JP2020161796A - Dielectric thin film, electronic component, thin film capacitor, and electronic circuit board - Google Patents

Abstract

To provide a dielectric thin film having excellent temperature characteristics.SOLUTION: A dielectric thin film includes an oxide having a perovskite structure. The oxide contains Bi, and an element E1, an element E2, and Ti. The element E1 is at least one element selected from the group consisting of Na and K. The element E2 is at least one element selected from the group consisting of Ca, Sr, and Ba. The oxide contains a twin crystal.SELECTED DRAWING: Figure 2

Description

The present invention relates to dielectric thin films, electronic components, thin film capacitors and electronic circuit boards.

With the recent miniaturization of electronic devices, the space for accommodating electronic components in the electronic devices becomes narrower. Therefore, small and thin electronic components are required. A thin film capacitor is a kind of electronic component mounted on various electronic devices. (See Patent Documents 1 to 3 below.) In Japan, thin film capacitors are often called thin film capacitors. The substrate, insulating film, electrodes, and dielectric thin film provided in the thin film capacitor are thinner than the members constituting the conventional laminated ceramic capacitor, and the thickness of the entire thin film capacitor is also thinner than that of the conventional laminated ceramic capacitor. Therefore, it is expected that thin film capacitors will be mounted on small electronic devices in place of conventional multilayer ceramic capacitors. In recent years, thin film capacitors embedded in electronic circuit boards have also been developed.

Japanese Unexamined Patent Publication No. 2000-49045 International Publication 2017/012800 Pamphlet Japanese Unexamined Patent Publication No. 2006-160594

Electronic devices equipped with thin film capacitors are used in various environments. However, the relative permittivity of a conventional dielectric thin film tends to change with a change in temperature. Therefore, in order for an electronic device to operate stably under various environments, it is required that the change in the relative permittivity due to a change in temperature is small. The temperature characteristics described below are properties in which the relative permittivity does not easily change with changes in temperature.

For example, Patent Document 3 discloses that the dielectric ceramic contains at least one selected from the group consisting of Si, Mg, Mn, Y and Ca in order to improve the temperature characteristics. The laminated ceramic capacitor provided with this dielectric ceramic achieves X5R based on the EIA standard. X5R means the performance in which the rate of change of the capacitance of the capacitor is -15% or more and 15% or less in the temperature range of −55 ° C. or higher and 85 ° C. or lower.

In contrast to the above-mentioned dielectric ceramics, conventional dielectric thin films do not always have excellent temperature characteristics.

An object of the present invention is to provide a dielectric thin film having excellent temperature characteristics, an electronic component provided with the dielectric thin film, a thin film capacitor, and an electronic circuit substrate.

The dielectric thin film according to one aspect of the present invention contains an oxide having a perovskite structure, the oxide contains Bi, an element E1, an element E2, and Ti, and the element E1 is selected from the group consisting of Na and K. The element E2 is at least one element selected from the group consisting of Ca, Sr, and Ba, and the oxide contains a perovskite.

The Bi content in the dielectric thin film may be expressed as [Bi] mol%, and the total content of the element E2 in the dielectric thin film may be expressed as [E2] mol%, [Bi] / [ E2] may be 0.214 or more and 4.500 or less.

The electronic component according to one aspect of the present invention includes the above-mentioned dielectric thin film.

The thin film capacitor according to one aspect of the present invention includes the above-mentioned dielectric thin film.
The electronic circuit board according to one aspect of the present invention may include the above-mentioned dielectric thin film.
The electronic circuit board according to one aspect of the present invention may include the above electronic components.
The electronic circuit board according to one aspect of the present invention may include the above-mentioned thin film capacitor.

According to the present invention, a dielectric thin film having excellent temperature characteristics, an electronic component including the dielectric thin film, a thin film capacitor, and an electronic circuit substrate are provided.

FIG. 1 is a schematic cross-sectional view of an electronic component (thin film capacitor) according to an embodiment of the present invention. FIG. 2 is a schematic perspective view of a unit cell of a perovskite structure. FIG. 3 is a schematic cross-sectional view of the twin crystals of the oxide. FIG. 4 is a schematic diagram of a fast Fourier transform pattern of an image of twin crystals of an oxide taken by a transmission electron microscope. FIG. 5 is a crystal lattice image of the dielectric thin film of Example 1 taken by a transmission electron microscope. FIG. 6A is an FFT pattern of the image shown in FIG. 5, and FIG. 6B is an enlarged view of 211 spots shown in FIG. 6A. FIG. 7A is a schematic cross-sectional view of an electronic circuit board according to an embodiment of the present invention, and FIG. 7B is a portion 90A shown in FIG. 7A. It is an enlarged view of.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, equivalent components are labeled with equivalent reference numerals. The present invention is not limited to the following embodiments.

A thin film capacitor will be described as an example of the electronic component according to the present embodiment. However, electronic components are not limited to thin film capacitors.

(Structure of thin film capacitor)
FIG. 1 is a cross section of a thin film capacitor 100 perpendicular to the surface of the dielectric thin film 40. In other words, FIG. 1 is a cross section of the thin film capacitor 100 parallel to the thickness direction of the dielectric thin film 40. As shown in FIG. 1, the thin film capacitor 100 according to the present embodiment includes a substrate 10, an adhesive film 20 overlapping the substrate 10, a lower electrode 30 overlapping the adhesive film 20, and a dielectric thin film 40 overlapping the lower electrode 30. An upper electrode 50 that overlaps the dielectric thin film 40, and a protective film 70 that covers the lower electrode 30, the dielectric thin film 40, and the upper electrode 50 are provided.

The capacitor portion 60 is composed of a lower electrode 30, a dielectric thin film 40, and an upper electrode 50. The lower electrode 30 and the upper electrode 50 are connected to an external circuit. By applying a voltage to the dielectric thin film 40 located between the lower electrode 30 and the upper electrode 50, dielectric polarization of the dielectric thin film 40 occurs, and electric charges are stored in the capacitor portion 60.

The shape of the thin film capacitor 100 may be, for example, a rectangular parallelepiped. However, the shape and dimensions of the entire thin film capacitor are not limited.

(Dielectric thin film)
The dielectric thin film 40 according to the present embodiment contains an oxide having a perovskite structure. Oxides include Bi (bismuth), element E1, element E2, and Ti (titanium). The element E1 is at least one alkali metal element selected from the group consisting of Na (sodium) and K (potassium). The element E2 is at least one alkaline earth metal element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium).

The unit cell of the perovskite structure is shown in FIG. The unit cell uc of the perovskite structure may consist of an element located at the A site, an element located at the B site, and oxygen (O). The element located at the A site may be at least one selected from the group consisting of Bi, element E1 and element E2. The element located at the B site may be Ti. Reference numerals a1, b1 and c1 in FIG. 2 are basic vectors constituting a cubic crystal or a tetragonal crystal having a perovskite structure.

The dielectric thin film 40 according to the present embodiment is superior to the conventional dielectric thin film in DC bias characteristics. The DC bias characteristic is a property in which the relative permittivity is unlikely to decrease as the strength of the DC electric field applied to the dielectric thin film 40 increases. The following description of the DC bias properties of the dielectric thin film 40 includes hypotheses or theoretical inferences. The reason why the DC bias characteristic of the dielectric thin film 40 is improved is not necessarily limited to the following mechanism.

The dielectric property of an oxide having a perovskite structure is due to the displacement of the ions of each element constituting the oxide under voltage. As the voltage increases, the displacement amount of each ion saturates, so that the relative permittivity of the oxide tends to decrease. Even if the voltage strength is the same, the vibration of each ion constituting the oxide becomes smaller by applying the DC voltage. However, in the case of this embodiment, Bi, the element E1 and the element E2 constituting the oxide are different from each other in the atomic radius or the ionic radius. Therefore, due to the arrangement of Bi, element E1 and element E2 at the A site, there is a margin of space in the perovskite structure. As a result, Ti becomes easy to move in the perovskite structure, the dielectric thin film 40 is easily polarized, and the DC bias characteristic of the dielectric thin film 40 is improved. In other words, the combination of Bi, element E1 and element E2 increases the strength of the DC electric field that saturates the displacement of ions such as Ti. As will be described later, when [Bi] / [E2] is 0.214 or more and 4.500 or less, the DC bias characteristic is likely to be improved by the above mechanism.

When the oxide having a perovskite structure contains Bi, the elements E1 and Ti, and does not contain the element E2, the Curie point of the oxide is about 300 ° C. However, since the oxide contains the element E2 in addition to Bi, the element E1 and Ti, the Curie point of the oxide approaches room temperature. As a result, the absolute value of the relative permittivity of the oxide increases, and the relative permittivity of the oxide under a DC electric field also increases.

In order to reduce the size of the electronic device on which the thin film capacitor 100 is mounted, it is desired to make the dielectric thin film 40 thinner. Further, in order to increase the capacitance of the thin film capacitor 100, it is desired to make the dielectric thin film 40 thinner. However, even if the DC voltage applied to the dielectric thin film 40 is constant, the strength of the DC electric field extending to the dielectric thin film 40 increases as the thickness of the dielectric thin film 40 decreases. The relative permittivity of the dielectric thin film 40 tends to decrease as the strength of the DC electric field increases. However, the dielectric thin film 40 according to the present embodiment is superior in DC bias characteristics to the conventional dielectric thin film. As a result, even when the thickness of the dielectric thin film 40 is thinner than that of the conventional dielectric thin film, the decrease in the relative permittivity of the dielectric thin film 40 is suppressed.

The oxide contains twins. A twin is a state of a crystal composed of two or more single crystals of the same type bonded to each other at a constant angle. Each single crystal constituting the twin of the oxide has the above-mentioned perovskite structure, and each single crystal constituting the twin of the oxide contains Bi, element E1, element E2, Ti and O. An example of twins of oxide is shown in FIG. For example, the twin crystal tw of the oxide may consist of the first crystal c1 and the second crystal c2. The first crystal c1 and the second crystal c2 have plane symmetry with respect to the plane p. FIG. 3 is a cross section of the twin crystal tw in the direction perpendicular to the first crystal plane cp1 and the second crystal plane cp2. Therefore, in FIG. 3, the first crystal plane cp1 and the second crystal plane cp2 are represented by line segments. The first crystal plane cp1 belonging to the first crystal c1 is oriented in the first orientation d1. That is, the first orientation d1 is the normal direction of the first crystal plane cp1. The second crystal plane cp2 belonging to the second crystal c2 is oriented in the second orientation d2. That is, the second orientation d2 is the normal direction of the second crystal plane cp2. The first crystal plane cp1 and the second crystal plane cp2 are equivalent crystal planes in the perovskite structure, but the first orientation d1 and the second orientation d2 are not parallel. The structure of twins is not limited to the structure shown in FIG.

If the dielectric thin film 40 does not contain twins of oxide, a phase transition of oxide is likely to occur with a change in temperature. The relative permittivity of the dielectric thin film 40 is likely to change due to the phase transition. On the other hand, since the twin crystal tw of the oxide is composed of two or more single crystals of the same type bonded to each other at a constant angle, distortion in the crystal structure is formed in the oxide. Since the strain on the crystal structure suppresses the progress of the phase transition of the oxide, the change in the relative permittivity of the dielectric thin film 40 is suppressed. That is, the dielectric thin film 40 can have excellent temperature characteristics because the dielectric thin film 40 contains twin crystals of oxide. However, the reason for improving the temperature characteristics is not necessarily limited to the above mechanism.

Whether or not the dielectric thin film 40 contains twins of oxide can be confirmed by the following method.

A thin piece (sample) is formed by processing the dielectric thin film 40 with a focused ion beam (FIB). A crystal lattice image in the crystal grains in the flakes is photographed by a transmission electron microscope (TEM). The field of view of the TEM may be, for example, 35 nm in length × 35 nm in width. An FFT pattern is obtained by a fast Fourier transform (FFT) of a crystal lattice image in a crystal grain imaged by a TEM. An example of the FFT pattern is shown in FIG. Each of 100, 200, 011, 111, and 211 in FIG. 4 is an index related to the crystal orientation in the above-mentioned perovskite structure. 000 corresponds to the origin for defining the position of each spot in the FFT pattern. If the crystal grains do not contain oxide twins, the FFT pattern has multiple spots, and one spot corresponds to one crystal orientation. On the other hand, when the crystal grains contain twins of oxide, two or more spots corresponding to one crystal orientation appear. That is, when the crystal grains contain twins of oxide, the spots corresponding to one crystal orientation are separated into at least two spots. The FFT pattern differs depending on the field of view observed by the TEM, but the FFT pattern may be a pattern other than FIG. 4 as long as the spots in the FFT pattern can be confirmed.

When 20 fields of view in the flakes (sample) are observed based on the FFT pattern, it is preferable that twins are contained in at least 2 of the 20 fields. The dimensions of each field of view are as described above. The dielectric thin film 40 may have a plurality of crystal grains containing oxides. At least some of the plurality of crystal grains may contain oxide twins. All of the plurality of crystal grains may contain twins of oxide. When the particle size of the crystal grain is 150 nm or more, it is preferable that at least two places in the same crystal grain are observed.

The Bi content in the dielectric thin film 40 may be expressed as [Bi] mol%. The unit of [Bi] may be atomic%. The total content of the element E2 in the dielectric thin film 40 may be expressed as [E2] mol%. The unit of [E2] may be atomic%. [Bi] / [E2] may be 0.214 or more and 4.500 or less. Since [Bi] / [E2] are within the above range, the temperature characteristics and DC bias characteristics of the dielectric thin film 40 are likely to be improved.

The composition of the oxide contained in the dielectric thin film 40 may be represented by the following chemical formula 1a or chemical formula 1b. X, α, β, s, t and u described in Chemical Formula 1a and Chemical Formula 1b are real numbers. The unit of x, α, β, s, t and u is mоl. Both chemical formula 1a and chemical formula 1b satisfy all of the following inequalities 2-9.
<Chemical formula 1a>
_{(1-x) Bi 1-} α-β Na α K β TiO 3 -xCa s Sr t Ba u TiO 3
<Chemical formula 1b>
_{(Bi 1-α-β Na} α K β) 1-x (Ca s Sr t Ba u) x TiO 3
0 <x <1 (2)
0.4 <α + β <0.6 (3)
0 ≤ α <0.6 (4)
0 ≤ β <0.6 (5)
0.9 <s + t + u ≦ 1.1 (6)
0 ≦ s ≦ 1.1 (7)
0 ≦ t ≦ 1.1 (8)
0 ≦ u ≦ 1.1 (9)

The above oxide may be the main component of the dielectric thin film 40. When the composition of the oxide contained in the dielectric thin film 40 is represented by the above chemical formula 1a or chemical formula 1b, the oxide content in the dielectric thin film 40 may be 70 mL% or more and 100 mL% or less. As long as the perovskite structure of the oxide is not impaired, the dielectric thin film 40 may contain other elements in addition to Bi, element E1, element E2, Ti and O. That is, the dielectric thin film 40 may contain subcomponents or trace impurities in addition to the above oxides. For example, the dielectric thin film 40 may further contain at least one element of Cr (chromium) and Mo (molybdenum). The dielectric thin film 40 includes Sc (scandium), Y (yttrium), La (lantern), Ce (cerium), Pr (placeodium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europyum). , Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (yttrium) and Lu (lutetium) at least one rare earth element. It may further contain elements. Since the dielectric thin film 40 further contains rare earth elements, the DC bias characteristics of the dielectric thin film 40 can be easily improved.

The thickness of the dielectric thin film 40 may be, for example, 0.01 μm or more and 2 μm or less (10 nm or more and 2000 nm or less). However, the thickness of the dielectric thin film 40 is not limited. The thickness of the dielectric thin film 40 may be measured by observing the cross section of the thin film capacitor 100 with a scanning electron microscope (SEM). The cross section of the thin film capacitor 100 may be formed by excavating the thin film capacitor 100 with a focused ion beam (FIB).

(substrate)
The composition of the substrate 10 is not limited as long as the substrate 10 has sufficient mechanical strength to support the adhesive film 20, the lower electrode 30, the dielectric thin film 40, and the upper electrode 50 formed on the substrate 10. The substrate 10 may be, for example, a single crystal substrate, a ceramic polycrystalline substrate, or a metal substrate. The single crystal substrate includes, 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 or NdGaO. It may consist of ₃ single crystals. The ceramic polycrystalline substrate may consist of, for example, Al ₂ O ₃ polycrystalline, Zn O polycrystalline, or SiO ₂ polycrystalline. The metal substrate is made of, for example, Ni (nickel), Cu (copper), Ti (titanium), W (tungsten), Mo (molybdenum), Al (aluminum), Pt (platinum), or an alloy containing these metals. It may be. Si single crystals are preferable because they are inexpensive and easy to process. When the substrate 10 has sufficient conductivity, the dielectric thin film 40 may directly overlap the surface of the substrate, and the substrate 10 may function as an electrode.

The thickness of the substrate 10 may be, for example, 10 μm or more and 5000 μm or less. However, the thickness of the substrate 10 is not limited. If the substrate 10 is too thin, it is difficult for the substrate 10 to have sufficient mechanical strength. If the substrate 10 is too thick, the thickness of the thin film capacitor 100 as a whole increases, and it is difficult to mount the thin film capacitor 100 on a small electronic component.

The electrical resistivity of the substrate 10 differs depending on the material of the substrate 10. When the electrical resistivity of the substrate 10 is low, the electric current leaks to the substrate 10 when the thin film capacitor 100 is operated, and the electrical characteristics of the thin film capacitor 100 are impaired. For example, when the substrate 10 is made of a Si single crystal, a current may leak to the substrate 10. Therefore, when the electrical resistivity of the substrate 10 is low, the surface of the substrate 10 may be covered with an insulating film, and the adhesive film 20 or the lower electrode 30 may overlap the surface of the insulating film. The insulating film suppresses the leak current. As long as the substrate 10 and the capacitor portion 60 are insulated from each other, the composition and thickness of the insulating film are not limited. Insulating film, for _example, it may consist of SiO 2, _Al 2 _{O 3} or _Si 3 _{N x.} The thickness of the insulating film may be, for example, 0.01 μm or more and 10 μm or less. The insulating film is not essential for the thin film capacitor 100. That is, the adhesive film 20 or the lower electrode 30 may directly overlap the surface of the substrate 10.

(Adhesion film)
By arranging the adhesive film 20 between the substrate 10 and the lower electrode 30, peeling of the lower electrode 30 from the substrate 10 is suppressed. The composition of the adhesive film 20 is not limited as long as the peeling of the lower electrode 30 from the substrate 10 is suppressed. The adhesive film 20 may include, for example, at least one selected from the group consisting of Cr, Ti, TiO ₂ , SiO ₂ , Y ₂ O ₃ and ZrO ₂ . The adhesive film is not essential for the thin film capacitor 100. When the lower electrode 30 easily adheres directly to the substrate 10 or the insulating film, the lower electrode 30 may directly overlap the substrate 10 or the insulating film.

(Lower electrode)
As long as the lower electrode 30 has sufficient conductivity, the composition of the lower electrode 30 is not limited. The lower electrode 30 is, for example, Pt (platinum), Ru (lutenium), Rh (rodium), Pd (palladium), Ir (iridium), Au (gold), Ag (silver), Cu (copper), Ni (nickel). ), An alloy containing these metals, or a conductive oxide. As long as the lower electrode 30 functions as an electrode, the thickness of the lower electrode 30 is not limited. The thickness of the lower electrode 30 may be, for example, 0.01 μm or more and 10 μm or less.

(Upper electrode)
The composition of the upper electrode 50 is not limited as long as the upper electrode 50 has sufficient conductivity. The upper electrode 50 is, for example, Pt (platinum), Ru (lutenium), Rh (rodium), Pd (palladium), Ir (iridium), Au (gold), Ag (silver), Cu (copper), Ni (nickel). ), An alloy containing these metals, or a conductive oxide. As long as the upper electrode 50 functions as an electrode, the thickness of the upper electrode 50 is not limited. The thickness of the upper electrode 50 may be, for example, 0.01 μm or more and 10 μm or less.

(Protective layer)
By covering the lower electrode 30, the dielectric thin film 40 and the upper electrode 50 with the protective film 70, the lower electrode 30, the dielectric thin film 40 and the upper electrode 50 are blocked from the outside atmosphere. As a result, oxidation of the lower electrode 30 and the upper electrode 50 and corrosion of the dielectric thin film 40 are suppressed. The protective film 70 also suppresses damage to the thin film capacitor. As long as the protective film 70 has the above functions, the composition of the protective film 70 is not limited. The protective film 70 may be made of a thermosetting resin such as an epoxy resin, for example.

(Manufacturing method of dielectric thin film and thin film capacitor)
The dielectric thin film and 40 and the thin film capacitor 100 may be manufactured by the following manufacturing methods.

The adhesive film 20 is formed on the surface (main surface) of the substrate 10, and the lower electrode 30 is formed on the surface of the adhesive film 20. The method for forming the adhesive film 20 and the lower electrode 30 may be, for example, a sputtering method, a vacuum vapor deposition method, a printing method, a spin coating method, or a sol-gel method.

When a Si single crystal substrate is used as the substrate 10, an insulating film may be formed on the surface of the substrate 10 before the adhesion film 20 and the lower electrode 30 are formed. The method for forming the insulating film may be, for example, a thermal oxidation method or a CVD (Chemical Vapor Deposition) method.

After the lower electrode 30 is formed, the substrate 10, the adhesive film 20, and the lower electrode 30 may be heat-treated. The heat treatment improves the adhesion between the adhesion film 20 and the lower electrode 30. The heating rate of the heat treatment may be preferably 10 ° C./min or more and 2000 ° C./min or less, and more preferably 100 ° C./min or more and 1000 ° C./min or less. The temperature of the heat treatment is preferably 400 ° C. or higher and 800 ° C. or lower. The heat treatment time is preferably 0.1 hour or more and 4.0 hours or less. When each condition of the heat treatment is out of the above range, it is difficult to improve the adhesion between the adhesion film 20 and the lower electrode 30, and it is difficult for the surface of the lower electrode 30 to become flat. As a result, the dielectric properties of the dielectric thin film 40 are likely to be impaired.

By depositing Bi, element E1, element E2, Ti and O on the surface of the lower electrode 30, the dielectric thin film 40 is formed on the surface of the lower electrode 30. The method for forming the dielectric thin film 40 includes, for example, a vacuum vapor deposition method, a sputtering method, a pulsed laser deposition method (PLD), a metal-organic chemical vapor deposition method (MOCVD), and an organic metal. It may be a decomposition method (Metalorganic Decomposition; MOD), a sol-gel method, or a chemical solution deposition (CSD). The composition of the whole raw material may be adjusted so that the composition of the whole raw material used in the above-mentioned forming method substantially matches the above-mentioned chemical formula 1a or chemical formula 1b. The above-mentioned [Bi] / [E2] may also be controlled by adjusting the composition of the entire raw material. Multiple types of raw materials may be used. The raw material may contain trace impurities or subcomponents as long as the dielectric properties of the dielectric thin film 40 are not impaired.

When the dielectric thin film 40 is formed by a sputtering method, a target having a composition substantially matching the above chemical formula 1a or chemical formula 1b may be produced. As long as the whole target raw material contains Bi, element E1, element E2 and Ti, the target raw material is not limited. The target may be made from a plurality of raw materials. The raw material of the target may be, for example, at least one compound selected from the group consisting of carbonates, oxides, and hydroxides. After the powder of each compound is weighed according to the composition of the dielectric thin film 40, the powder of each compound is mixed. The mixing method may be, for example, a ball mill. The powder of each compound may be mixed with water or an organic solvent. A molded product is obtained by molding the mixed powder under pressure. The molding pressure may be, for example, 10 Pa or more and 200 Pa or less.

A target (sintered body) is obtained by firing the molded product in an oxidizing atmosphere. The firing temperature may be, for example, 900 ° C. or higher and 1300 ° C. or lower. The firing time may be, for example, 1 hour or more and 10 hours or less. The oxidative atmosphere may be, for example, the atmosphere. The shape and dimensions of the target may be adjusted by processing the target. The target may be, for example, a disk.

The dielectric thin film 40 is preferably formed by a high frequency sputtering method (Radio-Frequency Sputtering). In the high-frequency sputtering method, the substrate 10 on which the adhesion film 20 and the lower electrode 30 are laminated is installed in the vacuum chamber. The inside of the vacuum chamber is filled with a mixed gas of Ar (argon) and O ₂ (oxygen). Ar ratio of the volume V2 volume V1 and _{O 2} of (V1 / V2) may preferably be 1/1 or more 5/1 or less. The high frequency power may be preferably 150 W or more and 1000 W or less. High-frequency power is power for applying an AC voltage between a vacuum chamber (anode) and a target (cathode). Due to the sufficiently high high-frequency power, twins of oxide are likely to be formed. If the high frequency power is too small, it is difficult to form the dielectric thin film 40 containing twins of oxide. The temperature of the substrate 10 in the high-frequency sputtering method may be preferably room temperature or higher and 200 ° C. or lower.

After the formation of the dielectric thin film 40, rapid thermal annealing (RTA) of the dielectric thin film 40 may be performed. In RTA, after the temperature of the dielectric thin film 40 rises to the annealing temperature T at the temperature rising rate Vt, the dielectric thin film 40 continues to be heated at the annealing temperature T. The temperature rising rate Vt of RTA is preferably 300 ° C./min or more and 3000 ° C./min or less. Due to the sufficiently high rate of temperature rise Vt, the oxide crystals in the dielectric thin film 40 are likely to grow rapidly, and lattice mismatch is likely to be formed in the oxide crystals. As a result, oxide twins are likely to be formed. Since twins of oxides are easily formed, the annealing temperature T is preferably 700 ° C. or higher and 1000 ° C. or lower. Since twin crystals of oxide are easily formed, the annealing time of the dielectric thin film 40 is preferably 0.5 minutes or more and 5 minutes or less. The annealing time is the time during which the temperature of the dielectric thin film 40 is maintained at the annealing temperature T. In RTA, it is preferable that the dielectric thin film 40 is heated in the atmosphere or an oxidative atmosphere.

By the above method, a dielectric thin film 40 containing twins of oxide is formed. As described above, twins of oxides are formed only by performing high frequency sputtering and RTA under predetermined conditions. In the conventional thick film method (sintering method), a ceramic thick film is formed by sintering the dielectric powder, so the formation of oxide twins is controlled by the thick film method (sintering method). It's difficult to do.

After RTA, the upper electrode 50 is formed on the surface of the dielectric thin film 40. The upper electrode 50 may be formed by the same method as the lower electrode 30.

After the formation of the upper electrode 50, the lower electrode 30, the dielectric thin film 40, and the protective film 70 covering the upper electrode 50 may be formed. The method of forming the protective film 70 is not limited. For example, the lower electrode 30, the dielectric thin film 40, and the upper electrode 50 may be covered with an uncured thermosetting resin, and then the protective film 70 may be formed by heating the thermosetting resin. The lower electrode 30, the dielectric thin film 40, and the upper electrode 50 may be covered with a semi-cured product of a thermosetting resin, and then the protective film 70 may be formed by heating the semi-cured product.

Although preferred embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments. Various modifications of the present invention can be made without departing from the spirit of the present invention, and examples of these modifications are also included in the present invention.

For example, the thin film capacitor may further include another dielectric thin film laminated on the dielectric thin film 40. Another dielectric thin film may be an amorphous dielectric thin film such as Si ₃ N _x , SiO _x , Al ₂ O _x , ZrO _x , or Ta ₂ O _x . By laminating another dielectric thin film on the dielectric thin film 40, it is easy to adjust the impedance and temperature characteristics of the dielectric thin film 40. As long as the thin film capacitor includes at least a pair of electrodes and a dielectric thin film 40 arranged between the pair of electrodes, the structure of the thin film capacitor is not limited to the structure shown in FIG.

The electronic component including the dielectric thin film 40 may be a piezoelectric element. The piezoelectric element may be, for example, a piezoelectric microphone, a harvester, an oscillator, a resonator, or an acoustic multilayer film. The piezoelectric element may be, for example, a piezoelectric actuator. Piezoelectric actuators may be used, for example, in head assemblies, head stack assemblies, or hard disk drives. The piezoelectric actuator may be used, for example, in a printer head or an inkjet printer device. Piezoelectric actuators may be used in piezoelectric switches. The piezoelectric element may be, for example, a piezoelectric sensor. The piezoelectric sensor may be, for example, a gyro sensor, a pressure sensor, a pulse wave sensor, an ultrasonic sensor, or a shock sensor. The electronic component including the dielectric thin film 40 may be a pyroelectric element such as an infrared detector. Each of the electronic components described above may be part or all of a microelectromechanical systems (MEMS).
(Electronic circuit board)
The electronic circuit board according to this embodiment may include the above-mentioned dielectric thin film. The electronic circuit board may include the above electronic components including a dielectric thin film. For example, the electronic circuit board may include the thin film capacitor as an electronic component. Electronic components such as thin film capacitors may be installed on the surface of the electronic circuit board. Electronic components such as thin film capacitors may be embedded in the electronic circuit board. An example of the electronic circuit board is shown in (a) in FIG. 7 and (b) in FIG. The electronic circuit board 90 includes an epoxy-based resin substrate 92, a resin layer 93 covering the epoxy-based resin substrate 92, a thin film capacitor 91 installed on the resin layer 93, and an insulating coating covering the resin layer 93 and the thin film capacitor 91. A layer 94, an electronic component 95 installed on the insulating coating layer 94, and a plurality of metal wirings 96 may be provided. At least a part of the metal wiring 96 may be drawn out to the surface of the epoxy resin substrate 92 or the insulating coating layer 94. At least a part of the metal wiring 96 may be connected to the extraction electrode of the thin film capacitor 91 or the electronic component 95. At least a part of the metal wiring 96 may penetrate the electronic circuit board 90 in the direction from the front surface to the back surface of the electronic circuit board 90.
As shown in FIG. 7B, the thin film capacitor 91 according to the present embodiment includes a lower electrode 30, a dielectric thin film 40 provided on the surface of the lower electrode 30, and a part of the dielectric thin film 40. The upper electrode 50 provided on the upper surface, the penetrating electrode 52 provided directly on the surface of the lower electrode 30 penetrating the other portion of the dielectric thin film 40, and the upper electrode 50, the dielectric thin film 40, and the penetrating electrode 52 An insulating resin layer 58 that covers the insulating resin layer 58, a take-out electrode 54 that penetrates the insulating resin layer 58 and is directly provided on the surface of the through electrode 52, and a take-out electrode 54 that penetrates the insulating resin layer 58 and is directly provided on the surface of the upper electrode 50. The take-out electrode 56 may be provided.
The electronic circuit board 90 may be manufactured by the following procedure. First, the surface of the epoxy resin substrate 92 is covered with an uncured resin layer. The uncured resin layer is a precursor of the resin layer 93. The thin film capacitor 91 is installed on the surface of the uncured resin layer so that the base electrode of the thin film capacitor 91 faces the uncured resin layer. By covering the uncured resin layer and the thin film capacitor 91 with the insulating coating layer 94, the thin film capacitor 91 is sandwiched between the epoxy resin substrate 92 and the insulating coating layer 94. The resin layer 93 is formed by thermosetting the uncured resin layer. The insulating coating layer 94 is pressure-bonded to the epoxy resin substrate 92, the thin film capacitor 91, and the resin layer 93 by hot pressing. A plurality of through holes penetrating the laminated substrate are formed. Metal wiring 96 is formed in each through hole. After forming the metal wiring 96, the electronic component 95 is installed on the surface of the insulating coating layer 94. By the above method, the electronic circuit board 90 embedded in the thin film capacitor 91 can be obtained. Each metal wiring 96 may be made of a conductor such as Cu. The uncured resin layer may be a B-stage thermosetting resin (for example, epoxy resin or the like). The B-stage thermosetting resin is not completely cured at room temperature, but is completely cured by heating. The insulating coating layer 94 may be formed of an epoxy resin, a polytetrafluoroethylene resin, a polyimide resin, or the like.

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

(Example 1)
<Making a target>
The target, which is the raw material of the dielectric thin film, was prepared by the following solid-phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, sodium carbonate, strontium carbonate and titanium oxide. The powders of bismuth oxide, sodium carbonate, strontium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1A. That is, 1-x and x in the chemical formula 1A were adjusted to the values shown in Table 1 below, and [Bi] / [E2] were the values shown in Table 1 below. The definitions of [Bi] / [E2] are as described above. Based on x in Chemical Formula 1A, [Bi] / [E2] is represented as {(1-x) x 0.5} / x.
(1-x) Bi _0.5 Na _0.5 TiO _3- xSrTiO ₃ (1A)

The BNT described below means Bi _0.5 Na _0.5 TiO ₃ . The ST described below means SrTiO ₃ .

A slurry was prepared by mixing the above mixed powder and water with a ball mill for 20 hours. By drying this slurry at 100 ° C., the mixed powder was recovered. A molded product was obtained by molding the mixed powder with a press machine. The molding pressure was 100 Pa. The temperature of the mixed powder during molding was 25 ° C. The time for pressurizing the mixed powder was 3 minutes.

A sintered body was obtained by firing the molded body in air. The firing temperature was 1100 ° C. The firing time was 5 hours.

A disk-shaped target was produced by processing the sintered body. A surface grinder and a cylindrical grinder were used to process the sintered body. The diameter of the target was 80 mm and the thickness of the target was 5 mm.

<Manufacturing of dielectric thin films and thin film capacitors>
As the substrate, a wafer made of a single crystal of Si was used. The thickness of the substrate was 500 μm. By heating the substrate in an oxidizing gas, an insulating film made of SiO ₂ was formed on the surface of the substrate. The thickness of the insulating film was adjusted to 500 nm.

An adhesive film made of Cr was formed on the surface of the substrate (insulating film) by the sputtering method. The thickness of the adhesive film was adjusted to 20 nm. A lower electrode made of Pt was formed on the surface of the adhesion film by the sputtering method. The thickness of the lower electrode was adjusted to 100 nm.

A dielectric thin film was formed on the surface of the lower electrode by the high frequency sputtering method using the above target. In the high-frequency sputtering method, a substrate on which an insulating film, an adhesive film and a lower electrode are laminated is installed in a vacuum chamber. The inside of the vacuum chamber was filled with a mixed gas of Ar and O ₂ . The air pressure in the vacuum chamber was maintained at 1.0 Pa. Ar ratio of the volume V2 volume V1 and _{O 2} of (V1 / V2) was 3/1. The high frequency power was 300 W. The temperature of the substrate 10 in the vacuum chamber was maintained at 100 ° C. The thickness of the dielectric thin film was adjusted to 300 nm.

After the formation of the dielectric thin film, a rapid heating annealing treatment (RTA) of the dielectric thin film was performed. In RTA, the dielectric thin film was heated in the atmosphere. In RTA, after the temperature of the dielectric thin film rose to the annealing temperature T at the heating rate Vt, the dielectric thin film 40 continued to be heated at the annealing temperature T. The temperature rising rate Vt of RTA was 900 ° C./min. The annealing temperature T was 900 ° C. The annealing time of the dielectric thin film was 1 minute.

After RTA, an upper electrode made of Pt was formed on the surface of the dielectric thin film by the sputtering method. By masking, a circular upper electrode was formed. The diameter of the upper electrode was adjusted to 200 μm. The thickness of the upper electrode was adjusted to 100 nm.

By the above method, the dielectric thin film and the thin film capacitor of Example 1 were produced.

<Analysis of Dielectric Thin Films and Thin Film Capacitors>
[Analysis of composition and crystal structure of dielectric thin film]
The X-ray diffraction (XRD) pattern of the dielectric thin film of Example 1 was measured. An X-ray diffractometer (SmartLab) manufactured by Rigaku Co., Ltd. was used for the measurement of the XRD pattern. The XRD pattern showed that the dielectric thin film had a perovskite structure.

The composition of the dielectric thin film of Example 1 was analyzed by X-ray Fluorescence (XRF) analysis. The results of the analysis showed that the composition of the dielectric thin film matched the composition represented by the above chemical formula 1A, and 1-x and x in the chemical formula 1A corresponded to the values shown in Table 1 below.

Twenty fields of view of the dielectric thin film of Example 1 were photographed by a transmission electron microscope (TEM). The dimensions of each field of view photographed were 35 nm in length × 35 nm in width. Fast Fourier transform of each of the 20 images gave 20 FFT patterns. The fast Fourier transform of each image was performed by software (Gatan Microscopic Suite) manufactured by GATAN. Of the 20 FFT patterns, in 5 FFT patterns, the spots corresponding to each crystal orientation were separated into spots S1 and S2. That is, twins were detected in 5 out of 20 locations. The crystal lattice image of the portion where the twins were formed is shown in FIG. The FFT pattern corresponding to the crystal lattice image shown in FIG. 5 is shown in (a) in FIG. 6 and (b) in FIG. Each of 100, 200, 011, 111, and 211 in (a) of FIG. 6 is an index related to the crystal orientation in the perovskite structure. 000 corresponds to the origin for defining the position of each spot. FIG. 6B is an enlarged view of spots S1 and S2 corresponding to 211 shown in FIG. 6A.

The above analysis results showed that the dielectric thin film of Example 1 was an oxide represented by the above chemical formula 1A, the oxide had a perovskite structure, and the oxide contained twins. ..

[Evaluation of DC bias characteristics]
The capacitance C1 of the thin film capacitor of Example 1 was measured in a state where a DC electric field was not applied to the dielectric thin film. As the capacitance measuring device, a digital LCR meter (4284A) manufactured by Hewlett-Packard Co., Ltd. was used. Various measurement conditions for the capacitance C1 are shown below.
Measurement temperature: 25 ° C
Measurement frequency: 1 kHz
Input signal level (measured voltage): 1.0 Vrms
DC electric field (DC bias) strength: 0V / μm

The relative permittivity εr1 of the dielectric thin film of Example 1 was calculated from the capacitance C1, the effective area of the electrodes (the area of the upper electrode), the distance between the electrodes, and the dielectric constant ε _{0 of the} vacuum. That is, the relative permittivity εr1 of the dielectric thin film in a state where the DC electric field is not applied to the dielectric thin film was calculated. Εr1 of Example 1 is shown in Table 1 below. There is no unit of relative permittivity.

The capacitance C2 of the thin film capacitor of Example 1 was measured in a state where a DC electric field was applied to the dielectric thin film. The strength of the DC electric field was 10 V / μm. Except for the strength of the DC electric field, the various measurement conditions of the capacitance C2 were the same as the various measurement conditions of the capacitance C1. From the capacitance C2, the relative permittivity εr2 of the dielectric thin film of Example 1 was calculated. That is, the relative permittivity εr2 of the dielectric thin film in the state where the DC electric field is applied to the dielectric thin film was calculated. The calculation method of εr2 was the same as the calculation method of εr1 except for the capacitance. Εr2 of Example 1 is shown in Table 1 below. εr2 is preferably 600 or more.

[Evaluation of temperature characteristics]
The thin film capacitor of Example 1 was installed in a constant temperature bath. The capacitance of the thin film capacitor at each temperature was continuously measured while continuously changing the temperature of the thin film capacitor in the constant temperature bath from −55 ° C. to 85 ° C. Various measurement conditions of capacitance at each temperature are shown below.
Measurement frequency: 1 kHz
Input signal level (measured voltage): 1.0 Vrms
DC electric field (DC bias) strength: 0V / μm

The relative permittivity at each temperature was calculated from the capacitance at each temperature. The method of calculating the relative permittivity at each temperature was the same as the method of calculating εr1 except for the capacitance. Based on the relative permittivity at each temperature, the rate of change Δεr of the relative permittivity was calculated. Δεr is defined by the following mathematical formula a. The unit of Δεr is%. Εr (25 ° C.) in the equation a is the relative permittivity at 25 ° C. εr (T) is the relative permittivity having the largest difference from εr (25 ° C.) in absolute value among all the relative permittivity measured in the above temperature range. Δεr of Example 1 is shown in Table 1 below. Δεr is preferably −15% or more and 15% or less.
Δεr = 100 × {εr (T) −εr (25 ° C)} / εr (25 ° C) (a)

(Examples 2 to 4)
In the preparation of the targets of Examples 2 to 4, 1-x and x in the chemical formula 1A were adjusted to the values shown in Table 1 below, and [Bi] / [E2] were the values shown in Table 1 below. Met. Dielectric thin films and thin film capacitors of Examples 2 to 4 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin films and thin film capacitors of Examples 2 to 4 were analyzed in the same manner as in Example 1. In any of the cases of Examples 2 to 4, the composition of the dielectric thin film corresponds to the composition represented by the above chemical formula 1A, and 1-x and x in the chemical formula 1A correspond to the values shown in Table 1 below. did. In any of the cases 2 to 4, the dielectric thin film was an oxide represented by the above chemical formula 1A, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr, respectively, of Examples 2 to 4 are shown in Table 1 below.

(Comparative Example 1)
The high frequency power in the high frequency sputtering method of Comparative Example 1 was 100 W. The temperature rising rate Vt of the RTA of Comparative Example 1 was 100 ° C./min. The annealing time in the RTA of Comparative Example 1 was 10 minutes. The dielectric thin film and the thin film capacitor of Comparative Example 1 were produced in the same manner as in Example 3 except for these matters (method for forming the dielectric thin film).

The dielectric thin film and the thin film capacitor of Comparative Example 1 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Comparative Example 1 matched the composition represented by the above chemical formula 1A, and 1-x and x in the chemical formula 1A corresponded to the values shown in Table 1 below. The oxide of Comparative Example 1 had a perovskite structure. However, in the FFT pattern of Comparative Example 1, the spots corresponding to each crystal orientation were not separated. That is, the twin crystals of the oxide were not detected in the dielectric thin film of Comparative Example 1. Εr1, εr2 and Δεr of Comparative Example 1 are shown in Table 1 below.

(Example 11)
The target of Example 11 was prepared by the following solid phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, sodium carbonate, barium carbonate and titanium oxide. The powders of bismuth oxide, sodium carbonate, barium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1B. That is, 1-x and x in the chemical formula 1B were adjusted to the values shown in Table 2 below, and [Bi] / [E2] were the values shown in Table 2 below. Based on x in formula 1B, [Bi] / [E2] is represented as {(1-x) x 0.5} / x. The BT described below means BaTIO ₃ .
(1-x) Bi _0.5 Na _0.5 TiO _3- xBaTiO ₃ (1B)

The dielectric thin film and the thin film capacitor of Example 11 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin film and the thin film capacitor of Example 11 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Example 11 corresponded to the composition represented by the above chemical formula 1B, and 1-x and x in the chemical formula 1B corresponded to the values shown in Table 2 below. The dielectric thin film of Example 11 was an oxide represented by the above chemical formula 1B, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr of Example 11 are shown in Table 2 below.

(Example 12)
The target of Example 12 was prepared by the following solid phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, sodium carbonate, calcium carbonate and titanium oxide. The powders of bismuth oxide, sodium carbonate, calcium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1C. That is, 1-x and x in the chemical formula 1C were adjusted to the values shown in Table 2 below, and [Bi] / [E2] were the values shown in Table 2 below. Based on x in Chemical Formula 1C, [Bi] / [E2] is represented as {(1-x) x 0.5} / x. The CT described below means CaTIO ₃ .
(1-x) Bi _0.5 Na _0.5 TiO _3- xCaTIO ₃ (1C)

The dielectric thin film and the thin film capacitor of Example 12 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin film and the thin film capacitor of Example 12 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Example 12 corresponded to the composition represented by the above chemical formula 1C, and 1-x and x in the chemical formula 1C corresponded to the values shown in Table 2 below. The dielectric thin film of Example 12 was an oxide represented by the above chemical formula 1C, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr of Example 12 are shown in Table 2 below.

(Example 13)
The target of Example 13 was prepared by the following solid phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, potassium carbonate, barium carbonate and titanium oxide. The powders of bismuth oxide, potassium carbonate, barium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1D. That is, 1-x and x in the chemical formula 1D were adjusted to the values shown in Table 2 below, and [Bi] / [E2] were the values shown in Table 2 below. Based on x in formula 1D, [Bi] / [E2] is represented as {(1-x) x 0.5} / x. The BKT described below means Bi _0.5 K _0.5 TiO ₃ .
(1-x) Bi _0.5 K _0.5 TiO _3- xBaTiO ₃ (1D)

The dielectric thin film and the thin film capacitor of Example 13 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin film and the thin film capacitor of Example 13 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Example 13 corresponded to the composition represented by the above chemical formula 1D, and 1-x and x in the chemical formula 1D corresponded to the values shown in Table 2 below. The dielectric thin film of Example 13 was an oxide represented by the above chemical formula 1D, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr of Example 13 are shown in Table 2 below.

(Example 14)
The target of Example 14 was prepared by the following solid phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, potassium carbonate, strontium carbonate, and titanium oxide. The powders of bismuth oxide, potassium carbonate, strontium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1E. That is, 1-x and x in the chemical formula 1E were adjusted to the values shown in Table 2 below, and [Bi] / [E2] were the values shown in Table 2 below. Based on x in formula 1E, [Bi] / [E2] is represented as {(1-x) x 0.5} / x.
(1-x) Bi _0.5 K _0.5 TiO _3- xSrTiO ₃ (1E)

The dielectric thin film and the thin film capacitor of Example 14 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin film and the thin film capacitor of Example 14 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Example 14 corresponded to the composition represented by the above chemical formula 1E, and 1-x and x in the chemical formula 1E corresponded to the values shown in Table 2 below. The dielectric thin film of Example 14 was an oxide represented by the above chemical formula 1E, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr of Example 14 are shown in Table 2 below.

(Example 15)
The target of Example 15 was prepared by the following solid phase method.

A mixed powder was prepared by mixing powders of bismuth oxide, potassium carbonate, calcium carbonate and titanium oxide. The powders of bismuth oxide, potassium carbonate, calcium carbonate and titanium oxide were weighed so that the composition of the mixed powder matched the following chemical formula 1F. That is, 1-x and x in the chemical formula 1F were adjusted to the values shown in Table 2 below, and [Bi] / [E2] were the values shown in Table 2 below. Based on x in the chemical formula 1F, [Bi] / [E2] is expressed as {(1-x) × 0.5} / x.
(1-x) Bi _0.5 K _0.5 TiO _3- xCaTIO ₃ (1F)

The dielectric thin film and the thin film capacitor of Example 15 were produced in the same manner as in Example 1 except for the composition of the target.

The dielectric thin film and the thin film capacitor of Example 15 were analyzed in the same manner as in Example 1. The composition of the dielectric thin film of Example 15 corresponded to the composition represented by the above chemical formula 1F, and 1-x and x in the chemical formula 1F corresponded to the values shown in Table 2 below. The dielectric thin film of Example 15 was an oxide represented by the above chemical formula 1F, the oxide had a perovskite structure, and the oxide contained twins. Εr1, εr2 and Δεr of Example 15 are shown in Table 2 below.

The dielectric thin film according to the present invention is used, for example, in a thin film capacitor.

10 ... Substrate, 20 ... Adhesive film, 30 ... Lower electrode, 40 ... Dielectric thin film, 50 ... Upper electrode, 90 ... Electronic circuit board, 91, 100 ... Thin film capacitor, uc ... Perovskite structure unit cell, tw ... Oxide Twin crystals.

Claims (7)

Contains oxides with a perovskite structure
The oxide contains Bi, element E1, element E2, and Ti.
The element E1 is at least one element selected from the group consisting of Na and K.
The element E2 is at least one element selected from the group consisting of Ca, Sr, and Ba.
The oxide contains twins,
Dielectric thin film. The Bi content in the dielectric thin film is expressed as [Bi] mol%.
The total content of the element E2 in the dielectric thin film is expressed as [E2] mol%.
[Bi] / [E2] is 0.214 or more and 4.500 or less.
The dielectric thin film according to claim 1. The dielectric thin film according to claim 1 or 2.
Electronic components. The dielectric thin film according to claim 1 or 2.
Thin film capacitor. The dielectric thin film according to claim 1 or 2.
Electronic circuit board. The electronic component according to claim 3 is provided.
Electronic circuit board. The thin film capacitor according to claim 4 is provided.
Electronic circuit board.