Capacitor and method for manufacturing the same

Abstract

The present invention realizes a capacitor which uses a plurality of fiber-like conductive members, and in which the number of occurrences of short paths is reduced without substantially diminishing capacitance density. Provided is a capacitor including a conductive substrate, a plurality of fiber-like conductive members disposed on the substrate and electrically connected to the substrate, a dielectric layer covering the surfaces of the plurality of fiber-like conductive members, and a conductive layer covering the surface of the dielectric layer. Each among the plurality of fiber-like conductive members is constituted by a proximal half which is present near the surface of the substrate and a distal half which is present far from the surface of the substrate. Either the proximal halves or the distal halves have a greater number density of the plurality of fiber-like conductive members and a thicker dielectric layer than the other halves.

Description

[Technical field]

[0001] The present disclosure relates to capacitors, and more particularly to capacitors having a conductor-dielectric-conductor structure, and to methods for manufacturing such capacitors. [Background technology]

[0002] It has been known that a capacitor can be manufactured by using a fibrous member. For example, Patent Document 1 describes a method for forming a capacitor having a metal-insulator-metal (MIM) structure by forming nanofibers on a substrate (base surface) and sequentially forming a lower plate (metal), an insulating layer, and an upper plate (metal) on the surface of the nanofibers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2010-506391 [Non-patent literature]

[0004] [Non-Patent Document 1] Mostafa Bedewy, et al., "Population Growth Dynamics of Carbon Nanotubes", ACS Nano, 2011, Volume 5, Issue 11, pp. 8974-8989 [Non-Patent Document 2] Nicholas T. Dee, et al., "Carbon-assisted catalyst pretreatment enables straightforward synthesis of high-density carbon nanotube forests", Carbon, 2019, Volume 153, pp. 196-205 Summary of the Invention [Problem to be solved by the invention]

[0005] If the fibrous member is conductive, a dielectric layer can be formed on the surface of the fibrous conductive member (directly or via a conductive layer) and then a conductive layer can be formed to form a capacitor having a conductor-dielectric-conductor structure.

[0006] As the plurality of fibrous conductive members, for example, vertically aligned carbon nanotubes (hereinafter, also referred to as "VACNTs") can be used. VACNTs can be obtained by growing them at a high density on a synthesis substrate to which a catalyst is attached. The VACNTs obtained in this manner are also called "CNT forests", and it has been found that not all CNTs extend uniformly in the vertical direction from the synthesis substrate, and the number density of CNTs varies depending on the distance from the surface of the synthesis substrate. More specifically, Non-Patent Document 1 reports that, with respect to the position from the tip (free end) of the VACNT (CNT forest) to the surface of the synthesis substrate (the fixed end of the VACNT), the number density of CNTs is small at the tip of the VACNT, then increases rapidly, becomes maximum at a position at a distance of about 75% of the total length of the VACNT from the surface of the synthesis substrate, and then decreases approximately linearly from there to the surface of the synthesis substrate. Furthermore, non-patent document 2 reports that, relative to the position from the tip (free end) of the VACNT (CNT forest) to the surface of the synthetic substrate (the fixed end of the VACNT), the number density of CNTs is high (maximum) at the tip of the VACNT and decreases from there toward the surface of the synthetic substrate.

[0007] In this way, when a capacitor having a conductor-dielectric-conductor structure is manufactured by forming a dielectric layer and a conductor layer on the surface of a CNT using VACNTs whose number density varies depending on the distance from the surface of a synthetic substrate, many parts of the CNTs exposed from the dielectric layer may remain in the part where the number density of the CNTs is high, and when the capacitor is operated, a problem is considered that many short paths may occur according to the number of exposed parts (more details will be described later with reference to FIG. 12). In order to reduce the number of exposed parts, it is conceivable to simply increase the thickness of the dielectric layer. However, simply increasing the thickness of the dielectric layer leads to another problem that the capacitance density of the capacitor decreases.

[0008] The above problems are not limited to VACNTs, but can occur in common with capacitors in which the number density of fibrous conductive members in the entire set of fibrous conductive members varies depending on the distance from the surface of the substrate.

[0009] An object of the present disclosure is to realize a capacitor using a plurality of fibrous conductive members, in which the number of occurrences of short paths is reduced without substantially reducing capacitance density. [Means for solving the problem]

[0010] According to one aspect of the present disclosure, A conductive substrate; a plurality of fibrous conductive members disposed on the substrate and electrically connected to the substrate; a dielectric layer covering the surfaces of the plurality of fibrous conductive members; a conductive layer covering a surface of the dielectric layer; The capacitor includes a proximal half that is proximal to a surface of the substrate and a distal half that is distal to the surface of the substrate, and one of the proximal half and the distal half has a higher number density of the fibrous conductive members and a larger thickness of the dielectric layer than the other of the proximal half and the distal half.

[0011] According to another aspect of the present disclosure, (a) preparing a plurality of fibrous conductive members disposed on a first substrate and directly bonded to the first substrate at one end, the plurality of fibrous conductive members being composed of a fixed end half located proximal to a surface of the first substrate and a free end half located distal to the surface of the first substrate, the free end half having a higher number density of the plurality of fibrous conductive members than the fixed end half; (b) forming a dielectric layer covering the surfaces of the plurality of fibrous conductive members by a liquid phase deposition method or a sputtering method, the thickness of the dielectric layer being greater in the free end half than in the fixed end half; and (c) forming a conductive layer covering the surface of the dielectric layer; A method for manufacturing a capacitor is provided, including: Effect of the Invention

[0012] According to the present disclosure, in a capacitor using a plurality of fibrous conductive members, when the plurality of fibrous conductive members are divided into a proximal half located proximal to a surface of a substrate and a distal half located distal to the surface of the substrate, one of the two halves has a higher numerical density of the plurality of fibrous conductive members and a larger thickness of the dielectric layer than the other, thereby realizing a capacitor in which the number of occurrences of short paths is reduced without substantially reducing capacitance density. [Brief description of the drawings]

[0013] [Figure 1A] 1 shows a schematic cross-sectional view of a capacitor according to a first embodiment of the present disclosure. [Figure 1B] This shows a diagram in which the dielectric layer and the conductive layer are omitted from FIG. 1A. [Figure 2A] 1 shows a schematic cross-sectional view of a capacitor according to a second embodiment of the present disclosure. [Figure 2B]This shows a diagram in which the dielectric layer and the conductive layer are omitted from FIG. 2A. [Figure 3A] FIG. 13 shows a schematic cross-sectional view of a capacitor according to a third embodiment of the present disclosure. [Figure 3B] This shows a diagram in which the dielectric layers and conductive layers are omitted from FIG. 3A. [Figure 4] FIG. 13 shows a schematic cross-sectional view of a capacitor according to a first modified example of the second embodiment of the present disclosure. [Diagram 5] FIG. 2 shows a schematic cross-sectional view of a capacitor according to a first modified example of the first embodiment of the present disclosure. [Figure 6] FIG. 13 shows a schematic cross-sectional view of a capacitor in a second modified example of the second embodiment of the present disclosure. [Figure 7] FIG. 13 shows a schematic cross-sectional view of a capacitor according to a third modified example of the second embodiment of the present disclosure. [Figure 8] FIG. 13 shows a schematic cross-sectional view of a capacitor according to a first modified example of the third embodiment of the present disclosure. [Figure 9] 1 shows an SEM image of a parallel cross section of the sample produced in Example 1 embedded in resin. [Figure 10A] 1 shows an SEM image of a vertical cross section of the sample produced in Example 1 embedded in resin. [Figure 10B] FIG. 10B is an enlarged view of part A in FIG. 10A. [Figure 11] 1 shows an SEM image of a parallel cross section of the sample produced in Comparative Example 1 embedded in resin. [Figure 12A] FIG. 2 shows a schematic cross-sectional view of a capacitor described herein for comparative purposes to the present disclosure. [Figure 12B] This shows a diagram in which the dielectric layer and the conductive layer are omitted from FIG. 12A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Capacitors according to three embodiments of the present disclosure will be described in detail below with reference to the drawings, but the present disclosure is not limited to these embodiments.

[0015] (Embodiment 1) This embodiment relates to an embodiment in which the number density of fibrous conductive members in a plurality of fibrous conductive members is higher in the distal half relative to the surface of the substrate than in the proximal half, and no adhesive layer is present (Figures 1A and 1B).

[0016] Referring to FIG. 1A, a capacitor 20A according to the present embodiment has: A conductive substrate 1; A plurality of fibrous conductive members 3 disposed on the substrate 1 and electrically connected to the substrate 1; A dielectric layer 7 that covers the surfaces of the plurality of fibrous conductive members 3; A conductive layer 9 covering the surface of the dielectric layer 7; Includes.

[0017] The multiple fibrous conductive members 3 are conductive (typically conductors) and can be at the same potential or voltage as one another by being electrically connected to the substrate 1. Thus, a conductor-dielectric-conductor structure is formed by the fibrous conductive members 3, the dielectric layer 7 and the conductor layer 9. Such a conductor-dielectric-conductor structure can be understood as corresponding to a so-called MIM structure (metal-insulator-metal structure). A capacitor 20A having such a structure can obtain a high capacitance density due to the large specific surface area of ​​the fibrous conductive members 3.

[0018] 1B is a diagram in which the dielectric layer 7 and the conductor layer 9 are omitted for the sake of convenience in order to better understand the capacitor 20A of this embodiment. When the plurality of fibrous conductive members 3 are understood as being virtually divided into two, they can be understood to be composed of a proximal half 3p located proximal to the surface 1a of the substrate 1 and a distal half 3d located distal to the surface 1a of the substrate 1.

[0019] 1A and 1B, M denotes an imaginary dividing line. M may be at a distance from the surface 1a of the substrate 1 that is 50% of the length L of the plurality of fibrous conductive members 3. In the present disclosure, the length L of the plurality of fibrous conductive members 3 is defined as the maximum length of the plurality of fibrous conductive members 3 from the surface 1a of the substrate 1.

[0020] In the present disclosure, one of the proximal half 3p and the distal half 3d has a higher number density (d) of the multiple fibrous conductive members 3 and a larger thickness (t) of the dielectric layer 7 than the other half. In other words, the half on the side where the number density of the multiple fibrous conductive members 3 is relatively high (the one half) has a thicker dielectric layer 7 covering the surfaces of the multiple fibrous conductive members 3 than the half on the side where the number density of the multiple fibrous conductive members 3 is relatively low (the other half).

[0021] More specifically, in this embodiment, the one is the distal half 3d, and the other is the proximal half 3p. That is, in this embodiment, the distal half 3d has a higher number density (d) of the plurality of fibrous conductive members 3 and a larger thickness (t) of the dielectric layer 7 than the proximal half 3p. In other words, the distal half 3d, in which the number density of the plurality of fibrous conductive members 3 is relatively high, has a larger thickness of the dielectric layer 7 covering the surfaces of the plurality of fibrous conductive members 3 than the proximal half 3p, in which the number density of the plurality of fibrous conductive members 3 is relatively low.

[0022] Due to such a feature of the present disclosure, in the half on the side where the number density of the plurality of fibrous conductive members 3 is relatively high (the distal half 3d in this embodiment), the thickness of the dielectric layer 7 can be made relatively large, effectively reducing, preferably substantially eliminating, the number of locations where the plurality of fibrous conductive members 3 are exposed from the dielectric layer 7, and effectively reducing, preferably substantially eliminating, the number of short paths that occur when the capacitor 20A is operated. And, in the half on the side where the number density of the plurality of fibrous conductive members 3 is relatively low (the proximal half 3p in this embodiment), the thickness of the dielectric layer 7 can be made relatively small, preventing a substantial decrease in the capacitance density of the capacitor 20A, and a high capacitance density can be obtained.

[0023] For comparison, Fig. 12A shows a capacitor 60 in which the number density of the fibrous conductive members 63 is higher in the distal half 63d than in the proximal half 63p, but the thickness of the dielectric layer 67 is uniform in both the distal half 63d and the proximal half 63p (Fig. 12B is a view corresponding to Fig. 1B). In such a capacitor 60, there are many exposed portions of the fibrous conductive members 63 from the dielectric layer 67 (a representative portion is shown surrounded by a dotted line in Fig. 12A) in the portion with a high number density of the fibrous conductive members 63 (in the illustrated embodiment, the distal half 63d), and when the capacitor 60 is operated, there is a problem that many short paths may occur between the fibrous conductive members 63 and the conductor layer 69. Simply increasing the thickness of the dielectric layer 67 (in other words, uniformly) leads to another problem that the capacitance density of the capacitor 60 decreases.

[0024] As can be seen from the above, according to the capacitor of the present disclosure, it is possible to realize a capacitor in which the number of occurrences of short paths is reduced without substantially reducing the capacitance.

[0025] In the present disclosure, the number density (also referred to as "number density") d of the plurality of fibrous conductive members is measured as follows. First, if a space (a space corresponding to the shape of the exposed surface of the conductive layer 9 in the capacitor 20A shown in FIG. 1A and FIG. 1B) exists in the capacitor 20A, the space is filled with any suitable resin, and a cross section ("parallel cross section") parallel to the surface 1a of the substrate 1 is exposed at a predetermined distance (or position) from the surface 1a. Such a parallel cross section can be exposed by polishing. The parallel cross section thus exposed is observed with a scanning electron microscope (SEM), and the number of fibrous conductive members per unit area is calculated in one visual field of 3 μm×3 μm or more to obtain the number density in that visual field. This operation is repeated to obtain number densities in five or more visual fields, and the average value of these is taken as the number density d of the plurality of fibrous conductive members at that distance. The in-plane positions of these visual fields are not particularly limited, but are preferably selected so that they are substantially at the same position at each distance. In other words, it is preferable that the area of ​​each field of view selected in a parallel cross section at a certain distance projected onto the surface 1a of the substrate 1 is substantially the same as the area of ​​each field of view selected in a parallel cross section at another distance projected onto the surface 1a of the substrate 1.

[0026] The thickness t of the dielectric layer is measured as follows. After exposing a cross section parallel to the surface 1a of the substrate 1 at a predetermined distance from the surface 1a as described above, a cross section perpendicular to the surface 1a of the substrate 1 ("vertical cross section") is then exposed. The vertical cross section thus exposed is observed with a scanning electron microscope (SEM), and an isolated fibrous conductive member is selected in the SEM image, in which the center (ideally the center line) along the longitudinal direction of the fibrous conductive member is revealed, and the dielectric layer and conductor layer (in this embodiment, the boundary between the fibrous conductive member and the dielectric layer and the boundary between the dielectric layer and the conductor layer) covering the surface of the fibrous conductive member can be identified. The outer diameter D of the fibrous conductive member near the end opposite to the substrate 1 is measured. 1 and the outer diameter D of the dielectric layer covering the surface 2 The difference between these outer diameters is then divided by 2 ((D 2 -D1 The thickness of the dielectric layer covering the surface of the fibrous conductive member can be calculated by dividing the outer diameter D of the dielectric layer by the outer diameter D of the dielectric layer. By repeating this procedure, the thicknesses of the dielectric layers are obtained for 10 or more, preferably 20 or more, fibrous conductive members, and the average value of these is taken as the thickness t of the dielectric layer at that distance. 2 is measured only for the dielectric layer covering the surface of the fibrous conductive member. The vertical cross section may be one or more vertical cross sections taken at any suitable in-plane position.

[0027] The thickness t of the dielectric layer may be measured from a parallel cross section exposed at a predetermined distance from the surface 1a of the substrate 1. The parallel cross section is observed with an SEM, and a single fibrous conductive member is selected in which the dielectric layer and the conductor layer (in this embodiment, the boundary between the fibrous conductive member and the dielectric layer and the boundary between the dielectric layer and the conductor layer) covering the surface of the fibrous conductive member can be identified in the SEM image, and the outer diameter D of the fibrous conductive member is determined. 11 and the outer diameter D of the dielectric layer covering the surface 21 The difference between these outer diameters is then divided by 2 ((D 21 -D 11 The thickness of the dielectric layer covering the surface of the fibrous conductive member can be calculated by dividing the outer diameter D of the dielectric layer by the outer diameter D of the dielectric layer. By repeating this procedure, the thicknesses of the dielectric layers are obtained for 10 or more, preferably 20 or more, fibrous conductive members, and the average value of these is taken as the thickness t of the dielectric layer at that distance. 21 is measured only for the dielectric layer covering the surface of the fibrous conductive member.

[0028] The number density (d) of the plurality of fibrous conductive members 3 in the distal half 3d and the thickness (t) of the dielectric layer 7 may be the number density and thickness inside the distal half 3d. In one representative example, the number density (d 75 ) and thickness (t 75 ) can be applied. The number density d75 and thickness t 75 can be obtained by exposing the parallel cross section or the perpendicular cross section at a distance of 75% of the length L from the surface 1a of the substrate 1. In the present disclosure, the number density and thickness measured by setting the exposure position at the distance of 75% can be obtained without any problem even if the actual measurement position is slightly shifted (for example, within a range of 75% ± 5%). 75 and thickness t 75 In another representative example, the number density (d 90 ) and thickness (t 90 ) can be applied. The number density d 90 and thickness t 90 can be obtained by exposing the parallel cross section or the perpendicular cross section at a distance of 90% of the length L from the surface 1a of the substrate 1. In the present disclosure, the number density and thickness measured by setting the exposure position at the distance of 90% can be obtained without any problem even if the actual measurement position is slightly shifted (for example, within a range of 90% ± 5%). 90 and thickness t 90 It is acceptable to treat it as such.

[0029] The number density (d) of the plurality of fibrous conductive members 3 and the thickness (t) of the dielectric layer 7 in the proximal half 3p may be the number density and thickness inside the proximal half 3p. In one representative example, the number density (d 25 ) and thickness (t 25 ) can be applied. The number density d 25 and thickness t 25 can be obtained by exposing the parallel cross section or the perpendicular cross section at a distance of 25% of the length L from the surface 1a of the substrate 1. In the present disclosure, the number density and thickness measured by setting the exposure position at the distance of 25% can be obtained without any problem even if the actual measurement position is slightly shifted (for example, within a range of 25% ± 5%). 25 and thickness t 25In another representative example, the number density (d 10 ) and thickness (t 10 ) can be applied. The number density d 10 and thickness t 10 can be obtained by exposing the parallel cross section or the perpendicular cross section at a distance of 10% of the length L from the surface 1a of the substrate 1. In the present disclosure, the number density and thickness measured by setting the exposure position at the distance of 10% can be obtained without any problem even if the actual measurement position is slightly shifted (for example, within a range of 10% ± 5%). 10 and thickness t 10 It is acceptable to treat it as such.

[0030] Thus, in one representative example, the capacitor 20A of this embodiment has a capacitance of d 75 >d 25 And 75 >t 25 In another representative example, the capacitor 20A of the present embodiment may satisfy d 90 >d 10 And 90 >t 10 It may be something that satisfies.

[0031] The number density d of the multiple fibrous conductive members 3 may differ (change) depending on the relative distance from the surface 1a of the substrate 1 (based on the length L of the multiple fibrous conductive members 3). Although not limiting this embodiment, in one representative example, the number density d of the multiple fibrous conductive members 3 may be small at 100% relative distance from the surface 1a of the substrate 1 to 0%, then increase rapidly to a maximum at about 75%, and decrease (e.g., approximately linearly) from there to 0%. For example, d 75 >d 90 >d 25 >d 10In another representative example, the number density d of the multiple fibrous conductive members 3 may be large (may be maximum) at 100-90% (at or near the tips of the multiple fibrous conductive members 3) relative to the relative distance from the surface 1a of the substrate 1 from 100% to 0%, and may decrease (e.g., approximately linearly) from there toward 10-0% (at or near the surface 1a of the substrate 1). For example, d 90 >d 75 >d 25 >d 10 It may be.

[0032] The thickness t of the dielectric layer 7 may differ (change) depending on the relative distance from the surface 1a of the substrate 1 (based on the length L of the multiple fibrous conductive members 3). It may be considered desirable for the thickness t of the dielectric layer 7 to differ according to the number density d of the multiple fibrous conductive members 3, but this is not essential to the present disclosure, and the thickness t may differ (change) independently of the number density d. Although not limiting this embodiment, the thickness t of the dielectric layer 7 may decrease (e.g., approximately linearly) from 100% to 0% as the relative distance from the surface 1a of the substrate 1 increases from 100% to 0%. For example, t 90 >t 75 >t 25 >t 10 It may be.

[0033] Without being limiting to this embodiment, the half of the plurality of fibrous conductive members 3 on the side where the number density of the plurality of fibrous conductive members 3 is relatively high (the above-mentioned one side, the distal half 3d in this embodiment) may have more surface defects than the half on the side where the number density of the plurality of fibrous conductive members 3 is relatively low (the above-mentioned other side, the proximal half 3p in this embodiment). The more surface defects there are, the thicker the dielectric layer 7 can be formed. Thus, a thicker dielectric layer can be formed in the half on the side where the number density of the plurality of fibrous conductive members 3 is relatively high. This point will be described in detail in the explanation of the manufacturing method of the capacitor 20A.

[0034] In the present disclosure, the fiber-shaped conductive member 3 (each of the multiple fiber-shaped conductive members 3) is not particularly limited as long as its longitudinal dimension (length) is larger (preferably significantly larger) than the maximum cross-sectional dimension perpendicular to the longitudinal direction and is roughly in the form of a long, thin thread.

[0035] The longer the length of the fibrous conductive member 3, the greater the capacity density per area, and therefore the more preferable it is. The length of the fibrous conductive member 3 can be, for example, several μm or more, 20 μm or more, 50 μm or more, 100 μm or more, 500 μm or more, 750 μm or more, 1000 μm or more, or 2000 μm or more. The upper limit of the length of the fibrous conductive member 3 can be appropriately selected, but the length of the fibrous conductive member 3 can be, for example, 10 mm or less, 5 mm or less, or 3 mm or less.

[0036] The maximum cross-sectional dimension of the fibrous conductive member 3 may be, for example, 0.1 nm or more, 1 nm or more, or 10 nm or more. The maximum cross-sectional dimension of the fibrous conductive member 3 may be, for example, 1 nm or more, or 10 nm or more. The maximum cross-sectional dimension of the fibrous conductive member 3 may be less than 1000 nm, 800 nm or less, or 600 nm or less.

[0037] The smaller the distance between adjacent fibrous conductive members 3, the greater the capacity density per area, which is preferable. The distance between adjacent fibrous conductive members 3 may be, for example, 10 nm or more and 1 μm or less. However, the present disclosure is not limited thereto, and adjacent fibrous conductive members 3 may be in partial contact with each other.

[0038] The fibrous conductive member 3 is preferably a conductive nanofiber (having a maximum cross-sectional dimension on the nanoscale (1 nm or more and less than 1000 nm)). The conductive nanofiber may be, for example, a conductive nanotube (hollow, preferably cylindrical) or a conductive nanorod (solid, preferably cylindrical). A nanorod having electrical conductivity (including semiconductivity) is also called a nanowire.

[0039] Conductive nanofibers that can be used in the present disclosure include, but are not limited to, carbon nanofibers, etc. Conductive nanotubes that can be used in the present disclosure include, but are not limited to, metal nanotubes, organic conductive nanotubes, inorganic conductive nanotubes, etc. Typically, the conductive nanotubes can be carbon nanotubes or titania carbon nanotubes. Conductive nanorods (nanowires) that can be used in the present disclosure include, but are not limited to, silicon nanowires, silver nanowires, etc.

[0040] Preferably, the fibrous conductive member 3 is a carbon nanotube. Carbon nanotubes have electrical and thermal conductivity. Carbon nanotubes have high strength and flexibility, and tend to maintain a vertically oriented state.

[0041] The chirality of the carbon nanotubes is not particularly limited, and may be either a semiconducting type or a metallic type, or may be a mixture of these. From the viewpoint of reducing the resistance value, a higher ratio of metallic types is preferable.

[0042] The number of walls of the carbon nanotube is not particularly limited, and it may be either a single-walled SWCNT (single-walled carbon nanotube) with one wall or a multi-walled carbon nanotube (MWCNT) with two or more walls.

[0043] The plurality of fibrous conductive members 3 may be so-called vertically aligned carbon nanotubes (VACNTs). VACNTs have a large specific surface area and have the advantage that they can be grown and manufactured in a vertically aligned state on a synthesis substrate, as described below. Although they are called VACNTs, in reality, not all CNTs extend uniformly in the vertical direction from the synthesis substrate, and the number density of CNTs may vary depending on the distance from the surface of the synthesis substrate. This point will be described in detail in the description of the manufacturing method of the capacitor 20A.

[0044] The substrate 1 has two mutually opposing main surfaces 1a (front surface) and 1b (rear surface), and may be in the form of, for example, a plate (substrate), a foil, a film, a block, or the like.

[0045] The material constituting the substrate 1 can be appropriately selected as long as it is conductive and can be electrically connected to the plurality of fibrous conductive members 3. For example, it can be a semiconductor material such as silicon, a conductive material such as metal (copper, aluminum, nickel), or an insulating (or relatively low conductive) material such as ceramic (silicon oxide) or resin. The substrate 1 can be made of a single material, a mixture of two or more materials, or a composite composed of two or more materials. It is preferable that the material constituting the substrate 1 is a metal, since it is easily usable as a contact with the outside, can have a low resistance value, and can withstand high temperatures.

[0046] The thickness of the substrate 1 is not particularly limited and may vary depending on the application of the capacitor 20 A. The substrate 1 may be provided with electrodes for contacting the outside and wiring for ensuring electrical conduction.

[0047] 1A, in the capacitor 20A of this embodiment, a plurality of fibrous conductive members 3 may be directly bonded to the substrate 1 without an adhesive layer (more specifically, the fibrous conductive members 3 and the substrate 1 are bonded through direct contact with each other, and more specifically, are directly synthesized as described below). Since there is no adhesive layer, the height of the capacitor 20A can be reduced by the thickness of the adhesive layer.

[0048] As shown in FIG. 1A, the dielectric layer 7 may entirely cover the surfaces of the multiple fibrous conductive members 3 (excluding the areas directly bonded to the substrate 1) as well as the surface 1a of the substrate 1 (excluding the areas bonded to the multiple fibrous conductive members 3).

[0049] The dielectric material constituting the dielectric layer 7 may be appropriately selected, and examples thereof include silicon dioxide, aluminum oxide, silicon nitride, tantalum oxide, hafnium oxide, barium titanate, lead zirconate titanate, etc. These may be used alone or in combination of two or more kinds (for example, laminated).

[0050] The thickness t of the dielectric layer 7 is preferably 5 nm or more, and more preferably 10 nm or more. By making the thickness of the dielectric layer 7 5 nm or more, it is possible to increase the insulation property and reduce the leakage current. The thickness t of the dielectric layer 7 may be, for example, 1 μm or less, preferably 100 nm or less, and more preferably 50 nm or less. By making the thickness t of the dielectric layer 7 1 μm or less, it is possible to obtain a larger electrostatic capacitance.

[0051] The conductive material constituting the conductor layer 9 is not particularly limited, and may be, for example, a metal, a conductive polymer (a polymer material having conductivity and / or having conductivity imparted thereto, also referred to as an organic conductive material), or the like. These may be used alone or in combination of two or more. Examples of the metal include silver, gold, copper, platinum, aluminum, or an alloy containing at least two of these. Examples of the conductive polymer include PEDOT (polyethylenedioxythiophene), PPy (polypyrrole), PANI (polyaniline), and the like, which may be doped with a dopant such as an organic sulfonic acid compound, for example, polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylsulfonic acid, polymethacrylsulfonic acid, poly-2-acrylamido-2-methylpropanesulfonic acid, or polyisoprenesulfonic acid, as appropriate. The conductor layer 9 may be a laminate of multiple layers of different conductive materials.

[0052] The thickness of the conductive layer 9 may be, for example, 3 nm or more, preferably 10 nm or more. By making the thickness of the conductive layer 9 3 nm or more, the resistance value of the conductive layer 9 itself can be reduced. The thickness of the conductive layer 9 may be, for example, 500 nm or less, particularly 100 nm or less. In this embodiment, the conductive layer 9 may be provided with voids (or trench structures) corresponding to the spaces between the multiple fibrous conductive members 3 as shown in the figure. However, the thickness of the conductive layer 9 may be greater, and for example, the voids (trench structures) may be eliminated.

[0053] The capacitor 20A of this embodiment can be obtained by a manufacturing method including, for example, the following: (a) preparing a plurality of fibrous conductive members 3 disposed on a first substrate and directly bonded to the first substrate at one end (more specifically, fixed by direct synthesis as described below), the plurality of fibrous conductive members 3 being composed of a fixed end half located proximal to the surface of the first substrate and a free end half located distal to the surface of the first substrate, the free end half having a higher number density (d) of the plurality of fibrous conductive members 3 than the fixed end half; (b) forming a dielectric layer 7 that covers the surfaces of the plurality of fibrous conductive members 3 by a liquid phase deposition method or a sputtering method, the thickness (t) of the dielectric layer 7 being greater in the free end half than in the fixed end half; and (c) forming a conductive layer 9 covering the surface of the dielectric layer 7;

[0054] In this embodiment, the first substrate is the same as the substrate 1 in the capacitor 20A. In addition, in this embodiment, the fixed end half and the free end half of the multiple fibrous conductive members 3 correspond to the proximal half 3p and the distal half 3d, respectively, in the capacitor 20A.

[0055] Steps (a) to (c) are described in more detail below. Note that, although an exemplary case where the fibrous conductive member 3 is VACNT is described below, in this embodiment, the fibrous conductive member 3 is not limited to VACNT, and the capacitor 20A may be manufactured using any appropriate method depending on the fibrous conductive member 3 used. Furthermore, unless otherwise specified, the above description of this embodiment may also apply to the manufacturing method described below.

[0056] ·Process (a) First, a plurality of fibrous conductive members 3 are prepared, which are disposed on a first substrate and directly bonded to the first substrate at one end.

[0057] Step (a) can be carried out by applying a catalyst onto a first substrate and growing a plurality of fibrous conductive members 3 from the first substrate (in other words, directly synthesizing them on the first substrate). More specifically, the process is as follows.

[0058] The first substrate may be a synthetic substrate for growing VACNTs as the fibrous conductive member 3. In general, the material of the synthetic substrate is not particularly limited, and for example, silicon oxide, silicon, gallium arsenide, aluminum, SUS, etc. can be used. In this embodiment, a substrate 1 having conductivity is used as the first substrate (synthetic substrate).

[0059] First, a catalyst is attached onto a first substrate (synthetic substrate). The catalyst may be iron, nickel, platinum, cobalt, or an alloy containing these metals. Chemical vapor deposition (CVD), sputtering, physical vapor deposition (PVD), atomic layer deposition (ALD), or the like may be used to attach the catalyst to the synthetic substrate, and such techniques may be combined with techniques such as lithography and etching in some cases.

[0060] Then, VACNTs are grown (synthesized directly) on the synthesis substrate to which the catalyst is attached. The method for growing VACNTs is not particularly limited, and CVD, plasma-enhanced CVD, or the like can be used under heating as necessary. The gas used is not particularly limited, and for example, at least one selected from the group consisting of carbon monoxide, methane, ethylene, and acetylene, or a mixture of at least one of these with hydrogen and / or ammonia, or the like can be used. If desired, moisture may be present in the ambient atmosphere during the growth of VACNTs. As a result, VACNTs grow on the synthesis substrate with the catalyst as a nucleus. The end of the VACNT on the side of the synthesis substrate to which the catalyst is attached is the fixed end that is fixed to the synthesis substrate (generally via the catalyst), and the opposite end of the VACNT is the free end that is the growth point. The length and diameter of the VACNTs can vary depending on parameters such as gas concentration, gas flow rate, and temperature. That is, the length and diameter of the VACNTs can be adjusted by appropriately selecting these parameters.

[0061] As a result, VACNTs (CNT forests) are produced on the synthesis substrate. Strictly speaking, the length of each CNT in the obtained VACNT may vary (for example, in-plane variation) on the free end side due to differences in growth rate, etc., and the maximum length of these is defined as the length L of the VACNT. The number density (d) of CNTs in the obtained VACNTs will differ from 100% to 0% of the relative distance (based on the length L of the VACNT) from the surface of the synthesis substrate. In one representative example, the number density (d) is small at the relative distance of 100%, then increases rapidly and becomes maximum at about 75%, and can decrease (for example, approximately linearly) from there to 0% (Non-Patent Document 1). In another representative example, the number density d is large (may be maximum) at the relative distance of 100 to 90%, and can decrease (for example, approximately linearly) from there to 10 to 0% (Non-Patent Document 2).

[0062] When VACNTs are grown on a synthesis substrate with a catalyst attached, the catalyst becomes inactive during the synthesis of VACNTs, and some CNTs stop growing. The CNTs whose growth has stopped become entangled with the continuing growing CNTs and are pulled, so that their fixed ends are detached from the synthesis substrate and pulled up toward the tip of the VACNTs. As a result, it is thought that the number density (d) of the CNTs in the obtained VACNTs varies depending on the distance (relative distance) from the surface of the synthesis substrate, as described above.

[0063] The VACNTs (multiple fibrous conductive members 3) obtained as described above are placed on a first substrate (synthetic substrate) and are directly bonded to the first substrate at one end (however, as will be understood from the above explanation, some CNTs among the VACNTs do not need to be directly bonded to the first substrate). If such a VACNT is understood as being virtually divided into two, it can be understood to be composed of a fixed end half that is proximal to the surface of the first substrate, and a free end half that is distal to the surface of the first substrate. The number density (d) of the CNTs in such a VACNT is higher in the free end half than in the fixed end half.

[0064] ·Process (b) Next, the dielectric layer 7 that covers the surfaces of the VACNTs (the plurality of fibrous conductive members 3) is formed by liquid phase film formation or sputtering.

[0065] The liquid phase film formation method may be, for example, a sol-gel method, plating, etc. When the dielectric layer 7 is made of a metal oxide, a method in which plating and surface oxidation treatment are combined may be used.

[0066] By appropriately selecting or setting the conditions for carrying out the liquid phase film deposition method, the thickness (t) of the formed dielectric layer 7 can be made to differ depending on the distance from the surface of the first substrate, and the thickness (t) of the dielectric layer 7 can be made greater in the half on the free end side than in the half on the fixed end side. The liquid phase film deposition method makes it easy to adjust the generation of a substance that serves as the nucleus of the reaction that forms the film and the degree of penetration of the substance between the CNTs (for example, it is possible to adsorb more of the substance on the surface on the free end side of the CNTs and reduce the amount that penetrates toward the fixed end).

[0067] Although this embodiment is not limited thereto, for example, the composition of the liquid used in the liquid phase film formation method, the solvent used for the preparation (e.g., water, ethanol, isopropanol), the film formation time, the stirring speed, the temperature, and the like are appropriately selected or set.

[0068] However, as long as the thickness (t) of the dielectric layer 7 can be made larger in the free end half than in the fixed end half, the method of depositing the dielectric layer 7 is not necessarily limited to the liquid phase deposition method. For example, a sputtering method, which is one of the vapor phase deposition methods, may be applied. More specifically, in order to change the thickness of the dielectric layer 7 by the sputtering method, it is sufficient to appropriately select a material (raw material) and appropriately select or set the implementation conditions of the positional relationship (distance, angle) between the material substrate and the material to be deposited.

[0069] In addition, although not essential to this embodiment, a treatment for introducing surface defects into the VACNTs may be performed after step (a) and before step (b). The treatment for introducing surface defects may be an acid treatment, a heat treatment, a UV treatment, or the like.

[0070] By appropriately selecting or setting the conditions for the process of introducing surface defects, the number of surface defects introduced can be made to vary depending on the distance from the surface of the first substrate, so that the number of surface defects is greater in the free end half than in the fixed end half.

[0071] The more surface defects there are, the thicker the dielectric layer 7 can be formed. Therefore, a thicker dielectric layer can be formed in the half on the free end side where the number density of VACNTs is relatively high.

[0072] The surface defects of CNTs can be evaluated based on the G / D ratio obtained using Raman spectroscopy. The G / D ratio is determined by the G band (1590 cm , which originates from the in-plane vibration of the six-membered ring common to carbon-based materials). -1 The peak near 1350 cm -1 The G / D ratio is the ratio of the surface defects to the peak near the surface of the CNT, and is used as an index of the amount of defects in the CNT. The smaller the G / D ratio, the more surface defects there are. The surface defects may be surface functional groups such as hydroxyl groups or carboxyl groups. The functional groups present on the surface of the CNT can be quantitatively evaluated using X-ray photoelectron spectroscopy (XPS) and other methods.

[0073] ·Process (c) Thereafter, a conductive layer 9 is formed to cover the surface of the dielectric layer 7.

[0074] The method for forming the conductive layer 9 is not particularly limited, and may be a liquid phase deposition method, a vapor phase deposition method, or a combination thereof. The liquid phase deposition method may be, for example, a sol-gel method, plating, etc. The vapor phase deposition method may be, for example, ALD, sputtering, CVD, etc.

[0075] For example, the conductor layer 9 can be formed by a liquid phase film formation method using a conductive polymer. More specifically, the conductor layer 9 can be formed by applying / supplying (e.g., coating or immersion) a liquid composition in which a conductive polymer is dissolved or dispersed in an organic solvent to a predetermined surface / portion. The conductive polymer can easily penetrate into the space formed between the multiple fibrous conductive members 3 covered with the dielectric layer 7, and the conductor layer 9 can be appropriately formed even in the deep part of the space (e.g., the bottom part).

[0076] As a result of the above, referring again to FIG. 1A, a capacitor 20A can be manufactured, which has a plurality of fibrous conductive members 3 (VACNTs) arranged on a conductive first substrate (which is the same as substrate 1 in this embodiment) and electrically connected to the first substrate, a dielectric layer 7, and a conductor layer 9.

[0077] In this embodiment, the substrate 1 included in the capacitor 20A is the same as the first substrate used to fabricate the capacitor 20A, and is a synthetic substrate. It is possible to determine whether the substrate 1 is a synthetic substrate by detecting a catalyst. If the substrate 1 included in the capacitor is analyzed and a catalyst is detected on the surface of the substrate 1, the substrate 1 may be considered to be a synthetic substrate.

[0078] (Embodiment 2) This embodiment relates to an embodiment in which the number density of the fibrous conductive members in the plurality of fibrous conductive members is higher in the distal half of the substrate than in the proximal half, and an adhesive layer is present (FIGS. 2A and 2B). Unless otherwise specified in this embodiment, the explanation in embodiment 1 may also apply to this embodiment (the same applies to the following embodiments and modified examples).

[0079] 2A, in a capacitor 21A of this embodiment, a plurality of fibrous conductive members 3 are bonded to a substrate 1 via an adhesive layer 11.

[0080] In this embodiment, the dielectric layer 7 may entirely cover the surfaces of the multiple fibrous conductive members 3 (excluding the areas directly bonded to the substrate 1 and the areas embedded in the adhesive layer 11) as well as the surface 11a of the adhesive layer 11 (excluding the areas bonded to the multiple fibrous conductive members 3), as shown in FIG. 2A.

[0081] In this embodiment, the adhesive layer 11 may or may not be conductive. When the adhesive layer 11 is conductive, the plurality of fibrous conductive members 3 can be reliably set to the same potential or voltage via the adhesive layer 11, and can be reliably electrically connected to the substrate 1.

[0082] The capacitor 21A of this embodiment may be manufactured by any suitable method, including, but not limited to, the following first and second manufacturing examples.

[0083] In a first manufacturing example, in the manufacturing method of the capacitor 20A described above in embodiment 1, after step (a) and before step (b), a hardenable (or flowable, the same applies below) material may be supplied (e.g., poured) onto the surface 1a of the substrate 1 (excluding the area bonded to the plurality of fibrous conductive members 3) and hardened (or made non-flowable, the same applies below) to form the adhesive layer 11. When a process for introducing surface defects into the plurality of fibrous conductive members 3 (VACNT) is performed, such a process may be performed either before or after the adhesive layer 11 is formed. Thereafter, the capacitor 21A can be obtained in the same manner as in embodiment 1.

[0084] In the first manufacturing example, the substrate 1 included in the capacitor 21A is the same as the first substrate used to fabricate the capacitor 21A, and is a synthetic substrate. As described in the first embodiment, it is possible to determine whether the substrate 1 is a synthetic substrate by detecting a catalyst. If the substrate 1 included in the capacitor is analyzed and a catalyst is detected on the surface of the substrate 1, the substrate 1 may be considered to be a synthetic substrate.

[0085] The adhesive layer 11 that can be used in the first manufacturing example may be, for example, a cured (or non-fluidized) product of any suitable curable (or flowable) material (for example, a so-called adhesive). The curable (or flowable) material may be a curable material, for example, a material that can be cured by heat, light, radiation, moisture, etc., and is preferably a thermosetting material. Alternatively, the curable (or flowable) material may be a thermoplastic material, and the adhesive layer 11 may be formed by plasticizing / fluidizing the thermoplastic material in advance by heating, supplying (for example, pouring) the thermoplastic material onto the surface 1a of the substrate 1 (except for the area bonded to the plurality of fibrous conductive members 3), and then losing its fluidity by dissipating heat. The curable material may be a known adhesive or adhesive paste, and may or may not contain a conductive filler.

[0086] Examples of the conductive curable material include a conductive filler dispersed in any suitable curable resin / polymer, a conductive and curable resin / polymer, etc. Examples of the former include a material in which a metal filler such as gold, silver, nickel, copper, tin, or palladium, or a carbon filler is dispersed in a resin such as an epoxy resin, a polyimide resin, a silicone resin, or a polyurethane resin. Examples of the latter include polypyrrole, a polypyrrole derivative, polyaniline, a polyaniline derivative, polythiophene, a polythiophene derivative, etc.

[0087] The hardenable material may be in a paste, sheet, gel, or liquid form. In order to facilitate pouring the hardenable material into the gaps between the plurality of fibrous conductive members 3, a liquid or gel hardenable material, or a thermosetting or thermoplastic material whose viscosity is temporarily reduced when heated and which can become liquid or gel is preferred.

[0088] In the second manufacturing example, in the manufacturing method of the capacitor 20A described above in the first embodiment, after step (a) and before step (b), the plurality of fibrous conductive members 3 on the first substrate may be transferred onto any suitable support substrate, the first substrate may be removed, and the plurality of fibrous conductive members 3 may be transferred onto a separately prepared substrate 1 having an adhesive layer 11 on its surface 1a, and the support substrate may be removed. When a process for introducing surface defects into the plurality of fibrous conductive members 3 (VACNT) is performed, such a process may be performed at any suitable timing. Thereafter, the capacitor 21A can be obtained in the same manner as in the first embodiment.

[0089] In the second manufacturing example, the substrate 1 included in the capacitor 21A is different from the first substrate used to fabricate the capacitor 21A. Thus, in the second manufacturing example, the first substrate does not need to be conductive, and any appropriate substrate may be used. In the second manufacturing example, the substrate 1 included in the capacitor 21A is not the first substrate, and is therefore not a synthetic substrate. It can be determined that the substrate 1 is not a synthetic substrate by the non-detection of a catalyst. If the substrate 1 included in the capacitor is analyzed and no catalyst is detected on the surface of the substrate 1, it may be considered that the substrate 1 is not a synthetic substrate.

[0090] In the second manufacturing example, the multiple fibrous conductive members 3 may be bonded (e.g., chemically) on the surface of the adhesive layer 11, or their ends may be inserted into the interior of the adhesive layer 11 and bonded (e.g., chemically and / or physically and mechanically). In the latter case, the multiple fibrous conductive members 3 can be more firmly bonded to the adhesive layer 11 by the anchor effect, and peel resistance can be increased.

[0091] The adhesive layer 11 that can be used in the second manufacturing example may be, for example, a cured (or non-fluidized) product of any suitable curable (or flowable) material (e.g., a so-called adhesive). The curable (or flowable) material may be the same as that described above. When a curable (or flowable) material is used, the ends of the multiple fibrous conductive members 3 may be brought into contact with or inserted into the curable (or flowable) material, and the curable material may be hardened (or lose its fluidity), thereby fixing the multiple fibrous conductive members 3 to the adhesive layer 11.

[0092] Alternatively, the adhesive layer 11 usable in the second manufacturing example may be made of, for example, any suitable metal material. The metal material may be titanium, gold, copper, aluminum, etc. When a metal material is used, the ends of the multiple fibrous conductive members 3 may be brought into contact with the metal material (e.g., titanium, gold, etc.) and subjected to high-speed heat treatment, or may be mechanically pressed (pierced) into the metal material (e.g., copper, aluminum, etc.) to fix the multiple fibrous conductive members 3 to the adhesive layer 11.

[0093] According to this embodiment, in addition to the effects described above in the first embodiment, the adhesive layer 11 can firmly adhere the plurality of fibrous conductive members 3 to the substrate 1.

[0094] (Embodiment 3) This embodiment relates to a case where the number density of the fibrous conductive members in the plurality of fibrous conductive members is higher in the proximal half relative to the surface of the substrate than in the distal half, and an adhesive layer is present, but the adhesive layer is not conductive (FIGS. 3A and 3B). (Note that a similar case where the adhesive layer is conductive will be described later with reference to FIG. 8 as a first modified example of embodiment 3.) In this embodiment, similar members to those in embodiments 1 and 2 are given similar numbers, and unless otherwise specified, the explanations in embodiments 1 and 2 may also apply to this embodiment.

[0095] Referring to FIG. 3A, the capacitor 22A of the present embodiment has: A conductive substrate 1; a plurality of fibrous conductive members 3' disposed on the substrate 1 and electrically connected to the substrate 1; a dielectric layer 7 covering the surfaces of the plurality of fibrous conductive members 3'; A conductive layer 9 covering the surface of the dielectric layer 7; Includes.

[0096] Generally speaking, in the capacitor 22A of this embodiment, the multiple fibrous conductive members 3' can be understood as being upside down compared to the multiple fibrous conductive members 3 described above (see Figures 1A, 1B, 2A, and 2B).

[0097] In the present disclosure, one of the proximal half 3p' and the distal half 3d' has a higher number density (d) of the multiple fibrous conductive members 3' and a larger thickness (t) of the dielectric layer 7 than the other.

[0098] More specifically, in this embodiment, the one is the proximal half 3p', and the other is the distal half 3d'. That is, in this embodiment, the proximal half 3p' has a higher number density (d) of the plurality of fibrous conductive members 3' and a larger thickness (t) of the dielectric layer 7 than the distal half 3d'. In other words, the proximal half 3p', in which the number density of the plurality of fibrous conductive members 3' is relatively high, has a larger thickness of the dielectric layer 7 covering the surface of the plurality of fibrous conductive members 3' than the distal half 3d', in which the number density of the plurality of fibrous conductive members 3' is relatively low.

[0099] Thus, in one representative example, the capacitor 22A of this embodiment has a capacitance of d 75 <d 25 And 75 <t 25 In another representative example, the capacitor 22A of the present embodiment may satisfy d 90 <d 10 And 90 <t 10 It may be something that satisfies.

[0100] Although not limiting this embodiment, in one representative example, the number density d of the multiple fibrous conductive members 3' may be small at 0% relative distance from the surface 1a of the substrate 1 to 100%, then increase rapidly to a maximum at about 25%, and decrease (for example, approximately linearly) from there to 100%. For example, d 25 >d 5 >d 75 >d 90 In another representative example, the number density d of the plurality of fibrous conductive members 3' may be large (may be maximum) at 0-10% relative distance from the surface 1a of the substrate 1 from 0% to 100%, and may decrease (for example, approximately linearly) from there to 90-100%. For example, d 10 >d 25 >d 75 >d 90 It may be.

[0101] Although not limiting the present embodiment, the thickness t of the dielectric layer 7 may decrease (for example, approximately linearly) from 0% to 100% relative distance from the surface 1a of the substrate 1. 10 >t 25 >t 75 >t 90 It may be.

[0102] Without being limited to this embodiment, the half of the plurality of fibrous conductive members 3' having a relatively high number density (the one mentioned above, the proximal half 3p' in this embodiment) may have more surface defects than the half of the plurality of fibrous conductive members 3' having a relatively low number density (the other half mentioned above, the distal half 3d' in this embodiment).

[0103] 3A, in the capacitor 22A of this embodiment, a plurality of fibrous conductive members 3' may be bonded to the substrate 1 via an adhesive layer 11. In this embodiment, the adhesive layer 11 does not have electrical conductivity (more specifically, has dielectric / insulating properties).

[0104] As shown in FIG. 3A, the dielectric layer 7 covers the surfaces of the plurality of fibrous conductive members 3' (except for the regions directly bonded to the substrate 1). The conductor layer 9 covers the surface of the dielectric layer 7 (except for the regions embedded in the adhesive layer 11). When the adhesive layer 11 is not conductive as in this embodiment, the conductor layer 9 may not entirely cover the surface 11a of the adhesive layer 11 (except for the regions bonded to the plurality of fibrous conductive members 3' and the dielectric layer 7) (FIG. 3A), or may entirely cover the surface 11a (not shown). When the conductor layer 9 does not entirely cover the surface 11a of the adhesive layer 11, it is preferable to make a modification similar to the second modified example of the second embodiment described later (more specifically, the capacitor 22A further includes a conductor portion 13 in contact with the conductor layer 9), but is not limited thereto.

[0105] The capacitor 22A of this embodiment can be obtained by a manufacturing method including, for example: (a) preparing a plurality of fibrous conductive members 3' disposed on a first substrate and directly bonded to the first substrate at one end, the plurality of fibrous conductive members 3' being composed of a fixed end half located proximal to a surface of the first substrate and a free end half located distal to the surface of the first substrate, the free end half having a higher number density (d) of the plurality of fibrous conductive members 3' than the fixed end half; (b) forming a dielectric layer 7 covering the surfaces of the plurality of fibrous conductive members 3' by a liquid phase deposition method or a sputtering method, and the thickness (t) of the dielectric layer 7 is greater in the free end half than in the fixed end half; (d) exposing the plurality of fibrous conductive members 3' from the dielectric layer 7 at their free end portions opposite the first substrate, bringing the free end portions (portions exposed from the dielectric layer 7) of the plurality of fibrous conductive members 3' into contact with an adhesive layer 11 located on a second substrate having electrical conductivity to transfer the plurality of fibrous conductive members 3' to the second substrate, removing the first substrate from the plurality of fibrous conductive members 3', and then covering the portions of the plurality of fibrous conductive members 3' exposed by removing the first substrate (fixed end portions before transfer) with a dielectric layer; and (c) forming a conductive layer 9 covering the surface of the dielectric layer 7;

[0106] In this embodiment, the first substrate is different from the substrate 1 in the capacitor 22A. Also, in this embodiment, the fixed end half and the free end half of the plurality of fibrous conductive members 3' correspond to the distal half 3d' and the proximal half 3p', respectively, in the capacitor 22A.

[0107] The steps (a) to (b), (d), and (c) are described in more detail below. Note that, although an exemplary case where the fibrous conductive member 3' is VACNT is described below, the fibrous conductive member 3' in this embodiment is not limited to VACNT, and the capacitor 22A may be manufactured using any appropriate method depending on the fibrous conductive member 3' used.

[0108] ·Process (a)~(b) Steps (a) and (b) may be the same as steps (a) and (b) described above in embodiment 1. However, in this embodiment, the first substrate (synthetic substrate) may or may not be conductive.

[0109] ·Process (d) After step (b), the dielectric layer 7 is removed from the free end portions of the VACNTs (the multiple fibrous conductive members 3') on the opposite side of the first substrate to expose the VACNTs from the dielectric layer 7. Any appropriate method may be used to remove the dielectric layer 7, and for example, the dielectric layer 7 can be removed from the free end portions of the VACNTs by cutting off the tips, dissolving the dielectric layer with a chemical solution, or the like.

[0110] Separately, an adhesive layer 11 having no electrical conductivity is formed on the surface of a second substrate (transfer substrate) having electrical conductivity.

[0111] In this embodiment, a conductive substrate 1 is used as the second substrate (transfer substrate).

[0112] In this embodiment, the adhesive layer 11 may be made of any suitable material as long as it is not conductive. For example, as described above in the second manufacturing example of the second embodiment, the adhesive layer 11 may be made of a hardened (or non-fluidized) material of any suitable hardenable (or fluid) material that is not conductive. Unless otherwise specified, the same explanation as in the second manufacturing example of the second embodiment may also be applied to this embodiment.

[0113] Thereafter, the VACNTs and the dielectric layer 7 covering them are inserted into the adhesive layer 11 so that the free end portions (portions exposed from the dielectric layer 7) of the VACNTs (multiple fibrous conductive members 3') are in direct contact with the second substrate, the VACNTs are transferred to the second substrate, and the first substrate is removed from the VACNTs.

[0114] As described above, in this embodiment, the adhesive layer 11 does not have electrical conductivity. If the adhesive layer 11 does not have electrical conductivity, the VACNTs (the plurality of fibrous conductive members 3′) can be forced through the adhesive layer 11 and into the second substrate (substrate 1) to be electrically connected to the second substrate (substrate 1).

[0115] Before being transferred to the second substrate (as directly synthesized on the first substrate), the length (position of the free end) of each CNT may vary due to differences in growth rate, etc., on the free end side of the VACNT (multiple fibrous conductive members 3'). On the other hand, on the fixed end side of the VACNT, the length (position of the fixed end) of each CNT hardly varies and may be considered to be uniform. According to this embodiment, the free end side of the VACNT (multiple fibrous conductive members 3') can be inserted into the adhesive layer 11 by transfer, so that the variation can be absorbed, and the length of the VACNT (multiple fibrous conductive members 3') from the surface of the second substrate (substrate 1) can be made more uniform (compared to, for example, the case of embodiment 1). It is preferable that the thickness of the adhesive layer 11 is larger than the length of the portion where the length of each CNT varies.

[0116] After the transfer, a dielectric is added to the portion (fixed end portion before transfer) of the VACNT (plurality of fibrous conductive members 3') exposed by removing the first substrate, and the exposed portion of the VACNT is covered with a dielectric layer 7. The dielectric can be added using a method similar to that used for forming the dielectric layer in step (b), to the extent that the exposed portion of the VACNT is sufficiently covered.

[0117] ·Process (c) Step (c) may be the same as step (c) described above in embodiment 1.

[0118] As a result of the above, referring again to FIG. 3A, a capacitor 22A can be manufactured which is disposed on a conductive second substrate (which is the same as substrate 1 in this embodiment) and has a plurality of fibrous conductive members 3' (VACNTs) electrically connected to the second substrate, a dielectric layer 7, and a conductor layer 9.

[0119] According to this embodiment, in addition to the effects described above in embodiments 1 and 2, the half of the multiple fibrous conductive members 3' having a relatively high number density (in this embodiment, the proximal half 3p') is transferred to the substrate 1 via an adhesive layer 11, so that the multiple fibrous conductive members 3' can be more firmly bonded to the substrate 1.

[0120] In addition, according to this embodiment, the fixed end half of the multiple fibrous conductive members 3' is the distal half 3d', so that the variation (e.g., in-plane variation) in the length L of the multiple fibrous conductive members 3' can be reduced, and high dimensional uniformity can be obtained.

[0121] (First modified example of the second embodiment) This modified example relates to an example in which the second embodiment is modified so that the thickness of the conductive layer is different (FIG. 4).

[0122] In the capacitor 21B of this embodiment, the conductive layer 9' includes a conductive polymer. The conductive polymer may be the same as that described above in the first embodiment.

[0123] Furthermore, referring to FIG. 4, in the capacitor 21B of this embodiment, the thickness t' of the conductive layer 9' may differ (change) depending on the relative distance from the surface 1a of the substrate 1 (based on the length L of the plurality of fibrous conductive members 3). Without being a limitation of this embodiment, the thickness t' of the conductive layer 9' may decrease (e.g., approximately linearly) from 100% to 0% as the relative distance from the surface 1a of the substrate 1 changes from 100% to 0%. For example, t' 90 >t' 75 >t' 25 >t' 10 The thickness t' of the conductive layer 9' can be measured based on the same concept as in the measurement of the thickness t of the dielectric layer .

[0124] Such a conductive layer 9' can be formed by a liquid phase film formation method. The liquid phase film formation method can be, for example, a sol-gel method, plating, etc. More specifically, the conductive layer 9 can be formed by applying / supplying (for example, by coating or immersion) a liquid composition in which a conductive polymer is dissolved or dispersed in an organic solvent to a predetermined surface / part.

[0125] By appropriately selecting or setting the conditions for performing the liquid phase film formation method, the thickness t' of the formed conductive layer 9' can be made to differ depending on the distance from the surface of the first substrate, and the thickness t' of the conductive layer 9' can be made larger in the free end half than in the fixed end half. When the first substrate is the same as the substrate 1 in the capacitor 21B, the thickness t' of the conductive layer 9' can be made larger in the distal half than in the proximal half with respect to the surface 1a of the substrate 1, as shown in FIG.

[0126] Although this embodiment is not limited thereto, for example, the composition of the liquid used in the liquid phase film formation method, the solvent used for the preparation (e.g., water, ethanol, isopropanol), the film formation time, the stirring speed, the temperature, and the like are appropriately selected or set.

[0127] In this embodiment, the thickness t' of the conductive layer 9' is greater in the distal half of the substrate 1 relative to the surface 1a than in the proximal half, making it easier to make external contact using the thicker portion of the conductive layer 9'.

[0128] (First Modification of the First Embodiment) This modification relates to an example in which the first embodiment is modified by adding another conductive layer (FIG. 5).

[0129] 5, the capacitor 20B of this modified example further includes another conductive layer 5 between the multiple fibrous conductive members 3 and the dielectric layer 7. Such a conductive layer 5 can be understood as an underlying conductive layer for the dielectric layer 7.

[0130] As shown in Figure 5, the conductive layer 5 may cover not only the surfaces of the multiple fibrous conductive members 3 but also the surface 1a of the substrate 1 (excluding the areas joined to the multiple fibrous conductive members 3).

[0131] The material, structure, formation method, etc. of the conductive layer 5 can be similar to those of the conductive layer 9.

[0132] According to this modification, by providing another conductive layer 5 between the plurality of fibrous conductive members 3 and the dielectric layer 7, the equivalent series resistance (ESR) of the capacitor 20B can be reduced.

[0133] (Second modification of the second embodiment) This modified example relates to an example in which a conductive portion in contact with the conductive layer is added to the second embodiment (FIG. 6).

[0134] Capacitor 21C of this modified example further includes a conductor portion 13 in contact with conductor layer 9, as shown in FIG.

[0135] The conductor portion 13 is in contact with the conductor layer 9 and is electrically connected to the conductor layer 9. The conductor portion 13 is not in contact with the dielectric layer 7, the fibrous conductive member 3, the substrate 1, and the adhesive layer 11. The conductor portion 13 is not particularly limited as long as it has conductivity, but for example, the conductor portion 13 can be formed by applying / supplying a conductive paste to a predetermined surface / part. The conductor portion 13 may be, for example, a layer formed in contact with the conductor layer 9 above the plurality of fibrous conductive members 3 covered with the dielectric layer 7 and the conductor layer 9, or may be a layer that fills (for example, partially) the space formed between the plurality of fibrous conductive members 3 covered with the dielectric layer 7 and the conductor layer 9. Note that since the conductive paste generally has a relatively high viscosity, even in the latter case, it is considered that it is difficult to penetrate into the above-mentioned space and does not reach the depth (for example, the bottom) of the space.

[0136] In some cases, the capacitor 21C may further include another substrate (not shown) in contact with the conductor portion 13. If present, the other substrate may cover the conductor portion 13 on the side opposite to the conductor layer 9, and may be, for example, a resin layer. The resin layer may be an exterior resin that seals the element structure (conductor-dielectric-conductor structure) of the capacitor 21C. The resin layer may be formed from any appropriate resin material. The resin material is not particularly limited, and known sealing resin materials may be used, and may be, for example, a thermosetting epoxy resin in which fine particles such as silica are dispersed. However, the other substrate is not limited to a resin layer, and may be made of other materials.

[0137] According to this modified example, external contact can be easily achieved by the conductive portion 13. If present, the separate substrate may be provided with electrodes for contacting the outside and wiring for ensuring electrical conduction.

[0138] (Third Modification of the Second Embodiment) This modified example relates to an example in which, in the second embodiment, when the adhesive layer has electrical conductivity, the electrical connections between the multiple fibrous conductive members and the substrate are modified (FIG. 7).

[0139] In the capacitor 21D of this modified example, the adhesive layer 11 is conductive. In the capacitor 21D, as shown in FIG. 7 , as long as the plurality of fibrous conductive members 3 are in contact with the conductive adhesive layer 11, some or all of the plurality of fibrous conductive members 3 do not need to be in direct contact (directly bonded) with the substrate 1.

[0140] Such a capacitor 21D can be produced by using a conductive adhesive layer 11 in embodiment 2 and further modifying it, for example, as follows: In the first manufacturing example, some or all of the multiple fibrous conductive members 3 may be separated from the substrate 1 due to some factor, and in the second manufacturing example, some or all of the multiple fibrous conductive members 3 may not reach the substrate 1 when the adhesive layer 11 is transferred to the substrate 1 having the surface 1a.

[0141] According to this modified example, since the adhesive layer 11 is conductive, the multiple fibrous conductive members 3 can be reliably set to the same potential or voltage via the adhesive layer 11, regardless of whether they are in contact with the substrate 1 or not, and can be reliably electrically connected to the substrate 1, allowing them to function properly as a capacitor.

[0142] Furthermore, according to this modified example, since adhesive layer 11 has conductivity, the equivalent series resistance (ESR) of capacitor 21D can be reduced.

[0143] (First modified example of the third embodiment) This modified example relates to an example in which the third embodiment is modified so that it can function appropriately as a capacitor when the adhesive layer has electrical conductivity (FIG. 8).

[0144] In the capacitor 22B of this modified example, the adhesive layer 11 is conductive. In the capacitor 22B, as shown in FIG. 8, as long as the plurality of fibrous conductive members 3' are in contact with the conductive adhesive layer 11, some or all of the plurality of fibrous conductive members 3' may not be in direct contact (directly bonded) with the substrate 1. Alternatively, in this modified example, similar to the third embodiment, the plurality of fibrous conductive members 3' may be in direct contact (directly bonded) with the substrate 1 (for example, in this modified example, similar to FIGS. 3A and 3B, the plurality of fibrous conductive members 3' and the dielectric layer 7 may be inserted into and penetrate the adhesive layer 11).

[0145] A dielectric layer 8 is present on the surface 11a of the conductive adhesive layer 11 (except for the areas bonded to the plurality of fibrous conductive members 3' and the dielectric layer 7). The dielectric layer 8 may or may not be integrated with the dielectric layer 7. The dielectric layer 8 is not particularly limited as long as it has dielectric / insulating properties, but may be made of the same material as the dielectric layer 7, for example. The conductive layer 9 may be in contact with the dielectric layer 8, but is not in contact with the fibrous conductive members 3', the adhesive layer 11, and the substrate 1. The conductive layer 9 may not entirely cover (not shown) or may entirely cover (FIG. 8) the surface 8a of the dielectric layer 8 (except for the areas bonded to the plurality of fibrous conductive members 3' and the dielectric layer 7).

[0146] The capacitor 22B can be fabricated, for example, as follows, by using a conductive adhesive layer 11 instead of a non-conductive adhesive layer 11 in the third embodiment. Steps (a) and (b) can be the same as those described in the third embodiment. Step (d) can be the same as those described in the third embodiment, except that the VACNTs and the dielectric layer 7 covering them are placed on the adhesive layer 11 or appropriately inserted into the adhesive layer 11 so that the free end portions (exposed from the dielectric layer 7) of the VACNTs (multiple fibrous conductive members 3') are in direct contact with the adhesive layer 11, and the VACNTs are transferred to the second substrate, and a dielectric is added to the portion (fixed end portion before transfer) of the VACNTs (multiple fibrous conductive members 3') exposed by removing the first substrate after the transfer, and to the exposed portion of the surface 11a of the adhesive layer 11, to cover the exposed portion of the VACNTs with the dielectric layer 7 and form the dielectric layer 8. Step (c) can be the same as those described in the third embodiment.

[0147] In this embodiment, the adhesive layer 11 may be made of any suitable material as long as it is conductive. For example, as described above in the second manufacturing example of embodiment 2, it may be made of a hardened (or non-fluidized) material of any suitable hardenable (or flowable) material that is conductive, or it may be made of any suitable metal. Unless otherwise specified, the same explanation as in the second manufacturing example of embodiment 2 may also apply to this embodiment.

[0148] According to this modified example, since the adhesive layer 11 is conductive, the multiple fibrous conductive members 3' can be reliably set to the same potential or voltage via the adhesive layer 11, regardless of whether they are in contact with the substrate 1 or not, and can be reliably electrically connected to the substrate 1, allowing them to function properly as a capacitor.

[0149] Furthermore, according to this modified example, since adhesive layer 11 has electrical conductivity, the equivalent series resistance (ESR) of capacitor 22B can be reduced.

[0150] Although three embodiments and various modified examples of the present disclosure have been described above, the present disclosure is not limited thereto. For example, any two or more of the features of the above-described embodiments and modified examples may be combined. EXAMPLES

[0151] Example 1 Example 1 relates to the capacitor of embodiment 1, but the formation of the conductive layer is omitted.

[0152] A catalyst was applied to the surface of a Si substrate, and VACNTs were grown. The length of the VACNTs (maximum length of the CNTs) L was about 100 μm, and the outer diameter of the CNTs was about 20 nm. The VACNTs on the Si substrate were then grown on SiO 2More specifically, the VACNTs on the Si substrate were immersed in a raw material mixture of tetraethoxysilane (TEOS) as a raw material and ethanol as a solvent, and the mixture was kept at 25°C for 15 hours while stirring, forming a SiO 2 This resulted in the formation of a dielectric layer of VACNTs and a dielectric (SiO 2 A structure having a ) layer formed thereon was obtained as a sample of Example 1.

[0153] For the sample of Example 1, the space on the dielectric layer that conformed to the shape of the VACNTs was filled with resin, and a cross section parallel to the surface of the Si substrate was exposed by polishing at a specified distance (relative distance 90%) from the surface of the Si substrate (the surface on which the VACNTs were grown). The exposed parallel cross section was observed by SEM, and the number of fibrous conductive members per unit area (CNT number density d) was calculated in a field of view of 3 μm × 3 μm.

[0154] Furthermore, a cross section perpendicular to the surface of the Si substrate was exposed by FIB. The exposed vertical cross section was observed by SEM. The thickness t of the dielectric layer was obtained from the SEM image at a specified relative distance (relative distance 90%). More specifically, the CNT was not tangled and could be recognized as an isolated CNT. The center of the CNT along the longitudinal direction was exposed. The dielectric (SiO 2 ) layers are clearly identifiable (the boundary between the CNT and the dielectric layer, and the boundary between the dielectric layer and the resin layer are clearly identifiable), and the outer diameter D 1 and the outer diameter D of the dielectric layer covering the surface 2 The difference between these outer diameters is then divided by 2 ((D 2 -D 1 The thickness of the dielectric layer was calculated as t / 2. This procedure was repeated to measure the thickness of the dielectric layer for 10 or more CNTs, and the average value was taken as the thickness t of the dielectric layer. 2was measured only for the dielectric layer covering the surface of the CNT. The results are shown in Table 1. In Table 1, the relative distance means the relative distance based on the length L of the VACNT (100 μm in Example 1).

[0155] In the sample in which the parallel cross section and the vertical cross section were exposed at the above-mentioned relative distance of 90%, a cross section parallel to the surface of the Si substrate was further exposed by polishing at a relative distance of 10%, and the CNT number density d at the relative distance of 10% was obtained. Furthermore, a cross section perpendicular to the surface of the Si substrate was exposed by FIB, and the thickness t of the dielectric layer at the relative distance of 10% was obtained. For reference, an example of an SEM image of a parallel cross section cut at a relative distance of 10% of the sample of Example 1 is shown in FIG. 9, and an example of an SEM image of a vertical cross section of the same sample is shown in FIG. 10A and FIG. 10B. FIG. 10B is an enlarged view of part A in FIG. 10A.

[0156] [Table 1]

[0157] If we hypothetically divide the entire VACNT into a proximal half and a distal half with respect to the surface of the Si substrate (considering the proximal half to be the area with a relative distance of less than 50% and the distal half to be the area with a relative distance of 50% or more), the results in Table 1 confirm that the distal half of the VACNT has a higher VACNT number density and a greater dielectric thickness than the proximal half of the VACNT.

[0158] It can be understood that the capacitor of the first embodiment can be fabricated by forming a conductive layer covering the dielectric layer of the sample of the first embodiment by any appropriate method.

[0159] Comparative Example 1 A catalyst was applied to the surface of a Si substrate, and VACNTs were grown. The length of the VACNTs (maximum length of the CNTs) L was about 1000 μm, and the outer diameter of the CNTs was about 20 nm. SiO 2 and Al2 O 3 A dielectric layer was formed by stacking 40 layers of VACNTs and dielectric layer (SiO 2 / Al 2 O 3 A structure having the above laminated layers formed thereon was obtained as a sample of Comparative Example 1.

[0160] For the sample of Comparative Example 1, the thickness t of the dielectric layer and the CNT number density d were determined in the same manner as in Example 1. The results are shown in Table 2. In Table 2, the relative distance means the relative distance based on the length L of the VACNT (1000 μm in Comparative Example 1). For reference, an example of an SEM image of a parallel cross section of the sample of Comparative Example 1 cut at a relative distance of 90% is shown in FIG.

[0161] [Table 2]

[0162] When the entire VACNT is virtually divided into a proximal half and a distal half with respect to the surface of the Si substrate (when the proximal half is considered to be the half with a relative distance of less than 50% and the distal half is considered to be the half with a relative distance of 50% or more), the results in Table 2 confirm that the distal half of the VACNT has a higher number density of VACNTs than the proximal half of the VACNT. Meanwhile, it was confirmed that the thickness of the dielectric in the distal half of the VACNT is slightly smaller than the thickness of the dielectric in the proximal half of the VACNT. However, in Comparative Example 1, the difference in the thickness of the dielectric layer is extremely small with respect to the length L of the VACNT, and it is considered that the thickness of the dielectric is almost uniform regardless of the distance from the surface of the Si substrate. [Industrial Applicability]

[0163] The capacitors of the present disclosure may be used in any suitable application, and may be particularly suitable for applications requiring high capacitance density and a reduced number of short paths.

[0164] This application claims priority based on Patent Application No. 2022-072618 filed in Japan on April 26, 2022, the entire contents of which are incorporated herein by reference.

[0165] <1> A conductive substrate; a plurality of fibrous conductive members disposed on the substrate and electrically connected to the substrate; a dielectric layer covering the surfaces of the plurality of fibrous conductive members; a conductive layer covering a surface of the dielectric layer; the plurality of fibrous conductive members are composed of a proximal half located proximal to a surface of the substrate and a distal half located distal to the surface of the substrate, one of the proximal half and the distal half having a higher number density of the plurality of fibrous conductive members and a larger thickness of the dielectric layer than the other of the proximal half and the distal half. <2> one of the proximal half and the distal half is the distal half and the other of the proximal half is the proximal half; <1> The capacitor according to claim 1 . <3> a number density of the plurality of fibrous conductive members at a distance of 75% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer are greater than a number density of the plurality of fibrous conductive members at a distance of 25% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer, respectively. <2> The capacitor according to claim 1 . <4> a number density of the plurality of fibrous conductive members at a distance of 90% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer are greater than a number density of the plurality of fibrous conductive members at a distance of 10% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer, respectively. <2> The capacitor according to claim 1 . <5> one of the proximal half and the distal half is the proximal half and the other of the proximal half is the distal half; <1> The capacitor according to claim 1 . <6> a number density of the plurality of fibrous conductive members at a distance of 25% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer are greater than a number density of the plurality of fibrous conductive members at a distance of 75% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer, respectively. <5> The capacitor according to claim 1 . <7> a number density of the plurality of fibrous conductive members at a distance of 10% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer are greater than a number density of the plurality of fibrous conductive members at a distance of 90% of the length of the plurality of fibrous conductive members from the surface of the substrate and a thickness of the dielectric layer, respectively. <5> The capacitor according to claim 1 . <8> The plurality of fibrous conductive members are directly bonded to the substrate. <1> ~ <7> 2. The capacitor according to claim 1 . <9> The plurality of fibrous conductive members are bonded to the substrate via an adhesive layer. <1> ~ <7> 2. The capacitor according to claim 1 . <10> one of the proximal half and the distal half has more surface defects on the plurality of fibrous conductive members than the other of the proximal half and the distal half; <1> ~ <9> 2. The capacitor according to claim 1 . <11> Each of the plurality of fibrous conductive members is a carbon nanotube. <1> ~ <10> 2. The capacitor according to claim 1 . <12> The conductive layer includes a conductive polymer. <1> ~ <11> 2. The capacitor according to claim 1 . <13> and further comprising another conductive layer between the surfaces of the plurality of fibrous conductive members and the dielectric layer. <1> ~ <12> 2. The capacitor according to claim 1 . <14> (a) preparing a plurality of fibrous conductive members disposed on a first substrate and directly bonded to a surface of the first substrate at one end, the plurality of fibrous conductive members being composed of a fixed end half located proximal to the surface of the first substrate and a free end half located distal to the surface of the first substrate, the free end half having a higher number density of the plurality of fibrous conductive members than the fixed end half; (b) forming a dielectric layer covering the surfaces of the plurality of fibrous conductive members by a liquid phase deposition method or a sputtering method, the thickness of the dielectric layer being greater in the free end half than in the fixed end half; and (c) forming a conductive layer covering the surface of the dielectric layer; A method for manufacturing a capacitor, comprising: <15> (a) is carried out by applying a catalyst onto the first substrate and growing the plurality of fibrous conductive members from the first substrate; <14> A method for manufacturing the capacitor according to claim 1. <16> the first substrate is conductive; Through the step (c), a capacitor is obtained, the capacitor having the plurality of fibrous conductive members disposed on the first substrate and electrically connected to the first substrate, the dielectric layer, and the conductor layer. <14> or <15> A method for manufacturing the capacitor according to claim 1. <17> After (b) above and before (c) above, (d) exposing the plurality of fibrous conductive members from the dielectric layer at free end portions opposite the first substrate, contacting the free end portions of the plurality of fibrous conductive members with an adhesive layer located on a second substrate having electrical conductivity to transfer the plurality of fibrous conductive members to the second substrate, removing the first substrate from the plurality of fibrous conductive members, and then covering the portions of the plurality of fibrous conductive members exposed by removing the first substrate with a dielectric layer. Further comprising: By the step (c), a capacitor is obtained, the capacitor having the plurality of fibrous conductive members disposed on the second substrate and electrically connected to the second substrate, the dielectric layer, and the conductor layer. <14> or <15> A method for manufacturing the capacitor according to claim 1. [Explanation of symbols]

[0166] 1 Board 1a surface 1b back side 3, 3' A plurality of fibrous conductive members 3p Proximal half (fixed end half) 3d Distal half (free end half) 3p' Proximal half (free end half) 3d' Distal half (fixed end half) 5 Another conductive layer (underlying conductive layer) 7, 8 Dielectric layers 9, 9' Conductive layer 11 Adhesive layer 13 Conductor part 20A, 20B, 21A~21D, 22A, 22B Capacitors L is the length of the multiple fibrous conductive members d Number density of multiple fibrous conductive members t is the thickness of the dielectric layer

Claims

1. A conductive substrate; a plurality of fibrous conductive members disposed on the substrate and electrically connected to the substrate; a dielectric layer covering the surfaces of the plurality of fibrous conductive members; a conductive layer covering a surface of the dielectric layer; the plurality of fibrous conductive members are composed of a proximal half located proximal to a surface of the substrate and a distal half located distal to the surface of the substrate, one of the proximal half and the distal half having a higher number density of the plurality of fibrous conductive members and a larger thickness of the dielectric layer than the other of the proximal half and the distal half.

2. The capacitor of claim 1 , wherein the one of the proximal half and the distal half is the distal half and the other of the proximal half is the proximal half.

3. 3. The capacitor of claim 2, wherein the number density of the fibrous conductive members and the thickness of the dielectric layer at a distance of 75% of the length of the fibrous conductive members from the surface of the substrate are greater than the number density of the fibrous conductive members and the thickness of the dielectric layer at a distance of 25% of the length of the fibrous conductive members from the surface of the substrate.

4. 3. The capacitor of claim 2, wherein the number density of the plurality of fibrous conductive members and the thickness of the dielectric layer at a distance of 90% of the length of the plurality of fibrous conductive members from the surface of the substrate are greater than the number density of the plurality of fibrous conductive members and the thickness of the dielectric layer at a distance of 10% of the length of the plurality of fibrous conductive members from the surface of the substrate.

5. The capacitor of claim 1 , wherein the one of the proximal half and the distal half is the proximal half and the other of the proximal half is the distal half.

6. 6. The capacitor of claim 5, wherein the number density of the fibrous conductive members and the thickness of the dielectric layer at a distance of 25% of the length of the fibrous conductive members from the surface of the substrate are greater than the number density of the fibrous conductive members and the thickness of the dielectric layer at a distance of 75% of the length of the fibrous conductive members from the surface of the substrate.

7. 6. The capacitor of claim 5, wherein the number density of the plurality of fibrous conductive members and the thickness of the dielectric layer at a distance of 10% of the length of the plurality of fibrous conductive members from the surface of the substrate are greater than the number density of the plurality of fibrous conductive members and the thickness of the dielectric layer at a distance of 90% of the length of the plurality of fibrous conductive members from the surface of the substrate.

8. The capacitor according to any one of claims 1 to 7, wherein the plurality of fibrous conductive members are directly bonded to the substrate.

9. The capacitor according to any one of claims 1 to 7, wherein the plurality of fibrous conductive members are bonded to the substrate via an adhesive layer.

10. The capacitor of claim 1 , wherein one of the proximal half and the distal half has more surface defects on the plurality of fibrous conductive members than the other half.

11. The capacitor according to claim 1, wherein each of the plurality of fibrous conductive members is a carbon nanotube.

12. The capacitor according to claim 1 , wherein the conductive layer comprises a conductive polymer.

13. The capacitor according to any one of claims 1 to 7, further comprising another conductive layer between the surfaces of the plurality of fibrous conductive members and the dielectric layer.

14. (a) preparing a plurality of fibrous conductive members disposed on a first substrate and directly bonded to a surface of the first substrate at one end, the plurality of fibrous conductive members being composed of a fixed end half located proximal to the surface of the first substrate and a free end half located distal to the surface of the first substrate, the free end half having a higher number density of the plurality of fibrous conductive members than the fixed end half; (b) forming a dielectric layer covering the surfaces of the plurality of fibrous conductive members by a liquid phase deposition method or a sputtering method, the thickness of the dielectric layer being greater in the free end half than in the fixed end half; and (c) forming a conductive layer covering the surface of the dielectric layer; A method for manufacturing a capacitor, comprising:

15. The method of claim 14 , wherein (a) is performed by applying a catalyst onto the first substrate and growing the plurality of fibrous conductive members from the first substrate.

16. the first substrate is conductive; 16. The method for manufacturing a capacitor according to claim 14 or 15, wherein, through (c), a capacitor is obtained having the plurality of fibrous conductive members arranged on the first substrate and electrically connected to the first substrate, the dielectric layer, and the conductor layer.

17. After (b) and before (c), (d) exposing the plurality of fibrous conductive members from the dielectric layer at free end portions opposite the first substrate, contacting the free end portions of the plurality of fibrous conductive members with an adhesive layer located on a second substrate having electrical conductivity to transfer the plurality of fibrous conductive members to the second substrate, removing the first substrate from the plurality of fibrous conductive members, and then covering the portions of the plurality of fibrous conductive members exposed by removing the first substrate with a dielectric layer. Further comprising:

16. The method for manufacturing a capacitor according to claim 14 or 15, wherein (c) results in a capacitor having the plurality of fibrous conductive members arranged on and electrically connected to the second substrate, the dielectric layer, and the conductor layer.

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