to using phenolic resins, polyoxystyrenes or polyhydric phenolic compounds. Specific examples include phenolic resins such as phenol novolac resin, cresol novolac resin, tert-butylphenol novolac resin, nonylphenol novolac resin, novolac type phenolic resin, and cresol type phenolic resin; Oxystyrene; and bisphenol A
and substituted halogen compounds thereof, and one or more compounds selected from the group consisting of these may be used. Among these, novolak type phenolic resin and polyoxystyrene are more preferred. Next, the acid anhydride used as a curing agent is
Any aliphatic, alicyclic or aromatic carboxylic anhydride or substituted carboxylic anhydride thereof may be used. Examples of such acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, nadic anhydride (3,6-endomethylene -1,2,3,6-tetrahydrophthalic anhydride), methylnadic anhydride, 3,3',4,4'-
1 selected from the group consisting of benzophenonetetracarboxylic anhydride, tetrabromophthalic anhydride, chlorendic anhydride, etc.
A species or two or more species may be used. It is desirable to select the amount of the curing agent appropriately from the relationship with the epoxy group weight of the epoxy resin.
The equivalent ratio of the phenolic hydroxyl group and/or acid anhydride group to the epoxy group is preferably within the range of 0.5 to 1.5. When the equivalent ratio is out of the above range, the moisture resistance of the resulting epoxy resin composition tends to decrease. The curing accelerator used in the present invention is an organic phosphine compound, and by incorporating such a compound, the moisture resistance and high-temperature electrical properties of the resin-sealed semiconductor device are improved. Such organic phosphine compounds have the following general formula [] [In the formula, R ₁ , R ₂ and R ₃ may be the same or different and are represented by a hydrogen atom, an alkyl group, an aryl group such as a phenyl group, a tolyl group, a cycloalkyl group such as a cyclohexyl group, etc. represents a group.
Also expression (In the formula, R represents an alkane, R' and
R″ may be the same or different, and R″ may be a hydrogen atom,
It represents an alkyl group, an aryl group such as a phenyl group or a tolyl group, or a cycloalkyl group such as a cyclohexyl group. However _, this excludes the case where R _′ and R _″ are hydrogen atoms.) An organic group containing an organic phosphine, such as the group shown by Except in certain cases.] For example, tertiary phosphine compounds such as triphenylphosphine, tributylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, butylphenylphosphine, diphenylphosphine, etc. Secondary phosphine compounds such as Yin, primary phosphine compounds such as phenylphosphine and octylphosphine, and tertiary bisphosphine compounds such as bis(diphenylphosphine)methane and 1,2-bis(diphenylphosphine)ethane. One or more compounds selected from the group consisting of these compounds are used.Among these, it is preferable to use arylphosphine compounds, and especially triarylphosphine compounds such as triphenylphosphine. Phosphine is the most preferred. The amount of the organic phosphine compound is usually 0.001 to 20% based on the total amount of the epoxy resin and curing agent.
% by weight, preferably 0.01 to 10% by weight. This is because if the amount is less than 0.001% by weight, no effect of the addition will be observed, and if it exceeds 20% by weight, the electrical properties of the epoxy resin composition will deteriorate. The organosilicon compound used in the present invention may be any organosilicon compound having at least one carboxyl group in one molecule, and it is preferable to use a silane compound or a siloxane compound. Specific examples of this silane compound include 2-trimethylsilylacetic acid, 2-triphenylsilylacetic acid, 3-trimethylsilylpropionic acid, and 3-triphenylsilylpropionic acid, and 1 selected from the group consisting of these.
A species or two or more species may be used. Also,
The siloxane compound has both terminal groups selected from organic groups, organosilicon groups, hydrogen, silane, etc. (although they may be the same or different), and the main chain structural units are of the following formula: (In the formula, R ₁ to _{R 4} may be the same or different and each represents an alkyl group having 1 to 35 carbon atoms or an aryl group having 6 to 35 carbon atoms, and m is 0 or 1 or more. Integers, l and n each represent an integer of 1 or more. The amount of the organosilicon compound blended is usually 0.001 to 20% by weight, preferably 0.01 to 10% by weight, based on the total amount of the epoxy resin and curing agent. The reason for this is that if the amount is less than 0.001% by weight, no effect of addition will be observed, and if it exceeds 20% by weight, the moisture resistance of the epoxy resin composition will decrease. In the epoxy resin composition of the present invention, a reaction mixture obtained by heating and melt-mixing an organosilicon compound having a carboxyl group and an epoxy resin may be used. At this time, an organic phosphine compound may be added and blended as a curing accelerator. The epoxy resin composition used in the present invention may contain an inorganic filler and various additives in addition to the above-mentioned components. Examples of the inorganic filler include quartz glass powder, crystalline silica powder, glass fiber, talc, alumina powder, calcium silicate powder, calcium carbonate powder, barium sulfate powder, magnesia powder, etc., and a group consisting of these. One or more selected types are used. Among these, it is preferable to use quartz glass powder and crystalline silica powder because they have high purity and a low coefficient of thermal expansion. The blending amount of such an inorganic filler needs to be appropriately selected depending on the type of epoxy resin, curing agent, and inorganic filler used. For example, when used for transfer molding, the amount of the epoxy resin and curing agent The weight ratio is preferably about 1.5 to 4 times the total amount. Further, the particle size of the inorganic filler may be appropriately selected and used, and moldability can be improved by mixing a combination of coarse particles and fine particles. In addition, various additives include, for example, natural waxes, synthetic waxes, metal salts of straight chain fatty acids,
Mold release agents such as acid amides, esters, paraffins, flame release agents such as chlorinated paraffin, bromotoluene, hexabromobenzene, antimony trioxide,
Coloring agents such as carbon black, silane coupling agents, etc. may be included, and these may be appropriately added and blended depending on the purpose. In order to prepare the epoxy resin composition having the above composition as a molding material, a normal method may be used. For example, after mixing the raw ingredients in a predetermined amount with a mixer etc., A molding material made of an epoxy resin composition can be easily obtained by melt-mixing using a kneader or the like. The resin-sealed semiconductor device of the present invention can be manufactured by encapsulating semiconductor devices such as ICs, LSIs, transistors, thyristors, and diodes using a molding material made of the epoxy resin composition. . Such a sealing method may be a commonly employed method, such as a low-pressure transfer molding method, an injection molding method, a compression molding method, a casting method, etc. Among them, it is preferable to use a low-pressure transfer molding method. is preferred. Furthermore, it is also possible to use a special sealing method in which the semiconductor surface is coated with a solvent-based or non-solvent-based composition, or a local sealing method as so-called juncture coating. In addition, when curing the sealing resin, it is preferable to cure it at a temperature of 150° C. or higher. In the following, the present invention will be explained in more detail with reference to Examples. [Embodiments of the invention] Production example: 1000 parts of cresol novolak type epoxy resin (epoxy resin A) with an epoxy equivalent of 220 and 30 parts of methylpolysiloxane with a carboxyl equivalent of 3500 are mixed and heated to 150°C under a nitrogen atmosphere to melt. Mixed. After 2 hours, it was taken out and cooled to obtain a reaction mixture. Examples 1 to 3 A cresol novolac type epoxy resin (epoxy resin A) having an epoxy equivalent of 220 and a brominated epoxy novolac resin (epoxy resin B) having an epoxy equivalent of 290 are used as the epoxy resin, and a molecular weight of 800 as the curing agent. Using a phenol novolac resin, using triphenylphosphine as an organic phosphine compound, using 2-triphenylsilylacetic acid and methylpolysiloxane with a carboxyl equivalent of 3500 as an organic silicon compound, and using the reaction mixture obtained in the production example, In addition, quartz glass powder (inorganic filler), antimony trioxide (flame retardant), carnauba wax (mold release agent), carbon black (coloring agent), and γ-glycidoxypropyltrimethoxysilane (silane coupling agent) ), epoxy resin compositions (Examples 1 to 3) were prepared with the formulations (parts by weight) shown in Table 1. At the same time, as comparative examples, those without using an organic phosphine compound or an organic silicon compound, or those using an imidazole compound (2-methylimidazole) as a curing accelerator (Comparative Examples 1 to 3) were prepared, respectively. Such an epoxy resin composition was ground into fine particles, mixed, and kneaded using heated rolls to obtain a uniform molding composition. The following tests were conducted to examine the moisture resistance and high temperature electrical properties of this composition. This composition was transfer molded at 170° C. for 2 minutes to obtain a disk with a thickness of 2 mm. Add this disk to 180 more
After curing at ℃ for 3 hours, it was used as a sample for measurement.
When the volume resistivity of the above samples was measured at 150°C, Examples 1 to 3 were approximately 3×10 ¹⁴ Ωcm, Comparative Example 1 was 1/3 of that, and Comparative Examples 2 and 3 were 1/3 of that. It was /50, 1/100. Next, the above sample was placed in water vapor at 120℃ and 2 atmospheres for 50 minutes.
When the volume resistivity of Examples 1 to 3 was measured at room temperature immediately after being left for a period of time, it was approximately 1×10 ¹⁵ Ω・cm, and that of Comparative Examples 1, 2, and 3 was 1/3, 1/100, and 1, respectively. /
It was 200.

【table】

[Table] Using the above molding composition, transfer molding was performed to resin-seal a MOS type integrated circuit. For sealing, the molding material is heated to 90℃ using a high-frequency preheater.
This was done by molding at 175°C for 2 minutes and then after-curing at 180°C for 3 hours. According to the above method, 100 resin-sealed semiconductor devices were manufactured using each epoxy resin composition, and the following tests were conducted. (1) Moisture resistance test (bias PCT): 10V was applied in water vapor at 120°C and 2 atm, and the cumulative failure rate (%) of defective products in which aluminum wiring broke due to corrosion was investigated over time. (2) MOS-BT test: Apply a drain voltage of 5V and an offset gate voltage of 5V to the offset gate MOS FET circuit in an oven at 100℃, and when the leakage current value increases to more than 100 times the initial value. were considered to be defective, and the cumulative defective rate (%) of defective products that occurred was investigated over time. Table 2 shows the results of the moisture resistance test, and Table 3 shows the results of the MOS-BT test to investigate high-temperature electrical characteristics.

【table】

〔Effect of the invention〕

As described in detail above, the resin-sealed semiconductor device of the present invention has excellent moisture resistance and high-temperature electrical properties, and is much more reliable than conventional devices, and has great industrial value.

Claims (1)

[Scope of Claims] 1. A resin-encapsulated semiconductor device formed by encapsulating a semiconductor device with an epoxy resin composition, wherein the epoxy resin composition contains (a) an epoxy resin, and (b) at least one curing agent in one molecule. At least one compound selected from the group consisting of an epoxy resin curing agent having two phenolic hydroxyl groups and an acid anhydride; (c) containing an organophosphine compound as a curing accelerator; and (d) an organosilicon compound having a carboxyl group. A resin-sealed semiconductor device characterized by: 2. The resin-sealed semiconductor device according to claim 1, wherein the epoxy resin is a novolak type epoxy resin having an epoxy equivalent of 170 to 300. 3. The resin-sealed semiconductor device according to claim 1, wherein the epoxy resin curing agent is a novolac type phenolic resin. 4. The resin-sealed semiconductor device according to claim 1, wherein the organosilicon compound is a polysiloxane compound having a carboxyl group and/or a silane compound having a carboxyl group. 5. The resin-sealed semiconductor device according to claim 1, which uses a reaction mixture of an epoxy resin and an organosilicon compound.