JP2529845B2 - Mullite substrate - Google Patents

Description

The present invention relates to a semiconductor element housing package for housing a semiconductor integrated circuit element such as an LSI or an insulating substrate such as a multilayer wiring board on which the semiconductor integrated circuit element is mounted. The present invention relates to a mullite substrate used.

[Conventional technology]

Conventionally, a package that houses a semiconductor integrated circuit device such as an LSI or a multilayer wiring board on which the semiconductor integrated circuit device is mounted uses alumina (Al ₂ O ₃ ) having excellent electrical insulation as a base, and tungsten is used on the surface. It is manufactured by providing electrical wiring made of metal such as (W), molybdenum (Mo), manganese (Mn).

However, in a package or the like using this alumina as a base, the propagation speed of the signal transmitted through the electric wiring is slow due to the high dielectric constant of alumina constituting the base, which is 9 to 10 (room temperature 1 MNz). In the semiconductor integrated circuit device in which the signal propagation speed has been increased, there is a drawback that it cannot be housed or mounted in a package using alumina as a base, a multilayer wiring board, or the like.

In addition, the shape of the element itself has become larger with the recent higher density and higher integration of the semiconductor integrated circuit element. When the semiconductor integrated circuit element is mounted on the conventional package or the multilayer wiring board, the semiconductor integrated circuit element is Since the thermal expansion coefficients of the circuit element and the package etc. are largely different, the package etc. expands greatly as compared with the semiconductor integrated circuit element when heat is applied during mounting to the both, and as a result, the semiconductor integrated circuit There are problems that the element is damaged or peeled off from the package, the multilayer wiring board, or the like.

Therefore, the thermal expansion coefficient of silicon constituting a semiconductor integrated circuit element is 3.0 to 3.5 × 10 ⁻⁶ / ° C. in order to solve the drawbacks such as the package using the conventional alumina as a base.
Thermal expansion coefficient of 4.0-4.5 × 10, which is almost the same as (room temperature to 400 ℃)
^The use of mullite, which has ^-6 / ℃ (room temperature to 400 ℃) and a low dielectric constant of 7.0 to 7.4 (room temperature, 1MHz), is under consideration as a substrate for semiconductor device housing packages and multilayer wiring boards.

However, since mullite is more difficult to sinter than alumina, the resulting sintered body has a small relative density of about 85% relative to the theoretical density and has a large number of pores. When the body is used as a substrate for a package or a multilayer wiring board, and its surface is provided with electrical wiring,
The electric wiring has a drawback that it is broken due to the existence of the pores. In addition, since the mullite sintered body has a large number of pores, the heat dissipation is poor, and therefore the heat generated by the mounted semiconductor integrated circuit device cannot be satisfactorily released to the atmosphere, and the semiconductor integrated circuit device However, there is also a defect that the element peels off from the package or the multilayer wiring board due to the thermal history of heat generated by the element itself.

[Object of the Invention]

The present invention has been devised in view of the above-mentioned drawbacks, and its object is suitable as a base for a package or a multilayer wiring board for accommodating and mounting a semiconductor integrated circuit device, which is highly integrated, large-sized, and has a high signal propagation speed. The present invention is to provide a mullite substrate used in.

[Means for solving problems]

The mullite substrate of the present invention contains 70 to 95% by weight of mullite,
The total amount of at least one of MgO and CaO and SiO ₂ is 5 to 30% by weight, and SiO ₂ , MgO and CaO are surrounded by the following points A, B and C in FIG. In addition, it is characterized in that it is within the range excluding point A.

However, X, Y, and Z represent the weight% of SiO ₂ , MgO, and CaO, respectively, and satisfy X + Y + Z = 100.

That is, the present invention relates to mullite (3Al ₂ O ₃ .2SiO _{2 to} 2Al ₂ O).
₃ · SiO ₂₎ crystalline phase and SiO _2, MgO, is constituted by a vitreous grain boundary layer of a CaO, mullite and these SiO _2, MgO, not rise to the solid phase reaction between the CaO, in the sintered body It has a coefficient of thermal expansion that is almost the same as that of silicon that constitutes semiconductor integrated circuit elements by not containing a crystalline phase other than mullite, and it does not impair the original characteristics of mullite, which has a low dielectric constant, and it has a high relative density and pores. In this case, the semiconductor integrated circuit device can be suitably used as a package for accommodating and mounting a semiconductor integrated circuit device or a base body of a multilayer wiring board.

In the present invention, when the amount of mullite exceeds 95% by weight, the sinterability is lowered and a dense sintered body cannot be obtained.
If it is less than 10% by weight, the amount of glass produced increases and pores tend to remain, and in either case, it becomes unsuitable for use as a substrate for a package for housing a semiconductor element, a multilayer wiring board, or the like.

On the other hand, SiO ₂ , MgO, and CaO that make up the glassy grain boundary layer are the first
If only SiO ₂ shown by point A in the figure is added to mullite, the sintered body will not be dense and will have many pores, and the sintering temperature will be extremely high. When the amount of SiO ₂ is BC line shown in FIG. 1, that is, less than 60% by weight, 3Al ₂ O ₃ · 2SiO ₂ + CaO → Al ₂ O ₃ · CaO.
Like 2SiO ₂ + 2Al ₂ O ₃ , a part of mullite solid-phase reacts with CaO to produce anorthite (Al ₂ O ₃ · CaO · 2SiO ₂ ) and alumina. As a result, the generated alumina is a sintered body. The coefficient of thermal expansion is increased, and the coefficient of thermal expansion of the mullite sintered body greatly differs from the coefficient of thermal expansion of silicon that constitutes the semiconductor integrated circuit element. In either case, a package for accommodating semiconductor elements, a multilayer wiring board, etc. Unsuitable for use as a substrate.

〔Example〕

 Next, the present invention will be described based on examples.

Al ₂ O ₃ 76 wt%, were weighed mullite powder and SiO ₂ having the composition of SiO ₂ 24% by weight, MgO and CaO to respective concentrations with the composition shown in Table 1, a vibration mill together with an organic solvent and alumina balls The raw material slurry was adjusted by pulverizing and mixing. Then, after the raw material slurry is dried and solidified, a binder such as wax, a dispersant and an organic solvent are added and mixed. After that, dry again to 100 mesh
The raw material powder for press molding is sized by passing.

The powder thus obtained is compacted at a pressure of 800 to 1200 Kg / cm ² , and the powder is calcined in the atmosphere at a calcination temperature in the range of 1400 to 1900 ° C.
It was fired for a time to obtain a mullite sintered body.

Next, using a disc-shaped mullite sintered body with a diameter of 20 mm and a thickness of 2 mm after firing, the relative density and the identification of the crystal phase by the X-ray diffraction method were performed. Similarly, a disc-shaped mullite with a diameter of 50 mm and a thickness of 1.5 mm was used. Dielectric constant (room temperature, 1MHz) was measured using a sintered body, and thermal expansion coefficient (room temperature to 400 ° C) was measured using a polished 15 mm long, 5 mm square prismatic mullite sintered body. . The results are shown in Table 1.

As is clear from Table 1, Sample Nos. 1 and 59 are cases in which the amount of mullite is less than 70% by weight or more than 95% by weight, and the relative density is low at 87% or less. Further, as shown in sample numbers 20, 30, and 58, when only SiO ₂ was added to mullite, cristobalite was generated as a crystal phase in addition to mullite, and the relative density was extremely low at 83% or less. Also, sample numbers ₂ , ₃ , ₄ , 21, 22, 23, 40, 41, 42 are SiO ₂ , MgO and C.
When aO is out of the range surrounded by the points A, B, and C shown in Fig. 1, spinel or alumina and anorthite other than mullite are generated as the crystal phase, and the thermal expansion coefficient is 4.9 × 10 ^-6 / ℃
The above results are large, and none of them retains the original characteristics of mullite.

In contrast, the mullite substrate of the present invention has a relative density of 91
% Or higher, and the thermal expansion coefficient is sufficiently low at 4.5 × 10 ⁻⁶ / ° C. or lower, and the dielectric constant is also low at 7.1 or lower. Above all, SiO ₂ , MgO
And CaO within the range surrounded by points A, D and E shown in Fig. 1 (Sample Nos. 11 to 19, 30 to 38, 49 to 57) have a thermal expansion coefficient of 4.3 × 10 ^-6 / ° C. Below, A shown in Fig. 1
Within the range enclosed by the F and G points (Sample Nos. 16 to 19,
35 to 38, 54 to 57) have a thermal expansion coefficient of 4.2 × 10 ⁻⁶ / ° C. or less and a dielectric constant of 6.9 or less.

〔The invention's effect〕

Since the mullite substrate of the present invention is dense and has a thermal expansion coefficient almost equal to that of silicon constituting the semiconductor integrated circuit device, as is apparent from the above-mentioned embodiment, the mullite substrate contains the semiconductor integrated circuit device, When used as a base for a package for storing semiconductor elements to be mounted, a multilayer wiring board, etc., the electric wiring provided on the surface will not be broken, and the semiconductor integrated circuit element will not be damaged or peeled off. Furthermore, since the permittivity is sufficiently low, it is possible to increase the propagation speed of the signal transmitted to the electric wiring, and it is possible to store and mount the semiconductor integrated circuit device of recent years in which the signal propagation speed is increasing. .

[Brief description of drawings]

FIG. 1 is a ternary diagram showing the vitreous grain boundary layer in the mullite substrate of the present invention.

Claims (1)

(57) [Claims] 1. A mullite is 70 to 95% by weight, and the total amount of at least one of magnesia (MgO) and calcia (CaO) and silica (SiO ₂ ) is 5 to 30% by weight.
In FIG. 1, a mullite substrate characterized in that SiO ₂ , MgO and CaO are surrounded by points A, B and C below and are in a range excluding point A. However, X, Y, and Z represent the weight% of SiO ₂ , MgO, and CaO, respectively, and satisfy X + Y + Z = 100. X Y Z A 100 0 B 60 40 0 C 60 0 40