Method for forming nanocrystalline graphene

Abstract

A method for forming nanocrystalline graphene according to one example comprises the steps of: placing a substrate having a predetermined pattern in a reaction chamber; injecting a reaction gas mixed with a carbon source gas, an inert gas, and a hydrogen gas into the reaction chamber; generating a plasma of the reaction gas in the reaction chamber; and directly growing the nanocrystalline graphene on the surface of the pattern using the plasma of the reaction gas at a predetermined process temperature, wherein the pattern comprises a first material and the substrate may comprise a second material different from the first material.

Description

Technology Field

[0001] The present invention relates to a method for forming nanocrystalline graphene, and more specifically, to a method for forming nanocrystalline graphene by selectively growing it on a substrate having a predetermined pattern using a plasma chemical vapor deposition method. Background Technology

[0002] Recently, there has been a trend toward shrinking the size of semiconductor devices to achieve high integration. To facilitate this, it is necessary to reduce the linewidth of conductive wiring composed of metals or metal alloys within interconnect structures. However, as the linewidth of conductive wiring decreases, the current density within the wiring increases, resulting in higher resistance. This increase in resistance can induce electromigration of the metal or metal alloy atoms constituting the wiring, potentially leading to defects within the wiring. Therefore, it is necessary to provide a capping layer to lower the resistance of the conductive wiring.

[0003] Nanocrystalline graphene can be selectively disposed on the cap layer to lower the resistance of conductive wiring. Graphene is a crystalline material in which carbon atoms are connected two-dimensionally to form a hexagonal honeycomb structure, possessing an extremely thin thickness at the atomic level. Such graphene can be synthesized by Chemical Vapor Deposition (CVD) or obtained by peeling off graphite layer by layer. Graphene generally contains crystals with a size at the micrometer level. Meanwhile, nanocrystalline graphene refers to graphene containing crystals with a size at the nano level. The problem to be solved

[0004] An exemplary embodiment provides a method for selectively growing nanocrystalline graphene on a substrate having a predetermined pattern using a plasma chemical vapor deposition method. means of solving the problem

[0005] A method for forming nanocrystalline graphene according to one example comprises the steps of: placing a substrate having a predetermined pattern in a reaction chamber; injecting a reaction gas mixed with a carbon source gas, an inert gas, and a hydrogen gas into the reaction chamber; generating a plasma of the reaction gas in the reaction chamber; and directly growing the nanocrystalline graphene on the surface of the pattern using the plasma of the reaction gas at a predetermined process temperature, wherein the pattern comprises a first material and the substrate may comprise a second material different from the first material.

[0006] The first material may include one or more metals or metal alloys selected from Cu, Ru, Rh, Ir, Mo, W, Pd, Pt, Co, Ta, and Ti.

[0007] The second material above may include a dielectric material having a dielectric constant of 3.6 or less.

[0008] When growing the nanocrystalline graphene using the above plasma, the volume ratio of the hydrogen gas to the inert gas may be 5:100 to 100:1.

[0009] The plasma of the above reaction gas may include RF (Radio Frequency) plasma or MW (Microwave) plasma.

[0010] The above plasma may include an RF plasma having a frequency range of 3 to 100 MHz or an MW plasma having a frequency range of 0.7 GHz to 2.5 GHz.

[0011] The power for generating the plasma of the above reaction gas can be 10W to 1500W.

[0012] The above nanocrystalline graphene can be grown at a process temperature of 550 degrees or lower.

[0013] The above nanocrystalline graphene can be grown at a process pressure of 0.005 Torr to 10 Torr.

[0014] The carbon source gas may include at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon.

[0015] The above 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.

[0016] The above inert gas may include at least one of argon gas, nitrogen gas, helium gas, krypton gas, and xenon gas.

[0017] The above nanocrystalline graphene may include crystals with a size of 0.5 nm to 150 nm.

[0018] The above nanocrystalline graphene is sp relative to the total carbon. 2 The proportion of carbon having a bonding structure can be 50% to 99%.

[0019] The above predetermined pattern can be placed in a trench shape provided on the substrate.

[0020] The above nanocrystalline graphene may contain 1 to 20 at% (atomic percent) of hydrogen.

[0021] The above nanocrystalline graphene can have a density of 1.6 to 2.1 g / cc.

[0022] The method may further include a step of pretreating the surface of the substrate using a reducing gas injected into the reaction chamber before growing the nanocrystalline graphene.

[0023] The above reducing gas may include at least one of hydrogen, nitrogen, chlorine, fluorine, ammonia, and derivatives thereof.

[0024] Inert gas may be further injected into the above reaction chamber. Effects of the invention

[0025] According to an exemplary embodiment, in a plasma chemical vapor deposition process, a mixed gas of carbon source gas, inert gas, and hydrogen gas is used as the reaction gas, and by activating the surface of the substrate by the plasma of the inert gas among the mixed gas, nanocrystalline graphene can be directly grown and formed on the surface of the substrate in a relatively short time without a catalyst, even at a relatively low temperature of 550 degrees or less.

[0026] In addition, nanocrystalline graphene can be selectively grown only in specific patterns included in the substrate by varying the ratios of carbon source gas, inert gas, and hydrogen gas. Therefore, nanocrystalline graphene can be selectively grown depending on the structure of the substrate having patterns containing different materials, and accordingly, nanocrystalline graphene can be formed only in desired areas of the substrate.

[0027] In addition, higher quality nanocrystalline graphene can be obtained through a substrate pretreatment process. Brief explanation of the drawing

[0028] FIG. 1a is a perspective view of an interconnect structure according to one example. FIG. 1b is a cross-sectional view of the interconnect structure shown in FIG. 1a, cut along the line A-A'. FIGS. 2a to 2d are drawings illustrating a method for forming nanocrystalline graphene according to an exemplary embodiment. FIG. 3a shows Raman spectra showing whether nanocrystalline graphene was grown in a short time on a predetermined pattern according to an example. FIG. 3b shows Raman spectra showing whether nanocrystalline graphene was grown on a substrate in a short period of time according to an example. Figure 4 is a TEM (Transmission Electron Microscope) image showing nanocrystalline graphene grown on a copper pattern by RF (Radio Frequency) plasma according to an exemplary embodiment. FIGS. 5a and 5b are drawings illustrating a method for forming nanocrystalline graphene according to a comparative example. Figure 6 shows Raman spectra showing whether nanocrystalline graphene was grown in a short time on a predetermined pattern and substrate according to an embodiment. FIGS. 7a and 7b are drawings illustrating a method for forming nanocrystalline graphene according to a comparative example. Figure 8 is a graph showing the uniformity of nanocrystalline graphene according to the example and comparative example. FIGS. 9a to 9e are drawings illustrating a method for forming nanocrystalline graphene according to an exemplary embodiment. Specific details for implementing the invention

[0029] Hereinafter, exemplary embodiments will be described in detail with reference to the attached drawings. In the drawings below, the same reference numerals denote the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of explanation. The embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

[0030] Meanwhile, as described below, terms referred to as "upper" or "upper" may include not only those directly above in contact but also those above non-contact. Singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. The use of the term "above" and similar descriptive terms may apply to both singular and plural forms.

[0031] In the following examples, a method for growing and forming nanocrystalline graphene on the surface of a substrate in a short time using a Plasma Enhanced Chemical Vapor Deposition (PECVD) method is described. Here, nanocrystalline graphene refers to graphene containing crystals having a size at the nano level. While general graphene contains crystals having a size at the micrometer level, nanocrystalline graphene may contain crystals at the nanometer level, for example, approximately 0.5 nm to 150 nm in size.

[0032] FIG. 1a is a perspective view of an interconnect structure according to one example. FIG. 1b is a cross-sectional view of the interconnect structure shown in FIG. 1a cut along the line A-A'.

[0033] Referring to FIGS. 1a and 1b, an interconnect structure (1) according to one example may include a capping layer (10), a dielectric layer (20), and a conductive wire (30). In one example, the capping layer (10) may be placed on the upper surface of the conductive wire (30) to reduce the electrical resistance of the conductive wire (30), thereby improving the resistance to electromigration. In one example, the capping layer (10) may include nanocrystalline graphene. In one example, when a capping layer (10) made of nanocrystalline graphene is placed on the upper surface of a conductive wire (30) made of copper wire, the electrical resistance of the conductive wire (30) may be reduced by approximately 4% or more compared to the case where the capping layer (10) is not formed on the upper surface of the conductive wire (30).

[0034] The dielectric layer (20) may have a single layer or a multilayer structure in which different materials are stacked. According to one example, the dielectric layer (20) may include a dielectric material used in a general semiconductor manufacturing process. With the miniaturization of semiconductor devices, the parasitic capacitance of the dielectric layer (20) can be an important factor in improving the performance of the wiring. Accordingly, the dielectric layer (20) may typically include a low-k dielectric material as an inter-metal dielectric (IMD).

[0035] The conductive wiring (30) may include a metal or metal alloy with excellent electrical conductivity. As the semiconductor device becomes smaller, the conductive wiring (30) may have a nanoscale line width, but is not limited thereto. As an example, the dielectric layer (20) may be disposed on the side or bottom of the conductive wiring (30), excluding the top of the conductive wiring (30).

[0036] As described above, selective growth of nanocrystalline graphene may be required to place a capping layer (10) made of nanocrystalline graphene only on the upper surface of the conductive wiring (30), excluding the dielectric layer (20). Below, a method for forming nanocrystalline graphene that is selectively grown only on the upper surface of a pattern on a substrate having a predetermined pattern is described in more detail.

[0037] FIGS. 2a to 2d are drawings illustrating a method for forming nanocrystalline graphene according to an exemplary embodiment. FIG. 3a shows Raman spectra showing whether nanocrystalline graphene was grown in a short time on a predetermined pattern according to an embodiment. FIG. 3b shows Raman spectra showing whether nanocrystalline graphene was grown in a short time on a substrate according to an embodiment.

[0038] Referring to FIG. 2a, power for generating plasma is applied inside a reaction chamber (C) in which a substrate (200) is provided, and a reaction gas for growing nanocrystalline graphene (100 in FIG. 2d) is injected into the reaction chamber.

[0039] Specifically, first, a substrate (200) having a predetermined pattern (300) for growing nanocrystalline graphene (100) inside a reaction chamber is prepared. In this embodiment, nanocrystalline graphene can be selectively grown on the surface of the predetermined pattern (300).

[0040] As an example, the substrate (200) may be provided in a flat plate shape extending along one plane. For example, the substrate (200) may include a second material, for example, a dielectric material having a dielectric constant of about 3.6 or less, for example about 3.3 or less, for example about 3.0 or less. For example, the substrate (200) may be Al2O3, AlN, ZrO2, HfO x(0 < x < 4), may include SiO2, SiCO, SiCN, SiON, SiCOH, AlSiO, or BN (boron nitride). However, it is not limited thereto, and various other dielectric materials may be used on the substrate (200). Additionally, the substrate (200) may include an organic dielectric material.

[0041] A predetermined pattern (300) may be disposed in a trench shape provided on a substrate (200). For example, the predetermined pattern (300) may be provided in the form of a conductive wiring having a nanoscale line width extending along one direction. However, the present disclosure is not limited thereto. As an example, the predetermined pattern (300) may include one or more metals or metal alloys selected from, for example, Cu, Ru, Rh, Ir, Mo, W, Pd, Pt, Co, Ta, Ni, Al, and Ti, which are different from the second material described above.

[0042] Next, referring to FIG. 2b, power for generating plasma is applied from a plasma power source (not shown) into the reaction chamber (C). Here, the power for generating plasma can be approximately 10W to 1500W. However, it is not limited to this.

[0043] For example, an RF (Radio Frequency) plasma generator or a MW (Microwave) plasma generator may be used as the plasma power source. Here, in order to grow nanocrystalline graphene (190), 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.

[0044] 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 state where the electric field is induced, a reaction gas for growing nanocrystalline graphene (100) is injected into the reaction chamber.

[0045] A mixed gas of a carbon source gas, an inert gas, and a hydrogen gas may be used as a reaction gas for the growth of nanocrystalline graphene (100). The carbon source gas may be a gas that supplies carbon for the growth of nanocrystalline graphene. For example, the carbon source gas may include at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon. The carbon-hydrogen gas may include, for example, at least one of methane gas, ethylene gas, and acetylene gas, but is not limited thereto. 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 yIt 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.

[0046] The inert gas may include, for example, at least one of argon gas, nitrogen gas, helium gas, krypton gas, and xenon gas. FIG. 2b illustrates an exemplary case where acetylene gas is used as the carbon source gas and argon gas is used as the inert gas.

[0047] When growing nanocrystalline graphene (100) using plasma, the volume ratio of carbon source gas, inert gas, and hydrogen gas injected into the reaction chamber may be, for example, approximately 1 to 20:5 to 100:1 to 100. At this time, the volume ratio of inert gas and hydrogen gas for selectively growing nanocrystalline graphene (100) only on the upper part of a predetermined pattern (300) may be, for example, approximately 5:100 to 100:1.

[0048] The process temperature for growing nanocrystalline graphene (100) can be approximately 550 degrees or lower, which is lower than the temperature used in a general chemical vapor deposition process. For example, the process temperature inside the reaction chamber can be approximately 300 to 550 degrees.

[0049] And, the process pressure for growing nanocrystalline graphene (100) can be approximately 0.005 Torr to 10 Torr. However, this is only an example and other process pressures may be used.

[0050] In this way, when a reaction gas mixed with carbon source gas, inert gas, and hydrogen gas is introduced into the interior of the reaction chamber (C), the reaction gas is transformed into a plasma state by an electric field applied by plasma power.

[0051] Referring to FIG. 2c, active carbon radicals (C·) are generated by a plasma of reaction gas mixed with carbon source gas, inert gas, and hydrogen gas, and are adsorbed onto the surface of a predetermined pattern (300). 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 predetermined pattern (300) is activated by the adsorption of the generated active carbon radicals (C·) onto the surface of the predetermined pattern (300). Furthermore, the adsorption of active carbon radicals (C·) onto the surface of the predetermined pattern (300) can be accelerated by the plasma of the inert gas continuously inducing the activation of the predetermined pattern (300).

[0052] Referring to FIG. 2d, as described above, as the adsorption of activated carbon radicals (C·) on the surface of a predetermined pattern (300) is accelerated, nanocrystalline graphene (100) can be grown and formed on the surface of the predetermined pattern (300) in a short period of time.

[0053] Accordingly, nanocrystalline graphene (100) can be grown at a relatively fast rate on the surface of a predetermined pattern (300). For example, nanocrystalline graphene (100) can be grown on the surface of the predetermined pattern (300) to a thickness of 0.05 nm or more per minute. However, it is not limited thereto. Accordingly, nanocrystalline graphene (100) can be grown to a desired thickness in a relatively short time. For example, the time for growing nanocrystalline graphene (100) on the surface of the predetermined pattern (300) can be, for example, 60 minutes or less. More specifically, the time for growing nanocrystalline graphene (100) can be 30 minutes or less or 10 minutes or less. However, it is not limited thereto. In this way, nanocrystalline graphene of a desired thickness can be directly formed on the surface of the predetermined pattern (300) in a relatively short time due to the plasma of an inert gas. Such nanocrystalline graphene (100) can have a single layer or a multilayer structure.

[0054] According to the present embodiment, in a plasma chemical vapor deposition process, a mixed gas of carbon source gas, inert gas, and hydrogen gas is used as a reaction gas, and by activating the surface of a predetermined pattern (300) by the plasma of the inert gas among the mixed gas, nanocrystalline graphene (100) can be directly grown and formed on the surface of a predetermined pattern (300) in a relatively short time without a catalyst, even at a relatively low temperature of 550 degrees or less.

[0055] The nanocrystalline graphene (100) described above may contain crystals smaller in size than conventional crystalline graphene. Specifically, the nanocrystalline graphene (100) may contain crystals having a size of approximately 0.5 nm to 70 nm. In this nanocrystalline graphene (100), the proportion of carbon having an sp2 bond structure relative to the total carbon may be, for example, approximately 50% to 99%. The nanocrystalline graphene (100) may contain hydrogen, for example, approximately 1 to 20 at% (atomic percent). Additionally, the nanocrystalline graphene (100) may have a density of, for example, approximately 1.6 to 2.1 g / cc, and a sheet resistance of, for example, approximately 1000 Ohm / sq.

[0056] FIG. 3a shows a Raman spectrum measured on the surface of a predetermined pattern. FIG. 3b shows a Raman spectrum measured on the surface of a substrate. In Examples 1 to 5, copper (Cu) wiring is arranged on the predetermined pattern (300), and a polysilicon substrate is used for the substrate (200). An RF power supply (13.58 MHz) was used as the plasma power source. The power for generating RF plasma was 50 W. As growth conditions, a growth temperature of 400 degrees, a process pressure of 0.02 Torr, and a growth time of 30 minutes were used. Here, the carbon source gas, inert gas, and hydrogen gas included in Example 1 were 5 sccm of acetylene gas, 100 sccm of argon gas, and 0 sccm of hydrogen gas, respectively. In Example 2, the carbon source gas, inert gas, and hydrogen gas used were 5 sccm of acetylene gas, 75 sccm of argon gas, and 25 sccm of hydrogen gas, respectively. In Example 3, the carbon source gas, inert gas, and hydrogen gas used were 5 sccm of acetylene gas, 50 sccm of argon gas, and 50 sccm of hydrogen gas, respectively. In Example 4, the carbon source gas, inert gas, and hydrogen gas used were 5 sccm of acetylene gas, 25 sccm of argon gas, and 75 sccm of hydrogen gas, respectively. In Example 5, the carbon source gas, inert gas, and hydrogen gas used were 5 sccm of acetylene gas, 0 sccm of argon gas, and 100 sccm of hydrogen gas, respectively.

[0057] Referring to FIG. 3a, the spectrum of the upper portion of a predetermined pattern (300) according to Examples 1 to 5 shows that 2D peak, D peak, and G peak appear, indicating that nanocrystalline graphene was grown and formed on the surface of the substrate within a short time of 10 minutes. In this case, the measured thickness of the nanocrystalline graphene was approximately 2 nm.

[0058] Meanwhile, referring to FIG. 3b, in the spectrum of the upper surface of the substrate (200) according to Examples 1 to 5, the 2D peak, D peak, and G peak do not appear in Examples 2 to 5, excluding Example 1 which does not contain hydrogen gas, indicating that nanocrystalline graphene (100) was not grown on the surface of the substrate (200). That is, it can be confirmed that nanocrystalline graphene (100) is selectively formed on the upper surface of the substrate (200) and a predetermined pattern (300) depending on the proportion of hydrogen gas included.

[0059] Figure 4 is a TEM (Transmission Electron Microscope) image showing nanocrystalline graphene grown on a copper pattern by RF (Radio Frequency) plasma according to an exemplary embodiment.

[0060] In Fig. 4, an RF power supply (13.58 MHz) was used as the plasma power source, and the power for generating RF plasma was 50 W. As for the growth conditions, a growth temperature of 700 degrees, a process pressure of 0.02 Torr, and a growth time of 30 minutes were used. In addition, acetylene gas, inert gas, and hydrogen gas included in the reaction gas were 5 sccm of acetylene gas, 50 sccm of argon gas, and 50 sccm of hydrogen gas, respectively.

[0061] Referring to Figure 4, it can be seen that nanocrystalline graphene was grown and formed on the surface of a copper substrate with a thickness of approximately 2 nm in a relatively short time of 30 minutes.

[0062] FIGS. 5a and 5b are drawings illustrating a method for forming nanocrystalline graphene according to a comparative example. FIG. 6 shows Raman spectra showing whether nanocrystalline graphene was grown in a short time on a predetermined pattern and substrate according to an example.

[0063] Referring to FIGS. 5a and 5b, a mixed gas of a carbon source gas and an inert gas may be used as a reaction gas for the growth of nanocrystalline graphene (100). Specifically, FIG. 5a illustrates an exemplary case where acetylene gas is used as the carbon source gas and argon gas is used as the inert gas. In Comparative Examples 1 to 4, copper (Cu) wiring is placed on a predetermined pattern (300), and a SiO2 substrate is used as the substrate (200). As growth conditions, a growth temperature of 400 degrees, a process pressure of 20 mTorr, and a growth time of 30 minutes were used. The carbon source gas and inert gas included in the reaction gas were 5 sccm of acetylene gas and 100 sccm of argon gas, respectively.

[0064] An RF power supply (13.58 MHz) was used as the plasma power source. In Comparative Example 1, the power for generating RF plasma was 50 W. In Comparative Example 2, the power for generating RF plasma was 100 W. In Comparative Example 3, the power for generating RF plasma was 150 W. In Comparative Example 4, the power for generating RF plasma was 200 W.

[0065] FIG. 6 illustrates Raman spectra of nanocrystalline graphene (100) formed on a predetermined pattern (300) and a substrate (200) in a comparative example where the volume ratio of hydrogen gas to inert gas in the reaction gas is 0. Referring to FIG. 6, in the spectrum for the upper part of the predetermined pattern (300) and the substrate (200) according to Comparative Examples 1 to 4, 2D peak, D peak, and G peak appear, indicating that nanocrystalline graphene was grown and formed on the surface of the predetermined pattern (300) and the substrate (200) within a short time of 30 minutes. That is, in Comparative Examples 1 to 4 where the volume ratio of hydrogen gas to inert gas is 0, 2D peak, D peak, and G peak appear in the entire area of ​​the predetermined pattern (300) and the substrate (200), indicating that nanocrystalline graphene (100) was grown on the entire surface of the predetermined pattern (300) and the substrate (200). That is, when the volume ratio of hydrogen gas to inert gas is 0, nanocrystalline graphene (100) can be formed over the entire area of ​​the substrate (200) and a predetermined pattern (300). Therefore, when the volume ratio of hydrogen gas to inert gas is 0, it can be confirmed that nanocrystalline graphene (100) is not selectively formed on the upper surface of the predetermined pattern (300).

[0066] FIGS. 7a and 7b are drawings illustrating a method for forming nanocrystalline graphene according to a comparative example. FIG. 8 is a graph showing the uniformity of nanocrystalline graphene according to an example and a comparative example.

[0067] Referring to FIGS. 7a and 7b, the method for forming nanocrystalline graphene (100) is substantially the same as the method shown in FIGS. 2a to 2d, except that a mixture of carbon source gas and hydrogen gas is used as the reaction gas for the growth of nanocrystalline graphene (100). That is, FIG. 7a shows an exemplary case where acetylene gas is used as the carbon source gas and hydrogen gas is used.

[0068] FIG. 8 illustrates normalized Raman spectra showing the uniformity of nanocrystalline graphene (100) formed on a predetermined pattern (300) in an example in which an inert gas is included in the reaction gas and in a comparative example in which an inert gas is not included. In FIG. 8, the example and comparative examples set the Raman intensity at the point with the highest Raman intensity to 1 and show the uniformity of the nanocrystalline graphene (100) as it spreads from the center (M) of the nanocrystalline graphene (100) outward.

[0069] Referring to FIG. 8, it can be seen that in an example where the reaction gas contains an inert gas, the uniformity of the nanocrystalline graphene (100) is 19.4%, whereas in a comparative example where the reaction gas does not contain an inert gas, the uniformity of the nanocrystalline graphene (100) is 13.5%. Thus, it can be seen that when the reaction gas contains an inert gas, relatively uniform nanocrystalline graphene (100) is grown directly on a predetermined pattern (300).

[0070] FIGS. 9a to 9e are drawings illustrating a method for forming nanocrystalline graphene according to an exemplary embodiment.

[0071] Referring to FIG. 9a, before growing nanocrystalline graphene (100 in FIG. 9e), a pretreatment process is first performed on the surface of a substrate (200) having a predetermined pattern (300) using a reducing gas. Here, the pretreatment process of the substrate (200) having the predetermined pattern (300) may be performed for the purpose of removing impurities or oxygen remaining on the surface of the substrate (200) having the predetermined pattern (300).

[0072] Specifically, first, a substrate (200) having a predetermined pattern (300) for growing nanocrystalline graphene (100) inside a reaction chamber (C) is prepared. Here, the substrate (200) and the predetermined pattern (300) may include various materials described in relation to FIG. 2a.

[0073] Next, referring to FIG. 9b, a gas for pretreatment of a substrate (200) having a predetermined pattern (300) is injected into the interior of a reaction chamber (C). A reducing gas may be used as the gas for 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, in addition to the reducing gas, an inert gas may be additionally injected into the reaction chamber (C). Here, the inert gas may include, for example, at least one of argon gas, neon gas, helium gas, krypton gas, and xenon gas. FIG. 9b illustrates an exemplary case where hydrogen gas is used as the reducing gas and argon gas is used as the inert gas.

[0074] 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. However, the present disclosure is not limited thereto, and the substrate may be pretreated by a heating method using a heating source instead of plasma generation.

[0075] When power for generating plasma is applied from a plasma power source to the reaction chamber (C), 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, plasma for pretreatment of a substrate is formed. The surface of a substrate (200) having a predetermined pattern (300) can be treated by the plasma formed in this manner. Meanwhile, the pretreatment process of the substrate (200) having the predetermined pattern (300) may be carried out while a predetermined voltage is applied to the substrate (200) having the predetermined pattern (300). However, it is not limited to this, and voltage may not be applied to the substrate (200) having the predetermined pattern (300). Accordingly, impurities or oxygen remaining on the surface of the substrate (200) having the predetermined pattern (300) can be removed. When 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.

[0076] The method for forming the nanocrystalline graphene (100) shown in FIGS. 9c to 9e is substantially the same as the process shown in FIGS. 2b to 2d, so for convenience of explanation, the description is omitted here. Through the pretreatment process of the substrate described above, nanocrystalline graphene of a higher quality can be obtained.

[0077] Up to now, exemplary embodiments have been described and illustrated in the accompanying drawings to aid in understanding the present invention. However, it should be understood that these embodiments are merely illustrative of the invention and are not limiting. It should also be understood that the present invention is not limited to the descriptions shown and described. This is because various other variations may occur to those skilled in the art. Explanation of the symbols

[0078] 1: Interconnect structure 10: Capping layer 20: Dielectric layer 30: Conductive wiring 100: Nanocrystalline graphene 200: Substrate 300: Specified pattern

Claims

Claim 1 A method for forming nanocrystalline graphene, comprising: a step of placing a substrate having a predetermined pattern containing a first material in a reaction chamber; a step of injecting a reaction gas mixed with a carbon source gas, an inert gas, and a hydrogen gas into the reaction chamber; a step of generating a plasma of the reaction gas in the reaction chamber; and a step of directly growing nanocrystalline graphene on the surface of the pattern containing the first material using the plasma of the reaction gas at a predetermined process temperature; wherein the first material comprises one or more metals or metal alloys selected from Cu, Ru, Rh, Ir, Mo, W, Pd, Pt, Co, Ta, Ni, Al, and Ti, and the substrate comprises a second material different from the first material, and the second material comprises a dielectric material having a dielectric constant of 3.6 or less. Claim 2 delete Claim 3 delete Claim 4 A method for forming nanocrystalline graphene according to claim 1, wherein the volume ratio of hydrogen gas to inert gas when growing the nanocrystalline graphene using the plasma is 5:100 to 100:

1. Claim 5 A method for forming nanocrystalline graphene according to claim 1, wherein the plasma of the reaction gas comprises RF (Radio Frequency) plasma or MW (Microwave) plasma. Claim 6 A method for forming nanocrystalline graphene according to claim 5, 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 GHz to 2.5 GHz. Claim 7 A method for forming nanocrystalline graphene according to claim 1, wherein the power for generating the plasma of the reaction gas is 10W to 1500W. Claim 8 In claim 1, the nanocrystalline graphene is a method for forming nanocrystalline graphene grown at a process temperature of 550 degrees or lower. Claim 9 In claim 1, the nanocrystalline graphene is formed by a method of growing nanocrystalline graphene at a process pressure of 0.005 Torr to 10 Torr. Claim 10 A method for forming nanocrystalline graphene according to claim 1, wherein the carbon source gas comprises at least one of a hydrocarbon gas and a vapor of a liquid precursor containing carbon. Claim 11 In claim 10, the 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 A method for forming nanocrystalline graphene comprising at least one of an aliphatic hydrocarbon having the chemical formula (1≤x≤12, 2≤y≤26) and its derivatives. Claim 12 A method for forming nanocrystalline graphene according to claim 1, wherein the inert gas comprises at least one of argon gas, nitrogen gas, helium gas, krypton gas and xenon gas. Claim 13 A method for forming nanocrystalline graphene according to claim 1, wherein the nanocrystalline graphene comprises crystals of a size of 0.5 nm to 150 nm. Claim 14 In claim 1, the nanocrystalline graphene is sp relative to the total carbon. 2 A method for forming nanocrystalline graphene having a bonding structure with a carbon content of 50% to 99%. Claim 15 In claim 1, the method for forming nanocrystalline graphene wherein the predetermined pattern is disposed in a trench shape provided on the substrate. Claim 16 A method for forming nanocrystalline graphene according to claim 1, wherein the nanocrystalline graphene comprises 1 to 20 at% (atomic percent) of hydrogen. Claim 17 In claim 1, the nanocrystalline graphene is a method for forming nanocrystalline graphene having a density of 1.6 to 2.1 g / cc. Claim 18 A method for forming nanocrystalline graphene according to claim 1, further comprising the step of pretreating the surface of the substrate using a reducing gas injected into the reaction chamber before growing the nanocrystalline graphene. Claim 19 A method for forming nanocrystalline graphene according to claim 18, wherein the reducing gas comprises at least one of hydrogen, nitrogen, chlorine, fluorine, ammonia, and derivatives thereof. Claim 20 A method for forming nanocrystalline graphene according to claim 19, wherein an inert gas is further injected into the reaction chamber.

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