JP5500850B2 - Method for producing carbon nanotube - Google Patents
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Description
本発明は、所定の長さおよび重量（密度）を有するカーボンナノチューブ（ＣＮＴ）を安定的に製造することができるカーボンナノチューブの製造方法に関するものである。 The present invention relates to a carbon nanotube production method capable of stably producing carbon nanotubes (CNT) having a predetermined length and weight (density).
カーボンナノチューブは、炭素原子が六角網目状に配列したグラフェンシートを筒状に丸めた立体構造を持つ。種類は１枚のグラフェンシートから成る単層カーボンナノチューブや、複数枚のグラフェンシートから成る多層カーボンナノチューブがあり、いずれも通常、カーボンナノチューブの先端は半球状のグラファイト層で閉じられた構造となっている。 The carbon nanotube has a three-dimensional structure in which a graphene sheet in which carbon atoms are arranged in a hexagonal network is rounded into a cylindrical shape. There are single-walled carbon nanotubes composed of a single graphene sheet and multi-walled carbon nanotubes composed of multiple graphene sheets, both of which usually have a structure in which the tip of the carbon nanotube is closed with a hemispherical graphite layer. Yes.
カーボンナノチューブの特徴は、ｎｍオーダーの直径と、μｍオーダーの長さを有しており、アスペクト比が極めて大きい点である。またカーボンナノチューブは機械的にも強靭であり、化学的・熱的安定性に優れ、円筒部の螺旋構造に応じて金属にも半導体にもなるという特長がある。それゆえ、ＬＳＩに代表される半導体装置や加速度センサ等の各種センサ、電子デバイスや放熱デバイス等、幅広い分野への適用が期待されている。そのためには、必要な所定の長さおよび重量（密度）を有するカーボンナノチューブを安定的に作成することが重要となる。 The feature of the carbon nanotube is that it has a diameter on the order of nm and a length on the order of μm, and has an extremely large aspect ratio. Carbon nanotubes are mechanically tough, have excellent chemical and thermal stability, and can be used as either metal or semiconductor depending on the helical structure of the cylindrical portion. Therefore, it is expected to be applied to a wide range of fields such as semiconductor devices typified by LSIs, various sensors such as acceleration sensors, electronic devices and heat dissipation devices. For that purpose, it is important to stably produce carbon nanotubes having a required predetermined length and weight (density).
所定の長さおよび重量（密度）を有するカーボンナノチューブの製造方法としては、例えば、基板に２次元規則配列した開口部を設け、基板と対向電極間にバイアス電圧を印加した状態で基体表面に炭素含有化合物ガスを供給し、前記炭素含有化合物ガスを熱分解させることで、基板表面に対してカーボンナノチューブをほぼ垂直に配向して成長させ、かつ、カーボンナノチューブの直径、層数及び数密度を制御することが可能なカーボンナノチューブの製造する方法が知られている（特許文献１）。 As a method for producing a carbon nanotube having a predetermined length and weight (density), for example, a two-dimensional regular array of openings is provided in the substrate, and a bias voltage is applied between the substrate and the counter electrode, and carbon is applied to the substrate surface. By supplying the compound gas and thermally decomposing the carbon-containing compound gas, the carbon nanotubes are grown almost perpendicularly to the substrate surface, and the diameter, number of layers, and number density of the carbon nanotubes are controlled. A method for producing carbon nanotubes that can be used is known (Patent Document 1).
また、基板表面に触媒金属薄膜を形成し、該薄膜を空気雰囲気で加熱することで、基板表面に分散したナノ粒子を形成し、該粒子を核として均一かつ制御されたカーボンナノチューブを製造する方法が知られている（特許文献２）。 Also, a method of forming a catalytic metal thin film on a substrate surface, heating the thin film in an air atmosphere to form nanoparticles dispersed on the substrate surface, and producing uniform and controlled carbon nanotubes using the particles as nuclei Is known (Patent Document 2).
しかしながら、前記のようなカーボンナノチューブの製造方法においては、所定の長さおよび重量（密度）を有するカーボンナノチューブを安定的に製造することは困難であった。これは、触媒金属として基板表面に蒸着した鉄などの金属からなる触媒金属薄膜の一部が酸化されるため、触媒金属薄膜の状態を均一に保つことができず、基板の表面状態が一定しないことが主な要因と考えられる。この触媒金属薄膜の状態のわずかな違いが、カーボンナノチューブ生成のためのカーボンと触媒の反応度へのばらつきとなって影響を及ぼし、長さおよび重量（密度）の安定したカーボンナノチューブの生成が困難となっている。この解決のためには、触媒金属薄膜をカーボンナノチューブ形成のための化学気相蒸着（ＣＶＤ）直前まで一定の状態に保つように触媒金属蒸着後からＣＶＤ直前まで真空下で保管する必要があり、それに係る手間と費用が大きくなるという問題があった。 However, in the method for producing carbon nanotubes as described above, it has been difficult to stably produce carbon nanotubes having a predetermined length and weight (density). This is because a part of the catalyst metal thin film made of metal such as iron deposited on the substrate surface as the catalyst metal is oxidized, so the state of the catalyst metal thin film cannot be kept uniform and the surface state of the substrate is not constant. This is considered to be the main factor. This slight difference in the state of the catalytic metal thin film affects the reactivity of carbon and the catalyst to produce carbon nanotubes, and it is difficult to produce carbon nanotubes with stable length and weight (density). It has become. In order to solve this problem, it is necessary to store the catalyst metal thin film under vacuum from after the catalyst metal deposition to just before the CVD so as to maintain a constant state until just before chemical vapor deposition (CVD) for carbon nanotube formation, There has been a problem that the labor and cost associated with this increase.
そこで、本発明では前記のような手間や費用を掛けずに、所定の長さおよび重量（密度）を有するカーボンナノチューブを安定的に製造することができるカーボンナノチューブの製造方法を提供するものである。 Therefore, the present invention provides a method for producing carbon nanotubes, which can stably produce carbon nanotubes having a predetermined length and weight (density) without taking the labor and cost as described above. .
本発明は、
基板上にＦｅからなる触媒金属薄膜を形成する工程と、
前記触媒金属薄膜の金属を微粒化する工程と、
前記触媒金属の微粒子を核として基板上にカーボンナノチューブを形成する工程を含むカーボンナノチューブの生成方法において、
前記触媒金属薄膜の金属を微粒化する工程を、５〜１５％の酸素雰囲気中で７００℃以上〜９００℃未満での１０〜６０分間の加熱により行うことを特徴とする
カーボンナノチューブの生成方法である。
The present invention
Forming a catalyst metals thin film composed of Fe on a substrate,
Atomizing the metal of the catalyst metal thin film;
In the method for producing carbon nanotubes, comprising the step of forming carbon nanotubes on a substrate with the catalyst metal fine particles as nuclei,
In the method for producing carbon nanotubes, the step of atomizing the metal of the catalyst metal thin film is performed by heating at 700 ° C. to less than 900 ° C. for 10 to 60 minutes in a 5 to 15% oxygen atmosphere. is there.
本発明によれば、基板上に触媒金属薄膜を形成後、５〜１５％の酸素雰囲気中で７００℃以上〜９００℃未満で加熱したのち、ＣＶＤ法などの方法でカーボンナノチューブを製造することにより、基板表面に蒸着によって形成した触媒金属薄膜が大気中に曝されるなどして生じた被覆層が除去されるとともに、触媒金属を基板全面に均一に分布させ準安定的状態（例えば、Ｆｅ触媒を酸化鉄に）とすることにより、触媒金属と原料ガス中のカーボンとの反応のばらつきが抑制されるため、原料ガスの濃度やＣＶＤの温度等の条件に応じて基板全面に渡って均一な長さおよび重量のカーボンナノチューブが生成され、さらに前記方法を繰り返すことで、前記均一な長さおよび重量のカーボンナノチューブが安定的に製造される。 According to the present invention, after forming a catalytic metal thin film on a substrate, heating at 700 ° C. or more and less than 900 ° C. in a 5 to 15% oxygen atmosphere, and then producing carbon nanotubes by a method such as a CVD method In addition, a coating layer formed by exposing the catalytic metal thin film formed on the substrate surface by vapor deposition to the atmosphere is removed, and the catalytic metal is uniformly distributed over the entire surface of the substrate so as to be in a metastable state (for example, Fe catalyst). Variation of the reaction between the catalyst metal and the carbon in the source gas is suppressed, so that it is uniform over the entire surface of the substrate according to the conditions such as the concentration of the source gas and the CVD temperature. Carbon nanotubes having a length and a weight are generated, and the above-described method is repeated to stably produce the carbon nanotubes having a uniform length and a weight.
以下、本発明によるカーボンナノチューブの製造方法について、詳しく説明をする。 Hereinafter, the carbon nanotube production method according to the present invention will be described in detail.
基板上に触媒金属からなる薄膜を形成する工程において、基板は、例えばシリコン製やガラス製のものであってよい。基板の厚さは０．７ｍｍ程度ないしはそれ以下であってよい。 In the step of forming a thin film made of a catalytic metal on the substrate, the substrate may be made of, for example, silicon or glass. The thickness of the substrate may be about 0.7 mm or less.
基板上に触媒金属粒子からなる薄膜を形成するには、ＥＢ（電子ビーム蒸着法）、触媒金属の化合物を含む液を超音波振動によりまたは超音波を伴ったスプレーにより基板表面に噴霧し、形成された噴霧層を加熱する方法などが好ましい。それ以外の方法として、触媒金属の化合物を含む液をスプレーや刷毛で基板に塗布した後、プラズマ照射または加熱する方法、同触媒をクラスター銃で打ち付け、乾燥させ、必要であれば加熱する方法、金属を化学蒸着させる方法、金属を基板に電子ビーム蒸着しその後この塗膜または蒸着膜を加熱方法等が採用できる。触媒金属は、鉄、コバルト、ニッケルなどであってよく、触媒金属の化合物は例えば鉄カルボニル錯体（ペンタカルボニル鉄等）のような錯体の形態、金属アルコキシド（Ｆｅ（ＯＥｔ）３等）の形態をとっていてもよい。溶媒はアセトン、アルコール等であってよい。溶液中の金属錯体や金属アルコキシドの濃度は例えば１〜５重量％であってよい。薄膜の厚みは、厚過ぎると加熱による金属粒子化が困難になるので、好ましくは１〜１００ｎｍである。 To form a thin film made of catalytic metal particles on a substrate, EB (electron beam evaporation method), a liquid containing a catalyst metal compound is sprayed onto the substrate surface by ultrasonic vibration or spraying with ultrasonic waves. A method of heating the sprayed layer is preferable. As other methods, after applying a liquid containing a catalyst metal compound to the substrate with a spray or brush, a method of plasma irradiation or heating, a method of striking the catalyst with a cluster gun, drying, and heating if necessary, A method of chemical vapor deposition of metal, a method of heating the coating film or vapor deposition film after the metal is deposited on the substrate by electron beam can be employed. The catalytic metal may be iron, cobalt, nickel, etc., and the catalytic metal compound may be in the form of a complex such as an iron carbonyl complex (pentacarbonyliron or the like) or a metal alkoxide (Fe (OEt) 3 or the like). It may be taken. The solvent may be acetone, alcohol or the like. The concentration of the metal complex or metal alkoxide in the solution may be, for example, 1 to 5% by weight. The thickness of the thin film is preferably 1 to 100 nm because it is difficult to form metal particles by heating if it is too thick.
つぎに、前記触媒金属薄膜の金属を微粒化する工程では、５〜１５％の酸素雰囲気中で７００℃以上〜９００℃未満で１０〜６０分間加熱を行う。 Next, in the step of atomizing the metal of the catalytic metal thin film, heating is performed at 700 ° C. or more and less than 900 ° C. for 10 to 60 minutes in a 5 to 15% oxygen atmosphere.
この工程において、酸素雰囲気中の酸素濃度が５％未満であると、被覆化合物層を完全に除去することができず、触媒金属と原料ガス中のカーボンとの反応のばらつきが生じ、均一な長さおよび重量のカーボンナノチューブを安定的に製造することができず、１５％を超えると、被覆化合物層は完全に除去することができるものの、新たな金属酸化物層の形成を引き起こし、触媒作用の阻害原因となり、均一な長さおよび重量のカーボンナノチューブを安定的に製造することができないので好ましくない。 In this step, if the oxygen concentration in the oxygen atmosphere is less than 5%, the coating compound layer cannot be completely removed, resulting in variations in the reaction between the catalyst metal and the carbon in the source gas, resulting in a uniform length. In this case, when the carbon nanotubes cannot be stably produced, the coating compound layer can be completely removed, but the formation of a new metal oxide layer is caused. This is a cause of inhibition, and it is not preferable because a carbon nanotube having a uniform length and weight cannot be stably produced.
加熱温度は７００℃以上〜９００℃未満が好ましい。加熱温度は７００℃未満であるとカーボンナノチューブの長さおよび重量のバラツキが大きく、９００℃以上では触媒金属であるFeと下層のSiが化合物を形成してしまい、Feの触媒機能が損なわれるので、いずれも好ましくない。 The heating temperature is preferably 700 ° C. or higher and lower than 900 ° C. When the heating temperature is less than 700 ° C., the length and weight of the carbon nanotubes vary greatly. When the heating temperature is 900 ° C. or more, Fe, which is the catalytic metal, forms a compound, and the catalytic function of Fe is impaired. Neither is preferred.
加熱時間は加熱温度とも関係するが、１０分以上が好ましい。加熱温度が１０分未満であるとカーボンナノチューブの長さおよび重量のバラツキが大きく好ましくない。 Although heating time is related also with heating temperature, 10 minutes or more are preferable. When the heating temperature is less than 10 minutes, variations in length and weight of the carbon nanotubes are large, which is not preferable.
前記酸素雰囲気中とは、酸素濃度が大気中より低い場合又は高い場合は、例えば容器中（後段で熱ＣＶＤ装置［反応炉］内で行っても良い）に触媒金属薄膜が形成された基板を設置し、容器中に酸素濃度を変化させたボンベにガスを導入する方法や、容器内を窒素などで置換し、次いで所定濃度の酸素を添加する方法などが用いられる。酸素以外の物質は特に限定しないが、カーボンナノチューブの生成に影響の少ない不活性ガス（窒素、ヘリウム、アルゴン、キセノンなど）を用いるが好ましい。 In the oxygen atmosphere, when the oxygen concentration is lower or higher than that in the atmosphere, for example, a substrate on which a catalytic metal thin film is formed in a container (may be performed in a thermal CVD apparatus [reactor] at a later stage). For example, a method of introducing gas into a cylinder whose oxygen concentration is changed in the container, a method of replacing the inside of the container with nitrogen or the like, and then adding oxygen of a predetermined concentration are used. The substance other than oxygen is not particularly limited, but it is preferable to use an inert gas (nitrogen, helium, argon, xenon, etc.) that has little influence on the formation of carbon nanotubes.
前記加熱処理により、基板上の触媒金属薄膜は一様に酸化され、微粒化され、直径１〜５０ｎｍ程度の金属触媒粒子が形成される。 By the heat treatment, the catalyst metal thin film on the substrate is uniformly oxidized and atomized to form metal catalyst particles having a diameter of about 1 to 50 nm.
次に、前記触媒金属の微粒子を核として基板上にカーボンナノチューブを形成する工程では、ＣＶＤ法を行う。原料ガスは通常はアセチレン（Ｃ２Ｈ２）ガスであるが、炭素を含有するものであれば特に限定されず、たとえば、メタン、エタン、プロパン、ヘキサンなどのアルカン類、エチレン、プロピレンの不飽和有機化合物、ベンゼン、トルエンなどの芳香族化合物なども用いることができる。
Next, in the step of forming carbon nanotubes on the substrate using the fine particles of the catalyst metal as nuclei, a CVD method is performed. The source gas is usually acetylene (C 2 H 2 ) gas, but is not particularly limited as long as it contains carbon. For example, alkanes such as methane, ethane, propane and hexane, ethylene and propylene unsaturated Organic compounds, aromatic compounds such as benzene and toluene can also be used.
アセチレンの場合、多層構造で太さ１２〜３８ｎｍのカーボンナノチューブが基板表面にブラシ毛状に形成される。原料ガスはヘリウムやアルゴン、キセノン、窒素のような不活性ガスで希釈された状態で原料ガス供給管を経て反応ゾーンに供給してもよい。ガス供給は連続的に行っても断続的に行ってもよい。ＣＶＤ法の操作条件は、好ましくは、大気圧下で、温度７００〜９００℃、加熱時間１０〜１５分が好ましい。 In the case of acetylene, carbon nanotubes having a multilayer structure and a thickness of 12 to 38 nm are formed in the shape of brush hairs on the substrate surface. The source gas may be supplied to the reaction zone through a source gas supply pipe in a state diluted with an inert gas such as helium, argon, xenon, or nitrogen. The gas supply may be performed continuously or intermittently. The operating conditions of the CVD method are preferably a temperature of 700 to 900 ° C. and a heating time of 10 to 15 minutes under atmospheric pressure.
カーボンナノチューブの長さは好ましくは１〜１０μｍ、直径は好ましくは２０〜３０ｎｍ、カーボンナノチューブ相互間の間隔は好ましくは１００〜１５０ｎｍである。 The length of the carbon nanotube is preferably 1 to 10 μm, the diameter is preferably 20 to 30 nm, and the distance between the carbon nanotubes is preferably 100 to 150 nm.
つぎに、本発明を具体的に説明するために、本発明の実施例およびこれとの比較を示すための比較例をいくつか挙げる。 Next, in order to specifically explain the present invention, some examples of the present invention and comparative examples for showing comparison with the examples will be given.
実施例１
（１）シリコン基板（５０×５０×０．７ｍｍ）の表面にカーボンナノチューブ生成用の触媒としてＥＢ（電子ビーム蒸着法）によりＦｅを蒸着させ、厚さ５ｎｍのＦｅ蒸着層を形成した。
Example 1
(1) Fe was vapor-deposited on the surface of a silicon substrate (50 × 50 × 0.7 mm) by EB (electron beam vapor deposition) as a catalyst for producing carbon nanotubes to form a 5 nm thick Fe vapor deposition layer.
次いで、Ｆｅ蒸着層を有する基板（７枚）をそれぞれ以下の条件で加熱処理した。 Subsequently, the board | substrate (7 sheets) which has Fe vapor deposition layer was heat-processed on the following conditions, respectively.
・処理条件１：未処理すなわちＥＢによるＦｅ蒸着後の状態のまま加熱せず
・処理条件２：酸素濃度５％の雰囲気中で５００℃で１０分加熱
・処理条件３：酸素濃度５％の雰囲気中で６００℃で１０分加熱
・処理条件４：酸素濃度５％の雰囲気中で７００℃で１０分加熱
・処理条件５：酸素濃度５％の雰囲気中で８００℃で１０分加熱
・処理条件６：酸素濃度５％の雰囲気中で８８０℃で１０分加熱
・処理条件７：酸素濃度５％の雰囲気中で９００℃で１０分加熱
・ Processing condition 1: Untreated, that is, not heated in the state after Fe deposition by EB ・ Processing condition 2: Heated at 500 ° C. for 10 minutes in an atmosphere with an oxygen concentration of 5%. ・ Processing condition 3: An atmosphere with an oxygen concentration of 5% Heating at 600 ° C. for 10 minutes / Processing condition 4: Heating at 700 ° C. for 10 minutes in an atmosphere having an oxygen concentration of 5% / Processing condition 5: Heating /
加熱処理後のＦｅ蒸着層を有する基板（７枚）をそれぞれ反応管内に設置し、ＣＶＤ法を１０回実施し，触媒金属の微粒子を核として基板上にカーボンナノチューブを形成した。ＣＶＤ装置の構成を図１に示す。ＣＶＤ条件は、温度７００℃、時間１５分、原料ガスにはアセチレンガスを用い、不活性ガスには窒素ガスを用い、アセチレンガスの濃度を１５％とした。
Substrates (7 sheets) each having an Fe vapor-deposited layer after heat treatment were placed in a reaction tube, and the CVD method was carried out 10 times to form carbon nanotubes on the substrate with catalyst metal fine particles as nuclei. The structure of the CVD apparatus is shown in FIG. The CVD conditions were
ＣＶＤ法の実施回数毎に得られたカーボンナノチューブの長さを走査型電子顕微鏡（ＳＥＭ）により測定した。カーボンナノチューブの長さ測定は、図１１に示すように、正方形の基板において各辺に沿って５ｍｍ内側に設けられた４辺で形成される正方形の四隅部で実施し、得られた値の平均値を求めた。 The length of the carbon nanotube obtained for each execution of the CVD method was measured with a scanning electron microscope (SEM). As shown in FIG. 11, the length of the carbon nanotubes was measured at the four corners of a square formed by four sides provided 5 mm inside along each side in a square substrate, and the average of the obtained values The value was determined.
カーボンナノチューブの重量はCVD前後に測定した重量の差から求めた。ばらつきは、長さ、重量共に平均値を求めた後、算出した。 The weight of the carbon nanotube was obtained from the difference in weight measured before and after the CVD. The variation was calculated after obtaining an average value for both length and weight.
これらの測定結果を図２〜４に示す。図４より、酸素濃度５％の雰囲気中で７００℃以上の加熱処理を行うと、カーボンナノチューブ長さおお重量のばらつきは１０％以下まで抑えることが可能であることがわかった。ただし９００℃では蒸着したＦｅが基板のシリコンと反応してシリサイドを形成するため、垂直配向カーボンナノチューブは生成しなかった（上記処理条件１、２、３および７は比較のためのものであり本発明には相当しない）。
These measurement results are shown in FIGS. From FIG. 4, it was found that when the heat treatment at 700 ° C. or higher is performed in an atmosphere having an oxygen concentration of 5%, the variation in length and weight of the carbon nanotubes can be suppressed to 10% or less. However, at 900 ° C., the deposited Fe reacts with the silicon of the substrate to form silicide, so that vertically aligned carbon nanotubes were not generated (the
実施例２
実施例１と同様の操作で得られた、Ｆｅ蒸着層を有する基板（５０×５０×０．７ｍｍ、Ｆｅ蒸着層の厚さ５ｎｍ、７枚）をそれぞれ以下の条件で加熱処理した。
Example 2
Substrates (50 × 50 × 0.7 mm, Fe deposited
・処理条件１：酸素濃度０．５％の雰囲気中７００℃で１０分加熱
・処理条件２：酸素濃度１％の雰囲気中７００℃で１０分加熱
・処理条件３：酸素濃度５％の雰囲気中７００℃で１０分加熱
・処理条件４：酸素濃度１０％の雰囲気中７００℃で１０分加熱
・処理条件５：酸素濃度１５％の雰囲気中７００℃で１０分加熱
・処理条件６：酸素濃度３０％の雰囲気中７００℃で１０分加熱
・処理条件７：酸素濃度４０％の雰囲気中７００℃で１０分加熱
Treatment condition 1: Heating at 700 ° C. for 10 minutes in an atmosphere with an oxygen concentration of 0.5% Treatment condition 2: Heating at 700 ° C. for 10 minutes in an atmosphere with an oxygen concentration of 1% Treatment condition 3: In an atmosphere with an oxygen concentration of 5% Heating at 700 ° C. for 10 minutes and treatment condition 4: Heating at 700 ° C. for 10 minutes in an atmosphere having an oxygen concentration of 10% Treatment condition 5: Heating at 700 ° C. in an atmosphere at an oxygen concentration of 15% and treatment condition 6:
実施例１と同様の操作および条件でＣＶＤ法を１０回実施し、触媒金属の微粒子を核として基板上にカーボンナノチューブを形成した。 The CVD method was carried out 10 times under the same operation and conditions as in Example 1, and carbon nanotubes were formed on the substrate with catalyst metal fine particles as nuclei.
ＣＶＤ法の実施回数毎に得られたカーボンナノチューブの長さ、重量およびこれらのばらつきを実施例１と同様の方法で求めた。これらの測定結果を図５〜７に示す。図７より、酸素濃度５〜１５％の雰囲気中では、カーボンナノチューブの長さおよび重量のばらつきは１０％以下まで抑えることがわかる。なお、図５〜７には記載していないが、酸素濃度が３０％を超えると蒸着したＦｅが基板から剥離したため、カーボンナノチューブは生成しなかった（上記処理条件１、２、６、７は比較のためのものであり本発明には相当しない）。
The length and weight of the carbon nanotubes obtained each time the CVD method was performed and variations thereof were determined in the same manner as in Example 1. These measurement results are shown in FIGS. From FIG. 7, it can be seen that the variation in length and weight of the carbon nanotubes is suppressed to 10% or less in an atmosphere having an oxygen concentration of 5 to 15%. Although not shown in FIGS. 5 to 7, when the oxygen concentration exceeded 30%, the deposited Fe was peeled off from the substrate, so that carbon nanotubes were not generated (the
実施例３
実施例１と同様の操作で得られた、Ｆｅ蒸着層を有する基板（５０×５０×０．７ｍｍ、Ｆｅ蒸着層の厚さ５ｎｍ、４枚）をそれぞれ以下の条件で加熱処理した。
Example 3
The substrate (50 × 50 × 0.7 mm, the thickness of the Fe deposited
・処理条件１：酸素濃度５％の雰囲気中７００℃で５分加熱
・処理条件２：酸素濃度５％の雰囲気中７００℃で１０分加熱
・処理条件３：酸素濃度５％の雰囲気中７００℃で３０分加熱
・処理条件４：酸素濃度５％の雰囲気中７００℃で４０分加熱
Treatment condition 1: Heating at 700 ° C. for 5 minutes in an atmosphere with an oxygen concentration of 5% Treatment condition 2: Heating at 700 ° C. for 10 minutes in an atmosphere with an oxygen concentration of 5% Treatment condition 3: 700 ° C. in an atmosphere with an oxygen concentration of 5% Heating for 30 minutes and treatment conditions 4: Heating at 700 ° C. for 40 minutes in an atmosphere with an oxygen concentration of 5%
実施例１と同様の操作および条件でＣＶＤ法を１０回実施し、触媒金属の微粒子を核として基板上にカーボンナノチューブを形成した。 The CVD method was carried out 10 times under the same operation and conditions as in Example 1, and carbon nanotubes were formed on the substrate with catalyst metal fine particles as nuclei.
ＣＶＤ法の実施回数毎に得られたカーボンナノチューブの長さ、重量およびこれらのばらつきを実施例１と同様の方法で求めた。これらの測定結果を図８〜１０に示す。図１０より、加熱処理時間１０分以上において、カーボンナノチューブ長さおよび重量のばらつきは１０％以下まで抑えることができることがわかる。また、図１０から明らかなように、加熱時間を６０分としてもばらつきの程度は小さいままであるが、コストの点から長時間加熱をする必要はない（上記処理条件１は比較のためのものであり本発明には相当しない）。
The length and weight of the carbon nanotubes obtained each time the CVD method was performed and variations thereof were determined in the same manner as in Example 1. These measurement results are shown in FIGS. FIG. 10 shows that the variation in the length and weight of the carbon nanotube can be suppressed to 10% or less when the heat treatment time is 10 minutes or more. As is apparent from FIG. 10, even when the heating time is 60 minutes, the degree of variation remains small, but it is not necessary to heat for a long time from the viewpoint of cost (the
Claims (1)
前記触媒金属薄膜の金属を微粒化する工程と、
前記触媒金属の微粒子を核として基板上にカーボンナノチューブを形成する工程を含むカーボンナノチューブの生成方法において、
前記触媒金属薄膜の金属を微粒化する工程を、５〜１５％の酸素雰囲気中で７００℃以上〜９００℃未満での１０〜６０分間の加熱により行うことを特徴とする
カーボンナノチューブの生成方法。 Forming a catalyst metals thin film composed of Fe on a substrate,
Atomizing the metal of the catalyst metal thin film;
In the method for producing carbon nanotubes, comprising the step of forming carbon nanotubes on a substrate with the catalyst metal fine particles as nuclei,
A method of producing carbon nanotubes, wherein the step of atomizing the metal of the catalyst metal thin film is performed by heating at 700 ° C. or more and less than 900 ° C. for 10 to 60 minutes in a 5 to 15% oxygen atmosphere.
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