Film forming device 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 eleme

Description

Film forming apparatus and film forming method

[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.

[0002] Conventionally, known deposition 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) type plasma 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] Above-mentioned filament CVD device is configured to place a high-melting metal wire above the substrate that forms diamond, and when this metal wire is heated, the thermoelectrons that are emitted decompose raw material gas to synthesize diamond.In addition, in the plasma CVD device that uses microwave or the plasma CVD device that uses high frequency, the plasma that contains raw material gas is generated by applying high frequency current, and diamond is synthesized by the activated gas.It is known that these CVD devices mainly generate active atomic hydrogen in plasma, and by this action, the non-diamond components of sp1 bond or sp2 bond are removed, and can mainly grow the diamond components of sp3 bond.

[0004] Japanese Patent Application Laid-Open No. 2003-55087

[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 in a small area. For example, even if a long filament was tried to be stretched, it would not be able to withstand its own weight when heated and would break. Furthermore, microwaves such as 2.45 GHz and 915 MHz are used, but the plasma size could not be increased due to the problem of resonance wavelength.

[0006] In addition, in the case of high-frequency induction coupling using a coiled electrode, the size of the coil causes non-uniformity of plasma.In addition, the element ratio of C (carbon), H (hydrogen), and O (oxygen) in the raw material gas is important, but the conventional CVD method has the problem that diamond can only be synthesized with a very narrow composition range of raw material gas.Specifically, as shown in the Bachmann CHO diagram in Figure 9 showing the element ratio of C, H, and O, diamond can only be synthesized in the range of 0.8≦H / (H+C) and O / (O+H)≦0.1.In addition, it is difficult to generate high-density plasma with a linear antenna, so diamond cannot be synthesized.

[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 CVD to form a carbon-based thin film using a wide range of source gas compositions and to enable film formation over a large area.

[0008] That is, the film formation apparatus according to the present invention 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 is characterized in that a carbon-based thin film is formed 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] In this configuration, by using an inductively coupled plasma generated by a high-frequency induction electric field, CO, a molecule with high binding energy contained in the source gas, can be easily removed. ２This enables decomposition of a wide range of compounds, such as oxygen-containing radicals, and promotes the generation of oxygen-containing radicals. Furthermore, since the inductively coupled plasma is generated using a so-called LC antenna having a conductor element serving as an inductor and a capacitive element serving as a capacitor, long-term activation is possible even when the source gas has a high oxygen content. Alternatively, the inductively coupled plasma may be generated using a linear antenna having multiple linear conductor elements serving as inductors and capacitive elements serving as capacitors connected in series between them. Here, the capacitive element serving as a capacitor refers to a capacitive element other than a matching box. This makes it possible to form carbon-based thin films such as diamond using a wide range of source gas compositions, which was not possible with conventional CVD apparatuses, and also enables the formation of carbon-based thin films with a larger area than with conventional plasma CVD apparatuses.

[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 can form a carbon-based thin film even with such a composition range of the source gas.

[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 source 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, Ar, which is easily ionized, can act as a catalyst to promote decomposition of the source gas. This makes it possible to broaden the composition range of the source gas that can form a carbon-based thin film. This effect becomes more pronounced when the flow rate of Ar gas is 50% or more and 90% or less.

[0012] In the film forming apparatus, the emission spectrum of the inductively coupled plasma is expressed as C ２ It is preferable that the ratio of the emission intensity of the radical is 30% or more and 300% or less. ２If the ratio of the radical emission intensity is less than 30%, etching will be more severe than film synthesis, and nucleation may not occur. ２ If the ratio of radical emission intensity exceeds 300%, the amount of non-diamond components increases, and there is a risk of graphite or DLC film being formed.

[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 be concentrated 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 raw material 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.

[0017] According to the present invention configured as described above, 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 moreover, it is possible to form a film over a large area.

[0018] 1 is a diagram showing a schematic configuration of a film formation apparatus according to an embodiment of the present invention, and a diagram showing a gas composition range of a source gas supplied in the film formation apparatus and a first film formation method of the embodiment, which shows a ratio of Ar gas supplied and C in the generated plasma. ２FIG. 1 is a diagram showing the relationship between the emission intensity ratio of radicals and Hα radicals. FIG. 2 is a diagram showing the gas composition range of the raw material gas supplied in the second film formation method. FIG. 3 is a diagram showing the gas composition and pressure during film formation of each sample synthesized in Example 1. FIG. 4 is a diagram showing the Raman scattering spectrum of each sample synthesized in Example 1. FIG. 5 is a diagram showing the gas composition and pressure during film formation of each sample synthesized in Example 2. FIG. 6 is a diagram showing the Raman scattering spectrum of each sample synthesized in Example 2. FIG. 7 is a diagram showing the composition range of the raw material gas that allows diamond to be synthesized by a conventional CVD method.

[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. Apparatus 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, metals such as iron, titanium, copper, and cemented carbide, other alloy materials such as tool steel, SiC, GaN, AlN, BN, and diamond.

[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 this. 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, it may be immersed in an acidic solution such as a nitric acid aqueous solution to remove Co from the substrate, or the surface of WC (tungsten carbide) particles may be treated with an alkaline solution such as diluted NaOH, and then the seeding treatment described above may be performed.

[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 a high-frequency wave to the antenna 3 to generate an inductively coupled plasma P within the vacuum vessel 2. In this film formation apparatus 100, when a high-frequency wave is applied 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] A gas G such as a source gas is introduced into the vacuum vessel 2 via, for example, a flow rate regulator (not shown) and a plurality of gas inlets 21 arranged in a direction along the antenna 3 .

[0027] A substrate holder 8 for holding a 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 for 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 thereto. 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 a 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 chamber 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 chamber 2. The gas supply mechanism 7 is configured to be able to supply a source gas containing at least C (carbon), H (hydrogen), and O (oxygen), and specifically, H ２ Gas, CH ４ Gas and CO ２ The gas supply mechanism 7 is configured to be able to supply a source gas containing C, H, and O into the vacuum chamber 2. ２ Gas, CH ４ Gas and CO ２ In addition to or instead of the gas, any other gas may be configured to be supplied as a source gas.

[0029] The gas supply mechanism 7 is ２ Gas, CH ４ Gas and CO ２ The gas supply mechanism 7 of this embodiment is configured to supply the gases at any desired flow rate. ２ Gas, CH ４ Gas and CO ２The source gas is configured to be supplied by adjusting 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 contained therein (O / (O+H)) 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 source gas. This catalyst gas functions as a catalyst during plasma generation and promotes decomposition of the source gas. Specifically, the gas supply mechanism 7 is configured to supply the catalyst gas so that its proportion of the total flow rate of all gases supplied into the vacuum chamber 2 (here, the total flow rate of the source 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 so as to follow the surface of the substrate W. In this embodiment, a plurality of linear antennas 3 are disposed in parallel so as to follow 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 (e.g., two, four, six, 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, in order 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 multiple 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 2 a, 2 b 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, packings 12. The antenna 3 is supported via the insulating members 11 in a state in which it is electrically insulated from the opposing side walls 2 a, 2 b of the vacuum vessel 2. The gap between each insulating member 11 and the vacuum vessel 2 is also vacuum-sealed by, for example, packings 13. The insulating members 11 are made of, for example, ceramics such as alumina, quartz, or engineering plastics such as polyphenylene sulfide (PPS) and polyether ether ketone (PEEK).

[0034] The antenna 3 is a so-called LC antenna having 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), tubular insulating elements 32 (hereinafter referred to as insulating pipes 32) that are provided between adjacent metal pipes 31 to insulate the metal pipes 31, and capacitors 33 that are capacitive elements that are provided between adjacent metal pipes 31 and electrically connected in series with the conductor elements 31 and capacitors 33. The conductor elements 31 function as the L portion, and the capacitors 33 function 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 is 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, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon, or the like.

[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 preventing the metal pipe 31 from being sputtered by charged particles (mainly ions), which would cause 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 side wall 2a or 2b serves as the grounded end 3b.

[0042] Here, a high frequency is applied to the power supply 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 Forming Method) First, the substrate W is placed on the substrate holder 8 in the vacuum chamber 2 of the film forming apparatus 100, and the vacuum chamber 2 is evacuated by the vacuum exhaust device 6. The substrate W is heated by 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 forming 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 having a grain size of 1000 nm or more, the temperature of the substrate W is preferably set to 700° C. or more and 1200° C. or less.

[0045] (Supply of Source Gas) Next, H as a source gas is supplied by the gas supply mechanism 7. ２ Gas, CH ４ Gas and CO ２ The gas is supplied at a predetermined flow rate into the vacuum chamber 2. In the film forming method of this embodiment, the atomic ratio of O atoms, C atoms, and H atoms in the source gas is adjusted to fall within the shaded range shown in the composition ternary diagram (C-H-O diagram) of FIG. ２Gas, CH ４ Gas and CO ２ The flow rate of each gas is adjusted. The atomic ratio of each atom is explained below.

[0046] (Ratio of Number of Oxygen and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained therein (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. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0047] (Ratio of Number of Oxygen and Carbon Atoms) In the raw material gas to be supplied, the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms contained therein (C / (O+C)) is preferably 30 at % or more and 45 at % or less, more preferably 35 at % or more and 45 at % or less. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0048] (Ratio of Number of Carbon and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms (H / (C+H)) is preferably 40 at % or more and 90 at % or less, more preferably 50 at % or more and 80 at % or less. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0049] (Supply of catalytic gas) Furthermore, a catalytic gas such as Ar gas is supplied into the vacuum chamber together with the raw material 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% or more and 90% or less, more preferably 75% or more and 90% or less. By setting the flow rate of the supplied catalytic gas in this range, it is possible to prevent the ionization of gases that are easily ionized, such as Ar, into CH during film formation. ４ C, which transfers energy to ２As a result, as shown in FIG. 3, in the emission spectrum of the inductively coupled plasma generated, the C ２ The ratio of the radical emission intensity can be set to 30% or more and 300% or less, more preferably 90% or more and 250% or less.

[0050] (Pressure in Vacuum Chamber) Then, while the raw material gas and catalyst gas are introduced by the gas supply mechanism 7, the pressure in 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] (Generation of plasma and formation of carbon-based thin film) 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, and forming 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 0.5 W / cm is preferable. ２ More preferably, 1 W / cm or more ２ More preferably, the power density is 1000 W / cm. ２ Preferably, 100 W / cm or less ２ More preferably, 50 W / cm or less ２ The following is even more preferred:

[0052] (Second Film Forming Method) Next, a second film forming method will be described, which differs from the first film forming method in the gas composition ratio of the supplied raw material gas. First, a substrate W is placed on a substrate holder 8 in the vacuum chamber 2 of the film forming apparatus 100, and the vacuum chamber 2 is evacuated using the vacuum exhaust device 6. The substrate W is heated using a 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 forming method, when synthesizing a carbon-based thin film containing diamonds with a particle size of 50 nm or less, it is preferable to supply a hydrogen-rich raw material gas and set the temperature of the substrate W 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, it is preferable to supply an oxygen-rich raw material gas and set the temperature of the substrate W to 800°C or lower.

[0053] (Supply of Source Gas) Next, H as a source gas is supplied by the gas supply mechanism 7. ２ Gas, CH ４ Gas and CO ２ The gas is supplied at a predetermined flow rate into the vacuum chamber 2. In the film forming method of this embodiment, the atomic ratio of O atoms, C atoms, and H atoms in the source gas is adjusted to fall within the shaded range shown in the composition ternary diagram (C-H-O diagram) of FIG. ２ Gas, CH ４ Gas and CO ２ The flow rate of each gas is adjusted. The atomic ratio of each atom is explained below.

[0054] (Ratio of Number of Oxygen and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained therein (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. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0055] (Ratio of Number of Oxygen and Carbon Atoms) In the raw material gas to be supplied, the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms contained therein (C / (O+C)) is preferably 45 at % or more and 70 at % or less. ２Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0056] (Ratio of Number of Carbon and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms contained therein (H / (C+H)) is preferably 60 at % or more and 95 at % or less, more preferably 90 at % or more and 95 at % or less. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0057] (Supply of catalytic gas) Furthermore, a catalytic gas such as Ar gas is supplied into the vacuum chamber together with the raw material 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% or more and 95% or less, more preferably 70% or more and 90% or less. By setting the flow rate of the supplied catalytic gas in this range, the ratio of the C relative to the emission intensity of Hα radicals in the emission spectrum of the generated inductively coupled plasma is ２ The ratio of the radical emission intensity can be set to 30% or more and 300% or less, more preferably 90% or more and 250% or less.

[0058] (Pressure in Vacuum Chamber) Then, while the raw material gas and catalyst gas are introduced by the gas supply mechanism 7, the pressure in 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] (Generation of plasma and formation of carbon-based thin film) 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, and forming 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 0.5 W / cm is preferable. ２More preferably, 1 W / cm or more ２ More preferably, the power density is 1000 W / cm. ２ Preferably, 100 W / cm or less ２ More preferably, 50 W / cm or less ２ The following is even more preferred:

[0060] 3. Effects of the Present Embodiment According to the film forming apparatus 100 and the film forming method of the present embodiment configured as described above, by using the inductively coupled plasma P generated by the high frequency induction electric field, CO ２ Decomposition of carbon atoms such as carbon dioxide and oxygen atoms is possible over a wide range, and the generation of oxygen-containing radicals can be promoted. Furthermore, since the inductively coupled plasma is generated by the antenna 3, activation can be continued 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 source gases with a wide composition range that could not be achieved using conventional CVD apparatuses, and also makes it possible to form carbon-based thin films with a larger area than conventional plasma CVD apparatuses. Furthermore, by introducing Ar gas as a catalyst gas, C ２ It can also promote the generation of radicals. ２ By forming a film on the substrate W using radicals or the like and removing non-diamond components using oxygen-containing radicals and hydrogen radicals, it becomes 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 of the diamond film.

[0062] The film formation apparatus 100 of the present invention is not limited to the above-described embodiment. For example, in the film formation apparatus 100 of the above-described embodiment, the antenna 3 for generating inductively coupled plasma is disposed inside the vacuum chamber 2, but this is not limiting. The film formation apparatus 100 of other embodiments 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] (Aspect 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 composition of the source gas supplied by the gas supply mechanism has a ratio of O atom concentration to the total concentration of O atoms and H atoms of 10 at % or more and 60 at % or less.

[0066] (Aspect 3) A film forming 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 emission spectrum of the inductively coupled plasma is C relative to the emission intensity of Hα radicals. ２ A film forming apparatus according to any one of aspects 1 to 4, wherein the ratio of the emission intensity of radicals is 30% or more and 300% or less.

[0069] (Aspect 6) The film forming 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 forming 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 forming 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 spectroscopy analysis at 325 nm excitation of 1333 cm －１ The diamond peak intensity around 1550 cm －１ A 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] (Aspect 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 Cr-Si ...

[0075] 4. Examples 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 plasma CVD using the above-described film deposition apparatus 100, with the source gas composition, vacuum chamber 2 pressure, and Ar gas flow rate ratio 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 section). The source gas flow rates, source gas compositions, Ar gas flow rate ratios, and pressure within 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: 13.56 MHz Power density of supplied high-frequency power: 1.4 W / cm ２ ・Substrate temperature: 500℃

[0077] 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. 6. As shown in FIG. 6, in samples No. 1 to No. 4 in which an LC antenna was used, the ratio of the concentration of O atoms 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 was 1333 cm －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 plasma CVD using the above-described film deposition apparatus 100, with the source gas composition, the pressure in the vacuum chamber 2, and the Ar gas flow rate ratio being varied. 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: 13.56 MHz Power density of supplied high-frequency power: 1.4 W / cm ２ ・Substrate temperature: 500℃

[0079] The crystallinity of each film-formed sample 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 , an LC antenna was used, and the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms in the source gas was 5 at% or more and 45 at% or less, the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms was 45 at% or more and 70 at% or less, the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms was 60 at% or more and 95 at% or less, the flow rate ratio of Ar gas to the total gas was 50% or more and 95% or less, and the pressure in the vacuum chamber 2 was 7 Pa or more and 100 Pa or less (specifically, 15 Pa). For samples No. 12 to No. 15, the crystallinity was 1333 cm －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.

[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.

[0081] 100: Plasma CVD device 2: Vacuum vessel 3: Antenna 7: Gas supply mechanism W: Substrate P: Plasma

Claims

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; a high-frequency power supply for supplying high-frequency current to the antenna; and a gas supply mechanism for supplying a source gas containing C, H, and O into the vacuum vessel, wherein the device 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.

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

3. A film forming apparatus as described in claim 1, wherein the gas supply mechanism supplies a catalyst gas into the vacuum vessel 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 vessel is 50% or more and 90% or less.

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 the C relative to the emission intensity of Hα radicals. 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. 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. The film forming apparatus according to claim 1, wherein said antenna is linear and has a length of 20 cm or more.

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

9. The diamond film exhibited a Raman spectroscopy peak at 1333 cm －１ The diamond peak intensity around 1550 cm －１ 2. The film forming apparatus according to claim 1, 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 film formation method in which 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 capacitance 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.

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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