JP2007160483A - Wiring method for nanotube and electronic component and electron emission source using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring method by which wiring works are simultaneously operated even when there are a plurality of electrode pairs where nanotubes are to be laid, and the nanotubes can be individually controlled. <P>SOLUTION: A solvent 10 in which a plurality of nanotubes 11 are dispersed is dropped between electrodes 1, 2. Signal voltages 5, 6 in different waveforms having no correlation with each other are applied to the desired respective electrode pairs to be wired. The nanotubes 11 in the solvent are migrated by the signal voltages to wire between desired electrodes. The waveforms of the signal voltages applied are generated from an M-series (maximum length code) pseudorandom number bits sequence. When a current between the wired electrodes is detected, application of the signal voltage is stopped so as to lay one nanotube between each electrode pair. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for wiring nanotubes, an electronic component produced using this method, and an electron emission source.

  While the industrial application of carbon nanotubes is being studied, the method of wiring micron nanotubes has become a problem. For example, in order to create a microcircuit using nanotubes as conductive wires, it is necessary to wire (arrange) the nanotubes between desired electrodes. In response to this requirement, the following various technologies are currently proposed.

  As a first technique for arranging the nanotubes, there is an atomic force microscope. In this method, the nanotube is picked up and moved by the tip of a fine probe, and the nanotube can be arranged with an accuracy of about the size of the atom.

  As a second technique for arranging the nanotubes, there is a technique using lithography. In this technique, nanotubes are dispersed on electrodes to be wired, and only the nanotubes located between desired electrodes are fixed using a lithography technique. In this technique, even when there are a plurality of locations where wiring is desired, the wiring can be performed at the same time, which is efficient.

  As a third technique for arranging nanotubes, for example, there is an electrophoresis method disclosed in Patent Document 1. In this technique, a solvent in which nanotubes are dispersed in a colloidal form is dropped between electrodes, and an alternating voltage is applied between the electrodes to wire the nanotubes between the electrodes. According to this technique, it is possible to easily and reliably wire nanotubes.

  As an application of nanotubes, for example, Patent Document 2 proposes application to an electron emission source such as a field emission display (FED). Here, for example, paste-like nanotubes are applied onto a circuit by a printing technique to form a pattern. A part of the nanotube has an end protruding into the space from the substrate surface, and the open end of the nanotube serves as an electron emission source.

JP 2003-332266 A JP 2004-327208 A

  In the first technique, since the nanotubes are moved one by one, it takes a lot of time to perform a large number of wirings. In the second technique, the electrodes are usually wired by a large number of nanotubes, which is not suitable for applications where only one nanotube is desired to be wired. As the third technique, in the method described in Patent Document 1, one nanotube is wired for each pair of electrodes to which an AC voltage is applied. It is not possible to wire a plurality of nanotubes simultaneously to a plurality of electrode pairs. Have difficulty.

Further, when the nanotube is applied to an electron emission source, the following conditions are required.
(1) The height of the end of the nanotube is aligned.
(2) A plurality of protruding nanotubes must be independent of each other without being bundled together.
(3) There is no variation in the number of protruding nanotubes for each formed electron emission source.

  In the said patent document 2, the orientation carbon nanotube with which the direction and height of a carbon nanotube are equal is used. However, it is difficult to control each nanotube, and it is expected that it is difficult to meet the above conditions as an electron emission source.

  An object of the present invention is to provide an efficient method for wiring nanotubes in view of the above-mentioned problems of the respective technologies. That is, even when there are a plurality of electrode sets to be wired, a wiring operation is performed at the same time. A wiring method that can be controlled for each book is provided, and an electronic component and an electron emission source manufactured using the wiring method are provided.

  In the method for wiring nanotubes according to the present invention, a solvent in which a plurality of nanotubes are dispersed is dropped between electrodes, and signal voltages having different waveforms that are not correlated with each other are applied between desired electrodes to be wired. The inside nanotube is migrated and wired between desired electrodes. Preferably, the waveform of the applied signal voltage is generated from an M-sequence pseudo-random bit string. When the current flowing between the electrodes to be wired is detected, the application of the signal voltage is stopped, and one nanotube is wired between each electrode.

  An electronic component according to the present invention has a configuration in which nanotubes are wired between electrodes on a substrate, and a single nanotube is disposed between a plurality of sets of electrodes substantially parallel to each other.

  An electron emission source according to the present invention is configured to emit electrons from a plurality of nanotubes formed in connection with electrodes on a substrate, the plurality of nanotubes being arranged substantially in parallel to each other, and each nanotube from the substrate. The height to the tip of is substantially uniform.

  According to the present invention, when an electronic component using nanotubes is manufactured, the manufacturing efficiency and dimensional accuracy in the process of wiring the nanotubes are improved, thereby contributing to the performance improvement of the electronic components.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a nanotube wiring method according to the present invention, and is a diagram showing an overview of a nanotube solvent and a signal circuit configuration. In this embodiment, an electrophoresis method is adopted in which a solvent in which nanotubes are colloidally dispersed is dropped between electrodes, and a signal voltage is applied between the electrodes to wire the nanotubes between the electrodes.

  Reference numeral 11 denotes a nanotube, which is dispersed in a colloidal form in the solvent 10. Reference numerals 1a, 1b, 1c, 2a, 2b, and 2c denote electrodes. In this embodiment, the nanotube is divided into three sets of electrodes, that is, between the electrodes 1a and 2a, between the electrodes 1b and 2b, and between the electrodes 1c and 2c. It shall be wired to.

  As the voltage application circuit, three signal generation sources A (reference numeral 3a), B (reference numeral 3b), and C (reference numeral 3c) are used. Each signal generation source A, B, C generates a positive / negative signal (alternating voltage) having a predetermined voltage based on, for example, an M-sequence pseudo-random bit string. The M series (maximum length code) is a random number in which “0” and “1” are arranged at random, and is generated using, for example, a shift register and an exclusive OR (EXOR) gate. Here, the bit strings in the signal generation sources are not correlated with each other, and thus the generated signal waveforms are also uncorrelated. Reference numerals 5a, 5b, and 5c denote examples of waveforms of signals generated by the signal generation sources A, B, and C, which are applied to the electrodes 1a, 1b, and 1c, respectively. The inversion circuits A (4a), B (4b), and C (4c) are circuits that invert the polarities of the signal waveforms from the signal generation sources A, B, and C. Reference numerals 6a, 6b, and 6c show examples of signal waveforms after passing through the inverting circuits A, B, and C, and are applied to the electrodes 2a, 2b, and 2c, respectively.

  According to such a voltage application method, voltages having the same waveform and opposite polarities are applied to the electrodes 1a and 2a. A voltage having the same waveform and opposite polarity is also applied to the electrodes 1b and 2b. A voltage having the same waveform and opposite polarity is also applied to the electrodes 1c and 2c. That is, an electric field (alternating electric field) having a predetermined intensity is always generated between the electrodes 1a and 2a, between the electrodes 1b and 2b, and between the electrodes 1c and 2c. However, since there is no correlation between the voltages applied between the electrodes 1a, 1b, 1c or between the electrodes 2a, 2b, 2c, all electrodes (1b, 1c, 2b) other than the electrode 2a are viewed from the electrode 1a. The electric field between 2c) takes a small value when time averaged. The same applies to the electrodes 1b and 1c, and the electric fields between the electrodes 2b and 2c other than the electrodes 2b and 2c, respectively, become small values when time averaged.

  When subjected to the electric field as described above, the nanotubes 11 dispersed in the solvent 10 migrate between the electrodes where a strong electric field is generated. FIG. 2 is a diagram illustrating a state in which the nanotube 11 has migrated between the electrodes and wiring has been completed. That is, the nanotubes present in the vicinity of the electrodes migrate preferentially between the electrodes 1a and 2a having the strongest electric field, between the electrodes 1b and 2b, and between the electrodes 1c and 2c, and contact each electrode. At that time, the nanotube and the electrode are firmly attached by van der Waals force. In this way, the desired electrodes can be wired with the nanotubes.

  The fact that the electrodes are wired by the nanotubes can be detected as a current flowing between the electrodes. When it is detected that a desired electrode is wired, the voltage supply from the corresponding signal generation source is immediately stopped. In this way, the wiring operation is stopped when one nanotube is wired between desired electrodes. Further, even when nanotubes are migrating between electrodes that are not to be wired, the operation is stopped halfway to prevent wiring. When all desired electrodes are wired, the solvent 10 is washed away to finish the nanotube wiring.

  By the above operation, even when there are a plurality of electrode sets for which wiring is desired, the electrodes can be selected and the nanotubes can be wired simultaneously and one by one.

  1 and 2 show a case where a plurality of sets of electrodes for which wiring is desired are arranged substantially in parallel to each other, the present invention is not limited to this and may be non-parallel. Furthermore, the wiring may be performed by crossing three-dimensionally.

  Next, FIGS. 3 to 7 are views showing an embodiment of a process for manufacturing an electron emission source of a light emitting device (FED) using the nanotube wiring method of the present invention. In this embodiment, in order to use the nanotube as an electron emission source such as a cold cathode display, the nanotube is realized with a configuration in which one end of the nanotube is opened.

  FIG. 3 shows a step of wiring the nanotubes to the electrodes (first step). A plurality of sets of electrodes 1 and 2 are arranged in parallel on the substrate 20. Nanotubes are wired between the electrodes facing each other using the electrophoresis method and the signal voltage application method described in the first embodiment. As a result, the nanotubes 11 are wired on the substrate 20 approximately in parallel with each other at the same interval as the electrodes 1 and 2. At this time, the electric field can be concentrated by forming a shape having a sharp portion on the facing surface of the facing electrode, and the nanotube can be positioned and wired at the sharp portion of the electrode. As a result, the parallelism of the wired nanotubes is improved.

  FIG. 4 shows a step of forming a protective layer (second step). A protective layer 21 is formed on the entire surface of the substrate 20 on which the nanotubes 11 are wired, and the nanotubes 11 are strongly protected against subsequent processing steps.

  FIG. 5 shows a step of cutting the substrate 20 (third step). The intermediate position in the longitudinal direction of the wired nanotube 11 is cut with a diamond cutter or the like. If the substrate material is crystalline, a method of cleaving the substrate may be used. If necessary, the cut surface is polished to align the heights of the end portions of the nanotubes.

  FIG. 6 shows a step (fourth step) of projecting the end portion of the nanotube 11. First, the protective layer 21 is removed, then the end face 20a of the substrate 20 is removed by lithography or the like, and the tip end portion 11a of the nanotube 11 is projected (opened) out of the substrate 20. Further, a conductive material 12 such as aluminum is deposited between the electrodes 1 to connect the electrodes.

  FIG. 7 is a view showing an example of the structure of the electron emission source manufactured through the above-described steps. In the fourth step, a substrate 20 made of a plurality of nanotubes 11 connected to each electrode 1 is obtained. The electron emission source 40 has a structure in which the substrate 20 is a bottom surface and a gate electrode 31 is disposed in the vicinity thereof via an insulator 30. When a negative voltage is applied to the substrate 20 and a positive voltage is applied to the gate electrode 31, the electric field is concentrated on the nanotubes 11 disposed on the substrate 20, and when the applied voltage exceeds a predetermined value, electrons are emitted from the nanotubes 11. Released. The emitted electrons collide with a fluorescent screen (not shown) provided above to emit light. The insulator 30 serves to fix the interval between the nanotube 11 and the gate electrode 30.

  In the electron emission source of the present embodiment, the number of nanotubes used as the electron emission source can be kept constant by arranging one nanotube for each electrode. Each nanotube is not bundled but arranged one by one in parallel, and the height from the substrate to the tip of each nanotube can be made substantially uniform. Therefore, an ideal electron emission source for FED can be realized, which contributes to improvement in performance.

  Next, FIG. 8 is a diagram showing another example of the structure of an electron emission source manufactured using nanotubes. In this electron emission source 41, the substrate 20 obtained in the fourth step (FIG. 6) is inclined in a mountain shape, and the gate electrode 31 is arranged in the vicinity thereof via an insulator 30. As in the case of FIG. 7, when a negative voltage is applied to the substrate 20 and a positive voltage is applied to the gate electrode 31, the electric field concentrates on the nanotubes 11 arranged on the substrate 20, and the applied voltage is a predetermined value. The electron is emitted from the nanotube 11 when exceeding.

  According to this structure, by tilting the substrate 20 in a mountain shape, the distance from the tip of each nanotube 11 to the gate electrode 31 becomes substantially uniform. Therefore, there is an effect that the electron emission characteristics from each nanotube 11 can be made uniform regardless of the location (central portion and peripheral portion).

  In the above embodiment, when nanotubes are used as an electron emission source, the arrangement of a large number of nanotubes can be individually controlled and their characteristics can be made uniform, so that an excellent electron emission source for a cold cathode display such as an FED is provided. be able to. The method for wiring nanotubes according to the present invention is not limited to this, and can be applied to fine electronic circuits and sensors, and contributes to improvement in production efficiency and dimensional accuracy, and thus performance.

The figure which shows one Example of the wiring method of the nanotube by this invention. The figure which shows the state which completed the wiring by a nanotube. The figure which shows the 1st process of manufacturing an electron emission source using a nanotube. The figure which shows the 2nd process of manufacturing an electron emission source using a nanotube. The figure which shows the 3rd process of manufacturing an electron emission source using a nanotube. The figure which shows the 4th process of manufacturing an electron emission source using a nanotube. The figure which shows an example of the structure of the manufactured electron emission source. The figure which shows the other example of the structure of the manufactured electron emission source.

Explanation of symbols

1 (1a to 1c), 2 (2a to 2c) ... electrodes,
3a to 3c: Signal generation sources A, B, C,
4a to 4c: inversion circuits A, B, C,
5a-5c, 6a-6c ... signal waveforms,
10 ... solvent,
11 ... nanotubes,
20 ... substrate,
21 ... Protective layer,
30. Insulator,
31 ... Gate electrode,
40, 41 ... Electron emission source.

Claims (5)

In the nanotube wiring method of wiring nanotubes between a plurality of sets of electrodes,
A solvent in which a plurality of nanotubes are dispersed is dropped between the electrodes,
Apply signal voltages of different waveforms that are not correlated with each other between the wiring electrodes,
A method for wiring nanotubes, wherein the nanotubes in the solvent are migrated by the signal voltage and wired between the electrodes. The method of wiring a nanotube according to claim 1, wherein
The nanotube wiring method, wherein the waveform of the applied signal voltage is generated from an M-sequence pseudo-random bit string. The method of wiring a nanotube according to claim 1, wherein
When a current flowing between the electrodes to be wired is detected, the application of the signal voltage is stopped, and one nanotube is wired between the electrodes. In an electronic component configured to wire with nanotubes between electrodes on a substrate,
An electronic component comprising a plurality of sets of electrodes each having a single nanotube arranged substantially parallel to each other. In an electron emission source that emits electrons from a plurality of nanotubes formed in connection with an electrode on a substrate,
The electron emission source, wherein the plurality of nanotubes are arranged substantially parallel to each other, and the height from the substrate to the tip of the nanotube is substantially uniform.

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