JP2018118878A - Dielectric composition and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric composition which has high resistivity under a high electric field strength during direct voltage impression while showing a high dielectric constant, and to provide electronic components including a dielectric layer formed with the dielectric composition.SOLUTION: A dielectric composition comprises mainly a complex oxide expressed by composition formula, TiABCO, and having a rutile type crystal structure, wherein: A is one or more element selected from the group consisting of Al, Ga, In and a rare-earth element; B is one or more element selected from the group consisting of Si, Zr, and Hf; C is one or more element selected from the group consisting of V, Nb, Sb and Ta; and x, y and z satisfies relations of 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.SELECTED DRAWING: None

Description

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

  As electronic components such as multilayer ceramic capacitors and thin film capacitors become smaller and have higher functionality, dielectric materials used for these dielectric layers include materials that exhibit a high relative dielectric constant and a low dielectric loss. Desired. Furthermore, since the DC voltage is applied to the electronic component during the operation of the electronic device in which these electronic components are mounted, the insulation of the dielectric layer is maintained even under a high electric field strength caused by the DC voltage. There is a need.

At present, the relative dielectric constant of BaTiO ₃ -based dielectric compositions widely used as dielectric materials is about 500 to 6000, and the relative dielectric constant hardly exceeds 10,000.

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

Patent Document 2 discloses a dielectric material in which Nb ₂ O ₅ is contained in TiO ₂ as a main component to make it a semiconductor and Bi ₂ O ₃ , CeO ₂ , and La ₂ Ti ₂ O ₇ are further contained. It is disclosed that this dielectric material also has both a huge relative dielectric constant exceeding 10,000 and low dielectric loss.

Special table 2014-531389 gazette JP-A-55-95204

  However, in the dielectric material described in Patent Document 1, since electrons are localized (pinned) using oxygen defects, a high DC voltage is applied to an electronic component including a dielectric layer using the dielectric material. When is applied, oxygen vacancies are easily moved, and localized electrons are easily hopped and the specific resistance is abruptly reduced.

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

The present invention has been made in view of such a situation, and an object of the present invention is to exhibit a high specific resistance (for example, 5V / It is an object of the present invention to provide an electronic component including a dielectric composition having a thickness of 1.00 × 10 ⁸ Ωcm or more in μm and a dielectric layer composed of the dielectric composition.

In order to achieve the above object, the dielectric composition of the present invention comprises:
[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 selected from the group consisting of Al, Ga, In and rare earth elements,
One or more elements selected from the group consisting of B, 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
A dielectric composition characterized by satisfying the following relationship:

  [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 satisfies the following relationship:

[4] x, y and z are
0.9800 ≦ x / z ≦ 1.0200,
7.00 <(x + z) / y <17.0000
The dielectric composition according to [1], which satisfies the following relationship:

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

Since the dielectric composition of the present invention has the above characteristics, it exhibits a high specific resistance (for example, 5 V / μm) even under a high electric field strength when a DC voltage is applied while exhibiting a high relative dielectric constant (for example, 10,000 or more). In addition, it is possible to provide an electronic component including a dielectric composition having 1.00 × 10 ⁸ Ωcm or more) and a dielectric layer composed of the dielectric composition.

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. Multilayer Ceramic Capacitor 1.1 Overall Configuration of Multilayer Ceramic Capacitor 1.2 Dielectric Layer 1.2.1 Dielectric Composition 1.3 Internal Electrode Layer 1.4 Terminal Electrode 2. 2. Manufacturing method of multilayer ceramic capacitor Effect in the present embodiment 4. Modified example

(1. Multilayer ceramic capacitor)
(1.1 Overall structure of multilayer ceramic capacitor)
As shown in FIG. 1, a multilayer ceramic capacitor 1 as an example of an electronic component according to this embodiment includes an element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. At both ends of the element body 10, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. Although there is no restriction | limiting in particular in the shape of the element main body 10, Usually, it is set as a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

(1.2 Dielectric layer)
The dielectric layer 2 is comprised from the dielectric composition which concerns on this embodiment mentioned later. As a result, the multilayer ceramic capacitor having the dielectric layer 2 exhibits a high specific resistance (for example, 5 V / μm) while exhibiting a high relative dielectric constant (for example, 10,000 or more) and a high electric field strength when a DC voltage is applied. 1.00 × 10 ⁸ Ωcm or more).

  The thickness per layer of the dielectric layer 2 (interlayer thickness) is not particularly limited, and can be arbitrarily set according to desired characteristics and applications. 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 about 3.0 μm, for example, but it may be thinner than this. According to the dielectric composition according to the present embodiment, the above-described effects can be sufficiently obtained even when the interlayer thickness is in the above range.

  Further, the number of stacked 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 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 structure substituted with an element. In the composite oxide, the oxygen (O) amount 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, 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 that is 1 less than the valence of Ti (+4). 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 at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. . Thus, “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 selected.

  “X” in the above composition formula represents the ratio (acceptor amount) of “A” replacing Ti in the composite oxide. In the present embodiment, x> 0 and 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 that of Ti (+4 valence). Specifically, “B” is one or more selected from the group consisting of Si, Zr, and Hf, and preferably includes at least Zr.

  “Y” in the above composition formula indicates the ratio (B substitution amount) of “B” substituting Ti in the composite oxide. In the present embodiment, y> 0 and 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 which is 1 greater than the valence of Ti (+4). 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 includes at least Nb.

  “Z” in the above composition formula indicates a ratio (donor amount) of “C” replacing Ti in the composite oxide. In the present embodiment, z> 0 and preferably 0.0010 or more. The upper limit of “z” is determined by the relationship between “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. (Ti is replaced). “X”, “y”, and “z”, that is, the substitution amount of “A” (acceptor amount) with respect to Ti, the substitution amount of “B”, and the substitution amount of “C” (donor amount) have a predetermined relationship. By controlling to satisfy the above, a very high dielectric constant (for example, 10,000 or more) and 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 elements substituting Ti (“A”, “B” and “C”), the ratio of the substitution amount of “B” to the total amount of acceptor and donor, the amount of acceptor and donor The ratio with the amount is controlled. In this embodiment, the total substitution amount satisfies the relationship of 0.0050 ≦ x + y + z ≦ 0.3000, and the ratio of the substitution amount of “B” to the total of the acceptor amount and the donor amount is 2.0000 ≦ ( x + z) /y≦20.0000 is satisfied, and the relationship between the acceptor amount and the donor amount is 0.8000 ≦ x / z ≦ 1.2000.

  In the present embodiment, the total substitution amount and the ratio of the substitution amount of “B” to the total of the acceptor amount and the donor amount are within the above range, so that the high substitution is also achieved under a high electric field strength when a DC voltage is applied. Specific resistance can be obtained. On the other hand, when the ratio of the total substitution amount and the substitution amount of “B” to the total of the acceptor amount and the donor amount does not satisfy the above relationship, the resistivity decreases rapidly when a high DC voltage is applied. There is a tendency.

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

  Therefore, in order to achieve both a very high dielectric constant and a high specific resistance under a high electric field strength when a DC voltage is applied, the total substitution amount of elements substituting Ti, the substitution amount of B, the acceptor amount, and the donor amount And the ratio of the amount of acceptor to the amount of donor must all satisfy the above relationship.

For example, the following explanation is possible as a factor for obtaining a very high dielectric constant. That is, a part of Ti of TiO ₂ having a rutile crystal structure is negatively charged by substituting +5 valent element “C” (at least one selected from V, Nb, Sb, Ta) as a donor. Electrons are generated. However, when only the donor is introduced, usually, the hopping conduction of electrons is promoted, so that the specific resistance is lowered.

Therefore, a positively charged oxygen defect is further obtained by substituting a part of Ti of TiO ₂ with an acceptor + trivalent element “A” (at least one selected from Al, Ga, In and rare earth elements). And the electrons generated by the generated oxygen defects are pinned. As a result, the movement of electrons is suppressed, so that a decrease in specific resistance can be suppressed. At this time, since the generated electrons move between the lattices of Ti-Ti within the range of the pinning effect due to oxygen defects, defect dipoles using oxygen defects are formed, and a huge amount due to the presence of defect dipoles is formed. It becomes possible to obtain a relative dielectric constant.

  Moreover, as a factor which can obtain a high specific resistance under the high electric field strength at the time of DC voltage application, it can estimate as follows, for example. Oxygen vacancies generated by introduction of the acceptor are easily moved when a high DC voltage is applied, and the influence of the pinning effect is reduced for the pinned electrons, and the hopping conduction of the electrons easily occurs. For this reason, specific resistance falls rapidly under a high DC voltage.

In the present embodiment, in order to suppress an abrupt decrease in resistivity, Ti +4 valence element "B" having the same valence as (Si, Zr, at least one selected from Hf) in the TiO ₂ of Ti Substituting a part, and controlling the substitution amount (acceptor amount) of + trivalent element “A”, the substitution amount (donor amount) of +5 valent element “C”, and the substitution amount of +4 valent element “B” Thus, the interaction between these elements can suppress the movement of oxygen vacancies and strengthen the effect of pinning electrons, and the decrease in specific resistance 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 into 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 generated. 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-described range, a high specific permittivity and a high specific resistance under a high electric field strength when a DC voltage is applied are obtained. It can be compatible.

  In the present embodiment, it is preferable that x and z satisfy the relationship of 1.0200 <x / z ≦ 1.2000. That is, by making the above-mentioned range (“A” rich range) in which the substitution amount (acceptor amount) of “A” is larger than the substitution amount (donor amount) of “C”, the migration of oxygen defects and electrons are reduced. It is possible to further strengthen the effect of pinning. 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, x, y, and z have the relationship of 2.0000 ≦ (x + z) /y≦9.0000. It is preferable to satisfy. That is, when the substitution amount (acceptor amount) of “A” is in the above range (“C” rich range) smaller than the substitution amount (donor amount) of “C”, the substitution amount (acceptor amount) of “A” ) And the substitution amount (donor amount) of “C” and the substitution amount (+ tetravalent element amount) of “B” within the above range, thereby suppressing the migration of oxygen defects and electrons. It is possible to further strengthen the effect of pinning. As a result, a higher specific resistance tends to be easily obtained under a high electric field strength when a DC voltage is applied.

  When x and z satisfy the relationship of 0.9800 ≦ x / z ≦ 1.0200, x, y and z satisfy the relationship of 7.0000 <(x + z) / y <17.0000. It is preferable to satisfy. That is, when the substitution amount (acceptor amount) of “A” and the substitution amount (donor amount) of “C” are within the same range, the substitution amount (acceptor amount) of “A” and “C” By making the ratio of the total amount of the substitution amount (donor amount) and the substitution amount (+ tetravalent element amount) of “B” in the above range, the effect of suppressing the migration of oxygen defects and pinning electrons 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 dielectric constant 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 and large-capacity thin film capacitor.

  In addition, the dielectric composition according to the present embodiment may contain a trace amount of impurities, subcomponents, and the like within a range where the effects of the present invention are exhibited. Examples of such components 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 each end face is alternately exposed on the surface of the two opposite ends of the element body 10.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni, Ni-based alloy, Cu or Cu-based alloy is preferable. In addition, in Ni, Ni-type alloy, Cu, or Cu-type alloy, various trace components, such as P, may be contained about 0.1 mass% or less. The internal electrode layer 3 may be formed using a commercially available electrode paste. What is necessary is just to determine the thickness of the internal electrode layer 3 suitably according to a use etc.

(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 connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit. The conductive material contained in the external electrode 4 is not particularly limited. In the present embodiment, various conductive materials such as inexpensive Ni, Cu, high heat-resistant Au, Ag, Pd, and alloys thereof can be used. The thickness of the external electrode 4 may be determined as appropriate according to 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.

  In the multilayer ceramic capacitor 1 according to the present embodiment, a green chip is produced by a normal printing method or a sheet method using a paste as in the case of a conventional multilayer ceramic capacitor, and this is fired to obtain an element body. It is manufactured by printing or transferring an external electrode on the element body and baking 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, a mixture thereof, or a composite oxide included in the composite oxide constituting the dielectric composition can be used. In addition, various compounds that are converted into the above-described oxides or composite oxides by firing, such as carbonates, oxalates, nitrates, hydroxides, organometallic compounds, and the like, can be appropriately selected and mixed for use. For example, when “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 are prepared. Good. In addition, it is preferable that the average particle diameter of each powder is 1.0 micrometer or less.

  The prepared starting materials are weighed at a predetermined ratio, and then wet mixed using a ball mill or the like for a predetermined time. After drying the mixed powder, heat treatment at 1000 ° C. or lower is performed in the air to obtain a calcined powder of a composite oxide.

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

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. The organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone and the like according to a method to be used such as a printing method or a sheet method.

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

  The internal electrode layer paste is a mixture of the above-described various conductive metals, conductive materials made of alloys thereof, or various oxides, organometallic compounds, resinates, and the like that become the conductive materials described above after firing, and the above-described organic vehicle. To prepare.

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

  There is no restriction | limiting in particular in content of the organic vehicle in each above-mentioned paste, For example, what is necessary is just about 1 mass%-about 5 mass% for a binder, and about 10 mass%-about 50 mass% for a solvent. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these is preferably 10% by mass or less.

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste 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 dielectric layer paste is used to form a green sheet, the internal electrode layer paste is printed thereon, and these are stacked to form a green chip.

Before firing, the green chip is subjected to binder removal processing. As binder removal conditions, the rate of temperature rise 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 hours to 24 hours. The atmosphere is air or a reducing atmosphere. Further, in the above-described binder removal process, for example, a wetter or the like may be used to wet the N ₂ gas, mixed gas, or the like. In this case, the water temperature is preferably about 5 ° C to 75 ° C.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1250 degreeC-1450 degreeC, More preferably, it is 1300 degreeC-1400 degreeC. If the holding temperature is less than the above range, densification of the sintered body becomes insufficient, and if it exceeds the above range, the electrode is likely to be disconnected 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 is likely to increase due to the diffusion of. In addition, if the above range is exceeded, the crystal grains may be coarsened and the insulating properties of the sintered body may be reduced.

  The rate of temperature rise is preferably 200 ° C./hour to 1000 ° C./hour, more preferably 200 ° C./hour to 500 ° C./hour. In order to control the particle size distribution of the sintered crystal particles 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.

As the firing atmosphere, a mixed gas of wet _{N 2} and _{H 2,} it is preferable oxygen partial pressure is ¹⁰ -2 ^~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 conditions may be known conditions. For example, it is preferable that the oxygen partial pressure during the annealing process is higher than the oxygen partial pressure during firing, and the holding temperature is 1000 ° C. or lower.

  Moreover, said binder removal process, baking, and annealing treatment may be performed independently, and may be performed continuously.

  The composite oxide contained in the dielectric layer of the sintered body (element body) obtained as described above is represented by the composition formula described above and has a rutile crystal structure. The sintered body is subjected to end face polishing by, for example, barrel polishing or sand blasting, and an external electrode paste is applied and fired to form the 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. Effects in the present embodiment)
In this embodiment, as a composite oxide constituting the dielectric composition, not only a part of titanium (Ti) of titanium dioxide (TiO ₂ ) is replaced by an acceptor element and a donor element, but also the same valence as Ti. An element having (a tetravalent element) also substitutes 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) to a predetermined range, the defect is caused by a defect dipole mechanism using oxygen defects. It is possible to develop a very large relative dielectric constant.

  Furthermore, the total substitution amount (x + y + z) of the substitution element, and the ratio of the total amount of the acceptor amount (x) and the donor amount (z) and 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 + 4-valent element (B), and the effect of pinning electrons can be increased. 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 dependency of the specific resistance can be reduced.

That is, in TiO ₂ , a part of Ti is replaced with an element belonging to three element groups (A, B and C) divided by the difference in valence, and the relationship between the substitution amounts of elements belonging to the three element groups is By setting it within the above-described range, a high specific resistance (for example, 1.00 × 10 ⁸ under an electric field strength of 5 V / μm) while exhibiting a very high relative dielectric constant (for example, 10,000 or more) and a high electric field strength. 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 has a high specific resistance under a high electric field strength means that an electron including a dielectric layer containing the dielectric composition is provided. It leads to raising the rated voltage of 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 charges can be accumulated.

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

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

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment at all, You may modify | change in various aspects 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" Oxide (A ₂ O ₃ ), “B” oxide (BO ₂ ) and “C” oxide (C ₂ O ₅ ) powders 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 weighed raw material powder was wet mixed for 16 hours by a ball mill using ethanol as a dispersion medium, and the mixture was dried to obtain a mixed raw material powder. Thereafter, the obtained mixed raw material powder was heat-treated in the atmosphere 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 90: 6: 4 was added, and 2 using a basket mill which is a well-known dispersion method. Dispersion with time was performed to prepare a dielectric layer paste.

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

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

Next, the obtained green chip was subjected to binder removal processing, firing and annealing treatment to obtain a multilayer ceramic sintered body. The conditions for the binder removal treatment, firing and annealing treatment are as follows. Moreover, a wetter was used for humidifying each atmospheric gas.
(Binder removal)
Temperature increase rate: 100 ° C / hour Holding temperature: 400 ° C
Temperature holding time: 8.0 hours Atmospheric gas: Mixed gas of N ₂ and H ₂ humidified (firing)
Temperature rising 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 treatment)
Holding temperature: 1000 ° C
Temperature holding time: 2.0 hours temperature rise, temperature drop rate: 200 ° C./hour Atmosphere gas: humidified N ₂ gas

  The obtained sintered bodies (element main bodies) were analyzed in terms of the composition of the dielectric composition contained in each sintered body using ICP emission spectroscopy, and are listed in Tables 1 and 2. Consistent with composition.

  After polishing the end face of the obtained sintered body by sand blasting, an In—Ga eutectic alloy was applied as an external electrode, and a multilayer ceramic capacitor sample having the same shape as the multilayer ceramic capacitor shown in FIG. Sample No. 54) was obtained. The size of each obtained multilayer ceramic capacitor sample 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, The number of the dielectric layers sandwiched was 50 layers.

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

[Relative permittivity and tan δ]
A multilayer ceramic capacitor sample was input at a room temperature (20 ° C) with a digital LCR meter (4284A manufactured by YHP) with a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms, and the capacitance and tan δ were measured. did. The relative dielectric constant (no unit) was calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance obtained by the measurement. The relative dielectric constant is preferably high, and it is judged that 10,000 or more is good, and tan δ is preferably low, and 30% or less is judged good. 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 of 5 V / μm) was applied to the multilayer ceramic capacitor sample at room temperature (20 ° C.) with a digital resistance meter (R8340 manufactured by ADVANTEST), and the insulation resistance was measured under the conditions of a measurement time of 60 seconds. It was measured. For reference, the insulation resistance when the measurement voltage was 5 V (electric field intensity 1 V / μm) was also measured.

The specific resistance value was calculated from the obtained insulation resistance, the electrode area of the multilayer ceramic capacitor sample, and the dielectric thickness. A higher specific resistance is preferable, and a sample having a measurement voltage of 25 V (electric field strength of 5 V / μm) of 1.00 × 10 ⁸ Ωcm or higher was judged to be good. A sample having a specific resistance of 1.00 × 10 ⁹ Ωcm or more is more preferable. In Tables 1 and 2, specific resistance values are logarithmically expressed. When “a” is shown in the specific resistance column of Tables 1 and 2, the specific resistance value is 10 ^a . The logarithmic display of 1.00 × 10 ⁹ is 9.0, and the logarithmic display of 3.16 × 10 ⁸ is 8.5, and the logarithmic display of 1.00 × 10 ⁸ is 8.0. The results are shown in Tables 1 and 2.

According to the results shown in Tables 1 and 2, sample no. 1 to Sample No. 54, it is confirmed that the multilayer ceramic capacitor sample within the scope of the present embodiment has a large relative dielectric constant of 10,000 or more and low dielectric loss because a defect dipole utilizing oxygen defects is formed. did it. Furthermore, the substitution amount (acceptor amount) of + trivalent elements (Al, Ga, In, rare earth elements), the substitution amount (donor amount) of +5 valent elements (V, Nb, Sb, Ta), and the + tetravalent element (Si) , Zr, Hf) due to the interaction with the predetermined amount of substitution, it is possible to suppress the movement of oxygen defects and enhance the effect of pinning electrons. As a result, it was confirmed that a high specific resistance (1.00 × 10 ⁸ Ωcm or more) was exhibited even under high electric field strength (5 V / μm).

In contrast, sample no. 1 to 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 dielectric constant due to a defect dipole utilizing oxygen defects does not appear, or a substitution amount of + trivalent element “A” (Al, Ga, In, rare earth element) and +5 The interaction resulting from the predetermined relationship between the substitution amount of the valent element “C” (V, Nb, Sb, Ta) and the substitution amount of the + 4-valent element “B” (Si, Zr, Hf) cannot be obtained. As a result, it was confirmed that the relative dielectric constant was less than 10,000, or the specific resistance under a high electric field strength (5 V / μm) was less than 1.00 × 10 ⁸ Ωcm.

  Sample No. 7, Sample No. No. 8, since the total substitution amount (x + y + z) of “A”, “B” and “C” is out of the range of this embodiment, it is difficult to obtain the effect of a defect dipole utilizing oxygen defects, and the relative dielectric constant is It was confirmed that it was less than 10,000.

In addition, the sample No. 1 in which the ratio ((x + z) / y) of the total amount of the substitution amount of “A” and the substitution amount of “C” and the substitution amount of “B” is out of the range of the present embodiment. 9, sample no. 11, Sample No. 13, Sample No. 22, Sample No. 23, although the + 4-valent element “B” replaces part of Ti, the substitution amount of the + 3-valent element “A” (Al, Ga, In, rare earth element) and the + 5-valent element “C” (V , Nb, Sb, Ta) and an interaction due to a predetermined relationship between the substitution amount of the + 4-valent element “B” (Si, Zr, Hf) cannot be obtained, and a high electric field strength (5 V / It was confirmed that the specific resistance in μm) was less than 1.00 × 10 ⁸ Ωcm.

In addition, the sample No. having a ratio (x / z) between the acceptor amount and the donor amount is less than 0.8000. 11, Sample No. 19, it was confirmed that tan δ exceeded 30% and the specific resistance under high electric field strength (5 V / μm) was less than 1.00 × 10 ⁸ Ωcm. On the other hand, Sample No. with x / z exceeding 1.2,000. 8, Sample No. 9, sample no. It was confirmed that No. 18 showed only a very low relative dielectric constant of less than 1000.

Sample No. 1 to Sample No. 54, in the multilayer ceramic capacitor sample within the scope of the present embodiment, if the acceptor “A” is one or more elements selected from Al, Ga, In and rare earth elements, the relative dielectric constant is 10,000. While showing the above, it was confirmed that the specific resistance under high electric field strength (5 V / μm) was 1.00 × 10 ⁸ Ωcm or more. Similarly, “B” which is a +4 valent element is one or more elements selected from Si, Zr and Hf, and “C” which is a donor is one or more elements selected from V, Nb, Sb and Ta. It was confirmed that the same effect can be obtained.

Sample No. in which the ratio of the acceptor amount to the donor amount (x / z) is in the range of 1.0200 <x / z ≦ 1.2000. 16, Sample No. 25, sample no. 31, sample no. 33 to Sample No. No. 38 can further enhance the effect of suppressing the movement of oxygen defects and pinning electrons, and a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) can be obtained under a high electric field strength (5 V / μm). It was confirmed that it was easy to be done.

The ratio (x / z) between the acceptor amount and 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 to Sample No. 50, sample no. 52-Sample No. 54 can further enhance the effect of suppressing the movement of oxygen defects and pinning electrons, so that it has a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) under a high electric field strength (5 V / μm). It was confirmed that it was easy to obtain.

The ratio (x / z) between the acceptor amount and 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 to Sample No. 45 can further enhance the effect of suppressing the movement of oxygen defects and pinning electrons, so that it has a higher specific resistance (1.00 × 10 ⁹ Ωcm or more) under a high electric field strength (5 V / μm). It was confirmed that it was easy to obtain.

The dielectric composition according to the present invention has a high relative dielectric constant (for example, 10,000 or more) and a high specific resistance under a high electric field strength (for example, 1.00 × 10 ⁸ Ωcm or more at 5 V / μm). Therefore, it can be suitably used as a dielectric layer of an electronic component such as a small-sized and large-capacity monolithic ceramic capacitor and a low-profile and large-capacity thin film capacitor.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Element main 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 selected from the group consisting of Al, Ga, In and rare earth elements,
One or more elements selected from the group consisting of Si, Zr and Hf,
The 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
A dielectric composition characterized by satisfying the relationship:   2. The dielectric composition according to claim 1, wherein the relationship between x and z is 1.0200 <x / z ≦ 1.2000. X, y and z are
0.8000 ≦ x / z <0.9800,
2.0000 ≦ (x + z) /y≦9.0000
The dielectric composition according to claim 1, wherein the following relationship is satisfied. X, y and z are
0.9800 ≦ x / z ≦ 1.0200,
7.00 <(x + z) / y <17.0000
The dielectric composition according to claim 1, wherein the following relationship is satisfied.   An electronic component comprising a dielectric layer containing the dielectric composition according to claim 1.

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