JPS61251110A - Ceramic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) A method of forming a thin film dielectric ceramic layer.

(2) A method of making the thickness of the 'C# electric ceramic layer as thin as possible, which aims to microcrystallize the dielectric ceramic material.

■A method of forming an insulating layer at the grain boundaries of a thin film semiconductor ceramic layer to obtain a "C grain boundary insulation type dielectric ceramic layer."

(2) Among the methods (2) to (2) above, there is a method in which internal electrodes are formed between a plurality of dielectric ceramic layers to form a laminated ceramic capacitor to further increase the capacitance of C1.

(The point at which the invention is determined) However, after thinning the dielectric ceramic layer by the above method, the electric charge for extracting the capacitance can be reduced by sputtering, vacuum evaporation, or ion grating. When a °C ceramic capacitor is formed using a vapor phase deposition method or a method without any consideration, various troubles occur. What is particularly noticeable is the deterioration of the breakdown resistance when used at high temperatures.

The biggest cause of this trouble is that the dielectric ceramic is made of metal oxide, and the electrodes are made of metal.

That is, according to such a combination, it is thought that the exchange of C1 oxygen occurs as an inevitable phenomenon at the interface where the metal fluoride constituting the dielectric ceramic and the metal constituting the electrode come into contact.

In this exchange of oxygen, C is hardly recognized at room temperature, but as the temperature rises, the exchange of oxygen becomes more K.

For example, what about dielectric ceramics? 0.0. % electrode is C
To explain this using an example of a ceramic capacitor made of 150C, the capacitance at a high temperature, for example, 150C.

Tie and Cu change as follows.

Oxidation (O < (R) changes significantly, and its value generally decreases by more than two orders of magnitude.

Such a decrease is particularly noticeable when the dielectric ceramic layer is made thinner, and the ceramic capacitors obtained by the above-mentioned improved means for making the ceramic capacitor thinner have the same -Cvl. This is a matter of concern.

(Purpose of the Invention) This invention has a structure in which the electric cell is not completely damaged when used at high temperatures, so that changes in dielectric constant and deterioration in insulation resistance do not occur. The purpose is to provide highly reliable ceramic capacitors.

(Structure of the Invention) In other words, in the invention, iron oxide, zirconium oxide, indium oxide, tin oxide, or lead oxide is used between a dielectric ceramic and an external connection electrode formed on the surface of the dielectric ceramic. A ceramic capacitor characterized by interposing a zinc oxide layer containing 5 to 999 mol of at least one kind.

Here, dielectric ceramics [are those with high dielectric constants such as barium titanate-based and strontium titanate-based, and also those with high permittivity such as titanium oxide-based, magnesium titanate-based, magnesium oxide-titanium oxide-based, and silicon oxide-based. , etc., and grain boundary insulated dielectric ceramics in which the crystal grain boundaries of semiconductor ceramics are made into insulators.

In addition, for dielectric ceramics with a thickness of 50 μm or less, a zinc oxide layer (hereinafter referred to as a zinc oxide layer) containing each of the metal oxides listed above (excluding cases where # requires an explanation) is used as a dielectric ceramic. The effect is most pronounced when it is interposed between the ceramic and the external connection electric sign. If the thickness of the dielectric ceramic exceeds 50 μm, reduction of the dielectric ceramic by the Ct electrode occurs during high-temperature use.
Since the dielectric ceramic has a sufficient thickness in case C, changes in dielectric constant and deterioration in insulation resistance do not occur noticeably. Therefore, the dielectric ceramic according to the invention is particularly effective for those having a thickness of 50 μm or less. However, there is no problem in applying the invention of C to a dielectric ceramic having a thickness exceeding 50 μm, and interposing the zinc oxide layer between the dielectric ceramic and the external connection electrode is optional. be.

As described above, the zinc oxide layer contains at least one of iron oxide, zirconium oxide, indium oxide, tin oxide, and lead oxide, but these metal oxides can be in various oxide states. There are also Fe,
O,'rn, o, , SnO,.

PI) Converted to O, 1111 of C9,5-999 molt.
contained within. The reason why the metal oxide content is limited to the above range is that if it is less than α5 molt, 50 Mn
Constructing an insulating layer of zinc oxide having a resistance value of more than /
When it exceeds 0.5 molti, the conductive film becomes less than 50n/port. On the other hand, the 999 molti type, the toothpick, and the type in which all of the zinc oxides are replaced with the above-mentioned metal oxides have already been filed and have been excluded from this invention to avoid duplication.

As a method for forming the zinc oxide layer, a thin film forming method such as f-sputtering method, ion grating method, vacuum evaporation method, etc. is used. When forming a zinc oxide layer by sputtering, for example, it can be carried out by using metallic zinc containing the various metals mentioned above as a target and by setting the atmosphere during sputtering to a mixed gas of argon and oxygen. . In addition, when forming a zinc oxide layer containing each of the above metal oxides by vacuum evaporation,
For example metal zinc or gold! It can be obtained by heating a mixture of zinc powder and each of the above metals or metal powders. Furthermore, after forming a zinc layer containing each of the above metals by a sputtering method, a vacuum evaporation method, or an ion blating method, the zinc oxide layer can be formed by thermal oxidation.

This zinc oxide layer is preferably formed to have a thickness of 2 μm or less. This is I! when it exceeds 2 μm! i
, B, and R become high.

The type of metal used for the external connection pot C is not particularly limited, and may be made of commonly used metals, such as A9.
ALL, Cr, Zr, V, Ni, Zn,
Cu, Sn.

Pb-Ejn, Mn, go, W, 'I'i,
One type or a combination of two or more of Pi, AIF, etc. may be used, and this yHL container for external connection may have a multilayer structure.
There are l-A9, etc.

Examples of the structure of the ceramic capacitor according to the present invention include a ceramic capacitor made of single-layer #1 ceramic, a multilayer ceramic capacitor, etc. Also, the various ceramic capacitors described above are of the grain boundary insulated type. The present invention is also applicable to these cases.

(Example) Hereinafter, this invention will be described in detail in accordance with an example.

Example t Ceramic dielectric raw material powder having the following composition was prepared.

Nt), Ti, O,: 63 mol%, 31110m: 14
Mol%, Tie,: 23 mole This raw material powder is mixed with polyvinyl alcohol as a binder,
A 'C slurry was prepared by mixing with a surfactant, a dispersant, and water. Next, using this slurry, a ceramic green sheet with a thickness of 35 μm was prepared by the C doctor blade method.

This ceramic green sheet is 7.0M long.

The sheet was cut to a size of 5.0 fl in width, and Muku-Pa paste of 7Qwt and P13Qwt was printed on this sheet. Eleven ceramic green sheets with internal electrodes formed in this manner were stacked so that the internal electrodes were exposed at the end faces of the laminate. This laminate was placed in the air for 125 minutes.
A C sintered unit was obtained by firing at 0 t'. The thickness of each dielectric layer of the obtained laminate was 20 μm.

Next, the internal electrodes of this laminated sintered unit were exposed and a zinc oxide layer was formed under the following conditions in a sputtering atmosphere:
Argon pressure containing 50% oxygen =
5Xll”-”TOrr target: 5 inch diameter, 51 g thick zinc plate voltage, t2KV D, C as shown in Table 1.

Current: 120 m sputtering time: continued for 45 minutes On top of the °C1 zinc oxide layer, a first layer of external connection electrode C1 was first formed as a solder heat-resistant layer and a °C N1 layer was formed by sputtering.

This Ni layer was formed under the following conditions.

Sputtering atmosphere: Argon pressure Crab 2X10 Torr target: 5 inch diameter, 24 inch thick nickel plate Voltage: 49QV D,C.

Current = 2.0 μm Time = 15 minutes Film thickness! Furthermore, a second layer of external connection electrode is placed on top of the N1 layer.
An Af layer was formed by sputtering.

This Ap layer is a layer that can be soldered and plays the role of C.

The formation of 19 layers was carried out under the following conditions.

Sputtering atmosphere: Argon pressure Crab 2X10 Torr target: 5 inch diameter, 511s thick mu9 plate voltage, 54QVD, C.

Electric 15! : 2.0 μm Time = 6 minutes Film thickness: 1 μm For the multilayer capacitor obtained through the above steps,
A high-temperature accelerated load life test was conducted under the following conditions.
Insulation resistance (R) after 0 hours was measured. By the way, the initial value of the insulation resistance (R) of this multilayer capacitor is io
It was Q. In addition, it was installed in an atmosphere with a temperature of 45 r and a relative humidity of 95 h, applied a rated voltage SOV, and measured the insulation resistance (R) after 500 hours (high temperature accelerated load life test).

The measurement results are shown in Table 1.

In Table 1, items with a cross mark are outside the scope of the invention, and all others are within the scope of the invention.

Sample numbers 1-9 to 1-11 in Table 1 showed severe deterioration in insulation resistance.
Measurement was not possible 0 Comparative example was performed under the same conditions as Example 1 without forming a zinc oxide layer on the laminated sintered unit obtained in Example 1, but with a Ni layer as the first layer external connection electrode. and A, which is the second layer external connection electrode.
A Q layer was formed to create a multilayer capacitor.

When this multilayer capacitor was tested in the same manner as in Example 1, the insulation resistance (R) was 100% after 10 hours.
The volume decreased to 10 fl after 25 hours.

Example 2 ElrTiO: 99.3 molti, "1 type Os:
0.3 morchi, 810 mushrooms:! 12 morchi, ml mushroom Om:
Each component was weighed so as to have a composition of more than 0.2 mol, and 10% by weight of an organic binder was added to the weighed raw materials, and the mixture was rotated in a ball mill for 16 hours to thoroughly mix and pulverize.

After granulating this, 1000Ki! Molded at a pressure of /d・C
A disc-shaped molded body was obtained. This molded body was 1350t', 2
Fired under certain conditions. Pb on the surface of the obtained porcelain.

Apply a metal oxide such as B1 and apply 1000 to 1200 tons
The grain boundaries of the porcelain were heat-treated at a temperature of 100 mL to convert them into insulators, creating a grain-boundary insulated semiconductor porcelain body.

Using this semiconductor ceramic body, a zinc oxide layer, a first layer of external connection electrodes, and a second layer of external connection electrodes shown in Table 2 were formed on the surface of the semiconductor ceramic body in the same manner as in Example 1. , created a grain-boundary, low-density type semiconductor porcelain capacitor.

This capacitor was subjected to the high temperature accelerated load life test described in Example IK of RiiC1. The results are shown in Table 2. The initial value of insulation resistance (R) was 5×1°010n or more.

Sample numbers 2-9 to 2-11 had poor insulation resistance deterioration.
I was deaf because I couldn't measure it.

Comparative Example 2 Using the grain boundary insulated semiconductor porcelain body obtained in Example 2,
Without forming a zinc oxide layer on the surface of this ceramic body, under the same conditions as in Example 1, a Ni layer, which is the first layer of external connection electrode, and a burr layer, which is the second layer of external connection electrode, are formed. Then, a grain boundary insulated semiconductor ceramic capacitor was created.

When this capacitor was tested in the same manner as in Example 1, the insulation resistance (IR) decreased to 10Ω after 10 hours, and deteriorated to 10Q after 25 hours.

Example & On an alumina substrate, an rAf layer and a Ni layer were formed as a lower electrode in the same manner as in Example 1, and a zinc oxide layer was also formed as shown in Table 1 of Actual Column 1. Sample number 1-1
A multilayer film was formed in the same manner as in Example 1 using the following target.

Next, Ei, which is a dielectric ceramic, is deposited on the zinc oxide layer.
iO, film by high frequency sputtering method! It was formed to a thickness of 75,000 mm.

The conditions for forming the S10 layer by high frequency sputtering are as follows.

Sputtering atmosphere: A quartz plate containing 50% oxygen Input power = soow Time = 100 minutes 810 times film thickness! After that, a zinc oxide layer was formed on the S'Ovm in the same manner as in Example 1 using the target of sample number 1-5 shown in Table 1 of Example 1, and further coated with K. On top of that, an N1 layer and a bulk layer were sequentially formed in the same manner as in Example 1.
10. A thin film capacitor consisting of

This capacitor was subjected to the high temperature accelerated load life test described in Example 1. As a result, while the initial insulation resistance (R) was 10 Ω, it was 10 Q after 100 hours.

Comparative Example 5 When creating a thin film capacitor according to Example 6,
A thin film capacitor was fabricated by carrying out the method described in Example 5 without forming a zinc oxide layer.

When this capacitor was tested in the same manner as in Example 1, the insulation resistance was reduced to 10f1 (Effect) As described above, according to the present invention, the dielectric ceramic and the external connection By interposing a zinc oxide layer between the dielectric ceramic and the electrode, it is possible to prevent the reduction of the dielectric ceramic caused by the electrode during high-temperature use, thereby reducing the deterioration of its waxy properties, especially the insulation resistance. This has the effect of preventing deterioration.

Claims (6)

[Claims] (1) In a ceramic capacitor including a dielectric ceramic and an external connection electrode formed on the surface of the dielectric ceramic, iron oxide, zirconium oxide, At least one of indium, tin oxide, and lead oxide from 0.5 to 9
A ceramic capacitor characterized in that a zinc oxide layer containing 9.9 mol% is formed. (2) A first external connection electrode is formed on the substrate, a dielectric ceramic is formed on the first external connection electrode, and a second external connection electrode is formed on the dielectric ceramic. In the ceramic capacitor formed, at least one of iron oxide, zirconium oxide, indium oxide, tin oxide, and lead oxide is present between the dielectric ceramic and the first external connection electrode and the second external connection electrode. Seeds 0.
The ceramic capacitor according to claim 1, wherein a zinc oxide layer containing 5 to 99.9 mol% of zinc oxide is formed. (3) A laminated dielectric ceramic element body consisting of multiple layers of dielectric ceramic and multiple layers of internal electrodes that are stacked on top of each other via the dielectric ceramic to form capacitance. In the laminated ceramic capacitor in which a pair of external connection electrodes for taking out capacitance are connected to predetermined ones of the internal electrodes, the dielectric ceramic body and the external connection electrodes are formed. Between iron oxide, zirconium oxide, indium oxide, tin oxide,
0.5 to 99.9 mol% of at least one type of lead oxide
The ceramic capacitor according to claim 1, wherein a zinc oxide layer containing zinc oxide is formed. (4) The ceramic capacitor according to claims (1) to (3), wherein the dielectric ceramic has a thickness of 50 μm or less. (5) At least one of the above iron oxide, zirconium oxide, indium oxide, tin oxide, and lead oxide with a concentration of 0.5 to 99%
．． The ceramic capacitor according to claims (1) to (3), wherein the thickness of the zinc oxide layer containing 9 mol% is 2 μm or less. (6) At least one of the above iron oxide, zirconium oxide, indium oxide, tin oxide, and lead oxide with a concentration of 0.5 to 99%
．． The ceramic capacitor according to claims (1) to (3), wherein the zinc oxide layer containing 9% is formed by any one of a sputtering method, a vacuum evaporation method, and an ion plating method.