Film forming method and plasma processing apparatus

Abstract

This film forming method includes a step a) and a step b). In the step a), a substrate is made to be placeable, a stage connected to the ground via a first electrical path is arranged inside of a processing vessel, a conductive ring member connected to the ground via a second electrical path is arranged on the periphery of the stage, and the substrate is placed on the stage inside the processing vessel, in which an electrode is arranged facing the stage. In the step b), while a processing gas including a carbon-containing gas is supplied to the inside of the processing vessel, the impedance of the first electrical path is heightened to greater than the impedance of the second electrical path, power having a frequency not greater than a very high frequency (VHF) band is supplied to the electrode to generate plasma in the processing vessel, and graphene is deposited on the substrate.

Description

Film forming method and plasma processing apparatus

[0001] The present disclosure relates to a film forming method and a plasma processing apparatus.

[0002] Patent Document 1 listed below discloses "a pretreatment method to be performed before growing graphene by a CVD method on a catalytic metal layer formed on a target body, the pretreatment method comprising a plasma treatment step of activating the catalytic metal layer by applying plasma of a treatment gas containing a reducing gas and a nitrogen-containing gas to the catalytic metal layer."

[0003] JP 2013-100205 A

[0004] The present disclosure provides a technique that enables graphene to be deposited on a substrate even with plasma generated by power having a frequency equal to or lower than the VHF (Very High Frequency) band.

[0005] A film formation method according to one aspect of the present disclosure includes steps a) and b). In step a), a substrate is placed on a stage inside a processing vessel, the stage being configured to support a substrate and connected to ground via a first electrical path, a conductive ring member being arranged around the stage and connected to ground via a second electrical path, and an electrode being arranged opposite the stage. In step b), a processing gas including a carbon-containing gas is supplied into the processing vessel, and while the impedance of the first electrical path is made higher than the impedance of the second electrical path, power having a frequency equal to or lower than a VHF (Very High Frequency) band is supplied to the electrode to generate plasma in the processing vessel, and graphene is formed on the substrate.

[0006] According to the present disclosure, graphene can be deposited on a substrate even with plasma generated by power with a frequency below the VHF band.

[0007] FIG. 1 is a diagram schematically illustrating a plasma processing apparatus 1 according to an embodiment. FIG. 2 is a diagram schematically illustrating an example of a flow of high-frequency power according to an embodiment. FIG. 3A is a diagram illustrating an ion energy distribution in a first experiment. FIG. 3B is a diagram illustrating an ion energy distribution in the first experiment. FIG. 4 is a flowchart illustrating an example of a film forming method according to an embodiment. FIG. 5 is a diagram illustrating a Raman spectrum of a substrate on which a graphene film is formed in a second experiment.

[0008] Hereinafter, embodiments of a film forming method and a plasma processing apparatus will be described in detail with reference to the drawings. Note that the following embodiments do not limit the disclosed film forming method and plasma processing apparatus.

[0009] Conventionally, a technique has been known in which, for example, microwaves are introduced into a chamber to generate plasma and graphene is deposited on a substrate. For example, microwaves of 860 MHz are used to generate the plasma.

[0010] To improve the productivity of graphene film formation, a multi-wafer type film formation device is required. However, film formation devices that generate plasma using microwaves are difficult to use for multi-wafer formation. For multi-wafer formation, a plasma processing device that generates plasma using power in the VHF band or at a frequency lower than the VHF band is preferred. The VHF band is a frequency range of 30 to 300 MHz.

[0011] However, plasma generated by power with a frequency below the VHF band (30 MHz or less) has high ion energy, making it difficult to deposit continuous graphene films by ion bombardment. Therefore, there is a need for a technology that enables graphene to be deposited on a substrate even with plasma generated by power with a frequency below the VHF band.

[0012] (Embodiment) (Configuration of Plasma Processing Apparatus) Next, an embodiment will be described. FIG. 1 is a diagram schematically illustrating a plasma processing apparatus 1 according to an embodiment. The plasma processing apparatus 1 illustrated in FIG. 1 includes a chamber 10. The chamber 10 provides an internal space therein. The chamber 10 may include a chamber body 12. The chamber body 12 has a substantially cylindrical shape. Walls of the chamber 10, including a side wall 12a and a bottom wall 12b, are provided by the chamber body 12. The internal space of the chamber 10 is provided within the chamber body 12. The chamber body 12 is formed of a conductive metal such as aluminum. The chamber body 12 is grounded via wiring 13. In the embodiment, the chamber 10 corresponds to a processing vessel according to the present disclosure.

[0013] The plasma processing apparatus 1 further includes a substrate support 14. The substrate support 14 is provided in the chamber 10. The substrate support 14 is configured to support a substrate W placed thereon. The substrate support 14 has a main body. The main body of the substrate support 14 is made of, for example, aluminum nitride, and may have a disk shape. In the embodiment, the substrate support 14 corresponds to a stage of the present disclosure.

[0014] The substrate support 14 is supported by a support member 16. The support member 16 is formed in a cylindrical shape. An opening 12c is formed near the center of the bottom wall 12b of the chamber 10. The substrate support 14 passes through the opening 12c and is connected to a flange 25 below the bottom wall 12b. The flange 25 is formed flat and wider than the opening 12c. The flange 25 can be raised and lowered by an elevating mechanism 26. As the flange 25 rises and lowers, the support member 16 and the substrate support 14 rise and lower together with the flange 25. As the substrate support 14 rises and lowers, the distance between the substrate W placed on the substrate support 14 and the upper electrode 30, which will be described later, is changed. The elevating mechanism 26 is controlled by a control unit 80, which will be described later.

[0015] The bottom wall 12b of the chamber 10 and the flange 25 are connected via a bellows 27. This maintains airtightness within the chamber 10 even when the flange 25 is raised and lowered by the lifting mechanism 26. The substrate support 14 is electrically isolated from the chamber 10. In one embodiment, the substrate support 14 is electrically isolated from the chamber 10 by connecting at least one of the substrate support 14 and the support member 16, and the support member 16 and the flange 25 via an insulating member.

[0016] The substrate support 14 can be raised and lowered within the chamber 10 by an elevating mechanism 26 via a flange 25 and a support member 16. Fig. 1 shows the substrate support 14 in a raised state.

[0017] When loading and unloading the substrate W, the substrate support part 14 is lowered by the lifting mechanism 26 to a transfer position where the substrate W can be loaded and unloaded. A load / unload port (not shown) is formed in the side wall 12a of the chamber 10 at a position approximately the same height as the transfer position. The load / unload port can be opened and closed by a gate valve. The substrate W is loaded into the chamber 10 through the load / unload port (not shown) by a transfer mechanism such as a transfer arm, and placed on the substrate support part 14 lowered to the transfer position.

[0018] When processing the substrate W, the substrate support part 14 is raised by the lifting mechanism 26. When performing a film formation process on the substrate W, the height of the substrate support part 14 is adjusted to a processing position where a predetermined distance is set between the upper surface of the substrate support part 14 and the lower surface of an upper electrode 30 (described later). The predetermined distance is determined by the film formation conditions.

[0019] The substrate support 14 includes a lower electrode 18. The lower electrode 18 is formed of a conductive metal such as aluminum and is embedded in the body of the substrate support 14. The substrate support 14 may also include a heater 20. The heater 20 is embedded in the body of the substrate support 14. The heater 20 is a resistive heating element and is formed of a high-melting-point metal such as molybdenum. The heater 20 is connected to a heater power supply 22 via wiring 28b provided inside the substrate support 14, the support member 16, and the flange 25. The heater power supply 22 is provided outside the chamber 10. The heater 20 receives power from the heater power supply 22 and generates heat to heat the substrate W. The substrate support 14 may be entirely formed of a conductive metal such as aluminum, and the entire substrate support 14 may function as the lower electrode 18. In this case, a cover is provided on the substrate support 14 to cover the top and side surfaces. The cover is made of an insulating material.

[0020] The plasma processing apparatus 1 further includes a ring electrode 70. The ring electrode 70 is made of a conductive metal such as aluminum and has a flat ring shape. The ring electrode 70 is provided outside the space between the lower electrode 18 and the upper electrode 30 and within the chamber 10. The ring electrode 70 is provided so as to surround the periphery of the substrate support 14 in a raised position. The ring electrode 70 is provided along the sidewall of the chamber 10 (or the chamber body 12). The inner diameter of the ring electrode 70 is formed slightly larger than the outer diameter of the substrate support 14, and the ring electrode 70 is positioned with a gap between it and the side surface of the substrate support 14 so as not to come into contact with the substrate support 14 as it rises and falls. The position of the ring electrode 70 is adjusted so that the upper surface of the substrate support 14, which is set to the processing position, and the upper surface of the ring electrode 70 are, for example, at the same height. The position of the ring electrode 70 is also adjusted so that the upper surface of the ring electrode 70 is higher than the upper surface of the substrate support 14, which is set to the processing position. Furthermore, for example, the position of the ring electrode 70 is adjusted so that the upper surface of the ring electrode 70 is lower than the upper surface of the substrate support 14, which is set at the processing position. The ring electrode 70 is connected to the sidewall 12a of the chamber body 12 and is electrically connected to the chamber body 12. The chamber body 12 is grounded via wiring 13. An electrical path 52 is formed between the ring electrode 70 and the chamber body 12 and is connected to ground via the chamber body 12 and wiring 13. The electrical path 52 is formed by the chamber body 12 and wiring 13, which are electrically connected to the ring electrode 70. The ring electrode 70 may be a mesh-like electrode providing a plurality of holes. Alternatively, the ring electrode 70 may be a slit-like electrode providing a plurality of elongated holes. In the embodiment, the ring electrode 70 corresponds to the ring member of the present disclosure, and the electrical path 52 corresponds to the second electrical path of the present disclosure.

[0021] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 14. The upper electrode 30 constitutes the ceiling of the chamber 10. The upper electrode 30 is electrically isolated from the chamber body 12. In one embodiment, the upper electrode 30 is fixed to the top of the chamber body 12 via an insulating member 32. In the embodiment, the upper electrode 30 corresponds to the electrode of the present disclosure.

[0022] In one embodiment, the upper electrode 30 is configured as a shower head. The upper electrode 30 may include a base member 33 and a top plate 34. The upper electrode 30 may further include an intermediate member 35. The base member 33, the top plate 34, and the intermediate member 35 are conductive and made of, for example, aluminum. The base member 33 is provided above the top plate 34. A heat insulating member 37 may be provided on the base member 33. The intermediate member 35 has a substantially ring shape and is sandwiched between the base member 33 and the top plate 34. The base member 33 and the top plate 34 provide a gas diffusion space 30d therebetween. The base member 33 provides a gas inlet port 33a connected to the gas diffusion space 30d. The top plate 34 provides a plurality of gas holes 34a. The plurality of gas holes 34a extend downward from the gas diffusion space 30d and penetrate the top plate 34 along its thickness direction.

[0023] The plasma processing apparatus 1 further includes a gas supply unit 36. The gas supply unit 36 ​​is configured to supply gas into the chamber 10. In one embodiment, the gas supply unit 36 ​​is connected to the gas inlet port 33a via a pipe 38. The gas supply unit 36 ​​may include one or more gas sources, one or more flow rate controllers, and one or more on-off valves. Each of the one or more gas sources is connected to the gas inlet port 33a via a corresponding flow rate controller and a corresponding on-off valve. The gas supply unit 36 ​​supplies various gases, such as process gases used in a degassing process, an annealing process, and a film formation process, which will be described later.

[0024] The plasma processing apparatus 1 further includes an exhaust device 40. The exhaust device 40 includes a pressure controller such as an automatic pressure control valve and a vacuum pump such as a turbomolecular pump or a dry pump. The exhaust device 40 is connected to an exhaust pipe 42. The exhaust pipe 42 is connected to the bottom wall 12b of the chamber 10 and communicates with the internal space of the chamber 10. The exhaust pipe 42 may also be connected to a side wall of the chamber 10.

[0025] The plasma processing apparatus 1 further includes a high-frequency power supply 44. The high-frequency power supply 44 is connected to the upper electrode 30 via a matching box 46. The high-frequency power supply 44 supplies power of a frequency below the VHF band (300 MHz or less) to the upper electrode 30. For example, the high-frequency power supply 44 supplies power of a frequency between 100 kHz and 13.56 MHz to the upper electrode 30. In the embodiment, the high-frequency power supply 44 corresponds to the power supply of the present disclosure.

[0026] The high frequency power supply 44 is connected to the upper electrode 30 via a matching box 46. The matching box 46 has a matching circuit that matches the impedance of the load of the high frequency power supply 44 to the output impedance of the high frequency power supply 44.

[0027] The plasma processing apparatus 1 further includes an impedance circuit 50. The lower electrode 18 of the substrate support member 14 is grounded via the wiring 28a. The impedance circuit 50 is provided between the wiring 28a and the lower electrode 18 and ground. An electrical path 51 is formed between the lower electrode 18 of the substrate support member 14 and the wiring 28a via the impedance circuit 50, and the wiring 28a connects the lower electrode 18 of the substrate support member 14 to ground. The electrical path 51 is composed of the wiring 28a electrically connected to the lower electrode 18 and the impedance circuit 50. In the embodiment, the electrical path 51 corresponds to the first electrical path of the present disclosure.

[0028] The impedance circuit 50 can provide a variable impedance between the lower electrode 18 and ground. The impedance circuit 50 can include a series or parallel circuit of an inductor and a capacitor. The inductor can be a variable inductor, and the capacitor can be a variable capacitor.

[0029] The impedance of the impedance circuit 50 is set so that the impedance of the electrical path 51 is higher than the impedance of the electrical path 52. The impedance of the impedance circuit 50 can be set by a control unit 80, which will be described later. Note that the impedance of the impedance circuit 50 is set appropriately in advance, but may also be dynamically changed by the control unit 80 during the process of forming a film on the substrate W.

[0030] The plasma processing apparatus 1 further includes a control unit 80. The control unit 80 is configured to control each unit of the plasma processing apparatus 1. The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, etc. The storage unit of the control unit 80 stores a control program and recipe data. The processor of the control unit 80 executes the control program and controls each unit of the plasma processing apparatus 1 in accordance with the recipe data. The control unit 80 controls each unit of the plasma processing apparatus 1, thereby executing the film formation method according to the embodiment in the plasma processing apparatus 1.

[0031] Next, a flow of film formation on a loaded substrate W under the control of the control unit 80 by the plasma processing apparatus 1 according to the embodiment will be briefly described.

[0032] When a substrate W is loaded into the plasma processing apparatus 1, the control unit 80 controls the lifting mechanism 26 to lower the substrate support member 14 to a transfer position. The substrate W is placed on the substrate support member 14 by a transfer mechanism such as a transfer arm (not shown). When a film is to be formed on the substrate W, the control unit 80 controls the lifting mechanism 26 to raise the substrate support member 14. The control unit 80 controls the exhaust device 40 to reduce the pressure inside the chamber 10. The control unit 80 controls the gas supply unit 36 ​​to supply various gases used for film formation from the gas supply unit 36 ​​and introduce a process gas into the chamber 10 from the upper electrode 30. The control unit 80 then controls the high-frequency power supply 44 to supply power of a frequency below the VHF band from the high-frequency power supply 44 to the upper electrode 30 to generate plasma in the chamber 10, and film formation is then performed on the substrate W.

[0033] The impedance of the impedance circuit 50 is set so that the impedance of the electrical path 51 is higher than the impedance of the electrical path 52. For example, the impedance of the impedance circuit 50 is set so that the impedance of the electrical path 51 is 10 times or more higher than the impedance of the electrical path 52. For example, in the electrical path 52, although the ring electrode 70 is a conductor and therefore has low electrical resistance, the sheath of the plasma generated around the ring electrode 70 has an impedance of about several hundred ohms. For this reason, the impedance of the impedance circuit 50 is set so that the impedance of the electrical path 51 is several kΩ or more.

[0034] Fig. 2 is a diagram schematically illustrating an example of the flow of power according to the embodiment. Fig. 2 shows a schematic configuration inside the chamber 10. Note that Fig. 2 illustrates a case where the substrate support 14 is formed from a conductive metal, and the entire substrate support 14 serves as the lower electrode 18. A cover ring 15 is provided on the substrate support 14. The cover ring 15 covers the peripheral edge and side surfaces of the substrate support 14. The cover ring 15 is formed of, for example, alumina.

[0035] The power supplied from the upper electrode 30 flows from the substrate support 14 (lower electrode 18) to ground via the electrical path 51, and also flows from the ring electrode 70 to ground via the electrical path 52. The impedance of the electrical path 51 is set to be higher than the impedance of the electrical path 52. For example, the impedance of the electrical path 51 is set to be 10 times or more higher than the impedance of the electrical path 52. This weakens the electrical coupling between the upper electrode 30 and the lower electrode 18, and most of the power supplied from the upper electrode 30 flows from the ring electrode 70 to ground via the electrical path 52. This reduces the current flowing through the lower electrode 18, and reduces the ion energy imparted to the substrate W on the substrate support 14.

[0036] Next, a description will be given of a first experiment for measuring the ion energy distribution of the plasma processing apparatus 1. The first experiment described below does not limit the present disclosure.

[0037] (First Experiment) In the first experiment, the ion energy distribution in plasma was measured in the plasma processing apparatus 1 without the ring electrode 70 and in the plasma processing apparatus 1 with the ring electrode 70. In the first experiment, the power supplied from the high-frequency power supply 44 was varied to 100, 200, 300, 500, and 800 W, and the ion energy distribution in plasma was measured. In the plasma processing apparatus 1 with the ring electrode 70, the impedance of the electrical path 51 was measured as 10 times higher than the impedance of the electrical path 52. Other conditions in the first experiment are shown below.

[0038] <Conditions of the first experiment> Gases supplied into the chamber 10: Ar gas and H ２ Mixture of gases Frequency of power supplied from high frequency power supply 44: 450 kHz Pressure in chamber 10: 500 mTorr (66.7 Pa) Temperature of substrate W: less than 60° C. Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 13.5 mm

[0039] An example of the results of determining the ion energy distribution will be described. FIGS. 3A and 3B are diagrams showing the ion energy distributions of the first experiment. FIG. 3A shows the ion energy distribution measured using the plasma processing apparatus 1 without the ring electrode 70. FIG. 3B shows the ion energy distribution measured using the plasma processing apparatus 1 with the ring electrode 70. As shown in FIG. 3A , in the plasma processing apparatus 1 without the ring electrode 70, ions with an ion energy of 40 eV or more are generated in the plasma. On the other hand, as shown in FIG. 3B , in the plasma processing apparatus 1 with the ring electrode 70, the ion energy of the ions contained in the plasma can be reduced to less than 10 eV. In graphene film formation, it is necessary to keep the ion energy of the plasma low. Therefore, the plasma processing apparatus 1 with the ring electrode 70, as in the embodiment, can be used to form graphene films.

[0040] Next, a description will be given of a film formation method for forming graphene on a substrate W using the plasma processing apparatus 1 according to the embodiment. Fig. 4 is a flowchart showing an example of the film formation method according to the embodiment.

[0041] A degassing process is performed to remove residual oxygen from the chamber 10 (step S10). The degassing process is performed before the substrate W is placed on the substrate support 14. In the degassing process, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is preferably the same as or longer than the distance in the annealing process described below. More preferably, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is 80 mm to 130 mm. The pressure in the chamber 10 during the degassing process is preferably within the range of 100 mTorr to 500 mTorr (13.3 to 66.66 Pa). In the degassing process, a process gas containing an inert gas is supplied into the chamber 10 to generate plasma, and the interior of the chamber 10 is exposed to the plasma to remove residual oxygen from the chamber 10. Examples of inert gases contained in the process gas used in the degassing process include N2 gas and Ar gas. The process gas used in the degassing process includes at least one of N2 gas and Ar gas. For example, the control unit 80 controls the lifting mechanism 26 to raise the substrate support 14 to a position where the upper surface of the substrate support 14 is 80 mm to 130 mm above the lower surface of the substrate support 14. The control unit 80 controls the exhaust device 40 to reduce the pressure in the chamber 10 to 100 mTorr to 500 mTorr (13.3 to 66.66 Pa). The control unit 80 controls the gas supply unit 36 ​​to supply a process gas containing an inert gas from the gas supply unit 36 ​​and introduce the process gas into the chamber 10 through the upper electrode 30. The control unit 80 then controls the high-frequency power supply 44 to supply power of a frequency below the VHF band from the high-frequency power supply 44 to the upper electrode 30 to generate plasma in the chamber 10 and remove residual oxygen from the chamber 10. The frequency of the power supplied from the high-frequency power supply 44 may be the same as that of the film formation process described below. In an embodiment, step S10 corresponds to step d) of the present disclosure. Note that the degassing process may be omitted.

[0042] Next, the substrate W on which a film is to be formed is loaded (step S11). For example, the control unit 80 controls the lifting mechanism 26 to lower the substrate support 14 to the transfer position. The substrate W is placed on the substrate support 14 by a transfer mechanism such as a transfer arm (not shown). The substrate W preferably has a metal-containing film on its surface from which graphene can be formed. The metal-containing film is a film made of any of Ru, Co, Cu, W, Mo, any oxide, any nitride, or any oxynitride, or silicon, a silicon-containing oxide, a silicon-containing nitride, or a silicon-containing oxynitride. The metal-containing film may be formed on the substrate W in the plasma processing apparatus 1 before graphene is formed. In the embodiment, step S11 corresponds to step a) of the present disclosure.

[0043] Next, the substrate W is annealed (step S12). The annealing process is performed as a pre-process for the film formation process described below to remove metal oxides from the metal-containing film on the surface of the substrate W. In the annealing process, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is preferably the same as or shorter than that in the degassing process described above. In the annealing process, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is preferably 80 mm to 130 mm. The pressure inside the chamber 10 during the annealing process is preferably within the range of 50 mTorr to 2000 mTorr (6.7 to 266.4 Pa). In the annealing process, the surface of the metal-containing film on the substrate W is exposed to a process gas containing a reducing gas to remove metal oxides from the metal-containing film. Examples of reducing gases contained in the process gas for the annealing process include hydrogen gas, CO gas, and hydrocarbon gas. The process gas for the annealing process contains at least one of hydrogen gas, CO gas, and hydrocarbon gas. The process gas for the annealing treatment may further contain an inert gas. Examples of inert gases that may be contained in the process gas for the annealing treatment include Ar gas, He gas, N gas, and Kr gas. The process gas for the annealing treatment may include at least one of Ar gas, He gas, N gas, and Kr gas. For example, the control unit 80 controls the lifting mechanism 26 to raise the substrate support unit 14 to a position where the upper surface of the substrate support unit 14 is the same distance from the lower surface of the substrate support unit 14 as during the degassing treatment or is closer to the upper surface of the substrate support unit 14 than during the degassing treatment. The control unit 80 controls the exhaust device 40 to reduce the pressure in the chamber 10 to 50 mTorr to 2000 mTorr (6.7 to 266.4 Pa). The control unit 80 controls the gas supply unit 36 ​​to supply a process gas containing a reducing gas from the gas supply unit 36 ​​and introduce the process gas into the chamber 10 from the upper electrode 30. The annealing treatment may include a first annealing treatment in which the surface of the metal-containing film on the substrate W is exposed to a reducing gas and an inert gas, and a second annealing treatment in which the surface of the metal-containing film on the substrate W is exposed to an inert gas after the first annealing treatment. In the embodiment, step S12 corresponds to step c) of the present disclosure. The annealing treatment may be omitted.

[0044] Next, a film formation process is performed to form a graphene film on the substrate W (step S13). In the film formation process, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is preferably the same as or shorter than that in the annealing process described above. In the film formation process, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is preferably 10 mm to 80 mm, and more preferably 20 mm to 30 mm. In the film formation process, a process gas containing a carbon-containing gas is supplied into the chamber 10 to generate plasma, and a graphene film is formed on the metal-containing film on the substrate W. Examples of the carbon-containing gas include hydrocarbon-based gases. Examples of the hydrocarbon-based gas include C ２ H ２ Gas, CH ４ Gas, C ２ H ４ The process gas for the film formation process is a CxHy gas (x and y are integers of 1 or more). ２ H ２ Gas, CH ４ Gas, C ２ H ４The process gas may include at least one of CxHy gases (x and y are integers equal to or greater than 1), such as a gas. The process gas may also include an inert gas. Examples of inert gases include Ar gas, He gas, N2 gas, and Kr gas. The process gas for the film formation process may include at least one of Ar gas, He gas, N2 gas, and Kr gas. The temperature of the substrate W during the film formation process is preferably within the range of 300°C to 500°C. The pressure within the chamber 10 during the film formation process is preferably within the range of 200 mTorr to 600 mTorr (26.7 to 80 Pa). The power of the electric power used during the film formation process is preferably within the range of 50 W to 1000 W. The frequency of the electric power used during the film formation process may be any frequency below the VHF band, and is preferably within the range of 100 kHz to 13.56 MHz. For example, the control unit 80 controls the lifting mechanism 26 to raise the substrate support 14 to a predetermined processing position where the upper surface of the substrate support 14 is 10 mm to 80 mm above the lower surface of the substrate support 14. The position of the ring electrode 70 is adjusted so that the upper surface of the substrate support 14 raised to the processing position is at the same height as the upper surface of the ring electrode 70. The ring electrode 70 surrounds the periphery of the substrate support 14 at the processing position. The control unit 80 controls the heater power supply 22 to heat the substrate W using the heater 20 so that the temperature of the substrate W is within a range of 300°C to 500°C. The control unit 80 may adjust the temperature of the substrate W to the film formation temperature from the time of the annealing process. The control unit 80 controls the exhaust device 40 to reduce the pressure inside the chamber 10 to 200 mTorr to 600 mTorr (26.7 to 80 Pa). The control unit 80 controls the gas supply unit 36 ​​to supply a process gas containing a carbon-containing gas from the gas supply unit 36 ​​and introduce the process gas into the chamber 10 through the upper electrode 30. Then, the control unit 80 controls the high-frequency power supply 44 to supply power having a frequency equal to or lower than the VHF band from the high-frequency power supply 44 to the upper electrode 30 to generate plasma in the chamber 10 and deposit a graphene film on the metal-containing film of the substrate W. In the embodiment, step S13 corresponds to step b) of the present disclosure.

[0045] Next, the substrate W on which the graphene film has been formed is unloaded (step S14). For example, the control unit 80 controls the lifting mechanism 26 to lower the substrate support unit 14 to the transfer position. The substrate W is taken out of the substrate support unit 14 by a transfer mechanism such as a transfer arm (not shown) and unloaded.

[0046] Next, a second experiment and a third experiment will be described in which graphene was formed on a substrate W using the plasma processing apparatus 1 according to the embodiment. The second experiment and the third experiment described below do not limit the present disclosure.

[0047] (Second Experiment) In the second experiment, graphene was formed on a substrate W by the film formation method shown in Fig. 4. In the second experiment, graphene was formed on a substrate W having a Co film formed on its surface as a metal-containing film. The common processing conditions for the degassing process (step S10), the annealing process (step S12), and the film formation process (step S13) are shown below. <Common Processing Conditions for the Second Experiment> Frequency of power supplied from the high-frequency power supply 44: 450 kHz Temperature of the substrate W: 400°C

[0048] The individual conditions for the degassing process, annealing process, and film formation process are shown below. The gas flow rates for the degassing process, annealing process, and film formation process were set to appropriate values. <Processing conditions for the degassing process in the second experiment> Gas supplied into the chamber 10: N ２ Gas Power of electric power supplied from the high frequency power supply 44: 300 W Pressure in the chamber 10: 300 mTorr (40.0 Pa) Distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30: 80 mm Processing time: 10 min <Processing conditions for the annealing process in the second experiment> Gas supplied into the chamber 10: H ２ Gas Power of electric power supplied from the high frequency power supply 44: 0 W (plasma-less) Pressure in the chamber 10: 50 mTorr (6.7 Pa) Distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30: 80 mm Processing time: 10 min <Processing conditions for the film formation process in the second experiment> Gas supplied into the chamber 10: C ２ H ２ Gas and H ２Mixture of gas and Ar gas Power of power supplied from high frequency power supply 44: 300 W Pressure in chamber 10: 500 mTorr (66.7 Pa) Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 20 mm Processing time: 1 min

[0049] In the second experiment, CoOx was removed from the Co film on the surface of the substrate W by annealing, and graphene was formed on the Co film of the substrate W by film formation. In the second experiment, the Raman spectrum of the substrate W on which the graphene film was formed was measured. FIG. 5 shows the Raman spectrum of the substrate W on which the graphene film was formed in the second experiment. The horizontal axis of FIG. 5 represents the wavelength shift amount (Raman shift (cm)) from the excitation wavelength. -1 )). The vertical axis shows the signal intensity of each wavelength normalized to a predetermined signal intensity of 1. A G peak and a D peak can be confirmed in the Raman spectrum shown in FIG. 5. This confirms that a graphene film has been formed on the substrate W.

[0050] (Third Experiment) In the third experiment, graphene was formed on a substrate W by the film formation method shown in FIG. 4 . In the third experiment, graphene was formed on a substrate W having a Ru film formed on its surface as a metal-containing film. In the third experiment, a second annealing process was performed after a first annealing process in the annealing process (step S12). The common process conditions for the degassing process (step S10), the first annealing process (step S12), the second annealing process (step S12), and the film formation process (step S13) are shown below. <Common Process Conditions for the Third Experiment> Frequency of power supplied from the high-frequency power supply 44: 450 kHz Temperature of the substrate W: 400° C.

[0051] The individual conditions for the degassing process, annealing process, and film formation process are shown below. The gas flow rates for the degassing process, annealing process, and film formation process were set to appropriate values. <Processing conditions for the degassing process in the third experiment> Gas supplied into the chamber 10: N ２Gas Power of electric power supplied from the high frequency power supply 44: 300 W Pressure in the chamber 10: 300 mTorr (40.0 Pa) Distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30: 130 mm Processing time: 10 min <Processing conditions for the first annealing treatment in the third experiment> Gas supplied into the chamber 10: H ２ Mixture of Ar gas and Ar gas Power supplied from high frequency power supply 44: 0 W (plasma-less) Pressure inside chamber 10: 400 mTorr (53.2 Pa) Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 90 mm Processing time: 1 min <Processing conditions for second annealing treatment in third experiment> Gas supplied into chamber 10: Ar gas Power supplied from high frequency power supply 44: 0 W (plasma-less) Pressure inside chamber 10: 2000 mTorr (266.6 Pa) Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 90 mm Processing time: 10 min <Processing conditions for film formation treatment in third experiment> Gas supplied into chamber 10: Ar gas Power supplied from high frequency power supply 44: 0 W (plasma-less) Pressure inside chamber 10: 2000 mTorr (266.6 Pa) Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 90 mm Processing time: 10 min ２ H ２ Gas and H ２ Mixture of gas and Ar gas Power of power supplied from high frequency power supply 44: 300 W Pressure in chamber 10: 300 mTorr (40.0 Pa) Distance between the top surface of substrate support 14 and the bottom surface of upper electrode 30: 60 mm Processing time: 1 min

[0052] In the third experiment, RuOx is removed from the Ru film on the surface of the substrate W by the first annealing treatment and the second annealing treatment, and graphene is formed on the Ru film of the substrate W by the film formation treatment. As a result of measuring the Raman spectrum of the substrate W on which the graphene film was formed in the third experiment, a G peak and a D peak can be confirmed in the Raman spectrum. This confirms that a graphene film has been formed on the substrate W.

[0053] In addition, graphene was formed on the substrate W by changing the frequency of the power supplied from the high-frequency power supply 44, and as a result, a graphene film could be formed on the substrate W at frequencies between 100 kHz and 13.56 MHz. Furthermore, graphene was formed on the substrate W by changing the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30, and as a result, a graphene film could be formed on the substrate W at distances between 10 mm and 80 mm. However, when the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is shortened, carbon nanowalls (CNWs) are formed in the graphene film. To form a graphene film with good continuity, it is more preferable that the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 be between 30 mm and 60 mm.

[0054] Here, in conventional graphene deposition using microwaves, graphene cannot be deposited unless the pressure inside the chamber is reduced to a low pressure of about 20 mTorr to 80 mTorr (2.7 to 10.7 Pa).

[0055] In contrast, the plasma processing apparatus 1 according to the embodiment can form graphene even at a high pressure of 500 mTorr (66.7 Pa), for example, as shown in the processing conditions for the film formation process in the second experiment described above. This eliminates the need for a turbomolecular pump in the exhaust device 40 of the plasma processing apparatus 1. Furthermore, when considering improving the productivity of graphene film formation, the configuration of the present disclosure can be used in a multi-wafer type film formation apparatus. Furthermore, because graphene can be formed with a short gap, the chamber volume can be reduced, and the amount of film formation gas used can be reduced.

[0056] In the above embodiment, the electrical path 52 from the ring electrode 70 to ground is a conductive path that runs from the ring electrode 70 to ground via the chamber body 12 and wiring 13. However, the disclosed technology is not limited to this. For example, the electrical path 52 may be any conductive path that allows current to flow from the ring electrode 70 to ground. For example, the ring electrode 70 may be insulated from the chamber body 12, and a grounded wiring may be connected to the ring electrode 70, and the wiring may serve as the electrical path 52. The electrical path 51 may also be any conductive path that runs from the lower electrode 18 of the substrate support 14 to ground.

[0057] The embodiment has been described above. As described above, the film formation method according to the embodiment includes step a) (step S11) and step b) (step S13). In step a), a substrate W is placed on a substrate support 14 inside a chamber 10, the chamber 10 having a substrate support 14 connected to ground via an electrical path 51 disposed therein, a conductive ring electrode 70 connected to ground via an electrical path 52 disposed around the substrate support 14, and an upper electrode 30 disposed opposite the substrate support 14. In step b), a process gas containing a carbon-containing gas is supplied into the chamber 10, and power having a frequency equal to or lower than the VHF band is supplied to the upper electrode 30 to generate plasma in the chamber 10, thereby forming a graphene film on the substrate W. As a result, the film formation method according to the embodiment can form a graphene film on the substrate W even with plasma generated by power having a frequency equal to or lower than the VHF band.

[0058] Furthermore, in step b), the impedance of the electrical path 51 is at least 10 times higher than the impedance of the electrical path 52. As a result, most of the power supplied from the upper electrode 30 flows from the ring electrode 70 to the ground via the electrical path 52. This significantly reduces the ion energy of ions contained in the plasma. As a result, the film deposition method according to the embodiment can deposit graphene on the substrate W even with plasma generated by power with a frequency equal to or lower than the VHF band.

[0059] In step b), the distance between the upper surface of the substrate support member 14 and the lower surface of the upper electrode 30 is 10 mm to 80 mm. In step b), power having a frequency between 100 kHz and 13.56 MHz is supplied to the upper electrode 30. The carbon-containing gas is a hydrocarbon gas. The process gas includes an inert gas. The inert gas is at least one of Ar gas, He gas, N2 gas, and Kr gas. The substrate support member 14 is provided with a heater. In step b), the heater adjusts the temperature of the substrate W to within a range of 300°C to 500°C. In step b), the pressure in the chamber 10 is 200 mTorr to 600 mTorr. In step b), the power supplied to the upper electrode 30 is within a range of 50 W to 1000 W. The substrate W has a metal-containing film formed on its surface, on which graphene can be formed. The metal-containing film is any one of a film of Ru, Co, Cu, W, and Mo, a film of any oxide, and a film of any nitride. As a result, the film deposition method according to the embodiment can deposit graphene on the substrate W even with plasma generated by power with a frequency equal to or lower than the VHF band.

[0060] The film forming method according to the embodiment further includes a step c) (step S12). In the step c), the surface of the metal-containing film is exposed to a second process gas containing a reducing gas before the step b). In the step c), the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is 80 mm to 130 mm. In the step c), the pressure in the chamber 10 is 50 mTorr to 2000 mTorr. The reducing gas is at least one of hydrogen gas, CO gas, and hydrocarbon gas. In this way, the film forming method according to the embodiment can remove metal oxide from the metal-containing film on the surface of the substrate W.

[0061] Furthermore, the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is configured to be changeable. In step c), the distance between the upper surface of the substrate support 14 and the lower surface of the upper electrode 30 is set to be the same as or longer than that in step b). This allows the film formation method according to the embodiment to remove metal oxide from the metal-containing film on the surface of the substrate W.

[0062] The film formation method according to the embodiment further includes a step d) (step S10). In the step d), before the steps a) and b), a third process gas containing an inert gas is supplied into the chamber 10 while power is supplied to the upper electrode 30 to remove residual oxygen from the chamber 10. In the step d), the distance between the top surface of the substrate support 14 and the bottom surface of the upper electrode 30 is 80 mm to 130 mm. This allows the film formation method according to the embodiment to remove residual oxygen from the chamber 10 during the graphene film formation.

[0063] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0064] Furthermore, the following supplementary notes are disclosed regarding the above-described embodiment.

[0065] (Supplementary Note 1) A film formation method comprising: a) placing a substrate on a stage inside a processing vessel, the stage being configured to support the substrate and connected to ground via a first electrical path, a conductive ring member being disposed around the stage and connected to ground via a second electrical path, and an electrode being disposed facing the stage; and b) supplying a processing gas including a carbon-containing gas into the processing vessel, while setting an impedance of the first electrical path to be higher than an impedance of the second electrical path, to supply power having a frequency equal to or lower than a VHF (Very High Frequency) band to the electrode to generate plasma in the processing vessel, and forming a graphene film on the substrate.

[0066] (Supplementary Note 2) The film forming method according to Supplementary Note 1, wherein in the step b), the impedance of the first electrical path is 10 times or more higher than the impedance of the second electrical path.

[0067] (Supplementary Note 3) The film forming method according to Supplementary Note 1 or 2, wherein in the step b), a distance between an upper surface of the stage and a lower surface of the electrode is 10 mm to 80 mm.

[0068] (Supplementary Note 4) The film forming method according to any one of Supplementary Notes 1 to 3, wherein in step b), power having a frequency between 100 kHz and 13.56 MHz is supplied to the electrode.

[0069] (Supplementary Note 5) The film forming method according to any one of Supplementary Notes 1 to 4, wherein the carbon-containing gas is a hydrocarbon gas.

[0070] (Supplementary Note 6) The film forming method according to any one of Supplementary Notes 1 to 5, wherein the processing gas contains an inert gas.

[0071] (Supplementary Note 7) The film forming method according to Supplementary Note 6, wherein the inert gas is at least one of Ar gas, He gas, N2 gas, and Kr gas.

[0072] (Supplementary Note 8) The film forming method according to any one of Supplementary Notes 1 to 7, wherein the stage is provided with a heater, and in the step b), the temperature of the substrate is adjusted to within a range of 300°C to 500°C by the heater.

[0073] (Supplementary Note 9) The film forming method according to any one of Supplementary Notes 1 to 8, wherein in the step b), the pressure inside the processing chamber is 200 mTorr to 600 mTorr.

[0074] (Supplementary Note 10) The film forming method according to any one of Supplementary Notes 1 to 9, wherein in the step b), the power of the electric power supplied to the electrode is in the range of 50 W to 1000 W.

[0075] (Supplementary Note 11) The film formation method according to any one of Supplementary Notes 1 to 10, wherein the substrate has a metal-containing film formed on a surface thereof, the metal-containing film being capable of forming graphene thereon.

[0076] (Supplementary Note 12) The film forming method according to Supplementary Note 11, wherein the metal-containing film is any one of a film of Ru, Co, Cu, W, and Mo, a film of any one of oxides thereof, and a film of any one of nitrides thereof.

[0077] (Supplementary Note 13) The film forming method according to Supplementary Note 11 or 12, further comprising the step of: c) exposing the surface of the metal-containing film to a second process gas containing a reducing gas before the step b).

[0078] (Supplementary Note 14) The film forming method according to Supplementary Note 13, wherein in the step c), a distance between an upper surface of the stage and a lower surface of the electrode is 80 mm to 130 mm.

[0079] (Supplementary Note 15) The film forming method according to Supplementary Note 13 or 14, wherein in the step c), the pressure inside the processing chamber is 50 mTorr to 2000 mTorr.

[0080] (Supplementary Note 16) The film forming method according to any one of Supplementary Notes 11 to 15, wherein the reducing gas is at least one of hydrogen gas, CO gas, and hydrocarbon gas.

[0081] (Supplementary Note 17) The film formation method according to any one of Supplementary Notes 11 to 16, wherein a distance between an upper surface of the stage and a lower surface of the electrode is configured to be changeable, and in the step c), the distance between the upper surface of the stage and the lower surface of the electrode is set to be the same as or longer than that in the step b).

[0082] (Supplementary Note 18) The film forming method according to any one of Supplementary Notes 1 to 17, further comprising the step of: d) before the step a) and the step b), supplying power to the electrode while supplying a third process gas containing an inert gas into the process vessel to remove residual oxygen from the process vessel.

[0083] (Supplementary Note 19) The film forming method according to Supplementary Note 18, wherein in the step d), a distance between an upper surface of the stage and a lower surface of the electrode is 80 mm to 130 mm.

[0084] a stage disposed inside the processing vessel, on which a substrate is placed, and connected to ground via a first electrical path; a conductive ring member disposed around the stage, and connected to ground via a second electrical path; an electrode disposed inside the processing vessel facing the stage; a gas supply unit configured to supply a processing gas into the processing vessel; a power supply configured to supply electric power of a frequency equal to or lower than a VHF (Very High Frequency) band to the electrode; and a control unit configured to control the power supply to supply electric power of a frequency equal to or lower than a VHF band to the electrode while supplying a processing gas containing a carbon-containing gas from the gas supply unit into the processing vessel.

[0085] REFERENCE SIGNS LIST 1 Plasma processing apparatus 10 Chamber 12 Chamber body 12a Side wall 12b Bottom wall 12c Opening 13 Wiring 14 Substrate support portion 15 Cover ring 16 Support member 18 Lower electrode 20 Heater 22 Heater power supply 25 Flange 26 Lifting mechanism 27 Bellows 28a Wiring 28b Wiring 30 Upper electrode 30d Gas diffusion space 32 Insulating member 33 Base member 33a Gas introduction port 34 Top plate 34a Gas hole 36 Gas supply portion 38 Piping 40 Exhaust device 44 High frequency power supply 46 Matching box 50 Impedance circuit 51 Electrical path 52 Electrical path 70 Ring electrode 80 Control unit

Claims

1. A film formation method comprising: a) placing a substrate on a stage inside a processing vessel, the stage being connected to ground via a first electrical path, a conductive ring member being arranged around the stage and connected to ground via a second electrical path, and an electrode being arranged facing the stage; and b) supplying a processing gas including a carbon-containing gas into the processing vessel, while setting the impedance of the first electrical path to a state higher than the impedance of the second electrical path, supplying power having a frequency of VHF (Very High Frequency) or lower to the electrode to generate plasma in the processing vessel, and forming a graphene film on the substrate.

2. The film forming method according to claim 1, wherein in step b), the impedance of the first electrical path is 10 times or more higher than the impedance of the second electrical path.

3. The film forming method according to claim 1 or 2, wherein in the step b), the distance between the upper surface of the stage and the lower surface of the electrode is 10 mm to 80 mm.

4. The film forming method according to claim 1, wherein in step b), power having a frequency between 100 kHz and 13.56 MHz is supplied to the electrodes.

5. The film forming method according to claim 1, wherein the carbon-containing gas is a hydrocarbon gas.

6. The film forming method according to claim 1, wherein the process gas contains an inert gas.

7. The film forming method according to claim 6, wherein the inert gas is at least one of Ar gas, He gas, N2 gas, and Kr gas.

8. The film forming method according to claim 1, wherein the stage is provided with a heater, and in the step b), the temperature of the substrate is adjusted to within a range of 300° C. to 500° C. by the heater.

9. The film forming method according to claim 1, wherein in the step b), the pressure inside the processing vessel is 200 to 600 mTorr.

10. The method according to claim 1, wherein the power of the electric power supplied to the electrode in step b) is within a range of 50 W to 1000 W.

11. The method according to claim 1, wherein the substrate has a metal-containing film on its surface on which graphene can be formed.

12. The film forming method according to claim 11, wherein the metal-containing film is any one of a Ru, Co, Cu, W, and Mo film, any one of an oxide film, and any one of a nitride film.

13. The method of claim 11 or 12, further comprising the step of: c) exposing the surface of the metal-containing film to a second process gas containing a reducing gas before the step b).

14. The film forming method according to claim 13, wherein in step c), the distance between the upper surface of the stage and the lower surface of the electrode is 80 mm to 130 mm.

15. The film forming method according to claim 13, wherein in said step c), the pressure inside said processing vessel is 50 to 2000 mTorr.

16. The film forming method according to claim 13, wherein the reducing gas is at least one of hydrogen gas, CO gas, and a hydrocarbon gas.

17. The film forming method according to claim 13, wherein the distance between the upper surface of the stage and the lower surface of the electrode is configured to be changeable, and in step c), the distance between the upper surface of the stage and the lower surface of the electrode is set to the same distance as in step b) or longer than in step b).

18. The film forming method according to claim 1, further comprising the step of: d) before step a) and step b), supplying power to the electrode while supplying a third process gas containing an inert gas into the inside of the process vessel to remove residual oxygen in the process vessel.

19. The film forming method according to claim 18, wherein in step d), the distance between the upper surface of the stage and the lower surface of the electrode is 80 mm to 130 mm.

20. A plasma processing apparatus comprising: a processing vessel; a stage disposed inside the processing vessel, on which a substrate is placed, and configured to be connected to ground via a first electrical path; a ring member having electrical conductivity, disposed around the stage, and configured to be connected to ground via a second electrical path; an electrode configured to be disposed inside the processing vessel facing the stage; a gas supply unit configured to supply a processing gas into the processing vessel; a power source configured to supply power having a frequency equal to or lower than the VHF (Very High Frequency) band to the electrode; and a control unit configured to control the power source to supply power having a frequency equal to or lower than the VHF band to the electrode while supplying a processing gas containing a carbon-containing gas from the gas supply unit into the processing vessel, with the impedance of the first electrical path being higher than the impedance of the second electrical path.

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