WO2014192955A1 - Method for generating graphene and method for growing carbon nanotube - Google Patents

Method for generating graphene and method for growing carbon nanotube Download PDF

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Publication number
WO2014192955A1
WO2014192955A1 PCT/JP2014/064562 JP2014064562W WO2014192955A1 WO 2014192955 A1 WO2014192955 A1 WO 2014192955A1 JP 2014064562 W JP2014064562 W JP 2014064562W WO 2014192955 A1 WO2014192955 A1 WO 2014192955A1
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Prior art keywords
metal layer
laser beam
carbon
catalyst metal
irradiation
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PCT/JP2014/064562
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French (fr)
Japanese (ja)
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貴士 松本
友策 井澤
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東京エレクトロン株式会社
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Priority claimed from JP2013112927A external-priority patent/JP2014231454A/en
Priority claimed from JP2013119802A external-priority patent/JP2014237557A/en
Application filed by 東京エレクトロン株式会社 filed Critical 東京エレクトロン株式会社
Publication of WO2014192955A1 publication Critical patent/WO2014192955A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/186—Preparation by chemical vapour deposition [CVD]
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00—Structure or properties of graphene
    • C01B2204/04—Specific amount of layers or specific thickness

Definitions

  • the present invention relates to a method for producing graphene and a method for growing carbon nanotubes, and more particularly to a method for producing graphene and a method for growing carbon nanotubes that can be suitably used for semiconductor devices in which wirings and the like are miniaturized.
  • a metal such as Cu is used for wiring of a three-dimensional stacked memory.
  • a metal wiring material such as Cu
  • conduction electrons are inelastically scattered at the interface due to a thin wire effect. Because of the strong influence, there is a problem that the resistance of the wiring is increased.
  • graphene has an extremely long mean free path and high mobility, and when applied to a fine wiring structure, the possibility of realizing a low resistance wiring exceeding Cu has been shown (for example, non (See Patent Document 1). Therefore, in the next-generation three-dimensional stacked memory that needs to realize a finer stacked structure and wiring structure, it has been studied to use graphene as a wiring film instead of Cu.
  • a CVD method for example, thermal CVD method or plasma CVD method
  • the substrate surface is covered with a catalytic metal layer
  • the catalytic metal layer is activated, and then decomposed from the source gas.
  • the carbon atoms are dissolved in the activated catalytic metal layer and recrystallized. That is, since graphene can be directly generated on a substrate having a relatively large area, the CVD method can be easily adapted to an existing semiconductor device formation process.
  • a plasma CVD method is mainly used in which the substrate gas needs to be heated only to a relatively low temperature, for example, 600 ° C. or less by decomposing the source gas with plasma.
  • a hydrocarbon-based gas is used as a source gas, plasma is generated from the hydrocarbon-based gas, and carbon radicals in the plasma are dissolved in the catalyst metal layer (see, for example, Patent Document 1). .
  • the thickness of the graphene is adjusted, that is, the carbon of the generated graphene It is important to reliably control the number of atomic layers.
  • Carbon nanotubes are mainly used as wiring materials in semiconductor devices because of their excellent electrical conductivity (low electrical resistance), thermal conductivity (high heat dissipation), and current density resistance (high electromigration resistance). It is expected as a next-generation wiring material to replace Cu. In particular, since the above-described features become apparent when the carbon nanotubes are densified, it is strongly required to arrange the carbon nanotubes at a high density.
  • CVD method As a method for growing carbon nanotubes, arc discharge method, laser ablation method, liquid phase method, chemical vapor deposition method and the like are known, but CVD method is preferable from the viewpoint of productivity, controllability, and semiconductor process consistency. Used for.
  • CVD method a catalytic CVD method is generally used in which catalytic metal fine particles such as Fe, Co, and Ni are formed on a substrate, and carbon nanotubes are grown using the catalytic metal fine particles as nuclei.
  • the catalytic metal fine particles are formed by sputtering, a method of directly depositing fine particles on the substrate such as an arc plasma gun, or a method of obtaining catalytic metal fine particles by performing plasma treatment on the catalytic metal layer.
  • a method of directly depositing fine particles on the substrate such as an arc plasma gun
  • a method of obtaining catalytic metal fine particles by performing plasma treatment on the catalytic metal layer For example, refer to Patent Document 2. Since carbon nanotubes grow according to the size of the catalyst metal fine particles, to obtain carbon nanotubes arranged at high density, for example, fine catalyst metal fine particles, for example, catalyst metal fine particles with a size (diameter) of nano-order size are formed. There is a need to. Graphene and carbon nanotubes are collectively referred to as nanocarbon.
  • a substrate is placed on a stage and the substrate is heated by a ceramic heater or the like built in the stage, but the heating by the ceramic heater is indirect to the substrate. Because of heating, it is difficult to maintain the temperature of the substrate, that is, the catalyst metal layer at a desired temperature, and it is difficult to dissolve a desired amount of carbon atoms in the catalyst metal layer.
  • the catalyst metal layer of the substrate is cooled by stopping energization to the ceramic heater and dissipating heat from the ceramic heater.
  • the ceramic heater since the ceramic heater has low heat dissipation, the temperature does not drop rapidly, and the catalyst metal layer It takes time to cool the metal, and there is a possibility that a desired amount or more of carbon atoms may be dissolved in the catalyst metal layer. As a result, the amount of carbon crystals that precipitate when the catalytic metal layer is cooled is unnecessarily reduced or increased, so that it is difficult to reliably control the number of carbon atom layers of the generated graphene. .
  • the thermal energy imparted by the plasma is too small, the aggregation of the catalytic metal atoms is difficult to progress, so that fine catalytic metal fine particles are not formed. If the thermal energy imparted by the plasma is excessive, the aggregation is excessive. The catalyst metal fine particles larger than necessary are formed as a result. As a result, there is a problem that it is not easy to obtain high-density carbon nanotubes.
  • the first object of the present invention is to provide a graphene production method capable of reliably controlling the number of carbon atom layers of graphene produced.
  • a second object of the present invention is to provide a carbon nanotube growth method capable of obtaining high-density carbon nanotubes.
  • a method for producing graphene comprising: a heating step of heating the catalytic metal layer with the irradiated laser beam; and a cooling step of stopping irradiation of the laser beam on the catalytic metal layer.
  • the carbon-containing gas is preferably decomposed by the laser beam.
  • the catalytic metal layer is preferably scanned with the laser beam.
  • the laser beam is irradiated to a predetermined portion of the catalyst metal layer without scanning the catalyst metal layer with the laser beam.
  • the surface of the substrate is preferably scanned with the laser beam.
  • the carbon-containing layer is preferably formed on the catalyst metal layer.
  • the catalytic metal layer is preferably formed on the carbon-containing layer.
  • a catalyst metal fine particle forming step for forming catalyst metal fine particles from a catalyst metal layer
  • the catalyst metal fine particle formation step includes applying a laser to the catalyst metal layer.
  • a carbon nanotube growth method having a carbon nanotube growth step of growing from metal fine particles.
  • the laser beam irradiation step it is preferable to scan the catalytic metal layer with the laser beam.
  • the catalyst metal fine particles are irradiated with the laser light through a space in which the carbon-containing gas is supplied.
  • the carbon nanotube growth step it is preferable to scan the surface of the substrate on which the catalytic metal fine particles are formed by the laser beam.
  • nanocarbon such as graphene and high-density carbon nanotubes in which the number of carbon atom layers is controlled by controlling the thermal energy applied during the formation of nanocarbon.
  • FIG. 1 is a cross-sectional view schematically showing a configuration of a laser beam heating apparatus used in the graphene generation method according to the present embodiment.
  • a laser beam heating apparatus 10 is a substantially cylindrical chamber 11 that is hermetically configured, and a semiconductor wafer (hereinafter simply referred to as “wafer”) W that is provided in the chamber 11 and is a substrate to be processed.
  • Wafer semiconductor wafer
  • a laser beam irradiation unit 13 that irradiates infrared laser light toward the surface of the mounted wafer W
  • a gas supply unit 14 that ejects gas into the chamber 11, and the chamber 11.
  • the exhaust part 15 which exhausts the inside of this, and the control part 16 which controls each component of the laser beam heating apparatus 10 are provided.
  • a circular opening 17 is formed in a substantially central portion of the bottom wall 11a of the chamber 11, and the bottom wall 11a communicates with the inside of the chamber 11 through the opening 17 and protrudes downward in the figure.
  • a chamber 18 is provided on the side wall 11 b of the chamber 11, a loading / unloading port 19 for loading / unloading the wafer W into / from the chamber 11 and a gate valve 20 for opening / closing the loading / unloading port 19 are provided.
  • the mounting table 12 is made of, for example, AlN ceramics and is supported by a cylindrical ceramic column 21 that extends upward from the center of the bottom of the exhaust chamber 18. Elevating pins (not shown) for elevating and lowering the wafer W are stored in the mounting table 12, and the elevating pins protrude from the surface of the mounting table 12 to separate the wafer W from the mounting table 12.
  • the laser beam irradiation unit 13 is opposed to the laser beam transmission window 51 fitted in the ceiling wall 11 c of the chamber 11 and the surface of the wafer W mounted on the mounting table 12 through the laser beam transmission window 51.
  • a laser light source 52 disposed outside the chamber 11 and a laser light scanning unit 53 disposed between the laser light source 52 and the laser light transmitting window 51 are configured.
  • the laser beam scanning unit 43 changes the irradiation angle of the infrared laser beam L applied to the wafer W from the laser light source 52 through the laser beam transmission window 51, and scans the surface of the wafer W with the infrared laser beam L.
  • the laser beam irradiation unit 13 can irradiate infrared laser light L having a wavelength of 700 to 11000 nm, for example, and can control the irradiation time of the infrared laser light L in units of milliseconds (msec). For example, as shown in FIG. 3, the laser beam irradiation unit 13 irradiates the wafer W with the infrared laser beam L for several milliseconds, and then immediately stops the irradiation with the infrared laser beam L, thereby instantaneously heat-treating the wafer W. (Spike annealing) can be performed.
  • the gas supply unit 14 includes a gas nozzle 54 disposed on the ceiling wall 11 c of the chamber 11 and a gas supply source 24 disposed outside the chamber 11.
  • the gas supply source 24 is connected to a gas nozzle 54 provided in the chamber 11 via a gas supply pipe 26, and also includes a hydrogen-containing gas supply source 24a that supplies a hydrogen-containing gas, and a carbon-containing gas that supplies a carbon-containing gas. It has the supply source 24b and the inert gas supply source 24c which supplies an inert gas.
  • the gas supply pipe 26 branches into three branch paths 26a, 26b, and 26c, the branch path 26a is connected to the hydrogen-containing gas supply source 24a, the branch path 26b is connected to the carbon-containing gas supply source 24b, and the branch path 26c. Are connected to an inert gas supply 24c.
  • the branch paths 26a, 26b, and 26c are provided with a mass flow controller and a valve (not shown).
  • the gas nozzle 54 introduces a mixed gas of hydrogen-containing gas, carbon-containing gas, and inert gas supplied from the gas supply source 24 through the gas supply pipe 26 into the chamber 11.
  • each gas of H 2 and NH 3 is used as the hydrogen-containing gas, and as the carbon-containing gas, a hydrocarbon gas such as ethylene (C 2 H 4 ), methane (CH 4 ), Ethane (C 2 H 6 ), propane (C 3 H 8 ), propylene (C 3 H 6 ), acetylene (C 2 H 2 ), alcohols such as methanol (CH 3 OH) and ethanol (C 2 H 5) OH), ethanol, or aromatic hydrocarbon gas is used, and as the inert gas, for example, Ar gas, He gas, or N 2 gas is used.
  • the inert gas supplied from the inert gas supply source 24 c is used as, for example, a purge gas or a pressure adjusting gas in the chamber 11.
  • the exhaust unit 15 includes an exhaust chamber 18, an exhaust pipe 29 that opens on a side surface of the exhaust chamber 18, and an exhaust device 30 connected to the exhaust pipe 29.
  • the exhaust device 30 includes a high-speed vacuum pump such as a turbo molecular pump.
  • the exhaust unit 15 causes the gas inside the chamber 11 to flow uniformly into the internal space of the exhaust chamber 18 by operating the exhaust device 30, and further exhausts the gas from the internal space to the outside via the exhaust pipe 29. . Thereby, the inside of the chamber 11 can be rapidly decompressed to, for example, 0.133 Pa.
  • the control unit 16 is a module controller that controls the operation of each component of the laser beam heating apparatus 10.
  • the control unit 16 is typically a computer, and includes, for example, a controller 31 having a CPU, a user interface 32 connected to the controller 31, and a storage unit 33, as shown in FIG.
  • the controller 31 includes components (for example, a laser beam irradiation unit 13 and a gas supply unit 14) related to various processing conditions such as temperature, pressure, gas flow rate, infrared laser beam output and irradiation time. , Exhaust device 30 etc.).
  • the user interface 32 includes a keyboard and a touch panel on which an operator inputs commands for operating the laser light heating device 10, a display that visualizes and displays the operating status of the laser light heating device 10, and the like.
  • the storage unit 33 stores a control program (software) for realizing various processes executed in the laser beam heating apparatus 10 through the control of the controller 31, recipes in which process condition data, and the like are recorded.
  • the control unit 16 calls an arbitrary recipe from the storage unit 33 in response to an instruction from the user interface 32 and causes the controller 31 to execute the recipe. At this time, a desired process, for example, a process corresponding to a graphene generation method of FIG. 4 to be described later is executed in the chamber 11 of the laser beam heating apparatus 10.
  • the recipe in which the control program, processing condition data, and the like are recorded may be stored in a computer-readable recording medium 34.
  • a computer-readable recording medium 34 for example, a CD-ROM, a hard disk, a flexible disk, or a flash memory can be used.
  • a recipe that has been transmitted from another device via a dedicated line or the like may be used.
  • the catalytic metal layer formed on the surface of the wafer W is irradiated with infrared laser light to melt the surface of the catalytic metal layer, and carbon atoms are dissolved in the catalytic metal layer. Thereafter, the catalyst metal layer is cooled to precipitate carbon crystals to generate graphene.
  • FIG. 4 is a process diagram showing a method for producing graphene according to the present embodiment.
  • a wafer W is prepared in which a silicon oxide (eg, SiO 2 ) layer 36, a nitride film (eg, TiN) layer 37, and a catalytic metal layer 38 are laminated in this order on a silicon base 35 ( 4A), the gate valve 20 of the laser beam heating apparatus 10 is opened, and the wafer W is loaded into the chamber 11 from the loading / unloading port 19 and mounted on the mounting table 12.
  • a metal constituting the catalytic metal layer 38 of the wafer W transition metals such as Cu, Fe, Co, Ni, Ru, Au, or alloys containing these transition metals are applicable.
  • the catalytic metal layer 38 is formed by a known film formation technique such as sputtering, vapor deposition, CVD, or plating.
  • the wafer W may be a glass substrate, a plastic (polymer) substrate, or the like instead of the silicon substrate.
  • the gas nozzle 54 of the gas supply unit 14 supplies a mixed gas of carbon-containing gas, hydrogen-containing gas, and inert gas toward the catalyst metal layer 38, and the laser beam irradiation unit 13 continues to supply the mixed gas.
  • Infrared laser light L is irradiated toward the catalytic metal layer 38 of the wafer W ((B) of FIG. 4).
  • the carbon-containing gas in the mixed gas is preferably CH 4 gas, C 2 H 4 gas, C 2 H 2 gas or the like, and the hydrogen-containing gas in the mixed gas is preferably H 2 gas or NH 3 gas, and mixed As the inert gas in the gas, Ar gas, He gas or N 2 gas is preferable.
  • the supply of the mixed gas and the irradiation with the infrared laser beam L may be started simultaneously.
  • a portion irradiated with the infrared laser light L in the catalytic metal layer 38 is referred to as an irradiation portion.
  • the hydrogen-containing gas in the mixed gas supplied toward the catalyst metal layer 38 reduces the oxide thin film (for example, a natural oxide film) on the surface of the catalyst metal layer 38 by heating by irradiation with the infrared laser beam L, thereby reducing the catalyst metal.
  • the surface of the layer 38 at the irradiated position is activated.
  • the carbon-containing gas in the mixed gas is decomposed into carbon atoms and other atoms by heating by irradiation with the infrared laser beam L.
  • the temperature of the catalytic metal layer 38 is increased by heating by irradiation with the infrared laser beam L, the catalytic metal layer 38 is melted, and the solubility of the catalytic metal layer 38 is also improved. Atoms are dissolved in the catalytic metal layer 38.
  • the temperature of the catalyst metal layer 38 can be easily maintained at a desired temperature. Therefore, in the graphene generation method of FIG. 4, a desired amount of carbon atoms is dissolved in the catalytic metal layer 38 using the characteristics of the infrared laser beam L described above.
  • the irradiation site is irradiated for several milliseconds, for example, 0.001 to 1000 msec, and the temperature of the irradiation site is preferably 300 to 900 ° C., preferably 100 to 10,000 W.
  • the irradiation with the infrared laser beam L is preferably stopped before the solid solution of carbon atoms in the catalytic metal layer 38 is saturated.
  • the inside of the chamber 11 is heated by a heater (not shown), and the temperature of the irradiated portion is, for example, room temperature to 600 ° C., preferably 300 ° C. to 400 ° C. May be raised.
  • the irradiation of the infrared laser beam L is stopped.
  • the catalyst metal layer 38 is cooled, but the supply of heat to the catalyst metal layer 38 can be stopped immediately by stopping the irradiation of the infrared laser light L, and the catalyst metal layer 38 is rapidly cooled to It is possible to prevent a desired amount or more of carbon atoms from dissolving in the metal layer 38.
  • the cooling time of the catalytic metal layer 38 by stopping the irradiation with the infrared laser beam L is within 5 seconds, preferably within 3 seconds.
  • the number of carbon atom layers 40 of graphene 39 is also a number corresponding to a desired amount. That is, in the graphene generation method of FIG. 4, a desired amount of carbon atoms can be accurately dissolved in the catalyst metal layer 38, and as a result, the amount of carbon crystals precipitated from the catalyst metal layer 38 is accurately controlled. Therefore, the number of carbon atom layers 40 of the generated graphene 39 can be reliably controlled.
  • the irradiation spot in the catalyst metal layer 38 corresponds to the spot of the infrared laser beam L
  • the spot of the infrared laser beam L in the catalyst metal layer 38 is obtained.
  • Graphene 39 is generated in the corresponding area.
  • the infrared laser light L is parallel to the surface of the wafer W by the spot diameter of the infrared laser light L ((( B) in the direction of the black arrow in FIG. 4 and the execution of the graphene generation method of FIG. 4 is repeated. That is, since the catalyst metal layer 38 is scanned by the infrared laser beam L, a desired amount of carbon atoms can be accurately dissolved in the catalyst metal layer 38 in a wide range of the catalyst metal layer 38, and thus, over a wide range. When the graphene 39 is generated, the number of the carbon atom layers 40 can be reliably controlled.
  • the pressure inside the chamber 11 is preferably 13 to 1333 Pa, and more preferably 66 to 666 Pa, from the viewpoint of increasing the partial pressure of the carbon-containing gas to promote solid solution of carbon atoms.
  • the flow rate of the carbon-containing gas in the mixed gas is preferably set to, for example, 1 to 100 mL / min (sccm) from the viewpoint of supplying a large amount of carbon atoms and quickly dissolving the carbon atoms in the catalytic metal layer 38. 5 to 50 mL / min (sccm) is more preferable.
  • This embodiment is basically the same in configuration and operation as the first embodiment described above, and the first embodiment described above in that a carbon-containing layer is formed instead of supplying a carbon-containing gas. Different from form. Therefore, the description of the duplicated configuration and operation is omitted, and the description of the different configuration and operation is given below.
  • FIG. 5 is a process diagram showing a graphene generation method according to the present embodiment.
  • a wafer W having a film configuration similar to that of the wafer in the first embodiment is prepared (FIG. 5A), and the carbon whose thickness is controlled to a predetermined value on the catalyst metal layer 38 is prepared.
  • the containing layer 41 is formed ((B) of FIG. 5).
  • the carbon-containing layer 41 is formed by a known film forming technique such as a vapor deposition method, a CVD method, a screen method, or coating.
  • the gate valve 20 of the laser beam heating device 10 is opened, the wafer W is loaded into the chamber 11 from the loading / unloading port 19 and placed on the mounting table 12, and the laser beam irradiation unit 13 is a catalyst for the wafer W.
  • the infrared laser beam L is irradiated toward the metal layer 38 and the carbon-containing layer 41, and the gas nozzle 54 of the gas supply unit 14 supplies an inert gas toward the catalyst metal layer 38.
  • a carbon solid solution layer 42 is formed by solid solution in the catalyst metal layer 38 ((C) of FIG. 5).
  • the carbon atoms dissolved in the catalyst metal layer 38 are supplied from the carbon-containing layer 41. Since the thickness of the carbon-containing layer 41 is controlled to a predetermined value, the carbon atoms dissolved in the catalyst metal layer 38 are controlled. The amount corresponds to a predetermined thickness, and a desired amount or more of carbon atoms does not dissolve in the catalyst metal layer 38.
  • the temperature of the catalytic metal layer 38 is maintained at a desired temperature by adjusting the output of the infrared laser beam L and the irradiation time, and a desired amount of carbon atoms is dissolved in the catalytic metal layer 38 in a desired amount.
  • irradiation of the irradiated portion of the infrared laser beam L with an output of 100 to 10000 W is continued for several milliseconds, for example, 0.001 to 1000 msec, so that the temperature of the irradiated portion is 300 to 900 ° C., preferably Raises the temperature to 400 to 600 ° C.
  • the entire surface of the catalytic metal layer 38 is scanned with the infrared laser light L, and the infrared laser light L is irradiated for several milliseconds at each irradiation location. .
  • a desired amount of carbon atoms can be accurately dissolved in the catalytic metal layer 38 in a wide range of the catalytic metal layer 38.
  • the carbon-containing layer 41 is formed on the catalyst metal layer 38 in the wafer W, but the catalyst is formed on the carbon-containing layer 41 by forming the carbon-containing layer 41 before the catalyst metal layer 38.
  • a metal layer 38 may be formed.
  • the carbon-containing layer 41 is melted by the infrared laser beam L, but the carbon-containing layer 41 may be melted by plasma.
  • This embodiment is basically the same in configuration and operation as the first embodiment described above, and is different from the first embodiment described above in that the catalytic metal layer 38 is not scanned by the infrared laser light L. Different. Therefore, the description of the duplicated configuration and operation is omitted, and the description of the different configuration and operation is given below.
  • FIG. 6 is a process diagram showing a graphene generation method according to the present embodiment.
  • FIG. 6 a wafer W having a film configuration similar to that of the wafer in the first embodiment is prepared (FIG. 6A), the gate valve 20 of the laser beam heating device 10 is opened, and the carry-in / out port 19 is opened. Then, the wafer W is loaded into the chamber 11 and placed on the mounting table 12.
  • the infrared laser beam L is irradiated from the laser beam irradiation unit 13 toward only a predetermined portion of the catalyst metal layer 38 of the wafer W without scanning the entire area of the catalyst metal layer 38 with the infrared laser beam L.
  • migration due to heating occurs at a predetermined location, aggregation of metal atoms constituting the catalytic metal layer 38 occurs, and a protruding step 43 is generated ((B) of FIG. 6).
  • the protrusion amount of step 43 changes according to the irradiation time of the infrared laser beam L
  • the irradiation time of the infrared laser beam L is adjusted to adjust the protrusion amount of step 43 to a desired value.
  • the gas nozzle 54 of the gas supply unit 14 supplies a mixed gas of carbon-containing gas, hydrogen-containing gas, and inert gas toward the catalyst metal layer 38.
  • the hydrogen-containing gas in the supplied mixed gas is activated by reducing the surface of step 43 by heating by irradiation with infrared laser light L.
  • the carbon-containing gas in the mixed gas is decomposed into carbon atoms and other atoms by heating by irradiation with the infrared laser beam L.
  • the infrared laser light L may be continuously irradiated through the formation of Step 43 and the supply of the mixed gas. After Step 43 is formed, the irradiation of the infrared laser light L is temporarily stopped and the mixed gas is supplied. After the supply is started, the infrared laser beam L may be irradiated again.
  • the irradiation time of the infrared laser light L is adjusted to fix the carbon atoms in the catalyst metal layer 38 by a desired amount. Dissolve. Specifically, the irradiation of step 43 with infrared laser light L having an output of 100 to 10000 W is continued for several milliseconds, for example, 0.001 to 1000 msec, whereby the temperature of step 43 is preferably 300 to 900 ° C., preferably Raises the temperature to 400 to 600 ° C. and causes step 43 to dissolve the carbon atom in a desired amount. The irradiation with the infrared laser beam L is preferably stopped before the solid solution of carbon atoms in step 43 is saturated.
  • the irradiation of the infrared laser beam L is stopped.
  • the supply of heat to the step 43 can be stopped immediately, so that the step 43 is rapidly cooled so that a desired amount or more of carbon atoms dissolve in the step 43. Can be prevented.
  • the carbon atoms dissolved in step 43 are saturated, carbon crystals are precipitated from the surface of step 43, and graphene 39 grows from step 43.
  • the amount of precipitated carbon crystals corresponds to the desired amount, and thus grows graphene 39.
  • the number of the carbon atom layers 40 can be reliably controlled.
  • the number of the carbon atom layers 40 of the graphene 39 can be reliably increased by adjusting the irradiation time of the infrared laser light L and adjusting the protrusion amount in step 43 to a desired value. Can be controlled.
  • the temperature of the catalytic metal layer 38 other than step 43 does not rise. There is no solid solution in the layer 38. Thereby, it is possible to prevent the graphene 39 from growing from other than step 43. Therefore, by selecting the location where the step 43 is generated, the location where the graphene 39 grows can be adjusted.
  • the pressure inside the chamber 11 is preferably 13 to 1333 Pa and more preferably 66 to 666 Pa from the viewpoint of increasing the partial pressure of the carbon-containing gas and promoting solid solution of carbon atoms.
  • the flow rate of the carbon-containing gas in the mixed gas is preferably set to, for example, 1 to 100 mL / min (sccm) from the viewpoint of supplying a large amount of carbon atoms and promptly dissolving the carbon atoms in step 43. ⁇ 50 mL / min (sccm) is more preferred.
  • the catalytic metal layer 38 covers the entire surface of the wafer W, but the catalytic metal layer 38 may be formed only at the location where the step 43 is generated. Further, when the carbon crystal is precipitated from the surface of Step 43, the irradiation of the infrared laser light L is stopped and the step 43 is rapidly cooled. However, the supply of the mixed gas is continued without stopping the irradiation of the infrared laser light L. In step 43, carbon atoms that are solid solution may be saturated to precipitate carbon crystals.
  • fine metal particles are formed by irradiating the catalytic metal layer formed on the surface of the wafer W with infrared laser light, and the carbon-containing gas is decomposed into carbon atoms by the infrared laser light.
  • Carbon nanotubes are grown by recrystallizing carbon atoms using fine particles as nuclei.
  • FIG. 7 is a process diagram showing a carbon nanotube growth method according to the present embodiment.
  • FIG. 7 first, a wafer W having the same film configuration as that of the wafer in the first embodiment is prepared (FIG. 7A).
  • the laser beam irradiation unit 13 irradiates the infrared laser beam L toward the catalytic metal layer 38 of the wafer W.
  • the infrared laser beam L imparts thermal energy to the catalytic metal layer 38, migration occurs on the surface of the catalytic metal layer 38 to which thermal energy has been imparted, and aggregation of catalytic metal atoms in the catalytic metal layer 38 occurs, resulting in catalytic metal. Fine particles 44 are formed (FIG. 7B).
  • the amount of thermal energy applied to the irradiated portion in the catalytic metal layer 38 can be accurately controlled. Therefore, in the carbon nanotube growth method of FIG. 7, the amount of thermal energy applied to the catalytic metal layer 38 is adjusted using the characteristics of the infrared laser light L described above.
  • the irradiation site is irradiated for several milliseconds, for example, 0.001 to 1000 msec, and the temperature of the irradiation site is preferably 300 to 900 ° C., preferably 100 to 10,000 W.
  • the gas supply unit 14 ejects the mixed gas into the chamber 11.
  • the mixed gas is supplied from the gas supply source 24, but the mixed gas may contain only an inert gas, for example, N 2 gas, He gas, or Ar gas.
  • a hydrogen-containing gas for example, H 2 gas and NH 3 gas may contain.
  • hydrogen atoms generated from the hydrogen-containing gas by heating with the infrared laser beam L reduce the surface of the catalyst metal fine particles 44 and activate the catalyst metal fine particles 44.
  • the pressure inside the chamber 11 is preferably 13 to 1333 Pa, and more preferably 66 to 666 Pa, from the viewpoint of suppressing evaporation of the molten catalyst metal layer 38.
  • the flow rate of the hydrogen-containing gas in the mixed gas is, for example, 1 to 100 mL / min (sccm) from the viewpoint of reliably activating the catalytic metal fine particles 44 formed by supplying a large amount of hydrogen atoms. 5 to 50 mL / min (sccm) is more preferable.
  • the amount of applied thermal energy increases, migration is promoted, and the aggregation of catalytic metal atoms proceeds excessively.
  • the size of the catalyst metal fine particles 44 may exceed a desired value.
  • the irradiation of the infrared laser light L onto the catalytic metal layer 38 is stopped.
  • the application of thermal energy to the catalytic metal layer 38 can be stopped immediately, and the aggregation of the catalytic metal atoms can be stopped immediately.
  • the growth of the catalyst metal fine particles 44 can be immediately stopped to prevent the size of the catalyst metal fine particles 44 from exceeding a desired value.
  • the determination as to whether or not the size of the catalyst metal fine particles 44 has reached the desired value is based on whether or not the time until the size of the catalyst metal fine particles 44 reaches the desired value is measured in advance.
  • the determination method is not limited to this.
  • the determination may be performed by directly confirming the size of the catalytic metal fine particles 44 with an SEM.
  • the size of the catalytic metal fine particles 44 is preferably about 1 to 50 nm, for example.
  • the amount of atoms of the catalyst metal to be aggregated is reduced, and the diameter of the formed catalyst metal fine particles 44 is also reduced.
  • the diameter of the formed catalytic metal fine particles 44 is about 10 nm
  • the diameter of the formed catalytic metal fine particles 44 Is about 20 nm.
  • the catalytic metal layer 38 corresponds to the spot of the infrared laser beam L, when the irradiation of the infrared laser beam L and the stop of the irradiation are performed, the catalytic metal layer 38 corresponds to the spot of the infrared laser beam L.
  • the catalytic metal fine particles 44 are generated by the area to be used.
  • the infrared laser light L is parallel to the surface of the wafer W by the spot diameter of the infrared laser light L (FIG. 7).
  • the irradiation of the infrared laser beam L and the stop of the irradiation are repeated. That is, since the catalyst metal layer 38 is scanned by the infrared laser beam L, the catalyst metal fine particles 44 can be generated in a wide range of the catalyst metal layer 38.
  • the amount of thermal energy applied to each irradiation site is made uniform, so that the degree of aggregation of catalytic metal atoms at each irradiation site is made the same.
  • the catalyst metal fine particles 44 having a uniform size can be generated in a wide range of the catalyst metal layer 38.
  • the laser beam irradiation unit 13 irradiates the infrared laser beam L again toward each irradiation location, and the gas supply unit 14 ejects a mixed gas into the chamber 11 and then toward the catalytic metal fine particles 44.
  • the infrared laser light L is irradiated to each irradiation place through a processing space inside the chamber 11 to which the mixed gas is supplied.
  • the mixed gas includes a carbon-containing gas such as C 2 H 4 gas and an inert gas such as Ar gas.
  • the inert gas acts as a carrier gas.
  • the C 2 H 4 gas in the mixed gas is thermally decomposed into carbon atoms by the infrared laser beam L irradiated toward each irradiation location.
  • carbon atoms generated by thermal decomposition are used to recrystallize carbon atoms with each catalytic metal fine particle 44 as a nucleus to form carbon nanotubes 45 ((C) in FIG. 7).
  • the amount of thermal energy applied to the irradiated portion is adjusted. Specifically, by irradiating the infrared laser beam L with an output of 100 to 10000 W, the temperature of the irradiated portion is raised to 300 to 900 ° C., preferably 400 to 600 ° C. By maintaining the irradiation on the irradiated portion for several minutes, for example, 1 to 60 minutes, the thermal decomposition of the C 2 H 4 gas into carbon atoms is continued, and the supply of carbon atoms is continued. Continue to grow.
  • the inside of the chamber 11 may be heated with a heater, and the temperature of the irradiated portion may be raised to, for example, room temperature to 600 ° C., preferably 300 ° C. to 400 ° C.
  • the temperature rise width of the irradiated part by the irradiation with the infrared laser beam L it is possible to reduce the temperature rise width of the irradiated part by the irradiation with the infrared laser beam L, so that the controllability of the temperature rise by the irradiation with the infrared laser beam L can be improved, and the temperature rise control at the irradiation part It can be done precisely.
  • the formation of the carbon nanotubes 40 is stopped by stopping the irradiation of the infrared laser light L and quenching the catalytic metal fine particles 44.
  • the cooling time of the catalytic metal fine particles 44 due to the stop of the irradiation of the infrared laser light L is as follows. Within 5 seconds, preferably within 3 seconds.
  • the pressure inside the chamber 11 is preferably 13 to 1333 Pa (0.1 to 10 Torr), and more preferably 66 Pa to 667 Pa, from the viewpoint of maintaining a sufficient growth rate of the carbon nanotubes.
  • the flow rate of the C 2 H 4 gas in the mixed gas is preferably 1 to 100 mL / min (sccm), for example, and 5 to 50 mL / min (sccm). More preferred.
  • the carbon-containing gas in the mixed gas is not limited to C 2 H 4 gas, but may be hydrocarbon gas such as CH 4 , C 2 H 6 , C 3 H 8 , C 3 H 6 , C 2 H 2 , Carbon-containing gases such as CH 3 OH, C 2 H 5 OH can be used instead.
  • Ar gas instead of Ar gas, other rare gases, for example, He, Ne, Kr, Xe gases or N 2 gas may be used.
  • Ar gas other rare gases, for example, He, Ne, Kr, Xe gases or N 2 gas may be used.
  • N 2 gas may be used as an inert gas.
  • the use of an inert gas is not essential.
  • the flow rate is preferably 100 to 2000 mL / min (sccm), for example, from the viewpoint of efficiently growing the carbon nanotubes 45, and is preferably 300 to 1000 mL / min ( sccm) is more preferred.
  • the flow rate is preferably 100 to 1000 mL / min (sccm), for example, from the viewpoint of efficiently growing the carbon nanotube 45, and is preferably 100 to 300 mL / min (sccm). Is more preferable.
  • the mixed gas may contain a hydrogen-containing gas such as H 2 gas or NH 3 gas in addition to the carbon-containing gas or the inert gas.
  • a hydrogen-containing gas such as H 2 gas or NH 3 gas
  • hydrogen atoms generated from the hydrogen-containing gas by heating with the infrared laser beam L reduce the surface of the catalyst metal fine particles 44 and activate the catalyst metal fine particles 44. Thereby, the growth of the carbon nanotube 45 having the catalyst metal fine particles 44 as a nucleus can be promoted.
  • the mixed gas for example, O 2, O 3, H 2 O
  • the mixed gas may be added to oxidizing gases such as N 2 O.
  • the quality of the carbon nanotube 45 can be improved.
  • the carbon nanotube 45 grows while maintaining the properties of the catalytic metal fine particles 44, the catalytic metal fine particles having a fine and uniform size in a wide range by using the above-described irradiation of the infrared laser beam L and the repetition of the stop of the irradiation.
  • High density carbon nanotubes 45 can be obtained by generating 44 and realizing the distribution of the high density catalyst metal fine particles 44 on the wafer W.
  • the laser beam is grown.
  • the irradiation unit 13 and the gas supply unit 14 are moved in parallel with the surface of the wafer W by the spot diameter of the infrared laser light L (in the direction of the black arrow in FIG. 7C), so that the carbon nanotubes 45 are moved at other irradiation points. Grow.
  • the fine carbon nanotubes 45 can be grown over a wide range of the surface of the wafer W.
  • the amount of heat energy applied to each irradiation point is made uniform, thereby making the amount of carbon atoms supplied at each irradiation point the same.
  • the carbon nanotubes 45 having a uniform length can be grown in a wide range of the catalytic metal layer 38.
  • the catalytic metal layer 38 is irradiated with the infrared laser light L to heat the catalytic metal layer 38.
  • the infrared laser light L accurately adjusts the output and irradiation time. Therefore, the amount of thermal energy applied to the catalyst metal layer 38 can be accurately controlled, and the degree of aggregation of the catalyst metal atoms can be accurately controlled. Further, the irradiation of the infrared laser light L to the catalytic metal layer 38 is stopped and the catalytic metal layer 38 is cooled, but the application of thermal energy to the catalytic metal layer 38 is immediately stopped by the stop of the irradiation of the infrared laser light L.
  • the catalytic metal can be solidified while maintaining the agglomeration that has progressed to an appropriate degree.
  • fine catalyst metal fine particles 44 can be formed from the catalyst metal layer 38, and thus high-density carbon nanotubes 45 can be obtained.
  • both the formation of the catalyst metal fine particles 44 and the growth of the carbon nanotubes 45 can be performed by irradiation with the infrared laser light L. Therefore, the formation of the catalyst metal fine particles 44 and the carbon nanotube 45 Thus, the same laser beam heating apparatus 10 can be used to improve the throughput and the equipment cost.
  • the growth of the carbon nanotube 45 may be performed using a plasma processing apparatus that generates carbon atoms by decomposing the carbon-containing gas with plasma.
  • the carbon nanotube 45 is not damaged due to electrons and ions in the plasma, and the introduction of crystal defects and impurities is suppressed.
  • the carbon nanotube 45 with few impurities can be formed.

Abstract

Provided is a method for generating a graphene, whereby the number of carbon atom layers of a generated graphene can be reliably controlled. A laser-beam heating device (10), wherein an infrared laser beam (L) is emitted from a laser beam emission unit (13) to a catalyst metal layer (38) of a wafer (W) mounted on a mounting stage (12), and a gas mixture including a carbon-containing gas is supplied to the catalyst metal layer (38) from a gas supply unit (14), after which emission of the infrared laser beam (L) to the catalyst metal layer (38) is stopped and the catalyst metal layer (38) is rapidly cooled.

Description

グラフェンの生成方法及びカーボンナノチューブの成長方法Graphene production method and carbon nanotube growth method
　本発明は、グラフェンの生成方法及びカーボンナノチューブの成長方法、特に、配線等が微細化された半導体デバイスへ好適に用いることができるグラフェンの生成方法及びカーボンナノチューブの成長方法に関する。 The present invention relates to a method for producing graphene and a method for growing carbon nanotubes, and more particularly to a method for producing graphene and a method for growing carbon nanotubes that can be suitably used for semiconductor devices in which wirings and the like are miniaturized.
　従来、三次元積層メモリの配線には金属、例えば、Ｃｕが用いられているが、Ｃｕ等の金属配線材料によって形成された極微細配線構造では、細線効果によって伝導電子が界面における非弾性散乱の影響を強く受けるため、配線が高抵抗化するという問題がある。 Conventionally, a metal such as Cu is used for wiring of a three-dimensional stacked memory. However, in an extremely fine wiring structure formed of a metal wiring material such as Cu, conduction electrons are inelastically scattered at the interface due to a thin wire effect. Because of the strong influence, there is a problem that the resistance of the wiring is increased.
　これに対し、グラフェンは極めて長い平均自由行程や高移動度を有しており、微細配線構造に適用した場合、Ｃｕを超える低抵抗の配線の実現の可能性も示されている（例えば、非特許文献１参照。）。したがって、より微細な積層構造や配線構造を実現する必要がある次世代の三次元積層メモリでは、Ｃｕの代わりにグラフェンを配線膜に用いることが検討されている。 On the other hand, graphene has an extremely long mean free path and high mobility, and when applied to a fine wiring structure, the possibility of realizing a low resistance wiring exceeding Cu has been shown (for example, non (See Patent Document 1). Therefore, in the next-generation three-dimensional stacked memory that needs to realize a finer stacked structure and wiring structure, it has been studied to use graphene as a wiring film instead of Cu.
　グラフェンの生成方法として代表的な方法であるＣＶＤ法（例えば、熱ＣＶＤ法やプラズマＣＶＤ法）では、基板表面を触媒金属層で覆い、該触媒金属層を活性化した後、原料ガスから分解された炭素原子を一度活性化された触媒金属層へ溶かし込み、該炭素原子を再結晶させる。すなわち、比較的大面積の基板上において直接グラフェンを生成することができるため、ＣＶＤ法は既存の半導体デバイス形成プロセスへ容易に適合させることができる。 In a CVD method (for example, thermal CVD method or plasma CVD method), which is a representative method for generating graphene, the substrate surface is covered with a catalytic metal layer, the catalytic metal layer is activated, and then decomposed from the source gas. The carbon atoms are dissolved in the activated catalytic metal layer and recrystallized. That is, since graphene can be directly generated on a substrate having a relatively large area, the CVD method can be easily adapted to an existing semiconductor device formation process.
　ＣＶＤ法のうち、熱ＣＶＤ法では原料ガスを熱分解するために基板を約１０００℃まで加熱する必要があり、三次元積層メモリにおける他の配線や絶縁膜が変質するおそれがあるため、現状では、原料ガスをプラズマで分解することにより、基板を比較的低温、例えば、６００℃以下までしか加熱する必要がないプラズマＣＶＤ法が主に用いられている。プラズマＣＶＤ法では原料ガスとして、例えば、炭化水素系ガスを用い、該炭化水素系ガスからプラズマを生成し、プラズマ中の炭素ラジカルを触媒金属層へ固溶させる（例えば、特許文献１参照。）。 Among the CVD methods, in the thermal CVD method, it is necessary to heat the substrate to about 1000 ° C. in order to thermally decompose the source gas, and there is a possibility that other wirings and insulating films in the three-dimensional stacked memory may be altered. A plasma CVD method is mainly used in which the substrate gas needs to be heated only to a relatively low temperature, for example, 600 ° C. or less by decomposing the source gas with plasma. In the plasma CVD method, for example, a hydrocarbon-based gas is used as a source gas, plasma is generated from the hydrocarbon-based gas, and carbon radicals in the plasma are dissolved in the catalyst metal layer (see, for example, Patent Document 1). .
　特に、次世代の三次元積層メモリではより微細な積層構造や配線構造を実現する必要があることから、グラフェンを配線に用いる場合、当該グラフェンの厚さの調整、すなわち、生成されるグラフェンの炭素原子層の層数を確実に制御することが重要である。 In particular, since the next generation three-dimensional stacked memory needs to realize a finer stacked structure and wiring structure, when graphene is used for wiring, the thickness of the graphene is adjusted, that is, the carbon of the generated graphene It is important to reliably control the number of atomic layers.
　また、カーボンナノチューブは優れた電気伝導性（低電気抵抗）、熱伝導性（高放熱性）、電流密度耐性（高エレクトロマイグレーション耐性）を有するという特徴から、半導体デバイスにおいて配線材料として主に用いられるＣｕに代わる次世代の配線材料として期待されている。特に上述した特徴はカーボンナノチューブを高密度化すれば顕在化するため、カーボンナノチューブを高密度に配置することが強く求められている。 Carbon nanotubes are mainly used as wiring materials in semiconductor devices because of their excellent electrical conductivity (low electrical resistance), thermal conductivity (high heat dissipation), and current density resistance (high electromigration resistance). It is expected as a next-generation wiring material to replace Cu. In particular, since the above-described features become apparent when the carbon nanotubes are densified, it is strongly required to arrange the carbon nanotubes at a high density.
　カーボンナノチューブの成長方法としては、アーク放電法、レーザーアブレーション法、液相法、化学気相堆積法等が知られているが、生産性、制御性、半導体プロセス整合性の観点からＣＶＤ法が好適に用いられる。ＣＶＤ法としては、基板上にＦｅ、Ｃｏ、Ｎｉ等の触媒金属微粒子を形成し、該触媒金属微粒子を核としてカーボンナノチューブを成長させる触媒ＣＶＤ法が一般的に用いられる。 As a method for growing carbon nanotubes, arc discharge method, laser ablation method, liquid phase method, chemical vapor deposition method and the like are known, but CVD method is preferable from the viewpoint of productivity, controllability, and semiconductor process consistency. Used for. As the CVD method, a catalytic CVD method is generally used in which catalytic metal fine particles such as Fe, Co, and Ni are formed on a substrate, and carbon nanotubes are grown using the catalytic metal fine particles as nuclei.
　触媒ＣＶＤ法では、触媒金属微粒子の形成に、スパッタ法、アークプラズマガンのように微粒子を直接基板上に堆積させる方法、若しくは、触媒金属層にプラズマ処理を施して触媒金属微粒子を得る方法が用いられる（例えば、特許文献２参照。）。カーボンナノチューブは触媒金属微粒子の大きさに従って成長するため、高密度に配置されたカーボンナノチューブを得るには、微細な触媒金属微粒子、例えば、大きさ（直径）がナノオーダーサイズの触媒金属微粒子を形成する必要がある。なお、グラフェン及びカーボンナノチューブはナノカーボンと総称される。 In the catalytic CVD method, the catalytic metal fine particles are formed by sputtering, a method of directly depositing fine particles on the substrate such as an arc plasma gun, or a method of obtaining catalytic metal fine particles by performing plasma treatment on the catalytic metal layer. (For example, refer to Patent Document 2). Since carbon nanotubes grow according to the size of the catalyst metal fine particles, to obtain carbon nanotubes arranged at high density, for example, fine catalyst metal fine particles, for example, catalyst metal fine particles with a size (diameter) of nano-order size are formed. There is a need to. Graphene and carbon nanotubes are collectively referred to as nanocarbon.
特開２０１０−２１２６１９号公報JP 2010-212619 A 特開２０１０−１６３３３１号公報JP 2010-163331 A
　ところで、熱ＣＶＤ法を用いてグラフェンを生成する場合、基板をステージに載置し、該ステージが内蔵するセラミックヒータ等によって当該基板を加熱するが、セラミックヒータによる加熱は基板に対して間接的な加熱となるため、基板、引いては触媒金属層の温度を所望の温度に維持するのが困難であり、触媒金属層へ所望量の炭素原子を固溶させるのが困難である。また、セラミックヒータへの通電を停止してセラミックヒータの放熱を中断させることによって基板の触媒金属層を冷却するが、セラミックヒータは放熱性が低いために急速に温度が低下せず、触媒金属層の冷却にも時間を要し、触媒金属層へ所望量以上の炭素原子が固溶するおそれもある。その結果、触媒金属層を冷却した際に析出する炭素結晶の量が必要以上に減少し、若しくは増加するため、生成されるグラフェンの炭素原子層の層数を確実に制御することは困難である。 By the way, when generating graphene using a thermal CVD method, a substrate is placed on a stage and the substrate is heated by a ceramic heater or the like built in the stage, but the heating by the ceramic heater is indirect to the substrate. Because of heating, it is difficult to maintain the temperature of the substrate, that is, the catalyst metal layer at a desired temperature, and it is difficult to dissolve a desired amount of carbon atoms in the catalyst metal layer. In addition, the catalyst metal layer of the substrate is cooled by stopping energization to the ceramic heater and dissipating heat from the ceramic heater. However, since the ceramic heater has low heat dissipation, the temperature does not drop rapidly, and the catalyst metal layer It takes time to cool the metal, and there is a possibility that a desired amount or more of carbon atoms may be dissolved in the catalyst metal layer. As a result, the amount of carbon crystals that precipitate when the catalytic metal layer is cooled is unnecessarily reduced or increased, so that it is difficult to reliably control the number of carbon atom layers of the generated graphene. .
　プラズマＣＶＤ法を用いてグラフェンを生成する場合、基板の触媒金属層がプラズマに晒されて当該プラズマから熱を受けるが、プラズマの密度分布の精密な制御は困難であるため、触媒金属層がプラズマから受ける熱量を制御するのは困難であり、引いては触媒金属層の温度を所望の温度に維持するのが困難である。また、プラズマの消滅には時間を要するため、触媒金属層の冷却にも時間を要するおそれもある。その結果、熱ＣＶＤ法を用いてグラフェンを生成する場合と同様に、触媒金属層を冷却した際に析出する炭素結晶の量が必要以上に減少し、若しくは増加するため、生成されるグラフェンの炭素原子層の層数を確実に制御することは困難である。 When graphene is generated using the plasma CVD method, the catalytic metal layer of the substrate is exposed to the plasma and receives heat from the plasma, but it is difficult to precisely control the density distribution of the plasma. It is difficult to control the amount of heat received from the catalyst, and it is difficult to maintain the temperature of the catalyst metal layer at a desired temperature. Further, since it takes time to extinguish the plasma, it may take time to cool the catalytic metal layer. As a result, as in the case of generating graphene using a thermal CVD method, the amount of carbon crystals that precipitate when the catalytic metal layer is cooled is unnecessarily reduced or increased. It is difficult to reliably control the number of atomic layers.
　また、触媒金属層にプラズマ処理を施して触媒金属微粒子を得る場合、触媒金属層へプラズマによって熱エネルギーを付与し、該熱エネルギーに起因するマイグレーションによって触媒金属の原子を凝集させる。 When the catalyst metal layer is subjected to plasma treatment to obtain catalyst metal fine particles, thermal energy is applied to the catalyst metal layer by plasma, and the atoms of the catalyst metal are aggregated by migration caused by the heat energy.
　しかしながら、プラズマの密度の制御は容易ではないため、プラズマが触媒金属層へ付与する熱エネルギーの量を正確に制御するのは困難であり、微細な触媒金属微粒子を形成するのは困難である。 However, since it is not easy to control the density of the plasma, it is difficult to accurately control the amount of thermal energy that the plasma imparts to the catalytic metal layer, and it is difficult to form fine catalytic metal fine particles.
　例えば、プラズマが付与する熱エネルギーが少なすぎると、触媒金属の原子の凝集が進展しにくいために微細な触媒金属微粒子が形成されず、プラズマが付与する熱エネルギーが多すぎると、凝集が過度に進行して必要以上の大きさの触媒金属微粒子が形成される。その結果、高密度のカーボンナノチューブを得るのは容易でないという問題がある。 For example, if the thermal energy imparted by the plasma is too small, the aggregation of the catalytic metal atoms is difficult to progress, so that fine catalytic metal fine particles are not formed. If the thermal energy imparted by the plasma is excessive, the aggregation is excessive. The catalyst metal fine particles larger than necessary are formed as a result. As a result, there is a problem that it is not easy to obtain high-density carbon nanotubes.
　本発明の第１の目的は、生成されるグラフェンの炭素原子層の層数を確実に制御することができるグラフェンの生成方法を提供することにある。 The first object of the present invention is to provide a graphene production method capable of reliably controlling the number of carbon atom layers of graphene produced.
　本発明の第２の目的は、高密度のカーボンナノチューブを得ることができるカーボンナノチューブの成長方法を提供することにある。 A second object of the present invention is to provide a carbon nanotube growth method capable of obtaining high-density carbon nanotubes.
　上記第１の目的を達成するために、本発明によれば、触媒金属層へ向けて少なくとも炭素含有ガスを供給するガス供給ステップと、前記触媒金属層へレーザ光を照射するレーザ光照射ステップと、前記照射されたレーザ光によって前記触媒金属層を加熱する加熱ステップと、前記触媒金属層への前記レーザ光の照射を停止する冷却ステップとを有するグラフェンの生成方法が提供される。 In order to achieve the first object, according to the present invention, a gas supply step of supplying at least a carbon-containing gas toward the catalytic metal layer, and a laser light irradiation step of irradiating the catalytic metal layer with laser light; There is provided a method for producing graphene, comprising: a heating step of heating the catalytic metal layer with the irradiated laser beam; and a cooling step of stopping irradiation of the laser beam on the catalytic metal layer.
　本発明において、前記レーザ光によって前記炭素含有ガスを分解することが好ましい。 In the present invention, the carbon-containing gas is preferably decomposed by the laser beam.
　本発明において、前記加熱ステップでは、前記レーザ光によって前記触媒金属層を走査することが好ましい。 In the present invention, in the heating step, the catalytic metal layer is preferably scanned with the laser beam.
　本発明において、前記加熱ステップでは、前記レーザ光によって前記触媒金属層を走査することなく、前記触媒金属層の所定の箇所へ前記レーザ光を照射することが好ましい。 In the present invention, in the heating step, it is preferable that the laser beam is irradiated to a predetermined portion of the catalyst metal layer without scanning the catalyst metal layer with the laser beam.
　本発明において、前記ガス供給ステップ及び前記レーザ光照射ステップを同時に行うことが好ましい。 In the present invention, it is preferable to perform the gas supply step and the laser beam irradiation step simultaneously.
　上記第１の目的を達成するために、本発明によれば、触媒金属層及び厚さが制御された炭素含有層が表面に形成された基板へレーザ光を照射する加熱ステップと、前記触媒金属層への前記レーザ光の照射を停止する冷却ステップとを有するグラフェンの生成方法が提供される。 In order to achieve the first object, according to the present invention, a heating step of irradiating a laser beam onto a substrate on which a catalytic metal layer and a carbon-containing layer with a controlled thickness are formed, and the catalytic metal And a cooling step of stopping irradiation of the laser beam on the layer.
　本発明において、前記加熱ステップでは、前記レーザ光によって前記基板の表面を走査することが好ましい。 In the present invention, in the heating step, the surface of the substrate is preferably scanned with the laser beam.
　本発明において、前記触媒金属層の上に前記炭素含有層が形成されていることが好ましい。 In the present invention, the carbon-containing layer is preferably formed on the catalyst metal layer.
　本発明において、前記炭素含有層の上に前記触媒金属層が形成されていることが好ましい。 In the present invention, the catalytic metal layer is preferably formed on the carbon-containing layer.
　上記第２の目的を達成するために、本発明によれば、触媒金属層から触媒金属微粒子を形成する触媒金属微粒子形成ステップを有し、前記触媒金属微粒子形成ステップは、前記触媒金属層へレーザ光を照射するレーザ光照射ステップと、前記触媒金属層への前記レーザ光の照射を停止するレーザ光照射停止ステップと、前記触媒金属微粒子へ向けて炭素含有ガスを供給してカーボンナノチューブを前記触媒金属微粒子から成長させるカーボンナノチューブ成長ステップとを有するカーボンナノチューブの成長方法が提供される。 In order to achieve the second object, according to the present invention, there is provided a catalyst metal fine particle forming step for forming catalyst metal fine particles from a catalyst metal layer, and the catalyst metal fine particle formation step includes applying a laser to the catalyst metal layer. A laser beam irradiation step of irradiating light, a laser beam irradiation stop step of stopping irradiation of the laser beam on the catalyst metal layer, and a carbon-containing gas supplied to the catalyst metal fine particles to convert the carbon nanotube into the catalyst There is provided a carbon nanotube growth method having a carbon nanotube growth step of growing from metal fine particles.
　本発明において、前記レーザ光照射ステップでは、前記レーザ光によって前記触媒金属層を走査することが好ましい。 In the present invention, in the laser beam irradiation step, it is preferable to scan the catalytic metal layer with the laser beam.
　本発明において、前記カーボンナノチューブ成長ステップにおいて、前記炭素含有ガスが供給されている空間を介して前記触媒金属微粒子へ前記レーザ光を照射することが好ましい。 In the present invention, it is preferable that, in the carbon nanotube growth step, the catalyst metal fine particles are irradiated with the laser light through a space in which the carbon-containing gas is supplied.
　本発明において、前記カーボンナノチューブ成長ステップでは、前記レーザ光によって前記触媒金属微粒子が形成された基板の表面を走査することが好ましい。 In the present invention, in the carbon nanotube growth step, it is preferable to scan the surface of the substrate on which the catalytic metal fine particles are formed by the laser beam.
　本発明によれば、ナノカーボンの形成時に与える熱エネルギーを制御することにより、炭素原子層の層数が制御されたグラフェンや高密度のカーボンナノチューブ等の高品質なナノカーボンを得ることができる。 According to the present invention, it is possible to obtain high-quality nanocarbon such as graphene and high-density carbon nanotubes in which the number of carbon atom layers is controlled by controlling the thermal energy applied during the formation of nanocarbon.
本発明の第１の実施の形態に係るグラフェンの生成方法に用いられるレーザ光加熱装置の構成を概略的に示す断面図である。It is sectional drawing which shows roughly the structure of the laser beam heating apparatus used for the production | generation method of the graphene based on the 1st Embodiment of this invention. 図１における制御部の構成を概略的に示すブロック図である。It is a block diagram which shows schematically the structure of the control part in FIG. 図１におけるレーザ光照射部による赤外線レーザ光の照射形態を示すグラフである。It is a graph which shows the irradiation form of the infrared laser beam by the laser beam irradiation part in FIG. 本実施の形態に係るグラフェンの生成方法を示す工程図である。It is process drawing which shows the production | generation method of the graphene which concerns on this Embodiment. 本発明の第２の実施の形態に係るグラフェンの生成方法を示す工程図である。It is process drawing which shows the production | generation method of the graphene which concerns on the 2nd Embodiment of this invention. 本発明の第３の実施の形態に係るグラフェンの生成方法を示す工程図である。It is process drawing which shows the production | generation method of the graphene based on the 3rd Embodiment of this invention. 本発明の第４の実施の形態に係るカーボンナノチューブの成長方法を示す工程図である。It is process drawing which shows the growth method of the carbon nanotube which concerns on the 4th Embodiment of this invention.
　以下、本発明の実施の形態について図面を参照しながら詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
　まず、本発明の第１の実施の形態に係るグラフェンの生成方法について説明する。 First, a method for producing graphene according to the first embodiment of the present invention will be described.
　図１は、本実施の形態に係るグラフェンの生成方法に用いられるレーザ光加熱装置の構成を概略的に示す断面図である。 FIG. 1 is a cross-sectional view schematically showing a configuration of a laser beam heating apparatus used in the graphene generation method according to the present embodiment.
　図１において、レーザ光加熱装置１０は、気密に構成された略円筒状のチャンバ１１と、チャンバ１１の内部に設けられ、被処理基板である半導体ウエハ（以下、単に「ウエハ」という。）Ｗを載置する載置台１２と、載置されたウエハＷの表面へ向けて赤外線レーザ光を照射するレーザ光照射部１３と、チャンバ１１の内部へガスを噴出するガス供給部１４と、チャンバ１１の内部を排気する排気部１５と、レーザ光加熱装置１０の各構成要素を制御する制御部１６とを備える。 In FIG. 1, a laser beam heating apparatus 10 is a substantially cylindrical chamber 11 that is hermetically configured, and a semiconductor wafer (hereinafter simply referred to as “wafer”) W that is provided in the chamber 11 and is a substrate to be processed. , A laser beam irradiation unit 13 that irradiates infrared laser light toward the surface of the mounted wafer W, a gas supply unit 14 that ejects gas into the chamber 11, and the chamber 11. The exhaust part 15 which exhausts the inside of this, and the control part 16 which controls each component of the laser beam heating apparatus 10 are provided.
　チャンバ１１の底壁１１ａの略中央部には円形の開口部１７が形成され、底壁１１ａには開口部１７を介してチャンバ１１の内部と連通し、且つ図中下方に向けて突出する排気室１８が設けられる。チャンバ１１の側壁１１ｂには、チャンバ１１へウエハＷを搬出入するための搬出入口１９と、該搬出入口１９を開閉するゲートバルブ２０とが設けられる。 A circular opening 17 is formed in a substantially central portion of the bottom wall 11a of the chamber 11, and the bottom wall 11a communicates with the inside of the chamber 11 through the opening 17 and protrudes downward in the figure. A chamber 18 is provided. On the side wall 11 b of the chamber 11, a loading / unloading port 19 for loading / unloading the wafer W into / from the chamber 11 and a gate valve 20 for opening / closing the loading / unloading port 19 are provided.
　載置台１２は、例えば、ＡｌＮのセラミックスから構成され、排気室１８の底部中央から上方に延出された円筒状のセラミックス製の支柱２１によって支持される。載置台１２の内部にはウエハＷを昇降するための昇降ピン（図示せず）が格納され、該昇降ピンは載置台１２の表面から突出してウエハＷを載置台１２から離間させる。 The mounting table 12 is made of, for example, AlN ceramics and is supported by a cylindrical ceramic column 21 that extends upward from the center of the bottom of the exhaust chamber 18. Elevating pins (not shown) for elevating and lowering the wafer W are stored in the mounting table 12, and the elevating pins protrude from the surface of the mounting table 12 to separate the wafer W from the mounting table 12.
　レーザ光照射部１３は、チャンバ１１の天井壁１１ｃに嵌め込まれたレーザ光透過窓５１と、該レーザ光透過窓５１を介して載置台１２に載置されたウエハＷの表面へ対向するようにチャンバ１１の外部に配置されるレーザ光源５２と、該レーザ光源５２及びレーザ光透過窓５１の間に配置されるレーザ光走査部５３とによって構成される。レーザ光走査部４３はレーザ光源５２からレーザ光透過窓５１を介してウエハＷへ照射される赤外線レーザ光Ｌの照射角を変更し、赤外線レーザ光ＬによってウエハＷの表面を走査する。 The laser beam irradiation unit 13 is opposed to the laser beam transmission window 51 fitted in the ceiling wall 11 c of the chamber 11 and the surface of the wafer W mounted on the mounting table 12 through the laser beam transmission window 51. A laser light source 52 disposed outside the chamber 11 and a laser light scanning unit 53 disposed between the laser light source 52 and the laser light transmitting window 51 are configured. The laser beam scanning unit 43 changes the irradiation angle of the infrared laser beam L applied to the wafer W from the laser light source 52 through the laser beam transmission window 51, and scans the surface of the wafer W with the infrared laser beam L.
　また、レーザ光照射部１３は、例えば、波長が７００~１１０００ｎｍの赤外線レーザ光Ｌを照射可能であり、赤外線レーザ光Ｌの照射時間をミリ秒（ｍｓｅｃ）単位で制御することができる。例えば、レーザ光照射部１３は、図３に示すように、数ミリ秒だけ赤外線レーザ光Ｌを照射し、その後、直ちに赤外線レーザ光Ｌの照射を停止することにより、ウエハＷへ瞬間的な熱処理（スパイクアニール）を施すことができる。 The laser beam irradiation unit 13 can irradiate infrared laser light L having a wavelength of 700 to 11000 nm, for example, and can control the irradiation time of the infrared laser light L in units of milliseconds (msec). For example, as shown in FIG. 3, the laser beam irradiation unit 13 irradiates the wafer W with the infrared laser beam L for several milliseconds, and then immediately stops the irradiation with the infrared laser beam L, thereby instantaneously heat-treating the wafer W. (Spike annealing) can be performed.
　ガス供給部１４は、チャンバ１１の天井壁１１ｃに配置されるガスノズル５４と、チャンバ１１の外部に配置されるガス供給源２４とを有する。 The gas supply unit 14 includes a gas nozzle 54 disposed on the ceiling wall 11 c of the chamber 11 and a gas supply source 24 disposed outside the chamber 11.
　ガス供給源２４は、ガス供給管２６を介してチャンバ１１に設けられたガスノズル５４へ接続されるとともに、水素含有ガスを供給する水素含有ガス供給源２４ａと、炭素含有ガスを供給する炭素含有ガス供給源２４ｂと、不活性ガスを供給する不活性ガス供給源２４ｃとを有する。ガス供給管２６は３本の分岐路２６ａ、２６ｂ、２６ｃへ分岐し、分岐路２６ａは水素含有ガス供給源２４ａへ接続され、分岐路２６ｂは炭素含有ガス供給源２４ｂへ接続され、分岐路２６ｃは不活性ガス供給源２４ｃへ接続される。分岐路２６ａ、２６ｂ、２６ｃには、図示しないマスフローコントローラやバルブが設けられる。 The gas supply source 24 is connected to a gas nozzle 54 provided in the chamber 11 via a gas supply pipe 26, and also includes a hydrogen-containing gas supply source 24a that supplies a hydrogen-containing gas, and a carbon-containing gas that supplies a carbon-containing gas. It has the supply source 24b and the inert gas supply source 24c which supplies an inert gas. The gas supply pipe 26 branches into three branch paths 26a, 26b, and 26c, the branch path 26a is connected to the hydrogen-containing gas supply source 24a, the branch path 26b is connected to the carbon-containing gas supply source 24b, and the branch path 26c. Are connected to an inert gas supply 24c. The branch paths 26a, 26b, and 26c are provided with a mass flow controller and a valve (not shown).
　ガスノズル５４は、ガス供給管２６を介してガス供給源２４から供給される水素含有ガス、炭素含有ガスや不活性ガスの混合ガスをチャンバ１１の内部に導入する。 The gas nozzle 54 introduces a mixed gas of hydrogen-containing gas, carbon-containing gas, and inert gas supplied from the gas supply source 24 through the gas supply pipe 26 into the chamber 11.
　ガス供給部１４では、水素含有ガスとして、例えば、Ｈ２、ＮＨ３の各ガスが用いられ、炭素含有ガスとして、炭化水素ガス、例えば、エチレン（Ｃ２Ｈ４）、メタン（ＣＨ４）、エタン（Ｃ２Ｈ６）、プロパン（Ｃ３Ｈ８）、プロピレン（Ｃ３Ｈ６）やアセチレン（Ｃ２Ｈ２）、アルコール類、例えば、メタノール（ＣＨ３ＯＨ）やエタノール（Ｃ２Ｈ５ＯＨ）、エタノール類、又は、芳香族炭化水素の各ガスが用いられ、不活性ガスとしては、例えば、Ａｒガス、Ｈｅガス、Ｎ２ガスが用いられる。不活性ガス供給源２４ｃから供給される不活性ガスは、例えば、パージガスやチャンバ１１内の圧力調整用ガスとして用いられる。 In the gas supply unit 14, for example, each gas of H 2 and NH 3 is used as the hydrogen-containing gas, and as the carbon-containing gas, a hydrocarbon gas such as ethylene (C 2 H 4 ), methane (CH 4 ), Ethane (C 2 H 6 ), propane (C 3 H 8 ), propylene (C 3 H 6 ), acetylene (C 2 H 2 ), alcohols such as methanol (CH 3 OH) and ethanol (C 2 H 5) OH), ethanol, or aromatic hydrocarbon gas is used, and as the inert gas, for example, Ar gas, He gas, or N 2 gas is used. The inert gas supplied from the inert gas supply source 24 c is used as, for example, a purge gas or a pressure adjusting gas in the chamber 11.
　排気部１５は、排気室１８と、該排気室１８の側面に開口する排気管２９と、該排気管２９に接続された排気装置３０とを有する。排気装置３０はターボ分子ポンプ等の高速真空ポンプを備えている。排気部１５は、排気装置３０を作動させることにより、チャンバ１１の内部のガスを排気室１８の内部空間へ均一に流し込み、さらに該ガスを当該内部空間から排気管２９を介して外部へ排気する。これにより、チャンバ１１の内部を、例えば、０．１３３Ｐａまで迅速に減圧することができる。 The exhaust unit 15 includes an exhaust chamber 18, an exhaust pipe 29 that opens on a side surface of the exhaust chamber 18, and an exhaust device 30 connected to the exhaust pipe 29. The exhaust device 30 includes a high-speed vacuum pump such as a turbo molecular pump. The exhaust unit 15 causes the gas inside the chamber 11 to flow uniformly into the internal space of the exhaust chamber 18 by operating the exhaust device 30, and further exhausts the gas from the internal space to the outside via the exhaust pipe 29. . Thereby, the inside of the chamber 11 can be rapidly decompressed to, for example, 0.133 Pa.
　制御部１６は、レーザ光加熱装置１０の各構成要素の動作を制御するモジュールコントローラである。制御部１６は、典型的にはコンピュータであり、例えば、図２に示すように、ＣＰＵを備えたコントローラ３１と、該コントローラ３１に接続されたユーザーインターフェース３２と、記憶部３３とを備える。 The control unit 16 is a module controller that controls the operation of each component of the laser beam heating apparatus 10. The control unit 16 is typically a computer, and includes, for example, a controller 31 having a CPU, a user interface 32 connected to the controller 31, and a storage unit 33, as shown in FIG.
　コントローラ３１は、レーザ光加熱装置１０において、温度、圧力、ガス流量、赤外線レーザ光の出力や照射時間等の各種処理条件に関係する各構成要素（例えば、レーザ光照射部１３、ガス供給部１４、排気装置３０等）を制御する。 In the laser beam heating apparatus 10, the controller 31 includes components (for example, a laser beam irradiation unit 13 and a gas supply unit 14) related to various processing conditions such as temperature, pressure, gas flow rate, infrared laser beam output and irradiation time. , Exhaust device 30 etc.).
　ユーザーインターフェース３２は、操作者がレーザ光加熱装置１０を操作するためにコマンドの入力等を行うキーボードやタッチパネル、並びに、レーザ光加熱装置１０の稼働状況を可視化して表示するディスプレイ等を有する。また、記憶部３３は、レーザ光加熱装置１０において実行される各種処理をコントローラ３１の制御を通じて実現するための制御プログラム（ソフトウエア）や処理条件データ等が記録されたレシピ等を保存する。 The user interface 32 includes a keyboard and a touch panel on which an operator inputs commands for operating the laser light heating device 10, a display that visualizes and displays the operating status of the laser light heating device 10, and the like. In addition, the storage unit 33 stores a control program (software) for realizing various processes executed in the laser beam heating apparatus 10 through the control of the controller 31, recipes in which process condition data, and the like are recorded.
　制御部１６は、ユーザーインターフェース３２からの指示等に応じて任意のレシピを記憶部３３から呼び出し、該レシピをコントローラ３１に実行させる。このとき、レーザ光加熱装置１０のチャンバ１１の内部では、所望の処理、例えば、後述する図４のグラフェンの生成方法に対応する処理が実行される。 The control unit 16 calls an arbitrary recipe from the storage unit 33 in response to an instruction from the user interface 32 and causes the controller 31 to execute the recipe. At this time, a desired process, for example, a process corresponding to a graphene generation method of FIG. 4 to be described later is executed in the chamber 11 of the laser beam heating apparatus 10.
　なお、制御プログラムや処理条件データ等が記録されたレシピは、コンピュータ読み取り可能な記録媒体３４に格納された状態のものであってもよい。記録媒体３４としては、例えば、ＣＤ−ＲＯＭ、ハードディスク、フレキシブルディスク、フラッシュメモリを用いることができる。さらに、レシピは、他の装置から専用回線等を介して伝送されてきたものを用いてもよい。 Note that the recipe in which the control program, processing condition data, and the like are recorded may be stored in a computer-readable recording medium 34. As the recording medium 34, for example, a CD-ROM, a hard disk, a flexible disk, or a flash memory can be used. Furthermore, a recipe that has been transmitted from another device via a dedicated line or the like may be used.
　上述したレーザ光加熱装置１０では、ウエハＷの表面に形成された触媒金属層へ赤外線レーザ光を照射して該触媒金属層の表面を溶融し、該触媒金属層へ炭素原子を固溶させた後、触媒金属層を冷却して炭素結晶を析出させてグラフェンを生成する。 In the laser beam heating apparatus 10 described above, the catalytic metal layer formed on the surface of the wafer W is irradiated with infrared laser light to melt the surface of the catalytic metal layer, and carbon atoms are dissolved in the catalytic metal layer. Thereafter, the catalyst metal layer is cooled to precipitate carbon crystals to generate graphene.
　図４は、本実施の形態に係るグラフェンの生成方法を示す工程図である。 FIG. 4 is a process diagram showing a method for producing graphene according to the present embodiment.
　図４において、まず、シリコン基部３５の上に酸化珪素（例えば、ＳｉＯ２）層３６、窒化膜（例えば、ＴｉＮ）層３７及び触媒金属層３８がこの順で積層されたウエハＷを準備し（図４の（Ａ））、レーザ光加熱装置１０のゲートバルブ２０を開弁して搬出入口１９からウエハＷをチャンバ１１の内部に搬入し、載置台１２上に載置する。ウエハＷの触媒金属層３８を構成する金属としては、Ｃｕ、Ｆｅ、Ｃｏ、Ｎｉ、Ｒｕ、Ａｕ等の遷移金属、又はこれらの遷移金属を含む合金が該当する。触媒金属層３８は、スパッタリング、蒸着法、ＣＶＤ法、めっき等の公知の成膜技術によって形成される。なお、ウエハＷは、シリコン基板ではなく、ガラス基板やプラスチック（高分子）基板等であってもよい。 In FIG. 4, first, a wafer W is prepared in which a silicon oxide (eg, SiO 2 ) layer 36, a nitride film (eg, TiN) layer 37, and a catalytic metal layer 38 are laminated in this order on a silicon base 35 ( 4A), the gate valve 20 of the laser beam heating apparatus 10 is opened, and the wafer W is loaded into the chamber 11 from the loading / unloading port 19 and mounted on the mounting table 12. FIG. As a metal constituting the catalytic metal layer 38 of the wafer W, transition metals such as Cu, Fe, Co, Ni, Ru, Au, or alloys containing these transition metals are applicable. The catalytic metal layer 38 is formed by a known film formation technique such as sputtering, vapor deposition, CVD, or plating. The wafer W may be a glass substrate, a plastic (polymer) substrate, or the like instead of the silicon substrate.
　次いで、ガス供給部１４のガスノズル５４が触媒金属層３８へ向けて炭素含有ガス、水素含有ガス及び不活性ガスの混合ガスを供給し、混合ガスの供給を継続しながら、レーザ光照射部１３がウエハＷの触媒金属層３８へ向けて赤外線レーザ光Ｌを照射する（図４の（Ｂ））。混合ガス中の炭素含有ガスとしては、ＣＨ４ガス、Ｃ２Ｈ４ガス又はＣ２Ｈ２ガス等が好ましく、混合ガス中の水素含有ガスとしては、Ｈ２ガス又はＮＨ３ガスが好ましく、混合ガス中の不活性ガスとしては、Ａｒガス、Ｈｅガス又はＮ２ガスが好ましい。また、混合ガスの供給及び赤外線レーザ光Ｌの照射は同時に開始してもよい。なお、本実施の形態では、触媒金属層３８において赤外線レーザ光Ｌが照射する箇所を照射箇所という。 Next, the gas nozzle 54 of the gas supply unit 14 supplies a mixed gas of carbon-containing gas, hydrogen-containing gas, and inert gas toward the catalyst metal layer 38, and the laser beam irradiation unit 13 continues to supply the mixed gas. Infrared laser light L is irradiated toward the catalytic metal layer 38 of the wafer W ((B) of FIG. 4). The carbon-containing gas in the mixed gas is preferably CH 4 gas, C 2 H 4 gas, C 2 H 2 gas or the like, and the hydrogen-containing gas in the mixed gas is preferably H 2 gas or NH 3 gas, and mixed As the inert gas in the gas, Ar gas, He gas or N 2 gas is preferable. Further, the supply of the mixed gas and the irradiation with the infrared laser beam L may be started simultaneously. In the present embodiment, a portion irradiated with the infrared laser light L in the catalytic metal layer 38 is referred to as an irradiation portion.
　触媒金属層３８へ向けて供給された混合ガス中の水素含有ガスは、赤外線レーザ光Ｌの照射による加熱によって触媒金属層３８の表面における酸化薄膜（例えば、自然酸化膜）を還元して触媒金属層３８の照射箇所における表面を活性化する。また、混合ガス中の炭素含有ガスは赤外線レーザ光Ｌの照射による加熱によって炭素原子や他の原子へ分解される。さらに、赤外線レーザ光Ｌの照射による加熱によって触媒金属層３８の温度が上昇して触媒金属層３８が溶融し、触媒金属層３８の溶解度も向上するため、炭素含有ガスが分解されて生じた炭素原子が触媒金属層３８へ固溶する。 The hydrogen-containing gas in the mixed gas supplied toward the catalyst metal layer 38 reduces the oxide thin film (for example, a natural oxide film) on the surface of the catalyst metal layer 38 by heating by irradiation with the infrared laser beam L, thereby reducing the catalyst metal. The surface of the layer 38 at the irradiated position is activated. Further, the carbon-containing gas in the mixed gas is decomposed into carbon atoms and other atoms by heating by irradiation with the infrared laser beam L. Furthermore, since the temperature of the catalytic metal layer 38 is increased by heating by irradiation with the infrared laser beam L, the catalytic metal layer 38 is melted, and the solubility of the catalytic metal layer 38 is also improved. Atoms are dissolved in the catalytic metal layer 38.
　一般に、赤外線レーザ光Ｌは出力、照射時間を正確に調整することができるので、触媒金属層３８の温度を所望の温度に容易に維持することができる。したがって、図４のグラフェンの生成方法では、上述した赤外線レーザ光Ｌの特性を利用して触媒金属層３８へ炭素原子を所望量だけ固溶させる。具体的には、出力が１００~１００００Ｗの赤外線レーザ光Ｌの照射箇所への照射を数ミリ秒、例えば、０．００１~１０００ｍｓｅｃだけ継続することにより、照射箇所の温度を３００~９００℃、好ましくは、４００~６００℃へ昇温させて触媒金属層３８へ炭素原子を所望量だけ固溶させる。なお、赤外線レーザ光Ｌの照射は触媒金属層３８への炭素原子の固溶が飽和する前に停止するのが好ましい。また、触媒金属層３８へ炭素原子を固溶させる際、チャンバ１１の内部をヒータ（図示しない）によって加熱し、照射箇所の温度を、例えば、室温~６００℃、好ましくは、３００℃~４００℃まで上昇させてもよい。その結果、赤外線レーザ光Ｌの照射による照射箇所の昇温幅を小さくすることができるため、赤外線レーザ光Ｌの照射による昇温の制御性を向上させることができ、照射箇所の昇温制御を緻密に行うことができる。 Generally, since the output and irradiation time of the infrared laser beam L can be accurately adjusted, the temperature of the catalyst metal layer 38 can be easily maintained at a desired temperature. Therefore, in the graphene generation method of FIG. 4, a desired amount of carbon atoms is dissolved in the catalytic metal layer 38 using the characteristics of the infrared laser beam L described above. Specifically, the irradiation site is irradiated for several milliseconds, for example, 0.001 to 1000 msec, and the temperature of the irradiation site is preferably 300 to 900 ° C., preferably 100 to 10,000 W. , Raise the temperature to 400 to 600 ° C., and cause the catalyst metal layer 38 to dissolve in a desired amount of carbon atoms. The irradiation with the infrared laser beam L is preferably stopped before the solid solution of carbon atoms in the catalytic metal layer 38 is saturated. Further, when carbon atoms are dissolved in the catalytic metal layer 38, the inside of the chamber 11 is heated by a heater (not shown), and the temperature of the irradiated portion is, for example, room temperature to 600 ° C., preferably 300 ° C. to 400 ° C. May be raised. As a result, it is possible to reduce the temperature rise width of the irradiated part by the irradiation with the infrared laser beam L, so that the controllability of the temperature rise by the irradiation with the infrared laser beam L can be improved, and the temperature rise control of the irradiation part can be performed. It can be done precisely.
　次いで、赤外線レーザ光Ｌの照射を数ミリ秒だけ継続させた後、赤外線レーザ光Ｌの照射を停止する。これにより、触媒金属層３８が冷却されるが、赤外線レーザ光Ｌの照射の停止によって触媒金属層３８への熱の供給を直ちに停止することができ、もって、触媒金属層３８を急冷して触媒金属層３８へ所望量以上の炭素原子が固溶するのを防止することができる。このとき、触媒金属層３８の温度低下に伴う溶解度の低下により、触媒金属層３８へ固溶した炭素原子が飽和して炭素結晶が析出し、照射箇所においてグラフェン３９が生成される。なお、赤外線レーザ光Ｌの照射の停止による触媒金属層３８の冷却時間は、５秒以内、好ましくは、３秒以内である。 Next, after irradiation of the infrared laser beam L is continued for several milliseconds, the irradiation of the infrared laser beam L is stopped. As a result, the catalyst metal layer 38 is cooled, but the supply of heat to the catalyst metal layer 38 can be stopped immediately by stopping the irradiation of the infrared laser light L, and the catalyst metal layer 38 is rapidly cooled to It is possible to prevent a desired amount or more of carbon atoms from dissolving in the metal layer 38. At this time, due to a decrease in solubility accompanying a decrease in temperature of the catalyst metal layer 38, carbon atoms dissolved in the catalyst metal layer 38 are saturated and carbon crystals are precipitated, and graphene 39 is generated at the irradiated portion. The cooling time of the catalytic metal layer 38 by stopping the irradiation with the infrared laser beam L is within 5 seconds, preferably within 3 seconds.
　以上、図４のグラフェンの生成方法によれば、触媒金属層３８へは所望量の炭素原子のみが固溶するので、析出する炭素結晶の量は所望量に対応した量となり、もって、生成されるグラフェン３９の炭素原子層４０の層数も所望量に対応した数となる。すなわち、図４のグラフェンの生成方法では、触媒金属層３８へ所望量の炭素原子を正確に固溶させることができ、その結果、触媒金属層３８から析出する炭素結晶の量を正確に制御することができ、もって、生成されるグラフェン３９の炭素原子層４０の層数を確実に制御することができる。 As described above, according to the graphene generation method of FIG. 4, only a desired amount of carbon atoms is dissolved in the catalytic metal layer 38, so that the amount of precipitated carbon crystals is an amount corresponding to the desired amount, and thus generated. The number of carbon atom layers 40 of graphene 39 is also a number corresponding to a desired amount. That is, in the graphene generation method of FIG. 4, a desired amount of carbon atoms can be accurately dissolved in the catalyst metal layer 38, and as a result, the amount of carbon crystals precipitated from the catalyst metal layer 38 is accurately controlled. Therefore, the number of carbon atom layers 40 of the generated graphene 39 can be reliably controlled.
　また、図４のグラフェンの生成方法では、グラフェン３９を生成する際、炭素結晶を析出させるため、アモルファスカーボンが発生するのを抑制することができ、もって、グラフェン３９の抵抗率が高まるのを防止することができる。 In addition, in the graphene generation method of FIG. 4, when generating graphene 39, since carbon crystals are precipitated, it is possible to suppress the generation of amorphous carbon, thereby preventing the resistivity of graphene 39 from increasing. can do.
　さらに、図４のグラフェンの生成方法では、赤外線レーザ光Ｌの照射を数ミリ秒だけしか継続しないので、触媒金属層３８が過剰に加熱されて当該触媒金属層３８の表面形状が崩れることがない。その結果、触媒金属層３８の表面において炭素結晶を均一に析出させることができ、もって、均一な厚さのグラフェン３９を得ることができる。 Further, in the graphene generation method of FIG. 4, since the irradiation with the infrared laser beam L is continued only for several milliseconds, the catalytic metal layer 38 is not excessively heated and the surface shape of the catalytic metal layer 38 is not destroyed. . As a result, carbon crystals can be uniformly deposited on the surface of the catalytic metal layer 38, and thus graphene 39 having a uniform thickness can be obtained.
　ところで、触媒金属層３８のおける照射箇所は赤外線レーザ光Ｌのスポットに対応するため、上述した赤外線レーザ光Ｌの照射及び照射の停止を行うと、触媒金属層３８において赤外線レーザ光Ｌのスポットに対応する面積だけグラフェン３９が生成される。 By the way, since the irradiation spot in the catalyst metal layer 38 corresponds to the spot of the infrared laser beam L, when the irradiation of the infrared laser beam L and the stop of the irradiation are performed, the spot of the infrared laser beam L in the catalyst metal layer 38 is obtained. Graphene 39 is generated in the corresponding area.
　これに対応して、本実施の形態では、一の照射箇所においてグラフェン３９が生成された後、赤外線レーザ光Ｌを赤外線レーザ光Ｌのスポット径分だけウエハＷの表面と平行（図４の（Ｂ）中の黒矢印方向）に移動させて図４のグラフェンの生成方法の実行を繰り返す。すなわち、赤外線レーザ光Ｌによって触媒金属層３８を走査するので、触媒金属層３８の広範囲において当該触媒金属層３８へ所望量の炭素原子を正確に固溶させることができ、もって、広範囲に亘ってグラフェン３９が生成される際、炭素原子層４０の層数を確実に制御することができる。 Correspondingly, in the present embodiment, after the graphene 39 is generated at one irradiation location, the infrared laser light L is parallel to the surface of the wafer W by the spot diameter of the infrared laser light L ((( B) in the direction of the black arrow in FIG. 4 and the execution of the graphene generation method of FIG. 4 is repeated. That is, since the catalyst metal layer 38 is scanned by the infrared laser beam L, a desired amount of carbon atoms can be accurately dissolved in the catalyst metal layer 38 in a wide range of the catalyst metal layer 38, and thus, over a wide range. When the graphene 39 is generated, the number of the carbon atom layers 40 can be reliably controlled.
　チャンバ１１の内部の圧力は、炭素含有ガスの分圧を上昇させて炭素原子の固溶を促進する観点から、例えば、１３~１３３３Ｐａとすることが好ましく、６６~６６６Ｐａがより好ましい。 The pressure inside the chamber 11 is preferably 13 to 1333 Pa, and more preferably 66 to 666 Pa, from the viewpoint of increasing the partial pressure of the carbon-containing gas to promote solid solution of carbon atoms.
　また、混合ガス中の炭素含有ガスの流量は、炭素原子を多く供給していち早く触媒金属層３８へ炭素原子を固溶させる観点から、例えば、１~１００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、５~５０ｍＬ／分（ｓｃｃｍ）がより好ましい。 Further, the flow rate of the carbon-containing gas in the mixed gas is preferably set to, for example, 1 to 100 mL / min (sccm) from the viewpoint of supplying a large amount of carbon atoms and quickly dissolving the carbon atoms in the catalytic metal layer 38. 5 to 50 mL / min (sccm) is more preferable.
　次に、本発明の第２の実施の形態に係るグラフェンの生成方法について説明する。 Next, a method for generating graphene according to the second embodiment of the present invention will be described.
　本実施の形態は、その構成や作用が上述した第１の実施の形態と基本的に同じであり、炭素含有ガスを供給する代わりに炭素含有層を形成する点で上述した第１の実施の形態と異なる。したがって、重複した構成、作用については説明を省略し、以下に異なる構成、作用についての説明を行う。 This embodiment is basically the same in configuration and operation as the first embodiment described above, and the first embodiment described above in that a carbon-containing layer is formed instead of supplying a carbon-containing gas. Different from form. Therefore, the description of the duplicated configuration and operation is omitted, and the description of the different configuration and operation is given below.
　図５は、本実施の形態に係るグラフェンの生成方法を示す工程図である。 FIG. 5 is a process diagram showing a graphene generation method according to the present embodiment.
　図５において、第１の実施の形態におけるウエハと同様の膜構成を有するウエハＷを準備し（図５の（Ａ））、触媒金属層３８の上に厚さが所定値に制御された炭素含有層４１を形成する（図５の（Ｂ））。炭素含有層４１は、蒸着法、ＣＶＤ法、スクリーン法、塗布等の公知の成膜技術によって形成される。 In FIG. 5, a wafer W having a film configuration similar to that of the wafer in the first embodiment is prepared (FIG. 5A), and the carbon whose thickness is controlled to a predetermined value on the catalyst metal layer 38 is prepared. The containing layer 41 is formed ((B) of FIG. 5). The carbon-containing layer 41 is formed by a known film forming technique such as a vapor deposition method, a CVD method, a screen method, or coating.
　次いで、レーザ光加熱装置１０のゲートバルブ２０を開弁して搬出入口１９からウエハＷをチャンバ１１の内部に搬入し、載置台１２上に載置し、レーザ光照射部１３がウエハＷの触媒金属層３８及び炭素含有層４１へ向けて赤外線レーザ光Ｌを照射するとともに、ガス供給部１４のガスノズル５４が触媒金属層３８へ向けて不活性ガスを供給する。 Next, the gate valve 20 of the laser beam heating device 10 is opened, the wafer W is loaded into the chamber 11 from the loading / unloading port 19 and placed on the mounting table 12, and the laser beam irradiation unit 13 is a catalyst for the wafer W. The infrared laser beam L is irradiated toward the metal layer 38 and the carbon-containing layer 41, and the gas nozzle 54 of the gas supply unit 14 supplies an inert gas toward the catalyst metal layer 38.
　このとき、赤外線レーザ光Ｌの照射による加熱によって触媒金属層３８及び炭素含有層４１の温度が上昇して炭素含有層４１が溶融し、且つ触媒金属層３８の溶解度も向上するため、炭素原子が触媒金属層３８へ固溶して炭素固溶体層４２が形成される（図５の（Ｃ））。 At this time, the temperature of the catalytic metal layer 38 and the carbon-containing layer 41 is increased by heating by irradiation with the infrared laser beam L, the carbon-containing layer 41 is melted, and the solubility of the catalytic metal layer 38 is also improved. A carbon solid solution layer 42 is formed by solid solution in the catalyst metal layer 38 ((C) of FIG. 5).
　触媒金属層３８へ固溶される炭素原子は炭素含有層４１から供給されるが、炭素含有層４１の厚さは所定値に制御されているため、触媒金属層３８へ固溶される炭素原子の量は所定値の厚さに対応したものとなり、触媒金属層３８へ所望量以上の炭素原子が固溶することがない。 The carbon atoms dissolved in the catalyst metal layer 38 are supplied from the carbon-containing layer 41. Since the thickness of the carbon-containing layer 41 is controlled to a predetermined value, the carbon atoms dissolved in the catalyst metal layer 38 are controlled. The amount corresponds to a predetermined thickness, and a desired amount or more of carbon atoms does not dissolve in the catalyst metal layer 38.
　本実施の形態においても、赤外線レーザ光Ｌの出力、照射時間を調整することによって触媒金属層３８の温度を所望の温度に維持して触媒金属層３８へ炭素原子を所望量だけ固溶させる。具体的には、出力が１００~１００００Ｗの赤外線レーザ光Ｌの照射箇所への照射を数ミリ秒、例えば、０．００１~１０００ｍｓｅｃだけ継続することにより、照射箇所の温度を３００~９００℃、好ましくは、４００~６００℃へ昇温させる。 Also in the present embodiment, the temperature of the catalytic metal layer 38 is maintained at a desired temperature by adjusting the output of the infrared laser beam L and the irradiation time, and a desired amount of carbon atoms is dissolved in the catalytic metal layer 38 in a desired amount. Specifically, irradiation of the irradiated portion of the infrared laser beam L with an output of 100 to 10000 W is continued for several milliseconds, for example, 0.001 to 1000 msec, so that the temperature of the irradiated portion is 300 to 900 ° C., preferably Raises the temperature to 400 to 600 ° C.
　次いで、赤外線レーザ光Ｌの照射を数ミリ秒だけ継続させた後、赤外線レーザ光Ｌの照射を停止して触媒金属層３８への熱の供給を直ちに停止することにより、触媒金属層３８を急冷して触媒金属層３８へ所望量以上の炭素原子が固溶するのを防止することができる。このときも、触媒金属層３８へ固溶した炭素原子が飽和して炭素結晶が析出し、照射箇所においてグラフェン３９が生成される。 Next, after the irradiation of the infrared laser light L is continued for several milliseconds, the irradiation of the infrared laser light L is stopped and the supply of heat to the catalytic metal layer 38 is immediately stopped, thereby rapidly cooling the catalytic metal layer 38. Thus, it is possible to prevent more than a desired amount of carbon atoms from dissolving in the catalyst metal layer 38. Also at this time, carbon atoms dissolved in the catalytic metal layer 38 are saturated and carbon crystals are precipitated, and graphene 39 is generated at the irradiated portion.
　以上、図５のグラフェンの生成方法によれば、触媒金属層３８へは所望量の炭素原子のみが固溶する。すなわち、図５のグラフェンの生成方法においても、図４のグラフェン方法と同様に、触媒金属層３８へ所望量の炭素原子を正確に固溶させることができ、もって、生成されるグラフェン３９の炭素原子層４０の層数を確実に制御することができる。 As described above, according to the graphene generation method of FIG. 5, only a desired amount of carbon atoms is dissolved in the catalytic metal layer 38. That is, in the graphene generation method of FIG. 5, similarly to the graphene method of FIG. 4, a desired amount of carbon atoms can be accurately dissolved in the catalytic metal layer 38, and thus the carbon of the graphene 39 to be generated The number of atomic layers 40 can be reliably controlled.
　また、本実施の形態でも、第１の実施の形態と同様に、赤外線レーザ光Ｌによって触媒金属層３８の全面を走査して各照射箇所において赤外線レーザ光Ｌを数ミリ秒に亘って照射させる。これにより、触媒金属層３８の広範囲において当該触媒金属層３８へ所望量の炭素原子を正確に固溶させることができる。 Also in the present embodiment, as in the first embodiment, the entire surface of the catalytic metal layer 38 is scanned with the infrared laser light L, and the infrared laser light L is irradiated for several milliseconds at each irradiation location. . Thereby, a desired amount of carbon atoms can be accurately dissolved in the catalytic metal layer 38 in a wide range of the catalytic metal layer 38.
　本実施の形態では、ウエハＷにおいて触媒金属層３８の上に炭素含有層４１を形成したが、触媒金属層３８よりも炭素含有層４１を先に形成することによって炭素含有層４１の上に触媒金属層３８を形成してもよい。 In the present embodiment, the carbon-containing layer 41 is formed on the catalyst metal layer 38 in the wafer W, but the catalyst is formed on the carbon-containing layer 41 by forming the carbon-containing layer 41 before the catalyst metal layer 38. A metal layer 38 may be formed.
　なお、本実施の形態では、赤外線レーザ光Ｌによって炭素含有層４１を溶融させたが、炭素含有層４１をプラズマによって溶融してもよい。この場合、触媒金属層３８の温度を制御するために、ウエハＷにバイアス電圧を印加し、且つ該バイアス電圧を制御することによって触媒金属層３８へ引きこまれるプラズマの量を制御するのが好ましい。 In the present embodiment, the carbon-containing layer 41 is melted by the infrared laser beam L, but the carbon-containing layer 41 may be melted by plasma. In this case, in order to control the temperature of the catalyst metal layer 38, it is preferable to apply a bias voltage to the wafer W and to control the amount of plasma drawn into the catalyst metal layer 38 by controlling the bias voltage. .
　次に、本発明の第３の実施の形態に係るグラフェンの生成方法について説明する。 Next, a method for generating graphene according to the third embodiment of the present invention will be described.
　本実施の形態は、その構成や作用が上述した第１の実施の形態と基本的に同じであり、赤外線レーザ光Ｌによって触媒金属層３８を走査しない点で上述した第１の実施の形態と異なる。したがって、重複した構成、作用については説明を省略し、以下に異なる構成、作用についての説明を行う。 This embodiment is basically the same in configuration and operation as the first embodiment described above, and is different from the first embodiment described above in that the catalytic metal layer 38 is not scanned by the infrared laser light L. Different. Therefore, the description of the duplicated configuration and operation is omitted, and the description of the different configuration and operation is given below.
　図６は、本実施の形態に係るグラフェンの生成方法を示す工程図である。 FIG. 6 is a process diagram showing a graphene generation method according to the present embodiment.
　図６において、第１の実施の形態におけるウエハと同様の膜構成を有するウエハＷを準備し（図６の（Ａ））、レーザ光加熱装置１０のゲートバルブ２０を開弁して搬出入口１９からウエハＷをチャンバ１１の内部に搬入し、載置台１２上に載置する。 In FIG. 6, a wafer W having a film configuration similar to that of the wafer in the first embodiment is prepared (FIG. 6A), the gate valve 20 of the laser beam heating device 10 is opened, and the carry-in / out port 19 is opened. Then, the wafer W is loaded into the chamber 11 and placed on the mounting table 12.
　次いで、赤外線レーザ光Ｌによって触媒金属層３８の全域を走査することなく、レーザ光照射部１３からウエハＷの触媒金属層３８の所定の箇所のみへ向けて赤外線レーザ光Ｌを照射する。これにより、所定の箇所において加熱に因るマイグレーションが発生し、触媒金属層３８を構成している金属原子の凝集が生じて突起状のステップ４３が生じる（図６の（Ｂ））。なお、ステップ４３の突出量は赤外線レーザ光Ｌの照射時間に応じて変化するため、本実施の形態では、赤外線レーザ光Ｌの照射時間を調整してステップ４３の突出量を所望値へ調整する。 Next, the infrared laser beam L is irradiated from the laser beam irradiation unit 13 toward only a predetermined portion of the catalyst metal layer 38 of the wafer W without scanning the entire area of the catalyst metal layer 38 with the infrared laser beam L. As a result, migration due to heating occurs at a predetermined location, aggregation of metal atoms constituting the catalytic metal layer 38 occurs, and a protruding step 43 is generated ((B) of FIG. 6). In addition, since the protrusion amount of step 43 changes according to the irradiation time of the infrared laser beam L, in this embodiment, the irradiation time of the infrared laser beam L is adjusted to adjust the protrusion amount of step 43 to a desired value. .
　このとき、ガス供給部１４のガスノズル５４が触媒金属層３８へ向けて炭素含有ガス、水素含有ガス及び不活性ガスの混合ガスを供給する。供給された混合ガス中の水素含有ガスは、赤外線レーザ光Ｌの照射による加熱によってステップ４３の表面を還元して活性化する。また、混合ガス中の炭素含有ガスは赤外線レーザ光Ｌの照射による加熱によって炭素原子や他の原子へ分解される。ここで、ステップ４３も赤外線レーザ光Ｌの照射による加熱によって温度が上昇し、溶解度が向上しているため、炭素原子がステップ４３へ固溶する。なお、赤外線レーザ光Ｌはステップ４３の形成、及び混合ガスの供給にかけて連続して照射されてもよく、ステップ４３が形成された後、一旦、赤外線レーザ光Ｌの照射を停止し、混合ガスの供給が開始された後に、再度、赤外線レーザ光Ｌの照射を行ってもよい。 At this time, the gas nozzle 54 of the gas supply unit 14 supplies a mixed gas of carbon-containing gas, hydrogen-containing gas, and inert gas toward the catalyst metal layer 38. The hydrogen-containing gas in the supplied mixed gas is activated by reducing the surface of step 43 by heating by irradiation with infrared laser light L. Further, the carbon-containing gas in the mixed gas is decomposed into carbon atoms and other atoms by heating by irradiation with the infrared laser beam L. Here, also in step 43, the temperature rises due to heating by irradiation with the infrared laser beam L, and the solubility is improved, so that the carbon atoms are dissolved in step 43. The infrared laser light L may be continuously irradiated through the formation of Step 43 and the supply of the mixed gas. After Step 43 is formed, the irradiation of the infrared laser light L is temporarily stopped and the mixed gas is supplied. After the supply is started, the infrared laser beam L may be irradiated again.
　炭素原子をステップ４３へ固溶させる際、本実施の形態でも、第１の実施の形態と同様に、赤外線レーザ光Ｌの照射時間を調整して触媒金属層３８へ炭素原子を所望量だけ固溶させる。具体的には、出力が１００~１００００Ｗの赤外線レーザ光Ｌのステップ４３への照射を数ミリ秒、例えば、０．００１~１０００ｍｓｅｃだけ継続することにより、ステップ４３の温度を３００~９００℃、好ましくは、４００~６００℃へ昇温させてステップ４３へ炭素原子を所望量だけ固溶させる。なお、赤外線レーザ光Ｌの照射はステップ４３への炭素原子の固溶が飽和する前に停止するのが好ましい。 When the carbon atoms are dissolved in step 43, in this embodiment as well, as in the first embodiment, the irradiation time of the infrared laser light L is adjusted to fix the carbon atoms in the catalyst metal layer 38 by a desired amount. Dissolve. Specifically, the irradiation of step 43 with infrared laser light L having an output of 100 to 10000 W is continued for several milliseconds, for example, 0.001 to 1000 msec, whereby the temperature of step 43 is preferably 300 to 900 ° C., preferably Raises the temperature to 400 to 600 ° C. and causes step 43 to dissolve the carbon atom in a desired amount. The irradiation with the infrared laser beam L is preferably stopped before the solid solution of carbon atoms in step 43 is saturated.
　次いで、赤外線レーザ光Ｌの照射を数ミリ秒だけ継続させた後、赤外線レーザ光Ｌの照射を停止する。このとき、赤外線レーザ光Ｌの照射の停止によってステップ４３への熱の供給を直ちに停止することができ、もって、ステップ４３を急冷してステップ４３へ所望量以上の炭素原子が固溶するのを防止することができる。その後、ステップ４３の温度低下に伴う溶解度の低下により、ステップ４３へ固溶した炭素原子が飽和してステップ４３の表面から炭素結晶が析出し、ステップ４３からグラフェン３９が成長する。 Next, after irradiation of the infrared laser beam L is continued for several milliseconds, the irradiation of the infrared laser beam L is stopped. At this time, by stopping the irradiation of the infrared laser beam L, the supply of heat to the step 43 can be stopped immediately, so that the step 43 is rapidly cooled so that a desired amount or more of carbon atoms dissolve in the step 43. Can be prevented. Thereafter, due to the decrease in solubility accompanying the temperature decrease in step 43, the carbon atoms dissolved in step 43 are saturated, carbon crystals are precipitated from the surface of step 43, and graphene 39 grows from step 43.
　以上、図６のグラフェンの生成方法によれば、ステップ４３には所望量の炭素原子のみが固溶するので、析出する炭素結晶の量は所望量に対応した量となり、もって、成長するグラフェン３９の炭素原子層４０の層数を確実に制御することができる。 As described above, according to the graphene generation method of FIG. 6, since only a desired amount of carbon atoms is dissolved in Step 43, the amount of precipitated carbon crystals corresponds to the desired amount, and thus grows graphene 39. The number of the carbon atom layers 40 can be reliably controlled.
　また、ステップ４３からグラフェン３９が成長する場合、グラフェン３９は触媒金属層３８の表面に沿って成長するため、グラフェン３９の炭素原子層４０の層数はステップ４３の突出量に比例する。したがって、図６のグラフェンの生成方法において、赤外線レーザ光Ｌの照射時間を調整してステップ４３の突出量を所望値へ調整することによっても、グラフェン３９の炭素原子層４０の層数を確実に制御することができる。 Further, when the graphene 39 grows from the step 43, the graphene 39 grows along the surface of the catalytic metal layer 38, so the number of the carbon atom layers 40 of the graphene 39 is proportional to the protrusion amount of the step 43. Therefore, in the graphene generation method of FIG. 6, the number of carbon atom layers 40 of the graphene 39 can be reliably increased by adjusting the irradiation time of the infrared laser light L and adjusting the protrusion amount in step 43 to a desired value. Can be controlled.
　さらに、図６のグラフェンの生成方法では、赤外線レーザ光Ｌによって触媒金属層３８を走査しないため、ステップ４３以外の触媒金属層３８の温度は上昇することがなく、ステップ４３において炭素原子が触媒金属層３８へ固溶することがない。これにより、ステップ４３以外からグラフェン３９が成長するのを防止することができる。したがって、ステップ４３を生じさせる箇所を選択することにより、グラフェン３９が成長する箇所を調整することができる。 Further, in the graphene generation method of FIG. 6, since the catalytic metal layer 38 is not scanned by the infrared laser light L, the temperature of the catalytic metal layer 38 other than step 43 does not rise. There is no solid solution in the layer 38. Thereby, it is possible to prevent the graphene 39 from growing from other than step 43. Therefore, by selecting the location where the step 43 is generated, the location where the graphene 39 grows can be adjusted.
　なお、チャンバ１１の内部の圧力は、炭素含有ガスの分圧を上昇させて炭素原子の固溶を促進する観点から、例えば、１３~１３３３Ｐａとすることが好ましく、６６~６６６Ｐａがより好ましい。 The pressure inside the chamber 11 is preferably 13 to 1333 Pa and more preferably 66 to 666 Pa from the viewpoint of increasing the partial pressure of the carbon-containing gas and promoting solid solution of carbon atoms.
　また、混合ガス中の炭素含有ガスの流量は、炭素原子を多く供給していち早くステップ４３へ炭素原子を固溶させる観点から、例えば、１~１００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、５~５０ｍＬ／分（ｓｃｃｍ）がより好ましい。 Further, the flow rate of the carbon-containing gas in the mixed gas is preferably set to, for example, 1 to 100 mL / min (sccm) from the viewpoint of supplying a large amount of carbon atoms and promptly dissolving the carbon atoms in step 43. ~ 50 mL / min (sccm) is more preferred.
　図６のグラフェンの生成方法では、ウエハＷの表面を触媒金属層３８が全面的に覆うが、ステップ４３を生じさせる箇所にのみ触媒金属層３８を形成してもよい。また、ステップ４３の表面から炭素結晶が析出させる際、赤外線レーザ光Ｌの照射を停止させてステップ４３を急冷したが、赤外線レーザ光Ｌの照射を停止することなく、混合ガスの供給を継続してステップ４３において固溶する炭素原子を飽和させて炭素結晶を析出させてもよい。 6, the catalytic metal layer 38 covers the entire surface of the wafer W, but the catalytic metal layer 38 may be formed only at the location where the step 43 is generated. Further, when the carbon crystal is precipitated from the surface of Step 43, the irradiation of the infrared laser light L is stopped and the step 43 is rapidly cooled. However, the supply of the mixed gas is continued without stopping the irradiation of the infrared laser light L. In step 43, carbon atoms that are solid solution may be saturated to precipitate carbon crystals.
　次に、本発明の第４の実施の形態に係るカーボンナノチューブの成長方法について説明する。 Next, a carbon nanotube growth method according to the fourth embodiment of the present invention will be described.
　本実施の形態では、上述した各実施の形態と重複した構成、作用については説明を省略し、以下に異なる構成、作用についての説明を行う。 In the present embodiment, the description of the same configuration and operation as those of the above-described embodiments will be omitted, and different configurations and operations will be described below.
　本実施の形態では、ウエハＷの表面に形成された触媒金属層へ赤外線レーザ光を照射して微細な金属微粒子を形成し、赤外線レーザ光によって炭素含有ガスを炭素原子に分解し、微細な金属微粒子を核として炭素原子を再結晶させてカーボンナノチューブを成長させる。 In the present embodiment, fine metal particles are formed by irradiating the catalytic metal layer formed on the surface of the wafer W with infrared laser light, and the carbon-containing gas is decomposed into carbon atoms by the infrared laser light. Carbon nanotubes are grown by recrystallizing carbon atoms using fine particles as nuclei.
　図７は、本実施の形態に係るカーボンナノチューブの成長方法を示す工程図である。 FIG. 7 is a process diagram showing a carbon nanotube growth method according to the present embodiment.
　図７において、まず、第１の実施の形態におけるウエハと同様の膜構成を有するウエハＷを準備する（図７の（Ａ））。 In FIG. 7, first, a wafer W having the same film configuration as that of the wafer in the first embodiment is prepared (FIG. 7A).
　次いで、レーザ光照射部１３がウエハＷの触媒金属層３８へ向けて赤外線レーザ光Ｌを照射する。赤外線レーザ光Ｌは触媒金属層３８へ熱エネルギーを付与し、熱エネルギーが付与された触媒金属層３８の表面ではマイグレーションが発生し、触媒金属層３８の触媒金属の原子の凝集が生じて触媒金属微粒子４４が形成される（図７の（Ｂ））。 Next, the laser beam irradiation unit 13 irradiates the infrared laser beam L toward the catalytic metal layer 38 of the wafer W. The infrared laser beam L imparts thermal energy to the catalytic metal layer 38, migration occurs on the surface of the catalytic metal layer 38 to which thermal energy has been imparted, and aggregation of catalytic metal atoms in the catalytic metal layer 38 occurs, resulting in catalytic metal. Fine particles 44 are formed (FIG. 7B).
　一般に、赤外線レーザ光Ｌは出力、照射時間を正確に調整することができるので、触媒金属層３８における照射箇所へ付与する熱エネルギーの量を正確に制御することができる。したがって、図７のカーボンナノチューブの成長方法では、上述した赤外線レーザ光Ｌの特性を利用して触媒金属層３８へ付与する熱エネルギーの量を調整する。具体的には、出力が１００~１００００Ｗの赤外線レーザ光Ｌの照射箇所への照射を数ミリ秒、例えば、０．００１~１０００ｍｓｅｃだけ継続することにより、照射箇所の温度を３００~９００℃、好ましくは、４００~６００℃へ昇温させて触媒金属層３８の表面に発生するマイグレーションの程度を制御し、触媒金属の原子の凝集の程度を所望の値に制御する。これにより、所望の大きさの触媒金属微粒子４４を形成することができる。 In general, since the output and irradiation time of the infrared laser beam L can be accurately adjusted, the amount of thermal energy applied to the irradiated portion in the catalytic metal layer 38 can be accurately controlled. Therefore, in the carbon nanotube growth method of FIG. 7, the amount of thermal energy applied to the catalytic metal layer 38 is adjusted using the characteristics of the infrared laser light L described above. Specifically, the irradiation site is irradiated for several milliseconds, for example, 0.001 to 1000 msec, and the temperature of the irradiation site is preferably 300 to 900 ° C., preferably 100 to 10,000 W. Controls the degree of migration that occurs on the surface of the catalyst metal layer 38 by raising the temperature to 400 to 600 ° C., and controls the degree of aggregation of the atoms of the catalyst metal to a desired value. Thereby, catalyst metal fine particles 44 having a desired size can be formed.
　赤外線レーザ光Ｌを触媒金属層３８における照射箇所へ照射する際、ガス供給部１４はチャンバ１１の内部へ混合ガスを噴出する。混合ガスはガス供給源２４から供給されるが、混合ガスは不活性ガス、例えば、Ｎ２ガス、Ｈｅガス、若しくはＡｒガスのみを含んでもよく、不活性ガスに加えて水素含有ガス、例えば、Ｈ２ガスやＮＨ３ガスを含んでいてもよい。特に、水素含有ガスを含む場合、赤外線レーザ光Ｌによる加熱によって水素含有ガスから生じる水素原子は触媒金属微粒子４４の表面を還元し、触媒金属微粒子４４の活性化を行う。 When the infrared laser beam L is irradiated to the irradiated portion in the catalytic metal layer 38, the gas supply unit 14 ejects the mixed gas into the chamber 11. The mixed gas is supplied from the gas supply source 24, but the mixed gas may contain only an inert gas, for example, N 2 gas, He gas, or Ar gas. In addition to the inert gas, a hydrogen-containing gas, for example, H 2 gas and NH 3 gas may contain. In particular, when a hydrogen-containing gas is included, hydrogen atoms generated from the hydrogen-containing gas by heating with the infrared laser beam L reduce the surface of the catalyst metal fine particles 44 and activate the catalyst metal fine particles 44.
　このとき、チャンバ１１の内部の圧力は、溶融した触媒金属層３８の蒸発を抑制する観点から、例えば、１３~１３３３Ｐａとすることが好ましく、６６~６６６Ｐａがより好ましい。 At this time, the pressure inside the chamber 11 is preferably 13 to 1333 Pa, and more preferably 66 to 666 Pa, from the viewpoint of suppressing evaporation of the molten catalyst metal layer 38.
　また、混合ガス中の水素含有ガスの流量は、水素原子を多く供給して形成された触媒金属微粒子４４を確実に活性化させる観点から、例えば、１~１００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、５~５０ｍＬ／分（ｓｃｃｍ）がより好ましい。 The flow rate of the hydrogen-containing gas in the mixed gas is, for example, 1 to 100 mL / min (sccm) from the viewpoint of reliably activating the catalytic metal fine particles 44 formed by supplying a large amount of hydrogen atoms. 5 to 50 mL / min (sccm) is more preferable.
　ところで、赤外線レーザ光Ｌの触媒金属層３８における照射箇所への照射を無期限に継続すると、付与される熱エネルギーの量が増大してマイグレーションが促進されて触媒金属の原子の凝集が過度に進行し、その結果、触媒金属微粒子４４の大きさが所望値を超えるおそれがある。 By the way, if irradiation of the infrared laser beam L to the irradiated portion of the catalytic metal layer 38 is continued indefinitely, the amount of applied thermal energy increases, migration is promoted, and the aggregation of catalytic metal atoms proceeds excessively. As a result, the size of the catalyst metal fine particles 44 may exceed a desired value.
　これに対して、図７のカーボンナノチューブの成長方法では、触媒金属微粒子４４の大きさが所望値に達した時点で、赤外線レーザ光Ｌの触媒金属層３８への照射を停止する。赤外線レーザ光Ｌの照射の停止によって触媒金属層３８への熱エネルギーの付与を直ちに停止することができ、もって、触媒金属の原子の凝集を直ちに停止することができる。その結果、触媒金属微粒子４４の成長を直ちに停止して触媒金属微粒子４４の大きさが所望値を超えるのを防止することができる。 On the other hand, in the carbon nanotube growth method of FIG. 7, when the size of the catalytic metal fine particles 44 reaches a desired value, the irradiation of the infrared laser light L onto the catalytic metal layer 38 is stopped. By stopping the irradiation with the infrared laser beam L, the application of thermal energy to the catalytic metal layer 38 can be stopped immediately, and the aggregation of the catalytic metal atoms can be stopped immediately. As a result, the growth of the catalyst metal fine particles 44 can be immediately stopped to prevent the size of the catalyst metal fine particles 44 from exceeding a desired value.
　触媒金属微粒子４４の大きさが所望値に達した否かの判定は、予め触媒金属微粒子４４の大きさが所望値に達するまでの時間を計測し、該時間が経過したか否かに基いて行われるが、判定の方法はこれに限られず、例えば、ＳＥＭで触媒金属微粒子４４の大きさを直接確認して判定を行ってもよい。 The determination as to whether or not the size of the catalyst metal fine particles 44 has reached the desired value is based on whether or not the time until the size of the catalyst metal fine particles 44 reaches the desired value is measured in advance. However, the determination method is not limited to this. For example, the determination may be performed by directly confirming the size of the catalytic metal fine particles 44 with an SEM.
　このとき、触媒金属微粒子４４の大きさとしては、例えば、１~５０ｎｍ程度が好ましい。触媒金属層３８の最初の膜厚が薄いほど、凝集される触媒金属の原子の量も減少し、形成される触媒金属微粒子４４の直径も小さくなる。例えば、触媒金属層３８の膜厚が１ｎｍの場合、形成される触媒金属微粒子４４の直径は１０ｎｍ程度であり、触媒金属層３８の膜厚が２ｎｍの場合、形成される触媒金属微粒子４４の直径は２０ｎｍ程度である。 At this time, the size of the catalytic metal fine particles 44 is preferably about 1 to 50 nm, for example. As the initial film thickness of the catalyst metal layer 38 is thinner, the amount of atoms of the catalyst metal to be aggregated is reduced, and the diameter of the formed catalyst metal fine particles 44 is also reduced. For example, when the thickness of the catalytic metal layer 38 is 1 nm, the diameter of the formed catalytic metal fine particles 44 is about 10 nm, and when the thickness of the catalytic metal layer 38 is 2 nm, the diameter of the formed catalytic metal fine particles 44. Is about 20 nm.
　ところで、触媒金属層３８における照射箇所は赤外線レーザ光Ｌのスポットに対応するため、上述した赤外線レーザ光Ｌの照射及び照射の停止を行うと、触媒金属層３８において赤外線レーザ光Ｌのスポットに対応する面積だけ触媒金属微粒子４４が生成される。 By the way, since the irradiation location in the catalytic metal layer 38 corresponds to the spot of the infrared laser beam L, when the irradiation of the infrared laser beam L and the stop of the irradiation are performed, the catalytic metal layer 38 corresponds to the spot of the infrared laser beam L. The catalytic metal fine particles 44 are generated by the area to be used.
　これに対応して、本実施の形態では、一の照射箇所において触媒金属微粒子４４が生成された後、赤外線レーザ光Ｌを赤外線レーザ光Ｌのスポット径分だけウエハＷの表面と平行（図７の（Ｂ）中の黒矢印方向）に移動させて赤外線レーザ光Ｌの照射及び照射の停止を繰り返す。すなわち、赤外線レーザ光Ｌによって触媒金属層３８を走査するので、触媒金属層３８の広範囲において触媒金属微粒子４４を生成することができる。特に、赤外線レーザ光Ｌの出力、照射時間を均一にすることによって各照射箇所へ付与する熱エネルギーの量を均一にすることにより、各照射箇所における触媒金属の原子の凝集の程度を同じにすることができ、触媒金属層３８の広範囲において均一な大きさの触媒金属微粒子４４を生成することができる。 Correspondingly, in the present embodiment, after the catalytic metal fine particles 44 are generated at one irradiation location, the infrared laser light L is parallel to the surface of the wafer W by the spot diameter of the infrared laser light L (FIG. 7). (B) in the direction of the black arrow), the irradiation of the infrared laser beam L and the stop of the irradiation are repeated. That is, since the catalyst metal layer 38 is scanned by the infrared laser beam L, the catalyst metal fine particles 44 can be generated in a wide range of the catalyst metal layer 38. In particular, by making the output of the infrared laser beam L and the irradiation time uniform, the amount of thermal energy applied to each irradiation site is made uniform, so that the degree of aggregation of catalytic metal atoms at each irradiation site is made the same. The catalyst metal fine particles 44 having a uniform size can be generated in a wide range of the catalyst metal layer 38.
　次いで、レーザ光照射部１３が各照射箇所へ向けて赤外線レーザ光Ｌを再度照射するとともに、ガス供給部１４がチャンバ１１の内部へ混合ガスを噴出して各触媒金属微粒子４４へ向けて混合ガスを供給する。ここで、赤外線レーザ光Ｌは、混合ガスが供給されているチャンバ１１の内部である処理空間を介して各照射箇所へ照射される。このとき、混合ガスは、炭素含有ガス、例えば、Ｃ２Ｈ４ガスと、不活性ガス、例えば、Ａｒガスとを含む。このとき、不活性ガスはキャリアガスとして作用する。 Next, the laser beam irradiation unit 13 irradiates the infrared laser beam L again toward each irradiation location, and the gas supply unit 14 ejects a mixed gas into the chamber 11 and then toward the catalytic metal fine particles 44. Supply. Here, the infrared laser light L is irradiated to each irradiation place through a processing space inside the chamber 11 to which the mixed gas is supplied. At this time, the mixed gas includes a carbon-containing gas such as C 2 H 4 gas and an inert gas such as Ar gas. At this time, the inert gas acts as a carrier gas.
　混合ガス中のＣ２Ｈ４ガスは、各照射箇所へ向けて照射された赤外線レーザ光Ｌによって炭素原子に熱分解される。本実施の形態では、熱分解によって生じた炭素原子を用い、各触媒金属微粒子４４を核として炭素原子を再結晶させてカーボンナノチューブ４５を形成する（図７の（Ｃ））。 The C 2 H 4 gas in the mixed gas is thermally decomposed into carbon atoms by the infrared laser beam L irradiated toward each irradiation location. In the present embodiment, carbon atoms generated by thermal decomposition are used to recrystallize carbon atoms with each catalytic metal fine particle 44 as a nucleus to form carbon nanotubes 45 ((C) in FIG. 7).
　カーボンナノチューブ４０を形成する際も、照射箇所へ付与する熱エネルギーの量を調整する。具体的には、出力が１００~１００００Ｗの赤外線レーザ光Ｌを照射することにより、照射箇所の温度を３００~９００℃、好ましくは、４００~６００℃へ昇温させ、さらに、赤外線レーザ光Ｌの照射箇所への照射を数分、例えば、１~６０分に亘って維持することにより、Ｃ２Ｈ４ガスの炭素原子への熱分解を継続し、炭素原子の供給を継続させてカーボンナノチューブ４５の成長を継続させる。また、カーボンナノチューブ４０を形成する際、チャンバ１１の内部をヒータによって加熱し、照射箇所の温度を、例えば、室温~６００℃、好ましくは、３００℃~４００℃まで上昇させてもよい。その結果、赤外線レーザ光Ｌの照射による照射箇所の昇温幅を小さくすることができるため、赤外線レーザ光Ｌの照射による昇温の制御性を向上させることができ、照射箇所の昇温制御を緻密に行うことができる。なお、カーボンナノチューブ４０の形成の停止は赤外線レーザ光Ｌの照射を停止して触媒金属微粒子４４を急冷させることによって行われるが、赤外線レーザ光Ｌの照射の停止による触媒金属微粒子４４の冷却時間は、５秒以内、好ましくは、３秒以内である。 Also when the carbon nanotube 40 is formed, the amount of thermal energy applied to the irradiated portion is adjusted. Specifically, by irradiating the infrared laser beam L with an output of 100 to 10000 W, the temperature of the irradiated portion is raised to 300 to 900 ° C., preferably 400 to 600 ° C. By maintaining the irradiation on the irradiated portion for several minutes, for example, 1 to 60 minutes, the thermal decomposition of the C 2 H 4 gas into carbon atoms is continued, and the supply of carbon atoms is continued. Continue to grow. Further, when the carbon nanotube 40 is formed, the inside of the chamber 11 may be heated with a heater, and the temperature of the irradiated portion may be raised to, for example, room temperature to 600 ° C., preferably 300 ° C. to 400 ° C. As a result, it is possible to reduce the temperature rise width of the irradiated part by the irradiation with the infrared laser beam L, so that the controllability of the temperature rise by the irradiation with the infrared laser beam L can be improved, and the temperature rise control at the irradiation part It can be done precisely. The formation of the carbon nanotubes 40 is stopped by stopping the irradiation of the infrared laser light L and quenching the catalytic metal fine particles 44. The cooling time of the catalytic metal fine particles 44 due to the stop of the irradiation of the infrared laser light L is as follows. Within 5 seconds, preferably within 3 seconds.
　チャンバ１１の内部の圧力は、カーボンナノチューブの十分な成長速度を維持する観点から、例えば、１３~１３３３Ｐａ（０．１~１０Ｔｏｒｒ）とすることが好ましく、６６Ｐａ~６６７Ｐａがより好ましい。 The pressure inside the chamber 11 is preferably 13 to 1333 Pa (0.1 to 10 Torr), and more preferably 66 Pa to 667 Pa, from the viewpoint of maintaining a sufficient growth rate of the carbon nanotubes.
　混合ガス中のＣ２Ｈ４ガスの流量は、効率的にカーボンナノチューブ４５を成長させる観点から、例えば、１~１００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、５~５０ｍＬ／分（ｓｃｃｍ）がより好ましい。 From the viewpoint of efficiently growing the carbon nanotube 45, the flow rate of the C 2 H 4 gas in the mixed gas is preferably 1 to 100 mL / min (sccm), for example, and 5 to 50 mL / min (sccm). More preferred.
　また、混合ガス中の炭素含有ガスとしては、Ｃ２Ｈ４ガスに限らず、ＣＨ４、Ｃ２Ｈ６、Ｃ３Ｈ８、Ｃ３Ｈ６、Ｃ２Ｈ２等の炭化水素ガスや、ＣＨ３ＯＨ、Ｃ２Ｈ５ＯＨ等の炭素含有ガスを代わりに用いることができる。また、Ａｒガスに代えて、他の希ガス、例えば、Ｈｅ、Ｎｅ、Ｋｒ、Ｘｅの各ガスやＮ２ガスを用いることもできる。特に、不活性ガスとして、ＡｒガスだけでなくＮ２ガスをチャンバ１１の内部に導入することにより、カーボンナノチューブ４５の成長速度を速め、かつ品質を向上させることができる。但し、不活性ガスの使用は必須ではない。 Further, the carbon-containing gas in the mixed gas is not limited to C 2 H 4 gas, but may be hydrocarbon gas such as CH 4 , C 2 H 6 , C 3 H 8 , C 3 H 6 , C 2 H 2 , Carbon-containing gases such as CH 3 OH, C 2 H 5 OH can be used instead. Further, instead of Ar gas, other rare gases, for example, He, Ne, Kr, Xe gases or N 2 gas may be used. In particular, by introducing not only Ar gas but also N 2 gas into the chamber 11 as an inert gas, the growth rate of the carbon nanotube 45 can be increased and the quality can be improved. However, the use of an inert gas is not essential.
　不活性ガスとして、Ａｒガスを導入する場合、その流量は、効率的にカーボンナノチューブ４５を成長させる観点から、例えば、１００~２０００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、３００~１０００ｍＬ／分（ｓｃｃｍ）がより好ましい。また、Ｎ２ガスを導入する場合、その流量は、効率的にカーボンナノチューブ４５を成長させる観点から、例えば、１００~１０００ｍＬ／分（ｓｃｃｍ）とすることが好ましく、１００~３００ｍＬ／分（ｓｃｃｍ）がより好ましい。 In the case of introducing Ar gas as the inert gas, the flow rate is preferably 100 to 2000 mL / min (sccm), for example, from the viewpoint of efficiently growing the carbon nanotubes 45, and is preferably 300 to 1000 mL / min ( sccm) is more preferred. In addition, when N 2 gas is introduced, the flow rate is preferably 100 to 1000 mL / min (sccm), for example, from the viewpoint of efficiently growing the carbon nanotube 45, and is preferably 100 to 300 mL / min (sccm). Is more preferable.
　さらに、混合ガスは、炭素含有ガスや不活性ガスに加えて水素含有ガス、例えば、Ｈ２ガスやＮＨ３ガスを含んでいてもよい。水素含有ガスを含む場合、赤外線レーザ光Ｌによる加熱によって水素含有ガスから生じる水素原子は触媒金属微粒子４４の表面を還元し、触媒金属微粒子４４の活性化を行う。これにより、触媒金属微粒子４４を核とするカーボンナノチューブ４５の成長を促進することができる。 Furthermore, the mixed gas may contain a hydrogen-containing gas such as H 2 gas or NH 3 gas in addition to the carbon-containing gas or the inert gas. When a hydrogen-containing gas is contained, hydrogen atoms generated from the hydrogen-containing gas by heating with the infrared laser beam L reduce the surface of the catalyst metal fine particles 44 and activate the catalyst metal fine particles 44. Thereby, the growth of the carbon nanotube 45 having the catalyst metal fine particles 44 as a nucleus can be promoted.
　また、混合ガスには、例えば、Ｏ２、Ｏ３、Ｈ２Ｏ、Ｎ２Ｏ等の酸化ガスを加えてもよい。この場合、カーボンナノチューブ４５の品質を向上させることができる。 Further, the mixed gas, for example, O 2, O 3, H 2 O, may be added to oxidizing gases such as N 2 O. In this case, the quality of the carbon nanotube 45 can be improved.
　カーボンナノチューブ４５は触媒金属微粒子４４の性状を保ったまま成長するため、上述した赤外線レーザ光Ｌの照射及び照射の停止の繰り返しを利用して広範囲において微細であって均一な大きさの触媒金属微粒子４４を生成し、ウエハＷにおいて高密度な触媒金属微粒子４４の分布を実現することにより、高密度のカーボンナノチューブ４５を得ることができる。 Since the carbon nanotube 45 grows while maintaining the properties of the catalytic metal fine particles 44, the catalytic metal fine particles having a fine and uniform size in a wide range by using the above-described irradiation of the infrared laser beam L and the repetition of the stop of the irradiation. High density carbon nanotubes 45 can be obtained by generating 44 and realizing the distribution of the high density catalyst metal fine particles 44 on the wafer W.
　上述したカーボンナノチューブ４５の成長は赤外線レーザ光Ｌが照射される照射箇所及びその近傍のみで実現されるため、本実施の形態では、一の照射箇所においてカーボンナノチューブ４５を成長させた後、レーザ光照射部１３及びガス供給部１４を赤外線レーザ光Ｌのスポット径分だけウエハＷの表面と平行（図７の（Ｃ）中の黒矢印方向）に移動させて他の照射箇所でもカーボンナノチューブ４５を成長させる。すなわち、赤外線レーザ光Ｌによって微細な触媒金属微粒子４４が高密度に形成されたウエハＷの表面を走査するので、ウエハＷの表面の広範囲において微細なカーボンナノチューブ４５を成長させることができる。特に、赤外線レーザ光Ｌの出力、照射時間を均一にすることによって各照射箇所へ付与する熱エネルギーの量を均一にすることにより、各照射箇所において供給される炭素原子の量を同じにすることができ、触媒金属層３８の広範囲において均一な長さのカーボンナノチューブ４５を成長させることができる。 Since the growth of the carbon nanotube 45 described above is realized only at the irradiation spot irradiated with the infrared laser beam L and in the vicinity thereof, in this embodiment, after the carbon nanotube 45 is grown at one irradiation spot, the laser beam is grown. The irradiation unit 13 and the gas supply unit 14 are moved in parallel with the surface of the wafer W by the spot diameter of the infrared laser light L (in the direction of the black arrow in FIG. 7C), so that the carbon nanotubes 45 are moved at other irradiation points. Grow. That is, since the surface of the wafer W on which fine catalyst metal fine particles 44 are formed with high density is scanned by the infrared laser beam L, the fine carbon nanotubes 45 can be grown over a wide range of the surface of the wafer W. In particular, by making the output of the infrared laser beam L and the irradiation time uniform, the amount of heat energy applied to each irradiation point is made uniform, thereby making the amount of carbon atoms supplied at each irradiation point the same. The carbon nanotubes 45 having a uniform length can be grown in a wide range of the catalytic metal layer 38.
　以上、図７のカーボンナノチューブの成長方法によれば、触媒金属層３８へ赤外線レーザ光Ｌが照射されて触媒金属層３８が加熱されるが、赤外線レーザ光Ｌは出力、照射時間を正確に調整することができるので、触媒金属層３８へ付与する熱エネルギーの量を正確に制御することができ、もって、触媒金属の原子の凝集の程度を正確に制御することができる。また、触媒金属層３８への赤外線レーザ光Ｌの照射が停止されて触媒金属層３８が冷却されるが、赤外線レーザ光Ｌの照射の停止によって触媒金属層３８への熱エネルギーの付与を直ちに停止することができ、もって、適切な程度まで進行した凝集を維持したまま、触媒金属を凝固させることができる。その結果、触媒金属層３８から微細な触媒金属微粒子４４を形成することができ、もって、高密度のカーボンナノチューブ４５を得ることができる。 As described above, according to the carbon nanotube growth method of FIG. 7, the catalytic metal layer 38 is irradiated with the infrared laser light L to heat the catalytic metal layer 38. The infrared laser light L accurately adjusts the output and irradiation time. Therefore, the amount of thermal energy applied to the catalyst metal layer 38 can be accurately controlled, and the degree of aggregation of the catalyst metal atoms can be accurately controlled. Further, the irradiation of the infrared laser light L to the catalytic metal layer 38 is stopped and the catalytic metal layer 38 is cooled, but the application of thermal energy to the catalytic metal layer 38 is immediately stopped by the stop of the irradiation of the infrared laser light L. Therefore, the catalytic metal can be solidified while maintaining the agglomeration that has progressed to an appropriate degree. As a result, fine catalyst metal fine particles 44 can be formed from the catalyst metal layer 38, and thus high-density carbon nanotubes 45 can be obtained.
　上述した図７のカーボンナノチューブの成長方法では、触媒金属微粒子４４の形成及びカーボンナノチューブ４５の成長のいずれも赤外線レーザ光Ｌの照射によって行うことができるため、触媒金属微粒子４４の形成及びカーボンナノチューブ４５の成長を同じレーザ光加熱装置１０で行うことができ、スループットを向上するとともに、設備コストも下げることができる。なお、カーボンナノチューブ４５の成長は、炭素含有ガスをプラズマによって分解して炭素原子を生じさせるプラズマ処理装置を用いてもよい。 In the carbon nanotube growth method of FIG. 7 described above, both the formation of the catalyst metal fine particles 44 and the growth of the carbon nanotubes 45 can be performed by irradiation with the infrared laser light L. Therefore, the formation of the catalyst metal fine particles 44 and the carbon nanotube 45 Thus, the same laser beam heating apparatus 10 can be used to improve the throughput and the equipment cost. The growth of the carbon nanotube 45 may be performed using a plasma processing apparatus that generates carbon atoms by decomposing the carbon-containing gas with plasma.
　また、上述した図７のカーボンナノチューブの成長方法では、プラズマを生じさせないため、カーボンナノチューブ４５にプラズマ中の電子やイオンに因るダメージを与えることがなく、結晶欠陥や不純物の導入を抑制して不純物が少ないカーボンナノチューブ４５を形成することができる。 In the carbon nanotube growth method of FIG. 7 described above, since plasma is not generated, the carbon nanotube 45 is not damaged due to electrons and ions in the plasma, and the introduction of crystal defects and impurities is suppressed. The carbon nanotube 45 with few impurities can be formed.
　以上、本発明について、上述した各実施の形態を用いて説明したが、本発明は上述した各実施の形態に限定されるものではない。 As mentioned above, although this invention was demonstrated using each embodiment mentioned above, this invention is not limited to each embodiment mentioned above.
　本出願は、２０１３年５月２９日に出願された日本出願第２０１３−１１２９２７号及び２０１３年６月６日に出願された日本出願第２０１３−１１９８０２号に基づく優先権を主張するものであり、これらの日本出願に記載された全内容を本出願に援用する。 This application claims priority based on Japanese application No. 2013-112927 filed on May 29, 2013 and Japanese application No. 2013-119822 filed on June 6, 2013, The entire contents described in these Japanese applications are incorporated herein by reference.
Ｌ　赤外線レーザ光
Ｗ　ウエハ
１０　レーザ光加熱装置
１３　レーザ光照射部
１４　ガス供給部
３８　触媒金属層
３９　グラフェン
４０　炭素原子層
４１　炭素含有層
４３　ステップ
４４　触媒金属微粒子
４５　カーボンナノチューブ L Infrared laser beam W Wafer 10 Laser beam heating device 13 Laser beam irradiation unit 14 Gas supply unit 38 Catalyst metal layer 39 Graphene 40 Carbon atom layer 41 Carbon-containing layer 43 Step 44 Catalyst metal fine particles 45 Carbon nanotube

Claims (13)

  1. 　触媒金属層へ向けて少なくとも炭素含有ガスを供給するガス供給ステップと、
    　前記触媒金属層へレーザ光を照射するレーザ光照射ステップと、
    　前記照射されたレーザ光によって前記触媒金属層を加熱する加熱ステップと、
    　前記触媒金属層への前記レーザ光の照射を停止する冷却ステップとを有することを特徴とするグラフェンの生成方法。     A gas supply step of supplying at least a carbon-containing gas toward the catalytic metal layer;
    A laser beam irradiation step of irradiating the catalyst metal layer with a laser beam;
    A heating step of heating the catalytic metal layer by the irradiated laser light;
    And a cooling step of stopping irradiation of the laser light onto the catalytic metal layer.
  2. 　前記レーザ光によって前記炭素含有ガスを分解することを特徴とする請求項１記載のグラフェンの生成方法。 The method for producing graphene according to claim 1, wherein the carbon-containing gas is decomposed by the laser beam.
  3. 　前記加熱ステップでは、前記レーザ光によって前記触媒金属層を走査することを特徴とする請求項１記載のグラフェンの生成方法。 The method for producing graphene according to claim 1, wherein, in the heating step, the catalytic metal layer is scanned with the laser beam.
  4. 　前記加熱ステップでは、前記レーザ光によって前記触媒金属層を走査することなく、前記触媒金属層の所定の箇所へ前記レーザ光を照射することを特徴とする請求項１記載のグラフェンの生成方法。 The graphene generation method according to claim 1, wherein, in the heating step, the laser beam is irradiated to a predetermined portion of the catalyst metal layer without scanning the catalyst metal layer with the laser beam.
  5. 　前記ガス供給ステップ及び前記レーザ光照射ステップを同時に行うことを特徴とする請求項１記載のグラフェンの生成方法。 The method for producing graphene according to claim 1, wherein the gas supply step and the laser beam irradiation step are performed simultaneously.
  6. 　触媒金属層及び厚さが制御された炭素含有層が表面に形成された基板へレーザ光を照射する加熱ステップと、
    　前記触媒金属層への前記レーザ光の照射を停止する冷却ステップとを有することを特徴とするグラフェンの生成方法。     A heating step of irradiating a laser beam onto a substrate on which a catalytic metal layer and a carbon-containing layer having a controlled thickness are formed;
    And a cooling step of stopping irradiation of the laser light onto the catalytic metal layer.
  7. 　前記加熱ステップでは、前記レーザ光によって前記基板の表面を走査することを特徴とする請求項６記載のグラフェンの生成方法。 The method for producing graphene according to claim 6, wherein in the heating step, a surface of the substrate is scanned with the laser beam.
  8. 　前記触媒金属層の上に前記炭素含有層が形成されていることを特徴とする請求項６記載のグラフェンの生成方法。 The method for producing graphene according to claim 6, wherein the carbon-containing layer is formed on the catalytic metal layer.
  9. 　前記炭素含有層の上に前記触媒金属層が形成されていることを特徴とする請求項６記載のグラフェンの生成方法。 The method for producing graphene according to claim 6, wherein the catalytic metal layer is formed on the carbon-containing layer.
  10. 　触媒金属層から触媒金属微粒子を形成する触媒金属微粒子形成ステップを有し、
    　前記触媒金属微粒子形成ステップは、前記触媒金属層へレーザ光を照射するレーザ光照射ステップと、前記触媒金属層への前記レーザ光の照射を停止するレーザ光照射停止ステップと、前記触媒金属微粒子へ向けて炭素含有ガスを供給してカーボンナノチューブを前記触媒金属微粒子から成長させるカーボンナノチューブ成長ステップとを有することを特徴とするカーボンナノチューブの成長方法。     A catalyst metal fine particle forming step of forming catalyst metal fine particles from the catalyst metal layer;
    The catalyst metal fine particle forming step includes a laser light irradiation step of irradiating the catalyst metal layer with laser light, a laser light irradiation stop step of stopping irradiation of the laser light on the catalyst metal layer, and the catalyst metal fine particles. And a carbon nanotube growth step in which a carbon-containing gas is supplied to grow carbon nanotubes from the catalyst metal fine particles.
  11. 　前記レーザ光照射ステップでは、前記レーザ光によって前記触媒金属層を走査することを特徴とする請求項１０記載のカーボンナノチューブの成長方法。 11. The carbon nanotube growth method according to claim 10, wherein in the laser beam irradiation step, the catalyst metal layer is scanned with the laser beam.
  12. 　前記カーボンナノチューブ成長ステップでは、前記炭素含有ガスが供給されている空間を介して前記触媒金属微粒子へ前記レーザ光を照射することを特徴とする請求項１０記載のカーボンナノチューブの成長方法。 11. The carbon nanotube growth method according to claim 10, wherein, in the carbon nanotube growth step, the laser light is irradiated to the catalytic metal fine particles through a space to which the carbon-containing gas is supplied.
  13. 　前記カーボンナノチューブ成長ステップでは、前記レーザ光によって前記触媒金属微粒子が形成された基板の表面を走査することを特徴とする請求項１２記載のカーボンナノチューブの成長方法。 13. The carbon nanotube growth method according to claim 12, wherein in the carbon nanotube growth step, the surface of the substrate on which the catalytic metal fine particles are formed is scanned by the laser beam.
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