JP2003081622A - Aggregate of carbon nanotube, and electronic element and electronic circuit obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of carbon nanotubes having new characteristics which have not been obtained heretofore by forming carbon nanotube aggregates on faces parallel to a substrate, and to provide a technique for utilizing the structure as a circuit constituting element. SOLUTION: The elment forming face in a substrate 101 consisting of single crystal silicon is provided with difference in level, and filmlike catalyst metals 102 are stuck to the sidewalls thereof. With the catalyst metals 102 as starting points, a plurality of carbon nanotubes are grown to a direction parallel to the substrate face (the direction horizontal to the substrate) to form carbon nanotube aggregates 103. The carbon nanotube aggregate 103 has a layer structure in which a plurality of carbon nanotubes are arranged at the inside of the substrate adjacently in a plurality of lines.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aggregate of carbon nanotubes, an electronic device and an electronic circuit using the aggregate.

[0002]

2. Description of the Related Art Carbon nanotubes have high mechanical strength,
It has excellent properties such as electrical conductivity and thermal conductivity, and its application to various fields is currently under consideration.

In order to use carbon nanotubes as a constituent material of an element, it is necessary to form a carbon nanotube structure on a substrate. As such a forming method, the following method has been conventionally used. Has been.

One is a method used for forming a cold cathode electron source of a field emission display (FED) or the like, in which catalytic ultrafine particles containing Fe, Co or Ni are attached to the surface of a substrate, and this is the starting point. This is a method for growing carbon nanotubes in the direction perpendicular to the substrate (Japanese Patent Laid-Open No. 11-139815, etc.).

On the other hand, the carbon nanotubes grown in the vapor phase are collected, dispersed in a solvent, applied on a substrate, and the solvent is removed to dispose the carbon nanotubes on the substrate surface. Is the way. According to this method, the carbon nanotubes arranged in layers in the direction parallel to the substrate can be obtained in a relatively simple process.

[0006]

By the way, in order to utilize carbon nanotubes as a constituent material of an electronic device and to apply them to an integrated circuit, a technique of forming an aggregate of carbon nanotubes in a plane parallel to a substrate. Is desired. However, there have been almost no studies in this direction. The present invention has been made in view of the above circumstances, and provides an aggregate of carbon nanotubes in a plane parallel to a substrate, and provides a carbon nanotube structure having novel properties that have not existed in the past. It is intended to provide a technique of utilizing a body as a circuit component.

[0007]

According to the present invention, there is provided an aggregate of carbon nanotubes provided on a surface of a substrate,
There is provided a carbon nanotube aggregate comprising a plurality of carbon nanotubes having an axis direction parallel to the surface of the substrate, and the plurality of carbon nanotubes having substantially the same axis direction.

Since this aggregate of carbon nanotubes is composed of a plurality of carbon nanotubes having an axial direction parallel to the surface of the substrate, it is suitable for use in forming an electronic element or an electronic circuit in the surface of the substrate. . Moreover,
Since a plurality of carbon nanotubes have substantially the same axis azimuth, a low resistance component is generated in the direction of the axis azimuth and a high resistance component is generated in the direction perpendicular to the axis azimuth in the plane of the substrate. A structure having characteristics is obtained.

Further, according to the present invention, there is provided an aggregate of carbon nanotubes provided on a substrate surface having a step,
There is provided a carbon nanotube aggregate which is composed of a plurality of carbon nanotubes grown in a direction parallel to a surface of a substrate with a side wall of the step as a starting point, and the plurality of carbon nanotubes have substantially the same axial orientation.

This carbon nanotube aggregate uses carbon nanotubes grown from the side wall of the step as a starting point. Therefore, it is possible to obtain a carbon nanotube aggregate in which the axial direction is aligned in the direction parallel to the substrate surface with good manufacturing stability. Further, by controlling the width of the step, the resistance value of the carbon nanotube aggregate can be controlled with high accuracy.

In the above-mentioned aggregate of carbon nanotubes, a plurality of carbon nanotubes may be arranged in layers within the surface of the substrate. By adopting such a configuration, a low resistance component in the axial direction,
A high resistance component is more clearly developed in the direction perpendicular to the axial direction in the substrate surface, and when this structure is used as an electronic device, good device characteristics can be obtained. Here, it is also possible to have a structure in which a plurality of carbon nanotubes arranged in layers are stacked in the direction perpendicular to the substrate.
Since the resistance between the carbon nanotubes stacked in the direction perpendicular to the substrate is relatively low, the adoption of such a configuration improves the degree of freedom of wiring when used as an electronic circuit.

According to the present invention, there is also provided an electronic device comprising the above-mentioned aggregate of carbon nanotubes. This electronic element has a structure that is advantageous for miniaturization and high integration of the element reflecting the characteristics of carbon nanotubes, and has suitable performance as an electronic element such as low power consumption. Further, it has a low resistance component in the axial direction of the carbon nanotube and a high resistance component in the direction perpendicular to the axial direction in the plane of the substrate, and can be suitably used as an element constituting an electronic circuit.

Further, according to the present invention, there is provided an electronic circuit characterized by using the above-mentioned carbon nanotube aggregate as a wiring or a resistor. As mentioned above,
Since this aggregate of carbon nanotubes has anisotropy in resistance value, it has a function as both a wiring and a resistor. Therefore, the wiring or the resistor can be used. In this electronic circuit, a plurality of carbon nanotube aggregates may be laminated with an insulating film interposed therebetween. By doing so, the wiring can stack the elements in the direction perpendicular to the substrate, and an advantageous structure can be realized by miniaturization and high integration of the elements.

Further, according to the present invention, there is provided a capacitive element characterized in that a pair of carbon nanotube aggregates are opposed to each other with a dielectric interposed therebetween. Since this capacitive element uses the aggregate of carbon nanotubes, it has excellent fine workability, and also has good strength and migration resistance. In this capacitive element, the pair of carbon nanotube aggregates may be composed of a plurality of carbon nanotubes having substantially the same axial orientation. By doing so, the performance stability of the capacitive element can be improved. Further, in this capacitive element, a pair of carbon nanotube aggregates may be provided on the surface of the substrate, and the plurality of carbon nanotubes may have an axial orientation parallel to the substrate surface. By doing so, the performance stability of the capacitive element can be further improved.

In the above capacitive element, the pair of carbon nanotube aggregates is provided on the surface of a substrate having a step, and is composed of a plurality of carbon nanotubes grown in parallel with the substrate surface starting from the side wall of the step. can do. By adopting such a configuration, it is possible to obtain a carbon nanotube aggregate having a uniform axial orientation in the direction parallel to the substrate surface with good manufacturing stability, and as a result, it is possible to further improve the performance stability of the capacitive element.

Further, according to the present invention, a step of forming a step on the element formation surface of the substrate, a step of adhering a catalytic metal to the side wall of the step, and a plurality of carbon nanotubes starting from the catalytic metal and parallel to the substrate surface. And a step of growing the carbon nanotubes in substantially the same direction.

According to this manufacturing method, it is possible to obtain a carbon nanotube aggregate having a uniform axial orientation in the direction parallel to the substrate surface with good manufacturing stability.

Further, according to the present invention, a step of providing a plurality of step-like steps on the element formation surface of the substrate, and a step of forming an insulating film on the surfaces of the plurality of steps so as to leave exposed portions on the step sidewalls. A step of adhering a catalytic metal to the exposed portion on the step side wall, and a plurality of carbon nanotubes starting from the catalytic metal and being grown in substantially the same direction in parallel with the substrate surface,
At this time, a carbon nanotube aggregate characterized by including a step of forming a void between the carbon nanotube formed on the insulating film and another carbon nanotube formed immediately below the carbon nanotube. A method of manufacturing the same is provided.

According to this manufacturing method, it is possible to stably form an aggregate of carbon nanotubes whose axial directions are aligned in a direction parallel to the substrate surface, and therefore a pair of aggregates of carbon nanotubes are opposed to each other via a dielectric. The arranged capacitive element can be manufactured with good manufacturing stability. Also, since the insulating film is used as a spacer,
By adjusting the film thickness, the spacing between the carbon nanotube aggregates can be controlled, and a capacitive element with a desired capacitance can be
It can be obtained with good manufacturing stability.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The carbon nanotube in the present invention means a material having a diameter of 1 μm or less and an elongated shape, and in particular, a material in which the hexagonal mesh surface of carbon is substantially parallel to the axis. Say. The carbon nanotube aggregate refers to a structure in which a plurality of carbon nanotubes are aggregated in a layer or a bundle. Here, if each carbon nanotube constituting the aggregate of carbon nanotubes has a structure having substantially the same axial orientation, the electrical anisotropy of each carbon nanotube is expressed as a macroscopic property, and a new novel A structure with characteristics is obtained.

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic configuration diagram of an electronic device comprising a carbon nanotube aggregate according to the present invention. A step is provided on the element formation surface of the substrate 101 made of single crystal silicon, and the film-shaped catalytic metal 102 is attached to the side wall of the step. Although silicon is used as the substrate material in the present embodiment, substrates of various semiconductors or insulators such as SiC, MgO, and quartz can be used.

Starting from the catalytic metal 102, a plurality of carbon nanotubes grow in a direction parallel to the substrate surface (horizontal direction of the substrate) to form a carbon nanotube aggregate 103. The carbon nanotube aggregate 103 is
It has a layered structure in which a plurality of carbon nanotubes are arranged adjacent to each other in a plurality of rows in the surface of the substrate. The carbon nanotubes may be single-wall nanotubes or multi-wall nanotubes, but from the viewpoint of strength and the like, multi-wall nanotubes are preferably used. In each carbon nanotube aggregate 103, only a single layer of carbon nanotubes is formed in the substrate vertical direction, and the height of the step is substantially equal to the diameter of the carbon nanotube.

The growth direction of each carbon nanotube forming the carbon nanotube aggregate 103 is the direction of the arrow shown in the figure. In this direction, the carbon nanotube aggregate 103 has a low resistance value and functions as a wiring. This is because each carbon nanotube has a low resistance value in the growth direction. On the other hand, in the direction perpendicular to the arrow in the drawing in the plane of the substrate, the resistance value of the carbon nanotube aggregate 103 is high, and the carbon nanotube aggregate 103 functions as a resistor. This is because the interface resistance between adjacent carbon nanotubes is relatively high.

A sectional view and a plan view of the electronic device shown in FIG. 1 are shown in FIG. FIG. 2A is a sectional view of an electronic device according to the present invention. The carbon nanotube aggregates 103 provided on the steps (terraces) of the substrate 101 grow in the horizontal direction of the substrate and are arranged so as to have overlapping portions with each other. The contact resistance of this overlapping portion is relatively low, and the resistance of each carbon nanotube aggregate 103 in the substrate vertical direction is also relatively low. Therefore, from the left end carbon nanotube aggregate 103 to the right end carbon nanotube aggregate 103 shown in the figure, they are electrically connected by a good conductor.

FIG. 2B is a top view of this element.
The resistance in the X direction and the direction perpendicular to the paper surface of the drawing is low, and the resistance in the Y direction is high. As a result, between-in the figure functions as a wiring, and between-functions as a resistor.

Next, a method of manufacturing the electronic device shown in FIGS. 1 and 2 will be described. First, as shown in FIG.
A multi-level step is provided stepwise on the element formation surface of No. 1. The height of each step is, for example, 5 to 300 nm. Such a step can be formed by using a normal photolithography technique, for example, by etching the surface of the substrate by an ion milling method. Next, a catalytic metal is vapor-deposited on the entire surface of the substrate under heating. The vapor deposition temperature is usually 200 to 600.
℃. When the catalyst is vapor-deposited under heating as described above, the catalyst metal migrates on the substrate plane and is selectively adhered to the step portion (FIG. 3B). The catalyst metal is not particularly limited as long as it serves as a catalyst for growth of carbon nanotubes, and examples thereof include iron (Fe) and cobalt (C
Those containing at least one of o) or nickel (Ni) are preferably used. An alloy such as a Fe—Ni alloy or a Ni—Co alloy may be used. Note that FIG.
In order to selectively attach the catalytic metal to the stepped portion as in (b), it is effective to appropriately adjust the vapor deposition temperature, the substrate material, the catalytic metal deposition method, and the like.

Next, carbon nanotubes are grown in the horizontal direction of the substrate by using the catalyst metal 102 as a growth starting point (FIG. 3C). For growth, film formation by a CVD method (chemical vapor deposition method) is preferably used. CVD
As a method, a plasma CVD method, a thermal CVD method, or the like can be used, but a plasma CVD method capable of growing carbon nanotubes at a relatively low temperature is preferably used. Source gases for growth by the CVD method include saturated hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, and cyclohexane; unsaturated hydrocarbons such as ethylene, acetylene, propylene, benzene, and toluene; Acetone, methanol,
Examples include raw materials containing oxygen such as ethanol, carbon monoxide, or carbon dioxide; raw materials containing nitrogen such as benzonitrile, and these may be used alone or in combination of two or more kinds. Hydrogen or helium, for example, can be used as the carrier gas flowing into the reactor together with the raw material gas, but the use thereof is not essential.

In FIG. 3C, the carbon nanotubes forming the carbon nanotube aggregate 103 have a structure in which they grow in the horizontal direction of the substrate. In order to obtain such a structure stably, the raw material gas It is effective to appropriately adopt a method of appropriately controlling the supply direction and the growth temperature of carbon nanotubes, or a method of growing carbon nanotubes while applying a magnetic field or an electric field.

As described above, an electronic element composed of the carbon nanotube aggregate 103 is formed. As described above, this electronic element also has a function as a resistor and a wiring. Carbon nanotube aggregate 10
By controlling the length of 3 and the height of the step, the resistance value of the resistor can be controlled to a desired value.

(Second Embodiment) An example in which the present invention is applied to a capacitive element will be described with reference to FIG. First, FIG.
As shown in (a), multi-steps are provided on the element formation surface of the substrate 101 made of single crystal silicon by an ion milling method or the like. Next, as shown in FIG. 4B, the insulating film 105 is formed on the entire surface of the substrate. The type of the insulating film 105 is not particularly limited, but an oxide film formed by a plasma CVD method, a thermal CVD method, an evaporation method, a sputtering method, a thermal oxidation method, or the like is used. In this embodiment, a silicon oxide film formed by the plasma CVD method is used.

Next, a film made of the catalytic metal 102 is formed on the portion of the step sidewall not covered with the insulating film 105. This film is formed in the same manner as described in the step of FIG. 3B in the first embodiment.

Then, using the catalytic metal 102 as a growth starting point, the carbon nanotube aggregate 103 is grown by the CVD method or the like. FIG. 4C is a diagram showing this state. An insulating film 105 is provided between the carbon nanotube aggregate 103a and the carbon nanotube aggregate 103b.
Intervenes as a spacer, and a void is formed by this film thickness. Depending on various conditions in the subsequent film forming process, the voids may be filled with a film material or may remain as voids and be filled with gas such as air. Further, the void may remain in a vacuum state.
In any case, the dielectric is arranged in this void portion and functions as a capacitance portion. As described above, according to the process of the present embodiment, the carbon nanotube aggregate 10
3a is a lower electrode, carbon nanotube aggregate 103b
Is formed as an upper electrode and air is used as a capacitance portion.

(Third Embodiment) The method of forming the resistance element and the capacitance element using the carbon nanotube has been described above. An electronic circuit using carbon nanotubes can be formed by combining these elements. In this embodiment, an RC circuit in which a resistance element and a capacitance element are combined is taken as an example to describe the structure and process.

FIG. 6 is a schematic configuration diagram of the electronic circuit according to the present embodiment. FIG. 6A is a sectional view of this element, and FIG. 6B is a top view. FIG. 6C is an equivalent circuit diagram of this element. As shown in FIGS. 6A and 6B,
There is a void between the carbon nanotube aggregate 103a and the carbon nanotube aggregate 103b, and these constitute a capacitive element. On the other hand, the carbon nanotube aggregate 103c is formed to extend in the vertical direction of FIG. 6B, that is, in the direction perpendicular to the carbon nanotube growth direction, and functions as a resistance element in this direction. An RC circuit is configured by these combinations.

Next, a method of forming the RC circuit of FIG. 6 will be described with reference to FIG. First, as shown in FIG. 5A, a plurality of steps are provided on the element formation surface of the substrate 101. At this time,
The width of each step in the direction parallel to the substrate surface is shown in FIG.
It corresponds to the structure shown in. That is, in FIG.
The bottom step where 03a is formed and the second step from the bottom where the carbon nanotube aggregate 103b is formed later are formed to have the same width. Further, the uppermost step on which the carbon nanotube aggregate 103c will be formed later is formed over a wider width than these.

After forming the step, the insulating film 105 is selectively formed on the second step from the bottom. The film thickness of the insulating film 105 is made lower than the height of the step so that the exposed portion of the step remains after the insulating film 105 is formed. Then, the catalytic metal is vapor-deposited under heating. At this time, the catalytic metal migrates on the plane of the substrate and selectively adheres to the step portion (FIG. 5).
(B)). Then, as shown in FIG.
The carbon nanotube aggregate 10 with 2 as a growth starting point
Grow 3 At this time, since the insulating film 105 is interposed between the carbon nanotube aggregate 103a and the carbon nanotube aggregate 103b, a void is formed, and as a result, a capacitive element is formed. Further, in the figure, a carbon nanotube aggregate 103c, which is wider than the carbon nanotube aggregates 103a and 103b, is formed in the uppermost step portion, and functions as a resistor. As described above, the RC circuit including the carbon nanotube aggregate 103 is formed.

(Fourth Embodiment) Next, an example in which the present invention is applied to a multilayer wiring structure will be described. FIG. 7 is a diagram showing an example of such an element. In this device, a lower device structure composed of 103a to c, 105a and the like and an upper device structure composed of 103d to f, 105b and the like are formed on a substrate 101 composed of single crystal silicon, and an interlayer insulating film is formed between them. Are formed. In the figure, a carbon nanotube aggregate 10
3a is a lower electrode, carbon nanotube aggregate 103b
Functions as an upper electrode and constitutes a capacitive element together with a void portion interposed therebetween. The carbon nanotube aggregate 103c formed on the upper portion functions as a wiring. A contact hole is provided in the upper part of the carbon nanotube aggregate 103c and is connected to the upper element structure. A carbon nanotube aggregate 103g is embedded in the contact hole to electrically connect the upper element structure and the lower element structure. The upper element structure is composed of a capacitive element including the carbon nanotube aggregate 103d and the carbon nanotube aggregate 103e, and a wiring including the carbon nanotube aggregate 103f.

In this embodiment, an example of a two-layer element structure has been shown, but an element structure in which these are laminated in three layers or four layers or more may be adopted. Further, in this embodiment, the carbon nanotube is used as the filling material of the contact hole,
For example, a metal such as tungsten or copper can be used.

Next, a method of forming the multilayer wiring structure shown in FIG. 7 will be described with reference to FIG. Up to FIG. 8A, the same steps as those shown in FIG. 4 are performed. Next, as shown in FIG. 8B, after forming an interlayer insulating film 107 on the entire surface, a contact hole 108 is provided in the interlayer insulating film 107. The interlayer insulating film 107 is, for example, a silicon oxide film or the like and is formed by CVD.
It can be formed by a method or the like. Contact hole 1
The layer 08 can be formed by using ordinary lithography technology and dry etching technology. Then, after depositing the catalytic metal 102 on the bottom of the contact hole 108, the carbon nanotube aggregate 103g is grown using this as a growth starting point. As a result, the state shown in FIG.

After that, similarly to FIG. 8A, the upper element structure is formed. As described above, the multilayer electronic device shown in FIG. 7 is formed.

(Fifth Embodiment) An example in which the present invention is applied to a differentiating circuit will be described with reference to FIG. In the present embodiment, the differentiating circuit shown in the equivalent circuit in the figure is configured by the carbon nanotube aggregate. Capacitance C of capacitance element
Was 1.8 × 10 ⁻¹² F, the resistance R of the resistor was 2 kΩ, and the time constant RC was 3.6 × 10 ⁻⁹ s.

The cross-sectional structure of the capacitance element is as shown in the figure. A pair of carbon nanotube aggregates having a thickness of 50 nm are laminated with an insulating layer having a thickness of 10 nm as a spacer, and this portion constitutes a capacitance element.

On the other hand, each carbon nanotube aggregate functions as a resistor. The outer dimensions of the aggregate of carbon nanotubes are as shown in the figure. The carbon nanotube growth direction is 50 micrometers, and the vertical direction is 5 micrometers.
The height is 50 nm in micrometers.
By forming the carbon nanotube aggregate according to this dimension, the differential circuit of the above design value is realized.

(Sixth Embodiment) In the present embodiment, FIG.
An example of a structure forming the circuit shown in FIG. In this embodiment, a carbon nanotube aggregate is formed in a stepped step having a different number of steps to form a circuit. The plane structure of the structure according to the present embodiment is shown in FIG.
It is shown in 0 (b). In FIG. 10A, in a region (AA ′), a capacitive element is formed near the insulating film forming portion, and a wiring and a resistor are formed above and below the capacitive element. On the other hand, the area (B-
In B '), the wiring is formed. These are connected in a step below the flat area in the center of the element (the uppermost flat area in the BB ′ cross-sectional view), which serves as a resistor. Figure 10
In (a), the direction from the left to the right corresponds to the growth direction of the carbon nanotubes and thus exhibits low resistance, and the direction perpendicular to this in the plane of the substrate exhibits high resistance.

In the figure, (1) to (3) are electrode forming portions, and when a voltage is applied between them (step voltage), they operate as a differentiating circuit between and (FIG. 11).

[0047]

As described above, the aggregate of carbon nanotubes according to the present invention is composed of a plurality of carbon nanotubes whose axial directions are aligned in the direction parallel to the substrate surface. It is preferably used to form an electronic circuit. In addition, a low resistance component appears in the direction of the axis direction and a high resistance component appears in the direction perpendicular to the axis direction in the plane of the substrate, so that an element having novel characteristics that has never been achieved is realized.

Further, in the method for producing a carbon nanotube aggregate according to the present invention, since the carbon nanotubes are grown starting from the side wall of the step, the carbon nanotube aggregate having a uniform axial orientation in the direction parallel to the substrate surface can be produced stably. You can get better. Further, by controlling the height of the step, the resistance value can be controlled with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an electronic device using a carbon nanotube aggregate according to the present invention.

FIG. 2 is a diagram showing an example of an electronic device using the carbon nanotube aggregate according to the present invention.

FIG. 3 is a diagram showing a method for manufacturing an electronic device using the carbon nanotube aggregate according to the present invention.

FIG. 4 is a diagram showing a method for manufacturing an electronic device using the carbon nanotube aggregate according to the present invention.

FIG. 5 is a diagram showing a method for manufacturing an electronic device using the carbon nanotube aggregate according to the present invention.

FIG. 6 is a diagram showing an example of an electronic circuit using the carbon nanotube aggregate according to the present invention.

FIG. 7 is a diagram showing an example of an electronic circuit using the carbon nanotube aggregate according to the present invention.

FIG. 8 is a diagram showing an example of an electronic circuit using a carbon nanotube aggregate according to the present invention.

FIG. 9 is a diagram showing an example of an electronic circuit using the carbon nanotube aggregate according to the present invention.

FIG. 10 is a diagram showing an example of an electronic circuit using the carbon nanotube aggregate according to the present invention.

11 is an equivalent circuit diagram of the structure shown in FIG.

[Explanation of symbols]

101 substrate, 102 metal catalyst, 103, 103
a, 103b, 103c, 103d, 103e, 103
f, 103g carbon nanotube aggregate, 105,
105a, 105b insulating film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/822 H01G 1/01 27/04 H01L 27/04 C 29/06 601 PF term (reference) 4G046 CA02 4G077 AA03 BA02 DB16 ED04 EE05 HA06 TK04 4K030 AA09 AA14 BA27 BB01 BB12 CA04 FA01 5E082 AB01 BC40 EE01 EE13 EE28 FF01 5F038 AC05 AC17 AR07 EZ20

Claims (12)

[Claims] 1. An aggregate of carbon nanotubes provided on a surface of a substrate, comprising a plurality of carbon nanotubes having an axial orientation parallel to the surface of the substrate, the plurality of carbon nanotubes having substantially the same axial orientation. An aggregate of carbon nanotubes having: 2. A carbon nanotube aggregate provided on a surface of a substrate having a step, the carbon nanotube being composed of a plurality of carbon nanotubes grown in a direction parallel to the substrate surface with a side wall of the step as a starting point. Have substantially the same axial orientation. 3. The carbon nanotube aggregate according to claim 1 or 2, wherein the plurality of carbon nanotubes are arranged in layers within a substrate surface. 4. The carbon nanotube aggregate according to claim 1, wherein the carbon nanotube aggregate has a structure in which a plurality of carbon nanotubes arranged in layers are stacked in a direction perpendicular to the substrate. . 5. An electronic device comprising the carbon nanotube aggregate according to any one of claims 1 to 4. 6. An electronic circuit using the carbon nanotube aggregate according to claim 1 as a wiring or a resistor. 7. The electronic circuit according to claim 6, wherein a plurality of the carbon nanotube aggregates are laminated with an insulating film interposed therebetween. 8. A capacitive element comprising a pair of carbon nanotube aggregates arranged to face each other with a dielectric interposed therebetween. 9. The capacitive element according to claim 8, wherein the pair of carbon nanotube aggregates is composed of a plurality of carbon nanotubes having axial directions in substantially the same direction. 10. The capacitive element according to claim 9,
The capacitive element, wherein the pair of carbon nanotube aggregates is provided on the surface of a substrate having a step, and is composed of a plurality of carbon nanotubes grown in a direction parallel to the surface of the substrate starting from a sidewall of the step. 11. A step of providing a step on an element formation surface of a substrate, and a step of adhering a catalytic metal to a side wall of the step.
And a step of growing a plurality of carbon nanotubes starting from the catalyst metal in substantially the same direction in parallel with the surface of the substrate. 12. A step of providing a plurality of step-like steps on an element formation surface of a substrate, a step of forming an insulating film on the surfaces of the step steps so as to leave exposed portions on the step sidewalls, and a step sidewall. A step of adhering a catalytic metal to the exposed portion, and a plurality of carbon nanotubes starting from the catalytic metal as a starting point are grown in substantially the same direction parallel to the substrate surface, and at this time, carbon nanotubes formed on the insulating film, And a step of forming a void portion between the carbon nanotubes and another carbon nanotube formed directly below the carbon nanotubes.