Dielectric, laminate, capacitor, electrical circuit, circuit board, and device

Abstract

A dielectric 10 includes a tantalum compound containing fluorine and oxygen. The tantalum compound satisfies the conditions of 0 < x < 2.5 and 0.08 < y ≤ 0.2. x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound. y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound.

Description

Dielectrics, laminates, capacitors, electric circuits, circuit boards, and devices

[0001] The present disclosure relates to dielectrics, laminates, capacitors, electric circuits, circuit boards, and devices.

[0002] Tantalum compounds containing fluorine and oxygen are known.

[0003] For example, Patent Document 1 describes a dielectric material containing an amorphous tantalum compound containing fluorine and oxygen, which has a higher dielectric constant than a dielectric material not containing fluorine.

[0004] Patent Document 2 describes a capacitor including metallic tantalum, a conductor, and a tantalum oxide film. The tantalum oxide film is disposed in contact with the metallic tantalum and is disposed between the metallic tantalum and the conductor. The tantalum oxide film includes a first portion containing fluorine and a second portion. The second portion is located closer to the metallic tantalum than the first portion in the thickness direction of the tantalum oxide film. The fluorine concentration in the second portion is lower than the fluorine concentration in the first portion.

[0005] Patent No. 7122617 International Publication No. 2023 / 234343

[0006] The present disclosure provides a dielectric that is advantageous from the viewpoint of increasing the withstand voltage.

[0007] The dielectric of the present disclosure includes a tantalum compound containing fluorine and oxygen, wherein the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, where x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound.

[0008] According to the present disclosure, it is possible to provide a dielectric that is advantageous from the viewpoint of increasing the withstand voltage.

[0009] FIG. 1 is a cross-sectional view showing an example of a laminate of the present disclosure. FIG. 2 is a cross-sectional view showing an example of a capacitor of the present disclosure. FIG. 3 is a cross-sectional view showing another example of a capacitor of the present disclosure. FIG. 4A is a diagram schematically showing an example of an electric circuit of the present disclosure. FIG. 4B is a diagram schematically showing an example of a circuit board of the present disclosure. FIG. 4C is a diagram schematically showing an example of an apparatus of the present disclosure. FIG. 5 is a graph showing the results of X-ray diffraction (XRD) measurements of a sample according to Example 2 and metal tantalum. FIG. 6 is a graph showing the relationship between the withstand voltage of the dielectric film of the samples according to each Example and each Comparative Example and the fluorine content in the tantalum compound. FIG. 7 is a graph showing the relationship between the normalized Q value of the samples according to each Example and each Comparative Example and the fluorine content in the tantalum compound.

[0010] (Knowledge Forming the Basis of the Present Disclosure) For example, there is a continuous demand for improving the processing performance of electronic devices. The performance of electronic components such as capacitors significantly affects the performance of electronic devices incorporating those components. For this reason, it is expected that there will be an increasing need for capacitors that are small and can exhibit high performance. For example, electrolytic capacitors are known as capacitors. In electrolytic capacitors, a dielectric consisting of a thin oxide film is formed on the surface of metallic aluminum or metallic tantalum by chemical conversion treatment of aluminum or tantalum. In electrolytic capacitors, attempts have been made to increase the capacitance mainly by increasing the specific surface area of ​​the dielectric. However, such attempts have limitations, and it is believed that the performance of capacitors can be further improved if dielectric materials with higher dielectric constants and higher withstand voltages can be developed. In addition, such dielectric materials are also considered promising as materials for transistor gate insulating films.

[0011] According to Patent Document 1, a dielectric containing fluorine-containing amorphous tantalum oxide exhibits a higher relative dielectric constant than a dielectric containing fluorine-free tantalum oxide. The composition of this fluorine-containing amorphous tantalum oxide is TaO x F yIn this composition, a high relative dielectric constant can be exhibited in the ranges of 0<x<2.5 and 0<y≦0.4. Thus, by using fluorine-containing tantalum oxide in a capacitor, it is expected that the capacitance of the capacitor will be increased.

[0012] According to Patent Document 2, the dielectric layer is obtained by anodizing tantalum in an aqueous solution containing fluorine ions. Patent Document 2 shows that there are conditions under which the dielectric loss tangent of the anodic oxide film becomes high. Furthermore, Patent Document 2 shows that the dielectric loss tangent of the fluorine-containing amorphous tantalum oxide dielectric is reduced by anodizing tantalum in a fluorine-free aqueous solution and then performing additional anodization in a fluorine-containing aqueous solution. According to Patent Document 2, the fluorine-containing amorphous tantalum oxide is converted into TaO x F y When expressed as a composition, the conditions 0<x<2.5 and 0.015≦y≦0.4 are satisfied. Thus, by using a specific fluorine-containing tantalum oxide in a capacitor, it is expected that the dielectric loss tangent of the capacitor can be reduced. Note that a low dielectric loss tangent of the dielectric is advantageous in order to reduce the loss of electrical energy in a capacitor.

[0013] On the other hand, in order to improve the performance of a capacitor, it is also important to increase the withstand voltage of the dielectric. For example, if the withstand voltage of the dielectric is high, the operating voltage of the capacitor can be increased. Alternatively, the same operating voltage as before can be achieved even if the thickness of the dielectric is made thinner. Reducing the thickness of the dielectric can also increase the capacitance of the capacitor.

[0014] In view of these circumstances, the present inventors have conducted extensive research into the voltage resistance characteristics of tantalum compounds containing fluorine and oxygen. As a result, the present inventors have newly discovered that the voltage resistance of a dielectric can be increased by adjusting the fluorine content in a tantalum compound containing fluorine and oxygen. Based on this new finding, the present inventors have completed the dielectric of the present disclosure.

[0015] (Embodiments) Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0016] FIG. 1 is a cross-sectional view showing an example of a laminate of the present disclosure. As shown in FIG. 1, the laminate 1a includes a dielectric 10. The dielectric 10 includes a tantalum compound containing fluorine and oxygen. The tantalum compound is, for example, amorphous. The tantalum compound may include a crystalline material. This tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2. In these conditions, x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound. In addition, y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound. When the dielectric 10 includes such a tantalum compound, the dielectric 10 tends to have a high withstand voltage.

[0017] The tantalum compound preferably satisfies the condition 0.08<y≦0.16. In this case, the withstand voltage of the dielectric 10 is likely to be high, and the capacitance of a capacitor including the dielectric 10 is likely to be high. Therefore, in a capacitor including the dielectric 10, the Q value, which is the product of the capacitance [F] and the withstand voltage [V], which is an index showing the performance of the capacitor, is likely to be high.

[0018] The tantalum compound is, for example, TaO x F y The tantalum compound may contain impurity elements other than tantalum, fluorine, and oxygen. The content of the impurity elements in the tantalum compound is, for example, 5 atomic % or less.

[0019] 1, the dielectric 10 is, for example, a film. The dielectric 10 is, for example, an anodized film. The dielectric 10 can be obtained, for example, by bringing an anode and a cathode containing metallic tantalum into contact with a solution containing a fluoride, and then generating a current between the anode and the cathode to perform anodization.

[0020] 1 , the laminate 1a further includes metal tantalum 20, and the dielectric 10 is in contact with the surface of the metal tantalum 20. The metal tantalum 20 forms, for example, the surface of a substrate that supports the film formed by the dielectric 10.

[0021] Fig. 2 is a cross-sectional view showing an example of a capacitor according to the present disclosure. As shown in Fig. 2, capacitor 2a includes a first electrode 21, a second electrode 22, and a dielectric 10. Dielectric 10 is disposed between first electrode 21 and second electrode 22. Dielectric 10 has the same structure as dielectric 10 in laminate 1a described above. Capacitor 2a includes dielectric 10, and thus is likely to have a high withstand voltage and can exhibit desired performance.

[0022] The first electrode 21 contains, for example, metal tantalum 20. The first electrode 21 may contain a valve metal other than tantalum, or may contain gold, platinum, copper, or the like.

[0023] The second electrode 22 may contain an electrolyte solution or a conductive polymer. The second electrode 22 may contain a conductor used in an upper electrode disposed across a dielectric from a lower electrode disposed near the base material of a circuit board on which the capacitor 2 a is mounted.

[0024] The first electrode 21 has, for example, a principal surface 21p. One principal surface of the dielectric 10 is in contact with, for example, the principal surface 21p. The second electrode 22 has a principal surface 22p parallel to the principal surface 21p. The other principal surface of the dielectric 10 is in contact with, for example, the principal surface 22p.

[0025] Fig. 3 is a cross-sectional view showing another example of a capacitor according to the present disclosure. Capacitor 2b shown in Fig. 3 has the same configuration as capacitor 2a, except for portions that will be specifically described. Components of capacitor 2b that are the same as or correspond to those of capacitor 2a are designated by the same reference numerals, and detailed descriptions thereof will be omitted. The description of capacitor 2a also applies to capacitor 2b, unless technically inconsistent.

[0026] 3, in capacitor 2b, first electrode 21 contains metal tantalum 20, at least a portion of which is porous. With this configuration, the surface area of ​​metal tantalum 20 tends to be large, and capacitor 2b tends to have a high capacitance. Such a porous structure can be formed, for example, by etching a metal foil and sintering a powder.

[0027] The dielectric 10 is disposed on the surface of the porous portion of the metal tantalum 20. As described above, the dielectric 10 is, for example, an anodic oxide film.

[0028] 3, the capacitor 2b further includes an electrolyte 23. The electrolyte 23 is disposed between the first electrode 21 and the second electrode 22. With this configuration, the capacitor 2b is more likely to have a high capacitance.

[0029] The electrolyte 23 is not limited to a specific electrolyte. For example, the electrolyte 23 includes at least one selected from the group consisting of an electrolytic solution, a solid electrolyte, and a conductive polymer. Examples of the conductive polymer include polypyrrole, polythiophene, polyaniline, and derivatives thereof. The electrolyte may also be a manganese compound such as manganese oxide.

[0030] The electrolyte 23 is disposed, for example, so as to fill voids around the porous portion of the metal tantalum 20. The second electrode 22 may include, for example, a solidified silver-containing paste, a carbon material such as graphite, or both the above-mentioned solidified paste and a carbon material.

[0031] 4A is a diagram schematically illustrating an example of an electric circuit according to the present disclosure. The electric circuit 3 includes a capacitor 2a. The electric circuit 3 may be an active circuit or a passive circuit. The electric circuit 3 may be a discharge circuit, a smoothing circuit, a decoupling circuit, or a coupling circuit. Because the electric circuit 3 includes the capacitor 2a, the electric circuit 3 is likely to exhibit the desired performance. For example, noise is likely to be reduced in the electric circuit 3. The electric circuit 3 may also include a capacitor 2b.

[0032] 4B is a diagram schematically illustrating an example of a circuit board according to the present disclosure. As shown in FIG. 4B, the circuit board 5 includes a capacitor 2a. For example, an electric circuit 3 including the capacitor 2a is formed on the circuit board 5. Since the circuit board 5 includes the capacitor 2a, the circuit board 5 is likely to exhibit the desired performance. The circuit board 5 may be an embedded board or a motherboard. The circuit board 5 may also include a capacitor 2b.

[0033] FIG. 4C is a schematic diagram illustrating an example of a device according to the present disclosure. As shown in FIG. 4C , the device 7 includes a capacitor 2a. The device 7 includes, for example, a circuit board 5 including the capacitor 2a. Because the device 7 includes the capacitor 2a, the device 7 is likely to exhibit desired performance. The device 7 may be an electronic device, a communication device, a signal processing device, or a power supply. The device 7 may be a server, an AC adapter, an accelerator, or a flat panel display such as a liquid crystal display (LCD). The device 7 may be a USB charger, a solid-state drive (SSD), an information terminal such as a PC, a smartphone, or a tablet PC, or an Ethernet switch. The device 7 may also include a capacitor 2b.

[0034] The dielectric 10 may be included in, for example, a gate insulating film of a transistor. In other words, it is possible to provide a transistor having a gate insulating film including the dielectric 10. The transistor is, for example, a field effect transistor (FET).

[0035] (Additional Notes) From the above description, the following technologies are disclosed. (Technology 1) A dielectric comprising a tantalum compound containing fluorine and oxygen, wherein the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, where x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound. (Technology 2) A dielectric according to Technology 1, wherein the tantalum compound satisfies the condition of 0.08<y≦0.16. (Technology 3) A dielectric according to Technology 1 or 2, wherein the dielectric is an anodic oxide film. (Technology 4) A dielectric according to any one of Technology 1 to 3, wherein the tantalum compound is amorphous. (Technology 5) The tantalum compound is TaO x F yThe dielectric according to any one of Techniques 1 to 4, having a composition represented by the following formula: (Technology 6) A laminate comprising: metallic tantalum; and a dielectric in contact with a surface of the metallic tantalum, wherein the dielectric includes a tantalum compound containing fluorine and oxygen, and the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, wherein x is a ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is a ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound. (Technology 7) A capacitor comprising a first electrode, a second electrode, and a dielectric disposed between the first electrode and the second electrode, wherein the dielectric comprises a tantalum compound containing fluorine and oxygen, and the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, where x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound. (Technology 8) The capacitor according to Technology 7, further comprising an electrolyte disposed between the first electrode and the second electrode. (Technology 9) The capacitor according to Technology 8, wherein the electrolyte comprises at least one selected from the group consisting of an electrolytic solution, a solid electrolyte, and a conductive polymer. (Technology 10) An electric circuit comprising the capacitor according to any one of Technologies 7 to 9. (Technology 11) A circuit board comprising the capacitor according to any one of Technologies 7 to 9. (Technology 12) A device comprising the capacitor according to any one of Technologies 7 to 9.

[0036] The present disclosure will be described in more detail below with reference to examples. Note that the following examples are illustrative and the present disclosure is not limited to the following examples.

[0037] (Examples 1 to 4) A flat plate of metallic tantalum was immersed in acetone and subjected to ultrasonic cleaning for 10 minutes to clean the surface of the metallic tantalum. The acetone adhering to the surface of the metallic tantalum was then dried using a nitrogen blow, and the surface of the metallic tantalum was washed with pure water. The metallic tantalum was then dried in the atmosphere to obtain an anode foil.

[0038] The anode foil and a metal tantalum plate as a counter electrode were placed at a predetermined distance so that they were immersed in a phosphoric acid aqueous solution. The portion of the anode foil not immersed in the aqueous solution was connected to the positive terminal of a power supply, and the portion of the metal tantalum plate not immersed in the aqueous solution was connected to the negative terminal of the power supply. A voltage of 15 V was applied between the anode foil and the metal tantalum plate for 13 hours, forming an oxide layer containing tantalum oxide on the surface of the anode foil. The anode foil was then removed from the aqueous solution, washed with pure water, and then dried in the air.

[0039] Next, the anode foil with the oxide layer formed thereon and a metal tantalum plate serving as a counter electrode were placed at a predetermined distance so as to be immersed in a mixed aqueous solution of potassium fluoride and potassium phosphate buffer. The portion of the anode foil not immersed in the mixed aqueous solution was connected to the positive terminal of a power supply, and the portion of the metal tantalum plate not immersed in the mixed aqueous solution was connected to the negative terminal of the power supply. A voltage of 45 V was applied between the anode foil and the metal tantalum plate for 4 hours, forming a fluorine-containing tantalum compound layer on the anode foil. The potassium fluoride concentration in the mixed aqueous solution and the potassium phosphate buffer concentration were 0.5 mol / L to 3 mol / L and 0.05 mol / L, respectively. The anode foil was removed from the mixed aqueous solution, washed with pure water, and then dried in the air.

[0040] Next, the anode foil with the fluorine-containing tantalum compound layer formed thereon was heat-treated in air at 260°C for 2 hours. After the heat treatment, the anode foil was allowed to cool to room temperature (20°C to 30°C), and then the anode foil and a metal tantalum plate serving as a counter electrode were placed at a predetermined distance so as to be immersed in an aqueous phosphoric acid solution. The portion of the anode foil not immersed in the aqueous solution was connected to the positive terminal of a power supply, and the portion of the metal tantalum plate not immersed in the aqueous solution was connected to the negative terminal of the power supply. A voltage of 44.5 V was applied between the anode foil and the metal tantalum plate for 30 minutes to perform repair chemical conversion. The anode foil was removed from the aqueous phosphoric acid solution, washed with pure water, and then dried in air. In this manner, samples according to Examples 1 to 4 were obtained, in which a dielectric film containing a tantalum compound containing fluorine and oxygen was formed on the surface of the metal tantalum.

[0041] Comparative Example 1: A flat tantalum foil was immersed in acetone and subjected to ultrasonic cleaning for 10 minutes to clean the surface of the tantalum foil. The acetone adhering to the tantalum foil surface was then dried with nitrogen, and the tantalum foil surface was then washed with pure water. The tantalum foil was then dried in the atmosphere to obtain an anode foil.

[0042] The above-mentioned anode foil and a metal tantalum plate as a counter electrode were placed at a predetermined distance so that they were immersed in a phosphoric acid aqueous solution. The portion of the anode foil not immersed in the aqueous solution was connected to the positive terminal of a power supply, and the portion of the metal tantalum plate not immersed in the aqueous solution was connected to the negative terminal of the power supply. A voltage of 40 V was applied between the anode foil and the metal tantalum plate for 13 hours, forming an oxide layer containing tantalum oxide on the surface of the anode foil. The anode foil was then removed from the aqueous solution, washed with pure water, and then dried in the air. In this way, a sample according to Comparative Example 1 was obtained, in which a dielectric film was formed on the surface of the metal tantalum.

[0043] Comparative Example 2 A sample according to Comparative Example 2 was obtained in the same manner as in Examples 1 to 4, except for the following points: The concentration of potassium fluoride in the mixed aqueous solution used to form the fluorine-containing tantalum compound layer was adjusted to 0.1 mol / L.

[0044] (Elemental Composition Analysis) Pieces of a predetermined size were cut out from the samples according to each Example and Comparative Example, and were embedded in resin to prepare samples for TOF-SIMS. Using a TOF-SIMS device TOF.SIMS5 manufactured by ION-TOF, TOF-SIMS measurements were performed on the samples prepared from the samples according to Example 1 and Comparative Example 1, and composition analysis was performed in the depth direction of the samples. In TOF-SIMS, a Bi ion beam was used as the primary ion beam. O was used as the sputtering ion species. 2+ F in the depth profile of the TOF-SIMS measurement results - , TaO 3- , and O -The fluorine content in the dielectric film of the sample was determined from the signal intensity of the TOF-SIMS measurement results. A calibration curve was used to determine the fluorine content from the TOF-SIMS measurement results. The calibration curve was created based on the measurement results using a Rutherford backscattering spectrometry (RBS) instrument, Pelletron 5SDH-2, and the F content in the TOF-SIMS measurement results was calculated using a calibration curve. - and the signal intensity of TaO x F y The value of y in the tantalum compound represented by the formula:

[0045] (X-ray Diffraction) XRD patterns were obtained by 2θ / θ scanning for the samples prepared from each example using an X-ray diffractometer, X'Pert PRO, manufactured by PANalytical. Cu-Kα radiation was used as the X-ray source, with the voltage adjusted to 45 kV and the current adjusted to 40 mA. The wavelength of Cu-Kα radiation was 0.15418 nm. FIG. 5 is a graph showing the results of X-ray diffraction (XRD) measurements of the sample according to Example 2 and metallic tantalum. In FIG. 5, the vertical axis represents the diffraction intensity in arbitrary units, and the horizontal axis represents the diffraction angle 2θ. As shown in FIG. 5, the results of the XRD measurement of the sample according to Example 2 confirmed diffraction peaks attributable to metallic tantalum, but an overall broad profile was observed. This indicated that the tantalum compound contained in the dielectric film of the sample according to Example 2 was amorphous. Similarly, it was also indicated that the tantalum compounds contained in the dielectric films of the samples according to the other examples were amorphous.

[0046] (Evaluation of Withstand Voltage) Samples according to each example and comparative example were mounted in a plate electrode evaluation cell manufactured by BAS Corporation, and the withstand voltage was evaluated by chronovoltammetry using a phosphoric acid aqueous solution as the electrolyte and platinum as the counter electrode. The constant current value in chronovoltammetry was set to 1 μA, and the voltage value after 5 minutes was taken as the withstand voltage value. The evaluation was carried out at room temperature (20°C to 30°C). The thickness of the dielectric film in each sample was evaluated by spectroscopic ellipsometry. The withstand voltage value [V / nm] was calculated by dividing the withstand voltage value by the thickness of the dielectric film. The results are shown in Table 1.

[0047] 6 is a graph showing the relationship between the withstand voltage of the dielectric film and the fluorine content in the tantalum compound of the samples according to each Example and Comparative Example. In FIG. 6, the vertical axis represents the withstand voltage [V / nm], and the horizontal axis represents the molar ratio y of the fluorine content to the tantalum content in the dielectric film. The composition of the tantalum compound containing fluorine and oxygen in the dielectric film of the sample according to each Example was calculated using the molar ratio y as TaO x F y As shown in Fig. 6, the withstand voltage of the tantalum compound containing fluorine and oxygen that constitutes the dielectric film of the sample according to each example was higher than the withstand voltage of the tantalum oxide that does not contain fluorine that constitutes the dielectric film of the sample according to Comparative Example 1. In addition, the withstand voltage of the tantalum compound containing fluorine and oxygen that constitutes the dielectric film of the sample according to each example was higher than the withstand voltage of the tantalum compound that constitutes the dielectric film of the sample according to Comparative Example 2. Comparing each example with each comparative example, it was found that TaO x F y It can be understood that the dielectric film containing a tantalum compound is likely to have a high withstand voltage when the condition 0.08<y≦0.2 is satisfied in the composition. The tantalum oxide contained in the dielectric film of the sample according to Comparative Example 1 does not contain fluorine, and therefore the tantalum oxide is TaO x F y In the notation, y is 0.

[0048] (Capacity Evaluation) The samples according to each Example and Comparative Example were mounted in a plate electrode evaluation cell manufactured by BAS Corporation, and the capacity was evaluated according to the AC impedance method using a sulfuric acid aqueous solution as the electrolyte and platinum as the counter electrode. The capacity value used in the evaluation was the capacity value at 120 Hz. The evaluation was carried out at room temperature (20°C to 30°C). The results are shown in Table 1.

[0049] 7 is a graph showing the relationship between the normalized Q value of the samples according to each Example and Comparative Example and the fluorine content of the tantalum compound. In FIG. 7, the vertical axis represents the normalized Q value, and the horizontal axis represents the molar ratio y of the fluorine content to the tantalum content in the dielectric film. The normalized Q value is a value obtained by normalizing the Q value, defined as the product of the capacitance determined by the capacitance evaluation and the withstand voltage, by the Q value of the sample according to Comparative Example 1. As shown in FIG. 7, the Q values ​​of the samples according to the Examples were higher than the Q values ​​of the samples according to the Comparative Examples. In particular, TaO x F y It can be understood that in the composition, when the condition 0.08<y≦0.16 is satisfied, the dielectric film tends to have a high withstand voltage and a high Q value.

[0050]

[0051] The dielectric material of the present disclosure can be suitably used in electronic components such as capacitors and transistors.

Claims

1. A dielectric comprising a tantalum compound containing fluorine and oxygen, wherein the tantalum compound satisfies the conditions 0<x<2.5 and 0.08<y≦0.2, where x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound.

2. The dielectric according to claim 1, wherein the tantalum compound satisfies the condition 0.08<y≦0.

16.

3. The dielectric according to claim 1, wherein the dielectric is an anodic oxide film.

4. The dielectric according to claim 1, wherein the tantalum compound is amorphous.

5. The tantalum compound is TaO x F y The dielectric material according to claim 1 , having a composition represented by the formula:

6. A laminate comprising: metallic tantalum; and a dielectric in contact with a surface of the metallic tantalum, wherein the dielectric comprises a tantalum compound containing fluorine and oxygen, and the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, wherein x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound.

7. A capacitor comprising: a first electrode; a second electrode; and a dielectric disposed between the first electrode and the second electrode, wherein the dielectric contains a tantalum compound containing fluorine and oxygen, and wherein the tantalum compound satisfies the conditions of 0<x<2.5 and 0.08<y≦0.2, wherein x is the ratio of the number of oxygen atoms to the number of tantalum atoms in the tantalum compound, and y is the ratio of the number of fluorine atoms to the number of tantalum atoms in the tantalum compound.

8. The capacitor of claim 7, further comprising an electrolyte disposed between the first electrode and the second electrode.

9. The capacitor according to claim 8, wherein the electrolyte includes at least one selected from the group consisting of an electrolytic solution, a solid electrolyte, and a conductive polymer.

10. An electric circuit comprising a capacitor according to any one of claims 7 to 9.

11. A circuit board comprising a capacitor according to any one of claims 7 to 9.

12. An apparatus comprising a capacitor according to any one of claims 7 to 9.

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