Nanocrystalline graphene and method for forming nanocrystalline graphene

Abstract

Nanocrystalline graphene and a method for manufacturing the same are presented. The nanocrystalline graphene comprises a plurality of grains formed by stacking a plurality of graphene sheets, has a grain density of 500 ea / um² or more, and has a root mean square (RMS) surface roughness of 0.1 or more and 1.0 or less. By having a grain density and surface roughness within the above ranges, nanocrystalline graphene capable of covering a large area on a substrate with a thin thickness can be provided.

Description

Technology Field

[0001] The invention relates to nanocrystalline graphene and a method for manufacturing nanocrystalline graphene, and more specifically, to nanocrystalline graphene and a method for forming the nanocrystalline graphene by directly growing it on a substrate using a plasma chemical vapor deposition method. Background Technology

[0002] Graphene is a crystalline material in which carbon atoms are connected in two dimensions to form a hexagonal honeycomb structure, and it has a very thin thickness at the atomic level. This graphene can be synthesized by chemical vapor deposition (CVD) or obtained by peeling off graphite layer by layer. The problem to be solved

[0003] An exemplary embodiment provides nanocrystalline graphene and a method for forming the nanocrystalline graphene by growing it directly on a substrate using a plasma chemical vapor deposition process. means of solving the problem

[0004] In one aspect,

[0005] It includes a plurality of grains formed by stacking a plurality of graphene sheets,

[0006] 500 ea / um 2 Nanocrystalline graphene having a grain density greater than or equal to 0.1 and a root mean square (RMS) surface roughness greater than or equal to 1.0 is provided.

[0007] The above nanocrystalline graphene may have a thickness of 10 nm or less. For example, the above nanocrystalline graphene may have a thickness of 2 nm or less.

[0008] The above nanocrystalline graphene may have a D / G peak ratio of 1.0 or higher and a 2D / G peak ratio of 0.1 or higher in the Raman spectrum.

[0009] The above nanocrystalline graphene may be substrate-based graphene formed on a non-catalytic substrate.

[0010] The above nanocrystalline graphene can be formed by directly growing it on a non-catalyst substrate at a temperature of 700°C or lower by a plasma chemical vapor deposition process.

[0011] In other aspects,

[0012] A step of injecting a reaction gas containing a carbon source gas and an inert gas into a reaction chamber;

[0013] A step of generating a plasma of the reaction gas within the reaction chamber; and

[0014] A step of forming nanocrystalline graphene by directly growing it on a non-catalytic substrate using a plasma of the reaction gas at a temperature of 700℃ or lower;

[0015] A method for manufacturing nanocrystalline graphene according to claim 1, comprising

[0016] The flow rate of the above inert gas may be in the range of 600 to 1600 sccm.

[0017] The above reaction gas may not contain hydrogen gas or may contain hydrogen gas further. If the above reaction gas contains hydrogen gas further, the volume ratio of the carbon source, inert gas and hydrogen gas may be 1: 0.01 to 5000: 0 to 300.

[0018] The carbon source may include at least one of a hydrocarbon gas and a vapor of a carbon-containing liquid precursor. The inert gas may include at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas, and xenon gas.

[0019] The above nanocrystalline graphene can be grown at a process temperature of 180°C to 700°C.

[0020] The above nanocrystalline graphene can be grown at a process pressure of 0.001 Torr to 10 Torr.

[0021] The above plasma may be generated by at least one RF (Radio Frequency) plasma generator or at least one MW (Microwave) plasma generator. The plasma may include an RF plasma having a frequency range of 3 to 100 MHz or a MW plasma having a frequency range of 0.7 to 2.5 GHz.

[0022] The power for generating the plasma of the above reaction gas can be 10W to 4000W.

[0023] The above substrate may include at least one of a group IV semiconductor material, a semiconductor compound, a metal, and an insulating material.

[0024] The above group IV semiconductor material may include Si, Ge, or Sn. The above semiconductor compound may include a material in which at least two elements selected from Si, Ge, C, Zn, Cd, Al, Ga, In, B, C, N, P, S, Se, As, Sb, and Te are combined. The above metal may include at least one selected from Cu, Mo, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, and Gd.

[0025] The insulating material may comprise at least one of Si, Al, Hf, Zr, Zn, Ti, Ta, W, and Mn, or at least one of oxides, nitrides, carbides, and derivatives thereof selected from at least one of Si, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, Cu, Mo, and Gd. At least one of the oxides, nitrides, carbides, and derivatives thereof may further comprise H.

[0026] The above substrate may further include a dopant.

[0027] The method for manufacturing the nanocrystalline graphene described above may further include a step of pretreating the surface of the substrate using a reducing gas before growing the nanocrystalline graphene.

[0028] The reducing gas may include at least one of hydrogen, nitrogen, chlorine, fluorine, ammonia, and derivatives thereof. Here, the reducing gas may further include an inert gas.

[0029] The method for manufacturing the nanocrystalline graphene described above may further include the step of first forming the nanocrystalline graphene on the substrate, and then secondarily forming additional nanocrystalline graphene on the nanocrystalline graphene by adjusting the mixing ratio of the reaction gas.

[0030] The above reaction gas may not contain hydrogen gas or may contain additional hydrogen gas. Effects of the invention

[0031] According to exemplary embodiments, it comprises a plurality of grains formed by stacking a plurality of graphene sheets, and 500 ea / um 2 Nanocrystalline graphene having a grain density greater than or equal to 0.1 and a root mean square (RMS) surface roughness greater than or equal to 1.0 can be formed using a plasma chemical vapor deposition process. By having grain density and surface roughness within the above ranges, nanocrystalline graphene capable of covering a large area on a substrate with a thin thickness can be provided. In this plasma chemical vapor deposition process, the reaction gas includes a carbon source, an inert gas, and a hydrogen gas, and by activating the surface of the substrate with a plasma of the inert gas, nanocrystalline graphene can be directly grown and formed on the surface of the substrate even at a relatively low temperature of 700°C or lower.

[0032] Since the technology for directly growing and forming nanocrystalline graphene on the surface of a substrate at a relatively low temperature can be applied in CMOS (Complementary Metal-Oxide-Semiconductor) processes, it can be applied to form elements of semiconductor devices such as barrier metals or source / drain contacts, or to manufacture pellicles for photolithography equipment. Brief explanation of the drawing

[0033] FIG. 1 is a diagram illustrating the growth of nanocrystalline graphene according to an exemplary embodiment. FIG. 2 exemplarily illustrates the stacking process of graphene sheets according to the growth time of nanocrystalline graphene in one embodiment. Figures 3 to 6 are atomic force microscope (AFM) images showing the surface roughness and thickness of nanocrystalline graphene grown after growth times of 10 seconds, 20 seconds, 35 seconds, and 90 seconds, respectively. Figure 7 is a graph showing the thickness and grain size of nanocrystalline graphene according to growth time. Figure 8 shows the results of measuring the grain density and surface roughness of nanocrystalline graphene according to the flow rate of Ar flow in the plasma chemical vapor deposition process. Fig. 9 shows a grain density of 500 ea / um 2 Cases less than and 500 ea / um 2 This is a graph showing the relationship between the thickness and surface roughness (RMS) of nanocrystalline graphene in the above case. Fig. 10 shows a grain density of 430 ea / um 2 This is an AFM image of nanocrystalline graphene. Fig. 11 shows a grain density of 680 ea / um 2 This is an AFM image of nanocrystalline graphene. Fig. 12 shows a grain density of 1100 ea / um 2 This is an AFM image of nanocrystalline graphene. Fig. 13a shows 430 ea / um 2 Figure 13b is an AFM image of graphene on a substrate having a low grain density, and is an AFM image of tungsten (W) deposited on the graphene on the substrate. Fig. 14a shows 1100 ea / um 2 Figure 14b is an AFM image of graphene on a substrate having a high grain density, and is an AFM image of tungsten (W) deposited on the graphene on the substrate. Specific details for implementing the invention

[0034] The present inventive concept described below is subject to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present inventive concept to specific embodiments and should be understood to include all modifications, equivalents, or substitutions that fall within the scope of the description of the present inventive concept.

[0035] The terms used below are used merely to describe specific embodiments and are not intended to limit the creative concept. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the following, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof. The " / " used below may be interpreted as "and" or "or" depending on the context.

[0036] In the drawings, thicknesses have been enlarged or reduced to clearly represent various layers and regions. Throughout the specification, the same reference numerals have been used for similar parts. Throughout the specification, when a part such as a layer, film, region, or plate is described as being "on" or "above" another part, this includes not only cases where it is directly above another part but also cases where there is another part in between. Throughout the specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0037] Nanocrystalline graphene and a method for manufacturing the same according to exemplary embodiments are described in more detail below.

[0038] Nanocrystalline graphene according to one embodiment comprises a plurality of grains formed by stacking a plurality of graphene sheets, and 500 ea / um 2 It has a grain density greater than or equal to 0.1 and a root mean square (RMS) surface roughness greater than or equal to 1.0.

[0039] The above grains include crystals having a nanoscale size, for example, crystals with a size of approximately 100 nm or less.

[0040] During research into the potential applications of graphene due to the limitations of existing materials caused by device scaling, advantages have been confirmed in various parts, such as barriers and capping / contact layers. For industrial application, however, large-area, uniform graphene direct growth technology is currently required.

[0041] When growing graphene directly on a substrate, lateral diffusion must occur effectively after CH3 radicals are adsorbed in order to increase the grain size. In the case of graphene growth on Si, the adsorption energy is 2.6–3 eV or higher depending on the presence or absence of dangling bonds in the nearest neighbor, so it is expected that radicals will not move from the chemisorption site. On the other hand, grain growth on graphene is more dominant than on Si, but as growth proceeds only on the seed, the root mean square (RMS) surface roughness increases, making it difficult to form full-cover large-area graphene.

[0042] FIG. 1 is a diagram illustrating the growth of nanocrystalline graphene according to an exemplary embodiment.

[0043] As shown in Figure 1, physical parameters and coverage may differ depending on the morphology. The simulation results of the physical parameters and coverage values ​​for different types of exemplary graphene morphologies, A, B, and C, are summarized in Table 1 below.

[0044] Morphology Average THK(XPS, nm) Grain size(AFM, nm) Grain density(ea / unit area) RMS(AFM, nm) k L / k V (at single grain) Coverage(%) A 1.26 42 2 1.23 42 / 6 75 B 1.26 12 8 1.50 12 / 7 85.7 C 1.26 12 8 1.31 12 / 5 100

[0045] For graphene of the same thickness (average thickness), it is not possible to create a structure that satisfies full coverage based solely on grain size (or density) or RMS individual indicators. To satisfy barrier properties and resistance characteristics, a graphene structure with grain density and RMS within a specific numerical range is absolutely necessary.

[0046] Accordingly, the inventors, in forming nanocrystalline graphene comprising a plurality of grains formed by stacking a plurality of graphene sheets using a plasma chemical vapor deposition process, 500 ea / um 2 The present invention was arrived at because it was possible to manufacture nanocrystalline graphene capable of full coverage of a large area on a substrate with a thin thickness by having a grain density of the above and a root mean square (RMS) surface roughness of 0.1 or more and 1.0 or less.

[0047] FIG. 2 exemplarily illustrates the stacking process of graphene sheets according to the growth time of nanocrystalline graphene in one embodiment.

[0048] Figures 3 to 6 are atomic force microscope (AFM) images showing the surface roughness and thickness of nanocrystalline graphene grown after growth times of 10 seconds, 20 seconds, 35 seconds, and 90 seconds, respectively.

[0049] As seen in Figures 2 and 6, once the seed is formed, it can be seen that the surface roughness increases as graphene grows on the graphene sheet.

[0050] Figure 7 is a graph showing the thickness and grain size of nanocrystalline graphene according to growth time. As seen in Figure 7, it can be seen that as the growth time increases, the horizontal growth rate becomes greater than the thickness growth rate.

[0051] Nanocrystalline graphene according to one embodiment has 500 ea / um 2It is possible to provide graphene that has a grain density greater than or equal to the above and a root mean square (RMS) surface roughness greater than or equal to 0.1 and less than or equal to 1.0, which allows for full coverage of a large area with a thin thickness by increasing the grain density.

[0052] Nanocrystalline graphene was grown by controlling the flow rate of Ar in a plasma chemical vapor deposition process according to an embodiment described below, and the results of measuring the grain density and surface roughness of the nanocrystalline graphene according to the flow rate of Ar are shown in FIG. 8.

[0053] As shown in Fig. 8, it can be seen that as the Ar flow velocity increases, the grain density increases and the surface roughness decreases below a certain level. When the Ar flow velocity is less than 600 sccm, the grain density is 500 ea / um. 2 It is undesirable to manufacture nanocrystalline graphene of less than [amount].

[0054] Fig. 9 shows a grain density of 500 ea / um 2 Cases less than and 500 ea / um 2 This is a graph showing the relationship between thickness and surface roughness (RMS) of nanocrystalline graphene in the above cases. The grain density is 500 ea / um 2 In cases below this level, surface roughness tends to increase as the thickness of nanocrystalline graphene increases, whereas when the grain density is 500 ea / um 2 In the above case, it can be seen that even if the thickness of nanocrystalline graphene increases, the increase in surface roughness is suppressed, allowing for the production of uniform, high-quality graphene.

[0055] FIGS. 10 to 12 are AFM images showing the surface roughness and thickness of some of the results of FIG. 8, respectively, of nanocrystalline graphene, where FIG. 10 shows a grain density of 430 ea / um. 2 This is an AFM image of phosphorus nanocrystalline graphene, and Fig. 11 shows a grain density of 680 ea / µm. 2This is an AFM image of phosphorus nanocrystalline graphene, and Fig. 12 shows a grain density of 1100 ea / µm 2 This is an AFM image of nanocrystalline graphene.

[0056] As shown in Fig. 10, the grain density is 430 ea / um 2 In the case of nanocrystalline graphene with an RMS of 0.98 nm, as indicated by the arrow, it can be seen that numerous defect sites where grains are not formed between grains are found, and their area is large. This indicates low coverage.

[0057] As shown in Fig. 11, the grain density is 680 ea / um 2 In the case of nanocrystalline graphene with an RMS of 0.62 nm, the area of ​​defect sites where grains are not formed decreased, and thus the coverage area also decreased. This indicates improved coverage.

[0058] As shown in Fig. 12, the grain density is 1100 ea / um 2 In the case of nanocrystalline graphene with an RMS of 0.54 nm, no defect sites were found, and it was found to be completely covered.

[0059] From the above results, nanocrystalline graphene is 500 ea / um 2 It can be seen that by having a grain density greater than or equal to 0.1 and a root mean square (RMS) surface roughness less than or equal to 1.0, it is possible to cover a large area with a thin thickness.

[0060] The above nanocrystalline graphene may have a thickness of 10 nm or less. For example, the above nanocrystalline graphene may have a thickness of 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, or 2 nm or less. Even in such thin thickness ranges, large-area nanocrystalline graphene with high grain density and improved surface roughness can be provided.

[0061] Meanwhile, sp for total carbon 2 The proportion of carbons having a bonding structure can be obtained by measuring D-parameters through X-ray Photoelectron Spectroscopy (XPS) analysis. Specifically, in XPS analysis, sp⁻¹ for the total carbon 2 The peak shape of the Auger spectrum for carbon varies depending on the proportion of carbon having a bonded structure. In the D-parameter spectrum formed by differentiating this peak shape, the interval between the highest and lowest points becomes the D-parameter. Therefore, by measuring the D-parameter in the Auger spectrum for carbon, it is possible to distinguish between general crystalline graphene, nanocrystalline graphene, and amorphous carbon layers. Furthermore, the hydrogen content described below can be obtained, for example, through component analysis using RBS (Rutherford Backscattering Spectroscopy).

[0062] Typical crystalline graphene, also known as intrinsic graphene, can contain crystals larger than, for example, approximately 100 nm. In typical crystalline graphene, the D-parameter in the Auger spectrum for carbon can be approximately 23 eV. In this case, sp² for the entire carbon 2 The proportion of carbon having a bonding structure can be nearly 100%. Such typical crystalline graphene may contain almost no hydrogen. Also, typical crystalline graphene can have a density of, for example, approximately 2.1 g / cc, and a sheet resistance of, for example, approximately 100 to 300 Ohm / sq.

[0063] In contrast, the nanocrystalline graphene may contain crystals (i.e., grains) smaller in size than conventional crystalline graphene. For example, nanocrystalline graphene may contain grains having a grain size of approximately 0.5 nm to 100 nm. Specifically, nanocrystalline graphene may contain grains having a grain size of approximately 0.5 nm to 50 nm. High grain density can be provided within this range. In such nanocrystalline graphene, the D-parameter in the Auger spectrum for carbon may be approximately 18 to 22.9 eV. In this case, sp² for the total carbon 2 The proportion of carbon having a bonded structure can be, for example, approximately 50% to 99%. Nanocrystalline graphene can contain, for example, approximately 1 to 20 at% (atomic percent) of hydrogen. In addition, nanocrystalline graphene can have a density of, for example, approximately 1.6 to 2.1 g / cc, and a sheet resistance of, for example, greater than approximately 1000 Ohm / sq.

[0064] The above nanocrystalline graphene may have a Raman spectrum D / G peak ratio of 1.0 or higher and a 2D / G peak ratio of 0.1 or higher. Highly crystalline graphene can be provided within the above range.

[0065] The above nanocrystalline graphene may be graphene-on-substrate formed on a non-catalytic substrate. The thickness of the graphene-on-substrate ranges from 1 to 100 Å, and the non-uniformity region is 10% or less, with a thickness of 1x1 cm 2 It can have an area greater than or equal to the above. A large-area uniform nanocrystalline graphene can be provided within the above range.

[0066] The above non-catalytic substrate may be made of a material having a bulk solubility of carbon atoms in the range of 0.1 or less at a temperature of 1000°C or lower. For example, the above non-catalytic substrate may include at least one of a group IV semiconductor material, a semiconductor compound, a metal, and an insulating material.

[0067] As a specific example, group IV semiconductor materials may include Si, Ge, or Sn.

[0068] Semiconductor compounds may include, for example, materials in which at least two elements from Si, Ge, C, Zn, Cd, Al, Ga, In, B, C, N, P, S, Se, As, Sb, and Te are combined.

[0069] The metal may include, for example, at least one of Cu, Mo, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, and Gd.

[0070] The insulating material may include, for example, at least one of Si, Al, Hf, Zr, Zn, Ti, Ta, W, and Mn, or at least one of oxides, nitrides, carbides, and derivatives thereof selected from at least one of Si, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, Cu, Mo, and Gd. At least one of the oxides, nitrides, carbides, and derivatives thereof may further include H.

[0071] Meanwhile, the non-catalytic substrate may further include a dopant. The substrate materials mentioned above are merely exemplary, and the substrate may include various other materials.

[0072] The graphene on the substrate may further include a metal layer on the nanocrystalline graphene. Since the nanocrystalline graphene has high coverage and can be grown directly over a large area, including a metal layer thereon can provide a metal layer / graphene / substrate structure requiring low resistance.

[0073] The graphene on the substrate further comprising a metal layer on the nanocrystalline graphene can have its resistance improved by limiting diffusion between the metal layer (e.g., W) and the substrate (e.g., Si) by the completely covered nanocrystalline graphene. Since the nanocrystalline graphene has low surface roughness, the surface roughness of the metal layer deposited thereon can also be improved.

[0074] Fig. 13a shows 430 ea / um 2 Figure 13b is an AFM image of graphene on a substrate having a low grain density, and is an AFM image of tungsten (W) deposited on the graphene on the substrate.

[0075] As shown in Figures 13a and 13b, when tungsten (W) was deposited on graphene on a substrate with low grain density, the surface roughness (RMS) was found to be 0.91 nm and the resistance (Rs) was found to be > 15 Ω / sq.

[0076] Fig. 14a shows 1100 ea / um 2 Figure 14b is an AFM image of graphene on a substrate having a high grain density, and is an AFM image of tungsten (W) deposited on the graphene on the substrate.

[0077] As shown in Figures 14a and 14b, when tungsten (W) was deposited on graphene on a substrate with high grain density, the surface roughness (RMS) was found to be 0.59 nm and the resistance (Rs) was found to be 5.52 Ω / sq.

[0078] The above nanocrystalline graphene may be grown directly on a non-catalyst substrate by a plasma chemical vapor deposition process at a temperature of 700°C or lower using a plasma of a reaction gas containing a carbon source and an inert gas.

[0079] A method for manufacturing nanocrystalline graphene according to one embodiment is described below.

[0080] A method for manufacturing nanocrystalline graphene according to one embodiment is,

[0081] A step of injecting a reaction gas containing a carbon source gas and an inert gas into a reaction chamber;

[0082] A step of generating a plasma of the reaction gas within the reaction chamber; and

[0083] A step of forming nanocrystalline graphene by directly growing it on a non-catalytic substrate using a plasma of the reaction gas at a temperature of 700℃ or lower;

[0084] Includes

[0085] A reaction gas for the growth of nanocrystalline graphene is injected into a reaction chamber equipped with a non-catalytic substrate, and then power is applied to generate plasma.

[0086] Specifically, first, a substrate for growing nanocrystalline graphene is prepared inside a reaction chamber. Various types of substrates can be used as the substrate for growing nanocrystalline graphene, for example, it may be a non-catalytic substrate made of a material having a bulk solubility of carbon atoms in the range of 0.1 or less at a temperature of 1000°C or lower.

[0087] For example, the substrate may include at least one of a group IV semiconductor material, a semiconductor compound, a metal, and an insulating material. As a specific example, the group IV semiconductor material may include Si, Ge, or Sn. And, the semiconductor compound may include, for example, a material in which at least two elements are combined from Si, Ge, C, Zn, Cd, Al, Ga, In, B, C, N, P, S, Se, As, Sb, and Te.

[0088] The metal may include, for example, at least one of Cu, Mo, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, and Gd. The insulating material may include at least one of Si, Al, Hf, Zr, Zn, Ti, Ta, W, and Mn, or at least one of an oxide, nitride, carbide, and derivative thereof selected from Si, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, Cu, Mo, and Gd. At least one of the oxide, nitride, carbide, and derivative thereof may further include H. Meanwhile, the substrate may further include a dopant. The materials of the substrate mentioned above are merely exemplary, and the substrate may include various other materials.

[0089] Next, a reaction gas for the growth of nanocrystalline graphene is injected into the reaction chamber. The reaction gas may include a carbon source, an inert gas, and hydrogen gas. Meanwhile, the reaction gas may not include hydrogen gas. For example, the reaction gas may include a carbon source, an inert gas, and hydrogen gas.

[0090] The carbon source can be a source that supplies carbon for the growth of nanocrystalline graphene. For example, the carbon source may include at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon.

[0091] Hydrocarbon gases may include, for example, methane gas, ethylene gas, acetylene gas, or propylene gas, but this is merely illustrative and may include gases of various other substances.

[0092] And, the liquid precursor is C x H y Aromatic hydrocarbons having the chemical formula (6≤x≤42, 6≤y≤28) and their derivatives, and C x H y It may include at least one of an aliphatic hydrocarbon having the chemical formula (1≤x≤12, 2≤y≤26) and its derivatives. Here, the aromatic hydrocarbon may include, for example, benzene, toluene, xylene, or anisol, and the aliphatic hydrocarbon may include, for example, hexane, octane, isopropyl alcohol, or ethanol. However, this is merely illustrative.

[0093] The inert gas may include, for example, at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas, and xenon gas. FIG. 1a illustrates an exemplary case where acetylene gas is used as the carbon source and argon gas is used as the inert gas.

[0094] The flow rate of the inert gas may be in the range of 600 to 1600 sccm. In this range, nanocrystalline graphene with high grain density and low surface roughness can be grown.

[0095] Next, power for generating plasma is applied from a plasma power source into the reaction chamber. Here, the power for generating plasma can be approximately 10W to 4000W. However, it is not limited to this.

[0096] For example, an RF (Radio Frequency) plasma generator or a MW (Microwave) plasma generator may be used as the plasma power source. Here, to grow nanocrystalline graphene, the RF plasma generator may generate RF plasma having a frequency range of, for example, approximately 3 to 100 MHz, and the MW plasma generator may generate MW plasma having a frequency range of, for example, approximately 0.7 to 2.5 GHz. However, these frequency ranges are merely exemplary, and other frequency ranges may also be used. Meanwhile, multiple RF plasma generators or multiple MW plasma generators may be used as the plasma power source.

[0097] When power for generating plasma is applied from a plasma power source into the reaction chamber, an electric field can be induced inside the reaction chamber. When an electric field is induced in this way while the reaction gas is injected, a plasma for the growth of nanocrystalline graphene is formed.

[0098] When growing nanocrystalline graphene using plasma, the mixing ratio of the reaction gas injected into the reaction chamber, that is, the volume ratio of the carbon source, inert gas, and hydrogen gas, can be, for example, approximately 1:0.01 to 5000:0 to 300. Here, the volume ratio of the carbon source, inert gas, and hydrogen gas included in the reaction gas can be appropriately adjusted according to other growth conditions.

[0099] The process temperature for growing nanocrystalline graphene can be approximately 700°C or lower, which is lower than the temperature used in general chemical vapor deposition processes. Specifically, the process temperature inside the reaction chamber can be approximately 180°C to 700°C. Also, the process pressure for growing nanocrystalline graphene can be approximately 0.001 Torr to 10 Torr. However, this is merely an example, and other process pressures may be used.

[0100] Active carbon radicals (C·) are generated by a plasma of a reaction gas mixture comprising a carbon source, an inert gas, and hydrogen gas, and are adsorbed onto the surface of a substrate. Specifically, the plasma of the inert gas among the reaction gases generates active carbon radicals (C·) from the carbon source gas, and the surface of the substrate is activated by the adsorption of these generated active carbon radicals (C·) onto the substrate surface. Furthermore, as the plasma of the inert gas continuously induces the activation of the substrate, the adsorption of active carbon radicals (C·) onto the surface of the substrate can be accelerated.

[0101] As the adsorption of activated carbon radicals (C·) on the surface of the substrate is accelerated, nanocrystalline graphene can be grown and formed on the surface of the substrate in a short period of time.

[0102] Accordingly, nanocrystalline graphene can be grown at a relatively fast rate on the surface of a substrate. For example, nanocrystalline graphene can be grown on the surface of a substrate to a thickness of 0.05 nm or more per minute. However, it is not limited to this. Accordingly, nanocrystalline graphene can be grown to a desired thickness in a relatively short period of time. For example, the time required for growing nanocrystalline graphene on the surface of a substrate can be, for instance, 60 minutes or less. More specifically, the time required for growing nanocrystalline graphene can be 30 minutes or less or 10 minutes or less. However, it is not limited to this. In this way, nanocrystalline graphene of a desired thickness can be directly formed on the surface of a substrate in a relatively short period of time due to an inert gas plasma. Such nanocrystalline graphene can have a single-layer or multi-layer structure.

[0103] According to the present embodiment, in a plasma chemical vapor deposition process, the reaction gas includes a carbon source, an inert gas, and a hydrogen gas, and by activating the surface of the substrate by the plasma of the inert gas, nanocrystalline graphene can be directly grown and formed on the surface of the substrate in a relatively short time even at a relatively low temperature of 700°C or lower.

[0104] A method for forming nanocrystalline graphene according to another exemplary embodiment is described.

[0105] According to another embodiment, a pretreatment process can be performed on the surface of a substrate using a reducing gas before growing nanocrystalline graphene. Here, the pretreatment process of the substrate can be performed for the purpose of removing impurities or oxygen remaining on the surface of the substrate.

[0106] To explain in detail, first, a substrate for growing nanocrystalline graphene is prepared inside a reaction chamber. Here, the substrate may include various materials as described above.

[0107] Next, a gas for pretreatment of the substrate is injected into the reaction chamber. A reducing gas may be used as the gas for this pretreatment. Here, the reducing gas may include, for example, at least one of hydrogen, nitrogen, chlorine, fluorine, ammonia, and derivatives thereof. However, it is not limited thereto. Additionally, an inert gas may be injected into the reaction chamber in addition to the reducing gas. Here, the inert gas may include, for example, at least one of argon gas, neon gas, helium gas, krypton gas, and xenon gas. For example, hydrogen gas may be used as the reducing gas, and argon gas may be used as the inert gas.

[0108] Next, power for generating plasma is applied from a plasma power source into the reaction chamber. Here, the power for generating plasma can be approximately 10W to 4000W, but is not limited thereto. For example, at least one RF plasma generator or at least one MW plasma generator may be used as the plasma power source.

[0109] When power for generating plasma is applied from a plasma power source to the reaction chamber, an electric field can be induced inside the reaction chamber. In this way, when an electric field is induced while a reducing gas (or a mixture of a reducing gas and an inert gas) is injected, a plasma for the pretreatment of a substrate is formed. The surface of the substrate can be treated by the plasma formed in this manner. Meanwhile, this pretreatment process of the substrate may be carried out while a predetermined voltage is applied to the substrate. However, it is not limited to this, and voltage may not be applied to the substrate. Accordingly, impurities or oxygen remaining on the surface of the substrate can be removed. Once this pretreatment process of the substrate is completed, gases or impurities remaining inside the reaction chamber can be discharged to the outside of the reaction chamber.

[0110] After the pretreatment process of the substrate is completed, a reaction gas for the growth of nanocrystalline graphene is injected into the reaction chamber, and then power is applied to the inside of the reaction chamber to generate plasma.

[0111] To explain in detail, first, a reaction gas for the growth of nanocrystalline graphene is injected into the reaction chamber. The reaction gas may include a carbon source gas, an inert gas, and hydrogen gas. Meanwhile, this reaction gas may not include hydrogen gas. For example, the reaction gas may include a carbon source, an inert gas, and hydrogen gas.

[0112] The carbon source may include, for example, at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon. The hydrocarbon gas may include, for example, methane gas, ethylene gas, acetylene gas, or propylene gas, but this is merely exemplary.

[0113] The liquid precursor is, for example, C x H y Aromatic hydrocarbons having the chemical formula (6≤x≤42, 6≤y≤28) and their derivatives, and C x H y It may include at least one of an aliphatic hydrocarbon having the chemical formula (1≤x≤12, 2≤y≤26) and its derivatives. Here, the aromatic hydrocarbon may include, for example, benzene, toluene, xylene, or anisol, and the aliphatic hydrocarbon may include, for example, hexane, octane, isopropyl alcohol, or ethanol. However, this is merely illustrative.

[0114] The inert gas may include, for example, at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas, and xenon gas. FIG. 6b illustrates an exemplary case where acetylene gas is used as the carbon source and argon gas is used as the inert gas.

[0115] Next, power for generating plasma is applied from a plasma power source into the reaction chamber. Here, the power for generating plasma can be approximately 10W to 4000W. For example, at least one RF plasma generator or at least one MW plasma generator may be used as the plasma power source. Here, the RF plasma generator can generate RF plasma having a frequency range of approximately 3 to 100 MHz, for example, and the MW plasma generator can generate MW plasma having a frequency range of approximately 0.7 to 2.5 GHz, for example. However, it is not limited thereto. When power for generating plasma is applied from the plasma power source into the reaction chamber, an electric field can be induced inside the reaction chamber. When an electric field is induced in this state with the reaction gas injected, a plasma for the growth of nanocrystalline graphene is formed.

[0116] When growing nanocrystalline graphene using plasma, the mixing ratio of the reaction gas injected into the reaction chamber, specifically the volume ratio of the carbon source, inert gas, and hydrogen gas, can be, for example, approximately 1:0.01 to 5000:0 to 300. Here, the volume ratio of the carbon source, inert gas, and hydrogen gas included in the reaction gas can be appropriately adjusted according to other growth conditions.

[0117] The process temperature can be approximately 180°C to 700°C, and the process pressure can be approximately 0.001 Torr to 10 Torr. However, this is merely an example, and other process temperatures or process pressures may also be used.

[0118] As described above, when an electric field is induced while a reaction gas is injected, a plasma for the growth of nanocrystalline graphene is formed. Among these reaction gases, the plasma of an inert gas generates activated carbon radicals from a carbon source, and these generated activated carbon radicals are adsorbed onto the surface of the substrate, thereby activating the substrate surface. Furthermore, as the plasma of the inert gas continuously induces the activation of the substrate, the adsorption of activated carbon radicals onto the surface of the substrate can be accelerated.

[0119] As described above, as activated carbon radicals are accelerated on the surface of the substrate, nanocrystalline graphene can be grown and formed on the surface of the substrate in a short period of time.

[0120] Nanocrystalline graphene can be grown at a relatively fast rate on the surface of a substrate. For example, nanocrystalline graphene can be grown on the surface of a substrate to a thickness of 0.05 nm or more per minute, but is not limited thereto. Accordingly, nanocrystalline graphene can be grown to a desired thickness in a relatively short time, for example, 60 minutes or less (more specifically, 30 minutes or less or 10 minutes or less). In this way, nanocrystalline graphene can be formed on the surface of a substrate to a desired thickness in a relatively short time. The nanocrystalline graphene formed in this way can have a single-layer or multi-layer structure.

[0121] According to the present embodiment, relatively high-quality nanocrystalline graphene can be obtained by pre-treating the surface of a substrate using a reducing gas (or a mixture of a reducing gas and an inert gas) and then growing and forming nanocrystalline graphene on the surface of the pre-treated substrate.

[0122] A method for forming nanocrystalline graphene according to another exemplary embodiment is described.

[0123] According to another embodiment, a primary reaction gas is injected into the reaction chamber in which the substrate is provided, and then power is applied to generate plasma. Meanwhile, a pretreatment process of the substrate may be performed before injecting the primary reaction gas.

[0124] Specifically, first, a substrate is prepared inside a reaction chamber. As previously mentioned, the substrate may comprise, for example, at least one of a Group IV semiconductor material, a semiconductor compound, a metal, and an insulating material. The substrate may further comprise a dopant. However, this is merely illustrative.

[0125] Next, a primary reaction gas is injected into the reaction chamber. Here, the primary reaction gas may be a reaction gas for the growth of the first nanocrystalline graphene described later. For example, the primary reaction gas may include a carbon source, an inert gas, and a hydrogen gas. Meanwhile, the primary reaction gas may not include hydrogen gas. The reaction gas may include a carbon source, an inert gas, and a hydrogen gas.

[0126] The carbon source may include, for example, at least one of a hydrocarbon gas and the vapor of a liquid precursor containing carbon. Here, the hydrocarbon gas may include, for example, methane gas, ethylene gas, acetylene gas, or propylene gas. Additionally, the liquid precursor is C x H y Aromatic hydrocarbons having the chemical formula (6≤x≤42, 6≤y≤28) and their derivatives, and C x H y It may include at least one of an aliphatic hydrocarbon having the chemical formula (1≤x≤12, 2≤y≤26) and its derivatives.

[0127] The inert gas may include, for example, at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas, and xenon gas. For example, acetylene gas may be used as a carbon source, and argon gas may be used as an inert gas.

[0128] Next, power for generating plasma is applied from a plasma power source into the reaction chamber. Here, the power for generating plasma can be approximately 10W to 4000W. For example, at least one RF plasma generator or at least one MW plasma generator may be used as the plasma power source. Here, the RF plasma generator can generate RF plasma having a frequency range of approximately 3 to 100 MHz, for example, and the MW plasma generator can generate MW plasma having a frequency range of approximately 0.7 to 2.5 GHz, for example. However, it is not limited thereto.

[0129] When power for generating plasma is applied from a plasma power source into the reaction chamber, an electric field can be induced inside the reaction chamber. In this way, when an electric field is induced while the primary reaction gas is injected, a plasma for the growth of the first nanocrystalline graphene is formed.

[0130] When growing the first nanocrystalline graphene using plasma, the mixing ratio of the primary reaction gases, that is, the volume ratio of the carbon source, inert gas, and hydrogen gas, can be, for example, approximately 1:0.01 to 5000:0 to 300.

[0131] For example, the volume ratios of the carbon source, inert gas, and hydrogen gas included in the primary reaction gas can be adjusted to further activate the surface of the substrate and increase the nucleation density. The process temperature can be approximately 180°C to 700°C, and the process pressure can be approximately 0.01 Torr to 10 Torr. However, it is not limited to these values.

[0132] As described above, when an electric field is induced while a primary reaction gas is injected, a plasma for the growth of the first nanocrystalline graphene is formed. Then, the plasma of the inert gas among the primary reaction gases generates activated carbon radicals from the carbon source gas, and the surface of the substrate is activated by the adsorption of these generated activated carbon radicals onto the surface of the substrate. By continuously inducing the activation of the substrate with this inert gas plasma, the adsorption of activated carbon radicals can be accelerated.

[0133] A first nanocrystalline graphene can be grown and formed on the surface of the substrate by continuously adsorbing activated carbon radicals onto the surface of the substrate. This first nanocrystalline graphene can be grown on the surface of the substrate at a relatively fast rate within a short period of time. This first nanocrystalline graphene can have a single-layer or multi-layer structure. After the formation of this first nanocrystalline graphene is complete, the gas remaining in the reaction chamber can be discharged to the outside of the reaction chamber.

[0134] As described above, after forming the first nanocrystalline graphene on the surface of the substrate, a secondary reaction gas is injected into the reaction chamber to form the second nanocrystalline graphene, and then power is applied to generate plasma.

[0135] Specifically, a secondary reaction gas is first injected into the reaction chamber. Here, the secondary reaction gas may be a reaction gas for the growth of the second nanocrystalline graphene described later. This secondary reaction gas may include a carbon source, an inert gas, and a hydrogen gas, similar to the primary reaction gas described above. Meanwhile, the secondary reaction gas may not include hydrogen gas.

[0136] As described above, the carbon source may include, for example, at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon. And, the inert gas may include, for example, at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas, and xenon gas. For example, acetylene gas may be used as the carbon source and argon gas may be used as the inert gas.

[0137] Next, power for generating plasma is applied from a plasma power source into the reaction chamber. Here, the power for generating plasma can be approximately 10W to 4000W. As previously mentioned, at least one RF plasma generator or at least one MW plasma generator may be used as the plasma power source. When power for generating plasma is applied from the plasma power source into the reaction chamber, an electric field can be induced inside the reaction chamber. In this way, when an electric field is induced while a secondary reaction gas is injected, a plasma for the growth of the second nanocrystalline graphene is formed.

[0138] When growing a second nanocrystalline graphene using plasma, the mixing ratio of the secondary reaction gas, that is, the volume ratio of the carbon source, inert gas, and hydrogen gas, can be, for example, approximately 1:0.01 to 5000:0 to 300.

[0139] The mixing ratio of the carbon source, inert gas, and hydrogen gas included in the secondary reaction gas can be controlled differently from the primary reaction gas. For example, the mixing ratio of the carbon source, inert gas, and hydrogen gas included in the secondary reaction gas can be controlled so that the second nanocrystalline graphene can grow more uniformly than the first nanocrystalline graphene.

[0140] The process temperature can be approximately 180°C to 700°C, and the process pressure can be approximately 0.001 Torr to 10 Torr. However, it is not limited to these values.

[0141] As described above, when an electric field is induced while a secondary reaction gas is injected, a plasma for the growth of the second nanocrystalline graphene is formed. Then, the plasma of the inert gas among the secondary reaction gases generates activated carbon radicals from the carbon source gas, and the activated carbon radicals thus generated can be continuously adsorbed onto the surface of the first nanocrystalline graphene formed on the substrate.

[0142] As activated carbon radicals are continuously adsorbed onto the surface of the first nanocrystalline graphene, a second nanocrystalline graphene can be grown and formed on the surface of the first nanocrystalline graphene. Here, the second nanocrystalline graphene can be grown and formed more uniformly than the first nanocrystalline graphene by controlling the mixing ratio of the carbon source, inert gas, and hydrogen gas. This second nanocrystalline graphene can be grown to a desired thickness within a short period of time at a relatively fast speed on the surface of the first nanocrystalline graphene. This second nanocrystalline graphene can have a single-layer or multi-layer structure.

[0143] According to the present embodiment, different first and second nanocrystalline graphenes can be sequentially formed on the surface of a substrate by performing the growth process of nanocrystalline graphene in two stages by adjusting the mixing ratio of the carbon source, inert gas, and hydrogen gas. Meanwhile, the above description exemplarily describes a case in which two different nanocrystalline graphenes are grown and formed on a substrate by performing the growth process twice with different mixing ratios of the carbon source, inert gas, and hydrogen gas. However, the present embodiment is not limited thereto, and three or more different nanocrystalline graphenes can be grown and formed on a substrate by performing the growth process as described above three or more times.

[0144] According to the above embodiments, in a plasma chemical vapor deposition process, the reaction gas includes a carbon source, an inert gas, and a hydrogen gas, and by activating the surface of the substrate with a plasma of the inert gas, nanocrystalline graphene can be directly grown and formed on the surface of the substrate in a relatively short time even at a relatively low temperature of 700°C or lower.

[0145] In addition, higher quality nanocrystalline graphene can be obtained through a substrate pretreatment process, and multiple different nanocrystalline graphenes can be formed on the substrate by performing the nanocrystalline graphene growth process multiple times with different mixing ratios of carbon source, inert gas, and hydrogen gas.

[0146] Since the technology for directly growing and forming nanocrystalline graphene on the surface of a substrate at a relatively low temperature can be applied in CMOS (Complementary Metal-Oxide-Semiconductor) processes, it can be applied to form elements of semiconductor devices such as barrier metals or source / drain contacts, or to manufacture pellicles for photolithography equipment.

Claims

Claim 1 It includes a plurality of grains formed by stacking a plurality of graphene sheets, and 500 ea / um 2 Nanocrystalline graphene having a grain density greater than or equal to 0.1 and a root mean square (RMS) surface roughness greater than or equal to 1.

0. Claim 2 In claim 1, the nanocrystalline graphene is nanocrystalline graphene having a thickness of 10 nm or less. Claim 3 In paragraph 2, the nanocrystalline graphene is nanocrystalline graphene having a thickness of 2 nm or less. Claim 4 In claim 1, the grain is nanocrystalline graphene having a grain size of 0.5 nm to 50 nm. Claim 5 In claim 1, the nanocrystalline graphene is a nanocrystalline graphene having a D / G peak ratio of 1.0 or higher and a 2D / G peak ratio of 0.1 or higher. Claim 6 In claim 5, the nanocrystalline graphene is a substrate-based graphene formed on a non-catalytic substrate. Claim 7 In claim 6, the thickness of the graphene on the substrate is 1 to 100 1x1 cm with a range and a non-uniformity area of ​​10% or less 2 Nanocrystalline graphene having an area greater than or equal to that. Claim 8 In claim 6, the non-catalytic substrate is nanocrystalline graphene made of a material having a bulk solubility of carbon atoms in the range of 0.1 or less at a temperature of 1000°C or lower. Claim 9 In claim 6, the non-catalytic substrate is nanocrystalline graphene comprising at least one of a group IV semiconductor material, a semiconductor compound, a metal, and an insulating material. Claim 10 In claim 9, the group IV semiconductor material comprises Si, Ge, or Sn; the semiconductor compound comprises a material in which at least two elements selected from Si, Ge, C, Zn, Cd, Al, Ga, In, B, C, N, P, S, Se, As, Sb, and Te are combined; the metal comprises at least one selected from Cu, Mo, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, and Gd; and the insulating material comprises at least one selected from Si, Al, Hf, Zr, Zn, Ti, Ta, W, and Mn, or at least one selected from the oxides, nitrides, carbides, and derivatives thereof selected from Si, Ni, Al, W, Ru, Co, Mn, Ti, Ta, Au, Hf, Zr, Zn, Y, Cr, Cu, Mo, and Gd, nanocrystalline graphene. Claim 11 In claim 6, the graphene on the substrate is nanocrystalline graphene that further comprises a metal layer on the nanocrystalline graphene. Claim 12 In claim 1, the nanocrystalline graphene is nanocrystalline graphene grown directly on a non-catalyst substrate by a plasma chemical vapor deposition process at a temperature of 700°C or lower using a plasma of a reaction gas containing a carbon source and an inert gas. Claim 13 A method for manufacturing nanocrystalline graphene according to claim 1, comprising: a step of injecting a reaction gas including a carbon source gas and an inert gas into a reaction chamber; a step of generating a plasma of the reaction gas within the reaction chamber; and a step of directly growing and forming nanocrystalline graphene on a non-catalytic substrate using the plasma of the reaction gas at a temperature of 700°C or lower, wherein the flow rate of the inert gas is in the range of 600 to 1600 sccm. Claim 14 delete Claim 15 A method for producing nanocrystalline graphene according to claim 13, wherein the reaction gas does not contain hydrogen gas or further contains hydrogen gas. Claim 16 A method for producing nanocrystalline graphene according to claim 15, wherein the reaction gas further includes hydrogen gas, and the volume ratio of the carbon source, inert gas, and hydrogen gas is 1: 0.01 to 5000: 0 to 300. Claim 17 A method for producing nanocrystalline graphene according to claim 13, wherein the carbon source comprises at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon. Claim 18 A method for producing nanocrystalline graphene according to claim 13, wherein the inert gas comprises at least one of argon gas, neon gas, nitrogen gas, helium gas, krypton gas and xenon gas. Claim 19 In claim 13, the nanocrystalline graphene is a method for manufacturing nanocrystalline graphene grown at a process temperature of 180°C to 700°C. Claim 20 In claim 13, the nanocrystalline graphene is a method for producing nanocrystalline graphene grown at a process pressure of 0.001 Torr to 10 Torr. Claim 21 A method for manufacturing nanocrystalline graphene according to claim 13, wherein the plasma is generated by at least one RF (Radio Frequency) plasma generator or at least one MW (Microwave) plasma generator. Claim 22 A method for manufacturing nanocrystalline graphene according to claim 13, wherein the plasma comprises an RF plasma having a frequency range of 3 to 100 MHz or an MW plasma having a frequency range of 0.7 to 2.5 GHz. Claim 23 A method for manufacturing nanocrystalline graphene according to claim 13, wherein the power for generating the plasma of the reaction gas is 10W to 4000W. Claim 24 A method for manufacturing nanocrystalline graphene according to claim 13, further comprising the step of pretreating the surface of the substrate using a reducing gas before growing the nanocrystalline graphene. Claim 25 A method for manufacturing nanocrystalline graphene according to claim 13, further comprising the step of first forming the nanocrystalline graphene on the substrate, and then secondarily forming additional nanocrystalline graphene on the nanocrystalline graphene by adjusting the mixing ratio of the reaction gas.

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