Capacitor

Abstract

Provided is a capacitor that uses a plurality of fibrous conductive members and has high bonding strength between a substrate and a composite bulk member. The capacitor comprises: 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 fibrous conductive members; and a conductive layer covering the surface of the dielectric layer, wherein the plurality of fibrous conductive members, the dielectric layer, the conductive layer, and the spaces formed between the fibrous conductive members covered by the dielectric layer and the conductive layer constitute a composite bulk member, and in a cross section along the thickness direction of the substrate, the composite bulk member has a width W1 on the side away from the substrate and a width W2 on the substrate side, the in-plane direction of the substrate being the width direction, and the width W1 is less than the width W2.

Description

[Technical field]

[0001] The present disclosure relates to capacitors, and more particularly to capacitors having a conductor-dielectric-conductor structure. [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 of forming a capacitor having a metal-insulator-metal (MIM) structure by forming a fibrous member 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 fibrous member. [Prior art documents] [Patent documents]

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

[0004] [Non-Patent Document 1] Michael FL De Volder, Sei Jin Park, Sameh H Tawfick, Daniel O Vidaud and A John Hart, "Fabrication and electrical integration of robust carbon nanotube micropillars by self-directed elastocapillary densification", Journal of Micromechanics and Microengineering, 2011. 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, and then a conductive layer can be formed to form a capacitor having a conductor-dielectric-conductor structure.

[0006] For example, vertically aligned carbon nanotubes (hereinafter, also referred to as "VACNTs") can be used as the multiple fibrous conductive members. VACNTs can be obtained by growing them densely on a substrate to which a catalyst is attached. A forest is formed by multiple VACNTs. In the capacitor, the VACNTs are covered with a dielectric layer and a conductive layer.

[0007] The forest (composite bulk member) covered with the dielectric layer and the conductive layer is in contact with the substrate mainly through the dielectric layer. The substrate and the dielectric layer have different thermal expansion coefficients. Therefore, when the capacitor or its precursor is heated, the difference in thermal expansion coefficients may cause delamination between the substrate and the composite bulk member.

[0008] An object of the present disclosure is to provide a capacitor having high bonding strength between a substrate and a composite bulk member. [Means for solving the problem]

[0009] According to the gist 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 a surface of the fibrous conductive member; a conductive layer covering a surface of the dielectric layer, a plurality of the fibrous conductive members, the dielectric layer, the conductor layer, and spaces formed between the plurality of the fibrous conductive members covered by the dielectric layer and the conductor layer constitute a composite bulk member; In a cross section along a thickness direction of the substrate, The composite bulk member has a width W1 on the opposite side to the substrate and a width W2 on the substrate side, the width being in the in-plane direction of the substrate, and the width W1 is smaller than the width W2, thereby providing a capacitor. Effect of the Invention

[0010] According to the present disclosure, a capacitor is provided in which the bonding strength between the substrate and the composite bulk member is high. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a capacitor according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3A] FIG. 2 is an enlarged view of part B in FIG. [Figure 3B] 2 is a cross-sectional view of part B in FIG. 1 taken along an in-plane direction of the substrate. [Figure 4] FIG. 4 is a schematic cross-sectional view of a capacitor according to a second embodiment of the present disclosure. [Figure 5A] FIG. 5 is an enlarged view of part D in FIG. [Figure 5B] 5 is a cross-sectional view taken along the in-plane direction of the substrate at part D in FIG. 4. [Figure 6] 1 is an optical microscope photograph showing a portion of a cross section of the composite bulk member obtained in Production Example 1 taken along the thickness direction of the substrate. [Figure 7A] FIG. 1 is a schematic cross-sectional view of a conventional capacitor. [Figure 7B] FIG. 1 is a schematic cross-sectional view of a conventional capacitor, showing a state in which a composite bulk member is peeled off. [Figure 8A] 1 is an SEM image of a portion of the outer peripheral region of a polished XZ cross section of a composite bulk member obtained in Manufacturing Example 1. [Figure 8B] 1 is an SEM image of a portion of the central region of a polished XZ cross section of a composite bulk member obtained in Manufacturing Example 1. [Figure 9A] 1 is an SEM image of a portion of the outer peripheral region of a polished XY cross section of a composite bulk member obtained in Manufacturing Example 1. [Figure 9B] 1 is an SEM image of a portion of the central region of a polished XY cross section of a composite bulk member obtained in Manufacturing Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a capacitor according to one aspect of the present disclosure will be described in detail with reference to the illustrated embodiments. Note that the drawings include some schematic views and may not reflect actual dimensions or ratios. The present disclosure is not limited to these embodiments.

[0013] <Embodiment 1> FIG. 1 is a schematic cross-sectional view of a capacitor in the first embodiment. FIG. 1 shows a cross section along the thickness direction of a substrate 10. In FIG. 1, for convenience, the substrate 10 and the outer shape of a composite bulk member 20 are shown, and the fibrous conductive member 21, the dielectric layer 22, and the conductor layer 23 are omitted. FIG. 2 is an enlarged view of part A in FIG. 1. In FIG. 2, the fibrous conductive member 21 sequentially coated with a dielectric layer 22 and a conductor layer 23 is shown. FIG. 3A is an enlarged view of part B in FIG. 1. In FIG. 3A, the fibrous conductive member 21 sequentially coated with a dielectric layer 22 and a conductor layer 23 is shown. FIG. 3B is a cross-sectional view along the in-plane direction of the substrate of part B in FIG. 1. FIG. 3B corresponds to the II cross section of FIG. 3A. For convenience, in FIGS. 3A and 3B, only the substrate 10, the fibrous conductive member 21, the dielectric layer 22, and a part of the conductor layer 23 are shown.

[0014] In the figure, the thickness direction of the substrate 10 is the Z direction. A straight line including the center C of the substrate 10 when the capacitor 1 is viewed from the Z direction and extending along the Z direction is the central axis AX. The center C of the substrate 10 is usually coaxial with the center of the capacitor 1. The direction perpendicular to the Z direction of a cross section obtained by cutting the capacitor 1 along a plane including the central axis AX and extending in the Z direction is the X direction (also referred to as the width direction in an XZ cross section). The X direction is an example of a direction parallel to the in-plane direction of the substrate 10. The direction perpendicular to the Z direction and the X direction is the Y direction (also referred to as the width direction in a YZ cross section).

[0015] The XZ section is a section obtained by cutting the capacitor 1 along a plane formed by a line extending in the X direction and a line extending in the Z direction and including the central axis AX. The XZ section is an example of a section along the thickness direction of the substrate 10. The YZ section is a section obtained by cutting the capacitor 1 along a plane formed by a line extending in the Y direction and a line extending in the Z direction and including the central axis AX. The YZ section is another example of a section along the thickness direction of the substrate 10. The XY section is a section obtained by cutting the capacitor 1 along a plane formed by a line extending in the X direction and a line extending in the Y direction. The XY section is a section parallel to the in-plane direction of the substrate 10. The center C of the substrate 10 is the center of the smallest circle that contains the substrate 10 when the capacitor 1 is viewed from the Z direction.

[0016] In the Z direction, the direction from the substrate 10 to the composite bulk component 20 is sometimes referred to as the upward direction. The upper side of an element refers to the upward side of the element. In the Z direction, the direction from the composite bulk component 20 to the substrate 10 is sometimes referred to as the downward direction. The lower side of an element refers to the downward side of the element. In an XZ cross section, the X direction is sometimes referred to as the left-right direction. The right side of an element refers to the right side of the element. The left side of an element refers to the left side of the element.

[0017] (composition) The capacitor 1 includes a conductive substrate 10, a plurality of fibrous conductive members 21 disposed on the substrate 10 and electrically connected to the substrate 10, a dielectric layer 22 covering the surface of the fibrous conductive members 21, and a conductor layer 23 covering the surface of the dielectric layer 22. The capacitor 1 may have a conductive member (not shown) in contact with the conductor layer 23. The plurality of fibrous conductive members 21, the dielectric layer 22, the conductor layer 23, and spaces 24 formed between the plurality of fibrous conductive members covered by the dielectric layer 22 and the conductor layer 23 constitute a composite bulk member 20. The spaces 24 may be filled with a filler such as a resin. The conductive member will be described later.

[0018] In the capacitor 1, the surface of the substrate 10 can be rephrased as a surface (surface 10a described later) that is parallel to a plane (XY plane) formed by a straight line extending in the X direction and a straight line extending in the Y direction, which is the outer surface of the substrate 10.

[0019] The dielectric layer 22 may cover the surfaces of the fibrous conductive members 21 (excluding the areas directly bonded to the substrate 10) as well as the portions of the surface 10a of the substrate 10 between the plurality of fibrous conductive members 21 where the fibrous conductive members 21 are not arranged. The dielectric layer 22 may be formed on the outside of the plurality of fibrous conductive members 21, continuously with a dielectric portion 22a that covers the portions of the surface 10a of the substrate 10 where the fibrous conductive members 21 are not arranged. However, the composite bulk member 20 does not include the dielectric portion 22a.

[0020] The conductive layer 23 may cover the dielectric layer 22 between the multiple fibrous conductive members 21, in addition to the dielectric layer 22 covering the surface of the fibrous conductive members 21. The portion of the conductive layer 23 that covers the dielectric layer 22 between the multiple fibrous conductive members 21 may be understood as defining the bottom of the space 24 (e.g., the bottom of the trench). The conductive layer 23 may be formed continuously with a conductive portion 23a that covers the dielectric portion 22a outside the multiple fibrous conductive members 21. However, the composite bulk member 20 does not include the conductive portion 23a.

[0021] The fibrous conductive member 21 is directly bonded to the substrate 10. More specifically, the fibrous conductive member 21 is directly contacted and bonded to the substrate 10. The fibrous conductive member 21 is directly synthesized on the surface 10a of the substrate 10.

[0022] The multiple fibrous conductive members 21 are conductive (typically conductors) and can be at the same potential or voltage as one another by being electrically connected to the substrate 10. Thus, a conductor-dielectric-conductor structure is formed by the fibrous conductive members 21, the dielectric layer 22 and the conductor layer 23. Such a conductor-dielectric-conductor structure can be understood as corresponding to a so-called MIM structure (metal-insulator-metal structure). A capacitor 1 having such a structure can obtain a high capacitance density due to the large specific surface area of ​​the fibrous conductive members 21.

[0023] (Composite bulk members) The composite bulk member 20 is composed of a plurality of fibrous conductive members 21 (hereinafter referred to as conductive fibers 21), a dielectric layer 22, a conductor layer 23, and spaces 24 formed between a plurality of conductive fibers 21 (hereinafter also simply referred to as coated conductive fibers 21) coated with the dielectric layer 22 and the conductor layer 23.

[0024] · Method for determining composite bulk member 20 The composite bulk member 20 can be determined from a cross section (e.g., an XZ cross section) in the thickness direction of the capacitor 1. As described above, the composite bulk member 20 does not include the dielectric portion 22a and the conductor portion 23a, and is determined to exclude these. In the following, the XZ cross section will be mainly used as an example of a cross section in the thickness direction.

[0025] First, any suitable filling resin is filled into the spaces 24 formed between the coated conductive fibers 21. Next, the center C of the substrate 10 when the capacitor 1 is viewed from the Z direction is determined.

[0026] A cross section (here, an XZ cross section) in the thickness direction of the capacitor 1 including the center C is exposed by polishing. The obtained XZ cross section (No. 1) is observed with a scanning electron microscope (SEM). In the SEM image of the XZ cross section (No. 1), the substrate 10 and a first member (not shown) arranged on the surface 10a of the substrate 10 and consisting of a conductive fiber 21, a dielectric layer 22 (and a dielectric portion 22a if present, the same below), a conductive layer 23 (and a conductive portion 23a if present, the same below), and a filling resin (corresponding to the above-mentioned space 24) can be confirmed. In addition, a conductive member may be present.

[0027] The SEM image is subjected to image processing to identify and distinguish the conductive fiber 21, the dielectric layer 22, the conductor layer 23, the filling resin (space 24), and further the conductive member in the first member. For the identification, elemental analysis by energy dispersive X-ray analysis (EDX) may be used in combination.

[0028] In the XZ cross section, the composite bulk member 20 is approximately rectangular. In the SEM image, the conductive fibers 21 near the four corners of the composite bulk member 20 are identified. In this identification, the portions of the SEM image including the respective corners may be enlarged so that the observation field of view becomes about 1 μm×1 μm.

[0029] In the SEM image, the leftmost conductive fiber 21, which is the first member closest to the substrate 10 and located at the leftmost position, is identified. Next, the dielectric layer 22 and the conductor layer 23 covering the leftmost conductive fiber 21 are determined. These may be continuous with the dielectric portion 22a and the conductor portion 23a, respectively. The thickness of the dielectric layer 22 (and the dielectric portion 22a, the same below) covering the conductive fiber 21 is approximately uniform in terms of the manufacturing method. Therefore, the outer edge of the dielectric layer 22 covering the leftmost conductive fiber 21 can be determined in consideration of the thickness of the dielectric layer 22 covering the other conductive fibers 21. The thickness of the conductor layer 23 (and the conductor portion 23a, the same below) covering the conductive fiber 21 via the dielectric layer 22 is also approximately uniform in terms of the manufacturing method. Therefore, the outer edge of the conductor layer 23 covering the leftmost conductive fiber 21 can be determined in consideration of the thickness of the conductor layer 23 covering the other conductive fibers 21.

[0030] A first straight line L1 is drawn, which is tangent to the outer edge of the determined conductive layer 23 and parallel to the central axis AX. The point of contact between the first straight line L1 and the conductive layer 23 is the left bottom P1 of the composite bulk member 20. The left bottom P1 is usually located on the surface 10a of the substrate 10. The first straight line L1 defines the boundary (a virtual boundary, the same applies below) between the dielectric layer 22 and the dielectric portion 22a, and the boundary between the conductive layer 23 and the conductive portion 23a. With respect to the first straight line L1, the dielectric layer 22 is located to the right, and the dielectric portion 22a is located to the left. With respect to the first straight line L1, the conductive layer 23 is located to the right, and the conductive portion 23a is located to the left. The dielectric portion 22a and the conductive portion 23a are not included in the composite bulk member 20.

[0031] Similarly, the conductive fiber 21 that is closest to the substrate 10 and located at the rightmost position of the first member is identified, and the dielectric layer 22 and the conductive layer 23 that cover the rightmost conductive fiber 21 are determined. A second straight line L2 that is tangent to the outer edge of the conductive layer 23 and parallel to the central axis AX is drawn. The point of contact between the second straight line L2 and the conductive layer 23 is the right bottom P2 of the composite bulk member 20. The right bottom P2 is usually on the surface 10a of the substrate 10. The second straight line L2 defines the boundary between the dielectric layer 22 and the dielectric portion 22a, and the boundary between the conductive layer 23 and the conductive portion 23a. With respect to the second straight line L2, the dielectric layer 22 is located on the left, and the dielectric portion 22a is located on the right. With respect to the second straight line L2, the conductive layer 23 is located on the left, and the conductive portion 23a is located on the right. The dielectric portion 22a and the conductive portion 23a are not included in the composite bulk member 20.

[0032] Similarly, the conductive fibers 21 located on the leftmost and rightmost sides of the first member on the opposite side to the substrate 10 are identified, and the dielectric layer 22 and conductive layer 23 covering these conductive fibers 21 are determined. A third straight line L3 is drawn, which is tangent to the outer edge of the conductive layer 23 covering the conductive fiber 21 at the left apex and parallel to the central axis AX. The tangency between the third straight line L3 and the conductive layer 23 is the left apex P3 of the composite bulk member 20. A fourth straight line L4 is drawn, which is tangent to the outer edge of the conductive layer 23 covering the conductive fiber 21 at the right apex and parallel to the central axis AX. The tangency between the fourth straight line L4 and the conductive layer 23 is the right apex P4 of the composite bulk member 20.

[0033] Similarly, when the conductive layer 23 and the conductive member are in contact with each other, the outer edge of the conductive layer 23 can be determined taking into consideration the thickness of the conductive layer 23 that covers the other conductive fibers 21. The conductive member is not included in the composite bulk member 20.

[0034] The composite bulk member 20 is composed of a plurality of conductive fibers 21, a dielectric layer 22, a conductor layer 23, and a space 24, which are present in the region between a first line L1 and a second line L2. A rectangle obtained by connecting the left bottom portion P1, the right bottom portion P2, the right top portion P4, and the left top portion P3 represents the outer shape of the composite bulk member 20.

[0035] 〈Widths W1, W2〉 In the cross-section in the thickness direction, the composite bulk member 20 of the present embodiment is a trapezoid in which the upper side (upper side s1) is shorter than the lower side (lower side s2). That is, the composite bulk member 20 has a width W1 on the side opposite to the substrate 10 and a width W2 on the substrate 10 side in the XZ cross-section, and the width W1 is smaller than the width W2 (W1 < W2). Further, in the XZ cross-section of the composite bulk member 20, both the angle θ1 formed by the lower side s2 and the left side (left side s3) and the angle θ2 formed by the lower side s2 and the right side (right side s4) are less than 90 degrees.

[0036] As shown in FIG. 7A, in the XZ cross-section of the composite bulk member 120 in the conventional capacitor 100, the upper side s101 and the lower side s102 are generally the same length (W2), and the four corners are each approximately rectangular with an angle of 90 degrees. When the capacitor 100 or its precursor is heated and cooled, the composite bulk member 120 tends to shrink significantly. However, since the lower side s102 is joined to the substrate 110, it cannot shrink in the X direction, and the shrinkage stress F acts in the Z direction. In addition, since the upper side s101 can shrink without limitation, its shrinkage amount tends to be large. When the shrinkage amount of the upper side s101 increases, the end of the lower side s102 is further pulled in the Z direction. As a result, as shown in FIG. 7B, the composite bulk member 120 peels off from the substrate 110.

[0037] In the present embodiment, since the upper side s1 is shorter than the lower side s2 (W1 < W2), the shrinkage amount of the upper side s1 is smaller than the shrinkage amount of the lower side s2. Further, since the left side s3 and the right side s4 of the composite bulk member 20 are inclined with respect to the Z direction, the shrinkage stress F applied to the lower side s2 is dispersed in the Z direction and the X direction. Due to these reasons, the stress that tries to pull the end of the lower side s2 in the Z direction becomes smaller than that of the conventional one. Therefore, peeling of the composite bulk member 20 from the substrate 10 is suppressed.

[0038] Thus, according to the present disclosure, it is possible to increase the strength of the composite bulk member 20 and suppress peeling while suppressing a decrease in the performance of the capacitor 1 due to unnecessarily thickening the dielectric layer 22 of the entire composite bulk member 20.

[0039] The precursor of the capacitor 1 refers to, for example, a structure including the substrate 10, the plurality of conductive fibers 21, and the dielectric layer 22 before the formation of the conductor layer 23.

[0040] Heating and cooling of the capacitor 1 or its precursor may occur, for example, during the drying process, firing process, and film formation process of the dielectric layer 22, and during the manufacturing process and use of the capacitor 1. Hereinafter, the stress applied in the X direction toward the center of the composite bulk member 20 is referred to as tensile stress.

[0041] The relationship of W1 < W2 only needs to be satisfied in one cross-section in the thickness direction.

[0042] The relationship of W1 < W2 may be satisfied in a plurality of different cross-sections in the thickness direction. The relationship of W1 < W2 may be satisfied in three or more different cross-sections in the thickness direction. The relationship of W1 < W2 may be satisfied in any and all cross-sections in the thickness direction. In this case, the effect of relaxing the tensile stress can be further improved.

[0043] A plurality of different cross-sections in the thickness direction may be an XZ cross-section or a YZ cross-section. A plurality of different cross-sections in the thickness direction can be obtained by rotating the XZ cross-section by less than 360 degrees about the central axis AX.

[0044] · Method for calculating the widths W1 and W2 The width W1 is the distance in the X direction between a straight line including one end of the upper side (upper edge) of the composite bulk member 20 and extending in the Z direction and a straight line including the other end and extending in the Z direction in the XZ cross-section. The width W2 is the distance in the X direction between a straight line including one end of the lower side (lower edge) of the composite bulk member 20 and extending in the Z direction and a straight line including the other end and extending in the Z direction in the XZ cross-section.

[0045] The width W1 is specifically the distance in the X direction between the first straight line L1 and the second straight line L2 as shown in FIG. 1. The width W2 is the distance in the X direction between the third straight line L3 and the fourth straight line L4.

[0046] The widths W1 and W2 in a plurality of cross-sections are calculated as follows. First, for the composite bulk member 20 with the XZ cross-section (No. 1) exposed, another cross-section in the thickness direction (for example, the YZ cross-section. No. 2) is exposed by polishing. The cross-section (No. 2) represents a part (half) of the cross-section in the thickness direction of the composite bulk member 20. The obtained cross-section (No. 2) is observed with an SEM to identify the bottom portions P11 and P21 and the top portions P31 and P41 of the composite bulk member 20 that have been halved (P11 to P41 are not shown). Next, the distance W in the X direction between a straight line including the left bottom portion P11 and extending in the Z direction and a straight line including the right bottom portion P21 and extending in the Z direction 21 and the distance W in the X direction between a straight line including the left top portion P31 and extending in the Z direction and a straight line including the right top portion P41 and extending in the Z direction 11 are obtained.

[0047] As described above, the cross-section (No. 2) represents half of the cross-section in the thickness direction of the composite bulk member 20, but it is acceptable to consider that the remaining half has the same configuration. Therefore, by doubling the distance W 11 the width W1 is obtained. Similarly, by doubling the distance W 21 the width W2 is obtained. By repeating such operations and calculations for a plurality of different cross-sections in the thickness direction as necessary, the widths W1 and W2 in a plurality of cross-sections in the thickness direction can be obtained respectively. For one cross-section in the thickness direction, one width W1 and one width W2 are obtained respectively. In each of the plurality of cross-sections in the thickness direction, the relationship W1 < W2 may be satisfied.

[0048] The upper side s1 is a line segment connecting the left apex P3 and the right apex P4. The lower side s2 is a line segment connecting the left bottom P1 and the right bottom P2. The left side s3 is a line segment connecting the left bottom P1 and the left apex P3. The right side s4 is a line segment connecting the right bottom P2 and the right apex P4. The upper side s1, the lower side s2, the left side s3 and the right side s4 are the outer edge of the composite bulk member 20. In this embodiment, the outer shape of the composite bulk member 20 formed by connecting the above four line segments is approximately trapezoidal.

[0049] <Angle θ1, θ2> In one cross section in the thickness direction, the interior angle θ1 and the interior angle θ2 are both less than 90 degrees. θ1 is the interior angle between the bottom side s2 and the left side s3. θ2 is the interior angle between the bottom side s2 and the right side s4. The angles θ1 and θ2 are measured as follows using the SEM image of the XZ cross section (No. 1) used to calculate the width W1 and the width W2. In the SEM image, the bottoms P1 and P2 and the tops P3 and P4 have already been determined. The left bottom P1 and the right bottom P2 are connected to obtain the bottom side s2. The left bottom P1 and the left top P3 are connected to obtain the left side s3. The right bottom P2 and the right top P4 are connected to obtain the right side s4. The interior angle between the obtained bottom side s2 and the left side s3 is measured to obtain the angle θ1. The interior angle between the bottom side s2 and the right side s4 is measured to determine the angle θ2.

[0050] The relationship of θ1, θ2 < 90 degrees may be satisfied in multiple different thickness direction cross sections. The relationship of θ1, θ2 < 90 degrees may be satisfied in three or more different thickness direction cross sections. The relationship of θ1, θ2 < 90 degrees may be satisfied in any and all thickness direction cross sections. The angles θ1, θ2 in multiple thickness direction cross sections can be measured and estimated using the above YZ cross section (No. 2), etc.

[0051] <Central area R1, outer area R2> The composite bulk member 20 has, in a cross section in the thickness direction, a central region R1 corresponding to the width W1, and peripheral regions R2 on one side and the other side sandwiching the central region R1. The "central region R1 corresponding to the width W1" is a region in the XZ cross section that is sandwiched between a straight line that includes one end of the upper side (top side) of the composite bulk member 20 and extends in the Z direction, and a straight line that includes the other end (the distance in the X direction between these two ends is width W1) and extends in the Z direction.

[0052] 1, the central region R1 is a region sandwiched between a third straight line L3 and a fourth straight line L4 of the composite bulk member 20. The outer circumferential regions R2 are regions other than the central region R1 of the composite bulk member 20, and are disposed in two locations on both ends in the X direction, sandwiching the central region R1. The outer circumferential regions R2 on one side and the other side face each other via the central region R1.

[0053] In the central region R1, the conductive fibers 21 have a maximum height H max The maximum height H max , the width W1 and the width W2 are expressed by the following formula: W2-W1≧1.6×H max may be satisfied.

[0054] (W2-W1) represents the total width of the outer peripheral regions R2 on both sides. It can be said that the larger (W2-W1) is, the greater the inclination of the left side s3 and / or the right side s4 with respect to the central axis AX. From the viewpoint of relaxation of tensile stress, it is desirable that (W2-W1) is as large as possible.

[0055] In particular, (W2-W1) is the maximum height H max When the length W2-W1 is 1.6 times or more, the effect of relaxing the tensile stress is more effectively exhibited. max It may be 2.0 times or more.

[0056] On the other hand, when the outer diameter of the capacitor 1 is taken into consideration, it is desirable that (W2-W1) is not excessively large. Furthermore, from the viewpoint of capacitance, the maximum height H maxIt is desirable to secure a certain degree of. Therefore, (W2-W1) is the maximum height H of the conductive fiber 21. max It may be 50 times or less, or may be 10 times or less.

[0057] W2-W1≧1.6×H max The above relationship only needs to be satisfied in one thickness direction cross section. The above relationship may be satisfied in a plurality of different thickness direction cross sections, in three or more different thickness direction cross sections, or in any all thickness direction cross sections. In this case, the effect of relaxing the tensile stress may be further improved.

[0058] As the contact area between the composite bulk member 20 (particularly the dielectric layer 22) and the substrate 10 increases, the tensile stress applied to the composite bulk member 20 also increases, making it easier for the composite bulk member 20 to peel off. However, according to the present disclosure, when the contact area between the composite bulk member 20 and the substrate 10 is large, for example, the length of the lower side (width W2) is longer than the maximum height H of the conductive fiber 21. max If W2>H max ) peeling of the composite bulk member 20 can also be suppressed.

[0059] Width W2 is the maximum height H max The width W2 may be 4 times or more, or may be 10 times or more. max The width W2 may be 200,000 times or less, 100,000 times or less, or 1,000 times or less. max If it is smaller than four times, the volume of the composite bulk member 20 becomes too small, and the volumetric capacitance density of the capacitor 1 also becomes small.

[0060] Maximum height H max How to determine Maximum height H max is determined from the SEM image of the XZ cross section (No. 1) above. The end of the conductive fiber 21 that is the furthest away from the surface 10a of the substrate 10 in the Z direction is identified, and the distance in the Z direction between this end and the surface 10a is the maximum height H max It is.

[0061] <Width W3, W4> From the viewpoint of relaxing tensile stress, it is desirable that the angles θ1 and θ2 are small, i.e., the inclination of both the left side s3 and the right side s4 with respect to the central axis AX is large. The more the left side s3 and the right side s4 are inclined, the larger the width W3 of the composite bulk member 20 in the outer peripheral region R2 on one side and the width W4 of the composite bulk member 20 in the outer peripheral region R2 on the other side become. The widths W3 and W4 are, for example, determined by the following relationship: W3≧0.8×H max , and W4≧0.8×H max may be satisfied.

[0062] The width W3 is the length in the X direction of the composite bulk member 20 in the left peripheral region R2. The width W4 is the length in the X direction of the composite bulk member 20 in the right peripheral region R2.

[0063] Both W3 and W4 are the maximum height H of the conductive fiber 21. max From the viewpoint of the volumetric capacitance density of the capacitor 1, both W3 and W4 are equal to or greater than the maximum height H max It may be 1,000 times or less, or may be 50 times or less. W3 and W4 may be the same or different.

[0064] W3 and W4 and maximum height H max The above relationship only needs to be satisfied in one cross section in the thickness direction. The above relationship may be satisfied in a plurality of different cross sections in the thickness direction, may be satisfied in three or more different cross sections in the thickness direction, or may be satisfied in any cross sections in all thickness directions.

[0065] How to calculate width W3 and width W4 The widths W3 and W4 are determined using the SEM image of the XZ cross section (No. 1) above. The width W3 is the distance in the X direction between the first straight line L1 and the third straight line L3. The width W4 is the distance in the X direction between the second straight line L2 and the fourth straight line L4.

[0066] 3A, the conductive fibers 21 are inclined with respect to the Z direction or bent in the X direction in the peripheral region R2. This allows at least two conductive fibers 21 to be in contact with each other with or without the dielectric layer 22 in between in the peripheral region R2 (typically, the upper side thereof).

[0067] In this embodiment, if the conductive fibers 21 have high strength (specifically, if the conductive fibers 21 have strength higher than that of the dielectric layer 22), the multiple conductive fibers 21 can support each other in the outer peripheral region R2 of the composite bulk member 20, and the composite bulk member 20 becomes less likely to deform due to an external force. In other words, the lower side s2 becomes even less likely to shrink in the Z direction, and peeling of the composite bulk member 20 from the substrate 10 is further suppressed. In addition, since the conductive fibers 21 can function as a core material, the occurrence of cracks in the composite bulk member 20 due to tensile stress is also suppressed.

[0068] The strength of the conductive fiber 21 is, for example, 5 Mpa / (nm). 2 More than 150Gpa / (nm) 2 As a result, it is expected that the conductive fiber 21 will function as the core material of the composite bulk member 20. The strength of the conductive fiber 21 is 10 Mpa / (nm) or less. 2 or more, 10 Gpa / (nm) 2 The strength of the conductive fiber 21 may be 100 Gpa / (nm) or more. 2 It may be the following:

[0069] 5Mpa / (nm) 2 More than 150Gpa / (nm) 2 The conductive fiber 21 having the following strength may be at least one type selected from the group consisting of carbon nanotubes, metal nanowires, and conductive polymer wires.

[0070] <Area Occupancy Rate S 11 ,S 21 〉 As described above, the conductive fibers 21 of this embodiment are inclined with respect to the Z direction or bent in the X direction in the outer peripheral region R2 of the XZ cross section. Therefore, the space 24 existing in the outer peripheral region R2 is smaller than the space 24 existing in the central region R1. In other words, the outer peripheral region R2 has a smaller area occupancy ratio S of the total area occupied by the conductive fibers 21 and the dielectric layer 22 in the central region R1. 11 The total area occupancy ratio S of the conductive fiber 21 and the dielectric layer 22 compared to 21 Includes high parts.

[0071] If the space 24 is small, the composite bulk member 20 is less likely to deform due to an external force. Therefore, the contraction of the lower side s2 in the Z direction is suppressed. In particular, the deformation of the outer peripheral region R2, which is the starting point of peeling, is suppressed, so that peeling of the composite bulk member 20 from the substrate 10 is further suppressed.

[0072] Area Occupancy Rate S 11 is the total area occupied by the conductive fibers 21 and the dielectric layer 22 in any part of the central region R1 of any one cross section in the thickness direction. 21 is the total area occupied by the conductive fibers 21 and the dielectric layer 22 in any part of the peripheral region R2 of the same cross section as above. 21 is the area occupancy rate S 11 Even if the area occupancy ratio S of the other parts of the outer peripheral region R2 in the cross section is lower than 21 is the area occupancy rate S 11 The higher the better.

[0073] Area Occupancy Rate S 11 ,S 21 The above relationship may be satisfied in a portion of any one cross section in the thickness direction. In any one cross section in the thickness direction, the outer peripheral region R2 on both sides has an area occupancy ratio S 11 Compared to the area occupancy rate S 21This reinforces the central region R1, which is relatively easily deformed, from the left and right, suppressing shrinkage of the entire composite bulk member 20 in the width direction (e.g., X direction). This further facilitates suppression of peeling of the composite bulk member 20 from the substrate 10.

[0074] In a plurality of different cross sections in the thickness direction, the peripheral region R2 has an area occupancy ratio S 11 Compared to the area occupancy rate S 21 In this case, the shrinkage in the width direction of the composite bulk member 20 is further suppressed. "Including high portions in a plurality of thickness direction cross sections" means that the outer peripheral region R2 in at least two different thickness direction cross sections has an area occupancy ratio S 11 Compared to the area occupancy rate S 21 In all cross sections in the thickness direction, the peripheral region R2 includes a portion where the area occupancy ratio S 11 Compared to the area occupancy rate S 21 It is not necessary that the composition include a portion having a high

[0075] In at least two different cross sections in the thickness direction, the outer peripheral region R2 on one side and the outer peripheral region R2 on the other side each have an area occupancy ratio S 11 Compared to the area occupancy rate S 21 may include a portion where

[0076] "Area Occupancy Ratio S 21 "High" refers to the area occupancy rate S 11 and S. 21 This means that the difference between the 21 / S 11 ≧1.05. 21 / S 11 may be 1.2 or more, may be 2 or more, or may be 5 or more.

[0077] Area Occupancy Rate S 11 may be 0.1 or more, may be 0.15 or more, or may be 0.20 or more. 11may be 0.5 or less, may be 0.4 or less, or may be 0.35 or less.

[0078] Area Occupancy Rate S 21 may be 0.2 or more, may be 0.25 or more, or may be 0.30 or more. 21 may be 0.7 or less, may be 0.5 or less, or may be 0.45 or less.

[0079] Area Occupancy Rate S 11 ,S 21 Calculation method Area Occupancy Rate S 11 ,S 21 is calculated as follows using the SEM image of the above XZ cross section (No. 1). In the SEM image, the composite bulk member 20, the peripheral region R2, and the central region R1 are already identified. In the composite bulk member 20, the conductive fiber 21, the dielectric layer 22, the conductive layer 23, and the filled resin (space 24) are distinguished.

[0080] The area of ​​the conductive fiber 21 and the dielectric layer 22 in the right peripheral region R2 is divided by the area of ​​the peripheral region R2 (i.e., the total area including the conductive fiber 21, the dielectric layer 22, the conductor layer 23, and the filled resin). This gives the area occupancy ratio S of the right peripheral region R2. 21 Similarly, the area occupancy ratio S of the left peripheral region R2 is calculated. 21 Similarly, the area occupancy rate S of the central region R1 is calculated. 11 Calculate.

[0081] The observation field of view at this time may be large enough to observe only a part of the central region R1. Similarly, the observation field of view may be large enough to observe only a part of the peripheral region R2. The size of the observation field of view may be, for example, about 1 μm×1 μm. This makes it easier to distinguish between the conductive fiber 21, the dielectric layer 22, the conductor layer 23, and the filling resin.

[0082] Area occupancy ratio S in multiple cross sections in the thickness direction 11 ,S21 The widths W1 and W2 in the thickness direction cross sections may be calculated using the same concept as in the case of calculating the widths W1 and W2 in the thickness direction cross sections. In other words, it may be considered that a part of the outer peripheral region R2 appearing in the thickness direction cross section and the remaining part of the outer peripheral region R2 have the same configuration, and a part of the central region R1 appearing in the thickness direction cross section and the remaining part of the central region R1 have the same configuration.

[0083] <Area Occupancy Rate S 12 ,S 22 〉 The peripheral region R2 is a ratio S of the total area occupied by the conductive fiber 21, the dielectric layer 22, and the conductive layer 23 in the central region R1. 12 The total area occupancy ratio S of the conductive fiber 21, the dielectric layer 22 and the conductive layer 23 compared to 22 That is, S 22 / S 12 ≧1.05. 22 / S 12 may be 1.2 or more, may be 2 or more, or may be 5 or more.

[0084] In the above case, the space 24 is small, so the composite bulk member 20 is less likely to deform due to an external force. Therefore, as described above, the outer peripheral region R2 has an area occupancy ratio S 11 Area occupancy rate S compared to 21 The same effect can be obtained as when the high-temperature portion is included.

[0085] Area Occupancy Rate S 11 The matters described in relation to the area occupancy rate S 12 This can be read as follows: Area Occupancy Rate S 21 The matters described in relation to the area occupancy rate S 22 This can be read as follows and applied.

[0086] Area Occupancy Rate S 12 ,S 22 Calculation method Area Occupancy Rate S 12 ,S 22is calculated by dividing the total area of ​​the conductive fiber 21, the dielectric layer 22, and the conductive layer 23 by the area of ​​the central region R1 or the peripheral region R2. 11 ,S 21 It can be calculated in the same way.

[0087] <Area Occupancy Rate S 13 ,S 23 〉 In the cross section in the thickness direction, the conductive fibers 21 in the outer peripheral region R2 have a width direction component. Therefore, as shown in Fig. 3B, in the XY cross section, the cross-sectional area of ​​the coated conductive fibers 21 in the outer peripheral region R2 is larger than that in the central region R1. In other words, in the XY cross section, as in the XZ cross section, the outer peripheral region R2 has a larger area occupancy ratio S of the total area of ​​the conductive fibers 21, the dielectric layer 22, and the conductor layer 23 in the central region R1. 13 The total area occupancy ratio S of the conductive fiber 21, the dielectric layer 22 and the conductive layer 23 compared to 23 That is, S 23 / S 13 ≧1.05. 23 / S 13 may be 1.2 or more, may be 2 or more, or may be 5 or more.

[0088] Area Occupancy Rate S 13 may be 0.08 or more, may be 0.10 or more, or may be 0.15 or more. 13 may be 0.50 or less, may be 0.40 or less, or may be 0.30 or less.

[0089] Area Occupancy Rate S 23 may be 0.15 or more, may be 0.20 or more, or may be 0.25 or more. 23 may be 0.70 or less, may be 0.50 or less, or may be 0.40 or less.

[0090] 3B corresponds to the cross section II of FIG. 3A. The height H of the cross section II from the surface 10a of the substrate 10 is, for example, a maximum height H maxis 20% or less. The closer the II cross section is to the substrate 10, the larger the cross-sectional area of ​​the coated conductive fiber 21 in the peripheral region R2 can be. One conductive fiber 21 may be disposed so as to straddle the peripheral region R2 and the central region R1.

[0091] Area Occupancy Rate S 13 ,S 23 Calculation method Area Occupancy Rate S 13 ,S 23 can be calculated using the sample used to determine the central region R1 and the peripheral region R2 and its cross section in the thickness direction (XZ cross section). In the XZ cross section, the central region R1 and the peripheral region R2 have already been determined. First, the height H of the sample from the surface 10a of the substrate 10 is the maximum height H max An XY cross section at a first position, which is 20% or less (typically 10% or less) of the XY cross section at the first position, is exposed by polishing. At this time, the XY cross section obtained may cut the dielectric portion 22a or the conductor portion 23a, or may not cut the dielectric portion 22a or the conductor portion 23a. Although the obtained XY cross section shows a part (which may be half or less) of the XY cross section of the composite bulk member 20, the remainder of the XY cross section may be considered to have a similar configuration to the obtained part of the XY cross section.

[0092] The outer shape of the composite bulk member 20 as viewed in the Z direction and in the XY cross section may be, for example, circular, elliptical, or polygonal.

[0093] Next, the central region R1 and the outer circumferential region R2 determined using the XZ cross section are projected onto the obtained XY cross section to determine the central region R1 and the outer circumferential region R2 in the XY cross section.

[0094] Next, the composite bulk member 20 is divided into the conductive fiber 21, the dielectric layer 22, the conductive layer 23, and the filled resin (space 24) by image processing (using EDX analysis as necessary, as in the following), and the area occupancy ratio S 11 ,S 21 Similarly, the area occupancy rate S 13 ,S 23 Calculate.

[0095] <others> Whether the SEM image of the cross section (No. 1) used above is an SEM image of a cross section in the thickness direction of the substrate 10 can be confirmed by the thickness and width of the substrate 10 being observed. If the thickness of the substrate 10 measured from the SEM image is greater than the original thickness of the substrate, the cross section can be determined not to be a cross section in the thickness direction. "Larger than the original thickness of the substrate" means that the thickness of the substrate 10 in the SEM image is 5% or more greater than the original thickness of the substrate 10. Also, if the width of the substrate 10 measured from the SEM image is smaller than the original width of the substrate (the distance between the two intersections of a straight line passing through the center of the substrate and both ends of the substrate), the cross section can also be determined not to be a cross section in the thickness direction. "Smaller than the original width of the substrate" means that the width of the substrate 10 in the SEM image is 5% or more smaller than the original width of the substrate 10.

[0096] In order to confirm that the above SEM image is of a cross section in the thickness direction, it is desirable that the observation field by SEM is wide enough (e.g., 5 μm×5 μm or more) to confirm the front surface 10a, back surface 10b, and both ends of the substrate 10. On the other hand, the observation field may be narrower (e.g., about 1 μm×1 μm) in order to identify and / or distinguish the components of the composite bulk member 20 and calculate the area occupation ratio.

[0097] Whether the SEM image of the XY cross section used above is an SEM image of a cross section parallel to the in-plane direction of the substrate 10 can be confirmed by the cross-sectional shape of the conductive fiber 21. At the first position, most of the conductive fibers 21 extend in the Z direction, and the cross-sectional shape is almost circular. Therefore, if the cross section of the conductive fiber 21 is flat, it can be determined that the cross section is not an XY cross section. "The cross section of the conductive fiber 21 is flat" means that the ratio of the major axis to the minor axis of the cross section of the conductive fiber 21 (major axis / minor axis) is 1.41 or more. The major axis is the longest diameter that passes through the center of the cross section of the conductive fiber 21. The minor axis is the shortest diameter that passes through the center of the cross section of the conductive fiber 21. The center of the cross section of the conductive fiber 21 is the center of the smallest circle that contains the cross section of the conductive fiber 21.

[0098] Each component will be described below. <Conductive fiber> In the present disclosure, the conductive fiber 21 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 the conductive fiber 21 is roughly in the form of a long, thin thread.

[0099] The average length of the conductive fibers 21 may be longer in terms of increasing the capacity density per area. The average length of the conductive fibers 21 may 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 average length of the conductive fibers 21 may be appropriately selected, but the length of the conductive fibers 21 may be, for example, 10 mm or less, 5 mm or less, or 3 mm or less. In one embodiment, the average length of the conductive fibers 21 is 50 μm or more. The average length of the conductive fibers 21 may be 50 μm or more and 3 mm or less.

[0100] The average length of the conductive fibers 21 can be calculated from the SEM image of the XZ cross section (No. 1) above. The average length of the conductive fibers 21 is the average value of the lengths of at least five or more conductive fibers 21.

[0101] The average number density of the conductive fibers 21 (also referred to as the "average number density") may be larger in that the volume density per area can be increased. The average number density of the conductive fibers 21 is, for example, 10 8 book / cm 2 The average number density of the conductive fibers 21 may be, for example, 10 13 book / cm 2 It may be the following:

[0102] In particular, the average length of the conductive fibers 21 is 50 μm or more, and the average number density is 10 8 book / cm 2 This makes it easier for the inclined or bent conductive fibers 21 to come into contact with other conductive fibers 21 in the outer circumferential region R2, and the strength of the composite bulk member 20 is more likely to be increased.

[0103] How to calculate the average number density The average number density of the conductive fibers 21 is the area occupancy ratio S 13 ,S 23 Using the SEM image of the XY cross section used in the calculation of, the average number density N of the composite bulk member 20 is calculated as follows. In the SEM image, the outer edge of the composite bulk member 20 is determined in the same manner as above. The number of conductive fibers 21 present in a portion of the determined composite bulk member 20 (e.g., an area of ​​5 μm × 5 μm) is counted to determine the number of conductive fibers 21 per unit area (number density). This operation is repeated to obtain number densities in five or more fields of view, and the average of these is taken as the average number density N of the composite bulk member 20.

[0104] The maximum cross-sectional dimension of the conductive fiber 21 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 conductive fiber 21 may be, for example, 1 nm or more, or 10 nm or more. The maximum cross-sectional dimension of the conductive fiber 21 may be less than 1000 nm, 800 nm or less, or 600 nm or less.

[0105] The maximum cross-sectional dimension of the conductive fiber 21 is the area occupancy ratio S13 ,S 23 The maximum cross-sectional dimension of the conductive fiber 21 is the average value of the maximum cross-sectional dimensions of at least five or more conductive fibers 21.

[0106] The conductive fiber 21 may be 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 that is conductive (including semiconductive) is also called a nanowire.

[0107] Examples of conductive nanofibers that can be used in the present disclosure include carbon nanofibers. Examples of conductive nanotubes that can be used in the present disclosure include metal nanotubes, organic conductive nanotubes, and inorganic conductive nanotubes. Typically, the conductive nanotubes can be carbon nanotubes or titania carbon nanotubes. Examples of conductive nanorods (nanowires) that can be used in the present disclosure include silicon nanowires, metal nanowires (particularly silver nanowires), and conductive polymer wires. 5Mpa / (nm) 2 More than 150Gpa / (nm) 2 It is desirable for the conductive fiber 21 to have the following strength:

[0108] In particular, the conductive fibers 21 may be carbon nanotubes, which have electrical and thermal conductivity.

[0109] 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.

[0110] 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.

[0111] The conductive fibers 21 may be so-called vertically aligned carbon nanotubes (VACNTs). VACNTs have a large specific surface area. In addition, as described below, VACNTs can be manufactured by growing them in a vertically aligned state on the substrate 10, and therefore the maximum height H max , there is an advantage that the widths W3 and W4 are easily controlled.

[0112] <Substrate> The substrate 10 has two main surfaces (front surface 10a and back surface 10b) facing each other, and may be in the form of, for example, a plate (substrate), a foil, a film, a block, or the like.

[0113] The material constituting the substrate 10 may be appropriately selected as long as it is conductive and can be electrically connected to the plurality of conductive fibers 21. For example, it may 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 10 may 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 10 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.

[0114] The thickness of the substrate 10 is not particularly limited and may vary depending on the application of the capacitor 1. The substrate 10 may be provided with electrodes for contacting the outside and wiring for ensuring electrical conduction. The outer shape of the substrate 10 as viewed from the Z direction may be, for example, a circle, an ellipse, or a polygon.

[0115] <Dielectric layer> The dielectric material constituting the dielectric layer 22 may be appropriately selected. For example, silicon dioxide, aluminum oxide, silicon nitride, tantalum oxide, hafnium oxide, barium titanate, and lead zirconate titanate may be used alone or in combination of two or more (for example, stacked).

[0116] The thickness of the dielectric layer 22 may be 10 nm or more, or may be 15 nm or more. By making the thickness of the dielectric layer 22 10 nm or more, it is possible to increase the insulation property and reduce the leakage current. The thickness of the dielectric layer 22 may be 1 μm or less, or may be 100 nm or less, or may be 70 nm or less. By making the thickness of the dielectric layer 22 1 μm or less, it is possible to obtain a larger electrostatic capacitance. In one embodiment, the thickness of the dielectric layer 22 is 10 nm or more and 1 μm or less.

[0117] The thickness of the dielectric layer 22 is the area occupancy ratio S 13 ,S 23 The thickness of the dielectric layer 22 is the average thickness of the dielectric layer 22 covering at least five or more conductive fibers 21.

[0118] If present, the material constituting the dielectric portion 22 a and the thickness of the dielectric portion 22 a may be similar to that of the dielectric layer 22 .

[0119] Conductive layer Examples of conductive materials constituting the conductor layer 23 include metals and conductive polymers (polymeric materials having conductivity and / or having conductivity imparted thereto, also referred to as organic conductive materials). These may be used alone or in combination of two or more kinds. The conductor layer 23 may be a laminate of multiple layers made of different conductive materials.

[0120] Examples of the metal include silver, gold, copper, platinum, aluminum, and an alloy containing at least two of these metals. Examples of the conductive polymer include PEDOT (polyethylenedioxythiophene), PPy (polypyrrole), and PANI (polyaniline), which may be doped with a dopant such as an organic sulfonic acid compound, for example, polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylicsulfonic acid, polymethacrylicsulfonic acid, poly-2-acrylamido-2-methylpropanesulfonic acid, or polyisoprenesulfonic acid.

[0121] The thickness of the conductor layer 23 may be 3 nm or more, or may be 10 nm or more. By making the thickness of the conductor layer 23 3 nm or more, the resistance value of the conductor layer 23 itself can be reduced. The thickness of the conductor layer 23 may be 500 nm or less, or may be 100 nm or less. In one embodiment, the thickness of the conductor layer 23 is 3 nm or more and 500 nm or less.

[0122] The thickness of the conductive layer 23 is the area occupancy ratio S 13 ,S 23 The thickness of the conductive layer 23 is the average value of the thicknesses of the conductive layer 23 covering at least five or more conductive fibers 21.

[0123] If present, the material constituting conductive portion 23a and the thickness of conductive portion 23a may be similar to that of conductive layer 23.

[0124] ≪Space≫ A space 24 is formed between the coated conductive fibers 21. In the thickness direction cross section and the XY cross section, the space 24 in the outer peripheral region R2 is smaller than that in the central region R1. When the space 24 is smaller, deformation of the composite bulk member 20 is easily suppressed, and the composite bulk member 20 becomes less likely to peel off from the substrate 10.

[0125] <Conductive materials> The capacitor 1 may have a conductive member in contact with the conductive layer 23. The conductive member is electrically connected to the conductive layer 23, and serves to lead the electrode to the outside of the capacitor 1.

[0126] The conductive member does not contact the conductive fiber 21, the dielectric layer 22, or the substrate 10. The boundary between the conductive member and the conductive layer 23 can be confirmed in an SEM image. Alternatively, the boundary between the conductive member and the conductive layer 23 can be identified by elemental analysis using EDX. Furthermore, the boundary between the conductive member and the conductive layer 23 may be determined from the thickness of the conductive layer 23 in the portion not in contact with the conductive member.

[0127] The conductive member is formed, for example, by applying / supplying a carbon paste or a conductive polymer material to a predetermined surface / portion. Carbon paste and conductive polymer materials generally have a relatively high viscosity, and therefore are difficult to penetrate into the space 24 and difficult to reach the depth of the space 24 (for example, the surface 10a of the substrate 10). Therefore, the space 24 is maintained between the coated conductive fibers 21.

[0128] (Manufacturing method) The capacitor 1 of this embodiment can be obtained, for example, by a manufacturing method including the following: (a) preparing a forest consisting of a plurality of conductive fibers 21 disposed on a surface 10a of a substrate 10 and directly bonded at one end to the substrate 10; (b) tilting the conductive fibers 21 on the outside of the forest toward the center; (c) forming a dielectric layer 22 (and a dielectric portion 22a, if present, hereinafter) covering the surfaces of the plurality of conductive fibers 21 by a sol-gel method; and (d) forming a conductive layer 23 (and conductive portion 23a, if present; the same applies below) covering the surface of the dielectric layer 22; Steps (a) to (d) will be described in more detail below.

[0129] Process (a) First, a forest is prepared, which is composed of a plurality of vertically aligned carbon nanotubes (VACNTs) arranged on a substrate 10 and directly bonded to the substrate 10 at one end.

[0130] Step (a) can be carried out by applying a catalyst onto the surface 10a of the substrate 10 and growing a plurality of VACNTs from the surface 10a (in other words, synthesizing them directly on the substrate 10). More specifically, the process is as follows.

[0131] The substrate 10 may be a synthetic substrate for growing VACNTs. 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 10 having electrical conductivity is used as the synthetic substrate.

[0132] First, a catalyst is attached to the surface 10a of the substrate 10. 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 substrate 10, and such techniques may be combined with techniques such as lithography and etching in some cases.

[0133] Then, VACNTs are grown (synthesized directly) on the substrate 10 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 when growing VACNTs. As a result, VACNTs grow on the substrate 10 with the catalyst as a nucleus. The end of the VACNT on the side of the substrate 10 to which the catalyst is attached is the fixed end fixed to the substrate 10 (generally via the catalyst), and the opposite end of the VACNT is the free end, which 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.

[0134] As a result, a forest of VACNTs (conductive fibers 21) is created on the substrate 10. Strictly speaking, the length of each VACNT in the resulting forest may vary (for example, within-plane variation) on the free end side due to differences in growth rate, etc. When VACNTs are grown on the substrate 10 to which a catalyst has been attached, the catalyst may be deactivated midway through the synthesis of the VACNTs, and some carbon nanotubes (CNTs) may stop growing. The CNTs whose growth has stopped become entangled with the continuing growing CNTs and are pulled, causing their fixed ends to separate from the substrate 10 and be pulled up toward the tips of the VACNTs.

[0135] The multiple VACNTs (conductive fibers 21) obtained as described above are placed on the substrate 10, and one end of each VACNT is directly bonded to the substrate 10. However, as will be understood from the above explanation, some of the VACNTs do not need to be directly bonded to the substrate 10.

[0136] Process (b) Next, the VACNTs at the edge of the forest are tilted toward the center. This results in a composite bulk member 20 having a cross section in the thickness direction in which the length of the upper side (W1) is smaller than the length of the lower side (W2) (W1 <W2)。

[0137] By immersing the forest in an appropriate solvent, the VACNTs at the edge of the forest can be tilted toward the center. When the forest is immersed in an appropriate solvent, the VACNTs, especially those on the outside of the forest, tend to aggregate with each other. On the other hand, the VACNTs near the center of the forest tend to remain upright. As a result, the VACNTs at the edge tilt toward the center.

[0138] The solvent is selected in consideration of the wettability of the VACNTs. If the wettability of the VACNTs is too low, the VACNTs do not easily aggregate together. On the other hand, if the wettability of the VACNTs is too high, the VACNTs will excessively aggregate together, making it difficult to obtain a composite bulk member 20 suitable for the capacitor 1. Examples of suitable solvents include water, ethanol, isopropanol, and acetone. Of these, ethanol is preferred.

[0139] A surfactant may be added to the solvent. This allows the wettability of the VACNT to be easily adjusted. The surfactant may be anionic. The surfactant is appropriately selected in consideration of the charge and molecular weight of the hydrophilic group. Examples of the surfactant include sodium dodecyl sulfate, cetyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate. The amount of the surfactant added is appropriately set in consideration of the wettability of the VACNT.

[0140] The material of the dielectric layer 22 may be added to the solvent, so that the bath used in step (b) can be used directly to carry out step (c).

[0141] The immersion conditions are also set taking into consideration the wettability of the VACNTs. Immersion may be performed by immersing the forest-formed substrate 10 in a solvent at room temperature (23°C±3°C) at a speed of 2 to 10 mm / sec (typically 5 mm / sec) so that the angle between the substrate 10 and the liquid surface is approximately 90 degrees, in order to prevent excessive aggregation. After immersing the forest in the solvent, it can be pulled out and dried, causing the VACNTs on the outside of the forest to be significantly tilted or bent toward the center.

[0142] Forest aggregation is also described in Non-Patent Document 1.

[0143] Process (c) Next, a dielectric layer 22 that covers at least the surface of the VACNTs is formed by a sol-gel method.

[0144] A film formed by a liquid phase film formation method, such as a sol-gel method, is likely to contain impurities and volatile components. Such impurities and volatile components are easily desorbed by heating, so the film tends to shrink more, and the tensile stress applied to the composite bulk member 20 also becomes larger. However, according to the composite bulk member 20 of the present disclosure, even when the dielectric layer 22 is formed by a liquid phase film formation method, peeling from the substrate 10 is suppressed.

[0145] By appropriately selecting or setting the conditions for carrying out the sol-gel method, it is possible to control the thickness of the formed dielectric layer 22. For example, the feed composition of the liquid used in the liquid phase film formation method, the solvent used for the feed (e.g., water, ethanol, isopropanol, acetone), the film formation time, the stirring speed, the temperature, etc. may be appropriately selected or set.

[0146] As described above, when the material of the dielectric layer 22 is added to the solvent used in step (b), step (b) and step (c) are performed simultaneously or continuously in the same bath. In other words, the aggregation of VACNTs and the attachment of the material of the dielectric layer 22 proceed simultaneously or continuously. The attachment of the material of the dielectric layer 22 to the surface of the VACNTs makes it easier to maintain an appropriate aggregation state between the VACNTs, and further progression of aggregation due to the subsequent drying is suppressed. In this way, in terms of the ease of controlling the aggregation state, step (b) and step (c) may be performed simultaneously or continuously. In this case, the film formation time may be 1 to 3 hours (typically 1.5 hours), and the stirring speed may be 150 to 500 rpm (typically 300 rpm). Other conditions may be the same as the immersion conditions in step (b).

[0147] Thereafter, the solvent is removed by drying to form the dielectric layer 22.

[0148] Process (d) Subsequently, a conductive layer 23 is formed to cover the surface of the dielectric layer 22 .

[0149] The method for forming the conductive layer 23 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.

[0150] For example, the conductor layer 23 can be formed by a liquid phase film formation method using a conductive polymer. More specifically, the conductor layer 23 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 conductive fibers 21 covered with the dielectric layer 22, and the conductor layer 23 can be appropriately formed even in the deep part of the space (e.g., the bottom part).

[0151] In this manner, the capacitor 1 shown in FIGS. 1, 2, 3A, and 3B can be manufactured.

[0152] <Embodiment 2> Fig. 4 is a schematic cross-sectional view of a capacitor in embodiment 2. Fig. 4 is a cross-section corresponding to Fig. 1. Fig. 5A is an enlarged view of part D in Fig. 4, and corresponds to Fig. 3A. Fig. 5B is a cross-sectional view of part D in Fig. 4 along the in-plane direction of the substrate. Fig. 5B corresponds to the II-II cross-section in Fig. 5A. For convenience, Figs. 5A and 5B show only a portion of the substrate 10, the conductive fiber 21, the dielectric layer 22, and the conductive layer 23.

[0153] The second embodiment differs from the first embodiment in the outer shape of the composite bulk member. This difference in configuration will be described below. The other configurations are the same as those of the first embodiment, and the same reference numerals as those of the first embodiment are used, and the description thereof will be omitted.

[0154] <Outer edge> 4, in the capacitor 1A of the second embodiment, the composite bulk member 20A has an outer edge portion 20a extending parallel to the width direction in the outer peripheral region R2 of the cross section in the thickness direction. The outer edge portion 20a corresponds to at least a part of the outer peripheral region R2 and includes at least a part of the outer edge of the composite bulk member 20A.

[0155] Unlike the dielectric portion 22a and the conductor portion 23a, the outer edge portion 20a includes the conductive fibers 21. As shown in FIGS. 5A and 5B, in the outer edge portion 20a in the XZ cross section, the conductive fibers 21 include first portions 21a extending parallel to the X direction. That is, in the outer edge portion 20a, at least a portion of the conductive fibers 21 is inclined so as to extend parallel to the X direction. Therefore, the space 24 existing in the outer edge portion 20a is even smaller. This makes the composite bulk member 20A more resistant to deformation, and further suppresses peeling from the substrate 10.

[0156] In addition, the first portion 21a increases the contact area between the conductive fiber 21 and the substrate 10 and reduces the contact area between the dielectric layer 22 and the substrate 10, thereby reducing the effect of the difference in thermal expansion and further suppressing peeling of the composite bulk member 20A.

[0157] When the conductive fibers 21 have high strength, the first portion 21a effectively functions as a core material of the fibers 21, and also suppresses the occurrence of cracks in the composite bulk member 20A due to tensile stress. Furthermore, the contact area between the conductive fibers 21 at the outer edge portion 20a increases, thereby increasing the mechanical strength of the composite bulk member 20A, and further enhancing the effect of suppressing deformation of the composite bulk member 20A.

[0158] Although not shown in FIG. 5A, a coated conductive fiber 21 is present near the left apex P3 of the composite bulk member 20, and this coated conductive fiber 21 determines the left apex P3.

[0159] "Parallel" with respect to the outer edge 20a means that the acute angle θa (not shown) between the tangent to the surface of the composite bulk member 20A (i.e., the surface of the conductive layer 23) and the surface 10a of the substrate 10 is 30 degrees or less. The upper surface of the outer edge 20a may have fine irregularities caused by the dielectric layer 22 and / or the conductive layer 23. When observed with a field of view of 5 μm × 5 μm or more, if the acute angle θa is 30 degrees or less, the outer edge 20a is deemed to extend parallel to the width direction without taking into account these fine irregularities.

[0160] The term "parallel" with respect to the first portion 21a means that the acute angle θb (not shown) between the upper surface of the conductive fiber 21 and the surface 10a of the substrate 10 is 30 degrees or less.

[0161] 5A, the conductive fiber 21 may have a second portion 21b other than the first portion 21a in the outer peripheral region R2. The second portion 21b is a portion of the conductive fiber 21 extending along the Z direction or in a direction that forms an acute angle (not shown) with the Z direction that is greater than 0 degrees and less than 60 degrees. The second portion 21b may be disposed in the outer edge portion 20a together with the first portion 21a of the conductive fiber 21.

[0162] The length L and maximum height H of the first portion 21a max is expressed by the following relation: L≧0.8×H max It is acceptable for the above conditions to be met.

[0163] Maximum height H max It is acceptable to consider that represents the entire length of one conductive fiber 21. By having 80% or more of the entire length of the conductive fiber 21 extend parallel to the X direction, the contact area between the conductive fiber 21 and the substrate 10 is further increased, and the effect of suppressing peeling of the composite bulk member 20A from the substrate 10 is further improved. In particular, the length L and the maximum height H max That is, L ≧ 1.0 × H max The relationship between length L and maximum height H max That is, L≦10×H max The above relationship may be satisfied.

[0164] In the outer edge portion 20a, the plurality of conductive fibers 21 may each have a first portion 21a. The first portion 21a of at least one of the plurality of conductive fibers 21 satisfies the above-mentioned relational expression (L≧0.8×H max ) is sufficient.

[0165] Method for determining the first portion 21a The first portion 21a is determined as follows using an SEM image of a cross section (e.g., an XZ cross section) in the thickness direction of the composite bulk member 20A. First, the outer peripheral region R2 in the XZ cross section is determined in the same manner as described above. In the conductive fibers 21 present in the outer peripheral region R2, the acute angle θb formed between the upper surface of the conductive fibers 21 and the surface 10a of the substrate 10 is measured from the outer edge side of the composite bulk member 20A toward the central axis AX. The observation field of view at this time may be large enough to confirm the entirety of one of the outer peripheral regions R2.

[0166] As shown in Fig. 5A, the point where the acute angle θb becomes 30 degrees or less for the first time is one end P7 of the first portion 21a. When P7 is in the vicinity of the outer edge of the outer circumferential region R2, one end of the first portion 21a may be regarded as the outermost portion of the conductive fiber 21. In Fig. 5A, since the end P7 is in the vicinity of the outer edge of the outer circumferential region R2, the outermost portion of the conductive fiber 21 is regarded as one end of the first portion 21a.

[0167] The point where the acute angle θb exceeds 30 degrees and thereafter no decrease in the acute angle θb is the other end P8 of the first portion 21a. The part of the conductive fiber 21 corresponding to the region sandwiched between the one end P7 or the outer end of the conductive fiber 21 and the other end P8 is the first portion 21a.

[0168] Method for determining the outer edge portion 20a The outer edge 20a is determined from the SEM image of the XZ cross section used to determine the first portion 21a as follows. In the SEM image, the acute angle θa between the tangent to the surface of the composite bulk member 20A and the surface 10a of the substrate 10 is measured from the outer edge of the composite bulk member 20A toward the central axis AX. As described above, the observation field of view at this time is set to 5 μm × 5 μm or more.

[0169] The first point where the acute angle θa becomes 30 degrees or less is one end P5 on the upper surface side of the outer edge portion 20a, as shown in Fig. 5A. When P5 is near the outer edge of the outer peripheral region R2, one end of the outer edge portion 20a may be regarded as the outermost part of the outer peripheral region R2. In Fig. 5A, since the end P5 is near the outer edge of the outer peripheral region R2, the outermost part of the outer peripheral region R2 is regarded as one end of the outer edge portion 20a.

[0170] The point where the acute angle θa exceeds 30 degrees and thereafter does not decrease is the other end P6 on the upper surface side of the outer edge portion 20a. The composite bulk member 20A corresponding to the region sandwiched between the one end P5 or one end of the outer peripheral region R2 and the other end P6 is the outer edge portion 20a.

[0171] The outer edge portion 20a may be present in one cross section in the thickness direction. The outer edge portion 20a may be present in a plurality of different cross sections in the thickness direction, may be present in three or more different cross sections in the thickness direction, or may be present in any cross sections in the thickness direction. In this case, peeling of the composite bulk member 20A from the substrate 10 is further suppressed.

[0172] In the cross section in the thickness direction, the outer edge portion 20a may be present in at least one of the outer peripheral regions R2 on one side and the other side. The outer edge portion 20a may be present in the outer peripheral regions R2 on both sides. The first portion 21a of the conductive fiber 21 may be disposed in a part of the outer edge portion 20a, or may be disposed over the entire outer edge portion 20a.

[0173] The outer edge portion 20a may or may not coincide with the outer peripheral region R2. The width W5 of the outer edge portion 20a may be 30% or more and 100% or less of the width W3 or width W4 of the outer peripheral region. The width W5 of the outer edge portion 20a may be 40% or more, or may be 50% or more of the width W3 or width W4 of the outer peripheral region.

[0174] The width W5 of the outer edge 20a is determined as follows using the SEM image of the XZ cross section used to determine the outer edge 20a: The distance in the X direction between a straight line that includes one end P5 of the outer edge 20a or one end of the outer peripheral region R2 determined above and extends in the Z direction, and a straight line that includes the other end P6 of the outer edge 20a and extends in the Z direction, is the width W5.

[0175] How to determine length L The length L of the first portion 21a is the length of the first portion 21a in the X direction. The length L of the first portion 21a is determined as follows using the SEM image of the XZ cross section used to determine the outer edge portion 20a. The distance in the X direction between a straight line that includes one end P7 of the first portion 21a determined above or the outer end of the conductive fiber 21 and extends in the Z direction, and a straight line that includes the other end P8 of the first portion 21a and extends in the Z direction, is the length L.

[0176] As shown in FIG. 4, in the XZ cross section, the outer edge portion 20a has a height H O It has a height H O and maximum height H max is expressed by the following relation: H O ≦0.2×H max may be satisfied.

[0177] Height H O How to determine Height H of outer edge 20a O is the maximum height H of the conductive fiber 21 max From the viewpoint of capacity, the height H of the outer edge portion 20a may be 0.01 times or less. O is the maximum height H of the conductive fiber 21 max It may be 0.0001 times or more.

[0178] Height H of outer edge 20a Ois measured as follows, using the XZ cross section used to determine the outer edge 20a. The outer edge 20a has already been determined in that cross section. The distance in the Z direction from the surface 10a of the substrate 10 to any point on the surface above the outer edge 20a is obtained. This operation is repeated to obtain the above distances at five or more points, and the average of these distances is taken as the height H of the outer edge 20a. O Let us assume that.

[0179] <Area Occupancy Rate S 24 〉 In the cross section in the thickness direction, the outer edge portion 20a has an area occupancy ratio S of the total area of ​​the conductive fibers 21 and the dielectric layer 22 in the central region R1. 11 The total area occupancy ratio S of the conductive fiber 21 and the dielectric layer 22 compared to 24 That is, S 24 / S 11 Satisfy ≧ 1.05. Area Occupancy Rate S 24 is the area occupancy rate S 21 It is calculated in the same way.

[0180] Area Occupancy Rate S 11 and S. 24 The above relationship only needs to be satisfied in one cross section in the thickness direction. The above relationship may be satisfied in a plurality of different cross sections in the thickness direction, may be satisfied in three or more different cross sections in the thickness direction, or may be satisfied in any cross sections in all thickness directions.

[0181] Although two embodiments of the present disclosure have been described in detail above, the present disclosure is not limited thereto. For example, any two or more of the features of the above-described embodiments may be combined.

[0182] In the composite bulk members 20 and 20A of the above-described embodiments, the length of the upper side s1 is equal to the width W1, and the length of the lower side s2 is equal to the width W2, but this is not limited thereto. In some cases, such as when the upper side s1 and the lower side s2 are not parallel, the length of the upper side s1 may be longer than the width W1.

[0183] In the composite bulk member 20 of the above-described embodiment, the interior angle θ1 between the lower side s2 and the left side s3 (i.e., one end side of the composite bulk member 20 in the width direction) and the interior angle θ2 between the lower side s2 and the right side s4 (i.e., the other end side of the composite bulk member 20 in the width direction) are both less than 90 degrees, but are not limited to this. At least one of the interior angles θ1, θ2 may be less than 90 degrees. In particular, both of the interior angles θ1, θ2 may be less than 90 degrees.

[0184] In the composite bulk member 20, 20A of the above-mentioned embodiment, the outer peripheral region R2 is disposed at two locations on both ends in the width direction of the central region R1, but is not limited to this. The outer peripheral region R2 may be disposed only at one end in the X direction of the central region R1 in the cross section in the thickness direction of the composite bulk member 20, 20A.

[0185] In the composite bulk members 20 and 20A of the above-described embodiments, the conductive fibers 21 are directly bonded to the substrate 10, but this is not limiting. The conductive fibers 21 may be bonded to the substrate 10 via a conductive adhesive layer. The conductive fibers 21 may be bonded to the surface of the adhesive layer, or may be bonded to the adhesive layer by inserting their ends into the adhesive layer. The conductive adhesive layer is typically formed of a metal material.

[0186] In the composite bulk member 20, 20A of the above-mentioned embodiment, the conductive fibers 21 in the peripheral region R2 are inclined or bent, but are not limited thereto. The conductive fibers 21 in the peripheral region R2 may extend in the Z direction. In this case, the conductive fibers 21 in the peripheral region R2 are shorter than the conductive fibers 21 in the central region R1.

[0187] In the composite bulk member 20, 20A of the above-described embodiment, the conductive fibers 21 in the outer peripheral region R2 are in contact with each other with or without the dielectric layer 22 interposed therebetween, but are not limited to this. The multiple conductive fibers 21 in the outer peripheral region R2 may be isolated from each other.

[0188] In the capacitors A and 1A of the above-described embodiments, the conductive fibers 21 and / or the composite bulk members 20 and 20A may be present on the surface (side surface) of the substrate 10 connecting the front surface 10a and the back surface 10b.

[0189] In the above embodiment, in step (a), carbon nanotubes (CNTs) are used as the conductive fibers 21. However, the conductive fibers 21 are not limited to these. The conductive fibers 21 may be other than CNTs.

[0190] In the above-described embodiment, in step (a), a forest is provided on the substrate 10, but this is not limiting. The forest may be provided on another synthetic substrate and then transferred to the substrate 10. In this case, steps (b) and after may be performed after the transfer. An adhesive layer may be provided on the substrate 10.

[0191] In the above-described embodiment, in step (b), the cross-sectional shape of the forest is made trapezoidal by inclining a part of the conductive fibers 21, but this is not limited to the above. In step (a), the growth rate of the conductive fibers 21 that form the edge of the forest may be reduced to make the cross-sectional shape of the forest trapezoidal. In this case, step (b) is omitted.

[0192] In the above-described embodiment, in step (b), a part of the conductive fibers 21 is tilted by aggregation, but this is not limiting. A part of the conductive fibers 21 may be tilted by pressing the forest from the outside toward the center.

[0193] In the above-described embodiment, the dielectric layer 22 is formed by a sol-gel method in step (c), but the present invention is not limited to this. The dielectric layer 22 may be formed by a vapor phase film formation method (typically, a sputtering method). In this case, the solvent used in step (b) is removed before performing step (c). The dielectric layer 22 may be formed by a liquid phase film formation method (typically, a plating method) other than the sol-gel method. When the dielectric layer 22 is made of a metal oxide, a method in which plating and surface oxidation treatment are combined may be used. EXAMPLES

[0194] The present invention will be described more specifically with reference to the following Production Examples, but the present invention is not limited thereto. (Production Example 1) A capacitor 1A having the composite bulk member 20A of the above-described embodiment was manufactured.

[0195] (1) Forest preparation A catalyst was applied onto the surface of the Si substrate 10, and VACNTs were grown to obtain a forest 200. The maximum height of the forest 200 (maximum height H max The diameter of the CNTs was 105 μm, and the outer diameter of the CNTs was about 20 nm. The number density of CNTs in the forest was 3.99 × 10 8 book / cm 2 The number density of the CNTs in the forest 200 can be regarded as the average number density of the conductive fibers 21 in the composite bulk member 20.

[0196] (2) Formation of CNT gradient and dielectric layer The substrate 10 on which the forest 200 was provided was immersed in a raw material liquid containing sodium dodecyl sulfate, ammonia, 3-aminopropyltriethoxysilane and ethanol. The immersion was carried out as follows. First, the substrate 10 on which the forest 200 was provided was placed in the raw material liquid at room temperature (23°C ± 3°C) so that the angle between the substrate 10 and the liquid surface of the raw material liquid was approximately 90 degrees. The immersion speed was 5 mm / sec. After maintaining the liquid at 25°C for 1.5 hours while stirring at 300 rpm, the substrate was pulled out. Finally, the substrate was dried to form a dielectric layer 22 (SiO2) covering the surfaces of the multiple CNTs (conductive fibers 21) on the substrate 10.

[0197] (3) Formation of the conductive layer Next, the substrate 10 was immersed in a dispersion liquid containing PEDOT (polyethylenedioxythiophene) and PSS (polystyrene sulfonic acid) to form a conductive layer 23 (a PEDOT / PSS composite) on the dielectric layer 22. In this manner, a capacitor 1A was obtained.

[0198] After filling the spaces present in the composite bulk member 20A of the obtained capacitor 1A with resin, the center C of the substrate 10 was determined by viewing the substrate 10 from the Z direction. Next, the XZ cross section including the center C was exposed by polishing. The obtained cross section was observed by SEM. It can be seen that the average length of the fibrous conductive members is 50 μm or more, and the thickness of the dielectric layer is 10 nm or more.

[0199] An SEM image of a portion of the cross section is shown in Fig. 6. In Fig. 6, a composite bulk component 30 is also present on the side surface 10c of the composite bulk component 20A. For convenience, dashed lines are added in Fig. 6 to indicate the outer edges of the composite bulk components 20A and 30 and the substrate 10.

[0200] From the SEM image in which the entire cross section can be observed, the left bottom part P1, the right bottom part P2, the left top part P3, and the right top part P4 of the composite bulk member 20A were determined in the same manner as described above. max The width W1 was 4.76 mm, W2 was 5.00 mm, W2-W1 was 240 μm, and H max The width W1, W2, W3, and W4 are W1 <W2、W2-W1≧1.6×H max , and W2>H max The relationship is satisfied, and W3≧0.8×H max , W4≧0.8×H max If the line segment connecting the left base P1 and the right base P2 is the bottom side s2, the line segment connecting the left base P1 and the left apex P3 is the left side s3, and the line segment connecting the right base P2 and the right apex P4 is the right side s4, the interior angle θ1 between the bottom side s2 and the left side s3 is 73.6 degrees, and the interior angle θ2 between the bottom side s2 and the right side s4 is 54.4 degrees.

[0201] In any cross section in the thickness direction, the outer peripheral regions R2 on both sides have an area occupancy ratio S of the central region R1. 12 Compared to the area occupancy rate S 22 The area occupancy rate was S 22 / S 12≧1.36. As a result, the area occupancy ratio S of the central region R1 was satisfied for both the one side and the other side peripheral region R2. 11 Compared to the area occupancy rate S 21 It can be understood that this includes high parts.

[0202] In at least one cross section in the in-plane direction, the peripheral region R2 has an area occupancy ratio S of the central region R1. 13 Compared to the area occupancy rate S 23 The area occupancy rate was S 23 / S 13 The relationship was ≥ 1.53.

[0203] The maximum cross-sectional dimension of the CNT calculated from the in-plane cross section was 33 nm. The thickness of the dielectric layer 22 was 51 nm. The thickness of the conductive layer 23 was 15 nm.

[0204] Fig. 8A is an SEM image of a part of the outer peripheral region of the polished XZ cross section of the composite bulk member obtained in Manufacturing Example 1. Fig. 8B is an SEM image of a part of the central region of the polished XZ cross section of the composite bulk member obtained in Manufacturing Example 1. In Figs. 8A and 8B, the linear whitish parts are the conductive fibers 21 covered with the dielectric layer 22 and the conductive layer 23, and the black parts are the filled resin corresponding to the space 24.

[0205] Fig. 9A is an SEM image of a part of the outer peripheral region of the polished XY cross section of the composite bulk member obtained in Manufacturing Example 1. Fig. 9B is an SEM image of a part of the central region of the polished XY cross section of the composite bulk member obtained in Manufacturing Example 1. In Figs. 9A and 9B, the circular whitish parts are the conductive fibers 21 covered with the dielectric layer 22 and the conductive layer 23, and the black parts are the filled resin corresponding to the spaces 24. [Industrial Applicability]

[0206] The capacitors of the present disclosure may be used in any suitable application, particularly in applications where high bond strength between a substrate and a composite bulk member is required.

[0207] This application claims priority based on Japanese Patent Application No. 2022-175699, filed in Japan on November 1, 2022, the entire contents of which are incorporated herein by reference.

[0208] <1> A conductive substrate; a plurality of fibrous conductive members disposed on the substrate and electrically connected to the substrate; a dielectric layer covering a surface of the fibrous conductive member; a conductive layer covering a surface of the dielectric layer, a plurality of the fibrous conductive members, the dielectric layer, the conductor layer, and spaces formed between the plurality of the fibrous conductive members covered by the dielectric layer and the conductor layer constitute a composite bulk member; In a cross section along a thickness direction of the substrate, A capacitor, wherein the composite bulk member has a width W1 on the opposite side to the substrate and a width W2 on the substrate side, with the width direction being the in-plane direction of the substrate, and the width W1 is smaller than the width W2. <2> In a cross section along a thickness direction of the substrate, The fibrous conductive member has a maximum height H max having The width W1, the width W2 and the maximum height H max But the following relation: W2-W1≧1.6×H max Fulfilling <1> The capacitor according to claim 1 . <3> In a cross section along a thickness direction of the substrate, The composite bulk member has widths W3 and W4 at outer peripheral regions on one side and the other side sandwiching a central region corresponding to the width W1, The width W3, the width W4 and the maximum height H max But the following relation: W3≧0.8×H max , and W4≧0.8×H max Fulfilling <2> The capacitor according to claim 1 . <4> In a cross section along a thickness direction of the substrate, In at least one of the outer peripheral regions of the composite bulk member on one side and the other side sandwiching the central region corresponding to the width W1, The fibrous conductive member has a first portion extending parallel to an in-plane direction of the substrate. <1> ~ <3> 2. The capacitor according to claim 1 . <5> In a cross section along a thickness direction of the substrate, The fibrous conductive member has a maximum height H max having The length L of the first portion, and the maximum height H max But the following relation: L≧0.8×H max Fulfilling <4> The capacitor according to claim 1 . <6> In one cross section along the thickness direction of the substrate, At least one of the peripheral regions on one side and the other side sandwiching the central region corresponding to the width W1 has an area occupied by the fiber-shaped conductive member, the dielectric layer, and the conductor layer in the central region, which is a total area occupied ratio S 12 The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to 22 Including the high <1> ~ <5> 2. The capacitor according to claim 1 . <7> In one cross section along the thickness direction of the substrate, The peripheral regions on one side and the other side sandwiching the central region corresponding to the width W1 have a total area occupation ratio S of the fiber-shaped conductive member, the dielectric layer, and the conductor layer in the central region. 12The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to 22 Including the high <1> ~ <6> 2. The capacitor according to claim 1 . <8> In a plurality of cross sections along the thickness direction of the substrate, At least one of the peripheral regions on one side and the other side sandwiching the central region corresponding to the width W1 has an area occupied by the fiber-shaped conductive member, the dielectric layer, and the conductor layer in the central region, which is a total area occupied ratio S 12 The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to 22 Including the high <1> ~ <7> 2. The capacitor according to claim 1 . <9> In one cross section along an in-plane direction of the substrate, At least one of the peripheral regions on one side and the other side sandwiching the central region corresponding to the width W1 has an area occupied by the fiber-shaped conductive member, the dielectric layer, and the conductor layer in the central region, which is a total area occupied ratio S 13 The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to 23 Including the high <1> ~ <8> 2. The capacitor according to claim 1 . <10> The fibrous conductive member has a maximum height H max and the width W2 and the maximum height H max But the following relation: W2>H max Fulfilling <1> ~ <9> 2. The capacitor according to claim 1 . <11> The thickness of the dielectric layer is 10 nm or more. <1> ~ <10> 2. The capacitor according to claim 1 . <12> The average number density of the plurality of fibrous conductive members is 10 8 book / cm 2 That's all. <1> ~ <11> 2. The capacitor according to claim 1 . <13> The average length of the plurality of fibrous conductive members is 50 μm or more. <1> ~ <12> 2. The capacitor according to claim 1 . <14> The fiber-shaped conductive member is a carbon nanotube. <1> ~ <13> 2. The capacitor according to claim 1 . [Explanation of symbols]

[0209] 1, 1A capacitor 10 Substrate 10a surface 10b back side 10c side 20, 20A Composite Bulk Members 20a Outer edge 21 Fibrous conductive material (conductive fiber) 21a Part 1 21b Part 2 22 Dielectric layer 22a Dielectric part 23 Conductive layer 23a Conductor part 24 Space 30 Composite bulk members on the sides 100 Conventional Capacitor 110 Substrate 120 Composite Bulk Members 200 Forest 300 SiO2 Precipitation L1~L4: Sides showing the outline of the composite bulk member P1, P2 Left and right bottom of composite bulk member P3, P4 Left and right tops of composite bulk members P5, P6 Edge of outer edge P7, P8 End of first part C Center of the board R1 central area R2 outer area

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 a surface of the fibrous conductive member; a conductive layer covering a surface of the dielectric layer, a plurality of the fibrous conductive members, the dielectric layer, the conductor layer, and spaces formed between the plurality of the fibrous conductive members covered by the dielectric layer and the conductor layer constitute a composite bulk member; In a cross section along a thickness direction of the substrate, The composite bulk member has a width W on the opposite side to the substrate, the width direction being the in-plane direction of the substrate. １ and the width of the board side W ２ and the width W １ is the width W ２ Smaller, In at least one of the outer peripheral regions on one side and the other side of the composite bulk member sandwiching the central region corresponding to the width W 1 therebetween, The fibrous conductive member has a first portion extending parallel to an in-plane direction of the substrate.

2. In a cross section along a thickness direction of the substrate, The fibrous conductive member has a maximum height H ｍａｘ having Said width W １ , the width W ２ and the maximum height H ｍａｘ However, the following relationship exists: W ２ -W １ ≧1.6×H ｍａｘ The capacitor according to claim 1 ,

3. In a cross section along a thickness direction of the substrate, The composite bulk member has a width W ３ and width W ４ having Said width W ３ , the width W ４ and the maximum height H ｍａｘ However, the following relationship exists: W ３ ≧0.8×H ｍａｘ , and W ４ ≧0.8×H ｍａｘ The capacitor according to claim 2 ,

4. In a cross section along a thickness direction of the substrate, The fibrous conductive member has a maximum height H ｍａｘ having The length L of the first portion, and the maximum height H ｍａｘ However, the following relationship exists: L≧0.8×H ｍａｘ The capacitor according to any one of claims 1 to 3, which satisfies the above.

5. In one cross section along the thickness direction of the substrate, At least one of the peripheral regions on one side and the other side is a ratio S of the total area occupied by the fiber-shaped conductive member, the dielectric layer and the conductor layer in the central region. １２ The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to ２２ The capacitor according to claim 1 , further comprising a portion where

6. In one cross section along the thickness direction of the substrate, The outer peripheral regions on both sides have a total area occupation ratio S of the fiber-shaped conductive member, the dielectric layer, and the conductor layer in the central region. １２ The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to ２２ The capacitor according to claim 1 , further comprising a portion where

7. In a plurality of cross sections along the thickness direction of the substrate, At least one of the peripheral regions on one side and the other side is a ratio S of the total area occupied by the fiber-shaped conductive member, the dielectric layer and the conductor layer in the central region. １２ The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to ２２ The capacitor according to claim 1 , further comprising a portion where

8. In one cross section along an in-plane direction of the substrate, At least one of the peripheral regions on one side and the other side is a ratio S of the total area occupied by the fiber-shaped conductive member, the dielectric layer and the conductor layer in the central region. １３ The total area occupancy ratio S of the fibrous conductive member, the dielectric layer and the conductor layer compared to ２３ The capacitor according to claim 1 , further comprising a portion where

9. The fibrous conductive member has a maximum height H ｍａｘ and the width W ２ and the maximum height H ｍａｘ However, the following relationship exists: W ２ >H ｍａｘ The capacitor according to any one of claims 1 to 3, which satisfies the above.

10. The capacitor according to any one of claims 1 to 3, wherein the dielectric layer has a thickness of 10 nm or more.

11. The average number density of the plurality of fibrous conductive members is 10 ８ book / cm ２ The capacitor according to any one of claims 1 to 3.

12. The capacitor according to claim 11 , wherein the average length of the plurality of fibrous conductive members is 50 μm or more.

13. The capacitor according to any one of claims 1 to 3, wherein the fibrous conductive members are carbon nanotubes.

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