JP3014856B2 - 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 semiconductor device having excellent reliability.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as transistors, ICs, and LSIs are sealed in ceramic packages or the like to form semiconductor devices. Recently, however, plastic packages have been used from the viewpoint of cost and mass productivity. Resin sealing has become mainstream. Epoxy resins have conventionally been used for this type of resin sealing, and have achieved good results. However, due to technological innovation in the field of semiconductors, the degree of integration has been increased, the element size has been increased, and the wiring has become finer, and the packages have also become smaller and thinner. Higher reliability (moisture resistance reliability, heat resistance reliability, etc. of the resulting semiconductor device)
There is a demand for improvement. In particular, in recent years, the chip size has become increasingly larger, and a thermal cycle test (hereinafter referred to as “T”), which is an accelerated test for evaluating the performance of a resin for semiconductor encapsulation, has been conducted.
A higher performance is required for “CT test”. In addition, surface mounting has become the mainstream as a semiconductor mounting method. For this reason, even if a semiconductor package is absorbed in moisture and then immersed in a solder bath, it is required that the package does not crack or swell. . In this regard, conventionally, it has been studied to reduce the thermal stress by modifying with rubber in order to improve each property expressed by the TCT test, but in fact, a sufficient effect has not yet been obtained. is there.

[0003]

As described above, the conventional epoxy resin compositions for encapsulation have not had sufficient properties such as the results of TCT tests and crack resistance during solder immersion. For this reason, there is a strong demand for improvement of both of the above characteristics so as to be able to cope with an increase in the element size and surface mounting due to the above technical innovation.

The present invention has been made in view of such circumstances, and has as its object to provide a semiconductor device having excellent characteristics evaluated by a TCT test.

[0005]

In order to achieve the above object, a semiconductor device according to the present invention comprises a semiconductor element and a sealing resin layer for sealing the semiconductor element, wherein the sealing resin layer has a fracture toughness. The ratio (Kc / σ) of the value (Kc) and the internal stress value (σ) obtained from the elasticity value and the linear expansion coefficient is set to 2.0 or more.

[0006]

As methods for preventing the occurrence of package cracks during the TCT test, there are two methods for reducing the thermal stress generated inside the package and improving the fracture toughness value of the sealing resin itself. According to the present invention, as a result of the present inventors' evaluation by the TCT test, the factors related to the above are related to the elastic modulus of the cured epoxy resin composition and the internal stress value (σ) obtained from the linear expansion coefficient. The factor (Kc / σ) with respect to the fracture toughness value (Kc) of the cured epoxy resin composition is 2.
This is based on the finding that when the value is set to 0 or more, cracks generated in the package when the semiconductor device is subjected to the TCT test are drastically reduced.

Next, the present invention will be described in detail.

In a semiconductor device according to the present invention, the semiconductor element comprises:
The resin is sealed with a special thermosetting resin composition cured body that is a sealing resin layer.

The above-mentioned special thermosetting resin composition cured product is
Although the components and the production method are not particularly limited, they can be obtained, for example, by curing a resin composition mainly composed of an epoxy resin generally used as a resin for semiconductor encapsulation.

The epoxy resin composition comprises an epoxy resin (component A), a curing agent (component B), and an inorganic filler (C
Component) and is usually in the form of a powder or a tablet thereof.

The epoxy resin (component A) is not particularly limited, and includes various epoxy resins conventionally used as sealing resins for semiconductor devices, such as cresol novolak type, phenol novolak type and bisphenol A type. Can be Among these epoxy resins, the melting point is higher than room temperature, and the use of those having a solid state or a high-viscosity solution at room temperature gives a good result. The novolak type epoxy resin usually has an epoxy equivalent of 160 to 250 g / eq and a softening point of 50 to 11.
The one at 0 ° C. is generally used.

Preferable examples of the curing agent (component B) used together with the epoxy resin (component A) include phenol resins such as phenol novolak and cresol novolak. These novolak resins have a softening point of 50 to
It is preferable to use one having a temperature of 110 ° C. and a hydroxyl equivalent of 70 to 150 g / eq. In particular, the use of cresol novolak among the above novolak resins gives good results.

The epoxy resin (A component) and the curing agent (B
Component) with the epoxy group 1 in the epoxy resin.
It is preferable that the hydroxyl group in the curing agent is set to 0.8 to 1.2 equivalents with respect to the equivalents.

An inorganic filler (component C) used together with the epoxy resin (component A) and the curing agent (component B)
The particle size is not particularly limited, and may be a conventionally known one.
It is preferable to use m. The content of such an inorganic filler (component C) is 7% of the entire epoxy resin composition.
It is preferably set to 0% by weight (hereinafter abbreviated as “%”) or more. Particularly preferred is 78% or more. That is,
If the content of the inorganic filler is less than 70%, the effect of improving various properties tends to be significantly reduced.

The epoxy resin composition used in the present invention may contain, if necessary, other additives, such as tertiary amines and quaternary ammonium salts which are conventionally known as curing accelerators, in addition to the above-mentioned components A to C. , Imidazoles and boron compounds can be used alone or in combination. Further, flame retardants such as antimony trioxide and phosphorus compounds, and coupling agents such as pigments and silane coupling agents can be used.

The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, after appropriately mixing the components A to C and other additives as necessary, the mixture is melted and kneaded in a kneading machine such as a mixing roll machine in a heated state, and then cooled to room temperature. Next, the epoxy resin composition can be manufactured by a series of steps of pulverizing by a known means and tableting as necessary.

The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding. At this time, the curing conditions are set so that the ratio (Kc / σ) between the fracture toughness value (Kc) and the internal stress value (σ) of the obtained cured cured product is 2.0 or more.

In the thus obtained thermosetting resin composition which is a sealing resin layer of a semiconductor device, the fracture toughness value (Kc) of the cured epoxy resin composition is as follows:
It is necessary to set the ratio (Kc / σ) between the elastic modulus (E) and the internal stress value (σ) obtained from the coefficient of linear expansion (α) to 2.0 or more. That is, by setting Kc / σ to 2.0 or more, it is possible to obtain excellent characteristics evaluated by the TCT test.

The fracture toughness value (Kc) of the cured epoxy resin composition can be determined by conducting a fracture toughness test in accordance with ASTME399-81.

The elastic modulus (E) of the cured epoxy resin composition is determined by measuring viscoelasticity. Further, the linear expansion coefficient (α) is obtained by a thermal analysis measurement device (TMA). The internal stress value (σ) is calculated by the following equation using the elastic modulus (E) and the coefficient of linear expansion (α).

[0021]

(Equation 1)

[0022]

As described above, in the semiconductor device of the present invention, the sealing resin layer for sealing the semiconductor element has a fracture toughness (Kc) and an elastic modulus (E) of the cured epoxy resin composition. (Kc / σ) is set to 2.0 or more with respect to the internal stress value (σ) obtained from the coefficient of linear expansion (α). Therefore, the characteristics evaluated by the TCT test are improved, and the life is extended.

Next, examples will be described together with comparative examples.

[0024]

Examples 1 to 5, Comparative Examples 1 and 2 The components shown in Table 1 below were blended in the proportions shown in the table, and were melted and kneaded with a mixing roll machine (temperature: 100 ° C.) for 3 minutes. After solidification, the mixture was pulverized to obtain a desired finely powdered epoxy resin composition.

[0025]

[Table 1]

Using the fine powdered epoxy resin composition obtained by the above Examples and Comparative Examples,
By transfer molding at 75 ° C., a semiconductor device having a cured sealing body having a Kc / σ of 2.1 to 2.8 was obtained. This package is 80 pink wad flat package (8
(0 pin QFP), the size is 20 mm × 14 mm × 2 mm in thickness, and the die pad size is 8 × 8 mm.
The semiconductor device thus obtained was subjected to -65 ° C
The TCT test was performed by changing the number of cycles from / 5 minutes to 150 ° C./5 minutes to 500, 1000, and 1500 cycles. Then, the number of occurrences of package cracks in the TCT test was measured. The results are shown in Tables 2 and 3 below.

A cured product was prepared from the obtained finely divided epoxy resin composition under the same conditions as in the transfer molding. Next, the internal stress value (σ) of the cured product
And the fracture toughness value (Kc) were measured and calculated by the method described above, respectively. Then, the ratio (Kc /
σ) was calculated, and the results are shown in Tables 2 and 3 below.

[0028]

[Table 2]

[0029]

[Table 3]

From the results in Tables 2 and 3, the product of the example has a better result of the crack resistance test in the TCT test than the product of the comparative example. From this, it can be seen that the example product has significantly improved reliability.

────────────────────────────────────────────────── (5) References JP-A-61-99356 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/29 C08G 59/18 H01L 23 / 31

Claims (1)

(57) [Claims] 1. A semiconductor device comprising: a semiconductor element; and a sealing resin layer for sealing the semiconductor element, wherein the sealing resin layer has a fracture toughness value (Kc).
And a ratio (Kc / σ) between the elasticity value and the internal stress value (σ) obtained from the coefficient of linear expansion is set to 2.0 or more.