JPH0885718A - Semiconductor device - Google Patents

Abstract

PURPOSE: To enable the prevention of cracks on a passivation film, deformation of aluminum wires, etc., in a semiconductor device to thereby obtain a highly reliable semiconductor device. CONSTITUTION: A semiconductor device is sealed with an epoxy resin compsn. contg. an epoxy resin, a phenol novolak resin, and an inorg. filler as the essential components. The compsn. further contains a reaction product which is formed by adding an aminopropyl-terminated dimethylsiloxane having a mol.wt. of 2,000-20,000 and an Si content of 20-25wt.% to an epoxy resin to react the dimethylsiloxane with the resin and in which the dimethylsiloxane is dispersed in and chemically bonded to a matrix comprising the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device which is provided with a sealing resin excellent in low stress and has extremely improved reliability.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs and LSIs are sealed with ceramics or resin from the viewpoint of mechanical strength and moisture resistance. Among them, the ceramic package has good moisture resistance and heat dissipation, and therefore, highly reliable encapsulation can be performed, whereby a highly reliable semiconductor device can be obtained. However,
Since ceramic materials are expensive and have a drawback of being inferior in mass productivity, the sealing of semiconductor elements with resin has become the mainstream these days.

Among these resins, an epoxy resin composition has been favored. However, due to high integration and upsizing of semiconductor elements represented by DRAM and MPU, obstacles caused by heat generated when a semiconductor device is used. In addition, the thermal stress applied to the semiconductor element is increasing, and defects such as cracks in the passivation film of the semiconductor element and deformation of aluminum wiring are likely to occur. I am worried about the point. Therefore, there is a strong demand for improving the thermal conductivity and reducing the thermal stress of the sealing resin, and development of such a resin is particularly desired.

[0004]

In response to the above demands, epoxy resin compositions for low stress semiconductor encapsulation include epoxy resins, novolac type phenolic resin curing agents, release agents and stress reducing agents. Epoxy resin compositions containing the above rubber components are widely used. However, using such a low stress epoxy resin composition,
The semiconductor device obtained by transfer molding does not meet the requirement for low stress required for the resin-encapsulated semiconductor device, and does not have satisfactory low stress. Further, in the case of transfer molding using the epoxy resin composition as described above, a softening agent such as rubber is detached from the surface of the semiconductor device to be molded and causes mold stains. There are also difficulties. On the other hand, the same dimethyl siloxane as used in the synthesis of the component (A) in the present invention is used, and this and a novolac type epoxy resin are pre-reacted in methyl ethyl ketone (MEK) to form so-called silicone gel particles, which are The technique of blending into an epoxy resin composition as a stressing agent is described as an example in the prior invention (JP-A-58-2).
1417 publication). However, in the thus obtained epoxy resin composition containing the silicone gel particles, since the silicone gel particles are in the form of particles and are independently present in the free state, the silicone gel particles are still present during transfer molding. Is detached, which causes the mold to be contaminated.

The present invention has been made in view of the above circumstances, and provides a highly reliable semiconductor device which is free from mold stains and the like at the time of manufacture and has excellent low stress. To aim.

[0006]

In order to achieve the above object, a semiconductor device of the present invention is an epoxy resin composition containing an epoxy resin, a phenol novolac resin and an inorganic filler as essential components. A semiconductor element is sealed with an epoxy resin composition containing the component A). (A) Epoxy resin having a terminal molecular weight of aminopropyl group 2000 to 200
No. 00 dimethyl siloxane (Si content 20 to 25% by weight) is added and reacted, and the above dimethyl siloxane is dispersed in the mother phase composed of the above epoxy resin in a state of being chemically bonded to the mother epoxy resin. Reaction products.

That is, the present inventor has conducted a series of researches based on the above-mentioned prior invention (see Japanese Patent Laid-Open No. 58-21417), and as a result, the same dimethylsiloxane as used in the prior invention was used as a novolac type epoxy resin or the like. When added and blended in an epoxy resin and reacted, the above-mentioned epoxy resin is used as a mother phase, and dimethylsiloxane produces 1 to 10 μm of silicone gel particles in the mother phase, and the generated silicone gel particles become the mother phase. It was found that a so-called sea-island structure is formed in which the epoxy resin is dispersed in a state of being chemically bonded. When the modified epoxy resin having such a sea-island structure is used in place of at least a part of the epoxy resin used in the epoxy resin composition, the generation of mold stains is prevented, and the stress is low. It was found that the nature will be realized, and the invention was reached.

The epoxy resin composition used in the present invention is
It contains the modified epoxy resin as the component (A).

The component (A) is, for example, a novolac type epoxy resin and dimethylsiloxane having an aminopropyl group at the terminal and a molecular weight of 2000 to 20000 (Si content of 20 to 25% by weight), and is represented by the following general formula ( And those represented by 1).

[0010]

Embedded image

The epoxy resin to be reacted with the dimethylsiloxane is not particularly limited, but good results can be obtained by using a novolac type epoxy resin having an epoxy equivalent of 190 to 210, particularly a cresol novolac type epoxy resin. . However, a bisphenol novolac type epoxy resin or the like can also be used. Is. Then, in reacting such an epoxy resin with the dimethyl siloxane, by pre-reacting 75 parts by weight of an epoxy resin such as a novolac type epoxy resin (hereinafter abbreviated as “part”) with 25 parts of the dimethyl siloxane, A modified epoxy resin having a sea-island structure in which a silicone rubber having a particle diameter of 1 to 10 μm is dispersed in an epoxy resin matrix can be obtained. This will be described in more detail. For example, the above-mentioned dimethyl siloxane was added to the o-cresol novolac type epoxy resin melted at 160 to 180 ° C. in the ratio described above, and a disperser type disperser for 2 to 6 hours was used. It can be obtained by dispersing, mixing and reacting. The ratio of the epoxy resin as the mother phase to the dimethylsiloxane is not limited to the ratio described above. The former is 60 to 90 parts, and the latter is 4 parts.
It can be freely selected within a range of 0 to 10 parts. Especially preferred is the latter in a proportion of 25 to 10 parts. Within the above range, a modified epoxy resin having a sea-island structure in which silicone rubber is dispersed in the epoxy resin matrix can be obtained.

The modified epoxy resin of the component (A) obtained as described above may be used in place of all of the unmodified epoxy resins usually used in epoxy resin compositions, or part thereof. You may use it instead. When it is used in place of a part, it is preferable that the proportion is about 85 to 70% by weight (hereinafter abbreviated as “%”). In this case, the modified epoxy resin and the unmodified epoxy resin may be the same or different from each other. From the viewpoint of low stress and the like, it is preferable to set such a modified epoxy resin so as to be 10 to 15% of the whole epoxy resin composition.

When the modified epoxy resin and the unmodified epoxy resin are used in combination, the unmodified epoxy resin is not particularly limited, but a novolac type epoxy resin having an epoxy equivalent of 190 to 210 is used. It is preferable.

Phenol novolac resins and cresol novolac resins having a softening point of 70 ° C. or higher are used as curing agents for the above-mentioned modified epoxy resin and non-modified epoxy resin. The compounding ratio of the phenol resin curing agent and the whole epoxy resin including the modified epoxy resin is preferably set so that the epoxy equivalent / hydroxyl equivalent is in the range of 0.9 to 1.2. is there. The closer the equivalence ratio is to 1, the better the result.

In addition to the above component raw materials, an inorganic filler is used in the epoxy resin composition used in the present invention. As such an inorganic filler, it is preferable to use a spherical filler having a particle diameter of 100 μm or less (major axis a, minor axis b, b / a = 0.5 to 1.0). It is preferable that the usage ratio is about 2.0 to 2.5 times the weight of the total amount of the resin. The material of the spherical filler is not particularly limited, but spherical silica powder is generally used. By using such a spherical filler having a particle diameter of 100 μm or less, the low stress effect is increased, and at the same time, the damage of the passivation film of the semiconductor element due to the inorganic filler can be prevented.

In addition, an organic nitrogen compound can be used as an optional component in the epoxy resin composition used in the present invention. Such an organic nitrogen compound is represented by the following general formula (2), and when such an organic nitrogen compound is blended in a proportion of 0.21 to 0.16% of the whole epoxy resin composition, This acts as a curing catalyst for the epoxy resin, and a sealing resin having high water resistance can be obtained.

[0017]

Embedded image

If necessary, the epoxy resin composition used in the present invention contains additives such as metal salt wax of long-chain fatty acid as a release agent and a colorant, which are usually used in epoxy resin compositions. It The epoxy resin composition used in the present invention can be produced by a conventionally known method using the above raw materials, for example, the raw materials are uniformly dispersed and mixed by a method of either dry blending or melt mixing, and pulverized, It can be obtained by tableting as needed.

The semiconductor element can be sealed with the epoxy resin composition thus obtained by a conventional method, for example, a known molding method such as transfer molding, whereby the semiconductor of the present invention is formed. The device is available.

When molding such as transfer molding is carried out in this manner, the epoxy resin composition is not detached because the dimethylsiloxane is in a state of being chemically bonded to the epoxy resin of the mother phase, and therefore the mold is not separated. Does not stain.

[0021]

As described above, in the semiconductor device of the present invention, when the resin is sealed as described above, the mold resin is not contaminated, and the function of the modified resin as the component (A) makes the sealing resin excellent. It has a low stress property, which makes it highly reliable. That is, according to the present invention, it is possible to sufficiently deal with semiconductor devices that are highly integrated and large in size, and prevent occurrence of cracks, deformation of aluminum wiring, etc. with respect to the passivation film of the semiconductor device. it can.

Next, examples will be described in detail together with comparative examples.

[0023]

Examples 1 to 3 First, 75 parts of o-cresol novolac epoxy resin was melted at 160 to 180 ° C., and dimethylpolysiloxane represented by the general formula (1) having a molecular weight of about 10,000 (silica content 20 -25%) to 75 parts of epoxy resin and 25 parts of dimethylpolysiloxane
It was added in a ratio of parts. 160-1 in that state
Stir and mix with a disperser at a temperature of 80 ° C. for 3 hours,
The reaction product was cooled and then pulverized to prepare a modified resin. This is referred to as modified resin a. Next, this modified resin a
And the raw materials shown in Table 1 below are mixed in the proportions shown in the same table,
The mixture was placed on a mixing roll machine heated to 80 ° C., kneaded for 10 minutes, and then formed into a sheet. Then, this sheet-like body was cooled and pulverized to prepare an epoxy resin composition powder.

[0024]

Comparative Example 1 Silicone gel particles were prepared in the same manner as in the example of the prior invention (Japanese Patent Laid-Open No. 58-21417), and these were blended in the epoxy resin composition at the same ratio to prepare a modified resin b. An epoxy resin composition powder was prepared in the same manner as in the above example except that the modified resin b was used in place of the modified resin a.

[0025]

Comparative Example 2 Instead of the modified resin a, a phenol novolac epoxy resin was used. Except for this, the epoxy resin composition powder was prepared in the same manner as in the above example.

[0026]

[Table 1]

Using the epoxy resin composition powders obtained in the above Examples and Comparative Examples, the following tests were conducted to evaluate the performance of semiconductor devices.

[0028]

[Table 2]

[0029]

[Table 3]

A 42-pin DIP package was formed under the same molding conditions as the measurement of the package crack occurrence rate, and a thermal shock resistance test was performed by a 2-minute cycle of -80 ° C and 200 ° C. )
Was measured. The mounted chip size is 6.0 x 3.0 x
The amount of slide of Al was 0.43 t, and after the thermal shock resistance test was completed, the package was disassembled with hot fuming nitric acid, and the amount of slide was measured using an electron microscope.

[0031]

[Table 4]

[0032]

[Table 5]

As is clear from Tables 2 to 5, the semiconductor device resin-sealed with the molding material according to the above-mentioned embodiment is
It can be seen that the sealing resin is excellent in low thermal stress, so that the number of package cracks, the amount of Al slide, and the number of passivation cracks are small, and that the transfer mold molding does not cause mold contamination.

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

Claims (5)

[Claims] 1. A semiconductor element is encapsulated with an epoxy resin composition containing an epoxy resin, a phenol novolac resin and an inorganic filler as essential components, the epoxy resin composition containing the following component (A). A semiconductor device characterized by the following. (A) Epoxy resin having terminal molecular weight of aminopropyl group 2000 to 20000
Dimethyl siloxane (Si content 20-25% by weight)
A reaction product in which the dimethylsiloxane is dispersed in the mother phase composed of the epoxy resin in a state of being chemically bonded to the epoxy resin of the mother phase, which is obtained by adding and reacting. 2. The semiconductor according to claim 1, wherein the component (A) is a reaction product obtained by reacting 75 parts by weight of the novolac type epoxy resin with 25 parts by weight of the terminal aminopropyl group-containing dimethylsiloxane. apparatus. 3. The semiconductor device according to claim 1, wherein the component (A) is contained in the epoxy resin composition in an amount of 10 to 15% by weight. 4. The semiconductor device according to claim 1, wherein the inorganic filler is a spherical filler having a particle diameter of 100 μm or less. 5. The semiconductor device according to claim 1, further comprising an organic nitrogen compound as an optional component.