Capacitor and method of manufacturing capacitor
The capacitor design with a dielectric layer of dispersed metal oxides achieves a high dielectric constant and reduced leakage current, addressing the challenges of existing capacitors.
Patent Information
- Application Number
- JP2024048686
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-25
- Publication Date
- 2025-10-07
AI Technical Summary
Existing capacitors face challenges in achieving a high dielectric constant while minimizing leakage current and dielectric breakdown.
A capacitor design incorporating a dielectric layer composed of a matrix phase containing a third metal oxide with first and second metal oxides dispersed within, where the electrical conductivity of the second metal oxide is lower than the first, and the third metal oxide is lower than the second, utilizing a mixture of SiO2, ZnO, and Zn2SiO4 formed by sputtering.
The design achieves a high dielectric constant with reduced leakage current and suppressed dielectric breakdown, enhancing capacitance and stability.
Smart Images
Figure 2025148090000001_ABST
Abstract
Description
[Technical Field]
[0001] The present disclosure relates to a capacitor and a method for manufacturing a capacitor, and more particularly to a capacitor including a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode, and a method for manufacturing the same. [Background technology]
[0002] Patent Document 1 describes an oxide insulator film that contains a first metal oxide and a second metal oxide having a lower electrical conductivity than the first metal oxide, and that is configured such that the first metal oxide is dispersed in a matrix phase that also contains the second metal oxide, and a capacitor that includes this oxide insulator film. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] International Publication No. 2022 / 054697 Summary of the Invention [Problem to be solved by the invention]
[0004] The object of the present disclosure is to achieve a high dielectric constant for a dielectric layer in a capacitor having a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode. [Means for solving the problem]
[0005] A capacitor according to one embodiment of the present disclosure includes a first electrode, a second electrode, and a dielectric layer interposed between the first and second electrodes. The dielectric layer contains a first metal oxide, a second metal oxide, and a third metal oxide. The dielectric layer includes a matrix phase containing the third metal oxide, and the first and second metal oxides are dispersed in the matrix phase. The electrical conductivity of the second metal oxide is lower than that of the first metal oxide, and the electrical conductivity of the third metal oxide is lower than that of the second metal oxide. Each of the first, second, and third metal oxides contains at least one element selected from the group consisting of Si and Zn.
[0006] In a method for manufacturing a capacitor according to one aspect of the present disclosure, the capacitor includes a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode. The method includes forming the dielectric layer by a sputtering method using a target made of a mixture containing SiO2 and ZnO. In the target, the ratio of Zn atoms to the total of Zn atoms and Si atoms is 20 atomic % or more and 67.5 atomic % or less. [Effects of the Invention]
[0007] According to the present disclosure, in a capacitor including a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode, it is possible to achieve a high dielectric constant for the dielectric layer. [Brief explanation of the drawings]
[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a capacitor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an explanatory diagram showing the relationship between an electric field and polarization occurring in a dielectric layer in the embodiment. [Figure 3] FIG. 3 is an explanatory diagram showing the relationship between an electric field and polarization occurring in a dielectric layer in the embodiment. [Figure 4]FIG. 4 is a cross-sectional view showing an example of a specific configuration of a capacitor in the above embodiment, and the configuration of an evaluation capacitor used in the examples. DETAILED DESCRIPTION OF THE INVENTION
[0009] Hereinafter, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. The following embodiments are merely some of the various embodiments of the present disclosure, and various modifications are possible depending on the design as long as the object of the present disclosure can be achieved. All figures referenced below are schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. Although the mechanism of action related to the embodiments may be described below, the description of the mechanism of action may be based on speculation, and the present disclosure is not bound by the description of the mechanism of action below.
[0010] The capacitor 1 according to the embodiment includes a first electrode 31, a second electrode 32, and a dielectric layer 2 interposed between the first electrode 31 and the second electrode 32. One of the first electrode 31 and the second electrode 32 can function as a cathode of the capacitor 1, and the other can function as an anode of the capacitor 1.
[0011] The dielectric layer 2 contains a first metal oxide, a second metal oxide, and a third metal oxide. The dielectric layer 2 has a matrix phase 23 containing the third metal oxide, and the first metal oxide and the second metal oxide are dispersed in the matrix phase 23. The electrical conductivity of the second metal oxide is lower than that of the first metal oxide, and the electrical conductivity of the third metal oxide is lower than that of the second metal oxide. Each of the first metal oxide, the second metal oxide, and the third metal oxide contains at least one element selected from the group consisting of Si and Zn. That is, each of the first metal oxide, the second metal oxide, and the third metal oxide is an oxide of a metal containing at least one element selected from the group consisting of Si and Zn.
[0012] According to the embodiment, in a capacitor 1 including a first electrode 31, a second electrode 32, and a dielectric layer 2 interposed between the first electrode 31 and the second electrode 32, it is possible to achieve a high dielectric constant for the dielectric layer 2. This can increase the capacitance of the capacitor 1. Furthermore, leakage current is less likely to occur in the dielectric layer 2, which can suppress dielectric breakdown of the capacitor 1. The reasons for this are presumed to be as follows.
[0013] When a voltage is applied between the first electrode 31 and the second electrode 32 of the capacitor 1, an electric field generated within the dielectric layer 2 polarizes the first metal oxide and the second metal oxide. FIGS. 2 and 3 show the polarization of the first particles 21 and the second particles 22 when the dielectric layer 2 includes first particles 21 containing the first metal oxide and second particles 22 containing the second metal oxide. The arrows in FIGS. 2 and 3 indicate the direction of the electric field. As shown in FIGS. 2 and 3, the first particles 21 and the second particles 22 are polarized by the electric field, and the direction of polarization changes accordingly when the direction of the electric field changes. The dispersion of the polarized first metal oxide and second metal oxide in the matrix phase 23 in this manner creates numerous interfaces between the matrix phase 23 and the polarized first metal oxide (first particles 21) and second metal oxide (second particles 22) within the dielectric layer 2. This can increase the dielectric constant of the dielectric layer 2.
[0014] Furthermore, if only one type of metal oxide is dispersed in the matrix phase 23, there is a risk of leakage current due to conduction between the metal oxide particles. In particular, when the dielectric layer 2 is fabricated by a sputtering method, as described below, the volume density of the metal oxide dispersed in the matrix phase 23 increases, which may bring the metal oxide particles closer to each other and increase the leakage current. However, in the embodiment, the electrical conductivity of the second metal oxide is lower than that of the first metal oxide, so that the leakage current caused by the first metal oxide can be inhibited by the second metal oxide. That is, for example, since second particles 22 containing the second metal oxide are likely to be interposed between adjacent first particles 21 containing the first metal oxide, the leakage current between adjacent first particles 21 can be inhibited by the second particles 22. This can suppress the leakage current of the capacitor 1.
[0015] The configuration of the dielectric layer 2 will be described in detail.
[0016] The third metal oxide is preferably SiO2. That is, it is preferable that the matrix phase 23 contains SiO2. In this case, SiO2 has a relatively low electrical conductivity, and therefore leakage current can be further suppressed.
[0017] It is also preferable that the third metal oxide is amorphous. In particular, it is preferable that the third metal oxide is amorphous silica. In this case, the matrix phase 23 has high uniformity, which makes it more difficult for leakage current to occur in the dielectric layer 2. Whether the third metal oxide is amorphous can be confirmed by an appropriate analytical method. For example, if no diffraction peaks due to the crystalline structure of the third metal oxide are observed by X-ray diffraction or electron beam diffraction, it can be confirmed that the third metal oxide is amorphous.
[0018] It is preferable that the dielectric layer 2 includes first particles 21 containing a first metal oxide, and the first particles 21 are dispersed in a matrix phase 23. In this case, a large number of interfaces between the matrix phase 23 and the first particles 21 are formed in the dielectric layer 2, and polarization of the first particles 21 can increase the relative permittivity of the dielectric layer 2.
[0019] It is preferable that the proportion of particles with a particle size of 20 nm or less among the first particles 21 is 90% by number or more. In this case, the relative dielectric constant of the dielectric layer 2 can be increased. This is presumably because polarization occurring at the interface between the first particles 21 and the matrix phase 23 is improved. It is also preferable that the first particles 21 contain particles with a particle size of 1 nm or more. Note that the particle size of the first particles 21 is the particle size of the first particles 21 converted into a perfect circle in an image obtained by observing, for example, a cross section of the dielectric layer 2 using a transmission electron microscope.
[0020] It is also preferable that the dielectric layer 2 includes second particles 22 containing a second metal oxide, and the second particles 22 are dispersed in the matrix phase 23. In this case, a large number of interfaces between the matrix phase 23 and the second particles 22 are formed in the dielectric layer 2, and the dielectric constant of the dielectric layer 2 can be increased due to polarization of the second particles 22.
[0021] It is preferable that the proportion of particles with a particle size of 20 nm or less among the second particles 22 is 90% by number or more. In this case, the relative dielectric constant of the dielectric layer 2 can be increased. This is presumably because polarization occurring at the interface between the second particles 22 and the matrix phase 23 is improved. It is also preferable that the second particles 22 contain particles with a particle size of 1 nm or more. The particle size of the second particles 22 is the particle size of the second particles 22 in terms of a perfect circle in an image obtained by observing, for example, a cross section of the dielectric layer 2 using a transmission electron microscope.
[0022] The first metal oxide is, for example, ZnO. In this case, the first metal oxide has a relatively high electrical conductivity, which can increase the relative dielectric constant of the dielectric layer 2.
[0023] The second metal oxide may be, for example, Zn2SiO4. In this case, the second metal oxide may have a relatively high dielectric constant and a moderately low electrical conductivity. This increases the dielectric constant of the dielectric layer 2 and further reduces the leakage current of the capacitor 1.
[0024] The ratio of Zn atoms to the total of Zn atoms and Si atoms in the dielectric layer 2 is preferably 20 atomic % or more and 67.5 atomic % or less. In this case, a matrix phase 23 containing SiO2, first particles 21 containing ZnO dispersed in the matrix phase 23, and second particles 22 containing Zn2SiO4 dispersed in the matrix phase 23 can be stably formed in the dielectric layer 2. In particular, when the dielectric layer 2 is produced by a sputtering method described later, the matrix phase 23, the first particles 21, and the second particles 22 can be more stably formed.
[0025] The thickness of the dielectric layer 2 is, for example, 100 nm or less. In this case, the capacitance of the capacitor 1 can be increased. A thickness of 50 nm or less is more preferable, and a thickness of 30 nm or less is even more preferable. The thickness of the dielectric layer 2 is, for example, 2 nm or more. In this case, leakage current in the capacitor 1 is less likely to occur. A thickness of 5 nm or more is more preferable, and a thickness of 10 nm or more is even more preferable. The thickness of the dielectric layer 2 is not limited to the above.
[0026] The dielectric layer 2 is formed by, for example, sputtering so as to overlap the substrate. In this case, the dielectric layer 2 can be easily thinned, thereby increasing the capacitance of the capacitor 1. The substrate is, for example, the first electrode 31 or the second electrode 32. For example, RF (Radio Frequency) sputtering is used as the sputtering method. When the dielectric layer 2 is formed by sputtering, the target is a mixed target that is, for example, a mixture containing SiO2 and ZnO. In this case, the dielectric layer 2 can be formed containing ZnO as the first metal oxide, Zn2SiO4 as the second metal oxide, and SiO2 as the third metal oxide. In this case, the ratio of Zn atoms to the total of Zn atoms and Si atoms in the mixed target is preferably 20 atomic % or more and 67.5 atomic % or less. In this case, the matrix phase 23 containing SiO2, the first particles 21 containing ZnO dispersed in the matrix phase 23, and the second particles 22 containing Zn2SiO4 dispersed in the matrix phase 23 can be phase-separated and stably formed in the dielectric layer 2.
[0027] When the dielectric layer 2 is formed by sputtering, a portion of the dielectric layer 2 formed by sputtering may be removed by wet etching or the like to adjust the shape and dimensions of the dielectric layer 2. In this case, the dielectric layer 2 having the desired shape and dimensions can be formed at the desired position on the substrate.
[0028] The first electrode 31 and the second electrode 32 will now be described. Each of the first electrode 31 and the second electrode 32 may be conductive. One of the first electrode 31 and the second electrode 32, or each of the first electrode 31 and the second electrode 32, may contain, for example, a metal or a conductive inorganic metal compound, specifically at least one selected from the group consisting of Ti, Pt, Al, Ni, TiN, Ta, TaN, and Au. Alternatively, one of the first electrode 31 and the second electrode 32, or each of the first electrode 31 and the second electrode 32, may contain a conductive polymer. In this case, one of the first electrode 31 and the second electrode 32, or each of the first electrode 31 and the second electrode 32, may contain only a conductive polymer. The conductive polymer may be applied, for example, when the capacitor 1 is an electrolytic capacitor or a hybrid capacitor. The conductive polymer may include, for example, at least one selected from the group consisting of polypyrrole, polythiophene, polyaniline, and derivatives thereof.
[0029] The first electrode 31 may contain aluminum. When the first electrode 31 contains aluminum, the capacitor 1 may be an electrolytic capacitor or a hybrid capacitor in which the first electrode 31 is an anode and the second electrode 32 is a cathode. When the first electrode 31 contains aluminum, the second electrode 32 preferably contains a conductive polymer. In this case, the ESR (equivalent series resistance) of the capacitor 1 can be reduced. It is also preferable that the second electrode 32 contains an electrolyte. In this case, the life of the capacitor 1 can be extended. It is also preferable that the second electrode 32 contains an electrolyte and a conductive polymer. In this case, the ESR (equivalent series resistance) of the capacitor 1 can be reduced and the life of the capacitor 1 can be extended. It is also preferable that the second electrode 32 contains a semi-solid electrolyte. In this case, the heat resistance of the capacitor 1 can be improved. It is also preferable that the second electrode 32 contains an all-solid electrolyte. In this case, the heat resistance of the capacitor 1 can be improved.
[0030] The materials of the first electrode 31 and the second electrode 32 are not limited to those mentioned above, and may include any appropriate conductive material.
[0031] The thickness of the first electrode 31 is, for example, not less than 0.01 μm and not more than 1 mm. The thickness of the second electrode 32 is, for example, not less than 0.01 μm and not more than 1 mm.
[0032] 4 shows a more specific example of the configuration of capacitor 1. Capacitor 1 includes a first electrode 31 which is an anode, a dielectric layer 2, a second electrode 32 which is a cathode, a protective layer 6, a base insulating layer 5, a substrate 4, a first external electrode 71, and a second external electrode 72.
[0033] The substrate 4 is, for example, a silicon substrate, but is not limited to this.
[0034] The insulating base layer 5 is an electrically insulating layer. The insulating base layer 5 overlaps one of the main surfaces of the substrate 4 and covers this main surface. The insulating base layer 5 contains at least one material selected from the group consisting of, for example, SiN and SiO2. However, the components of the insulating base layer 5 are not limited thereto.
[0035] The second electrode 32 overlaps part of the main surface of the substrate 4 with the base insulating layer 5 interposed therebetween. That is, the second electrode 32 overlaps the surface of the base insulating layer 5 opposite to the substrate 4 side. The second electrode 32 covers part of the base insulating layer 5.
[0036] The dielectric layer 2 overlaps a part of the surface of the second electrode 32 opposite to the substrate 4. In other words, the dielectric layer 2 covers a part of the second electrode 32.
[0037] The protective layer 6 covers the portion of the surface of the base insulating layer 5 opposite to the substrate 4 side that is not covered by the second electrode 32, all but a portion of the portion of the surface of the second electrode 32 opposite to the substrate 4 side that is not covered by the dielectric layer 2, and all but a portion of the surface of the dielectric layer 2 opposite to the substrate 4. The protective layer 6 is made of an electrically insulating resin such as a polyimide resin.
[0038] The first electrode 31 overlaps a portion of the dielectric layer 2 that is not covered with the protective layer 6 on the surface opposite to the substrate 4 side.
[0039] The first external electrode 71 overlaps a portion of the surface of the protective layer 6 opposite the substrate 4, and is electrically connected to the first electrode 31. There may be no boundary between the first electrode 31 and the first external electrode 71, that is, the first electrode 31 and the first external electrode 71 may form an integrated member. The second external electrode 72 overlaps a portion of the surface of the second electrode 32 opposite the substrate 4 that is not covered with the protective layer 6, and is thereby electrically connected to the second electrode 32.
[0040] When manufacturing the capacitor 1, for example, first, a base insulating layer 5 is formed so as to overlap one main surface of the substrate 4. The base insulating layer 5 is formed, for example, by depositing the material of the base insulating layer 5 on the main surface of the substrate 4 by plasma enhanced chemical vapor deposition.
[0041] Next, the second electrode 32 is fabricated so as to overlap a portion of the surface of the base insulating layer 5 opposite the substrate 4. The second electrode 32 is fabricated by an appropriate method depending on the material of the second electrode 32. For example, when the second electrode 32 contains a metal or a conductive inorganic metal compound, the second electrode 32 can be fabricated by a vapor deposition method such as electron beam vapor deposition. When the second electrode 32 contains a conductive polymer, the second electrode 32 can be fabricated, for example, by applying a solution containing the conductive polymer and then drying it. The second electrode 32 may also be fabricated by forming a film of the conductive polymer by electrolytic polymerization.
[0042] Next, the dielectric layer 2 is formed so as to overlap a part of the surface of the second electrode 32 layer opposite to the substrate 4. The dielectric layer 2 is formed, for example, by using the sputtering method and the wet etching method, as already described.
[0043] Next, protective layer 6 is formed so as to cover the portion of base insulating layer 5 on the surface opposite to substrate 4 that is not covered with second electrode 32, all but a portion of the portion of second electrode 32 on the surface opposite to substrate 4 that is not covered with dielectric layer 2, and all but a portion of the surface of dielectric layer 2 on the surface opposite to substrate 4. When protective layer 6 is formed from a polyimide resin, protective layer 6 is formed, for example, by applying photosensitive polyimide, exposing it to light, developing it, and then post-baking it.
[0044] Next, the first electrode 31 is fabricated so as to overlap a portion of the dielectric layer 2 on the surface opposite the substrate 4 side that is not covered by the protective layer 6. At the same time as fabricating the first electrode 31, the first external electrode 71 may be fabricated so as to overlap a portion of the protective layer 6 on the surface opposite the substrate 4 side, and the second external electrode 72 may be fabricated so as to overlap a portion of the second electrode 32 on the surface opposite the substrate 4 that is not covered by the protective layer 6. In this case, the first electrode 31, the first external electrode 71, and the second external electrode 72 are fabricated by an appropriate method depending on their materials. For example, when the first electrode 31, the first external electrode 71, and the second external electrode 72 each contain a metal or a conductive inorganic metal compound, the first electrode 31, the first external electrode 71, and the second external electrode 72 can each be fabricated by a vapor deposition method such as electron beam vapor deposition. When the first electrode 31, the first external electrode 71, and the second external electrode 72 each contain a conductive polymer, the first electrode 31, the first external electrode 71, and the second external electrode 72 can each be produced by, for example, applying a solution containing the conductive polymer and then drying it. The first electrode 31, the first external electrode 71, and the second external electrode 72 may each be produced by forming a film of the conductive polymer by electrolytic polymerization.
[0045] The configuration of capacitor 1 is not limited to the above. Capacitor 1 may have any suitable configuration as long as it includes first electrode 31, dielectric layer 2, and second electrode 32. The materials and manufacturing methods of the elements constituting capacitor 1 are also not limited to those described above. [Example]
[0046] Below, a capacitor 1 for evaluation was fabricated that had a dielectric layer 2, and the dielectric layer 2 was evaluated using this capacitor 1 for evaluation. Note that the present disclosure is not limited to the following examples.
[0047] 1. Examples 1 to 3 and Comparative Example 1 The configuration of the evaluation capacitor 1 is as shown in FIG.
[0048] First, a silicon substrate having a thickness of 350 μm or more was prepared as the substrate 4. This substrate 4 was washed with buffered hydrofluoric acid.
[0049] Next, an insulating base layer 5 made of SiO2 and having a thickness of 300 nm or more was formed on one main surface of the substrate 4 by plasma enhanced chemical vapor deposition.
[0050] Next, a 20 nm thick Ti layer, a 100 nm thick Pt layer, and a 100 nm thick Ti layer were deposited in this order by electron beam evaporation so as to overlap part of the insulating base layer 5. In this way, a second electrode 32, which was a cathode, was produced.
[0051] Next, a dielectric layer 2 having a thickness of 30 nm was formed on the second electrode 32 by RF sputtering under the following conditions. Target: A mixed target containing ZnO and SiO2. Atmosphere: 5% oxygen partial pressure. RF power: 80W or 150W. Distance between the target and the second electrode 32: 80 mm.
[0052] In each of Examples 1 to 3 and Comparative Example 1, the ratio of Zn atoms to the total of Zn atoms and Si atoms contained in the target is as shown in Table 1 in the column "Zn / (Zn+Si) [at %]".
[0053] A part of the dielectric layer 2 was removed by wet etching to adjust the shape and dimensions of the dielectric layer 2.
[0054] Next, a protective layer 6 made of polyimide and having a thickness of 800 nm to 1000 nm was formed so as to overlap the portion of the base insulating layer 5 that was not covered with the second electrode 32, all but a portion of the portion of the second electrode 32 that was not covered with the dielectric layer 2, and all but a portion of the dielectric layer 2. This protective layer 6 was formed by applying photosensitive polyimide, exposing it to light, developing it, and then post-baking it.
[0055] Next, a first electrode 31 was fabricated, overlapping a portion of the dielectric layer 2 that was not covered with the protective layer 6, a first external electrode 71 was fabricated that overlapped a portion of the surface of the protective layer 6 opposite the substrate 4 and was connected to the first electrode 31, and a second external electrode 72 was fabricated that overlapped a portion of the second electrode 32 that was not covered with the protective layer 6. The first electrode 31, first external electrode 71, and second external electrode 72 were fabricated by depositing a 100 nm thick Ti layer and a 100 nm thick Au layer, in this order, by electron beam evaporation.
[0056] In this way, a capacitor 1 for evaluation was produced.
[0057] 2. Comparative Examples 2 to 4 A capacitor 1 for evaluation was fabricated in the same manner as in item 1 above, except that a dielectric layer 2 having a thickness shown in Table 1 was formed on the second electrode 32 by the following method.
[0058] Dielectric layers 2 having the thicknesses shown in Table 1 were fabricated by alternately depositing SiO2 layers and ZnO layers by atomic layer deposition (ALD). In Comparative Example 2, the number of SiO2 layers was 23, each with a thickness of 0.11 nm, and the number of ZnO layers was 23, each with a thickness of 0.34 nm. In Comparative Example 3, the number of SiO2 layers was 14, each with a thickness of 0.44 nm, and the number of ZnO layers was 14, each with a thickness of 0.17 nm. In Comparative Example 4, the number of SiO2 layers was 7, each with a thickness of 0.99 nm, and the number of ZnO layers was 7, each with a thickness of 0.17 nm. In each of Comparative Examples 2 to 4, the ratio of Zn atoms to the total number of Zn atoms and Si atoms contained in dielectric layer 2 is as shown in the column "Zn / (Zn+Si) [at%]" in Table 1.
[0059] 3.Evaluation Test (1) Composition of dielectric layer 2 The dielectric layer 2 in each of Examples 1 to 3 and Comparative Example 1 was cut along a plane perpendicular to the main surface of the substrate 4. Images of the cross section of the dielectric layer 2 were obtained by photographing the cross section using a scanning transmission electron microscope, and the distributions of Si atoms, Zn atoms, and O atoms in the cross section were obtained using an energy dispersive X-ray spectrometer. Furthermore, the crystal structure of the observed particles was identified by electron diffraction analysis of the lattice spacing. As a result, it was confirmed that in Examples 1 to 3, the dielectric layer 2 contained a matrix phase 23 containing SiO2, first particles 21 containing ZnO dispersed in the matrix phase 23, and second particles 22 containing Zn2SiO4 dispersed in the matrix phase 23. In all of Examples 1 to 3, the diameters of the first particles 21 and the second particles 22, as confirmed from the images, were each 20 nm or less in terms of equivalent circular diameter.
[0060] On the other hand, in Comparative Example 1, XRR (X-ray reflectivity measurement) was carried out, and the analysis results suggested that a film in which SiO2 and ZnO were mixed was formed.
[0061] Furthermore, when X-ray diffraction measurements were performed on Examples 1 to 3, diffraction peaks indicating ZnO crystals and Zn2SiO4 crystals were confirmed, but diffraction peaks indicating SiO2 crystals were not confirmed, which indicated that the matrix phase 23 containing SiO2 was amorphous.
[0062] (2) Relative permittivity evaluation In each of Examples 1 to 3 and Comparative Examples 1 to 4, as shown in FIG. 4, the first external electrode 71 and the second external electrode 72 of the evaluation capacitor 1 were connected to an impedance analyzer 8, and the second external electrode 72 was connected to ground. The impedance analyzer 8 was a model E4990A manufactured by Keysight Technologies. Using the impedance analyzer 8, the relative permittivity of the dielectric layer 2 was measured under conditions of a measurement frequency of 1 kHz, an AC voltage (effective value) of 500 mV, and a DC voltage of 0 V. The results are shown in Table 1.
[0063] The literature value of the relative dielectric constant of SiO2 is 3.8, that of Zn2SiO4 is 5.0, and that of ZnO is 8.5. The electrical conductivities of amorphous SiO2, Zn2SiO4, and ZnO are 10 -16 S / cm, 10 -8 S / cm and 10 -3 S / cm.
[0064] [Table 1]
[0065] As shown in Table 1, in Examples 1 to 3 having the configuration of the embodiment, the dielectric layer 2 has a high relative dielectric constant. In Comparative Examples 1 and 2, the dielectric layer 2 was completely conductive, causing a huge leakage current, so the relative dielectric constant could not be measured.
[0066] [Aspect] A capacitor (1) according to a first embodiment comprises a first electrode (31), a second electrode (32), and a dielectric layer (2) interposed between the first electrode (31) and the second electrode (32). The dielectric layer (2) contains a first metal oxide, a second metal oxide, and a third metal oxide. The dielectric layer (2) comprises a matrix phase (23) containing the third metal oxide, and the first metal oxide and the second metal oxide are dispersed in the matrix phase (23). The electrical conductivity of the second metal oxide is lower than that of the first metal oxide, and the electrical conductivity of the third metal oxide is lower than that of the second metal oxide. Each of the first metal oxide, the second metal oxide, and the third metal oxide contains at least one element selected from the group consisting of Si and Zn.
[0067] According to this embodiment, in a capacitor (1) having a first electrode (31), a second electrode (32), and a dielectric layer (2) interposed between the first electrode (31) and the second electrode (32), it is possible to achieve a high dielectric constant for the dielectric layer (2).
[0068] In the second embodiment, the dielectric layer (2) of the first embodiment comprises first particles (21) containing a first metal oxide, and the first particles (21) are dispersed in a matrix phase (23).
[0069] According to this embodiment, the relative dielectric constant of the dielectric layer (2) is increased, and the dielectric breakdown of the dielectric layer (2) is less likely to occur.
[0070] In the third embodiment, in the first or second embodiment, the dielectric layer (2) comprises second particles (22) containing a second metal oxide, and the second particles (22) are dispersed in a matrix phase (23).
[0071] According to this embodiment, the relative dielectric constant of the dielectric layer (2) is increased, and the dielectric breakdown of the dielectric layer (2) is less likely to occur.
[0072] In a fourth aspect, in any one of the first to third aspects, the first metal oxide is ZnO.
[0073] According to this embodiment, the relative dielectric constant of the dielectric layer 2 can be further increased.
[0074] In a fifth aspect, in any one of the first to fourth aspects, the second metal oxide is Zn2SiO4.
[0075] According to this embodiment, the relative dielectric constant of the dielectric layer (2) can be further increased.
[0076] In a sixth aspect, in any one of the first to fifth aspects, the third metal oxide is SiO2.
[0077] In a seventh embodiment, in any one of the first to sixth embodiments, the matrix phase (23) is amorphous.
[0078] According to this embodiment, the relative dielectric constant of the dielectric layer (2) is increased, and the dielectric breakdown of the dielectric layer (2) is less likely to occur.
[0079] In an eighth aspect, in any one of the first to seventh aspects, the ratio of Zn atoms to the total of Zn atoms and Si atoms in the dielectric layer (2) is 20 atomic % or more and 67.5 atomic % or less.
[0080] According to this embodiment, the relative dielectric constant of the dielectric layer (2) is increased, and the dielectric breakdown of the dielectric layer (2) is less likely to occur.
[0081] In a ninth aspect, in any one of the first to eighth aspects, the first electrode (31) contains aluminum, and the second electrode (32) contains a conductive polymer.
[0082] In a tenth aspect of the present invention, there is provided a method for manufacturing a capacitor (1), wherein the capacitor (1) comprises a first electrode (31), a second electrode (32), and a dielectric layer (2) interposed between the first electrode (31) and the second electrode (32). The method for manufacturing the capacitor (1) includes forming the dielectric layer (2) by a sputtering method using a target made of a mixture containing SiO2 and ZnO. The ratio of Zn atoms to the total of Zn atoms and Si atoms in the target is 20 atomic % or more and 67.5 atomic % or less.
[0083] According to this embodiment, in a capacitor (1) having a first electrode (31), a second electrode (32), and a dielectric layer (2) interposed between the first electrode (31) and the second electrode (32), it is possible to achieve a high dielectric constant for the dielectric layer (2). [Explanation of symbols]
[0084] 1 capacitor 2. Dielectric Layer 21 1st particle 22 2nd particle 23 Matrix Phase 31 1st electrode 32 2nd electrode
Claims
1. A first electrode; A second electrode; a dielectric layer interposed between the first electrode and the second electrode, the dielectric layer contains a first metal oxide, a second metal oxide, and a third metal oxide; the dielectric layer comprises a matrix phase containing the third metal oxide, the first metal oxide and the second metal oxide being dispersed in the matrix phase; the electrical conductivity of the second metal oxide is lower than the electrical conductivity of the first metal oxide, and the electrical conductivity of the third metal oxide is lower than the electrical conductivity of the second metal oxide; each of the first metal oxide, the second metal oxide, and the third metal oxide contains at least one element selected from the group consisting of Si and Zn; Capacitor.
2. the dielectric layer comprises first particles containing the first metal oxide, the first particles being dispersed in the matrix phase; The capacitor of claim 1 .
3. the dielectric layer comprises second particles containing the second metal oxide, the second particles being dispersed in the matrix phase; The capacitor of claim 1 .
4. the first metal oxide is ZnO; The capacitor of claim 1 .
5. The second metal oxide is Zn ２ SiO ４ That is, The capacitor of claim 1 .
6. The third metal oxide is SiO ２ That is, The capacitor of claim 1 .
7. The matrix phase is amorphous. The capacitor according to claim 1 or 6.
8. a ratio of Zn atoms to the total of Zn atoms and Si atoms in the dielectric layer is 20 atomic % or more and 67.5 atomic % or less; The capacitor of claim 1 .
9. the first electrode comprises aluminum; the second electrode includes a conductive polymer; The capacitor of claim 1 .
10. A method for manufacturing a capacitor, the capacitor comprises a first electrode, a second electrode, and a dielectric layer interposed between the first electrode and the second electrode; The manufacturing method includes forming the dielectric layer using SiO ２ and ZnO by a sputtering method, a ratio of Zn atoms to the total of Zn atoms and Si atoms in the target is 20 atomic % or more and 67.5 atomic % or less; How to manufacture a capacitor.
Citation Information
Patent Citations
Oxide insulator film, electronic device and method for producing electronic device
WO2022054697A1