JPH078939B2 - Resin-sealed semiconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin-encapsulated semiconductor device encapsulated with a resin-encapsulating material.

(Prior Art) It is no exaggeration to say that semiconductor devices play a leading role in supporting the recent industrial development. Also, therefore, users desire semiconductor devices with higher performance, lower cost, and higher reliability. However, in order to meet such demands, it is necessary to establish various technologies, and one of them is the semiconductor chip sealing technology that enables protection of the semiconductor chip in the environment in which the semiconductor device is used. is there.

Here, as a conventional sealing technique, a technique of putting a semiconductor chip in a package made of metal or ceramics and sealing various base resins such as epoxy resin, a curing material, and a filler (filler). ), A technique of molding a semiconductor chip with an encapsulating material containing a curing accelerator, a flame retardant, a coupling agent, a release agent, a coloring agent, and the like.

Of these, encapsulation using a package of ceramics or the like has been mainly used for a semiconductor device which is required to have high reliability because it is excellent in mechanical strength and moisture resistance. However, the package itself is expensive, and the process of sealing the semiconductor chip has not been easy. On the other hand, the encapsulating material mainly composed of resin has the advantages that it can be priced down and has high mass productivity, and is widely used in the manufacture of general-purpose semiconductor devices, but there are still points to be improved. was there.

One of the points that needs to be improved is the improvement of the moisture resistance of the cured product of the sealing material. That is, if the cured product of the encapsulating material used for molding the semiconductor chip has poor moisture resistance, the insulating property of the semiconductor device is deteriorated, leak current is increased, and even moisture is absorbed in the semiconductor chip. This is because the aluminum wiring of the semiconductor chip is corroded or broken when the temperature reaches. Also, although the volume of the semiconductor chip tends to increase with the expansion of the functions of the semiconductor device, in the situation where the outer shape of the semiconductor device is limited, the resin thickness cannot help but be thin. Even considering this situation, the moisture resistance of the cured product of the sealing material becomes very important. Further, as a technical trend in recent years, surface mounting is desired, and in this case, the semiconductor device is exposed to the heat of solder flow for a long time. In such a case, if the semiconductor device takes in water, the semiconductor device will be broken due to cracks or the like. Also in this respect, it is preferable that the cured product of the sealing material has high moisture resistance.

Therefore, various attempts have heretofore been made in order to improve the reliability of the sealing material. (For example, Nikkei New Material [25] (1987) “Changing IC encapsulant”).

As one example, there has been research focused on improving the purity of the base resin. The reason for this is that it is known that water that has entered the semiconductor device corrodes aluminum wiring in the presence of ionic impurities, and this is to prevent this. At present, it is possible to provide a resin having a hydrolyzable chlorine content of 100 ppm or less.

In addition, the stress generated in the semiconductor device causes cracks in the cured product of the encapsulating material, resulting in a decrease in the moisture resistance of the semiconductor device. In order to reduce the stress of the cured material of the encapsulating material, the moisture resistance of the semiconductor device has been secondarily improved.

(Problems to be Solved by the Invention) However, it cannot be said that any of the conventional encapsulating materials positively improve the water absorbency and moisture permeability, and the cured product thereof basically has water absorbency and moisture permeability. There was a problem of having. Therefore, if a semiconductor device using a conventional encapsulating material is exposed to a high temperature and high humidity atmosphere, moisture (moisture) permeates from the outside to the semiconductor chip, which lowers insulation and increases leakage current. Further, there is a problem that the electrode wiring is corroded or broken.

In addition, since the encapsulating material having a low content of hydrolyzable chlorine itself is very expensive, the cost of a product (semiconductor device or the like) using the encapsulating material is increased, which is not preferable.

The present invention has been made in view of the above points, and an object of the present invention is to provide a highly reliable resin-sealed semiconductor device having low water absorption and moisture permeability.

(Means for Solving the Problem) In order to achieve this object, according to the present invention, in a resin-sealed semiconductor device in which a part of a lead portion and a semiconductor chip are sealed with a resin-sealing material, The resin sealing material is
A base resin, a curing material, an alkoxysilane compound represented by the following general formula (I), and a crystalline filler having a controlled particle size are included, and the surface layer portion of the semiconductor device and the lead portion are sealed with a resin. An interface between the stopped portion and the resin encapsulating material, and an interface between the semiconductor chip and the resin encapsulating material has a hydrophobizing layer formed by bleeding out of the alkoxysilane compound. (However, any two or more groups among R ^{1 to} R ^{4 in} the general formula (I) represent a methoxy group (CH ₃ O—) or an ethoxy group (C ₂ H ₅ O—), And ^{one of} these R ^{1 to} R ⁴
One or more groups include a methyl group (CH ₃ −), an ethyl group (C ₂ H
₅ −) or a phenyl group (C ₆ H ₅ −) is represented. ).

Here, as the base resin, various resins that have been conventionally used can be used in consideration of an epoxy type, for example, a polyfunctional epoxy resin, a phenol novolac type epoxy resin, a bisphenol type epoxy resin, a cresol novolac type epoxy resin. Can be used alone or in combination. Further, as the curing material, a suitable material suitable for the base resin may be used. In addition, various kinds of alkoxysilane compounds can be considered, and specific examples thereof include diphenyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, and diphenyldiethoxysilane. .

In carrying out the present invention, the content of the above-mentioned alkoxysilane compound is preferably set to a predetermined amount of 2% by weight or less. The reason for this is mainly to reduce the degree of contamination of the semiconductor device mold and to ensure the ease of printing of the semiconductor device after molding. Therefore, the content of the alkoxysilane compound may be more than 2% by weight only for the purpose of improving the moisture resistance.

In addition, it is preferable that the crystalline filler having a controlled particle size is crystalline silica having a particle size (specific surface area) within a predetermined range.

(Operation) The operation of the resin-encapsulated semiconductor device of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing a state of a resin-encapsulated semiconductor device of the present invention. In the resin-sealed semiconductor device of the present invention, when the semiconductor chip 11 (for example, a silicon semiconductor chip) is sealed and molded using a predetermined resin-sealing material, the alkoxysilane compound 13 contained in the sealing material is used. However, it has poor compatibility with other compounding materials,
And since it contains a crystalline filler having a controlled particle size, the resin-sealed semiconductor device surface layer portion, the interface between the semiconductor chip 11 and the sealing material, and the interface between the lead portion 15 and the sealing material. Bleeding out easily occurs, and it tends to exist in the surface layer portion or near these interfaces. However, the alkoxy group of the alkoxysilane compound reacts with the hydroxyl group existing on the surface of the semiconductor chip due to the passivation film or the like, or with the water remaining in the encapsulating material to react with the resin encapsulating semiconductor device surface layer or It seems that a hydrophobic layer will be formed at the interface between the encapsulating material and the semiconductor chip or the like. Therefore, when water tries to enter the inside of the resin-encapsulated semiconductor device from the outside of the resin-encapsulated semiconductor device, this hydrophobization layer seems to prevent the invasion of the moisture. Very low moisture and moisture permeability. When the alkoxysilane compound contains a methoxy group,
The reaction to a hydroxyl group is considered to be explained by the following formula, and the reaction to water is considered to be explained by the following formula.

However, in the formulas and formulas, n = 1 to 3 and m = 1 to 3, and R represents a methyl group (CH ₃ —), an ethyl group, or a phenyl group (C ₆ H ₅ —).

(Example) Hereinafter, an example of a resin-sealed semiconductor device of the present invention (hereinafter, may be abbreviated as a semiconductor device) will be described.
However, it is understood that the chemical names and numerical conditions such as the content thereof described in the following examples are merely examples, and the present invention is not achieved only by these chemicals and numerical conditions. I want to be done.

Example 1 of Sealing Material First, a resin part and a filler part were used. The resin part was composed of a base resin, a curing material, an amine-based curing accelerator, a silane-based coupling agent, a release agent, and a coloring agent (in this case, Carbon), and an alkoxysilane compound as an additive, and one filler part is composed of a crystalline filler having a controlled particle size (specific surface area) and a flame retardant auxiliary material. The encapsulating material of Example 1 having specific composition names and composition ratios of the main components of Example 1 as shown in Appendix 1 was prepared and its physical properties were investigated. Table 2 shows the results of the survey. The base resins listed in Appendix 1 were those of Sumitomo Chemical Co., Ltd. Further, in this case, the filler is crystalline silica (crushed type) showing a particle size distribution with an average value of about 18 μm and a maximum particle size of 120 μm, and is conventionally treated with a conventionally known organic substance and a silane coupling agent. The crystalline silica was used. As the diphenyldimethoxysilane as the alkoxysilane compound, KBM202LS-5300 manufactured by Shin-Etsu Chemical Co., Ltd. was used. However, it is possible that the diphenyldimethoxysilane is mixed with the oligomer component. Further, the adjustment of the sealing material was performed by a conventionally known method. Further, the physical properties listed in Appendix 2 were also measured by known methods.

Example 2 of Encapsulating Material Next, the basic constituent material is the same as the encapsulating material of Example 1, but the filling amount of the filler (crystalline silica) is 70% by weight, and the base resin and Example 2 in which the amount of hardening material is increased
The sealing material of was prepared. On the other hand, the encapsulating materials of Comparative Example 1 to Comparative Example 5, which are different from the encapsulating material of Example 2 only in the points shown in Appendix 3, were prepared. Table 3 shows the respective compositions and the respective physical properties of the encapsulating materials of Example 2 and Comparative Examples 1 to 5. In addition,
"Fused" in the item of the type of filler in Appendix 3 indicates that the filler is fused silica, and "crystal" indicates that the filler is crystalline silica. In addition, “high” in the base resin purity section in Appendix 3 indicates that the base resin has a hydrolyzable chlorine content of 100 ppm or less,
"Pan" means that the base resin has a hydrolyzable chlorine content of about 170 ppm.
It is a thing. Furthermore, the organic additives in the section of additives in Appendix 3 are added to enhance moldability.

Example of Semiconductor Device Next, a semiconductor chip (silicon semiconductor chip) was actually molded using the sealing material of Example 2 to fabricate a semiconductor device of Example. In addition, semiconductor devices of Comparative Examples 1 to 5 were manufactured by using the encapsulating materials of Comparative Examples 1 to 5 to mold the same type of semiconductor chips as the example. The package shape of each of the semiconductor devices of the examples and the comparative examples was an 8-pin SOP (small outline package). Further, the molding was performed by a transfer molding method, and the molding conditions were a mold temperature of 175 ° C. ± 5 ° C., a molding time of 120 seconds, an after cure temperature of 170 ° C., and an after cure time of 6 hours.

Evaluation of Characteristics of Semiconductor Device Next, the characteristics of the semiconductor device according to the present application were evaluated by comparing the characteristics of the semiconductor device of Example 2 with the semiconductor device of Example and Comparative Example 1.
-Evaluation was performed by performing a moisture resistance reliability test on each semiconductor device of each comparative example molded with the sealing material of the comparative example 5.

The humidity resistance reliability test was performed by a high temperature high humidity test (HAST) as an unsaturated test and a pressure cooker test (PCT) as a saturation test. Note that the unsaturated test conditions were that a voltage of 50 V was applied to the semiconductor device in an atmosphere of a temperature of 130 ° C. and a relative humidity of 85%, and the saturation test conditions were a temperature of 120 ° C. and a relative humidity. Humidity is 1
The atmosphere was set to 00% without bias. In addition, as a pretreatment for these tests, in the unsaturated test, the semiconductor device was heated at a temperature of 125 ° C for 16 hours and then heated at 260 ° C.
Process for solder dipping at the temperature of 10 seconds,… After heating the semiconductor device at the temperature of 125 ℃ for 16 hours,
Two levels were set: a moisture absorptive treatment (SOAK) by leaving it for 72 hours in an atmosphere at a temperature of 85 ° C and a relative humidity of 85%, and then a solder dip at a temperature of 260 ° C for 10 seconds. In the saturation test, only the above pretreatment was performed.

Table A shows the unsaturated test results, and Table B shows the saturation test results. Table A shows the semiconductor device of Example and Comparative Example 1
2 shows the result of comparison of median lives of Weibull distribution of the results of the unsaturated test (HAST) of the semiconductor device. Table B shows the cumulative number of defectives with respect to the processing time of the saturation test (PCT). As is clear from Tables A and B, it was confirmed that the semiconductor device of the example exhibited moisture resistance far superior to that of the semiconductor device of the comparative example.

(Effects of the Invention) As apparent from the above description, according to the resin-sealed semiconductor device of the present invention, the surface layer portion of the semiconductor device,
At the interface between the encapsulating material and the semiconductor chip or lead frame, a hydrophobic layer resulting from bleeding out of the alkoxysilane compound is provided, so that the resin-encapsulated semiconductor device can have extremely low water absorption and moisture permeability. I can. Therefore, as is clear from the above experimental results, it is possible to provide a semiconductor device having excellent moisture resistance. Further, even if an epoxy resin having a hydrolyzable chlorine content of 170 ppm is used as a base resin, excellent moisture resistance which has not been obtained can be obtained, and therefore an inexpensive semiconductor device having excellent reliability can be provided. .

[Brief description of drawings]

FIG. 1 is a view for explaining the action of the sealing material of the present invention and a semiconductor device using the same, and is a view schematically showing a cross section of the semiconductor device. 11 ... Semiconductor chip 13 ... Alkoxysilane compound 15 ... Lead part.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 23/29 23/31

Claims (1)

[Claims] 1. A resin-encapsulated semiconductor device in which a part of a lead portion and a semiconductor chip are encapsulated with a resin-encapsulating material, wherein the resin-encapsulating material is a base resin, a curing material, and An alkoxysilane compound represented by the formula (I) and a crystalline filler having a controlled particle size, a surface layer portion of the semiconductor device, a portion of the lead portion sealed with a resin, and the resin sealing material. A resin-encapsulated semiconductor device having a hydrophobization layer formed by bleeding out of the alkoxysilane compound at an interface with the semiconductor chip and an interface between the semiconductor chip and the resin-encapsulating material. (However, any ^one of R ^{1 to} R ^{4 in} the general formula (I) 2
One or more of the groups represents a methoxy group (CH ₃ O-) or an ethoxy group (C ₂ H ₅ O-), and one of these R ¹ to R ⁴
One or more groups include a methyl group (CH ₃ −), an ethyl group (C ₂ H
₅ - represents a) -), or a phenyl group (C ₆ H _5.