JP6915281B2 - Dielectric composition and electronic components - Google Patents

Description

The present invention relates to a dielectric composition and an electronic component comprising a dielectric layer composed of the dielectric composition. In particular, the present invention relates to a dielectric composition suitable for a dielectric layer of electronic components such as multilayer ceramic capacitors and thin film capacitors.

As electronic components such as multilayer ceramic capacitors and thin film capacitors have become smaller and more sophisticated, the dielectric materials used for these dielectric layers include materials that exhibit a high relative permittivity and a low dielectric loss. Desired. Further, since a DC voltage is applied to the electronic components when the electronic device on which these electronic components are mounted is operated, the insulating property of the dielectric layer is maintained even under a high electric field strength due to the DC voltage. There is a need.

Currently, the relative dielectric constant of BaTiO ₃ based dielectric compositions are widely used as the dielectric material is about 500 to 6,000, the dielectric constant is seldom exceed 10000.

Various dielectric materials that are different from the BaTiO ₃ type dielectric material and exhibit a high relative permittivity have also been studied. For example, in Patent Document 1, TiO ₂ having a rutile-type crystal structure is co-substituted with a + trivalent element A such as In and Ga and a + pentavalent element B such as Nb and Ta (A ³⁺ , B ^5+). ) TiO _2- based dielectric materials are disclosed. According to Patent Document 1, this dielectric material has a high relative permittivity of over 10,000 and a low relative permittivity of over 10,000 by utilizing an electron pinning defect dipole mechanism obtained by co-substituting a +3 valent element and a +5 valent element. It is compatible with dielectric loss.

Further, in Patent Document 2, a dielectric material which is made into a semiconductor by containing Nb ₂ O _{5 in the main component TiO 2 and further contains Bi 2} O ₃ , CeO ₂ , and La ₂ Ti ₂ O _{7 is described.} It is disclosed that this dielectric material also has both a huge relative permittivity exceeding 10,000 and a low dielectric loss.

Special Table 2014-53138 Japanese Unexamined Patent Publication No. 55-9204

However, in the dielectric material described in Patent Document 1, since electrons are localized (pinned) by utilizing oxygen defects, a high DC voltage is applied to an electronic component provided with a dielectric layer using the dielectric material. When is applied, there is a problem that oxygen defects are easily moved, localized electrons are easily hopping and conducted, and the specific resistance is sharply lowered.

Further, in the dielectric material described in Patent Document 2, the contained Bi ₂ O ₃ , CeO ₂ , and La ₂ Ti ₂ O ₇ form a grain boundary having a high specific resistance, but the grain boundary itself. Is extremely thin (for example, 10 nm or less), so that when a high DC voltage is applied, dielectric breakdown occurs and the specific resistance sharply decreases, which is the same problem as in Patent Document 1.

The present invention has been made in view of such an actual situation, and an object of the present invention is to exhibit a high relative permittivity (for example, 10,000 or more) and a high specific resistance (for example, 5 V /) even under a high electric field strength when a DC voltage is applied. in [mu] m, and an object thereof is to provide a dielectric composition having 1.00 × 10 ⁸ Ωcm or higher), the electronic component comprising a formed dielectric layer from the dielectric composition.

In order to achieve the above object, the dielectric composition of the present invention is used.
[1] represented by the formula _{Ti 1.0000-x-y-z} A x B y C z O 2 + δ, comprise a composite oxide having a rutile-type crystal structure as a main component,
One or more elements in which A is selected from the group consisting of Al, Ga, In and rare earth elements,
One or more elements in which B is selected from the group consisting of Si, Zr and Hf,
C is one or more elements selected from the group consisting of V, Nb, Sb and Ta.
x, y, and z are
x> 0, y> 0, z> 0,
0.0050 ≦ x + y + z ≦ 0.3000,
2.0000 ≦ (x + z) / y ≦ 20.0000,
0.8000 ≤ x / z ≤ 1.2000
It is a dielectric composition characterized by satisfying the relationship of.

[2] The dielectric composition according to [1], wherein x and z satisfy a relationship of 1.0200 <x / z ≦ 1.2000.

[3] x, y, and z are
0.8000 ≤ x / z <0.9800,
2.0000 ≦ (x + z) / y ≦ 9.0000
The dielectric composition according to [1], which is characterized by satisfying the relationship of.

[4] x, y, and z are
0.9800 ≤ x / z ≤ 1.0200,
7.0000 <(x + z) / y <17.0000
The dielectric composition according to [1], which is characterized by satisfying the relationship of.

[5] An electronic component comprising a dielectric layer containing the dielectric composition according to any one of [1] to [4].

Due to the above-mentioned characteristics, the dielectric composition of the present invention exhibits a high relative permittivity (for example, 10,000 or more) and a high specific resistance (for example, 5 V / μm) even under a high electric field strength when a DC voltage is applied. in, it is possible to provide a dielectric composition, an electronic component comprising a formed dielectric layer from the dielectric composition having 1.00 × 10 ⁸ Ωcm or higher).

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail in the following order based on specific embodiments.
1. 1. Multilayer Ceramic Capacitor 1.1 Overall Composition of Multilayer Ceramic Capacitor 1.2 Dielectric Layer 1.2.1 Dielectric Composition 1.3 Internal Electrode Layer 1.4 Terminal Electrode 2. Manufacturing method of multilayer ceramic capacitors 3. Effect in this embodiment 4. Modification example

(1. Multilayer ceramic capacitor)
(1.1 Overall configuration of multilayer ceramic capacitor)
As shown in FIG. 1, the multilayer ceramic capacitor 1 as an example of the electronic component according to the present embodiment has an element main body 10 having a structure in which a dielectric layer 2 and an internal electrode layer 3 are alternately laminated. A pair of external electrodes 4 that conduct with the internal electrode layers 3 alternately arranged inside the element body 10 are formed at both ends of the element body 10. The shape of the element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Further, the dimensions are not particularly limited, and the dimensions may be appropriate according to the intended use.

(1.2 Dielectric layer)
The dielectric layer 2 is composed of the dielectric composition according to the present embodiment, which will be described later. As a result, the multilayer ceramic capacitor having the dielectric layer 2 exhibits a high relative permittivity (for example, 10,000 or more) and has a high specific resistance (for example, 5 V / μm) even under a high electric field strength when a DC voltage is applied. in may indicate 1.00 × 10 ⁸ Ωcm or higher).

The thickness of the dielectric layer 2 per layer (interlayer thickness) is not particularly limited, and can be arbitrarily set according to desired characteristics, applications, and the like. Usually, the interlayer thickness is preferably 100 μm or less, more preferably 30 μm or less. In the present embodiment, the lower limit of the interlayer thickness can be set to, for example, about 3.0 μm, but the thickness may be thinner than this. According to the dielectric composition according to the present embodiment, even when the interlayer thickness is in the above range, the above-mentioned effect can be sufficiently obtained.

The number of laminated dielectric layers 2 is not particularly limited, but in the present embodiment, it is preferably 20 or more, and more preferably 50 or more.

(1.2.1 Dielectric Composition)
The dielectric composition according to the present embodiment contains a composite oxide having a rutile-type crystal structure as a main component. The composite oxide expressed by the formula _{Ti 1.0000-x-y-z} A x B y C z O 2 + δ, in titanium dioxide (TiO _2), a part of the titanium element (Ti), predetermined It has a composition replaced by an element. Further, in the composite oxide, the amount of oxygen (O) may be a stoichiometric ratio, or may be slightly deviated from the stoichiometric ratio due to oxygen defects or the like. The amount of deviation from the stoichiometric ratio varies depending on the type of element to be substituted and the amount of substitution thereof, and is represented by "δ" in the above composition formula.

In the present embodiment, the elements substituting Ti are divided into three element groups (“A”, “B” and “C”) based on the valence (+4 valence) of Ti _{in TiO 2.} ..

"A" in the above composition formula is composed of an element having a valence of +3 valence, which is one less than the valence of Ti (+4 valence). That is, the element belonging to "A" is an acceptor. Specifically, "A" is one or more selected from the group consisting of Al, Ga, In and rare earth elements. The rare earth element is one or more selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. .. Therefore, "A" is from the group consisting of Al, Ga, In, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. One or more to be chosen.

The "x" in the above composition formula indicates the ratio (acceptor amount) in which "A" replaces Ti in the composite oxide. In this embodiment, x> 0, preferably 0.0010 or more. The upper limit of "x" is determined by the relationship with "y" and "z" described later.

"B" in the above composition formula is composed of an element having the same valence as the valence of Ti (+4 valence). Specifically, "B" is one or more selected from the group consisting of Si, Zr, and Hf, and preferably contains at least Zr.

“Y” in the above composition formula indicates the ratio of “B” substituting Ti (substitution amount of B) in the composite oxide. In this embodiment, y> 0, preferably 0.0010 or more. The upper limit of "y" is determined by the relationship between "x" described above and "z" described later.

"C" in the above composition formula is composed of an element having a valence of +5 valence, which is one higher in valence than the valence of Ti (+4 valence). That is, the element belonging to "C" is a donor. Specifically, "C" is one or more selected from the group consisting of V, Nb, Sb and Ta, and preferably contains at least Nb.

“Z” in the above composition formula indicates the ratio (donor amount) of “C” substituting Ti in the composite oxide. In this embodiment, z> 0, preferably 0.0010 or more. The upper limit of "z" is determined by the relationship with "x" and "y" described above.

In the present embodiment, the composite oxide contains "A" that acts as an acceptor and "C" that acts as a donor (replaces Ti), and further contains "B" having the same valence as Ti. (Replaces Ti). Then, "x", "y" and "z", that is, the substitution amount of "A" with respect to Ti (acceptor amount), the substitution amount of "B" and the substitution amount of "C" (donor amount) have a predetermined relationship. By controlling so as to satisfy, while exhibiting a very high dielectric constant (for example, 10,000 or more), a high specific resistance (for example, 1.0 × 10 at 5 V / μm) even under a high electric field strength when a DC voltage is applied. ⁸ Ωcm or more) can be obtained.

Specifically, the total substitution amount of the elements that replace Ti ("A", "B", and "C"), the ratio of the substitution amount of "B" to the total of the acceptor amount and the donor amount, the acceptor amount and the donor. It controls the ratio with the amount. In the present embodiment, the relationship that the total substitution amount is 0.0050 ≦ x + y + z ≦ 0.3000 is satisfied, and the ratio of the replacement amount of “B” to the total of the acceptor amount and the donor amount is 2.000 ≦ ( The relationship of x + z) / y ≦ 20.000 is satisfied, and the relationship of the ratio of the acceptor amount to the donor amount is 0.8000 ≦ x / z ≦ 1.2000.

In the present embodiment, the total replacement amount and the ratio of the replacement amount of "B" to the total of the acceptor amount and the donor amount are within the above ranges, so that the total replacement amount is high even under a high electric field strength when a DC voltage is applied. Specific resistance can be obtained. On the other hand, if the ratio of the total substitution amount and the substitution amount of "B" to the sum of the acceptor amount and the donor amount does not satisfy the above relationship, the specific resistance sharply decreases when a high DC voltage is applied. There is a tendency.

Further, by setting the total substitution amount and the ratio of the acceptor amount and the donor amount within the above ranges, a very high relative permittivity can be obtained. On the other hand, if the ratio of the acceptor amount to the donor amount is too small, a high relative permittivity can be obtained, but the dielectric loss tends to be large. Further, if the ratio between the acceptor amount and the donor amount is too large, a high relative permittivity tends not to be obtained.

Therefore, in order to achieve both a very high dielectric constant and a high resistivity under a high electric field strength when a DC voltage is applied, the total substitution amount of the element that replaces Ti, the substitution amount of "B", the acceptor amount, and the donor amount All of the ratio to the total and the ratio of the acceptor amount to the donor amount need to satisfy the above relationship.

For example, the following can be explained as a factor for obtaining a very high dielectric constant. _{That is, it is negatively charged by substituting a part of Ti of TiO 2} having a rutile crystal structure with a donor + pentavalent element "C" (at least one selected from V, Nb, Sb, and Ta). The generated electrons are generated. However, if only the donor is introduced, the hopping conduction of electrons is usually promoted, so that the resistivity is lowered.

Therefore, by further _{substituting a part of Ti of TiO 2} with the + trivalent element "A" (at least one selected from Al, Ga, In and rare earth elements) which is an acceptor, a positively charged oxygen defect Is generated, and the electrons generated by this generated oxygen defect are pinned. As a result, the movement of electrons is suppressed, so that the decrease in resistivity can be suppressed. At this time, the generated electrons move between the Ti-Ti lattices within the range of the pinning effect due to the oxygen defect, so that a defective dipole using the oxygen defect is formed, which is huge due to the existence of the defective dipole. It is possible to obtain the relative permittivity.

Further, as a factor for obtaining a high resistivity under a high electric field strength when a DC voltage is applied, it can be estimated as follows, for example. Oxygen defects generated by the introduction of the acceptor are easily moved when a high DC voltage is applied, and the influence of the pinning effect on the pinned electrons is reduced, so that hopping conduction of electrons is likely to occur. Therefore, under a high DC voltage, the specific resistance drops sharply.

In the present embodiment, in order to suppress this sudden decrease in resistivity, the + tetravalent element "B" (at least one selected from Si, Zr, and Hf) having the same valence as Ti is used as the Ti of _{TiO 2.} Partially substituted to control the substitution amount (acceptor amount) of the +3 valent element "A", the substitution amount (donor amount) of the +5 valent element "C", and the substitution amount of the +4 valent element "B". As a result, the interaction between these elements can suppress the movement of oxygen defects and enhance the effect of pinning electrons, and the decrease in resistivity can be suppressed even under high electric field strength when a DC voltage is applied. thinking.

Therefore, _{not only by introducing an acceptor and a donor to TiO 2} , but also by introducing an element having the same valence as Ti, unlike Ti, an interaction that cannot be obtained only by introducing an acceptor and a donor can be obtained. Can be caused. As a result, by setting the ratio of the substitution amount of "B" to the total of the acceptor amount and the donor amount within the above-mentioned range, a high relative permittivity and a high specific resistance under a high electric field strength when a DC voltage is applied can be obtained. It can be compatible.

In this embodiment, it is preferable that x and z satisfy the relationship of 1.0200 <x / z ≦ 1.2000. That is, by setting the substitution amount (acceptor amount) of "A" to be larger than the substitution amount (donor amount) of "C" in the above range ("A" rich range), the movement of oxygen defects can be suppressed and electrons can be suppressed. It is possible to further strengthen the pinning effect. As a result, a higher specific resistance tends to be easily obtained under a high electric field strength when a DC voltage is applied.

Further, when x and z satisfy the relationship of 0.8000 ≦ x / z <0.9800, the relationship of x, y and z is 2.0000 ≦ (x + z) / y ≦ 9.0000. It is preferable to be satisfied. That is, when the substitution amount (acceptor amount) of "A" is smaller than the substitution amount (donor amount) of "C" in the above range ("C" rich range), the substitution amount (acceptor amount) of "A" ) And the total amount of the substitution amount (donor amount) of "C" and the substitution amount of "B" (+ tetravalent element amount) within the above range, the movement of oxygen defects can be suppressed and electrons can be suppressed. It is possible to further strengthen the pinning effect. As a result, a higher specific resistance tends to be easily obtained under a high electric field strength when a DC voltage is applied.

Further, when x and z satisfy the relationship of 0.9800 ≦ x / z ≦ 1.0200, the relationship between x, y and z is 7.00000 <(x + z) / y <17.0000. It is preferable to be satisfied. That is, when the substitution amount (acceptor amount) of "A" and the substitution amount (donor amount) of "C" are within a range close to the equal amount, the substitution amount (acceptor amount) of "A" and "C" By setting the ratio of the total amount of the substitution amount (donor amount) of "B" to the substitution amount of "B" (+ tetravalent element amount) in the above range, the effect of suppressing the movement of oxygen defects and pinning electrons can be obtained. Can be further strengthened. As a result, a higher specific resistance tends to be easily obtained under a high electric field strength when a DC voltage is applied.

As described above, the dielectric composition according to the present embodiment can achieve both a high relative permittivity and a high specific resistance under a high electric field strength when a DC voltage is applied. It can be suitably used as a dielectric layer of an electronic component such as a thin film capacitor having a large back and a large capacity.

In addition, the dielectric composition according to the present embodiment may contain trace amounts of impurities, subcomponents, etc. within the range in which the effects of the present invention are exhibited. Examples of such a component include Mn, Ca, Ba, Zn and the like. Therefore, the content of the main component is not particularly limited, but is, for example, 70 mol% or more and 100 mol% or less with respect to the entire dielectric composition containing the main component.

(1.3 Internal electrode layer)
In the present embodiment, the internal electrode layers 3 are laminated so that their end faces are alternately exposed on the surfaces of the two opposing ends of the element body 10.

The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni, Ni-based alloys, Cu or Cu-based alloys are preferable. The Ni, Ni-based alloy, Cu, or Cu-based alloy may contain various trace components such as P in an amount of about 0.1% by mass or less. Further, the internal electrode layer 3 may be formed by using a commercially available electrode paste. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like.

(1.4 External electrode)
In the present embodiment, the pair of external electrodes 4 are formed at both ends of the element body 10 and are connected to the exposed end faces of the alternately arranged internal electrode layers 3 to form a capacitor circuit. The conductive material contained in the external electrode 4 is not particularly limited. In this embodiment, various conductive materials such as inexpensive Ni, Cu, highly heat-resistant Au, Ag, Pd, and alloys thereof can be used. The thickness of the external electrode 4 may be appropriately determined depending on the application and the like, but is usually preferably about 10 to 50 μm.

(2. Manufacturing method of multilayer ceramic capacitor)
Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 shown in FIG. 1 will be described below.

As for the multilayer ceramic capacitor 1 according to the present embodiment, as in the case of the conventional multilayer ceramic capacitor, a green chip is produced by a normal printing method or a sheet method using a paste, and the green chip is fired to obtain an element main body. It is manufactured by printing or transferring an external electrode on the element body and firing it. Hereinafter, the manufacturing method will be specifically described.

First, a starting material for the dielectric composition is prepared. As a starting material, a metal oxide contained in the composite oxide constituting the above-mentioned dielectric composition, a mixture thereof, or a composite oxide can be used. In addition, various compounds that become oxides and composite oxides by firing, such as carbonates, oxalates, nitrates, hydroxides, and organic metal compounds, can be appropriately selected and mixed for use. For example, when the above "A" is Ga, "B" is Zr, and "C" is Nb, TiO ₂ powder, Ga ₂ O ₃ powder, ZrO ₂ powder, and Nb ₂ O ₅ powder may be prepared. good. The average particle size of each powder is preferably 1.0 μm or less.

The prepared starting raw material is weighed to a predetermined ratio, and then wet-mixed for a predetermined time using a ball mill or the like. After the mixed powder is dried, it is heat-treated at 1000 ° C. or lower in the air to obtain a calcined powder of the composite oxide.

Subsequently, the calcined powder obtained above is made into a paint to prepare a paste for a dielectric layer. The paste for the dielectric layer may be an organic paint obtained by kneading a mixed dielectric powder and an organic vehicle, or may be a water-based paint.

An organic vehicle is a binder dissolved in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from various ordinary binders such as ethyl cellulose and polyvinyl butyral. The organic solvent to be used is not particularly limited, and various organic solvents such as terpineol, butyl carbitol, and acetone may be appropriately selected depending on the method to be used such as a printing method and a sheet method.

When the paste for the dielectric layer is used as a water-based paint, the water-based vehicle in which a water-soluble binder, a dispersant, or the like is dissolved in water may be kneaded with the dielectric material. The water-soluble binder used in the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, a water-soluble acrylic resin, or the like may be used.

The paste for the internal electrode layer is obtained by kneading the above-mentioned various conductive metals, a conductive material made of an alloy thereof, various oxides, an organometallic compound, a resinate, etc., which become the above-mentioned conductive material after firing, and the above-mentioned organic vehicle. To prepare.

The paste for the external electrode may be prepared in the same manner as the paste for the internal electrode layer described above.

The content of the organic vehicle in each of the above-mentioned pastes is not particularly limited, and may be a normal content, for example, about 1% by mass to 5% by mass for the binder and about 10% by mass to 50% by mass for the solvent. Further, each paste may contain an additive selected from various dispersants, plasticizers, dielectrics, insulators and the like, if necessary. The total content of these is preferably 10% by mass or less.

When the printing method is used, the paste for the dielectric layer and the paste for the internal electrode layer are printed and laminated on a substrate such as PET, cut into a predetermined shape, and then peeled from the substrate to obtain a green chip.

When the sheet method is used, a green sheet is formed using the paste for the dielectric layer, the paste for the internal electrode layer is printed on the green sheet, and then these are laminated to form a green chip.

Before firing, the green chips are debindered. As the binder removal conditions, the temperature rising rate is preferably 5 ° C./hour to 300 ° C./hour, the holding temperature is preferably 180 ° C. to 500 ° C., and the temperature holding time is preferably 0.5 hour to 24 hours. The atmosphere is air or a reducing atmosphere. Further, in the above binder removal processing, to wet the N ₂ gas and mixed gas, etc., for example, it may be used to wetter like. In this case, the water temperature is preferably about 5 ° C. to 75 ° C.

The holding temperature during firing is preferably 1250 ° C to 1450 ° C, more preferably 1300 ° C to 1400 ° C. If the holding temperature is less than the above range, the densification of the sintered body becomes insufficient, and if it exceeds the above range, the electrode is likely to be interrupted due to abnormal sintering of the internal electrode layer, and the material constituting the internal electrode layer. The rate of change of capacitance with respect to temperature tends to be large due to the diffusion of. Further, if it exceeds the above range, the crystal particles may become coarse and the insulating property of the sintered body may be deteriorated.

The rate of temperature rise is preferably 200 ° C./hour to 1000 ° C./hour, and more preferably 200 ° C./hour to 500 ° C./hour. Further, in order to control the particle size distribution of the crystal particles after sintering within the range of 0.5 μm to 5.0 μm, the temperature holding time is preferably 1.0 hour to 24.0 hours, more preferably 2.0. The cooling rate is preferably 100 ° C./hour to 500 ° C./hour, more preferably 200 ° C./hour to 300 ° C./hour.

Further, as the firing atmosphere, it is preferable _{to use a mixed gas of humidified N 2} and H ₂ and to have an oxygen partial pressure of ^10-2 to ^{10-9 Pa.} More preferably, the oxygen partial pressure is ^10-2 to ^10-5 Pa.

After firing, the obtained element body is annealed as necessary. The annealing treatment conditions may be known conditions. For example, it is preferable that the oxygen partial pressure during the annealing treatment is higher than the oxygen partial pressure during firing and the holding temperature is 1000 ° C. or lower.

Further, the above-mentioned debinder treatment, firing and annealing treatment may be performed independently or continuously.

The composite oxide contained in the dielectric layer of the sintered body (device body) obtained as described above is represented by the above-mentioned composition formula and has a rutile-type crystal structure. The sintered body is subjected to end face polishing by, for example, barrel polishing or sandblasting, and an external electrode paste is applied and fired to form an external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

(3. Effect in this embodiment)
In the present embodiment, as the composite oxide constituting the dielectric composition _{, not only a part of titanium (Ti) of titanium dioxide (TiO 2} ) is replaced with an acceptor element and a donor element, but also the same valence as Ti. The element having (+4 valent element) also replaces a part of Ti.

Then, by controlling the total substitution amount (x + y + z) of the substitution element and the ratio of the acceptor amount (x) and the donor amount (z) within a predetermined range, it is caused by the defect dipole mechanism utilizing oxygen defects. It is possible to develop a very large relative permittivity.

Further, the total substitution amount (x + y + z) of the substitution element, the total amount of the acceptor amount (x) and the donor amount (z), and the ratio of the substitution amount (y) of the + tetravalent element are controlled within a predetermined range. As a result, an interaction occurs between the acceptor (A), the donor (C), and the + tetravalent element (B), and the effect of pinning the electron can be strengthened. As a result, it is possible to suppress a decrease in specific resistance even under a high electric field strength when a DC voltage is applied. In other words, the voltage dependence of the resistivity can be reduced.

That is, in TiO ₂ , a part of Ti is replaced by an element belonging to three element groups (A, B and C) classified by the difference in valence, and the relationship of the amount of substitution of the element belonging to the three element groups is established. with the range described above, very high dielectric constant (e.g., 10,000 or more) while exhibiting a high specific resistance (e.g. under high electric field strength, 5V / μm 1.00 × 10 ⁸ in an electric field strength of Ωcm or more) can be obtained.

Since the electric field strength is proportional to the applied voltage, the fact that the dielectric composition according to the present embodiment can obtain a high resistivity under a high electric field strength means that the electrons including the dielectric layer containing the dielectric composition are provided. This leads to an increase in the rated voltage of the parts. Therefore, such an electronic component can be used even when a high voltage exceeding the rated voltage of the conventional electronic component is applied, and more electric charge can be accumulated.

Furthermore, by further limiting the relationship between the substitution amounts of the elements belonging to the three element groups, it is possible to further increase the specific resistance under high electric field strength while maintaining a very high relative permittivity.

(4. Modification example)
In the above-described embodiment, the case where the electronic component is a multilayer ceramic capacitor has been described, but the electronic component may be another electronic component, for example, a thin film capacitor. In this case, the dielectric layer of the thin film capacitor may be composed of the above-mentioned dielectric composition. The dielectric layer of this thin film capacitor may be formed by depositing the elements constituting the above-mentioned dielectric composition on the substrate by using, for example, a thin film forming method or the like. As the thin film forming method, a known vapor phase growth method such as a sputtering method or a chemical vapor deposition method is preferable.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and may be modified in various ways within the scope of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

First, as starting materials of the complex oxide as the main component of the dielectric composition _{(Ti 1.0000-x-y-} z A x B y C z O 2 + δ), titanium dioxide _(TiO 2), "A" Powders of oxide (A ₂ O ₃ ), oxide of "B" (BO ₂ ) and oxide of "C" (C ₂ O ₅ ) were prepared. The average particle size of each powder was 1.0 μm or less. The above starting materials were weighed so that the dielectric composition (sintered body) after the main firing had the compositions shown in Tables 1 and 2.

Next, each of the weighed raw material powders was wet-mixed with a ball mill for 16 hours using ethanol as a dispersion medium, and the mixture was dried to obtain a mixed raw material powder. Then, the obtained mixed raw material powder was heat-treated in the air under the conditions of a holding temperature of 950 ° C. and a holding time of 24 hours to obtain a calcined powder of a composite oxide.

To 1000 g of the calcined powder obtained above, 700 g of a solvent obtained by mixing a toluene + ethanol solution, a plasticizer and a dispersant at a ratio of 90: 6: 4 was added, and using a basket mill, which is a well-known dispersion method, 2 The paste was dispersed for a time to prepare a paste for a dielectric layer.

As a raw material for the internal electrode layer, Ni powder having an average particle size of 0.2 μm was prepared, and 100% by mass of Ni powder and 30% by mass of an organic vehicle (8% by mass of ethyl cellulose resin dissolved in 92% by mass of butyl carbitol) were prepared. % And 8% by mass of butyl carbitol were kneaded and made into a paste by three rolls to obtain a paste for the internal electrode layer. The viscosity of each of these pastes was adjusted to about 200 cps.

Using the prepared paste for the dielectric layer, a green sheet was formed on the PET film so that the thickness after drying was 7 μm. Next, the internal electrode layer was printed in a predetermined pattern using the paste for the internal electrode layer, and then the sheet was peeled off from the PET film to prepare a green sheet having the internal electrode layer. Next, a plurality of green sheets having an internal electrode layer were laminated and pressure-bonded to form a green laminate, and the green laminate was cut to a predetermined size to obtain a green chip.

Next, the obtained green chips were subjected to a binder removal treatment, a firing treatment, and an annealing treatment to obtain a laminated ceramic sintered body. The conditions for the binder removal treatment, firing and annealing treatment are as follows. A wetter was used to humidify each atmospheric gas.
(Binder removal processing)
Temperature rise rate: 100 ° C / hour Holding temperature: 400 ° C
Temperature holding time: 8.0 hours Atmospheric gas: Mixed gas of _{humidified N 2} and H _{2 (firing)}
Temperature rise rate: 300 ° C / hour Holding temperature: 1300 ° C to 1450 ° C
Temperature holding time: 10 hours Cooling rate: 200 ° C./hour Atmospheric gas: _{Mixed gas of humidified N 2} and H ₂ Oxygen partial pressure: ^10-2 to ^10-5 Pa
(Annealing process)
Holding temperature: 1000 ° C
Temperature holding time: 2.0 hours temperature rise, temperature decrease rate: 200 ° C / hour Atmospheric gas: Humidified N ₂ gas

Tables 1 and 2 show the results of composition analysis of the dielectric composition contained in each of the obtained sintered bodies (element body) using ICP emission spectroscopic analysis. Consistent with composition.

After polishing the end face of the obtained sintered body by sandblasting, an In—Ga eutectic alloy is applied as an external electrode, and a laminated ceramic capacitor sample having the same shape as the laminated ceramic capacitor shown in FIG. 1 (from sample No. 1). Sample No. 54) was obtained. The size of each of the obtained multilayer ceramic capacitor samples is 3.2 mm × 1.6 mm × 1.2 mm, the thickness of the dielectric layer is 5.0 μm, the thickness of the internal electrode layer is 2.0 μm, and the internal electrode layer has a thickness of 2.0 μm. The number of sandwiched dielectric layers was 50.

The obtained sample No. Sample No. 1 to sample No. For 54 multilayer ceramic capacitor samples, the relative permittivity at room temperature, tan δ, and the specific resistance when a DC voltage of 25 V (electric field strength 5 V / μm) was applied were measured and evaluated as follows.

[Relative permittivity and tan δ]
A signal with a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms is input to a multilayer ceramic capacitor sample at room temperature (20 ° C.) with a digital LCR meter (4284A manufactured by YHP), and the capacitance and tan δ are measured. did. Then, the relative permittivity (without unit) was calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance obtained by the measurement. It was judged that a high relative permittivity was preferable and 10,000 or more was good, and a low tan δ was preferably 30% or less. The results are shown in Tables 1 and 2.

[Specific resistance when DC voltage is applied]
A measurement voltage of 25 V (electric field strength 5 V / μm) is applied to a multilayer ceramic capacitor sample at room temperature (20 ° C.) with a digital resistance meter (R8340 manufactured by ADVANTEST), and insulation resistance is applied under the condition of a measurement time of 60 seconds. It was measured. For reference, the insulation resistance when the measured voltage was 5 V (electric field strength 1 V / μm) was also measured in the same manner.

The value of specific resistance was calculated from the obtained insulation resistance, the electrode area of the monolithic ceramic capacitor sample, and the thickness of the dielectric. The specific resistance the higher is preferable, in the measurement voltage 25V (field strength 5V / [mu] m), was determined sample is 1.00 × 10 ⁸ Ωcm or more and is good. Samples specific resistance is 1.00 × 10 ⁹ Ωcm or more is more preferable. In Tables 1 and 2, the value of the specific resistance is displayed logarithmically, and when it is represented by "a" in the column of the specific resistance in Tables 1 and 2, the value of the specific resistance is 10 ^a . 1.00 × 10 ⁹ to when logarithm 9.0 next, when the 3.16 × 10 ⁸ to logarithm, 8.5, and becomes 8.0 when the 1.00 × 10 ⁸ to logarithm. The results are shown in Tables 1 and 2.

According to the results shown in Tables 1 and 2, the sample No. 1-Sample No. Of 54, it has been confirmed that in the multilayer ceramic capacitor sample within the range of the present embodiment, defective dipoles utilizing oxygen defects are formed, so that a huge relative permittivity of 10,000 or more and a low dielectric loss can be obtained. did it. Further, the amount of substitution (acceptor amount) of +3 valent elements (Al, Ga, In, rare earth elements), the amount of substitution (donor amount) of +5 valent elements (V, Nb, Sb, Ta), and +4 valent elements (Si). , Zr, Hf) due to a predetermined relationship with the substitution amount, it is possible to suppress the movement of oxygen defects and enhance the effect of pinning electrons. As a result, even in a high electric field intensity (5V / [mu] m), it was confirmed to exhibit a high specific resistance (1.00 × 10 ⁸ Ωcm or higher).

On the other hand, sample No. 1-Sample No. 6, formula _{Ti 1.0000-x-y-z} A x B y C z O 2 + δ x in a y, or one of z is 0, outside the scope of this embodiment. In this case, a very large relative permittivity due to a defective dipole utilizing oxygen defects does not appear, or the amount of substitution of the +3 valent element "A" (Al, Ga, In, rare earth element) and +5. No interaction is obtained due to the predetermined relationship between the substitution amount of the valence element "C" (V, Nb, Sb, Ta) and the substitution amount of the +4 valence element "B" (Si, Zr, Hf). As a result, the dielectric constant becomes less than 10000, or the specific resistance under high electric field intensity (5V / μm) it was confirmed that less than 1.00 × 10 ⁸ Ωcm.

In addition, sample No. 7. Sample No. In No. 8, since the total substitution amount (x + y + z) of "A", "B" and "C" is outside the range of this embodiment, it is difficult to obtain the action of a defective dipole utilizing oxygen defects, and the relative permittivity is high. It was confirmed that it was less than 10,000.

Further, the sample No. in which the ratio ((x + z) / y) of the total amount of the substitution amount of “A” and the substitution amount of “C” to the substitution amount of “B” is outside the range of the present embodiment. 9. Sample No. 11. Sample No. 13. Sample No. 22, Sample No. In No. 23, although the +4 valent element "B" replaces a part of Ti, the amount of substitution of the +3 valent element "A" (Al, Ga, In, rare earth element) and the +5 valent element "C" (V) , Nb, Sb, Ta) and the substitution amount of the +4 valent element "B" (Si, Zr, Hf) could not be interacted with due to the predetermined relationship, and under high electric field strength (5V /). resistivity in [mu] m) it was confirmed that less than 1.00 × 10 ⁸ Ωcm.

Further, the sample No. in which the ratio (x / z) of the acceptor amount and the donor amount is less than 0.8000. 11. Sample No. 19, tan [delta exceeds 30%, the specific resistance under high electric field intensity (5V / μm) it was confirmed that less than 1.00 × 10 ⁸ Ωcm. On the other hand, the sample No. in which x / z exceeds 1.2000. 8. Sample No. 9. Sample No. It was confirmed that No. 18 showed a very low relative permittivity of less than 1000.

In addition, sample No. 1-Sample No. Of the 54, in the multilayer ceramic capacitor sample within the range of the present embodiment, if the acceptor "A" is one or more elements selected from Al, Ga, In and rare earth elements, the relative permittivity is 10,000. while exhibiting higher, specific resistance under high electric field intensity (5V / μm) was confirmed to be at 1.00 × 10 ⁸ Ωcm or more. Similarly, the +4 valent element "B" may be one or more elements selected from Si, Zr, Hf, and the donor "C" may be one or more elements selected from V, Nb, Sb, Ta. For example, it was confirmed that the same effect can be obtained.

The sample No. in which the ratio (x / z) of the acceptor amount to the donor amount is in the range of 1.0200 <x / z ≦ 1.2000. 16. Sample No. 25, Sample No. 31, Sample No. 33-Sample No. 38 further can be enhanced and made effective to pin the movement restraining and electrons of the oxygen defects, under high electric field intensity (5V / [mu] m), a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) give It was confirmed that it was easy to get rid of.

The ratio (x / z) of the acceptor amount to the donor amount is 0.8000 ≦ x / z <0.9800, and (x + z) / y satisfies 2.000 ≦ (x + z) / y ≦ 9.0000. Sample No. 17, Sample No. 48-Sample No. 50, sample No. 52 ~ Sample No. 54 also, since it is possible to further enhance the effect of pinning the movement restraining and electrons of the oxygen defects, under high electric field intensity (5V / [mu] m), a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) Was confirmed to be easy to obtain.

The ratio (x / z) of the acceptor amount to the donor amount is 0.9800 ≦ x / z ≦ 1.0200, and (x + z) / y satisfies 7.0000 <(x + z) / y <17.0000. Sample No. 21, Sample No. 24, Sample No. 32, Sample No. 40-Sample No. 45 also, since it is possible to enhance the effect of pinning the movement restraining and electrons of the oxygen defect Furthermore, under high electric field strength at (5V / [mu] m), a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) Was confirmed to be easy to obtain.

The dielectric composition according to the present invention, high dielectric constant (e.g., 10,000 or more) and a high specific resistance under high field strengths (e.g., at ^{5V / μm, 1.00 × 10 8} Ωcm or higher) and the Since they are compatible with each other, they can be suitably used as a dielectric layer of electronic components such as a compact and large-capacity multilayer ceramic capacitor and a low-profile and large-capacity thin film capacitor.

1 ... Multilayer ceramic capacitor 10 ... Element body 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode

Claims (5)

Expressed by a composition formula _{Ti 1.0000-x-y-z} A x B y C z O 2 + δ, comprise a composite oxide having a rutile-type crystal structure as a main component,
One or more elements in which A is selected from the group consisting of Al, Ga, In and rare earth elements,
One or more elements, wherein B is selected from the group consisting of Si, Zr and Hf.
C is one or more elements selected from the group consisting of V, Nb, Sb and Ta.
The x, the y, and the z
x> 0, y> 0, z> 0,
0.0050 ≦ x + y + z ≦ 0.3000,
2.0000 ≦ (x + z) / y ≦ 20.0000,
0.8000 ≤ x / z ≤ 1.2000
Satisfied with the relationship
Ri der dielectric constant of 14500 or more at a frequency 1 kHz, tan [delta is 30% or less at a frequency 1 kHz, a dielectric resistivity at the electric field intensity 5V / [mu] m is characterized der Rukoto 1.00 × 10 ⁸ Ωcm or higher Body composition. The dielectric composition according to claim 1, wherein the x and the z satisfy a relationship of 1.0200 <x / z ≦ 1.2000. The x, the y, and the z
0.8000 ≤ x / z <0.9800,
2.0000 ≦ (x + z) / y ≦ 9.0000
The dielectric composition according to claim 1, wherein the dielectric composition is characterized by satisfying the relationship. The x, the y, and the z
0.9800 ≤ x / z ≤ 1.0200,
7.0000 <(x + z) / y <17.0000
The dielectric composition according to claim 1, wherein the dielectric composition is characterized by satisfying the relationship. An electronic component comprising a dielectric layer containing the dielectric composition according to any one of claims 1 to 4.

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