JP3262918B2 - Sealing material, sealing method, and semiconductor device using sealing material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device sealing material,
The present invention relates to a method and a semiconductor device for improving the reliability of a semiconductor element.

[0002]

2. Description of the Related Art Various sealings are performed on semiconductor elements such as ICs and LSIs for the purpose of protection from external environments such as temperature, humidity and impact, and electrical insulation. Compared with the method of sealing using glass, metal, or ceramic, the method of sealing with a thermosetting resin is economically advantageous and is widely used.

As a sealing resin composition, an epoxy resin composition is most commonly used among thermosetting resin compositions in terms of reliability and price.

[0004] In recent years, the trend toward smaller and thinner packages has been rapidly progressing with high integration and multifunctional IC packages, and the trend toward surface mounting packages has been progressing along with streamlining of packaging. As technological innovations have progressed, demands on sealing materials have become more stringent.

As an epoxy resin for encapsulation, an epoxy resin obtained by reacting phenol or novolak resin with epichlorohydrin is used. Usually, since impurities such as chlorine are contained in the resin, free chlorine ions are released. However, there is a problem that the internal wiring, patterns and the like are corroded.
For this reason, electronic components sealed with such a sealing material using an epoxy resin may have reduced functions such as reduced insulating properties and increased leakage current during use, and may cause a reduction in reliability of the electronic components. Is hiding.

[0006] Epoxy resin manufacturers have responded to the demand for higher quality encapsulants due to technological innovation in the semiconductor field by purifying the epoxy resin to an extremely high purity.

Further, as disclosed in Japanese Patent Application Laid-Open No. 61-1976621, a semiconductor element encapsulating material using a solid epoxy containing no chloride ion has been studied, but the tendency of surface mounting type packaging is increasing. As it proceeds, it has a defect that it has high hygroscopicity and easily cracks when dipped in solder as compared with an epoxy resin obtained by reacting phenol or novolak resin with epichlorohydrin.

[0008]

As long as the epoxy resin derived from epichlorohydrin is used, impurities such as chlorine are usually contained in the resin. It is considered that there is a danger that the reliability of the electronic component is reduced due to a decrease in function due to a decrease in insulation and an increase in leak current.

In view of such a situation, the present inventors have made intensive studies, and as a result, found that the reliability of a semiconductor element is improved by sealing using the semiconductor element sealing material of the present invention. Was.

[0010]

According to the present invention, there is provided a resin composition comprising: (A) 95 to 50 parts by weight of an epoxy resin having a glycidyl group and (B) at least one epoxy group having a lower reactivity with a curing agent than the glycidyl group. Encapsulating material comprising 5 to 50 parts by weight of a polyvalent epoxy resin and (C) a curing agent as essential components "," A method for improving the reliability of a semiconductor element by using the encapsulating material " And "Semiconductor device using the same sealing material".

The epoxy resin (A) having a glycidyl group used as an essential component of the encapsulating material of the present invention is a general glycidyl type epoxy resin used for a semiconductor element encapsulating material, for example, a cresol novolac type epoxy resin. Phenol novolak type epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, and the like, and may include a flame retarded bromine epoxy resin.

The polyepoxy resin having at least one epoxy group having a lower reactivity with the curing agent than the glycidyl group (B) used as the second essential component is an alicyclic epoxy group or an aliphatic epoxy group. And a polyvalent epoxy resin having an aliphatic epoxy group. Moreover, even if it is a glycidyl group, if it has two or more types of glycidyl groups having different reactivity with the curing agent, it has at least one epoxy group having lower reactivity with the curing agent than the glycidyl group. Although a polyvalent epoxy resin can be used instead of the polyvalent epoxy resin, a resin having as few impurities as possible such as chlorine ions is desirable.

(B) An example of a polyvalent epoxy resin having at least one epoxy group having a lower reactivity with a curing agent than a glycidyl group is disclosed in JP-A-61-197621.
JP-A No. 4-083739, an aliphatic epoxy resin represented by the general formula (III) described in Japanese Patent Application No. 4-083739, and an aliphatic epoxy resin represented by the general formula (III) described in Japanese Patent Application No. 4-083739. There is an epoxy resin represented by (IV).

[0014]

Embedded image ・ ・ ・ ・ ・ (II)

Embedded image ..... (III)

Embedded image ..... (IV) The ratio of the epoxy resin (A) having a glycidyl group and the polyvalent epoxy resin (B) having at least one epoxy group having a lower reactivity with the curing agent than the glycidyl group is as follows. , (A) is 95 to 50 parts by weight, preferably 70 to 50 parts by weight, and (B) is 5 to 50 parts by weight.
Parts by weight, preferably 30 to 50 parts by weight.

In order to improve the reliability of the semiconductor device, it is desirable to increase the amount of the epoxy resin (B). However, if the amount of the epoxy resin (B) is increased, the water absorption of the sealing agent is increased. Therefore, it is preferable to use as much (B) as possible within the allowable range of the water absorption of the sealant.

When the amount of the epoxy resin (B) is 5 parts by weight or less, that is, the amount of the epoxy resin (A) is 95 parts by weight or more, the effect of improving the reliability is small, and the epoxy resin (B)
Is at least 50 parts by weight, that is, the epoxy resin (A) is 5 parts by weight.
If the amount is less than 0 parts by weight, the water absorption of the sealant becomes high, and cracks are easily generated during solder immersion.

As the curing agent, one corresponding to the epoxy resin is used. For example, an amine-based curing agent, an acid anhydride-based curing agent, and a phenol-based curing agent can be used.
Among them, a phenolic curing agent is desirable in terms of moldability and moisture resistance of the composition.

As the phenol-based curing agent, specifically, a phenol novolak resin, a cresol novolak resin, a naphthalene type resin, and a triphenol alkane type resin can be used. Here, the amount of the curing agent is not particularly limited, but when a phenol novolak type curing agent is used, the molar ratio of the epoxy group in the epoxy resin to the phenolic hydroxyl group in the curing agent is 0.5 to 1. It is preferred to be in the range of 5.

Outside this range, the curability becomes insufficient,
The performance as a sealant cannot be maintained. Further, it is preferable that a curing accelerator is added to the sealing material of the present invention in order to promote a reaction between the epoxy group and the curing agent. Examples of the curing accelerator include one or two kinds of imidazole compounds, cycloamidine derivatives such as 1,8-diazabicyclo (5.4.0) undecene (DBU), phosphine derivatives such as triphenylphosphine, and tertiary amines. The above is used. The amount of the curing accelerator is not particularly limited, but is usually 0.01 to 5 parts by weight, preferably 0.2 parts by weight, based on the total amount of the epoxy resin and the phenol resin.
３3 parts by weight.

Further, in addition to the above components, a filler such as fine quartz or fine spherical silica may be added to the sealing material of the present invention, if necessary. Typical examples of the filler include crystalline silica, alumina, talc, kaolin, silicon nitride, aluminum nitride, boron nitride, glass fiber, and the like, in addition to the above substances.

In order to reduce the stress, a silicone polymer or a thermoplastic resin may be blended, and further, a coupling agent, a coloring agent, a release agent and the like may be appropriately blended. The semiconductor encapsulating material of the present invention can be obtained by kneading the above components. As a kneading method, a kneader, a roll mill, a continuous kneader or the like may be used. The semiconductor encapsulating material of the present invention is used for encapsulating semiconductor devices such as ICs and LSIs. Here, when the semiconductor device is sealed, a molding method conventionally used, for example, a transfer molding method, an injection molding method, or a casting method can be used. In this case, the molding temperature is 150 ~
It can be performed at 200 ° C.

[0022]

The reliability of the semiconductor device can be improved by encapsulating with the semiconductor device encapsulating material of the present invention obtained as described above. Even if an epoxy resin having a small amount of impurities such as is used, the same reliability as that obtained by using a highly purified epoxy resin can be obtained.

Further, the reliability of the highly purified epoxy resin can be further improved. Generally, an epoxy resin obtained by reacting phenol or a novolak resin with epichlorohydrin is used as an epoxy resin for encapsulation.However, since impurities such as chlorine are usually contained in the resin, liberated chlorine ions are used. Corrosion of internal wiring, patterns, and the like causes deterioration of functions such as a decrease in insulation properties and an increase in leak current during use, resulting in failure of the semiconductor device.

However, the semiconductor element sealing material of the present invention is:
(A) an epoxy resin having a glycidyl group and (B) a polyvalent epoxy resin having at least one epoxy group having a lower reactivity with a curing agent than the glycidyl group, so that an epoxy group having a low reactivity is contained. A part of the unreacted epoxy group remains in the semiconductor device, and the unreacted epoxy group reacts with the liberated chlorine ions, etc., to prevent corrosion of the internal wiring, patterns, etc. due to the released chlorine ions. It is considered that the occurrence of defects in the semiconductor device due to the deterioration of the function such as the decrease of the function and the increase of the leak current is reduced.

[0025]

EXAMPLES The present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, all parts are parts by weight.

Ortho-cresol novolak epoxy resins as shown in Table 1 were used as epoxy resins 1 and 2.

[0027]

[Table 1] Examples and Comparative Examples In addition to the components shown in Table 2, 550 parts of spherical silica, 10 parts of antimony trioxide, 1.5 parts of γ-glycidoxypropyltrimethoxysilane, 1.5 parts of wax E, and carbon black 1. The mixture obtained by adding 0 parts and 0.8 parts of triphenylphosphine was uniformly melt-kneaded with a hot two-roll mill to produce eight kinds of thermosetting resin compositions. [Examples 1 to 4, Comparative Examples 1 to 4] The following (a) to (c) are used for these thermosetting resin compositions.
Various characteristics of (d) were measured. Table 2 shows the results.

[0028]

[Table 2] High purity epoxy resin 1 and epoxy resin 2

Embedded image Epoxy resin 3

Embedded image Epoxy resin 4

Embedded image Epoxy resin 5

Embedded image Phenol resin 1

Embedded image (A) Spiral flow Using a mold conforming to the EMMI standard, 175 ° C, 70
It was measured under the condition of kg / cm ² .

(B) Mechanical strength (flexural strength, flexural modulus) 175 ° C., 70 kg / c according to JIS K6911
A bending rod of 10 × 100 × 4 mm was molded under the conditions of m ² and molding time of 2 minutes, and post-curing was performed at 180 ° C. for 4 hours.

(C) Glass transition temperature, expansion coefficient: 175 ° C., 70 kg / cm ² , molding time: 2 minutes
A test piece of × 4 × 15 mm was molded and post-cured at 180 ° C. for 4 hours, and the temperature was measured at a temperature of 5 ° C./min by a dilatometer.

(D) Moisture absorption after moisture absorption, solder cracking property and moisture resistance A semiconductor device for moisture resistance test for measuring corrosion of aluminum wiring under a condition of 175 ° C., 70 kg / cm ² , and a molding time of 2 minutes was formed to a thickness of 2 mm. It was sealed in a flat package and post-cured at 180 ° C. for 4 hours.

The package was left to stand in an atmosphere of 85 ° C. and 85% RH for 72 hours to perform a moisture absorption treatment. Then, the amount of moisture absorption was measured, and the package was immersed in a 260 ° C. solder bath for 10 seconds. After confirming the number of cracks generated in the package at this time, only non-defective products were allowed to stand in a saturated steam atmosphere at 120 ° C. for a predetermined time, and the defect occurrence rate was examined. (Below)

Continuation of the front page (56) References JP-A-3-94454 (JP, A) JP-A-61-197621 (JP, A) JP-A-1-167359 (JP, A) JP-A-2-298510 (JP) , A) JP-A-2-255826 (JP, A) JP-A-62-135467 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/20-59/38 H01L 23/29

Claims (6)

(57) [Claims] (A) 95 to 50 parts by weight of at least one epoxy resin having a glycidyl group selected from the group consisting of a cresol novolak type epoxy resin, a phenol novolak type epoxy resin and a biphenyl type epoxy resin; 5) 50 parts by weight of a polyvalent epoxy resin having at least one epoxy group represented by the following general formula (I) having lower reactivity with the curing agent than the glycidyl group, and (C) a curing agent A semiconductor element sealing material as a component. Embedded image 2. The semiconductor element sealing material according to claim 1, wherein (C) the curing agent is a phenolic curing agent. 3. The phenolic curing agent is at least one selected from the group consisting of a phenol novolak resin, a cresol novolak resin, a naphthalene type resin and a triphenol alkane type resin.
3. The semiconductor element sealing material according to item 1. 4. The semiconductor device obtained by encapsulating a semiconductor element has a solder crack defect rate after moisture absorption of 5% or less and a moisture resistance failure rate of 10% or less. 3. The semiconductor element sealing material according to item 1. 5. A method for sealing a semiconductor element using the semiconductor element sealing material according to claim 1. 6. A semiconductor device in which a semiconductor element is sealed using the semiconductor element sealing material according to claim 1.