JP2005213104A - Method of forming highly oriented carbon nanotube and apparatus suitable for forming highly oriented carbon nanotube - Google Patents
Method of forming highly oriented carbon nanotube and apparatus suitable for forming highly oriented carbon nanotube Download PDFInfo
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本発明は、プラズマ化学気相蒸着法により高配向カーボンナノチューブを生成させる方法、及び高配向カーボンナノチューブの生成に適した生成装置に関する。 The present invention relates to a method for generating highly aligned carbon nanotubes by plasma enhanced chemical vapor deposition and a generator suitable for generating highly aligned carbon nanotubes.
カーボンナノチューブ（以下、「ＣＮＴ」という。）は、柔軟であり引張り強度も強く、優れた機械的特性を持つため、多方面での産業的利用が期待されている。このＣＮＴは、アーク放電法、レーザー蒸発法、又はプラズマ化学気相蒸着法（以下、「プラズマＣＶＤ法」という。）等の方法によって生成可能である。なかでもプラズマＣＶＤ法は、用途に応じて、基板の面に生成されるＣＮＴの直径、長さ、又は成長の方向といった形状の制御が可能であるといった点において、期待されている（特許文献１参照）。 Carbon nanotubes (hereinafter referred to as “CNT”) are flexible, have high tensile strength, and have excellent mechanical properties, and thus are expected to be industrially used in various fields. The CNT can be generated by a method such as an arc discharge method, a laser evaporation method, or a plasma chemical vapor deposition method (hereinafter referred to as “plasma CVD method”). Among these, the plasma CVD method is expected in that the shape such as the diameter, length, or growth direction of the CNT generated on the surface of the substrate can be controlled according to the application (Patent Document 1). reference).
プラズマＣＶＤ法は、水素プラズマ処理を用いたプラズマＣＶＤ法、通電加熱を用いたプラズマＣＶＤ法、又はマッフル炉を用いたマイクロ波プラズマＣＶＤ法が代表的である。これらの方法による基板へのＣＮＴの生成はいずれも、減圧されたチャンバー内に基板を配置し、基板を所定の温度まで加熱してプラズマ暴露するとともに、炭素含有ガスをチャンバー内に供給することによって行われる。なお、プラズマＣＶＤ法によって基板にＣＮＴを生成させるには、ＣＮＴを生成させようとする基板の面に触媒金属が必要である。 The plasma CVD method is typically a plasma CVD method using hydrogen plasma treatment, a plasma CVD method using current heating, or a microwave plasma CVD method using a muffle furnace. In any of these methods, CNTs are generated on a substrate by placing the substrate in a decompressed chamber, heating the substrate to a predetermined temperature and exposing it to plasma, and supplying a carbon-containing gas into the chamber. Done. In order to generate CNTs on a substrate by plasma CVD, a catalytic metal is required on the surface of the substrate on which CNTs are to be generated.
ところが、プラズマＣＶＤ法により基板の面にＣＮＴを生成する場合、基板の面にＣＮＴが生成される過程でＣＮＴの生成に寄与しないプラズマ電子が、すでに基板の面に生成されているＣＮＴに衝撃を与え、ＣＮＴの先端構造を破壊してしまう。その結果、ＣＮＴの成長が抑制され、高配向ＣＮＴ（直立形状ＣＮＴ）が生成されにくいといった問題がある。 However, when generating CNTs on the surface of the substrate by plasma CVD, plasma electrons that do not contribute to the generation of CNTs in the process of generating CNTs on the surface of the substrate impact the CNTs already generated on the surface of the substrate. And destroys the tip structure of the CNT. As a result, there is a problem that the growth of CNTs is suppressed and highly oriented CNTs (upright CNTs) are difficult to be generated.
本発明は、上記問題点に鑑みてなされたものであって、プラズマＣＶＤ法により高配向ＣＮＴを生成させる方法を提供することを第１の目的とする。
そして、プラズマＣＶＤ法により高配向ＣＮＴの生成に適した生成装置の提供も目的とする。
This invention is made | formed in view of the said problem, Comprising: It aims at providing the method of producing | generating highly oriented CNT by plasma CVD method.
Another object of the present invention is to provide a generating apparatus suitable for generating highly oriented CNTs by plasma CVD.
本発明において、以下の特徴は単独で、若しくは、適宜組合わされて備えられている。前記課題を解決するための本発明に係るＣＮＴの生成方法は、プラズマＣＶＤ法によりカーボンナノチューブを基板に生成させるカーボンナノチューブの生成方法であって、Ｆｅ，Ｃｏ，Ｎｉ，Ｇａ，Ｉｎ（ＩＴＯ），Ａｌ，Ｓｎの少なくともいずれかの金属を含む触媒を前記基板の面に付着させる第１の工程と、前記第１の工程で得られた基板が配置されたチャンバーの内部に、炭素含有ガスを供給するとともにプラズマ電子を発生させる第２の工程と、を有し、前記第２の工程が、前記チャンバーの内部に発生させるプラズマ電子が前記基板に直射しないように遮蔽する工程を有することを特徴とする。 In the present invention, the following features are provided alone or in combination as appropriate. A method for producing CNTs according to the present invention for solving the above-described problem is a method for producing carbon nanotubes by producing carbon nanotubes on a substrate by plasma CVD, and includes Fe, Co, Ni, Ga, In (ITO), A first step of depositing a catalyst containing at least one of Al and Sn on the surface of the substrate, and supplying a carbon-containing gas into the chamber in which the substrate obtained in the first step is disposed. And a second step of generating plasma electrons, wherein the second step includes a step of shielding the plasma electrons generated inside the chamber from direct irradiation to the substrate. To do.
これによれば、チャンバーの内部に発生させるプラズマ電子が基板に直射しないように遮蔽してプラズマ電子を発生させているので、基板に向かうプラズマ電子の減速、又はその数が減少すると考えられる。その結果、すでに基板の面に生成されたＣＮＴの先端構造に与える衝撃が軽減され、当該ＣＮＴの先端構造の破壊が抑制される。このようにして、ＣＮＴの成長速度が従来のプラズマＣＶＤ法を用いた場合に比べて速くなり、高配向ＣＮＴが生成され易くなると考えられる。 According to this, since the plasma electrons generated inside the chamber are shielded so that they do not directly irradiate the substrate, the plasma electrons are generated, so that it is considered that the deceleration or the number of plasma electrons toward the substrate decreases. As a result, the impact on the tip structure of the CNT already generated on the surface of the substrate is reduced, and the destruction of the tip structure of the CNT is suppressed. In this way, it is considered that the growth rate of CNTs becomes faster than when the conventional plasma CVD method is used, and highly oriented CNTs are easily generated.
なお、ここで「Ｆｅ，Ｃｏ，Ｎｉ，Ｇａ，Ｉｎ（ＩＴＯ），Ａｌ，Ｓｎの少なくともいずれかの金属を含む触媒」とは、これらの金属の少なくともいずれかの金属のみからなる触媒、これらの金属のいずれか複数の金属からなる触媒、これらの金属の少なくともいずれかの金属を含む化合物からなる触媒、又はこれらの金属の少なくともいずれかの金属を含む酸化物を含む触媒、などを意味する。また、これらの金属のイオンであってもよい。 Here, “a catalyst containing at least one of Fe, Co, Ni, Ga, In (ITO), Al, and Sn” refers to a catalyst made of only at least one of these metals, It means a catalyst composed of any one of a plurality of metals, a catalyst composed of a compound containing at least one of these metals, or a catalyst containing an oxide containing at least one of these metals. Moreover, the ion of these metals may be sufficient.
また、本発明に係るＣＮＴの生成方法は、前記第１の工程が、１００ｎｍ未満の触媒の微粒子を、前記基板の面に形成させるものであることが好ましい。 In the CNT production method according to the present invention, it is preferable that the first step is to form catalyst fine particles of less than 100 nm on the surface of the substrate.
これによれば、１００ｎｍ未満の触媒の微粒子が面に形成された基板にＣＮＴを生成させるので、先端に１００ｎｍ未満の触媒金属微粒子を包含するＣＮＴを、基板の面からウィスカー状に生成させることが可能となる。 According to this, since CNT is generated on the substrate on which the catalyst fine particles of less than 100 nm are formed on the surface, the CNT including the catalyst metal fine particles of less than 100 nm at the tip can be generated in the form of whiskers from the surface of the substrate. It becomes possible.
また、本発明に係るＣＮＴの生成方法は、前記第１の工程が、イオン描画法によって、１００ｎｍ未満の触媒の微粒子を前記基板の面に形成させることが好ましい。 In the method for producing CNTs according to the present invention, it is preferable that the first step forms catalyst fine particles of less than 100 nm on the surface of the substrate by an ion drawing method.
これによれば、１００ｎｍ未満の触媒の微粒子を、整然とパターニングして基板の面に直接描画することができるので、そのパターニング通りのＣＮＴを基板の面に生成させることができる。 According to this, fine particles of the catalyst of less than 100 nm can be orderly patterned and drawn directly on the surface of the substrate, so that CNTs as patterned can be generated on the surface of the substrate.
また、本発明に係るＣＮＴの生成方法は、ＳｉＯ2が前記基板の面に形成され、前記第１の工程が、自己成長法によって、１００ｎｍ未満の触媒の微粒子を前記基板の面に形成させることが好ましい。 In the method for producing CNTs according to the present invention, SiO 2 is formed on the surface of the substrate, and the first step is to form fine particles of a catalyst of less than 100 nm on the surface of the substrate by a self-growth method. Is preferred.
基板の面に１００ｎｍ未満の触媒の微粒子を形成させる場合、基板の面に触媒を自己成長法で規則的に微細ドットを自己成長配列させる観点から、基板の面にはＳｉＯ2膜が形成されていることが好ましい。触媒金属を、ＳｉＯ2膜が形成されていない基板の面に真空蒸着法等で形成させ、水素ガス等の還元雰囲気中で７００℃に加熱すると、触媒金属が溶融して島状に不定形に凝集してしまう。その結果、自己成長した規則的な微細ドットを基板の面に自己成長配列させることができない。そこで、基板の面にＳｉＯ2膜を形成させてから、面に触媒金属を真空蒸着法等で形成させ、水素ガス等の還元雰囲気中で７００℃に加熱すると、触媒金属が溶融して規則的な配列に自己成長し、１００ｎｍ未満の触媒金属微粒子をドット状に規則的に整列させることが可能となる。 In the case of forming catalyst fine particles of less than 100 nm on the surface of the substrate, an SiO 2 film is formed on the surface of the substrate from the viewpoint of regularly arranging fine dots on the surface of the substrate by the self-growth method. Preferably it is. When the catalyst metal is formed on the surface of the substrate on which the SiO 2 film is not formed by a vacuum deposition method or the like and heated to 700 ° C. in a reducing atmosphere such as hydrogen gas, the catalyst metal is melted into an island-like shape. Aggregates. As a result, the self-grown regular fine dots cannot be self-grown on the surface of the substrate. Therefore, after the SiO 2 film is formed on the surface of the substrate, the catalyst metal is formed on the surface by a vacuum deposition method or the like, and heated to 700 ° C. in a reducing atmosphere such as hydrogen gas, the catalyst metal is melted and ordered. It is possible to self-grow in a uniform arrangement and regularly arrange catalyst metal fine particles of less than 100 nm in a dot shape.
また、本発明に係る基板は、上記方法によって、先端に１００ｎｍ未満の触媒金属微粒子を包含したＣＮＴが、面に生成されたものが好ましい。 In addition, the substrate according to the present invention is preferably such that CNTs containing catalytic metal fine particles of less than 100 nm at the tip are generated on the surface by the above method.
先端に金属微粒子を包含するウィスカーブラシは摩擦係数が非常に小さいため、上記方法によって得られた基板は、ＭＥＭＳの摺動部に使えることが期待できる。また、ＣＮＴトランジスターとナノサイズ磁気記憶媒体が結合した不揮発メモリー内臓半導体デバイスの誕生も期待できる。 Since the whisker brush containing metal fine particles at the tip has a very small friction coefficient, it can be expected that the substrate obtained by the above method can be used for the sliding portion of the MEMS. In addition, a semiconductor device with a built-in nonvolatile memory in which a CNT transistor and a nano-sized magnetic storage medium are combined can be expected.
また、本発明の係るＣＮＴの生成装置は、基板が配置されたチャンバーの内部に炭素含有ガスを供給し、プラズマＣＶＤ法により前記基板の面にカーボンナノチューブを生成させるカーボンナノチューブの生成装置であって、前記チャンバーの内部に配置され、前記基板を保持可能な基板保持部と、前記チャンバー内にプラズマ電子を発生させるマイクロ波発生部と、前記基板保持部と前記マイクロ波発生部との間に、前記マイクロ波発生部から発生するプラズマ電子の前記基板への直射を遮る遮蔽部材と、を備えることを特徴とする。 The CNT generation apparatus according to the present invention is a carbon nanotube generation apparatus that supplies a carbon-containing gas into a chamber in which a substrate is disposed, and generates carbon nanotubes on the surface of the substrate by a plasma CVD method. A substrate holding unit disposed inside the chamber and capable of holding the substrate, a microwave generating unit for generating plasma electrons in the chamber, and between the substrate holding unit and the microwave generating unit, And a shielding member that blocks direct irradiation of plasma electrons generated from the microwave generation unit onto the substrate.
これによれば、マイクロ波発生部から発生するプラズマ電子の基板への直射が、遮蔽部材によって遮られるので、基板に向かうプラズマ電子の減速、又はその数が減少すると考えられる。その結果、すでに基板の面に生成されたＣＮＴの先端構造にプラズマ電子が与える衝撃が軽減され、当該ＣＮＴの先端構造の破壊が抑制される。このようにして、ＣＮＴの成長速度が従来のプラズマＣＶＤ法を用いた場合に比べて速くなり、高配向ＣＮＴの生成に適したＣＮＴの生成装置の提供が可能となる。 According to this, since direct irradiation of the plasma electrons generated from the microwave generation part onto the substrate is blocked by the shielding member, it is considered that the deceleration of the plasma electrons toward the substrate or the number thereof decreases. As a result, the impact of plasma electrons on the tip structure of the CNT already generated on the surface of the substrate is reduced, and destruction of the tip structure of the CNT is suppressed. In this way, the growth rate of CNTs is faster than when the conventional plasma CVD method is used, and it is possible to provide a CNT generation apparatus suitable for generating highly oriented CNTs.
以下、本発明に係るプラズマＤＶＤ法による高配向ＣＮＴを生成させる方法、及びプラズマＤＶＤ法による高配向ＣＮＴの生成に適した生成装置の例について、以下に説明する。 Hereinafter, an example of a method for generating highly aligned CNTs by the plasma DVD method according to the present invention and a generation apparatus suitable for generating highly aligned CNTs by the plasma DVD method will be described.
先ず、本発明に係るプラズマＤＶＤ法による高配向ＣＮＴの生成に適した生成装置について、図１を用いて説明する。ここで、図１は、マイクロ波プラズマＣＶＤ装置１の概略図である。 First, a generating apparatus suitable for generating highly oriented CNTs by the plasma DVD method according to the present invention will be described with reference to FIG. Here, FIG. 1 is a schematic view of a microwave plasma CVD apparatus 1.
図１に図示されるマイクロ波プラズマＣＶＤ装置１は、チャンバー２と、炭素含有ガス供給部３と、加熱装置４と、基板保持部５と、マイクロ波発生部６と、遮蔽部材７とを備えている。 A microwave plasma CVD apparatus 1 illustrated in FIG. 1 includes a chamber 2, a carbon-containing gas supply unit 3, a heating device 4, a substrate holding unit 5, a microwave generation unit 6, and a shielding member 7. ing.
チャンバー２は、本実施形態では石英管を使用し、一端２ａには炭素含有ガス供給部３が設けられ、他端２ｂにはチャンバー２内の真空引きを行うためのロータリーポンプ８が接続されている。なお、チャンバー２の両端２ａ・２ｂは、内部の真空度を保持できる様、密封されている。 The chamber 2 uses a quartz tube in this embodiment, and is provided with a carbon-containing gas supply unit 3 at one end 2a, and a rotary pump 8 for evacuating the chamber 2 is connected to the other end 2b. Yes. In addition, both ends 2a and 2b of the chamber 2 are sealed so that the degree of internal vacuum can be maintained.
炭素含有ガス供給部３は、Ｈ2のボンベとＣＨ4のボンベに接続されており、これらのボンベに選択的に切り替えて、いずれのガスもチャンバー２内に供給可能な構成となっている。 The carbon-containing gas supply unit 3 is connected to an H 2 cylinder and a CH 4 cylinder, and can be selectively switched to these cylinders to supply any gas into the chamber 2.
基板保持部５は、基板１０をチャンバー２内に保持できるように、チャンバー２内に配置されている。 The substrate holding unit 5 is disposed in the chamber 2 so that the substrate 10 can be held in the chamber 2.
マイクロ波発生部６は、発振周波数２．４５ＧＨｚ、最大出力５００Ｗのマグネトロン９をマイクロ波源として用いており、炭素含有ガス供給部３と基板保持部５との間に配置されている。そして、基板１０に−５００Ｖのバイアス電圧を印加することでチャンバー２内にマイクロ波プラズマ電子を発生させることが可能な構成となっている。 The microwave generation unit 6 uses a magnetron 9 having an oscillation frequency of 2.45 GHz and a maximum output of 500 W as a microwave source, and is disposed between the carbon-containing gas supply unit 3 and the substrate holding unit 5. Then, by applying a bias voltage of −500 V to the substrate 10, microwave plasma electrons can be generated in the chamber 2.
遮蔽部材７は、板状の部材であって、基板保持部５とマイクロ波発生部６との間に備えられている。そして、電子プラズマの進行方向（即ち、マイクロ波発生部６）と対向する基板１０の表面積全部を覆うように構成されることが好ましい。この遮蔽部材７は、マイクロ波発生部６から発生するプラズマ電子が、基板保持部５に保持された基板１０に直射することを防止している。このように遮蔽部材７を設けることで、基板１０に向かうプラズマ電子の速度の減速、又はその数が減少すると考えられるので、すでに基板１０の表面に生成されたＣＮＴの先端構造にプラズマ電子が与える衝撃が軽減され、当該ＣＮＴの先端構造の破壊が抑制される。 The shielding member 7 is a plate-like member and is provided between the substrate holding unit 5 and the microwave generation unit 6. And it is preferable to be comprised so that the whole surface area of the board | substrate 10 which opposes the advancing direction (namely, microwave generation part 6) of electron plasma may be covered. The shielding member 7 prevents plasma electrons generated from the microwave generator 6 from directly irradiating the substrate 10 held by the substrate holder 5. By providing the shielding member 7 in this manner, it is considered that the speed of the plasma electrons toward the substrate 10 is reduced or the number thereof is reduced, so that plasma electrons are given to the tip structure of the CNT already generated on the surface of the substrate 10. The impact is reduced and the destruction of the tip structure of the CNT is suppressed.
なお、この遮蔽部材７の材質は、金属、半導体、絶縁体の何れでも可能である。また、遮蔽部材７は、マイクロ波発生部６と基板保持部５との間を完全に仕切るものではなく、マイクロ波発生部６から発生した電子が、チャンバー２の内壁と遮蔽部材７との間を通過可能な程度の隙間が必要である。 The material of the shielding member 7 can be any of metal, semiconductor, and insulator. Further, the shielding member 7 does not completely separate the microwave generation unit 6 and the substrate holding unit 5, and the electrons generated from the microwave generation unit 6 are between the inner wall of the chamber 2 and the shielding member 7. A gap that can pass through is required.
ここで、基板１０又はチャンバー２との関係における遮蔽部材７の配置位置、及び遮蔽部材７の形状として、例えば図２（ａ）〜（ｅ）に図示されるようなものが考えられる。なお、図２に図示される矢印は、基板１０に向かう電子プラズマの進行方法を示している。図２（ａ）〜（ｅ）に図示されるように、遮蔽部材７は、いずれも電子プラズマの進行方向と対向する基板１０の表面積全部を覆っている。 Here, as the arrangement position of the shielding member 7 in relation to the substrate 10 or the chamber 2 and the shape of the shielding member 7, for example, the ones shown in FIGS. 2A to 2E can be considered. Note that the arrows shown in FIG. 2 indicate the method of advancing electron plasma toward the substrate 10. As shown in FIGS. 2A to 2E, the shielding member 7 covers the entire surface area of the substrate 10 facing the traveling direction of the electron plasma.
具体的に、図２（ａ）に図示される遮蔽部材７は１枚の板状部材から成り、電子プラズマの基板１０への直射を遮るように、その面が電子プラズマの進行方向に対して対向して配置されている。電子プラズマの基板１０への直射を遮るといった観点において、最も簡便な構成である。 Specifically, the shielding member 7 shown in FIG. 2 (a) is composed of a single plate-like member, and the surface of the shielding member 7 with respect to the traveling direction of the electron plasma is shielded from direct irradiation of the electron plasma onto the substrate 10. Opposed to each other. This is the simplest configuration from the viewpoint of blocking direct irradiation of the electron plasma onto the substrate 10.
図２（ｂ）に図示される遮蔽部材７は、３枚の板状部材を電子プラズマの進行方向にずらして配置されるとともに、それら各々の板状部材の面がプラズマ電子の進行方向に重なるように配置されている。このような構成であっても、電子プラズマの基板１０への直射を遮ることができる。 The shielding member 7 shown in FIG. 2B is arranged by shifting the three plate-like members in the direction of travel of the electron plasma, and the surface of each plate-like member overlaps the direction of travel of the plasma electrons. Are arranged as follows. Even with such a configuration, direct irradiation of the electron plasma onto the substrate 10 can be blocked.
図２（ｃ）に図示される遮蔽部材７は、ピンホール状の小さな孔を多数有する１枚の板状部材からなるものである。これによれば、１枚の板状部材を配置するのみという簡便な構成で、電子プラズマの基板１０への直射を遮ることができる。 The shielding member 7 illustrated in FIG. 2C is made of a single plate-like member having many pinhole-like small holes. According to this, direct irradiation of the electron plasma onto the substrate 10 can be blocked with a simple configuration in which only one plate-like member is arranged.
図２（ｄ）に図示される遮蔽部材７は、１枚の板状部材を湾曲させた凸面と凹面を有した湾曲部材であり、凸面が電子プラズマの進行方向に対向するように配置されている。このような構成であっても、電子プラズマの基板１０への直射を遮ることができる。 The shielding member 7 shown in FIG. 2 (d) is a curved member having a convex surface and a concave surface obtained by bending one plate-like member, and is arranged so that the convex surface faces the traveling direction of the electron plasma. Yes. Even with such a configuration, direct irradiation of the electron plasma onto the substrate 10 can be blocked.
図２（ｅ）に図示される遮蔽部材７は、２枚の板状部材からなるものであって、それらを電子プラズマの進行方向にずらして配置されるとともに、各々の板状部材の面がプラズマ電子の進行方向に重なるように配置され、さらにチャンバー２が遮蔽部材７を回避するように径外側に突出している。これによれば、基板１０の表面積が多少大きくなっても、電子プラズマの基板１０への直射を遮ることができる。 The shielding member 7 shown in FIG. 2 (e) is composed of two plate-like members, which are arranged by shifting them in the direction of travel of the electron plasma, and the surface of each plate-like member is It arrange | positions so that it may overlap with the advancing direction of a plasma electron, Furthermore, the chamber 2 protrudes on the diameter outer side so that the shielding member 7 may be avoided. According to this, even if the surface area of the substrate 10 is somewhat increased, direct irradiation of the electron plasma onto the substrate 10 can be blocked.
なお、遮蔽部材７の形状や配置方法は図２（ａ）〜（ｅ）の各構成を適宜組み合わせた構成であってもよい。また、図２（ａ）〜（ｅ）に図示される遮蔽部材７は例として列挙したにすぎず、電子プラズマの基板１０への直射を遮ることによって基板１０の表面に高配向ＣＮＴを生成させることができれば、形状、及び配置方法はこれらに限られるものではない。 In addition, the structure which combined suitably each structure of Fig.2 (a)-(e) may be sufficient as the shape and arrangement | positioning method of the shielding member 7. FIG. Moreover, the shielding member 7 illustrated in FIGS. 2A to 2E is only listed as an example, and highly oriented CNTs are generated on the surface of the substrate 10 by blocking direct irradiation of the electron plasma onto the substrate 10. If possible, the shape and the arrangement method are not limited to these.
本実施形態においては、チャンバー２として石英管を用いたが、内部の真空引きが可能であって、かつ７００℃程度の高温に耐え得るものであれば石英管に限られるものではない。 In this embodiment, a quartz tube is used as the chamber 2. However, the chamber is not limited to a quartz tube as long as the inside can be evacuated and can withstand a high temperature of about 700 ° C.
また、炭素含有ガス供給部３は、Ｈ2のボンベとＣＨ4のボンベに接続されるものに限られず、ＣＨ4の替わりにメタン（ＣＨ4）、アセチレン（Ｃ2Ｈ2）、一炭化酸素（ＣＯ）、ベンゼン（Ｃ6Ｈ6）、エチレン（Ｃ2Ｈ4）、エタノール（ＣＨ3ＣＨ2ＯＨ）のボンベに接続されるものであってもよい。即ち、炭素Ｃが含有されているガスボンベに接続されていればよい。なお、これらのガスをチャンバー２内に供給できるのであれば、必ずしもこれらのガスが充填されたボンベに接続する必要もなく、例えば、これらのガスの製造プラントから配管を通じて直接供給されるような態様であってもよい。 Further, the carbon-containing gas supply unit 3 is not limited to being connected to a cylinder of H 2 gas cylinder and CH 4, methane (CH 4) in place of CH 4, acetylene (C 2 H 2), one carbide oxygen It may be connected to a cylinder of (CO), benzene (C 6 H 6 ), ethylene (C 2 H 4 ), ethanol (CH 3 CH 2 OH). In other words, it may be connected to a gas cylinder containing carbon C. In addition, if these gases can be supplied into the chamber 2, it is not always necessary to connect to a cylinder filled with these gases. For example, an embodiment in which these gases are directly supplied from a production plant through piping. It may be.
次に、本発明に係るプラズマＤＶＤ法による高配向ＣＮＴを生成させる方法について説明する。 Next, a method for generating highly oriented CNTs by the plasma DVD method according to the present invention will be described.
本実施形態では、プラズマＣＶＤ法を用いて基板１０にＣＮＴを生成させており、基板１０の表面に触媒金属微粒子を付着させる第１の工程と、第１の工程で得られた基板１０の表面にプラズマＣＶＤ法によってＣＮＴを生成させる工程とを有している。 In the present embodiment, the CNTs are generated on the substrate 10 by using the plasma CVD method, and the surface of the substrate 10 obtained in the first step is obtained by attaching the catalytic metal fine particles to the surface of the substrate 10. And a step of generating CNTs by a plasma CVD method.
なお、基板１０が長時間大気に暴露されていた場合などには、基板１０の表面に吸着物や不純物ならびに酸化層が存在していると考えられるので、第１の工程の予備処理として、基板１０の洗浄処理が必要である。 When the substrate 10 has been exposed to the atmosphere for a long time, it is considered that adsorbates, impurities, and oxide layers are present on the surface of the substrate 10. Ten cleaning processes are required.
（触媒金属微粒子付着処理工程）
基板１０の表面に触媒金属微粒子を付着させる工程には、２通りの方法が考えられる。第１の方法として考えられるのが触媒金属のイオン描画法、第２の方法として考えられるのが触媒金属の自己成長法である。
(Catalyst metal fine particle adhesion treatment process)
There are two possible methods for attaching the catalytic metal fine particles to the surface of the substrate 10. The first method may be an ion drawing method of a catalytic metal, and the second method may be a catalytic metal self-growth method.
第１の方法である触媒金属のイオン描画法は、真空中で触媒金属のイオンを直接基板１０に照射する方法である。この方法によって、ナノサイズの触媒金属イオンを、基板１０の表面にドット状に整列させるように描画することができる。その後、触媒金属のイオンが描画された基板１０の加熱処理を行うことで、基板１０の表面に触媒金属イオンの描画パターンを定着させることができる。この加熱処理は、１００％Ｈ2雰囲気中で、基板１０の温度が６００℃〜９００℃、加熱時間が５分〜６０分の範囲で行うとよい。なお、イオン描画法による基板１０への触媒金属のイオン描画は、一般に市販されている公知のイオン描画装置を用いて行うことが可能であり、基板１０にはＳｉ基板を用いるのが好ましい。 The catalyst metal ion drawing method, which is the first method, is a method of directly irradiating the substrate 10 with catalyst metal ions in a vacuum. By this method, nano-sized catalytic metal ions can be drawn so as to be aligned in a dot shape on the surface of the substrate 10. Thereafter, the substrate 10 on which the catalyst metal ions are drawn is subjected to heat treatment, whereby the drawing pattern of the catalyst metal ions can be fixed on the surface of the substrate 10. This heat treatment is preferably performed in a 100% H 2 atmosphere at a temperature of the substrate 10 of 600 ° C. to 900 ° C. and a heating time of 5 minutes to 60 minutes. In addition, ion drawing of the catalytic metal on the substrate 10 by the ion drawing method can be performed using a publicly-known ion drawing apparatus that is generally commercially available, and the substrate 10 is preferably a Si substrate.
第２の方法である触媒金属の自己成長法は、先ず、Ｓｉ基板１０の表面にＳｉＯ2薄膜を形成させたのちに触媒金属を真空蒸着させる。このように得られた基板１０を加熱処理すると、基板１０の表面に蒸着された触媒金属が自己成長し、ナノサイズのドット状に整列する。この加熱処理は、１００％Ｈ2雰囲気中で、基板１０の温度が６００℃〜９００℃の範囲で、５分〜６０分の間で行うとよい。 In the catalyst metal self-growth method, which is the second method, first, an SiO 2 thin film is formed on the surface of the Si substrate 10 and then the catalyst metal is vacuum-deposited. When the substrate 10 thus obtained is heat-treated, the catalytic metal deposited on the surface of the substrate 10 self-grows and is aligned in the form of nano-sized dots. This heat treatment is preferably performed in a 100% H 2 atmosphere at a temperature of the substrate 10 in the range of 600 ° C. to 900 ° C. for 5 minutes to 60 minutes.
なお、触媒金属として代表的なものはＦｅであるが、Ｆｅの他、Ｎｉ，Ｃｏ，Ｇａ，Ｉｎ（ＩＴＯ），Ａｌ，Ｓｎについても触媒金属として効果があることが知られている。さらに、これらの金属を含む化合物、又は酸化物であってもよい。例えばＦｅであれば、純鉄以外にフェロセン（Ｃ5Ｈ5）２Ｆｅ，酸化鉄（Ｆｅ2Ｏ3），Ｆｅ（ＣＯ）5，硝酸鉄（Ｆｅ（ＮＯ3）3）であってもよい。 A typical catalyst metal is Fe, but Ni, Co, Ga, In (ITO), Al, and Sn are known to be effective as catalyst metals in addition to Fe. Further, it may be a compound or oxide containing these metals. For example, in the case of Fe, ferrocene (C 5 H 5 ) 2 Fe, iron oxide (Fe 2 O 3 ), Fe (CO) 5 , and iron nitrate (Fe (NO 3 ) 3 ) may be used in addition to pure iron.
（ＣＮＴ生成工程）
ＣＮＴ生成工程は、触媒金属微粒子付着処理工程で表面に触媒金属微粒子が付着した基板１０にＣＮＴを生成させる工程である。なお、ＣＮＴの生成は、基板１０の面に生成されるＣＮＴの直径、長さ、又は成長の方向といった形状の制御が可能であるといった観点から、プラズマＣＶＤ法によって行う。
(CNT production process)
The CNT generation step is a step of generating CNTs on the substrate 10 having the catalyst metal fine particles attached to the surface in the catalyst metal fine particle attachment treatment step. Note that CNTs are generated by a plasma CVD method from the viewpoint that the shape, such as the diameter, length, or growth direction of the CNTs generated on the surface of the substrate 10 can be controlled.
ここでは、プラズマＣＶＤ法によるＣＮＴ生成工程について、図１に図示されるマイクロ波プラズマＣＶＤ装置１を用いて説明する。 Here, the CNT production | generation process by plasma CVD method is demonstrated using the microwave plasma CVD apparatus 1 illustrated in FIG.
先ず、表面に触媒金属の微粒子が付着した基板１０を、基板保持部５に保持する。そして、基板１０が内部に配置されたチャンバー２を密封し、チャンバー２内の圧力が１０Ｐａ〜１０，０００Ｐａの範囲となる様、ロータリーポンプ８で減圧する。 First, the substrate 10 having catalyst metal fine particles attached to the surface is held by the substrate holding unit 5. And the chamber 2 in which the board | substrate 10 is arrange | positioned is sealed, and it pressure-reduces with the rotary pump 8 so that the pressure in the chamber 2 may become the range of 10 Pa-10,000 Pa.
そして、基板１０の温度を５００℃〜８００℃の範囲で保ち、炭素含有ガス供給部３からチャンバー２内に炭素含有ガスの供給を行うとともに、基板１０にバイアス電圧を−５０Ｖ〜−６００Ｖの範囲で印加しながら、マイクロ波プラズマＣＶＤを行い、基板１０の表面にＣＮＴを生成させる。 And while keeping the temperature of the board | substrate 10 in the range of 500 to 800 degreeC, while supplying carbon-containing gas in the chamber 2 from the carbon-containing gas supply part 3, the bias voltage is applied to the board | substrate 10 in the range of -50V--600V. While applying the above, microwave plasma CVD is performed to generate CNTs on the surface of the substrate 10.
なお、炭素含有ガスとして考えられる代表的なガスはメタン（ＣＨ4）であるが、メタン（ＣＨ4）の他、アセチレン（Ｃ2Ｈ2）、一炭化酸素（ＣＯ）、ベンゼン（Ｃ6Ｈ6）、エチレン（Ｃ2Ｈ4）、エタノール（ＣＨ3ＣＨ2ＯＨ）であってもよい。即ち、炭素Ｃが含有されているガスであれば、基板１０の表面にＣＮＴを生成させることが可能である。 A typical gas considered as a carbon-containing gas is methane (CH 4 ), but in addition to methane (CH 4 ), acetylene (C 2 H 2 ), monocarbon oxygen (CO), benzene (C 6 H) 6 ), ethylene (C 2 H 4 ), ethanol (CH 3 CH 2 OH). That is, if the gas contains carbon C, it is possible to generate CNTs on the surface of the substrate 10.
また、本実施形態では、基板保持部５とマイクロ波発生部６との間に遮蔽部材７が設けられているため、マイクロ波発生部６から発生したプラズマ電子が基板１０の表面に直射しないように遮蔽してプラズマＣＶＤが行われている。 In the present embodiment, since the shielding member 7 is provided between the substrate holding unit 5 and the microwave generation unit 6, plasma electrons generated from the microwave generation unit 6 do not directly hit the surface of the substrate 10. Plasma CVD is performed while shielding.
このように、基板１０に直射しないように遮蔽してチャンバー２の内部にプラズマ電子を発生させる工程を有することで、すでに基板１０の面に生成されたＣＮＴの先端構造に対してプラズマ電子が与える衝撃が軽減され、ＣＮＴの先端構造の破壊が抑制される。その結果、ＣＮＴの成長速度が、遮蔽部材７を設けずにプラズマＣＶＤを行った場合に比べて速くなり、高配向ＣＮＴの薄膜が生成され易くなる。 As described above, the plasma electron is given to the tip structure of the CNT already generated on the surface of the substrate 10 by including the step of generating plasma electrons inside the chamber 2 by shielding the substrate 10 from direct irradiation. The impact is reduced and the destruction of the tip structure of the CNT is suppressed. As a result, the growth rate of CNTs is faster than when plasma CVD is performed without providing the shielding member 7, and a highly oriented CNT thin film is easily generated.
また、本実施形態では、基板１０の表面に金属微粒子を付着させている。触媒金属の微粒子は、ＳｉＯ2薄膜が形成された部分の面に自己成長して整列するので、金属微粒子を基板１０の表面にパターニング形成させることで、所望のパターンでＣＮＴを生成させることができる。 In this embodiment, metal fine particles are attached to the surface of the substrate 10. Since the catalytic metal fine particles self-grow and align on the surface of the portion where the SiO 2 thin film is formed, the CNTs can be generated in a desired pattern by patterning the metal fine particles on the surface of the substrate 10. .
また、基板１０の表面に金属微粒子を付着させると、金属微粒子と基板１０との間からＣＮＴがウイスカー状に生成される。このように、ウイスカー状に生成された直立形状ＣＮＴの先端にはナノサイズの金属微粒子が包含されることとなる。とくに、基板１０の表面に鉄系金属の微粒子を付着させると、先端に磁気特性を持つ鉄系金属微粒子を包含したＣＮＴがウィスカー状に生成されるので、ＣＮＴと鉄系金属の磁気特性が得られる新しいナノ材料の誕生が期待できる。 Further, when metal fine particles are attached to the surface of the substrate 10, CNTs are generated in a whisker shape from between the metal fine particles and the substrate 10. In this way, nano-sized fine metal particles are included at the tips of the upright CNTs generated in the form of whiskers. In particular, when iron-based metal fine particles are attached to the surface of the substrate 10, CNTs containing iron-based metal fine particles having magnetic properties at the tip are formed in a whisker shape, so that the magnetic properties of CNT and iron-based metal are obtained. The birth of new nanomaterials can be expected.
なお、Ｓｉ基板の表面に磁気特性を持つ鉄系金属、又はこの鉄系金属のイオンを含む１００ｎｍ未満の触媒金属微粒子を付着させたのち、このＳｉ基板の表面にプラズマＣＶＤ法によりＣＮＴを生成させる場合には、マイクロ波発生部６から発生したプラズマ電子がこのＳｉ基板の表面に直射しないようにすることは必ずしも必須の要件ではない。例えば、Ｓｉ基板の表面に高配向ＣＮＴを生成できる他の方法が存在する場合には、当該他の方法で生成させたＣＮＴの先端にも磁性特性を持つ触媒金属微粒子が包含されることとなり、新しいナノ材料の誕生が期待できることに変わりない。即ち、プラズマＤＶＤ法によりＳｉ基板にＣＮＴを生成させる方法であって、磁気特性を持つ鉄系金属、又はこの鉄系金属のイオンを含む１００ｎｍ未満の触媒金属微粒子を、このＳｉ基板の面に形成させる工程と、この工程で得られたＳｉ基板が配置されたチャンバーの内部に炭素含有ガスを供給するとともにプラズマ電子を発生させる工程と、を有するＣＮＴの生成方法であっても、先端に磁気特性を持つ鉄系金属微粒子を包含したＣＮＴがウィスカー状に生成され、ＣＮＴと鉄系金属の磁気特性が得られる新しいナノ材料の誕生が期待できるのである。 In addition, after depositing iron-based metal having magnetic properties or catalytic metal fine particles of less than 100 nm containing ions of the iron-based metal on the surface of the Si substrate, CNTs are generated on the surface of the Si substrate by plasma CVD. In some cases, it is not always necessary to prevent plasma electrons generated from the microwave generator 6 from directly irradiating the surface of the Si substrate. For example, when there is another method capable of generating highly oriented CNTs on the surface of the Si substrate, catalyst metal fine particles having magnetic properties are also included at the tips of the CNTs generated by the other methods, We can expect the birth of new nanomaterials. That is, a method of generating CNTs on a Si substrate by the plasma DVD method, and forming iron-based metal having magnetic properties or catalytic metal fine particles of less than 100 nm containing ions of this iron-based metal on the surface of the Si substrate. And a method of producing CNTs having a step of supplying a carbon-containing gas into a chamber in which the Si substrate obtained in this step is disposed and generating plasma electrons, It is expected that CNTs containing iron-based metal fine particles having a whisker will be produced in the form of whiskers and that new nanomaterials that can obtain the magnetic properties of CNT and iron-based metals can be expected.
次に、ＣＮＴ生成工程における遮蔽部材７の効果を、実験により確認している。実験方法及び実験結果について、以下に説明する。なお、本実験では、基板１０としてＳｉ（１００）を、触媒金属としてＦｅを、炭素含有ガスとしてメタン（ＣＨ4）を、触媒金属微粒子付着処理工程として自己成長法を用いた。 Next, the effect of the shielding member 7 in the CNT generation process is confirmed by experiments. The experimental method and experimental results will be described below. In this experiment, Si (100) was used as the substrate 10, Fe was used as the catalyst metal, methane (CH 4 ) was used as the carbon-containing gas, and a self-growth method was used as the catalyst metal fine particle adhesion treatment step.
先ず、触媒金属微粒子付着処理工程について説明する。Ｓｉ基板１０は、長時間大気に暴露されていると、表面に吸着物や不純物ならびに酸化層が存在していると考えられるので、触媒金属微粒子を基板１０に付着させるための予備処理として、基板１０の洗浄処理を行った。以下に、基板１０の洗浄方法について説明する。 First, the catalyst metal fine particle adhesion treatment process will be described. When the Si substrate 10 is exposed to the atmosphere for a long time, it is considered that adsorbates, impurities, and oxide layers are present on the surface. Therefore, as a pretreatment for attaching the catalytic metal fine particles to the substrate 10, Ten washing treatments were performed. Below, the washing | cleaning method of the board | substrate 10 is demonstrated.
（基板洗浄処理）
基板１０の洗浄は、半導体業界では標準的な科学的洗浄法であるＲＣＡ法と呼ばれる方法を用いて行った。その手順は以下のとおりである。
（１）試料を１００％エタノールで５分間、純水で５分間超音波洗浄する。
（２）（１）と平行して濃度２８％のＮＨ4ＯＨと濃度３０％のＨ2Ｏ2の比率が１：１の混合液を沸騰させておく。
（３）（１）で洗浄した基板１０を濃度２％のＨＦ溶液に数秒浸して、基板１０の表面をエッチングする。
（４）過剰のＨＦを取り除くために純水に約５秒浸す。
（５）基板１０を上記（２）で用意した混合液に約１０分間浸す。これはＨ2Ｏ2の強い酸化作用とＮＨ4ＯＨ水の溶解作用により有機汚染物を除去することが目的である。また、Ａｕ，Ａｇ，Ｃｕ，Ｎｉ，Ｃｄ，Ｚｎ，Ｃｏ，ＣｒなどのIbIIb族やその他の金属不純物がＮＨ4ＯＨとの化合物生成反応により除去される。例えば、ＣｕはＣｕ（ＮＨ3）4 2+を形成する。
（６）混合液から基板１０を取り出し、冷却、洗浄するために純水に約１分間浸す。
（７）冷却された基板１０を濃度２％のＨＦ溶液に数秒浸して表面を水素終端する。
（８）過剰のＨＦを取り除くために純水に約５秒浸す。
（９）上記（５）〜（８）のプロセスを更に２回繰り返す。
（１０）３回目の行程では、ＨＦ溶液で表面を水素終端した後、純水に約１分間浸す。
（１１）純水から基板１０を取り出して自然乾燥させる。
(Substrate cleaning process)
The substrate 10 was cleaned using a method called an RCA method which is a standard scientific cleaning method in the semiconductor industry. The procedure is as follows.
(1) The sample is ultrasonically washed with 100% ethanol for 5 minutes and with pure water for 5 minutes.
(2) In parallel with (1), a mixed solution having a ratio of 28% NH 4 OH to 30% H 2 O 2 of 1: 1 is boiled.
(3) The surface of the substrate 10 is etched by immersing the substrate 10 cleaned in (1) in an HF solution having a concentration of 2% for several seconds.
(4) Soak in pure water for about 5 seconds to remove excess HF.
(5) The substrate 10 is immersed in the mixed solution prepared in (2) for about 10 minutes. The purpose of this is to remove organic contaminants by the strong oxidizing action of H 2 O 2 and the dissolving action of NH 4 OH water. Moreover, Au, Ag, Cu, Ni , Cd, Zn, Co, it b II b group and other metal impurities such as Cr is removed by compound formation reaction with NH 4 OH. For example, Cu forms Cu (NH 3 ) 4 2+ .
(6) The substrate 10 is taken out from the mixed solution and immersed in pure water for about 1 minute for cooling and cleaning.
(7) The cooled substrate 10 is immersed in a 2% concentration HF solution for several seconds to terminate the surface with hydrogen.
(8) Soak in pure water for about 5 seconds to remove excess HF.
(9) The processes (5) to (8) are repeated twice more.
(10) In the third step, the surface is hydrogen-terminated with an HF solution, and then immersed in pure water for about 1 minute.
(11) The substrate 10 is taken out from the pure water and naturally dried.
なお、本実験においてはＲＣＡ洗浄を用いて基板１０の洗浄を行ったが、これに限られるものではなく、基板１０の表面に存在している吸着物や不純物の除去ができれば、いかなる洗浄法であってもよい。 In this experiment, the substrate 10 was cleaned using RCA cleaning. However, the present invention is not limited to this, and any cleaning method can be used as long as the adsorbate and impurities present on the surface of the substrate 10 can be removed. There may be.
（触媒金属微粒子付着処理工程）
基板１０の洗浄を終えたのちは、触媒金属の自己成長法により１００ｎｍ未満の触媒金属微粒子を基板１０の表面に付着させる処理を行った。本実験においては、Ｓｉ基板１０の面にＳｉＯ2薄膜をパターニング形成させたのちに触媒金属であるＦｅを真空蒸着させた。このように、ＳｉＯ2薄膜をパターニング形成させたのは、ＳｉＯ2薄膜が形成された部分の面に触媒金属の微粒子が自己成長して整列することを利用し、任意のパターンにＣＮＴを生成させるためである。
(Catalyst metal fine particle adhesion treatment process)
After finishing the cleaning of the substrate 10, a process of attaching catalyst metal fine particles of less than 100 nm to the surface of the substrate 10 was performed by a catalytic metal self-growth method. In this experiment, after forming a SiO 2 thin film on the surface of the Si substrate 10, Fe as a catalytic metal was vacuum deposited. In this way, the SiO 2 thin film is formed by patterning, and the catalytic metal fine particles are self-grown and aligned on the surface of the portion where the SiO 2 thin film is formed, thereby generating CNTs in an arbitrary pattern. Because.
このように、表面にＦｅが真空蒸着されたＳｉ基板１０を、図１に図示されるマイクロ波プラズマＣＶＤ装置１の基板保持部５に保持してチャンバー２の加熱処理を行った。具体的には、基板１０の温度が７００℃となるように加熱装置４でチャンバー２内の加熱を行い、炭素含有ガス供給部３からＨ2の供給を行った。そして、ロータリーポンプ８でチャンバー２内を真空度が４．０×１０-4Ｐａ以下になるまで減圧することで、チャンバー２内を１００％Ｈ2雰囲気とした。この状態で、３０分間基板１０の加熱処理を行った。 Thus, the Si substrate 10 having Fe vacuum-deposited on the surface was held on the substrate holding portion 5 of the microwave plasma CVD apparatus 1 shown in FIG. Specifically, the inside of the chamber 2 was heated by the heating device 4 so that the temperature of the substrate 10 became 700 ° C., and H 2 was supplied from the carbon-containing gas supply unit 3. Then, the inside of the chamber 2 was reduced in pressure by the rotary pump 8 until the degree of vacuum became 4.0 × 10 −4 Pa or less, thereby making the inside of the chamber 2 a 100% H 2 atmosphere. In this state, the substrate 10 was heat-treated for 30 minutes.
（ＣＮＴ生成工程）
基板１０の加熱処理後、基板１０の温度を７００℃に保ったまま、炭素含有ガス供給部３からチャンバー２内にメタン（ＣＨ4）を供給し、基板１０に−５００Ｖのバイアス電圧を印加しながらマイクロ波プラズマＣＶＤを行った。
(CNT production process)
After the heat treatment of the substrate 10, while maintaining the temperature of the substrate 10 at 700 ° C., methane (CH 4 ) is supplied from the carbon-containing gas supply unit 3 into the chamber 2, and a bias voltage of −500 V is applied to the substrate 10. However, microwave plasma CVD was performed.
本実験では、基板保持部５（即ち、基板１０）とマイクロ波発生部６の間に遮蔽部材７が設けられていない領域（以下、「プラズマ暴露領域」という。）と、遮蔽部材７が設けられた領域（以下、「非プラズマ暴露領域」という。）と、これらの境界領域の各領域におけるＣＮＴの成長度合いを観察した。なお、かかる観察は、基板１０の表面を走査型電子顕微鏡（以下、「ＳＥＭ」という。）で観察することによって行った。 In this experiment, a region where the shielding member 7 is not provided between the substrate holding unit 5 (that is, the substrate 10) and the microwave generation unit 6 (hereinafter referred to as “plasma exposure region”) and the shielding member 7 are provided. The degree of CNT growth was observed in each of these regions (hereinafter referred to as “non-plasma exposure regions”) and the boundary regions. This observation was performed by observing the surface of the substrate 10 with a scanning electron microscope (hereinafter referred to as “SEM”).
ここで、図３は、各領域を示す概念図であって、図３に図示されるＡがプラズマ暴露領域、Ｂが境界領域、及びＣが非プラズマ暴露領域である。図３に図示されていないが、マイクロ波発生部６は、基板１０との間に遮蔽部材７が配置されるように、紙面の前方向からみて遮蔽部材７の上方に位置している。また、図４は、基板１０の表面をＳＥＭで観察した写真であって、（ａ）がプラズマ暴露領域、（ｂ）が境界領域、（ｃ）が非プラズマ暴露領域における写真である。なお、かかるＳＥＭ観察では、ＣＮＴの長さ方向への成長を観察し易い様、基板１０を３０度傾けて観察を行っている。また、図５は、反応時間とＣＮＴの長さ方向への成長の関係を示した図であって、（ａ）が非プラズマ暴露領域、（ｂ）がプラズマ暴露領域における図である。なお、反応時間を１０秒〜６０秒の範囲で変化させて実験を行い、縦軸にＣＮＴの長さ（μｍ）、横軸に反応時間（秒）を示している。また、今回の実験では、反応時間以外の生成条件は変化させていない。 Here, FIG. 3 is a conceptual diagram showing each region, in which A shown in FIG. 3 is a plasma exposure region, B is a boundary region, and C is a non-plasma exposure region. Although not illustrated in FIG. 3, the microwave generation unit 6 is located above the shielding member 7 when viewed from the front of the page so that the shielding member 7 is disposed between the microwave generation unit 6 and the substrate 10. FIG. 4 is a photograph of the surface of the substrate 10 observed with an SEM, where (a) is a plasma exposure region, (b) is a boundary region, and (c) is a non-plasma exposure region. In this SEM observation, the substrate 10 is tilted by 30 degrees for easy observation of the growth of CNTs in the length direction. FIG. 5 is a diagram showing the relationship between the reaction time and the growth of CNT in the length direction, where (a) is a non-plasma exposure region and (b) is a plasma exposure region. The experiment was conducted while changing the reaction time in the range of 10 to 60 seconds. The vertical axis represents the CNT length (μm), and the horizontal axis represents the reaction time (seconds). In this experiment, the production conditions other than the reaction time were not changed.
図４によれば、（ａ）のプラズマ暴露領域、及び（ｂ）の境界領域では、程度は異なるものの、いずれの領域においてもＣＮＴの先端構造が破壊され、炭素堆積膜が生成されていることが確認できる。一方、（ｃ）の非プラズマ暴露領域では、長さ約１０μｍの一様な高配向ＣＮＴ薄膜の生成が確認できる。 According to FIG. 4, the CNT tip structure is destroyed and a carbon deposition film is generated in each region, although the extent is different in the plasma exposure region (a) and the boundary region (b). Can be confirmed. On the other hand, in the non-plasma exposed region of (c), the formation of a uniform highly oriented CNT thin film having a length of about 10 μm can be confirmed.
また、図５によれば、（ａ）の非プラズマ暴露領域では、反応時間６０秒でＣＮＴの長さが１２μｍ（成長速度２００ｎｍ／ｓ）に達している。一方、（ｂ）のプラズマ暴露領域では、反応時間６０秒でＣＮＴの長さが約１．５μｍと、（ａ）の非プラズマ暴露領域と比べてＣＮＴの成長が抑制されている。 Further, according to FIG. 5, in the non-plasma exposure region of (a), the length of CNT reaches 12 μm (growth rate 200 nm / s) after a reaction time of 60 seconds. On the other hand, in the plasma exposure region of (b), the CNT length is about 1.5 μm at a reaction time of 60 seconds, and the growth of CNT is suppressed as compared with the non-plasma exposure region of (a).
このように、非プラズマ暴露領域におけるＣＮＴの成長速度（２００ｎｍ／ｓ）は、プラズマ暴露領域におけるＣＮＲの成長速度と比べて非常に速いことから、基板１０をプラズマ暴露させることは、ＣＮＴの成長に悪影響を及ぼしていることが分かる。 Thus, the growth rate of CNT (200 nm / s) in the non-plasma exposure region is very high compared to the growth rate of CNR in the plasma exposure region. Therefore, exposing the substrate 10 to plasma increases the growth of CNTs. It turns out that it has an adverse effect.
したがって、基板保持部５とマイクロ波発生部６との間に遮蔽部材７を設け、基板１０に直射しない様にチャンバー２内にプラズマ電子を発生させることで、高配向ＣＮＴ薄膜を基板１０の表面に生成させることが確認できた。 Therefore, the shielding member 7 is provided between the substrate holding unit 5 and the microwave generation unit 6, and plasma electrons are generated in the chamber 2 so as not to directly irradiate the substrate 10. It was confirmed that it was generated.
尚、本発明は、上記の好ましい実施形態に記載されているが、本発明はそれだけに制限されない。本発明の精神と範囲から逸脱することのない様々な実施形態が他になされることができることは理解されよう。 In addition, although this invention is described in said preferable embodiment, this invention is not restrict | limited only to it. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention.
１ マイクロ波プラズマＣＶＤ装置、
２ チャンバー
３ 炭素含有ガス供給部
４ 加熱装置
５ 基板保持部
６ マイクロ波発生部
７ 遮蔽部材
８ ロータリーポンプ
９ マグネトロン
１０ 基板
Ａ プラズマ暴露領域
Ｂ 境界領域
Ｃ 非プラズマ暴露領域
1 microwave plasma CVD equipment,
2 Chamber 3 Carbon-containing gas supply unit 4 Heating device 5 Substrate holding unit 6 Microwave generation unit 7 Shielding member 8 Rotary pump 9 Magnetron 10 Substrate A Plasma exposure region B Boundary region C Non-plasma exposure region
Claims (6)
Ｆｅ，Ｃｏ，Ｎｉ，Ｇａ，Ｉｎ（ＩＴＯ），Ａｌ，Ｓｎの少なくともいずれかの金属を含む触媒を前記基板の面に付着させる第１の工程と、
前記第１の工程で得られた基板が配置されたチャンバーの内部に、炭素含有ガスを供給するとともにプラズマ電子を発生させる第２の工程と、を有し、
前記第２の工程が、前記チャンバーの内部に発生させるプラズマ電子が前記基板に直射しないように遮蔽する工程を有することを特徴とするカーボンナノチューブの生成方法。 A carbon nanotube production method for producing carbon nanotubes on a substrate by a plasma CVD method,
A first step of attaching a catalyst containing at least one of Fe, Co, Ni, Ga, In (ITO), Al, and Sn to the surface of the substrate;
A second step of supplying a carbon-containing gas and generating plasma electrons inside the chamber in which the substrate obtained in the first step is disposed;
The method for producing carbon nanotubes, wherein the second step includes a step of shielding plasma electrons generated in the chamber from direct irradiation to the substrate.
前記チャンバーの内部に配置され、前記基板を保持可能な基板保持部と、
前記チャンバー内にプラズマ電子を発生させるマイクロ波発生部と、
前記基板保持部と前記マイクロ波発生部との間に、前記マイクロ波発生部から発生するプラズマ電子の前記基板への直射を遮る遮蔽部材と、を備えることを特徴とするカーボンナノチューブの生成装置。 A carbon nanotube generating apparatus that supplies a carbon-containing gas into a chamber in which a substrate is disposed, and generates carbon nanotubes on the surface of the substrate by a plasma CVD method,
A substrate holding part disposed inside the chamber and capable of holding the substrate;
A microwave generator for generating plasma electrons in the chamber;
A carbon nanotube generating apparatus comprising: a shielding member that blocks direct irradiation of plasma electrons generated from the microwave generating unit onto the substrate between the substrate holding unit and the microwave generating unit.
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