WO2021024818A1 - Graphene production method and method for producing optical device - Google Patents

Graphene production method and method for producing optical device Download PDF

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WO2021024818A1
WO2021024818A1 PCT/JP2020/028534 JP2020028534W WO2021024818A1 WO 2021024818 A1 WO2021024818 A1 WO 2021024818A1 JP 2020028534 W JP2020028534 W JP 2020028534W WO 2021024818 A1 WO2021024818 A1 WO 2021024818A1
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graphene
substrate
carbon source
solid carbon
thin film
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French (fr)
Japanese (ja)
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英之 牧
鉄馬 中川
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学校法人慶應義塾
地方独立行政法人神奈川県立産業技術総合研究所
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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors

Definitions

  • the present invention relates to a method for producing graphene and a method for producing an optical device, and more particularly to the direct growth of graphene on a substrate and its application.
  • a blackbody radiation light emitting element is known as a light emitting element using graphene, which is a nanocarbon material (see, for example, Patent Document 1).
  • Blackbody radiation by graphene exhibits a broad emission spectrum that follows Planck's law in the near-infrared and infrared regions including the communication wavelength band.
  • the mechanical peeling method is a simple method in which graphene is mechanically peeled from highly oriented pyrolytic graphite using an adhesive tape and transferred to a desired substrate, but the transfer position and the number of layers of graphene can be controlled. It is difficult and the size is at most 10 microns. In addition, wrinkles and defects occur in graphene during transfer of graphene, which makes it unsuitable for practical use and integration.
  • Non-Patent Document 1 based on the CVD method, graphene is placed on an insulating substrate or a silicon substrate by using a solid carbon source such as amorphous carbon (AC) or a polymer as a carbon source and a metal such as Ni as a catalyst.
  • a solid carbon source such as amorphous carbon (AC) or a polymer as a carbon source and a metal such as Ni as a catalyst.
  • Graphene is easily peeled off from the substrate by the known method of directly growing graphene on an insulating substrate, a silicon substrate, etc. by the CVD method.
  • the metal catalyst and carbon compound (carbide) produced by the heat treatment remains on the entire surface of the substrate.
  • problems such as infrared light emission occurring outside the designed light emitting region and current leakage through a metal catalyst or carbide occur, which affects the performance of the optical device.
  • An object of the present invention is to provide a method for producing graphene and its application capable of directly growing graphene with good adhesion and stability on a substrate used for producing the device. Also provided is a method for producing graphene, which can easily and accurately form a graphene pattern.
  • the graphene preparation method is A first metal film is formed on the substrate used for device fabrication, A thin film of solid carbon source is formed on the first metal film, A second metal film is formed on the thin film of the solid carbon source, The first metal film, the thin film of the solid carbon source, and the laminate in which the second metal film is laminated in this order are heat-treated to grow graphene directly on the substrate.
  • the graphene preparation method is A pattern of a laminated body in which a first metal film, a thin film of a solid carbon source, and a second metal film are laminated in this order is formed on a substrate used for manufacturing a device.
  • the solid carbon source is changed to graphene, and a graphene thin film having the pattern is formed on the substrate.
  • the pattern of the laminated body is formed by the lift-off method.
  • a device is manufactured by forming an electrode electrically connected to the graphene thin film of the pattern on the substrate.
  • Graphene can be grown directly on the substrate used for device fabrication with good adhesion and stability. Graphene grown directly on the substrate is suitable for application to optical devices such as light emitting devices, photodetectors, and light modulators.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A.
  • It is an optical microscope image of graphene produced by the method of 1st Embodiment. It is an optical microscope image of a sample surface for Raman mapping. It is a Raman image of the D band of the sample of FIG. It is a Raman image of the G band of the sample of FIG. It is a Raman image of the 2D band of the sample of FIG. It is a schematic diagram of a light emitting element using graphene grown directly on a substrate.
  • Graphene is a sheet-like substance in which carbon atoms are connected in a hexagonal shape like a mesh, and is a basic element of carbon allotropes such as fullerenes, carbon nanotubes, and graphite.
  • graphene is directly grown at a desired position on the surface of a substrate used for manufacturing a device, such as an insulator, silicon, a compound semiconductor, or an oxide semiconductor, in a desired pattern.
  • a solid carbon source is used as the material for graphene growth. When the solid carbon source is annealed together with the catalyst metal, graphene is produced by the carbon atoms contained in the solid carbon source being dissolved in the catalyst metal and recrystallized.
  • a graphene film according to the pattern can be obtained.
  • a thin metal film is inserted between the substrate and the solid carbon source to enhance the adhesive force between the solid carbon source and the substrate.
  • the lift-off method is used to enhance the solid carbon. Stable formation of source pattern.
  • a pattern 21 of a laminate that is the basis of a target graphene pattern is produced on a silicon substrate 11 covered with an insulating film 12 such as a silicon oxide film.
  • the pattern 21 of the laminate includes a solid carbon source.
  • a thin film of amorphous carbon (aC) is used as the solid carbon source, but other materials containing carbon and capable of forming a thin film such as silicon carbide (SiC) and a polymer material are used. You may use it.
  • a substrate such as germanium, a compound semiconductor, an oxide semiconductor, or an insulator may be used instead of the silicon substrate 11 having the insulating film 12 on the surface.
  • a group III-V compound semiconductor substrate containing Ga, As, In, P, etc., a metal oxide semiconductor substrate containing Zn, Ti, In, Ga, O, etc., SiO 2 , Al 2 O 3 , MgO, Hf 2 O 3, GaN, an insulating substrate such as AlN, may be any substrate that is used in the fabrication of the device.
  • the pattern 21 of the laminate containing the solid carbon source is formed between the thin film 14 of the solid carbon source, the metal catalyst layer 15 formed on the surface of the thin film 14 of the solid carbon source, and the thin film 14 of the solid carbon source and the insulating film 12. It has a thin metal film 13 inserted into the.
  • the feature of the pattern 21 of this laminated body is that a thin metal film 13 is inserted between the thin film 14 of the solid carbon source and the insulating film 12 on the substrate 11.
  • the metal film 13 mainly functions to enhance the adhesion between the thin film 14 of the solid carbon source and the substrate (or the insulating film 12), but may contribute to the growth of graphene.
  • the metal film 13 may be formed of a catalyst metal suitable for the growth of graphene.
  • the graphene of the desired pattern is mainly formed by the reaction of the thin film 14 of the solid carbon source and the metal catalyst layer 15.
  • a specific method for forming the pattern 21 including the solid carbon source will be described later with reference to FIGS. 2A to 2G.
  • the pattern 21 containing the solid carbon source is annealed at a high temperature of 1000 to 1100 ° C. in an inert gas atmosphere for several minutes.
  • This heat treatment may be performed by, for example, RTA (Rapid Thermal Annealing) that heats at a temperature that is accurately controlled for a short time by rapid infrared irradiation.
  • RTA Rapid Thermal Annealing
  • the solid carbon source thin film 14 is patterned so as to exist only at necessary locations on the substrate 11. Therefore, it is possible to avoid a state in which a metal catalyst and a carbon compound (carbide) are formed at an undesired portion on the substrate 11. Further, it is not necessary to process the graphene formed on the entire surface of the substrate 11 by etching or the like in a subsequent process.
  • the metal catalyst layer 15 remaining after the heat treatment is removed.
  • the remaining metal catalyst layer 15 is removed, for example, by acid treatment.
  • a thin film of graphene 17 having a desired pattern and a desired size can be obtained on the substrate 11. This method does not include etching the graphene itself or etching the metal film 13.
  • FIG. 2A to 2G are process diagrams of the pattern 21 including the solid carbon source of FIG. 1A.
  • the desired substrate for device fabrication is prepared.
  • a silicon substrate 11 having an insulating film 12 formed on its surface is used.
  • the substrate 11 is a substrate used for optical interconnects and silicon photonics, the optoelectronic device can be easily integrated by using the pattern of graphene 17 formed directly on the substrate 11.
  • a resist film 22 is formed on the entire surface of the substrate.
  • the resist film 22 may be a positive type or a negative type, but as an example, the positive type resist film 22 is formed to have a uniform thickness by spin coating.
  • FIG. 2C light or electron beam is irradiated to expose the surface of the resist film 22 in a predetermined pattern or electron beam drawing is performed (lithography step).
  • the exposed resist film 22 is developed.
  • the exposed portion is dissolved in a developing solution to form a resist mask 23 having a pattern of openings 24.
  • a thin metal film 13 having a film thickness of 0.1 nm to 100 nm, more preferably a thickness of about 0.1 nm to 50 nm is formed on the entire surface.
  • the thickness of the metal film 13 is such that graphene obtained by heat treatment can be stably held on a substrate for device fabrication, and adhesion can be obtained if there is at least one molecular layer.
  • the metal film 13 becomes thicker than 100 nm, there is a high possibility that a layer of a carbon compound such as metal carbide remains between the graphene and the substrate after the heat treatment.
  • the metal film 13 is 100 nm or less, more preferably 50 nm or less, the carbon sublimated by the heat treatment is dissolved in the metal film 13 to form graphene. In this case, it is unlikely that a layer of carbon compound will remain on the substrate. Even when metal carbide is produced, the particulate metal carbide remains scattered or localized on the substrate.
  • the metal film 13 is formed of any metal material capable of adhering the solid carbon source to the insulating film 12.
  • Ni, Cu, Pt, Fe, Ru, Ir, Ge, Co, Ag, Be, V, An, Ba, Hg, B, Zr, Nb, Ta , Te, Mn, Cr, Mo, Ti, Si, W, Na, K, Ca, Mg, Al, Be and the like can be used.
  • Substances containing these elements in the form of carbides or oxides can be used to bond carbon to the substrate.
  • An appropriate material may be selected according to the number of layers of graphene to be produced, the affinity with carbon, the solid solubility of carbon, and the like. Further, by forming the metal film 13 thinly, it is possible to prevent metal from adhering to the inner wall of the opening 24 of the resist mask 23 and the side surface of the resist mask 23.
  • a thin film 14 of a solid carbon source such as amorphous carbon or a polymer is formed on the metal film 13.
  • the amorphous carbon thin film 14 is formed by vapor deposition, sputtering, or the like.
  • vacuum deposition, spin coating, or the like is used.
  • the metal catalyst layer 15 is formed on the thin film 14 of the solid carbon source.
  • the metal catalyst layer 15 is formed by vapor deposition, sputtering, or the like.
  • the thickness of the metal catalyst layer 15 is, for example, about 20 to 200 nm. Depending on the thickness of graphene to be produced, the film thickness can be set within a range that does not exceed the solid solution limit of carbon.
  • the metal catalyst layer 15 may be made of the same material as the metal film 13 or may be made of a different material.
  • any metal in which carbon dissolves can be used.
  • the resist mask 23 is peeled off by the lift-off method.
  • the metal film 13 deposited on the surface of the resist mask 23, the thin film 14 of the solid carbon source, and the metal catalyst layer 15 are removed together with the resist mask 23.
  • the thin film 14 of the solid carbon source having the desired pattern shape is fixed to the substrate 11 by the metal film 13, and the pattern 21 including the solid carbon source can be stably obtained.
  • the solid carbon source thin film 14 in the target pattern region is also the substrate. It separates from 11 and makes it impossible to grow graphene on the substrate 11.
  • the method of the embodiment can stably form the pattern of the solid carbon source on the substrate 11 in the size and shape as designed.
  • graphene of the desired pattern can be formed directly on the substrate 11 without using a transfer method.
  • FIG. 3 is an optical microscope image of graphene grown on the insulating film 12 covering the silicon substrate 11 using the pattern 21 of the solid carbon source formed by the methods of FIGS. 2A to 2G.
  • Graphene was grown by the process of FIG. 1 using amorphous carbon as the solid carbon source and Ni for the metal film 13 and the metal catalyst layer 15.
  • graphene of various sizes and shapes grows directly on the surface of the substrate.
  • the size and shape of the graphene pattern depends on the resolution of the exposure or electron beam lithography system used to pattern the solid carbon source.
  • graphene of the desired shape can be produced and integrated from the order of tens of nanometers to the order of several centimeters.
  • FIG. 4 is an optical microscope image of the sample surface for Raman mapping.
  • Graphene was grown directly on SiO 2 from a solid carbon source by the procedure of FIG.
  • the graphene pattern has a width of about 10 ⁇ m and a length of about 200 ⁇ m.
  • FIG. 5A is a D-band Raman image of the sample of FIG. 4
  • FIG. 5B is a G-band Raman image of the sample of FIG. 4
  • FIG. 5C is a 2D-band Raman image of the sample of FIG.
  • the D band, G band, and 2D band are bands to which the peak of the Raman scattering spectrum of general graphene belongs.
  • the D band in FIG. 5A is a band derived from the crystal structure of graphene such as crystal disorder and defects. Although it depends on the excitation wavelength, the peak wave number (Raman shift) of 1270 cm -1 ⁇ 1450 cm -1 is observed, indicating that graphene comprises polycrystalline or defective.
  • the G band in Fig. 5B is near 1580 cm-1.
  • the peak of the G band is a peak caused by the in-plane expansion and contraction vibration of the 6-membered ring of the carbon atom, and is used as an index showing the presence of graphene and the number of layers of graphene. The larger the number of layers, the lower the frequency side (the side with the smaller wave number).
  • the 2D band in FIG. 5C is a peak derived from the composition of graphene and represents secondary Raman scattering by two phonons.
  • the peak of the 2D band is also used to identify the presence of graphene and the number of graphene layers.
  • the D band, G band, and 2D band which are Raman peaks characteristic of graphene, are measured at the same position on the two-dimensional plane. From this mapping result, it is confirmed that the pattern of FIG. 4 is a graphene pattern formed directly on the substrate.
  • FIG. 6 is a schematic view of a light emitting element 10 which is an example of the optical device of the embodiment.
  • the light emitting element 10 is manufactured by using a thin film of graphene 17 grown directly on the insulating film 12 covering the substrate 11.
  • Electrodes 31 and electrodes 32 that are electrically connected to the thin film of graphene 17 formed in a predetermined pattern are provided.
  • the electrode 31 and the electrode 32 are formed by forming chromium (Cr) and palladium (Pd) with a thickness of 1 nm to 200 nm in this order, for example, by vapor deposition.
  • Cr is formed at 5 nm and Pd is formed at 145 nm.
  • the electrodes 31 and 32 are wire-bonded to a chip on which the light emitting element 10 is mounted (bonding wires are not shown), and are connected to a power source.
  • a protective film or a cap layer may be formed on the surface of the light emitting element 10. By providing the protective film, it is possible to prevent damage to graphene due to the reaction with oxygen, and the light emitting element 10 can be operated in the atmosphere.
  • the thin film of graphene 17 is formed at a predetermined position on the substrate in an arbitrary shape directly from the solid carbon source, so that the light emitting elements 10 are arranged in an array. Is easy.
  • each pattern of graphene 17 is stably formed from the pattern of the solid carbon source obtained by the lift-off method.
  • An electrode pattern corresponding to each thin film pattern of graphene 17 can be formed at once by using a metal mask for vapor deposition. Since this method does not require transfer of graphene or the like, the process is simple and the number of processes can be reduced.
  • FIG. 7 is an optical microscope image of a light emitting device using graphene grown directly from a solid carbon source.
  • the horizontally long shadow seen through the electrodes is the pattern of graphene 17 on the substrate.
  • the width of the pattern of the graphene 17 is 10 ⁇ m
  • the distance between the pair of electrodes arranged so as to overlap the graphene 17 is 10 ⁇ m
  • a light emitting surface of 10 ⁇ m ⁇ 10 ⁇ m is formed on the substrate.
  • FIG. 8 is an infrared camera image showing infrared emission of the graphene light emitting device of FIG. 7.
  • a voltage is applied between the electrodes of the light emitting element, a current flows into the graphene 17, heat radiation due to Joule heat occurs, and light is emitted.
  • a voltage of 17 V was applied, and the observation was carried out for 5 seconds. It can be seen that in the graphene pattern formed directly on the substrate, the region sandwiched between the pair of electrodes emits bright light.
  • graphene with high mobility is used as a channel material in applications to electronic devices such as transistors and sensors.
  • High-quality graphene is required to produce high-speed, low-power-consumption electronic devices, and it is desirable that there is no D-band peak due to polycrystalline properties. That said, the direct growth of graphene of the embodiment is not hindered by its application to electronic devices, and graphite or the like may be formed using graphite formed directly on the substrate in a desired pattern.
  • Graphene absorbs infrared light in a wide wavelength range.
  • An infrared sensor can be configured by arranging photodetection elements using graphene as a light absorption layer in an array and applying a bias to each of the elements to draw out carriers generated by light absorption.
  • Graphene also a small heat capacity of nanomaterials specific, the large deviation of heat to the substrate, 10 7 times or more as compared with conventional incandescent bulbs high speed, it is possible to modulate the following relaxation time 100 ps. That is, by switching the voltage applied to graphene on / off, high-speed modulation of emission intensity is realized.
  • the graphene produced on the device substrate in the embodiment can also be used as a minute heat source.
  • Optical modulators and optical switches can be manufactured by combining graphene as a heat source such as a heater and combining thermo-optical effects.
  • the graphene growth technique of the embodiment can easily integrate optical devices such as a light emitting element, a light receiving element, and an optical modulator, and is suitable for application in the field of optical communication.
  • the graphene growth technique of the embodiment may be applied not only to optical devices but also to electronic devices.
  • a large area of graphene is formed on an arbitrary substrate.
  • the method for producing stable graphene with high adhesion can also be applied to the production of unpatterned large-area graphene.
  • FIGS. 9A-9D are process diagrams for producing graphene according to the second embodiment.
  • graphene is directly grown on the surface of a substrate used for device fabrication, such as an insulator, silicon, germanium, a compound semiconductor, and an oxide semiconductor.
  • a substrate used for device fabrication such as an insulator, silicon, germanium, a compound semiconductor, and an oxide semiconductor.
  • no transfer of graphene for device fabrication is required.
  • a thin metal film 43, a thin film 44 of a solid carbon source, and a metal catalyst layer 45 are formed in this order on the entire surface of a substrate 41 covered with an insulating film 42 such as a silicon oxide film.
  • an insulating film 42 such as a silicon oxide film.
  • a thin film of amorphous carbon (aC) is used as the solid carbon source, but other materials containing carbon and capable of forming a thin film such as silicon carbide (SiC) and a polymer material are used. You may use it.
  • the substrate 41 any substrate that can be used for manufacturing the device may be used.
  • the metal film 13 mainly functions to enhance the adhesion between the thin film 44 of the solid carbon source and the substrate 41 (or the insulating film 42), but may contribute to the growth of graphene.
  • the metal film 43 may be formed of a catalyst metal suitable for the growth of graphene.
  • the entire substrate having the metal film 43, the thin film 44 of the solid carbon source, and the metal catalyst layer 45 laminated is annealed at a high temperature of 1000 to 1100 ° C. for several minutes in an inert gas atmosphere.
  • the carbon sublimated from the solid carbon source is solid-solved in the metal catalyst layer 45, and is partially dissolved in the metal film 43 to form graphene.
  • FIG. 9C the metal catalyst layer 45 remaining on the surface of graphene 47 is removed.
  • the remaining metal catalyst layer 15 is removed by acid treatment or the like.
  • FIG. 9D graphene 47 can be obtained on the entire surface of the substrate 41.
  • the graphene 47 having a large area is closely held to the substrate 41 (or the insulating film 42), and is not easily peeled off even if it is subjected to processing such as etching in the subsequent steps.
  • FIG. 10 is an optical microscopic image of large-area graphene produced by the method of FIG.
  • a 5 nm thick Ni film is deposited on a silicon substrate by thin film deposition, a 5 nm thick amorphous carbon thin film is formed by thin film deposition, a 20 nm thick Ni film is formed by thin film deposition, and annealing is performed in an argon atmosphere. Is going.
  • a graphene film is stably formed on the entire surface of the silicon substrate.
  • the adhesive force between the carbon solid source and the substrate can be strengthened.
  • the subsequent lift-off treatment when the solid carbon source and the metal catalyst layer in the unnecessary portion are removed, it is possible to prevent the solid carbon source forming the desired pattern from separating from the substrate surface.
  • (2) Not only can a large-area graphene film covering the entire substrate be stably formed, but also a thin film of graphene can be directly formed at an arbitrary position on the substrate with an arbitrary size and an arbitrary pattern designed in advance. Can be done. No steps such as etching of the catalyst metal, etching of graphene, and transfer of graphene are required.
  • (4) Optical devices made using graphene formed directly at desired positions on the substrate are suitable for arraying and integration.

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Abstract

A first metal film is formed on a substrate used in device production; a thin film of a solid carbon source is formed on the first metal film; a second metal film is formed on the thin film of a solid carbon source; and a laminate in which the first metal film, the thin film of a solid carbon source, and the second metal film are stacked in the stated order is subjected to heat treatment to grow graphene directly on the substrate.

Description

グラフェン作製方法、及び光デバイスの作製方法Graphene fabrication method and optical device fabrication method
　本発明は、グラフェン作製方法、及び光デバイスの作製方法に関し、特に、基板上へのグラフェンの直接成長とその応用に関する。 The present invention relates to a method for producing graphene and a method for producing an optical device, and more particularly to the direct growth of graphene on a substrate and its application.
　ナノカーボン材料であるグラフェンを用いた発光素子として、黒体放射発光素子が知られている（たとえば、特許文献１参照）。グラフェンによる黒体放射は、通信波長帯を含む近赤外、及び赤外領域でプランク則に従うブロードな発光スペクトルを示す。 A blackbody radiation light emitting element is known as a light emitting element using graphene, which is a nanocarbon material (see, for example, Patent Document 1). Blackbody radiation by graphene exhibits a broad emission spectrum that follows Planck's law in the near-infrared and infrared regions including the communication wavelength band.
　一般にグラフェンは、シリコン、絶縁体等のデバイス作製用の基板に直接成長するのが難しく、化学気相成長法（ＣＶＤ：Chemical Vapor Deposition）等によって単結晶金属上に成長した後に、機械的剥離でデバイス作製用の基板に転写している。 In general, it is difficult for graphene to grow directly on a substrate for device fabrication such as silicon and insulators, and after growing on a single crystal metal by chemical vapor deposition (CVD), etc., it is mechanically peeled off. Transferred to a substrate for device fabrication.
　機械的剥離法は、粘着テープを用いて、高配向熱分解黒鉛からグラフェンを機械的に剥離し、所望の基板に転写するという簡便な手法であるが、グラフェンの転写位置や層数の制御が難しく、大きさも高々十ミクロン程度である。また、グラフェンの転写時にグラフェンにシワや欠陥が生じ、実用化、集積化には不向きである。 The mechanical peeling method is a simple method in which graphene is mechanically peeled from highly oriented pyrolytic graphite using an adhesive tape and transferred to a desired substrate, but the transfer position and the number of layers of graphene can be controlled. It is difficult and the size is at most 10 microns. In addition, wrinkles and defects occur in graphene during transfer of graphene, which makes it unsuitable for practical use and integration.
　近年、ＣＶＤ法をもとに、炭素源としてアモルファスカーボン（ａ－Ｃ）やポリマー等の固体炭素源を用い、触媒としてＮｉ等の金属を用いて、グラフェンを絶縁性基板やシリコン基板の上に直接成長する方法が報告されている（たとえば、非特許文献１及び非特許文献２参照）。 In recent years, based on the CVD method, graphene is placed on an insulating substrate or a silicon substrate by using a solid carbon source such as amorphous carbon (AC) or a polymer as a carbon source and a metal such as Ni as a catalyst. Methods of direct growth have been reported (see, for example, Non-Patent Document 1 and Non-Patent Document 2).
特許第６１５５０１２号Patent No. 6155012
　ＣＶＤ法により絶縁基板、シリコン基板などにグラフェンを直接成長する公知の手法では、グラフェンが基板からはがれやすい。特に、デバイスに加工する際にグラフェンが剥離して損傷しやすく、所望のデバイス構成が得られないという問題がある。また、ほとんどの場合、熱処理で生成される金属触媒と炭素の化合物（カーバイド）が、基板の表面全体に残留する。発光素子の場合は、設計された発光領域の外でも赤外発光が生じる、金属触媒やカーバイドを通じて電流がリークするなどの問題が生じ、光デバイス性能に影響する。 Graphene is easily peeled off from the substrate by the known method of directly growing graphene on an insulating substrate, a silicon substrate, etc. by the CVD method. In particular, there is a problem that graphene is easily peeled off and damaged during processing into a device, and a desired device configuration cannot be obtained. In most cases, the metal catalyst and carbon compound (carbide) produced by the heat treatment remains on the entire surface of the substrate. In the case of a light emitting element, problems such as infrared light emission occurring outside the designed light emitting region and current leakage through a metal catalyst or carbide occur, which affects the performance of the optical device.
　本発明は、デバイスの作製に利用される基板上に、密着性良く安定してグラフェンを直接成長することができるグラフェンの作製方法とその応用を提供することを目的とする。また、容易かつ正確にグラフェンのパターンを形成することのできるグラフェンの作製法を提供する。 An object of the present invention is to provide a method for producing graphene and its application capable of directly growing graphene with good adhesion and stability on a substrate used for producing the device. Also provided is a method for producing graphene, which can easily and accurately form a graphene pattern.
　本発明の第１の態様において、グラフェン作製方法は、
　デバイス作製に用いる基板の上に第１の金属膜を形成し、
　前記第１の金属膜の上に固体炭素源の薄膜を形成し、
　前記固体炭素源の薄膜の上に第２の金属膜を形成し、
　前記第１の金属膜、前記固体炭素源の薄膜、及び前記第２の金属膜がこの順で重ねられた積層体に熱処理を施して、前記基板の上にグラフェンを直接成長する。 In the first aspect of the present invention, the graphene preparation method is
A first metal film is formed on the substrate used for device fabrication,
A thin film of solid carbon source is formed on the first metal film,
A second metal film is formed on the thin film of the solid carbon source,
The first metal film, the thin film of the solid carbon source, and the laminate in which the second metal film is laminated in this order are heat-treated to grow graphene directly on the substrate.
　本発明の第２の態様において、グラフェン作製方法は、
　デバイス作製に用いる基板の上に、第１の金属膜、固体炭素源の薄膜、及び第２の金属膜がこの順で重ねられた積層体のパターンを形成し、
　前記積層体を熱処理することで前記固体炭素源をグラフェンに変えて、前記基板の上に前記パターンのグラフェン薄膜を形成する。 In the second aspect of the present invention, the graphene preparation method is
A pattern of a laminated body in which a first metal film, a thin film of a solid carbon source, and a second metal film are laminated in this order is formed on a substrate used for manufacturing a device.
By heat-treating the laminate, the solid carbon source is changed to graphene, and a graphene thin film having the pattern is formed on the substrate.
　好ましくは、前記積層体のパターンはリフトオフ法で形成される。 Preferably, the pattern of the laminated body is formed by the lift-off method.
　前記基板の上に、前記パターンのグラフェン薄膜と電気的に接続される電極を形成してデバイスが作製される。 A device is manufactured by forming an electrode electrically connected to the graphene thin film of the pattern on the substrate.
　デバイス作製に用いる基板の上に、密着性良く安定してグラフェンを直接成長することができる。基板上に直接成長されたグラフェンは、発光素子、光検出器、光変調器などの光デバイスへの応用に好適である。 Graphene can be grown directly on the substrate used for device fabrication with good adhesion and stability. Graphene grown directly on the substrate is suitable for application to optical devices such as light emitting devices, photodetectors, and light modulators.
第１実施形態のグラフェン生成の基本工程図である。It is a basic process diagram of graphene production of 1st Embodiment. 第１実施形態のグラフェン生成の基本工程図である。It is a basic process diagram of graphene production of 1st Embodiment. 第１実施形態のグラフェン生成の基本工程図である。It is a basic process diagram of graphene production of 1st Embodiment. 第１実施形態のグラフェン生成の基本工程図である。It is a basic process diagram of graphene production of 1st Embodiment. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 図１Ａの固体炭素源を含むパターンの形成工程図である。FIG. 3 is a process diagram of forming a pattern including the solid carbon source of FIG. 1A. 第１実施形態の方法で作製したグラフェンの光学顕微鏡像である。It is an optical microscope image of graphene produced by the method of 1st Embodiment. ラマンマッピングのためのサンプル表面の光学顕微鏡像である。It is an optical microscope image of a sample surface for Raman mapping. 図４のサンプルのＤバンドのラマン画像である。It is a Raman image of the D band of the sample of FIG. 図４のサンプルのＧバンドのラマン画像である。It is a Raman image of the G band of the sample of FIG. 図４のサンプルの２Ｄバンドのラマン画像である。It is a Raman image of the 2D band of the sample of FIG. 基板上に直接成長したグラフェンを用いた発光素子の模式図である。It is a schematic diagram of a light emitting element using graphene grown directly on a substrate. 炭素固体源から基板へ直接成長したグラフェンの発光素子の光学顕微鏡像である。It is an optical microscope image of a light emitting element of graphene grown directly from a carbon solid source to a substrate. 図７のグラフェンの発光素子の赤外発光を示す赤外カメラ像である。It is an infrared camera image which shows the infrared emission of the light emitting element of graphene of FIG. 第２実施形態のグラフェンの作製工程図である。It is a manufacturing process drawing of graphene of 2nd Embodiment. 第２実施形態のグラフェンの作製工程図である。It is a manufacturing process drawing of graphene of 2nd Embodiment. 第２実施形態のグラフェンの作製工程図である。It is a manufacturing process drawing of graphene of 2nd Embodiment. 第２実施形態のグラフェンの作製工程図である。It is a manufacturing process drawing of graphene of 2nd Embodiment. 第２実施形態の方法で作製したグラフェンの光学顕微鏡像である。It is an optical microscope image of graphene produced by the method of 2nd Embodiment.
　＜第１実施形態＞
　図１Ａ～図１Ｄは、第１実施形態のグラフェンの作製工程図である。グラフェンは、炭素原子が網目のように六角形に結びついたシート状の物質であり、フラーレン、カーボンナノチューブ、グラファイトなどの炭素同素体の基本要素である。 <First Embodiment>
1A to 1D are process diagrams for producing graphene according to the first embodiment. Graphene is a sheet-like substance in which carbon atoms are connected in a hexagonal shape like a mesh, and is a basic element of carbon allotropes such as fullerenes, carbon nanotubes, and graphite.
　第１実施形態では、絶縁体、シリコン、化合物半導体、酸化物半導体等、デバイスの作製に用いられる基板の表面の所望の位置に、所望のパターンで、グラフェンを直接成長する。グラフェン成長の材料として、固体炭素源を用いる。固体炭素源を触媒金属と共にアニールすると、固体炭素源に含まれる炭素原子が触媒金属に固溶、再結晶化することで、グラフェンが生成される。 In the first embodiment, graphene is directly grown at a desired position on the surface of a substrate used for manufacturing a device, such as an insulator, silicon, a compound semiconductor, or an oxide semiconductor, in a desired pattern. A solid carbon source is used as the material for graphene growth. When the solid carbon source is annealed together with the catalyst metal, graphene is produced by the carbon atoms contained in the solid carbon source being dissolved in the catalyst metal and recrystallized.
　このとき、あらかじめ固体炭素源を所定のパターンに形成しておくことで、そのパターンどおりのグラフェン膜を得ることができる。固体炭素源のパターンを作製する際に、基板と固体炭素源の間に、薄い金属膜を挿入することで、固体炭素源と基板との付着力を増強し、たとえば、リフトオフ法によって、固体炭素源のパターンを安定的に形成する。固体炭素源のパターン形成の詳細を説明する前に、グラフェン生成の基本プロセスを説明する。 At this time, by forming the solid carbon source in a predetermined pattern in advance, a graphene film according to the pattern can be obtained. When making a pattern of a solid carbon source, a thin metal film is inserted between the substrate and the solid carbon source to enhance the adhesive force between the solid carbon source and the substrate. For example, the lift-off method is used to enhance the solid carbon. Stable formation of source pattern. Before explaining the details of patterning of solid carbon sources, the basic process of graphene formation will be described.
　図１Ａで、シリコン酸化膜等の絶縁膜１２で覆われたシリコンの基板１１の上に、目的とするグラフェンパターンの基礎となる積層体のパターン２１を作製する。積層体のパターン２１は、固体炭素源を含む。以下で説明する実施形態では、固体炭素源としてアモルファスカーボン（ａ-Ｃ）の薄膜を用いるが、炭化ケイ素（ＳｉＣ）、ポリマー材料など、炭素を含有し、かつ薄膜形成が可能なその他の材料を用いてもよい。また、表面に絶縁膜１２を有するシリコンの基板１１に替えて、ゲルマニウム、化合物半導体、酸化物半導体、絶縁体などの基板を用いてもよい。 In FIG. 1A, a pattern 21 of a laminate that is the basis of a target graphene pattern is produced on a silicon substrate 11 covered with an insulating film 12 such as a silicon oxide film. The pattern 21 of the laminate includes a solid carbon source. In the embodiments described below, a thin film of amorphous carbon (aC) is used as the solid carbon source, but other materials containing carbon and capable of forming a thin film such as silicon carbide (SiC) and a polymer material are used. You may use it. Further, instead of the silicon substrate 11 having the insulating film 12 on the surface, a substrate such as germanium, a compound semiconductor, an oxide semiconductor, or an insulator may be used.
　例えば、Ｇａ，Ａｓ，Ｉｎ，Ｐ等を含むIII-V族化合物半導体基板、Ｚｎ，Ｔｉ，Ｉｎ，Ｇａ，Ｏ等を含む金属酸化物半導体基板、ＳｉＯ2，Ａｌ2Ｏ3，ＭｇＯ，Ｈｆ2Ｏ3，ＧａＮ，ＡｌＮなどの絶縁基板など、デバイスの作製に利用される任意の基板を用いることができる。 For example, a group III-V compound semiconductor substrate containing Ga, As, In, P, etc., a metal oxide semiconductor substrate containing Zn, Ti, In, Ga, O, etc., SiO 2 , Al 2 O 3 , MgO, Hf 2 O 3, GaN, an insulating substrate such as AlN, may be any substrate that is used in the fabrication of the device.
　固体炭素源を含む積層体のパターン２１は、固体炭素源の薄膜１４と、固体炭素源の薄膜１４の表面に形成された金属触媒層１５と、固体炭素源の薄膜１４と絶縁膜１２の間に挿入された薄い金属膜１３とを有する。 The pattern 21 of the laminate containing the solid carbon source is formed between the thin film 14 of the solid carbon source, the metal catalyst layer 15 formed on the surface of the thin film 14 of the solid carbon source, and the thin film 14 of the solid carbon source and the insulating film 12. It has a thin metal film 13 inserted into the.
　この積層体のパターン２１の特徴は、固体炭素源の薄膜１４と基板１１上の絶縁膜１２の間に、薄い金属膜１３が挿入されていることである。金属膜１３は、主として固体炭素源の薄膜１４と基板（または絶縁膜１２）との間の密着性を高める働きをするが、グラフェンの成長に寄与させてもよい。その場合は、グラフェンの成長に適した触媒金属で金属膜１３を形成してもよい。 The feature of the pattern 21 of this laminated body is that a thin metal film 13 is inserted between the thin film 14 of the solid carbon source and the insulating film 12 on the substrate 11. The metal film 13 mainly functions to enhance the adhesion between the thin film 14 of the solid carbon source and the substrate (or the insulating film 12), but may contribute to the growth of graphene. In that case, the metal film 13 may be formed of a catalyst metal suitable for the growth of graphene.
　所望のパターンのグラフェンは、主として固体炭素源の薄膜１４と金属触媒層１５の反応によって形成される。固体炭素源を含むパターン２１の具体的な形成方法は、図２Ａ～図２Ｇを参照して後述する。 The graphene of the desired pattern is mainly formed by the reaction of the thin film 14 of the solid carbon source and the metal catalyst layer 15. A specific method for forming the pattern 21 including the solid carbon source will be described later with reference to FIGS. 2A to 2G.
　図１Ｂで、固体炭素源を含むパターン２１を、１０００～１１００℃の高温で、不活性ガス雰囲気下で数分間、アニールする。この熱処理は、たとえば、急速の赤外線照射により、短時間、かつ正確に制御された温度で加熱を行うＲＴＡ（Rapid Thermal Annealing）により行ってもよい。ＲＴＡにより、固体炭素源の薄膜１４はグラフェン１７に変化する。 In FIG. 1B, the pattern 21 containing the solid carbon source is annealed at a high temperature of 1000 to 1100 ° C. in an inert gas atmosphere for several minutes. This heat treatment may be performed by, for example, RTA (Rapid Thermal Annealing) that heats at a temperature that is accurately controlled for a short time by rapid infrared irradiation. The RTA transforms the solid carbon source thin film 14 into graphene 17.
　ＲＴＡに先立つ図１Ａの段階で、固体炭素源の薄膜１４は、基板１１上の必要な箇所にだけ存在するようにパターニングされている。したがって、基板１１上の望ましくない箇所に金属触媒と炭素の化合物（カーバイド）が形成される状態を回避できる。また、基板１１の全面に形成されたグラフェンを後工程でエッチング等により加工する必要がない。 At the stage of FIG. 1A prior to RTA, the solid carbon source thin film 14 is patterned so as to exist only at necessary locations on the substrate 11. Therefore, it is possible to avoid a state in which a metal catalyst and a carbon compound (carbide) are formed at an undesired portion on the substrate 11. Further, it is not necessary to process the graphene formed on the entire surface of the substrate 11 by etching or the like in a subsequent process.
　図１Ｃで、熱処理後に残留した金属触媒層１５を除去する。残存する金属触媒層１５は、たとえば、酸処理によって除去される。これにより、図１Ｄで、基板１１上に、所望のパターン、所望の大きさのグラフェン１７の薄膜を得ることができる。この方法は、グラフェン自体のエッチングや、金属膜１３のエッチングを含まない。 In FIG. 1C, the metal catalyst layer 15 remaining after the heat treatment is removed. The remaining metal catalyst layer 15 is removed, for example, by acid treatment. As a result, in FIG. 1D, a thin film of graphene 17 having a desired pattern and a desired size can be obtained on the substrate 11. This method does not include etching the graphene itself or etching the metal film 13.
　図２Ａ～図２Ｇは、図１Ａの固体炭素源を含むパターン２１の形成工程図である。図２Ａで、デバイス作製のための所望の基板を準備する。この例では、表面に絶縁膜１２が形成されたシリコンの基板１１を用いる。基板１１が、光インターコネクトやシリコンフォトニクスに用いられる基板である場合、基板１１に直接形成されるグラフェン１７のパターンを用いて、光電子デバイスを容易に集積化することができる。 2A to 2G are process diagrams of the pattern 21 including the solid carbon source of FIG. 1A. In FIG. 2A, the desired substrate for device fabrication is prepared. In this example, a silicon substrate 11 having an insulating film 12 formed on its surface is used. When the substrate 11 is a substrate used for optical interconnects and silicon photonics, the optoelectronic device can be easily integrated by using the pattern of graphene 17 formed directly on the substrate 11.
　図２Ｂで、基板の全面にレジスト膜２２を形成する。レジスト膜２２はポジ型でもネガ型でもよいが、一例として、ポジ型のレジスト膜２２を、スピンコーティングにより均一な厚さに形成する。 In FIG. 2B, a resist film 22 is formed on the entire surface of the substrate. The resist film 22 may be a positive type or a negative type, but as an example, the positive type resist film 22 is formed to have a uniform thickness by spin coating.
　図２Ｃで、光または電子線を照射して、レジスト膜２２の表面に所定のパターンで露光または電子線描画を行う（リソグラフィ工程）。 In FIG. 2C, light or electron beam is irradiated to expose the surface of the resist film 22 in a predetermined pattern or electron beam drawing is performed (lithography step).
　図２Ｄで、露光されたレジスト膜２２を現像する。ポジ型レジストを用いた場合、露光された部分が現像液に溶解して、開口２４のパターンを持つレジストマスク２３が形成される。 In FIG. 2D, the exposed resist film 22 is developed. When a positive resist is used, the exposed portion is dissolved in a developing solution to form a resist mask 23 having a pattern of openings 24.
　図２Ｅで、全面に、膜厚が０．１ｎｍ～１００ｎｍ、より好ましくは厚さ０．１ｎｍ～５０ｎｍ程度の薄い金属膜１３を形成する。金属膜１３の厚さは、熱処理により得られるグラフェンを安定してデバイス作製用の基板上に保持できる厚さであり、少なくとも１分子層あれば、密着性が得られる。金属膜１３が１００ｎｍを超えて厚くなると、熱処理後に、グラフェンと基板の間に金属カーバイド等の炭素化合物の層が残る可能性が高い。 In FIG. 2E, a thin metal film 13 having a film thickness of 0.1 nm to 100 nm, more preferably a thickness of about 0.1 nm to 50 nm is formed on the entire surface. The thickness of the metal film 13 is such that graphene obtained by heat treatment can be stably held on a substrate for device fabrication, and adhesion can be obtained if there is at least one molecular layer. When the metal film 13 becomes thicker than 100 nm, there is a high possibility that a layer of a carbon compound such as metal carbide remains between the graphene and the substrate after the heat treatment.
　金属膜１３が１００ｎｍ以下、より好ましくは５０ｎｍ以下であれば、熱処理により昇華した炭素が金属膜１３に固溶してグラフェンを形成する。この場合、基板上に炭素化合物の層が残る蓋然性は低い。金属カーバイドが生成される場合であっても、粒子状の金属カーバイドが基板上に散在または局在するにとどまる。 When the metal film 13 is 100 nm or less, more preferably 50 nm or less, the carbon sublimated by the heat treatment is dissolved in the metal film 13 to form graphene. In this case, it is unlikely that a layer of carbon compound will remain on the substrate. Even when metal carbide is produced, the particulate metal carbide remains scattered or localized on the substrate.
　金属膜１３は固体炭素源を絶縁膜１２に密着することのできる任意の金属材料で形成される。金属膜１３をグラフェン成長の触媒としても利用する場合は、Ｎｉ，Ｃｕ，Ｐｔ，Ｆｅ，Ｒｕ，Ｉｒ，Ｇｅ，Ｃｏ，Ａｇ，Ｂｅ，Ｖ，Ａｎ，Ｂａ，Ｈｇ，Ｂ，Ｚｒ，Ｎｂ，Ｔａ，Ｔｅ，Ｍｎ，Ｃｒ，Ｍｏ，Ｔｉ，Ｓｉ，Ｗ，Ｎａ，Ｋ，Ｃａ，Ｍｇ，Ａｌ，Ｂｅ等を用いることができる。炭化物（カーバイド）や酸化物の状態のあるこれらの元素を含む物質は、カーボンと基板との接着に使用できる。作製したいグラフェンの層数により、炭素との親和性、炭素の固溶度等に応じて、適切な材料を選択すればよい。また、金属膜１３を薄く形成することで、レジストマスク２３の開口２４の内壁や、レジストマスク２３の側面に金属が付着することが抑制される。 The metal film 13 is formed of any metal material capable of adhering the solid carbon source to the insulating film 12. When the metal film 13 is also used as a catalyst for graphene growth, Ni, Cu, Pt, Fe, Ru, Ir, Ge, Co, Ag, Be, V, An, Ba, Hg, B, Zr, Nb, Ta , Te, Mn, Cr, Mo, Ti, Si, W, Na, K, Ca, Mg, Al, Be and the like can be used. Substances containing these elements in the form of carbides or oxides can be used to bond carbon to the substrate. An appropriate material may be selected according to the number of layers of graphene to be produced, the affinity with carbon, the solid solubility of carbon, and the like. Further, by forming the metal film 13 thinly, it is possible to prevent metal from adhering to the inner wall of the opening 24 of the resist mask 23 and the side surface of the resist mask 23.
　図２Ｆで、金属膜１３の上に、アモルファスカーボン、ポリマー等の固体炭素源の薄膜１４を形成する。アモルファスカーボンの薄膜１４は、蒸着、スパッタリング等で形成される。ポリマーの薄膜を形成する場合は、真空蒸着、スピンコート法等を用いる。 In FIG. 2F, a thin film 14 of a solid carbon source such as amorphous carbon or a polymer is formed on the metal film 13. The amorphous carbon thin film 14 is formed by vapor deposition, sputtering, or the like. When forming a polymer thin film, vacuum deposition, spin coating, or the like is used.
　固体炭素源の薄膜１４の上に、金属触媒層１５を形成する。金属触媒層１５は、蒸着、スパッタリング等で形成される。金属触媒層１５の厚さは、一例として２０～２００ｎｍ程度である。作製したいグラフェンの厚さに応じ、炭素の固溶限界を超えない範囲で、膜厚を設定することができる。 The metal catalyst layer 15 is formed on the thin film 14 of the solid carbon source. The metal catalyst layer 15 is formed by vapor deposition, sputtering, or the like. The thickness of the metal catalyst layer 15 is, for example, about 20 to 200 nm. Depending on the thickness of graphene to be produced, the film thickness can be set within a range that does not exceed the solid solution limit of carbon.
　金属触媒層１５は、金属膜１３と同じ材料であってもよいし、異なる材料であってもよい。金属触媒層１５として、カーボンが固溶する任意の金属を用いることができる。たとえば、Ｎｉ，Ｃｕ，Ｐｔ，Ｆｅ，Ｒｕ，Ｉｒ，Ｇｅ，Ｃｏ，Ａｇ，Ｂｅ，Ｖ，Ａｎ，Ｂａ，Ｈｇ，Ｂ，Ｚｒ，Ｎｂ，Ｔａ，Ｔｅ，Ｍｎ、Ｃｒ，Ｍｏ，Ｔｉ，Ｓｉ，Ｗ，Ｎａ，Ｋ，Ｃａ，Ｍｇ，Ａｌ，Ｂｅ等から、目的とするグラフェンの層数により、炭素との親和性、炭素の固溶度に応じて、適切な材料を選択することができる。 The metal catalyst layer 15 may be made of the same material as the metal film 13 or may be made of a different material. As the metal catalyst layer 15, any metal in which carbon dissolves can be used. For example, Ni, Cu, Pt, Fe, Ru, Ir, Ge, Co, Ag, Be, V, An, Ba, Hg, B, Zr, Nb, Ta, Te, Mn, Cr, Mo, Ti, Si, From W, Na, K, Ca, Mg, Al, Be and the like, an appropriate material can be selected according to the number of layers of the target graphene, the affinity with carbon, and the solid solubility of carbon.
　図２Ｇで、リフトオフ法により、レジストマスク２３を剥離する。リフトオフ処理において、レジストマスク２３とともに、レジストマスク２３の表面に堆積された金属膜１３、固体炭素源の薄膜１４、及び金属触媒層１５も除去される。目的とするパターン形状の固体炭素源の薄膜１４は、金属膜１３によって基板１１に固定されており、固体炭素源を含むパターン２１を安定的に得ることができる。 In FIG. 2G, the resist mask 23 is peeled off by the lift-off method. In the lift-off treatment, the metal film 13 deposited on the surface of the resist mask 23, the thin film 14 of the solid carbon source, and the metal catalyst layer 15 are removed together with the resist mask 23. The thin film 14 of the solid carbon source having the desired pattern shape is fixed to the substrate 11 by the metal film 13, and the pattern 21 including the solid carbon source can be stably obtained.
　基板１１上の絶縁膜１２と固体炭素源の薄膜１４の間に薄い金属膜１３がない場合、リフトオフでレジストマスク２３を剥離するときに、目的のパターン領域にある固体炭素源の薄膜１４も基板１１から分離してしまい、基板１１上にグラフェンを成長することができなくなる。 When there is no thin metal film 13 between the insulating film 12 and the solid carbon source thin film 14 on the substrate 11, when the resist mask 23 is peeled off by lift-off, the solid carbon source thin film 14 in the target pattern region is also the substrate. It separates from 11 and makes it impossible to grow graphene on the substrate 11.
　実施形態の手法は、固体炭素源のパターンを、設計どおりの大きさと形状で、基板１１上に安定して形成することができる。基板上であらかじめパターニングされている固体炭素源からグラフェンを成長することで、転写法を用いずに、基板１１上に所望のパターンのグラフェンを直接形成することができる。 The method of the embodiment can stably form the pattern of the solid carbon source on the substrate 11 in the size and shape as designed. By growing graphene from a solid carbon source pre-patterned on the substrate, graphene of the desired pattern can be formed directly on the substrate 11 without using a transfer method.
　図３は、図２Ａ～図２Ｇの方法で形成した固体炭素源のパターン２１を用いて、シリコンの基板１１を覆う絶縁膜１２上に成長したグラフェンの光学顕微鏡像である。固体炭素源としてアモルファスカーボンを用い、金属膜１３と金属触媒層１５にＮｉを用い、図１のプロセスでグラフェンを成長した。 FIG. 3 is an optical microscope image of graphene grown on the insulating film 12 covering the silicon substrate 11 using the pattern 21 of the solid carbon source formed by the methods of FIGS. 2A to 2G. Graphene was grown by the process of FIG. 1 using amorphous carbon as the solid carbon source and Ni for the metal film 13 and the metal catalyst layer 15.
　固体炭素源のパターン２１を用いることで、様々な大きさ、及び形状のグラフェンが、基板の表面に直接成長している。グラフェンパターンの寸法と形状は、固体炭素源のパターン形成に用いられる露光装置または電子線描画装置の分解能に依存する。原理的には、数十ナノメートルのオーダーから、数センチメートルのオーダーまで、所望の形状のグラフェンの作製と集積化が可能になる。 By using the pattern 21 of the solid carbon source, graphene of various sizes and shapes grows directly on the surface of the substrate. The size and shape of the graphene pattern depends on the resolution of the exposure or electron beam lithography system used to pattern the solid carbon source. In principle, graphene of the desired shape can be produced and integrated from the order of tens of nanometers to the order of several centimeters.
　図４は、ラマンマッピングのためのサンプル表面の光学顕微鏡像である。図１の手順により、ＳｉＯ2上に固体炭素源から直接グラフェンを成長した。グラフェンパターンの幅は約１０μｍ、長さは約２００μｍである。 FIG. 4 is an optical microscope image of the sample surface for Raman mapping. Graphene was grown directly on SiO 2 from a solid carbon source by the procedure of FIG. The graphene pattern has a width of about 10 μm and a length of about 200 μm.
　図５Ａは、図４のサンプルのＤバンドのラマン画像、図５Ｂは図４のサンプルのＧバンドのラマン画像、図５Ｃは図４のサンプルの２Ｄバンドのラマン画像である。Ｄバンド、Ｇバンド、及び２Ｄバンドは、一般的なグラフェンのラマン散乱スペクトルのピークが帰属するバンドである。 5A is a D-band Raman image of the sample of FIG. 4, FIG. 5B is a G-band Raman image of the sample of FIG. 4, and FIG. 5C is a 2D-band Raman image of the sample of FIG. The D band, G band, and 2D band are bands to which the peak of the Raman scattering spectrum of general graphene belongs.
　図５ＡのＤバンドは、結晶の乱れ、欠陥等のグラフェンの結晶構造に由来するバンドである。励起波長にも依存するが、１２７０ｃｍ-1～１４５０ｃｍ-1の波数（ラマンシフト）にピークが観察されると、グラフェンが多結晶または欠陥を含むことを示している。 The D band in FIG. 5A is a band derived from the crystal structure of graphene such as crystal disorder and defects. Although it depends on the excitation wavelength, the peak wave number (Raman shift) of 1270 cm -1 ~ 1450 cm -1 is observed, indicating that graphene comprises polycrystalline or defective.
　図５ＢのＧバンドは１５８０ｃｍ-1付近にある。Ｇバンドのピークは、炭素原子の６員環の面内伸縮振動に起因するピークであり、グラフェンの存在やグラフェンの層数を表わす指標として用いられる。層数が多いほど、低周波側（波数が少ない側）にシフトする。 The G band in Fig. 5B is near 1580 cm-1. The peak of the G band is a peak caused by the in-plane expansion and contraction vibration of the 6-membered ring of the carbon atom, and is used as an index showing the presence of graphene and the number of layers of graphene. The larger the number of layers, the lower the frequency side (the side with the smaller wave number).
　図５Ｃの２Ｄバンドは、グラフェンの構成に由来するピークであり、２つのフォノンによる二次のラマン散乱を表わす。２Ｄバンドのピークも、グラフェンの存在やグラフェンの層数の特定に用いられる。 The 2D band in FIG. 5C is a peak derived from the composition of graphene and represents secondary Raman scattering by two phonons. The peak of the 2D band is also used to identify the presence of graphene and the number of graphene layers.
　図５Ａ～５Ｃに示すように、二次元平面の同じ位置で、グラフェンに特徴的なラマンピークであるＤバンド、Ｇバンド、及び２Ｄバンドのそれぞれが測定されている。このマッピング結果から、図４のパターンが、基板上に直接形成されたグラフェンのパターンであることが確認される。 As shown in FIGS. 5A to 5C, the D band, G band, and 2D band, which are Raman peaks characteristic of graphene, are measured at the same position on the two-dimensional plane. From this mapping result, it is confirmed that the pattern of FIG. 4 is a graphene pattern formed directly on the substrate.
　図６は、実施形態の光デバイスの一例である発光素子１０の模式図である。発光素子１０は、基板１１を覆う絶縁膜１２の上に直接成長したグラフェン１７の薄膜を利用して作製される。所定のパターンに形成されたグラフェン１７の薄膜と電気的に接続される電極３１と電極３２が、設けられている。電極３１と電極３２は、たとえば蒸着により、クロム（Ｃｒ）とパラジウム（Ｐｄ）をそれぞれ１ｎｍ～２００ｎｍの厚さで、この順に成膜することで形成される。一例として、Ｃｒを５ｎｍ、Ｐｄを１４５ｎｍ成膜する。電極３１と電極３２は、発光素子１０を搭載するチップにワイヤーボンディングされており（ボンディングワイヤの図示は省略）、電源と接続されている。 FIG. 6 is a schematic view of a light emitting element 10 which is an example of the optical device of the embodiment. The light emitting element 10 is manufactured by using a thin film of graphene 17 grown directly on the insulating film 12 covering the substrate 11. Electrodes 31 and electrodes 32 that are electrically connected to the thin film of graphene 17 formed in a predetermined pattern are provided. The electrode 31 and the electrode 32 are formed by forming chromium (Cr) and palladium (Pd) with a thickness of 1 nm to 200 nm in this order, for example, by vapor deposition. As an example, Cr is formed at 5 nm and Pd is formed at 145 nm. The electrodes 31 and 32 are wire-bonded to a chip on which the light emitting element 10 is mounted (bonding wires are not shown), and are connected to a power source.
　発光素子１０の表面に保護膜またはキャップ層を形成してもよい。保護膜を設けることで、酸素との反応によるグラフェンの損傷を防ぐことができ、発光素子１０を大気中で動作させることができる。 A protective film or a cap layer may be formed on the surface of the light emitting element 10. By providing the protective film, it is possible to prevent damage to graphene due to the reaction with oxygen, and the light emitting element 10 can be operated in the atmosphere.
　グラフェン１７の薄膜は、図３の光学顕微鏡像で示したように、基板上の所定の位置に任意の形状で、固体炭素源から直接形成されるので、発光素子１０をアレイ状に配置するこが容易である。発光素子１０のアレイでは、リフトオフ法で得られた固体炭素源のパターンから、グラフェン１７の各パターンが安定して形成されている。蒸着用のメタルマスクを用いて、グラフェン１７の各薄膜パターンに対応する電極パターンを、一度に形成することができる。この手法は、グラフェンの転写等が不要なので、工程が簡単で、かつ工程数を低減できる。 As shown in the optical microscope image of FIG. 3, the thin film of graphene 17 is formed at a predetermined position on the substrate in an arbitrary shape directly from the solid carbon source, so that the light emitting elements 10 are arranged in an array. Is easy. In the array of the light emitting elements 10, each pattern of graphene 17 is stably formed from the pattern of the solid carbon source obtained by the lift-off method. An electrode pattern corresponding to each thin film pattern of graphene 17 can be formed at once by using a metal mask for vapor deposition. Since this method does not require transfer of graphene or the like, the process is simple and the number of processes can be reduced.
　図７は、炭素固体源から直接成長したグラフェンを用いた発光素子の光学顕微鏡像である。電極を通して見える横長の影が、基板上のグラフェン１７のパターンである。グラフェン１７のパターンの幅が１０μｍ、グラフェン１７とオーバーラップして配置される一対の電極間の距離は１０μｍであり、基板上に１０μｍ×１０μｍの発光面が形成されている。 FIG. 7 is an optical microscope image of a light emitting device using graphene grown directly from a solid carbon source. The horizontally long shadow seen through the electrodes is the pattern of graphene 17 on the substrate. The width of the pattern of the graphene 17 is 10 μm, the distance between the pair of electrodes arranged so as to overlap the graphene 17 is 10 μm, and a light emitting surface of 10 μm × 10 μm is formed on the substrate.
　図８は、図７のグラフェン発光素子の赤外発光を示す赤外カメラ像である。発光素子の電極間に電圧を印加すると、グラフェン１７に電流が流れ込み、ジュール熱による熱放射が起きて、発光する。ここでは、１７Ｖの電圧を印加し、５秒の積算で観察した。基板上に直接形成されたグラフェンのパターンのうち、一対の電極で挟まれた領域が明るく発光しているのがわかる。 FIG. 8 is an infrared camera image showing infrared emission of the graphene light emitting device of FIG. 7. When a voltage is applied between the electrodes of the light emitting element, a current flows into the graphene 17, heat radiation due to Joule heat occurs, and light is emitted. Here, a voltage of 17 V was applied, and the observation was carried out for 5 seconds. It can be seen that in the graphene pattern formed directly on the substrate, the region sandwiched between the pair of electrodes emits bright light.
　一般に、トランジスタ、センサ等の電子デバイスへの応用においては、移動度の高いグラフェンはチャネル材料として利用される。高速で消費電力の小さい電子デバイスを作製するためには、高品質なグラフェンが必要とされ、多結晶性に起因するＤバンドのピークはない方が望ましい。だからといって、実施形態のグラフェンの直接成長を、電子デバイスへの適用に妨げるものではなく、基板上に所望のパターンで直接形成されるグラファイトを利用して、トランジスタ等を形成してもよい。 Generally, graphene with high mobility is used as a channel material in applications to electronic devices such as transistors and sensors. High-quality graphene is required to produce high-speed, low-power-consumption electronic devices, and it is desirable that there is no D-band peak due to polycrystalline properties. That said, the direct growth of graphene of the embodiment is not hindered by its application to electronic devices, and graphite or the like may be formed using graphite formed directly on the substrate in a desired pattern.
　一方、実施形態の発光素子１０への応用においては、図５ＡのようにＤバンドのラマンピークが観察されるグラフェンを用いても、図８のように明るい発光が得られる。このグラフェンは、発光素子だけでなく、光検出器、光変調器等に用いることができる。 On the other hand, in the application to the light emitting device 10 of the embodiment, bright light emission can be obtained as shown in FIG. 8 even if graphene in which the Raman peak of the D band is observed as shown in FIG. 5A is used. This graphene can be used not only for light emitting elements but also for photodetectors, light modulators and the like.
　グラフェンは広い波長域で、特に赤外光を吸収する。グラフェンを光吸収層として用いた光検出素子をアレイ状に並べ、素子の各々にバイアスを印加して光吸収により生じたキャリアを引き出すことで、赤外線センサを構成することができる。 Graphene absorbs infrared light in a wide wavelength range. An infrared sensor can be configured by arranging photodetection elements using graphene as a light absorption layer in an array and applying a bias to each of the elements to draw out carriers generated by light absorption.
　グラフェンはまた、ナノ材料特有の小さな熱容量と、基板への熱の大きな逸脱により、従来の白熱電球と比べて１０7倍以上も高速な、１００ｐｓ以下の緩和時間で変調が可能である。すなわち、グラフェンに印加する電圧のオン／オフを切り替えることで、高速の発光強度の変調が実現される。また、実施形態でデバイス基板に作製されたグラフェンは、微小な熱源としても利用可能である。グラフェンをヒーター等の熱源として熱光学効果を組み合わせることで、光変調器や光スイッチを作製することができる。 Graphene also a small heat capacity of nanomaterials specific, the large deviation of heat to the substrate, 10 7 times or more as compared with conventional incandescent bulbs high speed, it is possible to modulate the following relaxation time 100 ps. That is, by switching the voltage applied to graphene on / off, high-speed modulation of emission intensity is realized. In addition, the graphene produced on the device substrate in the embodiment can also be used as a minute heat source. Optical modulators and optical switches can be manufactured by combining graphene as a heat source such as a heater and combining thermo-optical effects.
　情報通信量の急速な増大を背景に、次世代通信の基盤技術として光インターコネクトやシリコンフォトニクスが大きな期待を集めている。実施形態のグラフェン成長技術は、発光素子、受光素子、光変調器などの光デバイスを容易に集積化でき、光通信の分野への適用に好適である。実施形態のグラフェン成長技術は、光デバイスだけでなく、電子デバイスに適用されてもよい。 Against the background of the rapid increase in the amount of information communication, optical interconnects and silicon photonics are highly expected as basic technologies for next-generation communication. The graphene growth technique of the embodiment can easily integrate optical devices such as a light emitting element, a light receiving element, and an optical modulator, and is suitable for application in the field of optical communication. The graphene growth technique of the embodiment may be applied not only to optical devices but also to electronic devices.
　＜第２実施形態＞
　第２実施形態では、大面積のグラフェンを任意の基板上に形成する。密着性の高い安定したグラフェンの作製法は、パターン化されていない大面積のグラフェンの作製にも適用可能である。 <Second Embodiment>
In the second embodiment, a large area of graphene is formed on an arbitrary substrate. The method for producing stable graphene with high adhesion can also be applied to the production of unpatterned large-area graphene.
　図９Ａ～図９Ｄは第２実施形態のグラフェンの作製工程図である。第２実施形態では、絶縁体、シリコン、ゲルマニウム、化合物半導体、酸化物半導体など、デバイス作製に用いられる基板の表面に、グラフェンを直接成長する。第１実施形態と同様に、デバイス作製のためのグラフェンの転写は不要である。 9A-9D are process diagrams for producing graphene according to the second embodiment. In the second embodiment, graphene is directly grown on the surface of a substrate used for device fabrication, such as an insulator, silicon, germanium, a compound semiconductor, and an oxide semiconductor. As in the first embodiment, no transfer of graphene for device fabrication is required.
　図９Ａで、シリコン酸化膜等の絶縁膜４２で覆われた基板４１の全面に、薄い金属膜４３、固体炭素源の薄膜４４、及び金属触媒層４５を、この順で形成する。以下で説明する実施形態では、固体炭素源としてアモルファスカーボン（ａ-Ｃ）の薄膜を用いるが、炭化ケイ素（ＳｉＣ）、ポリマー材料など、炭素を含有し、かつ薄膜形成が可能なその他の材料を用いてもよい。基板４１としては、デバイス作製に利用することのできるどのような基板を用いてもよい。 In FIG. 9A, a thin metal film 43, a thin film 44 of a solid carbon source, and a metal catalyst layer 45 are formed in this order on the entire surface of a substrate 41 covered with an insulating film 42 such as a silicon oxide film. In the embodiments described below, a thin film of amorphous carbon (aC) is used as the solid carbon source, but other materials containing carbon and capable of forming a thin film such as silicon carbide (SiC) and a polymer material are used. You may use it. As the substrate 41, any substrate that can be used for manufacturing the device may be used.
　金属膜１３は、主として固体炭素源の薄膜４４と基板４１（または絶縁膜４２）との間の密着性を高める働きをするが、グラフェンの成長に寄与させてもよい。その場合は、グラフェンの成長に適した触媒金属で金属膜４３を形成してもよい。 The metal film 13 mainly functions to enhance the adhesion between the thin film 44 of the solid carbon source and the substrate 41 (or the insulating film 42), but may contribute to the growth of graphene. In that case, the metal film 43 may be formed of a catalyst metal suitable for the growth of graphene.
　図９Ｂで、金属膜４３、固体炭素源の薄膜４４、及び金属触媒層４５の積層を有する基板全体を、１０００～１１００℃の高温で、不活性ガス雰囲気下で数分間、アニールする。この熱処理により、固体炭素源から昇華した炭素が金属触媒層４５に固溶し、また、一部、金属膜４３にも固溶し、グラフェンが生成される。 In FIG. 9B, the entire substrate having the metal film 43, the thin film 44 of the solid carbon source, and the metal catalyst layer 45 laminated is annealed at a high temperature of 1000 to 1100 ° C. for several minutes in an inert gas atmosphere. By this heat treatment, the carbon sublimated from the solid carbon source is solid-solved in the metal catalyst layer 45, and is partially dissolved in the metal film 43 to form graphene.
　図９Ｃで、グラフェン４７の表面に残留した金属触媒層４５を除去する。残存する金属触媒層１５は、酸処理等によって除去される。これにより、図９Ｄで、基板４１の全面に、グラフェン４７を得ることができる。大面積のグラフェン４７は、基板４１（または絶縁膜４２）に密着保持されており、その後の工程で、エッチング等の加工を受けても、剥がれにくい。 In FIG. 9C, the metal catalyst layer 45 remaining on the surface of graphene 47 is removed. The remaining metal catalyst layer 15 is removed by acid treatment or the like. As a result, in FIG. 9D, graphene 47 can be obtained on the entire surface of the substrate 41. The graphene 47 having a large area is closely held to the substrate 41 (or the insulating film 42), and is not easily peeled off even if it is subjected to processing such as etching in the subsequent steps.
　図１０は、図９の方法で作製された大面積グラフェンの光学顕微像である。シリコン基板上に、厚さ５ｎｍのＮｉ膜を蒸着で成膜し、厚さ５ｎｍのアモルファスカーボンの薄膜を蒸着で形成し、厚さ２０ｎｍのＮｉ膜を蒸着で形成し、アルゴン雰囲気中でアニールを行っている。シリコン基板の全面に、グラフェン膜が安定して形成されている。 FIG. 10 is an optical microscopic image of large-area graphene produced by the method of FIG. A 5 nm thick Ni film is deposited on a silicon substrate by thin film deposition, a 5 nm thick amorphous carbon thin film is formed by thin film deposition, a 20 nm thick Ni film is formed by thin film deposition, and annealing is performed in an argon atmosphere. Is going. A graphene film is stably formed on the entire surface of the silicon substrate.
　本発明により、以下の効果が得られる。
（１）炭素固体源と基板の間に薄い金属膜を配置することで、炭素固体源と基板との付着力を強めることができる。後のリフトオフ処理で、不要な部分の固体炭素源と金属触媒層を除去する際に、目的のパターンを形成する固体炭素源が基板表面から分離することを防止できる。
（２）基板全体を覆う大面積のグラフェン膜を安定して形成できるだけでなく、あらかじめ設計した任意の大きさ、任意のパターンで、基板上の任意の位置に、グラフェンの薄膜を直接形成することができる。触媒金属のエッチング、グラフェンのエッチング、グラフェンの転写等の工程が不要である。
（３）基板上の好ましくない領域にカーバイド（炭素化合物）が残留することを防止できる。
（４）基板上の所望の位置に直接形成されるグラフェンを利用して作製される光デバイスは、アレイ化と集積化に適している。 According to the present invention, the following effects can be obtained.
(1) By arranging a thin metal film between the carbon solid source and the substrate, the adhesive force between the carbon solid source and the substrate can be strengthened. In the subsequent lift-off treatment, when the solid carbon source and the metal catalyst layer in the unnecessary portion are removed, it is possible to prevent the solid carbon source forming the desired pattern from separating from the substrate surface.
(2) Not only can a large-area graphene film covering the entire substrate be stably formed, but also a thin film of graphene can be directly formed at an arbitrary position on the substrate with an arbitrary size and an arbitrary pattern designed in advance. Can be done. No steps such as etching of the catalyst metal, etching of graphene, and transfer of graphene are required.
(3) It is possible to prevent the carbide (carbon compound) from remaining in an unfavorable region on the substrate.
(4) Optical devices made using graphene formed directly at desired positions on the substrate are suitable for arraying and integration.
　この出願は、２０１９年８月８日に出願された日本国特許出願第２０１９－１４６７７９号に基づきその優先権を主張するものであり、その全内容を含むものである。 This application claims its priority based on Japanese Patent Application No. 2019-146779 filed on August 8, 2019, and includes the entire contents thereof.
１０　発光素子（光デバイス）
１１、４１　基板
１２、４２　絶縁膜
１３、４３　金属膜
１４、４４　固体炭素源の薄膜
１５　金属触媒層
１７、４７　グラフェン
２１　固体炭素源を含むパターン
２３　レジストマスク
２４　開口
３１、３２　電極 10 Light emitting element (optical device)
11, 41 Substrates 12, 42 Insulating film 13, 43 Metal film 14, 44 Thin film of solid carbon source 15 Metal catalyst layer 17, 47 Graphene 21 Pattern containing solid carbon source 23 Resist mask 24 Opening 31, 32 Electrodes

Claims (9)

  1. 　デバイス作製に用いる基板の上に第１の金属膜を形成し、
    　前記第１の金属膜の上に固体炭素源の薄膜を形成し、
    　前記固体炭素源の薄膜の上に第２の金属膜を形成し、
    　前記第１の金属膜、前記固体炭素源の薄膜、及び前記第２の金属膜がこの順で重ねられた積層体に熱処理を施して、前記基板の上にグラフェンを直接成長する、
    ことを特徴とするグラフェン作製方法。     A first metal film is formed on the substrate used for device fabrication,
    A thin film of solid carbon source is formed on the first metal film,
    A second metal film is formed on the thin film of the solid carbon source,
    The first metal film, the thin film of the solid carbon source, and the laminate in which the second metal film is laminated in this order are heat-treated to grow graphene directly on the substrate.
    A graphene production method characterized by this.
  2. 　デバイス作製に用いる基板の上に、第１の金属膜、固体炭素源の薄膜、及び第２の金属膜がこの順で重ねられた積層体のパターンを形成し、
    　前記積層体を熱処理することで前記固体炭素源をグラフェンに変えて、前記基板の上に前記パターンのグラフェン薄膜を形成する、
    ことを特徴とするグラフェン作製方法。     A pattern of a laminated body in which a first metal film, a thin film of a solid carbon source, and a second metal film are laminated in this order is formed on a substrate used for manufacturing a device.
    By heat-treating the laminate, the solid carbon source is changed to graphene, and a graphene thin film having the pattern is formed on the substrate.
    A graphene production method characterized by this.
  3. 　前記積層体のパターンを、リフトオフ法で形成することを特徴とする請求項２に記載のグラフェン作製方法。 The graphene production method according to claim 2, wherein the pattern of the laminated body is formed by a lift-off method.
  4. 　前記第１の金属膜と前記第２の金属膜を同じ材料で形成することを特徴とする請求項１または２に記載のグラフェン作製方法。 The graphene production method according to claim 1 or 2, wherein the first metal film and the second metal film are formed of the same material.
  5. 　前記第１の金属薄膜を、１分子層以上、１００ｎｍ以下の厚さで形成することを特徴とする請求項１～４のいずれか１項に記載のグラフェン作製方法。 The graphene production method according to any one of claims 1 to 4, wherein the first metal thin film is formed with a thickness of one molecular layer or more and 100 nm or less.
  6. 　前記固体炭素源の薄膜を、アモルファスカーボンまたはポリマーで形成することを特徴とする請求項１～５のいずれか１項に記載のグラフェン作製方法。 The graphene production method according to any one of claims 1 to 5, wherein the thin film of the solid carbon source is formed of amorphous carbon or a polymer.
  7. 　デバイス作製に用いる基板の上に、第１の金属膜、固体炭素源の薄膜、及び第２の金属膜がこの順で重ねられた積層体のパターンを形成し、
    　前記積層体を熱処理することで、前記固体炭素源をグラフェンに変えて、前記基板上に前記パターンのグラフェン薄膜を形成し、
    　前記グラフェン薄膜と電気的に接続される電極を形成する、
    ことを特徴とする光デバイスの作製方法。     A pattern of a laminated body in which a first metal film, a thin film of a solid carbon source, and a second metal film are laminated in this order is formed on a substrate used for manufacturing a device.
    By heat-treating the laminate, the solid carbon source is changed to graphene, and a graphene thin film having the pattern is formed on the substrate.
    Forming an electrode that is electrically connected to the graphene thin film,
    A method for manufacturing an optical device.
  8. 　前記グラフェン薄膜は、発光素子の発光層、または受光素子の光吸収層であることをと特徴とする請求項７に記載の光デバイスの作製方法。 The method for manufacturing an optical device according to claim 7, wherein the graphene thin film is a light emitting layer of a light emitting element or a light absorbing layer of a light receiving element.
  9. 　前記グラフェン薄膜を前記基板上の所定の位置にアレイ状に配置し、
    　前記グラフェン薄膜の各々に前記電極を設けて光デバイスのアレイを作製する、
    ことを特徴とする請求項７または８に記載の光デバイスの作製方法。     The graphene thin films are arranged in an array at predetermined positions on the substrate.
    An array of optical devices is prepared by providing the electrodes on each of the graphene thin films.
    The method for manufacturing an optical device according to claim 7 or 8, wherein the optical device is manufactured.
PCT/JP2020/028534 2019-08-08 2020-07-22 Graphene production method and method for producing optical device WO2021024818A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011168473A (en) * 2010-01-21 2011-09-01 Hitachi Ltd Substrate having graphene film grown thereon and electro-optical integrated circuit device using the same
JP2012246215A (en) * 2011-05-27 2012-12-13 Pohang Univ Of Science & Technology Academy-Industry Cooperation Method for producing carbon thin film, electronic element containing the same, and electrochemical element containing the same
JP2017095327A (en) * 2015-11-27 2017-06-01 学校法人 名城大学 Manufacturing method of graphene substrate

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011168473A (en) * 2010-01-21 2011-09-01 Hitachi Ltd Substrate having graphene film grown thereon and electro-optical integrated circuit device using the same
JP2012246215A (en) * 2011-05-27 2012-12-13 Pohang Univ Of Science & Technology Academy-Industry Cooperation Method for producing carbon thin film, electronic element containing the same, and electrochemical element containing the same
JP2017095327A (en) * 2015-11-27 2017-06-01 学校法人 名城大学 Manufacturing method of graphene substrate

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