JPH01215820A - Epoxy resin composition for semiconductor sealing and resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the title epoxy resin composition having decreased coefficient of linear expansion, modulus and thermal stress generation, by mixing an epoxy resin with an amino-modified silicone polymer of a specified MW. CONSTITUTION:The title composition is obtained by mixing 100pts.wt. epoxy resin (e.g., o-cresol novolac epoxy resin) with 5-20pts.wt. amino-modified silicone polymer of an MW >=100. This composition is useful for sealing semiconductor elements of a resin-sealed semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition for encapsulating semiconductors that has a small coefficient of linear expansion, a small modulus of elasticity, and generates little thermal stress, and a resin-sealed semiconductor device.

[Conventional technology]

In order to reduce the thermal stress of an epoxy resin composition for semiconductor encapsulation, there are two methods: adding a filler with a small coefficient of linear expansion to reduce the coefficient of linear expansion, and a method as described in JP-A-61-4721. A known method is to reduce the elastic modulus by adding a rubber component. However, in order to reduce the coefficient of linear expansion, it is filled.

As the amount of filler added increases, a problem arises in that the modulus of elasticity increases, and there is also a limit to the amount of filler added. In addition, although it is possible to reduce the elastic modulus by adding a rubber component as in the latter case, there is no method to simultaneously reduce the coefficient of linear expansion, and this is still insufficient as a method to reduce thermal stress. . In addition to the above, related compositions of this type include, for example, Japanese Patent Application Laid-open No. 61
-1.33223 publication etc. are mentioned.

[Problem to be solved by the invention]

Epoxy resin compositions are currently widely used for semiconductor encapsulation because they generally have excellent dielectric properties, electrical properties such as volume resistivity, and mechanical properties such as bending strength and impact strength. However, since epoxy resin is generally a hard resin,
When used to encapsulate a semiconductor device, it imparts large mechanical stress to the device. As a result, the device may not function properly, part of the device may be destroyed, cracks may occur in the passivation film formed on the surface of the device, or wiring on the device may be cut or misaligned, resulting in unreliable reliability. It causes a decline in sexual performance. In addition, as the degree of integration of semiconductor devices increases, devices become larger, wiring becomes finer, higher density, and multilayered.
With the trend towards thinner devices, the sealing resin layer is becoming thinner and thinner, making it easier for the sealing resin layer to crack due to mechanical stress. One of the causes of such mechanical stress is the difference in the coefficient of linear expansion between the semiconductor element and the sealing material and the shrinkage rate after molding. The semiconductor element is
The coefficient of linear expansion and shrinkage are very small, but molding materials show large values. The difference in linear expansion coefficient and contraction rate between the two causes large thermal stress to be applied to the semiconductor element, the encapsulating material, and other constituent materials through encapsulation, after-cure, and various subsequent thermal histories. Therefore, as the dimensions of semiconductor elements become larger and the thickness of encapsulating materials become increasingly thinner, reducing such thermal stress will become an extremely important issue in improving the reliability of semiconductors. ing.

Thermal stress applied to a semiconductor element sealed with resin is
It is determined by the following formula.

However, σ: Thermal stress k applied to the element; αr: Constant αr: Coefficient of linear expansion of the sealing material αS: Coefficient of linear expansion of the semiconductor element Tg: Glass transition temperature of the sealing material Trt: Room temperature E: Modulus of elasticity of the sealing material. Therefore, in order to reduce thermal stress, (1) lower the glass transition temperature (T, ) of the sealing material, (2) lower the linear expansion coefficient (α, ) of the sealant, and (3) seal. One possible method is to reduce the elastic modulus (E,) of the material.

However, method (1) cannot be applied to materials for encapsulating semiconductor elements because the heat resistance and moisture resistance of the semiconductor are reduced and reliability is impaired. As a method (2), a method of adding an inorganic filler with a small coefficient of linear expansion is known.
If the amount of filler added is increased in an attempt to further reduce the coefficient of linear expansion, the viscosity of the sealing material increases, reducing workability. Therefore, attempts have been made to reduce the increase in the viscosity of the sealing material by using spherical fillers, but there is a problem that increasing the amount of filler added increases the elastic modulus, and there is a limit to the amount of filler added. There is. Further, as the method (3), a method of adding a flexibility imparting agent such as a butadiene-acrylonitrile copolymer having a carboxyl group at the terminal, a silicone polymer, or a solid silicone rubber is known. In the future, as the degree of integration of semiconductor devices increases, such a reduction in the elastic modulus alone will not be sufficient to further reduce thermal stress. Therefore, in order to reduce thermal stress without reducing heat resistance, etc., we must lower the elastic modulus of the sealing material without lowering its glass transition temperature, and further reduce the difference in linear expansion coefficient between each constituent material. to do,
In other words, it is important to reduce the linear expansion coefficient of the sealing material.

An object of the present invention is to provide an epoxy resin composition particularly useful for semiconductor encapsulation, which has a glass transition temperature equivalent to that of conventional epoxy resin cured products and simultaneously reduces both the coefficient of linear expansion and the modulus of elasticity. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation that has lower thermal stress than conventional cured epoxy resin compositions, and a resin-encapsulated semiconductor device encapsulated with the epoxy resin composition.

[Means to solve the problem]

The above problem can be solved by using an epoxy resin composition for semiconductor encapsulation containing an amine-modified silicone polymer having a molecular weight of 10,000 or more in an epoxy resin, or by adding an amount of the amine-modified silicone polymer to 100% by weight of the epoxy resin. 5 to 20 parts by weight of an epoxy resin composition for semiconductor encapsulation, or a resin-encapsulated semiconductor device in which a semiconductor element is encapsulated with an epoxy resin composition, wherein the epoxy resin composition has a molecular weight of 10,000 or more. The problem is solved by a resin-encapsulated semiconductor device containing an amine-modified silicone polymer.

〔Example〕

Hereinafter, the content and one embodiment of the present invention will be explained with reference to FIGS. 1 to 3.

It seems possible to reduce the thermal stress of an epoxy resin composition useful for semiconductors if both the coefficient of linear expansion and modulus of elasticity of the resin itself can be reduced at the same time. Therefore, the present inventors investigated the relationship between various physical properties of cured products when modifiers of various molecular weights were added to epoxy resins for semiconductor encapsulation.

As a result, by adding silicone polymers with various functional groups to epoxy resin, the linear expansion coefficient and elastic modulus of the cured product change greatly. It was found that the expansion coefficient was a small value.

As the silicone polymer having a functional group, polydimethylsiloxane having an amine group, carboxyl group, epoxy group, hydroxyl group, etc. as a functional group can be used. Among them, polydimethylsiloxane having an amino group has a large decrease in linear expansion coefficient and elastic modulus, and can greatly reduce thermal stress.

Furthermore, the molecular weight of the amine-modified silicone polymer is preferably 10,000 or more, and when a silicone polymer with a molecular weight smaller than 10,000 is added, the elastic modulus of the cured product is small, but the linear expansion coefficient is lower than that of the silicone polymer added. The value is larger than that without, making it impossible to significantly reduce thermal stress. If a silicone polymer with a molecular weight smaller than 10,000 is added, there will be mold stains during molding and problems with curability.
As a silicone polymer, thermal deterioration is severe due to poor adhesion with 1-Rix resin, and the effect of low stress is small.

In addition, in order to reduce stress, it is extremely effective to reduce the difference in linear expansion coefficient between each component material, and the gold wire (linear expansion coefficient 1. In order to obtain a linear expansion coefficient of 4×10-5/°C or less, the molecular weight of the modifier to be added should be 1000
0 or more is desirable.

These silicone polymers can be added in an amount of 2 to 40 parts by weight based on 0 parts by weight of the epoxy resin.
In particular, it is preferable to add 5 to 20 parts by weight in order to obtain good heat resistance, moisture resistance, and mechanical properties. Furthermore, these silicone polymers can be blended simultaneously with other materials, and can also be used after preliminarily reacting with epoxy resins, curing agents, and the like.

Epoxy resins include cresol novolac type epoxy resins, phenol novolac type epoxy resins, bisphenol A type epoxy resins, etc., which are currently commonly used as molding materials for semiconductor encapsulation, and novolac resins such as phenol novolacs and cresol novolacs as curing agents. ,
It is a composition using an acid anhydride such as anhydrous pyromellitic acid or anhydrous benzophenone, and further containing a curing accelerator, a filler, a coupling agent, a coloring agent, a flame retardant, a mold release agent, etc. This epoxy resin composition can be produced in exactly the same manner as conventional molding materials for semiconductor encapsulation, and can also be encapsulated in semiconductors in exactly the same manner. That is, each material is kneaded using a twin-screw roll or extruder heated to 70-100'C, and then kneaded using a transfer press at a mold temperature of 160-190°C and a molding pressure of 30-100 kg-C.
Il+-2, it can be molded in a curing time of 30 seconds to 3 minutes.

By adding an amine-modified silicone polymer with a molecular weight of 10,000 or more to the epoxy resin as a modifier, both the linear expansion coefficient and elastic modulus of the cured product can be simultaneously reduced, and the linear expansion coefficient between each constituent material of the semiconductor device can be reduced. The difference can be reduced. Here, the amine-modified silicone polymer interacts with the 71-helix resin to change the curing state of the resin, resulting in a smaller linear expansion coefficient, and at the same time exists as a soft rubber-like elastic body in the 7-helix resin. Therefore, the elastic modulus of the cured product becomes small.

Therefore, it is possible to reduce the thermal stress caused by sealing, after-curing, or various subsequent thermal histories, and improve the reliability of temperature cycle resistance, heat resistance, and moisture resistance.

Examples 1 to 5 and Comparative Examples 1 to 4 Using various silicone polymers shown in Table 1 as modification materials, an epoxy resin composition having the composition shown in Table 2 was heated at about 80°
The mixture was mixed for about 10 minutes using a twin-screw roll heated to C.

Table 1 Transfer forming using the obtained composition, 180°
C/After curing for 6 hours, the linear expansion coefficient, flexural modulus, and glass transition temperature were measured. The result is the first
This will be explained with reference to FIG.

Figure 1 shows the relationship between the functional group equivalent of the modifier and the flexural modulus of the molded product when 10 parts by weight of various modifiers are added to the resin composition. A modifying agent having an amino group (A-D in Table 1) + Prone I- marked with Δ is a modifying agent having an epoxy group as a functional group (A-D in Table 1)
E and F in the table and the plots in the original print are the characteristics of the composition (molded article) using a modifier having a hydroxyl group as a functional group (G and H in Table 1). Note that this plotting method is the same for FIGS. 2 and 3 described below. As shown in FIG. 1, it was found that the addition of a silicone polymer resulted in a smaller value than the system without the addition. FIG. 2 is a diagram showing the relationship between the functional group equivalent of the modified material and the linear expansion coefficient of the molded article when 10 parts by weight of various modifying agents are added to the resin composition. As shown in FIG. 2, the molecular weight of the silicone polymer added is 4. OO0
Above that, the linear expansion coefficient becomes smaller than that of a system without silicone polymer, and a silicone polymer with a molecular weight of 10,000 or more has a linear expansion coefficient of 1.4
It was found that the value is smaller than l 0-5/'C.

In addition, Fig. 3 is a diagram showing the relationship between the functional group equivalent of the modifier and the glass transition temperature of the molded product when 10 parts by weight of various modifiers are added to the resin composition. It can be seen that even when these silicone polymers are added, the glass transition temperature of the cured product hardly changes.

Therefore, as a modifier that is highly effective in reducing stress, it is effective to use a modifier that reduces both the elastic modulus and linear expansion coefficient of the cured product, and such modifiers have a molecular weight of 1. OO
It has been found that amine-modified silicone polymers having a molecular weight of O0 or more are particularly effective in reducing stress.

Furthermore, using these resin compositions, a semiconductor element having aluminum zigzag wiring on the surface was sealed, and -5
5°C/30 min Hl 50'C/30
The crack resistance of the sealing layer and the connection reliability between leads, gold wires, and aluminum wiring in m1n thermal cycle tests (
A case where the resistance value changed by 50% or more was determined to be defective).

Table 3 shows the results of the crack resistance test, and Table 4 shows the results of the connection reliability test. The numbers in Tables 3 and 4 represent the defect rate, where the denominator is the total number of tests and the numerator is the number of defective tests.

Table 3 Table 4 As a result, semiconductor devices encapsulated using resin compositions with low elastic modulus and linear expansion coefficient have poor crack resistance when subjected to thermal shock such as thermal cycle tests, and poor wiring performance. It was found that the connection reliability was extremely high.

〔Effect of the invention〕

According to the present invention, the epoxy resin has a molecular weight of 100.

By containing the above amine-modified silicone polymer, both the linear expansion coefficient and elastic modulus of the epoxy resin composition for semiconductor encapsulation become small. In addition, a resin-sealed semiconductor device in which a semiconductor element is encapsulated using this epoxy resin composition for semiconductor encapsulation has a reduced thermal stress caused by the difference in linear expansion coefficient of each constituent material, resulting in damage to the semiconductor element and damage to wiring. This has the excellent effect of preventing cutting, misalignment, cracking of the sealing layer, etc., and improving the reliability of the resin-sealed semiconductor device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the functional group equivalents of various modifiers and the flexural modulus of a molded article in a resin composition according to an example of the present invention;
Figure 2 shows the relationship between the functional group equivalent of the modifier and the linear expansion coefficient of the molded product, and Figure 3 shows the relationship between the functional group equivalent of the modifier and the glass transition temperature of the molded product. It is a diagram. Agent Patent attorney Katsuma Ogawa: Self, -, Pa'

Claims (1)

[Scope of Claims] 1. An epoxy resin composition for semiconductor encapsulation, characterized in that the epoxy resin contains an amine-modified silicone polymer having a molecular weight of 10,000 or more. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the amount of the amine-modified silicone polymer added is 5 to 20 parts by weight per 100 parts by weight of the epoxy resin. 3. A resin-encapsulated semiconductor device in which a semiconductor element is sealed with an epoxy resin composition, wherein the epoxy resin composition contains an amine-modified silicone polymer having a molecular weight of 10,000 or more. .