JPH0350709A - Capacitor - Google Patents

Abstract

PURPOSE:To make a capacitor compact, light and contrive a reduction in its manufacturing cost by using either or both of fluorinated or fluoroalkylation monomers out of two kinds of the monomers having benzene rings as skeletons and using a thin film which is formed with a vapor deposition polymerization process as a dielectric substance. CONSTITUTION:Internal electrode layers 2 consisting of aluminum alloy are formed on a cleaned alumina substrate 1 and dielectric layers 3 consisting of phloroalkylation aromatic polyurea are formed with a vapor deposition polymerization process by using 2,2-bis[4-(4- aminophenoxyphenyl)]hexaphloropropane and diphenylmethanediisocyanate as monomers. Then, after laminating alternately in the same way, a protecting film layer 4 consisting of silicon nitride is formed and further, an external electrode layer 5 consisting of nickel-boron alloy is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capacitor used in hybrid integrated circuits, electronic circuits such as electronic equipment, information equipment, and the like.

Due to the trend toward smaller and lighter weight conventional technological equipment, higher functionality and higher performance, higher density of electronic circuits due to the adoption of highly integrated circuits, and the spread of automatic insertion, electronic components are becoming smaller and higher performance. The demands are becoming stronger and stronger. Under these circumstances, various attempts are being made to develop capacitors to make them smaller and to improve their performance. The capacitance per unit volume of a capacitor is proportional to the permittivity of the dielectric and inversely proportional to the square of the thickness of the dielectric.

Therefore, in order to downsize conventional capacitors, it is necessary to increase the dielectric constant of the dielectric or reduce the thickness of the dielectric. In addition, since the electrical properties of a capacitor, such as the temperature dependence and frequency dependence of capacitance and dielectric loss, are mostly determined by the inherent characteristics of the material used as the dielectric, various materials have been studied. There is.

Here, many studies have already been conducted on multilayer thin film capacitors to significantly reduce the size of the capacitor by reducing the thickness of the dielectric, and the thin film lamination method and laminated structure of multilayer thin film capacitors are well known.

(For example, JP-A-55-91112, JP-A-56-
See No. 144523. ) That is, aluminum oxide formed by a physical vapor deposition method (PVD method) such as a vacuum evaporation method or a sputtering method,
After alternately laminating dielectric layers made of silicon oxide, titanium oxide, strontium titanate, etc. and internal electrode layers made of palladium, silver, nickel, etc., the external electrodes, which will become lead terminals from the internal electrode layers, are made with conductive paste. Multilayer thin film capacitors formed by baking are generally known.

On the other hand, high-performance capacitors using inorganic dielectrics have also been developed, but the permittivity of the high-performance dielectrics used in these capacitors decreases as performance improves. Capacitors were difficult to obtain.

Problems to be Solved by the Invention Conventionally, in multilayer thin film capacitors, it has been difficult to form extremely thin dielectric layers and internal electrode layers by using physical vapor deposition (PVD) methods such as vacuum evaporation and sputtering. This has led to the miniaturization of capacitors.

However, when forming a dielectric layer by sputtering an inorganic material such as aluminum oxide, silicon oxide, titanium oxide, or strontium titanate, it takes about 10,000 people to obtain the dielectric strength required for a capacitor. thickness is required, and in order to further reduce the size,
This had become an issue. Furthermore, when the above-mentioned inorganic dielectric materials are used to improve the performance of capacitors, the dielectric constant of the materials decreases significantly, which has been a major problem in miniaturization.

The present invention solves the above-mentioned problems, and by using a thin film formed by a vapor deposition polymerization method with good withstand voltage characteristics as a dielectric material, a capacitor can be significantly downsized, and a benzene ring is used as a skeleton. By using a thin film formed by vapor deposition polymerization using one or both of the two monomers that are fluorinated or fluoroalkylated as the dielectric material, the performance of the capacitor can be significantly improved. The aim is to

Means for Solving the Problems In order to solve the above problems, the present invention uses a monomer in which one or both of two types of monomers having a benzene ring as a skeleton are fluorinated or fluoroalkylated. It has a structure in which a thin film formed by vapor deposition polymerization is used as a dielectric, and the thin film dielectric and internal electrodes are alternately laminated.

Function In conventional multilayer thin film capacitors, dielectrics are formed by physical vapor deposition (PVD) methods such as vacuum evaporation and sputtering. For example, aluminum oxide, silicon oxide, titanium oxide, etc. When forming oxide dielectrics such as strontium titanate and strontium titanate, the respective compositions are not formed as they are, but are formed while containing oxygen defects. The withstand voltage of a dielectric material containing this oxygen defect is low, so in order to obtain the withstand voltage necessary for a capacitor, it is necessary to
The membrane thickness required is as thick as that of a deer.

On the other hand, the thin film dielectric formed by the vapor deposition polymerization method of the present invention is made of an organic compound such as aromatic polyurea, and contains oxygen defects in the oxide dielectric that reduce the withstand voltage as described above. An extremely uniform thin film with few defects is obtained. Therefore, it is possible to obtain sufficient withstand voltage necessary for a capacitor with a film thickness of about 1,500 people, and the dielectric material can be made thinner without reducing the withstand voltage.

Embodiments Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

Example 1 An internal electrode layer made of an aluminum alloy was formed on a previously cleaned alumina substrate, and then 2 was added as a monomer.
,2-bis[4-(4-aminophenoxyphenyl)]
A dielectric layer made of fluoroalkylated aromatic polyurea is formed by vapor deposition polymerization using hexafluoropropane and diphenylmethane diisocyanate. Thereafter, after alternately laminating layers in the same manner, a protective film layer made of silicon nitride is formed, and an external electrode layer made of a nickel-boron alloy is further formed by electroless plating.

Example 2 An internal electrode layer made of an aluminum alloy was formed on an alumina substrate that had been cleaned in advance, and then 2 was added as a monomer.
．． A dielectric layer made of fluoroalkylated aromatic polyamide is formed by vapor deposition polymerization using 2-bis(4-aminophenyl)hexafluoropropane and terephthalic acid chloride. Thereafter, after alternately laminating layers in the same manner, a protective film layer made of silicon nitride is formed, and an external electrode layer made of a nickel-boron alloy is further formed by electroless plating.

Example 3 An internal electrode layer made of an aluminum alloy was formed on an alumina substrate that had been cleaned in advance, and then 2 was added as a monomer.
．． A fluoroalkylated aromatic polyamic acid is formed by vapor deposition polymerization using 2-bis(4-aminophenyl)hexafluoropropane and pyromellitic dianhydride, and then heated and dehydrated to form a fluoroalkylated aromatic polyamic acid. A dielectric layer made of alkylated aromatic polyimide is obtained. After that, after laminating the layers alternately in the same way, a protective film layer made of silicon nitride is formed.
Furthermore, an external electrode layer made of a nickel-boron alloy is formed by electroless plating.

Comparative Example 1 An internal electrode layer made of an aluminum alloy was formed on a previously cleaned alumina substrate, and then a dielectric layer made of an aromatic polyurea was deposited using para-phenylene diamine and diphenylmethane diisocyanate as monomers. Formed legally. Thereafter, after laminating layers alternately in the same manner, a protective film layer made of silicon nitride is formed, and further,
An external electrode layer made of a nickel-boron alloy is formed by electroless plating.

Comparative Example 2 An internal electrode layer made of an aluminum alloy is formed on an alumina substrate that has been cleaned in advance, and then a dielectric layer made of strontium titanate is formed by a sputtering method. Thereafter, after alternately laminating layers in the same manner, a protective film layer made of silicon nitride is formed, and an external electrode layer made of a nickel-boron alloy is further formed by electroless plating.

FIG. 1 is an element cross-sectional view showing the structure of a capacitor in an embodiment of the present invention.

Internal electrode layers 2 and dielectric layers 3 are alternately laminated on an insulating substrate 1, and a protective film layer 4 is further applied thereon, excluding a portion near both ends of the non-opposed portions of the internal electrode layer 2. After forming the thin film layer 5 so as to cover the insulating substrate 1 in the vicinity thereof, the external electrode layer 5 is formed on both ends of the insulating substrate 1 including the portions of the internal electrode layer 2 that are not covered by the protective film layer 4. There is.

FIG. 2 shows the relationship between the dielectric film thickness and withstand voltage in a capacitor having the same configuration as FIG. 1. (The area of the opposing parts of the internal electrodes is constant at 15 mm2) In Fig. 2, straight line A is of Example 1, straight line B is of Example 2, straight line C is of Example 3, and straight line is of Comparative Example 1, straight line E. shows the relationship between the dielectric film thickness and withstand voltage in the capacitor of Comparative Example 2.

As is clear from the results shown in Figure 2, strontium titanate thin films, which are inorganic oxide dielectrics that have been extensively studied, and organic dielectric thin films formed by vapor deposition polymerization. The difference in withstand voltage is obvious. In other words, in order to obtain the withstand voltage necessary for a capacitor, the capacitor of Comparative Example 2 requires a dielectric film thickness of about s, ooo people, whereas the capacitor of Example 1 and Example In the capacitors of Example 2 and Example 3, the same level of withstand voltage can be obtained if the dielectric film thickness is approximately 1.500.

FIG. 3 shows the temperature dependence of the dielectric constant and dielectric loss of a capacitor having the same configuration as FIG. 1.

In FIG. 3, curve A shows the temperature dependence of the dielectric constant and dielectric loss of the capacitor of Example 1, curve B of Example 2, curve C of Example 3, and curved line of Comparative Example 1. It is something.

As is clear from the results shown in FIG. 3, the capacitor of the example of the present invention exhibits extremely good characteristics in terms of temperature dependence of dielectric constant and dielectric loss.

Note that materials that can be formed by vapor deposition polymerization include polyimide, polyamide, polyurea, etc.
Since it is an addition polymerization, an aromatic polyurea is most preferable because it does not produce polymerization by-products, does not require post-treatment, and has excellent heat resistance.

Effects of the Invention As described above, according to the present invention, it is possible to significantly reduce the thickness of the dielectric film, thereby making it possible to reduce the size, weight, and cost of the capacitor. It has become possible to realize this, and its industrial potential is extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a capacitor according to an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the relationship between dielectric film thickness and withstand voltage in the capacitor of the same embodiment, and FIG.
Figures (a) and (b) are characteristic diagrams showing the temperature dependence of the dielectric constant and dielectric loss of the capacitor of the same example. 1... Insulating substrate, 2... Internal electrode layer, 3... Dielectric layer, 4... Protective film layer,
5...External electrode layer.

Claims (7)

[Claims] (1) Among the two types of monomers with a benzene ring as the skeleton,
The dielectric is a thin film formed by vapor deposition polymerization using a fluorinated or fluoroalkylated monomer, and the thin film dielectric and internal electrodes are alternately laminated. capacitor. (2) The capacitor according to claim 1, wherein the thin film formed by vapor deposition polymerization is a fluorinated or fluoroalkylated aromatic polyurea. (3) The capacitor according to claim 1, wherein the thin film formed by vapor deposition polymerization is a fluorinated or fluoroalkylated aromatic polyamide. (4) The capacitor according to claim 1, wherein the thin film formed by vapor deposition polymerization is a fluorinated or fluoroalkylated aromatic polyimide. (5) Claim 1 in which one of the two monomers having a benzene ring skeleton is an aromatic diamine and the other monomer is an aromatic diisocyanate.
Capacitors listed in section. (6) The capacitor according to claim 1, wherein one of the two monomers having a benzene ring as a skeleton is an aromatic diamine, and the other monomer is an aromatic dicarboxylic acid chloride. (7) Claim 1 in which one of the two monomers having a benzene ring skeleton is an aromatic diamine and the other monomer is an aromatic tetracarboxylic acid.
Capacitors listed in section.