JPH06176963A - Alumina ceramics laminate - Google Patents

Abstract

PURPOSE:To increase an apparant specific dielectric constant and hence reduce the number of layers of a dielectric by dispersing metal rhenium excellent in a sintering property and high temperature stability in a ceramics substrate chiefly containing alumina. CONSTITUTION:An alumina ceramics laminate 11 is adapted such that there is disposed between upper and lower insulators 12 a capacitor layer 15 composed of a high dielectric layer 13 and electrode layers 14 formed on the upper and lower surfaces of the high dielectric layer 13. The high dielectric layer 13 is formed with alumina and dispersed metal rhenium. Hereby, a specific dielectric constant is raised to reduce the number of laminate layers and miniaturize the capacitor through the dispersion of the metal rhenium. Further, the yield is raised and the cost is reduced. Additionally, there is no possibility of shortcircuiting, so that there are ensured higher reliability and excellent frequency characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alumina ceramics laminated body, and more particularly to an IC package and a circuit in which a large-capacity capacitor needs to be built-in in order to cope with an increase in the speed of an LSI to be mounted (an increase in operating frequency). The present invention relates to an alumina ceramic laminate used for substrates, electronic components, etc. (hereinafter, these components are collectively referred to as a package).

[0002]

2. Description of the Related Art In recent years, with the speeding up of LSIs mounted (speeding up of operating frequency), it has become necessary to provide a decoupling capacitor in a package in order to effectively remove noise.

Conventionally, to provide such a decoupling capacitor, there are a case where the capacitor is attached to the outside of the package and a case where the capacitor is formed inside the package. First, when the capacitor is attached to the outside of the package, the wiring for attaching the capacitor is routed inside the package, and the wiring is drawn to the outside to attach the capacitor.

When a capacitor is formed inside a package, a ceramic base material composed of alumina and a sintering aid is used as a dielectric layer, and electrode layers are formed on the upper and lower surfaces of the dielectric layer. A layer was formed, and an insulating layer made of alumina ceramics having the same composition as that of the dielectric layer was further laminated on and under the capacitor layer. However, when a large-capacity capacitor is required, it is necessary to increase the number of capacitor layers or reduce the distance between electrodes. It is also known that an alumina wiring substrate body using tungsten as a wiring material is provided with a built-in capacitor formed of an aggregate in which tungsten particles are dispersed in an alumina layer (Japanese Patent Laid-Open No. 59-108397). .

[0005]

When a capacitor is connected to the outside of the package and attached, the wiring for attaching the capacitor to the outside is routed inside the package, which complicates the inside and increases the reactance of the package. There was a problem that it became unfavorable. Further, when the operating frequency of the LSI is increased to several hundred MHz or more, it is difficult to obtain a small capacitor having a large capacity that can cope with this high frequency region, and it becomes necessary to attach a large capacitor, resulting in a large package. There were challenges.

When a capacitor is formed inside the package, a ceramic base material composed of alumina and a sintering aid is used as a dielectric. However, since the dielectric constant of alumina is low, a large capacity capacitor is required. In this case, it is necessary to increase the number of capacitor layers or reduce the distance between electrodes. However, increasing the number of layers in the capacitor increases the thickness and size of the laminated body, and the increase in the process causes the problem of lowering the yield and increasing the cost.In addition, reducing the distance between the electrodes increases the possibility of short circuit. Therefore, there was a problem that reliability was lowered.

Further, in the case of the one disclosed in the above-mentioned Japanese Patent Laid-Open No. 59-108397, the cost is high because the alumina is sputtered on the tungsten particles and the paste is prepared thereafter, and the capacitor layer is used when a large capacity capacitor is required. There is a limit to reducing the distance between the electrodes by thinning the tungsten particles because the tungsten particles are as large as 1.8 μm. Further, if the tungsten particles are not sufficiently covered with alumina, a short circuit occurs between the opposing electrodes. There was a problem of high possibility.

The present invention has been invented in view of the above problems, is small in size, has a high yield, is low in cost, and is highly reliable because it is difficult to short-circuit, and is excellent in frequency characteristics. It is an object of the present invention to provide an alumina ceramics laminated body incorporating a high dielectric constant layer.

[0009]

In order to achieve the above object, the alumina ceramics laminate according to the present invention is characterized by having a high dielectric constant layer mainly composed of alumina and metallic rhenium dispersed therein.

[0010]

[Function] By dispersing metallic rhenium, which has good sinterability and stability at high temperature, in the ceramics base material mainly composed of alumina, the apparent relative dielectric constant becomes high, and conventional rhenium that does not disperse metallic rhenium The relative permittivity of the built-in capacitor can be approximately doubled as compared with the laminated body. Therefore, it is possible to reduce the number of dielectric layers to about half. Also, if there is an appropriate amount, there is no possibility of short circuit,
No decrease in the relative dielectric constant was observed even at 1 GHz, and an alumina ceramics laminate having a sufficiently high dielectric constant layer was formed.

[0011]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the alumina ceramic laminate according to the present invention will be described below.

FIG. 1 is a schematic sectional view showing an alumina ceramics laminated body in an example. In the figure, reference numeral 11 denotes an alumina ceramics laminated body 11, and the alumina ceramics laminated body 11 has, as shown in FIG. 1, a high dielectric constant layer 13 and this high dielectric constant layer between upper and lower insulating layers 12. A capacitor layer 15 including electrode layers 14 formed on the upper and lower surfaces of 13 is disposed and formed, and this high dielectric constant layer 13 is composed of alumina and dispersed metal rhenium.

Alumina ceramics laminate 1 of this embodiment
1 is manufactured as follows. First, rhenium metal is added at various ratios shown in Table 1 below to a ceramic substrate made of alumina and a sintering aid. A binder, a plasticizer and a solvent are mixed with this to make a slurry, and a green sheet having a thickness of about 60 μm is formed by a tape molding method. Next, W (tungsten) electrodes are printed on both surfaces of the green sheet to form the electrode layer 14. Then, a normal 600 μm thick alumina green sheet is laminated on the upper and lower sides of the electrode layer 14 and integrally fired in a reducing atmosphere mainly containing nitrogen and hydrogen at a temperature range of 1500 to 1600 ° C. for 2 hours. Then, the alumina ceramic laminate 11 is manufactured. In the figure, 16 is a through hole,
Reference numeral 17 indicates a pad portion.

Table 1 below also shows the measurement results of the characteristics of the capacitor layer 15 of the alumina ceramics laminated body 11 by the above manufacturing method. The relative permittivity in Table 1 is a value calculated from the capacitance measured at 1 kHz, 1 MHz, and 1 GHz, the electrode area, and the distance between the electrodes. The insulation resistance is a resistance value calculated from a current value 1 minute after applying DC 100V. In addition,
All values in Table 1 are 50 μm after firing.
m, area 50 □.

[0015]

[Table 1]

As can be seen from Table 1, in Example 1 in which 0.5 part by weight of metallic rhenium was added, it was slightly better than Comparative Example 1 of the prior art in which nothing was added, but there was little change. No, the effect of addition was not sufficient. However, in Example 3 in which 1 part by weight of metal rhenium was added, the relative permittivity could be increased by 50%, and no decrease in relative permittivity was observed even at 1 GHz. Further, the addition ratio is 20 parts by weight, 30 parts by weight, 40 parts by weight.
When the weight ratio was changed to 50 parts by weight, the relative dielectric constant could be increased by 80% as compared with the comparative example, and in this case as well, a sufficient relative dielectric constant could be obtained at 1 GHz. However, in Example 13 in which 58 parts by weight was added, there was a short circuit, so that a sufficient dielectric constant was obtained even at 1 GHz and there was no possibility of short circuiting.
It is understood that it is desirable to add the metal rhenium in an amount of 1 to 50 parts by weight in order to form

Further, even if rhenium oxide (Re ₂ O ₇ ) is added, the same effect as when metal rhenium is added can be obtained. Rhenium oxide is an alumina ceramic laminate 11
Is reduced to rhenium metal in the process of firing. Table 2 below shows a case where an experiment was conducted by replacing the metallic rhenium in Table 1 with rhenium oxide.

[0018]

[Table 2]

As is clear from Table 2, in Example 16 in which 0.5 part by weight of rhenium oxide was added, it was slightly better than Comparative Example 1 of the prior art in which nothing was added, but the change was not so great. However, the effect of addition was not sufficient.
However, in Example 18 in which 1 part by weight of rhenium oxide was added, the relative dielectric constant could be increased by 50%,
Moreover, no decrease in relative permittivity was observed at 1 GHz. Furthermore, when the addition ratio was changed to 20 parts by weight and 30 parts by weight, the relative permittivity could be increased by 80% as compared with the comparative example, and in this case as well, a sufficient relative permittivity could be obtained at 1 GHz. . However, in Example 26 in which 40 parts by weight was added, there was a short circuit, so 1 GHz
In order to form a capacitor layer 15 which has a sufficient dielectric constant and is unlikely to be short-circuited, it is understood that the addition ratio of rhenium oxide is preferably 1 to 30 parts by weight.

Although the capacitor of the above-mentioned embodiment is formed by the green sheet method, in another embodiment, the built-in capacitor may be formed by the printing method.

As is clear from these results, in the alumina ceramic laminate 11 according to the above-mentioned embodiment, the high dielectric constant layer 1 mainly composed of alumina and rhenium metal was used.
Since 3 is provided inside, it is possible to reduce the number of layers of the laminated body and to reduce the size, thus increasing the yield and reducing the cost. Further, since the capacitor layer 15 is built in, it is not necessary to connect a large capacitor to the outside, and the reactance of the package does not increase,
High reliability because there is no possibility of short-circuiting, and 1
Since it has excellent frequency characteristics that the relative permittivity does not decrease even at GHz, the alumina ceramics laminated body 1 that sufficiently corresponds to the increase in operating frequency accompanying the increase in speed of LSI.
1 can be provided.

[0022]

As described above in detail, the alumina ceramic laminate according to the present invention has a high dielectric constant layer mainly composed of alumina and metallic rhenium dispersed therein, and contains metallic rhenium. By dispersing, the relative permittivity can be increased, the number of laminated layers can be reduced, and the size can be reduced. In addition, the yield can be increased and the cost can be reduced. In addition, since there is no possibility of short-circuiting, the reliability is high and the frequency characteristics are excellent, so that it is possible to cope with the increase in operating frequency accompanying the increase in speed of LSI.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an alumina ceramics laminate according to the present invention.

[Explanation of symbols]

 11 Alumina ceramics laminated body 13 High dielectric constant layer

Claims (1)

[Claims] 1. An alumina ceramics laminated body having a high dielectric constant layer mainly containing alumina and metallic rhenium dispersed therein.