Capacitance element, electronic component, and method of manufacturing capacitance element

Abstract

To provide a capacitance element or the like having a dielectric with a high relative dielectric constant.SOLUTION: A capacitor element has a dielectric containing β-sialon having a composition expressed by an atomic ratio of Si6-zAlzOzN8-z, and the dielectric has a relative permittivity of 12 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a capacitive element, an electronic component, and a method for manufacturing a capacitive element. [Background technology]

[0002] As digital devices become more sophisticated, higher capacitance is required for capacitors, and this can be achieved by making the dielectric layer thinner.

[0003] Patent Document 1 describes an invention related to a capacitor. The capacitor described in Patent Document 1 has a structure generally called a trench capacitor. In the example of Patent Document 1, a dielectric layer is made of SiO2 doped with impurities. The relative dielectric constant of the region where the doped impurities are not diffused is approximately 3.9, and the relative dielectric constant of the region where the doped impurities are diffused is 3.9 to 7. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7036210 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a capacitance element or the like having a dielectric with a high relative dielectric constant. [Means for solving the problem]

[0006] The capacitance element of the present invention is made of Si 6-z Al z O z N 8-z The dielectric material includes a β-sialon having a composition represented by The dielectric constant of the dielectric is 12 or more.

[0007] The capacitance element of the present invention may satisfy 0.3≦z≦4.2.

[0008] The capacitance element of the present invention may satisfy 2.0≦z≦4.2.

[0009] An electronic component according to the present invention includes the above-described capacitive element.

[0010] The method for manufacturing a capacitor element of the present invention includes a step of forming the dielectric film at a substrate temperature of 400°C or higher and 800°C or lower. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a thin film capacitor according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0013] A schematic diagram of a thin film capacitor, which is a type of capacitance element according to this embodiment, is shown in Figure 1. The thin film capacitor 1 shown in Figure 1 has a lower electrode 12 and a thin film 13 made of a dielectric formed in this order on a substrate 11, and an upper electrode 14 on the surface of the thin film 13 made of a dielectric. In other words, the thin film capacitor 1 has two electrodes that can apply a voltage to the dielectric. In the following description, the thin film made of a dielectric may be simply referred to as a dielectric thin film.

[0014] The term "thin film" as used in this embodiment refers to a thin film formed by separating or exciting a raw material compound used in thin film production at the atomic or molecular level and then re-forming the compound. Therefore, compounds formed into a film by coating a slurry or the like are not included in the thin film as used in this embodiment.

[0015] There are no particular restrictions on the material of the substrate 11, but using a Si single crystal substrate as the substrate 11 is easy to obtain and cost-effective.

[0016] There is no particular limitation on the materials of the lower electrode 12 and the upper electrode 14, as long as they function as electrodes. For example, Pt, Ag, Ni, etc. can be mentioned. The thickness of the lower electrode 12 is preferably 0.01 to 10 μm. The thickness of the upper electrode 14 is preferably 0.01 to 10 μm.

[0017] There is no particular limitation on the thickness of the dielectric thin film 13. For example, it may be 1 nm or more and 1000 nm or less.

[0018] The dielectric contained in the dielectric thin film 13 according to this embodiment is Si in terms of atomic ratio 6-z Al z O z N 8-z and contains β - sialon having a composition represented by. And the relative permittivity is 12 or more. Since the relative permittivity of the dielectric is 12 or more, the thin - film capacitor 1 has a high capacitance. It is more preferable that the relative permittivity is 16 or more.

[0019] Hereinafter, a method for determining whether the dielectric contained in the dielectric thin film 13 according to this embodiment contains β - sialon having a composition represented by Si in terms of atomic ratio 6-z Al z O z N 8-z will be described.

[0020] First, measure the content ratios of Si, Al, O, and N contained in the dielectric thin film 13 based on the number of atoms. There is no particular limitation on the measurement method. For example, it may be measured by ESCA (Electron Spectroscopy for Chemical Analysis).

[0021] Let the content ratio of Si be C1, the content ratio of Al be C2, the content ratio of O be C3, and the content ratio of N be C4. Then z1 = 6×C2 / (C1 + C2), and z2 = 8×C3 / (C3 + C4).

[0022] And when z1 - z2 is greater than - 1.0 and less than 1.0, and 0.0 < z1 < 6.0, then in terms of atomic ratio Si 6-z Al z Oz N 8-z It is assumed that it contains β - sialon having a composition represented by

[0023] In this embodiment, in terms of atomic ratio, Si 6-z Al z O z N 8-z When it contains β - sialon having a composition represented by, z is regarded as equal to z1. 0.0 < z < 6.0. It may be 0.1 ≤ z ≤ 5.9, it may be 0.3 ≤ z ≤ 4.2, or it may be 2.0 ≤ z ≤ 4.2. Particularly, when 2.0 ≤ z ≤ 4.2, the relative permittivity is likely to be improved.

[0024] There is no particular limitation on the content ratio of elements other than Si, Al, O, and N in the dielectric thin film 13. For example, it may be 97 at% or less in total, or it may be 5 at% or less. However, the total content of elements that become fluorescence centers such as Eu may be 3 at% or less, or it may be 0.1 at% or less.

[0025] Hereinafter, by specifying the manufacturing method of the dielectric as a specific manufacturing method, the reason why the relative permittivity of the dielectric containing β - sialon having the above composition can be made a high value of 12 or more will be explained.

[0026] Generally, the mechanism by which a ferroelectric material exhibits ferroelectricity is classified into a displacement type and a disorder - order type. A dielectric that exhibits ferroelectricity by the displacement - type mechanism is called a displacement - type ferroelectric, and a dielectric that exhibits ferroelectricity by the disorder - order type mechanism is called a disorder - order type ferroelectric.

[0027] Most of the generally known ferroelectric materials are displacement - type ferroelectrics. In a displacement - type ferroelectric, ferroelectricity is exhibited by the displacement of cations and / or anions, resulting in a charge bias. A typical displacement - type ferroelectric is barium titanate (BaTiO3). In barium titanate, Ti is displaced by an applied voltage, resulting in a charge bias and the manifestation of ferroelectricity.

[0028] In order-disorder ferroelectrics, ferroelectricity is exhibited when cations and / or anions take an ordered (regular) arrangement. Typical order-disorder ferroelectrics include Rochelle salt (KNaC4H4O6·4H2O) and potassium dihydrogen phosphate (KH2PO4). In Rochelle salt and potassium dihydrogen phosphate, ferroelectricity is exhibited when H takes an ordered arrangement.

[0029] Even in paraelectrics, which are dielectrics that do not exhibit ferroelectricity, dielectric properties are exhibited by the above-mentioned displacement mechanism and / or order-disorder mechanism.

[0030] For example, in dielectrics containing silicon dioxide (SiO2), the coordination center Si forms a tetrahedron surrounded by four O atoms. The length of the Si-O bond (bond distance) changes slightly with applied voltage, resulting in an accumulated charge. In other words, silicon dioxide exhibits dielectric properties through a displacement mechanism. On the other hand, silicon dioxide does not substantially exhibit dielectric properties through an order-disorder mechanism.

[0031] Here, it is believed that a dielectric material containing β-sialon having the above composition and having an ordered arrangement of O and N, as will be described later, exhibits dielectric properties through both the displacement mechanism and the order-disorder mechanism, resulting in a significant increase in the dielectric constant of the dielectric material. Specifically, it is believed that the dielectric constant of the dielectric material will be 12 or more.

[0032] When no voltage is applied to a dielectric containing β-sialon, each atom is in thermal motion. When a voltage is applied to a dielectric containing β-sialon, the atoms in thermal motion are slightly displaced, resulting in the manifestation of dielectric properties. For example, the slight displacement of the coordination centers Si and Al in β-sialon results in the manifestation of dielectric properties. This manifestation of dielectric properties is due to a displacement mechanism.

[0033] The oxide of Si is represented by SiO2, and the oxide of Al is represented by Al2O3. Furthermore, the nitride of Si is represented by Si3N4. Therefore, the Si and Al contained in β-sialon are not equivalent, and the O and N contained in β-sialon are not equivalent.

[0034] In dielectrics containing β-sialon, the application of voltage causes the divalent O and trivalent N to exchange positions, resulting in the manifestation of dielectric properties through an order-disorder mechanism.

[0035] As described above, the β-sialon according to this embodiment has an atomic ratio of Si 6-z Al z O z N 8-z In other words, the ratio of Si, Al, O, and N is uniquely expressed by z. In other words, the crystal is made up of a stoichiometric composition of each atom. Until now, the arrangement of each atom in crystals containing β-sialon has rarely been discussed.

[0036] Normally, O and / or N contained in β-sialon are coordinated to Si and / or Al, which are coordination centers. As a result, O and / or N are shared between Si atoms, between Al atoms, or between Si and Al. It is difficult for O and N, which are shared at the coordination center, to simply exchange positions.

[0037] The inventors discovered that by crystallizing β-sialon while applying an appropriate amount of energy, O and N atoms are arranged in an orderly manner. They also discovered that when multiple tetra- or hexa-coordinated units are formed in an orderly manner, the orderly formed multiple tetra- or hexa-coordinated units move in unison upon application of voltage, allowing O and N atoms to exchange positions relatively easily.

[0038] On the other hand, when the Si, Al, O, and N contained in β-sialon are arranged randomly, the O and N do not exchange positions sufficiently even when a voltage is applied. This is because, as mentioned above, it is difficult for the O and N atoms shared at the coordination center to simply exchange positions, and because the tetra- or hexa-coordinated units are not formed in an orderly manner, it is also difficult for the entire tetra- or hexa-coordinated unit to move in unison.

[0039] Furthermore, when unequal atoms form a crystal with a stoichiometric composition, the orderly arrangement of the atoms is believed to be the most stable. Therefore, a crystal structure formed by the orderly formation of 4- or 6-coordinate units formed by the coordination of O and N with Si and Al is believed to be highly stable.

[0040] From the above, the present inventors have found that a dielectric having a high dielectric constant can be obtained by depositing a thin film having a dielectric containing β-sialon while suitably controlling the substrate temperature during film deposition. On the other hand, the present inventors have found that the degree of orderly arrangement of Si, Al, O, and N contained in β-sialon can be estimated from the magnitude of the dielectric constant.

[0041] There are no particular limitations on the shape of the crystals of β-sialon contained in dielectric thin film 13. β-sialon may be in a microcrystalline state close to amorphous.

[0042] Manufacturing method of thin film capacitor 1 Next, a method for manufacturing the thin film capacitor 1 will be described.

[0043] There are no particular limitations on the method for forming the thin film that will ultimately become the dielectric thin film 13. Examples include vacuum deposition, sputtering, MO-CVD (metal organic chemical vapor deposition), MOD (metal organic decomposition), sol-gel, CSD (chemical solution deposition), and ALD (atomic layer deposition). The raw materials used during film formation may contain trace impurities or minor components, but this is not a problem as long as the amounts are not significant enough to impair the performance of the thin film. The dielectric thin film 13 according to this embodiment may also contain trace impurities or minor components to the extent that they do not significantly impair the performance.

[0044] Among the above film formation methods, when a film is formed by a method such as sputtering, the finally obtained dielectric tends to have a dielectric constant of at least 12. In this embodiment, a film formation method using sputtering will be described.

[0045] First, the substrate 11 is prepared. There are no particular restrictions on the material of the substrate 11. For example, using a Si single crystal substrate is easy to obtain and cost-effective. When flexibility is important, a metal foil, such as a Ni foil, can also be used as the substrate. When a metal foil is used as the substrate 11, the substrate 11 may also serve as the lower electrode 12.

[0046] Next, if the substrate 11 does not also serve as the lower electrode 12, the lower electrode 12 is formed on the substrate 11. There is no particular limitation on the material of the lower electrode 12, as long as it functions as an electrode. Examples include Pt, Ag, and Ni. There is no particular limitation on the thickness of the lower electrode. When the lower electrode 12 is formed on the substrate 11, it may be 0.01 to 10 μm. There is no particular limitation on the method of forming the lower electrode 12. Examples include sputtering and vapor deposition.

[0047] Next, the dielectric thin film 13 is formed on the lower electrode 12. A method for forming the dielectric thin film 13 by sputtering will be described below.

[0048] First, a target is prepared. There are no particular limitations on the method for preparing the target, and known methods can be used. There are no particular limitations on the type of target, and in addition to metal oxide sintered bodies containing Al and Si, which are the constituent elements of the dielectric thin film 13 to be prepared, alloys, nitride sintered bodies, metal oxynitride sintered bodies, etc. can be used. Furthermore, it is preferable that each element is evenly distributed in the target, but the distribution may vary as long as it does not affect the quality of the resulting dielectric thin film 13. Furthermore, it is not necessary to use only one target, and it is also possible to prepare and use multiple targets containing some of the constituent elements of the dielectric thin film 13 for film formation. There are also no particular limitations on the shape of the target, and it is sufficient to use a shape that is suitable for the film formation apparatus to be used.

[0049] Next, a substrate 11 on which a target and a lower electrode 12 are formed is placed in a chamber. Then, power is applied to the target while Ar gas is supplied into the chamber. At this time, O2 gas and N2 gas are simultaneously supplied into the chamber along with the Ar gas. The substrate 11 is then heated. This allows the deposition of a dielectric thin film 13 containing β-sialon. The temperature of the substrate 11 is set to 400°C to 800°C. It may also be set to 500°C to 700°C. When the temperature of the substrate 11 during deposition is set to 400°C to 800°C, multiple tetra- or hexa-coordinated units formed by O and N coordinating with the coordination centers Si and Al are likely to be formed in an orderly fashion. Furthermore, when the temperature is too high, β-sialon particle crystals are likely to be formed. There is no particular limit to the magnitude of the power applied to the target. For example, it may be set to 100W to 300W. The sputtering time is set to a time required to obtain the desired thickness of the dielectric thin film 13. Annealing may be performed after deposition.

[0050] Ar gas is also used in forming a normal dielectric thin film, and if Ar gas is not supplied, it is difficult to form the dielectric thin film 13. There is no particular limit to the amount of Ar gas supplied.

[0051] When an alloy is used as the target, O2 gas and N2 gas, which are reactive gases, are supplied simultaneously with Ar gas. If O2 gas and / or N2 gas are not supplied, O and / or N are not supplied, and β-sialon is not formed. Furthermore, when a metal oxide sintered body is used as the target, it is essential to supply at least N2 gas, and when a metal nitride sintered body is used as the target, it is essential to supply at least O2 gas.

[0052] There are no particular limitations on the supply rates of O2 gas and N2 gas. They may each be, for example, 0 to 100 sccm (excluding 0). Changing the supply rates of these gases also changes the value of z in the β-sialon contained in the resulting dielectric thin film 13.

[0053] Finally, the thin film capacitor 1 can be manufactured by forming an upper electrode 14 on the dielectric thin film 13. There is no particular limitation on the material of the upper electrode 14, and Ag, Au, Cu, etc. can be used. There is also no particular limitation on the method for forming the upper electrode 14. For example, it can be formed by sputtering.

[0054] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be embodied in various different forms without departing from the spirit of the present invention.

[0055] The capacitive element according to the present invention refers to an element that utilizes dielectric properties, and includes capacitors, condensers, filters, memories, etc. The capacitive element according to the present invention is preferably used as a capacitive element that is required to have a high relative dielectric constant even when the thickness of the dielectric thin film is thin. The capacitive element according to the present invention also includes a substrate-embedded capacitive element. The capacitive element according to the present invention also includes a capacitive element having a trench structure.

[0056] The electronic components according to the present invention include capacitor chips, multilayer capacitors, thin film capacitors, embedded capacitors, capacitors formed directly on a substrate, etc. The capacitance element according to the present invention is suitable for use in electronic components that require a high relative dielectric constant even when the thickness of the dielectric thin film is thin. [Example]

[0057] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0058] Example 1 In Example 1, a metal target made of an alloy in which the atomic ratio was Al:Si=50:50 was prepared as a film formation target.

[0059] Next, a film formation target was placed in a film formation apparatus, and a Si substrate was placed facing the film formation target. The Si substrate had a Pt film on its surface as a lower electrode. Two Si substrates were prepared: one for measuring the dielectric constant and the other for measuring the composition.

[0060] Then, a film was formed on both substrates by sputtering to a thickness of 44 nm. The time required for film formation was 0.5 hours. During film formation, the substrate was placed on the ceiling of the chamber, and the substrate was heated from the back side (the side opposite to the side in contact with the Pt film) using a lamp. The substrate temperature during film formation was 500°C. Film formation was performed while flowing Ar gas, N2 gas, and O2 gas into the chamber. The flow rates of N2 gas and O2 gas were controlled so that the composition of the β-sialon would be as shown in Table 1. In Example 1, specifically, the flow rate of N2 gas was 80 sccm, and the flow rate of O2 gas was 0.5 sccm.

[0061] The composition of the obtained dielectric thin film was confirmed. Specifically, the composition of the dielectric thin film formed on the substrate for composition measurement was measured by ESCA while Ar etching was performed along the film thickness direction. Almost no composition deviation was observed along the film thickness direction. The composition measured by ESCA is shown in Table 1.

[0062] Furthermore, an Ag film was formed as an upper electrode on the surface of the dielectric thin film formed on the substrate for measuring the relative permittivity.The relative permittivity was then measured using an LCR meter.The results are shown in Table 1.

[0063] [Table 1]

[0064] As can be seen from Table 1, the dielectric thin film obtained under the production conditions of Example 1 contained β-sialon having a composition within a specific range, and had a relative dielectric constant of 12 or more.

[0065] (Example 2, Comparative Examples 1 to 9) The film formation temperature (substrate temperature during film formation) was changed from that of Example 1 as shown in Table 1, and various conditions were changed so that the content of each element in the dielectric thin film and z were the values ​​shown in Table 1.

[0066] Comparative Examples 1 to 4 were carried out in the same manner as Example 1, except that the film formation temperature, N2 gas flow rate, and O2 gas flow rate were changed. The N2 gas flow rate was changed within the range of 0 to 100 sccm, and the O2 gas flow rate was changed within the range of 0.1 to 10 sccm.

[0067] Example 2 was carried out in the same manner as Example 1, except that a film formation target prepared by placing an Al chip on a Si metal target was used.

[0068] Comparative Examples 5 and 6 were carried out in the same manner as in Example 1, except that a Si metal target was used as the film formation target. Comparative Examples 7 to 9 were carried out in the same manner as in Example 1, except that an Al metal target was used as the film formation target.

[0069] In Example 2, the dielectric thin film contained β-sialon having a composition within a specific range, and had a relative dielectric constant of 12 or more. In contrast, in Comparative Examples 1 to 9, the dielectric thin film did not contain β-sialon, and had a relative dielectric constant of less than 12.

[0070] (Examples 11 to 14) The experiment was carried out under the same conditions as in Example 1, except that the ratio of Si to Al in the film formation target was varied and the flow rates of N2 gas and O2 gas were also varied. The ratio of Si to Al in the film formation target was controlled by selecting either a metal target made of an Al:Si=50:50 alloy or a Si metal target, and by selecting the number of Al chips to be placed on the selected metal target. The flow rate of N2 gas was varied within the range of 10 to 100 sccm, and the flow rate of O2 gas was varied within the range of 0.1 to 10 sccm. The results are shown in Table 2.

[0071] [Table 2]

[0072] From Table 2, it can be seen that when the dielectric thin film contained β-sialon having a composition within a specific range, the relative dielectric constant was 12 or more.

[0073] (Examples 15 to 18, Comparative Examples 11 to 14) Dielectric thin films were formed under the same conditions as in Example 1 or 2, except that the film formation temperature was changed. In Examples 15 and 16 and Comparative Examples 11 and 12, the composition was adjusted to be similar to that of Example 1, particularly in terms of the z value (value of z1). In Examples 17 and 18 and Comparative Examples 13 and 14, the composition was adjusted to be similar to that of Example 2, particularly in terms of the z value. The results are shown in Table 2.

[0074] As can be seen from Table 2, when the film formation temperature was within the preferred range, a dielectric thin film containing β-sialon and having a relative dielectric constant of 12 or more was obtained. When the film formation temperature was either too low or too high, a dielectric thin film containing β-sialon was obtained, but the relative dielectric constant was less than 12.

[0075] It is presumed that if the film formation temperature is too low, the crystallinity of the β-sialon is too low and the O and N atoms do not have a sufficiently ordered arrangement, resulting in a low dielectric constant.If the film formation temperature is too high, the stress within the dielectric thin film is too great, making it difficult for the entire 4- or 6-coordinate units to move in unison, resulting in a low dielectric constant.

[0076] In particular, in the examples where the film formation temperature was 500° C. or higher and 700° C. or lower and 2.0≦z≦4.2 was satisfied, the relative dielectric constant was 16 or higher. [Explanation of symbols]

[0077] 1. Thin film capacitor 11... Substrate 12. Bottom electrode 13. Thin film made of dielectric (dielectric thin film) 14...Top electrode

Claims

1. Atomic ratio: Si 6-z Al z O z N 8-z The dielectric material includes a β-sialon having a composition represented by A capacitance element in which the dielectric has a relative dielectric constant of 12 or more.

2. 2. The capacitance element according to claim 1, wherein 0.3≦z≦4.2 is satisfied.

3. 2. The capacitance element according to claim 1, wherein z satisfies 2.0≦z≦4.

2.

4. An electronic component comprising the capacitive element according to any one of claims 1 to 3.

5. 4. The method for manufacturing a capacitance element according to claim 1, further comprising the step of depositing the dielectric film at a substrate temperature of 400° C. or higher and 800° C. or lower.

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