JP2003231097A - Structure mounting thin-film type particle having skeleton composed of carbon on substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure mounting a thin-film type particles having a skeleton composed of carbon on a substrate and to provide its manufacturing method. <P>SOLUTION: The thin-film type particles having the skeleton composed of the carbon are mounted on the substrate with improved affinity to the particles and the particle inside or the multiple particles are formed into patterns on the substrate. Their electrical features are changed according to their dimensions and shapes. This structure is a new system whose electronic properties and stability peculiar to the carbon substance having a periodic structure can be easily used and can be applied to a micro circuit (an element and wiring), a high-temperature circuit (the element and the wiring), a photoelectric transducer (a solar cell, a light emitter, etc.), a heating body, an optical element, and a stable recording material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which thin film particles having a skeleton made of carbon are placed on a substrate, a method for producing the same, and uses thereof.

[0002]

2. Description of the Related Art In recent years, the search for substances having high shape anisotropy and their applications have been rapidly progressing. As an anisotropic material having a carbon atom as a skeleton, one-dimensionally known graphite fibers and particularly thinned carbon nanotubes, and two-dimensionally known graphite, fluorinated graphite, graphite oxide, etc. ing. Of these, graphite, fluorinated graphite, and graphite oxide are all multilayer structures in which two-dimensional basic layers are stacked, and it is generally known that the number of layers is very large.
Furthermore, for graphite oxide, very thin ones with a small number of layers have been made (eg, NAKotov et al., Adv.M.
Ater., 8, 637 (1996)), the inventors of the present invention previously mentioned that it is desirable to call such graphite oxide (when the number of layers is one, for example, graphene oxide (graphene is the name of one layer of graphite)). ) And a graphite having a very small number of layers by reducing it (preferably called graphene when the number of layers is one). (Japanese Patent Application No. 2000-277307). Furthermore, the present inventors have obtained a particularly widespread thin film particle and a laminated aggregate in which thin film particles are laminated and expanded, and a reduced product thereof (Japanese Patent Application Nos. 2001-374537 and 20).
01-374538).

Here, the basic layer of graphite oxide is 1 carbon atom.
Carbon skeletons of one or two thicknesses (sp ³ carbon and sp ²
Consisting of carbon, sp ³ carbons and often), on both sides of the plane of the skeleton, such as acidic hydroxyl group is believed to have a structure bonded (e.g., T.Nakajima et al., Carbon, 26,357
(1988); M. Mermoux et al., Carbon, 29, 469 (1991)). When the thickness of the carbon skeleton is one carbon atom, hydroxyl groups are present on both sides of the carbon skeleton, and the amount of water between the layers is extremely small, the thickness of the basic layer is 0.61 nm. In addition, when the degree of oxidation is high and it is dried well, the oxygen contained in the oxidized graphite is 4
It is about 0 wt%.

The graphite oxide thin-film particles (hereinafter referred to as “oxidation-type thin-film particles”) are partially or completely reduced to be in an electronic state with many sp ² bonds similar to graphite, resulting in an electrical state. Higher conductivity. In particular, as a general behavior of graphite oxide, it is possible to form a graphite-like structure up to the inside of the multilayer by reduction by heating. It is known that an intermolecular force is generated between the particles to give a macroscopic shape such as an ordinary graphite film (J.Maire et al., Carbon, 6,555 (1968)). Oxidized thin film particles are reduced to thin film particles by the same heating (Japanese Patent Application No. 2000-277307).

Here, when the thin film particles are completely reduced, each basic layer of the thin film particles becomes a basic layer (graphene) of graphite. In the case of multi-layer particles, the interlayer distance substantially matches the interlayer distance of graphite, but the mutual positional relationship of the layers has a disordered structure that is more disturbed than that of graphite. Further, in the case of partial reduction, oxygen or the like remains in each basic layer, and the interlayer distance becomes larger than the interlayer distance of graphite.

The above-mentioned oxidized and reduced thin-film particles have a graphite oxide nanofilm (graphene oxide nanofilm if there is one layer) when the oxygen fraction is high, and a low oxygen fraction. When there is no oxygen, it can be called a graphite nanofilm (graphene nanofilm if there is one layer). Furthermore, as a unified approach, the oxidation type single-layer carbon nanofilm and multilayer carbon nanofilm, respectively,
It can be referred to as a reduced single-layer carbon nanofilm and a multi-layer carbon nanofilm. With the name of this carbon nanofilm, although it is a disordered layer as described above, there is no confusion caused by calling it graphite.

For a thin carbonaceous material having a thickness similar to those of these thin film particles, it is possible to form it on the substrate by vapor deposition or to thermally decompose the organic substances placed on the substrate (further called a crystal called graphitization). It is also possible to form it by growing it. However, even if the carbonaceous material has relatively high crystallinity, it has a structure in which small crystals are gathered in a wide area. Further, the formation thereof requires conditions such as high temperature and vacuum.

[0008]

Various applications such as electronic physical properties are expected for the oxidized or reduced thin film particles (carbon nanofilm). For example, fine circuits (elements and conductors), high temperature circuits (the same), photoelectric conversion elements (solar cells,
Light emitting elements), heating elements, optical elements, stable recording materials, etc. are considered. Circuits for high temperatures are currently in the following situations.

In recent years, research on devices (electronic devices, optical devices) using semiconductors having a wide band gap such as diamond and silicon carbide has been advanced. This device is expected to operate at high speed, high power, high temperature up to about 500 ° C., high radiation, and generate ultraviolet light (for example, Hiroshi Kawarada, Applied Physics, 67,128 (1999)). At present, individual devices are being manufactured, but it is expected that they will eventually be integrated into a circuit.

It has been considered to use a metal, graphite and its analogs (a carbonaceous substance mainly composed of sp ² ), a semiconductor doped with a high concentration of impurities, etc. in the conductor portion of such a device. Of these, a suitable level of conductivity, little deterioration (oxidation, etc.) due to high temperatures during device manufacturing (especially pattern formation many times) and during use (especially for a long time), and semiconductor part Considering the high affinity,
In particular, graphite and its analogs may be desirable. As an example, regarding a method of graphitizing a part of diamond, irradiation of protons and the like (Patent 2834829), ion implantation and heating (JP-A-07-37835), irradiation of electron beam and laser (JP-A-10-261712) and so on. Further, a method of graphitizing an organic substance patterned on diamond is also considered. However, these methods have problems such as poor position selectivity and deterioration of the semiconductor portion due to the need for heating at a high temperature for a long time.

As a method for hydrophilizing a semiconductor material having such a wide band gap, for example, for a diamond substrate, oxygen plasma irradiation or a method of contacting an aqueous solution of hydrogen peroxide to irradiate ultraviolet light (Japanese Patent Application Laid-Open No. 10-1731).
4. The contact angle with water changes from 90 degrees to 40 degrees before and after the treatment). Regarding silicon carbide, a method of making hydrophilic at the same time when forming a film (Patent 29
23275) and the like are considered.

In various applications as described above, in order to stably use the electronic properties of the thin film particles for a long period of time, one or a plurality of thin film particles are placed on the substrate with good adhesion and various desired dimensions are obtained. Need to be processed into a shape. Further, when electricity is applied to the processed thin film particles, it is necessary to connect to an external electric circuit or the like. However, no concrete method for them has been proposed.

An object of the present invention is to propose application targets such as various devices and conductors utilizing the electronic properties of thin-film particles (carbon nanofilm), and at the same time, to manufacture those targets as a structure including a substrate. To provide a concrete and simple method for

[0014]

In order to achieve the above-mentioned object, the present inventors have two methods of improving the affinity of the substrate for the thin film particles and arranging the thin film particles by position-selective processing.
The present inventors have completed the present invention concerning the use of thin film particles on a substrate by studying the elemental technologies to be summarized in one and finding an object that can effectively utilize the characteristics of the thin film particles and a method for producing the same.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (Synthesis of Oxidizing Thin Film Particles) The oxidizing thin film particles (oxidizing carbon nanofilm) used in the present invention are as disclosed in Japanese Patent Application No. 2000-277307. , Graphite with few impurities and high crystallinity with a well-developed layer structure is subjected to chemical or electrochemical oxidation, and purification is performed to remove even smaller ions as much as possible, and spontaneous separation of layers Use the one advanced. If the decomposition (destruction) of the skeleton of each layer is small, the oxidation time is to promote the separation of layers as much as possible,
The length in the plane direction (direction in the plane formed by the a-axis and the b-axis of the raw material graphite) is preferably as long as 30 minutes or more per 10 μm.
However, conversely, if the layers can be separated, the oxidation may be completed in such a shortest time.

In particular, when synthesizing large thin film particles in the plane direction, as disclosed in Japanese Patent Application No. 2001-374537, the length in the plane direction is as wide as 1 mm or more, and the thickness is large. (Length in c-axis direction) is, for example, 300μ
Decomposition (destruction) of each layer by using graphite with high crystallinity as thin as m or less as raw material for long-term oxidation and agitating the liquid during synthesis (oxidation and purification) to a minimum Should be suppressed. Further, in order to obtain thin film particles having a desired shape (square or the like), the shape of raw material graphite may be processed in advance.

Further, as a method for particularly promoting the separation of layers, there is a method of heating a dispersion liquid of thin film particles at around 100 ° C.

As described above, a dispersion liquid in which extremely thin thin film particles are dispersed in water, which can be called an oxidation type carbon nanofilm, is synthesized.

The size of the thin-film particles is such that the thickness (the direction of the c-axis in the raw material graphite) is 0.4 nm as a relatively small particle.
10 nm, preferably 0.4 nm to 5 nm, and the size in the plane direction (direction of a-axis and b-axis in raw graphite) is 2
It is 0 nm or more, preferably 200 nm or more, and more preferably 1 μm or more. In the case of a large size, the thickness is, for example, 0.4 nm to 10 μm (especially in the case of being thick, it is included in the nanofilm in consideration of thinning it in later processing), preferably 0.4 nm to 1 μm, The size in the plane direction is 500 μm or more, preferably 3 mm or more. This size may be selected depending on the application of the thin film particles.

When the synthesis of the thin film particles is completed, the thin film particles are in the form of a dispersion liquid containing water as a dispersion medium. It is possible to replace the dispersion medium of this dispersion liquid with water, instead of water, with a highly polar liquid having a relative dielectric constant of about 15 or more, such as methanol, ethanol, acetone, or 2-butanone. As a means for using such a high-polarity liquid other than water as the main dispersion medium, a method of diluting by adding a sufficiently high-polarity dispersion medium other than water contained in the original dispersion liquid, There is a method in which a high-polarity dispersion medium other than water is added and then the supernatant is repeatedly removed by centrifugation and decantation to gradually exchange the high-polarity dispersion medium other than water.

The thin film particles have high lyophilicity (dispersibility etc.) with respect to a highly polar dispersion medium including water. However, the lower the concentration of the thin-film particles, and the lower the dielectric constant of the dispersion medium when comparing a plurality of different dispersion media, the gravity (rather than centrifugal force can be substituted instead of the effect of electrostatic repulsion). ), The thin film particles tend to settle. Also, the larger the thin-film particles, the more they tend to settle. However, the case in which such particles having a tendency to settle out is also referred to as a dispersion liquid.

Since the dispersion liquid of thin film particles has a high anisotropy of the shape of the thin film particles, the change in fluidity due to the concentration is large. Although depending on the size and shape of the thin film particles contained, the dispersion liquid having a concentration of, for example, about 2 wt% does not flow even when the container is tilted. (Synthesis of layered aggregates of oxidized thin film particles)

As previously disclosed in Japanese Patent Application No. 2001-374538, the thin-film particles are allowed to settle by allowing the above-mentioned dispersion liquid of the thin-film particles to settle to form a bond between a plurality of thin-film particles. By doing so, it is also possible to synthesize a laminated assembly of thin film particles. The resulting bond may be a covalent bond due to intermolecular force, hydrogen bond, dehydration between particles, or the like. The period in which the dispersion liquid is allowed to stand is 10 days or longer, preferably 30 days or longer if it is allowed to settle by gravity alone. Further, if the sedimentation is performed by centrifugal force, the subsequent standing may be for a shorter period. The concentration of the thin film particles in the dispersion liquid to be precipitated depends on the size of the thin film particles to be used, but is preferably about 0.1 wt% or less, more preferably 0.01% by weight or less.
It is less than wt%. When the sedimentation is fast or the concentration is high, the particles are in contact with each other before they are sedimented, so that it is difficult to perform a clean stacking, and the aggregate becomes disturbed. Further, when the concentration is low, particles do not overlap to each other to give sufficient strength, and a wide aggregate cannot be obtained.

This laminated assembly can float in the liquid when it is gently shaken, and can exist in the liquid in an isolated state. The size depends on the size of the original thin film particles, but the thickness is 10 nm or more, the size in the plane direction is 100 nm or more, and further 100 μm or more.
Further, since this laminated aggregate has a large spread with respect to the thickness, it can be bent sharply to be broken even though it is composed of thin-film particles containing a dense carbon skeleton. In the bent portion, the individual thin film particles, which are the constituent elements, also bend sharply so as to be broken. Further, in this portion, each basic layer of thin film particles, which can be said to be a large planar molecule, is also sharply bent.

This laminated aggregate is also a carbon nanofilm in a broad sense, but since it has a secondary structure, it will be treated separately below and explicitly referred to as a laminated aggregate of thin film particles.

(Synthesis of Reducing Thin-Film Particles) Various known reduction reactions using a reducing agent and electrode reactions (electrolytic reduction) can be used to reduce the oxidizing thin-film particles. However, especially when a reducing agent is used, complete reduction to the inside of the multilayer particles is considered difficult unless the basic layer is decomposed. On the other hand, reduction by heating, which is known as the general behavior of graphite oxide (J.Maire et al., Carbon,
6,555 (1968)), it is possible to reduce almost completely to the inside of multiple layers. Oxidized thin-film particles were previously described in Japanese Patent Application 2
As disclosed in 000-277307, reduction type thin film particles are formed by similar heating.

Here, when the thin film particles are completely reduced, each basic layer of the thin film particles becomes a basic layer (graphene) of graphite. Interlayer distance (undefined for single layer)
Is almost the same as the interlayer distance of graphite, but the mutual positional relationship of the layers is a disordered structure that is a little more disturbed than that of graphite. In addition, the mutual positional relationship in the plane direction of the plurality of thin film particles has a very disordered (almost random) disordered layer structure, and further, there is a gap between the plurality of particles.

On the other hand, the degree of reduction of the thin film particles does not necessarily have to be perfect, and partial reduction may be used as long as electronic properties and the like can be stably utilized. In this case, each basic layer contains oxygen and the like, and its interlayer distance is larger than that of graphite.

The reduction by heating is particularly performed at 150 ° C to 200 ° C.
It rapidly occurs at around ℃, and further slowly progresses to 1000 ℃ or more in a non-oxidizing atmosphere or in vacuum. Further, it is expected that a larger crystal will be formed by pressing at a higher temperature. On the other hand, since it burns down in air at 600 ° C. or lower, only partial reduction in which oxygen or the like remains is possible. During the reduction by heating, desorption of water, oxygen, carbon compounds, etc. occurs. As a result, the oxygen fraction changes from about 40 wt% before reduction to about 0 to 35 wt%.

Oxygen and the like are desorbed by the reduction, so that the thickness of the thin film particles is reduced. On the other hand, the size of the thin film particles in the plane direction does not change much. This is sp
Closest of carbon in making a ² carbon plane skeleton (corresponding to graphene) - the distance between the carbon 0.142Nm, taken out flat skeleton zigzag making the sp ³ carbon (cubic diamond (111) surface by one surface The closest carbon-carbon distance in (111)
It can be understood that the distance projected on the plane is 0.145 nm, and the same distance when both carbons of sp ³ and sp ² are included is between them. Due to the small change, peeling is less likely to occur in the reduction on the substrate described later.

As described above, by heating at a relatively low temperature,
Oxidized thin film particles (oxidized carbon nanofilm)
From this, reduced thin film particles (reduced carbon nanofilm) are synthesized. Further, in the same manner, a laminated aggregate of reduced thin film particles is synthesized from a laminated aggregate of oxidized thin film particles.

(Structural Characteristics of Thin-Film Particles) The thin-film particles synthesized as described above have a highly periodic carbon skeleton in each layer, and in particular, reduced-type thin-film particles have pi-electrons in the skeleton. There are many structures. Therefore, it is possible to develop electronically. In particular, when utilizing the novel electronic properties (described below) that are manifested in the fine structure of carbon-based materials, a structure such as reduced thin-film particles with high periodicity and a wide carbon skeleton is optimal. Is. Further, particularly, the oxidative thin film particles have polar functional groups and are lyophilic to many liquids. Therefore, a thin structure of a carbon-based material, which is usually difficult to handle, can be easily handled in the form of a dispersion liquid.

(Electronic Characteristics of Thin Film Particles) The advantage of comparing the thin film particles (carbon nanofilm) with carbon nanotubes, which is expected as an electronic nanomaterial, is two-dimensional. Is capable of collectively arranging complicated wiring and elements consisting of many parts that spread three-dimensionally in post processing (many nanotubes need to be individually arranged), and the contact area with external electrodes can be set arbitrarily Possible (nanotube has a small contact area and may have high resistance), line width can be set arbitrarily at the time of processing (nanotube needs to be selected by thickness, especially thick line can be supported by multiple lines) Will be), and so on. However,
Carbon nanotubes and carbon nanofilms are not exclusive, and by combining them, or by combining other materials, more novel uses become possible.

(Change due to miniaturization) In electron conduction in a solid, when the size of the solid becomes fine, ballistic conduction (electrons move without scattering for an appropriate distance), quantum interference effect (electron wave) Changes in conductivity due to the phase difference of), quantum size effect (energy level is discretized by confinement of electrons, and band state of electrons can be controlled by material and size). Such a change can be generated by fine processing of the reduced type thin film particles. Here, for example, the quantum size effect occurs when the size of a substance becomes equal to or smaller than the wavelength of an electron wave. The observation of the quantum size effect up to now is that the electron wavelength is 1 nm.
It has been performed on various semiconductors whose electron wavelength is several tens of nm or more and which is easy to process, rather than metals which are relatively small and relatively difficult to process. On the other hand, the reduced type thin film particles may exhibit a quantum size effect with a large size (particularly a size in the plane direction) even though the reduced type thin film-like particle is a substance having relatively high conductivity.

On the other hand, the reduction-type multilayer thin-film particles have a particularly low conductivity in the interlayer direction as compared with the planar direction (in-layer direction). Therefore, the effect of thickness on electrical properties is generally low, except when it is fairly thin (less than 10 nm, for example),
It may be treated as if the electrically independent layers overlap.
Therefore, it is possible to use various changes due to miniaturization in the plane direction and at the same time secure the amount of current with an appropriate thickness (number of layers).

(Use of semiconductor property, etc.) It is known that the conductivity of graphite oxide is increased by several orders of magnitude by heat reduction (J.
Maire et al., Carbon, 6,555 (1968), particle thickness is unknown in this document, but not so thin). Oxidized thin film particles also undergo a similar change. Such a change from the semiconductor region to the good conductor region occurs when the OH group and the like are desorbed by heating and at the same time, the ratio of sp ² carbon in the carbon skeleton increases. This change can be controlled by temperature, but O
On the contrary, since the structure including the H group has low stability, it is easily affected by heat. Therefore, it is not desirable to use this semiconductor region as it is in electronic circuits and devices that require long-term reliability. On the other hand, a method of stabilizing the semiconductor region (more generally, a method of changing electrical properties,
Further, as a method of expressing a peculiar property in the fine structure as a special case of the change, use of the following chemical change, use of external influence, use of shape processing, and the like can be considered.

Stabilization of a semiconductor region by a chemical change such as modification or modification (further, a method of changing electrical properties) is
By introducing a stable structure for making some of the many carbons in the carbon skeleton into sp ³ carbons (since all sp ³ makes a non-conductor, sp ² and sp ³ are introduced so that they coexist) It will be possible. Hydrogen (partial hydrogenation, partial hydrogenation, as a light element that can be introduced in a liquid phase or gas phase chemical reaction for stabilization)
It may be a p-type semiconductor), fluorine (partially fluorinated, the same), and the like. Here, in order to introduce the device selectively for the production of the device, it is possible to place it on the substrate and use a mask together (resist work or the like). Further, if the carbon skeleton is allowed to be partially changed, a method of position-selective introduction also includes irradiation (implantation) of an ion beam or a neutral particle beam. As a result, it is possible to remove a part of carbon (make it finely porous) and to introduce a hetero atom such as boron or nitrogen (possibly increasing the number of carriers). Further, if the raw material is not limited to graphite, it may be possible to prepare thin-film particles from a carbon-based multilayer structure substance containing heteroatoms (boron, nitrogen, etc.).

Stabilization of the semiconductor region by utilizing the influence from the outside (further, a method of changing the electric property) is possible by utilizing the change of the electric property of the thin film particles by the substrate. For example, the use of a substrate having a high electron donating or accepting property, such as a high dielectric substance, in particular, a polarized electret, is expected to have an effect of generating carriers similar to chemical doping. In addition, the use of the electric field effect described below can be considered.

Stabilization of the semiconductor region by shape processing (further, a method of exhibiting a characteristic peculiar to the fine structure) can be achieved mainly by finely processing the thin-film particles after complete reduction. For this, the recent research results of various condensed carbon ring substances can be used. When these carbonaceous materials are shown in order from narrow ones to wide ones, they are linear (one-dimensional: polyacetylene), strip-shaped (1.5-dimensional: polyacene group in a broad sense (polyacene series, polyphenanthrene series, etc.), The wider one is called a nanoribbon),
It becomes planar (two-dimensional: graphite (graphene in one layer)). In these carbon-based materials, it is predicted that the band gap will become smaller as the width becomes wider, and the band gap will change depending on the orientation of the carbon skeleton (eg, K. Tanaka et al., Synthetic Metals, 17,143). (198
7), however, this prediction is for the structure of hydrocarbon-based, ie hydrogen-terminated carbon-based materials). In the case of a planar carbon-based material, the effect of the number of layers and the stacking state is
When one layer of graphene (predicted to be a semiconductor with a band gap of 0) is regularly stacked (graphite), conductivity appears (in the case of several layers, it changes stepwise).
When a large number of layers are randomly stacked (turbulent structure carbon), it is expected to be a semiconductor with a band gap of zero. As described above, in the band-shaped structure, it is possible that the electrical properties centered on the semiconductor property can be arbitrarily controlled by the width, the thickness (the number of layers), the orientation of the carbon skeleton, the stacking state, the type of termination bond, and the like. is there. Note that this possibility is not limited to thin-film particles after complete reduction, but is common to large, highly cyclic carbon-condensed ring materials, and generally does not depend on the production method ( It does not have to go through oxidized thin film particles).

Based on thin-film particles (especially single-crystal particles having a large area), it is easy to simultaneously manufacture a large number of structures whose electric properties can be arbitrarily controlled by fine processing. , Regioselectively completely removes carbon,
Alternatively, by making it thin, it is possible to make a desired circuit or device. In addition, it is necessary to use multiple wires to increase the amount of current in a structure with a narrow width (however, there is a possibility that a vibration phenomenon will occur if a loop is created), or to make a serpentine to increase the resistance and to periodically It is also possible to make holes.

As described above, it is possible to extremely easily form a 1.5-dimensional arbitrary structure in the plane direction, such as a thin film-like particle (carbon nanofilm). Sexual carbon structures have heretofore been unknown. Also, no specific processing policy was proposed.

(Improvement of conductivity) The reduction type thin-film particles (reduction type carbon nanofilm) have characteristics of conductivity like carriers (electrons and holes) like those of general molecular substances.
Has a relatively low density (number per unit volume), and the conductivity between the layers corresponding to the molecules or between the particles is lower than the conductivity inside the layers corresponding to the molecules. .
Therefore, when it is desired to increase the conductivity, it is desirable to increase the carrier concentration or to increase the conductivity between layers or between particles.

As a method for increasing the carrier concentration, first, there has been known chemical doping for a long time. However, in this case, the resulting intercalation compound is generally unstable in air, and stable use for a long period of time is difficult. Furthermore, a method called field effect doping, in which a charge is generated in an insulator part adjacent to a part to be highly conductive and the charge is injected as a carrier to the part to be highly conductive (for example, A.Tsumura et al., Appl. .Phys.Lett., 49,1210 (198
6)), and there are some examples of using this method to make aggregates (crystals, etc.) of molecular substances into a highly conductive state (a superconducting state at low temperatures) (eg JHSchon et al., Science, 2).
88,656 (2000)). In this case, another part for generating charges is required, but stable use for a long period of time is possible.
When used in the semiconductor region, it can be changed to either n-type (electrons are carriers) or p-type (holes are carriers). By using this method for reducing thin-film particles, it is expected that the superconducting state will be exhibited in the low temperature region and the conductivity will be improved (and superconductivity) in the normal temperature region. The reduction type thin film particles are suitable for graphite-based field effect doping because of high periodicity of each layer, high shape and high adhesion to a substrate.

In order to enhance the conductivity between layers or between particles (relatively reduce the influence of conductivity between layers or particles),
It is important to use as large a particle as possible, or to use a small number of particles so as not to cause a problem between particles, and in the case of a large number of particles, to stack them neatly with a small gap. In order to further increase the conductivity, sigma bond and pi bond are generated between the layers of different particles at the same position in the thickness direction, and the layers that are overlapped with each other to the extent that the conductivity inside the layers is not significantly lowered are provided. It is possible to break it down a little to form sigma bond and pi bond between layers.
For the formation of these bonds, high temperature heating or current application in a non-oxidizing atmosphere, irradiation with ultraviolet light or particle beam, etc. can be used.

(Application to electronic circuits and devices) Oxidizing type and reducing type thin film particles (single particle or plural particles)
The target of application to electronic circuits and devices can be broadly classified into two types, one for large circuits and one for fine circuits. In addition, the mode of use of the thin film particles can be roughly classified into two types: single or a few large thin film particles and a very large number of fine thin film particles. These combinations are as follows.

For large-scale circuits, there are conductor parts of high-temperature semiconductor devices (semiconductor parts are diamond, silicon carbide, etc.) which are expected to develop in the future. Such devices are expected to have high temperature resistance (up to about 500 ° C.), high output, radiation resistance, and high-speed calculation in the future, and some of the ultraviolet light emitting elements have been realized. . In this application, it is considered that the conductor portion has a relatively wide line width of 1 μm or more or 1 mm or more, and a large area has a large area of several cm ² or more. The thin film particles suitable for this application may be used alone or in a small number of large thin film particles, or in a very large number of fine thin film particles. Among them, when an extremely large number of fine thin film particles are used, it is possible to form a conductor portion in a large area or a long portion with macroscopically low anisotropy. However, it is necessary to pay attention to the fact that there is no wide continuous layer and the presence of voids has relatively low conductivity, and the thickness varies depending on the position.

For fine circuits, there are especially element bodies and conductors of high-speed or special devices which are expected to develop in the future. Such devices are expected to have ultra-high-speed operation, high integration, and quantum calculation (multiplex operation capable of solving combination problems at high speed). In this application, an element body or a conductor portion having a narrow line width of 1 μm or less or 10 nm or less is important, and at the same time, a wide line width is required for a connection portion with the outside. In addition, discontinuous layers, voids, and variations in thickness due to position (excluding changes in the thickness given by processing) are not desirable in the element body or conductor portion with a narrow line width, which is responsible for the function. A layer of connected, continuous carbon skeletons is required. Furthermore, as large an area as possible is desirable for integrated circuits and mass production.
As a result, the morphology of thin film particles suitable for this application is
Mainly, it is a single or a small number of large thin film particles. However, due to the anisotropy of the carbon skeleton, there is some restriction in the direction of use (for example, when making a thin strip, the electrical conductivity changes depending on the orientation of the skeleton).

As described above, by using the thin film particles and combining another insulator, semiconductor, and good conductor,
Transistors (especially fine ones for single electrons),
It is possible to fabricate individual elements such as resistors and capacitors and wiring portions, and it is also possible to fabricate integrated circuits thereof.

Even if the thin-film particles are completely reduced, the conductivity is lower than that of copper, for example, unless the above-mentioned field effect doping is performed, and when a large number of particles are used, the influence of boundaries is also added. , Long conductors have high resistance.
Therefore, it is desirable to limit the use of the circuit using the thin film particles as described above to a part where the temperature becomes high or the speed becomes high. However, contrary to metals, the conductivity increases at high temperatures and is stable at higher temperatures, so it is suitable for high temperatures.

The thin film particles have a lower conductivity in the thickness direction than in the plane direction. Therefore, for electronic circuits and devices using thin-film particles, it is desirable to perform shape design for anisotropic substances, such as securing a current amount in the thickness direction by using a large area portion for each important point. .

(Use of Substrate and Improvement of Affinity) In order to obtain reproducibility of electric properties in various uses of thin film particles as described above, it is necessary to determine the size and shape in the plane direction for processing. There is. Since it is difficult or unreliable to suspend thin film particles in the space stably for a long period of time during processing or when actually using it in a device, etc., in combination with other specific types of substances. Therefore, the thin film particles are placed on a suitable substrate of another substance or are held inside the matrix of another substance. Of these, the method of mounting on the substrate is particularly important.

As the type of substrate, various known substances can be used, but the possibilities are expanded by combining substances having different properties (electrical properties, optical properties, etc.) with the thin film particles. In addition, depending on the requirements such as need to be reduced by heating and use at high temperature depending on the application, a substrate from an insulator to a semiconductor, and further a substrate with stable heat resistance of about 300 ° C. or more are required. desirable. The materials are inorganic materials such as silica, alumina (sapphire), silicon, diamond, silicon carbide,
Borosilicate glass, aluminosilicate glass (non-alkali glass), organic materials such as epoxy resin, polyimide and various heat-resistant resins. Also, a substrate that has been subjected to various known treatments such as impurity doping in semiconductor applications,
It may be a composite substrate such as a fiber reinforced resin, or a multilayer substrate in which a thin insulator is placed on a substrate made of other material such as metal. Further, a stretchable substrate or a porous substrate capable of changing the electrical properties of the thin film particles, a substrate having fine irregularities, or the like may be used.

The substrate is usually easy to handle, but may be three-dimensional. In any case, for example, by treating thin film particles with the dispersion,
Pattern formation is possible as described later.

When the thin film particles are placed on the substrate, it is easy to use the oxidized thin film particles. In this case, it is desirable to improve the affinity of the substrate in advance before placing the thin film particles in order to stably adhere the thin film particles to the substrate, including during use after processing. This corresponds to increasing the polarity of the substrate surface and can be realized by increasing the density of functional groups on the substrate surface.

Specific methods for improving the affinity include chemical treatment using acid or alkali, physical treatment using heat, plasma, various beams, and the like. In particular, as long as the present inventors have tried various inorganic substrates, simple heat treatment at about 300 ° C. or higher was effective. It was also desirable to wash as much as possible before the heating and soak in water after the heating. This is considered to be the effect of removing organic substances attached to the surface and generating oxides and hydroxyl groups due to oxidation of the surface.

The degree of improvement in the affinity of the substrate can be evaluated by, for example, the contact angle with water. In order to put thin film particles, this contact angle is 40 degrees or less, preferably 20 degrees.
No more than a degree.

(How to Place Thin Film Particles on Substrate) In order to place the thin film particles on the surface (surface) of the substrate, a dispersion liquid of oxidized thin film particles is usually used. In the case of thin film particles having a size of about several hundreds of μm or less, it is easy to deposit a dispersion liquid containing a relatively large number of particles on a substrate, and in the case of larger thin film particles, individual particles are It is easy to recognize and place a small number such as one on the substrate, but of course the reverse combination thereof is also possible. Generally, when making fine elements or wiring, they are placed on the substrate so that they do not come into contact with other particles, so it is necessary to put a small number of them, and when making large wiring, make the same contact. Since a large number of particles are placed on the substrate at the same time.

The concentration of the dispersion liquid when the particles are placed on the substrate may be changed depending on the necessity of the number of particles at the time of use as described above. Furthermore, the concentration may be such that it provides a viscosity (fluidity) that is easy to use in the pattern formation described below. Also, other components may be added to adjust the viscosity.

As the dispersion medium of the dispersion liquid when it is placed on the substrate, a highly polar liquid having a relative dielectric constant of about 15 or more can be used as described above, but the drying speed of the dispersion medium and the low surface tension are small. If necessary, methanol or acetone is particularly desirable. This allows particles that spread well and have less wrinkles to be placed on the substrate in a short time. However, wrinkles (meandering in the thickness direction) may positively change the conductivity.

When a large number of thin film-shaped particles are placed on a substrate, the overall spread and thickness of the large number of thin film-shaped particles may be determined so that a desired shape or conductivity such as wiring can be obtained. However, if the spread is too large or the thickness is too large, it takes a long time to escape the dispersion medium and water to be released during the drying of the dispersion medium and the reduction by heating. Further, if the temperature rise is too fast during drying or reduction by heating, the dispersion medium or water that is rapidly vaporized causes separation at the interface between the substrate and the thin film particles or at the boundary between the thin film particles. Therefore, it is desirable to raise the temperature at a low speed (for example, 10 ° C./hour or less). In addition, a shape that is not too wide or a macro hole is formed even if it is wide so that the escape distance of gas is short. It is desirable that the shape and the shape not be too thick so that the amount of gas generated per unit area is small.

(Addition of Other Conductive Portions) As described above, thin film particles generally have low conductivity even when completely reduced, so that they are large (long) in electronic circuits and devices.
It is less desirable to use it for parts. Therefore, it is desirable to use, as the other conductive material, a metal having a higher conductivity than the thin-film particles in the other conductive portion such as the connection portion with the outside. In this case, if stability at high temperature is required, for example, gold may be used, and if it is not necessary to raise the temperature to high temperature, copper or aluminum may be used.

Such other conductive parts, semiconductor parts constituting other elements, insulator parts, etc. may be added in advance to the substrate before the thin film particles are placed thereon. Here, a substrate including these portions is also used. However, if such other portion is thick and has a step, the step may cause separation of particles from the substrate or cracking of particles. this is,
Especially, it becomes a problem with large particles. In this case, it is effective to make the other conductor portion or the like as thin as possible, have an embedded inlaid structure, or add another portion after the thin film particles are placed.

Further, because the anisotropy of the conductivity of the thin film particles increases the resistance at the contact portion with other conductor portions, it is desirable to increase the contact area at that portion.

In applications such as an optical element and a recording material, a connection portion with the outside is generally unnecessary.

(Pattern forming method) In order to position-selectively deposit thin film particles on a substrate or a conductor for connection to the outside, various known pattern forming methods may be used alone or in combination with this system. You can apply. In this case, it is particularly advantageous to form a pattern using oxidized thin film particles that can be treated with the dispersion liquid.

In the case of a relatively large pattern, for example, a dispersion liquid of relatively small thin film particles is used as an ink.
Patterning can be performed by using a general printing or coating method such as a screen printing method or an ink jet method, and by selectively placing it on a substrate or the like, and drying the dispersion medium (the portion to be placed and the portion to be placed). There is a pattern by the part which is not). In this case, the viscosity of the dispersion becomes important, and for example, a relatively high viscosity in the screen printing method (for example, to the extent that it does not flow even when tilted) and a low viscosity in the inkjet method are desirable. Also, after forming thin film particles on the entire surface of the substrate by spin coating or the like, patterning is performed by lithography using a resist and a mask (mainly exposed to visible light), etching of unnecessary thin film particle portions, and removal of the resist. It is also possible to form a pattern by mechanically cutting.

In the case of a small and fine pattern, for example, relatively large thin film particles are placed alone or in small numbers together with a small amount of liquid on a substrate, and the liquid is dried, or further reduced by heating or the like. After that, lithography using resist or resist and mask (exposure with ultraviolet light, electron beam, ion beam, etc. (may be scanned if mask is not used)), unnecessary inside thin film particles A pattern can be formed by etching a part and removing the resist. Alternatively, the inside of the thin film particles may be directly etched by a scanned short wavelength laser, an electron beam, an ion beam, a neutral particle beam or the like without using a resist. Furthermore, various processing by scanning probe microscope (manipulation of molecules or atomic groups, further atomic manipulation)
Can also be applied.

For pattern formation of such thin film particles,
It is also possible to combine the addition of other conductive portions or insulating portions with the pattern formation, and further, the above various steps may be repeated a plurality of times.

(Others) Electronic circuits and devices using thin film particles are soft and fragile. However, since ordinary semiconductor devices also become extremely brittle when they become particularly fine,
It is considered that there will be no problem if protected by a similar sealing method. In addition, when an electronic circuit or device using thin film particles is formed and then further processed, appropriate protection may be performed. However, especially in the case of fine devices, there is a high possibility that information will change due to external influences (radiation, heat, etc.), so more stringent protection will be applied and the same operation will be duplicated. Adopting a circuit is desirable.

Since this electronic circuit or device is formed by depositing thin film particles, voids between particles remain even after reduction. Therefore, the conductivity changes due to the adsorption of low molecules when used at low temperature, but the adsorption is eliminated when used at high temperature, so that stable operation is possible. As a method of eliminating the influence of adsorption at low temperature, it is conceivable to fill the void with another insulator, or to use a sealed container with an airtight terminal.

In the various steps from the synthesis of the thin film particles to the production of electronic circuits and devices, it is desirable to use clean raw materials and chemicals and to work in a clean environment. Especially when performing fine processing, it is necessary to prevent the entry of fine dust and the like as much as possible, and it is desirable to work in a clean room.

[0072]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Preparation of Oxidized Thin Film Particles with Spread of about 20 μm) Natural Graphite (SNO-2, SNO-2)
5. Purity 99.97 wt% or more, purified product obtained by removing impurities by heating at 2900 ° C., average particle size 24 μm, particle size 4.
6 g or less and 61 μm or more are 5 wt% each, 10 g, sodium nitrate (purity 99%) 7.5 g, sulfuric acid (purity 96
%) 621 g, potassium permanganate (purity 99%) 4
The mixture was placed in a mixed solution of 5 g and left at about 20 ° C. for 5 days with gentle stirring. The obtained high-viscosity liquid was added to 5
wt% sulfuric acid aqueous solution (conductivity of 0.1 μS / for diluted water)
It was added to 1000 cm ³ of less than 1 cm (the same applies hereinafter) with stirring for about 1 hour, and stirred for another 2 hours. Hydrogen peroxide (30 wt% aqueous solution) 30 was added to the obtained liquid.
g and stirred for 2 hours.

This solution was placed in a centrifuge bottle and centrifuged (maximum turning radius 17 cm (same below), 1000 rpm, 10 minutes)
Then, the supernatant (a little mixed with the precipitate, the same applies in the following) was discarded to leave only the precipitate. Furthermore, after adding a mixed aqueous solution of 3 wt% sulfuric acid / 0.5 wt% hydrogen peroxide (about 6 to about 4 times to the precipitate, the magnification decreases as the operation proceeds) to the precipitate while still in the centrifuge bottle, The procedure of capping, shaking the bottle to redisperse the precipitate, centrifuging (3000 rpm, 20 minutes), and discarding the supernatant was performed 15 times. A total of about 13 kg was used as the mixed aqueous solution.

The liquid to be added was replaced with water, and redispersion, centrifugation (7000 rpm, 30 minutes) and discarding of the supernatant were carried out in the same manner as above.
Repeated times. Further, water was added to redisperse the mixture, and the mixture was allowed to stand for 1 day to precipitate only a small amount of particles (thick particles, etc.) that tend to precipitate. This precipitate was removed, the liquid that did not precipitate was centrifuged (7,000 rpm, 30 minutes), and the supernatant was discarded. Except for the supernatant, the lower part of the precipitate was hard to flow and the upper part was a slightly viscous liquid, and the total amount was about 650 cm ³ .

The precipitate which is hard to flow and the liquid having a slightly high viscosity are stirred to form a homogeneous liquid, and about 1/2 thereof is used in the same manner as water (about 5 to 0.4 times, As the process progresses, the magnification decreases, and redispersion and centrifugation (7000 rp)
m, 60 minutes) and discarding the supernatant was repeated 20 times in total.
Then, a small amount of water was added and stirred to obtain a highly purified aqueous dispersion of thin film particles, 1350 cm ³ . From the weight change of a part of the liquid before and after drying, the concentration of thin film particles in the liquid was 0.45 wt%. In addition, the elemental analysis of the thin film particles dried under vacuum at 40 ° C. revealed that oxygen was about 42 wt% and hydrogen was about 2 wt%.

The obtained aqueous dispersion was placed on a glass plate and dried, and X-ray diffraction measurement was performed. A peak corresponding to 0.83 nm was obtained. This corresponds to the interlayer distance of generally known graphite oxide (when water is held between the layers).

Dilute the same aqueous dispersion 100 times with water
And place it on a glass plate to dry, and then flatten the thickness of the thin-film particles.
I tried to get the average value. Dry from the liquid and put on a glass plate
Calculated the average thickness of a large number of attached particles is about 12 nm
(The particle density is 2.1 g / cm ³And if)
In addition, about 3 particles or more are overlaid on the entire surface where the liquid spreads
Was confirmed by optical microscope (OM) observation (grain
Although the child is extremely thin, it has a higher reflectance than glass,
I was able to separate). From this, the thickness of each thin film particle is an average
It was less than 4 nm. Also, in this observation, thin film particles
It is confirmed that the average size in the plane direction is about 20 μm.
It has been certified.

(Oxidized thin film with a spread of about 2 μm or less
Preparation of particles) Small natural graphite (S Co., Ltd., S
NO-2, purified product, average particle size 2μm, particle size 5μm or more
About 5 wt%) in methanol (purity 99.8%)
Particles with relatively slow sedimentation (total
About 15 wt%) was obtained. 1 g of this separated natural graphite
Sodium nitrate 0.75g, sulfuric acid 62.1g, permanga
Approximately 20
It was left for 5 days at 0 ° C. with gentle stirring. Got
A highly viscous liquid is a 5 wt% sulfuric acid aqueous solution 300 cm ³Stir to
While stirring, the mixture was stirred for 2 hours. In the obtained liquid
Add 3 g of hydrogen peroxide (30 wt% aqueous solution) for 2 hours
It was stirred.

This liquid was purified by centrifugation using a mixed aqueous solution of 3 wt% sulfuric acid / 0.5 wt% hydrogen peroxide and centrifugation using water to obtain an aqueous dispersion of thin film particles (concentration: 0.8
5 wt%) was obtained.

From the OM observation of the diluted solution, the thickness of the thin film particles was less than 4 nm on average.

(Preparation of Single Layer Oxidized Thin Film Particles) One of the above-mentioned aqueous dispersion (concentration 0.45 wt%) of thin film particles having an average spread of about 20 μm and an average thickness of less than 4 nm. Centrifuge part (7000 rpm, 30 minutes), discard the supernatant, and part of the rest that is a slightly viscous liquid part (the part containing components of relatively large spread and relatively small thickness)
Was taken out into a glass bottle and diluted with water to about 100 times. This glass bottle was placed on a hot plate at 150 ° C., and the liquid therein was heated (boiled) for about 20 minutes.

The obtained solution was diluted about 10 times with methanol, placed on a copper mesh with a carbon microgrid and dried. This was observed in advance by OM, and after confirming the region where the thin film particles on the microgrid had a large overlap and the region where the thin film particles had a small overlap, they were observed with a transmission electron microscope.

At low magnification, in both areas, unclear wrinkles (thin film particles stand up perpendicular to the plane direction,
Also, a returning structure) was observed. When I tried to observe the wrinkles existing in the region where there is little overlap at a high magnification, it is because the wrinkles disappear due to the thermal effect of the strong electron beam,
I could not observe. On the other hand, the wrinkles in the area where there are many overlaps are observable while being unclear, probably because the wrinkled particles are reinforced by other wrinkle-free particles, especially from the narrow part of the narrow wrinkles, and the thin film particles. Became less than about 1 nm. This thickness was close to that of the base layer and was considered to be a thin-film particle having a single layer structure.

(Preparation of Oxidized Thin-Film Particles with Spread of about 1 mm) Natural graphite of large particle size (manufactured by SEC Co., Ltd., purified product, diameter about 1.4 to 2.0 mm, thickness 0.1 m)
20 scales of 20 m or less)
g, sulfuric acid 27.66 g, potassium permanganate 2.00
It was placed in a mixed solution consisting of g and left without stirring.

After 40 days, the produced reaction product was gently transferred together with the solution into 500 cm ³ of a mixed aqueous solution of 3 wt% sulfuric acid / 1 wt% hydrogen peroxide using a spoon. The products were all thinly divided into many thin transparent particles.
About half of the produced thin film particles were about 1 mm × 1 mm, and the rest were smaller particles.

From this liquid, 5 thin film-like particles of about 1 mm × 1 mm were taken out together with a small amount of liquid with a scoop, and about 30
The process of allowing the solution to stand for more than a minute and then pouring the solution and adding a new mixed aqueous solution was repeated 10 times to remove manganese ions and the like. Next, the liquid was replaced with water and replaced 10 times in the same manner to remove sulfuric acid and the like. During these purifications, the thin film-like particles were further divided, and the number was increased by about 5 times.

One of the obtained thin film-like particles was taken out with a spoon and was transferred onto a glass plate together with a small amount of liquid to dry the liquid. When observed by OM, coloring due to light interference was observed on the particles. The color changed in each part of the particle, but the color change (from purple to red) was only one cycle, and coloring was not seen because the outer periphery of the particle was particularly thin (so-called black film Therefore, the thickness of the particles was considered to be within one time the wavelength of light (about 700 nm in red).
Since this and the refractive index of the particles are expected to be 1.5 or more, the thickness of the particles was estimated to be about 500 nm or less at the thickest portion.

(Preparation of Oxidized Thin Film Particles with Spread of about 3 mm) Highly Oriented Pyrolytic Graphite (Advanced Ceramics Co
Made by rporation, STM-1, purity 99.99 wt% or more, manufactured by heating at about 3000 ° C., size in the plane direction 12 mm × 12 mm, thickness 2 mm, thickness 10
1 cleaved to 0 μm was used) was placed in a mixed solution of 0.34 g of sodium nitrate, 27.66 g of sulfuric acid, and 2.00 g of potassium permanganate, and the mixture was stirred for about 10 minutes.
Left at -20 ° C. The reaction proceeded during standing, and the graphite was split into multiple pieces in both the thickness direction and the plane direction and further swelled.

After 40 days, the produced reaction product was gently transferred together with the liquid into 500 cm ³ of a mixed aqueous solution of 3 wt% sulfuric acid / 1 wt% hydrogen peroxide using a spoon. Of the many thinly split products, only two of them remained black without splitting in the central part, but the others became transparent thin film particles. Most of them have a size of 5 mm × 5 mm or less, and an average of about 3 mm × 3 mm, and their contours are almost indefinite, and partly includes a straight line portion derived from the contour of the original graphite. I was out.

About 30 to the liquid containing the thin film particles.
The process of allowing the solution to stand for more than a minute and then pouring the solution and adding a new mixed aqueous solution was repeated 10 times to remove manganese ions and the like. Next, the liquid was replaced with water and replaced 10 times in the same manner to remove sulfuric acid and the like. During these purifications, the thin film-like particles were further divided, and the number thereof was increased by about 10 times.

One piece of the obtained thin film-like particles was taken out with a spoon and was transferred onto a glass plate with a small amount of liquid, and the liquid was dried and observed by OM. The thickness of the particles was estimated to be about 500 nm or less at the thickest part.

(Preparation of Oxidized Laminated Assembly) Methanol (25 ° C.) was added to an aqueous dispersion (concentration 0.45 wt%) of the thin film particles having an average spread of about 20 μm and an average thickness of less than 4 nm. Relative dielectric constant of 32.7) is added to 0.1
It was a dispersion liquid of wt%. Methanol was further added to this dispersion to give a 0.01 wt% methanol dispersion containing a slight amount of water. This liquid was placed in a glass container having a flat bottom at a depth of about 2 cm, covered with a lid, and allowed to stand at about 20 ° C. The thin film-like particles were precipitated during standing. Approximately 90 days later, when the liquid is gently shaken, it rises up and spreads 500μ.
Large particles with a size of m or more that can be visually confirmed were obtained.

One piece of this large particle was taken out with a small spoon with a small amount of liquid, transferred onto a glass plate, and the liquid was dried.
By OM observation, it was confirmed that the large particles were a laminated aggregate composed of a plurality of small thin film particles laminated and aggregated with each other.

Further observation was performed after heating at 500 ° C. (details of heating will be described later). Since the reflectance was increased by the reduction, the outlines of the individual thin film-like particles constituting the layered assembly became clear. Further, it was found that the number of overlapping thin film particles inside the laminated assembly varied depending on the place, but was about 10 or less on average. From this, it was considered that the thickness of the laminated assembly was several tens of nm. In addition, there was a large bend in the interior of the laminated assembly when it was placed on the glass plate. It was considered that in this large bent portion, the individual thin-film particles constituting the layered assembly were also bent, and each basic layer, which was also a large planar molecule, was also bent.

(Reduction by Heating and Change of Particles)
An aqueous dispersion of oxidized thin film-like particles having an average spread of about 20 μm and an average thickness of less than 4 nm has a spread of 1 cm × 1.
cm, about 30 μm in thickness after drying, placed on a borosilicate glass substrate, dust-protected and left at about 20 ° C., relative humidity about 40% to dry, and then temperature While increasing the temperature, vacuum heating (further peeling from the glass plate and heating in argon at a high temperature of 1200 ° C.) was performed, and the change in interlayer distance was examined by X-ray diffraction measurement (measurement was performed in air at about 2
0 ° C).

From the peak of oxide graphite (corresponding to the layer structure containing oxygen, the interlayer distance is 0.83 nm at 20 ° C.) as the heating temperature increases, the peak giving the interlayer distance is
Coexistence of peaks of graphite oxide and peaks similar to graphite (corresponding to the coexistence of a layer structure part containing oxygen and a layer structure part not containing much oxygen, 0.55
nm and 0.38 nm), corresponding to a graphite-like peak (corresponding to a layered structure containing little or no oxygen, the broadening of the peak is larger than that of graphite, the same at 300 ° C.).
7 nm, the same was 0.34 nm at 1200 ° C.).

Color tone and electric resistance (simple measurement using an ordinary tester with an electrode interval of about 1 mm, thickness of 0.5 by the same method)
mm low orientation graphite sheet is 1.5Ω), brown at 20 ° C. and 32 MΩ or more (outside the measuring range), dark brown at 20 ° C. and 20 MΩ, dark silver at 150 ° C. and 10 kΩ, 20
5Ω with silver color at 0 ℃ and 300Ω and bright silver color at 1200 ℃
It was Ω. In thermogravimetric analysis, especially,
The weight loss at around 210 ° C was remarkable.

One piece of the above-mentioned oxidation type thin film particles having a size of about 3 mm × 3 mm and a thickness of less than 500 nm was placed on a borosilicate glass substrate with a spoon and dried at room temperature. About 20 to 300 ℃ in air
The temperature was raised in time, from 300 ° C. to 500 ° C. in 1 hour, left at 500 ° C. for 1 hour, and then returned to about 20 ° C. The particles became silvery reduced.

[0100] The above-mentioned oxidation type laminated assembly on a glass plate was heated in air from about 20 ° C to 300 ° C in about 5 hours, and then heated from 300 ° C to 500 ° C in 1 hour. It was warmed, left at 500 ° C. for 1 hour and then returned to about 20 ° C.
The layered assembly became a translucent silvery reduced form.

(Exchange of Dispersion Medium) The above-mentioned aqueous dispersion of oxidized thin-film particles having an average spread of about 20 μm and an average thickness of less than 4 nm was placed in a centrifuge bottle and placed in acetone (specific dielectric at 25 ° C.). Rate 20.7, purity 99.5%, about 2 to 4 times that of the aqueous dispersion, the magnification increases as the operation proceeds), and redispersion and centrifugation (7000 rpm, 30 minutes) and discarding of the supernatant are added. Repeated 3 times. The obtained precipitate had a concentration of about 1.7 wt% and was a solid without fluidity.

Further, with this lump put in a centrifuge bottle,
2-Butanone (relative dielectric constant at 20 ° C., 18.5, purity 99%, about 4 times that of acetone dispersion) was added, and redispersion, centrifugation (7000 rpm, 30 minutes), and discarding of the supernatant were repeated 3 times in total. . The obtained precipitate has a concentration of about 2.0 wt.
%, It was a non-flowable mass.

As described above, the oxide type thin film particles were able to form a dispersion system with a liquid other than water. However, as the dielectric constant decreased, the repulsion between the particles became smaller, and it became easier to generate a higher-concentration precipitate. Further, because of its high shape anisotropy, the surrounding dispersion medium was retained even at a low concentration of several%, and the fluidity of the dispersion liquid was significantly reduced.

One piece of the above-mentioned oxidation type thin film particles having a size of about 3 mm × 3 mm and a thickness of less than 500 nm was put into methanol using a spoon and the dispersion medium was exchanged.

(Improvement of Affinity of Substrates) Affinities of various substrates were improved (hydrophilization treatment), and thereafter, oxidation type thin film particles were adhered and reduced by heating. At that time, the degree of hydrophilicity was evaluated by the contact angle with water. The contact angle is measured by dropping water on the substrate and measuring the volume of the water (for example, 3 mm ³ ) and the diameter of the contact surface of the droplet measured on the substrate (when the contact angle is less than 90 degrees) or Use the diameter (if it is 90 degrees or more),
It was calculated by assuming that the shape of the droplet is a part of a sphere.

Diamond substrate (Sumitomo Electric Industries, Ltd.)
Made, polycrystal, grown on a silicon substrate and polished on the surface, diamond layer thickness 25 μm) washed with methanol (immersed in methanol and irradiated with ultrasonic waves for 3 minutes) and then washed with water (immersed in water Ultrasonic irradiation was performed for 3 minutes, followed by drying (water was blown off with compressed air), further heating in air at 500 ° C. for 1 hour, cooling, immersion in water, and drying (same). The contact angle is 97 degrees before treatment and 52 after washing and drying.
After heating and drying, the temperature gradually changed to 8 degrees.

A silicon carbide substrate (manufactured by Hitachi Chemical Co., Ltd., polycrystalline, thickness 5 mm) was treated in the same manner as the diamond substrate. The changes in contact angle were 87 degrees, 72 degrees, and 17 degrees, respectively.

A silicon substrate (silicon wafer, single crystal, thickness 0.4 mm) was treated in the same manner as the diamond substrate. The changes in contact angle were 51 degrees, 50 degrees, and 29 degrees, respectively. Further, it was immersed in a 10 wt% sodium hydroxide aqueous solution for 1 minute and then dried (same). The contact angle was 18 degrees.

Sapphire substrate (SA1 manufactured by Kyocera Corp.)
00, single crystal, one-side polished product, thickness 0.43 mm) were treated in the same manner as the diamond substrate. The changes in contact angle were 33 degrees, 28 degrees, and 5 degrees.

A quartz glass substrate (amorphous, polished product, thickness 2 mm) was treated in the same manner as the diamond substrate. The changes in contact angle were 46, 43, and 6 degrees, respectively.

Alkali-free glass substrate (Nippon Electric Glass)
OA-10 (manufactured by KK), silica and alumina as main components, amorphous, polished product, and thickness 0.7 mm) were treated in the same manner as the diamond substrate. The change in contact angle is the same at 34 degrees, 32 degrees,
It was 14 degrees.

Borosilicate glass substrate (slide glass,
The contact angle of the amorphous material, the polishing-cleaned product, and the thickness of 1.2 mm) was 4 degrees without any treatment.

For another diamond substrate,
After sputtering (Ar ions, applied voltage 10 kV, current density 200 to 300 μA / cm ² , 6 hours), 50
It was heated at 0 ° C. for 1 hour, cooled, immersed in water, and then dried (same). The contact angle changed to 47 degrees after sputtering and 6 degrees after heating and drying.

(Observation by Atomic Force Microscope) The above-mentioned oxidation type thin film particles having an average spread of about 20 μm and an average thickness of less than 4 nm were coated with a 0.01 wt% methanol dispersion liquid on a silicon substrate (flatness). In order to avoid a decrease in the temperature as much as possible, the sample was placed on the surface (not hydrophilized here), dried and observed with an atomic force microscope, further reduced by heating at 300 ° C. for 10 minutes, returned to room temperature, and observed again.

For many particles, there were many extremely gentle wrinkles inside the particles. At some places, a step that was thought to be a structure in which thin film particles were folded was recognized. The bent portion of the thin film-like particles was sharply bent without thickening. In this part, it is considered that each basic layer, which is also a large molecule, is sharply bent. Further, in other places, a step having a certain width, which is considered to be a structure of two-stage bending in which the material is once bent and then bent to the opposite side, was recognized.

Furthermore, the change in thickness before and after heating was examined for a particularly thin portion. The 2.1-nm-thick portion in the unheated stage was changed to 1.1-nm-thick after heat reduction. This ratio is determined by the change in the lattice spacing (0.
The ratio is close to 83 nm and 0.37 nm).

(Adhesion of Thin Film Particles to Substrate) A dispersion liquid containing a large number of oxidized thin film particles (on average) on the above-mentioned hydrophilicized various substrates (each having a minimum contact angle). Spreading less than about 2 μm (concentration 0.85 wt
%) And about 20 μm (concentration 0.45 wt%), both of which are applied so that the total spread after drying is about 0.5 cm ² and the average thickness is about 2 μm), and the spread is about 2 mm ×
Oxidized thin film-like particles (1 mm thick and less than 500 nm thick)
Transferred with a scoop with a small amount of liquid), spread about 50
A total of 4 kinds of 0 μm oxidative laminated aggregates (1 sheet, the same) were placed, left standing at about 20 ° C. for 15 hours to dry, and then gradually heated up to about 50 ° C. per hour to reach the maximum. The mixture was heated and reduced at a temperature of 500 ° C. for 1 hour. Both could be placed on the substrate cleanly.

(Pattern formation by ion beam irradiation)
By irradiating a focused ion beam to remove a part of the inside of the thin film particle, the inside of the thin film particle was position-selectively processed (patterned).

The spread is about 20 on a borosilicate glass substrate.
Approximately 5 drops of 0.01 μm-thick oxidized thin-film particles as a methanol dispersion having a concentration of 0.01 μm were placed and dried.
It was reduced by heating at ℃. In order to prevent the sample from being electrified during processing, a conductive paste was applied to three sides of a processing target area of about 3 mm × 3 mm. This sample was observed with an optical microscope in advance, and a large number of thin-film particles with less contact with other particles and less macroscopic wrinkles were selected. Focused ion beam device (FB-made by Hitachi, Ltd., FB-
2000A, gallium ion source, maximum scanning range of 60 × 60 μm, minimum resolution of 10 nm in one irradiation)
Was used for fine processing. As for the shape of processing, assuming a conducting wire or a quantum structure, a mesh-shaped lattice (irradiates multiple squares with ions and leaves the boundaries of multiple squares), multiple linear shapes (elongated rectangle, minimum width is About 100 nm) and squares (irradiated with ions left around them, about 3 kinds each in size).

At an accelerating voltage of 30 kV, the current amount and the irradiation time were changed to irradiate several particles individually, and an image of secondary electrons observed during irradiation in the focused ion beam apparatus and an external optical microscope. The degree of processing was examined with the image observed in. Appropriate processing was possible with a charge amount of about 5 to 60 pC / μm ² (an ion amount of about 5 to 60 × 10 ^-17 mol / μm ² assuming monovalent ions). Further, if the irradiation amount was small with respect to the thickness of the particles, processing was insufficient, and if the irradiation amount was large, peeling occurred.

Further, the obtained processed product is observed by an atomic force microscope, and the thickness of the thin film particles is about 10 nm, and the desired shape can be processed in the height direction (particle thickness direction). It was confirmed that a fine wire having a line width of about 100 nm could be processed. In this case, the inside of each basic layer, which is also a large molecule, is processed.

As described above, it was possible to specifically pattern the inside of a single thin film particle placed on the substrate. Such a shape can be made to correspond to a fine wiring or an element by passing electricity, and to a recording material (recording medium) by treating the presence or absence of thin film particles in a processed portion as information, for example.

(Pattern formation by screen printing) A large number of thin film particles were position-selectively placed on a substrate to form a pattern.

By printing using a screen mask, a gold paste (Hereus Co., Ltd., C4350, the ratio of gold was 90 wt%, was applied on a non-alkali glass substrate (OA-10).
The paste was fixed by heating at 600 ° C., and the substrate was made hydrophilic at the same time by this heating to form wiring for external connection (two lines with a width of 1 mm and a thickness of about 20 μm with a gap of 1 mm in width).

Further, by printing using different screen masks, an aqueous dispersion of the above-mentioned oxidized thin film particles having an average spread of about 20 μm and an average thickness of less than 4 nm (concentration: 1.6 wt%, centrifugal (Concentrated by separation) is used as an ink, and 3 mm × 3
The pattern was formed into a square of mm and a thickness after drying of about 700 nm.

(Measurement of Electrical Conductivity) While the structure formed by screen printing was heated and reduced, a change in electrical conductivity (more specifically, specific electrical conductivity) was measured (measured by sequentially heating the same sample. Is in air at room temperature). Here, in the calculation of conductivity, it was assumed that the space between the gold wirings and the dimension of the patterned thin film particles in the plane direction did not change due to heating. The thickness was measured by an atomic force microscope only after heating at 200 ° C., and at other temperatures, the thickness was calculated from the change in interlayer distance obtained by X-ray diffraction and used. The conductivity is 0.0027 S / m or less when unheated (the resistance value is outside the measurement range), 0.0029 S / m or less after heating at 100 ° C. for 30 minutes (the same), 120 S / m after heating at 200 ° C. for 210 minutes, Three
220 S / m by vacuum heating at 00 ° C for 90 minutes, 400 ° C, 9
It was 780 S / m in 0 minute vacuum heating and 500 ° C. and 1600 S / m in 90 minute vacuum heating.

By another printing using a screen mask, a gold paste (Hereus Co., Ltd., RP20003, the ratio of gold was 20 wt.%) Was formed on a sapphire substrate (SA100).
%, The paste is fixed by heating at 850 ° C., and the substrate is made hydrophilic at the same time by this heating) The wiring for the first external connection (width 1 mm)
2 parallel strip-shaped lines having a width of 1 mm and a thickness of about 0.3 μm) were prepared. Gold paste (Heraus Co., C575
The second wiring (thickness: about 20 μm) was formed by 5 A, the ratio of gold was 86 wt%, and the paste was fixed by heating at 850 ° C. Furthermore, a small amount of the above-mentioned oxidation type thin film particle having a size of about 3 mm × 3 mm and a thickness of less than 500 nm is placed at a position where two parts of the particle overlap with each of the two first wirings. Place it with a spoon and dry it. The change in conductivity was measured while the structure was heated and reduced. The electrical conductivity is 0.0020 S / m or less when unheated (the resistance value is outside the measurement range), and 0.002 after heating at 100 ° C. for 30 minutes.
2.2 at 1 S / m or less (same) at 200 ° C for 210 minutes
S / m, 300 ℃, 90 minutes vacuum heating 5.2 S / m, 4
Vacuum heating at 00 ℃ for 90 minutes 37S / m, 500 ℃, 90
It was 96 S / m by minute vacuum heating. In addition, it was confirmed that the contact portion with the gold wiring was ohmic contact.

[0128]

EFFECT OF THE INVENTION A structure in which thin film particles having a carbon skeleton (oxidation type and reduction type carbon nanofilm) of the present invention are placed on a substrate has an electronic physical property unique to a carbon-based substance having a periodic structure. It is a new system that can easily use stability, etc., and has fine circuits (elements and wiring), high temperature circuits (the same),
It can be applied to photoelectric conversion elements (solar cells, light emitting elements, etc.), heating elements, optical elements, stable recording materials, and the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a form and a manufacturing method when mounted on a substrate with electrodes (an example of a fine circuit, a case of using beam processing, etc.)

2A and 2B are schematic diagrams of a form and a manufacturing method when mounted on a substrate with electrodes (an example of a relatively large circuit, a case where printing or the like is used).

FIG. 3 is a schematic diagram of an example in which electrical properties are changed depending on the shape (in the case of a field effect transistor, the thickness direction is also processed).

FIG. 4 is a schematic diagram of an example in which electrical properties are changed depending on the shape (in the case of a field effect transistor, the thickness direction remains constant (especially when thin)).

FIG. 5 is a schematic diagram of an example (in the case of a resistor) of changing electrical properties depending on the shape.

FIG. 6 is a schematic diagram of an example of connection with another good conductor (in the case of connection with external wiring).

FIG. 7: Atomic force microscope image of bending of thin film particles (light-colored part on the right side is a silicon wafer, there is a bending part in the left-right direction near the center)

FIG. 8 is an optical microscope image of a processing example inside a particle (a white portion is an area removed by a focused ion beam).

FIG. 9 is an atomic force microscope image of a processed example of the inside of a particle (a part processed into a square).

FIG. 10 is an atomic force microscope image (a part of two kinds of lines (band-shaped structure)) of a processing example inside a particle.

[Explanation of symbols]

1 Substrate 2 in the Present Invention Insulator Part 3 Good Conductor Part 4 1 Thin Film Particle (Oxidation Type) 5 1 Thin Film Particle (Reduction Type) 6 1 Thin Film Particle with Internal Pattern Formed (Reduction Type) ) 7 A large number of patterned thin film particles (oxidized type) 8 A large number of patterned thin film particles (reduced type) 10 A patterned thin film particle 11 Semiconductor part (particularly narrow part) 12 Good conductor part (wiring) ) 13 good conductor part corresponding to source electrode (wide part that secures current amount in thickness direction) 14 good conductor part corresponding to drain electrode (wide part that secures current amount in thickness direction) 15 good conductor part (source electrode on the semiconductor side) 16 Good conductor part (semiconductor side is equivalent to drain electrode) 17 High conductor good conductor part 18 Connection part with external wiring (wide part that secures current amount in thickness direction) 20 Thin Insulator portion 30 gate electrode substantial good conductor portion (wiring, especially not the entire surface in the case of such an integrated circuit) 40 insulator portion 50 outside of the conductor portion (wiring)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/288 H01L 21/288 M 21/3205 29/06 601N 29/06 601 21/88 B 51/00 29/28 F-term (reference) 4G046 EA06 EB00 EB06 EB13 EC02 EC03 EC05 EC06 4M104 BB36 DD21 DD51 DD65 DD78 DD79 DD81 5F033 HH00 HH35 PP26 QQ00 QQ14 QQ53 QQ59 QQ64 QQ65 QQ73 QQ91 WW01 WW10 5W02 WW02 WW02 5W03 WW02 5W05 WW02 WW02 WW02 WW02 WW02 WW02 WW02 WW05 WW02

Claims (20)

[Claims] 1. A lyophilic liquid (a) which is obtained by oxidizing graphite and has a thickness of 0.4 nm to 10 μm, a size in the plane direction of at least twice the thickness, and a relative dielectric constant of 15 or more. Having a skeleton made of carbon, a single or a plurality of oxidation type thin film particles, or an oxidation type laminated assembly in which a plurality of the oxidation type thin film particles are laminated and bonded to each other, or
(B) A reducing type alone or a reducing type obtained by partially or completely reducing the oxygen-containing thin film-like particles or a laminated aggregate of the oxide-type thin film-like particles so that the oxygen content becomes 0 to 35 wt%. A structure comprising a plurality of thin-film particles or a reduction-type laminated assembly thereof and (c) a substrate in contact with each other. 2. A substrate comprising (c1) an electrical insulator, a semiconductor, or a good conductor, or a (c2) electrical insulator, semiconductor, or a good conductor, which are position-selective. The structure according to claim 1, wherein a substrate having an internal structure arranged in is used. 3. A pattern is formed by arranging a plurality of oxidized or reduced thin film particles or a plurality of laminated aggregates on a substrate in a position-selective manner. The structure according to claim 1 and claim 2. 4. The oxidation-reducing or reducing-type single or plural thin-film particles or laminated aggregates are position-selectively patterned inside. Structure. 5. The degree of reduction of the thin film particles or the laminated aggregate and the shape, width and thickness of various structures such as a single structure or a plurality of strip-shaped structures obtained by patterning the thin film particles or the laminated aggregate ( The number of layers), the orientation of the carbon skeleton, the stacking state of a plurality of layers, the type of atoms end-bonded to the carbon skeleton, etc. are changed to change the electronic state, thereby changing the electrical properties. The structure according to any one of claims 1 to 4. 6. The structure according to claim 1, wherein the electrical property is changed by using a field effect doping method. 7. The thickness obtained by oxidizing graphite is 0.4.
nm to 10 μm, the size in the planar direction is twice or more the thickness, the relative dielectric constant is 15 or more, and the liquid is lyophilic and has a carbon skeleton. Particles, or a thin film-like particle or a thin film-like particle stacking assembly by placing an oxidation-type stacking assembly in which a plurality of thin film-like particles are stacked and bonded to each other on a surface of a substrate and then partially or completely reduced. Oxygen content of body is 0 ~ 35wt
%, The method for producing a structure according to claim 1 or 2. 8. A pattern is formed by position-selectively placing on a substrate using a dispersion liquid in which oxidized thin film particles are dispersed in a liquid having a relative dielectric constant of 15 or more. ~ The method for producing a structure according to claim 3. 9. A pattern is formed by position-selectively removing or thinning a part of the inside of a single or plural thin-film particles or a laminated aggregate of the oxidation type or the reduction type placed on the surface of a substrate. The method for producing a structure according to claim 1, wherein: 10. The method of manufacturing a structure according to claim 1, wherein a substrate having a surface affinity increased so that a contact angle with water is 40 degrees or less is used. 11. The affinity of the surface of the substrate is increased by heating or heating and immersion in water.
A method for manufacturing the structure according to. 12. The method for producing a structure according to claim 1, wherein the structure is reduced by heating, a reducing agent or an electrode reaction. 13. A heating rate of 10 ° C./hour or less,
The method for producing a structure according to claim 12, wherein the structure is heated and reduced at a maximum temperature of 150 ° C. or higher. 14. An electronic device, such as a transistor, a resistor, or a capacitor, which uses the structure according to any one of claims 1 to 6. 15. A conductor portion for wiring, which uses the structure according to any one of claims 1 to 6. 16. An integrated circuit using the structure according to claim 1. Description: 17. A photoelectric conversion element, such as a solar cell or a light emitting element, which uses the structure according to any one of claims 1 to 6. 18. A heating element using the structure according to claim 1. 19. An optical element using the structure according to any one of claims 1 to 6. 20. A stable recording material using the structure according to any one of claims 1 to 6.