KR20200110244A - Dielectric composition and electronic component - Google Patents

Abstract

The present invention relates to a dielectric composition including a composite oxide represented by composition formula Bi_xZn_yNb_zO_1.75 + δ, wherein x, y, and z are satisfied with a relationship of x + y + z = 1.00, x < 0.20, 0.20 <= y <= 0.50, and 0.25 <= x / z. The present invention relates to a dielectric composition including a composite oxide represented by composition formula Bi_xZn_yNb_zO_1.75 + δ, wherein x, y, and z are satisfied with a relationship of x + y + z = 1.00, 0.20 <= y <= 0.50, 1.5 < x / z <= 3.0, and z < 0.25. The present invention can provide dielectric composition with high reliability at a high temperature.

Description

Dielectric composition and electronic component {DIELECTRIC COMPOSITION AND ELECTRONIC COMPONENT}

The present invention relates to a dielectric composition and an electronic component.

The demand for high performance of mobile communication devices represented by smartphones is high, and for example, in order to enable high-capacity communication at high speed, the number of frequency domains to be used is increasing. The frequency range to be used is a high frequency range such as the GHz band. Among high-frequency components such as baluns, couplers, filters, or duplexers and diplexers in which filters are combined operating in such a high-frequency region, a dielectric material is used as a resonator. Such a dielectric material is required to have low dielectric loss and good frequency selectivity in a high frequency region.

Such mobile communication devices are exposed to temperature changes due to the environment of use, heat generation of parts used in the device, and the like. On the other hand, since the capacitance of the high-frequency component changes with temperature, the high-frequency component is required to have a small temperature dependence of the capacitance, that is, the capacitance temperature coefficient, in a predetermined temperature range.

Therefore, dielectric materials applied to high-frequency components are required to have a small dielectric loss and a capacitance temperature coefficient. Since the reciprocal of the dielectric loss can be expressed as the quality factor Q value, in other words, a dielectric material having a high quality factor Q value in a high frequency region and a small capacity temperature coefficient in a predetermined temperature range is desired.

In addition, in order to cope with analysis of vehicle information and driving information, automatic driving, etc., the development of a connected car having a function of always connecting to the Internet is in progress. The vehicle-mounted communication device mounted on such a connected car is also a type of mobile communication device, and it is required to enable high-capacity communication at high speed. Further, since the vehicle-mounted communication device is sometimes disposed in or near an engine room that becomes high temperature, the vehicle-mounted communication device is particularly required to have high reliability. Therefore, reliability at high temperatures is also required for high-frequency components mounted in vehicle-mounted communication devices.

In addition, with the high performance of mobile communication devices and on-vehicle communication devices, the number of electronic parts mounted in one communication device tends to increase. In order to maintain the size of these communication devices, miniaturization of electronic parts is also required at the same time. In order to miniaturize a high-frequency component using a dielectric material, it is necessary to reduce the electrode area. Therefore, in order to compensate for the decrease in capacitance due to this, it is required that the dielectric material has a high relative dielectric constant in the high-frequency region.

By the way, the capacitance of a high-frequency component using a dielectric material varies depending on the relative dielectric constant of the dielectric material, the electrode area, and the distance between electrodes. In other words, by changing these, the capacitance of the high-frequency component can be adjusted. On the other hand, when the performance of a high-frequency component using a dielectric material is changed according to the purpose of the mounted communication device, etc., by adjusting the relative dielectric constant of the dielectric material without changing the mounting area of the high-frequency component, it is possible to change the performance of the high-frequency component. There are cases where it is required to respond. In this case, rather than changing the composition system of the dielectric material according to the required relative dielectric constant, it is preferable that the dielectric material having the same composition system exhibits the relative dielectric constant according to the performance of the high frequency component.

That is, in order to meet various demands for high frequency components, dielectric properties required for dielectric materials are also diversified.

Conventionally, a Bi-Zn-Nb-O-based oxide is known as a material having a predetermined dielectric property in a high frequency region. For example, in Patent Document 1, a mixture of a Bi ₃ NbO ₇ phase and a Bi ₂ (Zn _2/3 Nb _4/3 )O ₇ phase is disclosed. In addition, Patent Document 2 discloses a sintered body obtained by mixing Bi ₂ O ₃ , ZnO and Nb ₂ O ₅ at a predetermined ratio and firing.

Japanese Patent Publication No. 2009-537444 Japanese Patent Publication No. Hei 4-285046

However, in Patent Document 1, it is described that the absolute value of the temperature coefficient of the dielectric constant of a mixture in which the Bi ₃ NbO ₇ phase and the Bi ₂ (Zn _2/3 Nb _4/3 ) O ₇ phase are mixed at 1:1 is 10 ppm or less. However, since the relative dielectric constant of the mixture is less than 100 and the dielectric quality factor Q at 1 GHz is about 1000, the dielectric properties in the high frequency region are not sufficient from the viewpoint of advancing the miniaturization of high frequency components.

In addition, from the viewpoint of not changing the mounting area of the high-frequency component, since the dielectric constant of the mixture is too large, when the high-frequency component is manufactured in the same shape, even if the capacitance is adjusted by the electrode area or the thickness of the dielectric material, it cannot be completely adjusted. In the same composition system, a low electrostatic capacity cannot be realized.

In addition, Patent Document 2 describes that the absolute value of the temperature coefficient of the dielectric constant of the sintered body obtained by mixing Bi ₂ O ₃ , ZnO and Nb ₂ O ₅ at a predetermined ratio and firing is 100 ppm or less. However, since the no-load Q value at 1 GHz of the sintered body was 400 or less, the dielectric properties in the high frequency region were not sufficient.

The present invention provides a dielectric composition having a high quality factor Q value in a high frequency region, a small absolute value of the capacitance temperature coefficient Tcc in a predetermined temperature range, a relative dielectric constant εr within a predetermined range, and high reliability at a high temperature, and It is a first object to provide an electronic component having the dielectric composition.

In addition, a dielectric composition having a relative dielectric constant εr and a quality factor Q in a high frequency region of a predetermined value or more, a small absolute value of the capacitance temperature coefficient Tcc in a predetermined temperature range, and high reliability at a high temperature, and the dielectric composition It is a second object to provide an electronic component having

In order to achieve the first object, the present invention,

[1] A dielectric composition having a complex oxide containing bismuth, zinc, and niobium,

When the composite oxide is represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ , x, y and z are x+y+z=1.00, x<0.20, 0.20≤y≤0.50, 0.25≤x/z It is a dielectric composition that satisfies the phosphorus relationship.

In order to achieve the second object, the present invention,

[2] A dielectric composition having a complex oxide containing bismuth, zinc, and niobium,

When the composite oxide is represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ , x, y and z are x+y+z=1.00, 0.20≤y≤0.50, 1.5<x/z≤3.0 and z It is a dielectric composition satisfying the relationship of <0.25.

[3] An electronic component including a dielectric layer containing the dielectric composition according to [1] or [2].

According to the present invention, a dielectric composition having a high quality factor Q value in a high frequency region, a small absolute value of the capacitance temperature coefficient Tcc in a predetermined temperature range, a relative dielectric constant εr within a predetermined range, and high reliability at a high temperature, And, an electronic component having the dielectric composition can be provided.

In addition, according to the present invention, a dielectric composition having a relative dielectric constant εr and a quality factor Q value in a high frequency region of a predetermined value or more, a small absolute value of the capacitance temperature coefficient Tcc in a predetermined temperature range, and high reliability at a high temperature, And, an electronic component having the dielectric composition can be provided.

1 is a schematic cross-sectional view of a thin film capacitor as an example of an electronic component according to the present embodiment.

Hereinafter, the present invention will be described in detail in the following order based on specific embodiments.

1. Thin film capacitor

1.1. Overall configuration of thin film capacitor

1.2. Dielectric film

1.2.1. Dielectric composition

1.2.2. First complex oxide

1.2.3. Second complex oxide

1.3. Board

1.4. Lower electrode

1.5. Upper electrode

2. Manufacturing method of thin film capacitor

3. Summary of this embodiment

4. Modification

(1. Thin film capacitor)

First, the electronic component according to the present embodiment is an electronic component (high frequency component) used in a high frequency region. As a high-frequency component, a thin film capacitor in which the dielectric layer is formed of a thin-film dielectric film will be described.

(1.1. Overall configuration of thin film capacitor)

As shown in Fig. 1, in the thin film capacitor 10 as an example of the electronic component according to the present embodiment, a substrate 1, a lower electrode 3, a dielectric film 5, and an upper electrode 4 It has a structure stacked in this order. The lower electrode 3, the dielectric film 5, and the upper electrode 4 form a capacitor portion, and when voltage is applied by connecting the lower electrode 3 and the upper electrode 4 to an external circuit, the capacitor portion is It shows electrostatic capacity and can exert a function as a capacitor. A detailed description of each component will be described later.

In addition, in this embodiment, the underlayer 2 is formed between the substrate 1 and the lower electrode 3 in order to improve the adhesion between the substrate 1 and the lower electrode 3. The material constituting the base layer 2 is not particularly limited as long as it is a material capable of sufficiently securing adhesion between the substrate 1 and the lower electrode 3. For example, when the lower electrode 3 is composed of Cu, the underlying layer 2 is composed of Cr, and when the lower electrode 3 is composed of Pt, the underlying layer 2 is composed of Ti. can do.

Further, in the thin film capacitor 10 shown in Fig. 1, a protective film for blocking the dielectric film 5 from an external atmosphere may be formed.

In addition, the shape of the thin film capacitor is not particularly limited, but it is usually a rectangular parallelepiped shape. In addition, the dimensions are not particularly limited, and the thickness and length may be appropriate dimensions depending on the application.

(1.2. Dielectric film)

The dielectric film 5 is made of the dielectric composition (first dielectric composition and second dielectric composition) according to the present embodiment described later. In addition, in this embodiment, it is preferable that the dielectric film 5 is in the form of a thin film and is a dielectric deposition film formed on a substrate by a known film forming method.

The thin film capacitor having the dielectric film 5 made of the first dielectric composition, even in the high frequency region (for example, 2 GHz), exhibits a high Q value (for example, 1000 or more), and has a good capacity temperature coefficient ( For example, the absolute value of the capacity temperature coefficient may be within 50 ppm/°C) and a good high-temperature acceleration life (eg, an insulation resistance (IR) life at 180°C of 15.0 h or more). In addition, the thin film capacitor can exhibit a relative dielectric constant εr within a predetermined range.

The thin film capacitor having the dielectric film 5 made of the second dielectric composition, even in the high frequency region (e.g., 2 GHz), has a high relative permittivity εr (e.g., 100 or more) and a high Q value (e.g., 1000 or more), and a good capacity temperature coefficient (for example, the absolute value of the capacity temperature coefficient is within 50 ppm/°C) and good high temperature acceleration life (for example, insulation resistance (IR) life at 180°C) 15.0h or more).

The thickness of the dielectric film 5 is preferably 10 nm to 2000 nm, more preferably 50 nm to 1000 nm. If the thickness of the dielectric film 5 is too thin, there is a tendency that dielectric breakdown of the dielectric film 5 is likely to occur. When insulation breakdown occurs, the function as a capacitor cannot be exhibited. On the other hand, if the thickness of the dielectric film 5 is too thick, it is necessary to increase the electrode area in order to increase the capacitance of the capacitor, making it difficult to downsize and reduce the size depending on the design of the electronic component. There are cases.

In general, it is known that the Q value tends to decrease as the thickness of the dielectric decreases. Therefore, in order to obtain a high Q value, it is necessary to constitute a dielectric having a certain thickness, that is, a bulk dielectric. However, even when the dielectric film composed of the dielectric composition according to the present embodiment has a very thin thickness as described above, a high Q value can be obtained.

In addition, the thickness of the dielectric film 5 can be measured by excavating a thin film capacitor including the dielectric film 5 with an FIB (focused ion beam) processing apparatus, and observing the obtained cross section with a scanning electron microscope (SEM). I can.

(1.2.1. Dielectric composition)

The dielectric composition according to the present embodiment contains a complex oxide (Bi-Zn-Nb-O-based oxide) containing bismuth (Bi), zinc (Zn) and niobium (Nb) as a main component. In this embodiment, the main component is a component that occupies 90 mass% or more with respect to 100 mass% of the dielectric composition.

This composite oxide is represented by the general formula A ₂ B ₂ O ₇ and has a pyrochlore phase. In the composite oxide according to the present embodiment, 8 coordination of oxygen to the element occupying the A site (the A site element), and 6 coordination of the oxygen to the element (the B site element) occupying the B site. In addition, the BO ₆ octahedron, in which the B-site element is located at the center of the octahedron composed of oxygen, forms a three-dimensional network in which a vertex of each other is shared, and the A-site element is located in the gap of the network, and the A-site element is oxygen. It is located in the center of a hexahedron consisting of. When the crystallinity of this structure is high, the structure is a pyrochlore type crystal structure.

In this embodiment, the general formula A ₂ B ₂ O ₇ can be represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ . That is, the composite oxide is represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ . In this compositional formula, "x", "y" and "z" are x+y+z=1.00.

Moreover, in the said composite oxide, the amount of oxygen (O) may be a stoichiometric ratio, and may deviate slightly from the stoichiometric ratio. The amount of convenience 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 compositional formula.

Therefore, "x" represents the content ratio of Bi in the metal element in the composition formula of the composite oxide, and "y" represents the content ratio of Zn in the metal element in the composition formula of the composite oxide, "Z" represents the content ratio of Nb in the metal element in the composition formula of the composite oxide.

In the above general formula, Bi occupies A site and Nb occupies B site. On the other hand, Zn can occupy either of A site and B site in the said general formula. Therefore, in the complex oxide, in addition to the hexahedron for 8 times oxygen to Bi and the octahedron for 6 times oxygen to Nb, there exist a hexahedron for 8 times oxygen to Zn and an octahedron for 6 times oxygen to Zn.

In this embodiment, the composite oxide having the above structural characteristics is divided into a first composite oxide and a second composite oxide.

(1.2.2. First Composite Oxide)

In the first composite oxide containing Bi, Zn, and Nb, the ratio of the polyhedron in which oxygen is coordinated with Zn affects the stability of the structure. In this embodiment, "y" indicating the content ratio of Zn is 0.20 or more and 0.50 or less. Moreover, it is preferable that "y" is 0.30 or more.

By making ``y'' within the above range, the ratio of the hexahedron for Zn to 8 times oxygen and the octahedron for Zn to 6 times increased, and the imbalance of the polyhedral structure in the crystal structure is suppressed. As a result, it becomes difficult to cause structural change due to temperature change. As a result, even when the temperature changes, the capacitance tends to be kept constant, so that the absolute value (|Tcc|) of the capacitance temperature coefficient Tcc can be made within a predetermined range.

If ``y'' is too small, in the first complex oxide, the ratio occupied by the hexahedron with 8 times the amount of oxygen in Bi and the octahedron with 6 times the amount of oxygen in Nb increases, increasing the imbalance of the polyhedral structure, which is liable to change the structure. Since there is a tendency, the capacity temperature coefficient Tcc tends to deteriorate. On the other hand, when "y" is too large, it tends to deviate from the range of the appropriate relative permittivity εr specified in the present embodiment.

In the first composite oxide, the content ratio of Bi ("x") is less than 0.20. Moreover, "x/z" which shows the content ratio ("x") of Bi with respect to the content ratio ("z") of Nb is 0.25 or more. By making "x" and "x/z" within the above ranges, structure disturbance (disorder) occurs within an appropriate range at the B site, so that a good quality factor Q value is obtained.

Moreover, by making "x" within the said range, the ratio occupied by Nb in the 1st composite oxide becomes higher than the ratio occupied by Bi. The difference between the electronegativity of oxygen and Nb is greater than the difference between the electronegativity of oxygen and Bi. Therefore, in the first composite oxide, since the ionic bond between the metal element and oxygen is strong, oxygen defects are less likely to occur, and the accelerated life at high temperature is improved.

In the first composite oxide, by making "x", "y" and "z" within the above ranges, the quality factor Q value, the capacity temperature coefficient Tcc, and the high temperature acceleration life can be improved. Further, it becomes easy to make the relative dielectric constant εr within a predetermined range.

(1.2.3. The second complex oxide)

In the second composite oxide containing Bi, Zn, and Nb, the ratio of the polyhedron in which oxygen is coordinated with Zn affects the stability of the structure. In this embodiment, "y" indicating the content ratio of Zn is 0.20 or more and 0.50 or less. Moreover, it is preferable that "y" is 0.30 or more.

If ``y'' is too small, in the second complex oxide, the ratio occupied by the hexahedron with 8 times the amount of oxygen in Bi and the octahedron with 6 times the amount of oxygen in Nb increases, increasing the imbalance of the polyhedral structure, which is liable to change the structure. Since there is a tendency, the capacity temperature coefficient Tcc tends to deteriorate. On the other hand, if "y" is too large, the ratio of the polyhedron to which oxygen is coordinated with Zn becomes too large, and the component contributing to the relative dielectric constant in the second composite oxide decreases, so that the relative dielectric constant εr tends to deteriorate.

In the second composite oxide, "x/z" indicating the content ratio of Bi ("x") to the content ratio of Nb ("z") is greater than 1.50 and not more than 3.00. By making ``x'' and ``x/z'' within the above ranges, disorganization of the atomic arrangement (disorder) occurs within an appropriate range at the A site of the second composite oxide, while maintaining a good quality factor Q value. , Due to this dispatch, the relative dielectric constant εr can be improved.

In addition, in the second composite oxide, the content ratio ("z") of Nb is less than 0.25. If "z" is too large, the quality factor Q value tends to deteriorate. It is preferable that "z" is 0.15 or more.

Further, by setting "z" within the above range, the ratio of Bi in the second composite oxide becomes higher than the ratio of Nb, and the ratio of the hexahedron in which oxygen is eight times larger than that of Bi increases. As a result, oxygen defects are less likely to occur, and the accelerated life at high temperatures is improved.

In the second composite oxide, by making "x", "y" and "z" within the above ranges, the relative dielectric constant εr, the quality factor Q value, the capacity temperature coefficient Tcc, and the high temperature acceleration life can be improved. .

In addition, the first dielectric composition described above has a first composite oxide as a main component, and the second dielectric composition described above has a second composite oxide as a main component. In addition, the dielectric composition (the first dielectric composition and the second dielectric composition) according to the present embodiment may contain trace amounts of impurities, subcomponents, and the like within the range in which the effects of the present invention are exhibited. As such a component, Mn, Ca, and Ba are illustrated, for example.

(1.3. Substrate)

The substrate 1 shown in Fig. 1 is made of a material having a mechanical strength sufficient to support the underlying layer 2, the lower electrode 3, the dielectric film 5, and the upper electrode 4 formed thereon. If configured, it will not be particularly limited. For example, Si single crystal, SiGe single crystal, GaAs single crystal, InP single crystal, SrTiO ₃ single crystal, MgO single crystal, LaAlO ₃ single crystal, ZrO ₂ single crystal, MgAl ₂ O ₄ single crystal, NdGaO ₃ single crystal substrate consisting of a single crystal and so on; Al ₂ O Ceramic polycrystalline substrates composed of ₃ polycrystals, ZnO polycrystals, SiO ₂ polycrystals, etc.; Metal substrates composed of metals such as Ni, Cu, Ti, W, Mo, Al, Pt, alloys thereof, and the like are exemplified. In this embodiment, a Si single crystal is used as a substrate from the viewpoint of low cost and workability.

The thickness of the substrate 1 is set to 10 μm to 5000 μm, for example. If the thickness is too small, the mechanical strength may not be secured in some cases, and if the thickness is too large, there may be a problem that it cannot contribute to miniaturization of the electronic component.

The substrate 1 has a different resistivity depending on the material of the substrate. When a substrate is formed of a material having a low resistivity, current leaks to the substrate side during operation of the thin film capacitor may affect the electrical characteristics of the thin film capacitor. Therefore, when the resistivity of the substrate 1 is low, it is preferable to perform an insulating treatment on the surface thereof so that the current during operation of the capacitor does not flow through the substrate 1.

For example, in the case of using a Si single crystal as the substrate 1, it is preferable that an insulating layer is formed on the surface of the substrate 1. The material constituting the insulating layer and its thickness are not particularly limited as long as sufficient insulation between the substrate 1 and the capacitor portion is ensured. In this embodiment, SiO ₂ , Al ₂ O ₃ , Si ₃ N _x and the like are exemplified as materials constituting the insulating layer. Moreover, it is preferable that the thickness of an insulating layer is 0.01 micrometers or more.

(1.4. Lower electrode)

As shown in FIG. 1, on the substrate 1, the lower electrode 3 is formed in the form of a thin film with the underlying layer 2 interposed therebetween. The lower electrode 3 is an electrode for functioning as a capacitor by interposing the dielectric film 5 together with the upper electrode 4 to be described later. The material constituting the lower electrode 3 is not particularly limited as long as it is a material having conductivity. For example, metals such as Pt, Ru, Rh, Pd, Ir, Au, Ag, and Cu, alloys thereof, or conductive oxides are exemplified.

The thickness of the lower electrode 3 is not particularly limited as long as it is thick enough to function as an electrode. In this embodiment, it is preferable that the thickness is 0.01 μm or more.

(1.5. Upper electrode)

As shown in Fig. 1, on the surface of the dielectric film 5, the upper electrode 4 is formed in a thin film shape. The upper electrode 4 is an electrode for functioning as a capacitor with the dielectric film 5 interposed therebetween together with the lower electrode 3 described above. Therefore, the upper electrode 4 has a polarity different from that of the lower electrode 3.

As with the lower electrode 3, the material constituting the upper electrode 4 is not particularly limited as long as it is a material having conductivity. For example, metals such as Pt, Ru, Rh, Pd, Ir, Au, Ag, and Cu, alloys thereof, or conductive oxides are exemplified.

(2. Manufacturing method of thin film capacitor)

Next, an example of a method of manufacturing the thin film capacitor 10 shown in FIG. 1 will be described below.

First, the substrate 1 is prepared. When, for example, a Si single crystal substrate is used as the substrate 1, an insulating layer is formed on one main surface of the substrate. As a method of forming the insulating layer, a known film forming method such as a thermal oxidation method and a CVD (Chemical Vapor Deposition) method may be used.

Subsequently, on the formed insulating layer, a thin film of a material constituting the underlying layer is formed using a known film forming method to form the underlying layer 2.

After the underlying layer 2 is formed, a thin film of a material constituting the lower electrode is formed on the underlying layer 2 by using a known film forming method to form the lower electrode 3.

Subsequently, a dielectric film 5 is formed on the lower electrode 3. In this embodiment, a dielectric film 5 as a deposition film is formed by depositing a material constituting the dielectric film 5 on the lower electrode 3 in a thin film form by a known film formation method.

Known film formation methods include, for example, vacuum evaporation, sputtering, PLD (pulse laser deposition), MO-CVD (organic metal chemical vapor deposition), MOD (organic metal decomposition), sol gel method, and CSD (chemical solution deposition). Law), etc. are illustrated. In addition, raw materials (evaporation materials, various target materials, organometallic materials, etc.) used at the time of film formation sometimes contain trace amounts of impurities, subcomponents, and the like, but there is no particular problem as long as desired dielectric properties are obtained.

For example, in the case of using the PLD method, a dielectric film 5 is formed on the lower electrode 3 using a target having a desired composition. In this embodiment, it is preferable to perform film formation conditions as follows. It is preferable that the oxygen pressure is 0.1 to 10 Pa. Moreover, it is preferable to perform film formation at room temperature. The laser power is preferably 3 to 5 J/cm ² , and the pulse frequency is preferably 1 to 20 Hz.

In this embodiment, after forming the dielectric film, the dielectric film is subjected to a rapid thermal annealing treatment (Rapid Thermal Anneal: RTA). In this embodiment, as a condition for performing RTA, the atmosphere is preferably an oxygen atmosphere, the heating rate is preferably 1000° C./min or more, the annealing time is preferably 1 to 30 minutes, and the annealing temperature It is preferable to set it to 300 degreeC or more and 750 degreeC or less.

Next, on the formed dielectric film 5, a thin film of a material constituting the upper electrode is formed by a known film forming method to form the upper electrode 4.

Through the above steps, as shown in Fig. 1, a thin film capacitor 10 in which a capacitor portion (lower electrode 3, dielectric film 5, and upper electrode 4) is formed on a substrate 1 is obtained. . Further, the protective film for protecting the dielectric film 5 may be formed by a known film forming method so as to cover at least a portion of the dielectric film 5 exposed to the outside.

(3. Summary of this embodiment)

In this embodiment, attention is paid to the Bi-Zn-Nb-O-based oxide. The Bi-Zn-Nb-O-based oxide is a composite oxide represented by the general formula A ₂ B ₂ O ₇ . In this composite oxide, Zn can occupy both the A site and the B site, and forms two types of polyhedra. The inventors of the present invention have found that by increasing the ratio of these two types of polyhedron, the structure of the Bi-Zn-Nb-O-based oxide is stabilized, and structural change due to temperature change is less likely to occur. Therefore, in this embodiment, the capacity temperature coefficient Tcc is improved by making the content ratio of Zn in the Bi-Zn-Nb-O-based oxide within the above range.

In addition, the present inventors reduce defects in Bi-Zn-Nb-O-based oxides by controlling the content ratio of Bi to the content ratio of Bi occupying the A site and Nb occupying the B site. , It was also found that the Q value of the quality factor and the high temperature acceleration life improved. Thus, in this embodiment, by making the ratio within the above range, a high quality factor Q value and a good high temperature acceleration life are obtained.

Specifically, the first dielectric composition described above exhibits a high quality factor Q value of 1000 or more even in a high frequency range of 2 GHz or more, and the absolute value of the capacitance temperature coefficient Tcc is 50 ppm/° C. or less, and the insulation resistance (IR) at 180° C. ) Life can be over 15.0h.

In addition, the present inventors control the content ratio of Nb occupying the B site and the content ratio of Bi occupying the A site relative to the content ratio of Nb, thereby improving the quality factor Q value, the relative dielectric constant εr and the high temperature acceleration life. I also found it. Therefore, in this embodiment, by making the ratio within the above range, a high relative dielectric constant εr, a high quality factor Q value, and a good high temperature acceleration life are obtained.

Specifically, the second dielectric composition described above exhibits a high relative dielectric constant εr of 100 or more and a high quality factor Q value of 1000 or more even in a high frequency range of 2 GHz or more, and the absolute value of the capacity temperature coefficient Tcc is 50 ppm/° C. or less, 180 The insulation resistance (IR) life in °C can be 15.0 h or more.

(4. Modification)

In the above-described embodiment, the case where the dielectric film is composed of only the dielectric composition according to the present embodiment has been described, but an electron having a laminated structure in which a dielectric film composed of the dielectric composition according to the present embodiment and a film composed of another dielectric composition are combined. It may be a part. For example, _by forming a stacked structure with an amorphous dielectric film or crystal film such as Si ₃ N _x , SiO _x , Al ₂ O _x , ZrO _x , Ta ₂ O _x, etc., the impedance and analogy of the dielectric film 5 It becomes possible to adjust the temperature change of the thrill.

Further, a multilayer capacitor having a plurality of dielectric films composed of the dielectric composition according to the present embodiment may be used.

In the above-described embodiment, in order to improve the adhesion between the substrate and the lower electrode, the base layer is formed. However, when the adhesion between the substrate and the lower electrode can be sufficiently secured, the base layer can be omitted. In addition, in the case of using metals such as Cu and Pt that can be used as electrodes, their alloys, oxide conductive materials, etc. as the material constituting the substrate, the underlying layer and the lower electrode can be omitted.

In addition, in the above-described embodiment, the dielectric layer is a dielectric deposition film formed by a known film forming method, but the dielectric layer may be composed of a sintered body obtained by firing a molded body obtained by molding the raw material powder of the dielectric composition.

As an electronic component having a dielectric layer composed of such a sintered body, a single-layer capacitor in which the dielectric layer is a single layer may be used, or a multilayer capacitor in which a plurality of dielectric layers are stacked may be used.

The single-layer capacitor has a configuration in which an electrode is formed on an opposite surface of the dielectric composition. In addition, the multilayer capacitor has a multilayer body in which a plurality of dielectric layers made of a dielectric composition and internal electrode layers are alternately laminated. At both ends of this laminate, a pair of terminal electrodes which are respectively connected to the internal electrode layer are formed.

As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments at all, and various aspects may be modified within the scope of the present invention.

[Example]

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

(Experimental Example 1)

First, a target required for formation of a dielectric film was produced as follows.

As a raw material powder for target production, powders of Bi ₂ O ₃ , ZnO and Nb ₂ O ₅ were prepared. These powders were weighed to obtain the final composition of the samples of Examples 1 to 9 and Comparative Examples 1 to 6 shown in Table 1. The weighed raw material powder, water, and ZrO ₂ beads having a diameter of ₂ mm were placed in a photosphere pot made of polypropylene having a volume of 1 L, and wet mixing was performed for 20 hours. Thereafter, the mixed powder slurry was dried at 100°C for 20 hours, the obtained mixed powder was placed in an Al ₂ O ₃ crucible, and calcined under the sintering conditions of holding at 800°C for 5 hours in the air, thereby forming the calcined powder. Got it.

The obtained calcined powder was put in a mortar, and an aqueous solution of PVA (polyvinyl alcohol) having a concentration of 6 wt% as a binder was added so as to be 4 wt% with respect to the calcined powder, and granulated powder was prepared using a mortar. The produced granulated powder was put into a mold having a diameter of 20 mm so that the thickness was about 5 mm, and pressure molding was performed using a uniaxial pressure press to obtain a molded body. As for the molding conditions, the pressure was 2.0×10 ⁸ Pa and the temperature was room temperature.

Thereafter, about the obtained molded body, the temperature increase rate was set at 100°C/hour, the holding temperature was set at 400°C, and the temperature holding time was set at 4 hours, and the binder removal treatment was performed in the atmosphere at normal pressure. Subsequently, the temperature increase rate was set to 200°C/hour, the holding temperature was set to 1000°C to 1200°C, and the temperature holding time was set to 12 hours, and firing was performed in the atmosphere at normal pressure to obtain a sintered body.

Both sides were polished with a cylindrical polishing machine so that the thickness of the obtained sintered body was 4 mm, and a target for forming a dielectric film was obtained.

Subsequently, a substrate having a width of 10 mm × 10 mm was prepared having SiO ₂ as an insulating layer having a thickness of 0.5 μm on the surface of a Si single crystal substrate having a thickness of 350 μm. On the surface of this substrate, a Ti thin film as an underlying layer was formed by sputtering to a thickness of 20 nm.

Then, a Pt thin film as a lower electrode was formed on the Ti thin film formed above by sputtering to a thickness of 4 μm.

A dielectric film was formed on the Ti/Pt thin film. In this embodiment, a dielectric film was formed on the lower electrode by the PLD method so as to have a thickness of 400 nm using the target fabricated above. As for the film formation conditions by the PLD method, the oxygen pressure was 1 Pa, the laser power was 3 J/cm ² , the laser pulse frequency was 10 Hz, and the film formation temperature was room temperature. Further, in order to expose a part of the lower electrode, a metal mask was used to form a region in which a dielectric film was not formed. After the dielectric film was formed, the dielectric film was subjected to a rapid thermal annealing treatment (Rapid Thermal Anneal: RTA) in which the temperature increase rate was set at 1000°C/min in an oxygen atmosphere and maintained at 550°C for 1 minute.

Then, on the obtained dielectric film, an Ag thin film as an upper electrode was formed using a vapor deposition apparatus. By forming the shape of the upper electrode to have a diameter of 100 μm and a thickness of 100 nm using a metal mask, samples of thin film capacitors having the configuration shown in FIG. 1 (Examples 1 to 9 and Comparative Examples 1 to 6) were obtained.

In addition, the composition of the dielectric film was analyzed at room temperature using a WD-XRF (wavelength dispersion type fluorescence X-ray element analysis) device (ZSX-100e manufactured by Rigaku Corporation) for all samples, and the composition shown in Table 1. And confirmed that it is consistent with. In addition, the thickness of the dielectric film was set as a value obtained by excavating a thin film capacitor with FIB, observing the obtained cross section with a scanning electron microscope (SEM), and measuring it.

For all the obtained thin film capacitor samples, the relative dielectric constant εr, Q value, the temperature coefficient Tcc of the electrostatic capacitance, and the high-temperature acceleration lifetime were measured by the method shown below.

(Q value and relative permittivity)

Q value and relative dielectric constant are measured under the conditions of a frequency of 2 GHz and an input signal level (measurement voltage) of 0.5 Vrms with an RF impedance/material analyzer (4991A manufactured by Agilent) at a reference temperature of 25° C. for a thin film capacitor sample With the increased capacitance. It was calculated from the thickness of the dielectric film obtained above. In this example, the higher the Q value is, and the sample having a Q value of 1000 or more was judged to be good. In addition, in this example, a sample having a relative dielectric constant of 50 or more and less than 80 was judged to be good. Moreover, the results are shown in Table 1.

(Temperature coefficient of electrostatic capacity (Tcc))

The temperature coefficient of the capacitance is measured by measuring the capacitance at the measurement temperature in the same manner as above, except that the measurement temperature is changed every 25°C from -55°C to 125°C using a thermostat. It was calculated as the rate of change with respect to the electrostatic capacity at 25°C (unit ppm/°C). Moreover, it is preferable that the temperature coefficient of the electrostatic capacity is small, and a sample having an absolute value (|Tcc|) of the electrostatic capacity temperature coefficient within 50 ppm/°C was judged to be good. Table 1 shows the results.

(High temperature acceleration life)

The insulation resistance life was measured as the high temperature accelerated life. At 180° C., a DC voltage of 16 V/µm was applied to the dielectric film obtained above, and a change in insulation resistance with time before application of the DC voltage was measured. The time until the insulation resistance of the dielectric film became 10 ⁵ Ω or less was used as the lifetime, and the lifetime was measured for 20 samples, and the average value was taken as the insulation resistance (IR) lifetime. It is preferable that the IR lifetime is long, and a sample having an IR lifetime of 15.0 h or more was judged to be good. Table 1 shows the results.

From Table 1, in the composite oxide containing Bi, Zn, and Nb, samples in which the relationship between ``x'', ``y'' and ``z'' is within the above-described range have a high quality factor Q in the high frequency region (2 GHz). It was confirmed that it had a value (1000 or more), good temperature characteristics (|Tcc|≤50ppm/°C), and a good IR lifetime (15.0h or more), and that the relative dielectric constant εr was within a predetermined range.

(Experimental Example 2)

In the composite oxide containing Bi, Zn, and Nb, a dielectric film was formed in the same manner as in Experimental Example 1, except that the values of "x", "y", and "z" were set to the values shown in Table 2. Samples of thin film capacitors (Examples 11 to 19 and Comparative Examples 11 to 16) were obtained. The sample of the obtained thin film capacitor was evaluated in the same manner as in Experimental Example 1. The results are shown in Table 2. In addition, in the evaluation of the relative dielectric constant, a sample having a relative dielectric constant of 100 or more was judged to be good.

From Table 2, in the composite oxide containing Bi, Zn, and Nb, the sample in which the relationship between "x", "y" and "z" is within the above-described range has a high relative dielectric constant εr in the high frequency region (2 GHz). (100 or more), a high quality factor Q value (1000 or more), good temperature characteristics (|Tcc|≦50 ppm/°C), and it was confirmed that it had a good IR lifetime (15.0 h or more).

Advantageous Effects of Invention According to the present invention, a dielectric composition having a high Q value in a high frequency region, a small capacity temperature coefficient in a predetermined temperature range, and a good high temperature acceleration life can be obtained. Such a dielectric composition is suitable as a thin-film dielectric film, and is suitable for high-frequency electronic components, such as a balun, a coupler, a filter, or a duplexer or diplexer in which filters are combined.

10: thin film capacitor 1: substrate
2: base layer 3: lower electrode
4: upper electrode 5: dielectric film

Claims (3)

As a dielectric composition having a complex oxide containing bismuth, zinc and niobium,
When the composite oxide is represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ , x, y and z are x+y+z=1.00, x<0.20, 0.20≤y≤0.50, 0.25≤x A dielectric composition satisfying the relationship of /z. As a dielectric composition having a complex oxide containing bismuth, zinc and niobium,
When the composite oxide is represented by the composition formula Bi _x Zn _y Nb _z O _1.75+δ , x, y and z are x+y+z=1.00, 0.20≤y≤0.50, 1.5<x/z≤3.0 And a relationship of z &lt; 0.25. An electronic component comprising a dielectric layer comprising the dielectric composition according to claim 1 or 2.

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