JP3167853B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed semiconductor device in which a semiconductor element is resin-sealed with a cured epoxy resin composition, and has excellent heat shock resistance, moisture resistance, low stress and mold release properties. The present invention relates to a semiconductor device having reliability.

[0002]

2. Description of the Related Art IC, LSI, VLSI and ULSI
Are sealed with ceramics, plastics, or the like to form a semiconductor device. Above all, resin encapsulation using a plastic, that is, a resin composition cured product is excellent in mass productivity and the encapsulating material is inexpensive, and thus has become the mainstream of semiconductor element encapsulation.

In recent years, surface-mount type semiconductor devices suitable for high-density mounting as means for increasing the functions and performance of electronic devices have become a major part of the market, and the use ratio thereof has been increasing year by year. . This type of surface mount semiconductor device
The structure is such that the lead pins can be taken out of the device in a planar manner and directly connected to the printed wiring board, which contributes to a reduction in mounting volume.

[0004]

However, in the above-described surface-mount type semiconductor device, if the cured resin composition absorbs moisture before mounting on a printed wiring board, the semiconductor device is soldered. Exposure to a high temperature during mounting causes cracks in the cured body due to the vapor pressure of moisture in the semiconductor device.

[0005] That is, in the surface-mounted semiconductor device 3 as shown in FIG. 1, moisture penetrates into the surface-mounted semiconductor device 3 through the cured resin composition 1 as indicated by an arrow A, and mainly contains Si. It stays on the front surface of the chip 7 and the back surface of the die pad 4. When solder mounting such as vapor phase soldering is performed, the surface-mounted semiconductor device 3 is exposed to a high temperature, so that the retained moisture is vaporized by heating in the solder mounting, and the vapor pressure causes the residual water to evaporate. As shown in (1), the resin cured body portion on the back surface of the die pad 4 is pushed downward to create a gap 5 therein, and at the same time, to generate a crack 6 in the resin cured body 3. [Fig. 1] and [Fig. 2]
, 8 is a wire, generally a gold wire.

As a solution to such a problem of crack generation, a semiconductor element is sealed with a resin composition,
There is a method of sealing the whole obtained semiconductor device and opening and using it before mounting on a substrate. In addition, for example, 10
A method of removing water by drying at 0 ° C. for 24 hours and then performing solder mounting has been proposed and has been already implemented. However, according to such a pretreatment method, there is a disadvantage that the process of mounting the substrate becomes complicated.

On the other hand, attempts have been made to reduce the water absorption of a cured resin composition constituting a surface-mounted semiconductor device to prevent cracks. However, such a cured product of a low water-absorbing epoxy resin composition has high-temperature storage characteristics such as reliability of moisture resistance such as corrosion of a conductor wiring portion of a semiconductor element and an increase in conductor resistance due to formation of a conductor intermetallic compound at a high temperature. This was found to be inferior by a subsequent examination by the present inventors.
That is, it is necessary to improve the reliability of the low-water-absorbing epoxy resin composition as a whole.

The present invention has been made in view of such circumstances, and does not require any pretreatment before mounting on a substrate, and furthermore, has a thermal shock resistance such that a crack is not easily generated in a cured resin composition during solder mounting. It is an object of the present invention to provide a surface-mount type semiconductor device which is excellent in low stress, moisture resistance, and overall reliability.

[0009]

In order to achieve the above object, a semiconductor device of the present invention comprises a semiconductor element sealed with an epoxy resin composition containing the following components (A) to (E). Take the configuration. (A) An epoxy resin represented by the following structural formula [Formula 6].

Embedded image (B) A phenolic resin represented by the following structural formula [Formula 7].

Embedded image (C) a curing accelerator represented by the following general formula [Formula 8].

Embedded image (D) An organopolysiloxane represented by the following general formula [Formula 9].

Embedded image (E) an inorganic filler.

In order to prevent the occurrence of cracks in the cured resin composition, the absorption of moisture into the cured resin composition is generally suppressed. The adhesive strength between the back surface of the die pad and the surface of the Si chip (semiconductor element) and the cured resin composition is increased. The strength of the cured resin composition at a high temperature during solder mounting is increased. It is considered that consideration should be given to reducing the elastic modulus of the cured resin composition at a high temperature during solder mounting.

In the present invention, while taking the above matters into consideration,
With the above configuration, improvement in crack resistance and low stress during solder mounting were simultaneously achieved. It was also found that the overall reliability was excellent, and the present invention was reached.

As the epoxy resin (A) component, an epoxy resin represented by the above-mentioned structural formula [Chemical Formula 6] is used. However, as long as the crack resistance of the cured resin composition at the time of solder mounting is not reduced, a conventionally known bispheno resin is used. Glycidyl ether type epoxy resin such as phenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, fat An epoxy resin having two or more epoxy groups in one molecule such as an aromatic epoxy resin, an alicyclic epoxy resin, and a heterocyclic epoxy resin can be used in combination. In this case, the content of the epoxy resin of the structural formula [Formula 6] is 5% of the total epoxy resin.
0% by weight or more. Among the epoxy resins described above, a resin having a biphenyl skeleton is preferable as the resin for the surface mount semiconductor device.

The above specific phenol resin (B) component comprises:
It is represented by the structural formula [Formula 7] and functions as a curing agent component of the epoxy resin. By using a resin having a skeleton structure as shown in [Formula 7], it is possible to reduce the moisture absorption of the cured resin composition.

The special phenolic resin represented by the above formula (I) has a hydroxyl equivalent of 120 to 190 and a softening point of 80.
It is preferable to use one having a temperature of up to 130 ° C. The above-mentioned specific phenol resin may constitute the curing agent component itself, or may be used in combination with other commonly used phenol resins.

In the former case, all of the curing agent components are composed of the specific phenolic resin represented by the above-mentioned structural formula [Chemical formula 7], and in the latter case, a part of the curing agent components are [Chemical formula 7] ] Of the specific phenolic resin.

The novolak type pheno generally used
The hydroxyl resin has a hydroxyl equivalent of 70 to 150 and a softening point of 50.
It is preferable to use one having a temperature of up to 110 ° C. When a specific phenol resin represented by the above-mentioned structural formula [Chemical formula 7] is used in combination with such a commonly used phenol resin, the specific phenol resin is used as a curing agent component. 50
% By weight or more, particularly preferably 7% by weight.
0% by weight or more.

The mixing ratio of the epoxy resin to the phenol resin is preferably such that the hydroxyl groups in the phenol resin are 0.8 to 1.2 equivalents per equivalent of epoxy group.

The curing accelerator (C) component used together with the epoxy resin and the phenol resin is an organic phosphine compound represented by the above general formula [8].

In particular, R ₁ is preferably hydrogen, a methyl group, or a methoxy group in terms of the solder heat resistance of the cured resin composition constituting the surface-mount type semiconductor device (there is no occurrence of cracks during solder mounting). The amount of the curing accelerator represented by the above [Chemical Formula 8] is 0.1 to 0.1 parts by weight of the total amount of the epoxy resin and the phenol resin.
It is preferable to set the ratio to 20 parts by weight. It is preferably 0.5 to 10 parts by weight. That is, when the amount is less than 0.1 part by weight, it is difficult to obtain solder heat resistance to a desired cured resin composition, and when the amount exceeds 20 parts by weight, electrical characteristics at high temperatures are deteriorated, thereby deteriorating moisture resistance reliability. This is because there is a tendency.

Further, in the present invention, the organopolysiloxane (D) represented by the above-mentioned general formula [Chemical Formula 9] is contained for the purpose of improving the electrical insulation property of the semiconductor device at the time of high-temperature moisture absorption.

It is preferable that the compounding amount of the organopolysiloxane represented by the chemical formula 9 is set to 0.01 to 1.0 parts by weight based on 100 parts by weight of the total amount of the inorganic filler. , Especially 0.5 parts by weight or less gives good results. That is, when the content is 1.0 part by weight or more, there is a possibility that various properties other than the electrical insulation property are adversely affected.

As the above-mentioned inorganic filler (E), it is preferable to use a fused silica powder or a crystalline silica powder, and it is preferable to use a powder excluding coarse powder having a particle size of 200 mesh or more. The shape of the filler can be appropriately selected as required, such as a spherical shape or a square shape obtained by crushing. In addition, the content of radioactive elements such as uranium and thorium contained in the filler, alkali metals, alkaline earth metals and their ions, and furthermore, the content of anions including halogen ions is preferably as small as possible. It is determined by the type of the semiconductor device.

The amount of the inorganic filler is preferably set in the range of 65 to 95% by weight, particularly preferably in the range of 75 to 92% by weight, based on the entire epoxy resin composition. That is, if the amount of the inorganic filler is less than 65% by weight, the amount of moisture absorbed by the cured resin composition increases, and the strength at high temperatures decreases, so that crack resistance during solder mounting tends to be inferior. If the content exceeds 95% by weight, the melt viscosity of the resin composition tends to increase at the time of transfer molding, and there is a tendency that molding failure such as unfilling or wire flow occurs in the cavity.

Further, in the present invention, as a release agent,
Conventionally known long-chain carboxylic acids such as stearic acid, behenic acid and montanic acid, and metal salts such as zinc, aluminum, calcium, etc., esters, amides or polyolefin-based mold release agents using the same as a raw material. Or in combination. The mixing ratio of such a release agent is 0.1 to
3.0% by weight is preferred. More preferably, 0.5 to
2.0% by weight. That is, if it is less than 0.1% by weight, it is difficult to obtain a desired release property. Conversely, if the content exceeds 3.0% by weight, the solder crack resistance tends to decrease.

A particularly preferred release agent among the above-mentioned polyolefin release agents is oxidized polyethylene wax (F). This oxidized polyethylene wax has a feature of being excellent in continuous moldability as compared with other general-purpose release agents. This oxidized polyethylene wax is, for example, synthesized by partially oxidizing a low-grade polyethylene wax. And, in the above-mentioned oxidized polyethylene wax, the acid value is 13 to 30, the drop point (the temperature at which it melts and forms a droplet) is 90 to 130 ° C., and the DGF-M-IV2 [D
It is preferable to use those having a saponification value of 20 to 120 as measured according to IN 53401 or ASTM D1387].

The compounding ratio of the oxidized polyethylene wax is preferably 0.1 to 3.0% by weight based on the whole epoxy resin composition, similarly to the other release agents. More preferably, it is 0.5 to 2.0% by weight. That is, 0.
If the amount is less than 1% by weight, it is difficult to obtain a desired release property, and as a result, the productivity may be reduced. Conversely, 3.0% by weight
If the ratio exceeds the above range, the productivity is improved, but the solder crack resistance tends to decrease.

In the present invention, when a specific phenol resin represented by the above-mentioned structural formula [Formula 7] is used, an organofunctional silane compound represented by the following general formula [Formula 10] is used in advance. Can be used as a reactant, or can be used in a lump, that is, separately. That is, by appropriately selecting and using an organofunctional silane compound represented by the following general formula [Chemical Formula 10] and reacting it with a part or all of the above-mentioned specific phenol resin, a resin composition at the time of solder mounting is obtained. It is possible to increase the high-temperature strength of the cured body and to improve the adhesive strength to the semiconductor element surface. That is, the effect that the improvement of the thermal shock reliability becomes more remarkable can be achieved.

Embedded image

The reaction between the organofunctional silane compound and the above-mentioned specific phenolic resin is carried out at a temperature higher than the melting temperature of the specific phenolic resin, ie, alcohols such as methanol and ethanol. It may be performed until the components can be removed from the reaction system. Usually from 150 ° C to 19
15 to 300 minutes at a temperature of 0 ° C., preferably 170 ° C.
The reaction is carried out at a temperature of from 180 to 180 ° C for a period of from 20 to 90 minutes. In this reaction, an organic phosphine compound represented by the general formula [Formula 8] may be used as a reaction catalyst.

When producing a reaction product of an organofunctional silane compound and the above-mentioned specific phenol resin,
The compounding amount of the organofunctional silane compound represented by the general formula [Chemical Formula 10] may be a specific phenol resin 100
It is preferable to set the ratio to 0.1 to 10 parts by weight with respect to parts by weight. That is, if less than 0.1 part by weight, it is difficult to obtain the thermal shock reliability of the obtained cured resin composition,
Conversely, if the amount exceeds 10 parts by weight, the risk of gelling during the reaction between the organofunctional silane compound and the specific phenol resin increases.

In the present invention, an ion trapping agent such as a hydrotalcite compound or antimony pentoxide can be used for the purpose of improving the humidity resistance and the high-temperature storage characteristics.

Such a hydrotalcite compound is represented, for example, by the following general formula [Formula 11].

Embedded image

On the other hand, antimony pentoxide is represented by Sb ₂ O ₅ and may be anhydrous or a hydrate containing water of crystallization.

The above-mentioned hydrotalcite compounds and antimony pentoxide may be used as they are, or may be separately surface-coated with a silane coupling agent. Alternatively, a pre-dispersed part of the organic component of the present invention using a heat roll or the like may be used.

The compounding amount of the hydrotalcite compound or antimony pentoxide is 0.5 to 15 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the phenol resin.
It is preferable to set the ratio to parts by weight, and particularly to set the ratio to 10 parts by weight or less. That is,
If the amount is 15 parts by weight or more, various properties other than the moisture resistance reliability and the high-temperature storage properties are adversely affected.

The epoxy resin composition used in the present invention comprises the above components (A) to (E), and optionally (F)
Additives may be added to the components. As additives, release agents, hydrotalcite compounds,
There are antimony pentoxide, flame retardants, flame retardant aids, coupling agents and coloring agents.

As the flame retardant and the flame retardant auxiliary, compounds such as a novolak type brominated epoxy resin, a bisphenol A type brominated epoxy resin, and antimony trioxide can be appropriately used alone or in combination.

Examples of the coupling agent include a silane coupling agent.

Further, in the present invention, in addition to the above components, various elastomers such as silicone rubber and synthetic rubber can be blended to reduce the stress.

The epoxy resin composition used in the present invention comprises:
For example, it can be manufactured as follows. That is, the main components of the epoxy resin component, the phenol resin component (including those partially reacted with the organofunctional silane compound and those completely reacted with the organofunctional silane), the curing accelerator component and the inorganic filler After appropriately mixing the components and other additives such as a release agent, the mixture is kneaded at a temperature of 80 ° C. to 120 ° C. to a semi-cured state by a roll machine or a kneader. Next, the desired epoxy resin composition can be produced by a series of steps of pulverizing by known means and tableting as necessary. Prior to the kneading, it is preferable to grind solids in the raw materials and dry-blend all components.

The method for sealing the semiconductor element using such an epoxy resin composition to obtain the semiconductor device of the present invention is not particularly limited, and a conventionally known mold such as ordinary transfer molding is used. It can be performed by molding.

[0041]

As described above, the semiconductor device obtained by the present invention does not require any pre-treatment when mounted on an electronic device, and does not have cracks in the cured resin composition during solder mounting. It is excellent in low stress, moisture resistance reliability, and overall reliability. Further, when polyethylene oxide wax is used as the release agent, the productivity is improved because continuous moldability is excellent.

First, prior to the examples, the following components were prepared. "Epoxy resin A" is an epoxy resin represented by the following structural formula [Formula 12], having an epoxy equivalent of 200 and a softening point of 73.
° C.

Embedded image "Epoxy resin B" is an epoxy resin represented by the following structural formula [Formula 13], having an epoxy equivalent of 200 and a softening point of 10
0 ° C.

Embedded image

"Phenol resin C" has the following structural formula:
4] is a phenolic resin having a hydroxyl equivalent of 18
0, softening point 120 ° C.

Embedded image "Phenol resin D" is a phenol resin represented by the following structural formula [Formula 15], having a hydroxyl equivalent of 110 and a softening point of 8
2 ° C.

Embedded image

"Curing accelerator" Organic phosphine compound a
Is a triphenylphosphine in which R ₁ of the formula [8] is hydrogen. The organic phosphine compound b is a compound represented by the formula ( ₁₎
Is a methyl group. DBU has the following structural formula:
1,8-diazabicyclo (5,4,0) undecene-7.

Embedded image "Organopolysiloxane" is an organopolysiloxane represented by the following structural formula [Formula 17], having an amine equivalent of 4
50, average molecular weight 900.

Embedded image

"Organofunctional silane E" An organofunctional silane E represented by the following structural formula [Formula 18].

Embedded image "Organofunctional silane F" Organofunctional silane F represented by the following structural formula [Formula 19].

Embedded image

"Reaction product of organofunctional silane E and phenolic resin C" 0.15 parts by weight of organofunctional silane E was added to 100 parts by weight of phenolic resin C heated and melted at 175 ° C, and 175 ° C
After stirring by heating and melting for 1 hour, the mixture was cooled to room temperature and used. "Reaction product of organofunctional silane F and phenol resin C" 0.15 parts by weight of organofunctional silane F was added to 100 parts by weight of phenol resin C heated and melted at 175 ° C, and added at 175 ° C. After stirring by heating and melting for an hour, the mixture was cooled to room temperature before use.

"Oxidized polyethylene wax" PED-521 manufactured by Hoechst (acid value 15, dropping point 105 ° C) was used. "Release agent a" Hoechstwax OP (acid value 12, dropping point 1)
00 ° C.). "Release agent b" carnauba wax (acid value 5, drop point 83 ° C)
Was used.

[0048]

The present invention will be described below with reference to examples. Examples 1 to 13 and Comparative Examples 1 to 5 The components shown in the following [Table 1], [Table 2] and [Table 3] were blended in the proportions shown in the table, and mixed mixin (temperature 1)
(00 ° C.) for 10 minutes, cooled and solidified, and then pulverized to obtain an intended epoxy resin composition.

[Table 1]

[Table 2]

[Table 3]

A semiconductor device was obtained by molding a semiconductor element by transfer molding using the powdery epoxy resin composition thus obtained. This semiconductor device is an 80-pin four-way flat package (QFP).
[Size: 20mm x 14mm x thickness 2.5mm]
7mm x 7mm die pad, 6.5mm x 6.5mm
Having an Si chip.

The semiconductor device thus obtained was immersed in solder at 260 ° C. for 10 seconds, and the critical moisture absorption time at 85 ° C./85% RH until cracking of the cured resin composition was measured. . Further, using the epoxy resin compositions obtained in the above Examples and Comparative Examples, a thickness of 1 m
A disk-shaped cured product having a diameter of 50 mm and a diameter of 50 mm was prepared (curing condition: 180 ° C. × 5 hours). It was measured.

Further, the flexural strength and flexural modulus of the cured product were measured at room temperature and 260 ° C. according to JIS K-6911 5.17.

Further, the semiconductor device obtained in the same manner as described above using the epoxy resin compositions obtained in the above Examples and Comparative Examples was subjected to moisture absorption at 85 ° C./85% RH for 72 hours, and then 260 ° C. × 10 The solder was immersed for 2 seconds. This one
The substrate was left at 21 ° C. × 100% RH (hereinafter, referred to as “SDPCT test”) to remove the aluminum pattern on the surface of the semiconductor element.
The moisture resistance deterioration time, which occurred at 50% failure due to the corrosion of the contact portion, was measured.

Further, the semiconductor device obtained in the same manner as above was allowed to stand at 131 ° C. × 85% RH while applying a voltage of 30 volts (hereinafter referred to as a “bias application test”), and the surface of the semiconductor element was exposed. The moisture resistance deterioration time at which the wiring resistance value due to corrosion of the aluminum pattern portion becomes three times or more was measured.

Next, the semiconductor device obtained in the same manner as described above was subjected to a temperature cycle test at 150 ° C./5 minutes to −60 ° C./5 minutes (hereinafter referred to as “TCT test”) for 300 minutes.
The cycle was performed, and the amount of deformation of the aluminum pattern on the surface of the semiconductor element due to the thermal stress received from the cured resin composition was measured.

Next, the semiconductor device obtained in the same manner as above was allowed to stand at 225 ° C., and the resistance change rate of the aluminum pattern on the surface of the semiconductor element was measured. The aging time was measured.

Next, with respect to the epoxy resin compositions of Examples and Comparative Examples, the releasability of the cured products was evaluated. The evaluation method of the releasability was performed as follows. That is,
FIG. 3 shows a three-layer structure (upper die 10, middle die 11,
Using the lower mold 12), 10 shots were molded. Then, the load at the time of release from the cured resin composition of the tenth shot was measured. In FIG. 3, 13
Is a cull, 14 is a sprue, 15 is a runner, and 16 is a cavity. As shown in FIG. 4, the load at the time of release was measured by placing the middle mold 11 of the molding die on the support 17.
Using the push-pull gage 18, the cured resin composition 19 in the middle mold 11 was released from above. The load value at this time,
That is, the release load was measured. Then, the continuous formability was evaluated from the value. When the continuous formability was very excellent, it was evaluated as ◎, and when it was excellent, it was evaluated as ○.

The results are shown in [Table 4], [Table 5], [Table 6] and [Table 7].

[Table 4]

[Table 5]

[Table 6]

[Table 7]

From the results of [Table 4] to [Table 7], the product of the example has a lower saturated water absorption than the product of the comparative example, and is excellent in the properties of the cured product. In addition, the limit moisture absorption time and 50% failure occurrence time of crack generation of the cured resin composition of the example product are longer than those of the comparative example product, and the amount of wiring deformation is small. . From this, it can be seen that the products of Examples are excellent in thermal shock reliability, humidity resistance and low stress of the cured product. In addition, when the oxidized polyethylene wax was used, it was found that the releasability, that is, the continuous moldability was excellent.

[0059]

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view illustrating a state of occurrence of cracks in a cured resin composition of a surface-mounted semiconductor device.

FIG. 2 is a vertical cross-sectional view illustrating a state of occurrence of cracks in a cured resin composition of a surface-mounted semiconductor device.

FIG. 3 is a longitudinal sectional view of a molding die for producing a release load test piece of a cured resin composition.

FIG. 4 is a longitudinal sectional view illustrating a release load test of a cured resin composition.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuhiro Ikemura 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nippon Denko Co., Ltd. Examiner Hideo Sakai (56) References JP-A-4-202555 (JP, A) JP-A-5-9265 (JP, A) JP-A-4-55422 (JP, A) JP-A-5-343570 (JP, A) JP-A-4-318056 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) H01L 23/29 C08G 59/00-59/72

Claims (4)

(57) [Claims] 1. A semiconductor device comprising a semiconductor element encapsulated with an epoxy resin composition containing the following components (A) to (E). (A) An epoxy resin represented by the following structural formula [Formula 1]. Embedded image (B) A phenolic resin represented by the following structural formula [Formula 2]. Embedded image (C) a curing accelerator represented by the following general formula [Formula 3]. Embedded image (D) An organopolysiloxane represented by the following general formula [4]. Embedded image (E) an inorganic filler. 2. A semiconductor device comprising a semiconductor element encapsulated with an epoxy resin composition containing the components (A) to (E) and the oxidized polyethylene wax (F) according to claim 1. 3. The semiconductor device according to claim 1, wherein a part or all of the phenol resin is a reaction product with an organofunctional silane compound represented by the following general formula [5]. . Embedded image 4. The semiconductor device according to claim 1, wherein the ion trapping agent contains at least one selected from hydrotalcite compounds and antimony pentoxide.