Film forming apparatus and film forming method

Abstract

This film forming device includes: a vacuum container in which a substrate is disposed; an antenna that generates inductively coupled plasma in the vacuum container and that includes a conductor element and a capacitor element that are electrically connected to each other in series; a high-frequency power supply that supplies high-frequency current to the antenna; and a gas supply mechanism that supplies raw material gas containing C, H, and O into the vacuum container. A carbon-based thin film is formed on the substrate in the vacuum container by a plasma CVD method using the inductively coupled plasma generated in the vacuum container by applying the high-frequency current to the antenna.

Description

[Technical Field]

[0001] The present invention relates to a film-forming apparatus and a film-forming method for forming a carbon-based thin film by plasma CVD. [Background technology]

[0002] Conventionally, known film formation devices for synthesizing carbon-based thin films such as diamond using the CVD method include filament CVD devices, microwave resonator-type plasma CVD devices, microwave surface wave plasma CVD devices, and radio frequency inductively coupled plasma (RF-ICP) CVD devices using coil electrodes (see, for example, Patent Document 1). For RF plasma, a linear antenna-type ICP plasma CVD device is also known.

[0003] The above-mentioned filament CVD device is configured to place a high-melting metal wire above the substrate on which diamond is formed, and to synthesize diamond by decomposing raw material gas with thermions emitted when this metal wire is heated.In addition, in the plasma CVD device using microwaves and the plasma CVD device using high frequency, a plasma containing raw material gas is generated by applying high frequency current, and diamond is synthesized with the activated gas.It is known that these CVD devices mainly generate active atomic hydrogen in the plasma, and by this action, non-diamond components with sp1 bond or sp2 bond are removed, and diamond components with sp3 bond can be mainly grown. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-55087 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when synthesizing diamond using the above-mentioned plasma CVD apparatus, due to the constraints of the apparatus's configuration, diamond could only be synthesized on a small area. For example, even if an attempt was made to stretch a long filament, it would break due to its own weight when heated. Furthermore, microwaves such as 2.45 GHz and 915 MHz are used, but the plasma size could not be increased due to issues with the resonant wavelength.

[0006] Furthermore, in the case of high-frequency inductive coupling using a coiled electrode, plasma nonuniformity occurred depending on the size of the coil. Furthermore, the elemental ratio of C (carbon), H (hydrogen), and O (oxygen) in the source gas is important, but conventional CVD methods have the problem of only being able to synthesize diamond with a very narrow composition range of source gas. Specifically, as shown in the Bachmann CHO diagram in Figure 9, which shows the elemental ratios of C, H, and O, diamond could only be synthesized in the range of 0.8 ≦ H / (H + C) and O / (O + H) ≦ 0.1. Furthermore, it was difficult to generate high-density plasma with a linear antenna, making it impossible to synthesize diamond.

[0007] The present invention has been made to solve the above problems, and its main object is to enable a film-forming apparatus for forming a carbon-based thin film such as diamond by a CVD method to form a carbon-based thin film using a wide range of raw material gas compositions and to enable film formation over a large area. [Means for solving the problem]

[0008] That is, the film formation apparatus according to the present invention is characterized in that it comprises a vacuum vessel in which a substrate is placed, an antenna for generating inductively coupled plasma within the vacuum vessel, the antenna having a conductor element and a capacitive element electrically connected in series with each other, a high-frequency power supply for supplying a high-frequency current to the antenna, and a gas supply mechanism for supplying a raw material gas containing C, H, and O into the vacuum vessel, and forms a carbon-based thin film on the substrate within the vacuum vessel by a plasma CVD method using the inductively coupled plasma generated within the vacuum vessel by passing a high-frequency current through the antenna.

[0009] This configuration allows for the use of inductively coupled plasma generated by a high-frequency induction field, enabling the decomposition of molecules with high binding energy, such as CO2, contained in the source gas over a wide range, thereby promoting the generation of oxygen-containing radicals. Furthermore, the inductively coupled plasma is generated using a so-called LC antenna, which has a conductor element acting as an inductor and a capacitive element acting as a capacitor, enabling long-term activation even when the source gas contains a high amount of oxygen. Alternatively, the inductively coupled plasma can be generated using a linear antenna, which has multiple linear conductor elements acting as inductors and a capacitive element acting as a capacitor connected in series between them. Here, the capacitive element acting as a capacitor refers to a capacitive element other than a matching box. This allows for the formation of carbon-based thin films, such as diamond, using a wide range of source gas compositions, which was not possible with conventional CVD systems, and also allows for the formation of carbon-based thin films over larger areas than with conventional plasma CVD systems.

[0010] The composition range of the source gas supplied by the gas supply mechanism is preferably such that the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms is 10 at % or more and 60 at % or less. The film deposition apparatus of the present invention described above can form a carbon-based thin film even when the source gas has such a composition range.

[0011] Furthermore, in the film forming apparatus, it is preferable that the gas supply mechanism supplies Ar gas into the vacuum chamber together with the raw material gas, and that the ratio of the flow rate of the Ar gas to the total flow rate of all gases supplied into the vacuum chamber is 50% or more and 90% or less. By supplying Ar gas together with the source gas, the easily ionized Ar acts as a catalyst to promote the decomposition of the source gas. This broadens the range of source gas compositions that can form carbon-based thin films. This effect becomes more pronounced when the flow rate of Ar gas is between 50% and 90%.

[0012] In the film forming apparatus, it is preferable that the emission spectrum of the inductively coupled plasma has a ratio of the emission intensity of C2 radicals to the emission intensity of Hα radicals of 30% or more and 300% or less. If the ratio of the C2 radical emission intensity to the Hα radical emission intensity is less than 30%, etching will occur more than film synthesis, and nucleation may not occur.On the other hand, if the ratio of the C2 radical emission intensity to the Hα radical emission intensity is more than 300%, non-diamond components will increase, and graphite or DLC films may result.

[0013] The pressure inside the vacuum chamber during film formation is preferably 7 Pa or more and 100 Pa or less. If the pressure inside the vacuum chamber during film formation is less than 7 Pa, the synthesized film may be subjected to strong ion bombardment, resulting in a graphite film. On the other hand, if the pressure inside the vacuum chamber during film formation is more than 100 Pa, plasma may concentrate around the antenna, making it impossible to synthesize a carbon-based thin film.

[0014] In a specific embodiment of the thin film device, the carbon-based thin film is a diamond film.

[0015] Furthermore, the film formation method of the present invention is characterized in that a source gas containing C, H, and O is supplied into a vacuum vessel in which a substrate is placed, an antenna is placed inside or outside the vacuum vessel, and the antenna has a conductor element and a capacitive element electrically connected in series with each other, thereby generating inductively coupled plasma in the vacuum vessel, and a carbon-based thin film is formed on the substrate by a plasma CVD method using the generated inductively coupled plasma.

[0016] The film forming method configured in this manner can achieve the same effects as the film forming apparatus of the present invention described above. [Effects of the Invention]

[0017] According to the present invention configured as described above, in a film formation apparatus for forming a carbon-based thin film such as diamond by a CVD method, it is possible to form a carbon-based thin film using a source gas with a wide composition range, and further, it is possible to form a film over a large area. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram schematically illustrating the configuration of a film forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the gas composition range of source gases supplied in the film formation apparatus and the first film formation method according to the embodiment. [Figure 3] FIG. 10 is a graph showing the relationship between the ratio of Ar gas supplied and the emission intensity ratio of C2 radicals to Hα radicals in the generated plasma. [Figure 4] FIG. 10 is a diagram showing the gas composition range of the source gas supplied in the second film formation method. [Figure 5] FIG. 2 is a diagram showing the gas composition and pressure during film formation of each sample synthesized in Example 1. [Figure 6] FIG. 2 shows the Raman scattering spectra of the samples synthesized in Example 1. [Figure 7] FIG. 10 is a diagram showing the gas composition and pressure during film formation of each sample synthesized in Example 2. [Figure 8] FIG. 1 shows the Raman scattering spectra of the samples synthesized in Example 2. [Figure 9] FIG. 1 is a diagram showing the composition range of source gases that can synthesize diamond using a conventional CVD method. DETAILED DESCRIPTION OF THE INVENTION

[0019] A film forming apparatus and a film forming method according to an embodiment of the present invention will be described below with reference to the drawings.

[0020] <1.Device configuration> The film forming apparatus 100 of this embodiment is a plasma CVD apparatus that forms a carbon-based thin film on a substrate W by a plasma CVD method using an inductively coupled plasma P. Here, the carbon-based thin film is, for example, a diamond film, a diamond-like carbon (DLC) film, or the like.

[0021] The substrate W in this embodiment is a plate-shaped substrate made of a material suitable for forming a carbon-based thin film, such as, but not limited to, glass, plastic, silicon, iron, titanium, copper, metals such as cemented carbide, other alloy materials such as tool steel, SiC, GaN, AlN, BN, diamond, etc.

[0022] The substrate W has a rectangular or circular shape in a plan view. The length of the substrate W can be, for example, 20 cm or more or 50 cm or more, but is not limited to these. The substrate W may also be, for example, a plurality of small chip-shaped substrates of about 1 mm, 5 mm, or 10 mm arranged with the same length or area. The substrate W is not limited to a plate shape, and may also be columnar, perforated, or porous. It may also have a complex shape, such as a tool such as a drill or end mill.

[0023] The substrate W may also be subjected to a surface treatment such as a scratching treatment or a seeding treatment. For example, if the substrate W is silicon, it may be immersed in alcohol together with diamond fine particles and subjected to a scratching treatment or a seeding treatment in which unevenness is formed on the surface by ultrasonic treatment. For example, if the substrate W is a cemented carbide alloy, it may be immersed in an acidic solution such as a nitric acid solution to remove Co from the substrate, or the surface of tungsten carbide (WC) particles may be treated with an alkaline solution such as diluted NaOH, followed by the above-mentioned seeding treatment.

[0024] 1, the film formation apparatus 100 includes a vacuum vessel 2 that is evacuated and into which a gas G is introduced, a gas supply mechanism 7 that supplies the gas G to the vacuum vessel 2, a linear antenna 3 disposed within the vacuum vessel 2, and a high-frequency power supply 4 that applies high-frequency waves to the antenna 3 to generate an inductively coupled plasma P within the vacuum vessel 2. In this film formation apparatus 100, by applying high-frequency waves from the high-frequency power supply 4 to the antenna 3, a high-frequency current IR flows through the antenna 3, an inductive electric field is generated within the vacuum vessel 2, and the inductively coupled plasma P is generated.

[0025] The vacuum vessel 2 is a vessel made of metal such as SUS or aluminum, and its interior is evacuated to a vacuum by a vacuum exhaust device 6. In this example, the vacuum vessel 2 is electrically grounded. The vacuum exhaust device 6 is equipped with a pressure regulator 61 such as a valve that adjusts the pressure inside the vacuum vessel 2. By controlling this pressure regulator 61, the pressure inside the vacuum vessel 2 during plasma generation can be adjusted, for example, to a pressure of 7 Pa or more and 100 Pa or less.

[0026] Gas G such as a source gas is introduced into the vacuum chamber 2 via a flow rate regulator (not shown) and a plurality of gas inlets 21 arranged in a direction along the antenna 3, for example.

[0027] A substrate holder 8 for holding the substrate W is provided within the vacuum chamber 2, and a heater 81 for heating the substrate W is provided within the substrate holder 8. The substrate holder 8 does not necessarily have to be electrically connected to the vacuum chamber 2. The film forming apparatus 100 of this embodiment may have a function of adjusting the potential of the generated inductively coupled plasma, for example, within a range of +100 V to −100 V, by applying a bias voltage from a bias power supply 9 to the substrate holder 8. The applied bias voltage is, for example, a negative DC voltage, but is not limited to this. Such a bias voltage can, for example, control the energy of positive ions in the plasma P when they are incident on the substrate W, thereby controlling the crystallinity of the film formed on the surface of the substrate W.

[0028] The gas supply mechanism 7 supplies gas G, such as a source gas, into the vacuum vessel 2 through a gas inlet 21. The gas supply mechanism 7 is configured to supply gas G downward from the gas inlet 21 provided on the upper wall of the vacuum vessel 2. The gas supply mechanism 7 is configured to supply a source gas containing at least C (carbon), H (hydrogen), and O (oxygen), and more specifically, is configured to supply H gas, CH gas, and CO gas as the source gas. Note that the gas supply mechanism 7 may be configured to supply any other gas as the source gas in addition to or instead of H gas, CH gas, and CO gas, as long as it is configured to supply a source gas containing C, H, and O into the vacuum vessel 2.

[0029] The gas supply mechanism 7 is configured to supply H gas, CH gas, and CO gas at any flow rate. The gas supply mechanism 7 of this embodiment is configured to adjust the flow rate of each gas so that the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms (O / (O+H)) in the source gas containing H gas, CH gas, and CO gas is, for example, 10 at % or more and 60 at % or less.

[0030] The gas supply mechanism 7 is also configured to supply a catalyst gas into the vacuum chamber 2 at a desired flow rate along with the raw material gas. This catalyst gas functions as a catalyst during plasma generation and promotes the decomposition of the raw material gas. Specifically, the gas supply mechanism 7 is configured to supply the catalyst gas so that the proportion of the catalyst gas to the total flow rate of all gases supplied into the vacuum chamber 2 (here, the total flow rate of the raw material gas and the catalyst gas) is, for example, 50% to 90%, preferably 75% to 90%. Specific examples of this catalyst gas include rare gases such as Ar gas, He gas, and Ne gas.

[0031] The antenna 3 is disposed above the substrate W in the vacuum chamber 2, along the surface of the substrate W. In this embodiment, a plurality of linear antennas 3 are disposed in parallel along the substrate W (for example, substantially parallel to the surface of the substrate W). In this manner, plasma P with good uniformity can be generated over a wider range, and therefore larger substrates W can be processed.

[0032] The number of antennas 3 is not limited to multiple and may be only one. When multiple antennas 3 are provided, the number is preferably an even number (for example, 2, 4, 6, etc.). When multiple antennas 3 are provided, the spacing between each antenna 3 is preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 15 cm or more, to avoid radio wave interference. On the other hand, to form a uniform carbon-based thin film, the spacing between the antennas 3 is preferably 25 cm or less. When multiple antennas 3 are provided, the antennas 3 are preferably arranged parallel to each other and on the same plane, and the plane enclosed by the antennas 3 at both ends is preferably arranged in a square or rectangular shape (preferably with one side of 40 cm or more). More preferably, one side is 50 cm or more, even more preferably, one side is 70 cm or more, and even more preferably, one side is 100 cm or more.

[0033] As shown in FIG. 1 , the vicinity of both ends of the antenna 3 penetrates a pair of opposing side walls 2a, 2b of the vacuum vessel 2. Insulating members 11 are provided at the portions where both ends of the antenna 3 penetrate to the outside of the vacuum vessel 2. Both ends of the antenna 3 penetrate each insulating member 11, and the penetration portions are vacuum-sealed by, for example, packing 12. The antenna 3 is supported via the insulating members 11 in a state where it is electrically insulated from the opposing side walls 2a, 2b of the vacuum vessel 2. The gap between each insulating member 11 and the vacuum vessel 2 is also vacuum-sealed by, for example, packing 13. The insulating members 11 are made of a material such as ceramics, such as alumina, quartz, or engineering plastics, such as polyphenylene sulfide (PPS) or polyether ether ketone (PEEK).

[0034] The antenna 3 is a so-called LC antenna that includes an L portion that serves as an inductor and a C portion that serves as a capacitor. Specifically, the antenna 3 includes at least two tubular metal conductor elements 31 (hereinafter referred to as metal pipes 31), a tubular insulating element 32 (hereinafter referred to as insulating pipe 32) that is provided between adjacent metal pipes 31 and insulates the metal pipes 31, and a capacitor 33 that is a capacitive element that is provided between adjacent metal pipes 31 and electrically connected in series with them. The conductor elements 31 function as the L portion, and the capacitor 33 functions as the C portion.

[0035] In this embodiment, the number of metal pipes 31 is three, and the number of insulating pipes 32 and capacitors 33 is two each. Note that the antenna 3 may be configured to have four or more metal pipes 31, in which case the number of insulating pipes 32 and capacitors 33 will each be one less than the number of metal pipes 31.

[0036] The material of the metal pipe 31 is, for example, but not limited to, copper, aluminum, an alloy thereof, stainless steel, etc. The antenna 3 may be hollow and a refrigerant such as cooling water may be passed through it to cool the antenna 3.

[0037] In this embodiment, the insulating pipe 32 is formed from a single member, but is not limited to this. The insulating pipe 32 may be made of a material such as alumina, fluororesin, polyethylene (PE), or engineering plastic (such as polyphenylene sulfide (PPS) or polyether ether ketone (PEEK)).

[0038] Furthermore, the portion of the antenna 3 located inside the vacuum vessel 2 is covered by a straight tubular insulating cover (antenna protection tube) 10. Both ends of this insulating cover 10 are supported by insulating members 11. Note that it is not necessary to seal between both ends of the insulating cover 10 and the insulating members 11. This is because even if gas G enters the space inside the insulating cover 10, the space is small and the travel distance of electrons is short, so plasma P is not normally generated in the space. Note that the insulating cover 10 can be made of a material such as quartz, alumina, fluororesin, silicon nitride, silicon carbide, or silicon.

[0039] By providing the insulating cover 10, it is possible to prevent charged particles in the plasma P from entering the metal pipe 31 that constitutes the antenna 3, thereby preventing an increase in plasma potential due to charged particles (mainly electrons) entering the metal pipe 31 and also preventing the metal pipe 31 from being sputtered by charged particles (mainly ions), resulting in metal contamination of the plasma P and the substrate W.

[0040] The length of the antenna 3 is, for example, preferably 20 cm or more, more preferably 50 cm or more, and even more preferably 100 cm or more. On the other hand, from the viewpoint of ensuring the strength of the insulating pipe 32, the length of the antenna 3 is preferably 1000 cm or less, and more preferably 500 cm or less.

[0041] 1, the antenna 3 has a power feeding end 3a to which high frequency power is fed in the antenna direction (longitudinal direction X) and a grounded end 3b. Specifically, at both ends of each antenna 3 in the longitudinal direction X, the portion extending outward from one of the side walls 2a or 2b serves as the power feeding end 3a, and the portion extending outward from the other of the side walls 2a or 2b serves as the grounded end 3b.

[0042] Here, a high frequency is applied to the power feeding end 3a of each antenna 3 from a high frequency power supply 4 via a matching box 41. The frequency of the high frequency is 400 kHz or more and 100 MHz or less, for example, the common frequency of 13.56 MHz, but is not limited to this. For example, it may be 27.12 MHz, 40.68 MHz, 60 MHz, etc.

[0043] <2. Film formation method> Next, a description will be given of a method for forming a carbon-based thin film using the above-described film formation apparatus 100. Below, a first film formation method and a second film formation method, which differ in the composition ratio of the raw material gases supplied, will be described. With the above-described film formation apparatus 100, a carbon-based thin film such as diamond can be formed by either film formation method.

[0044] (First film formation method) First, the substrate W is placed on the substrate holder 8 in the vacuum chamber 2 of the film formation apparatus 100, and the vacuum chamber 2 is evacuated using the vacuum pumping device 6. The substrate W is heated using the heater 81, and the temperature of the substrate W is preferably set to 100°C or higher and 1200°C or lower. The temperature range of the substrate W may be changed depending on the particle size and crystallinity of the diamond to be synthesized. In the first film formation method, for example, when synthesizing a carbon-based thin film containing diamond microcrystals in the DLC film, the temperature of the substrate W is preferably set to 100°C or higher and 400°C or lower. When synthesizing a carbon-based thin film containing diamond with a particle size of 200 nm or less, the temperature of the substrate W is preferably set to 200°C or higher and lower than 500°C. When synthesizing a carbon-based thin film containing diamond with a particle size of 200 nm or less and 1000 nm or less, the temperature of the substrate W is preferably set to 200°C or higher and lower than 500°C. When synthesizing a carbon-based thin film containing diamond with a particle size of 200 nm or more and 1000 nm or less, the temperature of the substrate W is preferably set to 700°C or higher and 1200°C or lower.

[0045] (Supply of raw gas) Next, the gas supply mechanism 7 supplies H2 gas, CH4 gas, and CO2 gas as source gases into the vacuum chamber 2 at predetermined flow rates. In the film formation method of this embodiment, the flow rates of H2 gas, CH4 gas, and CO2 gas are adjusted so that the atomic ratios of O atoms, C atoms, and H atoms in the source gases fall within the shaded range shown in the composition ternary diagram (C-H-O diagram) in Figure 2. The atomic ratios of each atom are described below.

[0046] (ratio of oxygen and hydrogen atoms) The flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained in the source gas to be supplied (O / (O+H)) is preferably 10 at % or more and 60 at % or less, more preferably 30 at % or more and 50 at % or less.

[0047] (ratio of oxygen to carbon atoms) The flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms (C / (O+C)) in the source gas to be supplied is preferably 30 at % or more and 45 at % or less, more preferably 35 at % or more and 45 at % or less.

[0048] (ratio of carbon to hydrogen atoms) Furthermore, the flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms (H / (C+H)) in the source gas to be supplied is preferably 40 at % or more and 90 at % or less, more preferably 50 at % or more and 80 at % or less.

[0049] (Catalyst gas supply) Furthermore, a catalyst gas such as Ar gas is supplied into the vacuum chamber together with the source gas by the gas supply mechanism 7. The flow rate of the catalyst gas to be supplied is preferably set to 50% to 90%, more preferably 75% to 90%, of the total flow rate of all gases supplied to the vacuum chamber 2. By setting the flow rate of the catalyst gas to this range, energy can be transferred from easily ionized elements such as Ar to CH4 during film formation, generating a large amount of C2 radicals, which are likely to produce diamond. As a result, as shown in Figure 3, the ratio of the emission intensity of C2 radicals to the emission intensity of Hα radicals in the emission spectrum of the generated inductively coupled plasma can be set to 30% to 300%, more preferably 90% to 250%.

[0050] (Pressure inside the vacuum vessel) Then, while the raw material gas and catalyst gas are introduced by the gas supply mechanism 7, the pressure inside the vacuum chamber 2 is adjusted by the pressure regulator 61 to 7 Pa or more and 100 Pa or less, more preferably 10 Pa or more and 50 Pa or less.

[0051] (Plasma generation and carbon-based thin film deposition) Then, with the flow rates of the raw material gas and catalyst gas adjusted as described above and the pressure inside the vacuum chamber 2 adjusted, high-frequency power is supplied from the high-frequency power supply 4 to the antenna 3. This generates an inductive electric field inside the vacuum chamber 2, generating an inductively coupled plasma P, which forms a carbon-based thin film on the substrate W. The frequency of the high-frequency power is 400 kHz or more and 100 MHz or less, and is preferably 13.56 MHz, for example. The power density of the supplied high-frequency power is 0.1 W / cm. 2 More than 0.5W / cm is preferable. 2 More preferably, 1 W / cm 2 More preferably, the power density is 1000W / cm. 2 Less than 100W / cm is preferable. 2 Less than 50W / cm is more preferable. 2 The following is even more preferred:

[0052] (Second film forming method) Next, we will explain the second film formation method, which differs from the first film formation method in the gas composition ratio of the supplied raw material gas. First, the substrate W is placed on the substrate holder 8 inside the vacuum chamber 2 of the film formation apparatus 100, and the vacuum chamber 2 is evacuated using the vacuum exhaust device 6. The substrate W is heated using the heater 81, and the temperature of the substrate W is preferably set to 100°C or higher and 1200°C or lower. The temperature range of the substrate W may be changed depending on the particle size and crystallinity of the diamond to be synthesized. In the second film formation method, when synthesizing a carbon-based thin film containing diamonds with a particle size of 50 nm or less, the supplied raw material gas is preferably hydrogen-rich and the temperature of the substrate W is preferably set to 500°C or higher and 1200°C or lower. When synthesizing a carbon-based thin film containing diamonds with a particle size of 10 nm or less, the supplied raw material gas is preferably oxygen-rich and the temperature of the substrate W is preferably set to 800°C or lower.

[0053] (Supply of raw gas) Next, the gas supply mechanism 7 supplies H gas, CH gas, and CO gas as source gases at predetermined flow rates into the vacuum chamber 2. In the film formation method of this embodiment, the flow rates of H gas, CH gas, and CO gas are adjusted so that the atomic ratios of O atoms, C atoms, and H atoms in the source gases fall within the shaded range shown in the composition ternary diagram (C-H-O diagram) of Figure 4. The atomic ratios of each atom are described below.

[0054] (ratio of oxygen and hydrogen atoms) The flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained in the source gas to be supplied (O / (O+H)) is preferably 5 at % or more and 45 at % or less, more preferably 5 at % or more and 10 at % or less.

[0055] (ratio of oxygen to carbon atoms) The flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms (C / (O+C)) in the source gas to be supplied is preferably 45 at % or more and 70 at % or less.

[0056] (ratio of carbon to hydrogen atoms) Furthermore, the flow rates of H gas, CH gas, and CO gas are controlled so that the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms (H / (C+H)) in the source gas to be supplied is preferably 60 at % or more and 95 at % or less, more preferably 90 at % or more and 95 at % or less.

[0057] (Catalyst gas supply) Furthermore, a catalytic gas such as Ar gas is supplied into the vacuum chamber together with the source gas by the gas supply mechanism 7. The flow rate of the supplied catalytic gas is set so that the ratio of the total flow rate of all gases supplied to the vacuum chamber 2 is preferably 50% to 95%, more preferably 70% to 90%. By setting the flow rate of the supplied catalytic gas within this range, the ratio of the emission intensity of C2 radicals to the emission intensity of Hα radicals in the emission spectrum of the generated inductively coupled plasma can be set to 30% to 300%, more preferably 90% to 250%.

[0058] (Pressure inside the vacuum vessel) Then, while the raw material gas and catalyst gas are introduced by the gas supply mechanism 7, the pressure inside the vacuum chamber 2 is adjusted by the pressure regulator 61 to 7 Pa or more and 100 Pa or less, more preferably 10 Pa or more and 50 Pa or less.

[0059] (Plasma generation and carbon-based thin film deposition) Then, with the flow rates of the raw material gas and catalyst gas adjusted as described above and the pressure inside the vacuum chamber 2 adjusted, high-frequency power is supplied from the high-frequency power supply 4 to the antenna 3. This generates an inductive electric field inside the vacuum chamber 2, generating an inductively coupled plasma P, which forms a carbon-based thin film on the substrate W. The frequency of the high-frequency power is 400 kHz or more and 100 MHz or less, and is preferably 13.56 MHz, for example. The power density of the supplied high-frequency power is 0.1 W / cm. 2 More than 0.5W / cm is preferable. 2 More preferably, 1 W / cm 2More preferably, the power density is 1000W / cm. 2 Less than 100W / cm is preferable. 2 Less than 50W / cm is more preferable. 2 The following is even more preferred:

[0060] <3. Effects of this embodiment> The film formation apparatus 100 and film formation method of this embodiment, configured as described above, use inductively coupled plasma P generated by a high-frequency induction field, enabling decomposition of molecules with high binding energy, such as CO2, contained in the source gas over a wide range, thereby promoting the generation of oxygen-containing radicals. Furthermore, since the inductively coupled plasma is generated by the antenna 3, activation can be maintained for a long period of time, even if the source gas has a gas composition containing a large amount of oxygen. This makes it possible to form carbon-based thin films, such as diamond, using a wide range of source gas compositions that could not be achieved using conventional CVD apparatuses, and furthermore, it is possible to form carbon-based thin films with a larger area than conventional plasma CVD apparatuses. Furthermore, the introduction of Ar gas as a catalytic gas can also promote the generation of C2 radicals. These C2 radicals and other radicals form a film on the substrate W, and oxygen-containing radicals and hydrogen radicals remove non-diamond components, making it easier to form a carbon-based thin film such as diamond on the substrate W.

[0061] Furthermore, according to the film forming apparatus 100 and the film forming method of the present embodiment, when Raman spectroscopy was performed with excitation at 325 nm, -1 The diamond peak intensity around 1550 cm -1 It is possible to form a diamond film having a peak intensity of more than 20%, preferably 100% or more, and more preferably 1000% or more of the G band in the vicinity.

[0062] The film forming apparatus 100 of the present invention is not limited to the above embodiment. For example, in the film formation apparatus 100 of the above embodiment, the antenna 3 that generates the inductively coupled plasma is disposed inside the vacuum chamber 2, but this is not limiting. In other embodiments, the film formation apparatus 100 may have a structure in which the antenna 3 is disposed outside the vacuum chamber 2.

[0063] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, it will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following aspects.

[0064] (Mode 1) A film formation device comprising: a vacuum vessel in which a substrate is placed; an antenna for generating inductively coupled plasma within the vacuum vessel, the antenna having a conductor element and a capacitive element electrically connected in series with each other; a high-frequency power supply for supplying high-frequency current to the antenna; and a gas supply mechanism for supplying a raw material gas containing C, H, and O into the vacuum vessel, the film formation device forming a carbon-based thin film on the substrate within the vacuum vessel by a plasma CVD method using the inductively coupled plasma generated within the vacuum vessel by passing a high-frequency current through the antenna.

[0065] (Aspect 2) The film forming apparatus according to aspect 1, wherein the source gas supplied by the gas supply mechanism has a composition in which the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms is 10 at % or more and 60 at % or less.

[0066] (Aspect 3) A film formation apparatus according to aspect 1 or 2, wherein the gas supply mechanism supplies a catalyst gas into the vacuum chamber together with the raw material gas, and the ratio of the flow rate of the catalyst gas to the total flow rate of all gases supplied into the vacuum chamber is 50% or more and 90% or less.

[0067] (Aspect 4) The film forming apparatus according to aspect 3, wherein the catalytic gas is Ar gas.

[0068] (Aspect 5) The film formation apparatus according to any one of aspects 1 to 4, wherein the emission spectrum of the inductively coupled plasma has a ratio of the emission intensity of C2 radicals to the emission intensity of Hα radicals of 30% to 300%.

[0069] (Aspect 6) The film formation apparatus according to any one of Aspects 1 to 5, wherein the pressure inside the vacuum chamber during film formation is 7 Pa or more and 100 Pa or less.

[0070] (Aspect 7) The film deposition apparatus according to any one of aspects 1 to 6, wherein the antenna is linear and has a length of 20 cm or more.

[0071] (Aspect 8) The film deposition apparatus according to any one of Aspects 1 to 5, wherein the carbon-based thin film is a diamond film.

[0072] (Aspect 9) The diamond film has a Raman spectrum of 1333 cm -1 The diamond peak intensity around 1550 cm -1 9. The film forming apparatus according to any one of aspects 1 to 8, wherein the peak intensity of the G band in the vicinity of the peak intensity of the G band is more than 20%.

[0073] (Aspect 10) A film formation method comprising: supplying a source gas containing C, H, and O into a vacuum vessel in which a substrate is placed; generating inductively coupled plasma in the vacuum vessel by passing a high-frequency current through an antenna placed inside or outside the vacuum vessel, the antenna having a conductor element and a capacitance element electrically connected in series with each other; and forming a carbon-based thin film on the substrate by a plasma CVD method using the generated inductively coupled plasma.

[0074] (Embodiment 11) The carbon-based thin film is a diamond film, and the diamond film has a Raman spectrum of 1333 cm in Raman spectroscopy with 325 nm excitation. -1 The diamond peak intensity around 1550 cm -1 11. The method of forming a film according to claim 10, wherein the peak intensity of the G band in the vicinity of the SiO 2 film is more than 20% of the peak intensity of the G band in the vicinity of the SiO 2 film.

[0075] <4. Example> The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and modifications can be made within the scope of the above and below-described aims, and all such modifications are within the technical scope of the present invention.

[0076] Example 1 In Example 1, a number of samples (No. 1 to No. 10) were deposited on substrates by the plasma CVD method using the above-described film deposition apparatus 100, with the composition of the source gas, the pressure in the vacuum chamber 2, and the flow rate ratio of Ar gas being varied. Sample No. 11 was also deposited on a substrate using a film deposition apparatus that uses a simple linear antenna that is not an LC antenna (i.e., does not have a capacitor). The flow rates of the source gases, the composition of the source gases, the flow rate ratio of Ar gas, and the pressure in the vacuum chamber 2 during film deposition for each sample are as shown in FIG. 5. Other film deposition conditions were as follows: Frequency of supplied high frequency power: 13.56MHz Power density of supplied high frequency power: 1.4W / cm 2 ·Substrate temperature: 500℃

[0077] The crystallinity of each sample was evaluated by laser Raman spectroscopy (325 nm excitation). The Raman scattering spectrum obtained for each sample is shown in Figure 6. As shown in Figure 6, for samples No. 1 to No. 4, in which an LC antenna was used, the ratio of the O atom concentration to the total concentration of O atoms and H atoms in the source gas was 10 at% or more and 60 at% or less, the flow rate ratio of Ar gas in the total gas was 50% or more and 90% or less, and the pressure in the vacuum chamber 2 was 7 Pa or more and 100 Pa or less, the crystallinity of each sample was evaluated by laser Raman spectroscopy (325 nm excitation). The Raman scattering spectrum obtained for each sample is shown in Figure 6. -1 The optical phonon peak of diamond was observed in the vicinity of the wavelength of , and it was confirmed that diamond could be deposited.

[0078] Example 2 In Example 2, a number of samples (No. 12 to No. 15) were deposited on substrates by the plasma CVD method using the above-described film deposition apparatus 100, while varying the source gas composition, the pressure in the vacuum chamber 2, and the Ar gas flow rate ratio. The source gas flow rate, source gas composition, Ar gas flow rate ratio, and pressure in the vacuum chamber 2 during film deposition for each sample are as shown in FIG. 7. Other film deposition conditions were as follows: Frequency of supplied high frequency power: 13.56MHz Power density of supplied high frequency power: 1.4W / cm 2 ·Substrate temperature: 500℃

[0079] The crystallinity of each sample thus formed was evaluated by laser Raman spectroscopy (325 nm excitation). The Raman scattering spectrum obtained for each sample is shown in FIG. 8. As shown in FIG. 8, in samples No. 12 to No. 15 in which an LC antenna was used and the source gas had a ratio of O atom concentration to the total concentration of O atoms and H atoms of 5 at% to 45 at%; a ratio of C atom concentration to the total concentration of O atoms and C atoms of 45 at% to 70 at%; a ratio of H atom concentration to the total concentration of C atoms and H atoms of 60 at% to 95 at%; a flow rate ratio of Ar gas to the total gas of 50% to 95%; and a pressure in the vacuum chamber 2 of 7 Pa to 100 Pa (specifically, 15 Pa), the crystallinity of each sample was evaluated by laser Raman spectroscopy (325 nm excitation). The Raman scattering spectrum obtained for each sample was shown in FIG. 8. -1 The optical phonon peak of diamond was observed in the vicinity of the wavelength of , and it was confirmed that diamond could be deposited. [Industrial Applicability]

[0080] According to the present invention, in a film-forming apparatus for forming a carbon-based thin film such as diamond by CVD, it is possible to form a carbon-based thin film using a source gas with a wide composition range, and further, it is possible to form a film over a large area. [Explanation of symbols]

[0081] 100 Plasma CVD equipment 2...Vacuum container 3. Antenna 7. Gas supply mechanism W...Base material P...Plasma

Claims

1. a vacuum vessel in which the substrate is placed; an antenna for generating inductively coupled plasma within the vacuum vessel, the antenna having a conductor element and a capacitive element electrically connected in series with each other; a high frequency power source that supplies a high frequency current to the antenna; a gas supply mechanism for supplying a source gas containing C, H, and O into the vacuum chamber; A film formation apparatus for forming a carbon-based thin film on the substrate in the vacuum chamber by a plasma CVD method using inductively coupled plasma generated in the vacuum chamber by passing a high-frequency current through the antenna while the raw material gas is being supplied into the vacuum chamber.

2. 2. The film forming apparatus according to claim 1, wherein the source gas supplied by the gas supply mechanism has a composition in which the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms is 10 at % or more and 60 at % or less.

3. 2. The film forming apparatus according to claim 1, wherein the gas supply mechanism supplies a catalyst gas into the vacuum chamber together with the raw material gas, and the ratio of the flow rate of the catalyst gas to the total flow rate of all gases supplied into the vacuum chamber is 50% or more and 90% or less.

4. 4. The film forming apparatus according to claim 3, wherein the catalytic gas is Ar gas.

5. The emission spectrum of the inductively coupled plasma is a function of the emission intensity of Hα radicals and C ２ 2. The film forming apparatus according to claim 1, wherein the ratio of the emission intensity of radicals is 30% or more and 300% or less.

6. 2. The film forming apparatus according to claim 1, wherein the pressure inside the vacuum chamber during film formation is 7 Pa or more and 100 Pa or less.

7. 2. The film deposition apparatus according to claim 1, wherein the antenna is linear and has a length of 20 cm or more.

8. 2. The film deposition apparatus according to claim 1, wherein the carbon-based thin film is a diamond film.

9. The diamond film exhibited a Raman spectrum of 1333 cm －１ The diamond peak intensity around 1550 cm －１ The film forming apparatus according to claim 8 , wherein the peak intensity of the G band is more than 20% of the peak intensity of the G band in the vicinity of the G band.

10. A source gas containing C, H, and O is supplied into a vacuum chamber in which a substrate is placed; an antenna disposed inside or outside the vacuum vessel, the antenna having a conductor element and a capacitive element electrically connected in series with each other, and a high-frequency current is passed through the antenna to generate inductively coupled plasma within the vacuum vessel; A film forming method for forming a carbon-based thin film on the substrate by a plasma CVD method using the generated inductively coupled plasma.

11. The carbon-based thin film is a diamond film, and the diamond film has a Raman spectrum of 1333 cm in Raman spectroscopy with 325 nm excitation. －１ The diamond peak intensity around 1550 cm －１ The film forming method according to claim 10, wherein the peak intensity of the G band is more than 20% of the peak intensity of the G band in the vicinity of the G band.

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